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Biomedical subjects

C Roy

Publications and source records attributed to C Roy.

At least 217 records · Page 12Linked to original sources
PubMed1986

Incidence of strains producing plasmid determined beta-lactamases among carbenicillin resistant Pseudomonas aeruginosa.

A total of 1056 strains of Pseudomonas aeruginosa isolated from human clinical specimens from patients was collected from eight laboratories in order to study the frequency of plasmid-determined beta-lactamase producers and the different enzymes represented. The strains from each laboratory comprised consecutive, non-repeated, clinical isolates. In the 166 strains selected because they were carbenicillin resistant, the isoelectric points of the beta-lactamases were studied by means of analytical isoelectric focusing and the different types of plasmid-determined beta-lactamases identified. Seventy-five of the strains (45.18%) were plasmid-mediated beta-lactamase producers; the frequency varied among laboratories from 0% to 100%. Overall the most frequently identified beta-lactamase type was PSE-1 (49.34%) followed by TEM-1 (37.34%). The remaining carbenicillin-resistant strains did not produce plasmid-determined beta-lactamases.

Carbenicillin↗
PubMed1986

The primary structure of the ribosomal A-protein (L12) from the moderate halophile NRCC 41227.

The complete amino acid sequence of the ribosomal A-protein (equivalent to L7/L12 in Escherichia coli) from a moderate halophile, NRCC 41227, has been determined using an automatic Beckman sequencer and by the manual Edman cleavage of peptides obtained from selective proteolytic cleavage of the ribosomal A-protein. The protein contains 122 amino acids and has a composition of Asp5, Asn2, Thr6, Ser6, Glu21, Gln2, Pro2, Gly12, Ala21, Val14, Met4, Ile4, Leu9, Phe2, Lys11, and Arg1, and a molecular weight of 12 537. It has a net negative charge of -14 and is, therefore, slightly more acidic than other eubacterial ribosomal A-proteins. The phylogenetic tree, obtained by computer analysis of the amino acid sequence of this and other eubacterial A-proteins, indicate these proteins form five subgroups within the eubacterial kingdom. The moderate halophile NRCC 41227 is part of a group of Gram-negative bacteria that include E. coli and another moderate halophile Vibrio costicola. The sequence data provides further evidence that the moderate and extreme halophiles have evolved by separate pathways.

Amino Acid Sequence↗
PubMed1986

Stimulator T-cells and the regulation of growth factors produced in the murine mixed leukocyte reaction.

Previous work had implicated T cells within the stimulating population as having a significant role in the MLR. We now report that depletion of T cells from the stimulators caused a reduction in proliferative response in mixed leukocyte reaction (MLR) by 50% or more. This response could be restored by adding T-enriched cells from the stimulators but not from the responders. During MLR, the T-cells in the stimulating population demonstrated changes characteristic of early activation, namely, increase in RNA synthesis. Stimulator T-cells have been shown to regulate the interleukin 2 (IL 2) production in mixed leukocyte culture (MLC). Depletion of T cells from the stimulators reduced the level of IL 2 in the culture. Addition of IL 2 to the cultures containing T-depleted stimulators reconstituted the proliferative response. Our data suggest that there may be alternative ways of producing IL 2-like growth factors. Depletion of T cells from the stimulators allows the detection of a growth factor which differs from IL 2 in its mode of production. We conclude that optimal proliferation in the MLR requires that the stimulating population contain T cells which regulate the growth factors in the culture.

Animals↗
PubMed1986

[Multifocal tuberculosis in a 15-year-old child].

We report the case of a 15 year-old boy, presenting with juxta-articular swellings and lacunar skeletal lesions associated with prolonged fever and cachexia. Among the multiple bacteriological samplings, only the trans-osseous puncture of a tibial lacunar lesions, yielded Bacillus tuberculosis. With triple anti-tuberculous chemotherapy, fever and juxta-articular swellings disappeared. However, several articular ankyloses persist, which might need a surgical correction.

