Search PubMed⌕ Search

Biomedical subjects

H Su

Publications and source records attributed to H Su.

At least 91 records · Page 5Linked to original sources
PubMed1997

[A further study on the correlation between molar response value and molecular connectivity indices].

It has been shown that there exists very good correlation between molar response values and corresponding molecular connectivity indices for alkane, benzene series and alkanol on both TCD and FID and for ketone on TCD. The results of multivariate linear regression are as follows. Molar response values (SM) on TCD: alkanes SM = 32.55 + 32.71 1X + 1.20 2X - 7.33 3X, r = 0.9951, S = 1.6313, N = 32 (1) benzene series SM = 30.00 + 20.30 1Xv + 13.32 2X, r = 0.9880, S = 2.7689, N = 13 (3) alkanols SM =42.22 + 23.71 1Xv + 4.52 2X, r = 0.9914, S = 3.9610, N = 17 (5) ketones SM = 55.10 + 21.46 1Xv + 4.82 2Xv, r = 0.9914, S = 3.1361, N = 11 (7) Molar response values (SM) on FID: alkanes SM = 14.58 + 23.76 1X + 7.77 2X + 2.52 3X, r = 0.9967, S = 2.1762, N = 50 (2) benzene series SM = 39.45 + 22.25 1Xv + 6.63 2X, r = 0.9880, S = 2.4137, N = 20 (4) alkanols SM = -5.31 + 25.48 1Xv + 8.92 2Xv r = 0.9930, S = 4.8979, N = 14 (6) where r and S are regression coefficient and residual standard deviation, respectively; N is the data number; 1X, 2X and 3X are the first, second and third order molecular connectivity indices, respectively. 1Xv and 2Xv are the first and second order molecular connectivity indices for which the oxygen atom and the degree of unsaturation has been revised, respectively.

Alkanes↗
PubMed1997

[Empirical expressions for the chromatographic peak width at inflection points and base].

From EMG function and linear regression, the projective distances on abscissa between inflection points in the left side (TL) or in the right side (TR) and the apex of a chromatographic peak which the asymmetry at 0.1 height fraction is within 1.09-3.00 can be expressed as: TL = -0.7898 + 0.8219 W(0.1,L), TR = 0.03536 + 0.4582 W(0.1,L), where W(0.1,L) is the projective distance on abscissa between the point at 1/10 height fraction in the left side and the apex. The correlation coefficients are all over 0.998 and the relative error limits are within -0.65%-0.40% and -0.39%-0.67%, respectively. The relationship between the peak width at base Wb and the peak width at half height W(0.5) or the peak width at 1/10 height fraction W(0.1) can be expressed as: Wb = 0.04827 + 1.6907 W(0.5), Wb = 1.9066 + 0.5300 W(0.1). The correlation coefficients are all over 0.999 and the relative error limits are within -0.54%-0.69% and -1.05%-1.40%, respectively.

English Abstract↗
PubMed1997

Sensitive in situ hybridization with catalyzed reporter deposition, streptavidin-Nanogold, and silver acetate autometallography: detection of single-copy human papillomavirus.

The usefulness of standard in situ hybridization for viral nucleic acid detection is occasionally limited by its sensitivity limit of 10 to 50 copies per cell. A modified version of the recently described signal amplification method, catalyzed reporter deposition (CARD), and its application to formalin-fixed cells and tissue sections is presented. Deposition of the reporter is facilitated by using horseradish peroxidase catalyzing the deposition of biotinylated tyramide on the location of the probe target. The biotin accumulation created is usually detected with streptavidin-labeled enzymes or fluorochromes. In the present investigation, this step was replaced by streptavidin-Nanogold and combined with silver acetate autometallography. This resulted in deep-black precipitation at positive in situ hybridized reaction sites. The sensitivity of this new approach was tested with a biotinylated, genomic probe specific for human papillomavirus (HPV)-16/18. SiHa cells, a cervical carcinoma-derived cell line with one to two HPV16 copies per cell, and 10 histologically confirmed cervical carcinomas were used for the study. All samples were previously HPV16 positive with solution polymerase chain reaction, but only two of the cervical carcinomas were positive with standard in situ hybridization with barely visible signals. When employing CARD-Nanogold, SiHa cells and 9 of 10 biopsies proved positive with marked signals. It is concluded that this nonisotopic method can detect single viral copies in situ in routinely fixed material and may have the potential to replace in situ polymerase chain reaction in many applications.

