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Biomedical subjects

S Jiang

Publications and source records attributed to S Jiang.

At least 307 records · Page 17Linked to original sources
PubMed1995

Lack of Ca2+ involvement in thymocyte apoptosis induced by chelation of intracellular Zn2+.

BACKGROUND: Chelation of intracellular Zn2+ with N, N, N', N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) triggers apoptosis predominantly in mature thymocytes. A rise in intracellular-free Ca2+ concentration ([Ca2+]i) has been associated with induction of thymocyte apoptosis by a variety of agents. Zn2+ can affect intracellular Ca2+ homeostasis, so the aim of this study was to investigate whether TPEN-induced apoptosis is mediated by Ca2+ signalling. EXPERIMENTAL DESIGN: The possible role of Ca2+ in TPEN-induced apoptosis was investigated. Apoptotic markers used were DNA cleavage into oligonucleosomal fragments and formation of apoptotic nuclei. The change in [Ca2+]i in thymocytes after TPEN treatment was monitored using the fluorescence Ca2+ indicator dye, fura-2. The requirement of an increase in [Ca2+]i for TPEN-induced apoptosis was examined in thymocytes preloaded with the intracellular Ca2+ buffer, bis-(o-aminophenoxy)-ethane-N, N,N',N'-tetraacetic acid, or incubated in nominally Ca(2+)-free medium supplemented with EGTA. The effect of an increase in [Ca2+]i on TPEN-induced DNA fragmentation was studied by using thapsigargin or ionomycin to elevate [Ca2+]i in thymocytes. RESULTS: No increase in [Ca2+]i could be detected before DNA fragmentation in thymocytes during TPEN treatment. Buffering intracellular Ca2+ with bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid or incubating cells in nominally Ca(2+)-free medium with EGTA had little effect on TPEN-induced DNA fragmentation and formation of apoptotic nuclei. Increasing thymocyte [Ca2+]i with thapsigargin or ionomycin administration during TPEN treatment resulted in an additive effect on TPEN-induced DNA fragmentation in thymocytes. CONCLUSIONS: Our study shows that TPEN induces apoptosis in thymocytes by Ca(2+)-independent mechanisms and that apoptosis triggered by Zn2+ chelation and [Ca2+]i elevation affects distinct thymocyte subpopulations.

Animals↗
PubMed1995

Interaction between intercalation type anticancer drugs and DNA studied by ultraviolet resonance Raman spectroscopy.

The interaction of typical intercalation type anticancer drugs, adriamycin (ADM) and aclacinomycin (ACM), with calf thymus DNA was studied first with ultraviolet resonance Raman spectroscopy (UVRRS). The results demonstrate that the important information such as intercalation sites of drugs, the electronic interaction and the hydrogen bonds between drugs and DNA can be obtained by UVRRS. The method can also show the influence of drugs on DNA conformation and hydrogen bonds between bases of DNA.

Aclarubicin↗
PubMed1995

[Confocal images of cochlear outer hair cells in the guinea pigs].

The effects of ACh, ATP and high K+ on intracellular calcium concentration Ca2+ in outer hair cells (OHC) of the guinea pig cochleae were observed with the use of Ca2+ sensitive dye Fluo-3 and laser scanning confocal microscope. Ca2+ increase induced by these chemicals had individual temporal and spatial features. Moreover, high K+ solutions induced contraction and bending of OHC too. Taking advantage of the "optical sectioning" facility of confocal microscopy, morphography of Fluorescein-labelled living OHC and PI-dyed nuclei was reconstructed three-dimensionally. The application of confocal microscopy in OHC physiological and morphological research was discussed.

Animals↗
PubMed1995

[Studies on diagnosis of falciparum malaria based on amplifying specific SSUrDNA fragment with nested PCR].

Two pairs of primers specific to small subunit ribosomal DNA of Plasmodium falciparum were designed and the expected SSUrDNA fragment was amplified for detecting P. falciparum infection with double-temperature-nested polymerase chain reaction using DNA prepared by boiling method. The results showed that the nested PCR could amplify a constant size of desired SSUrDNA fragment of P. falciparum which was further confirmed by digestion of restriction endonuclease and could detect parasitemia level of 0.8 x 10(-6). It has great potentials for identifying Plasmodium species in ring form of erythrocytic stage and detecting mixed Plasmodium infections. Therefore, it is suggested that this method is sensitive, accurate, simple and rapid in detecting Plasmodium falciparum in blood samples for malaria diagnosis.

Animals↗
PubMed1995

[Acridine mutagen ICR-170 induced developmental suppression of ovary and vitelline gland in female Schistosoma japonicum].

