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Biomedical subjects

C K Ho

Publications and source records attributed to C K Ho.

At least 163 records · Page 9Linked to original sources
PubMed1985

Enhanced production of human interferon-gamma by the use of a combination of inducers--phytohemagglutinin, picibanil and tumor promoting agent.

Phytohemagglutinin (PHA), picibanil (OK432) and tumor promoting agent (TPA) were tested in various combinations for optimal induction of human interferon-gamma (HuIFN-gamma). It was found that the use of a mixture of all 3 inducers resulted in IFN production 2-3 times higher than either PHA (10 micrograms/ml) in combination with TPA (5 ng/ml) or picibanil (10 micrograms/ml) alone. The IFN was produced by T lymphocytes and could be neutralized by specific IFN-gamma antiserum. It was pH 2.0 labile and species specific.

Biological Products↗
PubMed1985

Cytostatic effect of interferon-gamma and monocyte against a human carcinoma cell line.

Human interferon gamma (IFN-gamma) and normal peripheral blood monocytes had appreciable anticellular activities against KB cells such that in both cases, the rate of DNA synthesis, the number and percent viability of the cells were greatly reduced by 70-85% in about 3 days post-treatment. However, neither IFN-gamma nor monocyte alone was able to totally eliminate the tumor cells. Our results suggest that IFN-gamma and monocyte could effectively prevent the growth of residual tumor cells that would have escaped destruction when only one effector element was present.

Cell Adhesion↗
PubMed1984

Renal oncocytoma: new observations.

Renal oncocytomas are uncommon, benign tumors that can be treated by local excision or heminephrectomy; their preoperative differentiation from renal cell carcinoma, treated by radical nephrectomy, would be invaluable. A particularly important finding, a central scar--not stressed in previous reports, is frequently demonstrated by CT examination. We evaluated radiographic studies of 18 pathologically confirmed cases of oncocytoma and compared findings with results of CT, sonography, and angiography studies of 18 renal cell carcinoma cases. Oncocytomas can be suggested if a stellate scar is identified within an otherwise homogenous tumor on ultrasound (US) and CT; if the mass appears homogeneous but no scar is present, angiography should be performed. An oncocytoma can be suggested in these cases if a spoke-wheel configuration and homogeneous blush are present. These criteria, which are reliable only if the mass is 3 cm or larger, would have resulted in the correct diagnosis of oncocytoma in 16/18 cases.

Adenocarcinoma↗
PubMed1982

Decreased transport of ornithine across the inner mitochondrial membrane as a cause of hyperornithinaemia.

Hyperornithinaemia due to a transport of ornithine across the inner mitochondrial membrane was demonstrated in three patients by measuring ornithine uptake by fibroblast mitochondria. Particulate compartments and soluble cytoplasm of fibroblasts were separated by a slight modification of the digitonin method of Zuurendonk and Tager. Patients' fibroblast pellet fraction contained significantly less radioactivity than control fibroblast pellet fraction after incubation of fibroblasts with [14C]-ornithine. Since neither of the patients was deficient in ornithine-delta-oxoacid aminotransferase, we concluded that in these hyperornithinaemia patients a defect exists for transport of ornithine across the inner mitochondrial membrane. The exact nature of this transport defect remains to be elucidated.

Amino Acid Metabolism, Inborn Errors↗
PubMed1982

Lithium and chlorpromazine in psychotic inpatients.

A sample of recently hospitalized psychotic patients was assigned to treatment with lithium or chlorpromazine in a double-blind drug trial. Several diagnostic systems were used to characterize the patients. No relationship was found, regardless of criterion system used, between diagnosis and differences in drug effectiveness; specifically, the presence of "schizophrenic" symptoms did not predict a poor response to lithium. Among patients with physical overactivity, those treated with lithium terminated earlier and had poorer outcome than those treated with chlorpromazine. In patients who were not overactive, the two drugs were equally effective, and chronically psychotic patients had poorer outcomes regardless of drug. Lithium may be an effective treatment for acutely psychotic patients who are not overactive. The use of a lithium trial as a diagnostic tool may be unwarranted.

Adult↗
PubMed1982

Secretin and vasoactive intestinal peptide acutely increase tyrosine 3-monooxygenase in the rat superior cervical ganglion.

