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Biomedical subjects

W Wen

Publications and source records attributed to W Wen.

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

Islet beta cell expression of constitutively active Akt1/PKB alpha induces striking hypertrophy, hyperplasia, and hyperinsulinemia.

The phosphoinositide 3-kinase-Akt/PKB pathway mediates the mitogenic effects various nutrients and growth factors in cultured cells. To study its effects in vivo in pancreatic islet beta cells, we created transgenic mice that expressed a constitutively active Akt1/PKB alpha linked to an Insulin gene promoter. Transgenic mice exhibited a grossly visible increase in islet mass, largely due to proliferation of insulin-containing beta cells. Morphometric analysis verified a six-fold increase in beta cell mass/pancreas, a two-fold increase in 5-bromo-2'-deoxyuridine incorporation, a four-fold increase in the number of beta cells per pancreas area, and a two-fold increase in cell size in transgenic compared with wild-type mice at 5 weeks. At least part of the increase in beta cell number may be accounted for by neogenesis, defined by criteria that include beta cells proliferating from ductular epithelium, and by a six-fold increase in the number of single and doublet beta cells scattered throughout the exocrine pancreas of the transgenic mice. Glucose tolerance was improved, and fasting as well as fed insulin was greater compared with wild-type mice. Glucose-stimulated insulin secretion was maintained in transgenic mice, which were resistant to streptozotocin-induced diabetes. We conclude that activation of the Akt1/PKB alpha pathway affects islet beta cell mass by alteration of size and number.

Animals↗
PubMed2001

Sulfotransferase 1A1 polymorphism, endogenous estrogen exposure, well-done meat intake, and breast cancer risk.

Sulfotransferase (SULT) 1A1 is involved in the inactivation of estrogens and bioactivation of heterocyclic amines and polycyclic aromatic hydrocarbons. A G--->A transition at codon 213 (CGC/Arg to CAC/His) of the SULT1A1 gene was reported recently, and individuals homozygous for the His allele have a substantially lower activity of this enzyme than those with other genotypes. We hypothesized that the His allele may be a risk factor for breast cancer, particularly among women who had risk factors related to higher endogenous estrogen exposure. This hypothesis was investigated in a case-control study conducted in a cohort of postmenopausal Iowa women who completed a mailed questionnaire in 1986 on lifestyle factors including information on major breast cancer risk factors. DNA samples and information related to well-done meat intake were obtained from breast cancer cases diagnosed between 1992 and 1994 and a random sample of cancer-free cohort members. Multivariate analysis was performed on data from 156 cases and 332 controls who donated a blood sample. The frequency of the His allele was 41.6% in cases and 34.1% in controls (P = 0.03), and the risk of breast cancer was increased with the number of His alleles (P for trend = 0.02). Compared with women with the Arg/Arg genotype, an 80% elevated risk was observed among women homozygous for the His allele (95% confidence interval, 1.0-3.2; P = 0.04). This positive association was more pronounced among women who drank alcohol and had a high body mass index, early age at menarche, and late age at menopause, factors related to high endogenous estrogen exposure, than among those who did not have these risk factors. The risk of breast cancer was elevated with increasing doneness level of red meat intake among women with the Arg/Arg genotype (P for trend, 0.01) or the Arg/His genotype (P for trend, 0.10), whereas this association was not evident for women with the His/His genotype. The results from this study suggest that homozygosity for the SULT1A1 His213 allele may be a risk factor for breast cancer, and its effect may be modified by the exposure level of endogenous estrogens and heterocyclic amines.

Age Distribution↗
PubMed2001

Soyfood intake during adolescence and subsequent risk of breast cancer among Chinese women.

