Pilar Martínez

Differential structural and functional changes in penile and coronary arteries from obese Zucker rats.

Erectile dysfunction frequently coexists with coronary artery disease and has been proposed as a potential marker for silent coronary artery disease in type 2 diabetes. In the present study, we comparatively assessed the structural and functional changes of both penile arteries (PAs) and coronary arteries (CAs) from a prediabetic animal model. PAs and CAs from 17- to 18-wk-old obese Zucker rats (OZRs) and from their control counterparts [lean Zucker rats (LZRs)] were mounted in microvascular myographs to evaluate vascular function, and stained arteries were subjected to morphometric analysis. Endothelial nitric oxide (NO) synthase (eNOS) protein expression was also assessed. The internal diameter was reduced and the wall-to-lumen ratio was increased in PAs from OZRs, but structure was preserved in CAs. ACh-elicited relaxations were severely impaired in PAs but not in CAs from OZRs, although eNOS expression was unaltered. Contractions to norepinephrine and 5-HT were significantly enhanced in both PAs and CAs, respectively, from OZRs. Blockade of NOS abolished endothelium-dependent relaxations in PAs and CAs and potentiated norepinephrine and 5-HT contractions in arteries from LZRs but not from OZRs. The vasodilator response to the phosphodiesterase 5 inhibitor sildenafil was reduced in both PAs and CAs from OZRs. Pretreatment with SOD reduced the enhanced vasoconstriction in both PAs and CAs from OZRs but did not restore ACh-induced relaxations in PAs. In conclusion, the present results demonstrate vascular inward remodeling in PAs and a differential impairment of endothelial relaxant responses in PAs and CAs from insulin-resistant OZRs. Enhanced superoxide production and reduced basal NO activity seem to underlie the augmented vasoconstriction in both PAs and CAs. The severity of the structural and functional abnormalities in PAs might anticipate the vascular dysfunction of the more preserved coronary vascular bed.

Insulin resistance in penile arteries from a rat model of metabolic syndrome

BACKGROUND AND PURPOSE Metabolic and cardiovascular abnormalities accompanying metabolic syndrome, such as obesity, insulin resistance and hypertension, are all associated with endothelial dysfunction and are independent risk factors for erectile dysfunction. The purpose of the present study was to investigate the vascular effects of insulin in penile arteries and whether these effects are impaired in a rat model of insulin resistance and metabolic syndrome.

Altered arachidonic acid metabolism via COX‐1 and COX‐2 contributes to the endothelial dysfunction of penile arteries from obese Zucker rats

Background and purpose:  The aim of the current study was to investigate the role of arachidonic acid (AA) metabolism via cyclooxygenase (COX) in the endothelial dysfunction of penile arteries from pre‐diabetic, obese Zucker rats (OZR).

Upregulation of SK3 and IK1 Channels Contributes to the Enhanced Endothelial Calcium Signaling and the Preserved Coronary Relaxation in Obese Zucker Rats

Background and Aims Endothelial small- and intermediate-conductance KCa channels, SK3 and IK1, are key mediators in the endothelium-derived hyperpolarization and relaxation of vascular smooth muscle and also in the modulation of endothelial Ca2+ signaling and nitric oxide (NO) release. Obesity is associated with endothelial dysfunction and impaired relaxation, although how obesity influences endothelial SK3/IK1 function is unclear. Therefore we assessed whether the role of these channels in the coronary circulation is altered in obese animals. Methods and Results In coronary arteries mounted in microvascular myographs, selective blockade of SK3/IK1 channels unmasked an increased contribution of these channels to the ACh- and to the exogenous NO- induced relaxations in arteries of Obese Zucker Rats (OZR) compared to Lean Zucker Rats (LZR). Relaxant responses induced by the SK3/IK1 channel activator NS309 were enhanced in OZR and NO- endothelium-dependent in LZR, whereas an additional endothelium-independent relaxant component was found in OZR. Fura2-AM fluorescence revealed a larger ACh-induced intracellular Ca2+ mobilization in the endothelium of coronary arteries from OZR, which was inhibited by blockade of SK3/IK1 channels in both LZR and OZR. Western blot analysis showed an increased expression of SK3/IK1 channels in coronary arteries of OZR and immunohistochemistry suggested that it takes place predominantly in the endothelial layer. Conclusions Obesity may induce activation of adaptive vascular mechanisms to preserve the dilator function in coronary arteries. Increased function and expression of SK3/IK1 channels by influencing endothelial Ca2+ dynamics might contribute to the unaltered endothelium-dependent coronary relaxation in the early stages of obesity.

