Life-course socio-economic status and its impact on functional health of Portuguese older adults

Functional health is arguably one of the most important health indicators for older adults, because it assesses physical, cognitive and social functions in combination. However, life-course circumstances may impact this multidimensional construct. The aim of the present study was to assess the relationship between life-course socio-economic status (SES) and different dimensions of functional health in older adults. Data on 821 Portuguese adults aged 50 years and over in 2013-2015 were analysed. Life-course SES was computed using participants' paternal occupation (non-manual (nm); manual (m)) and own occupation (nm; m), resulting in four patterns: stable high (nm + nm), upward (m + nm), downward (nm + m) and stable low (m + m). Functional health included physical and mental functioning, cognitive function, handgrip strength, and walking speed. Linear (beta coefficients) and logistic regressions (odds ratios) were used to estimate the association between life-course SES and functional health.Overall, those who accumulated social disadvantage during life-course presented worse functional health than those with stable high SES (stable low - SF-36 physical functioning: β = -9.75; 95% CI: -14.34; -5.15; SF-36 mental health: β = -7.33; 95% CI: -11.55; -3.11; handgrip strength: β = -1.60; 95% CI: -2.86; -0.35; walking time, highest tertile: OR = 5.28; 95% CI: 3.07; 9.09). Those with an upward SES were not statistically different from those in the stable high SES for most of the health outcomes; however, those with an upward SES trajectory tended to have higher odds of cognitive impairment (OR = 1.75; 95% CI: 0.96; 3.19). A downward SES trajectory increased the odds of slower walking speed (OR = 4.62; 95% CI: 1.78; 11.95). A disadvantaged life-course SES impacts older adults' physical and mental functioning. For some outcomes, this was attenuated by a favourable adulthood SES but those with a stable low SES consistently presented worse functional health.

Childhood social adversity and clustering of health risk behaviours during early adolescence in a population-based birth cohort

OBJECTIVES

This study aimed to prospectively explore the association between early lifetime exposure to psychosocial adversity and engagement in health risk behaviours (HRBs) during early adolescence.

STUDY DESIGN

This was a prospective study.

METHODS

This study used data from the baseline (2005-2006), third (2016-2017) and fourth waves (2018-2020) of the Generation XXI birth cohort. Socio-economic circumstances (SECs) at baseline, adverse childhood experiences (ACEs; e.g. abuse, neglect, household dysfunction) at age 10 years and HRBs (i.e. alcohol consumption, smoking, physical exercise level, sedentary behaviours, sleep duration and eating behaviours) at age 13 years were measured. Patterns of HRBs were obtained using latent class analysis. Latent class regression analysis was used to estimate the likelihood of being engaged in HRBs according to the extent of exposure to ACEs (i.e. 0 ACEs, 1-3 ACEs, 4-5 ACEs and ≥6 ACEs) and negative family SECs.

RESULTS

Adolescents whose mothers had a low level of education (adjusted odds ratio [aOR] = 2.72 [95% confidence interval {CI}, 2.33-3.18]), low occupational status (aOR = 3.21 [95% CI, 2.68-3.85]) and low income (aOR = 2.70 [95% CI, 2.23-3.28]) were more likely to be engaged in HRBs than their peers with higher SECs. Adolescents who experienced more ACEs were at a significantly increased risk of involvement in HRBs (aOR = 1.86 [95% CI, 1.33-2.63] for 4-5 ACEs vs aOR 2.41 [95% CI, 1.72-3.43] for ≥6 ACEs). No significant gender differences were observed.

CONCLUSIONS

Adolescents from families with low SECs were more likely than their more affluent counterparts to be engaged in HRBs. Furthermore, more ACEs contributed to widening health inequalities.

Abuse among Portuguese older people at a time of economic crisis recovery: findings from the Harmed study

This study aimed to assess the prevalence of abuse against Portuguese older people after an economic crisis and to assess how it has influenced health. A cross-sectional study was carried out including 677 older adults (≥60 years) during 2017. Results show that overall, 23.9% of older people reported being a victim of abuse in the last 12 months. The prevalence of psychological abuse was 19.9%, financial abuse 5.8%, physical abuse 2.5% and sexual abuse 1.9%. Older people who report abuse were more likely to have perceived insufficient income and low social support. The abuse was also significantly associated with poor health status and depressive symptoms. Even in an auspicious period, more than a fifth of older people experiences abuse which is associated with social and health vulnerabilities. These results support that an investment should be made in terms of policies toward an age-friendly environment.

