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S Sacks

Publications and source records attributed to S Sacks.

At least 37 records · Page 2Linked to original sources
PubMed1995

Repeatability and validity of a field kit for estimation of cholinesterase in whole blood.

OBJECTIVES: To evaluate a spectrophotometric field kit (Test-Mate-OP) for repeatability and validity in comparison with reference laboratory methods and to model its anticipated sensitivity and specificity based on these findings. METHODS: 76 farm workers between the age of 20 and 55, of whom 30 were pesticide applicators exposed to a range of organophosphates in the preceding 10 days, had blood taken for plasma cholinesterase (PCE) and erythrocyte cholinesterase (ECE) measurement by field kit or laboratory methods. Paired blinded duplicate samples were taken from subgroups in the sample to assess repeatability of laboratory and field kit methods. Field kits were also used to test venous blood in one subgroup. The variance obtained for the field kit tests was then applied to two hypothetical scenarios that used published action guidelines to model the kit's sensitivity and specificity. RESULTS: Repeatability for PCE was much poorer and for ECE slightly poorer than that of laboratory measures. A substantial upward bias for field kit ECE relative to laboratory measurements was found. Sensitivity of the kit to a 40% drop in PCE was 67%, whereas that for ECE was 89%. Specificity of the kit with no change in mean of the population was 100% for ECE and 91% for PCE. CONCLUSION: Field kit ECE estimation seems to be sufficiently repeatable for surveillance activities, whereas PCE does not. Repeatability of both tests seems to be too low for use in epidemiological dose-response investigations. Further research is indicated to characterise the upward bias in ECE estimation on the kit.

Adult↗
PubMed1995

Beneficial effects of oxfenicine on the hypoxic rat atria.

During hypoxia the isolated rat atria released lactate into the bathing medium and underwent a rise of resting tension and a decline of the peak developed tension and pacemaker frequency. The atria from 24 h fasted rats, which oxidize faster their endogenous triacylglycerol pool, showed greater functional disturbances during hypoxia and a smaller recovery after reoxygenation than those from fed rats. Oxfenicine, which is a selective inhibitor of carnitine palmitoyltransferase I, attenuated the rise of resting tension and improved the post-hypoxic recovery of peak tension in the atria from fasted rats. The decline of the pacemaker frequency as well as the lactate output were not altered by the inhibitor. Present data show that oxfenicine ameliorated some of the hypoxic functional disturbances. Inasmuch lactate output did not change and these effects manifested only in the atria predisposed to the utilization of endogenous lipids, it may be inferred that oxfenicine preserved the atrial functions through the inhibition of fatty acid oxidation.

Animals↗
PubMed1995

Effects of L-carnitine on the hypoxic atria from fed and fasted rats.

The aim of the investigation was to assess whether L-carnitine, an essential cofactor in the mitochondrial transfer of fatty acids, would ameliorate the hypoxic-induced disturbances in the isolated rat atria. During hypoxia, the atria released lactate into the bathing medium and underwent a rise in resting tension and a decline of the peak developed tension and pacemaker frequency. The atria from 24-h fasted rats, which oxidize faster their endogenous triacylglycerol stores>> exhibited greater functional disturbances during hypoxia and a smaller recovery after reoxygenation, with respect to the fed rats' atria. Furthermore, at the end of the hypoxic incubation the fasted rats atria displayed a reduction of the free CoA content together with a 3-fold increase in the content of long-chain fatty-acyl CoA, in comparison with those of fed rats. The addition of 5 mM L-carnitine 60 min before the onset of hypoxia did not exert any effect on the hypoxic atria. In contrast, 20 mM L-carnitine accelerated the decline of the pacemaker activity in the fasted rat atria and worsened the contracture development in both nutritional states. The fall of the peak tension and the posthypoxic recovery as well as the levels of free CoA and long-chain fatty-acyl CoA, and lactate output, were not affected by 20 mM L-carnitine treatment. These data suggest that L-carnitine is not beneficial for the hypoxic rat atria, even in the fasted state, wherein the atrial fatty acid catabolism is increased.

Animals↗
PubMed1993

C3 and C4 gene expression and interferon-gamma-mediated regulation in human glomerular mesangial cells.

