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Biomedical subjects

L Li

Publications and source records attributed to L Li.

At least 667 records · Page 37Linked to original sources
PubMed2000

Fluidity and fatty acid components of erythrocyte membranes in diabetic retinopathy.

BACKGROUND: Recently, numerous anomalies of erythrocyte rheology and function have been reported in diabetic patients. These changes are thought to be related to the alteration of erythrocyte membrane fluidity and may play an important role in diabetic retinopathy (DR). Nonetheless, the principal factors contributing to fluidity change remain undetermined. The influence of erythrocyte membrane fatty acid components on membrane fluidity and retinopathy was evaluated in patients with type 2 diabetes. METHODS: The fatty acid components and fluidity of erythrocyte membranes in 63 patients with type 2 diabetes with and without retinopathy were examined using high-performance liquid chromatography and fluorescence polarization. RESULTS: The content and composition of erythrocyte membrane arachidonate (C20:4n-6) was significantly lower in diabetics than in controls, and diabetics had significantly increased erythrocyte membrane microviscosity compared with controls. Furthermore, membrane microviscosity was higher in diabetics with DR than those without DR. In the diabetic patients, arachidonic acid contents of erythrocyte membranes were significantly, inversely correlated with erythrocyte membrane microviscosity, fasting blood glucose, glycosylated hemoglobin, triglycerides and cholesterol, and positively correlated with the insulin sensitivity index. CONCLUSIONS: The results suggest that erythrocyte membrane fatty acid components may contribute to alterations in membrane fluidity in patients with type 2 diabetes. Alterations in membrane fluidity may play an important role in the development of diabetic microangiopathy.

Aged↗
PubMed2000

[Study of the factors of Cr(III) bioaccumulation on Spirulina platensis].

Some factors of Cr(III) bioaccumulation on Spirulina platensis were studied in detail. It was found that the bioaccumulation of Cr(III) on Spirulina platensis involved two steps: rapid adsorption and slow absorption. Chromic(III) compounds with weaker chemical bond had higher bioaccumulation efficiency. Under the same algal cell concentration, Cr(III) bioaccumulation rosed up with Cr(III) concentration. On the other hand, with Cr(III) concentration not changed, the total bioaccumulation of Cr(III) on Spirulina platensis increased with algal cell concentration, but the Cr(III) bioaccumulation on unit algae reduced. The study also showed that Spirulina platensis powder could bioaccumulate more Cr(III) than fresh Spirulina platensis, pH is a quite important factor and more suitable pH for Cr(III) bioaccumulation is 7. It was also proved that Cr(III) bioaccumulation benefited from the increase of temperature and light intensity. Cations had either stimulation or inhibition effects on the Cr(III) bioaccumulation on Spirulina platensis.

Bacterial Proteins↗
PubMed2000

[Estrogen receptor gene polymorphism and its association with clinicopathological manifestation of lupus nephritis].

OBJECTIVE: To investigate the distribution of estrogen receptor (ER) in patients with lupus nephritis (LN), and the association between ER gene polymorphism and the clinical and pathological features of the disease. METHODS: The Pvu II and Xba I restriction fragment length polymorphism (RFLP) of estrogen receptor gene were analyzed in 245 biopsy proven LN patients (58 males and 187 females) and 172 normal controls(101 males and 71 females) by PCR-RFLP. The clinical and pathological features of 49 male and 152 female LN patients with genotype PpXx or Ppxx, ppxx were then analyzed respectively. RESULTS: It was found that genotype PpXx and ppxx, Ppxx were three major genotypes of ER gene in both lupus patients group and control group. The distribution of ER gene polymorphism was quite different in lupus patients of different genders. The frequency of the PpXx genotype was significantly higher in male LN patients than in both the gender matched normal controls (P<0.05) and the female LN patients (P<0.05), while no difference was shown in the frequency of PpXx genotype between female LN patients and female controls. Interestingly, varied clinical and renal pathological features were also demonstrated in female patients with different genotypes of ER gene. CONCLUSION: The distribution of ER gene polymorphism in LN patients varies with gender. The PpXx genotype of ER gene may be associated with the susceptibility of LN in male. ER gene polymorphism is probably one of the genetic factors contributing to the development of clinical heterogeneity and sexually dimorphic manifestations of LN.

Adolescent↗
PubMed2000

Impact of aging and hyperbaric oxygen in vivo on guinea pig lens lipids and nuclear light scatter.

