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Biomedical subjects

J Trotter

Publications and source records attributed to J Trotter.

At least 91 records · Page 5Linked to original sources
PubMed1984

Homing of Lyt-2+ and Lyt-2- T cell subsets and B lymphocytes to the central nervous system of mice with acute experimental allergic encephalomyelitis.

Subpopulations of lymphoid cells were compared with respect to their ability to migrate into the central nervous system (CNS) of mice with acute experimental allergic encephalomyelitis (EAE). In mice with established lesions, the majority of cells homing to the CNS are not presensitized to CNS antigens. B cells had a much reduced capacity to migrate into the CNS of sick mice compared with T cells. However, T cells of both the Lyt-2+ and Lyt-2- subsets homed equally well to the CNS. The relative paucity of B cells in the lesions of EAE and multiple sclerosis may thus partly result from the limited ability of these cells to migrate into the CNS across the blood-brain endothelial barrier. The predominance of Lyt-2- T cells over Lyt-2+ cells in these CNS lesions is unlikely to result from such a difference in homing capacity, but may reflect the ratio of these two cell types in the blood or preferential in situ expansion of the Lyt-2- population.

Animals↗
PubMed1983

Flow cytometric separation of gonadotrophs from dispersed rat pituitaries using a fluorescent GnRH antagonist.

A gonadotropin-releasing hormone (GnRH) antagonist, [Ac-delta 3 Pro1,pFDPhe2,DTrp3,DLys6[-GnRH, was synthesized, conjugated to tetramethyl rhodamine, and found to retain GnRH antagonist activity. The fluorescent compound was used to label dispersed pituitary cells from 14-17 day-old Sprague-Dawley female rats. A subset comprising approximately 10% of the pituitary population was specifically labeled with a mean intensity of fluorescence 4.9-fold higher than the unlabeled population. The labeled cells were larger on average than the general population as inferred by forward narrow angle light scatter intensity measurements, and more granular as inferred by right angle light scatter intensity. Cells were sorted on the basis of fluorescent intensity: gonadotrophs were found to be concentrated in the rhodamine-positive fraction 5- or 6-fold relative to unfractionated cells, and 21- or 28-fold relative to rhodamine-negative fraction cells based on LH or FSH content, respectively. Gonadotrophs comprised 73 +/- 3.9% of the rhodamine-positive fraction by immunocytochemical staining. Sorted rhodamine-positive cells were cultured and found to be fully functional with respect to subsequent challenge with 30 nM GnRH. We conclude that the use of the fluorescent GnRH antagonist in conjunction with a multi-parameter cell sorter allows the purification of gonadotrophs, indicating, as expected, that these cells have a significantly higher level of GnRH binding sites than the general pituitary population. This technology should prove generally valuable in endocrine research.

Animals↗
PubMed1983

X-ray structural studies and molecular orbital calculations (CNDO/2) in a series of cyclopenta[a]phenanthrenes: attempts at correlation with carcinogenicity.

Comparative X-ray crystallographic structure analyses have been carried out on seven cyclopenta[a]phenanthrenes, namely 15,16-dihydocyclopenta[a]phenanthren-17-one and its 2-, 6- and 12-methyl homologues (non-carcinogens) and the 7-and 11-methyl and 1,11-methano derivatives (carcinogens). All-valence-electron molecular-orbital calculations by the CNDO/2 method, using the crystallographic parameters, have also been executed. Charge distribution and the energies of the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) have been calculated. With one exception all the molecules show only small deviations from planarity, the exception being the strongly carcinogenic 11-methyl-17-ketone in which the bay-region methyl group causes out-of-plane deformation of the benzo rings of 12.5 degrees. Among the other six compounds the two carcinogens are readily differentiated by high angle strain induced by a 7-methyl group or a 1,11-methano bridge. As expected, the HOMO's of these molecules to some extent reflect their ease of chemical oxidation at the 6,7-double bond; biological oxidation is less easy to correlate probably due to spatial restrictions at the active site within the mono-oxygenase.

