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Biomedical subjects

H Tan

Publications and source records attributed to H Tan.

At least 19 recordsLinked to original sources
PubMed2006

Cardiovascular risk factors and anthropometric measurements of adolescent body composition: a cross-sectional analysis of the Third National Health and Nutrition Examination Survey.

OBJECTIVE: To assess the association between certain cardiovascular risk factors that are commonly clustered among individuals with insulin resistance syndrome (IRS) and adolescents' body composition measurements. METHODS: We examined a total of 1068 adolescents aged 12-16 years from the Third National Health and Nutrition Examination Survey. The sex-specific third tertiles of glucose, triglycerides, systolic blood pressure and first tertile of high-density-lipoprotein (HDL) cholesterol were used to classify the presence of each IRS component. We compared adolescents with none, one, two and three/four IRS components across a series of body composition measurements and lipid profile. RESULTS: About 18% of the adolescents had three or four IRS components. Overall, IRS among adolescents is more likely to be associated with body weight and measurements related to body girths and less likely to be associated with the measurements related to body lengths. Multivariate analysis results showed that the odds of being at increased risk of obesity (body mass index z-score> 0.85) were significantly greater among those with two (odds ratio (OR)=4.5; 95% CI 2.5-8.2) and three/four (OR=8.9, 95% CI 4.5-17.5) IRS components compared to those without any IRS components. Across sex, the level of non-HDL cholesterol was significantly higher among adolescents with more IRS components (P for trends <0.05). CONCLUSIONS: The clustered cardiovascular risk factors are strongly associated with an increased risk of obesity and higher levels of non-HDL cholesterol among adolescents.

Adolescent↗
PubMed2005

Thrombolytic therapy with tissue plasminogen activator for superior vena cava thrombosis in an infant with sepsis.

Superior vena cava syndrome is rare in infants, and rarely responds to conservative treatment. We report a 22-mo-old girl with superior vena cava syndrome due to the use of a central venous line and/or sepsis. Doppler study and computed tomography angiography of the neck showed thrombosis within the superior vena cava and jugular veins. She was admitted to a monitored setting and received recombinant tissue plasminogen activator for 2 d. The clinical features of superior vena cava syndrome disappeared completely 3 d after treatment. No complications were observed and radiological investigations showed blood flow through the thrombus after treatment. Systemic recombinant tissue plasminogen activator may be useful in the treatment of superior vena cava syndrome in children.

Catheterization, Central Venous↗
PubMed2005

Debriefing after critical incidents for anaesthetic trainees.

This survey investigated the need, and the availability, of debriefing after critical incidents for training anaesthetists. A cross-sectional postal survey of all Australian anaesthetic trainees was conducted in May 2002. Four hundred and nineteen responses were analysed (response rate 64%). Debriefing after a critical incident was perceived by most trainees to be useful, however 36% (n = 149) had never been debriefed. Trainees ranked their preferred content for a debriefing as 'anaesthetic issues' followed by the 'psychological impact of the incident' 'patient issues' and 'surgical issues'. Almost half of respondents reported that they did not feel supported by their anaesthetic department after a negative outcome incident. Trainees who had debriefings were more likely to feel supported by senior colleagues. Debriefing after critical incidents should be an integral part of the supervision of anaesthetic trainees.

Adult↗
PubMed2005

A whistling face syndrome case with bilateral skin dimples.

The whistling face syndrome (Freeman-Sheldon Syndrome) is a rare disorder characterized by typical face and limb abnormalities. A wide range of clinical findings have been reported. We report unusual skin dimples in a sporadic case with the whistling face syndrome.

Arthrogryposis↗
PubMed2004

Clostridium difficile colitis in patients after kidney and pancreas-kidney transplantation.

