Formación y seguridad en transporte pediátrico / Training and safety in pediatric transport

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Automatized sspKa measurements of dihydrogen phosphate and Tris(hydroxymethyl) aminomethane in acetonitrile/water mixtures from 20 to 60°C.

We measured pKa values of Tris(hydroxymethyl)aminomethane and dihydrogen phosphate; both are commonly used to prepare buffers for reverse-phase liquid chromatography (RPLC), in acetonitrile/water mixtures from 0% to 70% (v/v) (64.6% (w/w)) acetonitrile and at 20, 30, 40, 50, and 60°C. The procedure is based on potentiometric measurements of pH of buffer solutions of variable solvent compositions using a glass electrode and a novel automated system. The method consists in the controlled additions of small volumes of a thermostated solution from an automatic buret into another isothermal solution containing exactly the same buffer-component concentrations, but a different solvent composition. The continuous changes in the solvent composition induce changes in the potentials. Thus, only two sequences of additions are needed: increasing the amount of acetonitrile from pure water and decreasing the content of acetonitrile from 70% (v/v) (64.6% (w/w)). In the procedure with homemade apparatus, times for additions, stirring, homogenization, and data acquisition are entirely controlled by software programmed for this specific routine. This rapid, fully automated method was applied to acquire more than 40 potential data covering the whole composition range (at each temperature) in about two hours and allowed a systematic study of the effect of temperature and acetonitrile composition on acid-base equilibria of two widely used substances to control pH close to 7. The experimental pKa results were fitted to empirical functions between pKa and temperature and acetonitrile composition. These equations allowed predictions of pKa to estimate the pH of mixtures at any composition and temperature, which would be very useful, for instance, during chromatographic method development.

Polarographic behaviour of Aceclofenac, Tenoxicam and Droxicam in a methanol-water mixture.

A polarographic study about how three anti-inflammatories, such as Aceclofenac, Tenoxicam and Droxicam behave, using tast polarography (TP) and differential pulse polarography (DPP) was carried out. These studies were always carried out in a media formed by Methanol-Britton-Robinson aqueous buffer (0.1M) (4:96 (v/v)) due to the low solubility of these drugs in water. A strong influence of pH on analytical signals was observed, showing that the optimal pH values were between 4 and 5. Using DPP in the optimal experimental conditions, a detection limit of 10 ppb for Tenoxicam and Droxicam and 52 ppb for Aceclofenac was reached. The DPP proposed method was successfully applied to the determination of the active compounds in commercial drugs.

Polarographic study on the evolution of the diphenylamine as stabiliser of the solid propellants.

Differential pulse polarography (DPP) and square wave voltammetry (SWV) were investigated, in order to know the stability of solid propellants which contain diphenylamine. The simultaneous determination of N-nitrousdiphenylamine (NnDPA), 2-nitrodiphenylamine (2nDPA), 4-nitrodiphenylamine (4nDPA) and 2,4-dinitrodiphenylamine (2,4dnDPA) by DPP and SWV was proposed due to these nitro-derivatives appear during the stabilisation process from degradation of diphenylamine (DPA) used as stabiliser in propellant compositions. The proposed methods were successfully applied to the simple base solid propellant (with nitrocellulose as the only active component), with its stabiliser DPA. In all cases and with both the techniques, detection limits

Electrochemical behaviour of droxicam: kinetic study in aqueous-organic media.

A kinetic study of the hydrolytic decomposition of droxicam was carried out in order to establish the possible pharmacological action of the drug in the organism of the human being. The electrochemical technique used was scan cyclic voltammetry on a HMDE, giving a well-defined peak. Due to the insolubility of droxicam in water, the working media was a methanol-H(2)O (4:96, V/V) mixture. The decomposition product of droxicam is piroxicam, which is also reduced on a mercury electrode giving a well-defined cyclic voltammetric peak. It is proposed that the decomposition of droxicam is controlled by a kinetic equation: v=(1.93 x 10(-3)+78.9 [D]) [D]=k(D)[D].