Hydrogen Sulfide Plays a Key Role in the Inhibitory Neurotransmission to the Pig Intravesical Ureter

According to previous observations nitric oxide (NO), as well as an unknown nature mediator are involved in the inhibitory neurotransmission to the intravesical ureter. This study investigates the hydrogen sulfide (H2S) role in the neurogenic relaxation of the pig intravesical ureter. We have performed western blot and immunohistochemistry to study the expression of the H2S synthesis enzymes cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS), measurement of enzymatic production of H2S and myographic studies for isometric force recording. Immunohistochemical assays showed a high CSE expression in the intravesical ureter muscular layer, as well as a strong CSE-immunoreactivity within nerve fibres distributed along smooth muscle bundles. CBS expression, however, was not consistently observed. On ureteral strips precontracted with thromboxane A2 analogue U46619, electrical field stimulation (EFS) and the H2S donor P-(4-methoxyphenyl)-P-4-morpholinylphosphinodithioic acid (GYY4137) evoked frequency- and concentration-dependent relaxations. CSE inhibition with DL-propargylglycine (PPG) reduced EFS-elicited responses and a combined blockade of both CSE and NO synthase (NOS) with, respectively, PPG and NG-nitro-L-arginine (L-NOARG), greatly reduced such relaxations. Endogenous H2S production rate was reduced by PPG, rescued by addition of GYY4137 and was not changed by L-NOARG. EFS and GYY4137 relaxations were also reduced by capsaicin-sensitive primary afferents (CSPA) desensitization with capsaicin and blockade of ATP-dependent K+ (KATP) channels, transient receptor potential A1 (TRPA1), transient receptor potential vanilloid 1 (TRPV1), vasoactive intestinal peptide/pituitary adenylyl cyclase-activating polypeptide (VIP/PACAP) and calcitonin gene-related peptide (CGRP) receptors with glibenclamide, HC030031, AMG9810, PACAP6–38 and CGRP8–37, respectively. These results suggest that H2S, synthesized by CSE, is involved in the inhibitory neurotransmission to the pig intravesical ureter, through an NO-independent pathway, producing smooth muscle relaxation via KATP channel activation. H2S also promotes the release of inhibitory neuropeptides, as PACAP 38 and/or CGRP from CSPA through TRPA1, TRPV1 and related ion channel activation.

Endothelin-1 contributes to endothelial dysfunction and enhanced vasoconstriction through augmented superoxide production in penile arteries from insulin-resistant obese rats: role of ETA and ETB receptors

We assessed whether endothelin‐1 (ET‐1) inhibits NO and contributes to endothelial dysfunction in penile arteries in a model of insulin resistance‐associated erectile dysfunction (ED).

