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Biomedical subjects

J Han

Publications and source records attributed to J Han.

At least 145 records · Page 8Linked to original sources
PubMed2000

Asymmetric synthesis of 2,3-methanoleucine stereoisomers from common intermediates.

2,3-Methanoamino acids are useful probes for studying the bioactive conformation of peptides and for investigating the effect of local conformational constraints on the activity of peptidomimetics. We synthesized all four stereoisomers of Cbz-protected 2, 3-methanoleucine for incorporation into peptidomimetic inhibitors of calpain. While the synthesis of 2,3-methanoamino acids has been previously reported, our procedure offers a versatile route in which the pair of diastereomers of each geometric isomer was synthesized from a common intermediate.

Amino Acids↗
PubMed2000

CD36 in atherosclerosis. The role of a class B macrophage scavenger receptor.

CD36, an 88 kD transmembrane glycoprotein, is an important receptor for oxidized lipoproteins. Unlike the LDL receptor, expression of CD36 is upregulated by this pro-atherogenic particle, and binding and uptake perpetuates a cycle of lipid accumulation and receptor expression. This effect is, in part, mediated by the transcription factor, peroxisome proliferator activated receptor-gamma (PPAR gamma), and its ligands. We have found that specific inhibitors of protein kinase C (PKC) reduce basal mRNA expression of CD36 and block induction of CD36 mRNA and protein by oxidized LDL (OxLDL) and a PPAR gamma ligand. In addition, PKC inhibitors block both PPAR gamma mRNA and protein expression. These results suggest that activation of CD36 gene expression by OxLDL involves activation and translocation of PKC with subsequent PPAR gamma activation. More recently, we have generated a mouse null for CD36, and crossed it with the atherogenic Apo E null strain. Evaluation of lesion development in these animals will allow us to assess the in vivo contribution of CD36 to the pathogenesis of atherosclerosis.

Animals↗
PubMed2000

Iron deficiency alters H- and L-ferritin expression in rat brain.

Ferritin (Ft) H and L subunits are independently regulated proteins with both transcriptional and translational regulation in response to cellular iron levels. While the heterogeneous distribution of ferritin and iron in the brain is now well established, the relative response of each subunit to iron deficiency and iron supplementation, is not well defined. Weanling male Sprague-Dawley rats (n=12 per group) were randomly assigned to an iron deficient (3.5 mg Fe/kg diet), control (35 mg Fe/kg diet) or supplemented (350 mg Fe/kg diet) diet for six weeks. The H-/L-ferritin subunit ratio and mRNA levels were determined. Overall, the protein ratio in control rats of H to L was approximately 45:1 compared to a ratio >60:1 in iron deficiency but the absolute amounts of each subunit varied greatly from one brain region to another. The ratio of H-:L-ferritin mRNA was 6:1 and was not affected by dietary iron deficiency in contrast to a potent effect on mRNA levels in liver. Severe iron deficiency reduced brain ferritin H protein levels significantly in all regions, whereas only ferritin L levels in striatum, substantia nigra and pons were affected by iron deficiency. Supplemental dietary iron increased both ferritin subunits, with the largest increase (50%) in the hippocampus. These data indicate that ferritin H and L subunits within the brain respond differently to iron status and suggest post transcription regulation as a key event.

Animals↗
PubMed2000

Changes in stroke index measured by impedance cardiography in a human model of moderate acute blood loss

