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Biomedical subjects

F Tan

Publications and source records attributed to F Tan.

At least 19 recordsLinked to original sources
PubMed2006

Recurrent episodes of arthritis in a hyperthyroid patient.

Antineutrophil cytoplasmic antibody (ANCA)- associated vasculitis is a potentially life-threatening adverse effect of antithyroid medications. We present a 22-year-old woman with Graves' disease who developed recurrent episodes of arthritis while on treatment with propylthiouracil. A diagnosis of propylthiouracil-induced ANCA-associated vasculitis was established only after exhaustive rheumatological investigations failed to establish a cause for her arthritis. Anti-myeloperoxidase antibody (anti-MPO) titres were grossly elevated at 172.7 RU/mL (0-20). Her arthritis resolved promptly following the withdrawal of propylthiouracil and the anti-MPO titres declined over 16 months to 66.8 RU/mL. While she did not develop the life-threatening renal or respiratory tract complications, there was a delay in establishing the correct diagnosis with its attendant morbidity. This case highlights the need for greater awareness of this relatively rare adverse effect of antithyroid medications so as to allow its early detection, leading to the prompt cessation of the offending medication.

Adult↗
PubMed2002

Chelation therapy for atherosclerotic cardiovascular disease.

BACKGROUND: Chelation therapy is being promoted and practiced all over the world as a form of alternative medicine in the treatment of atherosclerotic cardiovascular disease. It has been recommended as a safe, relatively inexpensive and non-surgical method of restoring blood flow in atherosclerotic vessels. At present the benefit of chelation therapy remains controversial at best. OBJECTIVES: The objective of this review is to assess the effects of ethylene diamine tetraacetic acid (EDTA) chelation therapy on clinical outcomes among patients with atherosclerotic cardiovascular disease. SEARCH STRATEGY: The reviewers searched the Cochrane Peripheral Vascular Diseases Group Trials Register, (last searched July 2002), the Cochrane Controlled Trials Register, (Cochrane Library Issue 2, 2002), MEDLINE and EMBASE for published articles and other relevant articles. Studies were also requested through correspondence with known Filipino practitioners of the procedure. SELECTION CRITERIA: Studies were included if they were randomized controlled trials of EDTA chelation therapy versus placebo or no treatment in patients with atherosclerotic cardiovascular disease. Main outcome measures considered included either total or cause-specific mortality, non-fatal cardiovascular events, direct or indirect measurement of disease severity, subjective measures of improvement or adverse events. DATA COLLECTION AND ANALYSIS: Two reviewers (MVV, FT) extracted data and assessed trial quality independently. Unresolved issues were considered by a third reviewer (ALD). Discrepancies were discussed until a consensus was reached. Authors were contacted for additional information. MAIN RESULTS: A total of five studies was included in the review. Mortality, non-fatal events, and cerebrovascular events were not reported in any of the studies. Four of the studies, with a total recruitment rate of 250 participants, showed no significant difference in the following outcomes: direct or indirect measurement of disease severity and subjective measures of improvement. One of the studies, which included only 10 patients, was interrupted prematurely, because of an apparent treatment effect. However, relevant data were not available in the report and have been requested from the authors. REVIEWER'S CONCLUSIONS: At present, there is insufficient evidence to decide on the effectiveness or ineffectiveness of chelation therapy in improving clinical outcomes of patients with atherosclerotic cardiovascular disease. This decision must be preceded by conducting randomized controlled trials that would include endpoints that show the effects of chelation therapy on longevity and quality of life among patients with atherosclerotic cardiovascular disease.

Arteriosclerosis↗
PubMed2002

Efficacy of orally delivered cochleates containing amphotericin B in a murine model of aspergillosis.

Cochleates containing amphotericin B (CAMB) were administered orally at doses ranging from 0 to 40 mg/kg of body weight/day for 14 days in a murine model of systemic aspergillosis. The administration of oral doses of CAMB (20 and 40 mg/kg/day) resulted in a survival rate of 70% and a reduction in colony counts of more than 2 logs in lungs, livers, and kidneys. Orally administered CAMB shows promise for the treatment of aspergillosis.

Amphotericin B↗
PubMed2001

Chiari Type I malformation presenting as glossopharyngeal neuralgia: case report.

