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Biomedical subjects

S Jiang

Publications and source records attributed to S Jiang.

At least 325 records · Page 18Linked to original sources
PubMed1994

Three-dimensional structure-activity analysis of a series of porphyrin derivatives with anti-HIV-1 activity targeted to the V3 loop of the gp120 envelope glycoprotein of the human immunodeficiency virus type 1.

Using comparative molecular field analysis (CoMFA), a 3D-QSAR model was developed for 21 porphyrin derivatives which have anti-HIV-1 activity and bind to the V3 loop of the envelope glycoprotein gp120 of the human immunodeficiency virus type 1. A significant PLS cross-validated r2cv (0.590) was obtained, indicating that the model could be used as a predictive tool for further design of porphyrin analogs. The model revealed at least three important sites for favorable electrostatic interactions and indicated favorable and unfavorable steric interaction sites. It was found that the occurrence of at least three positively charged and several hydrophobic amino acid residues is highly conserved at fixed positions of gp120 V3 loop sequences. This may support the validity of the proposed model and the hypothesis that porphyrins containing anionic and hydrophobic groups may interact with some of the highly conserved positively charged and hydrophobic sites, respectively, of the V3 loop. These interactions may induce conformational changes in the gp120 envelope glycoprotein leading to inhibition of virus entry into cells and of syncytium formation (cell-to-cell fusion) and thus to inhibition of virus replication.

Amino Acid Sequence↗
PubMed1994

Separate metabolic pathways leading to DNA fragmentation and apoptotic chromatin condensation.

Apoptosis is the predominant form of cell death observed in a variety of physiological and pathological conditions such as cancer involution, insect metamorphosis, the development of the immune and nervous systems, and embryogenesis. The typical nuclear changes taking place in apoptotic cells include extensive condensation of chromatin and internucleosomal DNA fragmentation into units of 200 base pairs. However, the mechanisms responsible for both chromatin condensation and DNA fragmentation have yet to be elucidated. In this study, micrococcal nuclease and the divalent cations, Ca2+ and Mg2+, were applied to isolated nuclei in an attempt to reconstitute in vitro the digestion of genomic DNA associated with apoptosis. Micrococcal nuclease was found to induce a typical pattern of DNA fragmentation, but did not give rise to chromatin condensation, whereas Ca2+/Mg2+ induced both chromatin condensation and DNA fragmentation in isolated mouse liver nuclei. When the endonuclease inhibitor ZnCl2 was used, the DNA fragmentation induced by Ca2+/Mg2+ in nuclei could be completely inhibited, but chromatin condensation still occurred. For comparison, intact liver cells were treated with valinomycin, a potassium ionophore, which gave rise to an atypical cell death, with chromatin condensation appearing without DNA fragmentation. Our results suggest that endonuclease activation in apoptosis is neither necessary nor sufficient to induce chromatin condensation, and that DNA fragmentation and chromatin condensation may be triggered through separate pathways during apoptosis.

Animals↗
PubMed1994

Identification and characterization of a novel tyrosine kinase from megakaryocytes.

Protein-tyrosine kinases play pivotal roles in cell signal transduction. We have isolated a cDNA clone encoding a novel human intracytoplasmic tyrosine kinase, termed matk (megakaryocyte-associated tyrosine kinase). Expression of matk mRNA was predominantly found in cells of megakaryocytic lineage. The matk cDNA clone encodes a polypeptide of 527 amino acids and has closest sequence similarity to the csk tyrosine kinase. Sequence comparisons also indicate that matk contains src homology region 2 and 3 domains but lacks the NH2-terminal myristylation signal, the negative regulatory tyrosine (Tyr-527), and the autophosphorylation site (Tyr-416) corresponding to those found in src. Antibodies raised against the NH2 terminus of matk immunoprecipitated a 60-kDa protein from the CMK human megakaryocyte cell line. Expression of matk mRNA was up-regulated in megakaryocytic cells induced to differentiate by the phorbol ester. Based on its restriction in expression and its modulation during in vitro differentiation, it is likely that matk participates in signal transduction during megakaryocytopoiesis.

