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Biomedical subjects

M L Ng

Publications and source records attributed to M L Ng.

At least 91 records · Page 5Linked to original sources
PubMed1987

Involvement of microtubules in Kunjin virus replication. Brief report.

Induction of microtubulin paracrystals (Pc) by Kunjin (KUN) virus occurred after 15 hours post-infection and were often associated with convoluted membranes (cm) and virus particles. Vinblastine sulphate which disrupts microtubulin, had an inhibitory effect on the virus production when added during the viral latent period. When infected samples were extracted with Triton X-100 and analysed by SDS-PAGE, four viral proteins were observed.

Animals↗
PubMed1987

Ultrastructural studies of Kunjin virus-infected Aedes albopictus cells.

Ultrastructural changes in Aedes albopictus cells infected with Kunjin virus were characterized from 12 to 72 h post-infection. Early in infection (16h), there were no prominent ultrastructural changes except for an increase in the number of vacuoles in the cytoplasm. As the infection progressed the rough endoplasmic reticulum appeared to lengthen and whorls of fibres were observed within some vacuoles. Virus particles were observed in small numbers scattered in the cytoplasm between 24 to 30 h after infection. However, by 48 h, large numbers of morphologically mature virus particles were visible, usually in association with the rough endoplasmic reticulum, with the clusters of vesicles or with convoluted smooth membranes. Although no definite evidence of precursor particles or of budding of virions was obtained, the clusters of vesicles and the various membranous structures appeared to play a role in the morphogenesis of this virus. The results are compatible with the hypothesis that maturation of virus particles occurs within all these virus-induced structures.

Aedes↗
PubMed1987

The influence of higher temperature on dengue-2 virus infected C6/36 mosquito cell line.

Dengue-2 virus infection of C6/36 cells was studied at 28 and 37 degrees C. In infected cells maintained at 28 degrees C, syncytial development was seen on day 4 postinfection, whereas at 37 degrees C, extensive syncytial development was seen by 32 h. Extracellular virus titre was found to correlate with the cytopathic changes. Nine Dengue-2 virus specified proteins were observed in polyacrylamide analyses of cytoplasmic extracts of C6/36 infected cells. All the proteins were observed, although in varied intensities by 32 h postinoculation at 37 degrees C and only on day 4 postinoculation at 28 degrees C. The GP60 glycoprotein appeared at 32 h postinfection when the cells were maintained at 37 degrees C and became prominent only on day 5 at 28 degrees C. The results revealed that a higher temperature accelerated the onset of cytopathic effects, hastened the development of virus specified proteins, and also enhanced the titre of extracellular infectious virus. The importance of the accumulation of the envelope protein GP60 for the development of CPE was indicated.

Animals↗
PubMed1987

Enzyme immunoassay for simultaneous measurement of autoantibodies against thyroglobulin and thyroid microsome in serum.

A combined enzyme immunoassay (micro-ELISA) technique was established for measuring autoantibodies against thyroglobulin and thyroid microsome, involving the immuno-dot blot technique. Thyroglobulin and thyroid microsome antigens (1 g/L each) prepared from normal thyroids were spotted separately onto nitrocellulose membrane filter discs. Results by this method and those by immunofluorescence correlated well. The percentages of confirmed positives were 30% and 48% and the negatives were 58% and 46% (n = 50) for thyroglobulin and microsome, respectively. Testing these samples by gelatin agglutination gave a high percentage of false positives (up to 20%, n = 128) and hemagglutination testing yielded a high percentage of false negatives (up to 20%, n = 45). The titer of autoantibodies by the micro-ELISA technique was greater than by agglutination. This technique is highly specific and sensitive.

Autoantibodies↗
PubMed1984

Status of nutrition education in Canadian dental and medical schools.

To investigate the present status of nutrition education for dentists and physicians in Canada, we conducted a survey of the nutrition education programs in 10 Canadian dental and 16 medical schools in the academic year 1982-83. Seven of the dental schools and seven of the medical schools had a separate course in nutrition. The average duration of these courses was 22 hours for the dental schools and 26 hours for the medical schools. Nutrition education was integrated with another discipline in 4 of the dental schools and 11 of the medical schools. The average duration of this type of instruction was 14 hours for the dental schools and 18 hours for the medical schools. Six of the dental schools and eight of the medical schools employed a nutritionist/dietitian to provide instruction in nutrition. We recommend that courses in basic and applied clinical nutrition be incorporated throughout the curricula of Canadian dental and medical schools, and that personnel trained in clinical nutrition be employed to provide instruction in this area.

Canada↗
PubMed1983

Immunofluorescent sites in vero cells infected with the flavivirus Kunjin.

