Biomedical subjects

D He

Publications and source records attributed to D He.

At least 55 records · Page 3Linked to original sources

PubMed2000

Sound absorption of cellular metals with semiopen cells.

A combined experimental and theoretical study is presented for the feasibility of using aluminum foams with semiopen cells for sound-absorption applications. The foams are processed via negative-pressure infiltration, using a preform consisting of water-soluble spherical particles. An analytical model is developed to quantify the dependence of pore connectivity on processing parameters, including infiltration pressure, particle size, wetting angle, and surface tension of molten alloy. Normal sound-absorption coefficient and static flow resistance are measured for samples having different porosity, pore size, and pore opening. A theory is developed for idealized semiopen metallic foams, with a regular hexagonal hollow prism having one circular aperture on each of its eight surfaces as the unit cell. The theory is built upon the acoustic impedance of the circular apertures (orifices) and cylindrical cavities due to viscous effects, and the principle of electroacoustic analogy. The predicted sound-absorption coefficients are compared with those measured. To help select processing parameters for producing semiopen metallic foams with desirable sound-absorbing properties, emphasis is placed on revealing the correlation between sound absorption and morphological parameters such as pore size, pore opening, and porosity.

Acoustics↗

PubMed2000

[Quantitative characteristics of rare and endangered Castanopsis kawakamii population].

In this paper, a new self-adaptive model for population growth, i.e. S = exp(alpha ln2(1 + ce-rt) + beta ln(1 + ce-rt) + gamma) was established, which combined Logistic, Smith, Gompertz, Gui-Lawson, Zhang-Logistic and Liu-Logistic models. Estimations with genetic algorithm showed that the new model was more suitable than other models to simulate the actual growth trend of Castanopsis kawakamii population.

China↗

PubMed2000

[Energy distribution of Phyllostachys pubescens ecosytem in north Fujian].

Based on the data obtrained from 40 Phyllostachys pubescens plots in Jianou City of Fujian Province, the distribution of energy was studied in this paper. The results showed that the energy contained in stems, branches and leaves, and underground parts of P. pubescens ecosystem were 4.2322 x 10(8) kJ.hm-2, 0.9230 x 10(8) kJ.hm-2 and 1.7643 x 10(8) kJ.hm-2, accounting for 61.32%, 13.11% and 25.57% of the total energy respectively.

China↗

PubMed2000

[An experimental study on physiotherapy for traumatic facial nerve injury].

OBJECTIVE: To investigate the effects of electric stimulation, iontophoresis and electric stimulation with iontophoresis therapy in treating traumatic facial nerve injury. METHODS: Fifty rabbits were used. All right buccal branch of facial nerve were injured. The rabbits were randomly divided into five groups and treated by different stimulation pattern: (a) electric stimulation group; (b) iontophoresis group; (c) iontophoresis with electric stimulation group; (d) routine therapy group; (e) control group. The histologic morphology, quantitative indices of nerve fibers and electroneurography(ENoG) indices were analyzed. RESULTS: (a) Iontophoresis with Vitamin B1 and Vitamin B12 improved the regeneration of facial nerve myelin sheath. And had the best effect among these groups. (b) Electric stimulation had great effect on axon regeneration. (c) The group of electric stimulation with iontophoresis therapy had the best comprehensive effect on the nerve injury. CONCLUSIONS: Both electric stimulation and iontophoresis have good effects on nerve regeneration, when they are used in combination, the best comprehensive effect will be expected.

Animals↗

PubMed2000

[Effect of Cordyceps sinensis on the Th1/Th2 cytokines in patients with Condyloma Acuminatum].

OBJECTIVE: To investigate the effect of cordyceps sinensis (CS) on the Th1/Th 2 cytokines and recurrence in patients with Condyloma Acuminatum (CA). METHOD: Double-antibody sandwich ELISA was used to study the serum level of IL-2 and IL-10 in 34 patients treated with CS(CS group) and 29 patients in control group. The recurrence rate of CA was observed. RESULT: After treated with CS, the serum levels of IL-2 and IL-10 significantly increased and decreased respectively (P < 0.05 or 0.01). No significant change occurred in control group. The recurrence times of CA in patients of CS group after electrocauterization were significantly lower than control group (P < 0.05). CONCLUSION: CS might recover the balance of Th1/Th2 cytokines and enhance Th 1 immune response in patients with CA, and reduced the recurrence of CA.

