Deterministic synthesis of Cu9S5 flakes assisted by single-layer graphene arrays.

The employment of two-dimensional materials, as growth substrates or buffer layers, enables the epitaxial growth of layered materials with different crystalline symmetries with a preferential crystalline orientation and the synthesis of heterostructures with a large lattice constant mismatch. In this work, we employ single crystalline graphene to modify the sulfurization dynamics of copper foil for the deterministic synthesis of large-area Cu9S5 crystals. Molecular dynamics simulations using the Reax force-field are used to mimic the sulfurization process of a series of different atomistic systems specifically built to understand the role of graphene during the sulphur atom attack over the Cu(111) surface. Cu9S5 flakes show a flat morphology with an average lateral size of hundreds of micrometers. Cu9S5 presents a direct band-gap of 2.5 eV evaluated with light absorption and light emission spectroscopies. Electrical characterization shows that the Cu9S5 crystals present high p-type doping with a hole mobility of 2 cm2 V-1 s-1.

Cognitive reserve as a useful variable to address robotic or conventional upper limb rehabilitation treatment after stroke: a multicentre study of the Fondazione Don Carlo Gnocchi.

BACKGROUND AND PURPOSE: Rehabilitation plays a central role in stroke recovery. Besides conventional therapy, technological treatments have become available. The effectiveness and appropriateness of technological rehabilitation are not yet well defined; hence, research focused on different variables impacting recovery is needed. Results from the literature identified cognitive reserve (CR) as a variable impacting on the cognitive outcome. In this paper, the aim was to evaluate whether CR influences the motor outcome in patients after stroke treated with conventional or robotic therapy and whether it may influence one treatment rather than another. METHODS: Seventy-five stroke patients were enrolled in five Italian neurological rehabilitation centres. Patients were assigned either to a robotic group, rehabilitation by means of robotic devices, or to a conventional group, where a traditional approach was used. Patients were evaluated at baseline and after rehabilitation treatment of 6 weeks through the Action Research Arm Test (ARAT), the Motricity Index (MI) and the Barthel Index (BI). CR was assessed at baseline using the Cognitive Reserve Index (CRI) questionnaire. RESULTS: Considering all patients, a weak correlation was found between the CRI related to leisure time and MI evolution (r = 0.276; P = 0.02). Amongst the patients who performed a robotic rehabilitation, a moderate correlation emerged between the CRI related to working activities and MI evolution (r = 0.422; P = 0.02). CONCLUSIONS: Our results suggest that CR may influence the motor outcome. For each patient, CR and its subcategories should be considered in the choice between conventional and robotic treatment.

Neurocognitive therapeutic exercise improves pain and function in patients with shoulder impingement syndrome: a single-blind randomized controlled clinical trial.

BACKGROUND: Traditional rehabilitation improves pain and function in patients with shoulder impingement syndrome. Neurocognitive rehabilitation has shown to be highly effective after surgical reconstruction of the anterior cruciate ligament. However, its effects in patients with shoulder impingement syndrome have not yet been established. AIM: The aim of the study was to compare the effects of neurocognitive therapeutic exercise, based on proprioception and neuromuscular control, on pain and function in comparison to traditional therapeutic exercise in patients with shoulder impingement syndrome. DESIGN: Single-blind randomized, non-inferiority clinical trial. SETTING: Outpatient clinic of Geriatrics and Physiatrics, University Hospital. POPULATION: Forty-eight patients with shoulder impingement syndrome (Neer stage I) and pain lasting for at least three months. METHODS: Participants were randomly allocated (1:1) to either neurocognitive therapeutic exercise or traditional therapeutic exercise. Both treatments were provided one-hour session, three times a week for five weeks. The primary outcome measure was the short form of the Disability of the Arm, Shoulder and Hand Questionnaire (Quick-DASH questionnaire) for the assessment of physical ability and symptoms of the upper extremity. SECONDARY OUTCOME MEASURES: Constant-Murley shoulder outcome score for the determination of range of motion, pain and strength; American Shoulder and Elbow Surgeons Society standardized shoulder assessment form for the evaluation of physical ability in daily-living tasks; a visual analogue scale for pain assessment at rest and during movements; Likert score for the estimation of participant satisfaction. ENDPOINTS: before treatment, end of treatment, 12 and 24 weeks after the completion of each intervention for all outcome measures, except for the Likert score that was evaluated only at the end of treatment. FOLLOW-UP: 24 weeks. RESULTS: At the end of treatment and at follow-up, both treatment groups experienced improvements in all outcomes measures relative to baseline values, except for the visual analogue scale at rest that was unaffected by traditional therapeutic exercise. For all outcome measures, changes over time were greater in the neurocognitive therapeutic exercise group relative to the traditional therapeutic exercise group. The level of satisfaction with treatment was higher for participants in the neurocognitive therapeutic exercise group. CONCLUSION: Neurocognitive rehabilitation is effective in reducing pain and improving function in patients with shoulder impingement syndrome, with benefits maintained for at least 24 weeks. CLINICAL REHABILITATION IMPACT: skills and function of the shoulder can greatly benefit from neurocognitive rehabilitation.

