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Biomedical subjects

R Rivera

Publications and source records attributed to R Rivera.

At least 127 records · Page 7Linked to original sources
PubMed1984

The use of biodegradable norethisterone implants as a 6-month contraceptive system.

The effects of a 6-month contraceptive system of biodegradable norethisterone (NET) implants on the menstrual cycle, estradiol and progesterone levels, the presence of side effects, its contraceptive effectiveness, and the NET levels achieved were studied in a group of nine women. There was practically no disruption of the menstrual cycle and no important side effects. Ovulation was inhibited in four subjects, and another four subjects remained ovulatory. In all the subjects a cyclic secretion of estradiol was maintained. No pregnancies occurred. The circulatory levels of NET were very stable throughout the 6-month period of implant use.

Adult↗
PubMed1983

Treatment of adult acute lymphoblastic leukemia with adriamycin, vincristine, and prednisone.

At the present time, it is possible to achieve up to a 95% complete remission in childhood acute lymphoblastic leukemia, using the combination of vincristine and prednisone. Nevertheless, it has not been possible to reproduce these results in the adult. For this reason, a third drug, in this case adriamycin in a low dose, was added to the vincristine-prednisone combination in the treatment of adult acute lymphoblastic leukemia (ALL). Complete remission was achieved in 45 of the 50 patients (90%). The median duration of remission was 23 months and the median survival time in this group was 31 months. The complications were minimal and the tolerance was good. From the point of view of our results and others reported in the literature, we consider that the combination of vincristine, prednisone, and adriamycin is a useful method for induction of remission of adult ALL.

Adolescent↗
PubMed1983

The effects of three different regimens of oral contraceptives and three different intrauterine devices on the levels of hemoglobin, serum iron and iron binding capacity in anemic women.

The effects on hemoglobin, iron and iron binding capacity (IBC) in 150 moderately anemic women of 1) a 21-day low-dose combined pill, 2) the same low-dose combined pill for 21 days, followed by 7 days of an iron-containing pill, 3) the same low-dose combined pill administered for 63 consecutive days, followed by 7 days of no pill intake, 4) Lippes IUD, 5) TCu 220C and 6) Progestasert were studied. The three pill regimens were associated with an increase in hemoglobin and serum iron after 12 months. However, the iron pill and 63-day schedule groups produced an increase in hemoglobin and iron at the 6th month ans a diminution of IBC at 12 months. The Lippes and TCu 220C groups did not show any change in hemoglobin, iron or iron binding capacity after 12 months. The Progestasert group showed an increase in hemoglobin and iron levels at 6 and 12 months, and a diminution of IBC at 12 months. The pill and Progestasert have advantages as contraceptives in anemic women.

Adolescent↗
PubMed1983

The Medtronic-Hall prosthesis in multiple valve replacement--first results.

From January 1981 to September 1982, 107 patients have been operated on for valve replacement with the Medtronic-Hall (M-H) prosthesis. Thirty-four of them have had multiple valve replacements and they are the subject of this paper. In 2 cases there were tricuspid replacement, and in 9 other patients some type of tricuspid annuloplasty was performed. There were 2 hospital deaths (5.8%) and one late death. No thromboembolic episodes were recorded in this series of patients. In 2 instances a periprosthetic leak was detected. One of these was in a woman with an aortic and mitral valve replacement due to bacterial endocarditis. In this patient a diastolic aortic murmur was registered 4 months after the operation without hemodynamic repercussion. The other patient had endocarditis with positive blood cultures (S. epidermidis) one year after the operation and showed severe hemodynamic deterioration. The patient was re-operated on and the mitral prosthesis was replaced by another with the same characteristics. The patient is doing well. A constant but slight degree of hemolysis was found in every patient in the group.

Adult↗
PubMed1982

Prediction of urinary excretion of 131I-orthoiodohippurate.

A new formula is presented for the prediction of urinary excretion at approximately 35 min after injection of 131I-orthoiodohippurate, derived from a large series of normal kidney donors, before and after unilateral nephrectomy, and a few patients with diseases in which there was no evidence of urinary tract obstruction. The best formula was: Expected percent dose excretion at 35 min = 79.3[1-e--(0.004798 X ERPF)] with a standard error of estimate (Sy.x) of 5.2% dose. This value has been particularly useful in clinical practice in the calculation of an excretion index (actual/expected percent dose excretion) which separates various post-transplantation entities and various nephrourologic processes.

Humans↗
PubMed1982

Bioavailability of iron- and copper-supplemented milk for Mexican school children.

