Biomedical subjects

Z Yuan

Publications and source records attributed to Z Yuan.

At least 91 records · Page 5Linked to original sources

PubMed2000

Agreement of Medicare claims and tumor registry data for assessment of cancer-related treatment.

BACKGROUND: Although health claims data are increasingly used in evaluating variations in patterns of cancer care and outcomes, little is known about the comparability of these data with tumor registry information. OBJECTIVES: To evaluate the agreement between Medicare claims and tumor registry data in measuring patterns of diagnostic and therapeutic procedures for older cancer patients. RESEARCH DESIGN: Analysis of a database linking Surveillance, Epidemiology and End Results (SEER) registry data and Medicare claims in patients aged > or =65 years with cancer. SUBJECTS: 361,255 Medicare patients with invasive breast, colorectal, endometrial, lung, pancreatic, and prostate cancer diagnosed between 1984 and 1993. MEASURES: Concordance of SEER files with corresponding Medicare claims. RESULTS: Medicare claims generally identified patients who underwent resection and radical surgery according to SEER (ie, concordance > or =85%-90%) but less likely biopsy or local excision (ie, concordance < or =50%). In some instances, claims also categorized patients as having more invasive surgery than was listed in SEER and also provided incremental information about the use of surgical treatment after 4 months. SEER files and, to a lesser degree, Medicare claims identified radiation therapy not included in the other data source, and Medicare files also captured a significant number of patients with codes for chemotherapy. CONCLUSIONS: Medicare files may be appropriate for studies of patterns of use of surgical treatment, but not for diagnostic procedures. The potential benefit of Medicare claims in identifying delayed surgical intervention and chemotherapy deserves further study.

Aged↗

PubMed2000

Peptide deformylase in Staphylococcus aureus: resistance to inhibition is mediated by mutations in the formyltransferase gene.

Peptide deformylase, a bacterial enzyme, represents a novel target for antibiotic discovery. Two deformylase homologs, defA and defB, were identified in Staphylococcus aureus. The defA homolog, located upstream of the transformylase gene, was identified by genomic analysis and was cloned from chromosomal DNA by PCR. A distinct homolog, defB, was cloned from an S. aureus genomic library by complementation of the arabinose-dependent phenotype of a P(BAD)-def Escherichia coli strain grown under arabinose-limiting conditions. Overexpression in E. coli of defB, but not defA, correlated to increased deformylase activity and decreased susceptibility to actinonin, a deformylase-specific inhibitor. The defB gene could not be disrupted in wild-type S. aureus, suggesting that this gene, which encodes a functional deformylase, is essential. In contrast, the defA gene could be inactivated; the function of this gene is unknown. Actinonin-resistant mutants grew slowly in vitro and did not show cross-resistance to other classes of antibiotics. When compared to the parent, an actinonin-resistant strain produced an attenuated infection in a murine abscess model, indicating that this strain also has a growth disadvantage in vivo. Sequence analysis of the actinonin-resistant mutants revealed that each harbors a loss-of-function mutation in the fmt gene. Susceptibility to actinonin was restored when the wild-type fmt gene was introduced into these mutant strains. An S. aureus Deltafmt strain was also resistant to actinonin, suggesting that a functional deformylase activity is not required in a strain that lacks formyltransferase activity. Accordingly, the defB gene could be disrupted in an fmt mutant.

Amidohydrolases↗

PubMed2000

The N-terminal domain of p73 interacts with the CH1 domain of p300/CREB binding protein and mediates transcriptional activation and apoptosis.

The newly identified p53 homolog p73 mimics the transcriptional function of p53. We have investigated the regulation of p73's transcriptional activity by p300/CREB binding protein (CBP). p73-p300 complexes were identified in HeLa cell extracts by cofractionation and coimmunoprecipitation assays. The p73-p300 interaction was confirmed in vitro by glutathione S-transferase-protein association assays and in vivo by coimmunoprecipitating the overexpressed p300 and p73 in human p53-free small-cell lung carcinoma H1299 or osteosarcoma Saos-2 cells. The N terminus but not the N-terminal truncation of p73 bound to the CH1 domain (amino acids [aa] 350 to 450) of p300/CBP. Accordingly, this p73 N-terminal deletion was unable to activate transcription or to induce apoptosis. Overexpression of either p300 or CBP stimulated transcription mediated by p73 but not its N-terminally deleted mutant in vivo. The N-terminal fragment from aa 19 to 597, but not the truncated fragment from aa 242 to 1700 of p300, reduced p73-mediated transcription markedly. p73-dependent transcription or apoptosis was partially impaired in either p300- or CBP-deficient human breast carcinoma MCF-7 or H1299 cells, suggesting that both coactivators mediate transcription by p73 in cells. These results demonstrate that the N terminus of p73 directly interacts with the N-terminal CH1 domain of p300/CBP to activate transcription.

