The rhizosphere supports the development and activity of a huge and diversified microbial community, including microorganisms capable to promote plant growth. Among the latter, plant growth-promoting rhizobacteria (PGPR) colonize roots of monocots and dicots, and enhance plant growth by direct and indirect mechanisms. Modification of root system architecture by PGPR implicates the production of phytohormones and other signals that lead, mostly, to enhanced lateral root branching and development of root hairs. PGPR also modify root functioning, improve plant nutrition and influence the physiology of the whole plant. Recent results provided first clues as to how PGPR signals could trigger these plant responses. Whether local and/or systemic, the plant molecular pathways involved remain often unknown. From an ecological point of view, it emerged that PGPR form coherent functional groups, whose rhizosphere ecology is influenced by a myriad of abiotic and biotic factors in natural and agricultural soils, and these factors can in turn modulate PGPR effects on roots. In this paper, we address novel knowledge and gaps on PGPR modes of action and signals, and highlight recent progress on the links between plant morphological and physiological effects induced by PGPR. We also show the importance of taking into account the size, diversity, and gene expression patterns of PGPR assemblages in the rhizosphere to better understand their impact on plant growth and functioning. Integrating mechanistic and ecological knowledge on PGPR populations in soil will be a prerequisite to develop novel management strategies for sustainable agriculture. Photosynthetic terrestrial plants play key roles as ecosystem engineers . They co10 bacteria per gram of soil  and signals that attract microbial populations, especially those able to metabolize plant-exuded compounds and proliferate in this microbial habitat . Root ex of soil  and enco of soil . The cor of soil . Its com of soil . Since r of soil . Plant-d of soil .sine qua non for plant growth promotion .Most terrestrial plants develop their root system to explore soil and find nutrients to sustain growth. Root is a complex organ made of distinct regions such as the root tip, root meristem, differentiation and elongation zones, and emerging lateral roots . These rChanges in RSA may result from interferences of PGPR with the main hormonal pathways involved in regulating plant root development: auxin, cytokinin, ethylene, and to a lesser extend gibberellin, and abscisic acid (ABA) . The balFigure 1; ipdC/ppdC bacterial gene) is a key enzyme involved in the indolepyruvic acid pathway. Effects of ipdC mutants on plant root morphology are often altered in comparison to those of wild-type strains , and nitric oxide (NO). Indole-3-acetic acid (IAA) is the best-characterized auxin produced by many plant-associated bacteria, including PGPR . Exogeno strains .Azospirillum brasilense have a nitrite reductase activity and consequently are able to produce NO during root colonization . GUS staining appeared more intense on a wider region of the root tip as well as in the vasculature, suggesting that there was a change of auxin distribution in the root in response to STM196 inoculation, even though this strain is a low auxin producer  has been documented in various PGPR like polymyxa . Cytokinpolymyxa . Inoculapolymyxa . Bacterianalyses . ConsequAzospirillum brasilense  coding for an ACC deaminase, which degrades ACC into ammonium and α-ketobutyrate . Through the analysis of the infrared spectral characteristics of crude cell wall preparations of maize roots, Azospirillum lipoferum CRT1 had lower lignin content than uninoculated ones. This result contrasts with those aforementioned for biocontrol agents. Nevertheless, lower lignin content may facilitate cell elongation, and therefore overall root elongation. Similarly, Azospirillum irakense produces pectate lyases that are capable of degrading the pectate content of root cell wall and might allow its progression between root cortex cells and its functioning as an endophyte , and provide clues to understand the systemic effect of PGPR.In addition to their effects on root tissues, PGPR can modify the physiology and functioning of plant tissues located at a substantial distance from the colonized sites, such as shoots. Two types of mechanisms are involved. On the one hand, some PGPR can enhance nutrient availability/uptake for plant roots. Stimulation of plant nutrition will lead to modifications in primary metabolism and consequently will contribute to enhance growth. On the other hand, certain PGPR trigger specific systemic responses, mostly by unknown signaling mechanisms. High-throughput analyses of plant transcriptomic and metabolomic responses have evidenced the effects of PGPR on plant gene expression and metabolite accumulation, respectively. These results highlight the extensive effect of PGPR on whole plant physiology and functioning .The impact of PGPR on plant nutrition may result from effects on plant nutrient uptake and/or on plant growth rate . It is iPseudomonas, Bacillus, Rhizobium – are able to dissolve insoluble forms of phosphate  in leaves of Arabidopsis; upregulated genes were involved in maintenance of genome integrity, growth hormone and amino acid syntheses, ABA signaling and ethylene suppression, Ca2+ dependent signaling and induction of ISR . Some studies have shown that PGPR can elicit changes in the activities of root enzymes involved in the production of metabolites, especially flavonoids, leading to changes in the pattern of root exudation  in barley and wheat roots was increased when a rhizosphere bacterium was applied with the fungus  and biotic factors  that can lead to distinct expression patterns in space and time, possibly with different effects on host plant . In thisphlA, involved in DAPG biosynthesis, in Pseudomonas protegens (formely Pseudomonas fluorescens) CHA0 (phlA was increased fourfold in the rhizosphere of monocots (maize and wheat) compared to the rhizosphere of dicots (bean and cucumber). The analysis of six maize cultivars also revealed that phl expression and hence biocontrol activity could be affected by plant genotype  CHA0 . The expgenotype . Specifigenotype . Among 6ens CHA0 . No specpression . Umbellipression  whereas pression .acdS) is another bacterial function that may be differentially expressed according to plant genotypes. Indeed, in vitro experiments demonstrated that some compounds present in root exudates tightly control acdS expression. First, ACC, the precursor of ethylene that is metabolized by AcdS, can positively regulate acdS expression  indicated that this amino acid is abundant at the emergence of secondary roots  signals that allow bacteria to monitor their density and to coordinate gene expression only when a quorum of cells is achieved  and otheN-acyl-homoserine lactones (AHLs). In fluorescent pseudomonads, colonization properties and biosynthesis of antimicrobial metabolites, such as phenazines, is often subjected to an AHL-based QS regulation  but no effect is observed on cellulase activity and on the phytostimulatory effect , whereas others can intercept AHL or can act as a physical barrier preventing their diffusion  were upregulated on roots in the presence of Pseudomonas fluorescens F113 compared with its DAPG-negative mutant  and one mycorrhizal strain (Rhizophagus irregularis/Glomus intraradices JJ291) showed an increase of root surface, root volume and number of roots, although data were not statistically significant compared to the single Rhizophagus inoculation (Azospirillum strains were tested) could lead to significant modification of maize growth . When analysing plant growth-promoting effects, it is thus important to integrate the complexity of the interactions between PGPR populations within the rhizo-microbiome. To do so, functional ecology approaches are needed, in which the relations between the size, diversity and activities of PGPR assemblages in the rhizosphere are taken into account. This is of particular importance when assessing the effect of various environmental factors, including that of plant genotype.Many studies have deciphered the mechanisms of action of PGPR using one individual strain and one host plant. But in reality, as described above, PGPR strains are not acting individually in the rhizosphere but rather as part of bacterial communities, in which cell communication signals may coordinate the activities of all individual strains. Indeed, a vast array of PGPR populations displaying co-occurring plant-beneficial activities and that may share between each other antagonistic or synergistic effects are interacting with a same host plant , integrating competitive and inhibitory effects , both at plant species . Next-generation sequencing technologies have started to reveal their taxonomic and functional diversity. They have begun to bring new knowledge on the ecology of PGPR functional groups. In the near future, it is expected that metatranscriptomics and metaproteomics will develop drastically, and will allow further progress on the understanding of the activity and ecological behavior of natural PGPR populations within the rhizosphere. However, given the heterogeneity in space and time of the rhizosphere habitat, samplings at different times and locations within the plant rhizosphere and within fields will be essential to better understand the ecology and performance of PGPR at plant and field plot scales. Nevertheless, despite being very reductionist, mechanistic functional studies using one PGPR and one plant are still useful to investigate the ways PGPR exert beneficial effects on plants. We think that the most important advances on plant-PGPR cooperation will be brought in the future by combining both ecology and functional biology approaches.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Low birth weight has been associated with reduced hand grip strength, which is a marker of future physical function and disease risk. The aim of this study was to apply a twin pair approach, using both ‘individual’ data and ‘within-pair’ differences, to investigate the influence of birth weight on hand grip strength and whether this association may be mediated through fat free mass (FFM). Participants from the East Flanders Prospective Twin Survey were included if born without congenital abnormalities, birth weight >500 g and ≥22 weeks of gestation. Follow up in adulthood (age: 18–34 year), included anthropometric measures and hand grip . Birth weight was positively associated with hand grip strength  and FFM , adjusted for gestational age, sex and adult age. Using ‘within-pair’ analyses, the birth weight hand grip association was significant in DZ men only , which was attenuated following adjustment for FFM. Within-pair birth weight FFM associations were most pronounced in DZ men . Our ‘individual’ analyses show that higher birth weight is associated with greater adult hand grip strength, which is mediated through greater adult FFM. The ‘within-pair’ analyses confirm this observation and furthermore show that, particularly in men, genetic factors may in part explain this association, as birth weight differences in DZ men result in greater differences in adult strength and FFM. The association between low birth weight and increased disease risk in later life is well established Birth weight is used as a measure of prenatal growth, which is not only determined by the prenatal environment, but also by the foetus' genetic potential. As a consequence, associations between birth weight and adult disease may be due to a compromised environment in utero, or to genetic factors that affect both birth weight and adult disease risk. For example, it has been suggested that the previously observed association between low birth weight and increased risk of type 2 diabetes Twin studies provide a unique opportunity to disentangle the contribution of foetal growth restriction, maternal environment and genetic factors to the birth weight – adult disease association. This is because both members of a twin pair have the same gestational age and also share the same maternal exposures during pregnancy, such as maternal weight, nutrition and smoking status. However, each individual within a twin pair will have their own foetal-placental environment, which will contribute to differences in birth weight between the two twins. In monozygotic (MZ) twins, these differences in birth weight are solely due to the foetal-placental environment, whereas in dizygotic (DZ) twins differences in birth weight may also be due to genetic as well as environmental differences The aim of this study was therefore to investigate the influence of birth weight on hand grip strength in young adult twins. As it has been hypothesised that the association between birth weight and hand grip may be mediated through fat free mass The study was approved by the Ethics Committee of the Faculty of Medicine of the Katholieke Universiteit, Leuven, Belgium, and all participants gave written informed consent.The East Flanders Prospective Twin Survey (EFPTS) is a population-based twin survey that prospectively registered all twins born in the Belgian Province of East Flanders since 1964 We randomly contacted 803 pairs of all twins born between July 1964 and May 1982 during adulthood, when aged between 18 and 34 years, to participate in the Prenatal Programming Twin Study. Of those, 424 pairs  agreed to participate For the within-pair analyses, we excluded opposite-sex twin pairs (n = 43 twin pairs), as including pairs with discordant sex, where sex may be