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Biomedical subjects

H Wu

Publications and source records attributed to H Wu.

At least 181 records · Page 10Linked to original sources
PubMed2001

Probabilities of radiation-induced inter- and intrachromosomal exchanges and their dependence on the DNA content of the chromosome.

A biophysical model has been developed that is based on the assumptions that an interphase chromosome occupies a spherical territory and that chromosome exchanges are formed by the misrejoining of two DNA double-strand breaks induced within a defined interaction distance. The model is used to explain the relative frequencies of inter- and intrachromosomal exchanges and the relationship between radiation-induced aberrations in individual chromosomes and the DNA content of the chromosome. Although this simple model predicts a higher ratio of inter- to intrachromosomal exchanges for low-LET radiation than for high-LET radiation, as has been suggested by others, we argue that the comparison of the prediction of the model with experimental results is not straightforward. With the model, we also show that the probability of the formation of interchromosomal exchanges is proportional to the "surface area" of the chromosome domain plus a correction term. The correction term is small if the interaction distance is less than 1 microm for both low- and high-LET radiations.

Chromosome Aberrations↗
PubMed2001

Chromosome aberrations in the blood lymphocytes of astronauts after space flight.

Cytogenetic analysis of the lymphocytes of astronauts provides a direct measurement of space radiation damage in vivo, which takes into account individual radiosensitivity and considers the influence of microgravity and other stress conditions. Chromosome exchanges were measured in the blood lymphocytes of eight crew members after their respective space missions, using fluorescence in situ hybridization (FISH) with chromosome painting probes. Significant increases in aberrations were observed after the long-duration missions. The in vivo dose was derived from the frequencies of translocations and total exchanges using calibration curves determined before flight, and the RBE was estimated by comparison with individually measured physical absorbed doses. The values for average RBE were compared to the average quality factor (Q) from direct measurements of the lineal energy spectra using a tissue-equivalent proportional counter (TEPC) and radiation transport codes. The ratio of aberrations identified as complex was slightly higher after flight, which is thought to be an indication of exposure to high-LET radiation. To determine whether the frequency of complex aberrations measured in metaphase spreads after exposure to high-LET radiation was influenced by a cell cycle delay, chromosome damage was analyzed in prematurely condensed chromosome samples collected from two crew members before and after a short-duration mission. The frequency of complex exchanges after flight was higher in prematurely condensed chromosomes than in metaphase cells for one crew member.

Chromosome Aberrations↗
PubMed2001

Identification of the human homologue of the early-growth response gene Snk, encoding a serum-inducible kinase.

Murine serum inducible kinase (mSnk) was recently cloned and characterized as an early-growth response gene involved in cell proliferation. Here we report the isolation and characterization of its human homologue, named hSnk. Sequence comparison shows that hSnk is highly conserved and its deduced protein sequence shares a significant amino acid identity with mSnk and rSnk proteins, as well as with other polo family kinase gene products. A survey of hSnk expression reveals that while a wide variety of human tissues express a low to moderate level of hSnk transcripts, fetal tissues, testis, and spleen express the most abundant hSnk transcripts. In addition, serum stimulation rapidly induces hSnk expression in fibroblast cells, reaching the peak level of induction within one hour post treatment. Considering that Plk and Prk, two other known human polo-family kinases, control cell cycle checkpoint and cell cycle progression, our current observations suggest that hSnk may also play an important role in cells undergoing rapid cell division or having a high mitotic index.

Adenosine Triphosphate↗
PubMed2001

Mechanism of the immune response to human factor VIII in murine hemophilia A.

