External fixation in intra-articular fractures of the calcaneus: Is it a valid option as definitive treatment?

INTRODUCTION: The therapeutic management of calcaneal fractures is currently a major source of controversy in the literature. There is no consensus on the need to treat these injuries conservatively or surgically, nor on the criteria for deciding one option or the other. Although the gold standard has classically been the open approach and osteosynthesis, there are currently minimally invasive techniques that also report good results. Our objective is to present our results and experience with the MBA® Orthofix external fixator in a series of cases of calcaneal fractures. METHODS: We performed a retrospective observational study in our center, between the years 2019 and 2021, of Sanders types II-IV calcaneal fractures operated with MBA® Orthofix external fixator. We recorded a total of 38 patients, 42 fractures. We registered demographic information, intraoperative, postoperative, radiological and functional parameters, using the American Orthopedic Foot and Ankle Society (AOFAS), Manchester-Oxford Foot Questionnaire (MOXFQ), EQ-5D and VAS scales. RESULTS: A total of 26 men and 12 women were included, and the median age was 38 years. Mean follow-up was 24,4 months (6, 8-40, 1). The average time to surgery was 7 days and partial loading was started at 2.5 weeks after external fixation, which was removed at 9.2 weeks. The average Böhler angle correction was 7, 4°, Gissane - 12,2°, length 2 mm and calcaneal width was reduced by 5 mm. We recorded two superficial infections, one peroneal entrapment and three subtalar arthrodesis due to post-traumatic osteoarthritis. The AOFAS obtained was 79.1 + / - 15.7 points, MOXFQ 20.1 + / - 16.1 points, EQ-5D 0.84 + / - 0.2 and VAS 3.3 + / - 1.9. CONCLUSION: The external fixator is an excellent surgical alternative for complex articular fractures of the calcaneus, obtaining clinical and radiological results comparable to other osteosynthesis techniques and significantly reducing soft tissue complications.

BCN Checkpoint: same-day confirmation of reactive HIV rapid test with Point Of Care HIV-RNA accelerates linkage to care and reduces anxiety.

BACKGROUND: The introduction in 2006 of the rapid HIV test by BCN Checkpoint in a non-clinical setting has been a successful step forwards in the uptake of testing. Nevertheless, HIV serostatus should be reported as HIV positive only when a reactive result has been tested again using a different assay (WHO guidelines 2015). The standard confirmation test has been the Western Blot (WB) test. However confirmation results take around 7 days to come back. AIMS: This study explores the possibility of Point of Care PCR testing for a same-day confirmation. MATERIALS AND METHODS: Between March 2015 and September 2016 a POC PCR test (Xpert® HIV-1 Qual) was performed in parallel to the Western Blot test after a reactive HIV rapid test (Alere Determine™ HIV-1/2 Ag/Ab Combo and Alere™ HIV Combo). HIV confirmed positive cases received emotional support by peers, were informed and prepared for treatment initiation and rapidly linked to HIV clinic. RESULTS: During the study period 11 455 tests were performed to 7163 clients. A total of 249 reactive rapid HIV tests were found. For analysis a total of 33 cases were excluded due to the lack of PCR and/or WB test. Results of comparison of the 216 cases showed 194 concordant positive confirmations and 14 concordant negative results. In three cases PCR was positive and WB negative. In five cases PCR was negative and WB positive. CONCLUSION: The POC PCR assay is easy to use and feasible in a community-based center. Reducing time for confirmation to 90 min has been possible in 91.2% (197/216) of cases with positive PCR result. In cases of a negative PCR result an additional test (WB, Elisa or PCR quantitative) was needed to distinguish false positive results (6.5%) from viral load results below level of detection (2.3%). Clients expressed satisfaction with same-day confirmation and less anxiety.

Atom-scale compositional distribution in InAlAsSb-based triple junction solar cells by atom probe tomography.

The analysis by atom probe tomography (APT) of InAlAsSb layers with applications in triple junction solar cells (TJSCs) has shown the existence of In- and Sb-rich regions in the material. The composition variation found is not evident from the direct observation of the 3D atomic distribution and because of this a statistical analysis has been required. From previous analysis of these samples, it is shown that the small compositional fluctuations determined have a strong effect on the optical properties of the material and ultimately on the performance of TJSCs.

