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Biomedical subjects

J C Ruiz

Publications and source records attributed to J C Ruiz.

125 records · Page 7Linked to original sources

Plasma bone Gla-protein: assessment of its clinical value as an index of bone formation in hemodialyzed patients.

Plasma bone-Gla protein was measured in 27 non-selected patients on chronic hemodialysis or hemofiltration with no overt radiological bone disease. Individual values ranged from normal to 10-times the upper limit of the normal range. Plasma bone-Gla protein correlated with the histomorphometric parameters of bone turnover and bone formation and with plasma parathyroïd hormone and alkaline phosphatase. When patients were classified according to their Bone Formation Rate, plasma bone-Gla-protein allowed a better distinction between high and low bone formation rates than did alkaline phosphatase or plasma parathyroïd hormone.

Adult↗

Escherichia coli aspartate transcarbamylase: a novel marker for studies of gene amplification and expression in mammalian cells.

Eucaryotic expression vectors containing the Escherichia coli pyrB gene (pyrB encodes the catalytic subunit of aspartate transcarbamylase [ATCase]) and the Tn5 phosphotransferase gene (G418 resistance module) were transfected into a mutant Chinese hamster ovary cell line possessing a CAD multifunctional protein lacking ATCase activity. G418-resistant transformants were isolated and analyzed for ATCase activity, the ability to complement the CAD ATCase defect, and the ability to resist high concentrations of the ATCase inhibitor N-(phosphonacetyl)-L-aspartate (PALA) by amplifying the donated pyrB gene sequences. We report that bacterial ATCase is expressed in these lines, that it complements the CAD ATCase defect in trans, and that its amplification engenders PALA resistance. In addition, we derived rapid and sensitive assay conditions which enable the determination of bacterial ATCase enzyme activity in the presence of mammalian ATCase.

Animals↗

Assessment of divided renal function by renography. Validation in patients with separate urine collections from each kidney.

Divided renal function was measured by 99mTc-DTPA renography using a gamma camera and a computer-assisted program. In 14 patients with permanent bilateral ureterostomies (7) or temporary ureteric catheterization (7), split renal function was calculated by analysis of the initial phase of the kidney activity-time curve and measured simultaneously by conventional clearance techniques. A high correlation was found between individual clearances measured by computation and by the conventional procedure. The correlation coefficient between the results obtained by the two techniques was 0.94 (P less than 0.001). A high correlation was also shown to exist between the computed clearance and the renal uptake of mercury after administration of 197HgCl. It is concluded that 99mTc-DTPA is particularly useful for the measurement of divided renal function without the need for urine collection.

Humans↗

Effect of acute ethanol loading on parathyroid gland secretion in the rat.

Acute ethanol loading in the rat induces hypocalcemia and hypermagnesemia. In addition, hypocalcemia is not corrected by exogenous PTH. In the rat the mechanism of these changes was investigated by measuring plasma immunoreactive parathyroid hormone (PTH). PTH was also measured in culture medium in which parathyroid glands were incubated. The addition of ethanol to test tubes did not interfere with PTH measurement. Absolute ethyl alcohol diluted to 50% with distilled water was administered via an intragastric tube. It failed to induce an increase in plasma immunoreactive PTH level. Similarly, it prevented an increase in plasma PTH after disodium EDTA injection. Thus in the presence of ethyl alcohol plasma PTH failed to increase in spite of a significant decrease of plasma calcium. In vitro studies showed that the decrease of calcium concentration of the medium from 1.50 to 0.75 mmol/l was associated with a 3 to 5 times increase in PTH secretion rate. This increase was suppressed when ethanol was added to the culture medium. In conclusion, ethanol loading via gastric tubing induced: 1) decrease in plasma calcium; 2) suppression of immunoreactive PTH secretion in the presence of hypocalcemia. It is postulated that the acute hypocalcemic effect of ethanol loading is mediated by a dual effect at the level of the bone and the parathyroid gland.

