A fully automatic method for vascular tortuosity feature extraction in the supra-aortic region: unraveling possibilities in stroke treatment planning

Vascular tortuosity of supra-aortic vessels is widely considered one of the main reasons for failure and delays in endovascular treatment of large vessel occlusion in patients with acute ischemic stroke. Characterization of tortuosity is a challenging task due to the lack of objective, robust and effective analysis tools. We present a fully automatic method for arterial segmentation, vessel labelling and tortuosity feature extraction applied to the supra-aortic region. A sample of 566 computed tomography angiography scans from acute ischemic stroke patients (aged 74.8 ± 12.9, 51.0% females) were used for training, validation and testing of a segmentation module based on a U-Net architecture (162 cases) and a vessel labelling module powered by a graph U-Net (566 cases). Successively, 30 cases were processed for testing of a tortuosity feature extraction module. Measurements obtained through automatic processing were compared to manual annotations from two observers for a thorough validation of the method. The proposed feature extraction method presented similar performance to the inter-rater variability observed in the measurement of 33 geometrical and morphological features of the arterial anatomy in the supra-aortic region. This system will contribute to the development of more complex models to advance the treatment of stroke by adding immediate automation, objectivity, repeatability and robustness to the vascular tortuosity characterization of patients.

A semi-empirical model for scatter field reduction in digital mammography

X-ray mammography is the gold standard technique in breast cancer screening programmes. One of the main challenges that mammography is still facing is scattered radiation, which degrades the quality of the image and complicates the diagnosis process. Anti-scatter grids, the main standard physical scattering reduction technique, have some unresolved challenges as they increase the dose delivered to the patient, do not remove all the scattered radiation and increase the cost of the equipment. Alternative scattering reduction methods based on post-processing algorithms, have lately been under investigation. This study is concerned with the use of image post-processing to reduce the scatter contribution in the image, by convolving the primary plus scatter image with kernels obtained from simplified Monte Carlo (MC) simulations. The proposed semi-empirical approach uses up to five thickness-dependant symmetric kernels to accurately estimate the scatter contribution of different areas of the image. Single breast thickness-dependant kernels can over-estimate the scatter signal up to 60%, while kernels adapting to local variations have to be modified for each specific case adding high computational costs. The proposed method reduces the uncertainty to a 4%-10% range for a 35-70 mm breast thickness range, making it a very efficient, case-independent scatter modelling technique. To test the robustness of the method, the scattered corrected image has been successfully compared against full MC simulations for a range of breast thicknesses. In addition, clinical images of the 010A CIRS phantom were acquired with a mammography system with and without the presence of the anti-scatter grid. The grid-less images were post-processed and their quality was compared against the grid images, by evaluating the contrast-to-noise ratio and variance ratio using several test objects, which simulate calcifications and tumour masses. The results obtained show that the method reduces the scatter to similar levels than the anti-scatter grids.

Are artificial intelligence systems useful in breast cancer screening programs?

Population-based breast cancer screening programs are efficacious in reducing the mortality due to breast cancer. These programs use mammography to screen the women who are invited to participate. Digital mammography makes it possible to develop computer-assisted diagnosis (CAD) systems that promise to reduce the workload of radiologists participating in screening programs. However, various studies have shown that CAD results in a high rate of false positive diagnoses. Systems based on artificial intelligence are being more widely implemented, and studies have shown that these systems have better diagnostic performance than traditional CAD systems. This article explains the fundamentals of artificial intelligence systems and an overview of possible applications of these systems within the framework of breast cancer screening programs.

Photosynthetic bacteria-based membrane bioreactor as post-treatment of an anaerobic membrane bioreactor effluent

Anaerobic membrane bioreactors have attracted increasing interest in the field of wastewater treatment. However, significant amounts of organic matter, nitrogen and sulphide in the effluent may limit its reuse. A photosynthetic bacteria-based membrane bioreactor is proposed for the further treatment of this effluent. A pilot-scale unit was run outdoor for over 900h to assess the process performance at short hydraulic retention time. After an initial biomass development, simultaneous removal of soluble organic matter and nitrogen was achieved (65% and 39%, respectively). In addition, a significant concentration of sulphate was detected in the permeate, revealing an evident sulphide oxidation. Despite the accumulation of biopolymer clusters in the biological suspension, membrane fouling was effectively mitigated by air-aided backwashing, allowing a sustainable operation. Several strains of bacteria were identified including the photoheterotrophic bacteria Rhodopseudomonas sp. and the nitrifying and denitrifying bacteria Chryseobacterium sp.

Genetic and Biological Characterization of Four Nucleopolyhedrovirus Isolates Collected in Mexico for the Control of Spodoptera exigua (Lepidoptera: Noctuidae)

This study describes four multiple nucleocapsid nucleopolyhedrovirus isolates recovered from infected larvae of beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), on crops in two different geographical regions of Mexico. Molecular and biological characterization was compared with characterized S. exigua multiple nucleopolyhedrovirus (SeMNPV) isolates from the United States (SeUS1 and SeUS2) and Spain (SeSP2). Restriction endonuclease analysis of viral DNA confirmed that all Mexican isolates were SeMNPV isolates, but molecular differences between the Mexican and the reference isolates were detected using PCR combined with restriction fragment length polymorphism (RFLP). Amplification of the variable region V01 combined with RFLP distinguished the two Mexican isolates, SeSLP6 and SeSIN6. BglII digestions showed that the majority of the isolates contained submolar bands, indicating the presence of genetic heterogeneity. Amplification of the variable regions V04 and V05 distinguished between American and the Spanish isolates. Biological characterization was performed against two laboratory colonies of S. exigua, one from Mexico, and another from Switzerland. Insects from the Mexican colony were less susceptible to infection than insects from Se-Swiss colony. In the Se-Mex colony, SeSP2 was the most pathogenic isolate followed by SeSIN6, although their virulence was similar to most of the isolates tested. In Se-Swiss colony, similar LD50 values were observed for the five isolates, although the virulence was higher for the SeSLP6 isolate, which also had the highest OB (occlusion body) yield. We conclude that the Mexican isolates SeSIN6 and SeSLP6 possess insecticidal traits of value for the development of biopesticides for the control of populations of S. exigua.

