Bone metabolism in children with human immunodeficiency virus infection receiving highly active anti-retroviral therapy including a protease inhibitor.

We measured serum osteocalcin levels in prepubertal children with human immunodeficiency virus (HIV) infection receiving highly active antiretroviral therapy including a protease inhibitor and uninfected control children. Osteocalcin values were significantly elevated in the HIV-infected patients. Though osteocalcin serves as an index of bone formation, it likely functions as a negative regulator of bone formation. Further study is necessary to determine whether protease inhibitors normalize bone physiology or decrease bone formation and reduce bone mineral density in children receiving these therapies.

Genotype/phenotype observations in African Americans with Bartter syndrome.

BACKGROUND: Two Bartter syndrome phenotypes have been described, and molecular analyses demonstrate mutations in 1 of 3 genes encoding ascending limb of Henle transporters. We report phenotypic observations in 5 African American children with Bartter syndrome in the context of a distinct genotype. METHODS: Mutation analyses were performed in 5 unrelated African American children with Bartter syndrome. These results were correlated to clinical and laboratory data. Calcium metabolism was evaluated with a bone disk bioassay. RESULTS: Mutation analyses demonstrated homozygous deletion of the ClC-Kb gene in all children. Two children had polyhydramnios and premature birth; the others were born at term and presented with failure to thrive or dehydration. All receive indomethacin, spironolactone, and potassium chloride with improved but borderline hypokalemia. Growth has improved with therapy, but height SD scores range from -3.9- to -1.4. Urinary calcium excretion is normal, and bone disk bioassay shows no abnormal calciotropic activity. No patient had nephrocalcinosis, but renal sonograms show loss of corticomedullary differentiation. CONCLUSIONS: African Americans with Bartter syndrome genotyped to date have homozygous deletion of ClC-Kb Clinical observations in our patients include partial correction of hypokalemia and suboptimal growth despite therapy. Abnormal calciotropic activity and nephrocalcinosis are not seen, but renal ultrasounds are abnormal.

The technology-dependent child.

Improvements in the provision of oxygen, mechanical ventilation, tracheostomy care, enteral and parenteral nutrition, and dialysis have expanded the population of technology-dependent children. This article attempts to review pertinent points regarding these services, including common complications. Primary care and subspecialty physicians must smooth the transition of these children to the home environment, but a comprehensive team approach is necessary for the recognition of medical complications and provision of appropriate family teaching and psychosocial supports.

Urea kinetic analysis of automated peritoneal dialysis allows calculation of a CAPD-equivalent Kt/V(urea).

BACKGROUND: Based on evidence of increased mortality with decreasing urea clearance, the Dialysis Outcomes Quality Initiative (DOQI) recommended a weekly Kt/Vurea of 2.0 or higher for patients receiving continuous ambulatory peritoneal dialysis (CAPD). DOQI recommendations for automated peritoneal dialysis (APD) are based on efforts to determine the clearance providing urea mass removal equivalent to CAPD. We have adapted a variable volume direct quantitation urea kinetic model (UKM) in an effort to assess DOQI APD guidelines. METHODS: The daily urea mass removed with a weekly Kt/Vurea of 2.0 was calculated using standardized CAPD patient profiles. Using this value and defining the pre-APD plasma urea nitrogen (PUN) as C0 and equal to the CAPD steady-state PUN, the UKM reiteratively calculated the urea clearance from an APD treatment that provided a urea mass removal equivalent to CAPD. A total weekly Kt/Vurea was calculated for various levels of continuous urea clearance (defined as Kprt/Vurea) and plotted against Kprt/Vurea (weekly). The impact of dialytic time (t), drain volume of the daytime dwell (delta), and ultrafiltration volume (phi) were assessed, and all profiles were performed with C0 equal to the corresponding blood urea nitrogen of 60, 70, and 80 mg/dL. RESULTS: The relationship between requisite weekly Kt/Vurea and Kprt/Vurea (weekly) was linear. Weekly Kt/Vurea declined with increasing Kprt/Vurea, t, delta, and phi. The effect of phi on the weekly Kt/Vurea was independent of Kprt/Vurea, and the magnitude of the effect of t and delta on the weekly Kt/Vurea decreased with increasing continuous clearance. Weekly Kt/Vurea values were independent of V and C0. The latter observation allowed extrapolation of CAPD clearance and urea generation relationships to APD: CAPD-equivalent weekly Kt/Vurea = [700 x (UD + Ur)]/(C0 x V), where UD and Ur are the daily urea mass (mg) in dialysate and urine, respectively. CONCLUSIONS: The APD urea clearance, which provides urea mass removal equivalent to CAPD, varies as a function of a combination of patient and treatment variables. However, a CAPD-equivalent weekly Kt/Vurea can be calculated by collecting appropriate dialysis and urine samples and estimating patient V. The results can be evaluated in the context of evidence-based CAPD guidelines, increasing the precision of adjustment and monitoring of the APD prescription.

