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Biomedical subjects

F Yu

Publications and source records attributed to F Yu.

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

[Clinical analysis of 1,827 patients with reflux esophagitis].

OBJECTIVE: To investigate clinical and endoscopic characteristics of reflux esophagitis (RE) in Chinese. METHODS: 1 827 patients with RE, diagnosed by endoscopy in the past 10 years, were divided into different grades according to Los Angeles System and Chinese Standard. A part of them underwent esophageal manometry, 24-hour pH monitoring, and 24-hour bilirubin monitoring. The relationship between age, sex, symptom, accompanied diseases and each examinations were analyzed. RESULTS: RE was 2.02% of the total endoscopy number, and male vs female was 3.9:1, mean age was (52.02 +/- 14.38) years old. Only 36.29% of RE patients have typical reflux symptom. Patients with light mordent (Los Angeles System A, B and Chinese Standard I) RE were more than those with severe RE. Both of the time of esophageal acid exposure and total percent time bilirubin absorbance >or=0.14 for RE was significantly more than normal (P < 0.01). CONCLUSION: The incidence of RE in Chinese is lower than that in Western and the severity is less. Most of RE are male and aged. There is a close association between RE and both of gastroesophageal reflux and duodenogastroesophageal reflux. Endoscopy is very important for diagnosis of RE.

Adolescent↗
PubMed2001

[Intracellular potential changes in crucian carps Mauthner cells evoked by vagal sensory inputs].

In the present experiments, microelectrode recording technique was used to explore the electrophysiological properties of Mauthner cells (M-cells) with stimuli applied to the right vagus. Direct stimulation of the right vagus evoked short-latency, long-lasting, graded, and complex postsynaptic potentials (PSPs) on both Mauthner cell bodies in crucian carp, which are stimulus strength- and frequency- dependent. The evoked PSPs reduced the amplitudes of the antidromic action potentials. After intramuscular injection of strychnine, both amplitude and averaged duration of the PSPs increased, on which two or more action potentials were superimposed. The results suggest that the afferent pathways from vagus to M-cells are mediated by several neuron chains with different numbers of relayed synapses, and they may be excitatory and/or inhibitory in nature. Therefore vagus input would modulate the excitability of the M-cells.

Action Potentials↗
PubMed2000

Survey of genetic alterations in gastrinomas.

Gastrinomas are rare gastrin-secreting endocrine tumors that usually arise in the duodenum or pancreas and, if untreated, can cause severe peptic ulcers or metastatic disease. Although most tumors are sporadic they are especially common in patients with multiple endocrine neoplasia type 1 (MEN1), and most studies of these tumors have focused on the role of the MEN1 gene. Although the gene is commonly altered in sporadic tumors, this finding is not universal, and it is highly likely that other genetic defects play a significant role. In the present study, an in-depth analysis of the DNA of eight tumors was carried out in an effort to localize these areas. The experiments consisted of an analysis of 400 microsatellite marker loci distributed evenly throughout the human genome, and the results were confirmed with comparative genomic hybridization. Whereas deletions encompassing the MEN1 gene were seen in two tumors, the most striking result was multiple large rearrangements on chromosome 1 in two of the tumors with hepatic metastases. In several instances, an individual tumor had abnormalities of every informative maker on a given chromosome, presumably as a result of aneuploidy affecting that chromosome. Such defects were only seen in the four large or aggressive tumors, and the total number of chromosomes affected in a tumor ranged from 1 to a high of 13 in a patient who had an unusually aggressive tumor This tumor also showed microsatellite instability, and this is the first report of such a defect in gastrinomas. This study implicates chromosome 1 defects, aneuploidy, and perhaps mismatch repair defects as importan features of gastrinomas; deletions involving the MEN1 gene were con firmed, but the rest of the genome was free of large deletions or amplifications.

Allelic Imbalance↗
PubMed2000

PCD1, a novel gene containing PDZ and LIM domains, is overexpressed in several human cancers.

In an effort to discover novel genes differentially expressed in human pancreatic cancer, we have identified a gene named PCD1 (pancreatic cancer derived) that is up-regulated in pancreatic dysplasia and cancer relative to normal pancreatic ductal epithelium. We cloned the full length (4572 bp) of this gene, which encodes a novel protein of 1064 amino acids containing a PDZ domain and a LIM domain. An alternatively spliced form with a deletion of 30 bp in the coding region was also found. In situ hybridization results showed that PCD1 is highly expressed in a significant percentage of colon, breast, liver, lung, pancreas, stomach, and prostate tumor tissues but is expressed in very few normal tissues. Northern blot hybridization confirmed the overexpression of PCD1 in colon and breast tumor tissues and also showed strong expression of PCD1 in the heart as well as in HeLa cells. Real-time quantitative reverse transcription-PCR verified the overexpression of PCD1 in primary colon tumors or in liver metastases relative to normal colon tissues in five of eight patients. The PCD1 gene maps to human chromosome 13q21.33. Because of its high levels of expression in neoplastic tissues and the presence of both PDZ and LIM domains, we suggest that PCD1 may play an important role in cytoskeletal reorganization during carcinogenesis.