Mice genetically deficient in factor VII (fVIII) are a model of hemophilia A. As a first step to reproduce in this mouse model what occurs over time in hemophilia A patients treated with human fVIII (hfVIII), we have investigated the time course and the characteristics of their immune response to hfVIII, after multiple intravenous injections. Anti-hfVIII antibodies appeared after four to five injections. They were IgG1 and to a lesser extent IgG2, indicating that they were induced by both Th2 and Th1 cells. Inhibitors appeared after six injections. CD4+ enriched splenocytes from hfVIII-treated mice proliferated in response to fVIII and secreted IL-10: in a few mice they secreted also IFN-gamma and in one mouse IL-4, but never IL-2. A hfVIII-specific T cell line derived from hfVIII-treated mice secreted both IL-4 and IFN-gamma, suggesting that it included both Th1 and Th2 cells. CD4+ enriched splenocytes of hfIII-treated mice recognized all hfVIII domains. Thus, hemophilic mice develop an immune response to hfVIII administered intravenously similar to that of hemophilia A patients. Their anti-hfVIII antibodies can be inhibitors and belong to IgG subclasses homologous to those of inhibitors in hemophilic patients; their anti-hfVIII CD4+ cells recognize a complex repertoire and both Th1 and Th2 cytokines, and especially IL-10, may drive the antibody synthesis.

Animals↗
PubMed2001

Cyclooxygenase-2 overexpression is a marker of poor prognosis in stage I non-small cell lung cancer.

Cyclooxygenase-2 (COX-2), the enzyme that converts arachidonic acid to prostaglandins, is overexpressed in a variety of different tumors, including those of the colon, pancreas, lung, and head and neck. We used in situ hybridization with a digoxgenin-labeled COX-2 antisense riboprobe to assess the presence of strong or intermediate versus weak or absent COX-2 expression in specimens from 160 patients with stage I non-small cell lung cancer (NSCLC). Of these, 3 specimens had strong expression, 69 had intermediate expression of COX-2, 24 had weak expression, and 64 had no detectable COX-2. The strength of COX-2 expression was associated with a worse overall survival rate (P = 0.001) and a worse disease-free survival rate (P = 0.022). The median survival times for the strong, intermediate or weak, and null COX-2 expressors were 1.04, 5.50, and 8.54 years, respectively. Interestingly, all three specimens with strong COX-2 expression came from patients who died within 18 months. Retinoic acid receptor beta (RAR-beta) is a nuclear retinoid receptor whose expression is frequently lost in aerodigestive tract carcinogenesis. We previously demonstrated that expression of RAR-beta in stage I NSCLC indicates a poor prognosis. Retinoids have been shown to prevent induction of COX-2 by mitogens and tumor promoters. Expression of COX-2 correlated with RAR-beta expression (P = 0.053), but not with k-ras mutational status, vascular endothelial growth factor, basic fibroblast growth factor, interleukin 8 levels, or other markers of angiogenesis, invasion, and metastases. Thus, like RAR-beta positivity, COX-2 overexpression appears to portend a shorter survival among patients with early stage non-small cell lung cancer. Future studies of RAR-beta and COX-2 regulation in NSCLC should further the development of prevention and therapy interventions with retinoids and/or COX-2 antagonists in this patient population.

Biomarkers, Tumor↗
PubMed2001

[Telomere length and DCC gene mRNA expression of human large intestine cancers].

OBJECTIVE: To evaluate the role of telomere and DCC in tumor transformation and progression. METHODS: Telomere length and DCC gene mRNA expression were examined by southern blot hybridization and RT-PCR analysis in 46 adenomas of large intestine, 62 cancers of large intestine and corresponding normal mucosa. RESULTS: Shortening of the telomere was present in the tissues of 41.3% of the adenomas and 53.2% of the cancers, and their average TRF lengths were significantly shorter than those of corresponding normal mucosa(P<0.05, P<0.01), whereas the telomere elongation was only detected in 4.4% and 6.5% of the adenomas and cancers respectively. In addition, the average telomere length in colon carcinomas was also shorter than that in rectal carcinomas. Moreover, the average telomere lengths of the colorectal cancer mucosa became shorter with age. The rates of DCC mRNA expression deletion were 34.8% and 62.9% in the tissues of adenomas and cancers respectively. The DCC mRNA expression deletion occurred more frequently in poorly differentiated and Dukes C, D carcinomas than in well-differentiated and Dukes A, B carcinomas (P<0.05, P<0.01). However, no significant correlation was found between the length of telomere and the deletion of DCC mRNA expression in the cancers of large intestine. CONCLUSION: The telomere shortening and DCC mRNA deletion may represent the biologic behavior of transformation and development of the large intestine cancers.

Adult↗
PubMed2001

[Experimental studies on muscle fatigue of human limb motion with FNS].

