Improvement of the Pour Plate Method by Separate Sterilization of Agar and Other Medium Components and Reduction of the Agar Concentration.

Although the pour plate method is widely employed in microbiological quality control, it has certain drawbacks, including having to melt the culture medium before seeding. In this study, the preparation of the culture medium was modified by using a lower concentration of agar (10 g/L), which was separated from the nutrients during sterilization. The new protocol was assessed in media frequently used in microbiological quality control of food, cosmetics, and pharmaceutical products, with tryptic soy agar (TSA), Sabouraud 4% dextrose agar (SDA), and violet red bile glucose agar (VRBG). In comparison with the conventionally produced media, the modifications significantly improved the growth of Saccharomyces cerevisiae in SDA, Staphylococcus aureus, Salmonella enterica subsp. enterica serovar Typhimurium, and Candida albicans in TSA and Escherichia coli ATCC 8739 and ATCC 25922 and S. Typhimurium in VRBG. The modified VRBG was also more selective for Pseudomonas aeruginosa. Regarding physicochemical properties, a significantly lower pH was observed in TSA and VRBG and lower strength values in TSA. Sterilizing agar separately from the other components of the medium and reducing the agar concentration to 10 g/L can improve microorganism growth and enhance the selectivity of differential media in the pour plate method. These modifications could facilitate the automation of this culture technique. IMPORTANCE In the era of rapid microbiological methods, there is a need to improve long-established culture techniques. Drawbacks of the pour plate method include having to melt each medium separately before seeding. For this technique, we demonstrate that separating the agar from the other components of commonly used media during sterilization and reducing the agar concentration to 10 g/L can enhance microbial growth. The new protocol could have advantages in routine laboratory practice because less agar is required and the same molten agar suspension can be used to prepare different media. Moreover, these modifications could facilitate the automation of the pour plate method.

Improvement of Mueller-Kauffman Tetrathionate-Novobiocin (MKTTn) enrichment medium for the detection of Salmonella enterica by the addition of ex situ-generated tetrathionate.

The detection of Salmonella in food is based on the use of a selective enrichment broth such as Muller-Kauffman Tetrathionate-Novobiocin (MKTTn), in which tetrathionate plays a key role by providing Salmonella with a growth advantage. As sodium tetrathionate is unstable, it is generated in situ by the addition of iodine (Lugol's solution) before seeding. This step is cumbersome as the solution is easily spilled, compromising the performance of the medium and hindering the work of technicians. The aim of this study was to optimize MKTTn broth by generating tetrathionate ex situ through an external reaction between iodine and thiosulphate followed by lyophilization. Quality control procedures were performed to compare the modified and original media, testing pure productivity (enrichment with 50-120 CFU of Salmonella Thyphimurium ATCC 14028 and Salmonella Enteritidis ATCC 13076 and plating on Xylose Lysine Deoxycholate agar, XLD), mixed productivity (50-120 CFU of Salmonella strains and Pseudomonas aeruginosa and Escherichia coli at ≥104 CFU and XLD plating) and selectivity (≥104 CFU of P. aeruginosa and Enterococcus faecalis and plating on Tryptone Casein Soy agar, TSA). The modified MKTTn medium (S/L) performed comparably with the original medium in terms of growth of both Salmonella strains (>300 colonies in XLD), alone or with P. aeruginosa and E. coli. Quantitative assays showed no statistically significant differences in the number of colonies grown on XLD after 10-5 dilution (p = 0.7015 with S. Thyphimurium ATCC 14028 and p = 0.2387 with S. Enteritidis ATCC 13076; ANOVA test). MKTTn medium (S/L) was also selective against E. coli (≤100 colonies) and E. faecalis (<10 colonies). These results suggest that adding tetrathionate as a lyophilisate (S/L) is a feasible alternative to the use of Lugol's solution for the preparation of MKTTn enrichment broth and does not affect the properties of the medium.

The malate sensing two-component system MaeKR is a non-canonical class of sensory complex for C4-dicarboxylates.