The sites of replication and of accumulation of viral macromolecules were examined using fluorescent antibodies to viral products and to cell organelles. Synthesis of envelope protein and its accumulation in a narrow rim around the nucleus were detected at 4 hours post infection; concurrently, a progressive change was observed in the rough endoplasmic reticulum from a fine to a coarse network emanating from around the nucleus. This change in the network was visible by light microscopy. The immunofluorescent sites of viral RNA synthesis, located by use of anti-double stranded RNA, extended from the perinuclear region in another fine network which included many small foci or vesicles; these sites were also visible by light microscopy late in infection. None of these changes were associated with any visible redistribution of actin, intermediate filaments or microtubules, and no nuclear involvement was detected. However, when microtubules were disrupted by vinblastine treatment of cells, the distribution of the immunofluorescent sites of viral RNA synthesis was modified and the virus yield was reduced by at least 10-fold. These results confirmed our biochemical studies showing separation of viral sites of RNA synthesis and translation, and the accumulation of envelope protein in nuclear-associated membranes. The relevance of these observations is discussed in relation to the reports of specific membrane structures induced in flavivirus-infected cells.

Animals↗
PubMed1983

Phenotypic changes in the flavivirus Kunjin after a single cycle of growth in an Aedes albopictus cell line.

The properties of Kunjin virus produced during acute infections of Aedes albopictus (Aal) mosquito cells were compared with those of the virus progeny from the C6/36 clone of mosquito cells and from Vero cells. Titres of 10(8) p.f.u./ml or greater were obtained from all cells, but significant haemagglutinin activity was associated only with progeny from Vero and C6/36 cells. Kunjin virus from Aal cells adsorbed to goose erythrocytes and blocked haemagglutination by virus from Vero or C6/36 cells. High titres of virus from Aal cells were obtained only when the cells were grown in the presence of 10% or higher concentrations of foetal calf serum, and large losses were encountered when this virus was concentrated by pelleting or by precipitation with polyethylene glycol, and during rate-zonal sedimentation through sucrose gradients. Because of these losses, and because of poor incorporation of [35S]methionine in Aal cells, only analytical amounts of labelled structural proteins were recovered. Electropherograms showed that the presumptive envelope protein E of Kunjin virus from Aal cells migrated more rapidly than E of virions grown in C6/36 and Vero cells, and that the core (C) and membrane-like (M) proteins were not detectably labelled. All the observed changes in phenotype were reversed during one cycle of growth in Vero cells.

Aedes↗
PubMed1982

Evaluation of different forms of community meeting in a psychiatric unit in Hong Kong.

In an in-patient psychiatric unit attached to a teaching general hospital in Hong Kong, community meetings went through doctor-directed and nurse-directed forms to develop into a non-directive one. The therapeutic value of these different forms was tested by retrospective and prospective studies. In the retrospective study the rates of ward incidents and discharge rates of in-patients before and during the three stages were compared. In the prospective study an ABA design was used with ten-week blocks of regular non-directive meetings, cessation of meetings and then resumption; ward incidents, discharge rates and ward atmosphere during these blocks were compared. Both the non-directive and nurse-directed forms were equally associated with a reduction in ward incidents, aggressive incidents showing the greatest tendency to change; ward atmosphere and patient discharge rates did not change with community meetings.

Evaluation Studies as Topic↗
PubMed1979

Proteins specified by togaviruses in infected Aedes albopictus (Singh) mosquito cells.

Yields of greater than 10(7) p.f.u./ml at 28 or 37 degrees C of the alphavirus Sindbis and the flavivirus Kunjin were obtained in the Aedes Albopictus (Singh) cell line, the latent periods being 4 to 6 and 10 to 12 h, respectively. Despite a high background of host protein synthesis, virtually all the virus-specified proteins of the flaviviruses Kunjin, Dengue-2 and Japanese encephalitis were labelled and resolved by slab gel electrophoresis of infected and uninfected cell proteins. In contrast, only one induced protein, of mol. wt. 30 000, was identified in cells labelled during Sindbis virus infection. The envelope glycoprotein V3 of Kunjin virus was resolved as a double band in samples of infected cytoplasm labelled with 3H-glucosamine, similar to that of carbohydrate-labelled V3 in vertebrate (Vero) cells. Attempts to reduce host protein synthesis selectively during labelling periods were unsuccessful using either a hypertonic inhibition block or treatment with 0.1 mu g actinomycin D per ml. The most efficient labelling of Kunjin virus-specified proteins was achieved at 37 degrees C in the presence of actinomycin D. The largest non-structural flavivirus protein NV5 migrated slightly faster than NV5 from infected vertebrate (Vero) cells. The small non-structural proteins NV1, NV1 1/2 and NV2 from infected mosquito cells were successively trimmed during post translational periods exceeding 70 min, compared to much shorter periods reported previously for post translational modifications of these proteins in vertebrate cells.

Aedes↗
PubMed1976

Physique, personality and mental illness in southern Chinese women.

A number of anthropometric measurements were made on Southern Chinese women. These were 317 schizophrenics, 44 with affective disorder, 47 neurotics and normal controls. All groups and sub-groups compared were matched for mean age and socio-economic status. It was found that the intercorrelations between body build, personality and type of mental illness were on the whole similar to those reported for Caucasians.

Acute Disease↗