Biomedical subjects

H Yu

Publications and source records attributed to H Yu.

At least 217 records · Page 12Linked to original sources

PubMed2000

Patient compliance is critical for equivalent clinical outcomes for breast cancer treated by breast-conservation therapy.

OBJECTIVE: To determine the compliance with a standard breast-conservation therapy (BCT) program in a predominantly indigent, minority population of patients with early breast cancer (stage I and II) served by a rural state institution in the South; to compare the clinical outcomes of this group with those reported in clinical trials; and to examine the socioeconomic factors that may have contributed to the rate of compliance. SUMMARY BACKGROUND DATA: Disease-free survival and overall survival in early breast cancer treated by BCT versus modified radical mastectomy are reported to be equivalent in prospective randomized trials. However, patients enrolled in clinical trials may not be representative of patients living in the various diverse communities that make up the United States. The authors' hypothesis is that patients enrolled in clinical trials at the national level may not be representative of indigent patients in the rural South and that clinical trial results may not be directly applicable. METHODS: A retrospective review of 55 women with early-stage breast cancer treated from 1990 to 1995 was performed. Clinical data, compliance with treatment and clinical follow-up, and recurrence rates were examined. Statistical analysis performed include the Fisher exact test, Kaplan-Meier survival analysis, and log-rank test. RESULTS: Full compliance (defined as completion of the entire course of radiation therapy and clinical follow-up) with the BCT program was observed in only 36% of patients. Fifteen of the 35 noncompliant patients did not complete radiation therapy. A significantly higher local failure rate was observed: 8 of these 15 patients (53%) have had local failure. In contrast, patients who were either in full compliance with the BCT program or were deficient only in that they missed part of their clinical follow-up had local failure rates of 5% (1/20) and 10% (2/20), respectively. Age, race, stage of cancer, economic status (measured by availability of medical insurance), distance of patient's residence from the hospital, and education level were evaluated as potential predictors of compliance. None predicted patient compliance, although a trend toward higher compliance was noted in patients with a higher education level, as determined by literacy testing. CONCLUSIONS: Compliance with the BCT protocol at the authors' institution was worse than reported in clinical trials, and noncompliance translated into a significant increase in the local failure rate. Factors examined suggest that literacy may play a role in predicting compliance. Although BCT should be discussed with all breast cancer patients, the judicious application of clinical trial data to an institution's local population is warranted.

Breast Neoplasms↗

PubMed2000

Computer-based radiation safety training for hospital radiation workers.

Conducting a hospital-based radiation safety training class may lead to temporary technologist staffing shortages resulting in a reduction of patient services or even the cessation of all routine patient services. Use of an interactive computer-based radiation safety training software program may provide a practical alternative for hospital diagnostic and therapeutic radiation departments, as well as other hospital departments utilizing radiation sources, in meeting annual radiation safety training requirements for radiation workers. Medical radiation workers' participation in computer-based radiation safety training can make a positive impact on radiation safety awareness in the hospital, assist license holders in satisfying regulatory training requirements, ensure maximum participation of staff technologists, and reduce the burden of technologist staffing shortages caused by traditional methods of training.

Computer-Assisted Instruction↗

PubMed2000

Lattice boltzmann method for compressible flows with high mach numbers

In this paper we present a lattice Boltzmann model to simulate compressible flows by introducing an attractive force. This scheme has two main advantages: one is to soften sound speed effectively, which greatly raises the Mach number (up to 5); another is its relative simple procedure. Simulations of the March cone and the comparison between theoretical expectations and simulations demonstrate that the scheme is effective in the simulation of compressible flows with high Mach numbers, which would create many new applications.

Journal Article↗

PubMed2000

Identification and characterization of three orchid MADS-box genes of the AP1/AGL9 subfamily during floral transition.

