Search PubMed⌕ Search

Biomedical subjects

J Hopkins

Publications and source records attributed to J Hopkins.

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

Differential expression of ovine CD1.

was examined using a combination of reverse transcription-polymerase chain reaction (RT-PCR) with sequence-specific primers and Northern and in situ hybridization techniques. The aim of the study was to establish the patterns of CD1 expression at the molecular level and address questions posed by previous studies in other species regarding expression patterns of CD1. A 'pan-CD1' probe based on the exon 4 (alpha 3) region was used in addition to isotype-specific probes for SCD1B (the exon 3 region of clone SCD1B42) and SCD1D (the exon 3 region of clone SCD1D). Widespread expression of CD1 (including thymus, peripheral blood lymphocytes, lung and intestine) was identified using both the exon 4 and SCD1D probe. SCD1B expression was more restricted, being identified in equivalent levels only in the thymus and in scattered populations of dendritic cells. These results highlight the difference in expression patterns between group 1 and group 2 CD1 family members and establish SCD1D as the CD1 family member with the widest pattern of expression, consistent with a differential role for the different CD1 family members.

Animals↗
PubMed2000

Promoting mental health after childbirth: a controlled trial of primary prevention of postnatal depression.

OBJECTIVES: To investigate the effectiveness of a psychosocial intervention for the prevention of postnatal depression. DESIGN: A controlled trial. METHOD: Women expecting their first or second child and designated as 'more vulnerable' by the Leverton Questionnaire (LQ) or Crown Crisp Experiential Index (CCEI) were allocated to a preventive intervention (N = 47) or control group (N = 52) by expected date of delivery to provide groups expecting their babies around the same time. Women were assessed at 3 months postnatal. An additional group of women designated as 'less vulnerable' (N = 88) were assessed to confirm the validity of the LQ as a vulnerability measure. RESULTS: Questionnaire measures of mood in first-time mothers invited to the Preparation for Parenthood groups revealed significantly more positive mood than in the group receiving routine care. The median Edinburgh Postnatal Depression Scale (EPDS) score for those invited was 3, compared to 8 for those not invited (p < .005). The diagnosis of depression using the Present State Examination revealed differences for both groups, though it reached statistical significance only with the first-time mothers. Only 19% of the 'more vulnerable' invited first-time mothers were 'borderline' or 'cases' at any time in the first 3 months postnatally compared to 39% of those not invited. The Surviving Parenthood groups for second-time mothers were not successful. CONCLUSION: Some depressions following childbirth can be prevented by brief interventions that can be incorporated with existing systems of antenatal classes and postnatal support groups.

Adult↗
PubMed1999

Analysis of reporter gene expression in ovine dermis and afferent lymph dendritic cells in vitro and in vivo.

Plasmid DNA administration has revolutionised approaches to vaccination, and many studies have demonstrated the generation of both humoral and cytotoxic T cell responses which confer protection against live pathogen challenge. However, the mechanisms underlying DNA vaccination are poorly understood. Several studies have suggested the involvement of professional antigen presenting cells such as dendritic cells (DC), but direct evidence for this is lacking. We have used the pseudoafferent lymphatic cannulation model in sheep to study the expression of a plasmid encoding enhanced green fluorescent protein (EGFP) by afferent lymph DC following administration to skin. The cells were analysed by flow cytometry. Preliminary studies were carried out to determine if the pEGFP would function in sheep cells in vitro. The results showed that electroporation of sheep skin fibroblasts, primary macrophages, and afferent lymph DC with 30 microg pEGFP resulted in varying degrees of fluorescence in these cells e.g. 35% of skin cells examined at 48 h, and 7% of afferent lymph DC examined after 4 h. Following intradermal injection of 120 microg of pEGFP, small numbers of fluorescent DC (1-5%) were evident by flow cytometry after 1-4 h. The fluorescent DC continued to drain into the lymphatics over a period of 24 h. Analysis by PCR showed that free pEGFP appeared in the afferent lymph plasma within 1 h of injection, peaking at 2 h and becoming undetectable after 6 h. The results suggest that primary immune responses may be initiated by uptake of soluble protein antigen by afferent lymph DC and by free plasmid rapidly draining to the lymphatics where it may be taken up by DC in the lymph plasma and the local lymph node.

