Search PubMed⌕ Search

Biomedical subjects

D W Watson

Publications and source records attributed to D W Watson.

At least 19 recordsLinked to original sources
PubMed2002

Managing the horn fly (Diptera: Muscidae) using an electric walk-through fly trap.

An electric walk-through fly trap was evaluated for the management of the horn fly, Hematobia irritans (L.), on dairy cattle in North Carolina over 2 yr. The trap relies on black lights and electrocution grids to attract and kill flies that are brushed from the cattle passing through. During the first season, horn fly densities were reduced from >1,400 to <200 flies per animal. Horn fly density averaged 269.2 +/- 25.8 on cattle using the walk-through fly trap twice daily, and 400.2 +/- 43.5 on the control group during the first year. The second year, seasonal mean horn fly density was 177.3 +/- 10.8 on cattle using the walk-through fly trap compared with 321.1 +/- 15.8 on the control group. No insecticides were used to control horn flies during this 2-yr study.

Animals↗
PubMed2001

Vector competence of Musca domestica (Diptera: Muscidae) for Yersinia pseudotuberculosis.

The vectoR potential of adult house flies. Musca domestica L., for Yersinia pseudotuberculosis (Pfeiffer), a pathogen of domestic animals and humans, was investigated. Adult flies were allowed to feed on trypticase soy broth (TSB) containing Y. pseudotuberculosis for 6 h and then transferred to sterile containers with sterile TSB as a source of water and nutrients. At 6-h intervals, all flies were transferred to sterile containers with sterile TSB and 10 randomly selected flies were examined for the pathogen. Yersinia pseudotuberculosis did not establish a permanent population in the house fly colony; however, viable cells were detected from the digestive tract of flies for up to 36 h after the initial exposure, and flies contaminated their environment (sterile TSB) for up to 30 h after the exposure. These results demonstrated that house flies can carry Y. psedotuberculosis for a considerable period and therefore must be considered as a potential mechanical vector of pseudotuberculosis infection.

Animals↗
PubMed2000

Limited transmission of turkey coronavirus in young turkeys by adult Alphitobius diaperinus (Coleoptera: Tenebrionidae).

We examined the role of lesser mealworm, Alphitobius diaperinus (Panzer), in the transmission of an enteric disease of turkeys caused by a coronavirus. Turkey coronavirus (TCV) from two sources was studied, one isolate (NC95) was embryo propagated, the second was TCV infected material from turkeys diagnosed with poult enteritis mortality syndrome (PEMS). Beetles were fed virus-infected feces mixed with chicken feed. Transmission of virus was effectively halted by surface sterilization of the beetles. Turkey poults administered beetle homogenates infected with TCV+ PEMS that had not been surface sterilized had reduced weight gains and 50% mortality. Mortality and weight gains were not effected in the NC95 group. Virus isolation procedures were performed to determine NC95 viability at varying time intervals. Beetles were dissected and the guts removed 1, 12, and 24 h after the initial viral feeding. Whole beetles were also examined for comparison. Whole beetles and beetle guts were homogenized and injected into turkey eggs for embryo propagation. Direct immunofluorescence was used to determine the presence of TCV. A. diaperinus were capable of mechanical transmission of TCV. However, only turkey embryos receiving whole beetle and beetle gut homogenates within 1 h of feeding on the virus were positive for TCV. Laboratory studies demonstrating PEMS transmission by A. diaperinus are continuing.

Animals↗
PubMed2000

Diversity and contribution of the intestinal bacterial community to the development of Musca domestica (Diptera: Muscidae) larvae.

