Glucocorticoids-potent modulators of astrocytic calcium signaling

Glucocorticoids are the first line of choice in the treatment of cerebral edema associated with brain tumors. High-dose glucocorticoids reduce the extent of edema within hours, often relieving critical increases in intracranial pressure, but the mechanisms by which glucocorticoids modulate brain water content are not well-understood. A possible target of action may be glucocorticoid receptor-expressing astrocytes, which are the primary regulators of interstitial ion homeostasis in brain. In this study, we demonstrate that two glucocorticoids, methylprednisolone and dexamethasone, potentiate astrocytic signaling, via long-range calcium waves. Glucocorticoid treatment increased both resting cytosolic calcium (Ca2+i) level and the extent and amplitude of Ca2+ wave propagation two-fold, compared to matched controls. RU-486, a potent steroid receptor antagonist, inhibited the effects of methylprednisolone. The glucocorticoid-associated potentiation of Ca2+ signaling may result from upregulation of the cellular ability to mobilize Ca2+ and release ATP, because both agonist-induced Ca2+i increments (via ATP and bradykinin) and ATP release were proportionally enhanced by glucocorticoids. In contrast, neither gap junction expression (as manifested connexin 43 immunoreactivity) nor functional coupling was significantly affected by methylprednisolone. Confocal microscopy revealed both the expression of glucocorticoid receptors and nuclear translocation of these receptors when exposed to methylprednisolone. We postulate that the edemolytic effects of glucocorticoids may result from enhanced astrocytic calcium signaling.

[Pregnancy of patients conceived within one year after chemotherapy for gestational trophoblastic tumor]

OBJECTIVE

To explore the risk of pregnancy in patients conceived within one year after successful chemotherapy for gestational trophoblastic tumor.

METHODS

22 patients conceived within one year after chemotherapy were followed up and analysed about abnormal pregnant result, wastage rate and the time of interval between chemotherapy and pregnancy.

RESULTS

Among 22 cases, 9 cases were full term birth, 6 cases were wastage. The wastage rate was 27.3%. The wastage rate of these patients conceived within half a year was higher than one year (P < 0.05). 1 repeated hydatidiform mole and one post term choriocarcinoma occurred in 22 patients. They both were conceived within 5 months after chemotherapy.

CONCLUSIONS

Preservation of fertility is feasible in patients suffering from choriocarcimona and invasive mole. But these patients should practise contraception at least half a year after chemotherapy, and it's better to advise patients to take contraception for one year.

Plexins are a large family of receptors for transmembrane, secreted, and GPI-anchored semaphorins in vertebrates

In Drosophila, plexin A is a functional receptor for semaphorin-1a. Here we show that the human plexin gene family comprises at least nine members in four subfamilies. Plexin-B1 is a receptor for the transmembrane semaphorin Sema4D (CD100), and plexin-C1 is a receptor for the GPI-anchored semaphorin Sema7A (Sema-K1). Secreted (class 3) semaphorins do not bind directly to plexins, but rather plexins associate with neuropilins, coreceptors for these semaphorins. Plexins are widely expressed: in neurons, the expression of a truncated plexin-A1 protein blocks axon repulsion by Sema3A. The cytoplasmic domain of plexins associates with a tyrosine kinase activity. Plexins may also act as ligands mediating repulsion in epithelial cells in vitro. We conclude that plexins are receptors for multiple (and perhaps all) classes of semaphorins, either alone or in combination with neuropilins, and trigger a novel signal transduction pathway controlling cell repulsion.

[Effect of alum on intestinal microecological balance in mice]

OBJECTIVE

To observe the degree of microecological imbalance induced by alum in normal intestine of mice, and the bacterial adherence activity in the intestine of the mice administered orally with alum.

METHODS

The mice were medicated orally with alum of small and large doses (0.25 g/kg and 1 g/kg) for 8 weeks, then 5 weeks after stopping administration of alum, microflora analysis and bacterial adherence to intestinal mucosal epithelial cells were carried out respectively.

