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Biomedical subjects

Z Ying

Publications and source records attributed to Z Ying.

65 records · Page 4Linked to original sources
PubMed1994

Enhanced expression of group II phospholipase A2 in human hepatocellular carcinoma.

Enzyme activity, protein contents, and mRNA contents of group II phospholipase A2 (PLA2) in hepatocellular carcinoma (HCC) surgically obtained from 8 patients were compared with those in either its neighboring liver tissues or control liver tissues. The PLA2 specific activity towards the mixed micelles of 1-palmitoyl-2-oleoyl-phosphatidylglycerol and cholate was significantly greater in the tumor tissues (6.62 +/- 1.46 nmol/min/mg) than those in the surrounding liver tissues (1.33 +/- 0.22 nmol/min/mg) and controls (0.43 +/- 0.04 nmol/min/mg). The results of immunoblot analysis using a specific anti-human group II PLA2 antibody and of Northern blot analysis using a human group II PLA2 cDNA as a probe demonstrated that group II PLA2 was responsible for the increased enzyme activity. The contents of immunoreactive group II PLA2 in the tumor tissues (8.81 +/- 1.24 ng/mg) were significantly higher than those in the surrounding liver tissues (1.74 +/- 0.27 ng/mg); those in the control tissues were below the analytical range of the method used. The group II PLA2 mRNA was also significantly increased in the tumor tissues, compared with that in the surrounding liver tissues, whereas it was not detectable in the controls. This indicates that group II PLA2 in HCC is induced at the pretranslational level.

Carcinoma, Hepatocellular↗
PubMed1994

Capsid assembly and involved function analysis of twelve core protein mutants of duck hepatitis B virus.

The roles of different regions of the duck hepatitis B virus (DHBV) core protein on viral capsid assembly and related functions were examined. Twelve deletion and insertion mutations which covered 80% of the DHBV C open reading frame were constructed and expressed in Escherichia coli. The N-terminal region (amino acids 3 to 66) of DHBV core protein was important for its tertiary structure and function in E. coli. The expressed core mutants without this region apparently inhibited E. coli growth. The results of transmission electron microscopy of E. coli thin sections, capsid agarose gel, and sucrose gradient sedimentation demonstrated that a few DHBV core mutants with insertion in the N terminus and deletion in the C terminus retained the ability to form core-like particles in E. coli. However, other mutations in most of N-terminal and central regions strongly inhibited the self-assembly ability of DHBV core protein in E. coli. In addition, the mutant with a C-terminal region deletion (amino acids 181 to 228) lost most of the nucleic acid-binding activity of the DHBV core protein.

Amino Acid Sequence↗
PubMed1993

Purification and characterization of guinea pig gastric phospholipase A2 of the pancreatic type.

Guinea pig gastric mucosa and juice contained exceptionally high phospholipase-A2 activity, whereas the activity in the pancreas was only minimal. Phospholipases A2 were purified to homogeneity from these three tissues. Structural evidence, including the sequence of the NH2-terminal 41 residues, the amino-acid composition and the molecular mass (13902 +/- 3 Da) determined accurately by mass spectrometry, showed that the gastric mucosa enzyme belongs to the pancreatic type. An unique feature of the sequence is the substitution of Phe for the hitherto invariant Tyr28 in the calcium-binding loop of pancreatic phospholipases A2. The affinity of the guinea pig enzyme for Ca2+ in the presence of substrate was, however, identical to that of the rat enzyme with Tyr28, suggesting the interaction of a phenolic hydroxyl group of the Tyr with its neighboring residues is not significantly linked to the binding of Ca2+. The NH2-terminal sequences and immunochemical properties of the enzymes purified from the gastric juice and pancreas were identical to those of the gastric mucosa enzyme. The distribution of cells immunoreactive with anti-(gastric PLA2) immunoglobulin in the stomach was quite similar to that of the chief cells. Unlike in pancreas of other animals, the prophospholipase A2 was not detectable in gastric mucosa or juice homogenates treated with diisopropyl fluorophosphate or in column effluents during purification under acidic conditions. An appreciable prophospholipase-A2-activating activity was not detectable in gastric mucosa extracts at low pH relevant to gastric juice, using rat prophospholipase A2 as substrate. This opposes the activation of secreted proenzyme in the gastric juice.

Amino Acid Sequence↗
PubMed1993

Cloning and expression of phospholipase A2 from guinea pig gastric mucosa, its induction by carbachol and secretion in vivo.

A cDNA encoding phospholipase A2 (PLA2) was cloned from guinea pig gastric mucosa using a rat pancreatic-PLA2-cDNA fragment as a probe. The cDNA contains an open reading frame sufficient to encode the entire amino-acid sequence of a PLA2-precursor protein consisting of 146 amino acids, including a putative 16-residue signal peptide and a 6-residue activation peptide at the NH2-terminus. Its nucleotide sequence exhibits 70% similarity to that of rat pancreatic PLA2 cDNA. The deduced amino-acid sequence has all the typical pancreatic PLA2 characteristics, with the exception of the substitution of Phe for Tyr at position 28 in the calcium-binding loop of the mature enzyme. When an expression vector containing the PLA2 cDNA was transfected into COS-7 cells, a major portion of the proenzyme was secreted into the culture medium. Northern-blot analysis showed the mRNA was present in guinea pig lung and pancreas at much lower levels than in the stomach. The effect of carbachol, a muscarinic acetylcholine agonist, on the secretion of gastric PLA2 and on its mRNA level in the gastric mucosa were examined. PLA2 secretion into the gastric juice was maximal 30 min after the subcutaneous administration of carbachol (0.4 mg/kg). It also increased the PLA2-mRNA level in the tissue, the maximal mRNA level being delayed about 15 min compared with that in PLA2 secretion. These results suggest that vagal stimuli may contribute to PLA2 secretion and its compensatory synthesis, and that the secreted PLA2 may participate in the digestion of dietary and biliary phospholipids in the small intestine of guinea pig.