[Long-term clinical and radiological results of metatarsophalangeal resection arthroplasty in patients with large forefoot deformities]. / Resultados clínicos y radiológicos a largo plazo de la artroplastía de resección metatarsofalángica en pacientes con grandes deformidades del antepié.

INTRODUCTION: metatarsophalangeal resection arthroplasty is considered a salvage surgical procedure able to improve the quality of life of patients with major forefoot deformities. MATERIAL AND METHODS: a retrospective observational study of 31 patients (36 feet) with major forefoot deformities operated at our institution was performed. Thirty two feet required additional surgery involving the first ray, most of them (72.2%) through MTP joint fusion. The mean follow-up period was 10.3 ± 4.6 years. Most patients were women (87.1%), the mean age was 74.2 ± 11.5 years. RESULTS: at the final follow-up, mean AOFAS score was 77.9 ± 10.2 points and mean MOxFQ score was 18.3 ± 8.3 points. Visual analog scale (VAS) for pain improved significantly from 7.5 ± 1.2 points to 3.4 ± 2.1 points on average. Good clinical results were also reported on ability to put on shoes comfortably. The mean resection arthroplasty spaces at the end of the study were 1.3, 1.8, 2.5 and 4.4 mm, for second to fifth rays, respectively. The mean sizes of remodeling osteophytes at the end of the study were 1.6, 1.4, 1.1 and 0.7 mm, respectively. Significant improvement was also achieved in the hallux valgus angle (HVA) and intermetatarsal angle (IMA) at the end of the study. CONCLUSION: in our experience, metatarsophalangeal resection arthroplasty continues to be a valid choice in patients with major forefoot deformities, with satisfactory long-term clinical and radiographic results.

INTRODUCCIÓN: la artroplastía de resección metatarsofalángica se considera un procedimiento quirúrgico de salvamento capaz de mejorar la calidad de vida de pacientes con deformidades importantes en el antepié. MATERIAL Y MÉTODOS: se realizó un estudio observacional retrospectivo de 31 pacientes (36 pies) con deformidades importantes en el antepié operados en nuestra institución. Treinta y dos pies requirieron cirugía adicional que involucró el primer metatarsiano, la mayoría de ellos (72.2%) a través de la fusión de la articulación metatarsofalángica. El período de seguimiento promedio fue 10.3 ± 4.6 años. La mayoría de los pacientes fueron mujeres (87.1%), con una edad promedio de 74.2 ± 11.5 años. RESULTADOS: en la última visita de seguimiento, la puntuación AOFAS promedio fue de 77.9 ± 10.2 puntos y la puntuación MOxFQ promedio fue de 18.3 ± 8.3 puntos. La escala visual analógica (EVA) para el dolor mejoró significativamente, pasando de 7.5 ± 1.2 puntos a 3.4 ± 2.1 puntos de media. También se constataron buenos resultados clínicos en cuanto a la capacidad de calzarse con comodidad. Los espacios de resección promedio al final del estudio fueron 1.3, 1.8, 2.5 y 4.4 mm para el segundo al quinto radio, respectivamente. Los tamaños promedio de los osteofitos por remodelación al final del estudio fueron de 1.6, 1.4, 1.1 y 0.7 mm, respectivamente. También se logró una mejora significativa en el ángulo de hallux valgus (AHV) y en el ángulo intermetatarsiano (IMA) al final del estudio. CONCLUSIÓN: en nuestra experiencia, la artroplastía de resección metatarsofalángica sigue siendo una opción válida en pacientes con deformidades graves del antepié, con resultados clínicos y radiográficos satisfactorios a largo plazo.

BCN Checkpoint, a community-based centre for men who have sex with men in Barcelona, Catalonia, Spain, shows high efficiency in HIV detection and linkage to care.

OBJECTIVES: We assessed the efficiency of BCN Checkpoint in detecting new cases of HIV infection and efficiently linking newly diagnosed individuals to care. METHODS: This study analysed during 2007-2012 the number of tests performed and the number of persons tested in BCN Checkpoint, the HIV prevalence, global and in first visits, the capacity of HIV detection compared to the reported cases in MSM in Catalonia, and the linkage to care rate. RESULTS: During the six years a total of 17.319 tests were performed and 618 HIV-positive cases were detected. Median prevalence of clients who visited the centre for the first time was 5.4% (4.1-5.8). BCN Checkpoint detected 36.3% (35.0-40.4) of all reported cases in MSM during 2009-2011. Linkage to care was achieved directly in 90.5% of the cases and only 2.4% of cases were lost to follow-up. CONCLUSIONS: A community-based centre, addressed to a key population at risk, can be less effort consuming (time and funding) and show high efficiency in HIV detection and linkage to care.

