Biomedical subjects

V Wong

Publications and source records attributed to V Wong.

At least 73 records · Page 4Linked to original sources

PubMed1998

Use of botulinum toxin injection in 17 children with spastic cerebral palsy.

The use of botulinum toxin was studied in 17 children with spastic cerebral palsy to determine its efficacy and tolerability. Eleven ambulatory and 6 nonambulatory patients were included. All children were undergoing a physiotherapy program with monitoring of their baseline states for 3 months before botulinum toxin injection. The effect was evident within 72 hours. The peak effect was noticed by 1 to 2 weeks in the majority; the effect lasted for 3 to 10 months. All children experienced decreased spasticity scores. Their functional status improved, with three nonambulatory children becoming ambulatory with assistance and five children with assisted ambulation becoming more independently ambulatory. Measurement of joint motion showed improvement in the range of motion as compared with baseline. Video analysis of the functional state in the nonambulatory or gait in the ambulatory children revealed improvement in all. The functional status of rising from the sitting position or standing demonstrated improvement. None of the children had any untoward side effects except mild transient pain at the injection site. This study demonstrated botulinum toxin is useful as an adjunctive therapy in ameliorating spasticity in children with cerebral palsy, especially in the younger ones.

Activities of Daily Living↗

PubMed1998

Brainstem auditory-evoked potential evaluation in children with meningitis.

Brainstem auditory-evoked potential (BAEP) was performed on 101 children with meningitis to assess the incidence of hearing impairment. Fifty-two (51.5%) children had bacterial meningitis, six (5.9%) had viral meningitis, and 43 (42.6%) had aseptic meningitis. Fifty-one (50.5%) patients were assessed before discharge and 50 (49.5%) 9 days to 17 months later (mean = 4 months). BAEP impairment was found in 28 (27.7%) of 101 patients; 24 had sensorineural and four had conductive type of hearing loss, and 17 (60.7%) had unilateral and 11 (39.3%) had bilateral impairment. Hearing threshold was elevated in 22 (21.8%) patients, and the other six had increased latency and interpeak latencies with normal threshold. Frequency of BAEP impairment or hearing loss associated with bacterial meningitis was 34.6% and 30.8%, respectively; frequency associated with aseptic meningitis was 20.9% and 13.9%, respectively. One child with viral meningitis (coxsackie virus) had mild BAEP impairment. Most of the BAEP impairment in the bacterial meningitis group was associated with H. influenzae. Prospective BAEP study was performed in 20 patients randomly at 0.3 to 18 months to assess hearing status after antibiotic treatment, 10 with normal and 10 with abnormal BAEP. All the initially normal BAEP patients remained normal. Of the 10 patients with abnormal BAEP results initially, four returned to normal, two improved, three remained unchanged, and one deteriorated. The incidence of hearing loss after bacterial and aseptic meningitis is high. BAEP is useful to screen for possible hearing loss in children with meningitis, and follow-up BAEP is necessary for those patients with initially abnormal BAEP.

Child↗

PubMed1998

DNA diagnosis of FRAXA and FRAXE in Chinese children with neurodevelopmental disorders and fragile X syndrome.

Fragile X (FraX) syndrome is the most common cause of inherited mental retardation. To see whether FRAXA or FRAXE can account for the etiology of some unexplained neurodevelopmental disorders in children, we screened for trinucleotide repeat expansion in a consecutive cohort of 73 Chinese children and their mothers seen in 1995 (group 1) referred for developmental assessment due to developmental delay, language delay, attention deficit hyperactivity disorder, autistic spectrum disorder, mental retardation and/or learning disability. We also screened DNA samples of all five previously diagnosed cytogenetically-positive FraX boys, their mothers and sisters (group 2). A control group of unrelated teenagers and adults were recruited from the community (group 3). In group 1, 3 families (2 mothers and a mother and her son) were found to carry a small premutation allele at FRAXA (premutation frequency = 2%, 3/153 independent X chromosomes), but none had any expansion at FRAXE. In group 2, all 5 FraX boys had full mutation at FRAXA and normal repeat length at FRAXE. In group 3, 1 male has a premutation allele out of 18 males and 59 females tested (premutation frequency of control = 0.7%, 1 out of 136 X chromosomes). For FRAXE screening in group 3, 2 females were carriers (1.5%, 2 out of 136 X chromosomes). Thus, FRAXA and FRAXE cannot account for the etiology of neurodevelopmental disorders in our cohort of Chinese children, and the prevalence of FRAXE mutation in normal Chinese population appears to be higher than reported in the Caucasians.

