Progressive Age-Related Changes Similar to Age-Related Macular Degeneration in a Transgenic Mouse Model

Age-related macular degeneration (AMD) is the major cause of blindness in the developed world. its pathomechanism is unknown and its late onset, complex genetics and strong environmental components have all hampered investigations. Here we demonstrate the development of an animal model for AMD that reproduces features associated with geographic atrophy, a transgenic mouse line (mcd/mcd) expressing a mutated form of cathepsin D that is enzymatically inactive thus impairing processing of phagocytosed photoreceptor outer segments in the retinal pigment epithelial (RPE) cells. Pigmentary changes indicating RPE cell atrophy and a decreased response to flash electroretinograms were observed in 11- to 12-month-old mcd/mcd mice. Histological studies showed RPE cell proliferation, photoreceptor degeneration, shortening of photoreceptor outer segments, and accumulation of immunoreactive photoreceptor breakdown products in the RPE cells. An accelerated photoreceptor cell death was detected in 12-month-old mcd/mcd mice. Transmission electron microscopy demonstrated presence of basal laminar and linear deposits that are considered to be the hallmarks of AMD. Small hard drusen associated with human age-related maculopathy were absent in the mcd/mcd mouse model at the ages analyzed. in summary, this model presents several features of AMD, thus providing a valuable tool for investigating the underlying biological processes and pathomechanism of AMD.

Are wing size, wing shape and asymmetry related to field fitness of Trichogramma egg parasitoids?

The effects of wing shape, wing size, and fluctuating asymmetry in these measures oil the field fitness of T. nr. brassicae and T. pretiosum were investigated. Trichogramma wasps mass-reared on eggs of the factitious host Sitotroga cerealella were released in tomato paddocks and those females ovipositing on Helicoverpo spp. eggs were recaptured. Comparisons of the recaptured group with a sample from the release population were used to assess fitness. Wing data were obtained by positioning landmarks on mounted forewings. Size was then measured as the centroid size computed from landmark distances, while Procrustes analysis followed by principal component analysis was used to assess wing shape. Similar findings were obtained for both Trichogramma species: fitness of wasps was strongly related to wing size and some shape dimensions, but not to the asymmetries of these measures. Wasps which performed well in the field had larger wings and a different wing shape compared to wasps from the mass reared population. Both size and the shape dimensions were linearly associated with fitness although there was also some evidence for non-linear selection on shape. The results suggest that wing shape and wing size are reliable predictors of field fitness for these Trichogramma wasps.

Characterization of highly conserved microsatellite loci in Araucaria cunninghamii and related species

Ten microsatellite loci are described in Araucaria cunninghamii, the first reported in the Araucariaceae. Eight were tested in sections Eutacta and Bunya, which diverged more than 200 MYA, and to the sister genus Agathis. Specific amplification products within the expected size range were obtained for six to eight loci in section Eutacta (depending on species), five loci in section Bunya and three. loci in Agathis. Two of the loci (CRCAc1 and CRCAc2, both GA repeats) produced specific amplification products in all taxa, with orthology confirmed by sequence analysis. The repeats were perfect in all taxa. The flanking sequences were extremely conserved, with sequence divergence of 0% to 2.0% within Araucaria species and 2.9% to 7.5% between Araucaria and Agathis. These microsatellites represent some of the most conserved microsatellite loci reported in plants. This may be due to a low evolutionary rate in Araucariaceae genome or the loci may be closely associated with highly conserved, unreported genes.

The VCAM-1 gene that encodes the vascular cell adhesion molecule is a target of the Sry-related high mobility group box gene, Sox18