PURPOSE: To measure lipid compositional and structural changes in lenses as a result of hyperbaric oxygen (HBO) treatment in vivo. HBO treatment in vivo has been shown to produce increased lens nuclear light scattering. METHODS: Guinea pigs, approximately 650 days old at death, were given 30 and 50 HBO treatments over 10- and 17-week periods, respectively, and the lenses were sectioned into equatorial, cortical, and nuclear regions. Lipid oxidation, composition, and structure were measured using infrared spectroscopy. Phospholipid composition was measured using (31)P-NMR spectroscopy. Data were compared with those obtained from lenses of 29- and 644-day-old untreated guinea pigs. RESULTS: The percentage of sphingolipid approximately doubled with increasing age (29-544 days old). Concomitant with an increase in sphingolipid was an increase in hydrocarbon chain saturation. The extent of normal lens lipid hydrocarbon chain order increased with age from the equatorial and cortical regions to the nucleus. These order data support the hypothesis that the degree of lipid hydrocarbon order is determined by the amount of lipid saturation, as regulated by the content of saturated sphingolipid. Products of lipid oxidation (including lipid hydroxyl, hydroperoxyl, and aldehydes) and lipid disorder increased only in the nuclear region of lenses after 30 HBO treatments, compared with control lenses. Enhanced oxidation correlated with the observed loss of transparency in the central region. HBO treatment in vivo appeared to accelerate age-related changes in lens lipid oxidation, particularly in the nucleus, which possesses less antioxidant capability. CONCLUSIONS: Oxidation could account for the lipid compositional changes that are observed to occur in the lens with age and cataract. Increased lipid oxidation and hydrocarbon chain disorder correlate with increased lens nuclear opacity in the in vivo HBO model.

Aging↗
PubMed2000

Prothrombin activation is increased among asymptomatic carriers of the prothrombin G20210A and factor V Arg506Gln mutations.

The risk of venous thrombosis is increased in individuals who carry specific genetic abnormalities in blood coagulation proteins. Among Caucasians, the prothrombin G20210A and factor V Arg506Gln (FV R506Q) mutations are the most prevalent defects identified to date. We evaluated their influence on markers of coagulation activation among participants in the Second Northwick Park Heart Study, which recruited healthy men (aged 50-61 years) from nine general medical practices in England and Wales. They were free of clinical vascular disease and malignancy at the time of recruitment. Genotypes for the two mutations were analyzed using microplate array diagonal gel electrophoresis, and coagulation markers (factor XIIa; activation peptides of factor IX, factor X, and prothrombin; fibrinopeptide A) were measured by immunoassay. Factor VII coagulant activity and factor VIIa levels were determined by a functional clotting assay. Among 1548 men genotyped for both mutations, 28 (1.8%) and 52 (3.4%) were heterozygous for prothrombin G202 IOA and FV R506Q, respectively. The only coagulation marker that was significantly associated with the two mutations was prothrombin activation fragment FI+2 [mean +/- SD, 0.88 +/- 0.32 nmol/L in men with prothrombin G20210A (p = 0.002) and 0.89 +/- 0.30 in men with FV R506Q (p = 0.0001) versus 0.72 +/- 0.24 among non-carriers for either mutationl. This data provides conclusive evidence that heterozygosity for the prothrombin G20210A as well as the FV R506Q mutations in the general population leads to an increased rate of prothrombin activation in vivo.

Blood Coagulation Factors↗
PubMed2000

Muscarinic receptor-mediated pyridostigmine-induced neuronal apoptosis.

Pyridostigmine is a reversible cholinesterase (ChE) inhibitor that is associated with neurologic dysfunction involving both central and peripheral nervous systems. To determine the neurotoxic potential of pyridostigmine, rats were sacrificed at intervals after drug administration (0.5-1.85 mg/kg, i.p., twice daily for 4 days) and brains examined histologically. ChE inhibition was used as a biomarker of pyridostigmine activity. Using the in situ terminal deoxynucleotidyl transferase nick-end labeling of DNA fragments (TUNEL) method and electron microscopy, apoptotic brain cell death was noted in cerebral cortex over a dose range of 0.5-1.85 mg/kg and at the higher dose (1.85 mg/kg), apoptosis was also noted in striatum and hippocampus. These responses were blocked by pretreatment with atropine. Rat cortical cells in culture also underwent apoptosis when exposed to pyridostigmine (250 microM for 24 hr), indicating that the pyridostigmine can initiate apoptosis, independent of peripheral mechanisms. Pretreatment of cells with atropine (10 microM) inhibited pyridostigmine-induced apoptosis, confirming the response was mediated by muscarinic receptors. Short term treatment of rats with pyridostigmine (1.85 mg/kg twice daily for 4 days) induced a prolonged apoptotic response, which was evident in rat cortex up to 30 days after the last dose. Active apoptosis persisted, despite recovery of serum ChE activity. These in vivo and in vitro observations indicate that pyridostigmine can initiate a prolonged neurodegeneration.