Apoptosis↗

PubMed2000

[Exploration of the mechanism of skin expansion].

OBJECTIVE: In order to explore the mechanism of skin expansion technique (SET). METHODS: Domestic dogs were used in this experiment. The epidermal mitotic activity, capillary blood flow change of the expanded flap were observed with microspectrophotometer and radioactive microsphere technique. RESULTS: 1. The epidermis of expanded skin was significantly thicker than that of other groups (P < 0.05). 2. The epidermal mitotic activity was elevated significantly(P < 0.01). 3. The capillary blood flow of expanded flaps increased significantly (P < 0.01). CONCLUSIONS: 1. The surplus skin produced by SET is the result of replication, not compensation. 2. SET increases skin blood flow, therefore enlarges the survival area of an expanded flap.

Animals↗

PubMed2000

[Neural electrophysiological observations on the external anal sphincter in patients with anorectal malformation].

OBJECTIVE: To explore the functional damage of the nerves controlling external anal sphincter in patients with congenital anorectal malformation and to design a new method for measuring the conductive time of sacral spinal center in the pudendo-anal reflex arc. METHODS: 45 patients with anorectal malformation and 20 normal subjects were subjected to detect the latency for pudendo-anal reflex, spinal-anal response and evoked potential of caude equine simultaneously. The conduction time of afferent motor nerve, efferent sense nerve and sacral spinal center in the pudendo-anal reflex arc were quantitatively analyzed. RESULTS: The normal latency for pudendo-anal reflex was 23.3 +/- 6.9 ms, for spinal-anal response was 4.6 +/- 1.9 ms, and for evoked potential of caude equine was 3.8 +/- 0.9 ms. The conduction time of sacral spinal center was 14.8 +/- 6.6 ms. In patients with anorectal malformation, the latencies were prolonged obviously, especially the conduction time of sacral spinal center. There was a significant negative correlation between the latency and clinical scores. The correlation coefficient for pudendo-anal reflex was -0.68, for spinal-anal response was -0.64, and for conduction time of sacral spinal center was -0.60. CONCLUSIONS: The abnormality of nerves serving anal sphincters was one of the important causes for postoperative fecal incontinence. The neural lesions are specially serious in the sacral spinal center.

Adolescent↗

PubMed2000

[Detection of K-ras gene mutations in DNA extracted from the plasma of patients with pancreatic cancer].

OBJECTIVES: To detect mutations of the K-ras codon 12 in DNA extracted from the plasma of patients with pancreatic cancer, and to explore the possibility of using this method in early diagnosis of pancreatic cancer. METHODS: Plasma DNA was isolated from the blood of 22 patients with pancreatic cancer and from 20 normal controls. K-ras codon 12 mutations were detected by mutant enriched polymerase chain reaction-restriction fragment length polymorphism technique and subsequent product sequencing. The relation of K-ras mutations in plasma to clinical features in pancreatic cancer patients was analyzed. RESULTS: Seventeen (77.3%) of 22 patients with pancreatic cancer had a codon 12 K-ras mutation in their plasma DNA. In two patients, the PCR products were sequenced and the mutations were confirmed. The occurrence of K-ras mutations in the plasma DNA was not related to tumor location, tumor size, and TNM stage. No K-ras mutation was detected in the plasma specimen of any of the normal controls. CONCLUSIONS: K-ras mutations are frequently found in the plasma DNA of patients with pancreatic cancer. Analysis of K-ras mutation in the plasma DNA may be useful in the early detection of pancreatic cancer.

Adult↗

PubMed2000

[CT guided percutaneous fine needle aspiration for early diagnosis of pancreatic infection after acute necrotizing pancreatitis].

