Biomedical subjects

Z M Zhang

Publications and source records attributed to Z M Zhang.

At least 19 recordsLinked to original sources

PubMed2006

QTL mapping analysis of plant height and ear height of maize (Zea mays L.).

Genetic map containing 103 microsatellite loci obtained on 200 F2 plants derived from the cross R15 x 478 was used for quantitative trait loci (QTL) mapping in maize. QTL were characterized in a population of 200 F2:4 lines, derived from selfing the F2 plants, and were evaluated with two replications in two environments. QTL determinations were made from the mean of these two environments. Plant height (PH) and ear height (EH) were measured. Using composite interval mapping (CIM) method, a total of 14 distinct QTLs were identified: nine for PH and five for EH. Additive, partial dominance, dominance, and overdominance actions existed among all detected QTL affecting plant height and ear height. The QTL explained 78.27% of the phenotypic variance of PH and 41.50% of EH. The 14 QTLs displayed mostly dominance or partial dominance gene action and mapped to chromosomes 2, 3, 4, 8 and 9.

Chromosome Mapping↗

PubMed2005

Planar heterogeneous structures for coherent emission of radiation.

The coupling of excited surface polaritons with thermal radiation through diffraction by gratings results in coherent thermal emission in a certain frequency range toward well-defined directions for p polarization. A planar coherent source is proposed that uses multilayers of negative permittivity (epsilon) and negative permeability (mu) materials. Owing to the excitation of surface polaritons at the interface between the negative-epsilon and negative-mu layers, coherent emission can be achieved for both s and p polarization. Moreover, one can control the emission frequency and direction by adjusting the layer thicknesses.

Journal Article↗

PubMed2003

Fresnel representation of the Wigner function: an operational approach.

We present an operational definition of the Wigner function. Our method relies on the Fresnel transform of measured Rabi oscillations and applies to motional states of trapped atoms as well as to field states in cavities. We illustrate this technique using data from recent experiments in ion traps [Phys. Rev. Lett. 76, 1796 (1996)]] and in cavity QED [Nature (London) 403, 743 (2000)]]. The values of the Wigner functions of the underlying states at the origin of phase space are W(|0>)(0)=+1.75 for the vibrational ground state and W(|1>)(0)=-1.4 for the one-photon number state. We generalize this method to wave packets in arbitrary potentials.

Journal Article↗

PubMed2001

Usefulness of T-axis deviation as an independent risk indicator for incident cardiac events in older men and women free from coronary heart disease (the Cardiovascular Health Study).

T-axis shift has been reported to be an indicator of increased mortality risk. We evaluated the association of spatial T-axis deviation with incident coronary heart disease (CHD) events in older men and women free from clinically overt CHD. Spatial T-axis deviation was measured from the standard 12-lead electrocardiogram of a subgroup of 4,173 subjects considered free of CHD at baseline in the Cardiovascular Health Study, a prospective cohort study of risk factors for CHD and stroke in older men and women. Cox regression analysis was used to evaluate the association of altered repolarization with the risk of incident CHD events. The prevalence of marked T-axis deviation (> or =45 degrees ) was 12%. During the median follow-up of 7.4 years, there were 161 CHD deaths, 743 deaths from all causes, and 679 incident CHD events. Adjusting for demographic and clinical risk factors, including other electrocardiographic abnormalities, there was a nearly twofold excess risk of CHD death, and approximately a 50% excess risk of incident CHD and all-cause mortality for those with marked T-axis deviation. From other electrocardiographic abnormalities, only QT prolongation was associated with excess risk for incident CHD comparable to that for abnormal T-axis deviation. These results suggest that T-axis deviation is an easily quantified marker for subclinical disease and an independent indicator for the risk of incident CHD events in older men and women free of CHD.

Aged↗

PubMed2001

Acquisition of secondary structural chromosomal changes in pediatric ewing sarcoma is a probable prognostic factor for tumor response and clinical outcome.

