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Biomedical subjects

J Hopkins

Publications and source records attributed to J Hopkins.

At least 73 records · Page 4Linked to original sources
PubMed1996

Identification of the sheep homologue of the monocyte cell surface molecule--CD14.

An ovine monocyte/macrophage cell surface antigen was recognized by three mouse monoclonal antibodies (mAbs) VPM65, VPM66 and VPM67. These mAbs also reacted with bovine cells. The antibodies immunoprecipitated a single, glycosyl-phosphatidylinositol-linked polypeptide of M(r) 55,000 which, when deglycosylated, was reduced to M(r) 53,000. They reacted strongly with peripheral blood monocytes, alveolar macrophages and peripheral blood granulocytes, and weakly with afferent lymph dendritic cells. They also reacted with macrophages in many different tissues but were non-reactive with lymphocytes. Competitive flow cytometry shows that these three mAbs recognize the same or a closely related epitope of a single antigen. An antigen-specific capture ELISA using the anti-human CD14 mAb (TUK4) revealed that all four mAbs associate with the same antigen. These data demonstrate that the mAbs react with the ovine homologue of the lipopolysaccharide (LPS)-LPS binding protein receptor, CD14.

Animals↗
PubMed1996

Ruminant cluster CD14.

Following the analysis of flow cytometry data on ovine and bovine cells and immunoprecipitation, immunohistochemistry and competitive binding studies, a cluster of three monoclonal antibodies (mAbs) (VPM65, VPM66 and VPM67) appeared to be specific for the ruminant CD14 (Gupta, V.K., McConnell, I., Dalziel, R.G. and Hopkins, J., 1996. Identification of the sheep homologue of the monocyte cell surface molecule-CD14. Vet. Immunol. Immunopathol. in press; Hopkins, J. and Gupta, V.K., 1996. Characterization of 3rd Worshop monoclonal antibodies specific for sheep macrophages/monocytes. Vet. Immunol. Immunopathol., 52:329-339). According to flow cytometry results from human CD14-transfected COS-7 cells and from bovine peripheral blood mononuclear cells, another mAb (CC-G33), not submitted to the Workshop, recognised a bovine CD14 epitope which is conserved in the human CD14 (Sopp, P., Kwong, L.S. and Howard, C.J., 1996. Identification of bovine CD14. Vet. Immunol. Immunopathol., 52: 323-328).

Animals↗
PubMed1996

Discrimination of two subsets of CD1 molecules in the sheep.

This paper examines the expression of CD1 in the sheep utilising the monoclonal antibodies (mAbs) which were assigned to OvCD1 in the First and Second Workshops on Ruminant Leukocyte Differentiation Antigens along with those primarily clustered as Bov/OvCD1 in the Third Workshop. Detailed immunohistological studies of both lymphoid and non-lymphoid tissues and flow cytometry of isolated cell populations revealed two distinct patterns of CD1 expression in the sheep. The mAbs assigned to the sub-cluster BovCD1w1 (SBU-T6) and BovCD1w3 (IAH-CC43 and IAH-CC118) were much more widely distributed than those of the sub-cluster BovCD1w2. In addition to cortical thymocytes and dendritic cells (DC) the CD1w1 and w3 molecules are expressed by peripheral blood B lymphocytes, monocytes and many tissue macrophages.

Animals↗
PubMed1996

Identification of three myeloid-specific differentiation antigens in sheep.

The monoclonal antibodies submitted to the Third Workshop on Ruminant Leukocyte Antigens were analysed for their reactivity with sheep macrophage and monocyte populations. Initial analysis showed that, in addition to the anti-integrin mAbs, there were six mAbs that reacted with macrophages or monocytes but were unreactive on lymphocytes. Preliminary flow cytometry and immunohistology showed that there were three distinct groups of mAbs: Group 1 consisted of VPM65, VPM66 and VPM67; Group 2 consisted of just VPM64; Group 3 consisted of just VPM63. Further analysis demonstrated that Group 1 mAbs recognize the sheep homologue of CD14. Group 2 reacts with an M(r) 65,000-80,000 polypeptide possibly analogous to CD16 (Fc gamma RIII) and Group 3 reacts with an M(r) 40,000-42,000 doublet, probably identified as a minor isoform of sheep Fc gamma RII (CDw32). Another mAb (IL-A97) was similar in many respects to the Group 1 mAbs but there was a lack of data to confirm its specificity. All mAbs tested also reacted with cattle macrophages.

Amino Acid Sequence↗
PubMed1996

Eye manifestations of congenital toxoplasmosis.

