Effect of sorption and desorption resistance on aerobic trichloroethylene biodegradation in soils

Biodegradation of trichloroethylene (TCE) by toluene-degrading bacteria was measured under aerobic conditions in aqueous and soil-slurry batch microcosms. For soil-phase experiments, a freshly contaminated soil and a soil containing only the desorption-resistant fraction of TCE were tested. In both cases, presence of soil resulted in biodegradation rates substantially lower than those determined in the absence of soil. In aqueous-phase experiments, an appreciable increase in the rate and extent of TCE biodegradation was observed in microcosms when toluene was added multiple times. The TCE degradation rates were clearly correlated with toluene dioxygenase (TOD) enzyme activity over time, thus providing an indication of the cometabolic pathway employed by the microbial population. In soil-slurry experiments containing freshly contaminated soil, a TCE degradation rate of approximately 150 microg TCE/kg/h was observed during the first 39-h period, and then the TCE degradation rate slowed considerably to 0.59 and 0.84 microg TCE/kg/h for microcosms receiving one and two additions of toluene, respectively. The TCE degradation rates in soil-slurry microcosms containing the desorption-resistant fraction of TCE-contaminated soil were approximately 0.27 and 0.32 microg TCE/kg/h in microcosms receiving one and two additions of toluene, respectively. It is clear from these results that mass transfer into the aqueous phase limited bioavailability of TCE in the contaminated soil.     

Changing incidence of lobular carcinoma in situ of the breast

Estimating the incidence of lobular carcinoma in situ (LCIS) of the breast is challenging because it lacks both clinical and mammographic signs and is usually an incidental finding in breast biopsies performed for other reasons. In general, population-based studies are believed to provide the most accurate measures, but few documenting changes in LCIS incidence rates over time have been reported. Age-adjusted age-specific LCIS incidence rates among women with no prior history of in situ or invasive breast carcinoma from 1978 to 1998 were obtained from nine population-based cancer registries that participate in the Surveillance, Epidemiology, and End Results (SEER) Program. Linear trends were evaluated using negative binomial regression. Overall, LCIS incidence rates increased fourfold (95% confidence interval, 2.9–5.6) over the study period. Specifically, they rose from 0.90/100,000 person-years in 1978–80 to 2.83/100,000 person-years in 1987–89, but then increased only modestly up to 1996–98 where the incidence rate was 3.19/100,000 person-years. However, among women 50–79 years of age, LCIS incidence rates increased continuously over the study's duration. In 1996–98, 50–59 year-olds had the highest incidence rate (11.47/100,000 person-years) and experienced the greatest absolute increase in incidence over the study period (9.48/100,000 person-years). LCIS incidence rates have steadily increased from 1978 to 1998 only among postmenopausal women. Further research is required to assess what factors are contributing to these trends.     

The adolescents training and learning to avoid steroids program: preventing drug use and promoting health behaviors

BACKGROUND: Use of alcohol and other illicit drugs by adolescent male athletes is a significant problem. Participation in sports may encourage use of drugs that enhance athletic performance, especially anabolic steroids (AS). Because, to our knowledge, no other intervention has successfully altered substance abuse by athletes, we developed and assessed the efficacy of a team-centered, sex-specific education program designed to reduce adolescent athletes' intentions to use and use of AS and alcohol and other illicit drugs. METHODS: We studied 31 high school football teams that comprised 3207 athletes in 3 successive annual cohorts (1994-1996). The intervention included interactive classroom and exercise training sessions given by peer educators and facilitated by coaches and strength trainers. Program content included discussion of sports nutrition, exercise alternatives to AS and sport supplements, and the effects of substance abuse in sports, drug refusal role-playing, and the creation of health promotion messages. Questionnaires assessing AS, the use of sport supplements and alcohol and other illicit drugs, and potential risk and protective factors were administered before and after the intervention (before and after the football season) and up to 1 year after the program. RESULTS: At season's end, intentions to use (P<.05) and actual AS use (P<.04) were significantly lower among students who participated in the study. Although AS reduction did not achieve significance at 1 year (P<.08), intentions to use AS remained lower (P = .02). Illicit drug use (marijuana, amphetamines, and narcotics) was reduced at 1 year, whether alcohol was included (P = .04) or excluded (P = .02) from the index. Other long-term effects included fewer students reporting drinking and driving (P = .004), less sport supplement use (P = .009), and improved nutrition behaviors (P<.02). CONCLUSIONS: Use of alcohol and other illicit drugs and associated harmful activities can be prevented with a sex-specific, team-centered education. School athletic teams provide an optimal environment in which to provide drug prevention and health promotion education.     