Early detection of acute hemorrhage is problematic because changes in traditional parameters such as heart rate and blood pressure are notoriously unreliable. OBJECTIVE: To observe the effect of acute, moderate blood loss on stroke index (SI) as measured non-invasively by impedance cardiography. METHODS: Five healthy, adult volunteers were phlebotomized 590 mL over ten minutes. The volume of blood loss was expressed as a percent of estimated total blood volume (TBV) according to the formula TBV = (weight in kg) x (70 mL/kg). Stroke index was measured in a fixed, reclining position before (SI #1) and after (SI #2) phlebotomy, using the BioZ.com (Cardiodynamics International Corporation, San Diego, CA) thoracic bioimpedance monitor. Absolute and relative changes were calculated. RESULTS: In each volunteer, a fall in SI was noted after phlebotomy. The percent change in SI ranged from 8% to 18% (table 15-1). There appeared to be a correlation between blood loss as a percent of estimated total blood volume and the percent decline in SI among these volunteers. CONCLUSIONS: Impedance cardiography reliably detected moderate acute blood loss in this small set of healthy, adult volunteers. If these results can be quantified and validated prospectively in a larger population, SI may prove to be a valuable, non-invasive parameter for detection of early hemorrhage shock.

Journal Article↗
PubMed2000

[Study of an in-vivo and real-time method to measure blood viscosity].

The traditional methods to measure blood viscosity are out-line. They have the disadvantages of long measurement time, many disturbance factors during measurement, the damage to blood sample, and etc. So rapidity, accuracy and repeatability are not satisfactory. A new method to measure blood viscosity is proposed in this paper, which uses needle instead of capillary and can measure blood viscosity during collecting blood. Owing to the advantages of small amount of blood sample, rapidity and repeatability, the new method is of value for clinical application.

Animals↗
PubMed2000

[A functional evaluation on peripheral nerve regeneration enhanced by targeted muscular injection of ciliary neurotrophic factor].

OBJECTIVE: To investigate the effects of targeted muscular injection of ciliary neurotrophic factor (CNTF) on the regeneration of injured peripheral nerves. METHODS: The left sciatic nerves of 80 Sprague-Dawley rats were excised to form 6 mm defect and the two ends were bridged by silicone tubes, they were randomly divided into two groups, CNTF group and normal saline (NS) group. The CNTF group was given recombinant human CNTF, 1 mg/kg every other day for 30 days, and the NS group was given equal quantity of normal saline as NS group. The sciatic nerve functional index (SFI), electrophysiological assessment, morphometric analysis of axons, and choleratoxin horseradish peroxidase (CB-HRP) retrograde-labelling were measured postoperatively. RESULTS: The SFI, electrophysiological parameters (nerve conduction velocity, latency and amplitude of compound muscle action potentials), myelinated axons counts, mean axons diameters and myelin sheath thickness, number of CB-HRP labelled ventral horn motor neurons of spinal cord were significantly higher in CNTF group than that of NS group. CONCLUSION: Targeted muscular injection of CNTF can promote the regeneration of peripheral nerve and improve the nerve functional recovery.

Animals↗
PubMed2000

[Effect of 2/100 Hz transcutaneous electrical nerve stimulation on sexual dysfunction and serum sex hormone of heroin addicts].

OBJECTIVE: To evaluate the effect of 2/100 Hz electrical stimulation produced by Han's acupoint nerve stimulator (HANS) in treating heroin induced sex dysfunction. METHODS: Thirty-three heroin addicts were randomly divided into 2 groups to receive either buprenorphine (BPN group, n = 16) or HANS plus small dose of BPN (HANS group, n = 17) for 14 days. The doses of BPN were tailored according to individual requirement that could totally abolish withdrawal syndrome. The frequency of HANS was 2 Hz and 100 Hz shifting automatically, each lasting for 3 seconds. The stimulation was applied to 8 acupoints, the Hegu and Laogong of one upper limb, Neiguan and Waiguan of another limb, Sanyinjiao and Xingjian of both lower limbs, for 30 min. The therapy was carried out 3-4 times per day in the initial two weeks of treatment, and reduced to 1-2 times per day in the following 2 weeks. RESULTS: (1) The urine analysis for morphine in both groups turned to negative 14 days after treatment. (2) After 2 weeks of treatment, the composite score (Visual Analog Scale, VAS) of sexual function in HANS group showed a 102% increase (P < 0.01) compared with before treatment and was 107% of that in the BPN group (P < 0.01). (3) After 4 weeks treatment the serum concentration of luteinizing hormone (LH) and testosterone (T) in the HANS group showed a 137% and 118% increase respectively compared with those before treatment (P < 0.05), and the level of LH was 79.6% of that in the BPN group (P < 0.05). CONCLUSION: The 2/100 Hz transcutaneous electrical stimulation produced by Han's acupoint nerve stimulator could improve the recovery of sexual function and raise the serum concentration of LH and T in heroin addicts.