Gene expressions associated with in vitro floral transition in an orchid hybrid (Dendrobium grex Madame Thong-In) were investigated by differential display. One clone, orchid transitional growth related gene 7 (otg7), encoding a new MADS-box gene, was identified to be specifically expressed in the transitional shoot apical meristem (TSAM). Using this clone as a probe, three orchid MADS-box genes, DOMADS1, DOMADS2, and DOMADS3, were subsequently isolated from the TSAM cDNA library. Phylogenetic analyses show that DOMADS1 and DOMADS2 are new members of the AGL2 subfamily and SQUA subfamily, respectively. DOMADS3 contains the signature amino acids as with the members in the independent OSMADS1 subfamily separated from the AGL2 subfamily. All three of the DOMADS genes were expressed in the TSAM during floral transition and later in mature flowers. DOMADS1 RNA was uniformly expressed in both of the inflorescence meristem and the floral primordium and later localized in all of the floral organs. DOMADS2 showed a novel expression pattern that has not been previously characterized for any other MADS-box genes. DOMADS2 transcript was expressed early in the 6-week-old vegetative shoot apical meristem in which the obvious morphological change to floral development had yet to occur. It was expressed throughout the process of floral transition and later in the columns of mature flowers. The onset of DOMADS3 transcription was in the early TSAM at the stage before the differentiation of the first flower primordium. Later, DOMADS3 transcript was only detectable in the pedicel tissues. Our results suggest that the DOMADS genes play important roles in the process of floral transition.

Amino Acid Sequence↗

PubMed2000

DOH1, a class 1 knox gene, is required for maintenance of the basic plant architecture and floral transition in orchid.

We report here the isolation and identification of an orchid homeobox gene, DOH1, from Dendrobium Madame Thong-In. Analyses of its sequence and genomic organization suggest that DOH1 may be the only class 1 knox gene in the genome. DOH1 mRNA accumulates in meristem-rich tissues, and its expression is greatly downregulated during floral transition. In situ hybridization analysis demonstrates that DOH1 is also expressed in the incipient leaf primordia and is later detected in the same region of the inflorescence apex, as in DOMADS1. Overexpression of DOH1 in orchid plants completely suppresses shoot organization and development. Transgenic orchid plants expressing antisense mRNA for DOH1 show multiple shoot apical meristem (SAM) formations and early flowering. In addition, both the sense and antisense transformants exhibit defects in leaf development. These findings suggest that DOH1 plays a key role in maintaining the basic plant architecture of orchid through control of the formation and development of the SAM and shoot structure. Investigations of DOMADS1 expression in the SAM during floral transition reveal that the precocious flowering phenotype exhibited by DOH1 antisense transformants is coupled with the early onset of DOMADS1 expression. This fact, together with the reciprocal expression of DOH1 and DOMADS1 during floral transition, indicates that downregulation of DOH1 in the SAM is required for floral transition in orchid and that DOH1 is a possible upstream regulator of DOMADS1.

Amino Acid Sequence↗

PubMed2000

Innate lung defenses and compromised Pseudomonas aeruginosa clearance in the malnourished mouse model of respiratory infections in cystic fibrosis.

Cystic fibrosis (CF) is characterized by dysfunction of the digestive and respiratory tracts resulting in generalized malnutrition and chronic respiratory infections. Chronic lung infections with Pseudomonas aeruginosa, intense neutrophil-dominated airway inflammation, and progressive lung disease are the major cause of high morbidity and mortality in CF. Here we investigated the effects of malnutrition in CF on innate lung defenses, susceptibility to P. aeruginosa colonization, and associated inflammation, using aerosol models of acute and chronic infections in normal, malnourished, and transgenic mice. CFTR(m1Unc-/-) knockout mice displayed body weight variations and showed variable pulmonary clearance of P. aeruginosa. This variability was not detected in bitransgenic CFTR(m1Unc-/-)(FABP-hCFTR) mice in which the intestinal defect had been corrected. Diet-induced protein calorie malnutrition in C57BL/6J mice resulted in impaired pulmonary clearance of P. aeruginosa. Tumor necrosis factor alpha (TNF-alpha) and nitrite levels detected upon exposure to P. aeruginosa aerosols were lower in the lungs of the malnourished C57BL/6J mice relative than in lungs of mice fed a normal diet. The role of TNF-alpha and reactive nitrogen intermediates in P. aeruginosa clearance was tested in TNF-alpha and inducible nitric oxide synthase (iNOS) knockout mice. P. aeruginosa clearance was diminished in transgenic TNF-alpha- and iNOS-deficient mice. In contrast to the effects of TNF-alpha and iNOS, gamma interferon knockout mice retained a full capacity to eliminate P. aeruginosa from the lung. Malnutrition also contributed to excessive inflammation in C57BL/6J mice upon chronic challenge with P. aeruginosa. The repeatedly infected malnourished host did not produce interleukin-10, a major anti-inflammatory cytokine absent or diminished in the bronchoalveolar fluids of CF patients. These results are consistent with a model in which defective CFTR in the intestinal tract leads to nutritional deficiency which in turn contributes to compromised innate lung defenses, bacterial colonization, and excessive inflammation in the CF respiratory tract.

