Structure and dynamics of a 1,4-polybutadiene melt in an alumina nanopore: A molecular dynamics simulation.

We present results of molecular dynamics simulations of a chemically realistic model of 1,4-polybutadiene confined in a cylindrical alumina nanopore of diameter 10 nm. The simulations are done at three different temperatures above the glass transition temperature Tg. We investigate the density layering across the nanopore as well as the orientational ordering in the polymer melt, brought about by the confinement, on both the segmental and chain scales. For the chain scale ordering, the magnitude and orientation of the axes of the gyration tensor ellipsoid of single chains are studied and are found to prefer to align parallel to the pore axis. Even though double bonds near the wall are preferentially oriented along the pore walls, studying the nematic order parameter indicates that there is no nematic ordering at the melt-wall interface. As for the dynamics in the melt, we focus here on the mean-square-displacement of the monomers for several layers across the nanopore as well as the movement of the chain center of mass both of which display a slowing down of the dynamics in the layer at the wall. We also show the strong adsorption of the monomers to the pore wall at lower temperatures.

Role of torsional potential in chain conformation, thermodynamics, and glass formation of simulated polybutadiene melts.

For polymer chains, the torsional potential is an important intramolecular energy influencing chain flexibility and segmental dynamics. Through molecular dynamics simulations of an atomistic model for melts of cis-trans-1,4-polybutadiene (PBD), we explore the effect of the torsions on conformational properties (bond vector correlations and mean-square internal distances), fundamental thermodynamic quantities (density, compressibility, internal energy, and specific heat), and glass transition temperature Tg. This is achieved by systematically reducing the strength of the torsional potential, starting from the chemically realistic chain (CRC) model with the full potential toward the freely rotating chain (FRC) model without the torsional potential. For the equilibrium liquid, we find that the effect of the torsions on polymer conformations is very weak. Still weaker is the influence on the monomer density ρ and isothermal compressibility κT of the polymer liquid, both of which can be considered as independent of the torsional potential. We show that a van der Waals-like model proposed by Long and Lequeux [Eur. Phys. J. E 4, 371 (2001)] allows us to describe very well the temperature (T) dependence of ρ and κT. We also find that our data obey the linear relation between 1/kBTρκT and 1/T (with the Boltzmann constant kB) that has recently been predicted and verified on the experiment by Mirigian and Schweizer [J. Chem. Phys. 140, 194507 (2014)]. For the equilibrium liquid, simulations result in a specific heat, at constant pressure and at constant volume, which increases on cooling. This T dependence is opposite to the one found experimentally for many polymer liquids, including PBD. We suggest that this difference between simulation and experiment may be attributed to quantum effects due to hydrogen atoms and backbone vibrations, which, by construction, are not included in the classical united-atom model employed here. Finally, we also determine Tg from the density-temperature curve monitored in a finite-rate cooling process. While the influence of the torsional potential on ρ(T) is vanishingly small in the equilibrium liquid, the effect of the torsions on Tg is large. We find that Tg decreases by about 150 K when going from the CRC to the FRC model.

Clinical predictors of complications in patients with left-sided infective endocarditis: A retrospective study of 206 episodes.

PURPOSE: Early identification of specific patient subgroups at high risk of developing life-threatening infective endocarditis (IE) complications is of paramount importance. Better stratification may allow more intensive treatment of these patients and positively influences clinical outcomes. METHODS: We carried out a retrospective survey of consecutive left-sided IE adult patients, admitted over a 15-year period to two main tertiary care centres in the Czech Republic. RESULTS: Among a group of 196 patients (155 males; median age 64 years), a total of 206 left-sided IE episodes were identified. Perivalvular extension of infection was most frequently seen in prosthetic aortic valve endocarditis (OR 6.706, p<0.0001). Valve prolapse/perforation during IE episodes was significantly associated with mitral valve IE (OR 2.136, p=0.026) and vegetation length (OR 1.055, p=0.009). Septic shock was significantly related to two main risk factors: S. aureus infection (OR 8.459, p=<0.0001) and smoking (OR 8.403, p=0.001). Mitral valve IE with a vegetation length ≥13 mm was the strongest risk factor for this complication (OR 3.24, p=0.001), followed by S. aureus infection (OR 3.59, p=0.002). Finally, septic shock (OR 6.000, p=0.001) represented the most important risk factor of in-hospital mortality. CONCLUSIONS: This study provides the most detailed profile of complication predictors related to left-sided IE in Central Europe. Early individual stratification of IE related occurrence of complications might help to decrease extremely high morbidity and mortality of this disease (Tab. 5, Ref. 37).

