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Biomedical subjects

S J Wells

Publications and source records attributed to S J Wells.

At least 37 records · Page 2Linked to original sources
PubMed2000

Fecal shedding of Campylobacter and Arcobacter spp. in dairy cattle.

Campylobacter jejuni, Campylobacter coli, and Arcobacter spp. were detected in feces of healthy dairy cows by highly specific multiplex-PCR assays. For C. jejuni, at this one-time sampling, cows from 80.6% of farm operations (n = 31) and 37.7% of individual dairy cattle fecal samples (n = 2,085) were positive. Farm management factors were correlated with prevalence in herds in which >25% of cows were positive for C. jejuni. Statistical significance was set at a P of 0.20. Using these criteria, application of manure with broadcast spreaders (P = 0.17), feeding of whole cottonseed or hulls (P = 0.17) or alfalfa (P = 0.15), and accessibility of feed to birds (P = 0.17) were identified as possible risk factors for C. jejuni infection. C. coli was detected in at least one animal in 19.4% of operations and 1.8% of individual cows (n = 2,085). At the herd level, use of broadcaster spreaders was not a risk factor for C. coli infection. For Arcobacter, cows from 71% of dairy operations (n = 31) and 14.3% of individual dairy cattle fecal samples (n = 1,682) were positive. At the herd level, for Arcobacter spp., feeding of alfalfa (P = 0.11) and use of individual waterers (P = 0.19) were protective. This is the first description of Arcobacter spp. in clinically healthy dairy cattle and the first attempt to correlate their presence with C. jejuni.

Animal Feed↗
PubMed2000

Biosecurity on dairy operations: hazards and risks.

The objective here was to present a model for considering biosecurity related to infectious diseases on US dairy operations using a risk assessment framework. With the example of an important dairy cattle pathogen (Mycobacterium paratuberculosis), I followed risk assessment steps to characterize risks related to the use of certain management practices and possible risk reduction within an infectious disease biosecurity program. Biosecurity practices focus on the prevention of introduction of these pathogens to the dairy, and estimates of the risks associated with introduction of different sources of cattle are presented. In addition, biosecurity practices also limit the transmission of these pathogens within an infected dairy operation, especially those focused on sick cow management, calving area management, and manure management. Recent information from the National Animal Health Monitoring System (NAHMS) Dairy 96 Study indicates that many of these practices have not been adopted on US dairy operations, indicating both risk of disease and opportunity for animal health improvement.

Animal Husbandry↗
PubMed1999

Herd-level economic losses associated with Johne's disease on US dairy operations.

Johne's disease ('paratuberculosis') is a chronic, infectious, wasting disease that affects dairy cattle. Estimation of its impact on herd productivity and corresponding economic loss on US dairy operations was part of the USDA National Animal Health Monitoring System's (NAHMS) 1996 national dairy study. Johne's-positive herds experience an economic loss of almost US$ 100 per cow when compared to Johne's-negative herds due to reduced milk production and increased cow-replacement costs. For Johne's-positive herds that reported at least 10% of their cull cows as having clinical signs consistent with Johne's disease, economic losses were over US$ 200 per cow. These high-prevalence herds experienced reduced milk production of over 700 kg per cow, culled more cows but had lower cull-cow revenues, and had greater cow mortality than Johne's-negative herds. Averaged across all herds, Johne's disease costs the US dairy industry, in reduced productivity, US$ 22 to US$ 27 per cow or US$ 200 to US$ 250 million annually.

Animals↗
PubMed1999

Papillomatous digital dermatitis and associated risk factors in US dairy herds.

