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Biomedical subjects

L Li

Publications and source records attributed to L Li.

At least 1,729 records · Page 96Linked to original sources
PubMed1993

Diffusion and perfusion magnetic resonance imaging studies to evaluate a noncompetitive N-methyl-D-aspartate antagonist and reperfusion in experimental stroke in rats.

BACKGROUND AND PURPOSE: Diffusion magnetic resonance imaging (MRI) can quantitatively detect focal ischemic injury within minutes of onset, and perfusion MRI can evaluate the brain's microcirculation. N-Methyl-D-aspartate (NMDA) antagonists and reperfusion can reduce lesion size in stroke models. We used diffusion and perfusion MRI to evaluate the in vivo effects of a noncompetitive NMDA antagonist, CNS 1102, in a temporary ischemia model. METHODS: Sixteen Sprague-Dawley rats underwent suture occlusion of the middle cerebral artery. Fifteen minutes after occlusion, animals were randomly assigned to treatment with CNS 1102 (n = 10) or placebo (n = 6), receiving a bolus of 1.13 mg/kg at that time and an infusion of 0.785 mg.kg-1.h-1 for the next 165 minutes. The placebo group received a saline bolus and infusion. Diffusion MRI studies by a spin-echo technique were initiated 30 minutes after occlusion and repeated every 30 minutes for the next 3 hours. Perfusion MRI studies were obtained using echo-planar imaging after injection of superparamagnetic iron oxide particles, immediately before and 15 minutes after withdrawal of the occluder at 3 hours after middle cerebral artery occlusion. At 24 hours, the animals were clinically evaluated (scale of 0 to 5) and electively killed, and the brain was stained with triphenyltetrazolium chloride to evaluate infarct size. RESULTS: Diffusion imaging demonstrated markedly reduced ischemic lesion area in the CNS 1102 group during occlusion--10.5 +/- 7.3% (mean +/- SEM) of the ischemic hemisphere (optic chiasm slice) at 30 minutes after occlusion versus 50.0 +/- 2.7% of the hemisphere in controls (P < .02). With reperfusion after 3 hours of temporary ischemia, diffusion imaging documented an additional 29% reduction of the ischemic lesion area in the CNS 1102-treated group (P < .01) compared with the prereperfusion ischemic lesion area, with no change in the placebo group. During occlusion, perfusion imaging demonstrated a relative signal intensity decline of 31.5 +/- 7.7% in controls and 83.4 +/- 7.6% in the CNS 1102 group (P < .005), indicating better perfusion in the latter group. After removal of the occluder, perfusion improved in both groups and was not significantly different. Post mortem infarct volume was 53.8 +/- 20.0 mm3 in the CNS 1102 group and 216.8 +/- 16.1 mm3 in the controls (P < .0001). Clinical outcome at 24 hours was 1.1 +/- 0.4 in the CNS 1102 group and 4.0 +/- 0.5 (scale of 0 to 5) in the controls (P < .005). CONCLUSIONS: This study demonstrates that CNS 1102 reduces early postischemic injury as documented by diffusion MRI and improves perfusion as documented by perfusion MRI and that reperfusion confers additional reduction of ischemic lesion size.

Animals↗
PubMed1993

Effects of a novel NMDA antagonist on experimental stroke rapidly and quantitatively assessed by diffusion-weighted MRI.

We employed diffusion-weighted MRI (DWI) to identify regions of focal brain ischemia during the first 3 hours after permanent occlusion of the middle cerebral artery in rats. Using DWI as early as 30 minutes after the onset of ischemia, it was possible to identify the areas of brain destined to progress to infarction over the next 24 hours in untreated animals, as demonstrated by postmortem evaluation. DWI studies revealed the cerebroprotective effects of a noncompetitive N-methyl-D-aspartate receptor antagonist, CNS 1102, administered 15 minutes postocclusion, both on the cortical and caudoputaminal regions during the initial 3 hours of ischemia. Although the treatment effect lessened over the next 21 hours in a few animals with lower plasma drug levels at 3 hours, postmortem studies demonstrated a 66% reduction in the total volume of infarcted tissue with the treatment and confirmed the DWI results. T2-weighted MRI obtained at similar times revealed little or no abnormality. These results suggest that DWI provides a sensitive in vivo measure of focal cerebral ischemic injury and can assess the beneficial effects of cytoprotective therapy. DWI may be useful in the early evaluation of human stroke patients and in monitoring the effects of cerebroprotective therapies in the clinical setting.

Animals↗
PubMed1993

Muller cell expression of glial fibrillary acidic protein (GFAP) in RPE-cell transplanted retinas of RCS dystrophic rats.

