Exploring the impact of intensified multiple session tDCS over the left DLPFC on brain function in MCI: a randomized control trial

Transcranial direct current stimulation combined with cognitive training (tDCS-cog) represents a promising approach to combat cognitive decline among healthy older adults and patients with mild cognitive impairment (MCI). In this 5-day-long double-blinded randomized trial, we investigated the impact of intensified tDCS-cog protocol involving two trains of stimulation per day on working memory (WM) enhancement in 35 amnestic and multidomain amnestic MCI patients. Specifically, we focused to improve WM tasks relying on top-down attentional control and hypothesized that intensified tDCS would enhance performance of visual object matching task (VOMT) immediately after the stimulation regimen and at a 1-month follow-up. Secondarily, we explored whether the stimulation would augment online visual working memory training. Using fMRI, we aimed to elucidate the neural mechanisms underlying the intervention effects by analyzing BOLD activations during VOMT. Our main finding revealed no superior after-effects of tDCS-cog over the sham on VOMT among individuals with MCI as indicated by insignificant immediate and long-lasting after-effects. Additionally, the tDCS-cog did not enhance online training as predicted. The fMRI analysis revealed brain activity alterations in right insula that may be linked to tDCS-cog intervention. In the study we discuss the insignificant behavioral results in the context of the current evidence in tDCS parameter space and opening the discussion of possible interference between trained cognitive tasks.

Roles of conserved ectodomain cysteines of the rat P2X4 purinoreceptor in agonist binding and channel gating

Mammalian P2X receptors contain 10 conserved cysteine residues in their ectodomains, which form five disulfide bonds (SS1-5). Here, we analyzed the relevance of these disulfide pairs in rat P2X4 receptor function by replacing one or both cysteines with alanine or threonine, expressing receptors in HEK293 cells and studying their responsiveness to ATP in the absence and presence of ivermectin, an allostenic modulator of these channels. Response to ATP was not altered when both cysteines forming the SS3 bond (C132-C159) were replaced with threonines. Replacement of SS1 (C116-C165), SS2 (C126-C149) and SS4 (C217-C227), but not SS5 (C261-C270), cysteine pairs with threonines resulted in decreased sensitivity to ATP and faster deactivation times. The maximum current amplitude was reduced in SS2, SS4 and SS5 double mutants and could be partially rescued by ivermectin in SS2 and SS5 double mutants. This response pattern was also observed in numerous single residue mutants, but receptor function was not affected when the 217 cysteine was replaced with threonine or arginine or when the 261 cysteine was replaced with alanine. These results suggest that the SS1, SS2 and SS4 bonds contribute substantially to the structure of the ligand binding pocket, while the SS5 bond located towards the transmembrane domain contributes to receptor gating.

Molecular structure of purinergic P2X receptors and their expression in the hypothalamus and pituitary

Purinergic P2X receptors represent a novel structural type of ligand-gated ion channels activated by extracellular ATP. So far, seven P2X receptor subunits have been found in excitable as well as non-excitable tissues. Little is known about their structure, mechanism of channel opening, localization, and role in the central nervous system. The aim of this work is to summarize recent investigations and describe our contribution to elucidating the structure of the ATP binding site and transmembrane domains of the P2X receptor, we also discuss the expression and physiological roles played by the ATP and P2X receptors in the anterior pituitary and hypothalamus.

[Familial haemophagocytic lymphohistiocytosis caused by perforin deficit can be successfully treated by haematopoietic stem cell transplantation--the first diagnosed case in the Czech Republic]

