Sex differences in circulatory oxygen transport parameters of sockeye salmon (Oncorhynchus nerka) on the spawning ground.

Upon reaching sexual maturity, several species of male salmonids possess a relative ventricular mass (rM(V)) that may be up to 90% larger than females. This can increase maximum cardiac stroke volume and power output, which may be beneficial to increasing the oxygen transport capacity of male salmonids during the spawning period. It may be further hypothesized, therefore, that other variables within the circulatory oxygen transport cascade, such as blood oxygen-carrying capacity and heart rate, are similarly enhanced in reproductively mature male salmonids. To test this idea, the present study measured a range of circulatory oxygen transport variables in wild male and female sockeye salmon (Oncorhynchus nerka) during their spawning period, following a 150 km migration from the ocean. The rM(V) of male fish was 13% greater than females. Conversely, the haemoglobin concentration ([Hb]) of female fish was 19% higher than males, indicative of a greater blood oxygen-carrying capacity (138 vs. 116 ml O2 l(-1), respectively). Surgically implanted physiological data loggers revealed a similar range in heart rate for both sexes on the spawning ground (20-80 beats min(-1) at 10 degrees C), with a tendency for male fish to spend a greater percentage of time (64%) than females (49%) at heart rates above 50 beats min(-1). Male fish on average consumed significantly more oxygen than females during a 13-h respirometry period. However, routine oxygen consumption rates (.)MO2 ranged between 1.5 and 8.5 mg min(-1) kg(-1) for both sexes, which implies that males did not inherently possess markedly higher routine aerobic energy demands, and suggests that the higher [Hb] of female fish may compensate for the smaller rM(V). These findings reject the hypothesis that all aspects of the circulatory oxygen transport cascade are inherently superior in male sockeye salmon. Instead, it is suggested that any differences in (.)MO2 between sexually mature male and female sockeye salmon can likely be attributed to activity levels.

Moving with the beat: heart rate and visceral temperature of free-swimming and feeding bluefin tuna.

Owing to the inherent difficulties of studying bluefin tuna, nothing is known of the cardiovascular function of free-swimming fish. Here, we surgically implanted newly designed data loggers into the visceral cavity of juvenile southern bluefin tuna (Thunnus maccoyii) to measure changes in the heart rate (fH) and visceral temperature (TV) during a two-week feeding regime in sea pens at Port Lincoln, Australia. Fish ranged in body mass from 10 to 21 kg, and water temperature remained at 18-19 degrees C. Pre-feeding fH typically ranged from 20 to 50 beats min(-1). Each feeding bout (meal sizes 2-7% of tuna body mass) was characterized by increased levels of activity and fH (up to 130 beats min(-1)), and a decrease in TV from approximately 20 to 18 degrees C as cold sardines were consumed. The feeding bout was promptly followed by a rapid increase in TV, which signified the beginning of the heat increment of feeding (HIF). The time interval between meal consumption and the completion of HIF ranged from 10 to 24 hours and was strongly correlated with ration size. Although fH generally decreased after its peak during the feeding bout, it remained elevated during the digestive period and returned to routine levels on a similar, but slightly earlier, temporal scale to TV. These data imply a large contribution of fH to the increase in circulatory oxygen transport that is required for digestion. Furthermore, these data oppose the contention that maximum fH is exceptional in bluefin tuna compared with other fishes, and so it is likely that enhanced cardiac stroke volume and blood oxygen carrying capacity are the principal factors allowing superior rates of circulatory oxygen transport in tuna.

The effects of driving cessation on the elderly with dementia and their caregivers.

