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Biomedical subjects

B Hu

Publications and source records attributed to B Hu.

At least 145 records · Page 8Linked to original sources
PubMed1999

Fragments from actin binding protein (ABP-280; filamin) insert into reconstituted lipid layers.

Previous computer analyses suggested two possible lipid binding sites, residues 49-71 and 131-155, of the primary amino acid sequence on ABP-280 (filamin), which could facilitate membrane attachment/insertion. We expressed these regions as fusion proteins with schistosomal GST and investigated their interaction with mixtures of zwitterionic (dimyristoyl-l-alpha-phosphatidylcholine, DMPC) and anionic (dimyristoyl-l-alpha-phosphatidylglycerol, DMPG) phospholipids in reconstituted lipid bilayers by differential scanning calorimetry (DSC). Using vesicles of mixed DMPC/DMPG with increasing fusion protein concentrations, we established in calorimetric assays a decrease of the main chain transition enthalpy, DeltaH, and a shift in chain melting temperature. This is indicative of the insertion of these fragments into the hydrophobic region of lipid membranes. We confirmed these findings by the film balance technique using lipid monolayers (DMPG). The binding judged from both methods was of moderate affinity.

Amino Acid Sequence↗
PubMed1999

Genotoxicity of water samples from Dianchi lake detected by the Vicia faba micronucleus test.

Dianchi Lake covers about a 300 km2 area. Kunming city on the edge of the lake is surrounded by industrial establishments. Farm land surrounds the remaining areas of the lake. The lake water is polluted by the Kunming city municipal sewage from 3 million inhabitants, the industrial effluent and farm runoff. Water samples were collected from 12 sites along the shore of the lake during the dry (May) and rainy (August) seasons for genotoxicity testing with the Vicia micronucleus assay during the year 1995. Genotoxicity in terms of micronuclei (MCN) frequencies in the root tip cells of Vicia showed a consistent elevated frequency of MCN over the control sample at the 0.05-0.01 levels of significance in both seasons. The MCN frequencies of sites A (Daguanhe), B (Gaoqiao) and C (Xiyuan) were 3.5-4 times as high as the control values (5.25/1000 cells) in the dry season. In the rainy season, the MCN frequencies of water samples from most of the 12 sites were relatively lower than those of the dry season except sites J (Haikou), and K (Kunyang). The average MCN frequency of the dry season samples was 14.97 per 1000 cells and that of the rainy season samples was 12.24 per 1000 cells while the average control value was around 5.00/1000 cells.

Biological Assay↗
PubMed1999

Tradescantia bioassays for the determination of genotoxicity of water in the Panlong River, Kunming, People's Republic of China.

The Panlong river passes through Kunming City and receives a large quantity of municipal sewage and wastewater from industrial effluent. Along the river, 20 sites were selected to collect water samples to assess the genotoxicity using two Tradescantia assays, the micronucleus (Trad-MCN) and the stamen-hair-mutation (Trad-SHM) assays. The lowest frequencies in the Trad-MCN assay and the Trad-SHM assay are 3.19 MCN/100 tetrads and 1.32 M/1000 stamen hairs, respectively. In the water samples obtained from the Songhua Reservoir, the MCN frequencies and mutation rates are not statistically significantly different from the data found for the negative control (2.49 MCN/100 tetrads and 0.71 M/1000 stamen hairs). Among the other water samples, 19 in Trad-MCN assay and 17 in Trad-SHM assay show significantly higher genotoxicity than the control. The highest genotoxicity was in samples No. 19 for the MCN assay (8.73 MCN/100 cells), over three times higher than the negative control, and in sample No. 11 for the SHM assay (4.30 M/1000), six times higher than the negative control, and were about the same as for the positive control (10.0 mg/l NaN3, 9.28 MCN/100 tetrads and 7.44 SHM/1000 stamen hairs), respectively. The peak frequencies for the Trad-MCN assays were observed in the water samples obtained from the sites that were near industrial and municipal wastewater that ran into the river as effluent. In general, the frequency of MCN and SHM mutations increased where the river passed through Kunming. The Trad-MCN assay seemed more sensitive than that of the Trad-SHM assay in detecting genotoxicity of the river water pollution.

Biological Assay↗
PubMed1999

Biochemical and immunologic comparison of virus-like particles for a rotavirus subunit vaccine.

