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Biomedical subjects

C O'Brien

Publications and source records attributed to C O'Brien.

At least 217 records · Page 12Linked to original sources
PubMed1990

A randomized, controlled trial of interferon alfa-2b alone and after prednisone withdrawal for the treatment of chronic hepatitis B. The Hepatitis Interventional Therapy Group.

BACKGROUND AND METHODS: Chronic hepatitis B is a common and often progressive liver disorder for which there is no accepted therapy. To assess the efficacy of treatment with interferon, we randomly assigned patients with chronic hepatitis B to one of the following regimens: prednisone for 6 weeks followed by 5 million units of recombinant interferon alfa-2b daily for 16 weeks; placebo followed by 5 million units of interferon daily for 16 weeks; placebo followed by 1 million units of interferon daily for 16 weeks; or observation with no treatment. RESULTS: Hepatitis B e antigen and hepatitis B viral DNA disappeared from serum significantly more often in the patients given prednisone plus interferon (16 of 44 patients, or 36 percent) or 5 million units of interferon alone (15 of 41; 37 percent) than in the untreated controls (3 of 43; 7 percent; P less than 0.001); the difference between those given 1 million units of interferon (7 of 41; 17 percent) and the controls was not significant. The strongest independent predictor of a response to treatment was the amount of hepatitis B viral DNA in serum at entry (P less than 0.0001). Of the 38 patients who responded to interferon, 33 (87 percent) had normal serum aminotransferase levels after therapy; 11 patients who responded (29 percent), but no controls, lost the hepatitis B surface antigen. Blinded histologic assessment revealed a significant improvement in periportal necrosis in the treated patients (P = 0.03). CONCLUSIONS: In chronic hepatitis B, treatment with interferon alfa-2b (5 million units per day for 16 weeks) was effective in inducing a sustained loss of viral replication and achieving remission, assessed biochemically and histologically, in over a third of patients. Moreover, in about 10 percent of the patients treated with interferon, hepatitis B surface antigen disappeared from serum.

Adult↗
PubMed1990

The seroepidemiology of human herpesvirus-6 (HHV-6) from a case-control study of leukaemia and lymphoma.

Sera from an epidemiological case-control study of leukaemias and lymphomas conducted between 1980 and 1986 were examined for reactivity to human herpesvirus-6 (HHV-6) by an indirect immunofluorescence assay. Statistical analyses of the data revealed higher HHV-6 seroprevalence and antibody titres in the cases, particularly evident in the disease subtypes acute myeloid leukaemia, Hodgkin's disease (HD), and low-grade non-Hodgkin's lymphoma. Within the control group alone, HHV-6 seroprevalence was placed at 55% at a serum dilution of 1:40. The controls also displayed higher seropositivity in females as compared with males. Further analyses suggest an association of increased HHV-6 seropositivity and geometric mean titre ratio with HD among young adults lacking social contact in the family group. This finding might indicate late exposure to HHV-6 in such persons and could possibly signify late exposure to a number of viruses, including those hypothesized as playing a role in the aetiology of HD. Previous reports have nominated Epstein-Barr virus as a possible candidate. Our results suggest that HHV-6 should be included in further investigations of the aetiology of HD.

Antibodies, Viral↗
PubMed1990

A monoclonal antibody reactive with a 15-kDa cytoplasmic granule-associated protein defines a subpopulation of CD8+ T lymphocytes.

We have recently described a novel method for the production and characterization of mAb reactive with T cell-restricted intracellular antigens. From a panel of antibodies that react specifically with permeabilized T lymphocytes but not with permeabilized B lymphocytes or native T cells, we have selected one, designated TIA-1, that reacts with 20 to 36% of digitonin permeabilized peripheral blood T lymphocytes. Flow cytometric analysis of purified CD4+ and CD8+ subsets showed TIA-1 to recognize a subpopulation of 49 to 64% of CD8+ lymphocytes. Little or no reactivity with CD4+ resting T lymphocytes was observed. TIA-1 did not react with any of a panel of T cell lines, B cell lines, or monocytoid cell lines. TIA-1 reacted strongly with NK cell clones and CD8+ cytolytic T cell clones, and less strongly with CD4+-activated T cell clones, suggesting a preferential expression in cells possessing cytolytic potential. Cell fractionation experiments showed TIA-1 to be membrane associated. Furthermore, Percoll gradient fractionation of a cytolytic T cell clone (T4T8C1) showed the majority of TIA-1 to be contained in a low density membrane fraction that also contained serine protease activity. Immunoelectron microscopy showed TIA-1 to decorate the membranes of electron lucent and electron dense cytoplasmic granules in this same cytolytic T cell clone. Biochemical analysis showed TIA-1 to be a 15-kDa protein in unstimulated T cells. Upon activation with Con A or anti-CD3 antibodies. TIA-1 was induced to form disulfide linked dimers, trimers, and tetramers of the basic 15-kDa unit. Taken together, our data suggest that TIA-1 is a cytolytic granule associated protein that may define a subpopulation of resting CD8+ T lymphocytes possessing cytolytic potential.