Acetates↗
PubMed1997

[An investigation on genotypes of hepatitis C virus in Anhui province].

To study the distribution of HCV genotypes in Anhui province, anti-HCV positive serum samples were collected from 371 hepatitis C patients, 60 patients under haemodialysis and 100 blood donors. HCVRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). Based on the results of PCR positivity, HCV genotyping was investigated by restriction fragment length polymorphism. Results showed that among hepatitis C patients 143 (75.66%) were HCV type II infection, 25 (13.23%) were HCV type III and 12(6.35%) were type II/III co-infection. HCV type I and IV infection appeared in one of each (0.53%). HCV genotype could not be determined in 7 patients because of low HCVRNA titers. These results indicated that HCV II infection was the dominant genotype in Anhui Province. Geographically, HCV type II infection was higher in the southern areas. The patterns of genotype distribution in the southern and northern areas were significant different (P < 0.05). There was no significant difference between HCV genotypes in relation to the history of blood transfusion.

China↗
PubMed1996

Site-directed mutations affecting the spectroscopic characteristics and midpoint potential of the primary donor in photosystem I.

Photosystem I is a member of the iron-sulfur center or type I reaction centers. The primary electron donor in photosystem I is a chlorophyll a dimer termed P700. The biophysical properties of P700 are well understood, but the protein environment that gives it such unique properties is unknown. We have characterized site-directed mutants of the photosystem I reaction center protein PsaB and identified an amino acid, His-656, that interacts closely with one of the P700 chlorophylls. Mutation of His-656 to Asn or Ser increases the oxidation midpoint potential of P700/P700+. by 40 mV. The P700/P700+. optical difference spectra show the appearance of a new bleaching band at 667 nm. Electron nuclear double resonance spectroscopy indicates a significant increase in the hyperfine coupling corresponding to methyl protons at position 12 of the spin carrying chlorophyll a of P700+. The implication of these results to current structural models of the photosystem I reaction center is discussed.

Amino Acid Sequence↗
PubMed1996

A recombinant Chlamydia trachomatis major outer membrane protein binds to heparan sulfate receptors on epithelial cells.

Chlamydial attachment to columnar conjunctival or urogenital epithelial cells is an initial and critical step in the pathogenesis of chlamydial mucosal infections. The chlamydial major outer membrane protein (MOMP) has been implicated as a putative chlamydial cytoadhesin; however, direct evidence supporting this hypothesis has not been reported. The function of MOMP as a cytoadhesin was directly investigated by expressing the protein as a fusion with the Escherichia coli maltose binding protein (MBP-MOMP) and studying its interaction with human epithelial cells. The recombinant MBP-MOMP bound specifically to HeLa cells at 4 degrees C but was not internalized after shifting the temperature to 37 degrees C. The MBP-MOMP competitively inhibited the infectivity of viable chlamydiae for epithelial cells, indicating that the MOMP and intact chlamydiae bind the same host receptor. Heparan sulfate markedly reduced binding of the MBP-MOMP to cells, whereas chondroitin sulfate had no effect on binding. Enzymatic treatment of cells with heparitinase but not chondroitinase inhibited the binding of MBP-MOMP. These same treatments were also shown to reduce the infectivity of chlamydiae for epithelial cells. Mutant cell lines defective in heparan sulfate synthesis but not chondroitin sulfate synthesis showed a marked reduction in the binding of MBP-MOMP and were also less susceptible to infection by chlamydiae. Collectively, these findings provide strong evidence that the MOMP functions as a chlamydial cytoadhesin and that heparan sulfate proteoglycans are the host-cell receptors to which the MOMP binds.