Base Sequence↗
PubMed1994

Plasma membrane K+/H(+)-ATPase from Leishmania donovani.

Leishmania donovani has an active K+/H+ exchange system on the surface membrane. Modulation of external K+ concentration resulted in a corresponding change in internal pH (pHi) suggesting a link between proton and potassium transport. Although a Na+/H+ antiporter is present on the plasma membrane, its sensitivity to amiloride suggests that it operates independent of K+/H+ exchange. Reduction of cellular ATP with NaN3 and KCN inhibits K+/H+ exchange showing thereby that the process is energy dependent. The K+/H+ exchange is sensitive to inhibitors of the gastric K+/H(+)-ATPase. It is concluded that the H(+)-ATPase previously reported on the plasma membrane of L. donovani is in fact a K+/H(+)-ATPase.

Adenosine Triphosphate↗
PubMed1994

Intracellular Ca2+ signals activate apoptosis in thymocytes: studies using the Ca(2+)-ATPase inhibitor thapsigargin.

The endoplasmic reticular Ca(2+)-ATPase inhibitor, thapsigargin, was used to study the role of an increase in cytosolic free calcium concentration ([Ca2+]i) as a signal for the activation of thymocyte apoptosis. Treatment of rat thymocytes with thapsigargin resulted in an early sustained increase in [Ca2+]i followed by extensive DNA fragmentation. Agarose gel electrophoresis revealed that the pattern of DNA fragments was typical of endonuclease-mediated internucleosomal cleavage. In addition, confocal microscopy studies showed the formation of apoptotic nuclei in thapsigargin-treated thymocytes. The concentrations of thapsigargin required to induce DNA fragmentation and [Ca2+]i increase in thymocytes were identical and so were the kinetics of thapsigargin-induced DNA fragmentation and formation of apoptotic nuclei. The lowest concentration of thapsigargin needed to activate apoptosis was 1 nM. Thapsigargin-induced [Ca2+]i increase and thymocyte apoptosis were inhibited in cells incubated in nominally Ca(2+)-free medium or pretreated with the intracellular Ca2+ chelator, bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/acetoxymethyl ester. Removal of extracellular free Ca2+ with 5 mM EGTA at different time points after thapsigargin addition revealed a time dependency of about 2 h for the sustained increase in [Ca2+]i to trigger apoptosis in thymocytes. Thus, we conclude that the signal provided by the thapsigargin-induced [Ca2+]i increase is sufficient to activate thymocyte apoptosis.

Animals↗
PubMed1994

Analysis of polarity of bovine and rabbit embryos by scanning electron microscopy.

Cellular polarization during preimplantation development of the embryo is believed to be a crucial event in the transition of a zygote to a blastocyst stage embryo with morphologically and functionally differentiated cell types. While extensive studies have been done on polarity development in mouse embryos, little information is available in other species, particularly in cattle. The objective of this study was to examine the initiation of polarity by microvilli distribution on blastomeres of cattle and rabbit embryos using scanning electron microscopy (SEM). Bovine embryos were obtained by in vitro fertilization of in vitro-matured follicular oocytes. Rabbit embryos of various stages were collected from superovulated rabbits. Intact embryos and isolated blastomeres were examined in both species. Blastomeres from 1- to 8-cell embryos in both cattle and rabbits showed no polarity. The onset of transitional polarization of microvillous distribution occurred in some blastomeres of cattle embryos at the 9- to 15-cell stage; but typical, distinct polarity was not manifested until after the 16-cell stage with approximately 40% polar cells per embryo. In the rabbit blastomere polarity occurred one cell cycle later, with 46% polar cells per embryo after the 32-cell stage. The difference in cell numbers at the time polarity is evident is probably related to the different cell stages for embryo compaction and blastocyst formation in the two species.

Animals↗
PubMed1994

Development of a new laser-Doppler microvelocimetering and its application in patients with coronary artery stenosis.

