Biomedical subjects

R M Jacobs

Publications and source records attributed to R M Jacobs.

At least 37 records · Page 2Linked to original sources

PubMed1996

Histopathological changes in the lymphoid tissues of sheep exposed to the bovine immunodeficiency-like virus.

Six yearling sheep were inoculated intraperitoneally with peripheral blood from two sheep infected with the bovine immunodeficiency-like virus (BIV) strain R29. An additional five sheep served as sham-inoculated controls. Of the six sheep given BIV, five seroconverted, one of them remaining seropositive for the duration of the study. The polymerase chain reaction demonstrated BIV provirus in three of the five serologically positive animals. At necropsy, 1 year after inoculation, histological changes were found only in the lymphoid tissues. In sheep exposed to BIV, mild though significant increases were seen in the (1) number of splenic periarteriolar lymphoid sheaths, (2) number of secondary follicles in hilar and prescapular or popliteal lymph nodes, and (3) medullary sinus cellularity in prescapular and popliteal lymph nodes.

Animals↗

PubMed1995

Pathology of canine bladder and urethral cancer and correlation with tumour progression and survival.

Biopsy and necropsy specimens, comprising 107 primary carcinomas and three mesenchymal tumours, were reviewed from 110 dogs with cancer of the bladder, urethra, or both. Histological classifications developed for the assessment of human bladder cancer were found to be readily applicable to the dog. These classifications are based on histological features, including the pattern of growth, the cell type, the grade of transitional tumour and the depth of invasion of the bladder wall. Features associated with localized disease in canine transitional cell carcinoma included papillary architecture, "in-situ" tumour, low tumour grade and a strong peritumoral lymphoid cell reaction. Features of tumours with metastasis included infiltrating and non-papillary architecture, increasing tumour grade, depth of invasion, vascular invasion and presence of peritumoral fibrosing reaction. Wide variability was found within single tissue samples, indicating that multiple sample sites are necessary for the adequate characterization of a given lesion. Statistically significant correlations were found between: tumour grade and depth of invasion (P < 0.0001); tumour grade and presence of metastases (P < 0.029); and peritumoral desmoplasia and metastases (P < 0.029). It was concluded that canine bladder cancer could be classified for the purpose of clinical management with a modified World Health Organization system as developed for human tumours.

Animals↗

PubMed1995

Comparison of direct and indirect blood pressure measurements in anesthetized dogs.

The precision and accuracy of an indirect oscillometric blood pressure measurement technique (Dinamap 8100) was assessed in 11 anesthetized Beagle dogs weighing 8 to 11.5 kg. Direct blood pressure measurements were made by catheterization of the lingual artery, and simultaneous indirect measurements were determined by placing a cuff over the median artery (midradial area). Blood pressure measurements at 2 different planes of anesthesia (light and deep) were recorded in triplicate. At a light plane of anesthesia, the Dinamap 8100 underestimated diastolic and mean arterial pressure, and at a deep anesthetic plane overestimated systolic pressure. The indirect technique had good repeatability of systolic pressures. Regression analysis for the 2 techniques showed excellent correlation (r = 0.93). The results indicate that the indirect oscillometric blood pressure measurement technique provides a good estimate of systolic, diastolic, and mean arterial pressure in dogs weighing 8-11.5 kg.

Anesthesia↗

PubMed1995

A serological survey of bovine syncytial virus in Ontario: associations with bovine leukemia and immunodeficiency-like viruses, production records, and management practices.