Relaxation processes and glass transition of confined polymer melts: A molecular dynamics simulation of 1,4-polybutadiene between graphite walls.

Molecular dynamics simulations of a chemically realistic model for 1,4-polybutadiene in a thin film geometry confined by two graphite walls are presented. Previous work on melts in the bulk has shown that the model faithfully reproduces static and dynamic properties of the real material over a wide temperature range. The present work studies how these properties change due to nano-confinement. The focus is on orientational correlations observable in nuclear magnetic resonance experiments and on the local intermediate incoherent neutron scattering function, Fs(qz, z, t), for distances z from the graphite walls in the range of a few nanometers. Temperatures from about 2Tg down to about 1.15Tg, where Tg is the glass transition temperature in the bulk, are studied. It is shown that weakly attractive forces between the wall atoms and the monomers suffice to effectively bind a polymer coil that is near the wall. For a wide regime of temperatures, the Arrhenius-like adsorption/desorption kinetics of the monomers is the slowest process, while very close to Tg the Vogel-Fulcher-Tammann-like α-relaxation takes over. The α-process is modified only for z≤1.2 nm due to the density changes near the walls, less than expected from studies of coarse-grained (bead-spring-type) models. The weakness of the surface effects on the glass transition in this case is attributed to the interplay of density changes near the wall with the torsional potential. A brief discussion of pertinent experiments is given.

Dielectric α-relaxation of 1,4-polybutadiene confined between graphite walls : Molecular dynamics investigations through numerical simulations of polymer molecules relaxation.

We present results of Molecular Dynamics (MD) simulations of a chemically realistic model of 1,4-polybutadiene confined by crystalline graphite walls. The simulations cover a large range of temperatures from T ≈ 2T g to T ≈ 1.15T g, where relevant time scales are accessible using such computational methods. We investigate the dielectric relaxation close to the walls in comparison to the one in the center of the film, and study the latter as a function of the film thickness from the walls. The segmental dynamics in the film is slowed down close to the walls, in comparison to the bulk. In addition to the α-process, the relaxation exhibits an additional long time decay, the so-called wall desorption process. We focus here on the α-process and find no significant shift of the dielectric T g as a function of layer thickness, in agreement with recent dielectric experiments. These findings can be correlated with the importance of the dihedral dynamics for all relaxation processes in polymers, which is unaltered except for the first nanometer next to the walls.

The role of urinary aldosterone for the diagnosis of primary aldosteronism.

