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Biomedical subjects

H Ng

Publications and source records attributed to H Ng.

At least 19 recordsLinked to original sources
PubMed2001

Influenza revaccination of elderly travelers: antibody response to single influenza vaccination and revaccination at 12 weeks.

The antibody response to a single influenza vaccination and the effect of influenza revaccination was assessed in healthy elderly persons. Travelers > or =65 years old who had received influenza vaccine before travel were enrolled in the study and were offered a second vaccination after 12 weeks. Geographic and age-matched control subjects received a single vaccination. A second influenza vaccination was not associated with increased adverse effects. There was no significant difference between log(10) hemagglutinin-inhibiting (HI) antibody titers or an HI antibody titer > or =1:40 (considered to be protective) in 28 control subjects and 28 revaccinated travelers for any antigen. Probable protection for influenza A antigens remained high 24 weeks after a single immunization and revaccination (A/Sydney/05/97 [H3N2], 92% and 96%, and A/Beijing/262/95 [H1N1], 80% and 96%, respectively). Response to B/Harbin was less throughout the study. A/Sydney antibody titer was lower with more times vaccinated in the previous 5 years. Therefore, a second vaccine did not enhance the immune response.

Aged↗
PubMed2000

AIDS in the media.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Sequence analysis and expression of a cDNA clone encoding a 98-kDa allergen in Dermatophagoides farinae.

BACKGROUND: The important dust mite allergens identified to date are of molecular weights ranging from 14 to 60 kDa. Our previous protein study indicated that the 98-kDa native paramyosin in Dermatophagoides farinae mite showed IgE reactivity with 82% of the mite-sensitive asthmatic patients suggesting that it is a novel major mite allergen. This study described the isolation and characterization of the cDNA clone encoding the 98-kDa mite allergen. METHODS: A Dermatophagoides farinae cDNA library was constructed in lambda ZAPII vector and the library was immunoscreened with a monoclonal antibody 642. The cDNA insert was sub-cloned into M13 sequencing vector for single-stranded sequencing. The whole cDNA insert was expressed in pGEX-2T Escherichia coli expression system as a fusion protein with GST. The allergenicity of the recombinant peptides was tested by skin tests and IgE immunoassay. The IgE and IgG immunoassays were performed with sera from 20 mite-allergic patients. RESULTS: The cDNA clone Df642 was 2134 bp long, coding for a polypeptide of 711 amino acid residues. Protein sequence analysis and alignment confirmed that the deduced polypeptide is a mite paramyosin which is truncated slightly at the N- and C-terminuses. In vivo skin tests and in vitro IgE-binding study showed that 62% (13/21) and 50% (10/20) of the mite-sensitive asthmatic patients reacted positively with the recombinant Dermatophagoides farinae paramyosin, respectively. CONCLUSION: The study indicated that 98-kDa mite paramyosin is an important allergen.

Adolescent↗
PubMed1999

Recurrence and survival analyses of 1,115 cervical cancer patients treated with radical hysterectomy.

Many clinicopathological factors of cervical cancer are still controversial in their prognostic significance. The case records of 1,115 patients who received radical hysterectomy at the Veterans General Hospital, Taipei, from 1980 to 1989 were collected to evaluate prognosis-related factors by univariate and multivariate analyses. The pathology was reviewed retrospectively by one pathologist. Ten parameters known to be prognostic in the literature were included for analysis. Univariate analysis showed that patients with all these factors had higher recurrence rates. However, when the effects of parametrial invasion, progressive stage and stromal invasion were weighed against the presence of lymph node metastasis, their influence on recurrence became unimportant. Nevertheless, these factors still influenced prognosis when there was no lymph node metastasis. Multivariate analysis of both recurrence and survival time in the patients with squamous cell carcinoma shared a consensus that pelvic lymph node metastasis and deep stromal invasion were significant risk factors. We conclude that these simplified and consistent results obtained by multivariate analysis provide a basis for subclassification of patients to predict prognosis and change therapy.

Adenocarcinoma↗
PubMed1999

Granulocyte colony-stimulating factor on the growth of human ovarian carcinoma cells in vitro.

