Search PubMed⌕ Search

Biomedical subjects

S Fischer

Publications and source records attributed to S Fischer.

At least 451 records · Page 25Linked to original sources
PubMed1983

Physicochemical characterization of a fast refolding monomeric class I fructose-1,6-bisphosphate aldolase from Staphylococcus aureus.

The class I fructose-1,6-bisphosphate aldolase from Staphylococcus aureus is proposed as a good candidate for thermodynamic and kinetic studies on protein folding. The monomeric enzyme (molecular weight 35 000 +/- 1000) has been previously described as 'unusually heat-stable' [F. Götz et al. (1980) Eur. J. Biochem. 108, 295-301]. In the present paper we show that the enzyme is reversibly denatured at relatively low temperature (26-39 degrees C), as determined by protein fluorescence and far ultraviolet circular dichroism; the van't Hoff enthalpy of the thermal unfolding is 355 +/- 63 kJ/mol. The dichroic absorption shows that the aldolase is extensively unfolded in 6 M guanidine/HCl. Complete reactivation of the guanidine-denatured enzyme in the test solution is extremely fast (less than 10 s in the temperature range from 24.6 degrees C to 7.7 degrees C). Reactivation ought to be much slower if isomerization reactions around at least some of the ten Xaa-Pro peptide bonds were rate-limiting for reactivation.

Animals↗
PubMed1983

Prostacyclin metabolism in adults and neonates. Urinary profiles of 6-ketoprostaglandin F1 alpha and 2,3-dinor-6-ketoprostaglandin F1 alpha studied by gas chromatography-mass spectrometry.

Metabolism of endogenous prostacyclin was studied in adults and neonates by measuring urinary levels of 6-ketoprostaglandin F1 alpha (spontaneous hydrolysis product) and 2,3-dinor-6-ketoprostaglandin F1 alpha (enzymatically formed by beta-oxidation). Quantification of prostanoids was achieved by capillary gas chromatography-mass spectrometry using the stable isotope dilution technique. Purification of the urinary lipid extract included silicic acid column chromatography and reverse- and straight-phase high-pressure liquid chromatographies. Accuracy of the method was proven by recovery experiments for both metabolites. Partial mass spectra of endogenous 6-ketoprostaglandin F1 alpha and 2,3-dinor-6-ketoprostaglandin F1 alpha were obtained from urine samples. In neonates (third day of life, n - 5 pooled urines) levels of 2,3-dinor-6-ketoprostaglandin F1 alpha (0.28 +/- 0.18 ng/ml) were much lower than those of 6-ketoprostaglandin F1 alpha (2.13 +/- 1.10 ng/ml), indicating low beta-oxidation activity at high prostacyclin formation. In adults (n = 7), levels of 2,3-dinor-6-ketoprostaglandin F1 alpha (0.27 +/- 0.21 ng/ml) and levels of 6-ketoprostaglandin F1 alpha (0.20 +/- 0.11 ng/ml) were about the same, indicating relatively high beta-oxidation at low prostacyclin formation. Values are expressed as mean +/- S.D.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

Neurofilament architecture combines structural principles of intermediate filaments with carboxy-terminal extensions increasing in size between triplet proteins.

Mammalian neurofilament triplet proteins (68 K, 160 K and 200 K) have been correlated by a biochemical, immunological and protein chemical study. The 160 K and 200 K triplet proteins are intermediate filament proteins in their own right, since they reveal the alpha-helical coiled-coil rod domain analyzed in detail for the 68 K protein. Triplet proteins display two distinct arrays. Their amino-terminal region built analogously to non-neuronal intermediate filament proteins should allow a co-polymerization process via the interaction of coiled-coil domains. The extra mass of all triplet proteins is allocated to carboxy-terminally located extensions of increasing size and unique amino acid sequences. These may provide highly charged scaffolds suitable for interactions with other neuronal components. Such a domain of 68 K reveals, in sequence analysis, 47 glutamic acids within 106 residues. The epitope recognized by a monoclonal antibody reacting probably with all intermediate filament proteins has been mapped. It is located within the last 20 residues of the rods, where six distinct intermediate filament proteins point to a consensus sequence.

