Functional and structural responses of plankton communities toward consecutive experimental heatwaves in Mediterranean coastal waters

The frequency of marine heatwaves (HWs) is projected to increase in the Mediterranean Sea over the next decades. An in situ mesocosm experiment was performed in a Mediterranean lagoon for 33 days. Three mesocosms were used as controls following the natural temperature of the lagoon. In three others, two HWs of + 5 °C compared to the controls were applied from experimental day (d) 1 to d5 (HW1) and from d11 to d15 (HW2). High-frequency data of oxygen, chlorophyll-a (chl-a), temperature, salinity and light from sensors immersed in all mesocosms were used to calculate gross primary production (GPP), respiration (R) and phytoplankton growth (µ) and loss (L) rates. Nutrients and phytoplankton community structure from pigments were also analyzed. HW1 significantly increased GPP, R, chl-a, µ and L by 7 to 38%. HW2 shifted the system toward heterotrophy by only enhancing R. Thus, the effects of the first HW resulted in the attenuation of those of a second HW on phytoplankton processes, but not on community respiration, which was strongly regulated by temperature. In addition, natural phytoplankton succession from diatoms to haptophytes was altered by both HWs as cyanobacteria and chlorophytes were favored at the expense of haptophytes. These results indicate that HWs have pronounced effects on Mediterranean plankton communities.

Early treatment with JNJ-46356479, a mGluR2 modulator, improves behavioral and neuropathological deficits in a postnatal ketamine mouse model of schizophrenia

Positive allosteric modulators of the metabotropic glutamate receptor 2 (mGluR2), such as JNJ-46356479 (JNJ), may mitigate the glutamate storm during the early stages of schizophrenia (SZ), which could be especially useful in the treatment of cognitive and negative symptoms. We evaluated the efficacy of early treatment with JNJ or clozapine (CLZ) in reversing behavioral and neuropathological deficits induced in a postnatal ketamine (KET) mouse model of SZ. Mice exposed to KET (30 mg/kg) on postnatal days (PND) 7, 9, and 11 received JNJ or CLZ (10 mg/kg) daily in the adolescent period (PND 35-60). Mice exposed to KET did not show the expected preference for a novel object or for social novelty, but they recovered this preference with JNJ treatment. Similarly, KET group did not show the expected dishabituation in the fifth trial, but mice treated with JNJ or CLZ recovered an interest in the novel animal. Neuronal immunoreactivity also differed between treatment groups with mice exposed to KET showing a reduction in parvalbumin positive cells in the prefrontal cortex and decreased c-Fos expression in the hippocampus, which was normalized with the pharmacological treatment. JNJ-46356479 treatment in early stages may help improve the cognitive and negative symptoms, as well as certain neuropathological deficits, and may even obtain a better response than CLZ treatment. This may have relevant clinical translational applications since early treatment with mGluR2 modulators that inhibit glutamate release at the onset of critical phases of SZ may prevent or slow down the clinical deterioration of the disease.

Metabolic responses of plankton to warming during different productive seasons in coastal Mediterranean waters revealed by in situ mesocosm experiments

The response of coastal lagoon plankton communities to warming was studied during two in situ mesocosm experiments in spring and fall of 2018 in the Mediterranean. Phytoplankton biomass, gross primary production (GPP), community respiration (R), phytoplankton growth (µ), and loss (l) rates were estimated using high-frequency chlorophyll-a fluorescence and dissolved oxygen sensors, and daily sampling was used to evaluate the nutrient status and phytoplankton pigment functional groups. Warming strongly depressed the dominant phytoplankton functional groups, mainly the prymnesiophytes, diatoms (spring), and green flagellates (fall). It favored minor groups such as the dinoflagellates (spring) and diatoms (fall). In spring, warming depressed GPP and R by half; however, µ (+ 18%) and l (+ 37%) were enhanced. In contrast, both GPP and µ were enhanced by 21% and 28%, respectively, in fall, and no effects were observed for R and l. Warming strongly decreased phytoplankton biomass and oxygen production in spring, and enhanced them, to a lesser extent, in fall. This led to an overall loss of production over both seasons. This study improves understanding of the contrasting effects of warming during two productive seasons, which depend on plankton community composition and interactions between components and environmental conditions.

A longitudinal study of gene expression in first-episode schizophrenia; exploring relapse mechanisms by co-expression analysis in peripheral blood

Little is known about the pathophysiological mechanisms of relapse in first-episode schizophrenia, which limits the study of potential biomarkers. To explore relapse mechanisms and identify potential biomarkers for relapse prediction, we analyzed gene expression in peripheral blood in a cohort of first-episode schizophrenia patients with less than 5 years of evolution who had been evaluated over a 3-year follow-up period. A total of 91 participants of the 2EPs project formed the sample for baseline gene expression analysis. Of these, 67 provided biological samples at follow-up (36 after 3 years and 31 at relapse). Gene expression was assessed using the Clariom S Human Array. Weighted gene co-expression network analysis was applied to identify modules of co-expressed genes and to analyze their preservation after 3 years of follow-up or at relapse. Among the 25 modules identified, one module was semi-conserved at relapse (DarkTurquoise) and was enriched with risk genes for schizophrenia, showing a dysregulation of the TCF4 gene network in the module. Two modules were semi-conserved both at relapse and after 3 years of follow-up (DarkRed and DarkGrey) and were found to be biologically associated with protein modification and protein location processes. Higher expression of DarkRed genes was associated with higher risk of suffering a relapse and early appearance of relapse (p = 0.045). Our findings suggest that a dysregulation of the TCF4 network could be an important step in the biological process that leads to relapse and suggest that genes related to the ubiquitin proteosome system could be potential biomarkers of relapse.

Co-occurrence networks reveal the central role of temperature in structuring the plankton community of the Thau Lagoon

To identify the environmental factors that drive plankton community composition and structure in coastal waters, a shallow northwestern Mediterranean lagoon was monitored from winter to spring in two contrasting years. The campaign was based on high-frequency recordings of hydrological and meteorological parameters and weekly samplings of nutrients and the plankton community. The collected data allowed the construction of correlation networks, which revealed that water temperature was the most important factor governing community composition, structure and succession at different trophic levels, suggesting its ubiquitous food web control. Temperature favoured phytoplanktonic flagellates (Cryptophyceae, Chrysophyceae, and Chlorophyceae) and ciliates during winter and early spring. In contrast, it favoured Bacillariophyceae, dinoflagellates, phytoplankton < 6 µm and aloricate Choreotrichida during spring. The secondary factors were light, which influenced phytoplankton, and wind, which may regulate turbidity and the nutrient supply from land or sediment, thus affecting benthic species such as Nitzschia sp. and Uronema sp. or salinity-tolerant species such as Prorocentrum sp. The central role of temperature in structuring the co-occurrence network suggests that future global warming could deeply modify plankton communities in shallow coastal zones, affecting whole-food web functioning.

