Dynamical landscapes of cell fate decisions

The generation of cellular diversity during development involves differentiating cells transitioning between discrete cell states. In the 1940s, the developmental biologist Conrad Waddington introduced a landscape metaphor to describe this process. The developmental path of a cell was pictured as a ball rolling through a terrain of branching valleys with cell fate decisions represented by the branch points at which the ball decides between one of two available valleys. Here we discuss progress in constructing quantitative dynamical models inspired by this view of cellular differentiation. We describe a framework based on catastrophe theory and dynamical systems methods that provides the foundations for quantitative geometric models of cellular differentiation. These models can be fit to experimental data and used to make quantitative predictions about cellular differentiation. The theory indicates that cell fate decisions can be described by a small number of decision structures, such that there are only two distinct ways in which cells make a binary choice between one of two fates. We discuss the biological relevance of these mechanisms and suggest the approach is broadly applicable for the quantitative analysis of differentiation dynamics and for determining principles of developmental decisions.

Statistically derived geometrical landscapes capture principles of decision-making dynamics during cell fate transitions

Fate decisions in developing tissues involve cells transitioning between discrete cell states, each defined by distinct gene expression profiles. The Waddington landscape, in which the development of a cell is viewed as a ball rolling through a valley filled terrain, is an appealing way to describe differentiation. To construct and validate accurate landscapes, quantitative methods based on experimental data are necessary. We combined principled statistical methods with a framework based on catastrophe theory and approximate Bayesian computation to formulate a quantitative dynamical landscape that accurately predicts cell fate outcomes of pluripotent stem cells exposed to different combinations of signaling factors. Analysis of the landscape revealed two distinct ways in which cells make a binary choice between one of two fates. We suggest that these represent archetypal designs for developmental decisions. The approach is broadly applicable for the quantitative analysis of differentiation and for determining the logic of developmental decisions.

Simple template-based optimization for pediatric total lymphoid irradiation (TLI) radiotherapy treatments

Total lymphoid irradiation (TLI) is used in the management of pediatric allogeneic hematopoietic stem cell transplantation (HSCT. This work aims to simplify the treatment planning process for TLI via a proposed template using the volumetric modulated arc therapy (VMAT) technique. Fifteen pediatric patients were planned, prescribed to 8 Gy in 4 fractions. Cost functions included in the template were the ones for the planning target volume (PTV), and conformality cost function (CCF) for the rest of the patient's volume. Conformity index (CI), homogeneity index (HI), conformation number (CN), gradient index (GI), integral dose, and doses to the organs at risk achieved with the template were reported. Cost function influence over various indexes was studied by Wilcoxon signed ranks test. Same 15 patients were planned with 3-dimensional conventional radiotherapy (3D-CRT) technique for comparison. Mean CI and HI were 1.33 and 0.13, respectively, which indicates good dose conformation and homogeneity. Mean CN and GI values were 0.69 and 4.51, respectively. Mean PTV coverage was reached (V_100% > 95%). No correlation between the CCF and indexes values was found (p > 0.05). Doses to organs at risk (OARs) were as low as possible without losing PTV coverage. VMAT plan showed higher levels of conformation and similar homogeneity as 3D-CRT plans. Doses to OARs were inferior with VMAT except for the right kidney. The proposed template simplifies the planning of TLI treatments, and it is able to create acceptable plans with little modification in order to reduce doses to certain organs like the kidneys or the heart. VMAT technique showed higher conformation and lower doses to OAR compared to 3D-CRT.

TROPHY registry - status report

INTRODUCTION

The TROPHY registry has been established to conduct an international multicenter prospective data collection on the surgical management of neonatal intraventricular hemorrhage (IVH)-related hydrocephalus to possibly contribute to future guidelines. The registry allows comparing the techniques established to treat hydrocephalus, such as external ventricular drainage (EVD), ventricular access device (VAD), ventricular subgaleal shunt (VSGS), and neuroendoscopic lavage (NEL). This first status report of the registry presents the results of the standard of care survey of participating centers assessed upon online registration.

METHODS

On the standard of treatment forms, each center indicated the institutional protocol of interventions performed for neonatal post-hemorrhagic hydrocephalus (nPHH) for a time period of 2 years (Y1 and Y2) before starting the active participation in the registry. In addition, the amount of patients enrolled so far and allocated to a treatment approach are reported.

RESULTS

According to the standard of treatment forms completed by 56 registered centers, fewer EVDs (Y1 55% Y2 46%) were used while more centers have implemented NEL (Y1 39%; Y2 52%) to treat nPHH. VAD (Y1 66%; Y2 66%) and VSGS (Y1 42%; Y2 41%) were used at a consistent rate during the 2 years. The majority of the centers used at least two different techniques to treat nPHH (43%), while 27% used only one technique, 21% used three, and 7% used even four different techniques. Patient data of 110 infants treated surgically between 9/2018 and 2/2021 (13% EVD, 15% VAD, 30% VSGS, and 43% NEL) were contributed by 29 centers.

CONCLUSIONS

Our results emphasize the varying strategies used for the treatment of nPHH. The international TROPHY registry has entered into a phase of growing patient recruitment. Further evaluation will be performed and published according to the registry protocol.

