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Biomedical subjects

E Weiss

Publications and source records attributed to E Weiss.

At least 181 records · Page 10Linked to original sources
PubMed1986

Substrate utilization by Campylobacter jejuni and Campylobacter coli.

An attempt was made to elucidate in Campylobacter spp. some of the physiologic characteristics that are reflected in the kinetics of CO2 formation from four 14C-labeled substrates. Campylobacter jejuni and C. coli were grown in a biphasic medium, and highly motile spiral cells were harvested at 12 h. Of the media evaluated for use in the metabolic tests, minimal essential medium without glutamine, diluted with an equal volume of potassium sodium phosphate buffer (pH 7.2), provided the greatest stability and least competition with the substrates to be tested. The cells were incubated with 0.02 M glutamate, glutamine, alpha-ketoglutarate, or formate, or with concentrations of these substrates ranging from 0.0032 to 0.125 M. All four substrates were metabolized very rapidly by both species. A feature of many of these reactions, particularly obvious with alpha-ketoglutarate, was an immediate burst of CO2 production followed by CO2 evolution at a more moderate rate. These diphasic kinetics of substrate utilization were not seen in comparable experiments with Escherichia coli grown and tested under identical conditions. With C. jejuni, CO2 production from formate proceeded rapidly for the entire period of incubation. The rate of metabolism of glutamate, glutamine, and alpha-ketoglutarate by both species was greatly enhanced by increased substrate concentration. The approach to the study of the metabolism of campylobacters here described may be useful in detecting subtle changes in the physiology of cells as they are maintained past their logarithmic growth phase.

Campylobacter↗
PubMed1986

Prevalence of antibodies to Legionella species in a series of patients in Israel.

A collection of serum specimens from 77 patients at various hospitals or clinics in Israel was used to determine the usefulness of the enzyme-linked immunosorbent assay (ELISA) with a multivalent antigen for the detection of legionella antibodies. Rickettsial infection rather than legionellosis was suspected in most of these patients. The multivalent antigen was derived from Legionella pneumophila serogroups 1-6, L. bozemanii WIGA, and L. micdadei TATLOCK. A preliminary test of the multivalent antigen with specific rabbit antisera had shown that homologous reactions were not appreciably reduced in strength or specificity by the presence of the heterologous antigens. The results with the human sera revealed that 28 patients (36%) had reciprocal dilution titers greater than or equal to 1,280 and 43 (56%) had titers greater than or equal to 320. Tests with univalent antigens identified L. bozemanii as the only or principal antigen reacting with 13 of these sera. In contrast to the sera reacting with other legionella antigens, the great majority (11 of 13) of L. bozemanii-positive sera reacted also with Rickettsia typhi. The data suggest that most, but not all, reactions with L. bozemanii were elicited by a cross-reacting R. typhi antigen. These results were confirmed by cross-absorption tests.

Animals↗
PubMed1986

An improved method for adrenalectomy of suckling rats. The influence of thrombin treatment and deoxycorticosterone substitution on survival and on hepatic and renal enzyme activities.

Adrenalectomy of suckling rats is complicated by a high mortality rate, caused by the loss of blood (early mortality) and by the disturbed sodium-potassium balance (late mortality). Treatment of the abdominal cavity with a thrombin solution and a daily administration of deoxycorticosterone glucoside (DOC) decrease the total mortality remarkably. DOC treatment has no influence on renal beta-glucosidase and beta-galactosidase as well as on hepatic tyrosine aminotransferase activity, whereas hepatic serine dehydratase activity exhibits a time- and dosage-dependent response to this hormone. The DOC effect is very likely a consequence of the glucocorticoid-like action of the synthetic hormone, which competes with the endogenous glucocorticoids for the hepatic receptor molecules.

Adrenal Glands↗
PubMed1986

Bacterial adherence to intravenous catheters and needles and its influence by cannula type and bacterial surface hydrophobicity.

