Birth outcomes in the Inuit-inhabited areas of Canada

Background

Information on health disparities between Aboriginal and non-Aboriginal populations is essential for developing public health programs aimed at reducing such disparities. The lack of data on disparities in birth outcomes between Inuit and non-Inuit populations in Canada prompted us to compare birth outcomes in Inuit-inhabited areas with those in the rest of the country and in other rural and northern areas of Canada.

Methods

We conducted a cohort study of all births in Canada during 1990–2000 using linked vital data. We identified 13 642 births to residents of Inuit-inhabited areas and 4 054 489 births to residents of all other areas. The primary outcome measures were preterm birth, stillbirth and infant death.

Results

Compared with the rest of Canada, Inuit-inhabited areas had substantially higher rates of preterm birth (risk ratio [RR] 1.45, 95% confidence interval [CI] 1.38–1.52), stillbirth (RR 1.68, 95% CI 1.38–2.04) and infant death (RR 3.61, 95% CI 3.17–4.12). The risk ratios and absolute differences in risk for these outcomes changed little over time. Excess mortality was observed for all major causes of infant death, including congenital anomalies (RR 1.64), immaturity-related conditions (RR 2.96), asphyxia (RR 2.43), sudden infant death syndrome (RR 7.15), infection (RR 8.32) and external causes (RR 7.30). Maternal characteristics accounted for only a small part of the risk disparities. Substantial risk ratios for preterm birth, stillbirth and infant death remained when the comparisons were restricted to other rural or northern areas of Canada.

Interpretation

The Inuit-inhabited areas had much higher rates of preterm birth, stillbirth and infant death compared with the rest of Canada and with other rural and northern areas. There is an urgent need for more effective interventions to improve maternal and infant health in Inuit-inhabited areas.Birth outcomes are worse in Aboriginal than in non-Aboriginal populations in many developed countries, including the United States, Australia and Canada.^1–18 Inuit are the smallest Aboriginal group in Canada, with a population of about 45 000.¹⁹ Some regional and community studies have shown that Inuit experience the highest rates of infant mortality in Canada.^16–18 However, data are lacking at the national level on birth outcomes among Inuit owing to the absence of Aboriginal identifiers on birth registration forms in most provinces.In Canada, over 80% of all Inuit reside in one of four vast, sparsely populated regions: the Inuvialuit region of the Northwest Territories, Nunavut, Nunavik (northern Quebec) and Nunatsiavut (northern coast of Labrador) (Figure 1). Taken together, 80% of the population in those four regions is Inuit,²⁰ and 90% of the births are to Inuit women according to 2006 census data. This creates an opportunity to examine birth outcomes according to maternal place of residence in any of the four Inuit-inhabited areas of Canada. We conducted this study to describe birth outcomes in those areas compared with outcomes in the rest of country and in other rural and northern areas of Canada.Open in a separate windowFigure 1Inuit-inhabited communities in the Inuvialuit (dots), Nunavut (triangles), Nunavik (squares) and Nunatsiavut (stars) regions of Canada. Source: Statistics Canada population data. Base map © 2002 Government of Canada with permission from Natural Resources Canada.     

Inter-laboratory evaluation of the ISO standard 11063 "Soil quality - Method to directly extract DNA from soil samples"

Extracting DNA directly from micro-organisms living in soil is a crucial step for the molecular analysis of soil microbial communities. However, the use of a plethora of different soil DNA extraction protocols, each with its own bias, makes accurate data comparison difficult. To overcome this problem, a method for soil DNA extraction was proposed to the International Organization for Standardization (ISO) in 2006. This method was evaluated by 13 independent European laboratories actively participating in national and international ring tests. The reproducibility of the standardized method for molecular analyses was evaluated by comparing the amount of DNA extracted, as well as the abundance and genetic structure of the total bacterial community in the DNA extracted from 12 different soils by the 13 laboratories. High quality DNA was successfully extracted from all 12 soils, despite different physical and chemical characteristics and a range of origins from arable soils, through forests to industrial sites. Quantification of the 16S rRNA gene abundances by real time PCR and analysis of the total bacterial community structure by automated ribosomal intergenic spacer analysis (A-RISA) showed acceptable to good levels of reproducibility. Based on the results of both ring-tests, the method was unanimously approved by the ISO as an international standard method and the normative protocol will now be disseminated within the scientific community. Standardization of a soil DNA extraction method will improve data comparison, facilitating our understanding of soil microbial diversity and soil quality monitoring.     

Genetic instability and hypervariability in Streptomyces ambofaciens: towards an understanding of a mechanism of genome plasticity

Many Streptomyces species exhibit a very high degree of genetic instability which is usually manifested as genomic rearrangements such as large deletions. In Streptomyces ambofaciens DSM40697, two levels of genetic instability were previously described: (i) a basic genetic instability similar to that reported for other strains, and (ii) hypervariability, a phenomenon that we believe to be a new aspect of instability closely associated with DNA amplification. A large DNA region undergoes deletions, amplifications and large genomic changes strictly associated with both aspects of genetic instability. The genetic and molecular analyses of the different aspects of genetic instability allow us to propose that they result from a cascade of molecular events and to investigate the relationships between genetic instability phenomena and genome fluidity.     