Six-month Follow-up of the Effect of Nonvital Bleaching on IL-1β and RANK-L: A Randomized Clinical Trial

Objectives:

It has been reported that bleaching generates an increase in the activity of osteoclasts in vitro. We quantified the RANK-L and IL-1β biomarkers in a double-blind, randomized clinical trial evaluating the in vivo effect of hydrogen peroxide (35%) and peroxide carbamide (37%) six months after whitening.

Methods and Materials:

Fifty volunteers participated, each with color change in a nonvital tooth. Fifty teeth were randomly divided into two groups (n=25), and the teeth were bleached using either 35% hydrogen peroxide (G1) or 37% carbamide peroxide (G2). Intracoronal bleaching was carried out by a technical “walking bleach” over four sessions. Gingival crevicular fluid samples were collected and used to quantify the IL-1β and RANK-L secreted levels. Samples of six periodontal sites (three vestibular and three palatal) were collected for up to six months (at the beginning of the study [baseline] and at one week, one month, and six months posttreatment). The color change was visually monitored using the Vita Bleached Guide (ΔSGU).

Results:

Comparing each time to baseline assessment, a significant increase in the levels of IL-1β and RANK-L across time points was detected (p<0.05). The color change was 4 in G1 and G2, and a statistically significant difference (p<0.05) was found at the month time point between the groups. Using the Spearman test, a strong correlation (>0.8) between the IL-1β and RANK-L levels in both groups at all time points was detected.

Conclusions:

Nonvital bleaching using a technical walking bleach induces an increase in the IL-1β and RANKL production in periodontal tissues, which persists for six months after treatment. Both biomarkers were highly correlated in both groups and at all time points.

Will there be cold-related mortality in Spain over the 2021-2050 and 2051-2100 time horizons despite the increase in temperatures as a consequence of climate change?

INTRODUCTION

Global warming is resulting in an increase in temperatures which is set to become more marked by the end of the century and depends on the accelerating pace of greenhouse gas emissions into the atmosphere. Yet even in this scenario, so-called "cold waves" will continue to be generated and have an impact on health.

OBJECTIVES

This study sought to analyse the impact of cold waves on daily mortality at a provincial level in Spain over the 2021-2050 and 2051-2100 time horizons under RCP4.5 and RCP 8.5 emission scenarios, on the basis of two hypotheses: (1) that the cold-wave definition temperature (T _threshold) would not vary over time; and, (2) that there would be a variation in T _threshold.

MATERIAL AND METHODS

The results of a retrospective study undertaken for Spain as a whole across the period 2000-2009 enabled us to ascertain the cold-wave definition temperature at a provincial level and its impact on health, measured by reference to population attributable risk (PAR). The minimum daily temperatures projected for each provincial capital considering the above time horizons and emission scenarios were provided by the State Meteorological Agency. On the basis of the T _threshold definition values and minimum daily temperatures projected for each province, we calculated the expected impact of low temperatures on mortality under the above two hypotheses. Keeping the PAR values constant, it was assumed that the mortality rate would vary in accordance with the available data.

RESULTS

If T _threshold remained constant over the above time horizons under both emission scenarios, there would be no cold-related mortality. If T _threshold were assumed to vary over time, however, then cold-related mortality would not disappear: it would instead remain practically constant over time and give rise to an estimated overall figure of around 250 deaths per year, equivalent to close on a quarter of Spain's current annual cold-related mortality and entailing a cost of approximately €1000 million per year.

CONCLUSION

Given that cold waves are not going to disappear and that their impact on mortality is far from negligible and is likely to remain so, public health prevention measures must be implemented to minimise these effects as far as possible.

Mortality attributable to high temperatures over the 2021-2050 and 2051-2100 time horizons in Spain: Adaptation and economic estimate

BACKGROUND

In recent years, a number of studies have been conducted with the aim of analysing the impact that high temperatures will have on mortality over different time horizons under different climate scenarios. Very few of these studies take into account the fact that the threshold temperature used to define a heat wave will vary over time, and there are practically none which calculate this threshold temperature for each geographical area on the assumption that there will be variations at a country level.

OBJECTIVE

To analyse the impact that high temperatures will have on mortality across the periods 2021-2050 and 2051-2100 under a high-emission climate scenario (RCP8.5), in a case: (a) where adaptation processes are not taken into account; and (b) where complete adaptation processes are taken into account.

MATERIAL AND METHODS

Based on heat-wave definition temperature (T_threshold) values previously calculated for the reference period, 2000-2009, for each Spanish provincial capital, and their impact on daily mortality as measured by population attributable risk (PAR), the impact of high temperatures on mortality will be calculated for the above-mentioned future periods. Two hypotheses will be considered, namely: (a) that T_threshold does not vary over time (scenario without adaptation to heat); and, (b) that T_threshold does vary over time, with the percentile to which said T_threshold corresponds being assumed to remain constant (complete adaptation to heat). The temperature data were sourced from projections generated by Coupled Model Intercomparison Project (CMIP5) climate models adapted to each region's local characteristics by the State Meteorological Agency (Agencia Estatal de Meteorología/AEMET). Population-growth projections were obtained from the National Statistics Institute (Instituto Nacional de Estadística/INE). In addition, an economic estimate of the resulting impact will be drawn up.