associated with both birth weight and hand grip, can lead to an overestimation of effect sizes. Pairs of which only one member participated in the study were also excluded, leaving a total of 326 same-sex twin pairs, 170 female pairs  and 156 male pairs .2 (m2). Fat free mass (kg) was estimated using bioelectrical impedance .Height was measured barefoot to the nearest 0.1 cm using a wall mounted stadiometer (Harpenden). Weight was measured to the nearest 0.1 kg on a balance scale  with the volunteer wearing light clothing. Body mass index (BMI) was calculated as weight (kg)/heightHand grip strength of the dominant hand was measured once using a Jamar hand grip dynamometer . Measurements were performed whilst standing, with the arm fully extended next to the body. Hand grip strength was measured on a single occasion after a demonstration and clear explanation by the research associate. Participants were able to familiarise themselves with the hand dynamometer prior to this measurement, without carrying out the test. Once the participants felt ready to carry out the test, they were verbally encouraged by the research associate to perform to their maximum ability.Mean and standard deviation were calculated for descriptive characteristics, for all individuals, for variables collected at birth as well as in adulthood. T-tests were used to investigate differences in means between MZ and DZ twins and between men and women.Twins were considered as individuals , to allow comparisons with other cohort studies, and as members of twin pairs .Linear regression was performed using mixed effect models, allowing for the fact that twins share more similarities than unrelated individuals, to investigate the associations between birth weight and adult hand grip strength. Similarly, the association between birth weight and adult fat free mass were analysed using linear regression mixed effect models.Regression models were adjusted for gestational age, adult age and where analysis was carried out in both men and women together the models were adjusted for sex. To investigate whether associations were independent of adult body size, models were additionally adjusted for adult height. Models investigating associations between birth weight and adult hand grip were also adjusted for adult fat free mass to examine whether associations were independent of fat free mass.Evidence for different effects in men and women were investigated by including an interaction term between birth weight and sex.difference in birth weight between the first and second born twin is modelled as the ‘exposure’ and the difference in hand grip between the first and second born twin is modelled as the ‘outcome’. This allows the influence of birth weight on hand grip strength to be estimated independently from shared maternal influences, such as maternal weight, nutrition and smoking status, and in MZ twins additionally from genetic factors.The Furthermore, comparing the effect size of the within-pair association of MZ twins to those of DZ provides information on the contribution of genetic factors to the birth weight – adult had grip strength relationship. For example, as MZ twin pairs share the same genes, any observed within-pair associations between birth weight and adult hand grip strength are more likely to be due to foetal-placental or environmental influences. Whereas larger effect sizes in DZ twin pairs, compared to MZ twins, would suggest that genetic factors contribute to the association between birth weight and adult hand grip strength.The associations between within-pair differences in exposure and outcome were analysed using linear regression. The first regression model was presented as unadjusted, or adjusted for sex where analysis was carried out in men and women together. The second regression model included adjustment for the within-pair difference in adult height, to investigate the influence of body size. Finally, hand grip models were also repeated adjusting for sex, within-pair difference in adult height and within-pair difference in adult fat-free mass, to investigate whether these associations were independent of body size and composition.All analyses were performed using Stata 9 .Female twins were just over 106 grams lighter at birth (p = 0.002) and had lower adult hand grip strength  than male twins Table 1.Birth weight was positively associated with hand grip strength  with a 1 kg increase in birth weight corresponding to a 2.6 kg increase in adult hand grip strength after adjustment for gestational age, adult age and sex Table 2.Additional adjustment for adult height attenuated the strength of association by more than half but remained significant . After adjustment for fat free mass the association was further attenuated and no longer significant Table 2.The strength of association between birth weight and adult hand grip strength in men was more than twice that of women, after adjustment for gestational age and adult age Table 2.We found that higher birth weight was consistently associated with increased fat free mass  and the strength of this association was more than halved after further adjustment for adult height . The association was twice as large in men  than in women  when adjusted for gestational age and adult age. Yet, the sex interaction was not significant . Adjustment for height attenuated the association, more so in women than in men .The association between within-pair difference in birth weight and the within-pair difference in adult hand grip strength was positive in direction but not significant , suggesting that, within a pair, the twin with the higher birth weight tended to have greater adult handgrip strength than their lighter sibling. When stratifying by sex, again there was a positive trend, but this was not statistically significant in either men or women. Further adjustment for intra-pair difference in either height or fat free mass completely abolished the association Table 3., When stratifying by zygosity status, to investigate the influence of genetic factors, we found a strong association between the within-pair difference in birth weight and the within-pair difference in adult hand grip in DZ men, while no association was observed in MZ men , Table 4Consistent with the cohort analyses, we observed a positive association between the within-pair difference in birth weight and the within-pair difference in fat free mass, indicating that the higher birth weight twin had more fat free mass in adult life compared to their lower birth weight twin. Again, this association was more pronounced in men than in women. Adjustment for height attenuated the association in men, and completely abolished the association in women.Positive associations between the within-pair difference in birth weight and the within-pair difference in adult fat free mass were observed in both DZ and MZ men, but this association was of a more than 4-fold greater magnitude in DZ men compared to MZ men Table 4 The opposite patterns of association were observed in women, as an association between the within-pair difference in birth weight and the within-pair difference in fat free mass, was only observed in MZ women but not in DZ women Table 4,Our cohort analyses that consider twins as individuals show that a higher birth weight is associated with greater adult hand grip strength, which is predominantly mediated through the association between birth weight and fat free mass. The overall trend from the twin pair analyses, which controls for shared factors, confirms the cohort observations and suggests that within a pair the heavier twin at birth has greater hand grip strength in adult life than their lighter sibling. Uniquely, the twin pair analysis identified that the association between birth weight and hand grip strength was stronger in DZ than in MZ men, suggesting a potential influence of genetic factors, acting on both on birth weight and adult hand grip in men.The positive associations between birth weight and adult hand grip strength are consistent with those observed in singletons and show similar effect sizes Our findings suggest different patterns in the association and mediation between birth weight, and hand grip and fat free mass for men and women. In women the association between birth weight and hand grip strength was completely abolished after adjustment for adult height or fat free mass. In addition the association between birth weight and adult fat free mass in women was substantially reduced after adjustment for adult height. In men, however, while the association with hand grip is attenuated after adjustment for adult height or fat free mass, there remains a residual effect of birth weight on adult fat free mass independent of adult height. This suggests that the association between birth weight and grip strength is mediated through both adult height and fat free mass in women, whereas in men the association is largely mediated through fat free mass.2) in boys The gender-specific association between birth weight and adult fat free mass is consistent with the results observed in a study in children that used the more sensitive four-compartment measurement of body composition. In this study, birth weight was associated with height in both boys and girls, but birth weight was only associated with fat free mass (measured as Fat Free Mass Index = FFM/heightA potential explanation for the difference observed in the birth weight fat free mass association observed in this study, which was only independent of height in men, is that adult muscle mass distribution is known to vary between men and women both birth weight and adult hand grip. A similar pattern is observed for fat free mass; i.e. in the association was more pronounced in DZ men than in MZ men, again suggesting that while in utero growth restriction influences adult fat free mass, there are additional genetic factors acting on both birth weight and later fat free mass.A novel finding in this study was the significant association, using within-pair analysis, between birth weight and adult hand grip strength in DZ but not in MZ men. This suggests that, at least in men, the association between birth weight and adult grip strength may in part be explained by genetic influences that act on difference in birth weight between the first and second born twin. The range of such within-pair differences are typically much smaller than the range of birth weights observed for individuals using conventional cohort analysis, making it harder to detect associations, so it is possible that the within-pair analysis was underpowered. Furthermore, it should be noted that this present study used bio-electrical impedance to estimate fat-free mass, which may not be as accurate as other laboratory based measures such as duel x-ray absorbtometry, densitometry or deuterium dilution, although many of these more detailed measures are less feasible in larger studies. It should also be noted that we did not measure physical activity, which can influence both fat-free mass and physical performance. Therefore, it is possible that the associations between birth weight and fat-free mass may be mediated by physical activity levels. Finally, we acknowledge that twins may not be representative of singletons, as twins tend to be born both earlier and lighter. Therefore, the results should be interpreted with caution. However, we should highlight that our twin sample is randomly drawn from a prospective, population-based cohort with detailed information collected at birth and with objective measures of muscle strength and body composition in young adulthood.There are however some limitations to this present study. While the twin pair analysis has a number of advantages for disentangling genetic and in utero effects, it has typically less statistical power to detect associations as compared to the individual cohort analyses. Firstly, because using twin pairs as the unit of analysis effectively halves the sample size, secondly the within-pair analysis uses the Future large scale twin studies would be particularly useful to investigate the developmental origins of physical performance and body composition further. Elucidating the influences of shared maternal factors, both in terms of biological influences such as maternal weight and nutrition status, as well as confounding from socio-economic factors, is one of the key issues when investigating the developmental origins of health and disease. Therefore, future twin studies with detailed maternal measures of these variables would be particularly useful.Future genome wide association studies may identify common genetic variants influencing birth weight, muscle strength and body composition. For preventive purposes, it would be particularly interesting to understand whether the associations between these potential gene variants with future body composition and physical function, including muscle strength, are modified by lifestyle factors, such as increased physical activity.In summary, our findings suggest that birth weight is positively associated with adult hand grip strength, which appears to be mediated predominantly via influences of birth weight on fat free mass. Furthermore, in men these associations may, at least in part, be influenced by genetic factors that act on both birth weight and later hand grip strength and fat free mass. These findings suggest that a compromised early life, due to either growth restriction in utero or other maternal factors, may be important for both hand grip strength and fat free mass in adulthood, which has implications for both physical function and disease risk in later life.


