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Biomedical subjects

D Y Wang

Publications and source records attributed to D Y Wang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evaluation of nasal cavity by acoustic rhinometry in Chinese, Malay and Indian ethnic groups.

Acoustic rhinometry (AR) evaluates the geometry of the nasal cavity by measuring the minimum cross-sectional area (MCA) and nasal volume (V) by means of acoustic reflection. Understanding the normal and pathologic conditions of the internal nasal cavity using AR is important in the diagnosis of structural abnormalities in patients. The aim of this study was to investigate the normal range of AR parameters in healthy volunteers from three ethnic groups in Singapore: Chinese, Malay and Indian. We also attempted to evaluate the role of these measurements in the documentation of structural abnormalities in the nose. A total of 189 Singaporeans, aged > or = 18 years, were recruited from a nationwide survey study. They comprised 83 Chinese, 35 Malays and 71 Indians. Eighty-nine subjects had a rhinoscopically normal nose (Group 1), 77 had significant septal deviation (Group 2) and 23 had inferior turbinate hypertrophy (Group 3). AR was performed to measure the MCA at the anterior 1-5 cm from the nostril and the volume (V) between points at the nostril and 5 cm into the nose. A mean MCA (mMCA; equal to (L + R)/2) and a total volume (Vt; equal to L + R) were then calculated for each subject, where L and R refer to the measurements made for the left and right nostrils, respectively. The results showed that there was no statistically significant difference in mMCA (p = 0.80) and Vt (p = 0.60) among the three ethnic subgroups of Group 1. Statistically significant differences were found only between Groups 1 and 3 (p < 0.001 for both mMCA and Vt) and between Groups 2 and 3 (p = 0.001 for mMCA and p = 0.013 for Vt). Although there was no significant difference between Groups 1 and 2, significant differences in MCA (p = 0.001) and V (p = 0.040) were found between the narrower sides (smaller volume) and the wider sides in Group 2, indicating volume compensation between the nasal cavities. In conclusion, our study demonstrates that there is no significant difference in the normal range of AR measurements among Chinese, Malay and Indian ethnic groups. AR is able to determine the structural abnormality of the internal nasal cavity caused by septal deviation and inferior turbinate hypertrophy.

Acoustics↗
PubMed2001

Possible cofactor in cervical carcinogenesis: proliferation index of the transformation zone in cervicitis.

BACKGROUND: Most cervical cancers arise from the transformation zone. Human papillomavirus (HPV) has been identified as playing a central role in cervical carcinogenesis. However, the lengthy period from initial HPV infection through the precancerous stage to cancer lesions implicates that the cofactors involved in the process might be random events. Our study was designed to study the relationship between the cell mitotic index and tissue inflammation of the uterine cervix. The results may help to explain the role of chronic inflammation as a possible cofactor of cervical carcinogenesis. METHODS: Using Ki-67 immunostaining, the proliferation index (PI) was determined in 30 cervices removed in hysterectomies for non-cervical diseases. The chronic cervical inflammation was graded according to quantification of inflammatory cells in adjacent stromal tissue. The relationships of these two parameters within the exocervix, the transformation zone (T-zone) and the endocervix were analyzed and their differences were compared. RESULT: A significant correlation between the microscopic inflammation scale and the PI was found in the T-zone of the cervix (p = 0.034). The PI of the T-zone, exocervix and endocervix were significantly different (p < 0.001) with scores of 66.1 (SD 26.3), 41.6 (SD 23.3) and 7.1 (SD 5.0), respectively. CONCLUSION: The results, based on modern cellular evidence, explain, at least partially the observation that cervical cancer occurs predominantly in the T-zone and suggest that implementation of antibiotic treatment in selected human papillomavirus-infected patients might decrease the development of cervical cancer.

Cell Division↗
PubMed2001

Pattern of sensitization to common environmental allergens amongst atopic Singapore children in the first 3 years of life.