When diagnosing primary aldosteronism, the measurement of urinary aldosterone after oral sodium loading is one of the currently recommended confirmatory tests. The aim of the study was to assess the repeatability and interpretation of urinary aldosterone in patients examined for suspected primary aldosteronism. Sixty-four hypertensive patients with suspected primary aldosteronism were prospectively enrolled and examined according to the study protocol. After antihypertensive medications interfering with renin-angiotensin-aldosterone system were withdrawn for at least 2 weeks, the confirmatory testing was performed: oral sodium loading preceded the collection of 24-h urine sample and subsequent saline infusion test. The identical procedures were repeated after 2 weeks. The concordant results of both saline infusion tests served for confirmation/exclusion of primary aldosteronism. Forty-nine patients were included in data analysis. Primary aldosteronism was excluded in 16, and confirmed in 33 individuals. The repeatability of urinary aldosterone was evaluated in 44 patients: the difference of urinary aldosterone levels ranged between 1 and 88% (median 31%). Ninety-three urine samples from 49 patients were used to validate the interpretation of urinary aldosterone in respect to the diagnosis of primary aldosteronism made by saline infusion testing; 96% sensitivity was characterized by urinary aldosterone ≥19 nmol/day, and 96% specificity was associated with urinary aldosterone ≥92 nmol/day. In 22 (45%) patients, urinary aldosterone remained in the "gray" zone between 19 and 92 nmol/day in all provided samples. The estimation of urinary aldosterone excretion after oral sodium loading is associated with marked intraindividual variability, and significant number of inconclusive results.

Analysis of local properties during a scratch test on a polymeric surface using molecular dynamics simulations.

This work demonstrates a possible route to connect a particle (chain) based understanding with continuum mechanical questions about contact mechanics. The bond orientation, chain conformation and stress field of a polymer film were analyzed during scratch tests (tangential contact) using a molecular dynamics (MD) simulation approach. Scratch tests with a conical tip at constant scratching velocity were simulated on linear amorphous polymer surfaces at various temperatures and roughnesses of the tip and for various interactions between the tip and the particles of the polymer chains. The second Legendre polynomial (computed for small domains around the tip) gave the bond orientation inside the polymer film during sliding of the tip. The gyration tensor (layer-resolved in the direction of the polymer film thickness) provided information about the conformation of the polymer chains. These results allowed us to argue in favor of Briscoe's hypothesis (thin film sheared vs. "bulk" compressive behavior) concerning the friction properties of the polymer surfaces. Finally, the first stress measurements of the virial stress tensor (in sub-boxes placed in the MD cell) revealed a complex combination between compressive hydrostatic pressure and shear stress, which may be interpreted as a complex sheared domain at the interface.

Neurovascular compression: sympathetic activity in severe arterial hypertension.

Compression of the rostral ventrolateral medulla oblongata (RVLM) by an abnormally located artery is regarded as one possible cause of arterial hypertension. There exists a limited set of data suggesting that increased sympathetic activity in patients with RVLM compression may lead to arterial hypertension. Accordingly, we decided to assess the sympathetic activity in patients with severe arterial hypertension and to investigate any correlation with the presence of RVLM compression. Sixty-four patients with severe arterial hypertension were enrolled in our study. Sympathetic activity was evaluated using 24-hour urinary norepinephrine as measured by high-pressure liquid chromatography with electrochemical detection. The presence of RVLM compression was assessed with magnetic resonance imaging. Neurovascular compression of the RVLM was identified in 40 patients, 27 of whom presented left-sided compression. Twenty-four hour urinary norepinephrine averaged 263.6+/-135.9 nmol in patients with neurovascular compression - 255.6+/-137.3 nmol in those with left-sided compression and 251.6+/-138.5 nmol in patients without RVLM compression. We did not identify any increase in urinary norepinephrine in patients with severe arterial hypertension and neurovascular compression of the RVLM. Our results do not support the hypothesis that neurovascular compression of RVLM may exhibit a sympathetically mediated increase in blood pressure.

[Is confirmation of an adrenal adenoma in patients with primary aldosteronism sufficient for indication of adrenalectomy?]. / Je prukaz adenomu nadledviny u pacientu s primárním hyperaldosteronizmem dostatecný pro indikati adrenalektomie?