VCAM-1 (vascular cell adhesion molecule-1) and Sox18 are involved in vascular development. VCAM-1 is an important adhesion molecule that is expressed on endothelial cells and has a critical role in endothelial activation, inflammation, lymphatic pathophysiology, and atherogenesis. The Sry-related high mobility group box factor Sox18 has previously been implicated in endothelial pathologies. Mutations in human and mouse Sox18 leads to hypotrichosis and lymphedema. Furthermore, both Sox18 and VCAM-1 have very similar spatio-temporal patterns of expression, which is suggestive of crosstalk. We use biochemical techniques, cell culture systems, and the ragged opossum (RaOP) mouse model with a naturally occurring mutation in Sox18 to demonstrate that VCAM-1 is an important target of Sox18. Transfection, site-specific mutagenesis, and gel shift analyses demonstrated that Sox18 directly targeted and trans-activated VCAM-1 expression. Importantly, the naturally occurring Sox18 mutant attenuates the expression and activation of VCAM-1 in vitro. Furthermore, in vivo quantitation of VCAM-1 mRNA levels in wild type and RaOP mice demonstrates that RaOP animals show a dramatic and significant reduction in VCAM-1 mRNA expression in lung, skin, and skeletal muscle. Our observation that the VCAM-1 gene is an important target of SOX18 provides the first molecular insights into the vascular abnormalities in the mouse mutant ragged and the human hypotrichosis-lymphedematelangiectasia disorder.

Ovary colonization by Claviceps africana is related to ergot resistance in male-sterile sorghum lines

Ergot, caused by Claviceps africana, has emerged as a serious threat to sorghum hybrid seed production worldwide. In the absence of gene-for-gene-based qualitative resistance in commercial cultivars, varieties with high pollen production that can escape ergot infection are preferred. Recent demonstration of differences in ergot susceptibility among male-sterile lines has indicated the presence of partial resistance. Using chitin-specific fluorescin-isothiocyanate-conjugated wheat germ agglutin and callose-specific aniline blue, this study investigated the process of sorghum ovary colonization by C. africana. Conidia germinated within 24 h after inoculation (a.i.); the pathogen was established in the ovary by 79 h a.i., and at least half of the ovary was converted into sphacelial tissue by 120 h a.i. Changes in fungal cell wall chitin content and strategic callose deposition in the host tissue were associated with penetration and invasion of the ovary. The rate of ovary colonization differed in three male-sterile lines that also differed in ergot susceptibility. This work demonstrates a possible histological basis for partial resistance in male-sterile sorghum lines that could lay the foundation for variety improvement through further breeding and selection.

Issues related to the wearing of fall-arrest harnesses in the construction industry

Work-related falls continues to be one of the leading causes of fatalities in the Australian construction industry, and the failure to use fall protection equipment, such as fall-arrest harnesses and arresting devices, has been found to be a contributing factor. In an attempt to gain an understanding of the issues surrounding the use of fallarrest harness systems by construction workers a study involving semi-structured interviews of 15 male construction workers was carried out at three construction sites. The majority of interviewees commented that there was discomfort in wearing a fall-arrest harness; that there were a number of problems when anchored via an arresting device; and that using a fall-arrest system reduced productivity. Most of the interviewees considered that they needed safety precautions against falls, and they expressed the view that workers’ attitudes towards safety depended critically upon their supervisors’ attitude towards safety. It was also found that workers were not trained in rescue procedures. Interviewees expressed concern that retrieval of a suspended worker may not be carried out in time to prevent the onset of suspension trauma. A number of issues were identified which require further research, such as, investigation into suspension trauma, harness and arresting device design, training provided to workers, and the provision for rescues.

Identification of residues which regulate activity of the STE20-related kinase hMINK

Activity of the STE20-related kinase hMINK was investigated. hMINK was expressed widely, though not ubiquitously, in human tissues: highest levels being found in haematopoietic tissues but also in brain, placenta, and lung. Mutagenesis revealed that T-191. and Y-193 in the substrate recognition loop of the catalytic domain were critical for kinase activity against exogenous substrates and autophosphorylation. A mutation on T-187 showed reduced enzymatic activity against exogenous substrates but retained autophosphorylationactivity. Phosphorylation was confirmed by the use of a phospho-specific T-187 antibody. hMINK activated the JNK signal transduction pathway and optimal JNK activation occurred when the C-terminus was deleted. In addition, overexpression of the C-terminal domain devoid of kinase activity also resulted in significant activation of the JNK pathway. These data suggest that hMINK requires an activation step that dissociates the C terminal, thereby freeing the catalytic domain to interact with substrates. Models for receptor-mediated activation of hMINK are discussed. (C) 2002 Elsevier Science (USA). All rights reserved.

