Tamoxifen dilates porcine coronary arteries: roles for nitric oxide and ouabain-sensitive mechanisms

BACKGROUND AND PURPOSE

Experiments were designed to determine the mechanism of the relaxation induced by tamoxifen in porcine coronary arteries at the tissue, cellular and molecular levels.

EXPERIMENTAL APPROACH

Porcine left circumflex coronary arteries were isolated and isometric tension was measured. [Ca2+]i in native endothelial cells of intact arteries was determined by a calcium fluorescence imaging technique and eNOS ser1177 phosphorylation was assayed by Western blotting.

KEY RESULTS

Tamoxifen induced an endothelium-dependent relaxation that was antagonized by ICI 182,780 and abolished by NG-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2,4]oxadizolo[4,3-a]quinoxalin-1-one (ODQ). L-Arginine reversed the effect of L-NAME while indomethacin was without effect. Tamoxifen-induced relaxation was attenuated by charybdotoxin (CTX) plus apamin, ouabain or by incubation in a K+ -free solution. Moreover, tamoxifen triggered extracellular Ca2+ -dependent increases in endothelial [Ca2+]i and this effect was abolished by ICI 182,780. Endothelium-independent relaxation to sodium nitroprusside was also inhibited by ouabain or in a K+ -free solution. Furthermore, tamoxifen increased endothelial nitric oxide synthase (eNOS) phosphorylation at Ser-1177 and ICI 182,780 prevented this effect.

CONCLUSIONS AND IMPLICATIONS

The present results suggest that tamoxifen mainly induces endothelium-dependent relaxation and that endothelial nitric oxide (NO) is the primary mediator of this effect. NO-dependent responses may result from elevated [Ca2+]i in endothelial cells; an effect abolished by ICI 182,780. NO activates Na+/K+ -ATPase in vascular smooth muscle, leading to relaxation. These results suggest that tamoxifen is able to modulate eNOS phosphorylation directly.

A novel triple purge strategy for eliminating chronic myelogenous leukemia (CML) cells from autografts

Imatinib-refractory chronic myelogenous leukemia (CML) patients can experience long-term disease-free survival with myeloablative therapy and allogeneic hematopoietic cell transplantation; however, associated complications carry a significant risk of mortality. Transplantation of autologous hematopoietic cells has a reduced risk of complications, but residual tumor cells in the autograft may contribute to relapse. Development of methods for purging tumor cells that do not compromise the engraftment potential of the normal hematopoietic cells in the autograft has been a long-standing goal. Since primitive CML cells differentiate more rapidly in vitro than their normal counterparts and are also preferentially killed by mafosfamide and imatinib, we examined the purging effectiveness on CD34(+) CML cells using a strategy that combines a brief exposure to imatinib (0.5-1.0 microM for 72 h) and then mafosfamide (30-90 microg/ml for 30 min) followed by 2 weeks in culture with cytokines (100 ng/ml each of stem cell factor, granulocyte colony-stimulating factor and thrombopoietin). Treatment with 1.0 microM imatinib, 60 microg/ml mafosfamide and 14 days of culture with cytokines eliminated BCR-ABL(+) cells from chronic phase CML patient aphereses, while preserving normal progenitors. This novel purging strategy may offer a new approach to improving the effectiveness of autologous transplantation in imatinib-refractory CML patients.

Effects of carbon nanotubes and metal catalysts on hydrogen storage in magnesium nanocomposites

This paper reports a study on nanostructured magnesium composites with carbon nanotubes (CNTs) and catalytic transition metals with high H2 adsorption capacity and fast adsorption kinetics at reduced hydrogenation temperatures. Nanostructures in such a composite are shown to be responsible for improvements in both adsorption capacity and kinetics. It is found that the carbon nanotubes significantly increase the hydrogen storage capacity, and the catalytic transition metals (Fe and Ti) greatly improve the kinetics. This could be understood from the enhancement of diffusion by CNTs and decrease in energy barrier of hydrogen dissociation at the magnesium surface.

Increased seizure duration in mice lacking aquaporin-4 water channels

Aquaporins are intrinsic membrane proteins involved in water transport in fluid-transporting tissues. In the brain, aquaporin-4 (AQP4) is expressed widely by glial cells, but its function is unclear. Extensive basic and clinical studies indicate that osmolarity affects seizure susceptibility, and in our previous studies we found that AQP4 -/- mice have an elevated seizure threshold in response to the chemoconvulsant pentylenetetrazol. In this study, we examined the seizure phenotype of AQP4 -/- mice in greater detail using in vivo electroencephalographic recording. AQP4 -/- mice were found to have dramatically longer stimulation-evoked seizures following hippocampal stimulation as well as a higher seizure threshold. These results implicate AQP4 in water and potassium regulation associated with neuronal activity and seizures.