Bacterial adherence to intravenous (IV) catheters and needles (cannulas) was studied morphologically by scanning electron microscopy and determined quantitatively with radiolabeled bacteria. Electron micrographs showed that bacteria adhered well to IV cannulas with formation of microcolonies. The adherence process was studied quantitatively, as related to cannula composition and bacterial surface hydrophobicity. The adherence of the bacteria examined (per square centimeter) was lowest to siliconized steel needles, higher to Teflon catheters, and highest to polyethylene catheters. The results for Staphylococcus aureus were (9.9 +/- 0.9) X 10(5) bacteria/cm2 adhered to steel needles, (37.2 +/- 2.8) X 10(5) bacteria/cm2 to Teflon catheters, and (168.4 +/- 15.6) X 10(5) bacteria/cm2 to polyethylene catheters. Hydrophobic bacteria (S. aureus and Serratia marcescens), as determined by their adherence to liquid hydrocarbons, adhered better than less hydrophobic species (Escherichia coli). The role of hydrophobicity was documented by showing that hydrophobic S. marcescens adhered to IV catheters 18- to 27-fold better than its less hydrophobic mutants. It is concluded that IV steel needles have an advantage over plastic cannulas regarding bacterial adherence in vitro, and inasmuch as infectious complications in vivo were indeed shown to be lower with IV needles, their usage should be preferred.

Adhesiveness↗
PubMed1985

A common origin of rickettsiae and certain plant pathogens.

On the basis of ribosomal RNA sequence comparisons, the rickettsia Rochalimaea quintana has been found to be a member of subgroup 2 of the alpha subdivision of the so-called purple bacteria, which is one of about ten major eubacterial divisions. Within subgroup alpha-2, R. quintana is specifically related to the agrobacteria and rhizobacteria, organisms that also have close associations with eukaryotic cells. This genealogical grouping of the rickettsiae with certain plant pathogens and intracellular symbionts suggests a possible evolution of the rickettsiae from plant-associated bacteria.

Bacillus subtilis↗
PubMed1985

T-antigen is the only detectable protein on the nucleosome-free origin region of isolated simian virus 40 minichromosomes.

A nucleosome-free region or nucleosome gap, containing the origin of replication and the transcriptional promoter elements, is observed on 20%-25% of the SV40 minichromosomes isolated at physiological ionic strength at late time during the infectious cycle. We found that this subpopulation of gapped minichromosomes was more sensitive to digestion with a variety of single-cut restriction enzymes than the rest of the minichromosomes. This increased digestibility of gapped minichromosomes allowed us to excise the gap region by concomitant digestion with Bgl I and Msp I. T-antigen was the only detectable protein bound to this isolated chromatin fragment. In particular no histones could be detected. The presence of T-antigen on the gap region was confirmed by immunoelectron microscopy. Most of the T-antigen appeared to be located on the late side of the Bgl I restriction enzyme site.

Animals↗
PubMed1985

Identification of murine H-2Db histocompatibility antigens in cells transfected with cloned H-2 genes.

Clones of mouse L-cells transformed with 21 cosmids containing 15 major histocompatibility complex class I genes of C57BL10 (H-2b) sperm cell DNA were analyzed for the expression of their transfected H-2 and Qa/Tla genes. Three cosmids contained a single gene, mapping to the H-2D region. This gene encodes the H-2Db alloantigen: mouse L-cells transfected with cosmids containing this gene reacted with monoclonal antibodies and alloantisera specific for the H-2Db antigen and expressed a 46-kd H-2 heavy chain associated with beta 2-microglobulin in their cell membranes. Furthermore, these transfected cells were stimulators of, and targets for, anti-H-2Db cytotoxic T-lymphocytes. Eighteen cosmids contained 14 different genes mapping to the Qa and Tla regions. L-cells transfected with these genes did not express class I genes reacting with alloantisera or monoclonal antibodies against Qa2, Qa4 or TL differentiation antigens. In particular, the Qa2,3 gene of C57BL10 was not identified.

Animals↗
PubMed1984

Regulation of human B-cell colony growth.

