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Biomedical subjects

F Huang

Publications and source records attributed to F Huang.

At least 55 records · Page 3Linked to original sources
PubMed2000

RNA-Catalyzed CoA, NAD, and FAD synthesis from phosphopantetheine, NMN, and FMN.

A novel in vitro selection method was developed to isolate RNA sequences with coenzyme-synthesizing activities. We used size-heterogeneous libraries containing randomized ribonucleotide sequences of four different lengths (30N, 60N, 100N, and 140N), all with 5'-ATP initiation. Two RNAs, CoES7 (30N) and CoES21 (60N), are able to catalyze the synthesis of three common coenzymes, CoA, NAD, and FAD, from their precursors, 4'-phosphopantetheine, NMN, and FMN, respectively. Both ribozymes require divalent manganese for activities. The results support the availability of these coenzymes in an RNA world, and point to a chemical explanation for the complex bipartite structures of many coenzymes.

Coenzyme A↗
PubMed2000

Interaction of EGF receptor and grb2 in living cells visualized by fluorescence resonance energy transfer (FRET) microscopy.

The interaction of activated epidermal growth factor receptor (EGFR) with the Src homology 2 (SH2) domain of the growth-factor-receptor binding protein Grb2 initiates signaling through Ras and mitogen-activated protein kinase (MAP kinase) [1,2]. Activation of EGFRs by ligand also triggers rapid endocytosis of EGF-receptor complexes. To analyze the spatiotemporal regulation of EGFR-Grb2 interactions in living cells, we have combined imaging microscopy with a modified method of measuring fluorescence resonance energy transfer (FRET) on a pixel-by-pixel basis using EGFR fused to cyan fluorescent protein (CFP) and Grb2 fused to yellow fluorescent protein (YFP). Efficient energy transfer between CFP and YFP should only occur if CFP and YFP are less than 50A apart, which requires direct interaction of the EGFR and Grb2 fused to these fluorescent moieties [3]. Stimulation by EGF resulted in the recruitment of Grb2-YFP to cellular compartments that contained EGFR-CFP and a large increase in FRET signal amplitude. In particular, FRET measurements indicated that activated EGFR-CFP interacted with Grb2-YFP in membrane ruffles and endosomes. These results demonstrate that signaling via EGFRs can occur in the endosomal compartment. The work also highlights the potential of FRET microscopy in the study of subcellular compartmentalization of protein-protein interactions in living cells.

Adaptor Proteins, Signal Transducing↗
PubMed2000

[Expression of bcl-2 in the normal endometrium and endometrium of adenomyosis].

Using immunohistochemical ABC staining, we detected the expression and role of bcl-2 in normal endometrium(n = 17) and eutopic and ectopic endometrium with adenomyosis(n = 16) during the menstrual cycle. The first result was that the expressions of bcl-2 in the eutopic endometrium were the same as the normal endometrium, showing predominantly in the glandular epithelial cells, and obviously cyclic changes throughout the menstrual cycle. This result suggests that these changes may be regulated by ovarian hormone and play an important role in the proliferation and physiologic death of normal endometrial glandular epithelial cells to regulate the menstrual cycle. Bcl-2 expression in the glandular cells of ectopic endometrium of adenomyosis had no cyclic change and bcl-2 staining had remained in the whole menstrual cycle. The second result suggests that the above mentioned phenomena may play an important role in the pathogenesis of adenomyosis.

Adult↗
PubMed2000

Epidermal growth factor is critical for intestinal adaptation following small bowel resection.

