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Biomedical subjects

Y Cai

Publications and source records attributed to Y Cai.

At least 199 records · Page 11Linked to original sources
PubMed1997

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) stimulate interleukin-6 production through the third subtype of PACAP/VIP receptor in rat bone marrow-derived stromal cells.

Regulation of Interleukin-6 (IL-6) production in bone marrow (BM)-derived stromal cells by neuropeptides, pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP), was examined. Both forms of PACAP, PACAP-27 and PACAP-38, as well as VIP significantly increased IL-6 production by rat BM-derived stromal cells at physiological concentrations ranging from 10(-10)-10(-8) M. The three related peptides (PACAP-27, -38, and VIP) stimulated the production of both cAMP and inositol 1,4,5-trisphosphate (IP3) in rat BM-derived stromal cells with similar 50% effective concentrations. The stimulatory potency of the three related peptides for the production of IL-6, cAMP, and IP3 was almost consistent, suggesting that the dual signaling transduction pathways may be involved in PACAP/VIP-induced IL-6 production in rat BM-derived stromal cells. The messenger RNA (mRNA) for the third subtype of PACAP receptor (PVR3) was found to be abundantly expressed in both BM-derived stromal cells and the BM tissue, whereas little of the mRNA for type 1 (PVR1) nor type 2 (PVR2) was detected. Furthermore, the mRNAs for PACAP and VIP were detected in the BM tissue, suggesting that both PACAP/VIP and PVR3 are synthesized in vivo in the BM. The results shown in this paper suggest that PACAP/VIP and their receptor play an important role in the IL-6 production and perhaps in the hematopoiesis in the BM.

Animals↗
PubMed1997

[Study on the chemotaxis and DNA synthesis of pulmonary artery smooth muscle cells].

OBJECTIVE: To explore the effect of hypoxia on the proliferation and migration of pulmonary vascular smooth muscle cells (PVSMC), and whether migration of PASMC is involved in the pathogenesis of pulmonary vascular remodeling associated with hypoxia. METHODS: In this study, the effect of PDGF, ANP and hypoxia on DNA synthesis and chemotaxis of cultured neonatal calf pulmonary artery smooth muscle cells (PASMC) is investigated by 3H-thymidine incorporation and measurement of cell migration using a 48-well Boyden chamber respectively. RESULTS: The results demonstrated that hypoxia could stimulate DNA synthesis and chemotaxis of PASMC induced by PDGF; ANP could inhibit DNA synthesis and chemotaxis of PASMC by a cGMP dependent pathway. CONCLUSIONS: It is suggested that PDGF, ANP and hypoxia play important roles in regulating the proliferation and migration of PASMC, which is important in the pathogenesis of hypoxic pulmonary vascular remodeling.

Animals↗
PubMed1997

[Role of endothelial-derived nitric oxide and its synthase in the development of hypoxic pulmonary hypertension in rat].

To clarify the role of endothelial-derived nitric oxide (EDNO) and its synthase (NOS) in the normal and hypertensive pulmonary vasculature, activity of endothelial NOS in the lungs, ENDO-dependent vasodilating response induced by bradykinin (BK), and cGMP content of lung tissue in normoxic and hypoxic rats were investigated. We also studied the effects of NOS inhibitor-L-NAME on the activity of NOS, cGMP content, mean pulmonary arterial pressure (mPAP) and carotid systolic arterial pressure (CAPs) in both rats. The results were as follows (1) In normoxic rats there was no NOS activity in the endothelium of small vessels (phi < or = 80 microns) and no relaxing response to BK. Long-term administration of L-NAME obviously inhibited the activity of ecNOS and cGMP content in the lungs of normoxic rats, therefore it led to the increment of CAPs but failed to elevate mPAP. (2) After hypoxic exposure for 10 days, NADPH-diaphorase (NADPH-d and ecNOS immunoreactivity turned to be positive in the endothelium of small vessels with diameter less than 80 microns. BK-induced EDNO-dependent vasodilation, the enzyme activity of cNOS and cGMP content in the lungs of hypoxic rats were significantly enhanced as compared with normoxic rats. Long-term administration of L-NAME in hypoxic rats markedly inhibited the enhancement of cNOS enzyme activity, the production of EDNO and cGMP content in rat lungs, consequently it significantly decreased mPAP but elevated CAPs obviously. These results suggest that the role of EDNO in maintaining the low basal tone of normal adult pulmonary circulation remain to be studied more precisely. The increased activity of ecNOS and the enhancement of EDNO synthesis might act to moderate the hypertension. The excess synthesis of EDNO might be toxic to the endothelium of pulmonary vessels, therefore potentiating the development of pulmonary hypertension.