Aging and prostacyclin responses in aorta and platelets from WKY and SHR rats

In spontaneously hypertensive rat (SHR) aorta, prostacyclin is an endothelium-derived contracting factor contributing to the endothelial dysfunction. This study was designed to determine whether the impairment of the prostacyclin response is influenced by aging and whether such a dysfunction is observed in platelets. Isometric tension was measured in aortic rings, and aggregation was studied in platelet-rich plasma taken from 3-, 6-, and 15-mo-old Wistar-Kyoto rats (WKY) and SHR. In aorta from 3- and 6-mo-old WKY, prostacyclin and beraprost [prostacyclin receptor (IP) agonists] produced relaxations that were enhanced by Triplion (thromboxane-prostanoid receptor antagonist). In 15-mo-old WKY, the relaxations to beraprost were maintained, but not those to prostacyclin. In SHR aorta, prostacyclin or beraprost produced no or minor relaxations, which, in younger SHR, were enhanced by Triplion. In both strains, the relaxations were inhibited by CAY-10441 (IP receptor antagonist). The relaxations to forskolin and isoproterenol were reduced with aging. When compared with those of WKY, the relaxations to isoproterenol were reduced in 3- but not in 6- or 15-mo-old SHR, whereas those to forskolin were consistently diminished at any given age. Whatever the age, prostacyclin and beraprost produced CAY-10441-sensitive inhibitions of ADP-induced platelet aggregation. Both agonists were more potent in SHR than in WKY. Therefore, in platelets from WKY and SHR, the IP receptor-dependent antiaggregant response is functional and maintained during aging. In aorta from WKY those responses are reduced by aging and, in SHR, are already compromised at 3 mo. This dysfunction of the IP receptor is only partially explained by a general dysfunction of the adenylate cyclase pathway.     

Determination of phytic acid by gas chromatography–mass spectroscopy: application to biological samples

A GC–MS method is reported for the determination of phytic acid based on purification by anion-exchange chromatography, enzymatic hydrolysis of phytic acid to myo-inositol and derivation to trimethylsilyl derivative, with scyllo-inositol as an internal standard. Analytical features of the method are: limit of detection 9 μg l⁻¹ phytic acid, linear working range 18–500 μg l⁻¹ phytic acid, and coefficient of variation 1.9%. The method has been successfully applied to a variety of biological samples: various rat organs (kidney, liver, brain and bone), human plasma and urine and kidney stones. A comparative study of sample treatments, including deproteization, lipid extraction and the presence of a chelator, is also reported. Phytic acid amounts found in rat organs ranged from 1.07 g kg⁻¹ for bone to 32.0 g kg⁻¹ for brain. Phytic acid in human plasma was of the order of 0.14 mg l⁻¹. In kidney stones, phytic acid was found in calcium containing stones.     

Coordinate involvement of invasin and Yop proteins in a Yersinia pseudotuberculosis-specific class I-restricted cytotoxic T cell-mediated response

Yersinia pseudotuberculosis is a pathogenic enteric bacteria that evades host cellular immune response and resides extracellularly in vivo. Nevertheless, an important contribution of T cells to defense against Yersinia has been previously established. In this study we demonstrate that Lewis rats infected with virulent strains of Y. pseudotuberculosis, mount a Yersinia-specific, RT1-A-restricted, CD8+ T cell-mediated, cytotoxic response. Sensitization of lymphoblast target cells for cytolysis by Yersinia-specific CTLs required their incubation with live Yersinia and was independent of endocytosis. Although fully virulent Yersinia did not invade those cells, they attached to their surface. In contrast, invasin-deficient strain failed to bind to blast targets or to sensitize them for cytolysis. Furthermore, an intact virulence plasmid was an absolute requirement for Yersinia to sensitize blast targets for cytolysis. Using a series of Y. pseudotuberculosis mutants selectively deficient in virulence plasmid-encoded proteins, we found no evidence for a specific role played by YadA, YopH, YpkA, or YopJ in the sensitization process of blast targets. In contrast, mutations suppressing YopB, YopD, or YopE expression abolished the capacity of Yersinia to sensitize blast targets. These results are consistent with a model in which extracellular Yersinia bound to lymphoblast targets via invasin translocate inside eukaryotic cytosol YopE, which is presented in a class I-restricted fashion to CD8+ cytotoxic T cells. This system could represent a more general mechanism by which bacteria harboring a host cell contact-dependent or type III secretion apparatus trigger a class I-restricted CD8+ T cell response.     

Genomics, evolution and biological functions of the pacifastin peptide family: a conserved serine protease inhibitor family in arthropods

The last decade, a new serine protease inhibitor family has been described in arthropods. Eight members were purified from the locusts Locusta migratoria (LMPI-1-2 and HI) and Schistocerca gregaria (SGPI-1-5). The light chain of the heterodimeric protease inhibitor pacifastin, from the freshwater crayfish Pacifastacus leniusculus, was found to be composed of nine consecutive inhibitory domains (PLDs). These domains share a pattern of six conserved cysteine residues (Cys-Xaa(9-12)-Cys-Asn-Xaa-Cys-Xaa-Cys-Xaa(2-3)-Gly-Xaa(3-6)-Cys-Thr-Xaa(3)-Cys) with the locust inhibitors. Via cDNA cloning, eight pacifastin-related precursors have been identified in locusts. Interestingly, additional pacifastin-related precursors have been identified in Diptera, Lepidoptera and Coleoptera utilising an in silico data mining approach.