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Biomedical subjects

R Rivera

Publications and source records attributed to R Rivera.

At least 91 records · Page 5Linked to original sources
PubMed1992

Oral tolerance impairment in mice with staphylococci-induced wasting syndrome.

The effects of staphylococci-induced experimental wasting disease on the immune response of 1 month old CD1 mice were investigated. Animals were separated into different subgroups in order to study their cellular immune competence. Malnutrition of wasted mice was associated with anorexia, diarrhea and weakness. Footpad-injected splenic cells produced normal graft vs. host (GvH) reactions in the popliteal lymph nodes of F1 hybrids. In other experiments, the SRBC intragastric feeding of wasted mice did not cause a tolerant anti-erythrocyte humoral immune response. Three weeks after the staphylococci injections, convalescent erythrocyte-fed wasted mice exhibited an anti-SRBC PFC production similar to that observed in non-tolerant immunized control healthy mice. In return, healthy SRBC-fed control mice showed the specific attenuation of antibody response characteristics of oral tolerance. Differences were found between the immune competence of the undernourished staphylococci-treated wasted mice and those shown by other authors in protein-depleted mice.

Administration, Oral↗
PubMed1992

[The propedeutic course given at the School of Medicine and the academic performance of the students that passed it].

A report of the results of the Propedeutic Course in the Medical School of the University of Panama is informed. This course was established by the Academic Council, at the request of the Medical School, to diminish the registration form 280 to 180 students, taking into account the low academic performance of the students with the lowest grades in the Admission Process. The study showed that the correlation indices of the students in the Propedeutic Course and in the first regular semester was low. The study also showed that the number of students from the Propedeutic Course who repeated or were separated from the school, was higher than those from the regular semester.

Curriculum↗
PubMed1992

[Course and prognostic value of nutritional parameters in chronic bronchitis].

We studied the nutritional parameters in 82 patients with chronic airways obstruction (type chronic bronchitis). Midarm muscle circumference was the earliest parameter affected. Patients were admitted to the hospital when his serum albumin had a value under normal. On the other hand, the outpatients had a serum albumin within the normal limits. When the protein deficiency involved serum prealbumin and serum retinol binding protein the patients were admitted to intensive care unit (ICU). The body weight and triceps skinfold were within the normal limits even in icu's patients, so that, both parameters neither reflect the nutrition status nor the severity of the undernutrition.

Aged↗
PubMed1991

Timing of postpartum tubal sterilization using the Filshie clips: an analysis of data from two developing-country centers.

Two-hundred-ninety-seven women at a Panamanian center and 148 women at a Philippine center had their tubal sterilization performed during their postpartum hospital stay after an uncomplicated vaginal delivery of a live birth. The sterilizations were all performed with the use of the Filshie clip via minilaparotomy. The timing of the sterilization varied from two hours to six days after delivery. At each of the two centers, women sterilized within 48 hours after delivery were compared with those sterilized at 49 or more hours with respect to surgical difficulties, tubal injuries, complications/complaints, technical failures and lengths of hospitalization after sterilization and before discharge. The one-year gross cumulative pregnancy rates were also compared. No significant differences were detected in any of the above outcome variables between the two timing groups at each center. While the data suggest that tubal sterilizations by the Filshie clip performed two to six days following childbirth are as safe and effective as those performed within 48 hours of delivery, further studies are urged.

Developing Countries↗
PubMed1990

Is the copper T 380A device associated with an increased risk of removal due to bleeding and/or pain? An analysis.

Previous studies have consistently shown that the family of the Copper T 380 devices is more effective in preventing accidental pregnancies than the inert, as well as most other, if not all, copper devices. However, a number of these studies also reported a higher removal rate due to bleeding and/or pain for the TCu 380A than for other devices. The programmatical importance of these findings prompted us to analyze the international multi-center randomized clinical trial datasets to examine this question on the new TCu 380A (ParaGard) recently marketed in the U.S. Our results, while confirming the inherent superior efficacy of the TCu 380A, did not reveal a significantly higher removal rate because of bleeding and/or pain among TCu 380A users than among users of the comparative devices, which included the Lippes Loop D, the TCu 200, the TCu 220 and the Multiload Cu 250 devices.

Adolescent↗
PubMed1990

[Propedeutic course in the medical school at Panama University in 1989].