AML-loaded DC generate Th1-type cellular immune responses in vitro

BACKGROUND

The generation of AML-specific T-lymphocyte responses by leukemia-derived DC has been documented by multiple investigators and is being pursued clinically. An obstacle to widespread use of this strategy is that it has not been possible to generate leukemic DC from all patients, and an alternative approach is needed if the majority of leukemia patients are to receive therapeutic vaccination in conjunction with other treatment protocols.

METHODS

In the present study, we generated DC from CD14-selected monocytes isolated from healthy donor PBPC and loaded them with a total cell lysate from AML patient blasts.

RESULTS

Immature in vitro-derived DC exhibited robust phagocytic activity, and mature DC demonstrated high expression of CD80, CD83, CD86 and the chemokine receptor CCR7, important for DC migration to local lymph nodes. Mature, Ag-loaded DC were used as APC for leukemia-specific cytotoxic T-lymphocyte (CTL) induction and demonstrated cytotoxic activity against leukemic targets. CTL lysis was Ag-specific, with killing of both allogeneic leukemic blasts and autologous DC loaded with allogeneic AML lysate. HLA-matched controls were not lysed in our system.

DISCUSSION

These data support further research into the use of this strategy as an alternative approach to leukemia-derived DC vaccination.

Interventions to enhance medication adherence

BACKGROUND

People who are prescribed self-administered medications typically take less than half the prescribed doses. Efforts to assist patients with adherence to medications might improve the benefits of prescribed medications, but also might increase their adverse effects.

OBJECTIVES

To update a review summarizing the results of randomized controlled trials (RCTs) of interventions to help patients follow prescriptions for medications for medical problems, including mental disorders but not addictions.

SEARCH STRATEGY

Computerized searches were updated to September 2004 without language restriction in MEDLINE, EMBASE, CINAHL, The Cochrane Library, International Pharmaceutical Abstracts (IPA), PsycINFO and SOCIOFILE. We also reviewed bibliographies in articles on patient adherence and articles in our personal collections, and contacted authors of original and review articles on the topic.

SELECTION CRITERIA

Articles were selected if they reported an unconfounded RCT of an intervention to improve adherence with prescribed medications, measuring both medication adherence and treatment outcome, with at least 80% follow-up of each group studied and, for long-term treatments, at least six months follow-up for studies with positive initial findings.

DATA COLLECTION AND ANALYSIS

Study design features, interventions and controls, and results were extracted by one reviewer and confirmed by at least one other reviewer. We extracted adherence rates and their measures of variance for all methods of measuring adherence in each study, and all outcome rates and their measures of variance for each study group, as well as levels of statistical significance for differences between study groups, consulting authors and verifying or correcting analyses as needed.

MAIN RESULTS

For short-term treatments, four of nine interventions reported in eight RCTs showed an effect on both adherence and at least one clinical outcome, while one intervention reported in one RCT significantly improved patient compliance, but did not enhance the clinical outcome. For long-term treatments, 26 of 58 interventions reported in 49 RCTs were associated with improvements in adherence, but only 18 interventions led to improvement in at least one treatment outcome. Almost all of the interventions that were effective for long-term care were complex, including combinations of more convenient care, information, reminders, self-monitoring, reinforcement, counseling, family therapy, psychological therapy, crisis intervention, manual telephone follow-up, and supportive care. Even the most effective interventions did not lead to large improvements in adherence and treatment outcomes. Six studies showed that telling patients about adverse effects of treatment did not affect their adherence.

AUTHORS' CONCLUSIONS

Improving short-term adherence is relatively successful with a variety of simple interventions. Current methods of improving adherence for chronic health problems are mostly complex and not very effective, so that the full benefits of treatment cannot be realized. High priority should be given to fundamental and applied research concerning innovations to assist patients to follow medication prescriptions for long-term medical disorders.