The objective of this study was to describe the incidence of papillomatous digital dermatitis in the US (including regional and herd size patterns) and to evaluate specific herd-level management factors associated with high incidence of digital dermatitis in US dairy herds. The study design was a population-based cross-sectional survey. US dairy operations with at least 30 cows in 20 states, representing 79% of US dairy cows, were sampled. On participant operations, a questionnaire was administered by veterinary medical officer or animal-health technicians on-farm to dairy managers. Papillomatous digital dermatitis was reported in milk cows in the previous 12 months from 43.5% of US dairy herds. Seventy-eight percent of affected herds reported that their first cases occurred in 1993 or later. Regions of the USA with the highest percent of herds affected included the Southwest, Northwest, and Northeast. Factors associated with high (> 5%) incidence of papillomatous digital dermatitis included region, herd size, type of land lactating cows accessed on a daily basis, flooring type where lactating cows walked, percent of cows born off the operation, use of a primary hoof trimmer who trimmed cows' hooves on other operations, and lack of washing of hoof-trimming equipment between cows. Papillomatous digital dermatitis has been recently reported from dairy herds across the US. This study suggests that a high percentage of herds with digital dermatitis could be prevented. Management strategies to potentially prevent or reduce incidence of digital dermatitis on dairy operations include those related to biosecurity and 'cow hoof' environmental conditions.

Animals↗
PubMed1999

Syphilitic lymphadenopathy. Histology and human immunodeficiency virus status.

Few reports on syphilitic lymphadenopathy have appeared in 20 years, and none have compared findings in patients with and without human immunodeficiency virus (HIV) infection, despite the recent epidemic spread of syphilis and HIV. Twelve cases of syphilitic lymphadenopathy were studied and grouped according to HIV status. Patients were 21 to 62 years old (median, 29 years); 7 were men, 5 were women. Biopsy sites were cervical (7 cases), inguinal (4), and axillary (1) lymph nodes. All patients had evidence of syphilis. Rapid plasma reagin titers ranged from 1:32 to 1:512. Treponemal hemagglutination was positive in all cases tested. Spirochetes were found with Steiner staining in 2 cases. HIV testing was positive in 4, negative in 2, and unknown in 6 cases. Lymph nodes were enlarged and often fragmented due to capsular fibrosis and chronic inflammation, with focal obliteration of the subcapsular sinus. Follicular and interfollicular hyperplasia was seen in all cases and was usually marked, with prominent vascular proliferation, plasma cells, immuno-blasts, histiocytes, and occasional neutrophils. Follicle lysis and granulomas suggestive of unconfirmed toxoplasmosis were each seen in 1 case, and Kaposi sarcoma in 2, all in HIV-positive patients. Lymphoplasmacytic infiltration was marked, especially in interfollicular areas, with peri-vascular plasma cell cuffing in all cases and obliterative endarteritis in about half (7 of 12, 56%). Immunostaining for CD45RO (UCHL-1), CD20 (L26), kappa, lambda, and CD68 (Kp-1) revealed a mixed population of T cells, polyclonal B cells, and interfollicular histiocytes. Distribution of T and B cells (immunoarchitecture) was essentially normal and similar in all cases, regardless of HIV status. Syphilis produces essentially identical findings in lymph nodes in both HIV-positive and HIV-negative patients. The morphologic findings described should prompt evaluation for infection with Treponema pallidum and, in light of the current epidemic, HIV.

Adult↗
PubMed1998

Factors in the emergence of food borne diseases.

Food borne diseases are an important public health problem. Over the past two decades, the epidemiology of food borne diseases has changed rapidly as a consequence of changes in the social environment and the ability of pathogens to adapt to new niches. Several newly recognized pathogens have emerged and well-recognized pathogens have increased in prevalence or become associated with new food vehicles. Several factors have contributed to the changing patterns of food borne diseases, and addressing food borne diseases will require rapid surveillance and effective prevention strategies. This article examines these factors and briefly addresses prevention and control of food borne diseases.

Adaptation, Biological↗
PubMed1998

Genetic analysis of clinical lameness in dairy cattle.

Scores for clinical lameness from two separate studies were combined, and genetic parameters were estimated based on linear and threshold models. Cows were from 24 herds in Minnesota, Wisconsin, and Virginia. To evaluate clinical lameness, cows were observed walking and were assigned a score between 0 and 4 (where 0 = no observable problems to 4 = inability to walk). Data included 1624 records on 1342 cows. The models included fixed effects of herd visit, parity, and stage of lactation. Random effects were additive genetics, permanent environment to account for repeated records, and residual. Estimates of heritability were 0.10 and 0.22 from the linear and threshold models, respectively. The correlation between ETA from linear and threshold models based on all animals was 0.974. Deregressed ETA of sires and REML were used to estimate genetic correlations between clinical lameness and conformation traits. Among the type traits, foot angle, rear legs (rear view), and rump width had strongest associations with clinical lameness; absolute values for genetic correlations between these traits and clinical lameness were approximately 0.65. Low foot angle, hocking in, and wide rumps were associated with increased clinical lameness. Correlations with strength and body depth ranged from 0.20 to 0.43, indicating that heavier cows were more prone to clinical lameness.