Many experimental but few epidemiological studies have suggested that soyfoods and their constituents have cancer-inhibitory effects on breast cancer. No epidemiological study has evaluated the association of adolescent soyfood intake with the risk of breast cancer. To evaluate the effect of soyfood intake during adolescence, one of the periods that breast tissue is most sensitive to environmental stimuli, on subsequent risk of breast cancer, we analyzed data from a population-based case-control of 1459 breast cancer cases and 1556 age-matched controls (respective response rates were 91.1% and 90.3%). Information on dietary intake from ages 13-15 years was obtained by interview from all study participants and, in addition, from mothers of subjects less than 45 years of age (296 cases and 359 controls). Odds ratios (ORs) and 95% confidence intervals (CIs) derived from unconditional logistic models were used to measure soyfood intake and breast cancer risk. After adjustment for a variety of other risk factors, adolescent soyfood intake was inversely associated with risk, with ORs of 1.0 (reference), 0.75 (95% CI, 0.60-0.93), 0.69 (95% CI, 0.55-0.87), 0.69 (95% CI, 0.55-0.86), and 0.51 (95% CI, 0.40-0.65), respectively, for the lowest to highest quintiles of total soyfood intake (trend test, P < 0.001). The inverse association was observed for each of the soyfoods examined and existed for both pre- and postmenopausal women. Adolescent soyfood intakes reported by participants' mothers were also inversely associated with breast cancer risk (P for trend < 0.001), with an OR of 0.35 (95% CI, 0.21-0.60) for women in the highest soyfood intake group. Adjustment for rice and wheat products, the major energy source in the study population, and usual adult soyfood intake did not change the soyfood associations. Our study suggests that high soy intake during adolescence may reduce the risk of breast cancer in later life.

Adolescent↗
PubMed2001

[Application of video laryngoscope in diagnosis and treatment of laryngeal diseases].

OBJECTIVE: To investigate the value of video laryngoscope in diagnosis of laryngeal diseases. To study the effect of video laryngoscope in treatment of laryngeal diseases. METHOD: Pentax VNL-1530T and Olympus BF-240T video laryngoscope were used in diagnosis of 3628 cases of laryngeal diseases and in treatment of 1221 cases of laryngeal diseases. RESULT: 3628 cases were examined by video laryngoscope, and correct diagnosis was made. 768 cases of vocal cord polyp and 249 cases of vocal cord node were excised, 113 cases of foreign bodies in hypopharynx or larynx were removed. 91 cases of other laryngeal diseases were treated under video laryngoscope. CONCLUSION: Video laryngoscope is a new excellent instrument in diagnosis and treatment of laryngeal disease.

Adolescent↗
PubMed2000

Planar magnetic colloidal crystals.

We report a novel form of planar magnetic colloidal crystals formed by coated magnetic microspheres floating on a liquid meniscus. Under an external magnetic field, the balance between the repulsive magnetic interaction and the "attractive" interaction, due to the weight of the particles projected along the surface tangent, yields not only the triangular lattice with a variable lattice constant, but also all the other planar crystal symmetries such as the oblique, centered-rectangular, rectangular, and square lattices. By using two different sized magnetic particles, local formations of 2D quasi-crystallites with fivefold symmetry are also observed.

Journal Article↗
PubMed2000

Cyclic AMP activates Ras.

In addition to protein kinase A (PKA), cAMP regulates the activity of cAMP-gated channels and Rap1-specific guanine nucleotide exchange factors. We tested the hypothesis that the targets of cAMP might also include regulators of the Ras protooncogene. In rat thyroid cells, thyrotropin (TSH) stimulates proliferation through a cAMP-mediated pathway that requires Ras activity. Interference with Ras impairs DNA synthesis stimulated by TSH as well as cAMP elevating agents and analogs, demonstrating that the requirement for Ras lies down-stream of cAMP. Although cAMP stimulates proliferation, microinjection of the purified PKA catalytic subunit failed to do so, suggesting that factors in addition to PKA are required for cAMP-stimulated cell cycle progression. When added to thyroid cells expressing human Ha-Ras, TSH rapidly and markedly increased the proportion of GTP-bound Ras. Ras activity was increased within 1 min of TSH addition, maximal at 5-15 min, and declined to basal levels 30-60 min after hormone treatment. Cyclic AMP elevating agents elicited similar effects on Ras, indicating that TSH activates Ras through a cAMP-mediated pathway. Although cAMP-mediated, Ras activation by TSH and cAMP was independent of PKA activity. Moreover, cAMP-stimulated Ras activation was not impaired by tyrosine kinase inhibitors. These results indicate that cAMP activates targets in addition to PKA in thyroid cells, and that these targets may include regulators of Ras. The ability of cAMP elevating agents to activate Ras in addition to PKA may explain the inability of the PKA catalytic subunit to stimulate DNA synthesis in thyroid cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2000

Association of menstrual and reproductive factors with breast cancer risk: results from the Shanghai Breast Cancer Study.

