Showing papers in "Journal of Clinical Investigation in 1975"

Wall stress and patterns of hypertrophy in the human left ventricle.

Abstract: It is generally recognized that chronic left ventricular (LV) pressure overload results primarily in wall thickening and concentric hypertrophy, while chronic LV volume overload is characterized by chamber enlargement and an eccentric pattern of hypertrophy. To assess the potential role of the hemodynamic factors which might account for these different patterns of hypertrophy, we measured LV wall stresses throughout the cardiac cycle in 30 patients studied at the time of cardiac catheterization. The study group consisted of 6 subjects with LV pressure overload, 18 with LV volume overload, and 6 with no evidence of heart disease (control). LV pressure, meridional wall stress (sigman), wall thickness (h), and radius (R) were measured in each patient throughout the cardiac cycle. For patients with pressure overload, LV peak systolic and end diastolic pressures were significantly increased (220 plus or minus 6/23 plus or minus 3 mm Hg) compared to control (117 plus or minus 7/10 plus or minus 1 mm Hg, P less than 0.01 for each). However, peak systolic and end diastolic (sigman) were normal (161 plus or minus 24/23 plus or minus 3 times 10-3 dyn/cm-2) compared to control (151 plus or minus 14/17 plus or minus 2 times 10-3 dyn/cm-2, NS), reflecting the fact that the pressure overload was exactly counterbalanced by increased wall thickness (1.5 plus or minus 0.1 cm for pressure overload vs. 0.8 plus or minus 0.1 cm for control, P less than 0.01). For patients with volume overload, peak systolic (sigman) was not significantly different from control, but end diastolic (sigmam) was consistently higher than normal (41 plus or minus 3 times 10-3 dyn/cm-2 for volume overload, 17 plus or minus 2 times 10-3 dyn/cm-2 for control, P less than 0.01). LV pressure overload was associated with concentric hypertrophy, and an increased value for the ratio of wall thickness to radius (h/R ratio). In contrast, LV volume overload was associated with eccentric hypertrophy, and a normal h/R ratio. These data suggest the hypothesis that hypertrophy develops to normalize systolic but not diastolic wall stress. We propose that increased systolic tension development by myocardial fibers results in fiber thickening just sufficient to return the systolic stress (force per unit cross-sectional area) to normal. In contrast, increased resting or diastolic tension appears to result in gradual fiber elongation or lengthening which improves efficiency of the ventricular chamber but cannot normalize the diastolic wall stress.

The effect of insulin on renal handling of sodium, potassium, calcium, and phosphate in man.

Abstract: The effects of insulin on the renal handling of sodium, potassium, calcium, and phosphate were studied in man while maintaining the blood glucose concentration at the fasting level by negative feedback servocontrol of a variable glucose infusion. In studies on six water-loaded normal subjects in a steady state of water diuresis, insulin was administered i.v. to raise the plasma insulin concentration to between 98 and 193 muU/ml and infused at a constant rate of 2 mU/kg body weight per min over a total period of 120 min. The blood glucose concentration was not significantly altered, and there was no change in the filtered load of glucose; glomerular filtration rate (CIN) and renal plasma flow (CPAH) were unchanged. Urinary sodium excretion (UNaV) decreased from 401 plus or minus 46 (SEM) to 213 plus or minus 18 mueq/min during insulin administration, the change becoming significant (P smaller than 0.02) within the 30-60 min collection period. Free water clearance (CH2O) increased from 10.6 plus or minus 0.6 to 13 plus or minus 0.5 ml/min (P smaller than 0.025); osmolar clearance decreased and urine flow was unchanged. There was no change in plasma aldosterone concentration, which was low throughout the studies, and a slight reduction was observed in plasma glucagon concentration. Urinary potassium (UKV) and phosphate (UPV) excretion were also both decreased during insulin administration; UKV decreased from 66 plus or minus 9 to 21 plus or minus 1 mueq/min (P smaller than 0.005), and tupv decreased from 504 plus or minus 93 to 230 plus or minus 43 mug/min (P smaller than 0.01). The change in UKV was associated with a significant reduction in plasma potassium concentration. There was also a statistically significant but small reduction in plasma phosphate concentration which was not considered sufficient alone to account for the large reduction in UPV. Urinary calcium excretion (UCaV) increased from 126 plus or minus 24 to 200 plus or minus 17 mug/min (P smaller than 0.01). These studies demonstrate a reduction in UNaV associated with insulin administration that occurs in the absence of changes in the filtered load of glucose, glomerular filtration rate, renal blood flow, and plasma aldosterone concentration. The effect of insulin on CH2O suggests that insulin's effect on sodium excretion is due to enhancement of sodium reabsorption in the diluting segment of the distal nephron.

Regional myocardial functional and electrophysiological alterations after brief coronary artery occlusion in conscious dogs.

Abstract: The time relationship for recovery of mechanical function, the intramyocardial electrogram and coronary flow after brief periods of regional myocardial ischemia, was studied in conscious dogs. Total left vemtricular (LV) function was assessed with measurements of LV systolic and diastolic pressures, rate of change of LV pressure (dP/dt), and dP/dt/P. Regional LV function was assessed with measurements of regional segment length and velocity of shortening. An implanted hydraulic occluder on either the left anterior descending or circumflex coronary artery was inflated for 5- and 15-min periods on separate days. A 5-min occlusion depressed overall LV function transiently, but just before release of occlusion overall function had nearly returned to control. At this time regional function in the ischemic zone was still depressed to the point of absent shorteining or paradoxical motion during systole and was associated with marked ST segment elevation (+ 10 +/- 2.2 mV) at the site where function was measured. With release of occlusion and reperfusion the intramyocardial electrogram returned to normal within 1 min, and reactive hyperemia subsided by 5-10 min. In contrast to the rapid return to preocclusion levels for coronary flow and the electrogram, regional mechanical function remained depressed for over 3 h. A 15-min coronary occlusion resulted in an even more prolonged (greater than 6 h) derangement of function in the ischemic zone. Thus, brief periods of coronary occlusion result in prolonged impairement of regional myocardial function which could not have been predicted from the rapid return of the electrogram and coronary flow. These observations indicate that brief interruptions of coronary flow result either in a prolonged period of local ischemia or that alterations of mechanical induced by ischemia far outlast the repayment of the oxygen debt.

The mechanism of the effect of aspirin on human platelets. I. Acetylation of a particulate fraction protein.