RESULTS

The mean value of maximum daily temperatures will rise, in relation to those of the reference period (2000-2009), by 1.6⁰C across the period 2021-2050 and by 3.3⁰C across the period 2051-2100. In a case where there is no heat-adaptation process, overall annual mortality attributable to high temperatures in Spain would amount to 1414 deaths/year (95% CI: 1089-1771) in the period 2021-2050, rising to 12,896 deaths/year (95% CI: 9852-15,976) in the period 2051-2100. In a case where there is a heat-adaptation process, annual mortality would be 651 deaths/year (95% CI: 500-807) in the period 2021-2050, and 931 deaths per year (95% CI: 770-1081) in the period 2051-2100. These results display a high degree of heterogeneity. The savings between a situation that does envisage and one that does not envisage an adaptive process is €49,100 million/year over the 2051-2100 time horizon.

CONCLUSION

A non-linear increase in maximum daily temperatures was observed, which varies widely from some regions to others, with an increase in mean values for Spain as a whole that is not linear over time. The high degree of heterogeneity found in heat-related mortality by region and the great differences observed on considering an adaptive versus a non-adaptive process render it necessary for adaptation plans to be implemented at a regional level.

Does the Use of a "Walking Bleaching" Technique Increase Bone Resorption Markers?

OBJECTIVE

This randomized clinical trial evaluated the effect of 35% hydrogen peroxide in comparison with 37% carbamide peroxide in a nonvital bleaching technique of "walking bleaching" (four sessions of treatment) on periodontal markers: nuclear factor kappa B-ligand (RANK-L-process of root resorption marker) and interleukin 1β (IL-1β-inflammatory response marker).

METHODS AND MATERIALS

Fifty volunteers presenting with discoloration of nonvital teeth and endodontic treatment in good condition participated. Fifty teeth were randomly divided into two study groups according to bleaching gel: HP = 35% hydrogen peroxide (n=25) and 37% carbamide peroxide (n=25). Nonvital bleaching was performed with a walking bleaching technique consisting of four sessions of bleach application. Gingival crevicular fluid samples were taken in order to quantify the RANK-L and IL-1β levels by enzyme-linked immunosorbent assay. Samples were obtained from six periodontal sites for each bleached tooth: three vestibular and three palatine (mesial, middle, and distal) at seven time periods: baseline, after each of the four sessions of nonvital bleaching, at one week, and at one month after nonvital bleaching. Tooth color variations were analyzed in each session by VITA Bleachedguide 3D-MASTER (ΔSGU).

RESULTS

Significant increments in the RANK-L and IL-1β levels were detected in each evaluated time compared with baseline ( p<0.05); however, no differences were detected between hydrogen peroxide and carbamide peroxide on increments of the biomarkers studied. The change of color was effective for both nonvital bleaching therapies ( p<0.05).

CONCLUSIONS

Nonvital bleaching induced a significant increment in the RANK-L and IL-1β levels in periodontal tissues around bleached, nonvital teeth.

Core signalling motif displaying multistability through multi-state enzymes

Bistability, and more generally multistability, is a key system dynamics feature enabling decision-making and memory in cells. Deciphering the molecular determinants of multistability is thus crucial for a better understanding of cellular pathways and their (re)engineering in synthetic biology. Here, we show that a key motif found predominantly in eukaryotic signalling systems, namely a futile signalling cycle, can display bistability when featuring a two-state kinase. We provide necessary and sufficient mathematical conditions on the kinetic parameters of this motif that guarantee the existence of multiple steady states. These conditions foster the intuition that bistability arises as a consequence of competition between the two states of the kinase. Extending from this result, we find that increasing the number of kinase states linearly translates into an increase in the number of steady states in the system. These findings reveal, to our knowledge, a new mechanism for the generation of bistability and multistability in cellular signalling systems. Further the futile cycle featuring a two-state kinase is among the smallest bistable signalling motifs. We show that multi-state kinases and the described competition-based motif are part of several natural signalling systems and thereby could enable them to implement complex information processing through multistability. These results indicate that multi-state kinases in signalling systems are readily exploited by natural evolution and could equally be used by synthetic approaches for the generation of multistable information processing systems at the cellular level.

Assessing the role of host traits as drivers of the abundance of long-lived parasites in fish-stock assessment studies

In order to identify the best tools for stock assessment studies using fish parasites as biological indicators, different host traits (size, mass and age and their interaction with sex) were evaluated as descriptors of cumulative patterns of both parasite abundance and infracommunity species richness. The effect of such variables was analysed for a sample of 265 specimens of Percophis brasiliensis caught in the Argentine Sea. The abundances and species richness were modelled using generalized linear mixed models (GLMMs) with negative binomial and Poisson distribution respectively. Due to collinearity, separate models were fitted for each of the three main explanatory variables (length, mass and age) to identify the optimal set of factors determining the parasite burdens. Optimal GLMMs were selected on the basis of the lowest Akaike information criteria, residual information and simulation studies based on 10 000 iterations. Results indicated that the covariates length and sex consistently appeared in the most parsimonious models suggesting that fish length seems to be a slightly better predictor than age or mass. The biological causes of these patterns are discussed. It is recommended to use fish length as a measure of growth and to restrict comparisons with fish of similar length or to incorporate length as covariate when comparing parasite burdens. Host sex should be also taken into account for those species sexually dimorphic in terms of morphology, behaviour or growth rates.

