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Biomedical subjects

V Wong

Publications and source records attributed to V Wong.

At least 37 records · Page 2Linked to original sources
PubMed2001

How does alteration of hepatic blood flow affect liver perfusion and radiofrequency-induced thermal lesion size in rabbit liver?

The purpose of this study was to test the hypothesis that decreasing liver perfusion in rabbits results in an increase in thermal lesion size and that these effects can be accurately monitored using magnetic resonance imaging (MRI). We additionally tested the hypothesis that the increase in thermal lesion size would depend on the particular vessel or vessels occluded (hepatic artery, portal vein, or both). Using an Institutional Animal Care and Use Committee approved protocol, 20 New Zealand white rabbits were randomly assigned to four treatment groups (five in each group): control and ligation of portal vein (PV), hepatic artery (HA), or both PV and HA (HAPV). Surgical ligation of the appropriate vessel was performed under general anesthesia. Immediately after ligation, the rabbits were placed in a 0.2-T open MR system, and an 18-G copper radiofrequency (RF) electrode with a 2-cm exposed tip was inserted into the liver. RF was applied for 10 minutes with the tip temperature maintained at 90 degrees +/- 2 degrees C. Before and after ablation, perfusion data were obtained for 90 seconds using 30 3-second sequential single oblique-slice fast imaging with steady-state progression (FISP) acquisitions after injection of gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) via the inferior vena cava. Postablation scanning included axial and oblique turbo spin-echo (TSE) T2-weighted (T2w), STIR, and Gd-enhanced T1w sequences. Lesion size was determined perpendicular to the RF electrode using software calipers on the imager. The rabbits were sacrificed after completion of the post-therapy scans, and their livers were harvested for histologic analysis. The liver showed a mean increase in signal amplitude (SA) of 76% 24 seconds after Gd contrast injection in the control group. After contrast injection, the SA increased to a mean of only 66% in the group with ligated hepatic arteries, with no difference in the time to peak compared with the control group. No significant SA increase over baseline could be found in the groups with ligated PV or ligated PV and HA. T2-weighted images demonstrated the highest lesion-to-liver contrast-to-noise ratios (CNRs; mean -5.5) on postprocedure images, followed by STIR images (mean -2.2) in the control group. The lesions were poorly delineated on the Gd-enhanced images. Average maximum lesion sizes (mean +/- 95% confidence interval) were 22 +/- 4.3 mm after ligation of PV, 22 +/- 2.6 mm after ligation of both PV and HA, 14 +/- 2.0 mm after ligation of HA, and 13 +/- 1.9 mm in the control group. We accept the hypothesis that the diameter of the region of coagulation necrosis achieved by standardized RF ablation in the liver increases with reduced organ perfusion and that this effect can be accurately monitored using MRI. The major factor influencing the size of the coagulation area is the portal venous flow. Occlusion of the hepatic artery alone does not significantly increase lesion size. T2w sequences are best suited for postprocedure imaging due to the high lesion-to-liver CNR in rabbits with normal hepatic perfusion. J. Magn. Reson. Imaging 2001;13:57-63.

Animals↗
PubMed2001

Effect of vaginally administered fumagillin on the morphology of implantation stage endometrium in the rhesus monkey.

Intravaginal administration of an anti-angiogenic agent, fumagillin, during blastocyst implantation, inhibits pregnancy establishment in a dose-related manner in the rhesus monkey. In the present study, mated female rhesus monkeys were vaginally inserted with tampons containing vehicle (group 1; n = 5) and test agent (fumagillin, 4 mg/animal; group 2; n = 6) on cycle day 20, and endometrial tissue samples were collected on cycle day 24 from all monkeys and processed for morphometric and ultrastructural analysis. Concentrations of estradiol-17beta, progesterone and chorionic gonadotrophin in peripheral circulation were determined. From serum profiles of hormones, two monkeys in group 1, and one animal in group 2 appeared pregnant. Endometrial morphology revealed histologic evidence of pregnancy in three of six fumagillin-treated animals, while other three fumagillin-treated animals showed degenerative changes in glands and venules along with marked extravasation. It is possible that the function of corpus luteum was affected by fumagillin treatment resulting in inadequate progesterone production (p <0.05), and consequent inadequate endometrial secretory preparation and receptivity, as revealed from decline in apical movement of vacuoles (p <0.05) and increase (p <0.05) in extravasation of red cells and leukocytes.

