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Biomedical subjects

M Li

Publications and source records attributed to M Li.

At least 523 records · Page 29Linked to original sources
PubMed1999

Prognostic significance of apoptotic index in completely resected non-small-cell lung cancer.

PURPOSE: To evaluate the significance of apoptotic index (AI) as a prognostic factor after surgery for non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: A total of 236 patients who underwent surgery for previously untreated pathologic stage I to IIIa NSCLC between 1985 and 1990 were reviewed. AI was defined as the number of apoptotic cells, detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling, per 1,000 tumor cells. Proliferative index (PI) and aberrant p53 expression were also evaluated immunohistochemically. RESULTS: The 5-year survival rate for the lowest-AI group (AI < 5.0) was 74.7%; those for the lower-AI group (5.0 < or = AI < 11.0) and the higher-AI group (11.0 < or = AI < 25.0) were 51.6% and 57.8%, respectively. These survival rates were significantly lower than that of the lowest-AI group (P =.021 and P =.043, respectively). The highest-AI group (25.0 < or = AI), however, showed the most favorable prognosis, with a 5-year survival rate of 83.2%. Multivariate analysis confirmed that a moderate AI (5.0 < or = AI < 11.0 or 11.0 < or = AI < 25.0) was a significant factor to predict poor prognosis. The PIs for the lowest-, the lower-, the higher-, and the highest-AI groups were 32.3%, 48.0%, 54.3%, and 50.7%, respectively. The lowest-AI group showed a favorable prognosis because of its low PI, whereas the lower- and the higher-AI groups had a poor prognosis caused by increased cancer-cell proliferation. The highest-AI group showed the most favorable prognosis because apoptotic cell death overcame cell proliferation. No significant correlation was observed between AI and aberrant p53 expression. CONCLUSION: AI proved to be an independent prognostic factor in NSCLC.

Adenocarcinoma↗
PubMed1999

A low voltage-activated Ca2+ current mediates cytokine-induced pancreatic beta-cell death.

Insulin-dependent diabetes mellitus is characterized by the selective destruction of pancreatic beta-cells. Chronic treatment with cytokines induced a low voltage-activated (LVA) Ca2+ current in mouse beta-cells. The concomitant increase in the basal cytoplasmic free Ca2+ concentration ([Ca2+]i) was associated with DNA fragmentation and cell death. Antagonists of LVA Ca2+ channels prevented this elevation of basal [Ca2+]i and DNA fragmentation and reduced the percentage of cell death. Exposure to cytokines did not affect the profile of Ca2+ currents or basal [Ca2+]i in glucagon-secreting alpha-cells. An increased Ca2+ signal through LVA Ca2+ channels may thus be a key feature in cytokine-induced beta-cell destruction.

Animals↗
PubMed1999

Immunohistochemical localization of betacellulin, a new member of the EGF family, in normal human pancreas and islet tumor cells.

Betacellulin (BTC) purified from mouse beta cell tumor (betaTC-3) is a new member of the epidermal growth factor (EGF) family which can bind receptor tyrosine kinase, EGF receptor (erbB1) and erbB4. It has been demonstrated that proBTC mRNA was abundantly expressed in human pancreas tissue, and that BTC converted amylase-secreting rat acinar cell line (AR42J) into insulin-secreting cells, suggesting that BTC might be important for the growth and/or differentiation of islet cells. However, the cell type producing BTC in the pancreas has not been clarified. In this study, we examined the localization of BTC in human pancreas and islet cell tumors. Immunohistochemistry using specific antibodies to human BTC revealed that this protein was produced in alpha cells and duct cells, and probably in beta cells in normal adult pancreas. Furthermore, strong immunoreactivity to BTC was detected in primitive duct cells of the fetal pancreas, and both insulinoma and glucagonoma cells also showed positive immunoreactivity to BTC. EGF receptor (erbB1) and erbB4 were expressed mainly in islet and duct cells, and duct cells, respectively. These results demonstrate the localization of BTC and its receptors, and suggest that BTC may be one of the factors that have physiologically important roles such as growth and differentiation of islet cells in the human pancreas.