Animals↗
PubMed1997

[Effect of experimental immunological otitis media on inner ear].

We observed the change of the Outer Hair Cell (OHC) of the Guinea Pig (GP) in experimental immunological otitis media under a transmission electron microscope. Animals were immunized systemically with Bovine Serum Album (BSA) until high circulation serum levels developed, then were given BSA 1 mg/0.1 ml transtympanic challenge into one middle ear (ME) cleft on four successive weeks, after the 7th day of the ME challenge GP were killed. Under the transmission electron microscope, we observed that of the degeneration of mitochondrion and thinning of the sub membranous cistern, the damage in the 3rd row of OHC is more severe than the 2nd and the 1st rows. It suggested that immune reaction of ME may have an effect on the inner ear.

Animals↗
PubMed1997

[Effect of L-arg and SNP on pulmonary arterial pressure and vascular structural changes of chronically hypoxic rats].

The effects of L-arginine (L-arg) and sodium nitroprusside (SNP) on pulmonary arterial pressure, the percentage of muscularization of intra-acinar vessels and ultrastructural changes of extra pulmonary artery and pulmonary arteriole of chronically hypoxic rats were studied. The results showed that: (1) Both L-arg and SNP decreased mean pulmonary arterial pressure of chronically hypoxic rats significantly. (2) Both L-arg and SNP reduced the percentage of muscularization of intra-acinar vessels of chronically hypoxic rats significantly. (3) Both L-arg and SNP protected pulmonary artery from the damages of endothelium and the changes in smooth muscle cell phenotype by hypoxia. These results suggested that exogenous nitric oxide might play a role in the protection of pulmonary arterial function and structure which alleviate the development of pulmonary hypertension induced by chronic hypoxia.

Animals↗
PubMed1997

[Effect of hypoxia on distribution and activity of nitric oxide synthase in rat lung].

Nitric oxide is an important cellular messenger molecule that has been implicated in a wide range of physiological and pathophysiological actions in cardiovascular, immune, and nervous systems. Nitric oxide synthase (NOS) is the sole and key enzyme responsible for the generation of nitric oxide. The effect of hypoxia-induced pulmonary hypertension on NOS in the lung is controversial. To clarify the effect of hypoxia on distribution and activity of NOS in rat lung, localization of NOS in the lungs of hypoxic and normoxic rats were studied using NADPH-diaphorase histochemical staining techniques, NOS enzyme activity in the lung homogenates was assessed by [3H] arginine to [3H] citrulline conversion. In the normoxic rat, NADPH-d was distributed in the endothelial cells of large pulmonary vessels (ID > 150 microns) and medium-sized (50 microns < ID < 150 microns) vessels but was not detected in the endothelium of small vessels (ID < 50 microns), and there was an absence of NADPH-d staining in the smooth muscle cells of small, medium, and large pulmonary vessels. However, after hypoxic exposure for two weeks, NADPH-d staining increased dramatically in the endothelial cells of large and medium-sized pulmonary vessels, and NADPH-d became markedly positive in the endothelial cells of small vessels. Hypoxia was also found to induce de novo NOS expression in the smooth muscle cells of small, medium-sized, and large pulmonary vessels. The enzyme activity of constitutive NOS(cNOS) was decreased obviously in the hypoxic rat lungs, but that of inducible NOS(iNOS) was increased significantly in the hypoxic rat lungs. These results suggested that the inhibited endothelium-derived relaxing factor (EDRF)/NO-dependent vasodilation after hypoxic exposure might be induced by decreased activity of cNOS in the endothelium of pulmonary vessels, and hypoxia-induced upregulation of iNOS expression and activity in the rat lung might play an important role in the adaptation of pulmonary circulation to hypoxia.

Animals↗
PubMed1997

[Perinatal monitoring in intrahepatic cholestasis of pregnancy].

