Skeletal findings in the first 12 months following initiation of glucocorticoid therapy for pediatric nephrotic syndrome

Incident vertebral fractures and lumbar spine bone mineral density (BMD) were assessed in the 12 months following glucocorticoid initiation in 65 children with nephrotic syndrome. The incidence of vertebral fractures was low at 12 months (6 %) and most patients demonstrated recovery in BMD Z-scores by this time point.

INTRODUCTION

Vertebral fracture (VF) incidence following glucocorticoid (GC) initiation has not been previously reported in pediatric nephrotic syndrome.

METHODS

VF was assessed on radiographs (Genant method); lumbar spine bone mineral density (LS BMD) was evaluated by dual-energy X-ray absorptiometry.

RESULTS

Sixty-five children were followed to 12 months post-GC initiation (median age, 5.4 years; range, 2.3-17.9). Three of 54 children with radiographs (6 %; 95 % confidence interval (CI), 2-15 %) had incident VF at 1 year. The mean LS BMD Z-score was below the healthy average at baseline (mean ± standard deviation (SD), -0.5 ± 1.1; p = 0.001) and at 3 months (-0.6 ± 1.1; p < 0.001), but not at 6 months (-0.3 ± 1.3; p = 0.066) or 12 months (-0.3 ± 1.2; p = 0.066). Mixed effect modeling showed a significant increase in LS BMD Z-scores between 3 and 12 months (0.22 SD; 95 % CI, 0.08 to 0.36; p = 0.003). A subgroup (N = 16; 25 %) had LS BMD Z-scores that were ≤-1.0 at 12 months. In these children, each additional 1,000 mg/m(2) of GC received in the first 3 months was associated with a decrease in LS BMD Z-score by 0.39 at 12 months (95 % CI, -0.71 to -0.07; p = 0.017).

CONCLUSIONS

The incidence of VF at 1 year was low and LS BMD Z-scores improved by 12 months in the majority. Twenty-five percent of children had LS BMD Z-scores ≤-1.0 at 12 months. In these children, LS BMD Z-scores were inversely associated with early GC exposure, despite similar GC exposure compared to the rest of the cohort.

CO2 laser-based dispersion interferometer utilizing orientation-patterned gallium arsenide for plasma density measurements

A dispersion interferometer based on the second-harmonic generation of a carbon dioxide laser in orientation-patterned gallium arsenide has been developed for measuring electron density in plasmas. The interferometer includes two nonlinear optical crystals placed on opposite sides of the plasma. This instrument has been used to measure electron line densities in a pulsed radio-frequency generated argon plasma. A simple phase-extraction technique based on combining measurements from two successive pulses of the plasma has been used. The noise-equivalent line density was measured to be 1.7 × 10(17) m(-2) in a detection bandwidth of 950 kHz. One of the orientation-patterned crystals produced 13 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 13 W of peak power. Two crystals arranged sequentially produced 58 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 37 W of peak power.

The development of bone mineral lateralization in the arms

Bone mineral content (BMC) is known to be greater in the dominant arm after the age of 8 years. We studied a group of children and found that BMC sidedness gradually increased up to the age of 6 years and then remained stable into late adolescence.

INTRODUCTION

Bone mineral content (BMC) exhibits sidedness in the arms after the age of 8 years, but it is not known whether BMC is greater in the dominant arm from birth or whether lateralization develops in early childhood. To address this, we examined bone mineral status in relation to handedness and age.

METHODS

Subjects (N = 158) were children recently initiating glucocorticoids for underlying disease (leukemia 43 %, rheumatic conditions 39 %, nephrotic syndrome 18 %). Handedness was determined by questionnaire and BMC by dual-energy X-ray absorptiometry.