PURPOSE: To determine the natural history of treated and untreated congenital toxoplasmosis and impact of this infection on vision. METHODS: In this prospective, longitudinal study, 76 newborns were treated with pyrimethamine and sulfadiazine for approximately one year, and 18 individuals not treated during their first year of life entered the study after age 1 year (historical patients). RESULTS: Chorioretinal scars were the most common eye finding in all patients and were most common in the periphery (58% of treated and 82% of historical patients). Macular scars were present in 54% of the treated patients; 41% were bilateral. Macular scars were present in 76% of the historical patients; 23% were bilateral. Visual acuity in the presence of macular lesions ranged from 20/20 to 20/400. Of the patients followed up from the newborn period and treated, 29% had bilateral visual impairment, with visual acuity for the best eye of less than 20/40. Causes for this visual impairment in eyes with quiescent lesions included macular scars, dragging of the macula secondary to a peripheral lesion, retinal detachment, optic atrophy, cataract, amblyopia, and phthisis. There were recurrences in both treated (13%, 7/54) and previously untreated historical patients (44%, 8/18). The total, median, and range of years of follow-up during which recurrences were observed were, for treated patients, 189 years (total), five years (median), and three to ten years (range) and, for historical, untreated patients, 160 years (total), 11 years (median), and three to 24 years (range). New lesions occurred in previously normal retinas and also contiguous to older scars. Active lesions appeared to become quiescent within ten to 14 days after beginning pyrimethamine and sulfadiazine therapy. CONCLUSION: Many children with congenital toxoplasmosis have substantial retinal damage at birth and consequent loss of vision. Nonetheless, vision may be remarkably good in the presence of large macular scars. Active lesions become quiescent with treatment.

Adolescent↗
PubMed1996

Trypanosoma congolense infection in sheep: cellular phenotypes in lymph and lymph nodes associated with skin reactions.

Intradermal inoculation of sheep with culture-derived metacyclic forms of Trypanosoma congolense resulted in the development of localized skin reactions (chancres) and enlargement of the draining lymph nodes 7 days after infection. Changes in the expression of surface antigens of lymphocytes in lymph leaving the affected skin reactions and in the associated lymph nodes were monitored by cannulating the afferent and efferent lymphatic ducts. Trypanosomes appeared in afferent and efferent lymph 3 to 5 days after infection and persisted even as the chancres regressed. The cellular output in both afferent and efferent lymph increased markedly after the onset of parasitosis. Sequential analysis of the phenotypes of lymphocytes by immunofluorescent staining and flow cytometry revealed that in afferent lymph draining the chancre there was an early response which was due to an increase in T cells, particularly CD4+ and CD8+ cells; however, as the chancres-regressed there was an increase in lymphoblasts and surface immunoglobulin-bearing cells. In contrast, in the efferent lymph, the increase in lymphocytes was due predominantly to a higher number of cells bearing surface immunoglobulins.

Animals↗
PubMed1996

Fc gamma receptor expression on sheep afferent lymph dendritic cells and rapid modulation of cell surface phenotype following Fc gamma receptor engagement in vitro and in vivo.

Afferent lymph dendritic cells were analysed for the presence of Fc gamma receptors by Western blotting and for modulation of surface markers following Fc gamma receptor engagement in vitro and in vivo. The results showed that unstimulated dendritic cells expressed Fc gamma RII constitutively. When dendritic cells were incubated in vitro with antigen/antibody complexes in antibody excess, a marked reduction in surface staining was observed for MHC class II, CD1, CD44, and VLA-4 after 8 h in culture. These changes did not occur with antigen or antibody alone. DC expression of LFA-1 and LFA-3 were slightly reduced after 8 h in culture with Ova alone, but this was enhanced slightly when the cells were cultured with immune complexes. Even more marked reductions in surface staining for MHC class II, CD1, CD44 and VLA-4 were observed on dendritic cells 4-8 h following secondary antigen challenge in vivo. LFA-1 and LFA-3 expression was reduced only slightly. The level of expression of MHC class II, CD1, LFA-1 and LFA-3 was substantially increased over resting values 24 h after Fc gamma R occupancy. The intensity of staining at this time was also significantly elevated for CD44, LFA-1, LFA-3 and VLA-4. These results show that engagement of Fc gamma receptors cause a substantial modulation of the dendritic cell surface phenotype after immune complex uptake. The phenomenon may function to maximize subsequent presentation of the challenge antigen to T cells.

Animals↗
PubMed1996

Congenital toxoplasmosis transmitted from an immunologically competent mother infected before conception.