Physiological responses to repeated bouts of high-intensity ultraendurance cycling - a field study case report

The present study aimed to 1) examine the relationship between laboratory-based measures and high-intensity ultraendurance (HIU) performance during an intermittent 24-h relay ultraendurance mountain bike race (similar to20 min cycling, similar to60min recovery), and 2) examine physiological and performance based changes throughout the HIU event. Prior to the HIU event, four highly-trained male cyclists (age = 24.0 +/- 2.1 yr; mass = 75.0 +/- 2.7 kg; (V)over dot O-2peak = 70 +/- 3 ml.kg(-1).min(-1)) performed 1) a progressive exercise test to determine peak Volume of oxygen uptake ((V)over dot O-2peak), peak power output (PPO), and ventilatory threshold (T-vent), 2) time-to-fatigue tests at 100% (TF100) and 150% of PPO (TF150), and 3) a laboratory simulated 40-km time trial (TT40). Blood lactate (Lac(-)), haematocrit and haemoglobin were measured at 6-h intervals throughout the HIU event, while heart rate (HR) was recorded continuously. Intermittent HIU performance, performance HR, recovery HR, and Lac declined (P < 0.05), while plasma volume expanded (P < 0.05) during the HIU event. TF100 was related to the decline in lap time (r = -0.96; P < 0.05), and a trend (P = 0.081) was found between TF150 and average intermittent HIU speed (r = 0.92). However, other measures (V)over dot O-2peak, PPO, T-vent, and TT40) were not related to HIU performance. Measures of high-intensity endurance performance (TF100, TF150) were better predictors of intermittent HIU performance than traditional laboratory-based measures of aerobic capacity.

Differences in lung function, growth parameters and frequency of hospital admissions between adolescents with cystic fibrosis-related diabetes and controls

As survival of patients with CF increases,glucose intolerance and cystic fibrosisrelated diabetes (CFRD),ar e increasingly recognised common complications. CFRD may be preceded by a pre-diabetic state. Using markers identified as being associated with CFRD may improve targeted screening. Aim: To identify features consistently predicting CFRD in paediatric patients. Patients diagnosed with CFRD between January 1997–January 2002 were compared with age and sex matched controls. Clinical,micr obiological, and hospitalisation data was collected at time of CFRD diagnosis,and at six monthly intervals for 3 yr prior to diagnosis. Eight patients with CFRD were identified,mean age 13.7 yr (S.D. 3.49) at time of diagnosis. Control patients underwent OGTT to ensure normal glucose tolerance. Patients with CFRD had a lower FEV1 up to 12 months prior to diagnosis however, this was only significant at diagnosis. There was no difference in weight and height z scores between the 2 groups; however,the decrease in weight and height z scores in the CFRD group over 3 yr prior to diagnosis was significant. Mean number of days in hospital and admissions per patient significantly increased in the CFRD group,6 months prior to diagnosis. No other significant differences were observed between the 2 groups. Conclusions: This study has shown a difference in lung function,gr owth parameters and frequency of hospital admissions between patients with CFRD and controls. These differences may be utilised as tools for targeted screening in the paediatricyadolescent population. Further larger scale studies are required to improve guidelines for targeted screening in this population.

Isolation and characterization of a cone snail protease with homology to CRISP proteins of the pathogenesis-related protein superfamily

The pathogenesis-related (PR) protein superfamily is widely distributed in the animal, plant, and fungal kingdoms and is implicated in human brain tumor growth and plant pathogenesis. The precise biological activity of PR proteins, however, has remained elusive. Here we report the characterization, cloning and structural homology modeling of Tex31 from the venom duct of Conus textile. Tex31 was isolated to >95% purity by activity-guided fractionation using a para-nitroanilide substrate based on the putative cleavage site residues found in the propeptide precursor of conotoxin TxVIA. Tex31 requires four residues including a leucine N-terminal of the cleavage site for efficient substrate processing. The sequence of Tex31 was determined using two degenerate PCR primers designed from N-terminal and tryptic digest Edman sequences. A BLAST search revealed that Tex31 was a member of the PR protein superfamily and most closely related to the CRISP family of mammalian proteins that have a cysteine-rich C-terminal tail. A homology model constructed from two PR proteins revealed that the likely catalytic residues in Tex31 fall within a structurally conserved domain found in PR proteins. Thus, it is possible that other PR proteins may also be substrate-specific proteases.