Mice of Kunming strain were infected with Schistosoma japonicum cercariae previously incubated with various concentrations of acridine mutagen ICR-170 for different time durations. At 6 weeks after infection, the mice were autopsied. The results showed that 24 out of 28(85.7%) adult female worms had deformed or lacked ovaries and vitelline glands when the cercariae were treated with the agent at a concentration of 10 micrograms/ml and incubated at 30.5 degrees C for 30min. No apparent changes were observed in the male worms inhabiting the mesenteric and portal veins with the females worms in their gynecophoral canals. The mutagenized female schistosomes obtained from the present experiment might be served as another form of attenuated worms for the induction of protective immunity.

Aminoacridines↗
PubMed1995

Controlling cancerous pain with analgesic powder for cancers.

Analgesic powder for cancers, composed of more than 20 Chinese drugs, was applied externally to 91 patients with various kinds of cancers for management of cancerous pain. The results showed that it was remarkably effective in 42 cases, fairly effective in 22, effective in 22, and ineffective in 5, the total effective rate being 94.51%. Animal experiments indicated that the pain threshold was evidently higher in mice treated with this powder on the site of femoral artery of the hind limbs than that of the controls without application of this powder.

Administration, Cutaneous↗
PubMed1995

[Effect of focal cochlear vascular lesion on endocochlear potential in guinea pigs].

The alterations in endocochlear potential(EP) in response to the total cochlear ischemia induced by varied experimental manipulations have been studied. However, whether damage to the focal microvessel in the lateral wall of the cochlea can affect the EP value is still unknown. In current investigations, we adapted a photochemical method to produce focal microvessel injury in the lateral wall of the guinea pig cochlea and examine effects of these insults on EP in the same region. It was found that the small focal microvessel lesion (approximately 0.2mm x 0.3mm) did not induce significant changes in EP value. Furthermore, the relative large microvessel lesion (approximately 0.2mm x 0.3mm) did not induce significant changes in EP value. Furthermore, the relative large microvessel lesion (approximately 0.2mm x 0.8mm) produced only a slight decrease in the EP value with experimental procedures and these changes were not significantly different as compared with those in the control group subjects. The results from this study suggest that after focal microvessels in the lateral wall of the cochlea are injured, some compensation mechanisms may play a role in maintaining the cochlear function.

Animals↗
PubMed1995

[Laboratory diagnosis of autoimmune sensorineural hearing loss with modified western blotting method].

Anti-membranous labyrinth proteins antibody were tested in suspectable autoimmune sensorineural hearing loss (ASNHL) with a modified western blotting method. 5 strongly positive bands (including 68,000) existed in at most 18 of 25 cases (72%). This method was found to be more sensitive than the routine one (40%). Anti-membranous proteins of Klebsiella pneumoniae antibodies were also found in 7 of 9 tested patients.

Adolescent↗
PubMed1995

[Histopathologic observation and 3DCT reconstruction of the nasal cavity and paranasal sinuses in children with cleft palates].

The morphologic characteristics of nasal cavity and paranasal sinuses in children with cleft palate were studied by means of histopathology, CT scan, computer-aided image analysis and three-dimensional CT (3DCT) reconstruction. Our results suggested (1) incompetent velopharynx is the main reason for high incidence of sinusitis in children with cleft palate; (2) computer-aided image analysis, together with 3DCT reconstruction, may calculate and demonstrate the volume and shape of the paranasal sinuses. We believe this method may be useful in the future to study the development of the paranasal sinuses in children. 3DCT reconstruction provides a better understanding of the size and invasion of the lesion located in nasal cavity and paranasal sinuses. This method may be used as an aid to teaching and surgical planning.

Child↗
PubMed1995

[Platelet factor 4 acts as both inhibitor and protector of hematopoietic precursor cells: possible mechanism of action].

We have previously shown that platelet factor 4 (PF 4) is a potent inhibitor of megakaryocytopoiesis and that it may protect stem cells from 5-fluorouracil (5-FU) cytotoxicity. In the present work, the effects of human PF 4 on megakaryocyte (MK) growth from human CD34+ cord blood (CB) cells were studied in comparison with transforming growth factor beta 1 (TGF-beta 1). Development of MK from CD34+ cells in both plasma clot culture and liquid culture was significantly inhibited by PF 4 (5 micrograms/ml) and TGF beta 1 (1 ng/ml). Inhibition of cell growth by PF 4 was reversible judging from the fact that the CD34+ cells preincubated with PF 4 could regenerate colonies after washing and replating into the cultures. By contrast, TGF-beta 1 pretreated CD34+ cells gave rise to few colonies following replating. Moreover, incubation of CD34+ cells with PF 4 in liquid culture caused an increase in the number of both stem cell factor (SCF)-binding cells and CD34 antigen-bearing cells, and exhibited greater capacity to form MK colonies than control after the treatment of 5-FU. In vivo in mice, twice injections of PF 4 at 40 micrograms/kg with an interval of 6 h followed by one injection of 5-FU at 150 mg/kg resulted in a significant increase in the number of colony-forming cells with high proliferative potential (HPP-CFC) and colony-forming unit-megakaryocyte (CFU-MK) in bone marrow. In exponentially growing human erythroleukemia cells (HEL), the addition of PF 4 prolonged cell cycle progression and therefore resulted in an increased cell population in S phase, as determined by flow cytometric analysis. Different from PF 4, TGF-beta 1 blocked more cells in G 1 phase. These results demonstrate that PF 4 and TFG-beta 1 inhibit MK development from CD34+ CB cells by different mechanisms and suggest that PF 4, unlike TGF-beta 1, exerts its inhibitory effect on cell growth in a reversible and S phasespecific manner by which it protects stem cells and MK progenitor cells from 5-FU cytotoxicity.