Bartter and Gitelman syndromes.

Since the initial description in the 1960s of patients with seemingly inherited disorders characterized by hypokalemia and metabolic alkalosis, the pathophysiologic processes underlying Bartter and Gitelman syndromes have generated tremendous study and speculation. Recently described mutations in genes encoding transport proteins important in sodium and chloride reabsorption in the thick ascending limb of Henle and distal convoluted tubule have confirmed these processes as the proximate defects in Bartter and Gitelman syndromes, respectively. Basic understanding of the role of these proteins in normal sodium and chloride homeostasis, and review of the secondary mediators stimulated by loss of their function provide insight into the clinical manifestations and response to treatment observed in these disorders.

Complications of removing percutaneous endoscopic gastrostomy tubes in children.

BACKGROUND: Little information has been reported regarding the frequency and type of complications arising from removal of percutaneous endoscopic gastrostomy (PEG) tubes in children. METHODS: The records of 397 patients who had PEG tubes placed from 1993 through 1998 were reviewed for complications after removal. Data collected included length of time the tube was in place, age of the patient at insertion, type of tube removed, and patient diagnosis. RESULTS: Fifty-four children had the PEG tube removed by traction or endoscopy. The only complication was persistent leaking through a gastrocutaneous fistula in 13 patients (24%). Leaking ceased in 6 children coincident with H2-antagonist therapy and silver nitrate cautery, and surgical closure of the fistula was required in 7 patients. Comparison of these 7 children with those who did not require surgery (n = 47) showed a longer duration of tube placement (mean +/- SE of 20.6+/-3.6 months, range 11-31 months vs. 11.1+/-1.3 months, range 1-35 months; P<0.05). Further analysis showed no child with a PEG tube removed before 11 months (n = 23) after insertion required surgery, whereas 7 (23%) of 31 children with a PEG tube removed after 11 or more months required surgery. Age at insertion, type of feeding device removed, and patient diagnoses were not different between the two groups. CONCLUSIONS: These data indicate that persistent leaking necessitating surgical closure of a gastrocutaneous fistula does not occur in children with a PEG tube removed within 11 months of insertion. In contrast, 23% of children with a PEG tube removed 11 or more months after insertion require surgery. In patients identified as candidates for tube removal, this time frame may be important in clinical decision making.

Center volume effects in pediatric renal transplantation. A report of the North American Pediatric Renal Transplant Cooperative Study.

An inverse relationship between mortality and center volume has been established for several surgical procedures. Given the distinctiveness of pediatric renal transplantation and the large variation in center volume, investigation for relationships between center volume and graft outcome was pursued using the North American Pediatric Transplant Cooperative Study database. Center volume groups were based on the total number of pediatric transplants reported from 1987 to 1995. Centers reporting > 100, 51-100, or < or = 50 transplants were grouped as high- (n=11), moderate- (n=28), or low-volume (n=65), respectively. Differences between groups included increasing rates of cadaver donor graft thrombosis (2.4%, 4.3%, and 5.7%, P<0.01) and acute tubular necrosis (ATN) (10.2%, 11.5%, and 14.0%, P<0.01) with decreasing center volume. Treatment differences included a higher rate of induction with an anti-T-cell antibody preparation in the larger-volume groups, 60.2%, 51.8%, and 39.2% (P<0.001). Decreasing graft survival for decreasing center size groups was noted at 3 months post transplant, 90.4%, 90.2%, and 88.4%. These differences were significant only with the exclusion of anti-T-cell induction from the proportional hazards model (relative risk=0.81 and =0.70 for the moderate- and high-volume groups, P<0.02). Superior graft survival in the high-volume centers noted at 3 months post transplant appears predominantly the result of lower rates of cadaver donor graft thrombosis and ATN. Analysis points to the need for low-volume centers to identify risk factors influencing these outcomes.

