Transmission Electron Microscopy of the Retina: A Method for Sample Preparation and Evaluation

Ultrastructural pathology is critical in the morphologic evaluation and characterization of subcellular structures in nonclinical toxicity and efficacy studies. In murine models of ophthalmologic disease, clinical examination is typically paired with other techniques like electroretinography (ERG) and/or optical coherence tomography (OCT) to more fully characterize a finding. High-quality transmission electron microscopy (TEM) can provide a critical, image-based link between these approaches, providing greater confidence in interpretation of ERG or OCT results. In addition to characterization of disease models, TEM can provide detailed visualization of retinal changes identified by clinical examination or light microscopy in nonclinical toxicity studies. The spherical shape of the eye presents unique challenges for trimming, orientation, imaging, and evaluation by TEM. The varied components of the eye require specialized approaches for embedding to facilitate successful sectioning. Controlling for the orientation of the retina is critical to consistent evaluation, driving the need for an improved method of embedding this unique and complex organ. The authors describe a method of sample preparation resulting in optimal orientation of the posterior aspect of murine eyes (rat and mouse) for TEM of the neural retina, Bruch's membrane and/or choroid, with examples from mouse ophthalmic disease models.

The importance of environment on respiratory genotype/phenotype relationships in the Inuit

BACKGROUND

Genetic and environmental influences and their interactions are central to asthma pathogenesis. This study aimed to investigate the effects of different macro-environments on asthma genotype-phenotype associations in two geographically separated populations with common ancestry.

METHODS

To accomplish this, two unselected populations of Inuit were recruited, one living in Greenland (n = 618) and the other in Denmark (n = 739). Subjects were genotyped for CD14 C-159T, SCGB1A1 A38G, ADRB2 Arg16Gly and Gln27Glu. The resulting genetic data were analysed for relationships with asthma-related parameters including lung function, ever asthma, atopy, rhinitis and dermatitis.

RESULTS

The results showed contrasting magnitude and direction of genetic associations between the two geographically separate Inuit populations. In Greenland, the ADRB2 16Arg allele was associated with male-specific lower lung function, but in Denmark the same allele was associated with male-specific higher lung function. This allele was also associated with higher incidence of ever asthma in Denmark but not in Greenland. The SCGB1A1 38A allele was associated with lower rhinitis prevalence in Greenland but not in Denmark.

CONCLUSIONS

These associations suggest that environment interacts with candidate asthma genes to modulate asthma pathogenesis in the Inuit.

Opposite gene by environment interactions in Karelia for CD14 and CC16 single nucleotide polymorphisms and allergy

BACKGROUND

Finnish Karelians have a higher prevalence of allergic disease than Russian Karelians. As both populations are generally from the same ethnic group, the Karelian population offers a unique opportunity to analyse genetic and allergic disease interactions between 'Western' and 'Eastern' environments.

OBJECTIVES

We investigated associations between allergic diseases and CD14 and CC16 polymorphisms in Finnish vs Russian Karelian women.

METHODS

Adult female Karelians (330 Finnish and 274 Russian) were recruited, examined for a range of symptoms and conditions including rhinitis, itchy rash, asthma and atopy and genotyped for CD14 C-159T and CC16 A38G.

RESULTS

For both CD14 C-159T and CC16 A38G, the risk allele for atopic phenotypes in Finnish Karelia was the protective allele in Russian Karelia. For CD14 C-159T, an interactive effect on ever itchy rash (P(interaction) = 0.004), itchy rash <12 mo (P(interaction) = 0.001) and dry cough at night in the past 12 months (<12 months) (P(interaction) = 0.011) was found; the risk allele was C in Russians and T in Finns. For CC16 A38G, an interaction was significant for ever rhinitis (P(interaction) = 0.006), rhinitis <12 mo (P(interaction) = 0.004), and marginally significant for ever hayfever (P(interaction) = 0.07), allergic eye symptoms <12 mo (P(interaction) = 0.09); their risk allele was G in Russians and A in Finns.

CONCLUSION

An Eastern vs Western environment appears to exert an effect via opposite alleles on risk of allergic diseases in adult women.