RESULTS

Eight weeks after administration with alum, the counts of Bifidobacteria and Lactobacilli decreased significantly, but the numbers of pathogenetic E. Coli increased significantly. The adherence rate of Bifidobacteria to the enterocytes of mice reduced markedly, but E. Coli was on the contrary of Bifidobacteria. Five weeks after the ceasing of medication, the intestinal flora were balanced, the adherence rate of both strains as mentioned above recovered to normal level.

CONCLUSION

The imbalance of intestinal flora of mice administered with alum for a long time were only the transient change of bacterial counts. The imbalance of intestinal flora and the adherence rate of bacteria regained normal status five weeks after cancelling action factor.

The role of glutathione in p-aminophenol-induced nephrotoxicity in the mouse

p-Aminophenol (PAP) produces nephrotoxicity in rats through a mechanism presumably involving oxidation and conjugation with glutathione (GSH). Recently it was found that PAP also causes nephrotoxicity in mice as evidenced by elevated blood urea nitrogen (BUN) and serum creatinine levels. The objective of this study was to further investigate the mechanism and elucidate the role of GSH in PAP-induced nephrotoxicity in the mouse. Male C57BL/6 mice injected i.p. with various doses of PAP were sacrificed at 12 hr for measurement of BUN and serum creatinine levels and determination of the extent of renal cortical nonprotein sulfhydryl (NPSH) and GSH depletion. PAP depleted renal cortical NPSH content in a dose- and time-dependent manner. Depletion of NPSH in mouse kidney did not occur at PAP doses below 600 mg/kg. Buthionine sulfoximine, an inhibitor of GSH synthesis, decreased nephrotoxicity. Ascorbate, a reducing agent, prevented PAP-induced nephrotoxicity and attenuated renal cortical NPSH depletion. However, acivicin and aminooxyacetic acid, inhibitors of gamma-glutamyltranspeptidase and beta-lyase, respectively, did not prevent toxicity in the mouse. Piperonyl butoxide, an inhibitor of cytochrome P-450 enzymes, enhanced nephrotoxicity and renal cysteine depletion but not GSH depletion. The results suggest that PAP-induced nephrotoxicity in the mouse may involve oxidation and formation of a GSH conjugate.

Amino acids within the extracellular matrix (ECM) binding region (201-218) of rat insulin-like growth factor binding protein (IGFBP)-5 are important determinants in binding IGF-I

The highly conserved N-and C-terminal domains of IGFBPs are believed to participate in IGF binding, but only recently have some of the critical residues in the IGFBP sequence involved in ligand binding been identified. Here we describe two highly conserved amino acids in the C-terminal domain of rat IGFBP-5 that are involved in binding IGF-I. Site-directed mutagenesis was used to produce two mutants, G203K and Q209A, of rIGFBP-5. Relative to wild-type rIGFBP-5, an 8-fold reduction in affinity for human IGF-I was found for recombinant G203K protein in both IGF-I ligand blots and solution phase ligand binding assays, and a 7-and 6-fold reduction for Q209A respectively. This shows that Gly203 and Gln209 in IGFBP-5 are important determinants in binding IGF-I, and due to their complete conservation in all IGFBP sequences, we suggest that they are likely to be involved in binding IGF-I in all six binding proteins. In addition, these two non-basic residues lie within the ECM binding region (201-218) of IGFBP-5, demonstrating that the C-terminus contains partially overlapping IGF-I and ECM binding sites. We therefore propose that heparin binding to basic amino acids in IGFBP-5 between 201-218 may physically occlude subsequent interaction between IGF-I and Gly203/Gln209, and that this may explain previous work of others showing reduced affinity of ECM bound IGFBP-5 for IGF-I.

Increased p53 protein expression in human failing myocardium

BACKGROUND

The p53 gene is a tumor-suppressor gene which involves apoptosis and cell-cycle arrest under certain stress stimulate. However, the status of the p53 gene expression in human myocardium in congestive heart failure (CHF) remains unclear. Therefore, the current study was designed to investigate the expression of the p53 protein in human myocardium in normal subjects and in patients with severe CHF.

