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Biomedical subjects

G Shi

Publications and source records attributed to G Shi.

At least 91 records · Page 5Linked to original sources
PubMed1997

[Spinal segment distribution of neural innervation related houhai acupoint--studied by CB-HRP tracing method focused on observation of the dendrites of spinal motor neurons].

The spinal segment distribution of neural innervation related Houhai acupoint in rats has been investigted by using horseradish peroxidase conjugated cholera toxin B subunit (CB-HRP) tracing technique. Spinal motoneurons (Mn) in L6-S1 were labeled retrogradely by CB-HRP, and their features have been characterized: 1) their marginal plexus of the dendrites radially projected to the lateral and/or anterior funiculus and their distal portions forming subpial dendritic plexus; 2) the medial dendrites ran along the ventral margin of the gray commissure and their distal portions surrounded the central canal' forming a subependymal dendritic plexus. Both of them are Golgi-phobic. Some distal branches of dendrites penetrated to the contralateral gray matter. The dendritic arbors of the labeled motoneurons in the group of electro-acupuncture or group of acupoint-inoculation with sheep red blood cells contracted in comparison with that in the normal control group. The primary sensory transganglionic labeled fibers and preterminal fibers revealed by CB-HRP in the dorsal horn and dorsal commissural nucleus of the spinal cord (L5-S2) converged and overlaped with the dendrites of retrogradely labeled motoneurons. The results indicated there is a reflect circuit of afferent-integration-efferent neuro-network in the spinal cord related Houhai acupoint. The Mns retrogradely labeled by CB-HRP in the L6-S1 segments might be involved in Houhai acupuncture.

Acupuncture Points↗
PubMed1997

[In vitro study on arsenic trioxide-inducing apoptosis in primary acute promyelocytic leukemie cells].

OBJECTIVE: To illustrate mechanisms of arsenic trioxide(As2O3) in the treatment of acute promyelocytic leukemia (APL). METHODS: Cell-DNA content distribution, CD11b and CD33 antigens and nitroblue tetrazolium (NBT) reduction were evaluated in fresh APL cells from six APL patients treated in vitro with As2O3. RESULTS: As2O3 had double effects on the cells inducing apoptosis and inducing partial differentiation at higher and at lower drug concentrations, respectively. As2O3 (0.1 approximately 2.0 micromol/L) could rapidly modulate and degrade APL-specific marker molecule PML-RARalpha protein, which could play an important role in the effects of As2O3 on APL cells. CONCLUSION: As2O3 had double effects (induction of apoptosis and partial differentiation) on APL cells through the modulation and degradation of PML-RARalpha proteins.

Apoptosis↗
PubMed1997

[Double effects of arsenic trioxide (As2O3) on acute promyelocytic leukemic cell line].

OBJECTIVE: To investigate the effects of a wide range of concentrations of As2O3 on NB4 cells. METHODS: Cell morphology, cell-DNA content distribution, CD11b and CD33 antigens and nitroblue tetrazolium (NBT) reductions were evaluated in an APL cell line NB4 cells with or without As2O3 treatment. In addition, immunofluorescent analysis for APL marker molecule PML-RAR alpha was also performed. RESULTS: 1-2 mumol/L of As2O3 treated NB4 cells presented morphologically some features of apoptotic cells such as intact cell membrane, chromatin condensation and nuclear fragmentation. Sub-G1 cells, whose percentage presents concentration and time-dependency, were observed by flow cytometer. Otherwise, NB4 cells with the treatment of As2O3 at 0.1-0.25 mumol/L for a long time (10 days) have differentiation-related morphology, and their differentiation antigens CD11b and CD33 were also modulated to some extent. In addition, 0.1-2 mumol/L of As2O3 could rapidly and effectively modulate and degradate PML/PML-RAR alpha proteins. CONCLUSION: As2O3 had double effects (induction of apoptosis and imcomplete differentiation) on NB4 cells, which could associate with rapid modulation and degradation of PML/PML-RAR alpha proteins.

Antineoplastic Agents↗
PubMed1996

Longimicins A-D: novel bioactive acetogenins from Asimina longifolia (annonaceae) and structure-activity relationships of asimicin type of annonaceous acetogenins.

