Biomedical subjects

F Jiang

Publications and source records attributed to F Jiang.

At least 127 records · Page 7Linked to original sources

PubMed1996

Somatostatin stimulates BKCa channels in rat pituitary tumor cells through lipoxygenase metabolites of arachidonic acid.

The stimulation of large-conductance, calcium-activated (BK) potassium channels by somatostatin through protein dephosphorylation in rat pituitary tumor cells (White et al., Nature 351, 570-573, 1991) is blocked by drugs that interfere with arachidonic acid release by phospholipase A2 and metabolism by 5-lip-oxygenase. In contrast, higher concentrations of the same drugs had no effect on BK channel gating in cell-free patches, on the inhibition of adenylyl cyclase by somatostatin, or on the stimulation of BK channels by protein dephosphorylation through a cGMP-dependent pathway (White et al., Nature 361, 263-266, 1993). Exogenous arachidonic acid (1-20 muM) stimulated BK channel activity through protein dephosphorylation as effectively as somatostatin and was also blocked by inhibitors of lipoxygenases but not by inhibitors of phospholipase A2. These results support the hypothesis that lipoxygenase metabolites of arachidonic acid are second messengers linking pertussis toxin sensitive G-proteins to protein phosphatases regulating potassium channel activity (Armstrong and White, Trends Neurosci. 15, 403-408, 1992).

Adenosine Triphosphate↗

PubMed1996

Steroidal glycosides from Tribulus terrestris.

In addition to hecogenin 3-O-beta-D-glucopyranosyl(1--> 4)-beta-D-galactopyranoside, two new steroidal saponins were isolated from the aerial parts of Tribulus terrestris L. On the basis of chemical and spectroscopic evidence, especially 2D NMR spectroscopic techniques, the structures of the new saponins were established as 26-O-beta-D-glucopyranosyl-3-O-[-beta-D-xylopyranosyl(1--> 3)--beta-D-galactopyranosyl(1-->2)--beta-D-glucopyranosyl (1--> 4)-beta-D-glucopyranosyl]-5 alpha-furost-20(22)-en-12-one-3 beta,26-diol and 26-O-beta-D-glucopyranosyl-3-O-[{beta-D-xylopyranosyl (1-->3)--beta-D-galactopyranosyl(1-->2)--beta-D-glucopyranosyl(1 -->4)-beta-D-glucopyranosyl]-5 alpha-furostan-12-one-3 beta,22,26-triol.

Carbohydrate Conformation↗

PubMed1996

Skull base cerebrospinal fluid leakage control with a fibrin-based composite tissue adhesive.

Cerebrospinal fluid (CSF) leaks can be responsible for significant patient morbidity and mortality. While the majority of leaks induced after head trauma will seal without intervention, spontaneous or surgically-induced leaks often require operative repair. Many modifications on standard surgical technique are available for repair of CSF fistulae, but none assures adequate closure. We have studied the efficacy of a novel fibrin-based composite tissue adhesive (CTA) for closure of experimentally-induced CSF leaks in rats. Fistulae were created in two groups of animals. Two weeks after creation of the leaks, the animals were sacrificed and analyzed for persistence of leak. A 58% leakage rate was noted in the control group (n = 12), and no leaks were noted in the experimental group closed after application of CTA to the surgical defect followed by skin closure (n = 11). Comparing the control group to the experimental group, results were statistically significant (p = 0.015). These data suggest that CTA may be effective as an adjunct for the closure of CSF fistulae.

Journal Article↗

PubMed1996

Photodynamic therapy of human glioma (U87) in the nude rat.

We measured the response of normal brain and the human U87 glioma implanted in the brain of rats (n = 65) to photodynamic therapy (PDT) using Photofrin as the sensitizer. Normal brain and U87 tumor implanted within brain of athymic (nude) rats were subjected to PDT (12.5 mg/kg of Photofrin) at increasing optical energy doses (35 J/cm2, 140 J/cm2, 280 J/cm2) of 632 nm light. Photofrin concentration in tumor, brain adjacent to tumor and normal brain were measured in a separate population of rats. Twenty-four hours after PDT, the brains were removed, sectioned, stained with hematoxylin and eosin (H&E), and the volumes of the PDT-induced lesion measured. Photofrin concentration in tumor greatly exceeded that of normal brain and brain adjacent to tumor (> 20x). Both normal brain and U87 tumor exhibited superficial tissue damage with PDT at 35 J/cm2. However, both normal and tumor-implanted brain exhibited tissue damage with increasing optical dose. A heterogeneous pattern of pannecrosis along with a uniform volume of pannecrosis was detected in the tumor. In contrast, normal brain exhibited a uniform sharply demarcated volume of necrosis. Our data indicate that the U87 human brain tumor model and the normal brain in the athymic rat are sensitive to PDT and Photofrin with an optical dose-dependent response to treatment.