METHODS

Human ventricular cardiac tissue was obtained from 7 normal subjects and 7 end-stage CHF patients during cardiac transplantation. The expression of p53 protein was determined by immunohistochemical staining. The cardiac apoptosis was determined by TUNEL staining.

RESULTS

The p53 protein was minimally stained in normal human ventricular cardiomyocytes. In contrast, the staining density and positive stained nuclear (%) of p53 was significantly increased in ventricular cardiomyocytes of patients with severe CHF. Apoptosis in CHF human myocardium also markedly increased.

CONCLUSIONS

The significantly increased expression of p53 in CHF human cardiomyocytes suggests that p53 may play an important pathophysiological role in the process of CHF through mechanisms involving myocardial apoptosis.

Genetic local search algorithm for optimization design of diffractive optical elements

We propose a genetic local search algorithm (GLSA) for the optimization design of diffractive optical elements (DOE's). This hybrid algorithm incorporates advantages of both genetic algorithm (GA) and local search techniques. It appears better able to locate the global minimum compared with a canonical GA. Sample cases investigated here include the optimization design of binary-phase Dammann gratings, continuous surface-relief grating array generators, and a uniform top-hat focal plane intensity profile generator. Two GLSA's whose incorporated local search techniques are the hill-climbing method and the simulated annealing algorithm are investigated. Numerical experimental results demonstrate that the proposed algorithm is highly efficient and robust. DOE's that have high diffraction efficiency and excellent uniformity can be achieved by use of the algorithm we propose.

[Studies on gel electrophoresis of soluble protein and two kinds of isodynamic enzyme in hongqu from different producing areas]

OBJECTIVE

To investigate the consanguinity between 12 strains of Monascus(MS 01-12) separated and purified from different samples of Hongqu collected from 12 areas in China and the variant strain of Monascus(MS 18) mutated from M. purpureus.

METHOD

Gel electrophoresis of soluble protein, esterase and superoxide dismutase(SOD) was used to study the consanguinity between strains MS 01-12 and the variant strain MS 18.

RESULTS

The electrochromatophoreses of soluble protein, esterase and SOD in the 12 strains (MS 01-12) are identical, but in the variant strain MS 18 are remarkably different. The results are consistent with those of morphological studies.

CONCLUSION

Strains MS 01-12 are the identical species M. purpureus, but strain MS 18 is different from strains of MS 01-12, or a variant of M. purpureus.

Voltammetric response and determination of DNA with a silver electrode

A current from DNA was obtained using a silver electrode with low overpotentials for the first time. Experimental results revealed that the voltammetric response of DNA was attributed to the redox reactions of purine bases. It was also shown that such a method provided a convenient and practical way to determine DNA. A linear dependence of the peak currents on ssDNA concentrations was observed in the range 0.5-2.5 microg/mL. The relative standard deviation was 3.5% for six successive determinations at 0.5 microg/mL. The detection limit was 50 ng/mL. Influence of the structure and the length of the nucleic acids on their electrochemical behavior was discussed. In view of the merits of the silver electrode, this technique might provide new possibilities for further electrochemical research and determination of nucleic acids.

[Studies on pharmacognostic identification and quality control standards for hongqu]

OBJECTIVE

To develop effective methods for quality control of the traditional Chinese drug Hongqu.

METHOD

TLC and microscopic identification were performed. HPLC was used to determine the content of lovastatin.

RESULT

A lot of hyphae and spores in Hongqu were observed under microscope. The spot of lovastatin was found on the TLC chromatogram. The standard curve of lovastatin by HPLC was linera in the range of 5 micrograms/ml-100 micrograms/ml. The average recovery of lovastatin was 96.4%, RSD 3.68%, n = 5.

CONCLUSION

The methods are simple, sensitive and accurate. These studies provide the scientific basis for quality evaluation and quality control of Hongqu.

