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Biomedical subjects

S Li

Publications and source records attributed to S Li.

At least 1,513 records · Page 84Linked to original sources
PubMed1993

Mutual synaptic associations between neurons containing neuropeptide Y and neurons containing enkephalin in the arcuate nucleus of the rat hypothalamus.

We determined reciprocal synaptic associations between neurons containing neuropeptide Y (NPY) and neurons containing enkephalin-8 peptide (Enk-8) in the arcuate nucleus (ARC) of the rat hypothalamus by using a double-staining immunocytochemical method. Animals treated with an intraventricular administration of colchicine and animals treated with a hemicomplete cut of the medial basal hypothalamus were used. We principally labeled NPY with silver-gold particles and Enk-8 with diaminobenzidine (DAB) chromogen but in part labeled reversely the two antigens to obtain better visualization of Enk-8 cell bodies. Neurons immunoreactive for NPY were found in the mediobasal area, while those for Enk-8 were located somewhat laterally. Their fibers, however, were densely distributed throughout the ARC in a similar fashion. Electron microscopically, we found synaptic junctions between axonal terminals of Enk-8 neurons and perikarya of NPY neurons and between axonal terminals of NPY neurons and perikarya of Enk-8 neurons. In addition, we found synaptic junctions between immunoreactive Enk-8 cell bodies and processes and also between immunoreactive NPY cell bodies and processes. These interneuronal associations may contribute to the interaction of information coming in or going out from this nucleus.

Animals↗
PubMed1993

Chronic administration of muscimol and pentobarbital decreases gonadotropin-releasing hormone mRNA levels in the male rat hypothalamus determined by quantitative in situ hybridization.

The role of GABA in the control of gonadotropin-releasing hormone (GnRH) secretion is still controversial. In order to investigate the role of the GABAergic system in the regulation of GnRH gene expression in the rat brain, we studied the effects of chronic administration (2 days) of the GABAA receptor agonist muscimol and the central-type barbiturate receptor agonist pentobarbital on GnRH mRNA levels measured by in situ hybridization. Treatment with pentobarbital produced a 24% decrease in the hybridization signal. Similarly, muscimol treatment decreased the signal by 28%. The concomitant administration of the two GABAA receptor agonists resulted in a decrease (37%) of mRNA levels which was significantly more marked than that induced by pentobarbital or muscimol alone. The present results, together with previous data, indicate that the administration of pentobarbital or muscimol can inhibit not only the release of GnRH but also the gene expression of the neuropeptide as evaluated by mRNA level measurements.

Animals↗
PubMed1993

Binding of 111In-labeled LDL to platelets of normolipemic volunteers and patients with heterozygous familial hypercholesterolemia.

Low density lipoproteins (LDLs) were isolated by ultracentrifugation and radiolabeled with 111In. The in vitro binding of these radiolabels onto platelets of normolipemic volunteers (n = 15) and patients (n = 36) with heterozygous familial hypercholesterolemia (FH) was investigated. Binding was saturable and indicated high-affinity binding sites capable of binding 1,757 +/- 289 ng protein of 111In-LDL per 10(9) platelets (dissociation constant [Kd], 6 +/- 3 micrograms protein/mL) in healthy volunteers and significantly (p < 0.001) lower amounts in the FH patients (mean, 633 +/- 341 ng protein/10(9) platelets; Kd, 10 +/- 5 micrograms protein/mL). The capacity of native LDL to displace bound 111In-LDL by half amounted to 10 +/- 4 micrograms protein/mL in volunteers and 22 +/- 8 micrograms protein/mL in FH patients (p < 0.001). Treatment with gemfibrozil alone or in combination with cholestyramine in 10 patients resulted in increased 111In-LDL binding by platelets (470 +/- 307 [mean +/- SD] ng protein/10(9) platelets before therapy, 948 +/- 650 ng protein/10(9) platelets after 2 months of therapy [p < 0.01], and 1,272 +/- 701 ng protein/10(9) platelets after 6 months of therapy [p < 0.01]). Significant correlations between 111In-LDL binding capacity and apolipoprotein B (r = -0.83, p < 0.001) and LDL cholesterol (r = -0.80, p < 0.000) concentrations were found. Patients with clinically manifested atherosclerosis (p < 0.01) and those with diabetes mellitus (p < 0.05) had significantly lower platelet LDL binding sites. The findings demonstrate 111In-lipoprotein-specific binding sites on human platelets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Relations between opacification of lens protein and pH].

