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J Stephenson

Publications and source records attributed to J Stephenson.

At least 145 records · Page 8Linked to original sources
PubMed1999

Influence of body condition score on by-product yield and value from cull beef cows.

Mature beef cows (n = 122) representing British and Continental phenotypes were slaughtered to measure the influence of body condition score (BCS) on by-product yield and value. All cows were weighed and assigned BCS, based on a 9-point scale, 24 h before slaughter. By-product weights were obtained during the slaughter process and included blood, feet (with hooves attached), oxlips, tongue, gullet, trachea, cheek meat, head meat, skull, tripe, honeycomb tripe, large and small intestines, spleen, mesenteric fat, weasand meat, kidneys, heart, lungs, and oxtail. By-product yields were calculated as a percentage of the animal's live weight taken 24 h before slaughter. By-product values were computed by multiplying the weight of each piece removed during the slaughter process by the 1997 average price. Live weight increased linearly (P<.001) as BCS increased from 2 to 8, whereas Continental cows were approximately 86 kg heavier (P<.05) at slaughter than British cows. Cows assigned a BCS of 2 or 3 had greater (P<.05) skull, feet, tongue, tripe, honeycomb tripe, trachea, and lung yields than cows assigned a BCS of 4 or higher. On the other hand, BCS-7 and 8 cows had greater (P<.05) weights and yields of large intestines and mesenteric fat than cows given a BCS of 6 or lower. The feet, trachea, lungs, and bone meal from BCS-2 cows had the greatest (P<.05) value, whereas the value of the large intestine, oxtail, and mesenteric fat was highest (P<.05) for BCS-7 and 8 cows. Weight, yield, and value of the skull, head meat, and feet were greater (P<.05) for Continental cows than British cows. Total by-product value was quadratically (P<.001) related to BCS. Cows assigned a BCS of 5 had lower (P<.05) total by-product values than either BCS-2 or BCS-7 and 8 cows. Drop credit for BCS-2 cows was greater (P<.05) than BCS-3, 4, 5, and 6 cows, with cows assigned a BCS of 7 and 8 having intermediate drop credit values. Continental cows tended to have greater (P<.10) total by-product and drop credit values than British cows. Information from this study indicated that the BCS of cows at the time of slaughter had a profound influence on by-product yields and, more importantly, values of by-products that are credited back against the cost of production to the beef cattle producer.

Animal Husbandry↗
PubMed1999

Risk factors for tuberculosis in patients with AIDS in London: a case-control study.

OBJECTIVE: To identify risk factors for the acquired immune-deficiency syndrome (AIDS) associated with tuberculosis, in patients with AIDS attending 11 of the largest human immunodeficiency virus (HIV)/AIDS Units in London. DESIGN: Case-control study nested in a retrospective cohort of 2048 HIV-1 positive patients. Cases were defined as patients with a definitive diagnosis of tuberculosis, and controls as patients with AIDS and without tuberculosis during follow-up. RESULTS: Of 627 patients diagnosed with AIDS, 121 had a definitive diagnosis of tuberculosis. Significant risk factors for tuberculosis in the univariate analysis were sex, ethnicity, age, HIV exposure category and hospital attended, and in the multiple regression analysis ethnicity, age and hospital attended. African ethnicity was the strongest risk factor for tuberculosis (adjusted odds ratio [AOR] 5.9, 95% confidence interval 3.4-10.2). The risk of tuberculosis was higher in the younger age groups (test for trend P < 0.001). The hospital-associated risk of tuberculosis was more heterogeneous in the non-African group, and non-Africans attending Hospital 1 had an increased risk of tuberculosis which was statistically significant. CONCLUSIONS: The risk factors for AIDS-associated tuberculosis in London are sub-Saharan African origin, younger age group, and, among the non-Africans only, attending one hospital in east London. Different transmission patterns and mechanisms for the development of tuberculosis may operate in different settings depending on the background risk of tuberculous infection. Screening for tuberculosis infection and disease among HIV-positive individuals in London is important for the provision of preventive or curative therapy, and prophylaxis policies need to be designed in accordance with the transmission patterns and mechanisms of disease.

Acquired Immunodeficiency Syndrome↗
PubMed1998

The relationship of HIV prevalence in pregnant women to that in women of reproductive age: a validated method for adjustment.

OBJECTIVE: To devise and validate a method for adjusting HIV seroprevalences in pregnant women to estimate population prevalences among all women in their child-bearing years. DESIGN: Birth and termination rates from women with known HIV infection in the United Kingdom were calculated according to the likely route of HIV infection and whether HIV infection was diagnosed. METHODS: Birth and termination rates were weighted and combined to produce summary statistics. Comparisons were then made with population birth and termination rates to derive summary relative inclusion ratios (RIRs), the relative probabilities of including HIV-infected and uninfected women in seroprevalence surveys of pregnant women. RESULTS: The derived RIRs for women having live births were close to unity: 1.03 [95% confidence intervals (CI) 0.90-1.17] for London and 0.80 (Cl, 0.71-0.89) for elsewhere in England and Wales. This indicates that currently observed overall seroprevalences among pregnant women having live births in London would be similar to those among all women of the same age, while elsewhere it would be slightly underestimated. Sensitivity analysis indicated that RIRs could, however, vary three-fold (0.47-1.56) according to the proportion of diagnosed maternal infections and the mix of maternal HIV-exposure categories. The method was validated by using it to predict the ratio of unlinked seroprevalences between women having terminations and live births in London. It predicted a ratio of 1.74: 1, which is close to the observed ratio of 2.07 : 1. CONCLUSIONS: Application of HIV seroprevalences from pregnant women to whole populations may need adjustment for fertility rates among HIV-infected women. A general method for this has been derived and validated. Gathering fertility data for HIV-infected women is a useful adjunct to serosurveillance.