In situ characterisation of pathogen dynamics during a Pacific oyster mortality syndrome episode

Significant mortality of Crassostrea gigas juveniles is observed systematically every year worldwide. Pacific Oyster Mortality Syndrome (POMS) is caused by Ostreid Herpesvirus 1 (OsHV-1) infection leading to immune suppression, followed by bacteraemia caused by a consortium of opportunistic bacteria. Using an in-situ approach and pelagic chambers, our aim in this study was to identify pathogen dynamics in oyster flesh and in the water column during the course of a mortality episode in the Mediterranean Thau lagoon (France). OsHV-1 concentrations in oyster flesh increased before the first clinical symptoms of the disease appeared, reached maximum concentrations during the moribund phase and the mortality peak. The structure of the bacterial community associated with oyster flesh changed in favour of bacterial genera previously associated with oyster mortality including Vibrio, Arcobacter, Psychrobium, and Psychrilyobacter. During the oyster mortality episode, releases of OsHV-1 and opportunistic bacteria were observed, in succession, in the water surrounding the oyster lanterns. These releases may favour the spread of disease within oyster farms and potentially impact other marine species, thereby reducing marine biodiversity in shellfish farming areas.

The usefulness of Olanzapine plasma concentrations in monitoring treatment efficacy and metabolic disturbances in first-episode psychosis

INTRODUCTION

The role of Olanzapine therapeutic drug monitoring is controversial. The present study explores the associations of Olanzapine plasma concentrations with clinical response and metabolic side effects in first episode psychosis (FEP) after 2 months of treatment.

METHODS

Forty-seven patients were included. Improvement in clinical symptomatology was assessed using the PANSS. Metabolic assessment included weight, blood pressure, waist circumference, blood glucose, total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides.

RESULTS

The Olanzapine plasma concentrations after 2 months of treatment were positively correlated with weight gain (r = 0.49, p = 0.003), and a concentration > 23.28 ng/mL was identified as a positive predictor of weight gain (≥ 7%). The Olanzapine concentration to dose (C/D) ratio was positively correlated with the percentage of improvement in the total PANSS (r = 0.46, p = 0.004), and a C/D ratio > 2.12 was identified as a positive predictor of a good response (percentage of improvement > 30%) after 2 months of treatment. We also identified several factors that could alter Olanzapine pharmacokinetics: gender (p = 0.03), diagnosis (p = 0.05), smoking habit (p = 0.05), and co-medications such as valproic acid (p = 0.05) and anxiolytics (p = 0.01).

DISCUSSION

In conclusion, our results suggest that therapeutic drug monitoring of Olanzapine could be helpful to evaluate therapeutic efficacy and metabolic dysfunction in FEP patients treated with Olanzapine.

Surface ocean microbiota determine cloud precursors

One pathway by which the oceans influence climate is via the emission of sea spray that may subsequently influence cloud properties. Sea spray emissions are known to be dependent on atmospheric and oceanic physicochemical parameters, but the potential role of ocean biology on sea spray fluxes remains poorly characterized. Here we show a consistent significant relationship between seawater nanophytoplankton cell abundances and sea-spray derived Cloud Condensation Nuclei (CCN) number fluxes, generated using water from three different oceanic regions. This sensitivity of CCN number fluxes to ocean biology is currently unaccounted for in climate models yet our measurements indicate that it influences fluxes by more than one order of magnitude over the range of phytoplankton investigated.

Spanish translation and linguistic validation of the North Star Ambulatory Assessment for Duchenne muscular dystrophy functional evaluation

INTRODUCTION

There is a need for reliable and properly validated outcome measures in Duchenne muscular dystrophy, both to monitor functional impairment and to assess the impact of new therapies.

OBJECTIVE

We aimed to perform a translation of the North Star Ambulatory Assessment scale into Spanish and a linguistic validation of the resulting Spanish version.

MATERIALS AND METHODS

A structured multistage process based on international guidelines was used, with the following steps: translation (preparation, forward translation, reconciliation, back translation, back translation review, clinicians' review), linguistic validation though pilot testing (cognitive interviewing, medical review, review of results and final changes), and finalization (proofreading, final report).

RESULTS

No major difficulties were found during translation steps. Few changes were needed to reconcile forward translations. The linguistic validation process required several meetings to solve comprehension difficulties due to subtle nuances in the meaning of some words. The pilot study was carried out in 10 practitioners from different places in Spain, including both physiotherapists and specialists and registrars in physical medicine and rehabilitation. A total of 6 comments were obtained, including 2 comments on starting positions for items 4-5 (stand on one leg) and item 10 (stand on heels) and 2 comments on scoring instructions for item 3 (stand up from chair) and item 14 (jump).

CONCLUSION

Our study has resulted in a convenient and reliable instrument for the quantification of functional abilities in boys with Duchenne muscular dystrophy in Spain. Our innovations in methods and our results could be used as a suggested template for the North Star Ambulatory Assessment linguistic validation in other languages.

Brief Hospital Supervision of Exercise and Diet During Adjuvant Breast Cancer Therapy Is Not Enough to Relieve Fatigue: A Multicenter Randomized Controlled Trial

Supervised exercise dietary programs are recommended to relieve cancer-related fatigue and weight increase induced by adjuvant treatment of early breast cancer (EBC). As this recommendation lacks a high level of evidence, we designed a multicenter randomized trial to evaluate the impact of an Adapted Physical Activity Diet (APAD) education program on fatigue. We randomized 360 women with EBC who were receiving adjuvant chemotherapy and radiotherapy to APAD or usual care at eight French cancer institutions. Data were collected at baseline, end of chemotherapy, end of radiotherapy, and 6 months post-treatment. The primary endpoint was the general cancer-related fatigue score using the MFI-20 questionnaire. Fatigue correlated with the level of precariousness, but we found no significant difference between the two groups in terms of general fatigue (p = 0.274). The APAD arm has a smaller proportion of patients with confirmed depression at the end of follow-up (p = 0.052). A transient modification in physical activity levels and dietary intake was reported in the experimental arm. However, a mixed hospital- and home-based APAD education program is not enough to improve fatigue caused by adjuvant treatment of EBC. Cancer care centers should consider integrating more proactive diet-exercise supportive care in this population, focusing on precarious patients.

