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Biomedical subjects

H Jin

Publications and source records attributed to H Jin.

At least 145 records · Page 8Linked to original sources
PubMed1997

Elimination of palmitoylation sites in the human dopamine D1 receptor does not affect receptor-G protein interaction.

We have eliminated putative palmitoylation sites in the carboxyl tail of the human dopamine D1 receptor by replacing the two cysteine residues with alanines either separately or together. The wild type and the three mutated dopamine D1 receptors were stably expressed in baby hamster kidney cells and characterized to detect any resulting alterations in receptor-G protein interactions. The three mutant dopamine D1 receptors retained the same proportion of high affinity state for agonists as wild type receptors and also no difference was observed in the stimulation of adenylyl cyclase activity. Our results are in contrast to those observed with the beta 2-adrenoceptor and consistent with similar studies of luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptors, alpha 2-adrenoceptors, muscarinic M2 receptors and thyrotropin releasing hormone (TRH) receptors. Thus, we suggest that palmitoylation appears to play a unique role in the beta 2-adrenoceptors, and appears not to be essential in G protein coupling for the dopamine D1 receptors.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1997

Influenza virus hemagglutinin and neuraminidase cytoplasmic tails control particle shape.

The cytoplasmic tails of the influenza virus glycoproteins hemagglutinin (HA) and neuraminidase (NA) are highly conserved in sequence for all virus subtypes and it is believed that assembly of this enveloped virus depends on interactions of these domains with cytoplasmic viral components. However, it is possible to rescue altered influenza viruses lacking either the HA or NA cytoplasmic tails. We have obtained an influenza virus that lacks both the cytoplasmic tail of HA and NA. Particle production is reduced approximately 10-fold but these particles, although having a fairly normal protein composition, are greatly elongated and of extended irregular shape. We propose a model in which the interactions of the cytoplasmic tails of HA and NA with an internal viral component are so important for spherical virion shape that there is dual redundancy in the interactions.

Amino Acid Sequence↗
PubMed1997

Synelfin regulation during the critical period for song learning in normal and isolated juvenile zebra finches.

Male zebra finches (Taeniopygia guttata) learn to sing during a critical period in adolescence. We previously described a presynaptic protein, synelfin, whose mRNA is increased early in this critical period in a brain nucleus specifically implicated in song learning, lateral MAN (lMAN). In the current study, in situ hybridization was used to map this change in gene expression to the subregion of lMAN that projects to the robust nucleus of the archistriatum (RA), the principal motor output of the telencephalic circuit that controls song production. Using confocal immunofluorescence microscopy, we detected numerous puncta of synelfin immunoreactivity that apparently represent presynaptic terminals from lMAN in the RA of young males. Synelfin immunoreactivity in RA declined abruptly between 40 and 45 days of age, a time of major synaptic reorganization in RA. This change did not occur until about 10 days after the decline in synelfin mRNA in cell bodies within lMAN, indicating a relatively slow turnover of the protein in presynaptic terminals and suggesting that some of the functional changes that occur during the critical period may arise from regulatory decisions that were initiated a week or more earlier. Depriving birds of tutoring did not halt or delay the decline of synelfin mRNA in lMAN. This change in gene expression must not be a consequence of early song learning, but may reflect an innate or programmed step in song circuit development.

Amyloid↗
PubMed1997

Localized changes in immediate-early gene regulation during sensory and motor learning in zebra finches.

A complex neural system controls birdsong learning, but its organization is not understood, nor is it known why learning only occurs during a critical period in adolescence. Here, we analyzed developmental regulation in zebra finches of zenk, an immediate-early gene (IEG) implicated in memory consolidation. Basal expression was elevated within auditory telencephalon (specifically, within the caudomedial neostriatum [NCM]) during song acquisition. Expression could be further induced by song playbacks 30 days after hatching but not at 20 days nor in juveniles reared in severe isolation. Singing itself induced zenk in song production nuclei, including Area X, even in adults. Within a compartment of the robust nucleus of the archistriatum (RA), however, this response dwindled as singing matured. These results suggest that the onset of sensory memory storage may be regulated in part at NCM, and motor plasticity may be regulated at RA.

Aging↗
PubMed1997

Nucleotide sequence of a 5423 base pairs fragment of the LsNPV genome and comparison with the AcNPV genome.