Amino Acid Sequence↗
PubMed1983

Inhibition of prostaglandin I2 (PGI2) formation by LDL-cholesterol or LDL-peroxides?

A hypothesis of Gryglewski et al. explains the correlation between increased level of LDL and development of atherosclerosis by inhibition of PGI2 synthesis by increased peroxide content of LDL. The aim of the present paper was to examine this hypothesis. The major results are: 1) Preparation of LDL in the presence of .02% butylated hydroxytoluene did not reduce the lipid peroxide content of LDL from men and women and not change the inhibition or stimulation of the in vitro biosynthesis of PGI2 by LDL isolated from blood of men or women, respectively. 2) In the LDL and HDL, respectively, of healthy men we found nearly the same lipid peroxide levels (nmole malondialdehyde (MDA)/mg lipoprotein-cholesterol) as in the lipoproteins of male patients with hyperlipidemia type IIa or IV, but the peroxide concentration is three times higher in HDL as in LDL. 3) LDL isolated from healthy men inhibited in dose dependent fashion the generation of PGI2 from PGH2 by aortic microsomes whereas LDL from premenopausal women stimulated PGI2 formation even calculated as LDL lipid peroxides (in nM MDA/ml). The results call into question the hypothesis that diminished PGI2 formation by atherosclerotic vessels is related to inhibition of PGI2 synthetase by lipid peroxides present in LDL in the lesions. A new working hypothesis is presented that also the fatty acid pattern and the lipid class composition in the LDL are important for their influence on the PGI2 formation.

Animals↗
PubMed1983

Comparison of imported with locally retrieved kidneys preserved by intracellular electrolyte flushing followed by cold storage.

Ice-cold intracellular electrolyte flushing followed by cold storage and economy air shipment is the cheapest method to share kidneys for transplantation. This study from 1 center compares 62 primary cadaver kidney grafts imported from other centers to 128 that were retrieved locally. Cold ischemia time was 36.4 plus or minus 8.6 hours (mean plus or minus standard deviation) in the imported group and 24.2 plus or minus 8.8 hours in the locally retrieved group. The significant increase in first week dialysis (71 versus 42 per cent) and 1-month serum creatinine nadirs (2.63 plus or minus 2.73 versus 1.78 plus or minus 1.04 mg./dl.) was explained by longer cold ischemia times in the imported kidney grafts. There were no significant differences between the 2 groups with respect to actuarial kidney graft survivals and serum creatinine levels at 1, 2 and 3 years. Intracellular electrolyte flushing followed by simple cold storage and air transportation provides kidney graft survivals and long-term kidney graft function at minimal expense when the kidneys are retrieved from beating-heart cadavers and have undergone minimal warm ischemia.

Cold Temperature↗
PubMed1983

Successful human kidney preservation by intracellular electrolyte flush followed by cold storage for more than 48 hours.

Transplantation of cadaver kidneys after flushing with an ice-cold intracellular electrolyte solution is inhibited by arbitrary time limits on cold ischemia. During the 25-month interval ending March 22, 1982 we transplanted 7 kidneys preserved by this method and cold-stored for 48.2 to 61.4 hours. Of the recipients 86 per cent required dialysis within 1 week after transplantation, the mean serum creatinine nadir within 1 month was 2.1 mg./dl. and the graft survival at 1 month was 71 per cent. The 1-year actuarial cadaver graft survival was 69.2 plus or minus 18.1 per cent. Kidneys preserved by this simple method can be transplanted successfully after 48 hours of simple cold storage.

Cold Temperature↗
PubMed1983

Transitional cell carcinoma of the renal collecting tubules ("renal urothelioma").

Carcinoma of the renal collecting tubules is presented, for the first time in the literature, by a systematic description of 18 renal specimens from cases with or without pelvis carcinoma. The study revealed a surprisingly high incidence of carcinoma in the collecting tubules in association with carcinoma of the pelvis (20%), but as a primary tumour, independent of the pelvic growth. In cases of invasive extension, it is also possible to distinguish between the two localizations of carcinoma by histological criteria. The finding of papillary structure, umbrella cells with keratohyaline or parakeratosis demonstrates that we are dealing with a carcinoma originating in the urothelium of the collecting tubules ("renal urothelioma") corresponding entirely to carcinomas of the urinary tract. In a modification of the WHO histological grading of urinary tract tumours, the frequency of grades, I, II, and III is stated for urothelioma and pelvis carcinoma. Perusal of the 18 case records, on the other hand, did not divulge conclusive data as to whether smoking or the use/abuse of analgesics had been operative as carcinogenic factors.