A parenterally administered rotavirus vaccine composed of virus-like particles (VLPs) is being evaluated for human use. VLPs composed of bovine VP6 and simian VP7 (SA11, G3) proteins (6/7-VLPs) or of bovine VP2, bovine VP6, and simian VP7 (SA11, G3) proteins (2/6/7-VLPs) were synthesized and purified from Sf9 insect cells co-infected with recombinant baculoviruses. 6/7- and 2/6/7-VLP administered parenterally (i.m.) in mice had comparable immunogenicity, but the 2/6/7-VLPs were more homogeneous and stable. The inclusion of the VP2 capsid contributed to particle formation and stability. The adjuvant QS-21 significantly enhanced the immunogenicity of 2/6/7-VLPs over A10H or saline alone. Equivalent serum neutralizing antibody responses were induced over the range of 1-15 microg/dose of 2/6/7-VLPs administered with the range of 5-20 microg/dose of QS-21. The immunogenicity of 2/6/7-VLPs and inactivated SA11 virus were comparable. 2/6/7-VLPs are a promising candidate for a parenterally delivered rotavirus subunit vaccine.

Adjuvants, Immunologic↗
PubMed1999

Expression of p75 neurotrophin receptor in the injured and regenerating rat retina.

The low affinity neurotrophin receptor (p75) has been suggested to be involved in apoptosis after neuronal injury. The tempo-spatial expression of p75 in the axotomized and regenerating retinas has not yet been determined. We examined the expression of p75 in the RGCs of these retinas using 192-IgG immunohistochemistry. The failure to detect p75 immunoreactivity on retrogradely fluorogold (FG)-labeled retinal ganglion cells (RGCs) in axotomized and regenerating adult retinas indicated that p75 was not expressed on RGCs. The low affinity p75 receptor was mainly localized on the Muller cell processes identified with vimentin antibody. Since p75 is not present in RGCs, the proposed pro-apoptotic role of p75 involved in the RGC death after optic nerve injury is unlikely to occur in rats.

Animals↗
PubMed1999

Skeletal effects of constant and terminated use of risedronate on cortical bone in ovariectomized rats.

To study the skeletal effects of continual and terminated use of risedronate treatment on cortical bone in ovariectomized (Ovx) rats, we used risedronate (Ris), 5 microg x kg(-1), by subcutaneous injections, twice per week. The middle part of the tibial shafts (Tx) were processed undecalcified for quantitive bone histomorphometry. Cortical bone and the marrow areas of the tibial shaft did not change in either sham-Ovx or Ovx rats during the 150-day experimental period. Continued administration of Ris for 150 days decreased the marrow area and increased the percentage of cortical area compared with the matching sham and Ovx group. A decrease in bone formation indices in both periosteal and endocortical surfaces of Tx in sham-operated rats between the age of 5 and 8 months was seen. Ovariectomy increased the percentage of labeled perimeter in the periosteal area, and markedly increased the percentage of eroded perimeter in the endocortical surface compared with sham control groups in 81 and 150 days. Bone formation indices of Ris treatment were increased in periosteal surfaces, and percentages of eroded perimeter were decreased more in endocortical surfaces in 150 days than in the matching sham and Ovx groups. These data matched our static data, which showed a significantly increased percentage of cortical bone area and decreased percentage of marrow area. These bone gains were not maintained in the 90-day Ris withdrawal group. For cancellous bone, the 60-day Ris-treated high bone mass was maintained in the withdrawal group and not maintained in Ris continmuously treated group. These results indicate the effects of constant and terminated use of Ris in cortical bone were different from those in trabecular bone in the proximal tibial metaphysis.

Animals↗
PubMed1999

Expression of tau proteins and tubulin in extraskeletal myxoid chondrosarcoma, chordoma, and other chondroid tumors.

Tau proteins are microtubule-associated proteins required for the polymerization of tubulin. The abnormal accumulation of tau proteins in neurofibrillary tangles is a well-known phenomenon and has been studied extensively. However, the role of tau protein in chondroid tissue and its neoplasia is unknown. In the present study, 2 extraskeletal myxoid chondrosarcomas (EMCs), 6 chordomas, 6 chondrosarcomas, 3 myxoid chondrosarcomas of bone, 2 osteochondromas, 6 chondroblastomas, and 2 nonneoplastic adult articular cartilages were immunostained with monoclonal antibodies against tau proteins and tubulin. The results showed that the coexpression of tau proteins and tubulin was present only in EMCs (2/2) and chordomas (4/6). Although tubulin was detected in chondroblastomas (5/6), osteochondromas (2/2), chondrosarcomas (5/6), and myxoid-chondrosarcomas of bone (3/3), tau expression was absent in these tumors. The perichondrial chondroblasts but not chondrocytes from nonneoplastic articular cartilage also localize tau and tubulin with a much weaker staining intensity. The results mainly demonstrate that there is frequent expression of tau proteins in some microtubule-rich neoplasms, such as EMC and chordoma. The different immunostaining pattern of tau proteins between chordoma and myxoid chondrosarcoma of bone may be useful in the differential diagnosis, especially when both neoplasms occur in the base of skull.

Adult↗
PubMed1999

Resonant activations for a fluctuating barrier system driven by dichotomous noise and Gaussian white noise.

