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Biomedical subjects

H Feng

Publications and source records attributed to H Feng.

At least 55 records · Page 3Linked to original sources
PubMed2000

Changes of microsomal membrane properties in spring wheat leaves (Triticum aestivum L.) exposed to enhanced ultraviolet-B radiation.

The properties of microsomal membranes in spring wheat leaves (Triticum aestivum L. cv. Ganlong No. 92-005) exposed to (0) control, 8.64 (T1) and 11.2 kJ m(-2) day(-1) (T2) biologically effective UV-B irradiation (UV-B(BE)) were studied under greenhouse conditions. These irradiance levels correspond to a decrease in the stratospheric ozone of approximately 12.5 and 20%, respectively, for a clear solstice day at Lanzhou (36.04 degrees N, 1550 m), China. Compared with controls, the content of malondialdehyde (MDA) increased by 70.8% in T1 and 83.8% in T2 on the 7th day of the radiation, and the IUFA (index of unsaturated fatty acids) decreased, indicating peroxidation of lipid acids. Simultaneously, a drastic decrease of phospholipid content after 21 days and an increase of membrane lipid microviscosity on UV-B irradiation were also found, suggesting a reduction in the fluidity of membrane lipids. Ethylene emission by the microsomal membrane, in the presence of exogenous 1-aminocyclopropane-1-carboxylic acid was higher in the wheat seedlings after 7, 14 and 21 days' irradiation than in the controls. These changes were correlated with a rise in lipoxygenase activity. Membrane-bound enzymes (Ca2+ -ATPase and Mg2+ -ATPase) were promoted by UV radiation in the first 7 days and significantly decreased after 14 and 21 days' treatment in comparison to control. Our results suggest that UV-B radiation may cause changes in structural complexity and function of microsomal membranes in spring wheat leaves.

Dose-Response Relationship, Radiation↗
PubMed2000

[A molecular cytogenetic study on chromosome anomalies of chronic myeloid leukemia].

OBJECTIVE: To study the bcr/abl fusion gene in chronic myeloid leukemia (CML) cases with Philadelphia chromosome(Ph) negative, and variant Ph translocations and other chromosome anomalies. METHODS: The status of bcr/abl fusion gene in 8 kinds of chromosome anomalies was tested with dual-color fluorescence in situ hybridization (D-FISH) technique. RESULTS: The positive hybridization was demonstrated in 3 cases of variant Ph CML and other 7 cases of standard Ph, respectively. In 2 cases of Ph-negative CML, one case that had karyotype such as 46,XY,t(9;18) showed positive hybridization, the other case with 46,XY,inv(2) showed negative result. CONCLUSION: The result demonstrates that D-FISH technique is reliable for detecting bcr/abl fusion gene. The existence of negative bcr/abl fusion gene CML implies that some other initial events inducing CML might have occurred in such cases.

Adult↗
PubMed2000

[Study on pathogenicity of sputum from cavity of sputum negative patients with pulmonary tuberculosis after short course chemotherapy].

OBJECTIVE: To find out whether or not the sputa of pulmonary tuberculosis(PTB) patients with cavitation but sputum negative have pathogenicity after short course chemotherapy. METHODS: Guinea pigs were inoculated with sputa of PTB patients who were with cavitation but sputum negative after having finished short course chemotherapy. Then their body weight, enlargement of local lymph nodes and other ordinary symptom were observed. Six weeks later, pathological changes of TB in the internal organs were examined by dissecting these guinea pigs. Culture and drug resistance test of tubercle bacillus were also conducted. All of which were with negative and positive controls. RESULTS: Of the 63 cases included, 3(5%) patients' sputa resulted in tuberculous nodulation varying in amount in lung, liver and spleen of these guinea pigs, and the culture for tubercle bacillus of these sputa was positive too. CONCLUSIONS: 5% of sputum collected from PTB patients with cavitation but sputum negative still show pathogenicity after short course chemotherapy. For the cases with drug-resistant PTB and slow sputum negative conversion, the treatment should be prolonged and tubercle bacilli in their sputa should be monitored.

Animals↗
PubMed2000

[Presence and replication of TTV DNA in peripheral blood mononuclear cells from hepatitis patients with TTV infection].

