Home About us Contact
|
Home About us Contact | ||
|
|
||
OI
Terms modified by OI Selected AbstractsNo effect of venoconstrictive thigh cuffs on orthostatic hypotension induced by head-down bed restACTA PHYSIOLOGICA, Issue 2 2000M.-A. Custaud Orthostatic intolerance (OI) is the most serious symptom of cardiovascular deconditioning induced by head-down bed rest or weightlessness. Wearing venoconstrictive thigh cuffs is an empirical countermeasure used by Russian cosmonauts to limit the shift of fluid from the lower part of the body to the cardio-cephalic region. Our aim was to determine whether or not thigh cuffs help to prevent orthostatic hypotension induced by head-down bed rest. We studied the effect of thigh cuffs on eight healthy men. The cuffs were worn during the day for 7 days of head-down bed rest. We measured: orthostatic tolerance (stand tests and lower body negative pressure tests), plasma volume (Evans blue dilution), autonomic influences (plasma noradrenaline) and baroreflex sensitivity (spontaneous baroreflex slope). Thigh cuffs limited the loss of plasma volume (thigh cuffs: ,201 ± 37 mL vs. control: ,345 ± 42 mL, P < 0.05), the degree of tachycardia and reduction in the spontaneous baroreflex sensitivity induced by head-down bed rest. However, the impact of thigh cuffs was not sufficient to prevent OI (thigh cuffs: 7.0 min of standing time vs. control: 7.1 min). Decrease in absolute plasma volume and in baroreflex sensitivity are known to be important factors in the aetiology of OI induced by head-down bed rest. However, dealing with these factors, using thigh cuffs for example, is not sufficient to prevent OI. Other factors such as venous compliance, microcirculatory changes, peripheral arterial vasoconstriction and vestibular afferents must also be considered. [source] Egg maturation strategy and its associated trade-offs: a synthesis focusing on LepidopteraECOLOGICAL ENTOMOLOGY, Issue 4 2005Mark A. Jervis Abstract., 1.,Insects vary considerably between and within orders, and even within the same genus, in the degree to which the female's lifetime potential egg complement is mature when she emerges as an adult. 2.,The ,ovigeny index' (OI) , the number of eggs females have ready to lay divided by the lifetime potential fecundity , quantifies variation in the degree of early life concentration of egg production, and also variation in initial reproductive effort. 3.,Here, an integrated set of hypotheses is presented, based on a conceptual model of resource allocation and acquisition, concerning trade-offs at the interspecific level between initial investment in egg production (as measured by OI) and other life-history traits in holometabolous insects. 4.,The evidence supporting each of these hypotheses is reviewed, and particular attention is paid to the Lepidoptera, as relevant life-history data are rapidly accumulating for this ecologically and economically important group. 5.,There is evidence at the interspecific level supporting: (i) a link between OI and a trade-off between soma and non-soma in Trichoptera and Hymenoptera (the proportionate allocation to soma decreases with increasing OI); (ii) a negative correlation between OI and dependency on external nutrient inputs (via adult feeding) in Hymenoptera and in Lepidoptera; (iii) a negative correlation between OI and the degree of polyandry (and nuptial gift, i.e. spermatophore, use) in Lepidoptera; (iv) negative correlations between OI and resource re-allocation capabilities (egg and thoracic musculature resorption) in Hymenoptera and in Lepidoptera; (v) a negative correlation between lifespan and OI in Trichoptera, Hymenoptera, and Lepidoptera, indicating a cost of reproduction; (vi) a link between winglessness and an OI of one in Lepidoptera; (vii) a negative correlation between OI and the degree of female mobility in winged Lepidoptera; and (viii) a negative correlation between OI and larval diet breadth (as mediated by oviposition strategy) in Lepidoptera. [source] A new metric for evaluating the correspondence of spatial patterns in vegetation modelsGLOBAL ECOLOGY, Issue 4 2008Guoping Tang ABSTRACT Aim, To present a new metric, the ,opposite and identity' (OI) index, for evaluating the correspondence between two sets of simulated time-series dynamics of an ecological variable. Innovation, The OI index is introduced and its mathematical expression is defined using vectors to denote simulated variations of an ecological variable on the basis of the vector addition rule. The value of the OI index varies from 0 to 1 with a value 0 (or 1) indicating that compared simulations are opposite (or identical). An OI index with a value near 0.5 suggests that the difference in the amplitudes of variations between compared simulations is large. The OI index can be