Adjuvants, Immunologic↗

PubMed1999

[Investigations on dermal contamination among workers exposed to terephthalic acid].

Forty-three workers exposed to terephthalic acid(TPA) were selected to study the dermal contamination of TPA and the load of TPA in urine. The results showed that there existed a double logarithmic correlation between dermal contamination of TPA and air TPA concentration and a a logarithmic correlation between urinary TPA and total inhaled TPA. Neither dermal TPA contamination nor total TPA exposure exhibited and dose-dependent relationship with urinary TPA. Based on this occupational epidemiology investigation, it was proved that the absorption of TPA is not mainly from dermal exposure.

Adolescent↗

PubMed1999

Effects of glucose and related substrates on the recovery of the electrical activity of gonadotropin-releasing hormone pulse generator which is decreased by insulin-induced hypoglycemia in the estrogen-primed ovariectomized rat.

We investigated the effect of glucose and its related substrates on the recovery of pulsatile luteinizing hormone (LH) secretion which was suppressed by insulin in estrogen-primed ovariectomized rats. We also examined the effect of glucose on the electrical activity of the gonadotropin-releasing hormone (GnRH) pulse generator which was suppressed by insulin. The intravenous (i.v.) injection of insulin (5 units/rat) suppressed the pulsatile LH secretion for 3 h in estrogen-primed ovariectomized rats. This suppressive effect of insulin on the LH secretion was rapidly reversed by the i.v. injection of glucose and mannose but not by the injection of lactate and saline. Fructose could recover the LH secretion suppressed by insulin, but took a longer time than glucose did. By monitoring the electrical activity of the GnRH pulse generator, we found that i.v. injection of insulin suppressed the pulsatile LH secretion by decreasing the activity of the GnRH pulse generator. Again, the i.v. injection of glucose, but not saline, immediately recovered the decrease in the electrical activity of the GnRH pulse generator. Fructose could recover the activity of the GnRH pulse generator, but it took a longer time than glucose did. We suggest that glucose availability, but not simply a metabolic state such as the ATP level, is an essential factor for maintaining the electrical activity of the GnRH pulse generator which is responsible for pulsatile LH secretion.

Animals↗

PubMed1999

HCA, an immunoglobulin-like adhesion molecule present on the earliest human hematopoietic precursor cells, is also expressed by stromal cells in blood-forming tissues.

We have previously shown that the HCA/ALCAM (CD166) glycoprotein, a member of the immunoglobulin family that mediates both homophilic and heterophilic cell-cell adhesion, via the CD6 ligand, is expressed at the surface of all of the most primitive CD38(-/lo), Thy-1(+), rho123(lo), CD34(+) hematopoietic cells in human fetal liver and fetal and adult bone marrow. In the present report we show that HCA is also expressed by subsets of stromal cells in the primary hematopoietic sites that sequentially develop in the human embryo and fetus, ie, the paraaortic mesoderm, liver, thymus, and bone marrow. Adult bone marrow stromal cells established in vitro, including those derived from Stro-1(+) progenitors and cells from immortalized cell lines, express HCA. In contrast, no HCA expression could be detected in peripheral lymphoid tissues, fetal spleen, and lymph nodes. HCA membrane molecules purified from marrow stromal cells interact with intact marrow stromal cells, CD34(+) CD38(-) hematopoietic precursors, and CD3(+) CD6(+) peripheral blood lymphocytes. Finally, low but significant levels of CD6 are here for the first time detected at the surface of CD34(+) rho123(med/lo) progenitors in the bone marrow and in mobilized blood from healthy individuals. Altogether, these results indicate that the HCA/ALCAM surface molecule is involved in homophilic or heterophilic (with CD6) adhesive interactions between early hematopoietic progenitors and associated stromal cells in primary blood-forming organs.

Adult↗

PubMed1999

A cluster of five cell wall-associated receptor kinase genes, Wak1-5, are expressed in specific organs of Arabidopsis.

