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Biomedical subjects

A Martin

Publications and source records attributed to A Martin.

At least 631 records · Page 35Linked to original sources
PubMed1988

Age-related changes in the translocation of phosphatidate phosphohydrolase from the cytosol to microsomal membranes in rat liver.

The effects of oleate, spermine and chlorpromazine were assayed in the presence or absence of 0.15 M KCl on the translocation of phosphatidate phosphohydrolase activity from cytosol to endoplasmic reticulum membranes in liver homogenates obtained from rats aged 1, 30, 60, 180 and 360 days. Marked age-associated decreases in phosphatidate phosphohydrolase distribution onto the membranes were demonstrated under nearly all conditions. In liver homogenates taken from 1-day-old rats and incubated with 0.15 M KCl, most of the enzyme was active (associated with the membranes). Physiological salt concentration (0.15 M KCl) produced a 2-fold increase of oleate-induced translocation of phosphatidate phosphohydrolase activity in liver homogenates from 1-day-old rats; it had no effect on those from 60-day-old rats, and produced a notable decline in liver homogenates obtained from 180- and 360-day-old rats. The promoting effect of spermine on oleate-induced translocation of this enzyme activity was higher in younger rats when incubated in the absence of 0.15 M KCl. Chlorpromazine did not show its usual antagonizing effect on oleate-induced translocation of phosphatidate phosphohydrolase when added to homogenates taken from 1-day-old rats. The antagonizing effect was slightly apparent in liver homogenates from 30-day-old rats and was more pronounced in those from 60-day-old rats in which the values diminished to one-half and to one-third either in the presence or absence of 0.15 M KCl.

Aging↗
PubMed1988

Hormonal regulation of phosphatidylcholine synthesis by reversible modulation of cytidylyltransferase.

The effect of both lipolytic and antilipolytic hormones on the turnover of phosphatidylcholine in freshly isolated rat adipocytes was investigated. Treatment of adipocytes with agonists such as glucagon or isoprenaline that stimulate lipolysis through a cyclic AMP-dependent mechanism caused an increase in the incorporation of [Me-3H]choline into phosphatidylcholine. Pulse-chase studies indicated that the stimulation was due to an increase in the conversion of choline into phosphatidylcholine, which was both time- and dose-dependent. The stimulatory effect of isoprenaline was inhibited in a dose-dependent manner by oxytocin or insulin. Oxytocin inhibited the incorporation of [Me-3H]choline into phosphatidylcholine in both the presence and the absence of isoprenaline, whereas in the absence of isoprenaline insulin increased the incorporation of [Me-3H]choline into phosphatidylcholine. The effects of isoprenaline, oxytocin and insulin on the incorporation of [3H]choline into phosphatidylcholine were paralleled by changes in the activity of CTP:phosphocholine cytidylyltransferase.

Adipose Tissue↗
PubMed1988

Monoclonal antibodies against mesothelial membrane antigen discriminate between malignant mesothelioma and lung adenocarcinoma.

Monoclonal antibodies (MAbs) were generated by immunizing mice with the mesothelioma cell line SPC111 and selected by indirect immunofluorescence on viable cells. Indirect immunofluorescence staining and radioimmunoassays demonstrated selective binding of the antibodies ME1 and ME2 with the surface membrane of mesothelioma, but not with lung adenocarcinoma cell lines. Lung small-cell carcinoma cell lines were unreactive, while staining was seen in a proportion of lung squamous-cell carcinoma cell lines. The antibodies were unreactive with other cell lines, including breast, colon, ovarian, and renal-cell carcinoma, leukemia, and lung fibroblast. The antibodies stained normal mesothelial cells, but were unreactive with normal bronchial epithelial cells in primary cultures, or peripheral blood cells. Immunohistochemical staining of cryostat sections of tumor tissues confirmed the ability of the antibodies to distinguish between mesothelioma and lung adenocarcinoma. All 12 mesothelioma tissues, but none of 9 lung adenocarcinomas or large-cell carcinomas, stained with the MAbs. Staining of malignant mesothelioma tissues was very homogeneous. Some lung squamous-cell carcinomas and breast carcinomas were stained focally by both, and some ovarian carcinomas by one antibody. Solid-phase radioimmunoassays demonstrated antigen sensitivity to chymotrypsin digestion and binding competition between the antibodies. The antibodies ME1 and ME2 identify a surface membrane antigen with preferential expression on normal and malignant mesothelial cells. They distinguish malignant mesothelioma from lung adenocarcinoma on cryostat sections and promise to be useful tools in biological studies of mesothelial cells.