Characterizing the Chemical Profile of Incidental Ultrafine Particles for Toxicity Assessment Using an Aerosol Concentrator

Incidental ultrafine particles (UFPs) constitute a key pollutant in industrial workplaces. However, characterizing their chemical properties for exposure and toxicity assessments still remains a challenge. In this work, the performance of an aerosol concentrator (Versatile Aerosol Concentration Enrichment System, VACES) was assessed to simultaneously sample UFPs on filter substrates (for chemical analysis) and as liquid suspensions (for toxicity assessment), in a high UFP concentration scenario. An industrial case study was selected where metal-containing UFPs were emitted during thermal spraying of ceramic coatings. Results evidenced the comparability of the VACES system with online monitors in terms of UFP particle mass (for concentrations up to 95 µg UFP/m3) and between filters and liquid suspensions, in terms of particle composition (for concentrations up to 1000 µg/m3). This supports the applicability of this tool for UFP collection in view of chemical and toxicological characterization for incidental UFPs. In the industrial setting evaluated, results showed that the spraying temperature was a driver of fractionation of metals between UF (<0.2 µm) and fine (0.2-2.5 µm) particles. Potentially health hazardous metals (Ni, Cr) were enriched in UFPs and depleted in the fine particle fraction. Metals vaporized at high temperatures and concentrated in the UF fraction through nucleation processes. Results evidenced the need to understand incidental particle formation mechanisms due to their direct implications on particle composition and, thus, exposure. It is advisable that personal exposure and subsequent risk assessments in occupational settings should include dedicated metrics to monitor UFPs (especially, incidental).

Socioeconomic position and quality of life among older people: The mediating role of social support

Social support can obscure social gradients in health, but its role as a mediator between socioeconomic position (SEP) and quality of life (QoL) in older populations remains unknown. We aimed to examine to what extent social support mediates the association between SEP and overall QoL among older adults (aged 60-84 years). We studied a population-based cohort of 585 noninstitutionalized adults in Porto, Portugal, who were evaluated in 2009. Education, occupation, and perceived income adequacy were used as SEP indicators. The WHOQOL-OLD was used to determine overall QoL. Social support was assessed using the Multidimensional Scale of Perceived Social Support. Path analysis was conducted to quantify direct, indirect, and total effects of SEP on QoL. There was a positive total effect of education on QoL (β = 0.28; 95% CI: 0.05-0.48). In this model, we found an indirect effect through social support (β = 0.15; 95% CI: 0.05-0.26), explaining 54% of the pathway between education and QoL. A similar pattern was identified for the association between occupation and QoL. Perceived income adequacy had a total effect of 2.74 (95% CI: 1.68-3.93) on QoL. Although an indirect effect through social support was found (β = 0.98; 95% CI: 0.42-1.55), a direct effect from this variable remained (β = 1.76; 95% CI: 0.65-2.90). Social support can be a mechanism through which SEP impacts the QoL of older people. Strengthening social support ties may attenuate the impact of social inequalities and improve the QoL of this population.

Parental socioeconomic position and chronic inflammation during adolescence

Background

Early life adversity has been associated with increased risk of inflammation and inflammation-related diseases in adulthood. This study aimed to examine the association of parental socioeconomic position with chronic inflammation over adolescence.

Methods

We used information on 2942 members (1507 girls and 1435 boys) of the EPITeen cohort that was established in 2003 in Porto, Portugal, and included 13 years old adolescents that were further evaluated at 17 and 21 years. Mother’ and father’s education and occupation were used as indicators of parental socioeconomic position. High-sensitivity C-reactive protein (CRP) was measured at three points in time (13, 17 and 21 years). CRP levels were categorized in tertiles separately for each wave; chronic inflammation in adolescence was defined as having CRP levels in the highest tertile in at least 2 waves and never in the lowest tertile.

Results

Over adolescence, the prevalence of chronic inflammation was significantly higher among participants with low parental socioeconomic position. Low parental socioeconomic position was associated with chronic inflammation in adolescence, after adjustment for sex, perinatal and physical environment factors, health-related behaviours and health status in adolescence OR = 1.63; 95%CI: 1.11, 2.40 for lowest vs. highest mother’s education and OR = 1.61; 95%CI: 1.12, 2.30 for lowest vs. highest father’s education.

Conclusions

Low parental socioeconomic position is associated with chronic inflammation during adolescence. Our results suggest that the early life socioeconomic environment has an impact on inflammatory processes over adolescence.