This study was aimed to investigate the sensitization pattern to a range of common allergens in young Singaporean children. A cross-sectional study involving 75 children aged below 3 years was carried out. They presented between December 1995 and April 2000 with symptoms of asthma, rhinitis, eczema, or food allergy. Their levels of allergen-specific serum IgE to a panel of foods (egg white, milk, soy protein, shrimp, wheat and peanut), pet dander, dust mites and cockroaches were measured with Pharmacia CAP System radioallergosorbent test kits. Serum IgE levels greater than 0.35 kU/l represented a positive result. Four children could not be tested with the complete panel because of insufficient serum. The prevalence of sensitization was highest for cow's milk (45.9%) followed by egg white (38.7%), dust mites Dermatophagoides pteronyssinus (31.4%) and Blomia tropicalis (25.5%). Sensitization to ingested allergens was significantly more prevalent in children aged 1 year or younger than in the older children (70.4% of those below 1 year, and 50% of those aged 1-3 years; p < 0.02). Sensitization to inhaled allergens, such as dust mites, was more likely to manifest as respiratory symptoms (allergic rhinitis and asthma), while ingested allergens were associated with gastrointestinal symptoms and eczema (p < 0.001). It was concluded that infants and young children are at high risk of sensitization to common environmental substances. Allergen avoidance is therefore important even in the very young. The prevalence of sensitization to food allergens is higher compared to inhalant allergens in young children.

Allergens↗
PubMed2000

Receptor for the pain modulatory neuropeptides FF and AF is an orphan G protein-coupled receptor.

Opiate tolerance and dependence are major clinical and social problems. The anti-opiate neuropeptides FF and AF (NPFF and NPAF) have been implicated in pain modulation as well as in opioid tolerance and may play a critical role in this process, although their mechanism of action has remained unknown. Here we describe a cDNA encoding a novel neuropeptide Y-like human orphan G protein-coupled receptor (GPCR), referred to as HLWAR77 for which NPAF and NPFF have high affinity. Cells transiently or stably expressing HLWAR77 bind and respond in a concentration-dependent manner to NPAF and NPFF and are also weakly activated by FMRF-amide (Phe-Met-Arg-Phe-amide) and a variety of related peptides. The high affinity and potency of human NPFF and human NPAF for HLWAR77 strongly suggest that these are the cognate ligands for this receptor. Expression of HLWAR77 was demonstrated in brain regions associated with opiate activity, consistent with the pain-modulating activity of these peptides, whereas the expression in adipose tissue suggests other physiological and pathophysiological activities for FMRF-amide neuropeptides. The discovery that the anti-opiate neuropeptides are the endogenous ligands for HLWAR77 will aid in defining the physiological role(s) of these ligands and facilitate the identification of receptor agonists and antagonists.

Amino Acid Sequence↗
PubMed2000

Inositol phosphoglycans and signal transduction systems in pregnancy in preeclampsia and diabetes: evidence for a significant regulatory role in preeclampsia at placental and systemic levels.

Measurements have been made of the urinary content of inositol phosphoglycans IPG P-type and IPG A-type, putative insulin second messengers, in preeclampsia, in type I insulin-treated diabetic pregnant women and their matched control subjects, and nonpregnant women of child-bearing age. The content of IPG P-type and IPG A-type was also measured in the placenta from preeclamptic patients and from normal pregnancies. Pregnancy was associated with an increase, approximately twofold, in urinary output of IPG-P-type relative to nonpregnant controls (P<0.01). The 24-h output of IPG P-type in urine in preeclamptic women was significantly higher (2- to 3-fold) than in pregnant control subjects matched for age, parity, and stage of gestation (P<0.02). In contrast, insulin-dependent diabetic pregnant women did not show any significant change in urinary output of IPG P-type or IPG A-type relative to pregnant control subjects. Evidence for a possible relationship and correlation between the urinary excretion of IPG P-type and markers of preeclampsia, including proteinuria (r = 0.720, P<0.01), plasma aspartate transaminase (r = 0.658, P<0.05), and platelet counts (r = 0.613, P<0.05) is presented. A high yield of IPG P-type was extracted from human placenta, in preeclampsia some 3-fold higher (P = 0.03) than the normal value, whereas no IPG A-type (with lipogenic-stimulating activity) was found. Low concentrations of placental IPG A-type were detected relative to IPG P-type using assay systems dependent upon the effect of this mediator on cAMP-dependent protein kinase or on a proliferation assay using thymidine incorporation into DNA of EGFR T17 fibroblasts. It is postulated that the high urinary excretion IPG P-type in preeclampsia reflects high placental levels and relates to the accumulation of glycogen in the placenta. The paracrine effects of placental IPG P-type (stimulation off other endocrine glands and/or endothelial cells) could contribute to the pathogenesis of the maternal syndrome. A possible theoretical link between elevated placental IPG P-type and apoptosis is proposed.

