Showing papers by "Baylor College of Medicine published in 1975"

Regional cerebral blood flow estimated by 133-xenon inhalation.

Abstract: A method is described for estimating the clearance rate and fractional blood flow of the fast (gray matter) compartment of the brain from the first ten minutes of 133Xe clearance curves, following a one-minute inhalation. Computer-simulated data were used to test the adequacy of the two-compartmental model employed, and to evaluate the stability of the parameters in the presence of random noise. A comparison was made between this approach and the previously reported three-compartmental analysis. Regional cerebral blood flow data were obtained on 48 young control subjects and 20 elderly demented patients. Hemispheral regional, and test-retest variations were determined, as well as differences between the groups.

Effect of the human plasma apolipoproteins and phosphatidylcholine acyl donor on the activity of lecithin: cholesterol acyltransferase.

Abstract: The human plasma apoproteins apoA-I and apoC-I enhanced the activity of partially purified lecithin: cholesterol acyltransferase five to tenfold with chemically defined phosphatidylcholine:cholesterol single bilayer vesicles as substrates. By contrast, apoproteins apoA-II, apoC-II, and apoC-III did not give any enhancement of enzyme activity. The activation by apoA-I and apoC-I differed, depending upon the nature of the hydrocarbon chains of phosphatidylcholine acyl donor. ApoA-I was most effective with a phosphatidylcholine containing an unsaturated fatty acyl chain. ApoC-I activated LCAT to the same extent with both saturated and unsaturated phosphatidylcholine substrates. Two of the four peptides obtained by cyanogen bromide cleavage of apoA-I retained some ability to activate LCAT. The efficacy of each of these peptides was approximately 25% that of the whole protein. Cyanogen bromide fragments of apoC-I were inactive. The apoproteins from HDL, HDL2, and HDL3, at low protein concentrations, were equally effective as activators of LCATand less effective than apoA-I. Higher concentrations of apoHDL, apoHDL2, and apoHDL3 inhibited LCAT activity. ApoC and apoA-II were both found to inhibit the activation of LCAT by apoA-I. The inhibition of LCAT by higher concentrations of apoHDL was not correlated with the aopA-II and apoC content.

Visual membranes: specificity of fatty acid precursors for the electrical response to illumination

Abstract: Rat electroretinograms were measured as a function of dietary supplements of purified ethyl esters of linolenic acid, linoleic acid, and oleic acid. Polyunsaturated fatty acids derived from precursors of linolenic and linoleic acids appear to be important functional components of photoreceptor cell membranes, although in equal dietary concentrations, linolenic acid precursors affect electroretinogram amplitudes to a greater extent than linoleic acid precursors. The electrical response of photoreceptor cell membranes appears to be a function of the position of the double bonds as well as a function of the total number of double bonds in fatty acid supplements.

Estrogen-Induced Uterine Responses and Growth: Relationship to Receptor Estrogen Binding by Uterine Nuclei11

Abstract: The relationship between estrogen receptor (R) binding by uterine nuclei and uterotrophic responses was examined. Immature rats received a single injection of estradiol (E2) or estriol (E3) and the following parameters were measured: accumulation and retention of the estrogen receptor by the nucleus of uterine cells; incorporation of 14C-glucose into CO2, lipid, protein and RNA; RNA polymerase activity; water imbibition and increased dry weight. E2 and E3 were of equal potency with regard to the rapid accumulation of R by the nucleus but differed with respect to long term retention of R. The concentrations of nuclear RE2 and RE3 complexes were equivalent between 1 and 3 hr after estrogen injection; however, by 6 hr RE2 remained significantly elevated while RE3 levels had fallen to control values. E2 and E3 were also of equal potency with respect to the stimulation of enhanced glucose utilization, water imbibition, the incorporation of 14C-glucose into lipid, protein and RNA 3 hours following an injection ...

