Biomedical subjects
Publications and source records attributed to K L Chan.
We report a case of a subcutaneous arteriovenous fistula that developed after aortic surgery. A careful physical examination and the selective use of imaging tests can differentiate this relatively benign complication from the more serious causes of a continuous murmur in this setting.
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Explore the source record for details and available documents.
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A benzooxyquinazoline alkaloid, samoquasine A (1), has been isolated from the seeds of Annona squamosa, and its structure was elucidated by spectroscopic and chemical methods.
PURPOSE: Successful small bowel transplantation requires effective immunosuppression that preserves intestinal function but avoids opportunistic infection. This study aims to evaluate FK506 as a single immunosuppressant in different pretreatment regimens in a rat high responder strain combination. METHODS: Lewis --> DA rat heterotopic small bowel transplantation was performed. Studied groups were (1) untreated control, n = 12; (2) FK-1, n = 8; (3) FK-3, n = 8. FK506 (2 mg/kg/d, intramuscularly) was given to the recipients for 1 day (FK-1) and 3 days (FK-3) before small bowel transplantation, followed by 2 weeks of subtherapeutic treatment (0.3 mg/kg/d, intramuscularly) after small bowel transplantation. Syngeneic small bowel transplantation also was performed (n = 8). FK blood levels, maltose absorption test, histology, and bacteriology were performed at different postoperative days. RESULTS: Allograft survival was prolonged significantly with FK pretreatment, being more so in FK-3 group (FK-1, 22.2 +/- 1.5 d; FK-3, 40.7 +/- 14.1 d; control, 6.6 +/- 0.8 d; P< .01). In the first postoperative week, FK blood level was significantly higher in FK-3 group (19.8 +/- 1.5 ng/mL) than in FK-1 group (5.0 +/- 0.4 ng/mL; P < .05). There was no evidence of systemic infection in either FK-treated group. For maltose absorption, control allograft was abnormal on day 7 correlating to severely damaged intestinal architecture. In contrast, FK-treated allografts showed well-protected intestinal structure and normal absorption on days 7 and 21. CONCLUSION: High FK506 blood levels in the first postoperative week, achieved with FK pretreatment, prolonged intestinal allograft survival and preserved intestinal structure and function without allowing systemic infection.
PURPOSE: The mode of Helicobacter pylori spread is not well defined. Urea breath test (UBT) is an accurate and noninvasive method for H pylori detection. This study evaluates the role of intrafamilial spread of H pylori using UBT. METHODS: The family members of 16 Hpylori-positive and 16 negative (control) children confirmed by histology and rapid urease test were investigated with UBT. A 58% change was considered positive. RESULTS: A total of 139 persons (72 in the positive group; 67 in the control group) were studied. Fifty-eight (81%, 58 of 72) and 13 (19%, 13 of 67) were found to be positive in the H pylori-positive and control groups, respectively (P < .01). Among children from 19 positive mothers, the positive rate was 60% (25 of 42), whereas among children of negative mothers, the positive rate was 16% (4 of 25; P < .01). The positive rate among children of positive fathers was 66% (23 of 35), whereas that among children of negative fathers was 30% (7 of 23; P < .01). When both parents were H pylori-positive, the children's positive rate was 83% (19 of 23); when both parents were negative, the children's positive rate was 0% (0 of 9; P < .01). CONCLUSIONS: There is strong evidence of intrafamilial spread of H pylori. The positivity of parents with H pylori has an important bearing on their children's H pylori status.
Atrial fibrillation is a common arrhythmia, particularly in the older age groups. It confers an increased risk of thromboembolism to these patients, and multiple clinical risk factors have been identified to be useful in predicting the risks of thromboembolic events. Recent studies have evaluated the role of transesophageal echocardiography (TEE) in the evaluation of patients with atrial fibrillation. The purpose of this review is to evaluate the significance of transesophageal echocardiographic findings in the prediction of thromboembolic events, particularly stroke, in patients with nonvalvular atrial fibrillation, with an emphasis on recently reported prospective studies. Aortic plaque and left atrial appendage abnormalities are identified as independent predictors of thromboembolic events. Although they are associated with clinical events, they also have independent incremental prognostic values. Other transesophageal echocardiographic findings, such as patent foramen ovale and atrial septal aneurysm, have not been found to be predictors of thromboembolic events in this patient group. Thus, TEE is a useful tool in stratifying patients with nonvalvular atrial fibrillation into different risk groups in terms of thromboembolic events, and it will likely play an important role in future studies to assess new treatment strategies in high-risk patients with atrial fibrillation.
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Outrage of modesty (OOM) offenders cause considerable annoyance and distress to their victims. The offending behaviours include touching, grabbing or fondling of erogenous or non-erogenous parts of the victim's body. The purpose of this study is to examine a prison cohort of OOM offenders and to compare them with a group of OOM offenders who had been remanded in a state mental hospital. All prisoners serving sentence over a two-year study period were interviewed. They were of similar mean age to the hospital cohort but were better educated, more likely to be married and most were working. Victims tended to be young females with an average age of 19 years. Psychotic disorders were rarely present, although 15% had a dissocial personality disorder. Those with previous OOM convictions were likely to have had past psychiatric consultations and were more likely to be unmarried. However, there were no statistically significant differences between convicted first-time offenders and repeat offenders with respect to age, educational level, nature of offences and alcohol consumption. The prisoners were less inclined to commit their offences in the mornings. Breasts and genitalia were the favoured targets for molest action, irrespective of time or place or whether the offence was committed by a first or repeat offender. The offences were often committed along staircases, corridors and in crowded public places.
