PubMed Health⌕ Search

Biomedical subjects

S F Zhang

Publications and source records attributed to S F Zhang.

At least 19 recordsLinked to original sources
PubMed2001

Report of the consensus conference on diagnostic criteria of ALI/ARDS at high altitudes in Western China.

China is a mountainous country. The Qing-Zang plateau, Yun-Gui plateau, and Yellow Land plateau, which are known as the world's ridge, are located in the west of China. The highland area over 3,000 m in height occupies one-sixth of the land area of China and half the highland area of the world. About 60-80 million people live in the regions where the elevation ranges from 1,500 m to 4,000 m. In the latter half of the last century, the influence of complex environmental factors on the human body, such as low oxygen pressure, cold climate, strong radiation, high wind speed, and super-evaporation, were studied in an extensive and profound way and formed an important field of altitude medicine. For a long time, many researchers have carried out investigations related to the systemic inflammatory response syndrome (SIRS), acute respiratory distress syndrome (ARDS), and multiple organ dysfunction syndrome (MODS) and its pathophysiological mechanism initiated by cytokines and mediators, regarding which many problems are still unclear. However, systematic research into the mechanism from SIRS to ARDS to MODS in the highlands remains blank. The diagnostic criteria of ALI/ARDS in the highlands are quite different from that in the plain, and thus was a central topic for discussion at this meeting.

Adaptation, Physiological↗
PubMed2001

Chemical treatment of an anionic surfactant wastewater: Electrospray-MS studies of intermediates and effect on aerobic biodegradability.

The effect of wet air oxidation on the aerobic biodegradability of a model wastewater containing 1000 mg L(-1) of linear alkylbenzene sulfonate (LAS) has been investigated. Semibatch oxidation experiments were performed temperature of 473 K, oxygen partial pressure of 1.3 MPa and residence times varying from 40 to 390 min, while continuous oxidation experiments were performed at a residence time of 120 min. Oxygen uptake tests were performed to assess the aerobic biodegradability of both the oxidised and the original LAS solutions using cultures that had been adapted to both LAS and oxidation intermediates. The concentration of total organic carbon, chemical oxygen demand and active detergent were followed throughout the wet oxidation and biodegradation experiments, while the main intermediates formed during wet oxidation were identified by means of Electrospray-MS and high performance liquid chromatography. It was found that LAS could be easily oxidised at 473 K to yield a group of molecules with short alkyl chains which do not behave as active detergents. Sulfonated aromatics are produced as intermediates which have had the alkyl chains shortened. The segments of alkyl chains broken off the intermediate compounds appear primarily as short chain organic acids. The original unoxidised 1000 mg L(-1) LAS solution was found to be readily biodegradable in the laboratory aerobic reactors operating at low organic loadings and substrate to microorganism concentration ratios. However, wet oxidation resulted in effluents that were less readily biodegradable than the original LAS with biodegradability decreasing with increasing degree of oxidation. These results suggest that, at the conditions under consideration, a combined chemical pre-oxidations and biological post-treatment process may be less effective in removing LAS than a single-stage biological or chemical process.

Aerobiosis↗
PubMed2000

Glucose sensor with improved haemocompatibilty.

A new biocompatible copolymer has been synthesised and used in an electrochemical enzyme-based glucose sensor. The copolymer incorporates three segments including a monomer with an electrically neutral phosphorylcholine head group that is able to reject protein adsorption and two segments that increase the affinity to polyurethane substrate. Peel and solution circulation tests showed that this material has high attachment to polyurethane. With the new copolymer as the outermost layer and the polyurethane as the diffusion-limiting membrane, the sensor showed extended linearity up to 50 mM glucose and stable output in bovine serum for 70 h. During in vivo tests, the sensor exhibited a steady current signal and a rapid transient response when the glucose concentration was raised. These results imply that the haemocompatibility of the glucose sensor coated with the new copolymer has been improved, which is crucial for a sensor used for clinical real-time monitoring. The material may also be suitable for application to other implantable devices.