Early socioeconomic circumstances and adverse childhood experiences in 10-year-old children

Background

Evidence showed that adverse childhood experiences (ACEs) are associated with the development of disease later in life and premature death. Examining the occurrence of these experiences at early ages would contribute to intervene and therefore to reduce health inequalities. This study aimed to assess the prevalence of ACEs among 10-year-children and to examine its association with early socioeconomic circumstances.

Methods

At the fourth wave of the population-based birth cohort Generation XXI, from Porto, Portugal, 5153 children completed a self-report questionnaire on 9 experiences related to household dysfunction and physical and emotional abuse. Socioeconomic circumstances included household income, maternal and paternal education, and history of parental unemployment. Logistic regression was performed to calculate the Odds Ratios (OR) and 95% Confidence Intervals (95%CI).

Results

A high prevalence of physical and emotional abuse was reported by children from low socioeconomic circumstances. A graded relationship between socioeconomic circumstances and cumulative ACEs was observed, for instance, low household income was associated with increased number of ACEs (one event [OR = 1.10; 95%CI: 0.89-1.36], two events [OR = 1.41; 95%CI: 1.15-1.73], three events [OR = 1.67; 95%CI: 1.34-2.06], and four or more events [OR = 2.05; 95%CI: 1.64-2.55]). Also, living with one parent or none of them increased the likelihood of reporting multiple ACEs (OR = 5.50; 95%CI: 4.23-7.13).

Conclusions

Children from low socioeconomic circumstances were more likely to report multiple adverse experiences in the first decade of life. These findings support that children from less advantaged environments might be at a higher risk of co-occurrence of adverse experiences during their childhood.

Key messages

Prevalence of ACEs is high among 10-year-old children and is associated with low socioeconomic circumstances. Social inequalities in children should be prioritized by public health policy.

Early socioeconomic circumstances and cardiometabolic health in 10-year-old children

Background

Social adversity is thought to become biologically embedded during sensitive periods of development, setting children on a trajectory of increased risk for later chronic diseases. Thus, social differences are expected to be expressed as biological alterations and might have their origins in early life. Therefore, we aim to estimate the association between early socioeconomic position (SEP) and cardiometabolic health during childhood.

Methods

Data from 2962 participants in the population-based birth cohort Generation XXI, from Porto, Portugal, was collected following standardized procedures at all study waves. Early SEP definition included household income, parental education and occupation at child’s birth. Cardiometabolic health was characterized at the age of 7 and 10, considering the triglycerides, cholesterol, fasting glucose, body mass index, systolic and diastolic blood pressure. Logistic regression was used to estimate the association between early SEP and a favorable cardiometabolic health profile.

Results

A favorable cardiometabolic profile was observed in almost half of participants at both ages, particularly among high SEP children who remain more frequently without alterations. For girls, higher paternal education at 7 years (OR:1.49;95%CI:1.03-2.15) and higher SEP at 10 were associated with better cardiometabolic health profile. In boys, a better cardiometabolic health profile was observed with increasing levels in maternal and paternal education and occupation, but at the age of 10, social differences were more evident according to parental education.

Conclusions

We provide evidence that children from more advantaged SEP at birth have an increased likelihood of presenting better cardiometabolic health at early ages. Social differences in cardiometabolic health biomarkers are already found in childhood, suggesting that the short-term impact of early life SEP on the physiology dysregulation takes place already in the first decade of life.

Key messages

Social differences in cardiometabolic health are already established in the first decade of life, with children from higher SEP presenting a better cardiometabolic health. Cardiovascular events are not expected to develop during childhood, however the underlying atherosclerotic process might already be in course as social differences appear to widen with age.

Usinagem em CAD/CAM x Técnicas de Fabricação Pré-Sinterização

Este estudo teve por objetivo avaliar e comparar o efeito de diferentes técnicas de fabricação de espécimes de cerâmica Y-TZP pré- sinterizada (usinagem em CAD/CAM Vs técnicas de fabricação in-lab) na rugosidade superficial, transformação de fase, topografia de superfície e comportamento mecânico. Para isso, discos pré-sinterizados de cerâmica Y-TZP (IPS e.max ZirCAD, Ivoclar Vivadent) foram confeccionados segundo as normas da ISO 6872-2008 para flexão biaxial de corpos cerâmicos (piston-on-three balls - 18 mm de diâmetro x 1.5 mm de espessura) através de diferentes técnicas: Machined- usinado em CAD/CAM Polished- corte com disco diamantado seguido de polimento com lixa de carbeto de silício Xfine- corte com disco diamantado seguido pelo desgaste com ponta diamantada extra-fina Fine- corte com disco diamantado seguido pelo desgaste com ponta diamantada fina Sic- corte com disco diamantado seguido pelo desgaste com lixa de carbeto de silício. Após a confecção, os discos foram sinterizados de acordo com as recomendações do fabricante e submetidos às análises de rugosidade, resistência biaxial, limite de fadiga, transformação de fase e topografia superficial. Foi observado que o processo de fabricação influenciou as características superficiais e o comportamento mecânico interferindo nos desfechos observados. O desgaste com ponta diamantada fina demonstrou ser o melhor método para mimetizar a usinagem em CAD/CAM. Nenhum conteúdo de fase monoclínica foi observado nas diferentes técnicas de confecção avaliadas.Palavras-chave: Cerâmica. Projeto Auxiliado por Computador. Zircônia.

