Biomedical subjects

J Song

Publications and source records attributed to J Song.

At least 253 records · Page 14Linked to original sources

PubMed1998

[A modification to traditional combined approach tympanoplasty].

A modified method of traditional combined approach tympanoplasty (CAT) was performed on for 86 cases (89 ears). The patients were followed-up on for 18-50 months. No recurrent cholesteatoma or cochlear hearing impairments were found, and all the tympanic membranes had healed. The results of pure tone hearing tests showed that 66 ears (74%) had partial hearing (higher than 30 dB HL level), 56 ears (63%) had a small gap between BC and AC (< 10 dB HL), 10 ears (11%) had no hearing improvement. The total effective rate (the pure tone hearing improved more than 10 dB HL after operation) was 89% (79 ears). The clinical application of this kind of modified operation method had shown its important significance in thoroughly removing the diseased tissue, in preventing recurrent or residual cholesteatoma, in substantial hearing reconstruction and in improving the function of tympanum. Also the indication of combined approach tympanoplasty has been extended.

Adolescent↗

PubMed1998

[The clinicopathological study on 41 cases of cardiac tumors].

OBJECTIVE: To analyze the relation between the pathological changes and the prognosis of cardiac tumors through the clinicopathological study on 41 cases of cardiac tumors. METHODS: The study was carried out by using the common and special histochemical stainings. RESULTS: 39(95.1%) tumors were benign, including myxoma, fibroma, and rhabdomyoma; while 2(4.9%) tumors were malignant, including neurofibrosarcoma and malignant mesothelioma. In the myxomas group, 75% patients were female, 91.7% tumors existed in the left atrium. CONCLUSIONS: The results of the clinicopathological study showed that the cardiac tumors were quite different from the tumors in the other sites, i.e. even benign ones could cause fatal hemodynamic disturbance, hence early diagnosis and early operation are necessary. The prognosis of the malignant tumors is worst.

Female↗

PubMed1998

Sma I, Hha I, Msp I and Rsa I restriction fragment length polymorphisms in the von Willebrand factor gene of Chinese population.

OBJECTIVE: To study Sma I, Hha I, Msp I and Rsa I restriction fragment length polymorphisms in vWF gene of Chinese population. METHODS: The vWF gene from 52 unrelated individuals of Han Nationality, 44 of Yi tribe, 42 of Dai tribe was analyzed by polymerase chain reaction and digestion of the endonucleases of Sma I, Hha I, Msp I and Rsa I. RESULTS: The allele frequencies were 0.38:0.62 for Sma I+:Sma I- and 0.38:0.62 for Hha I+:Hha I-; 0.20:0.80 for Msp I+:Msp I-; 0.93:0.07 for Rsa I+:Rsa I- in Chinese Han population. The theoretical heterozygous rates were 0.46, 0.46, 0.36 and 0.13 of these polymorphisms, respectively. The allele frequencies were 0.43:0.57 for Sma I+:Sma I- and 0.43:0.57 for Hha I+:Hha I-, 0.26:0.74 for Msp I+:Msp- in Yi tribe and 0.36:0.64 for Sma I+:Sma I- and Hha I+:Hha I-, 0.17:0.83 for Msp I+:Msp I- in Dai tribe. The theoretical rates were 0.49 for Sma I and Hha I and 0.38 for Msp I in Yi tribe; and 0.45 for Sma I and Hha I, 0.28 for Msp I in Dai tribe, respectively. CONCLUSIONS: The allele frequencies and theoretical rates of these polymorphisms in vWF gene are different between Chinese populations and Caucasians. They should be useful for the carrier detection and prenatal diagnosis in vWD families of Chinese.

Alleles↗

PubMed1998

Experimental study on liver microcirculation disturbance following transplantation and the protective effect of prostaglandin E1 in the rat.

