Biomedical subjects

P Huang

Publications and source records attributed to P Huang.

At least 145 records · Page 8Linked to original sources

PubMed1997

Protein digest analysis by pressurized capillary electrochromatography using an ion trap storage/reflectron time-of-flight mass detector.

Pressurized capillary electrochromatography (pCEC) has been coupled to an ion trap storage/reflectron time-of-flight mass spectrometer for the analysis of peptide mixtures and protein digests. Taking advantage of the electroosmotic flow, high separation efficiency has been achieved in pCEC due to a relatively flat flow profile and the use of smaller packing materials. A supplementary pressure was used in these experiments which suppressed bubble formation and also allowed the tuning of the elution of peptides using the electrical field. In this work, a fast separation of a six-peptide mixture has been successfully performed. Using columns only 6 cm long, a tryptic digest of bovine cytochrome c was fully separated in around 14 min by properly tuning the applied voltage and the supplementary pressure. In addition, relatively complex protein digests, such as a tryptic digest of chicken ovalbumin, were analyzed using this pCEC/MS system, and more than 20 peaks were resolved in the total ion current chromatogram within 17 min. The use of an ion trap storage/reflectron time-of-flight mass spectrometer as an on-line detector further increased the resolving power of the pCEC by unambiguously identifying coeluting components. The nonscanning property of the time-of flight mass analyzer and the ion signal integration capability of the ion trap were successfully combined to provide rapid and sensitive full-mass range detection in these experiments.

Amino Acid Sequence↗

PubMed1997

Differential incorporation of ara-C, gemcitabine, and fludarabine into replicating and repairing DNA in proliferating human leukemia cells.

The major actions of nucleoside analogs such as arabinosylcytosine (ara-C) and fludarabine occurs after their incorporation into DNA, during either replication or repair synthesis. The metabolic salvage and DNA incorporation of the normal nucleoside, deoxycytidine, is functionally compartmentalized toward repair synthesis in a process regulated by ribonucleotide reductase. The aim of this study was to investigate the metabolic pathways by which nucleoside analogs that do (fludarabine, gemcitabine) or do not (ara-C) affect ribonucleotide reductase are incorporated into DNA in proliferating human leukemia cells. Using alkaline density-gradient centrifugation to separate repaired DNA from replicating DNA and unreplicated parental DNA strands, approximately 60% of ara-C nucleotide in DNA was incorporated by repair synthesis in CCRF-CEM cells; the remainder was incorporated by replication. In contrast, fludarabine and gemcitabine, nucleosides that inhibit ribonucleotide reductase and decreased deoxynucleotide pools, were incorporated mainly within replicating DNA. Hydroxyurea also depleted deoxynucleotide pools and increased the incorporation of ara-C into DNA by replicative synthesis. Stimulation of DNA repair activity by UV irradiation selectively enhanced the incorporation of all nucleosides tested through repair synthesis. These findings suggest that the pathways by which therapeutically useful nucleoside analogs are incorporated into DNA are affected by cellular dNTP pools from de novo synthesis and by the relative activities of DNA repair and replication. The antitumor activity of these drugs may be enhanced by combination with either ribonucleotide reductase inhibitors to increase their incorporation into replicating DNA or with agents that induce DNA damage and evoke the DNA repair process.

Antineoplastic Agents↗

PubMed1997

G alpha(o) is necessary for muscarinic regulation of Ca2+ channels in mouse heart.

Heterotrimeric G proteins, composed of G alpha and G betagamma subunits, transmit signals from cell surface receptors to cellular effector enzymes and ion channels. The G alpha(o) protein is the most abundant G alpha subtype in the nervous system, but it is also found in the heart. Its function is not completely known, although it is required for regulation of N-type Ca2+ channels in GH3 cells and also interacts with GAP43, a major protein in growth cones, suggesting a role in neuronal pathfinding. To analyze the function of G alpha(o), we have generated mice lacking both isoforms of G alpha(o) by homologous recombination. Surprisingly, the nervous system is grossly intact, despite the fact that G alpha(o) makes up 0.2-0.5% of brain particulate protein and 10% of the growth cone membrane. The G alpha(o)-/- mice do suffer tremors and occasional seizures, but there is no obvious histologic abnormality in the nervous system. In contrast, G alpha(o)-/- mice have a clear and specific defect in ion channel regulation in the heart. Normal muscarinic regulation of L-type calcium channels in ventricular myocytes is absent in the mutant mice. The L-type calcium channel responds normally to isoproterenol, but there is no evident muscarinic inhibition. Muscarinic regulation of atrial K+ channels is normal, as is the electrocardiogram. The levels of other G alpha subunits (G alpha(s), G alpha(q), and G alpha(i)) are unchanged in the hearts of G alpha(o)-/- mice, but the amount of G betagamma is decreased. Whichever subunit, G alpha(o) or G betagamma, carries the signal forward, these studies show that muscarinic inhibition of L-type Ca2+ channels requires coupling of the muscarinic receptor to G alpha(o). Other cardiac G alpha subunits cannot substitute.