Amino Acid Sequence↗
PubMed2000

Histone deacetylase-independent transcriptional repression by methyl-CpG-binding protein 2.

Methyl-CpG-binding protein 2 (MeCP2) contains a transcriptional repression domain (TRD), which can act by recruitment of a large transcriptional co-repressor complex containing histone deacetylases HDAC1 and 2. We demonstrate here that transient transcription from the SV40 enhancer/promoter or the SV40 promoter is strongly repressed in a histone deacetylase-independent manner, since repression is not alleviated by Trichostatin A (TSA). In a mutational analysis, repression depends on a conserved 30 residue sequence containing two clusters of basic amino acids. Mutation of the first of these clusters inhibits in vitro interaction between TRD and mSin3A. Furthermore, a subdomain of the TRD containing the conserved 30-residue sequence and 16 flanking amino acids was sufficient to compromise VP16-activated transcription. In summary, our results indicate an alternative, histone deacetylase-independent pathway of transcriptional repression by MeCP2.

3T3 Cells↗
PubMed2000

Analysis of partner of inscuteable, a novel player of Drosophila asymmetric divisions, reveals two distinct steps in inscuteable apical localization.

Asymmetric localization is a prerequisite for inscuteable (insc) to function in coordinating and mediating asymmetric cell divisions in Drosophila. We show here that Partner of Inscuteable (Pins), a new component of asymmetric divisions, is required for Inscuteable to asymmetrically localize. In the absence of pins, Inscuteable becomes cytoplasmic and asymmetric divisions of neuroblasts and mitotic domain 9 cells show defects reminiscent of insc mutants. Pins colocalizes with Insc and interacts with the region necessary and sufficient for directing its asymmetric localization. Analyses of pins function in neuroblasts reveal two distinct steps for Insc apical cortical localization: A pins-independent, bazooka-dependent initiation step during delamination (interphase) and a later maintenance step during which Baz, Pins, and Insc localization are interdependent.

Amino Acid Sequence↗
PubMed2000

Surgical undertreatment of glaucoma in black beneficiaries of medicare.

OBJECTIVE: To identify whether there was surgical undertreatment of glaucoma in black beneficiaries of Medicare from 1991 to 1994. METHODS: We performed a retrospective cohort analysis on all argon laser trabeculoplasty or trabeculectomy surgery claims to the Health Care Financing Administration between 1991 and 1994. There were 191 287 Medicare patients who were black or white, at least 65 years of age, and resided in the United States at the time of their glaucoma surgery. Age- and sex-adjusted rates were obtained and compared with surgery rates expected based on disease prevalence. RESULTS: The age-sex-adjusted rate ratio of glaucoma surgical procedures for blacks to whites was 2.14. Assuming that treatments should be done in proportion to age-race prevalence, blacks undergo glaucoma surgery at approximately 47% below the expected rate. CONCLUSIONS: Blacks underwent argon laser trabeculoplasties and trabeculectomies at half the rate of whites from 1991 to 1994. Although in 1993 and 1994 there was a slight trend toward higher surgery rates in blacks, the magnitude of this improvement was small compared with estimated differences in the surgery rates between blacks and whites.

Black or African American↗
PubMed2000

Tropospheric sulfate aerosol formation via ion-ion recombination.

We propose a source of aerosols in the lower atmosphere associated with the creation, growth, and recombination of ubiquitous cosmogenically generated ions. This particle source should be favorable in the relatively clean, stable marine boundary layer, providing a uniform, continuous fine particle generator in the presence of dimethylsulfide emissions. Through this mechanism, new sulfate aerosols can be formed at sulfuric acid vapor partial pressures well below the supersaturations required for homogeneous binary nucleation of sulfuric acid/water solutions, which is consistent with numerous observations of new particle formation under sub-saturated conditions. The evolving aerosols in turn control the acid vapor concentration and thus modulate the sizes of the precursor ions and the rate of new particle formation. A simple model representing this nonlinear coupled system predicts that the physical and chemical processes connecting ions, vapors, and aerosols effectively constrain the particle population to a relatively narrow range of values. This self-limiting behavior may explain in part the apparent stability of the marine sulfate aerosol, with mean concentrations of the order of several hundred per cubic centimeter.