OBJECTIVE: To determine the effect of PGE1 on liver microcirculation disturbance following orthotopic liver transplantation in rats. METHODS: Forty male adult Wistar rats were divided randomly into 3 groups. Eight transplantations were established in both the experimental and control group, while in the sham group, the liver was dissected like in the experimental group, but no resection was performed. In the experimental group, PGE1(0.5 microgram/kg.min-1) was injected intravenously into the donor before the operation, and added (1 mg/L) to the flush and preservation fluid, while PGE1 was replaced by normal saline in the control group. Confocal laser scan microscopy, biochemical test, and optical and electronic microscopy were used. RESULTS: In the control group the reperfusion state was poor, leukocyte infiltration appeared in the center of lobule, and transaminase rose after transplantation. In the experimental group distinctive improvement was seen as compared with the control group (P < 0.05). Histological findings showed progressive degeneration and necrosis following transplantation in the control group, while in the experimental group the histological changes were improved to some degree by the use of PGE1. CONCLUSIONS: In liver transplantation, ischemic reperfusion damage may lead to hepatic microcirculation disturbance, which is the major cause of graft failure. Infusing PGE1 into the donor intravenously before ischemia and adding PGE1 to the cold storage fluid could improve hepatic microcirculation, and thus reducing ischemic reperfusion damage in liver transplantation.

Alprostadil↗

PubMed1998

[Clinical value of a rapid immunochromatographic assay in diagnosis and differential diagnosis of bone and joint tuberculosis].

OBJECTIVE: To evaluate the clinical value of a rapid immunochromatographic assay in diagnosis and differential diagnosis of bone and joint tuberculosis. METHOD: Antibodies in sera from 75 patients with active bone and joint tuberculosis, 69 patients with non-tuberculous bone and joint diseases and 72 healthy individuals were detected by the rapid immunochromatographic assay using ICT-TB kit. RESULT: The positive rate was found to be 80% in the patients with active bone and joint tuberculosis, while 90% in the group with spinal tuberculosis, 53% in the extra-spinal articular tuberculosis. The false positive rates were 4% and 3% respectively in those with other bone and joint diseases and healthy individuals. CONCLUSION: The assay is a rapid, sensitive and specific supplementary tool for the diagnosis of the bone and joint tuberculosis.

Antibodies, Bacterial↗

PubMed1998

[Azone-induced changes on corneal endothelium in rabbits].

OBJECTIVE: To investigate ocular toxic effect of azone at low concentrations in rabbits to determine whether this penetration enhancer has any value for ocular use. METHODS: 0.3%, 0.6%, 0.9% concentrations of azone in an ocular emulsion vehicle were studied. Rabbits in three experimental groups received topical 30 microl of 0.3%, 0.6%, 0.9% azone respectively three times daily for 4 weeks. Rabbits in control group 1 received 30 microl of vehicle without azone as negative control and rabbits in control group 2 received nothing as normal control. Clinical and histopathological examinations of rabbit cornea endothelial cells were made by slit-lamp biomicroscopy, light microscopy and scanning electron microscopy. RESULTS: No clinical and histopathological evidence of ocular toxicity occurred in all treated and control eyes. The concentration of azone used in this study was 3-9 times higher than that (at 0.1%) at which corneal penetration of hydrophilic compounds can be enhanced enormously. CONCLUSION: Azone has value for incorporation into ocular formulations to increase therapeutic action of many hydrophilic drugs.

Animals↗

PubMed1997

Dependence of the anti-chaperone activity of protein disulphide isomerase on its chaperone activity.

Protein disulphide isomerase (PDI) shows chaperone and anti-chaperone activities in assisting refolding of denatured and reduced lysozyme in redox Hepes buffer, but only chaperone activity in phosphate buffer and redox Hepes buffer containing 0.1 M NaCl. In non-redox Hepes buffer its anti-chaperone activity is very weak. PDI displays its anti-chaperone activity only for those substrates showing relatively low aggregation during refolding, and is strongly dependent on refolding conditions, of which ionic strength appears to be an important factor. The S-methylated PDI, fully active as a chaperone but devoid of isomerase activity, by itself shows only anti-chaperone activity, but reinforces rather than suppresses the chaperone activity of native PDI in the refolding of lysozyme. A fragment of PDI with the C-terminal peptide-binding sequence removed and devoid of chaperone activity does not show anti-chaperone activity in lysozyme refolding. It appears that the anti-chaperone activity of PDI is dependent on its chaperone activity.

