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Chromium is an essential trace element involved in the metabolism of carbohydrates, lipids, and proteins mainly by increasing the efficiency of insulin. Chromium deficiency affects the maintenance of normal glucose tolerance and healthy lipid profiles. The Estimated Safe and Adequate Daily Dietary Intake for chromium is 50 to 200 microg/d for adults. However, the dietary intake of chromium in humans is often suboptimal. Chromium assessment has proven to be a challenge due to the low amounts of chromium present in biological materials and the absence of a reliable indicator of chromium status. Recently, chromium has been touted as an agent for increasing lean body mass and decreasing percent body fat. This article reviews the various studies that have been conducted to investigate the relationship of chromium with exercise and body composition.

During the last 3 decades, remarkable advances have taken place in the field of zinc metabolism. Thirty years ago, only three enzymes that required zinc for their activities were identified; today more than 200 such enzymes have been classified. Zinc plays a vital role in human nutrition and biochemical function. Prior to 1963, zinc deficiency in humans was unknown. Today, it is recognized that a nutritional deficiency of zinc is common throughout the world, including the U.S.A marginal deficiency of zinc appears to be prevalent in many segments of populations in developed countries, and more severe deficiencies are widespread in many parts of the world. Therefore, it is important that proper steps to correct zinc deficiency are taken. However, the assessment of zinc nutriture has always proven to be a difficult problem because no reliable measure of zinc status currently exists. More recently, it has been recognized that zinc may play an important role in thyroid hormone metabolism, although the exact mechanism by which zinc affects thyroid hormone function is far from clear. In addition, exercise has been shown to alter zinc status. This review will focus on the relationship among zinc status, exercise, and thyroid hormone function.

Iron plays an important role, not only in oxygen delivery to the tissues, but also as a cofactor with several enzymes involved in energy metabolism and thermoregulation. As a result, much research has been dedicated to understanding the ramifications of iron depletion and iron deficiency anemia on the physiological functions of these enzymes. There is evidence to suggest that iron depletion and iron deficiency anemia cause physiological changes in the body not only during exercise, but also under resting conditions. Both rat and human studies have produced results revealing elevated levels of norepinephrine in the blood and urine of iron-deficient anemic subjects. These studies also provide evidence to suggest that elevation in metabolic rate may ultimately lead to slower growth rates and lower body weights in iron-deficient anemic animals and humans. The focus of this review is on the effects of iron deficiency on metabolic rate and thermoregulation. Prior to this discussion, a brief background on iron is presented.

The Authors report a case of an incidentally discovered mandibular cyst in a 40-year-old man. X-ray examination revealed an intramandibular symmetric radiolucency extending from the right II molar to the left II one; it was not connected to the root apices of residual teeth, but contained three sopranumerary tooth buds in incisive area. Histology showed a cyst lined-up by stratified squamous epithelium, with focal orthokeratinization. The clinico-radiographic and histologic findings were consistent with a median mandibular cyst, unusually large; the presence of medially located denticles inside the cyst strongly suggested an odontogenic origin.

The effects of preexercise feeding on responses to endurance exercise and performance were investigated. Untrained adolescent boys (N = 13, age 14.9 +/- 0.5 years) completed three endurance test sessions separated by a minimum of 72 hr. Each session consisted of 75 min of cycling at 60% of VO2 max followed by a high-intensity performance test. Dietary conditions were a candy bar (C1: 280 kcal, 36 g CHO), fat-free fig bars (C2: 200 kcal, 44 g CHO), and a nonnutritive sweetened drink (C3: placebo), ingested 10 min prior to exercise. Respiratory gases, heart rate, blood glucose, and lactate concentrations were measured throughout the test. ANOVA results revealed significant time effects for all variables; however, no differences were seen among the conditions. Performance times, 311.9 +/- 38.5 s in C1, 316.2 +/- 37.3 s in C2, and 328.1 +/- 46.4 s in C3, were not significantly different among conditions. Thus, preexercise feeding did not affect responses to endurance exercise or performance in adolescent boys.