Abstract: Aspirin (acetylsalicylic acid) inhibits platelet prostaglandin synthesis and the ADP- and collagen-induced platelet release reaction. The mechanism of the inhibitory effect is unknown but may involve protein acetylation, since aspirin acetylates a variety of substrates, including platelet protein. We have examined the relationship between protein acetylation and aspirin's physiologic effect on platelets. Suspensions of washed human platelets were incubated at 37 degrees C with (3H)aspirin, and incorporation of radioactivity into protein was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Exposure to (acetyl-3H)aspirin but not (aromatic ring-3H)aspirin resulted in radioactive labeling of three platelet proteins, suggesting that the drug acetylates these three proteins. The acetylation of two of the proteins (located in the supernatant fraction) was not saturable, implying that these reactions may not be physiologically significant. Acetylation of the third protein, approximate mol wt 85,000 (located in the particulate fraction), saturated at an aspirin concentration of 30 muM and was complete within 20 min. Platelets prepared from aspirin-treated donors did not incorporate any (acetyl-3H)aspirin radioactivity into the particulate protein for 2 days after drug treatment and did not show full pretreatment uptake of radioactivity for 12 days thereafter. The course of increasing incorporation of (acetyl-3H)aspirin radioactivity parralleled that of platelet turnover. Therefore, in addition to its saturability, acetylation of the particulate fraction protein by aspirin was permanent. In two respects, the inhibition of platelet function by aspirin correlates well with the aspirin-mediated acetylation of the particulate fraction protein. Both persist for the life-span of the aspirin-treated platelet, and both occur at a similar saturating aspirin concentration. The evidence suggests that the physiologic effect of aspirin on human platelets is produced by acetylation of a single protein located in the particulate fraction. The acetylated protein may be related to cyclo-oxygenase, the prostaglandin G2 biosynthetic enzyme.

Leucine. A possible regulator of protein turnover in muscle.

Abstract: Incorporation of radiolabeled precursors into muscle proteins was studied in isolated rat hemidiaphragms. A mixture of three branched-chain amino acids (0.3 mM each) added to media containing glucose stimulated the incorporation of [14C]lysine into proteins. When tested separately, valine was ineffective, isoleucine was inhibitory, but 0.5 mM leucine increased the specific activity of muscle proteins during incubation with [14C]lysine or [14C]acetate in hemidiaphragms from fed or fasted rats incubated with or without insulin. Preincubation with 0.5 mM leucine increased the specific activity of muscle proteins during a subsequent 30- or 60-min incubation with [14C]lysine or [14C]pyruvate without leucine. Preincubation with other amino acids (glutamate, histidine, methionine, phenylalanine, or tryptophan) did not exert this effect. When hemidiaphragms were incubated with a mixture of amino acids at concentrations found in rat serum and a [14C]lysine tracer, the specific activity of muscle proteins increased when leucine in the medium was raised from 0.1 to 0.5 mM. Experiments with actinomycin D and cycloheximide suggested that neither RNA synthesis nor protein synthesis are required for the initiation of the leucine effect. Leucine was not effective when added after 1 h preincubation without leucine. The concentration of lysine in the tissue water of diaphragms decreased during incubation with 0.5 mM leucine in the presence or absence of cycloheximide, suggesting that leucine inhibited protein degradation. During incubation with [3h]tyrosine (0.35 mM) the addition of 0.5 mM leucine increased the specific activity of muscle proteins, while the specific activity of intracellular tyrosine remained constant and its concentration decreased, suggesting that leucine also promoted protein synthesis. The concentration of leucine in muscle cells or a compartment thereof may play a role in regulating the turnover of muscle proteins and influence the transition to negative nitrogen balance during fasting, uncontrolled diabetes, and the posttraumatic state. Leucine may play a pivotal role in the protein-sparing effect of amino aicds.

Complement and immunoglobulins stimulate superoxide production by human leukocytes independently of phagocytosis.

Abstract: Human peripheral blood polymorphonuclear leukocytes, when exposed to appropriate stimuli, generate significant amounts of superoxide anion (O-.2), a highly reactive molecule which is possibly involved in bacterial killing. Since the subcellular localization and mechanism of activation of O-.2 generating systems are unknown, we have investigated superoxide dismutase-inhibitable cytochrome c reduction (attributable to O-.2) by, and lysosomal enzyme release from, normal polymorphonuclear leukocytes and cells rendered incapable of ingesting particles by treatment with cytochalasin B. Neither phagocytosis nor lysosomal degranulation were prerequisites for enhanced O-.2 generation. Cytochalasin B-treated cells exposed to (a) serum-treated zymosan, a C3b receptor stimulus; (b) heat aggregated human IgG, an Fc receptor stimulus; and (c) the complement component, C5a, generated enhanced amounts of O-.2 in a time and concentration-dependent fashion. These cells also responded by releasing lysosomal enzymes, but there was no correlation between the ability of any immune reactant to provoke enzyme release and its ability to stimulate O-.2 generation. The three stimuli also enhanced O-.2 generation by normal (untreated) polymorphonuclear leukocytes, but only serum-treated zymosan and aggregated IgG were capable of provoking lysosomal enzyme release from normal cells. Untreated zymosan and native IgG neither stimulated O-.2 production nor provoked lysomal enzyme release. Since enhanced O-.2 production was stimulated by immune reactants in the absence of phagocytosis, the O-.2 generating system is very likely associated with the external plasma membrane of the polymorphonuclear leukocyte. Leukocyte membrane receptors for complement and immunoglobulins may therefore not only serve in particle recognition but also may initiate biochemical events which accompany phagocytosis and killing.

The role of superoxide anion generation in phagocytic bactericidal activity. Studies with normal and chronic granulomatous disease leukocytes.

Abstract: The capacity of human phagocytes to generate superoxide anion (O2-), a free radical of oxygen, and a possible role for this radical or its derivatives in the killing of phagocytized bacteria were explored using leukocytes from normal individuals and patients with chronic granulomatous disease (CGD). Superoxide dismutase, which removes O2-, consistently inhibited phagocytosis-associated nitroblue tetrazolium (NBT) reduction indicating the involvement of O2- in this process. Similarly, superoxide dismutase inhibited the luminescence that occurs with phagocytosis, implicating O2- in this phenomenon, perhaps through its spontaneous dismutation into singlet oxygen. Subcellular fractions from homogenates of both normal and CGD leukocytes generated O2- effectively in the presence of NADH as substrate. However, O2- generation by intact cells during phagocytosis was markedly diminished in nine patients with CGD. Leukocytes from mothers determined to be carriers of X-linked recessive CGD by intermediate phagocytic reduction of NBT elaborated O2- to an intermediate extent, further demonstrating the interrelationship between NBT reduction and O2- generation in phagocytizing cells. Activity of superoxide dismutase, the enzyme responsible for protecting the cell from the damaging effects of O2-, was approximately equal in homogenates of normal and CGD granulocytes. Polyacrylamide electrophoresis separated this activity into a minor band that appeared to be the manganese-containing superoxide dismutase associated with mitochondria and a more concentrated, cyanide-sensitive, cytosol form of the enzyme with electrophoretic mobility that corresponded to that of erythrocyte cuprozinc superoxide dismutase. Superoxide dismutase inhibited the phagocytic killing of Escherichia coli, Staphylococcus aureus, and Streptococcus viridans. A similar inhibitory effect was noted with catalase which removes hydrogen peroxide. Neither enzyme inhibited the ingestion of bacteria. Peroxide and O2- are believed to interact to generate the potent oxidant, hydroxyl radical (.OH). A requirement for .OH in the phagocytic bactericidal event might explain the apparent requirement for both O2- and H2O2 for such activity. In agreement with this possibility, benzoate and mannitol, scavengers of .OH, inhibited phagocytic bactericidal activity. Generation of singlet oxygen from O2- and .OH also might explain these findings. It would seem clear from these and other studies that the granulo cyte elaborates O2- as a concomitant of the respiratory burst that occurs with phagocytosis. To what extent the energy inherent in O2- is translated into microbialdeath through O2- itself, hydrogen peroxide, .OH, singlet oxygen, or some other agent remains to be clearly defined.

