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J C Ruiz

Publications and source records attributed to J C Ruiz.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Prevention of vitamin D deficiency in the child and adolescent. I. Proposal and arguments for use of a decision tree].

A decision-making table, using three questionnaires, is proposed to determine the vitamin D status in children and adolescents. The first questionnaire assesses the vitamin D endogenous synthesis, taking into account the sunlight exposure and the time interval out of the sun. The second questionnaire quantifies the vitamin D dietary intake within three levels: optimal, medium or low. In case of a medium dietary score, a third questionnaire evaluates the daily calcium intake, taking into account the fact that vitamin D metabolism is increased by a low calcium intake (under 400 mg/day). This decision-making table should enable the detection of children and adolescents at risk of vitamin D deficiency and requiring an adapted prophylaxis. Its accuracy will be assessed in prospective surveys.

Adolescent↗
PubMed1999

Growth hormone treatment of short stature and metabolic dysfunction in juvenile chronic arthritis.

Severe growth retardation and profoundly altered body composition are observed in children treated with glucocorticoids for systemic forms of juvenile chronic arthritis. The aim of this study was to assess the effects of 1 year of treatment with growth hormone (GH) on height velocity and body composition, and the potential effects of such treatment on glucose tolerance. Fourteen children receiving steroid therapy for juvenile chronic arthritis were treated with GH, 1.4 IU/kg/week (0.47 mg/kg/week), for 1 year and were then followed up for 1 year after cessation of treatment. Baseline GH secretion and plasma levels of insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) were at the lower limit of normal, but increased with GH treatment. During the year of GH treatment, mean height velocity increased from 1.9 to 5.4 cm/year (p < 0.001), mean lean body mass increased by 12% (p < 0.01) and mean fat mass fell by 20% (p < 0.01) compared with baseline. Decreased glucose tolerance and increased glycosylated haemoglobin levels were also observed. This may have been a result of insulin resistance, as indicated by induced hyperinsulinaemia. Following the 1-year GH treatment period, height velocity fell to pretreatment values, and the height SDS at the end of the second year was lower (p < 0.01) than before treatment. Weight and fat mass increased markedly after cessation of GH treatment. These results suggest that GH may partially counteract the adverse effects of glucocorticoids on growth and metabolism in patients with chronic inflammatory disease. Long-term controlled studies are needed to determine the risks and benefits of GH therapy in such patients.

Adolescent↗
PubMed1998

Ephrin-A1 is expressed at sites of vascular development in the mouse.

B61 (ephrin-A1), a ligand for eph receptor-protein tyrosine kinases, possesses angiogenic and endothelial cell chemoattractant activity. We report the expression profile of ephrin-A1 during mouse embryogenesis (7.25 to 10.5 days post-coitum (dpc)). Ephrin-A1 expression was first detected in the caudal end of the primitive streak and the developing allantois. At mid head fold stage, ephrin-A1 transcripts were observed in the anterior pharyngeal endoderm that underlies the site of the future heart. In 8.0 to 8.5 dpc embryos, ephrin-A1 was expressed in presumptive endocardial cells, the dorsal aorta, and the primary head veins. In 9.5 to 10.5 dpc embryos, ephrin-A1 RNA was detected in intersomitic vessels and the limb bud vasculature. Each site of ephrin-A1 expression corresponded to regions of vasculogenesis and/or angiogenesis.

Animals↗
PubMed1998

Effect of serum phosphate on parathyroid hormone secretion during hemodialysis.

