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Biomedical subjects

J Cheng

Publications and source records attributed to J Cheng.

At least 73 records · Page 4Linked to original sources
PubMed2001

Elevated white blood cell count and carotid plaque thickness : the northern manhattan stroke study.

BACKGROUND AND PURPOSE: Elevated leukocyte count has been associated with cardiovascular and cerebrovascular disease in several epidemiological studies. We sought to determine whether white blood cell count (WBC) is associated with carotid plaque thickness in a stroke-free, multiethnic cohort. METHODS: For this cross-sectional analysis, WBC was measured in stroke-free community subjects undergoing carotid duplex Doppler ultrasound. Maximal internal carotid plaque thickness (MICPT) was measured for each subject. Demographic and potential medical confounding factors were analyzed with linear and logistic regression to calculate the effect of quartile of WBC on MICPT. Odds ratios (ORs) and 95% confidence intervals (CIs) for the effect of quartile of WBC on MICPT >/=75th percentile were calculated. All analyses were stratified by race-ethnicity. RESULTS: The mean age of the 1422 subjects was 68.6+/-10.2 years; 40.0% were men; 24.4% were white, 46.9% Hispanic, and 26.7% black. Among Hispanics, compared with the lowest quartile of WBC, those in the highest quartile had significantly increased MICPT (mean difference=0.30 mm, P:=0.0086) after adjustment for age, sex, and other atherosclerotic risk factors. There was no significant increase for blacks or whites. The OR for MICPT >/=75th percentile (1.9 mm) was significantly increased for Hispanics (OR, 2.8; 95% CI, 1.4 to 5.6), marginally elevated for black non-Hispanics (OR, 1.6; 95% CI, 0.8 to 3.2), and not increased for white non-Hispanics (OR, 0.5; 95% CI, 0.2 to 1.1). CONCLUSIONS: Relative elevation in WBC is associated with carotid atherosclerosis, but this relationship differs by race-ethnicity. The association is strongest in Hispanics, intermediate in black non-Hispanics, and not present in white non-Hispanics in this population. Chronic subclinical infection or inflammation may account for this association.

Adult↗
PubMed2001

A PDZ-binding motif is essential but not sufficient to localize the C terminus of CFTR to the apical membrane.

Localization of ion channels and transporters to the correct membrane of polarized epithelia is important for vectorial ion movement. Prior studies have shown that the cytoplasmic carboxyl terminus of the cystic fibrosis transmembrane conductance regulator (CFTR) is involved in the apical localization of this protein. Here we show that the C-terminal tail alone, or when fused to the green fluorescent protein (GFP), can localize to the apical plasma membrane, despite the absence of transmembrane domains. Co-expression of the C terminus with full-length CFTR results in redistribution of CFTR from apical to basolateral membranes, indicating that both proteins interact with the same target at the apical membrane. Amino acid substitution and deletion analysis confirms the importance of a PDZ-binding motif D-T-R-L> for apical localization. However, two other C-terminal regions, encompassing amino acids 1370-1394 and 1404-1425 of human CFTR, are also required for localizing to the apical plasma membrane. Based on these results, we propose a model of polarized distribution of CFTR, which includes a mechanism of selective retention of this protein in the apical plasma membrane and stresses the requirement for other C-terminal sequences in addition to a PDZ-binding motif.

Amino Acid Motifs↗
PubMed2001

Diffraction tomography reconstruction algorithms for quantitative imaging of phase objects.

A new reconstruction algorithm for phase-object imaging is proposed that is based on the principle of diffraction tomography and utilizes the Fourier transformation property of a finite-size phase object. From the measured scattered intensity, the imaginary part of the Fourier transform of the object can be extracted, and the three-dimensional structure of the object can be reconstructed. Numerical simulations show that the algorithm also can be used for a weak absorption object if the phase shift is much larger than the absorption.

Algorithms↗
PubMed2001

Idiopathic hemochromatosis with the mutation of Ala176Val heterozygous for HFE gene.

Most patients with hereditary hemochromatosis are homozygous for C282Y in the HFE gene in populations of Celtic origin, but the genetic cause of this disease is unknown in Japan because of its rarity. A 48-year-old Japanese patient was recently diagnosed with idiopathic hemochromatosis. Analysis of the entire coding region of the patient's HFE by RT-PCR showed a heterozygous nucleotide substitution at nucleotide 527 from C to T, which resulted in A176V amino acid substitution. Another mutation at nucleotide 942 from T to C was observed, but this was a nonsense mutation. C282Y and another mutation, H63D, were not found in the patient. The mutation may have a possible role on the cause of hemochromatosis in this Japanese case.

