Biomedical subjects

S Feng

Publications and source records attributed to S Feng.

At least 55 records · Page 3Linked to original sources

PubMed2000

Cytoplasmic domains of GpIbalpha and GpIbbeta regulate 14-3-3zeta binding to GpIb/IX/V.

Shear stress causes the platelet glycoprotein (Gp) Ib/IX/V to bind to von Willebrand factor, resulting in platelet adhesion. GpIb/IX/V also functions to stimulate transmembranous signaling, leading to platelet activation and the expression of a ligand-receptive GpIIb-IIIa complex. The highly conserved cytoplasmic domain of GpIbalpha binds directly to a dimeric 14-3-3 adapter protein zeta isoform. To explore structural determinants of GpIb/IX/V binding to 14-3-3zeta, the authors examined 14-3-3zeta interactions with GpIbalpha and GpIbbeta in heterologous cells and platelets. Truncations of GpIbalpha at amino acid 542 or 594, or deletions of residues 542 through 590, inhibited binding of 14-3-3zeta. Deletion of GpIbalpha from Trp(570) to Ser(590) eliminated 14-3-3zeta binding, and deletion of the sequence from Arg(542)-Trp(570) enhanced binding of 14-3-3zeta to GpIbalpha. All GpIbalpha mutations that eliminated GpIbalpha binding to the GST-14-3-3zeta fusion protein also eliminated GpIbbeta binding to the fusion protein. Forskolin treatment of Chinese hamster ovary cells expressing wild-type GpIbalpha/beta/IX resulted in the phosphorylation of GpIbbeta associated with enhanced binding of GpIbbeta to GST-14-3-3zeta fusion protein and increased 14-3-3zeta coimmunoprecipitated with GpIbalpha. When intact human platelets aggregated in response to 90 dynes/cm(2) shear stress, 14-3-3zeta disassociated from GpIbalpha. Prostacyclin treatment of platelets inhibited shear stress-induced aggregation and the release of 14-3-3zeta from GpIbalpha. These data demonstrate that amino acid residues in the cytoskeletal interaction domains of GpIbalpha regulate 14-3-3zeta binding to GpIbalpha/beta/IX, and suggest that protein kinase A-dependent phosphorylation of GpIbbeta enhances 14-3-3zeta binding to the GpIb/IX/V complex in human platelets. (Blood. 2000;95:551-557)

14-3-3 Proteins↗

PubMed2000

Basal lamina of avian ovarian follicle: influence on morphology of granulosa cells in-vitro.

Experiments were conducted to determine the influence of basal lamina on the morphology of ovarian granulosa cells in vitro. Pure and intact basal lamina was isolated from the large preovulatory follicles of the chicken ovary and designated basal lamina of avian ovarian follicle (BLAOF). Examination of the isolated basal lamina with electron microscope revealed an ultrastructure that is similar to that of basal lamina in the intact ovarian follicle. Pieces of the intact basal lamina were attached to the bottom of 32 mm culture dishes (BLAOF-coated dishes) in which differentiated granulosa cells isolated from the largest preovulatory follicle or undifferentiated granulosa cells isolated from immature small yellow chicken ovarian follicles were cultured; uncoated dishes served as controls. Granulosa cells incubated on intact basal lamina assumed spherical shape, whereas granulosa cells incubated directly on plastic in control dishes became highly flattened. Interestingly, granulosa cells that attached to plastic close to BLAOF (in BLAOF-containing dishes) became rounded. The storage of BLAOF-coated culture dishes at 4 degrees C for 2 years had no apparent effect on its ability of the matrix material to induce changes in granulosa cell shape. Some components of the basal lamina could be solubilized with guanidine-HCl alone (fraction 1; 90-95% of total protein in BLAOF) with the remaining components solubilized with beta-mercaptoethanol containing guanidine-HCl (fraction 2; 5-10% of total protein in BLAOF). Differentiated and undifferentiated chicken granulosa cells became rounded when incubated in fraction 1-pre-coated wells; whereas those incubated directly on plastic in control wells were flattened. Similarly, when fraction 1 of solubilized basal lamina was added as liquid to incubation mixture, it caused both differentiated and undifferentiated granulosa cells to assume spherical shapes. The storage of fraction 1-coated culture dishes at 4 degrees C for 12 or more months had no apparent effect on its ability to influence granulosa cell shape. Fraction 1-induced changes in granulosa cell shape were similar to those observed for complete and intact basal lamina (BLAOF). These findings demonstrate that intact homologous basal lamina (BLAOF) or its solubilized (fluidized) form can induce normal (in vivo) morphology in granulosa cells. It is suggested that BLAOF or its solubilized form can be used to culture cells in experiments designed to examine the influence of the natural basal lamina microenvironment on cellular behavior and function.

