Biomedical subjects
S Liu
Publications and source records attributed to S Liu.
[An evaluation of nonsurgical treatment for severe acute pancreatitis].
In this prospective study, the rationality of non-operative treatment for severe acute pancreatitis was evaluated. Twenty-four patients aged 15-74 years with a mean age of 46.1 +/- 15.5 years were divided randomly into two groups: 12 patients in nonoperative group and 12 in operative group. The patients treated nonoperatively survived, while 5 patients died of operation. It is suggested that patients with severe acute pancreatitis can be cured by nonoperative management.
[Analysis of beta-thalassemia mutations and prenated diagnosis in Chengdu population].
Ninety-five of non-differential diagnostic patients were detected by dot-blot analysis on enzymatically amplified DNA with a number of allele specific oligonucleotide probes complementary to the most common mutations in Chengdu population. Prenatal diagnosis was accomplished by the same procedure on enzymatically amplified amniocyte DNA. The result revealed fifty-eight cases of beta-thalassemia. Of the 73 chromosomes tested, twenty-eight (38.4%) had the codon 17(A-->T) mutation, twenty-one (28.8%) had the codon 41-42(-TTCT) mutation, fourteen (19.0%) had the IVS-I-654(C-->T) mutation; nt--28(A-->G) and nt--29(A-->G) mutations were six (8.2%) and four (5.5%) respectively.
[The effect of topically garlic solution painting on experimental oral precancer and oral cancer in rats].
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[Study of DNA content, immunophenotype in childhood non-Hodgkin's lymphomas].
The DNA content, immunophenotypes and Ag-NOR of 63 cases of childhood NHL have been studied with flow cytometry and immunohistochemistry. The results showed that the incidence of aneuploidy, the numbers of Ag-NOR and PI increased significantly with increasing histological grade. The numbers of PI were also a valuable prognostic parameter. There was a positive correlation between the numbers of PI and AgNOR. No significant correlation was seen between the survival rates of diploid and aneuploid tumors. The highest to lowest survival rates being in the sequence of unclassified tumors, T-cell tumors and B-cell tumors.
[The ultrastructure of intermediate type trophoblast cell].
Transmission electron microscopy was used to clarify the detailed morphology of the "intermediate type" trophoblast cell in normal and tumor issue. 67 normal placental villi specimen, 10 placental bed specimens and 10 malignant mole, 10 hydatidiform mole, 5 choriocarcinoma specimen (the last three types taken before chemotherapy) were examined. Results showed that the transitional type trophoblasts of the placenta were developed from cytotrophoblasts through differentiation and fusion to syncytiotrophoblasts which showed features of maturation and aging, having features of cytotrophoblast nuclei and syncytiotrophoblast cytoplasm. The transitional trophoblast of placental bed showed similar morphology as that of transitional type cells of villi. The morphology of transitional type cells of villi. The morphology of transitional type cells of trophoblastic tumors had both normal morphology and cellular hyperplasia, atypia and features of tumor ultrastructure. The prominent feature was the high electron density of the granules and polymorphic cysts crowded in villi, demonstrating that the morphology of "intermediate type" trophoblasts in placental and tumor tissue are similar, whereas heterotype cellular morphology is present in varying degrees in tumor tissue.
[Expression of insulin-like growth factor-I gene in normal and diabetic rat eye].
The expression of insulin-like growth factor I (IGF-I) gene was studied in both normal and diabetic rat eyes via in situ hybridization. The results revealed the regional expression of IGF-I gene in the rat eyes. The expression of IGF-I mRNA in the internal nuclear layer and ganglion cell layer is strong, in choroid, retinal pigment epithelium and external nuclear layer is moderate, in sclera is weak in degree and no such mRNA is detected in the cornea. The abundance of IGF-I mRNA in diabetic eye tissues is significantly (P < 0.05 or P < or = 0.01) higher than that in normal eye. These findings suggest that (1) functionally, the eye ball be considered to be an "IGF-I paracrine-autocrine system", and (2) the high expression of IGF-I indicate its initiation of diabetic retinopathy and its promotion of the progression of the lesion.
Construction, expression and characterization of tissue-type plasminogen activator mutants.