Personalized medicine begins with the phenotype: identifying antipsychotic response phenotypes in a first-episode psychosis cohort

AIMS

Here, we present a clustering strategy to identify phenotypes of antipsychotic (AP) response by using longitudinal data from patients presenting first-episode psychosis (FEP).

METHOD

One hundred and ninety FEP with complete data were selected from the PEPs project. The efficacy was assessed using total PANSS, and adverse effects using total UKU, during one-year follow-up. We used the Klm3D method to cluster longitudinal data.

RESULTS

We identified four clusters: cluster A, drug not toxic and beneficial; cluster B, drug beneficial but toxic; cluster C, drug neither toxic nor beneficial; and cluster D, drug toxic and not beneficial. These groups significantly differ in baseline demographics, clinical, and neuropsychological characteristics (PAS, total PANSS, DUP, insight, pIQ, age of onset, cocaine use and family history of mental illness).

CONCLUSIONS

The results presented here allow the identification of phenotypes of AP response that differ in well-known simple and classic clinical variables opening the door to clinical prediction and application of personalized medicine.

Understanding barriers and facilitators to participation in colorectal cancer screening: A French qualitative study

Based on the theory of social representations, this study aims to identify the main determinants to participation in colorectal cancer screening. Six focus groups (N = 29 participants belonging to the general population) were conducted, followed by a theoretical thematic analysis. Screening obstacles are a lack of test's accessibility, a low preoccupation for prevention and the negative image of colorectal cancer. Conversely, screening facilitators are the ease of the new test, being encouraged to get screened and appointment reminder. This study advances understanding of adherence to screening by addressing the beliefs and knowledge surrounding it.

Use of physiological information based on grayscale images to improve mass spectrometry imaging data analysis from biological tissues

The characterization of cancer tissues by matrix-assisted laser desorption ionization-mass spectrometry images (MALDI-MSI) is of great interest because of the power of MALDI-MS to understand the composition of biological samples and the imaging side that allows for setting spatial boundaries among tissues of different nature based on their compositional differences. In tissue-based cancer research, information on the spatial location of necrotic/tumoral cell populations can be approximately known from grayscale images of the scanned tissue slices. This study proposes as a major novelty the introduction of this physiologically-based information to help in the performance of unmixing methods, oriented to extract the MS signatures and distribution maps of the different tissues present in biological samples. Specifically, the information gathered from grayscale images will be used as a local rank constraint in Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) for the analysis of MALDI-MSI of cancer tissues. The use of this constraint, setting absence of certain kind of tissues only in clear zones of the image, will help to improve the performance of MCR-ALS and to provide a more reliable definition of the chemical MS fingerprint and location of the tissues of interest. The general strategy to address the analysis of MALDI-MSI of cancer tissues will involve the study of the MCR-ALS results and the posterior use of MCR-ALS scores as dimensionality reduction for image segmentation based on K-means clustering. The resolution method will provide the MS signatures and their distribution maps for each tissue in the sample. Then, the resolved distribution maps for each biological component (MCR scores) will be submitted as initial information to K-means clustering for image segmentation to obtain information on the boundaries of the different tissular regions in the samples studied. MCR-ALS prior to K-means not only provides the desired dimensionality reduction, but additionally resolved non-biological signal contributions are not used and the weight given to the different biological components in the segmentation process can be modulated by suitable preprocessing methods.

P3720Cerebral near-infrared spectroscopy monitoring during transcatheter aortic valve implantation

Introduction

Stroke and transient ischemic attack (TIA) are important periprocedural cerebrovascular complications of transcatheter aortic valve implantation (TAVI). Regional cerebral O2 saturation is an indicator for cerebral perfusion and can be measured in real-time and noninvasively by near-infrared spectroscopy (NIRS). In this pilot study we evaluated the feasibility and utility of NIRS during TAVI.

Methods

Regional cerebral O2 saturation (rScO2, bihemispheric) was measured by near-infrared spectroscopy during 32 transfemoral TAVI procedures (female 56.3%, mean age 81.8 years). All patients received conscious sedation and O2-supplement if peripheral oxygen saturation (SpO2) was below 95%. Baseline rScO2 was measured at the beginning of the procedure, as well as before, during and 5min after rapid pacing for valve deployment.

Results

Mean preoperative mini mental state examination score was 26.5 points (theoretically max. 30 points, >24 points no severe cognitive impairment). Two-third of the patients (n=21) required oxygen supply (mean 4.0 l/min) during the TAVI procedure. Mean baseline rScO2 was 59.3% with no differences between both cerebral hemispheres (left 60.3% vs. right 58.7% p=0.23). Compared to baseline rScO2 and rScO2 assessed immediately before rapid passing, rScO2 dropped significantly during rapid pacing (59.3% vs. 51.8%, p<0.01 and 60.9% vs. 51.8%, p<0.01 respectively). Five minutes after rapid pacing rScO2 values had normalized again (post rapid pacing 60.9% vs. 51.8% during rapid pacing, p<0.01; baseline 59.3% vs. post rapid pacing 60.9%, p=0.51). Intraprocedural cerebrovascular events were observed in two cases. One patient developed a left-sided hemiplegia (stroke, later verified by cerebral CT scan) and one patient a transient tremor of the left upper extremity (TIA, new hemorrhagic or ischemic event ruled out by cerebral CT scan). In both cases we observed an abnormal sudden rScO2 decrement by the corresponding right hemispheric NIRS sensor (left-right hemisphere sensor: 60% vs. 44% and 63% vs. 48% respectively).

Conclusion

Regional cerebral O2 saturation, an indicator for cerebral perfusion, decreases significantly during rapid pacing of TAVI procedure. Furthermore, rScO2 measurement by NIRS may be helpful to detect cerebrovascular complications early during TAVI procedure.

Water temperature drives phytoplankton blooms in coastal waters

Phytoplankton blooms are an important, widespread phenomenon in open oceans, coastal waters and freshwaters, supporting food webs and essential ecosystem services. Blooms are even more important in exploited coastal waters for maintaining high resource production. However, the environmental factors driving blooms in shallow productive coastal waters are still unclear, making it difficult to assess how environmental fluctuations influence bloom phenology and productivity. To gain insights into bloom phenology, Chl a fluorescence and meteorological and hydrological parameters were monitored at high-frequency (15 min) and nutrient concentrations and phytoplankton abundance and diversity, were monitored weekly in a typical Mediterranean shallow coastal system (Thau Lagoon). This study was carried out from winter to late spring in two successive years with different climatic conditions: 2014/2015 was typical, but the winter of 2015/2016 was the warmest on record. Rising water temperature was the main driver of phytoplankton blooms. However, blooms were sometimes correlated with winds and sometimes correlated with salinity, suggesting nutrients were supplied by water transport via winds, saltier seawater intake, rain and water flow events. This finding indicates the joint role of these factors in determining the success of phytoplankton blooms. Furthermore, interannual variability showed that winter water temperature was higher in 2016 than in 2015, resulting in lower phytoplankton biomass accumulation in the following spring. Moreover, the phytoplankton abundances and diversity also changed: cyanobacteria (< 1 μm), picoeukaryotes (< 1 μm) and nanoeukaryotes (3–6 μm) increased to the detriment of larger phytoplankton such as diatoms. Water temperature is a key factor affecting phytoplankton bloom dynamics in shallow productive coastal waters and could become crucial with future global warming by modifying bloom phenology and changing phytoplankton community structure, in turn affecting the entire food web and ecosystem services.