Administration, Inhalation↗

PubMed2000

Gene rearrangements in the vsa locus of Mycoplasma pulmonis.

The vsa genes of Mycoplasma pulmonis encode the V-1 lipoproteins. Most V-1 proteins contain repetitive domains and are thought to be involved in mycoplasma-host cell interactions. Previously, we have reported the isolation and characterization of six vsa genes comprising a 10-kb region of the genome of M. pulmonis strain KD735-15. In the current study, vsa-specific probes were used to clone several fragments from a genomic library of KD735-15 DNA and assemble a single 20-kb contig containing 11 vsa genes. The middle region of the vsa locus contains a large open reading frame (ORF) that is not a vsa gene and has undergone an internal deletion in some strains. The ORF is predicted to encode a membrane protein that may have a role in disease pathogenesis. To examine vsa genes in a strain of M. pulmonis that is unrelated to KD735-15, strain CT was studied. Through Southern hybridization and genomic cloning analyses, CT was found to possess homologs of the KD735-15 vsaA, -C, -E, and -F genes and two unique genes (vsaG and vsaH) that were not found in KD735-15. High-frequency, site-specific DNA inversions serve to regulate the phase-variable production of individual V-1 proteins. As a result of the sequence analysis of vsa recombination products, a model in which DNA inversion arises from strand exchange involving at least six nucleotides of the vrs box is proposed.

Bacterial Proteins↗

PubMed2000

A stem-loop motif formed by the immediate 5' terminus of the bovine viral diarrhea virus genome modulates translation as well as replication of the viral RNA.

Bovine viral diarrhea virus (BVDV), a Pestivirus member of the Flaviviridae family, has a positive-stranded RNA genome which consists of a single open reading frame (ORF) and untranslated regions (UTRs) at the 5' and 3' ends. The 5' UTR harbors extensive RNA structure motifs; most of them were shown to contribute to an internal ribosomal entry site (IRES), which mediates cap-independent translation of the ORF. The extreme 5'-terminal region of the BVDV genome had so far been believed not to be required for IRES function. By structure probing techniques, we initially verified the existence of a computer-predicted stem-loop motif at the 5' end of the viral genome (hairpin Ia) as well as at the 3' end of the complementary negative-strand replication intermediate [termed hairpin Ia (-)]. While the stem of this structure is mainly constituted of nucleotides that are conserved among pestiviruses, the loop region is predominantly composed of variable residues. Taking a reverse genetics approach to a subgenomic BVDV replicon RNA (DI9c) which could be equally employed in a translation as well as replication assay system based on BHK-21 cells, we obtained the following results. (i) Proper folding of the Ia stem was found to be crucial for efficient translation. Thus, in the context of an authentic replication-competent viral RNA, the 5'-terminal motif operates apparently as an integral functional part of the ribosome entry. (ii) An intact loop structure and a stretch of nucleotide residues that constitute a portion of the stem of the Ia or the Ia (-) motif, respectively, were defined to represent important determinants of the RNA replication pathway. (iii) Formation of the stem structure of the Ia (-) motif was determined to be not critical for RNA replication. In summary, our findings affirmed that the 5'-terminal region of the BVDV genome encodes a bifunctional secondary structure motif which may enable the viral RNA to switch from the translation to the replicative cycle and vice versa.

5' Untranslated Regions↗

PubMed2000

High rate of recombination throughout the human immunodeficiency virus type 1 genome.