A new Laser-Doppler microvelocimetering (LDMV) was developed to study blood flow in individual vessels in patients with coronary artery stenosis. The LDMV measures steady blood flow velocity, diameter of vessels and pulsation flow. In addition, the effects of China's traditional herbs--Salvia Mitiorrhyza and other drugs--on the blood flow in the patients were investigated. LDMV constitutes a new quantitative procedure and is a promising tool for rapid monitoring of tissue perfusion in cardiovascular disease and estimating the action of drugs on microcirculation.

Blood Flow Velocity↗
PubMed1994

[Immunohistochemical study of the olfactory mucosa and vomeronasal organ in rat, guinea pig and human fetus].

Immunohistochemical examination for neuron-specific enolase (NSE), S-100 protein and cytokeratin (CK) was performed in the olfactory mucosa and Jacobson's vomeronasal organ of rat, guinea pig and human fetus. The results indicated that: 1) The combined immunohistostaining used in this study made it possible to examine the normal morphology and pathology of the olfactory mucosa; 2) The NSE immunoreactivity was recognized in the Jacobson's vomeronasal organ of the adult rats and guinea pigs. The vomeronasal organ of human fetuses below 5 months showed positive immunoreactivity for NSE, but the NSE immunoreactivity of the vomeronasal organ in fetuses above 7 months was not confirmed. So we conclude that human vomeronasal organ is possibly a regressive organ. It is unlikely to have any olfactory function as it does in rodent animals.

Animals↗
PubMed1994

[Study of topographic mapping of the auditory middle latency response in the guinea pigs].

Topographic mapping techniques were applied to study the auditory middle latency response (MLR) in 10 awake guinea pigs. Fourteen holes (1mm in diameter) were drilled through the skull regions and epidural electrodes were fixed on the skull with the dental cement, then auditory MLR were recorded with 13 electrodes, and MLR brain maps were obtained with a concerto system. Our result supports the hypothesis of multiple MLR generators. The main components are wave A, wave B and wave C. The foci localise the temporal lobe contralateral to the stimulated ear. The other components are wave M- and wave M+. The foci localise parietal and occipital lobes. Each wave responds differently to procaine. The result suggests that wave A, wave M- and wave M+ are generated from the subcortex, while wave B, wave C generated from the cortex.

Acoustic Stimulation↗
PubMed1994

[The embryonic development of the ostiomeatal complex from 8 to 40 weeks].

The embryonic development of the ostiomeatal complex from 8-40 weeks was studied under the light microscope. From our observation, the uncinate process was visible on the laterosuperior portion of the inferior turbinate at 8 week's gestation. By 12 weeks, the ethmoid bulla was first identifiable on the lateral wall of the middle meatus. The primordial ethmoidal infundibulum and primordial maxillary sinus were seen developing lateral to the uncinate process in the middle meatus. The air cells of the middle turbinate may be normal development of the ethmoidal labyrinth. Congenital nasal septum deviation may cause malformation of the ostiomeatal complex.

Embryonic and Fetal Development↗
PubMed1994

[Amplification in vitro and identification of small subunit ribosomal DNA fragment of Plasmodium falciparum].

According to computer analysis of SSUrDNA sequences of Plasmodium, other protozooa and human, two oligonucleotide primers were designed. A DNA fragment, about 570 base pairs, was successfully amplified by two temperature point polymerase chain reaction from the genomic DNA of cultivated erythrocytic stage of P. falciparum FCC/YN (Simao), but no fragment was obtained from that of P. vivax, L. donovani, T. gondii and humans. It has been confirmed that the amplified fragment was indeed expected SSUrDNA segment of P. falciparum by means of restriction endonuclease digestions and Northern blot hybridization.

Animals↗
PubMed1994

Comparison of standard locked-ward treatment versus open-ward rehabilitation treatment for chronic schizophrenic patients. A one-year controlled trial in Canton.

