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Biomedical subjects

Q Tian

Publications and source records attributed to Q Tian.

At least 55 records · Page 3Linked to original sources
PubMed1995

Vasodilator effect of human adrenomedullin(13-52) on hypertensive rats.

Human adrenomedullin (hADM) is a newly isolated peptide with hypotensive activity in normotensive rats. The objective of this study was to investigate the effect of hADM(13-52) on hypertensive animals. hADM(13-52) induced a dose-dependent decrease in the blood pressure of spontaneously hypertensive rats and renal hypertensive rats. This result suggests that hADM is a novel antihypertensive peptide. In isolated rat aortic arteries, hADM(13-52) produced nitric oxide dependent relaxation and inhibited endothelin 1 and angiotensin II release. These in vitro effects may represent the molecular mechanisms underlying the hypotensive action of hADM in vivo.

Adrenomedullin↗
PubMed1995

Constituents of the endolymphatic tubules as demonstrated by three-dimensional morphometry.

The various constituents of the tubules of the human adult intraosseous endolymphatic sac were stained with lectins and Millon reaction to reveal some of the carbohydrate and protein-containing substances in the endolymph. The amount of each substance was determined by digitizing sequential temporal bone sections. Differing amounts of the various identified substances were found in sacs from patients with Meniere's disease, patients with labyrinthine fibrosis, and controls.

Ear, Inner↗
PubMed1995

[A study on hypotensive mechanism of adrenomedullin (13-52)].

In the present study the hypotensive mechanism of AdM (13-52) was investigated in rats, both in vitro and in vivo. It was found that the hypotensive effect of AdM (13-52) could be partially inhibited by L-NG-nitro-arginine (LNNA), an inhibitor of nitric oxide synthase. The vasodilator effect of AdM (13-52) was dependent on vascular endothelium and inhibited by LNNA in a dose-dependent manner. This LNNA induced inhibitory effect could be reversed with L-Arginine. In addition, the vasodilator effect of AdM (13-52) disappeared with methylene blue (MB), which blocked cGMP formation. Using radioimmunoassay it was shown that LNNA lowered, but AdM (13-52) elevated the vascular cGMP content, while vascular cGMP content was not altered by co-application of AdM (13-52) and LNNA. The above results suggest that the vasodilator effect of AdM (13-52) might be mediated by nitric oxide.

Adrenomedullin↗
PubMed1995

[A kinetic study of hepatitis B virus pre-C gene mutation].

The point mutation in the precore region of hepatitis B viral genome (nt83) was tested with the method of mispairing PCR-RFLP in 54 chronic hepatitis B patients all confirmed by liver biopsy. The over all detection rate of pre-C mutation was 66.7% and the detection rate of pre-C mutation in chronic active hepatitis patients was as high as 80.0%, being significantly higher than that in chronic persistent hepatitis (46.7%). The detection rate of pre-C mutation was 41.2% in hepatitis B e antigen (HBeAg) positive group and 63.3% in anti-HBe(+) group respectively. The detection rate in anti-HBe(+) patients with normal alanine transaminase activity was as high as 82.4%. During the period of follow up it was found that pre-C mutation may appear and disappear or may persist continually. The results suggested that pre-C mutation was extremely common in chronic hepatitis B virus (HBV) infection. The coexistence of the mutant type and wild type in the patients may be considered as the natural course of HBV chronic infection. Further study on the cause and effect relation between pre-C mutation and genesis of chronic active hepatitis and liver cirrhosis is urgently needed.

Adult↗
PubMed1994

Intron-exon organization and chromosomal localization of the human TIA-1 gene.

TIA-1 is a 40-kDa cytotoxic granule-associated RNA-binding protein (p40-TIA-1), the expression of which is restricted to cytolytic lymphocytes. The major granule-associated species is a 15-kDa protein (p15-TIA-1) that seems to be derived from the carboxyl terminus of p40-TIA-1. Although some evidence suggests that p15-TIA-1 is derived from p40-TIA-1 by proteolytic processing, it is also possible that each isoform is derived from discrete mRNA initiated from alternative promoters within the TIA-1 gene. To learn more about the relationship between p15-TIA-1 and p40-TIA-1, we have determined the complete intron-exon organization of the TIA-1 gene. The gene consists of 13 exons separated by 12 intervening sequences and spans greater than 46 kb of DNA located on chromosome 2, band p13. The transcription start site of the mRNA transcript encoding p40-TIA-1 was identified by primer extension and S1 mapping analysis. The putative promoter region preceding this transcription start site stimulated the expression of a reporter gene in transfected Jurkat and YT cells. Attempts to identify a second promoter capable of initiating an mRNA encoding p15-TIA-1 were unsuccessful, supporting the possibility that p15-TIA-1 can be derived from p40-TIA-1 proteolytically. Granule-associated serine proteases that have been implicated in cytolytic lymphocyte killing (granzyme A and granzyme B) were unable to cleave TIA-1, suggesting that processing may occur before TIA-1 enters the cytotoxic granule.

