Search PubMed⌕ Search

Biomedical subjects

M K Lai

Publications and source records attributed to M K Lai.

At least 19 recordsLinked to original sources
PubMed2006

Latent structure of the Test of Everyday Attention in a non-clinical Chinese sample.

The validity and clinical viability of Posner and Petersen's (1999) 3-factor model of attention was tested through a confirmatory factor analysis of attentional performance (Test of Everyday Attention [Robertson, I. H., Ward, T., Ridgeway, V., & Nimmo-Smith, I. (1996). The structure of normal human attention: The Test of Everyday Attention. Journal of the International Neuropsychological Society, 2, 525-534]) in a sample of 133 Chinese participants. This study served both as a cross-cultural replication of the clinical implementation of this leading theoretical model of attention, and as a more stringent test of the validity of the hypothesized attentional processes underlying human cognitive control. The results support the validity of a 3-factor model of attention consistent with that proposed by Posner and Petersen (selective attention, sustained attention, and attentional switching/control), and demonstrate that clinical assessment of neuroanatomically-distinct attentional processes using simulated real life activities is possible.

Activities of Daily Living↗
PubMed2006

Latent structure of the Test of Everyday Attention: convergent evidence from patients with traumatic brain injury.

AIM: The present study aimed to examine the nature of attention distinctions among sub-tests of the Test of Everyday Attention (TEA) underlying the performance of patients with traumatic brain injury (TBI). METHOD: Confirmatory factor analysis was performed among a group of 92 patients with TBI experiencing chronic post-concussive symptoms. Comparisons were made of the fit of the previously identified models based on exploratory factor analysis, comprising three-to-four factors. MAIN OUTCOME: The results indicated that the 3-factor model with a visual selection component, a sustained attention component and a switching component provided an appropriate account of attentional performance than the other two 4-factor models. CONCLUSION: These findings are consistent with those of healthy sample. This study, therefore, provides convergent evidence on the latent structure of the TEA. It is consistent and stable across healthy and clinical populations.

Adult↗
PubMed2005

Diet, vegetarian food and prostate carcinoma among men in Taiwan.

In a case-control study in a veterans hospital in Taiwan, we compared 237 histology-confirmed prostate carcinoma cases with 481 controls, frequency matched by age, for their consumption of vegetarian food, namely soybean products, rice, wheat protein and other vegetables. The multivariable logistic regression analysis showed a significant association with such food (odds ratio (OR)=0.67, 95% confidence interval (CI)=0.47, 0.94). This beneficial effect presented for men with body mass index (BMI) < or =25 kg m(-2) (OR=0.50, 95% CI=0.32, 0.76) but not for men with greater BMI. The OR of prostate carcinoma for men with BMI < or =25 kg m(-2) was 1.74 (95% CI=1.21, 2.51), compared with men with higher BMI (>25 kg m(-2)). Other significant risk factors associated with the disease included higher income (OR=2.40, 95% CI=1.07, 5.42), physical activity (OR=1.75, 95% CI=1.08, 2.83), being married (OR=2.49, 95% CI=1.40, 4.43) and coffee consumption (OR=1.88, 95% CI=1.07, 3.30). Stratified analysis also showed that the consumption of fish/shellfish had an adverse association for men with higher BMI. This study suggests that the intake of the low fat local vegetarian food has a protective effect against prostate carcinoma for thin men in this study population.

Adenocarcinoma↗
PubMed2005

Overweight, obesity, weight-related concerns and behaviours in Hong Kong Chinese children and adolescents.

