Nitric oxide specifically inhibits integrin-mediated platelet adhesion and spreading on collagen.

BACKGROUND: Nitric oxide (NO) inhibits platelet adhesion to collagen, although the precise molecular mechanisms underlying this process are unclear. OBJECTIVES: Collagen-mediated adhesion is a multifaceted event requiring multiple receptors and platelet-derived soluble agonists. We investigated the influence of NO on these processes. RESULTS: S-nitrosoglutathione (GSNO) induced a concentration-dependent inhibition of platelet adhesion to immobilized collagen. Maximal adhesion to collagen required platelet-derived ADP and TxA(2). GSNO-mediated inhibition was lost in the presence of apyrase and indomethacin, suggesting that NO reduced the availability of, or signaling by, ADP and TxA(2). Exogenous ADP, but not the TxA(2) analogue U46619, reversed the inhibitory actions of GSNO on adhesion. Under adhesive conditions NO inhibited dense granule secretion but did not influence TxA(2) generation. These data indicated that NO may block signaling by TxA(2) required for dense granule secretion, thereby reducing the availability of ADP. Indeed, we found TxA(2)-mediated activation of PKC was required to drive dense granule secretion, a pathway that was inhibited by NO. Because our data demonstrated that NO only inhibited the activation-dependent component of adhesion, we investigated the effects of NO on individual collagen receptors. GSNO inhibited platelet adhesion and spreading on alpha(2)beta(1) specific peptide ligand GFOGER. In contrast, GSNO did not inhibit GPVI-mediated adhesion to collagen, or adhesion to the GPVI specific ligand, collagen related peptide (CRP). CONCLUSIONS: NO targets activation-dependent adhesion mediated by alpha(2)beta(1), possibly by reducing bioavailability of platelet-derived ADP, but has no effect on activation-independent adhesion mediated by GPVI. Thus, NO regulates platelet spreading and stable adhesion to collagen.

Globular adiponectin increases cGMP formation in blood platelets independently of nitric oxide.

BACKGROUND: Platelet-derived nitric oxide (NO) has been shown to play conflicting roles in platelet function, although it is accepted that NO mediates its actions through soluble guanylyl cyclase (sGC). This confusion concerning the roles of platelet NO may have arisen because of an uncharacterized mechanism for activation of sGC. OBJECTIVES: To examine the ability of the novel platelet agonist globular adiponectin (gAd) to stimulate the NO-independent cGMP-protein kinase G (PKG) signaling cascade. METHODS: We used three independent markers of NO signaling, [(3)H]l-citrulline production, cGMP accrual, and immunoblotting of vasodilator-stimulated phosphoprotein (VASP), to examine the NO signaling cascade in response to gAd. RESULTS: gAd increased platelet cGMP formation, resulting in a dose- and time-dependent increase in phospho-VASP(157/239). Phosphorylation of VASP in response to gAd was mediated by both protein kinase A and PKG. Importantly, cGMP formation occurred in the absence of NO synthase (NOS) activation and in the presence of NOS inhibitors. Indeed, inhibition of the NOS signaling cascade had no influence on gAd-mediated platelet aggregation. Exploration of the mechanism demonstrated that NO-independent cGMP formation, phosphorylation of VASP and association of sGCalpha(1) with heat shock protein-90 induced by gAd were blocked under conditions that inhibited Src kinases, implying a tyrosine kinase-dependent mechanism. Indeed, sGCalpha1 was reversibly tyrosine phosphorylated in response to gAd, collagen, and collagen-related peptide, an effect that required Src kinases and downstream Ca(2+) mobilization. CONCLUSIONS: These data demonstrate activation of the platelet cGMP signaling cascade by a novel tyrosine kinase-dependent mechanism in the absence of NO.

Globular adiponectin induces platelet activation through the collagen receptor GPVI-Fc receptor gamma chain complex.

