Searching for the optimal tDCS target for motor rehabilitation

BACKGROUND

Transcranial direct current stimulation (tDCS) has been investigated over the years due to its short and also long-term effects on cortical excitability and neuroplasticity. Although its mechanisms to improve motor function are not fully understood, this technique has been suggested as an alternative therapeutic method for motor rehabilitation, especially those with motor function deficits. When applied to the primary motor cortex, tDCS has shown to improve motor function in healthy individuals, as well as in patients with neurological disorders. Based on its potential effects on motor recovery, identifying optimal targets for tDCS stimulation is essential to improve knowledge regarding neuromodulation as well as to advance the use of tDCS in clinical motor rehabilitation.

METHODS AND RESULTS

Therefore, this review discusses the existing evidence on the application of four different tDCS montages to promote and enhance motor rehabilitation: (1) anodal ipsilesional and cathodal contralesional primary motor cortex tDCS, (2) combination of central tDCS and peripheral electrical stimulation, (3) prefrontal tDCS montage and (4) cerebellar tDCS stimulation. Although there is a significant amount of data testing primary motor cortex tDCS for motor recovery, other targets and strategies have not been sufficiently tested. This review then presents the potential mechanisms and available evidence of these other tDCS strategies to promote motor recovery.

CONCLUSIONS

In spite of the large amount of data showing that tDCS is a promising adjuvant tool for motor rehabilitation, the diversity of parameters, associated with different characteristics of the clinical populations, has generated studies with heterogeneous methodologies and controversial results. The ideal montage for motor rehabilitation should be based on a patient-tailored approach that takes into account aspects related to the safety of the technique and the quality of the available evidence.

Use of specific PCR primers to identify three important industrial species of Saccharomyces genus: Saccharomyces cerevisiae, Saccharomyces bayanus and Saccharomyces pastorianus

AIM

To develop species-specific primers capable of distinguishing between three important yeast species in alcoholic fermentation: Saccharomyces bayanus, Saccharomyces cerevisiae and Saccharomyces pastorianus.

METHODS AND RESULTS

Two sets of primers with sequences complementary to the HO genes from Saccharomyces sensu stricto species were used. The use of the ScHO primers produced a single amplificon of c. 400 or 300 bp with species S. cerevisiae and S. pastorianus, respectively. The second pair of primers (LgHO) was also constructed, within the HO gene, composed of perfectly conserved sequences common for S. bayanus species, which generate amplicon with 700 bp. No amplification product was observed in the DNA samples from non-Saccharomyces yeasts. Saccharomyces species have also been characterized via electrophoretic karyotyping using pulsed-field gel electrophoresis to demonstrate chromosomal polymorphisms and to determine the evolutionary distances between these species.

CONCLUSIONS

We conclude that our novel species-specific primers could be used to rapidly and accurately identify of the Saccharomyces species most commonly involved in fermentation processes using a PCR-based assay.

SIGNIFICANCE AND IMPACT OF THE STUDY

The method may be used for routine identification of the most common Saccharomyces sensu stricto yeasts involved in industrial fermentation processes in less than 3 h.

Direct demonstration of P-selectin- and VCAM-1-dependent mononuclear cell rolling in early atherosclerotic lesions of apolipoprotein E-deficient mice

Apolipoprotein E-deficient (ApoE-/-) mice develop atherosclerotic lesions throughout the arterial tree, including the carotid bifurcation. Although the expression of adhesion molecules such as ICAM-1, vascular cell adhesion molecule-1 (VCAM-1), and P-selectin on endothelium that overlie atherosclerotic plaques has been implicated in monocyte recruitment to developing lesions, monocyte adhesion in atherosclerotic vessels has not been observed directly. To investigate which adhesion molecules may be important in monocyte adhesion to atherosclerotic lesions, an isolated mouse carotid artery preparation was developed and perfused with mononuclear cells. We show rolling and attachment of the human monocytic cell line U937 and the mouse monocyte-macrophage cell line P388D1 in carotid arteries from 10- to 12-week-old ApoE-/- and C57BL/6 wild-type mice fed a Western-type diet (21% fat wt/wt) for 4 to 5 weeks. No rolling was observed in carotid arteries from C57BL/6 or BALB/c wild-type mice fed a chow diet and little was observed in BALB/c mice fed a Western-type diet. This model represents early lesion development as shown by minimal macrophage infiltration in the intima of carotid arteries from ApoE-/- mice fed a Western-type diet. Rolling was observed at shear stresses that were characteristic of the low-shear recirculation zone near the carotid bifurcation. Mononuclear cell attachment and rolling were significantly inhibited by monoclonal antibody blockade of P-selectin or its leukocyte ligand P-selectin glycoprotein ligand-1. Rolling velocities increased after monoclonal antibody blockade of mononuclear cell alpha4-integrin or VCAM-1, which indicates that alpha4-integrin interacting with VCAM-1 stabilizes rolling interactions and prolongs monocyte transit times.