Limited data exist about Clostridium difficile colitis (CDC) in solid organ transplant patients. Between 1/1/99 and 12/31/02, 600 kidney and 102 pancreas-kidney allograft recipients were transplanted. Thirty-nine (5.5%) of these patients had CDC on the basis of clinical and laboratory findings. Of these 39 patients, 35 have information available for review. CDC developed at a median of 30 days after transplantation, and the patients undergoing pancreas-kidney transplantation had a slightly higher incidence of CDC than recipients of kidney alone (7.8% vs. 4.5%, P>0.05). All but one patient presented with diarrhea. Twenty-four patients (64.9%) were diagnosed in the hospital, and CDC occurred during first hospitalization in 14 patients (40%). Treatment was with oral metronidazole (M) in 33 patients (94%) and M+oral vancomycin (M+V) in 2 patients. Eight patients had recurrent CDC, which occurred at a median of 30 days (range 15-314) after the first episode. Two patients (5.7%) developed fulminant CDC, presented with toxic megacolon, and underwent colectomy. One of them died; the other patient survived after colectomy. CDC should be considered as a diagnosis in transplant patients with history of diarrhea after antibiotic use, and should be treated aggressively before the infection becomes complicated.

Adult↗
PubMed2004

Isolation and characterization of endophytic Streptomyces strains from surface-sterilized tomato (Lycopersicon esculentum) roots.

AIMS: To isolate endophytic Streptomyces strains from tomato and examine their antimicrobial activity. METHODS: Endophytic Streptomyces strains were isolated using surface-sterilization methods and identified by morphological characteristics. Antimicrobial activities were measured by the agar plate sensitivity method. Antifungal activity in vivo was measured by seedling mortality in infested soils. RESULTS: Twenty-one per cent of endophytic streptomycete isolates produced antibacterial metabolites and 41% produced antifungal metabolites in S medium. Sixty-five per cent of the most frequently isolated strains inhibited the growth of Rhizoctonia solani by the antibiosis assay but only 32% produced metabolites active against R. solani in S medium. Growth promotion and enhanced disease resistance of seedlings inoculated with Streptomyces sp. strain S30 were observed in tomato but not in cucumber seedlings. CONCLUSIONS: Endophytic Streptomyces spp. strains were successfully isolated using stringent methods and strain S30 promoted growth and enhanced resistance to R. solani in tomato seedlings. SIGNIFICANCE AND IMPACT OF THE STUDY: Endophytic streptomycetes showing antifungal activity in vitro and in vivo may indicate the potential for their use as biocontrol agents particularly of R. solani disease of tomato seedlings.

Anti-Bacterial Agents↗
PubMed2003

Lipids and coronary heart disease in Asia.

In Western countries, it has been shown that coronary heart disease (CHD) is related to high serum total cholesterol (TC) levels. In less developed continents such as Asia and Africa, serum lipid levels are low and CHD incidence is much lower as compared with Western countries. With growing urbanization and industrialization in Asia, it has been shown that there is a concomitant rise in the level of serum TC and with it a rise in CHD. In all the Asian countries, serum TC levels are also higher in the urban compared with the rural population. Singapore, the only Asian country which is 100% urbanized since 1980, showed a rise of serum TC similar to that seen in the US and UK from the 1950s to the 1980s followed thereafter by a fall. This is reflected in the trend (rise followed by a fall) of CHD morbidity and mortality as well. In spite of a declining trend in serum TC level, CHD morbidity and mortality are still high in Singapore and comparable to the Western countries. The rest of the Asian countries show a different pattern from Singapore. In general, there is still a rising trend in serum TC level and in CHD mortality in most Asian countries. However, Japan is considered an exception in having a decreasing CHD mortality in spite of an increasing trend in serum TC. This may be attributed to a better control of other CHD risk factors such as hypertension and smoking. The rising trend in serum TC level remains a cause for concern, as this will emerge as a major problem for CHD morbidity and mortality in the future.

Asia, Southeastern↗
PubMed2003

sanC--a novel gene involved in nikkomycin biosynthesis in Streptomyces ansochromogenes.

AIMS: To investigate the genes involved in the nikkomycin biosynthesis and their molecular mechanism. METHODS AND RESULTS: A 0.9 kbp SmaI fragment was cloned and sequenced which contains a complete open reading frame designated sanC (GenBank accession no. AF228522). In search of database, the deduced product of sanC was not homologous with any known proteins. The disruption and complementation of sanC showed that sanC is essential for nikkomycin biosynthesis in Streptomyces ansochromogenes. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: sanC is a novel and essential gene involved in nikkomycin biosynthesis in S. ansochromogenes.

