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Biomedical subjects

D Lin

Publications and source records attributed to D Lin.

At least 73 records · Page 4Linked to original sources
PubMed2000

[Genetic polymorphism in hOGG1 and susceptibility to esophageal cancer in Chinese].

OBJECTIVE: To examine the association between Ser326Cys polymorphism in hOGG1 gene, which is involved in the repair of 8-hydroxyguanine in damaged DNA, and investigate the risk of squamous cell carcinoma of the esophagus in Chinese. METHODS: Ser326Cys polymorphism in hOGG1 gene was determined by PCR-SSCP approach among 201 normal controls and 196 patients with squamous cell carcinoma of the esophagus. The association between this genetic polymorphism and the risk of the cancer was examined by a multivariate analysis. RESULTS: The Cys/Cys genotype of hOGG1 was found in 21.4% of patients with the cancer and in 13.4% of controls (P<0.05). Homozygosity for the Cys/Cys genotype significantly increased the risk of developing esophageal cancer, with the odds ratio adjusted for age, sex and smoking being 1.9(95% CI 1.3-2.6). Smoking also significantly increased esophageal cancer risk in this case-control study (adjusted OR 2.6; 95% CI 1.7- 3.9). No interaction between smoking and Cys/Cys genotype was observed for the risk of esophageal cancer. CONCLUSION: Polymorphism of hOGG1 Ser326Cys may play a role in esophageal carcinogenesis.

Adult↗
PubMed2000

[The effect of polylactide screws on fracture healing].

This experiment aimed at investigating the effect of a kind of home-bred poly-DL-lactide screws on fracture healing. An operation was performed so as to make bilateral lateral condylar fractures of the femur in 8 dogs. The left sides were fixed with 2 home-bred PDLLA(Mv = 43 x 10(4)) screws, and the contralateral sides were fixed with 2 metalic screws to be used as controls. The animals were sacrificed at 2, 4, 8, and 12 weeks after surgery. Optic microscopy and SEM photography were done. The results of optic microscopy showed that fibrous callus formed already in both groups by 2 weeks after surgery, and bilateral fractures united uneventfully by 12 weeks. Although the course of fracture healing in experimental group was slower than that in control group, the osteogenesis in experimental group appeared to be normal. The SEM examination demonstrated that collagenous fibers arranged regularly and calcified normally in both groups at 12 weeks. And many square and rhomboid granules produced from the degradation of PDLLA material were found in experimental group at 12 weeks. Therefore, it is suggested that this kind of home-bred PDLLA screws should be applicable to fractures where the tissues are rich in blood supply.

Animals↗
PubMed2000

[Geographic information systems spatial analysis on transmission of schistosomiasis in China].

OBJECTIVE: To understand the epidemiologic status and geographical distribution of schistosomiasis in China. METHODS: Relevant detabases were set up after collection of data from two National Sampling Surveys on Schistosomiasis, in 1989 and 1995. Spatial analysis was undertaken after the database linked to the GIS software which was supported by Arc View 3.0a. Correlation analysis was performed to understand the relationship between rates of human infection and cattle infection. RESULTS: The epidemic areas of schistosomiasis with high risk are mainly distributed in the marshland along the Yangtze River and can be identified as five spatial distribution regions based on the results of spatial analysis. Both epidemic areas and positive rates of stool examination in cattle and water buffalo are much wider and higher than that in humans. The positive correlation was seen between infection rate in human and in cattle from data of both sampling surveys. CONCLUSION: The relevant strategy for schistosomiasis control in different spatial regions should be performed accordingly and the measures of control for cattle and water buffalo should be strengthened in the endemic areas.

Adolescent↗
PubMed2000

[Experimental studies on exons 5-8 of p53 gene mutation in laryngeal squamous cell carcinoma].

This study was designed to detect the point mutations of exons 5-8 of p53 gene in laryngeal squamous cell carcinoma (LSCC) and analyze their relationship. The detection of fresh tumor samples from LSCC patients was performed using silver staining PCR-SSCP method. From among 60 patients samples, 47 were positive in SSCP. Mutation rate was 78.3% (47/60). The results showed that the prevalence of p53 mutations in LSCC subjected to silver staining PCR-SSCP test were 50% (30/60) in exon 5, 11.67%(7/60) in exon 6, 41.6%(25/60) in exon 7, and 25%(15/60) in exon 8. The majority of the mutations were found in exon 5 and exon 7. Exon 5 and exon 7 of p53 gene may be the mutation hotspot in LSCC; they may be the critical position easily attacked by some carcinogen factors relating to LSCC.

Carcinoma, Squamous Cell↗
PubMed2000

[Detection of bcl-2/JH gene rearrangement by semi-nested polymerase chain reaction from fresh tumor samples in patients with laryngeal squamous cell carcinomas].

