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Biomedical subjects

Y Ren

Publications and source records attributed to Y Ren.

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

Causal role for jun protein in the stimulation of choline acetyltransferase by insulin in embryonic chick retina.

Previous work showed that the availability of insulin to the embryonic chick retina at a critical developmental stage stimulated the activity of the acetylcholine synthetic enzyme, choline acetyltransferase (ChAT) (R. E. Hausman et al., 1991, Dev. Brain Res. 59, 31-37). Here we show that a 2- to 5-min exposure to insulin results in a greater than 24 hr elevation in ChAT protein. Immediately following exposure to insulin there is a transient increase in the level of jun protein followed by an increase in ChAT. The stimulation of ChAT protein is not the result of an overall stimulation of protein synthesis as other proteins are not affected. Exposure of the cells to antisense oligonucleotide to jun, but not to sense oligonucleotide, reduces the increase in both jun and ChAT. These and previous results suggest that insulin is necessary for the characteristic increase in ChAT protein during retina development and that this increase requires the transient synthesis of jun.

Animals↗
PubMed1997

Asymmetrical protection of neostriatal neurons against transient forebrain ischemia by unilateral dopamine depletion.

Neurons in the dorsal neostriatum are highly vulnerable to transient cerebral ischemia. It has been suggested that excessive dopamine release during ischemia may play an important role in the pathogenesis of postischemic cell death in the neostriatum. However, it remains controversial whether depletion of dopamine protects neurons in the neostriatum against ischemic insult. In the present study, transient forebrain ischemia was induced using the four-vessel occlusion method. Ischemic depolarization was used as an indication of completed ischemia. Under our experimental conditions, ischemia that produces approximately 21 min ischemic depolarization caused more than 90% of cell death in the dorsolateral neostriatum. Using such ischemia as a standard insult, the effect of dopamine depletion on neostriatal neurons after ischemia was investigated. Dopamine depletion was produced by unilateral injection of 6-OHDA into the substantia nigra. No difference was found between the number of surviving neurons in the left and the right neostriatum after depletion of dopamine on the left side. In contrast, surviving neurons dramatically increased in the right neostriatum after depletion of dopamine on the right side. These results clearly demonstrate an asymmetrical protection of neostriatal neurons against ischemia after dopamine depletion. The mechanisms of this asymmetrical protection may clarify dopamine action on neuronal injury following cerebral ischemia.

Animals↗
PubMed1997

Human proliferation-related protein p120 interacts with HSRP1.

Protein p120 is a proliferation-related nucleolar protein, which is detectable early in the G1-phase of the cell cycle and peaks early in the S-phase. Most human malignant tumor cells contain much higher levels of protein p120 than do normal resting cells. To learn more about p120-associated proteins, a yeast two-hybrid screen was carried out using protein p120 as the bait. Five positive clones were identified from 2 million clones for further analysis. Three of them encoded portions of the same protein, which had identity to human SRP1. The recombinant p120 and HSRP1 proteins produced in Sf9 cells are associated with each other, confirming the results of the yeast genetic assay. Protein SRP1 was originally characterized as a suppressor of RNA polymerase I mutations, and recently human SRP1 was identified as a receptor for nuclear localization sequences. In the present study, use of deletion mutations revealed that the binding of human SRP1 to p120 required the p120 nuclear localization signal (amino acids 96-119) and the C-terminus of human SRP1 (amino acids 453-491).

Animals↗
PubMed1997

[Drilling decompression of the proximal tibia for osteoarthritis of the knee].

OBJECTIVE: To investigate the effect of drilling decompression of the proximal tibia for the Osteoarthritis of the Knee. METHOD: The drilling decompression of the proximal tibia were performed in 21 patients (38 knees) of osteoarthritis with 99mTc-MDP scintingraphy and the intraosseous phlebography made pre-postoperatively. Knee function scores and scales were evaluated. RESULT: During 6-12 months follow-up, the preoperative score of the knee function was 18-48 (average 30.78) and the postoperative score was 61-96 (average 87.95); the rates of fair and good of knee scales rose from 5% preoperatively to 86.84% postoperatively. CONCLUSION: Drilling decompression of the proximal tibia is a simple, safe, less traumatic and effective method to relieve the pain and improve the function for the early osteroarthritis of knee, For late cases it is a method to relieve pain. 99mTc-MDP scintingraphy can be used as a method to diagnose the early stage of the osteoarthritis.

Adult↗
PubMed1997

[Synthesis and antiarrhythmic activity of some (erythro)-phenylpropanediolamine compounds].