Amino Acid Sequence↗
PubMed2003

Cloning and characterization of sanO, a gene involved in nikkomycin biosynthesis in Streptomyces ansochromogenes.

AIMS: To clone and characterize sanO, a gene involved in the biosynthesis of nikkomycins in Streptomyces ansochromogenes. METHODS AND RESULTS: A 4.5-kb BamHI-KpnI fragment was cloned and sequenced. Sequence analysis revealed that this fragment contains three complete open reading frames. The largest one with 2034 bp was designated sanO, which encodes a protein consisting of 667 amino acids with high similarity to module of peptide synthetase. sanO disruption mutants produced no nikkomycin X, but formed nikkomycin Z at almost the same level of the wild-type strain. The production of nikkomycin X can be recovered by genetic complementation of sanO disruption mutants. Primer extension also revealed that transcription start point(tsp) of sanO was localized 87 bp upstream of the potential start codon (GTG). CONCLUSIONS: sanO was essential for the biosynthesis of nikkomycin X. SIGNIFICANCE AND IMPACT OF THE STUDY: Nikkomycins have received increased interest of study because of their prospective application in agriculture and medicine. Cloning and characterization of genes involved in the nikkomycin biosynthesis will help to elucidate the whole biosynthetic pathway of nikkomycins.

Aminoglycosides↗
PubMed2003

Acute disseminated encephalomyelitis in children: outcome and prognosis.

BACKGROUND: Acute disseminated encephalomyelitis (ADEM) is the most common demyelinating disorder of childhood. Its clinical features, prognosis and treatment vary in different reports. OBJECTIVES: To examine a series of children with ADEM for clinical findings, course, recurrences, and possible variables affecting outcome. METHODS: Multicentric data collected from 7 tertiary referral centers were registered and evaluated in a central database in 1990 - 2001 for clinical, laboratory, and MRI features. Course and prognosis were assessed in patients with at least 12 months' follow-up. RESULTS: Forty-six patients were evaluated. Median age at onset was 8 years, M/F ratio, 1.7/1. Most common symptoms and signs pertained to the motor system and consciousness. Of 39 children with 12 months' follow-up, 71 % recovered completely. Thirteen (33 %) children had relapses. Patients who had more than one relapse (n = 4) presented with new symptoms at each attack. Treatment with high-dose methylprednisolone was associated with complete recovery, and tapering over more than 3 weeks, with a lower rate of relapses. MRI lesions could persist even in asymptomatic patients; in particular, periventricular lesions tended to disappear later than others. CONCLUSIONS: Complete clinical recovery is common and serious complications are rare in childhood ADEM, but the rate of relapses is considerable. Clinical picture at first relapse may help to identify patients likely to experience multiple relapses. The timing and duration of steroid treatment affects outcome.

Adolescent↗
PubMed2002

Phase I clinical and pharmacologic study of chronic oral administration of the farnesyl protein transferase inhibitor R115777 in advanced cancer.

PURPOSE: To determine the maximum-tolerated dose, toxicities, and pharmacokinetics of R115777, a farnesyl transferase inhibitor, when administered continuously via the oral route. PATIENTS AND METHODS: Patients with advanced solid malignancies were treated with R115777 using an interpatient dose escalation scheme starting at 50 mg bid. Pharmacokinetics were assessed on days 1, 28, and 56. RESULTS: Twenty-eight patients were entered onto the study and the median duration of treatment was 55 days. The dose-limiting toxicities were myelosuppression and neurotoxicity. At a dose of 400 mg bid, grade 4 leukocytopenia and neutropenia were seen in two of four patients. Neurotoxicity grade 3 developed in one of five patients at 500 mg bid and in one of 13 at 300 mg bid after 8 weeks of treatment. Common nonhematologic toxicities were nausea, vomiting, and fatigue. The recommended dose for phase II/III testing in this scheme is 300 mg bid. The pharmacokinetic studies indicated dose proportionality. Little accumulation occurred and steady-state levels were reached within 2 to 3 days. Analyses of historic tumor material showed that five of 15 of patients had a K-ras mutation in codon 12. Three patients with pancreatic, colon, and cervix carcinomas had stable disease and one patient with a colon carcinoma had a minor response accompanied by a more than 50% decrease in carcinoembryonic antigen tumor marker. A fifth patient, with platinum-refractory non-small-cell lung cancer, showed a partial response that lasted for 5 months. CONCLUSION: Continuous dosing of R115777 is feasible with an acceptable toxicity profile at a dose of 300 mg bid.

