Energy Requirement Is Higher During Weight-Loss Maintenance in Adults Consuming a Low- Compared with High-Carbohydrate Diet

BACKGROUND

Longer-term feeding studies suggest that a low-carbohydrate diet increases energy expenditure, consistent with the carbohydrate-insulin model of obesity. However, the validity of methodology utilized in these studies, involving doubly labeled water (DLW), has been questioned.

OBJECTIVE

The aim of this study was to determine whether dietary energy requirement for weight-loss maintenance is higher on a low- compared with high-carbohydrate diet.

METHODS

The study reports secondary outcomes from a feeding study in which the primary outcome was total energy expenditure (TEE). After attaining a mean Run-in weight loss of 10.5%, 164 adults (BMI ≥25 kg/m2; 70.1% women) were randomly assigned to Low-Carbohydrate (percentage of total energy from carbohydrate, fat, protein: 20/60/20), Moderate-Carbohydrate (40/40/20), or High-Carbohydrate (60/20/20) Test diets for 20 wk. Calorie content was adjusted to maintain individual body weight within ± 2 kg of the postweight-loss value. In analyses by intention-to-treat (ITT, completers, n = 148) and per protocol (PP, completers also achieving weight-loss maintenance, n = 110), we compared the estimated energy requirement (EER) from 10 to 20 wk of the Test diets using ANCOVA.

RESULTS

Mean EER was higher in the Low- versus High-Carbohydrate group in models of varying covariate structure involving ITT [ranging from 181 (95% CI: 8-353) to 246 (64-427) kcal/d; P ≤0.04] and PP [ranging from 245 (43-446) to 323 (122-525) kcal/d; P ≤0.02]. This difference remained significant in sensitivity analyses accounting for change in adiposity and possible nonadherence.

CONCLUSIONS

Energy requirement was higher on a low- versus high-carbohydrate diet during weight-loss maintenance in adults, commensurate with TEE. These data are consistent with the carbohydrate-insulin model and lend qualified support for the validity of the DLW method with diets varying in macronutrient composition. This trial was registered at clinicaltrials.gov as NCT02068885.

Effects of Dietary Carbohydrate Content on Circulating Metabolic Fuel Availability in the Postprandial State

Context

According to the carbohydrate-insulin model of obesity, an elevated insulin-to-glucagon ratio in response to a high-carbohydrate diet directs metabolic fuels toward storage, resulting in lower circulating energy.

Objective

To determine differences in total circulating energy post-meal related to dietary carbohydrate.

Design

Ancillary study within the Framingham State Food Study.

Setting

University community.

Participants

29 adults (aged 20 to 65 years) with overweight or obesity (body mass index ≥25 kg/m²)

Intervention

After achieving 10% to 14% weight loss on a run-in diet, participants were randomized to weight-loss-maintenance test diets varying in carbohydrate content (high-carbohydrate, 60% of total energy, n = 11; moderate-carbohydrate, 40%, n = 8; low-carbohydrate, 20%, n = 10) and controlled for protein (20%). During 24-hour metabolic ward admissions between 10 and 15 weeks on the test diets, metabolic fuels and hormones were measured.

Main Outcome Measure

Energy availability (EA) based on energy content of blood glucose, beta-hydroxybutyrate, and free fatty acids, in the late postprandial period (180 to 300 minutes). Insulin at 30 minutes into the test meal (Meal Insulin-30) was measured as an effect modifier.

Results

Insulin-to-glucagon ratio was 7-fold higher in participants on the high- vs low-carbohydrate diet (2.5 and 0.36, respectively). Late postprandial EA was 0.58 kcal/L lower on the high- vs low-carbohydrate diet (P < 0.0001), primarily related to suppression of free fatty acids. Early postprandial EA (30 to 180 minutes) declined fastest in the high-carbohydrate group, and Meal Insulin-30 modified this diet effect.

Conclusions

During weight-loss maintenance on a high-carbohydrate diet, late postprandial EA is reduced, consistent with the carbohydrate-insulin model.

Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial

OBJECTIVE

To determine the effects of diets varying in carbohydrate to fat ratio on total energy expenditure.

DESIGN

Randomized trial.

SETTING

Multicenter collaboration at US two sites, August 2014 to May 2017.

PARTICIPANTS

164 adults aged 18-65 years with a body mass index of 25 or more.

INTERVENTIONS

After 12% (within 2%) weight loss on a run-in diet, participants were randomly assigned to one of three test diets according to carbohydrate content (high, 60%, n=54; moderate, 40%, n=53; or low, 20%, n=57) for 20 weeks. Test diets were controlled for protein and were energy adjusted to maintain weight loss within 2 kg. To test for effect modification predicted by the carbohydrate-insulin model, the sample was divided into thirds of pre-weight loss insulin secretion (insulin concentration 30 minutes after oral glucose).

MAIN OUTCOME MEASURES

The primary outcome was total energy expenditure, measured with doubly labeled water, by intention-to-treat analysis. Per protocol analysis included participants who maintained target weight loss, potentially providing a more precise effect estimate. Secondary outcomes were resting energy expenditure, measures of physical activity, and levels of the metabolic hormones leptin and ghrelin.

RESULTS

Total energy expenditure differed by diet in the intention-to-treat analysis (n=162, P=0.002), with a linear trend of 52 kcal/d (95% confidence interval 23 to 82) for every 10% decrease in the contribution of carbohydrate to total energy intake (1 kcal=4.18 kJ=0.00418 MJ). Change in total energy expenditure was 91 kcal/d (95% confidence interval -29 to 210) greater in participants assigned to the moderate carbohydrate diet and 209 kcal/d (91 to 326) greater in those assigned to the low carbohydrate diet compared with the high carbohydrate diet. In the per protocol analysis (n=120, P<0.001), the respective differences were 131 kcal/d (-6 to 267) and 278 kcal/d (144 to 411). Among participants in the highest third of pre-weight loss insulin secretion, the difference between the low and high carbohydrate diet was 308 kcal/d in the intention-to-treat analysis and 478 kcal/d in the per protocol analysis (P<0.004). Ghrelin was significantly lower in participants assigned to the low carbohydrate diet compared with those assigned to the high carbohydrate diet (both analyses). Leptin was also significantly lower in participants assigned to the low carbohydrate diet (per protocol).

CONCLUSIONS

Consistent with the carbohydrate-insulin model, lowering dietary carbohydrate increased energy expenditure during weight loss maintenance. This metabolic effect may improve the success of obesity treatment, especially among those with high insulin secretion.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02068885.

An Academia-Industry Partnership for Planning and Executing a Community-Based Feeding Study

A research team from Boston Children's Hospital and Harvard Medical School conducted a community-based feeding study in collaboration with Framingham State University (FSU) and Sodexo, the food service contractor at FSU. The study was a randomized controlled trial, implemented on the FSU campus. For the final year of the study, a satellite feeding site was established at Assabet Valley Regional Technical High School. The purpose of the study was to assess the biological effects of different macronutrient diets. An academia-industry partnership was developed to overcome common challenges associated with hospital-based feeding studies. Benefits included the following: a study site outside of Boston (reducing inconvenience for participants), access to a large commercial kitchen and study-specific kiosk (promoting efficiency), collaboration with Sodexo chefs (ensuring palatability of meals), and opportunity to procure food from contracted vendors. The research (academia) and food service (industry) teams worked together to design, plan, and execute intervention protocols using an integrated approach. During execution, the research team was primarily responsible for overseeing treatment fidelity, whereas the food service team provided culinary expertise, with a strong focus on hospitality and food quality. The study was conducted in 3 cohorts between August 2014 and May 2017. Participants received all of their food for ∼30 wk, totaling >160,000 meals. For all 3 cohorts combined, 234 participants provided informed consent, 229 started a standard run-in weight-loss diet, 164 lost a mean ± SD 12% ± 2% of baseline body weight and were randomly assigned to different macronutrient diets for weight-loss maintenance, and 148 completed the study. During the final and largest cohort, as many as 114 participants received daily meals concurrently. The daily cost per participant for preparation and service of weighed meals and snacks was ∼$65. This academia-industry partnership provides a model for controlled feeding protocols in nutrition research, potentially with enhanced cost-effectiveness, practicality, and generalizability. This trial was registered at http://www.clinicaltrials.gov as NCT02068885.