Aged↗
PubMed1983

Platelet function, thromboxane formation and blood pressure control during supplementation of the Western diet with cod liver oil.

Epidemiologic and experimental data suggest an antiatherothrombotic potential of omega-3 polyunsaturated fatty acids. Therefore, the Western diet, which supplies predominantly omega-6 polyunsaturated fatty acids, was supplemented with 40 ml/day of cod liver oil, which provides about 10 g of omega-3 polyunsaturated fatty acids daily, for 25 days in eight volunteers. The omega-3 polyunsaturated fatty acids were incorporated in platelet and erythrocyte membrane phospholipids at the expense of omega-6 polyunsaturated fatty acids. Bleeding time increased (p less than 0.01) and platelet count (p less than 0.05), platelet aggregation upon ADP and collagen (p less than 0.01-0.05), and associated thromboxane B2 formation (p less than 0.01) decreased. Blood pressure (p less than 0.05) and blood pressure response to norepinephrine (p less than 0.01) and angiotensin II (NS) fell, without major changes in plasma catecholamines, renin, urinary aldosterone, kallikrein, prostaglandins E2 and F2 alpha and red cell cation fluxes. Biochemical and functional changes were reversed 4 weeks after cod liver oil was discontinued. Formation of prostaglandins derived from eicosapentaenoic acid and interference of eicosapentaenoic acid with formation and action of prostaglandins derived from arachidonic acid were evident in vitro. Whatever the mechanism, this moderate supplement of omega-3 polyunsaturated fatty acids markedly changed membrane phospholipids, which was associated with a shift toward less reactive platelets and a blunted circulatory response to pressure hormones.

Adult↗
PubMed1983

A comparison of work activities of mental health professionals among disciplines and environments.

Due to fiscal constraints on health care providers, the utilization of time of mental health professionals has come under close examination. The authors conducted a study of the work habits of 193 psychiatrists, psychologists, nurses, rehabilitation therapists, social workers, and mental health workers in 1976 and 1977. The clinicians worked at 18 facilities that offered inpatient, outpatient, partial hospital, or a mix of partial and outpatient services. Their work activities were observed over a two-week period. The data were analyzed for each clinical type and for each service modality across three funding sources--state, private, and mixed. The data, in part, show that a substantial amount of time was spent in all types of facilities in indirect patient care activities, particularly use of psychiatric records. Privately funded inpatient facilities devoted a much greater amount of time to direct patient care than did state inpatient facilities, which spent more time on administration and use of records. Staff of outpatient or partial-mixed facilities spent much more time on individual or other therapies, while inpatient staff spent more time on patient management and informal contacts with patients.

Ambulatory Care↗
PubMed1982

Amino acid sequence around the active site of two class I fructose-1,6-bisphosphate aldolases from staphylococci.

The amino acid sequences of a 26-residue segment containing the active-site lysyl residue of the class I fructose-1,6-bisphosphate aldolases from Staphylococcus aureus and Staphylococcus epidermidis have been determined. The sequence homology within the active sites between these enzymes and those from several eucaryotic class I aldolases showed a maximum of 21%. The similarity may indicate the origin of both procaryotic and eucaryotic class I aldolases from a common ancestor.

Amino Acid Sequence↗
PubMed1982

Prostacyclin metabolites, in urine or adults and neonates, studied by gas chromatography-mass spectrometry and radioimmunoassay.