Animals↗

PubMed1996

Sensitivity of 9L gliosarcomas to photodynamic therapy.

Photodynamic therapy (PDT) has been used clinically for the treatment of malignant brain gliomas. However, the efficacy of this treatment to date has remained equivocal. This study focused on determining the sensitivity of 9L glio sarcoma in Fischer 344 rats to PDT with increasing doses of 632 nm light and making a comparison of the responses of normal and tumor tissue in the brain at these doses. This sensitivity was then correlated with the concentrations of Photoforin present in these tissues at the time of treatment. Our study indicates that the level of Photofrin in the tumor was 13 times that present in normal brain 48 h after injection. However, this selective localization of the photosensitizer was not reflected in a selective tissue response to PDT. There was minimal tumor response to a dose of 35 J cm-2, which has been reported previously to cause necrosis to the normal brain. Increasing energy dose levels resulted in an increased tumor response to PDT; however, normal tissue remained more sensitive than tumor tissue at all energy dose levels examined. These data indicate that, although Photofrin is retained to a significantly higher degree in the tumor than in the normal brain tissue, the normal brain is more sensitive than the tumor to PDT under the conditions outlined in this study.

Animals↗

PubMed1996

[Comparison of the three methods for estimating the dry-weight of hemodialysis patients].

In order to find the best method for estimating the dry-weight of hemodialysis (HD) patients, we compared the three methods used, i.e. bioelectrical resistivity (rho), plasma cGMP (cGMP) and bromide (Br) methods. The results showed that the extracellular fluid volume per unit body mass (EFV/mass) determined with rho was negatively correlated with that determined with Br. (r = -0.7601 for normal controls and -0.5293 for HD patients, P < 0.05). However, plasma cGMP concentration was neither correlated with EFV/mass (r = 0.3724 for normal control and 0.2538 for HD patients, P > 0.05) nor with rho (r = 0.5210 for normal controls and 0.2106 for HD patients, P > 0.05). These results suggest that the bioelectrical resistivity dry-weight method is more accurate than cGMP method and moreover it is easier to perform than the NaBr method.

Adult↗

PubMed1996

[A study of 5-fluorouracil on bovine trabecular meshwork cells in vitro].

OBJECTIVE: To determine whether the clinical use of 5-fluorouracil (5-FU) may have any toxic effects on trabecular meshwork cells. METHODS: Bovine trabecular meshwork (BTM) cells were cultured in vitro. The effects of 5-FU on BTM cells concerning cellular morphology, ultrastructure, vitality and phagocytosis were observed. RESULT: The safe dosage of 5-FU on BTM cell was 1 x 10-6g.ml-1. CONCLUSION: Based on the pharmacokinetic data in the rabbit anterior chamber, it is suggested that the 5-FU dosage of conventional use cause no injury to human trabecular meshwork cells.

Animals↗

PubMed1996

[Pharmacognostical study on the Chinese drug biejia].

The Chinese drug Biejia is taken from a variety of animals. In this paper, 3 kinds of Biejia from different genera have been studied in their pharmacognostical characteristics and microproperties. A key has been complied based on the experimental results.

Animals↗

PubMed1995

Cloning, sequencing, and regulation of the glutathione reductase gene from the cyanobacterium Anabaena PCC 7120.