Aerosols↗
PubMed2000

Galectin-3 mediates genistein-induced G(2)/M arrest and inhibits apoptosis.

Many recent studies have focused on potential chemopreventive activities of dietary genistein, a natural isoflavonoid compound found in soy products. Genistein has been implicated in anticancer activities, including differentiation, apoptosis, inhibition of cell growth and inhibition of angiogenesis. In previous studies, genistein was shown to induce apoptosis and cell cycle arrest at G(2)/M in several cancer cell lines in vitro, which is associated with induction of p21(WAF1/CIP1), a universal inhibitor of cyclin-dependent kinases. At present, the molecular basis for diverse genistein-mediated cellular responses is largely unknown. In the present study, we investigated whether galectin-3, an anti-apoptotic gene product, regulates genistein-mediated cellular responses. We show that genistein effectively induces apoptosis without detectable cell cycle arrest in BT549, a human breast epithelial cell line which does not express galectin-3 at a detectable level. In galectin-3 transfected BT549 cells, genistein induced cell cycle arrest at the G(2)/M phase without apoptosis induction. Interestingly, genistein induces p21(WAF1/CIP1) expression in galectin-3-expressing BT549 cells, but not in control BT549 cells undergoing apoptosis. Collectively, the results of the present study suggest that galectin-3, at least in part, is a critical determinant for genistein-mediated cell cycle arrest and apoptosis, and genistein induction of p21(WAF1/CIP1) is associated with cell cycle arrest, but not required for apoptosis induction.

Anticarcinogenic Agents↗
PubMed2000

Parkinson's disease mortality and pesticide exposure in California 1984-1994.

BACKGROUND: In the last two decades reports from different countries emerged associating pesticide and herbicide use with Parkinson's disease (PD). California growers use approximately 250 million pounds of pesticides annually, about a quarter of all pesticides used in the US. METHODS: We employed a proportional odds mortality design to compare all cases of PD recorded as underlying (1984-1994) or associated causes (1984-1993) of death occurring in California with all deaths from ischaemic heart disease (ICD-9 410-414) during the same period. Based on pesticide use report data we classified California counties into several pesticide use categories. Agricultural census data allowed us to create measures of percentage of land per county treated with pesticides. Employing logistic regression models we estimated the effect of pesticide use controlling for age, gender, race, birthplace, year of deaths, and education. RESULTS: Mortality from PD as the underlying cause of death was higher in agricultural pesticide-use counties than in non-use counties. A dose response was observed for insecticide use per county land treated when using 1982 agricultural census data, but not for amounts of restricted pesticides used or length of residency in a country prior to death. CONCLUSIONS: Our data show an increased PD mortality in California counties using agricultural pesticides. Unless all of our measures of county pesticide use are surrogates for other risk factors more prevalent in pesticide use counties, it seems important to target this prevalent exposure in rural California in future studies that use improved case finding mechanisms and collect pesticide exposure data for individuals.

Aged↗
PubMed2000

Effect of air pollution on preterm birth among children born in Southern California between 1989 and 1993.

We evaluated the effect of air pollution exposure during pregnancy on the occurrence of preterm birth in a cohort of 97,518 neonates born in Southern California. We used measurements of carbon monoxide (CO), nitrogen dioxide, ozone, and particulate matter less than 10 microm (PM10) collected at 17 air-quality-monitoring stations to create average exposure estimates for periods of pregnancy. We calculated crude and adjusted risk ratios (RRs) for premature birth by period-specific ambient pollution levels. We observed a 20% increase in preterm birth per 50-microg increase in ambient PM10 levels averaged over 6 weeks before birth [RRcrude = 1.20; 95% confidence interval (CI) = 1.09-1.33] and a 16% increase when averaging over the first month of pregnancy (RRcrude = 1.16; 95% CI = 1.06-1.26). PM10 effects showed no regional pattern. CO exposure 6 weeks before birth consistently exhibited an effect only for the inland regions (RRcrude = 1.13; 95% CI = 1.08-1.18 per 3 parts per million), and during the first month of pregnancy, the effect was weak for all stations (RRcrude = 1.04; 95% CI = 1.01-1.09 per 3 parts per million). Exposure to increased levels of ambient PM10 and possibly CO during pregnancy may contribute to the occurrence of preterm births in Southern California.

Air Pollutants↗
PubMed2000

Mink cell focus-forming murine leukemia virus infection induces apoptosis of thymic lymphocytes.