BACKGROUND: Primary aldosteronism is one of the most common forms of secondary arterial hypertension. Adrenalectomy is effective in patients with proven unilateral hypersecretion of aldosterone whereas pharmacotherapy is indicated in bilateral forms of the disease. We can meet the opinion that in patients with confirmed primary aldosteronism and finding ofsuprarenal adenoma > or = 1 cm on computed tomography (CT) scanning, adrenalectomy can be recommended without further investigation. On the other hand we can perform adrenal venous sampling (AVS) to prove unilateral overproduction of aldosterone. OBJECTIVES: To evaluate whether AVS is necessary in all patients with unilateral adenoma > or = 1 cm. METHODS: We analyzed data from patients with proven primary aldosteronism, CT finding of adenoma > or = 1 cm along with normal morphology of contralateral adrenal gland, and successfully performed AVS. RESULTS: Out of 107 patients with proven primary aldosteronism, indicated for AVS, we included 30 patients with CT finding of suprarenal adenoma > or = 1 cm along with normal morphology of contralateral adrenal gland and successful AVS. Unilateral overproduction of aldosterone was found only in 17 cases (56.7%), the results in remaining 13 patients (43.3%) did not confirm activity of adenoma. CONCLUSION: Our results support necessity of performing AVS in all patients with primary aldosteronism in whom surgical treatment is considered, CT confirmation ofan adenoma is insufficient in this indication.

[Current use of magnetic resonance imaging in cardiology]. / Soucasné moznosti zobrazení magnetickou rezonancí v kardiologii.

Magnetic resonance imaging is a modern imaging technique that is characterized by high resolution and variable tomographic slices. The development of magnetic resonance technology in last decade led to the expansion of this method in many fields of medicine. In cardiology, the imaging is focused on the heart, aorta, pulmonary, coronary and renal arteries. Dynamic imaging is used for the evaluation of the kinetics and the function of the ventricles. Static imaging serves for the assessment of the myocardial wall in patients with cardiomyopathies and coronary artery disease. The quality of static imaging can improve paramagnetic contrast agent that increasingly accumulates in areas of acute necrosis, fibrosis or infiltration of the myocardium. Magnetic resonance imaging can also diagnose intracardiac tumors and thrombi, valvular heart disease and pericardial disorders. Despite of wide spectrum of diagnostic applications, the clinical use of magnetic resonance imaging is reduced by limited availability and high cost of the examination.

Hyperglycaemic hyperosmolar nonketotic state as a cause of low gonadotrophin levels in postmenopausal diabetic women: a role for severe hypernatraemia.

Hypogonadotrophic hypogonadism is associated with uncontrolled diabetes mellitus. Hyperglycaemia is a unique metabolic abnormality of the hyperglycaemic hyperosmolar nonketotic state (HHNKS) and, as glucose availability regulates gonadotrophin release, we investigated whether gonadotrophin release is inhibited in diabetic women with HHNKS, and whether hyperglycaemia, hypernatraemia or both inhibit in vitro gonadotrophin-releasing hormone (GnRH) expression in GT1-7 neurones. Three groups of postmenopausal women were studied: nine diabetics with HHNKS, nine hospitalised ill nondiabetics and 15 healthy women. In addition, the effects of glucose (5.55, 33.3, 66.6 mmol/l) and sodium chloride (150 and 170 mmol/l) on GnRH expression were investigated using GT1-7 neurones. Postmenopausal diabetics with HHNKS showed a decrease in serum levels of luteinising hormone (diabetic HHNKS 2.2 +/- 0.9 IU/l versus ill nondiabetic 21.0 +/- 2.3 IU/l and healthy controls 20.9 +/- 2.8 IU/l, P < 0.01), follicle-stimulating hormone (diabetic HHNKS 8.2 +/- 2.1 IU/l versus ill nondiabetic 50.4 +/- 9.1 IU/l and controls 60.2 +/- 6.9 IU/l, P < 0.01) and free 3,5,3'-triiodothyronine (diabetic HHNKS 1.48 +/- 0.57 pmol/l versus ill nondiabetic 4.28 +/- 0.26 pmol/l and controls 3.88 +/- 0.11 pmol/l, P < 0.01). The plasma cortisol level was higher in both diabetic (985 +/- 130 nmol/l) and ill nondiabetic (726 +/- 52 nmol/l) women than in healthy women (512 +/- 47 nmol/l), but no differences were observed in plasma oestradiol, thyroid-stimulating hormone or free thyroxine. In vitro GT1-7 neurones expressed three-fold less GnRH at 170 mmol/l than at 150 mmol/l NaCl, whereas changing glucose concentrations in the culture medium did not affect GnRH expression. In conclusion, postmenopausal diabetic women with HHNKS show decreased serum gonadotrophin levels, and severe hypernatraemia may participate in the hypogonadotropism observed in HHNKS.

