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Biomedical subjects

G Tan

Publications and source records attributed to G Tan.

At least 19 recordsLinked to original sources
PubMed1999

Transcribed dinucleotide microsatellites and their associated genes from channel catfish Ictalurus punctatus.

The presence of trinucleotide microsatellites within genes is a well-known cause for a number of genetic diseases. However, the precise distribution of dinucleotide microsatellites within genes is less well documented. Here we report 15 unique cDNAs containing dinucleotide repeats from the channel catfish Ictalurus punctatus. Gene identities of nine of the 15 cDNAs were determined, of which three encode structural genes, and six encode regulatory proteins. Five cDNAs harbored dinucleotide repeats in the 5' untranslated region (5'-NTR), nine in the 3'-NTR, and one in the coding region. The presence of these transcribed dinucleotide repeats and their potential expansion in size within coding regions could lead to disruption of the original protein and/or formation of new genes by frame shift. The low number of dinucleotide repeats within coding regions suggests that they were strongly selected against. All the transcribed microsatellite loci examined were polymorphic making them useful for gene mapping in catfish.

Animals↗
PubMed1999

Omeprazole versus high-dose ranitidine in mild gastroesophageal reflux disease: short- and long-term treatment. The Dutch Reflux Study Group.

OBJECTIVE: Patients with reflux esophagitis suffer from a chronic condition that may cause considerable discomfort because of recurrent symptoms and diminished quality of life. This study was designed to evaluate acute and long-term treatment comparing standard doses of omeprazole and high-dose ranitidine. METHODS: Patients with endoscopically verified symptomatic esophagitis grade I or II were initially treated with omeprazole 20 mg daily or ranitidine 300 mg twice daily for 4-8 wk. Patients who were symptom free were randomized to maintenance treatment with omeprazole 10 mg daily or ranitidine 150 mg twice daily. Patients were seen every 3 months or at symptomatic relapse. RESULTS: The percentage of asymptomatic patients after 4 and 8 wk treatment were 61% and 74%, respectively, for omeprazole and 31% and 50%, respectively, for ranitidine. Of 446 patients treated initially, 277 were asymptomatic, of whom 263 entered the maintenance study. The estimated proportion of patients in remission after 12 months of maintenance treatment with omeprazole 10 mg daily (n = 134) and ranitidine 150 mg twice daily (n = 129) were 68% and 39%, respectively (p < 0.0001). CONCLUSIONS: Omeprazole 20 mg daily is superior to high-dose ranitidine in the symptomatic treatment of reflux esophagitis grade I and II. Furthermore, omeprazole at half the standard dose is more effective than ranitidine in a standard dose in keeping patients in remission for a period of 12 months.

Double-Blind Method↗
PubMed1998

[Primary study of differentially expressed cDNA sequences in cell line HNE1 of human nasopharyngeal carcinoma by cDNA representational difference analysis].

OBJECTIVE: To search differentially expressed sequences correlated with pathogenesis of human nasopharyngeal carcinoma (NPC), including the candidates of tumor suppressor genes. METHODS: cDNA representational difference analysis (RDA) was performed to isolate differentially expressed sequences between cDNA from normal human primary cultures of nasopharyngeal epithelial cells and cDNA from NPC cell line HNE1. The sources of differentially expressed products were proved by Southern blot and Northern blot. The fragments were cloned with pGEM-T easy kit and sequenced by the chain termination reaction. RESULTS: Four differentially expressed cDNA fragments were isolated in the fourth subtractive hybridization using cDNA from normal human primary cultures of nasopharyngeal epithelial cells as tester amplicon and cDNA from NPC cell line HNE1 as driver amplicon by cDNA RDA. These differential cDNA fragments revealed that they really came from the tester amplicon and were not expressed or down-regulated in the NPC HNE1 cells. Of these obtained clones, some are the fragments of the human known genes including house-keeping genes, the others are novel genes. CONCLUSION: NPC involves alteration of multiple genes. Some of known genes matched with the differentially expressed sequences have an effective suppressive ability on the carcinoma.

Base Sequence↗
PubMed1998

A common region of allelic loss on chromosome region 3p25.3-26.3 in nasopharyngeal carcinoma.