A randomized study of dietary composition during weight-loss maintenance: Rationale, study design, intervention, and assessment

BACKGROUND

While many people with overweight or obesity can lose weight temporarily, most have difficulty maintaining weight loss over the long term. Studies of dietary composition typically focus on weight loss, rather than weight-loss maintenance, and rely on nutrition education and dietary counseling, rather than controlled feeding protocols. Variation in initial weight loss and insufficient differentiation among treatments confound interpretation of results and compromise conclusions regarding the weight-independent effects of dietary composition. The aim of the present study was to evaluate three test diets differing in carbohydrate-to-fat ratio during weight-loss maintenance.

DESIGN AND DIETARY INTERVENTIONS

Following weight loss corresponding to 12±2% of baseline body weight on a standard run-in diet, 164 participants aged 18 to 65years were randomly assigned to one of three test diets for weight-loss maintenance through 20weeks (test phase). We fed them high-carbohydrate (60% of energy from carbohydrate, 20% fat), moderate-carbohydrate (40% carbohydrate, 40% fat), and low-carbohydrate (20% carbohydrate, 60% fat) diets, controlled for protein content (20% of energy). During a 2-week ad libitum feeding phase following the test phase, we assessed the effect of the test diets on body weight.

OUTCOMES

The primary outcome was total energy expenditure, assessed by doubly-labeled water methodology. Secondary outcomes included resting energy expenditure and physical activity, chronic disease risk factors, and variables to inform an understanding of physiological mechanisms by which dietary carbohydrate-to-fat ratio might influence metabolism. Weight change during the ad libitum feeding phase was conceptualized as a proxy measure of hunger.

Allergic rhinitis

Chronic fatigue, recurrent otitis and sinusitis, and poor performance at school or at work are among the many physical and psychosocial consequences of allergic rhinitis. Antihistamines, decongestants, and nasal sprays may be used to treat many patients, but immunotherapy may be necessary or more practical in others. In all cases, control of the patient's home environment, particularly the bedroom, is essential.

Atenolol versus losartan in children and young adults with Marfan's syndrome

BACKGROUND

Aortic-root dissection is the leading cause of death in Marfan's syndrome. Studies suggest that with regard to slowing aortic-root enlargement, losartan may be more effective than beta-blockers, the current standard therapy in most centers.

METHODS

We conducted a randomized trial comparing losartan with atenolol in children and young adults with Marfan's syndrome. The primary outcome was the rate of aortic-root enlargement, expressed as the change in the maximum aortic-root-diameter z score indexed to body-surface area (hereafter, aortic-root z score) over a 3-year period. Secondary outcomes included the rate of change in the absolute diameter of the aortic root; the rate of change in aortic regurgitation; the time to aortic dissection, aortic-root surgery, or death; somatic growth; and the incidence of adverse events.

RESULTS

From January 2007 through February 2011, a total of 21 clinical centers enrolled 608 participants, 6 months to 25 years of age (mean [±SD] age, 11.5±6.5 years in the atenolol group and 11.0±6.2 years in the losartan group), who had an aortic-root z score greater than 3.0. The baseline-adjusted rate of change in the mean (±SE) aortic-root z score did not differ significantly between the atenolol group and the losartan group (-0.139±0.013 and -0.107±0.013 standard-deviation units per year, respectively; P=0.08). Both slopes were significantly less than zero, indicating a decrease in the aortic-root diameter relative to body-surface area with either treatment. The 3-year rates of aortic-root surgery, aortic dissection, death, and a composite of these events did not differ significantly between the two treatment groups.

CONCLUSIONS

Among children and young adults with Marfan's syndrome who were randomly assigned to losartan or atenolol, we found no significant difference in the rate of aortic-root dilatation between the two treatment groups over a 3-year period. (Funded by the National Heart, Lung, and Blood Institute and others; ClinicalTrials.gov number, NCT00429364.).

Characteristics of children and young adults with Marfan syndrome and aortic root dilation in a randomized trial comparing atenolol and losartan therapy

BACKGROUND

The Pediatric Heart Network designed a clinical trial to compare aortic root growth and other short-term cardiovascular outcomes in children and young adults with Marfan syndrome randomized to receive atenolol or losartan. We report here the characteristics of the screened population and enrolled subjects.

METHODS AND RESULTS

Between 2007 and 2011, 21 clinical sites randomized 608 subjects, aged 6 months to 25 years who met the original Ghent criteria and had a body surface area-adjusted aortic root diameter z-score >3.0. The mean age at study entry was 11.2 years, 60% were male, and 25% were older teenagers and young adults. The median aortic root diameter z-score was 4.0. Aortic root diameter z-score did not vary with age. Mitral valve prolapse and mitral regurgitation were more common in females. Among those with a positive family history, 56% had a family member with aortic surgery, and 32% had a family member with a history of aortic dissection.

CONCLUSIONS

Baseline demographic, clinical, and anthropometric characteristics of the randomized cohort are representative of patients in this population with moderate to severe aortic root dilation. The high percentage of young subjects with relatives who have had aortic dissection or surgery illustrates the need for more definitive therapy; we expect that the results of the study and the wealth of systematic data collected will make an important contribution to the management of individuals with Marfan syndrome.

Overview of pediatric bone problems and related osteoporosis

Osteoporosis is a well-established clinical problem in adults. Osteoporosis in pediatrics, on the other hand, is a new and evolving area, with certain unique diagnostic and clinical challenges. Recently, there has been an increased awareness of osteoporosis in children, both as a primary problem due to genetic mutations and enzyme deficiencies, and as secondary to various diseases, medications, and lifestyle issues. In this review we discuss the common forms of osteoporosis, including candidate genes, mutations of which can lead to primary osteoporosis, the mechanisms involved in the pathogenesis of secondary bone loss, and possible ways of diagnosing, preventing, or treating these conditions. The purpose of the article is to provide a summary of our current knowledge of pediatric bone problems and to provide a basis for discussion of the most appropriate ways to detect, treat, or prevent such problems.

Lessons learned from a pediatric clinical trial: the Pediatric Heart Network angiotensin-converting enzyme inhibition in mitral regurgitation study

BACKGROUND

Mitral regurgitation is the most common indication for reoperation in children following repair of atrioventricular septal defect (AVSD). We hypothesized that angiotensin-converting enzyme inhibitor therapy would decrease the severity of mitral regurgitation and limit left ventricular volume overload in children following AVSD repair.

METHODS

The Pediatric Heart Network designed a placebo-controlled randomized trial of enalapril in this population. The primary aim was to test the effect of enalapril on the change in left ventricular end-diastolic dimension body surface area-adjusted z score. Before the launch of the trial, a feasibility study was performed to estimate the number of patients with at least moderate mitral regurgitation following AVSD repair.

TRIAL EXPERIENCE

Seventeen months after the start of the study, 349 patients were screened, 8 were trial eligible, and only 5 were enrolled. The study was subsequently terminated because of low patient accrual. Several factors led to the problems with patient accrual, including (1) the use of criteria to assess disease severity in the feasibility study that were not identical to those used in the trial, (2) failure to achieve equipoise for the study among clinicians and referring physicians, (3) reliance on methodology developed in adult populations with different disease mechanisms, and (4) absence of adequate data to define the natural history of the disease process under study. Progress in the treatment of children with cardiovascular disease will depend on the future of multicenter collaborative clinical trials. The lessons learned from this study may contribute to improvements in this research.