Bioactivity-directed fractionation of the ethanol extract of Asimina longifolia led to the isolation of four novel bioactive annonaceous acetogenins: longimicins A-D (1-4). Compounds 1-4 represent the asimicin type of acetogenins; however, the locations of the adjacent bis-tetrahydrofuran (THF) ring moieties are shifted along the aliphatic chains compared to the known compounds of this type. They are the first examples among this type of acetogenins with the placements of the ring systems altered. Compounds 1-4 showed bioactivities in several bioassays, but they are less active than their structural isomers. Study of their structure-activity relationships (SAR) reveals that the position of the adjacent bis-THF ring moiety is essential for maximization of the bioactivities among these asimicin type annonaceous acetogenins.

Animals↗
PubMed1996

Selective interaction of voltage-gated K+ channel beta-subunits with alpha-subunits.

To begin to study the molecular bases that determine the selective interaction of the beta-subunits of voltage-gated K+ channels with alpha-subunits observed in situ, we have expressed these polypeptides in transfected mammalian cells. Analysis of the specificity of alpha/bet a-subunit interaction indicates that both the Kvbeta1 and Kvbeta2 beta-subunits display robust and selective interaction with the five members of the Shaker-related (Kv1) alpha-subunit subfamily tested. The interaction of these beta-subunits with Kv1 alpha-subunits does not require the beta-subunit N-terminal domains. Thus, the previously observed failure of N-terminal mutants of Kv beta1 to modulate inactivation kinetics of Kv1 family members is not simply due to a lack of subunit interaction. Interaction of these beta-subunits with members of two other subfamilies (Shab- and Shaw-related) could not be detected. Somewhat surprisingly, a member of the Shal-related subfamily was found to interact with beta-subunits; however, this interaction had biochemical characteristics distinct from the beta-subunit interaction with Kv1 family members. In all cases, Kvbeta1 and Kvbeta2 exhibited indistinguishable alpha-subunit selectivity. These studies point to a selective interaction between K+ channel alpha- and beta-subunits mediated through conserved domains in the respective subunits.

Amino Acid Sequence↗
PubMed1996

Selectively cytotoxic diterpenes from Euphorbia poisonii.

Bioactivity-guided fractionation of the latex of Euphorbia poisonii Pax. (Euphorbiaceae) led to the isolation and characterization of a new tigliane diterpene, 12-deoxyphorbol 13-(9,10-methylene)undecanoate (3), together with five known diterpenes (1,2,4-6). When evaluated for cytotoxicity in a panel of six human solid tumor cell lines, the diterpene esters, 1-3, 5, and 6, were selectively cytotoxic for the human kidney carcinoma (A-498) cell line with potencies for 2 and 3 exceeding that of adriamycin by ten thousand times. Details of the isolations, structural analyses, and cytotoxic activities are described.

Adenocarcinoma↗
PubMed1996

cis-gigantrionenin and 4-acetyl gigantetrocin A, two new bioactive annonaceous acetogenins from Goniothalamus giganteus, and the stereochemistries of acetogenin 1,2,5-triols.

Using activity-directed fractionation, two new bioactive acetogenins, cis-gigantrionenin (1) and 4-acetyl gigantetrocin A (2), have been isolated from the bark of Goniothalamus giganteus (Annonaceae). Compound 1 has a cis-mono-THF ring with one flanking hydroxyl and possesses a cis-double bond at C-21/22 of the aliphatic chain; it represents only the second example of the cis-mono-THF ring annonaceous acetogenins having one flanking hydroxyl. Compound 2 has a trans-mono-THF ring with one flanking hydroxyl, but it possesses a mono-acetyl group at the 4-OH position; it represents only the second natural example of the acetylated annonaceous acetogenins; the first acetogenin reported, uvaricin, was mono-acetylated at the 24-OH. The stereochemistries of 1 and 2 were determined by the advanced Mosher ester method. In addition, the absolute stereochemistries of gigantriocin (3), gigantrionenin (4), and giganenin (5) were determined by the advanced Mosher ester method and by circular dichroism (CD). The stereochemistries of the 7,8-diols in murihexocins A (6) and B (7) were determined to have the S,S-configurations, respectively.

Animals↗
PubMed1996

Applying Mosher's method to acetogenins bearing vicinal diols. The absolute configurations of muricatetrocin C and rollidecins A and B, new bioactive acetogenins from Rollinia mucosa.