Of the 920 cows tested, 56.7% showed antiretroviral serological reactivity. Prevalence rates (95% confidence interval) of antiretroviral antibodies among individual dairy cows in Ontario were: BIV 5.5% (4.0-7.0), BLV 25.7% (22.9-28.6), and BSV 39.6% (36.4-42.8). The following percentages of cows showed serological reactivity against the specified retroviruses: BIV 2.3%, BLV 14.0%, BSV 27.5%, BIV and BSV 1.3%, BIV and BLV 0.9%, BLV and BSV 9.9%, BIV and BLV and BSV 0.9%. These rates of sero-positivity are similar to those found in other countries. Serological test results were not adjusted for sensitivity and specificity. The prevalence rates of antibodies to the three retroviruses (BIV, BLV, and BSV) were significantly different, but no associations were observed between specific retroviral serological test results among individual cows. The prevalence rates of BIV and BSV seropositivity were constant across Ontario, whereas, there was a significant trend for the prevalence rate of BLV seropositivity to decrease going from southwestern to eastern Ontario; cows in eastern Ontario had approximately half the prevalence rate of those in southwestern Ontario. Cows that were seropositive for BSV were significantly older than BSV seronegative cows. There was no association between culling rate and BSV serology. Significant negative associations were found with winter or summer housing of calves separate from adults and summer outdoor exercise for dry cows. The use of calf hutches in the summer had a significant positive association with BSV seropositivity. Regression analyses were done to assess the association of retroviral (BIV, BLV, and BSV) seropositivity on calving interval, milk somatic cell count, and milk production. Serological test results for BIV, BLV, and BSV were entered into all models and all models were adjusted for intra-cluster (intraherd) correlation. Herd size and age were found to be important confounding variables. BIV seropositivity was not associated with any changes in production using this approach, however when considered in isolation BIV seropositivity remained associated with decreased milk production. BLV seropositivity was significantly associated with longer calving intervals and higher somatic cell counts in older cows. As well, in older cows, BSV seropositivity was significantly associated with higher milk production.

Age Factors↗

PubMed1994

Gene transfer into hematopoietic stem cells: long-term maintenance of in vitro activated progenitors without marrow ablation.

Adoptive transfer of genetically modified somatic cells will play an increasingly important role in the management of a wide spectrum of human diseases. Among the most appealing somatic cells as potential gene transfer vehicles are hematopoietic cells, because of their wide distribution and their well-characterized capacities for proliferation, differentiation, and self-renewal. Genes can be readily transferred into short-lived and lineage-restricted hematopoietic cells, but there remains a need to develop reliable methods for gene transfer into hematopoietic stem cells in large animals. In this work, we used a gene transfer approach in which hematopoietic cells in long-term marrow cultures were exposed to the replication-defective retrovirus N2, bearing the reporter gene neo, on multiple occasions during 21 days of culture. Genetically marked cultured autologous cells were infused into 18 canine recipients in the absence of marrow-ablative conditioning. neo was detected by Southern blotting and/or the polymerase chain reaction in the marrow, blood, marrow-derived granulocyte/macrophage and erythroid progenitors, and cultured T cells in dogs after infusion. In most dogs, the proportion of long-term marrow culture cells contributing to hematopoiesis rose during the first 3 months after infusion and peaked within the first 6. The maximal levels attained were between 10% and 30% G418-resistant (neo-positive) granulocyte/macrophage progenitors. At 12 months, five dogs maintained greater than 10% G418-resistant progenitors, and for two of them this level exceeded 20%. Two dogs had greater than 5% G418-resistant hematopoietic progenitors at 24 months after infusion. Our data suggest that very primitive hematopoietic progenitors are maintained in long-term marrow cultures, where they can be triggered into entering the cell cycle. In vivo, these activated cells likely continue normal programs of proliferation, differentiation, and self-renewal. Their progeny can be maintained at clinically relevant levels for up to 2 years without the requirement that endogenous hematopoiesis be suppressed through chemo- or radiotherapy prior to adoptive transfer. Long-term marrow culture cells may thus be ideal targets for gene therapy involving adoptive transfer of transduced hematopoietic cells.

Animals↗

PubMed1994

Haematological and lymphocyte subset analyses in sheep inoculated with bovine immunodeficiency-like virus.