Amino Acid Sequence↗
PubMed1992

Motor and somatosensory evoked potentials in coma: analysis and relation to clinical status and outcome.

Central sensory and motor conduction were studied in 23 comatose and three brain-dead patients. Motor evoked potentials (MEPs) to transcranial magnetic (magMEP) and electrical (elMEP) stimulation were recorded from the hypothenar muscle, and somatosensory evoked potentials (SEPs) were recorded after median nerve stimulation. Comparison of clinical with evoked potential (EP) findings revealed: 1) a painful stimulus applied to the skin of the arm lowered excitation threshold to cortical stimulation and was a prerequisite to obtain MEPs in 14 instances; 2) only in braindead patients were all EPs abolished simultaneously and bilaterally; 3) MEPs (p less than or equal to 0.05, chi 2-Test), but not necessarily SEPs (p greater than 0.1) were preserved in the arms that showed normal motor reaction during clinical examination; 4) no correlation was found between EP findings and the Glasgow Coma Scale (GCS). The results of clinical and EP testing were examined in the light of the patient's outcome 10 months later: 1) fatal outcome was predicted by a GCS of three (38% of cases, p less than or equal to 0.05, Fisher's exact test), abolished brainstem- or papillary reflexes (38%, p less than or equal to 0.05), the combination of these clinical signs (54%, p less than or equal to 0.01), bilateral abolition of elMEPs (38%, p less than or equal to 0.05), magMEPs (38%, p less than or equal to 0.05), or SEPs (23%, p greater than 0.1), or a combination of clinical and EP data (85%, p less than or equal to 0.0005); 2) good outcome was predicted by a GCS of greater than or equal to 8 only in post-traumatic coma, and EPs did not help to predict fatal outcome of coma; 1) if this appears impossible on the basis of clinical data alone; 2) if a second indicator is needed to confirm a clinical impression; 3) SEPs may be first evaluated during the acute stage of coma treatment, because they can be recorded in the presence of anaesthetic or relaxant agents; 4) MEP may be studied if outcome prediction remains ambiguous, and if the clinical situation allows for discontinuation of these agents.

Adolescent↗
PubMed1991

[Mapping in tumor surgery of the central region].

A prerequisite for successful operations of the central area is the exact pre- and intraoperative localization of the motor strip and the pyramidal tract. The craniocerebral landmarks--the coronal suture and bregma--and the central anatomy in the CT and the MRI favors their localization. According to the anatomical variations and the displacement of the brain by the lesion, these landmarks are not very reliable in identifying the central region in all cases. A safe intraoperative localization of the motor strip is possible with the combination of electrical cortical stimulation and recording of somatosensory evoked potentials. With these methods the results of operations of central lesions are good and the risk of severe postoperative morbidity is low.

Adult↗
PubMed1991

Molecular nature of aldosterone synthase, a member of cytochrome P-450(11 beta) family.

The molecular nature of the aldosterone synthesizing enzymes of cattle and rat is discussed. In bovine adrenal cortex, one molecular species of cytochrome P-450(11 beta) catalyzes aldosterone synthesis as well as 11 beta-hydroxylation. The intactness of the mitochondrial membrane surrounding P-450(11 beta) in the zonae fasciculata-reticularis is essential to keep the aldosterone synthesizing activity of the cytochrome in these zones latent. In rat adrenal cortex, two distinct molecules belonging to a P-450(11 beta) family exist. One is 11 beta-hydroxylase, and the other aldosterone synthase.

Adrenal Cortex↗
PubMed1990

Molecular cloning and expression of cDNAS encoding rat aldosterone synthase: variants of cytochrome P-450(11 beta).

Two distinct forms of cDNA encoding rat aldosterone synthase were cloned from an adrenal capsular tissue cDNA library. The deduced amino acid sequences showed that one of the enzymes (P-450(11 beta),aldo-1) had a long extension peptide composed of 34 amino acid residues while the other (P-450(11 beta),aldo-2) had an extension peptide identical to that of rat P-450(11 beta). Glu at the 320th position of P-450(11 beta),aldo-1 was replaced with Lys in P-450(11 beta),aldo-2. The amino acid sequence of the aldosterone synthase was highly homologous (81%) to rat P-450(11 beta). Constructed expression vector containing the cDNA for extension peptide of P-450(11 beta) and the mature protein of P-450(11 beta),aldo-1 was transfected into COS-7 cells. The cells converted 11-deoxycorticosterone into corticosterone, 18-hydroxycorticosterone, and aldosterone.

Amino Acid Sequence↗
PubMed1982

Phenotypic effects of inherited balanced translocation.

We report two cases of inherited balanced translocation with severe CNS abnormalities and a number of other physical findings. In both cases a multiple congenital anomalies/mental retardation (MCA/MR) syndrome was suspected. However, in one case, parturitional and neonatal complications probably resulted in brain damage; in the other, prenatal brain damage due to intoxication from a dead twin or porencephalic cysts due to vascular accidents remain unconfirmed hypotheses. It is concluded that no MCA/MR syndrome was present and that the inherited balanced translocation was a coincidental finding in these two brain-damaged, mentally retarded children.

Abnormalities, Multiple↗