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Biomedical subjects

A Morgan

Publications and source records attributed to A Morgan.

At least 181 records · Page 10Linked to original sources
PubMed1989

Recurrence of duodenal ulcer and Campylobacter pylori infection after eradication.

The role of Campylobacter pylori gastritis in dyspepsia could be clarified more readily if reliable eradication therapy were available. Antibiotic monotherapy and combined therapy with an antibiotic agent plus a bismuth compound have yielded poor long-term results. In this study, bismuth-tetracycline-metronidazole triple therapy has been used to eradicate C. pylori infection in 100 consecutive patients who were suffering from either a duodenal ulcer or non-ulcer dyspepsia. Examination of a follow-up endoscopic biopsy at eight weeks after treatment showed an eradication rate of C. pylori of 94%. Of 64 patients whose biopsy samples were free of C. pylori infection at eight weeks and who were available for reassessment, 60 (94%) patients had samples that remained free of C. pylori infection on examination of a repeat endoscopic biopsy at 12-37 months (mean, 19.3 months). It is concluded that "triple chemotherapy" can achieve long-term eradication of C. pylori infection effectively in the majority of treated patients and that the recurrence of duodenal ulcers thus may be diminished.

Administration, Oral↗
PubMed1989

Low molecular mass GTP-binding proteins of adrenal chromaffin cells are present on the secretory granule.

Adrenal medullary homogenates and chromaffin granule membranes were separated by SDS-polyacrylamide gel electrophoresis and GTP-binding proteins detected using [alpha-32P]GTP binding to nitrocellulose blots. Four GTP-binding polypeptides of 24, 22, 20 and 18 kDa were routinely found in medullary homogenates and all were also found in isolated chromaffin granule membranes. The GTP-binding polypeptides co-sedimented with granule membrane markers following separation on sucrose gradients. On the basis of trypsin sensitivity and resistance to extraction, the GTP-binding proteins appeared to be tightly bound to the cytoplasmic surface of the granules. One or more of the secretory granule GTP-binding proteins could be involved in exocytosis in adrenal chromaffin cells.

Adrenal Medulla↗
PubMed1989

The control of cytoskeletal actin and exocytosis in intact and permeabilized adrenal chromaffin cells: role of calcium and protein kinase C.

The control of cytoskeletal actin and exocytosis was examined in intact and digitonin-permeabilized chromaffin cells. Cytoskeletal actin was assayed by determining the actin content of Triton-insoluble cytoskeletons. The secretagogues nicotine, high K+ and Ba2+ resulted in a rapid reduction in the amount of actin associated with the cytoskeleton. The effect of nicotine but not high K+ on cytoskeletal actin was independent of external Ca2+ and the reduction in cytoskeletal actin was mimicked by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate suggesting a role for protein kinase C. In digitonin-permeabilized cells micromolar calcium produced both catecholamine secretion and a reduction in cytoskeletal actin. The reduction in cytoskeletal actin was transient. Secretion was enhanced by the GTP analogue guanosine 5'-(3-O-thio)triphosphate and the analogue also reduced cytoskeletal actin at low calcium levels. The effects of guanosine 5'-(3-O-thio)triphosphate were inhibited by the phospholipase C inhibitor neomycin and were mimicked by 12-O-tetradecanoylphorbol-13-acetate. An additional GTP analogue, guanyl-5'-yl imidodiphosphate, had no effect on cytoskeletal actin. These results provide further evidence for a requirement for reorganisation of cortical actin in the secretory processes and suggest that the reduction in actin associated with the cytoskeleton may be mediated by protein kinase C and/or calcium in intact and permeabilized chromaffin cells.

Actins↗
PubMed1989

A multiple regression analysis for accurate background subtraction in 99Tcm-DTPA renography.

A technique for accurate background subtraction in 99Tcm-DTPA renography is described. The technique is based on a multiple regression analysis of the renal curves and separate heart and soft tissue curves which together represent background activity. It is compared, in over 100 renograms, with a previously described linear regression technique. Results show that the method provides accurate background subtraction, even in very poorly functioning kidneys, thus enabling relative renal filtration and excretion to be accurately estimated.

Humans↗
PubMed1989

Expression of Epstein-Barr virus membrane antigen gp340/220 in mouse fibroblasts using a bovine papillomavirus vector.

Epstein-Barr virus (EBV) membrane antigen glycoproteins gp340 and gp220 are encoded by a single gene. We have inserted this gene into a bovine papillomavirus (BPV) vector and expressed gp340/220 in mammalian cells under the control of the mouse metallothionein promoter. The proteins produced were of similar Mr, showed similar antigenic specificity and were transported to the same subcellular location as the authentic gp340/220. The inclusion of heavy metal ions in the medium had no effect on the levels of gp340/220, which were approximately the same as those found in standard EBV-transformed lymphoblastoid cell lines, e.g. B95-8. Cells that expressed gp340/220 were selected by several rounds of fluorescence-activated cell sorting, but on passage they rapidly lost the ability to express this glycoprotein. In contrast to this we found that BPV-transformed cells expressing a truncated version of gp340/220 still produced it at significant levels after extended passage.

