Biomedical subjects

H Lu

Publications and source records attributed to H Lu.

At least 91 records · Page 5Linked to original sources

PubMed2001

A role for salicylic acid and NPR1 in regulating cell growth in Arabidopsis.

Salicylic acid (SA) plays a key role in activating defenses and cell death during plant-pathogen interactions. In response to some pathogens, SA also limits the extent of cell death, indicating that it acts positively or negatively depending on the host-pathogen interaction. In addition, we previously showed that SA affects cell growth in the Arabidopsis defense-related mutants accelerated cell death 6-1 (acd6-1) and aberrant growth and death 2 (agd2). Using acd6-1, agd2 and two other defense-related mutants, lesion simulating disease 6 (lsd6), suppressor of SA-insensitivity (ssi1), we show here in detail that SA regulates cell growth by specifically affecting cell enlargement, endoreduplication and/or cell division. We find that SA can act either positively or negatively to regulate cell growth depending on the context in which signaling occurs. Additionally, Nonexpressor of PR 1 (NPR1), a key SA signaling protein important for regulating defenses and cell death, also acts to promote cell division and/or suppress endoreduplication during leaf development. We propose that SA interacts with multiple receptors or signaling pathways to control cellular alterations during normal development, pathogen attack and/or stress situations. We suggest that SA and NPR1 play broader roles in cell fate control than has previously been understood.

Arabidopsis↗

PubMed2001

Inorganic lead stimulates DNA synthesis in human astrocytoma cells: role of protein kinase Calpha.

As lead has been shown to activate protein kinase C (PKC), and gliomas are reported to be highly dependent on PKC for their proliferation, this study was undertaken to investigate whether lead may act as a mitogen in human astrocytoma cells, and to determine the role of PKC in this effect. Lead acetate (from 100 nM to 100 microM) induced a concentration- and time-dependent increase in DNA synthesis, as measured by incorporation of [methyl-3H]thymidine into cell DNA, without causing any cytotoxicity. Flow cytometric analysis showed that lead was able to stimulate the cell cycle transition from the G0/G1 phase to the S/G2 phase, resulting in increased percentage of cells in the latter phase. Western blot analyses showed that lead induced translocation of PKCalpha, but not of PKCepsilon or PKCzeta, from the cytosolic to the particulate fraction, with a concomitant increase in PKC enzyme activity. Prolonged exposure to lead caused down-regulation of PKCalpha, but not of PKCepsilon. The effect of lead on DNA synthesis was mediated through PKC as evidenced by the finding that two PKC inhibitors, GF 109203X and staurosporine, as well as down-regulation of PKC through prolonged treatment with 12-O-tetradecanoylphorbol 13-acetate, blocked lead-induced DNA synthesis. Further experiments using a pseudosubstrate peptide targeting classical PKCs and selective down-regulation of specific PKC isoforms indicated that the effect of lead on DNA synthesis was mediated by PKCalpha. Altogether, these results suggest that lead stimulates DNA synthesis in human astrocytoma cells by a mechanism that involves activation of PKCalpha.

Astrocytes↗

PubMed2001

NBP is the p53 homolog p63.

We previously identified a non-p53, p53-responsive DNA element (p53RE)-binding protein named NBP, functionally analogous to p53, from human cervical carcinoma Hela cells. Here we report a biochemical study demonstrating that this activity is the recently cloned p53 analog p63. NBP was purified through conventional and DNA affinity chromatography to apparent homogeneity with a prominent polypeptide migrating in between the 43 and 68 kDa positions on a SDS gel. This polypeptide immunoreacted with monoclonal anti-p63 but not anti-p53 or anti-p73 antibodies. Also, NBP co-purified with p63 through each step of fractionation, as detected with anti-p63 antibodies. DNA-protein complexes formed with purified NBP and p53RE-containing oligomers derived from the p21(waf1) promoter were supershifted by anti-p63 but not anti-p53 antibodies. Thus, these results demonstrate that NBP is encoded by the p53 homolog p63 gene.

Blotting, Western↗

PubMed2001

Transcription factor HIF-1 is a necessary mediator of the pasteur effect in mammalian cells.

