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Biomedical subjects

W Zhu

Publications and source records attributed to W Zhu.

At least 235 records · Page 13Linked to original sources
PubMed1997

Bioelectrical activity of the central nervous system among populations in a rare earth element area.

Auditory brainstem electric response (ABR) and somatosensory evoked potential (SEP) of 21 subjects (41 ears) among villagers in a rare earth element (REE) area in Gan County, Jiangxi, China, were studied. No difference in ABR between the subjects from the REE area and the control group was noted. However, the conduction detected by SEP from the median nerve to the thalamus (P15) was shortened (P < 0.05), especially to the first-grade primary somatosensory responsive region (S1) (P < 0.01) and the amplitude of S1 decreased (P < 0.05), indicating that REE was difficult to accumulate in the brainstem, but it was susceptible to cerebral cortex, thus causing sub-clinical damage. This condition was confirmed in the animal experiment. It was suggested that the toxicity through long-term intake of small doses of REE might not be negligible, and the hazard of REE environments should be investigated.

Acetylcholinesterase↗
PubMed1997

Contraceptive practices of women requesting termination of pregnancy: a study from China.

In order to develop a program for prevention of unwanted pregnancies, we conducted a survey of contraceptive practices and reasons for contraceptive failures of 1520 women seeking abortion at eight large hospitals in Zheng Zhou City, Henan Province, P.R. China, during the period from March 1996 to May 1996. The most frequent cause of the unplanned pregnancy was contraceptive failure (71.9%) 61.7% (938) of these current pregnancies were potentially predictable by virtue of nonuse of contraception (427) or by recognition of contraceptive failures (511). Among the contraceptive failures, the proportion of condom mishaps was the highest (29.7%), next was IUD failures (23.5%), then rhythm miscalculation (15.9%). Most of abortion seekers (77.1%) used some contraceptive methods previously. But only 19.7% of them used a contraceptive method at the first sexual intercourse. Among 1520 abortion seekers. 57.6% had used condoms previously; 50.9% of the condom users had at least one instance of condom mishap. The rhythm method had been used by 31.7% of abortion seekers previously; 59.1% of the rhythm users had at least one instance of rhythm failure. Of the 16.8% of abortion seekers who had used pills, 58.0% of them had pill failures Among condom and pill failures, most of them (46.4% condom users and 56.0%, pill users) belonged to the users failure category (poor compliance). Of those seeking abortion 56.4% had experienced at least one instance of previous abortion; 5.3% had experienced previous abortions at least two times. Emergency contraception had been utilized by only 10 subjects prior to this current pregnancy.

Abortion, Induced↗
PubMed1997

Assessment of intraaxial and extraaxial brain lesions with digitized computed tomographic images versus film: ROC analysis.

RATIONALE AND OBJECTIVES: The authors evaluated the diagnostic accuracy of viewing computed tomographic (CT) scans as film versus soft-copy images at a workstation. METHODS: Receiver operating characteristic analysis of the interpretation of 202 CT scans (103 were normal, 99 were abnormal) by five neuroradiologists was performed. Abnormal images contained high- or low-attenuation intraaxial lesions or extraaxial fluid (subdural, subarachnoid, or epidural hemorrhage). Hard copies were read on a standard light box, and digital images were examined at a 1,024 x 1,250 workstation. Lesion location and type and confidence ratings were recorded on a worksheet. RESULTS: There were no statistically significant differences in diagnostic accuracy between the two display modes. Reader performance was slightly better with the workstation in the assessment of low-attenuation lesions. CONCLUSION: Diagnostic accuracy is similar for CT scans displayed at a workstation and those displayed as hard copy in the assessment of subtle intra- and extraaxial brain lesions.

Brain↗
PubMed1997

Enhanced hydrogen peroxide sensitivity and altered stress protein expression in iron-starved Mycobacterium smegmatis.