ATP-Binding Cassette Transporters↗
PubMed1996

Selective killing of AFP-positive hepatocellular carcinoma cells by adeno-associated virus transfer of the herpes simplex virus thymidine kinase gene.

The use of viral thymidine kinase (TK) gene coupled with the administration of ganciclovir to render cancer cell death has been studied extensively. Many of these experiments utilized retrovirus to transfer the TK gene under the control of a nonspecific promoter. Because nonspecific expression of the viral TK gene may cause death of proliferating cells, other than cancer cells, we explored the use of a liver-specific promoter and a tumor-specific AFP enhancer to achieve regulated viral TK gene expression for treatment of hepatocellular carcinoma. We also used the adeno-associated virus (AAV) as vector for the delivery of the TK gene because this virus is not associated with any pathological consequences in humans. Because it can infect nondividing S-phase cells, AAV can transfer genes into noncycling tumor cells. A recombinant AAV virus was constructed to include the selectable marker neoR gene and the herpes simplex virus (HSV)-TK gene driven by the human AFP enhancer and the albumin promoter. The liver-predominant expression pattern of the TK gene was observed when this construct was tested in transgenic mice. When human hepatocellular carcinoma cell lines displaying different levels of AFP and albumin and nonhepatocyte tumor cell lines were infected with the recombinant AAV virus, ganciclovir treatment caused only AFP and albumin-positive hepatocellular carcinoma cells death, but not nonhepatocyte tumor cells or AFP and albumin-negative hepatic tumor cells. Moreover, the dose required to kill the cancer cells was inversely proportional to the level of AFP expression in the cells.

Albumins↗
PubMed1996

Electron Microscopical Autometallography: Immunogold-Silver Staining (IGSS) and Heavy-Metal Histochemistry

Immunogold-silver staining (IGSS) utilizes a histochemical method called autometallography (AMG) to amplify tiny gold particles to sizes easily visible both in light and electron microscopy. In both applications it is advisable to use the smallest possible gold diameters (1-6 nm) to obtain the highest sensitivity, thus, allowing minute amounts of the target substance to be demonstrated. Gold labels smaller than 10 nm in diameter have been clearly shown to give the highest labeling densities of antigen-antibody binding sites. AMG can be used for the detection of catalytic crystal lattices of metallic gold and silver, and sulfides or selenides of mercury, silver, copper, bismuth, and zinc. The method has its roots in "physical development" technique, transplanted from photography to histology by Liesegang at the beginning of this century. In 1981, a series of papers were published by one of us with the purpose of introducing a reliable and easy-to-handle technique for light microscopical and ultrastructural studies. AMG has a multitude of applications apart from its use in detecting tissue metals. These include the highly sensitive and efficient in situ colloidal gold tracing of peptides, proteins, and amines by immunocytochemistry using the IGSS method, of carbohydrates by lectin IGSS, and of nucleic acids by IGSS in situ hybridization, IGSS in situ polymerase chain reaction, and IGSS in situ self-sustained sequence replication-based amplification (in situ 3SR) techniques, the last two even performing with single-copy sensitivity. Applications of pre- and postembedding AMG for semithin and ultrathin tissue sections are described.

Journal Article↗
PubMed1996

Improved wool production in transgenic sheep expressing insulin-like growth factor 1.

