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Biomedical subjects

D C Barrett

Publications and source records attributed to D C Barrett.

At least 19 recordsLinked to original sources
PubMed2005

Treatment of persistent intramammary infections with Streptococcus uberis in dairy cows.

A survey was conducted of the prevalence of environmental pathogens, especially Streptococcus uberis, as causes of clinical mastitis in dairy cows. The response of intramammary infections with S uberis to conventional treatment was monitored by taking milk samples for bacteriology and somatic cell counting seven, 14 and 21 days after the treatment. The results showed that 51 per cent of the infections failed to respond, and the odds of cases failing to respond was significantly increased when the individual quarter somatic cell count seven days after the treatment was greater than 201,000 cells/ml. Ninety-six per cent of the suspected S uberis isolates identified by culture were confirmed as S uberis by using the api 20 Strep system. Restriction endonuclease fingerprinting was used to type the strains of S uberis isolated from 75 milk samples from 32 cows. Analysis showed that 96 per cent of the cases of S uberis that failed to respond to conventional treatment were persistent infections with one strain rather than reinfections with different strains. The persistent cases of S uberis were treated further with an extended course of intramammary preparations containing either procaine penicillin with dihydrostreptomycin or cefquinome. There was no significant difference between the cure rates achieved by the two preparations, and 55 per cent of the cases that had failed to respond to conventional treatment responded to the additional treatment.

Animals↗
PubMed2004

Clinical and pathological features of dilated cardiomyopathy in Holstein-Friesian cattle.

Dilated cardiomyopathy is a primary disease of the heart muscle that has been reported in Holstein-Friesian cattle worldwide in the past 20 years. Nine cases of the condition were compared in terms of their clinical and pathological characteristics with nine unaffected animals matched for age, sex and breed. Their clinical signs included right-sided heart failure with severe subcutaneous oedema, ascites and/or hydrothorax and distended jugular veins. There were no characteristic biochemical or haematological changes. Postmortem, the affected hearts were enlarged with all the chambers dilated and walls of variable thickness. In most cases the kidneys were pale with a pitted surface. Histologically there was marked perimysial and endomysial fibrosis, extensive loss of cardiomyocytes by coagulative or colliquative necrosis, increased variation in the cross-sectional area of the myocardial fibres, and multifocal disarray and vacuolation of myocytes. Scanning electron microscopy showed that in all cases there was a mild myocardial inflammatory infiltrate, either diffuse or multifocal, which was identified by immunohistochemical labelling as T cells.

Age Factors↗
PubMed2003

Use of clinical information to predict the characteristics of bacteria isolated from clinical cases of bovine mastitis.

Farmers recorded the clinical signs of cows with clinical mastitis and submitted milk samples for bacteriological examination, so that the clinical signs could be correlated with the bacteriological findings. Odds ratios for the demeanour of the cow, the appearance of the milk, milk yield, udder texture, and the administration of parenteral antibiotics were calculated for mastitis cases classified in terms of their microbiology as either enterobacteriaceae, major Gram-positive pathogens, minor pathogens, 'no growths' or 'all other pathogens'. Animals infected with enterobacteriaceae had the highest odds of being reported as having a reduced milk yield, swollen or hard udders, watery milk and/or being systemically sick. A logistic regression model was used to predict the Gram-staining characteristics of the bacteria causing clinical mastitis. The clinical findings found to be significant predictors in the model were the demeanour of the cow and its milk yield. The regression model was used as a basis for a predictive test. Using a test data set, the sensitivity of the test was 28 per cent, its specificity was 96 per cent, the positive predictive value was 74 per cent and the negative predictive value was 80 per cent. The overall accuracy of these predictions was 79 per cent.

Animals↗
PubMed2001

Dissecting aneurysm of the carotid artery as a cause of respiratory distress in adult cattle.

A two-and-a-half-year-old Friesian cow and a five-year-old Charolais cow developed severe respiratory distress and palpable swellings to the left of the larynx as a result of a dissecting aneurysm of the common carotid artery. Neither cow responded to medical treatment. The underlying pathogenesis of the condition was uncertain, but direct trauma to the carotid artery was a possible contributory factor. Aneurysms of the common carotid artery should be considered when swelling occurs in the region of the larynx or when respiratory distress is due to laryngeal compression.

Aortic Dissection↗
PubMed2001

Observations on ascites in nine cattle.

Signs of ascites were observed in only nine of 1863 cattle examined over a period of five years. The ascites was most commonly associated with either primary or secondary cardiac disease; cattle with ascites have a poor prognosis because the condition is usually assocaited with terminal disease. Two animals had cor pulmonale with chronic pneumonia, three had cardiomyopathy, one had bacterial endocarditis, two had thrombosis of the caudal vena cava and one had diffuse abdominal epithelioid mesothelioma.

Animals↗
PubMed2000

Cost-effective antimicrobial drug selection for the management and control of respiratory disease in European cattle.

Respiratory disease in growing cattle has both animal welfare and economic implications, but the use of antimicrobial drugs to treat and control it is under public scrutiny owing to concerns that their use in food-producing animals may be detrimental to human health. This paper outlines criteria for the selection of appropriate and cost-effective drugs, based on good dinical practice and sound economic principles. It also suggests that these principles should be integrated into quality assurance schemes, and that the monitoring of antimicrobial resistance patterns among known bacterial respiratory pathogens should be improved.

Animals↗
PubMed2000

Substance use and HIV risk profile of gay/bisexual males who drop out of substance abuse treatment.