[Failed back surgery, spinal cord stimulation and pregnancy: presentation of a case]. / Descripción de un caso de síndrome de cirugía fallida de espalda, estimulación medular y embarazo.

Spinal cord stimulation is increasingly used to manage chronic pain syndromes, such as complex regional pain syndrome, chronic back pain, refractory angina pectoris or peripheral vascular diseases, which are unresponsive to other common less aggressive treatment methods. The early use of this technique in the aforementioned diseases makes it suitable in young women of childbearing age and who wish to become pregnant. We report the case of a 33-year-old woman who became pregnant 4 months after having undergone posterior cord stimulation, and we review the approach to this situation and the perioperative management during the perinatal period.

Modelling the simultaneous chiral separation of a group of drugs by electrokinetic chromatography using mixtures of cyclodextrins.

Two mixtures of neutral cyclodextrins (CDs) were used in Electrokinetic Chromatography (EKC) to model and optimize the simultaneous enantiomeric separation of a group of seven drugs. Heptakis(2,6-di-O-methyl)-ß-CD (DM-ß-CD) combined with methyl-γ-CD (M-γ-CD) or with carboxyethyl-γ-CD (CE-γ-CD) was employed in a 25 mM formate buffer at pH 3.0 to have the drugs studied positively charged. Dubsky's model was applied to calculate the enantiomer effective electrophoretic mobilities for each combination of CDs at different averaged molar fractions and total CDs concentrations. The most adequate averaged molar fraction and total CDs concentration in terms of the simultaneous enantiomeric separation of the drug mixture were predicted by the model and results were experimentally corroborated. The model also foresaw interesting effects, derived from the combination of DM-ß-CD with M-γ-CD or with CE-γ-CD, on the individual chiral separation of some of the drugs studied. The observed reversal of the migration order for some compounds when changing the total CDs concentration was also predicted and the model showed its potential even at concentrations out of the experimental range of CD concentrations experimentally employed. The use of an averaged molar fraction of 0.8 for DM-ß-CD at a total CDs concentration of 40 mM in the DM-ß-CD/CE-γ-CD system predicted by the model enabled the simultaneous enantiomeric separation of six of the drugs studied (except verapamil) with resolutions ranging from 0.6 to 4.0.

[Impact of COVID-19 pandemic confinement on musculoskeletal pain and quality of life]. / Impacto del confinamiento por la pandemia COVID-19 en el dolor musculoesquelético y la calidad de vida.

INTRODUCTION: in March 2020, lockdown was established in Spain because of the COVID-19 pandemic. The aim of this study is to assess its impact on pain and quality of life in patients with musculoskeletal pain. MATERIAL AND METHODS: prospective study including 490 individuals grouped in: 140 people without pain, 140 people with musculoskeletal pain but without any related pathology diagnosed, 140 patients diagnosed for a musculoskeletal condition and 70 patients in surgical waiting list (SWL) for a musculoskeletal condition. Data regarding pain, physical activity and quality of life (EuroQol-5D) was collected at the beginning of lockdown and one year after (March 2021). RESULTS: mean age was 53 ± 17.5 years old (18-88) and 51.3% were women. Patients in SWL referred significantly more pain than the rest of groups (p < 0.001), with a score in the visual analogue scale of 6.3 ± 1.9. Groups 3 and 4 suffered a significant increase of their pain from 2020 to 2021 (p < 0.001), while decreasing in group 2 (p < 0.001). Analgesics intake grew from 2020 to 2021 (39.9% versus 44.3%, p = 0.007). 70.2% experienced a worsening of at least one dimension of EuroQol-5D over last year, with patients in SWL being the most affected (p < 0.001). CONCLUSION: lockdown has caused in patients with musculoskeletal conditions a greater aggravation of pain and deterioration of quality of life than in the general population, especially in patients in SWL, translating in an increase in analgesics intake.