Adult↗
PubMed2000

[Modified vascular endothelia growth factor receptor-mediated targeting nonviral gene delivery system and in vivo beta-gal transducing experiment].

OBJECTIVE: To investigate whether the modified vascular endothelial growth factor (VEGF) receptor-mediated targeting nonviral gene delivery system is efficient in transducing exogenous gene. METHODS: We detected the expression of VEGF receptor on some tumor models by immunohistochemistry at first and selected nine models, i.e. SMMC-7721, SK-OV-3, H128, SPC-A1, LoVo, MKN-45, BCaP-37, A375, cervical cancer xenograft and hepatoma xenograft. Then we prepared two complexes, GV1-P.L./beta-gal and GV2-P.L./beta-gal, and injected the two complexes subcutaneously into nude mice around the tumor. The expression of the reporter gene was observed in the vascular endothelial cells and some tumor cells with highly expressed VEGF receptor. RESULTS: GV2 gene delivery system could transduce exogenous gene into vascular endothelial cells and subcutaneously transplanted tumors such as SK-OV-3, and cervical xenograft which were rich of VEGF receptor on the surface of the tumor cell. The expression reached a high level at day 3 and decreased eventually until the 3(rd) week. There was no expression in the heart and lung but low expression was seen in the spleen. GV1 gene delivery system also transduced exogenous gene into the endothelial cells but with low efficiency. CONCLUSION: This system can specifically transduce beta-gal to cells rich of VEGF receptor but not to cells with undetectable VEGF receptor. The targetability of this modified system is increased as compared to the system previously reported.

Animals↗
PubMed2000

[Comparison of TIPS, a modified Sugiura procedure and TIPS plus a modified Sugiura procedure for portal hypertension].

OBJECTIVE: Transjugular intrahepatic portosystemic shunts (TIPS), a modified Sugiura procedure and TIPS plus a modified Sugiura procedure were compared to evaluate their clinical results in treatment of portal hypertension. METHODS: Ninety patients with portal hypertension respectively underwen TIPS (group I, n = 30), a modified Sugiura procedure (group II, n = 30) and TIPS plus a modified Sugiura procedure (group III, n = 30). The rates of rebleeding and encephalopathy, and the mortality of patients with portal hypertension were observed. RESULTS: The early postoperative complications were observed in 23.33% of the patients in group I, in 30.0% of those in group II, and in 20.0% of those in group III. The early postoperative rates of rebleeding were 6.67% in group I, 10% in group II, and 0% in group III. Hepatic encephalopathy was seen in 16.67% of the patients in group I, 0% in group II and 13.33% in group III. The early mortality was 3.33% in group I. During follow-up for 1 - 36 months, the rates of rebleeding were 34.48% in group I, 33.33% in group II, and 3.33% in group III. The rates of encephalopathy and mortality were respectively 17.20% and 20.69% in group I, 3.33% and 13.33% in group II, 3.33% and 3.33% in group III. The shunt patency in group III was higher than that in group I. CONCLUSION: Combination of TIPS and a modified Sugiura procedure can be effective to prevent and treat variceal bleeding.

Adult↗
PubMed2000

[Establishment and biological characteristics of a novel erythroleukemia cell line (HIE1)].