There is evidence from two meta-analyses that children born through caesarean section (C-section) may have an increased risk of developing asthma compared with those born through vaginal delivery.To evaluate the association between mode of delivery and wheezing (current and persistent) in childhood and adolescence, in two birth cohort studies in Brazil.The outcome variable was based on the International Study of Allergy and Asthma questionnaire, which collects information about wheezing within the 12 months before the interview. Persistent wheezing was defined when it was present in more than one follow-up at different ages, in the 1993 cohort. The questions were asked to mothers when children were aged 4 years (1993 and 2004 cohorts) and directly to cohort participants at 11 and 15 years (1993 cohort). Mode of delivery was collected by the research team of each cohort when children were born.Response rates in the last follow-up visit of the 1993 and 2004 cohorts were 85% and 92%, respectively. The prevalence of current wheezing increased from 20% to 28% at 4 years from 1993 to 2004; at 11 and 15 years, the prevalence was around 14% and 12%, in the 1993 cohort. The proportion of C-sections increased from 30.5% to 45% between 1993 and 2004. In each cohort, the prevalence of current wheezing was similar among children born through vaginal and C-section. The risk for persistent wheezing in the 1993 cohort was higher among girls born through C-section than boys.Despite the increase in the proportion of C-section in two cohorts in Southern Brazil, we found no evidence of an association between mode of delivery and the subsequent risk of wheezing. Among girls, although there was no statistical significance, the risk was higher for those born by C-section, especially regarding persistent wheezing. Caesarean sections (C-sections) are estimated to be required in 5–15% of all deliveries . Lack ofThere is evidence from two meta-analyses , 5 that In Pelotas, a southern Brazilian city, an epidemic of C-sections was reported some years ago , 7, and The aim of the present study was to evaluate the association between mode of delivery and current wheezing or persistent wheezing in childhood and adolescence in two birth cohort studies in Brazil. Our original hypothesis was that individuals born through C-section would be at greater risk of wheezing in comparison with those born through vaginal delivery.Pelotas is a 340 000 inhabitant city located in the extreme south of Brazil. Two birth cohort studies were launched in the city within the interval of 11 years , 9. The The outcome variable current wheezing was defined based on the International Study of Allergy and Asthma (ISAAC) questionnaire –12, whicConfounding variables were defined on the basis of the current literature on the association between mode of delivery and current and persistent wheezing , 13–21. Child variables: Birth weight (measured by the research team at the time of delivery), sex, gestational age (based on the date of the last period), intrauterine growth restriction  [ curves) , skin coMaternal variables: Age and education at the time of delivery, smoking during pregnancy , smoking at the age of follow-up  and current wheezing (self-report).Paternal variables: Smoking at the age of follow-up and current wheezing (self-report). These variables were collected for the person living with the mother, regardless of being the natural father of the cohort member or not.Family variables: Socio-economic position was based on the possession of different household assets. Continuous variables were created using principal component analyses. This variable was collected at birth, and divided into tertiles for stratified analyses.Initial statistical analyses included the calculation of the prevalence and respective 95% confidence intervals (CI) of current wheezing according to type of delivery. Later, the odds ratios (ORs) were calculated in a logistic regression adjusted for confounding variables, using the statistical package Stata version 9.2 .In all analyses, the vaginal mode of delivery was set as the reference category. The visit at 4 years of age of the 1993 cohort was weighed given the oversampling of low birth weight children , and tesThe Federal University of Pelotas Medical School Ethics Committee approved all phases of each cohort. Informed consent was obtained from parents.Response rates in the last follow-up visit of the 1993 and 2004 cohorts were, respectively, 85% and 92%. In The proportion of C-sections increased from 30.5% to 45% between 1993 and 2004. Mean birth weight was stable over time. Mean gestational age was slightly reduced, as well as the proportion of intrauterine growth restriction. Mean maternal age remained almost the same over time, and maternal schooling increased considerably in the 11-year period. Maternal smoking during pregnancy decreased from 33.3% to 27.2%, whereas maternal current wheezing increased from 15.7% to 20.8%, as is shown in P-value (0.06).The same was observed for socio-economic position , i.e. noUsing data from two population-based cohorts in southern Brazil, we found no evidence of a significant association between mode of delivery and the subsequent risk of wheezing. This relationship has been debated over the last years. Most original studies available found non-significant results, or slightly higher risk of asthma among those born through C-sections compared with those born by vaginal delivery –21. DataThere is a biological plausibility for an association between mode of delivery and asthma, because the development of the immune system may differ according to the type of delivery. Special attention has been paid to the production of types 1 and 2 T-helper cytokines . HoweverSome methodological issues need to be highlighted. First, we rely on prospective data of two well-known population-based birth cohort studies , 9. SecoWe also would like to point out some limitations of our study. We do not know whether C-sections in these two Brazilian cohorts were carried out by ‘doctor indication’ or due to other factors, such as doctor or patients convenience; it appears to us that the great majority of C-sections in our place are not a well-defined medical indication and most of these C-sections occur among rich families. This is relevant because in one of the meta-analyses the association between C-section and asthma decreased and was no longer significant when exposure was defined as birth by an ‘uncontaminated’ C-section  . We wereIt could be argued that statistical power was also a limitation of our study. It was not possible to analyse persistent wheezing at the age of 4, 11 and 15 years old for the 1993 cohort stratified by sex and particularly by socio-economic position; the sample size was not enough for this analyses. We decided to maintain the stratification by sex due to the fact that the association found by Renz-Polster was gender specific, with a positive association only among girls  and not among boys  [In conclusion, some findings of the present study were very similar to those presented in two recent meta-analyses , 13. ForA point to be highlighted in our study is that, regardless of the similar assessment of current wheezing across all ages, there was a lack of pattern in our results. For example, sometimes the OR of current wheezing among those born through C-section was higher than the unity, indicating an increased risk, but in other cases it was lower than the unity, indicating a decreased risk. This might suggest that the association between current wheezing and mode of delivery is not evident in Brazil. On the other hand, it appears that severe wheezing such as persistent wheezing, and particular among girls may be associated with C-sections. Other studies in developing countries are needed to confirm our findings.