Adult↗

PubMed1998

Relationship of inhaled ozone concentration to acute tracheobronchial epithelial injury, site-specific ozone dose, and glutathione depletion in rhesus monkeys.

Acute pulmonary epithelial injury produced by short-term exposure to ozone varies by site within the tracheobronchial tree. To test whether this variability is related to the local dose of ozone at the tissue site or to local concentrations of glutathione, we exposed adult male rhesus monkeys for 2 h to filtered air or to 0.4 or 1.0 ppm ozone generated from 18O2. Following exposure, lungs were split into lobes and specimens were selected by microdissection so that measurements could be made on airway tissue of similar branching history, including trachea, proximal (generation one or two) and distal (generation six or seven) intrapulmonary bronchi, and proximal respiratory bronchioles. One half of the lung was lavaged for analysis of extracellular components. In monkeys exposed to filtered air, the concentration of reduced glutathione (GSH) varied throughout the airway tree, with the proximal intrapulmonary bronchus having the lowest concentration and the parenchyma having the highest concentration. Exposure to 1.0 ppm ozone significantly reduced GSH only in the respiratory bronchiole, whereas exposure to 0.4 ppm increased GSH only in the proximal intrapulmonary bronchus. Local ozone dose (measured as excess 18O) varied by as much as a factor of three in different airways of monkeys exposed to 1.0 ppm, with respiratory bronchioles having the highest concentration and the parenchyma the lowest concentration. In monkeys exposed to 0.4 ppm, the ozone dose was 60% to 70% less than in the same site in monkeys exposed to 1.0 ppm. Epithelial disruption was present to some degree in all airway sites, but not in the parenchyma, in animals exposed to 1.0 ppm ozone. The mass of mucous and ciliated cells decreased in all airways, and necrotic and inflammatory cells increased. At 0.4 ppm, epithelial injury was minimal, except in the respiratory bronchiole, where cell loss and necrosis occurred, and was 50% that found in monkeys exposed to 1.0 ppm ozone. We conclude that there is a close association between site-specific O3 dose, the degree of epithelial injury, and glutathione depletion at local sites in the tracheobronchial tree.

Animals↗

PubMed1997

Immunocytochemical localization on O2-sensing protein (NADPH oxidase) in chemoreceptor cells.

A potential candidate for an oxygen-sensing protein in chemoreceptor cells is a heme-linked multicomponent NADPH oxidase, originally described in neutrophils. The postulated function for the oxidase in chemoreceptor cells is to signal changes in oxygen levels (either in the blood or in the airway lumen) via changes in oxygen metabolite production. An alteration in either superoxide (or dismuted hydrogen peroxide) production may affect the gating properties of the O2-sensitive K+ channels. We have previously reported immunohistochemical localization of gp91 glycoprotein component of the oxidase to the plasma membrane of pulmonary neuroepithelial body (NEB) cells. In this study we have investigated the immunocytochemical localization of the other polypeptide components of the oxidase in NEB cells and in the glomus cells of the carotid body. Cultures of dissociated fetal rabbit NEB cells and newborn rat glomus cells were immunostained with specific antibodies recognizing the various polypeptide subunits of the oxidase using indirect immunofluorescence methods. Immunostaining with the anti-oxidase antibodies reveal strong positive reaction in both NEB and glomus cell clusters while other cells were unstained. The positive reaction product was localized to the plasma membrane and/or cytoplasm and no nuclear staining was observed. Live cell labelling studies with anti-p22 antibody showed positive immunofluorescence on the surface of NEB cells, suggesting that this component of the oxidase is also associated with the plasma membrane. In glomus cells, similar strongly positive immunofluorescence signal was observed for p22 and gp91 in paraformaldehyde-fixed cultures, regardless whether they were permeabilized or not. Taken together, our findings of cell surface localization of gp91 and p22 components of the oxidase in chemoreceptive cells suggests that the heme-linked cytochrome b558 component is associated with the plasma membrane. This association allows for direct interaction with the O2-sensitive K+ channel thus forming the molecular complex of membrane bound O2 sensor.