Amino Acid Sequence↗
PubMed1994

Vagal-central nervous system interactions modulate the feeding response to peripheral enterostatin.

Enterostatin selectively inhibits the intake of dietary fat after both peripheral and central administration. We have investigated the role of the hepatic vagus nerve in modulating the peripheral response to enterostatin in Sprague-Dawley rats adapted to a high fat (HF) diet. Intraperitoneal (ip) enterostatin reduced intake of HF diet after overnight starvation. This response was abolished by selective vagal hepatic branch transection. Immunohistochemical techniques were used to identify the location of Fos protein in brain nuclei after ip enterostatin. Fos protein was evident in the nucleus tractus solitarius (NTS), parabrachial, paraventricular and supraoptic nuclei. The pattern of expression of Fos-like immunoreactivity differed from that induced by the lipoprivic agent beta-mercaptoacetate. Transection of the hepatic vagus blocked the central Fos responses to ip enterostatin. We conclude that afferent hepatic vagal nerve activity is required for the feeding response to peripheral enterostatin.

Animals↗
PubMed1994

Fibronectin-like immunoreactivity of the basilar membrane of celloidin-embedded human temporal bone sections.

Dysfunction of the mechanical properties of the basilar membrane is a potential cause of presbycusis. In cases of minimal sensorineural or strial degeneration it is believed to play a major role. The membrane has been shown to be partly composed of fibronectin. Fibronectin immunoreactivity is diminished in aged rats. Mesothelial cell line the perilymphatic surface of the membrane and are reduced in number in the aged rat cochlea. Fibronectin immunoreactivity was examined in human temporal bone sections (6 months to 92 years old). Hematoxylin and eosin stained section (17 to 97 years) were immunoreactivity was demonstrable in the human cochlea, but was not reduced, even in the eldest cases examined The number of mesothelial cells was reduced, however, and was related to the age of the individual, but not to the clinical diagnosis or audiogram shape. These two factors do not, therefore, appear to give rise to hearing losses associated with presbycusis.

Adolescent↗
PubMed1994

Identification of substances in the endolymphatic sac.

The composition of the contents of the endolymphatic sac (ES) has yet to be fully defined. Carbohydrates have been found in the ES of human fetuses and animals but not identified in the adult human ES. In the present study, celloidin was removed from previously prepared human temporal bone sections and a histochemical method was used to detect carbohydrates and protein in the ES. Six biotinylated lectins were used to identify specific carbohydrates in 15 ears: beta-D-N-acetylglucosamine, beta-D-galactose, D-galactose, alpha-D-mannose, D-N-acetylgalactosamine and alpha-L-fucose. The intensity of staining was graded qualitatively. A substance in the ES tubules that did not stain with any lectin was identified by the Millon reaction as containing protein. The carbohydrates and protein may exist in the different tubules or in the same tubule without mixing. This finding seems to support the idea that at least some of these substances are produced locally in the ES. Our observations support the hypothesis of the existence of a secretion and degradation system in the endolymphatic sac.

Carbohydrates↗
PubMed1994

[Studies on the components of trace elements and macro elements in hemolymph of Anopheles anthropophagus].

The elements in hemolymph of An. anthropophagus were determined by ICAP. There were 18 kinds of trace elements such as Fe,Zn,Cu,Mn,Cr,Mo,Co,Ni,V,Sr,B,Al,Ba,Zr, Cd,Pb,Ga,Li and 6 kinds of macro elements such as Ca,Mg,K,Na,S,P in the hemolymph of the mosquito. The contents of the macro elements and Fe in hemolymph of newly emerged mosquitoes were significantly higher than those of mosquitoes after taking blood meal, whereas Zn and Al were lower. Comparing elements in hemolymph of An. anthropophagus and An. sinensis, there were 14 kinds of elements in newly emerged mosquitoes with striking significant difference, while there were 13 kinds of elements with striking significant difference in the mosquitoes after taking blood meal. Comparing elements in the hemolymph of An. anthropophagus and Ae. albopictus, there were 13 kinds of elements with striking significant difference in the hemolymph of newly emerged mosquitoes and the mosquitoes after taking blood meal. The results suggested that the components of elements in hemolymph were relevant to the nutritional metabolism and development of mosquitoes, and that mosquitoes of different species and with different sensibilities to malaria parasites also showed difference in the contents of elements in their hemolymph.