WAK1 (wall-associated kinase 1) is a cytoplasmic serine/threonine kinase that spans the plasma membrane and extends into the extracellular region to bind tightly to the cell wall. The Wak1 gene was mapped and found to lie in a tight cluster of five highly similar genes (Wak1-5) within a 30 kb region. All of the Wak genes encode a cytoplasmic serine/threonine protein kinase, a transmembrane domain, and an extracytoplasmic region with several epidermal growth factor (EGF) repeats. The extracellular regions also contain limited amino acid identities to the tenascin superfamily, collagen, or the neurexins. RNA blot analysis with gene-specific probes revealed that Wak1, Wak3 and Wak5 are expressed primarily in leaves and stems of Arabidopsis. Wak4 mRNA is only detected in siliques, while Wak2 mRNA is found in high levels in leaves and stems, and in lower levels in flowers and siliques. A trace amount of Wak2 can also be detected in roots. Wak1 is induced by pathogen infection and salicylic acid or its analogue INA and is involved in the plant's response, and Wak2, Wak3 and Wak5 also can be greatly induced by salicylic acid or INA. The WAK proteins have the potential to serve as both linkers of the cell wall to the plasma membrane and as signaling molecules, and since Wak expression is organ-specific and the isoforms vary significantly in the cell wall associated domain this family of proteins may be involved in cell wall-plasma membrane interactions that direct fundamental processes in angiosperms.

Amino Acid Sequence↗

PubMed1999

Construction and analytical application of ion-selective piezoelectric sensor for atropine sulfate.

The method describes the use of a piezoelectric quartz crystal (PQC) as a substitute for ion-selective electrodes. The approach is feasible when the membrane materials are electrically non-conductive and membrane potential measurements are consequently not possible. An ion-selective piezoelectric sensor sensitive to atropine sulfate was constructed by coating a PVC membrane containing activant on one the side of a PQC. On the basis of selective adsorption of atropine ions across the modified film and the sensitive mass response of PQC, the method exhibits a sensitive, rapid response and is easy to operate without pretreatment of the sample. The logarithm of the frequency shift gave a linear relationship with the logarithm of atropine sulfate concentration in the 1.0 x 10(-8)-1.0 x 10(-3) M range with a detection limit of 5.0 x 10(-9) M at pH 7.0. Recoveries were from 98.7-102.2%. Two activants, atropine tetraphenylborate and atropine dipicrylaminate, were synthesized and investigated. Influencing factors were also examined and optimized. The results for real samples obtained by the proposed method agreed with those obtained by conventional methods.

Atropine↗

PubMed1999

Computer simulation of random packing of unequal particles.

A Monte Carlo simulation model for the random packing of unequal spherical particles is presented in this paper. With this model, the particle radii obeying a given distribution are generated and randomly placed within a cubic packing domain with high packing density and many overlaps. Then a relaxation iteration is applied to reduce or eliminate the overlaps, while the packing space is gradually expanded. The simulation is completed once the mean overlap value falls below a preset value. To simulate the random close packing, a "vibration" process is applied after the relaxation iteration. For log-normal distributed particles, the effect of particle size standard deviation, and for bidisperse particles, the effects of particle size ratio and the volume fraction of large particles on packing density and on coordination number are investigated. Simulation results show good agreement with that obtained by experiments and by other simulations. The randomness, homogeneity, and isotropy, which have not been evaluated before for packing of distributed particles, are also examined using statistical measures.

Journal Article↗

PubMed1999

[Atraumatic restorative treatment fillings and fissure sealants in permanent teeth--a 2-year study].

OBJECTIVE: To study the feasibility of providing Atraumatic Restorative Treatment (ART) in schools and in rural areas in China, and to evaluate the acceptance and effectiveness of the treatment. METHODS: The study was conducted among 272 grade one students chosen from four different secondary schools in Deyang of Sichuan Province, China. The mean age of the subjects was 12.5 years. 107 boys and 165 girls were found at the baseline examination to have teeth that were suitable for receiving ART fillings or sealants. The treatments were performed within a month using the glass ionomer Ketac-Molar manufactured by ESPE. Evaluation was carried out at 3 months, one year and two years after treatment. RESULTS: ART fillings were placed in 295 permanent teeth, and the 1-year and 2-year success rates were 95.7% and 91.1% respectively. ART sealants were placed in another 191 permanent teeth, and the 3-month, 1-year and 2-year success rates were 95.2%, 89.1% and 78.8% respectively. The incidence of recurrent caries was very low after two years, which were 2.1% and 0.6% for the fillings and sealants respectively. ART was accepted by the majority of the students. CONCLUSION: ART is a simple, acceptable technique, and is suitable for widespread adoption in China.