OBJECTIVE: To assess CT-guided percutaneous fine needle aspiration (FNA) for early diagnosis of pancreatic infection after acute necrotizing pancreatitis. METHODS: CT-guided percutaneous FNA was employed to diagnose pancreatic infection after acute necrotizing pancreatitis in 14 patients. The aspirates were smeared, cultured and subjected polymerase to chain reaction (PCR) for detecting bacteria. RESULTS: Ten patients were diagnosed as having pancreatic infection and 4 non-pancreatic infection. FNA was totally performed for 15 times: left retroperitoneal route for 12 times, left and right retroperitoneal route for one time, and transperitoneal route for two times. The sensitivity of smear, PCR, culture to diagnose pancreatic infection was 7/10, 9/10, 10/10, respectively. Their specificity was 4/4, and the time for obtaining the results was 30 minutes, 4 hours, 3 days respectively. CONCLUSIONS: Retroperitoneal approach can be used for most patients with acute necrotizing pancreatitis when performing CT guided-percutaneous FNA. PCR of aspirates is a rapid and accurate method to diagnose pancreatic infection.

Adult↗

PubMed2000

[A study on the determination method of biological function of BRF].

This study was aimed to establish a method for determining the biological function of biological wave regulating factor (BRF). Proteus mirabilis was used to set up the experimental model. The biological function of the component obtained from wave growth media beneath the bacterial colony rings resulting from bacterial proliferation was determined in biological wave test by analytically microbiological method. The results indicated that BRF could enhance biological wave and shorten its period. The method is of some value in studying the regulative mechanism of biological wave.

Bacterial Proteins↗

PubMed2000

[The histological changes after preserved human amniotic membrane transplantation for conjunctival reconstruction of rabbits eyes].

PURPOSE: To investigate the histological changes after preserved human amnotic membrane transplantation of rabbit eyes. METHODS: The conjunctiva of 12 New Zealand albino rabbits' right eyes were excised partly. Then the preserved human amniotic membrane were transplanted on the sclera. Eyes were enucleated at 1 week, 3 weeks, 5 weeks and 12 weeks (n = 3 for each) after surgery, and they were examined histologically with staining of HE, PAS, and transmission electronic microscopy. RESULTS: At 1 week after transplantation, the human amniotic membrane firmly attached on the sclera, with the dead epithelial cells remaining on its surface. At 3 weeks, conjunctival epithelization was completed on the human amniotic membrane. Abundant PAS-positive goblet cells were recognized. The amnion began resolve. At 12 weeks, the amnion dissolved. On transmission electronic microscopy, the cell polarity is prominent. The epithelial cells contained a large number of mitochondria and endoplasmic reticulum. Microvilli were pronounced on the apical cell membrane. There are many intracellular desmosomes and hemidesmosomes. CONCLUSION: Preserved human amniotic membrane is a valuable conjunctival replacement material. After transplantation, the histology of new tissue is as same as normal conjunctive.

Amnion↗

PubMed2000

[Clinical analysis of evisceration with hydroxyapatite implant].

PURPOSE: To evaluate the clinical effect and safety of evisceration with hydroxyapatite (HA) orbital implant. METHODS: A retrospective analysis of all eviscerations with HA implant performed between January 1998 and May 2000 in Zhongshan Ophthalmic Center was completed. Patient records were reviewed for demographic data, surgical indication, sphere size, clinical outcome, and complications. The average follow-up interval was 11.6 months (2-24 months). RESULTS: Primary evisceration with HA implantation was performed in total 78 cases. All patients underwent successful surgery without major complications. There was no case with those complications, including implant extrusion, exposure and implant dislocation, in the series examination. No patient has symphathetic ophthalmia during follow-up interval. CONCLUSION: In strict selected cases with surgical indication of evisceration, primary evisceration with HA implantation is a safe and effective method for treating patients with a blind, painful or atrophic eye.

Adolescent↗

PubMed2000

[Study on the effect of aging on the crystallization behavior of syndiotactic polystyrene with in situ FTIR measurement].

The effect of aging on the crystallization of syndiotactic polystyrene (SPS) in glassy state and delta form was investigated with in situ FTIR. It is shown that both aged sample and unaged sample in glassy state show the same crystallization behavior; whereas for samples in delta form, the aged sample crystallized in higher temperature range than the unaged sample does. This result is correlated with the formation of a more stable complex structure which formed by combining the molecules and the solvents even more tightly during the aging process, and hence the release of the solvents occurs at higher temperature to cause the crystal transition from the solvent-included delta form to the solvent-free gamma form. However, the aging process has on effect on the following crystal transition from gamma form to alpha form.

Chemical Phenomena↗

PubMed1999

On-line estimation of the maximum specific growth rate of nitrifiers in activated sludge systems.