The roles of L-selectin, beta 7 integrins, and P-selectin in leukocyte rolling and adhesion in high endothelial venules of Peyer's patches

Lymphocyte trafficking into Peyer's patches requires beta 7 integrins and L-selectin. Here, we use intravital microscopy to examine leukocyte rolling and adhesion in Peyer's patch high endothelial venules (HEV) of wild-type, L-selectin-deficient (L-/-), beta 7 integrin-deficient (beta 7-/-), and beta 7/L(-/-) mice. Although the leukocyte rolling flux fraction was reduced by 70%, Peyer's patches in L-/- mice were of normal size and cellularity. In beta 7-/- mice, the rolling flux fraction was normal, but the number of adherent leukocytes in HEV was greatly reduced. The median leukocyte rolling velocity was reduced in L-/- mice and increased in beta 7-/- mice, suggesting that beta 7 integrins and L-selectin mediate rolling in Peyer's patch HEV at different velocities. beta 7/L(-/-) exhibited both a low rolling flux fraction and low adhesion and had severely reduced Peyer's patch size and cellularity. The residual rolling in these mice was completely blocked by a P-selectin mAb. A significant P-selectin component was also detected in the other genotypes. Twenty-six percent of B and T lymphocytes isolated from Peyer's patches of wild-type mice expressed functional ligands for P-selectin, and this fraction was increased to 57% in beta 7/L(-/-) mice. Peyer's patch HEV were found to express P-selectin under the conditions of intravital microscopy, but not in situ. Our data suggest a novel P-selectin dependent mechanism of lymphocyte homing to Peyer's patches. In situ, beta 7 integrins and L-selectin account for all lymphocyte homing to Peyer's patches, but P-selectin-dependent rolling, as induced by minimal trauma, may support trafficking of effector T lymphocytes to Peyer's patches.

CD24 mediates rolling of breast carcinoma cells on P-selectin

P-selectin mediates rolling of neutrophils and other leukocytes on activated endothelial cells and platelets through binding to P-selectin glycoprotein ligand-1 (PSGL-1). Certain PSGL-1 negative tumor cell lines can bind P-selectin under static conditions through the GPI-linked surface mucin, CD24, but the physiological significance of this interaction and whether it can occur under flow conditions is not known. Here, we show that CD24+ PSGL-1- KS breast carcinoma cells attach to and roll on recombinant P-selectin under a continuous wall shear stress, although at a lower density and higher velocity than CD24+ PSGL-1+ cells, such as HL-60. Adding excess soluble CD24 or removing CD24 from the cell surface with phosphatidylinositol-phospholipase C (PI-PLC) significantly reduced KS cell rolling on P-selectin. The ability of KS cells to roll on P-selectin was positively correlated with the CD24 expression level. Comparison with three other CD24+ cell lines established that expression of sialyl-Lewis(x) antigen was also necessary for CD24-mediated rolling on P-selectin. CD24 purified from KS cells supported rolling of P-selectin transfectants, but not L-selectin transfectants. Finally, KS cells rolled on vascular endothelium in vivo in a P-selectin-dependent manner. Together our data show that CD24 serves as a ligand for P-selectin under physiological flow conditions. Interaction of tumor cells with P-selectin via CD24 may be an important adhesion pathway in cancer metastasis.