Endogenous levels of two metabolites of prostacyclin, 6-keto-prostaglandin F1 alpha (spontaneous hydrolysis product) and 6,15-diketo-13,14-dihydroprostaglandin F1 alpha (enzymatic degradation product) were measured in urine of adults and neonates by gas chromatography-mass spectrometry, using deuterated internal standards. The method comprised extraction of prostanoids by reverse-phase cartridges and purification by silicic acid column chromatography and reverse-and straight -phase high-performance liquid chromatographies. Exogenous 6-keto-prostaglandin F1 alpha and 6,15-diketo-13,14-dihydroprostaglandin F1 alpha added to urine were recovered quantitatively by gas chromatography-mass spectrometry. Endogenous levels of 6-keto-prostaglandin F1 alpha in urine of adults were 0.11 +/- 0.05 (S.D.) ng/ml (n = 12), whereas in urine of neonates the levels were much higher: 1.41 +/- 0.36 (S.D.) ng/ml (n = 5) on the 3rd day of life declining to 0.51 +/- 0.21 (S.D.) ng/ml (n = 5) on the 5th day. 6-keto-prostaglandin F1 alpha was also estimated in both age groups by radioimmunoassay. Urinary levels of 6,15-diketo-13, 14-dihydroprostaglandin F1 alpha in neonates on the 3rd day of life were 2.12 +/- 0.70 (S.D.) ng/ml (n = 4) and declined until the 5th day. In adult urine this metabolite was below the limit of detection (0.20 ng/ml).

6-Ketoprostaglandin F1 alpha↗
PubMed1982

High level of tyrosine protein kinase in a murine lymphoma cell line induced by Moloney leukemia virus.

Several sarcoma-inducing viruses encode protein kinases that phosphorylate tyrosine residues. Such enzymatic activities can be detected within the detergent-insoluble matrix of transformed fibroblasts. We have analysed the protein kinase activities in two murine lymphoma cell lines ( MBL2 and LSTRA) induced by Moloney murine leukemia virus (Mo-MuLV). After incubation of the detergent-insoluble matrix of these cells with [gamma-32P]ATP, several alkali-resistant phosphoproteins, including a very heavily labelled 55 000 mol. wt. protein ( p55 ), have been detected in LSTRA, reflecting the activity of a protein kinase specific to this cell line. This protein kinase activity shares some of the distinctive properties of the protein kinases of transforming viruses, i.e., specificity for tyrosine residues, association with membranous and/or cytoskeletal structures, and inhibition by a synthetic peptide derived from the phosphorylation site of pp60src. In view of the absence of a transforming gene in MoMuLV , it is likely that the high level of protein kinase detected in the LSTRA cell line arises from the expression of a cellular gene.

Amino Acids↗
PubMed1982

Gastric malignancy: ten year experience at a community teaching hospital.

A ten-year review of gastric malignancy was undertaken and several factors examined. The degree of organ involvement played a significant role in determination of survival. Surgical resection, either palliative or curative, was associated with a more favorable short-term survival and bypass alone appeared to add nothing to patient survival time. The general lack of symptoms in early gastric cancer appears to be a majority determinant of the advanced state of malignancy in these patients. Early screening may represent a partial solution to this dilemma.

Adenocarcinoma↗
PubMed1982

Analysis of 6-keto-prostaglandin F1 alpha in human urine: age-specific differences.

A radioimmunoassay (RIA) for the estimation of 6-keto-PGF1 alpha in human urine is described in detail. The RIA method was validated by direct comparison to gas chromatography-mass spectrometry. In adults and in one year old children basal excretion of 6-keto-PGF1 alpha was found to be lower than that reported for PGE2 or PGF2 alpha. However, during the first week of life, significantly more 6-keto-PGF1 alpha was excreted. The very high levels of 6-keto-PGF in urine seen on the third day of life seemed already to decrease during the first week of life. It is concluded that prostacyclin may have a major role for kidney function in the newborn, possibly by protecting the immature kidney from high levels of angiotensin II.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Attempts to infect plant protoplasts with Toxoplasma gondii.

The interaction of tachyzoites of Toxoplasma gondii with plant protoplasts was compared with their interaction with cultures of HeLa cells. Unlike the HeLa cells, the plant protoplasts were refractory to invasion under all conditions tested. The lack of invasion was not an artefact of the protoplast isolation technique. This is the first description of a cell type refractory to Toxoplasma invasion; hence possible mechanisms for the specificity of parasite-host cell interaction can now be studied.

Cellulase↗