Showing papers by "University of Colorado Denver published in 1969"

Antimicrobial Agents and Membrane Function

Abstract: Publisher Summary This chapter explains the interactions of antibiotics (and antimicrobial agents generally) with cellular membranes, and the application of these reagents to the study of membrane physiology in micro-organisms. Much of the experimental material currently available refers to mitochondria and to artificial membrane systems, perhaps because biochemists were alert to the selective effects of many antibiotics on membrane functions. The chapter is restricted to those functions, which appear to be intrinsically associated with membranes: impermeability to small molecules, active transport, and the generation of metabolic energy. Eucaryotic cells, such as fungi and algae, differ fundamentally from the procaryotic bacteria in the organization of membranous elements. In the former, the plasma membrane serves as the main osmotic barrier and energy generation is the function of specialized organelles, mitochondria, and chloroplasts. In procaryotic cells, the division of labor is much less obvious. Exposure of bacteria to certain compounds—including organic solvents and detergents, destroys the osmotic barrier. This is readily recognized by release from the cells of small metabolites such as K+, phosphate, amino acids and sugars, and is generally lethal. The concept that ions traverse membranes in association with lipid-soluble carriers is traditional in membrane physiology, but it been recognized recently that certain pharmacological agents exert their effects by serving as artificial ion carriers.

Energy Coupling in the Transport of β-Galactosides by Escherichia Coli: Effect of Proton Conductors

Abstract: Escherichia coli accumulates thiomethyl-β-d-galactoside against a concentration gradient under anaerobic conditions. The accumulation was abolished by carbonylcyanide m-chlorophenylhydrazone, tetrachlorosalicylanilide, 2,4 dinitrophenol, and other uncouplers of oxidative phosphorylation even though oxidative phosphorylation would not be expected to occur anaerobically. In the presence of the uncouplers, the β-galactoside carrier remained functional and catalyzed equilibration of thiomethylgalactoside across the membrane. The uncouplers did not inhibit the generation of adenosine triphosphate or protein turnover, or the accumulation of α-methylglucoside and glycerol by phosphorylation. We conclude that, at least anaerobically, uncouplers of oxidative phosphorylation do not interfere with energy metabolism in general, but prevent the utilization of metabolic energy for the active transport of galactosides. The uncouplers also facilitate passage of protons across the membrane. Various hypotheses are considered to explain why a proton-impermeable membrane may be required for active transport of galactosides and other substrates.

Synovectomy and débridement of the knee in rheumatoid arthritis. II. Clinical and roentgenographic study of thirty-one cases.

Abstract: 1. The results of twenty-eight synovectomies and debridements in adults and three synovectomies in children are discussed. Eighty-five per cent of the procedures in adults were performed in late stages of destruction. All adult patients had classic rheumatoid arthritis with multiple joint involvement. Seventy-nine per cent of the knees were rated improved by the patient as compared with 65 per cent rated improved by the examiner. In 46.5 per cent definite or probable recurrence was found. 2. The results and the incidence of recurrence were found to be time dependent and proportional to the general activity of the disease as well as to the extent of damage present at the time of operation. When synovectomy was done bilaterally at an identical stage of the disease, the results were comparable. 3. Scoring of a patient's disability and local disease activity were found to be very useful in order to evaluate the results quantitatively. 4. Joint instability and joint narrowing were used as the criteria of the extent of joint damage and were found to be reliable in predicting the chances of success of synovectomy in a patient with low or moderate disease activity. 5. Angular deformity, antedating rheumatoid involvement, tends to progress rapidly with the onset of arthritis and should probably be corrected early. 6. Recurrence does not always become apparent during the first few months after synovectomy. 7. In advanced stages of destruction the objective of synovectomy is temporary relief of pain and functional improvement. Synovectomy alone is not indicated when there is severe instability and loss of articular cartilage. 8. Synovectomy is strongly indicated for a knee which has shown persistent involvement of short duration when there is advanced joint destruction of the opposite knee. 9. With early mobilization, the range of motion is not significantly affected and does not correlate with the final subjective and objective result in most patients. 10. Only two complications occurred: one a separation of the patellar tendon and the other, thrombophlebitis.