Glutathione reductase (GR) was purified from the cyanobacterium Anabaena PCC 7120. A 3-kilobase genomic DNA fragment containing the coding sequence for the GR gene (gor) was identified and cloned by polymerase chain reaction based on sequences of selected peptides isolated from proteolyzed GR. The coding sequence encompassing 458 amino acid residues, as well as 360 base pairs of the 5'-flanking region and 430 base pairs of the 3'-flanking region, were determined. Genomic Southern analysis indicates that gor is a single-copy gene. A gor antisense RNA probe hybridized with a 1.4-kilobase transcript, suggesting that the gene is not part of an operon including additional genes. The deduced GR amino acid sequence shows 41 to 48% identity with those of human, Escherichia coli, Pseudomonas aeruginosa, pea, and Arabidopsis thaliana GR. The coding sequence of GR was overexpressed in a GR-deficient E. coli strain, SG5, and the recombinant protein was purified. Anabaena GR is NADPH-linked, but a Lys residue replaces an Arg residue involved in NADPH binding in GR from other species. In addition, Anabaena GR carries the GXGXXG "fingerprint" motif which otherwise characterizes NAD(H)-dependent enzymes. These differences may contribute to the lack of affinity for 2',5'-ADP-Sepharose 4B of Anabaena GR. Three E. coli-type promoter sequences and a BifA/NtcA binding motif were found upstream of the open reading frame. The middle and the proximal promoters were shown to be active. However, the use of the middle promoter was dependent on the nitrogen source in the culture medium. Both GR activity and GR protein concentration increased in ammonium grown cultures in which both the middle and proximal promoters were used for transcriptional initiation. The BifA/NtcA-binding site overlaps the middle promoter sequence and may thus be involved in regulation of differential transcription.

Amino Acid Sequence↗

PubMed1995

Cu(II) coordination in arthropod and mollusk green half-methemocyanins analyzed by electron spin-echo envelope modulation spectroscopy.

Hemocyanin (Hc) is a dinuclear copper protein that binds oxygen reversibly. The structure of the Cu(II) site in a derivative of hemocyanin known as green half-met (GHM) has been analyzed using the pulsed EPR technique of electron spin-echo envelope modulation (ESEEM) spectroscopy. The derivative, prepared by treating the native protein with nitrite at low pH, contains a mixed-valent binuclear copper center. It was shown through chemical assays and the ligand exchange reaction products identified by EPR spectroscopy to contain a nitrite ligand bound to Cu(II). The ESEEM spectra of green half-methemocyanins from mollusks and arthropods indicated that three imidazole ligands are coordinated to Cu(II). Therefore, a tetragonal N3O ligand structure (O is an oxygen of nitrite) is proposed. For GHM Hc from the mollusks Octopus vulgaris and Rapana thomasiana, the isotropic nitrogen nuclear hyperfine coupling constant, aiso, for the N delta (or remote) nitrogen of two imidazoles was approximately 1.4 MHz, while for the third, aiso congruent to 2.2 MHz. The difference between the two weaker nitrogens and the single, more strongly coupled nitrogen was smaller by 0.2 MHz in the GHM Hcs from the arthropods Carcinus maenas, Homarus americanus and Panulirus interruptus. The nitrogen nuclear quadrupole coupling constants and asymmetry parameters, e2Qq and eta, for the N delta nitrogens in nearly all cases were near 1.4 MHz and 0.8, respectively, although Rapana thomasiana GHM Hc exhibited a reduction in eta that may indicate weaker hydrogen bonding in the active site of this protein. The g and ACu (copper nuclear hyperfine coupling) values for the derivatives, and the finding of three similar nuclear hyperfine coupling constants for the N delta sites of imidazole ligands, when considered with the orientation-specific information obtained using angle-selection methods for simulation of ESEEM spectra, suggest a distorted tetragonal Cu(II) structure in which three imidazoles and a nitrite ligand are bound near the equatorial plane. The finding that the two molluscan GHM Hcs exhibit differences associated with the remote nitrogen of imidazoles bound to Cu(II) may be related to a structural variability in the active sites of these proteins not found in the arthropodan GHM Hcs examined.

Animals↗

PubMed1995

Comparison of the induction of rat glutathione S-transferase and fatty acid ethyl ester synthase activities.

Fatty acid ethyl esters (FAEE) are formed following the administration of ethanol and have previously been associated with toxicological effects in animals and humans. It has been suggested that the enzyme responsible, FAEE synthase, has both structural and catalytic properties very similar to a glutathione S-transferase (GST). Since GSTs are inducible, their induction could be associated with enhanced FAEE formation and toxicity. In the present study, rats were administered beta-naphthoflavone, phenobarbital, ethanol, or Aroclor 1254, and hepatic FAEE synthase and GST activities were measured. beta-Naphthoflavone and ethanol did not induce either activity. Phenobarbital increased GST activity in the liver but not in lung or pancreas. Only Aroclor 1254, which increased GST activity in liver and pancreas, increased FAEE synthase activity and then only in the liver. Thus, in comparison with GST activity, FAEE synthase activity is very limited in its ability to be induced.

Acyltransferases↗

PubMed1995

A new digoxin immunoassay substantially free of interference by digoxin immunoreactive factor.