Why do women fast during breast cancer chemotherapy? A qualitative study of the patient experience

BACKGROUND

Why do patients practice fasting? The effects of fasting before treatment with chemotherapy for cancer in humans are currently unknown. However, there is an apparent enthusiasm for fasting among cancer patients. This qualitative study provides data on the motivations to fast and the experience of fasting among a population of women with breast cancer.

METHOD

Sixteen semi-structured interviews were conducted, and two researchers independently performed a thematic analysis. To ensure the internal validity of the study, patients had the possibility to rate their agreement with the study results through a satisfaction questionnaire.

RESULTS

Six main themes were identified in this study: main reasons to fast, alternative authorities to the oncologist, adapting the fast to social and lifestyle constraints, fasting effects felt during chemotherapy, barriers and facilitators of fasting during chemotherapy, and seeking for a more integrative medicine. Patients' primary motivation to fast was to lower the negative side effects of chemotherapy. Fasting was also reported as a coping strategy to give them a greater sense of control over their treatment and to reduce their anxiety.

CLINICAL IMPLICATIONS

Results from the study suggest that, if discouraged from fasting, patients may turn to complementary health care practitioners for support. Medical professionals may thus not know of patients' fasting practice. Health psychologists could play a key role fostering the dialogue between different health professionals and the patient. They could also help to meet patients' needs during cancer treatment to reduce treatment anxiety. Statement of contribution What is already known on this subject? Fasting diet in cancer treatment has become an important topic since Raffaghello et al. published their study on mice in 2008. While the (positive) effects of fasting in humans remain to be proven, there has been a significant enthusiasm for this practice among patients in the last few years. However, patients' motivations to fast remain unclear to the scientific community and clinicians. What does this study add? This study is the first to investigate patients' motivations to fast and patients' experience of fasting in a cancer population. Patients' primary motivation to fast was to lower the side effects of chemotherapy. Fasting acts as an active coping strategy that helps to reduce anxiety. Unsupported patients may turn to complementary health care practitioners.

Determinants of physical activity promotion by smoking cessation advisors

OBJECTIVE

To investigate the cross-sectional association between personal physical activity (PA) level, Theory of Planned Behavior (TPB) constructs toward PA promotion, and PA promotion behavior among smoking cessation advisors.

METHOD

149 smoking cessation advisors were invited to complete online questionnaires. Hypotheses were tested using Bayesian path analysis.

RESULTS

Attitudes and perceived behavioral control (PBC) of smoking cessation advisors were related to PA promotion intentions; intentions were in turn related to PA promotion behaviors. Advisors' personal PA level was indirectly associated with PA promotion behaviors through PBC and PA promotion intentions.

CONCLUSION

The TPB is a relevant theoretical framework with which to explore determinants of PA promotion behavior among smoking cessation advisors. The PA level of health care professionals may be linked to PA promotion behavior through some TPB constructs.

PRACTICE IMPLICATIONS

Smoking cessation advisor training should include education on attitude development (e.g., PA benefits on smoking cessation), PBC (e.g., modality of PA prescription) and PA promotion intentions (e.g., goal setting). Smoking cessation advisors should also be encouraged to regularly practice PA in order to improve their PA promotion behaviors.

Significant Change in Marine Plankton Structure and Carbon Production After the Addition of River Water in a Mesocosm Experiment

Rivers are known to be major contributors to eutrophication in marine coastal waters, but little is known on the short-term impact of freshwater surges on the structure and functioning of the marine plankton community. The effect of adding river water, reducing the salinity by 15 and 30%, on an autumn plankton community in a Mediterranean coastal lagoon (Thau Lagoon, France) was determined during a 6-day mesocosm experiment. Adding river water brought not only nutrients but also chlorophyceans that did not survive in the brackish mesocosm waters. The addition of water led to initial increases (days 1-2) in bacterial production as well as increases in the abundances of bacterioplankton and picoeukaryotes. After day 3, the increases were more significant for diatoms and dinoflagellates that were already present in the Thau Lagoon water (mainly Pseudo-nitzschia spp. group delicatissima and Prorocentrum triestinum) and other larger organisms (tintinnids, rotifers). At the same time, the abundances of bacterioplankton, cyanobacteria, and picoeukaryote fell, some nutrients (NH₄⁺, SiO₄^3-) returned to pre-input levels, and the plankton structure moved from a trophic food web based on secondary production to the accumulation of primary producers in the mesocosms with added river water. Our results also show that, after freshwater inputs, there is rapid emergence of plankton species that are potentially harmful to living organisms. This suggests that flash flood events may lead to sanitary issues, other than pathogens, in exploited marine areas.

Pharmacogenetic study of antipsychotic induced acute extrapyramidal symptoms in a first episode psychosis cohort: role of dopamine, serotonin and glutamate candidate genes

This study investigated whether the risk of presenting antipsychotic (AP)-induced extrapyramidal symptoms (EPS) could be related to single-nucleotide polymorphisms (SNPs) in a naturalistic cohort of first episode psychosis (FEP) patients. Two hundred and two SNPs in 31 candidate genes (involved in dopamine, serotonin and glutamate pathways) were analyzed in the present study. One hundred and thirteen FEP patients (43 presenting EPS and 70 non-presenting EPS) treated with high-potency AP (amisulpride, paliperidone, risperidone and ziprasidone) were included in the analysis. The statistical analysis was adjusted by age, gender, AP dosage, AP combinations and concomitant treatments as covariates. Four SNPs in different genes (DRD2, SLC18A2, HTR2A and GRIK3) contributed significantly to the risk of EPS after correction for multiple testing (P<1 × 10(-4)). These findings support the involvement of dopamine, serotonin and glutamate pathways in AP-induced EPS.