Differences in survivin location and Bcl-2 expression in CD30+ lymphoproliferative disorders of the skin compared with systemic anaplastic large cell lymphomas: an immunohistochemical study.

BACKGROUND: Cutaneous CD30+ lymphoproliferative disorders (LPDs) are a spectrum of disease associated with a favourable prognosis. Systemic anaplastic large cell lymphoma (ALCL), although morphologically and phenotypically similar, differs in clinical presentation and has a less favourable biological behaviour. Dysregulation of apoptosis, the process regulating cell population by programmed death, can explain the differences among these disorders. OBJECTIVES: We investigated the expression of two inhibitors of apoptosis, survivin and Bcl-2 protein, in serial skin lesion samples from CD30+ LPDs compared with systemic ALCL. METHODS: Immunohistochemical analysis with antibodies against anaplastic lymphoma kinase (ALK)-1 protein, survivin and Bcl-2 protein was performed in 10 cutaneous CD30+ LPDs (five lymphomatoid papulosis, five ALCL) and 18 systemic ALCLs. Reverse transcription-polymerase chain reaction studies for ALK and ALK/nucleophosmin were also performed. RESULTS: Cutaneous CD30+ LPDs shared a heterogeneous expression of cytoplasmic survivin with all systemic ALCLs, and of Bcl-2 with systemic ALK- ALCLs; however, they differ from systemic ALK- ALCLs because they lack nuclear survivin (P = 0.045), and from systemic ALK+ ALCLs by a higher expression of Bcl-2 (P = 0.045) and a lack of ALK-1. Overall, coexpression of Bcl-2 and nuclear survivin in CD30+ LPDs was associated with a less favourable disease survival. CONCLUSIONS: The different patterns of expression of Bcl-2 and survivin in CD30+ LPDs might have an impact on their different biological and clinical behaviour. Moreover, nuclear localization of survivin, similarly to ALK, may be a useful marker for predicting a systemic form of ALCL with cutaneous presentation.

Declining levels of rescued lymphoproliferative response to human cytomegalovirus (HCMV) in AIDS patients with or without HCMV disease following long-term HAART.