Animals↗

PubMed2000

Establishment of a pure culture of distinct cell types from bovine placental cotyledon.

Methods are described to establish distinct cell cultures from bovine placental cotyledon. The villous tissue of the bovine placental cotyledon is collected and dissociated with 0.125% trypsin. The cells are then cultured in three different media: a serum-free medium, a growth factor supplemented medium, and a medium with 10% serum. A polygonal cell line grew out of the serum-containing medium, a fan-shaped cell line grew out of the serum-free medium, and an epitheloid cell line grew out of the growth factor supplemented medium. These cells maintained their morphology when grown in serum containing medium. The preference of distinct cells for different media in vitro reflects the in vivo physiological regulation of these cells. These distinct cultures re ideal to study the extrinsic and interactive factors in bovine placenta.

Animals↗

PubMed2000

Stability of Borrelia burgdorferi outer surface protein C under immune selection pressure.

Outer surface protein (Osp) C immune pressure during persistent infection with Borrelia burgdorferi was examined in relation to genetic variation of ospC. Mice were infected with clonal B. burgdorferi sensu stricto (s.s.) N40 or B. afzelii PKo and then were hyperimmunized with homologous recombinant OspC or with decorin-binding protein A (DbpA) (controls). After 6 months, B. burgdorferi isolates were subjected to restriction enzyme analysis of the amplified ospC genes and were found to have no differences among 9 B. burgdorferi s.s. N40 and 9 B. afzelii PKo isolates from OspC hyperimmune mice or among 10 B. burgdorferi s.s. N40 and 10 B. afzelii PKo isolates from DbpA hyperimmune mice, compared with input inocula. Comparison of gene sequences among 4 B. burgdorferi s.s. N40 and 9 B. afzelii PKo isolates from OspC-immunized mice revealed no ospC variation from input inocula. Variation in ospC among B. burgdorferi isolates and species during chronic infection is not likely to be an important mechanism for immune evasion.

Adhesins, Bacterial↗

PubMed2000

Simultaneous analysis of delta9-THC and its major metabolites in urine, plasma, and meconium by GC-MS using an immunoaffinity extraction procedure.

A simple extraction procedure for delta9-tetrahydrocannabinol (delta9-THC) and its metabolites from various biological specimens was developed based on immunoaffinity chromatography. Using the affinity resin prepared by immobilization of THC antibody onto cyanogen bromide-activated Sepharose 4B, delta9-THC and its major metabolites including 11-nor-delta9-THC-9-carboxylic acid (delta9-THCCOOH), 11-hydroxy-delta9-THC (11-OH-delta9-THC), and 8beta,11-dihydroxy-delta9-THC (8beta,11-diOH-delta9-THC) were extracted simultaneously from plasma or urine after enzyme hydrolysis. The samples were derivatized as TMS derivatives and analyzed by gas chromatography-mass spectrometry in EI mode with SIM monitoring. Greater than 87% extraction recovery of the four analytes was obtained from both plasma and urine at 5 and 50 ng/mL concentration levels. The method was also used for meconium analysis with some modification. The extraction recovery from meconium, however, was lower than that of plasma and urine, ranging from 52 to 72% at the 10-ng/g level. All compounds showed good linearity within the tested ranges up to 100 ng/mL (g). The limits of detection ranged from 0.5 to 2.5 ng/mL in plasma and urine, and from 1.0 to 2.5 ng/g in meconium. Analysis of 24 meconium specimens showed that 11-OH-delta9-THC is indeed an important metabolite in meconium.

Chromatography, Affinity↗

PubMed2000

Spatiotemporal structure of isodiffracting ultrashort electromagnetic pulses

We present a model of isodiffracting single-cycle and few-cycle ultrashort electromagnetic pulses. The model is based on exact solutions of the time-dependent paraxial wave equation with space-time coupling effects included. The spatiotemporal structure of these pulses is characterized by a scaling parameter which relates off-axis pulse shapes to the axial temporal waveforms. Depending on the spectrum a pulse may transform itself from a single-cycle pulse to a multicycle pulse along the radial coordinate. This model is also used to describe recirculating pulses in a curved mirror cavity resonator. The Gouy phase shift contributes an absolute phase that results in a pulse-to-pulse temporal instability.

Journal Article↗

PubMed2000

The galE gene of Campylobacter jejuni is involved in lipopolysaccharide synthesis and virulence.

