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Biomedical subjects

J Fuentes

Publications and source records attributed to J Fuentes.

At least 73 records · Page 4Linked to original sources
PubMed1983

Modifications of dynamic and static behavior by small-length perturbations in crayfish stretch receptor organs.

To investigate whether static and dynamic sensitivities of slowly and rapidly adapting stretch receptor organs (SAO and RAO, respectively) or crayfish are different when perturbed compared with those in conventional laboratory experiments, receptors were submitted to ramplike length changes of different velocities separated by long-duration, constant lengths of different values. They were perturbed at random by fast, small-amplitude length variations called "jitter." First-order afferent discharges were recorded extracellularly. Quantifications involved the separate estimation of static and dynamic response components. In the SAO, jitter (1) augmented the static sensitivity, (2) decreased the dynamic sensitivity, (3) simplified response profiles by decreasing nonlinearities and increasing transduction fidelity in terms of coding length. In the RAO, jitter (1) changed the behavior from phasic to tonic with length sensitivity, (2) decreased the dynamic sensitivity to values close to those of the unperturbed SAO, (3) increased transduction fidelity for stimulus length and decreased nonlinearities. Perturbation effects suggest that differences between SAO and RAO are more quantitative than qualitative. Moreover, they have general implications and are relevant to other mechanoreceptors at other levels in the CNS.

Animals↗
PubMed1981

Simulation of post-synaptic activities in hippocampal cells during theta rhythm.

Three types of discharge patterns can be recorded from hippocampal cells during theta rhythm. The Type 1 discharges are in rhythmic bursts phase-locked with theta; the Type 2 pattern, although non-rhythmic shows a phase relationship with theta; and the Type 3 activity is non-rhythmic and unrelated with theta. Furthermore, depending on the presence or absence of theta and on other undetermined factors, units with Type 1 activity may become non-rhythmic or vice-versa. These patterns may derive from the relative amounts of rhythmic versus non-rhythmic inputs received by each cell. This possibility was tested through computer simulation of a hypothetical neuron receiving random and rhythmic inputs. The inputs produced membrane potential (MP) variations simulated as a band-limited gaussian white noise (WN) and a sinewave, respectively, which were summated by the cell. Spiked were triggered when a MP threshold was reached. The simulated neuron exhibited the three types of discharge patterns by changing the sinewave to WN ration. Ratios of 0.4 and 0.1 generated Types 1 and 2 behavior, respectively, and lower ratios Type 3. Statistical methods, based on autocorrelations and averages, were used to assess rhythmicities and relationships between spiked and EEG or the simulated MP. The simulation supports the tested hypothesis, provides a good description of the possible mechanisms involved and is predictive, indicating that most hippocampal cells, rhythmic or not might show periodic MP oscillations phase-locked with theta.

Animals↗
PubMed1980

Ketoconazole in paracoccidioidomycosis: efficacy of prolonged oral therapy.

Ketoconazole, a new oral imidazole derivative, was employed for the treatment of five patients with paracoccidioidomycosis. The response was excellent, with objective clinical improvement and healing of both mucocutaneous and pulmonary lesions. Mycological and serological tests, as well as delayed hypersensitivity, were assessed and found to correlate with clinical improvement. Therapy was conducted for 12 months with a dose of 200 mg day in 2 patients; in the remainder the dose was reduced (100 mg day) after the first 6 months and maintained as such for an equal period. No side-effects or toxicity were noted despite prolonged treatment. The advantages of the new therapeutic approach are discussed.

Administration, Oral↗
PubMed1979

Ketoconazole, an oral antifungal: laboratory and clinical assessment of imidazole drugs.

Miconazole, a parenterally administered imidazole antifungal agent has been shown to produce responses in systemic fungal infections in man. Ketoconazole, an analogue, can be given by mouth. It is inhibitory in vitro at low concentrations to most fungi. Blood levels after oral administration to animals and man greatly exceed these inhibitory concentrations for several hours. The efficacy of this drug has been demonstrated in animal models. Initial clinical evaluation has produced responses to therapy with 200-400 mg/day in 13 of 16 evaluable patients with systemic and superficial fungal infections, involving 10 fungal pathogens. No toxicity has been noted to date in these human studies. Ketoconazole is a promising agent needing further extensive evaluation.

Adolescent↗
PubMedDate not supplied

Ketoconazole: a new drug for the treatment of paracoccidioidomycosis.

Ketoconazole was administered orally to 13 patients with paracoccidioidomycosis. Therapy consisted of 200 mg per day for periods ranging from three to 12 months. All patients improved markedly, with healing of pulmonary, mucosal, and skin lesions. Patients exhibiting the latter two manifestations began to improve two weeks after therapy, and healing occurred within three months. Pulmonary lesions regressed at a slower pace and healed by fibrosis. Mycologic tests have corroborated the clinical improvement. Adverse effects were not observed; monitoring of renal, hematologic, and hepatic functions did not reveal any abnormalities. Five patients completed a year of therapy and were free of symptoms when therapy was discontinued. Of these patients, four were followed for several months and had no relapses; the fifth patient developed tuberculosis and died. The results indicate that ketoconazole is a safe and effective drug for therapy in the treatment of paracoccidioidomycosis.

Adult↗