OBJECTIVE: To study the presence and replication of TTV DNA in the peripheral blood mononuclear cells (PBMC) from hepatitis patients with TTV infection. METHODS: Nested-PCR (nPCR) was performed for detecting the TTV DNA from the sera, PBMCs and feces of 16 patients with non-A to non-G hepatitis in Beijing Ditan Hospital from Oct. 1997 to Oct. 1998. PBMC DNAs were aslo digested by mung bean nuclease and amplified by nPCR to clasify if TTV DNA was still positive. nPCR products of the sera, PBMCs and feces of 5 hepatitis patients with non-A to non-G hepatitis were cloned and sequenced. RESULTS: 14 of the 16 samples of PBMC and 5 of the 16 samples of the feces were TTV DNA positive. Two of the 14 samples of the PBMC were still positive after the digestion and amplification of the single-stand DNA. Sequence analysis showed that there was more than 95% nucleotide homology among the sequenced 5 clones (from the sera, PBMC and feces of the 5 patients) and reported AB008394 (from Japan) and AF079173 (from China). Virus loading of patients whose feces were positive by nPCR was obviously more than the patients with negative TTV DNA. CONCLUSION: TTV DNA can exist and replicate in the PBMC; the hepatocytes of patients with TTV infection are not the only place of TTV existence and replication.

Adult↗
PubMed2000

[The influence of different root length on stress distribution in the bone around abutment root of telescopic overdenture].

OBJECTIVE: To investigate the influence of bone height around the roots on stress distribution in a mandible with two canines remained and covered with an telescopic overdenture. METHODS: Three-dimensional finite element method. RESULTS: As the height of the bone around the roots decreased, the stress increased. But the maximum stress in the bone in this study is lower than that in the bone around the canine under normal condition. CONCLUSION: In the mandible, when the alveolar bone resorption reaches the apical 1/3 of canine (root length 4, 5 mm), if part of the tooth crown was removed, to make an acceptable crown/root ratio, so the canine can be used as the abutment of an overdenture.

Compressive Strength↗
PubMed2000

[Clinical appliance of magnetic attachments in mandibular complete overdentures].

OBJECTIVE: To observe the clinical effect of magnetic attachment with overdenture. METHODS: Ten subjects were selected and treated with Magnetic EX-600 retained mandibular complete overdentures. Each patient's masticatory function, overdenture retention force and abutment condition were measured at different periods and the statistics of each individual were compared respectively. RESULTS: Magnetic attachments can provide good retention for mandibular complete overdentures and improve the masticatory performance of the patients. What's more, the mobility and periodontal index of abutments were improved after 6 months. CONCLUSION: Magnetic EX-600 is very useful to improve the function of mandibular overdentures.

Aged↗
PubMed2000

[The investigation of color selection of 4340 cases of ceramic restorations].

OBJECTIVE: To find color coordinates of Vita color tabs compare with Chinese natural teeth and summarize the skills of color matching. METHODS: We studied 15,836 ceramic restorations of 4340 cases from 138 clinics in 18 provinces throughout China and compared their shade with that of the adjacent natural teeth using the Vita shade guide which has 16 standard tooth colors. Statistical analyses was made by comparing aptness of Chinese teeth with Vita shade. RESULTS: We found that 64.47% of the restorations were matched by Vita A, 15.85% were matched by Vita B, and 19.68% were matched by Vita C and D. The arrangement of Vita 16 colors by using frequency was A2, A3, B2, A1, A3.5, C1, D2, D3, C2, B3, C3, B1, A4, D4, B4 and C4. The first five color matching tabs used most frequently covered 73.85% of the total, while the last four colors only covered 3.07%. It seemed that Vita color tabs could not match well with Chinese teeth. We found that the shade of natural teeth was closely related to sex. But there were no significant difference between tooth color and different areas. CONCLUSION: Tooth color is closely related to sex. The color of ceramic crowns in men are darker than that in women. We have evidences that there are clear differences in color distribution between Chinese natural teeth and Vita shade guide.

China↗
PubMed2000

[Effects of urapidil and cimetidine on wedged hepatic venous pressure and systemic hemodynamics in cirrhotic patients with portal hypertension].