CAD/CAM machining Vs pre-sintering in-lab fabrication techniques of Y-TZP ceramic specimens: Effects on their mechanical fatigue behavior

This study evaluated the effects of different pre-sintering fabrication processing techniques of Y-TZP ceramic (CAD/CAM Vs. in-lab), considering surface characteristics and mechanical performance outcomes. Pre-sintered discs of Y-TZP ceramic (IPS e.max ZirCAD, Ivoclar Vivadent) were produced using different pre-sintering fabrication processing techniques: Machined- milling with a CAD/CAM system; Polished- fabrication using a cutting device followed by polishing (600 and 1200 SiC papers); Xfine- fabrication using a cutting machine followed by grinding with extra-fine diamond bur (grit size 30 μm); Fine- fabrication using a cutting machine followed by grinding with fine diamond bur (grit size 46 μm); SiC- fabrication using a cutting machine followed by grinding with 220 SiC paper. Afterwards, the discs were sintered and submitted to roughness (n=35), surface topography (n=2), phase transformation (n=2), biaxial flexural strength (n=20), and biaxial flexural fatigue strength (fatigue limit) (n=15) analyses. No monoclinic-phase content was observed in all processing techniques. It can be observed that obtaining a surface with similar characteristics to CAD/CAM milling is essential for the observation of similar mechanical performance. On this sense, grinding with fine diamond bur before sintering (Fine group) was the best mimic protocol in comparison to the CAD/CAM milling.

Are posts necessary for the restoration of root filled teeth with limited tissue loss? A structured review of laboratory and clinical studies

Guidelines for post placement are lacking in respect of the amount of tooth structure, particularly in cases in which ≥50% of coronal structure is preserved. The aim of this review was to provide evidence-based principles for the use of posts in the restoration of root filled teeth with limited tissue loss. A literature search of laboratory and clinical studies published between 2000 and 2014 was conducted in PubMed. Included studies contained at least one study group with root filled teeth restored without a post, presented at least one group with root filled teeth with limited tissue loss, and, in the case of laboratory studies, performed mechanical cycling prior to a fracture resistance test. Based on the evidence from laboratory studies, root filled premolars and molars with limited tissue loss can be restored without posts, particularly when total coverage is planned. However, when no cusp protection is provided, post placement appears to be beneficial in premolars. Evidence regarding the best restoration option for root filled incisors with limited tissue loss remains controversial. When total coverage is intended, reconstruction seems to be successfully performed by restoration with composite. However, some reports consider that post insertion increases fracture loads. The review of clinical studies demonstrated that survival of teeth with substantial tooth tissue is not influenced by the use of posts. Exceptions were found when only premolars were investigated; in these cases, post placement was associated with greater survival rates in crowned teeth and fewer root fractures in teeth without cusp protection.

Role of H(2)O(2) in hypertension, renin-angiotensin system activation and renal medullary disfunction caused by angiotensin II

BACKGROUND AND PURPOSE

Activation of the intrarenal renin-angiotensin system (RAS) and increased renal medullary hydrogen peroxide (H(2) O(2) ) contribute to hypertension. We examined whether H(2) O(2) mediated hypertension and intrarenal RAS activation induced by angiotensin II (Ang II).

EXPERIMENTAL APPROACH

Ang II (200 ng·kg(-1) ·min(-1) ) or saline were infused in Sprague Dawley rats from day 0 to day 14. Polyethylene glycol (PEG)-catalase (10 000 U·kg(-1) ·day(-1) ) was given to Ang II-treated rats, from day 7 to day 14. Systolic blood pressure was measured throughout the study. H(2) O(2) , angiotensin AT(1) receptor and Nox4 expression and nuclear factor-κB (NF-κB) activation were evaluated in the kidney. Plasma and urinary H(2) O(2) and angiotensinogen were also measured.

