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Biomedical subjects

J Han

Publications and source records attributed to J Han.

At least 109 records · Page 6Linked to original sources
PubMed2001

[Manufacture and study of porous poly(l-lactic acid) (PLLA)/beta-tricalcium phosphate (beta-TCP) composite].

A promising alternative to supply bone substitutes is to develop living tissue substitutes based on biodegradable materials, which is called bone tissue engineering. One of the research high-lights of bone tissue engineering is to design and manufacture scaffolds for cell attaching, migrating, and proliferating. A process which consists of a solvent casting stage, a compression molding stage and a leaching stage has been used to fabricate macroporous composites of poly(l-lactic acid) (PLLA) and beta-tricalcium phosphate (beta-TCP). The effects of the weight fraction of porogen--NaCl, of the weight ratio of PLLA to beta-TCP and of the diameters of beta-TCP on the porosities, the average pore diameters and the compressive yield strength and compressive modulus have been studied. The results showed that the porosities and the average pore diameters increased and the compressive yield strength and modulus decreased when the weight fraction went from 50% to 90%. The compressive yield strength and compressive modulus could be improved by changing the weight ratio of PLLA to beta-TCP and the diameters of beta-TCP in low-porosity composites (lower than 70%). But high-porosity composites (90%) were not reinforced by changing the weight ratio.

Biocompatible Materials↗
PubMed2001

[Intratumoral injection of macroaggragated albumin and colloidal 32P for the treatment of hepatocellular carcinoma].

OBJECTIVE: To study the tumor deposition and systemic distribution of colloidal (32)P in single colloidal (32)P injection and macroaggragated albumin (MAA) injection followed by colloidal (32)P and to evaluate their clinical effects and side effects for the treatment of hepatocellular carcinoma. METHODS: H(22) hepatocellular cancer cells were inoculated subcutaneously in the right fore leg of Balb/c mice. When the tumors reached to 1.0 cm in diameter about 10 days postinjection, the mice were divided into two groups randomly. In the first group, the tumors were only injected with 1.85 MBq of colloidal (32)P; while in the second group, with 1 +/- 10(5) particles of MAA followed by 1.85 MBq of colloidal (32)P. The radioactivity in the tumor, blood, heart, liver, kidney, spleen, and bone of each animal was determined at 30min, 24 h, 48 h, 8 d, and 16 d postinjection. Histopathology of tumors was observed at 16 d and 1 month postinjection. The ultrasound-guided intratumoral injection of MAA and colloidal (32)P was performed on 30 patients with hepatocellular cancer. The evaluation of efficacy and side effects was made on the basis of clinical manifestations, histopathological changes, variations in tumor size, serum AFP, the functions of heart, liver, kidney, blood routine, and immune functions before and after the treatment. RESULTS: Intratumoral injection of colloidal (32)P resulted in necrosis and fibrosis of the tumor cells. Pretreatment with MAA before administration of colloidal (32)P effectively decreased the diffusion of colloidal (32)P from the tumor to blood, and led to retention of colloidal (32)P in the tumor for a longer time. After treatment, a significant shrinkage of the tumor size was seen in all cases with the average shrinkage rate of 53.25%. Serum AFP values decreased remarkably. Clinical symptoms alleviated. The survival rate of 1, 2, and 3 years was 90%, 76.67%, 43.33%. No side effect was found. CONCLUSIONS: Intratumoral injection of MAA and colloidal (32)P is a simple, safe, and effective alternative for the treatment of hepatocellular cancer.

Adult↗
PubMed2001

Cellular responses to tumor necrosis factor.

TNF is a proinflammatory cytokine that plays an important role in many physiological and pathological conditions through the regulation of immunological reactions. Many of TNF functions have been proven to be cell type-specific, and the specificity of TNF-induced cellular responses in a given cell is determined by the specific intracellular signaling pathways that are activated by TNF. Although current information is insufficient to sort out how the cell type specificity is controlled by the different intracellular signaling pathways, a number of signaling pathways that are commonly activated in many types of cells by TNF have been revealed. This review weighs the current knowledge of these TNF-induced signaling pathways.

Animals↗
PubMed2001

[The prevalence of beta-thalassemia heterozygotes compound alpha-thalassemia in Guangdong district].