Granulocyte colony-stimulating factor (GCSF) is a member of a family of glycoprotein hormones that stimulates the proliferation and differentiation of hematopoietic cells in vivo and in vitro. In ovarian cancer chemotherapy, GCSF is used clinically to build up bone marrow function after severe cytotoxicity to granulocytes by chemotherapy. Little is known about the effects of these cytokines on the growth of cancer cells. To study the influence of GCSF on the proliferation of ovarian cancer cells in vitro, five established ovarian cancer cell lines (OC-89-VGH, OC-117-VGH, OCPC-2-VGH, NIH-OVCAR-3, and NIH-SK-OV-3) were treated with the concentration ranging from 0.1 pg to 10 ng GCSF for 5 days and compared with vehicle control. In addition, we also examined the effect of GCSF (0. 01-1.0 ng) on eight primary cultures of fresh ovarian cancer tissues. Cell viability after treatment was measured by Cell Titer AQueous assay and expressed as a percentage of untreated control cultures. A decrease in cell growth (75-85%) was observed in OC-89-VGH, OC-117-VGH and OCPC-2-VGH cell lines while NIH-OVCAR-3 and NIH-SK-OV-3 cells showed minimal growth stimulation. However, all dose-response curves were nonsignificant, suggesting indirect effects. In the eight fresh tumor primary cultures treated with GCSF, no statistical significant difference in growth was observed. In conclusion, our data suggest that GCSF has little or no growth-modulatory effect on human ovarian carcinoma in vitro. Therefore, the clinical use of GCSF is unlikely to have a direct effect on tumor growth.

Cell Division↗
PubMed1997

Synthesis and smooth muscle calcium channel effects of dialkyl 1,4-dihydro-2,6-dimethyl-4-aryl-3,5-pyridinedicarboxylates containing a nitrone moiety in the 4-aryl substituent.

A group of dialkyl 1,4-dihydro-2,6-dimethyl-4-¿3-(or 4-)[[(Z)-N- oxo-N-[4-substituted-phenylmethylene (or vinylmethylene)]-lambda 5- azanyl]phenyl¿-3,5-pyridinedicarboxylates 7a-n were synthesized. Reaction of the C-4 nitrophenyl compounds 6a-d with an aryl Grignard reagent afforded the corresponding nitrone derivatives 7a-e. Alternatively, reaction of the aryl hydroxylamine compounds 8a-b prepared by reduction of the nitrophenyl compounds 6c-d with Zn/NH4Cl, or the aryl hydroxylamine compounds 8c-d prepared by reduction of the nitrophenyl compounds 6e-f with 5% rhodium-on-charcoal and 65% hydrazine hydrate, with a 4-substituted-benzaldehyde, benzaldehyde or acrolein afforded the respective nitrone compounds 7f-n. In vitro calcium channel (CC) antagonist activities were determined using the guinea pig ileum longitudinal smooth muscle assay. This class of compounds containing a nitrone moiety on the 1,4-dihydropyridine C-4 phenyl ring exhibited CC antagonist activities (10(-5) to 10(-9) M range) relative to the reference drug nifedipine (IC50 = 1.43 x 10(-8) M). Structure-activity relationships showed that the position of the nitrone moiety on the C-4 phenyl ring was a determinant of CC antagonist activity where the potency order was always meta-nitrone > para-nitrone. The effect of the ester alkyl substituent was variable depending upon whether the nitrone substituent was at the meta or para-position (meta-nitrone, Et > i-Pr approximately Me; para-nitrone, i-Pr > Me approximately Et). In the diethyl ester series of compounds having a meta-nitrone moiety, the difference in potency for the various R2-nitrone substituents varied by a factor of 15-fold (IC50 = 1.51 x 10(-7) to 9.84 x 10(-9) M range) (4-Cl-C6H4- > or = 4-Me-C6H4- approximately C6H5- > or = 4-O2N-C6H4- 4-F3C-C6H4- > > CH2 = CH-). Whole-cell voltage-clamp studies using isolated guinea pig ventricular myocytes indicated that the 4-¿3-[(Z)-N-oxo-N-(phenylmethylene)-lambda 5-azanyl]-phenyl¿ compound 7c (10 microM) is a calcium channel antagonist which decreased the calcium current (ICa).

Animals↗
PubMed1997

Alzheimer-type of pathological changes in Chinese.