Partial and transitional atrioventricular septal defect outcomes

BACKGROUND

Surgical and perioperative improvements permit earlier repair of partial and transitional atrioventricular septal defects (AVSD). We sought to describe contemporary outcomes in a multicenter cohort.

METHODS

We studied 87 patients undergoing primary biventricular repair of partial or transitional AVSD between June 2004 and February 2006 across seven North American centers. One-month and 6-month postoperative data included weight-for-age z-scores, left atrioventricular valve regurgitation (LAVVR) grade, residual shunts, and left ventricular ejection fraction. Paired methods were used to assess 6-month change.

RESULTS

Median age at surgery was 1.8 years; median weight z-score was -0.88. Median days for ventilation were 1, intensive care 2, and hospitalization 5, all independent of age, with 1 in-hospital death. At 1 month, 27% (16 of 73) had ejection fraction less than 55%; 20% (17 of 87) had significant LAVVR; 2 had residual shunts; 1 each had subaortic stenosis and LAVV stenosis. At 6 months (n = 60), there were no interim deaths, reinterventions, or new development of subaortic or LAVV stenosis. Weight z-score improved by a median 0.4 units (p < 0.001), especially for underweight children less than 18 months old. Left atrioventricular valve regurgitation occurred in 31% (change from baseline, p = 0.13), occurring more frequently in patients repaired at 4 to 7 years (p = 0.01). Three patients had ejection fraction less than 55%, and 1 had a residual atrial shunt.

CONCLUSIONS

Surgical repair for partial/transitional AVSD is associated with low morbidity and mortality, short hospital stays, and catch-up growth, particularly in underweight children repaired between 3 and 18 months of age. Left atrioventricular valve regurgitation remains the most common residual defect, occurring more frequently in children repaired after 4 years of age.

Associated symptoms in the ten days before diagnosis of Kawasaki disease

OBJECTIVE

To describe common associated symptoms within the 10 days before diagnosis in subjects enrolled in the Pediatric Heart Network's trial of steroid therapy in Kawasaki disease (KD).

STUDY DESIGN

Patients with acute KD were enrolled between days 4 and 10 of illness at 8 centers between 2002 and 2004. We defined common associated symptoms as those occurring in >or=10% of patients. Principal clinical criteria for KD were not included in this analysis.

RESULTS

Among 198 patients, irritability was reported in 98 (50%), vomiting in 88 (44%), decreased food/fluid intake in 73 (37%), cough in 55 (28%), diarrhea in 52 (26%), rhinorrhea in 37 (19%), weakness in 37 (19%), abdominal pain in 35 (18%), and joint pain (arthralgia or arthritis) in 29 (15%). One or more gastrointestinal symptom (vomiting, diarrhea, or abdominal pain) was present in 120 patients (61%) and 69 patients (35%) had >or= 1 respiratory symptom (rhinorrhea or cough).

CONCLUSIONS

Nonspecific symptoms occur commonly in children with KD. To reduce delays in diagnosis, clinicians should be educated that such symptoms may comprise a significant component in the chief complaint.

Delayed diagnosis of Kawasaki disease: what are the risk factors?

OBJECTIVE

Because late diagnosis of Kawasaki disease increases the risk for coronary artery abnormalities, we explored the prevalence of and possible risk factors for delayed diagnosis by using the database of the Pediatric Heart Network trial of corticosteroid treatment for Kawasaki disease.

METHODS

We collected sociodemographic and clinical data at presentation for all patients who were treated for presumed Kawasaki disease at 8 centers (7 in the United States, 1 in Canada). Delayed diagnosis was evaluated by total number of illness days to diagnosis and by the percentage of patients who were treated after day 10 of illness. Independent predictors of delayed diagnosis were identified by using multivariate linear and logistic regression.

RESULTS

Of the 589 patients who received intravenous immunoglobulin, 27 were treated before screening for the trial and excluded; 562 patients formed the cohort for analysis. Kawasaki disease was diagnosed at 7.9 +/- 3.9 days, 92 (16%) cases after day 10. Centers were similar with respect to patient age and gender. Centers differed in the patient percentage with incomplete Kawasaki disease; clinical criteria of cervical adenopathy, oral changes, and conjunctivitis; and distance of residence from the center. Independent predictors of greater number of illness days at diagnosis included center, age of <6 months, incomplete Kawasaki disease, and greater distance from the center. Independent predictors of diagnosis after day 10 were age of <6 months, incomplete Kawasaki disease, and greater distance). Socioeconomic variables had no association with delayed diagnosis.

CONCLUSIONS

Even after adjustment for patient factors, illness duration at diagnosis varies by center. These findings underscore the need to maintain a high index of suspicion of Kawasaki disease in the infant who is younger than 6 months and has prolonged fever even with incomplete criteria. Outreach educational programs may be useful in promoting earlier recognition and treatment of Kawasaki disease.

Rationale and design of a randomized clinical trial of beta-blocker therapy (atenolol) versus angiotensin II receptor blocker therapy (losartan) in individuals with Marfan syndrome

BACKGROUND

Cardiovascular disease, including aortic root dilation, dissection, and rupture, is the leading cause of mortality in patients with Marfan syndrome (MFS). The maximal aortic root diameter at the sinuses of Valsalva is considered the best predictor of adverse cardiovascular outcome. Although advances in therapy have improved life expectancy, affected individuals continue to suffer cardiovascular morbidity and mortality. Recent studies in an FBN1-targeted mouse model of MFS with aortic disease similar to that seen in humans showed that treatment with losartan normalized aortic root growth and aortic wall architecture.

METHODS

The Pediatric Heart Network designed a randomized clinical trial to compare aortic root growth and other short-term cardiovascular outcomes in subjects with MFS receiving atenolol or losartan. Individuals 6 months to 25 years of age with a body surface area-adjusted aortic root z score >3.0 will be eligible for inclusion. The primary aim is to compare the effect of atenolol therapy with that of losartan therapy on the rate of aortic root growth over 3 years. Secondary end points include progression of aortic regurgitation; incidence of aortic dissection, aortic root surgery, and death; progression of mitral regurgitation; left ventricular size and function; echocardiographically derived measures of central aortic stiffness; skeletal and somatic growth; and incidence of adverse drug reactions.

CONCLUSION

This randomized trial should make a substantial contribution to the management of individuals with MFS and expand our understanding of the mechanisms responsible for the aortic manifestations of this disorder.

Randomized trial of pulsed corticosteroid therapy for primary treatment of Kawasaki disease

BACKGROUND

Treatment of acute Kawasaki disease with intravenous immune globulin and aspirin reduces the risk of coronary-artery abnormalities and systemic inflammation, but despite intravenous immune globulin therapy, coronary-artery abnormalities develop in some children. Studies have suggested that primary corticosteroid therapy might be beneficial and that adverse events are infrequent with short-term use.

METHODS

We conducted a multicenter, randomized, double-blind, placebo-controlled trial to determine whether the addition of intravenous methylprednisolone to conventional primary therapy for Kawasaki disease reduces the risk of coronary-artery abnormalities. Patients with 10 or fewer days of fever were randomly assigned to receive intravenous methylprednisolone, 30 mg per kilogram of body weight (101 patients), or placebo (98 patients). All patients then received conventional therapy with intravenous immune globulin, 2 g per kilogram, as well as aspirin, 80 to 100 mg per kilogram per day until they were afebrile for 48 hours and 3 to 5 mg per kilogram per day thereafter.

RESULTS

At week 1 and week 5 after randomization, patients in the two study groups had similar coronary dimensions, expressed as z scores adjusted for body-surface area, absolute dimensions, and changes in dimensions. As compared with patients receiving placebo, patients receiving intravenous methylprednisolone had a somewhat shorter initial period of hospitalization (P=0.05) and, at week 1, a lower erythrocyte sedimentation rate (P=0.02) and a tendency toward a lower C-reactive protein level (P=0.07). However, the two groups had similar numbers of days spent in the hospital, numbers of days of fever, rates of retreatment with intravenous immune globulin, and numbers of adverse events.