Graphical reduction of reaction networks by linear elimination of species

The quasi-steady state approximation and time-scale separation are commonly applied methods to simplify models of biochemical reaction networks based on ordinary differential equations (ODEs). The concentrations of the "fast" species are assumed effectively to be at steady state with respect to the "slow" species. Under this assumption the steady state equations can be used to eliminate the "fast" variables and a new ODE system with only the slow species can be obtained. We interpret a reduced system obtained by time-scale separation as the ODE system arising from a unique reaction network, by identification of a set of reactions and the corresponding rate functions. The procedure is graphically based and can easily be worked out by hand for small networks. For larger networks, we provide a pseudo-algorithm. We study properties of the reduced network, its kinetics and conservation laws, and show that the kinetics of the reduced network fulfil realistic assumptions, provided the original network does. We illustrate our results using biological examples such as substrate mechanisms, post-translational modification systems and networks with intermediates (transient) steps.

[Preoperative use of intravenous iron: a new transfusional therapy]

INTRODUCTION AND OBJECTIVE

Improving preoperative hemoglobin levels reduces transfusion requirements. The availability in Spain of iron sucrose formulas with good safety profiles has added a new therapeutic option for treating anemia. The aim of this study was to demonstrate the usefulness of preoperative intravenous infusion of iron for improving hemoglobin level before elective major orthopedic surgery.

PATIENTS AND METHODS

From the beginning of 2003 until July 2004, 27 consecutive patients scheduled to undergo major orthopedic surgery were given preoperative intravenous iron infusions because of intolerance to oral iron administration, poor intestinal absorption, chronic inflammatory anemia, or functional iron deficit. Twenty patients received preoperative intravenous epoetin alfa and iron and 7 received only intravenous iron because epoetin alfa therapy was ruled out due to cardiovascular or thromboembolic disease or because they had pure iron deficiency. Variables studied were age, sex, weight, type of surgery, iron dose, duration of treatment, reason for treatment, blood parameters, hemoglobin levels, and use of transfusions.

RESULTS

The preoperative increase in hemoglobin was 1.7 g dL(-1) (range, 10.8-12.5) for patients who received only intravenous iron therapy and half of them were transfused, although inappropriately in 1 case. The increase in the intravenous epoetin alfa plus iron group was 1.7 g dL(-1) (range, 10.9-12.6) and only 25% were transfused.

CONCLUSIONS

Intravenous iron therapy improved the preoperative hemoglobin levels in anemic patients scheduled for major orthopedic surgery. This is a new intravenous treatment approach to evaluate.

New extraction method for the analysis of linear alkylbenzene sulfonates in marine organisms

A new method has been developed for the determination of linear alkylbenzene sulfonates (LAS) from various marine organisms, and compared with Soxhlet extraction. The technique applied includes the use of pressurized liquid extraction (PLE) for the extraction stage, preconcentration of the samples, purification by solid-phase extraction (SPE) and analysis by liquid chromatography with fluorescence detection. The spiked concentrations were added to the samples (wet mass of the organisms: Solea senegalensis and Ruditapes semidecussatus), which were homogenized and agitated continuously for 25 h. The samples were extracted by pressurized hot solvent extraction using two different extraction temperatures (100 and 150 degrees C) and by traditional Soxhlet extraction. The best recoveries were obtained employing pressurized hot solvent extraction at 100 degrees C and varied in the range from 66.1 to 101.3% with a standard deviation of between 2 and 13. Detection limit was between 5 and 15 microg kg(-1) wet mass using HPLC-fluorescence detection. The analytical method developed in this paper has been applied for LAS determination in samples from a Flow-through exposure system with the objective of measuring the bioconcentration of this surfactant.

[Factors conditioning primary care services utilization. Empirical evidence and methodological inconsistencies]

INTRODUCTION

In Spain, the degree and characteristics of primary care services utilization have been the subject of analysis since at least the 1980s. One of the main reasons for this interest is to assess the extent to which utilization matches primary care needs. In fact, the provision of an adequate health service for those who most need it is a generally accepted priority.

FACTORS CONDITIONING USE

The evidence shows that individual characteristics, mainly health status, are the factors most closely related to primary care utilization. Other personal characteristics, such as gender and age, could act as modulators of health care need. Some family and/or cultural variables, as well as factors related to the health care professional and institutions, could explain some of the observed variability in primary care services utilization. Socioeconomic variables, such as income, reveal a paradox. From an aggregate perspective, income is the main determinant of utilization as well as of health care expenditure. When data are analyzed for individuals, however, income is not related to primary health utilization.

METHODOLOGICAL INCONSISTENCIES

The situation is controversial, with methodological implications and, above all, consequences for the assessment of the efficiency in primary care utilization. Review of the literature reveals certain methodological inconsistencies that could at least partly explain the disparity of the empirical results. Among others, the following flaws can be highlighted: design problems, measurement errors, misspecification, and misleading statistical methods.Some solutions, among others, are quasi-experiments, the use of large administrative databases and of primary data sources (design problems); differentiation between types of utilization and between units of analysis other than consultations, and correction of measurement errors in the explanatory variables (measurement errors); consideration of relevant explanatory variables (misspecification); and the use of multilevel models (statistical methods).

Safety of long-term treatment with cyclosporin A in resistant chronic plaque psoriasis: a retrospective case series

BACKGROUND

An intermittent short course of cyclosporin A (CyA) therapy is a good choice in the treatment of severe psoriasis. Nevertheless, some severe or resistant patients might benefit from long-term treatment. Adverse effects of long-term use of CyA are investigated and the results are compared with the literature.