We have previously shown that stimulation of the preganglionic cervical sympathetic trunk leads to an acute increase in tyrosine hydroxylase (TyrOHase) activity in the rat superior cervical ganglion. This increase appears to be mediated in part by acetylcholine and in part by a second neurotransmitter. As a first step in an attempt to determine the identity of this noncholinergic transmitter, we have examined the ability of a number of neuropeptides to increase ganglionic TyrOHase activity in vitro. Secretin and vasoactive intestinal peptide (VIP) both stimulated TyrOHase activity, whereas angiotensin II, bombesin, bradykinin, cholecystokinin octapeptide, glucagon, insulin, luteinizing hormone-releasing hormone, [D-Ala(2), Met(5)]enkephalinamide, motilin, neurotensin, somatostatin, and substance P produced no effects. Secretin produced a significant increase in TyrOHase activity at 1 nM and a maximal elevation at 0.1 muM. VIP produced a significant increase at 0.1 muM and a near maximal effect at 10 muM. Although secretin was about 2 orders of magnitude more potent than VIP, it produced a significantly smaller maximal increase in enzyme activity. Incubation of ganglia with both secretin (10 muM) and VIP (10 muM) produced an increase in TyrOHase activity that was not significantly different from that produced by VIP alone. The stimulatory effects of secretin and VIP were reversible within minutes after removal of the peptides. Neither incubation of intact ganglia with the cholinergic antagonists hexamethonium and atropine nor prior decentralization of ganglia altered the response to the peptides. Thus, the data demonstrate that secretin and VIP acutely increase TyrOHase activity in the superior cervical ganglion and suggest that they produce this effect by acting directly on ganglionic neurons. It remains to be determined whether secretin or VIP or a related peptide is released during preganglionic nerve firing and whether one or more of these peptides is responsible for the noncholinergic elevation of TyrOHase activity produced by preganglionic nerve stimulation.

Acetylcholine↗
PubMed1982

Myotonic dystrophy: HLA antigens and mitogen stimulated lymphocyte responses of a black American family.

A Black American family of four generations with 29 members was studied. Six family members spanning two generations were affected with myotonic dystrophy. HLA A, B, C and DR antigen specificities were determined for each family member using local typing trays. Twelve HLA haplotypes were identified in the family. No significant association was found between the disease and any HLA antigenic type or haplotype. This finding suggests that the involvement of the major histocompatibility complex in the etiology of myotonic dystrophy is unlikely. The cellular responses to twenty-eight family members and 20 unrelated Black Americans to phytohemagglutinin (PHA), Concanavalin A (Con A) and pokeweed mitogen (PWM), each in three concentrations, were tested with mononuclear cells prepared from peripheral blood. There was a significant difference in responses of the affected family members as compared to the unaffected family members and the unrelated Black Americans. The PHA and PWM responses of the unaffected family members are not significantly different from those of the unrelated Black American controls; however, the Con A responses of the unaffected family members are significantly higher than those of the control group at the lowest Con A dosage. The possible systemic defects of cytoskeletal structures of the affected family members are discussed.

Black People↗
PubMed1981

Racing thoughts in psychiatric inpatients.

Racing thoughts, which have been previously described in schizophrenia and mania, were found to be equally prevalent in hospitalized depressed and manic patients. Racing thoughts are rare in schizophrenics who do not have an affective syndrome and more common in schizoaffective patients. The symptom is associated with disturbed concentration. It is experienced as pleasant by manic patients and as unpleasant by depressed patients. Racing thoughts may be important in the understanding of affective illness.

Adolescent↗
PubMed1981

Infection of canine mononuclear leucocytes by measles virus: possible mechanism of protection from canine distemper.

Measles virus was shown to be infectious to canine lymphocytes from peripheral blood as well as from different lymphoid tissues, and the same held true for canine macrophage cultures prepared from peripheral blood. The susceptibility of these leucocytes to measles virus was comparable with that of canine distemper virus. These observations supported the suggestion that interference with canine distemper virus by measles could be a possible mechanism of the heterotypic immunity observed in dogs.

Animals↗
PubMed1980

Prenatal diagnosis of metachromatic leukodystrophy in a family with pseudo arylsulfatase A deficiency by the cerebroside sulfate loading test.

Prenatal diagnosis was requested by a family at risk for metachromatic leukodystrophy (MLD). An examination of the family leukocyte arylsulfatase A profile revealed that the mother had pseudo arylsulfatase A deficiency. Cultured amniotic fluid cells were deficient in arylsulfatase A, so two possibilities were indicated: the fetus was affected with MLD or had the pseudodeficiency phenotype. The only known biochemical test to differentiate the two enzyme deficient phenotypes is cerebroside sulfate loading of growing fibroblasts. The pseudodeficient cells hydrolyze the incorporated sulfatide as efficiently as control cells, whereas MLD cells show no hydrolysis. Application of this test to the at risk cultured amniotic fluid cells resulted in appreciable uptake of the sulfolipid, but no hydrolysis. Control amniotic fluid cell cultures hydrolyzed 82 to 95% of the incorporated sulfatide. Therefore, an affected fetus was indicated. Fibroblasts derived from the aborted fetus showed a deficiency of arylsulfatase A and a similar inability to hydrolyze cerebroside sulfate in the loading test. The loading technique allowed the prenatal diagnosis of MLD when the arylsulfatase A analysis was equivocal.

