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Biomedical subjects

F Rivas

Publications and source records attributed to F Rivas.

At least 91 records · Page 5Linked to original sources
PubMed1980

Deficient cell immunity and mild intermittent hyperaminoacidemia in a patient with the Rubinstein-Taybi Syndrome.

A boy aged 2 years 8 months presenting the Rubinstein-Taybi Syndrome (RTS) and a history of recurrent gastrointestinal and respiratory infections was studied. Partial deficient cell immunity and intermittent hyperaminoacidemia and aminoaciduria were ascertained. These findings were interpreted as evidence of phenotypic and probably genetic heterogeneity of RTS.

Abnormalities, Multiple↗
PubMed1980

Effect of hyperoxia on regional blood flow after coronary occlusion in awake dogs.

The effect of 100% oxygen inhalation on regional transmural myocardial blood flow following 45 s of actue total left circumflex coronary artery occlusion was studied in six awake dogs chronically instrumented with a coronary occluder and catheters in the aorta and left atrium. After inhalation of either room air or 100% oxygen for at least 30 min and following the 45-s occlusion, transmural myocardial blood flow was determined with radioactive microspheres (7--10 micrometers). Each dog underwent two occlusions of the left circumflex coronary artery; one during inhalation of rrom air and the other during 100% oxygen. During room air inhalation, mean regional myocardial blood flow to nonischemic, intermediate, and ischemic regions was 0.92 +/- 0.05, 0.51 +/- 0.08, and 0.10 +/- 0.02 ml . min-1 . g-1, respectively. During 100% oxygen administration, flow was significantly diminished in each region to 0.75 +/- 0.04, 0.41 +/- 0.07, and 0.06 +/- 0.01 ml . min-1 . g-1, respectively. Transmural blood flow to each layer was uniformly reduced in all regions. These data indicate that 100% oxygen further reduces myocardial blood flow to ischemic regions.

Animals↗
PubMed1979

On the deletion 4p16 Wolf-Hirschhorn syndrome.

Two girls (aged 46 and 5 months) and one boy aged 5 months) were studied and found to have the Wolf-Hirschhorn syndrome. Chromosomal complement in all three cases implicated the deletion of the 4p16 band ; in two of them an extra segment of autosomal material was found to be translocated to 4p. Parents' karyotypes were normal. It is concluded that the expression of the 4p16 monosomy is stronger than that of some simultaneous partial trisomies.

Abnormalities, Multiple↗
PubMed1979

Hemolytic anemia caused by glucose-6-phosphate dehydrogenase deficiency.

Results are reported concerning quantitation of glucose -6- phosphate dehydrogenase (G6PD) enzyme activity where in one of the members of a family a clinical diagnosis of acute hemolytic anemia due to G6PD deficiency had been established. In the propositus, G6PD levels were found to be less than 10 per cent thus confirming diagnosis; the same enzymatic deficiency was identified in one of the siblings without a history of hematologic pathology and in a maternal cousin with a history of neonatal jaundice as well as two obliged carriers. Electrophoretical enzyme phenotype was similar to A variant in three affected males. Advantages of prevention and medical care possible with early diagnosis of G6PD deficiency are discussed.

Adolescent↗
PubMed1976

Evaluation of 99mtechnetium stannous pyrophosphate as an imaging agent in acute myocardial infarction.

Serial 99mTc pyrophosphate scintigrams were obtained 7 hr to 15 days after experimental acute myocardial infarction produced by permanent or transient coronary occlusion. Scintigrams were interpreted visually and the increased radioactivity in the precordial image was quantitated and compared to extent of infarction found histologically. Results of these studies indicate: 1) 99mTc pyrophosphate imaging is an extremely sensitive for detection of acute myocardial infarction, i.e., infarction in excess of 1% of the left ventricular mass was detected. 2) Early detection of acute infarction is a function of blood flow since 7 hr after infarction scans were negative after permanent occlusion but were strongly positive after transient occlusion. 3) Radioactivity in the precordial image was inversely related to extent of infarction after permanent occlusion and directly related to extent of infarction after transient occlusion. 4) 99mTc pyrophosphate localized in areas with significant histologic infarction but the distribution of radioactivity was not proportional to extent of infarction.

Animals↗
PubMed1976

Relationship between blood flow to ischemic regions and extent of myocardial infarction. Serial measurement of blood flow to ischemic regions in dogs.