One-Year Follow-up of Children and Adolescents with Major Depressive Disorder: Relationship between Clinical Variables and Abcb1 Gene Polymorphisms

Introduction: Differences in response to fluoxetine (FLX) may be influenced by certain genes that are involved in FLX transportation (ABCB1). We examined remission and recovery from the index episode in a cohort of patients treated with FLX, and also investigated associations between genetic variants in ABCB1 and remission, recovery, and suicide risk.

Methods: This was a naturalistic 1-year follow-up study of 46 adolescents diagnosed with major depressive disorder (MDD). At 12 months they underwent a diagnostic interview with the K-SADS-PL.

Results: It was found that remission was around 69.5% and recovery 56.5%. Remission and recovery were associated with lower scores on the CDI at baseline, with fewer readmissions and suicide attempts, and with lower scores on the CGI and higher scores on the GAF scale. No relationship was found between ABCB1 and remission or recovery. However, a significant association was observed between the G2677T ABCB1 polymorphism and suicide attempts.

Conclusion: Other factors such as stressful events, family support, and other genetic factors are likely to be involved in MDD outcome.

Simulation Method Linking Dense Microalgal Culture Spectral Properties in the 400-750 nm Range to the Physiology of the Cells

This work describes a method to model the optical properties over the (400-750 nm) spectral range of a dense microalgal culture using the chemical and physical properties of the algal cells. The method was based on a specific program called AlgaSim coupled with the adding-doubling method: at the individual cell scale, AlgaSim simulates the spectral properties of one model, three-layer spherical algal cell from its size and chemical composition. As a second step, the adding-doubling method makes it possible to retrieve the total transmittance of the algal medium from the optical properties of the individual algal cells. The method was tested by comparing the simulated total transmittance spectra for dense marine microalgal cultures of Isochrysis galbana (small flagellates) and Phaeodactylum tricornutum (diatoms) to spectra measured using an experimental spectrophotometric setup. Our study revealed that the total transmittance spectra simulated for the quasi-spherical cells of Isochrysis galbana were in good agreement with the measured spectra over the whole spectral range. For Phaeodactylum tricornutum, large differences between simulated and measured spectra were observed over the blue part of the transmittance spectra, probably due to non-spherical shape of the algal cells. Prediction of the algal cell density, mean size and pigment composition from the total transmittance spectra measured on algal samples was also investigated using the reversal of the method. Mean cell size was successfully predicted for both species. The cell density was also successfully predicted for spherical Isochrysis galbana, with a relative error below 7%, but not for elongated Phaeodactylum tricornutum with a relative error up to 26%. The pigments total quantity and composition, the carotenoids:chlorophyll ratio in particular, were also successfully predicted for Isochrysis galbana with a relative error below 8%. However, the pigment predictions and measurements for Phaeodactylum tricornutum showed large discrepancies, with a relative error up to 88%. These results give strong support for the development of a promising tool providing rapid and accurate estimations of biomass and physiological status of a dense microalgal culture based on only light transmittance properties.

Exon-focused genome-wide association study of obsessive-compulsive disorder and shared polygenic risk with schizophrenia

Common single-nucleotide polymorphisms (SNPs) account for a large proportion of the heritability of obsessive-compulsive disorder (OCD). Co-ocurrence of OCD and schizophrenia is commoner than expected based on their respective prevalences, complicating the clinical management of patients. This study addresses two main objectives: to identify particular genes associated with OCD by SNP-based and gene-based tests; and to test the existence of a polygenic risk shared with schizophrenia. The primary analysis was an exon-focused genome-wide association study of 370 OCD cases and 443 controls from Spain. A polygenic risk model based on the Psychiatric Genetics Consortium schizophrenia data set (PGC-SCZ2) was tested in our OCD data. A polygenic risk model based on our OCD data was tested on previous data of schizophrenia from our group. The most significant association at the gene-based test was found at DNM3 (P=7.9 × 10(-5)), a gene involved in synaptic vesicle endocytosis. The polygenic risk model from PGC-SCZ2 data was strongly associated with disease status in our OCD sample, reaching its most significant value after removal of the major histocompatibility complex region (lowest P=2.3 × 10(-6), explaining 3.7% of the variance). The shared polygenic risk was confirmed in our schizophrenia data. In conclusion, DNM3 may be involved in risk to OCD. The shared polygenic risk between schizophrenia and OCD may be partially responsible for the frequent comorbidity of both disorders, explaining epidemiological data on cross-disorder risk. This common etiology may have clinical implications.

Variation in allergen content in sublingual allergen immunotherapy with house dust mites

Background

Allergen immunotherapy is a treatment modality which can be applied using different vaccines. The aim of this study was to quantify and compare the allergen content of different house dust mites (HDM)’ sublingual treatments and to review the evidence on their efficacy.

Methods

Five sublingual allergen immunotherapy (SLIT) products were ordered and purchased at an ordinary pharmacy and masked for blinding before the study was started. Detection of Dermatophagoides pteronyssinus and Dermatophagoides farinae allergens Der p 1, Der f 1, Der p 2 and Der f 2 was carried out by immunoblotting and fluorescent multiplex. A literature search for meta‐analyses and systematic reviews that included SLIT‐HDM products was performed.

Results

Der p 1 concentrations ranged from 0.6 to 14.5 μg/ml; similar figures were found for Der f 1 that ranged from 0.2 to 12.4 μg/ml. Der p 2+ Der f 2 ranged from 0.2 to 1.5 μg/ml. Data on efficacy are scarce for most of the five products.

Conclusions

Substantial variations regarding allergen content were found among these five SLIT‐HDM products. Therefore, it can be necessary to guarantee the quality of the SLIT‐HDM products and to demonstrate their effectiveness before they are marketed. It seems necessary, for the moment, to take into account these characteristics of the products before prescribing.

Barriers to, and Facilitators of Physical Activity in Patients Receiving Chemotherapy for Lung Cancer: An exploratory study

AIM

Physical activity (PA) has a positive effect on the cardiorespiratory fitness, lung cancer symptoms, and quality of life of lung cancer patients. The aim of our study was to identify barriers to, and facilitators of PA in lung cancer patients.

METHODS

We collected data from five patients diagnosed with primary, advanced non-small-cell lung cancer (NSCLC) who were receiving chemotherapy. Choosing a qualitative approach, we conducted an exploratory analysis using the thematic analysis technique to process the data.

RESULTS

Seven barriers to, and facilitators of PA were identified and grouped into four categories. We found that psychological and social factors affect patients' willingness and ability to engage in PA, while physiological and environmental factors have an impact on the duration, intensity, and regularity of their PA.

