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Biomedical subjects

N Clark

Publications and source records attributed to N Clark.

At least 19 recordsLinked to original sources
PubMed1992

Feeding the ultraendurance athlete: practical tips and a case study.

With the rising popularity of ultradistance sports events lasting from 6 to 24 hours or multiple days, athletes are consulting registered dietitians for specialized dietary advice. Many dietitians, however, lack experience with these types of events. This article provides basic guidelines ffor fueling the ultradistance athlete. The goals are to maintain normal hydration and blood glucose levels, which can be done by enforcing programmed drinking (approximately 250 to 500 mL/15 minutes, depending on the athlete's sweat rate and environmental temperature) and programmed eating (1 to 1.5 + g of carbohydrate per kilogram of body weight per hour, depending on the athlete's acceptance of and tolerance to solid and/or liquid foods during exercise). Athletes who compete longer than 6 to 8 hours should consume adequate electrolytes, particularly sodium (approximately 1 g/hour) through either sports drinks or foods. These guidelines are applied to a case study of the 1991 women's winner of the Race Across America, a 2,930-mile biking event.

Bicycling↗
PubMed1991

Efficacy and safety field trials of a recombinant DNA vaccine against feline leukemia virus infection.

A new recombinant gp70 vaccine was found to be safe and effective for prevention of infection by FeLV. The vaccine incorporates a unique purified saponin adjuvant with the recombinant antigen. Serious systemic reactions were not observed during the efficacy trial. Local reactions were transient and mild. More than 2,000 doses were administered to a cross section of household cats in a field safety trial. Only 1 cat had hypersensitivity reaction, which resolved. Among veterinarians who used the vaccine and the cat owners, the vaccine was judged satisfactory and safe. After rigorous intraperitoneal challenge exposure without use of immunosuppressants, 100% of the controls in the efficacy trial became infected, 70% of which remained persistently infected with FeLV. Among vaccinates, 45% were never viremic and 40% cleared transient infection within 12 weeks after challenge exposure. Of the 20 vaccinated cats, 3 were persistently infected. Overall, 85% of cats vaccinated with this recombinant DNA FeLV vaccine resisted persistent FeLV infection after stringent challenge exposure, which translates to preventable fraction of 78.6%.

Adjuvants, Immunologic↗
PubMed1991

Nutritional concerns of female athletes: a case study.

Some of the nutritional concerns of female athletes are highlighted in this case study of a 20-year-old woman who wants to lose 16% of her body weight to qualify for the position of coxswain on a national crew team. These concerns include adequacy of vitamin, mineral, protein, and carbohydrate intake as well as amenorrhea and pathogenic eating behaviors.

Adult↗
PubMed1990

Patterns and mechanisms of beta-lactam resistance among isolates of Escherichia coli from hospitals in the United States.

To study the national distribution of beta-lactam resistance patterns and mechanisms among Escherichia coli organisms isolated in U.S. hospitals, 652 ampicillin-resistant (Am(r)) or ampicillin-intermediate (Ami) isolates were submitted to the Centers for Disease Control from March 1983 through July 1984 by nine hospitals participating in the National Nosocomial Infections Study. Among the isolates (most of which caused urinary tract infections), 78% were Am(r) and 22% were Ami by the interpretative criteria established by the National Committee for Clinical Laboratory Standards. Resistance to carboxypenicillins ranged from 73 to 74%, and that to acylureidopenicillins ranged from 43 to 66%. A total of 26% of the isolates were resistant to cephalothin, and 4% were resistant to cefazolin. Resistance to cefoxitin was 1%, while resistances to cefuroxime and cefamandole were 2 and 7%, respectively. With the exception of cefsulodin (98% resistant) and cefoperazone (1% resistant), there was no resistance to newer cephalosporins or aztreonam. In general, only minor differences in the incidence of resistance to beta-lactam antibiotics were noted in hospital-acquired versus non-hospital-acquired isolates as well as among isolates from various regions of the United States. TEM beta-lactamases were produced by 87% of the 237 Am(r) isolates examined. By our methods, OXA and chromosomal (type I) beta-lactamases were detected in 2 and 28 isolates, respectively, and plasmid-mediated extended-spectrum cephalosporinases were detected in none of the isolates. Disk substrate and clavulanic acid inhibition assays revealed that TEM beta-lactamase conferred Am(r) and resistance to carboxypenicillins, acylureidopenicillins, cephalothin, cefamandole, cefsulodin, and cefoperazone. A total of 391 isolates were screened for plasmids, and 259 isolates were examined by DNA hybridization with a TEM probe. Among 462 plasmids probed, 129 plasmids, ranging from 4 to 140 megadaltons, harbored TEM sequences. Although beta-lactam resistance in clinical isolates of E. coli is predominantly mediated by TEM beta-lactamase, the diverse spectrum of resistance appears to be related to additional strain=dependent factors.