AIM: To study the prevalence of overweight and obesity, and weight-related concerns and behaviours among overweight, obese and non-overweight children and adolescents. METHODS: We carried out a cross-sectional survey of all Chinese students in primary schools in the Central and Western District of Hong Kong in March 2002. Thirty-one of 32 schools participated, and 5402 boys and 5371 girls aged 8 to 15 y who completed a standardized questionnaire were included. We used the International Obesity Task Force definition (IOTF reference) to define overweight and obesity. RESULTS: The prevalence (95% CI) of overweight was 16.4% (15.7-17.1%) (19.9% in boys, 12.9% in girls), and that of obesity was 7.7% (7.2-8.2%) (10.3% in boys and 5.1% in girls). The combined prevalence of overweight and obesity was similar to that based on the local reference. Overweight children had more concerns about their weight than obese children. They were more likely than obese children to feel fat, wish to be lighter, diet and exercise to lose weight. Although obese children were heavier, they did not make more effort to lose weight than overweight children. CONCLUSIONS: The differences in weight-related concerns and behaviours among overweight, obese and non-overweight children suggested good validity of the IOTF reference and the self-reported data. The differences between overweight and obese children suggested that the two groups had different psychological states and that they needed different weight management programmes and other intervention strategies.

Adolescent↗
PubMed2004

Loss of serotonin 5-HT2A receptors in the postmortem temporal cortex correlates with rate of cognitive decline in Alzheimer's disease.

RATIONALE: Previous studies have demonstrated reductions of serotonin 5-HT 2A receptors in the neocortex of Alzheimer's disease (AD) patients. However, it is unclear whether such losses play a role in the cognitive decline of AD. OBJECTIVES: To correlate neocortical 5-HT 2A receptor alterations with cognitive decline in AD. METHODS: Postmortem frontal and temporal cortical 5-HT 2A receptors were measured by [3H]ketanserin binding in aged controls as well as in a cohort of AD patients who had been longitudinally assessed for cognitive decline and behavioral symptoms. RESULTS: 5-HT 2A receptor densities in both regions were reduced in severely demented AD patients compared to age-matched controls. In the temporal cortex, this reduction also correlated with the rate of decline of Mini-Mental State Examination (MMSE) scores. The association between 5-HT 2A receptor loss and cognitive decline was independent of the effects of choline acetyltransferase (ChAT) activity and presence of behavioral symptoms. CONCLUSIONS: Our data suggest that loss of neocortical 5-HT 2A receptors may predict for faster cognitive decline in AD, and point to serotomimetics as potentially useful adjuvants to cholinergic replacement therapies.

Aged↗
PubMed2003

[3H]GR113808 binding to serotonin 5-HT(4) receptors in the postmortem neocortex of Alzheimer disease: a clinicopathological study.

Abnormalities in neural transmission of serotonin (5-HT) may play a role in both cognitive and neuropsychiatric features of Alzheimer disease (AD). We measured 5-HT(4) receptors in the postmortem frontal and temporal cortex of 34 AD subjects and 15 controls by radioligand binding with [3H]GR113808. Receptor binding data was then correlated with prospectively assessed cognitive (Mini-Mental State Examination, MMSE) and behavioral (Present Behavioural Examination, PBE) data. [3H]GR113808 binding affinity (K(D)) and density (B(max)) in AD were unchanged compared to controls in both cortical regions, and did not correlate with MMSE or PBE data. The binding parameters were also not related to disease duration, senile plaque and neurofibrillary tangle counts, and neuroleptic medication. We conclude that unlike other 5-HT receptors, 5-HT(4) receptor binding affinity and density do not seem to be affected in the frontal and temporal cortex in AD and may not have a direct role in the clinical features of the disease.

Aged↗
PubMed2001

Psychosis of Alzheimer's disease is associated with elevated muscarinic M2 binding in the cortex.

