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Biomedical subjects

Z Luo

Publications and source records attributed to Z Luo.

At least 163 records · Page 9Linked to original sources

[The experience in applying bovine pericardial patch in the correction of tetralogy of Fallot].

From January 1982 to December 1994, 432 patients with tetralogy of Fallot underwent the corrective operation. We extended the right ventricular outflow tract (RVOT) in 271 of the patients by using bovine pericardial patch treated by glutaraldehyde. The results were satisfactory. We emphasize that bovine pericardial patch is good material for extending RVOT, because it has many merits including high intensity, satisfied suture, no leakage, and abundant supply. Long-term follow up (maximum 12 years and 3 months) showed no ventricular aneurysm due to the degeneration of bovine pericardial patch.

Adolescent↗

Analysis of Tcrvb8, Il4, and Ifg as genetic predisposition factors for atopic IgE response in a murine model.

Allergen-induced synthesis of lgE Abs in genetically predisposed individuals constitutes the hallmark of allergic diseases; however, the molecular basis of this genetic predisposition remains unknown. T cell cytokines lL-4 and IFN-gamma reciprocally regulate lgE synthesis and are potential genetic factors governing atopy. To examine the inheritance patterns of IgE responsiveness and address the role of these cytokines as genetic predisposition factors, in this study we established a MHC-identical mouse colony comprising crosses between two inbred strains of mouse, A.SW and SJL, respectively representing high and low IgE responder phenotypes. Segregation analysis with 149 [(A.SW x SJL)F1 x SJL] backcross and 148 [(A.SW x SJL)F1 x F1]F2 mice suggested that persistent high IgE responsiveness was inherited as a simple Mendelian dominant trait under the control of a single non-MHC, autosomal gene of major effect in these strains. Since SJL lacked Tcrvb8 genes, we examined the possibility of Tcrvb8 as a candidate gene for IgE responsiveness. The results suggested association of neither the Tcrvb8 gene nor its expression with allergen-induced IgE phenotype. Furthermore, microsatellite marker and gene sequencing analyses revealed that neither of the ll4 and lfg genes was associated with IgE phenotype. Moreover, correlation studies between IgE and cytokine levels in splenocyte cultures indicated that IgE levels were moderately to poorly correlated with IL-4 and IFN-gamma levels. It is concluded that even though expression of Tcrvb8, II4, and Ifg genes may play pivotal roles in IgE regulation, these genes per se do not contribute to genetic predisposition of allergen-induced IgE hyperresponsiveness in these strains of mice.

Animals↗

Macrophage inflammatory protein-1 alpha enhances growth factor-stimulated phosphatidylcholine metabolism and increases cAMP levels in the human growth factor-dependent cell line M07e, events associated with growth suppression.

The immunoregulatory C-C chemokine, macrophage inflammatory protein-1 alpha (MIP-1 alpha) has suppressive activity on proliferation of stem cells and early subsets of myeloid progenitor cells. A receptor for C-C chemokines that binds MIP-1 alpha has been characterized, cloned, and shown to be related structurally to neuropeptide receptors that couple through G-proteins to phospholipase-C and adenyl cyclase. Yet, very little information on the intracellular mechanisms of action of MIP-1 alpha is available. We show here that the human factor-dependent cell line M07e is responsive to the cell cycle-suppressive effects of MIP-1 alpha, has specific membrane-binding sites for MIP-1 alpha, and that treatment of these cells with this chemokine increases the phosphatidylcholine (PC) and phosphocholine turnover rates in cells that are synergistically stimulated by the combination of granulocyte-macrophage colony-stimulating factor and steel factor but not these factors acting singly. Additional, MIP-1 alpha treatment induces a dose- and time-dependent increase in intracellular cAMP levels in M07e cells. Both exogenous PC and dibutyryl cAMP were found to suppress the proliferation of M07e colony-forming cells to a level similar to that of MIP-1 alpha, further implicating cAMP and PC metabolism in MIP-1 alpha-induced M07e suppression. RANTES, a related chemokine, with weak or incomplete binding to the cloned MIP-1 alpha receptor, did not suppress M07e colony-forming cells, nor did it increase intracellular cAMP levels, but it did enhance growth factor-induced PC turnover, further supporting the involvement of cAMP in MIP-1 alpha suppression while demonstrating that increased PC turnover alone is not sufficient for suppression. These findings support the idea that the human MIP-1 alpha receptor is coupled to phospholipid and cAMP metabolism in a manner similar to other 7-transmembrane, G-protein-linked receptors and suggest that a phosphatidylcholine hydrolytic cycle and an associated increase in cAMP are part of the mechanisms of action of MIP-1 alpha.