The bacterial diversity in the intestinal tract of Musca domestica L. was examined in larvae collected from turkey bedding and corn silage. Aerobic culturing yielded 25 bacterial species, including 11 from larvae collected from turkey bedding and 14 from larvae collected from corn silage. Providencia rettgeri (Hadley, Elkins & Caldwell) was the only species common to both environments. Two mammalian pathogens, Yersinia pseudotuberculosis (Pfeiffer) and Ochrobactrum anthropi (Holmes), were isolated from the larval intestinal tracts. The majority of isolates represented facultatively anaerobic heterotrophs capable of fermentation. The significance of these bacteria for development of house fly larvae was evaluated by bioassays on trypticase soy egg yolk agar. Pure cultures of individual bacterial species isolated from the intestinal tract of larvae from turkey bedding supported development of flies to a much greater extent than those isolated from larvae from corn silage. House fly development was best supported by a Streptococcus sanguis (White) isolate. The significance of bacteria for development of house flies is discussed.

Agar↗
PubMed1999

Fungal mastoiditis in immunocompromised children.

The immunocompromised host is subject to a variety of opportunistic infections. Mycotic infections, including invasive fungal sinusitis, are a dreaded complication in immune deficient children. Fungal mastoiditis has rarely been described in this population. Our experience with 2 cases of fungal mastoiditis in immunocompromised children is reviewed. Case histories describing aggressive medical management with and without surgical intervention and a review of the literature are presented.

Adolescent↗
PubMed1998

Attachment-site patterns of adult blacklegged ticks (Acari: Ixodidae) on white-tailed deer and horses.

The attachment site pattern of adult Ixodes scapularis Say on white-tailed deer and horses in Maryland was determined by whole-body examinations during fall and spring periods of tick host-seeking activity. On deer in the fall, both female and male I. scapularis attached largely to anterior dorsal body regions, with attachment to the ears (outside), head, neck, and brisket accounting for 87.9% of females and 86.6% of males. The attachment pattern of females differed between bucks and does during fall, but not in spring, and both females and males were more abundant on bucks than does during fall, but not in spring. Neither female nor male attachment patterns on deer differed between fall and spring seasons. In contrast to deer, the ears and neck of horses were largely devoid of blacklegged ticks, and 84% of the females were attached either on the chest, in the axillae of the fore and rear legs, or under the jawbone. The restricted attachment of female blacklegged ticks to ventral body regions of horses may reflect avoidance of light. An understanding of the attachment patterns of adult I. scapularis, an increasingly abundant and economically important species, enhances sampling of feeding ticks, deticking to limit host irritation or exposure to tick-borne pathogens, and identifies body areas that should be targeted for delivery of repellents or acaricides.

Animals↗
PubMed1997

Density and distribution of cattle lice (Phthiraptera:Haematopinidae, Linognathidae, Trichodectidae) on six steers.

The density and distribution of four species of cattle louse, Bovicola bovis (L.). Haematopinus eurysternus (Nitzsch), Linognathus vituli (L.), and Solenopotes capillatus (Enderlein), were elucidated from the hides of six slaughtered steers. Adult and nymphal lice were first removed from one hide by hand and the location of each specimen mapped. The remaining lice were removed by a detergent wash, and KOH dissolution of hide and hair. Lice from the remaining five hides were removed using KOH dissolution of cattle hair and subsequent filtration of the effluent. Bovicola bovis was most abundant, followed by H. eurysternus, L. vituli and S. capillatus. Significant variation was observed in B. bovis, H. eurysternus and L. vituli population densities. Solenopotes capillatus population densities did not differ significantly. All species were contagiously distributed, i.e. 'clumped', suggesting species dependent predilection sites. Predilection sites were ranked according to louse density to facilitate the development of field sampling strategies. Additional biological data were gathered on sex and life stage ratios for each species.

Animals↗
PubMed1993

Egg yolk and bacteria growth medium for Musca domestica (Diptera: Muscidae).

Six preparations of egg yolk media inoculated with Escherichia coli (Migula) were evaluated as an in vitro growth system for immature house flies, Musca domestica L. Larval development, based on pupation and eclosion success, was normal on all media supplemented with E. coli, but few larvae survived without bacteria (4%). Pupation (72%) and eclosion (63%) were significantly higher on egg yolk media without mannitol than on media with mannitol or on blood agar controls.

Animals↗
PubMed1992

Evaluation of field propagation of Muscidifurax zaraptor (Hymenoptera: Pteromalidae) for control of flies associated with confined beef cattle.