Three tissue-type plasminogen activator (t-PA) mutants were constructed by recombinant and site-directed mutagenesis techniques. They are del(296-302) with deletion of PAI-1 binding site, N117Q/N184Q with deglycosylation of K1 and K2 domains, and their combination mutant designated as GGI. Then these three mutants were successfully transiently expressed in COS-7 cells, and GGI was further stably expressed in CHO cells. The biological characterization of the expression products indicated that del(296-302) and GGI possessed the resistance to inhibition by PAI-1. In addition, the specific activity of GGI was increased by about 46%, the plasma half-life was prolonged by about one fold, while its affinity for fibrin was not affected.
[The mRNA expression of CD2, CD4 and CD8 in peripheral blood lymphocytes from the patients with acute lymphoblastic leukemia and non-Hodgkin's lymphoma].
The paper for the first time reports the detection of the levels of CD2, CD4 and CD8 mRNA expression in peripheral blood lymphocytes from 9 cases with T-acute lymphoblastic leukemia (ALL) and 10 cases with T-non-Hodgkin's lymphoma (NHL) by using RNA dot blotting technique. It was found that the levels of CD2 mRNA in the two groups of patients were significantly higher than those in the normals. The ratios of the CD4 to CD8 mRNA were also increased in patients with NHL. The significance of this study was discussed.
Derangements in calcium-dependent membrane currents in senescent human fibroblasts are associated with overexpression of a novel gene sequence.
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Alcohol consumption and breast cancer: estrogen receptor status and histology.
Data from a case-control study conducted in New York State during 1982-1984 were used to evaluate the relation between alcohol consumption and estrogen receptor-positive and estrogen receptor-negative breast cancers and alcohol and various histologic subtypes. The cases were women between 20 and 79 years of age with a diagnosis of primary breast cancer. A total of 794 estrogen receptor-positive and 358 estrogen receptor-negative breast cancer cases were available for study. Controls (n = 1,617) were selected from driver's license files of the New York State Department of Motor Vehicles. Information on estrogen receptor status and histology was obtained from hospital records. The risk of estrogen receptor-positive breast cancer was shown to increase with increasing amounts of alcohol consumption in grams per day (odds ratio (OR) = 1.18 (95% confidence interval (CI) 0.88-1.57) for < 1.5 g/day, 1.28 (95% CI 0.91-1.80) for 1.5-4.9 g/day, 1.28 (95% CI 0.96-1.70) for 5.0-14.9 g/day, and 1.35 (95% CI 0.99-1.85) for > or = 15.0 g/day). There was no relation between alcohol consumption and estrogen receptor-negative tumors (OR = 0.92 (95% CI 0.62-1.36) for < 1.5 g/day, 1.19 (95% CI 0.77-1.83) for 1.5-4.9 g/day, 0.94 (95% CI 0.64-1.35) for 5.0-14.9 g/day, and 1.05 (95% CI 0.70-1.59) for > or = 15.0 g/day). The risk for each of the histologic subtypes studied increased with increasing daily alcohol consumption. These findings suggest that alcohol may only increase a woman's risk of estrogen receptor-positive breast cancers.
Refined 1.8 A resolution crystal structure of the porcine epsilon-trypsin.
Porcine epsilon-trypsin is a three-chain inactivated trypsin from the limited autolysis of porcine beta-trypsin. It is cleaved at positions Lys60-Ser61 and Lys145-Ser146. The crystal structure has been determined by using the molecular replacement method, and refined at 1.8 A resolution. The R-value of final model is 0.184. Comparison with the electron density map of porcine beta-trypsin (PTRY) in complex (BBIT), and with that of native bovine beta-trypsin (HTNA), revealed no obvious changes except at the autolysis positions, and no changes at the active center were observed. The autolysis at positions Lys60-Ser61 and Lys145-Ser146 does not affect the conformation of His-57 in the active center and therefore cannot explain for a loss in porcine epsilon-trypsin activity.
A prospective study of alcohol intake and change in body weight among US adults.
