Biomedical subjects

D Liang

Publications and source records attributed to D Liang.

At least 73 records · Page 4Linked to original sources

PubMed1999

[Expanded polytetrafluoroethylene with different pore diameter for keratoprosthesis cell ingrowth and corneal metabolism].

PURPOSE: (1). To study the relationship between the different pore diameter of the expanded polytetrafluoroethylene, (ePTFE) and the rate of cellular ingrowth in cornea; (2). To evaluate the influence of implant on corneal metabolism. METHODS: Two kinds of ePTFE disk with 45 microns and 28 microns pore diameter were implanted after a free-hand intralamellar dissection. The eyes were examined by slit-lamp biomicroscopy up to 7 months postoperatively. The corneas were removed and examined by light and transmission electron microscopy. RESULTS: Stromal fibroblasts penetrate, proliferate, and synthesize collagen in the pore of these two kinds of ePTFE, while the rate of cellular ingrowth and collagen deposition was greater in the ePTFE with 45 microns pore than 28 microns pore. Lipid deposits occurred in 3 eyes with 45 microns pore and in 5 eyes with 28 microns pore (P > 0.05). Dicks remained in corneas for 7 months without any extrusion in all eyes. CONCLUSION: Stromal fibroblasts can penetrate, proliferate, and synthesize collagen in the pore of both two kind of ePTFE, while cells penetrate greatly in the larger pore. Dicks interfere corneal metabolism in some degree. The ePTFE with 45 microns pore diameter, 200 mm thick, 84% porosity is a suitable material for the skirt of the keratoprosthesis.

Animals↗

PubMed1998

Prolonged seizure suppression by a single implantable polymeric-TRH microdisk preparation.

Thyrotropin-releasing hormone (TRH; Protirelin) is an endogenous neuropeptide known to have anticonvulsant effects in several seizure models and in intractable epileptic patients. Like most neuropeptides, its duration of action may be limited by a lack of sustained site-specific bioavailability. To attempt to provide long-term delivery, we attached TRH to a biodegradable polyanhydride copolymer as a sustained-release carrier. Utilizing the rat kindling model of temporal lobe epilepsy, a single TRH microdisk implanted stereotaxically into the seizure focus (amygdala) significantly suppressed kindling expression when assessed by the number of stimulations required to reach each behavioral stage and to become fully kindled (8.63 +/- 0.92 vs. 16.17 +/- 1.37; Mean +/- S.E.M.). Two indices of seizure severity, afterdischarge duration (Mean +/- S.E.M., sec.) (stimulated amygdala [87.40 +/- 5.47 vs. 51.80 +/- 15.65] and unstimulated amygdala [89.60 +/- 5.55 vs. 48.67 +/- 15.8] and clonus duration (71.2 +/- 5.94 vs. 29.40 +/- 8.87; Mean +/- S.E.M., sec.), were also significantly reduced by a single polymeric-TRH implant. Fifty days after initiation of the study a significant reduction in clonus duration (53.90 +/- 3.27 vs. 40.09 +/- 4.14) still remained in the TRH-implanted groups. This report is the first to provide evidence in support of in situ microdisk pharmacotherapy for potential neuropeptide delivery in intractable epilepsy and possibly other neurological disorders.

Animals↗

PubMed1998

Cloning and characterization of vascular endothelial growth factor (VEGF) from zebrafish, Danio rerio.

We have cloned and sequenced a zebrafish (Danio rerio) Vascular Endothelial Growth Factor (vegf) cDNA. It encodes a precursor protein of 188 amino acids with a putative 23 amino acids signal peptide. Sequence comparison analysis indicates that the zebrafish vegf cDNA corresponds to the human VEGF165 isoform and shows about 52% identity to human VEGF165 at the amino acid level. A 2.8 kb vegf message RNA was detected in adult zebrafish by Northern blot analysis. Expression of vegf165 is also detected by RT-PCR in adult fish and throughout the zebrafish embryonic development. Whole mount in situ hybridization of zebrafish embryos indicates strong expression in four areas of the 18-19 h post-fertilization (hpf) embryo: within the anterior central nervous system in the prospective optic stalk, in mesoderm overlapping the bilaterally located merging heart fields, in mesoderm underlying and flanking the hindbrain posterior to rhombomere 4, and in medial regions of the somites. The study of vegf function in zebrafish embryonic vascular development will contribute to our understanding of the mechanisms of vertebrate endothelial cell differentiation and vasculature formation.