The effects of age and liver disease on the disposition and elimination of diazepam in adult man.

Abstract: This study investigates the separate effects of age and hepatocellular liver disease on the disposition and elimination of diazepam (Valium) in man. The drug was given either by rapid intravenous injection (0.1 mg/kg) or orally (10 mg) to 33 normal volunteers rnaging in age from 15 to 82 yr as well as to 9 individuals with alcoholic cirrhosis, 8 with acute viral hepatitis, and 4 with chronic active hepatitis. In the normal individuals, the terminal plasma half-life of diazepam, (t 1/2 (B)) exhibited a striking age-dependence; at 20 yr the t 1/2 (beta) was about 20 h, but it increased linearly with age to about 90 h at 80 yr. The plasma clearance of diazepam in the majority of the normal subjects was between 20 and 32 ml/min and showed no significant age-dependence. Cigarette smoking did not affect the half-life or the clearance. Additionally, neither the plasma binding (97.4 plus or minus 1.2%, mean plus or minus SD) nor the blood/plasma concentration ratio (0.58 plus or minus 0.16) of diazepam showed any age-related changes (P greater than 0.05). By contrast, analysis of the intravenous data according to a two-compartment open model indicated that both the initial distribution space (V1) and the volume of distribution at steady state [Vd(ss)] of diazepam increased linearly with age (P less than 0.005). The increase in Vd(ss) was secondary to the change in V1. It appears then that the prolongation of t 1/2 (beta) of diazepam with age is primarily dependent on an increase in the initial distribution volume of the drug. The plasma concentration/time course of the metabolite, desmethyldiazepam, was also affected by age. In older individuals, the initial presence and the peak values of desmethyldiazepam were observed later and the metabolite was present in lower concentrations. Despite the profound prolongation of t 1/2 (theta) with age, the constancy of diazepam clearance indicates that drug plasma concentrations will not accumulate any more in the old than the young, and chronic dosage more in the old than the young, and chronic dosage modifications based on pharmacokinetic considerations are unnecessary. Data obtained in patients with liver disease were compared with those found in age-matched control groups. Patients with cirrhosis showed a more than twofold prolongation in the half-life of diazepam (105.6 plus or minus 15.2 vs. 46.6 plus or minus 14.2 h, P less than 0.001).

H2O2 release from human granulocytes during phagocytosis. I. Documentation, quantitation, and some regulating factors.

Abstract: The extinction of fluorescence of scopoletin during its oxidation by horseradish peroxidase (HPO) provides a highly sensitive and specific assay for small quantities of peroxide in solution. With this assay, the release of free H2O2 into the extracellular medium by phagocytizing human granulocytes has been documented and quantitated, and some of the regulating factors have been determined. Under basal conditions granulocytes released less than 0.01 nmol/ml of H2O2 (2.5 X 10-6 polymorphonuclear leukocytes/ml). Upon the addition of phagocyte particles (latex, opsonized yeast, or staphylococci), an abrupt increase in extracellular peroxide concentration was observed (greater than 50-fold above basal levels) after latencies as short as 10 s. Release reflected increased intracellular H2O2 production during phagocytosis in that it paralleled the respiratory burst and was absent when phagocytosis was prevented or when cells from patients with chronic granulomatous disease were utilized. Evidence that scpoletin oxidation occurred predominantly in the extracellular medium was obtained by demonstrating a marked inhibition when HPO was omitted from the reaction mixture or when exogenous catalase was added. Similarly, it was found that exogenous serum also inhibited scopoletin oxidation, apparently because of the presence of competing hydrogen donors. H2O2 formation and release were observed at rates which closely paralleled those of phagocytosis. With O2 consumption as an approximate index of H2O2 formation, the fractions released during maximal rates of particle uptake were calculated as follows: for latex, 15.7%; for staphylococci, 10.3%; and for yeast, 4.9%. It is postulated that release is due to diffusion of free H2O2 from an expanded intracellular pool of this substance that develops during phagocytosis. This poos represents tha net of increased synthesis versus catabolism by various enxymatic pathways for H2O2 disposal within the cells. The close relationship between rates of H2O2 formation and rates of phagocytosis by human granulocytes suggests a role for specialized areas of the cell membrane, involved in particle ingestion, in the trigger mechanism for H2O2 synthesis. The consequences of H2O2 release to other cells or organisms in the immediate environment of phagocytizing granulocytes remain to be determined.

Hormonal characteristics of the human menstrual cycle throughout reproductive life.

Abstract: The changes in serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FHS), estradiol, and progesterone that occur both early and late in reproductive life were characterized and compared with findings in young, normal women and in patients with certain menstrual disorders. A total of 50 complete menstrual cycles in 37 were examined. Five distinct patterns of hormonal regulation were found, three of which are reported here: (a) A long follicular phase and delayed follicular maturation in young women with long, unpredictable intermenstrual intervals from menarche; (b) a short follicular phase with increasing age and in short cycles in perimenopausal women; and (c) true anovulatory vaginal bleeding in long cycles in perimenopausal women. The short cycles before and during the menopausal transition were found to have lower E2 levels and high FSH concentrations throughout, while LH remained in the normal range. During long cycles in perimenopausal women, concentrations of LH and FSH were in the menopausal range. However, follicular maturation was observed months after high levels of gonadotropins were attained. These studies permit the characterization of the menstrual history of the normal woman in terms of the hormonal changes that occur and provide a basis for the definition of several disorders of follicular maturation.

Proinsulin, insulin, and C-peptide concentrations in human portal and peripheral blood.