The ability to respond to differential levels of oxygen is important to all respiring cells. The response to oxygen deficiency, or hypoxia, takes many forms and ranges from systemic adaptations to those that are cell autonomous. Perhaps the most ancient of the cell-autonomous adaptations to hypoxia is a metabolic one: the Pasteur effect, which includes decreased oxidative phosphorylation and an increase in anaerobic fermentation. Because anaerobic fermentation produces far less ATP than oxidative phosphorylation per molecule of glucose, increased activity of the glycolytic pathway is necessary to maintain free ATP levels in the hypoxic cell. Here, we present genetic and biochemical evidence that, in mammalian cells, this metabolic switch is regulated by the transcription factor HIF-1. As a result, cells lacking HIF-1alpha exhibit decreased growth rates during hypoxia, as well as decreased levels of lactic acid production and decreased acidosis. We show that this decrease in glycolytic capacity results in dramatically lowered free ATP levels in HIF-1alpha-deficient hypoxic cells. Thus, HIF-1 activation is an essential control element of the metabolic state during hypoxia; this requirement has important implications for the regulation of cell growth during development, angiogenesis, and vascular injury.

Adaptation, Physiological↗

PubMed2001

Interpretation of X chromosome dose at Sex-lethal requires non-E-box sites for the basic helix-loop-helix proteins SISB and daughterless.

For Drosophila melanogaster flies, sexual fate is determined by the X chromosome number. The basic helix-loop-helix protein product of the X-linked sisterlessB (sisB or scute) gene is a key indicator of the X dose and functions to activate the switch gene Sex-lethal (Sxl) in female (XX), but not in male (XY), embryos. Zygotically expressed sisB and maternal daughterless (da) proteins are known to form heterodimers that bind E-box sites and activate transcription. We examined SISB-Da binding at Sxl by using footprinting and gel mobility shift assays and found that SISB-Da binds numerous clustered sites in the establishment promoter Sxl(Pe). Surprisingly, most SISB-Da sites at Sxl(Pe) differ from the canonical CANNTG E-box motif. These noncanonical sites have 6-bp CA(G/C)CCG and 7-bp CA(G/C)CTTG cores and exhibit a range of binding affinities. We show that the noncanonical sites can mediate SISB-Da-activated transcription in cell culture. P-element transformation experiments show that these noncanonical sites are essential for Sxl(Pe) activity in embryos. Together with previous deletion analysis, the data suggest that the number, affinity, and position of SISB-Da sites may all be important for the operation of the Sxl(Pe) switch. Comparisons with other dose-sensitive promoters suggest that threshold responses to diverse biological signals have common molecular mechanisms, with important variations tailored to suit particular functional requirements.

Amino Acid Motifs↗

PubMed2001

Apigenin acts on the tumor cell invasion process and regulates protease production.

Apigenin is a widely distributed plant flavonoid and was proposed as an antitumor agent. In this study, we investigated the apigenin effects on the protease-mediated invasiveness in an estrogen-insensitive breast tumor cell line MDA-MB231. The results show that apigenin at 22.8-45.5 microM (2.5-10 micrograms/ml) strongly inhibited, in a dose-dependent manner, tumor cell invasion through Matrigel, cell migration, and cell proliferation. We show that apigenin treatment from 22.8 microM (2.5 micrograms/ml) led to a partial decrease in urokinase-plasminogen activator expression and to a total inhibition of phorbol 12-myristate 13-acetate-induced matrix metalloproteinase-9 secretion. We also demonstrate in the apigenin-treated cells a defective adhesion to Matrigel and a G2-M cell cycle arrest. Taken together, our results demonstrate that apigenin is a pleiotropic effector affecting protease-dependent invasiveness and associated processes and proliferation of tumor cells.

Antineoplastic Agents↗

PubMed2001

Intracerebroventricular insulin-like growth factor-1 decreases feeding in diabetic rats.