Some of the acidic reagents or medicines (i.e. HCl, GSH & GSSG, Vit. C, Vit. B6) and basic reagents (Tris) were used to regulate the pH of water soluble protein and urea soluble protein solution of human lenses. At a certain pH, the lens protein solution appears opalescence, the pH of opacity solution which is measured by pH meter is around 5.6-6.3. The opalescence of water soluble and urea soluble lens protein solution of human fetal, adult and cataractous lenses were also determined by gradient acidic and basic solution. The result show that the opacity is more obvious in soluble protein solution of cataractous lenses and clear lenses than in that of fetal lenses, and the lens urea soluble protein has a marked opalescence in comparison with the water soluble protein. So we assume that cataractogenesis might be associated with the change of pH within lens.

Adult↗
PubMed1993

[The 43KD polypeptide in the proteins of human lens].

The total proteins, water--soluble proteins and the urea--soluble proteins of the lens from fetal, adult and senile cataract were determined by SDS--PAGE. It was found that there was a 43KD polypeptide in the capsular--epithelium of all lens stated above. The band on SDS-PAGE corresponding to 43KD polypeptide was wide in the water--soluble proteins of the cortex and nucleus of the lenses obtained from over 14-year-old individuals. It became blurred in the urea--soluble proteins of cortex and nucleus of lens with aging, whereas it became almost disappeared in the senile cataract lens.

Adolescent↗
PubMed1993

[Malonaldehyde, superoxide dismutase and human cataract].

UV-spectrophotometry and fluorometry were used to study Malonaldehyde (MDA) and Superoxide Dismutase (SOD) in normal, cataractous human lenses and red blood cells of the patients with cataract. MDA content of senile and complicated cataractous lenses was significantly higher than that of normal human lenses, while that of complicated cataract was significantly higher than that of senile cataract. SOD activity of senile and complicated cataractous lenses was significantly lower than that of normal human lenses, while there was no marked difference between senile and complicated cataractous lenses. Significant correlation between cataractous lenses and red blood cells was not found in MDA content and SOD activity. There was a negative correlation between SOD and MDA in normal human lenses, but no correlation between SOD and MDA in cataractous lenses. The study shows that lipid peroxidation may be one of the possible mechanisms of cataractogenesis in human, and emphasizes the role of SOD in prevention of photoperoxidative damages to the tissues.

Adult↗
PubMed1993

[Amino acid analysis of retinal S-antigen and interphotoreceptor retinoid-binding protein].

Retinal S-antigen and interphotoreceptor retinoid-binding protein (IRBP) were purified by DEAE-Sephacel ionexchange chromatography and Con A Sepharose affinity chromatography. Amino acid analysis of the S-antigen and IRBP was carried out and compared with that presented by others. The possible reason for difference with regard to some amino acids and related problems were analyzed and discussed.

Amino Acids↗
PubMed1993

[Clinical and pathological analysis on 44 cases of lid haemangioma].

Forty four cases of lid haemangioma are reported. 6 cases were diagnosed as cavernous haemangioma and treated by sclerosis therapy. The postoperative pathology examination to the other 38 cases showed that there were 9 cases of capillary haemangioma, 18 cases of cavernous, 8 cases of benign haemangioendothelioma, 1 case of racemose and 2 cases of mixed type. The age of these patients ranged from 2 months to 60 years and the disease history from 6 days to 26 years. From the clinical and pathological aspects the angioma is briefly discussed. The result suggest that the recurrence of the tumor may be associated with enlarged and deformed nutritious vessels. We advocate that the operation should be performed as early as possible.

Adolescent↗
PubMed1993

[Effect of targeting treatment of mitomycin C immunoconjugate on stomach neoplasm].

An anti-gastric cancer monoclonal antibody MGb2-mitomycin C conjugate via dextran T-70 as intermediate (MGb2-PAD-MMC) was produced, and 28-30 g molecules of MMC were introduced into 1 g molecule of MGb2. Ninety-six hours after ip of 125I-MGb2-PAD-MMC (1.48 MBq/22 micrograms MGb2 per mouse) to nude mice bearing human gastric cancer SGC-7901, the tumor tissue:blood (T/NT) radioactivity ratio was 2.6, very much higher than that of the control 125I-normal IgG-PAD-MMC group (T/NT = 0.20). Single photo computed tomography imaging confirmed the results of biodistribution study. MGb2-PAD-MMC exhibited selective killing action on the SGC-7901 cells in vitro, which was considered to be mediated by monoclonal antibody MGb2. Nude mice inoculated with SGC-7901 xenograft in bilateral subrenal capsule were treated by MMC (ip), human recombinant interferon-alpha (Hu-IFN-alpha im), MGb2-PAD-MMC (ip) and MGb2-PAD-MMC+Hu-IFN-alpha daily for 5 d beginning 4 h after inoculation. The efficacy of the reagents estimated by the reduction of tumor size and calculated by T/C (%), was 28.3%, 16.4%, 47.8%, and 83.1%, respectively. These results demonstrated that the antitumor effect of MGb2-PAD-MMC was superior to free MMC, and that the Hu-IFN-alpha might further enhance the action of MGb2-PAD-MMC.

