PubMed Health⌕ Search

Biomedical subjects

J Hopkins

Publications and source records attributed to J Hopkins.

At least 19 recordsLinked to original sources
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

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↗
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↗
PubMed1995

Biochemical and phenotypic characterization of the ovine beta 2 (leucocyte) integrins.

This paper is concerned with the relationship of the three distinct members of the ovine beta 2-integrin family of leucocyte adhesion molecules that play an important role in cell-cell and cell-matrix interactions. A panel of monoclonal antibodies (mAbs) specific for sheep and cattle macrophages was characterized by flow cytometry, immunohistology, and immunoprecipitation for reactivity to the beta 2 integrins. Immunoprecipitation analysis of sheep antigens showed that these monoclonal antibodies could be divided into four distinct groups. All precipitated an M(r) 95,000 beta chain but they differed in the size or number (or both) of the alpha chains recognized. Group 1 precipitated alpha chains of M(r) 180,000; group 2 had M(r) 170,000 alpha chains; the group 3 alpha chain was of M(r) 150,000 and group 4 mAbs precipitated alpha chains of all three sizes. The relationship between these antibodies was demonstrated by sequential immunoprecipitation, which showed that the reactivities of antibodies in groups 1, 2 and 3 were mutually exclusive but that group 4 antibodies shared a common specificity with the other three groups. By analogy with the human and murine beta 2 integrin families, group 1 antibodies seemed to be specific for CD11a (LFA-1); group 2 were CD11b (CR3 or Mac1); group 3 were CD11c (CR4 or p150/95) and group 4 were CD18. In addition to different molecular weights, these antibodies had different cellular and tissue distributions. CD11a and CD18 were distributed identically. The antigens recognized by both were present on all the leucocyte populations. The mAbs recognizing CD11b reacted with a sub-population of peripheral blood B lymphocytes and all myeloid cells (alveolar macrophages, peripheral blood monocytes and granulocytes) except afferent lymph dendritic cells (ADC). Anti-CD11c (p 150/95 or CR4) antibodies reacted strongly with macrophages and ADC but were weakly reactive on monocytes and negative on neutrophils. CD11c was also present on a sub-population of peripheral blood B cells.

Animals↗
PubMed1995

Analysis of the fine specificities of sheep major histocompatibility complex class II-specific monoclonal antibodies using mouse L-cell transfectants.

The fine specificities of two panels of monoclonal antibodies (mAbs) for sheep major histocompatibility complex (MHC) class II molecules were determined using five mouse L-cell transfectants, each expressing a defined sheep DQ or DR MHC class II A/B gene pair. Using the transfectants in an indirect fluorescence antibody assay, previous immunochemical characterization of the mAbs was confirmed for 16 of 23 mAbs tested. The MHC class II subtype specificity (DQ or DR) of each mAb was assigned without interference from the products of other expressed class II loci. This allowed the identification of both cross-locus specificities as well as defining fine specificities of mAbs previously only partially characterized by immunochemical techniques.

Amino Acid Sequence↗
PubMed1995

Discrimination between major histocompatibility complex class II DQ and DR locus products in cattle.

We have used a panel of anti-major histocompatibility complex (MHC) class II monoclonal antibodies (mAbs) and have assessed their specificity for the products of the individual bovine MHC (BoLA) class II subregions. The mAbs identified two distinct class II molecules by affinity purification and ELISA. Two-dimensional immunoblotting confirmed these data and NH2-terminal sequencing of the purified class II alpha chains of one member of each group identified the subregion specificity of the mAbs. The mAbs VPM36, TH22A and TH81A are specific for BoLA DQ, whereas VPM54, TH14B and J11 are specific for BoLA DR. SW73.2 reacts with both MHC subgroups of all cattle tested.

Amino Acid Sequence↗
PubMed1995

T cell activation by Theileria annulata-infected macrophages correlates with cytokine production.