Insulin-like growth factor-1 (IGF-1) is a hormone that is important in the regulation of growth processes and additionally has been demonstrated to modulate metabolic and autonomic responses. Some of its effects are mediated by the central nervous system (CNS), and there are IGF-1 receptors dispersed throughout the CNS. Both IGF-1 and insulin alter peripheral metabolic and autonomic nervous activity by a central mechanism, and the well-defined role of insulin in the regulation of feeding, especially in diabetes, led us to investigate the effect of chronic central administration of IGF-1 on metabolic and feeding parameters in normal and diabetic rats. Normal and diabetic rats with intracerebroventricular cannulas were given IGF-1, insulin (0.5 nmol/animal), or artificial cerebrospinal fluid via cannula twice daily for 4 d. Blood samples were collected on d 2 and 4, and the body weights and food intake were recorded daily. IGF-1 administered intracerebroventricularly did not alter plasma glucose, insulin, body weight, or food intake in normal rats. However, in diabetic animals, IGF-1 decreased food intake but did not alter blood glucose or plasma insulin. In correlated studies, intracerebroventricular insulin decreased food intake in both normal and diabetic animals. From these studies, we conclude that IGF-1 may act centrally to decrease food intake in the hyperphagic diabetic animals but not in normal animals. This suggests that diabetic animals have an increased sensitivity to CNS IGF-1.

Animals↗

PubMed2001

Alteration of apoptosis in cleft palate formation and ectomesenchymal stem cells influenced by retinoic acid.

It has been shown that apoptosis is involved in normal embryonic development. The aim of the present study was to elucidate the role and alteration of apoptosis in the pathogenesis of cleft palate induced by retinoic acid (RA) and the ectomesenchymal stem (EMS) cells influenced by RA. RA was administered by gavage to pregnant C57BL/6N strain mice in the experimental group, and the control group received oil alone. Pregnant mice were killed at set periods of time thereafter and histologically analyzed. EMS cells explanted from the palatal shelves of embryonic mice were cultured and characterized by immunohistochemistry, growth curves and population-doubling time. The alterations of apoptosis of EMS cells and developing palatal shelves influenced by RA were evaluated by the terminal deoxynucleotidyl transferase-mediated UTP-biotin nick end-labeling (TUNEL) method. RA-treated mice showed formation of cleft palates resulted from the small size of the palatal shelves and their failure to lift. TUNEL staining showed that the number of apoptotic mesenchymal cells in palatal shelves in the RA-treated mice was increased significantly when compared with the control group. The primary culture of EMS cells proceeded successfully. The population-doubling time of RA-treated cells was much longer compared with non-treated EMS cells. RA also dramatically increased the number of apoptotic cells in EMS cells in vitro. We concluded that EMS cells are the crucial cells in palate development. RA could inhibit the proliferation and induced the apoptosis of EMS cells. The inhibition of growth and excess apoptosis of EMS cells may contribute to the formation of cleft palate and other orofacial congenital malformations.

Animals↗

PubMed2001

[Effects of emodin on hepatic fibrosis in rats].

OBJECTIVE: To investigate the effect of emodin on hepatic fibrosis in rats and study its possible mechanism. METHODS: The rat hepatic fibrotic model was induced by the subcutaneous injection of 40% CCl(4) (twice a week for 6 weeks). The fibrotic rats were treated with low-dose, mediate-dose and high-dose emodin (20, 40 and 80 mg/kg body weight, once a day for 42 days). Liver function, serum hyaluronic acid, laminin, and liver hydroxyproline were determined, Histopathological changes were examined by optical microscopy. The expression of alpha-smooth muscle actin (alpha-SMA) in liver tissue were detected by immunohistochemical techniques. RESULTS: Compared with model group, it revealed that in emodin-treated rats: (1) Liver functions was improved, alanine transaminase (ALT) and alkaline phosphatase (AKP) obviously reduced (P<0.05 or <0.01), total protein (TP) and albumin (ALB) significantly increased (P<0.05 or <0.01). (2) Serum hyaluronic acid and laminin markedly reduced (P<0.05 or <0.01). (3) Liver hydroxyproline were significantly decreased (P<0.05 or <0.01). (4) The degrees of fibrosis were reduced (P<0.05). (5) The expression of alpha-SMA in liver tissue were ameliorated. CONCLUSIONS: Emodin has an effect on hepatic fibrosis in rats. The effect may be related to slowing hepatocyte injury and inhibiting liver alpha-SMA expressions.