OBJECTIVE: To investigate the prevalence of beta-thalassemia (beta-thal) heterozygotes compound alpha-thal in Guangdong area. METHODS: alpha-thal 1 genes were amplified in 500 beta-thal carriers diagnosed by reverse dot blotting (RDB) using gap-PCR method, alpha-thal 2 genes were detected in 400 of the 500 beta-thal carriers using Southern blotting with alpha-globin DNA probe and restrict endonuclease zymogram analytical method. RESULTS: Forty three alpha-thal-1(alpha alpha/- -SEA) cases were identified in the 500 beta-thal traits, and 26 alpha-thal 2 including 17 rightward deletion (alpha alpha/- alpha 3.7) and 9 leftward deletion(alpha alpha/-alpha 4.2) cases were identified in the 400 beta-thal traits. CONCLUSION: The prevalence of beta-thal heterozygote carrying alpha-thal-1 gene was 8.6% and that of beta-thal heterozygote carrying alpha-thal-2 gene was 6.5% (4.2% rightward deletion and 2.2% leftward deletion).

Adult↗
PubMed2001

[Clinical and pathological analysis on 106 cases with uterine sarcoma].

OBJECTIVE: To analyze the clinical features and factors affecting the prognosis of uterine sarcoma with different histological types. METHODS: One hundred and six cases with uterine sarcoma treated were analyzed retrospectively, among which there were 67 cases with leiomyosarcoma (63.2%), 23 with malignant endometrial interstitial sarcomas (21.7%), 16 with malignant Mullerian mixed tumor (15.1%). According to Union Internationale Contre le Cancer (UICC) staging, 70 cases were on stage I, 12 cases were on stage II, 19 cases belonged to stage III, and 5 cases belonged to stage IV. RESULTS: (1) The patients with leiomyosarcoma and endometrial interstitial sarcoma were relatively younger, the patients of them aged under 50 amounted to 70.1% (47/67) and 60.9% (14/23) respectively, and those aged under 40 amounted to 29.9% (20/67) and 39.1% (9/23) respectively. The patients usually manifested with abnormal vaginal bleeding (67.0%), palpable mass of lower abdomen (32.1%), vaginal discharge (27.4%), pain on lower abdomen (28.4%), symptoms of oppression (25.5%), and discomfort feeling (28.3%). (2) The rate of preoperative diagnosis was 65.9%, especially that of leiomyosarcoma was lowest (42.9%). (3) In treatment, 16.0% of patients was treated by hysterectomy; bilateral salpingo-oophorectomy and pelvic lymphadenectomy; 75.5% of them by hysterectomy and bilateral salpingo-oophorectomy; after operation, 74.5% of them were treated by chemotherapy, 11.3% by radiotherapy, 6.6% by additional progesterone. (4) The survival period of the patients was related to pathologic types and clinical stages and ages of the patients. The prognosis of the patients with leiomyosarcoma younger earlier stage was better. CONCLUSIONS: The clinical symptom of uterine sarcoma is nonspecific (mostly abnormal vaginal bleeding) and the prognosis is poor. The patients with leiomyosarcoma are younger and have better prognosis, but the rate of preoperative diagnosis is low. The prognosis of uterine sarcoma is related to pathologic types, clinical stage and ages of the patients.

Adult↗
PubMed2001

[Effects of air staging with absorbents on trace metal during coal combustion].

Staged combustion was carried out on laboratory-scale pulverized coal combustion with different absorbents. The experiment indicated staged combustion increased emission of submicron particles, which went against the control of trace elements, especially for those of high volatile elements, such as Cu, Ni. The thermodynamics calculation also indicate the transformation of trace metal was different with different atmosphere, suboxidized and reduced species were more easily formed under reduced condition. In both conditions, absorbents show a certain absorptive ability to trace metal, and different absorbent had different ability. For unstaged combustion, kaolinite was the best for Co, Cr and Ni; dolomite for Be, and CaO for Cu. But for under staged condition, HZ- dolomite was the best for Be, Cr and Ni; Kaolinite for Co and Cu.

Absorption↗
PubMed2001

Primary culture of porcine pancreatic acinar cells.

OBJECTIVE: To develop a method for the primary culture of porcine pancreatic acinar cells. INTERVENTIONS: Dispersed pancreatic acinar cells available utilizing RPMI-1640 medium containing collagenase III. After purification, the isolated acinar cells were cultured in RPMI-1640 medium with the addition of 2.5% fetal bovine serum. MAIN OUTCOME MEASURES: The morphological characteristics of acinar cells were described. (3)H-thymidine incorporation of acinar cells and the activity of amylase or lipase were determined during the culture process. RESULTS: There were no remarkable morphological changes in the pancreatic acinar cells during the 20 days culture. The acini showed a tendency to gather but did not attach to the walls of the culture disks. A good (3)H-thymidine incorporation of acinar cells in the primary culture was maintained. The secretion of amylase or lipase from the acini decreased with the length of time of the culture. DISCUSSION: The primary culture of acinar cells from a porcine pancreas which was carried out in this study maintained the normal morphology of the acinar cells and their ability to grow but not their secretion of amylase or lipase. The method would benefit by the further experiments on acini of porcine pancreas.