INTRODUCCIÓN: en Marzo de 2020 se estableció el confinamiento en España debido a la pandemia por COVID-19. El objetivo de este estudio es determinar su impacto en el dolor y la calidad de vida de personas con dolor osteomuscular. MATERIAL Y MÉTODOS: estudio prospectivo que incluyó 490 personas agrupadas en: 140 personas sin dolor (grupo 1), 140 personas con dolor osteomuscular, pero sin patología diagnosticada (grupo 2), 140 pacientes con patología musculoesquelética (grupo 3) y 70 pacientes en lista de espera quirúrgica (LEQ) por patología musculoesquelética (grupo 4). Se recogieron datos sobre el dolor, la actividad física y la calidad de vida (EuroQol-5D) al inicio del confinamiento y un año después. RESULTADOS: la edad media fue de 53 ± 17.5 años (18-88) y 51.3% fueron mujeres. Las personas en LEQ refirieron un dolor significativamente mayor que el resto de grupos (p < 0.001) con una puntuación en la escala visual analógica del dolor de 6.3 ± 1.9. Los grupos 3 y 4 sufrieron un aumento significativo de su dolor desde 2020 hasta 2021 (p < 0.001), mientras que en el grupo 2 disminuyó (p < 0.001). El consumo de analgésicos creció de 2020 a 2021 (39.9% versus 44.3%, p = 0.007); 70.2% sufrió un empeoramiento en alguna de las dimensiones del EuroQol-5D, siendo el grupo en LEQ el más afectado (p < 0.001). CONCLUSIONES: el confinamiento ha producido en pacientes con patología musculoesquelética un empeoramiento del dolor y de calidad de vida mayor que en el resto de personas, especialmente en aquéllas en espera de cirugía, traduciéndose en un aumento del consumo de analgésicos.

[Peripheral nerve stimulation in the treatment of various types of headache]. / Estimulación de nervio periférico en el tratamiento de diferentes tipo de cefaleas.

BACKGROUND AND OBJECTIVE: Headache has a great impact on patients' quality of life and in industrialized countries there is economic impact as well. One of the pathophysiologic theories to explain headache is activation of afferent C2-C3 nerve fibers. Afferent peripheral nerve stimulation by occipital nerve provocation at C2-C3 seems to alleviate headache by acting on the trigeminocervical complex, which would largely explain the effectiveness of this modality. The aim of this study was to describe peripheral nerve stimulation as an alternative therapy in patients who do not respond to other headache treatments. MATERIAL AND METHODS: Multicenter retrospective study between April 2005 and May 2009, analyzing cases of patients treated with nerve stimulation for severe chronic headache. In all patients the medical history included type of headache, intensity of pain on a numerical scale, medical treatment used, and number of headache episodes. We recorded the percentage of patients with negative tests. Patients implanted with a generator assessed effectiveness on the numerical scale; we analyzed the percentage of perceived improvement at 1, 3, 6, and 12 months. We also analyzed the extent of coverage provided by the electrodes, patient satisfaction, reduction in the number of episodes and medication, and complications. RESULTS: Of 31 patients, 87% had positive results, with a significant decrease in pain from baseline (P < .001); 85.2% reported sustained improvement of > 50%, and 96.3% reported a decrease of > 2 points on the pain scale. All patients expressed satisfaction during the period of follow-up. Fifty-six percent had no headaches after a year and 47% had stopped taking medication. The most frequent complication was electrode migration.

[Spinal granuloma in a patient receiving a spinal infusion of morphine and clonidine]. / Granuloma intradural en un paciente con infusión espinal de morfina y clonidina.

Patients treated with long-term spinal infusion of high doses of morphine develop a granuloma at the location of the catheter tip. Diagnosis is based on a steady increase in intrathecal morphine dosage after a relatively prolonged period of stability, on the gradual development of neurologic signs and symptoms suggesting radicular or spinal cord compression, and on magnetic resonance images. We describe a man with central neuropathic pain after removal of a tumor. The presence of all 3 of the aforementioned diagnostic criteria led to suspicion of a spinal granuloma.

[Effect of posture on spinal cord stimulation in patients with chronic pain syndromes: analysis of energy requirements in different patient postures]. / Efecto de la postura en la estimulación medular en pacientes con síndromes de dolor crónico. Análisis del gasto de energía dependiendo de la postura del paciente.