Abstract: Concentrations of insulin, proinsulin, and C-peptide were measured in portal and peripheral venous blood in six nondiabetic, nonobese subjects. Portal vein samples were obtained by umbilical vein catheterization. Three subjects were studied with intravenous infusion of 25 g glucose, and three with 30 g arginine. Insulin and proinsulin were determined in the insulin immunoassay after separation by gel filtration, and C-peptide was measured by direct immunoassay. With both glucose and arginine stimulation, portal vein levels of all three peptides peaked at 90-120 s after the onset of the stimulus. Relative increases in insulin concentration were greater than those of proinsulin or C-peptide. In peripheral venous blood, maximal levels of the three peptides were observed later (2-5 min), and the increase in insulin relative toproinsulin and C-peptide was not as great. At the time of peak secretion, portal vein insulin and C-peptide approached equimolar concentrations, and proinsulin, as measured against an insulin standard, comprised approximately 2.5% of the total immunoreactive insulin. After stimulation by glucose or arginine, portal insulin, proinsulin and C-peptide levels were not correlated with the concentrations measured in simultaneously drawn peripheral samples. At all sampling times, however, significant correlation was found between insulin and C-peptide in both peripheral and portal blood. The results indicate that under the conditions studied, insulin and C-peptide are secreted in equimolar concentrations in man, and that proinsulin is secreted in the same proportion to insulin as found in the pancreas. Consideration of the relative secretory and metabolic rates of the three beta cell peptides explains their peripheral concentrations. The data further support the use of plasma C-peptide as an indicator of beta cell secretory function.

Effects of insulin and dietary myoinositol on impaired peripheral motor nerve conduction velocity in acute streptozotocin diabetes.

Abstract: The factors influencing the development of impaired sciatic motor nerve conduction velocity (MNCV) in acute experimental diabetes were examined. Decreased MNCV developed by the 14th day after streptozotocin administration but only in rats which became hyperglycemic. Insulin treatment, begun on day 3, failed to prevent imparied MNCV in diabetic rats in which improved or normal weight gain and a decreased degree of hyperglycemia was induced. However, insulin treatment prevented the development of impaired MNCV in a group of diabetic rats in which the tail vein plasma glucose concentration was never found to exceed 160 mg/dl during days 6 through 14, andin which the mean plus or minus SEM of the average plasma glucose concentration for each animal during the same period was 75 plus or minus 18 mg/dl. In normal rats fed diets containing 0.011% or 0.069% free myoinositol (a presumably normal range), sciatic nerve free myoinositol concentrations were 90- and 60-fold higher than those in plasma. On these diets the development of impaired MNCV in the diabetics was associated with a decrease in nerve free myoinositol as compared with nerves from normals fed the same diet, despite similar plasma levels in the normals and diabetics. Plasma and nerve free myoinositol increased with increasing dietary myoinositol content in both normals and diabetics, and nerve myoinositol content could be acutely increased by an i.p. myoinositol load. By supplementing the diets with 1.0% myoinositol, the difference in nerve myoinositol in normal and diabetic rats on day 14 was abolished; on this diet the development of impaired MNCV in the diabetics was moderated or totally prevented, despite persistent hyperglycemia and elevated nerve sorbitol and fructose concentrations. Insulin treatment that prevented impaired MNCV prevented a decrease in nerve myoinositol in diabetics. These studies suggest that insulin deficiency, and possibly hyperglycemia, are primary factors in the development of imparied MNCV in acute experimental diabetes. However, the development of impaired MNCV appears to be related in some manner to a derangement in the regulation of nerve free myoinositol content, which appears to be subject to modification by increases in plasma myoinositol concentration over a critical range.

Urinary prostaglandins. Identification and origin.

Abstract: Human urine was analyzed by mass spectrometry for the presence of prostaglandins. Prostaglandin E2 and F2alpha were detected in urine from females by selected ion monitoring of the prostaglandin E2-methylester-methoxime bis-acetate and the prostaglandin F2alpha-methyl ester-Tris-trimethylsilylether derivative. Additional evidence for the presence of prostaglandin F2alpha was obtained by isolating from female urine an amount of this prostaglandin sufficient to yield a complete mass spectrum. The methods utilized permitted quantitative analysis. The origin of urinary prostaglandin was determined by stimulating renal prostaglandin synthesis by arachidonic acid or angiotensin infusion. Arachidonic acid, the precursor of prostaglandin E2, when infused into one renal artery of a dog led to a significant increase in the excretion rate of this prostaglandin. Similarly, infusion of angiotensin II amide led to a significantly increased ipsilateral excretion rate of prostaglandin E2 and F2a in spite of a simultaneous decrease in the creatinine clearance. In man, i.v. infusion of angiotensin also led to an increased urinary eliminiation of prostaglandin E. These results show that urinary prostaglandins may originate from the kidney, indicating that renally synthesized prostaglandins diffuse or are excreted into the tubule. Thus, urinary prostaglandins are a reflection of renal prostaglandin synthesis and have potential as a tool to delineate renal prostaglandin physiology and pathology.

Platelet hypersensitivity induced by cholesterol incorporation.

Abstract: Platelets from individuals with familial hypercholesterolemia show increased sensitivity to the aggregating atents, epinephrine and ADP. Since the mechanism of this abnormal sensitivity is unknown, we examined, in vitro, the influence of the plasma lipid environment on the function of platelets. The composition of plasma lipids was altered by the addition of sonicated cholesterol-dipalmitoyl lecithin liposomes which were "cholesterol normal" (cholesterol-phospholipid mole ratio [C/P] equals 1.0, "cholesterol rich" (C/P eauals 2.2), or "cholesterol poor" (C/P equals 0). Cholesterol-normal liposomes had no influence on platelet lipids or platelet function. In contrast, after incubation for 5 h at 37 degrees C with cholesterol-rich liposomes, normal platelets acquired 39.2% excess cholesterol with no change in phospholipids or protein. The percent increase in platelet membrane cholesterol was three-fold that of the granule fraction. The acquisition of cholesterol by platelets was associated with a 35-fold increase in sensitivity to epinephrine-induced aggregation (P less than 0.001) and 15-fold increase to ADP aggregation (P less than 0.001), as determined both by aggregometry and by [13C]serotonin release. Response to thrombin or collagen was unchanged. Platelets incubated with cholesterol-poor liposomes underwent a selective loss of 21.4% cholesterol and this was associated with an 18-fold reduction in their sensitivity to epinephrine. These studies demonstrate that the cholesterol content of platelets is dependent on the lipid composition of the milier. Cholesterol acquired by platelets may exert its effect on platelet function by a modification of the platelet membrane.

Antibodies to cellular antigens in Sjögren's syndrome.