The diploid nature of human immunodeficiency virus type 1 (HIV-1) indicates that recombination serves a central function in virus replication and evolution. Previously, while examining the nature of obligatory primer strand transfers during reverse transcription, a high rate of recombination was observed at the ends of the viral genome within the viral long terminal repeats, prompting the following question: does recombination occur at a high rate throughout the genome? To address this question, two vectors based upon different strains of HIV-1 were utilized. The vectors were comprised predominantly of autologous HIV-1 sequence and were approximately the same size as the parental genome. The proviral progeny of heterodimeric virions were analyzed after a single cycle of replication, and the sequence heterogeneity between the two strains allowed direct examination of recombination crossovers. The results obtained indicate that HIV-1 undergoes approximately two to three recombination events per genome per replication cycle. These results imply that both HIV-1 RNAs are typically utilized during reverse transcription and that recombination is an important aspect of HIV-1 replication.

Cell Line↗

PubMed2000

Human Na+/H+ exchanger genes : identification of polymorphisms by radiation hybrid mapping and analysis of linkage in end-stage renal disease.

The Na+/H+ exchangers (NHEs) are membrane-bound transporters that catalyze the electro-neutral movement of extracellular Na+ for intracellular H+. NHE genes play a critical role in pH homeostasis and cellular volume regulation and can be considered candidate genes for essential hypertension and renal disease. This study was performed to determine whether the NHE genes contributed to genetic susceptibility in end-stage renal disease (ESRD). To date, 5 isoforms of NHE have been cloned in mammals (NHE1 to NHE5). The complementary DNA (cDNA) sequences of NHE1 to NHE3 and NHE5 are known in humans. Because the chromosomal structure of the NHE genes is unknown, we used cDNA sequences to design polymerase chain reaction primers for use in radiation hybrid mapping. Radiation hybrid mapping of NHE genes identified nearby polymorphic markers for NHE1 to NHE3 (NHE1: D1S197, D1S2677; NHE2: D2S373, D2S1789; and NHE3: D5S678, D5S2005). We used these markers, and other previously identified polymorphic markers for NHE5, in linkage and association analyses of ESRD. The NHE1 to NHE3 and NHE5 loci did not demonstrate evidence for linkage to ESRD. However, NHE5 showed significant evidence for association (P</=1.0x10(-4)). The strongest evidence for association was observed with allele 6 of NHE5 (P</=0.001 to 0. 01). Allele 6 appeared to have a renoprotective effect, with a frequency of 0.15 in the control population and 0.06 to 0.09 in patients with ESRD. The combined approach of designing primers from cDNA and radiation hybrid mapping has proven successful in identifying polymorphisms for human genes of which only cDNA sequences were previously available. The NHE primers and associated polymorphic loci identified in this study can be used in genomic, linkage, and association analysis of NHE genes in future genetic studies of hypertension and renal failure. Given the allelic association, further evaluation of the role of NHE5 in ESRD susceptibility appears warranted.

Alleles↗

PubMed2000

Psychiatric morbidity and illness experience of primary care patients with chronic fatigue in Hong Kong.

OBJECTIVE: The authors' goal was to examine the prevalence and experience of psychiatric morbidity among primary care patients with chronic fatigue in Hong Kong. METHOD: One hundred adult patients with medically unexplained fatigue for 6 or more months were assessed with the Explanatory Model Interview Catalogue, psychopathological rating scales, and an enhanced version of the Structured Clinical Interview for DSM-III-R. RESULTS: The lifetime prevalence of DSM-III-R depressive and anxiety disorders was 54%. Current depressive and anxiety disorders were identified in 28 patients, who exhibited more psychopathology and functional impairment than other patients. Thirty-three patients had somatoform pain disorder, and 30 had undifferentiated somatoform disorder, but most of them could also be diagnosed as having shenjing shuairuo (weakness of nerves) and, to a lesser extent, ICD-10 neurasthenia. Chronic fatigue syndrome diagnosed according to the 1988 Centers for Disease Control criteria was rare (3%) and atypical. Generally, patients mentioned fatigue if asked, but pains (36%), insomnia (20%), and worries (13%) were the most troublesome symptoms. Most patients attributed illness onset to psychosocial sources. CONCLUSIONS: Psychiatric morbidity was common among primary care patients with chronic fatigue. Subthreshold psychiatric morbidity was very common and was more validly represented by the disease construct of shenjing shuairuo or neurasthenia than somatoform disorder.