OBJECTIVE AND IMPORTANCE: Chiari Type I malformation is an important pathological state in which the brainstem is compressed by the cerebellar tonsil. We present a case of glossopharyngeal neuralgia caused by Chiari Type I malformation. CLINICAL PRESENTATION: A 50-year-old male patient was admitted with glossopharyngeal neuralgia. Magnetic resonance imaging studies revealed caudal displacement of the left cerebellar tonsil. INTERVENTION: Small occipital craniectomy and C1 laminectomy were performed. The left cerebellar tonsil was resected. CONCLUSION: This glossopharyngeal neuralgia was caused by compression of the lower cranial nerves and brainstem by the displaced left cerebellar tonsil. Decompression and pain relief were obtained with resection of the cerebellar tonsil. The patient was pain-free 30 weeks after the operation.

Arnold-Chiari Malformation↗
PubMed2001

A short sequence within domain C of duck carboxypeptidase D is critical for duck hepatitis B virus binding and determines host specificity.

Virus-cell surface receptor interactions are of major interest. Hepadnaviruses are a family of partially double-stranded DNA viruses with liver tropism and a narrow host range of susceptibility to infection. At least in the case of duck hepatitis B virus (DHBV), host specificity seems controlled partly at the receptor level. The middle portion in the pre-S region of the viral large envelope protein binds specifically to duck carboxypeptidase D (DCPD) but not to its human or chicken homologue. Although domain C of DCPD is implicated in ligand binding, the exact pre-S contact site remains to be determined. We prepared and tested a panel of chimeric constructs consisting of DCPD and human carboxypeptidase D (HCPD). Our results indicate that a short region at the N terminus of domain C (residues 920 to 949) is critical to DHBV binding and is a major determinant for the host specificity of DHBV infection. Replacing this region of the DCPD molecule with its human homologue abolished the DHBV interaction, whereas introducing this DCPD sequence into HCPD conferred efficient DHBV binding. Extensive analysis of site-directed mutants revealed that both conserved and nonconserved residues were important for the pre-S interaction. There were primary sequence variations and secondary structural differences that contributed to the inability of HCPD to bind the DHBV pre-S domain.

Amino Acid Sequence↗
PubMed2000

Replacement of the transmembrane anchor in angiotensin I-converting enzyme (ACE) with a glycosylphosphatidylinositol tail affects activation of the B2 bradykinin receptor by ACE inhibitors.

To investigate further the relationship of angiotensin I-converting enzyme (ACE) inhibitors to activation of the B(2) bradykinin (BK) receptor, we transfected Chinese hamster ovary cells to stably express the human receptor and either wild-type ACE (WT-ACE), an ACE construct with most of the cytosolic portion deleted (Cyt-del-ACE), or ACE with a glycosylphosphatidylinositol (GPI) anchor replacing the transmembrane and cytosolic domains (GPI-ACE). BK or its ACE-resistant analogue were the agonists. All activities (arachidonic acid release and calcium mobilization) were blocked by the B(2) antagonist HOE 140. B(2) was desensitized by repeated administration of BK but resensitized to agonist by ACE inhibitors in the cells expressing both B(2) and either WT-ACE or Cyt-del-ACE. In GPI-ACE expressing cells, the B(2) receptor was still activated by the agonists, but ACE inhibitors did not resensitize. Pretreatment with filipin returned the sensitivity to inhibitors. In immunocytochemistry, GPI-ACE showed patchy, uneven distribution on the plasma membrane that was restored by filipin. Thus, ACE inhibitors were inactive as long as GPI-ACE was sequestered in cholesterol-rich membrane domains. WT-ACE and B(2) receptor in Chinese hamster ovary cells co-immunoprecipitated with antibody to receptor, suggesting an interaction on the cell membrane. ACE inhibitors augment BK effects on receptors indirectly only when enzyme and receptor molecules are sterically close, possibly forming a heterodimer.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Nitric-oxide-dependent pial arteriolar dilation in the female rat: effects of chronic estrogen depletion and repletion.