An analysis was made of the data necessary to establish a pre-university propaedeutic course in the Faculty of Medicine of the University of Panama, and its qualitative and quantitative evaluation of the results obtained. The necessity to select the students who wished to enroll in the faculty of medicine was demonstrated because of the failing of the student, whichever was due to inclination, aptitude or scientific knowledge. This is in order to avoid that the student incorrectly chooses a course in which he could not successfully study.

College Admission Test↗
PubMed1990

[Consequences of bacterial product interaction with the immune system in newborn mice].

The immunological competence of a newborn mice group, inoculated with a heat killed suspension of staphylococci, was studied to find out if the treated mice preserved the immunological competence of the T lymphocytes, for induce an allograft. A group of CD1 newborn male mice were injected intraperitoneally with the bacterial suspension, every three days during a four weeks period. Other group received only isotonic saline solution. The lymphocyte ability to form hemolytic plaques and their capacity to provoke a local graft-versus-host reaction in F1 receptor animals was studied in both groups. The results showed that the staphylococci treated newborn mice had a decreased capacity to form anti-erythrocyte antibodies without modification in their reactivity against histoincompatible antigens. Newborn mice, runting-like disease; bacterial inoculation; immunological response in.

Animals↗
PubMed1989

Insertional pain and other IUD insertion-related rare events for breastfeeding and non-breastfeeding women--a decade's experience in developing countries.

The possible effect of breastfeeding on intrauterine device (IUD) insertion events was investigated. Analysis included a total of 6493 women who enrolled in multicenter IUD clinical trials over a ten-year period. Findings indicate that breastfeeding exerts a protective effect on the incidence of moderate to severe insertional pain and reduces the need for cervical dilatation to facilitate insertion. The pain protection effect was most evident in breastfeeding women who were still in lactational amenorrhea. Subjects with amenorrhea, both breastfeeding and non-breastfeeding, had a significantly lower incidence of pain at IUD insertion than the corresponding menstruating subjects. This effect may be related to a higher secretion of beta-endorphin in the breastfeeding and lactational amenorrheic subjects.

Breast Feeding↗
PubMed1989

Menstrual patterns and progesterone circulating levels following different procedures of tubal occlusion.

This study was undertaken to assess the effects of different tubal occlusion procedures on ovarian function. Three groups of subjects randomized to tubal occlusion by laparoscopy and Yoon ring (24 subjects), minilaparotomy and Yoon ring (19 subjects) and minilaparotomy and Pomeroy (22 subjects), and one separate control group of 26 healthy subjects not using any form of contraception were studied in a prospective design. The characteristics of the menstrual patterns were studied for one year after sterilization. Determination of the circulating progesterone levels were made on days 15, 20 and 25 of menstrual cycles initiated 1, 3, 6 and 12 months following the tubal ligation. In the analysis of the bleeding pattern there was a statistically significant difference in the mean segment length and in the longest bleeding-free interval in the subjects who had been sterilized by minilaparotomy with Yoon ring, when compared to the other two study groups and to the control group. However, the magnitude of this difference in number of days was not considered clinically significant. There was no statistically significant difference in the percentage of ovulatory cycles within the study and the control groups, or when the results of the study groups were compared with each other or to the control group.

Adult↗
PubMed1989

Consensus statement on the use of breastfeeding as a family planning method.

An interdisciplinary international group of researchers in the area of lactational infertility gathered with the purpose of coming to a consensus about the conditions under which breastfeeding can be used as a safe and effective method of family planning. The consensus of the group was that the maximum birth spacing effect of breastfeeding is achieved when a mother "fully" or nearly fully breastfeeds and remains amenorrheic. When these two conditions are fulfilled, breastfeeding provides more than 98% protection from pregnancy in the first six months. Data are reviewed from thirteen prospective studies in both developed and developing countries supporting the consensus. The rationale for the consensus is given in detail. Recommendations are made based on what is currently known of the antifertility effects of breastfeeding. Research should continue to measure a broad spectrum of variables so that these guidelines can be refined as new information becomes available.

Breast Feeding↗
PubMed1989

Estrogen-progestogen once-a-month injectable contraceptives and serum prolactin.