The parasitic wasp Muscidifurax zaraptor Kogan & Legner was mass-reared in the field to control house flies, Musca domestica L., on two Nebraska beef cattle confinements. About 50,000 freeze-killed house fly pupae were exposed to a single release of M. zaraptor in the field. Placement of six additional cohorts of 50,000 freeze-killed pupae at the release sites at 2-wk intervals resulted in a mean parasite emergence of 56.4% over the study period. Mean fly mortality of 37.3 and 25.9% occurred in sentinel pupae placed around the perimeter of two release sites, compared with 3.9% for two control sites. We demonstrated a negative correlation between host reduction in sentinel cohorts and distances the cohorts were placed from parasite release sites. However, data indicated that other environmental factors also influenced the success of M. zaraptor in locating sentinel hosts. Correlation between mortality in sentinel pupae and numbers of parasites released was not evident. Temperatures above approximately 28 degrees C appeared to reduce the effectiveness of M. zaraptor.

Animals↗
PubMed1991

Seasonal movement and spatial distribution of the sheep ked (Diptera: Hippoboscidae) on Wyoming lambs.

When populations of adult sheep ked, Melophagus ovinus (L.), infesting unshorn lambs were monitored at the University of Wyoming Paradise Farm during 1986, we determined the body regions on which keds would be found at various times of the year and their seasonal population trends for optimal sampling. Results suggested that ked populations were consistently greater on the ribs than on any other area of the lamb. No significant differences were detected for ked populations between sides of a lamb. Distinct and similar ked population trends over time occurred only in the rib, thigh, shoulder, hind leg, belly, and hind flank areas of the lambs, suggesting that a significant seasonal migration did not occur. Analyses for seasonal population fluctuations indicated that ked populations increased in the winter and spring, decreased in summer and then increased again in the fall. Thus, sampling for keds in the rib area at shearing, which begins in March in Wyoming and runs through mid-April, would be an opportune time to detect keds. At other times of the year, the rib area should be inspected for presence of sheep ked.

Animals↗
PubMed1991

Infectivity of Serratia marcescens (Eubacteriales: Enterobacteriaceae) in Stomoxys calcitrans (Diptera: Muscidae).

Serratia marcescens Bizio, a facultative pathogen of insects, was isolated from stable flies, Stomoxys calcitrans (L.), collected from Nebraska beef cattle feedlots and dairies. Infection rates in laboratory-reared stable flies infected by topical exposures to the bacterium were 57 and 64% in two experiments. Per os exposures to sucrose and water solutions, and bovine blood inoculated with S. marcescens, produced mortality rates of about 45 and 10%, respectively.

Animals↗
PubMed1989

Monoclonal antibodies directed against basic fibroblast growth factor which inhibit its biological activity in vitro and in vivo.

A panel of four murine monoclonal IgG1 antibodies (mAbs) to a recombinant form of basic fibroblast growth factor (bFGF) was produced using somatic cell fusion techniques. Non-linear regression analysis of radioimmunoassay data for each mAb yielded the following dissociation constants (nM) for their interactions with bFGF: DE6 (0.822); AF11 (2.0); FE8 (2.31); and DG2 (20.0). One of the mAbs, DG2, was identified as a bFGF neutralizing antibody on the basis of its ability to inhibit, in vitro, the binding of [125I]-bFGF to high and low affinity bFGF sites on cultured baby hamster kidney cells and bFGF-induced [3H]-thymidine incorporation in cultured 3T3 cells, and in vivo, the angiogenic response to bFGF in a rat kidney capsule model of angiogenesis. The other mAbs displayed varying inhibitory activities in these assays. These mAbs, particularly DG2, may be well suited for a number of applications in bFGF research including immunoassays, immunohistochemical studies, and as functional antagonists of bFGF for examining its role in physiological processes such as reproduction, growth, and development.

Animals↗
PubMed1989

Initial drinking experiences among black and white male and female student drinkers.

