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Biomedical subjects

N Miller

Publications and source records attributed to N Miller.

At least 127 records · Page 7Linked to original sources
PubMed1993

CD3 antigen-mediated calcium signals and protein kinase C activation are higher in CD45R0+ than in CD45RA+ human T lymphocyte subsets.

T lymphocytes may be separated into subsets according to their expression of CD45 isoforms. The CD45R0+ T cell subset has been reported to proliferate in response to recall antigen and to mitogenic mAb to a much greater extent than the CD45RA+ subset. This difference could be due to more efficient coupling of the T cell antigen receptor complex to mitogenic signaling pathways. To investigate this possibility, CD3 antigen-induced calcium signals, diacylglycerol (DAG) production and protein kinase C (PKC) activation levels were compared in CD45RA+ and CD45R0+ human T lymphocyte subsets derived from peripheral blood. The mean CD3-induced rise in intracellular calcium was 80% greater in CD45R0+ than in CD45RA+ cells. Basal DAG levels in CD45R0+ cells were found to be, on average, 60% higher than in CD45RA+ cells (p = 0.002), but the CD3-induced production of DAG over background was not different in the two subsets (p = 0.4). Basal PKC activity, and CD3-induced PKC activation levels over background, were found to be 50% and 140% higher, respectively, in CD45R0+ cells than in CD45RA+ cells (p = 0.015 and 0.023). The CD45R0+ subset contained a higher proportion of cells expressing activation markers, such as CD25, CD71 and major histocompatibility complex class II, when compared to the CD45RA+ subset. Our results suggest that the elevated basal DAG levels observed in the CD45R0+ subset may reflect the recent activation of these cells. Both the higher basal DAG and CD3-induced elevation in intracellular calcium observed in the CD45R0+ cells may contribute to the greater PKC activation signals triggered by CD3 mAb in this subset. These findings elucidate the greater response of CD45R0+ T cells to mitogenic stimuli compared to CD45RA+ cells.

Adult↗
PubMed1993

Acute hepatitis B infection in aboriginal Australians.

The apparent incidence of acute hepatitis B infection in the Top End of the Northern Territory was estimated from notification data and hospital data to be 12 per 100,000 per year, with a marked difference between Aborigines (42 per 100,000) and non-Aborigines (4 per 100,000), and an odds ratio of 9.7 (95 per cent confidence intervals 3 to 33). Sixty percent of Aboriginal cases of acute hepatitis B occurred in children under 10 years of age, whereas non-Aboriginal cases occurred in adults aged 20 to 29, most with behavioural risk factors. These findings confirm the importance of immunising Aboriginal children to reduce the future incidence of hepatitis B infection and hepatoma.

Acute Disease↗
PubMed1993

Reconstitution of severe combined immunodeficient mice with intrathyroidal lymphocytes of thyroid xenografts from patients with Hashimoto's thyroiditis.

Thyroid tissues from patients with Hashimoto's thyroiditis (HT) have been xenografted to both severe combined immunodeficiency (SCID) mice and nude mice to study the intrathyroidal lymphocytes which were expected to migrate from the xenografts in the SCID mice. Peripheral blood mononuclear cells from HT, Graves' disease, and normal donors have also been separately engrafted. SCID mice, but not nude mice with HT thyroid grafts produce human immunoglobulins. More immunoglobulin G (IgG), but less IgM and IgA is produced in SCID mice with HT thyroid grafts (SCID-TH), compared to SCID mice injected with peripheral blood mononuclear cells from patients with HT or normal donors (SCID-PB), suggesting that different B cell subpopulations were active in the SCID-PB vs. SCID-TH. Production of IgG by SCID-PB and SCID-TH was maintained 6 weeks after engraftment, and decreased thereafter. SCID mice but not nude mice grafted with HT thyroid tissue produce antibodies to thyroglobulin and thyroperoxidase. Lymphocytes within intact HT thyroid grafts persist in SCID mice, and migrate to the spleen, whereas human lymphocytes do not survive in the thyroid grafts or other tissues of the nude mouse. In 6 weeks, the xenografts in nude mice became histologically normal. In contrast, xenografts from SCID mice showed more marked inflammatory changes than in the original human lesion, although the ratio of T/B cells is unchanged. This worsening of the lesion may relate to the increase in activation of the T-lymphocytes.