In this study, we compared endothelial nitric oxide synthase (eNOS)-mediated cerebral vasodilating responses in intact female rats, chronically ovariectomized (OVX) rats, and OVX rats treated for 2 weeks with 17beta-estradiol (E(2)). Under anesthesia, using intravital microscopy and a closed cranial window system, pial arteriolar diameter changes were monitored during sequential cortical suffusions of an eNOS-dependent dilator [acetylcholine (ACh)] and a direct NO donor [S-nitrosoacetylpenicillamine (SNAP)]. In separate rats from the same groups, we compared eNOS and caveolin-1 (CAV-1) protein abundance in pial arterioles (via immunofluorescence analyses). In untreated and low-dose E(2)-treated (1.0 microg x kg(-1) x day(-1)) OVX rats, ACh-induced vasodilations were virtually absent. High-dose E(2) treatment (100 microg x kg(-1) x day(-1)) restored ACh-induced pial arteriolar dilations to levels seen in intact females. The vasodilations elicited by SNAP and ADO were unaffected by chronic estrogen changes, indicating no direct estrogen influence on vascular smooth muscle (VSM) reactivity. Pial arteriolar eNOS protein abundance was diminished by ovariectomy and restored by high-dose E(2) treatment. Pial arteriolar CAV-1 expression was higher in OVX versus intact and E(2)-treated OVX females. These results suggest that long-term changes in estrogen directly influence brain eNOS functional activity. The estrogen-related changes in eNOS-dependent vasodilating function appear to be related, in part, to a capacity for E(2) to increase eNOS protein expression and, in part, to an E(2)-associated diminution in endothelial CAV-1 expression.

Acetylcholine↗
PubMed2000

Superoxide dismutase activity and zinc and copper concentrations in Parkinson's disease.

Although several hypotheses are currently being investigated the cause of Parkinson's disease (PD) is still unknown. The aim of this study was to determine red cell copper/zinc-superoxide dismutase (Cu/Zn-SOD) activity and copper and zinc concentrations both in plasma and in red cell in PD. In this preliminary assay, 30 patients with PD the mean age of 64 were studied. Additionally, a second group of older individuals without PD mean age of 61, were recruited to the study. The patient group was compared with the other group according to their red cell Cu/Zn-SOD activities, and plasma and red cell copper, zinc concentrations. Red cell Cu/Zn-SOD activity was measured spectrophotometrically while plasma and red cell copper, zinc concentrations were determined by atomic absorption spectrophotometer. The results were analysed by 'Student t-test' statistically. The results showed that red cell Cu/Zn-SOD activities and red cell copper and zinc and also plasma copper concentrations of the PD patients increased compared to older individuals without PD. These findings suggested that possibility of oxidative stress in PD was reflected on the blood including the red cell and plasma parameters.

Journal Article↗
PubMed2000

Human bradykinin B(2) receptor is activated by kallikrein and other serine proteases.

Bradykinin (BK) and kallidin (Lys-BK), liberated from kininogens by kallikreins, are ligands of the BK B(2) receptor. We investigated whether kallikreins, besides releasing peptide agonist, could also activate the receptor directly. We studied the effect of porcine and human recombinant tissue kallikrein and plasma kallikrein on [Ca(2+)](i) mobilization and [(3)H]arachidonic acid release from cultured cells stably transfected to express human BK B(2) receptor (CHO/B(2), MDCK/B(2), HEK/B(2)), and endothelial cells were used as control cells. As with BK, the actions of kallikrein were blocked by the B(2) antagonist, HOE 140. Kallikrein was inactive on cells lacking B(2) receptor. Kallikrein and BK desensitized the receptor homologously but there was no cross-desensitization. Furthermore, 50 nM human cathepsin G and 50 nM trypsin also activated the receptor; this also was blocked by HOE 140. Experiments excluded a putative kinin release by proteases. [(3)H]AA release by BK was reduced by 40% by added kininase I (carboxypeptidase M); however, receptor activation by tissue kallikrein, trypsin, or cathepsin G was not affected. Prokallikrein and inhibited kallikrein were inactive, suggesting cleavage of a peptide bond in the receptor. Kallikreins were active on mutated B(2) receptor missing the 19 N-terminal amino acids, suggesting a type of activation different from that of thrombin receptor. Paradoxically, tissue kallikreins decreased the [(3)H]BK binding to the receptor with a low K(D) (3 nM) and inhibited it 78%. Thus, kallikreins and some other proteases activate human BK B(2) receptor directly, independent of BK release. The BK B(2) receptor may belong to a new group of serine protease-activated receptors.

Animals↗
PubMed2000

Effects of the N-terminal sequence of ACE on the properties of its C-domain.