Total and bioavailable arsenic concentration in arid soils and its uptake by native plants from the pre-Andean zones in Chile

Arsenic is the most important contaminant of the environment in northern Chile. Soil samples and plant organs from three native plant species, Pluchea absinthioides, Atriplex atacamensis and Lupinus microcarpus, were collected from arid zones in order to determine the total and bioavailable arsenic concentrations in soils and to assess the bioconcentration factor (BCF) and transport index (Ti) of arsenic in the plants. Total arsenic concentrations in soils (pH 8.3-8.5) where A. atacamensis and P. absinthioides were collected, reached levels considered to be contaminated (54.3 ± 15.4 and 52.9 ± 9.9 mg kg⁻¹, respectively), and these values were approximately ten times higher than in soils (pH 7.6) where L. microcarpus was collected. Bioavailable arsenic ranged from 0.18 to 0.42% of total arsenic concentration. In the three plant species, arsenic concentration in leaves were significantly (p ≤ 0.05) higher than in roots. L. microcarpus showed the highest arsenic concentration in its leaves (9.7 ± 1.6 mg kg⁻¹) and higher values of BCF (1.8) and Ti (6.1), indicating that this species has a greater capacity to accumulate and translocate the metalloid to the leaf than do the other species.

Lethal and sublethal effects of methoxyfenozide on the development, survival and reproduction of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

The lethal and sublethal effects of the ecdysone agonist methoxyfenozide on the fall armyworm, Spodoptera frugiperda (J. E. Smith), were investigated by feeding a methoxyfenozide-treated diet to fifth instars until pupation in doses corresponding to the LC10 and LC25 for the compound. Larval mortality reached 8% and 26% in the low and high concentration groups, respectively, on the seventh day of the experiment. A progressive larval mortality of 12% for the LC10 and 60% for the LC25 was observed before pupation. Treated larvae exhibited lower pupal weights, higher pupal mortality, presence of deformed pupae, and more deformed adults than untreated larvae. The incorporation of methoxyfenozide into the diet had a significant effect on the timing of larval development. The development period for males and females was about seven days longer than the controls for both concentrations tested. In contrast, the compound affected neither pupae nor adult longevity. Finally, S. frugiperda adults that resulted from fifth instars treated with methoxyfenozide were not affected in their mean cumulative number of eggs laid per female (fecundity), nor percentages of eggs hatched (fertility), or the sex ratio. Our results suggest that the combination of lethal and sublethal effects of methoxyfenozide may have important implications for the population dynamics of the fall armyworm.

Impact of the introduction of rapid HIV testing in the Voluntary Counselling and Testing sites network of Catalonia, Spain

Summary

Rapid HIV antibody tests, which provide results within 15–60 minutes, can help reduce the number of unrecognized infections by improving access to testing facilities and increase the number of people tested who know their results. After an acceptability study, rapid HIV testing was first implemented in Catalonia in 2007 within the community-based Voluntary Counselling and Testing sites network. One year after implementation, an increase of 102.9% has been observed in the number of tests performed, ranging from 8.4% to 328.3% according to the site. Despite the important immediate impact of rapid HIV testing on the number of tests performed, there was no significant change in the proportion of tests that were positive. Rapid HIV testing can help increase access to testing, but it should be complemented with specific outreach programmes targeting the most vulnerable subgroups.

Prevalence of overweight and obesity among preadolescent schoolchildren in Galicia, Spain

BACKGROUND

Childhood obesity is rising rapidly in many countries. Preadolescents appear to be at particularly high risk. This study estimated the prevalence of overweight and obesity in preadolescent schoolchildren in Galicia, Spain.

METHODS

The heights and weights of a random sample of 2305 Galician schoolchildren aged 10-12 years were measured using calibrated standardized scales and measures. Overweight and obesity were identified using the criteria of the International Obesity Task Force.

RESULTS

The prevalences of obesity and overweight were respectively 9.2% and 31.0% among boys, 8.6% and 28.8% among girls and 8.9% and 29.9% overall. Taking boys and girls together, the combined prevalence of overweight and obesity fell significantly with increasing age. Overweight was more prevalent in rural than urban areas (30.7% vs. 28.4%), as also was obesity (9.8% vs. 7.2%).

CONCLUSIONS

Our study evidences the emergence of the obesity epidemic among preadolescents in Galicia, especially in rural areas. Both overweight and obesity in this age group are more prevalent in Galicia than in other areas of Spain or most other Western nations.

