Decreased bone mineral density and bone formation markers shortly after diagnosis of clinical type 1 diabetes mellitus.

We recently demonstrated that children with type 1 diabetes mellitus (DM) have decreased lumbar spine bone mineral density (BMD) as early as four years after clinical diagnosis of the disease. In order to determine whether osteopenia is already present in patients very early on after diagnosis of clinical DM, we evaluated the bone mineral status of a group of newly diagnosed children (5.8 +/- 1.5 mo after diagnosis). We studied 23 prepubertal children (7 M, 16 F) with a mean chronological age of 9.5 +/- 2.2 yr and a mean glycosylated hemoglobin of 8.9 +/- 2.4%. Lumbar spine and femoral neck BMD were measured by dual X-ray absorptiometry, while bone turnover was assessed by the determination of the serum concentration of the carboxy-terminal propeptide of type I collagen (PICP) and the carboxy-terminal cross-linked telopeptide of type I collagen (N-telopeptide). Results were compared to those of age, height, and pubertal status matched controls. Lumbar spine BMD Z-scores were decreased in patients compared to controls (Z-scores of -0.89 +/- 1.2, with 10 of 22 patients showing values >1 SD below the mean). When lumbar spine Z-scores were analyzed in those patients with <3 months or > or =3 months since diagnosis of DM a significant difference was noticed between groups (-0.648 +/- 1.12 vs -1.267 +/- 1.17; p <0.02). No significant differences were noted in femoral neck BMD and total BMD between groups. Serum PICP levels were decreased when compared to controls (233.6 +/- 39.3 vs 375.9 +/- 50.7 microg/l; p <0.002), while serum N-telopeptide concentrations, although increased, were not significantly different (9.3 +/- 1.3 vs 5.7 +/- 1.5 microg/l). In summary, early on after the diagnosis of type 1 DM, children present with decreased lumbar spine BMD and decreased bone formation markers.

Role of persistent amenorrhea in bone mineral metabolism of young hemodialyzed women.

BACKGROUND: Chronic renal failure in women is frequently associated with endocrine disturbances leading to menstrual disorders. However, most studies on renal osteodystrophy have not taken into account the possible role of these hormonal disturbances on the pathogenesis of bone alterations seen in these patients. In the present study, we evaluated bone mineral metabolism in a group of young hemodialyzed women with persistent amenorrhea and compared them with similar women with regular menstruation. METHODS: We studied 74 women who were further subdivided into 43 women with regular menstrual periods and 31 women with persistent amenorrhea, defined as the absence of menstrual bleeding for more than six months. In all patients, we performed a bone mineral density (BMD) analysis and simultaneously evaluated different biochemical parameters, intact parathyroid hormone (iPTH), sexual hormone determinations that included total estradiol, follicle-stimulating (FSH), and luteinizing hormone and markers of bone resorption such as the procollagen type 1 cross-linked carboxy-terminal telopeptide (ICTP). RESULTS: Serum calcium, phosphorus, and iPTH were similar in both groups. Serum alkaline phosphatase was higher in amenorrheic women. Although the total serum estradiol concentration was normal in the amenorrheic women when compared with nonuremic women, the values were significantly lower than those in regularly menstruating women. Serum FSH and ICTP values were significantly higher in the amenorrheic women. Trabecular BMD in the lumbar spine was also significantly lower in the amenorrheic women compared with regularly menstruating dialysis patients. Lumbar spine BMD and total estradiol levels correlated significantly in the amenorrheic group. CONCLUSIONS: These studies show that persistent amenorrheic young women on dialysis have lower trabecular BMD and evidence of increased bone resorption when compared with normal menstruating women on dialysis. The possible impact of these results in the natural history of the uremic osteodystrophy remains to be determined.

Bone disease in patients with long-term renal transplantation and normal renal function.