Loss of heterozygosity (LOH) of chromosome arm 3p has been commonly observed in carcinomas of various tissues, including those of nasopharyngeal carcinoma (NPC). To determine the frequency and extent of allelic loss in NPC, we investigated 16 loci on chromosome bands 3p21-26 in 24 tumor tissues by microsatellite analysis. LOH on 3p21-26 was found in 16 of 24 (66.7%) tumors. The highest frequency of allelic loss was found in two adjacent loci, D3S1620 (11/22, 50%) and D3S1560 (9/18, 50%). Eight cases showed LOH in one contiguous region and 5 cases in more than one region. Samples 1, 3, 4, 7, 8, 10, 16, 17, 18, 19, and 22 had a contiguous stretch of allelic loss between D3S1297 and D3S1597. The smallest common LOH/deletion region seems likely to lie between D3S1297 (3p26.3-26.2) and D3S1560 (3p25.3). The allelic loss map defined here will facilitate finer mapping of putative tumor suppressor gene loci and positional cloning of such genes, which may play a role in carcinogenesis of NPC.

Adult↗
PubMed1998

CD20 is a molecular target for scFvFc:zeta receptor redirected T cells: implications for cellular immunotherapy of CD20+ malignancy.

The CD20 molecule was evaluated as a B-cell lymphoma target epitope for T cells expressing a CD20-specific single-chain FvFc-zeta (scFvFc:zeta) chimeric receptor. A cDNA construct consisting of a murine kappa leader sequence, CD20-specific scFv, human immunoglobulin (Ig) G1 hinge-C(H)2-C(H)3, the human CD4 transmembrane, and the intracellular signaling domain of the human CD3 complex's zeta chain was synthesized by polymerase chain reaction splice-overlap extension. The human CD4+ Jurkat cell line was electroporated with the CD20-specific scFvFc:zeta construct cloned into the mammalian expression vector pcDNAneo. Western blot analysis of transfectant whole cell lysate with an anti-zeta antibody demonstrated the expression of both endogenous zeta and the chimeric receptor protein, with a mobility consistent with the expected molecular weight of 66 kD under reducing conditions; nonreduced lysate revealed a chimeric receptor complex of approximately 132 kD. The scFvFc:zeta receptor was present on the cell surface as detected by flow cytometry of T-cell transfectants stained with an anti-mouse Fab-specific antibody and anti-human Fc gamma-specific monoclonal antibody. Coculture of Jurkat transfectants with CD20+ lymphoma cells resulted in the accumulation of interleukin (IL)-2 in culture supernatants as detected by ELISA. IL-2 production was triggered by the specific interaction between the CD20 molecule and the scFvFc:zeta as IL-2 was not detected in cultures with mock transfected Jurkat cells or CD20- stimulator cells. Furthermore, IL-2 production was inhibited by the addition of a soluble anti-CD20 monoclonal antibody to cocultured Jurkat transfectants and CD20+ stimulator cells. The capacity of CD20 to trigger the lytic machinery of scFvFc:zeta-expressing cytotoxic T lymphocytes (CTLs) was assessed using the murine allo-specific CD8+ CTL clone 2c. CD20-specific redirected cytolytic activity against human lymphoma targets was observed with 2c transfectants in a 4-hour chromium release assay. These results demonstrate that CD20 can serve as a target epitope for scFvFc:zeta receptor-expressing T cells.

Antibodies, Monoclonal↗
PubMed1998

Sexuality and sexual adjustment of patients with chronic pain.

PURPOSE: To describe sexual functioning and its relationship with psychological measures in chronic pain patients. METHOD: It is a self report survey with a convenience sample. Seventy consenting chronic pain patients responded to a questionnaire. Mean age was 49.9 years (range 29-74); mean pain duration was 146.7 months (range 6-624). Participants endorsed a wide variety of pain conditions. INSTRUMENTS USED: (1) Derogatis Inventory of Sexual Functioning; (2) Multidimensional Pain Inventory; (3) Center for Epidemiological Studies Depression Scale: (4) Multidimensional Health Locus of Control; (5) Hopkins Symptom Check List; (6) Vanderbilt Pain Management Inventory; (7) Coping Strategies Questionnaire. RESULTS: Sixty-six per cent of patients were interested in sex, 50% were satisfied with current sexual partner and 20% considered current sexual life to be adequate. Over 70% fantasized at least once a month. Only 44% experienced normal arousal during intercourse; 33% practiced masturbation and 47% were involved in sexual intercourse or oral sex at least once a month. The majority were dissatisfied with orgasmic activities. No relationship was found between pain severity, duration, frequency and sexual functioning. A relationship was found between disability status, age and several psychological variables and various domains of sexual functioning. CONCLUSIONS; Sexual problems are common in chronic pain patients. Patients who reported symptoms of depression and distress had more sexual problems.