Familial haemophagocytic lymphohistiocytosis (FHL) is an inherited disorder characterized by an impaired cytotoxicity of T lymphocytes and NK cells typically manifesting within first few months after birth. If not treated adequately, it is inevitably fatal within several months. The incidence in Caucasians has been estimated to 1: 50 000 births. Haematopoietic stem cell transplantation represents the only curative treatment for FHL. Recently, several genetic defects underlying molecular defects in FHL have been identified. In approximately 30% of patients FHL is caused by mutations in PRF1 gene coding for perforin. Further 30% of patients were found to have mutations in UNC13D coding for hMunc13-4 protein. Very recent report has identified another cause of FHL, mutations in STX11 gene on chromosome 6, coding for syntaxin 11. Absence of any of those proteins severely impairs the process of exocytosis of cytotoxic granules. We describe patient with clinical symptoms of FHL. Immunological and molecular biology methods led to the identification of perforin mutation as a cause of the disease. Patient received an allogeneic SCT from HLA-matched unrelated donor. SCT was followed by rapid normalization of clinical symptoms and laboratory findings. In patient described in this study, FHL manifested with typical clinical and laboratory symptoms. Adequate immunosuppressive treatment and subsequent SCT led to the sustained remission of FHL and correction of molecular defect. This is the first case of FHL in Czech Republic where perforin mutation was identified as a molecular cause both at cellular and molecular level.

Thermal, cardiac and adrenergic responses to repeated local cooling

The aim of this study was to ascertain whether repeated local cooling induces the same or different adaptational responses as repeated whole body cooling. Repeated cooling of the legs (immersion into 12 degrees C water up to the knees for 30 min, 20 times during 4 weeks = local cold adaptation - LCA) attenuated the initial increase in heart rate and blood pressure currently observed in control subjects immersed in cold water up to the knees. After LCA the initial skin temperature decrease tended to be lower, indicating reduced vasoconstriction. Heart rate and systolic blood pressure appeared to be generally lower during rest and during the time course of cooling in LCA humans, when compared to controls. All these changes seem to indicate attenuation of the sympathetic tone. In contrast, the sustained skin temperature in different areas of the body (finger, palm, forearm, thigh, chest) appeared to be generally lower in LCA subjects than in controls (except for temperatures on the forehead). Plasma levels of catecholamines (measured 20 and 40 min after the onset of cooling) were also not influenced by local cold adaptation. Locally cold adapted subjects, when exposed to whole body cold water immersion test, showed no change in the threshold temperature for induction of cold thermogenesis. This indicates that the hypothermic type of cold adaptation, typically occurring after systemic cold adaptation, does not appear after local cold adaptation of the intensity used. It is concluded that in humans the cold adaptation due to repeated local cooling of legs induces different physiological changes than systemic cold adaptation.

[Consolidation of therapy of acute myeloid leukemia with the AML-BFM 93 protocol in children in the Czech Republic]

BACKGROUND

Acute myeloid leukemia (AML) in children is rare. Although more resistant to chemotherapy than acute lymphoblastic leukemia, its responsiveness and survival rates have considerably improved during the last 15 years by virtue of intensification of chemotherapy and due to the better supportive care. Relapses still remain the main cause of treatment failure. Management of children with AML was unified in the Czech Republic in 1993 according to AML-BFM 93 Study protocol.

METHODS AND RESULTS

Treatment results were evaluated in 61 patients, of whom 45 (73.8%) achieved complete remission. Five-year event-free-survival (EFS) was found in 42.3%, and overall survival was 45.3%. Prognosis of the standard-risk patients was significantly better than in the high-risk group (EFS 62.5% vs. 29.7%, p = 0.03). The most important prognostic factor was the early treatment response. Compared to chemotherapy, allogeneic stem-cell transplantation did not significantly improve the outcome of high-risk patients.

CONCLUSIONS

Treatment results of children with AML in the Czech Republic are comparable to those achieved by leading leukemia study groups in the world. The aim of the next study is to increase the complete-remission rate by reducing early deaths.

[Improved results in children with acute lymphoblastic leukemia treated with the ALL-BFM 90 protocol in the Czech Republic]

BACKGROUND

Prognosis of children with acute lymphoblastic leukaemia (ALL)--the most common cancer in childhood, has improved remarkably over the last 40 years. The authors report the treatment outcome in children with ALL cured according to ALL-BFM 90 Study protocol in the Czech Republic during the first half of nineties.