Renal osteodystrophy may persist during the early years after renal transplantation. However, information on bone status after a successful long-term renal transplantation is limited. We examined biochemical parameters, bone mineral density (BMD), and bone histomorphometry in 25 asymptomatic men with normal renal function after 7.5 +/- 5.7 years of a renal transplantation. Serum calcium, phosphorus, alkaline phosphatase, and 1,25(OH)(2)D(3) levels and urinary calcium level and cyclic andenosine monophosphate excretion were within normal range in all patients. Serum intact parathyroid hormone (PTH) level was elevated in 11 subjects (133.6 +/- 78 pg/mL) and normal in the other 14 subjects (47.9 +/- 13.6 pg/mL). Mean BMD at the lumbar spine and femoral neck was low in the entire group. However, it progressively increased as time after transplantation increased, approaching normal values after 10 years. Bone histomorphometric analysis showed bone resorption, osteoid volume, and osteoid surface greater than normal range in the majority of patients. Bone formation rate and mineralization surface were low, and mineralization time was delayed in most patients. These lesions were more severe in patients after 3 to 4 years of transplantation but improved with time and approached normal values after a period of 10 years. PTH values did not correlate with bone histological characteristics or BMD. These results show that the bone alterations observed after long-term renal transplantation consist of a mixed bone disease in which features of high bone turnover coexist with altered bone formation and delayed mineralization. These findings may result from the combined effect of preexisting bone disease and immunosuppressive therapy.

Decreased bone mass despite long-term estrogen replacement therapy in young women with Turner's syndrome and previously normal bone density.

OBJECTIVE: To determine whether young women with Turner's syndrome who had normal bone mineral density (BMD) before the induction of puberty maintain normal BMD in young adulthood. DESIGN: Controlled clinical study. SETTING: A private hospital clinical research setting. PATIENTS: Young women with Turner's syndrome in Tanner stage V of puberty with previously normal BMD. INTERVENTIONS: Oral conjugated estrogens and progesterone acetate were administered continuously for a mean (+/-SD) of 4.1+/-1.0 years. Bone mineral densities and blood samples were evaluated. MAIN OUTCOME MEASURE(S): The BMD of the lumbar spine and the femoral neck was determined during young adulthood. The change in BMD over the previous 6 years also was evaluated. Serum concentrations of the carboxy-terminal propeptide of type 1 collagen and of the carboxy-terminal cross-linked telopeptide of type 1 collagen were measured. RESULT(S): The BMD of the lumbar spine was reduced significantly in our patients. There was no change in the BMD of the femoral neck or lumbar spine over a period of 6.1 years. Concentrations of the carboxy-terminal propeptide of type 1 collagen were decreased, whereas concentrations of the carboxy-terminal cross-linked telopeptide of type 1 collagen were increased. CONCLUSION(S): Young women with Turner's syndrome do not attain normal peak bone mass even when estrogen replacement therapy is begun in adolescence. Their low BMD seems to be due to decreased bone formation and increased bone resorption.

Latin American nephrology: scientific production and impact of the publications.

BACKGROUND: During the last two decades, there has been a significant change in the origin and impact of the world's biomedical scientific production, particularly in countries in which the investment in research accounts for an important portion of the gross national product (GNP). However, in less developed countries, budget restrictions and the lack of policies toward research may determine a limited growth of the scientific production. METHODS: We examined the number and impact of peer-reviewed publications from Latin America included in the Institute of Scientific Information (ISI) and MEDLINE databases. In addition, we analyzed the number of abstracts submitted to the congresses of the International Society of Nephrology (ISN), American Society of Nephrology (ASN), and Latin American Society of Nephrology and Hypertension (SLANH). RESULTS: The number of peer-reviewed publications in nephrology from authors in Latin America during the last 20 years represented less than 1% of the world's total. Only 13 out of the 22 Latin American countries accounted for these publications. The citation impact (3.52) was below the world average (7.82). However, this index showed a tendency towards growth in the five most productive countries. Likewise, the number of abstracts submitted to international meetings of nephrology by authors in Latin American countries has shown a steady growth in the recent years, but remains proportionately low compared with the rest of the world. CONCLUSIONS: This study indicates that although efforts toward improving the quantity and quality of research in Latin America have been made, the final results are less than other regions in the world. Possible factors responsible for the low performance include a failure in academic motivation and lack of pressure for publication, as well as limited research funding. Therefore, important efforts from local and international nephrological communities are needed to boost research in Latin America.

Decreased trabecular bone mineral density in children with idiopathic short stature: normalization of bone density and increased bone turnover after 1 year of growth hormone treatment.