Bucladesine↗

Synergistic induction of phospholipid metabolism by granulocyte-macrophage colony stimulating factor and steel factor in human growth factor-dependent cell line, M07e.

Steel factor (SLF), the ligand for the c-kit proto-oncogene tyrosine kinase receptor, synergizes with several hematopoietic growth factors to produce greatly enhanced proliferation of normal human hematopoietic progenitor cells as well as that of the human growth factor-dependent myeloid cell line, M07e. The mechanisms of this phenomenon remain unknown. In an attempt to understand the cellular processes relevant to this phenomenon, we examined the effects of SLF and granulocyte-macrophage colony-stimulating factor (GM-CSF) on induced lipid metabolism in M07e cells. We find that both GM-CSF and SLF induced increased phosphatidylcholine (PC) turnover rates (biosynthesis and degradation) as measured by increased [3H]-choline labelling, with SLF being more potent than GM-CSF after 6 h of stimulation, but equipotent at 24 h of stimulation. The labelling of aqueous intermediates of PC metabolism was also increased by cytokine stimulation, most notably phosphocholine. Simultaneous stimulation with GM-CSF plus SLF resulted in a true synergistic induction of PC, lysoPC, and phosphocholine labelling. GM-CSF and SLF each induced asymmetric labelling of various phospholipid classes as measured by incorporation of different [3H]-fatty acids. [3H]-myristic acid labelling of phosphatidylserine was most prominently induced (approximately 12-fold). Cytosolic choline kinase activity was also upregulated more than twofold over control by SLF, which might contribute to the increased phosphocholine labelling. These effects may have relevance to the intracellular mechanisms of the synergistic proliferative stimulation of SLF plus GM-CSF on M07e cells.

Arachidonic Acid↗

Translational regulation in response to changes in amino acid availability in Neurospora crassa.

We examined the regulation of Neurospora crassa arg-2 and cpc-1 in response to amino acid availability.arg-2 encodes the small subunit of arginine-specific carbamoyl phosphate synthetase; it is subject to unique negative regulation by Arg and is positively regulated in response to limitation for many different amino acids through a mechanism known as cross-pathway control. cpc-1 specifies a transcriptional activator important for crosspathway control. Expression of these genes was compared with that of the cytochrome oxidase subunit V gene, cox-5. Analyses of mRNA levels, polypeptide pulse-labeling results, and the distribution of mRNA in polysomes indicated that Arg-specific negative regulation of arg-2 affected the levels of both arg-2 mRNA and arg-2 mRNA translation. Negative translational effects on arg-2 and positive translational effects on cpc-1 were apparent soon after cells were provided with exogenous Arg. In cells limited for His, increased expression of arg-2 and cpc-1, and decreased expression of cox-5, also had translational and transcriptional components. The arg-2 and cpc-1 transcripts contain upstream open reading frames (uORFs), as do their Saccharomyces cerevisiae homologs CPA1 and GCN4. We examined the regulation of arg-2-lacZ reporter genes containing or lacking the uORF start codon; the capacity for arg-2 uORF translation appeared critical for controlling gene expression.

Amitrole↗

The time course of myosin light-chain phosphorylation in blood-induced vasospasm.

The phosphorylation of an M(r) 20,000 myosin light chain (MLC20) promotes the generation of contractile force through actin-myosin adenosine triphosphatase in most agonist-mediated vascular smooth muscle cell contraction. However, the role of calcium-mediated contractile processes in sustained arterial narrowing after subarachnoid hemorrhage remains unknown. In a femoral artery model of vasospasm, whole blood was applied to arteries in 54 rats for periods of 2 to 10 days; the contralateral artery treated with platelet-rich plasma served as matched control. During the early stage of vasospasm (Days 2-5), in the media of arteries exposed to blood, MLC20 phosphorylation (including diphosphorylated forms) increased significantly (30-38%; P < 0.05); total medial MLC20 during this interval was comparable to that in controls. After 5 days, however, total MLC20 decreased markedly (> 90%; P < 0.01) compared with controls; phosphorylated MLC20 was undetectable during this interval. MLC20-mediated contractile processes may be prominent in the early stages of arterial narrowing after subarachnoid hemorrhage; later stages are associated with the loss of MLC20 and the possible persistence of arterial narrowing by other mechanisms.