Sex differences in mortality in patients with COPD

Little is known about survival and clinical prognostic factors in females with chronic obstructive pulmonary disease (COPD). The aim of the present study was to determine the survival difference between males and females with COPD and to compare the value of the different prognostic factors for the disease. In total, 265 females and 272 males with COPD matched at baseline by BODE (body mass index, airflow obstruction, dyspnoea, exercise capacity) and American Thoracic Society/European Respiratory Society/Global Initiative of Chronic Obstructive Lung Disease criteria were prospectively followed. Demographics, lung function, St George's Respiratory Questionnaire, BODE index, the components of the BODE index and comorbidity were determined. Survival was documented and sex differences were determined using Kaplan-Meier analysis. The strength of the association of the studied variables with mortality was determined using multivariate and receiver operating curves analysis. All-cause (40 versus 18%) and respiratory mortality (24 versus 10%) were higher in males than females. Multivariate analysis identified the BODE index in females and the BODE index and Charlson comorbidity score in males as the best predictors of mortality. The area under the curve of the BODE index was a better predictor of mortality than the forced expiratory volume in one second for both sexes. At similar chronic obstructive pulmonary disease severity by BODE index and forced expiratory volume in one second, females have significantly better survival than males. For both sexes the BODE index is a better predictor of survival than the forced expiratory volume in one second.

Physiological and clinical effects of diurnal noninvasive ventilation in hypercapnic COPD

To assess the clinical impact of noninvasive mechanical ventilation (NIMV) on stable hypercapnic chronic obstructive pulmonary disease, changes in exercise capacity, dyspnoea and simple physiological parameters were evaluated. The time course of these effects during treatment and recovery was also assessed. Patients were randomly allocated to NIMV (n=27) or sham-NIMV (n=15), applied 3 h.day-1, 5 days a week, for 3 weeks. A 6-min walking distance (6MWD), arterial blood gases, spirometry, pattern of breathing, mouth occlusion pressure (P0.1), and respiratory system impedance (P0.1/tidal volume (VT)/inspiratory time (tI)) were measured weekly during treatment and 2 weekly during follow-up. Transition dyspnoea index (TDI) was also measured. During NIMV, carbon dioxide arterial tension decreased progressively, concomitantly with a slow deep pattern of breathing, a proportional increase in the forced expiratory volume in one second (FEV1), the forced vital capacity and significant reductions of P0.1 and P0.1/VT/tI. The 6MWD improved by a mean of 76 m after NIMV, and by 73 m and 61 m 1 and 2 weeks, respectively, after treatment. Dyspnoea improved with a mean TDI of three points. Changes in 6MWD were highly related to TDI and to a lesser extent to changes in FEV1 (r=0.60). The current authors conclude that noninvasive mechanical ventilation has significant and sustained clinical impact in stable hypercapnic chronic obstructive pulmonary disease.

Shielding analysis of the Microtron MT-25 bunker using the MCNP-4C code and NCRP Report 51

A cyclic electron accelerator Microtron MT-25 will be installed in Havana, Cuba. Electrons, neutrons and gamma radiation up to 25 MeV can be produced in the MT-25. A detailed shielding analysis for the bunker is carried out using two ways: the NCRP-51 Report and the Monte Carlo Method (MCNP-4C Code). The walls and ceiling thicknesses are estimated with dose constraints of 0.5 and 20 mSv y(-1), respectively, and an area occupancy factor of 1/16. Both results are compared and a preliminary bunker design is shown.

Effects of noninvasive ventilation on lung hyperinflation in stable hypercapnic COPD

Two previous uncontrolled studies have suggested that noninvasive mechanical ventilation (NIMV) in patients with hypercapnic chronic obstructive pulmonary disease (COPD) improves arterial blood gas tensions by decreasing lung hyperinflation with the consequent reduction in inspiratory loads and changes in ventilatory pattern. The aim of this randomised placebo-controlled study was to determine whether these mechanisms play a pivotal role in the effects of NIMV on arterial blood gases. Thirty-six stable hypercapnic COPD patients were randomly allocated to NIMV or sham NIMV. A 2-week run-in period was followed by a 3-week study period, during which ventilation was applied 3 h x day(-1), 5 days a week. Arterial blood gases, spirometry, lung volumes, and respiratory mechanics were measured before and after application of NIMV. Patients submitted to NIMV showed changes (mean (95% confidence interval)) in daytime arterial carbon dioxide tension (Pa,CO2) and arterial oxygen tension of -1.12 (-1.52-0.73) kPa (-8.4 (-11.4-5.5) mmHg) and 1.14 (0.70-1.50) kPa (8.6 (5.3-11.9) mmHg), respectively. Total lung capacity, functional residual capacity (FRC) and residual volume were found to be reduced by 10 (7-13), 25 (18-31), and 36 (27-45)% of their predicted value, respectively, whereas forced expiratory volume in one second and forced vital capacity increased by 4 (1.5-6.9) and 9 (5-13)% pred, respectively. Tidal volume (VT) increased by 181 (110-252) mL. All of the above changes were significant compared with sham NIMV. Changes in Pa,CO2 were significantly related to changes in dynamic intrinsic positive end-expiratory pressure, inspiratory lung impedance, VT and FRC. It was concluded that the beneficial effects of noninvasive mechanical ventilation could be explained by a reduction in lung hyperinflation and inspiratory loads.