The loss of small intestinal mucosal surface area is a relatively common clinical situation seen in both the pediatric and adult population. The most frequent causes include mesenteric ischemia, trauma, inflammatory bowel disease, necrotizing enterocolitis, and volvulus. Following surgical resection, the remnant intestine compensates or adapts to the loss of native bowel by increasing its absorptive surface area and functional capacity. Unfortunately, many patients fail to adapt adequately, and are relegated to lifelong intravenous nutrition. Research into intestinal adaptation following small bowel resection (SBR) has evolved only recently from the gross and microscopic level to the biochemical and genetic level. As understanding of this process has increased, numerous therapeutic strategies to augment adaptation have been proposed. Epidermal growth factor (EGF) is an endogenous peptide that is secreted into the gastrointestinal tract and able to influence gut ontogeny, as well as mucosal healing. Early studies have demonstrated its ability to augment the adaptive process. Focusing on a murine model of massive intestinal loss, the morphological, structural, biochemical, and genetic changes that occur during the intestinal adaptive process will be reviewed. The role of EGF and its receptor as critical mediators of the adaptive process will be discussed. Additionally, the ability of EGF to augment intestinal proliferation and diminish programmed cell death (apoptosis) following SBR will be examined. Enhancing adaptation in a controlled manner may allow patients to transition off parenteral nutrition to enteral feeding and, thereby, normalize their lifestyle.

Adaptation, Physiological↗
PubMed2000

Functional significance of N- and C-terminus of the amino acid transporters EAAC1 and ASCT1: characterization of chimeric transporters.

To localize functionally significant domains in the amino acid transporters of mouse brain mEAAC1 and mASCT1, cRNA encoding for wild-type and chimeric transporters was injected into Xenopus oocytes. Activity of expressed transporters was investigated by measurements of uptake of 3H-labeled glutamate and serine and of glutamate- and serine-induced currents under voltage clamp. Though all transporters accept glutamate and serine as substrate, the central part of the protein (Ala94-Met418 of mEAAC1 and Ala119-Ile393 of mASCT1) determines substrate selectivity. The C-terminus rectifies the interaction with the respective substrate. A channel mode of the glutamate transporter can be activated by glutamate and serine, and the N- and C-termini of the mEAAC1 seem to be essential for the channel formation.

Amino Acid Sequence↗
PubMed2000

Epidermal growth factor alters the bax:bcl-w ratio following massive small bowel resection.

BACKGROUND: Following massive small bowel resection (SBR), the expression of bax and bcl-w is associated with increased enterocyte apoptosis. Epidermal growth factor (EGF) has been shown to enhance enterocyte proliferation and retard apoptosis in the adapting bowel. This study examined the effect of EGF on the expression of these bcl-2 family members during adaptation. MATERIALS AND METHODS: Mice (C57Bl/6; n = 38) underwent a 50% SBR or sham operation and then were randomized to receive twice-daily orogastric saline or EGF (50 microg/kg/day). After 3 days, the remnant ileum was removed, apoptotic index (No. apoptotic bodies/crypt) calculated, and expression of mRNA and protein for bax and bcl-w quantified. RESULTS: EGF prevented the expected increase in the apoptotic index after SBR and altered the ratio of bax to bcl-w in favor of cell survival. CONCLUSION: Following massive small bowel resection, EGF retards rates of enterocyte apoptosis and modifies the expression of bcl-2 family members. By decreasing bax and increasing bcl-w expression, the balance between pro- and anti-apoptotic genes is shifted in favor of cell survival. Alteration of bcl-2 family member expression may be an important mechanism by which EGF reduces the increased enterocyte apoptosis that occurs after massive small bowel resection.

Adaptation, Physiological↗
PubMed2000

Proteomics of Synechocystis sp. strain PCC 6803. Identification of periplasmic proteins in cells grown at low and high salt concentrations.

Periplasmic proteins isolated by cold osmotic shock of Synechocystis sp. PCC 6803 cells were identified using 2D PAGE, MS and genome analysis. Most of the periplasmic proteins represent 'hypothetical proteins' with unknown function. A number of proteases of different specificity, and several enzymes involved in cell wall biosynthesis were also found. In salt-adapted cells, six proteins were greatly enhanced and three proteins were newly induced. Most of the salt-enhanced proteins are involved in the alteration of cell wall structure of salt-adapted cells. The precursors of all 57 periplasmic proteins identified have a signal peptide; 47 of them contain a typical Sec-dependent signal peptide, whereas 10 contain a putative twin-arginine signal peptide.