Adenoma, Islet Cell↗
PubMed1999

Drug discrimination under a concurrent fixed-ratio fixed-ratio schedule.

Pigeons were trained to discriminate 5.0 mg/kg pentobarbital from saline under a two-key concurrent fixed-ratio 10 fixed-ratio 40 schedule of food presentation, in which the fixed-ratio component with the lower response requirement was programmed to reinforce responding on one key after drug administration (pentobarbital-biased key) and on the other key after saline administration (saline-biased key). After responding stabilized, pigeons averaged 98% of their responses on the pentobarbital-biased key during training sessions preceded by pentobarbital, and they averaged 90% of their responses on the saline-biased key during training sessions preceded by saline. In test sessions preceded by doses of pentobarbital, chlordiazepoxide, or ethanol, pigeons switched from responding on the saline-biased key at low doses to responding on the pentobarbital-biased key at higher doses (the dose-response curve was quantal). High doses of phencyclidine produced responding on both keys, whereas pigeons responded almost exclusively on the saline-biased key after all doses of methamphetamine. These and previous experiments using concurrent reinforcement schedules to study drug discrimination illustrate that the schedule of reinforcement is an important determinant of the shape of dose-effect curves in drug-discrimination experiments.

Animals↗
PubMed1999

Unusual sonographic appearance of an epidermoid cyst of the testis.

Epidermoid cyst of the testis is a rare benign testicular tumor with varied sonographic appearances. We present a case in which two specific ultrasonographic patterns were seen: (1) an "onion ring" configuration of alternating hyperechoic and hypoechoic regions, described previously as being characteristic of this lesion, and (2) a heterogeneous region with multiple punctate hyperechoic foci.

Adult↗
PubMed1999

[Transcriptional regulation and subcellular localization of mutant androgen receptor in spinal and bulbar muscular atrophy].

Spinal and bulbar muscular atrophy (SBMA) is an adult form of motor neuronopathy with X-linked recessive hereditary trait, whose genetic mutation is an expansion of CAG repeats in the androgen receptor(AR) gene. The effect of the expansion of the polyglutamine stretch in AR protein has been investigated in several lines of experiments. The binding ability of androgen to AR is similar to control, but AR binding affinity to androgen responsive element(ARE) is increased in mutant AR, and AR-induced transcriptional activation decreases with increasing glutamine repeats. The subcellular localization of mutant AR may be variable among the tissues, but intranuclear inclusion of mutant AR occurs ubiquitously in neural and non-neural tissues. Therefore the expansion in the polyglutamine stretch may induce some pathological aberrations in transcriptional regulation and translocation of AR in SBMA.

Adult↗
PubMed1999

[In vitro aggregation and cellular toxicity of mutant androgen receptor protein in spinal and bulbar muscular atrophy].

Spinal and bulbar muscular atrophy (SBMA) is an X-linked motor caused by expansion of a polyglutamine repeat within the androgen receptor(AR). We have studied the mutant AR in an in vitro system, and find aggregation of the AR protein to occur in a polyglutamine repeat length-dependent manner and the cellular toxicity to be coupled to aggregation. In addition we find intranuclear inclusions in nonneural tissues as well as affected neural tissues. These results indicate that the polyglutamine repeat length-dependent aggregation may be a likely molecular basis for the toxic gain of AR function that produces neuronal degeneration in SBMA. However, there is a recent report which suggests that inclusions did not correlate with cell death. Thus the mechanism of toxic gain of function remains to be elucidated.

Cell Death↗
PubMed1999

Acute pentylenetetrazol injection reduces rat GABAA receptor mRNA levels and GABA stimulation of benzodiazepine binding with No effect on benzodiazepine binding site density.