In vivo drug resistance of falciparum malaria in mining areas of Venezuela

The Lot Quality Assurance Double-Sampling Plan (LQADSP) technique was used in three areas, Maripa, Kilómetro 88 and Ikabaru, to assess the efficacy of antimalarials used routinely by the Venezuelan Malaria Programme. The use of chloroquine (25 mg/kg), chloroquine (40 mg/kg) and the combination of sulfadoxine (500 mg) and pyrimethamine (25 mg) registered treatment failures above the threshold level of 25% in Maripa and Kilómertro 88. In Ikabaru the use of chloroquine (40 mg/kg) did not surpass that quality level and could possibly be less than 10%. Quinine (30 mg/kg) was totally effective in curing patients in all three areas. The use of this technique seems adequate for rapid field evaluations and in this case for providing appropriate information to assist this health programme. However, whilst being an ideal technique for surveying areas in which considerable variation may exist among lots and particularly for Plasmodium falciparum infections in these areas, repeated surveys should be carried out in the same areas over time to monitor changes in the susceptibility of this parasite to first-, second- and third-line drugs. In that way, national drug policies can be modified adequately.

Extent and patterns of RAPD variation in landraces and cultivars of rye (Secale cereale L.) from northern Europe

Little is known about the extent and patterns of distribution of RAPD diversity in outcrossing species. This study is the first step in using RAPD markers to quantify the amount and distribution of genetic variation within and between accessions of 9 landraces and 3 cultivars of cultivated rye from Northern Europe. A high level of RAPD variation was detected, demonstrating the utility of RAPDs for genetic characterisation in rye. The results show that: (1) landraces and improved cultivars maintain roughly the same high levels of RAPD variation, (2) landraces from Norway, Germany and Finland showed the lowest level of variation, probably because of a small amount of seeds from the original samples, (3) most of the RAPD variation was found within rather than between the accessions, which is consistent with the pattern expected for a cross pollinated crop. Both the cluster and the principal coordinates analyses displayed the same pattern of genetic relationship among the accessions studied.

Parathion induces mouse germ cells apoptosis

Germ cell loss occurs in normal spermatogenesis at defined stages of the seminiferous epithelial cycle. The process has been known for over a century but only recently it was analyzed under the concept of apoptosis. This is a programmed cell death that occurs during development and also in the adult. It is believed to play a key role as quality control in sperm formation, avoiding the passage of genetic defects to future generations. Chemical toxicants may increase apoptosis, disturbing tissue homeostasis. The effect of the agropesticide parathion upon apoptosis in mouse seminiferous tubules was analyzed in young mice (onset of spermatogenesis) and in adult animals (full spermatogenesis). In both young and adult mice, the pesticide increases the rate of apoptosis, which takes place at stages where spermatogonial proliferation occurs, affects spermatocytes at the beginning of the meiotic process and spermatids at the elongating period. Basal apoptotic rates are greater in young mice. In adults, commercial parathion is more toxic than the pure organophosphoric compound. From these observations plus in vitro effects of parathion reported previously, it can be concluded that the pesticide affects DNA (and RNA and protein) synthesis. The effect is reversible with moderate doses of the chemical after acute intoxication.

[The six minute walking test elicits lung hyperinflation in patients with severe chronic obstructive lung disease]

BACKGROUND

Exercise tolerance in patients with COPD is highly variable and poorly related to airways obstruction assessed by FEV1. These patients develop dynamic hyperinflation (DH) during an incremental exercise test which can be evaluated through a reduction in inspiratory capacity (IC).

AIM

To evaluate: a) if the six minute walking test (6 MWD) induce DH reducing IC, b) if the reduction in IC is related to tidal expiratory flow limitation at rest (FL).

SUBJECTS AND METHODS

Thirty eight stable COPD patients (28 FL and ten non FL during resting breathing, determined by the negative pressure technique). Inspiratory capacity was measured before and immediately after the 6 MWD test. Dyspnea, SpO2 and heart rate were measured before and after the test.

RESULTS

Inspiratory capacity was lower in FL patients as compared to patients without FL (p < 0.005). Although no differences were found between groups in 6 MWD, dyspnea and HR, a significant reduction in IC after the walking test was observed only in FL patients (p < 0.0001). In addition, SpO2 fell significantly (p < 0.0001) after walking in the same group.

CONCLUSIONS

Our results demonstrate that a moderate exercise such as the walking test induces DH and hypoxemia in patients with COPD and FL and stresses the importance of assessing DH by measuring IC in these patients.

Breathing pattern and gas exchange at peak exercise in COPD patients with and without tidal flow limitation at rest

Expiratory flow limitation (FL) at rest is frequently present in chronic obstructive pulmonary disease (COPD) patients. It promotes dynamic hyperinflation with a consequent decrease in inspiratory capacity (IC). Since in COPD resting IC is strongly correlated with exercise tolerance, this study hypothesized that this is due to limitation of the maximal tidal volume (VT,max) during exercise by the reduced IC. The present study investigated the role of tidal FL at rest on: 1) the relationship of resting IC to VT,max; and 2) on gas exchange during peak exercise in COPD patients. Fifty-two stable COPD patients were studied at rest, using the negative expiratory pressure technique to assess the presence of FL, and during incremental symptom-limited cycling exercise to evaluate exercise performance. At rest, FL was present in 29 patients. In the 52 patients, a close relationship of VT,max to IC was found using non-normalized values (r=0.77; p < 0.0001), and stepwise regression analysis selected IC as the only significant predictor of VT,max. Subgroup analysis showed that this was also the case for patients both with and without FL (r=0.70 and 0.76, respectively). In addition, in FL patients there was an increase (p < 0.002) in arterial carbon dioxide partial pressure at peak exercise, mainly due to a relatively low VT,max and consequent increase in the physiological dead space (VD)/VT ratio. The arterial oxygen partial pressure also decreased at peak exercise in the FL patients (p < 0.05). In conclusion, in chronic obstructive pulmonary disease patients the maximal tidal volume, and hence maximal oxygen consumption, are closely related to the reduced inspiratory capacity. The flow limited patients also exhibit a significant increase in arterial carbon dioxide partial pressure and a decrease in arterial oxygen partial pressure during peak exercise.