In Royal College of Surgeons (RCS) rats with inherited retinal dystrophy, photoreceptor cell degeneration is accompanied by Muller cell changes, in particular, increased expression of the intermediate filament protein, glial fibrillary acidic protein (GFAP). In this study, we examined the expression of GFAP in retinas of 4 month-old RCS dystrophic rats either transplanted with normal retinal pigment epithelial (RPE) cells or injected with vehicle (sham control). The sham-injected and non-treated retinas showed increased expression of GFAP in Muller cells with advancing age. GFAP-immunostained Muller processes were observed in the region of the subretinal space of these RCS retinas beginning by 4 months. However, in the retinas of RCS rats transplanted with normal RPE cells, GFAP expression by Muller cells was significantly reduced. Specifically, under the transplanted RPE cells, GFAP-immunolabeled Muller radial processes were not observed and GFAP immunostaining was not present in the subretinal space at any time period examined. Immunoblot analysis of the superior hemisphere of RPE-cell transplanted retinas of 4 month-old RCS dystrophic rats showed less GFAP immunostaining than sham-injected and the inferior hemisphere of retinas of age-matched RCS rats. This study showed that in normal RPE-cell transplanted retinas of RCS rats, in addition to rescued photoreceptor cells, there was an accompanying stabilization of Muller cells as demonstrated by a reduction in the expression of GFAP.

Animals↗
PubMed1993

Epidemiological study on poliovirus isolates from patients with acute flaccid paralysis in Shandong province in China.

In five years from 1988 to 1992, 51 polioviruses were isolated from patients with acute flaccid paralysis in Shandong province in China. Of the 51 poliovirus isolates, 17 were type 1, 18 type 2 and 16 type 3. Twelve type 1 viruses isolated during the period from 1988 to 1990 were shown to be wild strains by serology and the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. These wild strains were classified into three groups by PCR-RFLP. The other type 1 isolates were Sabin-like strains. No wild strain was isolated in 1991 or 1992. All isolates of types 2 and 3 during the five years were Sabin-like strains. These data suggest that wild strains of polioviruses will soon be eradicated in Shandong province.

Acute Disease↗
PubMed1993

[The effects of salvia miltiorrhiza, polysaccharide sulphate, dextran 40 and mannitol on the viscoelasticity properties of red blood cell suspension].

In vitro, the effects of Dextran 40(DX40), mannitol, salvia miltiorrhiza and polysaccharide Sulphate (PSS) on the viscoelasticity properties of red cell suspensions were studied. The results demonstrated that when the concentration of the drugs increased, mannitol increased eta 5 x 96, eta 51 x 2, eta', eta" and G', and DX 40 increased the values of eta' eta" and G', but it had no obvious effect on eta 5 x 96 and eta 51 x 2; salvia miltiorrhiza and PSS had no obvious effect on eta 5 x 96, eta 51 x 2, eta', eta'' and G'. However, the average values of eta', eta'' and G' of Salvia miltiorrhiza and PSS groups were lower than those of DX 40 and Mannitol groups. Clinically, these four drugs in treatment doses might improve viscoelasticity properties of whole blood. For treating the ischemic cerebral vascular diseases and hyperviscosity syndromes, Salvia miltiorrhiza and PSS could be infused faster, but DX40 and mannitol should be infused slowly.

Blood Viscosity↗
PubMed1993

Relationship between the characteristics of immunopathological expression of hepatitis C virus antigen and hepatocytic injury.

Biopsied liver tissues from 352 cases were tested for hepatitis C virus (HCVAg) with improved PAP immunohistologic chemical method. Furthermore, corresponding seroantibody to hepatitis C virus was also tested. The total HCVAg positive rate was 9.1%. The HCVAg positive rate in chronic persistent hepatitis (CPH) was 5%. The HCVAg positive rate in chronic active hepatitis (CAH) was 11.2%. The HCVAg positive rate raised gradually along with the severity of hepatocytic injury. HCVAg may be seen in necrotic liver cells exfoliating into the liver sinus, indicating a close relationship between HCVAg and hepatocytic injury. Expression of HCVAg was mostly of the nucleus type in CPH cases and was mostly of the plasma type in CAH cases. The periphery of nucleus type-expressed positive cells generally had no marked inflammatory cell infiltration. The periphery of plasma type-expressed positive cells had a certain amount of inflammatory cell infiltration. Along with the severity of hepatocytic injury, HCVAg expressed itself in a positive correlation according to the nucleus and plasma types. The HCVAg positive cells were located mostly in the lobular peripheral band and rarely located in the venoperipheral band. It was possible that this had some relation with the lobular microcirculation of blood and blood supply. In this study, there was no obvious correlation between the HCVAg positive rate in hepatic tissues and the anti-HCV positive rate in sera. Neither the patients with HCVAg positive liver tissues nor the patients with seropositive anti-HCV had any history of blood transfusion and the use of blood products.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[The role of hemorheologic disturbance in experimental acute pancreatitis].