Animals↗
PubMed1993

Studies of thyroid xenografts from Graves' disease in severe combined immunodeficient mice.

Thyroid tissues from normal (paranodular) subjects and patients with Graves' disease (GD) and Hashimoto's thyroiditis (HT) were xenografted to severe combined immunodeficiency (SCID) mice, and the same tissues were engrafted into nude mice; in addition, peripheral blood mononuclear cells were engrafted to separate SCID mice (SCID-PB). Thyroglobulin (TG) and microsomal antibodies (Abs) became detectable with high titers by hemagglutination assays in SCID mice xenografted with thyroid tissues (SCID-TH) from GD and HT patients; moreover, TG Ab was detectable even in SCID-TH from TG Ab-negative GD and HT donors. On the other hand, only 2 of 10 SCID-PB had detectable Abs with low titers. TSH receptor (TSH-R) Ab was detectable in all sets of SCID-TH from GD. After peaking (3-7 weeks), their levels decreased despite the fact that immunoglobulin G levels increased. In addition, in 3 of 4 sets of SCID-PB from GD patients, TSH-R Ab was also detectable. SCID-TH from GD and HT patients showed transient hyperthyroxinemia, peaking at 2 weeks; these values were significantly higher [free T4, 6.48 +/- 0.90 and 5.50 +/- 0.77 pmol/L (mean +/- SE), respectively; P < 0.05] than SCID-TH from normal controls (2.5 +/- 0.24). Histologically, intrathyroidal infiltrating lymphocytes (ITL) survived in SCID mice, but not in nude mice after 8 weeks. The follicles of GD tissue in SCID mice were virtually destroyed with ITL, and their appearance was similar to that in HT. In conclusion, TSH-R Ab was clearly produced from ITL, and some peripheral blood mononuclear cells grafts could also produce TSH-R Ab. In spite of the presence of TSH-R Ab, SCID-TH from GD patients did not show persistent hyperthyroxinemia, presumably because destructive thyroiditis may be occurring in the grafted tissue, with decreasing levels of TSH-R Ab.

Animals↗
PubMed1993

Identifying blood group antibodies...can a computer help?

Antibody identification is one of the last areas of laboratory medicine to embrace computerization. This is due in part to the complex nature of antibody identification. Until recently, computer programs written to assist with antibody identification have been slow and cumbersome. However, technological advances in computer hardware have greatly improved the response time for these applications. Still, blood bank technologists sometimes shun assistance from the computer because they consider anti- body investigation as an intellectually stimulating aspect of their job that they do not wish to turn over to a computer. Computer programs for antibody investigation are probably most useful for technologists who perform antibody investigations infrequently. They can also be invaluable for experienced technologists performing complex investigations. When integrated with a computerized blood bank record-keeping system, antibody investigation software can improve storage and retrieval of test results. Database applications for retrieving rare cells and sera offer the potential to improve the productivity and capability of any anti- body investigation laboratory. And word processing applications greatly enhance the potential for generating meaningful reports of test results.

Journal Article↗
PubMed1992

Epstein-Barr virus enters B cells and epithelial cells by different routes.

Epstein-Barr virus (EBV) infects two cell types, B lymphocytes and epithelial cells. Electron microscopic studies have shown that the virus fuses with the lymphoblastoid cell line Raji but is endocytosed into thin-walled non-clathrin-coated vesicles in normal B cells before fusion takes place. To compare early interactions of EBV with epithelial cells and B cells, a fluorescence dequenching assay of fusion was employed, using virus labeled either with the pH-insensitive probe octadecyl rhodamine B chloride (R18) or with 5(N-octadecanoyl) aminofluorescein (AF), which loses emission intensity at a pH below 7.4. Fusion of virus labeled with R18 could be monitored with B cells, Raji cells, and epithelial cells. Lowering the extracellular pH or pretreatment of cells with ammonium chloride or methylamine had no effect on these measurements. In contrast, fusion of virus labeled with AF could be measured with Raji cells and epithelial cells, but not with normal B cells unless cells were previously treated with ammonium chloride. Fusion of virus with normal B cells was inhibited with chlorpromazine, chloroquine, and sodium azide, but none of these reagents had any effect on fusion with Raji or epithelial cells. These results suggest that entry of EBV into nonpolarized suspensions of epithelial cells occurs by fusion at the cell surface, that EBV may be incapable of fusing with normal B cells unless it has first been endocytosed, and that pH appears to be irrelevant to either event. A combination of the two probes, R18 and AF, may have general use for determining the sites of entry of enveloped viruses that fuse in a pH-independent manner.