[Selective training of respiratory muscles in patients with chronic heart failure]

BACKGROUND

Patients with chronic heart failure have a lower inspiratory muscle strength and fatigue endurance.

AIM

To assess the effects of selective training of respiratory muscles in patients with heart failure.

PATIENTS AND METHODS

Twenty patients with stable chronic heart failure, aged 58.3 +/- 3 years with an ejection fraction of 28 +/- 9%, were subjected to respiratory muscle training with threshold valves. The load was fixed in 30% of maximal inspiratory pressure (PImax) in 11 and in 10% of PImax in nine. Two sessions of 15 minutes, 6 days per week, during 6 weeks were done. Degree of dyspnea (Mahler score), maximal oxygen uptake, distance walked in 6 minutes, respiratory muscle function and left ventricular ejection fraction were measured before and after training.

RESULTS

Both training loads were associated to an improvement in dyspnea (+2.7 +/- 1.8 and +2.8 +/- 1.8 score points with 30% PImax and 10% PImax respectively), maximal oxygen uptake (from 19 +/- 3 to 21.6 +/- 5 and from 16 +/- 5 to 18.6 +/- 7 ml/kg/min with 30% PImax and 10% PImax respectively, p < 0.05), PImax (from 78 +/- 22 to 99 +/- 22 and from 72 +/- 34 to 82.3 cm H20 with 30% PImax and 10% PImax respectively), sustained PImax (from 63 +/- 18 to 90 +/- 22 and from 58 +/- 3 to 69 +/- 3 cm H20 with 30% PImax and 10% PImax respectively), and maximal sustained load (from 120 +/- 67 to 195 +/- 47 and from 139 +/- 120 to 192 +/- 154 g with 30% PImax and 10% PImax respectively). The distance walked in 6 min only increased in subjects trained at 30% PImax (from 451 +/- 78 to 486 +/- 68 m).

CONCLUSIONS

Selective training of respiratory muscles results in a functional improvement of patients with chronic heart failure.

Patterns and levels of genetic differentiation in North American populations of the Alaskan wheatgrass complex

Levels and distribution of genetic variation were assessed using six allozymes in 27 populations of Alaskan wheatgrass (Elymus alaskanus) from different locations in Canada, USA, Greenland and Russia to obtain information on the genetic structure of these populations. The enzyme systems were ACO, DIA, GPI, MDH, PGM and SKD. Allozyme variation at the species level was high, with 64.3% (Ps) of the loci being polymorphic, an average number of alleles per locus of 1.9 (As), and an average genetic diversity of 0.17 (Hes). Differentiation was found in the populations studied, with the following findings: (1) statistically significant differences were found in allele frequencies among populations for every polymorphic locus (P < 0.001); (2) 63% of the total allozyme variation at polymorphic loci was partitioned among populations (GST = 0.63); (3) relatively low mean genetic distances between the populations were obtained (mean D = 0.029); (4) the genetic structure of Russian populations are clearly distinct from the other populations, the cluster and principal component analyses revealed the same genetic patterns of relationships among populations. This study also indicates that E. alaskanus contains different levels of allozyme variation in its populations. Furthermore, some banding patterns at the loci Aco-1, Aco-2, Gpi-2, Mdh-1, Skd-1, Skd-2 can be used as markers to identify individual populations.

[Quality of life in patients with chronic obstructive pulmonary disease and the impact of physical training]

BACKGROUND

Health related quality of life (QoL) is severely impaired in COPD patients as a consequence of dyspnea and limited exercise tolerance, which lead to physical deconditioning and muscle atrophy resulting in weakness and fatigue. Psychosocial factors such as depression and anxiety also contribute to this impairment.

AIM

To evaluate: a) the impact of COPD on quality of life, and b) the effect of 10 weeks of exercise training on exercise performance and on QoL.

PATIENTS AND METHODS

The Spanish version of the Chronic Respiratory Questionnaire (CRQ) was applied to 55 COPD patients (FEV1 37 +/- 13% pred) for the assessment of QoL and in 30 of them submitted to exercise training for 10 weeks. Exercise performance was evaluated by measuring: six-minute walking distance, maximal workload (Wmax), maximal O2 consumption (VO2max) as well as endurance time, blood lactic acid, dyspnea and leg fatigue during a submaximal exercise. Trained patients were evaluated before and after training.

RESULTS

COPD patients showed a reduction (mean +/- SD) in the four domains of the CRQ: dyspnea (3.1 +/- 0.9); fatigue (4.3 +/- 1.3); mastery (4.65 +/- 1.3), emotional function (4.1 +/- 0.97), and in Wmax and VO2max (52 +/- 16 Watt and 970 +/- 301 ml/min). No significant relationship between the impairment in exercise tolerance and in QoL was observed. Exercise training significantly improved the four domains of QoL (p < 0.0001), Wmax (p < 0.05), VO2max (p < 0.02) and endurance time (p < 0.001). Isotime exercise measurements of dyspnea, leg fatigue and lactic acid decreased after training (p < 0.001, each). No significant relation between changes in QoL and changes in exercise performance were observed.

CONCLUSIONS

Our results demonstrate that QoL is seriously impaired in patients with COPD and confirm: (a) the lack of relationship of QoL to the usually measured physiological parameters, and (b) the beneficial effect of exercise training on QoL through the reduction of symptoms. These findings stresses the need of measuring quality of life in our patients if we want to evaluate the impact of therapeutic procedures on well-being from the patients' perspective.