Carcinogens↗
PubMed1982

Acyltransferase-catalyzed cleavage of arachidonic acid from phospholipids and transfer to lysophosphatides in lymphocytes and macrophages.

The cleavage of fatty acyl moieties from phospholipids was compared in intact cells and homogenates of mouse lymphocytes (thymocytes, spleen cells) and macrophages. Liberation of free arachidonic acid during incubations of intact cells was only detectable in the presence of albumin. Homogenization of prelabeled thymocytes and further incubation of these homogenates at 37 degrees C resulted in a pronounced decrease of phospholipid degradation and cleavage of arachidonoyl residues, while further incubation of homogenates from prelabeled macrophages produced a greatly increased phospholipid degradation. Homogenates of macrophages but not those of thymocytes contain substantial activities of phospholipase A2 detectable using exogenous radiolabeled substrates. These findings indicate that in thymocytes cleavage of arachidonic acid from phosphatidylcholine is an active process that is not catalyzed by phospholipase A2. Addition of CoA and lysophosphatidylethanolamine to prelabeled thymocyte homogenates induced a fast breakdown of phosphatidylcholine and transfer of arachidonic acid to phosphatidylethanolamine, as in seen during incubations of intact thymocytes or macrophages. The transfer is restricted to arachidonic acid and does not require addition of ATP. Sodium cholate, a known inhibitor of the acyl-CoA:lysophosphatide acyltransferase, completely inhibited this transfer reaction. These results suggest that the CoA-mediated, ATP-independent breakdown of phosphatidylcholine and transfer of arachidonic acid is catalyzed by the acyl-CoA:lysophosphatide acyltransferase operating in reverse.

Acyltransferases↗
PubMed1982

Biochemical characterization and cellular distribution of a polymorphic, murine cell-surface glycoprotein expressed on lymphoid tissues.

A murine leukocyte surface glycoprotein (Mr = 95 000) has been defined by means of xenogeneic monoclonal antibodies. In normal hematopoietic tissues, the glycoprotein is found in highest amounts in the bone marrow. Flow cytometric analysis shows that essentially all bone-marrow cells express the glycoprotein and that it is a major component of a subpopulation of cells containing predominantly granulocytic precursors. In contrast, only about 5 percent of thymocytes express sufficient glycoprotein to be detected by flow cytometric analysis, although under stringent conditions up to 20 percent of thymocytes are susceptible to complement-mediated cytotoxicity using a monoclonal antibody against the glycoprotein. Functional assays showed that both prothymocytes and colony forming unit-spleen express the glycoprotein which is broadly distributed on murine hematopoietic tumor cell lines. However, although some Thy-1+ (T) cell lymphomas express large amounts of the glycoprotein, others do not express detectable quantities of the molecule. The glycoprotein is not restricted to hematopoietic cells and can be detected on lung, kidney, brain, and liver as well as cultured fibroblasts. Monoclonal antibodies against the glycoprotein cross-react with an antigen present on human cells. As described in the accompanying paper, the glycoprotein exists in two antithetical allelic forms and we show that it is identical to a polymorphic surface molecule independently characterized by Colombatti and co-workers.

Animals↗
PubMed1982

EMG feedback treatment of upper limb in hemiplegic stroke patients: a pilot study.

Poor prognosis for upper limb recovery of stroke survivors has not changed in at least 28 years; only 4% to 5% of patients regain arm function during or after the active rehabilitation phase. This pilot study included 37 patients randomly assigned to either an integrated behavioral-physical therapy treatment program including electromyographic feedback (experimental group) or a standard exercise physical therapy program of like duration and intensity (control group). Both groups showed clinically significant improvements that exceeded previously reported experience. The experimental technique appears to be more effective when upper limb involvement is not severe in a late case, or when treatment is started early (within 3 months poststroke) in a severe case. The rehabilitation community should quickly investigate the improved prospects of restoring a greater number of useful upper limbs in this often neglected group of hemiplegic patients.

Biofeedback, Psychology↗