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Biomedical subjects

L Li

Publications and source records attributed to L Li.

At least 1,657 records · Page 92Linked to original sources
PubMed1994

[Chronological characteristics of retinoic acid-induced HL-60 cell differentiation].

HL-60 cells can be induced to differentiate into mature granulocytic cells in a continuous exposure to all-trans retinoic acid (RA) for at least 96 h. In this study, RA was removed after being exposed to HL-60 cells for 12-96h. Then the cells were reincubated in a fresh medium without drug for additional 48-144h and their differentiation markers such as NBT reduction, morphological changes and cytokinetic characteristics were studied. The results demonstrated that once exposed continuously to 1.0 mumol/L RA for at least 48h, the HL-60 cells would proceed to terminal differentiation: about 60-90 percent of the cells became NBT positive, 40-80 percent of cells exhibited decreased nucleus/cytoplasm ratio and marked reduction in the number of nucleoli and displayed matured granulocytic morphology. Cytokinetic studies demonstrated 48-85 percent of cells arrested in G1 phase, which is typical for differentiated cells. However, if the cells were exposed to RA for less than 48h, they would not show differentiation phenotype. These results indicate that 48h exposure is critical for HL-60 cell differentiation induced by RA, and the cell differentiation induced by RA is irreversible and RA-independent.

Cell Differentiation↗
PubMed1994

[Preliminary investigation on acute flaccid paralysis (AFP) cases in Jinan area].

Eighty AFP cases under 12 years old from 6 hospitals in Jinan were investigated. Among them, there were 17 (21.25%) cases with poliomyelitis (POLIO), 40 (50.00%) cases with Guillian-Barre syndrome (GBS) and 23 (28.75%) cases with other AFP diseases. Most AFP cases occurred from May to October and no significant seasonal difference was found for each kind of AFP cases (P > 0.05), but the average age for POLIO cases (1.55 +/- 1.24) was significantly lower than that for non-POLIO AFP cases (3.76 +/- 2.58) (P < 0.01). The reporting rate from hospitals to each level of epidemic prevention station (EPS) for POLIO, GBS and other AFP cases were 100%, 12.50% and 43.75%, respectively (P < 0.01). Sixty-five AFP cases occurred in 6 prefectures around Jinan city. The average incidence rate (per 100,000) for total AFP, non-POLIO AFP and GBS cases among children under 12 years old were 1.11, 0.89 and 0.53, respectively. The results are helpful to estimate the incidence of AFP cases among children in north provinces of China and also indicate that the POLIO surveillance system in Shandong Province at the present is not sensitive enough, so the AFP cases reporting work of hospitals and the surveillance at each level of EPS should be enhanced.

Child↗
PubMed1994

[Quantitative study on the osteogenic potential of vascularized iliac periosteal].

The effect of pedical blood supply, recipient environment, blood supply to the osteogenic capacity of iliac periosteal was investigated. An iliac periosteal flap based on the circumflexa femoris lateralis vessels was developed in a canine model. The vascularied iliac periosteal was rotated onto the quadriceps femoris musculus or epigastrica inferior fibrous-connective tissues in one side and the free flap was done in the same way in another side. 2, 2, 4, 6 animals were killed at 2, 4, 8, 12 week after operation and the flaps were studied by new bone Ca, P content, bone dense measure, double tetracycline labeling, bone histomorphometry analysis and light microscopy. The following results were obtained: (1) Iliac periosteal has good osteogenic capacity; (2) The early good blood supply is much more important than the recipient environment blood supply, it make the bone formation speed 2-4 weeks forward.

Animals↗
PubMed1994

[Pulsed-field gel electrophoresis for the epidemiological analysis of yeast isolates].

Up to now, pulsed field gel electrophoresis (PFGE) has been used successfully for the analysis of the chains of infection of multiresistant staphylococci, enterococci and other germs involved in hospitalism. The purpose of this study was to find out whether yeast isolates from mothers and those from their newborns differed in genotypes. In this investigation, 103 parturient mothers and their children were examined for colonization by yeasts in sampling the vaginal secret at delivery and by taking swabs from the oral mucosa and the anus of the children on the third day after parturition. The samples were cultured on Sabouraud glucose agar and incubated for 48 hrs at 37 degrees C. The differentiation of the isolates was done biochemically by means of the VITEK-AMS system and morphologically on rice-extract agar. Subsequently DNA-fingerprinting analysis was carried out. In 6 cases we could prove the presence of Candida spp. in the mothers as well as in their children. In all cases the strains from mother and child showed the same banding pattern. Likewise, the strains isolated out of the vaginal secretion and the vaginal epithelium of individual women were identical. The differences observed between strains isolated from various women were of low or medium degree. This shows the PFGE to be an efficient procedure to demonstrate the relation of strains derived from mothers and their newborns.