BACKGROUND: The Ewing sarcoma (ES) group of tumors commonly have the t(11;22)(q24;q12) or other rearrangements involving 22q12. In addition to these consistent aberrations, both numeric and structural aberrations have been reported: namely gains of chromosomes 8 and 12, the unbalanced translocation t(1;16), and deletions at the short arm of chromosome 1. METHODS: To evaluate the frequency and to study the prognostic implications of some of these aberrations in children, the authors performed a pilot study of 26 ES pediatric patients by classic cytogenetics and/or interphase fluorescence in situ hybridization (FISH) and compared these data with clinical parameters. RESULTS: Gains of chromosomes 8 and 12 were detected, by interphase FISH, in 48% (10 of 21) and 38% (6 of 16) of the tumors, respectively, and this was not significant with respect to treatment response. Statistical analysis revealed that the presence of additional secondary structural chromosomal aberrations was associated with an unfavorable outcome (P = 0.0034 as an independent prognostic value as an unfavorable marker). Presence of metastasis at diagnosis also was found to be associated with poor outcome (P = 0.0131). Spectral karyotyping analysis was shown to facilitate the detection of more complex structural chromosomal aberrations in a representative ES tumor. CONCLUSIONS: It is important to determine whether additional structural chromosomal aberrations are present in ES tumors because it appears that a more complex karyotype with multiple chromosomal aberrations is associated with poor outcome in ES.

Adolescent↗

PubMed2001

Spectrofluorimetric determination of thiols by use of N[P-(2-benzoxazolyl)phenyl]maleimide.

The weak fluorescence of N-[P-(2-benzoxazolyl)phenyl]maleimide (BOPM) can be greatly enhanced by thiol-containing compounds. A sensitive and simple spectrofluorimetric method based on the use of BOPM has been developed for the determination of thiols such as cysteine (Cys) and reduced glutathione (GSH). Calibration plots were linear in the concentration range from 0 to 1.6 x 10(-7) mol L(-1) for Cys and 0 to 1.7 x 10(-7) mol L(-1) for GSH. The detection limits (3a) were 2.36 x 10(-10) mol L(-1) for Cys and 1.49 x 10(-10) mol L(-1) for GSH. Many other amino acids (present at 100-fold greater concentrations) did not interfere with the determination. The proposed method has been used for the determination of Cys in protein hydrolysate and cystine electrolyte or GSH in serum, with recoveries of 95.4-103.7%.

Journal Article↗

PubMed2000

Alterations of H19 imprinting and IGF2 replication timing are infrequent in Beckwith-Wiedemann syndrome.

Beckwith-Wiedemann syndrome (BWS) is an overgrowth disorder resulting from dysregulation of multiple imprinted genes through a variety of distinct mechanisms. A frequent alteration in BWS involves changes in the imprinting status of the coordinately regulated IGF2 and H19 genes on 11p15. Patients have been categorized according to alterations in the imprinted expression, allele-specific methylation, and regional replication timing of these genes. In this work, IGF2/H19 expression, H19 DNA methylation, and IGF2 regional replication timing were studied in nine karyotypically normal BWS fibroblasts and two BWS patients with maternally inherited 11p15 chromosomal rearrangements. Informative patients (9/9) maintained normal monoallelic H19 expression/methylation, despite biallelic IGF2 expression in 6/9. Replication timing studies revealed no changes in the pattern of asynchronous replication timing for both a patient with biallelic IGF2 expression and a patient carrying an 11p15 inversion. In contrast, a patient with a chromosome 11;22 translocation and normal H19 expression/methylation exhibited partial loss of asynchrony and a shift toward earlier replication times. These results indicate that in BWS, (1) H19 imprinting alterations are less frequent than previously estimated, (2) IGF2 imprinting and H19 imprinting are not necessarily coordinated, and (3) alterations in regional replication timing are generally not correlated with either chromosomal rearrangements or the imprinting status of IGF2 and H19.

Beckwith-Wiedemann Syndrome↗

PubMed2000

Telomerase activity in Papanicolaou smear-negative exfoliated cervical cells and its association with lesions and oncogenic human papillomaviruses.

