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Biomedical subjects

Y C Chan

Publications and source records attributed to Y C Chan.

At least 73 records · Page 4Linked to original sources
PubMed1997

Dietary, anthropometric, hematological and biochemical assessment of the nutritional status of centenarians and elderly people in Okinawa, Japan.

OBJECTIVE: The population of old people has increased and nutritional disorders are common among them. The assessment of nutritional status and dietary intakes of this population is necessary in order to improve their nutritional status and reduce risk to infection and mortality. In the present study, data on the nutritional status of healthy elderly and centenarians is provided. SUBJECTS: Participants were free-living healthy volunteers (39 centenarians; 11 male and 28 female and 44 elderly in their 70s; 13 male and 31 female). METHODS: Their nutritional status was assessed by anthropometric measurements, hematological and biochemical variables. Activities of daily living (ADL) of 11 items were scored depending upon their activities with a maximum score of 5.0. Dietary survey by food recording was done for 2 days and food models were used to obtain the best estimate of food intake. Energy and nutrient intakes were compared with Japanese recommended dietary allowances (RDAs). RESULTS: The elderly had complete independence of physical activities, good sensory function and cognitive abilities. The physical activities of male centenarians were between the category of completely independent and independent but slow. In female centenarian participants, their physical activities were independent but slow or independent with difficulty. The functions of auditory acuity and eyesight of the centenarians were poor but their cognitive abilities were still good. The elderly subjects had short stature whereas their body weight and body mass index (BMI) were not low, especially among the women, compelling female elderly to reduce their food intake to control the weight. Energy intake of female centenarians was low. The ADL in the female centenarians was positively related to energy, suggesting that the low energy intake of the female centenarians was mainly due to their low ADL. Anthropometric, hematological and biochemical variables of the centenarians were lower or near the lower reference limit except serum lipids. All the hematological and biochemical variables were statistically lower (p < 0.05) in the centenarians than in the elderly particularly for females with some minor exceptions. CONCLUSION: The results of the present study showed that the nutritional status assessed by ADL and anthropometric, hematological and biochemical parameters was poor in the centenarian subjects but was maintained in the elderly subjects except height and that the diet was not the major factor of their problems in the nutritional status.

Activities of Daily Living↗
PubMed1997

Expression of the dengue virus structural proteins in Pichia pastoris leads to the generation of virus-like particles.

We have expressed cDNA encoding the dengue virus structural proteins in Pichia pastoris by chromosomal integration of an expression cassette containing the dengue virus structural genes (CprME). The yeast recombinant E protein migrated during SDS-PAGE as a 65 kDa protein when analysed by Western blotting and radioimmunoprecipitation, which is the expected molecular mass for correctly processed and glycosylated E protein. Treatment with endoglycosidases showed that the recombinant E protein was modified by the addition of short mannose chains. The E protein migrated with a buoyant density of 1.13 g/cm3 when analysed using sucrose density gradient centrifugation. Spherical structures with an average diameter of 30 nm, whose morphology resembles dengue virions, were observed in the purified fractions using transmission electron microscopy. Furthermore, the virus-like particles were immunogenic in animals and were able to induce neutralizing antibodies. This is the first report that expression of the structural genes of a flavivirus in yeast is able to generate particulate structures that resemble virions.

Centrifugation, Density Gradient↗
PubMed1997

Automated type specific ELISA probe detection of amplified NS3 gene products of dengue viruses.

AIM: To apply an automated system of nucleic acid hybridisation coupled with the enzyme linked immunosorbent assay (ELISA) for the type specific detection of amplification products of dengue viruses. METHODS: Non-structural 3 (NS3) gene targets of reference strains of all four dengue and other flaviviruses, as well as dengue patient viraemic sera, were subjected to reverse transcription and polymerase chain reaction using consensus and dengue type specific primers and digoxigenin-11-dUTP label incorporation. The amplification products were detected by biotinylated type specific primers which served as ELISA capture probes bound to streptavidin coated tubes. RESULTS: Significantly high spectrophotometric absorbance readings were obtained by hybridisation of the consensus and seminested amplification products of all four dengue viruses with their respective capture probes. In contrast, extremely low absorbances were observed for consensus products of Japanese encephalitis, yellow fever, and Kunjin viruses, which served as negative controls. These ELISA data correlated well with agarose gel electrophoresis of dengue type specific amplified products of diagnostic sizes. CONCLUSIONS: The combination of in vitro amplification and antibody based detection offers rapid, type specific, high throughput, and gel-free detection of amplified products of dengue viruses.

