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Biomedical subjects

A Yung

Publications and source records attributed to A Yung.

36 records · Page 2Linked to original sources
PubMed1999

Comparison of the long-term efficacy of implantable defibrillators and sotalol for documented spontaneous sustained ventricular tachyarrhythmias secondary to coronary artery disease.

BACKGROUND: The relative efficacy of antitachycardia pacing implantable cardioverter defibrillators (ATPICD) and sotalol in the treatment of ventricular tachyarrhythmias is controversial. AIM: To compare the mortality in patients treated with ATPICD and sotalol for documented spontaneous sustained ventricular tachyarrhythmias occurring late after previous myocardial infarction. METHODS: In this non-randomised retrospective study of 139 consecutive patients all patients had inducible ventricular tachycardia at baseline electrophysiological studies. Before the availability of ATPICD, 22 patients were treated with sotalol as part of a randomised study comparing the efficacy of sotalol to amiodarone. After ATPICD became available sotalol was used in 49 patients in whom intravenous testing predicted sotalol to be effective and ATPICD were implanted in 68 patients in whom sotalol was predicted to be ineffective at electrophysiological testing. Thus, 68 patients were treated with an ATPICD and 71 with sotalol. RESULTS: The two groups were well-matched for age, type of presenting arrhythmia, severity of coronary artery disease and ventricular function. At 36 months Kaplan-Meier estimates of mortality from ventricular tachyarrhythmia were 0% with ATPICD and 15% with sotalol (p=0.03). Kaplan-Meier estimates of total mortality at 36 months were 12% with ATPICD and 25% with sotalol (p=0.09). Multivariate analysis showed hazard ratio of 7.9 (p=0.06) for death from ventricular tachyarrhythmia in patients treated with sotalol compared to ATPICD. CONCLUSIONS: While no difference in total mortality was demonstrated, treatment with ATPICD is probably superior to sotalol for preventing deaths due to ventricular tachyarrhythmia.

Aged↗
PubMed1997

Volumetric analysis of tumor extent in nasopharyngeal carcinoma and correlation with treatment outcome.

PURPOSE: To investigate the variability of tumor volume in nasopharyngeal carcinoma using quantitative measurements of tumor bulk derived from computed tomography, and to study the prognostic value of tumor volume in comparison with other variables. METHODS AND MATERIALS: Two hundred ninety patients with newly diagnosed nasopharyngeal carcinoma were included in the study. The primary tumor volume (PTV) and nodal tumor volume (NTV) were obtained by outlining the tumor contour followed by summation of areas in sequential pretreatment computed tomography axial scans. Total tumor volume (TTV) was obtained by adding the PTV and NTV. All patients had radiotherapy as the primary treatment, 67 patients also received cisplatin-based neoadjuvant chemotheraphy. RESULTS: A large variation in tumor volume was observed, especially in advanced stage disease. The median PTV (cc) in Ho's T1, T2, and T3 disease were: 6.9 (range: 0.9-42.7), 18.8 (1.6-127.9), and 52.4 (3.3-166.8). The median TTV (cc) in Ho's stage I to IV disease were: 7.6 (range: 1.3-42.7), 19.8 (3.2-55.7), 40.7 (4.1-222.7), and 51.1 (3.1-274.7). Patients with a large PTV (>60 cc) were associated with significantly poorer local control (5-year local control rate: 56%) and disease-specific survival (5-year survival rate: 53%). In patients with a small PTV (< or =20 cc), there were no significant differences in local control among different T stages. Large NTV (>30 cc) was associated with significantly higher distant failure rate (5-year distant relapse-free survival rate: 54%) and lower disease-specific survival (5-year survival rate: 40%). In multivariate analysis, only PTV was found to be an independent factor in predicting local control. CONCLUSION: A large variation of tumor volume was present in different T stage disease of nasopharyngeal carcinoma, and PTV represents an independent prognostic factor of local control that appears to be more predictive than Ho's T stage classification.

Adult↗
PubMed1997

Tumor control probability of nasopharyngeal carcinoma: a comparison of different mathematical models.

