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Biomedical subjects

J Weiss

Publications and source records attributed to J Weiss.

At least 487 records · Page 27Linked to original sources
PubMed1976

Reversible envelope effects during and after killing of Escherichia coli w by a highly-purified rabbit polymorpho-nuclear leukocyte fraction.

The effects of a highly-purified, potently bactericidal fraction from rabbit polymorphonuclear leukocytes on the envelope of Escherichia coli (W) have been examined. This leukocyte fraction has equally enriched bactericidal, permeability-increasing and phospholipase A2 activities, and is essentially devoid of lysozyme, myeloperoxidase and protease activities (Weiss, J., Franson, R.C., Beckerdite, S., Schmeidler, K. and Elsbach, P. (1975) J. Clin. Invest. 55, 33-42). Rapid killing of E. coli by this fraction is accompanied by two almost immediate alterations in the bacterial envelope: (1) a discrete increase in envelope permeability (measured by inhibition of bacterial leucine incorporation by normally impermeant actinomycin D), and, (2) hydrolysis of 14C-labeled fatty acid-prelabeled E. coli phospholipids. Both envelope effects are promptly reversed during further incubation at 37 degrees C, But not at 0 degrees C, with 40 mM Mg2+. Reversal is also produced by Ca2+ (40 mM) and trypsin (200 mug/ml), but 200 mM K+ causes only partial recovery and Na+ and hyperosmolar sucrose are ineffective. Upon addition of Mg2+, phospholipid degradation ceases abruptly and the labeled products of hydrolysis (free fatty acids and lysocompounds) disappear with a corresponding reaccumulation of radioactive diacylphosphatides. The time course of resynthesis of phospholipids coincides with that of restoration of the permeability barrier. Higher concentrations of the leukocyte fraction and prolonged incubation increase both the extent of phospholipid degradation and the time required for reversal of both envelope effects. These findings suggest that both the initiation of the increased permeability and its reversal are linked to respectively the breakdown and resynthesis of major E. coli membrane phospholipids, and thus depend on the fact that the biochemical apparatus of E. coli remains capable of biosynthesis despite loss of viability. Treatment of E. coli, exposed to the leukocyte fraction, with albumin results in extracellular sequestration of the products of hydrolysis and also restores the permeability barrier to actinomycin D, suggesting that the accumulation of lytic products of lipid hydrolysis within the bacterial envelope, rather than the loss of phospholipids per se, causes increased permeability Whereas the effects on the envelope are reversible as long as 2 h after nearly complete loss of ability to multiply by E. coli, the effect on bacterial multiplication is irreversible within 5 min.

Animals↗
PubMed1976

Drug-induced parkinsonism in the rat- a model for biochemical investigation of the parkinson-syndrome. III. The incorporation of D-glucose-14C(U) in amino acids of brain and liver from rats pretreated with reserpine or with phenothiazines.

Following treatment with reserpine or alternatively with a combination of phenothiazines (Randolektil, Majeptil) a drug-induced parkinsonoid reaction was provoked in rats. Twenty min before decapitation, 18 muCi d-glucose-14C(U) was administered intravenously. Concentration and radioactivities of glutamic acid (glu), glutamine (gln), serine (ser), and glycine (gly) were assayed in some regions of brain and in liver. Separation was performed by a combination of paper electrophoresis and chromatography or by an automatic amino acid analyzer. 1 After reserpine, the concentrations of serine and glycine were increased ten-fold while their specific activities decreased by the same factor. The interconversion serine-glycine was not affected. The concentration of glutamic acid was reduced while its specific activity remained constant. 2. After phenothiazines, the concentrations of serine and glycine in brain were also increased but their specific activities were decreased to a different degree. This indicates an additional effect on the serine-synthesis from glucose. The interconversion serine-glycine was also altered. The concentration of glutamic acid was decreased but specific activity was constant except in the thalamus region tested. 3. The influence of both treatments on amino acid turnover in liver differed from the observed impairment of brain metabolism. 4. Possible correlations between the changes in amino acid metabolism, catecholamines, and the neurologic parkinsonian symptoms are discussed.

Amino Acids↗
PubMed1976

Electromechanical properties of the single cell-layered heart of tunicate Boltenia ovifera (sea potato).

The tubular heart of the sea potato is composed of a single layer of myoepithelial cells interconnected near the extraluminal surface by specialized junctions. If these junctions are used as the border which separates the luminal from extraluminal membrane, the surface area ratio, luminal:extraluminal, is approximately 12:1. A single myofibril is located near the luminal surface in each cell. Current passed across the heart wall in the direction that depolarizes the luminal membrane and hyperpolarizes the extraluminal membrane immediately produces "all-or-none" action potentials and contractions. Current passed in the opposite direction fails to produce action potentials until after the break of the stimulus, suggesting anodal break excitation of the hyperpolarized luminal membrane. High potassium solutions depolarized the myoepithelium and produced contractions only when applied to the luminal surface of the heart. [Ca]0 increases and [Mg]0 decreases twitch tension only on the luminal surface of the heart. The transwall resistivity is low (50-100 omega/cm2) due to an extracellular shunt. Because of this shunt and the larger surface area of the luminal membrane, the extraluminal membrane is effectively clamped to the potential of the luminal membrane and is not capable of directly influencing excitation-contraction coupling. These findings suggest that only the luminal membrane of the sea potato myoepithelium is capable of generating an action potential and triggering contraction.