Followup evaluation of family crisis therapy.

Abstract: Six-month followup evaluations of 150 family crisis therapy cases and 150 hospital treatment cases demonstrate that those treated as outpatients do as well as the hospital cases. Social functioning is maintained equally in both groups. Patients are less likely to be rehospitalized if admission was avoided initially.

The pediatric nurse practitioner in the office of pediatricians in private practice

Abstract: The experience of a two-man pediatric practice with a pediatric nurse practitioner indicates that this is an economically sound means of partially relieving the immediate manpower shortage and of improving medical care to children. The pediatric nurse practitioner provides skill and competent services to patients and their parents which is well accepted by them. Having the pediatric nurse practitioner in the office is an economic asset. She is a valuable associate in managing a variety of day-to-day problems. Her presence has resulted in an increase in the number of patients seen and an overall improvement of services provided.

Osteogenesis imperfecta: effect of magnesium administration on pyrophosphate metabolism.

Abstract: The bone collagen of human osteogenesis imperfecta is a potent inhibitor ofin vitro calcification. The inhibition was removed by treatment of the collagen with pyrophosphate in the presence of magnesium ions. Elevated levels of serum and urinary inorganic pyrophosphate were found in 28 patients with osteogenesis imperfecta. Oral administration of magnesium oxide or magnesium sulfate to four of these patients significantly reduced their serum and urinary levels of pyrophosphate.

Report on the Hearing Screening of 17.000 Neonates

Abstract: (1969). Report on the Hearing Screening of 17.000 Neonates. International Audiology: Vol. 8, No. 1, pp. 72-76.

The effect of fetal exchange transfusions with adult blood upon fetal oxygenation.

Abstract: Extract: Intrauterine exchange transfusions were conducted in fetal sheep using adult sheep as donors. Indwelling catheters in the fetus permitted sampling of blood for 8 to 36 days following the transfusion. In the first days after the procedure there was a decreased oxygen affinity of umbilical blood, an increase of about 5 mm Hg in umbilical venous O2 tension, and a decrease of about 30% in O2 saturation. In the following weeks there was a gradual return of O2 affinity, PO2, and oxygen saturation to normal. In all of the experiments there was a good correlation between the O2 affinity of umbilical blood and the percentage of adult cells present. This correlation indicated that adult cells retained a normal O2 dissociation curve even after weeks of exposure to the new environment. Despite an increased umbilical venous PO2, the fetal reticulocyte count increased significantly after transfusion, but the oxygen capacity of umbilical blood remained within normal limits. Speculation: These studies suggest that the correction of fetal anemia in erythroblastosis fetalis by the use of fetal blood instead of adult blood would produce a greater increase in the amount of hemoglobin capable of carrying oxygen at the low oxygen tensions characteristic of the fetal circulation.

Hepatic Disorders in Renal Homograft Recipients.

Abstract: Liver damage in renal homotransplant recipients is more common than is generally believed. It occurred in 60% of 146 patients studied and was severe in 13.7 %. Common causes of liver damage are viral hepatitis and/or the use of immunosuppressive and other potentially hepatotoxic drugs. The incidence of major liver complications has been less since the introduction of horse antihuman-lymphocyte globulin as an adjuvant immunosuppressive agent.

Secretion from the cortex-free bovine adrenal medulla.

Abstract: 1. The isolated bovine adrenal medulla was prepared from whole glands by careful removal of the cortex. The tissue was perfused with physiological salt solution and stimulated with a variety of secretogogues.2. Catecholamines were secreted from the tissue upon stimulation with carbamylcholine, nicotine sulphate, acetylcholine bromide, histamine dihydrochloride, (+)-amphetamine sulphate and potassium chloride.3. Carbachol-induced secretion of catecholamines was reduced in the presence of either hexamethonium bromide or tetracaine hydrochloride, during perfusion with calcium-free perfusion fluid, or during perfusion at low temperature.4. Stimulation of the medulla with carbachol also led to secretion of chromaffin granule protein and acid deoxyribonuclease. The relationships between catecholamines secreted and the amounts of these proteins secreted were similar to the corresponding values for the perfused whole bovine adrenal gland. Perfusate lactate dehydrogenase activity and perfusate haemoglobin content were unchanged after carbachol stimulation.5. It is concluded that there are no differences in the mechanisms for catecholamine secretion from the cortex-free perfused medulla and the perfused whole gland.