Lipopolysaccharide (LPS) is one of the main virulence factors of gram-negative bacteria. The LPS from Campylobacter spp. has endotoxic properties and has been shown to play a role in adhesion. We previously cloned a gene cluster (wla) which is involved in the synthesis of the Campylobacter jejuni 81116 LPS molecule. Sequence alignment of the first gene in this cluster indicated similarity with galE genes. These genes encode a UDP-glucose 4-epimerase, which catalyzes the interconversion of UDP-galactose and UDP-glucose. A Salmonella galE mutant was transformed with the galE gene from C. jejuni. The LPS analysis of wild-type, galE, and complemented galE Salmonella strains showed that the C. jejuni galE gene could restore the smooth wild-type Salmonella LPS. A UDP-glucose 4-epimerase assay was used to demonstrate that the galE gene from C. jejuni encoded this epimerase. We constructed a C. jejuni galE mutant which expressed a lipid A-core molecule of reduced molecular weight that did not react with antiserum raised against the parental strain. These results show an essential role for the galE gene in the synthesis of C. jejuni LPS. The galE mutant also showed a reduction in its ability to adhere to and invade INT407 cells. However, it was still able to colonize chickens to the same level as the wild-type strain. The serum resistance and hemolytic activity of this mutant were not changed compared to the parent strain. The ability of the mutant to take up DNA and integrate it in its genome was reduced 20-fold. These results show that LPS of C. jejuni is an important virulence factor.

Amino Acid Sequence↗

PubMed2000

Lyme arthritis resolution with antiserum to a 37-kilodalton Borrelia burgdorferi protein.

A 37-kDa protein from Borrelia burgdorferi (the agent of Lyme disease) was identified as a target for immune-mediated resolution of Lyme arthritis. Studies in a mouse model have shown that arthritis resolution can be mediated by antibodies (against unknown target antigens) within immune sera from actively infected mice. Immune sera from infected mice were therefore used to screen a B. burgdorferi genomic expression library. A gene was identified whose native product is a putative lipoprotein of approximately 37 kDa, referred to here as arthritis-related protein (Arp). Active and passive immunization of mice with recombinant Arp or Arp antiserum, respectively, did not protect mice from challenge inoculation. However, when Arp antiserum was administered to severe combined immunodeficient (SCID) mice with established infections and with ongoing arthritis and carditis, treatment selectively induced arthritis resolution without affecting the status of carditis or influencing the status of infection, including spirochetemia. The selective arthritis-resolving effect of Arp antiserum mimics the activity of immune serum from immunocompetent mice when such serum is transferred into SCID mice with established infections. The arp gene could not be amplified from unrelated B. burgdorferi isolates but hybridized with those isolates only under very-low-stringency conditions. Arp antiserum reacted against proteins of similar size in a wide range of B. burgdorferi isolates.

Animals↗

PubMed2000

Interaction of PIP(2) with the XIP region of the cardiac Na/Ca exchanger.

The sarcolemmal Na/Ca exchanger undergoes an inactivation process in which exchange activity decays over several seconds following activation by the application of Na to the intracellular surface of the protein. Inactivation is eliminated by an increase in membrane phosphatidylinositol 4,5-bisphosphate (PIP(2)). Inactivation is also strongly affected by mutations to a basic 20-amino acid segment of the exchanger known as the endogenous XIP region. The hypothesis that PIP(2) directly interacts with the XIP region of the exchanger was tested. First, we investigated the ability of a peptide with the same sequence as the XIP region to bind to immobilized phospholipid vesicles. (125)I-labeled XIP bound avidly to vesicles containing only a low concentration (<3%) of PIP(2). The binding was specific, in that binding was not displaced by other basic peptides. The effects of altering the sequence of XIP peptides also indicated binding specificity. Second, we examined the functional response to PIP(2) of exchangers with mutated XIP regions. Outward Na/Ca exchange currents were measured using the giant excised patch technique. The mutated exchangers either had no inactivation or accelerated inactivation. In both cases, the exchangers no longer responded to PIP(2) or to PIP(2) antibodies. Overall, the data indicate that the affinity of the endogenous XIP region for PIP(2) is an important determinant of the inactivation process.

Animals↗

PubMed2000

Endothelial-like cells from the bovine placental cotyledon.