The glomerular mesangial cell (GMC) plays a key role in the maintenance of glomerular structure and function and in the mediation of glomerular injury. To explore the potential of this cell to produce complement and react to local inflammatory signals, we studied the synthesis and regulation of the third and fourth components of complement in cultured human GMC. Using metabolic labelling and immunoprecipitation, we found that C3 and C4 polypeptide chains were synthesized and secreted by GMC. Interferon-gamma (IFN-gamma) led to an increase in C4 protein synthesis, but not C3 synthesis. There was a corresponding increase in C4 mRNA in IFN-gamma-activated cells, but no increase in C3 mRNA, as determined by semi-quantitative polymerase chain reaction (PCR) estimation. These results demonstrate that human GMC can synthesize C3 and C4 proteins, and that regulation of expression of the C4 gene is mediated by IFN-gamma. We hypothesize that GMC production of complement could influence the clearance of immune aggregates by the kidney and the mediation of glomerular injury.

Base Sequence↗
PubMed1993

Pharmacokinetics of rufloxacin in patients with impaired renal function.

The pharmacokinetics of rufloxacin were investigated in normal subjects and in patients with various degrees of renal failure after the administration of a single oral 400-mg dose. Twenty-four subjects were classified by glomerular filtration rate (GFR) normalized for body surface area. Group 1 subjects had GFRs of > 80 ml/min, group 2 subjects had GFRs from 30 to 80 ml/min, group 3 subjects had GFRs from 8 to 29 ml/min, and group 4 subjects had GFRs of < 8 ml/min. The patients in group 4 were on continuous peritoneal dialysis or underwent hemodialysis 48 h after dosing. Plasma and urinary rufloxacin concentrations were determined by high-performance liquid chromatography. A two-compartment model was used to calculate rufloxacin pharmacokinetic parameters. Apparent total body clearance of the drug was linearly related to GFR (r = 0.696; P < 0.01). The elimination half-life increased proportionally with the severity of renal impairment, with values of 30 +/- 3, 36 +/- 5, and 44 +/- 3 h in groups 1, 2, and 3, respectively. In patients with moderate renal failure, dosage adjustment of rufloxacin is not needed. The rufloxacin dose interval should be prolonged to 48 h as the GFR falls below 30 ml/min/1.73 m2.

Adult↗
PubMed1992

Recombinant alpha-2 interferon gel treatment of recurrent herpes genitalis.

Topical recombinant alpha-2 interferon treatment of recurrent genital herpes was studied in a randomized, double-blind, placebo controlled clinical trial. Three hundred and eighty-seven patients were treated at eight study centers with either interferon gel or placebo four times daily for four days. Interferon therapy caused a 26% decrease in the duration of viral shedding. For male patients, there were also significant decreases in the time to crusting (17%) and duration of pain (34%) and itching (21%). For patients with recurrent genital herpes, treatment with topical interferon was found to be effective in decreasing the duration of viral shedding and, for males, pain, itching and time to crusting.

Administration, Cutaneous↗
PubMed1991

Inhibition of pyruvate dehydrogenase complex (PDHC) by antipsychotic drugs.

The effects of 11 antipsychotic drugs on the pyruvate dehydrogenase complex (PDHC) prepared from bovine heart and rat brain were investigated. All inhibited PDHC to varying extents. With clinically equivalent doses, chlorpromazine and thioridazine inhibited the most and fluphenazine and thiothixene the least. The relationship of degree of inhibition of PDHC by neuroleptics to clinical improvement of 32 outpatients treated with acetazolamide and thiamine (A + T) ancillary therapy for chronic mental illness suggests that patients treated with psychoactive drugs that inhibit PDHC the least are most likely to have a favorable response with A + T treatment.

Acetazolamide↗
PubMed1991

Effect of acetate on blood metabolites and glucose tolerance during haemodialysis in uraemic non-diabetic and diabetic subjects.