PURPOSE: Radiation dose and tumor volume are factors known to affect the local control of a given type of tumor. Local tumor control is a major factor to consider when a treatment plan is evaluated. This article reports the correlation between tumor control probability, dose, and volume in a retrospective study of 142 patients with nasopharyngeal carcinoma (NPC). METHODS AND MATERIALS: The tumor volume was outlined and calculated from a computed tomographic scan. Patients were categorized according to tumor volume and radiation dose received in treatment. Local control rate was calculated for each category by the Kaplan-Meier method. Mathematical models were fitted to correlate the local control rate, dose, and volume. Both empirical and mechanistic approaches were attempted; the former included logistic models with two and three parameters, and the latter, the formulation from Brenner and Bentzen with a radiobiological basis. RESULTS: Brenner's model estimated alpha at 0.041 Gy(-1) with 95% confidence limits (-0.032, 0.113) Gy(-1). The volume dependent constant h was estimated at 0.160 cm(-3) with 95% confidence limits (-0.729, 1.048) cm(-3). The Pearson correlation coefficient was 0.64. The magnitude and sign of the fitted parameters were reasonable and consistent with reported clinical experience. The other models were fitted with slightly better goodness of fit (r = 0.65 - 0.68), but with less interpretable parameters. CONCLUSION: Brenner's model is considered appropriate for a description of the dose and volume effect on the local control of the NPC. It could be used in combination with normal tissue complication probability for treatment plan evaluation to optimize treatment results.

Adult↗
PubMed1997

Usefulness of Semen Microscopy in the Diagnosis of a Difficult Case of Schistosoma haematobium Infection in a Returned Traveler.

Schistosoma haematobium is endemic in many countries of Southeast Asia, eastern and western Africa, and South America. It affects mainly the urinary system, although infection of the genital organs is not infrequent.1,2 Infection of male genital organs, especially of the seminal vesicles and prostate1,3 may result in hematospermia and infertility.2,4,5,6,7,8,9 The diagnosis of Schistosoma haematobium traditionally relies on demonstrating the presence of characteristic ova in urine and, less often, in feces. Serology is nonspecific and lacks sensitivity because the antigens utilized in the indirect hemagglutination assay are derived from Schistosoma mansoni. In addition, serology cannot differentiate past from recently acquired infection. We report a case of Schistosoma haematobium infection in a returned traveler in whom numerous ova were detected in semen despite repeated negative urinary and fecal examinations and negative serology.

Journal Article↗
PubMed1997

Missed opportunities for prevention of tuberculosis in Victoria, Australia.

SETTING: Victoria, Australia. OBJECTIVE: To ascertain missed opportunities for prevention in all persons notified in 1991 to the state registry with active tuberculosis (TB), and to examine aspects of case management relevant to prevention. DESIGN: A descriptive study. Records were reviewed for 231/236 cases of TB notified in the state of Victoria in 1991. Documentation of past screening for TB, preventive therapy, treatment of active disease and follow up was sought for all cases. Past screening was defined as past contact screening, migrant screening, refugee screening and health undertakings for TB. RESULTS: Of the 231 cases, 13 were not confirmed to have TB. Of the remaining 218 cases, 78% were foreign born, and of these, nearly half were diagnosed within 3 years of arriving in Australia. Nearly half of all cases (97/218) had some form of past screening for TB. The most common type of screening was refugee and migrant screening (45/218, 21%) followed by tuberculosis health undertakings (25/218, 12%) and contact screening (15/218, 7%). Of those with past screening, 70% (68/97) had a positive screening result at the time. Among these, the first screening episode resulted in the diagnosis of active TB in 5/68, and TB infection in 63/68. In the latter group only 5% (3/63) received preventive therapy. CONCLUSION: There are significant missed opportunities for prevention in Victoria, particularly in the foreign born cases who receive screening on entry into the country. For screening to be a meaningful exercise, preventive therapy should be used where medically indicated.

Adolescent↗
PubMed1995

Emergence of multidrug resistance in Campylobacter jejuni isolates from three patients infected with human immunodeficiency virus.

Single-drug resistance to tetracycline, doxycycline, erythromycin, or fluoroquinolones in Campylobacter isolates recovered from humans has been documented worldwide. Multidrug resistance to these antibiotics is rare in Campylobacter jejuni. We report the sequential development of multidrug resistance in C. jejuni isolates from three patients who were infected with human immunodeficiency virus. Multiple isolates recovered from stool specimens from these patients were ribotyped, and antibiotic susceptibility profiles were determined. The results indicated that each patient was infected with a single strain of C. jejuni that had progressively acquired resistance to the antibiotics used during treatment. The emergence of resistant isolates appeared to correlate with clinical relapse. In these patients, campylobacter enteritis was prolonged, severe, and relapsing, and antimicrobial therapy was required. Once these first-line antibiotics become ineffective, few other antibiotics are available for treating patients with campylobacter enteritis. Acquisition of antibiotic resistance in C. jejuni is therefore of concern in these cases.

