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Biomedical subjects

M Rivera

Publications and source records attributed to M Rivera.

At least 217 records · Page 12Linked to original sources
PubMed1977

IUD insertions by midwives: five years' experience in Santiago, Chile.

This report includes data on insertions of Lippes Loop D, Copper-7, and Copper-T intrauterine devices (IUDs) performed by certified nurse-midwives and physicians with comparable levels of training and experience in inserting IUDs. Net 1-year pregnancy, expulsion, and removal rates were used to compare the experiences of the 2 groups. There were no significant differences between the groups in most of the event rates or in the overall method discontinuation rates. The authors conclude that, with adequate training and experience, nurse-midwives can provide this family planning service with no additional risk to patients.

Chile↗
PubMed1976

The clinical efficacy of the repeated transcervical instillation of quinacrine for female sterilization.

The safety and efficacy of the repeated transcervical instillation of quinacrine hydrochloride in a suspension of 5 ml of 2% Xylocaine was evaluated in 200 patients. All instillation procedures were performed during the proliferative phase of the menstrual cycle: the second instillation was made in the first menstrual cycle following the initial instillation and the third and last instillation at 6 months after the first. None of the patients used any adjunctive contraceptives. Follow-up visits were scheduled at 6-month intervals after the last instillation. The potentially serious complications following the instillation were four cases of cortical exitation, and one case of acute adnexitis. The second instillation was not performed for 16.0% and the third instillation was not performed for 16.7% of the patients, for medical and/or personal reasons. Fifty-one pregnancies were reported, 41 (80.4%) before completion of the three instillations. The results of this study show that the instillation schedule used is unsatisfactory for widespread use. Additional studies are currently being conducted to evaluate the use of an adjunctive contraceptive up to the time of the third instillation in order to reduce the high pregnancy rate.

Adult↗
PubMed1972

Interrelationship and control of glucose metabolism and lipogenesis in isolated fat-cells. Effect of the amount of glucose uptake on the rates of the pentose phosphate cycle and of fatty acid synthesis.

In order to study the quantitative relationship between fatty acid synthesis and pentose phosphate-cycle activity under different hormonal and dietary conditions affecting the extent of glucose uptake, cells isolated from rat epididymal adipose tissue were incubated in bicarbonate buffer containing [U-(14)C]-, [1-(14)C]- or [6-(14)C]-glucose. From the amount of glucose taken up, the production of lactate and pyruvate, and the incorporation of (14)C from differently labelled [(14)C]glucose into CO(2), fatty acids and glyceride glycerol, the rates of glucose metabolism via different pathways and the extent of lipogenesis under various experimental conditions were determined. The contribution of the pentose phosphate-cycle to glucose metabolism under normal conditions was calculated to be 8%. Starvation and re-feeding, and the presence of insulin, caused an enhancement of glucose uptake, pentose phosphate-cycle activity and fatty acid synthesis. Plots of both pentose phosphate-cycle activity and fatty acid synthesis versus glucose uptake revealed that the extent of glucose uptake, over a wide range, determines the rates of fatty acid synthesis and glucose metabolism via the pentose phosphate cycle. A balance of formation and production of nicotinamide nucleotides in the cytoplasm was established. The total amount of cytoplasmic NADH and NADPH formed was only in slight excess over the hydrogen equivalents required for the synthesis of fatty acids, glyceride glycerol and lactate. Except in cells from starved animals, the pentose phosphate cycle was found to provide only about 60% of the NADPH required for fatty acid synthesis. The results are discussed with respect to an overall control of the different metabolic and biosynthetic reactions in the fat-cells by the amount of glucose transported into the cell.

Adipose Tissue↗
PubMed1972

Interrelationship and control of glucose metabolism and lipogenesis in isolated fat-cells. Control of pentose phosphate-cycle activity by cellular requirement for reduced nicotinamide adenine dinucleotide phosphate.

By using inhibitors and stimulators of different metabolic pathways the interdependence of the pentose phosphate cycle and lipogenesis in isolated fat-cells was studied. Rotenone, which is known to inhibit electron transport in the respiratory chain, blocked glucose breakdown at the site of pyruvate dehydrogenase. Consequently, because of the lack of acetyl-CoA, fatty acid synthesis was almost abolished. A concomitant decrease in pentose phosphate-cycle activity was observed. Phenazine methosulphate stimulated pentose phosphate-cycle activity about five- to ten-fold without a considerable effect on fatty acid synthesis. The influence of rotenone on both the pentose phosphate cycle and lipogenesis could be overcome by addition of phenazine methosulphate, indicating that rotenone has no direct effect on these pathways. The decreased rate of the pentose phosphate cycle in the presence of rotenone therefore has to be considered as a consequence of decreased fatty acid synthesis. The rate of glucose catabolism via the pentose phosphate cycle in adipocytes appears to be determined by the requirement of NADPH for lipogenesis. Treatment of cells with 6-aminonicotinamide caused an accumulation of 6-phosphogluconate, indicating an inhibition of 6-phosphogluconate dehydrogenase. The rate of glucose metabolism via the pentose phosphate cycle as well as the rate of fatty acid synthesis, however, was not affected by 6-aminonicotinamide treatment and could still be stimulated by addition of insulin. Since even in cells from starved animals, in which the pentose phosphate-cycle activity is extremely low, no accumulation of 6-phosphogluconate was observed, it is concluded that the control of this pathway is achieved by the rate of regeneration of NADP at the site of glucose 6-phosphate dehydrogenase.

Adipose Tissue↗
PubMedDate not supplied

Comparative IUD study: Lippes Loop D, Dalkon Shield and TCu-200.

A study was undertaken to look at the clinical behavior of the Dalkon Shield, the Lippes Loop D and the TCu-200 inserted by physicians and midwives. Differences among the three devices were not statistically significant, although lower expulsion rates and higher pregnancy rates were reported for the Dalkon Shield. No differences were observed between insertions performed by physicians and those performed by midwives; this emphasizes the efficiency of using paramedical personnel in the field of intrauterine contraception.

Adult↗