Head circumference (HC) reflect growth and development of the brain in early childhood. It is unknown whether socioeconomic differences in HC are present in early childhood. Therefore, we investigated the association between socioeconomic position (SEP) and HC in early childhood, and potential underlying factors.The study focused on Dutch children born between April 2002 and January 2006 who participated in The Generation R Study, a population-based prospective cohort study in Rotterdam, the Netherlands. Maternal educational level was used as indicator of SEP. HC measures were concentrated around 1, 3, 6 and 11 months. Associations and explanatory factors were investigated using linear regression analysis, adjusted for potential mediators.The study included 3383 children. At 1, 3 and 6 months of age, children of mothers with a low education had a smaller HC than those with a high education . Child’s length and weight could only partially explain the smaller HC at 1 and 3 months of age. At 6 months, birth weight, gestational age and parental height explained the HC differences. At 11 months, no HC differences were found.Educational inequalities in HC in the first 6 months of life can be mainly explained by pregnancy-related factors, such as birth weight and gestational age. These findings further support public health policies to prevent negative birth outcomes in lower socioeconomic groups. Growth in childhood is an important indicator of children’s health Several studies recognized head circumference (HC) as an important reflection of growth and development of the brain, especially in early childhood The effect of SEP on growth of HC has been previously described This study was embedded within the Generation R Study, a population-based prospective cohort study from fetal life until young adulthood that has previously been described in detail Consent of postnatal follow-up was available for 7893 children. We restricted our analyses to the subgroup of children of Dutch ethnicity, because SEP may interact with ethnicity regarding their effects on growth and health Level of maternal education was established using questionnaires at enrollment. The Dutch Standard Classification of Education was used to categorize 4 subsequent levels of education: 1. high (university degree), 2. mid-high , 3. mid-low  and 4. low  HC measurements were taken during routine screenings at 1, 2, 3, 4, 6 and 11 months by well-trained staff. HC was measured to the nearest 0.1 cm by a tape line. Values were expressed as age- and gender-adjusted standard-deviation scores (SDS) using Dutch reference growth curves Any effect of maternal educational level on child’s HC is probably an indirect one, acting through more proximal determinants of early growth, so-called mediators Birth weight and gestational age at birth were obtained from midwife and hospital registries. We used gestational-age adjusted standard deviation scores for birth weight.Gestational diabetes was diagnosed according to Dutch midwifery and obstetric guidelines using the following criteria: random glucose level >11.0 mmol/L, fasting glucose >7.0 mmol/l or a fasting glucose between 6.1 and 6.9 mmol/L with a subsequent abnormal glucose tolerance test, in women with no pre-existing diabetes.Information about smoking and alcohol consumption was assessed in first, second and third trimester. Smoking and alcohol use at enrollment were assessed by a single closed question with three answer options . To assess smoking in second and third trimester, mothers were asked whether they smoked in the past 2 months  in the second and third questionnaire.2), we calculated pre-pregnancy body mass index (BMI).Maternal and paternal heights were measured at our research centers. Pre-pregnancy weight was established at enrollment through questionnaire. On the basis of height and pre-pregnancy weight  and the presence of financial difficulties (yes/no).Because HC, length and weight are related to each other, we evaluated the contribution of the children’s weight and length at time of HC measurement We treated maternal age at enrollment and parity as potential confounders, since they cannot be considered indisputable mediators model 1– B model 1 with mediator)/(B model 1)) , 3 (mid-90% range 3.0–3.8), 6 (mid-90% range 5.8–6.9) and 11 (mid-90% range 10.4–11.9) months of age using multiple linear regression. Unstandardized regression coefficients, reflecting the difference in HC (in SDS), and 95% confidence intervals (CI) were reported for each educational level compared to the reference category . We started with a model that included the confounders (model 1). Next, this model was additionally adjusted for the potential mediators. For each adjustment, the corresponding percentages of change in HC differences (effect estimates) were calculated by comparing the HC differences of model 1 with the adjusted ones (100 x (B odel 1))  [33]. On0+ ß1 * educational level + ß2 * age + ß3* educational level * age. In this model the interaction term educational level * age was added with a significance of p<0.001. Age reflects the time of HC measurement.Linear mixed models (‘PROC MIXED’ procedure in SAS) were used to assess the association between maternal educational level and longitudinally measured SD scores of HC in the first year of life. In total, we had 16958 measurements of SD scores of HC. The best fitting model structure was: head circumference (in SDS)  =  ßPercentages of missing values in the covariates ranged from 0% to 36.2% . BecauseOf the 3383 children, 33.2% of their mothers had a high educational level and 14.6% had a low educational level. Compared with mothers with a high education, those with a low education were on average younger, shorter, more likely to smoke and less likely to drink alcohol during pregnancy. Fewer of them started and continued breastfeeding, they had higher psychopathology scores, more of them had financial difficulties, more had unplanned pregnancies (p<0.001) and more of them suffered from preeclampsia (p = 0.030). Their children were on average lighter at birth and had a shorter gestational duration, a shorter height at 1 month and a lower weight at 1 month (p<0.001) and at 3 months (p = 0.033) of age .Significant differences were observed in mean HC SDS per educational level at 1, 3, 6 and 11 months. Post hoc analyses showed that children from mothers with the highest educational level had significantly larger HCs than children from mothers with mid-low and low educational levels at all ages .At 1 and 3 months of age, the differences in HC for the low and/or the mid-low education group were attenuated with more than 10% by individual adjustment for maternal and paternal height, pre-pregnancy BMI, birth weight, gestational age, child’s weight and height and breastfeeding . Birth wAt 6 months, an attenuation of 10% was observed after individual adjustment for maternal and paternal height, pre-pregnancy BMI, smoking during pregnancy, birth weight and gestational age . When adResults from our linear mixed models showed that HC differences between the various educational subgroups became smaller with increasing age due to declining HC growth in the higher educational subgroups. Compared with children of mothers with high educational levels, those whose mothers had mid-low and low educational levels showed a relatively faster growth of head circumference  .This study found children of mothers with a low and mid-low educational level to have significantly smaller HCs at the age of 1, 3 and 6 months compared to children of mothers with a high educational level. The factors which mainly explained the socioeconomic inequalities in HC were found to be birth weight, gestational age and the child’s length and weight.The HC differences became smaller with increasing age. It has been suggested that infants whose intrauterine growth was constrained tend to grow faster postnatally to compensate In our study, the HC differences could mainly be explained by shorter gestational age and lower birth weight in the lower educational subgroups. At 1 and 3 months of age, the child’s weight and length only partially contributed to the HC differences. This suggests that socioeconomic inequalities in HC arise prenatally. It underlines the importance of preventing inequalities of birth outcomes arising in pregnancy, as they influence not only fetal The potential mediators included in this study partially explained the educational differences in HC at 1 and 3 months. The remaining effect may be due to other factors, such as environmental and genetic factors Parental height also contributed to HC differences between the different socioeconomic subgroups. The effect of parental height was strongest at 6 months of age. This is in agreement with the study of Smit et al., who found that heritability of head size is very low or absent in infants younger than 3 months and heritability estimates were 90% at 4 to 5 months Smoking during pregnancy contributed to larger HC differences at 6 months. This is in line with other studies which found impaired postnatal growth of infants prenatally exposed to cigarette smoking Our study also showed that lower educated subgroups have factors that have suppressive effects on a small HC. For instance, high maternal BMI was positively associated with HC. This finding was also observed for neonatal HC and maternal BMI The differences in HC between the various maternal educational levels could not be explained by psychosocial factors, drinking alcohol during pregnancy, smoking during pregnancy in the first 3 months, or having gestational diabetes. Since these factors are found to be negatively associated with birth weight and gestational age, they might act on HC via indirect pathways The study of Silva et al. showed that a lower maternal educational level was associated with slower fetal growth and this effect appeared to be strongest for fetal brain, although this was not significant The main strength of this study lies in its population-based prospective design, in which a large number of women were enrolled early in pregnancy, and in the fact that information on relevant potential confounders and mediators was available. Limitation of this type of design is the sensitivity to selection bias, information bias and residual confounding due to unmeasured covariates. The choice whether to consider a factor a confounder or a mediator was based on pre-existing knowledge about social and biological determinants of growth. It is not always a straightforward one, though, and is sometimes arbitrary. Another source of discussion when defining a factor as a mediator, is the causal relationship that is inferred between SEP and that factor. Because actual establishment of causality is only possible with experimental data, one cannot exclude the possibility that the association between SEP and the mediator is not causal.Although there are other measures of SEP, we used maternal educational level as indicator of SEP. Education is an important determinant of employment and economic circumstances, and thus reflects material resources. It also reflects non-economic social characteristics, such as general and health-related knowledge, which influences health behavior, literacy, problem-solving skills and prestige To various extents, our results may have been influenced by the following limitations. Information on pre-pregnancy BMI, smoking and alcohol consumption during pregnancy and psychosocial determinants was derived from questionnaires. This may have induced some misclassification. Misclassification of potential mediating risk factors may have contributed to the lack of explanation of the observed association between maternal education and HC. Fetal growth restriction can lead to an underestimation of the effect of SEP on HC, because the gestation may be less certain for disadvantaged women if they have a higher proportion of unplanned pregnancies. Ultrasound correction of gestational age may then induce a bias if there is fetal growth restriction. In our study, however, there were no differences in the prevalence of children born with fetal growth restriction by educational subgroups . The response rate among Dutch pregnant women in The Generation R Study was relatively high (68%), but there was some selection towards a relatively highly educated and somewhat healthier study population, which may have led to some underestimation of the estimated effect of low maternal education This study adds to the small body of literature concerning socioeconomic inequalities of HC in infancy.Our results add to the evidence of the negative impact of a low SEP on different aspects of growth in childhood. These findings warrant a public health strategy aimed at tackling these inequalities, a strategy that should already start during the preconception period and should include the prevention of a low birth weight and short gestational age Figure S1Mean head circumference SDS minus mean length SDS, stratified by maternal educational level. SDS  =  standard-deviation score *Mean head circumference SDS - mean length SDS is significant different in the low educational subgroup from that in the subgroup with high education at level p≤0.05. All values are adjusted for maternal age and parity.(TIF)Click here for additional data file.Table S1a.General characteristics of the excluded population (n = 770) BMI = body mass index, SDS = standard deviation scores, HC = head circumference. aValues are percentages or means (SD) for the total excluded population. bP-values are calculated with the Chi-square test for categorical variables and ANOVA for continuous variables compared to the variables of the total included population. Values are calculated with non-imputed data.(DOC)Click here for additional data file.Table S2Change in head circumference differences (in SDS) for maternal educational level after adjustment for potential mediators. B = effect estimate, CI = confidence interval, BMI = body mass index. a Change a, b and c represent the changes in effect estimates for mid-high, mid-low and low education relative to model 1 (includes confounders) after individual adjustment for potential mediators (100×(B model 1– B model 1 with mediator)/(B model 1 )). The percentages in bold attenuate with ≥10%.(DOC)Click here for additional data file.Table S3a.Longitudinal associations between maternal educational level and child’s head circumference aValues are based on linear mixed models (based on 16958 measurements) and reflect the difference in growth in standard deviation score (SDS) of head circumference per educational subgroup compared to the high subgroup, which is the reference group. bP-value reflects the significance level of the estimate.(DOC)Click here for additional data file.


