Pathogenesis of chronic allograft nephropathy

We found normal individuals whose aspartoacylase gene Y231X mutation site consistently gave no signal in a primer extension assay. We determined the nucleotide sequence of the relevant region of the gene in those individuals, and found a new allele with a thymidine residue at the mutation site instead of a cytidine. Since both TAC and TAT code for tyrosine, this sequence polymorphism has no effect on the amino acid sequence of the ASPA protein. We found the relative frequencies of the 693C and the 693T alleles in the tested population to be 0.75 and 0.25 respectively.     

Approach and avoidance strength during goal attainment: regulatory focus and the "goal looms larger" effect

Three studies tested the hypothesis that regulatory focus, both as a chronic person variable and as a manipulated situational variable, differentially affects the strength of participants' approach and avoidance strategic motivations as they get closer to the goal. In 2 studies, flexion and extension arm pressure were used as on-line measures of approach and avoidance intensity, respectively. As predicted, the approach gradient was steeper for participants with a promotion focus on aspirations and gains than for participants with a prevention focus on responsibilities and nonlosses, whereas the reverse was true for the avoidance gradient. In a third study, the same pattern of results was found on a persistence measure of motivational strength. Participants with a promotion focus worked longer on anagrams closer to the goal when they were approach means for goal attainment than when they were avoidance means, whereas the reverse was true for participants with a prevention focus.     

Epidemiology of work-related aviation fatalities in Alaska, 1990-94

Alaska, with less than one-half of 1% of the United States workforce, accounts for 9% of all occupational aviation fatalities nationally; 30% of all occupational fatalities in Alaska are related to aviation. To understand this high mortality, we investigated occupational aviation crashes to identify risk factors. Occupational aviation fatalities in Alaska during 1990-94 were examined using National Transportation Safety Board reports and merged with records from the Alaska Occupational Injury Surveillance System. There were 876 aircraft crashes; 407 (46%) were work-related. Occupational crashes were 2.2 times (CI: 1.5, 3.2) more likely to result in fatalities than non-occupational crashes. Risk factors identified included poor weather conditions defined as Instrument Meteorological Conditions (IMC). A crash during IMC was 5.3 times (CI: 3.5, 7.9) more likely to result in fatalities than crashes in other conditions. Of aircraft involved in fatal occupational incidents, 33% were not completely destroyed, allowing the potential for survivors. An estimated 30% reduction in fatalities could have occurred if current technology in occupant protection had been used.     

Month of birth and schizophrenia in Taiwan: effect of gender, family history and age at onset

Schizophrenic patients have been shown to have a moderate excess of winter births in the areas where seasonal variations in weather are large. In this report, we examined the seasonality of schizophrenic births in Taiwan, which has a subtropical climate. Using nationwide hospitalization data (2429 male and 1320 female schizophrenic patients), we applied the life table method to compare the risk of schizophrenia among 12 cohorts of month-of-birth for males and females, respectively. Differences among the risks of the 12 cohorts were tested using the logrank test. The samples were further stratified by family history and age at onset. There was a significant association between the risk of being admitted as a schizophrenic and month of birth for both males and females. The cohorts born in November and January had the highest risks. After stratification, the association was significant only for non-familial, male, and early onset schizophrenic patients. The results indicate that seasonally varying factors might increase the risk of schizophrenia, especially in those without a family history of the disease. Men are more vulnerable to such factors than women, and the schizophrenics resulting from such insults tend to be early onset.     

Severing of F-actin by the amino-terminal half of gelsolin suggests internal cooperativity in gelsolin

Gelsolin is a Ca2+-regulated actin-binding protein that can sever, cap, and nucleate growth from the pointed ends of actin filaments. In this study we have measured the binding of the amino-terminal half of gelsolin, G1-3, to pyrene-labeled F-actin as a function of Ca2+ concentration. The rate of binding is shown to be dependent on micromolar concentrations of Ca2+. Independent experiments demonstrate that conformational changes in G1-3 are induced by micromolar concentrations of Ca2+. Titrations of pyrene-F-actin with G1-3 and gelsolin show that the quenching of pyrene fluorescence is identical in extent and stoichiometry for both G1-3 and gelsolin. In contrast, severing of F-actin by G1-3 is found to be much less efficient than is severing by gelsolin. In experiments in which F-actin severing is quantitatively measured, the filament number is found to be proportional to the 1.35 power of the G1-3 concentration. This deviation from linearity may be explained by cooperativity; the binding of two G1-3 molecules in close proximity may lead to cooperative severing of the polymer, thus increasing the severing efficiency. This model is supported by experiments that show that the efficiency of G1-3 severing of F-actin increases with increasing G1-3:F-actin ratios. Extrapolating from these results, we conclude that G4-6, the carboxyl-terminal half of gelsolin, has an active role in the severing of F-actin by intact gelsolin. Whereas F-actin severing by G1-3 is enhanced by cooperative binding of two separate G1-3 molecules, cooperativity is inherent to intact gelsolin because the cooperative partners are covalently linked.     

