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Biomedical subjects

P Wong

Publications and source records attributed to P Wong.

At least 19 recordsLinked to original sources
PubMed2006

Association analysis of endothelial nitric oxide synthase gene polymorphism with primary hypertension in a Singapore population.

Vascular endothelial cells produce nitric oxide (NO), which contributes to the regulation of blood pressure and regional blood flow. Endothelial nitric oxide synthase (eNOS) gene polymorphisms are associated with coronary artery disease, but their linkage with primary hypertension is controversial. A total of 103 individuals with primary hypertension and 104 normotensive control subjects were studied in Singapore. The specific genotypes for G894T missense variant in exon 7, variable number tandem repeats (VNTR) in intron 4 (eNOS 4A/B/C) and T-786C in the promoter were isolated using allele-specific gene amplification and restriction fragment length polymorphism to examine the association of genotype and allelic frequency in both groups. Logistic regression analysis was also used to detect the association between genotypes and hypertension. Five genotypes of intron 4 VNTR (AA, AB, BB, AC and BC) were observed. Intron 4 B/B genotype was significantly associated with the hypertension group (P = 0.035), but disequilibrium of G894T and T-786C was absent between the two groups (P = 0.419 and P = 0.227), respectively. The overall distribution of allelic frequency differed significantly between the two groups, with four-repeat allele (4A) of intron 4 more frequent in the normotensive group than the hypertensive group (P = 0.019). Logistic regression analysis showed that intron 4 B/B genotype was significantly associated with systolic blood pressure of individuals with body mass index greater than 25 kg/m2 (P = 0.04). In conclusion, the eNOS 4 B/B genotype is a genetic susceptibility factor for primary hypertension in a Singapore population.

Blood Pressure↗
PubMed2006

Long term clinical outcome and bleeding complications among hospital survivors with acute coronary syndromes.

OBJECTIVE: To examine the 21 month clinical outcome and bleeding complications in hospital survivors with non-ST segment elevation acute coronary syndromes (NSTEACS) who were discharged with combined clopidogrel and aspirin anti-thrombotic therapy, and compare with those having ST segment elevation myocardial infarction (STEMI) who were discharged with aspirin alone. DESIGN: Observational study. SETTING: A large university hospital. PATIENTS: 224 patients were admitted to hospital with either NSTEACS or STEMI, and survived to discharge between 1 October 2001 and 31 December 2002. MAIN OUTCOME MEASURES: Cardiovascular death, total death, new myocardial infarction, unstable angina requiring hospitalisation, stroke or transient ischaemic attack, coronary revascularisation; and fatal, life threatening, major and minor bleeding over 21 months after discharge. RESULTS: Despite having no or small infarct (median maximum creatine kinase 155 v 1295 u/l; p<0.001) and taking more antianginal drugs, patients with NSTEACS had similar rates of cardiovascular death (9.5% v 8.3%; p = NS), new myocardial infarction (9.5% v 6.5%; p = NS) or unstable angina requiring hospitalisation (15.5% v 10.2%; p = NS) when compared with STEMI. Fatal, life threatening or major bleeding were <1% in both groups (p = NS); and minor bleeding occurred in 4.3% NSTEACS and 2.8% STEMI patients respectively (p = NS). CONCLUSIONS: Patients with NSTEACS had a similar and unfavourable long term outcome when compared with STEMI. There was no difference in serious bleeding complications between both groups.

Acute Disease↗
PubMed2006

Elderly patients are at greater risk of cytopenia during antiviral therapy for hepatitis C.