Adolescent↗

PubMed1999

[The use of inexact reasoning method for differential diagnosis of pulmonary function].

This article expounds the main idea of the evidence theory and hence presents a mathematical model. Based on the above work, we have developped a computer-aided medical differential diagnosis system with Visual Basic. The system can identify restrictive ventilatory impairment, obstructive ventilatory impairment, mixed ventilatory impairment and normal. according to the valuse of patients' related indexed. In a retrospective test of 290 cases we collected, the rate of agreement between the diagnosis made by this system and the physicians was 93.1%.

Algorithms↗

PubMed1999

[Hybridization experiments using Anopheles minimus from Hainan and Yunnan].

AIM: To observe whether there were any intra-species differences between Anopheles minimus from Hainan(H) and Yunnan(Y). METHODS: Anopheles minimus were collected from cattle shed on the spot. Each isofemale line was set up in the laboratory. Hybridization experiments were conducted by using forced mating between Anopheles minimus from Hainan and Yunnan, for observing the reproductive ability of F1 hybrids. Ovarian nurse cell polytene chromosomes of F1 hybrid females were examined, to observe any synapsis in different zones of chromosomes. RESULTS: No embryo formation was found within the eggs produced by group Y female x H male, the hatching rate was zero. Low hatching rate was shown in other groups with (H female x Y male) F1, except for groups with (H x Y) F1 x Y. Ovarian nurse cell polytene chromosomes from (H x Y) F1 hybrid females showed constant asynapsis at the 29th, 36th and 37th zones in the chromosome 3R, and at the 4th and 6th zones in the chromosome X. CONCLUSION: Reproductive isolation did appear in An. minimus from Hainan and Yunnan.

Animals↗

PubMed1998

Inducible nitric oxide synthase expression is selectively induced in astrocytes isolated from adult human brain.

Inducible nitric oxide synthase (iNOS) expression has been shown to be differentially regulated among different cell types and species. In cultures of primary human fetal glial cells, we have shown that astrocytes rather than microglia express iNOS. In the present study, we extended these findings to primary cultures of astrocytes and microglia derived from adult human brains. Mixed cultures of adult brain tissue were stimulated with IL-1beta and IFNgamma, a combination known to induce iNOS maximally in human fetal cells, and the expression of iNOS was determined by immunocytochemistry. Cell types were determined by morphology as well as immunocytochemistry for GFAP (astrocytes) and CD68 (microglia). The results showed that in cultures of adult human glia, iNOS was expressed following stimulation with cytokines, and the expression was restricted to astrocytes. Astrocyte iNOS immunoreactivity was detected both in the cytosol and in a discrete paranuclear region, a pattern noted in human fetal astrocytes. These results demonstrate that the ability to express iNOS is common to both fetal and adult human astrocytes.

Adult↗

PubMed1998

The quinone-binding site in succinate-ubiquinone reductase from Escherichia coli. Quinone-binding domain and amino acid residues involved in quinone binding.