OBJECTIVE: To investigate the lymphoproliferative response (LPR) to human cytomegalovirus (HCMV) in two groups of AIDS patients undergoing long-term highly active antiretroviral therapy (HAART): group 1 ( n = 22) with nadir CD4(+) cell count <50/microl and no HCMV disease; group 2 ( n = 16) with <50/microl CD4(+) T-cell count and HCMV disease. All patients had previously undergone antiretroviral monotherapy or dual therapy before initiating HAART. STUDY DESIGN AND METHODS: The two groups of patients were tested prospectively for CD4(+) T cell count, HIV RNA load, HCMV viremia, and LPR to HCMV at baseline, and then after 3 and 4 years of HAART. A control group of 13 recently diagnosed treatment-naive AIDS patients with CD4(+) T-cell counts <100/microl was also investigated. RESULTS: No LPR to HCMV was found in any of the treatment-naive patients nor in any patient of the two groups examined at baseline, when HCMV viremia was 13.6% in the patient group without disease and 87.5% in the group with disease ( p <.0001). After 3 years of HAART, the frequency of patients who recovered an LPR to HCMV was not significantly different (81.8% in the group without HCMV disease, and 68.7% in the group with HCMV disease), whereas, compared with baseline, the HIV load decreased and the CD4(+) T-cell count increased significantly and to a comparable extent in the two groups of patients. In addition, the frequency of patients with HCMV viremia, although reduced, became comparable in both groups. After 4 years of HAART, the frequency of responders to HCMV without and with HCMV disease dropped to comparable levels (50.0 vs. 56.3%, respectively) in association with high median CD4(+) T-cell counts and low median HIV RNA plasma levels. In parallel, the frequency of patients with HCMV viremia did not change significantly. In addition, after between 3 and 4 years of HAART, although the frequency of stable responders and nonresponders remained unchanged (50%) in both groups, most of the remaining patients showed declining levels of responsiveness to HCMV. Although some patients from both groups were found to have CD4(+) T-cell counts >150/microl in the absence of LPR to HCMV, thus suggesting dissociation of specific and nonspecific immune reconstitution, a significant correlation was found between CD4(+) T-cell count and LPR to HCMV (r = 0.44; p <.001). From a clinical standpoint, anti-HCMV therapy could be safely discontinued in 8 patients with HCMV retinitis showing CD4(+) T-cell counts >150/microl, recovery of HCMV LPR, and no HCMV viremia. CONCLUSIONS: Declining levels of the previously recovered LPR to HCMV are often observed after long-term HAART. However, because the role of LPR in the evolution of HCMV infection and disease during HAART remains to be defined, the clinical impact of the declining LPR to HCMV must still be clarified in long-term prospective studies.

Comparative analysis of human cytomegalovirus-specific CD4(+) T-cell frequency and lymphoproliferative response in human immunodeficiency virus-positive patients.

Evaluation of human cytomegalovirus (HCMV)-specific T-helper immunity could contribute in optimizing anti-HCMV therapy in human immunodeficiency virus (HIV)-infected patients. Testin the lymphoproliferative response (LPR) is the standard technique used to evaluate T-helper response, but its use in the routine diagnostic laboratory setting can be problematic. The most promising new alternative technique is the determination of HCMV-specific CD4(+) T-cell frequency by flow cytometry detection of intracellular cytokine production after short-term antigen-specific activation of peripheral blood mononuclear cells. HCMV-specific LPR and CD4(+) T-cell frequency were compared in a group of 78 blood samples from 65 HIV-infected patients. The results showed concordance in 80.7% of samples. In addition, comparative analysis of sequential blood samples from 13 HIV-infected patients showed that while in about half of patients the T-helper HCMV-specific immune response remained stable during highly active antiretroviral therapy (HAART), in the other half declining levels of the HCMV-specific CD4(+)-mediated immune response were determined by either one or both assays. In conclusion, our data suggest that the determination of HCMV-specific CD4(+) T-cell frequency can be considered a valuable alternative to the LPR test for the detection of HCMV-specific T-helper response in HIV-infected patients. It could facilitate wider screening of anti-HCMV T-helper activity in HIV-infected patients, with potential benefits for clinicians in deciding strategies of discontinuation or maintenance of anti-HCMV therapy.

Direct analysis of mitochondrial toxicity of antiretroviral drugs.

