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Biomedical subjects

K K Lau

Publications and source records attributed to K K Lau.

At least 19 recordsLinked to original sources
PubMed2005

Japanese encephalitis in Hong Kong.

OBJECTIVES: To review past and present patterns of occurrence of Japanese encephalitis in Hong Kong and across Asia. A better understanding of the disease should facilitate the formulation of an effective strategic plan to prevent a future epidemic. DATA SOURCES: Report of local cases, and literature search of MEDLINE up to November 2004. STUDY SELECTION: Literature and data related to Japanese encephalitis. DATA EXTRACTION: Relevant information and data were reviewed by the authors. DATA SYNTHESIS: Since 16 July 2004, under the ordinance of Hong Kong, Japanese encephalitis has been a notifiable disease. In the past, Japanese encephalitis has reached epidemic proportions in Japan, South Korea, and some areas in China. It has spread globally and has a worldwide incidence of 35 000 to 50 000 cases per year with 10 000 deaths. Mortality is about 30% and survivors often suffer serious long-term morbidity. In 2004, there were five local cases of Japanese encephalitis in Hong Kong. Subsequent serological surveillance of serum samples from 1547 local inhabitants revealed that 37 were positive, ie 2.4% of local inhabitants had been exposed to the Japanese encephalitis virus in the past. Most local inhabitants are immunologically naive to Japanese encephalitis virus. Most infections in endemic areas are asymptomatic. Patients with symptomatic Japanese encephalitis usually present with fever, headache, and confusion. Other signs include neurosis, poliomyelitis, and convulsion. Investigations including magnetic resonance imaging, electroencephalography, and single photon emission computed tomography are not specific. A definitive diagnosis depends on serological studies. Treatment is mainly supportive. CONCLUSIONS: The control of Japanese encephalitis in Hong Kong relies on an accurate surveillance system, vector control, vector avoidance, and vaccination of the at-risk population. At present, vaccination should be limited to travellers to endemic areas who would stay for longer than 1 month.

Encephalitis, Japanese↗
PubMed2005

Spinocerebellar ataxia type 6.

We report a 39-year-old woman with spinocerebellar ataxia type 6. She presented with ataxia and a 3-year history of progressive ataxia and recurrent falls. There was no relevant family history. Genetic tests revealed an expanded allele of 24 CAG repeats at the spinocerebellar ataxia type 6 locus. This appears to be the first case reported in Hong Kong. As genetic testing becomes more widely available and clinical awareness increases, more such patients are expected to be diagnosed.

Adult↗
PubMed2005

A registry of tuberculous meningitis in Hong Kong.

BACKGROUND: A prospective observational study of the presentation, diagnosis, treatment and outcome of tuberculous meningitis (TBM). METHODS: Demographic characteristics, clinical information, treatment and progress of TBM patients were followed. Their outcomes were ascertained every 6 months for 3 years after diagnosis. Prognostic factors associated with death or full recovery were examined using multivariate Cox's and logistic regression models, respectively. RESULTS: Between 1993 and 2000, 166 TBM patients were recruited. Their mean age was 42.9, 153 were Chinese and 81 were males; 92% received HRZS (H = isoniazid; R = rifampicin; Z = pyrazinamide; S = streptomycin), HRZE (E = ethambutol) or HRZES. Steroids were given to 105 patients, with no significant effect on outcome. After 3 years of follow-up, 110 patients had completely recovered, 20 survived with disability and 26 died. Death was significantly associated with older age, lower cerebrospinal fluid (CSF) lymphocyte and poorer consciousness levels at the time of presentation, while full recovery was associated with younger age, being female and absence of complications. CONCLUSIONS: Relatively good outcomes of TBM cases were documented in this Hong Kong study with a case-fatality ratio of 15.7% (26/166) up to 3 years. Early recognition, diagnosis and administration of effective treatment regimens were probably the most important factors in reducing mortality and morbidity.