The role of hemorheologic disturbance in experimental acute pancreatitis was studied in Wistar male rats. It was found that pancreatic duct obstruction with secretin stimulation could induce acute interstitial pancreatitis (AIP), but when high molecular dextran intravenous injection being added, acute necrotizing pancreatitis (ANP) was induced. The authors suggest that the high molecular dextran can increase blood viscosity, aggregation of erythrocytes and decrease erythrocyte deformability, which results in pancreatic microcirculatory disturbances and promotes progressive pancreatic necrosis. Hemorheologic disturbance is one of the key factors in the pathogenesis of ANP.

Acute Disease↗
PubMed1993

[Separation and identification of stimulants and their metabolites].

Forty-one stimulant drugs banned by the International Olympic Committee were studied after they were administered to human volunteers. The parent drugs and their metabolites in free or conjugated forms in human urine collected within 24 hours after administration of the drugs were extracted, separated and identified. The separation was performed on a capillary gas chromatograph with nitrogen-phosphorous detector, while the identification was achieved on a capillary gas chromatograph with mass-selective detector. The extract was injected into the gas chromatograph both directly and after derivatization with trifluoroacetic anhydride (TFAA) or N-methyl-N-trimethylsilyl trifluoroacetamide (MSTFA) as well as TFAA and MSTFA combined. The conjugated metabolites were studied after acid hydrolysis of the extract and then selectively derivatized as above. The results are summarized in 4 tables in the text.

Central Nervous System Stimulants↗
PubMed1993

[Adenosine deaminase activity and isozyme test for differentiation diagnosis of tuberculous pleurisy].

Adenosine deaminase (ADA) activity and isozyme were studied on 78 patients with pleural fluid. ADA activity in pleural fluid was higher in 49 cases of tuberculosis than those in 29 cases of non-tuberculosis (P < 0.01). The ratio of pleural fluid to serum for ADA was greater than 1 in tuberculous pts, whereas less than 1 in non-tuberculosis pts (P < 0.01). ADA isozyme III was higher in tuberculosis than those in non-tuberculosis pts (P < 0.01). It was suggested that these indexes may be useful in differentiating tuberculous pleurisy from non-tuberculous pleurisy.

Adenosine Deaminase↗
PubMed1993

[Effects of dimercaptosuccinic acid per os on copper excretion in rat].

After dimercaptosuccinic acid (DMSA) was given intragastrically by gavage (ig) 0, 250, or 500 mg.kg-1 following in CuSO4 30 mg.kg-1 daily x 3 d in rats, the Cu contents of serum increased markedly within 1-12 h. When ig DMSA daily x 3 d, the excretion of Cu in urine per 24 h in the treated group was greatly promoted vs the control (P < 0.01), that in the 250 or 500 mg.kg-1 group were enhanced 2.4-3.8 and 5.8-7.8 times, respectively. That the excretion of Cu was increased in bile but not in feces suggested the plausible existence an enterohepatic circulation.

Animals↗
PubMed1993

[Effects of osthole on the isolated guinea-pig ileum and taeniae coli].

Effects of osthole (Ost) and verapamil (Ver) were investigated in the isolated guinea-pig ileum and taeniae coli. In the isolated guinea-pig ileum or taeniae coli, Ost and Ver were both found to inhibit the contractions induced by acetylcholine (ACh), histamine (His) and KCl in a dose-dependent manner; and noncompetitively antagonize the CaCl2 cumulative dose-response curves, with pD2 values of 4.41 +/- 0.15 and 7.0 +/- 0.2, respectively. Ost at dose of 100 mumol/L and Ver at 1 mumol/L inhibited CaCl2 0.2 mmol/L induced the contractions of the isolated guinea-pig taeniae coli, and the contractions can be abolished by adding CaCl2 2 mmol/L in Ca(2+)-free medium; both of them showed pronounced inhibitions on intracellular calcium-dependent contractions induced by ACh, but showing no effects on the extracellular calcium-dependent contractions. These results indicate that Ost has calcium antagonistic effect and is similar to Ver in mechanism.

Acetylcholine↗
PubMed1993

Cloning of coat protein gene of soybean mosaic virus and its expression in Escherichia coli.