The effects of a single convulsive dose of pentylenetetrazol (PTZ, 45 mg/kg i.p.) on rat brain gamma-aminobutyric acid type A (GABAA) receptors were studied. Selected GABAA receptor subunit mRNAs were measured by Northern blot analysis (with beta-actin mRNA as a standard). Four hours after PTZ, the GABAA receptor gamma2-mRNA was decreased in hippocampus, cerebral cortex, and cerebellum; alpha1-mRNA was decreased in cerebellum; and beta2 subunit mRNA was decreased in cortex and cerebellum. The alpha5 subunit mRNA level was not altered. Those mRNAs that had been reduced were increased in some brain regions at the 24-h time point, and these changes reverted to control levels by 48 h. PTZ effect on GABAA receptors was also studied by autoradiographic binding assay with the benzodiazepine agonist [3H]flunitrazepam (FNP), the GABAA agonist [3H]muscimol, and the benzodiazepine antagonist [3H]flumazenil. There was an overall decrease in [3H]FNP binding 12 but not 24 h after PTZ treatment. In contrast, [3H]muscimol binding was minimally affected, and [3H]flumazenil binding was unchanged after PTZ treatment. Additional binding studies were performed with well-washed cerebral cortical homogenates to minimize the amount of endogenous GABA. There was no PTZ effect on specific [3H]FNP binding. However, there was a significant reduction in the stimulation of [3H]FNP binding by GABA. The results showed that an acute injection of PTZ caused transient changes in GABAA receptor mRNA levels without altering receptor number but affected the coupling mechanism between the GABA and benzodiazepine sites of the GABAA receptor.

Animals↗
PubMed1999

[Liver support effect of experimental extracorporeal bioartificial liver].

OBJECTIVE: To establish an extracorporeal bioartificial liver support system (EBLSS) and study its support effect for fulminant hepatic failure (FHF). METHODS: The EBLSS consists of three parts: human liver cells (hepatocytes, nonparenchymal hepatocytes) isolated and cultured by extracorporeal two-stage perfusion and spheroidal aggregates methods respectively, hollow fiber bioreactor, and supplementary circulation unit, which was employed to support the FHF model dogs. RESULTS: Compared with the control dogs treated with EBLSS but without liver cells, the survival time of artificial liver support dogs was significantly prolonged, the changes of blood pressure, heart rate and ECG were slower, and the serum ammonia and lactate levels were significantly lower at the 3 and 5 hr. In addition, a good viability of human liver cells was noted after 5 hr experiment. CONCLUSION: This EBLSS has played the metabolic role of cultured heman hepatocytes, is capable of compensating the function of the liver, and might provide effective artificial liver support and therapy for patients with FHF or severe hepatitis.

Animals↗
PubMed1999

[The genotype-based haplotype relative risk and transmission disequilibrium test analyses of familial febrile convulsions].

OBJECTIVE: To confirm the linkage of familial febrile convulsions to the short arm of chromosome 6(6p) or the long arm of chromosome 8(8q). METHODS: The authors finished genotyping of Pst I locus on the coding region of heat shock protein (HSP) 70, 5'untranslated region of HSP70-1, 3' untranslated region of HSP70-2, D8S84 and D8S85. The data were processed by the genotype-based haplotype relative risk(GHRR) and transmission disequilibrium test(TDT) methods in PPAP. RESULTS: Some signs of association and disequilibrium between D8S85 and FC were shown by GHRR and TDT. CONCLUSION: A suspect linkage of familial febrile convulsions to the long arm of chromosome 8 has been proposed.

Chromosomes, Human, Pair 6↗
PubMed1999

[A case-control study on the dietary risk factors of upper digestive tract cancer].

OBJECTIVE: To understand the effect of dietary factors in Yangzhong, Jiangsu Province-a high prevalence area in China. METHODS: A case-control study on 209 cases of upper digestive tract cancer was conducted. There were 68 cases of esophageal cancer, 69 cases of cardiac cancer and 72 cases of other gastric cancers including 129 males and 80 females aged 35-79 under the study. RESULTS: It is revealed that intake of pickled vegetables increases the ORs of esophageal, cardiac and other gastric cancers (OR = 2.82, OR = 5.17, OR = 2.92, respectively). It is also concluded that the intake of leftovers can elevate the ORs of esophageal and cardiac gastric cancer (OR = 1.88 and OR = 1.90) and over consumption of salt also elevates the OR of cardiac cancer (OR = 1.87). However, drinking green tea may decrease the ORs of esophageal and other gastric cancers (OR = 0.20 and OR = 0.28) while fruits consumption may reduce the OR of esophageal cancers (OR = 0.51). CONCLUSION: Tumors from upper digestive tract have some relations with diet factors but the effects vary with the differences of tumor sites, dose of exposure and area, etc.