Animals↗
PubMed2000

Pilocytic astrocytomas do not show most of the genetic changes commonly seen in diffuse astrocytomas.

AIMS: While it is well known that pilocytic astrocytomas are clinically distinct from diffuse astrocytomas, few comprehensive studies have focused on their genetic differences. The aim of this study was to examine pilocytic astrocytomas for genetic alterations that are commonly seen in diffuse astrocytomas. METHODS AND RESULTS: By using molecular genetic and immunohistochemical techniques, we evaluated p16, p53, CDK4 and PTEN genes in 29 pilocytic astrocytomas. Mutation screening of p53 and PTEN was performed by single strand conformation polymorphism analysis followed by direct sequencing. Loss of heterozygosity (LOH) of p53, p16 and 10q23-25 loci was performed with microsatellite markers and genomic microsatellite instability (MSI) was also screened. Protein expression of p16, p53, CDK4 and PTEN was examined by immunohistochemistry. Five tumours were found to have single genetic alterations, which included a p53 mutation, a PTEN mutation, MSI at a single microsatellite marker of the p16 locus, and one single LOH at each p16 and 10q23 loci. Protein expressions of p16, CDK4 and PTEN were detected in 73%, 61% and 38% of tumours, respectively. Significantly and in sharp contrast to diffuse astrocytomas, no pilocytic astrocytoma in our series stained for p53 protein. CONCLUSION: Pilocytic astrocytomas have neither MSI phenotype nor recurrent alterations of the p53 and p116 genes. However, altered expression of PTEN may be important in the genesis of pilocytic astrocytomas. We conclude that pilocytic astrocytomas are genetically distinct from diffuse astrocytomas. Lack of p53 mutation/immunostaining may serve as a diagnostic adjunct for differentiating pilocytic astrocytomas from diffuse astrocytomas in small neurosurgical biopsies.

Adolescent↗
PubMed1999

Genetic alterations in pediatric high-grade astrocytomas.

High-grade astrocytomas are tumors that are uncommon in children. Relatively few studies have been performed on their molecular properties and so it is not certain whether they follow different genetic pathways from those described in adult diffuse astrocytomas. In this study, we evaluated 24 pediatric high-grade astrocytomas (11 anaplastic astrocytomas and 13 glioblastomas) all of which were sporadic and primary. We studied mutations of p53, phosphatase and tensin homolog (PTEN), loss of heterozygosity (LOH) of chromosomes 17p13, 9p21 and 10q23-25, amplification of epidermal growth factor receptor (EGFR), and overexpression of EGFR and p53 protein. In addition, we searched for microsatellite instability (MSI) by using MSI sensitive and specific microsatellite markers. p53 mutations were found in 38% (9/24) of the high-grade astrocytomas and all brain stem tumors except 2 (71%, 5/7) had p53 mutations. PTEN mutations were found in 8% (2/24) of high-grade astrocytomas. However, no EGFR amplification was found in any of them. LOH was found at 17p13.1 in 50% (3/6 informative tumors), 9p21 in 83% (5/6 informative tumors), and 10q23-25 in 78% (7/9 informative tumors). Four tumors showed MSI, and 2 of them that showed widespread MSI were regarded as tumors with replication error (RER+) phenotype. All 4 tumors with MSI showed concurrent LOH of 9p21 and 10q23-25. Combining gene alterations, LOH, MSI, and gene mutations, inactivation of both alleles of PTEN and p53 was found in 57% (4/7 informative tumors) and 50% (3/6 informative tumors) of the cases respectively. We conclude that development of pediatric high-grade astrocytomas may follow pathways different from the primary or secondary paradigm of adult glioblastomas. In a subset of these tumors, genomic instability was also implicated.

Adolescent↗
PubMed1999

Molecular analysis of microdissected de novo glioblastomas and paired astrocytic tumors.