Fractal spectral analysis of pre-epileptic seizures in terms of criticality

The analysis of pre-epileptic seizure through EEG (electroencephalography) is an important issue for epilepsy diagnosis. Currently, there exist some methods derived from the dynamics to analyse the pre-epileptic EEG data. It is still necessary to create a novel method to better fit and explain the EEG data for making sense of the seizures' predictability. In this paper, a fractal wavelet-based spectral method is proposed and applied to analyse EEG recordings from rat experiments. Three types of patterns are found from the 12 experiments; moreover three typical cases corresponding to the three types of seizures are sorted out and analysed in detail by using the new method. The results indicate that this method can reveal the characteristic signs of an approaching seizure, which includes the emergence of long-range correlation, the decrease of anti-persistence behaviour with time and the decrease of the fractal dimension. The pre-seizure features and their implications are further discussed in the framework of the theory of criticality. We suggest that an epileptic seizure could be considered as a generalized kind of "critical phenomenon", culminating in a large event that is analogous to a kind of "critical point". We also emphasize that epileptic event emergence is a non-repetitive process, so the critical interpretation meets a certain number of cases.

The membrane-recruitment-and-recycling hypothesis of gastric HCl secretion

In the unstimulated oxyntic (or parietal) cell, the primary pump for gastric HCl secretion, the H+/K+-ATPase, is retained within the cytoplasm in a membranous compartment of tubulovesicles. Neural or hormonal stimulation of acid secretion induces extensive membrane transformations consistent with a fusion and recruitment of tubulovesicles to the apical plasma membrane. The consequent placement of H+/K+-ATPase in parallel with K(+) and Cl(-) channels provides the necessary ionic flow and ATP-driven exchange for net HCl secretion. Current evidence is consistent with a recruitment and recycling of membrane transporters, such as H+/K+-ATPase, through docking/fusion machinery analogous to that in many other systems.

Direct attachment of cell suspensions to high-pressure freezing specimen planchettes

We describe a procedure for high-pressure freezing (HPF) of cultured cells using the HPF aluminium planchettes as a substrate. Cells are either grown directly on planchettes covered with Matrigel or allowed to attach to poly-l-lysine-coated planchettes. This method allows for rapid transfer of the cells into the HPF and minimizes physical and physiological trauma to the cells. Furthermore, the yield of well-frozen cells approaches 100% for every cell type we have tried so far. In this report, we show well-preserved ultrastructure in mitotic and interphase HeLa cells, isolated gastric parietal cells and isolated gastric glands. Immunogold labelling of H+/K+-ATPase is shown in parietal cells of isolated gastric glands embedded in LR White resin. The aluminium planchettes appear to have little effect on cell physiology, as demonstrated by the fact that parietal cells cultured for 24-28 h on the planchettes retain their responsiveness to stimulation with histamine.

A mechanosensitive cation channel in endothelial cells and its role in vasoregulation

Ca2+ is an important intracellular second messenger in signal transduction of endothelial cells. It has long been recognized that a mechanosensitive Ca2+-permeable channel is present in vascular endothelial cells. The activity of this channel may increase intracellular Ca2+ level in endothelial cells. A recent finding is that the activity of this channel may be regulated by cGMP through a protein kinase G-dependent pathway. Inhibition of the channel by cGMP abolishes the Ca2+ influx elicited by flow. Several inhibitors of the cation channel including Gd3+, Ni2+, and SK&F-96365 also inhibit the Ca2+ influx due to flow stimulation. These data suggest that a mechanosensitive cation channel is the primary pathway mediating the flow-induced Ca2+ entry in vascular endothelial cells. Another important finding is that the opening of this mechanosensitive channel by KT5823 leads to endothelium-dependent vascular dilation. Therefore, it appears that this channel may play a crucial role in the regulation of vascular tone.

Effect of 17beta-estradiol exposure on vasorelaxation induced by K(+) channel openers and Ca(2+) channel blockers

17beta-Estradiol has been shown to relax blood vessels partly through inhibition of Ca(2+) channels at supraphysiological concentrations; however, it is unknown whether acute exposure of the isolated artery rings to near physiological concentrations of sex steroid hormones could modulate the ionic channels that are involved in regulation of vascular tone. Brief incubation (20 min) with 17beta-estradiol (1-3 nmol/l) did not alter the relaxant response to three blocking agents of L-type voltage-sensitive Ca(2+) channels, nifedipine, diltiazem and verapamil in either endothelium-intact or endothelium-denuded rat mesenteric artery rings. In contrast, 17beta-estradiol at 3 nmol/l significantly attenuated the relaxation induced by K(+) channel openers, cromakalim and pinacidil in endothelium-denuded rings. Similarly, preincubation with progesterone (3 nmol/l) inhibited pinacidil-induced relaxation with much less effect on cromakalim-induced relaxation. It appears that 17beta-estradiol and progesterone attenuated the cromakalim- and pinacidil-induced relaxation in a different manner. These results suggest that acute exposure to female sex steroid hormones at near physiological levels may reduce the activity of ATP-sensitive K(+) channels in the rat arteries.