CONCLUSIONS

Our data do not provide support for the addition of a single pulsed dose of intravenous methylprednisolone to conventional intravenous immune globulin therapy for the routine primary treatment of children with Kawasaki disease. (ClinicalTrials.gov number, NCT00132080 [ClinicalTrials.gov].)

The effect of prolonged euglycemic hyperinsulinemia on lean body mass after severe burn

BACKGROUND

The hypermetabolic response to burn increases protein catabolism. Euglycemic hyperinsu-linemia with exogenous insulin maintains muscle protein by continued stimulation of net protein synthesis. Our aim was to determine the effect of euglycemic hyperinsulinemia over the entire hospitalization on muscle anabolism by investigating lean body mass (LBM) as the primary endpoint.

METHODS

Eighteen subjects between the ages of 2 and 18 with burns of more than 40% were prospectively randomized into 2 groups, a control (n = 9) and a treatment group (n = 9). The treatment group was given continuous intravenous insulin at a rate of at least 1.5 microU/kg/min to maintain serum glucose levels between 100 to 140 mg/dL. Treatment was instituted 24 to 48 hours after arrival and continued until the patient's injury was 95% healed. All patients received continuous enteral feeding. Patients underwent body composition studies by dual-energy x-ray absorptiometry (DEXA) scan on postoperative day 6 after initial burn excision and when 95% healed.

RESULTS

Nutritional intakes were not different between groups. In the control, subjects continued catabolism resulted in peripheral muscle wasting and centripetal obesity with diminished truncal LBM. The treatment group had improvement in lean body mass (P =.004) and bone mass (P =.025). The treatment group also had less peripheral muscle wasting with overall increases in upper/lower extremity LBM (P =.005). Hospital length of stay in days per percent of total body surface area burned was decreased in the insulin group (control = 1.03 +/- 0.1 vs 0.7 +/- 0.9 for insulin patients; P <.05).

CONCLUSIONS

Euglycemic hyperinsulinemia throughout the hospital course mitigates muscle catabolism and preserves lean body mass.

Up-regulation of the parathyroid calcium-sensing receptor after burn injury in sheep: a potential contributory factor to postburn hypocalcemia

OBJECTIVE

To test the hypothesis that the hypocalcemia and hypoparathyroidism that follow severe burn injury are related to up-regulation of the parathyroid gland calcium-sensing receptor (CaR), which may reduce the set-point for suppression of circulating parathyroid hormone by blood calcium.

DESIGN

A controlled but unblinded study.

SETTING

An investigational intensive care unit.

SUBJECTS

Female range ewes.

INTERVENTION

Sheep were subjected to a 40% total body surface area burn under anesthesia (n = 9) or sham burn receiving anesthesia and fluid resuscitation only (n = 8) and were killed 48 hrs postburn.

MEASUREMENTS AND RESULTS

Blood ionized calcium, magnesium, and creatinine, and urinary calcium, magnesium, and creatinine were monitored for 48 hrs. After the sheep were killed, parathyroids (burn group, n = 3; sham group, n = 4) and kidneys (n = 4, each group) were harvested, snap frozen in liquid nitrogen, and analyzed for CaR messenger ribonucleic acid (mRNA) by Northern blot, and were analyzed for CaR cell-surface staining by immunocytochemistry with a polyclonal CaR-specific antiserum (parathyroids only). Bumed sheep were hypocalcemic and hypomagnesemic compared with sham-burned control sheep. CaR mRNA was increased by 50% (p < 0.005, analysis of variance) with a corresponding increase in the intensity of CaR immunoreactivity associated with the cell surface in parathyroids obtained from burned (n = 3) compared with sham-burned (n = 2) sheep. These findings are consistent with up-regulation of the parathyroid CaR and a related decrease in set-point for calcium suppression of parathyroid hormone secretion that may contribute to the previously reported postburn hypoparathyroidism and hypocalcemia.

Persistent hypoparathyroidism following magnesium repletion in burn-injured children

Children suffering severe burns develop hypocalcemia, magnesium (Mg) depletion, hypoparathyroidism, and renal resistance to parathyroid hormone (PTH) infusion. We hypothesized that Mg depletion accounted for both the hypoparathyroidism and the renal resistance to PTH, and that Mg repletion would improve both. Due to a lack of PTH for infusion, we studied only the effect of Mg repletion on the relationship between ionized Ca (iCa) and PTH in the serum of 14 sequentially recruited children burned > or =40% total body surface area. All received a urinary Mg retention test a median of 20 days post burn (range 8-137 days). Seven (50%) of the children remained Mg depleted, which was not attributable to burn size or to time from burn to study. Combined enteral and parenteral Mg intakes were not different between the depleted and repleted groups, 12.2+/-4.4 (SD) mg/kg per day and 14.2+/-6.2 mg/kg per day, respectively. Both groups had low intact PTH levels in relation to serum iCa concentration, indicating persistent hypoparathyroidism. We conclude that Mg depletion is not the chief cause of hypoparathyroidism following thermal injury and we postulate that the persistent hypoparathyroidism is consistent with a reduced set-point for Ca suppression of PTH secretion.

Bone turnover in preterm infants

Total parenteral nutrition is associated with osteopenia in preterm infants. Insufficient calcium and phosphate are likely causes: aluminum contamination is another possible contributing factor as this adversely affects bone formation and mineralization. The study was designed to evaluate changes in biochemical markers of bone turnover in 22 preterm infants receiving total parenteral nutrition in comparison with 19 term infants. We collected urine and serum samples from 22 preterm infants, mean gestational age 29 wk, within 48 h and again at 3 wk of life. We also collected urine samples from 19 term infants, mean gestational age 39 wk, during the first day of life. Bone resorption was assessed by the measurement of urinary pyridinium cross-links by HPLC and ELISA and the N-telopeptide of type I collagen by ELISA. Bone formation was assessed in premature infants by the measurement of serum osteocalcin. The N-telopeptide of type I collagen was higher in the preterm infants compared with term at baseline (p < 0.01). There was no difference between the pyridinium cross-links in the preterm and term infants. All the biochemical markers of bone turnover increased significantly in the preterm infants during the first 3 wk of life, e.g. N-telopeptide was a 153% change from baseline (p < 0.001). Aluminum in the total parenteral nutrition solutions did not cause a decrease in bone formation at the level administered (3-6 microg, 0.1-0.2 micromol x kg(-1) x d(-1)).

The role of bone densitometry in the diagnosis and management of the severely burned patient with bone loss

Children and adults who suffer severe burn injuries develop abnormalities in bone and mineral metabolism. The most prominent of these is a reduction in bone formation. Events occurring immediately following burn injury that are likely contributors to the reduced bone formation include an increase in endogenous glucocorticoid production, functional growth hormone deficiency, hypoparathyroidism, and interoperative immobilization. The proinflammatory cytokines interleukin-1 beta and interleukin-6 may also contribute. To date, the effects of burn injury on bone formation have been equivocal. However, the major reduction in bone formation without any consistent change in resorption suggests an uncoupling of formation and resorption. A consequence of this is lumbar spine bone loss as detected by dual-energy X-ray absorptiometry by 6 wk postburn. In both cross-sectional and longitudinal studies, the initial low bone density remains decreased in relation to unburned age-matched peers. The reduced bone density increases the risk for postburn fractures and for reduced peak bone mass, increasing the risk of these patients for adult-onset osteoporosis.

Ciprofloxacin as a therapeutic modality in pediatric burn wound infections: efficacious or contraindicated?