Administration, Oral↗
PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗
PubMed2002

Treatment of murine breast cancer cells with antisense RNA to the type I insulin-like growth factor receptor decreases the level of plasminogen activator transcripts, inhibits cell growth in vitro, and reduces tumorigenesis in vivo.

AIMS: To establish that cells from the murine mammary carcinoma cell line, EMT6, express type I insulin-like growth factor receptor (IGF-IR), tissue-type plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA). To investigate the role of IGF-IR in growth, transformation, and tumorigenesis in addition to its relation to tPA and uPA in EMT6 cells. To assess the suitability of the EMT6/syngeneic mouse model for studying the role of IGF-IR in tumorigenesis. METHODS: The presence of transcripts for IGF-IR, tPA, and uPA was determined by northern blot analysis using poly (A(+)) RNA derived from EMT6 cells transfected with an antisense IGF-IR construct or a construct lacking the antisense IGF-IR insert. Flow cytometry was used to measure IGF-IR protein. Assays were performed to determine cell proliferation, transformation, and the tumorigenicity of antisense IGF-IR transfected EMT6 cells and control transfected EMT6 cells. RESULTS: There was strong expression of IGF-IR, tPA, and uPA in EMT6 cells. EMT6 cells from clones carrying antisense IGF-IR displayed a significant decrease in cell proliferation and lost the ability to form colonies in soft agar. A decrease in tumour size occurred when cells carrying the antisense IGF-IR were injected into syngeneic mice. Reduced expression of tPA and uPA was seen in EMT6 cells carrying the antisense IGF-IR construct. CONCLUSIONS: The IGF-IR plays a role in the progression, transformation, and tumorigenesis of EMT6 murine mammary carcinoma cells. The suppression of IGF-IR mRNA in EMT6 cells decreases tPA and uPA expression. EMT6 cells and the syngeneic mouse provide a suitable model for studying the role of IGF-IR in breast tumour progression.

Animals↗
PubMed2001

Detection of widespread fluids in the Tibetan crust by magnetotelluric studies.

Magnetotelluric exploration has shown that the middle and lower crust is anomalously conductive across most of the north-to-south width of the Tibetan plateau. The integrated conductivity (conductance) of the Tibetan crust ranges from 3000 to greater than 20,000 siemens. In contrast, stable continental regions typically exhibit conductances from 20 to 1000 siemens, averaging 100 siemens. Such pervasively high conductance suggests that partial melt and/or aqueous fluids are widespread within the Tibetan crust. In southern Tibet, the high-conductivity layer is at a depth of 15 to 20 kilometers and is probably due to partial melt and aqueous fluids in the crust. In northern Tibet, the conductive layer is at 30 to 40 kilometers and is due to partial melting. Zones of fluid may represent weaker areas that could accommodate deformation and lower crustal flow.

Journal Article↗
PubMed2001

Rubral tremor after thalamic infarction in childhood.