In a previous study we identified the subpopulations of thymus cells that were infected by the lymphomagenic MCF13 murine leukemia virus (MLV) (F. K. Yoshimura, T. Wang, and M. Cankovic, J. Virol. 73:4890-4898, 1999) and observed an effect on thymus size by virus infection. In this report we describe our results which demonstrate that MCF13 MLV infection of thymuses reduced the number of T lymphocytes in this organ. Histological examination showed diffuse lymphocyte depletion, which was most striking in the CD4(+) CD8(+) lymphocyte-enriched cortical zone. Consistent with this, flow cytometric analysis showed that the lymphocytes which were depleted were predominantly the immature CD3(-) CD4(+) CD8(+) and CD3(+) CD4(+) CD8(+) cells. A comparison of the percentages of live, apoptotic, and dead cells of the gp70(+) and gp70(-) thymic lymphocytes suggested that this effect on thymus cellularity is a result of virus infection. Studies of the survival of thymic T lymphocytes in culture showed that cells from MCF13 MLV-inoculated mice underwent greater apoptosis and death than cells from control animals. Assays for apoptosis included 7-amino-actinomycin D staining, DNA fragmentation, and cleavage of caspase-3 and poly(ADP-ribose) polymerase proenzymes. Our results suggest that apoptosis of thymic lymphocytes by virus infection is an important step in the early stages of MCF13 MLV tumorigenesis.

Animals↗
PubMed2000

Effects of thyroid hormone receptor gene disruption on myosin isoform expression in mouse skeletal muscles.

Skeletal muscle is known to be a target for the active metabolite of thyroid hormone, i.e., 3,5,3'-triiodothyronine (T(3)). T(3) acts by repressing or activating genes coding for different myosin heavy chain (MHC) isoforms via T(3) receptors (TRs). The diverse function of T(3) is presumed to be mediated by TR-alpha(1) and TR-beta, but the function of specific TRs in regulating MHC isoform expression has remained undefined. In this study, TR-deficient mice were used to expand our knowledge of the mechanisms by which T(3) regulates the expression of specific MHC isoforms via distinct TRs. In fast-twitch extensor digitorum longus (EDL) muscle, TR-alpha(1)-, TR-beta-, or TR-alpha(1)beta-deficient mice showed a small but statistically significant decrease (P < 0.05) of type IIB MHC content and an increased number of type I fibers. In the slow-twitch soleus, the beta/slow MHC (type I) isoform was significantly (P < 0. 001) upregulated in the TR-deficient mice, but this effect was highly dependent on the type of receptor deleted. The lack of TR-beta had no significant effect on the expression of MHC isoforms. An increase (P < 0.05) of type I MHC was observed in the TR-alpha(1)-deficient muscle. A dramatic overexpression (P < 0.001) of the slow type I MHC and a corresponding downregulation of the fast type IIA MHC (P < 0.001) was observed in TR-alpha(1)beta-deficient mice. The muscle- and fiber-specific differences in MHC isoform expression in the TR-alpha(1)beta-deficient mice resembled the MHC isoform transitions reported in hypothyroid animals, i.e., a mild MHC transition in the EDL, a dramatic but not complete upregulation of the beta/slow MHC isoform in the soleus, and a variable response to TR deficiency in different soleus muscle fibers. Thus the consequences on muscle are similar in the absence of thyroid hormone or absence of thyroid hormone receptors, indicating that TR-alpha(1) and TR-beta together mediate the known actions of T(3). However, it remains unknown how thyroid hormone exerts muscle- and muscle fiber-specific effects in its action. Finally, although developmental MHC transitions were not studied specifically in this study, the absence of embryonic and fetal MHC isoforms in the TR-deficient mice indicates that ultimately the transition to the adult MHC isoforms is not solely mediated by TRs.

Adenosine Triphosphatases↗
PubMed2000

Subclinical infection with the nematode Trichostrongylus colubriformis increases gastrointestinal tract leucine metabolism and reduces availability of leucine for other tissues.