Adolescent↗
PubMed2004

Pediatric IgA nephropathy: clinical features at presentation and outcome for African-Americans and Caucasians.

AIM: To determine the disease severity at onset and outcome for African-American and Caucasian pediatric patients with IgA nephropathy diagnosed at the Le Bonheur Children's Medical Center since 1990. DESIGN/METHODS: The study population included all patients diagnosed with IgA nephropathy at the Le Bonheur Children's Medical Center from January 1990 through February 2004. All were below age 18 at biopsy. Clinical features assessed at diagnosis were age, gender, presence of hypertension, history of macroscopic hematuria, degree of proteinuria, severity of renal histology and pattern for immunofluorescent reactants. STATISTICS: Student's t-test was used to compare age at biopsy and length of follow-up between the 2 groups. Fisher's exact test was used to compare features at presentation and patterns of immunofluorescence. Kidney survival was predicted by the Kaplan-Meier method. RESULTS: Forty-seven patients (17 African-American, 29 Caucasian) were studied. Clinical features at diagnosis and pattern for all immunofluorescent reactants did not differ significantly between the 2 groups. Mesangial deposition of C1q occurred in 4/17 African-Americans as compared to 1/27 Caucasians (p = 0.06). Four patients (2 African-Americans, 2 Caucasians) progressed to end-stage renal disease. Predicted kidney survival was 96% (94% in African-Americans and 97% in Caucasians) at 1 year and 91% (94% in African-Americans and 89% in Caucasians) at 5 years from diagnosis. Mean time from diagnosis to end-stage renal disease or last follow-up was 3.3 years (3.8 for African-Americans, 3.0 for Caucasians). Macroscopic hematuria occurred prior to diagnosis for 90% of the Caucasian as compared to 61% of the African-American patients (p = 0.03). Urinalysis was normal at last follow-up visit for 24% of African-American patients and 32% of Caucasian patients. CONCLUSION: In a relatively small sample from a single center, except for the difference in macroscopic hematuria, clinical features at diagnosis and outcome of IgA nephropathy appear similar for African-American and Caucasian pediatric patients.

Black or African American↗
PubMed2004

Clinical features of hereditary spinocerebellar ataxia diagnosed by molecular genetic analysis.

OBJECTIVE: To assess the frequency and clinical features of different types of hereditary spinocerebellar ataxia in Hong Kong. DESIGN: Cross-sectional study using a questionnaire and clinical examination, with the majority of the information retrospectively collected. SETTING: Three regional hospitals, Hong Kong. PARTICIPANTS: All patients with spinocerebellar ataxia that was confirmed by molecular genetic tests between January 2001 and October 2003. MAIN OUTCOME MEASURES: History, latest physical examination results, clinical investigation results, and genetic profiles. RESULTS: A total of 16 Chinese patients had received diagnoses of spinocerebellar ataxia. These patients had spinocerebellar ataxia type 1 (n=3), spinocerebellar ataxia type 3 (Machado-Joseph disease; n=12), and dentatorubro-pallidoluysian atrophy (n=1). The most common manifestation was ataxia (15/16), followed by pyramidal signs (12/16). Other features such as bulbar dysfunction, ophthalmoplegia, neuropathy, and cognitive impairment were present but variable. CONCLUSIONS: The clinical manifestations of different types of spinocerebellar ataxia overlap, and genetic study is necessary to confirm the diagnosis. The frequency of spinocerebellar ataxia type 3 is greater than that of other types among these Chinese patients. The age of onset of this type may correlate inversely with the number of CAG repeats.

Adult↗
PubMed2003

Kennedy's disease.

Kennedy's disease is an X-linked, neurodegenerative disorder, characterised by lower motor neuron syndrome. This report gives the clinical details of six male patients with Kennedy's disease diagnosed at Princess Margaret Hospital. Three were initially diagnosed with other neurological diseases, with the diagnosis of Kennedy's disease made after genetic testing. This hereditary disease should be considered in male patients with muscle weakness, particularly those with a presentation suggesting atypical motor neuron disease.

