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Biomedical subjects

Y Su

Publications and source records attributed to Y Su.

At least 217 records · Page 12Linked to original sources
PubMed1991

Effects of glucose, insulin, and cAMP on transcription of the serine dehydratase gene in rat liver.

Starvation and diabetes both caused a dramatic induction of hepatic L-serine dehydratase (SDH) (EC 4.2.1.13) in rats. Increases in the activity of the enzyme which had been demonstrated in several previous studies were found to be associated with increases in the amount of SDH protein and its mRNA in our studies reported herein. Nuclear run-on experiments with isolated liver nuclei demonstrated that the increases in SDH activity were mainly the result of increases in the rate of SDH gene transcription. Refeeding of glucose to starved rats or the administration of insulin to diabetic rats caused a marked reduction in the amount of SDH mRNA. The rates of transcription as measured in isolated nuclei were reduced to uninduced levels within 30 min of either treatment. Following the administration of Bt2-cAMP, the transcription rates of the SDH gene returned to the original induced rates within 40 min both in glucose-refed rats and in diabetic rats administered insulin. The results of these experiments indicate that the induction of SDH in rat liver in vivo is controlled predominantly at the level of gene transcription by the reciprocal action of cAMP and insulin.

Animals↗
PubMed1991

Altered phosphorylation of tau protein in heat-shocked rats and patients with Alzheimer disease.

Six hours after heat shocking 2- to 3-month-old male and female Sprague-Dawley rats at 42 degrees C for 15 min, we analyzed tau protein immunoreactivity in SDS extracts of cerebrums and peripheral nerves by using immunoblot analysis and immunohistochemistry with the anti-tau monoclonal antibody Tau-1, which recognizes a phosphate-dependent non-phosphorylated epitope, and with 125I-labeled protein A. In the cerebral extracts, we found altered phosphorylation of tau in heat-shocked females, characterized by a marked reduction in the amount of nonphosphorylated tau, a doubling of the ratio of total (phosphorylated plus nonphosphorylated) tau to nonphosphorylated tau, and the appearance of the slowest moving phosphorylated tau polypeptide (68 kDa). Similar, but milder, changes were observed in male rats. These changes progressively increased in females from 3 to 6 h after heat shocking. In contrast, both phosphorylated tau and nonphosphorylated tau were reduced in peripheral nerves after heat shocking. In immunoblots of SDS extracts from Alzheimer disease-affected brain, the two slowest moving phosphorylated tau polypeptides (62 kDa and 66 kDa, respectively) were detected by Tau-1 after dephosphorylation and by Tau-2 (an anti-tau-monoclonal antibody that recognizes a phosphate-independent epitope) without prior dephosphorylation only in regions that contained tau immunoreactivity in histologic preparations. In addition, quantitative immunoblot analysis of cortex and the underlying white matter with Tau-1 and 125I-labeled protein A showed that the amount of phosphorylated tau progressively increased in the Alzheimer disease-affected cerebral cortex, while concurrently a proportionally lesser amount of tau entered the white matter axons. The similar findings for the rat heat-shock model and Alzheimer disease suggest that life stressors may play a role in the etiopathogenesis of Alzheimer disease.

Alzheimer Disease↗
PubMed1991

Hormonal regulation of serine dehydratase gene expression in liver and kidney of the adrenalectomized rat.

We have previously demonstrated that glucagon but not dexamethasone could induce serine dehydratase (SDH: EC.4.2.1.13) in liver, and either glucagon or dexamethasone could induce the enzyme in kidney of normal rats. The mechanism(s) of the hormonal regulation of SDH gene expression in liver and kidney was further studied using adrenalectomized rats. Simultaneous administration of glucagon and dexamethasone induced the activity, rate of SDH synthesis, and accumulation of SDH mRNA in both liver and kidney of the rat. The increased SDH activity was reflected by changes in the amount of enzyme protein and in the rate of SDH protein synthesis, both parameters closely paralleling the changes in the levels of SDH mRNA. The rates of transcription of the SDH gene as measured in run-on experiments with isolated nuclei were also increased by the administration of these hormones. These results indicate that the expression of the SDH gene was regulated primarily at the transcriptional level under these conditions. When glucagon or dexamethasone was injected separately into adrenalectomized rats, significant increases in the levels of SDH mRNA and the rate of SDH gene transcription were observed in liver. Although glucagon was more effective than dexamethasone, both hormones were required for the maximal induction of SDH gene transcription in liver. In contrast, dexamethasone alone effectively increased the rate of SDH gene transcription in kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗
PubMed1991

[Antihypertensive activity of monoclonal antibody to angiotensin II].