OBJECTIVES: Mitochondrial toxicity is a serious side-effect of antiretroviral drugs, especially nucleoside reverse transcriptase inhibitors (NRTI). An in vitro assay to predict mitochondrial toxicity of in-use and developmental NRTI would be invaluable. To test the ability of a cytofluorimetric technique to predict the mitochondrial-dependent pancreatic and hepatic toxicity we used didanosine (ddI) alone or in combination with hydroxyurea (HU). METHODS: The technique is based on the ability of the lipophilic cation JC-1 to enter selectively into mitochondria and change its colour as the membrane potential changes due to toxicity. Mitochondrial toxicity by HU and ddI was evaluated in pancreatic and hepatic human cell lines. The results were expressed as mitochondrial toxicity index (MTI), ranging from 0 to 100: the negative control was 0, and 100 indicating maximal toxicity. RESULTS: Dose-dependent pancreatic toxicity of ddI was evident after 14 days of culture (MTI 34 +/- 4 at 100 microM, 10 +/- 4 at 10 microM, 2 +/- 3 at 1 microM ddI). HU alone was not toxic (MTI 7 +/- 10 at 100 microM, 2 +/- 2 at 50 microM and 2 +/- 4 at 10 microM HU); however, HU increased the toxicity of high, but not low, concentrations of ddI. For example, the MTI of 10 microM ddI plus 50 microM HU was 54 +/- 9. Negligible mitochondrial toxicity was observed in the hepatic cell line exposed to ddI alone or in combination with HU. CONCLUSIONS: This in vitro assay might have in vivo relevance. First, ddI-related pancreatitis is dose dependent, and is reported more frequently than hepatic failure, consistent with our in vitro results. Second, patients who developed pancreatitis during randomized, controlled trials were treated with HU in combination with 400 mg ddI once daily (high peak concentration of ddI in the blood). In contrast, no pancreatitis was observed when HU was combined with 200 mg ddI twice daily (low peak concentration of ddI). These in vivo results are consistent with our in vitro observation that HU increases pancreatic cell toxicity in the presence of high concentrations of ddI. The in vitro assay described here might be used to predict the mitochondrial toxicity of other NRTI, alone or in combination.

Whole-blood calcineurin activity is not predicted by cyclosporine blood concentration in renal transplant recipients.

BACKGROUND: In transplant patients, current cyclosporine (CsA) dose monitoring with classic pharmacokinetics has demonstrated limitations. Evaluation of the activity of calcineurin (CN), the serine-threonine phosphatase enzyme target of CsA, has been proposed as a reliable way to optimize CsA dosing. METHODS: CN activity was measured in whole blood in an attempt to overcome the high variability of results obtained previously with peripheral blood mononuclear cells (PBMCs). We also explored, in vitro, a possible relationship between the CsA concentration and CN inhibition in whole blood. Finally, we assessed whether the CsA blood trough concentration correlates with whole-blood CN activity in kidney transplant recipients (n = 15) on maintenance immunosuppression with CsA. RESULTS: In 14 healthy individuals, less scattered CN activity values were documented in whole blood than in the PBMC fraction. Whole-blood CN activity was higher than the sum of the enzyme activity in each cell blood fraction. After ex vivo incubation of whole blood from healthy subjects (n = 5) with increasing concentrations of CsA (50-1000 microg/L for 1 h), a concentration-dependent inhibition of CN activity was found comparable to that in the PBMC fraction. Moreover, in 15 kidney transplant recipients, no relationship was found between CsA pharmacokinetic parameters and CN activity at time 0. However, a highly significant correlation was found between CN area under the CN activity-time curve, which represents the extent of the CN daily inhibition, and CN activity at time 0 (r = 0.79; P <0.01) and at 12 h postdosing (r = 0.96; P <0.01). CONCLUSIONS: Measuring CN activity in whole-blood samples is a reproducible method. In kidney transplant recipients, CsA trough concentrations do not predict baseline CN activity. Moreover, a single CN activity monitoring at baseline or at time 12 h post-CsA dosing may be a useful surrogate for the inhibition of this enzyme by CsA during 12 h.

Thymic dendritic cells express inducible nitric oxide synthase and generate nitric oxide in response to self- and alloantigens.

