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Biomedical subjects

B Jiang

Publications and source records attributed to B Jiang.

At least 163 records · Page 9Linked to original sources
PubMed1995

The pathogenic role of the coccoid form of Helicobacter pylori.

Adherence of the coccoid forms of Helicobacter pylori to the gastric carcinoma cell line (KATO III) was examined by transmission electron microscopy. Specialized attachment sites such as the 'adhesion pedestal', 'cup-like indentation' and 'abutting adhesion' were seen in the interaction between coccoids and epithelial cells. These adherence patterns were similar to those observed with spiral forms in gastric biopsy specimens in vivo, suggesting a possible pathogenic role for the coccoids of H. pylori. With antigens prepared from both the coccoid and spiral forms, IgG antibodies reactive to H. pylori were detected using ELISA. Patients with gastroduodenal disease accounted for 74% (37/50) ELISA positives. Of the 50 healthy blood donors, 32 and 28% were seroreactive to coccoid and spiral antigens, respectively. These sera were further characterized by Western blot where immunoreactive protein bands of 128, 116, 110, 95, 91, 66, 60, 54, 50 and 33 kD were conserved in both the coccoid and spiral forms. These findings suggest that the coccoids could be a differentiated infective form of H. pylori, and that they could evoke an immune response from the host after invading the cells via specialized attachment sites.

Antigens, Bacterial↗
PubMed1994

Elastase enhances cAMP accumulation and the inhibition of DNA synthesis induced by OP-41483, a stable prostacyclin analogue, in vascular smooth muscle cells.

To define the physiological roles of elastase in the vascular wall, we examined whether elastase at low concentrations can modulate the proliferation of vascular smooth muscle cells (VSMC). Elastase itself at low concentrations from 1 to 50 ng/ml inhibited DNA synthesis dose-dependently in VSMC. However, phenylmethylsulfonyl fluoride-inactivated elastase failed to induce this inhibition. OP-41483, a stable analogue of prostacyclin, inhibited DNA synthesis and stimulated accumulation of cAMP in VSMC. Preincubation of VSMC for 24 h with 50 ng/ml elastase enhanced both inhibition of DNA synthesis and the accumulation of cAMP induced by OP-41483. Preincubation of VSMC with 12-O-tetradecanoylphorbol 13-acetate, an activator of protein kinase C (PKC), also enhanced cAMP accumulation induced by OP-41483. On the other hand, elastase failed to enhance OP-41483-induced cAMP accumulation in PKC down-regulated cells. Furthermore, coincubation with chelerythrine, an inhibitor of PKC, inhibited the enhancement of cAMP accumulation induced by preincubation with elastase. These results suggest that elastase at low concentrations can enhance the inhibition of VSMC proliferation induced by prostacyclin through the activation of protein kinase C.

Animals↗
PubMed1994

A new family of yeast genes implicated in ergosterol synthesis is related to the human oxysterol binding protein.

We have identified three yeast genes, KES1, HES1 and OSH1, whose products show homology to the human oxysterol binding protein (OSBP). Mutations in these genes resulted in pleiotropic sterol-related phenotypes. These include tryptophan-transport defects and nystatin resistance, shown by double and triple mutants. In addition, mutant combinations showed small but apparently cumulative reductions in membrane ergosterol levels. The three yeast genes are also functionally related as overexpression of HES1 or KES1 alleviated the tryptophan-transport defect in kes1 delta or osh1 delta mutants, respectively. Our study implicates this new yeast gene family in ergosterol synthesis and provides comparative evidence of a role for human OSBP in cholesterol synthesis.

Amino Acid Sequence↗
PubMed1994

Products of the porcine group C rotavirus NSP3 gene bind specifically to double-stranded RNA and inhibit activation of the interferon-induced protein kinase PKR.

The porcine group C rotavirus (Cowden strain) NSP3 protein (the group C equivalent of the group A gene 7 product, formerly called NS34) shares homology with known double-stranded RNA-binding proteins, such as the interferon-induced, double-stranded RNA-dependent protein kinase PKR. A clone of NSP3, expressed both in vitro and in COS-1 cells, led to the synthesis of minor amounts of a product with an M(r) of 45,000 (the expected full-length M(r) of NSP3) and major amounts of products with M(r)s of 38,000 and 8,000. Restriction enzyme digestion analysis prior to expression in vitro and amino-terminal sequence analysis suggest that the products with M(r)s of 38,000 and 8,000 are cleavage products of the protein with an M(r) of 45,000. The full-length protein and the product with an M(r) of 8,000, both of which contain the motif present in double-stranded RNA-binding proteins, bound specifically to double-stranded RNA. The products with M(r)s of 45,000 and 8,000 were also detected in Cowden strain-infected MA104 cells. NSP3 products expressed in COS-1 cells were capable of inhibiting activation of the double-stranded RNA-dependent protein kinase similar to other double-stranded RNA-binding proteins, and NSP3 products expressed in HeLa cells were capable of rescuing the replication of an interferon-sensitive deletion mutant of vaccinia virus.