Gastrointestinal (GI) tract leucine metabolism was measured in 6- to 9-mo-old lambs subjected to trickle infection with Trichostrongylus colubriformis larvae and in separate animals that were not infected. Animals prepared with a jejunal catheter and with indwelling catheters into the aorta and the portal- (PDV) and mesenteric- (MDV) drained viscera were infused simultaneously with [1-13C] and [5,5,5-2H3] leucine to determine GI tract sequestration of leucine from arterial and luminal amino acid pools by tracer and tracee arteriovenous concentration differences. Leucine oxidative losses and net fluxes were also determined across the GI tract. Infection had no detectable effect on whole-body leucine flux, but it increased total GI tract leucine sequestration by 24% (P<.05) and GI tract oxidative losses of leucine by 22 to 41% (P<.01). Net PDV fluxes of leucine were decreased by 20 to 32% during the infection. The infection did not alter either the proportion of precursor leucine used by GI tract metabolism that was derived from the arterial leucine pool (.84 to .88) or the proportional sequestration of digesta-derived leucine during "first pass" absorptive metabolism (.12 to .18). These findings help to elucidate the metabolic basis for the reduced growth rates and nitrogen retention observed when animals are subjected to subclinical nematode infection.

Animals↗
PubMed2000

Immobilization of antibodies on ultraflat polystyrene surfaces.

BACKGROUND: Functional antibody surfaces were prepared on ultraflat polystyrene surfaces by physical adsorption, and the uniform distribution of monoclonal antibodies against hepatitis B surface antigen (anti-HBs) on such surfaces and the presence of dense hepatitis B surface antigen (HBsAg) particles captured by immobilized antibodies were identified. METHODS: A model polystyrene film was spin-coated directly onto a silicon wafer surface. Atomic force microscopy was used to directly monitor the immobilization of anti-HBs antibodies and their specific molecular interaction with HBsAg. Enzyme immunoassay was also used to characterize functional antibody surfaces. RESULTS: A mean roughness of 2 A for areas of 25 microm(2) was produced. We found a uniform distribution of anti-HBs antibodies on ultraflat polystyrene surfaces and the presence of dense HBsAg particles bound to such anti-HBs surfaces after incubation with HBsAg. CONCLUSIONS: This study confirmed the potential of preparing dense, homogeneous, highly specific, and highly stable antibody surfaces by immobilizing antibodies on polystyrene surfaces with controlled roughness. It is expected that such biofunctional surfaces could be of interest for the development of new solid-phase immunoassay techniques and biosensor techniques.

Adsorption↗
PubMed2000

[Detection of microbes adherent to particles in a closed environment].

OBJECTIVE: In order to provide reference for controlling and monitoring the environmental contamination in the spacecraft, the species and amount of microbes, which adhere to the suspended particles with different size in a closed environment were detected. METHOD: According to USA EPA IP-10, particles were continuously sampled by an impactor in a closed environment. The particles were divided into three grades by their aerodynamic diameters (AD): 100 micrometers > or = AD > 10 micrometers, 10 micrometers > or = AD>2 micrometers and AD < or = 2 micrometers. Clean outdoor air was collected as control by the same way. The collected particles were precisely weighed. The microbes that adhere to the particles were cultivated, counted and identified. RESULT: By calculating total suspended particles (TSP) and inhalant particles (IP) of the closed environment, counting, clarifying and identifying the microbes, 6 kinds of bacteria, 2 genus of actinomyces and 6 kinds of fungi that adhere to the particles were detected. CONCLUSION: The particles in a closed environment may have some effect on human health and instruments.

Actinomyces↗
PubMed2000

[Long-term results of combined therapy for primary osteosarcoma in extremities].

OBJECTIVE: To evaluate the survival rates, functional outcome, and complications between the combined and non-combined treatment of primary osteosarcoma of the extremities. METHOD: From 1977 through 1992, 170 patients with high-graded, nonmetastatic osteosarcoma were treated. Their average age at diagnosis was 21 years old (ranging from 6 to 52). Tumors were observed at distal femurs in 80 patients (47%), proximal tibia in 51 (30%), proximal humors in 10 and other locations in 22. Combined therapy (en bloc resection of tumor with preoperative and postoperative neoadjuvant chemotherapy) was given 104 patients and non-combined therapy (tumor resection only) to 66. Ninety-four patients underwent limb salvage surgery. In 76 patients who received amputations or disarticulations 33 received chemotherapy. RESULTS: The 5-and 10-year-survival rates were 61% and 53% in the combined therapy group and 28% and 26% in the non-combined therapy group. Local recurrence rate was 23% in limb salvage surgery group and 5.2% in amputation group. Functional evaluation of 80 patients showed that the patients who underwent salvage surgery had higher functional scores than those who had an amputation according to MSTS scoring system (1993). The average scores reached 71% in the salvage surgery group and 53% in the amputation group. CONCLUSIONS: In this study, long-term that combined therapy raised the survival rate of the patients with osteosarcoma. The ase of en bloc resection of bone tumor and reconstructive technique, has enable limb salvage procedures possible to produce excellent functional outcomes. The patients who well have responses to preoperative chemotherapy may have a higher survival rate.

Adolescent↗