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Biomedical subjects

S Smith

Publications and source records attributed to S Smith.

At least 703 records · Page 39Linked to original sources
PubMed1990

A "treated" model for severe hemorrhagic shock: a comparison of conventional and germ-free animals.

In an unanesthetized "treated" model of severe hemorrhagic shock, a bacteremia originating from the animal's enteric flora was demonstrated by finding radiolabeled Escherichia coli in the blood as early as 2 hr after the onset of shock. In 50 patients admitted to our trauma unit, the observation was similar, with 56% positive blood cultures, when their mean arterial blood pressure was 80 mmHg or less. The relationship of bacterial translocation and the high post-shock mortality in our conventional (CV) animal model is being evaluated in germfree (GF) Sprague-Dawley rats. Preliminary observations in 15 GF animals showed 80% survival at 24 hr post-shock, 54% at 48 hr, and 42% at 72 hr compared with those of CV animals in previous experiments with survival at similar times of 73%, 20% and 7%, respectively.

Animals↗
PubMed1990

Macromolecular adducts and related biomarkers in biomonitoring and epidemiology of complex exposures.

In order to evaluate the potential of biological markers in epidemiology and risk assessment of complex exposures, we review recent studies of macromolecular adducts and oncogene activation in human populations. Results are discussed in terms of the strengths and weaknesses of various study designs in order to identify the most promising approaches for future research.

Biomarkers, Tumor↗
PubMed1989

A young man with diabetes.

A diagnosis of diabetes seems catastrophic to most young people. Not only do they have to learn about the complexities of the disease, they also have to come to terms with the fact that their lifestyle has changed forever.

Adult↗
PubMed1989

Purification and characterization of CAF-I, a human cell factor required for chromatin assembly during DNA replication in vitro.

The purification and characterization of a replication-dependent chromatin assembly factor (CAF-I) from the nuclei of human cells is described. CAF-I is a multisubunit protein that, when added to a crude cytosol replication extract, promotes chromatin assembly on replicating SV40 DNA. Chromatin assembly by CAF-I requires and is coupled with DNA replication. The minichromosomes assembled de novo by CAF-I consist of correctly spaced nucleosomes containing the four core histones H2A, H2B, H3, and H4, which are supplied in a soluble form by the cytosol replication extract. Thus, by several criteria, the CAF-I-dependent chromatin assembly reaction described herein reflects the process of chromatin formation during DNA replication in vivo.

Biological Assay↗
PubMed1989

Assessment of the number of free cysteines and isolation and identification of cystine-containing peptides from acetylcholine receptor.

The number of free cysteines in each polypeptide of acetylcholine receptor from the electric organ of Torpedo californica has been assessed by alkylating the native protein with N-ethylmaleimide and iodoacetamide during homogenization of the tissue and alkylating the polypeptides with N-ethylmaleimide as they were unfolded in solutions of dodecyl sulfate. The cysteines unavailable for alkylation could be accounted for as specific cystines, connecting positions in the amino acid sequences of the individual polypeptides. Unreduced, alkylated polypeptides of acetylcholine receptor were digested with thermolysin or trypsin. Cystine-containing peptides in the chromatograms of the digests were identified electrochemically by the use of a dual gold/mercury electrode. Three thermolytic peptides and three tryptic peptides have been isolated from these digests and shown to contain intact cystines that were originally present in the native protein. The majority of these peptides contained an intact, intramolecular cystine connecting two cysteines in locations homologous to cysteines 128 and 142 from the alpha polypeptide. Each of these cystines from each of the polypeptides of acetylcholine receptor was isolated in at least one peptide, respectively. Each of these cystine-containing peptides also contained glucosamine. It can be concluded that each asparagine in the sequence Asn-Cys-Thr/Ser, which occurs in the respective, homologous location in every polypeptide, is glycosylated even though a cystine sits between the asparagine and the threonine or serine. In addition, the existence of the cystine connecting the adjacent cysteines, alpha 192 and alpha 193, in the alpha subunit of acetylcholine receptor [Kao, P. N., & Karlin, A. (1986) J. Biol. Chem. 261, 8085-8088] has been confirmed.

