Biomedical subjects

Li Zhou

Publications and source records attributed to Li Zhou.

At least 109 records · Page 6Linked to original sources

PubMed2003

Copper in the silk formation process of Bombyx mori silkworm.

Evidence is presented here that cupric ions play a part in the natural spinning of Bombyx mori silk. Proton induced X-ray emission studies revealed that the copper content increased from the posterior part to the anterior part of silk gland, and then further increased in the silk fiber. Spectrophotometric analysis demonstrated that cupric ions formed coordination complexes with silk fibroin chains while Raman spectroscopy indicated that they induced a conformation transition from random coil/helix to beta-sheet. Taken together these findings indicate that copper could play a role in the natural spinning process in silkworms.

Animals↗

PubMed2003

Incorporation of a venturi device in electrospray ionization.

Electrospray ionization has grown to be one of the most commonly used ionization techniques for mass spectrometry, and efforts continue to improve its performance. Typically, the sprayer tip must be very close to the entrance orifice of the mass spectrometer in order to maximize the conduction of ions from the sprayer into the mass spectrometer. However, because of space-charge repulsion, most ions never reach the sampling orifice. In this work, an industrial air amplifier, for which the working mechanism is based on venturi and coanda effects, was added between an electrospray ionization source and a time-of-flight mass spectrometer. When a series of reserpine solutions (0.5, 1.0, 5.0, and 10.0 microM) were monitored using mass spectrometry, an over 5-fold increase in m/z 609.3 ion intensity was measured for a separation distance of 14 mm between the electrospray tip and interface capillary inlet, as compared to when the electrospray tip was in its normal position 1 mm in front of the inlet without the amplifier. When a voltage was applied to the air amplifier to further assist in focusing the electrosprayed ions, an approximately 18-fold increase in m/z 609.3 ion intensity was obtained. In addition, a 34-fold reduction in method detection limit was observed.

Journal Article↗

PubMed2003

Methylated metabolites of arsenic trioxide are more potent than arsenic trioxide as apoptotic but not differentiation inducers in leukemia and lymphoma cells.

Treatment with arsenic trioxide (As(2)O(3)) by inducing apoptosis and partial differentiation of acute promyelocytic leukemia (APL) cells results in clinical remission in APL patients resistant to chemotherapy and all-trans-retinoic acid. As(2)O(3) (iAs(III)) is methylated in the liver to mono- and dimethylated metabolites, including methylarsonic acid, methylarsonous acid, dimethylarsinic acid, and dimethylarsinous acid. Methylated trivalent metabolites that are potent cytotoxins, genotoxins, and enzyme inhibitors may contribute to the in vivo therapeutic effect of iAs(III). Therefore, we compared the potency of iAs(III) and trivalent metabolites using chemical precursors of methylarsonous acid and dimethylarsinous acid to induce differentiation, growth inhibition, and apoptosis. Methylarsine oxide (MAs(III)O) and to a lesser extent iododimethylarsine were more potent growth inhibitors and apoptotic inducers than iAs(III) in NB4 cells, an APL cell line. This was also observed in K562 human leukemia, lymphoma cell lines, and in primary culture of chronic lymphocytic leukemia cells, but not human bone marrow progenitor cells. Apoptosis was associated with greater hydrogen peroxide accumulation and inhibition of glutathione peroxidase activity. MAs(III)O, in contrast to iAs(III), did not induce PML-retinoic acid receptor alpha degradation, or restore PML nuclear bodies or differentiation in NB4 cells. In a cocultivation experiment, hepatoma-derived HepG2 cells, but not NB4 cells, methylate radiolabeled iAs(III). Methylated metabolites released from HepG2 cells are preferentially accumulated by NB4 cells. This experimental model suggests that in vivo hepatic methylation of iAs(III) may contribute to As(2)O(3)-induced apoptosis but not differentiation of APL cells. MAs(III)O as an apoptotic inducer should be considered in the treatment of other hematologic malignancies like lymphoma.

Apoptosis↗

PubMed2003

Role of the Arabidopsis glucose sensor HXK1 in nutrient, light, and hormonal signaling.