BACKGROUND AND OBJECTIVE: Patients being treated with spinal cord stimulation for chronic pain complain of variable paresthesias, particularly in relation to changes in posture. Such changes affect the great majority of patients with implantable pulse generators, requiring them to use the external programmer for avoidance of painful paresthesias or even to disconnect the generator, leading to loss of pain relief. The aim of this study was to determine the relationship between the pulse charge needed for stimulation and the patient's different postures. MATERIAL AND METHODS: Observational study of 70 patients treated with spinal cord stimulation in the following postures and situations: decubitus position, standing, seated, and walking. With the patients standing, we analyzed the thresholds of perception, pain, and pain relief, as well as the therapeutic range. Studies were performed in all patients. Later, data were analyzed by anatomical positioning of the stimulator (cervical, thoracic, sacral, occipital, or subcutaneous). RESULTS: In the analysis of the therapeutic range in the overall group we identified statistically significant differences between decubitus and standing positions and between decubitus position and walking. At the level of the thoracic spine differences were identified between all positions except between standing and walking and between seated and decubitus positions. At the level of the cervical spine, no significant differences were detected. Analysis of the pulse charge showed a significant difference in the decubitus position, in which less charge was needed to achieve satisfactory stimulation. When electrodes implanted at the cervical and thoracic levels were compared, differences were found between standing and seated positions (P=.04) but none between decubitus position or walking and the other positions. CONCLUSION: Stimulation systems are not currently designed to adapt to changes in distance between the electrodes and nerve fibers. Improvements are required in this respect.

Development of Surface-Coated Polylactic Acid/Polyhydroxyalkanoate (PLA/PHA) Nanocomposites.

This work reports on the design and development of nanocomposites based on a polymeric matrix containing biodegradable Polylactic Acid (PLA) and Polyhydroxyalkanoate (PHA) coated with either Graphite NanoPlatelets (GNP) or silver nanoparticles (AgNP). Nanocomposites were obtained by mechanical mixing under mild conditions and low load contents (<0.10 wt %). This favours physical adhesion of the additives onto the polymer surface, while the polymeric bulk matrix remains unaffected. Nanocomposite characterisation was performed via optical and focused ion beam microscopy, proving these nanocomposites are selectively modified only on the surface, leaving bulk polymer unaffected. Processability of these materials was proven by the fabrication of samples via injection moulding and mechanical characterisation. Nanocomposites showed enhanced Young modulus and yield strength, as well as better thermal properties when compared with the unmodified polymer. In the case of AgNP coated nanocomposites, the surface was found to be optically active, as observed in the increase of the resolution of Raman spectra, acquired at least 10 times, proving these nanocomposites are promising candidates as surface enhanced Raman spectroscopy (SERS) substrates.

[Use of rechargeable stimulators in 2 cases of cauda equina syndrome]. / Utilización de sistemas de estimulación recargables. A propósito de dos casos de síndrome de cola de caballo.

The first of the 2 cases of cauda equina syndrome we report occurred following phenolization of sacral roots after a series of operations for Hirsprung disease. The second occurred after trauma from a bullet that hit the spine. Fecal and urinary incontinence and neuropathic pain in the lower extremities were present in both cases. After various treatments failed, both patients were given dual spinal stimulation for integrated treatment of both incontinence and neuropathic pain. We applied a novel approach, connecting both stimulators to a single rechargeable generator, reducing medium- and long-term costs. Fewer generator replacements (every 2-3 years with the standard approach) and fewer generator implantations (2 each time with the usual system) are required when rechargeable generators are used. Patient quality of life is thus improved. The overall cost of the implants is reduced from their second year of use.

Impacto del confinamiento por la pandemia COVID-19 en el dolor musculoesquelético y la calidad de vida / Impact of COVID-19 pandemic confinement on musculoskeletal pain and quality of life