The sensitivity of meconium stain in amniotic fluid for prediction of fetal well-being in intrahepatic cholestasis of pregnancy(ICP) was evaluated. The study consisted of an ICP group(n = 30), and a control group (n = 30) and the umbilical arterial pH value(< 7.2) was used as a standard. The positive and negative predicttive valus of meconium-stained amniotic fluid in ICP group were 80.0%; the positive and negative predictive values in control group were 60.0% and 92.0% respectively. There was no significant difference (P > 0.05) between the two groups in positive and negative predictive values. However, the positive and negative predictive values of the two groups were high, which indicated that meconium-stained amniotic fluid related to fetal hypoxia. Moreover, the incidence of meconium-stained amniotic fluid in ICP was higher than that in control (40.0%: 16.70%, P < 0.05). Therefore, we suggest that the amniotic fluid of patients with ICP should be observed very closely. When meconium-stained amniotic fluid is discovered, delivery by cesarean section is imminent.

Adult↗
PubMed1997

[Long-term results of preoperative chemotherapy for operable breast cancer].

OBJECTIVE: To evaluate the long-term therapeutic results of preoperative chemotherapy for operable breast cancer. METHODS: Patients were divided into preoperative chemotherapy group (group A, 253 cases) and postoperative adjuvant chemotherapy group(group B, 284 cases). The group A patients received preoperative chemotherapy for 4 weeks, followed by radical operation two weeks after chemotherapy. Postoperative adjuvant chemotherapy began within 2 weeks after surgery, with the same chemotherapeutic regimen for 6 or more cycles in both groups. RESULTS: (1) The 5-year overall survival rate (OS) and disease-free survival rate(DFS) were 59% and 54.9%, respectively, for group A in stage III, which were higher than those of group B(28.3% and 20.8%, P < 0.05). (2) For group A in stage II and III, the 8-year OS were 81.4% and 46.9%, and DFS were 76.3% and 40.6%, respectively, which were higher than those of group B(OS: 67.4% and 20.7%, DFS: 62.9% and 13.3%, P < 0.05). (3) The 5-year and 8-year OS were higher for group A than those for group B in patients with T3, T4 or positive nodes > or = 4, (P < 0.05). CONCLUSION: The results show that preoperative chemotherapy can improve the short- and long-term survival of patients with operable, stage III breast cancer and long-term survival of patients with stage II breast cancer.

Adult↗
PubMed1997

[The analysis of frontal facial soft tissue of normal native adult of han race of Guangdong province by using the computer assisted photogrammetric-system].

UNLABELLED: The authors analysed the feature of frontal facial soft tissue of 150 native adults of Guangdong province by using the computer assisted photogrammetric-system made by the authors, which contained several new mode parameters planed by the authors. THE RESULTS: 1. The mean measurements of six parameters (Sn-Mes, Gs-Mes, Exr-Exl, Enr-Enl. [symbol: see text]Zyr-Rc-Mes, [symbol: see text]Zyl-Lc-Mes.) of the male subjects were larger than those of the female subjects, and the mean measurements of two parameters (Zyr-Zyl/Gs-Mes, Rc-Lc/Gs-Mes) of the male subjects were smaller than the ones of the female subjects. 2. The four measurements (Tr-Mes, Gs-Sn, Zyr-Zyl, Chr-Chl) in both male and female subjects of Guangdong province were smaller than the ones of Sichuan and Shandong provinces, and one measurement (Tr-Gs) of Guangdong male subjects was also smaller than the one of Sichuan or Shandong province, and one measurement of Guangdong female subjects smaller than the one of Shandong province. The conclusions: 1. The normal native adults of han race of Guangdong province show sex-difference and region-difference in the feature of frontal facial soft tissue. 2. The new-mode parameters (such as: [symbol: see text]Zyr-RC-Mes, [symbol: see text]Zyl-Lc-Mes, Zyr-Zyl/Gs-Mes, Rc-Lc/Gs-Mes) are helpful in studying the feature of frontal facial soft tissue.

Adolescent↗
PubMed1997

[Cloning and expression of heavy- and light-chain variable region genes of monoclonal antibody specific for human fibrin].