Animals↗
PubMed1995

[The morphologic changes of outer hair cells induced by hypotonic, hypertonic medium and electromotility].

For further understanding of biological features of cochlear outer hair cells, outer hair cells were isolated from guinea pig cochlea with micromechanical method and observed when the microosmotic concentration of their culture medium were changed. Outer hair cells shortened 3.14 +/- 0.76% (P < 0.01) within one minute after the osmotic concentration of the medium decreased to 280 mmol/L, accompanied with increase of cell diameter. Elongation of 3.34 +/- 1.09% (P < 0.05) of outer hair cells were observed after osmotic concentration of the medium was increased to 320 Os mmol/L, accompanied with decrease of cell diameter. Oscillatory elongation and shortening of outer hair cells and oscillatory displacements of intracellular organelles could be observed when square wave electrical potentials were applied across isolated outer hair cells. Hypertonic high potassium medium (K+ 100 mmol/L, 320 Osmmol/L) decreased the oscillatory movement of the cells by about 43.14% (negative potential) and 46.17% (positive potential) (P < 0.05). The shape of outer hair cells restored when the medium was isotonic. The mechanism and biological bases of outer hair cell movement were discussed.

Animals↗
PubMed1995

[Scanning electron microscopic observation of human vestibular sensory epithelia].

Three-dimensional structures of human vestibular sensory epithelia were studied under scanning electron microscope. The saccular macula showed an "L" pattern and increased in thickness near the striola. The utricular macula appeared like an open shell. Flask and test-tube shaped hair cells were identified as type-I and type-II sensory cells respectively. Stereocilia were arranged in a step like progression; the kinocilium was near the longest stereocilium and looked more flexible than stereocilia. The tallest stereocilia and kinocilia faced away from the striola toward the periphery in the macula sacculi, and toward each other along the striola in the utricular maculae. Polarization directed to the utricle in the lateral crista, and away from the utricle in the anterior and posterior cristae. Otoconia varied in size and shaped like crystals with pyramidal ends.

Adolescent↗
PubMed1995

[Early diagnosis of acoustic neuroma].

The diagnostic findings in 31 patients (32 ears) with acoustic neuromas are reported. In patients suspicious of acoustic neuroma, case history and clinical examination are important. In our material of 31 patients with acoustic neuromas, hearing loss was presented in 94% (slow onset 87%, sudden onset 10% and fluctuating 3%), tinnitus in 91%, vestibular symptoms (dizziness or vertigo) in 62%. It should be stressed that in patients with unilateral hearing loss (or tinnitus) or vestibular symptoms, it is necessary to exclude the presence of an acoustic neuroma. In addition, the trigeminal never was affected in 34%, which was encountered in tumours larger than 26-40 mm. There was a positive correlation between duration of symptoms and size of the tumour, but there was no correlation between hearing loss and size of the tumour. Brainstem response audiometry (ABR) exhibited a very high sensitivity (100%), making it a suitable single test for screening patients suspected to have an acoustic neuroma.

Adolescent↗
PubMed1994

Cytokine production by primary bone marrow megakaryocytes.

