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Biomedical subjects

Y Sun

Publications and source records attributed to Y Sun.

At least 955 records · Page 53Linked to original sources
PubMed1992

Determination of Na(+)-K(+)-ATPase alpha- and beta-isoforms and kinetic properties in mammalian liver.

While Western blot analysis clearly revealed the presence of the alpha- and beta-subunits of Na(+)-K(+)-ATPase in a variety of rat tissues, beta was not readily detectable in liver. This observation was consistent with a previous report indicating that Na(+)-K(+)-ATPase immunoprecipitated from rat liver gives no clear evidence for the presence of a beta-subunit (Hubert et al. Biochemistry 25: 4156-4163, 1986). However, Western blot analysis of density gradient-purified lamb and rat liver microsomes showed the presence of a protein with an approximate molecular mass of 42 kDa that was immunoreactive with beta-specific polyclonal antibodies as well as beta-directed monoclonal antibodies. Deglycosylation of this protein by N-glycosidase F generated a core protein (beta c, M(r) approximately 32,000) that had the identical electrophoretic mobility as the beta c protein of the purified kidney enzyme. Isoform-specific monoclonal and synthetic peptide-directed polyclonal antibodies were used to demonstrate the presence of only the alpha 1- and beta 1-proteins in the liver and the presence of beta 2 in rat brain. Functional studies then showed that although both rat and lamb liver enzymes had sensitivities to cardiac glycoside inhibition similar to that of their corresponding kidney enzyme, the lamb liver enzyme had higher affinities for Na+, K+, and ATP than the kidney enzyme.

Animals↗
PubMed1992

[A study on the decomposition kinetics of vitamin C tablet].

Under the condition of relative humidity less than the critical relative humidity, the discoloration rate and decomposition rate of vitamin C tablet and the discoloration rate of vitamin C tablet in solution were studied at temperatures 60-90 degrees C and relative humidities 60%-80%. The general equation of the relationship between the apparent rate constant k, absolute temperature T and relative humidity RH is: k = k' exp(-E/RT) exp(mRH), where k' and m are constants, E is apparent activation energy. The values of k', m and E for discoloration, decomposition and discoloration in solution are different.

Ascorbic Acid↗
PubMed1992

[The effects of early stage load-bearing on bone ingrowth of porous coated implant in rabbits].

To understand the effects of load-bearing on cementless fixation of porous coated implant, we inserted Co-Cr-Mo alloy implants into the distal femur of rabbits. Specimens were studied by means of histology, anti-collagen type I and III immunohistochemical staining, colloidal gold labeled immunoelectron microscopy, and computerized graphic analysis. The results revealed that stimulations of load-bearing benefited bone ingrowth, but the newly formed bone in the pores was absorbed and replaced by fibrous tissues after 12 weeks without stimulations of load-bearing. The fibrous tissues in the pores of the implant were primarily type III collagen after one week and type I collagen after two weeks. After 6 weeks, the residual tissue between ingrowth bone and metal bound antibodies was type I collagen. Fibroblasts participated in and possessed the action of osteogenesis.

Animals↗
PubMed1992

Depolarization increases vasoactive intestinal peptide- and substance P-like immunoreactivities in cultured neonatal and adult sympathetic neurons.

