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Biomedical subjects

R Rivera

Publications and source records attributed to R Rivera.

At least 109 records · Page 6Linked to original sources
PubMed1988

Breast-feeding and the return to ovulation in Durango, Mexico.

Twenty-nine breast-feeding mothers and 10 non-breast-feeding postpartum comparison mothers from a rural area of Mexico were followed longitudinally until ovulation resumed. A simple set of guidelines is described involving three obvious milestones for the breast-feeding mother to safely use the natural contraceptive benefit of breast-feeding. Those milestones are: the first vaginal bleeding episode, the initiation of supplementation, and the child's monthly birthday. In the absence of bleeding and supplementation, 100% of breast-feeding mothers remained anovular for 3 months postpartum, 96% for 4 months, 96% for 5 months, and 96% for 6 months. This suggests that, if a mother understands these three conditions, she can use breast-feeding alone as effectively as modern family planning methods for the prevention of pregnancy.

Adolescent↗
PubMed1987

Norethisterone contraceptive microspheres.

Two formulations of polylactic and polyglycolic acid microcapsules containing 75 and 100 mg of NET respectively were studied for a 90-day period of anticipated contraceptive effect in two groups of five women. A 200 mg dose of NET preparation was also studied for a 180-day period of anticipated contraceptive effect in 19 women. Alteration in menstrual cycle, with tendency to short bleeding episodes, spotting days, and amenorrhea were the most important collateral effects. In the majority of cases, ovulation was inhibited. No cases of pregnancy were presented. The obtained NET circulating levels were very stable during the period of anticipated contraceptive effect.

Contraception↗
PubMed1985

Early myocardial revascularization for postinfarction angina: results and long-term follow-up.

Within 30 days of acute myocardial infarction, 108 consecutive patients underwent urgent surgical myocardial revascularization for postinfarction angina between July 1976 and March 1983. There were 84 men and 24 women whose mean age was 59.6 +/- 9.5 years (range 34 to 80). Group I (15 patients, 14%) underwent surgery within 48 hours, Group II (47 patients, 43%) between 3 and 7 days and Group III (46 patients, 43%) within 30 days. Fifty-nine patients (55%) had transmural infarction. The ejection fraction was less than 40% in 21 patients (19%). Left ventricular end-diastolic pressure was 20 mm Hg or greater in 42 patients (39%). The incidence of single, double, triple vessel and 70% or greater left main coronary artery stenosis was 4, 20, 59 and 17%, respectively. There were two deaths (1.8%) within 30 days of operation. The incidence of intraaortic balloon pumping was higher in patients operated on earlier after myocardial infarction (53% of Group I versus 22% of Group III). Statistically, there were no differences in the use of inotropic agents or the occurrence of arrhythmias or postoperative myocardial infarction in the three groups. Late follow-up (mean 35 months, range 18 to 98) is complete for all patients (100%). There were four late myocardial infarctions and eight deaths. Actuarial survival was 87% at 5 years. Seventy-three percent of the 108 patients were free of angina and the condition of 14% improved. These results indicate that myocardial revascularization in the first 30 days after myocardial infarction can be accomplished with morbidity and mortality rates similar to those of an elective operation for chronic angina refractory to medical management.

Adult↗
PubMed1985

The kinetics of D3-3H metabolism in tropical sprue.

The metabolism of vitamin D3-3H was studied in a small group of controls and subjects with tropical sprue after the oral or intravenous administration of 8 to 10 microCi of D3-3H. The biological half life of D3-3H upon the administration of the isotope by the intravenous route was normal in 2 controls, very low in a subject with tropical sprue who had steatorrhea, and decreased in a subject with tropical sprue who did not present steatorrhea. After the administration of the isotope by the oral route, the biological half life was 35 hours in the control and no radioactivity could be detected in the plasma of the subject with tropical sprue who had steatorrhea. Twenty four hours after the intravenous dose the percentage of radioactivity in the plasma as HCC-3H was two times higher in the tropical sprue subjects than in the controls. When the dose was given orally the net absorption was 50.5% in the subject with tropical sprue and steatorrhea and 86.8% in the subject with tropical sprue who was partially treated. These results showed rapid clearance of the D3-3H in the subject with tropical sprue and steatorrhea indicating depletion of vitamin D stores in the tissues and decrease in the net absorption of the dose when given orally. The presence of a higher percentage of the dose in the plasma as HCC-3H after the intravenous and oral administrations in the tropical sprue subjects when compared to controls indicates that the diseased state does not alter vitamin D3 metabolism.

Administration, Oral↗
PubMed1985

Carpentier's flexible ring versus De Vega's annuloplasty. A prospective randomized study.

To compare the efficacy of Carpentier's tricuspid annuloplasty with De Vega's, we prospectively randomized 159 patients, operated upon between January, 1977, and January, 1980, to one of the two techniques: 76 patients were assigned to the Carpentier group and 83 to the De Vega group. The criterion for inclusion in the study was the presence of moderate to severe tricuspid regurgitation. There were no significant differences in mean age, male proportion, type of mitral lesion, incidence of aortic valvulopathy, and other preoperative and perioperative characteristics between the two groups. However, organic tricuspid damage on macroscopic intraoperative examination was more common in the Carpentier group. At the end of follow-up (average 64 months) in patients with satisfactory left heart hemodynamics, there was a significant difference in the incidence of moderate or severe tricuspid insufficiency between the two groups (De Vega, 14/41; Carpentier, 4/40; p less than 0.01). In 76 patients (40 with Carpentier's annuloplasty and 36 with De Vega's technique), contrast right ventriculography was performed postoperatively and the degree of tricuspid regurgitation assessed semiquantitatively. In both groups, control of tricuspid regurgitation was poor in patients with either high total pulmonary resistances or organic tricuspid damage. If patients with these characteristics are excluded, then significant tricuspid regurgitation was encountered in only one patient in the Carpentier group but in nine of 19 in the De Vega group (p less than 0.01). In conclusion, in the treatment of tricuspid regurgitation, better results are obtained with Carpentier's than with De Vega's annuloplasty, especially if there is no organic tricuspid damage and pulmonary resistances decrease postoperatively.

Adult↗