Animals↗

PubMed1997

NMR solution structure of a two-disulfide derivative of charybdotoxin: structural evidence for conservation of scorpion toxin alpha/beta motif and its hydrophobic side chain packing.

The alpha/beta scorpion fold consisting of a short alpha-helix and beta-sheet is a structural motif common to scorpion toxins, insect defensins, and plant gamma-thionins that invariably contains three disulfides. CHABII is a two-disulfide derivative of the scorpion toxin charybdotoxin (ChTX), chemically synthesized by inserting two L-alpha-aminobutyric acids in place of the two half-cystine residues involved in the disulfide 13-33. This disulfide is one of the two disulfides which connect the alpha-helix to the beta-sheet. The solution structure of CHABII was determined at pH 6.3 and 5 degrees C using 2D NMR and simulated annealing from 513 distance and 46 dihedral angle constraints. The NMR structure of CHABII is well-defined as judged from the low value of the averaged backbone rms deviation between the 30 lowest energy structures and the energy-minimized mean structure ((rmsd) = 0.65 A for the entire sequence and 0.48 A for the segment 3-36). Analysis and comparison of the solution structures of CHABII and ChTX lead to the following conclusions: (i) the fold of CHABII is similar to that of ChTX as indicated by the low value of the averaged backbone atomic rms deviation between the 10 lowest energy solution structures of the two proteins (1.44 A); (ii) the packing of the hydrophobic core is well-preserved, underlying the critical structural role of the hydrophobic interactions even for such a small and cysteine-rich protein as ChTX.

Amino Acid Sequence↗

PubMed1997

Assembly and full functionality of recombinantly expressed dihydrolipoyl acetyltransferase component of the human pyruvate dehydrogenase complex.

The dihydrolipoyl acetyltransferase (E2) component of mammalian pyruvate dehydrogenase complex (PDC) consists of 60 COOH-terminal domains as an inner assemblage and sequentially via linker regions an exterior pyruvate dehydrogenase (E1) binding domain and two lipoyl domains. Mature human E2, expressed in a protease-deficient Escherichia coli strain at 27 degrees , was prepared in a highly purified form. Purified E2 had a high acetyltransferase activity, was well lipoylated based on its acetylation, and bound a large complement of bovine E1. Electron micrographs demonstrated that the inner core was assembled in the expected pentagonal dodecahedron shape with E1 binding around the inner core periphery. With saturating E1 and excess dihydrolipoyl dehydrogenase (E3) but no E3-binding protein (E3BP), the recombinant E2 supported the overall PDC reaction at 4% of the rate of bovine E2.E3BP subcomplex. The lipoates of assembled human E2 or its free bilipoyl domain region were reduced by E3 at rates proportional to the lipoyl domain concentration, but those of the E2.E3BP were rapidly used in a concentration-independent manner consistent with bound E3 rapidly using a set of lipoyl domains localized nearby. Given this restriction and the need for E3BP for high PDC activity, directed channeling of reducing equivalents to bound E3 must be very efficient in the complex. The recombinant E2 oligomer increased E1 kinase activity by up to 4-fold and, in a Ca2+-dependent process, increased phospho-E1 phosphatase activity more than 15-fold. Thus the E2 assemblage fully provides the molecular intervention whereby a single E2-bound kinase or phosphatase molecule rapidly phosphorylate or dephosphorylate, respectively, many E2-bound E1. Thus, we prepared properly assembled, fully functional human E2 that mediated enhanced regulatory enzyme activities but, lacking E3BP, supported low PDC activity.

Acetylation↗

PubMed1997

On the convergent evolution of animal toxins. Conservation of a diad of functional residues in potassium channel-blocking toxins with unrelated structures.