Acetylcholine↗

PubMed1997

Open-tubular capillary electrochromatography with an on-line ion trap storage/reflectron time-of-flight mass detector for ultrafast peptide mixture analysis.

In this work, a novel open-tubular column (OTC) capillary electrochromatography (CEC) system has been coupled to an on-line ion trap storage/reflectron time-of-flight mass spectrometer for ultrafast peptide mixture analysis. Reversed-phase OTCs prepared by the sol-gel process were coated with an amine, which greatly enhanced the electroosmotic flow in an acidic buffer solution and considerably reduced nonspecific adsorption between the peptides and the column wall. A six-peptide mixture could be separated to baseline within 3 min on this system. A full mass range detection speed of 8 Hz was used in all these experiments, which was sufficiently rapid to maintain the high efficiency of ultrafast separations. Because of the high duty cycle of the mass spectrometer and the column path length-independent concentration-sensitive feature of the electrospray ionization process, high-quality total ion chromatograms could be obtained with injections of only 1-2 fmol of peptide samples. A concentration limit of detection of 1 x 10(-6) M was also achieved due to the preconcentration capability of CEC. In addition, a novel gradient CEC device was demonstrated which did not result in a pressure-driven flow. A tryptic digest of horse heart myoglobin was successfully separated on the gradient CEC system within 6 min. The use of the mass spectrometer increased the resolving power of this system by clearly identifying coeluting components.

Amino Acid Sequence↗

PubMed1997

Platelet deposition on ePTFE grafts coated with fibrin glue with or without FGF-1 and heparin.

INTRODUCTION: The disappointing long-term patency of small-caliber prosthetic grafts may be due in part to early thrombogenicity of the prosthetic surface. We previously reported that the coating of expanded polytetrafluoroethylene (ePTFE) with fibrin glue (FG) containing fibroblast growth factor type 1 (FGF-1) and heparin accelerated spontaneous endothelial coverage of ePTFE grafts in an animal model; however, FG's effect on platelets remains unclear. This study was done to evaluate platelet deposition onto GF/FGF-1/ heparin-coated vs FG-coated vs whole-blood-preclotted ePTFE surfaces. METHODS: Twelve 5-cm ePTFE grafts were treated either with FG (thrombin, 0.32 U/ ml, and fibrinogen, 32.1 mg/ml, n = 8) or with FG containing FGF-1 (11 ng/ml) plus heparin (250U/ml, n = 4). Twelve control ePTFE grafts were preclotted with canine (n = 8) or human (n = 4) whole blood. These treated grafts were placed onto a loop pulsatile perfusion system in pairs (preclotted with either FG or FG/ FGF-1/heparin) and perfused with a M-199/10% FBS/ 111indium-labeled platelet suspension. After 60 min the grafts were gamma counted and CPM/mm2 were determined. RESULTS: In both trials, the preclotted ePTFE grafts demonstrated similarly increased platelet deposition when compared to grafts treated with FG/FGF-1/heparin or FG alone (P < 0.001 for each). CONCLUSION: The decrease in platelet deposition on the FG/FGF-1/ heparin-coated grafts vs preclotted grafts is not due to heparin and is not specific to canine or human platelets. FG-coated grafts may induce a decrease in early graft thrombogenicity when compared to whole blood preclotting.

Animals↗

PubMed1997

Fibrin glue containing fibroblast growth factor type 1 and heparin decreases platelet deposition.