OBJECTIVE: To evaluate the clinical implications of bcl-2/JH gene rearrangement in laryngeal squamous cell carcinomas (LSCC). METHODS: Bcl-2/JH gene rearrangement analysis in fresh tumor samples was performed in 60 patients with LSCC by semi-nested polymerase chain reaction(PCR). RESULTS: The results showed that bcl-2/JH gene rearrangement was found in 37 out of 60 patients. The breakpoint was located within the major breakpoint region(mbr) in 33 of the 60 patients and the remaining patients had bcl-2 translocation within the minor cluster region(mcr). The results of the study showed that the rearrangement rate of bcl-2 gene was not related to the grade of differentiation, clinical stage, and neck lymph-node metastasis (P > 0.05), and it was related to heavy smoking (P < 0.05). CONCLUSION: Detection of bcl-2/JH gene rearrangement could reveal that bcl-2/JH fusion gene in LSCC is an important molecular biological marker and has a significant role in occurrence and development of LSCC.

Adult↗
PubMed2000

[FTIR spectra of SO4(2-)/Fe2O3 nanosolid superacid].

The nanosolid superacid SO4(2-)/Fe2O3 was prepared by using nanometer chemical precursor FeO(OH)2 put in the SO4(2-) solution and dried. IR spectra of samples was determined with different calcination temperature, calcination time and with different concentration SO4(2-) solutions. They are different from IR of normal solid superacid. Then a good analysis and discussion are done.

English Abstract↗
PubMed1999

Functional consequences of troponin T mutations found in hypertrophic cardiomyopathy.

Missense mutations in the cardiac thin filament protein troponin T (TnT) are a cause of familial hypertrophic cardiomyopathy (FHC). To understand how these mutations produce dysfunction, five TnTs were produced and purified containing FHC mutations found in several regions of TnT. Functional defects were diverse. Mutations F110I, E244D, and COOH-terminal truncation weakened the affinity of troponin for the thin filament. Mutation DeltaE160 resulted in thin filaments with increased calcium affinity at the regulatory site of troponin C. Mutations R92Q and F110I resulted in impaired troponin solubility, suggesting abnormal protein folding. Depending upon the mutation, the in vitro unloaded actin-myosin sliding speed showed small increases, showed small decreases, or was unchanged. COOH-terminal truncation mutation resulted in a decreased thin filament-myosin subfragment 1 MgATPase rate. The results indicate that the mutations cause diverse immediate effects, despite similarities in disease manifestations. Separable but repeatedly observed abnormalities resulting from FHC TnT mutations include increased unloaded sliding speed, increased or decreased Ca(2+) affinity, impairment of folding or sarcomeric integrity, and decreased force. Enhancement as well as impairment of contractile protein function is observed, suggesting that TnT, including the troponin tail region, modulates the regulation of cardiac contraction.

Amino Acid Sequence↗
PubMed1999

The carboxyl terminus of B class ephrins constitutes a PDZ domain binding motif.

Ephrin B proteins function as ligands for B class Eph receptor tyrosine kinases and are postulated to possess an intrinsic signaling function. The sequence at the carboxyl terminus of B-type ephrins contains a putative PDZ binding site, providing a possible mechanism through which transmembrane ephrins might interact with cytoplasmic proteins. To test this notion, a day 10.5 mouse embryonic expression library was screened with a biotinylated peptide corresponding to the carboxyl terminus of ephrin B3. Three of the positive cDNAs encoded polypeptides with multiple PDZ domains, representing fragments of the molecule GRIP, the protein syntenin, and PHIP, a novel PDZ domain-containing protein related to Caenorhabditis elegans PAR-3. In addition, the binding specificities of PDZ domains previously predicted by an oriented library approach (Songyang, Z., Fanning, A. S., Fu, C., Xu, J., Marfatia, S. M., Chishti, A. H., Crompton, A., Chan, A. C., Anderson, J. M., and Cantley, L. C. (1997) Science 275, 73-77) identified the tyrosine phosphatase FAP-1 as a potential binding partner for B ephrins. In vitro studies demonstrated that the fifth PDZ domain of FAP-1 and full-length syntenin bound ephrin B1 via the carboxyl-terminal motif. Lastly, syntenin and ephrin B1 could be co-immunoprecipitated from transfected COS-1 cells, suggesting that PDZ domain binding of B ephrins can occur in cells. These results indicate that the carboxyl-terminal motif of B ephrins provides a binding site for specific PDZ domain-containing proteins, which might localize the transmembrane ligands for interactions with Eph receptors or participate in signaling within ephrin B-expressing cells.

Amino Acid Sequence↗
PubMed1999

Differential effects of withdrawal from chronic amphetamine or fluoxetine administration on brain stimulation reward in the rat--interactions between the two drugs.