Bovine immunodeficiency-like virus (BIV) was passaged in vivo by intraperitoneal transfusion of ovine whole blood. Prior to transfusion, the recipient sheep were given sodium thioglycolate intraperitoneally to induce mild non-suppurative inflammation. The anti-BIV antibody response, haematology, and peripheral blood lymphocyte subsets (B, gamma delta, CD2+, CD4+ and CD8+) of recipient sheep were assessed for one year following transfusion. Passaging was successful since serum anti-BIV antibody responses were detected in 5 of the 6 recipient sheep; 1 of the 5 remained seropositive throughout the study. Lentivirus was not isolated from the recipient sheep, but provirus was detected by the polymerase chain reaction in DNA from peripheral blood leukocytes in 3 of the 5 sheep that seroconverted. In the BIV-inoculated sheep, neutrophils and eosinophils were significantly increased (p < or = 0.05) at 3 months and between 6 and 8 months postinoculation, respectively. B, CD2+ and CD4+ cells and the CD4+/CD8+ ratios were significantly increased (p < or = 0.05) 2 months postinoculation. Mild, transient haematological changes occurred in BIV-exposed sheep, but illness was not detected in the year.

Animals↗

PubMed1994

Nonrandom chromosomal abnormalities in bovine lymphoma.

Despite detailed knowledge of the genetic map of the bovine leukemia virus (BLV), the mechanism whereby BLV infection results in transformation and B-lineage restriction of tumors is poorly understood. The aim of this study was to gain new insight into pathogenetic mechanisms of BLV-induced tumorigenesis by determining the karyotypes of BLV-associated lymphomas in cattle. Metaphases in cells from lymphoid tumors from 20 mature dairy cows were banded and analyzed after short-term, unstimulated culture. Nineteen out of twenty cases exhibited clonal abnormalities, 17 cases were hyperdiploid, and 16 cases had extremely complex chromosomal changes. Recurrent chromosomal anomalies were identified and there was clear evidence for the evolution of increasing chromosomal instability in 12 cases. The most common abnormalities were the acquisition of additional small chromosomes (23-29); trisomy of chromosomes 5 and 7, and Robertsonian translocations and isochromosome rearrangements involving chromosomes 10, 12, 23, and 26. Monosomy X, trisomy X, and translocations involving the X chromosome were also detected. Chromosomes 2, 3, 4, 6, 8, 9, 11, 13, 14, 19, and 21 were infrequently involved in either structural or numerical changes. Structural rearrangements of chromosomes 10, 12, 23, and 26 may reflect primary abnormalities occurring relatively early in transformation, whereas trisomy 5 may be an extremely common secondary abnormality. While comparison of these findings with the current bovine gene map raises intriguing possibilities for pathogenetic mechanisms, further studies are needed before hypothetical mechanisms linking chromosomal abnormalities with BLV-induced transformation can be made.

Animals↗

PubMed1994

Cell-mediated and humoral immunity in sheep exposed to bovine immunodeficiency-like virus.

Six sheep were transfused intraperitoneally with whole blood from two sheep chronically infected with the bovine immunodeficiency-like virus (BIV). Five sheep were transfused intraperitoneally (i.p.) with normal ovine whole blood and served as controls. Five of six BIV-inoculated sheep seroconverted; four were transiently seropositive while one remained seropositive for the duration of the experiment. Tests for nonspecific lymphocyte reactivity to mitogens were performed monthly for one year. At approximately 10 months postinoculation, all sheep were immunized with chicken ovalbumin, canine red blood cells, and tuberculin. There were no significant associations between BIV exposure and deficits in antibody production to chicken ovalbumin and canine red blood cells; nonspecific lymphoproliferative responses to concanavalin-A, lipopolysaccharide, and pokeweed mitogen; specific lymphoproliferative responses to ovalbumin and tuberculin purified protein derivative; or cutaneous delayed type hypersensitivity to tuberculin purified protein derivative. Exposure to BIV did not alter the humoral or cell mediated immune responses of sheep in the first year of exposure.

Animals↗

PubMed1994

Flow cytometric analysis of ovine peripheral blood lymphocytes.

