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Biomedical subjects

S Jiang

Publications and source records attributed to S Jiang.

At least 289 records · Page 16Linked to original sources
PubMed1996

[The cochlea in short-term culture].

In order to establish organotypic culture of the cochlea, the dissection of the early postnatal mouse cochlea and its morphology in short-term culture were investigated. The viability of hair cells in the culture was assessed using differential interference contrast (DIC) microscopy and double-staining with fluorescein diacetate (FDA) and propidium iodide (PI). The hair cells remained viable and did not show any signs of damage for up to 8-18 hours. When incubated in Hank's solution containing 1 mmol/L dihydrostreptomycin, the hair cells initially deteriorated in 0.5-4.5 hours and progressed to entire degeneration after 10-20 hours. In addition to its utilization in organotypic culture, the cochlea in short-term culture can be used as a valuable model for studying cellular and molecular neurobiology of the inner ears.

Animals↗
PubMed1996

[The results of tympanoplasty with titanium prostheses].

In order to improve the hearing results of tympanoplasty, we performed the operation on 113 cases (124 ears) by using ossicular replacement prostheses made of Titanium. The results demonstrated that among all the operated ears, 73/124 (58.9%) had obtained a narrow gap (< 20 dB HL) between BC and AC, 89/124 (71.8%) had regained socially acceptable hearing ability. The total effective rate of hearing gain (> 10 dB HL) was 115/124 (92.7%). No reject reaction and recurrent cholesteatoma were found. This operation method, based on animal experiments and applied anatomic study of human suprastapedial structure, resulted in a high effective rate and maked hearing improvement with a relatively large magnitude. It was because of the application of a new material-Titanium, which has high biocompatibility with human body tissues. The ossicular replacement prosthesis was appropriately designed and delicately manufactured. It fitted well and could be tightly joined to the suprastapedial structure, and uneasy to be displaced. In addition, we adopted the method of enlarging tympanic isthmus, that lead to well aeration in mastoid and attic, thus set the tympanic membrane to the best state of mobility. All these contributed to the effective hearing gain.

Adolescent↗
PubMed1996

[Nasal septal deviation in fetuses].

To investigate the etiology of nasal septal deviation, twenty-four fetal sinonasal specimens aged between 8-40 weeks of gestation were studied under light microscopy. Sixteen fetal heads aged between 32-40 weeks were examined using 2.7 mm 5 degrees Wolf endoscope. Five of 24 fetal sinonasal specimens were confirmed histopathologically to have deviated nasal septum. 1 of 16 fetal heads was considered to have nasal septal deviation. The existence of nasal septal deviation in fetuses was confirmed. To explain the embryogenesis, we suggested that maldevelopment of vomeropalatal complex is responsible for the formation of nasal septal deviation in fetuses.

Female↗
PubMed1996

[Impulsive angular acceleration evoked middle and long latency potentials in guinea pigs].

Middle and long latency evoked potentials have been successfully recorded in guinea pigs with impulsive angular acceleration delivered by a specially developed motor. The middle latency responses elicited by impulsive angular acceleration had peaks at about 9 ms, 15 ms and 24 ms with a mean peak to peak amplitude of about 28muV and the long latency responses after the delivering of impulsive angular acceleration in guinea pigs composed of a triphasic wave with a mean peak to peak amplitude of about 50 muV occurring during 32 ms to 130 ms with respect to the start of head stimuli. A series of experiments lead to the conclusion that the middle latency responses to impulsive angular acceleration are middle latency vestibular evoked potentials. The long latency response elicited by impulsive angular acceleration is not a specific response of auditory or vestibular pathway.

Animals↗
PubMed1996

[Histopathology of the temporal bone in adhesive otitis media].

