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Biomedical subjects

W Mak

Publications and source records attributed to W Mak.

At least 19 recordsLinked to original sources
PubMed2006

Intron 2 (T/C) CYP46 polymorphism is associated with Alzheimer's disease in Chinese patients.

BACKGROUND: Cholesterol metabolism has been implicated in the pathophysiology of Alzheimer's disease (AD), and cholesterol-related genes are plausible candidate genes for AD. Genetic association of CYP46A1 polymorphisms with AD had been under extensive investigations; however, observations on intron 2 T-->C (rs754203) generated inconclusive results. OBJECTIVE: To analyse an independent data set in a Chinese population to see whether the polymorphic site rs754203 of the CYP46A1 gene is associated with AD. METHODS: We analysed 130 sporadic AD patients and 110 healthy controls of the Southern Chinese origin. RESULTS: An association between the genotype frequency and AD was suggested in the general population (p = 0.047, odds ratio, OR = 1. 61, 95% confidence interval, CI = 0.96-2.70), while the association was most significant in the apolipoprotein E (ApoE) epsilon4-negative group (p = 0.004, OR = 2.54, 95% CI =1.31-4.95). Linkage disequilibrium block prediction results also favoured this association. Consistent with previous reports, intron 3 C-->T (rs4900442) polymorphism did not show any evidence of association; in our data set ApoEepsilon4 was confirmed to be a genetic risk factor for AD (p = 0.0016, OR = 2.76, 95% CI = 1.50-5.11).

Aged↗
PubMed2006

p21 gene polymorphisms in systemic lupus erythematosus.

OBJECTIVE: Cyclin-dependent kinase inhibitor 1A (p21) is a negative regulator in the cell cycle. Development of sex-linked lupus-like syndrome in p21-/- mice and reduced p21 gene expression in patients with systemic lupus erythematosus (SLE) compared with those in healthy controls suggested that p21 is a susceptibility gene of SLE. We investigated the same by a case-control association study. METHODS: Six single nucleotide polymorphisms, p21US G/A, p21DS C/A, p21-1022 G/A, p21C31 C/A, p21In2 G/C and p21UTR T/C, were genotyped in 516 SLE patients and 693 healthy controls. Association of genotypes and alleles with disease, disease phenotypes, haplotypes construction, linkage disequilibrium analysis and p21 mRNA expression were performed. RESULTS: We found a significant association of p21US A allele (OR = 0.23, 95% CI: 0.14-0.38, P < 0.001) and p21-1022 A allele (OR = 1.95, 95% CI: 1.37-2.78, P < 0.001) with SLE. We identified significant differences in the frequencies of haplotypes ht1-ACACCC, which contains p21US A allele, and ht2-GCACCC, which contains p21-1022 A allele, between SLE patients and controls (P < 0.0001). Besides, the p21US GA was associated with SLE patients suffering from arthritis (P = 0.003). We also observed differential p21 mRNA expressions among different genotypes of p21US and p21-1022 which were statistically significant. CONCLUSION: Our results suggested that the p21US A allele and p21-1022 A allele were both associated with the development of SLE, and the p21US A allele was associated with arthritis in SLE patients.

Adult↗
PubMed2006

Myopia as a latent phenotype of a pleiotropic gene positively selected for facilitating neurocognitive development, and the effects of environmental factors in its expression.

Myopia has become an almost pandemic problem in many populations. There are compelling evidence to suggest that myopia is a hereditary condition. However, myopia would constitute a definite selection disadvantage during most stages of human evolution, which is incompatible with its moderate to high prevalence in most modern populations. The rapid upsurge of myopia over just a few decades also implies that its inheritance does not follow any of the usual patterns, and environmental factors may have an important role in precipitating its occurrence in those who are genetically predisposed. Previous studies showed that myopes were, on average, more intelligent than non-myopes, and this association had been attributed to a biological link between eye growth and brain development. We propose a pleiotropic genetic model to explain the atypical epidemiologic and inheritance pattern of myopia and its relationship with neurocognitive development. This pleiotropic gene was positively selected for its facilitation of human intelligence. The myopic component is a latent phenotype; myopia will not be expressed unless some novel external factors are encountered (i.e. a "quirk" phenomenon). Therefore, the myopic component was selectively neutral in our ancestral environment. The net gain in Darwinian fitness enables the pleiotropic gene to attain a high frequency in the human population, as reflected by our current prevalence of myopia.

Animals↗
PubMed2006

Idiopathic inflammatory demyelinating disorders after acute transverse myelitis.