Clinical presentation of experimentally induced rabies in horses

Twelve naive and nine test-vaccinated horses which developed clinical signs of rabies as a result of the required protocol of a vaccine trial were prospectively observed. Nineteen of the 21 cases were confirmed positive for rabies infection of the brain by fluorescent antibody test. The two horses with negative results had ganglioneuritis of the trigeminal ganglion or lymphocytic perivascular cuffing in the brain stem in addition to clinical signs. Average incubation period was 12.3 days and average morbidity was 5.5 days. Naive animals had significantly shorter incubation and morbidity periods (P < 0.05). Muzzle tremors were the most frequently observed (81%) and most common initial sign. Other common signs were pharyngeal spasm or pharyngeal paresis (71%), ataxia or paresis (71%), lethargy or somnolence (71%). The furious form was manifested in 43% of rabid horses and some of these furious animals initially manifested the dumb form. The paralytic form was not observed. Histopathology was characteristics for rabies. The results of this trial do not reflect on the efficacy of commercially licensed equine rabies vaccines.     

American College of Sports Medicine position stand. Exercise and fluid replacement

It is the position of the American College of Sports Medicine that adequate fluid replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a comprehensive review and interpretation of scientific literature concerning the influence of fluid replacement on exercise performance and the risk of thermal injury associated with dehydration and hyperthermia. Based on available evidence, the American College of Sports Medicine makes the following general recommendations on the amount and composition of fluid that should be ingested in preparation for, during, and after exercise or athletic competition: 1) It is recommended that individuals consume a nutritionally balanced diet and drink adequate fluids during the 24-hr period before an event, especially during the period that includes the meal prior to exercise, to promote proper hydration before exercise or competition. 2) It is recommended that individuals drink about 500 ml (about 17 ounces) of fluid about 2 h before exercise to promote adequate hydration and allow time for excretion of excess ingested water. 3) During exercise, athletes should start drinking early and at regular intervals in an attempt to consume fluids at a rate sufficient to replace all the water lost through sweating (i.e., body weight loss), or consume the maximal amount that can be tolerated. 4) It is recommended that ingested fluids be cooler than ambient temperature [between 15 degrees and 22 degrees C (59 degrees and 72 degrees F])] and flavored to enhance palatability and promote fluid replacement. Fluids should be readily available and served in containers that allow adequate volumes to be ingested with ease and with minimal interruption of exercise. 5) Addition of proper amounts of carbohydrates and/or electrolytes to a fluid replacement solution is recommended for exercise events of duration greater than 1 h since it does not significantly impair water delivery to the body and may enhance performance. During exercise lasting less than 1 h, there is little evidence of physiological or physical performance differences between consuming a carbohydrate-electrolyte drink and plain water. 6) During intense exercise lasting longer than 1 h, it is recommended that carbohydrates be ingested at a rate of 30-60 g.h(-1) to maintain oxidation of carbohydrates and delay fatigue. This rate of carbohydrate intake can be achieved without compromising fluid delivery by drinking 600-1200 ml.h(-1) of solutions containing 4%-8% carbohydrates (g.100 ml(-1)). The carbohydrates can be sugars (glucose or sucrose) or starch (e.g., maltodextrin). 7) Inclusion of sodium (0.5-0.7 g.1(-1) of water) in the rehydration solution ingested during exercise lasting longer than 1 h is recommended since it may be advantageous in enhancing palatability, promoting fluid retention, and possibly preventing hyponatremia in certain individuals who drink excessive quantities of fluid. There is little physiological basis for the presence of sodium in n oral rehydration solution for enhancing intestinal water absorption as long as sodium is sufficiently available from the previous meal.