A major feature of the pathology induced by Theileria annulata is acute lymphocytic proliferation, and this study investigates the mechanisms underlying the intrinsic ability of T. annulata-infected monocytes to induce naive autologous T cells to proliferate. Different T. annulata-infected clones expressed different but constant levels of MHC class II, varying from < 1.0 x 10(5) to 1.5 x 10(6) molecules/cell, as measured by saturation binding. However, no correlation was found between the level of MHC class II expression and levels of induced T cell proliferation. Theileria annulata-infected cell lines and clones were assayed for cytokine mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). The infected cells assayed produced mRNA specific for IL-1 alpha, IL-1 beta, IL-6, IL-10 and tumour necrosis factor-alpha (TNF-alpha), but not IL-2 or IL-4. One clone (clone G) did not produce mRNA for TNF-alpha. The degree of T cell proliferation induced by infected cells was directly correlated with the amount of mRNA produced for the T cell stimulatory cytokines IL-1 alpha and IL-6, as assessed by a semiquantitative technique. In contrast, cells infected with the related parasite T. parva produced mRNA for IL-1 alpha, IL-2, IL-4, IL-10 and interferon-gamma (IFN-gamma). Since T. parva-infected cells also induce naive autologous T cell proliferation, it seems likely that the production of IL-1 alpha by cells infected with either parasite is a major signal for the induction of non-specific T cell proliferation.

Animals↗
PubMed1995

Initial lentivirus-host interactions within lymph nodes: a study of maedi-visna virus infection in sheep.

Reactive changes occurring within lymph nodes draining the subcutaneous site of acute infection with maedi-visna virus (MVV) were studied, and the appearance of infected cells correlated with the immune response. Cells infected with virus were detected in the node by cocultivation from day 4 postinfection (p.i.), with maximum numbers being seen between days 7 and 14, but even then infected cells were rare, with a maximum frequency of 23 50% tissue culture infective doses (TCID50) in 10(6) lymph node cells. At later times, infected cells were still detected, but their numbers fell to 1 to 2 TCID50 per 10(6) cells. Virus-specific CD8+ cytotoxic T-cell precursors (CTLp) were isolated from infected nodes from day 10 p.i. onwards, and T-cell proliferative responses to MVV were first detected on day 7 and consistently detected after day 18. Histological analysis showed a vigorous immune response in the node. There was a marked blast reaction in the T-cell-rich zones, which was greatest at the time when the number of virally infected cells was at its height. At this stage, large numbers of plasma cells were seen in the medullary cords, indicating that extensive T-cell-dependent B-cell activation was occurring in the T-cell-rich zones. Germinal centers were prominent shortly after the onset of the T-zone response and were still present at 40 days p.i. Phenotype studies of isolated lymph node cells failed to detect major changes in the proportion or phenotype of macrophages, CD1+ interdigitating cells, and CD4+ or CD8+ T cells despite the fact that CD8+ lymphoblasts form a major population leaving the node in efferent lymph. This suggests that there is a balanced increase in the number of all cell types in response to the virus within the node and selective migration of CD8+ lymphoblasts containing virus-specific CTLp from the node. Virus-specific immune responses are therefore present within the node when infectious virus isolation is maximal, but cellular immunity may act to control the level of infection from day 18 onwards.

Animals↗
PubMed1995

Operative site bacteriology as an indicator of postoperative infectious complications in elective colorectal surgery.

Toward the completion of elective colorectal operations, 75 patients had qualitative aerobic and anaerobic cultures of specimens obtained from peritoneal irrigation fluid, anastomoses sites, and abdominal wound irrigation fluid to determine if a correlation exists between intraoperative flora and postoperative infectious complications. Patients enrolled in this prospective study received a mechanical bowel prep and a 12-18 hour course of perioperative intravenous antibiotics. Comparisons were made between the 60 (80%) patients who had no postoperative infections and the 15 (20%) who developed postoperative infectious complications (9 wound infections, 6 intraabdominal infections). There were significantly more low anterior resections in patients who developed postoperative infection compared to those who had no postoperative infection (26% vs 2%), while there were more colocolostomies in the group with no infections (38% vs 7%). Streptococcus spp., Bacteroides fragilis group, and Escherichia coli were the most commonly isolated organisms from each of the three sites sampled. Isolation of > or = 3 organisms from incisional wound cultures (P = 0.017) and < or = 4 organisms from peritoneal irrigation (P = 0.009) or anastomotic culture (P = 0.004) correlated with development of postoperative infectious complications. Thus, patients with infectious complications had significantly more isolates than those without infectious complications, and were more likely to have had a low anterior resection. These data suggest that future clinical studies should reexamine the duration of perioperative antimicrobials based on early laboratory reports of qualitative and quantitative operative site bacteriology.