Ontogeny of Na+/H+ antiporter activity in rat proximal convoluted tubules

Neonates have a lower serum bicarbonate level than adults, which is caused by a lower renal threshold for bicarbonate. Eighty percent of bicarbonate reabsorption occurs in the proximal tubule, in which proton secretion is predominantly mediated by a luminal Na+/H+ antiporter. Previous studies have demonstrated that there is a maturational increase in apical membrane rabbit proximal convoluted tubule Na+/H+ antiporter activity. However, in rat brush border membrane vesicles, Na+/H+ activity was higher in neonates than that in adult rats. To examine the maturation of Na+/H+ antiporter activity in rat proximal convoluted tubules, we perfused rat proximal convoluted tubules in vitro. Na+/H+ antiporter activity was assayed as the proton secretory rate on luminal sodium removal. Na+/H+ antiporter activity was 121.2 +/- 18.4 pmol/mm x min in neonatal and 451.8 +/- 40.6 pmol/mm x min in adult proximal convoluted tubules (p < 0.001). We next examined whether the increase in Na+/H+ antiporter activity was associated with changes in renal cortical NHE3 mRNA and brush border membrane NHE3 protein abundance. Adult renal cortical NHE3 mRNA abundance was 10-fold greater than that in 1-d-old neonates (p < 0.001). There was a comparable developmental increase in renal brush border membrane vesicle NHE3 protein abundance (p < 0.001). In summary, this study demonstrates that there is a maturational increase in rat apical membrane Na+/H+ antiporter activity, renal cortical NHE3 mRNA, and brush border membrane vesicle NHE3 protein abundance.     

Cerebral irradiation causes blunted pubertal growth in girls treated for acute leukemia

The improved treatment of childhood leukemia is a major achievement. The late effects of the treatment need further investigation. Growth inhibition has been demonstrated in earlier studies. Growth and the timing of puberty were studied in 179 girls who had been treated for acute lymphoblastic leukemia (ALL) in Denmark, Finland, Norway, and Sweden. The patients were divided into two groups according to mode of CNS prophylaxis: with or without cerebral irradiation. Longitudinal analysis of 103 patients showed no difference in prepubertal growth in irradiated and nonirradiated girls. Growth during puberty was normal in girls without irradiation and below normal in irradiated girls. There was no difference in growth between girls after 24 Gy or 20 Gy of cerebral irradiation. Irradiated girls had a final height which was one SD less than expected before puberty and menarche occurred one year earlier than in the nonirradiated girls. Prophylactic cerebral irradiation is the most important factor for subnormal growth after treatment for ALL. There is no short-term influence on growth but the effects of irradiation become apparent several years after therapy when girls enter puberty somewhat early and have a subnormal pubertal growth. Growth and growth hormone (GH) levels should be evaluated several years after CNS irradiation, and treatment with GH and/or luteinizing hormone releasing hormone (LHRH) analogues may be considered. © 1994 Wiley-Liss, Inc.     

HYPOPITUITARY DWARFISM The Importance of Early Therapy

Two siblings with hypoglycemia had from early infancy retardation of growth which seemed to be due to isolated deficiency of somatotropin. The father had diabetes mellitus which may be of etiologic significance. They have been followed from birth to the ages of 6 and 7 1/2 years respectively. Experience with long-term therapy with HGH, 2 mg three times weekly, from the age of 3 1/2 and 2 years is reported. A purified HGH preparation which is supposed to contain only the somatotropin proper, seems to be preferable. A reduction of the HGH dosage to 1 mg three times weekly resulted in a marked reduction in height increments, and almost no growth was observed in the short periods without therapy. Total growth during a 4-year-period was 29.5 and 32.5 cm respectively. However, the therapy was probably initiated too late and the height continues to be far below the 2.5 percentile, particularly in the older child. The importance of an adequate therapy from early infancy in the more severe cases of hypopituitary dwarfism is stressed. Attention is drawn to the hematological aspect of hypopituitary dwarfism, and the increased iron requirement during the initial period with catchup growth.     

Percutaneous tracheostomy: a comprehensive evaluation

Percutaneous tracheostomy (PT) is an ancient procedure that has recently attracted increasing interest. While there are numerous publications in the literature, there remains confusion due to the large variety of techniques and instruments with which it has been performed and the wide disparity in clinical outcome. This study evaluates the international literature on over 1,500 cases, classifies the techniques that have been used, analyzes the safety of each method, and reports a prospective outcome and cost analysis of 130 cases undergoing what we determined to be the safest method. We found that PT performed with the correct instruments and technique under bronchoscopic surveillance has a lower incidence of complications than open tracheostomy (OT). Cost estimation demonstrated that PT may be significantly more expensive than bedside OT. While we recommend PT as a relatively safe and expedient method of tracheostomy for selected intubated patients in an intensive care unit, it does not offer an advantage for patients who must be taken to the operating room, and should not deprive house officers of necessary experience in OT in this setting.