Actins↗

PubMed2001

[Adenovirus induced acute hepatitis in non-human primates after liver- directed gene therapy].

OBJECTIVE: To define the role of lymphocyte subsets and investigate the efficiency of immunosuppression regimen in acute hepatitis in non-human primates after adenovirus mediated gene therapy. METHODS: Six rhesus monkeys were infused with E-1 deleted adenovirus (Ad) expressing E coli lacZ gene or luciferase by various routes. Four of 6 animals were immunosuppressed by cyclophosphamide and predenisone. Two monkeys were transfected with a lacZ containing plasmid with lipofectamine as the control. Lymphocyte subsets CD3, CD4, CD8, CD20 and MHC molecule beta2-microglobulin(beta2-MG) and HLA-DR in liver tissues were studied using immunohistochemical staining. RESULTS: Staining of beta2-MG and HLA-DR on the membranes of hepatocyte and increased numbers of CD3+, CD4+ and CD8+ T-lymphocytes were detected in the livers after gene transfer, while B-lymphocytes were absent. The monkeys developed a mild to moderate transient hepatitis. This was accompanied by adenovirus-mediated T-cell proliferation and neutralizing antibodies to adenovirus. Drug-induced immune suppression enhanced the ability of adenovirus- mediated gene transfer. The development of acute hepatitis and the accompanying immune abnormalities were delayed in immunosuppressed monkeys until after discontinuation of immunosuppressive therapy. Lipofectamine-mediated gene transfer was inefficient and no immune response and liver damage were observed in the livers. CONCLUSIONS: Increased numbers of beta2-MG, HLA-DR, CD3, CD4 and CD8 antigen positive cells are presented in the monkey livers after adenovirus-mediated gene therapy and induce mild to moderate transient hepatic inflammation. Immunosuppression regimen may prolong transgene expression and delay the development of acute adenoviral hepatitis.

Adenoviridae↗

PubMed2001

[Clinicopathological and molecular genetic analysis in Chinese typical hereditary nonpolyposis colorectal cancer pedigrees].

OBJECTIVE: To investigate the clinicopathological and molecular genetic characteristics of Chinese hereditary nonpolyposis colorectal cancer (HNPCC) pedigrees. METHODS: Four Chinese HNPCC pedigrees were studied using microdissection, microsatellite instability analysis, immunohistochemistry staining and direct DNA sequencing for hMSH2 and hMLH1 genes. RESULTS: All five tumor tissues from 4 probands showed high level of microsatellite instability at more than 2 loci(RER + phenotype). Three of 4 cases lost hMSH2 protein expression and one case showed no hMLH1 protein expression. Three pathological germline mutations (2 on hMSH2 and 1 on hMLH1) were identified. CONCLUSIONS: Chinese typical HNPCC kindreds showed relatively frequent germline mutations of mismatch repair genes. Microsatellite instability analysis and immunohistochemistry staining might be the effective screening methods before direct DNA sequencing for the detection of mismatch repair genes. It is necessary to establish clinical criteria and molecular diagnostic strategies more suitable for Chinese HNPCC kindreds.

Adult↗

PubMed2001

[Relationship of abnormal umbilical artery flow velocity waveforms and placental pathology].

OBJECTIVE: To investigate the relationship of abnormal umbilical artery (UmA) flow velocity waveforms (FVWS) with placental weight, volume and all classes of villi and vessels. METHODS: Ten IUGR with abnormal umbilical artery(AA) were set as pathological group. Ten normal weight births with abnormal UmA FVWS(AN), 10 IUGR with normal UmA FVWS (NA), 10 normal weight births with normal UmA FVWS (NN) were selected as controls. Anti-alpha-SMA antibody was used to examine placental stem vessels and stem villi. The placental weight, volume, numbers of all classes of villi and vessels were compared. RESULTS: (1) Placental weight and volume in pathological group reduced significantly, while compared with AN (P < 0.01, P < 0.05, respectively), NA (P < 0.01, P < 0.001, respectively), and NN (all the P values < 0.001). (2) When the pathological group was compared with other 3 control groups with respect to the numbers of all classes of villi and vessels in placenta, the number of stem vessels reduced significantly (P < 0.05, P < 0.01, P < 0.001 respectively). The number of stem villi reduced significantly, compared with NA and NN (P < 0.01, P < 0.001, respectively). The number of stem villi did not change when compared with AN (P > 0.05). CONCLUSION: Abnormal UmA FVWS is related with placental weight, volume, all classes of villi and vessels. The reduction of villous and vascular number may be due to arrest of placental angiogenesis but not selective obliteration of vessels.