Dengue↗
PubMed1997

Nutritional status of centenarians assessed by activity and anthropometric, hematological and biochemical characteristics.

For the maintenance of good health of very old people such as centenarians, nutrition is very important. However, the information on their nutritional status is very limited. In this study, we evaluated the nutritional status of centenarians by comparison with elderly in their 70 s and young adults. Volunteer subjects were comprised of 71 centenarians (51 females, 20 males) who were not bed ridden, 84 elderly in their 70 s (51 females, 33 males) who had no specific health problems and 27 healthy young adults in their 20 s (17 females, 10 males). We compared 11 items of the activities of daily living (ADL), height, weight, hematological (hemoglobin, hematocrit and red blood cell count) and biochemical [total protein, albumin, total-, HDL-, LDL- and VLDL-cholesterols, triglycerides, glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and creatinine] variables among the three age groups. Since the atrophy of muscle is more severe than the atrophies of other tissues in the elderly, we studied the muscle protein breakdown using plasma 3-methylhistidine (3-MH) as a marker. The results of all indices except serum lipids, GOT and GPT, were lower in the centenarians than in the subjects in their 20 s (p < 0.05) and were lower than the lower reference limits. Most of the results of the elderly in their 70s were within the reference intervals. However, as compared to the young subjects, they had: 1) normal ADL; 2) shorter height; 3) heavier weight in females and lighter weight in males; 4) lower total protein and albumin levels and albumin/globulin (A/G) ratios; and 5) higher total- and LDL-cholesterol levels in females and HDL-cholesterol levels in males (p < 0.05). The plasma 3-MH concentration was higher in the centenarian group than in the young and elderly groups (p < 0.05). However, serum creatinine concentrations also tended to be high in the group, suggesting that a high 3-MH concentration did not indicate accelerated muscle protein breakdown but rather poor kidney functions. The results of this study show that the centenarians had shrunken stature, low hematological values and poor protein nutrition but rather normal lipid nutrition, however the elderly subjects in their 70s could still maintain most nutritional parameters in relatively normal condition.

Activities of Daily Living↗
PubMed1997

Continuous quality improvement: a survey of American and Canadian healthcare executives.

The continuous quality improvement (CQI) movement, while experiencing great popularity years ago, has been declining in interest across other industries. This article studied American and Canadian hospital executives who have embraced the concept of CQI and will continue to be committed to CQI efforts in the future. Executives of CQI hospitals strongly believe that CQI is not a fad and is essential to their organizations' survival. The majority of the hospital executives in the sample have a good understanding of CQI. The drive to provide quality service to both internal and external customers is the primary motivation for being involved with CQI. Some unsuccessful CQI efforts can be attributed to a lack of CQI skills, poor planning, and insufficient staffing. Close to 90 percent of the respondents expected their involvement with CQI to increase significantly in the future. This result implies that CQI is still being considered and will maintain its role as an effective management tool in the healthcare sector.

Attitude of Health Personnel↗
PubMed1996

Recombinant dengue type 1 virus NS5 protein expressed in Escherichia coli exhibits RNA-dependent RNA polymerase activity.

The complete nonstructural NS5 gene of dengue type 1 virus, Singapore strain S275/90 (D1-S275/90) was expressed in Escherichia coli as a glutathione S-transferase (GST) fusion protein (126 kDa). The GST-NS5 fusion protein was purified and the recombinant NS5 protein released from the fusion protein by thrombin cleavage. The recombinant NS5 had a predicted molecular weight of 100 kDa and reacted with antiserum against D1-S275/90 virus in Western blot analysis. The purified recombinant NS5 protein possessed RNA-dependent RNA polymerase activity which was inhibited (>99%) by antibodies against the recombinant NS5 protein. The polymerase product was shown to be a negative-stranded RNA molecule, of template size, which forms a double-stranded complex with the template RNA.

Animals↗
PubMed1996

A nucleoside-nucleotide mixture and its components increase lymphoproliferative and delayed hypersensitivity responses in mice.

