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Biomedical subjects

B Hu

Publications and source records attributed to B Hu.

At least 127 records · Page 7Linked to original sources
PubMed2000

A promoter region binding protein and DNA gyrase regulate anaerobic transcription of nifLA in Enterobacter cloacae.

Our work provides evidence that a sequence characteristic of FNR binding sites, when interacted with by a trans-acting factor, activates anaerobic transcription of the nifLA operon in Enterobacter cloacae. DNA gyrase activity has been found to be important for the anaerobic transcription of the nifLA promoter. Our results suggest that anaerobic regulation of the nifLA operon is mediated through the control of the promoter region-binding trans-acting factor at the transcriptional level, while DNA supercoiling functions in providing a topological requirement for the activation of transcription.

Anaerobiosis↗
PubMed2000

Analysis of related factors in complications of stereotactic radiosurgery in intracranial tumors.

OBJECT: To investigate the related factors in complications of stereotactic radiosurgery for intracranial tumors. METHODS: A retrospective review of 146 patients with intracranial tumors treated with stereotactic radiosurgery was conducted. Sixty-five patients received single-dose treatment and the rest received fractionated stereotactic radiosurgery. Ninety-five patients received conventional radiotherapy in the meantime. RESULTS: Follow-up period was 18-54 months. Follow-up rate was 92.5% and 39 patients (26.7%) had different complications. The Cox statistics showed that target volume, target peripheral dose, target maximal dose, and ratio of maximal dose to peripheral dose are related to the complications. Conversely, neither type of tumor disease, gender, radiation schedule with or without conventional radiotherapy, target minimal dose, nor ratio of target peripheral isodose volume to target volume were found to be related to complications. CONCLUSION: Target volume and dose are the major factors causing complications, and the optimization of the therapeutic planning can play a significant role in reducing them.

Brain Edema↗
PubMed2000

The recognition potential and reversed letters.

The effect of letter reversal on the detection of Gestalt patterns was investigated by recording a short latency brain wave response known as the recognition potential (RP). The native language of 12 subjects was English. It was Chinese for 12 others. Three hypotheses were tested. (1) Strings of identical characters displayed on a background of dissimilar characters will evoke the RP. (2) RP latency will be less for normal letter targets than for reversed letter targets. (3) The letter reversal effect will be greater for subjects having longer experience with alphabetical characters. The hypotheses were confirmed. Similar effects of letter reversal were also found for longer latency electrophysiological responses and for behavioral reaction time (RT). The RP latency difference equaled the RT difference. This suggested that letter specific processes operated rapidly, not later, than the latency of the RP, and any subsequent processing had no differential effect on RT.

Adult↗
PubMed2000

A telemedicine management model based on message-trigger service.

A telemedicine system model, based on a message-trigger service, is described. This model distributes system applications on multiple computers and establishes a communication platform to exchange messages among all applications. By broadcasting event messages, an application is able to trigger a set of local and remote services. At the same time, a protocol for message exchange is proposed to fulfill cooperation of applications. To validate the model, a teleconsultation system is designed. The results indicate that the model has good compatibility and that the characteristics are easy to implement.

Computer Communication Networks↗
PubMed2000

[QTLs and epistasis underlying rice (Oryza sativa L.) panicle length in different genetic background and environments].

A double haploid (DH) population and a recombinant inbred (RI) population derived from a cross between a japonica male parent Azucena and indica female parents, IR64 and IR1552 respectively, were used in both field and pot experiments for detecting QTLs and epistasis for rice panicle length in different genetic background and different environments. Panicle length (PL) was measured at maturity. QTLs for PL were detected using single marker analysis and interval mapping. Epistasis effects on the trait were also analyzed. Nine QTLs were detected in DH population, including 5 QTLs detected from field experiment and 4 from pot experiment, among them 3 QTLs mapped on chromosomes 1 and 4 were identified in both field and pot experiments. No significant epistasis effect was detected for PL. Four QTLs were detected in RI population, among them 2 from field condition and 2 from pot experiment. 6 pairs of epistasis loci were detected in RI population. One QTL mapped on chromosome 4 and two pairs of epistatic loci were detected in both field and pot experiments. One QTL on chromosome four was identified in both populations, and one marker locus RG323 on chromosome one was involved in additive effect in DH population, but epistasis effects in RI population.