Angiotensin I-converting enzyme (ACE, kininase II) has 2 active domains (N and C) in a single peptide chain. Because we found its N-domain more stable than its C-domain, we investigated the effect of the amino-terminus of human ACE on the C-domain with a molecular construct expressed in Chinese hamster ovary cells (CHO) cells and transiently in HEK293 cells. This active N-deleted ACE contained only the first 141 amino acids of the human N-domain but not its active center and was linked to the active C-domain containing the transmembrane and cytosolic portions of ACE. The CHO cells were also transfected with human B(2) bradykinin receptor. ACE inhibitors (5 nmol/L or 1 micromol/L) augmented bradykinin (100 nmol/L) effects, elevated B(2) receptor numbers, and resensitized the receptor desensitized by agonist as measured by arachidonic acid release or [Ca(2+)](i) mobilization. Arachidonic acid release was mediated by pertussis toxin-sensitive G alpha(i), and [Ca(2+)](i) mobilization was mediated by pertussis-insensitive G alpha(q) protein receptor complex. The properties of the construct were compared with wild-type ACE and separate N- and C-domains. The N-deleted ACE differed from wild-type in activation by Cl(-) and [SO(4)](2-) ions, hydrolysis ratios of substrates (both short synthetic and endogenous peptides) and heat stability. Thus, the N-terminal peptide of ACE affected the characteristics of the C-domain active center. ACE inhibitors acting on N-deleted ACE, which had only a single C-domain active center anchored to plasma membrane, induced cross-talk between the enzyme and the B(2) receptor (eg, the inhibitors resensitized the receptor) independent of blocking bradykinin inactivation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

The characteristics of fatigue symptoms and their association with the life style and the health status in school children.

In order to evaluate the characteristics of fatigue symptoms and their association with the life style and the health status, we examined using data accumulated by the longitudinal surveys from 1992 to 1998, in 118 six-year primary school children and 129 second-year junior high school children. The complaints of "drowsiness and dullness", such as "become drowsy" (71%), "give a yawn" (59%) and "want to lie down" (51%), respectively, were most frequently observed. The proportion of these complaints was high before the first morning class, but decreased when the children leave school. Notably, the complaints of "difficulty in concentration" annually have increased. Children with undesirable eating habits, particularly those who often eat salty foods, or poor life style, such as staying up late at night tended to have more complaints of fatigue symptoms. By correlation analysis, these complaints were significantly related to the obesity degree, blood pressure, HDL cholesterol and atherogenic index. These results support the hypothesis that fatigue symptoms increase or are associated with life style and health status. Consequently, it is necessary to improve the life style such as dietary habits and rhythm of life for the reduction of fatigue symptom.

Child↗
PubMed2000

Tracking of cardiovascular risk factors and a cohort study on hyperlipidemia in rural schoolchildren in Japan.

A cohort study was conducted to explore the tracking stability of cardiovascular risk factors and relative risk (RR) of factors relating hyperlipidemia in children. The percentages of children remaining persistently at high risk over a four-year tracking were as follows: body mass index (BMI) 65.0%, total cholesterol (T-c) 60.6%, atherogenic index (AI) 56.4%, high density lipoprotein cholesterol (HDL-c) 50.7%, systolic blood pressure (SBP) 44.2% and diastolic blood pressure (DPB) 39.6%. The order of correlation coefficients over four years was BMI > AI > HDL-c > T-c > SBP > DBP and these coefficients in boys were slightly higher than those in girls. The relative risk (RR) of BMI for AI > or = 3 was elevated (RR=4.36, 95% CI: 1.3-14.1). The incidence and RR for AI > or = 3 increased along with the addition of the selected risk factor number. The RR in children with three selected risk factors rose to 8.39 ( 95% CI: 1.2-38.7 ). The stability of tracking was better for BMI, T-c, AI and HDL-c. As the number of multiple factors increased, so did the RR of higher AI in childhood. These results suggest that preventive activities for hyperlipidemia should be focused on children with multiple cardiovascular risk factors.

Cardiovascular Diseases↗
PubMed2000

[The percentage of hepatitis B virus precore A83 mutant and its dynamicchange in fulminant hepatitis B].