Amino Acid Sequence↗
PubMed2000

Polymorphonuclear neutrophil (PMN) recruitment in a 2-front murine injury model: triage of PMNs to competing stimuli of recruitment.

BACKGROUND: Intensive care unit patients as a group have the highest rate of nosocomial infections, such as pneumonia, urinary tract infections, and wound infections. The triage of polymorphonuclear neutrophils (PMNs) during an acute inflammatory response was investigated to determine if the severity of injury or infection contributes to PMN delivery. METHODS: A murine cecal ligation and puncture-induced peritonitis model with polyvinyl sponge discs were used to collect the PMNs in the abdomen (primary site) and in the subcutaneous tissue of the dorsum (remote site). Eighty CD1 male mice--20 in each of 4 groups--were assigned to the following: cecal ligation and puncture (CLP), sham laparotomy with cecal manipulation (CM), polyvinyl sponge placement in the abdomen and back only (SP), and sponge placement in the back alone (CON [control]). After 24 hours, the sponges were harvested, and the PMNs were collected and counted on a hemocytometer. RESULTS: These data, reported as mean PMN cells x 10(5) +/- SEM, demonstrated that back sponges contained significantly fewer PMNs in the CLP group (3.29 +/- 1.1) than in the CM group (7.77 +/- 1.61, P = .04), the SP group (8.69 +/- 1.67, P = .01), and the CON group (11.04 +/- 1.91, P < .001). CONCLUSIONS: These results demonstrate that PMN delivery to sites of secondary injury are inversely correlated to the severity of the primary injury or peritonitis.

Animals↗
PubMed2000

Bax is required for increased enterocyte apoptosis after massive small bowel resection.

BACKGROUND: Massive small bowel resection (SBR) increases rates of both enterocyte proliferation and apoptosis. Previous studies have demonstrated increased intestinal expression of proapoptotic bax mRNA and protein, as well as the appearance of an 18-kd bax cleavage product within 12 hours of SBR. This study tested the hypothesis that bax is required for postresection increases in enterocyte apoptosis. METHODS: Male bax-null and C57Bl/6 (control) mice underwent either a 50% proximal SBR or sham operation. After 3 days, the remnant ileum was harvested and weighed. Apoptotic indexes, proliferation indexes, villus heights, and crypt depths were determined. RESULTS: The usual adaptive increases in ileal wet weight, crypt depth, and rate of proliferation occurred in both the control and bax-null mice. Resection significantly increased the rate of apoptosis in the control mice; however, it failed to alter the apoptotic index in the bax-null mice. CONCLUSIONS: Bax is necessary for the increase in apoptosis that occurs after SBR, but its absence has no significant effect on short-term adaptation. These findings suggest that enterocyte proliferation and apoptosis are differentially regulated during intestinal adaptation.

Animals↗
PubMed2000

Design, synthesis, and pharmacological evaluation of soft glycopyrrolate and its analog.

Glycopyrrolate is a quaternary anticholinergic drug. Like for other anticholinergics, the usefulness of this agent is limited by its side effects. In this study, based on the structure of glycopyrrolate, we designed a soft drug, methoxycarbonylphenyl-cyclopentylacetoxy-N,N-dimethyl-3-p yrrolidinium methyl sulfate (SG), and its analog, methoxycarbonylphenylcyclopentyl-acetoxyethyl-N,N,N-trimethylammon ium methyl sulfate (SGA). These soft drugs are expected to be locally active, but systemically inactive in order to increase therapeutic index. SG and SGA were synthesized by (i) carboxylation of methyl phenylcyclopentylacetate, (ii) esterification with N-methyl-3-pyrrolidinol (for SG) or 2-chloro-N,N-dimethylaminoethane (for SGA), and (iii) quarternization with dimethyl sulfate. Receptor binding studies demonstrate that SG has muscarinic subtype selectivity (m3/m2). Guinea pig ileum pA2 assay indicates that activity of SG is moderate, and SG is about ten times more potent than SGA. The in vivo characterization of SG and SGA, both in mydriasis tests and in prevention of carbachol induced bradycardia, supported its soft nature. Applying SG or SGA into rabbit eyes, the dilation of the contralateral (water-treated) pupils was not observed. Glycopyrrolate application, however, caused dilation of the contralateral pupil, indicating a systemic effect of this drug. Cardiac studies were carried out by evaluating the protective effect of soft anticholinergics against carbachol induced bradycardia. The results indicate that SG and SGA were as potent as atropine-MeBr in preventing carbachol induced bradycardia in the rat; however, their durations of action were significantly shorter. In conclusion, the newly synthesized SG and SGA showed soft nature in the body. They are anticholinergics with subtype selectivity and moderate potency, and can be used as topical antiperspirants.