Administration, Intravaginal↗
PubMed2001

Effect of vaginally administered (Ala(8,13,18))-magainin II amide on the morphology of implantation stage endometrium in the rhesus monkey (Macaca mulatta).

Intravaginal administration of an anti-microbial agent, (Ala(8,13,18))-magainin II amide, during blastocyst implantation inhibits pregnancy establishment in a dose-related manner in the rhesus monkey (Macaca mulatta). In the present study, mated female rhesus monkeys were vaginally inserted with tampons containing vehicle (Group 1; n = 5) and test agent (magainin, 0.5 mg/animal; Group 2; n = 6) on cycle day 20. Endometrial tissue samples were collected on Cycle Day 24 from all monkeys and processed for morphometric and ultrastructural analysis. Concentrations of estradiol-17beta, progesterone, and chorionic gonadotrophin in peripheral circulation were determined, which revealed that two monkeys in Group 1 were pregnant while no animals were pregnant in Group 2. Endometrial morphology, however, revealed histologic evidence of pregnancy in three out of the six magainin-treated animals. It appears that intra-vaginal administration of magainin II amide had a marginal effect on the implantation stage endometrium and the initiation of the implantation process in the rhesus monkey.

Administration, Intravaginal↗
PubMed2001

West syndrome--The University of Hong Kong experience (1970-2000).

OBJECTIVE: To study the clinical pattern of West syndrome (WS) in a university based hospital. METHODOLOGY: The database of children seen in the Epilepsy Clinic of Queen Mary Hospital and Duchess of Kent Children's Hospital during a 30-year period (1970-2000) was reviewed. RESULTS: A total of 105 cases had WS (1.9%). The number of new cases of WS admitted per year ranged from one to eight. The range of annual incidence of WS to newly diagnosed epilepsy was 0.8-4.8%. The etiology included idiopathic (N=19, 18%), cryptogenic (N=23; 22%), symptomatic (N=56; 53.3%) and unknown (N=7; 5.7%). Adrenocorticotropic hormone (ACTH) and/or prednisone were given to 42 children (40%). Most were effective in controlling WS on an all-or-none fashion. Seizure outcome included 12 with remission, persistent in the same form in two and persisting but changed to another form in the rest. Neurological outcome at the last follow up in 2000 December included multiple disabilities (N=16), cerebral palsy (N=22), mental retardation (N=94) and Lennox-Gastaut syndrome (N=13). We analysed the following risk factors in relation to poor outcome: age of onset, age of presentation, time lag before treatment, etiology, family history of epilepsy and hormonal treatment. Only etiology of WS has a positive correlation with poor outcome (P<0.0005). CONCLUSIONS: WS is an uncommon epileptic syndrome. The majority had poor outcome, especially those with causes identified. Infantile spasm is a specific epileptic phenomenon in a maturational stage of a child when heterogeneous disorders can present with the same clinical epileptic and electroencephalographic phenomenon.

Anticonvulsants↗
PubMed2001

Neurologic complications due to catheterization.

In our university cardiac center, the incidence of a cohort of children with acute neurologic complications resulting from cardiac catheterization performed for acyanotic or cyanotic congenital heart disease is 0.38% (14 children of a total of 3,648 catheterization procedures). Neurologic complications consisted of convulsion (n = 10), stroke (n = 6), intracranial hemorrhage (n = 2), extrapyramidal features (n = 1), paraplegia (n = 1), visual impairment (n = 1), hearing impairment (n = 1), and brachial plexus injury (n = 1). The main risk factors included prolonged duration of catheterization procedure and interventional manipulation in addition to cardiac catheterization. The possible mechanisms causing brain injury included cerebral embolism from local clots and hypoxia resulting from complications during the procedure. Other complications included intracranial hemorrhage secondary to anticoagulation and peripheral plexopathy because of prolonged fixed posture during anesthesia. The prognosis for the majority of patients with stroke is good. Neurologic sequelae, such as global developmental delay or epilepsy, occurred in those with hypoxic-ischemic encephalopathy.