Animals↗

Antioxidant and iron-chelating agents in cerebral vasospasm.

Prior work in our laboratory showed that the perivascular application of deferoxamine (an antioxidant and iron-chelating agent) inhibited delayed arterial narrowing after chronic blood exposure in a rat femoral artery model of vasospasm. To determine which of these mechanisms was operant in vasospasm, we compared deferoxamine with two agents (ascorbic acid and U74389F) that have antioxidant but not iron-chelating capacity. For the systemic application of drugs in 23 rats, whole blood encased in a silastic cuff was applied to the right femoral artery of each rat; whole-blood serum (lacking erythrocytes) was similarly applied to the left femoral artery. Deferoxamine (30 mg/kg/d), ascorbic acid (1000 mg/kg/d), U74389F (30 mg/kg/d), or pH-matched control vehicle was administered three times daily by intraperitoneal injection for 7 days. After exposure to whole blood, arteries treated with intraperitoneal vehicle showed an 85% reduction in the lumen, compared with vessels exposed to erythrocyte-free serum (P < 0.001). Intraperitoneal ascorbic acid and U74389F produced moderate amelioration in arterial narrowing (53 and 61% decrease, respectively, in the lumen versus controls; P < 0.05 versus vehicle); deferoxamine had no significant effect when administered intraperitoneally. To test the efficacy of these agents by the perivascular application of drugs, whole blood was applied to both femoral arteries in each of 25 rats. Solutions of deferoxamine (10 mg/ml), ascorbic acid (50 or 100 mg/ml), or U74389F (15 or 30 mg/ml) were directly applied to the perivascular thrombus surrounding the femoral arteries, compared with vehicle applied to contralateral vessels. The perivascular application of 50 mg of ascorbic acid (36% reduction, P < 0.05), 100 mg of ascorbic acid (31% reduction, P < 0.01), or 10 mg of deferoxamine (41% reduction, P < 0.05) significantly inhibited arterial narrowing, compared with vehicle. The application of U74389F at a dose of 15 or 30 mg directly into the perivascular thrombus produced nonsignificant reduction in arterial narrowing. These data suggest that mechanisms other than direct iron toxicity, such as generation of cytotoxic free radicals, may play an important role in cerebral vasospasm. In addition, the route of administration and concentration of drugs in the perivascular region adjacent to the thrombus may be critical to their efficacy.

Animals↗

[Antidepressant active constituents in the roots of Morinda officinalis How].

Five compounds having antidepressant activities have been isolated from the roots of Morinda officinalis, a Chinese traditional Yang-tonic drug. These compounds were identified as succinic acid (1), nystose (2), 1F-fructofuranosylnystose (3), inulin-type hexasaccharide (4) and heptasaccharide (5) by chemical and spectroscopic methods. All of the compounds are isolated from the species of genus Morinda for the first time.

Animals↗

Radiation inhibition of intimal hyperplasia after arterial injury.

To demonstrate the effect of gamma radiation on proliferating smooth muscle cells in vivo, a standardized bilateral carotid balloon catheter arterial injury was produced in 45 rats and doses from 0-20 Gy were delivered to the right carotid artery at 24 h after injury. At 20 days after injury, cross-sectional area of intima was determined from axial histological sections. Compared to contralateral, nonirradiated balloon-injured arteries, radiation produced a significant dose-dependent reduction in intimal cross-sectional area, with a 50% decrease at 5-7.5 Gy. To determine the effect of timing of irradiation on intimal hyperplasia, 30 rats with bilateral carotid injury received unilateral cervical irradiation at doses of 1, 5 or 10 Gy administered at either 1, 3 or 5 days after injury. The radiation dose (P = 0.0002), timing of irradiation (P = 0.003) and an interaction between timing and dose (P = 0.0278) were significantly associated with reduction in neointimal cross-sectional area. To determine the effects of radiation on intimal hyperplasia at later intervals, rats irradiated with 15 (n = 5) or 20 Gy (n = 5) were euthanized at 3 months after injury. A significant persistent reduction in intimal cross-sectional area for irradiated arteries at 3 months was associated with minimal apparent radiation effects upon adjacent tissue. These data suggest that external gamma irradiation at the single doses used effectively inhibits smooth muscle proliferation and intimal hyperplasia in the rat balloon catheter injury model in a time- and dose-dependent manner.