[Toxic epidermal necrolysis. Therapy in ICU with intravenous immunoglobulins in a case]

We report a 27 years old homosexual male with AIDS that was admitted to the ICU dehydrated, with fever and severe malaise. He had irregular bullae, an extensive purpuric exanthema and a zone of epidermic detachment in the right arm. A toxic epidermal necrolysis was diagnosed and therapy with i.v. immunoglobulins was started. After four days of treatment, bullous lesions disappeared and the extension of exanthema decreased. Toxic epidermal necrolysis is a potentially fatal disease and the use of intravenous immunoglobulins for this condition has been reported as successful.

[Non-invasive mechanical ventilation in patients with severe stable COPD]

BACKGROUND

The benefits of non-invasive mechanical ventilation (NIMV) in hypercapnic patients with severe stable COPD remain controversial mainly due to their unknown mechanisms.

AIM

To assess the clinical and physiological benefits of a 3 weeks period of intermittent NIMV and their underlying mechanisms in COPD patients.

PATIENTS AND METHODS

Twelve patients (10 male) prospectively recruited (age 65 +/- 3 years, FEV1 27 +/- 2% predicted, PaO2 46 +/- 2 mmHg, PaCO2 55 +/- 2 mmHg) were submitted to NIMV using a commercially available system (BiPAP) 3 h a day, 5 days a week for 3 weeks. Arterial blood gases, 6 min walking distance, dyspnea (Mahler's scale), breathing pattern, PIMax, ventilatory drive (P0.1) and the impedance of the respiratory system (P0.1/V1/T1) were measured before and after NIMV.

RESULTS

A significant improvement in PaO2, PaCO2, PIMax, dyspnea and exercise capacity was observed in addition to a trend for VT to increase and for respiratory rate (RR) to decrease. The impedance of the respiratory system showed a significant reduction. Ventilatory drive, normalized for PaCO2 levels, did not change. Improvement in PaCO2 was related to an increase in Vp whereas a significant association between the reduction in RR and the fall in respiratory system impedance was also found.

CONCLUSIONS

Our study supports previous data demonstrating that NIMV improves clinical and physiologic parameters in advanced stable COPD and suggest that the underlying mechanism is a reduction in the inspiratory load. A randomized clinical trial is needed to confirm that this mechanism is operative.

Genetic diversity in Elymus caninus as revealed by isozyme, RAPD, and microsatellite markers

Genetic diversity of 33 Elymus caninus accessions was investigated using isozyme, RAPD, and microsatellite markers. The three assays differed in the amount of polymorphism detected. Microsatellites detected the highest polymorphism. Six microsatellite primer pairs generated a total of 74 polymorphic bands (alleles), with an average of 15.7 bands per primer pair. Three genetic similarity matrices were estimated based on band presence or absence. Genetic diversity trees (dendrograms) were derived from each marker technique, and compared using Mantel's test. The correlation coefficients were 0.204, 0.267, and 0.164 between isozyme and RAPD distance matrices, RAPD and microsatellite distance matrices, and between isozyme and microsatellite distance matrices, respectively. The three methodologies gave differing views of the amount of variation present but all showed a high level of genetic variation in E. caninus. The following points may be drawn from this study whether based on RAPD, microsatellite, or isozyme data: (i) The Icelandic populations are consistently revealed by the three dendrograms. The congruence of the discrimination of this accession group by RAPD, microsatellite, and isozyme markers suggests that geographic isolation strongly influenced the evolution of the populations; (ii) The degree of genetic variation within accessions was notably great; and (iii) The DNA-based markers will be the more useful ones in detecting genetic diversity in closely related accessions. In addition, a dendrogram, which took into account all fragments produced by isozymes, RAPDs, and microsatellites, reflected better the relationships than did dendrograms based on only one type of marker.

Use of methylene blue in patients with refractory septic shock: impact on hemodynamics and gas exchange

PURPOSE

The purpose of this study was to assess the acute effects of methylene blue, an inhibitor of nitric oxide synthesis, on hemodynamics and gas exchange in patients with refractory septic shock in a prospective clinical trial at medical and surgical intensive care units in a tertiary university hospital.

PATIENTS AND METHODS

Prospective, sequential study of 10 consecutive patients admitted with severe septic shock of diverse causes and unable to achieve an adequate arterial pressure despite the use of at least two vasoactive drugs. Six of them also developed acute lung injury. All received 1 mg/kg intravenous bolus of methylene blue. Hemodynamic and respiratory parameters were measured at baseline and at 30, 60, 120, and 180 minutes after the bolus injection.

RESULTS

Systolic, diastolic, mean arterial blood pressure, and systemic vascular resistance increased significantly in all patients, whereas no significant changes were observed in cardiac output, oxygen consumption, or oxygen extraction ratio. Gas exchange remained unaffected in patients with acute lung injury.

CONCLUSIONS

Methylene blue had an acute vasopressor effect in patients with refractory septic shock, and it was not deleterious on respiratory function.