Alanine↗
PubMed2001

The effect of perceptual grouping on the mismatch negativity.

The mismatch negativity (MMN) was used as a probe to evaluate changes, with age, of transient auditory memory. Subjects were 16 young (M = 23 years) and 16 old (M = 72 years) people. Standard auditory stimuli were presented in trains of eight tones (1000 Hz) with either a I-s or 8-s intertrain interval (ITI). Occasionally, the first stimulus of a train was replaced with a 1200 Hz tone (deviant). The MMN was recorded while subjects watched a silent movie and ignored the sounds. Both groups of subjects showed an MMN response to deviant stimuli under the 1-s ITI condition, but MMNs were only seen for some subjects under the 8-s ITI condition. After MMN recording, subjects performed a discrimination task to the tones used for recording MMNs. Accuracy for both groups was near 100% at both ITIs. These results suggest that generation of MMN is a function of the perceptual grouping of the acoustical stimuli and that the integrity of perceptual grouping may be maintained with increased age.

Adult↗
PubMed2001

[Cloning and sequence analysis of a pseudogene of liver regeneration augmenter in rats].

OBJECTIVE: To investigate the status of the augmenter of liver regeneration (ALR) in rat's genome. METHODS: Polymerase chain reaction (PCR) was used to amplify the genomic DNA of rat, with a set of specific primers designed according to the cDNA sequence of ALR. The products were ligated into pGEM Teasy vector. Two positive clones were sequenced separately. RESULTS: Two products were amplified from the rat's genome by PCR. After sequencing, one pseudogene was identified. The homology of the amino acid sequence between the ALR and its pseudogene was 88.8%. CONCLUSIONS: ALR pseudogene is found in rat's genome, implying that there is an ALR multigene family. This finding lays a foundation for further study of ALR molecular evolution mode.

Amino Acid Sequence↗
PubMed2001

[Cloning and sequence analysis of truncated S gene from circulation of patients with chronic hepatitis B virus infection].

OBJECTIVE: To find different mutated status of HBV DNA in circulation from chronic HBV patients. METHODS: Specially designed primers and polymerase chain reaction method were applied to amplify the whole S gene of HBV from the serum of 2 patients. After being sequenced, 4 clones were compared with HBV adr subtype (China strain) to identify the mutant sites. RESULTS: Sequencing results implied that there was a truncated large/middle S gene in the serum of the patients. Besides that, HBsAg and HBV DNA polymerase defective clones were also detected. CONCLUSIONS: Truncated middle S gene is found in the circulation of patients with chronical HBV infection, suggestive of a poor prognosis.

Cloning, Molecular↗
PubMed2001

[The quantitative analysis of voice disease based on fractal method].

The fractal method is employed to check the voice diseases. The severity of pathological changes of human voice can be analyzed objectively and quantitatively with different fractal dimensions. With this method we can end up the history of judging the voice with subjective hearing and it is of great importance to the development of laryngology.

Fractals↗
PubMed2001

Polymorphic markers in the SRD5A2 gene and prostate cancer risk: a population-based case-control study.

It has been suggested that the activity of the steroid 5alpha-reductase type II enzyme (encoded by the SRD5A2 gene) may be associated with prostate cancer risk and that population differences in this enzyme's activity may account for part of the substantial racial/ethnic disparity in prostate cancer risk. To provide etiological clues, we evaluated the relationships of four polymorphic markers in the SRD5A2 gene, specifically, A49T (a substitution of threonine for alanine at codon 49), V89L (a substitution of leucine for valine at codon 89), R227Q (a substitution of glutamine for arginine at codon 227), and a (TA)n dinucleotide repeat, with prostate cancer risk in a population-based case-control study in China, a population with the lowest reported prostate cancer incidence rate in the world. Genotypes of these four markers were determined from genomic DNA of 191 incident cases of prostate cancer and 304 healthy controls using PCR-based assays, and serum androgen levels were measured in relation to these genotypes. All study subjects had the wild-type AA genotype of the A49T marker, and 99% had the RR genotype of the R227Q marker. For the V89L marker, prevalences of the LL, VV, and VL genotypes among controls were 35%, 21%, and 45%, respectively. Compared with men with the VV genotype, those with the LL genotype had a statistically nonsignificant 12% reduced risk (odds ratio = 0.88, 95% confidence interval, 0.53-1.47). In addition, men with the LL genotype had significantly higher serum levels of testosterone and significantly lower serum levels of 5alpha-androstane-3alpha,17beta-diol glucuronide than men with other genotypes. Men heterozygous for the (TA)0 allele of the (TA)n marker had a modest, statistically nonsignificant risk reduction (odds ratio = 0.67; 95% confidence interval, 0.39-1.12) compared with men homozygous for the (TA)0 allele, along with significantly higher serum dihydrotestosterone levels. The observed V89L genotype prevalences and the association between V89L genotypes and serum androgen levels support the hypothesis that genotypes associated with lower levels of 5alpha-reductase activity are more common in low-risk populations. Although we found no statistically significant associations of these SRD5A2 polymorphisms with prostate cancer risk, a small effect of these markers cannot be ruled out because of the rarity of certain marker genotypes. Larger studies are needed to further clarify the role of these markers and to elucidate whether genetic diversity of the SRD5A2 gene, alone or in combination with other susceptibility genes, can help explain the large racial/ethnic differences in prostate cancer risk.