PHA-induced B-cell enriched populations from venous blood of healthy adults developed into B-cell colonies. Analyses of individual colonies revealed that 80-85% of the cells in each colony were surface membrane immunoglobulin positive. Most colonies, 84%, contained surface IgM-bearing cells. Only a few, 16%, were found with surface IgG-bearing cells. Surface IgM- and surface IgG-bearing cells were not observed in the same colony. Thirty-nine percent of the colonies contained cells bearing surface IgD in addition to either surface IgM- or surface IgG-bearing cells. There was no evidence of cytoplasmic immunoglobulin in the colony cells. The development of B-cell colonies was T-cell dependent; it appears that at least two different T-cell subpopulations, one with low density (D = 1.05) and the other with high density (D = 1.08) are responsible for this helper effect. Monocytes were found to inhibit B-cell colony formation; the inhibition was mainly by endogenous prostaglandin E2 (PGE2) synthetized and released by monocytes. The addition of physiological concentrations of synthetic PGE2 to monocyte-depleted B-cell enriched populations inhibited B-cell colony growth, this paralleled the effect of endogenous PGE2 released by monocytes. Indomethacin (10-5 M) obviated the inhibitory effect of monocytes.

B-Lymphocytes↗
PubMed1984

Immunomorphologic characterization of chicken thrombocytes.

Chicken thrombocytes were enriched for immunization by utilizing their strong capacity to adhere to plastic surfaces. The produced rabbit anti-thrombocyte serum ATS 3 reacted by means of the unlabeled antibody enzyme method (PAP) specifically with thrombocytes of fixed chicken-blood smears, but not with lymphocytes or other blood cells. When ATS 3 (substrate diaminobencidinetetra-hydrochloride = DAB) and a 1.1 mixture of an anti-bursa serum and anti-thymus serum (ABS/ATS; substrate 4-chloro-1-naphthol = 4-Cl-1-N) were used simultaneously, thrombocytes revealed the brown color typical for DAB, whereas lymphocytes showed the blue stain of 4-Cl-1-N. The finding of a thrombocyte surface antigen not shared by lymphocytes is regarded as a further proof of the diversity of both cell systems, i.e., for the existence of a genuine thrombocyte system in chickens.

Animals↗
PubMed1984

Gonadotropin, prolactin and TSH secretion in patients with myasthenia gravis.

Hypothalamic pituitary function was studied in 13 patients with myasthenia gravis. Gonadotropin, TSH, and prolactin dynamics were investigated using conventional provocative stimuli. No consistent abnormality was found in either gonadotropin or prolactin release. Abnormal TSH responses to TRH administration was present in six of the 13 patients in association with normal free thyroxine indices and the absence of antithyroid antibodies. This latter observation is relevant when the association of myasthenia gravis with hyperthyroidism, thyroiditis and hypothyroidism is considered.

Adolescent↗
PubMed1984

Synergism between penicillin, clindamycin, or metronidazole and gentamicin against species of the Bacteroides melaninogenicus and Bacteroides fragilis groups.

Clinical isolates of the Bacteroides melaninogenicus and Bacteroides fragilis groups were tested for in vitro and in vivo susceptibility to penicillin, clindamycin, and metronidazole, used singly or in combination with gentamicin. The in vitro tests consisted of determinations of minimal inhibitory concentrations (MICs) carried out with or without constant amounts of gentamicin. When used alone, gentamicin had negligible effects on the bacteria but significantly reduced the MICs of penicillin, clindamycin, and metronidazole against 11, 10, and 3, of the 15 strains of the B. melaninogenicus group, respectively. The 15 strains of the B. fragilis group were all beta-lactamase producers and were highly resistant to penicillin or the combination of penicillin and gentamicin. However, gentamicin reduced the MICs of clindamycin and metronidazole against 1 and 7 strains of this group, respectively. The in vivo tests were carried out in mice and consisted of measurements of the effects of the antimicrobial agents on the sizes and bacterial content of abscesses induced by subcutaneous injection of bacterial suspensions. The results of the in vivo tests were generally consistent with those obtained in vitro with strains of the B. melaninogenicus group. Synergism between gentamicin and penicillin, clindamycin, or metronidazole was shown in 13, 10, and 3 strains of this group, respectively. In vivo synergism was not clearly demonstrated with the strains of the B. fragilis group, possibly because clindamycin and metronidazole used alone were highly efficacious. We suggest that the synergistic effect of gentamicin is due to its increased transport into the bacterial cell in the presence of penicillin and, possibly, other antimicrobial agents. The newly recognized in vitro and in vivo synergism between penicillin and other antimicrobial agents and an aminoglycoside in B. melaninogenicus may have clinical implications that deserve to be investigated.