OBJECTIVES: Results from recent drug trials suggest a role for the cholinergic system in the manifestation of neuropsychiatric symptoms in AD. To date, the status of muscarinic acetylcholine receptor subtypes in AD in relation to accompanying behavioral disturbances is unknown. This study aimed to measure alterations of muscarinic M(1) and M(2) receptor binding in the frontal and temporal cortex of AD and to correlate the neurochemical findings with clinical features. METHODS: The cognitive and behavioral features of 26 patients with AD were assessed prospectively using standardized tests. Together with 14 matched controls, the status of muscarinic M(1) and M(2) receptors in the postmortem frontal and temporal cortex of these patients were measured by radioligand binding assays and were correlated with clinical data. RESULTS: Compared with controls, M(2) receptor density was reduced only in the frontal cortex of AD, whereas M(1) was unaffected. Within the AD group, the neurochemical variables were not affected by demographic factors, disease severity, or cognition. Instead, M(2) receptor density was increased in the frontal and temporal cortex of patients with AD with psychotic symptoms compared with those without these symptoms. CONCLUSIONS: This study suggests a role for M(2) receptors in the psychosis of AD and may provide the rationale for treatment of behaviorally perturbed patients with AD with cholinomimetics and M(2) antagonists.

Aged↗
PubMed2001

Modified approach of hand-assisted laparoscopic nephroureterectomy for transitional cell carcinoma of the upper urinary tract.

Objectives. To report a modified approach for hand-assisted laparoscopic nephroureterectomy (HALNU).Methods. Seven patients with localized transitional cell carcinoma of the upper urinary tract underwent unilateral HALNU. Patients were placed in a 60 degrees oblique position during the entire procedure. Via a 7-cm Gibson incision on the lesion side, the distal ureterectomy and bladder cuff excision were done by an open method without opening the bladder. Then, with the surgeon's hand inserted into the peritoneal cavity by way of the same wound, HALNU was performed with two to three additional laparoscopic ports. The perioperative parameters were compared with those of 15 cases of conventional open nephroureterectomy.Results. Patients in the HALNU group had significantly less mean blood loss (140 versus 455 mL) and earlier resumption of oral intake (33 versus 61 hours), required fewer narcotics (38 versus 70 mg of morphine sulfate equivalent), and were discharged earlier (7.33 versus 9.1 days), with a faster convalescence to normal activity (3.7 versus 5.6 weeks; all P < 0.05). The total mean surgical time was 3.7 hours for the HALNU group.Conclusions. Our approach used the same incision to both excise the distal ureter and apply the hand-assist device. It also preserved the benefits of the minimal invasiveness of laparoscopic surgery compared with its open counterpart.

Aged↗
PubMed2001

The dilemma of "to-be or not-to-be": needs and expectations of the Taiwanese cadaveric organ donor families during the pre-donation transition.

There has been little study of the Chinese cadaveric donor family's decisions to donate organs within the Chinese cultural framework. A convenience sample of 25 cadaveric donor family members (12 men, 13 women) who gave their consent to donation at National Taiwan University Hospital agreed to participate in this study and completed in-depth interviews. Data were analyzed by a three-steps within-method qualitative triangulation method. The factors influencing the donor family's decisions to donate organs, the needs of donor families, and their expectations of health care providers during the pre-donation transition--the critical period of time between signing a donation and consent to organ harvesting--were examined. The background context and a conceptual framework were further developed to discuss and depict this phenomenon. This project aims to broaden the horizon on organ donation and contribute to the understanding of some of the psychodynamic issues in the Chinese family in Taiwan.

Adult↗
PubMed2001

Paraganglioma manifesting as shock: a case report.

Paraganglioma is a rare neuroendocrine tumor in children that rarely manifests as shock. We describe the case of a 12-year-old girl with paraganglioma who developed impaired cardiac function, pulmonary edema, and shock at the time of admission. Her blood pressure stabilized after intravenous normal saline rescue and dopamine treatment. However, hypertension was noted thereafter. After a series of examinations, paraganglioma was diagnosed and excision of the tumor was performed. After surgery, blood pressure stabilized and her cardiac function had fully recovered at 4 months' follow-up.

Child↗
PubMed2001

Dual effects of ouabain on the regulation of proliferation and apoptosis in human prostatic smooth muscle cells.