PATIENTS AND METHODS

A retrospective study of adverse effects of CyA treatment in a group of 53 patients suffering from psoriasis. The mean treatment time was 31.4 +/- 23.2 months with a minimum of 4 months to a maximum of 95 months, with very few short interruptions of treatment (from 2 to 5 months in five patients).

RESULTS

The group consisted of 29 women and 24 men, ranging in age from 18 to 65 years, with an average age of 44.49 years. Arterial hypertension appeared in 45.3% of patients during treatment. Pharmacological treatment was required in 32% of these patients to control the condition. Serum creatinine levels were transiently elevated in 11.3% of the cases, but withdrawal of treatment was required in none of them.

DISCUSSION

Long-term CyA treatment might be necessary in some patients and this study shows that it could be sustained with a close follow-up. This involves regular visits depending on each patient, as well as common test protocol and clinical evaluation. In conclusion, this retrospective study seems to confirm the relative safety of long-term CyA treatment when patients are adequately monitored.

[Erythropoietin alone or as an adjuvant for the autologous blood donation program in major orthopedic surgery]

BACKGROUND

Patients with anemia undergoing elective joint replacement are often excluded from preoperative autologous donation (PAD). The purpose of this study was to compare the efficacy of preoperative erythropoietin (epoetin alpha) as an adjuvant treatment to PAD versus preoperative erythropoietin alfa alone in patients with mild anemia undergoing major orthopedic surgery.

PATIENTS AND METHODS

The study enrolled 75 patients scheduled for total joint arthropalsty of the hip or knee or spinal surgery and with a hemoglobin (Hb) concentration between 10 and 13 g/dL. Group 1 patients were assigned to receive weekly doses of subcutaneous epoetin alpha (40,000 IU) 21, 14, and 7 days before surgery and to participate in the PAD program; group 2 patients were excluded from the PAD program and received 2 doses of epoetin alpha every week over the same period.

RESULTS

Group 1 (n = 39) and group 2 (n = 36) were similar with respect to patient characteristics, biological parameters, and surgical procedures, In group 1, mean preoperative Hb rose fom 12.5 g/dL to 12.8 g/dL, patients received a mean 5.1 doses of epoetin alpha, and they gave a mean 1.9 units of autologus blood and 1 received allogenic blood. In group 30.7% received transfusions of autologous blood and 1 received allogenic blood. In group 2, preoperative Hb increased from 11.7 g/dL to 13.5 g/dL, patients received 3.8 doses of epoetin alpha, and 3 were transfused with allogenic blood (P > 0.05).

CONCLUSION

Epoetin alpha alone and erythropoietin as a adjuvant to a PAD program are equally effective in reducing allogenic transfusion during hip and knee arthroplasty and spinal column surgery of up to 3 spaces.

[Comparison of two methods in the analysis of the short-term effect of air pollution on health]

OBJECTIVE

We compare two methods to analyse the relationship between air pollution and health. One of them (ME) is based on a generalized linear model, while the other one (MN) incorporates a generalized additive model (GAM). Besides the statistical model used, both methods schow additional discrepancies for the type and number of variables used in the control of confounding.

METHOD

An analysis was carried out for each lag of black smoke (0 to 5) and several health indicators from the city of Valencia (Spain) following both methods. Results were compared examining the sequence and the lag of the higher coefficient. The ratio between confidence intervals width and the percent difference in the estimates were also obtained.

RESULTS

The discrepancies in results according to the methodology were small. The sequence shaped and the lag of higher coefficient generally remained invariant. Coefficients were similar (percent difference of MN over ME was not greater than 10%). Confidence intervals were more precise for MN, although the reduction was not very strong (the width ratio was around 90%).

CONCLUSIONS

The short variation of the results guarantees the applicability of both MN and ME methods, although the systematic reduction of the standard error of MN supports its use as a more efficient procedure to control for confounding.

[Ponderal evolution in the Girona population, 1989-1999]

BACKGROUND AND OBJECTIVE

Despite the number of plans leading to lose weight among individuals in the developed countries, the prevalence of obesity has increased since 1980. The knowledge of ponderal evolution in a given population is very important because the adverse effects of obesity vary greatly among individuals and populations. The objective of the present paper was to determine the modifications in the different degrees of body adiposity in a population in Catalunya.

PATIENTS AND METHODS

A measurement was made of weight and height of 24554 users aged over 14 years (10595 males and 13959 females) attended at four basic health areas (BHA): Girona 1, Girona 4, Salt and Camprodon, and a Primary Health Center (PHC) in the Girona province, for a five-year period, 1995-1999. The prevalence of the different degrees of obesity was compared with that obtained in a previous study with 6373 individuals during the 1986-1989 period (4,579 males and 1794 females).

RESULTS

The prevalence of women with overweight (defined as a body mass index [BMI] > 25 kg/m2) increased from 7.3% (1986-1989, study 0) to 17.6% (1995-1999, study 1) for women aged 15 to 24 years ( p < 0.001), from 17.9 % to 28.1% for women aged 25 to 34 years (p < 0.001), and from 37.5% to 44.7 % for women aged 35 to 44 years (p < 0.001). In the latter age group, the proportion of women with obesity (BMI > 30 kg/m2) increased from 6.9% to 12.9%. Similar trends were observed among men, and the change in the 35-44 year age group (from 10.5 % of obese men to 16% [p < 0.001]), and 55 to 65 years (from 16.6% of obese men to 22.7% [p < 0.001] was particularly significant. And lastly, it is also noteworthy the proportion of individuals with low weight (BMI < 18.5 kg/m2) which increased from 7.3% to 11.6% for women aged 15 to 24 years, and from 0.3% to 2.2% for women aged 35 to 44 years. This trend was also observed for men aged 15 to 24 years (11% to 17.2%).