Congenital transmission of Toxoplasma gondii from a mother who was apparently immunologically competent and who had toxoplasmic lymphadenitis 2 months before conception is described. Since no T. gondii-specific serological data were available for this mother from the time her lymph node biopsy specimen was obtained, the specimen was studied by polymerase chain reaction (PCR) to determine whether the T. gondii B1 gene was present. The predictive diagnostic value of histologic findings previously considered to be classic signs of T. gondii lymphadenitis also was studied. This was done by correlation of serological tests diagnostic of acute acquired T. gondii infection and presence of characteristic findings in biopsy specimens from persons without known immunocompromise. Both PCR and review of the characteristic features of her lymph node biopsy specimen confirmed the diagnosis of preconceptual infection in the mother. We also discuss two other cases in which apparently immunologically competent mothers with preconceptually acquired infection transmitted this parasite to their fetuses.

Animals↗
PubMed1996

Resolution of intracranial calcifications in infants with treated congenital toxoplasmosis.

PURPOSE: To determine the natural history of intracranial calcifications in infants with treated congenital toxoplasmosis. MATERIALS AND METHODS: Between January 1982 and March 1994, cranial computed tomography was performed in 56 infants with treated congenital toxoplasmosis when they were newborns and approximately 1 year old. Locations and sizes of intracranial calcifications were noted. RESULTS: Forty newborns had intracranial calcifications. By 1 year of age, calcifications diminished or resolved in 30 (75%) and remained stable in 10 (25%) of these treated infants. Ten (33%) of the 30 infants whose calcifications diminished versus seven (70%) of the 10 infants with stable calcifications received less intensive antimicrobial treatment than the other treated infants. In contrast, a small number of infants who were untreated or treated 1 month or less had intracranial calcifications that increased or remained stable during their 1st year of life. CONCLUSION: Diminution or resolution of intracranial calcifications was an unexpected and remarkable finding in infants with treated, congenital toxoplasmosis, consonant with their improved neurologic functioning.

Anti-Infective Agents↗
PubMed1996

Expression and function of thyroid hormone receptor variants in normal and chronically diseased human liver.

As the liver represents a major target organ for thyroid hormone action, we compared the expression of thyroid hormone receptor (TR) alpha and beta variants in normal human liver and liver affected by primary biliary cirrhosis, sclerosing cholangitis, cryptogenic cirrhosis, and alcoholic cirrhosis (n = 6 in each group). Western blot analysis using specific polyclonal antibodies to alpha 1 or beta 1 TRs or to the related non-T3-binding c-erbA alpha 2 variant revealed abundant expression of TRs in normal and diseased liver, with no difference in size or abundance of TR proteins. Immunocytochemistry likewise revealed abundant nuclear expression of TR proteins in normal and diseased liver, with similar patterns and intensity of staining. Despite abundant TR protein expression, Northern blot hybridization of polyadenylated ribonucleic acid (RNA; 10 micrograms) to TR complementary DNAs revealed only a weak signal for c-erbA alpha 2 messenger RNA (mRNA). Comparison of the level of expression of the thyroid hormone-regulated mRNAs encoding T4-binding globulin, sex hormone-binding globulin, cortisol-binding globulin, and transthyretin in normal and diseased tissue revealed no significant difference, suggesting that hepatocellular expression of these mRNAs is maintained in chronic liver disease despite a marked reduction in circulating T3 concentrations.

Animals↗
PubMed1996

The sheep CD1 gene family contains at least four CD1B homologues.

We identified four cDNA sequences encoding sheep homologues of the CD1 molecule. The sheep sequences were selected from lambdagt11 thymocyte cDNA libraries by hybridization with a human CD1C probe and a homologous sheep probe. The SCD1B-42 and SCD1A25 sequences encode complete CD1 molecules. The third sequence, SCD1B-52, which is closely related to SCD1B-42 and may be an allele, has the sequence encoding the alpha3 region precisely deleted. The fourth sequence, SCD1T10, is truncated at the 5' end. All four sequences are related to the human CD1B and domestic rabbit CD1B-like sequences at both nucleotide and amino acid level. Comparison of the derived CD1 amino acid sequences with the sequence of major histocompatibility complex class I molecules showed that the sheep CD1 molecules, like human CD1 molecules, lack most of the conserved class I residues known to be involved in interaction with beta2-microglobulin and the CD8 molecule. They do not contain the peptide docking residues involved in anchoring peptides in the peptide binding groove of class I molecules. Southern hybridization of sheep DNA with a sheep CD1 exon 4/alpha3 probe showed that the sheep genome encodes at least seven CD1 genes. The implications of these analyses for CD1 function are discussed.