Investigations into the role of ST2 in acute asthma in children

The ST2 gene is a member of the interleukin-1 receptor family and is located on chromosome 2q12, an area of the genome that has been associated with asthma. The soluble product of the ST2 gene, serum ST2 (sST2), has previously been shown to be elevated in adult asthmatic patients. This study investigated the potential role of ST2 in children with acute asthma. Children aged 2-16 years (n = 186) were recruited on presentation with acute asthma in the emergency department. Blood was obtained on presentation and during convalescence. Variables assessed included sST2 levels, a comprehensive assembly of clinical parameters and two polymorphisms in the ST2 gene, -26999G/A, located in the distal promoter region, and ala78glu polymorphism, on exon 3. The A allele of the -26999G/A polymorphism occurred more frequently in asthmatics compared with an unselected control group (P = 0.031). Serum ST2 levels were substantially higher during acute asthma compared with levels after the attack: 0.29 ng/ml (95% confidence interval: 0.23-0.36) and 0.14 ng/ml (0.12-0.17), respectively (P = 0.001) and were inversely related to eosinophil counts during an acute asthma attack (P = 0.002). The -26999AA genotype, as well as the AC haplotype, was associated with asthma severity scores (P = 0.05 and 0.02) compared with the -26999GA and GG genotypes. Serum ST2 levels were not associated with any of the studied genotypes or haplotypes. The observed associations of ST2 genotypes and haplotypes with acute asthma and asthma severity scores as well as the phenotypic differences associated with ST2 polymorphisms suggest that ST2 may play a role in the pathophysiology of asthma.

Anti-bacterial IgE in the antibody responses of house dust mite allergic children convalescent from asthma exacerbation

Background Atopic sensitization to the house dust mite (HDM) is associated with altered antibody responses to the nasopharyngeal colonizing bacterium Haemophilus influenzae and children admitted to the emergency department for asthma exacerbation have reduced IgG responses to HDM allergens.

Objective To investigate anti‐bacterial and anti‐allergen antibody responses during convalescence from asthma exacerbation and differences found in exacerbations associated with and without viral infection.

Results IgE antibodies to the P6 bacterial antigen increased in 60% of sera during convalescence and for many children achieved titres as high as IgE titres to allergens. In contrast IgE anti‐HDM titres declined during convalescence. The anti‐bacterial IgE titres were the same in subjects with and without virus infection while the anti‐HDM IgE declined more rapidly in virus‐infected subjects. IgG titres to the major HDM allergens showed no consistent increase and the overall IgG anti‐HDM titres even declined in subjects without a virus infection. Anti‐bacterial IgG antibodies in contrast to IgE did not change. Patients with frequent episodic or persistent asthma had similar IgE anti‐bacterial titres to patients with infrequent asthma during the acute phase, although they had reduced IgG titres to both the bacteria and the HDM.

Conclusions During the period following an acute exacerbation of asthma there was a marked and specific increase in anti‐bacterial IgE compared with a reduced IgE response to HDM. This provides further support for the concept of T‐helper type 2 responses to bacterial antigens playing a role in asthma pathogenesis.

Cross-sectional and longitudinal association of the secretoglobin 1A1 gene A38G polymorphism with asthma phenotype in the Perth Infant Asthma Follow-up cohort

BACKGROUND

Associations between Clara cell secretory protein gene variants (SCGB1A1, also known as CC16, CC10, CCSP and uteroglobin) and the asthma phenotype have been found in five out of eight studies world-wide. No study has investigated the contribution of SCGB1A1 polymorphisms to the development and/or persistence of the asthma phenotype in a birth cohort followed over time.

OBJECTIVE

The aim of this study was to determine the role of the SCGB1A1 gene in the development of the asthma phenotype.

METHODS

The Perth Infant Asthma Follow-up (PIAF) cohort (n=231 unrelated infants, unselected for asthma and recruited at birth) were seen at 1 month, 6 and 11 years of age, and had a questionnaire, lung function, airway responsiveness (AR) and skin prick tests (SPTs) completed. Blood was taken at 6 and 11 years for total and specific immunoglobulin E (sIgE) and DNA extraction. SPT positivity had at least one positive SPT. SIgE>4 kU/L had at least one sIgE above 4 kU/L. SCGB1A1 A38G (rs3741240), that alters gene transcription, was genotyped using Sau96I restriction digestion of exon 1 PCR products.