Microbial colonization of different environments is enabled to a great extent by the plasticity of their sensory mechanisms, among them, the two-component signal transduction systems (TCS). Here, an example of TCS plasticity is presented: the regulation of L-malate catabolism via malic enzyme by MaeRK in Lactobacillales. MaeKR belongs to the citrate family of TCS as the Escherichia coli DcuSR system. We show that the Lactobacillus casei histidine-kinase MaeK is defective in autophosphorylation activity as it lacks a functional catalytic and ATP binding domain. The cognate response regulator MaeR was poorly phosphorylated at its phosphoacceptor Asp in vitro. This phosphorylation, however, enhanced MaeR binding in vitro to its target sites and it was required for induction of regulated genes in vivo. Elucidation of the MaeR structure revealed that response regulator dimerization is accomplished by the swapping of α4-ß5-α5 elements between two monomers, generating a phosphoacceptor competent conformation. Sequence and phylogenetic analyses showed that the MaeKR peculiarities are not exclusive to L. casei as they are shared by the rest of orthologous systems of Lactobacillales. Our results reveal MaeKR as a non-canonical TCS displaying distinctive features: a swapped response regulator and a sensor histidine kinase lacking ATP-dependent kinase activity.

Trends in gastrointestinal bleeding in the Region of Valencia (2000-2005). Relationship to sales of nonsteroidal anti-inflammatory drugs and acid suppression medication

Objective Describe 2000-2005 time trends of prescription for NSAIDs, proton pump inhibitors (PPIs) and hospital admissions for gastrointestinal (GI) bleeding. Methods Time series analysis of gastrointestinal (GI) bleeding admission and drugs’ Defined Daily Dose per 1000 people per day (DDD/1000/day) in the Region of Valencia, Spain, from January 2000 to December 2005.ResultsDispensation of NSAIDs went from 42.7 DDD/1000 people/day in 2000 to 58.3 DDD/1000 people/day in 2005. During the same period, dispensation of PPIs went from 26.3 DDD/1000 people/day to 68.5 DDD/1000 people/day (both are statistically significant). The rate of hospitalisations for gastrointestinal bleeding during this period oscillated between 142 and 126 admission per 100 000 inhabitants/year. No year showed significant differences compared to 2000.ConclusionA substantial increase in the NSAID use from 2000 to 2005 was not accompanied by changes in GI bleeding hospitalisation rates in Valencia, but GI bleeding rates continued to be high, suggesting a need to improve NSAIDs use (AU)

Objetivo Describir las tendencias temporales durante el periodo 2000-2005 de la prescripción de AINE, inhibidores de la bomba de protones (IBP) y los ingresos hospitalarios por hemorragia gastrointestinal (GI).Métodos Análisis de series cronológicas de ingresos por hemorragia GI y de las dosis diarias definidas (DDD) de medicamento por cada 1.000 personas y día (DDD/1.000/día) en la Comunidad Valenciana desde enero de 2000 hasta diciembre de 2005.ResultadosLa dispensación de AINE ha aumentado desde 42,7 DDD/1.000/día en 2000 a 58,3 DDD/1.000/día, y la de IBP pasó de 26,3 DDD/1.000/día a 68,5 DDD/1000/día (ambos son cambios estadísticamente significativos). La tasa de ingresos por hemorragias GI durante este periodo pasó de 142 a 126 por cada 100.000 habitantes/año. En relación a 2000, ninguno de los años analizados muestra diferencias significativas. Conclusiones El aumento sustancial del uso de AINEs entre 2000 y 2005 no se vio acompañado de cambios en la tasa de ingresos hospitalarios en Valencia, pero la tasa de hemorragias GI siguieron siendo altas, lo que sugiere que es necesario mejorar la utilización de los AINE (AU)

Trends in gastrointestinal bleeding in the Region of Valencia (2000-2005). Relationship to sales of nonsteroidal anti-inflammatory drugs and acid suppression medication.

OBJECTIVE: To describe 2000-2005 time trends of prescription for NSAIDs, proton pump inhibitors (PPIs) and hospital admissions for gastrointestinal (GI) bleeding. METHODS: Time series analysis of gastrointestinal (GI) bleeding admission and drugs' Defined Daily Dose per 1000 people per day (DDD/1000/day) in the Region of Valencia, Spain, from January 2000 to December 2005. RESULTS: Dispensation of NSAIDs went from 42.7 DDD/1000 people/day in 2000 to 58.3 DDD/1000 people/day in 2005. During the same period, dispensation of PPIs went from 26.3 DDD/1000 people/day to 68.5 DDD/1000 people/day (both are statistically significant). The rate of hospitalisations for gastrointestinal bleeding during this period oscillated between 142 and 126 admission per 100 000 inhabitants/year. No year showed significant differences compared to 2000. CONCLUSION: A substantial increase in the NSAID use from 2000 to 2005 was not accompanied by changes in GI bleeding hospitalisation rates in Valencia, but GI bleeding rates continued to be high, suggesting a need to improve NSAIDs use.