Fate of Wastewater Bacteria and Viruses in Soil

Abstract: Bacterial survival in soil is affected by moisture content, temperature, organic matter, and antagonism by soil microflora In most instances the survival of bacterial pathogens in the soil is less than 2-3 months Removal of bacteria from sewage during percolation through the soil is accomplished largely at the soil surface by straining, sedimentation, and adsorption While relatively large numbers of bacteria and viruses appear to be removed through a few feet of soil under normal conditions, once they have gained entrance into the underground aquifer distances of travel as far as several hundred feet have been observed Removal of viruses by soil occurs largely by adsorption Salt concentration, pH, soil composition, organic matter, and the electronegativity of the virus and the soil may influence the degree of retention of viruses by the soil Viruses attached to soil particles can become deadsorbed with changes in water quality, resulting in greater subsurface travel Viruses survive at least as long as pathogenic bacteria in the soil

Progesterone antagonism of the oestrogen receptor and oestrogen-induced uterine growth

Abstract: PROGESTERONE has long been considered an antagonist of oestrogen action1. The delicate balance and interactions between these ovarian hormones are essential for many reproductive functions. Early studies in chick oviducts and uteri of rats and mice have shown that the simultaneous administration of progesterone and oestrogen resulted in inhibition or modification of oestrogen-induced growth of these target organs2–5. One possible mechanism by which progesterone could be antagonistic to oestrogen is by suppressing the quantity of cytoplasmic oestrogen receptor. It is generally held that the mechanism by which oestrogen, O, stimulates uterine growth depends on the binding of O to cytoplasmic receptors, Rc, to form RCO complexes6. These RCO complexes are translocated to nuclear sites where they probably stimulate nuclear events that cause the uterus to grow7. Translocation and nuclear accumulation of receptor–oestrogen complexes, RnO, are accompanied by a concomitant decrease in the quantity of Rc (ref. 8). During the period when Rc is reduced, the uterus is insensitive to additional exogenous oestrogen9. Gradually Rc is replenished by processes which may involve reutilisation and/or resynthesis8. Work from our laboratory indicates that the mechanism of action of non-steroidal oestrogen antagonists resides in their inability to stimulate the replenishment of the cytoplasmic oestrogen receptor, Rc, thereby rendering oestrogen responsive tissues less sensitive to oestrogen10,11. The possibility that progesterone might also act as an oestrogen antagonist by reducing the amount of oestrogen Rc has been suggested12,13. In this report, we demonstrate that progesterone does decrease the quantity of oestrogen receptors by interfering with the replenishment of Rc and that this decrease results in a reduced sensitivity of uterine tissue to oestrogen.

Microbiological hazards of household toilets: droplet production and the fate of residual organisms.

Abstract: Large numbers of bacteria and viruses when seeded into household toilets were shown to remain in the bowl after flushing, and even continual flushing could not remove a persistent fraction. This was found to be due to the adsorption of the organisms to the porcelain surfaces of the bowl, with gradual elution occurring after each flush. Droplets produced by flushing toilets were found to harbor both bacteria and viruses which had been seeded. The detection of bacteria and viruses falling out onto surfaces in bathrooms after flushing indicated that they remain airborne long enough to settle on surface throughout the bathroom. Thus, there is a possibility that a person may acquire an infection from an aerosol produced by a toilet.

Regulation of casein messenger RNA during the development of the rat mammary gland.

Abstract: Casein mRNA was isolated and partially purified from RNA extracts of rat lactating mammary glands and translated in a teterologous cell-free protein synthesizing system derived from wheat germ. Casein mRNA activity was assayed by immunoprecipitation using a specific antiserum prepared against a mixture of the purified rat caseins. Properties of rat casein mRNA were examined using a variety of sizing techniques, including chromatography on Sepharose 4B, sedimentation on sucrose gradients after heat denaturation, and electrophoresis on 2.5% agarose gels in 6 M urea. Casein mRNA activity was found in an 8-16S region after gradient centrifugation with the peak occurring at 10.5 S. In addition, the binding of rat casein mRNA to dT-cellulose was examined. Only 40% of the total casein mRNA activity was selectively retained. A partial purification of casein mRNA was accomplished by a combination of these sizing and affinity chromatography techniques. In the purified preparations casein mRNA activity comprises approximately 90% of the total mRNA activity. Characterization of this material by agarose gel electrophoresis revealed two main bands of RNA at approximately 12 and 16 S, both containing casein mRNA activity. These mRNAs were of the correct size to code for two of the principal rat caseins of approximately 25,000 and 42,000 molecular weights. Casein mRNA and total mRNA activities were then compared in total RNA extracts at various stages of normal mammary gland development in the rat, i.e. during pregnancy, lactation, and involution following weaning. A selective induction of casein mRNA activity compared to total mRNA activity was found to occur during pregnancy and lactation. Moreover, a selective loss of activity was also observed during mammary gland involution. A surprisingly high level of casein mRNA activity was found in RNA extracts from early and midpregnant mammary glands.