The incidence of breast cancer among women in Shanghai, a traditionally low-risk population, has increased substantially over the past 20 years. To evaluate the association of menstrual and reproductive factors with breast cancer risk and the influence of these factors on the temporal trend of breast cancer incidence, we analyzed data from the Shanghai Breast Cancer Study, a population-based case-control study of breast cancer recently completed among Chinese women in urban Shanghai. In-person interviews were completed for 1,459 women newly diagnosed with breast cancer between ages 25 and 64 and for 1,556 controls frequency-matched to cases by age. Unconditional logistic regression was employed to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) related to menstrual and reproductive factors. Earlier menarcheal age, nulliparity, and later age at first live birth were associated with increased risk of breast cancer among both pre- and post-menopausal women, while never having breast-fed and later age at menopause were associated with elevated risk only among post-menopausal women. Among controls, 32% of younger women (</=40 years) and 24% of older women (>40 years) reported starting menarche at age of 13 or younger, and this factor contributed to 44% of cases diagnosed among younger women and 26% to 28% of cases in older women. Older age at first live birth or at menopause explained a considerable portion of cases diagnosed in older, but not younger, women. Our study suggests that the changes in menstrual and reproductive patterns among women in Shanghai have contributed to the recent increase in breast cancer incidence, particularly among younger women.

Adult↗
PubMed2000

Unrelated donor marrow transplantation for chronic myelogenous leukemia: 9 years' experience of the national marrow donor program.

Over a period of 8.5 years (February 1988 to October 1996), 1423 patients with chronic myelogenous leukemia (CML) underwent unrelated donor (URD) bone marrow transplants (BMTs) facilitated by the National Marrow Donor Program (NMDP) at 85 transplant centers. One hundred thirty-seven evaluable (9.9%) patients failed to engraft, and an additional 83 (6.6%) evaluable patients experienced late graft failure. Grade III/IV acute graft-versus-host disease (GVHD) developed in 33% of patients (95% confidence interval [CI], 30%-36%). The incidence of extensive chronic GVHD was 60% (95% CI, 56%-63%) at 2 years. Only 5.7% of patients (95% CI, 3.6%-7.8%) transplanted in chronic phase developed hematologic relapse at 3 years. Several factors were independently associated with improved disease-free survival (DFS), including transplant in chronic phase, transplant within 1 year of diagnosis, younger recipient age, a cytomegalovirus seronegative recipient, and development of no or mild acute GVHD. The combined effect of these factors on outcome is manifest in a subset (n = 157) of young (less than 35 years), chronic phase patients transplanted within 1 year of diagnosis using HLA-matched donors who had 63% (95% CI, 53%-73%) DFS at 3 years. URD BMT therapy for CML is both feasible and effective with more frequent and more rapid identification of suitable donors. Early URD transplant during chronic phase yields good results and should be considered in CML patients otherwise eligible for transplant but without a suitable related donor.

Age Factors↗
PubMed2000

Dual voxel proton magnetic resonance spectroscopy in the healthy elderly: subcortical-frontal axonal N-acetylaspartate levels are correlated with fluid cognitive abilities independent of structural brain changes.

The published literature suggests that degeneration of the subcorticofrontal networks may underlie cognitive ageing, but appropriate methods to examine this in vivo have been lacking. Proton Magnetic Resonance Spectroscopy ((1)H-MRS) has now been used in a number of clinical studies to assess cerebral pathophysicochemistry and recently has been utilized to examine the relationship between neurochemical markers and cognitive functioning in normal individuals. Results have been somewhat conflicting and difficult to interpret. To further clarify the role of the cognitive spectroscopy technique, we measured N-acetylaspartate (NAA) levels in the frontal subcortical white matter and the occipitoparietal grey matter and correlated them with performance in different cognitive domains in a group of twenty healthy elderly individuals. Subjects underwent whole brain T(1)- and T(2)-weighted magnetic resonance imaging (MRI), dual voxel short echo-time (1)H-MRS, and a comprehensive neuropsychological assessment. Individual tests of executive and attentional abilities, and a principal components composite score reflecting these skills, but not measures of memory or verbal abilities, were correlated with NAA concentration in the frontal white matter only. These relationships were independent of other neurocognitive predictors of executive impairment such as age, midventricular dilation, frontal white matter disease, and presenescent verbal proficiency. This study suggests the ability of (1)H-MRS to differentiate anatomically distinct neurochemical markers related to specific cognitive abilities. In particular, neurometabolic fitness of the frontal subcortical-cortical axonal fibers may be important in mediating fluid intellectual processing. Longitudinal MRS studies are required to determine if the present results reflect different rates of neurocellular degeneration or preexisting individual differences in neuronal density.