Adolescent↗

PubMed2000

Perceptions of health and use of ambulatory care: differences between Korean and White elderly.

This study identifies whether culturally based differences in perceptions of health resulted in differences in ambulatory care use among the elderly. METHODS. The authors conducted stratified Poisson regressions on data from a 1992 survey of older Koreans and Whites in Los Angeles County. The models included measures of demographics, health, functioning, income, insurance, social support, and culture (perceptions of health or other beliefs). RESULTS. Descriptive findings showed older Koreans had more ambulatory physician visits, poorer functioning, and poorer perceptions of their health than Whites. Multivariate findings showed that positive perceptions of health independently reduced office visits for both Koreans and Whites, but the effect was significantly smaller for Koreans. Other cultural differences also affected use. DISCUSSION. The findings highlight differences between older Koreans and Whites' responses to physical and socioeconomic conditions and the importance of cultural sensitivity in the health care delivery system.

Aged↗

PubMed2000

A case of progressive systemic sclerosis complicated by massive pleural effusion with elevated CA125.

A tumor marker, CA125, is known to increase in the serum or other body fluids in various malignancies such as ovarian cancer. Here we present a case of progressive systemic sclerosis (PSS) with massive pleural effusion, in which CA125 in the serum and pleural fluid were elevated. The serum level of CA125 decreased in accordance with the change of the pleural effusion. CA125 level may be an indicator for the activity of serositis in some cases with collagen vascular diseases.

CA-125 Antigen↗

PubMed2000

Human macrovascular endothelial cells: optimization of culture conditions.

The purpose of this study is to identify optimal culture conditions to support the proliferation of human macrovascular endothelial cells. Two cell lines were employed: human saphenous vein endothelial cells (HSVEC) and human umbilical vein endothelial cells (HUVEC). The influence of basal nutrient media (14 types), fetal bovine serum (FBS), and mitogens (three types) were investigated in relation to cell proliferation. Additionally, a variety of extracellular matrix (ECM) substrate-coated culture dishes were also tested. The most effective nutrient medium in augmenting cell proliferation was MCDB 131. Compared to the more commonly used M199 medium, MCDB 131 resulted in a 2.3-fold increase in cell proliferation. Media containing 20% FBS increased cell proliferation 7.5-fold compared to serum-free media. Among the mitogens tested, heparin (50 microg/ml) and endothelial cell growth supplement (ECGS) (50 microg/ml) significantly improved cell proliferation. Epithelial growth factor (EGF) provided no improvement in cell proliferation. There were no statistical differences in cell proliferation or morphology when endothelial cells were grown on uncoated culture plates compared to plates coated with ECM proteins: fibronectin, laminin, gelatin, or collagen types I and IV. The culture environment yielding maximal HSVEC and HUVEC proliferation is MCDB 131 nutrient medium supplemented with 2 mM glutamine, 20% FBS, 50 microg/ml heparin, and 50 microg/ml ECGS. The ECM substrate-coated culture dishes offer no advantage.

Animals↗

PubMed2000

Alternative pathways of cell death to circumvent pleiotropic resistance in myeloma cells: role of cytotoxic T-lymphocytes.

Pleiotropic resistance to treatment remains one of the major reasons for therapeutic failures in patients with multiple myeloma. Myeloma cells are frequently resistant to physiological inducers of cell death prior to chemotherapy. Moreover, in the course of treatment cells acquire a multidrug resistant (MDR) phenotype, making eradication of the tumor even more difficult. A necessary prerequisite for circumventing complex pleiotropic resistance is therefore defining the signaling pathways that execute death in myeloma cells. This review discusses evidence that cytokine-expressing autologous tumor cell vaccine may be an efficient tool for elimination of both intrinsically resistant myeloma cells as well as cells with acquired MDR in murine models. The vaccine was similarly potent against wild type cells that were resistant to several death receptor ligands, and their isogenic sublines selected for P-glycoprotein-mediated MDR. The anti-myeloma effect of the vaccine was mediated by granzyme B/perforin-secreting cytotoxic T-lymphocytes. This is an example of therapeutic strategy directed at utilizing death pathways that are preserved in pleiotropically resistant tumor cells.