The basic characteristic of the functional neuromuscular stimulation signals suitable to body is preliminarily determined after the fatigue performance of the biceps, and the physiological reaction to stimulation is investigated using many continuous stimulation signal patterns. The flexion motion of the elbow joint (right hand) of a healthy man was taken as our research objective. The surface electrodes were connected to the biceps and a micro angle sensor was mounted on the elbow joint (right hand). The curves of angular displacement for the elbow joint motion were obtained by using functional neuromuscular stimulation (FNS) limbs motion measurement instruments. The results demonstrate that the biceps are characterized by the non-linear and time-variant no matter what the stimulation patterns are, that continuous slow stimulation signals can reduce the muscle fatigue of the biceps, and that the stimulation frequencies ranging from 30 Hz to 50 Hz are applicable to the neuromuscular system.

Adult↗
PubMed2001

[High polymorphism at the human P gene locus in Chinese Han and Tibetan populations].

OBJECTIVE: The authors studied two synonymous sites polymorphism (A355A, G780G) and one intervening sequence polymorphism(IVS13-15) of human P gene in 181 and 171 individuals sampled from Chinese Han and Tibetan populations respectively. METHODS: Genomic DNA was extracted from the ACD-blood specimens collected from 352 healthy unrelated individuals by phenol-chloro methods. The amplification of three fragments was performed using PCR technique; the product was digested with restricted enzyme. Agarose electrophoresis was used for typing the PCR product. RESULTS: There were two alleles at each exon variety locus; the allele frequencies in both A355A and G780G were of significant differences between the two populations ( chi(2)=24.54,chi(2)=37.05,P>0.001). No significant difference was found in allele frequency in IVS13-15 locus between the two populations (chi(2)=2.06,P>0.05). And in each of the populations, no significant difference was noted in the genotype frequency between the male and the female. The test for Hardy-Weinberg equilibrium showed that the genotype distributions observed in the two populations were correspondent with the expected. CONCLUSION: There is a remarkable difference in the distribution of allele frequencies at P gene locus between Chinese Han and Tibetan populations, which is related to the variation in skin pigmentation of these two Chinese population.

Adolescent↗
PubMed2001

[Effects of tumor necrosis factor alpha on the expression of connective tissue growth factor in hepatic stellate cells].

OBJECTIVE: To investigate the effect of tumor necrosis factor alpha (TNF-alpha) on the expression of connective tissue growth factor (CTGF) in rat hepatic stellate cells (HSC) in vitro. METHODS: HSCs were prepared from SD rats by in situ perfusion and single-step Nycodenz gradient, and were treated with TNF-alpha and TGF-beta 1. The expression of CTGF in HSC was assessed using reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Both TNF-alpha and TGF-beta 1 could stimulate the expression of CTGF mRNA in HSC. The expression of CTGF was not found in HSC after treatment with TNF-alpha(10microgram/L) for 6 hours, but was observed after TNF-alpha treatment for 24 and 48 hours. TGF-beta1 could induce the mRNA expression for CTGF just after 6 hours of treatment at 1microgram/L concentration. CONCLUSIONS: TNF-alpha is able to induce the expression of CTGF in HSC, and this may be one of the mechanisms for TNF-alpha involving in the liver fibrosis.

Animals↗
PubMed2001

[The research of mathematical model for inositol-1,4,5-triphosphate-induced Ca2+ oscillations].

This article mainly illustrates the model for agonist-stimulated Ca2+ oscillations that involves two roles for cytosolic Ca2+: (a) inositol-1.4.5-triphosphate(IP3) inhibits Ca2+ release from the endoplasmic reticulum (ER); (b) IP3 acts on phosphate C, via a Gq protein related mechanism and hence stimulates Ca2+ release from ER. The model assumes that the ER IP3 receptor is a tetramer of independent subunit that can bind both Ca2+ and IP3. The reason for inhibition of Ca2+ oscillations is that IP3-receptor/Ca(2+)-channel slowly comes back to the beginning stable state. The key parameter for Ca2+ oscillations is the ratio of Maximum Ca2+ dependent IP3 input rate (v6) to IP3 decay rate constant (v7): I when v6/v7 < 0.28, no oscillation could be found; II when 0.28 < v6/v7 < 0.572, oscillation starts; III when v6/v7 > 0.572, Ca2+ ceases and arrives at a stable state quickly.