CONCLUSIONS

The relative increase in the prevalence of overweight and obesity runs in parallel to that found in other surrounding countries. Also, it is worth mentioning that among women aged 15 to 24 years the increase in the prevalence of low weight and obesity is almost identical, which invalidates the mean and median values as a means to assess the ponderal evolution in this population. The current compartmentalization between the extreme BMIs, particularly among the youngest portion of population should be addressed from a multidisciplinary perspective.

The EMECAM project: a multicentre study on air pollution and mortality in Spain: combined results for particulates and for sulfur dioxide

OBJECTIVE

The EMECAM study is a collaborative effort to evaluate the impact of air pollution on mortality in Spain. In this paper the combined results are presented for the short term effects of particulates and sulfur dioxide on both daily mortality for all and for specific causes.

METHODS

The relation between daily mortality for all causes, cardiovascular diseases, and respiratory diseases, and air pollution for particulates (daily concentrations) and SO(2) (24 and 1 hour concentrations) was assessed in 13 Spanish cities for the period 1990-6. With a standardised method, magnitude of association in each city was estimated by Poisson regression in a generalised additive model. Local estimates were obtained from both single and two pollutant analyses. Lastly, combined estimates for each cause and pollutant were obtained.

RESULTS

For combined results, in single pollutant models a 10 microg/m(3) increase in the concentration of the mean of the concurrent and one day lag for black smoke was associated with a 0.8% (95% confidence interval (95% CI) 0.4 to 1.1%) increase in total mortality. The estimates for total suspended particles (TSPs) and particulate matter of aerodynamic diameter <10 microm (PM(10)) and total mortality were slightly lower. The same increase in concentrations of SO(2) was associated with a 0.5% increase in daily deaths. For groups of specific causes, higher estimations were found, specially for respiratory conditions. Peak concentrations of SO(2) showed significant associations with the three groups of mortality. When two pollutant analyses were performed, estimates for particulates, specially for black smoke, did not substantially change. The estimates for daily concentrations of SO(2) were greatly reduced, but, on the contrary, the association with peak concentrations of SO(2) did not show any change.

CONCLUSIONS

There is an association between mortality and pollution through particulates among city populations in Spain. Peak rather than daily concentrations of SO(2) were related to mortality. Results suggest that populations in Spanish cities are exposed to health risks derived from air pollution.

Occurrence and distribution of linear alkylbenzene sulfonates and sulfophenylcarboxylic acids in several Iberian littoral ecosystems

The distribution of linear alkylbenzene sulfonates (LAS) and sulfophenylcarboxylic acids (SPC) has been characterized in water and sediment of five Iberian estuaries and a saltmarsh channel. The highest concentrations of LAS and SPC were detected in shallow zones close to discharge points of untreated urban effluent, and decreased sharply with increasing distance from these. SPC homologues of between 3 and 12 carbon atoms were detected, although their concentrations were several orders of magnitude lower than the corresponding LAS. The highest SPC concentrations found were of medium carboxylic chain lengths (C6-C8) in water, and of longer chain lengths (C9-C11) in particulate material. LAS homologues were associated preferentially with the particulate material. The vertical distribution of LAS in the water column was not homogeneous, in contrast to that presented by the SPC homologues. In the case of the Sancti Petri Channel, there was a net flow of LAS exportation into the Bay of Cádiz, of -38.6 kg day(-1), and a net flow for SPC of -6.0 kg day(-1). The daily mass input of LAS and their biodegradation intermediates from the Sancti Petri Channel to Cadiz Bay was 44.6 kg.

Bioconcentration of linear alkylbenzene sulfonates and their degradation intermediates in marine algae

Sorption experiments using different homologues of linear alkylbenzene sulfonate (LAS) and sulfophenylcarboxylic acid (SPC) on several marine microalgae have been carried out. The steady state seems to be reached in the first 4 hours. Longer exposure times lead to biodegradation of the compound and, therefore, to an overestimation of the bioconcentration factor. Sorption coefficients are higher for Nannochloropsis gaditana, for example, 1,293 Lkg(-1) for C11-LAS and 525 Lkg(-1) for C11-SPC versus 727 Lkg(-1) for C11-LAS and 28 Lkg(-1) for C11-SPC for Dunaliella salina. For both algae an increase in the sorption coefficient is observed when the polarity of the compound decreases (C5-SPC<C11-SPC<C11-LAS approximately/= C12-LAS). The sorption of C11-LAS on D. salina is fitted to a linear Freundlich isotherm (K=176+/-0.02, n=0.964+/-0.02).

[The problem of repeated measurements. Longitudinal analysis in epidemiology]

In longitudinal analyses subjects are repeatedly measured along time. They are mixed designs, characterised for their simultaneous consideration of two or more dimensions of analysis, in which time is one of the dimensions.Longitudinal analyses have important advantages with respect other designs. The most important is that they are more efficient, since they allow to distinguish between-individual and within-individual variation.Longitudinal analyses can be approached marginal and conditionally. Whereas the former allows to draw poblational, or average, inferences, the latter permits to draw individual inferences.The statistical models to use depend on the type of response variable. If the dependent variable is normally distributed one will use linear mixed models. When the response is a count one will use mixed Poisson regressions. Mixed binomial or multinomial logistic regressions should be used when the response would be categorical.