Abdomen↗
PubMed1995

Neurologic and developmental outcome in treated congenital toxoplasmosis.

BACKGROUND: Earlier studies have shown that infants with untreated congenital toxoplasmosis and generalized or neurologic abnormalities at presentation almost uniformly develop mental retardation, seizures, and spasticity. Children with untreated subclinical disease at birth have developed seizures, significant cognitive and motor deficits, and diminution in cognitive function over time. OBJECTIVE: To determine neurologic, cognitive, and motor outcomes for children with congenital toxoplasmosis who were treated for approximately 1 year with pyrimethamine and sulfadiazine. DESIGN AND METHODS: Systematic, prospective, and longitudinal neurologic, cognitive, and motor evaluations were performed for 36 individuals with congenital toxoplasmosis. These infants were born between December 1981 and January 1991 and were treated with pyrimethamine and sulfadiazine for approximately 1 year beginning in the first months of life. Compliance with medications was documented. These individuals were evaluated in a standardized manner in a single center in the first months of life and at approximately 1, 3.5, 5, 7.5, and 10 years of age. Their cognitive function was compared with the cognitive function of a nearest-age, same-sex sibling when such siblings older than 3.5 years were available for study. RESULTS: Signs of active central nervous system infection (eg, cerebrospinal fluid [CSF] pleiocytosis, hypoglycorrhachia, elevated CSF protein, and, in some instances, seizures and motor abnormalities) resolved during therapy. Six of the 36 children had perinatal seizures. Four had their anticonvulsant therapy discontinued successfully within the first months of life, and two additional children developed new seizures at 3 and 5 years of age. Tone and motor abnormalities resolved by 1 year of age in 12 of 20 infants who exhibited abnormalities of tone and motor function at their initial neonatal evaluation. By February 1992, 29 of the 36 children had been evaluated when they were 1 year old, and 23 (79%) had a mean +/- standard deviation Mental Developmental Index (MDI) of 102 +/- 22 (range, 59 to 140). Six (21%) had a measure of their cognitive function that was less than 50. Results of sequential IQ tests, performed at 1.5 year intervals or greater, did not differ significantly over time (P > .05). Seven children with MDIs greater than 50 were compared with sibling controls; they had scores of 87 +/- 11 (range, 68 to 97) and their siblings had scores of 112 +/- 15 (range, 85 to 132) (P = .008). Seventeen of 18 children without hydrocephalus and six of eight children with obstructive hydrocephalus responsive to shunting had normal or near-normal neurologic and developmental outcomes. Children with hydrocephalus ex vacuo present at birth, with high CSF protein, and with lack of response to shunting have done less well. CONCLUSIONS: Neurologic and developmental outcomes were significantly better for most of these treated children than outcomes reported for untreated children or those treated for only 1 month (P < .001). Although the level of cognitive function for treated children was less than for their uninfected siblings (P < .008), there was no significant deterioration in neurologic and cognitive function of the treated children tested sequentially. These favorable treatment outcomes justify systematic identification and treatment of pregnant women with acute gestational Toxoplasma infection and young infants with congenital toxoplasmosis.

Child Development↗
PubMed1994

Sequence of the sheep interleukin-10-encoding cDNA.

The ovine interleukin-10 (oIL-10)-encoding cDNA has been cloned and sequenced using gene amplification by the polymerase chain reaction (PCR). We present the complete coding sequence of the ovine IL-10 gene, as well as the predicted amino acid (aa) sequence. The oIL10 DNA coding sequence is 531 nucleotides long and the mature protein product is predicted to be 18,367 Da, consisting of 158 aa, excluding a 19-aa N-terminal hydrophobic signal peptide. The oIL-10 protein is > 77% identical to pig and human IL-10, > 71% identical to rodent IL-10 and > 68% identical to viral IL-10.