Glucose modulates many vital processes in photosynthetic plants. Analyses of Arabidopsis glucose insensitive2 (gin2) mutants define the physiological functions of a specific hexokinase (HXK1) in the plant glucose-signaling network. HXK1 coordinates intrinsic signals with extrinsic light intensity. HXK1 mutants lacking catalytic activity still support various signaling functions in gene expression, cell proliferation, root and inflorescence growth, and leaf expansion and senescence, thus demonstrating the uncoupling of glucose signaling from glucose metabolism. The gin2 mutants are also insensitive to auxin and hypersensitive to cytokinin. Plants use HXK as a glucose sensor to interrelate nutrient, light, and hormone signaling networks for controlling growth and development in response to the changing environment.

Amino Acids, Cyclic↗

PubMed2003

[Molecular basis of preventive effect of human apolipoprotein-1 on murine vascular smooth muscle cell proliferation and lipid deposition induced by oxidized low density lipoprotein].

OBJECTIVE: To study the molecular basis of preventive effect of human apolipoprotein-1 (h-apoA-1) on vascular smooth muscle cell (vSMC) proliferation and lipid deposition induced by oxidized low density lipoprotein (ox-LDL). METHODS: Smooth muscle cells originated from the aortae of h-apo-A-1 transgenic mice were cultured and divided into 2 groups, one group was stimulated by ox-LDL (tester) and the other group was used as control (driver). Subtractive hybridization was used to enrich the genes differentially expressed in the vSMCs induced by ox-LDL. A subtractive library was thus established and confirmed by colony hybridization in situ and dot blot analysis. 15 clones out of the 57 differentially expressed clones were randomly chosen foe sequencing and homology analysis. The whole-length cDNA library of vSMC induced by ox-LDL was established using SMART technique. RESULTS: Three expression sequence tags (EST), all correlated with immune system, were confirmed: C1-inhibitor (C1-INH), lectin, and T cell receptor beta. The whole-length cDNA library contained 1.5 x 10(6) pfu/ml primary recombinants with insertions 0.5 - 3 kb in length. CONCLUSION: The 3 EST may be involved in the mechanism of atherogenesis by ox-LDL and the mechanism of the function of h-ApoA-1 in retarding the progression of atherogenesis induced by ox-LDL.

Animals↗

PubMed2003

Elimination of shrimp endogenous peroxidase background in immunodot blot assays to detect white spot syndrome virus (WSSV).

False positive results were obtained in immunodot blot assays to detect white spot syndrome virus when horseradish peroxidase-conjugated sheep anti-mouse immunoglobin (Ig) serum was used as a secondary antibody with 3-3'-diaminobenzine tetrahydrochloride dihydrate as the detection substrate. The cause was considered to be a reaction of shrimp endogenous peroxidase (POD) with the substrate. In experiments designed to inhibit POD activity, 9 different reagents were used at different concentrations and for different treatment times. EDTA, sodium azide, HEPES-Na, NaHSO3, H2O2 and phenylthiourea (PTU) were able to inhibit POD activity by 44, 60, 64, 67, 79, and 90%, respectively. Phenylmethylsulfonyl fluoride did not inhibit POD, and neither periodic acid nor H2O2 in methanol were appropriate due to the formation of flocculant precipitates when added to shrimp extracts. It was concluded that of the treatments tested, 10 mM PTU for 2 h yielded optimal inhibition and that such pretreatment of samples eliminates false positive results in immunodot blot assays.

Animals↗

PubMed2003

Genetic heterogeneity and ploidy level analysis among different gynogenetic clones of the polyploid gibel carp.