Aedes↗
PubMed1992

Identification and functional characterization of a TIA-1-related nucleolysin.

We recently reported the molecular cloning of a cytotoxic granule-associated RNA-binding protein designated TIA-1. The ability of recombinant TIA-1 to induce DNA fragmentation in permeabilized cells suggested that this protein is the granule component responsible for inducing apoptosis in cytolytic lymphocyte (CTL) targets. Here we report the characterization of a cDNA encoding a TIA-1-related protein designated TIAR. The deduced amino acid sequence of TIAR reveals it to be a 42-kDa protein possessing three RNA-binding domains and a carboxyl-terminal auxiliary domain. Although the RNA-binding domains of TIA-1 and TIAR share greater than 85% amino acid homology, their carboxyl-terminal auxiliary domains are only 51% homologous. The carboxyl terminus of TIAR contains a lysosome-targeting motif, indicating that TIAR is probably a cytotoxic granule-associated protein. Like TIA-1, purified recombinant TIAR induced DNA fragmentation in permeabilized target cells. Although immunoblotting analysis of post-nuclear supernatants revealed TIA-1 protein to be restricted to CTLs, PCR analysis revealed the expression of TIA-1 and TIAR mRNA transcripts in a wide variety of cell types. Our data suggest that the granules of CTLs contain at least two candidate nucleolysins involved in CTL killing.

Amino Acid Sequence↗
PubMed1992

Purification, characterization and substrate specificity of rabbit lung phospholipid transfer proteins.

Three phospholipid transfer proteins, namely proteins I, II and III, were purified from the rabbit lung cytosolic fraction. The molecular masses of phospholipid transfer proteins I, II and III are 32 kilodaltons (kDa), 22 kDa and 32 kDa, respectively; their isoelectric point values are 6.5, 7.0 and 6.8, respectively. Phospholipid transfer proteins I and III transferred phosphatidylcholine (PC) and phosphatidylinositol (PI) from donor unilamellar liposomes to acceptor multilamellar liposomes; protein II transferred PC but not PI. All the three phospholipid transfer proteins transferred phosphatidylethanolamine poorly and showed no tendency to transfer triolein. The transfer of [14C]PC from unilamellar liposomes to multilamellar liposomes facilitated by each protein was affected differently by the presence of acidic phospholipids in the PC unilamellar liposomes. In an equal molar ratio of acidic phospholipid and PC, phosphatidylglycerol (PG) reduced the activities of proteins I and III by 70% (P = 0.0004 and 0.0032, respectively) whereas PI and phosphatidylserine (PS) had an insignificant effect. In contrast, the protein II activity was stimulated 2-3-times more by either PG (P = 0.0024), PI (P = 0.0006) or PS (P = 0.0038). In addition, protein II transferred dioleoylPC (DOPC) about 2-times more effectively than dipalmitoylPC (DPPC) (P = 0.0002), whereas proteins I and III transferred DPPC 20-40% more effectively than DOPC but this was statistically insignificant. The markedly different substrate specificities of the three lung phospholipid transfer proteins suggest that these proteins may play an important role in sorting intracellular membrane phospholipids, possibly including lung surfactant phospholipids.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1991

A polyadenylate binding protein localized to the granules of cytolytic lymphocytes induces DNA fragmentation in target cells.

Cytolytic lymphocytes (CTLs) are characterized by their inclusion of cytoplasmic granules containing effector molecules such as perforin and the serine proteases. Here we describe the cDNA cloning and functional characterization of two related isoforms of a cytolytic granule protein designated TIA-1. Sequence analysis reveals that the 40 kd TIA-1 isoform (rp40-TIA-1) is structurally related to the poly(A)-binding proteins, possessing three RNA-binding domains and a carboxy-terminal, glutamine-rich auxiliary domain. The 15 kd TIA-1 isoform, the major species present in cytolytic granules, appears to be derived from the carboxy-terminal auxiliary domain of rp40-TIA-1 by proteolytic processing. Both natural and recombinant TIA-1 were found to induce DNA fragmentation in digitonin permeabilized thymocytes, suggesting that these molecules may be the granule components responsible for inducing apoptosis in CTL targets.