Panax ginseng protects the testis against 2,3,7, 8-tetrachlorodibenzo-p-dioxin induced testicular damage in guinea pigs

OBJECTIVES

To investigate histopathologically the beneficial effects of Panax ginseng extract on guinea pig testes damaged by 2,3, 7,8-tetrachlorodibenzo-p-dioxin (TCDD).

MATERIALS AND METHODS

Ninety guinea pigs were divided into six equal groups. The normal controls (group 1) received vehicle and saline; group 2 received TCDD (1 microgram/kg) intraperitoneally; group 3 and 4 received 100 or 200 mg/kg per day of Panax ginseng water extract (PG-WE) intraperitoneally for 28 days from 1 week before TCDD injection; groups 5 and 6 received PG-WE for 14 days from 1 week after TCDD treatment.

RESULTS

The gain in body weight was less in groups treated with TCDD than in controls. Moreover, the body weight of group 2 decreased from 14 days after TCDD exposure, while that of groups 3 and 4 increased; there was no decrease in body weight in groups 3-6. The decrease in testicular weight caused by TCDD was prevented by PG-WE. Light microscopy showed smaller tubules and late maturation arrest in group 2; electron microscopy showed a dissolution of the germinal epithelium, disrupted tight junctions between adjacent Sertoli cells, and altered germ cells at all developmental stages. The maturation arrest in germ cells caused by TCDD was ameliorated in groups 3-6. The testes almost completely recovered in groups 3 and 4 and there was some therapeutic effect of PG-WE in groups 5 and 6.

CONCLUSIONS

These results confirm the protective and therapeutic effects of Panax ginseng on atrophy and testicular damage induced by TCDD, providing evidence that ginseng might be a useful agent in preventing and treating testicular damage induced by environmental pollutants.

A recombinant prodrug type approach for triggered delivery of streptokinase

A novel prodrug type approach for triggered delivery of thrombolytic drugs without their associated hemorrhagic effects has been proposed. Presented herein is a rapid communication of preliminary observations that suggest the feasibility of the approach. A hirulog-streptokinase fusion protein (termed "HSK") possessing active thrombolytic functions has been successfully produced using recombinant DNA technology. The prodrug and triggered release features of this approach have been demonstrated by the inhibition of the plasminogen-activating activity of HSK via binding with thrombin and reversal of this inhibition by hirudin.

Phospholipase C-gamma and phosphoinositide 3-kinase mediate cytoplasmic signaling in nerve growth cone guidance

Expression of rat TrkA in Xenopus spinal neurons confers responsiveness of these neurons to nerve growth factor (NGF) in assays of neuronal survival and growth cone chemotropism. Mutational analysis indicates that coactivation of phospholipase C-gamma (PLC-gamma) and phosphoinositide 3-kinase (PI3-kinase) by specific cytoplasmic domains of TrkA is essential for triggering chemoattraction of the growth cone in an NGF gradient. Uniform exposure of TrkA-expressing neurons to NGF resulted in a cross-desensitization of turning responses induced by a gradient of netrin-1, brain-derived neurotrophic factor (BDNF), or myelin-associated glycoprotein (MAG) but not by a gradient of collapsin-1/semaphorin III/D or neurotrophin-3 (NT-3). These results, together with the effects of pharmacological inhibitors, support the notion that there are common cytosolic signaling pathways for two separate groups of guidance cues, one of which requires coactivation of PLC-gamma and PI3-kinase pathways.

[Histology and physiological function of dogs after extirpation of bronchi]

OBJECTIVE

To investigate the effect of extirpation of bronchi on histology and physiological function.

METHODS

21 dogs were divided in to two groups: control (3) and experimental (18). After bronchi extirpation one week, two weeks, one month, three months, six months, and twelve months, we used specimens to test the pulmonary surfactant (PS) and to observe the morphological changes.

RESULTS

After the operation, the residual lung nearby the operative area had traumatic changes. Around the aforementioned area, the structure of lung was normal. Specially after six months, the lung returned to good status. We found that two weeks after operation, the contents of PS increased remarkably (P < 0.05). After one month the parameter returned to normal (P > 0.05).

