PubMed Health⌕ Search

Biomedical subjects

D L Williams

Publications and source records attributed to D L Williams.

At least 19 recordsLinked to original sources
PubMed1992

A pilot study of dried blood spot testing for HIV antibody in neonates.

An unlinked anonymous HIV antibody study of neonates, using surplus dried blood spots on Guthrie cards, was introduced as a means of estimating the prevalence of HIV infection in childbearing women. From March 1990 to February 1992, blood spots from 14,520 infants were tested for anti-HIV, using an HIV IgG antibody capture particle-adherence test; only one sample gave a confirmed positive reaction. This type of study involves no interference in routine care and can be operated without difficulty in a district general hospital setting where neonatal metabolic screening is performed.

AIDS Serodiagnosis↗
PubMed1992

DNA hybridization analysis of mycobacterial DNA using the 18-kDa protein gene of Mycobacterium leprae.

DNA hybridization studies using a 611-base pair (bp) probe, encoding the entire 18-kDa protein of Mycobacterium leprae, demonstrated that M. simiae, M. intracellulare, M. kansasii, M. terrae, ADM-2, M. avium, M. scrofulaceum, M. gordonae and M. chelonei appear to possess DNA sequences homologous to the 18-kDa protein gene of M. leprae. RFLP analysis revealed that the restriction sites in the M. leprae 18-kDa gene were not conserved in the putative gene homologs of M. simiae and M. intracellulare. The restriction patterns observed with the 611-bp probe were useful in differentiating M. intracellulare, M. simiae, and M. leprae from each other, as well as in distinguishing strains of M. simiae serovar 1. Finally, the presence of homologous sequences in various mycobacteria did not affect the specificity of a previously described PCR test for detection of M. leprae, based on the M. leprae 18-kDa protein gene.

Bacterial Proteins↗
PubMed1992

Association between synthesis and release of cGMP and nitric oxide biosynthesis by hepatocytes.

Hepatocytes are known to synthesize nitric oxide (NO) from L-arginine via an inducible NO synthase. Studies were performed to determine the relationship between hepatocyte NO production and the stimulation of hepatocyte soluble guanylate cyclase. A combination of lipopolysaccharide (LPS), interferon-gamma, tumor necrosis factor, and interleukin-1 stimulates the biosynthesis of large quantities of nitrite and nitrate (NO2- + NO3-). Hepatocyte NO2- + NO3- production was associated with only small increases in intracellular guanosine 3',5'-cyclic monophosphate (cGMP) levels but much greater increases in extracellular cGMP release over an 18-h time period. This cGMP synthesis was dependent on the L-arginine concentration and was inhibited in a reversible manner by NG-monomethyl-L-arginine. The cytokines or LPS added alone induced small increases in nitrogen oxide production and concomitant minor elevations in cGMP release. Atrial natriuretic peptide also stimulated the release of cGMP by hepatocytes which appeared to be independent of the cytokine+LPS-induced cGMP release. The addition of probenecid reduced the cGMP release by 66%, while cell damage was excluded as a cause for the extracellular release. Addition of 3-isobutyl-1-methylxanthine, but not M&B 22948, increased hepatocyte intra- and extracellular cGMP levels after cytokine+LPS stimulation. Induction of nitrogen oxide synthesis by hepatocytes in vivo by injecting rats with killed Corynebacterium parvum resulted in increased cGMP levels in freshly isolated hepatocytes and increased cGMP release by the hepatocytes when placed in culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Differential regulation of apolipoprotein-E messenger RNA in zona fasciculata cells of rat adrenal gland determined by in situ hybridization.