RESULTS

At 6 and 11 years of age, 33.0% and 29.7% of those genotyped had doctor-diagnosed asthma, and 35.8% and 52.1% had SPT positivity. In cross-sectional analyses, children with 38G/38A or 38A/38A had increased AR at 1 month (1.72-fold, P=0.013); sIgE>4 kU/L [odds ratio (OR)=6.95, 95% confidence interval (CI)=1.35-35.91, P=0.021]; house dust mite (HDM) SPT positivity (OR=7.21, 95% CI=1.09-47.78, P=0.041) and sIgE (4.57-fold, P=0.045) at 6 years; and doctor-diagnosed asthma (OR=3.93, 95% CI=1.24-12.47, P=0.02) and cat SPT positivity (OR=4.34, 95% CI=1.01-18.77, P=0.049) at 11 years. Longitudinal analyses of 6 and 11 years paired data showed that children with 38A/38A had increased persistent sIgE>4 kU/L (OR=11.87, 95% CI=1.97-71.53, P=0.007) and persistent HDM SPT positivity (OR=7.84, 95% CI=1.04-58.92, P=0.045).

CONCLUSION

SCGB1A1 A38G may play a role in the development and persistence of the asthma phenotype in childhood.

Beta2-Adrenoceptor polymorphisms and asthma phenotypes: interactions with passive smoking

The aim of the present study was to assess the effects of possible interactions between beta(2)-adrenoceptor gene polymorphisms and passive smoking on forced expiratory volume in one second (FEV(1)), forced vital capacity (FVC) and exhaled nitric oxide (eNO) in children aged 11 yrs. A cross-sectional analysis of the longitudinal cohort was conducted for associations between beta(2)-adrenoceptor gene polymorphisms and lung function and eNO with regard to passive smoking. Among children exposed to tobacco smoke, those with Arg16 (at least one Arg allele) exhibited lower adjusted mean FEV(1) (2.19 versus 2.38 L) and FVC (2.43 versus 2.64 L) than Gly16 homozygotes. Those with Gln27 (at least one Gln allele) also exhibited a lower adjusted mean FEV(1) relative to Glu27 homozygotes (2.24 versus 2.39 L). Among children with no exposure to smoking, those with Arg16 or Gln27 showed lower adjusted geometric mean eNO levels compared with Gly16 homozygotes (15.4 versus 30.9 ppb) and Glu27 homozygotes (18.0 versus 49.7 ppb). In conclusion, passive smoking had a significant effect on associations between beta(2)-adrenoceptor gene polymorphisms and asthma-related phenotypes, enhancing the relationship between Arg16 and lung function and removing the relationship between Arg16 or Gln27 and exhaled nitric oxide levels.

Association of haplotypes of beta2-adrenoceptor polymorphisms with lung function and airway responsiveness in a pediatric cohort

We evaluated the influence of haplotypes of beta(2)-adrenergic receptor (ADRB2) polymorphisms on lung function and airway responsiveness (AR) in a pediatric cohort recruited before birth and followed up to 11 years of age. The subjects (180) were the participants in a prospective study of lung function and AR. They have been assessed five times (at 1 month, 6 months, 12 months, 6 and 11 years of age) for lung function and AR. The two ADRB2 single nucleotide polymorphisms (SNPs): Arg16Gly and Gln27Glu were genotyped by PCR-RLFP and their haplotypes inferred using the program PHASE. An association between the haplotype arg16gln27 and the prevalence of positive AR was found at age 6 years (P = 0.009). The gly16gln27 haplotype was associated with higher FEV1 (P = 0.015) at age 6 and both higher FEV1 and FVC (P = 0.018 and P = 0.001, respectively) at age 11. In contrast, arg16gln27 was associated with both lower FEV1 and FVC (P = 0.028 and P = 0.011, respectively) at age 11. Children with the gly16gln27 haplotype were less likely to have asthma-ever or doctor-diagnosed asthma at age 11 (OR: 0.38; P = 0.019 and OR: 0.31; P = 0.041, respectively). In conclusion, haplotypes of beta(2)-adrenoceptor polymorphisms are associated with lung function, AR, and asthma susceptibility in childhood.