Adult↗
PubMed2002

Epidemiological study of multiple sclerosis in Hong Kong Chinese: questionnaire survey.

OBJECTIVE: To study the epidemiology of multiple sclerosis in Hong Kong Chinese. DESIGN: Cross-sectional questionnaire survey. SETTING: Neurology and paediatric neurology departments in Hong Kong from January through June 1999. PARTICIPANTS: All confirmed multiple sclerosis patients. MAIN OUTCOME MEASURES: Demographic data, investigation results, Kurtzke's Expanded Disability Status Scale during the last follow-up visit, number of relapses between 1997 and 1998, and treatments used/currently in use. RESULTS: Fifty-three Chinese multiple sclerosis patients were identified. The prevalence was thus estimated to be 0.77 per 100,000 population. This low prevalence was also noted in other multiple sclerosis studies from South-East Asia (range, 0.8-4 per 100,000 population). The female to male ratio among the Chinese multiple sclerosis sufferers was 9.6:1, a figure somewhat higher than that reported in the other studies from South-East Asia (range, 3.2-6.6:1). The Chinese multiple sclerosis patients in this study also had a high spinal cord involvement (66%) and a low presence of cerebrospinal fluid oligoclonal banding (40%). These findings were different from those in Caucasian multiple sclerosis patients. CONCLUSION: Multiple sclerosis in Hong Kong Chinese has a low prevalence, a high female to male ratio, and a low cerebrospinal fluid oligoclonal banding presence.

Adult↗
PubMed2002

Respiratory insufficiency in a Chinese adult with mitochondrial myopathy.

Mitochondrial myopathy is an important but uncommon cause of respiratory insufficiency in adults. We report the first case of respiratory insufficiency associated with adult-onset mitochondrial myopathy seen in a Chinese adult in Hong Kong. The patient presented with peripheral oedema and shortness of breath over 2 to 3 days. There was a history of gradual progressive limb weakness over approximately 2 years, hypertrophic cardiomyopathy, intermittent diarrhoea, and weight loss. The diagnosis was made by skeletal muscle biopsy and molecular study, which revealed the A3243G point mutation.

Adult↗
PubMed2000

Phenytoin poisoning after using Chinese proprietary medicines.

We report a case of poisoning resulting from the use of Chinese proprietary medicines (CPM) containing anticonvulsants phenytoin, carbamazepine and valproate. The manufacturer's information leaflets did not mention any of these prescription drugs. As a consequence, the patient was admitted comatose due to severe phenytoin poisoning. We are not aware of any reported case of severe poisoning due to CPM adulterated with anticonvulsants and this is possibly the first case.

Adult↗
PubMed2000

Interferon treatment for multiple sclerosis patients in Hong Kong.

We report on nine patients with multiple sclerosis who had received interferon beta-1a treatment for 6 months or more. Seven patients were Chinese and two were Caucasian. Seven patients had the relapsing-remitting type of multiple sclerosis, one had the primary-progressive type, and one had the progressive-relapsing type. Among the six compliant patients with the relapsing-remitting type of disease, four had less frequent relapses after treatment. This study could not show whether or not the use of interferon beta-1a was beneficial to non-compliant patients, or patients with other types of multiple sclerosis.

Adolescent↗
PubMed1999

GLLS for optimally sampled continuous dynamic system modeling: theory and algorithm.