Anal Canal↗
PubMed1994

Poliomyelitis surveillance in Shandong Province, China, 1990-92.

In Shandong Province, China, programmes were initiated in 1991 for mass immunization against poliomyelitis and for the immediate reporting of acute flaccid paralysis (AFP). The incidence of non-poliomyelitis AFP was found to be 0.46-0.61 cases per 100,000 children per annum. It appeared that illness resembling the Guillain-Barré syndrome was underreported. The incidence of such illness peaked among children aged 2-3 years. Although laboratory investigations have improved, in 1992 they were still inadequate in nearly a third of confirmed poliomyelitis cases. As the prevalence of wild poliovirus declines in China, reliable laboratory support needs to be established and adequately sensitive and specific AFP surveillance be developed if poliomyelitis is to be eradicated.

Adolescent↗
PubMed1994

Comparative observation on effect of electric acupuncture of neiguan (P 6) at chen time versus xu time on left ventricular function in patients with coronary heart disease.

Paired experimental design was adopted in this experiment for comparative observation on effect of electric acupuncture (EA) of Neiguan (P 6) at Chen Time (7 a.m. to 9 a.m.) versus Xu Time (7 p.m. to 9 p.m.) on left ventricular function in patients with coronary heart disease (CHD). The results show that EA performed at Chen Time could improve the left ventricular function of CHD patients as indicated by shortening of PEPI and decrease of PEPI/LVETI ratio; on the contrary, EA performed at Xu Time prolonged PEPI and raised PEPI/LVETI ratio in CHD patients, suggesting impairment of left ventricular function.

Acupuncture Points↗
PubMed1994

[Electrophysiological investigation on decussate communication of bulbospinal inspiratory neurons with phrenic nucleus at level of spinal cord].

The experiments were carried out on anesthetized, vagotomized, immobilized and artificially ventilated cats, rabbits and rats. The rhythmic respiratory activities on both sides of the phrenic nerves existed after a hemisection between the 2nd and 3rd cervical cord, while the activities of the phrenic nerve ipsilateral to the hemisection disappeared following a subsequent mid-sagittal section from the 3rd to 5th cervical cord. The amplitude of the phrenic activities on either side was lowered, more remarkably on the ipsilateral side, by the hemisection. These results indicate that there exists a decussate communication of the bulbospinal inspiratory neurons with the phrenic nucleus at the level of spinal cord. In other words, the phrenic nucleus receives inspiratory drives via descending pathways on both sides of the cervical cord, mainly on the ipsilateral side.

Animals↗
PubMed1994

[Induction of apoptosis by harringtonine and homoharringtonine in HL-60 cells].

Harringtonine (HT) and homoharringtonine (HHT) are two alkaloids isolated from the bark of the evergreen tree Cephalotaxus hainanensis Li in the 1970s. They were found to have activity against murine leukemia, Lewis lung carcinoma and B16 melanoma, and used as anti-leukemia drugs clinically. Apoptosis is an active process of programmed cell suicide and now is believed to be an important target for tumor chemotherapy. In this report, the apoptosis inducing effect of HT and HHT in HL-60 cells were observed. The experiments demonstrated that 2 x 10(-7) mol.L-1 of HT and 10(-7) mol.L-1 of HHT could induce apoptosis in HL-60 cells when the cells were exposed to HT and HHT for 4 h. In agarose gel electrophoresis, DNA extracted from HL-60 cells treated with HT and HHT showed a typical internucleosomal DNA degradation, i.e., DNA ladder and parallel morphological changes as nuclear chromosome segmentation and condensation as well as cytoplasma vacuolation. This effect of HT and HHT was shown to appear in a concentration- and time-dependent manner. The efficacy of HT and HHT in inducing apoptosis of HL-60 cells was found to parallel with their cytotoxic activity in HL-60 cells. These results suggest that the mechanism of antitumor action of HT and HHT is related to their apoptosis inducing activity.

Antineoplastic Agents, Phytogenic↗
PubMed1994

[G-banded chromosomes of peripheral blood from both trophoblastic tumor patients and their husbands].

The G-banded chromosomes of peripheral blood from 55 patients with clinically and/or pathologically diagnosed trophoblastic tumors, husbands of 45 patients with the disease and 181 female and male normal controls were analyzed. Loss of chromosome 22, sporadic translocation of chromosome 7; 14 and low percentage mosaicism of sex chromosomes were noted. Significantly increased frequencies of the latter two abnormalities as well as another one, pericentric inversion of chromosome 9, were detected in both the patient and the husband groups, suggesting that these chromosome abnormalities might be causal factors of trophoblastic tumors.