Acute Disease↗
PubMed2001

Traditional Chinese medicine (tongue acupuncture) in children with drooling problems.

Tongue acupuncture is an innovative technique in traditional Chinese medicine. We have demonstrated that specific tongue acupoints are related to various functional domains. This study aimed to assess the efficacy of tongue acupuncture in children with neurologic disability who had severe drooling problems. We conducted an intent-to-treat study in a cohort of 10 children. A continuous course of tongue acupuncture was performed daily to five acupoints in the tongue for a total of 30 sessions. Standardized outcome measures of drooling were evaluated by a blinded assessor to study the efficacy at baseline and after a course of treatment. Statistically significant improvement was noted in the following outcome measures: (1) mean visual analog scale (VAS) decreased from 6.6 (pre-TAC) to 4.67 (post-TAC) (P = 0.002); (2) mean drooling quotient (DQ) decreased from 14.016% (pre-TAC) to 8.335% (post-TAC) (P = 0.0078); and (3) mean drooling score (DS) decreased from 7.4 (pre-TAC) to 4.4 (post-TAC) (P = 0.002). This study demonstrated the efficacy of tongue acupuncture as an adjunctive or alternative treatment for patients with drooling problems and can be integrated as part of the oromotor stimulation program, drooling program, and behavioral modification program before subjecting the patient to invasive surgical procedures on the salivary glands.

Acupuncture Therapy↗
PubMed2001

Ultrasonographic measurement of subarachnoid space in normal infants and children.

This study was undertaken to evaluate the sonographic measurement of subarachnoid spaces in normal children and its relationship with age and to define a normal range in a Chinese population and to differentiate normal variant findings from pathologic dilatation. The subarachnoid spaces in 278 normal term neonates, infants, and children were studied with real-time ultrasound using a 7.5-MHz vector transducer. The craniocortical width, sinocortical width, and interhemispheric width were measured in the coronal plane at the level of the foramen of Monro, on either side of the hemispheres. Correlation of sonographic measurements with age was made. The mean widths were plotted against age. A correlation with age was found in all three spaces, with an increasing trend with age until 28 weeks of gestation. Thereafter, a decreasing trend was noted. The normal upper limit of subarachnoid spaces for children is proposed to be the values on the ninety-fifth percentile of the regression curve. Correlation of measurement with age must be considered to decide whether an increase in subarachnoid space is pathologic or not.

Cephalometry↗
PubMed2001

Novel (4-piperidin-1-yl)-phenyl sulfonamides as potent and selective human beta(3) agonists.

A series of novel (4-piperidin-1-yl)-phenyl sulfonamides was prepared and evaluated for their biological activity on the human beta(3)-adrenergic receptor (AR). Replacement of the 3,4-dihydroxyl group of the catechol moiety with 4-hydroxyl-3-methyl sulfonamide on the left-hand side of the compounds resulted in a number of potent full agonists at the beta(3) receptor. Modification of the right-hand side of the compounds by incorporation of a free carboxylic acid resulted in a few potent human beta(3) agonists with low affinities for beta(1)- and beta(2)-ARs. N-Alkyl substitution on the 4-piperidin-1-yl-phenylamine further increased the beta(3) potency while maintaining the selectivity. For example, sulfonamide 48 is a potent full beta(3) agonist (EC(50)=0.004 microM, IA=1.0) with > 500-fold selectivity over beta(1)- and beta(2)-ARs.

Adrenergic beta-3 Receptor Agonists↗
PubMed2001

High-quality, cost-effective strategy for detection of autoantibodies to extractable nuclear antigens.