Androgen Binding Protein as a Biochemical Marker of Formation of the Blood-Testis Barrier

Abstract: Androgen binding protein (ABP) was measured during postnatal development in normal and irradiated rats to determine whether development of a blood-testis barrier and formation of a continuous lumen from testis to epididymis is correlated with entry of ABP into the caput epididymis. ABP is found in normal testis as early as 14 days postnatally (0.2 pmol/mg), at which time no blood-testis barrier is observed by the peroxidase perfusion technique. Previous findings have shown a close correlation of blood-testis barrier development and lumen formation. Indeed, ABP is not detectable in the epididymis until 18-20 days of age (1.0 pmol/mg) at which time blood-testis barrier formation and lumen development is complete. Whole body irradiation (125 rads) of pregnant rats at 19-20 days of gestation produces male offspring with seminiferous tubules remarkably free of germinal epithelium and containing essentially only Sertoli cells. These Sertoli cell-enriched (SCE) testes produce normal amounts of ABP between 14 and 21 days postnatally. However, between 21 and 30 days of age the specific activity of ABP is significantly higher in the SCE tests (2.8 pmol/mg protein) than in normal testis (0.5 pmol/mg protein). In the SCE testis neither blood-testis barrier development nor lumen formation are complete until 30 days of age, at which time ABP is first detectable in epididymis of the irradiated rat. Thereafter there is a gradual decline of ABP in the SCE testis-and a dramatic increase in the epididymis. NIH-FSH-S-10 (200 mug/rat) injected SC into 14-day-old normal rats stimulated ABP in the testis from control levels of 0.15 pmol/mg to 1.46 pmol/mg within 4 h after injection. However, no ABP was detectable in the epididymis of either the control or the FSH-stimulated rats. These findings suggest that entry of ABP into caput epididymis is an index of blood-testis barrier formation and lumen development.

Location of nucleolar organizers in animal and plant chromosomes by means of an improved N-banding technique

Abstract: With an improved N-banding technique, the location of nucleolar organizing region was determined in 27 kinds of material including mammals, a marsupial, birds, amphibians, fishes, an insect and plants. In most cases the N-bands were clearly located on certain specific regions of chromosomes, such as the secondary constriction, satellite, centromere, telomere and heterochromatic segment, while in some species they were detected as very minute bodies distributed over many chromosomes. From the available cytological and biochemical data it was suggested that the N-bands represent certain structural non-histone proteins specifically linked to nucleolar organizers in various eukaryotic chromosomes.

Echocardiographic determination of left ventricular stress-velocity relations.

