Search PubMed⌕ Search

Biomedical subjects

T T Wang

Publications and source records attributed to T T Wang.

At least 55 records · Page 3Linked to original sources
PubMed1994

Isoproterenol and 8-bromo-cyclic adenosine monophosphate stimulate the expression of the angiotensinogen gene in opossum kidney cells.

To investigate whether the expression of the renal angiotensinogen (ANG) gene is regulated by beta-adrenoceptors and the cAMP-dependent protein kinase A pathway, we introduced stably the fusion gene containing the 5'-flanking regulatory sequence of the ANG gene with a human growth hormone (hGH) gene as a reporter, pOGH (ANG N-1498/+18), into opossum kidney (OK) cells. We successfully obtained several stable transformants with a high expression of the pOGH (ANG N-1498/+18) fusion gene. One stable transformant (OK 27) that is able to maintain the expression of pOGH (ANG N-1498/+18) in culture for more than a year was used in the present study. The level of expression of the pOGH (ANG N-1498/+18) in OK 27 was evaluated by the amount of immunoreactive-hGH (IR-hGH) secreted into the culture medium. The addition of isoproterenol (10(-11) M to 10(-9) M) stimulated the expression of pOGH (ANG N-1498/+18) and increased the accumulation of intracellular cAMP. Higher concentrations of isoproterenol (that is, greater than 10(-9) M) had low or minimal effect. In contrast, the addition of 8-bromo-cAMP (8-Br-cAMP) and forskolin stimulated the expression of pOGH (ANG N-1498/+18) in a dose-dependent manner. The stimulatory effect of isoproterenol was blocked by the presence of propranolol, atenolol and ICI 118,551. The addition of ICI 118,551, however, was less effective than atenolol. Furthermore, the stimulatory effect of isoproterenol and 8-Br-cAMP on the expression of the pOGH (ANG N-1498/+18) was inhibited by the presence of Rp-cAMP (an inhibitor of cAMP-dependent protein kinase A I and II).(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1994

[Lipid metabolism and pregnancy induced hypertension].

Lipid metabolism was studied in 30 healthy non-pregnant women, 35 normal pregnant women and 34 patients with pregnancy induced hypertension (PIH). Total cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), LDL-C/HDL-C ratio, and athero-sclerosis index (AI) were determined. In comparison with the non-pregnant status, lipid levels did not increased during normal mid-trimester pregnancy, but significantly increased at late trimester of normal pregnancy (P < 0.05). There was no significant difference in lipid levels between normal late pregnancy and PIH of mild and moderate degree, but TG and AI were significantly higher in cases with severe PIH. It showed that: lipid profiles in severe PIH was characterized by type IV hyperlipidemia; high lipid levels during normal late pregnancy might be a physiological phenomenon which presents a risk factor for PIH; marked increase of TG and AI in severe PIH may result in a rise of lipid peroxide (LPO).

Adult↗
PubMed1994

[Complication of ascites in pregnancy-induced hypertension].

Twenty three pregnancy-induced hypertension (PIH) patients with ascites were treated in Beijing Obstetrics and Gynecology Hospital from Jan. 1981 to April 1992. The incidence of ascites in PIH was 1.9/1000 in total in this study, and 21.6/1000 in severe PIH. Clinical manifestations showed an early onset of PIH at 29.4 +/- 4.8 weeks, and ascites occurred at 32.4 +/- 7.4 weeks. There were 18 cases out of 23 who had no routine antenatal care, all of them had complications with IUGR. Laboratory studies: ascites showed transudate in all of them except one with chronic nephritis exhibiting milky appearance. 10% of patients had abnormal complete blood count (CBC) and 13%-17% abnormal electrolytes. 17.0% of the patients had GPT > 30IU, 21.0% urea nitrogen > 35 g/L, 95.7% had plasma albumin < 35 g/L. The ratio of A/G was < 1.5 in all patients. We conclude that once PIH was 1.5 in all patients. We conclude that once PIH was complicated by ascites, it can not be cured by active treatment. It is an indication for termination of pregnancy. After delivery the ascites and pleural effusion gradually disappeared in 2 weeks. Perinatal mortality rate was as high as 42.1% because of premature induced labor and IUGR.

Adult↗
PubMed1993

Production of human plasma retinol-binding protein in Escherichia coli.

We designed a polymerase chain reaction (PCR) primer pair which allowed us to clone the cDNA coding for the human plasma retinol-binding protein (hRBP) into an Escherichia coli expression vector. Production of hRBP was confirmed by probing Western blots with antisera against plasma hRBP. Purification and characterization of the E. coli-produced plasma hRBP are also described. The availability of this expression system makes it possible to obtain large quantities of hRBP to facilitate our continuing studies of retinol and RBP metabolism.

Amino Acid Sequence↗
PubMed1993

Cloning and expression of the full-length cDNAS encoding human liver class 1 and class 2 aldehyde dehydrogenase.