OBJECTIVE: In order to clarify whether hepatitis B virus precore A83 mutant is related to the pathogenesis of fulminant hepatitis B or not. METHODS: The percentage of hepatitis B virus precore A83 mutant and the quantity of HBV DNA in sera from 9 patients with fulminant hepatitis B were assayed by the method of densitometry after mispairing PCR-restriction fragment length polymorphism (mpPCR-RFLP) and quantitative PCR, respectively. RESULTS: The HBV precore A83 mutant was found in sera of 6 out of 9 (66.7%) fulminant hepatitis patients while none of them were infected with the mutant strain alone, and all were mixed with wild strain. The percentage of the mutant over fifty percent is only in 2 cases in whom one was 59.3% (survival) and another 64.8% (died). The percentage below 31.0% was in 4 cases and all of them died. It was observed that appearance or disappearance of the A83 mutant and its dynamic change of percentage were consistent with the fluctuation of HBV DNA level but there was no correlation statistically (r=0.602, 0.583; P>0.05). CONCLUSION: The mutant strain alone has little correlation to the occurrence of fulminant hepatitis. It might be merely a accompaniment to follow the replication of HBV under the highly immune pressure.

Adolescent↗
PubMed1999

Central serous chorioretinopathy: bilateral multifocal electroretinographic abnormalities.

OBJECTIVES: To assess retinal function topographically in the posterior pole of affected and fellow eyes with central serous chorioretinopathy. PARTICIPANTS AND METHODS: Multifocal electroretinograms (MERGs) were recorded from 6 patient with active central serous chorioretinopathy and 5 normal control subjects. Two patients also had full-field conventional ERGs. The MERG responses were averaged in rings radiating out from the foveal center. RESULTS: All of the patients had central macular detachments in the affected eyes, while the fellow eyes were normal except for a few small retinal pigment epithelial abnormalities. The MERG was not only depressed in areas of detachment as expected, but was also reduced beyond the area of detachment in affected eyes and throughout the posterior pole of the fellow eyes. Full-field ERGs were normal. CONCLUSIONS: The MERG findings show that there is broad retinal functional disturbance in central serous chorioretinopathy involving both eyes and areas beyond the zone of detachment. These data strongly suggest that diffuse and possibly systemic pathologic conditions underlie this disease and that the leak itself may be a somewhat incidental event. The MERG may prove useful as a clinical marker for susceptibility to serous detachment.

Adult↗
PubMed1999

The excision of polydnavirus sequences from the genome of the wasp Cotesia congregata (Braconidae, microgastrinae) is developmentally regulated but not strictly restricted to the ovaries in the adult.

Cotesia congregata polydnavirus (CcPDV) is essential for the successful parasitism of Manduca sexta larvae by the braconid wasp Cotesia congregata. In the absence of PDV, parasitoid eggs are encapsulated. Molecular analysis has demonstrated that polydnavirus sequences are integrated in the wasp chromosomes, and an ultrastructural analysis has shown that PDV replication occurs in the calyx region in the ovaries of the wasp. The bracovirus sequences appear to be excised from the wasp genome in the calyx cells where the virus replicates. Following excision of the virus sequences, the flanking sequences are rejoined. We analysed the production of two polydnavirus circles during wasp development and in different body parts of the adults of both sexes. Our study indicates that the excision of viral sequences is developmentally regulated, beginning in the pupal stage. In the adult wasp, excision occurs ubiquitously. However, regulation in the adult seems to occur only in diploid individuals, as no excision is detected in haploid males produced from virgin females.

Animals↗
PubMed1999

Sexual behaviour of commercial sex workers and their clients in Cambodia. Japan-Cambodia Collaborating Research Group.

OBJECTIVE: This study surveyed the sexual behaviour of commercial sex workers and their clients in an attempt to identify factors of transmission of STDs (including HIV/AIDS) and to control their epidemics in Cambodia and South-East Asia. DESIGN: Cross-sectional study. SETTING: Trained questioners asked items of the questionnaires to each objective subject in December 1996. Data were analysed to show the descriptive status by risk group of each person. PARTICIPANTS: 200 direct commercial sex workers, 220 indirect commercial sex workers, and 211 clients in Phnom Penh. RESULTS: Prostitution was widely accepted by both young males and females, and this was an easy way for young girls to obtain money. Although commercial sex workers and clients were knowledgeable about prevention methods against STDs, they seldom used condoms. Some commercial sex workers had been infected with STDs many times, and many of them incompletely treated the diseases by themselves. Social support from governmental and non-governmental organisation was poor. CONCLUSIONS: It is very important to support both commercial sex workers in practicing preventive methods against STDs and also visiting physicians when they notice symptoms of STDs. It is strongly recommended that not only governmental but also non-governmental organisations should be more active in this area.

Acquired Immunodeficiency Syndrome↗