To understand the histopathological changes of adhesive otitis media (AOM) in human, temporal bone sections processed with the celloidin-embedding technique were reviewed. In the 338 pairs of temporal bone specimens, 20 cases (26 ears) showed characteristics of AOM. The results showed that the lesions of AOM were extensive, involving all middle ear structures including tympanic muscles, round and oval windows. There were various pathological changes, in every stage of inflammation and tissue repair. According to the main pathological characteristics, histopathological changes of the 26 ears were staged as exudation, inflammatory grannlation formation, histocyte response and collegen proliferation. As the process progressed, the amount of inflammatory cells and exudate decreased with the increase of fibroblasts. Certain factors were speculated to play an important role in the process of fibrosis. The authors analysed the difficulties in the management of AOM and causes of the unsatisfactory therapeutic results. Possible measures to improve treatment results were proposed.

Adult↗
PubMed1995

Identification and characterization of a novel related adhesion focal tyrosine kinase (RAFTK) from megakaryocytes and brain.

We have isolated a cDNA encoding a novel human intracytoplasmic tyrosine kinase, termed RAFTK (for a related adhesion focal tyrosine kinase). In addition, we have cloned and characterized the murine homolog of the human RAFTK cDNA. Comparison of the deduced amino acid sequences of human RAFTK and murine Raftk cDNAs revealed 95% homology, indicating that RAFTK is highly conserved between these species. The RAFTK cDNA clone, encoding a polypeptide of 1009 amino acids, has closest homology (48% identity, 65% similarity) to the focal adhesion kinase (pp125FAK). Comparison of the deduced amino acid sequences also indicates that RAFTK, like pp125FAK, lacks a transmembrane region, myristylation sites, and SH2 and SH3 domains. In addition, like pp125FAK, RAFTK contains a kinase domain flanked by large N-terminal (426 residues) and C-terminal (331 residues) domains, and the C-terminal region contains a predicted proline-rich stretch of residues. In fetal tissues, RAFTK expression was abundant in brain, and low levels were observed in lung and liver. In adult tissues, it was less restricted, indicating that RAFTK expression is developmentally up-regulated. Expression of RAFTK was also observed in human CD34+ marrow cells, primary bone marrow megakaryocytes, platelets, and various areas of brain. The human RAFTK gene was assigned to human chromosome 8 using genomic DNAs from human/rodent somatic cell hybrid lines. The mouse Raftk gene was mapped to chromosome 14, closely linked to gonadotropin-releasing hormone. Using specific antibodies for RAFTK, a approximately 123-kDa protein from the human megakaryocytic CMK cell line was immunoprecipitated. Treatment of the megakaryocytic CMK cells with thrombin caused a rapid induction of tyrosine phosphorylation of RAFTK protein. The structural features of RAFTK suggest that it is a member of the focal adhesion kinase gene family and may participate in signal transduction in human megakaryocytes and brain as well as in other cell types.

Amino Acid Sequence↗
PubMed1995

Molecular cloning and functional expression of a human pancreatic secretin receptor.

Through binding to high affinity receptors, secretin is the major hormonal stimulant of ductular bicarbonate secretion in the pancreas, contributes toward enzyme secretion from pancreatic acinar cells, and has been implicated as a pancreatic growth factor. In this work, we utilized hybridization screening of a human pancreatic cDNA library to clone a 1.8-kb cDNA encoding a 440 amino acid protein 81% identical to the rat pancreatic secretin receptor. COS-7 cells transfected with this cDNA bound secretin with a high affinity, and vasoactive intestinal peptide with a lower affinity, appropriate for a secretin receptor. Receptor-bearing COS-7 cells also exhibited an increase in cyclic AMP generation in response to secretin stimulation. Studies analyzing the role of this receptor in human pancreatic physiology and pathophysiology are currently underway in our laboratory.

Amino Acid Sequence↗
PubMed1995

Structural and functional studies of the intracellular tyrosine kinase MATK gene and its translated product.