OBJECTIVE: The goal of this study was to evaluate telomerase activity in exfoliated cervical cells and its association with cytology, pathology, and human papillomavirus (HPV). METHODS: Telomerase activity and HPV DNA sequences were examined in the exfoliated cervical cells from a general population of 245 women aged more than 30 years undergoing routine cervical screening by Papanicolaou smear. The women who were found to have telomerase activity or abnormal cytology in their exfoliated cervical cells were examined for cervical lesions by colposcopy and biopsy. RESULTS: Cytology for our population (mean, 56 years) revealed only one abnormal smear (1/245, 0.4%), in which a cervical intraepithelial neoplasia grade I (CIN I) lesion was found. The exfoliated cervical cells used to prepare the smear were negative for telomerase and contained low-risk HPV DNA. Telomerase activity was found in 16 exfoliated cell samples (16/245, 6.5%); high-risk HPV DNA was found in 9 of these samples (9/16, 56%) and 9 of the biopsy specimens that could be evaluated from patients testing positive for telomerase revealed CIN I lesions (9/11, 82%). CONCLUSIONS: Telomerase activity is often associated with high-risk HPV infection and it is suggested that telomerase assay can help to detect occult cervical lesions.

Adult↗

PubMed2000

[Change of Fo and vocal range of pathological voice].

OBJECTIVE: To study the relationship between Fo and true or falsetto range in four phonation modes. METHOD: Testing Fo of lowest true voice, comfortable voice, highest true voice and falsetto voice. RESULT: In pathological voice, Fo of lowest true voice increases, Fo of highest falsetto voice reduces, true and falsetto voice range become thin and the change of falsetto voice range is more obvious. CONCLUSION: Fo of falsetto highest voice reduces, falsetto voice rang become thin in pathological voice.

Adolescent↗

PubMed1999

Chromosomal localization of phospholipase A2 activating protein, an Ets2 target gene, to 9p21.

A murine Ets2 target gene isolated by differential display cloning was identified as the phospholipase A2 activating protein (PLAA) gene. A 2.7-kb human cDNA demonstrating high homology to mouse and rat Plaa genes was then isolated and characterized. Human PLAA contains six WD-40 repeat motifs and three different protein kinase consensus domains. Fluorescence in situ hybridization (FISH) mapping placed PLAA on chromosome 9p21, a region frequently deleted in various cancers. A comprehensive mapping strategy was employed to define further the chromosomal localization of PLAA relative to CDKN2A within the 9p21 locus. Radiation hybrid mapping placed the gene 7.69 cR from WI-5735 (LOD >3.0), a marker in close proximity to CDKN2A and CDKN2B. Yeast artificial chromosome (YAC) mapping localized PLAA proximal to the CDKN2A/CDKN2B genes and to a region flanked by D9S171 and INFA commonly deleted in many neoplasms. Two YACs contained both PLAA and D9S259, a marker present in a second more proximal minimal deleted region observed in cutaneous melanoma and squamous cell lung carcinoma. Double-color fiber FISH mapping confirmed the location of PLAA centromeric to D9S171 and CDKN2A/CDKN2B. The mapping data suggest a possible tumor suppressor role for this gene.

Animals↗

PubMed1999

Characterization of Astragalus sinicus rhizobia by restriction fragment length polymorphism analysis of chromosomal and nodulation genes regions.

Two hundred and four isolates of rhizobia were sampled from root nodules of Astragalus sinicus grown in rice fields of six southern provinces of China. Genotypic diversity was determined by Southern hybridization using nodDBC genes as a probe, restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S-23S rDNA intergenic spacers (IGS), and plasmid profile. Our results show that rhizobia associated with A. sinicus were very diverse, and 10 genotypes were resolved within the previously identified dominant 16S rDNA type. Diversity levels varied greatly between different geographical locations. The same nod gene genotypes were harbored by distinct chromosomal types, suggesting that lateral plasmid transfer occurred during the evolution process.

Blotting, Southern↗

PubMed1999

Hemangioendothelioma of bone in a patient with a constitutional supernumerary marker.