This research explores how the loss of driving privileges by impaired drivers affects households. The particular focus is on the travel behavior and preceptions of people living in households where an elderly driver has had his or her license revoked due to Alzheimer's disease or a related dementia. The data for this analysis were drawn from a 1996 survey of households in California which queried the caregivers of people with dementia on how the former drivers access necessary destinations once they can no longer drive, and on the difficulties faced by other household members in seeking alternative means of transportation. After losing their license, the vast majority of people surveyed depended on informal support systems for transportation, such as rides from family and friends. Although such arrangements were not reported to be a problem for the majority of households, certain groups of non-drivers reported difficulty accessing services, particularly social and recreational destinations. The most commonly reported problem was a lack of available licensed drivers to chauffeur non-drivers. Importantly, no increase was observed in the number of people walking, using public transit, taxis, or van services following license revocation. People who did not live with at least one licensed driver and those who were younger and healthier reported the greatest mismatch between their need and desire to travel and the availability of transportation. In addition, some caregivers reported that they frequently missed work or stopped working entirely in order to care for and chauffeur people in the former drivers' household. Overall, these findings reinforce the importance of both developing transportation policies to support the functioning of informal transportation structures and in improving the range of alternative transportation options for those individuals with particular disabilities--like dementia--who are not well served by either informal arrangements or by formal transportation services for the disabled.

Factors related to noncompliance with screening mammogram appointments among low-income African-American women.

Despite current mammography recommendations, screening rates among African-American women are suboptimal. The purpose of this case-control study was to identify the psychological, demographic, and health care system barriers to screening mammography use among low-income African-American women. A total of 574 women with screening mammogram appointments at an urban hospital were interviewed to determine the predictors of mammogram appointment noncompliance. Predictor variables included: demographics; breast cancer knowledge, attitudes, beliefs, and screening practices; and type of health care provider making the referral. Age was inversely related to mammogram appointment noncompliance. Relative to women 40 to 49 years old, women 70 years of age and older were the least likely to miss their appointments (odds ratio [OR], 0.3; 95% confidence interval [CI], 0.2, 0.5). Women referred for mammography by a physician's assistant or nurse practitioner were less likely to miss their appointments than women referred by a physician (OR, 0.3; 95% CI, 0.1, 0.8). Embarrassment, lack of breast symptoms, and forgetfulness also contributed to noncompliance. Key demographic, attitudinal, and health care system factors hinder low-income African-American women from obtaining screening mammograms. These findings have significant health education and policy implications for health care delivery to women in this population.

Bronchoalveolar lavage for diagnosis of fungal disease. Five years' experience in a southern United States rural area with many blastomycosis cases.

OBJECTIVE: To determine the relative frequency of Blastomyces dermatitidis among other microorganisms in bronchoalveolar lavage (BAL) specimens. STUDY DESIGN: The study group consisted of 208 BAL specimens received from 192 patients from March 1988 to August 1993. RESULTS: Forty-seven specimens from 42 patients were positive for pathogenic microorganisms, and 2 other specimens were diagnostic of malignancy. Pneumocystis carinii (23 specimens) was the most common microorganism found in the specimens. Candida spp (10 specimens) was the second most common microorganism, and B dermatitidis (5 specimens) was the third. Cryptococcus neoformans (3 patients), Histoplasma capsulatum (2 patients) and Conidiobolus coronatus (1 patient) were the other fungi detected in BAL. Acid-fast bacilli, cytomegalovirus and herpes simplex virus were also found (1 patient each). Several patients had more than one organism. CONCLUSION: B dermatitidis was the third most common microorganism found in BAL specimens at our hospital.

Maternal factors, birthweight, and racial differences in infant mortality: a Georgia population-based study.

Black infant mortality rates (IMRs) are approximately twice those of whites in Georgia and nationwide. This study evaluates maternal factors, particularly marital status, that influence racial differences in infant mortality. Population-based data on 565,730 live births and 7269 infant deaths in Georgia from 1980 to 1985 were examined. The IMR ratio for unmarried compared to married mothers was calculated and adjusted singly for maternal education, age and race, and infant birthweight. In addition, racial differences in IMR were estimated using stratified analysis on the basis of four factors: infant birthweight, maternal age, marital status, and education. When only normal birthweight infants were considered, the IMR, adjusted for maternal education level, was highest for infants born to unmarried black teens (9.5/1000 live births), followed by that for infants born to married black teens (9.1), unmarried black adults (7.5), married black adults (4.8), married white teens (4.4), married white adults (3.4), unmarried white adults (2.4), and unmarried white teens (1.3). When only low birthweight infants were considered, the highest IMR per 1000 was found in infants born to married black adults (119), followed by unmarried black adults (103), married black teens (99.9), unmarried black teens (92.5), married white adults (92.1), married white teens (79.0), unmarried white adults (38.0), and unmarried white teens (26.3). These differences led to a black-to-white IMR risk ratio from 1.3 for low birthweight infants born to unmarried teen or adult mothers to 3.7 for normal birthweight infants born to unmarried teen mothers.(ABSTRACT TRUNCATED AT 250 WORDS)

Thoracoabdominal aortic aneurysm repair in a 15-month-old child.