Thermal analysis in the evaluation of sediment pollution.

Characterization of organic matter in four sediments in the infuence area of wastewater discharges was carried out by both chemical and thermal analysis in order to assess their pollution level. Oxidisable organic carbon and organic matter were calculated by the standard methodology in laboratory. Thermogravimetry (TG), between 50 and 900 degrees C, was simultaneously performed in oxidizing conditions on ground sediments samples after three different pretreatments. Linear regression adjust of thermal analysis results versus chemical parameters provides the better Pearson's coefficients, leading to the best coefficients for weight loss in 250-400 degree C temperature range versus oxidisable organic carbon and organic matter at 360 degrees C, respectively. These results demonstrated the utility of thermoanalysis technique for the evaluation of the organic matter content of fresh sediments.

Disinfection of dairy and animal farm wastewater with radiofrequency power.

Radiofrequency (RF) power was investigated as a new, physical (nonchemical), thermal process to disinfect wastewater from dairy and animal facilities. Samples (n = 38) from 8 dairy, 2 calf, and 3 swine facilities in California were collected over a 3-yr period and characterized for their dielectric properties, chemical composition, and suitability for thermal processing using RF power. To establish efficacy for disinfection, selected samples were inoculated with high levels (10(6) to 10(9) cfu/mL) of bacterial pathogens such as Salmonella sp., Escherichia coli O157:H7, and Mycobacterium avium ssp. paratuberculosis and processed with an RF prototype system. The capabilities of RF power as a method for thermal disinfection of wastewater were demonstrated when bacteria pathogens were completely and rapidly (<1 min) inactivated when temperatures of 60 to 65 degrees C were achieved. Furthermore, RF technology can be used for large-scale, batch or continuous and portable applications, allowing significant improvements in energy-use efficiencies compared with conventional thermal (surface heating) technologies. Therefore, RF power has potential as an alternative to disinfect dairy/animal farm wastewater before recycling.

A randomized, double-blind, placebo-controlled study of verapamil and metoprolol in treatment of multifocal atrial tachycardia.

PURPOSE: Multifocal atrial tachycardia is a difficult arrhythmia to treat. Patients not showing a response to the correction of predisposing conditions present a therapeutic dilemma. To assess the efficacy of two agents reported to be effective in this condition, verapamil, metoprolol, or placebo was given intravenously in a randomized, double-blind trial. PATIENTS AND METHODS: Thirteen patients meeting inclusionary criteria were enrolled. Therapeutic response was defined as conversion to sinus rhythm, a decline in the ventricular rate of 15 percent or more [corrected], or a ventricular rate of less than 100 beats/minute. Four male and nine female patients having a mean age (+/- SD) of 81.9 +/- 14.2 years were enrolled. Automated serum chemistries, complete blood cell count with differential, arterial blood gas values, and serum digoxin and theophylline levels were determined and a 12-lead electrocardiogram was obtained at the start of the trial. Following the completion of each phase of the study, a repeat physical examination was performed, and arterial blood gas values and an electrocardiogram were obtained. The trial was designed to run for two days. RESULTS: Two of 10 (20 percent), four of nine (44 percent), and eight of nine (89 percent) showed a response to placebo, verapamil, or metoprolol, respectively. Mean slowing of ventricular rate was 3.4, 7.3, and 24.5 percent for placebo, verapamil, and metoprolol, respectively (p less than 0.01 for metoprolol versus placebo). Five patients who showed a response to metoprolol had failed to have a response to verapamil. CONCLUSION: We conclude that metoprolol appears to be more effective than verapamil in treating multifocal atrial tachycardia. However, careful patient selection is necessary in its use.

