Salt sensitivity and systemic hypertension in the elderly

Aging in industrialized societies is accompanied by increases in the incidence and prevalence of hypertension, with a disproportionately greater increase occurring among aging blacks than among aging whites. This geriatric hypertension is generally of a salt-sensitive nature with a disproportionate frequency of isolated systolic hypertension. Although salt-taste acuity declines with age, salt sensitivity among the elderly does not appear to result from a compensatory increase in salt intake. Rather, age-related increases in salt sensitivity result, in part, from a reduced ability to appropriately excrete a salt load, which is due to a decline in renal function and to a reduced generation of natriuretic substances such as prostagiandin E₂ and dopamine. Age-associated declines in the activity of membrane sodium/potassium-adenosine triphosphatase (Na/K-ATPase) may also contribute to geriatric hypertension because this results in increased intracellular sodium that may cause reduced sodium-calcium exchange and thereby increase intracellular calcium and vascular resistance. Reductions in cellular calcium efflux due to reduced calcium-ATPase activity may similarly cause an increase in intracellular calcium and vascular resistance. Increasing dietary calcium intake may represent an effective nonpharmacologic treatment for some salt-sensitive persons because it appears to reduce intracellular calcium by (1) suppressing parathyroid hormone-mediated calcium influx, (2) increasing Na/K-ATPase activity, and (3) reducing intravascular volume due to calcium-induced natriuresis.     

Ulnar neuropathy with and without elbow instability

Increased valgus stresses on the medial aspect of the elbow can result in a number of bony and soft-tissue abnormalities. The most common abnormalities are ulnar neuropathy and valgus instability secondary to injury of the medial collateral ligament. Diagnosis and treatment of these disorders are discussed in this article.     

Corrosion of orthodontic brackets: qualitative and quantitative surface analysis

ObjectivesTo determine and compare surface characteristics and presence of corrosion in new and used brackets with optical light microscopy (OLM) and scanning electron microscopy (SEM), and with elemental chemical analysis with energy-dispersive X-ray spectroscopy (EDS).Materials and MethodsOLM and SEM were used to analyze 24 new and 24 used conventional premolar brackets. EDS analysis was performed in six used brackets and four new brackets with corrosion-suspected spots.ResultsOLM and SEM images showed wear/abfraction signs, striations, pits/crevices, and adherent material. Used brackets showed more deterioration than new brackets. SEM images disclosed more morphological features than OLM images. EDS analysis revealed a significantly higher phosphorus (P = .001) and sodium (P < .005) weight fraction and significantly lower amounts of chromium (P < .001) in used brackets. The iron, chromium, and nickel weight fractions did not differ significantly between the clean and corrosion-suspected spots. Of the corrosion-suspected spots analyzed by combined SEM and EDS, 44.14% and 6.90% remained corrosion-suspected on used and new brackets, respectively.ConclusionsUsed brackets showed more signs of corrosion than new ones. Combined assessment of SEM and EDS indicates that the bracket surface is affected during orthodontic treatment as a result of corrosion.     

Body composition and metabolic factors in obese children and adolescents

OBJECTIVE: Body composition is associated with metablic factors in adults; however, data are limited regarding obese children. This study was undertaken to assess body composition, regional fat distribution, and metabolic factors in obese 6-18-y-old children and adolescents. DESIGN: Cross-sectional assessment. SUBJECTS: Thirty-six obese children and adolescents, (mean+/-s.e.m.) age 11.8+/-0.5 y, BMI 34.1+/-1.2 kg/m(2). MEASUREMENTS: Body composition was assessed by dual energy X-ray absorptiometry and computerized tomography. Fasting insulin, glucose and leptin levels, and the homeostasis model assessment of insulin sensitivity (HOMA-IR) were assessed. RESULTS: The girls had significantly lower glucose levels than the boys. The ethnic group differences (African American children vs white children) in fat mass, total CT fat, subcutaneous CT fat, insulin level, leptin level, and higher HOMA-IR were not significant after adjusting for age or pubertal stage. These differences in abdominal fat and subcutaneous abdominal fat were also not independent of total body fat or BMI. No ethnic group differences in visceral abdominal fat were noted. Insulin level and HOMA IR were associated with leptin level (independent of fat mass) and fat mass. Leptin level was associated with fat mass, total CT fat, and subcutaneous CT fat; however the associations between the CT fat measures and leptin were not independent of total body fat mass. CONCLUSIONS: Neither visceral abdominal fat, subcutaneous abdominal fat, insulin levels, or insulin resistance differed by ethnic group when adjusted for age or pubertal status. This contrasts with findings in adults and non-obese children which suggest lower levels of visceral fat and higher insulin levels and insulin resistance in African American children and adolescents.     

Type B hepatitis after needle-stick exposure: prevention with hepatitis B immune globulin. Final report of the Veterans Administration Cooperative Study.

Hepatitis B immune globulin (HBIG) and immune serum globulin (ISG) were examined in a randomized, double-blind trial to assess their relative efficacies in preventing type B hepatitis after needle-stick exposure to hepatitis B surface antigen (HBsAG)-positive donors. Clinical hepatitis developed in 1.4% of HBIG and in 5.9% of ISG recipients (P = 0.016), and seroconversion (anti-HBs) occurred in 5.6% and 20.7% of them respectively (P less than 0.001). Mild and transient side-effects were noted in 3.0% of ISG and in 3.2% of HBIG recipients. Available donor sera were examined for DNA polymerase (DNAP) and e antigen and antibody (HBeAg; anti-HBE). Both DNAP and HBeAg showed a highly statistically significant correlation with the infectivity of HBsAg-positive donors. Hepatitis B immune globulin remained significantly superior to ISG in preventing type B hepatitis even when the analysis was confined to these two high-risk subgroups. The efficacy of ISG in preventing type B hepatitis cannot be ascertained because a true placebo group was not included.     

The recognition and treatment of growth disorders – A 50-year retrospective

The past 50 years have seen great progress in the understanding and treatment of classic growth disorders. Advances such as the recognition of hormone receptor defects, the development of recombinant growth hormone, and the expanding awareness of epigenetic phenomena affecting growth are among these great achievements. Yet growth failure remains a pervasive problem among children with complex health conditions, such as survivors of childhood cancers, premature infants, organ transplant recipients, and children with cystic fibrosis. The significant increases in life expectancy among these groups underscores the potential consequences of poor growth, whether due to the underlying conditions or medical treatments, as they may have long-lasting effects into adulthood. The ongoing contributions of human biologists to the study of human growth remain essential in the recognition and treatment of growth disorders, by defining normal patterns of growth and body composition, the interplay of growth and maturation, the role of environmental, behavioral and genetic factors, and the long-term consequences of growth patterns. Examples will be given based on two common genetic disorders, cystic fibrosis and sickle-cell anemia, to highlight the relationships between growth failure, survival, and malnutrition. Also, a study of bone mineral accretion in children with cystic fibrosis will illustrate the importance of understanding patterns of growth in healthy children, and their application in the diagnosis and management of children with chronic disease. These examples accentuate the need for continued participation of human biologists in the study of growth and development and the care of children.