Ampicillin↗
PubMed1989

The effects of a topical PGE2 analogue on global flap ischemia in rats.

The present study evaluated the ability of DHV-PGE2ME, a topically effective 16-vinyl prostaglandin E2 analogue, to improve the tolerance of skin flaps to a period of ischemia. DHV-PGE2ME and placebo were applied to bilateral island flaps on 70 anesthetized rats; then the vascular pedicle of each flap was clamped for 10 hours. Treated flaps evidenced significantly better reperfusion, as documented by quantification of fluorescein dye delivery at 90 minutes after clamp release, and they had significantly greater ultimate viability (p less than 0.05, by ANOVA). While less than 3 percent of untreated flaps survived, those treated with 1.75 and 17.5 microgram/cm2 of drug evidenced 76 and 86 percent survival, respectively. Treatment of a given flap did not affect its contralateral mate, since there was no evidence of a systemic effect. Especially since its effect can be limited to the site of application, DHV-PGE2ME should be valuable for the treatment of compromised perfusion in a variety of settings.

Administration, Topical↗
PubMed1989

Epidemic of Serratia marcescens bacteremia in a cardiac intensive care unit.

From 16 July through 27 September 1988, seven cases of nosocomial Serratia marcescens bacteremia occurred in a cardiac care unit. In all seven case patients, S. marcescens was isolated from blood cultures. Two of the seven had other microorganisms identified in the blood culture in which S. marcescens was recovered; one had Enterobacter cloacae, and one had Klebsiella pneumoniae. A case-control study was conducted to identify risk factors for bloodstream infection. Case patients were more likely than controls to have been exposed to an intra-aortic balloon pump pressure transducer (7 of 7 versus 6 of 21; P = 0.001) and to a pulmonary arterial pressure transducer (7 of 7 versus 8 of 21; P = 0.005). Cultures of in-use and in-storage transducers revealed bacterial contamination of the pressure-sensitive membranes of the transducers. S. marcescens blood culture isolates obtained from five of the seven case patients, as well as six S. marcescens isolates from cultured transducers, belonged to serotypes Oundetermined:H1 and Oundetermined:H18. E. cloacae isolates from one case patient and from two stored and two in-use transducers had identical antimicrobial suceptibility patterns. Review of cardiac care unit disinfection practices revealed that the transducers were not processed with high-level disinfection or sterilization between patient uses. We concluded that the transducers had served as reservoirs for this outbreak of bloodstream infection. Because intra-aortic balloon pumps with pressure transducers are being used more frequently in the management of critically ill cardiac patients, their role as infectious reservoirs should be considered in the investigation of nosocomial bacteremia.

Cross Infection↗
PubMed1988

The effect of paternal social support on maternal disruption caused by childhood asthma.

Baseline data obtained from a study of 228 low-income Black and Hispanic mothers of children with asthma were analyzed to test the hypothesis that the presence of adults in the household, and paternal involvement in asthma care would be associated with less disruption of mothers' daily activities due to the child's asthma. The data were analyzed using multiple regression techniques. We controlled for other variables that might affect the amount of disruption that mothers reported, including the child's age and severity of asthma. The mere presence of other adults in the household, including the father, was not significantly associated with disruption. The frequency of the father's involvement in the care of the child's asthma was inversely associated with disruption regardless of his presence in the household. Hispanic ethnicity and severity of the child's asthma were directly associated with disruption while the age of the child was inversely associated with disruption. We conclude that it is a specific type of assistance (sharing asthma tasks) rendered by fathers living within or outside of the household that reduces disruption reported by mothers. The study suggests that health care providers can improve education and counseling for families who have a child with asthma by emphasizing to fathers their importance in the care of asthma, and by helping them identify specific actions they can take to manage the child's disease.

