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Biomedical subjects

Min Zhu

Publications and source records attributed to Min Zhu.

105 records · Page 6Linked to original sources
PubMed2002

An experimental study on the expression of heme oxygenase-2 mRNA in Hirschsprung's disease.

In order to investigate the relationship between the expression of heme oxygenase-2 (HO-2) mRNA and the pathogenesis of Hirschsprung's disease (HD), total ribonucleic acid (RNA) was extracted in the aganglionic and ganglionic segments of colon respectively from 15 cases of HD. The single-stranded cDNA of HO-2 was synthesized and further amplified by reverse transcription-polymerase chain reaction (RT-PCR). The expression of HO-2 mRNA was normal in ganglionic segments, but absent in aganglionic segments. It is concluded that the absence of HO-2 mRNA expression may be an important mechanism responsible for HD.

Child↗
PubMed2002

Molecular and genetic characterizations of five pathogenic and two non-pathogenic monoclonal antiphospholipid antibodies.

Antiphospholipid syndrome (APS) is an autoimmune disease that is characterized by thrombosis, recurrent fetal loss and thrombocytopenia. Antiphospholipid antibodies, detected by enzyme-linked immunoabsorbent assays (aCL) and/or in vitro blood clotting assays (LAC) are strongly associated with APS. Both the molecular structures used by pathogenic antiphospholipid antibodies and the genetic mechanisms leading to their production are unknown. We describe here the variable region genes of seven IgG antiphospholipid antibodies derived from two APS patients. Of these, five are pathogenic as defined in a mouse model of thrombosis and two are not. Analyses of the expressed variable region genes show no preferential V gene usage. However, similar to anti-DNA antibodies, pathogenic antiphospholipid antibodies contain an increased number of arginine residues in the third complimentarity-determining region (CDR3) of their H chains. The increased accumulation of arginine residues in the V(H) CDR3 may act to enhance antigen binding, promote disease and point to the importance of the H chain in the pathogenic potential of certain antiphospholipid antibodies.

Adolescent↗
PubMed2002

The study of nafion/xanthine oxidase/au colloid chemically modified biosensor and its application in the determination of hypoxanthine in myocardial cells in vivo.

A novel hypoxanthine (Hx) microsensor was constructed. In this work, Nafion xanthine oxidase (XOD) and Au colloid were immobilized onto the surface of a Pt microelectrode. The enzyme biosensor displayed a quick and sensitive response to Hx. Under physiological conditions, a low detection limit, with high selectivity and sensitivity for Hx determination were obtained. The oxidation current [investigated using current-time (I-t) plots] was linear with Hx concentration ranging from 2.0 x 10(-7) to 2.0 x 10(-5) mol L(-1) with a calculated detection limit of 1.0 x 10(-7) mol L(-1) (S/N of 3). The biosensor should be promising for in vivo measurement of Hx without interferences and fouling. The change of Hx concentration in cardiac myocytes stimulated by L-arginine (L-Arg) and acetylcholine (Ach) was also studied.

Biosensing Techniques↗
PubMed2002

Human adipose tissue is a source of multipotent stem cells.

Much of the work conducted on adult stem cells has focused on mesenchymal stem cells (MSCs) found within the bone marrow stroma. Adipose tissue, like bone marrow, is derived from the embryonic mesenchyme and contains a stroma that is easily isolated. Preliminary studies have recently identified a putative stem cell population within the adipose stromal compartment. This cell population, termed processed lipoaspirate (PLA) cells, can be isolated from human lipoaspirates and, like MSCs, differentiate toward the osteogenic, adipogenic, myogenic, and chondrogenic lineages. To confirm whether adipose tissue contains stem cells, the PLA population and multiple clonal isolates were analyzed using several molecular and biochemical approaches. PLA cells expressed multiple CD marker antigens similar to those observed on MSCs. Mesodermal lineage induction of PLA cells and clones resulted in the expression of multiple lineage-specific genes and proteins. Furthermore, biochemical analysis also confirmed lineage-specific activity. In addition to mesodermal capacity, PLA cells and clones differentiated into putative neurogenic cells, exhibiting a neuronal-like morphology and expressing several proteins consistent with the neuronal phenotype. Finally, PLA cells exhibited unique characteristics distinct from those seen in MSCs, including differences in CD marker profile and gene expression.