Adenocarcinoma↗
PubMed1988

Engineering a poliovirus type 2 antigenic site on a type 1 capsid results in a chimaeric virus which is neurovirulent for mice.

Poliovirus type 2 (PV-2) Lansing strain produces a fatal paralytic disease in mice after intracerebral injection, whereas poliovirus type 1 (PV-1) Mahoney strain causes disease only in primates. Atomic models derived from the three-dimensional crystal structure of the PV-1 Mahoney strain have been used to locate three antigenic sites on the surface of the virion. We report here the construction of type 1-type 2 chimaeric polioviruses in which antigenic site 1 from the PV-1 Mahoney strain was substituted by that of the PV-2 Lansing strain by nucleotide cassette exchange in a cloned PV-1 cDNA molecule. These chimaeras proved to have mosaic capsids with composite type 1 and type 2 antigenicity, and induced a neutralizing response against both PV-1 and PV-2 when injected into rabbits. Moreover, a six-amino-acid change in PV-1 antigenic site 1 was shown to be responsible for a remarkable host-range mutation in so far as one of the two type 1-type 2 chimaera was highly neurovirulent for mice.

Animals↗
PubMed1988

Scintigraphic detection in mice of inflammatory lesions and tumours by an indium-labelled monoclonal antibody directed against Mac-1 antigen.

The monoclonal antibody, 3A33, directed against Mac-1 antigen which is expressed essentially on macrophages and polymorphonuclear cells, was injected i.v. into mice, as part of an attempt to visualize inflammatory lesions and tumours by external scintigraphy. The monoclonal antibody, a rat IgG2a, was conjugated with a bifunctional chelating agent, diethylenetriaminepentaacetic acid at a 1:1 molecular ratio and complexed with 111-indium, a procedure which apparently did not alter its binding to peritoneal macrophages and provided relatively stable cell labelling. An unrelated rat IgG2a of unknown specificity radiolabelled in the same manner as 3A33 served as a control. The uptake of i.v. injected 3A33 by peritoneal macrophages was up to 50 times that of unrelated IgG2a. After i.v. inoculation, the antibody accumulated in the liver, spleen, lung, in foot-pad inflammatory reactions induced by injection of Freund's adjuvant and in experimentally grafted tumours. The 3A33: non-specific IgG2a uptake ratio in inflammatory lesions and tumours, however, was much lower than for peritoneal macrophages and was generally close to 2. This was sufficient to obtain scintigraphic images of inflammations and tumours. The images obtained after injection of 3A33 were clearly of better quality than those given by the non-specific immunoglobulin. They could be improved by subtraction of the vascular images obtained after injection of 99m-technetium serum albumin. The labelling of Mac-1-positive blood mononuclear cells by in vitro incubation with radioactive 3A33 was not intense enough to allow scintigraphic imaging after in vivo re-infusion but seemed more selective than the injection of whole antibody in detecting inflammatory reactions. These results seem interesting in view of the potential human application to the detection inflammatory lesions and the appreciation of tumour inflammatory components. Possible improvements in the technique are discussed.

Animals↗
PubMed1988

Structure and motility of primary cilia in the follicular epithelium of the human thyroid.

In order to clarify contradictory reports concerning ciliary structure and function, follicular epithelium from macroscopically normal portions of 37 surgical specimens of human thyroid were processed for video-microscopy and/or transmission electron microscopy. The cilia of living cells were immotile. In transverse sections the cilia revealed a 9 + 0 pattern at the base of the shaft, whereas towards the distal end the number of microtubular doublets diminished. Dynein arms, radial spokes and central microtubules were absent. The immotility and structure of these primary cilia implies that their function is not related to motility. The phylogenetic and ontogenetic development of the thyroid suggests that tumor cells of follicular origin displaying abnormal secondary cilia may represent a pathological variant of differentiation.

Adenocarcinoma↗
PubMed1988

Cerebral ischaemia reduces the density of 5-HT2 binding sites in the frontal cortex of the gerbil.