Little is known about the role of alcohol in determining change in body weight. In this paper, the authors examine the relation between alcohol intake and body weight in 7,230 US adults aged 25-74 years who participated in the First National Health and Nutrition Examination Survey (1971-1975) and who were reweighed 10 years later (1982-1984). Both cross-sectional and prospective analyses were adjusted for age, race, height, education, health status, smoking status, diet status, physical activity, and total nonalcoholic caloric intake. At baseline, women who reported at least one drink per day weighed 2.3 kg less than nondrinkers (95% confidence interval (CI) -0.4 to -4.2). Little relation was observed between body weight and alcohol intake cross-sectionally among men. Prospectively, both men and women drinkers tended to gain less weight than did nondrinkers (p = 0.006 for trend in women, p = 0.11 for trend in men). Drinkers also had more stable weight over the 10-year follow-up period. Drinkers were less likely to have major weight gain or loss (gaining or losing > or = 10 kg) than were nondrinkers. Compared with nondrinkers, for those who consumed 1-6.9 drinks per week, women had an odds ratio (OR) = 0.7 (95% CI 0.5 to 0.9) for major weight gain and an OR = 0.7 (95% CI 0.5 to 1.1) for major weight loss, while men had an OR = 1.0 (95% CI 0.6 to 1.6) for major weight gain and an OR = 0.7 (95% CI 0.5 to 1.2) for major weight loss. For those who consumed > or = 2 drinks per day, women had an OR = 0.5 (95% CI 0.3 to 1.0) for major weight gain and an OR = 0.8 (95% CI 0.4 to 1.6) for major weight loss, while men had an OR = 0.9 (95% CI 0.5 to 1.6) for major weight gain and an OR = 1.0 (95% CI 0.6 to 1.7) for major weight loss. These data suggest that alcohol intake does not increase the risk of obesity.
(E)-5',6'-didehydro-6'-deoxy-6'-fluorohomoadenosine: a substrate that measures the hydrolytic activity of S-adenosylhomocysteine hydrolase.
(E)-5',6'-Didehydro-6'-deoxy-6'-fluorohomoadenosine (EDDFHA), which is a poor substrate for the oxidative activity of S-adenosyl-L-homocysteine (AdoHcy) hydrolase and thus a poor mechanism-based inhibitor was shown to be a good substrate for the hydrolytic activity of this enzyme. Incubation of EDDFHA with AdoHcy hydrolase (NAD+ form) produces a large molar excess of hydrolytic products [e.g., fluoride ion, adenine (Ade) derived from chemical degradation of homoadenosine 6'-carboxaldehyde (HACA), and 6'-deoxy-6'-fluoro-5'-hydroxyhomoadenosine (DFHHA)] accompanied by a slow irreversible inactivation of the enzyme. The enzyme inactivation was shown to be time-dependent, biphasic, and concomitant with the reduction of the enzyme-bound NAD+ (E.NAD+) to E-NADH. The reaction of EDDFHA with AdoHcy hydrolase was shown to proceed by three pathways: pathway a, water attack at the 6'-position of EDDFHA and elimination of fluoride ion results in the formation of HACA, which degrades chemically to form Ade; pathway b, water attack at the 5'-position of EDDFHA results in the formation of DFHHA; and pathway c, oxidation of EDDFHA results in formation of the NADH form of the enzyme (inactive) and 3'keto-EDDFHA, which could react with water at either the C5' or C6' positions. The partition ratios among the three pathways were determined to be k3':k6':k5' = 1:29:79 with one lethal event (enzyme inactivation) occurring every 108 nonlethal turnovers.(ABSTRACT TRUNCATED AT 250 WORDS)
Silencing of the VHL tumor-suppressor gene by DNA methylation in renal carcinoma.
Mutational inactivation and allelic loss of the von Hippel-Lindau (VHL) gene appear to be causal events for the majority of spontaneous clear-cell renal carcinomas. We now show that hypermethylation of a normally unmethylated CpG island in the 5' region provides another potentially important mechanism for inactivation of the VHL gene in a significant portion of these cancers. This hypermethylation was found in 5 of 26 (19%) tumors examined. Four of these had lost one copy of VHL while one retained two heavily methylated alleles. Four of the tumors with VHL hypermethylation had no detectable mutations, whereas one had a missense mutation in addition to hypermethylation of the single retained allele. As would be predicted for the consequence of methylation in this 5' CpG island, none of the 5 tumors expressed the VHL gene. In contrast, normal kidney and all tumors examined with inactivating VHL gene mutations but no CpG island methylation had expression. In a renal cell culture line, treatment with 5-aza-2'-deoxycytidine resulted in reexpression of the VHL gene. These findings suggest that aberrant methylation of CpG islands may participate in the tumor-suppressor gene inactivations which initiate or cause progression of common human cancers.