Resumen: Introducción: En Marzo de 2020 se estableció el confinamiento en España debido a la pandemia por COVID-19. El objetivo de este estudio es determinar su impacto en el dolor y la calidad de vida de personas con dolor osteomuscular. Material y métodos: Estudio prospectivo que incluyó 490 personas agrupadas en: 140 personas sin dolor (grupo 1), 140 personas con dolor osteomuscular, pero sin patología diagnosticada (grupo 2), 140 pacientes con patología musculoesquelética (grupo 3) y 70 pacientes en lista de espera quirúrgica (LEQ) por patología musculoesquelética (grupo 4). Se recogieron datos sobre el dolor, la actividad física y la calidad de vida (EuroQol-5D) al inicio del confinamiento y un año después. Resultados: La edad media fue de 53 ± 17.5 años (18-88) y 51.3% fueron mujeres. Las personas en LEQ refirieron un dolor significativamente mayor que el resto de grupos (p < 0.001) con una puntuación en la escala visual analógica del dolor de 6.3 ± 1.9. Los grupos 3 y 4 sufrieron un aumento significativo de su dolor desde 2020 hasta 2021 (p < 0.001), mientras que en el grupo 2 disminuyó (p < 0.001). El consumo de analgésicos creció de 2020 a 2021 (39.9% versus 44.3%, p = 0.007); 70.2% sufrió un empeoramiento en alguna de las dimensiones del EuroQol-5D, siendo el grupo en LEQ el más afectado (p < 0.001). Conclusiones: El confinamiento ha producido en pacientes con patología musculoesquelética un empeoramiento del dolor y de calidad de vida mayor que en el resto de personas, especialmente en aquéllas en espera de cirugía, traduciéndose en un aumento del consumo de analgésicos.

Abstract: Introduction: In March 2020, lockdown was established in Spain because of the COVID-19 pandemic. The aim of this study is to assess its impact on pain and quality of life in patients with musculoskeletal pain. Material and methods: Prospective study including 490 individuals grouped in: 140 people without pain, 140 people with musculoskeletal pain but without any related pathology diagnosed, 140 patients diagnosed for a musculoskeletal condition and 70 patients in surgical waiting list (SWL) for a musculoskeletal condition. Data regarding pain, physical activity and quality of life (EuroQol-5D) was collected at the beginning of lockdown and one year after (March 2021). Results: Mean age was 53 ± 17.5 years old (18-88) and 51.3% were women. Patients in SWL referred significantly more pain than the rest of groups (p < 0.001), with a score in the visual analogue scale of 6.3 ± 1.9. Groups 3 and 4 suffered a significant increase of their pain from 2020 to 2021 (p < 0.001), while decreasing in group 2 (p < 0.001). Analgesics intake grew from 2020 to 2021 (39.9% versus 44.3%, p = 0.007). 70.2% experienced a worsening of at least one dimension of EuroQol-5D over last year, with patients in SWL being the most affected (p < 0.001). Conclusion: Lockdown has caused in patients with musculoskeletal conditions a greater aggravation of pain and deterioration of quality of life than in the general population, especially in patients in SWL, translating in an increase in analgesics intake.

Recent advances on the use of cyclodextrins in the chiral analysis of drugs by capillary electrophoresis.

The most recent advances on the use of cyclodextrins as chiral selectors in capillary electrophoresis for the enantioseparation of drugs are reviewed in this article. The types of cyclodextrins employed and the resolutions achieved are discussed. The use of dual chiral systems, modified capillaries, non-aqueous media or microfluidic devices is also included and the mechanisms for enantioseparation of drugs and the inversion of the enantiomer migration order are studied. The most relevant applications developed to carry out the quantitation of chiral drugs, to assess the enantiomeric purity of pharmaceutical formulations, to study their metabolism or to achieve criminalistic or forensic investigations are described. Articles published in the last six years (period from 2010 to 2015) are considered.

Small-pore driven high capacitance in a hierarchical carbon via carbonization of Ni-MOF-74 at low temperatures.

A hierarchical porous carbon prepared via direct carbonization of Ni-MOF-74 loaded with furfuryl alcohol at 450 °C displays high specific capacitance in comparison with other MOF-derived carbons as a result of the formation of micropores smaller than 1 nm.

Epidemiological study of Rickettsia typhi infection in two provinces of the north of Spain: analysis of sera from the general population and sheep.