UNLABELLED: The results of antiviral therapy for hepatitis C virus (HCV) have improved recently with the use of pegylated interferon (PEG-IFN)/ribavirin (RBV) combination therapy. At this point, most patients with chronic HCV remain untreated. Thus, it is anticipated that therapy will be more appealing and prescribed more broadly than in the past, including in patients considered marginal. AIM: To examine the effects of PEG-IFN-based antiviral therapy in elderly patients with chronic HCV. METHODS: The charts of patients treated with chronic HCV were reviewed. Patients were defined as elderly if they were 60 years of age or older. The control group consisted of patients younger than 60 years of age who were matched to the treated elderly patients based on sex, treating physician, prescribed treatment and intended prescribed treatment duration. The data recorded included end of treatment response, sustained virological response (SVR), adverse events, dose modification and withdrawal of therapy. RESULTS: Thirty of 147 (20.4%) elderly patients attending a hepatitis C clinic were treated. The average age of the elderly patients was 65+/-4 years. Forty-three per cent were men and 57% were women. Ten per cent received IFN monotherapy, 70% received a combination of IFN/RBV therapy and 20% received a combination of PEG-IFN/RBV therapy. The overall response rates in the elderly patients compared with the younger patients was 46.7% versus 65.8% (P=0.11) for end of treatment response and 33.3% versus 51.2% (P=0.13) for SVR. The rate of dose modification was 50% in the elderly patients compared with 29% in the control group (P=0.08). Therapy was discontinued in 53% of the elderly compared with 34% of younger patients (P=0.17). The younger patients reported more side effects than elderly patients; although, there were more laboratory abnormalities (anemia, thrombocytopenia and neutropenia) in the elderly patients during therapy than in the younger group (0.93 per patient versus 0.49 per patient, P=0.01). CONCLUSION: Elderly patients with chronic HCV can be treated successfully. However, they are more at risk to develop cytopenias while on treatment. In such patients, the close monitoring of blood counts is necessary. Larger studies are needed to confirm these findings and to determine whether SVR differs in this population.

Adult↗
PubMed2006

Optimal evaluation of digital electroencephalograms.

Currently available digital EEG equipment provides considerably greater opportunities for clinical data analysis than is generally appreciated especially when appropriate software is used. Data from 7 different laboratories that had been obtained for routine diagnostic evaluations on 7 different EEG instruments and stored on compact disks were investigated. Since the instruments do not filter the data at input, ultra slow activity down to 0.01 Hz is currently being recorded but the attenuation factor is instrument dependent. Nevertheless, relevant clinical information is potentially available in these data and needs to be explored. Several examples in regard to epilepsy are presented. Determination of seizure onset may depend on the frequencies that are examined. The use of appropriate filter settings and viewing windows for the clinical question to be answered is stressed. Differentiation between simple and complex spike wave discharges, as well as spread of spikes, can readily be achieved by expanding the time base to 1 or 2 seconds and placing a cursor on the peak of the negative spike. Latencies in the millisecond range can then become apparent. EEGs co-registered with MEG should be evaluated with the same software in order to allow an adequate assessment of the similarities and differences between electrical and magnetic activity. An example of a comparison of EEG, planar gradiometers and magnetometers for an averaged spike is shown.

Brain Diseases↗
PubMed2006

Electrocardiographical case. An elderly lady with chest pain. Diagnosis: isolated posterior myocardial infarct (MI).

A 72-year-old woman with diabetes mellitus, hypertension and dyslipidaemia presented with severe chest pain of four hours duration. Her electrocardiogram (ECG) showed tall R waves in leads V1-2, and ST segment depression in leads V1- 4, consistent with an isolated posterior myocardial infarction (MI). Emergency coronary angiogram showed an occluded left circumflex coronary artery, and primary angioplasty and stenting was performed. The ECG criteria for isolated posterior MI and pitfalls in using the conventional 12-lead ECG are discussed.

Aged↗
PubMed2005

Asynchronous burst-suppression in a child with callosal Ki-1 anaplastic large cell lymphoma.

A 13-year-old girl with Ki-1 anaplastic large cell lymphoma (Ki-1ALCL) bulky deposits in the brain developed raised intracranial pressure and coma associated with asynchronous burst-suppression following standard dose cranial irradiation. Supportive care, steroids, and chemotherapy resulted in clinical improvement. Burst-suppression coma may be reversible when secondary to tumor, decrease in steroids, or radiation effects; the asynchrony localizes the lesion to cortical interconnections such as the corpus callosum.