When purified ubiquinone (Q)-depleted succinate-ubiquinone reductase from Escherichia coli is photoaffinity-labeled with 3-azido-2-methyl-5-methoxy-[3H]6-geranyl-1,4-benzoquinone ([3H]azido-Q) followed by SDS-polyacrylamide gel electrophoresis, radioactivity is found in the SdhC subunit, indicating that this subunit is responsible for ubiquinone binding. An [3H]azido-Q-linked peptide, with a retention time of 61.7 min, is obtained by high performance liquid chromatography of the protease K digest of [3H]azido-Q-labeled SdhC obtained from preparative SDS-polyacrylamide gel electrophoresis on labeled reductase. The partial N-terminal amino acid sequence of this peptide is NH2-TIRFPITAIASILHRVS-, corresponding to residues 17-33. The ubiquinone-binding domain in the proposed structural model of SdhC, constructed based on the hydropathy plot of the deduced amino acid sequence of this protein, is located at the N-terminal end toward the transmembrane helix I. To identify amino acid residues responsible for ubiquinone binding, substitution mutations at the putative ubiquinone-binding region of SdhC were generated and characterized. E. coli NM256 lacking genomic succinate-Q reductase genes was constructed and used to harbor the mutated succinate-Q reductase genes in a low copy number pRKD418 plasmid. Substitution of serine 27 of SdhC with alanine, cysteine, or threonine or substitution of arginine 31 with alanine, lysine, or histidine yields cells unable to grow aerobically in minimum medium with succinate as carbon source. Furthermore, little succinate-ubiquinone reductase activity and [3H]azido-Q uptake are detected in succinate-ubiquinone reductases prepared from these mutant cells grown aerobically in LB medium. These results indicate that the hydroxyl group, the size of the amino acid side chain at position 27, and the guanidino group at position 31 of SdhC are critical for succinate-ubiquinone reductase activity, perhaps by formation of hydrogen bonds with carbonyl groups of the 1,4-benzoquinone ring of the quinone molecule. The hydroxyl group, but not the size of the amino acid side chain, at position 33 of SdhC is also important, because Ser-33 can be substituted with threonine but not with alanine.

Affinity Labels↗

PubMed1998

HIV, but not murine leukemia virus, vectors mediate high efficiency gene transfer into freshly isolated G0/G1 human hematopoietic stem cells.

Recent studies have opened the possibility that quiescent, G0/G1 hematopoietic stem cells (HSC) can be gene transduced; lentiviruses (such as HIV type 1, HIV) encode proteins that permit transport of the viral genome into the nucleus of nondividing cells. We and others have recently demonstrated efficient transduction by using an HIV-1-based vector gene delivery system into various human cell types including human CD34(+) cells or terminally differentiated neurons. Here we compare the transduction efficiency of two vectors, HIV-based and murine leukemia virus (MuLV)-based vectors, on untreated and highly purified human HSC subsets that are virtually all in G0/G1. The HIV vector, but not MuLV vector supernatants, transduced freshly isolated G0/G1 HSC from mobilized peripheral blood. Single-step transduction using replication-defective HIV resulted in HSC that expressed the green fluorescent protein (GFP) transgene while retaining their stem cell phenotype; clonal outgrowths of these GFP+ HSC on bone marrow stromal cells fully retained GFP expression for at least 5 weeks. MuLV-based vectors did not transduce resting HSC, as measured by transgene expression, but did so readily when the HSC were actively cycling after culture in vitro for 3 days in a cytokine cocktail. These results suggest that resting HSC may be transduced by lentiviral-based, but not MuLV, vectors and maintain their primitive phenotype, pluripotentiality, and at least in vitro, transgene expression.

Antigens, CD34↗

PubMed1998

Expression of a p53 mutant in the epidermis of transgenic mice accelerates chemical carcinogenesis.

To develop an in vivo model for studying the role of the p53 tumor suppressor in skin carcinogenesis, a murine p53(172H) mutant (equivalent to human p53(175H)) was expressed in the epidermis of transgenic mice, utilizing a targeting vector based on the human keratin 1 gene (HK1.p53m). HK1.p53m mice developed normally and did not exhibit an obvious epidermal phenotype or develop spontaneous tumors. However, these mice demonstrated an increased susceptibility to a two-stage chemical carcinogenesis protocol, with the rate of formation and number of papillomas being dramatically increased as compared to non-transgenic controls. The majority of papillomas in control mice regressed after termination of 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment, whereas p53m papillomas progressed to carcinomas and metastases. In addition, more advanced malignancy, i.e., undifferentiated spindle cell carcinomas, were exclusively observed in p53m mice. Increased bromodeoxyuridine (BrdU) labeling, accompanied by decreased expression of p21, was observed in HK1.p53m papillomas. In situ examination of centrosomes in HK1.p53m papillomas also revealed marked abnormalities, with 75% of the cells containing > or = 3 centrosomes/cell, whereas centrosome numbers in papillomas from control animals remained normal. These data suggest that the accelerated tumorigenesis observed in chemically-treated p53m mice is most likely due to increased genomic instability resulting from an inhibition of G1 arrest and abnormal amplification of centrosomes.

9,10-Dimethyl-1,2-benzanthracene↗