Data relating to Rickettsia typhi infection in Spain are scarce. A serological survey of 383 serum samples (184 males, 199 females) from the general population and 120 sera from sheep were studied by immunofluorescence assay (IFA). The human serum samples were collected from the general population of Palencia and Burgos provinces, and sheep serum samples were collected from Palencia province. Of the 383 human serum samples studied, 29 were positive for antibodies against R. typhi (7.5%) No statistical differences were found according to age, sex, origin (rural vs. urban) or geographic distribution, but a significant difference was observed related to occupation. In addition, 69 serums were found positives for R. typhi in sheep samples (57.5%). Our results indicated the circulation of R. typhi infectious for humans and sheep in Palencia and Burgos provinces. This study indicates that sheep may be infected with R. typhi, and that animals can, therefore be used as indicators of the presence of this organism.

Serological study of hantavirus in man in the Autonomous Community of Madrid, Spain.

Data relating to hantavirus infection in Spain are scarce and limited to rural areas. The aim of this work was to study the seroprevalence of hantavirus infection in the Autonomous Community of Madrid (ACM), a region containing both rural and urban populations in different ecological settings. Sera from 3852 individuals (1849 male, 2003 female) were screened by indirect inmunofluorescence, with Vero E6 cells infected with Puumala, Hantaan and Seoul viruses as antigens. Screen-positive results were confirmed by Western blot with recombinant Seoul virus nucleocapsid protein as antigen. Antibodies against hantavirus were detected in 12 sera (0.31%). No statistical differences were found according to sex and age. The highest prevalence was found in the southeastern area, significantly higher than the central and north-western areas. The most frequent serological pattern was reactivity against all three viruses used (33.3% of all positive sera). Therefore, this study confirms the presence of hantavirus infection in the ACM, including for the first time an urban area of Spain, but with the highest prevalence in a rural area. Serological evidence suggests that there is more than one circulating serotype.

Retention mechanism and implications for selectivity for a group of dihydropyridines in ionic micellar liquid chromatography.

The retention behaviour of a group of dihydropyridines in micellar liquid chromatography was studied using sodium dodecyl sulphate and hexadecyltrimethylammonium bromide as surfactants in the mobile phase containing 5% of n-butanol and a C18 column. When the surfactant concentration in the mobile phase is increased, a tendency to change from a three partition equilibria mechanism to direct transfer of solutes from micelles to the stationary phase is observed for both surfactants. This progressive change in the retention mechanism is explained through the large micellar phase-water partition coefficients of these compounds and the increase produced in the fraction of solute molecules in the micellar phase due to the increase in the volume of this phase originating from the increase in surfactant concentration. As a result, the selectivity coefficients show a tendency to match the ratio of the stationary phase to micellar phase partition coefficients of these compounds, constituting further proof of the progressive change in the retention mechanism when the surfactant concentration is increased.

Detection of bovine whey proteins by on-column derivatization capillary electrophoresis with laser-induced fluorescence monitoring.

1-Anilinonaphthalene-8-sulfonic acid (1,8-ANS), 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) and 2-(p-toluidino)naphthalene-6-sulfonic acid (2,6-TNS) were evaluated as additives in different buffers for the detection of bovine whey proteins using laser-induced fluorescence (LIF) monitoring in capillary electrophoresis (CE). These N-arylaminonaphthalene sulfonates furnish a large fluorescence emission when associated to some proteins whereas their emission in aqueous buffers, such as those used in CE separations, is very small. To select the best detection conditions, the fluorescence of these probes was first compared using experiments carried out in a fluorescence spectrophotometer. Using bovine serum albumin (BSA) as a model protein, it was demonstrated that 2-(N-cyclohexylamino)ethanesulfonic acid (CHES) buffer (pH 8 and pH 10.2) and the fluorescent probe 2,6-TNS gave rise to the highest increase in fluorescence for BSA. When the composition of these separation buffers was optimized for the electrophoretic separations, CHES buffer, pH 10.2 was chosen as the most suitable buffer to detect bovine whey proteins. The limit of detection obtained for some whey proteins in CE separations was about 6.10(-8) M for BSA, 3.10(-7) M for beta-lactoglobulin A (beta-LGA), 3.10(-7) M for beta-lactoglobulin B (beta-LGB), and 3.10(-6) M for alpha-lactalbumin (alpha-LA). These detection limits were compared to those achieved using UV detection under the same separation conditions. The results showed that the detection limits of BSA, beta-LGA and beta-LGB were twice as good using LIF than with UV detection. However, the limit of detection for alpha-LA was better when UV was used. The applicability of LIF detection to CE separation of whey proteins in bovine milk samples was also demonstrated.