BACKGROUND: The adipocyte-derived cytokine, adiponectin (Ad), exerts potent vascular effects, although the direct effects of Ad on blood platelets are unclear. OBJECTIVE: The influence of globular Ad (gAd) on blood platelet function was investigated. RESEARCH DESIGN AND METHODS: We measured platelet aggregation and tyrosine phosphorylation signaling events in human and mouse platelets. The ability of gAd to activate Glycoprotein VI (GPVI) activity was determined with a NFAT luciferase reporter assay. RESULTS: gAd, but not full length Ad, induced rapid aggregation and granule secretion of human and mouse platelets through a pathway that is ablated under conditions of Src kinase inhibition, indicating a tyrosine kinase-dependent mechanism. Consistent with this, gAd stimulates rapid tyrosine phosphorylation of several proteins in human and mouse platelets. The pattern of increase in tyrosine phosphorylation was similar to that induced by collagen, with the tyrosine kinase Syk and PLCgamma2 being identified among the list of tyrosine phosphorylated proteins. As collagen activates platelet through the GPVI-Fc receptor gamma-chain (FcRgamma) complex, we used FcRgamma null platelets (which also lack GPVI) to explore the mechanism by which gAd stimulates platelets. Stimulation of tyrosine phosphorylation and platelet aggregation by gAd was abolished in FcRgamma null platelets and markedly reduced in the absence of PLCgamma2. Further, GPVI was confirmed as a collagen receptor for gAd by increased luciferase activity in Jurkat T-cells transfected with GPVI. CONCLUSIONS: We identify gAd as a novel ligand for GPVI that stimulates tyrosine kinase-dependent platelet aggregation. Our data raise the possibility that gAd may promote unwanted platelet activation at sites of vascular injury.

Unresolved roles of platelet nitric oxide synthase.

Endothelial-derived nitric oxide (NO) is a key regulator of platelet function, inhibiting both adhesion to the extracellular matrix and aggregation at sites of vascular injury. Platelets also have the capacity to synthesize and release bioactive NO, which is thought to make a significant contribution to the vascular pool of NO. The regulation of platelet NO production is poorly understood and studies examining the physiological role of platelet-derived NO have produced contradictory and controversial findings. In the present article, we discuss the current understanding of the biochemical and molecular regulation of platelet NO synthesis and outline the potential physiological and clinical significance of this molecule.

Von Willebrand factor activates endothelial nitric oxide synthase in blood platelets by a glycoprotein Ib-dependent mechanism.

BACKGROUND: The molecular regulation of endothelial nitric oxide synthase (eNOS) in blood platelets and the signalling events induced by platelet-derived NO are poorly defined. In particular, the ability of von Willebrand factor (VWF) to stimulate cyclic guanosine monophosphate (cGMP) formation in platelets has produced conflicting data. OBJECTIVES: To determine the mechanisms leading to eNOS activation and clarify the downstream signaling pathways activated by platelet-derived NO in response to VWF. METHODS: We used three independent markers of NO signaling, [3H] l-citrulline production, cGMP accrual and immunoblotting of vasodilator-stimulated phosphoprotein (VASP) to examine the NO signaling cascade in response to VWF. RESULTS: VWF increased NO synthesis and bioavailability, as evidenced by increased [3H] l-citrulline production and cGMP accrual, respectively. VWF-induced eNOS activation was GPIb-IX-dependent and independent of integrin alpha(IIb)beta3. cGMP formation in response to VWF required Ca2+ mobilization, Src family kinases, phosphatidylinositol 3-kinase and phospholipase C, but not protein kinase C. This suggests that a cross-talk between the signaling mechanisms regulates platelet activation and NO synthesis. VWF-induced cGMP accrual was completely blocked by apyrase and indomethacin, demonstrating an essential role for platelet-derived ADP and thromboxane A2 (TxA2). Elevated cGMP levels led to increased VASP phosphorylation at serine239 that was both protein kinase G (PKG)- and protein kinase A (PKA)-dependent. CONCLUSIONS: We demonstrate that VWF activates eNOS through a specific Ca2+-dependent GPIb receptor-signaling cascade that relies on the generation of platelet-derived ADP and TxA2. Furthermore, we provide the first evidence to suggest that platelet derived-NO/cGMP activates PKA in addition to PKG.

Miocardiopatía alcohólica / Alcoholic cardiomyopathy

No disponible

[Morphogenesis of the sexual phase of six Mexican species of the Dryopteris (Dryopteridaceae), Part II]. / Morfogénesis de la fase sexual de seis especies mexicanas del género Dryopteris (Dryopteridaceae), Parte II.