Animals↗
PubMed2000

[Study on hepatitis C virus infection of peripheral blood mononuclear cells in chronic hepatitis C patients].

OBJECTIVE: To demonstrate HCV infection and replication in the peripheral blood mononuclear cells (PBMCs) of hepatitis patients by the methods of molecular biology, immunology and electron microscopy. METHODS: HCV RNA and antigens were detected in the PBMCs of 28 patients with chronic hepatitis C by RT-PCR, Immunohistochemistry and electron microscopy, respectively. RESULTS: The positive rate of HCV RNA and HCV antigens were 77.27% (17/22) and 75.00% (21/28), respectively. Two types of spherical HCV-like particles with diameter of approximately 65 nm and 110 nm were observed in cytoplasmic vesicles by electron microscopy in the PBMCs with high titer of HCV RNA and antigens in 10 patients. The budding and shedding of these particles could also be found in the cytoplasmic vesicles. Immunoelectron microscopy using antibodies against HCV core and NS(3) demonstrated that the particles contained HCV antigens. CONCLUSION: HCV can infect and replicate in the PBMCs of patients with chronic hepatitis C.

Hepacivirus↗
PubMed2000

[High-level expression of BYDV GAV coat protein gene in Escherichia coli].

The IPTG-inducible expression vector containing the BYDV GAV coat protein gene was constructed and transferred into E. coli BL21(DE3). High-level expression of the specific protein was achieved by IPTG induction. The results of SDS-PAGE and Western blotting show that the expression product which accumulates 19.5% of the total cellular proteins estimated by scanning is 24 kD BYDV GAV coat protein plus eleven amino acids of pET-5a.

Capsid↗
PubMed2000

Hypotension after coronary arterial occlusion induces regional expression of c-Fos protein in the rat brain.

The purpose of this study was to examine comprehensively and quantitatively the effects of sustained occlusion of the circumflex branch of the left coronary artery on neuronal expression of Fos, the protein product of the proto-oncogene c-fos, in the rat brain. Occlusion coronary artery induced a fall in mean arterial pressure of about 10-30%, maintained for a period of 60 min. Baroreceptors were activated by occlusion coronary artery-induced hypotension. In control rats treated with without coronary ligation, few Fos-positive cells were observed. Following coronary artery occlusion, there was a significant increase in the number of Fos-positive cells in the several brain regions. These brain regions containing Fos-positive neurons in rats treated with coronary artery occlusion included nucleus tractus solitarius (NTS), area postrema (AP), caudal and rostral ventrolateral medulla (VLM), lateral parabrachial nucleus (PBN), supraoptic nucleus (SON), paraventricular nucleus (PVN) and central nucleus of the amygdala (CE). This finding partly differs from previous studies where Fos expression occurred by other reasons such as hypovolemia, hemorrhage, nitroprusside or hydralazine etc. These results generally fit within an emerging understanding of brain circuitry underlying cardiovascular regulation.

Animals↗
PubMed2000

Pulmonary complications in patients with AIDS: a report from a Beijing hospital.

OBJECTIVE: The aim of this study was to improve the awareness of pulmonary complications in patients with AIDS. METHODOLOGY: Nine patients with AIDS with pulmonary involvement from March 1992 to March 2000 were analysed. RESULTS: Of the nine cases, there were eight cases complicated with Pneumocystis carinii pneumonia (PCP). The clinical presentation of PCP was fever (8/8), dyspnoea on exertion or at rest (7/8), and hypoxaemia with a mean PaO2 of 58 mmHg. Chest X-ray films showed bilateral diffuse interstitial or alveolar infiltrates. Pulmonary tuberculosis, tuberculous lymphadenitis and bronchial fungal infection were found in three cases. CONCLUSIONS: AIDS patients are at high risk of suffering from pulmonary complications, of which PCP is most common. If young patients who were healthy in the past suddenly suffered from pneumonia and respiratory failure, PCP should be considered. When opportunistic pulmonary infection is diagnosed under special circumstances, one should be alert to the possibility of AIDS and examine serum antihuman immunodeficiency virus (HIV) antibody.

AIDS-Related Opportunistic Infections↗
PubMed2000

[Foundational study of subcritical water chromatography].