CONCLUSION

Our study highlighted some of the effects that the barriers to PA have on the practice of it in our patient group. Our findings may be used by professionals to design adapted PA programs.

Apoptotic markers in cultured fibroblasts correlate with brain metabolites and regional brain volume in antipsychotic-naive first-episode schizophrenia and healthy controls

Cultured fibroblasts from first-episode schizophrenia patients (FES) have shown increased susceptibility to apoptosis, which may be related to glutamate dysfunction and progressive neuroanatomical changes. Here we determine whether apoptotic markers obtained from cultured fibroblasts in FES and controls correlate with changes in brain glutamate and N-acetylaspartate (NAA) and regional brain volumes. Eleven antipsychotic-naive FES and seven age- and gender-matched controls underwent 3-Tesla magnetic resonance imaging scanning. Glutamate plus glutamine (Glx) and NAA levels were measured in the anterior cingulate (AC) and the left thalamus (LT). Hallmarks of apoptotic susceptibility (caspase-3-baseline activity, phosphatidylserine externalization and chromatin condensation) were measured in fibroblast cultures obtained from skin biopsies after inducing apoptosis with staurosporine (STS) at doses of 0.25 and 0.5 μM. Apoptotic biomarkers were correlated to brain metabolites and regional brain volume. FES and controls showed a negative correlation in the AC between Glx levels and percentages of cells with condensed chromatin (CC) after both apoptosis inductions (STS 0.5 μM: r = -0.90; P = 0.001; STS 0.25 μM: r = -0.73; P = 0.003), and between NAA and cells with CC (STS 0.5 μM induction r = -0.76; P = 0.002; STS 0.25 μM r = -0.62; P = 0.01). In addition, we found a negative correlation between percentages of cells with CC and regional brain volume in the right supratemporal cortex and post-central region (STS 0.25 and 0.5 μM; P < 0.05 family-wise error corrected (FWEc)). We reveal for the first time that peripheral markers of apoptotic susceptibility may correlate with brain metabolites, Glx and NAA, and regional brain volume in FES and controls, which is consistent with the neuroprogressive theories around the onset of the schizophrenia illness.

Significance of plankton community structure and nutrient availability for the control of dinoflagellate blooms by parasites: a modeling approach

Dinoflagellate blooms are frequently observed under temporary eutrophication of coastal waters after heavy rains. Growth of these opportunistic microalgae is believed to be promoted by sudden input of nutrients and the absence or inefficiency of their natural enemies, such as grazers and parasites. Here, numerical simulations indicate that increasing nutrient availability not only promotes the formation of dinoflagellate blooms but can also stimulate their control by protozoan parasites. Moreover, high abundance of phytoplankton other than dinoflagellate hosts might have a significant dilution effect on the control of dinoflagellate blooms by parasites, either by resource competition with dinoflagellates (thus limiting the number of hosts available for infection) or by affecting numerical-functional responses of grazers that consume free-living parasite stages. These outcomes indicate that although both dinoflagellates and their protozoan parasites are directly affected by nutrient availability, the efficacy of the parasitic control of dinoflagellate blooms under temporary eutrophication depends strongly on the structure of the plankton community as a whole.

Network analysis of gene expression in peripheral blood identifies mTOR and NF-κB pathways involved in antipsychotic-induced extrapyramidal symptoms

To identify the candidate genes for pharmacogenetic studies of antipsychotic (AP)-induced extrapyramidal symptoms (EPS), we propose a systems biology analytical approach, based on protein-protein interaction network construction and functional annotation analysis, of changes in gene expression (Human Genome U219 Array Plate) induced by treatment with risperidone or paliperidone in peripheral blood. 12 AP-naïve patients with first-episode psychosis participated in the present study. Our analysis revealed that, in response to AP treatment, constructed networks were enriched for different biological processes in patients without EPS (ubiquitination, protein folding and adenosine triphosphate (ATP) metabolism) compared with those presenting EPS (insulin receptor signaling, lipid modification, regulation of autophagy and immune response). Moreover, the observed differences also involved specific pathways, such as anaphase promoting complex /cdc20, prefoldin/CCT/triC and ATP synthesis in no-EPS patients, and mammalian target of rapamycin and NF-κB kinases in patients with EPS. Our results showing different patterns of gene expression in EPS patients, offer new and valuable markers for pharmacogenetic studies.

Amaranthaceae pollens: review of an emerging allergy in the mediterranean area

The Amaranthaceae family is composed of about 180 genera and 2500 species. These common weeds have become increasingly relevant as triggers of allergy in the last few years, as they are able to rapidly colonize salty and arid soils in extensive desert areas. The genera Chenopodium, Salsola, and Amaranthus are the major sources of pollinosis from the Amaranthaceae family in southern Europe, western United States, and semidesert areas of Saudi Arabia, Kuwait, and Iran. In Spain, Salsola kali is one of the most relevant causes of pollinosis, together with olive and grasses. To date, 9Amaranthaceae pollen allergens from Chenopodium album, Salsola kali, and Amaranthus retroflexus have been described and are listed in the International Union of Immunological Societies allergen nomenclature database.The major allergens ofAmaranthaceae pollen belong to the pectin methylesterase, Ole e 1-like, and profilin panallergen families, whereas the minor allergens belong to the cobalamin- independent methionine synthase and polcalcin panallergen families. These relevant allergens have been characterized physicochemically, and immunologically at different levels. Recombinant forms, allergenic fusion recombinant proteins, and hypoallergenic derivatives of these allergens have been expressed in bacteria and yeast and compared with their natural proteins from pollen. In this review, we provide an extensive overview ofAmaranthaceae pollen allergens, focusing on their physicochemical, and immunological properties and on their clinical significance in allergic patients. We also review studies where these recombinant allergens and their hypoallergenic derivatives have been used in clinical diagnosis and their potential use in personalized therapy.

Characterization of profilin and polcalcin panallergens from ash pollen

BACKGROUND

Ash (Fraxinus excelsior) is an important source of allergenic pollen in temperate areas of Europe. Profilin and polcalcin are 2 important panallergens involved in cross-reactivity between different sources.

OBJECTIVE

To clone and produce Fra e 2 (profilin) and Fra e 3 (polcalcin) as recombinant proteins and evaluate their immunological properties using the natural forms obtained from ash pollen.

METHODS

Total RNA from ash pollen was used as a template to obtain the specific complementary DNA (cDNA) sequences of the 2 panallergens. The cDNA-encoding sequences were cloned into the pET11b expression vector and used to transform BL21 (DE3) Escherichia coli cells. Proteins were expressed, purified by chromatography, and characterized structurally by circular dichroism, mass spectrometry, and immunologically by western blot and ELISA using profilin and polcalcin polyclonal antibodies and human sera from ash pollen-sensitized patients.