AIDS-Related Opportunistic Infections↗
PubMed1995

In-111 DTPA Ommayagrams in leptomeningeal carcinomatosis.

Radionuclide Ommayagrams in 25 patients with leptomeningeal carcinomatosis were performed after injection of 0.5 mCl of In-111 DTPA into Ommaya shunt reservoirs to evaluate cerebrospinal fluid-shunt communication, detect the blockage of the cerebrospinal fluid pathway, evaluate the cerebrospinal fluid flow pattern, and predict the distribution of the chemotherapeutics. All results were correlated with MRI evaluations of the brain and spine, as well as clinical findings. Radionuclide Ommayagrams were found to be 73% sensitive and 100% specific in the evaluation of cerebrospinal fluid space disease. MRI of the spine and head was found to be 100% sensitive, but 86% specific for obstructive cerebrospinal fluid space disease.

Adolescent↗
PubMed1995

Status epilepticus in 37 Chinese children: aetiology and outcome.

OBJECTIVE: The aetiology and clinical features of status epilepticus (SE) are described, with the aim of defining any relationship between risk factors and clinical outcome. METHODOLOGY: A retrospective review was performed of 37 Chinese children admitted to Queen Mary Hospital, Hong Kong, from 1989 to 1993 with the diagnosis of SE. RESULTS: Eighty-six per cent had onset before 5 years of age; 60% were due to an acute central nervous system (CNS) insult, 11% were idiopathic, 13% had a pre-existing CNS insult, 5% were febrile and 11% were due to progressive encephalopathy. An abnormal neurological status was present in 24% before the episode of SE, and a history of seizures before the onset of SE was present in 35% of patients. Fifty-four per cent of the episodes of SE were generalized. The mortality rate was 11% during the period of follow up but no deaths were attributed to SE. Neurological sequelae were observed in 27% of patients and recurrent SE occurred in 12%. CONCLUSIONS: In those patients with normal neurological status before an episode of SE and without acute CNS insult or progressive encephalopathy, the outcome was favourable.

Age of Onset↗
PubMed1993

Tuberculous meningitis: a 30-year review.

Tuberculous meningitis remains an important illness that can be difficult to diagnose in a timely fashion and carries significant morbidity. We present a retrospective review of the cases of tuberculous meningitis diagnosed and treated at a single institution. Fifty-eight cases were identified and stratified according to stage of disease at presentation. Four patients (7%) died; three (5%) developed severe neurological sequelae. Poor outcomes were largely confined to cases presenting in an advanced stage and at the extremes of age. Corticosteroids were administered to 56 patients and may have contributed to the comparatively good outcome in these cases.

Adrenal Cortex Hormones↗
PubMed1992

Tolerance to the anticonvulsant effects of phenobarbital, trimethadione, and clonazepam in kindled rats: cross tolerance to carbamazepine.

The kindled-convulsion model was used to assess the development of tolerance and cross tolerance to the anticonvulsant effects of antiepileptic drugs. In Experiment 1, tolerance developed to the anticonvulsant effects of bidaily (one every 48 h) IP injections of phenobarbital, trimethadione, and clonazepam on convulsions elicited 1 h after each injection in kindled rats by amygdala stimulation. In Experiment 2, kindled rats that were tolerant to the anticonvulsant effects of phenobarbital, trimethadione, or clonazepam received bidaily IP injections of carbamazepine, each followed 1 h later by a convulsive amygdala stimulation. There was a statistically significant transfer of tolerance from phenobarbital to carbamazepine, but not from either trimethadione or clonazepam to carbamazepine. Apparently, tolerance to anticonvulsant drugs is most likely to transfer between drugs that are effective against similar kinds of clinical and experimental seizures and have similar putative mechanisms of action.

Amygdala↗
PubMed1988

Enhancement of growth of primary metastatic fresh human tumors of the nervous system by epidermal growth factor in serum-free short term culture.