For the purpose of searching for new drug with high potency and simple chemical structure, the dominant conformation and structural parameters of Guan-Fu base (GFA) molecule were modelled and calculated with a SGI-4D 25G computer. The propanediolamine chain in GFA might be considered to be a pharmacophore responsible for the bioactivity and the configuration of the chain seemed important. Thus, thirteen compounds of (erythro)-p-x-PhCHOHCHOHCH2NHR(x = H, I1-7; X = NO2, II1-6) were prepared. Among them, 10 compounds showed antiarrhythmic effect on aconitine-induced arrhythmia in rats. The ED50(to stop VT) of I2 and ED50(to stop VP) of I3 were shown to be comparable with those of GFA. In the synthesis, no stereoselectivity was found in the Prevost reaction with allylamine analogues (a1-7). After a1-7 were acetylated, the erythro type products(I1-7) were obtained.

Aconitine↗
PubMed1997

[Determinaion of artificial synthetic pigment in the drug by reflection spectrophotometry].

Solid phase spectrophotometry is a new, simple, fast and sensitive trace analytical method. In this report, it is presented a method that the polyamide was used for the absorbence and the reflectances absorbances were measured directly with remodelled the colorimetric cell. Not only the trace inorganic ion can be analysed by the solid phase method, but also the artificial synthetic pigment in the drug can be determined, the results are satisfied.

Coloring Agents↗
PubMed1997

[Nondectructive analysis of liquid samples with near-infrared spectroscopy].

This paper studied the near-infrared spectra of liquid samples. The plots of weights at each wavelength showed the spectral characteristics of pure materials. The samples could be classified by using plots of the scores of their first principal components. The principal component regression of samples was made. The obtained results were identical with the reference analytical values. The advantages of near-infrared spectroscopy, combined with principal component analysis, lie in its nondectructivity for samples and suitability for on-line measurements.

English Abstract↗
PubMed1997

Heterogeneity of angiotensin action in renal circulation.

Reported concentrations of angiotensin II (Ang II) in renal interstitial fluid are as high as 10 nM. Despite such high concentrations, intrarenal arterial infusion of Ang II at rates that induce far less change in renal Ang II concentration still elicits renal vasoconstriction. We examined whether the glomerular afferent arterioles (Af-Art) was more sensitive to intraluminal than extraluminal Ang II in superficial or juxtamedullary nephrons. Rat superficial Af-Arts with the intact glomerulus were microdissected and perfused in vitro at 70 mmHg, while juxtamedullary Af-Arts were visualized in isolated perfused kidneys (at 100 mm Hg) according to the method of Casellas and Navar. Increasing doses of Ang II (1 pM to 10 nM) or norepinephrine (NE; 1 nM to 1 microM) were added to either bath (extraluminal) or arteriolar perfusate (intraluminal). Decreases in luminal diameter induced by Ang II were significantly larger with intraluminal than extraluminal administration in superficial Af-Art: at 100 pM the diameter decreased by 52 +/- 8% (N = 6) and 7 +/- 3% with intraluminal and extraluminal administration, respectively. In contrast, in the juxtamedullary Af-Arts intraluminal and extraluminal Ang II caused similar constriction. On the other hand, there was no difference in intraluminal versus extraluminal NE action in either superficial or juxtamedullary nephrons. In conclusion, glomerular Af-Arts seem to have a higher sensitivity to luminal than interstitial Ang II in superficial but not juxtamedullary nephrons. Such heterogeneities in Ang II action may be important in the control of glomerular hemodynamics under various physiological and pathological conditions.

Angiotensin II↗
PubMed1996

Genomic organization and promoter function of the human thyrotropin-releasing hormone receptor gene.

We isolated and characterized the gene for the human thyrotropin-releasing hormone receptor. The gene spanned more than 30 kilobases and contained three exons and two introns. Intron 1 exists in the 5'-untranslated region, and intron 2 is more than 25 kilobases in length which interrupts the coding region before the beginning of the putative sixth transmembrane domain. Exon 3 encodes the rest of the coding region and the entire 3'-untranslated region. The 3'-flanking region contains four potential polyadenylation signals, and 3'-rapid amplification of cDNA ends studies showed that only a signal at 2076 base pairs downstream of the stop codon was functional in the anterior pituitary. Primer extension and anchor-polymerase chain reaction studies indicated a transcriptional start site at 344 base pairs upstream of the translational start site. The promoter region does not contain either a TATA box or a CAAT box in the appropriate location. Transient transfection study revealed significant activity of the promoter in GH4C1 cells, and the region between -338 and -933 bp from the transcriptional start site worked as a negative regulator. Knowledge of the genomic organization and the promoter region of thyrotropin-releasing hormone (TRH) receptor gene will allow further studies of possible disorders of the TRH receptor, as well as facilitate elucidation of transcriptional control of the human TRH receptor gene.