Actins↗

PubMed2001

The expression of AT1 receptor on hepatic stellate cells in rat fibrosis induced by CCl4.

OBJECTIVES: To assess the effect of an ACE inhibitor and an Ang II type 1 (AT1) receptor antagonist on preventing hepatic fibrosis induced by CCl4 in rats and to investigate whether there is the expression of AT1 receptors on hepatic stellate cells. METHODS: Studies were conducted in male Sprague-Dawley rats. Except for model group and control group, in three treated groups, either enalapril (5 mg/kg), or losartan (10 mg/kg), or enalapril + losartan were given to the fibrotic rats (daily gavage). Saline vehicle was given to the control group. After 6 weeks, liver fibrosis was assessed directly by hepatic morphometric analysis. The expression of AT1 receptors and alpha-smooth muscle actin (alpha-SMA) in liver tissue and isolated hepatic stellate cells (HSC) were detected by immunohistochemical techniques. RESULTS: Compared with the fibrosis in rats of the model group, rats treated with either enalapril or losartan, or a combination of two drugs, showed a limited expansion of the interstitium (P < 0.05), but no significant difference was observed among the three treated groups (P > 0.05). The expression of AT1 receptors was found in abundance in the fibrotic interstitium of the fibrotic rats, whereas in the normal control rats they were limited to the vascular wall. AT1 receptors were also expressed on activated HSC in culture plates. CONCLUSIONS: Angiotensin-converting enzyme inhibitors and AT1 blockers might slow the progression of hepatic fibrosis. Activated HSCs expressed AT1 receptors. Activation of RAS might be related to hepatic fibrogenesis induced by CCl4.

Alanine Transaminase↗

PubMed2001

[A study on the pathogenesis of Streptococcus mitis exotoxin].

OBJECTIVE: To study the isolation, purification and pathogenesis of Streptococcus mitis pyrogenic exotoxin causing toxic shock syndrome. METHODS: Streptococcus mitis isolated from patients' throat were shaking cultivated. After being centrifuged, the supernatant fluid of the culture was precipitated with 20%, 40%, 60%, 80% (NH(4))(2)SO(4) respectively and the fast protein liquid chromatography(FPLC) was used for the final step of purification. Rabbits receiving subcutaneous injection with respective purified proteins were monitored daily for fever. The ability of the purified proteins to enhance the susceptibility of the rabbits to lethal Escherichia coli endotoxin shock is recorded, when the endotoxin was injected intravenously 4 hours after administration of 10 microg Streptococcus mitis exotoxin. RESULTS: Only the protein precipitated by 20% (NH(4))(2)SO(4) (molecular weight is 34,000) from culture supernatant fluid was pyrogenic for rabbits (average temperature increase near 1 degrees C), and it can also cause the proliferation of rabbit splenocytes (mitogenicity). All the animals receiving subcutaneous injection of exotoxin containing purified proteins precipitated with higher concentrations of (NH(4))(2)SO(4) died within 16 approximately 29 hours after intravenous injection of the Escherichia coli endotoxin, demonstrating the enhanced susceptibility of the animals to lethal endotoxin shock. The control rabbits displayed none of these effects. CONCLUSION: Streptococcus mitis exotoxin is a novel streptococcal pyrogenic exotoxin.

Animals↗

PubMed2001

Radioprotective effects of miso (fermented soy bean paste) against radiation in B6C3F1 mice: increased small intestinal crypt survival, crypt lengths and prolongation of average time to death.