OBJECTIVE: To compare the effects of urapidil and cimetidine on portal pressure and systemic hemodynamics. METHODS: We observed the effects of urapidil (urapidil HCl, n = 15), cimetidine (n = 20) and placebo (0.9% sodium chloride, n = 10) on wedged hepatic venous pressure (WHVP), hepatic venous pressure gradient (HVPG), and systemic hemodynamics. RESULTS: Urapidil at a dosage of 25 mg intravenously reduced WHVP from 33.33 +/- 7.85 cm H2O to 23.75 +/- 6.83 cm H2O, the average value was 28.75% +/- 9.81% (P > 0.01); and HVPG from 21.92 +/- 2.34 cm H2O to 14.07 +/- 3.57 cm H2O, the average value was 35.81% +/- 8.71% (P < 0.01). The free hepatic venous pressure (FHVP) however was not changed significantly (P > 0.05). The heart rate was increased from 70 +/- 13 BPM to 79 +/- 21 BPM (P < 0.05), and the systolic blood pressure and the diastolic blood pressure were reduced from 122 +/- 40 mm Hg to 95 +/- 32 mm Hg and 75 +/- 17 mm Hg to 55 +/- 15 mm Hg respectively (P < 0.01). After cimetidine administered at a dosage of 400 mg intravenously, WHVP and HVPG were reduced from 34.25 +/- 7.34 cm H2O to 29.05 +/- 7.03 cm H2O and 23.14 +- 8.15 cm H2O to 17.13 +/- 4.28 cm H2O; and the average value was 15.18% +/- 8.64% and 26.00% +/- 12.19% respectively (P < 0.01). But heart rate, blood pressure and FHVP were not altered after use of cimetidine ( P > 0.05). In the control group (n = 10), WHVP, HVPG, FHVP, heart rate, as well as blood pressure were not changed after placebo treatment. CONCLUSIONS: Both urapidil and cimetidine could reduce WHVP and HVPG significantly in cirrhotic patients with portal hypertension, and the effect of the two agents on WHVP and HVPG was not obviously different (P > 0.05). However, the systemic hemodynamic effects induced by urapidil were more significant compared with cimetidine.

Adult↗
PubMed1999

234Th and 7Be as tracers for transport and sources of particle-associated contaminants in the Hudson River Estuary.

The natural radionuclides 234Th and 7Be have known sources in estuaries and strongly and rapidly associate with particles. They are thus good tracers of the transport and sources of particles in the suspended sediment reservoir, and, by implication, of particle-associated contaminants such as heavy metals. In the Hudson River estuary, 234Th is produced from decay of dissolved 238U, which varies linearly with salinity, while 7Be is added directly to the estuary from the atmosphere. The 234Th/7Be activity ratio eliminates variations in radionuclide specific activities that result from changes in sediment grain size or composition. Sampling in the Hudson under conditions of low and high river flow shows that 234Th/7Be in suspended sediment increases from low salinity to higher salinity waters at all sampling times. The Th/Be activity ratio may thus be used as a tracer of where particles are labeled with these radionuclides in the estuary and of the relative importance of resuspension and particle transport through the estuary. The distribution of heavy metals in the suspended sediment reservoir can be compared with that of 234Th/7Be by normalizing the metals to Fe. Iron and Al are well correlated in suspended sediments of the Hudson, indicating that either element can be used to normalize grain size effects on specific concentrations of metals. Ratios of Ag and Pb to Fe in suspended particles generally increase down-estuary at all sampling times, whereas Cu, Zn and Cd-to-Fe ratios show more scatter and less consistency in trends. Both source(s) and chemical behavior affect the metal/Fe ratios. The strongest positive correlation with 234Th/7Be is seen for Ag/Fe, reflecting the dominance of lower estuary sources of this trace metal to the Hudson. Relationships between Pb/Fe, Cu/Fe and 234Th/7Be are less strong, reflecting multiple sources of these elements. No correlation is seen for Cd/Fe with 234Th/7Be, indicating either a source up-river or release of Cd as its Kd decreases with increasing salinity.

Beryllium↗
PubMed1999

Characterization of the targeting, binding, and phosphorylation site domains of an A kinase anchor protein and a myristoylated alanine-rich C kinase substrate-like analog that are encoded by a single gene.