Glioblastoma multiforme (GBM) often displays morphological heterogeneity in that low-grade (LG) area with well-differentiated cells are commonly found adjacent to high-grade (HG) area with poorly-differentiated cells. This heterogeneity may cause difficulty in obtaining representative tumor samples. Nevertheless, the genetic composition of these cells has only been occasionally examined. In the present study, we examined 29 de novo glioblastomas in which distinct LG and HG areas of sufficient volumes could be identified. These areas were microdissected from paraffin-embedded tissues and analyzed for genetic alterations: p53 mutations and immunohistochemistry; allelic losses at 17p13.1, 9p21, and 10q23-25; and amplification of the epidermal growth factor receptor (EGFR) gene and immunohistochemistry. We also examined 14 paired astrocytic tumors, in which a primary Grade II astrocytoma progressed over a period of time to a Grade III or Grade IV tumor. Our findings showed that the LG areas of the de novo glioblastomas exhibited numerous genetic aberrations, the proportion of which was increased in the HG areas. Genetic abnormalities seen in the LG areas were conserved in the HG areas suggesting that these morphologically different cellular subsets were derived from a common transformed clone. Also, the LG areas were genetically different from Grade II astrocytomas of the paired tumor group, in spite of their morphological similarity. In particular, the LG areas had more deletions on 10q23-25 (75% vs 20%, p = 0.04), but fewer p53 mutations (24% vs 71%, p = 0.003) and less p53 protein labeling (45% vs 79%, p = 0.04). These differences suggest that LG and HG areas in de novo glioblastoma are genetically closer to each other compared with paired low- and high-grade tumors that have progressed over time. Moreover, only a small proportion (17%) of our de novo glioblastomas exhibited EGFR amplification while a high proportion (62%) showed either p53 mutations or allelic loss of 17p13.1. We speculate that some de novo GBMs with copious LG areas may constitute a separate group with rapid progression from Grade II astrocytomas.

Adult↗
PubMed1998

Regulation of insulin-like growth factors I and II and their binding proteins in human bone marrow stromal cells by dexamethasone.

Glucocorticoids inhibit the proliferation, but induce the differentiation, of bone marrow stromal cells into osteoblast-like cells. The mechanisms, however, are still conjectural. Since insulin-like growth factors (IGFs) have profound effects on osteoblast growth and differentiation, it is possible that glucocorticoids exert their effects on bone marrow stromal cells in part via regulation of IGFs. Therefore, we analyzed the effects of dexamethasone (Dex) on the expression of IGF I and IGF II in cultured preosteoblastic normal human bone marrow stromal cells (HBMSC). Whereas Dex decreased the concentration of IGF I in the conditioned medium since early in the treatment, the concentration of IGF II was increased progressively as culture period lengthened. As the activities of IGF I and IGF II are regulated by the IGF binding proteins (IGFBPs), we analyzed the effects of Dex on the expression of IGFBPs. Dex increased IGFBP-2 in a time-dependent manner. The increase in IGFBP-2, however, was only to the same extent as that of IGF II at most, depending on the length of treatment. Therefore, the increase in IGFBP-2 would dampen, but not eliminate, the increased IGF II activities. By contrast, Dex decreased IGFBP-3 levels, the latter increasing the bioavailability of IGF II. Although IGFBP-4 mRNA levels were stimulated by Dex, IGFBP-4 concentration in the conditioned medium was unchanged as measured by RIA. IGFBP-5 and IGFBP-6 mRNA levels were decreased by Dex in a time-dependent fashion. IGFBP-5 protein level was also decreased 1-4 days after Dex treatment. IGFBP-1 mRNA was not detectable in HBMSC. These accumulated data indicate that Dex regulates IGF I and IGF II and their binding proteins differentially in normal human bone marrow stromal cells. The progressive increase in IGF II may contribute to Dex-induced cell differentiation.

Blotting, Northern↗
PubMed1998

Human osteoblasts express a repertoire of cadherins, which are critical for BMP-2-induced osteogenic differentiation.