AIM: To study the subcritical water chromatographic discipline of compounds with medium and high polarity on the capillary and packed column. METHODS: A packed and capillary subcritical water chromatography-FID detection system was built up. Six alcohols were well separated on a C18 column and the influence of temperature on chromatographic behavior of alcohols with different polarity was studied. The influence of temperature and pressure on chromatographic behavior of benzoic acid and gensenoside Rg1 on a SE-54 capillary column were also studied. RESULTS: Increasing temperature resulted in the decreasing polarity of mobile phase, shortened retention times of components separated, narrowed peak shape and improved tailing as well. CONCLUSION: Temperature programming could be used successfully to separate compounds with various polarity selectively. Thermostable capillary column could enlarge the range of temperature even more.

Chromatography, Liquid↗
PubMed2000

[Prognostic factors in granulosa cell tumor of the ovary].

OBJECTIVE: To study the effect of clinical and pathologic factors on prognosis for granulosa cell tumor of the ovary. METHODS: The clinical records and tumor sections of 100 patients with granulosa cell tumors of the ovary between 1958 and 1995 were reviewed. The relationship between age, stage, mitosis and the adjuvant therapy for early stage (stage I) were analyzed retrospectively. Patients with recurrent tumors were compared with patients who remained without disease, patients with early recurring tumors were compared with late recurring tumors. RESULTS: The overall 5 and 10 year survival rates were 80% and 72%. There were no significant difference between ages and survival (P > 0.05). The survival rates in stage I were 98% and 96% after 5 and 10 years, respectively, and in stages II were 70% and 60%, after 5 and 10 years, all of 4 patients with stage III-IV were dead of recurrent disease in 1 year. The frequency of observed mitosis influenced the survival rate: with less 5/10 high-power fields (HPF) the survival were 96% both at 5 and 10 years, with more or equal 5/10 HPF the 5 and 10 year survival rates were 58% and 36%, respectively (P < 0.01). No significant correlation could be established between the adjuvant therapy and 5 and 10 years survival in 56 stage I patients. There were 44 patients with recurrent disease in this group, median time to recurrence was 53 months. Late recurrence appeared in 8 cases. The significant differences in stage and abdominal mass were noted between the recurrent tumors and the group without disease (P < 0.05). When early and late recurring tumors were compared, statistically significant differences were again noted: early recurring tumors had higher mitotic rates and late stage, and late recurring tumors had lower mitotic rages and early stage. Patients without recurrent tumors were similar to the patients with early recurring tumors. CONCLUSIONS: Tumor stage and mitotic rate are the clinical and pathologic prognosticators in granulosa cell tumor. It is difficult to predict late recurrences using these clinical and pathologic parameters.

Adolescent↗
PubMed2000

[Molecular epidemiology analysis of HIV-1 subtype E strains found in Shenzhen, China].

OBJECTIVE: To investigate the prevalent status of HIV-1 subtype E epidemic among different populations in Shenzhen, China. METHODS: HIV-1 proviral DNA from peripheral blood mononuclear cells (PBMCs) of 3 HIV-infected individuals found in Shenzhen was amplified by nested-PCR. The C2-V3 and its flanking region (350-450 nucleotides) of HIV- 1 env gene were sequenced directly from the PCR products and analysed. RESULTS: These 3 cases were confirmed to be infected with HIV-1 subtype E strain (sz-E). The innergroups distance of sz-E was 2.6%. In comparison with the consensus sequence of international A-E subgroups and some of subtype B epidemic in China, the genetic distances among sz-E and each of A-D subgroups and some of subtype B were more than 24 %. Furthermore, the phylogenetic tree analysis showed that sz-E clustered closely to Econ. CONCLUSIONS: These findings suggested that the epidemic time for HIV-1 subtype E, which was mainly prevalent among IDUs population and some professional blood donors, had been about 2-3 years in Shenzhen.

China↗
PubMed2000

[Effect of Sindbis XJ-160 virus structural proteins on BHK-21 cell].

OBJECTIVE: To study the effect of Sindbis XJ-160 virus structural proteins on BHK-21 cell. METHODS: We constructed the expressing vector pcDNA3.1 ABC that contains the XJ-160 virus structural protein gene and then transfected it to BHK-21 cell. RESULTS: The expressed products can be detected by RNA dot blot hybridization or immUnofluorescent assay. The cytopathic effect was observed in BHK-21 cells transfected with pcDNA3.1 ABC. There was also condensed chromatin found accumulated. BHK-21 cell death and marked cell cycle changes were observed. CONCLUSIONS: These results indicate that cell apoptosis might be one of the mechanisms inducing cell death by XJ - 160 virus and its structural protein gene probably plays a role in this programmed cell death.