Animals↗
PubMed2001

[Effects of selective RAR or/and RXR retinoids on the proliferation and differentiation of NB4 cells and their mechanisms].

OBJECTIVE: To investigate the effects of RARbeta selective agonist and RARalpha antagonist (RARbeta +/RARalpha -) BMS453 in combination with RXR selective agonist (RXR+) BMS649 on the proliferation and differentiation of NB4 cells, and illustrate the mechanism. METHODS: The proliferation and differentiation of NB4 cells were detected by cell count, morphological observation, NBT reduction assay, immunofluorescence analysis, flow cytometry and RT-PCR. RESULTS: BMS453 in combination with BMS649 could significantly inhibited the growth of NB4 cell in the manner of dose and time dependence. NB4 cells treated with BMS453 and BMS649 were irreversibly committed to morphologically and functionally more differentiated granulocytic cells. When NB4 cells were treated with BMS453 and BMS649 for 0, 1, 3, 12, 24 and 48 h, RARalpha, RARbeta and RXRalpha expressions were up regulated at 1 h and 3h, respectively. As compared to ATRA, the situations had no significant difference. In contrast, BMS453 or BMS649 alone was ineffective on NB4 cells. CONCLUSION: BMS453 (RARbeta+/RARalpha-) in combination with BMS649 (RXR+) significantly and synergistically inhibit proliferation of NB4 cells and induce them into granulocytic differentiation, the mechanism of which may be mediated by the AF-2 activity of RXR.

Cell Differentiation↗
PubMed2001

[Study of specific targeting cytotoxicity mediated by anti-CD(3)/anti-CD(20) Diabody].

OBJECTIVE: To study the specific targeting cytotoxicity mediated by an anti-CD(3)/anti-CD(20) diabody. METHODS: The diabody was purified by affinity chromatography and identified by Western blot assay, size exclusion chromatography, FACS and rosetting assay; the effect of the anti-CD(3)/anti-CD(20) diabody mediated lysis of CD(20)-expressing tumor cells was assayed by (51)Cr release assay in vitro and by human B cell tumor nude mice xenograft model in vivo. RESULTS: The anti-CD(3)/anti-CD(20) diabody could bind both Jurkat cells (CD(3)(+)) and Daudi cells (CD(20)(+)) and appeared to be potent in targeting activated peripheral blood mononuclear cell (PBMC) to lyse Daudi cells in vitro. Furthermore, it inhibited tumor growth and prolonged the survival of mice bearing xenografted Raji cells. CONCLUSION: The diabody proved to be a potent agent for targeting peripheral blood lymphocytes to lyse CD(20) antigen expressing tumor cells in vitro and in vivo.

Animals↗
PubMed2001

[Percutaneous testicular sperm aspiration and intracytoplasmic sperm injection in the treatment of severe male infertility].

OBJECTIVE: To investigate the efficacy of intracytoplasmic sperm injection (ICSI) combined with percutaneous testicular sperm aspiration (PTSA) in the treatment of severe male infertility. METHODS: From October 1998 to December 2000, 162 couples were enrolled, and ICSI and PTSA were adopted. Ovarian stimulation was achieved by the short protocol. All metaphase II (M II) oocytes were selected for ICSI. RESULTS: 1,517 M II oocytes were injected in 185 cycles, 990 fertilized (65.3%), and 152 embryo implanted. 54 couples achieved clinical pregnancy (35.5%). CONCLUSION: PTSA combined with ICSI is a rapid, convenient, painless and effective approach for the treatment of severe male infertility.

Adult↗
PubMed2001

[Effects of IL-8 on neutrophils under fluid shear].

OBJECTIVE: In order to elucidate the effect of IL-8 on neutrophils in a systematic and all-round way, we introduced an important physiological environment of neutrophils, fluid flow, into this study on the changes in some responses of neutrophils to IL-8 and the inter relationship of those responses under the conditions of different patterns of flow field. METHODS: After using IL-8 and steady flow or sinusoidal-oscillate fluid shear rate simultaneously acting on separated neutrophils for one minute, we measured the expression of CD18, CD62L and the F-actin content with flow cytometry and measured the free calcium concentration inside cells ([Ca2+]i) with the fluorescent stain Fura2/AM using the fluorescent spectrophotometer. RESULTS: It was found that flow shear stress could influence the expression of surface adherence molecule of neutrophils under the action of IL-8. CD18 surface expression increased, and CD62L shed under different flow shear rates, but no significant relationship of these changes with the intensity and pattern of shear stress was noted. On the other hand, the F-actin content in neutrophils under the action of shear stress and IL-8 decreased significantly at low shear rate and then gradually increased at high shear rate (600s -1) to the control value (without shear). The [Ca2+]i concentration under the action of shear stress and IL-8 decreased significantly at low shear rate followed by a quick increase at high shear rate. CONCLUSION: The flow shear stress can influence the activation effects of IL-8 on neutrophils and regulate the magnitude of neutrophil reactions to a great extent, and among these reactions, the change of [Ca2+]i concentration is the most sensitive one and the greatest one. This is in consistence with its second messenger role in the signal transduction pathway. Our results could serve as a basis on which to understand better the mechanism of inflammatory reaction wherein the neutrophils under flow condition of blood are involved.

