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Similar Defect (similar + defect)
Selected AbstractsHush Puppy: A New Mouse Mutant With Pinna, Ossicle, and Inner Ear Defects,THE LARYNGOSCOPE, Issue 1 2005FRCSEd, Henry Pau MD Abstract Objectives/Hypothesis: Deafness can be associated with abnormalities of the pinna, ossicles, and cochlea. The authors studied a newly generated mouse mutant with pinna defects and asked whether these defects are associated with peripheral auditory or facial skeletal abnormalities, or both. Furthermore, the authors investigated where the mutation responsible for these defects was located in the mouse genome. Methods: The hearing of hush puppy mutants was assessed by Preyer reflex and electrophysiological measurement. The morphological features of their middle and inner ears were investigated by microdissection, paint-filling of the labyrinth, and scanning electron microscopy. Skeletal staining of skulls was performed to assess the craniofacial dimensions. Genome scanning was performed using microsatellite markers to localize the mutation to a chromosomal region. Results: Some hush puppy mutants showed early onset of hearing impairment. They had small, bat-like pinnae and normal malleus but abnormal incus and stapes. Some mutants had asymmetrical defects and showed reduced penetrance of the ear abnormalities. Paint-filling of newborns' inner ears revealed no morphological abnormality, although half of the mice studied were expected to carry the mutation. Reduced numbers of outer hair cells were demonstrated in mutants' cochlea on scanning electron microscopy. Skeletal staining showed that the mutants have significantly shorter snouts and mandibles. Genome scan revealed that the mutation lies on chromosome 8 between markers D8Mit58 and D8Mit289. Conclusion: The study results indicate developmental problems of the first and second branchial arches and otocyst as a result of a single gene mutation. Similar defects are found in humans, and hush puppy provides a mouse model for investigation of such defects. [source] Abstract no.: 6 Endothelium-dependent relaxation by purinergic receptors in the aorta of apolipoprotein E-deficient miceFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2005A. Korda Previously we reported that the acetylcholine-induced relaxation in the isolated aorta of apolipoprotein E-deficient (apoE -/- ) mice deteriorates after the development of atherosclerotic plaques, but remains normal in adjacent, plaque-free segments. The present study investigated the presence of functional purinergic receptors in the murine aorta, and whether their function changes before or after the development of atherosclerosis. Endothelium-dependent relaxation was measured in aorta segments of apoE -/- , C57BL6 (WT) and human apoAI-overexpressing apoE -/- mice (apoAI/apoE -/- ) on regular chow. Rings were isometrically contracted with phenylephrine to 50% of their maximum force before performing cumulative concentration-response curves to different nucleotides or their stable analogues. After the functional study, the cross-sectional area of the plaque was determined in every segment. The nucleotides induced complete (UTP, UDP, ATP) or partial (ADP) relaxation that was abolished by endothelial cell removal or nitric oxide (NO) synthase inhibition. The responses pointed to the presence of functional P2y1, P2y2 or P2y4 receptors on endothelial cells. RT-PCR confirmed the presence of P2y1 and P2y4 mRNA in the aorta of WT mice. Nucleotide responses were unaltered in lesion-free apoE -/- mice (5 months). However, in atherosclerotic segments of apoE -/- mice (18 months), the relaxation to ATP was impaired compared to age-matched WT controls (maximum amplitude (Emax) 25 ± 14%, n = 6 vs. 90 ± 3%, n = 5, P < 0.01). A similar defect was seen for the stable analogue ATP-gamma-S (Emax 36 ± 12% vs. 86 ± 3%, P < 0.01). Atherosclerotic apoE -/- segments were less sensitive to the NO donor spermineNONOate (pD2 6.74 ± 0.18) than WT segments (7.25 ± 0.20), but maximum relaxation was unaltered. In non-atherosclerotic aorta segments of the same apoE -/- mice all relaxation responses remained normal and were not different from WT. Strong negative correlations (P < 0.001) existed between lesion size and the Emax for ATP (rs = ,0.82) and ATP-gamma-S (rs = ,0.73) in apoE -/- mice. ApoAI overexpression improved the purinergic responses (Emax ATP 64 ± 9%, ATP-gamma-S 64 ± 10%, n = 5) and these were not different from WT (P > 0.05). An analysis of covariance with plaque size as covariate suggested that this benefit was secondary to the strongly reduced plaque formation in apoAI/apoE -/- mice. It is concluded that functional P2 y receptors are present on murine aortic endothelium. Furthermore, endothelium-dependent purinergic relaxation declines after plaque development. This deterioration involves decreased bioavailability of NO rather than enhanced ATP degradation. The defect is, however, not systemic since the responses remain unaltered in plaque-free segments of atherosclerosis-prone apoE -/- mice. [source] Genetic Analysis of ele Mutants and Comparative Mapping of ele1 Locus in the Control of Organ Internal Asymmetry in Garden PeaJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 6 2010Xin Li Previous study has shown that during zygomorphic development in garden pea (Pisum sativum L.), the organ internal (IN) asymmetry of lateral and ventral petals was regulated by a genetic locus, SYMMETRIC PETAL 1 (SYP1), while the dorsoventral (DV) asymmetry was determined by two CYC - like TCP genes or the PsCYC genes, KEELED WINGS (K) and LOBED STANDARD 1 (LST1). In this study, two novel loci, ELEPHANT EAR-LIKE LEAF 1 (ELE1) and ELE2 were characterized. These mutants exhibit a similar defect of IN asymmetry as syp1 