BACKGROUND

Food and Drug Administration regulations state that ciprofloxacin hydrochloride may cause arthropathies. For this reason, such therapy is contraindicated in the pediatric population. However, several studies in children with cystic fibrosis have found the drug to be efficacious. Our hypothesis was that ciprofloxacin treatment is justified in the case of multiresistant organisms in burn populations.

DESIGN

During a 4-year period (January 1, 1993, to December 31, 1997) we treated 56 of our pediatric burn patients with ciprofloxacin when cultures proved resistant to other antibiotics. The burn area was 65% of the total body surface area. The average patient age was 8.4 years. Of the 56 patients who received ciprofloxacin, 50 received the recommended dose. Biopsy specimens were assessed for quantitative bacteriology and antibiotic sensitivity. Radiologic review was conducted to examine for arthropathy.

RESULTS

All patients showed unequivocal reduction in quantitative bacterial counts, and susceptibility to ciprofloxacin remained stable without the development of resistance. Of the 56 patients treated, 42 had a major reduction in their quantitative wound biopsies from 10(6) to less than 100 colonies per gram of tissue, while the remaining 14 were observed to have a 2- to 3-log decrease. No arthropathy was detected in any of the 56 patients receiving ciprofloxacin. Review of the patients' charts showed no documented adverse events associated with the use of ciprofloxacin. All patients survived their thermal injury and the complications associated with it without any untoward problems or complications of arthropathy.

CONCLUSION

On the basis of these data, ciprofloxacin therapy in the treatment of immunosuppressed pediatric burn patients is efficacious and does not cause arthropathy.

Magnesium deficit in major burns: role in hypoparathyroidism and end-organ parathyroid hormone resistance

Children and adults who are severely burned develop magnesium(Mg) depletion, hypocalcemia, hypoparathyroidism and renal resistance to the administration of exogenous parathyroid hormone(PTH). This same spectrum of findings is seen with both Mg depletion and hypermagnesemia. We reported that in a group of ten children burned at least 30 per cent of total body surface area that 70-80 per cent of serum levels of ionized calcium and Mg were low. In three of the patients studies when serum Mg returned to normal, retention of a standard Mg infusion was abnormally high in two of them, suggesting persistence of Mg depletion despite normal serum Mg levels. Mg intake in these children conforms to the recommended dietary intake for age suggesting that excessive Mg losses may contribute to the observed Mg depletion. These losses are through the burn wound and possibly through abnormal intestinal secretion. Increased metabolic rate seen in burn patients may also promote intracellular Mg uptake to support the increased energy requirements of cells. It is hypothesized that since Mg is an important cofactor in the production of cyclic AMP, Mg deficiency may block intracellular cyclic AMP generation in parathyroid cells to block the secretion of parathyroid hormone and in renal tubular cells to block the renal generation may improve PTH secretion and hypocalcemia in non-burned patients, preliminary data in burned children suggest that the cause of hypocalcemia and hypoparathyroidism is more complex.

Ciprofloxacin versus cefuroxime axetil in the treatment of adult patients with acute bacterial sinusitis

OBJECTIVE

This study compared the use and efficacy of ciprofloxacin to cefuroxime axetil for adult patients with acute bacterial sinusitis.

METHOD

We conducted a prospective, randomized, double-blind pilot study of oral ciprofloxacin (500 mg twice daily) versus cefuroxime axetil (250 mg twice daily) for 2 to 3 weeks in the treatment of adult patients with a clinical diagnosis of acute bacterial maxillary sinus infections or acute exacerbation of chronic bacterial sinusitis. Patients with microbiologically and radiologically confirmed sinusitis infection composed the efficacy population.

RESULTS

Of the 83 patients enrolled, 13 of 42 (31%) ciprofloxacin- and 19 of 41 (46%) cefuroxime axetil-treated patients had a respiratory pathogen isolated from a sinus aspiration. The most frequent pretherapy isolated included Haemophilus influenzae (11), streptococcus species (20), staphylococcus species (7), Proteus mirabilis (3), and Neisseria sicca (3). At the end of therapy, clinical resolution or improvement in efficacy-valid patients was achieved in 12 (100%) ciprofloxacin-treated patients and in 14 (74%) cefuroxime axetil recipients. The five (26%) cefuroxime axetil clinical failures were due to development of superinfection. Bacteriologic eradication occurred in 12 (100%) and 14 (100%) ciprofloxacin and cefuroxime axetil patients, respectively. Similar clinical and bacteriologic response rates were observed at the 2- to 4-week follow-up. Among 83 intent-to-treat patients, 19 (45%) ciprofloxacin and 14 (34%) cefuroxime axetil patients had drug-related adverse events. The most common adverse event in both treatment groups was gastrointestinal.

CONCLUSION

This pilot study suggests that ciprofloxacin is efficacious in the management of acute bacterial sinusitis.

The management of acute bone loss in severe catabolism due to burn injury

Reduced bone formation has been documented in both children and adults following burn injury of > or = 40% total body surface area. In children, reduced bone formation and hypercalciuria may be the underlying causes of acute and sustained reduction in bone mineral density. The possible consequences of this reduction are an increase in extrapolated annual fracture incidence and reduced peak bone mass. Excessive endogenous glucocorticoid production, immobilization, bone marrow suppression, and magnesium depletion are all postulated as underlying causes. The most promising potential management agent is recombinant human growth hormone, which can stimulate bone formation via production of insulin-like growth factor I(IGF-I) and its associated binding protein, IGFBP-3, which correlates with bone mineral density in adults. Long-term treatment may be necessary to see a positive effect on bone formation and bone density. Correcting any detected magnesium depletion, and exercise as tolerated, are two other management strategies that might improve bone formation in this population.

Metabolic bone disease of total parenteral nutrition

Parenteral nutrition-associated metabolic bone disease in children is manifested primarily as osteopenia and, on occasion, fractures. The etiology is likely multifactorial, with calcium and phosphate deficiency playing a major role in the preterm infant and with the role of aluminum toxicity yet to be clearly defined in this population. Lack of normal values of bone histomorphometry in the premature infant as well as lack of normal data for biochemical markers of bone turnover in these patients contribute to the uncertainty. Other factors that may play a role in the pathogenesis include lack of periodic enteral feeding; underlying intestinal disease, including malabsorption and inflammation; the presence of neoplasms; and drug-induced alterations in calcium and bone metabolism. The true incidence and prevalence of parenteral nutrition-associated bone abnormalities in pediatric patients remain unknown.

Comparative study of the clinical effectiveness of a pyrethrin-based pediculicide with combing versus a permethrin-based pediculicide with combing

In a randomized, evaluator-blinded clinical trial, 190 patients were treated for Pediculus humanus capitis infestations with a pyrethrin-piperonyl-butoxide pediculicide (RID; Py-PB) and a permethrin pediculicide (NIX; PM). A total of 160 patients were evaluable for nit-combing speed, 156 patients were evaluable for efficacy at day 7, and 150 patients were evaluable for efficacy at day 14. Both Py-PB and PM showed 100% efficacy at day 7. At day 14, one patient in the PM group had an apparent reinfestation. The Py-PB group had significantly lower mean combing times (P=0.04), but because the PM group had more nits, the two groups were not significantly different in combing speed expressed as seconds per nit. Multiple regression and covariance analyses suggested that the greater speed of the Py-PB comb might have been masked by this baseline difference. Three patients had mild adverse experiences (Py-PB: erythema, PM: erythema and tingling sensation). No patients were removed from the study because of adverse events. In conclusion, this controlled clinical study demonstrated that both Py-PB and PM provided 100% efficacy following a single application. Differences attributable to comb design favored the Py-PB "rake" comb, but this requires additional evaluation and confirmation.