To gain better understanding into the causes of molesting behaviour in males, we examined a prison cohort of molesters and compared them with a control group comprising thieves. The molesters were older, had attained a higher educational level and were more likely to be married. They had their initial sexual intercourse at an older age but tended to have multiple sexual relationships and were less likely to report having viewed pornographic material. Three months prior to committing their offences, molesters seemed to engage in less sexual activity. The implications are that molesters had a need for more explicit sexual contact but were unable to sustain ongoing, stable, intimate sexual relationships.
A fuzzy color segmentation approach is developed for the analysis of colonoscopic images. The segmentation is made up of two phases: segmentation through histogram space filtering and region merging using fuzzy rule-base reasoning. The first phase involves using a scale-space filter to analyze the hue, saturation, and intensity (HSI) histograms to determine the number of classes and construct a 3-D class grid. The color image is then segmented based on the class grid. In the second phase, region merging based on applying the fuzzy rule-base is employed to guide the combining process of the segmented regions. For fuzzy reasoning, three criteria are evaluated, namely, the edge strength along the boundary, color similarity, and spatial connectivity of adjoining regions. Experimental testing of the proposed method applied on colonoscopic images was conducted, and the results are encouraging.
OBJECTIVE: The objective of this study was to evaluate the use of three-dimensional CT and virtual bronchoscopy in the treatment of neonates, infants, and children with esophageal atresia and tracheal stenosis. CONCLUSION: Long-gap (n = 1) and short-gap (n = 5) esophageal atresia, long-segment stenosis (n = 2), patent poststenting trachea (n = 1), normal trachea without fistula (n = 1), and tracheal bronchus (n = 1) were studied. Fistulas between the lower esophagus and carina were noted in all six cases of esophageal atresia. All CT findings correlated with operative or bronchoscopy findings. Sensitivity and specificity were 100%. Three-dimensional CT and virtual bronchoscopy are accurate and useful techniques in the preoperative assessment of esophageal atresia and tracheal stenosis in neonates, infants, and children.
BACKGROUND: In vitro studies have shown a discrepancy between aortic valve area (AVA) measurements derived invasively by Gorlin equation (Gorlin AVA) and noninvasively by Doppler echocardiography (Doppler-echo) continuity equation (Doppler AVA) during low flow states. OBJECTIVE: To assess whether a flow-related discrepancy between Gorlin AVA and Doppler AVA occurs in the clinical setting in patients with isolated valvular aortic stenosis. PATIENTS AND METHODS: Seventy-five consecutive patients with isolated valvular aortic stenosis, who had AVA determined both invasively by Gorlin equation and noninvasively by Doppler-echo continuity equation, were retrospectively reviewed. RESULTS: Gorlin AVA and Doppler AVA correlated (r=0.68) over the narrow AVA range (Gorlin AVA 0.30 to 1.22 cm2); however, Doppler AVA was systematically larger than Gorlin AVA (0.80+/-0.21 versus 0.70+/-0.23 cm2, AVA difference = 0.10+/-0.17 cm2, P<0.0001). The AVA difference was inversely related to invasive cardiac index (r=-0.51) and was significantly greater at low flow states (cardiac index less than 2.5 L/min/m2) than at normal flow states (cardiac index 2.5 L/min/m2 or more) (0.16+/-0.15 versus -0.03+/-0.15 cm2, P<0.0001). Independent predictors of the AVA difference were the difference between Doppler-echo and invasive cardiac output (P<0.0001); the difference between Doppler-echo and invasive mean transvalvular pressure gradient (P=0.0002); and the average cardiac output (Doppler-echo plus invasive cardiac output/2, P=0.001) at the time of the hemodynamic assessments. The AVA difference was not related to average pressure gradient, average AVA or patient characteristics. CONCLUSIONS: A flow-related discrepancy between Gorlin AVA and Doppler AVA occurs in the clinical setting of patients with isolated valvular aortic stenosis. This discrepancy should be considered when assessing aortic stenosis severity during low flow states, where Gorlin AVA may be significantly smaller than Doppler AVA.
Patients remanded over a two-year period to Woodbridge Hospital by Court Order were studied retrospectively. Schizophrenia was the most common diagnosis, theft and robbery the most prevalent offences. Males greatly outnumbered females. There were important gender differences, with males tending to commit sexual offences and females, theft and mischief. Males were less likely to be acquainted with their victims but those who caused hurt were more likely to know their victims. Outrage of modesty and theft were more likely to be committed against strangers. The reconviction rate was 26%, with repeat offenders more likely to commit sexual offences and theft. Patients who had previous psychiatric hospitalisation were more likely to be attending follow-up prior to and after release from remand and were more likely to have schizophrenia. Those assessed to be fit to plead were either fined or given jail sentences. Unsoundness of mind and unfitness to plead were associated with further remand in this hospital.