OBJECTIVE: To establish a novel leukemia cell line and characterize its biological characteristics. METHOD: The cell line was established by liquid cell culture. The genetic marker was analyzed by R-banding and reverse transcriptase-polymerase chain reaction (RT-PCR), cell morphology by microscopy, electron microscopy and histochemical staining, cell surface antigen by monoclonal antibody, hemoglobin by hyperomethemoglobin measurement and electrophoresis, erythroid differentiation by benzidine-staining, and monocyte-macrophage differentiation by cell morphology and phagocytosis. RESULTS: A novel erythroleukemia cell line (HIE1), with original cell genetic marker (Ph chromosome, bcr/abl fusion gene rearrangement), was established from a CML patient in blast crisis, and has been passaged for over 60 generations. Myelomonocyte marker and hemoglycoprotein A were found on the cell surface. HIE1 cells contained hemoglobin, the same HbA and HbA(2) bands as in normal individuals were displayed by Hb electrophoresis. The benzidine positive HIE1 cells were induced after exposure to 3.6 x 10(-4) mmol/L Ara-C. When HIE1 cells were treated with 100 ng/ml PMA for 3 days, one third of the cells became spindle in shape, and 6.5% of the cells exert phagocytosis. The cells were classified into two types with Wright-staining: one showing light blue cytoplasm and a few of cells with basophilic granules, the other showing dark blue cytoplasm with vacuoles and pseudopods without granules. In addition, POX, SB, CE stains were negative, and AE, PAS, ACP stains positive. Colony formation of the cells was 37%, the cell doubling time was 22 - 24 hrs, and EB virus detection was positive. CONCLUSION: A novel erythroleukemia cell line with bcr/abl fusion gene and characteristics of myelomonocytic and erythroid cells was established.

Cell Differentiation↗
PubMed2000

[Treatment of acute lymphoblastic leukemia by autologous stem cell transplantation: an analysis of 30 cases].

OBJECTIVE: To evaluate the clinical outcome of autologous stem cell transplantation (ASCT) in acute lymphoblastic leukemia (ALL) and the affected factors. METHODS: Data of 30 ALL patients received ASCT in our hospital between July 1987 and December 1997 were retrospectively analyzed. Twenty-four of them were in the first complete remission (CR(1)) and six in the second complete remission (CR(2)) or early relapse (ER). Conditioning regimens were CTX 120 mg/kg + single total body irradiation 9 - 10 Gy (sTBI) or Bu 16 mg/kg of Mel 140 - 180 mg/m(2) + Ara-c 2 - 4 g/m(2). RESULTS: All patients reconstituted hematopoiesis. The median follow-up duration was 504 (18-3043) days. Transplant-related mortality was 10%. The probabilities of 3 year disease-free survival (DFS) for ALL in CR(1) and CR(2) were 67.7% +/- 10.3% and 16.7% +/- 15.2%, respectively (P = 0.00547); the 3 year DFS was significantly better with posttransplant treatment than without it (92.3% +/- 7.4% vs 50.0% +/- 17.7%, P = 0.0130). CONCLUSION: Acute lymphoblastic leukemia patients without HLA-matched related donor are recommended for ASCT in CR(1). To reduce relapse and improve the outcome, adoptive immunotherapy or maintenance chemotherapy should be given after ASCT.

Adolescent↗
PubMed2000

[Factor XIIa-inhibited diluted thromboplastin time can reflect coagulation process].

OBJECTIVE: To establish a screening test that can reflect two stages of coagulation process. METHODS: With FXII a being blocked, the effects of various dilution of thromboplastin on clotting time were observed. FX a activity was determined by chromogenic assay. RESULTS: (1) At high concentration of thromboplastin, FXII a-inhibited diluted thromboplastin time (FXII ai DTT) of pooled normal plasma and FXI deficient plasma was very similar, but at low concentration, FXII ai DTT was in order of FVIII and FIX deficient plasma > FXI deficient plasma > pooled normal plasma. (2) FXI consumption by immunologic method induced FXII ai DTT of pooled normal plasma prolonged, and addition of FXI to FXI deficient plasma shortened FXII ai DTT. (3) Alpha-thrombin blocked by hirudin at different time (10 - 80 seconds) resulted in decreased FXa generation, and the earlier the block, the more the decrease. Under the same condition, the amount of FXa generation was in order of platelet-rich plasma > platelet-poor plasma > FXI deficient plasma. CONCLUSION: (1) Our data support the two-stage hypothesis and confirm the important role of FXI in the amplification stage. (2) FXII ai DTT as a screening test for coagulation process may be practicable.