Abstract: An extract of human lymphocytes from continous cell culture was used as the antigen source to detect antibodies in sera of patients with Sjogren's syndrome (SS). Using double diffusion in agarose, 85 per cent of a selected group of patients had precepating antibodies. Three precipitating antigen-antibody systems were detected and were shown to be different from those described previously in othe systemic rheumatic diseases. The SS precipitating antibodies were temporarily classified as precipitins, A, B, and C. SS patinets with sicca syndrome but without clinical rheumatoid arthritis had precipitin systems A and/or B, and SS patients with associated rheumatoid arthritis had precipitin system C. Serum reactants were demonstrated by immuno-electrophoresis to migrate in the gamma globulin region. The precipitating activity of the serum factors was not destroyed by treatment with 2-mercaptoethanol and was not removed by absorption of rheumatoid factor from the sera. The reactivity of the lympuocyte antigens was destroyed by treatment with trypsin but not by deoxyribonuclease or ribonuclease.

Pulmonary mechanics by spectral analysis of forced random noise.

Abstract: The magnitude (Zrs) and phase angle (thetars) of the total respiratory impedance (Zrs), from 3 to 45 Hz, were rapidly obtained by a modification of the forced oscillation method, in which a random noise pressure wave is imposed on the respiratory system at the mouth and compared to the induced random flow using Fourier and spectral analysis. No significant amplitude or phase errors were introduced by the instrumentation. 10 normals, 5 smokers, and 5 patients with chronic obstructive lung disease (COPD) were studied. Measurements of Zrs were corrected for the parallel shunt impedance of the mouth, which was independently measured during a Valsalva maneuver, and from which the mechanical properties of the mouth were derived. There were small differences in Zrs between normals and smokers but both behaved approximately like a second-order system with thetars = 0 degree in the range of 5--9 Hz, and thetars in the range of +40 degrees at 20 Hz and +60 degrees at 40 Hz. In COPD, thetars remained more negative (compared to normals and smokers) at all frequencies and crossed 0 between 15 and 29 Hz. Changes in Zrs, similar in those in COPD, were also observed at low lung volumes in normals. These changes, the effects of a bronchodilator in COPD, and deviations of Zrs from second-order behavior in normals, can best be explained by a two-compartment parallel model, in which time-constant discrepancies between the lung parenchyma and compliant airway keep compliant greater than inertial reactance, resulting in a more negative phase angle as frequency is increased.

Effects of acute unilateral renal denervation in the rat.

Abstract: Studies were undertaken to characterize the renal responses to acute unilateral renal denervation and the mechanisms involved in these responses. Denervation was produced in anesthetized nondiuretic rats by application of phenol to the left renal artery. Studies were also performed in sham-denervated nondiuretic rats. Whole kidney and individual nephron studies were performed before and after denervation or sham denervation. Denervation increased urine volume from the left kidney to about twice its control value (P less than 0.001) and increased urinary sodium excretion from 332 neq min minus -1 to 1,887 neq min minus -1 (P less than 0.001). Glomerular filtration rate (GFR) and renal plasma flow (RPF) remained unchanged in both kidneys after the procedure. The innervated right kidney showed no changes in urine volume or in sodium excretion. After denervation, late proximal ratio of tubular fluid inulin concentration to that of plasma [(F/P)In] decreased from 2.23 to 1.50 (P less than 0.001) while single nephron GFR remained unchanged. Absolute reabsorption decreased from 16.5 to 9.9 n. min minus -1 (P less than 0.001). (F/P)In ratios were also decreased in early distal (from 6.21 to 3.18, P less 0.001) and late distal convolutions (from 16.41 to 8.33, P less than 0.001) during the experimental period. (F/P)Na ratios remained unchanged in the early distal convolutions, but increased from 0.18 to 0.38 (P less than 0.01) in late distal convolutions after denervation. Absolute Na reabsorption after denervation increased in the loop of Henle, distal convolution, and collecting ducts. Any changes in intrarenal hydrostatic pressures after denervation were always small. There were no changes in GFR, RPF, urine volume, urinary sodium excretion, or late proximal (F/P)In after sham denervation. We conclude that the diuresis and natriuresis seen after acute renal denervation were caused by a marked depression of sodium and water reabsorption in the proximal tubule with partial compensation in more distal nephron segments. These responses appeared to be unrelated to systemic or intrarenal hemodynamic changes. The results demonstrate an effect of the renal nerves on proximal tubular function.

Prostaglandin-stimulated bone resorption by rheumatoid synovia. A possible mechanism for bone destruction in rheumatoid arthritis.

Abstract: Synovial tissue from patients with rheumatoid arthritis was maintained in organ culture for 3-14 days. Conditioned media from these synovial cultures contained bone resorption-stimulating activity, measured in vitro by using calcium release from mouse calvaria as the assay system. The synovial cultures also produce prostaglandin E2 (PGE2) as measured by serologic methods. The production of both the bone resorption-stimulating activity and PGE2 was inhibited by more than 90% by treatment of the synovial cultures with indomethacin (5 mug/ml). In contrast, treatment of the synovial cultures with colchicine (0.1 mug/ml) caused a marked and parallel increase in the concentration of both bone resorption-stimulating activity and PGE2 in the conditioned media. The bone resorption-stimulating activity was quantitatively extracted into diethyl ether. Within the limits of experimental error, all of the bone resorption-stimulating activity in medium was accounted for by its content of PGE2, itself a potent osteolytic factor. We conclude that the bone resorption-stimulating activity produced by rheumatoid synovia in culture is PGE2.

Apoprotein composition of very low density lipoproteins of human serum.

Abstract: Methods for quantitation of the major apoproteins of human serum very low density lipoprotein have been developed employing tetramethylurea, which delipidates the lipoprotein and selectively precipitates apolipoprotein B. Six soluble apoproteins are separated by electrophoresis in polyacrylamide gel. One of these is a previously unrecognized species of R-alanine (R4-alanine), more anionic than the R3-alanine polypeptide. Conditions of staining have been found which yield reproducibly linear chromogenic response with native lipoprotein and with each purified apoprotein. Recovery of protein in the seven species measured accounts for over 97% of the total in the very low density lipoprotein of normolipidemic individuals and in most samples from individuals with endogenous hyperlipemia. The mean content of apolipoprotein B in 43 samples from normolipidemic subjects was 36.9(+/-1.2 SEM)% of total protein, The distribution of the major soluble apoproteins as mean (+/-SEM) percentage of the soluble fraction was : R-serine, 5.3+/-o.5; arginine-rich, 20.6+/-1.0; R-glutamic, 10.6+/-0.4; R2-alanine, 28.3+/-0.7; R3-alanine, 26.9+/-0.5; and R4-alanine, 8.0+/-0.5. Distribution of the apoproteins was a function of particle diameter of very low density lipoprotein in fractions separated by gel permeation chromatography and by density gradient ultracentrifugation. In fractions below 700-800 A, apolipoprotein B comprised an increasing percentage of the total protein with decreasing particle diameter. Among the soluble proteins the percentage of the arginine-rich and R-serine polypeptides increased and that of the R-glutamic polypeptide declined progressively with decreasing particle size. Apoprotein distribution was similar in fractions of similar particle size from normolipidemic and hyperlipemic subjects with the exception that all fractions from the hyperlipemic subjects contained more R-serine and some, more arginine rich polypeptide. Even in the absence of chylomicrons, the distribution of soluble apoproteins in particles of diameters greater than 700-800 A was usually similar to that of the smallest particles. This suggests that the largest particles may include products of the partial catabolism of chylomicrons.