Conjunctive effects of fibroblast growth factor and glycosaminoglycan on bone metabolism in neonatal bartter syndrome.

The calciotropic activity of urine from a subject with neonatal Bartter syndrome (NBS) has been partially purified using ion-exchange and gel chromatographic techniques. A bioassay using bone disks from rat calvaria was used to estimate calciotropic activity, which in the urine of the subject with NBS appears to be due to basic fibroblast growth factor (bFGF) bound to a glycosaminoglycan susceptible to heparitinase digestion. The calciotropic activity is eluted from DEAE-Sephacel and Sepharose CL-6B in a narrow band in association with metachromatic material and is destroyed by heparitinase and blocked by an antibody to bFGF. After treatment of purified preparations with heparitinase, a component that is inactive alone but develops calciotropic activity in association with heparin can be isolated by affinity chromatography on heparin-Sepharose columns. This component is recovered from the column at NaCl concentrations expected to elute bFGF and is inactivated by antibodies to bFGF. No calciotropic activity can be shown in glycosaminoglycan-containing fractions from urine from a normal boy or a normal man, but such fractions exhibit calciotropic activity if bFGF is added to the assay system. When bFGF is added to urine from either normal subject followed by ion-exchange chromatography on DEAE-Sephacel, calciotropic activity is eluted at NaCl concentrations closely similar to those found to elute calciotropic activity from the urine of the NBS subject. It appears that the abnormal findings in NBS urine are due to excess bFGF, although they could be due to some abnormality of the glycosaminoglycan component.

Tubulointerstitial nephritis induced by the leukotriene receptor antagonist pranlukast.

A 7-year-old boy with asthma was receiving the leukotriene receptor antagonist pranlukast (Ultair; SmithKline Beecham; Pittsburgh) as part of an open-label clinical trial. The patient's asthma improved, and he remained asymptomatic; but routine study evaluations 9 to 12 months into therapy showed microhematuria, proteinuria, glucosuria, anemia, and renal insufficiency. Renal biopsy demonstrated changes classic for acute allergic tubulointerstitial nephritis (ATIN), with mixed interstitial inflammatory infiltrate including eosinophils. Within 6 months of pranlukast withdrawal, anemia resolved and urinary sediment and renal function normalized. The case demonstrates that hypersensitivity reaction to pranlukast and resultant ATIN is possible, and that periodic urine testing in patients receiving pranlukast should be considered.

Plasma creatinine results derived from an endpoint modification of the Jaffé method.

For values in the normal pediatric range, endpoint modifications of the Jaffé method for measuring plasma creatinine (PCr) yield higher results than other commonly used techniques. In an effort to evaluate the Olympus AU5000 endpoint method used by the large reference laboratory to which many of our patients are directed by their third-party payor, we compared results with a kinetic Jaffé technique using paired samples from the same specimens. In 46 samples, the kinetic method measured Pcr at < or =0.8 mg/dl, whereas the endpoint technique PCr was higher by 0.1 mg/dl in 6 (13%), 0.2 mg/dl in 23 (50%), and 0.3 mg/dl in 16 (35%) samples (P<0.0001). The combination of these higher values and the same reported normal range for all children ages 2-12 years (0.3-1.0 mg/dl) and 13-17 years (0.7-1.4 mg/dl) makes interpretation of Olympus AU5000 endpoint method results difficult, particularly for younger children. The results reinforce the need for each laboratory to provide comprehensive age- and sex-adjusted normal PCr ranges.

X-linked recessive nephrolithiasis: presentation and diagnosis in children.

We report a new X-linked recessive nephrolithiasis kindred. X-linked recessive nephrolithiasis is a recently described disease characterized by recurrent nephrolithiasis, nephrocalcinosis, and progressive renal failure, associated with mutations in a renal chloride channel gene, chloride channel number 5. Screening individuals at risk with renal ultrasonography and measurement of urinary excretion of low molecular weight proteins and calcium will exclude boys without X-linked recessive nephrolithiasis kindred and identify boys likely to have the disease.

Interleukin 1beta mediated calciotropic activity in serum of children with juvenile rheumatoid arthritis.

