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Biomedical subjects

V Wong

Publications and source records attributed to V Wong.

At least 127 records · Page 7Linked to original sources
PubMed1992

Adrenoleukodystrophy in a Chinese boy.

We report the first Chinese boy with adrenoleukodystrophy (ALD) who presented with hyperpigmentation, behavioral change and demyelination shown in magnetic resonance imaging of the brain. ALD was confirmed by the elevation of very long chain fatty acid in the serum and biochemical evidence of adrenal insufficiency. A trial of special diet with restriction of very long chain fatty acid and addition of glyceryl trierucate/glycerol trioleate oil (GTEO or Lorenzo's oil) failed to prevent clinical deterioration. The child had progressive visual loss and spastic tetraparesis despite dietary manipulation, adrenal steroid replacement and intravenous gammaglobulin treatment.

Adrenoleukodystrophy↗
PubMed1992

Deletions, duplications and novel restriction fragment length polymorphism in Duchenne and Becker muscular dystrophies.

To determine the mutations of Southern Chinese with Duchenne and Becker muscular dystrophies (DMD, BMD), we analysed 28 DMD and BMD patients in 24 unrelated families for intragenic deletions and duplications by using cDNA probes covering the entire 14 kb of the dystrophin gene. Deletions were detected in nine unrelated patients (seven patients by probe 8 and two by probe 2b-3). Gene duplications were detected by probe 1-2a in two patients with the duplication bands confirmed in both Hind III and Bgl II digests and by densitometry. A third patient was found to have a junction fragment with Bgl II and a duplication band with Hind III by probe 5b-7. Therefore 50% of the 24 unrelated families were found to have either deletions or duplications. A previously undescribed restriction fragment length polymorphism (RFLP) was found in one family with probe 5b-7 in Bgl II digests which was found to segregate with the disease phenotype. This new RFLP was not detected in over 70 unrelated X chromosomes we have examined so far, and appeared to be "private" for this family. The presence of this new restriction site may or may not be the mutation responsible for the disease phenotype.

Asian People↗
PubMed1992

Myasthenia gravis in Hong Kong Chinese. 1. Epidemiology and adult disease.

A territory-wide study of myasthenia gravis (MG) was conducted in Hong Kong. Two hundred and sixty-two Chinese patients (159 adult and 103 paediatric onset) were identified, corresponding to a point prevalence and period prevalence of 53.5 and 62.2 per million respectively, and an average annual incidence of 4.0 per million population. Nine patients died, 7 from MG, giving a case fatality rate of 0.027. Female predominance was present in the whole group of patients (female to male ratio 1.6:1) and in those with adult disease (ratio 2.1:1), but not in those with onset in childhood (ration 1.1:1). Onset of disease was most common in the first 3 decades of life, and became less common in subsequent decades. Juvenile onset MG occurred in 39.3% of patients and restricted ocular MG in 47.9%. Familial occurrence was found in 5 patients. In the 159 adult onset patients, ocular disease was most common (32.7%), followed by mild generalised (29.6%), moderately severe generalised (24.5%), fulminating (11.9%) and late severe disease (1.3%). The mean age of onset of symptoms was 36.7 years. The symptomatology was similar to that of Caucasoid populations. Autoimmune thyroid disease was the commonest associated disease, and the incidence of thymoma among thymic abnormalities was high at 38%.

Adolescent↗
PubMed1992

Myasthenia gravis in Hong Kong Chinese. 2. Paediatric disease.

In a study covering 85% of the population of Hong Kong, 39% of all myasthenia gravis (MG) patients, i.e. 103 individuals (54 girls and 49 boys) were found to have had MG with onset before puberty. Two patients had transient neonatal MG, 20 had early onset juvenile MG and 81 had late onset juvenile MG. Restricted ocular MG occurred in 71% of patients and the remainder had generalised MG. The median age at onset was 4 years. Complete remission occurred in 34 patients (34%), a good response in 14 (14%), and fair response in 32 (32%). The clinical course remained static in 16 patients (16%) and 3 patients deteriorated. Two patients died, 1 with myasthenic crisis and the other with cholinergic crisis. All patients, except 2 with neonatal MG, were initially treated with anticholinesterase, but 24% also required steroid therapy. Thymectomy was performed for 12 patients, of whom 5 (42%) showed marked improvement. Thymic histology was normal in 3, showed hyperplasia in 6, non-invasive thymoma in 1 and involution in 2. The most commonly associated disease was Graves' disease which occurred in 7 patients (7%).