Red cell aldolase deficiency in hereditary spherocytosis.

Abstract: Summary: Red cell aldolase activity decreases normally with cell age at a mathematically predictable rate. Compared to aldolase activity so predicted for red cells of the same age, activity of this glycolytic enzyme was 35 per cent deficient (range 18–53 per cent) in 20 splenectomized patients from eight unrelated families with typical hereditary spherocytosis. In two unsplenectomized patients with hereditary spherocytosis red cell age was estimated from measurement of their diisopropyl-fluorophosphate (DF32P)-labelled red cell survivals, and deficiencies of 62 and 55 per cent in red cell aldolase activity observed. The rates of glycolysis in intact cells and haemolysates measured under conditions designed to produce maximum rates of lactate formation were 20–30 per cent less than expected for the red cell age in the splenectomized subjects. Since patients with hereditary spherocytosis are probably heterozygous for the genetic defect presumed to be present in this disease, the magnitude of deficiency was compared to those reported in heterozygotes for inherited red cell abnormalities such as sickle haemoglobinopathy, glucose-6-phosphate dehydrogenase deficiency and pyruvate kinase deficiency and it was found to be similar. This suggests that a deficiency in red cell aldolase activity may be the basic biochemical lesion in hereditary spherocytosis. One of the products of the aldolase reaction, dihydroxyacetone phosphate, is known to be an important precursor for phospholipid in other tissues, suggesting a possible relationship between red cell aldolase deficiency and the known red cell membrane abnormalities of hereditary spherocytosis.

Critical Arginine Residue for Maintaining the Bacteriophage Tail Structure

Abstract: The addition of 0.2 m l-arginine to various T-even bacteriophage preparations inactivated the virus preparations irreversibly. The virus particles were even more sensitive to added d-arginine and l-homoarginine than to l-arginine but were unaffected by arginine analogues with either an altered carboxyl group or guanidyl group. Treatment of phage T2H with 2,3-butanedione, a reagent which specifically reacts with the guanidyl portion of arginine residues, resulted in the apparent in-activation of most of the virus particles. However, after incubation of the treated particles at pH 7.5 at 37 C for 1 hr in the absence of butanedione, the original virus titer almost completely returned. The reactivation was completely inhibited by the presence of 0.2 m d-arginine. It appeared that the virus protein coat was sufficiently plastic so that the initial conformational change resulting from the alteration of an arginine residue (to possibly an ornithine residue) was at least partially reversible and that the virus tail proteins then refolded to produce a stable and active virus particle. These reactivated virus particles were not sensitive to inactivation by d-arginine but could now be rapidly inactivated by l-ornithine. Virus particles inactivated by arginine have altered tail structures. They have contracted tail sheaths still attached to tail plates and still contain tail cores. These properties of virus particles indicate that there is a free carboxyl group and a guanidyl group spatially equivalent to an arginine residue on one component of the virus tail which bind reversibly by means of polar linkages to another tail component. These bonds maintain the integrity of the virus tail. Added arginine appears to compete with this endogenous viral arginine for the binding sites and then to favor an irreversible conformational change.

Steady-State Concentrations of Glucose-6-Phosphate, 6-Phosphogluconate, and Reduced Nicotinamide Adenine Dinucleotide Phosphate in Strains of Escherichia coli Sensitive and Resistant to Catabolite Repression

Abstract: No correlation was found between the cellular steady-state concentrations of glucose-6-phosphate, 6-phosphogluconate, and reduced nicotinamide dinucleotide phosphate and resistance versus sensitivity to catabolite repression.