Amino Acid Sequence↗
PubMed1991

Effects of azumolene on doxorubicin-induced Ca2+ release from skeletal and cardiac muscle sarcoplasmic reticulum.

The mechanism of doxorubicin-induced Ca2+ release from skeletal and cardiac muscle sarcoplasmic reticulum (SR) was studied by examining the effects of azumolene (a water soluble dantrolene analog) on doxorubicin-mediated Ca2+ release and ryanodine binding. Doxorubicin induced a rapid Ca2+ release from both skeletal and cardiac SR in a similar concentration range (EC50 = 5-10 microM). Maximal doxorubicin-induced Ca2+ release was seen at 2 and 0.2 microM Ca2+ for skeletal and cardiac SR, respectively. Addition of 400 microM azumolene caused approx. 30% inhibition of doxorubicin-induced Ca2+ release from both skeletal and cardiac SR; skeletal SR had significantly higher sensitivity to azumolene than cardiac SR. In the presence of Ca2+, doxorubicin increased [3H]ryanodine binding to both skeletal and cardiac SR; whereas in the absence of Ca2+, doxorubicin led to significant ryanodine binding to skeletal SR, but not to cardiac SR. In both types of SR, doxorubicin-activated, but not Ca2+ activated ryanodine binding was inhibited by azumolene. Azumolene sensitivity for inhibition of doxorubicin-activated ryanodine binding was much higher in skeletal SR than cardiac SR, consistent with the results for effects of azumolene on Ca2+ release. Our results are consistent with the possibility that azumolene inhibits doxorubicin binding by direct competition for the drug receptor(s).

Animals↗
PubMed1991

Vasoactive intestinal polypeptide (VIP) immunoreactive elements in the caudal ventral striatum of the rat: a light and electron microscopic study.

Under the posterior limb of the anterior commissure, a brain region intercalated between the ventral striatum and the ventral pallidum was previously identified as the interstitial nucleus of the posterior limb of the anterior commissure by de Olmos. This region, referred here as the caudal ventral stratum (VSc), is characterized by a dense plexus of vasoactive intestinal peptide immunoreactive (VIP+) axons. Double-fluorescence immunocytochemical reactions reveal that the dense VIP+ plexus is found in a region also rich in dopaminergic (i.e., tyrosine-hydroxylase immunoreactive) fibers but poor in enkephalinergic terminals. The dense plexuses of VIP+ axons in VSc appear to be contiguous with those in the bed nucleus of stria terminalis (BNST) and the central nucleus of amygdala (CNA). These results support the notion that this VSc region is a part of the "extended amygdala" as proposed recently by Alheid and Heimer, and confirms that its anatomical properties are closer related to the ventral striatum than the ventral pallidum. Electron microscopic analysis reveals that the VIP+ boutons form asymmetrical synapses with dendrites and spines, and symmetrical synapses with somata of unlabeled VSc neurons. The few VIP+ neurons within this area form synapses with many unlabeled axon terminals on both their somata and dendrites. Some VIP+ neurons, however, also form axosomatic and axodendritic synapses with VIP+ boutons.

Amygdala↗
PubMed1991

[Effect of electrical stimulation and lesion of N reticularis paragigantocellularis lateralis on acupuncture analgesia in rats].

The present study was aimed to investigate the role of the reticularis paragigantocellularis lateralis (RPGL) in acupuncture analgesia. Tail-flick response to electrical stimulation of the tail skin was taken as index of pain response. The first part of the study consisted of four groups: (1) surgical control, (2) electro-acupuncture, (3) electrical stimulation of RPGL, and (4) stimulation of RPGL simultaneously with electro-acupuncture. The pain threshold in the first group was quite stable during the experiments, but increased significantly after electro-acupuncture and/or brain stimulation (n = 14, P less than 0.01; n = 8, P less than 0.001; n = 14, P less than 0.001). The pain threshold of the fourth group increased much more than the second and the third group (P less than 0.001, P less than 0.01). In the second part of the study, the effect of electro-acupuncture was reduced significantly after electrical lesion of the RPGL unilaterally (n = 12, P less than 0.01). The present work indicates that electrical stimulation of RPGL enhances electro-acupuncture analgesia, whereas the lesion of RPGL reduces it. It is suggested that RPGL plays a role in acupuncture analgesia.

Acupuncture Analgesia↗