Blood Coagulation↗
PubMed2000

[Altered subcellular distribution of daunorubicin in the non-P-glycoprotein-mediated multidrug-resistant cell line HL-60/ADR].

OBJECTIVE: To investigate DNR subcellular distribution in the non-P-glycoprotein-mediated multidrug-resistant cell line HL-60/ADR and its relation to multidrug resistance. METHODS: DNR subcellular disposition was studied by confocal scanning laser microscopy, fluorescent methods, MTT and RT-PCR. The effects of verapamil, brefeldin A, chloroquine were also examined. RESULTS: In the drug-sensitive cell line HL-60 DNR fluorescence distributed evenly in the nucleus and cytoplasm, while in the resistant cell line DNR distributed in a punctate pattern in the cytoplasm and was reduced in the nucleus. Verapamil, brefeldin A, but not chloroquine could recover the intracellular distribution of DNR from punctate to even in the resistant cell line. CONCLUSION: Altered subcellular disposition of DNR in resistant cell line was involved in the mechanism of multidrug resistance.

Antibiotics, Antineoplastic↗
PubMed2000

[Effects of pulsed Nd:YAG laser irradiation on shear bond strength of composite resin bonded to porcelain].

OBJECTIVE: To evaluate the shear bond strength of composite resin bonded to pretreated porcelain surfaces by use of a pulsed Nd:YAG laser irradiation and by use of 8% hydrofluoric etching. METHODS: Surfaces of porcelain were roughened with coarse diamonds until the opaque body porcelains were exposed. The samples were divided into four groups. Samples of the first group were etched with 8% hydrofluoric acid for 3 min by following the manufacter's instructions. Samples of the 2nd, 3rd and 4th groups were separately irradiated by a pulsed Nd:YAG laser of three energy parameters of 15 Hz, 40 mJ; 0.6 W; 15 Hz, 60 mJ, 0.9 W and 15 Hz, 80 mJ, 1.2 W different respectively, each specimen was irradiated for 1 min. Then, silane coupling agent was equally placed on the treated surfaces for 3 min, the activator was used on each surface. The adhesive was applied and light-cured. The composite resin material was finally bonded to the treated porcelain surface, forming a 3 mm x 3 mm x 2 mm resin mass. Samples were then tested for shear bond strength between the treated porcelain and composite resin by using a SWD-10 electric universal testing machine with a crosshead speed of 1 mm/min until fracture. At the end of testing, the data was evaluated by using a two-way analysis of variance (ANOVA) comparing the shear bond strength. On the other hand, characteristic morphology of laser irradiated surfaces of porcelain was prepared and observed by a scanning electron microscopy. RESULTS: The shear bond strength of laser groups of 0.6 W, 0.9 W, 1.2 W and etching group was respectively 8.61, 14.07, 11.22 and 13.47 MPa. There was no significantly difference among groups of laser 0.9 W, 1.2 W and the etching group. This suggested that irradiated on surfaces of porcelain by Nd:YAG laser at the above laser energy could attain the same effectiveness as hydrofluoric acid etching. But the shear bond strength of laser 0.6 W group was significantly lower than the etching group. It suggested that shear bond strength would obviously decrease when laser energy was 0.6 W or lower than this parameter, and had no use in treatment on porcelain surfaces comparing to acid etching. SEM showed that porcelain surfaces irradiated by Nd:YAG laser exhibited rough, umbilicate, lava crater-like structure. This structure helped to produce mechanical retention between resin composite and porcelain. CONCLUSION: The pulsed Nd:YAG laser could replace etching method to pretreat the fracture porcelain surfaces for bonding with composite resin at appropriate energy parameters.