Amino Acid Sequence↗

PubMed1998

High speed separation of DNA fragments by capillary electrophoresis in poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock polymer.

The high speed separation of DNA fragments by using a triblock copolymer, 25% w/v F127 (PEO99PPO69PEO99 with PEO and PPO denoting polyethylene oxide and polypropylene oxide, respectively) which is easy to handle and does not need coating of the quartz capillary, has been investigated. Two ways to decrease the run time are presented: one is to shorten the effective capillary length and the other to increase the electric field strength. In a short capillary, the sieving ability of the separation medium versus the initial band width, and the band width spreading as a function of distance traveled dominate the resolution; at high electric field strength, Joule heating could deteriorate the separation. By taking both effects into account, the phi X174/HaeIII digest could be separated within 100 s by using an 8 mm effective length, 50 microns diameter capillary operating at 300 V/cm.

Bacteriophage phi X 174↗

PubMed1998

Nonallelism for the audiogenic seizure prone (Asp1) and the aryl hydrocarbon receptor (Ahr) loci in mice.

Previous studies showed an association between the Ahr locus on Chr 12 and a major gene, Asp1, that influences susceptibility to audiogenic seizures (AGS) in mice. Although the association was thought to involve close linkage, a pleiotropic effect of the Ahr locus on AGS susceptibility was not excluded. Two congenic strains, D2.B6N-Asp1b and the D2N.B6N-Ahrb1, were used to evaluate further the association between the Ahr and Asp1 loci. Both strains are genetically identical to the AGS susceptible DBA/2 (D2) strain except for a small amount of C57BL/6N (B6N) genome surrounding the Ahr locus and encompassing the Asp1 locus. The AGS susceptibility of both congenic strains is similar and significantly lower than that of the D2 strain. We found that the Ahr/Asp1 critical region encompasses 5.5-7.0 cM from the proximal microsatellite marker D12Mit153 to the distal marker D12Mitl12. The D2N.B6N-Ahrb1 expresses B6 alleles for all markers within the critical region, whereas the D2.B6N-Asp1b expresses the B6 allele only at the Asp1 locus. Furthermore, we determined that the D2.B6N-Asp1b mouse expresses both the D2 phenotype and genotype at the Ahr locus, i.e., zoxazolamine paralysis and T to C and G to A transition mutations in the Ahr cDNA at bp sites 3330 and 3336, respectively. We therefore conclude that the Ahr and Asp1 loci are nonallelic and that the Ahr gene is excluded as a candidate for Asp1.

Alleles↗

PubMed1998

[Effect of changes of amino acids of N-terminal region of the mature protein on secretion of alpha-amylase in B. subtilis].

The mutant plasmid pAmy413C, in which G takes the place of A at the 271 position of alpha-amylase gene on the pAmy413 from B. licheniformis, was constructed by site-direct mutagenesis. At the N-terminus of the mature alpha-amylase, amino acid +2Asn was substituted by +3Asp in the wild type protein. Then, the alpha-amylase output of the mutant plasmid pAmy413C in B. subtilis was 2.02-2.57 times higher than that of the wild type pAmy413C in the same strain. The amino acid sequencing at the N-terminus of the matural alpha-amylase revealsed that the recognition site of signal peptidase I moved one amino acid upstream, from Ala-(+2)Asn to AlaAla-(+3) Asp. That is, the +2Asn of the wild type was changed to the +3Asp of the mutant. The secondary structural analysis showed that a 14-cycle structure formed in the alpha-amylase mRNA when the free energy was -51.7 kcal. In this case, the mutant is identical with the wild type. The difference between them is that G at 271 position is no longer paired with U at 211 position, hence, a G-overhang is formed. The secondary structural analysis of protein showed that one amino acid diminished in the turn structure of amino acid at 33-37 position, and this very amino acid is involed in an alpha-helix structure. In short, all the changes mentioned above in conformation and charged amino acids contribute to the increase in the protein secretion in B. subtilis.