Primary human bone marrow megakaryocytes were studied for their ability to express and release cytokines potentially relevant to their proliferation and/or differentiation. The purity of the bone marrow megakaryocytes was assessed by morphologic and immunocytochemical criteria. Unstimulated marrow megakaryocytes constitutively expressed genes for interleukin-1 beta (IL-1 beta), IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNF-alpha), by the polymerase chain reaction (PCR) and Northern blot analysis. At the protein level, megakaryocytes secreted significant amounts of IL-1 beta (53.6 +/- 3.6 pg/mL), IL-6 (57.6 +/- 15.6 pg/mL), and GM-CSF (24 +/- 4 pg/mL) but not TNF-alpha. Exposure of human marrow megakaryocytes to IL-1 beta increased the levels of IL-6 (87.3 +/- 2.3 pg/mL) detected in the culture supernatants. Transforming growth factor-beta was also able to stimulate IL-6, IL-1 beta, and GM-CSF secretion, but was less potent than stimulation with phorbol-12-myristate-13-acetate (PMA). The secreted cytokines acted additively to maintain and increase the number of colony-forming unit-megakaryocytes colonies (approximately 35%). These studies demonstrate the production of multiple cytokines by isolated human bone marrow megakaryocytes constitutively or stimulated in vitro. The capacity of human megakaryocytes to synthesize several cytokines known to modulate hematopoietic cells supports the concept that there may be an autocrine mechanism operative in the regulation of megakaryocytopoiesis.

Bone Marrow↗
PubMed1994

The beta-aspartyl phosphate intermediate in a Leishmania donovani promastigote plasma membrane P-type ATPase.

The phosphorylated intermediate of a plasma membrane P-type ATPase in Leishmania donovani has been further characterized. The formation of the phosphorylated intermediate is sensitive to several ATPase inhibitors including vanadate, dicyclohexyl carbodiimide (DCCD), N-ethylmaleimide (NEM), and fluorescein isothiocyanate (FITC). These inhibitors affect purified immunoprecipitated protein as well as total plasma membrane fractions. Oligomycin, an inhibitor of mitochondrial ATPases, and ouabain, an inhibitor of Na+/K(+)-ATPases, had no effect on the formation of the phosphorylated intermediate. The ATPase phosphoprotein was acid stable and dephosphorylated at alkaline pH, indicating the presence of the acyl phosphate chemical linkage. Analysis of the phosphorylated amino acid by reduction with sodium boro[3H]hydride identified the residue as aspartate, confirming the formation of a beta-aspartyl phosphate intermediate. These data indicate the presence of a 105 kDa P-type ATPase on L. donovani plasma membrane that is mechanistically similar to to other P-type enzymes of higher eukaryotes.

Adenosine Triphosphatases↗
PubMed1994

Human kit ligand (stem cell factor) modulates platelet activation in vitro.

The human stem cell factor (SCF), also termed c-Kit ligand (KL), is a hematopoietic growth factor produced by mesenchymal cells that induces proliferation of bone marrow progenitor cells, megakaryocytes, and mast cells via interaction with c-Kit, its cognate receptor. Expression of the c-kit gene was identified in human platelets by the polymerase chain reaction technique. The presence of the c-Kit receptor was demonstrated by the specific binding of 125I-KL/SCF to ADP-stimulated platelets. The identity of the c-Kit protein was confirmed by immunoreactivity with an anti-c-Kit-specific antibody and by its characterization as a phosphotyrosine-containing protein. Under constitutive conditions, c-Kit was found to be tyrosine-phosphorylated and was associated with a 85-kDa phosphoprotein that could be a fragment of phosphatidylinositol 3-kinase. These data indicate the presence of a new platelet surface molecule that could function in platelet activation. We demonstrate that the secondary wave of platelet aggregation and serotonin secretion induced by epinephrine and ADP, but not by the thromboxane analog U46619, was augmented by KL/SCF. The effect of KL/SCF on epinephrine/ADP-induced platelet activation appeared to be mediated in part through the thromboxane pathway. These data suggest that KL/SCF could modulate hemostasis via interaction with platelets, particularly in conditions where mesenchymal cells are exposed to circulating blood elements, such as in wound healing or atherosclerosis.

Adenosine Diphosphate↗
PubMed1994

Involvement of Ca2+ in the formation of high molecular weight DNA fragments in thymocyte apoptosis.

Internucleosomal DNA fragmentation (DNA laddering) and formation of apoptotic bodies have long been considered characteristic features of apoptosis. However, recent work has shown that formation of high molecular weight DNA fragments precedes internucleosomal cleavage and may involve mechanisms that differ from those responsible for DNA laddering. Here, we show that glucocorticoid treatment of human thymocytes stimulated the formation of high molecular weight DNA fragments by Ca(2+)- and endonuclease-mediated mechanisms. Either the removal of Ca2+ from the medium or pretreatment of the cells with the intracellular Ca2+ chelator, BAPTA-AM, prevented the formation of large DNA fragments. Further, treatment of the thymocytes with the microsomal Ca(2+)-ATPase inhibitor, thapsigargin, which caused a sustained increase in intracellular Ca2+ concentration, was in itself sufficient to activate high molecular weight DNA fragmentation. Our results show that Ca(2+)-dependent mechanisms promote the multistep chromatin cleavage in human thymocyte apoptosis.

Apoptosis↗