«Lenguaje común» frente a independencia del patrocinador en la evaluación económica de medicamentos / No disponible

No disponible

Análogos de insulina: un pequeño paso para el hombre, un gran "peso" para la sociedad / Insulin analogues: a small step for mankind, a great “weight” for society"

No disponible

[Multicenter study on the prevalence of hyperglycemia among hospitalized patients with parenteral nutrition]. / Estudio multicéntrico de prevalencia de hiperglucemia en pacientes hospitalizados con nutrición parenteral.

OBJECTIVE: The aim of this cross-sectional national multicentric study was to determine the prevalence of hyperglycemia in patients with parenteral nutrition and to assess other clinical factors associated with this complication. METHOD: All Spanish hospital pharmacy services were invited to participate in the study. RESULTS: Twenty eight (28) pharmacy services agreed to participate. The study included 442 patients. The prevalence of hyperglycemia (plasma levels > 200 mg/dL) was 26.7%. Eighty four point two per cent of the patients received less than 3.5 mg/kg/minute of glucose, this infusion rate being considered as the safe threshold. In most patients, follow-up of glycemia was based on capillary blood determination with reactive strips and in 27.6% of the cases in which insulin was prescribed, it was added to the parenteral nutrition bag, in full or in part. No significant correlations were found between glycemia and the clinical factors studied (disorders, fever, medication), except for insulin. CONCLUSIONS: This national multicentric study of the prevalence of hyperglycemia among patients with parenteral nutrition, leaded by hospital pharmacists, was a joint effort aimed to better understand this metabolic complication. Findings are consistent with those reported by other authors and have allowed us to describe the current situation.

Estudio multicéntrico de prevalencia de hiperglucemia en pacientes hospitalizados con nutrición parenteral / Multicentric study on the prevalence of hyperglycemia among hospitalized patients with parenteral nutrition

Objetivo: El objetivo de este estudio nacional transversal multicéntricofue evaluar la prevalencia de hiperglucemia en pacientescon nutrición parenteral y evaluar otros factores clínicos relacionadoscon esta complicación.Método: Se ofertó participar en el estudio a todos los serviciosde farmacia de los hospitales españoles.Resultados: Accedieron a participar 28 servicios de farmacia.El estudio incluyó 442 pacientes. La prevalencia de hiperglucemia(valores séricos > 200 mg/dL) se situó en el 26,7%. El 84,2% depacientes recibieron menos de 3,5 mg/kg/minuto de glucosa,velocidad de infusión postulada como umbral de seguridad. Elseguimiento mayoritario de la glucemia fue mediante determinaciónen sangre capilar con tiras reactivas y el 27,6% de los casosen que se pautó insulina, esta estaba aditivada en la bolsa de nutriciónparenteral, total o parcialmente. No se pudieron demostrarcorrelaciones significativas entre la glucemia y los factores clínicosestudiados (patologías, fiebre, medicación), pero sí con la insulina.Conclusiones: Este estudio multicéntrico nacional sobre laprevalencia de hiperglucemia en pacientes con nutrición parenteral,liderado por farmacéuticos de hospital, constituye un esfuerzointegrado para conocer mejor esta complicación metabólica. Losdatos descritos se sitúan dentro de los aportados por otros autoresy nos han permitido caracterizar la situación actual

Objective: The aim of this cross-sectional national multicentricstudy was to determine the prevalence of hyperglycemia inpatients with parenteral nutrition and to assess other clinical factorsassociated with this complication.Method: All Spanish hospital pharmacy services were invitedto participate in the study.Results: Twenty eight (28) pharmacy services agreed to participate.The study included 442 patients. The prevalence ofhyperglucemia (plasma levels > 200 mg/dL) was 26.7%. Eightyfour point two per cent of the patients received less than 3,5mg/kg/minute of glucose, this infusion rate being considered asthe safe threshold. In most patients, follow-up of glycemia wasbased on capillary blood determination with reactive strips and in27.6% of the cases in which insulin was prescribed, it was addedto the parenteral nutrition bag, in full or in part. No significantcorrelations were found between glycemia and the clinical factorsstudied (disorders, fever, medication), except for insulin.Conclusions: This national multicentric study of the prevalenceof hyperglycemia among patients with parenteral nutrition,leaded by hospital pharmacists, was a joint effort aimed to betterunderstand this metabolic complication. Findings are consistentwith those reported by other authors and have allowed us todescribe the current situation

Evaluation of enzyme-linked immunoassays for the determination of chloroacetanilides in water and soils.