BACKGROUND: Some triploid and tetraploid clones have been identified in the gynogenetic gibel carp, Carassius auratus gibelio Bloch, by karyotypic and cytologic analyses over many years. Further, 5-20% males and karyotypic diversity have been found among their natural and artificial populations. However, the DNA contents and the relation to their ploidy level and chromosome numbers have not been ascertained, and whether normal meiosis occurs in spermatogenesis needs to be determined in the different clones. METHODS: The sampled blood cells or sperms were mixed with blood cells from chicken or individual gibel carp and fixed in 70% pre-cooled ethanol overnight at 4 degrees C. The mixed cell pellets were washed 2-3 times in 1x phosphate buffered saline and then resuspended in the solution containing 0.5% pepsin and 0.1 M HCl. DNA was stained with propidium iodide solution (40 microg/mL) containing 4 kU/ml RNase. The measurements of DNA contents were performed with Phoenix Flow Systems. RESULTS: Triploid clones A, E, F, and P had almost equal DNA content, but triploid clone D had greater DNA content than did the other four triploid clones. DNA content of clone M (7.01 +/- 0.15 pg/nucleus) was almost equal to the DNA content of clone D (5.38 +/- 0.06 pg/nucleus) plus the DNA content of common carp sperm (1.64 +/- 0.02 pg/nucleus). The DNA contents of sperms from clones A, P, and D were half of their blood cells, suggesting that normal meiosis occurs in spermatogenesis. CONCLUSIONS: Flow cytometry is a powerful method to analyze genetic heterogeneity and ploidy level among different gynogenetic clones of polyploid gibel carp. Through this study, four questions have been answered. (a) The DNA content correlation among the five triploid clones and one multiple tetraploid clone was revealed in the gibel carp, and the contents increased with not only the ploidy level but also the chromosome number. (b) Mean DNA content was 0.052 pg in six extra chromosomes of clone D, which was higher than that of each chromosome in clones A, E, F, and P (about 0.032 pg/chromosome). This means that the six extra chromosomes are larger chromosomes. (c) Normal meiosis occurred during spermatogenesis of the gibel carp, because DNA contents of the sperms from clones A, P, and D were almost half of that in their blood cells. (d) Multiple tetraploid clone M (7.01 +/- 0.15 pg/nucleus) contained the complete genome of clone D (5.38 +/- 0.06 pg/nucleus) and the genome of common carp sperm (1.64 +/- 0.02 pg/nucleus).

Animals↗

PubMed2003

Age-dependent increase of NF-kappaB translocation and PDGF-B expression in aortic endothelial cells of hypercholesterolemic rats.

The objective of this study was to determine whether there was an age-dependent difference in promoting nuclear translocation of NF-kappa B and platelet derived growth factor expression in aortic endothelial cells between two groups of Wistar rats of 2 and 10 months in age, respectively, accompanied by hypercholesterolemia. The serum cholesterol levels became significantly higher in the older rats after taking a cholesterol-enriched diet for 16 weeks (129.3+/-11.9 vs. 194.5+/-22.6 mg/dl, P<0.01). The increase in total cholesterol levels were due to an elevation of LDL cholesterol since serum HDL cholesterol concentrations were similar in rats on either a high cholesterol- or a standard diet. Immunohistologic staining revealed nuclear translocation of NF-kappaB in aortic endothelial cells of rats was responsible for a high cholesterol uptake by cells. PDGF-B production was also increased in the endothelial cells of these animals as identified by situ hybridization and immunohistologic staining. Interestingly, the intensity of PDGF-B expression in the 10 months old rats was markedly higher than those of 2 months old. Taken together, these findings provide evidence that there was an elevation of serum cholesterol levels coinciding with an increase of PDGF-B expression in older rats, in which NF-kappaB might be an important transcription factor in mediating a hypercholesterolemia-induced PDGF-B expression.

Aging↗

PubMed2003

Genomic organization and comparative sequence analysis of the mouse and human FRS2, FRS3 genes.

The signaling adapter proteins FRS2 and FRS3 are implicated in the transmission of extracellular signals from nerve growth factor (NGF) or fibroblast growth factor (FGF) receptors to the Ras/mitogen-activated protein kinase signaling cascade. This study presents the genomic sequence and exon-intron organization of the mouse FRS2 and FRS3 loci as well as their evolutionary conservation with their human counterparts. Both FRS2 and FRS3 contain 5 coding exons spanning over 7 kb of genomic sequence with similar exon sizes and organization. Comparative genomic sequence analyses show a highly conserved genomic organization between mouse and human in both FRS2 and FRS3 genes. Non-coding sequences, highly conserved between mouse and human, were identified in the FRS3 introns that may potentially function as regulatory elements. To assay potential differences in their patterns of expression, RT-PCR analysis was used to assay FRS2 and FRS3 expression in the developing embryo and neural tube (NT) during the time of neurogenesis.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Ataxia and male sterility (AMS) mouse. A new genetic variant exhibiting degeneration and loss of cerebellar Purkinje cells and spermatic cells.