Depolarization has been shown to alter the biosynthesis of a number of neurotransmitters and neuromodulators. In the rat superior cervical ganglion (SCG), for example, depolarization has been reported to increase catecholamine biosynthesis and to decrease the level of substance P. We have recently found that, although the level of vasoactive intestinal peptide (VIP)-like immunoreactivity (IR) is normally low in the SCG, it increases significantly 48 hr after adult ganglia are deafferented in situ or placed in organ culture. Both manipulations decrease electrical activity of postganglionic neurons. To determine whether the increases in ganglionic VIP-IR could be a consequence of decreased depolarization of sympathetic neurons, the effect of depolarization on the expression of VIP-IR was examined in organ cultures of neonatal and adult SCG. Depolarization with elevated K+ (30 mM) or veratridine (1.5 microM) amplified, rather than blocked, the increases in VIP-IR content seen after 24 hr. Further, it increased the number of detectable VIP-IR neuronal cell bodies and processes. The stimulatory effects of veratridine were prevented by TTX. Since similar changes in expression of VIP-IR were evident in dissociated cell cultures of the SCG, cell-cell interactions requiring intact ganglionic architecture are not necessary for altered peptide expression. Elevating the concentration of Mg2+ blocked the ability of K+ and veratridine to increase VIP-IR in dissociated cell culture, raising the possibility that the effects of depolarization on VIP-IR are mediated by increased Ca2+ entry. The depolarizing conditions that increased VIP-IR also increased substance P-IR. While higher concentrations of veratridine (50 microM) blocked the elevation of both VIP- and substance P-IR induced by explantation, they produced significant neuronal death. Since depolarization with either 30 mM KCl or 1.5 microM veratridine increases expression of VIP-IR in neonatal and adult ganglia, decreased depolarization is unlikely to cause the increases in VIP- and substance P-IR that occur in culture. Furthermore, our data raise the possibility that sympathetic nerve activity in vivo can increase expression of these peptides.

Animals↗
PubMed1992

Preliminary report on seroepidemiology of HCV and HBV infection in northern China.

1 141 serum samples from various population groups in north China were examined for C100-3Ab by ELISA. Antibody to C100-3 antigen derived from HCV genome (C100-3A) and HBsAg were measured in 438 normal population in Beijing. The C100-3Ab positive rate was 2.1% and the HBsAg positive rate was 2.5%. There is increased occurrence with age. In 649 cases of chronic liver diseases, the HBsAg positive rate was 87.1% in chronic persistent hepatitis (CPA), 88.8% in chronic active hepatitis (CAH), 64.9% in liver cirrhosis (LC) and 67.3% in hepatocellular carcinoma (HCC). The C100-3Ab positive rate was 10.5% (CPH), 12.1% (CAH), 42.6% (LC) and 38.4% (HCC). It is noteworthy that the C100-3Ab positive rate significantly increased with disease progression from CPH to CAH, LC and HCC. Prevalence of cases positive for both C100-3Ab and HBsAg was 0% in the normal population, 6.7% in CPH, 8.4% in CAH, 31.1% in LC and 28.8% in HCC. Investigation of patients with HCV infection showed that only 36.8% had blood transfusions. HCV and HBV infection may play important pathogenic roles in CPH, CAH, LC and HCC in north China.

Adolescent↗
PubMed1992

[The use of 6-flavor Rehmannia decoction with additives in the prevention of ototoxic deafness induced by gentamicin in guinea pigs].

The purpose of this study is to discuss the effects of the Chinese medicine six-flavor Rehmannia Decoction with additives on preventing deafness induced by gentamicin (GM) in guinea pig by means of testing the thresholds of Preyer's reflex (PR) cochlear microphonic potential (CM), action potential of the auditory nerve (N1) and scanning electron microscope of inner ear (SEM). The results showed that the medicine is effective in reducing the ototoxic effect of GM on inner ear.

Action Potentials↗
PubMed1992

A simple method using PCR for direct sequencing of genomic DNA from frozen tumor tissue embedded in optimal cutting temperature compound.

Described here is a three-day protocol that directly yields DNA sequence after isolating and PCR amplifying genomic DNA from a small sample of frozen nasopharyngeal carcinoma tissue embedded in optimal cutting temperature (OCT) compound. The method is consistently successful, reproducible and will facilitate the rapid analysis of DNA sequence from very small samples.

Base Sequence↗
PubMed1991

Differentiation of isomeric conjugated bile acids using positive-ion B/E linked scans.

The main objective of this work was to use positive-ion fast atom bombardment mass spectrometry (FAB-MS) B/E linked scan spectra to investigate the possibility of differentiating positional isomers of various authentic glycine- and taurine-conjugated bile acids. Sodium salts of 14 conjugated bile acids were individually ionized by FAB-MS and characterized by scanning simultaneously the magnetic field B and the electric sector field E such that B/E remained constant throughout the scan. The dominant fragment ions could be related to cleavage of the aliphatic side chain with charge retention on the conjugated end of the bile acids. However, fragment ions arising from ring cleavages were also observed and could be used to distinguish the positions of substituent hydroxyl groups. For example, ring cleavage of conjugated dihydroxy bile acids at C-7/C-8 and C-9/C-10 permitted the differentiation of chenodeoxycholyltaurine (3 alpha,7 alpha-substitution pattern) from deoxycholyltaurine (3 alpha,12 alpha-substitution pattern) based on the presence of fragment ions at m/z 388 or m/z 404, which were indicative of hydroxyl group substitutions at either the 7- or 12-positions, respectively. It was concluded that B/E linked scans can be used to discriminate positional isomers of conjugated bile acids.