Direct cell-cell interactions are fundamental for tissue development and differentiation. We have studied the expression and function of cadherins in human osteoblasts during in vitro differentiation. Using reverse transcription-polymerase chain reaction and mRNA hybridization, we found that human trabecular bone osteoblasts (HOBs), osteoprogenitor marrow stromal cells (BMCs), and the osteogenic sarcoma lines, SaOS-2 and MG-63, expressed mRNA for cadherin-11 (C11) and N-cadherin (N-cad). HOBs and BMCs also expressed low levels of cadherin-4 (C4) mRNA. C11 was the most abundant cadherin protein present in human osteoblasts, and its expression was unaffected by bone morphogenetic protein-2 (BMP-2) treatment of either BMCs or HOBs. Likewise, N-cad mRNA did not change during BMP-2 incubation. Conversely, C4 protein, undetectable in transformed cell lines, was down-regulated by BMP-2 treatment of normal cells. Both C11 and C4 were localized to sites of cell-cell contact in both HOBs and BMCs, colocalized with beta-catenin, and bands corresponding to cadherins were coimmunoprecipitated by a beta-catenin antibody, findings indicative of functional cadherins. A decapeptide containing the HAV motif of human N-cad partially inhibited Ca2+-dependent cell-cell adhesion and completely prevented BMP-2-induced stimulation of alkaline phosphatase activity by BMCs. Thus, human osteoblasts and their progenitor cells express a repertoire of multiple cadherins. Cadherin-mediated cell-to-cell adhesion is critical for normal human osteoblast differentiation.

Bone Morphogenetic Protein 2↗
PubMed1997

The role of cytoskeletal elements in the two-phase denucleation process of mammalian erythroblasts in vitro observed by laser confocal scanning microscope.

The cytoskeletal elements in the denucleation processes were observed using immunofluorescence and laser confocal scanning microscopy in the Friend virus (FVA) infected splenic erythroblasts of BALB/c mice. When cultured in the presence of erythropoietin (EPO), it was shown that the synchronized erythroid precursor cells proceeded to an autonomous nuclear extrusion when the three types of cytoskeletal elements were observed contributing to different phases of that process. The vimentin intermediate filament (IF) was shown as the nuclear anchorage elements with binding sites anchored from the nuclear lamina to the center as well as to the plasma membrane periphery. A dense perinuclear layer of vimentin fluorescence in erythroblasts was observable during the periods of 12, 24 and 36 hrs. in vitro culture. The amount of vimentin IF per cell was higher than that of tubulin and F-actin at 12-24 hrs. culture, but the vimentin filaments were observed to brake down and decreased steadily when the cells became differentiated into late erythroblasts at 36-48 hrs. Such an attenuation of vimentin filaments may facilitate the eccentric movement of the nucleus which can be regarded as the initial step (phase) of denucleation. The fluorescent intensity of tubulin and actin exhibited a significant rise and aggregated between the extruding nucleus and the incipient reticulocyte prior to and during the processes of denucleation, what indicated that the actin filaments and microtubules may play roles in the second phase of the denucleation process, or final commitment of enucleation. The erythroid differentiation-denucleation factor (EDDF), as an intrinsic factor, involved in the denucleation events, was also discussed.

Animals↗
PubMed1996

Expression of bone matrix proteins during dexamethasone-induced mineralization of human bone marrow stromal cells.