Amino Acid Sequence↗
PubMed1994

Interleukin-1 receptor expression by ovine afferent lymph dendritic cells: response to secondary antigen challenge.

Interleukin (IL)-1 is thought to enhance the function of antigen presenting cells of the dendritic cell lineage. To investigate the interaction of IL-1 and dendritic cells recombinant ovine IL-1 alpha and IL-1 beta have been used to determine IL-1 receptor (R) expression on fresh dendritic cells (ALDC) collected from cannulated sheep pseudoafferent lymph ducts, both prior to and in response to localized ovalbumin challenge. Resting ovine ALDC express approximately 510 IL-1R per cell for IL-1 alpha (Kd approximately 30 pM) and approximately 350 IL-1R/cell for IL-1 beta (Kd approximately 160 pM). Saturation binding and in situ analyses show an initial transient but dramatic increase in IL-1 alpha binding to ALDC by 4 h in response to ovalbumin challenge of primed sheep. Maximal IL-1R expression, reaching > or = 21700 IL-1R/cell for IL-1 alpha detected by around 48 h, was followed by a gradual return to resting level by 8 days post challenge. Fewer than 0.5% of resting ALDC expressed IL-1R but at least 5% of ALDC bound IL-1 alpha after ovalbumin challenge. There was no evidence of specific up-regulation of receptors for IL-1 beta on these cells. Fresh ovine alveolar macrophages, used as a positive control for specific IL-1R expression, were found to express approximately 2600 sites/cell for IL-1 alpha (Kd approximately 56 pM) and 16,500 sites/cell for IL-1 beta (Kd approximately 4.6 pM). In view of the differing IL-1 binding characteristics displayed by the receptors on the two cell types, it is postulated that afferent lymph dendritic cells and macrophages are not expressing the same form of IL-1R.

Animals↗
PubMed1994

Classification of CEA-related positivity in primary and metastatic malignant melanoma.

Using a panel of antibodies to carcinoembryonic antigen (CEA), in paraffin-processed biopsy material patchy, predominantly membranous positivity was seen on tumour cells in 70 per cent of cases of superficial spreading melanoma, 60 per cent of nodular melanomas, and 75 per cent of secondary deposits studied with unabsorbed polyclonal anti-CEA only. No staining was seen using monoclonal anti-CEAs. Localization of CEA to the cell membrane was confirmed with confocal microscopy. Immunoblotting of fresh frozen material detected CEA of around 180 kD in both primary and metastatic melanomas migrating with an apparent molecular weight of between 150 and 200 kD, indicating variable glycosylation of the protein. Recognition of an adhesive role for CEA with roles in immunolocalization and immunotherapy emphasizes the importance of more precise classification of CEA-related positivity in human tumours.

Carcinoembryonic Antigen↗
PubMed1994

Early stages of infection with Trypanosoma congolense: parasite kinetics and expression of metacyclic variable antigen types.

Trypanosoma congolense develops in the skin of sheep at the site of inoculation of metacyclic trypanosomes, forming a chancre containing large numbers of parasites. By cannulating the afferent and efferent lymphatic ducts draining the skin and regional lymph node, the progressive development and migration of trypanosomes from the chancre was monitored and the expression of metacyclic antigen types (M-VATs) was determined. The kinetics of development of parasitosis in the afferent and efferent lymph was similar. Trypanosomes were detected in lymph 5 to 6 days after the inoculation of cultured metacyclic trypanosomes, at the same time as the chancre first appeared in the skin. The numbers of trypanosomes in the lymph reached their peak levels 8 to 10 days post infection and thereafter numbers fell, although there were still parasites in the lymph after the chancre had regressed. Trypanosomes in the afferent lymph expressed mainly M-VATs and the absolute numbers of four M-VATs which were monitored increased up to 9 days post infection. There was a fall in numbers by day 10, but 92% of the trypanosomes in the afferent lymph continued to express M-VATs. In contrast, trypanosomes from the efferent lymph were found not to express M-VATs suggesting that a major switch in VAT expression occurs in the lymph node. Specific antibody responses, measured by neutralization tests, were evident 16 to 20 days after infection in afferent lymph but only low levels of antibodies were found in efferent lymph.

Animals↗