It has been reported that boron may be beneficial for optimal calcium metabolism and, thus, optimal bone metabolism. Therefore, we designed a study to determine the effects of boron supplementation on blood and urinary minerals in athletic subjects and sedentary control subjects consuming self-selected typical Western diets. Serum phosphorus concentrations were lower in boron-supplemented subjects than in placebo-supplemented subjects. Compared with all other subjects, serum magnesium concentrations were greatest in the sedentary control subjects supplemented with boron and increased with time in all subjects. Exercise training diminished changes in serum phosphorus concentrations caused by boron supplementation. Calcium excretion increased over time in all groups combined, and boron excretion increased over time in all boron-supplemented subjects. The findings suggest that boron supplementation modestly affected mineral status, and exercise modified the effects of boron supplementation on serum minerals.

The effects of boron supplementation on blood and urinary minerals were studied in female college students--17 athletes and 11 sedentary controls--over a one-year period. The athletes had lower percent body fat and higher aerobic capacities than sedentary controls. Athletic subjects consumed more boron in their normal diets than sedentary subjects; all other dietary measures were similar between the two groups. The athletes showed a slight increase in bone mineral density, whereas the sedentary group showed a slight decrease. Serum phosphorus concentrations were lower in boron-supplemented subjects than in subjects receiving placebos, and were lower at the end of the study period than during baseline analysis. Activity depressed changes in serum phosphorus in boron-supplemented subjects. Serum magnesium concentrations were greatest in the sedentary controls whose diets were supplemented with boron, and increased with time in all subjects. A group x supplement interaction was observed with serum magnesium; exercise in boron-supplemented subjects lowered serum magnesium. In all subjects, calcium excretion increased over time; in boron-supplemented subjects, boron excretion increased over time. In all subjects, boron supplementation affected serum phosphorus and magnesium, and the excretion of urinary boron.

Osteoporosis is a disease that characteristically afflicts postmenopausal women. It is estimated that millions of people are plagued yearly with this debilitating disease. Associated health care costs are in the billions of dollars, annually. Much research has been conducted in the area of osteoporosis and mineral supplementation, mainly focusing on calcium and vitamin D. Nonetheless, more recent studies have reported possible improvements in bone mineral density in women who were supplemented with the ultratrace mineral, boron. Boron may play a role in bone metabolism, but its role is most likely to be associated with its interactions with other minerals and vitamins such as calcium, magnesium and vitamin D. Although the focus of this review will be to discuss the interactive role of boron with magnesium and bone metabolism, some discussion of its interactive role with vitamin D is also necessary.

Antibody responses to 23-valent pneumococcal vaccine were studied in 38 individuals infected with human immunodeficiency virus (HIV), including 6 with asymptomatic infection, 24 with AIDS or AIDS-related complex (ARC) receiving treatment with zidovudine, and 8 untreated AIDS/ARC patients. Antibody responses were significantly higher for asymptomatic persons (aggregate geometric mean, 972 ng of antibody nitrogen (AbN)/ml; P less than .001) and AIDS/ARC patients receiving a median of 12 weeks (range, 4-54) of zidovudine therapy (mean, 369 ng of AbN/ml; P less than .001) when compared with untreated AIDS/ARC patients. Antibody responses among zidovudine-treated AIDS/ARC patients were independent of the dose (mean, 629.2 mg/day; range, 100-1200 mg) or duration of zidovudine therapy. For zidovudine-treated AIDS/ARC patients, persistence of an aggregate antibody response 8 months after vaccination was associated with survival at 14 months after vaccination, whereas waning of response was not. Pneumococcal vaccine should be administered as early as possible in the course of HIV infection. Immunization should be delayed for at least 4 weeks for AIDS/ARC patients initiating zidovudine therapy.

Several surveys of ethrane pollution were made by the authors in operating rooms, either equipped or not with general ventilation systems, during operations where non-rebreathing anaesthesia devices were used. In operating rooms without general ventilation systems, but with simple air conditioning systems, ethrane pollution was found to be rather high and to attain 30-40 ppm at the fourth hour of operation. No statistically significant differences were elicited among levels found at the anaesthetist, surgeon and assistance personnel sites. The authors analyze the kinetics of ethrane pollution as a function of its consumption and of time and discuss the most suitable means for decreasig and preventing such pollution.