BACKGROUND: The early success rates of endarterectomy and angioplasty are influenced by the thrombogenicity of the deendothelialized surface. We previously reported decreased platelet deposition after 30 and 120 minutes and after 28 days on expanded polytetrafluoroethylene (ePTFE) grafts coated with fibrin glue (FG) containing fibroblast growth factor type 1 (FGF-1) and heparin in canine aortoiliac bypass grafts when compared with control uncoated grafts. The FG/FGF-1/heparin coating has been shown to enhance spontaneous endothelialization at 28 days in canine ePTFE bypass grafts. The current study evaluates the thrombogenicity of this FG/FGF-1/heparin suspension applied to a balloon de-endothelialization model of endarterectomy in canine carotid arteries. METHODS: Nine dogs underwent bilateral, deendothelialization balloon injury to 6-cm segments of their carotid arteries. Fibrin glue (fibrinogen 32.1 mg/mL + thrombin 0.32 U/mL) containing FGF-1 (11 ng/mL) and heparin (250 U/mL) was applied to the luminal surface of one carotid artery in each dog. Both femoral arteries were circumferentially dissected but not balloon injured; one femoral artery was clamped for the same period as the carotid arteries. In the 6 acute dogs, 10 minutes prior to the restitution of flow in both carotid arteries and one femoral artery, 4 to 8 x 10(9) (111)In-labelled autologous platelets were injected intravenously. Four-cm segments of both carotid and femoral arteries were excised after 15 or 120 minutes of circulation (n = 3/time/artery, 24 arteries). In the 3 chronic dogs, the radiolabelled platelets were injected 30 days after carotid injury. The carotid and femoral vessels were then excised after 120 minutes of perfusion. Radioactive platelet deposition was quantitated by gamma counting. RESULTS: After 2 hours, the injured carotid arteries demonstrated significantly more platelet deposition than either uninjured femoral artery controls (P < 0.001). There was also a significant 45.2% decrease (P = 0.008) in platelet deposition on the balloon injured carotid arteries treated with FG/FGF-1/heparin when compared with balloon injured carotid arteries alone. At 30 days there was an insignificant trend toward decreased thrombogenicity in the FG/FGF-1/heparin treated injured carotids. CONCLUSION: Surface coating with FG/FGF-1/heparin significantly decreases platelet deposition on balloon injured canine carotid arteries after 2 hours of perfusion and may be clinically applicable in endarterectomy and angioplasty procedures. The long-term induction of reendothelialization of arterial surfaces by this technique is under investigation.

Animals↗

PubMed1997

Fibrin glue containing fibroblast growth factor type 1 and heparin with autologous endothelial cells reduces intimal hyperplasia in a canine carotid artery balloon injury model.

PURPOSE: Intimal hyperplasia plagues all types of vascular intervention. Early confluent re-endothelialization may attenuate the smooth muscle cell (SMC) proliferative response. We previously reported that fibroblast growth factor type 1 (FGF-1) and heparin at relative concentrations of 10 ng/ml:250 U/ml delivered in a fibrin glue (FG) suspension can selectively stimulate endothelial cells (EC) and inhibit SMC proliferation in cell culture. This current study evaluates this surface treatment with and without seeded autologous ECs on intimal hyperplasia in a canine carotid artery balloon injury model. METHODS: Twenty-nine adult dogs underwent bilateral balloon injury to a 6 cm segment of their carotid arteries. The injury resulted in a reproducible removal of the intima and 4 to 6 medial lamellae. Nine dogs were used in part I to determine the percent retention of FGF-1 and EC when applied in a FG suspension to the balloon-injured carotid arteries. Part 2 used the remaining 20 dogs to determine the effect of this surface treatment on intimal hyperplasia. In 10 group I dogs, FG (fibrinogen 32.1 mg/ml and thrombin 0.32 U/ml) containing FGF-1 (11 ng/ml) and heparin (250 U/ml) was applied to the luminal surface of one carotid artery, whereas the contralateral carotid artery underwent balloon injury alone. In 10 group II dogs, an identical FG preparation with FGF-1 and heparin was applied to the surface of one carotid artery, whereas the contralateral carotid artery received FG/FGF-1/heparin that also contained autologous ECs (P3; 5 x 10(4) to 10 x 10(4) cells/cm2). Five dogs from both group I and group II were killed at 10 days and the remaining 10 dogs at 30 days. Histologic analysis and computerized morphometric analysis were used to determine intimal and medial thickness and area, percent endothelialization, and medial SMC proliferative rate. RESULTS: There was no measurable neointima in any 10-day dog. There was no difference in neointimal area between the treatments in group I 30-day dogs. There was a significant decrease in maximal neointimal area, intima/media thickness ratio, and intima/media area ratio in group II 30-day dogs that were treated with FG/FGF-1/heparin plus EC. There was an insignificant increase in percent EC coverage and an insignificant decrease in medial SMC proliferative rate in group II 10-day dogs treated with FG/FGF-1/heparin plus EC. CONCLUSIONS: In this canine carotid model, FG with FGF-1 and heparin did not induce significant intimal or medial thickening after 10 or 30 days when compared with vessels that were only balloon-injured. The seeding of autologous ECs within the FG/FGF-1/heparin suspension caused a reduction in neointima formation with no concomitant medial thickening 30 days after injury. The use of FG to locally deliver FGF-1 and ECs may have clinical relevance in the inhibition of intimal hyperplasia.