BgK is a K+ channel-blocking toxin from the sea anemone Bunodosoma granulifera. It is a 37-residue protein that adopts a novel fold, as determined by NMR and modeling. An alanine-scanning-based analysis revealed the functional importance of five residues, which include a critical lysine and an aromatic residue separated by 6.6 +/- 1.0 A. The same diad is found in the three known homologous toxins from sea anemones. More strikingly, a similar functional diad is present in all K+ channel-blocking toxins from scorpions, although these toxins adopt a distinct scaffold. Moreover, the functional diads of potassium channel-blocking toxins from sea anemone and scorpions superimpose in the three-dimensional structures. Therefore, toxins that have unrelated structures but similar functions possess conserved key functional residues, organized in an identical topology, suggesting a convergent functional evolution for these small proteins.

Amino Acid Sequence↗

PubMed1997

Acetaldehyde inhibits current through voltage-dependent calcium channels.

Ethanol consumption is often accompanied by an increase in both cardiac and vascular dysfunction. Underlying mechanisms may include direct actions of acetaldehyde (ACA), the principal by-product of ethanol metabolism, which has previously been shown to decrease both KCl- and nonrepinephrine-elicited contractions of isolated aortic rings. To determine whether ACA reduces vascular contractility through a direct action on sarcolemmal Ca2+ currents of vascular smooth muscle cells, Ca2+ channel currents in an aortic smooth muscle cell line (A7r5) were studied using the whole-cell patch clamping technique. With Ba2+ as the major charge carrier, Ca+ in the electrode, and TEA to block K+ currents, ramp depolarization activated an inward current consisting mostly of current through L-type Ca2+ channels. ACA caused a progressive decline in inward current, causing a significant reduction in 30 mM ACA of 21.2 +/- 4.3% (n = 6 cells; p < 0.01) within 4 min and 39.4 +/- 6.8% (n = 5 cells, p < 0.001) reduction within 8 min. Although the decline in inward current in 10 mM ACA was not significant at 4 min, significant (p < 0.05) reductions in 10 mM ACA were present at 8 min (15.5 +/- 3.5%, n = 9 cells) and 12 min (25.2 +/- 6.7%, n = 3 cells). There was no apparent shift in the voltage dependence of the current in response to ACA. The results of this study support the hypothesis that one of the underlying causes of ACA inhibition of potassium-elicited contraction is inhibition of voltage-dependent Ca2+ currents in smooth muscle cells.

Acetaldehyde↗

PubMed1997

Assignment of the human gene for KBF2/RBP-Jk to chromosome 9p12-13 and 9q13 by fluorescence in situ hybridization.

The transcription factor KBF2 has been characterized as a factor that binds to the NFkB site of mouse major histocompatibility complex (MHC) class I genes and its amino acid sequence has been shwn to be identical to those of members of the recombination signal-sequence binding protein (RBP-Jk) family. Previous studies by Amakawa et al. (Genomics 17, 306-315, 1993) demonstrated that the functional gene is localized at human chromosome 3q25. However, in the present study we showed by in situ hybridization with the functional KBF2/RBPJk cosmid clone that the gene is localized at 9p12-13 and 9q13, namely, at the same loci as pseudogenes that were reported previously (Zhang et al, Jpn J Human Genet 39, 391-401, 1994).

Animals↗

PubMed1997

Loss of oxyR in Mycobacterium tuberculosis.

The loss of the putative regulator oxyR and the associated dysfunction of oxidative stress response in Mycobacterium tuberculosis may have coincided with, or directly participated in, the evolution of this microorganism into the potent contemporary human pathogen. These phenomena may have implications for host-pathogen interactions in tuberculosis and for M. tuberculosis sensitivity to the front-line antituberculosis agent isoniazid.

Antitubercular Agents↗

PubMed1997

Magnetic resonance imaging in relation to functional outcome of pediatric closed head injury: a test of the Ommaya-Gennarelli model.