Glucocorticoids have been shown to induce the differentiation of bone marrow stromal osteoprogenitor cells into osteoblasts and the mineralization of the matrix. Since the expression of bone matrix proteins is closely related to the differentiation status of osteoblasts and because matrix proteins may play important roles in the mineralization process, we investigated the effects of dexamethasone (Dex) on the expression of bone matrix proteins in cultured normal human bone marrow stromal cells (HBMSC). Treatment of HBMSC with Dex for 23 days resulted in a significant increase in alkaline phosphatase activity with maximum values attained on day 20 at which time the cell matrix was mineralized. Northern blot analysis revealed an increase in the steady-state mRNA level of alkaline phosphatase over 4 weeks of Dex exposure period. The observed increase in the alkaline phosphatase mRNA was effective at a Dex concentration as low as 10(-10) M with maximum values achieved at 10(-8)M. In contrast, Dex decreased the steady-state mRNA levels of both bone sialoprotein (BSP) and osteopontin (OPN) over a 4 week observation period when compared to the corresponding control values. The relative BSP and OPN mRNA levels among the Dex treated cultures, however, showed a steady increase after more than 1 week exposure. The expression of osteocalcin mRNA which was decreased after 1 day Dex exposure was undetectable 4 days later. Neither control nor Dex-treated HBMSC secreted osteocalcin into the conditioned media in the absence of 1 ,25(OH)(2)D(3) during a 25-day observation period. The accumulated data indicate that Dex has profound and varied effects on the expression of matrix proteins produced by human bone marrow stromal cells. With the induced increment in alkaline phosphatase correlating with the mineralization effects of Dex, the observed concomitant decrease in osteopontin and bone sialoprotein mRNA levels and the associated decline of osteocalcin are consistent with the hypothesis that the regulation of the expression of these highly negatively charged proteins is essential in order to maximize the Dex-induced mineralization process conditioned by normal human bone marrow stromal osteoprogenitor cells.

Adolescent↗
PubMed1994

Stimulation of human osteoblast differentiation and function by ipriflavone and its metabolites.

Ipriflavone (IP), an isoflavone derivative, has been shown to interfere with bone remodeling by inhibiting bone resorption and perhaps stimulating bone formation. In this study, we have analyzed the effect of IP and its metabolites on the differentiation and function of human osteoblastic cells. Bone marrow stromal osteoprogenitor cells (BMC) and trabecular bone osteoblasts (HOB) were isolated from human donors. The former can be induced to differentiate by treatment with dexamethasone, whereas the latter represent a more differentiated osteoblast. Incubation of BMC with metabolite III (10(-5) M) for 1 week induced modest but significant changes of alkaline phosphatase activity. Though both IP and metabolite III stimulated the expression of bone sialoprotein mRNA, a protein involved in cell attachment to the matrix, only metabolite III increased the steady-state level of decorin mRNA, a collagen fibrillogenesis-regulating proteoglycan. Metabolites III and V, but not the other isoflavones, increased the expression of type I collagen mRNA in HOB, whereas no detectable changes were observed in BMC cells with any of the experimental compounds. In HOB, an increased abundance of osteopontin and bone sialoprotein mRNA were also obtained after 1-week treatment with IP or metabolite V. No appreciable effects of IP or its metabolites were seen on osteocalcin expression and synthesis by either cell type. Finally, IP consistently increased the amount of 45Ca incorporated into the cell layer by BMC, and stimulated mineralization of both BMC and HOB, assessed by von Kossa staining. Thus, IP and its metabolites regulate the differentiation and biosynthetic properties of human bone-forming cells by enhancing the expression of some important matrix proteins and facilitating the mineralization process.

Alkaline Phosphatase↗
PubMed1994

Differentiation of human bone marrow osteogenic stromal cells in vitro: induction of the osteoblast phenotype by dexamethasone.

Human bone marrow stromal cells were examined for their osteogenic potential in an in vitro cell culture system. Dexamethasone (Dex) treatment induced morphological transformation of these cells from an elongated to a more cuboidal shape, increased their alkaline phosphatase activity and cAMP responses to PTH and prostaglandin E2, and was essential for mineralization of the extracellular matrix. Dex-induced differentiation of human bone marrow stromal cells was apparent after 2-3 days of treatment and reached a maximum at 7-14 days, as judged by alkaline phosphatase activity, although induction of osteocalcin by 1,25-dihydroxyvitamin D3 was attenuated by Dex. Withdrawal of Dex resulted in an enhancement of the 1,25-dihydroxyvitamin D3-induced secretion of osteocalcin, whereas alkaline phosphatase activity and the cAMP response to PTH remained at prewithdrawal levels. The steady state mRNA level of osteonectin was not affected by Dex. Our results, which demonstrate that Dex conditions the differentiation of human bone marrow osteogenic stromal cells into osteoblast-like cells, support the hypothesis of a permissive effect of glucocorticoids in ensuring an adequate supply of mature osteoblast populations. Furthermore, the established human bone marrow stromal cell culture provides a good model of an in vitro system to study the regulation of differentiation of human bone osteoprogenitor cells.