CONCLUSIONS

The residual lung after bronchi extirpation had ventilation and air-exchange functions. The lung function was preserved directly.

Direct gap junction communication between malignant glioma cells and astrocytes

Gap junctions are intercellular channels that connect the interiors of coupled cells. We sought to determine the extent to which malignant glioma cells form gap junction channels with astrocytes from either adult human brain or rat forebrain. The astrocytic gap junction protein, connexin 43 (Cx43), was identified in immunoreactive plaques at areas of cell-to-cell contact between cocultured glioma cells and astrocytes. These gap junction plaques were composed of functional channels, because extensive dye coupling was evident between the glioma cells and astrocytes from both human and rat brain. Calcium signaling was also readily transmitted from glioma cells to astrocytes and vice versa. In live rat brain, injection of glioma cells prelabeled with the gap junction tracer, dicarboxy-dichlorofluorescein, revealed extensive dye transfer to host cells, demonstrating that malignant glioma cells directly couple with normal brain cells. These observations suggest that intercellular communication via gap junctions may play a role in regulating cellular interactions during tumor invasion. In fact, the presence of gap junctions between astrocytes and glioma cells was sufficient to induce a transformation of astrocytic phenotype. Astrocytes cocultured with C6 glioma cells overexpressing Cx43 were significantly smaller and expressed a lower level of glial fibrillary acidic protein than astrocytes cocultured with otherwise identical mock-transfected, gap junction-deficient C6 cells. Thus, direct cellular coupling with glioma cells result in a phenotypic transformation of astrocytes that may contribute to the susceptibility of surrounding tissue to glioma invasion.

Antiviral nucleoside drug delivery via amino acid phosphoramidates

Stable and water soluble amino acid phosphomonoester amidates of AZT were synthesized and shown to have potent anti-HIV-1 activity. Intracellular and cell extract metabolism studies revealed that these compounds are likely to be enzymatically converted to the corresponding monophosphates. In addition, we have shown that the half life and tissue distribution of a phosphoramidate of AZT is 5 and 10-fold greater, respectively, than AZT.

[Clinical significance of changes of interleukin 6 level in pregnancy induced hypertension]

OBJECTIVE

To assess the clinical significance of changes of interleukin-6 (IL-6) level in patients with pregnancy induced hypertension (PIH).

METHODS

IL-6 level in urine and blood were measured by sandwich enzyme labeled immunosorbent assay (ELISA) in 82 patients with PIH and 30 normal pregnant women.

RESULTS

Blood IL-6 level in severe PIH patients was significantly higher than that in mild PIH patients and normal pregnant women. IL-6 level of urine in PIH patients were significantly higher than that in normal pregnant women and was associated with the severity of disease. There was a positive correlation between urinary IL-6 level and severity of renal damage in PIH.

CONCLUSION

Determination of IL-6 level is useful to understand the severity of PIH and its renal damage.

[Improvement in affinity of phage antibodies against HBsAg by light chain shuffling]

OBJECTIVE

We had cloned an Fd gene of human antibody against HBsAg previously. The objective of this experiment is to improve the affinity phage antibody by chain-shuffling.

METHODS

Human antibody light chain gene repertoire was generated by RT-PCR from human peripheral blood lymphocyte, and then phage antibody sublibrary was constructed by inserting the repertoire into the phagmid which contained the Fd gene. The matched gene of light chain was selected by biopaning.

RESULTS

After three rounds of selection, eight clones with higher absorbance than that of original clone at 490 nm in ELISA were obtained. DNA sequencing showed three of the five VL genes were kappa type, and the other two were lambda type.

CONCLUSION

The results indicated that the affinity of chain shuffled phage antibodies(phab) were improved. The specificity of the selected phab was also confirmed.