Animals↗
PubMed1999

Amino-terminal sequencing of sheep CD1 antigens and identification of a sheep CD1D gene.

The anti-CD1 monoclonal antibodies IAH-CC14 and SBU-T6 were used to immunopurify CD1 antigens from sheep thymocytes. The amino-terminal sequence of IAH-CC14 yielded 13 amino acids, and 29 amino acids were obtained from the SBU-T6 antigen. The sequence of the IAH-CC14 antigen was 100% identical to the predicted sequence of the sheep CD1B clone, SCD1B-42. The 29 amino acid sequence of the SBU-T6 antigen did not match identically with the derived amino acid sequence of any of the previously reported sheep CD1 genes but had closest similarity to the derived sequence of human CD1E. Degenerate polymerase chain reaction primers based on this sequence identified a group 2 sheep CD1 gene. The predicted amino acid sequence of this gene shows that it is not identical to the SBU-T6 peptide, indicating that a different, CD1D-like gene was cloned.

Amino Acid Sequence↗
PubMed1999

Changes in peripheral blood lymphocyte subpopulations and parasite-specific antibody responses in Trypanosoma evansi infection of sheep.

This paper reports on changes in the lymphocyte composition of the peripheral blood in sheep infected with Trypanosoma evansi. In addition, parasite-specific IgG1 and IgM antibody responses were monitored using a double-sandwich enzyme-linked immunosorbent assay (ELISA) technique. Eight sheep were infected with 2 x 10(6) T. evansi TREU 2143. The infection was characterised by chronicity and ended in self-cure in two of the sheep. These two sheep were designated group A, whereas the other six sheep, which remained parasitaemic until treated, were designated group B. Analysis of the peripheral blood lymphocytes (PBLs) by indirect immunofluorescence staining and flow cytometry revealed significant alterations in the numbers of T- and B-cell subsets detected in all infected sheep. In group A, whereas the numbers of CD8+ cells decreased, CD4+ cells showed marginal decreases, remaining at or above pre-infection figures and resulting in increase in the CD4:CD8 ratio. In group B, CD8+ cells showed few marginal decreases, being at or above pre-infection figures most of the time, whereas CD4+ cells decreased significantly from day 26 post infection (p.i.) such that the CD4:CD8 ratio decreased. Infection also resulted in significant increases (P < 0.001) as of day 26 p.i. in circulating B-cells in group B as shown by the numbers of sIg+, CD45R+, CD1+ and major histocompatibility complex (MHC) II+ cells. The increases, however, were moderate and biphasic in group A. T. evansi-specific IgM and IgG1 antibody isotypes were detected in all infected sheep, but their levels were significantly higher in group A than in group B (IgM P < 0.05; IgGI P < 0.01). In addition, although an initially higher level of IgM response was subsequently replaced by a higher level of IgG1 response in group A, this was never the case in group B until after drug treatment.

Animals↗
PubMed1999

A prospective evaluation of PTFE graft patency and surveillance techniques in hemodialysis access.

The purpose of this study was to perform a prospective multicenter evaluation of the patency, complications, and predictive factors of patency for 6-mm expanded polytetrafluoroethylene (ePTFE) grafts used in hemodialysis access. Eighty-six patients were evaluated; the mean age was 55.8 years (range 23-90), 46 patients were female. Patency and complications were assessed at the initial dialysis and 1, 3, 6, 9, and 12 months postoperatively. Kaplan-Meier survival curves were calculated to determine primary and secondary patency, and log-rank analysis was used to determine differences between curves. The Student's t-test was used to compare groups. Primary and secondary patency rates at 1 year were 43% and 64%. Venous line pressures tended to rise over time. Recirculation values and blood flow rates during dialysis showed no correlation to graft patency. These results show that ePTFE provides a suitable secondary choice for vascular access for end-stage renal disease patients in whom an autogenous fistula is not possible. Thrombosis and anastomotic stenosis are common and should be aggressively identified and treated to prolong overall graft survival.

