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Biomedical subjects

S Huang

Publications and source records attributed to S Huang.

At least 361 records · Page 20Linked to original sources
PubMed1997

Control of fibronectin receptor expression by fibronectin: antisense fibronectin RNA downmodulates the induction of fibronectin receptor by transforming growth factor beta1.

The results of our previous studies of mouse embryo fibroblasts showed that fibronectin expression and fibronectin receptor expression are tightly coregulated and that fibronectin modulates expression of its receptor in response to treatment with the differentiation-inducing agent N,N,-dimethylformamide (Varani and Chakrabarty, 1990, J. Cell. Physiol., 143:445-454; Huang et al., 1994, J. Cell. Physiol., 161:470-482). We also found that transforming growth factor beta1 (TGFbeta1) induces a more differentiated phenotype in the epithelium-derived human colon carcinoma cell line Moser and upregulates the expression of both fibronectin and its receptor (Huang and Chakrabarty, 1994, Int. J. Cancer, 57:742-746). By expressing antisense fibronectin RNA in Moser cells, we have downregulated fibronectin mRNA expression and thus blocked the ability of TGFbeta1 to induce fibronectin expression (Huang and Chakrabarty, 1994, J. Biol. Chem., 269:28764-28768). In this study, we examined the effect of antisense fibronectin RNA expression on the induction of fibronectin receptor by TGFbeta1 and tested the hypothesis that the induction of fibronectin expression by TGFbeta1 is required for the induction of fibronectin receptor expression. Blocking fibronectin induction by TGFbeta1 attenuated the ability of TGFbeta1 to upregulate the expression of cell-surface fibronectin receptors, alpha5beta1 integrin expression, and adhesion to extracellular matrix fibronectin. We therefore conclude that induction of fibronectin expression is required for optimal upregulation of fibronectin receptor expression by TGFbeta1.

Animals↗
PubMed1997

In vitro analysis of oocyte cumulus complex pickup rate in the hamster Mesocricetus auratus.

In mammals, the oocyte and its surrounding cumulus cells constitute on oocyte cumulus complex (OCC). During ovulation, OCCs are extruded into the peritoneal or bursal cavity, depending on the species, and are then rapidly picked up by the fimbria on the outer surface of the oviductal infundibulum and transported to the ampulla, where fertilization occurs. We developed a method to measure OCC pickup rates quantitatively in vitro, and we used this method to evaluate the effects of viscosity and temperature on pickup rates. Hamster infundibula are placed in a holding pipette in a chamber modified to study OCC pickup. Ciliary beat frequencies (CBF) can be measured in the same preparation. Pickup rates vary depending on the pathway on which the OCC travels over the surface of the infundibulum; however, rates for a given pathway are very consistent. The average pickup rate at room temperature calculated from three different pathways/infundibulum was 55.2 +/- 10.6 microns/sec. Both rates between infundibula from the same female and rates among infundibula from different females were in most cases similar. Preparations preincubated in vitro for 2.75 hr produced rates similar to nonpreincubated samples, while longer preincubation resulted in decreased rates. Inclusion of Ficoll in culture medium to increase viscosity caused a concentration-dependent decrease in both OCC pickup rate and in CBF. However, a significant decrease in OCC pickup rate was only observed at viscosities higher than those found in bursal fluid. When trials were run at physiological temperature (36.4 degrees C) rather ambient temperature, rates increased to 136.7 +/- 29.9 (SD) microns/sec. Linear regression analysis demonstrated a strong positive correlation (r = 0.94) between OCC pickup rate and temperature. The OCC pickup rate assay can be used experimentally, and should be valuable in evaluating factors that affect rate and in studies dealing with the mechanism of OCC pickup.

Animals↗
PubMed1997

Extended resection for locally advanced colorectal carcinoma.