Antibodies, Monoclonal↗
PubMed1990

The growth-associated protein GAP-43 appears in dorsal root ganglion cells and in the dorsal horn of the rat spinal cord following peripheral nerve injury.

When adult dorsal root ganglion cells are dissociated and maintained in vitro, both the small dark and the large light neurons show increases in the growth-associated protein GAP-43, a membrane phosphoprotein associated with neuronal development and plasticity. Immunoreactivity for GAP-43 appears in the cytoplasm of the cell bodies as early as 3.5 h post axotomy and is present in neurites and growth cones as soon as they develop. At early stages of culture (4 h to eight days) satellite/Schwann cells are also immunoreactive for GAP-43. Neurons in isolated whole dorsal root ganglion maintained in vitro become GAP-43-immunoreactive between 2 and 3 h after axotomy. It takes three days however, after cutting or crushing the sciatic nerve in adult rats in vivo, for GAP-43 immunoreactivity to appear in the axotomized dorsal root ganglion cells. GAP-43 immunoreactivity can be detected in the central terminals of primary afferent neurons in the superficial laminae of the dorsal horn of the lumbar enlargement four days after sciatic cut or crush. The intensity of the GAP-43 staining reaches a peak at 21 days and becomes undetectable nine weeks following crush injury and 36 weeks following sciatic nerve cut. The pattern of GAP-43 staining is identical to the distribution of sciatic small-calibre afferent terminals. Little or no staining is present in the deep dorsal horn, but GAP-43 does appear in the ipsilateral gracile nucleus 22 days after sciatic injury. In investigating the mechanism of GAP-43 regulation, blockade of axon transport in the sciatic nerve with vinblastine (10(-5) M-10(-4) M) or capsaicin (1.5%) was found to produce a pattern of GAP-43 immunoreactivity in the dorsal horn identical to that found with crush, while electrical stimulation of the sciatic nerve had no effect. Axotomy of primary sensory neurons or the interruption of axon transport in the periphery therefore acts to trigger GAP-43 production in the cell body. The GAP-43 is transported to both the peripheral and the central terminals of the afferents. In the CNS the elevated GAP-43 levels may contribute to an inappropriate synaptic reorganization of afferent terminals that could play a role in the sensory disorders that follow nerve injury.

Animals↗
PubMed1990

The visual field in chronic open angle glaucoma: the rate of change in different regions of the field.

Using automated perimetry the distribution of visual field loss in 40 chronic open angle glaucoma eyes (40 patients) was found to be predominantly in the nasal, supranasal, and superotemporal regions. The rate of change of visual field threshold values in seven regions of the field was measured by trend analysis over 44.9 +/- 17.9 months. Seventeen eyes had a significant rate of field loss in one or more regions of the field with the remaining eyes either showing improvement or stability. Seven of the 17 eyes with significant regional field loss had stable overall fields. The greatest rate of field loss occurred in the temporal and superotemporal regions. The correlation between the mean threshold value of the initial field test and the rate of change of field over time was significant in the temporal region and of borderline significance in the superotemporal region. The relationship was such that the greater the initial threshold value, the greater the subsequent rate of field loss.

Eye↗
PubMed1990

Neodymium: YAG transscleral cyclocoagulation: a clinical study.