Birth Rate↗
PubMed1998

Defective adenoviruses as novel vaccines for the Flaviviridae.

BACKGROUND: Vaccines against many flaviviruses, such as Japanese encephalitis virus (JEV), yellow fever virus (YFV) and tick-borne encephalitis virus (TBEV), have been successfully used for many years. Other diseases such as dengue fever (DF) and hepatitis C are still major public health problems as no licensed vaccines are in use. OBJECTIVES: To review studies on the use of defective recombinant adenoviruses (Rads) as experimental flavivirus vaccines and comment on their use to prevent infections with other members of the Flaviviridae such as hepatitis C virus. STUDY DESIGN: Recombinant adenoviruses, defective in their replication strategy, contain deletions in the E1 and E3 regions of the genome to increase the amount of foreign genetic material that can be inserted. The expression of foreign genes, inserted into these regions, can be driven by the adenovirus's own promoter, or by an additional viral promoters. CONCLUSIONS: Rads have been successfully used to raise protective immunity in experimental models of infection with several viruses. They can elicit both humoral and cell-mediated immunity and can be given parenterally or by oral administration. In addition, their hepatotropism makes them suitable for tackling diseases such as hepatitis C. Careful design of the vaccine vectors is advised to ensure their efficacy and safety, and as hepatitis C is a persistent infection, it may be advisable to design Rads containing genes encoding for non-structural proteins in preference to structural proteins.

Adenoviridae↗
PubMed1998

Disease progression and survival in HIV-1-infected Africans in London.

OBJECTIVE: To examine differences in progression to AIDS and death between HIV-1-positive Africans (most infected in sub-Saharan Africa and therefore with non-B subtypes) and HIV-1-positive non-Africans in London. DESIGN: Retrospective cohort study of 2048 HIV-1-positive individuals. SETTING: HIV-1-infected individuals attending 11 of the largest HIV/AIDS units in London. PATIENTS: Subjects were 1056 Africans and 992 non-Africans seen between 1982-1995. RESULTS: There were no differences in crude survival from presentation to death between Africans and non-Africans (median 82 and 78 months, respectively; P = 0.22). Africans progressed more rapidly to AIDS [hazard ratio (HR), 1.21; 95% confidence interval (CI), 1.02-1.45] but after adjustment for age, sex, Centers for Disease Control and Prevention category B symptoms and CD4+ lymphocyte count at presentation, year of HIV diagnosis and hospital attended, this difference was no longer significant (adjusted HR, 1.15; 95% CI, 0.93-1.43). Africans with AIDS had a reduced risk of death compared with non-Africans (HR, 0.78; 95% CI, 0.63-0.96) but not after adjustment for age, CD4+ lymphocyte count at AIDS, initial AIDS-defining conditions (ADC) and hospital attended (HR, 0.98; 95% CI, 0.76-1.27). Tuberculosis as the first ADC was associated with a 64% reduction in the risk of death. CD4+ lymphocyte decline was not significantly different between Africans and non-Africans (P = 0.18). CONCLUSIONS: Differences in progression to AIDS and death and CD4+ lymphocyte decline between HIV-1-infected Africans and non-Africans in London could not be attributed to ethnicity or different viral subtypes. Age and the clinical and immunological stage at presentation, or AIDS, were the major determinants of outcome. Compared with other diagnoses, tuberculosis as the initial ADC was associated with increased survival. Lack of access to health care and exposure to environmental pathogens are the most likely causes of reduced survival with AIDS in Africa, rather than inherently different rates of progression of immune deficiency due to racial differences or viral subtypes.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Disease progression and survival following specific AIDS-defining conditions: a retrospective cohort study of 2048 HIV-infected persons in London.

OBJECTIVE: To assess the impact of specific AIDS-defining conditions on survival in HIV-infected persons, with emphasis on the effect of tuberculosis. METHODS: A retrospective cohort analysis of HIV-infected Africans and non-Africans attending 11 specialist HIV/AIDS units in London enrolled for a comparison of the natural history of HIV/AIDS in different ethnic groups. RESULTS: A total of 2048 patients were studied of whom 627 (31%) developed 1306 different AIDS indicator diseases. Pneumocystis carinii pneumonia accounted for 159 (25%) of initial AIDS episodes and tuberculosis for 103 (16%). In patients with HIV disease, tuberculosis had the lowest risk [relative risk (RR), 1.11; 95% confidence interval (CI), 0.75-1.63], and high-grade lymphoma had the highest risk (RR, 20.56; 95% CI, 2.70-156.54) for death. For patients with a prior AIDS-defining illness, the development of subsequent AIDS indicator diseases such as Pneumocystis carinii pneumonia (RR, 1.18; 95% CI, 0.77-1.83) and tuberculosis (RR, 1.36; 95% CI, 0.76-2.47) had the best survival, and non-Hodgkin's lymphoma had the worst survival (RR, 9.67; 95% CI, 1.26-74.33). Patients with tuberculosis had a lower incidence of subsequent AIDS-defining conditions than persons with other initial AIDS diagnoses (rate ratio, 0.47; 95% CI, 0.37-0.59). CONCLUSIONS: Considerable variation exists in the relative risk of death following different AIDS-defining conditions. The development of any subsequent AIDS-defining condition is associated with an increased risk of death that differs between diseases, and this risk should be considered when evaluating the impact of specific conditions. Like other AIDS-defining conditions, incident tuberculosis was associated with adverse outcome compared with the absence of an AIDS-defining event, but we found no evidence of major acceleration of HIV disease attributable to tuberculosis.

AIDS-Related Opportunistic Infections↗