OBJECTIVE: To characterize late neuropathological findings of pediatric closed head injury (CHI), to assess depth of brain lesion in relation to acute severity, and to assess long-term outcome to test the Ommaya-Gennarelli model. METHODS: Magnetic resonance imaging (MRI) at least 3 months postinjury in a prospective sample (n 5 169) and at least 3 years after CHI in a retrospective sample (n 5 82) was studied. Lesion volume was measured by planimetry. Acute CHI severity was measured by the Glasgow Coma Scale. Patients were classified according to the depth of the deepest parenchymal lesion into no lesion, subcortical, and deep central gray/brain stem groups. The outcomes were assessed by the Glasgow Outcome Scale and the Vineland Adaptive Behavior Scale, which were performed at the time of the MRI in the retrospective sample and up to 3 years postinjury in the prospective sample. RESULTS: Focal brain lesions were present in 55.4% of the total sample. Depth of brain lesion was directly related to severity of acute impairment of consciousness and inversely related to outcome, as measured by both the Glasgow Outcome Scale and the Vineland Adaptive Behavior Scale. A rostrocaudal gradient of hemispheric lesion frequency was observed, whereas the posterior lesions of the corpus callosum were particularly common. Total lesion volume could not explain the depth of lesion effect. CONCLUSION: Our findings extend support for the Ommaya-Gennarelli model to pediatric CHI, indicating that depth of brain lesion is related to functional outcome. The relative frequency of focal brain lesions revealed by late MRI is higher than that of previous findings using acute computed tomography. Future investigations could explore whether depth of lesion observed using late MRI is sensitive to neuroprotective interventions.

Adolescent↗

PubMed1997

Enhancement in the effective thermal conductivity in rat spinotrapezius due to vasoregulation.

This study was undertaken to gain a better understanding of the countercurrent heat exchange of thermally significant blood vessels in skeletal muscle by measuring the vascular structure and flow in an exteriorized rat spinotrapezius muscle and estimating the enhancement in the effective thermal conductivity of the muscle. Detailed anatomic measurements of the number density and length of countercurrent vessel pairs between 45 and 165 microns diameter were obtained. Moreover, diameter and blood flow in the 1A to 3A vessels were measured for muscles in which pharmacological vasoactive agents were introduced, allowing one to vary the local blood flow Peclet number from 1 to 18 in the major feeding arteries. These combined measurements have been used to estimate the range of possible enhancement in the effective thermal conductivity of the tissue. The newly derived conduction shape factor in Zhu et al. for countercurrent vessels in two-dimensional tissue preparations was used in this analysis. Our experimental data indicated that the value of this conduction shape factor was about one-third to two-thirds the value for two countercurrent vessels of the same size and spacing in an infinite medium. The experiment also revealed that the Weinbaum-Jiji expression for keff was valid for the spinotrapezius muscle when the largest vessels were less than 195 microns diameter. A fivefold increase in keff was predicted for 195 microns diameter vessels. Vasoregulation was also shown to have a dramatic effect on keff. A tissue that exhibits only small increases in keff due to countercurrent convection in its vasoconstricted state can exhibit a more than fivefold increase in keff in its vasodilated state.

Animals↗

PubMed1997

L-Arogenate Is a Chemoattractant Which Can Be Utilized as the Sole Source of Carbon and Nitrogen by Pseudomonas aeruginosa.

L-Arogenate is a commonplace amino acid in nature in consideration of its role as a ubiquitous precursor of L-phenylalanine and/or L-tyrosine. However, the questions of whether it serves as a chemoattractant molecule and whether it can serve as a substrate for catabolism have never been studied. We found that Pseudomonas aeruginosa recognizes L-arogenate as a chemoattractant molecule which can be utilized as a source of both carbon and nitrogen. Mutants lacking expression of either cyclohexadienyl dehydratase or phenylalanine hydroxylase exhibited highly reduced growth rates when utilizing L-arogenate as a nitrogen source. Utilization of L-arogenate as a source of either carbon or nitrogen was dependent upon (sigma)(sup54), as revealed by the use of an rpoN null mutant. The evidence suggests that catabolism of L-arogenate proceeds via alternative pathways which converge at 4-hydroxyphenylpyruvate. In one pathway, prephenate formed in the periplasm by deamination of L-arogenate is converted to 4-hydroxyphenylpyruvate by cyclohexadienyl dehydrogenase. The second route depends upon the sequential action of periplasmic cyclohexadienyl dehydratase, phenylalanine hydroxylase, and aromatic aminotransferase.