Adult↗
PubMed1994

The effect of glucocorticoid on the synthesis of biglycan and decorin in human osteoblasts and bone marrow stromal cells.

We have previously demonstrated that glucocorticoids induce differentiation of human bone marrow stromal cells (BMSC) into cells expressing mature osteoblast phenotype. As glucocorticoids have marked effects on extracellular matrix protein synthesis in bone, and because proteoglycans are important components of bone matrix and may condition the differentiation and biological activities of osteoblasts, we studied the effects of dexamethasone (Dex) on the synthesis of small proteoglycans [decorin (DCN) and biglycan (BGN)] in adult human BMSC and human osteoblasts (HOB). First passaged HOB and BMSC were treated with either ethanol or 10(-7) M Dex for 7 days. After treatment, the cells were metabolically labeled with either [35S]SO4 alone or [35S]SO4 and [3H]leucine together for 24 h. Conditioned media were collected, and cell layers were extracted with 4 M guanidine HCl. The extracts and conditioned media were subjected to gel filtration and ion exchange chromatography. Fractions containing radiolabeled proteoglycans were analyzed either directly or after immunoprecipitation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Dex treatment resulted in a dramatic increase in DCN and an associated decrease in BGN in both the conditioned medium and the cell layer of HOB cultures. In Dex-treated BMSC cultures, BGN was decreased in both the conditioned medium and cell layer, whereas DCN was stimulated in the majority of cultures. Northern blot analysis indicated that steady state messenger RNA (mRNA) concentration of DCN was increased by Dex in all of the HOB cultures and in seven of eight BMSC cultures analyzed. The steady state mRNA level of BGN was decreased by Dex in both HOB and BMSC cultures. The regulation of DCN and BGN mRNA by Dex in both HOB and BMSC (when responsive) was dose dependent. Time-course analysis indicated that as little as 1 day of treatment with Dex was sufficient to decrease BGN mRNA and increase DCN mRNA (when observed) levels in BMSC; the regulation spanned a 4-week interval, during which the extracellular matrix of BMSC was mineralized. The effect of Dex on the steady state mRNA levels of DCN and BGN in HOB was also apparent after 1 day of treatment. These accumulated results suggest that Dex modulates the synthesis of small proteoglycans in both human bone marrow stromal osteoprogenitor cells and mature osteoblasts.

Biglycan↗
PubMed1994

[A clinical analysis of pupillary membrane formation after intraocular lens implantation].

In 540 cases having undertaken extracapsular cataract extraction and intraocular lens implantation, a pupillary membrane developed in 76 cases, the rate of occurrence being 14%. Generally, the membrane appears on the fifth post-operative day and corticosteroids are effective in its treatment. After treatment no significant sequela is left and the corrected postoperative visual acuity is not affected. The pathogenesis, treatment and prognosis of the pupillary membrane are briefly discussed in the report.

Adolescent↗
PubMed1994

[Infection of acid-fast bacterial L-forms].

One hundred and fifty five cases which pathological diagnosis were chronic lymphadenitis were studied in order to detect infection of acid-fast bacterial L-forms by Ziehl-Neelsen (ZN), intensified kinyoun (IK) and immunohistochemical staining (PAP). The results showed that the expression of M-tuberculosis antibody was positive in 106 cases (68.4%). Among them, 94 cases (60.6%) were positive in IK staining. The positive rate of acid-fast bacillus was 0.6% (1 case), of L-forms was 60% (93 cases). L-forms are higher pleomorphic, spherical bodies, giant bodies or long filaments were shown. The L-forms mostly localised within macrophages, only a few distributed sporadically. The possible causes of misdiagnosis physician and pathologist were discussed. The prognostic value was also suggested.

Antibodies, Bacterial↗