We studied the effect of individual components of a nucleoside-nucleotide mixture on T cell-mediated immunity in BALB/c and DBA/2 mice. Mice were fed for 4 wk a nucleotide-free 20% casein diet (control) or this diet supplemented with 3 mol/kg of one of the following; inosine, guanosine monophosphate, uridine, cytidine, thymidine, or a mixture of these. In both strains of mice, popliteal lymph node immunoproliferative response to alloantigeneic (C57BL/6 splenic cells) challenge in mice fed the mixture and guanosine monophosphate was greater (P < 0.05) than in the mice fed the control diet. BALB/c mice fed inosine, uridine, and thymidine also showed greater (P < 0.05) responses compared with control fed mice. In the sheep red blood cells challenge assay, foot pad weight-gain in both strains of mice fed the mixture and the individual components supplemented diets was greater (P < 0.05) than in those fed the control diet. In both strains of mice, interleukin-2 secretion by popliteal lymph node lymphocytes in mice fed the mixture and thymidine was higher (P < 0.05) compared with the rest of the groups except BALB/c mice fed cytidine. Significantly higher than control secretions of interferon-gamma were observed only in BALB/c mice fed inosine, thymidine and the mixture. We conclude that mice fed the nucleoside-nucleotide mixture and the individual components of the mixture had greater responses in the T cell-mediated immune functions studied and that the responses in mice fed the mixture were not different from those in mice fed the individual components.

Animals↗
PubMed1996

Comparative effects of dietary nucleoside-nucleotide mixture and its components on endotoxin induced bacterial translocation and small intestinal injury in protein deficient mice.

BACKGROUND: Nucleoside-nucleotide mixture has been shown to improve gut morphology and reduce the incidence of bacterial translocation in protein deficient mice. AIMS: To compare the reparative effect of nucleoside-nucleotide mixture and their individual components on maintenance of gut integrity and bacterial translocation based on their differential metabolism and utilisation. METHODS: ICR (CD-1) mice were randomised into eight groups of 10 animals each and fed 20% casein diet (control), protein free diet, or protein free diet supplemented with 3 M cytidine, uridine, thymidine, inosine, guanosine monophosphate, or nucleoside-nucleotide mixture for four weeks. On the fourth week, each mouse was injected lipopolysaccharide intraperitoneally (50 micrograms/500 microliters) and the incidence of bacterial translocation, caecal bacterial populations, and the ileal histology, noted 48 hours later. RESULTS: The death rate in the control group was 40% compared with 10% in the nucleoside-nucleotide mixture and 20% each in the individual components groups, respectively. Bacterial translocation to the mesenteric lymph node did occur in 100% of the surviving mice fed the control diet in comparison with 44% (nucleoside-nucleotide), 50% (cytidine), 75% (thymidine), 75% (uridine), 63% (inosine), and 63% (guanosine monophosphate). Histologically, the damage to the gut was more distinct in the protein free diet group. Villous height, crypt depth, and wall thickness in the nucleoside-nucleotide mixture group mean (SEM) (5.01 (0.34); 0.87 (0.14); 0.33 (0.10)), were respectively, higher compared with the protein free diet (3.34 (0.34); 0.61 (0.03); 0.18 (0.04)) group. In the cytidine group, crypt depth (0.86) (0.08)), and wall thickness (0.30 (0.002)) were higher. The same measurements in the components groups tended to be higher than the protein free diet group. Caecal bacterial populations were, however, similar in all groups. CONCLUSIONS: These results suggest that dietary nucleosides and nucleotides are essential nutrients for intestinal repair; nucleotides or cytidine provide a better response.

Animals↗
PubMed1996

Energy and nutrient intakes of Okinawan centenarians.

Energy and nutrient requirements of younger people have been well studied, unlike that of centenarians. The average life span of the Japanese is the longest in the world, and the population of the very aged is rapidly growing. In addition, the average life span of Okinawan people is the longest in all of Japan. Their food habits also differ from other parts of Japan. To obtain basic dietary information, we surveyed 21 centenarians in Okinawa (17 women and 4 men). The dietary survey was done by one 24 h recall method, as was done for centenarians living throughout Japan (3). The energy intake of the Okinawan centenarians living at home was about 1,100 kcal/day for both sexes, which was similar to that of centenarians throughout Japan. Energy, some nutrient intakes and food consumption pattern (in terms of food groups) were different from those of the centenarians throughout Japan. We also measured their heights, weights, hematological values and activities of daily living (ADL). Comparison between the nutrient intakes and the recommended dietary allowances (RDAs) estimated for the centenarians showed that the estimated RDA of energy for the Okinawan centenarians might be less than their actual intakes.

