Biomedical subjects

Y Hu

Publications and source records attributed to Y Hu.

At least 109 records · Page 6Linked to original sources

PubMed2001

An algorithm for stereotactic localization by computed tomography or magnetic resonance imaging.

Stereotactic localization of an intracranial lesion by computed tomography or magnetic resonance imaging requires the use of a head frame that is fixed to the skull of the patient. To such head frames are attached either N-shaped or V-shaped localization rods. Because of patient positioning, the transverse imaging slices may not be parallel to the frame base; a coordinate transformation algorithm that takes this possibility into consideration is crucial. Here we propose such an algorithm for a head frame with V-shaped localization rods. Our algorithm determines the transformation matrix between the image coordinate system of a transverse image and the frame coordinate system. The determining procedure has three steps: (a) calculation of the oblique angles of a transverse image relative to the head frame and calculation of the image magnification factor; (b) determination of the coordinates of four central markers in both coordinate systems; and (c) determination of the 3 x 3 transformation matrix by using the coordinates of the four markers. This algorithm is robust in principle and is useful for improving the accuracy of localization.

Algorithms↗

PubMed2001

Effects of low O2 and ageing on spindles and chromosomes in mouse oocytes from pre-antral follicle culture.

To assess their quality, spindles were analysed in mouse oocytes from pre-antral follicle culture. High or low oxygen tension was present during the last 16 or 20 h post human chorionic gonadotrophin (HCG)/epidermal growth factor (EGF) addition. Most oocytes from pre-antral follicle culture possessed typical anastral spindles with flat poles resembling those of ovulated, in-vivo-matured oocytes of sexually mature mice, while denuded oocytes in-vitro matured to metaphase II (MII) formed significantly longer, slender spindles with pointed, narrow poles. Spindles in oocytes from follicle culture were only slightly shorter and less compact at the equator as compared with those of oocytes matured in vivo. Chromosomes were well aligned at the equator in MII oocytes obtained from follicle culture with high oxygen. Maturation rate was significantly reduced by lowering oxygen tension to 5% O2. Prolonged culture and the presence of only 5% O2 dramatically increased the percentage of MII oocytes with unaligned chromosomes. These observations indicate that sufficient oxygen supply and time of retrieval after initiation of resumption of maturation by HCG as well as the microenvironment and cell-cell interactions between oocytes and their somatic compartment are critical in affecting the oocyte's capacity to mature to MII, to form a functional spindle, and to align chromosomes correctly.

Animals↗

PubMed2001

Effect of stimulus pulse duration on intraoperative somatosensory evoked potential (SEP) monitoring.

The effect of the stimulus duration on the amplitude and latency of intraoperative somatosensory evoked potential (SEP) was studied in 30 patients with idiopathic scoliosis undergoing surgery. Constant current square-wave electrical stimulation was applied to the posterior tibial nerve at a rate of 5.1 Hz. The effects of both the pulse duration and the stimulus current density on the intraoperative SEP were evaluated. Amplitudes and latencies of SEP were analyzed by one-way parametric analysis of variance. SEP signal recording was found to be difficult if the stimulus duration was less than 0.05 ms. The stimulus duration had no significant effect on the latencies of the SEP, but the amplitude of the SEP showed significant changes with differing stimulus durations. The SEP amplitudes were found with significant increases in pulse durations less than 0.3 ms. Stimulus pulse duration has a significant effect on SEP amplitude, and this should be taken into consideration during intraoperative SEP monitoring. A pulse duration of 0.3 ms is recommended for SEP using posterior tibial nerve stimulation.

Adolescent↗

PubMed2001

Effect of stimulation parameters on intraoperative spinal cord evoked potential monitoring.

The purpose of this study was to investigate the effects of the stimulus parameters on spinal cord evoked potential (SCEP) and to recommend a practical epidural stimulation protocol for intraoperative spinal cord monitoring. This prospective study compared the latencies and amplitudes of SCEP obtained on epidural stimulation of 30 patients with scoliosis under anesthesia using different stimulus pulse duration and stimulation rates. SCEP was found to be undetectable with shorter stimulus duration (<0.05 ms). The SCEP latencies did not show any significant difference among different stimulation parameters. However, the SCEP amplitude showed significant changes with differing stimulus durations. The SCEP amplitudes were found to significantly decrease when the pulse durations become shorter than 0.2 ms. Stimulus parameters showed significant effects on SCEP amplitude but not latency. Stimulus rates in the range of 21 to 61 Hz are equivalent for quick and reliable detection of SCEP. Considering the short latency of SCEP, a pulse duration of 0.2 ms is recommended for SCEP using epidural stimulation.