RESULTS

Median age was 7.2 years (range, 1.5 to 17.0 years), 49 % was male, and the spine BMD Z-score was -0.9 (SD, 1.3). By linear regression, BMC sidedness in the arms was significantly related to age (r = 0.294, p = 0.0005). Breakpoint analysis revealed two lines with a knot at 6.0 years (95 % CI, 4.5-7.5 years). The formula for the first line was: dominant:nondominant arm BMC ratio = 0.029 × age [in years] + 0.850 (r = 0.323, p = 0.017). The slope of the second line was not different from 0 (p = 0.332), while the slopes for the two lines were significantly different (p = 0.027).

CONCLUSIONS

These results show that arm BMC sidedness in this patient group develops up to age 6 years and then remains stable into late adolescence. This temporal profile is consistent with mechanical stimulation of the skeleton in response to asymmetrical muscle use as handedness becomes manifest.

Application of a national administrative case definition for the identification of pre-existing diabetes mellitus in pregnancy

INTRODUCTION

Accurate ascertainment of pregnant women with pre-existing diabetes allows for the comprehensive surveillance of maternal and neonatal outcomes associated with this chronic disease.

METHOD

To determine the accuracy of case definitions for pre-existing diabetes mellitus when applied to a pregnant population, a cohort of women who were pregnant in Nova Scotia, Canada, between 1991 and 2003 was obtained from a population-based provincial perinatal database, the Nova Scotia Atlee Perinatal Database (NSAPD). Person-level data from administrative databases using hospital discharge abstract data and outpatient physician services data were linked to this cohort. Various algorithms for defining diabetes mellitus from the administrative data, including the algorithm suggested by the National Diabetes Surveillance System (NDSS), were compared to a reference standard definition from the NSAPD.

RESULTS

Validation of the NDSS case definition applied to this pregnant population demonstrated a sensitivity of 87% and a positive predictive value (PPV) of 66.4%. Use of ICD-9 and ICD-10 diagnostic codes among hospitalizations with diabetes mellitus in pregnancy showed important increases in sensitivity and PPV, especially for those pregnancies delivered in tertiary centres. In this population, pregnancy-related administrative data from the hospitalization database alone appear to be a more accurate data source for identifying pre-existing diabetes than applying the NDSS case definition, particularly when pregnant women are delivered in a tertiary hospital.

CONCLUSION

Although the NDSS definition of diabetes performs reasonably well compared to a reference standard definition of diabetes, using this definition for evaluating maternal and perinatal outcomes associated with diabetes in pregnancy will result in a certain degree of misclassification and, therefore, biased estimates of outcomes.

Fluorescence measurements of expanding strongly coupled neutral plasmas

We report new detailed density profile measurements in expanding strongly coupled neutral calcium plasmas. Using laser-induced fluorescence techniques, we determine plasma densities in the range of 10(5) to 10(9) cm(-3) to with a time resolution limit as small as 7 ns. Strong coupling in the plasma ions is inferred directly from the fluorescence signals. Evidence for strong coupling at late times is presented, confirming a recent theoretical result.

Composite Carbon Paste Biosensor for Phenolic Derivatives Based on in Situ Electrogenerated Polypyrrole Binder

Amperometric biosensors based on new composite carbon paste (CPE) electrodes have been designed for the determination of phenolic compounds. The composite CPEs were prepared by in situ generation of polypyrrole (PPy) within a paste containing the enzyme polyphenol oxidase (PPO). The best paste composition (enzyme/pyrrole monomer/carbon particles/Nujol) was determined for a model enzyme, glucose oxidase, according to the enzymatic activity of the resulting electrodes and to the enzyme leakage from the paste during storage in phosphate buffer. The in situ electrogenerated PPy enables improvement in enzyme immobilization within the paste since practically no enzyme was lost in solution after 72 h of immersion. Moreover, the enzyme activity remains particularly stable under storage since the biocomposite structure maintains 80% of its activity after 1-month storage. Following the optimization of the paste composition, PPO-based carbon paste biosensors were prepared and presented excellent analytical properties toward catechol detection with a sensitivity of 4.7 A M(-1) cm(-2) and a response time lower than 20 s. The resulting biosensors were finally applied to the determination of epicatechin and ferulic acid as flavonol and polyphenol model, respectively.