The role of apolipoprotein E (Apo E) gene polymorphisms in the etiology of recurrent pregnancy loss (RPL) is not clearly understood. We evaluated this polymorphism in unexplained pregnancy losses in a group of Turkish women. In our prospective case-control study, 45 well-characterized RPL cases were examined for their Apo E genotypes, based on restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-amplified fragments. The observed genotypes were compared with those obtained from equal number matched controls. We observed similar Apo E genotypes and E2, E3 and E4 allele frequency distribution among RPL patients and controls. The allele frequencies obtained in patients and controls, respectively, were as follows: E2=8 (9%) and 12 (13.4%) (P=0.342), E3=66 (73.3%) and 60 (66.6%) (P=0.328) and E4=16 (17.7%) and 18 (20%) (P=0.703). Our data did not support the association of Apo E gene polymorphisms with RPL as reported by previous studies. We endorse adequate characterization of RPL cases and adequate sample size prior to addressing such studies. Recurrent pregnancy losses (RPLs) affect 1% of women and there are a number of factors playing a part. RPL is one of the least understood pathological processes, in spite of being one of the most common reproductive problems. The reason for 68% of RPL cases is idiopathic. In at least 50% of couples with RPL, evaluation, including parental karyotyping, hysterosalpingography or hysteroscopy and antiphospholipid antibody testing may be normal  is a protein that plays a key role in the metabolism of cholesterol and triglycerides by binding to receptors in the liver to mediate clearance of chylomicrons and very-low-density lipoproteins from the bloodstream . The priA total of 90 women were included in this case-control study. Of these, 45 women had a history of ≥2 consecutive spontaneous abortions with no previous history of successful pregnancy and 45 fertile women had at least one live birth and had no history of spontaneous abortion. Additionally, they had no previous history of pre-eclampsia, preterm delivery, ectopic pregnancy or any other pregnancy-related complications, as well as other non-obstetrical conditions, including chromosomal abnormalities, Mullerian duct defects, abnormal immunological and endocrinological tests and thrombophilia. Women with alcohol usage and smokers were excluded from the study. All the samples were collected from patients attending the outpatient department of the Eskişehir Osmangazi University Department of Gynecology and Obstetrics. All the couples experiencing RPL were evaluated. Chromosome analyses were performed on all subjects. All women with RPL were examined by ultrasonography or hysterosalpingography for detection of anatomical abnormalities of the genital tract. They also had blood drawn for testing for immunological risk factors, including antiphospholipid antibodies, antinuclear antibodies, antithyroid antibodies and lupus anticoagulant, to rule out other causes of recurrent miscarriage. Blood samples (5 ml) from the controls and RPL women were collected in ethylenediamine tetraacetic acid (EDTA)-coated collection vials and DNA was extracted using Qiagen DNA extraction kits . This study was approved by the Eskişehir Ethics Committee No. 1. Written informed consent was obtained from all participants prior to registering for the study.Fifty nanograms of genomic DNA was amplified in 25 liters PCR buffer containing 1 unit Taq DNA polymerase. A 228 bp fragment of the human Apo E gene was amplified with specific primers. The resulting PCR fragments were analyzed with a probe  and with probes labeled with LightCycler Red 640 . The Apo E codon 112 exhibits a Tm of 49.0°C in channel 530 for allele variant 112C and a Tm of 59.0°C in channel 530 for allele variant 112R. The Apo E codon 158 exhibits a Tm of 63.0°C in channel 640 for allele variant 158R and a Tm of 53.0°C in channel 640 for allele variant 158C. The use of a color compensation file generated with the LightMix kit - Color Compensation 530/640 is a prerequisite to run the duplex reaction. The supplied control DNA allows for the accurate comparison with unknown samples. aNot significant. Apo E, apolipoprotein E; RPL, recurrent pregnancy loss.The frequencies of gene mutations were compared between women experiencing RPL and the controls using a 2×2 contingency table with Fisher’s exact test . A two-tailed P-value <0.05 was considered to indicate a statistically significant difference.Our study included 45 women with RPL and 45 women for the control group. The mean age of the RPL group was 33±0.78 years and the number of previous miscarriages ranged from 2 to 5. The mean age of the control group was 33.5±0.7 years and there was no significant difference between the groups (P>0.05). The mean number of weeks before pregnancy loss in the patient group was 8.3±0.32 weeks . The mean birth time for the control group was 39.3±0.1  weeks.The frequency of the Apo E genotypes for patients and controls are shown in Apo E3 was the most frequent allele and Apo E2 was the rarest allele in the two groups. There was no significant difference in Apo E alleles in the two groups. Apo E2 was observed less in the patient group than in the control group; however, this was not statistically significant. There was no significant difference in Apo E genotype between the RPL and control groups. The most frequent genotype was Apo E3/E3 for the two groups.In the RPL group, the mean spontaneous abortion rate was 2.4±0.65 for the Apo E3/E3 genotype and 2.7±0.95 for the Apo E4/E4 genotype P>0.05; . In the et al(In this study, we examined Apo E gene polymorphisms and their association with RPL. According to our results, there is no significant correlation between RPL and Apo E gene polymorphisms. The Apo E4 allele has been shown to be associated with an elevated risk of recurrent miscarriage in a previous study . Furtheret al reportedet al. They coet al(Apo E genotype distribution differs among populations. Eichner et al reviewedApo E is a glycosylated protein characterized by its wide tissue distribution and multiple functions. Apo E polymorphisms have been extensively studied in a variety of diseases, including multiple sclerosis  and AlzhThe role of thrombophilia in the causation of RPL has been proven. Inherited thrombophilia is considered to be a multifactorial condition in which susceptibility is conferred by a number of genetic polymorphisms . This maet al(et al(Corbo et al identifi al(et al compared al(et al,17. In a al(et al.We conducted this study on a group of 45 RPL patients and their genotype frequencies were compared with those of 45 control samples. We observed no correlation between RPL and Apo E polymorphisms. Further studies should use an appropriate sample size. The confusion regarding the role of Apo E in RPL may be addressed through multicenter studies where samples of different ethnicities, using the same selection criteria for the RPL group and controls, are used.In conclusion, our findings show that further studies on Apo E gene polymorphisms in RPL are not required. With growing awareness of the correlation between genetic factors influencing hemostasis and pregnancy-related disorders, documentation of thrombotic causes are important due to the potential of performing randomized controlled clinical trials to determine the effect of thromboprophylaxis in such cases.