Adolescent↗
PubMed2005

Self-efficacy, coping, and difficulties interacting with health care professionals among women living with breast cancer in rural communities.

This study examined self-efficacy, coping, and social support in relation to difficulties interacting with physicians and nurses among women living with breast cancer. One hundred women living in rural, mountainous communities of northeastern California were recruited, with 89 providing complete data for this study. All women completed a battery of questionnaires that included the CARES--Medical Interaction Subscale and measures of self-efficacy, coping, satisfaction with social support, and demographic and medical characteristics. In a multiple regression analysis, difficulties interacting with medical professionals were found to be greater among women who were not married, who used more behavioral disengagement or less self-distraction to cope with breast cancer, and who reported less self-efficacy for affect regulation and for seeking and understanding medical information. Emotional venting and satisfaction with social support for dealing with cancer-related stress were not, however, significantly related to difficulties in interacting with the medical team. This model accounted for an adjusted value of 42% of the variance. Further research is needed to identify possible causal relationships related to these findings and to determine what interventions might be warranted to improve medical interactions for women with breast cancer living in rural areas.

Adaptation, Psychological↗
PubMed2005

Prenatal screening for congenital heart disease using real-time three-dimensional echocardiography and a novel 'sweep volume' acquisition technique.

OBJECTIVES: Conventional prenatal screening for congenital heart disease (CHD) involves a time-consuming and highly operator-dependent acquisition of the four-chamber view and outflow tracts. By acquiring the entire fetal heart instantaneously as a single volume, real-time three-dimensional echocardiography (RT3DE) may facilitate fetal cardiac screening. METHODS: Four reviewers, each experienced with fetal cardiac imaging, blindly and independently evaluated a single cardiac volume from each of 18 fetuses (11 normal, seven with CHD). Two-dimensional echocardiography served as the gold standard. Three-dimensional evaluation of each fetus included a series of volume acquisitions lasting 2-6 s each. A 'sweep volume' technique was developed to fit larger hearts into a single non-gated volume. RESULTS: RT3DE had a high sensitivity for detecting CHD (93%), with only a single case being missed by two observers. Specificity for CHD was low (45%), with a high rate of 'cannot determine' responses and false positive artifacts. CONCLUSIONS: These preliminary results suggest that RT3DE has the potential to function as a screening tool for fetal heart disease. However, artifacts must be recognized and minimized, resolution must improve, and substantial training will be necessary prior to widespread clinical use.

Artifacts↗
PubMed2005

Soccer injury in the lower extremities.

Information about soccer injuries is required to develop prevention and rehabilitation programmes. Most soccer injuries occur in the lower extremities. This type of injury is reviewed here. Definitions of injury, injury rate, injury percentage, mechanism of injury, anatomical region of injury, type of injury, and severity of injury are summarised. In each section, a description and summary of the data are provided. Finally, the limitations of the studies and suggestions to improve the investigation of soccer injuries are provided.

Ankle Injuries↗
PubMed2004

Altered expression of preproenkephalin and prodynorphin mRNA in a genetic model of paroxysmal dystonia.

The dtsz mutant hamster represents a model of primary paroxysmal dystonia, in which dystonic episodes occur in response to stress. Previous examinations demonstrated striatal dysfunctions in dtsz hamsters. In the present study, in situ hybridization was used to examine preproenkephalin and prodynorphin expression as potential indices of imbalances between the striatopallidal and striatonigral pathways. Brain analyses were performed in dtsz hamsters under basal conditions, i.e., in the absence of dystonia, as well as mutant hamsters that exhibited severe stress-induced dystonic attacks immediately prior to sacrifice. In the striatum the basal expression of prodynorphin tended to be higher, while that of preproenkephalin tended to be lower in mutant hamsters in comparison to non-dystonic control hamsters. Significant basal changes were restricted to higher levels of prodynorphin in the ventrolateral striatum and lower prodynorphin and preproenkephalin mRNA expression in the hippocampus and/or in subregions of the hypothalamus. After stressful stimulation, the neuropeptides increased in several regions in both animals groups. In comparison to stimulated control hamsters, a significantly lower prodynorphin expression was found in several limbic areas of stimulated mutant hamsters during the manifestation of dystonia, while preproenkephalin mRNA was significantly lower in the anterior and dorsal striatal subregions and in nucleus accumbens. Since changes in the expression of these opioid peptides have been suggested to be related to abnormal dopaminergic activity, the present findings may reflect disturbances in striatal dopaminergic systems, and also in limbic structures in the dtsz mutant, particularly during the expression of dystonia.