Adolescent↗

PubMed2001

Isolation and characterization of kinase interacting protein 1, a pollen protein that interacts with the kinase domain of PRK1, a receptor-like kinase of petunia.

Many receptor-like kinases have been identified in plants and have been shown by genetic or transgenic knockouts to play diverse physiological roles; however, to date, the cytosolic interacting proteins of relatively few of these kinases have been identified. We have previously identified a predominantly pollen-expressed receptor-like kinase of petunia (Petunia inflata), named PRK1, and we have shown by the antisense RNA approach that it is required for microspores to progress from the unicellular to bicellular stage. To investigate the PRK1-mediated signal transduction pathway, PRK1-K cDNA, encoding most of the cytoplasmic domain of PRK1, was used as bait in yeast (Saccharomyces cerevisiae) two-hybrid screens of pollen/pollen tube cDNA libraries of petunia. A protein named kinase interacting protein 1 (KIP1) was found to interact very strongly with PRK1-K. This interaction was greatly reduced when lysine-462 of PRK1-K, believed to be essential for kinase activity, was replaced with arginine (the resulting protein is named PRK1-K462R). The amino acid sequence of KIP1 deduced from full-length cDNA contains an EF-hand Ca(2+)-binding motif and nine predicted coiled-coil regions. The yeast two-hybrid assay and affinity chromatography showed that KIP1 interacts with itself to form a dimer or higher multimer. KIP1 is present in a single copy in the genome, and is expressed predominantly in pollen with a similar temporal pattern to PRK1. In situ hybridization showed that PRK1 and KIP1 transcripts were localized in the cytoplasm of pollen. PRK1-K phosphorylated KIP1-NT (amino acids 1--716), whereas PRK1-K462R only weakly phosphorylated KIP1-NT in vitro.

Amino Acid Sequence↗

PubMed2001

Yaba-like disease virus: an alternative replicating poxvirus vector for cancer gene therapy.

Vaccinia virus is being investigated as a replicating vector for tumor-directed gene therapy. However, the majority of cancer patients have preformed immunologic reactivity against vaccinia virus, as a result of smallpox vaccination, which may limit its use as a vector. The Yaba-like disease (YLD) virus was investigated here as an alternative, replicating poxvirus for cancer gene therapy. We have demonstrated that the YLD virus does not cross-react with vaccinia virus antibodies, and it replicates efficiently in human tumor cells. YLD virus can be expanded and purified to high titer in CV-1 cells under conditions utilized for vaccinia virus. The YLD virus RNA polymerase was able to express genes regulated by a synthetic promoter designed for use in orthopoxviruses. We sequenced the YLD virus TK gene and created a shuttle plasmid, which allowed the recombination of the green fluorescent protein (GFP) gene into the YLD virus. In a murine model of ovarian cancer, up to 38% of cells in the tumor expressed the GFP transgene 12 days after intraperitoneal virus delivery. YLD virus has favorable characteristics as a vector for cancer gene therapy, and this potential should be explored further.

Animals↗

PubMed2001

Prevention of spinal cord injury with time-frequency analysis of evoked potentials: an experimental study.

OBJECTIVES: To verify the applicability and validity of time-frequency analysis (TFA) of evoked potential (EP) signals in detecting the integrity of spinal cord function and preventing spinal cord injury. METHODS: The spinal cord was simulated during surgery in 20 mature rats by mechanically damaging the spinal cord. Cortical somatosensory evoked potential (CSEP), spinal somatosensory evoked potential (SSEP), cortical motor evoked potential (CMEP), and spinal cord evoked potential (SCEP) were used to monitor spinal cord function. Short time Fourier transform (STFT) was applied to the CSEP signal, and cone shaped distribution (CSD) was used as the TFA algorithm for SSEP, CMEP, and SCEP signals. The changes in the latency and amplitude of EP signals were measured in the time domain, and peak time, peak frequency, and peak power were measured in the time-frequency distribution (TFD). RESULTS: The TFDs of EPs were found to concentrate in a certain location under normal conditions. When injury occurred, the energy decreased in peak power, and there was a greater dispersion of energy across the time-frequency range. Strong relations were found between latency and peak time, and amplitude and peak power. However, the change in peak power after injury was significantly larger than the corresponding change in amplitude (p<0.001 by ANOVA). CONCLUSIONS: It was found that TFA of EPs provided an earlier and more sensitive indication of injury than time domain monitoring alone. It is suggested that TFA of EP signals should therefore be useful in preventing spinal cord injury during surgery.