Mantenimiento de la cadena del frío para las vacunas: una revisión sistemática

Objetivo: Los programas de inmunizacion sistematica dependen en gran medida del correcto mantenimiento y la manipulacion de las vacunas que se aplican, es decir, del perfecto mantenimiento de la cadena del frio. Por ello, nos propusimos realizar una revision sistematica de la literatura medica sobre la cadena del frio y las vacunas, con el objetivo de conocer las practicas diarias en los puntos de vacunacion. Metodos: Se efectuo una busqueda bibliografica en las principales bases medicas entre 1990 y 2005. Se incluyeron los estudios que, mediante encuesta y/o inspeccion a puntos de vacunacion, aportaban datos sobre: designacion de responsable sanitario, existencia de termometro de maximas y minimas, temperatura del frigorifico en el momento de la visita y control y registro de la temperatura. Para todas las variables se calculo la prevalencia media con su intervalo de confianza del 95%. Resultados: Se localizaron 377 articulos, se seleccionaron inicialmente 31 y se incluyeron 13 de ellos. El 72,21% de los puntos de vacunacion tenia un responsable de vacunas, pero solo el 61,43% de ellos conocian el rango optimo de temperaturas. Por otro lado, el 55% de estos puntos tenia un termometro de maxima y minima y solo el 26,88% realizaba controles y registros de temperaturas al menos una vez al dia. Conclusion: En las publicaciones incluidas en el estudio se detectan deficiencias importantes en el mantenimiento de la cadena del frio de las vacunas, que ponen en riesgo la efectividad y la eficiencia de los programas de inmunizacion.

Heterogeneity of the neuropeptide Y (NPY) contractile and relaxing receptors in horse penile small arteries.

The distribution of neuropeptide Y (NPY)‐immunorective nerves and the receptors involved in the effects of NPY upon electrical field stimulation (EFS)‐ and noradrenaline (NA)‐elicited contractions were investigated in horse penile small arteries. NPY‐immunoreactive nerves were widely distributed in the erectile tissues with a particularly high density around penile intracavernous small arteries. In small arteries isolated from the proximal part of the corpora cavernosa, NPY (30 nM) produced a variable modest enhancement of the contractions elicited by both EFS and NA. At the same concentration, the NPY Y1 receptor agonist, [Leu31, Pro34]NPY, markedly potentiated responses to EFS and NA, whereas the NPY Y2 receptor agonist, NPY(13–36), enhanced exogenous NA‐induced contractions. In arteries precontracted with NA, NPY, peptide YY (PYY), [Leu31, Pro34]NPY and the NPY Y2 receptor agonists, N‐acetyl[Leu28,31]NPY (24–36) and NPY(13–36), elicited concentration‐dependent contractile responses. Human pancreatic polypeptide (hPP) evoked a biphasic response consisting of a relaxation followed by contraction. NPY(3–36), the compound 1229U91 (Ile‐Glu‐Pro‐Dapa‐Tyr‐Arg‐Leu‐Arg‐Tyr‐NH2, cyclic(2,4′)diamide) and eventually NPY(13–36) relaxed penile small arteries. The selective NPY Y1 receptor antagonist BIBP3226 ((R)‐N2‐(diphenacetyl)‐N‐[(4‐hydroxyphenyl)methyl]D‐arginineamide) (0.3 μM) shifted to the right the concentration–response curves to both NPY and [Leu31, Pro34]NPY and inhibited the contractions induced by the highest concentrations of hPP but not the relaxations observed at lower doses. In the presence of the selective NPY Y2 receptor antagonist BIIE0246 ((S)‐N2‐[[1‐[2‐[4‐[(R,S)‐5,11‐dihydro‐6(6h)‐oxodibenz[b,e]azepin‐11‐y1]‐1‐piperazinyl]‐2‐oxoethyl]cyclo‐pentyl‐N‐[2‐[1,2‐dihydro–3,5 (4H)‐dioxo‐1,2‐diphenyl‐3H‐1,2, 4‐triazol‐4‐yl]ethyl]‐argininamide) (0.3 μM), the Y2 receptor agonists NPY(13–36) and N‐acetyl[Leu28,31]NPY (24–36) evoked potent slow relaxations in NA‐precontracted arteries, under conditions of nitric oxide (NO) synthase blockade. Mechanical removal of the endothelium markedly enhanced contractions of NPY on NA‐precontracted arteries, whereas blockade of the neuronal voltage‐dependent Ca2+ channels did not alter NPY responses. These results demonstrate that NPY can elicit dual contractile/relaxing responses in penile small arteries through a heterogeneous population of postjunctional NPY receptors. Potentiation of the contractions evoked by NA involve both NPY Y1 and NPY Y2 receptors. An NO‐independent relaxation probably mediated by an atypical endothelial NPY receptor is also shown and unmasked in the presence of selective antagonists of the NPY contractile receptors.

