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Biomedical subjects

S H Yap

Publications and source records attributed to S H Yap.

At least 145 records · Page 8Linked to original sources
PubMed1982

Distribution of mRNAS of fibrinogen polypeptides and albumin in free and membrane-bound polyribosomes and induction of alpha-fetoprotein mRNA synthesis during liver regeneration after partial hepatectomy.

To study the effect of regenerative response of the liver following partial hepatectomy on the synthesis of major plasma proteins (secretory proteins), we have determined the sequence contents and the distribution of albumin and fibrinogen polypeptide mRNAs in rat liver at intervals after partial hepatectomy and sham operation. Using a quantitative technique for the isolation of polyribosomes, we demonstrated that the distribution of RNA between free and membrane-bound polyribosomal fraction was unchanged in these experiments. There was no shift in the polyribosomal population to favor free polyribosomes after partial hepatectomy. However, there was a dramatic increase (5-6-fold) of the fibrinogen polypeptide mRNA concentration during the first 24 h after resection. In contrast, the albumin mRNA concentration decreased (2-3-fold). There were no alpha-fetoprotein mRNA sequences detectable in any liver RNA fraction in these experimental animals. In sham-operated rats with intact livers, similar changes of fibrinogen polypeptide and albumin mRNA concentrations as described in regenerating liver after partial hepatectomy, were observed. These results suggest that albumin and fibrinogen synthesis after partial hepatectomy is reciprocally regulated at the mRNA level and represents a nonspecific acute phase response to surgical trauma.

Albumins↗
PubMed1982

Sequence content of alpha-fetoprotein, albumin and fibrinogen polypeptide mRNAs in different organs, developing tissues and in liver during carcinogenesis in rats.

To investigate the variable gene activities of alpha-fetoprotein, albumin and fibrinogen polypeptides as markers of 'liver specific proteins' in different developing organs or tissues, we have used specific complementary DNA probes to detect and to quantitate alpha-fetoprotein, albumin and fibrinogen polypeptide mRNA, respectively, in RNA fractions, prepared from various tissues of rats at different stages of fetal and postnatal development and from hepatomas induced by diethylnitrosamine. The results indicate that there is no consistent relationship between sequence content of alpha-fetoprotein, albumin and fibrinogen polypeptide mRNA in different developing tissues. Intestines which are like the liver also of endodermal origin do not contain alpha-fetoprotein, albumin and fibrinogen polypeptide mRNAs, while kidneys which are mesodermal in origin were found to be alpha-fetoprotein, albumin and fibrinogen polypeptide mRNA producers in neonatal life. In yolk sac, only alpha-fetoprotein and fibrinogen polypeptide mRNA could be detected. In the liver, the increased level of albumin and fibrinogen polypeptide mRNA during fetal and neonatal development is accompanied with a diminished amount of alpha-fetoprotein mRNA. The neosynthesis of alpha-fetoprotein mRNA in the liver during carcinogenesis occurred without a decreased content of albumin and fibrinogen polypeptide mRNAs. These findings suggest that complex mechanisms of gene regulation are involved in variable gene activities of alpha-fetoprotein, albumin and fibrinogen polypeptides in cells of different organs or tissues developed from a single cell.

Aging↗
PubMed1982

Neodynium YAG laser photocoagulation in experimental gastric lesions in pigs.

Gastric lesions produced in pigs were used as a model to assess the efficiency and safety of Neodynium YAG laser in photocoagulation of bleeding upper gastrointestinal lesions. Bleeding gastric lesions were induced in heparinized animals and photocoagulated by a series of pulses of varying duration. Depth of necrosis in the intact gastric wall was examined as a function of radiation density and exposure time. Histologic examination was performed 1 hour and 3,7 and 21 days after exposure. The results showed that tissue destruction was less with intermittent application of energy than with a continuous radiation. intermittent administration of energy of high density (82 watts) and a short exposure time (1 sec) resulted in efficient photocoagulation, with tissue destruction not deeper than halfway through the muscularis propria. No perforation was observed in these experiments.

Animals↗
PubMed1981

Acute effects of ethanol intake on albumin and total protein synthesis in free and membrane-bound polyribosomes of rat liver.

Controversial results have been reported in the last few years concerning the effects of ethanol on hepatic protein synthesis. In most of the studies no distinction has been made between the synthetic capabilities of the polyribosomes and the secretory product of labelled protein by the hepatocytes. In order to assess the influence of a single feeding of ethanol on the synthesis of albumin and total protein by the polyribosomes of rat liver, free and membrane-bound polyribosomes were isolated quantitatively from rats given 4--8 g ethanol per kg body weight 3--5 h before killing. The following results were obtained: (1) No difference was found in yield and size of free and membrane-bound polyribosomes isolated from control and ethanol-treated rats. The abilities to synthesize albumin and total protein were also equal for polyribosomes from both groups. (2) Addition of 1% ethanol to the incubation mixture of protein synthesis lowered albumin and total protein synthesis by 20%. No effect was observed with 0.5% ethanol. (3) Cell sap prepared from ethanol-treated rats contains a factor or factors which stimulate protein synthesis (10--15%). (4) The albumin mRNA sequence content was not changed in free and membrane-bound polyribosomal RNA fractions of ethanol-treated rats as compared to the control animals.

Animals↗
PubMed1981

Effect of starvation of the synthesis rate of albumin in vivo and its relation to the concentrations of amino acids in the peripheral blood, the portal circulation and in the liver cytosolic fraction.

The synthesis rate of albumin was measured in vivo by the 14C-carbonate method in fed control rabbits, in animals after a short-term fast (24-36h), and after starvation for 8 days. The albumin synthesis rate was significantly lower in animals after a short-term fast in comparison to the fed control group. A starvation for a longer period did not further decrease the synthesis rate of albumin. The serum concentrations of essential amino acids from the systemic circulation and from the portal blood after a short-term fast did not differ significantly nor were they higher in comparison to those of fed rabbits. Despite the increased serum levels of the most essential amino acids in the systemic venous blood after long-term starvation, there were no or little changes in concentrations of amino acids in portal blood and liver cytosolic fraction from fasted animals as compared to those of the fed group. These findings suggest that the reduction of albumin synthesis in fasting state is not primarily due to a reduction in the direct availability of these amino acids for albumin synthesis in the liver.

Albumins↗
PubMed1979

Regulation of albumin synthesis in rat liver.

The present report reviews our findings on the subcellular distribution of albumin mRNA in rat liver under normal and abnormal physiologic conditions, the identification of albumin mRNA in specific mRNP complexes in liver cytosol of starved rats, and evidence fo albumin mRNA sequences in a higher molecular weight nuclear precursor to cytoplasmic albumin mRNA.

Albumins↗
PubMed1979

[Percutaneous transhepatic cholangiography with the Okuda or Chiba needle (author's transl)].

Introduction of the thin flexible needle (Chiba or Okuda needle) has revived percutaneous transhepatic cholangiography, even though there are more recent methods of investigating the biliary tract. Personal results in 65 patients demonstrate that the needle can be successfully introduced in all instances, as long as the biliary tracts are dilated, the success rate being 68% if they are not. The complication rate was 9.2%, but there was no death.

Adolescent↗