We evaluated methods for the detection of autoantibodies to extractable nuclear antigens (ENAs) to determine the strategy that yielded the most cost effective and clinically meaningful result. We prospectively compared counterimmunoelectrophoresis (CIEP) with and without serum prediffusion (SPD) and found that SPD significantly improved the quality of precipitation lines. This resulted in a decreased requirement for repeat testing and, consequently, was associated with a significant decrease in reagent costs and specimen turnaround time. We also retrospectively compared reactivity by CIEP, CIEP plus SPD, enzyme-linked immunosorbent assay (ELISA), and line immunoassay (LIA) of 52 serum samples that were previously determined to be positive for ENAs, and we correlated the results with clinical diagnoses. There was significant agreement among CIEP, CIEP plus SPD, ELISA, and LIA for the detection of anti-SS-A, anti-SS-B and anti-RNP. In general, CIEP, CIEP plus SPD, and LIA correlated better with the clinical diagnoses than ELISA, even though ELISA detected anti-ENAs more often than the other methods. CIEP plus SPD is therefore the most cost effective method for the identification of clinically meaningful ENAs. Based on our experience, we now screen for ENAs by CIEP, and positive samples are then typed by CIEP plus SPD. Samples that are difficult to interpret are then further assessed by an alternative method.

Antigens, Nuclear↗
PubMed2001

Neuroepithelial bodies in mammalian lung express functional serotonin type 3 receptor.

Serotonin (5-HT) type 3 receptor (5-HT(3)-R) is a ligand-gated ion channel found primarily in the central and peripheral nervous system. We report expression and functional characterization of 5-HT(3)-R in pulmonary neuroepithelial body (NEB) cells. Using nonisotopic in situ hybridization, we demonstrate expression of 5-HT(3)-R mRNA in NEB cells in the lungs of different mammals (hamster, rabbit, mouse, and human). Dual immunocytochemistry (for 5-HT and 5-HT(3)-R) and confocal microscopy localized 5-HT(3)-R on NEB cell plasma membrane from rabbit. The electrophysiological characteristics of 5-HT(3)-R in NEB cells were studied in fresh slices of neonatal hamster lung using the whole cell patch-clamp technique. Application of the 5-HT (5-150 microM) and 5-HT(3)-R agonist 2-methyl-5-HT (5-150 microM) induced inward currents in a concentration-dependent manner. The 5-HT-induced current was blocked (76.5 +/- 5.9%) by the specific 5-HT(3)-R antagonist ICS-205-930 (50 microM), whereas katanserin and p-4-iodo-N-(2-[4-(methoxyphenyl)-1-piperazinyl]ethyl)-N-2-pyridinylbenzamide had minimal effects. Forskolin had no effect on desensitization and amplitude of the 5-HT-induced current. The reduction of Ca(2+) and Mg(2+) in the extracellular solution enhanced the amplitude of the 5-HT-induced current because of slower desensitization. Our studies suggest that 5-HT(3)-R in NEB cells may function as an autoreceptor and may potentially be involved in modulation of hypoxia signaling.

Aminopyridines↗
PubMed2001

Molecular genetic study of a childhood form of spinal muscular atrophy.

Molecular genetic studies were performed in 28 cases of childhood-onset spinal muscular atrophy (24 unrelated families). This consisted of type 1 (severe) (n = 5), type 2 (intermediate form) (n = 8), and type 3 (mild) (n = 15). Deletion of exons 7 and 8 of the SMNt gene was found in 100%, 100%, and 93%, respectively, in type 1, 2, and 3 spinal muscular atrophy. Deletion of exons 5 and 6 of the NAIP gene was found in 3 of 5 (60%) of type 1 and none of the type 2 and 3 cases. None of the 32 asymptomatic relatives had homozygous deletions in the SMNt and NAIP genes. Thus, the role of the NAIP gene needs to be specifically defined in spinal muscular atrophy. In a suspected case of spinal muscular atrophy, deletion of the SMNt gene is a useful laboratory marker for confirmation of the diagnosis.