Adenocarcinoma↗
PubMed1993

In vitro oocyte maturation in the zebra fish, Brachydanio rerio, and the fertilization and development of the mature egg.

The in vitro maturation process of zebra fish oocytes was investigated. When incubated with medium EM-199 containing 0.5 microgram/ml of 17 alpha-hydroxyprogesterone in an incubator with 80% O, 25 degrees C, the germinal vesicles of the oocytes in stage IV migrated from middle between the center and the periphery to the periphery in 40 min, and the oocytes went into stage V 30 min later, undergoing germinal vesicle breakdown (GVBD) with a GVBD% of 59%. Two hours were needed for such oocytes to complete their final maturation. The mature eggs cannot come off the follicle layer surrounding them naturally (ovulation). By removing the follicle and adding active sperm for insemination, we can cause the mature eggs to become fertilized. The chorion elevated and blastoderm formed on the animal pole. The cleavage and development of the fertilized eggs followed are the same as naturally matured fertilized eggs. Using blastula as the criterion for a successful fertilization of the in vitro maturated egg, the fertilization rate is 78%. This is the first report on the successful oocyte final maturation in vitro in zebra fish. The establishment of an oocyte in vitro maturation technique has given grounds for the further investigation on the transfer of foreign genes in the germinal vesicles of the oocytes.

17-alpha-Hydroxyprogesterone↗
PubMed1993

[TS-d as an adjuvant for cancer radiotherapy].

TS-d is a rough polysaccharide obtained from polyporaceae JB-2, 615, Kunming mice and rabbit and S180, MA737 tumors were used to study the effects of TS-d. Preliminary results indicated that TS-d is an effective radioprotective and antineoplastic drug with low toxicity and few side effects. When TS-d was injected i.p. to mice at a dosage of 400 mg/kg 60 min before 8.5Gy gamma-irradiation, the survival rate of mice was increased by 43% (P < 0.05) as compared with control. When 400 mg/kg of TS-d was injected i.p. into mice 60 min before 7.0 Gy gamma-irradiation, the number of WBC, BMC, and CFU-S were significantly increased (P < 0.01-0.001) as compared with control. The inhibitory rates of TS-d on S180 and MA737 were 46%-77% (P < 0.05 and P < 0.001) and 37%-46% (P < 0.05 and P < 0.05), respectively. TS-d showed significant protective effects on the hematopoietic tissues of rabbits exposed to-gamma-irradiation. The LD50(7d) values of TS-d given i.p. in Kunming mice were 4027.6 +/- 434.9 in male and 5115.6 +/- 453.5 mg/kg in female, and the LD50(7d) values of TS-d given i.v. in JB-2 mice were 1389.6 +/- 240.8 and 1361.5 +/- 208.3 mg/kg, respectively. TS-d had no effect on the growth of mice at the age of four weeks. TS-d had no effect on the production rate of micronucleus.

Animals↗
PubMed1993

Application of Steffee operation in spinal surgery.

Steffee operation is a surgical method of internal fixation for unstable conditions of the spine. Up to March 1991, 32 cases of various spine disorders were treated with the Steffee system in our hospital. These operations brought good results, as 83.4% of the cases received either good or excellent functional and clinical ratings postoperatively. Among patients with spondylolisthesis, the degree of slip correction averaged 58.5% postoperatively. Neurological complications are avoided by accurate localization of the screws.

Adult↗
PubMed1993

[Heterogeneity of the immunoreactivity of A14, A19, B16 and B26- (125I) monoiodoinsulin to different species of anti-insulin immuno sera].

By using lactoperoxidase oxidation with 6 mol. urea in the reaction medium, the four tyrosine residues contained in insulin molecule were iodinated as monoiodoinsulins. These tracers, namely A14, A19, B16 and B26- (125I) monoiodoinsulins were separated with polyacrylamide gel electrophoresis+QAE-Sephadex A25 chromatography. The present study demonstrated that the radiochemical purity of these tracers was high (> 98%) and the specific radioactivity also high. The binding of these tracers to surplus insulin antibody was more than 95%. These our tracers were tested in two RIA systems against 35 species of guinea-pig anti-insulin immuno sera to compare their immunoreactivity (Ka, Scatchard analysis) to each immunoserum. The two RIA systems were antibody dilution and self displacement, and in both of them, only iodinated insulin and insulin antibody were present in the reaction fluid. The results showed that for 16 antiinsulin immuno sera, Ka for A14, A19, B16 or B26-monoiodoinsulin were significantly different, and for the rest 19 immuno sera no significant difference could be detected. The possible mechanism and implication of this phenomenon were discussed.