Chromosome Mapping↗
PubMed2000

Hemodynamic assessment of ischemic stroke with near-infrared spectroscopy.

OBJECTIVE: To validate near-infrared cerebral topography (NCT) as a practical tool in tracing the regional hemodynamic changes during normal ischemic stroke model of rat. METHOD: Middle cerebral artery occlusion (MCAO) and photosensitizer induced intracranial infarction model of rat were established. The geometric shape and infarction area were measured by NCT, functional magnetic resonance imaging (fMRI), and TTC stained anatomical imaging techniques. RESULT: In photosensitizer induced infarction model, the correlation between anatomical infarct area and NCT image area for infarct focus were r = 0.897 for 24 h group (P < 0.05) and r = 0.906 for 2 months group (P < 0.01), respectively. The correlation between anatomical infarction area and NCT image area for infarct focus were r = 0.820 for normothermia group (P < 0.05) and r = 0.851 for hypothermia group (P < 0.05), respectively. The correlation between fMRI and NCT image area for infarction focus were r = 0.874 for normothermia group (P < 0.05) and r = 0.782 for hypothermia group (P < 0. 05), respectively. CONCLUSION: Measurement with NCT for infarction focus matched well with fMRI and anatomic sample in rats. NCT technique might be a practical tool for short-term prediction of stroke and the rehabilitation after stroke in real time.

Animals↗
PubMed2000

[Microsurgical treatment of large or giant aneurysms in anterior circle of Willis].

OBJECTIVE: To improve the operative results in large or giant aneurysms of the anterior circle Willis. METHODS: Retrospective analysis was performed on 28 patients with large or giant aneurysms of the anterior circle Willis after operation. Three-D CT angiography was used to detect and delineate aneurysm preoperatively. Improved operative technique included cranial base approach, temporary artery occlusion, intra-aneurysm decompression, obliteration of aneurysm with multiple clips, stepwise coagulation clipping and resection of aneurysms. RESULTS: Good results were noted in 24 patients (85.7%), fair in 2, and poor in 1. One patient died, but no patient with Hunt and Hess 0-III grade died. CONCLUSIONS: Three-D CT angiography is useful in delineating the shape, size, neck of aneurysms, and their relation to near arteries and to cranial base structures. These are helpful to improve operative results of large or giant aneurysms of the anterior circle of Willis.

Adult↗
PubMed2000

[Study on the epidemiological features of Kawasaki disease in Jiangsu].

OBJECTIVE: To investigate the incidence of Kawasaki disease and epidemiological characteristics in Jiangsu province. METHODS: Questionnaire and diagnostic guidelines for Kawasaki disease with color - printed photographs of typical clinical symptoms were sent to all county hospitals with pediatric beds. All the in - patients with Kawasaki disease hospitalized from January, 1993 to December, 1997 were studied regarding age, sex, season of illness, cardiac sequelae, outcome etc. RESULTS: There were 509 cases (329 males and 180 females) diagnosed with 489 cases (96%) clinically typical. The incidence of the 5 - year period was averaged 2.53 per 100,000 children under 5. The number of male patients with Kawasaki disease was higher than that in female. The age peak of incidence was between 6 month and 2 - year olds. 13.6% of all cases developed cardiac sequelae which mostly occurred in males and in those younger than 2 years of age. There was one patient recurred among total patients reported (recurrence rate 0.2%) and 2 patients died (fatality rate 0.4%). CONCLUSION: The epidemiological characteristics of Kawasaki disease in Jiangsu province were similar to those in Japan in sex, season distribution and cardiac sequelae. The number of patients in male was higher than in female. Patients were more commonly seen in spring than in winter. However, the incidence rate in Jiangsu was significantly lower than that in Japan and the age peak was between 6 month and 2 years old.