The antihypertensive effect of monoclonal antibody to angiotensin II (MAAII) was studied in renovascular hypertensive (RVH) rats. We found that MAAII could antagonize the pressor effect of exogenous angiotensin II but not of vasopressin in vivo. Five minutes after the administration of MAAII (15 mg/kg, i.v.), plasma angiotensin II could not be detected by radioimmunoassay and the mean blood pressure (MBP) decreased in RVH rats more than in normotensive rats (delta MBP: -5.33 +/- 0.12 and -1.17 +/- 0.29 kPa, respectively, P less than 0.01). The hypotensive effect of captopril was markedly inhibited by prior administration of MAAII, while that of nitroprusside and phentolamine was not. The results suggest that the antihypertensive effect of MAAII is mainly due to its specific binding to circulating angiotensin II.

Angiotensin II↗
PubMed1990

Rat serine dehydratase gene codes for two species of mRNA of which only one is translated into serine dehydratase.

With the previously obtained rat liver serine dehydratase cDNA (SDH2; Ogawa, H., Miller, D.A., Dunn, T., Su, Y., Burcham, J. M., Peraino, C., Fujioka M., Babcock, K., and Pitot, H. C. (1988) Proc. Natl. Acad. Sci. U.S. A. 85, 5809-5813) as a probe, we isolated a different species of cDNA (SDH3) from the same cDNA library from which SDH2 was obtained. Nucleotide sequence analysis has indicated that SDH3 has an open reading frame which encodes 327 amino acid residues and which is identical to that of the cDNA obtained by Noda et al. (Noda, C., Ito, K., Nakamura, T., and Ichihara, A., (1988) FEBS Lett. 234, 331-335). Primer extension analysis and RNase protection mapping clarified that the SDH3 mRNA was the major mRNA for serine dehydratase in the liver, and its transcription begins with a T residue located 23 nucleotides down-stream of a TATA-like box. In vitro transcription/translation experiment demonstrated that SDH3 encoded a polypeptide of 35 kDa, a size in agreement with that of the subunit of the purified protein, whereas SDH2, despite having a size larger than SDH3, produced a peptide of much smaller size that reacted with anti-serine dehydratase IgG. SDH2 was found to have a stop codon early in the sequence and is predicted to encode a polypeptide of 8.9 kDa. Also, SDH2 has a 5'-noncoding sequence different from that of SDH3. These results indicate that alternative transcription initiation and different modes of splicing of the primary transcripts of rat serine dehydratase gene result in the formation of two species of mRNA, of which only one is translated into the mature serine dehydratase protein.

Amino Acid Sequence↗
PubMed1990

Regulation of the expression of the serine dehydratase gene in the kidney and liver of the rat.

Serine dehydratase was induced in the kidneys of normal rats by the administration of either glucagon or dexamethasone. The increase in enzyme activity was associated with an increase in both enzyme protein and its mRNA, which were determined respectively by Western blot and RNA blot analysis. No apparent differences were observed between kidney and liver in the molecular weights of serine dehydratase proteins and the sizes of their mRNAs. Although kidney serine dehydratase was dramatically induced by either glucagon or dexamethasone, the liver enzyme was induced by glucagon but not by dexamethasone alone in the intact rat. On the other hand, liver serine dehydratase was induced in starvation, diabetes mellitus, and a high-protein diet. The kidney enzyme could not be induced under any of these conditions.

Animals↗
PubMed1990

Numerical technique and computational procedure for isotachophoresis.

This paper presents a new numerical method for computation of solutions of prototypical equations of isotachophoresis. Numerical computation is complicated because the Poisson equation, which relates electrostatic potential to space charge density, contains a small parameter. This parameter is usually assumed to have the value of zero. Under this assumption the Poisson differential equation is replaced by an algebraic equation, which is often called the equation of electroneutrality, because it indeed states that the electrolyte is electrically neutral this assumption were not studied in the past. Here we propose an iterative procedure which allows for computation of solutions without the assumption of electroneutrality. The accuracy is controlled by a number of iterations and is limited by a computer round-off error only. The method is based on our previously published theory of existence and uniqueness of solutions of isotachophoretic equations. Details of the computational algorithm for prototypical equations of isotachophoresis are given. A numerical example and comparison with previously published data are also provided.