Material deprivation and leading causes of death by gender: evidence from a nationwide small area study

STUDY OBJECTIVE

To investigate the association between material deprivation and 10 leading causes of death by gender.

DESIGN

Small area cross sectional ecological study using two dimensions of material deprivation (Index 1 and Index 2) drawn from 1991 census and cause specific mortality data aggregated for 1987-1995.

SETTING

2218 small areas in Spain.

MAIN RESULTS

Strong detrimental associations of two deprivation indices were found with top six leading causes of death for men and top seven leading causes of death for women, except breast cancer. For men, the highest percentages of excess mortality (between 40% and 60%) were found for smoking and alcohol related causes of death such as lung cancer, chronic obstructive pulmonary diseases, and cirrhosis while for women the highest percentages of excess mortality (between 40% and 60%) were found for diet related causes such as diabetes and ischaemic heart disease.

CONCLUSIONS

Health inequality is a widespread phenomenon in the majority of the top leading causes of deaths of the nation. Increasing levels of deprivation indices are associated with mortality risk differently by both cause and gender. Results suggest that deprivation effects mainly captured by Index 2 may manifest largely as unfavourable health behaviours leading to gender specific sets of causes of deaths. Findings of this study are consistent with the idea that material deprivation determines health inequality through both an increase of general susceptibility to ill health, leading to excess mortality in a wide range of causes, and a set of specific factors, resulting in an increased risk of death from a specific set of causes in each gender.

[Prevalence of obesity in the population assisted at primary health care services in Girona, 1995-1999]

OBJECTIVES

To estimate the prevalence of obesity and overweight in the population of Girona (Spain) between 1995 and 1999 and to divide the prevalences in geographical areas according to age and sex.

METHODS

Height and weight were directly measures in 24,554 health care consumers older than 14 years (10,595 men and 13,959 women) treated in four primary health care areas: Girona 1, Girona 4, Salt and Camprodon and in one primary health care center in the province of Girona. Body mas index (BMI) was calcuted by dividing weight in kilograms bye height in meters squared. Obesity was defined as grades II and III of Garrow's index (BMI >= 30 kg/m2) and overweight as degree I (25 kg/m2 >= BMI < 30 kg/m2). Because the sample was not randomized, the prevalences were adequately weighted. The comparison between prevalences in two different primary health care areas for each sex (in the same Garrow's index and age group) was carried out using a parametric test of differences in proportions (Student's t-test). A hierarchical logistic regression was used to compare prevalences in the same grade Garrow's index, controlling for age and sex.

RESULTS

The prevalence of obesity was estimated as 15.6% in men aged from 20-74 years (from 14.0% in Girona 1 to 22.4% in Camprodon) and 17.5% for women (15.6% in Girona 1, 22.7% in Camprodon). The weighted mean was 16.7%. The prevalence of overweight was 44% in men and 33% in women and the weighted mean was 37.8%. The prevalence of obesity was graduated with statistically significant differences between Girona 1, Salt, Girona 4, Camprodon and Sils.

CONCLUSIONS

The estimates of the prevalences of obesity and overweight obtained in this study were closer to those of other studies in similar populations than previously believed. Indeed, the prevalences may be similar to those of the European Union and, in some age groups, to those of the United States.

Extraction and isolation of linear alkylbenzene sulfonates and their intermediate metabolites from various marine organisms

A method has been developed for the determination of linear alkylbenzene sulfonates and its degradation intermediates (sulfophenylcarboxylic acids) from different marine organisms, which includes the stages of extraction and analysis by liquid chromatography with fluorescence detection. The extraction stage (Soxhlet and solid-phase extractions) was optimised by the selection of the appropriate solvent, minicolumns and different clean-up stages. Recoveries varied in the range from 80 to 104%, with a standard deviation between 1 and 9%. Detection limits were 15 ng g(-1) wet mass for undecylbezene sulfonate and 30 ng g(-1) wet mass for sulfophenylundecanoic acid using HPLC-fluorescence detection. The complete analytical method was successfully applied to different marine organisms from the Bay of Cadiz (SW Spain).

Cutaneous primary paracoccidioidomycosis

Paracoccidioidomycosis is a common fungal infection in Latin America. Few cases have been described in non-endemic countries and their diagnosis without the correct suspicion, bearing in mind that the latency period might be up to 60 years, may not be easy. We report the case of a 59-year-old man who worked as a taxi driver for 25 years in Venezuela. Cutaneous paracoccidioidomycosis was diagnosed one year after he returned to Spain. No internal signs or symptoms of the disease were found and cell-mediated immunity showed no depression. Our case suggested us to consider direct cutaneous infection, although respiratory tract is believed to be the most frequent portal of entry for this infection.

