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Biomedical subjects

C M Wong

Publications and source records attributed to C M Wong.

At least 109 records · Page 6Linked to original sources
PubMed1987

Estrogen receptor-binding affinity and cytotoxic activity of three new estrogen-nitrosourea conjugates in human breast cancer cell lines in vitro.

The hypothesis that more selective antitumor activity may be achieved by cytotoxic agents which selectively bind to estrogen receptors (ER) in human cancer cells was tested. We have synthesized three nitrosourea derivatives of estradiol or hexestrol, and compared the ER binding affinity and cytotoxic activity of these compounds against ER-positive and -negative breast cancer cell lines in vitro. Specific binding to ER in the cytosol of MCF-7 human breast cancer cells was demonstrated in these conjugates: 17 alpha-CNU greater than 17 beta-CNU greater than HEX-CNU greater than lomustine (CCNU). The order of cytotoxicity of these derivatives against human breast cancer cells appeared to correlate with their binding affinity to ER. All three estrogen nitrosourea conjugates were more cytotoxic than CCNU, a clinically useful antitumor nitrosourea which does not bind to ER. The contribution of the estrogen moiety to the cytotoxicity of 17 alpha-CNU was demonstrated by the greater activity of the conjugate than that of a combination of estrogen and CCNU. However, cytotoxicity of these compounds against the receptor-positive MCF-7 and receptor-negative Evsa-T human breast cancer cell lines was similar. The latter finding suggested that cytotoxicity of these conjugates may not be mediated through ER. The difference in stability of these nitrosourea conjugates in aqueous buffer may partly explain their differences in cytotoxicity.

Antineoplastic Agents↗
PubMed1987

Mental health and work stress: a comparison of response patterns in executives and clerical workers in Hong Kong.

Mental health and work stress among 344 clerical (and secretarial) workers and 185 executives (96 managers and 89 executives) in Hong Kong was studied. No overall difference was found between clerical workers and executives in mental health and coping ability when sex was controlled for. Clerical workers, however, reported fewer interests, more problems in accepting others' values, and more dissatisfaction with work context. Female managers/executives were shown to be a high risk group, reporting more problems in mental health, coping, and work context than their male counterparts. Mental health was strongly associated with each of the work stress factors studied. A significant interaction between sex and nature of job was noted in predictors of mental health. The interaction of coping, context, and mental health is discussed.

Adaptation, Psychological↗
PubMed1986

Effect of ginsenosides Rg1, Rc and Rb2 on hormone-induced lipolysis and lipogenesis in rat epididymal fat cells.

Ginsenosides Rb2, Rc and Rg1 suppressed corticotropin-induced, dibutyryl cyclic AMP-induced and epinephrine-induced lipolysis with the relative potencies Rb2 greater than Rc greater than Rg1. The inhibition of corticotropin-induced lipolysis by ginsenoside Rg1 could not be overcome by increasing the dose of the lipolytic hormone while that of ginsenosides Rc and Rb2 was nearly abolished by corticotropin at a dose of 40 nM which by itself produced maximal lipolysis. Dibutyryl cyclic AMP-stimulated lipolysis was also inhibited. Only ginsenoside Rb2 suppressed glucagon-induced lipolysis. All three ginsenosides did not inhibit basal lipolysis or basal incorporation of D-[3-3H]glucose into lipids. Insulin-stimulated lipogenesis was diminished by ginsenosides Rg1 and Rc but not by ginsenoside Rb2.

Adipose Tissue↗
PubMed1986

Insulin-like molecules in Momordica charantia seeds.

Decorticated Momordica charantia seeds were extracted and processed by a method which was developed originally for the purification of insect and annelid insulins. Essentially, the method entailed HCl--ethanol extraction, neutralization with NH4OH, gel filtration on Sephadex G-50, ion exchange chromatography on CM Sepharose CL-6B and desalting on Sephadex G-10. Of the seven fractions collected, three fractions were obtained with antilipolytic and lipogenic activities in isolated adipocytes and one fraction with only lipogenic activity. The data indicate that molecules with insulin-like bioactivity are present in Momordica charantia seeds.

Adipose Tissue↗
PubMed1986

Chemical and biological characterization of the galactose binding lectins from Trichosanthes kirilowii root tubers.

Three galactose binding isolectins have been isolated from Trichosanthes kirilowii root tubers. Two of the isolectins, TK-I and TK-II, are similar in many aspects including molecular weight, amino acid composition, NH2-terminal amino acid residue, blood group and carbohydrate specificities, immunodiffusion and immunoelectrophoretic behavior, hemagglutinating and insulinomimetic activities, and in possessing subunits with different molecular weights. Compared to TK-I and TK-II, lectin TK-III has a larger molecular weight, subunits with the same molecular weight, a single and distinctive NH2-terminal amino acid residue, a different isoelectric point and lower hemagglutinating activity. The three lectins share common antigenic determinants in their structures. beta-Linked terminal oligosaccharides containing D-galactose inhibit hemagglutination induced by the lectins with a higher potency than alpha-linked oligosaccharides. The lectins are non-mitogenic and did not inhibit the concanavalin-A induced mitogenic response of lymphocytes.