A 5423 bp fragment of LsNPV genome was sequenced, in which PDV-E66 gene and another four ORFs were found. The PDV-E66 gene of LsNPV was compared with the PDV-E66 gene of AcNPV, and a 51.9% nucleotide sequence homology and 38.8% amino acid sequence homology were found between the two genes. Two conserved late transcriptional motifs TAAG were found in LsNPV PDV-E66 gene, similar to those in AcNPV PDV-E66. The LsNPV PDV-E66 ORF is 204 base pairs shorter than the AcNPV PDV-E66 ORF at the 5' end. This is agreement with the fact that the N-terminus of the AcNPV PDV-E66 mature protein is 69 amino acids interior to the N-terminus predicted by the AcNPV PDV-E66 ORF. The 5' regulatory region of ORF1 contains early (CGTGC) and late (TAAG) transcriptional initiation motifs and ORF1 is predicted to encode a protein with 114 amino acid residues. The 5' regulatory region of ORF2 which can encode a protein with 115 amino acid residues contains only an early transcriptional initiation motif. Compared with all the genes from AcNPV and other baculoviruses, ORF1 and ORF2 have no homologous genes. It is suggested that ORF1 and ORF2 may be two novel baculovirus genes. ORF3 (PDV-E66 gene), ORF5 and an incomplete ORF, ORF6-part, have homologous regions in the AcNPV genome. ORF3, ORF5, ORF6-part are linked together in LsNPV genome, but their homologous regions are separated by about 58 kb fragment in the AcNPV genome. This fact indicates that the organization of the above genes in LsNPV is different from that of AcNPV. ORF4 is included in ORF6-part and can encode a 48 amino acid residues polypeptide, but ORF4 and ORF6-part are located on different DNA strands.

Amino Acid Sequence↗
PubMed1997

Inhibitory effects of efonidipine hydrochloride on contraction induced by several vasoconstrictors in porcine coronary artery: comparison with effects of nifedipine and nisoldipine.

We studied the effects of efonidipine hydrochloride (efonidipine), a 1,4-dihydropyridine derivative, on contractions induced by high-K+ solution (high K+), serotonin (5-HT), U46619, which is a stable analog of thromboxane A2, and endothelin-1 (ET-1) in comparison with those of nifedipine and nisoldipine in porcine coronary arteries. The effects of the drugs were compared after 1- and 3-h incubations. Efonidipine, nifedipine, and nisoldipine each inhibited the contractions induced by these vasoconstrictors. The inhibition of high-K(+)- and 5-HT-induced contractions by efonidipine, but not by nifedipine and nisoldipine, increased when the incubation time was prolonged, whereas the inhibition of U46619- and ET-1-induced contractions was not altered. The potency of efonidipine on U46619- and ET-1-induced contractions was greater than that of nifedipine and equivalent to that of nisoldipine. Thus the inhibitory effect of efonidipine on U46619- and ET-1-induced contractions seems to be stronger than its effects on high-K(+)- or 5-HT-induced contractions, in contrast to the effects of other dihydropyridines. In an additional series of experiments, efonidipine did not inhibit U46619-induced contractions in Ca2(+)-free solution or in the presence of nifedipine. Moreover, efonidipine did not inhibit the specific binding of [3H]SQ 29,548, a thromboxane A2 antagonist, to porcine coronary arterial membrane. Therefore we think that the inhibitory effect of efonidipine on contractions induced by vasoconstrictors was caused by blockade of Ca2+ influx through L-type Ca2+ channels. However, some unknown mechanism(s) in addition to this effect on Ca2+ channels may contribute to the effect of efonidipine on U46619- and ET-1-induced contractions.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1997

Hemodynamic effects of scatter factor in conscious rats.

Scatter factor (SF), also known as hepatocyte growth factor, is a potent mitogen that has been suggested to exhibit greater efficacy than vascular endothelial growth factor (VEGF) in rabbits with hindlimb ischemia. Our study examined the effects of SF on cardiovascular hemodynamics and compared the responses to VEGF. Hemodynamic parameters were monitored before and after administration of SF or VEGF in conscious, instrumented rats. Intravenous injection of SF produced a dose-related reduction in mean arterial pressure (MAP) and increase in heart rate (HR). These responses were significantly attenuated by pretreatment with N omega-nitro-L-arginine methyl ester a nitric oxide (NO) synthase inhibitor, suggesting the depressor effect of SF may be mediated by NO. SF (250 micrograms/kg) reduced stroke volume and cardiac output, but did not affect the maximal first derivation of left ventricular pressure (dP/dt), suggesting that the reduction in cardiac output is caused by decreased stroke volume that probably results from a reduction in venous return. Compared with SF, VEGF produced greater hypotensive and tachycardic responses and greater reductions in stroke volume and cardiac output, indicating that SF has fewer side effects on hemodynamics. Although both growth factors might reduce venous return, SF decreased hematocrit presumably through venodilation, whereas VEGF increased hematocrit as a result of vascular hyperpermeability.