Gene-targeted mice reveal importance of L-selectin-dependent rolling for neutrophil adhesion

It has not been determined whether L-selectin-mediated rolling can promote leukocyte adhesion in vivo independent of P- and E-selectin. We used intravital microscopy of E- and P-selectin double-mutant mice (E-/P-) stimulated with tumor necrosis factor-alpha for 6-8 h to investigate the importance of L-selectin-dependent rolling in cremaster muscle venules. Rolling leukocyte flux in E-/P- mice was 9 +/- 2 cells/min compared with 77 +/- 17 cells/min in wild-type (WT) mice. Pretreatment with the L-selectin monoclonal antibody MEL-14 significantly reduced rolling in both E-/P- (by 89%) and WT mice (by 79%). L-selectin-dependent rolling in E-/P- mice resulted in leukocyte adhesion comparable to that seen in WT mice. MEL-14 pretreatment of E-/P- mice reduced leukocyte adhesion by 50%. The majority (approximately 80%) of intravascular leukocytes in both WT and E-/P- mice were neutrophils. We conclude that L-selectin can mediate rolling that results in sufficient leukocyte recruitment to account for the robust inflammatory response seen in E-/P- mice at later times.

Functional characterization of L-selectin ligands on human neutrophils and leukemia cell lines: evidence for mucinlike ligand activity distinct from P-selectin glycoprotein ligand-1

Recent reports have shown that leukocyte-leukocyte adhesion is dependent on L-selectin and that leukocyte recognition of L-selectin may be mediated by P-selectin glycoprotein ligand-1 (PSGL-1). We show that the specific attachment and rolling of human neutrophils and the leukemia cell lines HL-60 and U937 on immobilized, purified L-selectin under continuous shear stress is only partially inhibited by treatment with the PSGL-1 monoclonal antibody (MoAb), KPL1 (41% to 53% inhibition), suggesting that L-selectin ligand activity in addition to PSGL-1 may mediate myeloid cell rolling on L-selectin. K562 cells cotransfected with cDNAs encoding alpha (1,3)fucosyltransferase-VII (FucT-VII) and PSGL-1 rolled on L-selectin. Adhesion of FucT-VII-PSGL-1 transfectants to L-selectin was completely blocked by MoAb KPL1, indicating that both L-selectin and P-selectin bind similar sites on PSGL-1. In support of existence of a non-PSGL-1 L-selectin ligand activity on leukocytes, an HL-60 membrane preparation immunodepleted of PSGL-1 supported rolling of L-selectin, but not P-selectin transfectants. Treatment of HL-60 cells with O-sialoglycoprotein endopeptidase inhibited attachment and rolling on L-selectin and P-selectin. However, neuraminidase treatment completely blocked HL-60 rolling on L-selectin, but not P-selectin, suggesting L-selectin and P-selectin ligand activities have different contributions of sialic acid. These findings indicate that myeloid cells express sialylated, O-linked glycoprotein ligand activity independent of PSGL-1 that supports L-selectin-mediated rolling.

Differential effect of E-selectin antibodies on neutrophil rolling and recruitment to inflammatory sites

The selectins are inducible adhesion molecules critically important for the inflammatory response. We investigate here the functional effects of three monoclonal antibodies (MoAbs) raised against murine E-selectin (9A9, 10E6, and 10E9.6) on neutrophil recruitment in vivo, leukocyte rolling and circulating leukocyte concentrations in vivo, and adhesion of myeloid cells to E-selectin transfectants and recombinant E-selectin-IgG fusion protein in vitro. MoAbs 9A9 and 10E6 map to the lectin and epidermal growth factor (EGF)-like domains of murine E-selectin, whereas 10E9.6 binds to the consensus repeat region. 10E9.6 blocked neutrophil recruitment in a model of thioglycollate-induced peritonitis in Balb/c mice by more than 90% but had no effect in C57BL/6 mice. 9A9 and 10E6 blocked neutrophil recruitment in this assay only when combined with a P-selectin antibody, 5H1. Neither 9A9 nor 10E9.6 alone blocked leukocyte rolling in tumor necrosis factor-alpha-treated venules of Balb/c mice, but 9A9 almost completely inhibited leukocyte rolling when combined with the function-blocking murine P-selectin MoAb, RB40.34. In contrast, 10E9.6 had no effect on leukocyte rolling in RB40.34-treated Balb/c or C57BL/6 mice. 10E9.6 did not affect adhesion of myeloid cells to E-selectin transfectants or attachment, rolling, and detachment of myeloid cells to murine E-selectin-IgG fusion protein. However, adhesion was completely blocked in the same assays by 9A9. Taken together, these results indicate that E-selectin serves a function, other than rolling, that appears to be critically important for neutrophil recruitment to inflammatory sites in Balb/c mice.