Algorithms↗

PubMed2001

Local gene transfer of tissue inhibitor of metalloproteinase-2 influences vein graft remodeling in a mouse model.

Recently, we established a new mouse model of vein graft arteriosclerosis by grafting vena cava to carotid arteries. In many respects, the morphological features of this murine vascular graft model resemble those of human venous bypass graft disease. Using this model, we studied the effects of local gene transfer of tissue inhibitor of metalloproteinase-2 (TIMP-2) on vein graft remodeling. Mouse isogeneic vessels of the vena caval veins were grafted end to end into carotid arteries, then enveloped with the replication-defective recombinant adenoviruses overexpressing human TIMP-2 (RAdTIMP-2) or beta-galactosidase (RAdLacZ) at 1x10(10) plaque-forming units/mL in a total volume of 50 microL, and incubated at room temperature for 20 minutes. In the untreated group, vessel wall thickening was observed as early as 1 week after surgery and progressed to 4- to 10-fold the original thickness in grafted veins at 4 and 8 weeks, respectively. RAdLacZ vector treatment significantly enhanced neointimal lesions at 8 weeks, which was completely blocked by RAdTIMP-2 gene overexpression. Interestingly, RAdTIMP-2 gene transfer resulted in a reduction in vessel diameter of grafted veins compared with ungrafted veins (819+/-96 versus 624+/-67 microm, respectively; P<0.05). Maximal beta-galactosidase activity was found at 2 weeks and was detectable until 4 weeks after gene transfer. Double immunofluorescence studies demonstrated that cells overexpressing TIMP-2 were mostly localized in the adventitia and were MAC-1-positive monocytes/macrophages but not smooth muscle cells. Furthermore, the activity of matrix metalloproteinases was markedly decreased in the vessel walls treated with RAdTIMP-2 compared with that in the untreated control group and the RAdLacZ-treated group. Thus, this mouse model has been proven to be useful in gene transfer studies. Our findings demonstrate that local TIMP-2 gene transfer significantly reduces vein graft diameter, ie, remodeling to an artery-like vessel via inhibition of matrix metalloproteinase activity.

Adenoviridae↗

PubMed2001

Exacerbated vein graft arteriosclerosis in protein kinase Cdelta-null mice.

Smooth muscle cell (SMC) accumulation is a key event in the development of atherosclerosis, including vein bypass graft arteriosclerosis. Because members of the protein kinase C (PKC) family signal cells to undergo proliferation, differentiation, or apoptosis, we generated PKCdelta knockout mice and performed vein bypass grafts on these animals. PKCdelta(-/-) mice developed normally and were fertile. Vein segments from PKCdelta(-/-) mice isografted to carotid arteries of recipient mice of either genotype led to a more severe arteriosclerosis than was seen with PKCdelta(+/+) vein grafts. Arteriosclerotic lesions in PKCdelta(-/-) mice showed a significantly higher number of SMCs than were found in wild-type animals; this was correlated with decreased SMC death in lesions of PKCdelta(-/-) mice. SMCs derived from PKCdelta(-/-) aortae were resistant to cell death induced by any of several stimuli, but they were similar to wild-type SMCs with respect to mitogen-stimulated cell proliferation in vitro. Furthermore, pro-apoptotic treatments led to diminished caspase-3 activation, poly(ADP-ribose) polymerase cleavage, and cytochrome c release in PKCdelta(-/-) relative to wild-type SMCs, suggesting that their apoptotic resistance involves the loss of free radical generation and mitochondrial dysfunction in response to stress stimuli. Our data indicate that PKCdelta maintains SMC homeostasis and that its function in the vessel wall per se is crucial in the development of vein graft arteriosclerosis.

Animals↗

PubMed2001

Epidemiological studies on hearing impairment with reference to genetic factors in Sichuan, China.

