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Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 883 records · Page 49Linked to original sources
PubMed1997

[The role of adenosine in the early stage of anoxia of hippocampal slices and its mechanisms].

The role of adenosine in reversible inhibition of synaptic function during the early stage of anoxia and its mechanisms were investigated with extracellular recording technique in rat hippocampal slices. The results showed that acute anoxia led to the reversible inhibition of synaptic function, which is similar to the response to addition of high concentration of exogenous adenosine. The reversible inhibition could be suppressed by adenosine A1 receptor antagonist CPT and potassium channel blocker 4-AP, whereas TEA and ATP-sensitive potassium channel blocker glipzide had no effect. These results suggest that during the early stage of anoxia, the enhanced release of endogenous adenosine can inhibit the synaptic transmission by activating 4-AP-sensitive potassium channels via A1 receptors and thus play a role in protenction against anoxic injury. ATP-sensitive potassium channels may not be involved in the mechanisms of adenosine action.

Adenosine↗
PubMed1997

[Role of Na+/Ca2+ exchange blocker in rat hippocampal injury during anoxia].

Effects of Na+/Ca2+ exchange blocker, Benzamil, on rat hippocampal slices and on cultured hippocampal neuronal [Ca2+]i (intracellular free Ca2+ concentration) during anoxia were investigated by means of microelectrode recording technique and laser scanning confocal microscope respectively. The results showed that the PV sustained time of hippocampal slices pretreated with Benzamil (50 mumol) after anoxia was markedly longer than that of control, suggesting that inhibition of Na+/Ca2+ exchange can delay the irreversible injury to hippocampal cells. Moreover, by using a confocal microscope we found that acute anoxia induced a rapid increase of [Ca2+]i in hippocampal neurons and this could be significantly attenuated by 20 mumol Benzamil. All these results indicate that Na+/Ca2+ exchanger is involved in the anoxic injury to rat hippocampus and it may be one of the major ways leading to the anoxia-induced [Ca2+]i increase of hippocampal neurons.

Amiloride↗
PubMed1997

[Effects of different components of serum from radiation, burn and combined radiation-burn injury on L-type calcium channel of cultured myocardial cells].

The effects of different components of serum from radiation, burn and combined radiation-burn injury on the activity of L-type calcium channel in cultured myocardial cells were investigated in this study. The results revealed that the serum from different injury groups could all activate the L-type calcium channel of cultured myocardial cells. These changes altered the calcium level in cells, which might be an important cause of dysfunction in cardiovascular system. Among the components of postinjury serum, the effect of high molecular components (> 8-10 kD) was not significant, whereas low molecule (< 8-10kD) and lipid components were the major effective components. The low molecule of postinjury serum affected not only on the opening activity of L-type channel, but also on the state of molecular movement in the membrane. The effect of serum lipids from injury groups could be depressed by SOD, which suggests that there may be free radical reactions during the serum lipids effect on calcium channel. The effects of serum and its components from combined radiation-burn group were the most intensive, and those from radiation injury were the weakest. The nature of the toxic material in serum remains to be further investigated.

Animals↗
PubMed1997

[Anoxia-induced c-fos expression of cultured rat hippocampal neurons and effect of recombinant human interleukin-1 beta].

Effects of recombinant human interleukin-1 beta (rhIL-1 beta) on the c-fos expression of cultured rat hippocampal neurons in vitro induced by anoxia were studied by using an immunohistochemical method. The results showed that the percentage and the mean optical density of the Fos-positive neuronal nuclei in cultured hippocampal neurons increased markedly as anoxia prolonged, while those in hippocampal neurons pretreated with rhIL-1 beta were significantly lower than those of control. The results indicate that anoxia can induce c-fos expression of cultured rat hippocampal neurons in vitro and this can be inhibited by rhIL-1 beta, suggesting that rhIL-1 beta may protect neurons from damage in a certain degree during anoxia.

Animals↗
PubMed1997

[Predictive value of IL-2R in renal tissue during acute renal allograft rejection].

The pattern of intragraft immunological events associated with acute cellular rejection (ACR) has been previously defined. We conducted a retrospective longitudinal study to compare the clinical significance of various immunological markers in renal materials obtained from human renal allografts. Three to 6 consecutive allograft biopsies were obtained from 17 serial human transplant recipients over an 8-month period. A total of 59 core needle biopsies were examined. The expression of interlukin-2 receptor (IL-2R) in interstitial infiltrates, as well as the presence of CD4/CD8 T cell infiltrates were assessed by immunocytochemical staining of frozen sections. When ACR occurred, IL-2R expression increased about 16.3 fold in the renal specimens significantly as compared with those specimens without ACR. After MTX-pulse therapy the expression of IL-2R in biopsies were evidently down-regulated about 60%. The results suggested that the expression of IL-2R in renal allograft may be a useful and helpful adjunct in the diagnosis of ongoing acute cellular rejection, and decrease in these expression may be indicative of successful antirejection therapy.