We consider the escape over a fluctuating barrier in the presence of a dichotomous noise and a Gaussian white noise. It is shown that the mean first passage time (MFPT) over the fluctuating barrier displays two resonant activations. One is the resonant activation of the MFPT as a function of the flipping rate of the fluctuating potential barrier; the other is the resonant activation of the MFPT as a function of the transition rate of the dichotomous noise. In addition, we find that the dichotomous noise can weaken the former resonant activation, but enhance the latter one. By further study, we find that, when the fluctuating potential barrier is driven by two or more dichotomous noises, there are three or more resonant activations.

Journal Article↗
PubMed1999

Cellular automaton models of driven diffusive Frenkel-Kontorova-type systems.

Three cellular automaton models of increasing complexity are introduced to model driven diffusive systems related to the generalized Frenkel-Kontorova (FK) models recently proposed by Braun et al. [Phys. Rev. E 58, 1311 (1998)]. The models are defined in terms of parallel updating rules. Simulation results are presented for these models. The features are qualitatively similar to those models defined previously in terms of sequentially updating rules. Essential features of the FK model such as phase transitions, jamming due to atoms in the immobile state, and hysteresis in the relationship between the fraction of atoms in the running state and the bias field are captured. Formulating in terms of parallel updating rules has the advantage that the models can be treated analytically by following the time evolution of the occupation on every site of the lattice. Results of this analytical approach are given for the two simpler models. The steady state properties are found by studying the stable fixed points of a closed set of dynamical equations obtained within the approximation of retaining spatial correlations only up to two nearest-neighboring sites. Results are found to be in good agreement with numerical data.

Journal Article↗
PubMed1999

Escape over a fluctuating barrier with additive and multiplicative noise.

The mean first passage time (MFPT) over the fluctuating potential barrier is investigated in the presence of additive and multiplicative noises. It is shown that the MFPT over the fluctuating potential barrier displays a resonant activation (RA). The effect of the additive and multiplicative noises and the correlation between them on the RA is that the additive and multiplicative noises can weaken the RA; but the correlation between them can enhance it. The susceptibility of the RA to the multiplicative noise is far larger than that to the additive one. In addition, we find that the transition rate (i.e., the inverse of the MFPT) over the fluctuating potential barrier can be suppressed by the positive correlation and show a minimum as the function of the noises' strengths.

Journal Article↗
PubMed1999

Conformational changes in simian virus 40 rearranged regulatory regions: effects of the 21-base-pair promoters and their location.

Simian virus 40 (SV40) is an excellent model system for investigating the cis- and trans-acting factors involved in eukaryotic DNA replication because it uses host enzymes, with the exception of the virus-encoded T-antigen (T-ag), to replicate its genome. Although its origin of replication (ori) is essential for DNA replication, there are transcriptional promoters and enhancers that affect DNA replication efficiency. T-ag binds to sites I to III within and around ori with different affinities and induces structural changes. We were interested in determining if the position of the promoters relative to ori influences the binding of T-ag to these regions. Furthermore, we characterized the DNA structural changes that occur as a result of protein binding when the promoters are absent and also when the promoters are moved from their wild-type position upstream of ori to a position downstream of ori. Using sequence- and conformation-specific chemical probes, our data indicate that (i) the conformation of site I is influenced by T-ag binding and by flanking sequences, (ii) the conformation of the promoters after T-ag binding is dependent on their location, and (iii) unwinding of ori is influenced by the location of the promoters and their presence or absence. These differences in DNA conformation may help explain decreases in relative DNA replication efficiency that occur when the promoters are absent or located downstream of ori.

Animals↗
PubMed1999

Effects of target area and letter complexity on event-related potentials and reaction time.

The idea that an area of the visual field stimulated by a recognizable image activates a corresponding area of neural tissue that generates the recognition potential (RP) was examined. Sixteen subjects detected targets in a stream of non letter character arrays. The targets were one or five rows of a repeated letter (O or G). RT was less for the larger targets and less for O than for G. RP latency differences agreed with the RT differences. RP amplitude was substantially greater for large than for small targets and moderately larger for G than for O. P3 amplitude showed a different relationship. The observed amplitude-latency relationships indicated that differences in stimulus strength were not responsible for the greater RP evoked by the larger targets. The results strengthened the neural area explanation for RP amplitude modulation by the area of the visual fields impinged on by recognizable images.

Adult↗
PubMed1999

[An investigation of small marker chromosome in eight Turner syndrome patients by fluorescence in situ hybridization and DNA analysis].