Animals↗
PubMed1998

Key health issues for dairy cattle--new and old.

The objective of this paper is to use available information to evaluate the relative importance of various health issues affecting dairy cattle. In addition to traditional ranking using evaluation methods based on impacts to animal productivity, this paper considers zoonotic risks, international trade implications, and animal welfare concerns. Traditional production costs rank mastitis, reproductive problems, and lameness as the top dairy cattle diseases. When the other areas of importance are included, the top-ranked diseases change to include salmonella, Johne's disease, bovine viral diarrhea-associated disease, and mastitis. Researchers in the dairy industry may want to reevaluate their criteria for setting research priorities to include zoonotic risks, international trade implications, and animal welfare concerns.

Animal Welfare↗
PubMed1997

Health status of preweaned dairy heifers in the United States.

The first national estimates of mortality and morbidity for preweaned dairy heifers in the US were generated from monitoring heifers from 906 operations in 28 states prospectively using a daily diary card system. Results indicated that the cumulative mortality incidence risk from birth to 8 weeks of life was 6.3% with a peak of 1.9% during the first week of life. Season of birth was significantly associated with cumulative mortality incidence risk, and mortality risk was highest in the periods January to March and October to December. Cumulative incidence risk of diarrhea to 8 weeks of age was 24.6% with a peak of 15.4% during the second week of life. Diarrhea incidence risk varied by region, with the West having the highest incidence risk (30.5%) and the Northeast the lowest (19.2%), as well as by herd size, with the smallest herd size having the lowest reported incidence risk of diarrhea to 8 weeks of age (18.8%). Other reported 8 week cumulative disease incidence risks included listlessness, 10.0%; respiratory disease, 8.4%; dehydration, 4.1%; lameness or joint problems, 1.1%.

Aging↗
PubMed1997

Pediatric morning report: an appraisal.

We examined and contrasted morning reports at two hospitals, university and community, that have a pediatric residency program. Patient diagnoses assigned at morning report were compared with final diagnoses to assess disease categories discussed and the value of including outpatient follow-up in this educational forum. Data were obtained during morning reports for 6 months by chief residents at university and private community hospitals. Pertinent history, physical examination, and laboratory and radiologic findings were recorded and were assigned a tentative morning report diagnosis based on morning report discussion. Cases were then reviewed at discharge and at 6 months to determine final diagnoses. At the university hospital, 58% of the cases were undiagnosed before presentation at morning report. Of those cases, 23% were assigned a diagnosis at morning report that differed from the final diagnosis. Similarly, at the private community hospital, 28% of cases were undiagnosed before presentation at morning report. Of those cases, 73% were assigned a diagnosis that differed from the final diagnosis. We conclude that the provision of follow-up at morning report is important for maximizing resident education.

Child↗
PubMed1996

Image cytometric comparison of proliferating cell nuclear antigen and MIB-1 staining in hepatocellular carcinoma and adjacent liver tissue.