Adipose Tissue↗
PubMed2002

Myogenic differentiation by human processed lipoaspirate cells.

The use of undifferentiated cells for cell-based tissue engineering and regeneration strategies represents a promising approach for skeletal muscle repair. For such strategies to succeed, a readily available source of myogenic precursor cells must be identified. We have previously shown that cells isolated from raw human lipoaspirates, called processed lipoaspirate cells, display multilineage mesodermal potential in vitro. Because human liposuctioned fat is available in large quantities and can be harvested with low morbidity, it may be an ideal source of stem cells for tissue-engineering applications. In this study, processed lipoaspirate cells were isolated from raw lipoaspirates harvested from eight patients who underwent cosmetic surgery. Processed lipoaspirate cells were placed in promyogenic conditions for up to 6 weeks, and the expression of the myogenic markers MyoD1 and myosin heavy chain was confirmed by using structure, histology, and reverse transcriptase-polymerase chain reaction. Histologic results were quantitated as an indicator or myogenic differentiation levels. We found that induced human processed lipoaspirate cells form multinucleated cells after 3 weeks of induction, indicative of the formation of myotubes. In addition, MyoD1 and skeletal muscle myosin heavy chain are expressed at distinct time points during differentiation with MyoD1 expression preceding expression of myosin. Finally, approximately 15 percent of human processed lipoaspirate cells can be induced toward myogenic differentiation 6 weeks after induction. In summary, our findings suggest that human processed lipoaspirate cells differentiate into myogenic cells. Furthermore, these cells may be a useful source for skeletal muscle engineering and repair.

Adipocytes↗
PubMed2002

Rat extramedullary adipose tissue as a source of osteochondrogenic progenitor cells.

Human liposuction aspirates contain pluripotent adipose-derived mesodermal stem cells that have previously been shown to differentiate into various mesodermal cell types, including osteoblasts and chondrocytes. To develop an autologous research model of bone and cartilage tissue engineering, the authors sought to determine whether rat inguinal fat pads contain a similar population of osteochondrogenic precursor cells. It was hypothesized that the rat inguinal fat pad contains adipose-derived multipotential cells that resemble human adipose-derived mesodermal stem cells in their osteochondrogenic capacity. To test this, the authors assessed the ability of cells isolated from the rat inguinal fat pad to differentiate into osteoblasts and chondrocytes by a variety of lineage-specific histologic stains. Rat inguinal fat pads were isolated and processed from Sprague-Dawley rats into a fibroblast-like cell population. Cell cultures were placed in pro-osteogenic media containing dexamethasone, ascorbic acid, and beta-glycerol phosphate. Osteogenic differentiation was assessed at 2, 4, and 6 weeks. Alkaline phosphatase activity and von Kossa staining were performed to assess osteoblastic differentiation and the production of a calcified extracellular matrix. Cell cultures were also placed in prochondrogenic conditions and media supplemented with transforming growth factor-beta1, insulin, transferrin, and ascorbic acid. Chondrogenic differentiation was assessed at 2, 7, and 14 days by the presence of positive Alcian blue staining and type II collagen immunohistochemistry. Cells placed in osteogenic conditions changed in structure to a more cuboidal shape, formed bone nodules, stained positively for alkaline phosphatase activity, and secreted calcified extracellular matrix by 2 weeks. Cells placed in chondrogenic conditions formed cartilaginous nodules within 48 hours that stained positively for Alcian blue and type II collagen. The authors identified the rat inguinal fat pad as a source of osteochondrogenic precursors and developed a straightforward technique to isolate osteochondrogenic precursors from a small animal source. This relatively easily obtained source of osteochondrogenic cells from the rat may be useful for study of tissue engineering strategies and the basic science of stem cell biology.

Adipose Tissue↗
PubMed2002

Expression of a novel zinc-finger cDNA, IA-1, is associated with rat AR42J cells differentiation into insulin-positive cells.