The 3'-terminal genomic region of the Beijing isolate of soybean mosaic virus (SMV-BJ) has been cloned through technique of polymerase chain reaction (PCR). We have analyzed the nucleotide sequence of 3' region of SMV-BJ genome. Comparisons of the nucleotide and deduced amino acid sequence of SMV-BJ coat protein gene with those of SMV-N strain show 93.4% and 98.5% identity between them, respectively. Alignments of the 3' non-coding sequence in pairs with that of SMV-N strain show homology of 88.8%. It has been found that the SMV coat protein gene is expressed in E. coli by western blot analysis. The coat protein produced in E. coli has the same electrophoretic mobility as the authentic coat protein.

Amino Acid Sequence↗
PubMed1993

Insect tolerance of transgenic Populus nigra plants transformed with Bacillus thuringiensis toxin gene.

Leaves and stem segments of Populus nigra were transformed with A. tumefaciens LBA4404 harboring a binary vector containing chimeric genes of NPT and 35S-omega-B.t. toxin-Nos. Nineteen regenerated kanamycin resistant plants were analyzed by DNA hybridization, out of which 10 were shown to be the candidates of transgenic plants. Insect tolerance tests showed that the transgenic plants were toxic to two lepidopteran pests, Lymantria dispar L. and Apocheimia cinerarius Erschoff. Based on the results of Southern blot of PCR products and the cluster analysis of their growth and insect resistance, three independent transgenic plants were selected, which were then propagated in the nursery field. This field test is currently in progress.

Agrobacterium tumefaciens↗
PubMed1993

[Observation on the phenomenon of propagated sensation along meridians in youngsters].

That the opinion on the relation between the propagated sensation along meridians (PSM) and the age of the subjects was divergent in the results reported by some authors. In the last 10 years, we have performed a systematic investigation on PSM on a group of 536 youngsters. The main characteristics of PSM in youngsters were just the same as that of adults. However, the incidence of PSM in youngsters, particularly the degree of distinctness of PSM, was by far higher than that of adults. The results were stable and could be repeated in the experiments performed in different years. It showed that there was surely a close relation between the degree of distinctness of PSM and the age of subjects. This fact can not be appropriately explained at present. However, it provides an important clue to clarify the factors which influence the appearance of PSM, and in turn to promote the improvement of the therapeutic effect of acupuncture and cilacriation of the mechanism underlying the formation of PSM.

Acupuncture Therapy↗
PubMed1993

[Expression of cyclin B in megakaryocytes and cells of other hematopoietic lines].

Megakaryocytes are normal bone marrow cells which have the unique ability to become polyploid. This phenomenon is termed endomitosis and its mechanism remains poorly understood at present. It is known that the cell cycle of eukaryotes, particularly at G2/M transition, is regulated by a complex with histone H1 kinase activity, the maturation- or M-phase promoting factor (MPF). We have therefore studied the expression of subunits of MPF, the p34cdc2 and cyclin B in normal bone marrow culture megakaryocytic cells, blood leukocytes and platelets as well as in human megakaryoblastic cell lines Dami, Meg-01, HEL and the promyelocytic cell line HL60. Using immunohistochemistry and electron microscopy we have observed that cyclin B was virtually undetectable in megakaryocytes and platelets, but was abundant in granulocytes, monocytes/macrophages and HL60. Studies by RT-PCR showed the presence in large quantities of mRNA of cyclin B in all cell types studied, even in megakaryocytic-like cells. These observations suggest some important implications in the understanding of the mechanisms of megakaryocyte polyploidization and related endomitosis.

Blood Platelets↗
PubMed1993

[An epidemiological survey of hydatidosis among 27,051 persons in Shihezi district].

An epidemiological survey of hydatidosis was carried out among 27,051 persons in Shihezi District, 784 were found to be positive cases and the total standardized infection rate of hydatidosis was 2.84%. Among all farms, the infection rates in the No. 133, No. 152 and No. 135 farms were the highest. The infection rates among various nationalities were 6.69% (Kazak), 4.04% (Uygur), 3.42% (Hui), 2.39% (Han). There was a significant difference between males (2.35%) and females (3.33%) (P < 0.01). The young children were the majority (56.02%) among the positive cases. This investigation was carried out from about 1/20 of the total population (532,157 persons) and showed the infective state of hydatidosis in Shihezi District basically. The method of blood spot-ELISA on filter paper which was used instead of serum-ELISA simplified the procedure and cut down expenses, being particularly suitable for a large-scale investigation.

Adolescent↗