Activities of Daily Living↗
PubMed1996

Effect of egg white on serum cholesterol concentration in young women.

In a previous study we observed favorable effects of egg white on serum lipids in rats and mice. The present study was designed to elucidate these effects in 24 female university students with moderate hypercholesterolemia. About 30% of total protein was supplied with egg white, tofu or cheese. The experiment was conducted for a complete menstruation cycle of each subject. Lipid intake was about 30% of total energy intake. The energy intake of each subject was constant throughout the experiment. Body weight was measured every morning. Daily activity was measured by a pedometer. Blood was withdrawn after an overnight fast on the first, 15th and last days and serum lipids were measured. Body weight was measured every morning. Daily activity was measured by a pedometer. Blood was withdrawn after an overnight fast on the first, 15th and last days and serum lipids were measured. Body weight and daily activity were maintained in all the groups throughout the experiment. The egg white group showed a similar decrease in the total cholesterol (Total-C) concentration but a greater increase of high-density lipoprotein cholesterol (HDL-C) concentration as compared to the tofu group and a greater decrease in Total-C and low-density lipoprotein cholesterol (LDL-C) concentrations and a greater increase in the HDL-C concentration as compared to the cheese group (p < 0.05). The results indicate the favorable effects of egg white in the control of hypercholesterolemia.

Adult↗
PubMed1996

A clinically viable index for quantifying denture plaque.

A denture plaque index using the dye disclosing method was evaluated in 24 patients with Type II denture stomatitis and 17 control subjects with healthy palatal mucosa. Patients with denture stomatitis had statistically significantly higher plaque scores than did controls, indicating a quantitative increase in denture plaque in patients with denture stomatitis. When this plaque index was tested by two examiners for intraexaminer and interexaminer reproducibility, it yielded a 92% to 96% reproducibility. The plaque index used in this study seems to satisfy the criteria for an ideal clinical index: It is simple, reliable, reproducible, and economical and can be carried out in the shortest possible time in a clinical setting.

Dental Plaque↗
PubMed1996

A severe case of hemorrhagic fever with renal syndrome in Singapore.

The incidence of human hantavirus infection in Singapore is low. Hitherto, only 2 cases of hemorrhagic fever with renal syndrome (HFRS) have been reported. A third case is reported here of a ragman who had the classical manifestations of HFRS, confirmed by serology. In addition, his condition was complicated by liver dysfunction and neurological disturbance. After a protracted stay, the patient was finally discharged from hospital 5 months after the onset of his severe illness.

Aged↗
PubMed1995

Semi-nested PCR using NS3 primers for the detection and typing of dengue viruses in clinical serum specimens.

BACKGROUND: More rapid, specific and sensitive tests for the laboratory diagnosis of dengue virus infections are needed. OBJECTIVE: To develop a semi-nested polymerase chain reaction (PCR) assay based on primers within the NS3 gene for the simultaneous detection and typing of dengue viruses in human sera. STUDY DESIGN: A first round of single-step reverse transcription-polymerase chain reaction (RT-PCR) was carried out with a pair of consensus primers, followed by a second round of semi-nested amplification using the upstream consensus primer and four type-specific down-stream primers. The sensitivity and specificity of the semi-nested PCR assay were determined using plaque- or TCID(50)-titrated virus-infected tissue culture fluid, and total RNA extracted from C6/36 cells infected with dengue and other flaviviruses, respectively. A retrospective study was performed on acute sera from thirteen patients with dengue (confirmed by virus isolation) employing semi-nested PCR in parallel with virus re-isolation and a single-step RT-PCR method for the typing of dengue viruses in human sera. RESULTS: The semi-nested PCR assay could detect up to 1 pfu of dengue virus, but not other flaviviruses. The semi-nested PCR and single-step RT-PCR assays correctly typed dengue viruses in twelve and five sera, respectively, whereas none of the sera was positive by virus re-isolation. CONCLUSIONS: This semi-nested PCR assay is a sensitive and specific tool for the detection and typing of dengue viruses from viremic human sera.

Journal Article↗
PubMed1995

Adult dengue deaths in Singapore.