Using the adhesive tumor cell culture system, we studied the effect of epidermal growth factor (EGF) on 16 primary and 7 metastatic fresh human tumors of the nervous system cultured in serum-free and serum-supplemented media at low cell density. In serum-free conditions, EGF significantly enhanced the growth of glial tumor cells. This positive effect was less pronounced for metastases to the brain. No significant enhancement was observed for the other tumor types (primitive neuroectodermal tumors and various tumors of neuroepithelial/mesenchymal origin). The addition of serum obscured this effect of EGF, even at the lowest cell densities. In 7 tumors, the simultaneous addition of platelet-derived growth factor did not enhance the EGF response. Subtypes of brain tumors respond to EGF in vitro under serum-free conditions.

Brain Neoplasms↗
PubMedDate not supplied

Outcome measure for paediatric rehabilitation: use of the Functional Independence Measure for children (WeeFIM). A pilot study in Chinese children with neurodevelopmental disabilities.

PURPOSE: To study the use of Functional Independence Measure for children (WeeFIM) in monitoring neurorehabilitation programmes for children with neurodevelopmental disabilities. METHODS: The neurorehabilitation team of the Children's Habilitation Institute of the Duchess of Kent Children's Hospital were trained to administer the WeeFIM. The WeeFIM was administered to children with various neuro-developmental impairment groups undergoing neurorehabilitation programmes in the hospital inpatient and also outpatient setting. The WeeFIM was scored on hospital admission and prior to discharge for those admitted for the rehabilitation programme. The WeeFIM profile was then monitored half yearly. The pilot study used WeeFIM in assessing 104 children with different medical disease categories. The disease or impairment categories included very low birth weight babies (n = 44), cerebral palsy (n = 19), Down's syndrome (n = 9), pervasive developmental disorder (n = 11), Duchenne Muscular Dystrophy (n = 18), and others (n = 3). RESULTS: WeeFim could be used to measure disability, monitor progress, enhance communication, measure the effectiveness of treatment, and document the benefits of rehabilitation intervention. It also served as a networking of neurorehabilitation programmes for different impairment categories in a continuum of settings: hospital, community, school and at home. WeeFIM was found to be a quick and reliable functional assessment instrument in this rehabilitation facility. CONCLUSIONS: WeeFIM could be used to assist neurorehabilitation clinicians in the selection of short term realistic goals and long term rehabilitation strategies for children with various neurodevelopmental disabilities, and the subsequent progress of the children could be monitored objectively.

China↗
PubMedDate not supplied

Imported malaria treated in Melbourne, Australia: epidemiology and clinical features in 246 patients.

BACKGROUND: Imported malaria is increasing in nonendemic countries, including Australia. The objective of this study was to describe the epidemiology and clinical features of travelers with imported malaria presenting to a specialist infectious diseases hospital. METHODS: A retrospective case series of 246 consecutively admitted inpatients with laboratory confirmed malaria. The main outcome measures were the proportion of patients infected with each malaria species, and relationship between species and country of birth, area of acquisition, adequacy of chemoprophylaxis, clinical features, laboratory investigations, and treatment. RESULTS: Plasmodium vivax caused 182 (68.9%) episodes, Plasmodium falciparum caused 71 (26.9%), Plasmodium ovale caused 5 (1.9%), and Plasmodium malariae 1 (0.4%). Fifty-six percent of patients reported chemoprophylaxis use. People born in a country with endemic malaria (36.6%) were less likely to have used chemoprophylaxis. Malaria was most commonly acquired in Papua New Guinea and Southeast Asia. The median times to diagnosis after return to Australia for P. falciparum and P. vivax infections were 1 and 9 weeks respectively. The longest interval between last arrival in Australia and presentation with P. falciparum malaria was 32 weeks. Fever (96%), headache (74%), and a tender or palpable spleen (40%), were the most common clinical features. Diarrhea was more common in P. falciparum, and rigors in P. vivax infections. Thrombocytopenia (71%), abnormal liver function tests and an elevated C-reactive protein (85%) were common. Six patients had severe falciparum malaria but no deaths occurred during the study period. CONCLUSION: Malaria remains a health threat for those traveling in endemic areas and is associated with failure to use chemoprophylaxis appropriately. Nonspecific clinical features may lead to delayed diagnosis and misdiagnosis. Malaria should be suspected in the febrile traveler, regardless of birthplace, prophylaxis, symptomatology, or the time that has elapsed since leaving the malarious area.

Adult↗