Mycobactericum smegmatis ATCC 607 became iron starved and did not reach maximum population density when grown at an iron concentration of 0.1 microM, or less. Iron deficient cells were more susceptible than iron replete cells to H2O2 killing; 9 mM H2O2 killed about 80% of the population of cultures grown at 0.05 microM iron, while about 25 mM H2O2 was required for similar killing of cultures grown at 1 or 20 microM iron. In response to H2O2, iron sufficient cells produced major oxidative stress proteins of molecular masses of 90, 75, 65, 62, and 43 kDa (the 75 and 65 kDa proteins were identified as DnaK and GroEL homologs, respectively). Iron deficient M. smegmatis did not upregulate the DnaK and GroEL proteins when stressed with H2O2. Both iron deficient and iron sufficient M. smegmatis produced (at 48 degrees C) major heat shock proteins of molecular masses of 90, 75 (DnaK), 65 (GroEL), 62, 43, and 16 kDa. The stress protein response induced by 2 M ethanol challenge was similar to the heat shock response except that ethanol induced a unique 55 kDa protein and the 16 kDa heat shock protein was not apparent. Induction of ethanol stress proteins was identical in high iron and low iron cells. All of the stress agents induced expression of a 62 kDa protein which may also be induced by iron insufficiency. The heat and ethanol shock responses of M. smegmatis were unchanged by iron deficiency; therefore, the absence of DnaK and GroEL from the response of iron starved M. smegmatis to H2O2 may be due to a specific defect (or alteration) of the oxidative stress response during iron starvation.

Amino Acid Sequence↗
PubMed1997

Regulation of gene expression for tyrosine hydroxylase in oxygen sensitive cells by hypoxia.

Carotid body type I cells and the O2 sensitive pheochromocytoma (PC12) cells release dopamine during hypoxia. Reduced O2 tension causes inhibition of an outward rectifying the O2-sensitive potassium (K) channel in the O2-sensitive pheochromocytoma (PC12) cell line, which leads to membrane depolarization and increased intracellular free Ca2+. We found that removal of Ca2+ from the extracellular milieu, inhibition of voltage-dependent Ca2+ channels, and chelation of intracellular Ca2+ prevents full activation of the TH gene expression during hypoxia. These findings suggest that membrane depolarization and regulation of intracellular free Ca2+ are critical signal transduction events that regulate expression of the TH gene in PC12 cells during hypoxia. Gene expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in the biosynthesis of dopamine, is stimulated by reduced O2 tension in both type I cells and PC12 cells. The increase in TH gene expression in PC12 cells during hypoxia is due to increases in both the rate of transcription and mRNA stability. Analysis of reporter-gene constructs revealed that increased transcription of the TH gene during hypoxia is regulated by a region of the proximal promoter that extends from -284 to -150 bases, relative to the transcription start site. This region of the gene contains a number of cis-acting regulatory elements including AP1, AP2 and hypoxia-inducible factor (HIF-1). Competition assays revealed that hypoxia-induced binding occurs at both the AP1 and HIF-1 sites. Results from super-shift and shift Western assays showed that a heterodimer consisting of c-Fos and JunB binds to the AP1 site during hypoxia. Mutagenesis experiments revealed that the AP1 site is required for increased transcription of the TH gene during hypoxia. We also found that the genes that encode the c-Fos and JunB transcription factor proteins are regulated by reduced O2 tension.

Animals↗
PubMed1997

A multilevel analysis of school factors associated with health-related fitness.

School factors associated with health-related fitness, using the National Children and Youth Fitness Survey II (NCYFS II) data, have been examined by Pate and Ross (1987), but the hierarchical structure of the data was ignored in the data analyses. The purpose of this study was to reanalyze the NCYFS II data using the hierarchical linear model and reexamine the effects of school physical education (PE) and other factors on children's 1-mile run/walk performance. Only two of five "significant" school factors were confirmed by this study, suggesting that heightened probabilities of Type I errors might have occurred in the previous study. Two confirmed key characteristics of school PE programs that led to improvement of children's cardiovascular endurance were PE specialists and the administration of fitness tests. For a hierarchical data structure, both experimental and observational units should be considered in the data analysis. The hierarchical linear model, which not only provides more accurate individual prediction but also takes group effect into account, proved to be an appropriate analytical model in analyzing the hierarchical data.

