Biomedical subjects
M C Rivas
Publications and source records attributed to M C Rivas.
Osteoporosis after cardiac transplantation.
PURPOSE: The purpose of this study was to determine the prevalence of osteopenia and fractures and to describe the biochemical indices of mineral metabolism in patients who have undergone cardiac transplantation. PATIENTS AND METHODS: Forty adult patients who had received a cardiac transplant between 1982 and 1990 and who were receiving immunosuppressive therapy with prednisone and cyclosporine A were studied. Bone densitometric measurements by dual-energy x-ray absorptiometry of the lumbar spine and femoral neck and radiographs of the thoracic and lumbar spine were obtained for all patients. Routine serum and urine biochemical values as well as more specialized biochemical analyses (intact parathyroid hormone, metabolites of vitamin D, and osteocalcin) were obtained. RESULTS: Osteopenia was present in 28% of the patients at the lumbar spine and 20% of the patients at the femoral neck. Vertebral fractures were present in 35% of patients. In contrast to other patients receiving glucocorticoids, serum osteocalcin, a marker of bone formation, was elevated in 60% of patients. CONCLUSIONS: Osteopenia and vertebral fractures are common in patients after cardiac transplantation. The presence of elevated osteocalcin levels suggests that the pathogenesis of the osteoporosis in these patients differs from that of glucocorticoid-induced osteoporosis.
[Post-therapeutic evolution and prognostic factors of intestinal lymphomas, Retrospective analysis of 42 cases].
PURPOSE: To evaluate in retrospect the response to therapy and long-term evolution of a series of primitive intestinal lymphomas. PATIENTS AND METHODS: The series was comprised of 42 patients diagnosed in our hospital during 1960-1962. The mean age was 34.5 years (range, 3-73), the M/F ratio was 21/21, and the histopathology distributes as follows: high grade (HG), 24 cases, low grade (LG), 12 cases, and mixed (LG/HG), 6 cases. B/T immunophenotype: 40/2. Staging: IE1,29 cases, IIE2-IV, 11 cases. The treatment applied in the series was classified in various types: ample surgical resection (aSR), 21 cases; partial surgical resection (pSR), 9 cases; abdominal radiation therapy (RT), 7 cases; monochemotherapy (MCT), 7 cases, and polychemotherapy (PCT), 28 cases. The correlation of clinicobiological variables with immediate response to treatment was evaluated by means of the chi square test, and the acturial post-therapeutic survival curves in accordance to the life tables, differences being calculated by the log rank test. RESULTS: Small intestine was the commonest site of involvement, 31 cases; ileocecal region, 7 cases; colon, 2 cases, and colon plus small intestine, 2 cases. Regardless of therapy type, complete remission (CR) was attained in 20 patients (47.5%), partial remission in 5; 11 cases were unresponsive (26.5%) and early death occurred in 6 instances (14.2%). The acturial post-therapeutic survival offered an 8-year expectancy of 47%. The correlation between immediate complete response and 16 clinico-biologic variables showed favourable significance for tumoral proliferation index (i.e., Pc10-positive cells < 15%) and for therapeutic regimens including PCT+aSR. On the other hand, the necessity of emergency surgery for diagnosis was a poor-risk factor. The correlation between a post-therapeutic survival and 19 other variables showed the following as favorable data: female sex, tumour proliferative index (i.e., Pc10-positive cells < 15%), the use of PCT+aSR, and attaining CR. Poor-risk factors were the need of emergency surgery, multicentric lymphomatous involvement and serum LDH rates 350 UI/L. Although immediate response (CR) and long-term results (survival) were better in the patients with favourable histology (LG+LG/HG) and in those with loco-regional disease (stages IE-IE1), the differences had no statistical significance, possibly due to the low number of cases. CONCLUSIONS: 1) Even though these findings should be carefully evaluated, dut to lack of homogeneity of the series and the fact of being a retrospective study, the rate of CR in this series (47.5%) is similar to that of current studies. 2) Female sex, type of therapy, multifocal involvement, the need of emergency surgery and high LDH levels have significant value in univariate analyses.
Gastric B-cell mucosa associated lymphoid tissue lymphoma: a clinicopathological study in 56 patients.
Clinico-pathological features of 56 patients with primary gastric lymphoma were evaluated retrospectively. All cases were regraded according to a classification of Isaacson et al into high grade and low grade B-cell mucosa associated lymphoid tissue lymphoma. A third group of mixed grade was recognised in 11 patients with low grade who also had occasional areas of high grade. Low grade and mixed grade patients had a 100% actuarial survival at 156 months, which was significantly better (p < 0.01) than that of 52% for patients with high grade disease. Different treatment methods--surgery, chemotherapy, or a combination of both--did not significantly affect survival. Low grade tumours occurred mainly in men with a history of several years, and who presented with non-specific gastric symptoms without remarkable exploratory or laboratory findings: most patients were in stage IE-IIE and achieved remission and cure. High grade can have a shorter history, systemic symptoms, abnormal exploratory and laboratory findings, gastric tumour masses, stage IV disease, and a worse outcome. The only significant prognostic factors for survival were the type of lymphoma and stage IV disease. These findings support the Isaacson classification system which separates two extreme groups of gastric lymphomas with different morphology, behaviour, and outcome. The presence of limited areas of high grade in a specimen showing low grade does not change the outcome but suggests that primary gastric lymphoma forms a continuum between these extreme types.