Reliable and sensitive indirect ELISAs for the quantitative determination of metolachlor, alachlor, and acetochlor were developed. Each herbicide was conjugated to a carrier protein via thioether linkage, and the product was used either as an immunogen or to prepare coating conjugates. The suitability of using the same chemical strategy to raise polyclonal antibodies against chloroacetanilides structurally related compounds and their metabolites is discussed. Under best conditions, detection limits of 0.06, 0.3, and 0.4 microg/L for metolachlor, alachlor, and acetochlor were reached, respectively. The optimized ELISAs were also highly specific, showing little or no cross-reactivity to other similar compounds. Immunoassays were used as a toolto determine critical chloroacetanilide herbicides in water and soil samples without purification steps. The excellent recoveries obtained (mean value ranging between 90% and 98%) confirm the potential of this approach to control these herbicides in the environment being applied as a "screening" method either for field monitoring or laboratory.

Impaired endothelium-dependent vascular relaxation in patients with hypercholesterolemia extends beyond the muscarinic receptor.

Patients with hypercholesterolemia have impaired endothelium-dependent vasodilation. However, previous human studies have invariably used muscarinic agents to assess endothelial function. The purpose of this investigation was to determine whether impaired endothelium-dependent vasodilation of hypercholesterolemic patients is related to a specific and isolated defect of the muscarinic receptor, or to a broader abnormality of the endothelial cells. The forearm vascular responses to the endothelium-dependent agents acetylcholine (7.5, 15, and 30 micrograms/min) and substance P (1, 2, and 4 pmol/min), and to the direct smooth muscle dilator sodium nitroprusside (0.8, 1.6, and 3.2 micrograms/min) were studied in 16 hypercholesterolemic patients (8 men and 8 women; age [mean +/- SD] 50 +/- 7 years; serum cholesterol > 250 mg/dl) and 16 normal volunteers (8 men and 8 women; age 47 +/- 8 years; serum cholesterol < 200 mg/dl). Drugs were infused into the brachial artery and the response of the forearm vasculature was measured by strain-gauge plethysmography. The vasodilator response to acetylcholine was reduced in hypercholesterolemic patients compared with normal controls; at the highest dose (30 micrograms/min) the increase in forearm blood flow was 13.5 +/- 7 ml/min/100 ml in controls and 7.54 +/- 6 in patients (p < 0.05). The response to substance P was also blunted in hypercholesterolemic patients; at the highest dose (4 pmol/min), the increase in forearm blood flow was 12.1 +/- 5 ml/min/100 ml in controls and 7.6 +/- 4 in patients (p < 0.03). A significant correlation was found between the highest blood flow responses with acetylcholine and with substance P (r = 0.58; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Contribution of endothelium-derived nitric oxide to exercise-induced vasodilation.