Calcium Channels↗
PubMed2001

[Numerical study of the effects (correction of efects) of size of inlets and outlets of ventilation system in experimental space station cabin].

OBJECTIVE: To make the status of flow and heat transfer fit the requirement of comfortable condition in the experimental cabin and ventilation and cooling in the apparatus cabin of the space station. METHOD: In present numerical simulation, a model approximate the practice at condition of the ventilation pipeline and influence of inlet and outlet was used, so that there is no need of supposing the distribution of outlets. In microgravity condition, the influence of the size of inlets and outlets on the flow field in the experimental space station cabin was studied. According to different function zones in the experimental space station cabin, the region at evenness parameter was put forward. RESULT: The taper inlet and crescent outlet had the best integrated performance. CONCLUSION: The use of variational section was recommended in designing and building of ventilation project in space station cabin.

Air Conditioning↗
PubMed2001

[A two-years clinical observation of all-ceramic restorations using Vita In-Ceram glass-infiltrated ceramic].

OBJECTIVE: This paper observed the clinical effect of Vita In-Ceram glass-infiltrated ceramic restorations. METHOD: A total of 194 restorations (124 maxillary and 70 mandibular prostheses) made with Vita In-Ceram glass-infiltrated ceramic were examined in 45 patients. There were 165 anterior tooth crowns, 21 posterior tooth crowns, and 8 FPDs. Surface, color, anatomic form, and marginal integrity of restorations were assessed at 3 months, 6 months, 1 year and 2 years after cementation with the California Dental Association (CDA) quality assessment evaluation system. RESULTS: It showed that the marginal fitness, color stability and strength of crowns were considered to be satisfactory. Only 0.01% (two crowns) were not acceptable. Two FPDs were not acceptable at 6-month visit, however, the anterior FPDs were considered to be satisfactory. CONCLUSION: It is possible to constructexcellent all-ceramic prostheses with the Vita In-Ceram glass-infiltrated ceramic system.

Ceramics↗
PubMed2001

[Characteristics and distribution pattern of farmland patch in river valley in middle and low Taihang mountain area--a case study in Yanzhi River in Fuping County, Hebei Province].

Based on the investigations in the main valley of Yanzhi river in Fuping county of Hebei Province, the characteristics and distribution patterns were analyzed. The results indicated that farmland patches were distributed in the whole valley, except the headstream reach. With the increase of human disturbances, the proportion of farmlands increased along the river from upstream to downstream, while in natural landscapes, the environmental heterogeneity and fragmentation of farmlands decreased. The area of Yanzhi river valley totaled 2297.09 hm2, mainly composed by farmland. There were 117 farmland patches mainly distributed along the riverbank in the valley, totalling 1027.78 hm2 and occupying 44.74% of the valley, which were very well irrigated, but always endangered by flood. The farmland patches were not symmetrically distributed along river, with 57.17% of farmland located on the left side of bank. The width of farmland patch presented an increasing trend, with a remarkable variation. The farmland patches were mainly strip-shape.

Agriculture↗
PubMed2001

[Use of autogenous cranial bone grafts for orbital floor reconstruction].

OBJECTIVE: To evaluate the effects of autogenous calvarial bone grafts on treatment of the patients with defect of orbital floor from facial trauma. METHODS: During a 5-year period from April 1994 to April 1999, 34 patients ranging in age from 16 to 68 years (twenty males and fourteen females), who presented with orbital floor defects associated with other facial fractures were reconstructed by autogenous calvarial bone grafts. The surgical approach to the orbital floor involved a transconjunctival incision in 31 patients and a subciliary incision in 3 patients. After the orbital floor exploration, the bone graft was harvested through the coronal incision in 29 patients and the parietotemporal region incision in 5 patients. The bone graft was then fashioned to the appropriate size and configuration and fixed to the stable bone of the orbital floor with microplates or screws. RESULTS: The surgical incisions healed well with a minimal scar. There were no infection, extrusion or other complications associated with autogenous calvarial bone graft. There were no cases of optic neuropathy, diplopia and enophthalmos. There was no morbidity in donor sites. One patient had slight ectropion, which lasted three months and became inconspicuous in six months. 8 cases with hypoesthesia of the infraorbital region returned the sensory function within 6 months. 6 patients with enophthalmos were partly corrected. The follow-up period ranged from 6 months to 5 years. CONCLUSION: The orbital floor defects should be managed by early exploration to avoid later complications. The sequel, such as enophthalmos and dystopia or diplopia are much more difficult to correct after bony union. A vast array of autogenous and alloplastic materials have been used to reconstruct the defect of orbital floor. Autogenous bone graft reduces the risk of infection and extrusion. Cranial bone graft produces less donor site morbidity compared with other sites, non-visible scar as the incision is placed within the hair-bearing skin and the conjunctiva. The membranous bone from the skull has been shown to undergo less resorption and greater graft volume survival as compared to endochondral bone of the iliac crest or rib. Skull bone is an ideal source of bone graft in orbital reconstruction.