Thymocytes maturing in the thymus undergo clonal deletion/apoptosis when they encounter self- or allo-Ags presented by dendritic cells (DCs). How this occurs is a matter of debate, but NO may play a role given its ability of inducing apoptosis of these cells. APC (a mixed population of macrophages (Mphi) and DCs) from rat thymus expressed high levels of inducible NO synthase (iNOS) and produced large amounts of NO in basal conditions whereas iNOS expression and NO production were very low in thymocytes. Analysis by FACS and by double labeling of cytocentrifuged preparations showed that DCs and MPhi both express iNOS within APC. Analysis of a purified preparation of DCs confirmed that these cells express high levels of iNOS and produce large amounts of NO in basal conditions. The capacity of DCs to generate NO was enhanced by exposure to rat albumin, a self-protein, and required a fully expressed process of Ag internalization, processing, and presentation. Peptides derived from portions of class II MHC molecules up-regulate iNOS expression and NO production by DCs as well, both in self and allogeneic combinations, suggesting a role of NO in both self and acquired tolerance. We also found that NO induced apoptosis of rat double-positive thymocytes, the effect being more evident in anti-CD3-stimulated cells. Altogether, the present findings might suggest that DC-derived NO is at least one of the soluble factors regulating events, in the thymus, that follow recognition of self- and allo-Ags.

Expression and production of the long pentraxin PTX3 in rheumatoid arthritis (RA).

PTX3 is a secreted molecule which consists of a C-terminal domain similar to classical pentraxins (e.g. C-reactive protein (CRP)) and of an unrelated N-terminal domain. Unlike the classical pentraxins, the long pentraxin PTX3 is expressed in response to IL-1beta and tumour necrosis factor-alpha (TNF-alpha), but not to IL-6, in various cell types. The present study was designed to investigate the expression of PTX3 in RA. Dissociated RA and osteoarthritis (OA) type B synoviocytes were cultured in the presence and in the absence of inflammatory cytokines. PTX3 mRNA expression in synoviocytes was evaluated by Northern analysis. PTX3 protein levels in synovial cell cultures and synovial fluid were estimated by ELISA, and PTX3 distribution in synovial tissues by immunohistochemical techniques. OA synoviocytes were induced to express high levels of PTX3 mRNA by TNF-alpha, but not by other cytokines including IL-1beta and IL-6. RA synoviocytes, unlike OA synoviocytes, constitutively expressed high levels of PTX3 in the absence of deliberate stimulation. The constitutive expression of PTX3 in RA synoviocytes was not modified by anti-TNF-alpha antibodies, IL-1 receptor antagonist or a combination of the two agents. In contrast, interferon-gamma and transforming growth factor-beta inhibited PTX3 constitutive expression in RA synoviocytes. The joint fluid from RA patients contained higher levels of immunoreactive PTX3 than controls and the synovial tissue contained endothelial cells and synoviocytes positive for PTX3 by immunohistochemistry. In conclusion, PTX3 may play a role in inflammatory circuits of RA, and its relevance as a marker of disease activity deserves further study.

Peripheral donor leukocytes prolong survival of rat renal allografts.

BACKGROUND: The development of strategies to enhance the survival of transplanted organs and to potentially lower or even discontinue immunosuppressive therapy would represent a significant advancement in post-transplant patient care. METHODS: We studied the effect of pretransplant infusion of donor leukocytes alone or in combination with a short course of cyclosporine on the long-term outcome of a rat model of kidney allograft. RESULTS: A single intravenous infusion of donor peripheral blood leukocytes (100x10(6) cells) from Brown-Norway (BN) rats into major histocompatibility complex (MHC) incompatible Lewis recipients largely failed to prolong kidney allograft viability from the same donor transplanted 60, 40, or 30 days after cell infusion. A short course of cyclosporine (per se, unable to prolong graft survival) was started at the same day of donor leukocyte infusion, but instead was able to prolong the survival of the BN kidney transplant-performed 40 days later-but not of a Wistar Furth (WF) third party, with some animals even developing tolerance. A mixed lymphocyte reaction of host cells from long-term surviving rats to BN stimulator cells was significantly reduced as compared with controls. Donor BN DNA was detected in the peripheral blood of Lewis rats until day 40 after BN leukocyte infusion. Microchimerism persisted (60 to 70 days post-transplant) in most long-term graft recipients. Reducing the time interval between donor leukocyte infusion and subsequent kidney transplant to 10 days still prolonged graft survival. Donor peripheral blood mononuclear cells, but not polymorphonuclear cells, in the leukocyte preparation contributed to prolong kidney allograft survival. CONCLUSIONS: Pretransplant donor leukocyte infusion under the appropriate conditions can tip the immune balance toward improved graft acceptance. This result could be relevant to the achievement of donor-specific tolerance of the graft with the maintenance of an intact response to third-party antigens.