Transgenic sheep were produced by pronuclear microinjection with a mouse ultra-high-sulfur keratin promoter linked to an ovine insulin-like growth factor 1 (IGF1) cDNA. Five transgenic lambs resulted from the microinjection of 591 embryos; one male and one female showed IGF1 expression in the skin. A progeny test of the ram was carried out by matings to 43 non-transgenic ewes. Of 85 lambs born, 43 (50.6%) were transgenic. At yearling shearing (approximately 14 months of age), clean fleece weight was on average 6.2% greater in transgenic animals than in their non-transgenic half-sibs, with a greater effect in males (9.2%) than females (3.4%). Transgenics showed a small but significant increase in bulk, but male transgenics had a lower staple strength than female transgenics and non-transgenics which did not differ significantly. There were no significant differences in fiber diameter, medullation, and hogget body weight. To our knowledge this is the first reported improvement in a production trait by genetic engineering of a farm animal without adverse effects on health or reproduction.

Animals↗
PubMed1996

Association between a transmembrane protein tyrosine phosphatase and the cadherin-catenin complex.

Cadherins are calcium-dependent cell adhesion molecules that play fundamental roles in embryonic development, tissue morphogenesis, and cancer. A prerequisite for their function is association with the actin cytoskeleton via the catenins. Tyrosine phosphorylation of beta-catenin, which correlates with a reduction in cadherin-dependent cell adhesion, may provide cells with a mechanism to regulate cadherin activity. Here we report that beta-catenin immune precipitates from PC12 cells contain tyrosine phosphatase activity which dephosphorylates beta-catenin in vitro. In addition, we show that a member of the leukocyte antigen-related protein (LAR)-related transmembrane tyrosine phosphatase family (LAR-PTP) associates with the cadherin-catenin complex. This association required the amino-terminal domain of beta-catenin but does not require the armadillo repeats, which mediate association with cadherins. The interaction also is detected in PC9 cells, which lack alpha-catenin. Thus, the association is not mediated by alpha-catenin or by cadherins. Interestingly, LAR-PTPs are phosphorylated on tyrosine in a TrkA-dependent manner, and their association with the cadherin-catenin complex is reduced in cells treated with NGF. We propose that changes in tyrosine phosphorylation of beta-catenin mediated by TrkA and LAR-PTPs control cadherin adhesive function during processes such as neurite outgrowth.

Amino Acid Sequence↗
PubMed1996

Isolation and expression in Escherichia coli of hepB and hepC, genes coding for the glycosaminoglycan-degrading enzymes heparinase II and heparinase III, respectively, from Flavobacterium heparinum.

Upon induction with heparin, Flavobacterium heparinum synthesizes and secretes into its periplasmic space heparinase I (EC 4.2.2.7), heparinase II, and heparinase III (heparitinase; EC 4.2.2.8). Heparinase I degrades heparin, and heparinase II degrades both heparin and heparan sulfate, while heparinase III degrades heparan sulfate predominantly. We isolated the genes encoding heparinases II and III (designated hepB and hepC, respectively). These genes are not contiguous with each other or with the heparinase I gene (designated hepA). hepB and hepC were found to contain open reading frames of 2,316 and 1,980 bp, respectively. Enzymatic removal of pyroglutamate groups permitted sequence analysis of the amino termini of both mature proteins. It was determined that the mature forms of heparinases II and III contain 746 and 635 amino acids, respectively, and have calculated molecular weights of 84,545 and 73,135, respectively. The preproteins have signal sequences consisting of 26 and 25 amino acids. Truncated hepB and hepC genes were used to produce active, mature heparinases II and III in the cytoplasm of Escherichia coli. When these enzymes were expressed at 37 degrees C, most of each recombinant enzyme was insoluble, and most of the heparinase III protein was degraded. When the two enzymes were expressed at 25 degrees C, they were both present predominantly in a soluble, active form.

Amino Acid Sequence↗
PubMed1996

Effects of sex-linked imperfect albinism (sal-s) in the chicken on the relationships of plasma concentrations of progesterone and 17 beta-estradiol with egg production.