RESULTS

Profilin and polcalcin amino acid sequences from ash pollen showed a high degree of identity with homologous allergens from different sources. The cDNA-encoding allergen sequences were expressed as nonfusion recombinant proteins and purified to homogeneity. Secondary structure values were similar to those obtained from other members of these families. Allergenic properties of the recombinant allergens were observed to be equivalent to those of the natural counterparts of F excelsior pollen.

CONCLUSIONS

Fra e 2 and Fra e 3 recombinant allergens might be used in clinical diagnosis to determine profilin- and polcalcin-specific IgE levels present in the sera of ash pollen-sensitized patients, thus facilitating the finding of the sensitizing source in areas with complex sensitization profiles.

All-fiber processing of terahertz-bandwidth signals based on cascaded tapered fibers

Tapered single-mode fibers are employed to perform dynamic pulse shaping in a bandwidth of several terahertz. The transfer function of cascaded biconical tapers is controlled by introducing a phase shift into one of them through mechanical stretching. It is a simple and low-cost technique with potential to process signals with bandwidths as large as those allocated by standard optical fiber while introducing little degradation. Femtosecond pulses are shaped to prove the concept.

Intuitive pharmacogenetics: spontaneous risperidone dosage is related to CYP2D6, CYP3A5 and ABCB1 genotypes

The aim of this study is to evaluate whether the quantitative prescription of risperidone (dosage) is related to the patient's metabolic status. Metabolic status was defined in terms of the most relevant polymorphisms of CYP2D6 (*3, *4, *5, *6 and *1xN), CYP3A5 (*3A) and ABCB1 (G2677T) determined a posteriori and blinded to the clinicians. This prospective and observational study includes a cohort of 151 Caucasian psychiatric patients treated with risperidone. Significant differences (Kruskal-Wallis test p=0.01) among the doses administered were observed to correlate (Spearman's r=1, p=0.02) with the different CYP2D6 groups. Poor metabolizers received the lowest doses and ultra rapid metabolizers the highest. No significant correlations were observed with regard to CYP3A5 and ABCB1. We find that, despite not knowing patients' metabolic status, clinicians modify risperidone dosage in order to obtain the best therapeutic option.

DIEL VARIATIONS IN OPTICAL PROPERTIES OF IMANTONIA ROTUNDA (HAPTOPHYCEAE) AND THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE) EXPOSED TO DIFFERENT IRRADIANCE LEVELS(1)

Diel variations of cellular optical properties were examined for cultures of the haptophyte Imantonia rotunda N. Reynolds and the diatom Thalassiosira pseudonana (Hust.) Hasle et Heimdal grown under a 14:10 light:dark (L:D) cycle and transferred from 100 μmol photons · m(-2)  · s(-1) to higher irradiances of 250 and 500 μmol photons · m(-2)  · s(-1) . Cell volume and abundance, phytoplankton absorption coefficients, flow-cytometric light scattering and chl fluorescence, and pigment composition were measured every 2 h over a 24 h period. Results showed that cell division was more synchronous for I. rotunda than for T. pseudonana. Several variables exhibited diel variability with an amplitude >100%, notably mean cell volume for the haptophyte and photoprotective carotenoids for both species, while optical properties such as flow-cytometric scattering and chl a-specific phytoplankton absorption generally showed <50% diel variability. Increased irradiance induced changes in pigments (both species) and mean cell volume (for the diatom) and amplified diel variability for most variables. This increase in amplitude is larger for pigments (factor of 2 or more, notably for cellular photoprotective carotenoid content in I. rotunda and for photosynthetic pigments in T. pseudonana) than for optical properties (a factor of 1.5 for chl a-specific absorption, at 440 nm, in I. rotunda and a factor of 2 for the absorption cross-section and the chl a-specific scattering in T. pseudonana). Consequently, diel changes in optical properties and pigmentation associated with the L:D cycle and amplified by concurrent changes in irradiance likely contribute significantly to the variability in optical properties observed in biooptical field studies.

SIMULTANEOUS GENOTYPING OF CYP2D6*3, *4, *5 AND *6 POLYMORPHISMS IN A SPANISH POPULATION THROUGH MULTIPLEX LONG POLYMERASE CHAIN REACTION AND MINISEQUENCING MULTIPLEX SINGLE BASE EXTENSION ANALYSIS

1. The aim of the present study was to perform a descriptive study of the prevalence of the four major CYP2D6 poor metaboliser (PM) alleles (*3, *4, *5 and *6) in a Spanish population (n = 290) using a method based on a new combination of multiplex long polymerase chain reaction (PCR) and minisequencing through multiplex single base extension (SBE) analysis. 2. The method was validated using different strategies, such as allelic discrimination assay and PCR-restriction fragment length polymorphism (RFLP). 3. The allele frequencies were similar to those described for other Spanish populations, namely 0.9% (95% confidence interval (CI) 0.5-1.3), 16.4% (95% CI 14.9-18.0), 2.7% (95% CI 2.0-3.4) and 0.7% (95% CI 0.3-1.0) for the *3, *4, *5 and *6 alleles, respectively. The results were satisfactory and left little doubt as to the genotypes, which were confirmed either by allelic discrimination assay (*4 and *6) or PCR-RFLP (*3) with 100% concordance. 4. The present study corroborates the low prevalence of the most frequent polymorphism (CYP2D6*4) that leads to null CYP2D6 activity in Spain and the allelic geographical gradient between Caucasian populations in the north and south. The present study reports a technique for the detection of four polymorphisms that account for 98% of the CYP2D6 defect alleles. This multiplex long PCR-SBE technique is a combination of several known methods to genotype CYP2D6 alleles (*3, *4, *5 and*6). Given the importance of CYP2D6 in drug metabolism and the need to genotype a large number of samples, we believe that this method will find broad application.

[Prognostic estimation in critical patients. Validation of a new and very simple system of prognostic estimation of survival in an intensive care unit]

OBJECTIVE

To make the validation of a new system of prognostic estimation of survival in critical patients (EPEC) seen in a multidisciplinar Intensive care unit (ICU).

DESIGN AND SCOPE

Prospective analysis of a patient cohort seen in the ICU of a multidisciplinar Intensive Medicine Service of a reference teaching hospital with 19 beds.