KEY RESULTS

Ang II increased H(2) O(2) , AT(1) receptor and Nox4 expression and NF-κB activation in the renal medulla, but not in the cortex. Ang II raised plasma and urinary H(2) O(2) levels, increased urinary angiotensinogen but reduced plasma angiotensinogen. PEG-catalase had a short-term antihypertensive effect and transiently suppressed urinary angiotensinogen. PEG-catalase decreased renal medullary expression of AT(1) receptors and Nox4 in Ang II-infused rats. Renal medullary NF-κB activation was correlated with local H(2) O(2) levels and urinary angiotensinogen excretion. Loss of antihypertensive efficacy was associated with an eightfold increase of plasma angiotensinogen.

CONCLUSIONS AND IMPLICATIONS

The renal medulla is a major target for Ang II-induced redox dysfunction. H(2) O(2) appears to be the key mediator enhancing intrarenal RAS activation and decreasing systemic RAS activity. The specific control of renal medullary H(2) O(2) levels may provide future grounds for the treatment of hypertension.

Alcohol use among 13-year-old adolescents: associated factors and perceptions

OBJECTIVE

To describe the frequency and determinants of alcohol use in a representative sample of 13 years old adolescents, and to analyse qualitatively how adolescents perceive this issue.

STUDY DESIGN

Cross-sectional study with quantitative and qualitative components.

METHODS

Two thousand and thirty-six adolescents attending schools in a city in Portugal were surveyed using a self-reported, structured questionnaire. The qualitative component of the study included 30 semi-structured interviews that intended to assess the reasons for and consequences of drinking as perceived by adolescents, and also the preventive strategies they suggested.

RESULTS

Overall, 50.0% of girls and 44.9% of boys reported that they had experimented with alcohol, and 4.7% of girls and 6.6% of boys drink alcohol at least once per month. Most adolescents recognised that drinking alcohol is harmful and an addiction which is difficult to treat, but this perception was not associated with their own behaviour. Adolescents only identified minor and temporary consequences of drinking alcohol, usually related to very high and acute consumption. In order to prevent alcohol abuse and its consequences, adolescents proposed measures based on strict control, legal restrictions and economic measures, some of which are already in place in Portugal.

CONCLUSION

A high proportion of adolescents had experimented with alcohol by 13 years of age, showing the importance of starting prevention at an early life stage. The results also reflect the importance of reviewing prevention programmes in schools, highlighting the importance of families.

Physical fighting among school-going Portuguese adolescents: social and behavioural correlates

OBJECTIVE

The purpose of this study was to estimate the frequency and to assess the determinants of physical fighting among Portuguese school-going adolescents.

METHODS

A cross-sectional evaluation of urban adolescents born in 1990 and enrolled in public and private schools of Porto was performed in 2007. We identified 3161 17-year-old eligible adolescents and 73.3% accepted to participate. Information was collected using a self-administered questionnaire assessing socio-demographic, behavioural, family and health-related characteristics. The magnitude of the associations between those characteristics and physical fighting was estimated using logistic regression.

RESULTS

Overall, 33.8% of adolescents (48.6% of boys and 20.1% of girls; p < 0.001) engaged in a physical fight during the previous 12 months. The school premises were the most frequently reported setting where fights occurred (girls--41.2% and boys--46.7%, p = 0.179). After adjustment, and in both genders, we found statistically significant associations between physical fighting and grade retention, smoking, drinking and age at first sexual intercourse.

CONCLUSION

Physical fighting among school-going adolescents is frequent, tends to occur at school premises and to cluster with other well recognized adverse health behaviours.

Opposite modulation of astroglial proliferation by adenosine 5'-O-(2-thio)-diphosphate and 2-methylthioadenosine-5'-diphosphate: mechanisms involved