Journal Article↗

PubMed1997

The Nef protein of human immunodeficiency virus type 1 enhances serine phosphorylation of the viral matrix.

The human immunodeficiency virus type 1 matrix (MA) protein is phosphorylated during virion maturation on its C-terminal tyrosine and on several serine residues. Whereas MA tyrosine phosphorylation facilitates viral nuclear import, the significance of MA serine phosphorylation remains unclear. Here, we report that MA serine but not tyrosine phosphorylation is strongly enhanced by Nef. Mutations that abrogated the membrane association of Nef and its ability to bind a cellular serine/threonine kinase greatly diminished the extent of virion MA serine phosphorylation. Correspondingly, a protein kinase coimmunoprecipitated with Nef could phosphorylate MA on serine in vitro, producing a phosphopeptide pattern reminiscent of that of virion MA. Recombinant p21-activated kinase hPAK65, a recently proposed relative of the Nef-associated kinase, achieved a comparable result. Taken together, these data suggest that MA is a target of the Nef-associated serine kinase.

Gene Products, gag↗

PubMed1997

Multicopy suppressors of phenotypes resulting from the absence of yeast VDAC encode a VDAC-like protein.

The permeability of the outer mitochondrial membrane to most metabolites is believed to be based in an outer membrane, channel-forming protein known as VDAC (voltage-dependent anion channel). Although multiple isoforms of VDAC have been identified in multicellular organisms, the yeast Saccharomyces cerevisiae has been thought to contain a single VDAC gene, designated POR1. However, cells missing the POR1 gene (delta por1) were able to grow on yeast media containing a nonfermentable carbon source (glycerol) but not on such media at elevated temperature (37 degrees C). If VDAC normally provides the pathway for metabolites to pass through the outer membrane, some other protein(s) must be able to partially substitute for that function. To identify proteins that could functionally substitute for POR1, we have screened a yeast genomic library for genes which, when overexpressed, can correct the growth defect of delta por1 yeast grown on glycerol at 37 degrees C. This screen identified a second yeast VDAC gene, POR2, encoding a protein (YVDAC2) with 49% amino acid sequence identity to the previously identified yeast VDAC protein (YVDAC1). YVDAC2 can functionally complement defects present in delta por1 strains only when it is overexpressed. Deletion of the POR2 gene alone had no detectable phenotype, while yeasts with deletions of both the POR1 and POR2 genes were viable and able to grow on glycerol at 30 degrees C, albeit more slowly than delta por1 single mutants. Like delta por1 single mutants, they could not grow on glycerol at 37 degrees C. Subcellular fractionation studies with antibodies which distinguish YVDAC1 and YVDAC2 indicate that YVDAC2 is normally present in the outer mitochondrial membrane. However, no YVDAC2 channels were detected electrophysiologically in reconstituted systems. Therefore, mitochondrial membranes made from wild-type cells, delta por1 cells, delta por1 delta por2 cells, and delta por1 cells overexpressing YVDAC2 were incorporated into liposomes and the permeability of resulting liposomes to nonelectrolytes of different sizes was determined. The results indicate that YVDAC2 does not confer any additional permeability to these liposomes, suggesting that it may not normally form a channel. In contrast, when the VDAC gene from Drosophila melanogaster was expressed in delta por1 yeast cells, VDAC-like channels could be detected in the mitochondria by both bilayer and liposome techniques, yet the cells failed to grow on glycerol at 37 degrees C. Thus, channel-forming activity does not seem to be either necessary or sufficient to restore growth on nonfermentable carbon sources, indicating that VDAC mediates cellular functions that do not depend on the ability to form channels.

Amino Acid Sequence↗