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Biomedical subjects

S C Yu

Publications and source records attributed to S C Yu.

At least 91 records · Page 5Linked to original sources
PubMed1990

Absence of growth-hormone receptor in hepatocellular carcinoma and cirrhotic liver.

Hepatocellular carcinoma is a hormone-sensitive tumor. It has been reported that thyroxine and prolactin significantly stimulated hepatoma growth, whereas growth hormone failed to do so. To learn whether the growth hormone receptor is present in human hepatocellular carcinoma, we used radioreceptor assays in samples of human hepatocellular carcinoma. The liver tissues adjacent to hepatocellular carcinoma (mostly cirrhotic) and control liver tissues (taken during various surgical procedures) were also studied. The study results showed that the affinity constant and capacity of high-affinity growth hormone receptor in normal liver tissues were 6.6 +/- 2.0 x 10(10) mol/L-1 (mean +/- SE, n = 7) and 20.7 +/- 11.5 fmol/mg protein, respectively. The affinity constant and capacity of low-affinity growth hormone receptor in normal liver tissues were 8.9 +/- 3.3 x 10(9) mol/L-1 and 64.7 +/- 32.1 fmol/mg protein, respectively. The absence of growth hormone receptor in human hepatocellular carcinoma and cirrhotic liver samples may explain the absence of growth hormone in the stimulation of hepatoma growth and the decrease of somatomedin levels in cirrhosis.

Adult↗
PubMed1990

Continuous blood glucose monitoring with feedback-controlled glucose infusion during surgical management of insulinoma: report of a case.

Perioperative management of insulinoma may be facilitated by the use of a glucose-controlled insulin infusion system (GCIIS; Biostator System, Miles Laboratories Inc., Elkhart, Ind.). We monitored the blood glucose levels and glucose infusion rates before, during and after surgery in a 35-year-old woman with insulinoma. After an overnight fast, glucose was infused according to a preset program and maintained the blood glucose level at around 50 mg/dl. Depression of the blood glucose level and simultaneous elevation of the glucose infusion rate were noted when the tumor was massaged. A sharp decrease in the glucose infusion rate occurred almost immediately after removal of the tumor. It took about 4 minutes for the blood glucose to go up to a level of 90 mg/dl. These results demonstrate the usefulness of GCIIS not only in maintaining stationary blood glucose, but also in localizing the tumor and in providing evidence of complete removal of the tumor. When the infusion system is programmed appropriately, the glucose infusion rate, as compared to the blood glucose level, reacts more quickly and sensitively to sudden changes in insulin levels.

Adult↗
PubMed1988

Detergent treatment of Dictyostelium discoideum cells allows examination of internal cell type-specific antigens by flow cytometry.

Monoclonal antibodies are used extensively in flow cytometry to identify subpopulations of cells differing in surface antigens. Conventional studies on living cells do not allow analysis of internal antigens, because antibody molecules do not pass through an intact plasma membrane. It is important for developmental studies on Dictyostelium discoideum that not only surface but also internal antigens be analysed. Here techniques are reported that make possible such studies by permeabilising cells with mild detergent treatments using digitonin. Flow cytometer profiles of unfixed cells show that antigens recognised by two monoclonal antibodies, MUD102 and MUD3, are found inside subpopulations of cells in the D. discoideum slug. Double-labelling experiments were carried out to demonstrate that the antigens recognised by these antibodies are present inside prespore but not prestalk cells. The detergent treatment leads to loss of forward-angle light scatter, but 90 degrees light scatter of cells is not greatly affected. While fixed cells sometimes gave satisfactory results, internal labelling did not reliably demonstrate the two subpopulations observed with unfixed cells.

Animals↗
PubMed1988

Status of hepatitis B virus DNA in hepatocellular carcinoma: a study based on paired tumor and nontumor liver tissues.