Controversy exists concerning the degree of importance of periventricular intraparenchymal echodensities (IPE) observed on neonatal ultrasound scans in the determination of subsequent neurologic disability in premature infants. In this report, IPE was studied in 75 infants weighing less than 2,000 g at birth to determine the basic characteristics of the lesion, the likely pathogenesis, the outcome, and the aspects of the ultrasonographic appearance in the acute period of neonatal illness that are important for prediction of outcome. IPE was defined as any periventricular echodensity greater than 1 cm in at least one dimension. IPE was strikingly associated with large areas of intraventricular hemorrhage (IVH) (81% of cases). IPE was distinctly asymmetric. Thus, the lesion was either exclusively unilateral (67%) or bilateral with marked predominance on one side. The associated IVH was asymmetric in approximately 80% of cases, and in all 50 cases of large asymmetric IVH, IPE occurred on the same side as the larger amount of intraventricular blood. Moreover, more than 50% of such cases of IPE associated with large asymmetric IVH were progressive. Neuropathologic correlation showed that IPE represented hemorrhagic necrosis of periventricular tissue. Concerning pathogenesis, these data raise the possibility that large asymmetric IVH is related etiologically to IPE. Outcome varied with the severity of the IPE. Thus, the mortality rate among the 38 infants with extensive IPE was 79%. Of the survivors with extensive IPE, all had subsequent major motor deficits and all but one exhibited cognitive function less than 80% of normal. Among the 37 infants with localized IPE, the mortality rate was 38%. Of the survivors, although 79% had major motor deficits, 43% had cognitive function greater than 80% of normal. Thus, the findings demonstrate that with extensive IPE there is little or no chance for survival with normal neurologic and cognitive outcome, but with localized IPE, although major motor deficits are common, an appreciable proportion of infants have cognitive function in the normal range. Careful, quantitative assessment of the ultrasonographic features of IPE in the acute period of illness in the premature infant is of major value in estimating outcome.

Despite major changes in the epidemiology, microbiology, and prognosis over the last 50 years, the diagnosis of infective endocarditis is still difficult, and serious complications including death are not uncommon. Prosthetic and right-sided valvular infections are more common and require longer periods of vigorous antimicrobial therapy than in the past. An effective short-course antibiotic regimen has been designed for sensitive microorganisms, and protocols have been established for culture-negative cases (15 percent) and empiric situations. Finally, cardiac surgery should be considered as an important modality, especially in cases of congestive heart failure.

Measurements of regional cerebral blood flow (CBF) with positron emission tomography in adult humans with cerebrovascular disease have demonstrated consistently that values below 10 ml/(100 gm.min) occur only in infarcted brain. Although experimental data suggest that the newborn brain may be more resistant to ischemic injury than the adult brain, the minimum CBF necessary to sustain neuronal viability in newborn infants is unknown. We have measured CBF with positron emission tomography in 16 preterm and 14 term newborn infants and have determined the relationship between CBF and subsequent brain function as assessed by neurological examination and developmental assessment. The range of mean CBF in the preterm infants was 4.9 to 23 ml/(100 gm.min) and the range of mean CBF in the term infants was 9.0 to 73 ml/(100 gm.min). Five preterm infants and one term infant with mean CBF less than 10 ml/(100 gm.min) survived. Three of these 5 preterm infants, with mean CBF of 4.9, 5.2, and 9.3 ml/(100 gm.min), respectively, have normal neurological examinations and Bayley Scales of 80 or greater at 6, 6, and 24 months of age, respectively. One (mean CBF 6.9) has normal cognitive development (Bayley 103) and a mild spastic diplegia at age 19 months, and one infant (mean CBF 6.2) has a left hemiparesis and a Binet IQ score of 70 at age 33 months. The term infant, with a mean CBF of 9.0 ml/(100 gm.min), was developing normally when he died of sepsis at age 5 months.(ABSTRACT TRUNCATED AT 250 WORDS)