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Biomedical subjects

C Garcia

Publications and source records attributed to C Garcia.

At least 289 records · Page 16Linked to original sources
PubMed1979

Effects of polybrominated biphenyl on a discrimination task in rats.

Learning or performance of an operant discrimination task by laboratory rats in Skinner boxes was studied as a function of subchronic treatment with polybrominated biphenyl (PBB) (1.0 mg/kg, 3.0 mg/kg or 6.0 mg/kg for 20 days). Acquisition of the discrimination task was similar for experimental and control rats at each dose level. Response times were slower for the 1.0 mg/kg rats but were like controls for the 3.0 and 6.0 mg/kg animals. Extra responses occurring in the absence of auditory discriminative stimuli increased significantly for the 1.0 mg/kg rats (hyperactivity), were no different from controls for the 3.0 mg/kg rats and decreased significantly for the 6.0 mg/kg animals (CNS depression). The weights of PBB animals did not differ significantly from controls. Analyses of brains and plasma by electron capture gas chromatography yielded detectable levels of PBB as long as 10 months following the last PBB administration. PBB in brains and plasma varied directly as a function of dose administered.

Animals↗
PubMed1978

A case of primary amebic meningoencephalitis. Light and electron microscopy, and immunohistologic studies.

A 56-year-old alcoholic developed primary meningoencephalitis and died 3 weeks later. Autopsy revealed multiple areas of necrosis and acute and granulomatous inflammation in the brain and pancreas. Trophozoites and cysts were discovered in the brain and trophozoites alone in the pancreas. Morphologic studies revealed some parasitic features described as characteristic for Naegleria, but clinical, histological and immunohistological features favored in Acanthamoeba infection. This study calls for caution in the use of pure morphological criteria for the differential diagnosis of Naegleria and Acanthamoeba in humans. Cultural characteristics, immunohistology and serologic tests are probably more reliable for differentiating these parasites.

Amebiasis↗
PubMed1976

[Possibilities and limitations in the conservation of traumatized deciduous teeth].

A survey is given on the various traumatic lesions of deciduous teeth and the therapeutical measures. The latter aim at retaining every traumatized tooth, if possible, in order not to disturb the growth of the jaws. A study by the authors on 116 recently traumatized deciduous teeth showed that almost half of the teeth could be retained.

Child↗
PubMedDate not supplied

L-amino acid load to enhance PET differentiation between tumor and inflammation: an in vitro study on (18)F-FET uptake.

Labeled amino acids (AA) are tumor tracers for use in nuclear medecine. O-(2-[(18)F]fluoroethyl)-L-tyrosine (FET) is transported by the L-system, known to function as an exchanger. In vitro utilization of FET, after a preload or prior to an afterload of non radioactive L-amino acids, was evaluated in order to measure the potential effects of AA content on the distinction between tumor and inflammatory lesions. Cellular uptake of FET was studied on rat osteosarcoma cells (ROS 17/2.8) and human leukocytes, initially loaded with nonradioactive L-tyrosine or L-methionine. FET efflux was evaluated from cells loaded with nonradioactive L-phenylalanine after tracer uptake. ROS 17/2.8 showed a higher sensitivity to preload and afterload effects on cellular FET content as compared with the leukocytes. We conclude that preload with L-tyrosine, prior to the administration of FET, may be a potential procedure to improve PET differentiation between tumor and inflammatory lesions.

Amino Acids↗
PubMedDate not supplied

Cocaine blunts human CD4+ cell activation.

Cocaine is reported to be immunotoxic. The biochemical mechanisms responsible for the immunopharmacological outcomes of cocaine in vivo and in vitro remain, however, to be fully elucidated. Our experimental data confirm that exposure of normal human T cells to micromolar concentrations of cocaine modulates T-cell responses to stimulation by a variety of stimuli, and indicate that cocaine impairs early activation events during CD4+ but not CD4- T-cell stimulation. Pre-incubation of enriched CD4+ T-cell subpopulations that express the homing receptor CD62L with nanomolar concentrations of the endogenous opioid peptide beta-endorphin leads to a more severe impairment of activation than that noted following pre-incubation with micromolar concentrations of cocaine alone. These findings begin to elucidate the molecular and cellular mechanisms of the immunopathology of cocaine. Our data support the proposition that cocaine abuse may place cocaine-abuser HIV-seropositive individuals at increased risk of opportunistic infections.

Antigens, CD↗
PubMedDate not supplied

Importance of the phenotypic state of vascular smooth muscle cells on the binding and the mitogenic activity of endothelin.

Smooth muscle cells of the rabbit aorta, when grown in vitro, express distinguishable forms of phenotypes (contractile and synthetic). On contractile cells, ET-1 specifically bound to a single class of high affinity (KD = 128 pM) and high capacity (Bmax = 66,000 sites/cell) binding sites. But, whereas affinity of [125I]-ET-1 was not significantly affected by phenotypic modulation, synthetic cells displayed a 10-fold lower [125I]-ET-1 binding capacity than contractile smooth muscle cells. Similarly, the mitogenic effect of ET-1 on smooth muscle cells was considerably lower for synthetic than for contractile cells. The ET-1 receptor on primary cells was recognized by sarafotoxin S6b and the different ET-related peptides with an order of potency [ET-1 greater than S6b greater than ET-3 greater than Big ET-1 much greater than ET(16-21)] identical to that inducing smooth muscle cell growth. Therefore, these data indicate that the binding and the mitogenic effects of ET-1 on smooth muscle cells might be of different magnitudes depending on the phenotypic state of these cells.

Animals↗