Adolescent↗
PubMed2000

[An experimental study on the effect of positional asphyxia on cardiac and pulmonary functions].

The purpose of the study is to explore the effect of positional asphyxia on cardiac and pulmonary functions and its role in causing death. respiration, pulmonary artery pressure and cardiac output were measured by inserting the swan-ganz into the pulmonary artery from the femoral vein. Results showed that: (1) the respiration was stable before hanging, getting faster during hanging, and becoming irregular at the terminal stage of hanging; (2) the pulmonary artery pressure increased significantly during and at the terminal stage of hanging as compared with that before hanging; (3) the cardiac output was stable before and during hanging, but decreased significantly at the terminal stage of hanging. It is concluded that hanging may cause respiratory imbalance and hypoxia, resulting in cardiac and pulmonary dysfunction. The death caused by hanging belongs to respiratory death, the characteristic of which is primary respiratory arrest followed by secondary cardiac arrest.

Airway Obstruction↗
PubMed2000

[Immunohistochemical study of basic fibroblast growth factor of early myocardial infarction].

The expression of basic fibroblast growth factor (bFGF) was first studied in 61 cases of early myocardial infarction. The results revealed that all 24 cases of proven infarcts was positive in nuclei of myocardium and vascular endothelium, and that some was positive in cytoplasm, especially in myocardium around the border zone of infarction. Of 21 suspected infarcts cases, 17 showed strong positive and 4 mild positive. In the control group of 16 samples, only 3 was mild positive sparsely in nuclei of myocardium and vascular endothelium. PI of control group was significantly lower than that of proven and suspected infarcts (P < 0.01). There was no significant difference between PI of proven infarcts and suspected infarcts (P > 0.05). These findings suggest that SABC-bFGF method could be used for morphologic diagnosis of early myocardial infarction of sudden cardiac death.

Autopsy↗
PubMed2000

[The regulation effects of growth factors on the procollagen gene expressions of human mandibular condylar cartilage cells].

OBJECTIVE: At the early stage of osteoarthrosis (OA) and joint damage, the cartilage cells proliferation increases dramatically, but this repair process is finally replaced by the progressive destruction of the cartilage. The reason, in accordance to the latest research, is the abnormal phenotype of the involved cartilage cell. This result suggests that the regulation of cartilage cell phenotype may be an effective way in the treatment of OA and other cartilage destructive diseases. In this study, the effects of transforming growth factor-beta(TGF-beta), insulin-like growth factor-I (IGF-I) and basic fibroblast growth factor (bFGF) on collagen expression of human mandibular condylar cartilage cells was investigated. METHODS: Chondrocytes were isolated from human fetus by enzymatic method. The second passage of the cells was used in this study. They were cultured in DMEM medium supplemented with 20% newborn calf serum (NCS). After the cells reached confluence, the medium was replaced by DMEM containing 0.4% NCS. Then the cells were exposed to different growth factors including IGF-I (10 ng/ml), TGF-beta (5 ng/ml) and bFGF (50 ng/ml). The steady state mRNA levels of different samples were examined by slot-blot hybridization. The results were analysed by Student t test. RESULTS: IGF-I had the least effects on the mRNA levels of three kinds of procollagen (type I, type II and type III). On the other hand, bFGF and TGF-beta could inhibit the expression of type II collagen by 0.352 and 0.685 times comparing with the control groups separately. TGF-beta increased type I collagen expression. Besides, bFGF and TGF-beta also increased the value of type I collagen/type II collagen. None of the three kinds of growth factors had obvious effects on the expression of type III collagen. CONCLUSION: IGF-I can maintain the chondrocyte differentiated phenotype, while TGF-beta and bFGF have inhibitory effects.