Amino Acid Sequence↗
PubMed1989

T lymphocyte cytotoxicity with natural varicella-zoster virus infection and after immunization with live attenuated varicella vaccine.

Varicella-zoster virus (VZV) specific cytotoxicity was investigated during acute primary VZV infection, in naturally immune subjects and after vaccination with the live attenuated varicella vaccine by using T cell cultures (TCC) generated by stimulating PBMC with VZV Ag and autologous VZV-superinfected lymphoblastoid cell lines as targets. Lysis of VZV-infected lymphoblastoid cell lines was observed by TCC from acutely infected subjects, naturally immune subjects, and recipients of the varicella vaccine. VZV glycoprotein I induced cytotoxic T cells but killing was less efficient than killing by TCC stimulated with VZV Ag. The TCC were primarily CD4+ (mean 86.6%) T lymphocytes with 15.2% of the cells coexpressing Leu-19. TCC were predominantly restricted by HLA class II as demonstrated by lack of any blocking using class I mAb and blocking of 15 to 71% by L243, a mAb to class II. Unrestricted killing as measured by killing of K562 cells occurred in all TCC but was minimally greater than that observed against uninfected autologous targets. Phenotypes of PBMC during acute infection had an initial increase in CD4+ cells and an overall decrease in the percentage of circulating Leu-11+ (CD16). No enhanced K562 killing was demonstrated in PBMC from subjects with acute infection compared to subjects without infection. CD4+ CTL may function as an important primary host response in acute varicella. Immunization with live attenuated varicella vaccine induced VZV-specific, memory CTL responses comparable to those of naturally immune subjects. The demonstration of their persistence long after primary VZV infection may indicate a role for CTL in restriction of viral replication during episodes of VZV reactivation from latency.

Adult↗
PubMed1989

White blood cell response to uphill walking and downhill jogging at similar metabolic loads.

The object of this study was to determine whether leukocytosis would occur in response to eccentric exercise, to concentric exercise, and/or to possible increases in serum cortisol levels. Eight men performed 2 bouts of exercise at 46% VO2max for 40 min. Subjects initially walked up a 10% grade (UW); 2 weeks later they jogged down a 10% grade (DJ), a form of eccentric exercise known to induce delayed onset muscle soreness (DOMS). Venous blood samples were drawn before and after each exercise bout (0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, and 5 h). Total and differential WBCc and serum cortisol levels were assessed. Results were analyzed using repeated measures ANOVA (2 x 11). Subjects experienced severe DOMS after DJ. There was a significant difference in TWBCc (p less than 0.0001) between UW and DJ. Post-hoc testing revealed no significant increase over baseline values for UW; after DJ there was a 46% increase over baseline values (p less than 0.05) initially seen at 1.0 h. These increases in TWBCc were predominantly a reflection of increases in neutrophils which were significant (p less than 0.0001) when compared to baseline values at 1.0, 1.5 and 2.0 h (approximately 60%). No significant neutrophil increases were seen after UW. Cortisol levels were similar for both groups pre-exercise (UW = 367.1 +/- 38.6, DJ = 320.2 +/- 44.16 nmol.L-1 means +/- SE) and decreased similarly for both groups after exercise, and thus were not related to the post-exercise neutrophilia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Intercellular signaling as visualized by endogenous calcium-dependent bioluminescence.

Bioluminescence in the hydrozoan coelenterate Obelia results from calcium activation of a photoprotein contained in light-emitting cells (photocytes) scattered in the animal's endoderm. The influx of calcium into nonluminescent endodermal cells through conventional voltage-dependent calcium channels is required for the excitation-luminescence coupling. Our results suggest that the subsequent diffusion of this calcium, via gap junctions, into the neighboring photocytes triggers a localized luminescence response. Following intense stimulation, the local rise in calcium elicits a secondary wave of luminescence that is supported by a voltage-independent calcium permeability mechanism in the photocyte plasma membrane. These two mechanisms for elevating internal calcium in light-emitting cells can account for the spatial and temporal features of intracellular luminescence in Obelia.

Animals↗