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Biomedical subjects

C L Hall

Publications and source records attributed to C L Hall.

At least 73 records · Page 4Linked to original sources
PubMed1981

Binding of Salmonella typhimurium lipopolysaccharides to rat high-density lipoproteins.

These studies were undertaken to investigate the binding of gram-negative bacterial lipopolysaccharides (LPS) to high-density lipoproteins (HDL) of rat plasma. Purified Salmonella typhimurium LPS, intrinsically labeled with [3H]-galactose, bound rapidly in vitro to isolated rat HDL. Maximal binding of LPS to HDL occurred when LPS and HDL were incubated with lipoprotein-free plasma (rho greater than 1.21 g/ml). Since LPS, when purified, form large aggregates, we tested the hypothesis that disaggregation of LPS enhances LPS-HDL binding. We found that calcium chloride (1 mM), an agent which prevents LPS disaggregation, inhibited binding of LPS to HDL by interfering with the modification of LPS by lipoprotein-free plasma. Conversely, sodium deoxycholate (0.15 g/dl), which disaggregates LPS, greatly increased binding of LPS to HDL in the absence of lipoprotein-free plasma. Analysis of labeled LPS by sodium deodecyl sulfate-polyacrylamide gel electrophoresis showed only minor differences in the sizes of LPS molecules before and after binding to HDL, suggesting that chemical modification of LPS is not required for binding. The results provide evidence that disaggregation increases the binding of LPS to HDL.

Animals↗
PubMed1981

Interactions during inhibition of growth of Aspergillus parasiticus by gentian violet.

The interrelationships of gentian violet and the growth of Aspergillus parasiticus NRRL 2999 were investigated with static cultures in a yeast extract-sucrose liquid medium. The dye was fungistatic but not fungicidal at concentrations up to 32 microgram/ml. Growth inhibition was dependent on the concentration of the added dye and on the age of the culture. At 8 microgram/ml with a spore inoculum, growth was inhibited for 6 days while 32 microgram/ml added to a 4-day-old culture inhibited for only 24 hr. Initiation of a normal rate of growth coincided with disappearance of the dye from the medium. The disappearance followed first order kinetics. The dye appeared to bind to the mycelium prior to its apparent disappearance from the medium. Gentian violet appeared to inhibit spore germination by inhibiting a critical point in the spore swelling phenomenon. In addition, growth subsequent to germination was retarded.

Animals↗
PubMed1980

Single-dose amoxicillin therapy for urinary tract infection. Multicenter trial using antibody-coated bacteria localization technique.

Urine specimens from 134 women with acute, uncomplicated urinary tract infection at three medical centers were examined by the antibody-coated bacteria (ACB) assay. Patients with negative assays (suggesting bladder infection alone) were randomized to receive either a single 3-g oral dose of amoxicillin trihydrate or conventional ten-day courses of sulfa-methoxazole-trimethoprim or oral ampicillin sodium. Comparable results were obtained with the three regimens for ACG-negative infection: 90% eradication of the original organism with single-dose amoxicillin, 100% with sulfamethoxazole-trimethoprim, and 96% with ampicillin. The overall incidence of ACB positivity was 32.1%, ranging from 8% to 63% at the three institutions. This difference seemed to be related to the ease of access to medical care: women with easy access having low rates of ACB positivity and those with poor access having high rates.

Acute Disease↗
PubMed1980

Studies on electron transfer from general acyl-CoA dehydrogenase to electron transfer flavoprotein.

General acyl coenzyme A dehydrogenase from pig liver mitochondria, which was prepared as a complex with C8CoA and mixed with electron-transfer flavoprotein, rapidly reduces the electron-transfer flavoprotein to a 1-electron-reduced form (anionic semiquinone). A second electron is transferred more slowly to form the fully reduced electron-transfer flavoprotein. Transfer of the first electron is faster than turnover in the dichlorophenolindophenol reduction assay. These observations show that the acyl-CoA dehydrogenase-electron-transfer flavoprotein system utilizes this semiquinone catalytically. A concomitant appearance of semiquinone from the general acyl-CoA dehydrogenase could not be detected under similar conditions.

Acyl-CoA Dehydrogenases↗
PubMed1980

Size heterogeneity of Salmonella typhimurium lipopolysaccharides in outer membranes and culture supernatant membrane fragments.