Effects of therapy with recombinant human growth hormone on insulin-like growth factor system components and serum levels of biochemical markers of bone formation in children after severe burn injury

Burn injury in children is associated with low bone formation and long-term bone loss. Because recombinant human GH (rHGH) may accelerate burn wound healing, and because rHGH increases bone formation and density in GH-deficient patients, we studied the short-term effects of rHGH on bone fomation, reflected by osteocalcin and type I procollagen propeptide levels in a randomized, double-blind, placebo-controlled study. Nineteen patients were enrolled and received either rHGH (0.2 mg/kg.day) or an equal volume of saline. Mean burn size and age were not different between the groups, and test substances were given from admission to time of wound healing (mean: 43 +/- 22 days). At wound healing, serum levels of insulin-like growth factor (IGF)-1 and IGF binding protein (IGFBP)-3 in the rHGH group rose to mean values of 229% and 187% of the respective means of the placebo group (P < 0.025). Serum osteocalcin concentrations remained below normal in both groups, and type I procollagen propeptide levels achieved a low normal level IGFBR-4 levels were twice that of normal on admission and doubled further at wound healing; IGFBP-5 levels were low on admission but rose to normal at wound healing. We conclude that large doses of rHGH were ineffective in improving disordered bone formation despite increasing serum IGF-1 and IGFBP-3. The rHGH-independent rise in serum levels of the inhibitory binding protein IGFBP-4 suggests a mechanism by which improved bone formation is prevented despite successful elevation of IGF-1 and IGFBP-3 in the burned child.

Nutrition and health for older persons in rural America: a managed care model

Health care services and resources for older persons living in rural areas may be highly variable, and integrated service-delivery models are often lacking. This article presents a managed-care model of nutrition risk screening and intervention for older persons in rural areas. Nutrition risk screening was implemented by the Geisinger Health Care System, Danville, Pa, to target all eligible enrollees in a regional Medicare risk program. A single remote clinic site participating in the managed health care system was chosen for further study of a linked screening and case-management effort for undernourished persons. Screening and intervention at the clinic site selected for this study were guided by centralized expertise and resources. Individualized evaluation and intervention plans were developed with the aid of a dietitian and implemented by the clinic case manager. Of the 417 subjects who completed screening at the remote site, 68 met the risk criteria for undernutrition and were selected for case management. Many of the targeted persons received interventions that included evaluations by a physician or physician extender (eg, physician assistant, nurse practitioner) at the clinic and consultations with nutrition, mental health, or social services professionals. Twenty-six of the subjects who took part in the intervention completed a follow-up screening 6 months later. Ten of those persons no longer exhibited risk criteria. This demonstrates the feasibility of a linked screening and case management program for nutrition risk in the managed-care setting.

Dysregulation of calcium homeostasis after severe burn injury in children: possible role of magnesium depletion

OBJECTIVE

To determine the cause and extent of hypocalcemia observed in children after severe burns.

DESIGN

We studied 10 children with burns covering 57% +/- 17% (SD) body surface area, ages 9.6 +/- 4.7 years, who were admitted consecutively during a 6-month period. Diet supplied a minimum of 2.7 gm/m2 of calcium, 0.3 gm/m2 of magnesium, and 2.2 gm/m2 phosphate. Blood specimens were obtained daily for 10 +/- 5 days for the following tests: (1) simultaneous analysis for ionized calcium, magnesium, and intact parathyroid hormone (group A); (2) two of these children, randomly selected, had serial 2-hour determinations on a single day (group B); (3) a modified Ellsworth-Howard test, consisting of a 10-minute infusion of synthetic parathyroid hormone 18 +/- 10 days post-burn and associated changes in urinary cyclic adenosine monophosphate excretion and renal threshold phosphate concentration (group C). Three of these children, when normomagnesemic, also received a standard magnesium infusion to determine magnesium retention (group D). Data were analyzed with chi-square, regression analysis, and non-parametric testing as appropriate.

RESULTS

All patients showed sustained hypocalcemia and hypomagnesemia; intact parathyroid hormone response was inappropriately low and response to synthetic parathyroid hormone infusion was blunted. Lowest ionized calcium levels were associated with hypomagnesemia.

CONCLUSION

Hypoparathyroidism and blunted renal response to parathyroid hormone suggest that magnesium depletion may contribute to their pathogenesis. Magnesium repletion and monitoring are recommended.

Burn-associated bone disease in sheep: roles of immobilization and endogenous corticosteroids

To determine the role of immobilization in the pathogenesis of burn-associated bone disease, we selected the sheep as a model to study the effects of burn injury compared with a sham-burned control group. Seven of the sheep were subjected to controlled 40% flame burn, and seven underwent anesthesia with arterial and venous cannulation but without burn. After labeling newly formed bone with tetracycline and calcein, the sheep were killed 2 weeks after burn or sham burn, and the iliac crest and lumbar vertebrae were analyzed for histomorphometry. Analysis failed to demonstrate a significant reduction of bone formation rate in the burned sheep. Osteoid area and surface and osteoblast surface, which correlated significantly with bone formation rate (r = 0.49, p < 0.025), were reduced in the burned sheep. Results suggest that immobilization may play a primary role in the pathogenesis of burn-associated bone disease, but the presence of differences in other histomorphometric features indicates the bone disease is multifactorial.

Brompheniramine, terfenadine, and placebo in allergic rhinitis

BACKGROUND

Second-generation antihistamines, reported to lack central nervous system depressant activity, may be considered to have a clinical advantage over traditional antihistamines.

OBJECTIVE

To compare the effectiveness, at recommended doses, of an extended-release formulation of nonprescription brompheniramine and prescription terfenadine in the treatment of allergic rhinitis.

METHODS

This was a double-blind, randomized, placebo-controlled, multicenter, parallel study. Subjects with symptoms of allergic rhinitis received brompheniramine 12 mg (n = 96), terfenadine 60 mg (n = 96), or placebo (n = 95) twice daily for 14 days. Subjects returned on treatment days 3, 7, and 14; at which times, the investigator assessed symptom severity (i.e., rhinorrhea; sneezing; nasal blockage; pruritus of the eyes, nose, or pharynx; watery eyes; and postnasal drip). The investigator and the subject each completed a global efficacy evaluation, and subjects were interviewed regarding the occurrence of adverse experiences. Symptoms were analyzed as summed severity scores for (1) all symptoms and (2) for the symptom cluster of rhinorrhea, sneezing, and nasal blockage.

RESULTS

At all post-baseline evaluations (days 3, 7, and 14), brompheniramine was significantly better (P < or = .05) than terfenadine and placebo for both sets of summed symptom scores and for both global assessments. Terfenadine was significantly better (P < or = .05) than placebo on the physician's global at day 14. Central nervous system-related complaints were the most frequently reported adverse experiences among all three groups; somnolence was reported most frequently by brompheniramine-treated subjects.

CONCLUSION

A nonprescription, extended-release formulation of brompheniramine, 12 mg bid, provided significantly better relief of symptomatic allergic rhinitis than terfenadine, 60 mg bid.

Histomorphometric and biochemical characterization of bone following acute severe burns in children

Severe burns in adults is associated with an uncoupling of normal remodeling, low bone formation without reduced resorption. The risk of osteopenia that may occur under such circumstances is heightened by our detection in a cross-sectional study of low bone mass in severely burned children. We report here the acute histomorphometric and biochemical response of bone to severe burn injury, as well as bone mass in severely burned children. We enrolled 24 patients ages 5.8 to 17.5 years following burns of 63 +/- 16% (SD) body surface area. Serum and urine were collected weekly until iliac crest bone biopsy was obtained 26 +/- 10 days postburn. Seventeen of 18 patients, including 5 patients receiving growth hormone treatment to accelerate wound healing, failed to take up doxycycline in trabecular bone, and had no detectable osteoblasts at the osteoid seam, while eroded surface was normal and osteoblasts were documented by staining. Thus, bone formation was virtually absent. There was an eightfold elevation in urinary free cortisol excretion and high serum levels of acute phase reactants and interleukin-1 beta and -6. Biochemical markers of bone formation, osteocalcin, and type I procollagen propeptide were low, as were resorptive markers urinary pyridinoline and deoxypyridinoline. However, there was no correlation with resorptive surface. Mean age-related z-score for bone mass was -1.06 +/- 1.05, 40 days postburn. Immobilization and endogenous corticosteroid production may be the main factors responsible for acutely reduced bone formation while inflammatory cytokines may mediate resorption.