Animals↗

PubMed1997

Hepatocyte growth factor promotes motor neuron survival and synergizes with ciliary neurotrophic factor.

Hepatocyte growth factor (HGF) has been shown to function as a potent mitogen for a variety of cells, transducing its signal through the c-met tyrosine kinase receptor. Ciliary neurotrophic factor (CNTF) is a cytokine that has been shown to promote survival of motor neurons. We show here that c-met mRNA is present in the embryonic rat spinal cord. Peak expression of c-met (at E14) coincides with the period of naturally occurring cell death in motor neurons, suggesting a possible role of HGF in the regulation of this process. Utilizing a neuron-enriched culture system, we established that HGF, like CNTF, stimulates choline acetyltransferase (CAT) activity in motor neurons. When co-administered to motor neuron cultures, saturating concentrations of HGF and CNTF produced a synergistic increase in CAT levels. We show that this synergy reflects enhanced motor neuron survival. Exposure of motor neuron cultures to the cytostatic agent vincristine markedly decreased CAT levels; co-treatment with HGF and CNTF (but not either factor alone) restored CAT activity to control levels. Our findings indicate that HGF is a survival factor for motor neurons, that it acts synergistically with CNTF, and that HGF and CNTF can together be neuroprotective in the face of vincristine toxicity.

Animals↗

PubMed1997

A synthetic peptide corresponding to the extracellular domain of occludin perturbs the tight junction permeability barrier.

Occludin, the putative tight junction integral membrane protein, is an attractive candidate for a protein that forms the actual sealing element of the tight junction. To study the role of occludin in the formation of the tight junction seal, synthetic peptides (OCC1 and OCC2) corresponding to the two putative extracellular domains of occludin were assayed for their ability to alter tight junctions in Xenopus kidney epithelial cell line A6. Transepithelial electrical resistance and paracellular tracer flux measurements indicated that the second extracellular domain peptide (OCC2) reversibly disrupted the transepithelial permeability barrier at concentrations of < 5 microM. Despite the increased paracellular permeability, there were no changes in gross epithelial cell morphology as determined by scanning EM. The OCC2 peptide decreased the amount of occludin present at the tight junction, as assessed by indirect immunofluorescence, as well as decreased total cellular content of occludin, as assessed by Western blot analysis. Pulse-labeling and metabolic chase analysis suggested that this decrease in occludin level could be attributed to an increase in turnover of cellular occludin rather than a decrease in occludin synthesis. The effect on occludin was specific because other tight junction components, ZO-1, ZO-2, cingulin, and the adherens junction protein E-cadherin, were unaltered by OCC2 treatment. Therefore, the peptide corresponding to the second extracellular domain of occludin perturbs the tight junction permeability barrier in a very specific manner. The correlation between a decrease in occludin levels and the perturbation of the tight junction permeability barrier provides evidence for a role of occludin in the formation of the tight junction seal.

Amino Acid Sequence↗

PubMed1997

Dose-related airway-selective epithelial toxicity of 1-nitronaphthalene in rats.