Animals↗

[Anti-HBs antibody. A new immunoenzymatic detection. Preliminary results (author's transl)].

The detection of anti-HBs antibody has been carried out using a new technique where a system for the detection of HBs antigen in the solid phase is adopted to demonstrate the presence of anti HBs antibody by inhibition of the immunoenzymatic reaction. The sensitivity of the method has been compared: with that of passive haemagglutination and with that of radioimmunoassay in liquid phase, for human serum obtained from 10 chronic antibody carriers and also serum from 1 rabbit, with that of solid phase radioimmunoassay for 91 positives serums. The method appears: in the range of sensitivity of passive haemagglutination and radioimmunoassay in the liquid phase, less sensitive than that of solid phase radioimmunoassay, far superior to that of electrosyneresis.

Animals↗

[Effect of recipient age on the clinical course of renal transplantation].

Since the immune response in older recipients has been described as weaker they may have a lower risk of rejection of a transplanted organ. Therefore a less aggressive immunosuppressive regimen should be the best option. The aim of our study was to evaluate the incidence and severity of acute rejection (AR) episodes on graft survival of older patients (> or = 60 years) and to compare them with the younger ones (< 60 years). A total of 439 kidney transplants were performed between 1/94 and 12/99 at our Transplant Unit. Clinical and immunological data, incidence and severity of AR and cause of graft loss were recorded. Patients were divided into two groups, according to age at transplantation [A (< 60, n = 342/77.9%) and B (> or = 60, n = 97/22.1%)]. The percentage of aging recipients and mean age of both donors and recipients increased through the period of study. Although the incidence of acute tubular necrosis was higher in the older group (31% vs 22.8%, pNS), the incidence of AR was also similar (31.6% vs 29.8%, pNS). The number of AR episodes per patient was 0.44 and 0.41 respectively. The incidence of AR was higher in those patients who had ATN (50% vs 19.6%), p < 0.01). The severity of AR was: Banff grade I: A (40.3%)/B (45.7%) pNS; grade II: A (44.1%)/B (48.5%) pNS; grade III: A (15.6%)/B (5.8%) pNS. One-year patient survival was 96%/91% (p < 0.001) and graft survival was 81%/78% (pNS) respectively. The age of recipient does not seem to have a significant influence on the incidence and severity of AR or on graft survival. So immunosuppression should be individualized for each patient.

Acute Disease↗

[Variability of bone response to hormone replacement therapy].

Bone response to hormone replacement therapy (HRT) was assessed in a retrospective longitudinal study. 115 women started on HRT for the first time and 252 controls underwent initial densitometric evaluation (spine and femur) and a second evaluation on average 29 months later. Patients were classified as post-menopausal or perimenopausal according to whether they had had more or less than 6 months amenorrhea. Oral or non-oral 17-beta estradiol was used at the dose generally accepted to be skeletally protective. In the post-menopausal group, prescription of HRT was followed by spinal and femoral bone gain (+ 2.85% and + 1.06% per year respectively). There was no bone gain with HRT in the peri-menopausal women, but the stability seen contrasted greatly with the very marked bone loss found in controls (spine - 3.09% per year and femur - 1.78% per year). Lumbar densitometric variations were correlated, at least in the post-menopausal group, with those in the femur, but the amplitude of femoral variations was half that of the spine. Body mass index (BMI) was not found to be a predictive factor of bone response to HRT in this group, but the time since the menopause and initial densitometric results were. For the spine, the % of subjects losing their bone mass in response to the start of HRT, nil in the post-menopausal group, was 16% in peri-menopausal women. The % of good responders increased from 8% peri-menopausally to more than 59% 2 years after the menopause. The response in the femur appeared to be very different, with 20% good responders and a % of stable subjects similar to that of the control group. Femoral variations and the existence regarding the spine of a group showing no or only a poor response to HRT would be in favor of densitometric monitoring when initial bone mass is low.

Absorptiometry, Photon↗