Human immunodeficiency virus-1 (HIV-1)-Tat protein promotes migration of acquired immunodeficiency syndrome-related lymphoma cells and enhances their adhesion to endothelial cells.

Human immunodeficiency virus-1 (HIV-1)-Tat, the transactivating gene product of HIV-1, has been shown to interact with different cell types, inducing gene expression, altering their growth and migratory behavior. In this study we examined whether Tat might affect functions of acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin's lymphoma (NHL), relevant to the in vivo dissemination. Our results show that Tat significantly augmented the motility of the two AIDS-related Burkitt's lymphoma cell lines (AS283 and PA682PB) and AIDS-primary effusion lymphoma cell line (HBL-6-AIDS-PEL). Mutations in RGD or basic domain of Tat (KGE-MBP and LxI-MBP, respectively) sharply reduced migration compared with wild type, suggesting that both domains are required for migration. In contrast, a Tat protein mutation outside the active domains (NH(2)-TAT-GST) did not reduce lymphoma cell migration. The treatment of lymphoma cells with Tat did not influence their adhesion to matrix proteins or to human vascular endothelial cells, but endothelial cells treated with Tat became more adhesive to lymphoma cells. Flow cytometric analysis showed that treatment of endothelial cells with Tat induced the cell surface expression of the adhesion molecules vascular cell adhesion molecule-1 (VCAM-1) and E-selectin and increased the expression of intercellular adhesion molecule-1 (ICAM-1). Only antibodies against VCAM-1 on endothelial cells or against the VLA-4 integrin expressed on AS283 cells inhibited the increment of adhesion, indicating the relevance of this pathway in the adhesion of lymphoma cells to vascular endothelium. In our work, we show for the first time that Tat can enhance the migration of lymphoma cells and their adhesion to endothelial cells, two processes that may contribute to the malignant behavior of NHL in patients with AIDS.

Expression of c-myb and B-myb oncogenes on myelofibrotic marrow fibroblasts.

The term IMF (Idiopathic Myelofibrosis) refers to a primary bone marrow disease in which the normal haematopoietic bone marrow cells are for unknown reasons replaced by connective tissue. The pathogenesis of the disease has not been clarified yet. We have speculated that the increment of proliferation of bone marrow fibroblasts in IMF may be the consequence of the over-expression of some oncogenes, leading or contributing to the fibrosis via a cell amplification. Thus, we investigated the possible role of the c-myb and B-myb genes in IMF and control bone marrow fibroblasts in different culture conditions to evaluate proliferation parameters in the absence or presence of serum. Using the reverse transcriptase polymerase chain reaction technique, we demonstrated that the kinetics of induction was similar for both c-myb and B-myb during the proliferation of normal bone marrow fibroblasts. When compared to normal controls, cultured IMF fibroblasts showed more elevated values of c-myb and B-myb RNA; furthermore, after a 72 hours stimulation with serum, c-myb and B-myb messages remained relatively high in myelofibrotic fibroblasts. Finally, after serum starvation, c-myb and to a lesser extent B-myb RNA levels remained unusually high in IMF fibroblasts, while under the same experimental conditions c-myb and B-myb messages became virtually undetectable in normal bone marrow fibroblasts. To our knowledge this work represents the first description of an abnormal behavior of these genes in IMF fibroblasts.

C-myb, but not B-myb, upregulates type I collagen gene expression in human fibroblasts.