OBJECTIVE: To obtain the minimum molecule having activity to bind human fibrin. METHODS: The immunoglobulin heavy- and light-chain variable region (VH and Vkappa) genes were isolated from 8E5 hybridoma cells, which secreted a monoclonal antibody against human fibrin, by RT-PCR. An expression vector pOPE51-8E5 was constructed for the recombinant VH-Vkappa expression. The transformed E. coli JM 109 cells were propagated and induced by IPTG. RESULTS AND CONCLUSION: Expression product was found in the periplasmic space and inclusion bodies by SDS-PAGE and immunobloting. It was a 30000 single chain fragment (scFv) with antigen-binding specificity. The yield of the scFv was 28.9% of the total bacterial proteins.

Animals↗
PubMed1997

[Reversed-phase high performance liquid chromatographic analysis of the unfolding procedure of bovine insulin].

A method for measurement of the dynamic unfolding procedure of bovine insulin by reversed-phase HPLC has been established. Insulin contains 51 amino acids and two intrachain disulfide bridges. The denaturation of bovine insulin was carried in dithiothreitol solution at 100 degrees C, and the equilibrium products were examined by HPLC at different reaction time. The results show that the conformation of insulin has changed before cleavage of the disulfide bonds to A and B chains. Bovine insulin, two intermediates and the reduction products A and B chains were well separated on a C18 column (4.6 mm x 150 mm) with a linear gradient elution of acetonitrile containing 0.1% trifluoroacetic acid. The conformation of the unfolding intermediates of insulin was indicated by chromatographic method, and the results were verified by matrix-assisted laser desorption ionization time of flight mass spectrometry. The method is helpful to reveal the conformation changes in the procedures of protein unfolding.

Animals↗
PubMed1997

Diffuse leiomyomatosis associated with X-linked Alport syndrome: extracellular matrix study using immunohistochemistry and in situ hybridization.

Inherited diffuse esophageal leiomyomatosis a benign tumor involving smooth muscle cells of the whole esophagus, is frequently associated with X-linked Alport syndrome, a hereditary disease of type IV collagen. Families with this condition are consistently found to have deletions encompassing the 5' ends of both the alpha 5 chain of type IV collagen (COL4A5) and the alpha 6 chain of type IV collagen (COL4A6) genes, always limited in COL4A6 to exons 1', 1, and 2. On the contrary, patients with COL4A5/COL4A6 deletions extending further into COL4A6 display no such tumors. Despite the deletion, a COL4A6 transcript including exon 4, but not exon 3, was found in a tumor sample, raising the possibility of the involvement of a truncated alpha 6(IV) chain in the tumorous process. Using immunohistochemistry and in situ hybridization methods, we analyzed the expression and distribution of the alpha 6 chain of type IV collagen in tumors in comparison with that of normal, fetal, and mature esophagus. We also studied associated changes in tumor basement membrane composition and in tumor-cell integrin subunit distribution. No labeling with alpha 6(IV) antibodies was detected in tumors, ruling out the hypothesis of a stably integrated truncated alpha 6(IV) chain in tumor basement membranes. In contrast, despite the deletions of the first two exons of the gene and its 5' end, a COL4A6 transcript is clearly expressed by tumor cells. This finding raises the question of a potential role for this RNA in the tumor process. The absence of the alpha 6(IV) chain is associated with the absence of the alpha 5(IV) chain, as was suggested by the COL4A5 deletion. An additional striking feature is the absence of the beta 1 chain of laminin in tumor basement membranes and the lack of or uneven expression of the alpha 5 integrin subunit. These findings show that dramatic changes in the composition of the matrix and the expression of integrin receptors also occur in this benign tumorous process.

Basement Membrane↗
PubMed1997

Role of macrophage colony-stimulating factor in atherosclerosis: studies of osteopetrotic mice.

Previous in vitro and in vivo studies have suggested that macrophage colony-stimulating factor (M-CSF) plays a role in atherogenesis. To examine this hypothesis, we have studied atherogenesis in osteopetrotic (op/op) mice, which lack M-CSF due to a structural gene mutation. Atherogenesis was induced either by feeding the mice a high fat, high cholesterol diet or by crossing op mice with apolipoprotein E (apo E) knockout mice to generate mice lacking both M-CSF and apo E. In both the dietary and apo E knockout models, M-CSF deficiency resulted in significantly reduced atherogenesis. For example, in the apo E knockout model, homozygosity for the op mutation totally abolished aortic atherogenesis in male mice and reduced the size of the lesions approximately 97% in female mice. Mice heterozygous for the op mutation also exhibited a significant decrease in lesion size. Among apo E knockout mice, the frequency of atherosclerosis in aortic arch was 0/6 (op/op), 1/15 (op/+), and 12/16 (+/+). The effect of the M-CSF on atherosclerosis did not appear to be mediated by changes in plasma lipoproteins, as the op mice exhibited higher levels of atherogenic lipoprotein particles. The effects of the op mutation on atherogenesis may have resulted from decreased circulating monocytes, reduced tissue macrophages, or diminished arterial M-CSF.