Adult↗
PubMed1987

The effect of burn wound size on resting energy expenditure.

Numerous formulas have been used to estimate the calorie requirements of hypermetabolic burned patients. With the recent development of instrumentation for indirect calorimetric measurements, questions have been raised concerning the validity and accuracy of the early equations. Because metabolic rate decreases during the course of wound healing, we attempted to determine the magnitude of hypermetabolism and the accuracy of the Curreri formula in patients with various wound sizes. Twenty-eight patients with a mean initial burn size of 29% body surface area (BSA) had measurements of resting energy expenditure (REE) at regular intervals during their postburn course. Concomitantly, basal energy expenditure (BEE) was calculated from the Harris-Benedict equation; and the predicted energy needs were calculated using the Curreri formula adjusted for current wound size (ACEE). Three significantly different burn size (%BSA) groups were identified: Group 1, 1-10%; Group 2, 11-30%; and Group 3, 31-60% BSA. The measured REE was 27, 35, and 50% greater than the BEE in Groups 1, 2, and 3, respectively (p less than 0.001). The ACEE underestimated REE by 7% in Group 1, and overestimated REE by 13 and 35% in Groups 2 and 3, respectively (p less than 0.001). Resting energy expenditure should be measured at regular intervals in individuals with open burn wounds greater than 10% BSA in order to adjust nutritional support appropriately.

Adult↗
PubMed1987

Plasmids of Ewingella americana: supplementary epidemiologic markers in an outbreak of pseudobacteremia.

During an outbreak of pseudobacteremia in a children's hospital, Ewingella americana was found in blood cultures from 20 patients. E. americana was inoculated into blood culture bottles at the time of specimen collection due to cross contamination from nonsterile, citrated blood collection tubes used for coagulation studies. Antimicrobial susceptibility testing and plasmid profiling were used to assess the association between patient isolates and isolates from unused blood collection tubes. All E. americana isolates had similar antibiograms (i.e., resistance only to cephalothin) when tested at 37 degrees C. However, when the same isolates were tested for antimicrobial susceptibility at 25 degrees C, a different antibiogram (i.e., resistance to chloramphenicol, ampicillin, and cephalothin) was found. The majority of these isolates also demonstrated a unique four-plasmid profile (130, 56, 4.6, and 3.1 megadaltons), and two of these plasmids (130 and 56 megadaltons) were characterized as temperature-sensitive plasmids. An epidemiologic link between outbreak-associated isolates obtained from different time periods in the outbreak was supported by evidence of a significant trend in the ability of the outbreak-associated isolates to reduce nitrate, together with the presence of the resistance antibiogram at 25 degrees C and the demonstration of the unique four-plasmid profile.

Adolescent↗
PubMed1979

Fiber dimensions and aspect ratio of crocidolite, chrysotile and amosite particles detected in lung tissue specimens.

Chrysotile, amosite and crocidolite fibers detected in autopsy tissue specimens from cases of mesothelioma and controls have been characterized by particle length, diameter and aspect ratio using a transmission electron microscope. The pooled information from such specimens reveals that the fibers of each mineral type detected in biological material have very different physical characteristics although in all samples fibers less than 5 microns in length are predominant by number while fibers over 25 microns in length are found very infrequently. Chrysotile fibers on average appear as the shortest fibers with the most fine diameter distribution, amosite fibers are on average the longest with the most coarse diameter distribution, crocidolite fibers on average have dimensions which are intermediate between both chrysotile and amosite. The percentage number of fibers of chrysotile, amosite and crocidolite detected with an aspect ratio less than or equal to 10 were 31.7%, 24.2% and 18.5% respectively.

Asbestos↗