Effects of obesity and caloric intake on biliary lipid metabolism in man

Abstract: The effects of obesity and caloric intake on biliary lipid metabolism were investigated in a series of related studies. The degree of saturation of gallbladder bile with cholesterol was found to be significantly higher in a group of 23 obese healthy subjects than in a group of 23 nonobese controls matched for age, sex, and race. Bile was also significantly more saturated in 11 obese subjects before than after weight reduction. To determine whether supersaturated bile in obesity is due to excessive secretion of cholesterol or to deficient secretion of bile acids and phospholipids, the hepatic outputs of these three lipids were measured during constant duodenal infusion of formula in the same 11 subjects before and after weight reduction. Weight reduction resulted in significant reduction of cholesterol output but not of bile acid or phospholipid output. Moreover, very obese subjects were found to have cholesterol secretion rates markedly higher than less obese subjects previously studied by the same method. In obese subjects, bile was supersaturated with cholesterol despite increased bile acid pool sizes and increased secretion rates of bile acids and phospholipids. Supersaturated bile in the obese could therefore be attributed to a single defect in lipid secretion, namely, an excessive output of cholesterol. To determine whether the rate of caloric intake can account for the effects of obesity on biliary lipid composition and secretion, nine obese white men were studied on a weight maintenance diet and then during weight reduction on a 1,000 cal diet. As compared to weight maintenance, chronic caloric restriction resulted in reduced outputs of cholesterol, bile acids, and phospholipids, reduced bile acid pool size, and reduced synthesis and fecal excretion of cholesterol. Saturation of bile with cholesterol did not decrease during weight reduction, evidently because of the mobilization of cholesterol from adipose stores and the marked reduction in bile acid and phospholipid output observed during chronic caloric restriction. Acute alterations in caloric infusion rates did not fully reproduce the effects of chronic administration of high and low calorie diets. Likewise, chronic intake of hypercaloric diets by nonobese subjects did not reproduce the cholesterol hypersecretion characteristic of the obese. Thus, increased cholesterol secretion in obese subjects could not be fully explained by the amount of calories they ingested to maintain stable weight. It is concluded that obesity is characterized by excessive hepatic secretion of cholesterol which results in supersaturated bile.

Modification of red cell membrane structure by cholesterol-rich lipid dispersions. A model for the primary spur cell defect.

Abstract: Cholesterol-rich membranes are the hallmark of "spur" red cells. Spur cells accumulate cholesterol from cholesterol-rich serum lipoproteins. Previous studies suggested that this added cholesterol is responsible for both the altered morphology and the destruction of spur cells. To examine this process in the absence of other serum factors, cholesterol-lecithin dispersions with varying amounts of unesterified cholesterol (C) relative to phospholipid (P) were prepared, and their influence on normal human red cells was studied. Cholesterol-rich lipid dispersions (C/P mole ration greater 1.0) transferred cholesterol to both red cell membranes and serum lipoproteins, and cholesterol-poor dispersions (C/P mole ration less 1.0) depleted red cells of cholesterol. Changes in membrane cholesterol paralleled changes in membrane surface area, as calculated from osmotic fragility, with a 0.22 percent variation in surface area per 1.0 percent variation in cholesterol content. Cold-induced compression of membrane surface area was increased in cholesterol-poor red cells (C/P equals 0.4), whereas the surface area of cholesterol-rich membranes (C/P equals 1.80) underwent no compression. Although the Na and K permeability of red cells severely depleted of cholesterol was increased, lesser degrees of depletion had no effect, and the permeability of cholesterol-rich cells was normal. However, increasing membrane cholesterol caused a progressive decrease in red cell deformability, as measured by filtration. Cholesterol-poor red cells were spherocytic in appearance and cholesterol-rich cells were broad and flat, indicative of their surface areas. In addition, cholesterol-rich cells had an irregular contour due to folding of the periphery of the cell. This shape abnormality was identical to that of both spur cells after splenectomy and normal red cells incubated in spur serum. Normalization of the C/P of spur serum by added phospholipid prevented the increase in membrane cholesterol and surface area and the transformation of cell shape. These studies establish that the cholesterol content of red cells is dependent on the C/P of their milieu, either lipoproteins or cholesterol-lecithin dispersions. Moreover, the surface area, deformability, and contour of cholesterol-rich red cells are a direct function of their increased membrane C/P. Although cholesterol-rich spur cells are further modified in the circulation of patients with spleens, this abnormality of the membrane lipid bilayer, induced by cholesterol-rich cholesterol-lecithin dispersions, represents the primary spur cell defect.

Effect of ketone infusions on amino acid and nitrogen metabolism in man.

Abstract: To evaluate the role of hyperketonemia in the hypoalaninemia and decreased protein catabolism of prolonged starvation, Na dl-beta-hydroxybutyrate was administered as a primed continuous 3-6-h infusion in nonobese subjects and in obese subjects in the postabsorptive state and after 3 days and 3-5 1/2 wk of starvation. An additional obese group received 12-h ketone infusions on 2 consecutive days after 5-10 wk of fasting. The ketone infusion in nonobese and obese subjects studied in the postabsorptive state resulted in total blood ketone acid levels of 1.1-1.2 mM, a 5-15 mg/100 ml decrease in plasma glucose, and unchanged levels of insulin, glucagon, lactate, and pyruvate. Plasma alanine fell by 21% (P smaller than 0.001) in 3 h. In contrast, other amino acids were stable or varied by less than 10%. Infusions lasting 6 h reduced plasma alanine by 37%, reaching levels comparable to those observed in prolonged starvation. Equimolar infusions of NaC1 and/or administration of NaHCO3 failed to alter plasma alanine levels. During prolonged fasting, plasma alanine, which had fallen by 40% below prefast levels, fell an additional 30% in response to the ketone infusion. In association with repeated prolonged (12 h) infusions in subjects fasted 5-10 wk, urinary nitrogen excretion fell by 30%, returning to base line after cessation of theinfusions and paralleling the changes in plasma alanine. Ketone infusins resulted in two- to fourfold greater increments in blood ketone acids in fasted as compared to postabsorptive subjects. It is concluded that increased blood ketone acid levels induced by infusions of Na DL-beta-hydroxybutyrate result in hypoalaninemia and in nitrogen conservation in starvation. These data suggest that hyperketonemia may be a contributory factor in the decreased availability or circulating alanine and reduction in protein catabolism characteristic of prolonged fastings9

Catalase, superoxide dismutase, and virulence of Staphylococcus aureus. In vitro and in vivo studies with emphasis on staphylococcal--leukocyte interaction.