Animals↗
PubMed1996

Promotion of heat-induced apoptosis in FM3A cells by protease inhibitors.

Although it has been shown that proteases may play a positive role in in causing apoptosis of some cells, we report here that, on the contrary, protease inhibitors can promote heat-induced apoptosis in FM3A cells. Cysteine protease inhibitor, trans-Epoxy-succinyl-L-leucylamido-(4-guanidino)butane (E-64, 100 micrograms/ml) and aspartate protease inhibitor, pepstatin-A (100 micrograms/ml) were used to test hyperthermic effect on FM3A cells and showed remarkable cytotoxicity when they were present in cell suspension during heating at 44 degrees C. The cytotoxicity was due to promotion of heat-induced apoptosis as judged by DNA agarose electrophoresis. Furthermore, using flow cytometric analysis, we observed a decrease in the G0/G1 phase cell and an increase in the S phase cell as well as increased apoptosis after heat shock. E-64 and pepstatin-A exhibited a promotive effect on the changes of cell cycle induced by heat. The data presented suggest that the enhancement of hyperthermic cell killing by protease inhibitors may be related to promotion of heat-induced apoptosis and changes of cell cycle.

Animals↗
PubMed1996

Synaptic connections and interactions between area postrema and nucleus tractus solitarius.

The purpose of this study was to examine whether there are separate excitatory and inhibitory pathways from the area postrema (AP) to the nucleus tractus solitarius (NTS) and to examine the synaptic interactions between inputs from the AP and solitary tract (ST) on the NTS neurons. The following observations were made: (1) the predominant projections from the AP to the NTS were excitatory. Among the cells that had AP input, 90% of the cells (43/48) were excited by AP stimulation while 10% (5/48) of the cells were inhibited; (2) inputs from the AP and ST mainly summated occlusively on the NTS neurons, but at near threshold of discharge, the input from one source could facilitate the generation of action potentials induced by the other; and (3) single conditioning stimulation of the AP did not significantly inhibit the NTS neuronal response to ST stimulation, but stimulation of the AP with a train of high frequency stimuli inhibited the response of NTS neurons to ST stimulation and inhibited the evoked response to AP stimulation. The results of this study may help in the understanding of the modulatory role of the AP in the baroreflex and the integration process in the NTS.

Action Potentials↗
PubMed1996

PKD2, a gene for polycystic kidney disease that encodes an integral membrane protein.

A second gene for autosomal dominant polycystic kidney disease was identified by positional cloning. Nonsense mutations in this gene (PKD2) segregated with the disease in three PKD2 families. The predicted 968-amino acid sequence of the PKD2 gene product has six transmembrane spans with intracellular amino- and carboxyl-termini. The PKD2 protein has amino acid similarity with PKD1, the Caenorhabditis elegans homolog of PKD1, and the family of voltage-activated calcium (and sodium) channels, and it contains a potential calcium-binding domain.

Amino Acid Sequence↗
PubMed1996

delta Opioid receptor in neuronal cells undergoes acute and homologous desensitization.

Using delta opioid receptor as a model system, acute desensitization of neuronal opioid receptor was studied in detail in neuroblastoma x glioma NG108-15 cells and primarily-cultured mouse cortical cells. The opioid desensitization could occur in as short as 3 minutes of agonist treatment and the half-life of the desensitized state was about 90 minutes. This acute opioid desensitization was homologous in nature in both neuronal cells. The acute desensitization was almost abolished by treatment of the neuronal cells with staurosporine, a nonspecific protein kinase inhibitor. Treatment with the protein kinase C-selective inhibitor, calphostin C, however, caused partial block. In conclusion, neuronal opioid receptor undergoes acute, agonist-dependent, and homologous desensitization, during which protein kinases appear to play an important role.

1-Methyl-3-isobutylxanthine↗