RATIONALE: Withdrawal from chronic amphetamine administration is characterized by deficits in reward that resemble some symptoms of depression. Nevertheless, the effects of long-term administration and withdrawal from other drugs, such as fluoxetine, that have the potential to elevate mood in depressed individuals have not been characterized. OBJECTIVES: The purpose of this study was to characterize the effects of withdrawal from chronic amphetamine or fluoxetine administration on central reward function. Furthermore, the effects of acute or chronic pretreatment with fluoxetine on responsiveness to an acute amphetamine challenge were examined to identify potential interactions between the two drugs. METHODS: A rate-independent discrete-trial threshold procedure was used to characterize self-stimulation behavior in rats prepared with bipolar electrodes in the medial forebrain bundle. RESULTS: Elevations in intracranial self-stimulation (ICSS) thresholds, reflecting a decrease in the reward value of the stimulation, were associated with withdrawal from various chronic amphetamine treatment regimens (1-5 mg/kg, three injections per day for 1, 2, 4 or 6 days). The magnitude and duration of threshold elevations were proportional to the duration and dose of amphetamine treatment prior to withdrawal. In contrast, no alterations in ICSS thresholds were associated with withdrawal from chronic fluoxetine treatment (5 mg/kg/day for 15 days). While neither acute nor chronic administration of fluoxetine alone altered ICSS thresholds, chronic pretreatment with fluoxetine blocked the threshold-lowering effect of acute amphetamine administration (4 mg/kg), but acute pretreatment did not. Amphetamine-induced decreases in response latency, a measure of motor performance, were not affected by either chronic or acute fluoxetine pretreatment. CONCLUSIONS: The results of these experiments suggest that chronic fluoxetine treatment may induce adaptive changes in serotonergic transmission that, in themselves, do not alter the function of central reward processes, but may alter the ability of amphetamine to potentiate ICSS reward. In addition, the lack of change in ICSS thresholds during withdrawal from the chronic fluoxetine treatment regimen used suggests that withdrawal from all mood-altering drugs may not necessarily produce changes in central reward functions.

Amphetamine↗
PubMed1999

On the use of survival analysis techniques to estimate medical care costs.

Measurement of treatment costs is important in the evaluation of medical interventions. Accurate cost estimation is problematic, when cost records are incomplete. Methods from the survival analysis literature have been proposed for estimating costs using available data. In this article, we clarify assumptions necessary for validity of these techniques. We demonstrate how assumptions needed for valid survival analysis may be violated when these methods are applied to cost estimation. Our observations are confirmed through simulations and empirical data analysis. We conclude that survival analysis approaches are not generally appropriate for the analysis of medical costs and review several valid alternatives.

Costs and Cost Analysis↗
PubMed1999

The protein data bank. Bridging the gap between the sequence and 3D structure world.

The protein data bank (PDB), at Brookhaven National Laboratory, is a database containing information on experimentally determined three-dimensional structures of proteins, nucleic acids, and other biological macromolecules, with approximately 9000 entries. The PDB has a 27-year history of service to a global community of researchers, educators, and students in a wide variety of scientific disciplines. Data are easily submitted via PDB's WWW-based tool AutoDep, in either PDB or mmCIF format, and are most conveniently examined via PDB's WWW-based tool 3DB Browser. Collaborative centers have been, and continue to be, established worldwide to assist in data deposition, archiving, and distribution.

Databases, Factual↗
PubMed1999

Structural genomics: beyond the human genome project.

With access to whole genome sequences for various organisms and imminent completion of the Human Genome Project, the entire process of discovery in molecular and cellular biology is poised to change. Massively parallel measurement strategies promise to revolutionize how we study and ultimately understand the complex biochemical circuitry responsible for controlling normal development, physiologic homeostasis and disease processes. This information explosion is also providing the foundation for an important new initiative in structural biology. We are about to embark on a program of high-throughput X-ray crystallography aimed at developing a comprehensive mechanistic understanding of normal and abnormal human and microbial physiology at the molecular level. We present the rationale for creation of a structural genomics initiative, recount the efforts of ongoing structural genomics pilot studies, and detail the lofty goals, technical challenges and pitfalls facing structural biologists.

Computational Biology↗
PubMed1999

Assessment and control for confounding by indication in observational studies.