Adolescent↗
PubMed2001

Acute gastroenteritis-related encephalopathy.

We studied the incidence of convulsions in 1936 children with acute gastroenteritis. Sixty-eight children had convulsions (3.5%), which were categorized into three groups: (1) bacterial (n = 13; 19%), (2) Rotavirus (n = 30, 44%), and (3) no organism (n = 25; 37%). Only group 2 versus group 3 had a significant association with encephalopathy (P < .002). The relative risk was estimated to determine the risk of encephalopathy: Rotavirus versus no organism isolated (relative risk = 2.308), Rotavirus versus bacterial (relative risk = 1.846), and bacterial versus no organism (relative risk = 1.25). None developed epilepsy. Thus, acute gastroenteritis-related encephalopathy is a benign condition with single or recurrent seizures during an episode of acute gastroenteritis and an excellent prognosis. The underlying mechanism for provoking seizure is unknown. One should be reassured of a good outcome in the majority of children with recurrent episodes of afebrile/febrile seizures during an episode of acute gastroenteritis.

Acute Disease↗
PubMed2000

Involvement of p38 mitogen-activated protein kinase in the induction of tolerance to hemorrhagic and endotoxic shock.

BACKGROUND: Exposure to sublethal hemorrhage (SLH) makes rats tolerant to subsequent hemorrhagic or septic shock and is associated with altered NF-kappaB activity. The purpose of this study was to explore whether changes in p38 mitogen-activated protein (MAP) kinase activity also occur in the induction of tolerance by SLH. METHODS: Rats were made tolerant by SLH or sham operation. Twenty-four hours later rats were exposed to lipopolysaccharide (LPS) or had peritoneal macrophages (Mphi) isolated. CNI-1493, a p38 MAP kinase inhibitor, or saline was given prior to SLH. Lungs were harvested 1 h after SLH or LPS and total protein was extracted. Peritoneal Mphi were stimulated with LPS (10 microg/ml) and total protein was isolated 1 h later. Active, dually phosphorylated p38 MAP kinase was determined by Western blot. Tumor necrosis factor (TNF) was measured in Mphi supernatants by enzyme-linked immunosorbent assay (ELISA) 18 h after LPS. RESULTS: SLH activated p38 MAP kinase in the lung and this was inhibited by CNI-1493. Twenty-four hours later, lung p38 MAP kinase activity increased to the same degree in tolerant and sham rats following LPS, but much more prominently in the CNI-1493 treated rats. There was no p38 activity in peritoneal Mphi at baseline, and similar to lung p38, LPS led to increased p38 activity which was most significant in Mphi from rats that received CNI-1493 prior to SLH. TNF production by tolerant Mphi in response to LPS was significantly (P < 0.05, t test) decreased and p38 inhibition with CNI-1493 at the time of SLH reversed the inhibitory effects of tolerance on TNF production. CONCLUSIONS: TNF production by tolerant Mphi following a second insult (LPS) is attenuated despite preservation of normal p38 MAP kinase activity. However, activation of this intracellular second messenger is a necessary step in the "cellular reprogramming" that occurs during the induction of tolerance by SLH.

Adaptation, Physiological↗
PubMed2000

Spectrum of epileptic syndromes with electrical status epilepticus during sleep in children.

There has been much debate about the nosologic forms of electrical status epilepticus during sleep (ESES) that can occur in a number of syndromes. The pathogenesis of ESES is unknown, and the natural course is variable. It is debatable whether these age-specific epileptic syndromes belong to the same spectrum of disorders with different severity but a common denominator of sleep-related hypersynchronization of generalized paroxysmal epileptic discharges. This report describes 18 children with medically refractory seizures, gradual deterioration in language skills, fine-motor incoordination, behavioral changes, psychologic and intellectual regression of different degrees, and the ESES phenomenon. Most exhibited clinical and electroencephalographic responses to intravenous or oral benzodiazepines, especially if initiated within the first 2 years of seizure onset. Seizure remission was nearly complete with cessation of seizures and marked improvement in language and fine-motor skills, behavior, and intellectual function in those with an idiopathic etiology. Therapeutic trials with benzodiazepines should be given to all children with the ESES phenomenon. Sleep electroencephalographic monitoring is recommended in all young children with epilepsy and language or psychologic deterioration so that the brain dysfunction can be reversed at a critical and vulnerable period of early life.