Amino Acid Sequence↗
PubMed1994

Interactive effects of growth hormone and exercise on muscle mass in suspended rats.

Measures to attenuate muscle atrophy in rats in response to stimulated microgravity [hindlimb suspension (HS)] have been only partially successful. In the present study, hypophysectomized rats were in HS for 7 days, and the effects of recombinant human growth hormone (GH), exercise (Ex), or GH+Ex on the weights, protein concentrations, and fiber cross-sectional areas (CSAs) of hindlimb muscles were determined. The weights of four extensor muscles, i.e., the soleus (Sol), medial (MG) and lateral (LG) gastrocnemius, and plantaris (Plt), and one adductor, i.e., the adductor longus (AL), were decreased by 10-22% after HS. Fiber CSAs were decreased by 34% in the Sol and by 17% in the MG after HS. In contrast, two flexors, i.e., the tibialis anterior (TA) and extensor digitorum longus (EDL), did not atrophy. In HS rats, GH treatment alone maintained the weights of the fast extensors (MG, LG, Plt) and flexors (TA, EDL) at or above those of control rats. This effect was not observed in the slow extensor (Sol) or AL. Exercise had no significant effect on the weight of any muscle in HS rats. A combination of GH and Ex treatments yielded a significant increase in the weights of the fast extensors and in the CSA of both fast and slow fibers of the MG and significantly increased Sol weight and CSA of the slow fibers of the Sol. The AL was not responsive to either GH or Ex treatments. Protein concentrations of the Sol and MG were higher only in the Sol of Ex and GH + Ex rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Astrocytes modulate retinal vasculogenesis: effects on fibronectin expression.

Vasculogenesis is the formation of blood-vessels by differentiation of vascular precursor cells. Experiments using retinal models were designed to test the hypothesis that astrocytes influence this process by effects on the composition of the extracellular matrix. Retinal vasculogenesis was studied in relation to the migration of astrocytes and expression of the extracellular matrix proteins laminin and fibronectin by in vivo experiments in neonatal rats. The results show that astrocytes spread into the retina just ahead of the newly formed vessels, where they probably initiate vasculogenesis. They also establish that fibronectin, but not laminin, is expressed in the zone of vasculogenesis immediately prior to vessel formation. Increased amounts of fibronectin mRNA indicate that fibronectin is synthesized by cells within this same region during this same time period. Later, as the new vessels form, differentiation of endothelial cells is correlated with the appearance of pericytes in the vessel wall and laminin in the vascular basement membrane. In vitro experiments using conditioned medium approaches showed that astrocytes stimulate endothelial cell fibronectin expression. Taken together with the in vivo observations these in vitro results suggest that fibronectin expression is an essential component in the initiation of retinal vasculogenesis. This study is the first indication that astrocytes influence the fibronectin component of the extracellular matrix during retinal vasculogenesis and that expression of fibronectin precedes that of laminin in this process.

Animals↗
PubMed1994

Effects of an angiotensin II receptor antagonist, CV-11974, on angiotensin II-induced increases in cytosolic free calcium concentration, hyperplasia, and hypertrophy of cultured vascular smooth muscle cells.

The effects of CV-11974, a potent nonpeptide antagonist of the angiotensin II (AII) type-1 receptor (AT1), on cytosolic free calcium concentration ([Ca2+]i), hyperplasia, and hypertrophy of cultured vascular smooth muscle cells (VSMC) from rat aorta were studied. [Ca2+]i was measured by fura 2, and hyperplasia and hypertrophy were determined by incorporation of [3H]thymidine and [3H]leucine, respectively. CV-11974 had no effect on [Ca2+]i itself, but suppressed 10(-7) M AII-induced increase in [Ca2+]i dose dependently at concentrations from 10(-10) M and completely at 10(-7) M. CV-11974 suppressed both Ca2+ release from intracellular Ca2+ stores and Ca2+ influx from the extracellular space. However, CV-11974 had no effect on the increases in [Ca2+]i induced by prostaglandin F2 alpha (PGF2 alpha), a potent vasoconstrictor, or ionomycin, a Ca2+ ionophore. These results indicate that the suppressive effects of CV-11974 act on the binding of AII and its specific receptors. AII 10(-7) M increased the synthesis of DNA and protein to 1.5 and 1.7 times the control values, respectively. CV-11974 had no effect on synthesis of DNA or protein, but suppressed the AII-stimulated synthesis of DNA and protein dose dependently at concentrations > or = 10(-8) and 10(-10) M, respectively and completely at 10(-6) M. These results indicate that AII increases [Ca2+]i and synthesis of DNA and protein in VSMC through activation of AT1. CV-11974 showed no partial agonistic effects on AII. Thus, CV-11974 may act not only as an antihypertensive agent, but also as an inhibitor of vascular injury stimulated by AII.