Most research examining birth history (i.e. related birth complications) and developmental milestone achievement follow outcomes for infants at-risk with very specific birth weight categories and gestational age classifications. The purpose of this study was to examine how birth weight relates to infants’ birth histories and developmental milestone achievement when they fall into a variety of birth weight and gestational age categories.In the current study, we examined birth histories and onset ages for developmental milestones by analyzing a convenience sample of anonymous existing data from 663 developmental histories completed by parents at the time of an initial evaluation at a pediatric outpatient occupational therapy clinic. Infants fell into 3 birth weight categories; low birth weight (LBW), normal birth weight (NBW), and high birth weight (HBW) and 3 gestational age classifications considered with birth weight; small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA).NBW, AGA, and SGA infants with related birth complications had lower birth weights than infants without birth complications. Larger birth weights were associated with earlier ages for independent sitting for HBW infants, earlier ages for eating solids for NBW infants, and earlier walking onsets for LBW and NBW infants. Higher birth weights were also linked with rolling at a younger age for LGA infants, earlier walking and speaking words for AGA infants, and sooner independent sitting for SGA and AGA infants.Our findings suggest that birth weight and gestational age categories provide unique insights into infants’ birth history and developmental milestone achievement. Infants’ weight at birth is a strong predictor of neonatal health outcomes such as chances of survival, risk of medical complications, and timing for the achievement of development milestones . The heaWhen determining neonatal health outcomes, it is important to consider infants’ gestational age along with birth weight. For example, ELBW infants’ survival chances are related to gestational age: fewer weeks of gestation correlate with lower chances of survival . Also, iMost research examining health and developmental outcomes based on birth weight and gestational age follow outcomes for infants at-risk with very specific birth weight categories and gestational age classifications  into infancy -5,8-11. Data for this study were collected as part of a larger study with a total of 1,000 responses, which examined the incidence of pre-, peri- and post-natal factors in children identified with sensory processing problems. In the current retrospective study, participants were a convenience sample of 663 children between 4–12 years of age who received a comprehensive sensory integration-based occupational therapy evaluation at a private pediatric outpatient occupational therapy clinic (OTA-Watertown). This study is unique in that it examines the issue of birth weight and related milestone development in a population of children with sensory processing problems.In the current study, we only included participants with recorded birth weights. Participants were primarily Caucasian and from a middle to upper-middle socio-economic status. The sample included 74% boys and 26% girls. This study had a disproportionate number of boys because boys are significantly more likely to have sensory processing problems and thus seek clinical services.Data for this study were responses to questions on the OTA-Watertown Developmental/Sensory History completed by parents at the time of the participants’ evaluation. The developmental/sensory histories were mailed to parents generally two weeks prior to the evaluation. Parents completed the developmental/sensory histories at home and returned them to OTA-Watertown via mail prior to the evaluation session or in person on the day of the evaluation. In the current study, we analyzed parents’ anonymous, de-identified responses to questions related to their children’s birth history and developmental milestones. Milestones for children born at LBW and ELBW were corrected for prematurity. Gestational age classifications were based on growth charts. Inclusion criteria were that the developmental/sensory histories be completed between July 2001 and October 2010 and that children be between 4 and 12 years old. All developmental histories during this time period were considered for inclusion in this study. Exclusion criteria were that children not be diagnosed with Autism or Downs Syndrome. See Table All statistical analyses were conducted using SPSS 16.0 statistical software. Birth weight was the main dependent variable. The independent variables were: 1) birth weight category, 2) gestational age classification considered with birth weight, and 3) birth history. The results were presented as means and standard deviations. Independent t-tests were conducted to analyze the influence of the independent variables on the dependent variable. Separate Pearson’s correlations for birth weight categories and gestational age classifications considered with birth weight were conducted to examine relationships between the age at which developmental milestones were achieved and birth weight. To test whether parents’ responses differed according to their children’s age when developmental histories were completed, a Pearson’s correlation was run to examine the relationship between children’s age at evaluation and each variable. All tests were subjected to Bonferroni corrections to reduce experiment-wise errors.n = 3), VLBW (n = 8), LBW (n = 39), NBW (n = 513), and HBW (n = 100) children. Of the 663 in our sample, 91 were SGA, 509 were AGA, and 63 were LGA. Tables Our sample of 663 included ELBW (n’s (n = 3 and n = 8 respectively). However, all LBW, NBW, and HBW infants contributed data for birth history. For developmental milestones, responses varied based on how many parents provided a specific age at which the milestone was achieved. For example, instead of listing the exact age at which the milestone was achieved or leaving the item blank, some parents wrote whether their infant achieved the milestone at an early, normal, or late age. For rolling, walking, saying words, independent sitting, eating solids, speaking sentences, and crawling this accounted for 11%, 4%, 11%, 10%, 11%, 12%, and 10% of the responses respectively. These responses were excluded from the analyses to allow for exact ages to be used rather than qualitative estimations of milestone achievement. Similar to related birth complications, ELBW and VLBW infants were excluded because of the small n for those groups. Related birth complications that were reported by birth weight category were: for LBW children a swollen head, for NBW children head bruises, face or head abrasions, broken clavicles, shoulder dystocia, a swollen head, umbilical cord around the neck, minocin, low muscle tone, dislocated hip, effusion of the forehead or nose, cranial bleeding, eye irritation, a benign mass on the neck, or a hernia, and for HBW children head bruises, face or head abrasions, broken clavicles, shoulder dystocia, low muscle tone, or cyanosis. According to gestational age classification considered with birth weight, reported related birth complications included for SGA head bruising, a swollen head, and the umbilical cord around the neck, for AGA head bruises, face or head abrasions, broken clavicles, shoulder dystocia, a swollen head, umbilical cord around the neck, minocin, low muscle tone, dislocated hip, effusion of the forehead or nose, cranial bleeding, eye irritation, a benign mass on the neck, or a hernia, and for LGA head bruises, face or head abrasions, broken clavicles, shoulder dystocia, low muscle tone, or cyanosis.Although the total sample included 663, a variable number of responses were gathered due to missing data. Missing data occurred because parents sometimes left items blank on the mailed developmental histories. If items were left blank for a particular dependent variable, those infants were omitted from the analyses for that variable. For birth history, ELBW and VLBW groups were excluded from the analyses due to small t(511) = 3.92, p = .0001. Of the infants with normal birth weights and birth complications 16% were premature, 5% were breech, 25% required forceps, 6% sustained birth injuries, 24% had jaundice, and 8% spent time in intensive care. Analyses with gestational age classification considered with birth weight as the independent variable showed that infants who were SGA had lower birth weights if they had related birth complications compared to SGA infants with no birth complications; t(89) = 2.47, p = .016. Of the SGA infants with birth complications 73% were premature, 8% were breech, 25% required forceps, 8% sustained birth injuries, 46% had jaundice, and 42% spent time in intensive care. We also found that AGA infants with birth complications had lower birth weights than AGA infants with none; t(507) = 2.35, p = .019. For AGA infants who had birth complications, 11% were premature, 5% were breech, 24% required forceps, 5% sustained birth injuries, 23% had jaundice, and 7% spent time in intensive care. Pearson’s correlations between birth weight and children’s age at evaluation were not significant for children with and without related birth complications .We examined whether birth weight is associated with related birth complications. Tables We examined the relationship between the age at which children achieved developmental milestones  and their birth weight as infants. Tables r(61) = −0.42, p = .001). Heavier birth weights for NBW was linked with eating solids sooner (r(222) = −0.56, p = 0.018). Higher birth weights were associated with earlier walking onsets for LBW (r(28) = −0.58, p = .001) and NBW (r(455) = −0.11, p = 0.021) children. No significant relationships were found between birth weight category and rolling, crawling, saying words, or speaking sentences . Birth weight was not correlated with age at evaluation for any developmental milestones .Pearson’s correlations for each birth weight category showed relationships between birth weight and ages at which children achieved independent sitting, walking, and eating solids. Larger birth weights for HBW children was correlated with earlier independent sitting (r(31) = −0.36, p = 0.048) whereas higher birth weights for AGA children was correlated with walking (r(451) = −0.12, p = 0.01) and saying words (r(340) = −0.13, p = 0.019) at younger ages. Higher birth weights were also associated with sitting independently at a younger age for SGA (r(51) = −0.36, p = 0.009) and AGA (r(325) = −0.13, p = 0.023) children. No relationships were found between gestational age classification considered with birth weight and crawling, eating solids, or saying sentences . The only significant correlation for age at evaluation was with rolling for LGA infants (r(30) = 0.45, p = 0.013); older ages at evaluation were associated with rolling later.We also ran Pearson’s correlations for each gestational age classification considered with birth weight on birth weight and developmental milestone achievement. We found significant relationships between birth weight and rolling, independent sitting, walking, and saying words. Higher birth weights for LGA children was associated with rolling at a younger age  requiring professionals to deliver infants expediently. Lower birth weight may have been related to birth history for AGA and NBW infants in our sample because these infants also had complications necessitating a swift delivery that required assistance (e.g. forceps). Also, our sample consisted of children who were being evaluated for sensory processing disorder, so there may have been a higher incidence of birth complications in this sample even for AGA and NBW infants .We found that larger birth weights were associated with earlier onset ages for some developmental milestones. However, the relationship between birth weight and milestone achievement varied according to birth weight category and gestational age classification considered with birth weight. For gestational age classification considered with birth weight, we found that heavier SGA and AGA infants sat earlier and that heavier AGA infants walked and said words earlier. Previous studies have shown that SGA infants tend to have less body fat than LGA infants and some AGA infants , and thaMastering postural control sooner with independent sitting and walking may predispose children to achieving other developmental milestones sooner; we may have found a relationship between birth weight and eating for NBW infants as well as saying words to AGA infants because their ability to be upright  allows for eating solids earlier and for engaging in interactions with others sooner. Meeting motor milestones earlier has been shown to foster meeting other developmental milestones earlier. For instance, the beginning of crawling and walking are associated with increases in verbal  and cognThe limitations to this study are that: 1) the retrospective nature of this study did not allow us to control how many participants were represented in categories based on sex, birth weight category, gestational age classification considered with birth weight, the presence of incomplete histories, or what parents’ exact definition of the onset of milestones were and 2) the fact that we sampled our data from a clinical population may limit the generalizability of our findings, but provides important information on describing this population of children with sensory processing disorder. Future studies involving the collection of prospective data from non-clinical sources are underway to ameliorate these limitations. This study is a first step into examining how variations in birth weight and gestational age considered with birth weight categories relate to birth history and developmental milestone achievement.Our findings suggest that birth weight and gestational age considered with birth weight categories provide unique insights into infants’ birth history and developmental milestone achievement. Future studies may help to examine how information about birth weight category and gestational age considered with birth weight can assist health professionals to predict and to treat impairments down the road for children.The authors declare that they have no competing interests.SG participated in data analyses, project conceptualization, and manuscript writing. TMB and AT participated in project conceptualization and manuscript writing/editing. ES entered, processed, coded, and analyzed participants’ responses. All authors read and approved the final manuscript.