Muricatetrocin C (1), rollidecin A (2), and rollidecin B (3), three new bioactive annonaceous acetogenins bearing vicinal diols, were isolated from the leaves of Rollinia mucosa (Annonaceae) using activity-directed fractionation. The total structural elucidations of 1-3, including the absolute stereochemistries of the vicinal diols, were achieved by analyzing their per-Mosher ester derivatives. All three compounds showed potent and selective inhibitory effects against several human cancer cell lines.

4-Butyrolactone↗
PubMed1996

Beta subunits promote K+ channel surface expression through effects early in biosynthesis.

Voltage-gated K+ channels are protein complexes composed of ion-conducting integral membrane alpha subunits and cytoplasmic beta subunits. Here, we show that, in transfected mammalian cells, the predominant beta subunit isoform in brain, Kv beta 2, associates with the Kv1.2 alpha subunit early in channel biosynthesis and that Kv beta 2 exerts multiple chaperone-like effects on associated Kv1.2 including promotion of cotranslational N-linked glycosylation of the nascent Kv1.2 polypeptide, increased stability of Kv beta 2/Kv1.2 complexes, and increased efficiency of cell surface expression of Kv1.2. Taken together, these results indicate that while some cytoplasmic K+ channel beta subunits affect the inactivation kinetics of alpha subunits, a more general, and perhaps more fundamental, role is to mediate the biosynthetic maturation and surface expression of voltage-gated K+ channel complexes. These findings provide a molecular basis for recent genetic studies indicating that beta subunits are key determinants of neuronal excitability.

Animals↗
PubMed1996

Rollinecins A and B: two new bioactive annonaceous acetogenins from Rollinia mucosa.

Two new mono-THF ring acetogenins, rollinecins A (1) and B (2), were isolated from the partitioned ethanolic extracts of the leaves of Rollinia mucosa (Annonaceae) by activity-directed fractionation. 1 and 2 are epimeric at the C-14 carbinol stereocenter. Their absolute stereochemical structures were solved by preparing their respective per-Mosher ester derivatives. 1 and 2 showed equivalent and selective in vitro activities against several human solid tumor cell lines.

Antineoplastic Agents, Phytogenic↗
PubMed1996

Bioactive ent-kaurene diterpenoids from Annona senegalensis.

Activity-guided fractionation of the stem bark of Annona senegalensis gave four bioactive ent-kaurenoids (1-4). Compound 2 showed selective and significant cytotoxicity for MCF-7 (breast cancer) cells (ED50 1.0 microgram/mL), and 3 and 4 exhibited cytotoxic selectivity for PC-3 (prostate cancer) cells but with weaker potencies (ED50 17-18 micrograms/mL). The structure of the new compound, 3, was deduced from spectral evidence.

Africa↗
PubMed1996

Chlorinated annonaceous acetogenins and their bioactivities.

4(S)-Chloro-4-deoxygigantetrocin A and 4(S), 18-dichloro-4,18-dideoxyasimilobin were obtained by treating gigantetrocin A with triphenylphosphine and CCl4. The structures were determined by spectroscopic methods. The chlorinated compounds show decreased bioactivities in the brine shrimp lethality test and against human tumor cell lines.

4-Butyrolactone↗
PubMed1996

Three new adjacent bis-tetrahydrofuran acetogenins with four hydroxyl groups from Asimina triloba.

Three new adjacent bis-tetrahydrofuran ring Annonaceous acetogenins with four hydroxy groups, bullatetrocin (1), 10-hydroxyasimicin (2), and 10-hydroxytrilobacin (3), were isolated by activity-directed fractionation from the stem bark of Asimina triloba. Their structures were established on the basis of chemical and spectral evidence. The absolute stereochemistry at the C-10 hydroxy position was determined by converting 2 and 3 to their ketolactone isomers, 2,4-cis/trans 10-hydroxyasimicinones and 2,4-cis/trans 10-hydroxytrilobacinones, respectively. The bioactivities of the new compounds against brine shrimp larvae and six human solid-tumor cell lines are reported, and structure-activity relationships between trihydroxylated and tetrahydroxylated acetogenins are discussed. In addition to 1-3, gigantetrocin A, 2,4-cis/trans-gigantetrocin A-ones, annonacin, and annonacin A were also isolated for the first time from this species.