Animals↗
PubMed1989

Effect of inhaled alpha-emitting nuclides on mouse alveolar macrophages.

The effects of inhaled alpha emitters on the free cell population of the mouse lung were investigated up to 100 days after exposure. Groups of mice inhaled aerosols of 238PuO2, 239PuO2, or 241Am(NO3)3 to give alveolar deposits resulting in lung-averaged cumulative absorbed doses of about 20 Gy by the end of the study. Initially, with 238Pu most of the activity was associated with relatively few pulmonary alveolar macrophages (PAM), whereas with 241Am, all pulmonary alveolar macrophages were labeled and a substantial fraction was extracellular. The free cell population of the lung was sampled using bronchoalveolar lavage. The main parameters investigated were (a) the recovery and total numbers of free cells, including PAM, lymphocytes, and neutrophils; (b) the incidence of nuclear abnormalities in PAM (cells with more than one nucleus or with micronuclei); and (c) metabolic activation of PAM from measurements of their size and associated beta-glucuronidase activity. All three actinides produced depletions in total numbers of PAM, increased incidences of nuclear abnormalities, and metabolic activation of PAM, without a marked infiltration of inflammatory cells. Americium-241, which is distributed relatively uniformly in PAM, produced the most marked changes in that population and 238Pu, which gave the most inhomogeneous distribution of activity, produced the least.

Administration, Inhalation↗
PubMed1989

Impaired mitogen responses of the non-leukaemic B cells from patients with chronic lymphocytic leukaemia.

We investigated the immunological mechanism of the low level of circulating immunoglobulin and depressed primary and secondary responses of patients with chronic lymphocytic leukaemia (B-CLL) using purified non-leukaemic B cells in vitro. To assess the function of the non-leukaemic B cells we separated them from the much larger leukaemic population, which expresses the pan-T cell marker CD5, by immunoabsorption using anti-CD5 antibodies and Dynabeads. Immunoglobulin production was measured after the cells had been cultured with the B cell mitogens, pokeweed mitogen (PWM) and Staphylococcus aureus Cowan strain 1 (SAC). Autologous T cells that were found to function normally in our systems were added to cultures containing PWM. Non-leukaemic B cells from 15 B-CLL patients produced 539 ng/ml, immunoglobulin (mean value) with SAC and 162 ng/ml with PWM compared with 14,182 and 5513 ng/ml, respectively, from B cells from normal, age-matched control patients. Most of the immunoglobulin produced in the non-leukaemic B cell cultures carried the light chain associated with the leukaemic clone. We conclude that even at early stages in the disease (12 patients were Rai stage 0 patients) when the total serum immunoglobulin levels are still near normal, the B cells respond poorly to B cell mitogens.

B-Lymphocytes↗
PubMed1988

A major role for protein kinase C in calcium-activated exocytosis in permeabilised adrenal chromaffin cells.

The role of endogenously activated protein kinase C in calcium-activated exocytosis was examined in digitonin-permeabilised bovine adrenal chromaffin cells. Protein kinase C activity was reduced by down-regulation following long-term treatment with PMA or by using the inhibitor sphingosine. Both treatments resulted in a substantial reduction in catecholamine secretion elicited by micromolar calcium, indicating that endogenous activation of protein kinase C is a major requirement for calcium-activated exocytosis in chromaffin cells.

Adrenal Medulla↗
PubMed1988

In vitro T cell responses to a candidate Epstein-Barr virus vaccine: human CD4+ T cell clones specific for the major envelope glycoprotein gp340.

Specific T cell proliferation was observed in short-term blood mononuclear cell cultures set up from Epstein-Barr virus (EBV)-immune individuals and challenged either with UV-irradiated EB virions or with a candidate subunit vaccine preparation, the purified envelope glycoprotein gp340 incorporated into immune stimulating complexes (gp340 iscoms). Limiting dilution culture of the activated T lymphoblasts in interleukin 2-containing medium generated stable CD3+CD4+CD8- T cell clones. Particular clones showing virus-specific proliferation in preliminary screening assays were selected for more detailed study. Three gp340 iscoms-induced clones from EBV-immune donor CG responded specifically to restimulation either with UV-EBV or with purified gp340 iscoms in the presence of autologous antigen-presenting cells (APC). Both T cell-depleted blood mononuclear cells and the EBV-transformed B cell line (treated with Acyclovir to block endogenous gp340 production) could be used for presentation, the latter being the more efficient when gp340 iscoms was the source of antigen. Blocking studies with monoclonal antibodies to HLA class II antigens and experiments using HLA-typed allogeneic APC indicated that all three gp340-specific CG clones were restricted through the HLA-DR2 antigen. One gp340 iscoms-induced clone from another EBV-immune donor, MR, likewise showed gp340-specific proliferation, in this case restricted through a HLA-DR4 antigen. Using HLA-DR-homozygous B cell lines representing the five known DR4 subtypes, efficient presentation of gp340 to this T cell clone was observed with both DR4 Dw4 and DR4 Dw14 antigens. Parallel experiments on one UV-EBV-induced T cell clone from donor MR gave a different pattern of results; these cells appeared to be specific for a virus structural component other than gp340 and to be restricted through an HLA-DP determinant.