Acute transverse myelitis (ATM) is commonly para-infectious. Recurrent ATM occurs in connective tissue diseases (CTD), infective myelitis and idiopathic inflammatory demyelinating disorders (IIDD) including multiple sclerosis (MS) and neuromyelitis optica (NMO). Previous studies might include NMO and idiopathic recurrent transverse myelitis (IRTM) as MS. The aim was to study the outcome of patients after a first attack of idiopathic ATM. Idiopathic ATM patients over a 6-year period were retrospectively studied. Known causes of myelopathy were excluded. Among 32 patients studied, 20 (63%) had single ATM attack upon follow up for 39-93 months, three developed recurrent ATM related to CTD (two systemic lupus erythematosus and one anti-Ro antibody positive) and nine (28.1%) developed recurrent neuroinflammation compatible with IIDD. Among IIDD patients, three had NMO, two restricted variant of NMO, three IRTM and one classical MS. NMO, its variant and IRTM had mean spinal MRI abnormality of 3.7, 2.1 and 3.9 vertebral segments respectively while non-recurrent ATM had 1.6 vertebral segments. Four (80%) of the five patients with NMO or its variant had poor neurological prognosis versus only one (5%) of non-recurrent ATM patients. IRTM patients had advanced mean onset age, 62 years vs. 43 years for non-recurrent ATM patients. In IIDD patients presenting with ATM as first attack of neuroinflammation, NMO and its variant (56%) were most frequent, then IRTM (33%), with classical MS (11%) the rarest. As long-term treatments for NMO are different from MS, early recognition of NMO and its variant is important for prevention of serious neurological deficits.

Adult↗
PubMed2005

Cerebral infarcts complicating tuberculous meningitis.

Cerebral infarction (CI) is a serious complication of tuberculous meningitis (TBM). It can be asymptomatic or symptomatic, causing stroke. We studied 40 TBM patients. All had initial CT brain scan, CT/MRI brain scan 3 months later and urgent CT brain scan for deterioration. CI was classified into lacunar infarction (LI) or large artery infarction (LAI). Twelve (30%) had CI, in 9 (23%) it was symptomatic and in 3 (8%) silent. Seven (58%) had LAI +/- LI. Eight (67%) had multiple CI. Two died from brainstem CI and 6 were dependent at 1 year. Patients with LAI might develop posterior circulation CI more frequently than those with LI only. CI is a common complication of TBM locally, with LAI and multiple CI being common. Two thirds of TBM patients complicated by CI had poor prognosis despite adjunctive dexamethasone treatment.

Adolescent↗
PubMed2005

Cerebral venous thrombosis in a gentleman presenting with fever, convulsion and frontotemporal haemorrhages.

Cerebral venous thrombosis (CVT) is an uncommon but serious type of stroke. Thrombosis may involve the cortical or deep veins or the venous sinuses. The presenting clinical features are non-specific. We report a 48-year-old man with CVT who presented with fever, bitemporal throbbing headache, and generalised convulsion. Computed tomography (CT) of the brain revealed acute haemorrhages over right anterior frontal and posterior temporal regions with surrounding oedema and right anterior temporal subcortical oedema. The initial diagnosis was herpes simplex encephalitis. Absence of venous flow over the right transverse and sigmoid sinuses during the venous phase of digital subtraction angiography (DSA) revealed CVT. He was anti-coagulated for 6 months. An underlying cause of CVT was not detected. A high index of suspicion is required when risk factors of CVT are present. CT brain may be normal or showing non-specific findings. Magnetic resonance imaging plus venography, CT venography, or DSA is diagnostic.

Angiography, Digital Subtraction↗
PubMed2005

Wilson's disease with depression and parkinsonism.

Wilson's disease (WD) is an autosomal recessive disorder with reduced biliary excretion of copper plus impaired formation of ceruloplasmin, leading to copper accumulation in the liver, brain, kidney, and cornea. Clinical manifestations include liver damage, psychiatric symptoms, and neurological features. We report a 35-year-old woman with a history of deranged liver functions who had severe depression several years later and eventually presented with parkinsonian features. The underlying diagnosis is WD and family screening revealed WD in 2 other siblings. She could not tolerate penicillamine because of fever and leucopenia. While taking trientine hydrochloride and zinc sulphate, her parkinsonism improved and her depression remained in remission. WD should be considered in patients with unexplained liver function derangement or psychiatric symptoms. Early diagnosis and initiation of specific treatment are crucial in minimising any further cerebral and hepatic damage as well as securing possible improvement in organ functions.

Adult↗
PubMed2005

A possible explanation for the racial difference in distribution of large-arterial cerebrovascular disease: ancestral European settlers evolved genetic resistance to atherosclerosis, but confined to the intracranial arteries.