Arteriovenous Shunt, Surgical↗
PubMed1999

The plastid in Plasmodium falciparum asexual blood stages: a three-dimensional ultrastructural analysis.

The plastid in Plasmodium falciparum asexual stages is a tubular structure measuring about 0.5 micron x 0.15 micron in the merozoite, and 1.6 x 0.35 microns in trophozoites. Each parasite contains a single plastid until this organelle replicates in late schizonts. The plastid always adheres to the (single) mitochondrion, along its whole length in merozoites and early rings, but only at one end in later stages. Regions of the plastid are also closely related to the pigment vacuole, nuclear membrane and endoplasmic reticulum. In merozoites the plastid is anchored to a band of 2-3 subpellicular microtubules. Reconstructions show the plastid wall is characteristically three membranes thick, with regions of additional, complex membranes. These include inner and outer membrane complexes. The inner complex in the interior lumen is probably a rolled invagination of the plastid's inner membrane. The outer complex lies between the outer and middle wall membranes. The interior matrix contains ribosome-like granules and a network of fine branched filaments. Merozoites of P. berghei and P. knowlesi possess plastids similar in structure to those of P. falciparum. A model is proposed for the transfer of membrane lipid from the plastid to other organelles in the parasite.

Animals↗
PubMed1999

Immune cell populations in the equine corpus luteum throughout the oestrous cycle and early pregnancy: an immunohistochemical and flow cytometric study.

Recent evidence indicates that the cells of the immune system and their large network of secretory products, or cytokines, play an active role in the ovary throughout the oestrous cycle. In the present study, immune cell populations (T and B lymphocytes, macrophages, granulocytes and eosinophils) and expression of major histocompatibility complex (MHC) class II were investigated in corpora lutea from mares in early (days 2-4), mid- (days 7-10) and late (days 12-14) dioestrus, the post-luteolytic phase (days 16-17) and early pregnancy. The number of T lymphocytes within the corpus luteum increased in the late luteal phase. CD4+ cells did not increase until day 16, whereas the number of CD8+ cells increased before functional luteolysis; an apparently selective luteal infiltration of CD8+ cells was observed. MHC class II expression by non-steroidogenic cells was increased in samples from days 16-17, as was the number of infiltrating macrophages. Flow cytometry revealed very low expression of MHC class II by large luteal cells at all stages of the oestrous cycle. In early pregnancy, the number of CD4+ and CD8+ cells and macrophages decreased, as did MHC class II expression, compared with mid-dioestrous samples. B cells were present in very small numbers in all samples examined. Eosinophils were similarly sparsely distributed and numbers decreased further in pregnancy. After exogenous PGF2 alpha administration, populations of CD4+ cells and non-specific esterase staining cells were significantly smaller than after natural luteolysis, whereas eosinophil numbers were increased compared with samples from days 16-17. However, the number of CD8+ and CD5+ cells and MHC class II expression were not significantly different from those observed after natural luteolysis. These findings indicate that populations of immune cells in the equine corpus luteum vary during its lifespan. The selective increase in CD8+ cells before functional luteolysis indicates that they have a physiological role in the regression of the corpus luteum.

Animals↗
PubMed1998

Genomic organization and partial duplication of the human alpha7 neuronal nicotinic acetylcholine receptor gene (CHRNA7).