Patients with growth hormone (GH) deficiency have impaired bone mineral metabolism; treatment with GH leads to an improvement in their bone mineral density (BMD). The effect of GH on the BMD of children with idiopathic short stature is unknown. We studied 14 short, slowly growing, otherwise healthy, prepubertal children without GH deficiency (7 girls and 7 boys) with a chronological age of 10.9 +/- 1.4 years, bone age of 8.8 +/- 1.5 years, and height of 127.8 +/- 8.5 cm (height SD score of -2.2 +/- 0.5). Growth velocity increased from 3.9 +/- 1.1 cm/y to 8.0 +/- 1.9 cm/y, and height SD score improved from -2.2 +/- 0.5 to -1.8 +/- 0.5 after 12 months of GH treatment (P <.007 and P <.001, respectively). Baseline lumbar spine BMD was decreased when compared with that of a control group of children matched for bone age and height (0.645 +/- 0.09 g/cm(2) vs 0.730 +/- 0.08 g/cm(2); P <.003). Lumbar spine BMD increased in subjects with ISS after 1 year of GH treatment from 0.645 +/- 0.09 g/cm(2) to 0.808 +/- 0.04 g/cm(2) (P <.05), reaching levels similar to those of control subjects, followed up without therapy (0.808 +/- 0.04 g/cm(2) vs 0.760 +/- 0.08 g/cm(2)); lumbar spine BMD increased 25.3% in the subjects with ISS and 4.1% in the control subjects. Femoral neck BMD did not change during treatment. Serum concentrations of the carboxy-terminal propeptide of type 1 collagen increased from 231.6 +/- 65.5 microg/L to 351.6 +/- 87.2 microg/L, and levels of the carboxy-terminal cross-linked telopeptide of type 1 collagen increased from 9.9 +/- 5.9 microg/L to 13.9 +/- 2.4 microg/L. Children with ISS have decreased lumbar spine BMD, which increases with GH therapy, reaching levels similar to those of control subjects. Bone turnover increased as indicated by a rise in bone formation and bone resorption markers.

Effect of recombinant human erythropoietin on endothelial cell apoptosis.

BACKGROUND: Recombinant human erythropoietin (rHuEPO) induces endothelial cell growth and angiogenesis in vitro. The mechanisms are unknown. Because an increase in endothelial cell survival could play a role in this process, we examined the effect of rHuEPO on lipopolysaccharide (LPS)-induced apoptosis in bovine pulmonary artery endothelial cells (BPAECs). METHODS: Four groups of cells were studied. The first group was preincubated in serum-free medium followed by treatment with LPS. The second group was preincubated with rHuEPO followed by LPS. The third group was treated with only rHuEPO. Control cells were cultured in the absence of rHuEPO and LPS. Apoptosis was determined by flow cytometric DNA analysis, propidium iodide staining, cellular DNA fragmentation by ELISA, and gel electrophoresis. RESULTS: LPS-treated cells showed an increase in hypodiploid DNA (36.4 +/- 6.1%) compared with controls (9.8 +/- 3.3%, P < 0.001). Preincubation with rHuEPO decreased this effect to 14.7 +/- 5.1% (P < 0.001). Apoptosis determined by propidium iodide was observed in 33 +/- 8% of LPS-treated cells, but in only 9 +/- 3% of cells preincubated with rHuEPO cells (P < 0.001). Similarly, DNA fragmentation was decreased in rHuEPO pretreated cells compared with LPS alone (0.155 OD +/- 0.02 vs. 0.538 +/- 0.09 OD, P < 0.001). DNA breakdown was observed in only LPS-treated cells. CONCLUSIONS: These results suggest that rHuEPO prevents LPS-induced apoptosis in endothelial cells. This protective effect could be an important factor in the action of rHuEPO on vascular endothelium.

Magnesium and phosphorus.

A summary of new findings regarding alterations of magnesium (Mg2+) and phosphorus (P) metabolism are reviewed for the clinician caring for patients in general wards. Alterations in serum concentrations of Mg2+ and P are frequently observed in acute or very ill patients in emergency rooms or intensive-care areas. A significant proportion of these alterations are iatrogenic. Most of the symptoms related are non-specific, and usually they are associated with changes in concentration of other ions. The need to measure Mg2+ and P routinely and to define better the real abnormal values is stressed. Correction of the abnormalities must be early in the course of the alterations.

Decreased lumbar spine bone mass and low bone turnover in children and adolescents with insulin dependent diabetes mellitus followed longitudinally.