A 13-year old girl was diagnosed as having a bone hemangioendothelioma. Cytogenetic studies identified the presence of a small supernumerary marker chromosome in this patient. Classical cytogenetic methods using G-, C-, Ag-NOR-banding were supplemented by spectral karyotyping (SKY) and fluorescence in situ hybridization to reveal a karyotype 47,XX,+mar.ish der(22)(D22S543+) karyotype in cells derived from the tumor and lymphocytes. These findings suggest that the supernumerary marker chromosome originated from the proximal centromeric region of chromosome 22, and that trisomy of the region 22q11 was not associated with adverse phenotypic effects, but that the presence of trisomy 22q11 may be related to the development of this tumor.

Adolescent↗

PubMed1999

[Effects of glutamate on transient outward potassium current of dissociated hippocampal neurons in ca1 sector in rats].

The effects of glutamate on the transient outward potassium current of dissociated hippocampal CA(1) neurons of 7-10 d rats were studied by the whole-cell patch clamp technique. It was found that glutamate could block the transient potassium current in a dose- and time-dependent manner. The effect was partly voltage-dependent. These results suggest that glutamate may decrease the membrane conductance of K(+) channels in hippocampal neurons.

Animals↗

PubMed1998

The Novacode criteria for classification of ECG abnormalities and their clinically significant progression and regression.

Electrocardiographic (ECG) manifestations of clinical and subclinical cardiovascular disease are used as an important component in the evaluation of clinical trials, and there is an increasing demand for well-defined criteria for clinically significant evolution of ECG abnormalities. The Novacode ECG classification system provides a comprehensive hierarchical set of criteria for prevalent ECG abnormalities and for clinically significant serial ECG changes, both adverse and favorable, as a response to pharmacologic, surgical, and other interventions. These criteria are used to grade Q wave and ischemic abnormalities in order to achieve stable classification of both prevalent and incident myocardial infarctions by minimizing false classifications due to clinically insignificant ECG variations. This approach differs from the traditional Minnesota Code classification system, in which incident events are determined by changes in classification categories, with the application of additional elaborate validation rules to exclude frequent false classifications. Novacode hierarchy is so structured that for each abnormality, a general class is first determined with the simplest possible classification criteria and more specific abnormality subgroups are then classified with more elaborate criteria. This approach will satisfy differing needs of clinical trials for detail in classification. Explicit definition of ECG variables and condition statements for the classification criteria facilitate implementation of the Novacode with computer ECG programs.

Arrhythmias, Cardiac↗

PubMed1997

Nutrition and other risk factors for renal cell carcinoma in postmenopausal women.

Among 35,192 postmenopausal, predominantly white women in Iowa age 55-69 years and free of cancer, we collected baseline history, dietary information, and anthropometric data by mail in 1986. We ascertained the 8-year incidence (62 new cases) of renal cell carcinoma using the Iowa Surveillance, Epidemiology, and End Results (SEER) register, the National Death Index, and mail follow-up. Risk factors for renal cell carcinoma included increasing age, increasing weight (either current, maximum adult weight, or weight at ages 18, 30, or 50 years), greater waist-to-hip ratio, and a history of blood transfusion. Total dietary calcium was associated independently with a reduced risk of renal cell carcinoma. No other dietary micro- or macronutrients or food groups were predictive of the development of renal cell carcinoma. Other previously identified risk factors were not confirmed: most notably, there was no increased risk from a history of hypertension, after adjustment for diuretic use. History of ever-use of diuretics was associated with a twofold increased risk of renal cancer, although the strength of association was markedly reduced after adjustment for age, weight, waist-to-hip ratio, and calcium intake.

Adult↗

PubMed1997

Antioxidative activity of 4-oxy- and 4-hydroxy-nitroxides in tissues and erythrocytes from rats.