Composite Resins↗
PubMed2000

[Immunocytological localization of IAA in the parenchyma cell and vascular elements in the graft union of Cucurbita pepo/Cucurbita moschata at the early developmental stage].

Immuno-gold localization of IAA in cells of the graft union in the explant internode graft of Cucurbita pepo/Cucurbita moschata were investigated with electron microscopy. In parenchyma cells near the graft union, the gold particles were mainly accumulated in nucleus, plastid and endoplasmic reticulum, while no gold particles was detected in Golgi body, mitochondrion, cell wall and vacuoles. In the differentiating xylem element, the gold particles were labeled in secondary wall and cytoplasm. In the sieve element gold particles were found in the sieve plate, sieve pore and cytoplasm. There was a dense label of the gold particles in the companion cell. The role of IAA in the differentiation of the vascular elements was discussed.

Cucurbita↗
PubMed2000

[Study on inhibitory actions of san huang yi gan capsule (SHYGC) on HBeAg with seropharmacological method].

In this paper, the inhibitory actions of SHYGC on HBeAg in vitro were studied with the seropharmacological method. By Enzyme Linked Immuno Sorbent Assay (ELISA), it was found that the rabbit sera containing SHYGC have significant inhibitory effects on HBeAg, and they become stronger with the drug concentration in sera improved and the actions time prolonged, they decrease with the HBeAg concentration improved, and the effects of the sera containing hing-dose drugs equal those of Su Xiao Jing containing 250 micrograms/g effective chloric. The direct external inhibitory effects of SHYGC in original pharmaceutics are stronger than those of the sera containing drugs. It probably indicated that the active ingredients of SHYGC could not be digested and absorbed completely from gastrointestine, or were inactived by metabolism in vivo.

Animals↗
PubMed1999

Transforming growth factor-beta induces collagenase-3 expression by human gingival fibroblasts via p38 mitogen-activated protein kinase.

Human collagenase-3 (matrix metalloproteinase 13 (MMP-13)) is characterized by exceptionally wide substrate specificity and restricted tissue specific expression. Human skin fibroblasts in culture express MMP-13 only when they are in three-dimensional collagen (Ravanti, L., Heino, J., López-Otín, C., and Kähäri. V.-M. (1999) J. Biol. Chem. 274, 2446-2455). Here we show that MMP-13 is expressed by fibroblasts during normal human gingival wound repair. Expression of MMP-13 by human gingival fibroblasts cultured in monolayer or in collagen gel was induced by transforming growth factor-beta1 (TGF-beta1). Treatment of gingival fibroblasts with TGF-beta1 activated two distinct mitogen-activated protein kinases (MAPKs): extracellular signal-regulated kinase 1/2 (ERK1/2) in 15 min and p38 MAPK in 1 and 2 h. Induction of MMP-13 expression by TGF-beta1 was blocked by SB203580, a specific inhibitor of p38 MAPK, but not by PD98059, a selective inhibitor of ERK1/2 activation. Adenovirus-mediated expression of dominant negative p38alpha and c-Jun potently inhibited induction of MMP-13 expression in gingival fibroblasts by TGF-beta1. Infection of gingival fibroblasts with adenovirus for constitutively active MEK1 resulted in activation of ERK1/2 and JNK1 and up-regulation of collagenase-1 (MMP-1) and stromelysin-1 (MMP-3) production but did not induce MMP-13 expression. In addition, activation of p38 MAPK by constitutively active MKK6b or MKK3b was not sufficient to induce MMP-13 expression. These results show that TGF-beta-elicited induction of MMP-13 expression by gingival fibroblasts is dependent on the activity of p38 MAPK and the presence of functional AP-1 dimers. These observations demonstrate a fundamental difference in the regulation of collagenolytic capacity between gingival and dermal fibroblasts and suggest a role for MMP-13 in rapid turnover of collagenous matrix during repair of gingival wounds, which heal with minimal scarring.

Cells, Cultured↗