OBJECTIVE: To detect the presence and source of calciotropic activity in the serum of children with juvenile rheumatoid arthritis (JRA). METHODS: Metabolic evaluation of an adolescent with polyarticular JRA and hypercalcemia/hypercalciuria included testing with a bone disc bioassay. The bioassay detects calciotropic activity (increased bone resorption or reduced bone formation) in serum. Interleukin 1 receptor antagonist (IL-1RA) was added to patient sera to test the role of IL-1beta. The results in this index case prompted additional study in 9 children with JRA. Correlation of calciotropic activity with disease activity score, erythrocyte sedimentation rate (ESR), and urinary calcium excretion was by Spearman rank correlation. RESULTS: Calciotropic activity was found in 2 consecutive samples from the index patient. This activity was eliminated by addition of IL-1RA (p < 0.001 compared to serum alone). Testing of the other 9 children showed calciotropic activity at least once in 7/9 and 10/15 samples studied. Addition of IL-1RA completely (6/8) or partially (2/8) neutralized calciotropic activity (p < 0.001 compared to serum alone) in the specimens available for testing. Calciotropic activity did not significantly correlate with disease activity score, ESR, or urine calcium. CONCLUSION: Our data indicate the presence of IL-1beta mediated calciotropic activity in the sera of children with JRA, and suggest a role for IL-1beta in JRA associated osteopenia.

Factors influencing short-term and long-term pediatric renal transplant survival.

OBJECTIVE: To determine the patient and donor characteristics important for short-term and long-term renal transplant survival at Cincinnati Children's Hospital Medical Center. METHODS: Cumulative transplant survival was calculated and univariate analysis of graft survival performed on 206 transplants done since 1970 in 148 pediatric patients. Grafts to black recipients were analyzed separately. Short-term graft survival is defined as 1-year allograft survival and long-term graft survival as graft half-life (t1/2) survival for allografts functioning after the first posttransplant year. RESULTS: One-year graft survival of living-related donor (LRD) and cadaver donor (CAD) transplants was 77% and 62%, respectively. Graft t1/2 was 11.2 years for LRD and 9.8 years for CAD grafts. The CAD 1-year graft survival when the recipient or donor was younger than 7 years was 36% and 41%, respectively. The LRD 1-year graft survival to children younger than 7 years was 88% versus 75% in older children. Graft survival at 1 year was similar for CAD primary and retransplants (60% vs 65%), but graft t1/2 better for CAD primary grafts (17.8 years vs 5.0 years, P < 0.001). Preemptive LRD grafts performed similarity at 1 year and better over the long term compared with patients who had long-term dialysis (85% vs 74%, P = NS; and 16.9 years vs 8.0 years, p < 0.001). Preemptive CAD grafts did poorly, with 1-year graft survival of 38%. Administration of Cyclosporine A (CsA) improved CAD 1-year graft survival (76% vs 54%, p < 0.001) but not long-term survival. Thirty grafts to 24 black children had a 1-year survival of 48%, with no graft surviving more than 5 years. CONCLUSIONS: Living-related donor transplantation should be aggressively pursued for young children. If a LRD is unavailable and the young child's medical condition is stable, delay in CAD transplantation should be considered, with dialysis before transplant. Use of CsA improves 1-year pediatric graft survival, but does not improve graft survival after 1 year at the Children's Hospital Medical Center. New strategies to improve graft survival in black children should be pursued.

Occupational stress, safety, and health: conceptual framework and principles for effective prevention interventions.

The authors present an overarching conceptual model of occupational stress, safety, and health, incorporating multiple factors from diverse disciplines. They examine specific implications of the model for the development of prevention interventions (e.g., context-specific interventions and primary, secondary, and tertiary prevention). They review prevention interventions and describe and analyze 4 case studies that address exposure to environmental, ergonomic, and psychosocial stressors and a combination of physical-environmental and psychosocial stressors. The authors examine lessons learned from these interventions in light of the conceptual model (e.g., role of top management and integrating research and intervention).

Making the "new American workplace" safe and healthy: a joint labor-management-researcher approach.