Amino Acid Sequence↗

PubMed1997

Relation of donor age and preexisting coronary artery disease on angiography and intracoronary ultrasound to later development of accelerated allograft coronary artery disease.

OBJECTIVES: This study assessed the influence of donor age and preexisting donor coronary disease on the later development of allograft coronary artery disease, ischemic events and overall survival. BACKGROUND: The increasing demand for heart donors has led to a tendency to liberalize age criteria for donor acceptability. METHODS: A total of 233 consecutive heart transplant recipients who had baseline, early postoperative and follow-up coronary angiograms, as well as a subset of 47 patients with baseline intracoronary ultrasound imaging recordings, were analyzed (mean 3.8 years of follow-up). Patients were subclassified according to the presence of donor coronary artery disease on the baseline angiogram and stratified at age 40 years. RESULTS: patients without evidence of preexisting coronary artery disease on a baseline angiogram (n = 219) were significantly less likely to develop new disease than the 14 patients with preexisting coronary artery disease (p = 0.002). Although older donors exhibited earlier coronary artery disease than younger donors at 3 years of follow-up, there was no difference by 5 years (p = 0.25). There was no difference in survival or probability of developing ischemic events between the groups. Baseline ultrasound imaging revealed substantial disease in 7 of 9 older donated hearts, and in only 7 of 38 younger donated hearts (p = 0.002). Preexisting coronary artery disease, nonuse of calcium channel blocking agents, older donor age, posttransplantation cytomegalovirus infection, elevated very low density lipoprotein levels and previous ischemic heart disease in the recipient were significant predictors of allograft coronary artery disease. CONCLUSIONS: Heart donors with angiographic evidence of preexisting coronary artery disease and older donors are more likely to develop new allograft coronary artery disease by 3 years. However, there is no difference in survival or freedom from ischemic events between younger and older donors at a mean follow-up of 3.8 years.

Adolescent↗

PubMed1997

Comparison of sequences of RNAs 3 and 4 of rice stripe virus from China with those of Japanese isolates.

The sequences were determined of RNAs 3 and 4 of a Chinese isolate (Y) of rice stripe tenuivirus (RStV) and were compared with those of two RStV isolates (M and T) from Japan. Both RNAs of the Y isolate were longer than those of the M and T isolates. There was almost complete conservation in the 5' and 3' non-coding regions for each RNA between the isolates. The analogous ambisense coding regions for each isolate were exactly the same size and the sequences were highly conserved. The major differences were in the intergenic regions, the sizes of which accounted for the differences in size of each RNA of the three isolates. There were no obvious patterns of differences in comparisons of the two RNA over the three isolates. The significance of the similarities and differences in sequences of isolates of RStV separated by more than 3500 km is discussed.

Base Sequence↗

PubMed1997

[Fluconazole versus ketoconazole in systemic fungal infection: a double-blind randomized study].

We carried out a multiple-center study, including a double-blined randomized clinical trial on fluconazole (Flu, group A) and ketoconazole (Keto, group B) and an open trial on Flu only for evaluating the efficacy and safety of Flu in treating deep and shallow fungal infection. 222 patients participated in the study and most of them had severe underlying diseases. The dosage and therapeutic duration were as follows: Flu 200-400 mg daily for 1-8 weeks in 34 patients with fungal infection and 150 mg as a single dose in 30 patients with fungal vaginitis; Keto 400 mg daily for 1-8 weeks in 30 patients with fungal diseases and for 5 days in 30 patients with fungal vaginitis. In the trial 124 patients were randomized to receive either Flu (64 patients) or Keto (60). The cure rate in group A and B was 81.3% (52/64) and 58.0% (35/60) respectively (P < 0.05). The fungal eradication rates of the two groups were 85.7% and 70.0% (P > 0.05) respectively. 98 patients entered the open trial. They included fungal infection of the respiratory tract and urinary tract, cryptococal meningitis, fungal sepesis and systemic dissemination of mycosis and fungal vaginitis. 84 (85.7%) were cured. The fungal eradication rate of this group was 92.9%. The side-effect rates of the three groups were 3.1% (2/64), 5.0% (3/60) and 6.1% (6/98) respectively. They were mild and transient vomiting, nausea, and anorexia. In group B and the open group however, there was one case of ALT elevation in each group (P > 0.05). This study suggests that Flu is a safe, effective and useful drug for the treatment of severe fungal infection.