Thirty-seven eyes of 35 patients with uncontrolled glaucoma on maximum medication and after previous failed glaucoma surgery, were treated by transscleral cyclocoagulation using the free running mode of the Lasag Microrupter II Neodymium: YAG (Nd:YAG) laser. The indications, technique and results are discussed in this group of complicated glaucomatous eyes and suggests that Nd:YAG laser cyclocoagulation is a safe and effective method of lowering the intraocular pressure (IOP) and improving glaucoma control. The mean pre-treatment IOP was 41 mmHg, and the mean post-operative IOP was 22.5 mmHg. The post-operative IOP was 25 mmHg or less in 27 of 37 eyes (73%) after an average follow-up of eight months.

Adolescent↗
PubMed1990

Fc gamma receptor type III (CD16) is included in the zeta NK receptor complex expressed by human natural killer cells.

We recently reported that CD3- natural killer (NK) cells express the zeta chain of the T-cell receptor complex (zeta NK) in association with higher molecular weight structures whose expression differs between individual NK cell clones. Because NK cell cytolytic activity is known to be triggered by perturbation of the type III Fc gamma receptor (CD16), we sought to determine whether this activating molecule is included in the zeta NK molecular complex. Biochemical evidence for a physical association between CD16 and zeta NK was obtained by comparing immunoprecipitates formed using monoclonal antibodies reactive with each of these molecules by SDS/polyacrylamide gel electrophoresis, immunoblotting, and peptide mapping. In both clonal and polyclonal populations of CD3- NK cells, CD16 and zeta NK specifically associated with one another. Functional evidence for a specific association between CD16 and zeta NK in intact cells was obtained by demonstrating a coordinate down-modulation of both of these molecules induced by either phorbol 12-myristate 13-acetate or monoclonal antibodies reactive with CD16. Our results suggest that Fc gamma receptor type III (CD16) is included in the zeta NK complex and that this complex is likely to play an important role in NK cell activation.

Antibodies, Monoclonal↗
PubMed1990

Chronic myeloid leukaemia in Yorkshire: a case control study.

The results of a case-control study of chronic myeloid leukaemia in adults are reported. 122 cases and 241 controls were interviewed. Excess risks associates with heart disease and related drugs were revealed. In addition a weak association with occupational and/or hobby exposure to irradiation emerged.

Case-Control Studies↗
PubMed1989

Monoclonal antibodies reactive with the T cell receptor zeta chain: production and characterization using a new method.

We have developed a novel method for the production and characterization of monoclonal antibodies reactive with lineage-restricted intracellular Ag. Using this technique, we have produced a panel of antibodies that react specifically with permeabilized T lymphocytes but not with permeabilized B lymphocytes or native T cells. One of these antibodies, designated TIA-2, was found to react with greater than 98% of peripheral blood T lymphocytes. Immunoblotting experiments showed TIA-2 to recognize a 32 kd protein that was reduced to 16 kDa in the presence of 2-mercaptoethanol. Immunoprecipitates analyzed on non-reducing/reducing diagonal polyacrylamide gels showed the homodimeric structure recognized by TIA-2 to be associated with additional structures whose pattern closely resembled that of the T cell receptor complex. When immunoprecipitates formed using antibodies reactive with CD3 epsilon were immunoblotted with TIA-2, the homodimeric TCR zeta chain was specifically recognized. Using TIA-2 as a TCR zeta specific reagent, we show that whole cell expression of this TCR subunit is dramatically reduced following exposure to mAb reactive with CD3. mAb reactive with activating epitopes of CD2 were also capable of down-modulating the expression of TCR zeta, but to a lesser degree. Exposure to Con A or IL-2, on the other hand, did not reduce the whole cell expression of TCR zeta. Given the central importance of TCR zeta in the expression of a functionally competent Ag receptor, its reduced expression in response to certain activating stimuli is likely to play an important role in regulating T cell responsiveness.

Animals↗
PubMed1989

Integrated R2 sequence in mitochondria of fertile B37N maize encodes and expresses a 130 kD polypeptide similar to that encoded by the S2 episome of S-type male sterile plants.

Expression of a 130 kDa protein from open reading frame 1 of the integrated form of the R2 mitochondrial plasmid in normal mitochondria of B37 and other inbred lines is described. The protein appears identical to that synthesized by the closely related S2 episome found in cytoplasmic male sterile maize of the S type. Protein was detected using antisera raised against a beta-galactosidase:ORF1 fusion product containing the most antigenic region of the ORF1 product. Detection of this protein is in contrast to previous reports that mitochondria of normal, male-fertile lines either do not contain this protein, or that there are 11 in-frame stop codons in the reading frame. The integrated R2 of B37N was cloned and this region sequenced, confirming that a continuous open reading frame existed. These results are discussed in relation to the possible role of the S-type episomes in causing cytoplasmic male sterility.