The American workplace is now in the midst of the most significant change since the advent of mass production. Whether these changes will lead to improvements in worker health and safety is not clear. This paper describes an approach to intervention and research-participatory action research (PAR)-that has the potential to redesign work organizations to improve performance while also improving health and safety. In the PAR method, researchers, managers, workers, and unions collaborate in a process of data-guided problem solving intended both to improve the system's performance and to contribute to general scientific knowledge. A case study example illustrates the use of a PAR approach in an automobile parts facility where labor, management, and researchers jointly conducted a longitudinal project aimed at reducing the major sources of stress and enhancing employee well-being. Results from the 6 year project suggest that, properly implemented, PAR has the potential to both lead to improved intervention and contribute to theoretical advances in occupational safety and health. The PAR approach to intervention research is contrasted with the total quality approach (TQA), and some suggestions are made for improving PAR research designs.

C3-independent glomerulonephritis in guinea pigs: dependence upon primary humoral response.

We used C3-deficient (C3D) guinea pigs to evaluate the role of C3 in an active model of experimental nephritis. Normal strain 2 (C3N, n = 13) and C3D (n = 6) guinea pigs were immunized with cationized bovine gamma-globulin (CBGG). Fourteen days later (Day 0), daily intravenous injections of CBGG were given for 3 to 7 days and the animals were sacrificed on Day 10 or 21. Immunofluorescence (IF) microscopy of renal tissue revealed two patterns of glomerular IgG deposition: granular loop (11/13 C3N, 3/6 C3D), and predominantly mesangial (2/13 C3N, 3/6 C3D). Codeposited C3 was seen in all C3N and in no C3D animals. Electron microscopy showed subepithelial deposits in all. A significant correlation (P < 0.005) was seen between an animal's IF pattern and its level of serum antibodies to CBGG; those with lower antibody levels exhibited the mesangial pattern. C3D animals had lower mean antibody levels than C3N (P < 0.01), but both IF patterns were represented. Urine protein concentration, which was increased relative to controls, did not differ between C3N and C3D groups, but was significantly greater in those with loop IF. Serum albumin was significantly reduced in animals with loop IF. C3N animals showed a significant reduction in mean serum C3. In this model, immune deposit location and degree of proteinuria are independent of C3 deposition and dependent upon the level of antibody response to CBGG. Induction of antibody to CBGG is impaired in the absence of C3.

Designing a curriculum for healthy work: reflections on the United Automobile, Aerospace and Agricultural Implement Workers-General Motors Ergonomics Pilot Project.

An ambitious ergonomics pilot project sponsored by UAW-GM sought to bypass traditional "top-down" methods of ergonomics training in favor of an in-house "bottom-up" approach that empowered workers to implement basic ergonomic improvements in their own work areas. UAW and GM eventually used the program as the model for a corporate-wide ergonomics program that they later implemented.

A participatory approach to worksite health promotion.

A review of literature suggests that individual, social, and organizational factors are important to consider in the development of worksite health promotion programs. This article describes a conceptual framework that integrates these factors. The implications of this framework for the development, implementation, and evaluation of worksite health promotion programs and the results of an intervention based on this approach are presented. The results from this study highlight the importance of active employee involvement in all stages of worksite health promotion programs. The findings also indicate that programs need to address the causes, not just the symptoms, of stressful working conditions.

Hereditary angioneurotic oedema: characterization of plasma kinin and vascular permeability-enhancing activities.

The mediator(s) responsible for localized enhanced vascular permeability that characterizes an exacerbation of hereditary angioneurotic oedema (HAE) is thought to be a product of either contact or complement system activation. In contrast to normal individuals, plasma from these patients generates both kinin and vascular permeability-enhancing activity following incubation at 37 degrees C. Depletion of C1 inhibitor in both normal and C2-deficient plasma, but not in contact factor-deficient plasmas, resulted in generation of these activities. The kinin activity from incubated HAE plasma was susceptible to kininase inactivation and was blocked by a Bk2 receptor antagonist. Furthermore, this activity was isolated from HAE plasma; amino acid sequence analysis proved it to be bradykinin. Similarly, the vasopermeability-enhancing activity from ethanol-fractionated or boiled HAE plasma, collected during either attack or remission, co-eluted with bradykinin on reverse-phase high performance liquid chromatography (HPLC). These studies conclusively demonstrate that bradykinin is the major kinin and mediator of enhanced vascular permeability generated during incubation of HAE plasma. The role of other bioactive products, such as the C2 kinin, at local sites of oedema formation remains to be further defined.