The human alpha7 neuronal nicotinic acetylcholine receptor gene (HGMW-approved symbol CHRNA7) has been characterized from genomic clones. The gene is similar in structure to the chick alpha7 gene with 10 exons and conserved splice junction positions. The size of the human gene is estimated to be larger than 75 kb. A putative promoter 5' of the translation start in exon 1 has been cloned and sequenced. The promoter region lacks a TATA box and has a high GC content (77%). Consensus Sp1, AP-2, Egr-1, and CREB transcription factor binding sites appear to be conserved between bovine and human genes. The alpha7 nAChR gene was found to be partially duplicated, with both loci mapping to the chromosome 15q13 region. A yeast artificial chromosome contig was constructed over a genetic distance of 5 cM that includes both alpha7 loci and the region between them. Four novel exons are described, located in genomic clones containing the partially duplicated gene. The duplicated sequences, including the novel exons, are expressed in human brain.

Base Sequence↗
PubMed1998

Further investigation of a chromosome 15 locus in schizophrenia: analysis of affected sibpairs from the NIMH Genetics Initiative.

Linkage of a neurophysiological deficit associated with schizophrenia, i.e., the failure to inhibit the auditory P50 response, was previously reported at chromosome 15q14. The marker with the highest pairwise lod score, D15S1360, was isolated from a yeast artificial chromosome containing a candidate gene, the alpha7-nicotinic acetylcholine receptor gene. In the present study, this linkage was further investigated in a subset of the NIMH Genetics Initiative schizophrenia families. These families have not been studied neurophysiologically, as were the families in the original report. Therefore, the DSMIII-R diagnosis of schizophrenia was used as the affected phenotype. Twenty families fulfilled the criteria of at least one sibpair concordant for schizophrenia, along with their two parents or another affected relative outside the nuclear family, available for genotyping. Sibpair analysis showed a significant proportion of D15S1360 alleles shared identical-by-descent (0.58; P < 0.0024). The results further support the involvement of this chromosomal locus in the genetic transmission of schizophrenia.

Chromosomes, Human, Pair 15↗
PubMed1998

MR imaging contrast enhancement based on intermolecular zero quantum coherences.

A new method for magnetic resonance imaging (MRI) based on the detection of relatively strong signal from intermolecular zero-quantum coherences (iZQCs) is reported. Such a signal would not be observable in the conventional framework of magnetic resonance; it originates in long-range dipolar couplings (10 micrometers to 1 millimeter) that are traditionally ignored. Unlike conventional MRI, where image contrast is based on variations in spin density and relaxation times (often with injected contrast agents), contrast with iZQC images comes from variations in the susceptibility over a distance dictated by gradient strength. Phantom and in vivo (rat brain) data confirm that iZQC images give contrast enhancement. This contrast might be useful in the detection of small tumors, in that susceptibility correlates with oxygen concentration and in functional MRI.

Animals↗
PubMed1998

Increase in CD5+ B cells and depression of immune responses in sheep infected with Trypanosoma evansi.

The effects of Trypanosoma evansi on the cellular and humoral immune responses of sheep to Pasteurella haemolytica vaccine were studied. Peripheral blood lymphocytes (PBLs) from the sheep were analysed using single and double-colour indirect immunofluorescence staining and flow cytometry to monitor changes in circulating B and T cell subsets. Serum antibody responses were assayed using the enzyme-linked immunosorbent assay technique (ELISA), in addition to measuring local skin reactions at the site of vaccine administration. Results showed significant increases in circulating B cells in all sheep after the primary (p < 0.01) and secondary (p < 0.001) vaccinations although the increases were much more dramatic in the T. evansi-infected sheep. In addition, infection induced significant increases (p < 0.004) both in proportions and numbers of CD5+ B cells with more than 70% of circulating B cells expressing the CD5 antigen and showed significant differences (p < 0.01) from those of control sheep in which vaccination alone failed to induce similar increases. Also, infection resulted in significant decreases in CD5+ (p < 0.003), CD4+ (p < 0.03) and CD8+ (p < 0.03) T cell subsets in contrast to their increases in all control animals after vaccination. Moreover, there were significant suppression of both local skin reaction (p < 0.005) and serum Ig and IgG1 (p < 0.001) antibody responses to the vaccine antigen.

Animals↗