Poor correlation of mid-femoral measurements by CT and hip measurements by DXA in the elderly

Background and aims: Hip fracture is a devastating event in terms of outcome in the elderly, and the best predictor of hip fracture risk is hip bone density, usually measured by dual X-ray absorptiometry (DXA). However, bone density can also be ascertained from computerized tomography (CT) scans, and mid-thigh scans are frequently employed to assess the muscle and fat composition of the lower limb. Therefore, we examined if it was possible to predict hip bone density using mid-femoral bone density. Methods: Subjects were 803 ambulatory white and black women and men, aged 70-79 years, participating in the Health, Aging and Body Composition (Health ABC) Study. Bone mineral content (BMC, g) and volumetric bone mineral density (vBMD, mg/cm(3)) of the mid-femur were obtained by CT, whereas BMC and areal bone mineral density (aBMD, g/cm(2)) of the hip (femoral neck and trochanter) were derived from DXA. Results: In regression analyses stratified by race and sex, the coefficient of determination was low with mid-femoral BMC, explaining 6-27% of the variance in hip BMC, with a standard error of estimate (SEE) ranging from 16 to 22% of the mean. For mid-femur vBMD, the variance explained in hip aBMD was 2-17% with a SEE ranging from 15 to 18%. Adjusting aBMD to approximate volumetric density did not improve the relationships. In addition, the utility of fracture prediction was examined. Forty-eight subjects had one or more fractures (various sites) during a mean follow-up of 4.07 years. In logistic regression analysis, there was no association between mid-femoral vBMD and fracture (all fractures), whereas a 1 SD increase in hip BMD was associated with reduced odds for fracture of similar to60%. Conclusions: These results do not support the use of CT-derived mid-femoral vBMD or BMC to predict DXA-measured hip bone mineral status, irrespective of race or sex in older adults. Further, in contrast to femoral neck and trochanter BMD, mid-femur vBMD was not able to predict fracture (all fractures). (C) 2003, Editrice Kurtis.

Sex- and race-related differences in cross-sectional geometry and bone density of the femoral mid-shaft in older adults

Background : Femoral shaft fracture incidence increases in older adults and is associated with low-energy trauma. Apart from bone density, the distribution and size of bone contributes to its strength. Aim : To examine if bone geometry and density of the femoral mid-shaft in older adults differs by sex and race, we studied 197 White women, 225 Black women, 242 White men, and 148 Black men aged 70-79 years participating in the Health, Aging, and Body Composition study; a prospective cohort study in the USA. A secondary purpose of the study was to examine the association of site-specific muscle and fat to bone geometry and density. Subjects and methods : Subjects were community-dwelling and reported no difficulty walking one-quarter of a mile or climbing stairs. Mid-femoral volumetric bone mineral density (vBMD, mg cm -3 ), total area (TA), cortical area (CA), medullary area (MA), cross-sectional moments of inertia (CSMI: I x , I y , J ), and muscle and fat areas (cm 2 ) were determined by computed tomography (CT; GE CT-9800, 10 mm slice thickness). Results : vBMD was greater in men than women with no difference by race ( p < 0.001). Bone areas and area moments of inertia were also greater in men than women ( p < 0.001), with Black women having higher values than White women for TA and CA. Standardizing geometric parameters for body size differences by dividing by powers of femur length did not negate the sex difference for TA and MA. Significant differences ( p < 0.05) among the four groups also remained for I x and J . Mid-thigh muscle area was an independent contributor to TA in all groups (Std beta = 0.181-0.351, p < 0.05) as well as CA in women (Std beta = 0.246-0.254, p < 0.01) and CSMI in White women (Std beta = 0.175-0.185, p < 0.05). Further, muscle area was a significant contributor to vBMD in Black women. Conclusion : These results indicate that bone geometry and density of the femoral diaphysis differs primarily by sex, rather than race, in older well-functioning adults. In addition, site-specific muscle area appears to have a potential contributory role to bone geometry parameters, especially in women.