In vitro transcription assay with the purified 40kDa NF1-like protein binding to the rat p53 promoter

The rat p53 promoter has several potential transcription factor-recognition motifs. They include NF1-like, bHLH family, and AP1-like proteins binding sites. The binding protein to NF1-like motif was previously identified. The protein has about 40kDa of molecular mass, which is smaller than that of NF1. Anti-NF1 polyclonal antibody does not recognize the protein. In this study, we isolated the 40kDa protein by sequence-specific DNA affinity chromatography. The isolated protein was assayed by DNase I footprinting analysis. To determine the transactivation effect of the protein, in vitro transcription with the purified 40kDa protein was carried out. After the addition of the purified 40kDa protein into the transcription reaction mixture, the transcription level of the p53 promoter was increased. This suggests that the 40 kDa NF1-like protein is a transcription activator for the rat p53 gene.

Crystal structure of intact elongation factor EF-Tu from Escherichia coli in GDP conformation at 2.05 A resolution

The crystal structure of intact elongation factor Tu (EF-Tu) from Escherichia coli in GDP-bound conformation has been determined using a combination of multiple isomorphous replacement (MIR) and multiwavelength anomalous diffraction (MAD) methods. The current atomic model has been refined to a crystallographic R factor of 20.3 % and free R-factor of 26.8 % in the resolution range of 10-2.05 A. The protein consists of three domains: domain 1 has an alpha/beta structure; while domain 2 and domain 3 are beta-barrel structures. Although the global fold of the current model is similar to those of published structures, the secondary structural assignment has been improved due to the high quality of the current model. The switch I region (residues 40-62) is well ordered in this structure. Comparison with the structure of EF-Tu in GDP-bound form from Thermus aquaticus shows that although the individual domain structures are similar in these two structures, the orientation of domains changes significantly. Interactions between domains 1 and 3 in our E. coli EF-Tu-GDP complex are quite different from those of EF-Tu with bound GTP from T. aquaticus, due to the domain rearrangement upon GTP binding. The binding sites of the Mg2+ and guanine nucleotide are revealed in detail. Two water molecules that co-ordinate the Mg2+ have been identified to be well conserved in the GDP and GTP-bound forms of EF-Tu structures, as well as in the structure of Ras p21 with bound GDP. Comparisons of the Mg2+ binding site with other guanine nucleotide binding proteins in GDP-bound forms show that the Mg2+ co-ordination patterns are well preserved among these structures.

Decoupling of nucleotide- and microtubule-binding sites in a kinesin mutant

Molecular motors require ATP to move along microtubules or actin filaments. To understand how molecular motors function, it is crucial to know how binding of the motor to its filamentous track stimulates the hydrolysis of ATP by the motor, enabling it to move along the filament. A mechanism for the enhanced ATP hydrolysis has not been elucidated, but it is generally accepted that conformational changes in the motor proteins occur when they bind to microtubules or actin filaments, facilitating the release of ADP. Here we report that a mutation in the motor domain of the microtubule motor proteins Kar3 and Ncd uncouples nucleotide- and microtubule-binding by the proteins, preventing activation of the motor ATPase by microtubules. Unlike the wild-type motors, the mutants bind tightly to both ADP and microtubules, indicating that interactions between the nucleotide- and microtubule-binding sites are blocked. The region of the motor that includes the mutated amino acid could transmit or undergo a conformational change required to convert the motor ATPase into a microtubule-stimulated state.

[Investigation of the Zeta reference values by Chinese-built Zetafuge and preliminary application]

We determined the Zeta sedimentation ratio (ZSR) for 326 normal subjects and 106 inpatients by Chinese-built Zetafuge. The mean ZSR for normal subjces was 52.5 +/- 5.05% and that for inpatients 68.52 +/- 5.54% (P < 0.001). ZSR can be determined by using directly the blood sample with the anticoagulant EDTA-K2; the determination is faster and requires less volume of blood sample; it is not affected by anemia and need not be corrected for age and sex. The results of ZSR are expressed in a new unit, %, not in mm/h. The reference value we established is: < or = 62%. We also discussed the problem of reproducibility, the speed of centrifuge, the height of blood, and compared this method with the westergren method. The agreement between the two methods is 86.6%.