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W Mak

Publications and source records attributed to W Mak.

42 records · Page 3Linked to original sources
PubMed1998

Signal transduction pathways involved in enterohemorrhagic Escherichia coli-induced alterations in T84 epithelial permeability.

Enterohemorrhagic Escherichia coli (EHEC) infection is associated with watery diarrhea and can lead to complications, including hemorrhagic colitis and the hemolytic-uremic syndrome. The mechanisms by which these organisms produce diarrheal disease remain to be elucidated. Changes in T84 epithelial cell electrophysiology were examined following EHEC infection. T84 cell monolayers infected with EHEC O157:H7 displayed a time-dependent decrease in transepithelial resistance. Increases in the transepithelial flux of both [3H]mannitol and 51Cr-EDTA accompanied the EHEC-induced decreases in T84 resistance. Altered barrier function induced by EHEC occurred at the level of the tight junction since immunofluorescent staining of the tight-junction-associated protein ZO-1 was disrupted when examined by confocal microscopy. Decreased resistance induced by EHEC involved a protein kinase C (PKC)-dependent pathway as the highly specific PKC inhibitor, CGP41251, abrogated the EHEC-induced drop in resistance. PKC activity was also increased in T84 cells infected with EHEC. Calmodulin and myosin light chain kinase played a role in EHEC-induced resistance changes as inhibition of these effector molecules partially reversed the effects of EHEC on barrier function. These studies demonstrate that intracellular signal transduction pathways activated following EHEC infection link the increases in T84 epithelial permeability induced by this pathogen.

Calmodulin↗
PubMed1998

Tuberculosis meningitis in Hong Kong: experience in a regional hospital.

Tuberculous meningitis (TBM) remains common in Hong Kong. From January 1996 to June 1997, 11 adult patients with TBM presented to Queen Mary Hospital, a regional hospital in Hong Kong. The annual incidence of TBM was estimated at 1.8 per 100,000 population. Nine patients were local Chinese, and only one patient had the acquired immune-deficiency syndrome (AIDS). In contrast to the classical presentation as a chronic indolent disease, our patients presented acutely: the mean duration from onset of symptoms to presentation was 4.8 days (range 0-10). The most common presenting symptoms were headache (64%), fever (46%), or both (36%), with focal deficits occurring in 64% of patients. Cerebrospinal fluid (CSF) culture and polymerase chain reaction (PCR) were positive in 30% and 29% of cases. Mean CSF cell count, protein and glucose levels were 340 x 10(6)/L, 267 mg/dL, and 2.3 mmol/L, respectively. Extra-neural tuberculosis occurred in 46% of cases. All patients survived and responded to treatment. Drug-induced hepatotoxicity was common; 64% of patients developed biochemical hepatitis.

Adult↗
PubMed1986

Disparate uptake of 99mTcO4- and 125I- in thyroid cells in culture.

Pertechnetate (99mTcO4-) is a large anion that is thought to be trapped but not organified by the thyroid. In order to determine its usefulness in discriminating trapping from organification in thyroid cell culture, the uptake of 99mTcO4- has been compared to that of 125I- both in sheep thyroid cells and in FRTL5 cells, a functional rat thyroid cell line. We found that uptake of both isotopes was dependent on TSH or agents that raised intracellular cAMP levels and was displaceable with iodide in both cell types. However in rat cell line 99mTcO4- uptake was up to eight-fold higher than 125I- uptake, and 99mTcO4- but not 125I- uptake was doubled by methimazole treatment. A considerable proportion of 99mTcO4- but not 125I- taken up by the FRTL5 cell but not the sheep cells was precipitable with TCA. This proportion was increased by methimazole treatment. We also found marked differences in sensitivity to ouabain between the two cell types. These results illustrate the differences between species in 125I- and 99mTcO4- transport and support the concerns expressed by Socolow and Ingbar (1967) in using 99mTcO4- as a direct and precise indicator of iodide transport activity.

Animals↗
PubMedDate not supplied

Knowledge of stroke in Hong Kong Chinese.

A random telephone survey on knowledge of stroke was conducted in 1, 238 Hong Kong Chinese. Most respondents realized that effective treatment was available, that stroke was preventable and that it could be fatal or disabling. Sudden unilateral limb weakness, sudden speech and language disturbances, and sudden vertigo and clumsiness were better recognized than other warning symptoms of stroke. A slightly better recognition of symptoms of stroke was seen in those with a belief of knowing about stroke, providing a correct description of stroke, those with a positive household history of stroke and those with a better knowledge of potential risk factors. Most respondents would choose desirable actions if stroke was suspected in their family members or themselves. Friends and relatives, newspapers and magazines, and mass media provided the major sources of their knowledge.

Adolescent↗