The 5-HT2 antagonist [3H]ketanserin labels a single population of high affinity sites (Kd 0.48 +/- 0.03 nM; Bmax 206 +/- 20 fmol/mg protein) in the frontal cortex of the gerbil. Specific binding of [3H]ketanserin was displaced by a number of 5-HT2A antagonists ritanserin, cyproheptadine and methysergide) but not by the 5-HT1A agonist, 8-hydroxy-2-(di-n- propylamino)tetralin (8-OH-DPAT) or the 5-HT1A/1B agonists 5-carboxyamidotryptamine (5-CT) or RU 24969, indicating that the labelled site probably represents the 5-HT2 receptor. Cerebral ischaemia induced in either a 3 hr unilateral non-recovery model or a 5 min bilateral, 3-day recovery model, resulted in a significant decrease in the density of 5-HT2 binding sites in the ischaemic frontal cortex without an apparent change in their affinity for the ligand. The decrease in density was not simply related to levels of 5-HT because occlusion of the right carotid artery for 3 hr resulted in bilateral depletion of 5-HT but only in an ipsilateral reduction in the density of binding sites. In addition, a significant decrease in the density of 5-HT2 binding sites occurred in the recovery model at a time when the levels of 5-HT in the cortex were unaltered.

Animals↗
PubMed1988

Thiouracil and antibody titers of chickens from lines divergently selected for antibody response to sheep erythrocytes.

Chickens from lines selected for high (HA) and low (LA) antibody response to sheep red blood cells (SRBC) were fed ad libitum either a diet containing 0 (control) or .1% thiouracil (TF) throughout two trials. Chicks were injected intravenously with .1 ml of .25% SRBC at 37 days of age in Trial 1, and a booster of the same dosage was given to half of these chicks at 61 days of age. Antibody titers were measured 5 and 3 days after primary and secondary inoculations. In Trial 2, primary inoculations of SRBC were given at 21 and 38 days of age, and chicks were bled 3, 5, 7 and 10 days after inoculation. TF chicks had lower body weights and higher feed efficiencies than controls. Plasma thyroxine (T4) concentrations were similar for both lines, but line by diet interactions were present for plasma triiodothyronine (T3) and T3/T4 ratios. When fed the control diet, T3 concentrations and T3/T4 ratios were higher for line HA than line LA, but the pattern was reversed when thiouracil was fed. Antibody titers to SRBC in both trials were higher for HA than LA chicks, but were similar for TF and control chicks. Persistence of elevated titers appeared to be greater in TF than control chicks. There were no differences between TF and control chicks for heterohphil/lymphocyte ratios.

Animals↗
PubMed1988

Production of monoclonal human antibody to HLA-DR5 (DRw11) by mouse/human heterohybridomas.

We describe here the production of a human monoclonal antibody to the HLA-DR5 antigen. A human B-cell line secreting cytotoxic antibody that reacted preferentially with DR5-positive targets was fused to the mouse myeloma P3X63Ag8.653 and the resulting heterohybridomas cloned twice. The clones secreted human IgM (lambda light chain), which showed specificity for the DR5 antigen in cytotoxicity assays and reacted with DRw11-positive but not DRw12-positive targets. These results demonstrate the potential of this approach to the production of human monoclonal antibodies to transplantation antigens.

Animals↗
PubMed1988

Retention of cyclic AMP response to TSH in a cloned human thyrocyte/T cell hybridoma (HY2-15).

Our observation of a human T cell leukemia cell (Molt 4) demonstrating low affinity thyroid-stimulating hormone (TSH) responses, as evidenced by generation of cyclic AMP, led us to test Molt 4 cells as a suitable partner for immortalizing high affinity TSH receptors present on human thyroid cells. Therefore, we generated a hybridoma (HY2-15) by a fusion between thyroid monolayer cells from a patient with Graves' disease, and a hypoxanthine-aminopterin-thymidine (HAT)-sensitive variant of this human T cell leukemia line, Molt 4-8AGR. The hybrid nature of HY2-15 was confirmed by DNA histograms using propidium iodide and flow cytometry. Karyotyping showed the HY2-15 cells to have five sets of chromosomes and human leukocyte antigen (HLA) class I determination revealed the presence of an additional HLA class I antigen (A2) not present on the Molt 4 partner cells. The established, cloned, hybridoma cells showed a greater than 30-fold increase in cyclic AMP release after stimulation with bovine TSH (bTSH, 1 mU/ml) with a minimum detectable stimulating dose of less than 10 microU/ml bTSH. However, no other thyroid-specific functions could be detected. Furthermore, HY2-15 cells failed to express HLA class II antigens either constitutively or in response to recombinant human gamma interferon (IF) and a variety of other stimuli, data similar to the Molt 4 partner cells but in contrast to human thyroid cells which show high sensitivity to gamma IF. The preservation of highly sensitive TSH responsiveness in a proliferating cell offers a unique approach to the study of human TSH receptor function.