calculated in a grid cell, for a given biome and for time-series simulations. The OI indices calculated in each grid cell can be used to map the spatial agreement between compared simulations, allowing researchers to pinpoint the extent of agreement or disagreement between two simulations. The OI indices calculated for time-series simulations allow researchers to identify the time at which one simulation differs from another. A case study demonstrates the application and reliability of the OI index for comparing two simulated time-series dynamics of terrestrial net primary productivity in Asia from 1982 to 2000. In the case study, the OI index performs better than the correlation coefficient at accurately quantifying the agreement between two simulated time-series dynamics of terrestrial net primary productivity in Asia. Main conclusions, The OI index provides researchers with a useful tool and multiple flexible ways to compare two simulation results or to evaluate simulation results against observed spatiotemporal data. The OI index can, in some cases, quantify the agreement between compared spatiotemporal data more accurately than the correlation coefficient because of its insensitivity to influential data and outliers and the autocorrelation of simulated spatiotemporal data. [source] Y-position cysteine substitution in type I collagen (,1(I) R888C/p.R1066C) is associated with osteogenesis imperfecta/Ehlers-Danlos syndrome phenotype,,HUMAN MUTATION, Issue 4 2007Wayne A. Cabral Abstract The most common mutations in type I collagen causing types II,IV osteogenesis imperfecta (OI) result in substitution for glycine in a Gly-Xaa-Yaa triplet by another amino acid. We delineated a Y-position substitution in a small pedigree with a combined OI/Ehlers-Danlos Syndrome (EDS) phenotype, characterized by moderately decreased DEXA z-score (,1.3 to ,2.6), long bone fractures, and large-joint hyperextensibility. Affected individuals have an ,1(I)R888C (p.R1066C) substitution in one COL1A1 allele. Polyacrylamide gel electrophoresis (PAGE) of [3H]-proline labeled steady-state collagen reveals slight overmodification of the ,1(I) monomer band, much less than expected for a substitution of a neighboring glycine residue, and a faint ,1(I) dimer. Dimers form in about 10% of proband type I collagen. Dimer formation is inefficient compared to a possible 25%, probably because the SH-side chains have less proximity in this Y-position than when substituting for a glycine. Theoretical stability calculations, differential scanning calorimetry (DSC) thermograms, and thermal denaturation curves showed only weak local destabilization from the Y-position substitution in one or two chains of a collagen helix, but greater destabilization is seen in collagen containing dimers. Y-position collagen dimers cause kinking of the helix, resulting in a register shift that is propagated the full length of the helix and causes resistance to procollagen processing by N-proteinase. Collagen containing the Y-position substitution is incorporated into matrix deposited in culture, including immaturely and maturely cross-linked fractions. In vivo, proband dermal fibrils have decreased density and increased diameter compared to controls, with occasional aggregate formation. This report on Y-position substitutions in type I collagen extends the range of phenotypes caused by nonglycine substitutions and shows that, similar to X- and Y-position substitutions in types II and III collagen, the phenotypes resulting from nonglycine substitutions in type I collagen are distinct from those caused by glycine substitutions. Hum Mutat 28(4), 396,405, 2007. Published 2007 Wiley-Liss, Inc. [source] Consortium for osteogenesis imperfecta mutations in the helical domain of type I collagen: regions rich in lethal mutations align with collagen binding sites for integrins and proteoglycans,,HUMAN MUTATION, Issue 3 2007Joan C. Marini Abstract Osteogenesis imperfecta (OI) is a generalized disorder of connective tissue characterized by fragile bones and easy susceptibility to fracture. Most cases of OI are caused by mutations in type I collagen. We have identified and assembled structural mutations in type I collagen genes (COL1A1 and COL1A2, encoding the pro,1(I) and pro,2(I) chains, respectively) that result in OI. Quantitative defects causing type I OI were not included. Of these 832 independent mutations, 682 result in substitution for glycine residues in the triple helical domain of the encoded protein and 150 alter splice sites. Distinct genotype,phenotype relationships emerge for each chain. One-third of the mutations that result in glycine substitutions in ,1(I) are lethal, especially when the substituting residues are charged or have a branched side chain. Substitutions in the first 200 residues