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Biomedical subjects

V L Larson

Publications and source records attributed to V L Larson.

At least 19 recordsLinked to original sources
PubMed1993

Blood feeding and autogeny in the peridomestic mosquito Aedes bahamensis (Diptera: Culicidae).

Under laboratory conditions, most colony and field-collected Aedes bahamensis Berlin females developed eggs autogenously when they had access to sugar. However, significantly fewer starved females were autogenous, and they produced smaller egg clutches. Autogenous fecundity covaried with wing length, and smaller females generally failed to express autogeny. Mating had no effect on the maturation of the initial egg clutch. Most starved, nulliparous females blood fed from a restrained host. At a south Florida field site, both parous and nulliparous Ae. bahamensis were captured with a power aspirator, but concurrent sampling with dry ice-baited, light traps collected only parous females. Host-seeking females, taken either in chicken-baited traps or as they attempted to blood feed on humans, were also parous, with a single exception. Thus, at this field site, Ae. bahamensis females normally delayed blood feeding until after their first oviposition. Whether or not Ae. bahamensis females in other south Florida populations show a similar gonotrophic pattern probably will depend upon the availability of sugar sources and conditions in the mosquito's aquatic habitat that affect adult size.

Aedes↗
PubMed1991

Measuring mosquito dispersal for control programs.

Simple and economic methods were developed for control programs to demonstrate the movement of mosquitoes from a breeding source to residential areas. Using mark-release-recapture methods and examples, mean, median and maximum distances traveled were estimated or observed and compared for 11 species produced in a wastewater treatment facility near Lakeland, FL. The applicability of these methods and data interpretation for operational mosquito control programs are discussed.

Animals↗
PubMed1990

Parity, fecundity and body size of Mansonia dyari in Florida.

Seasonal trends in reproductive performance and size were examined among female Mansonia dyari. The incidence of parity ranged between 6.9 and 58.1% and averaged 22.5% during an 8-month interval, with 4 peaks in parous rate believed to follow periods of emergence. Parous rates were positively correlated with wing lengths, indicating size-dependent survivorship. Wing lengths were highest in the winter and early spring, decreased to a minimum at the end of summer, and increased in the autumn, showing negative correlations with ambient temperatures recorded prior to adult capture. Female biomasses and fecundities were positively correlated with wing lengths, and their mean values varied significantly among sample dates. Egg development in Ma. dyari was completed by 5.4 days post blood meal at 26 degrees C and 7.6 days at 20 degrees C. No evidence for autogeny was observed.

Animals↗
PubMed1989

Aedes bahamensis: its invasion of south Florida and association with Aedes aegypti.

The exotic mosquito, Aedes bahamensis, is now well-established in south Florida, where it is widely distributed throughout Dade and southern Broward Counties in both urban and rural areas east of the Everglades. When discarded automobile tires were sampled in areas near human habitation, larvae and pupae of Ae. bahamensis were frequently found in association with immature Ae. aegypti. Elsewhere, however, Ae. bahamensis generally occurred in the absence of Ae. aegypti. The persistence of Ae. bahamensis populations at specific sites was documented in egg collections from ovitraps and in larval samples from the water retained in discarded tires.

Aedes↗
PubMed1988

Adrenocorticotropin-containing neoplastic cells in a pars intermedia adenoma in a horse.

Pituitary-dependent hyperadrenocorticism was diagnosed in a 14-year-old Arabian mare with chronic weight loss, hirsutism, polyuria, and polydipsia. The mare had a stress leukogram, glucosuria, and consistent hyperglycemia. Plasma glucose concentrations were resistant to suppression by insulin. Plasma cortisol concentrations were within normal limits, but did not respond to dexamethasone suppression and had an exaggerated response to ACTH stimulation. At necropsy, a chromophobe adenoma of the pars intermedia of the pituitary gland was found. The zona fasciculata of the adrenal cortex and the pancreatic islets of Langerhans were hypertrophied. An immunohistologic staining technique was used to demonstrate ACTH-containing neoplastic cells in the pituitary mass. These cells released ACTH and other peptides that initiated the chain of endocrinologic events leading to clinical disease.

Adenoma↗
PubMed1986

Study on the etiologic role of bovine respiratory syncytial virus in pneumonia of dairy calves.

Bovine respiratory syncytial virus (BRSV) was the viral agent most commonly identified in 14 epizootics of pneumonia in dairy calves. A microtiter serum-virus neutralization test proved to be the best means of identifying involvement of BRSV; seroconversion (fourfold or greater rise in titer) was demonstrated in 10 of the 14 epizootics. Only limited involvement of bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, parainfluenza 3 virus, and bovine adenovirus type 3 was recognized. Pasteurella multocida was isolated in 12 of 14 epizootics, and Pasteurella haemolytica in 4 of 14 epizootics. Mycoplasmal and ureaplasmal agents were isolated in all 14 epizootics.

Animals↗
PubMed1985

Equine tracheobronchial lavage: comparison of lavage cytologic and pulmonary histopathologic findings.

Differential cell counts were done on bronchial lavage specimens from 166 horses. Postmortem gross and histologic examinations were done to determine the pathologic diagnosis of the lungs from these horses. Ninety-two (55%) were normal, 18 (11%) had interstitial pneumonia, 13 (8%) had bronchopneumonia, 13 (8%) had focal eosinophilia, 11 (7%) had diffuse eosinophilia, 11 (7%) had chronic bronchitis, and 8 (5%) had suppurative bronchitis. Little relationship was found between cellular features of the lavage specimens and the pathologic status of the lungs of individual horses.

Animals↗
PubMed1983

Oxytetracycline concentrations in healthy and diseased calves.

Pneumonia was induced in a group of calves that were then treated with oxytetracycline (OTC). When the plasma pharmacokinetics and tissue concentrations of this group were compared with those of healthy controls, obvious differences were observed. The volume of distribution and the half-life of OTC were increased in the group with pneumonia. Tissue concentrations of OTC (1.48 +/- 0.29 microgram/ml) were greater in the lungs of calves with pneumonia than that in the lungs (1.09 +/- 0.09 microgram/ml) of healthy controls. For the dose of OTC used, the correlation between serum concentration and tissue concentrations at 24 hours was poor. Seemingly, current concepts of antibiotic dosages and dosage intervals may be inadequate because they are based on blood and tissue values of healthy animals.

Animals↗
PubMed1981

Plasma and tissue concentrations of oxytetracycline in the horse after intravenous administration.

Oxytetracycline (OTC) was administered IV to 3 clinically normal horses at a dosage of 10 mg of OTC/kg of body weight. Plasma OTC concentrations were determined at 30-minute intervals until postinjection minute (PIM) 240. At PIM 240, the mean OTC concentration in pulmonary tissue was 3.96 microgram/g of tissue (wet weight) and in renal tissue was 25.47 micrograms/g. diluted bronchial fluid had a mean concentration of 0.288 microgram of OTC/ml at PIM 240. The data demonstrated that OTC has adequate tissue distribution in horses.

Animals↗