This case report describes a young child with a thoracoabdominal aortic aneurysm, a very rare condition in pediatrics. The anesthetic management for resection of the aneurysm and repair of the aorta are presented, and special considerations for pediatric patients are discussed.

Through the art of children: perceptions of alcohol use and abuse.

Through analysis of children's art, submitted as alcohol education posters, insight was gained as to what children believe to be the effects of alcohol use. More than 5,000 posters were submitted by children in grades one-13 in two poster contests sponsored by the Addiction Research Foundation of Ontario in 1982 and 1984. Most posters were submitted by students in grades four-eight. The most common messages were "Don't Drink" and slogans about drinking and driving. Other messages included use within the family, use with friends, use and sports, use leading to death, physical effects, and solutions to drinking. The message never to drink was prominent, but few posters advocated drinking in moderation.

Pharmacokinetics and pharmacodynamics of cimetidine and metabolites in critically ill children.

Cimetidine and antacids are the mainstays of therapy for the prophylaxis of stress-induced ulceration in critically ill children. Previous cimetidine dosing recommendations have been empiric because of a lack of knowledge about cimetidine disposition kinetics in children. Thirty children, mean age 9 +/- 3.2 years, were admitted to the study with the following primary diagnoses: closed head injury (23 patients), sepsis (four), gunshot wound (two), and bleeding gastric ulceration (one). The mean dose of cimetidine was 26 mg/kg/day, administered intravenously over 15 minutes in four divided doses. Cimetidine disposition was best described by a biphasic elimination curve with t1/2 values for cimetidine, cimetidine sulfoxide, and hydroxymethyl cimetidine of 1.39, 2.6, and 4.7 hours, respectively. Cimetidine plasma concentrations were maintained at greater than or equal to 0.5 microgram/ml for a significantly longer time in patients who received greater than or equal to 20 mg/kg/day. Most patients had a plasma cimetidine concentration below 0.5 to 1.0 microgram/ml 4 hours after infusion. The mean apparent volume of distribution and total body clearance for cimetidine were 1.23 L/kg and 10.4 ml/min/kg, respectively. A significant correlation was found between age and either apparent volume of distribution (r = 0.76, P less than 0.001) or total body clearance (r = 0.75, P less than 0.001). No significant correlation between cimetidine concentrations in either plasma or gastric juice and gastric pH could be determined. However, seven of nine patients who received only cimetidine had a gastric pH of greater than or equal to 4 at 2 hours after infusion when the plasma cimetidine concentration was greater than or equal to 1.0 or the gastric juice concentration was greater than or equal to 2.0 microgram/ml. The mean gastric pH was 2.2 at 6 hours, when plasma and gastric juice concentrations of cimetidine were greater than or equal to 1.0 microgram/ml. On the basis of our data, a cimetidine dosage of 20 to 30 mg/kg/day administered in six divided doses should provide for average steady-state plasma cimetidine concentrations of 1.3 to 2.0 micrograms/ml.

The pharmacokinetics of cimetidine and metabolites in a neonate.

Limited pharmacokinetic data have been reported concerning the use of cimetidine in the neonate for the management of gastrointestinal hemorrhage. After receiving cimetidine at a dose of 10 mg/kg/d in a full-term infant, the steady-state peak and four-hour concentrations were 3.5 and 1.8 micrograms/ml, respectively. A mean half-life of 3.6 h for cimetidine and 2.2 h for cimetidine sulfoxide were determined. The cimetidine half-life was prolonged, and the total body clearance decreased as compared with values reported in critically ill children and adults.