Adaptation, Psychological↗
PubMed1997

Sexuality in head and neck cancer patients.

OBJECTIVE: To describe sexual functioning and its relationship with age, extent of disfigurement, performance status, and psychological functioning in head and neck cancer patients following radiation therapy with or without surgery. DESIGN: Descriptive study, self-report survey, convenience sample. SETTING: Academic tertiary care Veterans Administration Medical Center. PATIENTS: Fifty-five of 101 consenting patients responded to the questionnaire. Mean age of the patients was 65.1 years (range 48 to 76); 54 were men. The mean duration since diagnosis was 30.6 months (range 3 to 216). All patients received radiation therapy and 26 also underwent surgery. MAIN OUTCOME MEASURES: Instruments included were: The Derogatis inventory of Sexual Functioning, Multidimensional Health Locus of Control. The Center for Epidemiological Studies Depression Scale, Hopkins Symptom Check List, and List Performance Status Scale. RESULTS: Eighty-five percent showed interest in sex. Fifty-eight percent were satisfied with their current sexual partner and 49% were satisfied with their current sexual functioning. Most of them were able to fantasize: however, a majority reported arousal problems, 58% did not participate in sexual intercourse, and 58% had orgasmic problems. Most patients were not depressed. As a group these patients reported significantly more somatic distress but significantly less generalized feeling of distress when compared with a group of nonpatient nurses. Patients with "powerful others" locus of control showed significantly worse sexual functioning. There was no correlation between sexual functioning and performance status or severity of disfigurement. Patients younger than 65 years of age had more advanced disease, lower performance status and significantly poorer sexual functioning; those older than 65 years were more satisfied with their sexual partner and current sexual functioning. CONCLUSION: Despite experiencing sexual problems, sexuality continues to be a priority in the majority of patients studied.

Aged↗
PubMed1997

Attention-deficit hyperactivity disorder. In pursuit of diagnostic accuracy.

Attention-deficit behaviors create a substantial burden for healthcare facilities. The incidence of ADHD is estimated at 5% to 10% of school-age children, but it is possible that many diagnoses of ADHD are flawed. At present, because the etiology of the disorder is not well understood, the diagnosis of ADHD by DSM-IV criteria hinges on the presence of inattention, hyperactivity, impulsivity, or a combination of these. Children who do not have ADHD also exhibit such behaviors in certain environments, as do children with learning disorders, family relational problems, and emotional difficulties. Thus it is imperative that physicians take a comprehensive approach to diagnosis when a child presents with behavioral difficulties. Noting that a number of myths about ADHD (eg, that improved behavior after being given stimulant medication proves a diagnosis of ADHD) have recently gained currency, the authors recommend going beyond the first step of behavior checklists in diagnosing the disorder and describe situations in which further assessment is indicated.

Attention Deficit Disorder with Hyperactivity↗
PubMed1997

Attention-deficit hyperactivity disorder. Pharmacotherapy and beyond.

Management of ADHD is a challenge that requires time, commitment, and great sensitivity on the part of the physician. Use of stimulant medications is often successful at improving symptoms, but it has become the knee-jerk treatment response for many. Given the wide-ranging effects of ADHD on aspects of patients' lives and the availability of various treatment alternatives, a multimodal approach is considered optimal. As more studies evaluate nonpharmacologic approaches such as behavior therapy, parent education, and neurofeedback and more physicians implement multimodal treatment, outcomes for patients with ADHD are expected to be even more positive.

Antidepressive Agents, Tricyclic↗
PubMed1997

[The spontaneous otitis media in rickety rats].