Effect of anti-inflammatory drugs on myeloperoxidase-dependent hydroxyl radical generation by human neutrophils

Neutrophils comprise a group of leukocytes that play a pivotal role in inflammation and vascular diseases like ischemia/reperfusion. These activated phagocytic cells are drawn to the site of injury, secreting superoxide and other oxidants derived from the formation of this free radical. This series of events frequently results in localized tissue damage. Surprisingly, free radical scavengers frequently offer only minimal relief. Why this is so may be due, in part, to our limited understanding of mechanisms that govern generation of free radicals in these settings. Although the metal ion-catalyzed Haber-Weiss reaction is considered the classical pathway for neutrophil-derived hydroxyl radical, an alternative mechanism, such as the myeloperoxidase-dependent pathway, may undoubtedly contribute to the formation of this free radical by stimulated neutrophils. In this study, we explored this possibility by investigating the role of different classes of anti-inflammatory drugs to ameliorate hydroxyl radical generation via the myeloperoxidase-dependent pathway. In this paper, we report that meclofenamic acid inhibited myeloperoxidase-dependent hydroxyl radical generation through scavenging of hypochlorous acid and not by direct inhibition of myeloperoxidase. The importance of these results with regard to the clinical efficacy of this anti-inflammatory compound remains to be determined as studies into the significance of myeloperoxidase-dependent hydroxyl radical formation in inflammatory tissue injury continue.

Free radicals and phagocytic cells

Phagocytes mediate their innate immunological response by releasing products that damage invading microorganisms. These products include proteins such as lysozyme, peroxidases, and elastase as well as reactive oxygen species such as superoxide, hydrogen peroxide, hypohalous acid, and hydroxyl radical. Although it is clear that many phagocytic secretory products have direct cytotoxic potential, understanding is limited of how multiple products interact to generate and modulate the cytotoxic response. This review focuses on recent findings that elucidate the biochemical nature of secretory product interaction in the formation of free radicals, particularly the highly reactive hydroxyl radical. The possible role of these reactions in phagocyte microbicidal activity and inflammatory tissue injury is discussed.

A kinetic approach to the selection of a sensitive spin trapping system for the detection of hydroxyl radical

The spin trap 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) alone, as well as DMPO or N-tert-butyl-alpha-phenylnitrone (PBN) in the presence of excess dimethyl sulfoxide (Me2SO), have been used as spin trapping systems for the detection of hydroxyl radical. However, the instability of DMPO and many of its corresponding spin-trapped adducts has limited the usefulness of this spin trap, particularly in biological systems. Spin trapping of multiple free radicals by the PBN/Me2SO system may undermine the sensitivity of this method to detect small, yet biologically significant amounts of hydroxyl radical. The present study was undertaken to select a spin trapping system with greater sensitivity and selectivity toward.OH than DMPO, DMPO/Me2SO, or PBN/Me2SO. We report that alpha-hydroxyethyl radical, resulting from the reaction of photolytically generated.OH with excess ethanol is spin trapped by 4-pyridyl-1-oxide-N-tert-butylnitrone (4-POBN) with a second-order rate constant nearly 10-fold greater than that for DMPO or PBN. In contrast to DMPO spin-trapped adducts, the alpha-hydroxyethyl radical adduct of 4-POBN, 4-POBN-CH(CH3)OH, is resistant to reduction by superoxide, even in the presence of cysteine. The efficiency of spin trapping and the marked stability of the resulting spin-trapped adduct confer a high degree of sensitivity and demonstrate the potential application of 4-POBN/ETOH toward the detection of hydroxyl radical in biological systems.