We describe a novel genetic variant mouse that exhibited ataxia and male sterility, named the AMS mouse. It arose in autoimmune-prone MRL/lpr strain and putative ams mutation showed an autosomal recessive inheritance pattern. Clinical symptoms were first discernible at approximately 21 days of age and consisting of subtle sway of the trunk followed by failure to maintain still posture and appearance of abnormal walk, but no further worsening was noted with advancement of age. The abnormal motor coordination was ascribed to almost complete loss of Purkinje cells of the cerebellum. The cell loss in the Purkinje cell layer began before onset of ataxia and rapidly progressed towards near-complete loss by 6 weeks of age. Another symptom was male sterility due to severe oligozoospermia associated with cellular degeneration during spermatic differentiation in the seminiferous tubules. Thus, the effects of the genetic variation were apparent in two different organs after the development of their basic histological structures, and degeneration and loss of particular cell types in these two tissues produced overt clinical symptoms. Genetic pleiotropism, provided that the nature of genetic variation is of a single gene mutation, is discussed.

Animals↗

PubMed2003

Intratubular germ cell neoplasia of unclassified type occupying the whole testis accompanied by a small mature teratoma and metastatic choriocarcinoma and Sertoli cell-only tubules in the other testis.

A 19-year-old man with mild mental retardation was diagnosed as having metastatic choriocarcinoma and a testicular tumor. Histopathological examination of the resected testis revealed the presence of a small lesion of mature teratoma but no trace of choriocarcinoma. The remaining seminiferous tubules were atrophic and lined by large atypical germ cells, which were diagnosed as intratubular germ cell neoplasia of the unclassified type (IGCNU). A small area with prominent tubules was also observed. Within this lesion, the tubules were dilated and contained several layers of cells with central necrosis. Immunohistological comparison of staining for several biological markers (Ki-67, c-kit and placental alkaline phosphatase) between cells in the atrophic tubules and those in the dilated tubules indicated a progression of the latter cells to cells with a more proliferative ability. In the opposite testis, examined at autopsy after death due to metastatic choriocarcinoma, all seminiferous tubules were lined by Sertoli cells only. It was therefore assumed that the germ cell tumor of the combined histological type had primarily arisen in the background of IGCNU, and that choriocarcinoma had spontaneously regressed. The early onset of these testicular neoplastic lesions strongly indicates their occurrence under the genetic background of gonadal dysplasia, the Sertoli cell-only syndrome. The possible relation of gonadal disease to mental retardation in this patient is also discussed.

Adult↗

PubMed2003

Studying Chinese suicide with proxy-based data: reliability and validity of the methodology and instruments in China.

This study examined the reliability and validity of the instruments as used in the psychological autopsy method in China. With data from 130 informants on 66 completed suicides and 130 informants on 66 normal community controls and 66 controls themselves, the validity was examined by comparing the responses of informants and the responses (gold standards) of the target participants in the control group. All the tested instruments were shown to be reliable, and proxy respondents were generally good judges of targets' suicidal intention, social support, depression, life events, personality traits, and mental disorders. Additionally, interrater reliabilities of the five interviewers were very good on selected scales. This study has laid a partial foundation for future psychological autopsy projects to be held in Chinese culture.

Adult↗

PubMed2003

Blockade of tumor necrosis factor-related apoptosis-inducing ligand exacerbates type 1 diabetes in NOD mice.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is expressed in different tissues and cells, including pancreas and lymphocytes, and can induce apoptosis in various tumor cells but not in most normal cells. The specific roles of TRAIL in health and disease remain unclear. Here we show by cDNA array analyses that TRAIL gene expression is upregulated in pancreatic islets during the development of autoimmune type 1 diabetes in nonobese diabetic (NOD) mice and in Min6 islet beta-cells activated by TNF-alpha + interferon-gamma. However, stimulation of freshly isolated pancreatic islets or Min6 cells with TRAIL did not induce their apoptosis. TRAIL blockade exacerbates the onset of type 1 diabetes in NOD.Scid recipients of transferred diabetogenic T-cells and in cyclophosphamide-treated NOD mice. TRAIL inhibits the proliferation of NOD diabetogenic T-cells by suppressing interleukin (IL)-2 production and cell cycle progression, and this inhibition can be rescued in the presence of exogenous IL-2. cDNA array and Western blot analyses indicate that TRAIL upregulates the expression of the cdk inhibitor p27(kip1). Our data suggest that TRAIL is an important immune regulator of the development of type 1 diabetes.