BACKGROUND: The purpose of this study was to determine the therapeutic benefit of multivisceral resection (MVR) in patients with locally advanced colorectal carcinomas. METHODS: The study population was composed of 118 patients whose resection of the primary lesion included one or more adhesed adjacent secondary organs or structures (ASOS). Tumors were staged as B3 (T4,N0) and as C3 (T4,N1-3). Adhesions were classified as invasive (B3+,C3+) or inflammatory (B3-, C3-). RESULTS: Sixty-four patients were staged B3 and 54 C3. Eighty-one were classified B3+/C3+. Fifty-nine percent of patients had ASOS resected, 29% had two resected, and the remaining 12% had three or four resected. Actuarial 5-year survival rates were 62% and 38% (p = 0.017) for B3 and C3 lesions, respectively. The 5-year survival rates were 78% for patients with B3- tumors and 58% for those with B3+ tumors (p = 0.043), and 34% for patients with C3+ tumors and 64% for those with C3- tumors (p = NS). The 5-year survival rates were 71% for patients with B3-/C3- tumors and 47% for those with B3+/C3+ tumors (p = NS). The 5-year survival rates after resection of one ASOS, two ASOS, and three or four ASOS were 52%, 55%, and 38%, respectively (P = NS). CONCLUSIONS: There is no statistically significant difference in the 5-year survival rates when multiple ASOS are resected; therefore, an aggressive surgical approach is warranted.

Adenocarcinoma↗
PubMed1997

Another pedigree with pure autosomal dominant spastic paraplegia (AD-FSP) from Tibet mapping to 14q11.2-q24.3.

The mutant in a family with autosomal-dominant spastic paresis in Northern Tibet was mapped by linkage analysis with several microsatellite markers to a gene locus at 14q11.2-q24.3, an area to which a few mutants leading to a condition with similar clinical signs have previously been mapped. The mutant observed in this pedigree probably arose de novo. Gene loci at 2p21-p24 and 15q, which have been found for other pedigrees with dominant spastic paresis, were excluded. The data in this pedigree do not contradict the hypothesis proposed by another group that there might be anticipation.

Adult↗
PubMed1997

Apoptosis signaling pathway in T cells is composed of ICE/Ced-3 family proteases and MAP kinase kinase 6b.

Fas/APO-1(CD95) ligation activates programmed cell death, a cellular process that plays an important role in the maturation of the host immune response. We show that activation of a specific MAP kinase kinase (MKK), MKK6b, is necessary and sufficient for Fas-induced apoptosis of Jurkat T cells. MKK6b activation occurs downstream of an interleukin-1 converting enzyme-like (ICE-like) protease(s), while execution of the apoptotic pathway by MKK6b requires both ICE- and CPP32-like proteases. Surprisingly, the p38 MAP kinase protein, a known substrate of MKK6b, does not participate in Fas/MKK6b-mediated apoptosis. These findings indicate a divergence of the MKK6b signaling pathways, one of which activates p38 and leads to regulation of gene expression, and one of which activates the ICE/Ced-3 family of proteases and leads to cell death. These studies represent a demonstration of an apoptotic pathway that is comprised of both the ICE/Ced-3 family of proteases and MAP kinase kinase 6.

Amino Acid Sequence↗
PubMed1997

Isolation and structure determination of sulfonoquinovosyl dipalmitoyl glyceride, a P-selectin receptor inhibitor from the alga Dictyochloris fragrans.

Bioassay-guided fractionation of the marine alga Dictyochloris fragrans led to the isolation and identification of sulfonoquinovosyl dipalmitoyl glyceride (1). The structure of 1 was determined by a combination of spectroscopic methods. On the basis of P-selectin inhibition assays (i.e., P-selectin-IgG ELISA, cell binding assay of receptor globulin, and platelet:HL60 adhesion, it was demonstrated that 1 selectively blocks the P-selectin-ligand interaction in vitro and could be considered a lead compound for synthetic modification in order to design more potent inhibitors of cell adhesion processes that play important roles in development of inflammatory-mediated disease states.

Cell Adhesion↗
PubMed1997

Bripiodionen, a new inhibitor of human cytomegalovirus protease from Streptomyces sp. WC76599.