Apoptosis↗
PubMed2000

[Detection of hepatitis C virus RNA in the tissue of hepatocellular carcinoma by multiple detection system].

OBJECTIVE: Detection of hepatic HCV RNA in hepatocellular carcinoma (HCC) is difficult, since its expression is very low. Several techniques have been established. However, false positive and negative rates still exist. In this study, we applied several conventional and recently developed detection systems to determine the exact effect of HCV RNA on the development of RCC. METHODS: Immunohistochemistry for HCV core antigen and in situ hybridization for HCV RNA had been performed in 39 cases of HCC. IS-RT-PCR was applied for detection and localization of HCV RNA. We extracted microdissected liver tissues to detect HCV RNA separately in cancerous and pericancerous tissues so that the microscopic origin of the amplicons could be controlled. The serological tests including ELISA and RT-PCR for HCV also were performed in all cases. RESULTS: The positive rate by ELISA (30.8%) was not always consistent with that by RT-PCR(43.6%)from serum samples. The latter was much more sensitive and accurate to reflect existence of HCV RNA. Immunohistochemistry showed expression of RCV core antigen in 15 of 39 HCC cases. In pericancerous tissues, the signals were mainly localized in the cytoplasm of hepatocytes. However, translocated expression of HCV core protein was observed in the nuclei of tumor cells, the translocated rate was 73.3%. According to IS-RT-PCR, the positive signals were located mainly in the cytoplasm of cancer cells, the positive rate in HCC was 53.8%, expression of HCV RNA, serum HCV RNA level was detected to be low or negative. This suggested that serum HCV RNA was not always a good reflection of hepatic HCV RNA in HCC tissues. The microdissection RT-PCR described here gave an equal positive rate (59.0%) of HCV RNA in cancerous and pericancerous tissues. CONCLUSIONS: The high detection rate of HCV RNA in HCC specimens even from seronegative patients confirms the important role of HCV RNA during malignant transformation. IS-RT-PCR is a good detection and localization method to visualize HCV RNA in HCC tissues. The microdissection RT-PCR method has a distinct advantage and we anticipate this method will provide an important evidence to determine whether HCV play a direct or indirect role in hepatocarcinogenesis.

Adult↗
PubMed2000

[Effect of different source iron on piglet's growth, metabolism and environment].

In order to approach the effect of different source Fe on piglet's growth, metabolism and environment, an experiment was conducted with 158 suckling pigs from 15 litters, which were randomly allocated to group I, II and III, and fed with diet I (basal diet + FeSO4.H2O), II (basal diet + Fe-citric acid) and III (basal diet + Fe-methionine complex), respectively. Each of the diets contained 146 mg.kg-1 Fe. The results show that after the experiment ended, the body weight, daily increment, grades for appearance and behavior, hemoglobin concentration in blood, Fe-transferring albumen concentration in plasma, and Fe contents in plasma and liver of 35 days old piglets in group II and III were higher (P < 0.05 or P < 0.01) than those in group I, while the feed conversion, diarrhea incidence, fecal amount and its Fe content of the piglets in group II and III were lower (P < 0.05 or P < 0.01) than those in group I. The body weight and daily gain of the piglets in group III were also higher (P < 0.05) than those in group II, but no significant differences (P > 0.05) in other traits between group II and III. It is suggested that Fe-methionine complex and Fe-citric acid could improve piglet's health, growth and development, feed conversion, and physiological and biochemical parameters, increase the absorption and utilization of Fe by piglet's body, and decrease the fecal amount and its Fe content. Both of them should be effective and safe Fe sources for suckling pigs.

Animals↗
PubMed2000

[NO emission from winter wheat fields of rice-wheat rotation ecosystem in southeast China].

Measurements of NO emission from the winter wheat field of rice-wheat rotation ecosystem in southeast China during the whole period of wheat growth show that a higher NO emission was observed in spring than in autumn, and almost no emission in winter could be detected. Temperature was the most important factor determining the seasonal variation pattern of NO emission. Although the N fertilization might enlarge NO emission by a factor of 5-7, it could not modify the seasonal variation pattern. During the period of relatively weak plant activity, the diurnal variation pattern, with the maximum emission at 9:00-14:00, was determined by temperature. When plants luxuriated, however, the competition of NH4+ by plant uptake and by microbial nitrification led to a night-peak variation pattern, in which, the maximum diurnal emission usually occurred during 18:00 and 4:00 of next day, and the minimum at 8:00-16:00.

China↗