Attachment Sites, Microbiological↗
PubMed1992

Quantitative and functional analyses of spleen and in situ islet immune cells before and after diabetes onset in the NOD mouse.

Cytofluorometric analysis using specific monoclonal antibodies directed against the T cell antigens Thy-1.2, CD4, CD8, CD4V beta(8.1 + 8.2 + 8.3), and the antigen Mac-1 expressed by mature macrophages and NK cells were used to characterize and quantify the phenotypes of (1) unfractionated and Percoll gradient fractionated in situ islet immune cells isolated from prediabetic and diabetic female NOD mouse spleens. We found in prediabetic female mice that the majority (approximately 70%) of the in situ islet immune cells were Thy-1.2 positive T cells. CD4 positive T cells (approximately 40%) were the most abundant phenotype together with double negative T cells (approximately 20%). The percentage of CD8 positive T cells were approximately 10%, and only approximately 4% of the immune cells were Mac-1 positive. The percentages of CD4V beta (8.1 + 8.2 + 8.3) positive and double negative T cells in diabetic spleens were significantly higher in comparison to prediabetic spleens. In C57B1/6J control nondiabetic mice the percentage of double negative T cells in the spleens was significantly 4-fold lower when compared to diabetic NOD spleens. The specific cytolytic activity mediated by in situ islet immune cells against 51Cr-labeled dispersed syngeneic single-cell islet cells at an effector to target ratio of 20 was twenty- to thirty-fold higher than that mediated by prediabetic splenic lymphoid cells. It is concluded that prediabetic NOD mouse in situ islet immune cells are mostly CD4 positive and double negative T cells, and that CD4 and CD8 positive T cells in the intra-islet infiltrate warrants further evaluation as potential effector T cells in target beta-cell destruction.

Animals↗
PubMed1991

Variant specific glycoprotein of Trypanosoma brucei consists of two domains each having an independently conserved pattern of cysteine residues.

The complete amino acid sequences for nine variant specific glycoproteins (VSGs) of Trypanosoma brucei are presented. These have more than doubled the size of the VSG sequence data base and have enabled a new and more rigorous comparison to be made between amino acid sequences of different VSGs. Each VSG can be defined as a combination of an N-terminal domain type and a C-terminal domain type, based on the distribution of cysteine residues within the molecule. This identifies three N-terminal domain types and at least four C-terminal domain types. Different combinations of N and C-terminal domains can be formed; for example, in the sequences presented here, two different N-terminal domains are found in association with each of three different C-terminal domains. The biological context of the domain structure of VSGs is discussed.

Amino Acid Sequence↗
PubMed1991

Model for studying virus attachment. II. Binding of biotinylated human T cell leukemia virus type I to human blood mononuclear cells potential targets for human T cell leukemia virus type I infection.

Purified human T cell leukemia virus type I (HTLV-I) was biotinylated and used to study its attachment to human PBMC. The use of biotinylated HTLV-I (biot-HTLV-I) in conjunction with mouse mAb specific for selected cell-surface molecules and flow cytometric analysis allowed us to positively identify virus-binding cells among a heterogeneous blood mononuclear cell population. Biot-HTLV-I efficiently bound not only to T cells, but also to B cells and monocytes. Preincubation of monocytes with excess of unlabeled HTLV-I significantly reduced the attachment of biot-HTLV-I. HTLV-I not only bound to, but also infected, B cells, as suggested by: i) in situ hybridization of a 35S-labeled full length HTLV-I DNA probe with EBV-transformed B cells, previously cocultured with HTLV-I-producing (G11MJ) T cells, and ii) hybridization of the same nick-translated 32P-labeled DNA probe with blotted DNA from similar HTLV-I-infected EBV-transformed B cells. HTLV-I infection did not affect the ability of B cells to secrete IgG. These findings suggest that HTLV-I cannot only infect cells of the T lineage, but can also infect B cells.