BACKGROUND: Endothelium-derived nitric oxide is an important modulator of resting vascular tone in animals and humans. However, the contribution of nitric oxide to exercise-induced vasodilation is unknown. METHODS AND RESULTS: The effect of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of nitric oxide synthesis, on exercise-induced vasodilation was studied in 18 healthy subjects (mean +/- SD, 40 +/- 10 years; 10 women). Acetylcholine was used to test the efficacy of L-NMMA in inhibiting stimulation of nitric oxide synthesis and sodium nitroprusside to test the specificity of L-NMMA in inhibiting endothelium-dependent vasodilation. Intermittent handgrip exercise and infusions of acetylcholine and sodium nitroprusside were performed during intra-arterial infusion of 5% dextrose (control) and L-NMMA (4 to 16 mumol/min). Forearm blood flow was determined by strain-gauge plethysmography. Forearm oxygen extraction was measured from arterial and venous oxygen saturations. In a separate study, 10 subjects performed exercise during infusions of 5% dextrose, L-arginine (the substrate for nitric oxide production), and D-arginine (the stereoisomer that is not a substrate for nitric oxide production). L-NMMA reduced exercise blood flow by 7 +/- 13% (P = .04), increased exercise resistance by 18 +/- 20% (P = .02), and increased exercise oxygen extraction by 16 +/- 17% (P < .001). The degree of inhibition of acetylcholine-induced vasodilation with L-NMMA correlated positively with the degree of reduction in exercise blood flow (r = .55, P = .02). The highest dose of L-NMMA (16 mumol/min) produced the greatest effect; exercise blood flow was reduced by 11 +/- 14% (P = .03), and vascular resistance increased by 26 +/- 23% (P = .005). L-NMMA did not affect the forearm vasodilation produced by sodium nitroprusside. Exercise blood flow, resistance, and oxygen extraction were not significantly modified by infusions of either L- or D-arginine. CONCLUSIONS: Inhibition of nitric oxide synthesis reduces exercise-induced vasodilation in the human forearm, indicating that nitric oxide plays a role in exercise-induced vasodilation. Increased availability of nitric oxide substrate does not enhance exercise-induced vasodilation in healthy subjects. These findings have important implications for disease states in which endothelium-derived nitric oxide production is impaired.

Effect of antioxidant vitamins on low density lipoprotein oxidation and impaired endothelium-dependent vasodilation in patients with hypercholesterolemia.

OBJECTIVES: The aims of this study were to determine whether antioxidant vitamins could reduce the susceptibility of low density lipoprotein (LDL) to oxidation and improve endothelium-dependent vasodilator responsiveness in patients with hypercholesterolemia. BACKGROUND: Animals and humans with hypercholesterolemia have exhibited impaired endothelium-dependent vasodilation. In vitro studies suggest that oxidatively modified LDL can impair nitric oxide production. METHODS: Forearm blood flow was measured with strain gauge plethysmography and brachial artery drug infusions in 19 patients, aged 52 +/- 9 years, with hypercholesterolemia (mean +/- SD total cholesterol 283 +/- 22 mg/dl, LDL 197 +/- 31 mg/dl) and in 14 subjects, aged 48 +/- 8 years, with normal cholesterol levels (total cholesterol 169 +/- 20 mg/dl, LDL 102 +/- 25 mg/dl). Acetylcholine (7.5, 15 and 30 micrograms/min) was utilized as an endothelium-dependent vasodilator, and sodium nitroprusside (0.8, 1.6 and 3.2 micrograms/min) was used to test endothelium-independent vasodilation. Oxidative susceptibility of LDL was measured by a spectrophotometric assay of conjugated diene production after the addition of copper chloride. Hypercholesterolemic patients then received daily antioxidant vitamin supplements (beta-carotene [30 mg], ascorbic acid [vitamin C] [1,000 mg], vitamin E [800 IU]) for 1 month, with repeat measurement of both forearm blood flow responsiveness to the same agonists and LDL oxidizability. RESULTS: The maximal flow in response to acetylcholine was impaired in patients compared with that in normal subjects (9.8 +/- 7.8 vs. 15.9 +/- 8.1 ml/min per 100 ml, p = 0.03), with similar maximal flow responses to sodium nitroprusside (9.5 +/- 4.2 vs. 9.0 +/- 2.8 ml/min per 100 ml, p = 0.72). After 1 month of vitamin therapy, the onset of LDL oxidation was prolonged over baseline measurements by 71 +/- 67%, and the maximal rate of oxidation was decreased by 26 +/- 25% (both p < 0.001). However, the maximal forearm blood flow response to acetylcholine remained unchanged from baseline values (maximal flow after acetylcholine 9.0 +/- 6.2 vs. 9.8 +/- 7.8 ml/min per 100 ml, p = 0.57). This study had 80% power (alpha = 0.05) to exclude a 45% increase over baseline value in acetylcholine-stimulated flow during vitamin therapy. CONCLUSIONS: Although 1 month of administration of antioxidant vitamin supplements in hypercholesterolemic patients reduced the susceptibility of LDL to oxidation, impairment in endothelial function remained unaltered. The use of nonvitamin antioxidants or concomitant reduction in LDL levels, as well as more sensitive techniques for measuring vascular responsiveness, may be required to show a beneficial effect on endothelial vasodilator function.