INTRODUCTION: IA-1, an insulinoma-associated cDNA-1, encodes a zinc-finger DNA-binding protein originally isolated from a human insulinoma subtraction library. AIM: To demonstrate the restriction of IA-1 gene expression in human fetal pancreata of different gestational stages and to determine whether the expression of IA-1 gene is associated with rat AR42J cell differentiation into insulin-positive cells. METHODOLOGY: To examine whether the IA-1 gene is associated with pancreatic endocrine cell differentiation, we used a rat pancreatic amphicrine cell line, AR42J, to investigate whether the expression of the IA-1 gene coincides with AR42J cells converting into either endocrine or exocrine lineage. We also examined a set of islet transcription factors that regulate key differentiation steps involved in activating the genes that confer the specialized functions of terminally differentiated pancreatic islet cells. RESULTS: When the AR42J cells were converted into insulin-positive cells induced by GLP-1, insulinoma conditioned-medium, or both, we observed a significant elevated expression of mRNA for IA-1 and islet-specific transcription factors such as Pdx-1, NeuroD/beta2, and Nkx6.1. In contrast, dramatically decreased expression of mRNA for IA-1 and islet-specific transcription factors was displayed when AR42J cells were converted into the acinar-like phenotype by dexamethasone. CONCLUSIONS: IA-1 gene was shown to be developmentally regulated in fetal pancreatic cells, and its expression pattern is consistent with parallel changes in islet-specific transcription factors during the endocrine differentiation of AR42J cells.

Adult↗
PubMed2002

Population pharmacokinetic modeling of pyrazinamide in children and adults with tuberculosis.

STUDY OBJECTIVE: To determine population pharmacokinetic parameters of pyrazinamide after multiple oral doses given to children and adults with tuberculosis. DESIGN: Prospective, multiple-dose population pharmacokinetic study. SETTING: Five hospitals in the United States. PATIENTS: Sixty-seven adults and 23 children with active tuberculosis. INTERVENTION: The 90 patients received multiple oral doses of pyrazinamide as part of their treatment, based on the best clinical judgment of the attending physicians and in keeping with standard clinical practices at each institution. The patients also received other antituberculosis drugs empirically or based on in vitro susceptibility data. MEASUREMENTS AND MAIN RESULTS: Serum samples were collected over 12 hours after dosing and were assayed with a validated gas chromatography assay with mass selective detection. Concentration-time data were analyzed by using population methods. Pyrazinamide concentrations increased linearly with increasing oral doses (185-3550 mg). Median maximum serum concentration values were 41.0 microg/ml with daily dosing and 66.1 microg/ml with larger, twice-weekly dosing. Incomplete (18%) or delayed (30%) absorption was more common in children than in adults (1% for each). Pharmacokinetic parameters of pyrazinamide were independent of human immunodeficiency virus status and patient demographics, except for body weight. Population elimination half-life values in pediatric and adult patients were 3.5 and 6.0 hours, respectively. Median volume of distribution (L/kg) was 32% larger in children, and median clearance (L/hr/kg) was 106% larger in children, with a resultant median half-life 43% shorter in children. CONCLUSION: Pyrazinamide concentrations and most pharmacokinetic parameters were comparable to those previously published. Apparent half-life was somewhat shorter than that in previous reports. Compared with adults, absorption of pyrazinamide in children appeared more likely to be incomplete or delayed.

Adult↗
PubMed2002

Targeted disruption of the protein tyrosine phosphatase-like molecule IA-2 results in alterations in glucose tolerance tests and insulin secretion.

IA-2 is a major autoantigen in type 1 diabetes. Autoantibodies to IA-2 appear years before the development of clinical disease and are being widely used as predictive markers to identify individuals at risk for developing type 1 diabetes. IA-2 is an enzymatically inactive member of the transmembrane protein tyrosine phosphatase family and is an integral component of secretory granules in neuroendocrine cells. To study its function, we generated IA-2-deficient mice. Northern and Western blot analysis showed that neither IA-2 mRNA nor protein was expressed. Physical examination of the IA-2(- /-) animals and histological examination of tissues failed to reveal any abnormalities. Nonfasting blood glucose levels, measured over 6 months, were slightly elevated in male IA-2(-/-) as compared to IA-2(+ /+) littermates, but remained within the nondiabetic range. Glucose tolerance tests, however, revealed statistically significant elevation of glucose in both male and female IA-2(-/-) mice and depressed insulin release. In vitro glucose stimulation of isolated islets showed that male and female mice carrying the disrupted gene released 48% (P < 0.001) and 42% (P < 0.01) less insulin, respectively, than mice carrying the wild-type gene. We concluded that IA-2 is involved in glucose-stimulated insulin secretion.

Animals↗
PubMed2002

[The ratio of soft and hard after bimaxillary operations in patients with skeletal class III malformations].