Studies of cellular proliferation may aid in elucidation of mechanisms of hepatocarcinogenesis and provide potential prognostic information in cases of hepatocellular carcinoma. Increased proliferation has been reported in the liver tissue adjacent to hepatocellular carcinoma and may be a risk factor for recurrence after tumor resection. We quantitated proliferating cell nuclear antigen (PCNA) clone PC10 and MIB-1 nuclear immunostain by image cytometry in fixed, paraffin-embedded tissue sections of normal, cirrhotic, and dysplastic livers with and without co-existent hepatocellular carcinoma and in the hepatocellular carcinoma. Fifteen high power fields were analyzed in each case using the CAS 200 image analyzer and results were expressed as the percent positive nuclear area. Cirrhotic liver showed significantly less proliferation adjacent to hepatocellular carcinoma than without hepatocellular carcinoma. There was a similar, but not significant, tendency for dysplastic liver. Increasing mean proliferation was noted from normal to cirrhotic to dysplastic liver to low grade to high grade hepatocellular carcinoma. These findings were similar using both PC10 and MIB-1. There tended to be slightly more staining with PC10 than with MIB-1, but the mean percent positive nuclear area was significantly greater with PC10 only in high grade hepatocellular carcinoma. Comparison of individual cases, however, yielded significant correlation between the two antibodies in the low grade and high grade hepatocellular carcinomas, but not in the benign livers. These findings demonstrate that image cytometric quantitation of PC10 and MIB-1 immunostain may be comparable measures of cellular proliferation and that there is no increase in proliferation in the hepatic tissue adjacent to hepatocellular carcinoma.

Antibodies, Monoclonal↗
PubMed1996

Reverse transcriptase-polymerase chain reaction for bcr/abl fusion in chronic myelogenous leukemia.

Reverse transcriptase-polymerase chain reaction (RT-PCR) has shown promise as a means of detecting low levels of cells bearing the Philadelphia chromosome (Ph1) and for detecting cytogenetically inapparent ("masked") Ph1 in patients with chronic myelogenous leukemia (CML). For detection by karyotyping, dividing cells must be used, precluding use of peripheral blood samples in cases with low peripheral blood blast counts. Reverse transcriptase-polymerase chain reaction was performed in 83 bone marrow and 30 peripheral blood samples from patients with CML to compare results with karyotyping and to evaluate utility of this test on peripheral blood samples. Using isolated total cellular RNA and a single primer pair, cDNA was transcribed, amplified, electrophoresed, and probed for bcr/abl fusion involving M-bcr exons 2 and 3 of the bcr gene. Fifty-three samples were from untreated or conventionally treated patients (pre-BMT), and 60 were from patients who had undergone bone marrow transplantation (post-BMT). Fifty of 53 pre-BMT samples were positive by RT-PCR. Two samples, negative by RT-PCR, had complex translocations, t(9;16;22) and t(4;14;22). One case was indeterminate by RT-PCR, but positive on retesting. Forty-five of 53 had Ph1 by karyotyping; 8 were negative, including 5 peripheral blood samples, 2 bone marrow samples with "masked" Ph1, and 1 bone marrow sample with poor growth. Thirty-five of 60 post-BMT samples were positive by RT-PCR. Fourteen of 60 post-BMT samples had Ph1 by karyotyping. Of the RT-PCR+/Ph1- cases, most showed a weak but definite band by RT-PCR, suggesting a low level of the bcr/abl fusion gene. Nineteen patients had concurrent peripheral blood and bone marrow samples analyzed by RT-PCR and karyotyping. Of 16 patients with satisfactory RNA extraction, 15 had concordant results by RT-PCR. Five patients had adequate metaphase cells for karyotypic analysis. All had Ph1 in bone marrow, but were negative in peripheral blood. Our results indicate that RT-PCR for detection of bcr/abl fusion is more sensitive than karyotyping in pre- and post-BMT samples. Furthermore, RT-PCR can be successfully performed on peripheral blood, yielding excellent correlation with bone marrow samples.

Base Sequence↗
PubMed1996

CD117/CD34 expression in leukemic blasts.