Cetirizine and astemizole therapy for chronic idiopathic urticaria: a double-blind, placebo-controlled, comparative trial

BACKGROUND

Cetirizine and astemizole have been shown to be safe and effective in the treatment of patients with chronic idiopathic urticaria. Cetirizine brings about clinical benefit more rapidly.

OBJECTIVE

The purpose of this study was to compare the efficacy of single daily doses of cetirizine and astemizole in relieving the symptoms of chronic idiopathic urticaria, with particular emphasis on the commencement of action.

METHODS

Patients with chronic idiopathic urticaria were randomly assigned to relieve either 10 mg of cetirizine, 10 mg of astemizole, or placebo for 4 weeks in a multicenter double-blind trial. Patients rated symptom severity each night, and investigators rated symptoms weekly.

RESULTS

One hundred eighty-seven patients were enrolled in the trial; 180 were included in the safety analysis and 177 were included in at least one efficacy analysis. Both cetirizine and astemizole were significantly superior to placebo in relieving symptoms of chronic idiopathic urticaria. Both patients' and investigators' ratings indicated that cetirizine acted more rapidly. Both active treatments were well tolerated, and the incidence of somnolence did not differ statistically between cetirizine (14.5%) and astemizole (10.3%).

CONCLUSION

Both cetirizine and astemizole provide effective relief of the symptoms of chronic idiopathic urticaria with similar side-effect profiles. However, clinical benefit occurs significantly more rapidly with cetirizine.

Aluminum in parenteral solutions revisited--again

It has been a dozen years since aluminum was first shown to contaminate parenteral nutrition solutions and to be a contributing factor in the pathogenesis of metabolic bone disease in parenteral nutrition patients as well as in uremic patients. However, there are no regulations in place to effectively reduce aluminum contamination of various parenterally administered nutrients, drugs, and biologic products. The purpose of this review is fourfold: 1) to summarize our knowledge of the adverse effects of aluminum on bone formation and mineralization in parenteral nutrition patients; 2) to discuss the possible role of aluminum in the osteopenic bone disease of preterm infants; 3) to show how lack of regulations covering aluminum content of parenteral solutions can lead to vulnerability of new groups of patients to aluminum toxicity, the example being given here is that of burn patients; and 4) to trace the development of efforts at regulating the aluminum contamination of large- and small-volume parenteral drug products and to point out what still needs to be done in this regard.

Rat tail suspension reduces messenger RNA level for growth factors and osteopontin and decreases the osteoblastic differentiation of bone marrow stromal cells

We previously reported that bone marrow stromal cells produce insulin-like growth factors (IGF-I and -II), and that medium conditioned by marrow stromal cells stimulates osteoblast proliferation in vitro. The present study employed the rat tail-suspension model to unload the hindlimbs. It was designed to test the hypothesis that the development of osteopenia or osteoporosis could be due to a deficit in the osteogenic function of marrow stromal cells. Although tail suspension suppressed body weight during the first 3 days of an 11-day pair-fed study, the overall weight gain recorded by these animals was normal. Nevertheless, bone growth was inhibited by suspension. Similarly, the total adherent marrow stromal cell population harvested from the femurs and tibias was decreased by tail suspension, and only half the normal number of fibroblastic stromal cell colonies grew when they were cultured. The proliferation of alkaline-phosphatase-positive cells in the stroma was also inhibited. Northern hybridization revealed that the messenger RNA level for transforming growth factor-beta 2 and IGF-II in stromal cell was reduced by tail suspension. The production of IGF-II by marrow stromal cells was also decreased. The steady-state level of five different transcript sizes of IGF-I mRNA was altered differentially by tail suspension. Osteopontin mRNA was also reduced in marrow stromal cells from tail-suspended rats compared with the normal rats. These data suggest that skeletal unloading not only alters the mRNA level for growth factors and peptide production, but also affects the proliferation and osteogenic differentiation of marrow stromal cells. These changes may be responsible for the reduced bone formation in osteopenia and osteoporosis.

Long-term reduction in bone mass after severe burn injury in children

OBJECTIVE

Because burn victims are at risk of having bone loss, a cross-sectional study was undertaken to determine whether severe burn injury had acute and long-term effects on bone mass or on the incidence of fractures in children.

METHODS

Dual-energy x-ray absorptiometry of the lumbar portion of the spine was performed on 68 children: 16 moderately burned (15% to 36% of total body surface area) and 52 age-matched severely burned (> or = 40% of total body surface area). Twenty-two severely burned children were hospitalized and studied within 8 weeks of their burn, and 30 others were studied approximately 5 years after discharge. In the severely burned group, both hospitalized and discharged, serum and urine were analyzed for calcium, phosphorus, intact parathyroid hormone, osteocalcin, and type I collagen telopeptide.

RESULTS

Sixty percent of severely burned patients had age-related z scores for bone density less than -1, and 27% of severely burned patients had age-related z scores for bone density less than -2 (p < 0.005, for each). In the moderately burned group, 31% of patients had z scores less than -1 (p < 0.005 vs normal distribution), but only 6% had z scores less than -2 (p value not significant). There was evidence of increased incidence of fractures after discharge in the severely burned patients. Biochemical studies were compatible with a reduction in bone formation and an increase in resorption initially, and with a long-term persistence of low formation.

CONCLUSION

We conclude that acute burn injury leads to profound and long-term bone loss, which may adversely affect peak bone mass accumulation.

Management of hymenoptera sting anaphylaxis: a preventive medicine survey

The evaluation of aftercare instructions given to patients suffering from hymenoptera sting anaphylaxis was the objective of the study. Part of this evaluation included asking the physicians questions to examine the knowledge on which they based their aftercare instructions. Survey questionnaires were completed by 124 of 174 (71%) physicians who worked in an emergency department or urgent care center. Fifty-eight percent of the physicians never provided written avoidance instructions, 24% provided or prescribed anaphylaxis ID bracelets, 44% referred all of their patients to an allergist for further evaluation, and 73% reported prescribing an Epi-pen or Ana-kit to all hymenoptera sting anaphylaxis victims. Twenty-four percent of physicians did not know where to obtain anaphylaxis identification bracelets. This survey demonstrates that a substantial number of physicians practicing emergency medicine are not providing appropriate aftercare instructions to patients, and substantiates the need for educational efforts to increase the awareness of physicians concerning the implications of hymenoptera allergy and the value of proper preventive measures.

Risk of aluminum accumulation in patients with burns and ways to reduce it

Severely burned patients experience a bone lesion consisting of markedly reduced bone formation and evidence of decreased resportion. The cause of the lesion may be multifactorial, but aluminum loading, which also occurs in patients with burns, has been documented to produce this type of injury in both humans and animals. To assess the risk of aluminum loading with patients with burns, we analyzed fluids, creams, and medication used in the management of acute burn injury for aluminum content. These substances were classified according to route of administration: cutaneous, enteral, or parenteral, to assess the risk of aluminum loading. Cutaneous exposure to aluminum is greatest from baths, which may provide up to 8 mg aluminum. However, the dynamics of aluminum entry into the blood via a damaged skin barrier are unclear. Enteral exposure to aluminum is no greater than daily dietary exposure. Parenteral sources of aluminum, especially 25% human serum albumin and calcium gluconate, provide the most significant risk of loading because of direct introduction of aluminum into the circulation. Substitution with a different brand of albumin and calcium chloride can reduce the parenteral aluminum load by as much as 95% and minimize any role aluminum may play in the pathogenesis of this bone lesion.