Animals↗

PubMed2003

Right trisectionectomy for primary liver cancer.

AIM: To evaluate the value of right trisectionectomy, previously named right trisegmentectomy, in the treatment of primary liver cancer by summarizing our 13-year experience for this procedure. METHODS: Thirty three primary liver cancer patients undergoing right trisectionectomy from Apr. 1987 to Dec. 1999 were investigated retrospectively. The impacts in survival of patients by cancerous biological behavior, such as tumor thrombi and satellite nodules, were discussed respectively. All right trisectionectomies were performed under normothermic interruption of porta hepatis at single time. Ultrasonic dissector (CUSA system 200) was used in dissection of hepatic parenchyma from Nov. 1992, instead of finger fracture. RESULTS: 1-, 3- and 5-year survival rates were 71.9 %, 40.6 % and 34.4 %, respectively. The longest survival term with free cancer was 150 months (alive). There were no significant differences in survival curves between cases with and without tumor thrombi (right branch of portal vein) and satellite nodules. Operative mortality was 3.0 % (1/33). Main surgical complications occurred in 5 cases. CONCLUSION: Right trisectionectomy should be regarded as an effective and safe procedure for huge primary liver cancers and is worth using more widely.

Adult↗

PubMed2003

[Brain-derived neurotrophic factor mRNA expressions in rat brain induced by short-term in vivo exposure to deltamethrin].

OBJECTIVE: To elucidate the mechanism of damage on central nervous system (CNS) caused by deltamethrin (DM). METHODS: The mRNA and protein expressions of brain-derived neurotrophic factor (BDNF) in the cerebral cortex and hippocampus of the rats exposed to DM were measured by retro-transcription-polymerase chain reaction (RT-PCR), dot blot, flow cytometry analysis and immunohistochemistry. RESULTS: After exposure to DM at high-dose (DM1, 25.0 mg x kg(-1) x d(-1), i.p.) once and low-dose (DM2, 12.5 mg x kg(-1) x d(-1), i.p.) for 5 days, the level of BDNF mRNA and protein expression in the cerebral cortex and hippocampus of the rats increased significantly. The levels of BDNF mRNA and protein expression in the cerebral cortex and hippocampus measured by of RT-PCR in the rats with DM1 and DM2 were higher than those in the controls by 48% and 56%, and 59% and 54%, respectively. And, those measured by dot blot in the rats with MD1 and MD2 were 186% and 161%, and 148% and 158% of those in the controls, respectively, basically similar to those measured by RT-PCR. Flow cytometric analysis showed that the levels of BDNF mRNA and protein expression in the cerebral cortex and hippocampus in the rats with DM1 and DM2 were higher than those in the controls by 53% and 89%, and 45% and 46%, respectively. Immunohistochemical analysis showed that protein expression in the cerebral cortex of the rats with DM1 and DM2 were 129% and 147% of those in the controls, same as the flow cytometric analysis, but those were significantly higher in the hippocampus mainly in the CA1 and DG areas of the rats with MD1 and the CA3 and DG areas of the rats with DM2. CONCLUSIONS: DM could induce BDNF mRNA and protein expression in the cerebral cortex and hippocampus of the rats, which could play an important role in repairing of nerve damage.

Animals↗

PubMed2003

[On hybrid embryo culture in vitro of Syringa L].