In the evaluation of pharmacologic therapies, the controlled clinical trial is the preferred design. When clinical trial results are not available, the alternative designs are observational epidemiologic studies. A traditional concern about the validity of findings from epidemiologic studies is the possibility of bias from uncontrolled confounding. In studies of pharmacologic therapies, confounding by indication may arise when a drug treatment serves as a marker for a clinical characteristic or medical condition that triggers the use of the treatment and that, at the same time, increases the risk of the outcome under study. Confounding by indication is not conceptually different from confounding by other factors, and the approaches to detect and control for confounding--matching, stratification, restriction, and multivariate adjustment--are the same. Even after adjustment for known risk factors, residual confounding may occur because of measurement error or unmeasured or unknown risk factors. Although residual confounding is difficult to exclude in observational studies, there are limits to what this "unknown" confounding can explain. The degree of confounding depends on the prevalence of the putative confounding factor, the level of its association with the disease, and the level of its association with the exposure. For example, a confounding factor with a prevalence of 20% would have to increase the relative odds of both outcome and exposure by factors of 4 to 5 before the relative risk of 1.57 would be reduced to 1.00. Observational studies have provided important scientific evidence about the risks associated with several risk factors, including drug therapies, and they are often the only option for assessing safety. Understanding the methods to detect and control for confounding makes it possible to assess the plausibility of claims that confounding is an alternative explanation for the findings of particular studies.

Antihypertensive Agents↗
PubMed1999

Initial clinical experience with a fully automatic in-hospital external cardioverter defibrillator.

Sudden cardiac death due to ventricular tachyarrhythmia remains a significant problem in the in-hospital setting. Although the probability of survival is closely correlated with the rapidity of a response by qualified personnel, response times can be prolonged, even in specialized care units. In an effort to decrease response time, a fully automatic external cardioverter defibrillator was recently devised. This device was evaluated in the in-hospital setting to assess safety and efficacy. A total of 79 patients were studied in a multicenter trial. Patients were monitored with fully functional devices in the electrophysiology laboratory (51 patients) and in the cardiac care unit (28 patients). Performance of the device was assessed by comparing automatic responses to any sustained change in cardiac rhythm, either spontaneous or induced, to a retrospective review of stored ECG data and programmed parameters. During a total duration of 964 hours of monitoring, there were 99 episodes of sustained tachycardia. Therapy was appropriately delivered or advised in all episodes. Therapy was advised in one episode of supraventricular tachycardia. There were no episodes of inappropriate therapy delivery. There were no complications or adverse events. The device performed with a sensitivity of 100% and specificity of 98.8% with an average response time of 22 seconds. In conclusion, this automatic external defibrillator was safe, effective, and functioned as designed. Significant improvement in response time to life-threatening ventricular tachyarrhythmia in the in-hospital setting would be expected if this technology was widely adopted.

Adult↗
PubMed1999

Cux/CDP homeoprotein is a component of NF-muNR and represses the immunoglobulin heavy chain intronic enhancer by antagonizing the bright transcription activator.

Nuclear matrix attachment regions (MARs) flanking the immunoglobulin heavy chain intronic enhancer (Emu) are the targets of the negative regulator, NF-muNR, found in non-B and early pre-B cells. Expression library screening with NF-muNR binding sites yielded a cDNA clone encoding an alternatively spliced form of the Cux/CDP homeodomain protein. Cux/CDP fulfills criteria required for NF-muNR identity. It is expressed in non-B and early pre-B cells but not mature B cells. It binds to NF-muNR binding sites within Emu with appropriate differential affinities. Antiserum specific for Cux/CDP recognizes a polypeptide of the predicted size in affinity-purified NF-muNR preparations and binds NF-muNR complexed with DNA. Cotransfection with Cux/CDP represses the activity of Emu via the MAR sequences in both B and non-B cells. Cux/CDP antagonizes the effects of the Bright transcription activator at both the DNA binding and functional levels. We propose that Cux/CDP regulates cell-type-restricted, differentiation stage-specific Emu enhancer activity by interfering with the function of nuclear matrix-bound transcription activators.

Animals↗
PubMed1999

Localization of sympathetic, parasympathetic and sensory neurons innervating the heart of the Beijing duck by means of the retrograde transport of horseradish peroxidase.

Sympathetic, parasympathetic and sensory neurons were labeled by injections of horseradish peroxidase into various regions of the heart in 33 Beijing ducks. Sympathetic postganglionic neurons innervating the heart were located in the paravertebral ganglia C15 (C16 is the last cervical segment in the duck) to T3, especially in the ganglion T1. The coronary sulcus and ventricle were more abundantly innervated by sympathetic neurons than the atrium. The left side of the heart was preferentially innervated by sympathetic postganglionic neurons in the left side of paravertebral ganglia but the right side of the heart were equally supplied from the right and left ganglia. Within the medulla oblongata, the number of labeled vagal preganglionic neurons in the nucleus ambiguus was much greater than that in the dorsal motor nucleus of the vagus nerve. Labeled neurons of the nucleus ambiguus were found in many ducks injected into the coronary sulcus. Cardiac sensory neurons were observed in the dorsal root ganglia C15 to T2 (highest in the ganglion T1) and in the nodose and jugular ganglia of the vagus nerve. These labeled neurons probably form the afferent and efferent limbs of cardiac reflexes and control circulation in the Beijing duck.

Animals↗