A cell-line was established from bovine placental cotyledon. When cultured in M199 with 10% fetal bovine serum, this cell-line had a doubling time of about 18 h. With immunohistochemistry, it was demonstrated that this cell-line expressed vimentin and angiotensin-converting enzyme (ACE). While both molecules are expressed in endothelial cells, ACE is usually considered to be a specific marker for endothelial cells. Furthermore, cells were shown to take up Dil-Ac-LDL (acetylated low-density lipoprotein labeled with 1,1'-dioctadecyl-3,3,3'-tetramethylindo-carbocyanine perchlorate). This characteristic feature has been used to identify endothelial cells. Finally, when cultured on matrigel, this cell-line formed tube-like structures similar to those formed by endothelial cells. Tube-formation on matrigel is a physiological property specific to endothelial cells. In conclusion, these three lines of evidence strongly suggest that this cell-line is endothelial cell in nature. Further studies using an endothelial cell-line from bovine placenta may help to elucidate the cause of bovine placental retention, a major cause for economic loss in bovine industry. Furthermore, an endothelial cell-line could be an important tool in research areas such as tissue remodeling, angiogenesis, and cancer.

Animals↗

PubMed2000

No correlation of polymorphism of angiotensin-converting enzyme genes with left ventricular hypertrophy in essential hypertension.

To investigate the correlation of polymorphism of angiotensin-converting enzyme (ACE) genes with left ventricular hypertrophy in essential hypertension, 151 patients with essential hypertension were studied. ACE genotypes were determined by PCR technology and diastolic left ventricular diameter (DLVd), systolic left ventricular diameter (SLVd), interseptal ventricular thickness (IVS), and left ventricular posterior wall thickness (LVPW) were scanned by echocardiography. Left ventricular mass (LVM) and the left ventricular mass index (LVMI) were calculated from echocardiographic findings. Results revealed that DLVd, SLVd, IVS, LVPW, LVM, and LVMI of the DD genotype group were 49.9 +/- 5.6 mm, 30.5 +/- 6.5 mm, 11.2 +/- 1.6 mm, 11.7 +/- 1.5 mm, 259.5 +/- 62.1 g, 92.7 +/- 23.5 g/m2, respectively. DLVd, SLVd, IVS, LVPW, LVM, and LVMI of the ID genotype group were 8.9 +/- 5.3 mm, 31.5 +/- 5.2 mm, 11.4 +/- 1.7 mm, 11.9 +/- 1.6 mm, 261.3 +/- 70.3 g, and 94.9 +/- 25.8 g/m2, respectively, and DLVd, SLVd, IVS, LVPW, LVM, and LVMI of the II genotype group are 48.9 +/- 5.5 mm, 31.8 +/- 6.5 mm, 11.1 +/- 1.9 mm, 11.5 +/- 1.8 mm, 250.8 +/- 82.5 g and 90.8 +/- 30.1 g/m2 respectively. There was no significant difference between the ID, DD and II genotype groups as regards DLVd, SLVd, IVS, LVPW, LVM, and LVMI (p > 0.05). These findings indicate that there is no association between the ACE gene and left ventricular hypertrophy in essential hypertension occurring in the Chinese population.

Aged↗

PubMed2000

Cavity phase engineering for stable enhanced terahertz pulse trains.

We show that the cavity round-trip Gouy phase leads to pulse-to-pulse variation of the absolute phase and temporal profile of circulating few- or single-cycle pulses in empty resonators. This pulse-to-pulse variation can be eliminated by the proper insertion of a lens into the cavity. An application to terahertz resonators with phase-locked feedback is discussed.

Journal Article↗

PubMed2000

[The association and linkage analysis between the FcgammaR II a-131 and system lupus erythematosus].

OBJECTIVE: To shed light on the relationship between FcgammaR II a-131 and systemic lupus erythematosus(SLE) in southern Chinese Han population. METHODS: A population-based and family-based study was carried out. FcgammaR II a-131 of each subject was measured by using PCR-allele specific oligonucleotide hybridization(ASO) method. RESULTS: (1) The distribution of FcgammaR II A-131 genotype in cases is significantly different from that in controls (P<0.05). So is the frequency of FcgammaR II aR-131 allele (P < 0.01) which suggests that subjects who have R131 allele tend to be more susceptible to SLE. The subjects with R/R131 homozygous genotype have a higher risk of suffering from SLE. (2) The distribution of FcgammaR II a-131 varies in different races, with identical distribution type among Chinese and Japanese. (3) The results of family-based association analysis and transmitted/disequilibrium test(TDT) suggest that there is not any linkage evidence between FcgammaR II a-131 and SLE. Possibly, the sample size was too small to get positive result. CONCLUSION: This study suggests that FcgammaR II a-131 is a major factor predisposing to the development of SLE in southern Chinese Han population.

Alleles↗

PubMed2000

[Evaluation of derma and fat combined pedicled superficial temporal fascia flap for reconstruction of facial depression].