Fortification of dairy products with trace metals requires use of assimilable compounds that do not catalyze off-flavors due to lipid peroxidation but show good biological availability. The Fe(III) and Cu(II) chelates of the promising chelator, lactobionic acid, have been compared to Fe(II) and Cu(II) salts for their ability to improve hematological status in a mildly anemic population. Fe- and Cu-fortified cow milk was administered to children (aged 6 to 15) in the Durango, Mexico, "school lunch" program. Children drank milk providing 20 mg Fe and 3 mg Cu as ferric/cupric lactobionate ("chelate") or ferrous/cupric chloride ("salt") for 5 of 7 days/wk for 3 months. Supplementation with "salt" and "chelate" raised Hb significantly by 1 and 0.3 g/dl, respectively, above the control (unsupplemented) group. No significant change was observed in incremental serum ferritin, serum Fe, or transferrin saturation, or in final serum Cu. Ferric lactobionate shows poorer bioavailability than ferrous ion in the presence of Cu, but milk can be an excellent vehicle for Fe or Cu supplementation.

Adolescent↗
PubMed1982

High pressure liquid chromatographic determination of mono- and disaccharides in presweetened cereals: Collaborative study.

A collaborative study was conducted using a modified AOAC method (sugars in chocolate) for the determination of fructose, glucose, sucrose, and maltose in presweetened cereals by high pressure liquid chromatography (HPLC). Eight samples consisting of 6 products were analyzed in duplicate by the HPLC method and the AOAC Lane-Eynon method. The AOAC method was modified to use water-alcohol (1 + 1) and Sep-Pak C18 cartridges for sample cleanup. The HPLC results indicate precision comparable to the lane-Eynon method and the chocolate method. The modified HPLC method has been adopted official first action.

Chromatography, High Pressure Liquid↗
PubMed1982

Hemodynamic evaluation of the Angell-Shiley porcine xenograft.

The Angell-Shiley porcine xenograft was evaluated in 48 asymptomatic subjects who underwent cardiac catheterization an average of 14 months after operation. Nineteen patients had mitral and 29 had aortic valve replacement. The average mitral valve gradient was 8 +/- 3 mm Hg and the average effective orifice area was 1.8 +/- 0.6 cm2. The average aortic valve gradient was 22 +/- 7 mm Hg and the average effective orifice area was 1.2 +/- 0.3 cm2. During supine leg exercise, the average mitral valve gradient increased to 12 +/- 4 mm Hg (p less than 0.001) and the average aortic valve gradient increased to 27 +/- 8 mm Hg (p less than 0.001) compared to findings at rest. On the basis of data obtained with a regression analysis model, there is a high probability that an Angell-Shiley aortic xenograft with a stent diameter less than 25 mm will have a postoperative effective orifice area of less than 1 cm2, and that an Angell-Shiley mitral xenograft with a stent diameter less than 30 mm will have a postoperative effective orifice area of less than 1.5 cm2. Our data suggest that the Angell-Shiley xenograft has suboptimal hemodynamic performance in stent sizes less than 30 mm in the mitral position and less than 25 mm in the aortic position.

Adult↗
PubMed1981

Hepatoma presenting as a retro-orbital metastasis.

Patients with hepatomas who present primarily with symptoms of metastatic disease are rare. A case is described of a patient whose initial manifestation of disease was related to a retro-orbital mass. The literature concerning orbital metastases is reviewed.

Carcinoma, Hepatocellular↗
PubMed1981

Lack of greater seroconversion of rhesus monkeys after subcutaneous inoculation of dengue type 2 live-virus vaccine combined with infection-enhancing antibodies.

Four groups of six nonimmune male rhesus monkeys were inoculated subcutaneously with formulations of dengue type 2 vaccine virus DEN-2/S-1. Group A received 1.9 x 10(4) plaque-forming units of vaccine in normal human serum albumin diluent. Group B received the same dose combined with a dengue type 2-immune human serum diluted 1:1,600, beyond its neutralization endpoint of 1:300, but having an immune enhancement titer of 250,000. Groups C and D received 10-fold dilutions of these respective formulations. No migration-inhibitory factor was found when peripheral blood mononuclear leukocytes obtained on day 68 post-immunization from monkeys of all experimental groups were tested. No viremia was detected in any of the monkeys when sera taken on postvaccination days 1 through 12 were inoculated into adult Toxorhynchites amboinensis mosquitoes and LLC-MK2 cells. By day 89, four of the six monkeys had seroconverted by the neutralization test in each of groups A, B, and C, and three of five monkeys in group D (one monkey died from cardiac collapse after anesthesia) had seroconverted. Immune enhancement of dengue virus infection is known to occur in humans and monkeys circulating heterologous flavivirus antibodies. In this study, there was no enhancing effect when antibody was mixed with dengue type 2 vaccine virus and injected subcutaneously.

Animals↗