Adult↗
PubMed1999

A Compression Algorithm for DNA Sequences and Its Applications in Genome Comparison.

We present a lossless compression algorithm, GenCompress, for genetic sequences, based on searching for approximate repeats. Our algorithm achieves the best compression ratios for benchmark DNA sequences. Significantly better compression results show that the approximate repeats are one of the main hidden regularities in DNA sequences. We then describe a theory of measuring the relatedness between two DNA sequences. Using our algorithm, we present strong experimental support for this theory, and demonstrate its application in comparing genomes and constructing evolutionary trees.

Journal Article↗
PubMed1999

[Clinical analysis of 25 cases of primary vaginal malignant melanoma].

OBJECTIVE: To investigate the influence of tumor size and different treatment method on the prognosis of primary vaginal malignant melanoma. METHOD: The clinical data of 25 patients with primary malignant melanoma of the vagina admitted to our hospital from Dec. 1964 to Oct. 1997 were analysed retrospectively. RESULTS: The overall 2-year and 5-year survival rate were 21.4% and 5.4%, respectively. The mean survival time for patients with tumor diameter < or = 2 cm was 27.7 months and for patients with tumor > 2 cm, 9.7 months (P < 0.05). The mean survival time was 19.5 months for the 17 cases treated with surgery and 8.3 months for another 8 cases who did not received surgery (P < 0.05). Multi-variate Cox regression with tumor size, surgical treatment, chemotherapy and immunotherapy also showed that tumor diameter and surgery were significant variables statistically for survival time (both P < 0.05). CONCLUSION: The prognosis of the primary malignant melanoma of vagina is poor and can be improved if the disease could be diagnosed early and combined modality therapy with emphasis on surgery be given.

Adult↗
PubMed1999

[Study of relation between ureaplasma urealyticum and fetal intrauterine growth retardation].

OBJECTIVE: To study the influences of Ureaplasma Urealyticum (UU) infection to fetal intrauterine growth. METHODS: Polymerase Chain Reaction was used to detect UU in samples of cervical secretions, umbilical blood and placenta. The study group included 50 women with neonatal birth weight below 2,500 g, 50 women with newborns birth weight above 2,500 g served as control group. RESULTS: Positive rate of UU in samples of cord blood and placenta and placental chorioamnionitis in study group were higher than that in the control group (P < 0.005 and P < 0.05). There was no significant difference of UU positive rate in cervical samples between two groups. The positive rate of UU in cases with chorioamnionitis was higher than that of cases with negative UU infection (P < 0.05). CONCLUSION: UU may interfere fetal intrauterine growth through infecting umbilical blood and placenta.

Adult↗
PubMed1999

[Expression of apoptosis regulatory protein bcl-2 and bax in endometrium of polycystic ovary syndrome].

OBJECTIVE: To study the expression and implication of apoptosis regulatory protein bcl-2 and bax in endometrium of polycystic ovary syndrome (PCOS). METHODS: The apoptosis regulatory protein expression of bcl-2 and bax protein in endometrium were investigated by immunohistochemical method in 18 PCOS and 27 normal subjects proliferative phase 10 and secretory phase 17. RESULTS: Bcl-2 expression was higher in PCOS than that both in control proliferative phase (P < 0.05) and secretory phase (P < 0.001). Bax expression was not significantly different between PCOS and controls (P > 0.05). CONCLUSIONS: The higher bcl-2 protein expression inhibits the endometrium apoptosis and plays an important role in the abnormal proliferative changes of endometrium in PCOS.

Adult↗