Administration, Topical↗
PubMed2000

[Expression and roles of hemoglobin gene in Bacillus subtilis].

Hemoglobin of the Gram-negative bacterium Vitreoscilla can bind oxygen strongly and reduce the oxygen requirement of the bacterium. A recombinant plasmid pAV was constructed by inserting the hemoglobin gene (Vgb) to the downstream of the promoter of beta-lactase gene of the B. subtilis plasmid pAK4. The plasmid pAV was transferred into strain DB104, G331 (a subtilisin-producing B. subtilis) and B53 (a xylanase-producing B. subtilis). The subclones and transfer of the Vgb gene into pAK4 were detected and confirmed by Dot blotting and electrophoresis analysis. The expression of homoglobin was measured by recording CO-difference spectra after bubbling CO into the sample cuvette. The production of subtilisin and xylanase was increased in the fermentation of the Vgb-expressing strains. These results provided a new way to reduce the oxygen requirement and to increase the biomass production in the fermentation industry.

Bacillus subtilis↗
PubMed2000

[The cloning and expression of soluble HLA-B27 gene].

OBJECTIVE: To clone and express the soluble HLA-B27 (sB27) gene in human B lymphoid cell line. METHODS: Soluble B27 cDNA was constructed by 3 consecutive rounds of PCR and then cloned into the RSV5neo vector. The construct was transfected into C1R cells. RESULTS: Restriction enzyme digestion and DNA sequencing confirmed that the construct was the HLA-B27 gene lacking exon 5 which encodes the transmembrane domain of HLA molecule. The expression of aHLA-B27 was verified successfully in the culture supernatant of C1R cells. The level of sHLA-B27 changed with variable culture conditions, such as temperature and concentration of fetal calf serum. CONCLUSION: The sHLA-B27 molecules can be generated by alternative splicing of HLA-B27 pre-mRNA. Our construct provide a useful model for studying the effect of environmental factors such as bacterial infections and cytokine stimulation on the expression of soluble HLA-B27 molecule. It will also provide clues for the role of HLA-B27 molecule in the pathogenesis of spondyloarthropathies.

Cell Line↗
PubMed2000

[Detection and significance of plasminogen activator inhibitor in synovial tissue, synovial fluid and plasma from patients with rheumatoid arthritis].

OBJECTIVE: To study the distribution and expression of type-1 plasminogen activator inhibitor (PAI-1) and type-2 plasminogen activator inhibitor (PAI-2) in synovial tissue from rheumatoid arthritis(RA) and measure the antigen levels and activity in synovial fluid and plasma of patients with RA. METHODS: Immunohistochemical analysis was used to detect PAI-1 and PAI-2 expression and distribution in synovial tissue from 24 RA patients, 18 osteoarthritis (OA) patients and 6 normal subjects. PAI-1 and PAI-2 antigen concentration and activity were determined with ELISA sandwich method. RESULTS: In RA patients, positive staining of PAI-1 and PAI-2 was seen respectively in all the 24 cases and 8 of the 24 cases; positive expression was distributed mainly in the synovial lining area. In OA patients, positive staining of PAI-1 was detected in 8 cases and its positive distribution was similar to that in RA. No PAI-2 positive staining was seen in all the OA cases. In 6 normal subjects with normal synovial tissue, the staining was negative. The concentration and activity of PAI-1 in RA synovial fluid(SF) were significantly higher than those in the plasma(P < 0.001 and P < 0.05). The concentration and activity of PAI-1 in the plasma of RA were also much higher than those in the plasma of OA(P < 0.05 and P < 0.0001) and healthy subjects(P < 0.0001 and P < 0.001). The concentration and activity of PAI-1 in SF and plasma of RA correlated positively. CONCLUSION: The up-regulated expression of PAI-1 and PAI-2 and the concentration and activity of PAI-1 in SF and plasma were significantly higher in RA than those in OA and healthy subjects, suggesting PAI especially PAI-1 may play an important role in the pathogenesis of RA.