Aged↗
PubMed2000

Allergic disorders and the risk of childhood acute lymphoblastic leukemia (United States).

OBJECTIVES: To test the hypothesis that childhood acute lymphoblastic leukemia (ALL) is associated with allergic disorders. METHODS: We compared the histories of selected allergic disorders (asthma, hay fever, food or drug allergies, eczema, and hives) of 1842 cases of ALL with those of 1986 individually matched controls. The histories of the allergic disorders among siblings of cases and controls were also compared. RESULTS: The combined history of any one or more of the five allergic disorders evaluated was associated with a significant reduced risk of ALL (adjusted OR = 0.7, 95% CI 0.6-0.8), as were histories of four specific allergic disorders (asthma, hay fever, food or drug allergies, and eczema). The combined history of any one or more of the five allergic disorders among any of the siblings of the study subjects also revealed a significantly inverse association (adjusted OR = 0.9, 95% CI 0.8-1.0). CONCLUSION: The results from this study, in agreement with most previous studies on adult cancer, suggest that allergic disorders may be associated with a reduced risk of childhood ALL.

Adult↗
PubMed2000

Patterns of infection and day care utilization and risk of childhood acute lymphoblastic leukaemia.

To investigate if decreased exposure to common childhood infections is associated with risk of childhood acute lymphoblastic leukaemia (ALL) we conducted a case-control study of 1842 newly diagnosed and immunophenotypically defined cases of ALL under age 15, and 1986 matched controls in the US. Data regarding day care, sibship size and common childhood infections were obtained through parental interviews. Data were analysed stratified by leukaemia lineage and separately for 'common' childhood ALL (age 2-5 years, CD19, CD10-positive). Neither attendance at day care nor time at day care was associated with risk of ALL overall or 'common' ALL. Ear infections during infancy were less common among cases, with odds ratios of 0.86, 0.83, 0.71 and 0.69 for 1, 2-4, 5+ episodes, and continuous infections respectively (trend P = 0.026). No effect of sibship size or birth interval was seen. With one exception (ear infections), these data do not support the hypothesis that a decrease in the occurrence of common childhood infection increases risk of ALL.

Adolescent↗
PubMed1999

Reliability and validity of ratings of signal hyperintensities on MRI by visual inspection and computerised measurement.

Brain magnetic resonance imaging (MRI) scans on 98 elderly subjects, 62 with a diagnosis of schizophrenia and 36 healthy controls, were independently and blindly rated by two investigators using the visual rating methods of Fazekas et al. (Fazekas, F., Chawluk, J.B., Alavi, A., Hurtig, H.I., Zimmerman, R.A., 1987. MR signal abnormalities at 1.5 T in Alzheimer's dementia and normal aging. American Journal of Neuroradiology 8, 421-426) and Victoroff et al. (Victoroff, J., Mack, W.J., Grafton, S.T., Schreiber, S.S., Chui, H.C., 1994. A method to improve interrater reliability of visual inspection of brain MRI scans in dementia. Neurology 44, 2267-2276) for periventricular, deep white matter and subcortical gray matter signal hyperintensities (SHs) on T2-weighted images. The hyperintense signal volumes were measured by manual delineation of the signals on a workstation using Analyze software (computerised method). The subjects also underwent a detailed neuropsychological assessment. There was a high correlation between two experienced raters for both visual ratings, and the correspondence between the two methods was high. The inter-rater reliability for the computerised method was modest but significant, and the association between the visual and computerised methods was good except for ratings for SHs in subcortical nuclei. The Fazekas and computerised methods, and to a lesser degree the Victoroff method, had modest but significant correlations with some neuropsychological test measures. In conclusion, we did not demonstrate a clear superiority in reliability or validity for one demanding computerised method of rating SHs. Visual ratings should therefore be considered adequate for most clinical and research purposes, but such ratings should be accompanied by adequate training and the provision of standard reference images.

Aged↗
PubMed1999

The generation of endostatin is mediated by elastase.