We have evaluated the new Roche digoxin "On Line" procedure for use in a pediatric population with particular interest in the potential for interference by digoxin-like immunoreactive factor (DLIF). An initial study comparing digoxin values obtained with the new Roche procedure with determinations on an Abbott TDx, American Dade Stratus, and COBAS-FARA using Microgenics Cedia reagents, found good correlations with these established methods. The Roche method was suitably precise and utilized either serum or plasma. Interference by DLIF was assessed by analyzing specimens from patients not receiving digoxin but likely to contain DLIF, with the argument that non-zero values represent cross-reactivity of anti-digoxin antibodies with DLIF endogenous to these specimens. When specimens from neonates, women with second/third trimester pregnancies, and patients with renal and liver failure were assayed with the Roche, Stratus, and TDx methods, all three methods measured DLIF in some specimens, but the Roche method possessed the lowest overall DLIF interference. The modest extent of DLIF interference and the requirement of a small amount of specimen make the Roche method superior in monitoring digoxin in a pediatric population.

Digoxin↗

PubMed1995

[Preliminary survey on the traditional Chinese drug: shell of abalone or sea-ear].

According to an on-site survey of the commercial medicinal materials in China, it is demonstrated that the shells of abalone or sea-ear consist of nine types. Their original animals are Haliotios diversicolor, H. discus hannai, H. ovina, H. asinia, H. ruber, H. laevigata, H. semistrata, H. midae and H. cracherodii. Three of these types namely, H. semistrata, H. midae and H. cracherodii are not included in the Chinese Pharmacopeia. Furthermore, most of the shells of abalone or sea-ear presently on market are Haliotios ruber and H. discus hannai.

Animals↗

PubMed1994

Overexpression and characterization of recombinant human fusion protein IL-6/IL-2 (CH925).

An expression vector encoding the human recombinant fusion protein interleukin 6/interleukin 2 (IL-6/IL-2) was constructed. When a flexible linker had been synthesized and ligated with the IL-2 gene fragment by polymerase chain reaction (PCR) amplification, the IL-6 gene fragment was unidirectionally inserted into the upstream of the linker-IL-2 sequence. The molecule of the IL-6-linker-IL-2 fusion gene named E. coli DH5 alpha/pfIL-6/2 was cloned and identified by DNA sequencing. The expressed protein named as CH925 showed a strong band on SDS-PAGE and amounted to 32% of total cell protein, and its estimated molecular weight was about 37 kDa. The fusion protein purified by gel filtration and reversed-phase HPLC showed as almost homogeneous. CH925 possesses both IL-2 and IL-6 activities when assayed by CTLL2- and 7TD1-dependent cell lines, respectively. The specific activity of IL-2 was 2.1 x 10(6) U/mg while that of IL-6 was 2.3 x 10(8) U/mg. Our studies exhibited that CH925 exerted a significant augmentative effect on the growth of erythroid colony forming units (CFU-E), and synergized with erythropoietin (EPO) and/or IL-3 in a dose-dependent way. Our experimental results also showed CH925 at a low dose causing active lymphokine-activated killer (LAK) cell proliferation more vigorous than IL-2 and/or IL-6 (p < 0.001). CH925 is a novel fusion protein, being neither IL-6 nor IL-2, more potent than IL-2 and/or IL-6 and causing non-IL-2 and non-IL-6 functions of strong EPO-like and mild IL-3-like effects on erythroid progenitor cell growth. There is a potential for efficacious clinical application of CH925.

Base Sequence↗

PubMed1994

Hippocampal stimulation of fornical-lesioned rats improves working memory.

Intrinsic rhythmic electrical activity in the brain, such as the hippocampal theta rhythm, might serve important roles in normal cognition. Lesions to the medial septal nuclei, or to the fimbria/fornix, disrupt the hippocampal theta rhythm and lead to memory impairment. We have superimposed an artificial stimulating rhythm to the hippocampus of rats with prior lesion of the fornix, during testing in the Morris water maze. This intervention improves performance in a test of working memory, and lends support to the view that intrinsic rhythmic activity may play an important role in normal physiology, and in certain disease states.

Analysis of Variance↗

PubMed1994

[Study on risk factors of 292 pregnant women infected with HCMV].