Renal clearance and extraction parameters of ortho-iodohippurate (I-123) compared with OIH(I-131) and PAH.

o-[131I] iodohippurate [OIH(I-131)] has been used for many years in the estimation of effective renal plasma flow. This compound suffers from low photon yield and poor images when the quantity used is limited to stay within a reasonable radiation dose. To test the validity of substituting I-123 for I-131, a series of experiments was performed in a surgically prepared dog model. The extraction ratios and clearance values OIH(I-123) prepared from radionuclidically pure I-123 were compared with those of commercial OIH(I-131) and PAH. The extraction ratios for OIH(I-123) and OIH(I-131) were 0.65 and 0.67, representing 0.86 and 0.88 that of PAH, respectively. The clearance values (cc/min/kg) for the I123 and I-123) can be used to estimate effective renal plasma flow; moreover, because of the high yield within an acceptable radiation dose range, images of good quality can be produced.

Iodine-123 metaiodobenzylguanidine imaging of the heart in idiopathic congestive cardiomyopathy and cardiac transplants.

Iodine-123 metaiodobenzylguanidine ([123I]MIBG) is a norepinephrine analog which can be used to image the sympathetic innervation of the heart. In this study, cardiac imaging with [123I]MIBG was performed in patients with idiopathic congestive cardiomyopathy and compared to normal controls. Initial uptake, half-time of tracer within the heart, and heart to lung ratios were all significantly reduced in patients compared to normals. Uptake in lungs, liver, salivary glands, and spleen was similar in controls and patients with cardiomyopathy indicating that decreased MIBG uptake was not a generalized abnormality in these patients. Iodine-123 MIBG imaging was also performed in cardiac transplant patients to determine cardiac nonneuronal uptake. Uptake in transplants was less than 10% of normals in the first 2 hr and nearly undetectable after 16 hr. The decreased uptake of MIBG suggests cardiac sympathetic nerve dysfunction while the rapid washout of MIBG from the heart suggests increased cardiac sympathetic nerve activity in idiopathic congestive cardiomyopathy.

Treatment of severe left ventricular dysfunction with calcium chloride in patients receiving verapamil.

This report describes two patients who received verapamil because of supraventricular arrhythmias. The patients both developed severe hypotension and signs of left ventricular compromise. The hypotension and left ventricular compromise were promptly reversed by administration of intravenous calcium chloride. The dramatic improvement was documented clinically and in one case by two-dimensional echocardiography.

Positron emission tomography assessment of effects of benzodiazepines on regional glucose metabolic rate in patients with anxiety disorder.

Patients with generalized anxiety disorder (n = 18) entered a 21-day, double-blind, placebo-controlled random assignment trial of clorazepate. Positron emission tomography with 18F-deoxyglucose was carried out before and after treatment. Decreases in glucose metabolic rate in visual cortex and relative increases in the basal ganglia and thalamus were found. A correlation between regional changes in metabolic rate and regional benzodiazepine receptor binding density from other human autopsy studies was observed; brain regions highest in receptor density showed the greatest decrease in rate.

Radionuclides in fishes and mussels from the Farallon Islands Nuclear Waste Dump Site, California.

