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Biomedical subjects

S Díaz

Publications and source records attributed to S Díaz.

126 records · Page 7Linked to original sources
PubMedDate not supplied

Vaginal rings for contraception in lactating women.

Contraceptive methods for breastfeeding women should be safe for the mother and infant and should not interfere with lactation. Progestin-only methods meet these conditions and can be used from the sixth week postpartum. Because all progestins are excreted in milk, those that are insufficiently active by the oral route are preferable to avoid any possible effect on the baby. These steroids, however, must be administered to the mother by a non-oral route. Initially, progesterone was administered subdermally to test this concept. Subsequently, a progesterone vaginal ring was developed to be used continuously for 3 to 4 months and replaced with a new device, as needed, until weaning. Clinical trials have shown a high contraceptive efficacy (over 98.5%) and safety. The gross continuation rate of this method is approximately 40% at 12 months of use, with use-related problems being the main reason for discontinuation (26.8%). Currently, a Nestorone vaginal ring is under development, delivering 50 microg of Nestorone per day. It may be used continuously for up to one year, even if weaning occurs earlier. Both of these progestin-only rings prolong lactational amenorrhea to 10 to 12 months, which represents a health benefit and convenience for many women. The registration of the progesterone vaginal ring, developed as a contraceptive method to be used exclusively during lactation, has been approved in Chile and Perú. The fact that it is a user-controlled long-term contraceptive that delivers a natural hormone makes it an attractive option for many women.

Administration, Intravaginal↗
PubMedDate not supplied

Relationship between pathogenesis and immune regulation mechanisms in histoplasmosis: a hypothetical approach.

The cellular immune response may be the principal mechanism of defense against infection with Histoplasma capsulatum. Subsequently, regulation of cell-mediated immunity could be fundamental to the outcome of disease. Suppressive phenomena-present in the host before infection or brought about by fungal components-would explain the various courses of infection. The fact that high titers of antibodies are associated with a poor cellular response suggests that antibodies may have a role as "regulatory molecules" in histoplasmosis. Antibodies may modulate the expression of the cellular response either by direct inhibition or by activation of the suppressor cell population, thereby interfering with the infectious process.

Animals↗
PubMedDate not supplied

Simulation of ozone depletion using ambient irradiance supplemented with UV lamps.

In studies of the biological effects of UV radiation, ozone depletion can be mimicked by performing the study under ambient conditions and adding radiation with UV-B lamps. We evaluated this methodology at three different locations along a latitudinal gradient: Rimouski (Canada), Ubatuba (Brazil) and Ushuaia (Argentina). Experiments of the effect of potential ozone depletion on marine ecosystems were carried out in large outdoor enclosures (mesocosms). In all locations we simulated irradiances corresponding to 60% ozone depletion, which may produce a 130-1900% increase in 305 nm irradiance at noon, depending on site and season. Supplementation with a fixed percentage of ambient irradiance provides a better simulation of irradiance increase due to ozone depletion than supplementation with a fixed irradiance value, particularly near sunrise and sunset or under cloudy skies. Calculations performed for Ushuaia showed that, on very cloudy days, supplementation by the square-wave method may produce unrealistic irradiances. Differences between the spectra of the calculated supplementing irradiance and the lamp for a given site and date will be a function of the time of day and may become more or less pronounced according to the biological weighting function of the effect under study.

Canada↗
PubMedDate not supplied

[Improved oxygenation with nitric oxide treatment for hepatopulmonary syndrome after a liver transplant].

A 37-year-old man with cirrhosis of the liver hospitalized for orthotopic liver transplant (OLT) was found to have hepatopulmonary syndrome (HPS) during routine presurgical assessment. No problems with oxygenation developed during surgery. In the early recovery period, however, hypoxemia was observed to be uncorrected in spite of gradual normalization of liver function tests. OLT sometimes corrects HPS and, therefore, hypoxemia. However, significant decreases in oxygenation during recovery have been reported to affect patient morbidity and mortality. We therefore started low-dose nitric oxide (NO) inhalation once other possible causes of hypoxemia had been ruled out. Oxygenation improved, allowing tubes to be removed. Seven months after OLT, home oxygen therapy was still required to treat basal hypoxemia. HPS persisted, as confirmed by echocardiogram. Inhaled NO contributed to maintenance of adequate oxygenation during the early postoperative period, as essential for long-term survival in patients with HPS who undergo OLT.

Adult↗
PubMedDate not supplied

Voice restoration after total laryngectomy with tracheoesophageal puncture and voice prosthesis.

Removal of the voice box or larynx is the usual treatment for advanced cancer of the larynx. Tracheoesophageal puncture (TEP) has become an accepted method for voice restoration following total laryngectomy. Eleven patients under went total laryngectomy with TEP at San Pablo Hospital Medical Center between March 1989 and October 1995. Seven patients were available for voice analysis. Eighty six percent of the patient was able to talk. This is the first report of TEP being perform in Puerto Rico and with a complete Hispanic population of patients. Results compare favorably with those reported in the medical literature.

Aged↗
PubMedDate not supplied

[Gastric schwannoma. Report of a case].

Gastric schwannoma is a rare and benign neurogenic tumor. Diagnosis of this entity is uncertain previous to surgery, being this tumor localized in the sub-mucosa. Final diagnosis is achieved by surgical removal and histological examination.

Humans↗
PubMedDate not supplied

Chloramphenicol extraction from milk by using the diphasic dialysis method followed by liquid chromatographic determination.

An economical, fast, and simple method for the extraction and liquid chromatographic determination of chloramphenicol (CAP) in milk is described. CAP is extracted by using a recently developed membrane-based method named "diphasic dialysis." CAP is detected and quantitated in the organic solvent used in dialysis without additional cleanup steps by reversed-phase liquid chromatography and UV detection (270 nm). The determination limit of CAP in milk was about 5 micrograms/L, although as little as 1 microgram/L could be detected under optimal working conditions.

Animals↗
PubMedDate not supplied

Value of the peak expiratory flow in bronchodynamic tests.

OBJECTIVE: To determine the accuracy of the peak expiratory flow (PEF) as an alternative parameter to the forced expiratory volume at first second (FEV1) in the bronchodynamic tests. METHODOLOGY: We studied 84 patients, 53 males and 31 females, with average age 46 +/- 13 years, as clinic suspects of bronchial asthma. PEF was determined with a "mini-Wright peak flow meter" and a spirometry was obtained. Based on the results, 44 subjects were classified under group 1 (FEV1/FVC < 70% and FEV1 < 80% of theoretic value) and subjected to a bronchodilator test. While in group 2 subjects (normal spirometry), a methacholine challenge was performed. During each procedure, PEF readings were obtained before FEV1 determination. The usefulness of the PEF for the diagnosis of reversibility or bronchial obstruction with respect to the FEV1 was assessed in both groups. RESULTS: In the bronchodilator tests, a cut-off point was found for the increase in the PEF > 18%, which showed a sensitivity of 85%, specificity of 79%, positive predictive value of 77% and negative predictive value of 86%, with respect to an increase in the FEV1 > 15%. In the methacholine challenge, a decrease in the PEF > 12% only achieved a sensitivity of 74% and specificity of 71%. CONCLUSION: Peak expiratory flow may be an useful parameter in bronchodilator tests. However, it should not be used in methacholine challenge.

Adolescent↗