Analysis of Variance↗
PubMed2004

Randomized, controlled trial of the double setup tracheal tube during fibreoptic orotracheal intubation under general anaesthesia.

BACKGROUND: Impingement of the tracheal tube (ETT) on upper airway structures during railroading over the fibreoptic bronchoscope (FOB) occurs commonly. Potential complications of impingement include prolonged intubation time, leading to arterial desaturation, failed intubation and laryngeal trauma. The objective of this randomized, controlled trial was to assess the effect of the double setup ETT (a paediatric ETT is placed inside an adult ETT) on the incidence of impingement during orotracheal fibreoptic intubation. METHOD: Two hundred patients were randomized to have a single ETT or double setup ETT. After induction of anaesthesia, fibreoptic orotracheal intubation was performed. The degree of impingement of the ETT during advancement over the FOB was assessed using a standardized scoring system based on the manoeuvres required to overcome the impingement. RESULTS: The incidence of impingement was lower using the double setup ETT compared with the single ETT (18 vs 93%, P<0.001). The double setup ETT also reduced the incidence of impingement requiring more than a simple 90 degrees counterclockwise rotation to achieve intubation (3 vs 14%, P=0.01) and reduced the median intubation time (31 vs 35 s, P=0.046). CONCLUSIONS: The double setup ETT is effective in reducing ETT impingement and in reducing intubation time. We did not find an association between ETT impingement and arterial desaturation.

Adolescent↗
PubMed2004

A basis of the acanthocytosis in inherited and acquired disorders.

Acanthocytosis refers to the transformation of the normal biconcave disc erythrocyte into one with a few irregularly shaped external projections distributed unevenly at its membrane surface. It is associated with a variety of inherited and acquired disorders. A relationship between the acanthocytosis in chorea-acanthocytosis and an alteration of Band 3, the anion exchange protein, has been previously suggested. We have previously proposed a mechanism of erythrocyte shape control in which decrease and increase of the ratio of the outward-facing (Band 3(o)) and inward-facing (Band 3(i)) conformations of Band 3 contracts and relaxes the membrane skeleton, thus promoting echinocytosis and stomatocytosis, respectively. The equilibrium Band 3(o)/Band 3(i) ratio is determined by the Donnan equilibrium ratio of anions and protons, increasing with the increase of the Donnan ratio. Based on the evidence suggesting that the acanthocyte and echinocyte are interrelated, the mechanism could explain by a decrease of the Donnan ratio the occurrence of acanthocytes in pyruvate kinase and pyrimidine 5'-nucleotidase deficiencies, dehydrated hereditary stomatocytocytosis, In(Lu) phenotype, chorea-acanthocytosis, and McLeod phenotype. Consistent with the proposed mechanism indicating that the membrane skeleton is an important determinant of the erythrocyte shape, is the alteration of its conformation in chorea-acanthocytosis, McLeod phenotype and Fanconi's anemia. In agreement with the proposed mechanism indicating that Band 3 conformation controls the erythrocyte shape are the occurrence of an acanthocytosis in individuals expressing the rare Band 3 HT variant and of alterations of Band 3 properties in chorea-acanthocytosis and In(Lu) phenotype. The observations that the lipid composition or organization are normal in chorea-acanthocytosis and McLeod phenotype are supportive of the proposed mechanism since it postulates that the lipid bilayer has a secondary role in determining the erythrocyte shape. The acanthocytoses in alcoholic cirrhosis and abetalipoproteinemia are accompanied by significant increases of the cholesterol level and of the ratio of sphingomyelin and glycerophospholipids, respectively. However, they could occur by a change of the Band 3 conformation since cholesterol binds specifically to Band 3 and inhibits its anion transport activity, and that sphingomyelin potentiates this inhibition. Thus, the acanthocytosis could involve an alteration of the Band 3 conformation.