The effects of insulin dependent diabetes mellitus (IDDM) on bone metabolism are still not well defined. We evaluated total bone mineral content (TBMC) and bone mineral density (BMD) at the lumbar spine and femoral neck using dual X-ray absorptiometry in 26 IDDM children (15 M, 11 F) with a mean chronological age of 12.1+/-3.1 yr (range 7.1-14.2 yr). Duration of diabetes was 4.3+/-2.9 yr, with a mean glycosylated hemoglobin of 9.2+/-0.4%. BMD and TBMC standard deviation scores (Z-scores) were determined by comparing our results to controls matched for age, sex and pubertal status. BMD and bone formation and resorption markers were determined at the beginning of the study and after one year of follow up. Mean lumbar spine Z-score was -1.06+/-0.2, with negative values in 24 of 26 children (92.6%); 14/26 patients (53.8%) had a lumbar spine Z-score >1.0 SD below the mean. Mean lumbar spine Z-score remained unchanged after one year of follow up (-1.02+/-0.3). No significant differences were obtained in femoral neck BMD or TBMC between groups. No correlation was observed between lumbar spine BMD Z-scores and duration of IDDM or degree of diabetes control, as assessed by the mean glycosylated hemoglobin. Daily urinary calcium excretion was elevated in our patients initially and after one year of follow up; however, no correlation was obtained between lumbar spine BMD and 24 h urinary calcium excretion. Carboxy-terminal propeptide of type 1 collagen values and levels of urinary cross-linked N-telopeptides of type 1 collagen in the diabetic children were significantly lower than those of the matched controls. Osteoblastic activity as assessed by serum osteocalcin and by the carboxy-terminal propeptide of type I collagen and bone resorption as measured by cross-linked N-telopeptides of type 1 collagen did not correlate with the lumbar spine Z-scores. When IDDM patients were subdivided into males and females and into children with more than or less than 2 yr duration of diabetes since diagnosis, no differences between groups were found. These results suggest that insulin dependent diabetes in children is associated with low bone turnover resulting in a deficit in bone mass which may be manifested as osteopenia in the growing bone. This defect is already present in trabecular bone early on in the disease and seems not to be related to glycemic control.

Use of intrarenal needle manometry in acute renal dysfunction following renal transplantation.

Intrarenal manometry (IRM) using the Salaman fine-needle technique was routinely performed in 28 renal transplant patients in order to make the differential diagnosis of acute tubular necrosis, cyclosporin nephrotoxocity, and acute rejection. A total of 246 IRM determinations with simultaneous percutaneous renal biopsies were obtained in cases of acute renal failure following a renal transplant. Normal IRM values were 21.4 +/- 1.3 mm Hg. After collecting the clinical data, cyclosporin levels, ultrasound information, response to therapy, and renal biopsy results, we retrospectively obtained 49 IRM measurements in acute rejection, 9 in cyclosporin nephrotoxicity, and 26 in acute tubular necrosis. The values in acute rejection (41.3 +/- 9.5 mm Hg) were significantly different from the normally functioning kidneys, cyclosporin nephrotoxicity, or acute tubular necrosis. The values in cyclosporin nephrotoxicity were slightly elevated when compared to the normal or acute tubular necrosis determinations (p < 0.04) but were still significantly lower than the acute rejection. Our results suggest that IRM represents a useful technique in the approach to the acute renal dysfunction in renal transplant recipients.

[Role of bones in the physiopathology of idiopathic hypercalciuria: effect of amino-bisphosphonate alendronate]. / Papel del hueso en la fisiopatología de la hipercalciuria idiopática. Efecto del aminobisfosfonato alendronato.

Previous studies from our laboratory demonstrated that bone mineral content is affected in patients with idiopathic hypercalciuria and that there is a correlation between bone mineral loss and in-vitro cytokine production. At the same time we found that short term treatment with alendronate decreased urinary calcium in these subjects. In the present study we have examined the long-term effects of alendronate treatment (10 mg/day for one year) on urinary calcium, urinary hydroxyproline and bone mineral content in 18 idiopathic hypercalciuric and 8 normocalciuric stone formers. Clinical characteristics, as well as gender and age distribution were similar in both groups. Urinary calcium and hydroxyproline, were measured monthly. Calcium excretion decreased significantly at the end of the first month, and remained lower thereafter (277 +/- 28, before vs. 202 +/- 26 mg/g creatinine, after 12 months on alendronate, p < 0.01). Urinary hydroxyproline decreased significantly during the study (125.5 +/- 32.1 vs. 39.66 +/- 17.5 mg/g creatinine, p < 0.05). Serum calcium, glomerular filtration rate, and urinary sodium, did not change during the study. Lumbar spine bone density (trabecular bone) obtained with X ray absorptiometry revealed a significant increase from 1.162 +/- 0.231 to 1.197 +/- 0.248 g/cm2 (p < 0.01). These changes were associated with a significant decrease in IL-1 alpha mRNA transcription by unstimulated and lipopolysaccharide stimulated blood mononuclear cells, as tested by the reverse transcriptase polymerase chain reaction. No changes were observed in bone cortical sites (femoral neck). Normocalciuric subjects showed no significant changes in urinary calcium. In summary, the changes observed in urinary calcium excretion and different bone metabolic parameters, suggest a role of bone in the pathophysiology of idiopathic hypercalciuria.