BACKGROUND: Dengue haemorrhagic fever (DHF) is a leading cause of hospitalization of children in Southeast Asia and regarded mainly as a problem of childhood. In Singapore, however, both dengue fever (DF) and DHF now occur most frequently in those aged 16-25 years and case fatality rates are higher among adults than children. OBJECTIVE: To describe adults who died from DHF in Singapore. STUDY DESIGN: The clinical, laboratory and, where performed, autopsy records of adults reported to the Ministry of the Environment to have died from DHF were reviewed. RESULTS: Four of 10 adults had clinical, serological and/or virological evidence of acute dengue virus infection. All 4 patients, who were between 27 and 58 years old, had dengue IgM antibodies. Two of them had elevated dengue IgG antibodies consistent with a recent infection. Dengue type 2 virus was isolated from one of these two patients who had bled into the lungs, skin, pericardial and pleural surfaces and succumbed to shock. The other patient had no evidence of overt bleeding. A third patient, who suffered massive intractable retroperitoneal haemorrhage and shock, seroconverted in the haemagglutination inhibition test for dengue antibodies. The fourth patient had bleeding into her skin, urinary and gastrointestinal tracts, acute pulmonary oedema, ascites and hypotension. Her stillborn baby also had ascites. CONCLUSION: Deaths from DHF are not mainly a childhood occurrence. Adults do die from severe DHF, whether the infection be primary or secondary.

Journal Article↗
PubMed1995

Serum antibodies to Trichomonas vaginalis in invasive cervical cancer patients.

OBJECTIVE: To evaluate, by seroepidemiology, the possible role of the sexually-transmitted flagellate, Trichomonas vaginalis, in invasive cervical cancer. SUBJECTS AND METHOD: Sera from 121 invasive cervical cancer patients and 242 random age-matched female controls. Antibodies to T. vaginalis were detected by the western blot technique. RESULTS: Antibodies to T. vaginalis were detected in the sera of 41.3% (50/121) of invasive cervical cancer patients compared with only 5.0% (12/242) of female controls. All the reactive sera reacted strongly with the immunogenic surface membrane proteins of T. vaginalis of molecular weights of about 92 and 115 kDa, with variable reactivity to other immunogenic proteins of T. vaginalis. CONCLUSION: The significantly increased relative risk, RR = 3.42 (95% CI = 1.73-6.78), is comparable to the RRs derived in seroepidemiological studies of human papillomavirus, suggesting that T. vaginalis may be even more closely associated with invasive cervical cancer than previously realized.

Adult↗
PubMed1995

Comparison of Pseudomonas pseudomallei from humans, animals, soil and water by restriction endonuclease analysis.

Pseudomonas pseudomallei isolates from 62 human, 17 animal, 3 soil and 3 water samples were examined by genomic DNA digestion with PstI. Five major (RE I, II, III, IV, V) reproducible restriction patterns were observed, with most (56/62) of the human isolates displaying RE I (30/62), II (5/62), III (15/62), IV (4/62), V (2/62), and the animal (16/17), soil (2/3), water (3/3) isolates showing predominantly RE II profiles. Six human and one soil isolates showed patterns different from those of RE I to V. Restriction endonuclease analysis may be applied in epidemiological studies of melioidosis.

Animals↗
PubMed1994

Parenting stress and social support of mothers who physically abuse their children in Hong Kong.

Thirty-seven identified abusive mothers were matched on demographic and socioeconomic parameters with a known nonabusive comparison sample in order to examine the role of parenting stress and maternal social support. The mothers were assessed using a personal (demographic) questionnaire, the Parenting Stress Index (PSI), and the Maternal Support Index (MSSI). Demographic data showed that the two groups were comparable on all variables except abusive mothers had significantly more children (p = .01). Abusive mothers showed significantly more stress on total PSI scores (p = .005), as well as in all three of the subjects: Child Domain (p = .007) Parent Domain (p = .02), and Life Stress (p = .016). Abusive mothers scored lower in all seven items on the MSSI. The difference was significant on the MSSI as a whole (p = .007) and on four subsets: number of people to count on in time of need (p = .02), perceived neighborhood support (p = .04), satisfaction with spousal relationship (p = .01), and degree of community involvement (p = .03). The greatest percentage (74.32%) of correct predictions of child abuse was achieved by combining the number of children, the Life Stress Scale and the MSSI. Implications for future research are discussed.

Adult↗