There has been no previous description of the pathological features of Alzheimer's disease and little description of Alzheimer-type changes in Chinese brains. In this study, we examined the brains of 17 cases of Alzheimer's disease and concurrently 95 consecutive autopsy cases of non-demented patients aged above 60. Six standard regions of the brains were stained for beta-amyloid immunostaining, Bielschowsky and Bodian. Neuritic plaques, neurofibrillary tangles and diffuse plaques were quantified as per mm2. The Alzheimer's disease brains exhibited a marked increase of neurodegenerative changes over the non-demented brains. Plaque counts were similar to those proposed by Khachaturian (1985; Arch. Neurol. 42: 1097-1105) and CERAD, although the distribution of tangles was more variable with some regions of the neocortex containing few or no tangles. For the non-demented brains, overall neuritic plaques were seen in 31% and neurofibrillary tangles were seen in 42% of cases, with the overall plaque score being 1.8 per mm2 and tangle score being 0.7 per mm2. No age-dependent variation of plaque count and tangle count could be demonstrated in this group of elderly brains. Comparison with similar studies of Caucasians suggests that neuritic plaques and neurofibrillary tangles were less frequently encountered in aging Chinese brains than among the western populations.

Aged↗
PubMed1994

An anterior intradural neurenteric cyst of the cervical spine: complete excision through central corpectomy approach--case report.

The case of a cervical intraspinal neurenteric cyst in a 6-year-old boy is reported. The anterior intradural location of the cyst was confirmed by preoperative magnetic resonance imaging. Complete excision of the cyst was achieved through the anterior central corpectomy approach. The vertebral defect was reconstructed with autogenous fibular graft. The child made a complete neurological recovery without a mechanical problem either at the neck or at the graft donor site.

Bone Transplantation↗
PubMed1993

Host-specific transcription of baculovirus genes.

We examined the differential replication of Autographa californica multicapsid nuclear polyhedrosis virus (AcMNPV; Family: Baculoviridae) in Spodoptera frugiperda (SF) and Bombyx mori (BM) cell lines. Our previous studies have shown that infection of BM cells is abortive; infectious progeny is not produced, and although virogenic stroma is produced, complete virions or inclusion bodies are not assembled. We designed the present study to determine the extent of infected-cell-specific polypeptides (ICSPs) and viral DNA synthesis in the abortive infection and to see if restriction of virus replication in BM cells is due to a block at the transcriptional level. Pulse-labeling studies showed that a majority of the ICSPs detected in productive SF cells were not synthesized in BM cells. Many of these ICSPs were virion components. Viral DNA replicated in BM cells but more slowly and at a much lower level than in SF cells. Northern blot analysis showed that i) AcMNPV immediate-early gene (IE-1) was transcribed in BM cells at higher levels than in SF cells; ii) a delayed-early gene (dnapol) and a late gene (cap) were transcribed at much lower levels in the abortive infection; and iii) a very late gene (polh) was transcribed at extremely low levels in BM cells. We conclude that virus replication in BM cells is primarily restricted during or prior to the delayed-early stage and occurs at the transcriptional level. It appears that the late and very late effects observed are consequences of the primary block.

Animals↗
PubMed1989

Foetus in foetu--a case report.

A three-month old baby presented to the Paediatric Department with a problem of abdominal distension. Clinically, he had a large right abdominal mass which on investigations suggested a teratomatous lesion. At operation, a foetus-like tumour mass was located in the retroperitoneal space. A diagnosis of foetus in foetu was made. A close differential of a retroperitoneal teratoma is discussed and comparison with confirmed cases made.

Abdominal Neoplasms↗
PubMed1982

Effect of growth conditions on heat resistance of Arizona bacteria grown in a chemostat.

The effects of various growth conditions on the heat resistance of Arizona bacteria grown in a continuous-culture device (chemostat) were studied. Using either glucose, NH4Cl, NaH2PO4, or MgCl2 as the rate-limiting nutrient, it was found that the heat resistance, in all cases depended on the dilution rate and, hence, growth rate of the culture. Cells grown at high dilution rates were less heat resistant than those grown at low dilution rates. If, however, the dilution rate was maintained at a constant rate, the higher the growth temperature, the more heat resistant were the cells. Also at any given dilution rate, the cells were most heat resistant when grown at a near neutral pH. Most survival curves were biphasic in shape, indicating the presence in the population of two fractions of cells, one fraction being more resistant than the other. The size of the more heat-resistant fraction varied from almost 100% in very slow-growing cultures to practically 0% in cultures grown at a dilution rate of 0.67 h-1.

Ammonium Chloride↗