CD117 is a transmembrane protein receptor encoded by the c-kit proto-oncogene. The CD117 ligand is stem cell factor, an important hematopoietic regulator. CD117 is present on approximately 4% of normal bone marrow mononuclear cells and in acute myelogenous leukemia (AML) and chronic myelogenous leukemia in myeloid blast crisis, but rarely in acute lymphoblastic leukemia (ALL). Initially viewed as a primitive myeloid marker, CD117 has been identified in all FAB subtypes of AML and may predict poor outcome. CD34, a primitive stem cell marker, may also predict poor outcome. The aim of this study was to examine the relationship between CD117 and CD34 expression on leukemic blasts and to determine whether CD117 is related to lymphoid-associated antigen (LAA) expression in AML. Consecutive bone marrow samples were studied from cases of AML (30 cases), myelodysplastic syndromes (MDS) (4 cases), myeloproliferative disorders in blast crisis (MPD-BC) (6 cases), and ALL (5 cases). Cases were diagnosed according to FAB criteria and included M0 (3 cases), M1 (2 cases), M2 (13 cases), M3 (1 case), M4 (6 cases), M5 (3 cases), M6 (1 case), AML NOS (1 case), RAEB (3 cases), and RAEB-T (1 case). CD117 and CD34 were analyzed by multiparameter flow cytometry. Blasts in 10 de novo AML samples were CD117+/CD34+ in 4 cases, CD117+/CD34-in 3 cases, CD117-/CD34+ in 1 case, and CD117-/ CD34- in 2 cases. Blasts in 20 cases of relapsed AML were CD117+/ CD34+ in 13 cases, CD117+/CD34- in 6 cases, and CD117-/CD34+ in 1 case. Blasts in MDS were CD117+/CD34+ in 3 cases, CD117-/ CD34+ in 1 case. Blasts in MPD-BC were CD117+/CD34+ in 4 cases, CD117-/CD34+ in 2 cases. Blasts in ALL were CD117+/CD34+ in 1 case, CD117-/CD34+ in 1 case, CD117-/CD34- in 3 cases. Of 26 cases of CD117+ AML, CD4 was expressed in 15 (58%) cases, CD7 in 7 (27%) cases, and CD2 in 2 (8%) cases. CD117/CD34 expression did not correlate with FAB subtype of AML. CD117 is borne on most leukemic blasts of myeloid origin (in this study, 87% of AML, 80% of MPD-myeloid BC, and 75% of MDS) and does not exclude expression of LAA. Although CD117 is a receptor for stem cell factor, its expression does not appear to correlate with CD34 positivity.

Adolescent↗
PubMed1995

Risk factors for fecal shedding of Escherichia coli O157:H7 in dairy calves.

A case-control study was conducted to determine risk factors for fecal shedding of Escherichia coli O157:H7 (ECO) in dairy calves. Three herds previously found to lack calves that shed ECO in their feces were selected for each herd previously found to have calves that shed ECO. Fecal samples from 965 calves on 64 farms were tested for ECO by microbial culture. Sample prevalence of ECO in calves less than 8 weeks old was 1.4% and in calves 8 weeks or older was 4.8%. Calves were 3 times more likely to shed ECO after weaning than before weaning. Shedding of ECO was associated with grouping calves before weaning; feeding whole cottonseed was negatively associated with ECO shedding. The change in results between testing periods illustrated that an individual herd's status cannot be defined by a single testing of a small sample of cattle.

Age Factors↗
PubMed1995

Some risk factors associated with clinical lameness in dairy herds in Minnesota and Wisconsin.

An observational study of the relationships between clinical lameness and herd-level risk factors was made in 18 dairy herds in Minnesota and Wisconsin. Lameness in the lactating cows was assessed by two observers during herd visits made in the summer of 1989 and the spring of 1990, using a uniform scoring system. A questionnaire was used to obtain information about the general management, routine hoof care, nutrition, housing and flooring on the farms. Factors associated with the prevalence of clinical lameness in the summer included stall moisture, the size of the exercise area for the lactating cows and the amounts of dry concentrates and fresh forages fed to them. Factors associated with clinical lameness in the spring included the use of parlour milking facilities and the frequency with which the rations for the lactating cows were balanced.

Animal Feed↗
PubMed1995

Management factors related to Salmonella shedding by dairy heifers.

In a national survey of dairy operations with > or = 30 milking cows, fecal samples from 6861 preweaned dairy heifer calves on 1063 operations were tested for Salmonella. One hundred forty-five (2.1%) of the fecal samples from 79 (7.4%) of the farms tested positive for Salmonella. A multivariate logistic regression model revealed that medicated milk replacer and hay fed to dairy heifers from 24 h of age until weaning were associated with a reduced risk of Salmonella sheddings, as was calving in an individual animal area within a building.

Animal Feed↗