METHODS AND RESULTS

Children aged 0-18 years were included into the study in 10 centers between 1990 to 1996. Patients were classified into standard-risk (SR), medium-risk (MR) and high-risk (HR) group according to initial leukaemic burden, early treatment response, and genotype of leukaemia. Duration of the chemotherapy was two years. Treatment results were evaluated in 352 children. With a median follow-up of 7.3 years, event-free-survival (EFS) was 71.3% and overall survival 76.4%. EFS was 80.3%, 74% and 28.2% in SR, MR and HR group, respectively. Relapse was diagnosed in 17.8% of the patients.

CONCLUSIONS

The treatment outcome of children with ALL improved significantly (p = 0.0045) compared to the previous study ALL-BFM 83 (EFS 62%). These results are comparable to those achieved by leading leukaemia study groups in the world.

Real-time quantitative PCR detection of WT1 gene expression in children with AML: prognostic significance, correlation with disease status and residual disease detection by flow cytometry

The clinical significance of WT1 gene expression at diagnosis and during therapy of AML has not yet been resolved. We analysed WT1 expression at presentation in an unselected group of 47 childhood AML patients using real-time quantitative reverse-transcription PCR. We also showed that within the first 30 h following aspiration RQ-RT-PCR results were not influenced by transportation time. We observed lower levels of WT1 transcript in AML M5 (P = 0.0015); no association was found between expression levels and sex, initial leukocyte count and karyotype-based prognostic groups. There was significant correlation between very low WT1 expression at presentation and excellent outcome (EFS P = 0.0014). Combined analysis of WT1 levels, three-colour flow cytometry residual disease detection and the course of the disease in 222 samples from 28 children with AML showed remarkable correlation. Fourteen patients expressed high WT1 levels at presentation. In eight of them, who suffered relapse or did not reach complete remission, dynamics of WT1 levels clearly correlated with the disease status and residual disease by flow cytometry. We conclude that very low WT1 levels at presentation represent a good prognostic factor and that RQ-RT-PCR-based analysis of WT1 expression is a promising and rapid approach for monitoring of MRD in approximately half of paediatric AML patients.

[Allogenic transplantation of hematopoietic stem cells in the treatment of children with high-risk acute leukemia]

BACKGROUND

Most children with acute lymphoblastic leukemia (ALL) and increasing number of children with acute myelogenous leukemia (AML) are currently cured with conventional chemotherapy. Despite of this success there is a subset of patients with high-risk features at diagnosis who are predisposed to a very high risk of relapse. Relapse of AML and early bone marrow relapse of ALL can not be cured by conventional chemotherapy. Allogeneic hematopoietic stem cell transplantation (HSCT) is therapeutic option in these children with very high-risk acute leukemia.

METHODS AND RESULTS

Between XI/1989-XII/1996 33 children with acute leukemia (ALL: 22, AML: 11) underwent an allogeneic HSCT from HLA identical related donors (HLA-identical sibling: 30, twin: 1, other HLA-identical relative: 2) at the 2nd Dept. of Pediatrics, University Hospital Motol. Median age of our group was 9 years (1.5-19 y.), boys (n = 23) clearly dominated over the girls (n = 10). The resource of stem cells was bone marrow in 31 children, bone marrow and peripheral blood progenitor cells (PBPC) and PBPC in one child respectively. Myeloablative conditioning regimen varied, consisting of total body irradiation and chemotherapy in 21 children and chemotherapy in 12 children. HSCT was performed in first complete remission of acute leukemia in 9 children (AML: 7, ALL: 2), in second remission in 14 children (AML: 2, ALL: 12), in third remission in 4 children (ALL: 4). Six children underwent HSCT in first partial remission (n = 1) and in second (n = 4) or third (n = 1) chemoresistant relapse. Seven (21%) children died due to post-transplant complications. Nine (28%) children suffered from clinically significant acute graft-versus-host reaction (GVH) and 15% (4/27) children who survived 100 days post-transplant suffered from chronic GVH disease. Relapse of leukemia was diagnosed in 39% (12/31) children. Fourteen (42%) children are alive and well in continuous remission with median follow-up 42 months.

CONCLUSIONS

Allogeneic HSCT can cure children with very high-risk acute leukemia in the situations where conventional chemotherapy fails. Relapse of leukemia and GVH reaction are most important causes of post-transplant morbidity and mortality.