Adult↗
PubMed1997

[A self-designed crooked suturing needle anastomosis in the treatment of posterior urethral strictures or occlusions].

A self-designed crooked suturing needle was described and has been used in the surgical treatment of complicated posttraumatic posterior urethra strictures or occlusions in 27 cases from Mar. 1986 to Feb. 1996. 1-stage transperineal end to end anastomosis of the bulbomenbranous urethra to the prostatic urethra with indeed healthy mucosa to healthy mucosa after scar tissue had been excised was performed with the above mentioned crooked suturing needle. 27 patients were followed up for 3 months to 9.5 years after operation with a satisfactory result of 100% and all voided freely with no sound urethral dilation and no trouble after the removal of the catheter. The erect dysfunction of 5 of the patients after the operation within 1-5 years restored completely.

Adolescent↗
PubMed1997

[Angiotensin-converting enzyme gene polymorphism and the clinical pathological features and progression in lupus nephritis].

The renin-angiotensin system (RAS) is now well established as an important determinant in the progression of renal damage. The level of plasma angiotensin converting enzyme (ACE) is genetically determined and this gene effect is associated with insertion (I)/deletion (D) polymorphism in intron 16 of ACE gene. It has been reported that DD genotype of ACE gene is associated with a poor outcome in patients with IgA nephropathy and trend to develop renal damage in diabetic mellitus. In this study, the correlation between ACE gene I/D polymorphism and the clinical features of lupus nephritis (LN) was determined in 144 LN patients and 150 normal controls by PCR. 72 LN patients were followed up for more than two years. It was found that the DD genotype was significantly higher in LN patients than in normal controls (P < 0.01), while the II genotype was much less in LN (P < 0.01). There was no significant difference in DI genotype frequency between LN patients and normal control (P > 0.05). Patients with hematuria, type IV LN, activation of LN, crescentic formation and severe tubulo-interstitial lesions showed an excess of the DI genotype. However, the DD genotype was not associated with the clinical and pathological characteristics of LN. To assess whether ACE genotype influence the progression of LN, we compared the clinical and pathological findings in patients of different genotype subgroups. There was no significant difference in blood pressure, proteinuria, serum creatinine, active index of disease and crescentic formation at presentation among these groups. However, as patients were divided into two groups according to their rate of decline in renal function. We found that patients with progressive renal function damage had a higher frequency of DI genotype than those with stable renal function (P < 0.01). It is conclude that patients with LN the DI genotype was associated with the severity and the poor prognosis in patients with LN.

Adolescent↗
PubMed1997

[Detection of herpes simplex viral genome in normal cornea].

OBJECTIVE: To determine whether herpes simplex virus (HSV) is present in normal cornea. METHODS: HSV genome in 22 corneas from donors without the history of herpes simplex keratitis (HSK), 6 positive control corneas from patients with active herpetic keratitis and 6 negative control corneas from embryos was detected by using polymerase chain reaction (PCR). RESULTS: HSV DNA was present in 20 of 22 normal corneas, and no viral genome was detected in any of the embryonic corneas. All the corneas from patients with active herpetic keratitis showed positive PCR results. CONCLUSIONS: The results indicate that the HSV genome is present in some normal corneas, that is concordant with the seropositive rate of HSV in people.

Adult↗
PubMed1997

[Treatment of congenital eyelid syndrome (CES)].

According to our observation and treatment on 21 CES cases, they could be divided into two types, and the distinction was the developing condition of palpebral tissues. Beside the two stage technique to treat 13 CES cases, the one stage technique was also used to treat 8 CES cases by modification of the management of medial canthal ligament, e.g. partially shortening the lateral part of the superficial head of medial canthal ligament. The key is the amount of the horizontal tension of upper eyelid subsequent to medial canthoplasty. The follow-up time was 7 years. Comparing the pre- and post-operative examination results of both one stage and two stage techniques, it was shown that both of them could achieve the goals of enlarging the eyelid fissure and completely elevating the upper eyelid.

Adult↗
PubMed1997

[The expression of rat brain constitutive nitric oxide synthase in NG108-15 cell].

Full length cDNA of rat brain cNOS was inserted into the polylinker area of pRC/CMV with specific orientation and an eukaryocyte expression vector pCMVcNOS was obtained. The existence of cNOS gene was demonstrated by PCR amplification, using pCMVcNOS gene as the model and primers designed in accord with the internal sequence of cNOS gene. The insertion and orientation of pCMVcNOS were further verified by enzymatic cleavage. NG108-15 cells were transfected with pCMVcNOS by calcium phosphate DNA coprecipitation and lipofectin transfection. G418 resistant monoclonal cells were selected with a culture medium containing 600 micrograms/ml G418. NOS activity of each clone was assayed by monitoring the conversion of 3H-Arginine to 3H-Citrulline. High expression cell lines were selected through measurement of the cytosol and particulate NOS activity. Out of 42 resistant monoclonal cell lines, 3 stable high expression clones have been finally selected. The increase of expressed cytosol NOS was more obvious. The result showed that the cell lines expressing cNOS at a high level had been obtained.