C-myb and B-myb belong to the myb family of transcription factors. We have shown previously that c-myb is deregulated in fibroblasts from systemic sclerosis (scleroderma) patients relative to normal fibroblasts. Scleroderma fibroblasts are known to express elevated levels of collagen genes and transforming growth factor beta is known to be a pro-fibrotic cytokine and to induce transcription of type I collagen genes. We have therefore investigated the role of c-myb and B-myb in the regulation of type I collagen genes in response to transforming growth factor beta in normal human fibroblasts. We show that, in these cells, transforming growth factor beta treatment induces c-myb as well as collagen alpha1(I) and alpha2(I) gene expression, but not B-myb. Furthermore we demonstrate by cotransfection assays that c-myb can upregulate alpha1(I) and alpha2(I) collagen promoters by 6-10-fold whereas B-myb is inactive. The activity of c-myb on both type I collagen promoters requires a functional c-myb DNA binding domain suggesting a direct interaction between c-myb and these promoters. Indeed c-myb is active also on a 500 bp fragment of the alpha2(I) collagen promoter and can bind to this fragment in electrophoretic mobility shift assays. Finally, we show that anti-c-myb anti-sense treatment reduces alpha1(I) and to a lesser extent alpha2(I) collagen gene expression. These data strongly suggest that c-myb, but not B-myb, plays a direct role in the upregulation of type I collagen gene expression in response to transforming growth factor beta.

N1,N12-bis(ethyl)spermine effect on growth of cis-diamminedichloroplatinum(II)-sensitive and -resistant human ovarian-carcinoma cell lines.

The results presented here demonstrate that a cis-diamminedichloroplatinum(II) (DDP)-resistant human ovarian-carcinoma cell line is also cross-resistant to the spermine analogue N1,N12-bis(ethyl)spermine (BESPM). We report that C13* cells, which are approximately 20-fold resistant to DDP, similarly showed 7-fold resistance to BESPM by colony-forming assay with an IC50 value of 24.6 +/- 2 microM vs. 3.4 +/- 0.8 microM of 2008 cells. Resistance appears to be the result of many effects, such as different morphological and functional modifications of mitochondria. Furthermore, although BESPM accumulation was almost identical in sensitive and resistant cells, the intracellular polyamine pool of the 2 cell lines was differentially affected by this polyamine analogue. In fact, when spermidine (SPD) was still detectable in C13* cells, in 2008 cells it was not, and the spermine (SPM) content was always more markedly reduced in sensitive cells than in the resistant variant. The lower polyamine content of 2008 cells could be related to a higher degree of induction of spermidine/ spermine N1-acetyltransferase (SSAT) activity by BESPM in sensitive cells than in their resistant counterpart. Despite the observed cross-resistance, the combination of the 2 drugs resulted in supra-additive and synergistic effects in both cell lines, depending on concentration, as assessed by median-effect analysis of the survival data. The effectiveness of this combination was also confirmed by the increased accumulation of cells in the G2/M phase of the cell cycle in both cell lines. Taken together, these data suggest that BESPM effect on cell growth of DDP-sensitive and DDP-resistant cells involves multiple mechanisms that are differently modulated by the DDP-resistant phenotype.

Phosphopeptides derived from in vitro phosphorylated E. coli RNA polymerase bind to DNA and affect DNA transcription.

E. Coli RNA polymerase was phosphorylated with protein kinase CKII and allowed to bind to pBR322. After digestion of the RNA polymerase-pBR322 complex with proteinase K, the phosphopeptides that remained bound to DNA were extracted and analyzed. These phosphopeptides are able to bind again to DNA and to inhibit transcription.

Modulation of cis-diamminedichloroplatinum (II) accumulation and cytotoxicity by spermine in sensitive and resistant human ovarian carcinoma cells.