Adolescent↗
PubMed1985

[Hurst-type acute leukoencephalitis with complete recovery in a child].

A case of acute haemorrhagic leukoencephalitis in an 11-year old girl demonstrates the usefulness of computerized tomography which shows large, asymmetric hypodense areas in the white matter and diffuse oedema. The causative role of a Mycoplasma pneumoniae infection is suggested by positive serology and by a high level of cold anti-l agglutinins. Treatment with corticosteroids in massive doses combined with a tetracycline resulted in complete cure without sequelae.

Acute Disease↗
PubMed1985

Stimulation of the murine mixed leukocyte reaction: optimal proliferation of responders requires activation of stimulators.

In characterizing the functional properties of the stimulators in a mixed leukocyte reaction (MLR) we have established that the optimally effective stimulators must themselves be capable of undergoing the early stages of proliferative activation. We treated the stimulators with sublytic doses of a variety of agents (ouabain, ultra-violet radiation, 5-fluorouracil and colchicine), which have been reported to inhibit their stimulating capacity, and then in parallel experiments, we examined the treated cells for their capacity to stimulate allogeneic cells and their ability to respond to Con A. A direct correlation was found between the capacity of mitomycin C-treated splenocytes to stimulate allogeneic cells in an MLR and their ability to undergo changes characteristic of pre-S phase activation, namely, increases in K+ influx and in cell size, in response to Con A. This correlation also existed in the case of metabolically active but immunosuppressed splenocytes from mice undergoing late graft-versus-host (GVH) reaction: these cells did not show increase in potassium influx in response to Con A and their stimulating ability was inhibited. Using fluorescein labelled anti-Thy 1.2 as a marker for T cells in the stimulating population, it was shown that a considerable fraction (up to one third) of the blasts in a mixed leukocyte culture (MLC) originated in the mitomycin C-treated stimulating population. These data are consistent with the hypothesis that induction of maximal proliferation, in MLR, requires that certain of the cells (mainly T cells) of the stimulating population undergo the early stages of activation.

Animals↗
PubMed1985

Regulation of hormonal responsiveness in LLC-PK1L cells grown in defined medium.

LLC-PK1L cells, a kidney-derived cell line, were able to grow in a chemically defined medium. Growth of the cells in the presence of retinol, ergocalciferol, d-alpha-tocopherol, 3,3',5-triiodothyronine, hydrocortisone, l-carnitine, d-l-methionine-S-methylsulfonium chloride, insulin, transferrin, cholesterol, and sodium linoleate increased the number of vasopressin receptors by 20- to 40-fold. All the newly detectable vasopressin receptors were coupled to the adenylate cyclase activity with similar efficiency. The same growth conditions did not alter the basal adenylate cyclase activity or the responses to calcitonin, parathyroid hormone, prostaglandin, adenosine, and GTP. In contrast, the increased responsiveness of the adenylate cyclase to vasopressin was associated with a reduced response to isoproterenol. Such an inverse correlation was also found when the time course of vasopressin receptor induction was studied. The supplemented medium permitted the growth of cells for several weeks. The effects of the enriched medium were fully reversible when we returned to the original cell growth medium. Thus such a cellular system appears as a useful tool for further work in cellular and kidney endocrinology and for detailing the molecular mechanisms of receptor-adenylate cyclase regulations.

Adenylyl Cyclases↗
PubMed1985

Complementary role of wrist arthrography in non-union of scaphoid fractures.

Plain radiographs and wrist arthrography of 11 patients with non-united fractures of the scaphoid were retrospectively studied. The arthrographic feature of non-union was found to be opacification of the fracture line and, secondly, of the midcarpal compartment, whereas in patients with fibrous or cartilaginous union no opacification of the fracture line was obtained. There was no single plain radiographic feature that could distinguish non-union from fibrous or cartilaginous union.

Adolescent↗