We recently cloned the cDNA which encodes a novel megakaryocyte-associated tyrosine kinase termed MATK. In this study, we have cloned and characterized the human MATK gene as well as the murine homolog of human MATK cDNA and performed functional studies of its translated product. Comparison of the deduced amino acid sequences of human and murine MATK cDNAs revealed 85% homology, indicating that MATK is highly conserved in mouse and human. The human gene consists of 13 exons interrupted by 12 introns. The genetic units which encode the SH3 and SH2 domains are located on separate exons. The putative ATP binding site (GXGXXG) is localized on exon 7, and the entire catalytic domain is subdivided into seven exons (7-13). Somatic cell hybrid analysis indicated that human MATK gene is located on chromosome 19 while the murine Matk gene is located on chromosome 10. The immediate 5'-flanking region was highly rich in GC sequences, and potential cis-acting elements were identified including several SP1, GATA-1, APRE, and APRE1. Antisense oligonucleotides directed against MATK mRNA sequences significantly inhibited megakaryocyte progenitor proliferation. Functional studies indicated that MATK can phosphorylate the carboxyl-terminal conserved tyrosine of the Src protein. These results support the notion that MATK acts as a regulator of p60c-src in megakaryocytic cells and participates in the pathways regulating growth of cells of this lineage.

Adenosine Triphosphate↗
PubMed1995

Cumulus cell function during bovine oocyte maturation, fertilization, and embryo development in vitro.

Several contemporary micromanipulation techniques, such as sperm microinjection, nuclear transfer, and gene transfer by pronuclear injection, require removal of cumulus cells from oocytes or zygotes at various stages. In humans, the cumulus cells are often removed after 15-18 hr of sperm-oocyte coincubation to assist the identification of the fertilization status. This study was designed to evaluate the function of cumulus cells during oocyte maturation, fertilization, and in vitro development in cattle. Cumulus cells were removed before and after maturation and after fertilization for 0, 7, 20, and 48 hr. The cumulus-free oocytes or embryos were cultured either alone or on cumulus cell monolayers prepared on the day of maturation culture. Percentages of oocyte maturation, fertilization, and development to cleavage, morula, and blastocyst stages and to expanding or hatched blastocysts were recorded for statistical analysis by categorical data modeling (CATMOD) procedures. Cumulus cells removed before maturation significantly reduced the rate of oocyte maturation (4-26% vs. 93-96%), fertilization (0-9% vs. 91-92%), and in vitro development at all stages evaluated. Cumulus cells removed immediately prior to in vitro fertilization (IVF) or 7 hr after IVF reduced the rates of fertilization (58-60% and 71%, respectively, vs. 91-92% for controls), cleavage development (40-47% and 53-54% vs. 74-78% for controls), and morula plus blastocyst development (15% and 24% vs. 45%, P < 0.05). Cumulus cell co-culture started at various stages had no effect on fertilization and cleavage development but significantly improved rates of embryo development to morula or blastocyst stages (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effects of N-acetyl-L-cysteine on T-cell apoptosis are not mediated by increased cellular glutathione.

Thiol-containing antioxidants such as N-acetyl-L-cysteine (NAC) are known to inhibit apoptosis, although it is unclear whether this effect is direct or mediated through modulation of intracellular glutathione (GSH). In the present study, NAC treatment of the murine T-cell hybridoma DO-11.10 was found to inhibit apoptosis triggered by anti-CD3 antibody but enhance the process when induced by 6-alpha- methylprednisolone. HPLC measurements showed that these effects were not correlated with the levels of GSH or glutathione disulfide (GSSG) in the cells. Similar effects on DNA fragmentation were obtained when the experiments were repeated in the presence either of a specific inhibitor of GSH biosynthesis (buthionine sulfoximine) or the isomer N-acetyl-D-cysteine which cannot be enzymatically converted into GSH. We conclude that NAC can have divergent effects on apoptosis independent of changes in either the amount or redox state of intracellular GSH.

Acetylcysteine↗
PubMed1995

Beneficial effect of oocyte activation prior to and during nuclear transfer in cattle using in vitro matured oocytes 24 h of age.