Abstract: The time course of left ventricular (LV) circumferential stress and fiber shortening velocity (Vcf) were determined at 20 msec intervals in 30 patients from simultaneous recordings of LV pressure (micromanometer) and LV dimensions (echography). In 12 patients with normal LV function, endocardial and midwall maximal (max) Vcf, Vcf at peak stress, and endocardial mean Vcf were significantly greater than in eight patients with myocardial disease. Peak stress was less in the normal subjects (mean equal 241 gl/cm2, range 180 to 310 g/cm2) than in those with myocardial diseases (mean equals 371 g/cm2, range 280 to 513 g/cm2). Vcf was reduced in five out of seven patients with chronic LV volume overload, while peak stress ranged from normal in three to increased in four. Max Vcf, mean Vcf, and peak stress were normal in three patients with chronic LV pressure overload; Vcf at peak stress was normal in two. Good correlation was observed between angiographic determinations of mean Vcf and endocardial max Vcf, Vcf at peak stress and mean Vcf. Induced changes in preload in five patients (dextran infusion at constant heart rate) produced a 12.2 per cent increase in peak stress (P small than 0.05), and insignificant changes in max Vcf (3.7 per cent increase, P = NS), in Vcf at peak stress (5 per cent decrease, P smaller than 0.05), in mean Vcf (0.7 per cent increase, P = NS). Increasing afterload with angiotensin in seven patients (peak stress increased by 45 per cent, P smaller than 0.01) reduced max Vcf, Vcf at peak stress and mean Vcf by 33 per cent, 39 per cent respectively. Lowering afterload in one patient (amyl nitrite) produced an increase in Vcf. Improvement in Vcf was observed in all instances during positive inotropic stimulation (isoproterenol in three normals, digoxin in four with myocardial disease). Thre response of endocardial and midwall Vcf to loading and contractility were similar. In man Vcf is an index of myocardial contractility which is affected minimally by changes in preload but responds inversely to changes in afterload. Its sensitivity to acute afterload changes may, at times, limit its clinical applicability.

Increase in self-rejection as an antecedent of deviant responses.

Abstract: The hypothesis that increase in negative self-attitudes is an antecedent condition of deviant responses was tested. Subjects were seventhgrade students who responded to a questionnaire three times at annual intervals (N=3148). Self-attitudes were measured by a sevenitem self-derogation scale. Change in self-derogation was determined by expressing the posttest score as a deviation from the posttest-on-pretest regression line. For each of 22 deviant acts it was hypothesized and observed that, among students denying performance of the act prior to T2 T3, students affirming performance during T2 T3, relative to students continuing denial of performance, will have manifested significantly greater antecedent increases in self-derogation during T1 T2. The comparisons were significant in 19 of the 22 instances. The findings provide strong support for the position that the genesis of negative self-attitudes is a common influence mediating between adverse membership group experiences and the adoption of any of a wide variety of deviant responses.

Effect of particulates on virus survival in seawater.

Abstract: man pathogenic viruses whose fate in these waters is still incompletely understood. Outbreaks of infectious hepatitis have been traced to the consumption of shellfish taken from polluted marine waters,1 but epidem iological methods have not yet been de veloped enough for us to gain a complete understanding of the true extent of the transmission of viral disease by marine waters. This lack of information has placed additional emphasis on acquiring more fundamental knowledge about the fate of viruses in the marine environment.

Separation of polyunsaturated fatty acids by argentation thin layer chromatography.

Abstract: A single step, silver nitrate thin layer chromatographic procedure which separates a methyl ester mixture containing 0–6 double bonds is described. Purity of each ester recovered from the silver nitrate plate was 98–99%. Recovery of the esters ranged from 100% for saturates to 77% for pentaenes.

Lysyl oxidase deficiency in Ehlers-Danlos syndrome type V.

Abstract: Two maternal cousins affected by the X–linked form of Ehlers–Danlos syndrome have been observed. Both had congenital heart disease, “floppy valve syndrome”, hernias, short stature, stretchable skin and moderate joint hyper–mobility. Both excreted normal amounts of urinary glycosaminoglycans, almost entirely represented by dermatan sulfate, whose degradation appeared to be inadequate. They also excreted large amounts of hydroxylysine glycosides and L–valyl–proline, considered to be products of degradation of collagen and elastin, respectively. Cultured skin fibroblasts of the propositus synthesized excessively soluble collagen and had a low lysyl oxidase activity. These findings suggest that the increased degradation of structural proteins may be secondary to the defective cross–linking processes caused by the enzymic defect. Addition of (+) catechin, a flavonoid, to the propositus's cultured fibroblasts decreased the abnormal solubility of their collagen.

Maximal revascularization (reperfusion) in intact conscious dogs after 2 to 5 hours of coronary occlusion.