Animals↗

PubMed1997

Development of a common 3D pharmacophore for delta-opioid recognition from peptides and non-peptides using a novel computer program.

A unified three-dimensional (3D) pharmacophore for recognition of the delta-opioid receptor by families of structurally diverse delta-opioid ligands, including peptides and non-peptides, has been determined. An additional structural feature required for delta-selectivity was also characterized using a subset of these ligands that are highly selective for the delta-opioid receptor. To obtain these pharmacophores, we have used a recently developed computer program that performs systematic and automated comparisons of molecules to determine whether any common 3D relationships exist among candidate recognition moieties in high-affinity analogs. All the low-energy conformations of each ligand are included in these comparisons. The program developed should be applicable in general to molecular superimposition problems in rational drug design and to develop both 3D recognition and activation pharmacophores for any receptor for which high- and low-affinity analogs and agonists and antagonists have been identified.

Base Sequence↗

PubMed1997

Lipoprotein lipase gene polymorphisms in ischaemic stroke and carotid stenosis.

Ischaemic stroke is pathogenetically heterogeneous, but there is strong evidence that genetic as well as environment factors contribute to the risk of the individual. Here we report the similar distribution of polymorphic markers of the lipoprotein lipase (LPL) gene in 128 patients with ischaemic stroke, 56 patients with carotid artery stenosis and 95 healthy control subjects, in spite of a significant influence of the Asn291-->Ser mutation on serum levels of triglycerides. We conclude that these LPL polymorphisms do not contribute greatly to the overall risk of ischaemic stroke in the general population.

Aged↗

PubMed1997

[One-year-result of excimer laser for photorefractive keratectomy in very high myopia].

We corrected 53 cases (84 eyes) of very high myopia using photorefractive keratectomy (PRK) with VISX 20/20 excimer laser, and followed up the cases more than one year. The rates of visual acuity more than or equal to 0.5 or 1.0 were 81.0% and 23.9%, 75.0% eyes were within +/- 2.00 diopter of the desired emmetropia. Grade 2 or more severe corneal haze were presented in 13.1% eyes. PRK with VISX 20/20 excimer laser may be an effective method to correct very high myopia from -10.00 to -16.00 diopters.

Adolescent↗

PubMed1997

[Photorefractive keratectomy to correct myopic astigmatism].

The VISX 20/20 excimer laser was used to treat 260 eyes with myopia and myopic astigmatism of 166 patients. All patients were followed up for one year. The diopter of preoperative astigmatism was from -0.25-(- 4.00 D (-1.00 +/- 0.62 D). The diopter was lowered to -0.07 +/- 0.40 D at 6 months postoperatively (P < 0.05) and -0.06 +/- 0.39 D at 12 months postoperatively (P < 0.01). Photorefractive keratectomy (PRK) is effective and safe for myopic astigmatism.

Adolescent↗

PubMed1997

[Mutiple factors analysis of the effects of excimer laser photorefractive keratectomy].

PURPOSE: To observe the effect of excimer laser photorefractive keratectomy (PRK) correcting myopia and astigmatism, and to study the related factors. METHOD: PRK was performed with the aim to correct myopia errors from 1.00 to 16.00 diopters on 529 myopia eyes (306 patients). All eyes were divided into two groups: Group I: -1.00-6.00 D(294 eyes); group II: -6.25-16.00 D(235 eyes). All the patients were followed up for 3 to 12 months. RESULTS: At postoperative 12 months the rates of uncorrected visual acuity more than or equal to 10/20 or 20/20 were 97.5%, 77.5% in group I, and 80.3%, 32.8% in group II respectively; 92.5% of eyes were within +/- 1.00 diopter of the desired emmetropia in group I, but 42.6% in group II; The influential factors of changes of postoperative diopters was the severity of corneal haze, methods of removing corneal epithelium, intraocular pressure, the central corneal thickness. CONCLUSION: The excimer laser PRK is regarded to be a very predictable, safe, stable, and effective method to correct myopia up to -6.00 D. Prior to operation, the plan would be disigned according to diopters, ages, corneal thickness intraocular pressure. During operation, the corneal epithelium bad better to be removed by laser.

Astigmatism↗

PubMed1997

[Isolation and structure elucidation of longshengensin A from Peucedanum longshengense].

Two compounds were isolated from Peucedanum longshengense Shan et Sheh for the first time. Their structures were identified as longshengensin A (I) and mannitol (II) by physico-chemical constants and spectral analyses (UV, IR, MS, NMR and 2D-NMR). I is a new compound with the structure of (-)-3' (s)-acetyloxy-4' (s)-angeloyloxy-3', 4'-dihydroseselin and named longshengensin A. Its absolute configurations were determined by chemical correlation with khellactone.