Actins↗
PubMed2001

[High performance liquid chromatography/electrospray ionization mass spectrometric characterization of recombinant L-asparaginase II].

AIM: To characterize the primary structure of recombinant L-asparaginase II product. METHODS: The molecular weight of the protein was measured by pneumatically-assisted electrospray ionization mass spectrometry with flow injection mode. Subsequently, tryptic peptide mapping was performed by high performance liquid chromatography on a C8 column with tandem UV and MS detection. An easy-to-use and simple denaturation process with trichloroacetic acid was conducted prior to tryptic digest so as to release the digest resistance from the protein structure. The amino acid sequences of the tryptic peptides were elucidated based on their in-source collision-induced dissociation spectra. RESULTS: The measured molecular mass was different from the theoretical value. Three amino acid variations were unambiguously detected along the peptide backbone derived from the gene-encoding sequence. CONCLUSION: This paper revealed that LC/ESI/MS had provided a promising and robust technique in primary structure analysis and quality control of DNA-derived recombinant protein pharmaceuticals.

Amino Acid Sequence↗
PubMed2001

[Growth and osteogenesis characteristics of cultured rat marrow stromal cells under bone induction condition].

OBJECTIVE: To investigate the growth and osteogenesis characteristics of cultured rat marrow stromal cells(rMSCs) under bone induction condition. METHODS: rMSCs were isolated from adult rat using density gradient separation method. The rMSCs attachment formed soon after seeding and grew into colonies with the appearance of fibroblastic cells. The osteogenic induction compound of Dex(10(-8) mol/L), beta-GP(10 mmol/L) and AA(50 micrograms/ml) was added to different passaged rMSCs and the proliferation and osteogenic differentiation of them was observed. RESULTS: The induction compound had strong effect on promoting proliferation, especially on that of further passaged rMSCs, and its stimulation effect on osteogenesis was also well proved with the expression of alkaline phosphatase (ALP) rising after one-week induction. Further subculturing from P1 to P6 led to the increase of proliferation activity of rMSCs. After three-week induction, mineral deposits appeared in the culture. CONCLUSION: The lower expression of ALP in P1 rMSCs and the increase of it in further passages or under induction condition suggest the rMSCs in our culture system are mainly undifferentiated osteoprogenitors.

Alkaline Phosphatase↗
PubMed2000

The p38 pathway provides negative feedback for Ras proliferative signaling.

Ras activates three mitogen-activated protein kinases (MAPKs) including ERK, JNK, and p38. Whereas the essential roles of ERK and JNK in Ras signaling has been established, the contribution of p38 remains unclear. Here we demonstrate that the p38 pathway functions as a negative regulator of Ras proliferative signaling via a feedback mechanism. Oncogenic Ras activated p38 and two p38-activated protein kinases, MAPK-activated protein kinase 2 (MK2) and p38-related/activated protein kinase (PRAK). MK2 and PRAK in turn suppressed Ras-induced gene expression and cell proliferation, whereas two mutant PRAKs, unresponsive to Ras, had little effect. Moreover, the constitutive p38 activator MKK6 also suppressed Ras activity in a p38-dependent manner whereas arsenite, a potent chemical inducer of p38, inhibited proliferation only in a tumor cell line that required Ras activity. MEK was required for Ras stimulation of the p38 pathway. The p38 pathway inhibited Ras activity by blocking activation of JNK, without effect upon ERK, as evidenced by the fact that PRAK-mediated suppression of Ras-induced cell proliferation was reversed by coexpression of JNKK2 or JNK1. These studies thus establish a negative feedback mechanism by which Ras proliferative activity is regulated via signaling integrations of MAPK pathways.

3T3 Cells↗
PubMed2000

Induction of prostaglandin endoperoxide synthase 2 by mitogen-activated protein kinase cascades.