OBJECTIVE: To direct genetic counseling and identify the origin of small marker chromosome in patients with Turner syndrome stigmata. METHODS: The specific primer on the sex determining region on Y (SRY) and biotin labeled X- and Y-chromosome DNA probes were utilized in the analysis of sex chromosome-derived markers. The PCR product from the amplification was detected on agarose gel, and fluorescence in situ hybridization (FISH) was conducted to metaphase chromosome. RESULTS: In 8 patients who had a small marker chromosome, five markers were derived from the X chromosome and three from the Y chromosome. Two patients with a Y-derived marker were determined by Y-chromosome probe as well as by SRY sequences amplification. One patient with a Y-derived marker was only demonstrated by FISH. CONCLUSION: The findings of this study demonstrate successfully the value and necessity of FISH utilizing DNA probes combined with specific amplification on SRY gene in the identification of sex chromosome marker. Such identification is important not only for clinical care, but also for understanding phenotype-karyotype correlations.

DNA-Binding Proteins↗
PubMed1999

[Analysis of prenatal diagnosis for 120 cases of beta-thalassemia].

OBJECTIVE: To analyse the results of prenatal gene diagnosis of beta-thalassemia. METHODS: By using the reverse dot blot method with an allele specific oligonucleotide probe(ASO/DRB). RESULTS: In 120 cases of prenatal gene diagnosis, there are 30 of normal fetal; 63 of beta-thalassemia heterozygotes; 26 of beta-thalassemia homozygotes or dual heterozygotes; one of no diagnosis because the beta mutated gene can not be detected in one side of the parent. CONCLUSIONS: Acording to the follow-up studies, the babies unconcordance with prenatal diagnosis have not been found, the accuracy rate being 100%. Amniotic fluid specimen of the middle stage of pregnancy is the best for detection.

Amniocentesis↗
PubMed1999

[A review on TCM literatures of Ming - Qing periods].

A systematic review is made on TCM literatures of Ming - Qing periods on the following aspects, including clinical literature, popularization, variorum, literature studies and features of outward appearance. The causes of the overall development of TCM literatures, and its promotion on TCM scholarship are also discussed. It is pointed out that the TCM literatures, being the main body of TCM literature as a whole, should become the main goal for modern studies. The books mentioned here are arranged in chronological order of its writing dates.

China↗
PubMed1999

[Gastric colonization and its effect on pathogenesis of nosocomial pneumonia].

OBJECTIVE: To study the gastric colonization and its effect on development of nosocomial pneumonia (NP). METHODS: We investigated the microorganism (mainly pathogens) constitution, isolating sequences and risk factors in gastric, oropharyngeal and lower respiratory tract flora. Microbiologic cultures of serially taken samples of gastric aspirates, oropharyngeal swabs and bronchoalveolar lavages (BALs) or sputums were performed at the time of ICU admission and subsequently every morning in 52 surgical patients with nasogastric tube. Etiologic diagnosis of NP was based on quantitative cultured of BAL or sputum. Sequences of colonization were examined by comparing isolates of the same species with concordance of minimum inhibitory concentration values to 12 antibiotics. RESULTS: A total of 237 pairs of gastric and oropharyngeal specimens were taken. 77 strains of gram- negative bacilli (GNB) isolated from stomach, more than the number of GNB isolated from oropharynx (51 strains), P = 0.007. Comparing the species, Enterobacteriaceae isolated from stomach was much more than that from oropharynx (46 vs 24 strains, P = 0.004), and in most instances stomach colonization was before oropharynx colonization one to two days. Isolating rates of Pseudomonas were the same in both kinds of specimens. On contrast, Acinetobacter colonization in oropharynx was much more than that in stomach (10 vs 3 strains, P = 0.049). Risk factors for GNB colonization in stomach included increased gastric pH, medications inhibiting gastric acid secretion (such as cimitidine, omeprazole), and systemic use of cephalosporins. 10 patients developed NP and 5GNB (Enterobacter cloacae 2, Pseudomonas aeruginosa 2, Acinetobacter anitratum 1) isolated from BAL or sputum in 4 of 10 patients. A sequence of colonization from the stomach to the respiratory tract leading to pneumonia was observed in 3 patients. CONCLUSIONS: It was suggested that the stomach is likely to be an important source of pathogens leading to NP, especially Enterobacteriaceae pneumonia.

Adult↗
PubMed1999

[Extensive transbasal approach for removal of tumours in the nasal, sphenoid and clival regions].

OBJECTIVE: To improve operative results of removal of the tumors in midline cranial base and the reconstruction of defect at frontal base through modification of the operative approach and techniques. METHODS: Extensive transbasal approach was used in 15 patients with tumours in the nasal, sphenoid and clival regions. RESULTS: The tumor was removed in 10 patients, near totally removed in 4 and partial removed in 1. The operative results of all patients were excellent except an elderly patient with mild operative morbidity. CONCLUSIONS: The procedure we used expand the operative indications for the tumors situated at the midline cranial base and improve the operative results. The procedure has advantages such as wide operative space, reliable reconstruction of the frontal base, and no severe complications.

Adult↗