Abstract: Since oxygen-free polymorphonuclear neutrophils (PMN) cannot kill Staphylococcus aureus normally, the usual mechanisms for PMN bactericidal activity probably involve hydrogen peroxide or superoxide. Catalase can destroy hydrogen peroxide, and superoxide dismutase breaks down superoxide. Experiments were performed to study the influence of these enzymes (which are found in staphylococci) on virulence for mice or on leukocyte-bacterial interaction. 15 staphylococcal strains were injected i.p. into mice to quantitate virulence. There was good correlation between staphylococcal catalase activity and mouse lethality (r equals 0.88) but no correlation between staphylococcal superoxide dismutase activity and mouse lethality (r equals 0.14). Exogenous catalase (10,000 U/ml) increased the virulence of low-catalase staphylococci, but exogenous superoxide dismutase (200 mug/ml) did not alter the virulence of staphyloccal strains. C14=labeled high-catalase or low-catalase staphylococci were ingested equally well by PMN, with or without the addition of exogenous catalase. A high-catalase staphylococcal strain was killed relatively poorly by PMN, and addition of exogenous catalase (but not superoxide dismutase) decreased the ability of PMN to kill a low-catalase strain. Iodination of bacterial proteins by PMN is related to hydrogen peroxide, and a high-catalase staphylococcal strain was iodinated only 63% as much as a low-catalase strain. Addition of exogenous catalase decreased iodination of the low-catalase strain by 23%. These findings suggest that staphylococcal catalase protects intraphagocytic microbes by destroying hydrogen peroxide produced by the phagocyte. Thus, catalase may be a significant staphylococcal virulence factor.

pH dependence of acid secretion and gastrin release in normal and ulcer subjects.

Abstract: By use of a recently described method, which estimates the rate of gastric acid secretion by measuring the rate of sodium bicarbonate infusion needed to keep intragastric pH constant, gastric acid secretion rates and changes in serum gastrin were measured in five normal subjects while gastric pH was kept at 5.5, 4.0, 3.0, or 2.5. Preliminary experiments revealed that the method did not accurately measure acid secretion at a pH lower than 2.5. Stimulation of acid secretion was produced by gastric instillation of a solution of amino acids and cornstarch. The secretion rate with the amino acid meal was highest at pH 5.5 and was 60% of that produced by a steak meal at the same pH. As the pH of the amino acid meal was decreased, there was a stepwise reduction in acid secretion so that at pH 2.5 the rate was only half as great as at pH 5.5. The amino acid meal produced increases in serum gastrin that were also less marked than those produced by a steak meal. With amino acid stimulation, serum gastrin responses were similar at pH 5.5, 4.0, and 3.0, but no increase in gastrin could be measured when the meal was maintained at pH 2.5. A group of six patients with duodenal ulcers was compared with seven normal subjects at pH 5.5 and 2.5. Ulcer patients released more gastrin and secreted more acid at each time period at both pH values. More important, the degree of inhibition at pH 2.5 was significantly less in ulcer patients. For example, during the 2nd h after stimulation acid secretion was inhibited by only 30% in ulcer patients compared with 70% in normal subjects. These findings suggest a defect in autoregulation of gastrin release and gastric acid secretion at low pH in ulcer patients which may play a role in pathogenesis of this disease.

Determinants of human adipose tissue lipoprotein lipase. Effect of diabetes and obesity on basal- and diet-induced activity.

Abstract: The role of insulin in the regulation of human adipose tissue lipoprotein lipase was evaluated. Adipose tissue heparin-releasable lipoprotein lipase (thought to be related to peripheral clearance of plasma triglycerides) was low in insulin-deficient, untreated hyperglycemic diabetic subjects (P less than 0.001) and treatment of hyperglycemia returned the activity to normal. In chronic hyperinsulinism, represented by obesity, heparin-releasable activity among control subjects was correlated to percent of ideal body weight (r=0.53, P less than 0.05) and to fat cell size (r=0.61, P less than 0.02). Acetone-ether powder lipoprotein lipase activity (presumed to reflect total tissue enzyme) was also related to percent of ideal body weight (r=0.76, P less than 0.001 for controls; r=0.67, P less than 0.05 for diabetics) and to fat cell size (r=0.71, P less than 0.01 for controls; r=0.85, P less than 0.01 for diabetics. Postprandial-stimulated insulin secretion was related to diet-induced changes in lipoprotein lipase in control subjects; both were dependent upon the amount of dietary carbohydrate. In contrast, the diabetic patients with low insulin responses, failed to increase lipoprotein lipase activity with feeding. The changes in heparin-releasable (r=0.66, P less than 0.01) and acetone-ether powder (r=0.69, P less than 0.01) activity during feeding were related to the percent increase in plasma insulin. Thus, insulin appears to be important in the regulation of human adipose tissue lipoprotein lipase activity. Elevated insulin levels in obesity and increased insulin secretion after eating were associated with increased lipoprotein lipase activity. Defects in insulin secretion, both in postabsorptive and postprandial states, are associated with low adipose tissue lipoprotein lipase and may lead to hypertriglyceridemia in diabetic man.

Williams trait. Human kininogen deficiency with diminished levels of plasminogen proactivator and prekallikrein associated with abnormalities of the Hageman factor-dependent pathways.

Abstract: An asymptomatic woman (Ms. Williams) was found to have a severe abnormality in the surface-activated intrinsic coagulation, fibrinolytic, and kinin-generating pathways. Assays for known coagulation factors were nromal while Fletcher factor (pre-kallikrein) was 45%, insufficient to account for the observed markedly prolonged partial thromboplastin time. Plasminogen proactivator was present at 20% of normal levels and addition of highly purified plasminogen proactivator containing 10% plasminogen activator partially corrected the coagulation and fibrinolytic abnormalities but not the kinin-generating defect. This effect was due to its plasminogen activator content. In addition, Williams trait plasma failed to convert prekallilrein to lakkilrein or release kinin upon incubation with kaolin. Kininogen antigen was undetectable. When normal plasma was fractionated to identify the factor that corrects all the abnormalities in Williams trait plasma, the Williams factor was identified as a form of kininogen by its behavior on ion exchange chromatography, gel filtration, disc gel electrophoresis, and elution from an anti-low molecular weight kininogen immunoadsorbent. High molecular weight kininogen as well as a subfraction of low molecular weight kininogen, possessed this corrective activity while the bulk of low molecular weight kininogen functioned only as a kallikrein substrate. Kininogen therefore is a critical factor required for the functioning of Hageman factor-dependent coagulation and fibrinolysis and for the activation of prekallikrein.