Polymorphisms in the beta2-adrenoreceptor gene are associated with decreased airway responsiveness

BACKGROUND

There are a number of candidate genes thought to play a role in the development of asthma. Polymorphisms at amino acid positions 16 (arginine to glycine) and 27 (glutamine to glutamic acid) of the beta2-adrenoreceptor (B2AR) gene are known to be functionally relevant and have been associated with more severe forms of asthma, nocturnal asthma and decreased airway responsiveness in asthmatic subjects.

OBJECTIVE

To determine if these polymorphisms contribute to the development of asthma by investigating the associations between the polymorphisms at amino acid positions 16 and 27 of the B2AR gene and asthma-related parameters in a large, phenotypically well-characterized population which was unselected for asthma.

METHODS

Subjects (n = 332) were characterized using physiological assessments, immuno-logical data and information obtained from questionnaire. PCR was used to generate a 229 base pair fragment spanning the mutations of interest. Genotype was determined using allele-specific oligonucleotide hybridization and confirmed in 10% of the samples by direct sequencing. Multivariate analysis of the association between genotype and phenotype was then undertaken.

RESULTS

Homozygotes for Glu27 were significantly less responsive to histamine than Gln27 homozygotes. In addition, Arg16 homozygotes were more likely to 'wheeze during a cold', in comparison with Gly16 homozygotes. However, there was no association between either polymorphism and physician-diagnosed asthma, eczema, skin reactivity to common allergens or total and specific serum IgE levels. The two polymorphisms were found to be in significant linkage disequilibrium.

CONCLUSION

The polymorphism at position 27 was associated with decreased airway responsiveness in the study population and the polymorphism at position 16 was associated with increased wheeze during respiratory infection, but neither was associated with physician-diagnosed asthma or any of the other variables considered.

Association of polymorphisms in the beta2-adrenoreceptor gene with higher levels of parasitic infection

The diminishing incidence of parasitic infection in westernised societies has been suggested to result in an increased prevalance of asthma. Asthma is a polygenic disease and genome screens have shown that genes on chromosome 5q31-33 are strongly linked to the disease. The gene for the beta2-adrenoreceptor is located in this region and two polymorphisms have been identified that result in amino acid changes at positions 16 (ArgGly) and 27 (GlnGlu). To determine whether these polymorphisms influence asthma and parasitic infection, a genotype/phenotype study has been performed on a cohort of 126 children from Coche Island in Venezuela. There is a high incidence of asthma on the island and intestinal helminthiasis is endemic. Genotyping for both polymorphisms was carried out by using the polymerase chain reaction and allele-specific oligonucleotide hybridisation. Genotype frequencies in this cohort were consistent with other studies and both polymorphisms were in significant linkage disequilibrium. Individuals who were homozygous for Arg16 had significantly higher levels of specific IgE to Ascaris lumbricoides (P=0.002), significantly higher A. lumbricoides egg counts (P<0.001) and significantly larger wheal sizes following skin-prick testing with A. lumbricoides allergen (P=0.008). There was no association between either polymorphism and total serum IgE or asthma in this population. A combination of mast cell degranulation and the lung migratory phase of A. lumbricoides larvae may result in bronchoconstriction in infected individuals. These results suggest that the Gly 16 allele confers resistance to high levels of parasitic infection in this population. An alternative explanation for the association is that it may be the result of linkage disequilibrium with other genes in the chromosome 5q31-33 region.

A polymorphism of the CC16 gene is associated with an increased risk of asthma

Several quantitative traits associated with the asthma phenotype have been linked to markers on chromosome 11q13, although the gene responsible has yet to be well established. The gene for Clara cell secretory protein (CC16) is an ideal candidate for involvement in an inherited predisposition to asthma because of its chromosomal location, the role of the CC16 protein in controlling airway inflammation, and differences in levels of the protein between asthmatics and healthy controls. All three CC16 exons were screened in an unselected population of 266 subjects from 76 families and a cohort of 52 severely asthmatic children. A combination of single strand conformational polymorphism (SSCP) analysis, heteroduplex analysis, DNA sequencing, and restriction digestion was used. Mutation detection methods identified an adenine to guanine substitution in the CC16 gene at position 38 (A38G) downstream from the transcription initiation site within the non-coding region of exon 1. In the unselected population, 43.6% were homozygous for the polymorphic sequence (38GG) and 46.2% were heterozygous (38AG). All the asthmatic and unaffected children from both populations were selected for an unmatched case control analysis consisting of 67 asthmatic and 46 unaffected subjects. Those homozygous for the published sequence (38AA) had a 6.9-fold increased risk of developing asthma (p=0.049) and heterozygotes (38AG) a 4.2-fold increased risk (p=0.028). Modelling of genotype as a continuous covariate indicated evidence of a significant linear trend across the three genotypes (odds ratio=2.84 per unit increase in genotype code, p=0.018). These associations were independent of age, gender, and tobacco smoke exposure. These data and the known anti-inflammatory role of CC16 in the respiratory tract suggest that alteration to the gene at position 38 may contribute to asthma.

