Comparison of sweat loss estimates for women during prolonged high-intensity running

PURPOSE: This study evaluated the error produced by four commonly used field estimates and two prediction equations of total body sweat loss. METHODS: Eight women distance runners were studied during a 30-km treadmill run (approximately 70% .VO(2max)) in a warm (30 degrees C T(db)) and a cool (14 degrees C T(db)) environment. Total sweat loss (TSL) was determined from changes in body mass corrected for fluid intake (FI), urine losses (UL), clothing (trapped sweat, TS), CO(2)-O(2) exchange (metabolic mass loss, MML), and respiratory water loss (RWL). TSL was compared with four estimates of sweat losses (often employed in the field) from body mass changes corrected for: a) FI only (F-1); b) FI and TS (F-2); c) FI and UL (F-3); or d) FI, TS, and UL (F-4). Two prediction equations were used also for comparison to TSL values. RESULTS: In the warm environment, F-1, F-3, and F-4 accurately estimated (0.2-6.9%; P > 0.05) TSL, whereas F-2 produced a large error (15.3%; P < 0.05). In the cool environment, all four estimates produced large errors (14-41%; P < 0.05). Both prediction equations markedly underestimated (20-22%) TSL in the warm environment and underestimated (41%) or overestimated (20%) TSL in the cool environment. CONCLUSION: TSL can be accurately estimated from changes in body mass using F-1, F-3, or F-4 methods in hot environments; however, none of the methods accurately estimated actual TSL values in a cool environment. Neither prediction equation provided accurate estimates of TSL in warm or cool conditions for women runners. These results illustrate the difficulty of accurately estimating and predicting sweat losses in the field.     

Prevalence and impact of chronic childhood conditions in Auckland, New Zealand

Objective : To establish the prevalence of specific chronic conditions of childhood in the Auckland area and to quantify resource use by these children.
Methodology : Estimates were made from available registry data and published data sources of the population of children with selected chronic conditions resident in the Auckland Area Health Board area. Resource use data were extracted for admissions to Auckland public hospitals and from providers of community based technology services.
Results : The largest community prevalence groups are those with asthma, intellectual handicap, congenital heart disease and epilepsy. Children aged 0-14 with chronic conditions accounted for at least 14340 hospital days stay in Auckland in 1992 at an estimated minimum cost of $7.9 million. Over 200 children are dependent on technological aids at home.
Conclusions : There are sparse data on the numbers and needs of children with chronic conditions in the population. A non-categorical approach which crosses disease entities may be the best method of meeting common needs.     

Chemoprevention of spontaneous tumorigenesis in nullizygous p53- deficient mice by dehydroepiandrosterone and its analog 16alpha-fluoro- 5-androsten-17-one

Transgenic mice with both alleles of the p53 tumor suppressor gene product 'knocked out' by gene targeting are susceptible to early development of tumors, chiefly lymphomas and sarcomas. Compared with the control group, administration of dehydroepiandrosterone (DHEA) at 0.3% of the diet to male p53-deficient mice extended their lifespan by delaying death due to neoplasms (from 105 to 166 days on study, P = 0.002), primarily by suppressing lymphoblastic lymphoma (from 45 to 6% of neoplastic deaths, P = 0.010). Treatment with a synthetic DHEA analog, 16alpha-fluoro-5-androsten-17-one (compound 8354), at 0.15% of the diet also increased lifespan, to 140 days for mice that developed tumors (P = 0.037). The effects of these steroids on lifespan and tumor development did not appear to be strongly related to inhibition of food consumption and weight gain, in that a group pair-fed with control diet to the reduced food consumption of the DHEA-treated group developed and died of the same types of neoplasms at the same rate as the controls fed ad libitum. The chemopreventive effect of these steroids has been proposed to be due to suppression of DNA synthesis by inhibition of glucose 6-phosphate dehydrogenase, the rate-limiting enzyme of the pentose phosphate pathway. Although DHEA and its analog are strong non- competitive inhibitors of this enzyme in vitro, treatment with DHEA did not deplete cellular nucleotide pools in the liver, as would have been predicted. The chemopreventive effect of DHEA in this model may be due to steroid-induced thymic atrophy and suppression of T cell lymphoma, permitting these mice to survive long enough to develop tumors with longer latency.      

Fatal meningoencephalitis due to Bacillus anthracis

Abstract: We report the first case of fatal anthrax meningoencephalitis in Hong Kong over the past 60 years. A 13 year-old boy presented with right lower quadrant pain, diarrhoea and progressive headache. Lumbar puncture yielded gram positive bacilli initially thought to be Bacillus cereus, a contaminant. He was treated with ampicillin and cefotaxime, but died 3 days after hospitalization. The organism isolated from blood and cerebrospinal fluid was later identified as Bacillus anthracis.     

Daily body mass variability and stability in active men undergoing exercise-heat stress

The purpose of this study was to quantify the variability and stability of 1st morning body mass (BM) fluctuations during daily exercise in the heat while following traditional fluid intake guidance. Data from 65 men were examined retrospectively. BM fluctuations were monitored over 4 to 15 consecutive days. Group daily variation in BM was 0.51+/-0.20 kg. Group coefficient of variation was 0.66+/-0.24%, normally distributed, and not related to either absolute BM (r = 0.04) or number of measurements (r = 0.34). Three days resulted in a similar variability estimate compared to 6 or 9 d, although precision was improved with 9 d. In conclusion, 3 consecutive BM measurements provide an accurate assessment of daily BM variability, which is less than 1% for active men when replacing 100% of sweat losses during exercise. The data also suggest that daily BM is a sufficiently stable physiological parameter for potential daily fluid balance monitoring.     

Going Against the Grain: Flaws in the Zone Diet

The Zone Diet is an eating plan claiming to maintain an “ideal” hormone balance and improve health through the manipulation of dietary carbohydrate and protein. Although popular, the diet’s health claims are based on dubious information and misinterpreted scientific facts, and it ultimately remains unsubstantiated.     

A RANDOMISED,DOUBLE-BLIND,PARALLEL-GROUP COMPARISON OF VENLAFAXINE AND DOTHIEPIN IN GERIATRIC PATIENTS WITH MAJOR DEPRESSION

This randomised, double-blind study conducted at nine sites in the UK and the Netherlands compared the safety and antidepressant efficacy of venlafaxine and dothiepin. Ninety-two geriatric patients (aged 64-87 years) with major depression were randomly assigned to receive either venlafaxine or dothiepin for up to 43 days. The dose of venlafaxine or dothiepin was titrated up to a maximum of 150 mg per day for the first 15 days, and thereafter could range from 50 to 150 mg per day. Adjusted mean scores on the MADRS and the HAM-D decreased significantly (p 0.05) from baseline to the end of the study in both groups. A response to therapy was observed in 60% of patients in the venlafaxine group and 53% of patients in the dothiepin group on the MADRS, and in 60% of patients in both groups on the HAM-D. Suicidal ideation scores on the MADRS were significantly (p=0.042) lower in the venlafaxine group at week 6. Treatment-emergent study events were the primary reason for withdrawal in only 7% of venlafaxine-treated patients and 8% of dothiepin-treated patients. The results confirm the efficacy and tolerability of venlafaxine for treating major depression in the elderly.