The amino acid sequences of both human class 1 and 2 aldehyde dehydrogenase (ALDH) and the sequences of the genes coding for them are known. Based on this sequence data, we designed primers and isolated the full-length cDNAs encoding both isozymes from a human liver mRNA pool. cDNAs were subcloned in the plasmid pT7-7 and expressed in Escherichia coli with a yield of approximately 3 mg ALDH protein/liter of cell culture, although only one-third of the enzyme was soluble. The soluble recombinantly expressed ALDHs were purified to homogeneity using a hydroxyacetophenone-Sepharose affinity column. The mitochondrial isozyme had a subunit molecular weight of 55 kDa, an isoelectric point of 4.9, and a specific activity of 1.10 units/mg, which were in good agreement with that from the native enzyme. The expressed cytosolic isozyme had the same subunit molecular weight (55 kDa) and pI (5.4) as that reported for the native enzyme and had a specific activity of 0.26 units/mg. The expressed mitochondrial isozyme could be recognized by antibodies raised against rat mitochondrial ALDH, whereas the cytosolic isozyme could be recognized by antibody raised against horse cytosolic ALDH.

Aldehyde Dehydrogenase↗
PubMed1991

The nucleotide sequence of Schwanniomyces occidentalis alpha-amylase gene.

The nucleotide sequence of the coding and regulatory regions of the alpha-amylase-encoding gene (AMY) of Schwanniomyces occidentalis has been determined. This sequence contained an open reading frame of 512 codons, from which a protein with Mr of 53,723 could be predicted. A putative signal sequence encoding for 25 amino acids was proposed for the 5' end of the open reading frame. Regulatory sequences, such as TATA box, CCAAT box and a signal sequence for polyadenylation and transcription termination could be found in the flanking regions of AMY gene. The deduced amino acid sequence also contained four common conserved regions characteristic of other alpha-amylase proteins.

Amino Acid Sequence↗
PubMed1991

Cell-cell interactions trigger the rapid induction of a specific high mobility group-like protein during early stages of conjugation in Tetrahymena.

Conjugation in Tetrahymena represents an ordered developmental pathway which represents the sexual phase of the ciliate life cycle. This pathway is initiated when starved cells of opposite mating types are mixed and are allowed to make a series of cell-cell contacts (a period termed costimulation) which lead to the formation of mating pairs. Here, we demonstrate that two previously described abundant high mobility group (HMG)-like proteins, HMG B and HMG C, whose synthesis appeared to be coordinately regulated in vegetative cells, are not required during the same stages of conjugation. The level of mRNA for both HMG B and HMG C is high during vegetative growth and during the development of new macronuclei. However, specific induction of HMG B mRNA is observed soon after cells of opposite mating types are mixed. Thus, the genes which encode HMG B and HMG C in Tetrahymena can be controlled independently or coordinately. Nuclear run-on experiments show that a significant factor underlying the rapid induction of HMG B message early in the sexual cycle is an increase in the transcriptional activity of the HMG B gene. Experiments are presented which show that this induction of HMG B message requires protein synthesis and is dependent upon the cell-cell contacts made during costimulation. Essentially all of the HMG B protein, which is newly synthesized during this period, is targeted to parental macronuclei where it serves an as yet undetermined function(s).

Animals↗
PubMed1991

Effects of protein size on the rate of import of the precursors of aldehyde dehydrogenase and ornithine transcarbamylase into rat liver mitochondria.

It is known that a signal peptide is required for the import of a protein into mitochondrial matrix. It is also known that a signal peptide can be attached to any protein and allow it to be imported. We recently reported that the rate of import of rat liver mitochondrial aldehyde dehydrogenase precursor was slower than that of ornithine transcarbamylase precursor (Wang TTY, Farrés J, and Weiner H. Arch Biochem Biophys 272, 440-449, 1989). It was not known if the difference in the rate of import was related to the fact that the mature portion of aldehyde dehydrogenase is larger (500 amino acids compared with 322 amino acids) or because the signal peptides were different. We further showed that treatment of the mitochondria with alcohols caused an inhibition of the import of the precursor of aldehyde dehydrogenase but not that of ornithine transcarbamylase. In the present study we constructed chimeric proteins that contained the signal peptide from one precursor protein and the mature portion from the other. We found that the rate of import was related to the overall size of the precursor protein. Consistent with this observation was finding that a truncated aldehyde dehydrogenase precursor, which contained 317 amino acids, was imported more rapidly than was the authentic precursor. Consistent with this finding was the fact that butanol caused the inhibition of only the large precursor proteins. Thus, it appears that size of the protein being imported is a major determinant of the rate at which a precursor protein is imported into mitochondria.

Aldehyde Dehydrogenase↗
PubMed1991

Molecular biological studies on liver mitochondrial aldehyde dehydrogenase.