The original generalized linear least squares (GLLS) algorithm was developed for non-uniformly sampled biomedical system parameter estimation using finely sampled instantaneous measurements (D. Feng, S.C. Huang, Z. Wang, D. Ho, An unbiased parametric imaging algorithm for non-uniformly sampled biomedical system parameter estimation, IEEE Trans. Med. Imag. 15 (1996) 512-518). This algorithm is particularly useful for image-wide generation of parametric images with positron emission tomography (PET), as it is computationally efficient and statistically reliable (D. Feng, D. Ho, Chen, K., L.C. Wu, J.K. Wang, R.S. Liu, S.H. Yeh, An evaluation of the algorithms for determining local cerebral metabolic rates of glucose using positron emission tomography dynamic data, IEEE Trans. Med. Imag. 14 (1995) 697-710). However, when dynamic PET image data are sampled according to the optimal image sampling schedule (OISS) to reduce memory and storage space (X. Li, D. Feng, K. Chen, Optimal image sampling schedule: A new effective way to reduce dynamic image storage space and functional image processing time, IEEE Trans. Med. Imag. 15 (1996) 710-718), only a few temporal image frames are recorded (e.g. only four images are recorded for the four parameter fluoro-deoxy-glucose (FDG) model). These image frames are recorded in terms of accumulated radio-activity counts and as a result, the direct application of GLLS is not reliable as instantaneous measurement samples can no longer be approximated by averaging of accumulated measurements over the sampling intervals. In this paper, we extend GLLS to OISS-GLLS which deals with the fewer accumulated measurement samples obtained from OISS dynamic systems. The theory and algorithm of this new technique are formulated and studied extensively. To investigate statistical reliability and computational efficiency of OISS-GLLS, a simulation study using dynamic PET data was performed. OISS-GLLS using 4-measurement samples was compared to the non-linear least squares (NLS) method using 22-measurement samples, GLLS using 22-measurement samples and OISS-NLS using 4-measurement samples. Results demonstrated that OISS-GLLS was able to achieve parameter estimates of equivalent accuracy and reliability in comparison to NLS or GLLS using finely sampled measurements (22-measurement samples), or OISS-NLS using optimally sampled measurements (4-measurement samples). Further more, as fewer measurement samples are used in OISS-GLLS, this algorithm is computationally faster than NLS or GLLS. Therefore, OISS-GLLS is well-suited for image-wide parameter estimation when PET image data are recorded according to the optimal image sampling schedule.

Algorithms↗
PubMed1999

Transcriptional profiling of human microvascular endothelial cells in the proliferative and quiescent state using cDNA arrays.

Endothelial cells are known to be a rich source of transcriptional gene expression. Recent technological advances now permit the detailed profiling of mRNA expression using arrays of known cDNAs on blots. We have used such arrays to examine expression of mRNA by primary isolates of human foreskin microvascular endothelial cells in the proliferative and quiescent state. Cells were stimulated by a combination of known growth factors for these cells including epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and 'endothelial cell growth supplement (ECGS)' either alone or in combination. Analysis showed the expression of many mRNAs but of the 588 examined, only one, namely monocyte chemotactic protein-1 (MCP-1), showed a decrease on treatment with EGF. A combination of image grabbing followed by subtractive densitometry enabled identification of the mRNAs upregulated in proliferating endothelium. In consideration of the possibility of selective vascular targeting, of particular interest was the increase in expression of the mRNA for the cell surface proteins vascular endothelial (VE-) and neural (N-) cadherin and alpha5, alphav, beta1 and beta3 integrins. The alpha5 integrin offers a previously unrecognized opportunity for vascular targeting.

Journal Article↗
PubMed1999

Use of intravenous immunoglobulin in a patient with refractory myasthenia gravis associated with malignant thymoma.

We report on a case of refractory myasthenia gravis that was managed by using intravenous immunoglobulin. A 35-year-old Chinese woman with malignant thymoma-associated myasthenia gravis was treated by total thymectomy, followed by chemotherapy. Thirty months later, she developed respiratory failure and required mechanical ventilation for 2 months. A course of intravenous immunoglobulin was given and her condition improved significantly. Two weeks later, the patient became ambulatory, was prescribed oral pyridostigmine, and was discharged home.