Adolescent↗
PubMed2001

[Characteristics of nitrobenzene containing wastewater catalytic oxidation degradation by Fenton reagent].

Through the alteration of the concentration of catalyst and oxidant, the rulers and dynamics of nitrobenzene oxidized by Fenton reagent in different concentrations were studied. The correlativity of the reaction time and relatively remain nitrobenzene was analyzed by the unitary linear regress equation. The result of the analysis proves that the coefficient was over the critical constant. The oxidation of nitrobenzene by Fenton reagent was in conformity with first-order dynamics model and the reaction rate constant was got at the same time. The idea, using the complex of Fe as the catalyst replacing Fe2+ in the Fenton Reaction, not only got a higher reaction velocity and efficiency, but also had a distinct exclusive to the degradation of nitrobenzene. The remove velocity of nitrobenzene was improved from 17.48 mg/(L.min) to 71.22 mg/(L.min), the remove rate in 5 minutes was from 9.74% to 91.79%. The nonhomogeneous catalyst made by the artificial zeolite with Fe-complex adsorbed had the same catalyzing behavior. In addition, ultraviolet radiation can also improves the Fenton reaction to some degree. These research works could demonstrate the good application potentiality of Fenton reagent in treating wastewater.

Catalysis↗
PubMed2001

[Genetic epidemiology and HLA survey of primary hemochromatosis among Chinese Miao ethnic].

OBJECTIVE: To evaluate the inheritance modes and the genetic factors of primary hemochromatosis on its etiology among throngs of Chinese Miao nationality in causing the disease and to study the relation between the relevant susceptible gene and HLA linkage. METHODS: To investigate of the genetic epidemiology among some throngs of pure Miao nationality in western Human and the neighbouring areas was carried out and analysis of identical HLA haplotype and Lods was made. RESULTS: The population morbidity of this disease in this area is 0.48%. Twenty-four patients found in four families had high plasma glucose levels, and apparently high serum total iron and serum transferrin. The prevalence of hemochromatosis was 44.45% by analysis on the first degree and second degree relatives of the 24 patients. The individual marking of HLA ranges from locus A1, A2 to A3. CONCLUSION: HLA haplotype shows obvious deviation from random distribution, which indicates that there exists linkage between HH pathogenic gene and HLA. The results of genetic analysis in this disease group suggest that hemochromatosis is an autosomal dominant inheritance but not autosomal recessive inheritance disease.

Adolescent↗
PubMed2001

The effect of space radiation on the induction of chromosome damage.

To obtain information on the cytogenetic damage caused by space radiation, chromosome exchanges in lymphocytes from crewmembers of long-term Mir missions, and a shorter duration shuttle mission, were examined using fluorescence in situ hybridization. A significant increase in chromosomal aberrations was observed after the long duration flights. The ratio of aberrations identified as complex was higher post-flight for some crewmembers, which is thought to be an indication of exposure to high-LET radiation. Ground-based studies have shown that the frequency of aberrations measured post-flight could be influenced by a mitotic delay in cells damaged by high-LET radiation and this effect could lower biological dose estimates. To counteract this effect, prematurely condensed chromosome (PCC) spreads were collected. Frequencies of aberrations in PCC were compared with those in metaphase spreads.

Aerospace Medicine↗