To investigate the hepatitis B virus (HBV) DNA status in the liver when hepatocellular carcinoma (HCC) has developed, 35 paired nontumorous and tumorous liver tissues from 27 hepatitis B surface antigen (HBsAg)-seropositive and 8 HBsAg-negative patients with HCC were studied by Southern blot analysis. The hybridization patterns of HBV DNA were different in the nontumor and tumor parts in 26 (96.3%) of the 27 HBsAg-positive patients. In the nontumor parts, integration of HBV DNA into the host genome was significantly less when compared to the tumor parts (15/27 vs. 25/27, P less than 0.05), whereas free replicative viral forms were significantly more frequent (17/27 vs. 7/27). The integrated HBV DNA in the nontumor parts showed discrete band patterns in the majority of cases (13/15). Hepatitis B e antigen (HBeAg) was significantly associated with the expression of free replicative forms of HBV DNA in the tumor tissues. An integrated HBV DNA sequence was detected in the tumor part of one HBsAg-negative patient, but not in her nontumor counterpart. Our observation that discrete integrated HBV DNAs are present in the nontumor part, representing subclinical clonal expansion that precedes the development of HCC, suggests the risk of future new tumor growth from these cell clones.

Carcinoma, Hepatocellular↗
PubMed1988

Carcinoma of the gallbladder from an anomalous connection between the bile duct and the pancreatic duct.

Anomalous connection between the common bile duct and the pancreatic duct has recently been reported to be associated with cancerous changes of the biliary tract. A 52-year-old Chinese man had a fungating tumor in the gallbladder, and a long common channel between the bile duct and the pancreatic duct. The association of these two rare disease entities especially in a Chinese man may imply a close relationship between pancreatobiliary anomalous connection and the gallbladder cancer. It is thus prudent to monitor patients with such an anomalous connection closely by serial ultrasonic examination. More aggressively, prophylactic cholecystectomy and reconstruction of the biliary tract may be indicated.

Adenocarcinoma↗
PubMed1985

Interaction of histones with estrogens. Covalent adduct formation with 16 alpha-hydroxyestrone.

Disturbed estrogen metabolism leading to increased 16 alpha-hydroxyestrone (16 alpha-OHE) has been described in patients with systemic lupus erythematosus and mammary carcinoma. Previous studies showed the formation of covalent complexes between 16 alpha-OHE and nonspecific cellular membrane proteins. The present study is concerned with the interaction of 16 alpha-OHE and histones. Covalent adduct formation between 16 alpha-OHE and individual histones was maximal with H1 histone. Other endogenous estrogens such as estrone, estradiol, and estriol did not interact with histones and form covalent adducts, nor did they interfere with the interaction of 16 alpha-OHE with these nuclear proteins. The evidence supports that the adduct formation between 16 alpha-OHE and histones proceeds via a stabilized Schiff base and subsequent rearrangement. This adduct formation which may have in vivo analogues may represent a mechanism for cellular transformation by this estrogen metabolite.

Estradiol↗
PubMed1977

The dependence of the lipid bilayer membrane: buffer partition coefficient of pentobarbitone on pH and lipid composition.

1 The membrane/buffer partition coefficient of [14C]-pentobarbitone has been determined as a function of the lipid composition of bilayer membranes. 2 A new technique based on ultrafiltration gave comparable results to conventional techniques but required less time for equilbration. 3 The membrane/buffer coefficient was independent of pentobarbitone concentration in the range studies. 4 The apparent partition coefficient varied with pH and was a linear function of the degree of dissociation of pentobarbition. 5 Both the charged and uncharged forms of pentobarbitone partitioned into the membrane, the latter to a much greater extent than the former. 6 At low pH the highest partition coefficient observed was in egg phosphatidylcholine bilayer membranes. 7 Incorporation of cholesterol or phosphatidic acid into phosphatidylcholine membranes greatly reduced the partition coefficient. 8 High pressures do not greatly change these partition coefficients.

Buffers↗