Amniotic Fluid↗
PubMed1980

Immune mechanisms against canine distemper. III. Role of complement lysis in the immunity and persistent infection of canine distemper virus.

Antibody-mediated complement lysis of Vero cells and canine macrophages infected with canine distemper virus (CDV) was demonstratee in an in vitro 51Cr release assay. This cytolytic activity was found to be highly efficient and was optimal under conditions which favoured the capping of redistribution of surface viral antigens. A prozone was observed in the presence of high antibody concentration and could not be eliminated by repeated washings. By tagging antibody-coated target cells with 125I-labelled staphylococcus protein A, it was found that the extent of protein A binding was parallel to the degree of cytotoxicity suggesting that the mechanism of this prozone effect was similar to that of a precipitation test.

Animals↗
PubMed1979

Mechanisms of heterotypic immunity against canine distemper.

Hep-2 cells infected with measles virus (MV) for as short as 6 h became refractory to superinfection with canine distemper virus (CDV) but not to vesicular stomatitis virus (VSV). The exact mechanism of such interference is unknown but probably occurs after virus attachment and penetration. These results verify the suggestion that virus interference may be a mechanism of heterotypic protection against canine distemper.

Animals↗
PubMed1979

Pancoast's tumor: irradiation or surgery?

Seventy-three patients with Pancoast's tumor treated at the University of Maryland Hospital between 1955 and 1978 were reviewed. Three were 34 squamous cell carcinomas, 13 undifferentiated, 10 adenocarcinomas, 4 mixed adenosquamous, 1 alveolar cell, and 11 undetermined. Twenty-nine patients received irradiation, with 7% survival at 3 years; 19 patients underwent preoperative irradiation followed by en bloc resection of chest wall, with 23% survival at 3 years; 5 patients underwent extended resection, with 60% survival at 3 years; and 18 patients underwent operation followed by irradiation, with 7% survival at 3 years. Retrospective staging of 42 patients undergoing operation indicated that 22 (52%) were inoperable. Prognosis was related to staging of the disease, the extent of local invasion, nodal involvement, cell type, and adequacy of operation.

Adult↗
PubMed1979

A new plaque system for canine distemper: characteristics of the green strain of canine distemper virus.

A Vero cell adapted Green strain of canine distemper virus (CDV) was tested for its plaque-forming capacity in different cell lines. Plaque formation was observed in HEp-2, BS-C-1, and HeLa cells but not in Vero or dog kidney cells even though replication and cytopathology were observed in the latter cell types. In the cells in which the virus was capable of producing plaques, the plaques were observed within 24 h post infection and continued to increase in size with subsequent cellular destruction such that by 72 h postinfection the size of the plaques approached 0.5 mm. With the use of the plaquing technique, it was possible to demonstrate the thermal lability of the virus as well as the kinetics of adsorption. Thus, it was shown that the half-life of the virus was 125 min at 25 degrees C, 75 min at 35 degrees C, and 65 min at 37 degrees C. The rate of adsorption of CDV to HEp-2 cells was 17.2% in 30 min at 37 degrees C and continued slowly for 4 h before completion. Application of this rapid plaque-forming assay to plaque-reduction tests for CDV antibody and for CDV-infected cells by the infectious center assay are described.

Animals↗
PubMed1979

Long-term culture of canine peripheral blood monocytes in vitro.

Various cultural conditions were assessed for their ability to maintain canine peripheral blood monocytes in vitro. Approximately ten days after incubation of peripheral blood leukocytes in Earle's minimum essential medium supplemented with homologous red cell lysates and normal horse serum, virtually a pure macrophage culture was obtained which could then be maintained for about two months. This culture was judged to be pure by surface marker analysis and their phagocytic activity. The number of monocytes could be increased by injecting the dogs with a chloroform extract from Listeria monocytogenes prior to collection of the blood.

Animals↗
PubMed1979

Immune mechanisms against canine distemper. II. Role of antibody in antigen modulation and prevention of intercellular and extracellular spread of canine distemper virus.

Specific antibody was shown to be highly effective in neutralizing extracellular canine distemper virus (CDV) as well as preventing the intercellular spread of this virus. Thus, relatively low levels of antibody neutralized 1 x 10(5) TCID50 of extracellular CDV and the development of plaques or CPE in Hep-2 and Vero cells respectively could be prevented even when up to 5% of the cells were infected. This inhibition of CPE and virus spread was most pronounced when antibody was added early but could still limit the degree of CPE if added as late as 48 h post-infection. This anti-viral activity was observed in different cell types including canine macrophages, cells normally infected with CDV in vivo. Prolonged exposure of infected target cells to high concentrations of antibody led to redistribution of surface viral antigens and their subsequent disappearance. The possible role of antibody in the defence against, and/or recovery from CDV and the mechanism(s) by which antibody may aid in recovery are discussed.

Animals↗