Cells, Cultured↗
PubMed2000

[Biological effects of supplements on soil properties and the growth of Panax quinquefolium].

This paper suggests that the physical and chemical characteristics of soil in American ginseng field were greatly improved after utilization of supplement on soil. Compared with the contrast, the soil gravity ratio decreased from 0.812 g/cm3 to 0.715 g/cm3, while the soil porosity increased from 69.36% to 73.03%. These improvements are benefit for the growth of Panax quinquefolium. Biological observations show that the fresh weight of ginseng root enhanced 53.8%, and the content of total saponins in root enhanced 0.5%-1% (get to 8.28%).

Carbon↗
PubMed1999

Reduction of intracerebral hemorrhaging in a rabbit embolic stroke model.

OBJECTIVE: To study the effects of a spin trap agent and a CD18 antibody administered after stroke induction on intracerebral hemorrhaging. The drugs can prevent leukocyte adhesion. METHODS: A rabbit embolic stroke model that produces intracerebral hemorrhage was used. RESULTS: A time course study showed that hemorrhaging was grossly apparent in approximately 50% of the subjects at 5 hours and in 75% at 24 hours after embolization. MDL 101,002, a spin trap agent, administered IV 5 minutes after embolization, significantly decreased the volume of hemorrhage. It also improved the behavior score relative to vehicle-treated rabbits. The CD18 antibody tended to decrease hemorrhage volume. CONCLUSION: The beneficial effect of MDL 101,002 may be caused by inhibition of free radical injury to brain tissue, thereby protecting brain microvessel integrity. Acute therapy for intracerebral hemorrhage may be feasible.

Animals↗
PubMed1999

[Relationship between homocysteine-induced apoptosis and teratogenesis in developing avian embryo].

It has been hypothesized that homocysteine(HCY) can induce apoptosis at the organogenesis-stage of chick embryos and which can be the relationship between HCY and congenital defects of neural tube and heart. Exogenous D, L-HCY (4-8 mumol/embryo) was injected into the place near brain and the yolk of the day 4 embryos. Then they were harvested 2 days later and examined by flow cytometry, histopathology, electronic microscope, in situ end labeling of DNA strand break and methylgreen-pyronine double staining. The change of plasma HCY level of day 10 embryos was also inspected by HPLC analysis. The HCY injected at different position of embryos could result in heart and neural tube defects, which included ectopia cardis, hydropericardium, endocardial cushion defect, encephalocele, microcephaly, abnormal flexions and so on. HCY could apparently disturb embryonic cell cycle, suppress the synthesis of DNA and RNA of embryonic cells. Excessive apoptotic cells in brain and heart were observed in HCY\|treatment groups. It was discovered that mitochondrial damage could be described as an early event in cellular apoptosis of chick embryos. After 8 mumol of HCY was placed on the inner shell membrance, there was an obvious increase of plasma HCY concentration with a peak value of 80.58 mumol/L in 120 min, and followed by declining. On the other hand, 5 micrograms of folic acid given simultaneously with HCY could sharply curtail the rise in plasma HCY. It is concluded that HCY is a cytotoxin, inducing over apoptosis of embryos in some areas, which is coincident with the pathologic changes of neural system and heart. These findings show that there is a close relationship among HCY, apoptosis and birth defect in developing chick embryos. Mitochondrial dysmorphosis may be an important early event of apoptosis in embryos after exposure to HCY.

Animals↗
PubMed1999

Mutants that alter the covalent structure of catalase hydroperoxidase II from Escherichia coli.