Spin trapping evidence for myeloperoxidase-dependent hydroxyl radical formation by human neutrophils and monocytes

Using the electron spin resonance/spin trapping system, 4-pyridyl 1-oxide N-tert-butylnitrone (4-POBN)/ethanol, hydroxyl radical was detected as the alpha-hydroxyethyl spin trapped adduct of 4-POBN, 4-POBN-CH(CH3)OH, from phorbol 12-myristate 13-acetate-stimulated human neutrophils and monocytes without the addition of supplemental iron. 4-POBN-CH(CH3)OH was stable in the presence of a neutrophil-derived superoxide flux. Hydroxyl radical formation was inhibited by treatment with superoxide dismutase, catalase, and azide. Treatment with a series of transition metal chelators did not appreciably alter 4-POBN-CH(CH3)OH, which suggested that hydroxyl radical generation was mediated by a mechanism independent of the transition metal-catalyzed Haber-Weiss reaction. Kinetic differences between transition metal-dependent and -independent mechanisms of hydroxyl radical generation by stimulated neutrophils were demonstrated by a greater rate of 4-POBN-CH(CH3)-OH accumulation in the presence of supplemental iron. Detection of hydroxyl radical from stimulated monocyte-derived macrophages, which lack myeloperoxidase, required the addition of supplemental iron. The addition of purified myeloperoxidase to an enzymatic superoxide generating system resulted in the detection of hydroxyl radical that was dependent upon the presence of chloride and was inhibited by superoxide dismutase, catalase, and azide. These findings implicated the reaction of hypochlorous acid and superoxide to produce hydroxyl radical. 4-POBN-CH(CH3)OH was not observed upon stimulation of myeloperoxidase-deficient neutrophils, whereas addition of myeloperoxidase to the reaction mixture resulted in the detection of hydroxyl radical. These results support the ability of human neutrophils and monocytes to generate hydroxyl radical through a myeloperoxidase-dependent mechanism.

Sexual behavior triggers the appearance of non-neuronal cells containing gonadotropin-releasing hormone-like immunoreactivity

Gonadotropin-releasing hormone (GnRH) regulates the secretion of pituitary gonadotropins and facilitates the display of sexual behavior. We report that in doves, following a brief period of courtship, non-neuronal cells containing GnRH-like immunoreactivity (ir) are seen in the habenula of both male and female doves. These cells appear to be translocated from either the cerebrospinal fluid or from capillaries in the pia or choroid plexus into the parenchyma of the brain. Immunoreactive cells are virtually absent in the habenula in control animals housed alone. The identity of the ir cells that enter the habenula is unknown but they would appear to be of either the macrophage or the mast cell lineage. Both of these blood-derived cells have heterochromatic nuclei and irregular cell surfaces with many filamentous processes, as do the GnRH-ir cells. The vacuolated granules of the ir cells could be indicative of mast cell degranulation or of endocytic vesicles of a phagocytosing cell. These data suggest that there is a population of cells within the habenula that are of similar size and morphology to the GnRH-ir ceils and are metachromatic when stained with toluidine blue. The latter is a property of heparin-containing mast cells. Lineage specific markers that permit a double-label study will be required to determine the exact nature of the GnRH-ir cells. Whatever their lineage, the translocation of non-neuronal cells into the undamaged adult central nervous system has not been described previously, and may provide a means of delivering biologically active substances into specific brain regions.

[Use of contraceptives by a Brazilian population]

Um grupo de 245 mulheres moradoras em Mogi das Cruzes (Estado de S. Paulo, Brasil) foi questionado com relação ao uso de anticoncepcionais, história obstétrica, mortalidade infantil e atitudes correlacionadas com a limitação da natalidade. As respostas foram classificadas segundo idade e nível de renda da informante. Apenas 49% das mulheres empregavam medidas anticoncepcionais, das quais 42% recorriam aos anovulatórios. Esta prática era mais freqüente entre as mulheres jovens, e aquelas pertencentes às famílias melhores situadas economicamente. Não só era mais baixa a natalidade nas mulheres que se valiam de anticoncepcionais, mas esta prática acompanhava-se de sensível redução no número de abortos e da mortalidade infantil. O efeito foi mais pronunciado entre aquelas que empregavam os anovulatórios.