Action Potentials↗
PubMed1976

[The influence of neuroleptic drugs on urinary excretion of non-protein nitrogen (author's transl)].

During treatment with thioxanthenes or phenothiazines of schizophrenic patients non-protein nitrogen in urine was measured. The values were calculated in relation to the excretion of creatinine. a) Flupentixol or fluphenazine applied in optimal dosage, increased the excretion of urea and the amino acids asp, glu + gln, and gly. b) Moreover, if the drug induced a parkinsonoid (thioridazine) the excretion of ser and thr was increased, too. The usual desalting procedure by ion-exchanging resins before chromatography increases the contents of several amino acids, e.g. asp, asn, ala, gly, cys, ser, thr, indicating a breakdown of some instable products.

Amino Acids↗
PubMed1975

[The activity of aminotransferases in serum and cerebrospinal fluid in neurological diseases (author's transl)].

The activities of the aminotransferases, GOT and GPT, were determined in the serum and cerebrospinal fluid of patients with Parkinson's disease, Huntington's chorea, Wilson's disease, amyotrophic lateral sclerosis (ALS), Friedreich's ataxia, phenylketonuria, and head injuries. 1. In patients with Huntington's chorea the activity of SGOT was lower than in controls (P = 0.02); in Friedreich's ataxia LGPT activity was decreased (P less than 0.001); in patients suffering from ALS SGOT (P = 0.005), SGPT (P less than 0.001) and LGOT (P less than 0.001) activities were increased. 2. Long-term treatment of Parkinson's disease and Wilson's disease with L-dopa resulted in an increase in SGOT, LGOT, and SGPT activity over approximately 2 months, with subsequent normalization of these enzyme activities in spite of continued therapy. Guanidine treatment led to an increase in aminotransferase activities in patients with ALS. Penicillamine caused a decrease in SGOT and SGPT activities in Wilson's disease. These results illustrate the necessity of taking therapeutic measures into account in the interpretation of data on aminotransferase activities.

Alanine Transaminase↗
PubMed1975

[The effect of acetylsalicylic acid, extremely restricted movement and a cholesterol-rich diet on atheromatosis of the rabbit aorta: comparative investigations (author's transl)].

A multifactorial model for demonstrating the pathogenesis of the diet-induced atheromatosis of the rabbit is described. We examined the effect of various diets (atherogenetic, rich in fibre, mixed, normal) and of extreme restriction of movement, with and without doses of acetylsalicylic acid. The aorta showed uniforms morphological findings; 1. Acetylsalicilic acid no influence on the cholesterol-induced atheromatosis of the rabbit; 2. An atherogenic diet and a diet rich in raw fibre caused different degrees of sclerosis of the aorta; this was related to the cholesterol content of the mixed diet, which was 50% less than the cholesterol content of the atherogenic diet; 3. Macro- and microscopic examination showed that extreme restriction of movement alone has no demonstrable effect on the aorta of the rabbit; 4. The cholesterol-induced atheromatosis showed significantly less involvement of the aorta when there was extreme restriction of movement in addition to the diet; 5. In none of the test groups could we demonstrate any effect of PAT I on platelet adhesiveness; 6. The test conditions did not result in an activation of the contact phase of the haemocoagulation system.

Animals↗
PubMed1975

Partial characterization and purification of a rabbit granulocyte factor that increases permeability of Escherichia coli.

Recently we reported that rapid killing of Escherichia coli by granulocytes or granulocyte fractions is accompanied by an equally rapid and discrete increase in permeability of the microbial envelope (Beckerdite, Mooney, Weiss, Franson, and Elsbach. 1974. J. Exp. Med. 140: 396-409). Most of this permeability-increasing activity (PI) is found in a crude granule preparation. PI is quantitatively recovered in a 23,000-g supernatant fraction (Sup II) after sulfuric acid extraction of granulocyte homogenates prepared in water. PI is nondialyzable, destroyed by pronase and trypsin, stable at 4degreesC for at least 2 mo, and destroyed by heating at 94degreesC. Anionic substances, such as heparin sulfate and isolated E. coli lipopolysaccharide, bind to and inhibit PI. PI has been purified up to 1,000-fold from homogenate in a yield of 50percent by acid extraction and carboxymethyl-Sephadex chromatography. Such purified fractions have bactericidal activity that equals that of disrupted granulocytes and Sup II, are similarly enriched with respect to granule-associated phospholipase, and protease activities. Whereas E. coli, sensitive to PI, binds or inactivates solubilized PI, a resistant strain of Serratia marcescens does not. Binding of PI to sensitive microorganisms seems to be necessary for expression of its biological activity since both the apparent binding to and the biological effect of PI on E. coli are completely blocked by 10-20 mM Mg2+ or Ca2+. Mg2+ or Ca2+ can reverse the effect on E. coli permeability produced by Sup II or the carboxymethyl-Sephadex fraction but not that produced by granulocyte homogenate. The close association of bactericidal, phospholipase A2, and permeability-increasing activities towards several gram-negative bacterial species suggests that they may be related.

Animals↗