BACKGROUND: Recent studies have demonstrated that a high concentration of phosphate directly stimulates parathyroid hormone (PTH) secretion. High serum levels of phosphate are usually observed in patients with end-stage renal disease. The aim of the present study was to evaluate whether serum phosphate concentration had an acute effect on PTH secretion in hemodialysis patients. The levels of serum phosphate were manipulated during the hemodialysis session by using a phosphate free dialysate or a dialysate with a high content of phosphate. METHODS: Ten stable hemodialysis patients with PTH values above 300 pg/ml were included in the study. A PTH-calcium curve was obtained during both high phosphate and phosphate free hemodialysis. RESULTS: The serum phosphate concentration remained high (2.17 +/- 0.18 mM) throughout the high phosphate hemodialysis and decreased progressively to normal levels (1.02 +/- 0.06 mM) during the phosphate free hemodialysis. The serum PTH levels at maximal inhibition by hypercalcemia (minimal PTH) were greater during the high phosphate than the phosphate free hemodialysis (413 +/- 79 vs. 318 +/- 76 pg/ml, P < 0.003). In all patients the values of minimum PTH were greater during the high phosphorus than the phosphorus free hemodialysis. The values of maximally stimulated PTH during hypocalcemia and the set point of the PTH-calcium curve were similar during the high phosphate and the phosphate free hemodialysis. CONCLUSION: The maintenance of high serum phosphorus levels during hemodialysis prevented, in part, the inhibition of PTH secretion by calcium, which strongly suggests that in hemodialysis patients high serum phosphate contributes directly to the elevation of PTH levels despite normal or high serum calcium concentration.

Adult↗
PubMed1998

Evaluation of dual-energy X-Ray absorptiometry for body-composition assessment in rats.

Recent developments in dual-energy X-ray absorptiometry (DXA) have rendered feasible the determination of whole-body composition in small laboratory animals by directly measuring fat, fat-free and mineral bone masses. Our aim was to evaluate this technique by cross-calibrating the DXA method with the carcass chemical analysis in a heterogeneous population of nondiabetic Wistar and diabetic GK rats (21 animals were used for precision error and reproducibility determinations and 26 were used for accuracy studies). We report that this technique is optimized for weights >200 g. The respective CV for lean mass, fat mass and percentage of fat mass determined in short-term or transversal studies was 1.1 +/- 0.1, 3.0 +/- 1.3 and 3. 1 +/- 0.4% (mean +/- SD) respectively. Further, this technique is valid for rats weighing from 130 to 200 g by using three successive scans. In longitudinal studies, daily calibrations significantly increased the percentage of fat mass CV to 6.6 +/- 3.3%, but it was significantly decreased to 3.0 +/- 2.7% by the use of triplicate scans. The accuracy for DXA was excellent in reference to the chemical extraction technique (r2 = 0.95 for percentage of fat mass, P < 0.0001), using an adjustment factor of 0.75 (limits of agreement between the two methods for percentage of fat mass = -1.7-2.3%). Mimicry of longitudinal changes in body composition with intraperitoneal injections of saline solution demonstrated a satisfactory detection of body component changes (</=2% of error for each final component analyzed, when increasing total lean mass by 11. 8%). We conclude that DXA is appropriate for rat whole-body composition determination, allowing reliable long-term follow-up of individual animals for the first time.

Absorptiometry, Photon↗
PubMed1998

Beneficial effects of one-year growth hormone administration to children with juvenile chronic arthritis on chronic steroid therapy. I. Effects on growth velocity and body composition.

Severe growth retardation and profoundly altered body composition are observed in children with systemic forms of juvenile chronic arthritis receiving glucocorticoids. The purpose of this study was to assess the effects of recombinant human GH (rhGH) on growth velocity (GV) and body composition studied by dual-energy X-ray absorptiometry, during a 1-yr treatment course, together with potential adverse effects on glucose tolerance. Fourteen patients were treated with rhGH (1.4 U/kg per week) for 1 yr and were then studied for a 2nd yr off GH. Baseline GH secretion, GH binding protein (BP), insulin-like growth factor-I (IGF-I), and IGFBP3 levels were at the lower limit of normal. The rhGH treatment increased IGF-I and IGFBP3 plasma levels to above-normal values. All patients showed an increase in GV, and mean GV increased from 1.9-5.4 cm/yr (P < 0.001). Compared with the value on day 0, lean body mass increased by 12.2% (P < 0.01), and the fat mass excess fell by 19.5% (P < 0.01). Decreased glucose tolerance (as determined by oral glucose tolerance test) and increased glycosylated hemoglobin levels were observed during treatment. This effect may be attributed to insulin resistance, as reflected by induced hyperinsulinemia. Eleven children were monitored for 1 yr after the cessation of GH therapy. GV fell to pretreatment values, whereas height in SD score at the end of the 2nd yr was lower (P < 0.01) than before treatment. Weight and fat mass again increased markedly. Although long-term controlled studies are needed to assess the risks and benefits of GH therapy in this setting, our results suggest that rhGH may partially counteract the adverse effects of glucocorticoids on growth and metabolism in patients with chronic inflammatory disease.