Antibodies, Viral↗
PubMed1988

12-Lipoxygenase activity in human uterine cervix.

Homogenates prepared from sections of human uterine cervix or endometrium were incubated with [1-14C]arachidonate and the products examined by radio-TLC. A major product chromatographing with 12-hydroxyeicosatetraenoic acid (12-HETE), and a number of more polar metabolites which were unaffected by 50 microM indomethacin but decreased to the same extent as 12-HETE by 50 microM nordihydroguaiaretic acid, were demonstrated by this technique. The addition of glutathione to the incubation mixture increased the production of 12-HETE, with a proportional decrease in the polar products. There was a large variation in 12-lipoxygenase activity measured in different cervix samples. The levels of the enzyme in the cervix were similar in two groups of uterine samples classified by the histological appearance of the endometrium as proliferative and secretory. However activity was significantly lower in samples taken from post-menopausal patients compared with pre-menopausal patients.

Arachidonate 12-Lipoxygenase↗
PubMed1988

The effect of firing temperature on the lung retention and translocation of Pu following the inhalation of 238PuO2 and 239PuO2 by CBA/H mice.

Mice were exposed by inhalation to sized aerosols of 238PuO2 and 239PuO2 which had been fired at temperatures from 550-1250 degrees C and groups killed at times between 1 d and 2 y after exposure. Measurements were made of 238Pu and 239Pu in the lungs, lung-associated lymph nodes, liver and skeleton. With 239Pu, lung retention and translocation were independent of firing temperature. With 238Pu on the other hand, the retention in lung was greater initially than for 239Pu but, with the low-fired oxide, eventually fell below that of 239Pu. With high-fired oxides, the lung retention of 238Pu still exceeded that of 239Pu after 2 y. Translocation to liver and bone was invariably greater for 238Pu than for 239Pu and was also dependent on firing temperature. The practical implications of these findings are discussed.

Administration, Inhalation↗
PubMed1988

Pharmacotherapy for aphasia.

Selected features of aphasia may reflect disruption of specific neurotransmitter systems. Pharmacotherapy focused on these aphasic symptoms may improve language performance following stroke. We attempted to restore speech fluency in a patient with long-standing transcortical motor aphasia by treating his symptoms of hesitancy and impaired initiation of speech with bromocriptine. During therapy his language performance improved substantially, due to reduced latency of response, decreased paraphasias, and increased naming ability. After cessation of drug therapy his language returned to baseline.

Aphasia↗
PubMed1987

Sequential appearance of cytoskeletal components during the early stages of neurite outgrowth from cerebellar granule cells in vitro.

Cerebellar granule cells derived from one-week-old rat pups have been placed into culture to examine the expression of microfilament, microtubular and neurofilament proteins in developing neurites up to 2 days in vitro. Immunofluorescence and rhodamine-phalloidin studies have shown that the first cytoskeletal element to appear in the developing neurite was the microfilament network which was present in cell processes and expansions from at least 8 minutes in vitro. Rhodamine-phalloidin fluorescence was maintained in the developing neurite over 2 days and was enriched in some growth cones. At between 30 and 60 min in culture microtubules (reacting with anti alpha-tubulin antibodies) appeared in the neurites but did not ramify throughout the growth cone at this or later time points. The expression of tyrosylated alpha-tubulin in microtubules of the developing neurite appeared to precede that of acetylated alpha-tubulin. Only one of the neurofilament subunits, the 200 kDa subunit, could be positively identified in granule cell processes in these cultures. The developmental pattern of cytoskeletal protein expression in granule cell neurites in vitro may reflect a process of stabilisation of the growing neurite behind an active, motile growth cone.

Animals↗
PubMed1987

Rapid chloroplast segregation and recombination of mitochondrial DNA in Brassica cybrids.

Brassica cybrids were obtained after fusing protoplasts of fertile and cytoplasmic male sterile (CMS) B. napus lines carrying the original B. napus, and the Ogura Raphanus sativus cytoplasms, respectively. Iodoacetate treatment of the fertile line and X-irradiation of the CMS line prevented colony formation from the parental protoplasts. Colony formation, however, was obtained after protoplast fusion. Hybrid cytoplasm formation was studied in 0.5 g to 5.0 calli grown from a fused protoplast after an estimated 19 to 22 cell divisions. Chloroplasts and mitochondria were identified in the calli by hybridizing appropriate DNA probes to total cellular DNA. Out of the 42 clones studied 37 were confirmed as cybrids. Chloroplasts in all of the cybrid clones were found to derive from the fertile parent. Mitochondrial DNA (mtDNA) segregation was complete in some but not all of the clones. In the cybrids, mtDNA was different from the parental plants. Physical mapping revealed recombination in a region which is not normally involved in the formation of subgenomic mtDNA circles. The role of treatments used to facilitate the recovery of cybrids, and of organelle compatibility in hybrid cytoplasm formation is discussed.

Brassica napus↗