A novel Drosophila A kinase anchor protein, Drosophila A kinase anchor protein 200 (DAKAP200), is predicted to be involved in routing, mediating, and integrating signals carried by cAMP, Ca(2+), and diacylglycerol (Li, Z., Rossi, E. A., Hoheisel, J. D., Kalderon, D., and Rubin, C. S. (1999) J. Biol. Chem. 274, 27191-27200). Experiments designed to assess this hypothesis now (a) establish the function, boundaries and identity of critical amino acids of the protein kinase AII (PKAII) tethering site of DAKAP200; (b) demonstrate that residues 119-148 mediate binding with Ca(2+)-calmodulin and F-actin; (c) show that a polybasic region of DAKAP200 is a substrate for protein kinase C; (d) reveal that phosphorylation of the polybasic domain regulates affinity for F-actin and Ca(2+)-calmodulin; and (e) indicate that DAKAP200 is myristoylated and that this modification promotes targeting of DAKAP200 to plasma membrane. DeltaDAKAP200, a second product of the DAKAP200 gene, cannot tether PKAII. However, DeltaDAKAP200 is myristoylated and contains a phosphorylation site domain that binds Ca(2+)-calmodulin and F-actin. An atypical amino acid composition, a high level of negative charge, exceptional thermostability, unusual hydrodynamic properties, properties of the phosphorylation site domain, and a calculated M(r) of 38,000 suggest that DeltaDAKAP200 is a new member of the myristoylated alanine-rich C kinase substrate protein family. DAKAP200 is a potentially mobile, chimeric A kinase anchor protein-myristoylated alanine-rich C kinase substrate protein that may facilitate localized reception and targeted transmission of signals carried by cAMP, Ca(2+), and diacylglycerol.

A Kinase Anchor Proteins↗
PubMed1999

[Effect of low dose gamma-irradiation and cigarette smoking on growth and reflex behavior in mice].

Pregnant mice were exposed to different level of gamma-irradiation(60Co 0, 0.25, 0.5 and 1.0 Gy) and water solutions containing different contents of substance from cigarette smoke(0, 0.5, 1.0, 1.5 and 2.0 cigarette/mouse). Results showed that the effect of low dose gamma-irradiation and high concentration cigarette smoke substance could delay the appearance of four physiological markers (eye opening, pinna detachment, hair growth and tooth growth) and the acquisition of four reflexes(surface righting, air righting, virual placing and auditory orienting). A significant combined effect was also observed.

Animals↗
PubMed1999

Break up to act up.

Explore the source record for details and available documents.

DNA-Binding Proteins↗
PubMed1999

CUL-2 is required for the G1-to-S-phase transition and mitotic chromosome condensation in Caenorhabditis elegans.

The human cullin protein CUL-2 functions in a ubiquitin-ligase complex with the von Hippel-Lindau (VHL) tumour suppressor protein. Here we show that, in Caenorhabditis elegans, cul-2 is expressed in proliferating cells and is required at two distinct points in the cell cycle, the G1-to-S-phase transition and mitosis. cul-2 mutant germ cells undergo a G1-phase arrest that correlates with accumulation of CKI-1, a member of the CIP/KIP family of cyclin-dependent-kinase inhibitors. In cul-2 mutant embryos, mitotic chromosomes are unable to condense, leading to unequal DNA segregation, chromosome bridging and the formation of multiple nuclei.

Amino Acid Sequence↗
PubMed1999

Identification of two major histocompatibility complex class Ib genes, Q7 and Q9, as the Ped gene in the mouse.