Animals↗
PubMed1993

Sequence analysis of the colonization factor antigen 1 gene of ETEC and observation of CFA/1 recombinant clone with electron microscopy.

The structure gene of the colonization factor antigen 1 (CFA/1) has been sequenced. The amino acid sequence of CFA/1 precursor deduced from the nucleotide sequence is composed of 170 amino acids. The first 23 amino acids are considered to be the signal peptide of the CFA/1 protein. On the basis of the nucleotide sequence, three amino acids are different from the protein sequence. Amino acid residues at positions 37, 76 and 97 are found to be Ala, Asp and Ser, instead of Val, Asn and Ala as determined by amino acid sequencing. The CFA/1 is very hydrophobic amino acids. Among the total 170 amino acids, 47% of them are hydrophobic amino acids. CFA/1 gene has a typical Shine-Dalgarno sequence and-10 sequence, but no 35 promoter sequence could be found. The G + C ratio of CFA/1 gene is 40%. Observation of negatively stained preparations of the culture with electron microscopy showed that no fimbriae were found on E. coli C600 strain itself, but the cell carrying the plasmid showed thick pili on its surface.

Amino Acid Sequence↗
PubMed1993

Carbamylation of human lens gamma-crystallins: relevance to cataract formation.

Cigarette smoking is a main source of cyanide in human body, which can be taken as a risk factor of cataract formation. In this study, combined gas chromatography and mass spectrum (GC/MS) was used to determine the amino acid hydantoin after the incubation of soluble human lens gamma-crystallins with cyanate. The carbamylated amino acids obtained by this procedure are alanine and glycine, which are N-terminal amino acids of gamma-crystallin, and leucine. The aggregate, which can be observed in carbamylated gamma 1-crystallin on SDS-PAGE, may be related to the formation of disulfide and non-disulfide covalent bonds, and it seems that gamma 2 and gamma 3-crystallins can not be aggregated to any great extend. The results in this study indicate that the GC/MS is an effective method for analyzing the carbamylation of lens proteins; gamma-crystallin may play a very important role in the formation of cataract associated with accumulation of cyanate in human body, such as heavy smoking.

Cataract↗
PubMed1993

[Effects of air pollution on health of residents in vicinity of an electrometallurgical factory in Chengdu].

Air pollution in an electrometallurgical plant in Chengdu was monitored in 1988. Results showed that atmospheric TSP and Ni concentrations in the vicinity of the plant were higher than those in control area; and TSP content higher than its health standard level. A population of 262 children was physically examined in the same pollution and control areas in May, 1988. Physical examinations were as follows:otorhinolaryngological examination, skin patch test of Ni and Co, immune function test (including PHA skin test, salivary LZM content), Ni levels in human hair and urine etc. We found that body burdens of Ni in population of pollution area increased because of the pollution of Ni compounds in the atmosphere. Hair Ni content in pollution area was significantly higher than that in control area, and the positive rate of Ni skin patch test was also markedly higher than that in control area. Case history indicated that there was a significant difference in Ni content as detected by otorhinolaryngological examinations between the pollution and control areas. Some measures were suggested to improve the air quality based on the study.

Adolescent↗
PubMed1993

Development of PVEP in infants and children.

The development of components of VEP was studied in 150 infants and children between 2 weeks and 9 years of age participated as subjects. Ten adult subjects, 25 to 35 years of age were also studied. The results indicated that the VEP had a simple wave form, consisting of only a slowly rising positive wave to 140', 70' and 35' checks from infants of 2 to 8 weeks following birth. P1 wave appeared in response to 17.5' check stimulus at 10 weeks following birth. The latencies of P1 components shortened dramatically from infants of 2 to 4 months and the latencies of low spatial frequencies (140' and 70' checks) from infants at 4 months of age reached adult level but P1 latency of medium spatial frequency (35' check) did not reach adult level until age of 4 years. The latency of P1 component of high spatial frequency was matured by the end of 9 years of age. The development of P1 waves from both eyes was parallel in normal infants and children. The amplitudes N1P1 and P1N2 from infants and children with 2 months to 9 years were not affected by the age and significantly higher than those of adults group by 2 to 3 factors. Based on the results of our research, three phases were found in the development of the visual function in infants and children. The first phase was up to 4 months after birth, and characterized by the maturation of the low spatial frequencies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