The radioprotective effect of miso, a fermentation product from soy bean, was investigated with reference to the survival time, crypt survival and jejunum crypt length in male B6C3F1 mice. Miso at three different fermentation stages (early-, medium- and long-term fermented miso) was mixed in MF diet into biscuits at 10% and was administered from 1 week before irradiation. Animal survival in the long-term fermented miso group was significantly prolonged as compared with the short-term fermented miso and MF cases after 8 Gy of 60Co-gamma-ray irradiation at a dose rate of 2Gy min(-1). Delay in mortality was evident in all three miso groups, with significantly increased survival. At doses of 10 and 12 Gy X-irradiation at a dose rate of 4 Gy min(-1), the treatment with long-term fermented miso significantly increased crypt survival. Also the protective influence against irradiation in terms of crypt lengths in the long-term fermented miso group was significantly greater than in the short-term or medium-term fermented miso and MF diet groups. Thus, prolonged fermentation appears to be very important for protection against radiation effects.

Animals↗

PubMed2001

[Studies on the manufacture and immunogenicity of purified rabies vaccines on humans Vero cell].

OBJECTIVE: Using Vero cell as basic cultural material to improve the quality of rabies vaccines and to produce rabies vaccines for humans. METHODS: CTN-1V10 strain were used for production. Vero cell of 150th generation were used for cultivation. Rotating cultivatal method with rotating bottle was used. Fluids with virus were collected at different time. Puritied rabies vaccine was produced on Vero cell after clarification, condensation, purification and extermination. A batch of vaccines made by this techniques were used for immunological observation. Sixty-three people were injected with this rabies vaccine according to the procedure of time of exposure. Thirty of them were injected with vaccines made in France (Verorab) while the others were injected with vaccines to be tested. Side effect and neutralizing antibody were recorded. RESULTS: The quality of this newly developed rabies vaccines has met the quality set by WHO. After all dosages of injection, the rates of positive antibody were both 100% in two groups. The neutralizing antibody among testing group was 11.94 IU/ml comparing with control as 11.69 IU/ml. CONCLUSION: Purified rabies vaccines on Vero cell for humans had reasonable manufacture technique and less little effect with good technological imnunogenicity.

Animals↗

PubMed2001

[Ossifying fibromyxoid tumor of soft parts: a clinicopathological analysis of eight cases].

OBJECTIVE: To study the morphological characteristics and immunophenotype of ossifying fibromyxoid tumor of soft parts (OFT) with a discussion of its histogenesis. METHODS: The clinical, pathological and immunohistochemical features of 8 cases of OFT were evaluated. RESULTS: All 8 cases were middle to old aged patients, ranged from 43 -- 78 years (mean 63 years). Clinically, the majority presented as slowly growing painless masses that located in subcutis of the proximal extremities. Histologically, the tumor was characterized by the following three unique features which have diagnostic value. (1) The tumor was well circumscribed and encapsulated with an incomplete bony shell composed of metaplastic bone within the capsule in most cases; (2) The tumor parenchyma consisted of lobules of variable size and cellularity. The tumor cells within each lobule were rounded to short spindled with pale-staining or eosinophilic cytoplasm; (3) The tumor cells arranged in nests, cords, or laciform pattern, and were embedded in a characteristic fibromyxoid to collagenized stroma. Immunohistochemically, all 7 cases tested were positive for vimentin and NSE, while 6 cases expressed S-100 protein and 2 cases expressed desmin. Follow-up information showed recurrences in two patients 2 and 15 years after local excision. CONCLUSIONS: OFT is a distinctive soft tissue tumor of potentially low-grade malignancy which occurred predominantly in middle to old aged patients. The characteristic bony shell, the unique cytological appearance and arrangement of the cells are pathognomonic features of OFT. Our immunohistochemical result supported a Schwann-cell origin.

Adult↗

PubMed2001

[Discovery and brief developmental history of electro -- convulsive therapy in mental diseases].

With its introduction in 1938, electro -- convulsive therapy (ECT) rapidly became accepted as a mainstream treatment. Its usage opened a new era treatment of mental diseases. ECT is a very effective treatment for major psychosis with high incidence such as endogenous depression, catatonia in schizophrenia and so on. Until recently it still has a place in psychiatric disorders even when effective antipsychotic chemicals are applied today.

Electroconvulsive Therapy↗