Adult↗
PubMed2000

Inositol phosphoglycans and the regulation of the secretion of leptin: in vitro effects on leptin release from adipocytes and the relationship to obesity.

The ratio of two families of inositol phosphoglycans (IPG-A:IPG-P), insulin second messengers, is raised in non-insulin-dependent diabetes mellitus (NIDDM) and obesity. It is shown here that IPG A type inhibits leptin release from adipocytes, contrasting with the action of insulin (stimulation) and IPG P type (no effect). The significance of inhibitory effects of IPG A type on leptin release is important in relation to obesity and NIDDM in view of the action of leptin in promoting Lep expression and fat oxidation in muscle, in addition to its effects on satiety. Energy conservation and oxidation via interorgan regulation by leptin could be compromised by a rise in the IPG-A:IPG-P ratio.

Adipocytes↗
PubMed2000

Isolation and localization of type IIb Na/Pi cotransporter in the developing rat lung.

Differential display analysis of rat lung at different developmental stages identified a fragment, HG80, which appeared on embryonic day 16.5 and thereafter. A full-length cDNA derived from a cDNA library of newborn rat lung probed with HG80 was the rat counterpart of sodium-dependent phosphate transporter type IIb and was designated rNaPi IIb. In situ hybridization showed that rNaPi IIb was expressed in type II alveolar cells, suggesting a role in the synthesis of surfactant in the alveoli. The time-dependent changes in localization of this gene in the developing lung and its possible use as a type II pneumocyte marker are discussed.

Animals↗
PubMed2000

Serial antinuclear antibodies titre in pleural and pericardial fluid.

The antinuclear antibodies (ANA) test has been a cornerstone of the evaluation of connective tissue disease. The aim of this study was to investigate the diagnostic value of the ANA test in pleural or pericardial effusions of unknown causes. Over a 3-yr period, a total of 126 pleural fluid and 30 pericardial fluid samples were analysed. ANA tests were performed using a commercially available kit. The ANA kit used an indirect immunofluorescent antibody method with a human epithelial (HEP-2) cell line as substrate. Patients with high fluid ANA titre (>1:160) received a second aspiration 2 weeks after the initial aspiration if diagnosis was not confirmed. ANA results were positive in 39 pleural and 10 pericardial fluid samples. All but one of the effusions with positive ANA testing were exudative. Eleven pleural or pericardial effusions due to active systematic lupus erythematosus were identified and all had high ANA titres (1:160) with various staining patterns. Thirty-eight of 145 patients (26%) with effusions of nonlupus aetiologies had positive ANA testing in pleural or pericardial fluid. Thirteen of these 38 patients had high ANA titre. Malignant or paramalignant effusions constituted 11 of the 13 samples. In conclusion, although a negative antinuclear antibodies test makes a diagnosis of lupus serositis unlikely, high antinuclear antibodies titres in pleural or pericardial fluid are not diagnostic of lupus serositis even when as high as 1:5,120. An unexplained high antinuclear antibodies titre in pleural or pericardial effusion warrants search for malignancy.

Adolescent↗
PubMed2000

Mxi1 is a potential cellular target of carcinogens and frequently mutated in experimental rat tumors and tumor cell lines.