Animals↗
PubMed1996

Isolation of a new clathrin heavy chain gene with muscle-specific expression from the region commonly deleted in velo-cardio-facial syndrome.

Velo-cardio-facial syndrome (VCFS) and DiGeorge syndrome (DGS) are developmental disorders characterized by a spectrum of phenotypes including velopharyngeal insufficiency, conotruncal heart defects and facial dysmorphology among others. Eighty to eighty-five percent of VCFS/DGS patients are hemizygous for a portion of chromosome 22. It is likely that the genes encoded by this region play a role in the etiology of the phenotypes associated with the disorders. Using a cDNA selection protocol, we isolated a novel clathrin heavy chain cDNA (CLTD) from the VCFS/DGS minimally deleted interval. The cDNA encodes a protein of 1638 amino acids. CLTD shares significant homology, but is not identical to the ubiquitously expressed clathrin heavy chain gene. The CLTD gene also shows a unique pattern of expression, having its maximal level of expression in skeletal muscle. Velopharyngeal insufficiency and muscle weakness are common features of VCFS patients. Based on the location and expression pattern of CLTD, we suggest hemizygosity at this locus may play a role in the etiology of one of the VCFS-associated phenotypes.

Abnormalities, Multiple↗
PubMed1996

3p21 is a recurrent treatment-related breakpoint in myelodysplastic syndrome and acute myeloid leukemia.

In this study we report 11 cases with chromosome abnormalities involving 3p21. Nine cases were diagnosed as myelodysplastic syndrome (MDS), and two as acute myeloid leukemia (AML). Six of nine MDS cases were secondary to a primary malignant disease. In two patients, AML was secondary to breast cancer and polycythemia vera (PV). Seven of eleven patients had a history of intensive polychemotherapy and/or radiation therapy for 3.5 to 5 years. The mean interval from initial therapy to secondary disease was 13.2 years. Complex chromosomal aberrations were found in all 11 cases. Band 3p21 was involved in translocations in 9 patients and in deletions in 2 patients. A t(3;16)(p21;p13) was found in two cases. Additional abnormalities frequently included a -5, -7, as well as deletions or rearrangements of these 2 chromosomes. Data reported in this paper suggest that 3p21 is a recurrent treatment-related breakpoint in MDS and AML and is likely to contain a gene involved in the pathogenesis of this disease.

Acute Disease↗
PubMed1996

Mapping of 29 YAC clones and identification of 3 YACs spanning the translocation t(3;8)(p14.2;q24.1) breakpoint at 8q24.1 in hereditary renal cell carcinoma.

The constitutional balanced translocation (3;8)(p14.2:q24.1) has been described in a family in which a arge number of individuals developed renal cell carcinoma RCC) at an early age. The translocation event in which genes from the 3p14.2 and the 8q24.1 sites are brought in close proximity is considered a critical, initial step for the development and progression of RCC. Even though the 3p14.2 breakpoint region has been cloned, a gene has not yet been identified, which may be responsible for either the initiation or progression of hereditary RCC. As a crucial step toward cloning the 3;8 breakpoint at the 8q24.1 site, we have mapped a series of YACs which surround this region by fluorescence in situ hybridization (FISH). Three YACs have been identified that span the 8q24.1 breakpoint region. One of these YACs is approximately 180 kb in length, and has been used to initiate construction of a high resolution cosmid contig. Several cosmids have been isolated which have been positioned in relation to the 8q24.1 breakpoint region. In addition, we have positioned 26 other YACs in relation to the 3;8 translocation breakpoint. These results provide a basis for the isolation of genes surrounding 3;8 RCC translocation breakpoint region at 8q24.1.

Carcinoma, Renal Cell↗
PubMed1996

[Inhibitory action of Chinese compound prescription for reinforcing vital energy and invigorating blood circulation on cancer cell multiplication].

Experiments have proved that the Chinese compound prescription for reinforcing vital energy and invigorating blood circulation markedly helps to improve the morphology of cancer cell nucleolus and membrane surface microvillus, amend the composition of microtubulin and facilitate intercellular gap junctional communication. Cell cycle kinetics shows that the multiplication of cancer cells in human stomach is checked mainly at G2M stage.

Adenocarcinoma, Mucinous↗