Electrochemical study of antioxidants at a polypyrrole electrode modified by a nickel phthalocyanine complex. Application to their HPLC separation and to their FIA system detections.

A polypyrrole electrode modified with a tetrasulfonated nickel(II) phthalocyanine complex (GCE/PPy/NiPcTs) was used as amperometric electrochemical detector in a flow injection system, in order to determine some antioxidants in foods. The lather were separated by HPLC and detected at the modified electrode. Previous investigations carried out in our laboratory employed this electrode and cyclic voltammetry (CV), obtaining excellent results, due to an electrocatalytic effect on the oxidation of certain alimentary antioxidants, such tert-butylhydroquinone (TBHQ), 3-tert-butyl-4-hydroxyanisole (BHA) and propylgallate (PG). In order to obtain good separation, the chromatographic conditions were optimised. The geometry of the flow injection analysis (FIA) circuit and the reproducibility of the results were also optimised and, finally, the linear relationship between the signal and the concentration was verified. The proposed procedure is more precise and accurate than the conventional voltammetry methods. These results offer new analytical possibilities to this type of modified electrodes. The developed methods were applied to the determination of these antioxidants in commercial food.

Voltammetric determination of the phenolic antioxidants 3-tert-butyl-4-hydroxyanisole and tert-butylhydroquinone at a polypyrrole electrode modified with a nickel phthalocyanine complex.

The voltammetric behaviour of the antioxidants 3-tert-butyl-4-hydroxyanisole (BHA) and tert-butylhydroquinone (TBHQ), at a polymer electrode modified with nickel phthalocyanine as electron mediator, is described, and an electroanalytical method for the determination of these antioxidants based on their electrochemical oxidation on the modified electrode is proposed. Cyclic voltammograms showed well-defined oxidation peaks slightly shifted towards less positive potentials with respect to those obtained at the platinum disk electrode for both antioxidants. The peak currents measured at the modified electrode are considerably higher than those obtained at the unmodified electrode. A scan rate of 100 mV s(-1), a minimum methanol percentage of 0.5% and a 0.1-M Britton-Robinson medium were chosen as working conditions. The obtained results suggest that the BHA oxidation produces the TBHQ reduction product. This product is oxidised during the second cyclic scan, to generate the mentioned TBHQ as final product. These studies also reveal that sensitive response for both antioxidants can be obtained by using the differential pulse voltammetry (DPV) technique. Responses observed are dependent on the nature of the control solution (% methanol and pH) and the nature of voltammetric conditions (potential amplitude, DeltaE, and scan rate, v(b)). These factors have been modified in order to find the best analytical conditions. The mutual interferences between both antioxidants and the measurement reproducibility were tested. Using cyclic voltammetry (CV) and differential pulse voltammetry, BHA and TBHQ linear calibration graphs were obtained. The detection limits were 2.1 ppm for both when CV was used, and 18.7 ppm (BHA) and 1.23 ppm (TBHQ) for DPV. The developed methods were applied to the determination of BHA in spiked glaze biscuits and TBHQ in spiked mushroom cream.

Preparation of a polypyrrole electrode modified with a nickel phthalocyanine complex. Application to the determination of an antioxidant (propylgallate) in foods.

In this paper a study of the electrocatalytic oxidation of propylgallate (PG) by using a polypyrrole electrode modified with tetrasulfonate nickel (II) phthalocyanine complex (Pt/PPy/NiPcTs) was carried out. Several parameters of this polymeric electrode, such as: (a) its stability in hydroorganic solution, by using an indium tin oxide (ITO) electrode and spectrophotometry; and (b) its thickness using electrochemical techniques, have been studied. In addition, several parameters affecting the PG voltammetric peak, such as pH, methanol water ratio, potential scan rate and analyte concentration, were considered. Finally, the developed method was applied to the determination of PG in spiked potato flakes and cornflakes, showing its validity.

[Mycobacterium avium complex infection: a growing problem in our country]. / Infección por Mycobacterium avium cómplex: un problema creciente en nuestro entorno.