This study was designed to measure early sequential changes in blood flow to ischemic regions after acute coronary occlusion and to determine the relationship between blood flow and the extent of subsequent myocardial infarction. Initial studies were carried out on five dogs which verified using radioisotope-labeled microspheres, 7-10 mum in diameter, to measure changes in blood flow in small myocardial regions after acute coronary artery occlusions. Studies then were carried out on 11 awake dogs chronically prepared with dwelling catheters in the aorta and left atrium and occluders on the left circumflex coronary artery. Microspheres were injected via the left atrial catheter 45 seconds and 2, 6, and 24 hours after complete circumflex coronary occlusion. Six days later myocardial blood flow and the extent of histological infarction were determined for multiple samples from four transmural layers of the entire ischemic zone. Average blood flow to the circumflex region was 0.25 +/- 0.03 (SE), 0.39 +/- 0.05, and 0.53 +/- 0.07 ml/min per g at 45 seconds, and 2, 6, and 24 hours, respectively. When samples from each transmuarl layer were grouped according to increasing ranges of blood flow, the extent of infarction in each layer was inversely related to blood flow. When samples in the same range of blood flow were compared, the extent of infarction in endocardial samples exceeded that in epicardial samples. These data indicate that the relationship between a given measurement of regional blood flow after acute coronary occlusion and the extent of subsequent myocardial infarction varies in different transmural layers and is a function of the time after occlusion that blood flow is measured.

Animals↗
PubMed1976

Local effects of acute cellular injury on regional myocardial blood flow.

This study was designed to examine local effects of acute cellular injury on regional myocardial blood flow. Studies were carried out in awake dogs chronically prepared with indwelling catheters in the aorta and left atrium and an occluder on the left circumflex coronary artery. Regional myocardial blood flow was measured by using 7-10-mum radioisotope-labeled microspheres after reestablishing inflow to a region subjected to a 2-h complete coronary occlusion. Microspheres were injected 15 s, 15 min, 4 h, and 3 days after reperfusion to assess effects of cell injury at varying intervals after reperfusion. Effects of acute cellular injury on blood flow were assessed by determining the relationship between regional blood flow and the extent of subsequent cellular necrosis measured in multiple tissue samples, weight 1-2 g, from the entire ischemic zone. The extent of cellular necrosis was determined from histological sections of each tissue sample. Prolonged ischemia effected local tissue responses which altered perfusion as a function of the interval after reperfusion and the subsequent extent of myocardial necrosis. Although the net response in each region immediately after reperfusion was vasodilation, the hyperemia in regions which subsequently suffered cellular necrosis was attenuated in direct proportion to the extent of subsequent infarction. Blood flow to acutely injured regions remained equal to, or in excess of, flow to nonischemic regions 15 min after reperfusion, but at 4 h and 3 days after reperfusion, flow was significantly decreased in regions with greater than 50% infarction. Thus, these data indicate that prolonged ischemia initiates tissue responses which progressively reduce myocardial perfusion after reperfusion. These effects on tissue perfusion may result from normal responses to irreversible injury and (or) abnormal responses to reversible and thus, potentially alterable, ischemic injury.

Animals↗
PubMedDate not supplied

inv(9)(p24q13) in three sterile brothers.

Only nine non-polymorphic constitutional pericentric inversions of chromosome 9 have been described. We report on a familial inv(9)(p24q13) associated with sterility in three brothers. The mother's chromosomes were normal in blood lymphocytes (n=130); the father was already deceased and his karyotype unknown. However, the presence of any of the maternal chromosomes 9 (as assessed by C-banding) in her carrier children is inconsistent with the assumption of maternal mosaicism. Two single sisters were also carriers. The same rearranged chromosome 9 in the three sterile brothers can hardly be regarded as a fortuitous association, especially when the breakpoints are almost identical to those of the sole inversion previously found in an azoospermic male. If their father was a carrier, the observed sterility may be the result of 'chromosome anticipation', a phenomenon already invoked for certain familial chromosomal rearrangements.

Adult↗
PubMedDate not supplied

The C677T polymorphism of the methylenetetrahydrofolate reductase gene in Mexican mestizo neural-tube defect parents, control mestizo and native populations.

The C677T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene, associated with the thermolabile form of the enzyme, has reportedly been found to be increased in neural-tube defects (NTD), though this association is still unclear. A group of 107 mestizo parents of NTD children and five control populations: 101 mestizo (M), 50 Huichol (H), 38 Tarahumara (T), 21 Purepecha (P) and 20 Caucasian (C) individuals were typed for the MTHFR C677T variant by the PCR/RFLP (HinfI) method. Genotype frequencies were in agreement with the Hardy-Weinberg expectations in all six populations. Allele frequency (%) of the C677T variant was 45 in NTD, 44 in M, 56 in H, 36 in T, 57 in P, 35 in C. Pairwise inter-population comparisons of allele frequency disclosed a very similar distribution between NTD and M groups (exact test, P=0.92). Among controls, differences between M and individual native groups were NS (0.06<P<0.21), as it was between M and C (P=0.29). A high frequency of the variant was found in H (56%) and P (57%). A similar allele frequency in groups M and NTD does not support a causal relationship between NTD and parental MTHFR C677T genotypes. Thus, the C677T variant cannot be regarded as a major genetic risk factor for NTD in Mexican mestizo parents. Otherwise, C677T in Mexico is very frequent, especially in Huichol and Purepecha natives, as compared with other groups world wide.