The Farallon Islands Nuclear Waste Dump Site (FINWDS), approximately 30 miles west of San Francisco, California, received at least 500 TBq encapsulated in more than 47,500 containers from approximately 1945 to 1970. During several seasons in 1986/87 deep-sea bottom feeding fishes (Dover sole = Microstomus pacificus; sablefish = Anoplopoma fimbria; thornyheads = Sebastolobus spp.) and intertidal mussels (Mytilus californianus) were collected from the vicinity of the FINWDS and from comparable depths at a reference site near Point Arena, CA. Tissues were analyzed for several radionuclides (137Cs, 238Pu, 239+240Pu, and 241Am). Radionuclide concentrations for fish mussel tissue ranged from non-detectable to 4,340 mBq kg(-1) wet weight, with the following means for Farallon fishes: 137Cs = 1,110 mBq kg(-1); 238Pu = 390 mBq kg(-1); 239+240Pu = 130 mBq kg(-1); and 241Am = 1,350 mBq kg(-1). There were no statistically significant differences in the radionuclide concentrations observed in samples from the Farallon Islands compared to reference samples from Point Arena, CA. Concentrations of both 238Pu and 241Am in fish tissues (from both sites) were notably higher than those reported in literature from any other sites world-wide, including potentially contaminated sites. Concentrations of 239+24OPu from both sites were typical of low values found at some contaminated sites worldwide. These results show approximately 10 times higher concentrations of 239+240Pu and approximately 40-50 times higher concentrations of 238Pu than those values reported for identical fish species from 1977 collections at the FINWDS. Radionuclide concentrations were converted to a hypothetical per capita annual radionuclide intake for adults, yielding the following values of annual Committed Effective Dose Equivalent (CEDE) from ionizing radiation emitted from these radionuclides: 0.000 mSv y(-1) for 137Cs, 0.009 mSv Y(-1) for 228Pu, and 0.003 mSv y(-1) for 239+240Pu. For 241Am, projected CEDE for Dover sole, sablefish, and thornyheads were higher, averaging 0.03 mSv y(-1). The observed isotopic ratio of 238Pu/239+240Pu was about 4 (which is two orders of magnitude higher than the ratio of 0.03 associated with fallout from weapons tests and accidental releases in the north temperate zone of the earth), indicating a considerably higher environmental mobilization for 238Pu compared to 239+240Pu. Likewise, the observed ratio of 241Am/239+240Pu of about 30 was nearly two orders of magnitude higher than the fallout ratio of 0.43 in the north temperate zone of the earth. The projected ionizing radiation CEDE to people from the ingestion of fish with fallout radionuclides was three times higher for 241Am than from the plutonium isotopes.

[Bibliometric indicators, subjects analysis and methodology of research published in Spain on epidemiology and public health care (1988-1992)]. / Indicadores bibliométricos, análisis temático y metodológico de la investigación publicada en España sobre epidemiología y salud pública (1988-1992).

BACKGROUND: To describe Spanish scientific output in epidemiology and public health through the bibliometric indexes utilization and with regard to subjects, design and statistical methods employed, as well as its appropriateness, importance and funding. MATERIAL AND METHODS: Descriptive, longitudinal and retrospective study over 594 originals published in Spanish medical journals and listed in the Spanish Medical Index (Indice Médico Español) during the 5 years period 1988-1992. RESULTS: The average autors by article was of 4.9 and the Lotka's index, for the authors that publish articles on the topic, was -2.92; 82% of the authors have a productivity index equal to zero. Almost 70% of the articles are signed by an isolated institution, being a hospital in 51% of the cases. The journal that publishes most articles on the topic is Medicina Clínica. The average references by article is about 24. The Price' index is 36.5% and the isolation' index is 36.2%. "The non AIDS infections", the descriptive designs and the lack of inferential statistics methods, characterize the content of the articles. Regarding to the criteria established by the study, more than half of the analyzed research (56.5%) was appropriate and almost a fourth (22%) could be considered that was about important topics. CONCLUSIONS: Concerning bibliometric indicators, research on epidemiology and public health in Spain does not seem to differ from other medical specialties. The epidemiology as scientific method is widely used over the medical specialties, something which could explain the wide dispersion of scientific literature on this topic. There seems to be a certain lack of agreement between the research topics and the real health problems of Spain.