[Successful transplantation of fetal blood in a boy with leukocyte integrin deficiency syndrome]

The authors describe the first successful case of transplantation of haematopoietic stem cells in a patient with severe congenital immunodeficiency-the syndrome of deficiency of leukocytary integrins (LAD), leukocyte adhesion deficiency) in the Czech Republic and, at the same time, the first successful transplantation of umbilical blood in this disease in the world. The six-year boy was completely cured by the transplantation of haematopoietic stem cells contained in umbilical blood sampled during delivery of his healthy brother with identical HLA system. The pretransplantation myeloablative preparation was performed by a combination of busulfan, cyclophosphamide and etoposide. The relatively uncomplicated posttransplantation course was secured by preventive administration of antibiotics and immunoglobulins. The reattachment of the stem cells, estimated from the peripheral blood picture, occurred 25 days after the transplantation, the success of the intervention was confirmed by reaching physiological values of originally null expression of integrins on leukocytes of the patient 30 days after the transplantation. The transplantation of umbilical blood is a very promising therapeutic method especially in children with leukemia, congenital severe immunodeficiencies o inborn errors of metabolism.

Successful HLA-identical sibling cord blood transplantation in a 6-year-old boy with leukocyte adhesion deficiency syndrome

A 6-year-old boy with the severe form of the leukocyte adhesion deficiency syndrome (LAD) received a transplant of cord blood (CBT) from his HLA-identical brother. The donor was proved healthy by successful prenatal diagnosis. CBT was performed after conditioning with etoposide, busulfan and cyclophosphamide. After hematopoietic recovery complete chimerism was proved as well as the normal expression of CD11x/CD18 complex on circulating leukocytes. The only post-transplant complication was a mild pneumonitis resolving on the corticosteroid therapy. Thirteen months after CBT the boy is in good health and shows no signs of immunodeficiency. As far as we know this is the first report of successful CBT in a patient with LAD syndrome.

[Allogenic transplantation of bone marrow in childhood]

BACKGROUND

Bone marrow transplantation has become the therapeutic method in some forms of malignant haemotopoietic diseases, malignant tumours, inborn errors of metabolism and immunodeficiency states. The objective of the presented work is the analysis of 40 allogenic bone marrow transplantations in children made in 1989-1994.

METHODS AND RESULTS

Bone marrow transplantation was made in 40 children (26 boys and 14 girls), mean age 10.5 years (range 1.5-17.5 years). Indications were acute lymphoblastic leukaemia in 11, acute myeloid leukaemia in 10, chronic myeloid leukaemia in 6, myelodysplastic syndrome in 2, aplastic anaemia and Fanconi's anaemia in 7, non-Hodgkin lymphoma in 2 and inborn errors in 2 children. The donor was in 33 patients in HLA identical sibling and in seven instances a monozygotic twin, HLA non-identical sibling or relative or unrelated matched donor. Bone marrow engraftment was achieved in 35 (87.5%) patients, in one instance the bone marrow was rejected (2.5%) and in four patients (10%) early death occurred before the bone marrow engraftment. On Aug. 15, 1995 20 patients (50%) survived, a relapse developed in 7 (17.5%) and 13 patients died in conjunction with the transplantation (32.5%). The most frequent cause of death were infectious complications (9 children) either in conjunction with the development of graft versus host reaction (6x) or without signs of this reaction (3x). As a prophylaxis of graft versus host disease 24x Cyclosporine A with corticosteroids was used, 16x with methotrexate. A chronic graft versus host disease developed in 6 of 28 children surviving 100 days after transplantation. The greatest problem are infectious (bacterial and mycotic) complications in the phase of bone marrow aplasia before engraftment of the transplanted bone marrow or in conjunction with a graft versus host reaction which cannot be completely avoided by preventive measures.

CONCLUSIONS

Bone marrow transplantation is also in children an effective therapeutic method of some forms of malignant haematopoietic diseases, malignant tumours and immunodeficiency states. The correct indication, suitable donor, preventive measures against the graft versus host reaction and protection against infectious complications are essential for the success of this pretentious treatment.