Role of the low density lipoprotein receptor in regulating the content of free and esterified cholesterol in human fibroblasts.

Abstract: The transfer of normal human fibroblasts from medium containing whole serum to medium devoid of lipoproteins produced a 90 percent decrease in the cellular content of cholesteryl esters and a 30 percent decrease in the free cholesterol content. When these lipoprotein-deprived cells were subsequently incubated with human low density lipoprotein (LDL), there was a 7-fold increase in the cellular content of esterified cholesterol and a 1.6-fold increase in the cellular content of free cholesterol. The concentration at which LDL produced its half-maximal effect in elevating cellular sterol content (30 mug/ml of LDL-cholesterol) was similar to the half-maximal concentration previously reported for high affinity binding of LDL to its cell surface receptor. High density lipoprotein (HDL) and whole serum from a patient with abetalipoproteinemia (neither of which contains a component that binds to the LDL receptor) did not produce a significant increase in the content of either cholesterol or cholesteryl esters in normal cells. Furthermore, in fibroblasts from patients with the homozygous form of familial hypercholesterolemia, which lack functional LDL receptors, LDL had no effect in raising the cellular content of either free or esterified cholesterol even when present in the medium at concentrations as high as 450 mug sterol/ml. It is concluded that LDL-receptor interactions constitute an important biochemical mechanism for the regulation of the cholesterol content of normal human fibroblasts. Moreover, when considered in light of current concepts of LDL metabolism in intact mammals, the present data suggest that a major function of plasma LDL may be to transport cholesterol from its site of synthesis in liver and intestine to its site of uptake in peripheral tissues.

Characterization of remnants produced during the metabolism of triglyceride-rich lipoproteins of blood plasma and intestinal lymph in the rat.

Abstract: The metabolism of intravenously injected large and small chylomicrons from intestinal lymph and of very low density lipoproteins from blood plasma was studied in functionally eviscerated "supradiaphragmetic" rats. For studies with lymph lipoproteins, recipient animals were injected with 4-amino-pyrazolopyrimidine 18 h before injection of lipoprotein to prevent secretion of very low density lipoproteins into their blood plasma. In all cases, most of the triglycerides (labeled with 14C) were rapidly metabolized, whereas cholesteryl esters (labeled with 3H) persisted in the blood. Most of the cholesteryl esters remained in smaller "remnant" lipoproteins, less dense that 1.006, which retained an apparently spherical shape, as determined by electron microscopy of negatively stained preparations. Whereas the diameters and chemical compositions of large chylomicrons were substantially different from those of small chylomicrons and very low density lipoproteins, all remnants were similar in these respects. Average remnant diameters were 400-600 A and remnants were enriched in cholesteryl esters and in protein insoluble in tetramethylurea. In addition to triglycerides, remnants were depleted of phospholiarticle size, the composition of remnants, like that of their precursors, was consistent with the "pseudomicellar" model of lipoproteins, in which a core of nonpolar lipids is covered by a monolayer of polar lipids and protein. These results domonstrate the fundamental similarity of the initial step in the metabolism of triglyceride-rich lipoproteins from intestinal mucosa and liver and show that loss of triglycerides from the core of the particles is accompanied by removal of polar components from the surface.

Conversion of very low density lipoprotein to low density lipoprotein. A metabolic study of apolipoprotein B kinetics in human subjects.

Abstract: The interrelationship between apolipoprotein B in very low density lipoprotein (VLDL-B) and in low density lipoprotein (LDL-B) was studied in seven normal and hyperlipidemic men and women, with purified radioiodinated VLDL. The time-course of the appearance of radioactivity in LDL was followed. As the specific activity curves intersected at the masimal height of the LDL-B curve, it was inferred that all or most LDL-B peptide is derived from VLDL-B peptide. This transfer was further quantitated in seven normotriglyceridemic subjects by simultaneous i.v. injection of purified 131I-VLDL and 125I-LDL. By a deconvolution method, a quantitative description of the rate of entry of 131Ivldl-b into 131I-LDL-B was derived by analysis of 131I-LDL-B and 125I-ldl-b radioactivity in plasma. The results indicate that approximately 90% of VLDL-B mass is converted into LDL-B in subjects with normal serum triglyceride concentrations. The synthetic rates of VLDL-B and LDL-B peptide were simultaneously measured in six normal subjects, and two patients with heterozygous familial hypercholesterolemia (type IIa). The turnover rates for VLDL-B and LDL-B peptide were similar in these subjects. The findings in the three parts of this study were consistent with the view that most if not all VLDL-B is converted into LDL-B peptide, and most if not all LDL-B is derived from VLDL-B peptide in normotriglyceridemic subjects.

Comparison of agents producing a neutrophilic leukocytosis in man. Hydrocortisone, prednisone, endotoxin, and etiocholanolone.

Abstract: To study the potential application of glucocorticosteroid administration for the measurement of the bone marrow neutrophil reserve response, blood neutrophil count changes were measured in normal subjects after the administration of intravenous hydrocortisone (25, 50, 100, 200, and 400 mg) and oral prednisone (5, 10, 20, 40, and 80 mg). The upper three doses of both steroids increased the blood neutrophil count by approximately 4,000 cells/mm3. The neutrophilia occurring after hydrocortisone (200 mg) and/or prednisone (40 mg) was compared with that observed after endotoxin (0.8 ng/kg) and etiocholanolone (0.1 mg/kg) in 14 normal subjects, 7 patients with Wegener's granulomatosis on cyclophosphamide therapy and 10 patients with chronic idiopathic neutropenia. The normal responses (mean increase of blood neutrophils/mm3 above base line +/- 1 SEM) were: hydrocortisone 4,220 +/- 320, prednisone 4,610 +/- 360, endotoxin 6,060 +/- 880, and etiocholanolone 3,780 +/- 440. In the patient studies, etiocholanolone gave the smallest mean responses, but, in general, the results were similar for all agents. These data indicate that these glucocorticosteroids can be used as equivalent agents to endotoxin and etiocholanolone for measuring the neutrophil reserve response.