Adipose Tissue↗
PubMed1986

Isolation and characterization of a galactose binding lectin with insulinomimetic activities. From the seeds of the bitter gourd Momordica charantia (Family Cucurbitaceae).

A galactose binding lectin was isolated from the seeds of the bitter gourd Momordica charantia by delipidation with petroleum ether, extraction with phosphate buffered saline, ammonium sulfate precipitation and affinity chromatography on lactogel. The lectin had a molecular weight of 124,000 and approximately 5% carbohydrate content. The molecular weights of the individual subunits were 37,000, 35,000 and 33,000. The lectin exhibited potent hemagglutinating activity. In addition, it demonstrated antilipolytic and lipogenic activities in isolated rat adipocytes although it did not possess intrinsic lipolytic activity. The antilipolytic activity was susceptible to destruction by heat, trypsin, chymotrypsin, glutathione and galactose, indicating that the integrity of the protein moiety, the disulfide linkages, and galactose, which is the sugar specifically bound by the lectin, all play an important role in interaction with the adipocyte leading to an expression of this insulin-like activity.

Adipose Tissue↗
PubMed1986

Effects of pineal indoles and arginine vasotocin on lipolysis and lipogenesis in isolated adipocytes.

The effects of arginine vasotocin and the pineal indoles melatonin, serotonin, N-acetylserotonin, hydroxytryptophol, methoxytryptophol, hydroxyindoleacetic acid, methoxyindoleacetic acid, and methoxytryptamine on lipolysis and lipogenesis in isolated adipocytes were studied. Basal lipolysis was inhibited by all the indoles tested at a dose of 1 mumole except hydroxytryptophol. Methoxytryptamine and serotonin inhibited hormone-induced lipolysis in a dose-dependent manner and exhibited the highest antilipolytic activity in isolated rat, rabbit, and hamster adipocytes. However, their antilipolytic activity could not be overcome by increasing the dose of the lipolytic hormone. Dibutyryl cyclic AMP-induced lipolysis was also inhibited. All the pineal indoles tested were capable of suppressing basal and insulin-stimulated lipogenesis in the dose range 0.33-3 nmole. At lower doses there was no effect. Arginine vasotocin at a dose of 25 nmole significantly augmented basal lipogenesis.

Adipose Tissue↗
PubMed1986

A steryl glycoside fraction from Momordica charantia seeds with an inhibitory action on lipid metabolism in vitro.

A saponin fraction was isolated from Momordica charantia seeds by delipidation, saline extraction, ammonium sulfate precipitation, and extraction of the resulting supernatant with n-butanol. Thin-layer chromatography, in the upper phase of the n-butanol--ethyl acetate--water (4:1:5, by volume) system on plastic sheets coated with silica gel 60 F254, revealed the presence of a single spot after spraying with 10% sulfuric acid. The lack of contamination of the saponin preparation with proteins was judged by the absence of protein bands in sodium dodecyl sulfate--polyacrylamide gel electrophoresis, agarose electrophoresis and agarose diffusion, and by the absence of an absorption maximum around 278 nm. The saponin acted as a noncompetitive inhibitor of corticotropin, glucagon, and epinephrine in lipolysis in isolated rat adipocytes, and it also antagonized dibutyryl cAMP induced lipolysis. The antilipolytic activity was resistant to heat, trypsin, chymotrypsin, pronase, and glutathione, in keeping with the chemical nature of saponin. Incorporation of [3-3H]glucose into lipid was inhibited. Adipocyte viability and ATP content were not affected by the saponin, suggesting that its inhibitory effects on lipolysis and lipogenesis were not due to an adverse effect on cell viability.

Adipose Tissue↗
PubMed1985

Horseshoe crab (Limulus polyphemus) lectin but not garden snail (Helix pomatia) lectin elicits insulin-like activities in vitro.

Lectins from the horseshoe crab (Limulus polyphemus) and the garden snail (Helix pomatia) were tested for insulinomimetic activities in isolated rat epididymal adipocytes. The sialic acid binding horseshoe crab lectin suppressed epinephrine-induced lipolysis and augmented lipogenesis from D-[3-3H]-glucose while the N-acetylgalactosamine binding snail lectin was inactive. The results suggest that the insulin receptor on rat adipocytes contains sialic acid in its carbohydrate moiety but does not possess non-reducing alpha-D-galactopyranosyl or 2-acetamido-2-deoxy-alpha-D-galactopyranosyl end groups.

Adipose Tissue↗
PubMed1985

Epidermal and nerve growth factors manifest antilipolytic and lipogenic activities in isolated rat adipocytes.

The effects of epidermal growth factor (EGF) and nerve growth factor (NGF) from mouse submaxillary glands on lipolysis and lipogenesis in isolated rat adipocytes were studied. EGF and NGF at nanomolar concentrations augmented basal lipogenesis. The lipogenic responses to EGF and NGF were additive with a submaximal response induced by insulin but not with that of a maximal response to insulin, indicating a similarity in the mechanisms of action of EGF, NGF and insulin. EGF and NGF also inhibited epinephrine-induced lipolysis. The antilipolytic and lipogenic activities of EGF and NGF were considerably less potent by concentration than those of insulin.

