Determination of Chlordiazepoxide by Zinc or Cadmium Reduction in a Continuous System Followed by Atomic Absorption Spectrometric Detect ion

The analytical possibilities of using simple unsegmented configurations including redox columns for the selective determination of organic compounds with atomic absorption spectrometric detection are discussed. A method based on reduction with cadmium or zinc was developed for the determination of chlordiazepoxide in pharmaceutical preparations. This drug can be determined in the range 2.0-25 pg ml-1 with a relative standard deviation between 1.1 and 2.8% and a sampling frequency of 150 h-1. The method is selective towards the reduction of the N-oxide group and permits the determination of chlordiazepoxide in the presence of other 1,4-benzodiazepines. Keywords: Atomic absorption spectrometry; flow injection; chlordiazepoxide determination; metal reducing column Chlordiazepoxide is a major sedative -hypnotic drug widely employed as a tranquilliser and antidepressant. Like other 1,6benzodiazepines, it has been extensively studied.1.2 Several techniques, including spectrophotometry,3 spectrofluorimetry,4 polarography,s.6 thin-layer chromatography,7 high-performance liquid chromatography (HPLC) ,8,9 gas chromatography (GC) 10 and plasma chromatography11 have been reported for its determination. The US Yharmacopeial2 and the European Pharmacopoeia13 propose a spectrophotometric method based on the acid hydrolysis of the drug to its corresponding aminobenzophenone , followed by formation of a violet complex by diazotisation and coupling with N-lnaphthylethylenediamine. In addition, G C analysis is further complicated by the thermal instability of some of these compounds, particularly chlordiazepoxide, and HPLC analysis often requires a carefully selected mobile phase and is very expensive. The high selectivity and sensitivity offered by atomic absorption spectrometry (AAS) has been exploited for the indirect determination of various organic pharmaceutical compounds by manual procedures. 14915 The only AAS method for the determination of two benzodiazepines (bromazepam and flurazepam) reported so far is based on the extraction of these drugs as ion pairs into isobutyl methyl ketone. There has been increasing interest in automated methods of analysis in recent years.16-18 Different types of solid reactors have been employed in conjunction with unsegmented-flow configurations as ion-exchange columns, enzyme reactors and redox reactors. The last type have been used for the speciation of nitrite and nitrate by the modified Griess reaction using cadmium and copper-coated cadmium c0lumns.19~2~) The analytical applications of unstable oxidising and reducing agents in aqueous solutions in flow analysis were recently reviewed by den Boef.21 This paper reports an indirect method using flame AAS detection for the determination of chlordiazepoxide (Librium) in pharmaceutical preparations. It is based on the selective reduction of the N-oxide group by using reducing columns coupled on-line to a flow injection system. A detailed study of the different analytical possibilities of various reducing columns (some of which were originally designed for this work), which can be located either inside or outside the loop of the valve, was made. Other benzodiazepines are not reduced by these systems. Experimental Instruments and Apparatus A Perkin-Elmer 380 atomic absorption spectrometer equipped with suitable hollow-cathode lamps (zinc or cadmium) and an adjustable nebuliser was used. The instrument was operated with deuterium-arc background correction and the air -acetylene flame was adjusted according to the recommendations of the manufacturer. The spectrometer output was connected to a Radiometer REC-80 Servograph recorder. The peristaltic pump was a Gilson Minipuls-2, furnished with poly(viny1 chloride) pump tubing. The injector consisted of a rotary valve (Tecator Model L 100-1) to which a loop of the required volume was fitted; PTFE tubing (0.5 mm i d . ) and a selection valve (Rheodyne Model 5041) were also used. Different laboratory-made columns were employed for reduction purposes. Reagents The benzodiazepines were obtained from Sigma and Roche in both pure and tablet forms. The ethanol solutions of the drugs were protected from light during the analyses. A stock solution of chlordiazepoxide hydrochloride (1 .OOO g 1-1) was prepared in absolute ethanol and was stable for several weeks. Less concentrated solutions were obtained by dilution of this stock solution with distilled water. Redox Columns The reduction columns were made by packing a glass capillary (4.5 or 8.5 cm X 1.8 mm i.d.) with cadmium or zinc granules (Merck) of medium size (grain diameter 0.5-1.2 mm). Copper-coated cadmium columns (4.5 or 8.5 cm long) were prepared in a similar manner with cadmium granules that had been previously coated with copper by passing a 0.1% copper(I1) sulphate -0.1 M ethylenediaminetetraacetic acid solution over them. Amalgamated zinc columns were prepared by packing the capillary (4.5 cm or 8.5 cm long) with zinc granules and then passing 2% nitric acid -0.25 M mercury nitrate solution through it

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

El desarrollo del currículo de Historia en Bachillerato y el uso de los textos: la visión del profesorado