Association of polymorphisms within the tumour necrosis factor (TNF) genes and childhood asthma

BACKGROUND

Tumour necrosis factor alpha (TNFalpha) is a potent modulator of immune and inflammatory responses, and has been implicated in a variety of autoimmune diseases, including asthma. Increased levels of TNFalpha have been detected in both sputa and bronchoalveolar lavage fluid of asthmatic subjects during acute attacks. Interindividual variation in TNFalpha levels may be genetically determined and polymorphisms within the TNF genes and nearby HLA Class II region have been associated with differences in TNFalpha production.

OBJECTIVE

To investigate the association of differences in asthma-related phenotypes with two biallelic polymorphisms: a G to A substitution at position - 308 of the TNFalpha gene promoter (TNF1 and TNF2 alleles) and an NcoI polymorphism in the first intron of the lymphotoxin alpha gene (LT-alpha*1 and LT-alpha*2 alleles).

METHODS

The regions of interest were amplified from genomic DNA using specific primers and PCR. Dot blot analysis was used for genotyping individuals for the TNFalpha - 308 polymorphism, while restriction enzyme digestion was used for genotyping individuals for the LT-alpha gene NcoI polymorphism. A case-control analysis was then performed on 74 asthmatic and 50 non-asthmatic unrelated children for each polymorphism.

RESULTS

The TNFalpha - 308 TNF1 allele was present at a significantly higher frequency in cases than controls (OR= 2.4, P=0.003), and homozygosity for the TNF1 allele was associated with a fivefold increased risk of physician diagnosed asthma relative to the other genotypes (OR = 5.23, P = 0.004). The LT-alpha*2 allele showed similar associations, including an approximately fivefold higher risk of physician diagnosed asthma for LT-alpha*2 homozygotes (OR = 4.89, P = 0.019). Evidence of a significant linear trend in asthma risk across the three genotypes was found for both polymorphisms.

CONCLUSION

These results suggest an important role for the TNFalpha gene or a linked locus in an inherited asthma diathesis.

Virion protein sequence variation among Australian isolates of turnip yellow mosaic tymovirus

The virion protein genes, and 3' untranslated regions, of six variants of turnip yellow mosaic tymovirus (TYMV) that produced different symptoms in their native host Cardamine robusta and in Chinese cabbage plants, have been sequenced. The sequences have been compared with each other, and with the same region of the pBL-16 clone of the Blue Lake isolate of TYMV. The sequences of the virion protein genes differed by a mean of 1.89% (range 0-2.82%), and the encoded proteins by a mean of 1.71% (range 0-3.17%). The nucleotide differences were confined to the 5'-most 60% of the gene, whereas there were amino acid differences only among residues 12 to 29 and residue 102 (numbered from the N-terminus) of the virion protein involving only hydrophobic residues at the surface of the protein. The amino acid and nucleotide differences between the seven isolates did not correlate with differences in the symptoms they caused, but confirmed earlier estimates of genetic variability in the wild populations of the virus.