Adolescent↗

PubMed1997

[Treatment of posterior urethral break caused by pelvic fracture and inflammatory urethral stricture via laying three silicone tubers into urethra].

We investigated a new approach for the treatment of posterior urethral break caused by pelvic fracture and inflammatory urethral stricture. 7-10 days after the operation of urethral realignment on patients with urethral break caused by pelvic fracture or after forced dilatation of inflammatory urethral stricture, three silicone tubers were laid into urethra and kept there for three months. In 66 cases of urethral break, the cure rate (58/66) was 87.9%, the improving rate (2/66) 3.0% and the failure rate (6/66) 9.1%. In 15 cases of inflammatory urethral stricture, the recovery rate was 100%. In this group of 81 cases, the cure rate was 92.6% and failure rate was only 7.4%. This new therapeutic approach proved to be simple, safe and effective. It could also dramatically reduce the infection or the stricture of urethra.

Adolescent↗

PubMed1997

[The incidence of retinal detachment after extracapsular cataract extraction in high myopia].

PURPOSE: A retrospective study was performed to determine the incidence of retinal detachment after extracapsular cataract extraction in high myopia and the risk factors associated with the occurrence of retinal detachment. METHODS: Of the 463 patients (463 eyes) who had undergone extracapsular cataract extraction with or without intraocular lenses implant between July 1993 and January 1994, 90 patients companied with high myopia and the others were senior cataract. All patients had been followed up for 27 to 33 months. RESULTS: One (1.11%) developed retinal detachment in the patients with high myopia, and no retinal detachment occurred in the patients with senior cataract. The difference of the incidence of retinal detachment between two groups were no significant (P > 0.05), More myopic patients underwent Nd:YAG laser capsulotomy (P < 0.05). CONCLUSION: Comparing with intracapsular method, extracapsular cataract extraction decreased the risk of retinal detachment even in the high myopic patients. The risk factors for retinal detachment were young patients, long eye axis and posterior capsulotomy.

Aged↗

PubMed1996

Crystallization and preliminary X-ray diffraction studies of recombinant staphylokinase.

Staphylokinase, a fibrin-specific plasminogen activator, was highly expressed in Escherichia coli and purified by ion-exchange and gel-filtration chromatography. The purified recombinant staphylokinase was fully active and readily crystallized against 1.2 M sodium citrate in 100 mM Tris-HCl buffer at pH 8.0 using the hanging-drop method. Crystals of staphylokinase diffract to better than 2.2 A resolution. The crystal belongs to the tetragonal space group P4(1)2(1)2 or its enantiomorph with unit-cell parameters a = b = 67.5, c = 150.1 A. There are two molecules in the asymmetric unit. In this paper, we described the first crystallization of a kind of plasminogen activator and present the results of preliminary X-ray diffraction data from the native protein.

Journal Article↗

PubMed1996

Molecular replacement study on form-B monoclinic crystal of insulin.

The form-B monoclinic insulin crystal was obtained from the sodium citrate buffer with 1% zinc chloride, keeping phenolic content between 0.76% and 1.25%. Its space group is P2(1), cell constants are: a = 4.924 nm, b = 6.094 nm, c = 4.818 nm, beta = 95.8 degrees. There are 6 insulin molecules which form a hexamer. The initial phase was obtained by using rotation function program of X-PLOR program package and molecular packing program of our laboratory. The molecular model was chosen from 4 zinc bovine insulin hexamer. After the preliminary refinement by using the macromolecular rigid body refinement technique, the molecular model was further refined and adjusted by using the energy-minimizing stereochemically restrained least-squared refinement on the difference Fourier maps. The final R-factor is 22.4% at 0.3 nm resolution, the r.m.s. deviations from standard bond length and bond angle are 0.0022 nm and 4.7 degrees, respectively.

Crystallography↗

PubMed1996

Crystal structure of (L-Arg)-B0 bovine insulin at 0.21 nm resolution.