Animals↗
PubMed1997

[Optimazation of conditions for stereoselective reaction by enzyme-catalyzed acetylation].

Optically active endo-tricyclo-[5,2,1, 0(2,6)]deca-8-en-3,5-diol-5-acetate is a very useful chiral synthon for the synthesis of optically active natural products. In this paper, the optimal conditions for the synthesis of this compound was established by orthogonality test. Under these conditions, the chemical percentage yield of acetylation of (+) endo-tricyclo-[5,2,1,0(2,6)] deca-8-en-3,5-diol-5-acetate and its % e.e. can reach up to 81% and 98.3% respectively. The optimazation of the conditions is efficient for the reaction of enzyme-catalyzed esterification.

Acetylation↗
PubMed1997

[Kidney lesions complicated by hypoxic ischemic encephalopathy of neonatal pig].

To study the kidney lesions complicated by hypoxic ischemic encephalopathy (HIE) in newborn, we successfully established a neonatal pig model of HIE. Changes in brain tissue similar to those of newborn in HIE were detected after 2 hours of hypoxia and ischemia. Meanwhile, swelling of kidneys, hemorrhage below encapsules, swellin of tubular epithelial cells, necrosing and falling of a few tubular epithelial cells, and narrowing of tubular lumens were observed. The basement membranes of renal tubules remained normal serum BUN and creatinine increased significantly after experiment compared with before (P < 0.025 and P < 0.05 respectively). The results showed that the kidney of neonatal pig was damaged in HIE. But the injury was not severe. After 72 hours free from hypoxia, the structure and function recovered approximately from the injury.

Animals↗
PubMed1997

[The vascular pattern of the endolymphatic duct, endolymphatic sac and its anatomic differences in guinea pigs].

In order to study the vascular pattern of the endolymphatic duct and sac, endolymphatic duct and sac were examined with vascular Indian ink injection and image analysis. The Results were as follows: 1. In the 20 temporal bones, 17 (85%) had posterior meningeal artery (PMA) and posterior vestibular artery (PVA) supply and the rest (3 specimens, 15%) had no PVA supply; 2. The distribution frequency of PMA in the endolymphatic sac was much higher than that of PVA(P < 0.01), but the distribution of PMA and PVA in the endolympatic duct were not different (P > 0.05). The conclusions is that there are anatomic differences in vascular supply and pattern of the endolymphatic duct and sac, PMA is the main vascular structure in the endolymphatic sac.

Animals↗
PubMed1997

[Nuclear matrix protein pattern in human hepatocellular carcinoma].

OBJECTIVE: To compare nuclear matrix proteins of normal liver with those of hepatocellular carcinoma (HCC) to see whether there are HCC-specific proteins. METHODS: Using high resolution two-dimensional polyacrylamide gel electrophoresis, the nuclear matrix proteins of 3 normal livers and 8 HCC were compared. RESULTS: There was a high degree of similarity between nuclear proteins of normal liver and those of HCC. Four HCC-specific nuclear matrix proteins were identified. Among them, one protein(Mr: 62,000; pI: 5.3) appeared in all tumor samples. The other three proteins appeared in most of the 8 HCC cases. These proteins were not detected in 3 normal livers. CONCLUSION: There are HCC-specific nuclear matrix proteins which may be related to the etiology and pathogenesis of HCC.

Antigens, Nuclear↗
PubMed1997

[The scavenging system designed for inhaled nitric oxide].

Inhaled nitric oxide must take care of the potential adverse effect of nitric oxide and higher oxides of nitrogen (nitric dioxide and others. So we designed this three stages scavenging system to satisfy the demand of inhaled nitric oxide and prevent environmental contamination.

Equipment Design↗
PubMed1997

[A preliminary report of epikeratophakia for the treatment of Terrien's degeneration].

PURPOSE: To evaluate the efficacy of epikeratophakia for the treatment of severe Terrien's degeneration. METHODS: Four eyes with severe Terrien's corneal degeneration are studied. The lesions were located at the peripheral cornea and the corneal thickness was less then 1/3 of normal. Plano keratoplasty was performed. A lamellar lenticule with a 2 mm scleral rim was grafted on the cornea of which the epithelium had been removed. Keratometry and cycloplegic refraction were performed pre- and post-operatively. RESULTS: Follow-up was between 3 and 13 months (mean, 10 months). All grafts remain clear. The properative mean cylinder was 11.5 diopters and the postoperative mean cylinder was 3.9 diopters. Best corrected visual acuity was improved in 3 eyes. Interface opacification is the main complication, like other forms of epikeratoplasty. Epithelial ingrowth occurred in one eye and the lenticule was replaced. CONCLUSIONS: Epikeratophakia is a simple and effective way for the treatment of severe Terrien's degeneration. This procedure not only increases the corneal thickness, but also hepls the cornea to preserve its transparency, since the Bowman's layer remains intact.

Adult↗