This analysis was undertaken to identify (a) the level of HIV sexual risk behaviors of men who drop out of treatment and (b) baseline variables associated with later treatment dropout. A cross-sectional sample of 340 gay/bisexual men were recruited from an outpatient substance abuse treatment facility in San Francisco. We compared participants who completed less than 15 visits with participants who graduated from the program. Men who dropped out were more likely than treatment graduates to report injection drug use, social problems related to substance use, self-blaming coping strategies, and more recent substance use prior to entering treatment and less likely to have a college degree, report using sex for tension relief, and have previously attended Alcoholics Anonymous or Narcotics Anonymous. Given the strong link between the substance abuse and HIV epidemics, substance abuse treatment agencies have been forced into addressing the issues of HIV sexual risk taking with their clients. Strategies toward reducing substance use relapse and HIV risk reduction are offered.

Adolescent↗
PubMed1999

An outcome evaluation to measure changes in sexual risk-taking among gay men undergoing substance use disorder treatment.

OBJECTIVE: To evaluate the effects of safe sex intervention at a substance use disorder treatment agency designed to serve gay men. METHOD: Of all eligible men, 456 (78%) were recruited as they entered treatment for a substance use disorder. This cohort was followed for five waves of data collection, each wave measuring the previous 90 days. Assigned to the experimental condition (treatment for substance use disorder plus a safe sex intervention) were 82 men; 65 were assigned to the regular substance use disorder treatment. RESULTS: Although levels of risk within each wave were never significantly different between the two treatment groups, reductions in unprotected anal intercourse (UAI) with a nonmonogamous partner for both groups from the baseline Wave-1 levels were uniformly significant (all p's < .05). Such high-risk sex in the year-long follow-up period was correlated with UAI reported at intake, enjoyment of UAI, relative youth, heavier concurrent use of alcohol or amphetamines and greater numbers of sexual partners. CONCLUSIONS: We conclude that: (1) substantial HIV risk reductions can occur after initiation of treatment for substance use disorder among gay men; (2) risk reductions begin soon after treatment begins; (3) lapses to unsafe sex are common during treatment; (4) continued UAI is most likely among those men who are riskier at intake, who continue to be more sexually active and who are more likely to combine substance use and sexual behavior; (5) AIDS prevention activities conducted at treatment agencies cannot reach all high-risk substance-using gay men.

Adolescent↗
PubMed1998

Alcohol and drug use patterns have declined between generations of younger gay-bisexual men in San Francisco.

OBJECTIVES: To describe changes in alcohol and drug use between two independent samples of gay-bisexual men aged 25-29. METHODS: Comparisons between the 1984 San Francisco Men's Health Survey (SFMHS) and the 1992 San Francisco Young Men's Health Survey (SFYMHS). RESULTS: Heaviest levels of alcohol use decreased between the 1984 and 1992 samples as did most types of drug use, with the exception of an increase in the use of MDA. CONCLUSIONS: Important declines in heavy alcohol use and overall drug use occurred among young gay men between 1984 and 1992. However, levels of substance use still remain high and may constitute a continued threat to the health of gay-bisexual men.

Adult↗
PubMed1998

Risk factors for repeated gonococcal infections: San Francisco, 1990-1992.

Gonococcal (GC) infections are very common and are sustained by a core group of persons who often have repeated GC infections. Identifying individual risk factors for repeated GC infection is essential so that infection control programs can develop better strategies for decreasing the incidence of GC infection. A case-control study among high-risk persons found that being African American, having previous chlamydia infection, and having less than a high-school education were associated with repeated GC infections. Remarkably, measures of sexual behavior and access to health care were not associated with repeated GC infections. These findings suggest that among high-risk persons, the community prevalence of GC infection is more important in predicting risk for repeated GC infections than individual behavior. Interventions should include continued use of resources in high-prevalence communities and better understanding of the roles social and economic discrimination play in the risk for GC infections.

Adolescent↗
PubMed1998

Self-reports of alcohol use, drug use and sexual behavior: expanding the Timeline Follow-back technique.

OBJECTIVE: The purpose of this study is to compare reports of alcohol use, drug use and sexual behavior from 30-day Summary measures with an expanded version of a Timeline Follow-back (Timeline) interview technique among gay/bisexual men entering outpatient substance abuse treatment at a gay-identified agency. METHOD: Respondents (N = 418) first completed self-administered questionnaires covering the 30-day period prior to their last use of alcohol or drugs. Summary measures included alcohol use, number of days of use for five categories of drugs and number of episodes of anal intercourse (with and without condoms) by partner type (primary or secondary). Participants then completed the Timeline interview procedure to recall their daily drinking, drug use and sexual behavior during the same 30-day period. RESULTS: The findings indicate that the Timeline method yielded significantly lower estimates of mean number of drinks consumed when heavier than usual drinking days is included in the Summary measure (124.0 vs 147.0 drinks), mean number of days drugs were used (9.3 vs 10.7) and mean number of episodes of anal intercourse with a primary partner (1.2 vs 2.2). Differences generally remained significant when assessed by length of time between the study interview and last use of alcohol or drugs, with the exception of number of anal sex episodes with primary partners. CONCLUSIONS: These findings indicate that Timeline estimates are lower than estimates using a more standard method (Summary measures). Discrepancies between these findings and those reported by other researchers indicate a need for further exploration of the effects of the mode of administration on various populations.

Adult↗