The crystal structure of (L-Arg)-B0 bovine insulin has been determined, using data to 0.21 nm and atomic parameters of 2Zn porcine insulin as a starting model, by the difference. Fourier method, the restrained least square method and X-PLOR package, interspersed with careful review of the electron density, to a final R-factor of 0.182 and r.m.s. deviation of 0.002 2 nm for the bond lengths and 4.3 degrees for the bond angles. The electron densities of additional (L-Arg)-B0 residues to B-chain N-terminus of two monomers in each asymmetric unit are very clear. The crystallographic micro-environment of the N-terminus of the B-chain is different from that of rhombohedral 2-zinc insulin.

Crystallization↗

PubMed1995

Influence of preexistent donor coronary artery disease on the progression of transplant vasculopathy. An intravascular ultrasound study.

BACKGROUND: Transplant vasculopathy (TxCAD) limits longterm survival of allograft recipients. The possibility that preexistent donor coronary disease (PEDD) might accelerate this process is of concern. The serial progression of sites with and without PEDD as assessed by intravascular ultrasonic imaging is explored in this study. METHODS AND RESULTS: Thirty patients with baseline intravascular imaging within 3 weeks of cardiac transplantation who had at least one annual follow-up study were included in this study. Vessel luminal area (LA), total area (TA), intimal index (II = TA - LA/TA), mean intimal thickness (MIT), and Stanford classification were expressed for each image site and for each patient at each study. Progression of sites and of patients with and without PEDD on the baseline study was compared. Patients with PEDD (n = 9) still had significantly more intimal disease than those without PEDD (n = 21) at the first follow-up study (MIT = 0.35 +/- 0.13 versus 0.13 +/- 0.11 mm; II = 0.29 +/- 0.11 versus 0.11 +/- 0.1; class = 3.7 +/- 0.5 versus 2.2 +/- 0.94; P < .001 for all comparisons). However, the increase in intimal thickness during the 1- year interval was not significantly different between the two groups. In 4 patients in whom both types of sites were present, no difference in progression was found. Data were similar for patients and sites studied over > 1 year. CONCLUSIONS: PEDD does not accelerate the progression of TxCAD within the first few years after cardiac transplantation. The pathophysiology of TxCAD is most likely immune mediated and does not seem to be accelerated by native coronary artery disease.

Adult↗

PubMed1995

Application of chiral gas chromatography with electroantennographic detection to the determination of the stereochemistry of a cockroach sex pheromone.

The coupling of an electroantennographic detector to a chiral capillary gas chromatographic system provides a highly sensitive technique for the determination of pheromone stereochemistry. Electronic modification of the usual electroantennographic detector enables the detector to respond to the relatively broad peaks produced by chiral gas chromatographic systems. By using this methodology, supellapyrone, a female sex pheromone of the brownbanded cockroach Supella longipalpa (Orthoptera: Blattellidae), is shown to be 5-(2'R,4'R-dimethylheptanyl)-3-methyl-2H-pyran-2-one.

Animals↗

PubMed1995

The crystal structure of deshexapeptide (B25-B30) insulin at 0.25 nm resolution.

The determination of deshexapeptide (B25-B30) insulin (DHI) was divided into two steps. At the first step, the rough structure model of DHI molecule was determined by using the molecular replacement method associated with the molecular close-packing method at 0.30 nm resolution based on the reflection data collected on four-cycle diffractometer. At the second step, the DHI model was adjusted and refined at 0.25 nm resolution based on the data collected on Area Detector. 40 water molecules were determined during the refinement, the final R-factor is 0.185 with R.M.S. deviation of 0.002 nm for bond lengths and 1.9 degrees for bond angles. The differences in conformation and function of DHI with other insulin analogues were compared and discussed.

Insulin↗

PubMed1995

[Pharmacokinetics of ciprofloxacin injection in healthy volunteers].

The results of pharmacokinetic study of intravenous infusion ciprofloxacin in normal male volunteers were presented. Serum and urine concentrations of ciprofloxacin were determined by high performance liquid chromatography. The single dose 200 mg iv concentration-time curve fitted to two-compartment open model in eight volunteers. Its main pharmacokinetic parameters were: C0 4.61 +/- 1.64 mg/L, t1/2 beta 3.86 +/- 0.67 h and AUC 7.06 +/- 1.21 mg/L.h. The urinary recovery rate of ciprofloxacin over 12 h after dosing was 60.85%.

Adult↗