The distribution and significance of renal infiltrating cells in patients with diffuse crescentic glomerulonephritis

OBJECTIVE

To study the significance and distribution of renal infiltrating cells, including monocytes (CD68+ cells), proliferative cell nuclear antigen positive cells (PCNA+ cells), CD4+ and CD8+ cells in diffuse crescent glomerulonephritis (DCGN).

METHODS

Fifty-six patients with DCGN were studied, including 10 cases of anti-glomerular basement membrane (GBM)--type I DCGN, 26 immune complex--type II DCGN, and 20 cases of pauci-immune--type III DCGN. Glomerular and interstitial infiltrates of CD68+ and PCNA+ cells, and interstitial infiltrates of CD4+ and CD8+ cells were detected by using four-layer PAP methods.

RESULTS

There was a significant increase of renal infiltrating CD68+, PCNA+, CD4+ and CD8+ cells in patients with DCGN compared with that in normal controls. In patients with type I DCGN, there was a higher number of renal infiltrating CD68+ and PCNA+ cells than that in patients with type II and III DCGN. A glomerular infiltrates of CD68+ and PCNA+ cells correlated with the interstitial infiltrates of CD4+ cells in type I or III DCGN patients. In lupus DCGN patients, the numbers of renal infiltrating CD68+ and PCNA+ cells were similar to vasculitis or type III DCGN patients.

CONCLUSION

These findings demonstrate that the renal infiltrates of CD68+ and PCNA+ cells play an important role in patients with DCGN, that the infiltrates of CD4+ cells correlate with the infiltrates of CD68+ and PCNA+ cells may be an active marker of DCGN, and that cell-mediated immunity may contribute to crescent formation in lupus DCGN patients.

cGMP abolishes agonist-induced [Ca(2+)](i) oscillations in human bladder epithelial cells

Cytosolic calcium oscillations may permit cells to respond to information provided by increases in intracellular Ca(2+) concentration ([Ca(2+)](i) ) while avoiding prolonged exposure to constantly elevated [Ca(2+)](i). In this study, we demonstrated that agonists could induce Ca(2+) oscillations in human bladder epithelial cells. Application of 10 microM acetylcholine or 200 nM bradykinin triggered an initial Ca(2+) transient that was followed by periodic [Ca(2+)](i) oscillations. The oscillations did not depend on extracellular Ca(2+). 8-Bromoguanosine 3',5'-cyclic monophosphate abolished acetylcholine- or bradykinin-induced oscillations. Elevation of cellular cGMP by dipyridamole, an inhibitor of cGMP-specific phosphodiesterase, also terminated the [Ca(2+)](i) oscillations. The inhibitory effect of cGMP could be reversed by KT-5823, a highly specific inhibitor of protein kinase G (PKG), suggesting that the action of cGMP was mediated by PKG. Comparison of the effect of cGMP with that of xestospongin C, an inhibitor of the inositol 1,4,5-trisphosphate (IP(3)) receptor, revealed similarities between the action of cGMP and xestospongin C. Therefore, it is likely that cGMP and PKG may target a signal transduction step(s) linked to IP(3) receptor-mediated Ca(2+) release.

Cyclosporin A treatment for idiopathic membranous nephropathy

OBJECTIVE

To evaluate the efficacy of cyclosporin A (CSA) in the treatment of idiopathic membranous nephropathy (IMN), a prospective controlled clinical study was performed.

METHODS

This study included a group of 30 IMN patients, among them 15 were treated with CSA and 15 with captopril (CAP). The diagnosis of IMN was made with exclusion of secondary forms of membranous nephropathy by extensive clinical and pathological studies. No patients received steroids or cytotoxic agents for six months prior to enrollment. In the CSA group, CSA was given at an initial dosage of 5 mg.kg-1.d-1, gradually tailed off over the first three months and maintained at 2 mg.kg-1.d-1 for 12 months. In the CAP group, CAP was given at a dosage of 37.5 mg/day.