Bile Acids and Salts↗
PubMed1991

Isolation and partial characterization of a transformation-associated sequence from human nasopharyngeal carcinoma.

A transforming activity associated with Chinese nasopharyngeal carcinoma (NPC) cell line CNE2 DNA has been identified by transfer into nontransformed promotion-sensitive mouse JB6(P+) C141 cells. To clone this transformation-associated sequence, we carried out three cycles of transfection, followed by cloning of anchorage-independent transformants in soft agar. A tertiary CNE/JB6 clonal transfectant cell line 625 whose DNA showed transforming activity, as indicated in both soft-agar assay and nude-mice implantation, was used to make a genomic library in the vector lambda dash. Using the human repeated sequence Blur 8 to screen the library, we obtained 10 human Alu-positive clones. A cloned Alu-positive insert of 16 kbp, CNE 323, was characterized in detail. CNE 323 transferred moderate transforming activity when introduced into JB6 P+ cells and showed no homology to Ha-, Ki-, or N-ras genes; human promotion sensitivity genes; src, myb, jun, myc, fos, raf, or int-2 oncogenes; or epidermal growth factor receptor. The isolated CNE 323 DNA sequence appeared to preserve the genomic structure of the original sequence found in CNE2 cells and in nude mouse tumors induced by CNE2 cells or by CNE/JB6 transfectant cells, indicating that the cloned NPC sequence was activated during NPC carcinogenesis and not during transfection or construction of the library, and that the cloned sequence or a larger sequence of which it was part played a role in tumor formation. Finally, we identified a 1.3-kb mRNA that hybridizes to a subclone of the 16-kb NPC sequence in CNE2 cell poly (A)+ RNA.

Animals↗
PubMed1991

Reactivation of psoralen-reacted plasmid DNA in Fanconi anemia, xeroderma pigmentosum, and normal human fibroblast cells.

We have used a host cell reactivation system to study the effect of 8-methoxypsoralen (8-MOP) reaction on CAT (chloramphenicol acetyltransferase) and NEO (aminoglycoside phosphotransferase) expression in normal human cells, as well as two cell lines with possible DNA repair-processing defects. Plasmid DNA was treated with psoralen plus near-ultraviolet (NUV) irradiation. The reacted plasmids, pSV2cat and pSV2neo, were transfected into Fanconi anemia (FA), xeroderma pigmentosum (XP), and normal human fibroblast cells for transient or stable assay. The cells were assayed for CAT activity at various times after transfection or selected for G418 resistance. The extent of adduct formation required to inhibit expression was much less (difference of D37 greater than 2.5) in FA or XP cells compared to normal. We conclude that in FA and XP cells, the reactivation of CAT was much less than in normal cells. The possibility of differential DNA uptake and/or degradation in transient assay was ruled out by analysis of plasmid DNA recovered from transfected cells. The data of the two independent assays indicate that FA and XP cells are deficient in cross-linked DNA repair.

Cell Line, Transformed↗
PubMed1991

Seroepidemiology of HCV and HBV infection in northern China.

The HCVAb positive rate in normal population in Beijing was 2.1% and HBsAg positive rate was 2.5%. There is an increasing tendency in the aged group. Plasmapheresis might have been the major cause of HCV transmission in blood donors in the Hebei area. There was a high prevalence of HCVAb and HBsAg in chronic liver diseases in the Beijing area and the HCVAb-positive rate significantly increased corresponding to disease progression.

Adolescent↗
PubMed1991

Targeting radiopharmaceuticals--II. Evaluation of new trivalent metal complexes with different overall charges.