The contribution of P2Y(12,13) receptors to astroglial proliferation was investigated by testing the effects of two agonists with high affinity for these receptors, adenosine 5'-O-(2-thio)-diphosphate (ADPβS) and 2-methylthioadenosine-5'-diphosphate (2-MeSADP), in the incorporation of [(3)H]-thymidine. The effect of ATP, an endogenous inducer of astroglial proliferation, was also investigated. ADPβS and ATP (0.01-1 mM) increased astroglial proliferation up to 282%, an effect inhibited by the P2Y(1) receptor antagonist MRS 2179 (30 μM). The P2Y(12) receptor antagonists MRS 2395 (10 μM) and AR-C 66096 (10 μM) also reduced ADPβS proliferative effect, whereas the effect of ATP was attenuated by the A(2A) and A(2B) receptor antagonists SCH 58261 (30 nM) and MRS 1706 (10 nM), respectively. Studies of the signalling pathway activated showed that ADPβS effect was attenuated by pertussis toxin and by inhibition of phopholipase C (PLC), protein kinase C (PKC) and extracellular signal-regulated kinase1/2 (ERK1/2). The effect of ATP was also attenuated by inhibition of protein kinase A (PKA). The agonist 2-MeSADP (0.001-10 μM) had no effect in astroglial proliferation, but at higher concentrations (0.1-1 mM) it inhibited up to 63%, by mechanisms independent of P2Y(1,12,13) receptors activation. It was metabolised into 2-methylthioadenosine (2-MeSADO), the metabolite responsible for inhibition of astroglial proliferation. The effect of 2-MeSADO (0.1 mM) was attenuated by the A(3) receptors antagonist MRS 1523 (10 μM) and by the inhibitor of nucleoside transporters uridine (0.3 mM). 2-MeSADO did not induce apoptosis but increased lactate dehydrogenase release, an indicator of necrotic cell death. Astroglial proliferation induced by ADPβS was mediated by P2Y(1) and P2Y(12) receptors, leading to activation of PLC-PKC-ERK1/2 signalling pathway. The ATP proliferative effect was also mediated by PKA, supporting the contribution of the A(2) receptors. 2-MeSADP inhibition of astroglial proliferation depended on its conversion into 2-MeSADO, which activated A(3) receptors, blocked [(3)H]-thymidine uptake by astrocytes and led to cell death.

Social representations of smoking behaviour in 13-year-old adolescents

OBJECTIVE

The purpose of this study was to identify adolescents' social representations on smoking using a qualitative approach.

METHODS

Thirty semi-structured interviews were conducted by trained interviewers. The interviews were recorded with participant's permission after our comprehensive explanation of the interview process. After transcript the content of each interview, information was synthesised under each of main question, and a conceptual content analysis was undertaken. The analysis was performed by two of the authors, and the conflicts were resolved by a third person.

RESULTS

Adolescents suggested different explanations for general people and adolescent smoking behaviour. While in general people smoking behaviour was mostly related to dependence, in adolescence it is referred to be associated with status improving among peers and to keep up social relations. We realised that adolescents are aware of the serious health implications of smoking, but they only referred it as a long-term effect in adulthood and no consequences during adolescence were for seen. We also noted the difficulties in giving preventive measures targeted on adolescents.

CONCLUSION

This study points out the importance of peers as agents of socialization in tobacco consumption, and shows the importance of anti-smoking campaigns among this age group with emphasis on smoking consequences in adolescence.

Intestinal 5-hydroxytryptamine and mast cell infiltration in rat experimental colitis

The present study evaluated the extent of dysfunction of the 5-hydroxytryptaminergic system in inflamed (distal colon) and noninflamed segments (jejunum and ileum) after intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) in the rat. Dexamethasone was administered to control rats and TNBS-treated animals before and for 7 days after TNBS treatment. Tissue levels of 5-hydroxytryptamine (5-HT) in the inflamed colon were higher than in controls. The density of mast cells was also markedly increased. Treatment with dexamethasone attenuated the inflammatory response but did not prevent the increase in colonic 5-HT. In the noninflamed jejunum and terminal ileum, 5-HT tissue levels were markedly increased, but treatment with dexamethasone prevented this increase. It is concluded that the increase in 5-HT levels in the inflamed colon in TNBS-induced colitis may result from mast cell infiltration. In the noninflamed intestine, 5-HT tissue levels were also increased, favoring the view of a generalized mast cell infiltration.

Expression and function of LAT1, a neutral amino acid exchanger, in renal porcine epithelial cell line LLC-PK1

AIM

The present study examined the expression of LAT1 and the functional characteristics of the inward and outward [14C] l-leucine transporter in the renal porcine epithelial cell line LLC-PK1.

METHODS

LLC-PK1 cells were cultured in polycarbonate filters and accumulation and transepithelial flux of the substrate monitored with [14C] l-leucine. LAT1 transcripts were examined by RT-PCR. LAT1 protein was detected by immunoblotting.