Effects of the sal-s gene for sex-linked imperfect albinism on the relationships of plasma concentrations of progesterone (P4) and estradiol (E2) with egg production were investigated during the laying period. Egg production of 17 albino and 16 nonalbino hens was recorded from 19 to 60 wk of age. Blood samples of these hens were taken between 1330 and 1500 h at 19 and 20 wk of age and every 4 wk until 60 wk of age. At 61 wk, blood samples were taken 6, 5, and 4 h before a midsequence ovulation. Plasma P4 and E2 were measured by RIA. There was no difference between genotypes in days to first egg (157.8 vs 158.1 d). Hen-day egg production of albinos was greater (P < 0.05) than that of nonalbinos in the 4-wk periods between 52 and 56 wk (83.8 vs 69.2%) and 56 and 60 wk (81.3 vs 64.3%). Egg production for the entire laying cycle was not different between genotypes (81.0 vs 73.0%, P = 0.08). Plasma P4 and E2 concentrations were not different between albino and nonalbino hens. From 28 to 60 wk of age, partial correlation coefficients between P4 and egg production, and E2 and egg weight were significant for albino hens (r = 0.15 and 0.16, respectively) but not for nonalbinos (r = -0.03 and -0.1, respectively), and age and P4 concentrations were negatively correlated for both albinos (r = -0.22, P < 0.01) and nonalbinos (r = -0.32, P < 0.01). Preovulatory levels of P4 in albino hens were higher (P < 0.05) than those in nonalbinos. Plasma E2 was higher in albinos than in nonalbinos 5 h before ovulation (P < 0.05). These data suggest that increased egg production of albino hens is associated with differences in P4 and E2 metabolism.

Age Factors↗
PubMed1996

Experimental study of right ventricular assist in acute right ventricular failing.

The efficacy of right atrial-pulmonary artery (RA-PA) bypass during acute right ventricular failure (RVF) produced by pulmonary artery constriction in dogs was examined in this study Control group (n = 7) was supported with conventional volume loading and inotropic therapy. In the experimental animals (n = 8), RA-PA bypass was initiated 5 min, after the onset of severe RVF. Three control animals died from refractory ventricular fibrillation within one hour of RVF. No animals in the experimental group died within two hours of RA-PA bypass, but the histological study of the lungs in these animals demonstrated peribronchial, perivascular and intraalveolar hemorrhage. Light microscopic and electron microscopic examination of the myocardial specimens of the right ventricular free wall displayed the myocardial structures and ultrastructures were maintained effectively with RA-PA bypass while irreversible myocardial injuries occurred in the control animals after two hours of RVF with conventional therapy. During the 2 hours of RA-PA bypass, the hemodynamic indices were also maintained better when compared to the control animals. It may be concluded, a roller pump right ventricular assist device effectively unloads the acute failing right ventricle, maintains systemic cardiac output, and significantly reverses the myocardial ischemia during right ventricular failure, but RA-PA bypass may induce pulmonary hypertension due to increased pulmonary vascular resistance secondary to pulmonary edema and interstitial hemorrhage.

Animals↗
PubMed1996

[Mifepristone for induction of labor].

OBJECTIVES: To evaluate the effectiveness of mifepristone administered prior to labor induction, and to study its safety for mother and fetus. METHODS: 124 nullipara, 37-42 gestational weeks, with indications for labor induction were recruited, and randomly allocated into 2 groups. Group A (n = 62) was given mifepristone 50 mg q.12.h. for 2 days, followed by PG05 or oxytocin, while group B (n = 62) was were observed for 2 days before labor induction by PG05 or oxytocin. Blood samples were obtained for determination of mifepristone concentration and hormone levels including estradiol, progesterone, testosterone, cortisol, aldosterone and human placental prolactin at recruitment and immediately after delivery, and umbilical cord blood was collected at the same time. RESULTS: Cervical Bishop score increased significantly in the mifepristone pretreatment group when compared with the control group. 22.58% of the women underwent spontaneous delivery after mifepristone treatment and 4.84% of the controls followed suit (P < 0.01). The oxytocin dose required was significantly less in group A, but the success rate was higher (P < 0.05). Side-effects associated with mifepristone was mild. Maternal serum mifepristone peak levels ranged from 200 to 700 micrograms/L, with t1/2 of 21.7 hr. The concentration of mifepristone in umbilical blood was low and stable. The ratio of umbilical/maternal mifepristone level was 0.25 +/- 0.08. Determination of hormone profiles did not show any significant difference between the 2 groups. CONCLUSIONS: Mifepristone is an effective inductive agent for cervical ripening and initiation of labor in term pregnancy, and can improve the outcome of labor induction.