This paper is aimed to study the incidence and hearing impairment of spontaneous otitis media in rickety rats during a longterm vitamin D deficient breeding. Thirty Sprague-Dawley rats ranged from 20 to 25-day-old were used, and vitamin D deficient rickets models were established. Another thirty rats were used as the normal control. It was found that both normal and rickety rats had the possibilities of suffering from otitis media (mainly exudative) during the two-month-breeding. The incidence of otitis media in normal rats was 5% (3 from 60 ears), while that in the rickety ones was 16.67% (10 from 60 ears). It is believed that a rickety sufferer may be in higher danger of having otitis media than the normal one.

Action Potentials↗
PubMed1997

[Simultaneous determination of eight kinds of conjunct bile acids in human bile by R-HPLC].

A method for the simultaneous determination of eight kinds of conjunct bile acids in human bile was developed by HPLC. They were separated on a YWG-C18 (3 microns) column at 30 degrees C, with methanol/water (65/35, V/V, pH3.0) as mobile phase, and detection wavelength at UV 210 nm. The linear ranges were 50-1,000 microns.ml-1, the recoveries were 91.2%-108.6%. The biles of 30 cases with cholelithiasis cholecystolithiasis and 20 cases without gallstone were detected by HPLC. The results showed that the constitution of bile acids was different between patients with cholelithiasis cholecystolithiasis and patients without gallstone.

Bile↗
PubMed1996

[Endoscopic sinus surgery, clinical aspect with 69 cases].

Sixty-nine patients (121 sides) received endoscopic sinus surgery between May, 1993 and October, 1994. All of the patients exhibited following clinical signs: bilateral or unilateral nasal polyps and paranasal sinusitis. There were 43 men and 26 women, ranging in age from 14 to 68 years. Among the patients, 14 (25 sides) were treated with functional ethmoidectomy; 33 (59 sides) with total ethmoidectomy; and 21 (36 sides) with sphenoethmoidectomy. 23 patients (36 sides) were treated simultaneously with radical maxillary sinus surgery. According to the data of postoperative follow-up, nasal obstruction disappeared completely in 57 cases (57/59); headache remitted in 51 (51/56); and 35 (35/54) were free of purulent nasal discharge. No severe complications were observed. The incidence of residual and recurrent polyp were 12.39% (15/121 sides). The curative effect of endoscopic sinus surgery was analysed. The indications of operation, the preoperative CT scan of paranasal sinuses, and the endoscopic techniques were discussed.

Adolescent↗
PubMed1996

[Nasal polyps of olfactory sulcus].

To explore the origin of olfactory sulcus polyp (OSP) and observe the recovery of olfaction after functional endoscopic sinus surgery, fifty-nine olfactory sulcus polyps in 31 patients were reviewed. The origin of OSP was carefully observed. In these patients 69.5% (41 sides) originated from the mucosa of posterior ethmoid sinus, including the superior meatus (23 sides) and ethmoid cells near the ostia (18 sides). OSP originated from middle turbinate (8 sides) and superior turbinate (4 sides). Six OSP originated from the mucosa of both ethmoid and sphenoid sinus. Olfactory changes were dynamically observed after endoscopic sinus surgery in 26 patients. The smell improved significantly in 26 sides (52.0%) within three months. The olfaction improved slowly in those patients with recurrent polyps and polysinusitis associated with polyps. We suggest that minimal endoscopic sinus surgery is the treatment of choice for OSP.

Adolescent↗
PubMed1995

Diagnostic difficulties caused by a nonclamped Schizophyllum commune isolate in a case of fungus ball of the lung.

The presence of clamp connections on hyphae and the development of fruiting bodies in culture are primary characters which allow identification of the basidiomycete Schizophyllum commune in cases of human infection. The diagnostic problems presented by a nonclamped, nonfruiting isolate from a dense mass in the right upper lobe of the lung in a female with a past history of pulmonary tuberculosis and diabetes are described. Several features of the isolated fungus, including rapid growth rate and white, dense, cottony colonies, tolerance to the fungicide benomyl at a concentration of 10 micrograms/ml, and susceptibility to cycloheximide at 400 micrograms/ml, suggested that it might be a basidiomycete. Transmission electron microscopy showed the presence of a dolipore septum with perforate pore cap characteristic of fungi in the class Holobasidiomycetes. However, species identification remained elusive until compatibility tests with known single-basidiospore isolates confirmed the identification of the sterile lung isolate as S. commune. Sequence analysis of the 5' internal transcribed spacer region of ribosomal DNA further supported conspecificity.