This research was designed to study in vitro development of bovine nuclear transferred embryos using enucleated young in vitro matured oocytes 24 h of age as recipient cytoplasts activated prior to nuclear transfer. The oocytes were enucleated and then activated with electric pulse at 24 h of age followed by incubation with cycloheximide for 6-7 h before nuclear transfer and membrane fusion with a blastomere of the 16-32 cell stage. This new protocol effectively improved cleavage (68 vs 17%, p < 0.05) and morula/blastocyst development of reconstructed embryos (29 vs 6%, p < 0.05), compared to similar nuclear transfer procedure without prior activation of recipient oocytes. Corresponding rates of cleavage and morula/blastocyst development for oocytes activated similarly without nuclear transfer were 49 and 19%. Factors affecting nuclear transfer were also compared. Two electric pulses for fusion increased rates of fusion (76 vs 60%, p < 0.05) and subsequent development of cloned embryos (32 vs 11%, p < 0.05). Cytochalasin B treatment following nuclear transfer manipulation seemed not to be beneficial in improving development of cloned embryos (p > 0.05). Both co-culture systems with buffalo rat liver (BRL) cells and cumulus cells promoted development of cloned embryos compared to the controls (28, 21 vs 0%, p < 0.05). The BRL cell system seemed to be better for manipulated embryos by reducing embryolysis.

Animals↗
PubMed1995

Multifaceted consequences of anti-gp41 monoclonal antibody 2F5 binding to HIV type 1 virions.

A human monoclonal antibody (MAb) (2F5) neutralizing a variety of laboratory strains and clinical isolates of the human immunodeficiency virus type 1 (HIV-1) and binding to an epitope of the envelope glycoprotein gp41 encompassing the amino acid sequence ELDKWA has been described (Muster T et al., J Virol 1993;67:6642-6647). It was suggested that an immunogen eliciting virus-neutralizing antibodies having a specificity similar to that of MAb 2F5 should be considered as a component of HIV-1 vaccines. Efforts in this direction would benefit from understanding the mechanism whereby MAb 2F5 neutralizes the infectivity of HIV-1. The segment of gp41 encompassing residues ELDKWA has so far not been directly implicated in initiation of infection by HIV-1, suggesting that MAb 2F5 might affect other sites on HIV-1 envelope glycoproteins playing a role in virus entry into target cells. We provide here evidence that MAb 2F5 binding to HIV-1 virus particles decreases the accessibility or conformation of the gp41 fusion domain and of gp120 domains, including the binding site for the CD4 cell receptor. These apparently indirect consequences of MAb 2F5 binding to HIV-1 are likely to account for or contribute to the virus-neutralizing activity of this MAb.

Amino Acid Sequence↗
PubMed1995

Modulation of corneal heme oxygenase expression by oxidative stress agents.

Heme oxygenase, the rate-limiting enzyme in the degradation of heme to bile-pigments and carbon monoxide, is induced in response to increased oxidative stress and is believed to provide a cytoprotective effect. We investigated the role of heme oxygenase in cultured rabbit corneal epithelial cells (RCE), and its potential to alleviate oxidative stress-induced cell damage. Heme oxygenase in RCE was effectively and potently induced by most metals tested, including tin, silver, and gold, and cytokines such as IL-6, and TGF beta. Stannous chloride and heme-induced heme oxygenase mRNA by 40 and 100 fold within 1-3 hours and increased enzyme activity by 9.2- and 10-fold, respectively, over a 24 hour period. IL-6, TGF beta and H2O2 induced heme oxygenase by 2-3 fold. Zinc protoporphyrins were effective inhibitors of heme oxygenase activity in vitro. However, when incubated with cells for 24 h they induced heme oxygenase mRNA but decreased or had no effect on its activity. Administration of heme, SnCl2, and H2O2 resulted in some degree of glutathione perturbation (GSH/GSSG). However, in all cases, depletion of glutathione was exacerbated if heme oxygenase was simultaneously inhibited. Conversely, perturbation of glutathione levels was minimized if heme oxygenase was induced by heme or stannous chloride. These results demonstrate that RCE cells exhibit functional heme oxygenase activity which is inducible in response to inflammatory cytokines and oxidative stress agents and suggest a cytoprotective role for heme oxygenase against cell injury.

Animals↗
PubMed1995

Occurrence of fecal indicator bacteria in surface waters and the subsurface aquifer in Key Largo, Florida.