En materias corno la Historia, la interpretación del currículum establecido en los decretos legislativos por parte del docente, condiciona a su vez el modo en que los alumnos acceden a un conocimiento de la realidad social, de ahí que sea más interesante llegar a saber cómo se preparan y realizan las clases de Historia por parte de los profesores, cuál es la metodología que utilizan y en qué basan sus decisiones cuando diseñan la asignatura. Sin duda, uno de los grandes condicionantes a la hora de dar respuesta a estos interrogantes suele ser el material elegido para facilitar el aprendizaje de los alumnos, material que en la mayoría de los casos suele seguir reduciéndose a la utilización de un manual o libro de texto, sin que se sepa muy bien cuáles son las razones que han impulsado esta elección. A partir de los datos recogidos hasta el momento parece que en muchos casos los textos vienen dados por motivos ajenos a criterios científicos o pedagógicos tales, corno son la necesidad de mantener los libros una serie de años en el centro escolar, o las ofertas más o menos comerciales de las distintas editoriales, pero quizás necesitemos profundizar más en este campo a fin de confinnar o matizar estas hipótesis, de ahí nuestro interés por estudiar y analizar estos aspectos.Peer reviewe

New opportunities for developing tomato varieties with enhanced carotenoid content

ABSTRACT The development of varieties with a high content of antioxidant compounds, such as carotenoids, has become a major focus in the marketing of tomato. Several mutants have been used in the development of high pigment varieties, but the significant influence of the environment on carotenoid content and the presence of negative side effects in vegetative growth and yield have limited the success of these variants. Consequently, the identification of alternative sources of variation in the quest for high carotenoid content is ongoing. In this study, 12 accessions of Solanum lycopersicum (including the former var cerasiforme) and S. pimpinelifolium have been evaluated in three different environments: open field and glasshouse cultivation at two sites. Three accessions (BGV6195 of S. pimpinellifolium, LA1423 of the former var cerasiforme and LA3633 a possible hybrid between S. pimpinellifolium and S. lycopersicum) showed outstanding and stable lycopene content, that doubled in all three environments the content of the positive control LA3538, with the high pigment-1 mutation (hp1). In addition, accession CATIE14812 would also be interesting as regards improvement of β-carotene content. These materials offer new opportunities in the development of tomato varieties with enriched and reliable carotenoid content and the close taxonomic relationship of these accessions with cultivated tomato will facilitate their use in breeding programs

Recognition of foot-and-mouth disease virus and its capsid protein VP1 by bovine peripheral T lymphocytes

The role of T cells in immunity to foot-and-mouth disease virus is still poorly defined compared to that of the humoral response. In this paper we describe a systematic, longitudinal study on the cellular recognition of FMDV and its subunit protein VP1 by bovine peripheral blood T lymphocytes. Multiple vaccination with a single virus serotype induced a serotype cross-reactive proliferative T cell repertoire that varied in magnitude between individual animals and with the serotype of the vaccine used. Primary proliferative T cell responses of vaccinated and acutely infected cattle were weak relative to the magnitude of responses determined for the same animals after boosting. In contrast, the level of circulating antibody produced after both primary and secondary exposure to virus was good. Phenotypic analysis of lymphocytes from vaccinated or infected cattle showed a small increase in CD8+ T cells after infection compared to vaccination. However, in general the profiles of circulating lymphocytes elicited were similar. Thus, we were not able to use proliferative or phenotypic analyses to distinguish between vaccinated and convalescent cattle. T cell recognition of VP1 by multiply-vaccinated cattle was serotype-specific implying that the cross-reactive responses observed with whole virus may be attributed to proteins other than VP1. In contrast to other studies, immunization with recombinant VP1 induced only low levels of neutralizing antibody and failed to elicit profound proliferative responses or protection even after two immunizations.</p

New opportunities for developing tomato varieties with enhanced carotenoid content

ABSTRACT The development of varieties with a high content of antioxidant compounds, such as carotenoids, has become a major focus in the marketing of tomato. Several mutants have been used in the development of high pigment varieties, but the significant influence of the environment on carotenoid content and the presence of negative side effects in vegetative growth and yield have limited the success of these variants. Consequently, the identification of alternative sources of variation in the quest for high carotenoid content is ongoing. In this study, 12 accessions of Solanum lycopersicum (including the former var cerasiforme) and S. pimpinelifolium have been evaluated in three different environments: open field and glasshouse cultivation at two sites. Three accessions (BGV6195 of S. pimpinellifolium, LA1423 of the former var cerasiforme and LA3633 a possible hybrid between S. pimpinellifolium and S. lycopersicum) showed outstanding and stable lycopene content, that doubled in all three environments the content of the positive control LA3538, with the high pigment-1 mutation (hp1). In addition, accession CATIE14812 would also be interesting as regards improvement of β-carotene content. These materials offer new opportunities in the development of tomato varieties with enriched and reliable carotenoid content and the close taxonomic relationship of these accessions with cultivated tomato will facilitate their use in breeding programs