Mxi1, a member of the Myc family of transcription factors, negatively regulates Myc oncoprotein activity and thus may be a tumor suppressor gene. It is mutated in a few human prostate cancers. Rat Mxi1 was isolated as a selective overexpressive message in rat esophageal cancer induced by N-nitrososarcosine ethyl ester using differential display and polymerase chain reaction cloning. Reverse transcription, single-strand conformation polymorphism analysis and subsequent DNA sequencing were used to screen mutations for the rat Mxi1 coding region including the functional domains, Sin3-interacting, helix-loop-helix and leucine zipper in samples from 24 rat tumor tissues and various cell lines. Seven mutations were revealed to exist in six rat tumors (including two esophageal tumors and a breast cancer), and three rat tumor cell lines: Leydig cell tumor, osteogenic sarcoma, and pituitary tumor. No coding changes were detected in 34 samples of human sporadic gastric adenocarcinoma. A silent base substitution (GAG to GAA) at codon 131 was also identified in six rat tumors as well as in one human gastric cancer. Our results indicate that Mxi1 is often mutated in experimental rat tumors but mutations are rare in human sporadic cancers. The Mxi1 tumor suppressor gene may be a cellular target of strong carcinogens. Considering the frequency of mutations in chemical carcinogen-induced tumors, searches for Mxi1 mutation in human tumors should be directed toward patients with a specific epidemiological background.

Adenocarcinoma↗
PubMed2000

Modulation of oestrone sulphate formation and hydrolysis in breast cancer cells by breast cyst fluid from British and Hungarian women.

Women with gross cystic breast disease may have an increased risk of breast cancer. In this study the ability of breast cyst fluid (BCF), obtained from British or Hungarian women, to modulate oestrone sulphate (E1S) formation or hydrolysis, has been examined. For this, oestrogen receptor-positive (ER+) MCF-7 or MDA-MB-231 (ER-) breast cancer cells were employed. The formation and hydrolysis of E1S was measured using radiometric techniques. BCF from British and Hungarian women mainly inhibited E1S hydrolysis in MCF-7 cells while stimulating hydrolysis in MDA-MB-231 cells. The extent of inhibition or stimulation of E1S hydrolysis in these cells was related to the Na+/K+ ratio of the BCF. There was a significant inverse relationship between the extent to which BCF samples inhibited hydrolysis in MCF-7 cells and stimulated it in MDA-MB-231 cells. BCF stimulated E1S formation in MCF-7 cells while inhibiting formation in MDA-MB-231 cells. No difference in the ability of BCF from British or Hungarian women to inhibit or stimulate E1S hydrolysis was detected in ER+ or ER- breast cancer cells. In contrast, BCF from British women stimulated E1S formation in ER+ cells (median 82%) to a significantly greater extent (P < 0.01) than BCF from Hungarian women (median 33%). The role that E1S has in breast cancer development remains unclear. The greater stimulation of E1S formation by BCF from British women, who have a higher risk of breast cancer than Hungarian women, suggests that it may act as a storage form of oestrogen within cells that can be activated by oestrone sulphatase.

Breast Neoplasms↗
PubMed2000

Urinary androgens and breast cancer risk: results from a long-term prospective study based in Guernsey.

Between 1961 and 1967 a cohort of over 5000 women volunteered for a prospective study to determine the relationship between the urinary androgen metabolites, androsterone (A) and aetiocholanolone (E), and risk of breast cancer. During the first 10 years of the study the concentration of urinary A and E was determined in 1887 of the urine specimens. In 1971 we reported that subnormal amounts of urinary A and E were associated with a significantly increased risk of breast cancer. The cohort has been followed regularly during the 37 years since inception of the study and, by May 1998, 248 women had been diagnosed with breast cancer. Urinary androgen metabolites had been measured in 116 of these cases. Analysis of these data confirmed that women diagnosed in the first decade of the study were more likely to have low levels of urinary androgen metabolites. In the following decades, however, those who developed breast cancer were more likely to have manifested an increased A and E excretion. The reversal in the relationship between androgen metabolite excretion and risk suggests that age, or probably more importantly, menopausal status at diagnosis is an important modifying factor. Dichotomizing at age 50 it was found that in the younger age group (predominantly premenopausal) the rate ratios in the lowest tertile of A or E excretion were two- to threefold greater than for those in the highest tertile (chi2(1) = 3.57; P = 0.06: chi2(1) = 4.70; P = 0.03 for A and E respectively). In contrast, in the older age group comprising predominantly post-menopausal women, the rate ratios associated with the lowest tertile of A or E were half that of those in the highest tertile (chi2(1) = 4.10; P = 0.04; chi2(1) = 8.72; P = 0.003 for A and E respectively). This suggests that there may be different endocrine promotional factors for pre-and post-menopausal breast cancer. Hormonal risk factors may vary during the lifetime of an individual woman and this may have profound consequences for prevention strategies.