RESULTS

In the first three months, 6 (6/15) complete remissions (CR) and 2 (2/15) partial remissions (PR) were observed in the CSA group while only 2 (2/15) PRs were observed in the CAP group. Before the end of the 15-months, 8 patients in the CSA group experienced CR and 4 patients experienced PR. One CR patient relapsed as the dosage of CSA was reduced, so 7 patients remained in CR at the end of the first 15-months. No additional CR or PR was observed in the CAP group during late follow-up. At the last visit (an average follow-up time of 44 months) in the CSA-group, another 2 CR patients had relapsed and 1 CR patient shifted to PR after stopping the CSA treatment, so 4 CR and 5 PR remained in the CSA group. In the CAP group, 3 spontaneous CRs occurred beyond 1.5 year's follow-up, with 3 CR and 2 PR at the last visit. No difference was found between the averages of the initial and the last serum creatinine levels in either group. No serious adverse effects were found during CSA treatment. Re-biopsy data of three patients responsive to CSA treatment showed that no pathological improvement of glomerular basement membrane was observed, even in cases at remission. Tubulointerstitial fibrosis was found in 1 relapsed CR patient, whose serum creatinine increased above the normal range, but not in the other 2 patients whose serum creatinine remained in the normal range.

CONCLUSIONS

CSA therapy at a dosage of 5 mg.kg-1.d-1 is effective in inducing remission of nephrotic syndrome in adult IMN patients within three months, with a response rate of 80%. A relatively high rate of relapse (50%) was observed within 2 years after the withdrawal of CSA treatment.

Regression and clonally distinct recurrence of human immunodeficiency virus related Burkitt-like lymphoma during antiretroviral therapy

An increased incidence of intermediate to high-grade Non Hodgkin's Lymphoma is found in individuals with AIDS. Although immune function in AIDS patients can be improved through the use of antiretroviral therapy, the contribution of these drugs to lymphoma regression is not known. Here we describe the complete regression and subsequent recurrence of high grade, Burkitt-like lymphoma during antiretroviral therapy in a patient with AIDS. Antiretroviral therapy resulted in diminished viral load and modest improvement in CD4+ T cell counts. Lymphoma regressed initially, but relapsed 3 months later. Tissue taken from the initial and recurrent tumor demonstrated different clonal rearrangements. The recurrent lymphoma did not respond to continued antiretroviral therapy. In Conclusion, antiretroviral therapy may contribute to lymphoma regression in AIDS lymphoma. Clinically recurrent disease may be clonally distinct.

Prediction of enthalpy of alkanes by the use of radial basis function neural networks

A new method for the prediction of enthalpy of alkanes between C6 and C10 from molecular structures has been proposed. Thirty five calculated descriptors were selected for the description of molecular structures. The first four scores of Principle Component Analysis on the calculated descriptors were used as inputs to predict the enthalpy of alkanes. Models relating relationships between molecular structure descriptors and enthalpy of alkanes were constructed by means of radial basis function neural networks. To get the best prediction results, some strategies were also employed to optimise the learning parameters of the radial basis function neural networks. For the test set, a predictive correlation coefficient of R = 0.9913 and root mean squared error of 0.5876 were obtained.

Inhibitory effect of tetrabutylammonium ions on endothelium/nitric oxide-mediated vasorelaxation

Apart from the well-described K+ channel blocking effects in vascular smooth muscle cells, monovalent quaternary ammonium ions may also interact with endothelial cells in the endothelium-intact mammalian arteries. The present study was aimed to examine the effect of tetrabutylammonium ions on endothelium-dependent and -independent relaxation in the rat isolated aortic rings. Pretreatment with tetrabutylammonium concentration dependently reduced the endothelium-dependent relaxation induced by acetylcholine, cyclopiazonic acid and ionomycin. Tetrabutylammonium also inhibited endothelium-independent relaxation induced by hydroxylamine or nitroprusside. Pretreatment of endothelium-denuded rings with tetrabutylammonium did not affect relaxation induced by NS1619 or by diltiazem. In contrast, tetrabutylammonium significantly reduced the pinacidil- or cromakalim-induced relaxation. Tetrabutylammonium also inhibited the acetylcholine- but not nitroprusside-induced increase of tissue content of cyclic GMP in the aortic rings. The present study indicates that tetrabutylammonium ions could inhibit endothelial and exogenous nitric oxide-mediated aortic relaxation while it had no effect on relaxation induced by activation of Ca2+-activated K+ channels (by NS1619) or by inhibition of voltage-gated Ca2+ channels (by diltiazem). The inhibitory effect on pinacidil- and cromakalim-induced relaxation suggests that tetrabutylammonium ions also inhibit ATP-sensitive K+ channels in aortic smooth muscle cells.