Enterobacteriaceae cells growing in liquid media shed fragments of their outer membranes. These fragments, which may constitute a biologically important form of gram-negative bacterial endotoxin, have been reported to contain proteins, phospholipids, and lipopolysaccharides (LPS). In this study we compared the sizes of LPS molecules in shed membrane fragments and outer membranes from cells growing in broth cultures. Using conditional mutants of Salmonella typhimurium which incorporate specific sugars into LPS, we analyzed radiolabeled LPS by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This technique revealed that S. typhimurium LPS are more heterogeneous than previously known; molecules possessing from 0 to more than 30 O-chain repeat units were identified in outer membranes, supernatant fragments, and purified LPS. The size distributions of LPS molecules in outer membranes and supernatant fragments were similar; supernatant fragments appeared to be slightly enriched in molecules with long O-polysaccharide chains. Our results indicate the LPS molecules of many sizes are synthesized, translocated to outer membranes, and released into culture supernatants. Since the hydrophilic O-polysaccharides extend from bacterial surfaces into the aqueous environment, our findings suggest that the cell surface topography of this bacterium may be very irregular. We also speculate that heterogeneity in the degree of polymerization of O-antigenic side chains may influence the interactions of the toxic moiety of LPS (lipid A) with host constituents.

Cell Membrane↗
PubMed1979

Radioimmunoassay for Gram-negative bacterial lipopolysaccharide O antigens: influence of antigen solubility.

We have developed a solid-phase radioimmunoassay technique for specific gram-negative bacterial lipopolysaccharide (LPS) O antigens. The method exploits the high-titer, specific immunoglobulin M response of the rabbit to LPS immunization to measure as little as 5 ng of homologous LPS per ml with less than 0.5% cross-reactivity toward heterologous LPS or culture supernatants. We found that O antigen in complete LPS was less available for antibody binding than O antigen in the soluble polysaccharide derived by mild acid hydrolysis of LPS and that triethylamine-induced disaggregation of complete LPS increased its activity in the assay. Quantitation of O antigen with the assay was thus influenced by the physical state of LPS or "free" O antigen.

Escherichia coli↗
PubMed1979

Origin of urinary fibrin-fibrinogen degradation products in renal glomerular disease.

The origin and mechanism of renal clearance of urinary 'fibrin-fibrinogen degradation products' (FDP) were studied in patients with renal glomerular diseases associated with heavy, non-selective proteinuria and high levels of urinary FDP. The results indicated that the urinary FDP arose primarily by the filtration of unaltered plasma fibrinogen through a damaged and abnormally permeable glomerular basement membrane and that a variable degree of lysis of the filtered fibrinogen occurred in the urine. The lysis of cross-linked fibrin in intraglomerular deposits, as evidenced by the presence of dimeric fragment D in the urine, appeared to contribute only a small amount to the total urinary FDP excretion.

Electrophoresis, Polyacrylamide Gel↗
PubMed1978

Circulating immune complexes in Hodgkin's disease.

Levels of circulating immune complexes (CIC) in the serum of patients with Hodgkin's disease were measured by the Raji cell radioimmunoassay. Elevated levels of immune complexes (mean value of 49 microgram/ml +/- 21 SE) were detected in 20 of 40 (50 per cent) untreated patients. After treatment, the level of CIC was normal (less than 15 microgram/ml) in 39 of 41 patients. Recurrent disease developed in two of the 39 patients with normal post-treatment levels of CIC and in one of the two patients with elevated post-treatment levels during the follow-up period of six months to six years. Elevated levels of CIC were detected in patients with Hodgkin's disease in stages I, II and III but not in stage IV. No significant correlations were found in the frequency of elevated levels of CIC or the values observed, and the presence or absence of symptoms (fever, sweats, weight loss) or the histologic subtype of the tumor. Our data indicate that the measurement of CIC by the sensitive and specific raji cell assay may prove useful in the management of patients with Hodgkin's disease. In particular, serial measurement of the level of CIC could be employed to monitor the response to treatment and to detect recurrent diseases.

Antigen-Antibody Complex↗
PubMed1978

Immune complex mediated diseases.

Immune complexes formed in the circulation are believed to be the principal pathogenetic agents in certain human diseases, notably in various forms of glomerulonephritis and arteritis. Criteria for the recognition of immune complex deposits in tissue are discussed and recently developed sensitive methods that detect circulating immune complexes are reviewed. In addition, the evidence implicating certain antigens and causative agents in human immune complex mediated glomerulonephritis and arteritis is evaluated.

Animals↗