Nonciliated ("Clara") cells of terminal bronchioles are one of the principal targets of bioactivated pulmonary toxicants. However, we have recently observed cytotoxicity in proximal tracheobronchial airways with high doses of naphthalene. To test if this was true for other xenobiotics, 1-nitronaphthalene (25, 50, 100, or 150 mg/kg) was injected i.p. into male Sprague-Dawley rats and cytotoxicity characterized 24 hr later by high-resolution histopathology along a defined airway path extending from the trachea to the terminal bronchioles. At 25 mg/kg, only nonciliated cells in minor daughter airways were swollen and necrotic. At 50 mg/kg there was near complete loss of nonciliated cells in most bronchioles, minor daughter airways, and tracheas. Marked damage to ciliated cells was observed at doses of 100 and 150 mg/kg. Denudation of the basement membrane was common in the trachea. We conclude for 1-nitronaphthalene cytotoxicity in the lung that: (1) nonciliated cells of the distal bronchioles are not the only target, (2) the threshold for injury in nonciliated cells is lower than that for ciliated cells, (3) the response is airway selective, (4) the response is dose-related.

Animals↗

PubMed1997

Localization and neurohemal release of FMRFamide-related peptides in the stick insect Carausius morosus.

FMRFamide-like immunoreactivity was localized immunohistochemically in the central stomatogastric nervous systems, visceral tissues, and the neurohemal corpora cardiaca, transverse, and segmental nerves. Each of these neurohemal areas contains one morphologically distinct type of immunoreactive neurosecretory granule. The hemolymph level of FMRFamide-like peptides, quantified by RIA, is higher in animals sampled 2 h into the dark cycle, relative to those sampled at mid-light cycle or 9 h into the dark cycle. High potassium depolarization evokes the calcium-dependent release of FMRFamide-like peptides from neurohemal areas in vitro and HPLC fractionation of hemolymph, corpora cardiaca, and their bathing medium suggests that these organs contribute a single peptide to the FMRFamide-related peptides circulating in the hemolymph of active animals.

Animals↗

PubMed1997

A neurophysiological study in children with Miller Fisher syndrome and Guillain-Barre syndrome.

Serial neurophysiological studies were performed in four children with Miller Fisher syndrome (MFS) (n = 2) and Guillain-Barre syndrome (GBS) (n = 2) to delineate the extent of subclinical neurological involvement. Nerve conduction study showed radiculo-neuropathy in both MFS and GBS. Somatosensory evoked potential study showed evidence of peripheral and central involvement of the neural pathway in both. Brainstem auditory evoked potential study showed peripheral auditory and brainstem involvement in MFS but was normal in GBS. This study provides neurophysiological evidence that MFS and GBS might possibly belong to the clinical spectrum of encephalo-myclo-radiculo-neuropathy (EMRN) with different extent of central and peripheral involvement.

Child↗

PubMed1997

The spectrum of arthrogryposis in 33 chinese children.

The clinical profile of 33 children (19 boys, 14 girls) with multiple congenital contractures has been studied. The majority (54%) belong to arthrogryposis multiplex congenita with a static clinical course. Children were classified into three groups: group I (limb involvement only; n = 21) having arthrogryposis multiplex congenita (n = 18), distal arthrogryposis syndrome (n = 2) and Streeter syndrome (n = 1); group II (limb involvement with other malformation or anomalies; n = 7) having congenital contractural arachnodactyly (n = 3), Larsen syndrome (n = 1), multiple pterygium syndrome (n = 1), craniocarpotarsal dystrophy (n = 1), and Schwartz Jampel syndrome (n = 1); and group III (limb involvement with central nervous system dysfunction or mental retardation; n = 5) having myotonia dystrophica (n = 2), congenital muscular dystrophy (n = 1), foetal alcohol syndrome (n = 1) and Pena-Shokeir syndrome (n = 1). Three children died, one each of arthrogryposis multiplex congenita, congenital contractural arachnodactyly and myotonia dystrophica. The majority had a good prognosis with independent function and mobility.

Abnormalities, Multiple↗

PubMed1997

Ocular abnormalities in Down syndrome: an analysis of 140 Chinese children.