Algorithms↗
PubMed1988

Isolation and nucleotide sequence of the cDNA for rat liver serine dehydratase mRNA and structures of the 5' and 3' flanking regions of the serine dehydratase gene.

Rat serine dehydratase cDNA clones were isolated from a lambda gt11 cDNA library on the basis of their reactivity with monospecific immunoglobulin to the purified enzyme. Using the cDNA insert from a clone that encoded the serine dehydratase subunit as a probe, additional clones were isolated from the same library by plaque hybridization. Nucleotide sequence analysis of the largest clone obtained showed that it has 1444 base pairs with an open reading frame consisting of 1089 base pairs. The deduced amino acid sequence contained sequences of several portions of the serine dehydratase protein, as determined by Edman degradation. Rat liver serine dehydratase mRNA virtually disappeared from livers of rats fed a protein-free diet for 5 days. Several genomic clones were isolated from two libraries. Determinations of the transcription start site and the structure of the 3' flanking region of the gene indicated that the coded mRNA is 1504 nucleotides long. The 5' promoter region contained a variety of sequences similar to several consensus sequences believed to be important for the regulation of specific gene expression.

Amino Acid Sequence↗
PubMed1987

First report of an epidemic of diarrhoea in human neonates involving the new rotavirus and biological characteristics of the epidemic virus strain (KMB/R85).

An outbreak of diarrhoea in neonates occurred at the nurseries of the Department of Obstetrics of Zhao Tong Regional Hospital, Yunnan Province, from the middle of August to the end of November, 1985. Fifty-one percent of children were affected 2-8 days after birth. The clinical symptoms were mild; patients mainly had diarrhoea and did not vomit. Rotaviruses were detected in 66.7% by RNA PAGE and in 72.7% by EM. The virus strain designated as KMB/R85 had a typical morphology, which was indistinguishable from that of infantile rotaviruses by EM. The viral RNA genome was composed of 11 segments. The buoyant density in CsCl was 1.377 g/cm3. The KMB/R85 strain possessed a hemagglutinin for rhesus monkey erythrocytes. By ELISA, IEM, and HAI, it was found that KMB/R85 strain did not possess the common group antigen shared by group A rotaviruses and was antigenically similar to the Chinese adult diarrhoea rotavirus (serogroup B).

Centrifugation, Isopycnic↗
PubMed1987

[G-banded chromosome analysis of bone marrow and peripheral blood cells from small cell lung cancer (SCLC) patients].

Detailed G-banded chromosome analysis was carried out on the bone marrow and/or PHA-stimulated peripheral blood cells from 17 SCLC patients (14 males and 3 females), who were diagnosed cytologically or pathologically or both. Twelve of them had no prior treatment and 16 had a heavy smoking history. High chromosome aberration rates were found in the bone marrow (31% for average structural aberration rate and 63% for numerical aberration rate) and peripheral blood cells (37% for average structural aberration rate and 49% for numerical aberration rate). The smoking index, as a whole, was positively correlated to the structural chromosome aberration rate, indicating that smoking is one of the most important environmental factors in causing chromosome aberrations. But some patients gave a high aberration rate dis-proportional to their smoking index, suggesting that genetically determined susceptibility to smoking or even other factors also play an important role. The structural chromosome aberrations in the bone marrow and peripheral blood cells were mainly clustered on chromosome 3 and chromosomes 1, 9 and 11, respectively. The aberration types were manifold and complicated. No consistent or specific aberration as del 3p14-23 for SCLC was found in this study.

Bone Marrow↗
PubMed1987

[Hemihepatectomy under hepato-portal interruption at normal temperature for liver malignancies--a report of 20 patients].

From July 1984 to December 1985, hemihepatectomy was done in 20 liver cancer patients under normothermic interruption of porta hepatis. There were 19 primary and 1 secondary liver carcinomas. Of the former, 17 (89%) were associated with mild or moderate cirrhosis. The peak age ranged 36-60 years. Right hemihepatectomy was performed in 18 and left hemihepatectomy in 2 with an operative mortality of 0%. Hepatic failure or secondary bleeding was not found. In the specimens resected, the largest weight was 2,500 gm. The normothermic interruption of porta hepatis usually lasted 15-25 minutes, a time long enough for hemihepatectomy. This procedure, being simple in manipulation and less detrimental to physiologic and biochemical balance in the human body, is relatively practical and beneficial to hepatectomy.

Adult↗