Abortifacient Agents, Nonsteroidal↗
PubMed1995

Glutamate-101 is critical for the function of the sodium and chloride-coupled GABA transporter GAT-1.

We have investigated the possible role of selected negatively-charged amino acids of the sodium and chloride-coupled GABA transporter GAT-1 on sodium binding. These residues located adjacent to putative transmembrane domains and which are conserved throughout the large superfamily of neurotransmitter transporters were changed by site-directed mutagenesis. The functional consequences were that one of the residues, glutamate-101, was critical for transport. Its replacement by aspartate left only 1% of the activity, and no activity could be detected when it was replaced by other residues. Expression levels and targeting to the plasma membrane of the mutant transporters appeared normal. Transient sodium currents were not observed in the mutants, and increased sodium concentrations did not affect the percentage of wild type transport of the E101D mutant. It is concluded that residue glutamate-101 is critical for one or more of the conformational changes of GAT-1 during its transport cycle.

Amino Acid Sequence↗
PubMed1995

Functional role of arginine-11 in the N-terminal helix of skeletal troponin C: combined mutagenesis and molecular dynamics investigation.

The two main structural differences between calmodulin (CaM) and skeletal troponin C (sTnC) are the absence in CaM of (i) the short N-terminal helix in TnC and (ii) the triplet KGK (residues 91-93; numbering according to chicken sTnC). It was recently shown that deletion of both structural groups from sTnC imparted to the resulting construct the CaM-like ability to activate phosphodiesterase (PDE) and to regulate force development in smooth muscle. To continue probing of the structural basis of the differential behavior of sTnC and CaM, residue Arg-11 in rabbit sTnC was mutated to Ala because the interactions of Arg-11 with distal residues in the N-terminal domain seem to link the N-terminal helix to the rest of the structure. The mutant exhibits CaM-like function in its ability to activate PDE (about 50% of CaM at 5 microM concentration). If, in addition, the KGK triplet is also deleted, PDE activation increases to about 80%. Both constructs retain their TnC function to nearly 100%. To explore the mechanistic basis of this remarkable observation, computational simulations of the molecular dynamics (MD) were carried out for both wild-type 4Ca2+.sTnC and the 4Ca2+.R11A mutant, and the results were compared to those from earlier simulations of 4Ca2+.CaM. Two types of structural changes observed from such simulations of the molecular dynamics of CaM had been considered to have a functional role: (i) a compaction to a more globular form and (ii) a reorientation of the Ca-binding domains around the central tether helix.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Platinum anticancer drug binding to DNA detected by thickness-shear-mode acoustic wave sensor.

Nucleic acid has been attached to the electrodes of thickness-shear-mode acoustic wave devices to produce a biosensor for platinum-based drugs. The decreases in series resonant frequency for interactions of DNA with both cis- and transplatin are indicative of two distinct kinetic processes. The results of a kinetic analysis are interpreted in terms of nucleic acid binding of the hydrolysis products of the two drugs. Concentration-dependent decreases of series resonant frequency show that the limit of detection for the drugs is approximately 10(-7) M. Motional resistance changes for nucleic acid-drug interactions also convey information regarding the chemistry of the macromolecules at the interface.

Animals↗