Angioplasty, Balloon↗

[A study on the effective way and dosage of intravas deferens injection of HFMC for male contraception].

To investigate the effective way and dosage of intravas deferens injection of HFMC for male contraception, Teflon tubes of 1 mm caliber were used to imitate intravas injection of HFMC. We injected HFMC first, then the precipitant; thus HFMC could adhere to the walls and blend with the precipitant to precipitate. Eight adult male rabbits, exposed reproductive ducts were injected with dyed HFMC in opposite directions (upward and downward), HFMC flowed out of the distal end of the vas easily when its volume was more than that of the vas. 14 adult rabbits were used for the comparison of sperm density and fertility index between upward and downward injections of HFMC, and between the dosage of HFMC (50 microliters and 100 microliters) injected upward. The results show that it is difficult to attain contraception by intravas injection of HFMC downward, but contraception is quite possible by intravas injection of HFMC upward providing the volume is enough. The result also suggest that HFMC should be injected into vas deferens upward first; its volume should be 3 time as much as the natural volume of the vas from the injecting point to the epididymal end. Then a little precipitant is injected into the vas.

Animals↗

[Clinicopathologic analysis of ependymoma in childhood].

A review of the clinicopathologic features of 23 ependymomas in children was made, of which 17 were male and 6 female, the male:female ratio being 2.8:1. Their average age was 8.8 years. Seven of the 23 ependymomas were supratentorial, 16 were infratentorial. The mean duration of symptoms prior to operation in the two groups was 5.3 and 3 months respectively. Histologically, the tumor could be classified into three types: papillary (or myxopapillary), epithelial and cellular. According to the degree of differentiation, the tumor could be divided into typical ependymoma and anaplastic ependymoma. Immunohistochemically, 17 of the 23 cases were positive for glial fiber acid protein (GFAP) and the remaining 6 cases were negative. The clinicopathologic features of childhood ependymomas, factors influencing prognosis and histologic classification are discussed.

Adolescent↗

Regulation of acetylcholinesterase mRNA stability by calcium during differentiation from myoblasts to myotubes.

The expression of acetylcholinesterase (AChE), nicotinic acetylcholine receptors (nAChR), and their corresponding mRNAs increases dramatically during the conversion of myoblasts to myotubes in C2-C12 cells. The increase in expression of nAChR arises from transcriptional activation of the genes encoding the receptor subunits, whereas stabilization of labile transcripts is primarily responsible for enhanced AChE expression. In a search for the signaling pathways responsible for stabilization of the AChE mRNA, we found that ryanodine, synthetic ryanodine receptor antagonists and L-type, but not N-type, Ca2+ channel blockers inhibit the differentiation-induced expression of AChE mRNA, but not the nAChR mRNA. Selective inhibition of increased expression of AChE is also evident. Inhibition by ryanodine and nifedipine is additive suggesting different target sites for the two Ca2+ channel ligands. Ryanodine binding sites can be detected in both myoblasts and myotubes, but they increase substantially during differentiation. Rates of AChE gene transcription are not altered by ryanodine and nifedipine, indicating that decreased Ca2+ availability prevents stabilization of the mRNA normally seen with differentiation. Muscle cells still undergo elongation and fusion in the presence of ryanodine or L-type Ca2+ channel antagonists. Ryanodine block is fully reversible, indicating functional integrity of the cellular expression system after the drug treatment. These findings indicate that intracellular ryanodine-sensitive calcium channels and extracellular L-type Ca2+ channels link to play an important role in stabilizing AChE mRNA and suggest that transient increases in intracellular Ca2+ may be critical for the commitment of AChE expression during myogenesis.

Acetylcholinesterase↗

A peptide C-terminal to the second Zn finger of human vitamin D receptor is able to specify nuclear localization.