Age Factors↗
PubMed1997

Making bootstrap statistical inferences: a tutorial.

Bootstrapping is a computer-intensive statistical technique in which extensive computational procedures are heavily dependent on modern high-speed digital computers. The payoff for such intensive computations is freedom from two major limiting factors that have dominated classical statistical theory since its beginning: the assumption that the data conform to a bell-shaped curve, and the need to focus on statistical measures whose theoretical properties can be analysed mathematically. The name "bootstrap" was derived from an old saying about pulling oneself up by one's bootstraps. In this case, bootstrapping means redrawing samples randomly from the original sample with replacement. The key idea, computations, advantages, limitations, and application potential of bootstrapping in the field of physical education and exercise science are introduced and illustrated using a set of national physical fitness testing data. Finally, an example of a bootstrapping application is provided. Through a step-by-step approach, the development and implementation of the bootstrap statistical inference are illustrated.

Data Interpretation, Statistical↗
PubMed1997

Induction of interleukin-2 receptor alpha gene by delta9-tetrahydrocannabinol is mediated by nuclear factor kappaB and CB1 cannabinoid receptor.

Previously, we reported that the cannabinoid delta9-tetrahydrocannabinol (THC) increased the expression of interleukin-2 (IL-2) receptor (R) alpha and beta proteins and mRNAs in NKB61A2 cells, but decreased the level of the gamma-chain message. The drug increased beta-chain message stability rather than increased transcription. In the present study, we examined the mechanism responsible for the drug-induced increase in alpha-chain message in NKB61A2 cells. Nuclear run-on and mRNA stability studies showed THC increased the level of alpha gene transcription but had no effect on mRNA stability. Because expression of this gene is regulated by nuclear factor (NF)-kappaB, we next tested the drug effect on the nuclear level of this protein using the electromobility shift assay. These studies showed a drug-induced increase in NF-kappaB activity. To link the increased nuclear factor activity with the THC-induced increase in IL-2R alpha message, antisense oligodeoxynucleotides were used to inhibit expression of the RelA component of NF-kappaB. These results showed anti-RelA antisense eliminated the cannabinoid-induced upregulation of both alpha mRNA and RelA protein. Furthermore, inhibition of the cannabinoid receptor type 1 with antisense oligomers also eliminated the drug effect on the alpha message. These results suggest that THC treatment of NKB61A2 cells increases IL-2R alpha gene transcription by increasing the nuclear level of NF-kappaB through a mechanism involving cannabinoid receptor type 1 expression.

Animals↗
PubMed1997

A wavelet-based multiresolution regularized least squares reconstruction approach for optical tomography.

In this paper, we present a wavelet-based multigrid approach to solve the perturbation equation encountered in optical tomography. With this scheme, the unknown image, the data, as well as the weight matrix are all represented by wavelet expansions, thus yielding a multiresolution representation of the original perturbation equation in the wavelet domain. This transformed equation is then solved using a multigrid scheme, by which an increasing portion of wavelet coefficients of the unknown image are solved in successive approximations. One can also quickly identify regions of interest (ROI's) from a coarse level reconstruction and restrict the reconstruction in the following fine resolutions to those regions. At each resolution level a regularized least squares solution is obtained using the conjugate gradient descent method. This approach has been applied to continuous wave data calculated based on the diffusion approximation of several two-dimensional (2-D) test media. Compared to a previously reported one grid algorithm, the multigrid method requires substantially shorter computation time under the same reconstruction quality criterion.

Algorithms↗
PubMed1997

Regularized progressive expansion algorithm for recovery of scattering media from time-resolved data.