Adolescent↗
PubMed1992

Reactivation of polyomavirus in bone marrow transplant recipients.

Polyomavirus was detected in the urine samples of 12 (48%) out of 25 patients within three months of receiving a bone marrow transplantation. The virus was first detected 11 to 46 days after the transplantation and excretion persisted for up to 42 days. Detection of the virus was not associated with symptoms and it seemed to be a marker of immunosuppression.

Bone Marrow Transplantation↗
PubMed1992

Studies of a spontaneous lethal mutation at the albino locus in SELH/Bc mice.

We report a new mutation at the albino locus in SELH/Bc mice. The mutation arose spontaneously in a male mouse that appeared to be a somatic and germ line mosaic for a new albino (c) allele, provisionally named cBc. The mutation is a recessive lethal, causing embryonic death soon after implantation. We have shown that there is no detectable activity of the Mod-2 allele in cis with the mutation and conclude that the mutation is probably a deletion that includes the c locus, the Mod-2 locus, the intervening 2 cM, and at least one locus essential for postimplantation embryonic survival, either proximal to the c locus or distal to the Mod-2 locus. This new mutation is similar to most previously reported spontaneous mutations at the albino locus in that it arose in a somatic and germ line mosaic mutant animal but differs from them in that it is an embryonic lethal when homozygous and is apparently a deletion. SELH/Bc mice appear to have a high mutation rate. This lethal albino mutation that appears to be a postmeiotic deletion should be useful in the search for the mechanism of mutagenesis in SELH/Bc mice. It may also be useful in mapping essential genes in the c-locus region.

Albinism↗
PubMed1992

Ozone-induced acute tracheobronchial epithelial injury: relationship to granulocyte emigration in the lung.

To investigate the relationship between granulocyte emigration and epithelial injury in specific airway generations of the tracheobronchial tree following short-term ozone exposure, we exposed rhesus monkeys for 8 h to 0.00 (controls) or 0.96 ppm ozone with post-exposure periods of 1, 12, 24, 72, and 168 h in filtered air before necropsy. There were five control and three exposed monkeys for each of the post-exposure times for a total of 20 monkeys. Neutrophils isolated from peripheral blood and labeled with 111In-tropolonate were infused in the cephalic vein in unanesthetized monkeys (except the 1-h group) 4 to 5 h before necropsy. The trachea and microdissected bronchi (fourth and ninth generations) and respiratory bronchioles (fifteenth generation) from the right upper lobe of each monkey were examined by electron microscopy. Labeled neutrophil influx into lung tissue and bronchoalveolar lavage fluid (BALF) was maximal at 12 h and returned to baseline by 24 h after exposure. This was in contrast to total neutrophils (labeled and unlabeled) in BALF, which were significantly elevated through 24 h after exposure but returned to baseline by 72 h. Lavage protein was significantly elevated at 24 h after exposure but was at control levels at all other times. Morphometric observations showed epithelial necrosis at 1 and 12 h in the trachea and bronchioles but continued to be observed in significant numbers at 24 h after exposure in bronchi. A significant increase in the labeling index of epithelial cells was observed at 12 h only in bronchi. Epithelial necrosis and repair was associated with the presence of granulocytes in the epithelium and interstitium of all airway levels. However, eosinophils were maximally increased in the epithelium and interstitium of bronchi at 24 h after exposure when epithelial necrosis was maximal in these airways and when lavage protein was significantly elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Language screening in preschool Chinese children.

The incidence of language delay in Chinese preschool children was studied by a stratified proportional sampling of all 3 year olds in Hong Kong. The Developmental Language Screening Scale (DLSS) devised for use with Cantonese speaking children was used to identify children with language delay. Of 855 children sampled in the stage I screening procedure, 4%, 2.8% and 3.3% were identified as having delay in verbal comprehension, expression or both respectively. The stage II clinical diagnostic study included a randomly selected group of children screened in stage I with or without any associated behavioural problem. Among these, 3.4% were identified as having a language delay using the Reynell Language Developmental Scale (RDLS) with a criterion of language age of less than or equal to two-thirds of the chronological age; 3% had specific language delay using the criteria of language age less than or equal to two-thirds the chronological age and developmental age more than or equal to two-thirds the chronological age. More boys were found to have language delay, although this was not statistically significant.

