Biomedical subjects
Publications and source records attributed to L P Chao.
The human body has frequently been used as a vehicle for illicit drug smuggling. The anatomic site of concealment is usually the gastrointestinal tract. We report a case in which the vagina was used for this purpose. Removal of the package containing the drug was very difficult and had to be accomplished by the use of obstetric forceps.
Hybridomas have been prepared from active B cells in lymphoid tissue draining lesions of Crohn's disease (CD) and ulcerative colitis (UC), by fusion of fresh mesenteric lymph node suspensions with the murine JK myeloma. Two hundred and fifty nine immunoglobulin secreting hybridomas have been obtained from nine patients. The antibodies have been screened for binding to food antigens, sections of human gut, and bacteria including two unidentified acid fast isolates from CD lymph nodes. Autoantibodies, and antibodies to food antigens implicated by others in the aetiology of CD were rare, comprising 1.2%, and 2.5% respectively. Most donors yielded none of these. Thus neither food antigens nor autoantigens are major antigenic stimuli in nodes draining inflammatory bowel disease. On the other hand between 19% and 83% of supernatants from different donors bound to one or more bacterial genus. The mycobacteria and the CD isolates were amongst the genera to which most antibodies bound, though binding to E coli was more frequent. Significantly more CD than UC derived supernatants bound to BCG. As mycobacteria are not though to be part of the normal bowel flora, the high percentage of hybridomas secreting antibodies which bind to this genus is surprising.
Botulism is induced by botulinum toxin and the mechanism of the disease is unknown. In another study, a fatal autoimmune disease was produced in animals by immunization with a fraction of choline acetyltransferase. When these two syndromes are compared, numerous similarities are observed. It is postulated that botulism toxin acts as an initiator for the autoimmune disease by catalyzing in vivo the formation of the pathogenic fraction of choline acetyltransferase.
Peritoneal leucocytosis, with an increased percentage of eosinophils, was found in mice which had been infected with Schistosoma mansoni for 7 weeks or longer. Specific IgG against worm and egg antigens increased in peritoneal fluids and their corresponding sera respectively 5 and 7 weeks after infection. An intraperitoneal challenge with schistosomula elicited neutrophilia in all mice regardless of immune status, as well as infiltration of eosinophils and macrophages in infected mice. The secondary eosinophilia occurred in mice previously infected for 1 week or longer, whereas the infiltration of macrophages occurred only after worms from the primary infection had started laying eggs. Unlike the eosinophilia the macrophage response required infection with bisexual populations of cercariae. Injection of previously infected mice with Escherichia, Trichinella or Toxocara failed to increase the proportions of eosinophils and macrophages. Schistosomula-induced eosinophilia could be elicited in passively sensitized mice. Intraperitoneal injection of PBS extract of adult worms elicited eosinophilia in infected mice and neutrophilia in normal mice. Two chromatographic fractions induced eosinophilia and the third only neutrophilia. The relevance of these observations to host response to S. mansoni infections is discussed.
uinea pig antiserum specific to the purified bovine choline acetyltransferase was used to demonstrate the localization of this enzyme in rabbit forebrain by the peroxidase-antiperoxidase immunohistochemical method. Choline acetyltransferase was localized in olfactory bulb, olfactory tract, olfactory tubercle, piriform cortex, septum, diagonal band, basal ganglia, thalamus, hypothalamus, subthalamus, habenula, cerebral cortex, hippocampal region, corpus callosum, internal capsule, fornix, longitudinal striae and other areas. The findings reflect the distribution of cholinergic axons and, possibly, their terminals. These observations correlate well with biochemical determinations of choline acetyltransferase and with previously proposed cholinergic pathways.
In order to further characterize the reaction mechanism of brain ChAc in its purified form, we have investigated the reverse reaction of ChAc in terms of pH optimum, salt effects, and substrate kinetics using a radiochemical assay. We directly measured the reaction product acetylcoenzyme A which was separated from the substrate ACh by a cation exchange column. Dowex 50W-X8 (Na+ form). The reverse reaction of ChAc was linear with incubation time up to 40 minutes, and with enzyme protein concentration up to 5 micrograms. It had a pH optimum at 7.0. At 0.22 M the monovalent chloride and bromide salts activated the reverse ChAc activity by 23-47% but the fluoride and iodide salts inhibited the reverse enzyme activity by 10-30%. Kinetic studies in the absence of salt showed that KACh was 0.62 +/- 0.06 mM, KCoA . SH was 12.68 +/- 1.21 microM, and Vmax was 11.6 +/- 1.0 nmol AcCoA/mg protein/min. These data are in disagreement with the values reported on partially purified ChAc from bovine brain by Glover and Potter [1971] and Hersh [1980]. This indicates that further investigations are necessary to clarify or resolve these differences.