Impaired Endothelin Calcium Signaling Coupled to Endothelin Type B Receptors in Penile Arteries from Insulin-Resistant Obese Zucker Rats

INTRODUCTION Erectile dysfunction is considered as an early sign of subclinical vascular disease and endothelial dysfunction and a highly prevalent condition in diabetic patients. AIM The current study assessed whether impaired vascular effects of endothelin (ET)-1 may contribute to the vascular dysfunction of penile arteries from a rat model of insulin resistance. METHODS The effect of ETA and ETB receptor antagonists was assessed on the intracellular Ca(2+) [Ca(2+) ]i and contractile responses to ET-1 in penile arteries from obese Zucker rats (OZR) and lean Zucker rats (LZR), and ET receptor expression in the arterial wall was assessed by immunohistochemistry. MAIN OUTCOME MEASURE Changes in ET-1 [Ca(2+) ]i and vasoconstriction and ET receptor expression were evaluated in penile arteries from insulin-resistant rats. RESULTS ET-1-induced vasoconstriction was associated with a higher increase in smooth muscle [Ca(2+) ]i in penile arteries from OZR compared with LZR. Removal of the endothelium inhibited and enhanced contractions to the lowest and highest doses of ET-1, respectively, mainly in OZR. The selective ETA receptor antagonist BQ-123 inhibited ET-1 vasoconstriction and [Ca(2+) ]i response in both LZR and OZR. The ETB receptor antagonist BQ-788 had little effect in healthy arteries but markedly inhibited ET-1-induced increases in [Ca(2+) ]i and vasoconstriction in arteries from OZR. ETA receptors were located on the smooth muscle and endothelium of penile arteries, whereas ETB receptors were found on the arterial endothelium in LZR and OZR, and also on the smooth muscle in OZR, immunostaining for both receptors being higher in OZR. CONCLUSION Penile arteries from OZR exhibit an impaired ET-1 Ca(2+) signaling along with changes in the ET receptor profile. Thus, whereas ET-1 contraction and the associated [Ca(2+) ]i increase are mediated by smooth muscle ETA receptors in healthy arteries, ETB receptors contribute to contraction and are coupled to the augmented ET-1 [Ca(2+) ]i response under conditions of insulin resistance.

Cold chain maintenance in vaccines: a systematic review

OBJECTIVE Systematic immunization programmes mostly depend on the correct maintenance and manipulation of the vaccines to be used, i.e. perfect maintenance of the cold chain. Therefore, we decided to carry out a systematic review of the literature on the cold chain and vaccines, to identify daily practices in vaccine sites. METHODS A literature search was performed in the main medical databases for documents published between 1990 and 2005, including those performed by means of a survey and/or inspection of vaccine sites that provided the following data: a designated health officer, availability of a thermometer with maximums and minimums, refrigerator temperature at the time of the visit, and temperature control and registration. For all the variables, the mean prevalence was calculated with a 95% confidence interval. RESULTS Three hundred seventy-seven articles were found; 31 were initially selected and 13 were finally included. In 72.21% of the vaccine points, there was an officer responsible for the vaccines, but only 61.43% knew the optimal temperature range. Fifty-five percent of these points had a thermometer with maximums and minimums and only 26.88% carried out temperature controls and registrations at least once per day. CONCLUSION Important shortfalls were detected in cold chain maintenance in all selected articles, jeopardizing the effectiveness and efficiency of immunization programs.