Three new multidentate ligands designed to have high affinity for Ga3+, In3+ and Fe3+ have been synthesized. N-(2-hydroxybenzyl)-N'-pyridoxylethylenediamine-N,N'-diacetic acid (HBPLED), N-(2-hydroxy-3,5-dimethylbenzyl)-N'-(3-hydroxy-1,2,5-trimethyl-4- pyridylmethyl)ethylenediamine-N,N'-diacetic acid (Me4HBPLED) and N,N'-bis(3-hydroxy-1,2,5-trimethyl-4-pyridylmethyl) ethylenediamine-N,N'-diacetic acid (DMPLED). These ligands give metal-ligand (M-L) complexes with (M = Ga3+, In3+, Fe3+) overall charges of -1.0 and +1, respectively. The 67Ga, 68Ga and 111In complexes of each of the three ligands and the 59Fe complex of Me4HBPLED were prepared, characterized and their biodistributions determined in rats after intravenous injection. Despite the differences in overall charge, the biological behavior of all three 111In complexes were similar, in that the radioactivity cleared rapidly via the kidney. The biodistributions of the 68Ga and 67Ga complexes were comparable to that of the 111In complex counterpart. Also, the 59Fe-Me4HBPLED biodistribution was not significantly different from those of the 68Ga- and 111In-Me4HBPLED. The renal clearance rate seems insensitive to the overall M-L charge; suggesting that the hydrophilic periphery of the ligand rather than the overall molecular charge determines the biological fate (with respect to renal clearance).

Animals↗
PubMed1991

Superoxide dismutase and catalase levels during estrogen-induced renal tumorigenesis, in renal tumors and their autonomous variants in the Syrian hamster.

Antioxidant enzyme levels were determined in kidneys during estrogen-induced cortical renal tumorigenesis in male Syrian hamsters. The activity of these enzymes in renal tumors were compared to those in the kidney cortex of untreated male castrated hamsters of different ages and in age-matched animals treated with diethylstilbestrol (DES) for varying periods. A transient increase in kidney Mn superoxide dismutase (MnSOD) and total SOD activity was seen after 1.5 and 3.1 months of DES treatment compared to untreated controls. However, after 4.4 months of DES exposure the activities of these antioxidant enzymes fell below untreated levels. The level of MnSOD and CuZnSOD was 3- to 10-fold lower compared to castrated male renal cortical values in DES-induced primary, serially transplanted and in autonomous renal tumour variants. Catalase activity declined steadily at 1.5 to 4.4 months of DES treatment. Low levels of catalase activity were found in all tumors examined. In general, Western blot analysis of immunoreactive proteins confirmed these findings, indicating that the low enzyme activities were due to low levels of enzyme proteins. Immunohistochemistry of the earliest tumor foci exhibited negligible antioxidant enzyme activity. The levels of these antioxidant enzymes were similar in all tumors surveyed, both primary and autonomous variants and in newborn kidneys, and they were about 10-fold lower than in normal kidney cortex or isolated proximal tubules.

Animals↗
PubMed1991

Angiotensin converting enzyme inhibition in heart, kidney, and serum studied ex vivo after administration of zofenopril, captopril, and lisinopril.

Angiotensin converting enzyme inhibition in heart, kidney, and serum were studied ex vivo after oral administration of lisinopril (10 mg/kg), zofenopril (10 mg/kg), and captopril (30 mg/kg) to rats to study the time course, degree, and sites of inhibition of ACE by a quantitative in vitro autoradiography and enzymatic assay. ACE activity in all regions of the heart, kidney, and serum was markedly reduced 4 h after administration of lisinopril and zofenopril and only partially recovered toward control levels at 24 h. After captopril treatment, ACE activity was partially inhibited in heart, kidney, and serum at 1 h and fully recovered toward control levels in most regions at 24 h. These results suggest that these inhibitors reduce ACE in all regions of the heart and kidney without regional selective inhibition. Lisinopril and zofenopril at these doses produced longer-lasting ACE inhibition than captopril. ACE recovery after ACE inhibitor treatment in serum was faster than in heart or kidney.

Angiotensin-Converting Enzyme Inhibitors↗