The pattern of cerebral atherosclerosis is not the same among different races. White patients rarely have intracranial large arterial steno-occlusive disease even if their systemic arteries are extensively involved, while non-white patients frequently have their intracranial arteries affected. We postulate that during human population diversification, those who settled in Europe had acquired a stroke-suppressor genotype that increases their resistance against atherogenesis, but with protection confined to the intracranial large arteries. The contemporary affluent lifestyle accelerates the development of atherosclerosis. In the whites, it involves the whole arterial bed except the intracranial vessels. People living in non-Western countries used to have a healthier way of living. They did not develop significant atherosclerotic diseases until recently when a westernised lifestyle was adopted. Unlike the whites, their intracranial arteries will not be spared. Atherosclerosis has become a major cause of premature mortality in the modern world, and an anti-atherogenic mechanism would confer a selection advantage. With further adaptive intensification, this protection may extend to the rest of the arterial bed. As a result, future Homo sapiens will be able to tolerate an affluent lifestyle without much adverse sequel such as premature vascular death. Alternatively, if the mediator of this anti-atherogenic mechanism can be identified and applied therapeutically, we will have an ultimate mean to prevent atherosclerosis.

Antioxidants↗
PubMed2005

Dedicated neonatal retrieval teams improve delivery room resuscitation of outborn premature infants.

BACKGROUND: Morbidity related to ineffective resuscitation and stabilization of premature infants is increased when delivery occurs outside tertiary perinatal centers. The regional neonatal transport team received extensive training to expand their scope of practice to include delivery room resuscitation allowing them to attend high-risk deliveries in community hospitals when maternal transfer was not possible. OBJECTIVE: Compare the resuscitation and stabilization of premature infants when a specialized neonatal retrieval team (SNRT) is in attendance at delivery with immediate resuscitation and stabilization performed by the referral hospital team (RHT). STUDY DESIGN: We assessed the impact of a specially trained neonatal transport team by comparing the initial resuscitation process, airway and vascular access skills, illness severity and patient stabilization in both groups. RESULTS: Neonates resuscitated by the RHT were more likely to receive oxygen, mask CPAP, bag and mask ventilation and cardiac compressions for a significantly longer time period. Neonates resuscitated by the SNRT were intubated more promptly (8.5 minutes {1 to 22} vs 16 minutes {1 to 90}, p=0.035) following a fewer number of attempts. The endotracheal tube was correctly positioned on radiological assessment in 72% of cases in the SNRT group vs 38.1% in the RHT group (p<0.001). Many neonates had no vascular access (31%) and were profoundly hypothermic (38.5%) on arrival of the SNRT. Although there was no significant difference in maximum FiO(2) or oxygenation index, babies with respiratory distress syndrome resuscitated by the RHT were less likely to receive surfactant therapy (76.6 vs 34.4%, p=0.001). There was no difference in transport-related mortality between the groups CONCLUSIONS: The presence of a highly skilled transport team at a high-risk preterm delivery improves the quality of neonatal resuscitation by increasing intubation success rates and achieving earlier vascular access. Neonates resuscitated by dedicated neonatal retrieval teams were less likely to become significantly hypothermic. Although the severity of RDS was similar neonates in the RHT were less likely to receive surfactant.

Analysis of Variance↗
PubMed2005

An epidemiological study of motor neuron disease in Hong Kong.

Worldwide, the incidence of motor neuron disease (MND) has been increasing steadily over recent decades. We reported a follow-up epidemiology study of MND in this locality. We identified the subjects from the computer database of the government hospital system between 1 January 1997 and 31 January 2002 by searching the ICD code starting from 335.xx. Every retrieved case or their records were reviewed and validated by neurologist(s) of the responsible regional hospitals which the patients attended. One hundred and twenty cases from seven regional hospitals (serving 48.05% of the HKSAR population) were identified, validated and confirmed to be MND or related diseases. Ninety-eight new cases were diagnosed during the study period. Average age of onset was 58.76 years; SD 14.12 (28-89) years. Male to female ratio was 1.72:1. Peak age of onset was 60-64 years without sex difference. The adjusted incidence rate was 0.60/100,000/year. The adjusted point prevalence at the prevalence date (31 January 2001) was 3.04/100,000. Despite the incidence and prevalence of MND among Hong Kong Chinese, it remained low compared to worldwide figures, and our data suggested a significant rise of MND or related disease in the last decade. A territory-wide prospective epidemiological study is indicated.

Adult↗
PubMed2005

Bath-related headache.

Bath-related headache (BRH) is a rare primary headache syndrome. We present our experience over seven years and review all reported cases of BRH. Thirteen patients, including six from our group, are described. BRH occurred exclusively in middle-aged or elderly Oriental women (mean age 51 years, range 32-67. Hong Kong 6 cases, Taiwan 4 cases, Japan 3 cases). The typical presentation was a uniphasic cluster of severe headache recurrently triggered by bathing or other activities involving contact with water. Each attack lasted 30 min to 30 h. Onset was hyperacute, consistent with that of thunderclap headache. Reversible multisegmental cerebral vasoconstriction was found in two patients. No underlying secondary causes were identified. Response to acute treatment was generally unsatisfactory, but headache could be prevented by avoiding the specific trigger(s). BRH runs a self-limiting course; all patients remitted within three months after onset. Nimodipine may shorten the duration of illness.