Animals↗
PubMed1997

Spasmolytic effect of efonidipine hydrochloride in isolated canine coronary artery: comparison with the effects of nifedipine and nisoldipine.

Spasmolytic effects of efonidipine hydrochloride (efonidipine) on high K(+)-, U46619- and 3,4-diaminopyridine (3,4-DAP)-induced contractions were evaluated in isolated canine coronary, artery, and were compared with the effects of nifedipine and nisoldipine. Efonidipine (0.3-30 nM), nifedipine (1-300 nM) and nisoldipine (0.1-100 nM) each relaxed the contractions induced by high K+ and U46619. However, relaxation produced by efonidipine was slower than that produced by nifedipine or nisoldipine. The rank order of potency of these drugs for U46619-induced contraction was efonidipine > or = nisoldipine > nifedipine, whereas in high K(+)-induced contraction, it was nisoldipine > efonidipine > nifedipine. Thus, the relaxing effect of efonidipine on U46619-induced contraction appeared to be more potent than its effect on high K(+)-induced contractions, when compared with the effects of nifedipine and nisoldipine. These three drugs also suppressed 3,4-DAP-induced rhythmic contractions. However, a marked time-dependent increase in potency was only observed for efonidipine, and was similar to its time-dependent effect on high K(+)- and U46619-induced contractions. Efonidipine did not change the contraction cycle length whilst suppressing the peak contractions. On the other hand, lower concentration of nifedipine at 3 nM and nisoldipine at 1 nM significantly shortened the cycle length. These results suggest that efonidipine may be an effective agent for the treatment of angina pectoris. The high potency of efonidipine for U46619-induced contractions will provide some advantages in the clinical use of this compound on thromboxane A2-mediated coronary vasoconstriction.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1997

Differential screening of a subtracted cDNA library: a method to search for genes preferentially expressed in multiple tissues.

We have developed a new strategy for differential screening of genes that are expressed in two or more tissues, and have used it to identify genes that are preferentially expressed in both testis and ovary. In this approach, testis-specific cDNAs were first generated using the suppression subtractive hybridization technique, cloned and arrayed in microplates. The inserts from the subtracted testis-specific library were amplified by PCR and spotted on filters. The dot blots were screened by hybridization using either testis- or ovary-specific subtracted cDNA mixtures as probes. By screening about 2000 putative clones from the subtracted testis-specific library, we identified 14 candidate genes that hybridized to both cDNA probes. Northern blot analysis showed that 12 clones were preferentially or exclusively expressed in testis and ovary. Nucleotide sequence analysis indicated that three of the identified clones represented cDNAs from novel genes.

Animals↗
PubMed1997

Effects of advanced glycosylation end products on proliferation and cytosolic free calcium in cultured rat aortic smooth muscle cells.

AIM: To study the effects of advanced glycosylation end products (AGEP) on aortic smooth muscle cell (ASMC) proliferation and its relationship with cytosolic free calcium ([Ca2+]i). METHODS: The effects of AGEP modified bovine serum albumin (AGEP-BSA) on the incorporation of [3H]TdR and [3H]Leu into cultured ASMC were observed. The [Ca2+]i of cultured ASMC was determined with Fura 2-AM. RESULTS: AGEP-BSA stimulated the incorporation of [3H]TdR and [3H]Leu into ASMC in concentration and time-dependent manners (P < 0.01), especially [3H]TdR. In AGEP 200 mg.L-1 group, after 12-h exposure, the incorporation of [3H]TdR obviously increased, but DNA synthesis was concentration-dependently decreased in AGEP 300-400 mg.L-1 groups. The peak incorporation of [3H]TdR was 10 times vs control (P < 0.01). The [Ca2+]i of ASMC incubated with AGEP-BSA for 40 min was increased from control groups 121 +/- 4 to 492 +/- 20 nmol.L-1 (P < 0.01). [Ca2+]i induced by AGEP was elevated with the concentration and incubating time of glucose with BSA. [Ca2+]i in BSA incubated with glucose 80 mmol.L-1 for 12 wk was 580 +/- 37 nmol.L-1 (P < 0.01). CONCLUSION: AGEP stimulated proliferation of ASMC associated with the elevation of [Ca2+]i.