The development of the sexual phase of six Mexican species of Dryopteris is described and compared. Spores of all studied species are monolete, ellipsoid and have a rugose surface; the perine is folded, brown to dark brown, with a tubercled outline. Germination pattern is of the Vittaria-type and the development pattern of the prothallia is of the Aspidium-type. Gametangia are of the common type for the leptosporangiate advanced ferns. First leaves of the sporophytes appear 258-265 after sowing and apparently in Dryopteris pseudo-filix-mas the sporophyte have an apogamic origin (80 days). To make a comparative analysis of gametophytic characteristics in the twelve Mexican species and conclude of germination is of the Vittaria-type and development pattern prothallial is of the Aspidium-type, and unicelular trichomes on margin and superficial gametophytic to yield irregular aspect are characteristics to yield unit and characteristic to genera to conform Dryopteridaceae family (sensu Moran 1995) with the exception of Didymochlaena genus.

Intervenciones farmacéuticas (parte ii): validación de la metodología utilizada para medir el impacto / Pharmaceutical interventions (part II): validation of the methodology used to measure impact

El objetivo del presente estudio es validar la metodología de evaluación y documentación de las intervenciones realizadas por el farmacéutico para definir un instrumento estandarizado y homogéneo aplicable en la práctica clínica diaria. Para llevar a cabo esta validación se seleccionaron aleatoriamente 15 intervenciones de las realizadas y codificadas previamente para su posterior recodificación por farmacéuticos adjuntos del propio hospital y de diferentes hospitales externos. La concordancia en la clasificación de las intervenciones se evaluó mediante la prueba kappa o mediante la prueba rho de Spearman. Los valores de kappa para el código de tipo de intervención y de impacto fueron 0,790 y 0,826 entre los farmacéuticos del servicio y 0,699 y 0,691 entre los externos, respectivamente. El valor del coeficiente de Spearman para el código de significación fue 0,480 (p < 0,01) entre los farmacéuticos del servicio y 0,390 (p < 0,01) entre los externos. La metodología validada presentada en este trabajo sirve de base para evaluar el impacto de las intervenciones del farmacéutico de forma continuada (AU)

Intervenciones farmacéuticas (parte i): metodología y evaluación / Pharmaceutical interventions (part I): methodology and assessment

El principal objetivo de la atención farmacéutica es mejorar la calidad de la atención al paciente, garantizando la terapéutica más idónea. Con el fin de demostrar el impacto en la atención al paciente individualizado es necesario que los farmacéuticos registren las actividades clínicas y evalúen sus resultados. En el presente estudio se describen las intervenciones realizadas por el farmacéutico a través de la monitorización terapéutica ligada al sistema de distribución de medicamentos en dosis unitarias, así como la metodología y resultados de la evaluación del impacto de las intervenciones en la atención al paciente. En un período de cuatro años se registraron 22.786 intervenciones (21 intervenciones/día). En la evaluación de las intervenciones (n = 1.302) se obtuvo que el 88,5 por ciento eran muy significativas o significativas. Los resultados muestran que el farmacéutico tiene un papel importante en la atención al paciente y que el valor añadido que se aporta al proceso de utilización de medicamentos conduce a una mejora de la atención al paciente (AU)

[Pharmacokinetics of vancomycin in neonates of postconceptional age less than or equal to 32 weeks]. / Comportamiento farmacocinético de la vancomicina en neonatos de edad postconcepcional < or = 32 semanas. Propuesta de una pauta de dosificación.

The objective of the present study was to analyze the pharmacokinetic behavior of vancomycin in neonates of postconceptional age < or = 32 weeks (n = 44). The elimination of the antibiotic was influenced by the concomitant treatment with indomethacin and mechanical ventilation. Close monitoring of renal function of the neonate and vancomycin dosage individualization are mandatory when the above factors are present. Vancomycin dosage guidelines have been determined according to serum creatinine of these premature patients.

Laboratory of Caribbean Brain Research Organization in the decade of the brain midpoint. Results in reaching behavior--interferences of subcortical motor centers, neurotransmitter blocking and brain function modeling.