Amino Acid Sequence↗
PubMed1989

Differences in the chemical expression of rat primary afferent neurons which innervate skin, muscle or joint.

The fluorescent dye Fast Blue was injected in anaesthetized rats into either skin, muscle or knee joint of the hindlimb. Following retrograde transport of the dye to lumbar dorsal root ganglia, the cell bodies of primary afferent neurons innervating these different target tissues were identified in ganglion sections by fluorescence microscopy. The sections were processed to demonstrate activity of the enzyme thiamine monophosphatase, or immunoreactivity to calcitonin gene-related peptide, substance P, or somatostatin, in Fast Blue labelled neurons. In all cases immunoreactivity to the antineurofilament antibody RT97 was used to classify dorsal root ganglion cells as being either small dark (RT97 negative, unmyelinated axons) or large light (RT97 positive, myelinated axons). The proportion of small dark cells labelled from each target decreased in the order: skin, muscle, joint. Thiamine monophosphatase and somatostatin were present only in small dark cells, while calcitonin gene-related peptide and substance P were found in both small dark and large light cells. In large light cells of all three targets, more contained calcitonin gene-related peptide than substance P. Among small dark cells, thiamine monophosphatase and somatostatin were found predominantly in skin afferents, while calcitonin gene-related peptide and substance P were more common in muscle and joint afferents. The chemical expression of primary afferents is therefore characteristic of the peripheral target they innervate. This could reflect either a maintained influence of the target on the afferents, or the factors which operate only during development.

Animals↗
PubMed1989

Heterogeneity of the Ro/SSA antigen. Different molecular forms in lymphocytes and red blood cells.

Ro(SSA) is an intracellular ribonucleoprotein against which autoantibodies are found in a portion of patients with Sjögren's syndrome and systemic lupus erythematosus. A form of Ro(SSA) is described in red blood cells that shares a line of identity with purified Ro(SSA) from bovine spleen and human lymphocytes in counterimmunoelectrophoresis, but has different molecular properties. Ro(SSA) from red blood cells exists in association with only two small RNAs as opposed to four in other cell types, as determined by RNA extraction of protein A-assisted immunoprecipitates. In addition to the common 60-kD Ro(SSA) protein, Western blot analysis revealed an additional 52-kD protein in lymphocytes and a 54-kD protein in red blood cells. The 60-kD form of Ro(SSA) in red cells was found to be antigenically distinct from that in the lymphocyte, because sera were identified that bound each exclusively. Finally, a rabbit antibovine Ro(SSA) serum distinguished red cell from lymphocyte Ro(SSA). These results suggest two distinctive populations of Ro(SSA) proteins and distributions of Ro(SSA) RNAs in the lymphocyte and red blood cell.

Animals↗
PubMed1989

Anti-KJ: a new antibody associated with the syndrome of polymyositis and interstitial lung disease.

Antibodies to aminoacyl-tRNA synthetases (anti-Jo-1, anti-PL-7, anti-PL-12) have been found in the serum of some patients with polymyositis (PM). Patients with these antibodies have an unusually high rate of interstitial lung disease (ILD) in association with their PM. Two patients (K.J. and B.T.) with severe ILD and PM were found to have antibodies to a cytoplasmic antigen, but tests to determine whether the antigen was an aminoacyl-tRNA synthetase were negative, including tests of KJ serum for inhibitory effects on the 20 synthetases. KJ immunoprecipitates did not contain tRNA, in contrast to antisynthetase sera. When IgG samples were added to a reticulocyte in vitro translation system at a concentration of 0.3 mg/ml, KJ IgG inhibited globin mRNA translation by 98%, while anti-Jo-1 IgG inhibited 62% and normal IgG had little effect. Thus, both anti-KJ and the antisynthetases are directed at antigens that are involved in translation and protein synthesis, and both are associated with the syndrome of lung disease and PM. This syndrome may be associated with antibodies to translation-related proteins in general, which may have implications for the link of PM and enteroviruses, which are mRNA viruses.

Adult↗