Bripiodionen (1), a new natural product, was isolated from Streptomyces sp. WC76599 during the screening of microbial fermentation extracts for their ability to inhibit human cytomegalovirus protease. The structure of 1 was elucidated by spectroscopic methods. Compound 1 displayed inhibitory activity against human cytomegalovirus protease with an IC50 value of 30 microM.

Animals↗
PubMed1997

The Arabidopsis ACT11 actin gene is strongly expressed in tissues of the emerging inflorescence, pollen, and developing ovules.

ACT11 represents a unique and ancient actin subclass in the complex Arabidopsis actin gene family. We have isolated and characterized the Arabidopsis ACT11 actin gene and examined its expression. Southern blotting with a 5' gene-specific probe showed that ACT11 was a single-copy gene in the genome. Northern analysis with a 3' gene-specific probe and reverse transcriptase-mediated PCR (RT-PCR) using gene-specific primers detected ACT11 mRNA at low levels in seedling, root, leaf, and silique tissue; at moderate levels in the inflorescence stem and flower; and at very high levels in pollen. The 5' region of the ACT11 gene, including the promoter region, the 5'-untranslated leader, the intron within the leader, and the first 19 actin codons, was fused to a beta-glucuronidase (GUS) reporter gene. The expression of the ACT11/GUS fusion was examined histochemically in numerous independent transgenic Arabidopsis plants. Strong ACT11/GUS activity was detected in rapidly elongating tissues and organs (e.g., etiolated hypocotyls, expanding leaves, stems) and in floral organ primordia. As the floral buds developed into mature flowers, strong GUS activity was gradually restricted to mature pollen and developing ovules. ACT11 appears to be the only Arabidopsis actin gene expressed at significant levels in ovule, embryo, and endosperm. The unique expression patterns in reproductive organs and the sequence divergence of the ACT11 actin gene suggest that the ACT11 isovariant plays distinct and required roles during Arabidopsis development.

Actins↗
PubMed1997

High resolution solution structure of ribosomal protein L11-C76, a helical protein with a flexible loop that becomes structured upon binding to RNA.

The structure of the C-terminal RNA recognition domain of ribosomal protein L11 has been solved by heteronuclear three-dimensional nuclear magnetic resonance spectroscopy. Although the structure can be considered high resolution in the core, 15 residues between helix alpha 1 and strand beta 1 form an extended, unstructured loop. 15N transverse relaxation measurements suggest that the loop is moving on a picosecond-to-nanosecond time scale in the free protein but not in the protein bound to RNA. Chemical shifts differences between the free protein and the bound protein suggest that the loop as well as the C-terminal end of helix alpha 3 are involved in RNA binding.

Amino Acid Sequence↗
PubMed1997

Biochemical characterization and histochemical localization of nitric oxide synthase in the nervous system of the snail, Helix pomatia.

Nitric oxide synthase (NOS) in the snail Helix pomatia was characterized by biochemical and molecular biological techniques and localized by histochemical methods. Central ganglia contained particulate paraformaldehyde-sensitive and cytosolic paraformaldehyde-insensitive NADPH-diaphorase. The cytosolic NADPH-diaphorase activity coeluted with NOS activity. The activity of NOS was dependent on Ca2+ and NADPH and was inhibited by N(G)-nitro-L-arginine (L-NNA). Proteins purified by 2',5'-ADP affinity chromatography were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and migrated at 150, 60, 40, and 30 kDa. An antibody to mammalian NOS exclusively labeled the 60-kDa protein. Characterization of the cDNA of the corresponding 60-kDa NOS-immunoreactive protein revealed no sequence homology with any known NOS isoform. The recombinant protein exhibited Ca2+- and NADPH-dependent NOS activity, which was partially inhibited by EGTA and L-NNA. Histochemistry showed NADPH-diaphorase activity in discrete regions of the central and peripheral nervous system. About 60% of the NADPH-diaphorase-positive neurons colocalize with immunoreactive material detected by antibodies to mammalian NOS. Comparison of organs showed the highest NADPH-diaphorase activity in the nervous system, whereas moderate activity was present in muscle tissue, digestive tract, and gonads. Our study suggests the presence of NOS and a putative NOS-associated/regulating protein in mollusk nervous tissue.