The on-line estimation of the maximum specific growth rate of autotrophic biomass is addressed in this article. A general nitrification process model, which is valid for any realistic flow pattern, is used to develop the estimation algorithm. Depending on the measurements available, two estimation equations are derived. While both require measuring the nitrification activity of the activated sludge, one requires the additional measurement of the nitrifiable nitrogen concentrations at the two ends of the bioreactor, and the other requires the nitrate nitrogen concentrations at the same locations. The algorithm also requires some stoichiometric and kinetic parameters. However, sensitivity analysis shows that the estimate is insensitive to the parameters other than the autotrophic decay rate. Compared to the existing algorithms, the algorithm developed in this article does not rely on the assumption of ideal flow pattern in the plant and does not require an error-prone estimate of the autotrophic biomass concentration. Experimental and simulation studies show that the algorithm performs well and is robust to influent variations and accidental sludge losses.

Algorithms↗

PubMed1999

Colorectal carcinoma screening attitudes and practices among primary care physicians in counties at extremes of either high or low cancer case-fatality.

BACKGROUND: To the authors' knowledge, physician attitudes and reported practices regarding colorectal carcinoma screening have not been studied in areas of highest risk for cancer death. METHODS: Medicare claims were used to calculate colorectal carcinoma 2-year case-fatality rates for counties with >100 incident cases of colorectal carcinoma between 1991-1993. All 2682 practicing primary care physicians in 20 counties with the lowest case-fatality rates (mean of 29.9%) and 19 counties with the highest case-fatality rates (mean of 47.8%) were surveyed regarding their screening procedures and attitudes. RESULTS: Among the 972 respondents (36.1%), the reported use of fecal occult blood testing (FOBT) and flexible sigmoidoscopy was similar in the low and high case-fatality counties. However, physicians who practiced in the high case-fatality counties were less likely to be trained in and to perform sigmoidoscopy themselves (37.0% vs. 45.6%; P<0.01). Moreover, practitioners in the high case-fatality counties were more likely than the other physicians to consider or plan enhanced FOBT and sigmoidoscopic screening in the near future. FOBT and sigmoidoscopy screening rates at the county level were associated negatively with cancer incidence rates, case-fatality rates, and metastatic disease rates, suggesting a potentially protective effect. CONCLUSIONS: Geographically targeted interventions are a potentially cost-effective strategy for focusing additional screening services on the highest risk populations. The primary care clinicians in these high risk areas are logical partners for these interventions by virtue of their high degree of readiness to change their current screening practices.

Attitude to Health↗

PubMed1999

[Study of the 3'noncoding region of Chinese hepatitis C virus genome].

OBJECTIVE: To analyze the 3' noncoding region (3' NCR) of HCV genome from Chinese hepatitis C patients so as to facilitate further study of mechanism of HCV gene replication. METHODS: Two different strategies were employed to amplify the full-length of the 3' noncoding region of HCV genome from sera of HCV infected patients in Shanghai area: one was to amplify the full-length fragment directly by nested PCR and the other amplify two overlapping fragments. The PCR products were further analyzed by sequencing and nucleotide alignments. A HCV genome 3'NCR based RT-PCR was developed and its specificity and sensitivity for HCV RNA detection in sera was compared with the established 5'NCR based RT-PCR. RESULTS: Sequence analysis showed that Chinese HCV genomic 3' NCR consists of three parts: the 5' region, poly (U-UC) tract and the 98-base region. Sequence alignments revealed that, while the 98-base regions were completely conserved in different isolates and were identical to the reported sequences, the poly (U-UC) region shared highly diversities. A high degree of concordance(95%) between the 3'NCR and 5'NCR RT-PCR for detection of HCV RNA in sera was found. CONCLUSION: The high conservation at the 3' NCR(98 bases) of HCV genome among different isolates indicated that this region may be critical for HCV gene replication The 3'NCR based RT-PCR may be a useful addition to available systems to diagnosis HCV infection.

3' Untranslated Regions↗

PubMed1999

Geographic and patient variation among Medicare beneficiaries in the use of follow-up testing after surgery for nonmetastatic colorectal carcinoma.