This paper is to determine the risk factors of reactivation by HCMV during pregnancy for improving child birth and bringing-up. A total of 292 paired sera were collected from mothers and their infants in Shanghai and were tested for IgG and IgM by ELISA. The positive rates of HCMV IgG and IgM were 98.97%, 96.97% and 3.77%, 1.71%, respectively in mothers and infants. The rate of IgM was 1.49% in infants whose mothers' education were above the high school level, whereas it was 4.17% whose mothers' educational degree was lower than that grade, and the relative ratio (RR) was 2.8. The number of previous pregnancies were closely associated with the positive rate of IgM. In infants born to mothers at first pregnancy, the positive rate was 1.96%, whereas in infants born to mothers at third pregnancy it increased to 3.70%, RR was 1.89. In pregnant women who were known to have postmortem or premature deliveries before the positive rate was 9.09%, whereas it was 2.53% in pregnant women at first pregnancy, the RR was 3.59. The rates of their infants were 3.03% and 1.90%, respectively, the RR was 1.59. The frequency of IgM antibody in 292 sera of mothers was correlated with that in their infants. It showed that HCMV might be transmitted from mother to fetus.

Adult↗

PubMed1993

Two crystal structures of a potently sweet protein. Natural monellin at 2.75 A resolution and single-chain monellin at 1.7 A resolution.

Two refined structures of the sweet-tasting protein monellin are presented. The structure of natural monellin has been refined at 2.75 A resolution. The final model consists of four monellin molecules in the asymmetric unit, encompassing 3136 non-hydrogen atoms. The crystallographic R-factor is 0.193 for the 8853 reflections between 6.0 A and 2.75 A resolution, and the root-mean-square deviations from ideality are 0.017 A for bond lengths and 3.6 degrees for bond angles. The refined structure generally confirms, with some difference in detail, the initial backbone model of monellin that was based on 3.0 A resolution data. Single-chain monellin (scm) was genetically engineered by fusing the two chains of monellin into a single 94-residue polypeptide. Using the refined monellin coordinates as a search model, the crystal structure of scm has been solved with the techniques of molecular replacement, and has been refined against data to 1.7 A resolution. The final model consists of two scm molecules per asymmetric unit, and includes 137 bound water molecules. The crystallographic R-factor for this model is 0.174 for the 15,053 reflections (magnitude of FO magnitude of > 2 sigma (FO)) between 6.0 A and 1.7 A resolution. The root-mean-square deviations from ideal bond lengths and angles are 0.015 A and 2.86 degrees, respectively, and the average coordinate error is approximately 0.2 A, as estimated from a Luzzati plot. The error in the model was also estimated by comparing the two molecules in the asymmetric unit. The most significant differences between the two molecules occur in loop regions and at the C terminus of the protein, and are generally correlated to differences in crystal packing contacts. Linking the two chains of monellin has not substantially altered the structure beyond the region immediately surrounding the new peptide bond. Like natural monellin, the conformation of scm is dominated by a 17-residue alpha-helix folded into the concave side of a twisted, five-strand anti-parallel beta-sheet. We expect that the availability of a high-resolution structure of scm, along with the convenience of producing site-specific mutants of this protein, will make scm a good model with which to probe the structural basis of sweetness.

Amino Acid Sequence↗

PubMed1993

Effects of ethanol ingestion on glucose transporter-1 protein and mRNA levels in rat brain.

In the normal adult brain, glucose provides 90% of the energy requirement, as well as substrate for nucleic acid and lipid synthesis. We have previously observed that ethanol impairs hexose uptake by rat astrocytes in culture. In the present study, male Sprague-Dawley rats, 200-250 g, were fed liquid diet in which 36% of the calories were derived from ethanol (EF) for 4 weeks. Controls were fed ad libitum (AF) or pair-fed (PF) an equicaloric diet without ethanol. Blood glucose levels did not differ between the groups at the time of study. Glucose transport by brain plasma membranes was characterized by cytochalasin B binding and showed a slight increase in transporter number (mean +/- SEM of 4 experiments = 76.4 +/- 2.5 pmoles/mg protein in EF vs. 69.5 +/- 1.0 in PF) with no change in affinity (1.8 +/- 0.1 nM-1 in EF and 1.6 +/- 0.1 in PF). Glucose transporter, GLUT-1, was increased on Western blots. In contrast, Northern analysis of cortical tissue, using a rat brain glucose transporter cDNA insert (1.59 kb Bgl II fragment of pSPGT-1), showed a 23 to 35% decrease in steady-state levels of glucose transporter mRNA. GLUT-1 mRNA, localized in brain sections by in situ hybridization histochemistry, showed marked reductions in choroid plexus and hippocampus following ethanol treatment. Ethanol appears to have multiple effects on brain GLUT-1.

Alcoholism↗