PATIENTS AND METHOD

Four hundred eighty four patients admitted consecutively over 6 months in 2003. Data collection of a basic minimum data set that includes patient identification data (gender, age), reason for admission and their origin, prognostic estimation of survival by EPEC, MPM II 0 and SAPS II (the latter two considered as gold standard). Mortality was evaluated on hospital discharge. EPEC validation was done with analysis of its discriminating capacity (ROC curve), calibration of its prognostic capacity (Hosmer Lemeshow C test), resolution of the 2 x 2 Contingency tables around different probability values (20, 50, 70 and mean value of prognostic estimation). The standardized mortality rate (SMR) for each one of the methods was calculated. Linear regression of the EPEC regarding the MPM II 0 and SAPS II was established and concordance analyses were done (Bland-Altman test) of the prediction of mortality by the three systems.

RESULTS

In spite of an apparently good linear correlation, similar accuracy of prediction and discrimination capacity, EPEC is not well-calibrated (no likelihood of death greater than 50%) and the concordance analyses show that more than 10% of the pairs were outside the 95% confidence interval.

CONCLUSION

In spite of its ease of application and calculation and of incorporating delay of admission in ICU as a variable, EPEC does not offer any predictive advantage on MPM II 0 or SAPS II, and its predictions adapt to reality worse.

Concentration of hydroxyproline in blood: a biological marker in occupational exposure to asbestos and its relationship with Pi*Z and Pi*S polymorphism in the alpha-1 antitrypsin gene

BACKGROUND

Hydroxyproline (OHP) is one of the most abundant amino acids in collagen and, in general, it provides a good measure of overall collagen catabolism.

METHODS

Asbestos workers suffering from asbestosis (cases n = 85); asbestos exposed workers without asbestosis (exposed controls, EC, n = 86), and non-exposed population (non-exposed controls, NEC, n = 122) were studied. The concentration of free OHP in whole blood was measured following the Pico-Tag procedure.

RESULTS

Concentration of OHP in blood was significantly different in the three groups studied (P < 0.001), being higher in cases (19.8 +/- 14.7 micromol/L) than in EC (16 +/- 12.4) and NEC (13.5 +/- 6.7). When all individuals were grouped and stratified by the Pi*S and Pi*Z polymorphisms in the alpha-1-antitrypsin gene, the highest OHP levels were detected in the Pi*S homozygotes, one of the asbestosis-at risk-genotypes (Pi*S homozygotes, x = 24.5 +/- 11.7; Pi*S heterozygotes, x = 16.6 +/- 10.0; wild type, wt, x = 15.9 +/- 11.8).

CONCLUSIONS

Blood OHP concentration could be used for monitoring human exposure to asbestos, either as a marker for occupational monitoring or as an additional clinical parameter in diagnostic exploration of asbestosis.

Pi*S and Pi*Z alpha 1 antitrypsin polymorphism and the risk for asbestosis in occupational exposure to asbestos

Alpha 1 antitrypsin is a highly polymorphic anti-elastase enzyme, especially active in the protection of alveoli and liver. Here we studied the distribution of two deficient alleles Pi*Z and Pi* S, in 194 asbestos workers, of whom 100 were asbestosis cases, and 94 were controls without disease (exposed controls, EC). A second group of controls without asbestos exposure (non-exposed controls, NEC; n=122) was also included. Multivariate analysis adjusted by age and smoking habit showed ninefold risk for asbestosis in Pi*Z heterozygous individuals and 5.9-fold risk for Pi*S homozygous although differences were only significant in the first case (cases vs. EC: OR 8.9; p=0.04). Considering both genotypes (Pi*Z heterozygous, Pi*S homozygous) we obtained an OR of 8 (p=0.01). Our results suggest that the alpha 1 antitrypsin polymorphisms, especially Pi*Z, could help to predict asbestosis risk and confirm the high prevalence of the Pi*S allele in Spain.

Glutathione S-transferase (GSTM1 and GSTT1)-dependent risk for colorectal cancer

BACKGROUND

The deleted GSTT1 and GSTM1 genotypes (null genotypes) resulting in loss of transferase activity are found in 10-20% and 50-60% of the population, respectively.

PATIENTS AND METHODS

The GSTT1- and GSTM1-dependent risk for sporadic colorectal cancer (CRC) was studied in 247 incident CRC cases and 296 hospital-based controls.

RESULTS

The GSTT1-null genotype was found to be 1.5 times more prevalent in CRC patients (17.4%) compared with controls (11.1%) (crude OR 1.6; p = 0.03). The GSTM1-null genotype was found to be equally prevalent in cases and controls (53%). Multivariate analysis showed a significant 1.7-fold risk for CRC associated with the GSTT1-null genotypes (p = 0.04) and this increased to 2.9 for smokers (p = 0.02).

CONCLUSION

This study provides evidence of gene-environment interaction and illustrates the importance of further research into the role of genetic susceptibility for CRC.

Serine 132 is the C3 covalent attachment point on the CH1 domain of human IgG1

The covalent binding of C3 (complement component C3) to antigen-antibody complexes (Ag.Ab; immune complexes (ICs)) is a key event in the uptake, transport, presentation, and elimination of Ag in the form of Ag.Ab.C3b (IC.C3b). Upon interaction of C3 with IgG.IC, C3b.C3b.IgG covalent complexes are formed that are detected on SDS-polyacrylamide gel electrophoresis by two bands corresponding to C3b.C3b (band A) and C3b.IgG (band B) covalent complexes. This allows one to evaluate the covalent binding of C3b to IgG antibodies. It has been described that C3b can attach to both the Fab (on the CH1 domain) and the Fc regions of IgG. Here the covalent interaction of C3b to the CH1 domain, a region previously described spanning residues 125-147, has been studied. This region of the CH1 domain is exposed to solvent and contains a cluster of six potential acceptor sites for ester bond formation with C3b (four Ser and two Thr). A set of 10 mutant Abs were generated with the putative acceptor residues substituted by Ala, and we studied their covalent interaction with C3b. Single (Ser-131, Ser-132, Ser-134, Thr-135, Ser-136, and Thr-139), double (positions 131-132), and multiple (positions 134-135-136, 131-132-134-135-136, and 131-132-134-135-136-139) mutants were produced. None of the mutants (single, double, or multiple) abolished completely the ability of IgG to bind C3b, indicating the presence of C3b binding regions other than in the CH1 domain. However, all mutant Abs, in which serine at position 132 was replaced by Ala, showed a significant decrease in the ability to form C3b.IgG covalent complexes, whereas the remaining mutants had normal activity. In addition we examined ICs using the F(ab')2 fragment of the mutant Abs, and only those containing Ala at position 132 (instead of Ser) failed to bind C3b. Thus Ser-132 is the binding site for C3b on the CH1 domain of the heavy chain, in the Fab region of human IgG.