OBJECTIVE: To study the ratio between soft and hard tissue on the horizontal plane after the operations of maxillary Le Fort I advancement osteotomy and mandibular setback osteotomy in patient with skeletal class III malformations. It can help to predict precisely the post-operational profile. METHODS: 20 patients with skeletal class III malformation were taken cephalometric films pre-and post-operationally. The coordinate of landmarks were given from two films by computer analysis system. Different values in X axis were analysed statistically. RESULTS: All mandibular soft tissue landmarks were correlated with hard tissue landmarks (r<0.5, P>0.05). The ratios were 1:1 except the Pogonion(<1:1). Point of Sn was not correlated with the maxillary hard tissue significantly(r<0.5, P>0.05). CONCLUSION: The poor correlation between maxillary Sn and hard tissue was affected by many factors. It is easy to mark the mandible landmarks clearly. The ratio should help to predict the post-operation profile in patients with skeletal class III malformations.

English Abstract↗
PubMed2002

[Stimulation and evaluation on maxillary distraction osteogenesis using CASSOS 2001].

OBJECTIVE: To simulate maxillary distraction osteogenesis and evaluate the change of soft and hard tissue before and after treatment, using Computer-Assisted Simulation System for Orthognathic Surgery( CASSOS 2001). METHODS: A fourteen-year-old boy with severe maxillary hypoplasia, due to unilateral cleft lip and palate, was analysed by cephalometric analysis. The simulations of maxillary distraction osteogenesis (Le Fort I osteotomy and Le Fort II osteotomy) were re-analysed. After the treatment, cephalometric analysis was preformed again. The data were compared. RESULTS: The maxillary hypoplasia was well treated using maxillary distraction osteogenesis; Compared with Le fort I osteotomy, more satisfactory results can be obtained by Le fort I distraction osteogenesis. CONCLUSION: Maxillary distraction osteogenesis is a better way to treat severe maxillary hypoplasia with operated CLP than maxillary osteotomy. CASSOS 2001 can help surgeons and patients on simulation and evaluation of maxillary distraction osteogenesis, and on decision of treatment plan.

English Abstract↗
PubMed2002

[The role of dead bacteria in streptococcus sanguis biofilm reformation].

OBJECTIVE: To investigate the role of dead bacteria in Streptococcus sanguis biofilm reformation. METHODS: Vital fluorescent staining technique and Confocal laser Scanning Microscopy (CLSM) were combined to observe Streptococcus sanguis biofilm on the saliva-coated glass (SCG) in an artificial mouth model, the thickness and bacterial density were compared between biofilm reformed on saliva covered slide with dead cells (test group) and biofilm reformed on saliva coated slide without dead cells (control group) at different times. RESULTS: At 30 min, the bacterial density rather than biofilm thickness of test group was significantly higher than that of control group (P<0.05), whereas at 60 min, 120min, 240min, the biofilms were significantly thicker in test group than that (P<0.05). CONCLUSION: The dead cells may help biofilm reformation during the formation of biofilm.

English Abstract↗
PubMed2000

Identification of Novel Regulatory Elements of Human Stem Cell Factor Gene in MCF Cell.

Human stem cell factor(hSCF)is a pluripotent growth factor that regulates proliferation, differentiation and migration of certain mammalian stem cells, such as primordial germ cells etc. It is shown that hSCF and its receptor are commonly co-expressed in human breast cancer cells. Up to now, the definite regulatory mechanism of hSCF gene in breast cancer cells is unclear, except that its 5'flanking sequence contains essential elements for regulating transcription. To localize the regulatory elements responsible for the regulation of the hSCF gene, we performed transient transfection study in MCF cells, with a series of luciferase reporter gene constructs, containing different 5x end deletions of hSCF gene. This study indicates that the region of -1190 -853 significantly enhanced the luc gene expression, while the region of -339 -162 inhibited the expression. Eletrophoretic mobility shift assay confirmed that MCF nuclear extract proteins bound to both -1190 -853 and -339 -273 regions, forming specific DNA-protein complexes, indicating that there were nuclear protein binding sites in these regions. The results suggest that both -1190 -853 and -339 -273 DNA fragments of the hSCF 5'flanking sequence may be novel regulatory elements, and may play a role in the regulation of hSCF gene expression in MCF cells.

Journal Article↗