Adult↗
PubMed2001

[Screening and characterization of human phage antibody to hepatitis C core antigen].

OBJECTIVE: To screen and characterize human phage antibody (ScFv) against hepatitis C core antigen. METHODS: The recombinant phages were panned by core antigen that was coated in a microtiter plate. After three rounds of biopanning, 48 clones were determined specific to core antigen. The specificity of each ScFv colone was determined by ELISA. The coding gene for HCV protein ScFv has been sequenced. RESULTS: Phage antibody for HCV core protein had a specific combination character with core antigen of hepatitis C virus. The DNA sequence data showed that the ScFv gene included 774 bp. CONCLUSIONS: Human single chain antibody to hepatitis C core antigen has been identified by means of the phage display technology.

Amino Acid Sequence↗
PubMed2001

[The language healing system of deaf children based on wavelet transform].

In the language healing system of deaf children, the wavelet transform method is employed to describe the time-varying characteristics of speech signals, improve the resolution of speech spectrum and make the speech characteristics more obvious. The speech spectrum information shown in this system is easier for deaf children to observe and understand and it is of great importance to the language healing of deaf children.

Child↗
PubMed2001

[The complexity measure and its application to EEG analysis].

In this paper are reviewed the conceptions, characteristics and application of the complexity measure in studying EEG. The reviewers expound the advantages and problems of using complexity measure in the analysis of EEG in different physiological states and deem it a new way to study and understand the human brain function.

Algorithms↗
PubMed2001

[Study on weekly low doses of mifepristone for contraception].

OBJECTIVE: To study whether weekly low dose of mifepristone (5 mg or 10 mg) is sufficient to prevent pregnancy. METHODS: Thirty-nine women were randomly allocated to take mifepristone 5 mg (group A) or 10 mg (group B) doses once weekly starting on cycle day 2-3. The serum levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were determined by enzymeimmunoassay (EIA), and estradiol (E2) and progesterone (P) levels by radioimmunassay (RIA). Serum mifepristone concentrations were measured by high performance liquid chromatography (HPLC). Morphometric analyses and progesterone receptor (PR), Dolichus biflorus agglutinin (DBA-lectin) and integrin alpha v beta 3 of endometrium were also measured. RESULTS: There were 4 pregnancies out of 64 cycles in group A, and 3 out of 68 cycles in group B. Normal LH and FSH peak could be detected in the first treatment cycles, LH peak appeared on 15-17 d. The concentrations of P were (51.93 +/- 7.91) nmol/lL and (69.00 +/- 21.29) nmol/L in group A and B respectively. The average level of E2 was (407.81 +/- 89.27) pmol/L in group A, and (557.85 +/- 204.69) pmol/L in group B. Serum mifepristone level could be detected within 36 hours. The PR concentration in endometrium decreased significantly, but not of DBA-lectin, integrin alpha v beta 3. CONCLUSIONS: Administration of mifepristone 5 mg or 10 mg once weekly does not inhibit ovulation completely. The follicular phase prolonged slightly, and E2 levels were low following treatment. The endometrium showed delayed development. The clinical contraceptive effectiveness needs to be improved.

Adult↗
PubMed2001

Modeling of organic pollutant destruction in a stirred-tank reactor by ozonation.

Destruction of organic contaminants in water by ozonation is a gas-liquid process which involves ozone mass transfer and fast irreversible chemical reactions. Ozonation reactor design and process optimizing require the modeling of the gas-liquid interactions within the reactor. In this paper a theoretical model combining the fluid dynamic and reaction kinetic parameters is proposed for predicting the destruction rates of organic pollutants in a semi-batch stirred-tank reactor by ozonation. A simple expression for the enhancement factor as our previous work has been applied to evaluate the chemical mass transfer coefficient in ozone absorption, 2,4-dichlorophenol (2,4-DCP) and 2,6-DCP or their mixture are chosen as the model compounds for simulating, and the predicted DCP concentrations are compared with some measured data.

Absorption↗