OBJECTIVE: To evaluate the curative effect of derma and fat combined pedicled superficial temporal fascia flap for reconstruction of facial depression. METHOD: Postoperative follow-up and comparative study were performed. 10 cases of facial depression deformities were involved, in which 5 cases were hemifacial atrophy, and 5 cases were branchial arch maldevelopment. RESULTS: Postoperative follow-up for 1-3 years showed that the method produced better results in branchial arch depression than in hemifacial atrophy. The combined tissue used in plomb of branchial arch maldevelopment had a low ratio of anaphase absorption, maintaining a satisfactory long-term full contour. In plomb of hemifacial atrophy, the anaphase absorption ratio of the was combined tissue approximately 20%-40%. CONCLUSIONS: The noxa of depression ought to be noticed when this method is used in reconstruction of facial depression. The exorbitant plomb is inadvisable for facial depression of branchial arch maldevelopment. However, in facial depression of hemifacial atrophy, in considering anaphases absorption, the suitable exorbitant plomb is reasonable for better future results.

Adolescent↗

PubMed2000

[Effect of Bacillus megaterium on Gluconobacter oxydans in mixed culture].

To reveal the relationship between Bacillus megaterium and Gluconobacter oxydans in the mixed culture of vitamin C two-step fermentation, the effect of B. megaterium on the growth of G. oxydans and its synthesizing ability of 2-keto-L-gulonic acid(2KGA) was studied. The bioactive metabolites which could enhance the synthesis of 2KGA were isolated and purified by ultrafiltration, gel chromatography and SDS-polyacrylamide gel electrophoresis. Both the culture supernatant and the cytosol of B. megaterium could promote the proliferation of G. oxydans, and the active component in the culture supernatant was above 100 KDa. The culture suernatant could enhance the conversion of L-sorbose to 2KGA, while the cytosol could not. The active components in B. megaterium culture supernatant had molecular weight of 30-50 KDa and above 100 KDa, and the former was a kind of protein with an apparent molecular weight of about 35 KDa, which consisted of one sort of subunit and contained Fe and Zn elements.

Antibiosis↗

PubMed2000

Decreased bone mineral density in female patients with systemic lupus erythematosus after long-term administration of Tripterygium Wilfordii Hook. F.

OBJECTIVE: To investigate the possible bone changes in female patients with systemic lupus erythematosus (SLE) induced by long-term administration of Tripterygium Wilfordii Hook. F (TW). METHODS: 70 female SLE patients were divided into 4 groups according to their drug history: SLE disease control group, corticosteroids treatment group, TW treatment group, and both corticosteroids and TW treatment group. Bone mineral density (BMD) of the lumbar spine 2-4 and biochemical markers of bone turnover were studied. RESULTS: Long-term administration of TW could significantly decrease BMD levels in female SLE patients (P < 0.05). The patients receiving TW for more than 5 years had significantly lower BMD levels compared with those for less than 5 years. The degree of decreased BMD induced by TW was less severe compared with that of prednisone. No significant differences were observed in the biochemical markers of bone turnover among four groups (P > 0.05). CONCLUSION: Long-term administration of TW could decrease BMD levels in women. Osteoporosis may be an important problem for SLE patients treated with TW.

Adult↗

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

[The impact of hepatitis B virus infected patients or donors on the outcome of hematopoietic stem cell transplantation].

OBJECTIVE: To investigate the impact of recipients and/or donors infected with hepatitis B on the outcome of hematopoietic stem cells transplantation (HSCT). METHODS: We analyzed retrospectively the transplantation outcome in 26 of 164 hematological diseases patients who and whose donors were infected with hepatitis prior to transplantation. RESULTS: (1) Three of the 26 patients developed VOD after HSCT, the incidence (11.5%) is significant higher than that in patients and donors who did not infected with HBV (P < 0.05). (2) Two of 5 patients transfused hematopoietic stem cells from HBsAg + donors developed hepatitis B. (3) Four patients with allogeneic stem cell transplantation developed hepatic failure (HF) which occurred during cyclosporin (CsA) being tapered off or withdrawal. The incidence of HF in patients and/or donors infected with HBV (15.4%) is obviously higher than that in patients and donors who did not (0.08%, P < 0.01). (4) In 4 patients with HbeAg +, 2 patients died of HF after allogeneic HSCT, the other 2 patients survived after autologous HSCT. CONCLUSION: Donors and recipients infected with hepatitis B are not contraindication of HSCT, but patients with allogeneic HSCT are in danger to develop LF during CsA being tapered off or withdrawal.

Adolescent↗