Leukocyte suspensions were prepared from the peripheral blood of 12 sheep three times at two month intervals beginning at 12 months of age. Monoclonal antibodies and flow cytometric analysis were used to characterize the cells. There were no significant differences over time therefore the data from the three time intervals were pooled. The mean percentages and ranges (minimum to maximum) of the major lymphocyte subtypes were: B-cells (29.6%, 11-50), gamma delta T-cells (36.6%, 22-68), CD4+ T-cells (14.1%, 8-22) and CD8+ T-cells (12.0%, 4-22). Lymphocyte subtype percentages appeared less variable within than between individuals. Two populations of B-cells were noted; one population had more cytoplasm and light scatter characteristics similar to monocytes while a second population of B-cells was more typical of small lymphocytes. The nature of the large B-cells requires further study.

Animals↗

PubMed1994

A serological survey for bovine immunodeficiency-like virus in Ontario dairy cattle and associations between test results, production records and management practices.

A chemiluminescence Western blot analysis (WBA) for detecting antibovine immunodeficiency-like virus (BIV) antibodies, had good repeatability. The test was subsequently applied to a bank of serum samples from 928 adult cows from 265 herds in Ontario; the number of cows sampled within each herd ranged from 1 to 13. The overall prevalence of anti-BIV antibodies among cows was 5.5% with a 95% confidence interval of 4.2% to 7.2%. In contrast, 18.1% of herds had at least one reactor among cows tested, resulting in a herd-prevalence confidence interval of 13.8% to 23.4%. These estimates of prevalence were in the same range as previous reports from the US and Europe. Bovine immunodeficiency-like virus may have a worldwide distribution. Unfortunately, BIV test sensitivity and specificity are difficult to estimate because virus isolation is inefficient. Therefore, the apparent prevalences could not be adjusted for test sensitivity and specificity, to estimate the true prevalence of infection. The serum samples had previously been tested for antibodies to bovine leukemia virus (BLV). There were no significant associations between BIV and BLV test results. Least squares regression was used to investigate potential associations between BIV test results and selected production indices.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Husbandry↗

PubMed1993

Detection of bovine immunodeficiency-like virus by the polymerase chain reaction.

This report describes a test for the bovine lentivirus, bovine immunodeficiency-like virus, in which polymerase chain reaction (PCR) technology is employed. Two pairs of oligonucleotide primers directed to sequences within the coding regions of the gag and pol genes generated the expected PCR products from molecular BIV clones and from DNA of BIV-infected cell cultures but not from DNA of uninfected cultures. Data indicating the specificity and sensitivity of these PCRs for BIV detection and the potential utility of this technology for diagnostic applications are presented.

Animals↗

PubMed1993

Detection of bovine leukemia virus RNA in serum using the polymerase chain reaction.

A method was developed for detecting bovine leukemia virus (BLV) RNA in serum samples using a pair of primers from the BLV polymerase gene in the polymerase chain reaction (PCR). The PCR was able to detect 3800-7600 molecules of BLV RNA. At this level of sensitivity eleven pools of adult and one fetal bovine serum appeared free from BLV contamination.

Animals↗

PubMed1993

Serological evidence of bovine immunodeficiency-like virus infection in a sheep.

A six month-old sheep was entered into a control group in an experiment designed to study the effects of exposure to the bovine immunodeficiency-like virus (BIV). Anti-BIV antibodies were detected in the serum of this sheep prior to the start of the study; these antibodies persisted for 12 months at which time the animal was destroyed. The sheep was normal clinically and was grossly normal at postmortem examination. Blood from this sheep was inoculated into a recipient sheep which subsequently showed a transient anti-BIV antibody response beginning two months postinoculation. Sheep have been previously shown to produce anti-BIV antibodies after experimental inoculation with infected cell culture material or infected bovine blood and BIV infection was found in a sheep pastured with BIV-infected cattle. In the present case there was no contact with cattle; the source of the infection was not identified.

Animals↗

PubMed1993

Effects of plasma and serum on the in vitro expression of bovine leukemia virus.