The three-dimensional structures of two HPII variants, V169C and H392Q, have been determined at resolutions of 1.8 and 2.1 A, respectively. The V169C variant contains a new type of covalent bond between the sulfur atom of Cys(169) and a carbon atom on the imidazole ring of the essential His(128). This variant enzyme has only residual catalytic activity and contains heme b. The chain of water molecules visible in the main channel may reflect the organization of the hydrogen peroxide substrates in the active enzyme. Two alternative mechanisms, involving either compound I or free radical intermediates, are presented to explain the formation of the Cys-His covalent bond. The H392Q and H392E variants exhibit 75 and 25% of native catalytic activity, respectively. The Gln(392) variant contains only heme b, whereas the Glu(392) variant contains a mixture of heme b and cis and trans isomers of heme d, suggesting of a role for this residue in heme conversion. Replacement of either Gln(419) and Ser(414), both of which interact with the heme, affected the cis:trans ratio of spirolactone heme d. Implications for the heme oxidation mechanism and the His-Tyr bond formation in HPII are considered.

Amino Acid Sequence↗
PubMed1999

p53 selective and nonselective replication of an E1B-deleted adenovirus in hepatocellular carcinoma.

An E1B gene-attenuated adenovirus (dl1520) has been proposed to have a selective cytolytic activity in cancer cells with a mutation or deletion in the p53 tumor suppressor gene (p53-null), a defect present in almost half of human hepatocellular carcinomas (HCCs). In this study, the in vitro and in vivo antitumor activity of dl1520 was investigated focusing on two human HCC cell lines, a p53-wild type (p53-wt) cell line and a p53-null cell line. dl1520 was tested for in vitro cytopathic effects and viral replication in the human HCC cell lines Hep3B (p53-null) and HepG2 (p53-wt). The in vivo antitumor effects of dl1520 were investigated in tumors grown s.c. in a severe combined immunodeficient mouse model. In addition, the combination of dl1520 infection with systemic chemotherapy was assessed in these tumor xenografts. At low multiplicities of infection, dl1520 had an apparent p53-dependent in vitro viral growth in HCC cell lines. At higher multiplicities of infection, dl1520 viral replication was independent of the p53 status of the target cells. In vivo, dl1520 significantly retarded the growth of the p53-null Hep3B xenografts, an effect augmented by the addition of cisplatin. However, complete tumor regressions were rare, and most tumors eventually grew progressively. dl1520 had no effect on the in vivo growth of the p53-wt HepG2 cells, with or without cisplatin treatment. The E1B-deleted adenoviral vector dl1520 has an apparent p53-dependent effect in HCC cell lines. However, this effect is lost at higher viral doses and only induces partial tumor regressions without tumor cures in a human HCC xenograft model.

Adenoviridae↗
PubMed1999

Association of the epithelial sodium channel with Apx and alpha-spectrin in A6 renal epithelial cells.

Recent molecular cloning of the epithelial sodium channel (ENaC) provides the opportunity to identify ENaC-associated proteins that function in regulating its cell surface expression and activity. We have examined whether ENaC is associated with Apx (apical protein Xenopus) and the spectrin-based membrane cytoskeleton in Xenopus A6 renal epithelial cells. We have also addressed whether Apx is required for the expression of amiloride-sensitive Na(+) currents by cloned ENaC. Sucrose density gradient centrifugation of A6 cell detergent extracts showed co-sedimentation of xENaC, alpha-spectrin, and Apx. Immunoblot analysis of proteins co-immunoprecipitating under high stringency conditions from peak Xenopus ENaC/Apx-containing gradient fractions indicate that ENaC, Apx, and alpha-spectrin are associated in a macromolecular complex. To examine whether Apx is required for the functional expression of ENaC, alphabetagamma mENaC cRNAs were coinjected into Xenopus oocytes with Apx sense or antisense oligodeoxynucleotides. The two-electrode voltage clamp technique showed there was a marked reduction in amiloride-sensitive current in oocytes coinjected with antisense oligonucleotides when to compared with oocytes coinjected with sense oligonucleotides. These studies indicate that ENaC is associated in a macromolecular complex with Apx and alpha-spectrin in A6 cells and suggest that Apx is required for the functional expression of ENaC in Xenopus epithelia.

Amino Acid Sequence↗