Antibody Formation↗
PubMed1991

Effects of recombinant human interleukin-2 and tumor necrosis factor-alpha with or without interferon-gamma on human thyroid tissues from patients with Graves' disease and from normal subjects xenografted into nude mice.

We have compared the effects of interleukin-2 (IL-2) or tumor necrosis factor-alpha (TNF alpha) administration with or without interferon-gamma (IFN gamma) on Graves' and normal thyroid tissue xenografts in the nude mouse (in the absence of an intact immune system) in terms of possible functional, immunological, or histological changes. The dosages of recombinant human IL-2, TNF alpha, and IFN gamma given to each mouse were 250, 800, and 4000 U, respectively; they were injected ip daily for 6 consecutive weeks. The parameters measured included the free T4 index, thyroid autoantibodies, and mouse TSH during the course of the study. Thyroid epithelial cell (TEC) HLA-DR expression was measured in thyroid tissue before xenotransplantation and at death; in addition, light microscopic studies were carried out at those times. There were no significant differences in thyroid function between the results in unstimulated (control) animals and those obtained with cytokine administration in either group of tissues, with the exception of the group receiving TNF alpha together with IFN gamma; in this latter group, the free T4 index declined significantly 4-6 weeks after commencement of treatment in the animals with normal thyroid tissue xenografts. The reduction of thyroid function induced by the combination of IFN gamma and TNF alpha observed in normal thyroid tissue may be due to inhibition of thyroperoxidase and thyroglobulin gene transcription. However, there was no such effect on the Graves' thyroid tissue xenografts, perhaps because of down-regulation of this tissue in response to cytokines, after having been released from long term in vivo immune stimulation. On the other hand, TNF alpha plus IFN gamma induced TEC HLA-DR expression on both types of thyroid xenografts at death, although IL-2 alone did not induce HLA-DR expression, and IFN gamma induced TEC significantly only on normal thyroid xenografts (but not on Graves' xenografts). In light microscopic examination, Graves' thyroid xenografts treated with IL-2 alone or TNF alpha plus IFN gamma appeared normal at death. In addition, normal thyroid xenografts treated with the same cytokines did not show discernible differences compared to those at human surgery or when the xenografts were untreated at death. We conclude that Graves' TEC did not differ from normal TEC in any significant fashion at the time of death, aside from a reduced responsiveness to the stimuli applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Transmetatarsal amputation: the role of adjunctive revascularization.

Over a 12-year period, 160 transmetatarsal amputations were performed in patients with peripheral vascular occlusive disease. The following groups were defined: group 1 - nonreconstructable disease (n = 40); group 2 - transmetatarsal amputation in conjunction with distal revascularization (n = 99); group 3 - reconstructable disease but transmetatarsal amputation performed without simultaneous revascularization (n = 21). There were nine early deaths in the entire series, for an operative mortality rate of 5.6%. The lowest rate of transmetatarsal amputation healing (24%) occurred in group 1. An 86% healing rate was achieved in group 3, but in seven cases (33%) some type of revascularization was required within 3 months of the amputation. In group 2 the healing rate was 62% but reached 83% where the bypass remained patent for at least 3 months after the amputation. Long-term patency rates also affected healing. Healing was not influenced by the number of local procedures (single vs multiple). The presence of severe infection or extensive necrosis necessitated open transmetatarsal amputation in 89 cases; the remaining 71 amputations involved primary closure. Since many patients were treated at a time when diagnostic modalities as well as the operative indications and techniques differed somewhat from the current practice, much of the information regarding group I patients in particular should be considered as a negative historical control and any conclusion from our data should be adjusted accordingly. Healing after amputation at the transmetatarsal level can be expected in the majority of instances in which revascularization can be performed with predictable patency, even when the standard criteria for performing such amputations are liberalized.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