Since the emergence of AIDS, disseminated Mycobacterium avium complex (MAC) infection has become a growing cause of morbidity and mortality in this group of patients. Our objective was to study the incidence and the clinical and microbiological features of MAC infection in HIV-positive patients as well as the response to a therapy regimen combining clarithromycin and ethambutol. At our hospital, the first patient with disseminated MAC infection was diagnosed in 1988. Since then, 54 HIV-positive patients with MAC infection have been diagnosed (30/1,000 HIV-positive patients). MAC represented 12% of recovered mycobacteria in HIV-positive patients and this percentage has increased from 3.9% in 1988 to 16.4% in 1994. All episodes of MAC infection occurred in patients with advanced HIV diseases (mean CD4: 73/microliter). MAC infection was the disease diagnosing AIDS in 23.4% of cases. The most common clinical manifestations included fever (85.7%), weight loss (55%), and pulmonary involvement (50%). A total of 55 specimens were processed for mycobacterial culture from 54 patients (mean of 10.2 specimens per patient). A total of 122 were positive (21.9%: 2.25 positive specimens per patient). The specimens with the greater percentage of positive results were bone marrow aspirates (65.3%) and blood cultures (47.7%), followed by respiratory (16.5%) and urine specimens (5.3%). Regarding therapy, sixteen of the 54 investigated patients did not receive specific drugs for MAC infection, 7 were treated with different combinations of active drugs against MAC (rifampin, clofazimine, amikacin, ethambutol, and isoniazid) and 31 received a combination of clarythromicin (1 g/12 hourly) and ethambutol (400 mg/12 hourly). Seventy-four percent of patients treated with clarythromicin and ethambutol improved clinically, and the mean survival time in these patients (253 days) was significantly longer than that in not treated patients (p < 0.05). No significant differences were noted in survival time between the group of patients treated with clarythromicin and ethambutol and that with other drug combinations. The incidence of disseminated MAC infection in our environment is increasing in patients with advanced HIV disease. The combination of clarythromicin plus ethambutol was well tolerated and efficient for the treatment of disseminated MAC infection.

Fever of uncertain origin in patients infected with the human immunodeficiency virus.

To assess the frequency and etiology of fever of uncertain origin (FUO) in patients infected with the human immunodeficiency virus (HIV) and to evaluate the yield of diagnostic procedures used in their evaluation, we reviewed the clinical charts of all patients admitted to an AIDS unit during a 15-month period. FUO was defined by the endurance of a fever (temperature, > 38.2 degrees C) for at least 4 weeks before admission and the uncertainty of diagnosis after 3 days, despite appropriate investigation. Of 580 patients evaluated, 50 (8.2%) had FUO. Patients with FUO were at advanced stages of HIV infection (median CD4+ cell count, 71/mm3), and a vast majority (84%) had previously diagnosed AIDS. A cause of the fever was identified for 44 patients (88%), and infections accounted for 82% of all cases. Tuberculosis (42%), visceral leishmaniasis (14%), and disseminated Mycobacterium avium complex infection (14%) were the most frequent diagnoses. Examination of lymph node aspirates, bone marrow biopsy, and culture of clinical specimens for mycobacteria were the procedures with the highest diagnostic yield. Among 6 patients with fever of no identified etiology, 4 died while febrile, and fever was self-limited in the other 2 patients. FUO is common among patients with advanced HIV infection. Since a cause, usually infection, can be identified in most patients, long-lasting fever should not be attributed to HIV itself.

Determination of aceclofenac using adsorptive stripping voltammetric techniques on conventional and surfactant chemically modified carbon paste electrodes.

An electroanalytical method for determination of the anti-inflammatory agent aceclofenac at the ppb level using adsorptive stripping voltammetric techniques on conventional and surfactant chemically modified electrodes is developed. In this electroanalytical study a process of aceclofenac adsorption on carbon particles has been identified. In order to improve the aceclofenac determination, a chemical modification of the carbon paste was carried out employing several hydrophobic substances such as phospholipid and fatty acids, as well as several surfactants such as the non-ionic Triton X-100 and Triton X-405 and anionic sodium dodecyl sulfate. The influence of parameters such as pH, preconcentration time, carbon Nujol ratio, surfactant carbon ratio, potential scan rate, etc., on sensitivity of the method were widely studied. The proposed method was applied to the determination of the active compound in tablets.