Abscess↗
PubMed1984

Substrate utilization by Legionella cells after cryopreservation in phosphate buffer.

The objective of this study was to evaluate by relatively simple metabolic tests the usefulness of buffers and energy sources commonly used in Legionella growth media. Legionella pneumophila serogroups 1 to 6, Legionella micdadei, and Legionella bozemanii were grown in an enriched charcoal-yeast extract diphasic medium. The cells were washed thrice, suspended in various buffers (pH 6.9) with 1 or 5 mM MgSO4, and used immediately or after controlled-rate cryopreservation. CO2 produced and C incorporated into the cold trichloracetic acid-insoluble fractions from 14C-labeled substrates were determine. Potassium phosphate buffer (0.02 M) was as satisfactory as organic buffers for glutamate metabolism, but the addition of KCl or NaCl reduced activity. Metabolic activity for glutamate was not lost upon cryopreservation, and cryopreserved cells were used to test the utilization of other single or paired substrates. Rates of activity for serine, glutamate, threonine, and pyruvate, in this descending order, were high, and those for alpha-ketoglutarate, succinate, and gamma-aminobutyrate were low. Although glutamine was not used as rapidly as glutamate, when added to glutamate it was preferentially metabolized, possibly because of more rapid transport. When glutamate and serine were combined, glutamate furnished more C for CO2 and less for incorporation, whereas the reverse was true of serine. In conclusion, glutamate as an energy source may in some cases spare other amino acids for synthesis. alpha-Ketoglutarate, a common constituent of Legionella media, may reduce oxygen toxicity but is probably not a chief energy source.

Buffers↗
PubMed1984

Analysis of fatty acids of the genus Rochalimaea by electron capture gas chromatography: detection of nonanoic acid.

The fatty acid compositions of Rochalimaea quintana, strains Fuller and Guadalupe, and R. vinsonii, the Canadian vole agent, were determined in an effort to further characterize these bacteria. The cells were saponified with 5% NaOH in 50% methanol and acidified to pH 2. The methanolysates were extracted with chloroform, derivatized with 2,2,2-trichloroethanol, and analyzed using a Hewlett-Packard gas chromatograph equipped with a frequency pulse-modulated electron capture detector and a 3% OV-101 packed-glass column. The fatty acid profiles of the three Rochalimaea strains were similar, with octadecenoic acid (C18:1) the most abundant, followed by octadecanoic (C18:0) and hexadecanoic (C16:0) acids. Moderate to trace amounts of other acids were also present. Unexpectedly, well-defined peaks of nonanoic acid (C9) were found consistently. A portion of this acid, but not all, was extractable with chloroform. Since C9 is not reported as a usual component of bacteria and most analyses do not include a search for this fatty acid, this study was extended to three strains of Legionella and one of Campylobacter. Comparable results were obtained. Since these bacteria were grown in complex media which contain some C9, it is possible that the medium is the source of bacterial C9. Whether this compound can be synthesized by the bacteria remains to be investigated.

Chloroform↗
PubMed1984

Immunogold staining: adaptation of a cell-labeling system for analysis of human leukocyte subsets.

We have assessed the Immunogold Cell-Labeling System (IGS) for potential use in the clinical laboratory. In this technique, cell suspensions incubated with monoclonal mouse antibodies are reacted with anti-mouse antibodies labeled with colloidal gold. Surface marker cells, bearing dark blue-black granules, are easily distinguished by light microscopy. The percentages of T cells, T cell subsets, B cells, monocytes, or granulocytes identified by IGS corresponds with numbers obtained by flow cytometry analysis or immunofluorescence studies. Results by IGS and flow cytometry were similar for samples from patients with aberrant lymphocyte populations (e.g., leukemias) or from transplant recipients. IGS may thus be a useful diagnostic technique for studying neoplasias or other immunologically mediated disorders. This technique can also be used to characterize the surface phenotype of leukemic cell lines. The sensitivity and accuracy of IGS can be evaluated by measurements of different cell lines mixed in predetermined ratios.

Antibodies, Monoclonal↗