Journal Article↗
PubMed1998

Isolation of two chymotrypsins from grass carp.

Two chymotrypsins were purified from the hepatopancreas of grass carp (Ctenopharyngodon idellus) by chromatographies on phenyl-Sepharose and Q-Sepharose. The molecular weights of chymotrypsins I and II were 28 and 27 kDa, respectively. The two chymotrypsins showed similar susceptibility to inhibitions by phenylmethylsulfonyl fluoride and soybean trypsin inhibitor, but differed in their response to tosyl-L-phenylalanine chloromethyl ketone and aprotinin in which chymotrypsin I was more resistant. Chymotrypsin I was a less typical chymotrypsin and exhibited lower catalytic efficiency with the chymotrypsin-specific ester and amide substrates, when compared with chymotrypsin II. For both chymotrypsins, optimal activity was detected in the pH range 7.0-8.5.

Animals↗
PubMed1998

pha-4 is Ce-fkh-1, a fork head/HNF-3alpha,beta,gamma homolog that functions in organogenesis of the C. elegans pharynx.

The C. elegans Ce-fkh-1 gene has been cloned on the basis of its sequence similarity to the winged-helix DNA binding domain of the Drosophila fork head and mammalian HNF-3alpha,beta,gamma genes, and mutations in the zygotically active pha-4 gene have been shown to block formation of the pharynx (and rectum) at an early stage in embryogenesis. In the present paper, we show that Ce-fkh-1 and pha-4 are the same gene. We show that PHA-4 protein is present in nuclei of essentially all pharyngeal cells, of all five cell types. PHA-4 protein first appears close to the point at which a cell lineage will produce only pharyngeal cells, independently of cell type. We show that PHA-4 binds directly to a 'pan-pharyngeal enhancer element' previously identified in the promoter of the pharyngeal myosin myo-2 gene; in transgenic embryos, ectopic PHA-4 activates ectopic myo-2 expression. We also show that ectopic PHA-4 can activate ectopic expression of the ceh-22 gene, a pharyngeal-specific NK-2-type homeodomain protein previously shown to bind a muscle-specific enhancer near the PHA-4 binding site in the myo-2 promoter. We propose that it is the combination of pha-4 and regulatory molecules such as ceh-22 that produces the specific gene expression patterns during pharynx development. Overall, pha-4 can be described as an 'organ identity factor', completely necessary for organ formation, present in all cells of the organ from the earliest stages, capable of integrating upstream developmental pathways (in this case, the two distinct pathways that produce the anterior and posterior pharynx) and participating directly in the transcriptional regulation of organ specific genes. Finally, we note that the distribution of PHA-4 protein in C. elegans embryos is remarkably similar to the distribution of the fork head protein in Drosophila embryos: high levels in the foregut/pharynx and hindgut/rectum; low levels in the gut proper. Moreover, we show that pha-4 expression in the C. elegans gut is regulated by elt-2, a C. elegans gut-specific GATA-factor and possible homolog of the Drosophila gene serpent, which influences fork head expression in the fly gut. Overall, our results provide evidence for a highly conserved pathway regulating formation of the digestive tract in all (triploblastic) metazoa.

Animals↗
PubMed1998

Acute encephalitis complicating rubella.

During an epidemic of rubella in Hong Kong between October 1996 and June 1997, four male patients presented with rubella complicated by encephalitis, the symptoms of which started 1 to 5 days after the appearance of the rash characteristic of rubella. Two patients recovered completely within 1 week and one complained of a slight impairment of short-term memory. Severe cerebral oedema, and herniation across the brainstem and cerebellum developed in the fourth patient, who died 15 days later. The presence of serum immunoglobulin M antibody against rubella virus was demonstrated in all four patients; one patient also had immunoglobulin M antibody against rubella virus in his cerebrospinal fluid. No virus could be isolated during post-mortem examination of the fourth patient.

Journal Article↗