A peptide of 27 amino acids, VDR(102-76), representing residues 76-102 immediately C-terminal to the second Zn finger of human vitamin D receptor (hVDR) was conjugated to fluorescein-labelled IgG using a bifunctional coupling reagent, m-maleimidobenzoyl n-hydroxysuccinimide. Upon microinjection into the cytoplasm of human osteosarcoma MG-63 cells, the chimeras accumulated in the nuclei. This transport was arrested by chilling or energy depletion. Two other peptides, VDR(80-67), spanning the N-terminal part of VDR(102-76), and VDR(108-97), spanning the C-terminal part of VDR(102-76), were not able to target the linked proteins to the nuclei. SV40(135-112), a peptide containing a well-characterized nuclear localization sequence (amino acids 112-135) of simian virus 40 (SV40) large T-antigen, caused complete nuclear accumulation under the same conditions. Wheat germ agglutinin, which inhibits SV40(135-112) transport, also inhibited the nuclear accumulation of VDR(102-76) as did energy depletion.

Amino Acid Sequence↗

Structural determinants of cytochrome P450 2B1 specificity: evidence for five substrate recognition sites.

Twelve site-directed mutants of rat cytochrome P450 2B1 distributed over seven positions and four putative substrate recognition sites (SRS) were constructed and expressed in COS cells. Function was examined using androstenedione and testosterone as substrates. Substitutions at positions 303, 360, and 473 did not markedly affect the regio- or stereoselectivity of androgen metabolism, whereas mutants in positions 206 (SRS-2), 302 (SRS-4), and 363 and 367 (SRS-5) exhibited markedly different steroid metabolite profiles compared with parental P450 2B1. In particular, the Phe-206-->Leu substitution conferred androgen 6 alpha- and testosterone 7 alpha-hydroxylase activities, and the Thr-302-->Ser substitution suppressed androgen 16 beta-hydroxylation in favor of androstenedione 16 alpha- and testosterone 15 alpha-hydroxylation. Replacement of Val-363 or Val-367 with Ala conferred androgen 15 alpha-hydroxylase and 6 beta-hydroxylase activities, respectively, and suppressed susceptibility to mechanism-based inactivation by the P450 2B1-selective chloramphenicol analog N-(2-p-nitrophenethyl)chlorofluoroacetamide. The Val-367-->Ala mutant was also resistant to chloramphenicol itself. The Leu mutant at position 363 exhibited increased specificity for androstenedione and testosterone 16 beta-hydroxylation, whereas the Leu mutant at position 367 exhibited decreased stereospecificity. Most interestingly, the size of key residues identified plays a critical role in governing steroid hydroxylation from the alpha-face or beta-face and hydroxylation on the D-ring or the B-ring.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

Role of residues 363 and 206 in conversion of cytochrome P450 2B1 from a steroid 16-hydroxylase to a 15 alpha-hydroxylase.

Four double and four triple site-directed mutants of cytochrome P450 2B1 were constructed, expressed in COS cells, and assayed for androstenedione and testosterone hydroxylation. The mutants combined a Val-363-->Ala substitution with an Ile-114-->Val or Ala substitution and/or a Gly-478-->Ala or Ser substitution. Each of the individual mutations enhances androgen 15 alpha-hydroxylation, and the appropriate combination of Val or Ala at position 114 with Ala or Ser at position 478 has recently been shown to convert P450 2B1 from an androstenedione and testosterone 16 beta-hydroxylase to a 15 alpha-hydroxylase (Halpert, J. R., and He, Y.-A. (1993) J. Biol. Chem. 268, 4453-4457). All eight mutants containing the Val-363-->Ala substitution preferentially hydroxylated androstenedione and testosterone in the 15 alpha-position and thus functionally resemble mouse P450 2A4. However, unlike P450 2A4, various single and multiple 2B1 mutants at positions 114, 363, and 478 mainly hydroxylated progesterone in the 16 alpha- rather than 15 alpha-position. By combining the Ile-114-->Ala substitution with a Phe-206-->Leu mutation (corresponding to Ala-117 and Leu-209 in P450 2A4), P450 2B1 was converted to a progesterone 15 alpha-hydroxylase with retention of testosterone 15 alpha-hydroxylase activity. These studies document the importance of residues 363 and 206 in determining the substrate specificity of P450 2B1 and strongly support the hypothesis that the judicious combination of a small number of discrete mutations can be used to confer new specificities on P450 enzymes.