RESULTS

The accumulation of [14C] l-leucine in the cell and the [14C] l-leucine transepithelial flux were four- and twofold, respectively, when the substrate was added from the basal cell side, suggesting that the basolateral membrane is endowed with a high density of transport units, when compared with the apical membrane. Increases in the transepithelial flux of [14C] l-leucine by unlabelled l-leucine were also more pronounced when unlabelled l-leucine was added from the basolateral membrane. In the absence of Na+, unlabelled l-leucine increased the basal and apical fractional outflow of [14C] l-leucine, this being similar at pH 7.4 and pH 6.2. RT-PCR and immunoblotting detected LAT1 transcript and protein, respectively.

CONCLUSION

LLC-PK1 cells are endowed with the LAT1 transcript and protein and transport l-leucine through the Na+-independent and pH-insensitive LAT1 transporter. The density of transporter units in LLC-PK1 cells may be higher at the basolateral membranes, although be also present in the apical membranes.

Expression of LAT1 and LAT2 amino acid transporters in human and rat intestinal epithelial cells

The present study evaluated the presence of LAT1 and LAT2 amino acid transporters in human Caco-2 cells and rat IEC-6 cells along the mucosa of the rat digestive tract. The LAT1 cDNA was amplified by PCR using two sets of primers (one specific for rat LAT1 and another simultaneously specific for human, rat and mice). The LAT2 cDNA was amplified by PCR using one set of primers simultaneously specific for human, rat and mice LAT2. The presence of LAT1 and LAT2 protein was examined by means of immunoblotting using an antibody raised against the rat LAT1 and mouse LAT2. Caco-2 and IEC-6 cells, as well as the rat intestinal mucosa, are endowed with both LAT1 and LAT2 transporter transcripts and protein. LAT1 protein is most abundant in IEC-6 cells, which is in agreement with functional data previously reported. The findings in the rat intestinal mucosa indicate that LAT1 protein is most abundant in the colon and its abundance markedly decreases at the level of jejunum and ileum, which contrast with relative homogeneous presence of LAT2 across the digestive tract. In conclusion, Caco-2 and IEC-6 cells, as well as the rat intestinal mucosa, are endowed with both LAT1 and LAT2 amino acid transporter transcripts and protein.

Regional intestinal adaptations in Na+,K+-ATPase in experimental colitis and the contrasting effects of interferon-gamma

AIMS

This study evaluated Na+,K+-ATPase activity and the abundance of alpha1 subunit Na+,K+-ATPase in experimental colitis and gathered evidence on the effects of interferon-gamma (IFN-gamma) on intestinal Na+,K+-ATPase.

METHODS

Colitis was induced by the intrarectal administration of 2,4,6-trinitrobenzene sulphonic acid (TNBS, 30 mg/250 microL). Na+,K+-ATPase activity was determined as the difference between total and ouabain-insensitive ATPase. The abundance of Na+,K+-ATPase was analysed by immunoblotting.

RESULTS

Na+,K+-ATPase activity was markedly reduced in the proximal colonic mucosa of TNBS-treated rats, whereas upstream in the terminal ileal mucosa a marked increase in sodium pump activity was observed. At the jejunal level no significant changes in Na+,K+-ATPase activity were observed between TNBS-treated rats and corresponding controls (ethanol-treated rats). No changes were observed in the abundance of alpha1 subunit Na+,K+-ATPase in the proximal colon, terminal ileum and jejunum. The administration of IFN-gamma (50,000 U) 48 h before sacrifice reduced both Na+,K+-ATPase activity and the abundance of alpha1 subunit Na+,K+-ATPase in the proximal colon. Dexamethasone prevented colonic inflammation and decreases in proximal colonic Na+,K+-ATPase activity in TNBS-treated rats, but did not affect the INF-gamma-induced decrease in colonic Na+,K+-ATPase activity.

CONCLUSIONS

The increase in ileal Na+,K+-ATPase activity upstream to the lesioned colonic mucosa, where Na+,K+-ATPase activity was markedly reduced, might indicate a compensatory process to counteract the decrease in water and electrolyte absorption at the colonic level. This decrease in colonic Na+,K+-ATPase activity is likely not related to INF-gamma-induced downregulation of Na+,K+-ATPase.

Decreased availability of intestinal dopamine in transmural colitis may relate to inhibitory effects of interferon-gamma upon L-DOPA uptake

AIMS

The present study aimed to evaluate the relationship between intestinal inflammation, interferon-gamma (IFN-gamma) levels and intestinal levels of dopamine, its precursor l-3,4-dihydroxyphenylalanine (L-DOPA), and the activity of aromatic L-amino acid decarboxylase (AADC) activity along the digestive tract in a rat experimental model of colitis.

METHODS

Colitis was induced by rectal administration of 2,4,6-trinitrobenzene sulphonic acid (TNBS). Catechol derivatives were assayed by means of HPLC-EC.