Sewage waste disposal facilities in the Florida Keys include septic tanks and individual package plants in place of municipal collection facilities in most locations. In Key Largo, both facilities discharge into the extremely porous Key Largo limestone. To determine whether there was potential contamination of the subsurface aquifer and nearby coastal surface waters by such waste disposal practices, we examined the presence of microbial indicators commonly found in sewage (fecal coliforms, Clostridium perfringens, and enterococci) and aquatic microbial parameters (viral direct counts, bacterial direct counts, chlorophyll a, and marine vibriophage) in injection well effluent, monitoring wells that followed a transect from onshore to offshore, and surface waters above these wells in two separate locations in Key Largo in August 1993 and March 1994. Effluent and waters from onshore shallow monitoring wells (1.8- to 3.7-m depth) contained two or all three of the fecal indicators in all three samples taken, whereas deeper wells (10.7- to 12.2-m depth) at these same sites contained few or none. The presence of fecal indicators was found in two of five nearshore wells (i.e., those that were < or = 1.8 miles [< or = 2.9 km] from shore), whereas offshore wells (> or = 2.1 to 5.7 miles [< or = 3.4 to 9.2 km] from shore) showed little sign of contamination. Indicators were also found in surface waters in a canal in Key Largo and in offshore surface waters in March but not in August. Collectively, these results suggest that fecal contamination of the shallow onshore aquifer, parts of the nearshore aquifer, and certain surface waters has occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Clostridium perfringens↗
PubMed1995

[Calcium channels in bullfrog saccular hair cells].

In order to understand the cochlear physiology at a cellular and molecular level, Ca2+ channels were studied in cell-attached recordings from the basolateral membrane of the bullforg saccular hair cells with the EPC-9 patch-clamp system. Pipettes contained 110 mM Ba2+ and the membrane potential was zeroed with isotonic potassium aspartate. Data acquisition and analysis were performed using E9SCREEN and M2LAB software. L-type channel was distinguished by a single-channel conductance of 26 pS, activation range between -10 and +40 mV and intense activity even at a holding potential of -40 mV. The L-type channel showed characteristic bursts of brief openings (mode 1) interrupted occasionally by longer openings (mode 2). Bay K 8644 promoted the mode 2 activity and nifedipine inhibited L-type channel activity. Another type of calcium channels, 20 pS channel, was detected by -50 to +10 mV depolarizing steps from a holding potential of -40 mV or -80 mV. This channel was insensitive to dihydropyridines and resembled the N-type channel.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1995

Changes in the endocochlear potential and cochlear blood flow induced by ATP infusion and arterial occlusion.

To assess the relationship between cochlear blood flow (CBF) and auditory function, a procedure of intravital microscopy for observations of the lateral wall vessels of the cochlea coupled with the simultaneous measurement of the endocochlear potential (EP) was established in guinea pigs with gradual ischemia of the cochlea. It was found that occlusions of both common carotid arteries and one of the vertebral arteries produced a minor reduction in CBF with no significant alteration in the EP. When intravenous infusion of ATP induced sharp and severe decreases in CBF, the EP varied only slightly from the baseline in some animals while there were no alteration in others. Furthermore, ATP infusions combined with arterial occlusions caused even more severe declines in CBF and a moderate decrease in the EP. The results indicate that not only does the CBF satisfy the basic needs of the processes of cochlear function, but also has a regulatory mechanism to ensure the normal function of the cochlea in the ischemia condition. It was also found that the changes in the stria vascularis vessels induced by decreases in blood pressure (BP) and heart rates were more severe than those of the spiral ligament vessels. This phenomenon indicated that the stria vascularis vessels were more sensitive to decreases of BP and heart rates.

Adenosine Triphosphate↗
PubMed1995

[Analysis of antigenity of membranous labyrinth proteins of guinea pigs].

An electrophoretic dot immunobinding assay and a modified western blotting method were established. The components and antigenity of the membranous labyrinth proteins of guinea pigs were analysed. There are the same epitopes between some components of the antigen, between the antigen and extractives of acoustic nerve, cochlear nuclei, kidney and Klebsiella pneumoniae. The antigen distributes in stria vascularis, spiral ligament, spiral ganglion, the organ of Corti and Reissner's membrane etc.

Animals↗