Turnip yellow mosaic virus isolates with experimentally produced recombinant virion proteins

The consensus secondary structure of the virion proteins (VPs) of tymoviruses was predicted from their amino acid sequences using a combination of computer methods: profile alignment, hydrophobicity moment and 'PredictProtein'. All methods predicted that they were eight-stranded anti-parallel beta-barrels with two alpha-helical regions. The predicted structure was used to design recombinants of turnip yellow mosaic virus (TYMV) in which selected parts of its VP were replaced with homologous regions of belladonna mottle virus (BeMV) in a cDNA clone encoding the genome of TYMV. Six of ten such recombinants were fully viable and most gave symptoms in Chinese cabbage indistinguishable from those of TYMV, although they did not always infect plants systemically and none infected hosts of BeMV or of other tymoviruses. A TYMV recombinant with the N-terminal part of its VP replaced with the E71 epitope of Plasmodium falciparum was also viable, but others with the same region replaced with the V3 region of the lentivirus human immunodeficiency virus type 1 were not. Epitope analysis of antisera prepared against the virions of parental TYMV and some of the recombinants showed that, although the N terminus of the VP is immunogenically dominant, it is not exposed at the surface of the virion, a finding confirmed by comparing the electrophoretic mobilities of the virions. The recently published structure of the TYMV VP determined by X-ray crystallography confirms the accuracy of the predicted secondary structure of the VP, and hence the utility of the methods used.

Recursive Filter Objective Analysis of Meteorological Fields: Applications to NESDIS Operational Processing

A recursive filter objective analysis method is described. It is a "successive approximation" system with the particular feature of locally varying scaling, making it especially appropriate for dealing with inhomogeneous data. Attention is given to proper treatment of lateral boundaries, which permit its use in limited domains. Thissystem provides estimates of input data quality that can be used for editing datasets before their distribution and for the weighting of data in application by other users, Two- and three-dimensional versions of the analysis operating on a Cartesian grid are used operationally at the National Environmental Satellite and Data InformationService. They are used both in the production of data and for quality control prior to dissemination. Examplesof these applications are given.

Comparison of radiances observed from satellite and aircraft with calculations by using two atmospheric transmittance models

An evaluation of two different atmospheric transmittance models is performed by using radiance data from the high-resolution infraRed Sounder (HIRS) instrument onboard the National Oceanic and Atmospheric Administration's NOAA-9 satellite and the airborne high-resolution interferometer sounder (HIS) instrument. Synthetic radiances have been derived from collocated radiosondes by using the television infrared observation satellite (TIROS) operational vertical sounder (TOVS) operational transmittance model and the fast atmospheric signature code (FASCOD2) line-by-line transmittance model for comparison with the two independent instrument observations. Radiance observations in various spectral channels from the HIRS and HIS instruments along with the synthetic radiances derived from the FASCOD2 and operational TOVS transmittance models are used for the performance evaluation. The results of the comparison reveal a significant discrepancy between 707 and 717 cm(-l) in the radiance calculation for both models. Exce llent agreement is observed between observation and calculation for the lower tropospheric long-wave temperature sounding channels. Serious problems are noted with the modeling of water vapor in the operational TOVS transmittance model. In addition, poor performance by FASCOD2 is revealed for the short-wavelength N(2)O-CO(2) HIRS spectral channels. In general the operational TOVS transmittance model is found to be only slightly inferior to the FASCOD2 model. Regarding the performance of the instruments, observations from the NOAA-9 HIRS and the aircraft HIS are comparable in terms of their agreement with theoretical computations.

The Meteorological Satellite: Overview of 25 Years of Operation

The first weather satellite was launched on 1 April 1960. In the 25 years since, weather satellites have contributed to improved weather analyses and forecasts worldwide. As a maturing component of a global observing system, the meteorological satellite promises even greater financial benefits and a higher quality of life to mankind.

Toxicity and bioaccumulation of cadmium in the colonial green alga Scenedesmus obliquus

A laboratory investigation was conducted to study the extent and efficiency of cadmium bioaccumulation in Scenedesmus obliquus by subjecting this alga to varied sublethal Cd concentrations. The influence of cell population age on Cd bioaccumulation was also studied. Under the experimental conditions employed, growth was not significantly affected by Cd concentrations ranging from 0.01 ppm to 1.00 ppm. At concentrations above 1.00 ppm, however, growth was inhibited markedly. Increases in external Cd concentration caused an increase in total bioaccumulation over the entire range of concentrations, which did not significantly affect growth. Efficiency of Cd bioaccumulation was also concentration dependent, but maximum accumulation efficiency occurred in a medium with a Cd concentration lower than that medium in which maximum total bioaccumulation occurred. Age of the cell population influenced the extent of Cd bioaccumulation. Rapidly growing, young cultures accumulated less Cd than older cultures approaching stationary growth phase.