Endostatin, a potent inhibitor of angiogenesis and tumor growth, is a COOH-terminal fragment of collagen XVIII derived through cleavage of an Ala-His linkage by an as yet unidentified endostatin-processing enzyme. Endostatin was originally isolated from the conditioned medium of hemangioendothelioma (EOMA) cells. By investigating the processing of collagen XVIII to endostatin by EOMA cells, we show here that the generation of endostatin can be mediated by an elastase activity. We also show that several members of the elastase family can act as an endostatin-processing enzyme by specifically cleaving the Ala-His linkage and releasing endostatin from a precursor molecule. We further suggest that the generation of endostatin from collagen XVIII is at least a two-step process, involving a metal-dependent early step and an elastase activity-dependent final step.

Collagen↗
PubMed1999

Aggregation kinetics and stability of structures formed by magnetic microspheres.

Stable rings formed by magnetization-controllable microspheres at zero field are observed and reported in this Rapid Communication. The magnetic microspheres were made by plating glass beads with a critical thickness of Ni film. We found that the ring leading to magnetic flux closure is the most stable configuration. At high concentrations, all individual rings, chains, and clusters join together to form a netlike structure. A computer simulation based on the dipole-dipole interaction, without thermal noise, has been carried out, and the results are in good agreement with the experimental observations. Based on an analytic approach we give a simple explanation of the formation and stability of rings.

Journal Article↗
PubMed1999

[Repair of recurrent laryngeal nerve injuries after thyroidectomy].

OBJECTIVE: In order to investigate the opportunity of repair and prognosis of recurrent laryngeal nerve injuries after thyroidectomy. METHODS: Twelve cases with recurrent laryngeal nerve injuries after thyroidectomy were immediately and delayed operated on nerve repair and reinnervation. In immediate operation, 5 cases were repaired by direct recurrent laryngeal nerve suture, and 1 case was treated by transposition of the phrenic nerve to the recurrent laryngeal nerve and sutured the adductor branch to the branch of ansa cervicalis. In delayed operation, 3 cases were treated by anastomosis the main trunk of ansa cervicalis to the adductor branch of recurrent laryngeal nerve, and 3 cases were operated on neuromuscular pedicle to reinnervate posterior cricoarytenoid muscle. RESULTS: Followed up 6 months, the effect was excellent in 1 case who was immediately operated by selective reinnervation of the abductor and adductor muscles of the larynx, better in 9 cases, and poor in 2 cases who were delayed operated over 12 months. CONCLUSION: It can be concluded that the earlier reinnervation is performed, the better prognosis is.

Adult↗
PubMed1999

[Studies on the continuous culture and the growth of Entamoeba gingivalis].

AIM: To establish a method for continuous culture of Entamoeba gingivalis(E. g.). METHODS: The culture conditions of E. g. were compared by observing its size and survival time at room temperature. RESULTS: The growth of E. g. under different culture conditions including culture medium, temperature and pH were compared. The accompanying bacteria associate with E. g. FJ4 were isolated and identified. The average size of E. g. was 13.19 microns-49.93 microns x 9.88 microns-30.74 microns. The optimal culture conditions of E. g. were: modified LES or YES medium, pH 6.4-6.7, nutritional liquids such as Locke's solution or yolk liquid with 20% bovine serum, penicillin, streptomycin and rice flour at 35 degrees C. Reproduction of E. g. peaked at the fourth day of incubation, and the survival time of E. g. was 120 h-168 h. CONCLUSION: E. g. could be continuously cultured in modified LES or YES medium by inoculating once every four days.

Animals↗
PubMed1999

[Clinical significance and changes of fibrillation potential amplitude following denervation of laryngeal muscles].

OBJECTIVE: To evaluate the value of clinical application of examination of fibrillation potential amplitude of laryngeal electromyogram. METHOD: Fifty-four patients (65 sides) with recurrent laryngeal nerve paralysis were examined and only the maximum fibrillation potential amplitudes were recorded in the posterior cricoarytenoid muscles and thyroarytenoid muscles. RESULT: There was no significant difference between sexes, ages and sides. The fibrillation potential amplitude was maximum at 3 to 4 months after denervation of the posterior cricoarytenoid muscle or at 5 to 6 months after denervation of the thyroarytenoid muscle and still remained at certain level for years in some patients. Significant difference was showed in complete and incomplete nerve injuries groups, but changes of amplitude with time in incomplete nerve injuries group were small. CONCLUSION: The changes of fibrillation potential amplitude might indicate that the changes from muscle denervation was still reversible and might be more accurate than traditional method of examination.

Adult↗