CARIBRO was founded in response to the United Nations declaration that the 1990s be designated the Decade of the Brain. The Program of Action is: 1. Annual meetings; 2. Training courses of the Caribbean School of Neurosciences; 3. Network scientific programs; 4. Fellowship programs; and 5. Dissemination of information on neuroscience. In the same program, a CARIBRO Laboratory was created in one of the Medical Faculties of Havana with the aim to teach students from the Caribbean in neuroscience research. As part of this program, we have been working in lateralized motor functions. Preliminary results in rats show that reaching acquisition allows classification of the animals as right-handed (40%), left-handed (40%), and ambidextrous (20%). Electrolytic lesion of caudate nucleus or amygdala impairs lateralized response. Contralateral lesions increase reaching attempts. Ipsilateral lesions to the preferred forepaw do not affect the reaction. The results remain the same 10, 20, and 90 d after the interference. Pharmacological experiments showed that trihexiphenidil (0.1 mg/kg i.p.) induced handedness reversion in 50% if the animals, whereas haloperidol (1 mg/kg i.p.) produced immobility, tremor, and autonomic symptoms. This effect remained the same in young as well as in old animals. We are also working on mathematical modelation. In this sense, preliminary reports about a model for synaptic modification in the framework of the Fukushima hypothesis is discussed.

[Sepsis caused by coagulase-negative Staphylococcus in the newborn infant. Clinical and therapeutic aspects]. / Sepsis por estafilococo coagulasa negativo en el recién nacido. Aspectos clínicos y terapéuticos.

This study deals with sepsis caused by coagulase-negative stapylococci in a neonatal intensive care unit over a period of four years and eleven months. The global incidence was 20.7/1000 (50 cases out of a total of 2,416 admissions) and was higher in newborns with lower weight and with a shorter gestational age. The most significant clinical manifestations were fever, paleness, and apnea/bradycardia. In all cases the germ was sensitive to vancomycin. Evolution was favourable in all patients, in spite of the initial gravity of some cases. Sepsis due to coagulase-negative staphylococci is the most frequent cause of nosocomial infection in our environment.

[Subcutaneous adrenaline versus inhaled salbutamol in the treatment of childhood asthmatic crisis]. / Adrenalina subcutánea versus salbutamol inhalado en el tratamiento de la crisis asmática infantil.

As a bronchodilator, inhaled salbutamol has been shown to be as pharmacologically effective as epinephrine. However the use of the pressurised aerosol is difficult for pediatric patients (mainly under the age of six). The use of spacers (inhalation chambers) could solve this problem. This study was undertaken to compare the clinical effectiveness and toxicity of these two drugs and to try to establish dosage schedules of inhaled salbutamol with spacer in the treatment of acute asthma. The study population consisted of 100 children who were admitted to the emergency room at our hospital with acute asthma. One group receives 0.01 mg/kg of epinephrine (A) (maximum 0.3 mg), the other two groups received inhaled salbutamol (S-1 = 4 puffs and S-2 = 7 puffs) in a period of 20 minutes. Clinical effectiveness was measured by the score of Wood-Downes at 0, 30 and 60 minutes; and no statistical differences were observed between the three groups. The clinical effectiveness was similar in the three groups and the side effects (especially the increase of heart rate) was higher in epinephrine group. Inhaled salbutamol is as effective as subcutaneous epinephrine in management of children in acute bronchoconstricting episodes with less side effects.

Effects of hypothalamic and amygdaloid stimulation on reaching behaviour in the rat.

Thirty adult rats were trained in a reaching behaviour schedule, after which bipolar steel electrodes were bilaterally implanted into the ventromedial hypothalamus (VMH), lateral hypothalamic area (LHA) or basolateral amygdala (BLA). On subsequent training sessions, these structures were electrically stimulated employing a movement-synchronized stimulation design. The results show that VMH stimulation produces aversive effects: the animals go away from the feeder after the first stimulus. Reaching impairment resulting from LHA or BLA stimulation mainly affected the grasping phase; additionally, repetition of movement sequence was observed. The results are discussed in the framework of Kornhuber's concept of preprogrammed ballistic movements.

Modificaciones de los componentes de proyecciones transcallosos hipersincrónicos durante la depresión cortical propagada por la picrotoxina / Changes in the components of hypersynchronic transcallous projections during crtical depression induced by picrotoxin

En el presente trabajo se analiza el efecto de la aplicación de picrotoxina en el área cortical de proyección de focos penicilínicos corticales o de respuestas transcallosas evocadas por estimulaciones eléctricas (PFP y RET respectivamente); antes, durante y después de ondas de depresión cortical propagada (DCP). Los resultados muestran que la picrotoxina provoca aumento en la amplitud de las RET y PFP, sobre todo a punto de partida del componente negativo de estas respuestas; durante las ondas de DCP, se observó depresión inicial de las respuestas evocadas, seguido de variaciones del componente negativo y positivo. Se discuten los resultados sobre la base de la acción de la picrotoxina en las sinapsis inhibitorias corticales