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Biomedical subjects

G Tan

Publications and source records attributed to G Tan.

At least 37 records · Page 2Linked to original sources
PubMed1999

cDNA representational difference analysis of differentially expressed cDNA sequences in human nasopharyngeal carcinoma.

OBJECTIVE: To search differentially expressed sequences correlated with pathogenesis of human nasopharyngeal carcinoma (NPC), including the candidates of tumor suppressor genes. METHODS: 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 source of differentially expressed products were proved by Southern blot, Northern blot and in situ hybridization. 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 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. Some of the genes were expressed only in human nasopharyngeal epithelial cells but deleted or down-regulated in the biopsies of NPC. Of these obtained clones, some were the sequences of the human known genes including house-keeping genes, the others represented novel gene sequences. CONCLUSION: The differentially expressed products including the candidates of tumor-suppressor genes may be associated with the initiation of the NPC.

DNA, Complementary↗
PubMed1999

[Study on cytotoxicity to leukemia cell and enhancement of immunologic functions of jiexinkang].

Cytotoxicity to leukemia cell and enhancement of immunologic functions of jiexinkang (JXK, traditional Chinese medicine) were observed in 34 cases of leukemia in vitro. The results showed that the leukemia cytotoxicity in the group of vincristine combined with JXK was significantly higher than that in vincristine alone. It was also found among all the observed cases that 20 refractory or recurred patients resistant to vincristine showed an obvious intention of the anti-toxicity efficiency when JXK was added. Jiexinkang alone had anti-leukemia cell effect, too. We explored JXK effects on immunologic functions in mice, and found that IFNr and NK activities of normal and experimental model mice were significantly higher than those of control group(P < 0.01). The results indicate that JXK has an effect of anti-leukemia cell and may improve the cell-immunologic functions.

Adjuvants, Immunologic↗
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↗
PubMed1998

[Complications of endoscopic sinus surgery: incidence and prevention-analysis of 307 cases].

The complications of endoscopic sinus surgery performed on 307 patients with chronic inflammatory paranasal sinus diseases were analysed. The results showed that: 1. The common complications were excessive bleeding, orbit penetration, intra-orbital haemorrhage, postoperative stenosis of the maxillary ostium and middle turbinate adhesions. 2. The most common perioperative complications were those related to orbital penetration except excessive bleeding. A major complication was a case of cerebrospinal rhinorrhea with secondary purulent meningitis. 3. The annual overall incidences and the rates of common complications have been significantly decreased with year. The causes and prevention of excessive bleeding, stenosis of maxillary ostium and middle turbinate adhesions are discussed emphatically. In addition, the proposals were offered concerning the diagnostic criteria of the complications, and the statistical method of the complication incidence.

Adolescent↗
PubMed1998

[Allelic loss on chromosome 3p21-26 in nasopharyngeal carcinoma].

OBJECTIVE: To determine the frequency and extent of loss of heterozygosity (LOH) on chromosome 3p in nasopharyngeal carcinoma (NPC). METHODS: Sixteen loci on chromosome bands 3p21-26 in 24 tumors was studied by using microsatellite analysis. RESULTS: LOH on 3p21-26 was found in 16 of 24 tumors (66.7%). The highest frequency of the allelic loss was found in two adjacent loci D3S1620(50%, 11/22) and D3S1560 (50%, 9/18). Eight cases showed LOH in one contiguous region and 5 cases in more than one region. Sample 1, 3, 4, 7, 8, 10, 16, 17, 18, 19, and 22 had a contiguous stretch of allelic loss between D3S1297 and D3S1597. CONCLUSION: The smallest common LOH/deletion region seems likely to lie between D3S1620(3p26.2-26.3) 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

[Ostium of maxillary sinus in endoscopic sinus surgery].

OBJECTIVE: To determine the clinical significance and operative method of maxillary sinus ostium in the treatment of chronic sinusitis and nasal polyps. METHODS: Fifty-six patients (112 sides) undergone endoscopic sinus surgery were studied. RESULTS: The patency rates of the maxillary ostia in patients with enlarged and unchanged maxillary ostia were 92.9% and 80.4% respectively. Fifty-one patients (64 sides) undergone Caldwell-Luc operations were retrospectively studied. The patency rate of inferior antrostomy was 40.6%. CT scans of the sinuses of 38 cases with unilateral sinisitis or nasal polyps were reviewed. The scaled values of the maxillary hiatus on CT images showed no difference between the normal group and the diseased group. Pneumatization and proliferation of middle turbinate and bent uncinate process were the most common anatomic variation in the diseased group. CONCLUSION: The results suggest that management of anatomic variations surrounding the ostia is very important in the treatment of maxillary ostium.

Adolescent↗
PubMed1998

[The influence of porcelain-fused-to-metal crown margin to the aesthetics of gingiva].

The gingival tissue of 76 anterior teeth which were hurt by margin of porcelain-fused-to-metal (PFM) crowns were analyzed and the reasons of the gingival hurt and the precaution methods were put forward. The unsuccessful PFM crowns were replaced with new crowns and 88.16% of them are better than before. As the result, the gingival margin health of anterior teeth is the important factor which keep the esthetics of teeth, and the right clinical process is crucial to maintain the natural aesthetics of gingival margin.

Adult↗
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↗