BACKGROUND: Bovine leukemia virus (BLV) is difficult to detect in freshly isolated peripheral blood mononuclear cells (PBMCs) from infected cattle. The lack of viral expression has been attributed to a plasma blocking factor capable of inhibiting the in vitro expression of the BLV p24 antigen. EXPERIMENTAL DESIGN: The purpose of this study was to investigate the effects of plasma and serum on the in vitro synthesis of the p24 antigen within short-term cultures of PBMCs from BLV-seropositive cows. BLV p24 antigen was detected in the cell lysate using an antigen capture enzyme-linked immunosorbent assay. RESULTS: Antigen synthesis was suppressed in PBMCs cultured in plasma from both seropositive and seronegative cows. Serum from infected cows suppressed p24 expression, but to a lesser extent than any of the plasmas. Addition of phytohemagglutinin-P to the cultures resulted in the detection of more p24 in PBMCs cultured in serum, but had no effect on p24 expression within cells cultured in plasma. The reduction in p24 was not related to lower cell viability, nor was it influenced by the effects of the anticoagulant citrate-phosphate dextrose on calcium-dependent lymphocyte activation. No significant difference was observed in the potency of the p24 inhibition between cells grown in autologous and homologous serum, or between cells grown in autologous and homologous plasma from seropositive cows. CONCLUSIONS: Blocking activity is present in the plasma of seronegative cows, and in the plasma and serum of BLV-seropositive cows. This activity may be important in regulating viral latency and provirus expression in vivo.

Animals↗

PubMed1992

Classification of 1,198 cases of bovine lymphoma using the National Cancer Institute Working Formulation for human non-Hodgkin's lymphomas.

A retrospective histologic study was made of 1,198 cases of bovine lymphoma using the National Cancer Institute Working Formulation for human non-Hodgkin's lymphoma. This classification scheme was found to be readily applicable to bovine lymphoma. Most of the cell types described in the National Cancer Institute Working Formulation occurred in this series of bovine lymphomas, but the distribution of cell types varied markedly compared to that of human beings. Eighty-nine percent (1,067/1,198) of bovine lymphomas were high-grade tumors. The diffuse large cell type and its cleaved variant comprised 65.9% of all bovine lymphomas. Similar to the dog, but in marked contrast to human beings where at least 34% of non-Hodgkin's lymphomas were follicular, follicular tumors were found to be extremely rare in cattle (0.3% or 4/1,198). The prevalence of cell types varied significantly between the enzootic and sporadic lymphomas. The cleaved variant of the diffuse large cell type constituted 38% (406/1,072) of enzootic lymphomas versus 14% (18/126) of sporadic lymphomas. The mitotic index (100 x oil immersion field, 175 microns in diameter) of enzootic lymphomas (3.72 +/- 0.06, mean +/- standard error) was significantly greater than the mitotic index of sporadic lymphomas (2.82 +/- 0.17). We concluded that the cleaved variant of the diffuse large cell type with high mitotic index is characteristic of enzootic lymphoma. This characteristic high-grade cell type may be a consequence of the viral etiology of the enzootic form of bovine lymphoma.

Age Factors↗

PubMed1992

Evidence for bovine leukemia virus infection of peripheral blood monocytes and limited antigen expression in bovine lymphoid tissue.

Bovine leukemia virus (BLV) infection of cattle is a common but inapparent retrovirus infection from which less than 5% of infected cattle manifest clinically with lymphoma. During the course of life-long infection, cattle maintain a high anti-BLV titer during an apparent latent infection of B cells from which proviral DNA but not transcripts can be detected. To investigate if BLV infection is truly latent and restricted only to B lymphocytes, peripheral blood leukocytes were purified from cattle with naturally acquired BLV infection with various stages of subclinical and clinical disease. These cells were purified into populations of polymorphonuclear cells, monocytes and subsequently B cells and T cells by fluorescent-activated cell sorting. Southern blot analysis revealed the presence of provirus in monocytes and B cells but not T cells. Secondly, the ability of provirus containing cell types to express BLV antigens was then confirmed by mitogen stimulation in vitro. Subsequently, the pattern of expression of BLV antigens was studied in situ in tissue sections to determine the location of BLV antigen expressing cells in vivo. Antigen expressing cells were infrequent and solitary in intrafollicular and marginal zone cells of architecturally normal lymph nodes of chronic, BLV-infected cattle. These results demonstrate that BLV persists in cells of the monocyte/macrophage lineage in addition to B lymphocytes and that expression of BLV antigens in cattle doses occur but rarely in lymph nodes of BLV infected cattle. The high frequency of provirus containing cells and infrequent expression of BLV antigen in vivo suggests that BLV expression is not truly latent but highly regulated, possibly triggered by rare events in host lymphoid tissue.