Syringa L. is the famous ornamental shrub in China, but its embryo always dies before seed mature during cross breeding, and hence, the breeding work is very difficult. The main object of this study is using embryo culture in vitro to get the seedling directly and to improve the succeed rate of cross breeding. The factors that influenced the embryo culture were researched in detail. The results showed that the optimal medium for embryo culture was Monnier, and the second was MS or LS, which meant that the embryo of Syringa needed abundant macroelements and microelements, especially Ca2+ and K+. The optimal sugar concentration was 50 g.L-1. At this level, the sugar could offer enough nutrition and high osmotic pressure for embryo. When the embryo age was 50-60 days, the culture was easy to be succeed. At this time, the cotyledon in ovule began to form, or organ began to differentiation, so, the embryo was very easy to germinate, and the seedling was very easy to form. Proper coconut milk, glutamic acid or glutamine, and activated charcoal could improve the germination and growth of the embryo. When the BA of low concentration (0.01 mg.L-1) was joined in the medium, the germination rate could be improved. The best NAA concentration was 0.01 mg.L-1.

Amino Acids↗

PubMed2003

[Multi-modal serial therapy for primary liver cancer in senile patients: a report of 153 cases].

OBJECTIVE: To study the feasibility and validity of multi-modal serial therapy for primary liver cancer in senile patients. METHODS: 153 senile primary liver cancer patients (>or= 60 years) were given multi-modal serial therapy from June 1993 to December 2000. Hepatectomy was performed in 37, deep cryosurgery in 32 and non-operative therapy in 84 (intervention as chief therapy in 81, combined local and intervention therapy in 3). The multi-course intervention therapy was given postoperatively in hepatectomy and cryosurgery groups, while bioimmunotherapy and traditional Chinese medicine were used in all groups. RESULTS: The 1-, 3- and 5-year survival rates in the hepatectomy group were 78.4%, 46.4% and 35.7%, without operative mortality. The 1- and 3- and 5-year year survival rates in the cryosurgery group were 64.5%, 40.9% and 25.0% with mortality of 3.1%. Among patients with non-operative therapy, the 1- and 3- and 5-year year survival rates in intervention group were 47.5%, 23.5% and 4.3%. The operative mortality was 1.2%. The 3 patients who received combined local and intervention therapy have survived for 2.5, 3.8 and 7.1 years. CONCLUSION: Multi-modal serial therapy with surgical treatment as the chief means, being precise in the effect and good in safety, is feasible and valid for primary liver cancer in senile patients.

Aged↗

PubMed2003

[Detection of NF-kappaB activation and platelet-derived growth factor-B expression in endothelial cells of hypercholesterolemic rats].

OBJECTIVE: To detect whether the activation of nuclear factor-kappa B (NF-kappaB) in endothelial cells induced by mm-LDL can promote platelet-derived growth factor-B (PDGF-B) expression in vitro, and whether it is also present in hypercholesterolemic rats in vivo, influence of age on NF-kappaB and PDGF-B signal transduction pathway. METHODS: Established hypercholesterolemic rat model by feeding with a high-cholesterol ration. The activation of NF-kappaB in aortic endothelial cells was identified by immunohistochemical staining, the expression of PDGF-B mRNA and PDGF-B protein were examined using in situ hybridization and immunohistochemistry respectively. RESULTS: In comparison with the control rats, a positive immunostaining of NF-kappaB in nuclei of aortic endothelial cells of the experimental rats was detected after a high cholesterol ration for 6 weeks. The number of endothelial cells expressing PDGF-B mRNA increased and the intensity was dependent upon the duration of high-cholesterol intake. NF-kappaB translocation (0.461 +/- 0.075 vs. 0.350 +/- 0.094, P < 0.05) and PDGF-B expression in 10-month old Wistar rats were more remarkable than that of 2-month old rats after having cholesterol for 16 weeks. Immunohistochemical staining for PDGF-B gave a similar result (0.230 +/- 0.040 vs. 0.185 +/- 0.037, P < 0.001). CONCLUSIONS: Hypercholesterolemia is capable of activating nuclear translocation of NF-kappaB and promoting expression of PDGF-B in rat aortic endothelial cells in vivo, this coincided with the results obtained in ox-LDL or mm-LDL experiments on endothelial cells in vitro. This phenomenon is much more evident in 10-month old rats which indicates that age might have a close relationship with NF-kappaB - PDGF-B signal transduction pathway.

Active Transport, Cell Nucleus↗