Hearing impairment is the most common disorder of sensorineural function and is an economically and socially important cause of human morbidity. A large-scale epidemiological survey of hearing loss was conducted with 126,876 unselected subjects (63,741 male and 63,135 female) from Sichuan, China. The overall prevalence of hearing loss was 3.28% (4,164 of 126,876), and the prevalence increased with age, reaching 12.8% (1,465 of 11,421) at 60 years of age. In 73.03% of all cases (3,041 of 4,164), the hearing loss was sensorineural, and in 20.39% (849 of 4,164), it was conductive; the remaining cases (6%) were mixed hearing loss. Bilateral loss was found in 74.5% of cases (3,103 of 4,164). In 63.79% of cases (2,656 of 4,164), the degree of hearing loss was less than 55 dB hearing level (HL), and in 5.67% of cases (236 of 4,164), it was greater than 90 dB HL. The prevalence of hearing loss in childhood (<15 years of age) was 0.67% (227 of 34,157), of which 57.7% of cases were conductive and 38.8% were sensorineural. The prevalence of genetic hearing loss was 0.28% (349 of 126,876). Persons who lived in the flatlands appeared to have a higher prevalence than those who lived in the hills. Several ethnic groups, including Tibetans, the Yi, and the Lisu, had a higher prevalence of hearing loss. Presbycusis, otitis media, and genetic factors were the most commonly recognized causes of hearing impairment overall, but otitis media and genetic factors were the main causes of hearing loss in children. Causes for the observed differences in prevalence and etiologic factors between China and industrialized countries will be discussed. In China, infections and genetic factors appear to be of major importance as causes of hearing loss.

Adolescent↗

PubMed2001

Biological effects of long-term caloric restriction: adaptation with simultaneous administration of caloric stress plus repeated immobilization stress in rats.

In the present study, we have established the biological effects during 8 weeks of (i) caloric restriction (Cal) and (ii) simultaneous administration of Cal plus 2 hr daily immobilization stress using male Sprague-Dawley rats. Animals were divided into three equal groups: (i) ad libitum fed, (ii) 30% restriction of food intake of the ad libitum diet, and (iii) 30% restriction of food intake plus 2 hr daily immobilization stress. Caloric-restricted animals gained only 30% of the total body weight of the unrestricted animals but received 70% of the food of those rats. Cal animals showed a significant loss in their relative liver and-thymus weight and a significant gain in their relative adrenal and testis weight as compared to the control animals. Cal animals had almost 2-fold higher levels of plasma corticosterone levels with a dramatic decrease in the total glucocorticoid receptor (GR) levels in the liver, thymus, heart, and testis as compared to ad libitum fed control animals. Interestingly, Cal animals showed higher levels of lipid peroxidation in both the liver and heart, indicating increased oxidative activities in these tissues when compared with the control animals. In addition, Cal animals had increased heat shock protein 70 (HSP 70) content in the testis. Surprisingly, hardly any significant differences were observed in either total body weight gain, organ weights, plasma corticosterone levels, or lipid peroxidation between Cal animals and Cal plus immobilization-stressed animals. The results obtained suggest that (i) several stress-related responses such as inhibition of total body weight gain, increased adrenal weight, decreased thymus weight, increased plasma corticosterone, and lipid peroxidation levels in the liver and heart are associated with Cal, but (ii) no additional effects were observed on the parameters that were measured when two stress regimens were given simultaneously, suggesting that animals subjected to two stress regimens can protect themselves by controlling their stress-related thresholds of response through adaptation.

Adaptation, Biological↗

PubMed2001

A non-potentiometric sensing method for the determination of pentoxyverine with PQC sensors based on ion-pair complexes.

The construction and general performance characteristics of three piezoelectric quartz crystal sensors responsive to the pentoxyverine are described here. This kind of non-potentiometric sensing method is based on use of ion-pair complexes of the pentoxyverine cation with three counter anions, namely, tungstophosphate, tetraphenylborate and picrolonate. The complexes were embedded in a PVC matrix. Adsorption of the pentoxyverine ion on the complex caused a frequency decrease of the crystal. The frequency decrease was proportional to the amount of adsorbed analyte. The influencing factors were investigated in detail, and then optimized. The proposed sensors exhibit reasonable selectivity and a higher sensitivity than the potentiometric sensors. For a sensor modified with pentoxyverine-phosphotungstate, the calibration graph was linear over concentration of 1.0 x 10(-7) - 5.0 x 10(-5) M with a detection limit of 6 x 10(-8) M at pH 5.4.

Antitussive Agents↗

PubMed2001

Controlled release from coated polymer microparticles embedded in tissue-engineered scaffolds.

The controlled release of proteins in tissue-engineered implants is being examined with the potential application to improve vascularization and hasten tissue growth. Bovine serum albumin (BSA), was encapsulated within poly(D,L-lactic-co-glycolic acid) [PLGA] microparticles. The microparticles were coated with poly(vinyl alcohol) and incorporated into PLGA tissue-engineered scaffolds during fabrication. The release of BSA from PLGA microparticles, coated PLGA microparticles, and microparticles embedded in a porous PLGA scaffold was measured. We have developed a novel approach that will permit incorporation of coated polymeric microparticles during PLGA scaffold fabrication. Growth factors or drugs could be incorporated into the microparticles resulting in a long-term, controlled release.