Cell Death↗

PubMed2000

Heterogeneous populations of ES cells in the generation of a floxed Presenilin-1 allele.

Generation of a floxed Presenilin-1 (PS1) allele involved two recombination events in the embryonic stem (ES) cells. First, a targeting vector containing a loxP site in intron 1 and a floxed CMV-HYG/TK double selection cassette in intron 3 was integrated into the PS1 locus by homologous recombination. The use of a negative selection cassette, PGK-DTA, dramatically increased the recombination efficiency within the targeted locus (75-fold). Second, an expression vector encoding Cre recombinase was introduced to excise the floxed CMV-HYG/TK cassette via site-specific recombination. However, all five ES cell clones testing positive for the proper removal of the CMV-HYG/TK cassette also contained a proportion of ES cells in which recombination had occurred between the distal loxP sites in introns 1 and 3, resulting in excision of the entire floxed region. It is therefore critical to screen for possible recombination events involving all 3 loxP sites, in order to identify ES cells clones bearing high proportions of the desired ES cells. genesis 26:5-8, 2000.

Alleles↗

PubMed2000

Dramatic suppression of plasma and urinary prostate specific antigen and human glandular kallikrein by antiandrogens in male-to-female transsexuals.

PURPOSE: Prostate specific antigen (PSA) and human glandular kallikrein (hK2) are mainly produced by the prostate and their genes are regulated by androgens through the androgen receptor. We determine whether PSA and hK2 change significantly in plasma and urine after antiandrogen treatment in male-to-female transsexuals. MATERIALS AND METHODS: Plasma and urine PSA and hK2 were measured with highly sensitive immunofluorometric procedures capable of detecting within 1 or 6 ng./l. PSA or hK2, respectively. Study groups consisted of 10 men treated with cyproterone acetate only (group 1), 15 transdermal estradiol plus cyproterone acetate (group 2) and 31 ethinyl estradiol plus cyproterone acetate (group 3). Plasma and urine samples were collected before initiation of treatment as well as after 4 months of hormonal therapy. For a subset of group 3 patients blood and urine samples were also obtained after 12 months of treatment. RESULTS: Cyproterone acetate, a steroidal antiandrogen, alone or with estradiol was able to suppress greater than 90% of plasma and urinary PSA and hK2 concentration after 4 or 12 months of therapy. CONCLUSIONS: Cyproterone acetate therapy causes dramatic suppression of plasma and urinary PSA and hK2 in men without prostate cancer. Since cyproterone acetate is used for prostate cancer treatment, suppression of PSA after hormonal therapy may not accurately reflect therapy success in reducing tumor burden.

Adolescent↗

PubMed2000

Serum total and free prostate-specific antigen for breast cancer diagnosis in women.

Prostate-specific antigen (PSA) is a serine protease expressed at high levels in prostate epithelium, and elevated PSA in serum is a well-established marker of prostate cancer. Recently, the relative proportions of free PSA and PSA complexed to the serine protease inhibitor alpha 1-antichymotrypsin have become important variables in distinguishing between prostate cancer and benign prostatic hyperplasia. Numerous studies have demonstrated the production of PSA in female tissues such as the breast, and low levels of PSA are present in female sera. The objective of this study was to measure and compare the relative proportions of free PSA and PSA complexed to the serine protease inhibitor alpha 1-antichymotrypsin in the serum of women with breast cancer or benign breast disease or women with no known malignancies. PSA was measured with an established immunoassay for total PSA and a novel immunoassay for free PSA, both of which had a detection limit of 0.001 microgram/liter (1 ng/liter). The percentage of breast cancer patients with free PSA as the predominant molecular form (> 50% of total PSA) in serum was five times higher than that of healthy women or women with benign breast disease, and PSA decreased in the serum of breast cancer patients after surgery. The diagnostic use of free PSA for breast cancer is limited at this point, due to the low diagnostic sensitivity (approximately 20%); however, free PSA as the predominant molecular form shows a high diagnostic specificity (approximately 96%) in comparison to women free of breast cancer or with benign breast disease. These results suggest that the clinical applicability of free PSA for breast cancer diagnosis and the biological mechanism behind its increase should be further investigated.

Adult↗