Amino Acid Sequence↗
PubMed1996

Identification of a domain (155-183) on CD36 implicated in the phagocytosis of apoptotic neutrophils.

Clearance of apoptotic neutrophils by macrophages is a crucial event following the resolution of acute inflammation. CD36, together with alphavbeta3, has been identified as one of the adhesion molecules on the surface of macrophages implicated in the clearance of polymorphonuclear leukocytes. The domain on CD36 implicated in the phagocytosis of aged neutrophils remains to be elucidated. In this study, COS cells transfected with human CD36 cDNA had a significantly higher capacity to phagocytose human apoptotic neutrophils compared with murine CD36 cDNA. Moreover, monoclonal antibodies 10/5 or OKM5 (epitopes identified on amino acids 155-183) but not monoclonal antibody 13/10 (epitope identified on amino acids 30-76) inhibited phagocytosis of apoptotic neutrophils by COS cells transfected by human CD36. Swapping the human CD36 155-183 domain from human to murine CD36 (human-murine CD36 chimera) imparted to murine CD36-transfected COS cells an increased capacity to phagocytose apoptotic neutrophils. Conversely, when the murine domain 155-183 was inserted in human CD36, a decreased phagocytic capacity was observed. In addition, a synthetic peptide(155-169) but not its scrambled form significantly inhibited phagocytosis. These results identify for the first time a functional domain encompassing amino acids 155-183 on human CD36 implicated in the recognition and phagocytosis of apoptotic neutrophils.

Animals↗
PubMed1996

Overexpression of human nucleolar proteins in insect cells: characterization of nucleolar protein p120.

Nucleolar p120 is a proliferation-associated protein, which becomes detectable early in the G1 phase of the cell cycle and peaks early in the S phase. A variety of human malignant tumor cells contain much higher levels of p120 than normal resting cells. The cellular functions of p120 are unknown, and little information is available on the structural characteristics of the human p120 protein. For biochemical characterization, human p120 protein was expressed in a baculovirus system and purified to approximately 95% purity. By indirect immunofluorescence, most of the recombinant human p120 as well as recombinant human B23, C23, or fibrillarin were localized to insect cell nucleoli and to large globular nuclear inclusions. Like endogenous p120 in HeLa cells, recombinant p120 expressed in insect cells was phosphorylated. On sucrose density gradients, p120 from HeLa cells sedimented in the 60-80S region, in which preribosomal particles sedimented using similar extraction and centrifugation procedures. The sedimentation of p120 shifted to the 5-10S region by treatment with 1 M KCl or with RNAse which suggests that p120 is bound to RNA.

Amino Acid Sequence↗
PubMed1996

Semipreparative chromatographic separation of cyclosporin G metabolites generated by microsomes from rabbits treated with rifampicin.

An efficient drug-induced rabbit liver microsomal enzyme system, that may be easily scaled up, has been applied to produce milligram (mg) quantities of cyclosporin G metabolites (CMs). Using hepatic microsomal preparations from rabbits pretreated with rifampicin (RIF) and a NADPH regenerating system, we converted 60% of the cyclosporin G (CsG) to 12 CMs in 2 hr. CMs were recovered by solid-phase extraction. Separations performed on a semipreparative scale with two sequential 250 x 10 mm reversed-phase HPLC columns yielded mg quantities of CMs. The yield of GM1 and GM9 obtained by a single HPLC separation step was estimated to be 1585 +/- 103 micrograms and 648 +/- 33 micrograms, respectively. Other CMs produced by this microsomal enzyme system were GM19, GM4N, GM1c, the aldehydic isomers (GM1cAL and GM1AL), GM14N, GM4N9, GM1A, and GM1cA. The purity of CMs was confirmed by analytical HPLC and their molecular weights (M.W.) were determined by Fast Atomic Bombardment Mass Spectrometry (FABMS). Biotransformation of CsG and cyclosporine (CsA) was also compared using this in vitro model system. Significant difference was found between the rate of aldehydic metabolite formation from CsG and that from CsA. This translates to a faster rate of AM1cAL and AM1AL formation than that of GM1cAL and GM1AL. In addition, the rate of CsG conversion to GM9 appears to be faster than that of CsA conversion to AM9.

Animals↗