The effect of spermine (Sp), a natural polycationic amine, on cisplatin (CDDP) sensitivity and accumulation of a human ovarian CDDP-sensitive cell line (2008) and its resistant variant (C13*) was investigated. Survival was also studied. The C13* cells were approximately 20-fold resistant to CDDP, yet were found to be just as sensitive to Sp as 2008 cells. When Sp was concurrently added with CDDP to the colony-forming assay, the IC50 dose was approximately 3-fold lower than that of CDDP alone. This decrease was the result of a synergistic interaction, as assessed by median effect analysis. The incubation of cells with the approximate IC50 dose of Sp for 1-8 h indicated that this synergism could be due to stimulation of CDDP accumulation, showing maximal uptake after 4 h of Sp exposure. This stimulation may be the result of a modulation of cellular membrane permeability by Sp, as assessed by the accumulation of [3H]mannitol. Exposure to Sp concentrations active on CDDP uptake also significantly increased [3H]mannitol accumulation in both cell lines. The triamine spermidine (Spd) did not significantly affect either the sensitivity of the two cell lines or CDDP and [3H]mannitol accumulation. These results suggest that Sp is a positive modulator of CDDP uptake, and thus of its cytotoxicity, even in resistant cells, where the phenotype is partly due to a CDDP accumulation defect.

Redundant functions of B-Myb and c-Myb in differentiating myeloid cells.

We show in this report that the human myeloid leukemia cell line GFD8 is a useful model to compare the biological function of the structurally related c-Myb and B-Myb proto-oncogenes and to investigate the c-myb domains required for this function. GFD8 cells are dependent for growth on granulocyte-macrophage colony-stimulating factor and differentiate in response to phorbol myristate acetate (PMA). We have stably transfected this cell line with constructs constitutively expressing c-Myb or B-Myb. Deregulated expression of both c-Myb and B-Myb inhibited the differentiation observed in response to PMA and, in particular, the induction of the CD11b and CD11c antigens on the cell surface, and the induction of adherence. Furthermore, c-Myb and B-Myb enhanced expression of CD13 upon PMA treatment. Although deregulated Myb expression did not alter the growth factor dependence of the cells, it led to an increase in G2 relative to G1 arrest in cells induced to differentiate in response to PMA, whereas control vector-transfected cells were blocked mostly in G1. This decrease in G1 block took place despite normal induction of the cyclin-dependent kinase inhibitor protein p21 (CIP1/WAF1). Thus, GFD8 cells stably expressing the human B-Myb protein behaved in a manner indistinguishable from those stably expressing C-Myb for both differentiation and cell cycle parameters. In agreement with these findings and differently from most previous reports, transactivation assays show that B-myb can indeed act as a strong activator of transcription. Finally, we demonstrated that although the DNA-binding domain of c-myb is required for both the differentiation block and the shift in cell cycle after PMA treatment, phosphorylation by casein kinase II and mitogen-activated protein kinase at positions 11 and 12 or 532 of c-myb, respectively, are not. We conclude that c-Myb and B-Myb may activate a common cellular program in the GFD8 cell line involved in both differentiation and cell cycle control.

Tyrosine phosphorylation of band 3 protein in Ca2+/A23187-treated human erythrocytes.

Human erythrocytes were induced to release membrane vesicles by treatment with Ca2+ and ionophore A23187. In addition to the biochemical changes already known to accompany loading of human erythrocytes with Ca2+, the present study reveals that tyrosine phosphorylation of the anion exchanger band 3 protein also occurs. The relationship between tyrosine phosphorylation of band 3 and membrane vesiculation was analysed using quinine (a non-specific inhibitor of the Ca(2+)-activated K+ channel, and the only known inhibitor of Ca(2+)-induced vesiculation) and charybdotoxin, a specific inhibitor of the apamin-insensitive K(+)-channel. Both inhibitors suppressed tyrosine phosphorylation of band 3. In the presence of quinine, membrane vesiculation was also suppressed. In contrast, at the concentration of charybdotoxin required to suppress tyrosine phosphorylation of band 3, membrane vesiculation was only mildly inhibited (16-23% inhibition), suggesting that tyrosine phosphorylation of band 3 is not necessary for membrane vesiculation. Phosphorylation of band 3 was in fact observed when erythrocytes were induced to shrink in a Ca(2+)-independent manner, e.g. by treatment with the K+ ionophore valinomycin or with hypertonic solutions. These observations suggest that band 3 tyrosine phosphorylation occurs when cell volume regulation is required.