Invasive exercise testing in the evaluation of patients at high-risk for lung resection

The aim of this study was to investigate whether invasive exercise testing with gas exchange and pulmonary haemodynamic measurements could contribute to the preoperative assessment of patients with lung cancer at a high-risk for lung resection. Sixty-five patients scheduled for thoracotomy (aged 66+/-8 yrs (mean+/-SD), 64 males, forced expiratory volume in one second (FEV1) 54+/-13% predicted) were studied prospectively. High risk was defined on the basis of predicted postpneumonectomy (PPN) FEV1 and/or carbon monoxide diffusing capacity of the lung (DL,CO) <40% pred. Arterial blood gas measurements were performed in all patients at rest and during exercise. In 46 patients, pulmonary haemodynamic measurements were also performed at rest and during exercise. Predicted postoperative (PPO) values for FEV1 and DL,CO were calculated according to quantitative lung scanning and the amount of resected parenchyma. There were four postoperative deaths (6.2% mortality rate) and postoperative cardiorespiratory complications developed in 31 (47.7%) patients. Patients with respiratory complications only differed from patients without or with minimal (arrhythmia) complications in FEV1,PPO. Peak O2 uptake and haemodynamic variables were similar in both groups. The four patients who died had a lower FEV1,PPO, a lower DL,CO,PPO and a greater decrease in arterial oxygen tension during exercise, compared with the remaining patients. In conclusion, the forced expiratory volume in one second, together with the extent of parenchymal resection and perfusion of the affected lung, are useful parameters to identify patients at greatest risk of postoperative complications among those at a high-risk for lung resection. In these patients, pulmonary haemodynamic measurements appear to have no discriminatory value, whereas gas exchange measurements during exercise may help to identify patients with higher mortality risk.

Assessment of ventilation-perfusion mismatching in mechanically ventilated patients

The multiple inert gas elimination technique (MIGET) is a robust tool to assess both ventilation-perfusion (V'A/Q') distributions and the role of extrapulmonary factors determining arterial oxygenation during spontaneous breathing and in mechanically ventilated patients. Mixed expired gas sampling used in the MIGET is most often obtained from a 10-L mixing box (10L-MB) placed in the expiratory side of the ventilator circuit. Consequently, a considerable increase in the compression volume (Vc) would be expected which, in turn, can give rise to potential errors in the estimation of the effective tidal volume delivered to the patient. The effects of the 10L-MB on the Vc were compared with those produced by a newly designed 1-L, mixing box (IL-MB). At a given peak pressure (Ppeak) within the ventilator circuit, the Vc generated by the 10L-MB was about six-times higher than that produced by the 1L-MB. At a Ppeak =50 cmH2O, the Vc were 377 mL (10L-MB) and 67 mL (1L-MB) (p<0.001). In six patients, the mixed expired partial pressures of the six inert gases simultaneously collected from the two mixing boxes fell on the identity line. V'A/Q' distributions recovered using each of the two mixing boxes were equivalent. With the IL-MB, the effects of different positive end-expiratory pressure levels (0, 6 and 12 cmH2O) on Vc and arterial carbon dioxide tension were negligible. In conclusion, the new 1-L mixing box provides efficient gas mixing and substantially decreases the compression volume. It is, therefore, recommended when studies requiring mixed expired gas are performed in ventilated patients.

[Determination of complement-fixing antibodies to respiratory syncytial virus. Longitudinal study in a population of less than 1 year of age in the City of Havana]

Respiratory syncytial viruses (RSV) are considered among the most important agents causing acute respiratory infections in infants below 1 year of age. A 10-year longitudinal study of monosera from children under 15 years was carried out; 1,069 monosera from children under 1 year were studied using the RSV antigen complement-fixing technique. It was observed that there were short or longer periods between the peaks of positive sera and when they were compared with medical care reports, they showed correspondence with increased numbers of medical care reports. A typical seasonal pattern in the distribution of antibodies was determined and this corresponded to the month of February, suggesting that this is probably due to the circulation of the virus and not to maternal antibodies. The results attained give grounds for considering the possible circulation of RSV in our country.

[Study of the survival of elderly patients in intensive care units. Should they be admitted to these units?]

BACKGROUND

An important increase in health care costs has occurred lately, determined in part by the expenses of intensive care units. An important proportion of beds in these units are occupied by elders, with high costs and dubious results.

AIM

To study the survival of elderly patients in intensive care units to shed light on the question if these patients should be admitted to these facilities.

MATERIAL AND METHODS

We retrospectively analyzed the mortality of 443 patients older than 65 years old, admitted to an intensive care unit between 1993 and 1994. The mortality was compared with that of 334 younger patients admitted in the same period. Severity of disease was determined using admission APACHE II score.

RESULTS

Older patients had a higher admission APACHE score than younger subjects (18.4 +/- 8.4 and 14.5 +/- 8.7 respectively, p < 0.01). Mortality during the intensive care unit stay was similar in older and younger patients (18.5 and 14.4%, respectively). Hospital mortality was also similar (22.4 and 25.9%, respectively). Older patients had a higher frequency of chronic diseases and degree of functional impairment. Mortality rates for different diseases were also similar in older and younger patients.

CONCLUSIONS

Older age was not associated with a higher mortality during intensive care unit stay. Prognosis is determined by the admission severity score and the number of concomitant chronic diseases.

[Nitric oxide in respiratory diseases]

Recent reports have described a pathogenic role of nitric oxide in several respiratory disease. It is specially useful in the adult respiratory distress syndrome, where it acts as a selective vasodilator and improves gas exchange, decreasing pulmonary shunting. Although it has a proven bronchodilator effect, its therapeutic role in diseases such as asthma and chronic limitation of airway flow is not well defined. This article review the metabolism, mechanisms of action, potential uses and adverse effects of nitric oxide in respiratory disease.