Total parenteral nutrition and its effects on bone metabolism

Total parenteral nutrition (TPN) may affect bone metabolism in a variety of ways. These may include potential indirect effects such as on gastrointestinal hormone secretion, liver function, especially cytochrome P450 isoenzymes, metabolic biorhythms where established, and the continuous compared with the intermittent supply of nutrients. More substantial evidence exists for the reduction of bone formation, parathyroid hormone secretion, and calcitriol production in TPN patients along with high urinary calcium excretion. This review considers both aluminum loading and vitamin D sensitivity as etiologic factors and suggests that aluminum may have played a primary role in the pathogenesis of these abnormalities in bone and mineral metabolism, but that vitamin D may have potentiated the deleterious actions of aluminum. While the sources of aluminum contamination of TPN solutions have been identified and efforts are under way to reduce its contamination of TPN solutions, the persistence of low bone mass measurement in TPN patients is a problem that has been identified repeatedly, does not have a current explanation, and requires further study.

Effects of aluminum on rat bone cell populations

Aluminum (Al) loading is associated with reduced bone formation and osteomalacia in human and certain animal models. However, uncertainty exists as to the cellular effect(s) of Al as both inhibition and stimulation of osteoblast proliferation have been reported. Furthermore, the extent to which Al affects osteoprogenitor cell populations is unknown. To determine the cellular effects of Al in the rat, an animal model in which Al bone disease has been produced, we compared the in vitro effect of 10-50 microns Al on the proliferation and hydroxyproline collagen formation of marrow osteoprogenitor stromal cell populations and perinatal rat calvarial osteoblasts. In subconfluent cultures, Al suppressed proliferation of both marrow fibroblast-like stromal cells and calvarial osteoblasts. In confluent cultures, however, Al selectively stimulated periosteal fibroblast and osteoblast DNA synthesis and collagen (hydroxyproline) production, both in the presence or absence of 1,25-dihydroxyvitamin D. Osteocalcin was not detected in osteoblast-conditioned media or extracellular matrix. These observations suggest that the bone formation defect associated with Al toxicity in growing rats may be a function of impaired patterns of osteoprogenitor/osteoblast proliferation. Furthermore, the Al-stimulated increase in collagen formation is consistent with the development of osteomalacia in Al-toxic humans and animals. The mechanism by which Al stimulated DNA synthesis and collagen production in more mature cultures awaits further study.

Rat tail suspension causes a decline in insulin receptors

Decreased muscular activity results in weakness and muscular atrophy. Coincident with this protein catabolic state is glucose intolerance and hyperinsulinemia. Rats were tail suspended for 7 to 14 days to accomplish unloading of the hindlimbs. Insulin resistance was documented in these animals by a 14 day tail suspension-related 26% increase in serum glucose in spite of a 253% increase in serum insulin concentration. Microsomal membranes were prepared from hindlimb muscles and specific binding of insulin and insulin-like growth factor I (IGF-I) were determined in these membranes. Insulin binding was decreased by 27% at 7 days and by 21% at 14 days. In contrast, IGF-I binding was unchanged at 7 days and was increased by 24% at 14 days. Liver membrane insulin receptors also had declined by 14 days of suspension, suggesting that the change in insulin receptors was a generalized, humorally-mediated phenomenon. These data suggest that tail suspension in rats results in insulin resistance, hyperinsulinemia, a decline in insulin receptors in liver and muscle, and a relative increase in muscle membrane IGF-I receptors. These data are consistent with the hypothesis that resistance to insulin's effects on protein metabolism in skeletal muscle may contribute to the protein catabolism associated with decreased muscular activity.

Nutritional rickets: thoughts about pathogenesis

The pathogenesis of nutritional rickets is not well-understood. While the etiologies include deficiencies of vitamin D, calcium (Ca) or phosphate (PO4), and perhaps aluminium toxicity, the role these nutrients play in the development of tissue level anomalies characteristic of rachitic cartilage and bone has yet to be defined. Reported alterations in the biochemistry of rachitic bone and cartilaginous matrix which could adversely affect mineralization and endochondral ossification are of questionable significance since the tissues mineralize rapidly when exposed to Ca and PO4 salts in vivo and in vitro. The low Ca and PO4 concentrations of the extracellular fluid (ECF) bathing rachitic cartilage and bone matrix suggest that local mechanisms operate to impair mineralization. In healing rickets, the Ca and PO4 content of these tissue fluids increases in the same time-frame it takes to experimentally remineralize the matrices. However, it is not certain what determines the Ca and PO4 content of the ECF. Cytokines which may play a role in the cellular regulation of Ca and PO4 and maintain processes which contribute to normal patterns of endochondral ossification could provide a mechanism common to the pathogenesis of rickets from a variety of causes.

Increased biliary transferrin excretion following parenteral aluminium administration to rats

Aluminium accumulates in the livers of patients receiving either parenteral nutrition or haemodialysis. When given parenterally to rats, aluminium causes cholestasis. However, the mechanism of hepatic aluminium uptake and the fate of aluminum in the liver are poorly understood. We examined the effect of parenteral aluminium administration on biliary excretion of transferrin, the major circulating aluminum-binding protein. Male Wistar rats were given parenterally aluminum 5 mg/kg/day for 1-14 days. Bile was collected for 3 hr at the end of the study period. Biliary total protein concentration and IgA/total protein were unaffected by up to 14 days of parenteral aluminium administration. However, biliary transferrin excretion increased with duration of aluminum administration up to five-fold by day 14. Biliary transferrin concentration and transferrin/total protein was higher in aluminum treated rats than controls after 7 and 14 days of study. Hepatic aluminum concentration reached a maximum after 4 days of parenteral aluminum administration, at which time serum bile acid and alanine amino transferase values were not different from controls. Since biliary transferrin is normally derived from the serum, it is likely that aluminum promotes hepatocellular uptake of transferrin and that aluminum enters the hepatocyte bound to transferrin. We postulate that transferrin may direct aluminum to intracellular sites where its toxic effects would be minimized.

Bone disease in burn patients

Burn patients are at risk for bone disease due to aluminum (Al) exposure from use of antacids and albumin, partial immobilization, and increased production of endogenous glucocorticoids. Moreover, severely burned children are growth impaired up to 3 years after the burn. To determine the extent of bone disease, we studied nine men and three women, ages 18-41 years, with greater than 50% body surface area burn. Seven patients underwent iliac crest bone biopsy following double tetracycline labeling, one additional patient expired after a single label, and three others had postmortem specimens obtained for quantitative Al only. Serial serum and urine samples were obtained weekly until biopsy or death. All biopsied patients had reduced bone formation and osteoid area, surface, and width, with mineral apposition rate, osteoblast surface, and osteoclast number with normal eroded surfaces compared to age- and sex-matched normal ambulatory volunteers. Burn patients also had reduced bone formation, mineral apposition rate, osteoid area, and surface compared to age-matched volunteers at short-term bed rest. Serum levels of osteocalcin were low. Most patients had mild hypercalcemia but only a third had hypercalciuria. All patients had elevated Al in blood or urine; urine Al correlated inversely with serum osteocalcin. In 60% significant bone Al was detectable by stain or quantitation. Our data are compatible with burn patients having markedly reduced bone turnover. Al loading, partial immobilization, endogenous corticosteroids, and cytokine production may be among the etiologic factors.

Controlling allergies by controlling environment. A big help for your patients

Control of the environment is a cost-effective method of limiting allergic reactions in susceptible people. For physicians working with allergic patients, this approach involves guiding the patient and family in ridding their home and surroundings of allergens and irritants. Dr. Klein discusses the environmental-control protocol, particularly in regard to dust mites, mold, pollen, and pets.