Chromosome Deletion↗
PubMed1994

[Restriction digestion of two kind of baculoviruses and the location of their p10 genes].

The length of SeNPV and LsNPV genomes DNA were calculated to be 133kb and 164kb respectively, according to digestion with 5-8 restriction endonuleases. In order to map p10 gene in Baculoviruses DNA by pure probe, two probe vectors, pAcHP106 and pAcEP102, were constructed with 3'-0. 18kb and 3'-0. 18kb + 5'-0.24kb (coding sequence and promoter) from AcNPV p10 gene. The p10 genes of both baculoviruses, SeNPV and LsNPV, are located with 0.18kb and 0.42kb probes produced by random primer labeling.

Amino Acid Sequence↗
PubMed1994

[Detection of methicillin-resistant Staphylococcus aureus using PCR and non-radioactive DNA probes: III. Mutations of the fem A gene in clinical strains of Staphylococcus aureus].

Methicillin resistance in S. aureus is primarily due to the presence of the mec A gene. However, in addition to mec, the phenotypic expression of methicillin resistance requires the presence of an additional gene(s), fem A which is chromosomally encoded. Previous studies suggest an increase in the biochemical function of fem A gene products due to base substitutions in the region upstream of the fem A gene and in its coding frame. The partial nucleotide sequences of fem A regions in reference and clinical strains of S.aureus were therefore analyzed by PCR-direct solid-phase sequencing and suitable DNA probes. Amplified target DNAs of 251, 330 and 271 bp were resolved on ethidium bromide-stained gels and hybridized with DNA probes conjugated to alkaline phosphatase. In ATCC 12600 strain, a palindromic sequence was conserved in the region upstream of fem A. However, it was destroyed by the occurrence of mutations in other reference, and clinical strains tested regardless of whether they are methicillin-susceptible or resistant. Furthermore, in the coding frame of fem A, two missense mutations were present in MSSA and MRSA without any regularity. These findings suggest that mutations in the fem A region may not be a single factor essential for regulation of methicillin resistance, although fem A probably functions cooperatively with mec A.

Base Sequence↗
PubMed1994

[The diagnostic value of the assay of lactate dehydrogenese combined with other tumor markers in ovarian cancer].

Thirty-five cases of ovarian cancer, 35 ovarian benign tumors, 31 other gynecologic cancer and 35 normal controls were assayed for LDH, LDH-isoenzyme, SA, CEA, beta 2-MG and AKP. The results showed: (1) The average content of tumor markers in ovarian cancer was higher than benign tumor and healthy controls. (2) The positive rate of tumor markers in stage I and II patients of ovarian cancer was lower than in stage III and IV. (3) In the tumor markers, the diagnostic value of LDH-isoenzyme for ovarian cancer was best. (4) Combined assaying LDH, LDH-isoenzyme and SA was superior to using one marker for the diagnosis of ovarian cancer.

Adolescent↗
PubMed1994

[Descriptions of three new species of the genus Delia, anthomyiidae, diptera in Sichuan, China].

Three new species of the genus Delia distributed in Mountain Emei and Huanglong Canyon have been identified and kept in our Parasitological Laboratory. 1. Delia taonura sp. nov. (Fig 1-3) male: Having no blunt bristles on the 5th sternite and long hairs on posterior part of the cercal plate, the new species is superficially similar to Delia longcauda (Strobl), but its round cercal plate and wider surstyle are different from those of the latter. Holotype male, Huanglong canyon, July 17, 1991, Coll. Deng Axiao. 2. Delia stenostyla sp. nov. (Fig 4-6) male: The new species is related to Delia nemostylata Deng, 1983, but its surstylus with an apical part expanding and curving forwards gradually, ependrium with short and straight hairs standing on the ventral side are different from those of the latter. Holotype male, Mountain Emei, Paratypes 224 male male, Minshan region, June, July 1982-1992, Coll. Deng Anxiao and Li Ling. 3. Delia conjugata sp. nov. (Fig 7-9) male: It is related to No. 2 mentioned above. The present species is different from No. 2 as follows: the surstyli with straightening on anterior border in proximate two thirds and expanding in distal one third, and the abdomen cylindrical. Holotype male, Paratypes 14 male male, Mountain Emei, July 1984, Coll. Deng Anxiao.

Animals↗
PubMed1994

[Synaptonemal complex analysis of 13/17 Robertsonian translocation in the domestic pig].