Inhibition of PAF-induced gas exchange defects by beta-adrenergic agonists in mild asthma is not due to bronchodilation

Salbutamol inhibits neutropenia, increased airway resistance, and gas exchange abnormalities provoked by platelet-activating factor (PAF) challenge in normal persons. To further explore the intriguing dissociation between spirometric abnormalities and gas exchange defects shown in patients with asthma, we investigated whether the salbutamol-induced improvement in gas exchange disturbances after PAF is the result of bronchodilation by comparing this effect with that of ipratropium bromide. We hypothesized that ipratropium bromide, an anticholinergic agent without vascular effects, should block PAF-induced bronchoconstriction but not interfere with its systemic, neutropenic, and gas exchange effects. We studied eight nonsmokers with mild asthma (26 +/- 2.0 SE yr of age) who, prior to PAF challenge (18 micrograms), inhaled either ipratropium bromide (80 micrograms) or salbutamol (300 micrograms) in a randomized, double-blind, crossover fashion 1 wk apart. Peripheral blood neutrophils, respiratory system resistance (Rrs), arterial blood gases and ventilation-perfusion (VA/Q) inequalities were measured 5, 15, and 45 min after PAF. Compared with pretreatment with salbutamol, ipratropium bromide also blocked the increase of respiratory system resistance (Rrs) but did not prevent facial flushing and neutropenia (p < 0.03) at 5 min nor the decrease of PaO2 (p = 0.08 and 0.05), the increase of AaPO2 (p < 0.02 each), and the deterioration of VA/Q relationships (p < 0.05 each) at 5 and 15 min, respectively. This functional pattern was similar to that observed previously in normal subjects and in nonpremedicated asthmatic patients after PAF, with return to baseline values at 45 min. By contrast, salbutamol blocked PAF-induced increased Rrs, in addition to all the other PAF-induced abnormalities. These findings indicate that, in patients with mild asthma, salbutamol inhibits PAF-induced neutropenia and gas exchange abnormalities by mechanisms involving other than airway smooth muscle narrowing, possibly by acting on both the bronchial and pulmonary circulations.

Mechanisms of worsening gas exchange during acute exacerbations of chronic obstructive pulmonary disease

This study was undertaken to investigate the mechanisms that determine abnormal gas exchange during acute exacerbations of chronic obstructive pulmonary disease (COPD). Thirteen COPD patients, hospitalized because of an exacerbation, were studied after admission and 38+/-10 (+/-SD) days after discharge, once they were clinically stable. Measurements included forced spirometry, arterial blood gas values, minute ventilation (V'E), cardiac output (Q'), oxygen consumption (V'O2), and ventilation/perfusion (V'A/Q') relationships, assessed by the inert gas technique. Exacerbations were characterized by very severe airflow obstruction (forced expiratory volume in one second (FEV1) 0.74+/-0.17 vs 0.91+/-0.19 L, during exacerbation and stable conditions, respectively; p=0.01), severe hypoxaemia (ratio between arterial oxygen tension and inspired oxygen fraction (Pa,O2/FI,O2) 32.7+/-7.7 vs 37.6+/-6.9 kPa (245+/-58 vs 282+/-52 mmHg); p=0.01) and hypercapnia (arterial carbon dioxide tension (Pa,CO2) 6.8+/-1.6 vs 5.9+/-0.8 kPa (51+/-12 vs 44+/-6 mmHg); p=0.04). V'A/Q' inequality increased during exacerbation (log SD Q', 1.10+/-0.29 vs 0.96+/-0.27; normal < or = 0.6; p=0.04) as a result of greater perfusion in poorly-ventilated alveoli. Shunt was almost negligible on both measurements. V'E remained essentially unchanged during exacerbation (10.5+/-2.2 vs 9.2+/-1.8 L x min(-1); p=0.1), whereas both Q' (6.1+/-2.4 vs 5.1+/-1.7 L x min(-1); p=0.05) and V'O2 (300+/-49 vs 248+/-59 mL x min(-1); p=0.03) increased significantly. Worsening of hypoxaemia was explained mainly by the increase both in V'A/Q' inequality and V'O2, whereas the increase in Q' partially counterbalanced the effect of greater V'O2 on mixed venous oxygen tension (PV,O2). We conclude that worsening of gas exchange during exacerbations of chronic obstructive pulmonary disease is primarily produced by increased ventilation/perfusion inequality, and that this effect is amplified by the decrease of mixed venous oxygen tension that results from greater oxygen consumption, presumably because of increased work of the respiratory muscles.

The efficacy of laparoscopic surgery in the diagnosis and treatment of peritonitis. Experience with 107 cases in Mexico City

BACKGROUND

Peritonitis continues to be an important cause of morbidity and mortality and often an etiologic diagnosis is unclear. To evaluate the efficacy and safety of laparoscopy the authors analyzed their 5-year experience with this modality of treatment.

METHODS

A review was made of 107 consecutive nonselected laparoscopic procedures performed between October 1990 and November 1995. The diagnosis was established by clinical, laboratory, and imaging findings and confirmed by laparoscopy and/or laparotomy.

RESULTS

An etiologic diagnosis was unclear in 35% of the cases and was established in all by laparoscopy; 94 patients (87.9%) were successfully treated by laparoscopy while 13 (12.1%) required conversion. Mortality was 4.6%; 14% had postoperative complications and 7.4% had reoperations.

CONCLUSIONS

Laparoscopic surgery is safe and very efficient in the diagnosis and treatment of patients with peritonitis. In most instances a definitive treatment can be carried out without conversion and has the additional and well-known advantages of minimally invasive surgery.