BACKGROUND: There are a paucity of data supporting the routine use of follow-up testing to detect recurrent disease after potentially curative initial surgery in patients with nonmetastatic colorectal carcinoma. METHODS: Using the population-based Surveillance, Epidemiology, and End Results (SEER) registry, all patients age > or =65 years with local or regional colorectal carcinoma who were diagnosed in 1991, underwent surgical resection, and survived at least 6 months after diagnosis were identified. All inpatient, hospital outpatient, and physician/supplier Medicare claims from 6 months after diagnosis through 1994 were examined for follow-up procedures of interest. Procedure use during follow-up was compared across patient groups using both bivariate and multivariate analyses. RESULTS: A total of 5716 patients were identified, with 1.3% found to have developed subsequent primary tumors of the colon or rectum, and 74% surviving through 1994. One or more procedures of interest were performed in 88% of patients; the most commonly performed tests were liver enzymes, chest X-rays, colonoscopy, and computed tomography scans. Lower rates of testing generally were observed with older age groups, patients with fewer comorbidities, and patients who did not survive through the follow-up period. Among all procedures studied, there also was significant variation in the rates of testing across the 9 SEER areas, varying from 1.5-fold to 3.6-fold. The geographic variation persisted in multivariate models adjusting for potentially confounding factors. CONCLUSIONS: The current study found significant variability in the use of follow-up procedures, with the most striking differences apparent across geographic regions. Further studies are needed to determine the underlying reasons for the disparities, as well as the impact of surveillance on patient outcomes.

Age Factors↗

PubMed1999

Prediction of protein subcellular locations using Markov chain models.

A novel method was introduced to predict protein subcellular locations from sequences. Using sequence data, this method achieved a prediction accuracy higher than previous methods based on the amino acid composition. For three subcellular locations in a prokaryotic organism, the overall prediction accuracy reached 89.1%. For eukaryotic proteins, prediction accuracies of 73.0% and 78.7% were attained within four and three location categories, respectively. These results demonstrate the applicability of this relative simple method and possible improvement of prediction for the protein subcellular location.

Markov Chains↗

PubMed1999

Enhanced therapeutic efficacy of tumor RNA-pulsed dendritic cells after genetic modification with lymphotactin.

Pulsing dendritic cells (DCs) with tumor cell-derived mRNA is regarded as an attractive alternative in the development of DC-based tumor vaccines. Our aim is to improve the therapeutic efficacy of DC-based tumor RNA vaccines by augmenting the preferential chemotaxis of DCs to T cells. Mouse bone marrow-derived DCs were genetically modified with lymphotactin (Lptn) by adenovirus vector, which conferred on DCs preferential chemotaxis to CD4+ and CD8+ T cells (Cao et al., 1998). Lptn gene-modified DCs (Lptn-DCs) were pulsed with tumor mRNA and used for vaccination in the tumor models of 3LL lung carcinoma and B16 melanoma. In both tumor models, immunization with 4 X 10(4) tumor RNA-pulsed Lptn-DCs induced more potent CTL activity, compared with their counterparts, specifically against tumor cells and Mut1 or tyrosinase-related protein 2 (TRP-2) peptide-pulsed RMA-S cells, and rendered the immunized mice resistant to tumor challenge much more effectively. CD8+ T cells were necessary and sufficient to generate the protection of Lptn-DC-based RNA tumor vaccines, and CD4+ T cells were required for the induction of tumor rejection. In the preestablished 3LL and B16 tumor models, vaccination with DC-based or LacZ-DC-based tumor RNA vaccines (2 X 10(5) cells) could reduce pulmonary metastasis and extend survival of tumor-bearing mice, but was less effective than the Lptn-DC counterpart (with 60-80% mice surviving). When the immunizing dose was decreased to 4 X 10(4) cells, Lptn-DC-based tumor vaccines rather than their counterparts were still significantly effective. Our studies provide a potential strategy to improve the efficacy of DC-based vaccines, and a new approach to immunological intervention by chemokines.

Adenoviridae↗

PubMed1999

The presence of the Rb c-box peptide in the cytoplasm inhibits p210bcr-abl transforming function.

In order to test if the carboxyl terminal polypeptide of the Retinoblastoma (Rb) tumor suppressor protein, could be used to suppress the growth factor-independent growth phenotype of p210bcr-abl positive myeloid cells, we introduced a truncated form of the 3' end of the Rb cDNA encoding its last 173 amino acid residues (Rb C-box) which localize into the cytoplasm where the p210bcr-abl transforming protein is found, into myeloid cells (32D) which depends on the p210bcr-abl protein for IL3 growth factor-independent growth (32D-p210). The expression of the plasmid vectors carrying the Rb C-box cDNAs was shown to inhibit the abl tyrosine specific protein kinase activity of the p210(bcr-abl) oncoprotein and to suppress the IL3-independent growth phenotype of the 32D-p210 cells. The Rb C-box polypeptides did not suppress the growth of the untransfected 32D parental cell line in methylcellulose in the presence of IL3-conditioned medium. These results suggest that the cytoplasmic localization of the p210(bcr-abl) allows it to escape the effect of intranuclear proteins such as Rb which negatively regulate the p145(c-abl) kinase.

Animals↗