Reconstructions of the absorption cross sections of dense scattering media from time-resolved data are presented. A progressive expansion (PE) algorithm, similar to a layer-stripping, is developed to circumvent the underdeterminedness of the inverse problem. An overlapping scheme, which used detector readings from several consecutive time intervals, is introduced to reduce the propagation of reconstruction errors that occur at shallower depths. To reduce the sensitivity of the PE algorithm to noise a regularized progressive expansion (RPE) algorithm is proposed, which incorporates regularization techniques into the PE algorithm. The PE and the RPE algorithms are applied to the problem of image reconstruction from time-resolved data. The test media were isotropically scattering slabs containing one or two compact absorbers at different depths below the surface. The data were corrupted by additive white Gaussian noise with various strengths. The reconstruction results show that the PE and the RPE algorithms, when they are combined by proper overlapping, can effectively overcome the underdeterminedness of the inverse problem. The RPE algorithm yields reconstructions that are more accurate and more stable under the same noise level.

Algorithms↗
PubMed1997

Frequency-domain optical imaging of absorption and scattering distributions by a Born iterative method.

We presents a Born; iterative method, for reconstructing optical properties of turbid media by means of frequency-domain data. The approach is based on iterative solution of a linear perturbation equation, which is derived from the integral from of the Helmholtz wave equation for photon-density waves in each iteration the total field and the associated weight matrix are recalculated based on the previous reconstructed image. We then obtain a new estimate by solving the updated perturbation equation. The forward solution, also based on a Helmholtz equation, is obtained by a multigrid finite difference method. The inversion is carried out through a Tikhonov regularized optimization process by the conjugate gradient descent method. Using this method, we first reconstruct the distribution of the complex wave numbers in a test medium, from which the absorption and the scattering distributions are then derived. Simulation results with two-dimensional test media have shown that this method can yield quantitatively (in terms of coefficient valued) as well as qualitatively (in terms of object location and shape) accurate reconstructions of absorption and scattering distributions in cases in which the first-order Born approximation cannot work well. Both full-angle and limited-angle measurement schemes have been simulated to examine the effect of the location of detectors and sources. The robustness of the algorithm to noise has also been evaluated.

Absorption↗
PubMed1997

Iterative total least-squares image reconstruction algorithm for optical tomography by the conjugate gradient method.

We present an iterative total least-squares algorithm for computing images of the interior structure of highly scattering media by using the conjugate gradient method. For imaging the dense scattering media in optical tomography, a perturbation approach has been described previously [Y. Wang et al., Proc. SPIE 1641, 58 (1992); R. L. Barbour et al., in Medical Optical Tomography: Functional Imaging and Monitoring (Society of Photo-Optical Instrumentation Engineers, Bellingham, Wash., 1993), pp. 87-120], which solves a perturbation equation of the form W delta x = delta I. In order to solve this equation, least-squares or regularized least-squares solvers have been used in the past to determine best fits to the measurement data delta I while assuming that the operator matrix W is accurate. In practice, errors also occur in the operator matrix. Here we propose an iterative total least-squares (ITLS) method that minimizes the errors in both weights and detector readings. Theoretically, the total least-squares (TLS) solution is given by the singular vector of the matrix [W/ delta I] associated with the smallest singular value. The proposed ITLS method obtains this solution by using a conjugate gradient method that is particularly suitable for very large matrices. Simulation results have shown that the TLS method can yield a significantly more accurate result than the least-squares method.

Algorithms↗
PubMed1997

Epidemiology of adult poisoning at China Medical University.

OBJECTIVE: The objective of this study was to evaluate characteristics of the adult poisoned patient population at a university hospital in the People's Republic of China. METHODS: A prospective observational study was conducted at the Department of Emergency Medicine, China Medical University and included all poisoning cases presenting to the Emergency Department during a one year period. Data collection forms were designed and placed in the Emergency Department. Data were recorded by Emergency Department staff for all poisoned patients presenting during the study period (March 1, 1994 to February 28, 1995). RESULTS: Six hundred ninety-eight poisoned patients were collected in this study. Sedative/hypnotic agents (27.9%) were involved most commonly. The second most frequent toxicologic emergency was carbon monoxide (19%). Food poisoning was the third most common cause of poisoning (5.5%) and was equal to pesticide poisoning. The most common route of exposure was ingestion (71%). Twelve percent of the patients were admitted and 2.4% died. CONCLUSION: This first epidemiological report of adult poisoning from the People's Republic of China offers emergency physicians and toxicologists a preliminary understanding of the most common toxicologic problems seen in adults in a university hospital in China, and will aid in improving the delivery of emergency care to poisoned patients in the People's Republic of China.