PURPOSE: To elucidate the role of ouabain in the pathophysiology of benign prostatic hyperplasia we examined the effects of ouabain on the proliferation and apoptosis of human prostatic smooth muscle cells. MATERIALS AND METHODS: Primary cultures of human prostatic smooth muscle cells were obtained from 7 patients with bladder outlet obstruction caused by benign prostatic enlargement. A cell proliferation study was performed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay method to examine the effects of different concentrations of ouabain and various inhibitors. Western blot analysis was done to determine mitogen activated protein kinase (MAPK) activation. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling reaction method and caspase-3 activity assay were also performed to examine the apoptotic mechanism. RESULTS: Ouabain exhibited a modest but significant proliferative effect in nanomolar concentrations; whereas it induced cell apoptosis at higher concentrations. Ouabain caused rapid activation of p42/44 MAPKs. The proliferative effect of ouabain was completely flattened by W-7 and MAPK kinase (MEK) inhibitor, suggesting the requirement of Ca(2+) mobilization and the involvement of the MEK-p42/44 MAPK cascade. The cytotoxic effect by ouabain was defined as apoptosis and necrosis using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling reaction technique and lactate dehydrogenase release assay, respectively. In addition, ouabain induced profound caspase-3 activity in the cytotoxic concentrations and DEVD-CHO reversed the cytotoxic action to ouabain, demonstrating the involvement of caspase-3 activation in the cytotoxic action. CONCLUSIONS: Ouabain at different concentrations caused dual effects on proliferation and apoptosis in human prostatic smooth muscle cells. At low concentrations ouabain promoted cell proliferation via a Ca(2+) dependent mechanism and activation of the MEK-p42/44 MAPK pathway; whereas it induced cell apoptosis via the activation of caspase-3 activity at higher concentrations.

Analysis of Variance↗
PubMed2001

Preoperative diagnosis and localization of aldosterone-producing adenoma by adrenal venous sampling after administration of metoclopramide.

BACKGROUND AND PURPOSE: Adrenal venous sampling is the most reliable test to distinguish aldosterone-producing adenoma (APA) from idiopathic hyperaldosteronism (IHA). The diagnostic accuracy can be improved by administration of adrenocorticotropin to minimize pulsatile secretion of aldosterone. Metoclopramide (MCP), a dopamine antagonist, can increase aldosterone secretion promptly without affecting cortisol secretion. This study investigated the diagnostic accuracy of adrenal venous sampling after MCP injection for the preoperative diagnosis and localization of APA. METHODS: Prospective diagnosis and adrenalectomy was based on adrenal venous sampling in 23 patients with a diagnosis of primary aldosteronism. Plasma aldosterone concentrations from adrenal veins and the inferior vena cava were measured before and 30 minutes after intravenous administration of 10 mg MCP. The ratio of bilateral adrenal venous aldosterone concentrations after MCP was used for diagnosis as follows: a ratio greater than 5 indicated APA, less than 3 indicated IHA, and 3-5 indicated an intermediate diagnosis. RESULTS: Catheterization of the right adrenal vein was unsuccessful in three patients. Twelve of 13 patients with an aldosterone ratio greater than 5 after MCP underwent unilateral adrenalectomy, and APA was confirmed in 11 of these patients. One patient with an intermediate diagnosis also had surgically confirmed APA. Six patients had a ratio less than 3. Before MCP administration, 10 of 13 patients with APA had a ratio greater than 5, and three patients had a ratio between 3 and 5; one patient with IHA had a ratio greater than 5. MCP improved the diagnosis of APA to an accuracy of 92% (12/13). Correct diagnosis of APA based on computerized tomography (CT) was 85% (11/13). There was discordance between the findings of adrenal venous sampling and CT in four of 20 patients. CONCLUSIONS: Administration of MCP to stimulate aldosterone secretion during adrenal venous sampling can improve the accuracy of differential diagnosis between APA and IHA.

Adenoma↗