Previous studies showed that apolipoprotein-E (apoE) mRNA is regulated in rat adrenal gland by treatments that alter adrenal gland cholesterol content and steroidogenesis. In the present study cell types expressing apoE mRNA were determined by in situ hybridizations using an [alpha-35S]UTP-labeled RNA probe. Autoradiographic grains were counted to compare apoE expression in adrenal glands from control and experimentally treated animals. In control adrenal gland, zona (z.) fasciculata and z. reticularis exhibited the highest level of apoE mRNA expression, with lower levels in z. glomerulosa and medulla. Dexamethasone (DEX) treatment selectively increased apoE mRNA 3-fold in outer z. fasciculata, but not in other adrenal zones. ApoE mRNA expression appeared to be lower in adrenal glands from 4-aminopyrazolopyrimidine-treated rats, in that differences among adrenal gland zones were abolished. DEX treatment increased adrenal gland cholesteryl ester and oil red O staining in z. fasciculata cells in which the apoE mRNA concentration was increased as well as in other cortical cells in which apoE mRNA was unchanged. Aminoglutethimide administration led to a large increase in oil red O staining throughout the cortex, including z. fasciculata, without affecting apoE mRNA expression. These data suggest that adrenal gland apoE mRNA expression is not closely coupled to cellular cholesterol concentrations. Increased apoE mRNA expression in z. fasciculata of DEX-treated animals suggests an inverse relationship between apoE mRNA concentration and the level of steroidogenesis. This result is consistent with the proposal that apoE may play a role in regulating the utilization of cholesterol for steroid production.

Adrenal Glands↗
PubMed1979

Comparative tumor-inhibitory and anti-bacterial activity of soluble and particulate glucan.

A soluble fraction of particulate glucan was prepared and evaluated for its anti-tumor and anti-bacterial activity. Thin-layer chromatographic analysis indicated that the soluble preparation was composed of a variety of polyglucoses. Intravenous administration of soluble or particulate glucan resulted in significant reductions in the growth of a syngeneic anaplastic mammary carcinoma and melanoma B16. Survival data demonstrated that intravenous administration of soluble or particulate glucan prolonged survival of A/J and C57BL/6J mice with subcutaneous tumor implants. As regards to bacterial infections, soluble and particulate glucan decreased renal necrosis in S. aureus challenged mice as compared to control mice. Although the exact nature of the active soluble fraction(s) of glucan remains to be delineated, these studies demonstrate that a soluble glucan preparation exhibits significant anti-tumor and anti-staphylococcal activity. The active soluble fraction of particulate glucan may be preferable to particulate glucan in view of the inherent ease of parenteral administration.

Animals↗
PubMed1979

Apoproteins of avian very low density lipoprotein: demonstration of a single high molecular weight apoprotein.

The high molecular weight apoproteins of very low density lipoprotein (VLDL) were compared after preparation of VLDL from plasma and sera of diethylstilbestrol-treated roosters. When prepared from plasma with adequate control of endogenous proteolytic activity, VLDL contained a single high molecular weight apoprotein (apo-VLDL-B) as judged by electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate. Serum VLDL contained multiple apoprotein species, the largest of which corresponded to apo-VLDL-B. Immunological analyses showed that the multiple apoproteins of serum VLDL were quantitatively and qualitatively indistinguishable from plasma apo-VLDL-B. These data indicate that apo-VLDL-B can be cleaved during VLDL isolation to produce an apparent heterogeneity of high molecular weight apoproteins. The molecular weight of plasma apo-VLDL-B was estimated to be 350 000. This protein was stable to reduction and S-carboxymethylation and showed no association with apo-VLDL-II [Chan, L., Jackson, R.L., O'Malley, B. W., & Means, A.R. (1976) J. Clin. Invest. 58, 368] through disulfide linkage. Apo-VLDL-B and apo-VLDL-II represented 54% and 46%, respectively, of the total VLDL protein recovered following gel filtration chromatography in sodium dodecyl sulfate. Protein recovery in the chromatographic analyses (92%) was sufficient to conclude that apo-VLDL-B and apo-VLDL-II are the major and possibly the only apoproteins of chicken VLDL. The molar ratio of the apo-VLDL-II monomer to apo-VLDL-B was estimated to be 32.