The Ped (preimplantation embryonic development) gene influences the rate of preimplantation embryonic development and subsequent embryonic survival. The protein product of the Ped gene, the Qa-2 protein, is a major histocompatibility complex (MHC) class Ib protein. There are two alleles of the Ped gene, fast (Qa-2 [+]) and slow (Qa-2 [-]). Qa-2 is encoded by four very similar MHC class Ib genes: Q6, Q7, Q8, and Q9. Recent research in our laboratory has shown that the Ped phenotype is potentially encoded by the Q7 and/or Q9 gene because the Q7 and Q9 genes, but not the Q6 or Q8 gene, are expressed during preimplantation mouse embryonic development. In this study we utilized microinjection of transgenes to assess the functional roles of both the Q7 and Q9 genes in control of the rate of preimplantation development. The Q7 gene, the Q9 gene, and a combination of the Q7 and Q9 genes were microinjected into Ped slow zygotes, and the Ped phenotype and cell surface expression of Qa-2 protein were assayed after a 72-h or 96-h incubation period. We found that the microinjected individual Q7 and Q9 genes increased the rate of preimplantation development. Simultaneous injection of the Q7 and Q9 genes did not have a synergistic effect on the Ped phenotype. Microinjection of the Q7 and/or Q9 genes resulted in protein expression in 10-25% of the microinjected embryos. These results show that both the Q7 and Q9 genes encode the mouse Ped phenotype.

Alleles↗
PubMed1999

Muscle cell peeling from micropatterned collagen: direct probing of focal and molecular properties of matrix adhesion.

To quantitatively elucidate attributes of myocyte-matrix adhesion, muscle cells were controllably peeled from narrow strips of collagen-coated glass. Initial growth of primary quail myoblasts on collagen strips was followed by cell alignment, elongation and end-on fusion between neighbors. This geometric influence on differentiation minimized lateral cell contact and cell branching, enabling detailed study of myocyte-matrix adhesion. A micropipette was used to pull back one end of a quasi-cylindrical cell while observing in detail the non-equilibrium detachment process. Peeling velocities fluctuated as focal roughness, microm in scale, was encountered along the detachment front. Nonetheless, mean peeling velocity ( microm/second) generally increased with detachment force (nN), consistent with forced disruption of adhesion bonds. Immunofluorescence of beta1-integrins correlated with the focal roughness and appeared to be clustered in axially extended focal contacts. In addition, the peeling forces and rates were found to be moderately well described by a dynamical peeling model for receptor-based adhesion (Dembo, M., Torney, D. C., Saxman, K. and Hammer, D. (1988). Proc. R. Soc. Lond. B 234, 55-83). Estimates were thereby obtained for the spontaneous, molecular off-rate (kooff, (less than or equal to)10/seconds) and the receptor complex stiffness (kappa, approx. 10(-5)-10(-6) N/m) of adherent myocytes. Interestingly, the local stiffness is within the range of flexible proteins of the spectrin superfamily. The overall approach lends itself to elucidating the developing function of other structural and adhesive components of cells, particularly skeletal muscle cells with specialized components, such as the spectrin-homolog dystrophin and its membrane-linked receptor dystroglycan.

Animals↗
PubMed1999

[A study on polymorphism of mitochondrial DNA D loop in the Han nationality in China].

OBJECTIVE: To investigate the polymorphism of mitochondrial DNA D loop in the Han nationality in China and the mean nucleic acid substitute frequency on each site. METHODS: A 465bp-long DNA fragment in mtDNA D loop was amplified by PCR technique and the polymorphism was analyzed by restriction fragment length polymorphism (RFLP) using 6 restriction enzymes (on 10 sites). Some samples were analyzed by direct sequencing of PCR products. RESULTS: RFLP analyses with 6 restriction enzymes on the 10 sites generated 14 restriction types. The calculated mean nucleic acid substitute frequency (based on Nei formula) on each site of mtDNA D loop in the Han nationality in China was 0.029. CONCLUSION: The mean nucleic acid substitute frequency on each site in the D loop region was 10 times as high as that in mtDNA.

Asian People↗
PubMed1999

Development of an immunocontraceptive vaccine. Current status.

Development of an effective and modern contraceptive vaccine is a key factor in the global issue of regional population growth as well as agricultural, medical, economic and social development. A review was done of the current medical literature concerning development of an immunocontraceptive vaccine and relative molecular biology technology. Various approaches have been taken to identify candidate-specific antigens for immunocontraceptive development, such as sperm, zona pellucida and hormonal antigens. Suppressed fertility and the reversibility of these effects on mammalian species, including humans, have been demonstrated. The successful results obtained so far support the continued investigation for an effective immunocontraceptive vaccine.

Animals↗