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2431/13/29/prepub


A dentigerous cyst is the most common developmental odontogenic cyst and is frequently noted as an incidental finding on radiographs. The most common teeth affected are impacted mandibular third molars and permanent maxillary canines. This case involves a dentigerous cyst encompassing the right and left impacted mandibular canines and crossing the midline. This is, to the best of our knowledge, the first reported case of a dentigerous cyst encompassing non-adjacent teeth and crossing the midline.The patient presented to our orthodontic clinic for treatment of malocclusion. The patient was a 10-year, one-month-old Caucasian girl with a dentigerous cyst encompassing the right and left impacted mandibular canines and crossing the midline.This case involves an unusual clinical and radiographic presentation of a dentigerous cyst. It shows a new variant of presentation that medical professionals, specifically dentists and radiologists, should be aware of, since a dentigerous cyst crossing the midline has not been previously reported as far as we are aware. This additional knowledge is important for inclusion on differential diagnosis lists and aids in the development of a proper treatment plan. Dentigerous cysts are the most common developmental odontogenic cysts, accounting for approximately 25% of all odontogenic cysts of the jaws. They are frequently noted as an incidental finding on radiographs because a majority of these cysts are asymptomatic and are most commonly associated with impacted mandibular third molars and permanent maxillary canines ,2. A denA Caucasian 10-year, one-month-old girl presented to the College of Dentistry for an initial orthodontic work-up. A digital pantomograph and a standardized lateral cephalometric skull radiograph  were made. The pantomograph showed impacted mandibular canines, both of which were inclined mesially in a nearly horizontal position and located in the region apical to the mandibular incisors. There was a well-defined radiolucent area evident around the crown of the right mandibular canine that was continuous with the cemento-enamel junction. The radiolucent area measured approximately 20mm in width and 11mm in height. The appearance was consistent with a dentigerous cyst encompassing the crown of the right mandibular canine  using a 17cm × 16cm × 17cm field of view to evaluate the position of the canines and the dentigerous cyst. The resultant data were reconstructed, and multi-planar and orthoradial views were examined. The coronal and axial slices revealed that the dentigerous cyst was larger than was apparent on the digital pantomograph. The cyst encompassed the crowns of both the right mandibular canine and the left mandibular canine. The border of the dentigerous cyst was continuous with the cemento-enamel junction of the impacted permanent mandibular canines Figure . The appSurgical exposure of the canines with an incisional biopsy of the surrounding dentigerous cyst was performed by a periodontist (JBP) three months after the initial appointment. It was noted that the dentigerous cyst border was continuous with the cemento-enamel junction of both impacted permanent mandibular canines Figure . The incOne year later peri-apical radiographs of the mandibular canines Figure  were madThere were no previous radiographs showing the patient's mandibular anterior teeth to determine whether the cyst originated as a single dentigerous cyst that enlarged and grew to encompass the other impacted canine. There are other reported cases of a dentigerous cyst enlarging and encompassing other adjacent teeth -5. The oThis case describes the presentation of a dentigerous cyst that has not been previously reported. This new presentation shows that a dentigerous cyst can encompass multiple non-adjacent teeth in addition to the possibility that a dentigerous cyst might also cross the midline. Previously, these two variants would lead to a differential diagnosis not including a dentigerous cyst. This is important for medical professionals to be aware of, specifically dentists and radiologists, so that an accurate differential diagnosis can be made to determine the best treatment for the patient.Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.The authors declare that they have no competing interests.SG interpreted the radiographs and the cone-beam computed tomography scan. PS performed the orthodontic movement of the mandibular canines once they were exposed. JP performed the incisional biopsy, curettage, and exposure of the mandibular canines. PG performed the histological examination of the biopsy. All authors read and approved the final manuscript.


The global Low Birth Weight (LBW) rate is reported to be 15.5% with more than 95% of these LBW infants being from developing countries. LBW is a major factor associated with neonatal deaths in developing countries. The determinants of low birth weight in Nepal have rarely been studied. This study aimed to identify the factors associated with small size at birth among under-five children.2) followed by logistic regression. Complex Sample Analysis was used to adjust for study design and sampling.Data from the 2011 Nepal Demographic and Health Survey (NDHS) were used. The association between small size at birth and explanatory variables were analysed using Chi-square tests  children were reported as small size at birth. Of 1922 infants whose birth weight was recorded, 235 (11.5%) infants had low birth weight (<2500 grams). The mean birth weight was 3030 grams (standard deviation: 648.249 grams).The mothers who had no antenatal visits were more likely (odds ratio (OR) 1.315; 95% confidence interval (CI) (1.042-1.661)) to have small size infants than those who had attended four or more antenatal visits. Mothers who lived in the Far-western development region were more likely to have ) small size infants as compared to mothers from the Eastern development region. Female infants were more likely ) to be at risk of being small than males.One in every six infants was reported to be small at birth. Attendance of antenatal care programs appeared to have a significant impact on birth size. Adequate antenatal care visits combined with counselling and nutritional supplementation should be a focus to reduce adverse birth outcomes such as small size at birth, especially in the geographically and economically disadvantaged areas such as Far-western region of Nepal. Birth weight has a significant impact on newborn mortality . Low birA United Nations Children’s Fund report noted that the global LBW rate was 15.5% and more than 95% of these LBW infants lived in developing countries . Nepal hThe NDHS is nationally representative cross sectional survey using two stage cluster sampling ,8. In fiWhen (NAME) was born, was he/she; very large, larger than average, average, smaller than average, or very small? The survey also recorded the birth weight based on the following questions: Was (NAME) weighed at birth? How much did (NAME) weigh? [Record the weight in Kilogram ]. However, the majority of the births in Nepal occur at home without proper measurement of birth weight.The NDHS 2011  asked abIn 2011 survey, only 36.9% of mothers were able to recall or report birth weight from the child health card. Further, there was a significant difference (p < 0.05) between mothers who were able to report and not report the birth weight. We found that the birth weight was reported more often by the mothers who are educated (p < 0.001), who delivered in a health facility (p < 0.001) and who were from the higher wealth quintile (p < 0.001). Therefore, including birth weight and more specifically low birth weight in the analysis would have introduced a selection bias due to such socio-economic differences.Studies from developing countries have shown that mother’s recall of the baby’s size could be used as the proxy for birth weight -14. BaseThe explanatory variables included in this study were based on the literature published from NDHS data -17 and sManusmriti, a traditional Hindu scripture  which is further categorised as (i) Advantaged - Brahmin, Chhetri, Thakuri Sanyasi, Newar, and Gurung; (ii) Disadvantaged-Janjati including indigenous groups; and (iii) Disadvantaged-Dalit castes based on the available literatures and similarities between different caste groups [A U-shaped relationship has been suggested in some studies to explain the effect of maternal age on birth weight with teenage mothers and those of higher age being at greater risk of having LBW infants -21. There groups ,23. Of te groups . This isure 16, 1 which ise groups . The NDHe groups . The cooe groups : (i) rel2). The significant factors identified in the univariate analysis were further examined using multiple logistic regressions. We used hierarchical modelling strategy analysis so that the effects of different levels of the variable can be examined [Prevalence of small size at birth was obtained by using descriptive statistics (frequency distribution). Association between small size at birth and explanatory variables of interest was first evaluated by using Chi-square test  were included in this analysis after excluding 66 multiple births due to their known high risk of LBW. Based on the recorded birth weight , the mean birth weight was 3030 grams , 12.2%  of infants were LBW < 2500 grams.Table The characteristics of the mother-child pairs included in the survey are summarised in Table The results from univariate analyses are presented in Table In an alternative model we included only the last born singleton children (N = 4051) and ran multiple regression model with stepwise backward elimination including the variables: wealth status, development region, sex of child, number of antenatal care, iron supplementation consumption, tobacco smoking, mother’s education , mother’s occupation and type of cooking fuel (Not shown in table). Results were comparable to Model 3, showing that development region, sex of children and number of antenatal visits attendance were significantly associated with small size at birth. It was also found that children born to: mothers residing in the Far-western region of Nepal ), mothers who did not attend any ANC visits ) or attend 1-3 ANC visits only ), were more likely to be smaller size at birth. Similarly, female infants ) were more likely to be smaller size at birth.This study found that one in every six infants in Nepal was small size at birth as reported by mothers, and that three factors: (1) antenatal visits, 2) sex of child, and (3) the development region were significantly associated with birth size. The proportion of smaller sized infants 16%) was slightly lower than in 2006 NDHS (19.2%) and 2001 NDHS (21.0%)  sex of c and in I% was sliAntenatal care (ANC) attendance is the starting point for seeking care during pregnancy