DNA↗
PubMedDate not supplied

Alpha-1,4-glucosidase activity and the presence of germinal epithelium cells in the semen for differential diagnosis of obstructive and nonobstructive azoospermia.

Among azoospermics, the activity of seminal alpha-glucosidase (alpha G) is low in obstruction (OBS) cases, but there is no agreement regarding its value in others. With the hypothesis that a more marked decrease in alpha G activity occurs in OBS than in spermatogenesis arrest (SA), the enzyme was measured in the following groups: (1) vasectomized males (n = 15), (2) azoospermics with OBS (n = 7), (3) azoospermics with SA (n = 11), and (4) fertile males (n = 15). Patients within groups 2 and 3 had a testicular volume > or = 15 mL, no clinical evidence of abnormal epididymis, normal serum gonadotropins, and histological diagnosis. alpha G activities (mU/g protein, means +/- SD) by group were (1) 131 +/- 60, (2) 312 +/- 186, (3) 728 +/- 303, and (4) 1176 +/- 374. All between-group differences were significant (t test, p < .01), except for groups 1 vs. 2 comparison (.05 > p > .01). These results support the notion that SA is associated with a decrease in alpha G that is less marked that seen in OBS. The search for germinal epithelium cells in semen also allows discrimination between these two azoospermic groups.

Clinical Enzyme Tests↗
PubMedDate not supplied

Ultrastructure of 26 cases of Ki-1 lymphomas: morphoimmunologic correlation.

Twenty-six cases of high-grade lymphomas with activation markers (CD30) classified and immunophenotyped according to the Kiel classification were studied to determine their fine structural features. Transmission electron microscopy showed in 17 cases anaplastic nuclear and cytoplasmic changes identical to those observed in Hodgkin's disease, it being impossible to determine by the morphology a B, T, or null nature. Four high-grade B-centroblastic and immunoblastic cases and five T-pleomorphic cases showed nuclear changes and cytoplasmic differentiation that suggested a T or B nature. An immunogold-labeling technique showed CD30-positive particles primarily in the Golgi complex and occasionally in the cell membrane.

Antigens, Differentiation↗
PubMedDate not supplied

Lennert's lymphoma with giant multivesicular lysosomal bodies optically visible.

A case of a 43-year-old male patient with lymphoepithelioid lymphoma is discussed. During the 10-year follow-up of this patient, different biopsy specimens were obtained. Immunohistochemical studies with a complete paraffin panel determined a T-cell nature of the specimens. Electron microscopy showed a peculiar finding in the cytoplasms of the tumoral cells that correlated with optical inclusions observed in optical imprints; these imprints corresponded to lysosomic multivesicular bodies, whose significance is discussed.

Adult↗
PubMedDate not supplied

[Cryptococcus neoformans isolation from the soil in Panama].

Reports of Cryptococcus neoformans isolations from patients in Panama have appeared since 1978, but to our knowledge, thIs is the first report of isolation of this organism from soil samples in the Republic. Of 25 soil samples analyzed, two (25%) yielded the organism on birdseed agar medium. Canavanine-glycine-bromthymol blue medium served to identify the isolates as belonging to C. neorformans var neoformans, and not C. Neoformans var. gattii. Initially, isolates did not have capsules, but upon passage through newborn mice, wide capsules developed. This finding has important public health implications, since non-encapsulated environmental organisms, once in the host, can develop capsules, which significantly contribute to virulence.

Cryptococcus neoformans↗
PubMedDate not supplied

[Lack of predictive power of cerebrospinal fluid calcitonin and serotonin concentrations for the intensity of postoperative pain and the duration of analgesia after subarachnoid morphine administration].

Based on the important relationship of calcitonin and serotonin with narcotic drugs at the level of the central nervous system and with the modulating mechanisms of pain sensation, we have studied whether central baseline levels of these modulators possess a predictive value for the assessment of the intensity and duration of narcotic spinal analgesia. Therefore, intradural levels of calcitonin an serotonin were measured in 18 patients who underwent and infraumbilical laparotomy with intradural anesthesia with bupivacaine associated with 0.5 mg of morphine. There was no statistically significant correlation between the levels of calcitonin and serotonin with the age, weight, height, sex, values of analogic visual scale 2, 4, 6, 12 and 24 hours after lumbar punction, and duration of the analgesia. Even though a correlation exists in experimental models, our results indicate that baseline values of modulators calcitonin and serotonin lack of predictive value for the assessment of the degree and duration of narcotic spinal analgesia.

Adult↗