A priority for psychiatric rehabilitation workers in China is to develop less-restrictive methods for managing the estimated 2500 chronically institutionalised patients who are symptomatically stable and have adequate psychosocial functioning but have no family members who are able or willing to take them home. We transferred 45 chronic schizophrenic male in-patients to an open-door rehabilitation ward where they were given as much freedom as possible and encouraged to take part in occupational, social, and recreational activities. The Nurses Observation Scale for Inpatient Evaluation (NOSIE) was used to compare the psychosocial functioning of the 43 patients who completed the year-long trial with that of 43 similar patients who received standard in-patient treatment on a locked ward. Over the year, the experimental group showed a significant improvement in overall functioning, whereas the control group showed no improvement. These findings suggest that open-door rehabilitation wards situated within the hospital can mobilise latent psychosocial functioning and may be a good method for re-introducing chronic schizophrenic patients in China back into the community.

Activities of Daily Living↗
PubMed1994

[Lymphokine-activated killer cell induced from cord blood].

In this article, the studies on the method of inducing lymphokine-activated killer (LAK) cells from cord blood lymphocytes, the killing ability of LAK cells to tumor subculture cells K562 and Raji, the comparison of the killing activity to tumor subculture cells among LAK cells from cord blood lymphocytes, adult's Peripheral blood lymphocytes (PBL) and gynecologic cancer patient's PBL was presented. The changes of the OKT antigens on the surface of cord blood LAK cells tested with monoclonal antibodies was described. The morphologic changes resulted from the killing activity of LAK cells to target cells were observed by microscopy and electron-microscopy after a definite time co-incubation of the LAK cells and Raji cells. The results showed that: (1) LAK cells could be induced from cord blood and the induced LAK cells could remarkably kill the tumor subculture cell lines including nature killer (NK)-sensitive K562 cells as well as NK-insensitive Raji cells; (2) The activity of cord blood LAK cells is higher than that of the LAK cells from gynecologic cancer patient's PBL, But no significant difference with that of the LAK cells from normal adult's PBL; (3) T+3, T+8, the OKT antigens of cord blood LAK cells are just the same as human LAK cells from other sources; (4) After a definite time co-incubation, the cord blood LAK cells and Raji cells could form atypical rosette-circles under light microscopy. In the field of transmission electron-microscopy, the cord blood LAK cells had a certain active mobility. Raji cells, when incubated with the cord LAK cells for 4 hours, would become apoptosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Additive effect of erythropoietin and heme on murine hematopoietic recovery after azidothymidine treatment.

The ability of combination treatment with erythropoietin (Epo) and heme to rescue hematopoietic activity in mice from the suppressive effect of azidothymidine (AZT) was determined. Exposure of mice to AZT for 5 weeks produced marked anemia, thrombocytopenia, neutropenia, and weight loss, whereas mice that received Epo and heme for 3 subsequent weeks showed significant alleviation of AZT cytotoxicity. Treatment with Epo (10 U for 5 times/week) stimulated hematopoietic recovery in the AZT-treated animals and reduced the severe anemia and thrombocytopenia by 3 weeks. Administration of a lower Epo dose (1 U Epo) resulted in only a modest retardation of AZT-induced anemia, although, when combined with heme, there was a great improvement in recovery of erythropoiesis. The combination of heme with Epo (10 U) produced the optimum response, resulting in almost normal recovery of bone marrow cellularity as well as recovery of burst-forming units-erythroid (BFU-E) and splenic hematopoietic progenitor content (colony-forming unit-spleen [CFU-S]) by the end of 3 weeks of post-AZT treatment. Treatment with heme alone markedly enhanced the recovery of BFU-E and CFU-S, as well as body weight post-AZT; however, this recovery was not to the extent seen in combination with Epo (10 U). Long-term bone marrow cultures (LTBMCs) established from mice exposed to AZT for 8 weeks showed a marked reduction in cellularity and this was completely alleviated when mice received heme and Epo (10 U) for 3 weeks after 5 weeks of AZT administration. The additive effect of heme and Epo was seen in BFU-E production, as well as in CFU-S production, in LTBMCs. Thus, heme exerts a significant protective effect on hematopoietic progenitors in vivo and may be of potential clinical use in combination with Epo to promote effective erythropoiesis in the setting of AZT therapy.

Anemia↗