Survey studies have revealed significant gender and racial differences in alcohol use patterns. One variable which may be related to some of these differences is initial drinking experiences. In this study, such experiences were assessed among 96 Black and White male and female college students. Consistent with past research, differences in initial drinking experiences were associated with gender. Predominant was the finding that men drank more during their initial drinking experience than did women. Further, males tended to report a shorter latency before the second drinking occurrence than did females, and females were more likely to first drink with family while males more often first drank with friends. No racial differences were found. Differences in later drinking patterns, especially those correlated with race, may depend more on subsequent rather than initial drinking experience.

Adult↗
PubMed1988

Racial factors influencing college students' ratings of alcohol's usefulness.

Efforts to understand alcohol use and abuse among young adults necessarily require attention to drinkers' motivations to drink. In the present study, dose-related reasons for drinking were assessed to determine the extent to which expected effects of alcohol are correlated with race and gender among college students. A consistent association between endorsements of alcohol's usefulness (i.e., Useful for Feeling Better, Useful for Feeling in Charge, Useful for Relieving Emotional Distress) and race, gender, and volume of alcohol rated was found. In particular, black female college students (relative to white females and black males) tended to ascribe much stronger utility to higher amounts of alcohol. A similar tendency was found for white males relative to white females. There were few group differences on usefulness ratings provided for lower amounts of alcohol. These findings indicate that the perceived usefulness of alcohol in this population of college students varies considerably according to race, gender and amount of alcohol, with the effects pronounced among black females.

Adult↗
PubMed1986

Effects of expanded tobacco on acceptability and reported consumption of low-tar cigarettes.

Experimental cigarettes designed for the low-tar band were made from one of two blends of tobacco and either 10% or 25% of expanded tobacco. They were smoked over a 7-day period by 24 habitual smokers of cigarettes in the middle-tar band. Sensory characteristics and acceptability of the cigarettes were assessed at first presentation, after 3 days and again at the end of the trial. The expanded-tobacco cigarettes were judged to be weaker than the smokers' own usual brands, and the 25% weaker than the 10% expanded. However, perceived strength increased over the 7-day trial. No effect of blend was detected. Smokers given cigarettes with 10% expanded tobacco smoked considerably more of them than was predicted from their reported normal consumption, but this sign of some compensation for reduced nicotine yield did not appear with 25% expanded tobacco. The implications are discussed for persisting smokers switching to the low-tar band, as officially advised to reduce health risks.

Adult↗
PubMed1983

Effects of carrier ampholyte contamination on the biological and biochemical properties of streptococcal pyrogenic exotoxin type C.

Three streptococcal pyrogenic exotoxins (SPEs), designated as SPE A, B, and C, have been purified and characterized. Routine purification of the SPEs includes the technique of isoelectric focusing. An earlier study showed that the removal of commercial carrier ampholytes (Ampholines) from SPE was difficult. The physiochemical properties of SPE C were previously reported; however, the SPE C preparation used in those experiments was contaminated with Ampholines. As an alternative to Ampholines, we used simple buffers to generate the isoelectric focusing pH gradient and used this SPE C in a comparative study to evaluate the effects of Ampholine contamination on the biological and biochemical properties of this toxin. We found that Ampholine contamination overestimates protein concentration; consequently, the biological activity of SPE C was actually greater than reported. The most serious effect of Ampholines in SPE C was on amino acid analysis. The presence of Ampholines causes an apparent increase in neutral amino acids and a decrease in basic amino acids.

Amino Acids↗
PubMed1982

Social influences on alcohol consumption by black and white males.

Thirty-two black and 32 white male normal drinkers participated in a beer taste test either simultaneously (co-action condition) with a heavy drinking black or white experimental accomplice or while the accomplice completed an art rating task (control observer condition). Subjects in the co-action condition drank significantly more beer (p less than .001) than subjects in the control observer condition, regardless of their race or the race of the accomplice. Subjects' post-experimental questionnaire answers indicated they did not perceive themselves to be in competition with the accomplice. The mechanism underlying the robust co-action facilitation effect on drinking, now demonstrated in several studies and extended to black males in the present study, remains unexplained.

Adolescent↗