Origin of CCK-like immunoreactive nerve fibers in the neurohypophysis of the rat.
Wheatgerm agglutin (WGA) conjugated horseradish peroxidase (HRP) retrograde tracing technique was combined with immunohistochemistry to study the origin of cholecystokinin (CCK)-like immunoreactive (ir) nerve fibers in the neurohypophysis of the rat. The CCK-ir neurons projecting to the neurohypophysis were localized mainly in the magnocellular paraventricular nuclei (mPVN), periventricular PVN, medial parvocelullar PVN, medial preoptic area and dorsal accessory nuclei in region between the stria medullaris and fornix. Double-labeled cells were also observed in small amounts in the dorsal parts of supraoptic nuclei, the ventral parts of anterior hypothalamic regions and lateral hypothalamic areas. In addition, a few double-labeled cells were seen in the subependymal area of the interventricular foramen (IVF) and in the floor of the 3rd ventricle. Our results demonstrate that CCK-ir nerve fibers in the posterior pituitary originate from more widespread hypothalamic areas than generally assumed. The fact that some CCK-ir neurons projecting to the posterior pituitary were located close to cerebrospinal fluid suggests that they may play a role in monitoring and controlling changes of cerebrospinal fluid.
Arachidonyl trifluoromethyl ketone, a potent inhibitor of 85-kDa phospholipase A2, blocks production of arachidonate and 12-hydroxyeicosatetraenoic acid by calcium ionophore-challenged platelets.
Arachidonyl trifluoromethyl ketone (AACOCF3) is a potent and selective slow binding inhibitor of the 85-kDa cytosolic phospholipase A2 (cPLA2) (Street, I. P., Lin, H.-K., Laliberté, F., Ghomashchi, F., Wang, Z., Perrier, H., Tremblay, N. M., Huang, Z., Weech, P. K., and Gelb, M. H. (1993) Biochemistry 32, 5935-5940). AACOCF3 and a number of its structural analogues have been used to investigate the role of cPLA2 in the cellular generation of free arachidonic acid (AA) and in eicosanoid biosynthesis. AACOCF3 inhibited the release of AA from calcium ionophore-challenged U937 cells (IC50 = 8 microM, 2 x 10(6) cells ml-1) and from platelets (IC50 = 2 microM, 4 x 10(7) cells ml-1). Arachidonyl methyl ketone (AACOCH3) and AACH(OH)CF3, both of which are noninhibitory to the purified cPLA2, did not inhibit the production of AA in the ionophore-challenged cells. In addition to the release of AA, AACOCF3 also inhibited the production of 12-hydroxyeicosatetraenoic acid (12-HETE) and thromboxane B2, two of the major metabolites of AA produced by platelets. The inhibition of 12-HETE biosynthesis showed a dose dependence similar to that of AA release in ionophore-challenged platelets; however, when platelet 12-HETE production was stimulated with 10 microM AA to circumvent the PLA2-dependent step, AACOCF3 no longer inhibited the production of 12-HETE. In contrast, AACOCF3 blocked thromboxane B2 formation by both calcium ionophore- and AA-challenged platelets, indicating that the compound affects the cyclooxygenase pathway in addition to AA release. The crude cytosol and membrane fractions from platelets were assayed for calcium-dependent and calcium-independent PLA2 activities and for the susceptibility of each to inhibition by AACOCF3. At AACOCF3 concentrations as high as 10 mol %, only one of the observed PLA2 activities was inhibited by more than 25%. The AACOCF3-susceptible PLA2 (77% inhibition at 1.6 mol %) was found in the cytosolic platelet fraction and showed the functional characteristics of the cPLA2. These results suggest that the cPLA2 plays an important role in the generation of free AA for 12-HETE biosynthesis in platelets.
Normal-state transport properties of YBa2Cu3O7- delta /PrBa2Cu3O7- delta superlattices.
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