Androstenedione↗

Expression and ligand specificity of acetylcholinesterase and the nicotinic receptor: a tale of two cholinergic sites.

The functional design of the nAChR and AChE rather than their recognition capacities requires divergence in structure of the two binding sites. The receptor requires co-operativity to link ligand occupation to the response, rapid conformational transitions of activation, and slower transitions of desensitization. Hence, its binding sites have evolved at subunit interfaces. By contrast, AChE functions with a large kcat and a comparatively large Km. To do so, it must force acetylcholine through a low-energy transition site that features tetrahedral rather than the ground-state, trigonal conformation around the carbonyl carbon. This requires a high affinity (KD approximately 10(-17) M) for the enzyme complex of the transient transition state. Interestingly, the three-finger peptide toxins (alpha-bungarotoxin and fasciculin), though closely homologous, use different interaction sites on the receptor (the agonist recognition site) and AChE (a peripheral site). Finally, although the two proteins show co-ordinated expression during muscle differentiation, the receptor relies primarily on transcriptional control while AChE expression is post-transcriptional, being controlled by mRNA stability.

Acetylcholinesterase↗

Association of USF and c-Myc with a helix-loop-helix-consensus motif in the core promoter of the murine type II beta regulatory subunit gene of cyclic adenosine 3', 5'-monophosphate-dependent protein kinase.

Previous studies showed that the core promoter of the mouse cAMP-dependent protein kinase regulatory subunit type II beta (RII beta) gene was composed of two functional elements. One element was GC rich and bound the Sp1 transcription factor. The second element contained a helix-loop-helix (HLH)-motif. Each element conferred transcriptional activity when inserted upstream of a reporter gene, chloramphenicol acetyltransferase and transfected into mouse NB2a neuroblastoma cells and Chinese hamster ovary (CHO) cells. The core promoter was further characterized by mutational analysis using electrophoretic mobility shift assays and by transfection into CHO and NB2a cells. Electrophoretic mobility shift assays showed that the HLH-consensus motif, CACGTG, present in the RII beta gene bound nuclear factors present in NB2a and CHO cells. Mutations in the HLH-core motif decreased the binding of these factors and reduced the transcriptional activity of constructs containing the chloramphenicol acetyltransferase reporter when transfected into these cells. The results showed that the central nucleotides as well as the adjacent bases were important for the interaction with the nuclear binding factors. UV cross-linking, Southwestern blot analysis, and interference of the mobility shift patterns by specific antisera directed against USF and c-Myc indicated that both of these transcription factors were forming complexes with the HLH-consensus motif. The results suggest that RII beta transcription may be regulated, in part, by USF and c-Myc in NB2a and CHO cells.

Animals↗

[Therapeutic effectiveness of zuzhongping on patients with arteriosclerostic cerebral infarction].

Forty-six patients with acute arteriosclerostic cerebral infarction were randomly divided into two groups: control group and treatment group. Each of them included 23 patients respectively. The patients in the control group were given Dextran-40 but the ones in the treatment group were given the mixture of Zuzhongping. The course of treatment was 3 weeks. It was found that there was a significant difference (P < 0.01) in the score percentage, before and after treatment of neurological defects, between the control group and the treatment group, and the former (29.70 +/- 33.52) was much lower than the latter (45.40 +/- 27.60). The total curative rate of the treatment group (87.0%, 20/23) was significantly higher than that of the control group (60.9%, 14/23). There was an obviously prolonged KPTT (kaolin partial thromboplastin time) value and a decreased Fb (fibrinogen) level in the treatment group. Before treatment they were 32.43 +/- 4.03 sec and 6.18 +/- 1.77 g/L respectively, but after treatment, 52.96 +/- 10.50 sec and 4.5 +/- 0.95 g/L respectively. The authors suggest that the significant therapeutic efficacy of Zuzhongping in the patients with acute arteriosclerostic cerebral infarction is related to its action of anticoagulation, modification of PGI2 and TXA2 level in the body, decreased blood Fb level, hyperglycemia, etc.

Aged↗