Prostaglandin endoperoxide synthase (PGHS) catalyses the rate-limiting step in the formation of prostaglandin and thromboxane eicosanoids from arachidonic acid released by phospholipase A(2). Two forms of PGHS exist, PGHS-1 and PGHS-2. PGHS-2, normally absent from cells, is rapidly expressed in response to a wide variety of stimuli and has been implicated in the pathogenesis of colon cancer and several inflammatory diseases. The three principal mitogen-activated protein kinase (MAPK) pathways are the extracellular signal-regulated protein kinase (ERK), the c-Jun N-terminal kinase (JNK) cascade and the p38-MAPK cascade. The present study was undertaken to investigate the putative involvement of the MAPK cascades in PGHS-2 induction. The potential role of ERK in PGHS-2 up-regulation was assessed by using cell lines expressing, both stably and after adenoviral infection, constitutively active forms of its upstream activator MAPK/ERK kinase (MEK1). The possible involvement of JNK and p38-MAPK in positively modulating PGHS-2 transcription was investigated by using adenovirus-mediated transfer of active forms of their respective specific upstream kinases, mitogen-activated protein kinase kinase (MKK) 7 and MKK3/MKK6. ERK activation promoted the induction of PGHS-2 mRNA and protein. Similarly, activation of JNK by Ad-MKK7D and p38-MAPK by Ad-MKK3bE/Ad-MKK6bE resulted in the increased expression of PGHS-2. These results provide evidence that activation of all three of the major mammalian MAPK leads to the induction of PGHS-2 mRNA and protein. Because PGHS-2 is up-regulated by a diverse range of stimuli, both mitogenic and stress-evoking, these results provide evidence that the convergence point of these stimuli could be the activation of one or more MAPK cascade(s).

3T3 Cells↗
PubMed2000

Human glioma cell BT325 expresses a proteinase that converts human plasminogen to kringle 1-5-containing fragments.

Angiostatin, a specific angiogenesis inhibitor, is an internal fragment of plasminogen, and can be generated in many systems mediated by different enzymes in vitro. The mechanism of angiostatin generation in vivo has not been well defined. Here we demonstrated that human glioma cell line BT325 can express an enzyme that can convert purified plasminogen to angiostatin-like fragments with molecular masses of 65, 60, and 58 kDa, respectively. These fragments have an identical N-terminal as KVYLS, which starts from Lys(98) of the plasminogen precusor. According to their molecular mass, the three fragments should comprise kringle domain 1 to kringle domain 5 (kringle 1-5). The proteolytic fragments obtained as above can inhibit the growth of bovine aortic endothelial (BAE) cells specifically. The proteolysis process can be completely inhibited by serine proteinase inhibitors, and partially inhibited by EDTA. The molecular weight of the peptide, which contains an enzymatic activity responsible for the proteolysis, was 13 kD determined by gel filtration and SDS-PAGE. The present data suggest that glioma cell BT325 can produce a novel proteinase to generate kringle 1-5 of plasminogen as an angiogenesis inhibitor.

Amino Acid Sequence↗
PubMed2000

Activation of extracellular signal-regulated kinase 1/2 inhibits type I collagen expression by human skin fibroblasts.

Treatment with the lipid second messenger, ceramide, activates extracellular signal-regulated kinase-1/2 (ERK1/2), c-Jun N-terminal kinase, and p38 in human skin fibroblasts and induces their collagenase-1 expression (Reunanen, N., Westermarck, J., Häkkinen, L., Holmström, T. H., Elo, I., Eriksson, J. E., and Kähäri, V.-M. (1998) J. Biol. Chem. 273, 5137-5145). Here we show that C(2)-ceramide inhibits expression of type I and III collagen mRNAs in dermal fibroblasts, suppresses proalpha2(I) collagen promoter activity, and reduces stability of type I collagen mRNAs. The down-regulatory effect of C(2)-ceramide on type I collagen mRNA levels was abrogated by protein kinase C inhibitors H7, staurosporine, and Ro-31-8220 and potently inhibited by a combination of MEK1,2 inhibitor PD98059 and p38 inhibitor SB203580. Activation of ERK1/2 by adenovirus-mediated expression of constitutively active MEK1 resulted in marked down-regulation of type I collagen mRNA levels and production in fibroblasts, whereas activation of p38 by constitutively active MAPK kinase-3b and MAPK kinase-6b slightly up-regulated type I collagen expression. These results identify the ERK1/2 signaling cascade as a potent negative regulatory pathway with respect to type I collagen expression in fibroblasts, suggesting that it mediates inhibition of collagen production in response to mitogenic stimulation and transformation.

3T3 Cells↗