and childbirth. Utilisation of ANC is likely to improve dietary practices, monitor and encourage recommended weight gain during pregnancy, improved uptake of nutrient supplements, and improve neonatal outcomes ,29. PoorRemoteness affects the location of health facilities, health service utilization, food choices, food availability and employment as well as other social services. It has been reported as a risk factor for LBW in Pakistan , India  and IndoCigarette smoking has been associated with LBW in many studies ,37. In aCooking fuel, while not found to be significantlyassociated with LBW in this study, has been found a risk factor in India  and otheNepal has placed great importance on maternal and child health since endorsing the MDG . The curThere are a number of strengths of this study. Firstly, it is based on national level data that used validated questionnaires and methodology . The NDHThe current study indicates the need for targeted interventions aimed at decreasing the high rate of LBW in Nepal which in turn should reduce the neonatal and infant mortality rates. Even if the ANC may not have a direct causal link to low birth weight, ANC attendance should lead to better nutritional status of mothers and the adoption of healthy behaviours that reduce LBW rates ,31,47. AThe present study revealed one in six infants born had small size as perceived by the mothers. The mothers who did not have any ANC visits and who were from the Far-western region were more likely to have small infants. This suggests that improving antenatal care and focusing the Far-western region should be in priority to address LBW in Nepal. During ANC visits, educational interventions to improve the maternal nutrition during pregnancy could help to reduce the prevalence of LBW. Future observational studies should examine the effect of other modifiable risk factors of LBW such as medical service utilization, food security, mother’s nutritional status during pre-pregnancy and pregnancy, and other health related factors that would expand existing knowledge on the risk of LBW in Nepal.The authors declare that they have no competing interest.VK conceived the concept of analysis. VK performed statistical analyses and drafted the manuscript. KS and YZ supervised the analysis, interpretation of the results, and revised the manuscript. RK contributed in literature review, analyses, interpretation of results and manuscript revision. All of the authors agreed on the final manuscript.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2393/14/32/prepub


Some patients with Coronary Artery Disease (CAD) have no well-known risk factors of this disease, but are diagnosed with cardiovascular events. The present study aimed to assess the association between Apo A1 and ApoB and the severity of CAD and determine whether these parameters are better predictors of Ischemic Heart Disease (IHD).In this case control study, 271 individuals who were suspicious of having CAD and had been referred to Arak Amir-al-Momenin hospital underwent coronary angiography. Based on the results of angiography, the participants with presence or absence of coronary artery stenosis were allocated into the case and the control group, respectively. The severity of CAD involvement was determined by Gensini score. The data were entered into the SPSS statistical software and analyzed through parametric and non-parametric tests, sensitivity analysis, and logistic regression.The results revealed no significant correlation between apoA-1 and severity of CAD involvement (GS) . However, a significant correlation was found between apoB and GS . Logistic regression model showed ApoB, sex, DM and, FH as the only proper predictors of IHD . In comparison to angiography for diagnosis of CAD, ROC analysis represented ApoB as a more useful predictor (P = 0.023).In addition to measurement of conventional parameters for assessing CAD high risk groups, according to the results of this study using ApoB would be resonable as well. Further investigations are recommended to clear the problem. Cardiovascular diseases are prevalent around the world as well as in Iran. Among these diseases, atherosclerosis is one of the major causes of death worldwide . KnowingMoreover, Sabino et al. in 2008 showed that after controlling the effect of variables, such as age, sex, smoking, hypertension, and dyslipidemia, APO B and APO B / APO A1 ratio were independently associated with brain stroke and peripheral vascular disease in young adults . BesidesSweetnom et al. in a prospective study showed a strong relationship between the level of APO lipoprotein B and the incidence of Ischemic Heart Disease (IHD). However, no such relationship was found after adjustment for total cholesterol level. Similarly, a strong correlation was observed between the low level of APO lipoprotein A 1 and the incidence of IHD. However, this correlation disappeared when the HDL level was added to the model . NeverthConsidering the above-mentioned contradictions, it is necessary to perform more investigations, especially in the Iranian community. Hence, the present study aims to assess the relationship between APO lipoproteins and the severity of CAD.This case control study was conducted on all the individuals who were suspected for having CAD and had been admitted to the angiography section of Amir-al-Momenin hospital, Arak, Iran. The demographic data, medical history of CAD, history of coronary angiography / angioplasty, hypertension, diabetes mellitus, and smoking, and family history of CAD in the first degree relatives of the patients were collected through a previously designed researcher-made questionnaire. The inclusion criterion of the study was referring to the heart angiography section of Amir-al-Momenin hospital, Arak, Iran. On the other hand, the exclusion criteria of the study were having the history of chronic renal failure, being under treatment by blood lipid lowering drugs , and being under treatment by sex hormones . Based on the results of angiography, the participants with presence or absence of coronary artery stenosis were allocated into the case and the control group, respectively.Finally, 271 patients were enrolled into the current study. After providing the participants with sufficient explanation and obtaining written informed consents from all the patients before angiography, blood samples were taken. The patients were also informed about the safety and free cost of blood sampling. All the blood samples were sent to laboratory for measurement of serum levels of lipoprotein A1, lipoprotein B, cholesterol, triglyceride, LDL, HDL, VLDL, and Fasting Blood Sugar (FBS). Lipid profile was measured using Hitachi 911 auto analyzer which had the confirmation of Food and Drug Administration (FDA). In addition, quality control was done in normal and high levels in each series. Besides, LDL was measured by the direct method. Furthermore, Minireph device, which has the capability to measure the indicators by the nephlometry method, was used to measure APO A and APO B. Then, the patients underwent angiography using Siemens angiography device (Axiom senses). The results of angiography were reviewed by two cardiologists who did not have any information about the patients' medical history. It should be noted that the patients' angiography movies were interpreted by the two cardiologists independently.The severity of CAD was determined by Gensini criteria and defined by Gensini Score (GS) . After aA total of 271 patients participated in the present study. After angiography, 160 participants (59%) were diagnosed with CAD and were consequently allocated to the case group. On the other hand, 111 subjects (41%) did not have CAD and were considered as the control group. The mean age of the study participants was 60.63 ± 12.5 years. Besides, the mean age of the CAD and the control group was 61.02 ± 11.06 and 60.7 ± 12.3 years, respectively and the difference was not statistically significant (P = 0.855).In this study, Spearman's test was used to assess the correlation between APO A1 and APO B and the severity of coronary artery stenosis measured by GS score. According to the results, no significant correlation was observed between GS and APO A1 , while GS score and APO B were correlated significantly .It should be noted that to detect the best cut off point for APO B with maximum sensitivity and specificity, coordinates of the ROC curve tables must be used. Examining this To predict the presence or absence of CAD (dependent variable), logistic regression analysis was used. The variables entered into the model (covariates) included sex, age, history of hypertension (HTN), history of diabetes (DM), family history of premature CAD (FH), cholesterol, triglyceride, HDL, LDL, VLDL, APO B, APO A1, and APO B / APO A1 ratio. Among these variables, only APOB, sex, DM, and FH were identified as the predictor variables. The covariates were analyzed through the “Entered method”. The whole prediction power of the model was 27.8% for all the variables (Nagelkerk R square). Moreover, the probability value of Hosmer-Lemeshow goodness of fit test was not significant (P < 0.072). This implies that the entered data were fitted with the model. On the basis of the classification table results, the correct prediction percents for diagnosing the patients (sensitivity) and the healthy individuals (specificity) were 52.2% and 80.5%, respectively. This result indicated that the overall accuracy of the model was 68.3%.  The results of the present study showed that among gender, age, cholesterol, triglycerides, HDL, LDL, APO A1, APO B, and the APO B / APO A1 ratio, just APo B, FH, DM and gender were the predictors of CAD. In contrast to angiography method for diagnosis of CAD, measurement of APO B level can be useful as a laboratory test. In addition, the best cut off point for APO B was 89.5. However, measuring APO A1 and APO B / APO A1 ratio cannot be useful in laboratory tests.The findings of the current study indicated no significant correlation between the LDL level and CAD. This might be due to the fact that measurement of LDL only shows the total cholesterol mass in LDL particles, but does not give any information about the number and size of the LDL particles. The size of the LDL particles has an inverse effect on their ability to cross through the arterial endothelium, penetration to intima, and risk of atherosclerosis. Nevertheless, the results showed a significant correlation between the APO B level and the severity of CAD. This might result from the fact that atherogen particles in plasma, such as LDL, HDL, and VLDL, contain APO B molecules. Indeed, APO B directly reflects the number of plasma atherogenic lipoproteins since each particle of LDL, IDL, and VLDL involves just one APO B. On the other hand, no significant correlation was observed between APO A1 and the severity of CAD.The results of the present study are in agreement with those of the study Pischon et al. conducted in Harvard University, demonstrating that APO B could predict the occurrence of CAD .Similar results were also obtained by Sabin et al. They found that after adjusting the role of gender, age, smoking, and HTN, APO B level and APO B / APO A1 ratio were independently correlated to peripheral atherosclerosis and brain stroke .In a prospective study by Sweetnam et al., after adjusting the results for cardiovascular risk factors, regardless of plasma lipids, a strong correlation was found between the incidence of IHD and high level of APO lipoprotein B as well as low level of APO lipoprotein A1. However, this trend disappeared after entering the total cholesterol size into the model. These results are inconsistent with our findings because by controlling the other variables predictor power of ApoB remained constant .The results of a study which was performed by Yazici et al. in Turkey revealed a significant correlation between the APO A1 serum level and cardiac troponins in the patients with angina pectoris. However, no significant relationship was found between the severity of CAD and the number of diseased vessels. These results are in line with our study findings regarding the correlation between APO A1 and the severity of CAD stenosis.In another study which was carried out by Habib et al. on 140 patients in Saudi Arabia, a significant correlation was observed between APO A1 and severity and extension of coronary arteries stenosis in the patients but not in the control group . HoweverAccording to the results of this study, plasma APO B test could be added to the common plasma lipid profile in laboratory tests in the individuals who are at risk of CAD. If the results of APO B laboratory test are positive, this factor should be considered as a risk factor for CAD.