Animals↗
PubMed1997

[A comparative study of lanthanum, cerium and fluoride on the prevention of root surface caries by various procedure].

In order to evaluate the anticaries effects of several trace elements by combined and respective treating procedure, studies on inhibiting demineralization and improving remineralization were carried out with lanthanum, cerium and fluoride in a pH-cycling condition. The analysis of polarized microscope and electron microprobe demonstrated that the lanthanum and fluoride to an acetate buffer solutions had less severe demineralization of root surface than individual lanthanum or fluoride to the solution. The former, furthermore, precipitated a compound membrane which may be F-La(Ce)-Ca containing crystal on the root surface, and showed a better resistibility to acid. A further discussion was made from the viewpoint of crystal physiochemistry.

Adolescent↗
PubMed1997

[Preventive and therapeutic effects of radix Salviae miltiorrhizae on glycerol-induced acute renal failure in rats].

Three substances obtained from Radix Salviae Miltiorrhizae were administered to rats with acute renal failure (ARF) induced by intramuscular injection of glycerol. The rats treated with the substances had significantly lower serum urea and creatinine levels than the untreated animals. In the treated group, the survival percentage was higher than that in the untreated group. Examination of kidneys showed that the treated group had significantly lighter renal damage than the untreated group. These results suggest that the three substances exert preventive and therapeutic effects on the ARF in rats and the effects are probably the result of adenosine antagonism.

Acute Kidney Injury↗
PubMed1997

[Alkaloids in the seeds of Zyziphs jujuba Mill].

Two alkaloids were isolated from the seeds of Zyziphs jujuba and identified on the basis of spectral data to be lysicamine and juzirine. These two alkaloids were obtained from the genus for the first time.

Alkaloids↗
PubMed1997

[Significance of nm23 expression in malignant carcinoma of salivary gland].

In recent years, a tumor suppressor gene nm23 has been found to be associated with decreased tumor metastatic potential. Allelic deletion, mutation and low expression of this gene has been correlated with tumor metastatic potential in a number of tumors. We examined the expression of nm23 in 40 cases of salivary gland malignant carcinomas by immunohistochemical method. The results showed that nm23 lower expression tumors were associated with a higher rate of metastasis (81.8%) than nm23 higher expression (3.4%, P < 0.005). There is no correlation between nm23 lower expression and tumor size, location and pathologic type (P > 0.05). This result indicates that nm23 gene plays an important role in the metastasis of salivary gland malignant carcinoma.

Adult↗
PubMed1997

[The changes of lipid metabolism and hemorrheology in intrahepatic cholestasis during pregnancy].

OBJECTIVE: To identify the influence of the increased level of serum cholyglycine (CG) on lipid metabolism and hemorrheology in patients with intrahepatic cholestasis during pregnancy (ICP). METHODS: The concentrations of serum CG, total cholesterol (CH), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), high shear and low shear of blood specific viscosity (HS and LS), plasma specific viscosity (PV) and hematocrit (HCT) were measured in 68 cases of primiparas with single pregnancy and 30 healthy nonpregnant women respectively. The group of ICP was composed of 35 cases with CG > 6 mumol/L, the group of normal pregnancy, 33 cases with CG < 6 mumol/L. RESULTS: The means of CG and the lipidic parameters in the two pregnant groups were significantly higher than those in the non-pregnancy group (P < 0.02-0.001) except the means of HDL-C between the groups of ICP and non-pregnancy. The levels of LDL-C, LDL-C/HDL-C, LS, PV and HCT in the ICP were significantly higher than those in the normal pregnancy group (P < 0.02-0.001). CONCLUSIONS: There are significant changes of lipid metabolism and hemorrheology in patients with ICP. However, these changes could be corrected after pregnancy termination, when the level of serum CG returned to normal. The results suggest that the pathophysiologic changes of ICP are associated with increased level of serum CG.

Adult↗