Apiaceae↗

PubMed1997

[Triterpene acids from the barks of Illicium difengpi].

Four compounds were isolated from the traditional Chinese medicine "Difengpi", barks of Illicium difengpi K.I.B. et K.I.M. They were identified as 3 beta-O-acetyl-mangiferolic acid (I), mangiferonic acid (II), mangiferolic acid (III) and butulinic acid (IV) by physico-chemical constants and spectral analyses (UV, IR, EIMS, 1HNMR, 13CNMR, NOEDE and 2D NMR). Compound I is a new compound. These triterpene acids (I-IV) were isolated from Illicium genus for the first time.

Drugs, Chinese Herbal↗

PubMed1997

[Content determination of total coumarin of qian-hu].

The total content of coumarin in Qian-Hu was determined by UV spectrometry. The 25 samples which derived from different places of production were included eleven varieties. The results were found to have max = 322 nm, 99.18% of recovery rate and 2.08% of RSD.

Coumarins↗

PubMed1997

[Studies on the pharmacognosy of Cortex Illicii and its adulterants].

The traditional Chinese Medicine Cortex Illicii and its adulterants were studied on textual identification, botanical origin, morphological and histological characters. The TLC and UV spertra methods were established to separate and estimate Difengpin, Magnolol and beta-sitosterol in Cortex Illicii and its products.

Chromatography, Thin Layer↗

PubMed1997

A large adrenal pseudocyst mimicking malignant intraabdominal tumor: a case report.

An abdominal mass was found in an apparently healthy 66-year-old man during he was undergoing a routine physical check-up. Intravenous pyelography showed a huge suprarenal cyst displacing the left kidney. Both kidneys had normal renal function. The tumor was removed transperitoneally. It contained 1600 ml hemorrhagic fluid and had small golden nodules on the inner cystic surface. Microscopically, adrenal cortical tissue was present in groups or scattered along the cystic wall, which was compatible with the diagnosis of pseudocyst. No lining epithelium was present. The differential diagnosis, pathogenesis, management, and the general features of adrenal pseudocysts were discussed.

Abdominal Neoplasms↗

PubMed1997

The study of IL-1 beta, TNF-alpha, IL-6 gene expression and plasma levels on hemodialysis before and after dialyzer reuse.

OBJECTIVE: To investigate the biocompatibility of dialyzer reuse. METHODS: Twenty-two hemodialysis patients were randomized into cuprophan (CU, 7), polymethylmethacrylate (PMMA, 7) and polysulphone (PS, 8) membrane groups to observe IL-1 beta, TNF-alpha, IL-6 gene expression and their plasma levels by using themselves as control with enzyme-linked immunosorbent assay (ELISA), reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. RESULTS: Plasma levels of interlukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) were 14.07 +/- 3.32 pg/ml, 67.41 +/- 19.79 pg/ml, 83.67 +/- 40.34 pg/ml; 12.80 +/- 3.01 pg/ml, 49.65 +/- 9.75 pg/ml, 33.36 +/- 12.14 pg/ml and 14.41 +/- 3.16 pg/ml, 80.56 +/- 23.22 pg/ml, 48.14 +/- 16.01 pg/ml, respectively, after patients dialyzed with CU, PMMA and PS membranes. Plasma cytokine levels decreased after reuse compared with those before reuse in each group. But no significant difference was found between them (P > 0.05); the levels of IL-1 beta, TNF-alpha, IL-6 gene expression after reuse were 5.61 +/- 0.33, 2.11 +/- 0.12, 5.04 +/- 0.19%; 2.43 +/- 0.19, 1.29 +/- 0.11, 3.48 +/- 0.20% and 2.48 +/- 0.20, 1.24 +/- 0.11, 3.22 +/- 0.20% respectively by in situ hybridization, and 0.92 +/- 0.07, 0.63 +/- 0.05, 0.53 +/- 0.05; 0.61 +/- 0.06, 0.47 +/- 0.04, 0.37 +/- 0.03 and 0.59 +/- 0.05, 0.44 +/- 0.04, 0.38 +/- 0.03 by RT-PCR, respectively. After reuse there was significant decrease as compared with that before reuse (P < 0.001, P < 0.005 and P < 0.05, respectively). CONCLUSIONS: This suggested reprocessing dialyzer with formaldehyde reduced cytokine release and gene expression in peripheral blood mononuclear cells and enhanced dialyzer biocompatibility. It would be beneficial to reduce the dialysis cost and may reduce the complication related to a long term hemodialysis.

Adult↗