Impaired endothelium-dependent vasodilation in patients with essential hypertension: evidence that the abnormality is not at the muscarinic receptor level.

OBJECTIVES: The purpose of this study was to determine whether the impaired endothelium-dependent vasodilation of hypertensive patients is related to a specific defect of the muscarinic receptor or to a broader abnormality of the vascular endothelium. BACKGROUND: Patients with essential hypertension have abnormal endothelium-dependent vasodilator response to acetylcholine. However, whether this results from an isolated dysfunction of the endothelial cell muscarinic receptor is unknown. METHODS: The responses of the forearm vasculature to acetylcholine and substance P (endothelium-dependent agents acting on different receptors) and to sodium nitroprusside (a direct dilator of vascular smooth muscle) were studied in eight hypertensive patients (six men, two women; mean age [+/- SD] 50 +/- 12 years) and eight normal control subjects (four men, four women; mean age 49 +/- 9 years). To determine the nitric oxide contribution to substance P-induced vasodilation, the vascular responses to substance P were also measured after inhibition of nitric oxide synthesis with NG-monomethyl-L-arginine. Drugs were infused into the brachial artery, and forearm blood flow was measured by strain gauge plethysmography. RESULTS: The response to acetylcholine was significantly blunted in hypertensive patients (highest blood flow [mean +/- SD] 8.4 +/- 4 vs. 13.8 +/- 4 ml/min per 100 ml in control subjects, p < 0.03). Similarly, the vasodilator effect of substance P was significantly reduced in hypertensive patients (highest blood flow [mean +/- SD] 8.8 +/- 4 vs. 13.9 +/- 4 ml/min per 100 ml in control subjects, p < 0.03). A significant correlation was found between the maximal blood flow with acetylcholine and that with substance P (r = 0.68, p < 0.004). The vasodilator response to sodium nitroprusside was similar in patients and control subjects. The nitric oxide contribution to substance P-induced vasodilation was reduced in hypertensive patients, such that the responses to substance P measured during infusion of NG-monomethyl-L-arginine were not significantly different between the two groups. CONCLUSIONS: These findings indicate that the endothelial abnormality of patients with essential hypertension is not restricted to the muscarinic cell receptor.

Investigation of decreased availability of nitric oxide precursor as the mechanism responsible for impaired endothelium-dependent vasodilation in hypercholesterolemic patients.

OBJECTIVES: The purpose of this study was to determine whether the impaired endothelium-dependent vasodilation of hypercholesterolemic patients is due to decreased availability of L-arginine, the substrate for nitric oxide. BACKGROUND: Patients with hypercholesterolemia have impaired endothelium-dependent vasodilation that is related to a defect in the endothelium-derived nitric oxide system. However, the precise location of this abnormality has not been determined. METHODS: The study included 12 hypercholesterolemic patients (6 men, 6 women; 52 +/- 9 years old; serum cholesterol > 240 mg/dl) and 15 normal volunteers (8 men, 7 women; 50 +/- 6 years old; serum cholesterol < 210 mg/dl). The forearm vascular responses to intraarterial infusion of acetylcholine, an endothelium-dependent vasodilator (7.5, 15, 30 micrograms/min), and sodium nitroprusside, a direct smooth muscle dilator (0.8, 1.6, 3.2 micrograms/min) were studied before and during infusion of L- or D-arginine (a stereoisomer of arginine that is not a nitric oxide precursor). RESULTS: The response to acetylcholine was lower in hypercholesterolemic patients than in control subjects. However, no significant difference was observed with sodium nitroprusside infusion. L-Arginine augmented the response to acetylcholine in normal subjects (maximal blood flow increased from 14.4 +/- 7 to 18.9 +/- 10 ml/min per 100 ml, p < 0.002). In contrast, in the hypercholesterolemic patients, only a mild but not significant improvement in the response to acetylcholine was observed with the infusion of L-arginine (maximal blood flow increased from 6.8 +/- 4 to 8.4 +/- 5 ml/min per 100 ml; p = 0.16); however, a similar mild but not significant change was also observed with D-arginine (maximal blood flow increased from 6.8 +/- 4 to 8.3 +/- 4 ml/min per 100 ml, p = 0.07). L-Arginine did not modify the response to sodium nitroprusside in either group. CONCLUSIONS: The augmentation of endothelium-dependent vasodilation by L-arginine, the nitric oxide precursor, is defective in hypercholesterolemic patients. This supports the concept of an abnormal endothelium-derived nitric oxide system in hypercholesterolemia and indicates that decreased availability of nitric oxide substrate is not responsible for the impaired endothelial function in this condition.

