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Biomedical subjects

S L Goldstein

Publications and source records attributed to S L Goldstein.

11 recordsLinked to original sources
PubMed1997

Hemodialysis catheter survival and complications in children and adolescents.

Venous catheters have become an indispensable form of hemodialysis access. We evaluated catheter performance as temporary and long-term access in children with end-stage renal disease (ESRD). We assessed the survival rates and causes of catheter failure in 78 catheters used for hemodialysis access in 23 pediatric patients (aged 10 months to 22 years) with ESRD over a 5-year period. Median survival was 31 days for 56 uncuffed catheters. One- and 2-month actuarial survival was 69% and 48%, respectively. Reasons for removal were: elective (39%), kinking (36%), trauma (11%), infection (7%), and other (5%). Smaller catheters (7 or 9 French) were more likely to be removed for kinking (P = 0.003). One-year actuarial survival for 22 cuffed catheters was 27%. Cuffed catheters were removed due to: infection (36%), kinking (14%), elective (9%), trauma (9%) and other (9%). Twelve catheters were removed for infection. Infection rates leading to removal were 0.58 and 0.71 per patient-year for uncuffed and cuffed catheters, respectively. Staphylococcus species were cultured most commonly. We conclude that uncuffed catheters function well for short-term hemodialysis access of up to 2 months' duration and cuffed catheters are successful for long-term access in children and adolescents with ESRD.

Adolescent↗
PubMed1996

Determination of isotope enrichments of magnesium in microwave-digested biological samples by thermal ionization mass spectrometry using a direct loading technique.

The isotope ratios of magnesium were determined in isotopically normal and 26 Mg-enriched samples of human blood, blood plasma, urine and faeces and bovine muscle. The measurements were made with a magnetic sector, thermal ionization mass spectrometer (TIMS) equipped with a multiple ion collector system for simultaneous detection of the ion currents. The samples were decomposed using microwave digestion with HNO3 and HCI. Without further chemical treatment, the mineralized samples were deposited together with silica gel and boric acid on rhenium filaments, which served as thermal ionization source filaments. This method, called the direct loading technique (DLT), results in stable ion signals of the magnesium isotopes with isotope ratios indistinguishable from those of natural Mg standards within experimental error. Fractionation-corrected 26 Mg/24 Mg ratios of natural Mg standards were determined with a relative external precision of 0.02%. The magnesium recoveries for all of the analysed matrices were > or = 97%; 26 Mg was added to calibrated sample solutions to produce isotopic enrichments within a range typically appearing in samples of human tracer studies. Linear regression analysis of measured versus expected per 1000 (/1000) enrichments yields y = 0.998x + 0.79. The DLT described here is a simpler and quicker method than other methods reported hitherto. It has the advantage of avoiding magnesium separation and purification steps prior to TIMS analysis for all of the analysed biological samples and thus reduces contamination and guarantees optimum magnesium recovery. The reported method improves the applicability of stable isotopes of magnesium in human tracer studies.

Animals↗
PubMed1996

Alpha 3 beta 1 integrin has a crucial role in kidney and lung organogenesis.

A mutation was targeted to the murine alpha3 integrin gene. Homozygous mutant mice survived to birth, but died during the neonatal period. The mutation caused abnormal kidney and lung development. Mutant kidneys displayed decreased branching of the medullary collecting ducts, although the number of nephrons was not altered. Proximal tubules exhibited two distinct subsets of abnormalities, with the epithelial cells either containing excess lysosomes or becoming microcystic. In addition, glomerular development was markedly affected. In mutant kidneys, the extent of branching of glomerular capillary loops was decreased, with capillary lumina being wider than normal. The glomerular basement membrane was disorganized and glomerular podocytes were unable to form mature foot processes. Branching of the bronchi in lungs of mutant mice was also decreased and the large bronchi extended to the periphery. These results indicate a role for integrin receptors in basement membrane organization and branching morphogenesis.

Animals↗
PubMed1983

Metabolite distribution and rate of residue clearance in turkeys fed a diet containing aflatoxin B1.

The retention of aflatoxin residues in tissues of turkey poults fed a diet containing aflatoxin B1 (500 ppb) for 18 days was determined. Free and conjugated aflatoxin metabolites were quantified using high-pressure liquid chromatography. Aflatoxin residue levels were greater in liver than muscle tissues, although all levels were low (range 0.01-1.19 ng/g tissue). Free and conjugated aflatoxins B1 and M1, a metabolite of B1, were the principal tissue residues. Other metabolites investigated included aflatoxicol, which was detected in certain samples, and aflatoxin Q1 which was not detected. Conjugated aflatoxins, hydrolysed and extracted from the aqueous tissue fractions, comprised 55-91% of the total detected aflatoxin residues. All aflatoxin residues were rapidly cleared following discontinuation of the dietary aflatoxin B1 (half-life 1.4 days for total aflatoxin clearance from liver). These results provide further evidence that tissues from animals maintained on diets containing aflatoxins do not provide a major source of aflatoxins when consumed by man.

Aflatoxin B1↗
PubMed1975

Investigations concerning the mode of action of 3,4-dihydroxybutyl-1-phosphonate on Escherichia coli.

Experiments were performed to evaluate the ability of the enzymes of Escherichia coli involved in glycerol 3-phosphate metabolism to recognize phosphonic acid analogues of the natural substrate. Neither the catabolic membrane-bound glycerol-3-phosphate dehydrogenase nor the acyl coenzyme A: glycerol-3-phosphate acyltransferase can use 3,4-dihydroxybutyl-1-phosphnate or 2,3-dihydroxypropyl-1-phosphonate are inhibitors of the reduction of dihydroxyactone phosphate as substrates. The 4-carbon phosphonic acid analogue does not exhibit inhibitory activity for either of these enzymes. While the 3-carbon phosphonic acid analogue has no inhibitory effect upon the catabolic dehydrogenase, it does appear to have a slight but reproducible inhibitory effect on the acyltransferase. Glycerol 3-phosphate and 3,4-dihydroxybutyl-1-phosphonate by glycerol 3-phosphate:NAD (P) oxidoreductase. rac-2,3-Dihydroxypropyl-1-phosphonate does not appear to be recognized by this enzyme. The apparent K-i for snglycerol 3-phosphate is 19 muM and for D-3,4-dihydroxybutyl-1-phosphonate it is 42 muM. In addition the glycerol 3-phosphate:NAD(P) oxidoreductase catalyzes the reduction of 4-hydroxy-3-oxobutyl-1-phosphonate (apparent K-m of 182 muM), a phosphonic acid analogue of dihydroxyacetone phosphate. 3,4-Dihydroxybutyl-1-phosphonate is both a competitive inhibitor (apparent Ki of 740 muM) and a substrate (apparent K-m of 450 muM) for the CDP-diglyceride: glycerol 3 phosphate phosphatidyltransferase but it has no effect upon CDP-diglyceride:L-serine phosphatidyltransferase. The relationship ofthese in vitro studies to in vivo investigations is discussed.

Acyltransferases↗