Amino Acid Sequence↗
PubMed1996

Ventral hernia repair with simultaneous panniculectomy.

The repair of a ventral hernia in an obese patient presents an interesting clinical challenge. We retrospectively reviewed the charts of 55 patients who, over a 12-year period from 1983 to 1995, concomitantly underwent both ventral herniorrhaphy and panniculectomy or abdominoplasty. In six of 55 patients, the hernia was recurrent. Forty-six patients had primary abdominal wall hernias or diastasis recti. Nineteen of 55 patients had weight greater than 200 lbs. This last subset of patients had a significantly higher incidence of complications, such as seroma, cellulitis, and persistent wound drainage. In our 55 patients, we experienced only two hernia recurrences (3.6%) during an average patient follow-up of 53 weeks. From this experience, we believe that simultaneous ventral hernia repair and panniculectomy is a safe and efficacious approach to these two problems so commonly found in the obese patient. Patients with a preoperative weight greater than 200 lbs can be expected to have a greater risk of wound complications. In all cases, the wounds eventually healed with no long-term sequelae.

Adipose Tissue↗
PubMed1995

Analysis of the expression and secretion of isotypes of sheep B cell immunoglobulins with a panel of isotype-specific monoclonal antibodies.

Monoclonal antibodies to sheep light chain, IgM and IgG were produced and used to assess total immunoglobulin (Ig) synthesis by sheep B cells in culture and antibodies to specific antigens. By using these antibodies in a dual fluorescence-activated cell sorting analysis of sheep efferent lymph B lymphocytes the percentage change in surface Ig isotype of B lymphoblasts from IgM to IgG after the antigenic stimulation of the local lymph node was measured. An extension of this analysis to paired blood and afferent or efferent lymph B cells made it possible to investigate the recirculation characteristics of B cells expressing different Ig isotypes.

Animals↗
PubMed1995

Variable expression of major histocompatibility complex class II in the domestic cat.

This paper describes the characterisation of six independently produced monoclonal antibodies (mAbs) specific for non-polymorphic determinants of feline major histocompatibility complex (MHC) class II. One mAb is an anti-sheep class II which cross-reacts with the cat and five have been produced in response to immunisation with purified feline immunodeficiency virus. Despite their independent source all the mAbs have identical reactivities, immunoprecipitating two complex groups of polypeptides of M(r) 33 to 36.000 (MHC class II alpha chains) and M(r) 28 to 31,000 (MHC class II beta chains). Immunoblot analysis showed them to be beta chain-specific. One and two-dimensional electrophoresis revealed the complexity of feline class II mass and charge and implied the expression of multiple class II loci in the cat. Furthermore, it was demonstrated that distinct cell populations expressed a distinct range of class II variants. This suggesting either the differential expression or the distinct post-translational modification of lymphocytes from different sites. The mAbs have also been used for the detailed examination of the cellular distribution and tissue localisation of MHC class II in the cat.

Animals↗
PubMed1995

Identification of CD45 (leucocyte common antigen) in the domestic cat.

Feline CD45 (leucocyte common antigen, LCA) was characterised by using the mouse monoclonal antibody, WC45a. Its specificity was established on the basis of its reactivity with different lymphoid tissues, as judged by flow cytometry and immunohistochemistry, and of the molecular weight of its antigen in different tissues. It reacted with all the leucocyte populations tested including T and B lymphocytes, granulocytes and monocytes. By immunohistology it reacted only with leucocytes and not with endothelia, epithelia or connective tissue. It precipitated cell surface polypeptides, of M(r) 180,000 to 220,000 from lymph node cells, and therefore apparently recognised an epitope represented on most of the isoforms of the CD45 family.

Animals↗
PubMed1995

A study on lymphocyte activation in maedi-visna virus induced pneumonia.

The stage of activation of bronchoalveolar lavage fluid (BALF) lymphocytes and peripheral blood lymphocytes (PBL) from maedi-visna virus (MVV) infected (n = 7) and control (n = 7) sheep was investigated by assessing four parameters of lymphocyte activation; lymphocyte size and complexity, loss of CD5+ T cells, expression of cell surface interleukin-2 receptor (IL-2R) and expression of DR and DQ MHC Class II molecules. BALF lymphocytes from MVV-infected animals had a significant loss of CD5+ lymphocytes (P < 0.05) and upregulation of DR and DQ MHC Class II molecules compared with controls, consistent with BALF lymphocyte activation. No changes in cell size and complexity or expression of IL-2R were observed. No evidence of PBL activation was detected. These findings suggest an impaired BALF lymphocyte activation during MVV infection.

Animals↗