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Guinea pig antiserum specific to purified bovine choline acetyltransferase was found to cross-react with human enzyme. The peroxidase-antiperoxidase immunohistochemical method was then used to demonstrate the localization of choline acetyltransferase in formalin-fixed and paraffin-embedded human cerebellum from normal as well as from Huntington's disease brains. Choline acetyltransferase was localized exclusively in the mossy fibers and the glomeruli of the cerebellar folia. These immunohistochemical findings reveal the distribution of cholinergic axons and their terminals. The results are not only similar to our previous studies using the same method on the localization of choline acetyltransferase in rabbit cerebellum, but also demonstrate that some mossy fibers are cholinergic as suggested by others.
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Guinea pig antiserum specific for purified bovine choline acetyltransferase has been shown to cross-react with rabbit enzyme. We used the peroxidase-antiperoxidase immunohistochemical method to demonstrate the localization of choline acetyltransferase in formalin-fixed and paraffin-embedded sections of rabbit spinal cord and cerebellum. In the spinal cord, in agreement with our and others' previous results using immunofluorescent techniques, choline acetyltransferase was found in the cell bodies of the ventral horn motor neurons. In the cerebellum, choline acetyltransferase was localized exclusively in the mossy fibers and the glomeruli of the cerebellar folia. The immunohistochemical findings in the cerebellum reveal the morphological detail of cholinergic axons and their terminals. The results are consistent with published biochemical data on the cerebellar distribution of choline acetyltransferase.
No multiple forms of choline acetyltransferase were found in extracts of human, mouse, rabbit, guinea pig, cat, and rat brain. A single form of this enzyme only was also demonstrated in bovine nervous tissue, including brain, dorsal and ventral roots, spinal cord, and femoral nerve. The difference from other published findings is believed to be due to ammonium sulfate fractionation, which was not used in the present study. In addition, multiple forms of the enzyme were obtained by others using isoelectric focusing, whereas this study employed gel filtration. Choline acetyltransferase was highly purified form mouse brain using a procedure similar to that used for the enzyme from bovine brain. The steps involved: (1) making an acetone-chloroform powder from whole mouse brains, (2) extracting the powder and chromatographing the soluble fraction with organomercurial Sepharose, (3) passing the enzyme solution through a column of DEAE-cellulose, (4) eluting from hydroxyapatite, and (5) removing contaminants by subunit exchange chromatography. The final preparation was essentially homogeneous as revealed by polyacrylamide gel electrophoresis.
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Suspensions of erythroctes from certain marine fish (cod, saithe, haddock and mackerel) were 4--16 times more sensitive than human or horse erythrocytes to staphylococcal delta-haemolysin. Cod erythrocytes were lysed rapidly by delta-haemolysin and the titres of haemolysin were independent of the temperatures at which the tests were incubated, over the range 0--37 degrees C. Fish erythrocytes were not lysed by purified alpha- and beta-haemolysins and no synergistic action was found between beta- and delta-haemolysins. In blood agar-overlay plates, the zones of lysis that developed in cod blood agar were larger and clearer than those that developed in human or horse blood agar.
The purpose of the present experiment was to determine if there is a factor in serum of patients with myasthenia gravis (MG) that interferes with binding of (125I)-alpha-bungarotoxin to acetylcholine receptors of normal mouse diaphragm. Diaphragms were incubated aerobically for 1 hour in either Krebs-Henseleit solution, MG serum, or control serum, and then (125I)-alpha bungarotoxin was added for 2 further hours at a concentration of 1 mug/ml. After 12 rinses in Krebs-Henseleit solution for another hour, radioactivity was counted. Binding after exposure to MG serum was compared to that obtained after exposure to Krebs-Henseleit solution or control serum. Sixteen sera from 14 controls, 18 sera from 15 patients with moderate generalized MG, and seven sera from seven patients on alternate-day prednisone therapy (six with severe generalized MG, one with myasthenic syndrome) were tested by this method. No significant difference in alpha-bungarotoxin binding was observed between normal mouse diaphragm incubated in MG sera and those incubated in control sera.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.