Base Sequence↗
PubMed1994

Evaluation of patients' knowledge about anticoagulant treatment.

OBJECTIVE: To develop a questionnaire to evaluate patients' knowledge of anticoagulation. DESIGN: Anonymous self completed questionnaire study based on hospital anticoagulant guidelines. SETTING: Anticoagulant clinic in a 580 bed district general hospital in London. SUBJECTS: 70 consecutive patients newly referred to the anticoagulant clinic over six months. MAIN MEASURES: Information received by patients on six items of anticoagulation counselling (mode of action of warfarin, adverse effects of over or under anticoagulation, drugs to avoid, action if bleeding or bruising occurs, and alcohol consumption), the source of such information, and patients' knowledge about anticoagulation. RESULTS: Of the recruits, 36 (51%) were male; 38(54%) were aged below 46 years, 22(31%) 46-60, and 10(14%) over 75. 50 (71%) questionnaires were returned. In all, 40 respondents spoke English at home and six another language. Most patients reported being clearly advised on five of the six items, but knowledge about anticoagulation was poor. Few patients could correctly identify adverse conditions associated with poor control of anticoagulation: bleeding was identified by only 30(60%), bruising by 23(56%), and thrombosis by 18(36%). Only 26(52%) patients could identify an excessive level of alcohol consumption, and only seven (14%) could identify three or more self prescribed agents which may interfere with warfarin. CONCLUSION: The questionnaire provided a simple method of determining patients' knowledge of anticoagulation, and its results indicated that this requires improvement. IMPLICATIONS: Patients' responses suggested that advice was not always given by medical staff, and use of counselling checklists is recommended. Reinforcement of advice by non-medical counsellors and with educational guides such as posters or leaflets should be considered. Such initiatives are currently being evaluated in a repeat survey.

Aged↗
PubMed1993

Disseminated atypical blastomycosis in two patients with AIDS.

Two men with AIDS developed fungal infections and subsequently died as a result of dissemination of the fungal infection. Findings obtained by histologic examination, serological studies, and cultures suggested that the infections were caused by Blastomyces dermatitidis. Tissue sections showed polymorphic yeast-like cells 5-20 microns in diameter (some with broad and others with narrow single- or multiple-based buds), small yeasts, and hyphal elements. The exoantigen K positivity and exoantigen A negativity of one of the isolates indicated that the fungus was more like an African than a North American serotype.

AIDS-Related Opportunistic Infections↗
PubMed1993

Audit of start of anticoagulation treatment in inpatients.

AIMS: To develop a method for evaluating the start of anticoagulation treatment in inpatients. METHODS: One hundred case notes were audited using a proforma based on local guidelines in accordance with British Society for Haematology recommendations. RESULTS: Confirmatory investigations were done in 93% and 79% of patients with symptomatic deep venous thrombosis and pulmonary embolism, respectively. Identification of patients' risk factors for anticoagulation by history taking and laboratory tests was often inadequate: baseline coagulation screen, platelet count, liver function and renal function tests were done in 52%, 95%, 70% and 87% of cases, respectively. There was a tendency to undertreat patients: 33% of the activated partial thromboplastin times (APTT) and 58% of the International Normalised Ratios (INR) were subtherapeutic. The heparin-warfarin crossover period was particularly problematic: 37% stopped heparin without an INR that day, or had an INR of less than 2. Microscopic haematuria was monitored occasionally. Of the 62 patients continuing anticoagulation, 72% were discharged with the final INR in the therapeutic range. At discharge, only 74% of patients had documented appointments for the anticoagulant Clinic, the period between discharge and appointment ranging from 0 to 12 days. Of the 25 cases with an appointment exceeding four days after discharge, only six (24%) had arrangements for an interim INR check. CONCLUSIONS: The experience allowed the proforma to become streamlined to a more practical, reliable, and valid tool for use elsewhere. Findings will be fed back to the hospital staff to promote practice improvements before closing the audit loop by re-evaluating practice. Further studies are in progress to identify barriers experienced by doctors in implementing the guidelines and problems in the process of referral to the anticoagulant clinic.

Adult↗