G and C-banding study of the chromosomes of several male pigs, indicate that all of these pigs carry rob(13;17). The karyotype is 2n = 37, XY, rob (13;17). In this paper, silverstained Synaptonemal Complexes (SCs) in surface-spread pachytene nuclei from these pigs are analysed by electron microscope. The result is as follows: Robertsonian translocation metacentrics rob (13;17) paired with homologous acrocentrics (13,17), forming a trivalent. All trivalents are in a cis configuration and there is delayed pairing in the trivalent. We measured every part of trivalent in the different stage of prophase (based on the morphology of XY-bivalent). It is shown that accompanying with rob(13;17) formation there has been a deletion in the proximal part of 13, 17 translocation chromosome. In the process of synapsis, the length adjustment phenomenon in the trivalent occurred: a. There is nonhomologous synapsis between the two short arms of the acrocentrics (13;17). The length of short SC varied. b. The position of the short SC, which is on the long SC(homologous synapsis of rob(13; 17) and 13, 17) moved, from one-fourth of long SC to one-tenth of it, near the end of 17 arm. These phenomenon is the result of a gradual length adjustment of lateral elements of 13,17 to the lateral element of the rob (13;17). We has discussed the mechanism of the trivalent synaptic adjustment, and it's important use to control the chiasmata and disjunction of the chromosomes.

Animals↗
PubMed1994

[Studies on deoxynivalenol contamination in grain and its products in Anhui Province].

Contamination of deoxynivalenol (DON) in wheat, corn, barley, and wheat flour produced in Anhui Province were examined with thin-layer chromatography in 1983-1991. In total, 672 specimens were determined, and 63.2% of them were contaminated by DON, with an average contents of 908.7 micrograms/kg (a range of 0-13330 micrograms/kg). The contamination of DON in wheat and wheat flour was more severe than that in corn (P < 0.01). There was highly significant difference in the contamination of DON in wheat produced in different areas and years, with a P-value less than 0.01 by ANOVA, but no significant difference in corn (P > 0.1). It suggested the contamination of DON correlated with the incidence of scabby wheat in that area during these years.

Food Contamination↗
PubMed1994

A study of c-myc oncogene expression and amplification in colorectal cancer.

Expression of c-myc oncogene transcripts in colorectal neoplasia was studied in paraffin embedded tissue sections from 25 patients undergoing surgery and from the rectal carcinoma cell line HR-8348 by using in situ hybridization, and its amplification was investigated in tumor and normal mucosa tissue from 25 coloproctomy samples by slot blot hybridization. Overexpression of this gene was seen in 78% (7/9) of the benign adenomas and 91% (20/22) of the malignancies sampled. There was no significant correlation between overexpression and the histologic type or grade, and no significant relationship between the level of expression and clinical stage was found, although overexpression was apparently more common in tumors with metastasis. Amplification of the gene was found in 0 of 4 benign adenomas and 7 of 22 malignancies. No obvious correlation was found between amplification and histological type or grade, though amplification was more frequent in tumors with metastasis. Amplification was also found in 2 adenomas with malignant change. The results suggest that multiple factors are involved in the progression of colorectal cancer, and in situ hybridization with a nonradiolabeled probe is useful in the detection of gene expression.

Adenocarcinoma↗
PubMed1994

L-Tryptophan in supraphysiologic concentrations stimulates collagenase gene expression in human skin fibroblasts.

BACKGROUND: Collagenase plays a critical role in regulating connective tissue breakdown in physiologic and pathologic processes. The expression of collagenase is modulated by a variety of biologic and pharmacologic agents. L-tryptophan is an essential amino acid with diverse biologic effects not shared by other amino acids. EXPERIMENTAL DESIGN: In this study, we examined the effects of L-tryptophan on collagenase gene expression in normal human skin fibroblasts using Northern hybridizations and transient transfection assays. RESULTS: The results indicate that L-tryptophan at supraphysiologic concentrations caused a marked increase in collagenase gene expression. The increase in collagenase mRNA levels was reversible, time- and dose-dependent, and was accompanied by enhancement of procollagenase synthesis and secretion. Parallel accumulation of mRNA for tissue inhibitor of metalloproteinase was also noted, whereas stromelysin mRNA levels remained undetectable. The enhancement of collagenase mRNA was specific for L-tryptophan, and was abrogated by alpha-amanitin or dexamethasone. The apparent half-life of collagenase mRNA transcripts was similar in cultures exposed to interleukin-1 beta or L-tryptophan. In contrast to interleukin-1 beta, L-tryptophan-induced increase in collagenase mRNA was not preceeded by expression of c-jun or c-fos. Transient transfection of human skin fibroblasts with a collagenase promoter, chloramphenicol acetyl transferase construct indicated marked dose-dependent increase in promoter activity with L-tryptophan. CONCLUSIONS: These results demonstrate that L-tryptophan in supraphysiologic concentrations is a potent inducer of collagenase gene expression in vitro at a transcriptional level by human skin fibroblasts.

Adult↗