Absorptiometry, Photon↗
PubMed1997

Weight gain at the time of menopause.

The menopause is associated with changes in body composition: a decline in bone mineral content, a decrease in collagen synthesis, a loss of lean body mass and an increase in total and abdominal fat mass. Oestrogen deficiency seems to play a role in the menopause-related changes in body composition, but life styles (diet, exercise, smoking habits, alcohol consumption) are also involved. The time course of the decrease in lean mass deserves attention since it could justify specific actions, i.e. exercising or hormonal treatment, early during the perimenopausal period. A decrease in fat-free mass may be responsible for a decrease in energy expenditure favouring weight gain if the calorie intake is not reduced.

Body Constitution↗
PubMed1997

Bone mineral density and metabolism in children with congenital hypothyroidism after prolonged L-thyroxine therapy.

The effect of long-term L-thyroxine (LT4) replacement therapy on bone mineral density and on biochemical markers of bone turnover were studied in children with congenital hypothyroidism (CH). Forty-four children and adolescents (mean age 8.5 +/- 3.5 years) with primary CH who began LT4 replacement therapy within the first month of life were studied. Bone mineral density (BMD) of the lumbar vertebrae and the upper femoral bone was measured by dual energy X-ray absorptiometry. Serum osteocalcin (OC) and bone alkaline phosphatase were measured as markers of bone formation and urinary deoxypyridinoline was taken as a marker of bone resorption. Bone mineral densities of CH children were not different from those in age-matched controls. The biochemical markers of bone turnover were normal except for the serum OC levels which were found to be higher than in controls and positively correlated with the free thyroid hormone levels (for FT4 r = 0.42, p = 0.02). Eight CH children demonstrated low BMD values (below -1 SDS) at -2 +/- 0.7 SDS for the lumbar spine and -1.6 +/- 0.5 SDS for the femoral site. These eight children showed lower mean weight (p < 0.05) and their dietary calcium intake tended to be less (p <0.06) than that seen in the normal BMD group. In conclusion, our results show that LT4 replacement therapy for 8 years is not detrimental to the skeletal mineralization of CH children. As in a healthy population, weight and current intake of calcium seem to be major determinants of bone density. Dietary recommendations, especially when calcium intake is below the recommended dietary allowance, may have to be reconsidered.

Absorptiometry, Photon↗
PubMed1997

Bronchiolitis obliterans and IgA nephropathy. A new cause of pulmonary-renal syndrome.

IgA nephropathy is a common form of glomerulonephritis, classically manifested by asymptomatic hematuria. Although the exact pathophysiologic mechanism is still unknown, renal damage has been related to mesangial deposition of IgA-containing immune complexes. In recent years, some lung diseases have been associated with IgA nephropathy, including pulmonary hemorrhage and sarcoidosis. We report a patient with idiopathic bronchiolitis obliterans who developed a rapidly progressive glomerulonephritis due to IgA deposits. Extensive deposits of IgA were also found in the lungs, thus suggesting a pathogenetic role for IgA in tissue injury at both organ levels. To our knowledge this association has not been previously described in the literature.

Aged↗