Child, Preschool↗
PubMed1991

Brainstem auditory evoked potential study in children with autistic disorder.

Brainstem auditory evoked potentials were compared in 109 children with infantile autism, 38 with autistic condition, 19 with mental retardation, and 20 normal children. Children with infantile autism or autistic condition had significantly longer brainstem transmission time than normal (p less than .001). Autistic features, rather than age, sex, or lower mentality, correlated with brainstem transmission time (p less than .0001). The autistic characteristics may be related to dysfunction of the brainstem which affects the processing of the sensory input through the auditory pathway. The brainstem lesion may be part of a generalized process of neurological damage that accounts for the deviant language, cognitive, and social development in the spectrum of autistic disorder.

Autistic Disorder↗
PubMed1991

Recombinant human and rat ciliary neurotrophic factors.

The human ciliary neurotrophic factor (CNTF) gene was identified and cloned, based on homology with the recently cloned rat cDNA. The gene encodes a protein of 200 amino acids, which shares about 80% sequence identity with rat and rabbit CNTF and, like these homologues, lacks an apparent secretion signal sequence. The human CNTF gene, like the rat gene, appears to contain a single intron separating two protein coding exons. An intronless human CNTF gene was constructed by the use of polymerase chain reactions and introduced into vectors designed for expression of foreign proteins in E. coli. The rat CNTF gene was also introduced into similar vectors. Both the human and rat proteins were expressed at exceptionally high levels, at 20-40% and 60-70% of total protein, respectively. Extraction of the recombinant proteins from inclusion bodies by guanidinium chloride, followed by two column chromatography steps, produced high yields of pure CNTF that supported survival and neurite outgrowth from embryonic chick ciliary neurons in culture. The biological activity of both recombinant proteins was comparable to that of native rat CNTF.

Amino Acid Sequence↗
PubMed1990

Lymphocyte subset alterations in nodes regional to human melanoma.

The lymphocyte subpopulations in tumor-draining lymph nodes of melanoma patients were determined using two-color flow cytometry. Data were analyzed according to: (a) the staging of the melanoma; (b) whether or not the nodes contained tumor; and (c) their distance from the primary tumor. Compared with Stage I patients (without metastasis), uninvolved nodes of stage II patients (with nodal metastases) had a significant decrease in helper/inducer (CD4+) T-cells (P less than 0.001), with a corresponding increase in cytotoxic/suppressor (CD8+) cells (P less than 0.001) and Leu 19+ natural killer (CD56+) cells (P less than 0.01). In some patients the presence of tumor within a node was associated with a large decrease in CD3+ total T-cells, whereas in others tumor involvement had little influence on lymphocyte phenotypes. When analyzed by distance from the primary tumor, nodes closest to tumor in Stage I patients contained a smaller percentage of CD19+ B-cells. In Stage II, tumor-free nodes nearest to tumor showed an increase in CD19+ cells, but statistical significance was not reached. CD56+ natural killer cells increased progressively in nodes near tumor and were more numerous in Stage II uninvolved nodes compared with Stage I nodes. Alterations in phenotypically defined lymph node lymphocytes occur in nodes regional to melanoma as the disease progresses, as growth of metastases occurs, and in tumor-free nodes nearest to tumor. These alterations may be essential to the establishment and progression of metastases.

Adult↗
PubMed1990

Regulation of cholinergic expression in cultured spinal cord neurons.

Factors regulating development of cholinergic spinal neurons were examined in cultures of dissociated embryonic rat spinal cord. Levels of choline acetyltransferase (CAT) activity in freshly dissociated cells decreased rapidly, remained low for the first week in culture, and then increased. The decrease in enzyme activity was partially prevented by increased cell density or by treatment with spinal cord membranes. CAT activity was also stimulated by treatment with MANS, a molecule solubilized from spinal cord membranes. The effects of MANS were greatest in low-density cultures and in freshly plated cells, suggesting that the molecule may substitute for the effects of elevated density and cell-cell contact. CAT activity in ventral (motor neuron-enriched) spinal cord cultures was similarly regulated by elevated density or treatment with MANS, whereas enzyme activity was largely unchanged in mediodorsal (autonomic neuron-enriched) cultures under these conditions. These observations suggest that development of cholinergic motor neurons and autonomic neurons are not regulated by the same factors. Treatment of ventral spinal cord cultures with MANS did not increase the number of cholinergic neurons detected by immunocytochemistry with a monoclonal CAT antibody, suggesting that MANS did not increase motor neuron survival but rather stimulated levels of CAT activity per neuron. These observations indicate that development of motor neurons can be regulated by cell-cell contact and that the MANS factor may mediate the stimulatory effects of cell-cell contact on cholinergic expression.