Vertebral fractures in boys with Duchenne muscular dystrophy

Osteoporosis causes significant morbidity for boys with Duchenne muscular dystrophy. Corticosteroid therapy given to prolong mobility may increase the rate of osteoporosis and risk of fracture. This study of 33 boys with Duchenne muscular dystrophy determined retrospectively the incidence of vertebral fractures particularly after initiation of corticosteroids. A latency period of 40 months after commencement of steroids occurred before the first vertebral fracture appeared. However, by 100 months of treatment approximately 75% had sustained a vertebral fracture.

Does dietary protein intake correlate with markers suggestive of early diabetic nephropathy in children and adolescents with Type 1 diabetes mellitus?

AIMS

To examine the relationship between dietary protein intake and possible early markers of diabetic nephropathy (creatinine clearance (CrCI), kidney volume and albumin excretion rate (AER)).

METHODS

One hundred and forty-five subjects with diabetes for 5-10 years, divided into three pubertal groups, participated. Kidney volume was measured by ultrasound, and serum creatinine and HbA1c were assayed. Two or three 24-h urine collections were obtained for albumin, creatinine and urea excretion rates. Dietary protein intake was estimated from urinary urea nitrogen excretion rate. Glomerular filtration rate was estimated by creatinine clearance.

RESULTS

Mean protein intake was 1.22 +/- 0.48 g x kg(-1) x day(-1) Protein intake was significantly higher in males than females (P < 0.0001) and highest in prepubertal compared to mid-pubertal and post-pubertal subjects (P < 0.001). In multiple regression analysis, protein intake was positively associated with CrCl (P < 0.0001), and male sex (P < 0.0001) and negatively associated with body surface area (P = 0.0013) and age (P = 0.01). Kidney volume and AER were not related to dietary protein intake.

CONCLUSIONS

This cross-sectional study failed to show a significant relationship between dietary protein intake and markers of early nephropathy, other than CrCl. However, a longitudinal, prospective study is required to definitively assess the role of protein intake in the evolution of diabetic nephropathy.

Contribution of growth hormone and IGF-I to early diabetic nephropathy in type 1 diabetes

In children and adolescents with type 1 diabetes, we have reported an association between duration of puberty and the prevalence of nephromegaly and microalbuminuria (MA), which are early markers of diabetic nephropathy. Growth hormone (GH), IGF-I, testosterone, and prorenin are potential mediators of this effect. This study examined the relationship of these hormonal factors to kidney volume (KV) and MA in 155 subjects (78 males, age 13.2 +/- 3.5 years [mean +/- SD]) with similar diabetes duration (6.83 +/- 1.6 years) but varying pubertal experience (0-10 years). KV (by ultrasound), plasma IGF-I, testosterone, prorenin, and NaLi countertransport, and urinary albumin, urinary GH, and urinary IGF-I from three 24-h collections were measured. Multiple regression analysis showed that BSA (P < 0.0001) and urinary IGF-I (P = 0.001) were significantly associated with KV. MA subjects (albumin excretion rate 15-200 microg/min) had higher urinary IGF-I (P = 0.005) and urinary GH (P = 0.05) compared with normoalbuminuric subjects. Only 9% of the variance in urinary IGF-I could be attributed to plasma IGF-I (r = 0.30, P < 0.0001). Testosterone and prorenin were not associated with MA, but they were associated with KV in univariate analyses. The strong association of urinary IGF-I with KV, a marker for glomerular hypertrophy, and of both urinary IGF-I and urinary GH with MA suggests a role for these growth factors in the development of human diabetic nephropathy. Together, these data support animal studies that have shown that renal GH and IGF-I may contribute significantly to the pathogenesis of early diabetic nephropathy.

Testolactone-associated high androgen levels, a pharmacologic effect or a laboratory artifact?