Angiotensin II↗
PubMed1994

[Drug resistance of doxorubicin-resistant CHO cell line].

Some characteristics of doxorubicin-resistant CHO cell line (RC1) were studied by means of cell biological methods and SDS-PAGE electrophoresis. The resistance factor was 16.5-fold, and RC1 revealed cross-resistances to colchicine, actinomycin and harringtonine. By indirect immunofluorescence assay, P-glycoprotein was not detected. Compared with CHO, the doxorubicin (Dox) uptake and accumulation of RC1 decreased, but the membrane fluidity of RC1 increased. The reduction in drug accumulation was correlated with increase in membrane fluidity. Dox was mainly distributed in the cell nucleus of CHO, but in both cytoplasm and nucleus of RC1. This suggested that Dox was transported more slowly in RC1 cytoplasm than in CHO cytoplasm, resulting in less Dox entrance into the cell nucleus of RC1 than into that of CHO. We also found that a 30-40 kDa nuclear protein which was expressed normally in CHO disappeared in RC1.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

[Studies on three-dimensional configuration of diaphragmatic lymphatics and absorptive mechanism of lymph from the peritoneal cavity].

Three-dimensional configuration of diaphragmatic lymphatics in five fetuses was studied by the lymphatic casts of scanning electron microscope and transmission electron microscope. A new resin, PAES-3, prepared by piperylene, acrylic ester and styrene was used instead of Mercox. The diaphragmatic lymphatics formed rich networks. There were two layers of lymphatic networks, i.e. the submesothelial network and the deeper network, in the muscular portion and only one layer in the tendinous portion of the diaphragm. The lymphatic networks were denser in the tendinous portion than those in the muscular portion. The lymphatic network were mainly composed of collecting lymphatic vessels, anastomosing side branches and lymphatic capillaries. The side branches often communicated the submesothelial network with the deeper network in the muscular portion. The collecting lymphatics were connected at regular intervals by way of transverse side branches in the tendinous portion. Numerous constrictions and notches showed the presence of lymphatic valves and were often found on the cast surface of the collecting lymphatic vessels and the side branches. The lymphatics extended as far as the terminal branches and can be recognized as broad, flattened and blind-ended. In present study, three-dimensional configuration of human diaphagmatic lymphatics was first described. It was suggested that the passageway of the lymph flow of the peritoneal cavity may be explained. From the peritoneal stomata, the lymph of the peritoneal cavity flowed into the channels under the peritioneum, then into the lymphatic lacunae and finally into the lymphatic networks under the diaphragmatic pleura.

Absorption↗
PubMed1994

Motion sickness in mice and conditioned taste aversion.

Forty-eight male mice in 6 groups were studied. Conditioned taste aversion (CTA) in mice was produced by various motions including cross-coupled acceleration, rotation to two directions (with or without visual field) and linear acceleration. Deprived of water for 24 hours, the mice were exposed to motion immediately after drinking a novel solution, 0.15% saccharin. All groups received two pairings of CTA training related to motion. The results showed that both of cross-coupled and rotation produced frank CTA and former was far more obvious than the latter. In addition, motion with visual field had a trend to intensify sickness response.

Animals↗
PubMed1994

[The diagnosis and surgical treatment of cholelithiasis of the caudal lobe of the liver].

From June 1983 to Feb. 1993, a total of 528 patients with hepatobiliary stones were surgically treated by hepatoenterostomy with a basin-typed plasty at the stump of hilar bile duct. Among them there were 220 cases suffering from cholelithiasis in the caudal lobe, with an average age of 39.1 years. Preoperative sonography, PTC, ERCP, and CT all failed to find stones in this particular location. In the 220 cases, simple caudal lobe stones accounted for 14.5%, caudal lobe stones with bile duct abnormality accounted for 46.8%, and stones with stricture of the duct for 46.4%. Surgical treatment included bile duct dilatation, cholangiotomy, and cholangioplasty and direct chilangiotomy in the caudal lobe.

Adolescent↗
PubMed1994

A force plate and display system for studying ground reaction forces in dogs.