Animals↗
PubMed1979

Glucan induced modification of experimental Staphylococcus aureus infection in normal, leukemic and immunosuppressed mice.

Glucan, a beta 1 leads to 3 polyglucosidic component of Saccharomyces cerevisiae, was evaluated for its ability to provide nonspecific resistance to S. aureus septicemia in AKR/J mice. Intravenous injection of glucan (0.45 mg/mouse) 7 and 4 days prior to intravenous challenge with S. aureus (1.0 x 10(9)) resulted in a significantly increased survival as compared to control mice. Histological examination of the kidneys revealed that glucan decreased tissue necrosis associated with systemic staphylococcal disease. A post-treatment regimen of glucan significantly enhanced survival of AKR/J mice with lymphocytic leukemia as well as leukemic mice with experimentally induced systemic staphylococcal infection. The effect of glucan on S. aureus septicemia was also evaluated in cyclophosphamide-treated mice. Glucan increased peripheral leukocyte counts as well as significantly enhanced survival of cyclophosphamide-treated mice with systemic S. aureus infection. Histopathological examination revealed that glucan administration markedly inhibited renal and hepatic pathology in cyclophosphamide-treated mice following intravenous challenge with S. aureus. These data denote that glucan provides nonspecific resistance to bacterial sepsis in normal, leukemic as well as immunosuppressed mice.

Animals↗
PubMed1979

R-wave synchronized blood-pool imaging.

Three methods for determining the left ventricular ejection fraction (EF) from R-wave synchronized blood-pool images were compared to contrast angiography; the reproducibility of these methods was established in 51 patients. The EF was systematically underestimated by the fixed region-of-interest (ROI) method compared to the two methods that used varying ROI's which track the left ventricular boundary. All methods correlated reasonably well with angiography and were highly reproducible. Use of varying ROI's resulted in EF values that were essentially identical to those determined by angiography. Resolution-recovery image processing appeared to improve reproducibility when varying ROI's were used.

Angiography↗
PubMed1978

Increased resistance to Staphylococcus aureus infection and enhancement in serum lysozyme activity by glucan.

Glucan is a potent reticuloendothelial stimulant whose immunobiological activity is mediated, in part, by an increase in the number and function of macrophages. In studying the role of glucan as a mediator of antibacterial activity, we attempted to ascertain the ability of glucan to modify the mortality of mice with experimentally induced Gram-positive bacteremia, and to enhance antibacterial defenses in rats as denoted by serum lysozyme and phagocytic activity. After intravenous administration of glucan, serum lysozyme concentrations were increased approximately sevenfold over control concentrations. The increase in serum lysozyme appeared to parallel the glucan-induced increase in phagocytosis and induced hyperplasia of macrophages. Prior treatment of mice with glucan significantly enhanced their survival when they were challenged systemically with Staphylococcus aureus. These studies indicate that glucan confers an enhanced state of host defense against bacterial infections.

Animals↗
PubMed1978

Myocardial imaging with 201thallium: an analysis of clinical usefulness based on Bayes' theorem.

Rest-exercise thallium-201 (201Tl) myocardial imaging and rest-exercise electrocardiography were performed in 137 patients with suspected coronary artery disease (CAD). The final diagnosis of coronary disease was made by arteriography. Sensitivity and specificity for the ECG and thallium studies alone or combined were then determined. Based on these data, the posttest probability of CAD with a normal or abnormal test was calculated using Bayes' theorem for disease prevalences ranging from 1%--99%. The difference between the probability of disease with a normal test and the probability of disease with an abnormal test was also calculated for each prevalence range. The results demonstrate that 201Tl imaging discriminates between disease absence or presence better than does the ECG. However, both the ECG and thallium studies provide rather poor discrimination between disease and no disease when the disease prevalence is low (less than 0.20) or high (greater than 0.70). Because of this characteristic, it is unlikely that screening tests for CAD will prove useful unless the disease prevalence in the group under study is in the moderate (0.20--0.70) range.

Angiography↗