One hundred forty Chinese children with Down syndrome (DS) treated in the Child Assessment Centre of the Duchess of Kent Children's Hospital in Hong Kong between 1985 and 1996 underwent a detailed ophthalmologic evaluation, including test of visual acuity by behavioral testing or retinoscopy, determination of ocular motility, visual field examination, binocular examination for strabismus, determination of near point convergence and pupillary reflex, and/or slit lamp bimicroscopy and ophthalmoscopy to assess ocular health. Only 43 children (31%) had no ocular abnormalities. The overall incidence of ocular abnormalities was 69%, and included refractive error (58%), strabismus (20%), nystagmus (11%), blepharitis/conjunctivitis (7%), lens opacities (4%), and glaucoma (0.7%). No child had Brushfield spots or keratoconus. The incidence of refractive errors increased with increasing age and nearly doubled at school age. As compared with white children with DS, the Chinese children with DS exhibited a higher incidence of refractive error and a similar incidence of lens opacities but a lower incidence of strabismus, nystagmus, blepharitis, Brushfield spots, and keratoconus. Regular visual surveillance, especially of visual acuity, in children with DS as they mature is important in preventing amblyopia.

Adolescent↗

PubMed1997

Enhancement of oculomotor nerve: a diagnostic criterion for ophthalmoplegic migraine?

The oculomotor nerve of a 6-year-old boy with recurrent headache and recurrent ophthalmoplegia was contrast-enhanced on a magnetic resonance imaging (MRI) scan during an episode. The boy exhibited dramatic response to steroid treatment. The clinical features of ophthalmoplegic migraine and Tolosa-Hunt syndrome overlapped in this patient. We suggest that a positive MRI finding can be included as one of the diagnostic criteria in the classification of ophthalmoplegic migraine and that a trial of steroid is worthwhile in the presence of enhancement of the oculomotor nerve since ophthalmoplegic migraine may be noninfectious but inflammatory in etiology.

Anti-Inflammatory Agents↗

PubMed1997

Improved bioavailability and clinical response in patients with chronic liver disease following the administration of a spironolactone: beta-cyclodextrin complex.

AIMS: To compare the absorption and clinical effect of spironolactone from an inclusion complex with beta-cyclodextrin (SP-COMP) to Aldactone tablets (ALD) in chronic liver disease. METHODS: Patients, admitted with chronic liver disease, completed a randomized crossover steady state study. They received their spironolactone dose as either daily SP-COMP or ALD for 7 days. Serial blood samples were drawn over a 24 h period from day 7 of each therapy. Accurate fluid balance was recorded on days 5-7 and 12-14. Thirteen (six females) whose mean (s.d.) age and weight was 58.4(9.3) years and 74.3(19.0) kg completed the study. RESULTS: The mean (95% confidence limits) relative bioavailability for SP-COMP (compared with ALD) from steady state serum concentrations of canrenone, 6beta-hydroxyl 7alpha-thiomethyl spironolactone and 7alpha-thiomethyl spironolactone was 310.0 (265.4, 336.7), 233.4(212.9, 250.8) and 254.8(230.8, 279.0)%, respectively. Improvements in clinical status and fluid balance occurred over the last 3 days of SP-COMP with a mean (s.d.) net loss, in fluid balance, of 1370(860)ml compared with a gain of 228(936)ml during ALD. CONCLUSIONS: Better absorption of spironolactone from the spironolactone: beta-cyclodextrin complex formulation should lead to a reduction in dosage and perhaps a more consistent effect in patients with chronic liver disease.

Biological Availability↗

PubMed1997

Importance of age in chronic hepatitis C virus infection.

