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Biomedical subjects

G Castellanos

Publications and source records attributed to G Castellanos.

17 recordsLinked to original sources
PubMed1988

Long esophagoplasty: functional study.

The functional results of different types of plasty were evaluated in 46 patients who had undergone esophageal replacement for different pathologies. The patients were classified into three groups according to the type of plasty: I) 19 ileocecocolonoplasties (ICC), II) 11 left colonoplasties (LC), III) 16 gastroplasties (GP). The postoperative studies made were: a) clinical evaluation, b) radiological barium contrast study, c) isotopic transit of semisolid food marked with 99m-Tc colloidal sulfur and d) manometry. The clinical evaluation disclosed no significant differences between the three groups. Isotopic scans revealed more rapid emptying of the ICC, with elimination by the ileal segment in the first minute of 76.3 +/- 3.3% of the isotope, and by the entire plasty of 79.4 +/- 4.2% in 15 minutes (p less than 0.001). The manometric study showed non-response by the GP. The motor activity of the terminal ileoplasty was greater than that of the other plasties studied, and that of the right colonoplasty was greater than that of the left (p less than 0.01). Likewise, the clearance of acid (HCl 0.1N) by the ICC was more rapid than that of the LC (p less than 0.01). It is concluded that, functionally, the ICC is a better long esophagoplasty than the other procedures studied.

Adult↗
PubMed1983

A comparison of liquid-holding recovery and photoreactivation in halophilic and non-halophilic bacteria.

The ability of the extreme halophile Halobacterium cutirubrum to recover from the effects of ultraviolet radiation during liquid holding in the dark in non-nutrient medium has been compared with that of (i) a moderately halophilic bacterium (NRC 41227) and (ii) Escherichia coli B. The photoreactivabilities of all three bacteria have also been studied. The extreme halophile was incapable of liquid-holding recovery in these conditions, in marked contrast to both E. coli B and the moderate halophile, and also failed to recover when held in nutrient medium in the dark. These results strongly support the hypothesis that H. cutirubrum lacks DNA excision repair. It was also found that ultraviolet-irradiated H. cutirubrum could be almost completely photoreactivated from any level of survival in the range 10(-4)-80%, provided exposure to visible light was not delayed, whereas the moderate halophile resembled E. coli B and had a comparatively limited capacity for photoreactivation.

Cell Survival↗
PubMed1982

The effect of ultraviolet radiation on early stages of activation of human lymphocytes: inhibition is independent of effects on DNA.

Low doses (30-84 ergs/mm2, 1 erg = 10(7) J) of ultraviolet radiation (UV) caused severe inhibition of the proliferation of human lymphocytes in vitro. Greatest inhibition was produced when resting cells were irradiated immediately prior to stimulation with concanavalin A (Con A); this was true whether activation was measured by the incorporation of labelled leucine, uridine, or thymidine. If UV was applied at 44 h after culture in presence of Con A, the incorporation of [3H]thymidine measured 4 h later was seen to be inhibited but transcription and translation were scarcely affected. UV, applied after the appearance of the Con A induced thymidine transport system, did not inhibit its function. The disaggregation of chromatin and increase in nuclear volume characteristic of, and essential to, the proliferative response of lymphocytes were completely inhibited if the cells were irradiated before mitogen was added to the cultures, but were unaffected if irradiation occurred after 16 h of culture in presence of Con A. Cells irradiated with 84 ergs/mm2 at the onset of culture with mitogen did not show the early increase of cation pump function which is a characteristic of stimulated lymphocytes, when this was measured by means of 86Rb uptake after 2-4 h culture. The mitogen-stimulated activation of cation pump function has previously been shown to be unaffected by concentrations of cycloheximide and actinomycin D which produce virtually complete inhibition of protein and RNA synthesis, respectively. The major inhibitory effect of UV treatment of lymphocytes at onset of culture with Con A is therefore not on DNA or on DNA synthesis, but on some component(s) of the early activation process, possibly at the cell periphery; inactivation of this component prevents cells from proceeding into later stages of the proliferative pathway.

Biological Transport↗
PubMed1978

[Uptake of tryptophan and tyrosine in some cases of manic depressive psychosis and schizophrenia (author's transl)].

The uptake of tryptophan and tyrosine by the brain has been studied in 6 manic-depressive patients and in 8 schizophrenics. In an attempt to saturate the blood-brain transport mechanisms, this uptake has been evaluated by measuring the arteriovenous differences (arterial plasma-internal jugular plasma) of these two amino acids before and after perfusion with L-dopa and L-5-HTP. Considering a positive difference as an uptake and a negative one as an outflow, results show (1) in melancholia an uptake of tryptophan and an outflow of tyrosine; (2) in mania an uptake of tyrosine and an outflow of tryptophan, and (3) in schizophrenia an outflow of tryptophan accompanied with either an uptake or an outflow of tyrosine. In addition, the kinetics of tryptophan binding to plasma proteins and the ratio of tryptophan/tyrosine uptake are different in manic-depressive illness and in schizophrenia. These results support the view that a disturbance in the blood-brain transport mechanisms of tryptophan and tyrosine could be involved in the physiopathology of manic-depressive illness and schizophrenia.

Bipolar Disorder↗