Cell Division↗
PubMed1988

[Comparative study of sodium valproate and ketoprofen in the treatment of postoperative pain].

Experimental data has shown that sodium valproate has analgesic properties in animals, probably by way of the increase in cerebral and spinal gamma amino-butyric acid (GABA) it induces. A study was therefore designed to assess this analgesia in man in the postoperative period. A first open study was carried out on 12 consenting patients, who were each given 15 mg.kg-1 sodium valproate intravenously over 20 min. A significant decrease in pain intensity, measured by an analogic visual scale, was seen from the 20th min up to the 140th min. A controlled double-blind study was then carried out; it included three groups of 13 patients each. Patients in group 1 were given placebo (5% dextrose); group 2 patients were given 15 mg.kg-1 sodium valproate intravenously over 20 min, and group 3 patients 2 mg.kg-1 ketoprofen intravenously over 20 min also. There was no difference in the pain intensity profile of groups 1 and 2: sodium valproate was no more efficient than placebo in relieving postoperative pain. However, ketoprofen gave a prompt and effective analgesic effect. The clinical data obtained with sodium valproate in man during the postoperative period stand in contrast with the promising animal results. Sodium valproate cannot be recommended for the treatment of postoperative pain.

Adult↗
PubMed1988

Human autoimmune thyroid disease: cellular and molecular aspects.

We have reviewed the impact of cellular and molecular biology on our understanding of the immune system and thyroid autoimmune disease and presented the evidence that MHC, TCR and immunoglobulin genes are involved in susceptibility to such disease. At the level of the target thyroid epithelial cell, the identification of the genes for Tg and TPO (the microsomal antigen) using recombinant DNA techniques are evidence of dramatic progress. On the humoral side of the immune response, the investigation of restricted clonality is still hampered by the technical difficulties in obtaining immortal B cell lines producing thyroid antigen specific high affinity IgG antibodies, although the advent of tools to sequence the immunoglobulin V genes from small quantities of DNA will overcome this difficulty (e.g. by polymerase chain reactions). T cells have also begun to be characterized both phenotypically, thanks to the advent of ever better characterized monoclonal antibodies, and functionally at the clonal level, thanks to refinement of cell culture techniques. Future studies in this area will also need to focus on cell immortalization and maintenance of antigen-specific responses although, major strides in the direct sequencing of the TCR are taking place and investigation of T cell receptors in antigen-specific T cells should be feasible. MHC associations with thyroid autoimmune disease, as studied by analysis of RFLP patterns, have not significantly improved already established serological HLA associations and direct MHC gene sequencing will be required. Analysis of the organ-specific regulation of MHC class II gene expression has led to a better understanding of the functional role of MHC class II genes in thyroid autoimmune disease at the target cell level. Such studies have pointed out important local immune responses within the thyroid gland but have not yet provided the initiating factor or factors for human autoimmune thyroid disease in genetically susceptible individuals.

Antigens↗
PubMed1988

Noncardiac side-effects of long-term oral amiodarone in the elderly.

Amiodarone is a powerful anti-arrhythmic drug. However, its use is somewhat limited by side-effects. No study examining side-effects specifically in elderly patients exists. We have reviewed noncardiac side-effects in 61 elderly patients on long-term oral amiodarone treatment (follow-up 3-66 months). The most troublesome side-effect was hypothyroidism (nine patients, 15%). No cases of frank hyperthyroidism were seen. Elevation of aspartate transaminase (AST) was common (16 patients, 26%), but generally mild and transient. Photosensitivity occurred in six patients (10%). Corneal deposits were common but gave rise to symptoms in only one patient. Two patients reported tremor. Hypothyroidism appeared to be more common and photosensitivity less common than in previously reported series in younger adults. Possible reasons for this are discussed. It is our policy to continue to prescribe amiodarone to elderly patients, regulate monitoring for adverse effects is however mandatory.

Administration, Oral↗