Acanthocytes↗
PubMed2004

A hypothesis on the role of the electrical charge of haemoglobin in regulating the erythrocyte shape.

A previously proposed mechanism of erythrocyte shape has been proposed in which the ratio of the two conformations of Band 3, the anion exchange protein, controls the erythrocyte shape by modifying the degree of contraction or relaxation of the membrane skeleton. This mechanism was previously shown to explain several observations related and unrelated to the erythrocyte shape. We show that it can also explain the occurrence of target cells in blood smears of individuals expressing Hb A variants with significantly lower and higher isoelectric points. This would provide further support of its validity and would have the following implications. The electrical charge of of Hb A influences the erythrocyte shape and deformability, thus explaining the low level of expression of Hb A2 with an isoelectric point significantly higher than Hb A. It would suggest that Hb A2 has a physiological function related to the control of the erythrocyte shape. This could be of regulating the activity of the K-Cl cotransport system or of tuning finely the cell pH. A role of haemoglobin in the control of the erythrocyte shape would ensure a more efficient oxygenation of tissues and removal of carbon dioxide generated by tissues. It would also provide a basis for the absence of spreading in populations of some haemoglobin variants differing only by the electrical charge.

Adaptation, Physiological↗
PubMed2004

Accuracy and reliability of a Cosmed K4b2 portable gas analysis system.

The purpose of this study was to assess the validity and reliability of a Cosmed K4b2 portable telemetric gas analysis system. Twelve physically fit males performed a treadmill running session consisting of an easy 10 min run, a hard 3 min run and a 1 min sprint (with rest periods of 10 min separating each run), on four separate occasions. Sessions were identical with the exception of the apparatus used to measure VO2. During two (test-retest) sessions a Cosmed K4b2 portable gas analysis system was used; in another, a laboratory metabolic cart and, in one session, both systems were used to measure VO2 simultaneously. Comparison of Cosmed K4b2 and metabolic cart measurements in isolation revealed significantly (p < 0.05) increased values of VO2, VCO2, FE CO2 (except FE CO2 at 10 min) and lower values of FE O2 for each run duration by the Cosmed system. Linear regression equations to predict metabolic cart results from Cosmed values were, respectively; cart VO2 = 0.926 (Cosmed VO2-0.227 (r2 = 0.84) and cart VCO2 = 1.057 (Cosmed VCO2-0.606 (r2 = 0.92). Bland-Altman plots and comparison of the test-retest cosmed measurements revealed that the K4b2 system showed good repeatability of measurement for measures of VE, VO2 and VCO2, particularly for 10 min and 3 min tests (ICC = 0.7-0.9, p < 0.05). In conclusion, the Cosmed K4b2 portable gas analysis system recorded consistently higher VO2 and VCO2 measurements in comparison to a metabolic cart. However, satisfactory test-retest reliability of the system was demonstrated.

Adult↗
PubMed2004

Stem cell cardiomyoplasty: state-of-the-art.

Congestive heart failure (CHF) remains the most common diagnosis made in cardiology wards today. No long-term therapeutic option for end-stage CHF is available except for orthotopic heart transplant. Cellular-based therapy has emerged as a potential new therapy for patients with advanced heart failure. Different cell types are being explored in preclinical and clinical studies with encouraging results. Critical issues, such as types of cells, ideal number of cells, route of delivery, timing and targets of delivery, remain to be optimised to maximise the benefits of the cell therapy. In this review, we seek to summarise the latest data and postulate future directions in this potentially exciting field.

Animals↗