Voltammetric determination of piroxicam in micellar media by using conventional and surfactant chemically modified carbon paste electrodes.

A method for piroxicam determination based on adsorptive stripping voltammetric techniques, using conventional and chemically modified carbon paste electrodes in micellar media, is described. The employed surfactants were sodium dodecyl sulfate (SDS), Triton X-100, Triton X-405, Tween 80 and Brij 30. However, the purpose of this paper is, at present, to research the use of surfactants as carbon paste modifier because one of the mechanisms of hydrophobic drugs ad-accumulation on the carbon paste electrode is based on the chemical affinity. Besides, because of the water piroxicam insolubility, a special aqueous medium, such as a surfactant solution above its c.m.c. was used, this micellar media being very advantageous in relation to the use of organic or aqueous-organic media, in order to dissolve the studied drug and to remove the problems derived from the organic solvents use. In addition, a piroxicam ad-accumulation increase, on surfactant modified carbon paste electrode, with the surfactant mass incorporated into the electrode, was observed.

Risk for developing tuberculosis among anergic patients infected with HIV.

OBJECTIVE: To assess the risk for development of tuberculosis among anergic patients infected with the human immunodeficiency virus (HIV). DESIGN: Retrospective cohort study. SETTING: Tertiary referral center. PATIENTS: All HIV-infected patients who had a baseline positive protein purified derivative test (PPD) and delayed-type hypersensitivity skin tests. MEASUREMENTS: Development of active tuberculosis. RESULTS: Of 374 patients, 108 (29%) had positive results of PPD tests, 154 (41%) had negative results of PPD tests but no skin anergy, and 112 (30%) were anergic. Conversion of the PPD to positive was observed in 10 of 67 (15%) patients with previously negative results of PPD tests and no anergy and in 3 of 36 (8%) anergic patients who were retested during the follow-up period (mean, 26 months). The risk for active tuberculosis to develop in patients not receiving isoniazid chemoprophylaxis was similar in patients with a positive PPD test result (10.4 cases per 100 person-years) and in anergic patients (12.4 cases per 100 person-years) and higher in both groups than in nonanergic patients with a negative PPD test result (5.4 cases per 100 person-years). Tuberculosis was more frequent among intravenous drug abusers with no previous isoniazid treatment (63 of 290, 22%) than among homosexual men (0 of 29) or patients in other HIV transmission categories (0 of 31). Preventive therapy with isoniazid reduced tuberculosis development (4% as compared with 31%; P = 0.008). Among 15 anergic patients who had CD4 counts measured within 3 months of tuberculosis development, only 1 (7%) had more than 500 CD4 cells/mm3. CONCLUSIONS: Anergic HIV-infected patients are at high risk for development of tuberculosis. Anergic HIV-infected patients, in addition to HIV-infected patients with positive results of PPD tests, should be offered preventive therapy if they live in areas with a high prevalence of tuberculosis, at least when the CD4 count decreases to less than 500 CD4 cells/mm3.

[A theoretical analysis of systemic arterial blood pressure of mammals (author's transl)]. / Análisis teórico de la presión sanguínea arterial sistémica de los mamíferos.

The theoretical reduced exponent b calculated for the arterial pressure, in accordance with Huxley's alometric equation, is 0; however the experimental value has shown different figures. In this paper it is proposed that systemic arterial pressure with exponent zero is in accordance with that of those arteries found at a greater distance of the heart but above cardiac level. We postulate that the cerebral arteries have an experimental exponent b = 0. We have calculated this exponent for the cephalic arterial pressure (arterial pressure at cardiac level minus hydrostatic pressure for cephalic level). With this correction, we have found a better correlation between experimental and theoretical figures in accordance with the theory of biological similarities.