Modelling asthma epidemics on the relationship between air pollution and asthma emergency visits in Barcelona, Spain

We have investigated different methods of controlling for asthma epidemics in the time series regression of the relationship between air pollution and asthma emergency visits in Barcelona, Spain. The relationship between air pollution and asthma emergency room visits was modelled using autoregressive Poisson models. We examined the effect of using no control by epidemics, and modelling asthma epidemics with a single dummy variable, six dummy variables, and a dummy variable for each epidemic day. Air pollution coefficients increased when controlling asthma epidemics with six dummy variables instead of a single variable. They further increased when autocorrelation was allowed for. Standard errors were relatively unaffected when either the epidemics or the autocorrelation were included in the model. Black smoke, nitrogen dioxide and ozone were statistically significant associated to asthma emergency visits after using six dummy variables to control for asthma epidemics. We have shown that different models, including different confounding variables, give markedly different estimates of the effect of a pollutant on health. Care is needed in the interpretation of such models, and careful reporting so it is clear how the confounding variables have been modelled.

[A comparative study of the evolution of caries in mentally retarded subjects of 5 years' duration]

OBJECTIVE

To study the evolution of caries in two groups of mentally retarded individuals.

DESIGN

Longitudinal, prospective, non randomized study, with a five-years follow-up period, with intervention and control groups.

SETTING

Community trial. Primary health care centre in Martorell.

SUBJECTS

Mentally retarded individuals attending a workshop school (intervention group, N = 29) and living in a boarding school (control group, N = 25).

INTERVENTION

One group was on a program of prevention and treatment of caries, the other one received the usual care and acted as a control group.

MEASUREMENT AND MAIN RESULTS

The number of absent, filled and caries teeth were studied from 1992-1997. An analysis of the variance with repeated measures was carried out. The groups were comparable for most demographic characteristics and basal odontological parameters. While in the control group the number of caries increased (mean92 = 2.2; standard error [SE] = 0.5); mean97 = 3.3; SE = 0.5; p = 0.03) in the intervention group it did not change (mean92 = 1.8: SE = 0.4; mean97 = 1.7; SE = 0.2; p = 0.73). The variation over time was significantly different between the groups (p = 0.03). The mean of filled teeth increased in the intervention group (mean92 = 0.7; SE = 0.4; mean97 = 2.2; SE = 0.4; p < 0.0001) and it did not change in the control group (mean92 = 1.2; SE = 0.5; mean97 = 1.4; SE = 0.6; p = 0.48). There were statistical significant differences between the two groups in the variation over time (p = 0.017).

CONCLUSIONS

Preventive and curative odontological intervention in mentally retarded individuals can be useful to improve the evolution of caries.

[Temporary disability: analysis strategies]

OBJECTIVES

To apply different regression models to estimate rate ratios for temporary sick-leave (TSL) which may occur several times in the same individual during a period, and the frequency is not constant for the observation period.

SUBJECTS AND METHODS

All workers employed more than 30 days between January 1st of 1992 and June 1st of 1995 were included into the population study. The following period was 1,259 days and the total number of workers included in the study was 2,306. During that period 2,649 TSL episodes were notified, which meant 85,947 lost days. Poisson regression, Generalised Estimating Equations (GEE) and Andersen-Gill modification of Cox regression modify by Wei (WLW) were applied.

RESULTS

The highest TSL incidence rates were seen in women, lesser than 30 years old, cleaners, maintenance workers and auxiliary nurses, and those involved in shiftwork. This profile was not modified after applying GEE and WLW regression models, although confidence intervals were widened.

CONCLUSIONS

TSL data does not fit Poisson regression assumptions, but GEE and WLW regression models do not appear as alternatives. Other conditional regression models would need to be explored to suitably analyse this data.

[The short-term effects of air pollution on mortality. The results of the EMECAM project in the city of Barcelona, 1991-1995. Estudio Multicéntrico Español sobre la Relación entre la Contaminación Atmosférica y la Mortalidad]

BACKGROUND

Most of the studies which demonstrate the existence of a short-term relationship between air pollution and morbidity and the Mortality analyze the impact of "classic" pollutants which are by-products of combustion. However, the changes in the sources of these emissions, shifting basically toward road traffic, has made a change in air pollution, heightening the importance of the photochemical components, such as ozone (O3) and nitrogen dioxide (NO2). Barcelona is a city located in a mild climate zone, and its air pollution comes mainly from vehicle emissions. The main objective of this article is that of analyzing the relationship between the photochemical pollutants, NO2 and O3 and the death rate for different causes in the city of Barcelona throughout the 1991-1995 period, using the procedure for analysis set out as part of the EMECAM Project.

METHODS

Daily changes in the number of deaths resulting from all causes, of the number of deaths for all causes of those over age 70, of the number of deaths resulting from cardiovascular diseases, and of the number of deaths resulting from respiratory-related causes are related to the daily changes in the photochemical pollutants using autoregressive Poisson models, controlling confusion-causing variables such as the temperature, the relative humidity, the systematic time structure and the autoregressive structure.

RESULTS

Except for the relationship between O3 and the mortality for causes involving respiratory diseases, the relationships between photochemical pollutants and the mortality for all the causes considered were statistically significant. The risks related to dying as a result of rises in O3 were greater than as a result of rises in NO2, almost triple among cardiovascular diseases. The risks related to dying for all the causes are lower than for specific causes and than for those individuals over age 70. The results of the analysis by six-month periods are quite similar to the overall results, revealing, in any event, relative risks somewhat greater during the warm months (May to October).

CONCLUSIONS

Photochemical pollution, especially that which is caused by O3, comprises a health risk. In the case of NO2, this might not be more than an indicators of the suspended particles or of other pollutants stemming from city traffic. There may be a certain adjustment between six-month periods of the impact of O3 on the mortality for causes of the circulatory system.