Adolescent↗
PubMed1997

[Changes in external secretion of the pancreas in morphine-dependent rat].

The present study was done both in vivo by cannulating pancreatic duct of morphine-dependent rats and in vitro using perfused pancreatic slices from morphine-dependent rats. The results were as follows: (1) In morphine-dependent rat the pancreatic amylase secretion induced by CCK-8 was significantly declined; (2) Amylase content of pancreatic tissue in morphine-dependent rats was lower than that of normal rats. It is suggested that the synthesis of amylase in morphine-dependent rat pancreas may be inhibited.

Amylases↗
PubMed1997

[Epidemiological study on human prostate cancer in Wuhan City].

In America, Canada and many European countries, prostate cancer is the most common cancer and the second leading cause of cancer death in men. In China, the morbidity rate and mortality rate of prostate cancer are unknown. Based on the reports of Wuhan cancer surveillance in 1990-1992, this study researched the epidemiological characterics of prostate cancer. The results showed that morbidity rate and mortality rate in Wuhan city are 1.37 and 0.75 per 100,000 respectively, and the standardized morbidity rate and standardized mortality rate are 1.10 and 0.66 per 100,000 respectively. They also showed that history of urinary diseases (OR = 5.42, 95% confidence interval (CI): 1.56-18.83), children number with more than 3 (OR = 2.43, 95% CI: 1.17-5.02), coitus with more than 3 times per week in youth (OR = 3.38, 95% CI: 1.51-7.58), frequent use of sexual drugs (OR = 4.12, 95% CI: 1.65-10.25) and high body mass index (OR = 2.58; 95% CI: 1.30-5.11) are identified as risk factors of prostate cancer statistically, but physical labor (OR = 0.35, 95% CI: 0.17-0.71) and age of first nocturnal emission after 18 years old (OR = 0.20, 95% CI: 0.08-0.52) are protective factors.

Adult↗
PubMed1997

[Pharmacological study on magnetite].

Magnetite can markedly inhibit the rodent turn-around reaction induced by acetic acid, reduce the threshold dose of pentobarbital sodium and shorten rodent's incubation period of falling asleep. It has also the following effects; antagonizing metrazol which causes rodent convulsions, postponing the incubation period of being startled by Huisuling, cutting down the extent of rodent's foot swells caused by JCCJ, and diminishing bleeding time and congulating time.

Analgesics↗
PubMed1997

[Partial nucleotide sequencing of hepatitis E virus isolated from sera of patients with acute sporadic hepatitis E in China].

28 hepatitis E virus (HEV) cDNA isolates were obtained from 41 sera of patients with acute sporadic hepatitis E (HE) in Shenzhen, Changchun and Hangzhou by a reverse transcription nested polymerase chain reaction (RT-nPCR) and 3 of the 28 RT-nPCR products of HEV cDNA ORF2 region were sequenced. The nucleotide homology of these three HEV isolates was 80.2%, 79.9% and 79.4%, respectively, as compared with the Maxico strain of HEV (M); 93.4%, 92.3% and 93.8% with the Burma epidemic strain of HEV(B) (Ep); 95.5%, 93.9% and 95.1% with the Burma sporadic strain of HEV(B) (Sp); 97.0%, 96.5% and 95.9% with the Xinjiang epidemic strain of HEV CH 1.1. It is demonstrated that these three isolates of HEV obtained from sera of acute sporadiic hepatitis E cases have a higher degree of homology with the Xinjiang strain of HEV CH 1.1 and the Burma strain of HEV(B). The data indicate that these three HEV isolates may belong to HEV(B) subtype, as the HEV CH 1.1 does.

Amino Acid Sequence↗