in lateral and ventral petals, but also display pleiotropic effects of enlarged organ size. Genetic analysis showed that ELE1 and ELE2 were involved in same genetic pathway and the enlarged size of petals but not compound leaves in ele2 was suppressed by introducing k and lst1, indicating that the enlargement of dorsal petal in ele2 requires the activities of K and LST1. An experimental framework of comparative genomic mapping approach was set up to map and clone LjELE1 locus in Lotus japonicus. Cloning the ELE1 gene will shed light on the underlying molecular mechanism during zygomorphic development and further provide the molecular basis for genetic improvement on legume crops. [source] Adverse endothelial function and the insulin resistance syndromeJOURNAL OF INTERNAL MEDICINE, Issue 4 2000J. E. Tooke Abstract. Tooke JE, Hannemann MM (School of Postgraduate Medicine and Vascular Health Sciences, University of Exeter, Devon). Adverse endothelial function and the insulin resistance syndrome (Review). J Intern Med 2000; 247: 425,431. Type 2 diabetes is characterized by impaired endothelial dependent vasodilatation which may contribute to the high prevalence of vascular disease in such patients. Although hyperglycaemia, dyslipidaemia and hypertension can all independently cause a similar defect, recent data suggest that endothelial dysfunction may be intrinsic to the insulin resistance syndrome that commonly precedes type 2 diabetes. Such abnormalities in endothelial function could represent the impact of subclinical disturbance of metabolism or alternatively the presence of a common cellular defect that influences both nitric oxide bioavailability and insulin mediated glucose disposal. Resolution of this puzzle is likely to lead to important advances in our knowledge and ultimately treatment of vascular disease. [source] Introduction to Flap Movement: Reconstruction of Five Similar Nasal Defects Using Different FlapsDERMATOLOGIC SURGERY, Issue 2005Elbert H. Chen MD Background. There are several options for closure of a given surgical defect after tumor extirpation is confirmed. Flap reconstruction is one of these options. Objective. The purpose of this article is to introduce the three basic types of flap movement: advancement, rotation, and transposition. Methods. Five similar defects located on the nasal sidewall were repaired, each using a different flap design. Results. The optimal flap design for a given defect on a particular patient is based on the answers to a series of questions: Where is the available tissue reservoir? How can tissue be mobilized from the reservoir to cover the defect? How do the resulting tension vectors affect critical structures? Where are the final incision lines? Conclusion. Many factors must be evaluated before determining a method of reconstruction. Flap reconstruction requires a thorough understanding of anatomy and tissue movement. [source] Anomalous Defects and Dynamic Failure of Armor CeramicsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2004M.P. Bakas The ballistic performance of state-of-the-art silicon carbide armor material can exhibit a fairly wide variability in certain test configurations, which, it is proposed, may be due to the presence of large (>0.1 mm), rare defects, termed, herein, "anomalous" defects. SiC rubble resulting from ballistic tests was examined, as were quasi-static test samples. Ballistic fragment fracture surfaces revealed large carbonaceous defects that seemed to affect fracture path and mode. Low-strength biaxial flexure samples demonstrated similar defects (>0.1 mm) as failure origins. Carbonaceous defects similar in appearance but smaller in size were also found at the fracture origins of SiC bend bars. Frequently, alumina inclusions were found within the carbonaceous discontinuities. These alumina inclusions may cause the graphitic regions to form during sintering. The random distribution of such large, rare carbonaceous discontinuities from sample-to-sample, as well as batch-to-batch variability, may explain high ballistic variability for SiC armor ceramics. [source] The maize Viviparous10/Viviparous13 locus encodes the Cnx1 gene required for molybdenum cofactor biosynthesisTHE PLANT JOURNAL, Issue 2 2006Timothy G. Porch Summary Abscisic acid (ABA), auxin and nitrate are important signaling molecules that affect plant growth responses to the environment. The synthesis or metabolism of these compounds depends on the molybdenum cofactor (MoCo). We show that maize (Zea mays) viviparous10 (vp10) mutants have strong precocious germination and seedling lethal phenotypes that cannot be rescued with tissue culture. We devised a novel PCR-based method to clone a transposon-tagged allele of vp10, and show that Vp10 encodes the ortholog of Cnx1, which catalyzes the final common step of MoCo synthesis. The seedling phenotype of vp10 mutants is consistent with disruptions in ABA and auxin biosynthesis, as well as a disruption in nitrate metabolism. Levels of ABA and auxin are reduced in vp10 mutants, and vp10 seedlings lack MoCo-dependent enzyme activities that are repairable with exogenous molybdenum. vp10 and an Arabidopsis cnx1 mutant, chlorate6 (chl6), have similar defects in aldehyde oxidase (AO) enzyme activity, which is required for ABA synthesis. Surprisingly, chl6 mutants do not show defects in abiotic stress responses. These observations confirm an orthologous function for Cnx1 and Vp10, as well as defining a characteristic viviparous phenotype to identify other maize cnx mutants. Finally, the vp10 mutant phenotype suggests that cnx mutants can have auxin- as well as ABA-biosynthesis defects, while the chl6 mutant phenotype suggests that low levels of AO activity are sufficient for normal abiotic stress responses. [source] | |||||||||||||