Animals↗
PubMed1997

RCC1 and nuclear organization.

We have examined the effect of RCC1 function on the nuclear organization of pre-mRNA splicing factors and poly(A)+ RNA in the tsBN2 cells, a RCC1 temperature-sensitive mutant cell line. We have found that at 4-6 h after shifting cells from the permissive temperature (32.5 degrees C) to the restrictive temperature (39.5 degrees C), both small nuclear ribonucleoprotein particles and a general splicing factor SC35 reorganized into 4-10 large round clusters in the nucleus, as compared with the typical speckled distribution seen in cells at the permissive temperature. In situ hybridization to poly(A)+ RNA resulted in a similar pattern. Examination by double labeling demonstrated that the redistribution of splicing factors coincides with that of poly(A)+ RNA. Such changes in the nuclear organization of splicing factors and poly(A)+ RNA were not the result of the temperature shift or of chromatin condensation. Cellular transcription was not significantly altered in these cells and extracts made from both the permissive and restrictive temperature were splicing competent. Electron microscopic examination demonstrated that the large clusters containing both splicing factors and poly(A)+ RNA were fused interchromatin granule clusters. In addition, small electron-dense dot-like structures measuring approximately 80 nm in diameter were also observed, most of which are accumulated in enlarged interchromatin granule clusters in the nucleoplasm of RCC1- cells. In spite of the significant changes observed in the nucleoplasm, relatively little alteration was observed in nucleolar structure by both light and electron microscopic examination. The above observations suggest that the RCC1 protein directly or indirectly regulates the organization of splicing components and poly(A)+ RNA in the cell nucleus and that RCC1 may play a role in nuclear organization.

Animals↗
PubMed1997

Temporal association between serum gelsolin levels and clinical events in a patient with severe falciparum malaria.

Actin is present in high concentrations in most eukaryotic cells and can polymerize into filaments under physiological buffer conditions. As a result of tissue injury and cell lysis, large quantities of actin are released locally and may obstruct the downstream microvasculature, causing further damage to already injured organs. It has been postulated that this mechanism contributes to the development of the adult respiratory distress syndrome and to the diverse complications of falciparum malaria. Actin scavenging proteins--e.g., gelsolin--counteract the effects of extracellular actin, but the capacity of these plasma proteins can be overwhelmed by massive tissue injury. We examined the temporal relationship between serum levels of gelsolin (and tumor necrosis factor-alpha) and the clinical findings for a patient with severe falciparum malaria. The level of gelsolin decreased and then increased as the patient's status first worsened and then improved. We could not determine whether gelsolin served a biologically important function in this patient's recovery or was simply an epiphenomenon of disease activity. Gelsolin levels may be an early prognostic indicator in patients with a systemic inflammatory response syndrome. Moreover, the potential therapeutic role of recombinant human plasma gelsolin in patients with delayed organ dysfunction that commonly follows a self-limited initial insult merits investigation.

Adult↗
PubMed1997

Effect of electron beam irradiation on physical, physiochemical, and functional properties of liquid egg yolk during frozen storage.

Raw yolk of 1-d-old eggs was either subjected to linear electron beam irradiation at approximately 2.5 kGy dosage or not processed. Both irradiated and nonprocessed egg yolk samples were stored at -15 C after irradiation. Testing was conducted on 0, 1, 7, 15, 30, and 60 d of storage. Development of storage modulus (G') was delayed in irradiated samples after 7 d, which suggests that less structure was developed in irradiated egg yolk than in nonprocessed egg yolk during storage. Irradiated samples retained more soluble protein within the first 7 d and showed slightly improved emulsion capacity over that from nonprocessed samples. However, irradiated egg yolk was less bright than nonprocessed samples. No differences were observed in SDS-PAGE patterns of soluble proteins and delipidized low density lipoprotein (LDL). The LDL isolated from irradiated liquid egg yolk showed no difference in N-terminal amino acids compared to that of nonprocessed egg yolk, indicating no detectable cleavage of LDL. However, the denaturation temperature of irradiated samples at Day 0 shifted about 1 C lower than that of the nonprocessed sample. Results indicated that electron beam irradiation did not cause significant physical, chemical or functional changes of egg yolk, or cleavage of egg yolk protein. Therefore, electron beam irradiation could serve as a preservation method for liquid egg yolk.