Testolactone, an aromatase inhibitor, blocks conversion of androgens to estrogens. In familial male precocious puberty, slowing of pubertal progression and growth velocity occurs with testolactone and spironolactone. Girls with McCune-Albright syndrome, given testolactone, respond similarly. A 2-yr-old female (case 1) on testolactone for non-McCune-Albright gonadotropin independent precocious puberty had marked elevations of androstenedione (18 ng/mL, normal: 0.2-3.1) and testosterone (3.6 ng/mL, normal < 0.2) but no virilization. Investigations were undertaken to determine whether elevations in testosterone and androstenedione were caused by interference in these RIAs. After a single oral dose of testolactone (5 mg/kg in case 1; 4 mg/kg in case 2, a 3-yr-old boy with familial male precocious puberty; 10 mg/kg in a healthy postmenopausal control), serum testosterone and androstenedione were measured serially by RIA for 24 h. Androstenedione went from normal to a mean peak of 45.4 ng/mL at 1-2 h and returned to baseline by 24 h. Testosterone, undetectable at baseline (case 1 and control) or 1.8 ng/mL (case 2) rose to a mean peak of 6.9 ng/mL and returned to baseline by 24 h. Testolactone, in serial dilutions, cross-reacted in the testosterone assay. Testolactone significantly interferes in these serum RIAs, making their use unreliable in follow-up of patients treated with testolactone.

Kell blood group activity of gram-negative bacteria

To understand better the relationships between blood-group antigens and bacterial constituents, examples of 23 gram-negative bacteria (representing the 10 genera Citrobacter, Edwardsiella, Enterobacter, Escherichia, Klebsiella, Proteus, Pseudomonas, Salmonella, Serratia, and Shigella) were tested for the presence of Kl-like antigens by hemagglutination-inhibition (HAI) assays against both IgG and IgM anti-Kl. Saline-suspended whole organisms, cell-free culture media, and disrupted organisms were used to test for such antigens in, on, and secreted by the microorganisms examined. Disrupted organisms of an isolate of Shigella sonnei nonspecifically inhibited IgG anti-Kl as well as IgG antibodies of the specificities Kpb, Fya, S, and c. However, only Escherichia coli 0125:B15, subtype 12808, had specific K1-like activity (no activity with other IgG [(k, Kpb, Jka, Fya, S, c] and IgM [A, B, M, P1] antibodies). Disrupted organisms inhibited IgM but not IgG anti-K1 in the HAI assay. A second subtype, E. coli 0125:B15, subtype 12809, exhibited no K1-like activity. These findings support the report of K1 activity in cell-free broth cultures of E. coli 0125:B15 (subtype unspecified). Thus, although not all E. coli 0125:B15 possesses K1-like activity, the finding of such activity in at least one E. coli subtype confirms the idea that bacterial components may play a role in the production of naturally occurring antibodies directed against non-ABO red cell antigens.

Effect of pentoxifylline on Wrb antigen

Pentoxifylline, a hemorrheologic agent that lowers whole blood viscosity by increasing red cell membrane deformability, recently was approved by the Food and Drug Administration for the treatment of intermittent claudication. The effect of this drug on the phenotypic expression of red cell blood group antigens was studied with cells collected from six patients with intermittent claudication. After in vivo treatment with pentoxifylline, the serologic expression of the Wrb antigen increased. Comparative studies, using hemagglutination titration techniques, with red cells collected before treatment and 1 month after treatment, showed an increase in titer of at least two tubes and an increase in score of greater than 10 in all six patient samples drawn after treatment. No in vivo serologic changes were observed in any of the other antigens studied (A, B, D, C, E, c, e, M, N, S, s, U, P1, Leb, K, k, Fya, Fyb, Jka, Jkb, Yta). Protein analysis (sodium-dodecylsulfate polyacrylamide gel electrophoresis, silver stain) of red cell membranes prepared from blood collected before treatment and 1 month after treatment showed an increase in band density in the 24,000 and 14,000 dalton regions in the samples drawn after treatment. In vitro treatment of red cells with pentoxifylline and one of its major metabolites did not affect the phenotypic expression of any of the antigens studied, including Wrb.