We examined changes in blood concentrations of glucose, acetate and other blood intermediary metabolites as well as the disposal of an intravenous glucose load during successive glucose-free acetate and control bicarbonate haemodialysis in random order, in non-diabetic and diabetic subjects. Plasma acetate levels increased about 10-fold in both the diabetic and non-diabetic subjects during the 1st hour of acetate dialysis. This was accompanied by about 5-fold increase in the levels of the ketone bodies-acetoacetate and 3-hydroxybutyrate. Ketone body levels did not change during bicarbonate dialysis. Additionally, the changes in blood levels of glucose, non-esterified fatty acids, pyruvate, lactate, glycerol and insulin were similar with either bicarbonate or acetate treatment in each subject group. The KG rate constant of glucose disposal after intravenous glucose (10 g/m2 body surface area) given after the 1st hour of a 5-hour haemodialysis was similarly unchanged with acetate or bicarbonate dialysis, despite the additional caloric load likely from the high blood levels of acetate obtained during acetate haemodialysis. We conclude that the major metabolic effect of acetate during haemodialysis is an increase in blood ketone body levels. Glucose utilisation, as assessed from the KG rate constant of glucose disposal or changes in blood lactate and pyruvate levels, was not affected by the high acetate levels attained during dialysis.

Acetates↗
PubMed1990

Design of a 13C (1H) RF probe for monitoring the in vivo metabolism of [1-13C]glucose in primate brain.

The design of an RF probe suitable for obtaining proton-decoupled 13C spectra from a subhuman primate brain is described. Two orthogonal saddle coils, one tuned to the resonant frequency of 13C and the other to the resonant frequency of 1H, were used to monitor the in vivo metabolism of [1-13C]glucose in rhesus monkey brain at 2.1 T. Difference spectra showed the appearance of 13C-enriched glutamate and glutamine 30 to 40 min after a bolus injection of [1-13C]glucose.

Animals↗
PubMed1990

Population decentralization within metropolitan areas: 1970-1980.

Using a data set that maintains geographic and fiscal continuity over time and across a sample of major U.S. metropolitan areas, the authors identify factors of economic and population decentralization that affected central city areas between 1970 and 1980. The problems of annexation are resolved by estimating population changes for central cities and suburban areas with constant 1980 boundaries, and by calculating fiscal variables from overlapping jurisdictions by city area as opposed to municipal city government only. "The empirical investigation supports the view that demographic and housing stock variables seem to have had a greater impact on decentralization than central city-suburban fiscal differences."

Americas↗
PubMed1989

Amino acid analysis using 1-naphthylisocyanate as a precolumn high performance liquid chromatography derivatization reagent.

A method which uses 1-naphthylisocyanate as an HPLC precolumn derivatization reagent for amino acid analysis is described. Derivatization is carried out by adding the isocyanate dissolved in dry acetone to a buffered amino acid solution followed by extraction of the excess reagent with cyclohexane. The resulting naphthylcarbamoyl amino acids are stable and highly fluorescent, with excitation maxima at 238 and 305 nm and an emission maximum at 385 nm, for most amino acids. Ultraviolet detection near 222 nm, the absorption maximum, can also be employed. HPLC procedures permitting the analysis of protein hydrolysates, brain extract, cerebrospinal fluid, and blood plasma are presented. The method is particularly suitable for auto-sampler procedures since samples can be derivatized and diluted in advance and stored at room temperature in the sampler while awaiting injection. Other advantages include high sensitivity, the possibility of recovering the derivatives from the column effluent, and the absence of a reagent peak in the chromatograms.

1-Naphthylisothiocyanate↗
PubMed1988

Transformations of maps to investigate clusters of disease.

An approach is presented to display and analyze epidemiologic data using population density equalized maps (cartograms). The algorithm for generating these maps is discussed. A specific method for statistically analyzing plotted data is given, followed by an application of maps and analysis to 73 sets of age-, race-, sex-, and site-specific cancer incidence data. The data were obtained from the Surveillance, Epidemiology and End Results project for San Francisco City/County (1978-1981) and combined with 1980 U.S. Census data.

Adult↗
PubMed1988

Correction of late glottic insufficiency.

Preservation of respiration, deglutition, and phonation, as well as tumor ablation, is the objective of conservation surgery of the larynx. Immediate reconstruction may fail, leading to aspiration and aphonia. Five extralaryngeal techniques for correction of late glottic insufficiency are described.

Cricoid Cartilage↗
PubMed1988

Total hip arthroplasty in Gaucher's disease. Long-term prognosis.

Avascular necrosis of the femoral head is a cause of morbidity in patients with Gaucher's disease. Total hip arthroplasty (THA) is recommended, but there is controversy about the long-term value of this procedure. In eight patients treated with 15 THAs, 11 (73%) have remained fully mobile and asymptomatic up to 14 years following surgery. These long-term follow-up observations are evidence in favor of THA for treatment of hip joint problems associated with Gaucher's disease.

Adult↗