The tools of molecular biology were applied to study different facets of liver aldehyde dehydrogenase. One point investigated was the sequence of the various liver forms of the enzyme and the structure of the genes coding for the enzyme. It was found that an intron existed between the gene sequence coding for amino acids 21 and 22. The presence of the intron could explain why no sequence identity exists between the first 21 residues of the cytosol and mitochondrial isozymes while there is 70% identity between the remaining amino acids. Having the cDNA coding for the mitochondrial enzyme allowed us to produce the precursor form of the enzyme in rabbit reticulocytes and perform in vitro import into isolated mitochondria where it was found that alcohols caused an inhibition of import. The active enzyme was expressed in E. coli and site directed mutagenesis was performed to probe for the active site residues. The role of cysteine and position 302 and glutamate at position 487 was studied.

Alcohols↗
PubMed1990

Effects of alcohol on the import of aldehyde dehydrogenase precursor into rat liver mitochondria.

We previously showed that incubation of rat liver mitochondria with alcohols resulted in the inhibition of the import of aldehyde dehydrogenase precursor but not that of ornithine transcarbamylase precursor (Wang TTY, Farrés J, and Weiner H: Arch Biochem Biophys 272:440-449, 1989). The time required for inhibition of import to occur was now measured with ethanol (200 mM) and butanol (100 mM) at 0 degree and 30 degrees C. It required approximately 30 min to achieve 50% inhibition with butanol and 50 min with ethanol. To further substantiate the membrane perturbing effects of alcohols, we also examined the effect of oleic acid on import. We found that incubation of mitochondria with oleic acid (0-100 microM) resulted in inhibition of aldehyde dehydrogenase precursor import in a dose response fashion. In addition to in vitro effects of alcohols on import, we conducted a preliminary study on import of protein into liver mitochondria isolated from rats fed ethanol. We found that the rate of aldehyde dehydrogenase precursor import into liver mitochondria isolated from ethanol fed rats was identical to that from control. The results are consistent with finding that the activity and amount of aldehyde dehydrogenase was the same in mitochondria isolated from the alcohol-fed or control animals.

Alcoholism↗
PubMed1989

Liver mitochondrial aldehyde dehydrogenase: in vitro expression, in vitro import, and effect of alcohols on import.

An in vitro expression plasmid (pGRAP) that contained the cDNA coding for the rat mitochondrial aldehyde dehydrogenase precursor was constructed, mRNA was synthesized then translated, and the in vitro synthesized precursor of aldehyde dehydrogenase was used in an in vitro import assay. As expected the 19 amino acid signal peptide of the precursor allowed import of the precursor into rat liver mitochondria. This in vitro system was used to examine the effect of alcohols on import. It was found that the alcohols (ethyl, butyl, hexyl, and octyl) tested inhibited the import of the aldehyde dehydrogenase precursor. Pretreatment of the mitochondria with alcohol was responsible for the inhibition. The inhibition appeared to be relatively specific for pre-aldehyde dehydrogenase as the precursor of ornithine transcarbamylase was still imported in the presence of alcohols. Of potential physiological significance was finding that ethanol inhibited import in a dose-response fashion; 50% inhibition occurred at 75 mM, a concentration achievable during the ingestion of alcohol. In addition, the concentrations of alcohols required to produce an inhibitory effect on import decreased as the hydrocarbon chain length of alcohols increased. The inhibitory effect of alcohols appeared to be specific as other solvents examined did not inhibit import. We postulate that alcohols may perturb the mitochondrial membrane and affect the receptor-translocator necessary for the import of the aldehyde dehydrogenase precursor.

Aldehyde Dehydrogenase↗
PubMed1989

Uterine malignancy developing after long term use of IUCD additional report of 2 cases: endometrial stromal sarcoma and leiomyosarcoma.

In our 2 previous papers published in this Journal, we had 5 cases of uterine malignancies developing after long term use of IUCD's. In the present paper 2 cases of such association are to be added. One case ATH with right adnexectomy was performed for persisting vaginal bleeding after 22 years of Lippes Loop application and recurrence 8 years after the first operation. Pathological diagnosis is endometrial stromal sarcoma. The other case is a leiomyosarcoma developing after 25 years of Lippes Loop application. Although no cause and effect relationship between IUCD use and uterine malignancy in human beings has been proved, the increase in such cases suggests to us that long term application should be avoided, particularly in view of the positive animal experiments. The successive detection of such cases in a relatively short period of time prompts us to make further studies to gain a deeper insight into such associations.

Female↗
PubMed1989

Cloning and Expression of a Schwanniomyces occidentalis alpha-Amylase Gene in Saccharomyces cerevisiae.

An alpha-amylase gene (AMY) was cloned from Schwanniomyces occidentalis CCRC 21164 into Saccharomyces cerevisiae AH22 by inserting Sau3AI-generated DNA fragments into the BamHI site of YEp16. The 5-kilobase insert was shown to direct the synthesis of alpha-amylase. After subclones containing various lengths of restricted fragments were screened, a 3.4-kilobase fragment of the donor strain DNA was found to be sufficient for alpha-amylase synthesis. The concentration of alpha-amylase in culture broth produced by the S. cerevisiae transformants was about 1.5 times higher than that of the gene donor strain. The secreted alpha-amylase was shown to be indistinguishable from that of Schwanniomyces occidentalis on the basis of molecular weight and enzyme properties.

Journal Article↗