Adolescent↗
PubMed2000

[Study on the application of random amplified polymorphic DNA in Yersinia pestis genotyping].

OBJECTIVE: To study the type of 103 Y. pestis strains that isolated from different plague foci and different ecological types. METHOD: Random amplified polymorphic DNA (RAPD) was used. RESULTS: Y. pestis were divided into two RAPD types: most strains that isolated from elsewhere in the country belonged to RAPD-1 type, while most strains that isolated from Qinghai province were RAPD-2 type. CONCLUSION: The genome structures of different ecotype Y. pestis were different providing the foundation of further research and prevention of plague.

Animals↗
PubMed2000

[Effect of sodium fluoride on bone turnover and bone loss of vertebrae and tibia in ovariectomized rats].

OBJECTIVE: To investigate the effect of sodium fluoride on bone turnover and bone loss of vertebra and tibia of ovariectomized rats. METHODS: 34 female Wistar rats, 16 weeks old, were divided into 3 groups: sham-ovariectomy (CON), bilateral ovariectomy (OVX) and both OVX and NaF-treatment groups (OVX + NaF, 1.0 mg/kg BW). All of the rats were sacrificed 12 weeks after the treatment. Serum was collected for the analysis of estradiol, calcium, phosphorum and alkaline phosphotase. Temur was used for the analysis of calcium content. Tibiae and the first lumbar vertebral bodies were decalcified for histomorphometry. RESULTS: After treatment with NaF, bone resorption was not inhibited, but bone formation was significantly increased. The trabecular bone volume of vertebrae (18.73% +/- 3.04%) and tibiae (14.30% +/- 5.87%) was significantly increased in comparing with of OVX rats (15.07% +/- 2.45% and 8.81% +/- 2.60%, P < 0.05), but it was markedly lower than that of CON rats (22.44% +/- 1.82% and 24.87% +/- 4.02%, P < 0.05 and P < 0.01). CONCLUSIONS: NaF could not decrease bone turnover and it, has only a partial protective effect against bone loss of either vertebra or tibia.

Animals↗
PubMed2000

[An experimental study of antibiotic -- induced endotoxin release in Pseudomonas aeruginosa bacteremia inburned rats].

OBJECTIVE: To assess the intensity of endotoxin release in Pseudomonas aeruginosa challenged burned rats after the administration of various antibiotics. METHODS: Rats were inflicted with 30% TBSA burn, and they were challenged with Pseudomonas aeruginosa (PA103). After the administration of different beta lactam antibiotics, serum endotoxin level and blood bacterial count were determined. RESULTS: All the antibiotics used were effective in eradicating the bacteria with concomitant release of endotoxin in varying amounts. It was found that Imipenem released the least amount of endotoxin, followed in order by Cefoperazone, Ceftazidime, and Cefotxime. CONCLUSIONS: Different antibiotics possessed varying capacity of inducing endotoxin release from PA, and the amount released did not bear any relation with the bactericidal capability of the antibiotics.

Animals↗
PubMed2000

[Evaluation of competence for serve a sentence].

In order to explore the factors influencing the evaluation of competence for serve a sentence, 102 cases of forensic psychiatric expertise were reviewed. A questionnaire of "scale of adaptability to punishment circumstance" was designed to investigate these cases. The results showed that the patients of psychotic mental disorders and the patients with history of mental disorders have a relatively high rate of non-competence of serving sentences, and that they can not adapt theirself to punishment circumstance.

Adolescent↗