The role of nitric oxide in endothelium-dependent vasodilation of hypercholesterolemic patients.

BACKGROUND: Patients with hypercholesterolemia have a reduced response to endothelium-dependent vasodilators. However, the regulatory function of the endothelium on vascular tone is mediated through the release of several vasoactive substances; therefore, a reduced response to endothelium-dependent agents does not identify which of the factors released by the endothelium is involved in this abnormality. METHODS AND RESULTS: To investigate the role of nitric oxide in the endothelium-dependent vasodilation in hypercholesterolemia, we studied the effect of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of endothelial nitric oxide synthesis, on basal vascular tone and on the responses to acetylcholine, an endothelium-dependent vasodilator, and to sodium nitroprusside, a direct smooth muscle dilator. The study included 33 hypercholesterolemic patients (17 men; 51 +/- 8 years; plasma cholesterol, > or = 240 mg/dL) and 23 normal controls (12 men; 48 +/- 7 years; plasma cholesterol, < 210 mg/dL). Drugs were infused into the brachial artery, and the response of the forearm vasculature was measured by strain-gauge plethysmography. Basal blood flow and vascular resistance were similar in hypercholesterolemic patients and normal controls (3.1 +/- 1 versus 2.6 +/- 0.8 mL/min per 100 mL and 32.1 +/- 13 versus 36.1 +/- 12 mm Hg/mL-1.min-1.100 mL-1, respectively). The reduction in basal blood flow and increase in vascular resistance produced by L-NMMA were not significantly different between the two groups. L-NMMA markedly blunted the response to acetylcholine in normals (maximum flow decreased from 16.4 +/- 8 to 7.0 +/- 3; P < .005); however, the arginine analogue did not significantly modify the response to acetylcholine in the hypercholesterolemic patients (maximum flow, 11.1 +/- 8 versus 10.0 +/- 8). L-NMMA did not modify the vasodilator response to sodium nitroprusside in either controls or patients. CONCLUSIONS: These findings indicate that hypercholesterolemic patients have a defect in the bioactivity of nitric oxide that may explain their impaired endothelium-dependent vascular relaxation.

Role of endothelium-derived nitric oxide in the abnormal endothelium-dependent vascular relaxation of patients with essential hypertension.

BACKGROUND: Patients with essential hypertension have abnormal endothelium-dependent vasodilation. Because the endothelium exerts its action on the vascular smooth muscle through the release of several substances, it is important to identify which of these factors is involved in the abnormal response of hypertensive arteries. METHODS AND RESULTS: To investigate the role of endothelium-derived nitric oxide in this abnormality, we studied the vascular effect of the arginine analogue NG-monomethyl-L-arginine, an inhibitor of the endothelial synthesis of nitric oxide, under baseline conditions and during infusion of acetylcholine, an endothelium-dependent vasodilator, and sodium nitroprusside, a direct smooth muscle dilator. The study included 11 hypertensive patients (seven men; age, 46.5 +/- 9 years) and 10 normal control subjects (seven men; age, 45.7 +/- 7 years). Drugs were infused into the brachial artery, and the response of the forearm vasculature was measured by strain-gauge plethysmography. Basal blood flow was similar in normal control subjects and hypertensive patients (2.97 +/- 0.7 versus 2.86 +/- 1.1 mL.min-1.100 mL-1, respectively). NG-monomethyl-L-arginine produced a significantly greater decrease in blood flow in control subjects than in patients (1.08 +/- 0.6 versus 0.32 +/- 0.4 mL.min-1.100 mL-1; p < 0.004). The vasodilator response to acetylcholine was reduced in patients compared with control subjects (maximum flow, 8.2 +/- 4 versus 16.4 +/- 8 mL.min-1.100 mL-1; p < 0.001). NG-monomethyl-L-arginine blunted the vasodilator response to acetylcholine in control subjects (maximum flow decreased from 16.4 +/- 8 to 7.01 +/- 3 mL.min-1.100 mL-1; p < 0.004); however, the arginine analogue did not significantly alter the response to acetylcholine in hypertensive patients (maximum flow, 8.2 +/- 4 versus 8.01 +/- 5 mL.min-1.100 mL-1). NG-monomethyl-L-arginine did not modify the vasodilator response to sodium nitroprusside in either control subjects or patients. CONCLUSIONS: These findings indicate that patients with essential hypertension have a defect in the endothelium-derived nitric oxide system that may at least partly account for both the increased vascular resistance under basal conditions and the impaired response to endothelium-dependent vasodilators.