We have developed and implemented a low cost system for measuring ground reaction forces in dogs with normal and abnormal ambulation as they walk or trot over a floor mounted plate that measures vertical and horizontal forces. Orthogonally mounted strain gages measure the forces imposed. A bridge amplifier conditions the signals which are sampled and converted to digital form for display on an operator initiated graphical user interface (GUI) which displays the forces as a function of time on the screen of a Macintosh computer. The system also allows the input of timing of the velocity of approach to the plate and the foot strike can be monitored (via tap reply) on the computer screen to verify the fidelity of the foot strike on the active surface of the plate. The data gathered on a particular strike is stored as a "raw" signal, analyzed and recorded in a spread sheet text format for later analysis.

Analog-Digital Conversion↗
PubMed1994

FS2. a mamba venom toxin, is a specific blocker of the L-type calcium channels.

The peptide FS2 is a mamba venom toxin, consisting of 60 amino acids, three residues of which are different from those of calciseptine (CaS), a natural L-type Ca2+ channel blocker. The biological activities of synthetic FS2 for L-type Ca2+ channels were determined under comparisons to those of CaS and nitrendipine, a 1,4-dihydropyridine derivative. Similar to CaS, FS2 competitively inhibited the binding of [3H]nitrendipine to rat brain synaptosomal membranes on Lineweaver-Bulk plot, with Kd value of 210 nM, which was similar to that of CaS being 290 nM, but did not affect binding of an N-type Ca2+ channel ligand omega-[125I]-conotoxin GVIA to the membranes. Pretreatment of A7r5 cells with either FS2 or CaS at concentrations of 10(-8) M and greater for 5 min significantly and dose-dependently reduced 10(-6) M Bay K8644-induced increase in the cytosolic free Ca2+ concentration ([Ca2+]i) of the cells determined by the fluorescent Ca2+ indicator fura-2, with the half inhibitory concentrations (IC50) of 2.3 x 10(-8) and 2.7 x 10(-8) M, being similar to that of the IC50 value of nitrendipine (4.4 x 10(-8) M). These observations indicate that FS2, similar to CaS, is an active natural L-type Ca2+ blocker sharing the binding site on the channels with the 1,4-dihydropyridines.

Amino Acid Sequence↗
PubMed1993

RNA sequence of astrovirus: distinctive genomic organization and a putative retrovirus-like ribosomal frameshifting signal that directs the viral replicase synthesis.

The genomic RNA of human astrovirus was sequenced and found to contain 6797 nt organized into three open reading frames (1a, 1b, and 2). A potential ribosomal frameshift site identified in the overlap region of open reading frames 1a and 1b consists of a "shifty" heptanucleotide and an RNA stem-loop structure that closely resemble those at the gag-pro junction of some retroviruses. This translation frame-shift may result in the suppression of in-frame amber termination at the end of open reading frame 1a and the synthesis of a nonstructural, fusion polyprotein that contains the putative protease and RNA-dependent RNA polymerase. Comparative sequence analysis indicated that the protease and polymerase of astrovirus are only distantly related to the respective enzymes of other positive-strand RNA viruses. The astrovirus polyprotein lacks the RNA helicase domain typical of other positive-strand RNA viruses of similar genome size. The genomic organization and expression strategy of astrovirus, with the protease and the polymerase brought together by predicted frameshift, most closely resembled those of plant leuteoviruses. Specific features of the sequence and genomic organization support the classification of astroviruses as an additional family of positive-strand RNA viruses, designated Astroviridae.

Base Sequence↗
PubMed1993

Calciseptine binding to a 1,4-dihydropyridine recognition site of the L-type calcium channel of rat synaptosomal membranes.

Calciseptine (CaS) is a natural peptidic L-type Ca2+ channel blocker consisting of 60 amino acids with four disulfide bonds. The effects of synthetic CaS on the binding of various ligands to Ca2+ channels of rat brain synaptosomal membranes were studied. The membranes possessed specific binding sites for L-type Ca2+ channel ligands [3H]nitrendipine, [3H]diltiazem and [3H]verapamil, derivatives of 1,4-dihydropyridine, benzothiazepine and papaverine, respectively, and also for N-type Ca2+ channel ligand omega-[125I]-conotoxin GVIA (omega-[125I]CTX). Lineweaver-Bulk plot analysis disclosed that CaS competitively inhibited the binding of [3H]nitrendipine, with maximal binding capacity of 0.19 pmol/mg protein and dissociation constant (Kd) of 290 nM, being about 10(3) times the Kd value of [3H]nitrendipine. Similar to nitrendipine, CaS noncompetitively enhanced the binding of [3H]diltiazem, but did not affect the binding of [3']verapamil. CaS at up to 10.0 microM did not affect the binding of omega-[125I]CTX. These observations indicate that CaS shares the properties of 1,4-dihydropyridine derivatives, and allosterically modulates the binding of other L-type Ca2+ channel ligands.

Animals↗