Animals↗

PubMed1992

Proviral detection and serology in bovine leukemia virus-exposed normal cattle and cattle with lymphoma.

Twenty-seven cattle with lymphoma and 46 cows from a known bovine leukemia virus (BLV)-infected herd were tested for anti-BLV antibody by the agar gel immunodiffusion (AGID) test and an enzyme-linked immunosorbent assay (ELISA). The polymerase chain reaction (PCR) and Southern hybridization were used to detect BLV provirus in the tumor DNA of the 27 cattle with lymphoma. The PCR was used to detect BLV provirus in the peripheral blood mononuclear cell DNA of the 46 normal known-exposed cattle. Two presumed false negative AGID test results compared to ELISA were found. Of ten cattle three years of age or less with "sporadic" forms of lymphoma, four had BLV provirus in tumor DNA, detectable by PCR. In two of these four, BLV provirus was clonally integrated based on digestion of tumor DNA with restriction enzymes followed by Southern hybridization. The BLV provirus was not detected by PCR in 5 of 17 cattle with "enzootic" lymphoma and two of these five were seronegative. Among normal BLV-exposed cows, 6.5% (3 of 46) were serologically positive and PCR negative; serologically negative and PCR positive cows occurred with the same frequency. Serological and PCR test results, when considered in all cattle (n = 73), had a concordance rate of 83.6%. Discordant test results occurred with approximately equal frequency between serologically positive and PCR negative (7 of 73, 9.6%) and serologically negative and PCR positive (5 of 73, 6.8%) groups. These data suggest that the role of BLV in some "sporadic" bovine lymphomas, previously unassociated with BLV, should be reexamined. The BLV provirus was not demonstrable in the tumor DNA from five adult cattle with lymphoma, suggesting that BLV may not be the etiological agent in all adult bovine lymphomas. The findings of persistently seronegative PCR positive and seropositive PCR negative cattle indicate that further work is needed to more fully understand the host-virus interaction. Present serological screening methods may not have sufficient sensitivity for determining BLV status in some circumstances.

Animals↗

PubMed1992

Detection of multiple retroviral infections in cattle and cross-reactivity of bovine immunodeficiency-like virus and human immunodeficiency virus type 1 proteins using bovine and human sera in a western blot assay.

Bovine antibovine immunodeficiency-like virus (BIV) antibodies were detected by Western blot analysis (WBA) using a chemiluminescence protocol. Bovine sera with anti-BIV activity, obtained from cows in two dairy herds, had antibodies directed against a variety of BIV-specific antigens indicating chronic infections. These sera were also tested for serological reactivity against bovine leukemia virus (BLV) and bovine syncytial virus (BSV). Cows most commonly had anti-BSV antibodies (12 of 39). Evidence for infection with BSV and BIV or BSV and BLV occurred with almost equal frequency (5 of 39 and 4 of 39, respectively) while only one instance of BIV and BLV coseropositivity was detected. The high prevalence of BSV seropositivity is consistent with a relatively infectious virus, which, as is known, may be transferred congenitally. Similar rates of coseropositivity of BIV or BLV with BSV in this population suggest that BIV is no more infectious than BLV and probably requires prolonged close contact for transmission. Seven of nine cows with anti-BIV antibodies detected primarily human immunodeficiency virus type 1 (HIV-1) p51 and p63 antigens by WBA using an alkaline phosphatase detection system, suggesting that HIV-1 proteins have potential usefulness in screening cattle for BIV seropositivity. Six human sera that showed strong reactivity against multiple HIV-1 proteins and the serum from one of three patients considered to be an "indeterminate" HIV-1 reactor, cross-reacted primarily with BIV p26. This is the first report of human sera with antibody to BIV-specific proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