AIM: To compare the activities of antioxidation of 4-oxy- and 4-hydroxy-nitroxides in tissues and RBC from rats. METHODS: The homogenates of liver, heart, and kidneys of rats were used to determine malondialdehyde (MDA) formation using TBA colorimetric method. H2O2-caused hemolysis was measured spectrometrically. Superoxide anion from zymosan-stimulated neutrophils of rats was assayed by NBT reduction method. RESULTS: Nitroxide free radicals OTMPO and HTMPO inhibited MDA generation caused by .OH generation system (MIC 10.5 and 21 mumol.L-1, respectively), antagonized hemolysis induced by H2O2 (MIC: 338 and 168 mumol.L-1, respectively), but did not affect O2- formation from activated neutrophils. 1-Hydroxyl compounds OTMPOH and HTMPOH possessed similarly potent antilipoperoxidative activities. But nonfree radical OTMP and HTMP had no effect on peroxidation of tissues. CONCLUSION: Nitroxides exert their antilipoperoxidative effect by specifically scavenging .OH free radicals in biological system. Trapping of .OH free radicals by nitroxides is not by reduction of NO. group in nitroxides. Both NO. group and NOH group are essential active groups.

Animals↗

PubMed1996

Effects of valve substitute on changes in left ventricular function and hypertrophy after aortic valve replacement.

BACKGROUND: Residual left ventricular hypertrophy adversely affects long-term outcome after aortic valve replacement. A stentless biological valve in the aortic position has been shown to offer a better hemodynamic profile than a stented one. However, it remains to be defined whether this difference is translated into inter-mediate-term effects on left ventricular structure and function. METHODS: One hundred thirty-seven patients receiving single aortic valve replacement (52 with concomitant coronary artery bypass graft) were enrolled in this study. Ninety-eight were men, and the mean age was 68 years (range, 55 to 90 years). Of the 137 patients, 39 had an aortic homograft, 72 a Toronto stentless porcine valve, and 26 had a stented porcine or bileaflet mechanical valve, with mean valve size of 25 +/- 2.5 mm (mean +/- standard deviation). Left ventricular muscle mass and function were assessed by M-mode echocardiography performed before and 0.5, 6, 12, 24, and 36 months after operation, and recorded on paper for off-line digitizing. Peak valve prosthesis pressure gradients were quantified by continuous wave Doppler. RESULTS: A total of 330 echocardiograms obtained during this study were adequate for computer digitizing. Clinical data, preoperative left ventricular function, and hypertrophy were similar between the three groups. Significant improvement in left ventricular function and major regression of left ventricular hypertrophy had occurred in the entire population by 6 months after operation. Multivariate analysis of variance showed that patients with previous aortic regurgitation had a larger left ventricular cavity size (p < 0.001) and greater mass index (p = 0.001) postoperatively than those with previous aortic stenosis. In addition, peak valvular gradient was lower (p < 0.001), mass index less (p < 0.001), and left ventricular function more normal both systolic, by a greater peak velocity of dimension shortening (p = 0.05) and wall thickening (p = 0.002), and diastolic, by a greater peak velocity of dimension lengthening (p = 0.046), with an aortic homograft or stentless porcine valve compared with a mechanical or stented biological valve. There was no significant difference in peak valve gradient, left ventricular mass index, or function between the aortic homograft and the stentless porcine valve. Age, sex, and concomitant coronary artery bypass graft, as well as aortic cross-clamp time, cardioplegia method, and valve size all proved to be insignificant determinants of postoperative left ventricular hypertrophy or function. CONCLUSIONS: In the first 2 years after implantation, the superior hemodynamic performance of aortic homograft and stentless porcine valve appears to result in more extensive regression of ventricular hypertrophy and greater improvement of left ventricular function than occurs with a mechanical or stented biological valve. These findings encourage the use of a stentless biological valve in older patients requiring aortic valve replacement, and a larger scale long-term randomized study of stentless versus stented biological valve or mechanical valve seems warranted.

Aged↗

PubMed1995

[Clinical observation on child aplastic anemia treated with integrated Chinese and Western medicine].

Forty-three cases of aplastic anemia were treated with fetal blood transfusion, Chinese medicinal herbs and Vit. C. The results showed that the effective rate of the treated group was 79.1%, among them, the chronic aplastic anemia (CAA) was 88.9%, acute aplastic anemia (AAA) was 62.5%, both rates were higher than that of the control group (with western medicine alone, n = 46). The difference of treatment results between two groups was highly significant. The mechanism was that the therapy could rebuild hematopoietic function, modulate immune function and improve microcosmic environment in bone marrow so that it promoted in all aspect the recovery of hematopoietic function in organism.

Adolescent↗