RESULTS

It is shown that dopamine and noradrenaline levels in the distal colon (inflamed mucosa), but not in the ileum (non-inflamed mucosa), of TNBS-treated rats were markedly lower than in control animals. A slight decrease in L-DOPA tissue levels, no changes in AADC activity and an increase in plasma IFN-gamma levels accompanied this decrease in dopamine levels. Exposure of Caco-2 cells, a human intestinal epithelial cell line, to human IFN-gamma resulted in a concentration-dependent and long-lasting inhibition of L-DOPA uptake, which most likely explains the decrease in dopamine levels in the inflamed mucosa.

CONCLUSION

Changes in tissue levels of noradrenaline and dopamine in experimental colitis in the rat follow a similar pattern to that observed in patients with Crohn's disease and ulcerative colitis. In this model of experimental colitis, the decrease in dopamine levels is most likely explained by the inhibitory effect of IFN-gamma on L-DOPA uptake by intestinal epithelial cells.

Are beta-sheet breaker peptides dissolving the therapeutic problem of Alzheimer's disease?

Alzheimer's disease (AD) is a neurodegenerative disorder for which there is no cure or effective treatment. One of the major neuropathological signatures of AD is the deposition of amyloid plaques in the brain of affected people. Although the role of these structures in the pathogenesis of the disease is not fully understood, recent findings have provided evidence that amyloid may be a key player in the disease. Therefore, preventing and reversing cerebral amyloid deposition have become an attractive therapeutic strategy for AD. We have engineered synthetic beta-sheet breaker peptides to bind soluble amyloid peptide and prevent and reverse its conversion to the beta-sheet rich aggregated structure, precursor of the amyloid plaques. Results in vitro, in cell culture and in vivo suggest that beta-sheet breaker peptides might be candidates for an AD-therapy focused to reduce amyloid deposition.

Regulation of apical transporter of L-DOPA in human intestinal Caco-2 cells

The present study examined the nature of the apical inward L-3,4-dihydroxyphenylalanine (L-DOPA) transporter in human intestinal epithelial Caco-2 cells, and whether protein kinases modulate the activity of this transporter. The apical inward transfer of L-DOPA was promoted through an energy-dependent and sodium-insensitive transporter (Km=33 microM; Vmax=2932 pmol/mg protein/6 min). This transporter was insensitive to N-(methylamino)-isobutyric acid, but competitively inhibited by 2-aminobicyclo(2,2,1)-heptane-2-carboxylic acid (BCH; IC50=83 microM). The organic cation inhibitor decynium 24 failed to affect the accumulation of L-DOPA, whereas the organic anion inhibitor 4,4'-diisothiocynatostilbene-2,2'-disulphonic acid (DIDS) competitively inhibited L-DOPA uptake (IC50=83 microM). However, the apical-to-basal and basal-to-apical transepithelial transport and the cell accumulation of [3H]-PAH was close to that of [14C]-sorbitol and insensitive to DIDS (300 microM). Modulators of protein kinase A (PKA) [cyclic adenosine monophosphate (cAMP), forskolin, H-89 and cholera toxin], protein kinase G (PKG) [cyclic guanosine monophosphate (GMP), zaprinast, LY 83583 and sodium nitroprusside] and protein kinase C (PKC) (phorbol 12,13-dibutirate and chelerythrine) failed to affect the accumulation of L-DOPA. The Ca2+/calmodulin inhibitors calmidazolium and trifluoperazine inhibited L-DOPA uptake (IC50s of 53 and 252 microM, respectively), but the rise of intracellular Ca2+ by A23187 (1 microM) and thapsigargin (1 microM) played no role on L-DOPA uptake. It is concluded that Caco-2 cells take up L-DOPA over the apical cell border through the sodium-independent and pH-sensitive L-type amino acid transporter.

Evidence of saxitoxin derivatives as causative agents in the 1997 mass mortality of monk seals in the Cape Blanc Peninsula

Monk seals in Cape Blanc (Western Sahara coast) suffered a mass mortality during May-July 1997 which was attributed to a morbillivirus. High performance liquid chromatography (HPLC) analysis on tissues of seals killed during the outbreak and on related fauna showed peaks with retention times coincident with those of some saxitoxin derivatives but their identity was not proved. Here we present results of further HPLC analyses that unambiguously prove the identity of these toxins by mass spectrometry (MS), supporting the hypothesis that this mortality of monk seals was caused by biotoxins rather than by a morbillivirus.