Effect of increased availability of endothelium-derived nitric oxide precursor on endothelium-dependent vascular relaxation in normal subjects and in patients with essential hypertension.

BACKGROUND: Patients with essential hypertension have a deficit in the endothelium-derived nitric oxide system that results in impaired endothelium-dependent vascular relaxation. The objective of this study was to determine whether this abnormality is caused by a deficiency of substrate for nitric oxide synthesis. METHODS AND RESULTS: The vascular responses to acetylcholine (an endothelium-dependent vasodilator infused at 7.5, 15, and 30 micrograms/min) and sodium nitroprusside (a direct smooth muscle dilator infused at 0.8, 1.6, and 3.2 micrograms/min) were studied during combined administration of dextrose 5% or L-arginine (substrate for nitric oxide synthesis infused at 40 mumol/min) in 12 normal control subjects (seven men and five women; age, 49.3 +/- 7 years) and 14 hypertensive patients (nine men and five women; age, 48.4 +/- 7 years). In addition, the effect of D-arginine (stereoisomer of arginine that is not a precursor of nitric oxide) on the vascular responses to acetylcholine was studied in eight normal control subjects and seven hypertensive patients. Drugs were infused into the brachial artery, and the response of the forearm vasculature was measured by strain gauge plethysmography. The vasodilator response to acetylcholine was significantly blunted in hypertensive patients compared with normal control subjects (maximum flow, 8.9 +/- 5 versus 15.7 +/- 6 mL.min-1.100 mL-1, respectively; p < 0.007); however, no difference was observed in the response to sodium nitroprusside (11.4 +/- 6 and 11.7 +/- mL.min-1.100 mL-1, respectively). L-Arginine did not significantly change basal blood flow or vascular resistance in either group. In normal control subjects, the infusion of L-arginine significantly augmented the vasodilator response to acetylcholine (maximum flow, 15.7 +/- 6 versus 21.4 +/- 8 mL.min-1.100 mL-1 before and after L-arginine, respectively; p < 0.001). In contrast, in hypertensive patients, the infusion of L-arginine did not alter the response to acetylcholine (maximum flow, 8.9 +/- 5 and 8.4 +/- 4 mL.min-1.100 mL-1 before and after L-arginine, respectively). The administration of L-arginine did not modify the response to sodium nitroprusside in either group. Similarly, the infusion of D-arginine did not alter the response to acetylcholine in either group. CONCLUSIONS: In normal humans, availability of substrate for production of nitric oxide is a rate-limiting step for endothelium-dependent vascular relaxation. In contrast, increased availability of nitric oxide precursor does not modify endothelium-mediated vasodilation in hypertensive patients. These findings provide further evidence of a defect in the endothelium-derived nitric oxide system in hypertension and indicate that this abnormality is not related to decreased availability of substrate for nitric oxide production.

[3 possible sources of microbiologic contamination in the preparation of formulations for parenteral nutrition]. / Estudio de tres potenciales fuentes de contaminación microbiológica en la elaboración de nutriciones parenterales.

It is well known that the microbiological control of "all in one" nutritional preparations is difficult. In this work we evaluated and compared the potential contaminants that may be present in the process of manufacturing in a Centralized Unit of Parenteral Nutrition. The study has been centered on the microbiological contamination that may be introduced by the technician, by the raw materials, and that existing in the work area. A microbiological contact technique was used. The results obtained showed that the main microbiological contaminants are introduced by the technician when not observing strict aseptic measures. Another source of contamination is represented by PVC bags when they are manipulated in the pre-sterile area and are not sprayed with alcohol 70 degrees. Therefore, PVC contamination arises from the hands of the technician. Significant differences in contamination between hands washed with germicidal soap and sterile gloves and between clean and sterile surgical dressing could not be demonstrated.