Animals↗
PubMed1990

Translational regulation of somatostatin in cultured sympathetic neurons.

Coculture of sympathetic neurons with ganglion nonneuronal cells elevated levels of preprosomatostatin mRNA but did not alter neuronal synthesis, content, or release of somatostatin. Treatment of sympathetic neurons with culture medium conditioned by exposure to ganglion nonneuronal cells similarly elevated preprosomatostatin mRNA. Treatment with conditioned medium elevated somatostatin levels in pure neuronal cultures, but not in neurons cocultured with nonneuronal cells. Conditioned medium also failed to increase peptide levels in neurons cultured on a substratum of killed nonneuronal cells, despite a large increase in preprosomatostatin mRNA. These observations suggest that contact of sympathetic neurons with nonneuronal cell membranes inhibits the increase in peptide synthesis, but not the increase in preprosomatostatin mRNA after treatment with conditioned medium. Thus neuronal interactions with nonneuronal cells regulate somatostatin metabolism at both the mRNA and peptide levels. Regulatory effects on the mRNA and the peptide are separable and do not necessarily occur in parallel, and translational controls may be the rate-limiting factors.

Animals↗
PubMed1990

Immunogenicity of Haemophilus influenzae type B vaccines in children with hepatoportoenterostomies.

To assess the immunogenicity of HIB vaccines in patients in whom hepatoportoenterostomies were performed for biliary atresia, eight such children received Haemophilus influenzae type b-polyribosylribitol phosphate (HIB-PRP) vaccine and had pre- and postvaccination total serum anti-PRP antibody concentrations determined by radioimmunoassay. Preimmunization anti-PRP antibody levels ranged from less than 0.125 to 0.40 microgram/ml [geometric mean antibody titer (GMT) 0.106 microgram/ml], while postvaccination levels ranged from 0.161 to 1.192 micrograms/ml (GMT = 0.489 microgram/ml). Five children who did not achieve postimmunization anti-PRP antibody levels greater than 1.0 microgram/ml received 15 micrograms of either PRP coupled to diphtheria toxoid (PRP-D) or PRP coupled to an outer membrane protein complex of Neisseria meningitidis group B (PRP-NOMP) conjugate vaccine. Anti-PRP antibody levels 1 month after immunization with HIB conjugate vaccines ranged from 1.51 to 10.35 micrograms/ml (GMT = 3.386 micrograms/ml). Patients with extrahepatic biliary atresia and hepatoportoenterostomies who previously received the HIB-PRP vaccine should be revaccinated with PRP protein conjugate vaccines to ensure adequate protection against H. influenzae type b disease.

Antibody Formation↗
PubMed1990

Cerebral thrombosis in beta-thalassemia/hemoglobin E disease.

We describe two Chinese patients with beta-thalassemia/hemoglobin E disease who developed cerebral infarction due to occlusion or stenosis of their extracranial carotid arteries. The roles of platelet abnormalities and other factors in this condition are discussed.

Adult↗
PubMed1990

Narcolepsy in a young Chinese child.

Narcolepsy is characterized by narcoleptic sleep attacks, cataplexy, sleep paralysis and hypnagogic hallucinations. It is very rare in children. A 7-year old Chinese boy presenting with typical narcoleptic symptoms is reported. Diagnosis of narcolepsy usually relies on the clinical picture, the presence of sleep-onset REM periods on nocturnal polysomnograph and the Multiple Sleep Latency Test. The strong association with HLA-DR2 may help in diagnosis, especially in children.

Child↗
PubMed1989

An unusual complication of an open-head injury: coccidioidal meningitis.

A case of coccidioidal meningitis following an open-head injury is presented. A 6-year-old boy was ejected from a motor vehicle as it was driven over a cliff, resulting in a severe open-skull fracture with grossly contaminated wounds. The accident occurred in an area in which coccidioidomycosis is endemic, and the causative agent, Coccidioides immitis, is found in high concentration in the soil. In addition to fracture reduction, the child received a course of intrathecal and intravenous amphotericin and achieved a satisfactory clinical response.

Amphotericin B↗