Abstract: Acute infarction was produced in intact conscious dogs by inflating a previously implanted balloon cuff around the left anterior descending coronary artery. The artery was occluded in 26 control dogs and reperfused by deflating the balloon cuff after 2 hours of occlusion in 19 dogs (group II) and after 5 hours in 11 dogs (group III). Serial studies were performed and repeated after 48 hours and 7 days. All three groups revealed hemodynamic and metabolic deterioration with coronary occlusion and infarct production. Immediately after reperfuslon, arrhythmias developed in groups II and III and persistent ventricular tachycardia was present 2 to 3 hours after reperfusion in 74 percent of animals in group II and 82 percent of those in group III compared with 6 percent and 13 percent incidence rates at corresponding times in control dogs. Q waves developed in 83 percent of animals in group II and 100 percent of those in group III but in only 12 and 27 percent of control animals at corresponding times. Hemodynamic deterioration was accelerated in the postreperfusion period in both groups II and III. Angiographic assessment revealed improvement in 42 percent of dogs in group II, but in none of those in group III after reperfusion. Myocardial oxygen extraction diminished to subnormal levels after reperfusion, indicating either reactive hyperemia or shunting effect. Mortality was not significantly influenced by reperfusion. Infarct size was more than 15 percent of ventricular mass in 92 percent of control dogs and in 100 percent of dogs in group III, but in only 50 percent of those in group II. The data indicate that reperfusion in conscious dogs representing early, noninvasive maximai revascularization under ideal circumstances fails to prevent deterioration or death; instead it hastens the development of arrhythmias and myocardial injury. Reperfusion, although deleterious in the first few hours, can reduce infarct size if performed after 2 hours, but not after 5 hours, of occlusion.

Localization patterns of plasma apolipoproteins in human atherosclerotic lesions.

Abstract: The localization patterns of human plasma lipoproteins and their respective apoproteins and of neutral lipid were determined in normal and atherosclerotic arteries. Specific antisera were prepared against plasma low-density lipoproteins(LDL) and their apoproteins (apoB), high-density lipoproteins(HDL) and one of their major apoproteins (apoA-I1, and apoC-III, which is a major apoprotein of very low-density lipoproteins (VLDL). Using immunofluorescence techniques, the various antigens were localized in arterial samples obtained at surgery or autopsy. The three apoproteins and neutral lipid were localized to the same tissue areas, namely, lipid core regions and certain connective tissue of atherosclerotic lesions, in 61% of the fibrous plaques and 48% of the fatty streaks examined. In marked contrast, none of the uninvolved arterial regions showed the presence of all four factors together. As controls, the localization of other serum proteins was also determined in these arteries using immunofluorescence techniques. Fibrinogen was associated with regions of maximum complementary localization of factors in 37% of the fibrous plaques and 64% of the fatty streaks. However, albumin was found in only 4-5% of these same regions. The present results suggest that not only LDL but also HDL and VLDL or their respective apoproteins as well as fibrinogen are specifically retained by certain tissue components of the atherosclerotic lesion.

Method and apparatus for recording activity in intact nerves

Abstract: A method and apparatus is provided which will attenuate bioelectric interference when measuring the activity in an intact nerve An electrode probe is provided having first and second electrodes positioned on opposite sides of a thin, flexible, insulating carrier The probe is inserted between the nerve to be measured and the underlying body tissue with one electrode contacting only the nerve and the second electrode contacting only the tissue The nerve and the tissue thereby form in effect a Wheatstone bridge about the carrier and the symmetrical electrodes which thus provides a nulling effect on extraneous electrical potentials, while a measurement of nerve potentials appearing as a voltage difference between the electrodes provides a measurement of activity in the nerve Additional, symmetrical pairs of electrodes may be positioned on the same carrier, and their outputs may electronically be combined for increasing the signal-to-noise ratio in the measurement The apparatus may also be implanted in a body by covering the first electrode and the portion of the nerve in contact with the electrode with a second insulator which is preferably bonded to the first insulator, the electrode carrier, for electrically isolating both the first electrode and the segment of nerve from surrounding tissues