Adipose Tissue↗
PubMed1985

Effect of Trichosanthes kirilowii lectin on lipolysis and lipogenesis in isolated rat and hamster adipocytes.

The galactose-binding lectin from the Chinese herb Trichosanthes kirilowii (Tianhuafen) stimulated the incorporation of D-[3-3H]glucose into lipids in isolated rat epididymal adipocytes. The lectin, however, did not inhibit lipolysis induced by either epinephrine or corticotropin in these adipocytes. Similarly, it did not suppress corticotropin-induced lipolysis in isolated hamster adipocytes. At a dose that did not stimulate lipolysis on its own, the lectin slightly potentiated the lipolytic effects of corticotropin and epinephrine. These findings are discussed in relation to previous observations on other galactose-binding lectins.

Adipose Tissue↗
PubMed1985

Screening of Trichosanthes kirilowii, Momordica charantia and Cucurbita maxima (family Cucurbitaceae) for compounds with antilipolytic activity.

Saline extracts of Trichosanthes kirilowii root tubers and Momordica charantia seeds were subjected to differential acetone fractionation. The fraction that precipitated after addition of 0.8 vol. acetone was designated API, the fraction that precipitated after addition of another 1.2 vol. acetone was designated APII, and the fraction that precipitated after addition of another volume acetone was designated APIII. API, APII and APIII are fractions enriched with lectins, abortifacient proteins and saponins, respectively. T. kirilowii API and APII, and the purified lectin and abortifacient protein (alpha-trichosanthin), were devoid of any significant antilipolytic activity. M. charantia seed API and APIII inhibited hormone-induced lipolysis; the purified lectin and saponin similarly possessed antilipolytic activity. M. charantia seed APII and abortifacient proteins (alpha- and beta- momorcharins), however, lacked such activity. The acid acetone powder of M. charantia seeds and the acetone powder of M. charantia fruits also exhibited antilipolytic activity. However, the acetone powder of Cucurbita maxima fruits and seeds possessed neither antilipolytic nor lipogenic activity. The results indicated that M. charantia fruits and seeds contained components that resembled insulin in inhibiting hormone-induced lipolysis, and that compounds with antilipolytic activity were probably absent from T. kirilowii root tubers and C. maxima fruits and seeds.

Abortifacient Agents, Nonsteroidal↗
PubMed1985

Byssinosis in Hong Kong.

After a report in 1980 of the first three diagnosed locally cases and a preliminary epidemiological investigation that found little evidence of the disease, a survey was aimed at determining the prevalence of byssinosis in Hong Kong. Some 1776 workers in six cotton mills were studied using the standard MRC questionnaire and portable spirometers. Only 48 (2.7%) of the mill workers had symptoms acceptable for a diagnosis of byssinosis. The pattern of relation to dust exposure levels was similar to findings in other countries: blowing and carding process operatives had twice the prevalence rate of the spinners. Another 178 workers (10%) had symptoms of chest tightness or breathlessness or both that were not related to the first exposure after a break and therefore did not fit the standard diagnosis. Some 257 workers (14.5%) had chronic obstructive airflow disease but only 12 (4.7%) had chronic bronchitis. Job mobility had self selection of sensitive cases out of cotton dust exposure seem the most likely explanations for the low prevalence. The significance of non-specific lung ailments needs further assessment to elucidate the possible connection with cotton dust exposure.

Adult↗
PubMed1985

Mental health and work stress in office workers in Hong Kong.

Mental health and work stress among 653 office workers in Hong Kong were studied using Goldberg's 12-item general health questionnaire (GHQ), with slight modification, and McLean's self-assessment scheme in a self-administered questionnaire. It was found that more respondents reported symptoms in the six negative than in the six positive GHQ items. The proportions reporting problems in McLean's areas of coping, context, and stressors were 20.9%, 47.7%, and 14.8%, respectively. Females reported more problems in both context and coping than did males, but no difference was found between them for stressors. Multiple regression analysis revealed a strong association (r = .63) between mental ill health and McLean's three factors, with coping the most important factor for females, context the most important for males, and stressors the least important for both sexes in predicting mental ill health.

Adult↗
PubMed1981

Comparison of the metabolic and antihypertensive properties of tienilic acid and hydrochlorothiazide.

Tienilic acid (2,3-dichloro-4-(2-thienylcarbonyl) phenoxyacetic acid) is a new diuretic with uricosuric properties. Eighteen patients, aged between 37 and 67 years, with moderate arterial hypertension underwent a double-blind, within-patient, crossover study to compare the effects of tienilic acid (TNCF) and hydrochlorothiazide (HCTZ) on blood pressure, renal function, serum levels of uric acid and electrolytes, and liver function. Blood pressure was lowered similarly by TNCF and HCTZ. The prime advantage of TCNF over HCTZ was its profound hypouricaemic effect. Despite the possibility of hepatotoxicity of TNCF, it may still have a place in the treatment of hypertensive hyperuricaemic patients when the mechanism of hepatotoxicity of TNCF is elucidated.

Adult↗