Pharmacokinetics of vancomycin in patients undergoing hemodialysis with polyacrylonitrile.
The pharmacokinetics of vancomycin in patients undergoing dialysis with cuprophane membranes are well known, however little has been reported of the use of polyacrylonitrile membranes in dialysis. We studied, in a crossover design, eight dialysis patients (7 men, 1 woman) aged 30 to 66 years who prospectively received 1 gram of vancomycin i.v. before first dialysis and were subsequently hemodialyzed with cuprophane every second day for a total of three times. A month later trial was repeated using polyacrylonitrile. A mono-compartment model was used to calculated pharmacokinetic parameters. Mean +/- standard deviation of vancomycin clearance varied from 5.2 +/- 2.1 ml/min in the interdialysis period to 9.7 +/- 2.7 ml/min during dialysis with cuprophane and to 58.4 +/- 15.6 ml/min during dialysis with polyacrylonitrile (p less than 0.001). Vancomycin half-life varied from 71.5 +/- 23.0 to 35.9 +/- 9.8 and to 6.1 +/- 1.4 hours, respectively (p less than 0.001). Fractional removal of vancomycin increased from 4% using the cuprophane dialyzer to 34% using the polyacrylonitrile dialyzer (p less than 0.001). Serum vancomycin levels at 100 and 168 hours were higher with cuprophane than with polyacrylonitrile (7.0 +/- 2.2 vs 3.9 +/- 1.2 micrograms/ml) (p less than 0.001). Moreover, the mean levels at 100 hours were suboptimal on polyacrylonitrile. Approximately 208 +/- 53 mg of vancomycin were removed during one polyacrylonitrile dialysis. Thus, those patients who undergo dialysis with polyacrylonitrile and are treated with vancomycin may need supplementary doses post dialysis or to lessen dosage intervals than those traditionally used for dialysis patients since clearance of the drug is significantly higher than with cuprophane dialyzers. Continuous monitoring of vancomycin levels is also recommended.
Characterization of circulating idiotypes containing immune complexes and their presence in the glomerular mesangium in patients with IgA nephropathy.
The possible pathogenic role for idiotype-anti-idiotype interactions in kidney diseases has recently been suggested. Since patients with IgA nephropathy often present antibodies against alimentary antigens, like bovine serum albumin (BSA), we isolated an idiotypic antibody with BSA specificity from one of these patients. By means of a specific anti-idiotypic antibody raised in rabbits, we have studied the participation of these idiotypes in circulating and renal deposited immune complexes (IC) in patients with IgA nephropathy. On indirect immunofluorescence, the presence of cross-reactive idiotypes was detected in the glomeruli of 12 out of 42 (28%) patients with IgA nephropathy, but in none of 15 membranous or mesangiocapillary nephritis examined. The staining was located within mesangial and paramesangial areas, with a similar, but less intensive, pattern distribution than IgA. Previous adsorption of rabbit anti-idiotype antibodies on an idiotype-Sepharose column completely abolished that staining. A close relationship was found between the presence of cross-reactive idiotypes on mesangial immunoglobulins and the existence of increased levels of serum idiotypes and idiotype-containing IC. Serum analytical ultracentrifugation showed that circulating IC containing idiotypes have chiefly a large (greater than 19 S) and intermediate (13 S-19 S) size, while those containing anti-BSA antibodies were only between 7 S-13 S fractions, or absent. Our results suggest that in patients with IgA nephropathy, shared idiotypes participate in the formation of circulating and renal deposited IC. It is possible that the apposition of free anti-idiotype to idiotype already bound to glomeruli, and vice versa, could contribute to increasing the amount and size of mesangial immune deposits, and, therefore, facilitate or perpetuate tissue injury.
[Fever in peaks and painful tumor in a 24-year-old woman].
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[A young female with multiple, painful osteosclerotic lesions, developing over a 3-year period].
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[Cytological and anatomo-pathological study of the bone marrow in non-Hodgkin's lymphomas evaluated according to the Kiel classification].
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[Human infection by Yersinia enterocolitica and pseudotuberculosis in Spain. Analysis of 80 recent cases].
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[Trycholeukemia].
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[Angioimmunoblastic lymphadenopathy with biclonal paraproteinemia].
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Intranuclear mitochondriae in Hodgkin's disease.
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