This study was designed to investigate the value of liver biopsy in the management of patients with chronic hepatitis C virus infection and to identify risk factors for fibrosis. It was a prospective audit of clinical, biochemical, virological and radiological features for predicting liver fibrosis in 140 consecutive patients seropositive for antibody against hepatitis C virus. Seventy-five per cent of patients were asymptomatic and 69% had no clinical signs of chronic liver disease. Serum transaminase levels were normal in 44% of patients, less than twice normal in 35% and more than twice normal in 21%. Ultrasound scan was unremarkable in 85%. Sixty-nine per cent of patients were viraemic at the time of liver biopsy. Liver histology revealed that fibrosis was absent in only 10% of patients (stage 0) while cirrhosis was evident in 7% (stage 5). Liver fibrosis was detected in 90% of patients (stage 1, 11%; stage 2, 41%; stage 3, 21%; and stage 4, 10%). Univariate analysis showed that increasing age, clinical signs of chronic liver disease and abnormal ultrasound scan findings were associated with liver fibrosis (P<0.05); however, multiple linear regression analysis of all the clinical features did not reveal a useful model (sensitivity 42% and specificity 23%) for predicting liver fibrosis. Hence, no combination of clinical, biochemical, virological or radiological data was reliable in discriminating the stage of liver fibrosis in patients with chronic hepatitis C virus infection. However, older patients, especially those with clinical signs of chronic liver disease and abnormal ultrasound scan findings, were more likely to have advanced fibrosis. We recommend liver biopsy as the single most important investigation in detecting liver fibrosis.

Adolescent↗

PubMed1997

Cutis marmorata telangiectatica congenita: an unusual presentation with monoatrophy in two Chinese children.

Cutis marmorata telangiectatica congenita (CMCT) is a rare cutaneous vascular anomaly. Two children with monoatrophy of one limb referred for neurological assessment were found to have a segmental form of CMTC. The paediatrician and paediatric neurologist should be alerted to this rare disease in children referred for cutaneous lesion with associated limb asymmetries as distinguished from other neurocutaneous syndromes.

Arm↗

PubMed1997

Suppression of grp78 core promoter element-mediated stress induction by the dbpA and dbpB (YB-1) cold shock domain proteins.

The highly conserved grp78 core promoter element plays an important role in the induction of grp78 under diverse stress signals. Previous studies have established a functional region in the 3' half of the core (stress-inducible change region [SICR]) which exhibits stress-inducible changes in stressed nuclei. The human transcription factor YY1 is shown to bind the SICR and transactivate the core element under stress conditions. Here we report that expression library screening with the core element has identified two new core binding proteins, YB-1 and dbpA. Both proteins belong to the Y-box family of proteins characterized by an evolutionarily conserved DNA binding motif, the cold shock domain (CSD). In contrast to YY1, which binds only double-stranded SICR, the Y-box/CSD proteins much prefer the lower strand of the SICR. The Y-box proteins can repress the inducibility of the grp78 core element mediated by treatment of cells with A23187, thapsigargin, and tunicamycin. In gel shift assays, YY1 binding to the core element is inhibited by either YB-1 or dbpA. A yeast interaction trap screen using LexA-YY1 as a bait and a HeLa cell cDNA-acid patch fusion library identified YB-1 as a YY1-interacting protein. In cotransfection experiments, the Y-box proteins antagonize the YY1-mediated enhancement of transcription directed by the grp78 core in stressed cells. Thus, the CSD proteins may be part of the stress signal transduction mechanism in the mammalian system.

Bacterial Proteins↗

PubMed1997

Phosphorylation of occludin correlates with occludin localization and function at the tight junction.

Multiple forms of occludin were found in Madin-Darby canine kidney (MDCK) cells. In the absence of cell-to-cell contacts achieved by incubating cells in low-calcium growth medium, a cluster of lower-molecular-weight (LMW) occludin bands (approximately 65,000-68,000) was present in both MDCK I and II cells. On formation of tight junctions, achieved by changing the low-calcium growth medium to normal-calcium growth medium, a cluster of higher-molecular-weight (HMW) bands (approximately 72,000-75,000 for MDCK I cells and approximately 70,000-73,000 for MDCK II cells) was also expressed. The HMW occludin bands could be eliminated by phosphatase treatment. Therefore, the HMW forms of occludin appeared to be the hyperphosphorylated product of the LMW forms. These HMW forms were Triton X-100 insoluble, which correlated with their localization at the tight junctions. Furthermore, depletion of tight junction-localized occludin by an occludin extracellular domian peptide (20) correlated with a decrease in the HMW forms of occludin. In conclusion, phosphorylation of occludin may be a mechanism by which occludin localization and function are regulated.

Animals↗