Animals↗

PubMed2001

New type II manumycins produced by Streptomyces nodosus ssp. asukaensis and their biosynthesis.

Five new type II manumycins, containing the hydroxyquinol mC7N unit, asukamycins A-II, B-II, C-II, D-II, E-II, were discovered in cultures of Streptomyces nodosus ssp. asukaensis. The biosynthetic origin of the type II manumycins from the type I compounds, containing an epoxyquinol mC7N unit, was deduced from the time course of production and proven by preparing [7'-13C]asukamycin A and demonstrating its incorporation into asukamycin A-II.

Anti-Bacterial Agents↗

PubMed2001

[An ECG waves separation technique based on mathematical morphology].

An ECG waves separation technique based on mathematical morphology is suggested and discussed in this paper. Without detection of QRS complexes, the QRS complexes can be eliminated by series morphological operations. Then the start points and end points of P-wave and T-wave can be decided and the waves of ECG are separated qualitatively and quantitatively. The results of qualitative separations are rather satisfied and the SDs of quantitative separation results are not very large. Also, ECG signals are filtered and baseline is normalized by morphological method.

Algorithms↗

PubMed2001

[Fast SEP measurement applied to intraoperative spinal cord monitoring].

Spinal cord monitoring techniques based on measuring somatosensory evoked potential (SEP) are presented. The principles and the experimental system for spinal cord monitoring are described in detail in the paper. The fast SEP measurement algorithm using pseudo-random sequence technique is also given. Experimental results show that our techniques can greatly improve the monitoring as compared to the traditional method, and further research in this connection is worth doing.

Algorithms↗

PubMed2001

[Changes of lipid peroxidation in liver fibrogenesis induced by dimethylnitrosamine and drugs' intervention].

OBJECTIVE: To investigate the pathological actions of lipid peroxidation implicated in liver fibrogenesis induced by dimethylnitrosamine (DMN), and the mechanism of Fuzheng Huayu 319 decoction (319 decoction) and interferon-gamma (IFN-gamma) actions against liver fibrosis. METHODS: A liver fibrotic model was induced by intraperitoneal injection of DMN in rats, and treated with 319 decoction and IFN-gamma, respectively. The liver sections were stained with HE and ponceau for collagens, and the liver functions were assayed. The contents of hepatic hydroxyproline (Hyp) and malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) were measured. The correlation among SOD, MDA and Hyp was analyzed. RESULTS: In the models, hepatic collagens proliferated remarkably and fibrous septa were formed. Serum ALT activities increased. Both Hyp and MDA enhanced obviously, but SOD decreased markedly. SOD was significantly negatively correlated with MDA and Hyp, respectively (r=-0.70, -0.73, P<0.01), and MDA was significantly positively correlated with Hyp (r=0.88, P<0.01). While both 319 decoction and IFN-gamma attenuated collagen proliferation and deposition, decreased ALT level, increased SOD activity, but decreased MDA and Hyp contents. CONCLUSIONS: DMN can cause hepatic lipid peroxidation, which is closely involved in liver fibrogenesis induced by DMN. The effect against hepatic lipid peroxidation is one of the important mechanisms of 319 decoction and IFN-gamma actions against liver fibrosis.

Animals↗

PubMed2001

Automatic analysis of image of surface structure of cell wall-deficient EVC.

Some computer applications for cell characterization in medicine and biology, such as analysis of surface structure of cell wall-deficient EVC (El Tor Vibrio of Cholera), operate with cell samples taken from very small areas of interest. In order to perform texture characterization in such an application, only a few texture operators can be employed: the operators should be insensitive to noise and image distortion and be reliable in order to estimate texture quality from images. Therefore, we introduce wavelet theory and mathematical morphology to analyse the cellular surface micro-area image obtained by SEM (Scanning Electron Microscope). In order to describe the quality of surface structure of cell wall-deficient EVC, we propose a fully automatic computerized method. The image analysis process is carried out in two steps. In the first, we decompose the given image by dyadic wavelet transform and form an image approximation with higher resolution, by doing so, we perform edge detection of given images efficiently. In the second, we introduce many operations of mathematical morphology to obtain morphological quantitative parameters of surface structure of cell wall-deficient EVC. The obtained results prove that the method can eliminate noise, detect the edge and extract the feature parameters validly. In this work, we have built automatic analytic software named "EVC.CELL".

Cell Membrane↗