To assess the effect of hormonal monthly injectable contraceptives upon the serum values of immunoreactive prolactin (Prl), three groups of women of reproductive age exposed to different estrogen-progestogen injectable formulation for a minimum of one year were studied. The first group (n = 10) received dihydroxyprogesterone acetophenide 150 mg and estradiol enanthate 10 mg (DHPA/E2-EN), Group 2 (n = 21) received medroxyprogesterone acetate 25 mg and estradiol cypionate 5 mg (MPA/E2-C) and Group 3 (n = 19) was exposed to norethisterone enanthate 50 mg and estradiol valerate 5 mg (NET-EN/E2-V). A group of IUD users (n = 16) served as the control group. Serum Prl and 17 beta-estradiol (E2) concentration were determined in blood samples (0 and 15 min.) on days 0 (day of last injection), 10, 20 and 30 after last contraceptive injection. The results demonstrated a slight though not significant increase (p greater than 0.05) in serum Prl in the three experimental groups as compared with the IUD control group. This increase in Prl levels observed on day 10 post-last injection never exceeded the upper limits of the normal range (20 ng/ml). Overall, the data demonstrated that the chronic administration of these estrogen/progestogen once-a-month injectable contraceptives does not affect the Prl baseline secretion in women.

Adult↗
PubMed1989

A technique to control the deleterious effects of retrograde blood flow and to improve myocardial protection in surgery of acute dissection of the ascending aorta.

In surgery of the acute dissection of the ascending aorta, a technique is described for routine cannulation through a Dacron graft in order to produce antegrade flow in the true aortic lumen and higher pressures than in the false lumen. This is a useful method to avoid the deleterious effects of the retrograde blood flow through the false lumen, when femoral cannulation is used, as well as to improve the myocardial protection by reperfusing the myocardium while the graft distal end anastomosis is carried out.

Anastomosis, Surgical↗
PubMed1989

A comparative evaluation of the safety and contraceptive effectiveness of 65 mg and 100 mg of 90-day norethindrone (NET) injectable microspheres: a multicenter study.

The first of a second generation of slow-release injectable contraceptives is the norethindrone (NET) microspheres with a 90-day duration of action. It was evaluated at 65-mg and 100-mg doses for safety and contraceptive effectiveness in two randomized, single-blind trials among 131 women: 94 women for 12 months and 37 women for 6 months. The 6-month trial included additional evaluations of ovarian function and serum NET values. In the 6-month trial, no indication of ovulation was detected in the 100-mg dose group, while 3 of the 19 women in the 65-mg group showed signs of ovulation (progesterone greater than 3 ng/ml). No pregnancies were reported in the 100-mg group and one pregnancy in the 65-mg group resulted in a life-table pregnancy rate for that dose of 2.6 per 100 woman-years (95% confidence interval, 0 to 7.5). Days of vaginal bleeding were analyzed for 30 days before treatment and in 90-day reference periods after treatment. The mean number of vaginal bleeding and spotting days increased initially after the first injection in both dose groups, but decreased to below baseline in both dose groups after 6 months. The two doses appear comparable in clinical safety, side effects, vaginal bleeding patterns, and laboratory measures. With the preliminary estimate of efficacy, the 65-mg dose would be the minimally effective dose for the NET 90-day injectable contraceptive.

Adult↗
PubMed1988

Expanded use of the right and left internal mammary arteries for myocardial revascularization.

While the use of the left internal mammary artery (IMA) has become routine in many cardiac surgery units there is some reluctance to utilize the right IMA. The reasons for this are the higher morbidity and mortality observed in the initial experience with bilateral IMA grafting, the limited length of the right IMA, and its potential injury in reoperations when used to revascularize the left anterior descending artery. In this series of 50 patients the right IMA was used as a conduit for myocardial revascularization. One hundred and fifty-nine coronary vessels were grafted (3.2 per patient) 67.3% with IMA and only 32.7% with vein grafts. The right IMA was used for 51 anastomoses and the left for 56, either as simple, sequential or Y type grafts. The refinement of techniques for constructing the IMA grafts used in this series show that the right IMA can reach in most of the cases the anastomotic sites of the right coronary artery beyond the acute margin of the heart, and it is hoped that the lateral positioning of the IMA pedicles will lessen the chance of graft injury at reoperation. On the basis of early clinical results (2% mortality and 4% sternal complications), the application of the right IMA seems justified electively for the revascularization of both left and right coronary artery systems or as a free graft in conjunction with the left IMA.

Adult↗