The occurrence of tremor after thalamic lesions is well known. Delayed rubral tremor secondary to bilateral thalamic infarction is a rare finding and has not been reported previously in childhood. We present two children with a combined resting-postural-kinetic tremor caused by bithalamic infarction. The first child was a male 14 months of age, and the second was a male 9 years of age. These children come from unrelated families. On hospital admission of the first patient, generalized seizures and routine electroencephalogram (EEG) findings with diffuse spike-wave discharges predominantly over the left frontal area were clinically observed, leading to the initial diagnosis of epilepsia partialis continua. However, clinical observation and video-EEG monitoring of the movements revealed nonepileptiform accompaniments, favoring the diagnosis of rubral tremor. In the second patient, EEG revealed no paroxysmal activity and was within normal limits for age. In both patients, cranial magnetic resonance imaging revealed ischemic lesions in thalami bilaterally but failed to reveal any mesencephalic lesion. These patients demonstrate that thalamic infarction can cause rubral tremor in childhood.

Ataxia↗
PubMed2001

Endoscopic dacryocystorhinostomy in children.

BACKGROUND: Persistent nasolacrimal duct obstruction (NLDO) often requires treatment by probing, intubation, or balloon dacryoplasty. Refractory cases have been managed by external dacryocystorhinostomy (DCR), which leaves a scar; however, this procedure is generally avoided in young children. Endoscopic DCR has been successfully performed in adults and described in children. We report the success of this procedure in a series of pediatric patients. METHODS: A retrospective review of all endoscopic lacrimal procedures performed in a 3-year period was undertaken. Seventeen children (22 ducts) with persistent NLDO after at least one failed probing, with or without silicone tube placement, underwent endoscopic DCR. Follow-up ranged from 6 to 36 months, and success was defined as resolution of tearing and discharge by follow-up clinical evaluation and by parental history. RESULTS: All but 2 patients (88%) with NLDO showed complete resolution of tearing and discharge. These 2 patients had recurrent symptoms after the Crawford tubes were removed and required revision endoscopic DCR. No complications from this procedure were noted. CONCLUSIONS: Endoscopic DCR is a safe and effective means of treating persistent NLDO in infants and young children when simple probing, intubation, or balloon procedures have failed. The team ophthalmology-otolaryngology endoscopic approach provides a highly successful alternative for patients with a persistent distal obstruction that might otherwise require an external procedure.

Adolescent↗
PubMed2001

Postoperative morbidity, mortality, costs, and long-term survival in severely obese patients undergoing orthotopic liver transplantation.

OBJECTIVE: Severely obese patients who undergo orthotopic liver transplantation are likely to have higher morbidity, mortality, costs, and a lower long-term survival. METHODS: This case-control study was done at a university hospital. One hundred twenty-one consecutive patients who underwent liver transplantation between 1994 and 1996 were studied. Severe obesity was defined as body mass index (BMI) more than 95th percentile (>32.3 for women and >31.1 for men), and moderate obesity was defined as BMI between 27.3 and 32.3 for women and 27.8 and 31.1 for men. The outcome measures were intraoperative complications, postoperative complications (wound infections, bile leak, vascular complications), length of hospital stay, costs of transplantation, and long-term survival RESULTS: The baseline characteristics, UNOS status, and cause of liver disease at the time of transplantation were similar in severely obese (n = 21, BMI = 37.4+/-4.8 kg/m2), obese (n = 36, BMI 28.7+/-0.9 kg/m2), and nonobese patients (n = 64, BMI 23.8+/-2.5 kg/m2). The intraoperative complications and transfusion requirements were similar in all three groups. The postoperative complications such as respiratory failure (p = 0.009) and systemic vascular complications (p = 0.04) were significantly higher in severely obese patients. The overall perioperative complication rate was 0.61 (39 of 64 patients) in nonobese patients, 0.77 (28 of 36 patients) in obese patients, and 1.43 (30 of 21 patients) in severely obese patients (p = 0.01). Infections were the leading cause of death in all groups accounting for 57-66% of deaths. The length of hospital stay was significantly higher in obese patients. The hospital costs of transplantation were higher ($30,000-$40,000) in severely obese patients than in nonobese patients. The long-term patient survival was similar between the groups (Kaplan-Meier analysis). CONCLUSIONS: Despite higher postoperative complications, severely obese patients have an acceptable long-term survival, which is comparable to nonobese patients. The cost of transplantation is higher among severely obese patients. There was no increased incidence of cardiovascular mortality among severely obese patients during the follow-up period.

Adult↗