Changes in bone mineral density, growth velocity and renal function of prepubertal uremic children during growth hormone treatment.

Thirteen prepubertal children with a mean chronological age of 6.7 +/- 3.4 years and severe chronic renal failure (mean glomerular filtration rate of 20.8 +/- 17.7 ml/min/1.73 m2) were studied. Patients received recombinant human growth hormone (rhGH) at a dose of 1 IU/kg/week given subcutaneously on a daily basis for 12 months. Mean growth rates of our patients increased significantly from a baseline level of 4.3 +/- 2.1 to 9.1 +/- 2.0 cm/year at 12 months of rhGH therapy. Mean height SDS improved from -3.5 +/- 1.0 at initiation of therapy to -2.6 +/- 1.3 at 12 months. Mean serum creatinine and blood urea nitrogen levels remained stable during the study, while mean glomerular filtration rates decreased initially and then stabilized; however, 2 subjects had a significant deterioration of their renal function at 6 and 9 months of rhGH, requiring discontinuing treatment. Before rhGH treatment, total bone mineral content as well as bone mineral density in cortical and trabecular bone were significantly reduced in our patients when compared to healthy controls paired for chronological age and similar to those of a healthy control group paired for bone age and height. Both these parameters increased significantly during rhGH treatment so that at 12 months our patients had values similar to those seen in a healthy control population paired to our patients for chronological age. While trabecular bone mineral density did not change in a group of untreated uremic controls during 12 months of follow-up, the percent of bone mineral density change in trabecular bone in our uremic patients during 12 months of rhGH treatment was very significant (p < 0.001) and larger than that noted in a group of healthy controls paired for bone age and height during 12 months of follow-up. This study demonstrates how rhGH treatment in prepubertal uremic children increases their growth velocity and their bone mineral density significantly, with an improvement in height for age. Careful followup of the renal function of patients in needed as they improve their height and bone mineral status.

Possible role of cytokines on the bone mineral loss in idiopathic hypercalciuria.

Decreased bone mass has been reported in patients with idiopathic hypercalciuria. Previous studies, using bioassays, have suggested a role of interleukin-1 (IL-1), in the decreased bone mineral density (BMD) of fasting hypercalciuria. The present study was designed to determine which IL-1 fraction (alpha or beta) correlates with bone resorption and whether other known bone resorting cytokines like interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) may play a role in this process. Cytokines production was determined by quantitative and specific analysis, enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR). Dual-energy X-ray absorptiometry and cytokine production by unstimulated and lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) were determined in a group of 29 patients with recurrent nephrolithiasis (17 hypercalciurics and 12 normocalciurics), and 12 healthy controls. The hypercalciuric subjects showed lower vertebral BMD than the normocalciuric or normal controls. There was no difference in spinal or femoral BMD between absorptive or fasting hypercalciurics. A significant negative correlation existed between urinary calcium excretion and vertebral BMD (r = -0.55, P < 0.01). Basal IL-1 alpha production correlated with vertebral BMD (r = -0.45, P < 0.02). This correlation was not seen with IL-1 beta, IL-6 or TNF-alpha production. LPS-induced IL-6 and TNF-alpha production were enhanced in the hypercalciuric patients, when compared to normocalciurics or controls. Control and normocalciuric subjects showed minimal amounts of IL-1 alpha mRNA. In contrast, hypercalciuric patients showed a significant increase of spontaneous IL-1 alpha mRNA transcription. These results suggest that different cytokines could be involved in the bone resorption process observed in hypercalciuria.