Amino Acid Sequence↗
PubMed1997

Severe skin loss after meningococcal septicaemia: complications in treatment.

Meningococcal septicaemia can lead to purpura fulminans with subsequent full thickness skin loss and deep muscle damage. The case reports on two infants who recovered from such a severe episode are used to describe post-septicaemic procedures and complications encountered in nursing care, psychological support and rehabilitation, with the main focus on surgery. Skin grafting is complicated by contaminated and contracting wound areas. Extensive tissue necrosis required leg amputations. Cultured keratinocytes in one of the patients were found to be too vulnerable. It has still to be proven whether more radical early-stage fasciotomies can limit skin and muscle necrosis. Patients with meningococcal septicaemia are subject to a high number of complications that are optimally treated in a burns unit. These patients require up-to-date knowledge of constantly evolving treatment possibilities and a high-level collaboration of all medical fields involved.

Amputation, Surgical↗
PubMed1997

Evaluation of the ESP Culture System II for recovery of mycobacteria from blood specimens collected in isolator tubes.

The reliability of the ESP Culture System II (ESP II; AccuMed International, Westlake, Ohio), a continuously monitoring, nonradiometric mycobacterial culture system, for recovery of mycobacteria from sediments of blood collected in an Isolator tube was evaluated by comparing its performance to inoculation of the sediment onto Middlebrook 7H11/7H11 selective biplates. Of 1,704 blood specimens, 73 (4.3%) were positive for mycobacteria (68 Mycobacterium avium complex and 5 M. tuberculosis). Fifty-three specimens were positive by both methods; 13 were positive by ESP II only, and 7 were positive by Middlebrook agar only (chi square = 1.8; P > 0.05). The mean times to positivity were 15.6 days for ESP II and 19.0 days for Middlebrook agar (P < 0.01). The time to detection was the same for 13 specimens; ESP II was positive first for 33, and agar plates were positive first for 7. ESP II allowed recovery of more mycobacteria (90.4% of all isolates versus 82.2% for Middlebrook agar) from sediments of blood specimens collected in Isolator tubes, and it provided significantly faster detection than did Middlebrook plates.

Acquired Immunodeficiency Syndrome↗
PubMed1997

In vitro analysis of the E1A-homologous sequences of RIZ.

The RIZ (G3B/MTB-Zf) gene was first isolated based on its ability to bind to the retinoblastoma protein (Rb). An acidic, approximately 100-amino-acid region around the Rb-binding motif of RIZ has structural and antigenic similarity to the conserved sequences of the E1A viral oncogene. We show here that this region interacts specifically with the E1A-binding domain of Rb. This interaction could be disrupted by E1A or by a peptide of RIZ homologous to the CR2 motif of E1A which is involved in binding to Rb family proteins. Also like E1A, RIZ can form a ternary complex with Rb and E2F1. Despite this similarity to E1A, however, RIZ could not bind to the Rb family proteins p107 and p130 in vitro. The data show that the RIZ CR2 motif can mediate differential binding to Rb family proteins. We also mapped the shared antigenic determinant between RIZ and E1A to a conserved sequence, designated CE1, which is located in the C terminus of E1A. Unlike that of ETA, the CE1 motif of RIZ is located next to the CR2 motif. Despite this proximity, CE1 and CR2 appear to act independently. The data show similarities as well as differences between the homologous sequences of RIZ and E1A and contribute to an understanding of the biochemistry of these proteins.

Adenovirus E1A Proteins↗