Adolescent↗
PubMed2000

Isolation and characterization of an antigenically distinct 68-kd protein from nonviral intracytoplasmic inclusions in Boa constrictors chronically infected with the inclusion body disease virus (IBDV: Retroviridae).

The relationship between a retroviral infection and the development of nonviral intracytoplasmic inclusion bodies was studied in a Boa constrictor model. Twelve juvenile age- and size-matched inclusion body disease (IBD)-negative boas were randomly divided into three groups. Each group was inoculated intraperitoneally with 1 ml of an IBD virus (IBDV)-infected liver homogenate or 1 ml of normal boa liver homogenate (sham-inoculated control) or was left untreated. All boas were monitored for development of IBD by daily examination and serial liver biopsy over 1 year. The 4 IBDV-inoculated boas became IBDV and inclusion positive by 10 weeks postinoculation. The average size and density of inclusion bodies increased with the duration of infection. Ultrastructurally, inclusion bodies <2 microm in diameter consisted of intracytoplasmic aggregates of granular electron-dense material that were not membrane limited. Larger inclusions (3-6 microm in diameter) were characterized as membrane-bound aggregates of amorphous to granular electron-dense material admixed with membranelike fragments. The sham-inoculated and untreated control snakes did not become inclusion or IBDV positive. Direct comparison of the protein electrophoretograms of IBDV-infected and normal boa tissues demonstrated a prominent 68-kd protein band unique to infected inclusion-positive tissues. Monoclonal antibodies directed against the 68-kd protein band specifically labeled inclusion bodies. The results of this study demonstrate that IBD inclusions represent an intracytoplasmic accumulation of an antigenically distinct IBDV-associated protein.

Animals↗
PubMed2000

Parental history of alcoholism and problem behaviors in Native-American children and adolescents.

BACKGROUND: A positive family history of alcoholism is one of the most consistent and powerful predictors of a person's risk for developing this disorder. This finding has stimulated much research on etiological vulnerability factors and mechanisms by which children of alcoholic parents are at high risk for developing alcohol-related problems. In primarily Euro-American samples, parental alcoholism has been associated with a variety of negative outcomes for children and adolescents, including problematic behavior. Native-American Indians, in addition to high rates of alcoholism and alcohol-related mortality, have the highest prevalence of a positive family history for alcoholism of all ethnic groups in the United States. METHODS: This study used the Achenbach Child Behavior Checklist (CBCL) to evaluate behavioral problems in 96 Mission Indian children and adolescents based on the presence or absence of parental alcohol dependence and sex of the offspring. RESULTS: Consistent with previous research, results indicated a high prevalence of a positive family history of alcoholism in these Native-American youths. Seventy-four percent of the offspring had either one or both parents with alcohol dependence (children of alcoholics). Only 7% had no first- or second-degree alcoholic relatives. Results indicated that sons of alcoholics scored significantly higher on the Total Behavior Problem scale, as well as the Internalizing and Externalizing scales, of the CBCL than sons of nonalcoholics, whereas there were no significant differences in CBCL scores between daughters of alcoholics and daughters of nonalcoholics. It is noteworthy that scores on the CBCL for Mission Indian children of alcoholics were comparable to scores in the published literature of children of alcoholics of other ethnicities. In addition, a relatively low percentage of youths were identified with significant levels of behavioral problems. CONCLUSIONS: These findings suggest that sons of alcoholics of Mission Indian heritage experience more problems than sons of nonalcoholics, but also suggest that Mission Indian children of alcoholics are not more vulnerable to behavioral problems than children of alcoholic parents of other ethnic backgrounds.

Adolescent↗