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Biomedical subjects

A Mateos

Publications and source records attributed to A Mateos.

48 records · Page 3Linked to original sources
PubMed1981

Dynamic analysis of cockroach giant interneuron activity evoked by forced displacement of cercal thread-hair sensilla.

This investigation involved extracellular recordings of cockroach abdominal giant interneuron (GI) action potentials evoked by cercal "threadlike" hair sensilla (THS) stimulation with a galvanometric device, by controlled displacements of about seven THS. Small and large GIs, distinguished by their amplitudes, were studied simultaneously. Only the small GIs were spontaneously active. Responses to sine, pulse, and ramp stimulation of sensilla produced phasic responses in both GI types. Some GIs were directionally sensitive and had shorter response latencies in the direction of best sensitivity while others were omnidirectional. Contralateral stimulation decreased responses to homolateral stimuli. In experiments using paired pulses (less than 50-ms intervals) there is a period of hyperexcitability, in large GIs, in which the response to the second stimulus is greater. Repeated stimulation caused an exponential decline in the response which was steeper in GIs at higher stimulating frequencies and had a faster time course in large GIs. Because of this last property GIs function as low-pass filters limiting the flow of information, with large GIs having a lower frequency "cutoff" than smaller GIs.

Abdomen↗
PubMed1980

[Immunocomplexes in pediatrics. I: Detection with polyethilenglycol precipitation (author's transl)].

Circulating seric immunocomplexes have a variable significance in every case and small amounts can be founded in nornal people. Sometimes immunocomplexes are a defensive mechanism against chronic antigenemia, but in other cases they produce important tissue injury, as in glomerulonephritis. There are many tests for detecting them, but no single test detects all types of complexes because of their heterogeneity. Authors explain the polyehthilene-glycol precipitation test which is compared it to other methods, as binding to C'1q, Fc or C'3b receptors or physical separation tests. Polyethilene-glycol precipitation was performed in several concentrations of albumin-antialbumin complexes. When eight sera were heated to 60 degrees C during 30 minutes the levels of precipitate decreased and they suggest it is due to antigen and antibody dissociation. Inversely, IgG progressive concentrations increased by formation of heat aggregated immunoglobulins. The 10 times repeated freezing and thawing of sera increased the optical density of precipitates from 0.047 to 0.057 and the raising was higher in pathological than in normal sera. Although the repeated thawing must be avoid its' role does not seem be very relevant.

Antigen-Antibody Complex↗
PubMedDate not supplied

[Infiltrating transitional carcinoma of the bladder. 3. Effect of regional lymph node dissemination on the prognosis].

The evolution of 168 patients, 136 of which underwent bilateral lymphadenectomy is analyzed in this paper. In 126 cases it was possible to obtain all the data in order to define N within the T.N.M. rating. With regard to the remaining patients 10, of which we lack the anatomopathological report, and 32 which did not undergo lymphadenectomy, are included under item Nx. During follow-up, metastasis was diagnosed in 60% node-positive patients. We believe it to have been already present at the time of undergoing surgery. Survival was significantly higher in the group without node dissemination than in both negative-nodes and Nx groups. When assessing the nodular dissemination group, patients treated with 2000 rad prior to cystectomy showed higher survival rates: 36% vs 22% and 11% for groups treated with 4500 rad and no radiotherapy. respectively. Metastatic percentage, however, was lower for the group managed with surgery alone (50%) than those treated with pre-operative radiotherapy (73% and 67% with 2000 and 4500 rad, respectively), on the other side, it would seem a contradiction that a 2000 rad dosage should be more effective than a 4500 rad dosage for this group of patients, since theoretically, the latter is closer to the ideal dosage to eradicate the nodular disease. Since 3 of 5 patients have micrometastasis, which we are yet unprepared to detect, all positive-node patients should receive chemotherapy immediately after recovery from surgery.

Antineoplastic Agents↗
PubMedDate not supplied

Influence of a single dose of ethanol on the kinetics of valproic acid in rats.

A study was made of the influence of ethanol on the kinetics of valproic acid (VPA) in rats that received single doses of both compounds. Three groups of animals received a single dose of VPA (100 mg/kg) through a gastric tube, alone (Group I: controls) or together with ethanol at doses of 2.5 mg/kg (Group IIa) and 5 mg/kg (Group IIb). VPA was determined using the homogeneous immunoassay EMIT. VPA kinetics were fitted to an open two-compartment model with a first order two phase absorption process defined by the constants Ka1 and Ka2, where Ka1 would reflect the rate of gastric emptying, and Ka2 could express the true absorption constant. The groups of animals receiving ethanol showed a statistically significant decrease (p less than 0.05) in plasma concentrations of VPA compared with the control group. Ka2 increased in groups IIa and IIb compared with the control group (35.79 hr-1 and 36.61 hr-1 vs. 28.18 hr-1). However, Ka1 decreased in group IIb as compared with the control rats (2.34 hr-1 vs. 4.18 hr-1), whereas no modifications were seen in group IIa (4.35 hr-1). The t1/2 beta was greater in groups IIa and IIb than in the controls (8.77 hr and 7.78 hr vs. 4.55 hr), and Ke was lower in those groups than in the controls (0.86 hr-1 and 0.48 hr-1 vs. 0.98 hr-1), suggesting a decrease in the elimination of VPA following administration of a single dose of ethanol.

Animals↗
PubMedDate not supplied

Mycobacterium genavense infection in canaries.

A case of mycobacteriosis in a collection of canaries (Serinus canarius) is described. The affected birds showed nonspecific clinical signs and macroscopic lesions (slight splenomegaly). Histologic lesions found in liver, spleen, lungs, and kidneys consisted of noncaseous nodules containing accumulations of large macrophages that showed a highly vacuolated cytoplasm in which numerous acid-fast organisms were detected. Attempts to isolate and culture the organisms using Löwenstein-Jensen and Coletsos media proved unsuccessful. Microorganisms belonging to the species Mycobacterium genavense were identified by means of polymerase chain reaction techniques in hepatic tissue from both birds. This finding confirms the existence of fastidiously growing mycobacterial infections, other than Mycobacterium avium, in birds.

Animals↗