Adult↗
PubMed2005

Cerebrospinal fluid to serum glucose ratio in non-hypoglycorrhachic neurological conditions.

OBJECTIVE: To explore the relevance of cerebrospinal fluid to serum glucose ratio in non-hypoglycorrhachic conditions. DESIGN: Retrospective observational study. SETTING: Neurology ward, university teaching hospital, Hong Kong. PATIENTS: Adult patients with conditions unrelated to hypoglycorrhachia who underwent lumbar puncture. MAIN OUTCOME MEASURES: Cerebrospinal fluid and simultaneous serum glucose concentrations, and their ratio to each other. RESULTS: Between September 1998 and August 2003, 170 cerebrospinal fluid and serum glucose samples were collected from 138 patients. Mean cerebrospinal fluid to serum glucose ratio was 0.61 (standard deviation, 0.142; range, 0.21-1.00). With the exception of cerebrospinal fluid protein level, laboratory parameters were similar among different diseases. The glucose ratio was lower than 0.6 in 43% and lower than 0.5 in 19% of samples. Cases with a low glucose ratio appeared to have higher serum glucose concentrations (significant among groups with different glucose ratios, P<0.001). The mean glucose ratio (0.65) was also significantly higher in patients with serum glucose concentration of lower than 7.8 mmol/L compared with those with serum glucose concentration between 7.8 and 11.1 mmol/L (mean, 0.46), or higher than 11.1 mmol/L (mean, 0.46) [P<0.001]. There was a strong negative correlation between the glucose ratio and serum glucose concentration (r= -0.704, P<0.001). CONCLUSION: A lowered cerebrospinal fluid to serum glucose ratio is often seen in the absence of an appropriate disorder, especially when simultaneous serum glucose concentration is elevated. This may be explained by the saturation kinetics of glucose transportation in hyperglycaemia, and the time lag for cerebrospinal fluid and glucose to equilibrate when the blood level fluctuates.

Adult↗
PubMed2004

Surgical treatment for tubal disease in women due to undergo in vitro fertilisation.

BACKGROUND: Tubal disease, and particularly hydrosalpinx, has a detrimental effect on the outcome of in-vitro fertilisation (IVF). It has been less clear whether surgical intervention for tubal disease prior to IVF is effective in improving the likelihood of successful outcome. Most data are retrospective or poorly controlled. To date no single prospective randomised trial has shown a significant benefit from such surgical treatment prior to IVF. OBJECTIVES: To assess the value of surgical treatment for tubal disease prior to IVF. SEARCH STRATEGY: We searched the Cochrane Menstrual Disorders and Subfertility Group trials register (10 March 2004), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2004), MEDLINE (January 1966 to February 2004), EMBASE (January 1985 to February 2004), reference lists of articles and contacted researchers in the field. SELECTION CRITERIA: All trials comparing a surgical treatment for tubal disease with a control group generated by randomisation were considered for inclusion in the review. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. The studied outcomes were live birth (and ongoing pregnancy), pregnancy, ectopic pregnancy, miscarriage, multiple pregnancy and complications. MAIN RESULTS: Three randomised controlled trials involving 295 (or couples) were included in this review. The odds of ongoing pregnancy and live birth (Peto odds ratio (OR) 2.13, 95% confidence interval (CI) 1.24 to 3.65) were increased with laparoscopic salpingectomy for hydrosalpinges prior to IVF. The odds of pregnancy were also increased (Peto odds ratio (OR )1.75, 95%CI 1.07 to 2.86). There was no significant difference in the odds of ectopic pregnancy (Peto OR 0.42, 95%CI 0.08 to 2.14), miscarriage (Peto OR 0.49, 95%CI 0.16 to 1.52) or treatment complications (Peto OR 5.80, 95%CI 0.35 to 96.79). No data were available concerning the odds of multiple pregnancy. REVIEWERS' CONCLUSIONS: Laparoscopic salpingectomy should be considered for all women with hydrosalpinges prior to IVF treatment. Currently unilateral salpingectomy for a unilateral hydrosalpinx (bilateral salpingectomy for bilateral hydrosalpinges) should be recommended, although this requires further evaluation. Further randomised trials are required to assess other surgical treatments for hydrosalpinx, such as salpingostomy, tubal occlusion or needle drainage of a hydrosalpinx at oocyte retrieval. The role of surgery for tubal disease in the absence of a hydrosalpinx is unclear and merits further evaluation.

Fallopian Tube Diseases↗