Age Factors↗
PubMed2000

MDM2 overexpression with alteration of the p53 protein and gene status in oral carcinogenesis.

In this study, to better understand the mechanism of oral squamous cell carcinoma (SCC) carcinogenesis, alterations of the p53 gene and overexpression of MDM2 and p53 were analyzed in 38 oral SCC samples. Twelve of the 38 specimens revealed mutant-type p53. Moreover, coexpression of MDM2 and p53 was found most frequently in dysplastic lesions (P < 0.05). Expression of MDM2 and p53 was significantly increased in accordance with the histological progression of multistep carcinogenesis (P < 0.05). No significant correlation was found between the expression of MDM2 and the alteration of p53 protein or p53 gene status. MDM2 overexpression with mutant p53 was significantly associated with poorly differentiated SCCs (P < 0.05) and tumor stages III and IV of oral SCCs (P < 0.05). These results suggest that MDM2 overexpression is an early event in oral carcinogenesis through the functional inactivation of the wild-type p53, and corresponding alterations of MDM2 and p53 contribute to the oral carcinogenesis. We propose that it would be clinically more instructive to evaluate MDM2 overexpression combined with p53 gene status, compared to the evaluation of either MDM2 or p53 alteration alone.

Carcinoma, Squamous Cell↗
PubMed2000

Evidence that the proposed novel human "neurokinin-4" receptor is pharmacologically similar to the human neurokinin-3 receptor but is not of human origin.

There have been proposals that the tachykinin receptor classification should be extended to include a novel receptor, the "neurokinin-4" receptor (NK-4R), which has a close homology with the human NK-3 receptor (hNK-3R). We compared the pharmacological and molecular biological characteristics of the hNK-3R and NK-4R. Binding experiments, with (125)I-[MePhe(7)]-NKB binding to HEK 293 cell membranes transiently expressing the hNK-3R (HEK 293-hNK-3R) or NK-4R (HEK 293-NK-4R), and functional studies (Ca(2+) mobilization in the same cells) revealed a similar profile of sensitivity to tachykinin agonists and antagonists for both receptors; i.e., in binding studies with the hNK-3R, MePhe(7)-NKB > NKB > senktide >> NKA = Substance P; with the NK-4R, MePhe(7)-NKB > NKB = senktide >> Substance P = NKA; and with antagonists, SB 223412 = SR 142801 > SB 222200 >> SR 48968 >> CP 99994 for both hNK-3R and NK-4R. Thus, the pharmacology of the two receptors was nearly identical. However, attempts to isolate or identify the NK-4R gene by using various molecular biological techniques were unsuccessful. Procedures, including nested polymerase chain reaction studies, that used products with restriction endonuclease sites specific for either hNK-3R or NK-4R, failed to demonstrate the presence of NK-4R in genomic DNA from human, monkey, mouse, rat, hamster, or guinea pig, and in cDNA libraries from human lung, brain, or heart, whereas the hNK-3R was detectable in the latter libraries. In view of the failure to demonstrate the presence of the putative NK-4R it is thought to be premature to extend the current tachykinin receptor classification.

Binding, Competitive↗
PubMed2000

Comparison of different diagnostic methods for lupus pleuritis and pericarditis: a prospective three-year study.

BACKGROUND AND PURPOSE: Pleural or pericardial effusions, or both, are commonly encountered, but the differential diagnosis is sometimes difficult. We evaluated the diagnostic value of effusion immunofluorescent antinuclear antibody (ANA) titer, systemic lupus erythematosus (SLE) latex agglutination slide test, and cytologic LE cell examination in patients with pleural and/or pericardial effusions of various etiologies. METHODS: A total of 153 pleural and/or pericardial effusion specimens were collected by aspiration from 152 patients (14 SLE and 138 non-SLE patients). All specimens were sent for routine biochemistry testing, determination of ANA titer, SLE latex agglutination slide test, and LE cell examination. RESULTS: Ten of the 14 SLE patients had lupus serositis and all of them had high ANA titers (> or = 1:160) in their effusions. SLE latex and LE cell tests were positive in seven and eight patients with lupus serositis, respectively. The remaining four SLE patients with effusion of etiologies other than lupus serositis had low or negative effusion ANA titers. Among the non-SLE patients, 29 of 112 patients (26%) with pleural effusion and six of 26 patients (23%) with pericardial effusion had positive ANA tests (> or = 1:40). None of them had a positive SLE latex or LE cell test result. Thirteen of the 138 non-SLE patients (11%) had high effusion ANA titers (> or = 1:160). Effusion in 11 of 13 non-SLE patients (85%) was due to malignancy. CONCLUSIONS: Effusion ANA titer detection is a very sensitive but nonspecific test for the diagnosis of lupus serositis. SLE latex and cytologic LE cell tests can aid in the differential diagnosis as complementary tools. The specificity, positive and negative predictive values of these two tests are excellent for the diagnosis of lupus serositis.

Adolescent↗
PubMed2000

[FruA, a transcription factor in Myxococus xamthus, regulates transcription of target genes in collaboration with the associated protein FruB].

Many developmental genes are regulated by FruA, a transcription factor essential for the development of Myxococus xamthus. Another protein, designated FruB, was purified from myxobacteria by its affinity to FruA. FruB could be phosphorylated by protein kinase(s) located in cell membrane. Gel shift assay showed that FruA regulates transcription of target genes in collaboration with phosphorylated FruB. This study may shed light on the molecular mechanisms of regulatory network involved in the development of Myxococus xamthus.

Bacterial Proteins↗
PubMed2000

[The detection and analysis of human papillomavirus in infantile respiratory tract papillomas by PCR/RFLP study].

OBJECTIVE: To study the relationship between human papillomavirus (HPV) and pathological characteristics of the patients with infantile respiratory tract papillomas (IRP). METHOD: Thirteen cases of infantile respiratory tract papillomas tissue were analysed for Papillomavirus by the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). RESULT: The amplified products of the HPV-L1 region by PCR by using the consensus primers showed that the presence of HPV was 100 percent. Eight cases(61.5 percent) were positive for HPV6 only. Four cases (30.8 percent) were positive for HPV11 only. One case (7.7 percent) showed the presence of HPV18. None were positive for HPV16, 31, 33, 52, 58. CONCLUSION: Infantile respiratory tract papillomas are associated with HPV6, 11, 18 infection, but the subtypes of HPV are not associated with clinical pathological characteristics.

Child, Preschool↗
PubMed1999

alphaPIX nucleotide exchange factor is activated by interaction with phosphatidylinositol 3-kinase.

p21-activated kinase (PAK) is a common effector protein of the small GTPases Cdc42 and Rac, leading to the activation of downstream mitogen activated protein kinases. PAK also mediates polarized cytoskeletal changes induced by these GTPases. The recently identified PAK-interacting exchange factor (PIX) acts as a guanine nucleotide exchange factor on Rac, and colocalizes with PAK in a focal complex, but little is known about the associated signaling cascades, including upstream activators of PIX. In this study, we show that one of the isoforms of PIX, alphaPIX, is activated by signaling cascades from the platelet-derived growth factor (PDGF) receptor and EphB2 receptor, and from integrin-induced signaling through phosphatidylinositol 3-kinase (PI3-kinase). alphaPIX is activated by forming a complex with these receptors either via association with PAK and Nck, or direct association with the p85 regulatory subunit of PI3-kinase. Synthetic phosphoinositide and membrane targeted PI3-kinase augmented the alphaPIX activity in vivo. In Xenopus, aggregates of mesodermal cells derived from embryos microinjected with alphaPIX significantly increased the peripheral spreading on fibronectin substrate in response to PDGF through PI3-kinase. These results indicate that alphaPIX is activated by PI3-kinase, and is involved in the receptor mediated signaling leading to the activation of the kinase activity of PAK, and the migration of mesodermal cells on extracellular matrix.

Adaptor Proteins, Signal Transducing↗