are nonlethal and have variable outcome thereafter, unrelated to folding or helix stability domains. Two exclusively lethal regions (helix positions 691,823 and 910,964) align with major ligand binding regions (MLBRs), suggesting crucial interactions of collagen monomers or fibrils with integrins, matrix metalloproteinases (MMPs), fibronectin, and cartilage oligomeric matrix protein (COMP). Mutations in COL1A2 are predominantly nonlethal (80%). Lethal substitutions are located in eight regularly spaced clusters along the chain, supporting a regional model. The lethal regions align with proteoglycan binding sites along the fibril, suggesting a role in fibril,matrix interactions. Recurrences at the same site in ,2(I) are generally concordant for outcome, unlike ,1(I). Splice site mutations comprise 20% of helical mutations identified in OI patients, and may lead to exon skipping, intron inclusion, or the activation of cryptic splice sites. Splice site mutations in COL1A1 are rarely lethal; they often lead to frameshifts and the mild type I phenotype. In ,2(I), lethal exon skipping events are located in the carboxyl half of the chain. Our data on genotype,phenotype relationships indicate that the two collagen chains play very different roles in matrix integrity and that phenotype depends on intracellular and extracellular events. Hum Mutat 28(3), 209,221, 2007. Published 2006 Wiley-Liss, Inc. [source] Intravenous Bisphosphonate Therapy Increases Radial Width in Adults With Osteogenesis Imperfecta,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2005Davide Gatti Abstract Neridronate therapy in adult patients with OI significantly increases the cross-sectional area of the proximal radius. This observation may provide an additional explanation for the antifracture efficacy of bisphosphonates. Introduction: Bisphosphonate therapy decreases by 70-90% the fracture risk in patients with osteogenesis imperfecta (OI). This decrease is somewhat greater than that expected from the BMD changes, supporting the hypothesis that bisphosphonate therapy is associated with structural changes, not detectable by BMD measurements. Materials and Methods: To explore this hypothesis, pQCT measurements at the nondominant radius were obtained in a group of adult OI patients participating in a randomized clinical trial with neridronate. Results: The total volumetric BMD of the ultradistal radius rose significantly in patients treated with neridronate and calcium + vitamin D (neridronate group) compared with patients treated with calcium + vitamin D alone (control group). No significant differences were observed in trabecular BMD and in volumetric cortical density in either group. In the neridronate group, the cross-sectional area rose significantly versus both baseline values and the control group. These latter changes were associated with ,20% increases in bending breaking resistance index (BBRI). Conclusion: Our observation, if extended to postmenopausal osteoporosis, may provide a new explanation for the fracture risk reduction observed in osteoporotic patients treated with bisphosphonates. [source] Positive Linear Growth and Bone Responses to Growth Hormone Treatment in Children With Types III and IV Osteogenesis Imperfecta: High Predictive Value of the Carboxyterminal Propeptide of Type I Procollagen,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2003Joan C Marini MD Abstract Extreme short stature is a cardinal feature of severe osteogenesis imperfecta (OI), types III and IV. We conducted a treatment trial of growth hormone in children with OI and followed linear growth velocity, bone metabolism markers, histomorphometrics, and vertebral bone density. Twenty-six children with types III and IV OI, ages 4.5,12 years, were treated with recombinant growth hormone (rGH), 0.1,0.2 IU/kg per day for 6 days/week, for at least 1 year. Length, insulin-like growth factor (IGF-I), insulin-like growth factor binding protein (IGFBP-3), bone metabolic markers, and vertebral bone density by DXA were evaluated at 6-month intervals. An iliac crest biopsy was obtained at baseline and 12 months. Approximately one-half of the treated OI children sustained a 50% or more increase in linear growth over their baseline growth rate. Most responders (10 of 14) had moderate type IV OI. All participants had positive IGF-I, IGFBP-3, osteocalcin, and bone-specific alkaline phosphatase responses. Only the linear growth responders had a significant increase in vertebral DXA z-score and a significant decrease in long bone fractures. After 1 year of treatment, responders' iliac crest biopsy showed significant increases in cancellous bone volume, trabecular number, and bone formation rate. Responders were distinguished from nonresponders by higher baseline carboxyterminal propeptide (PICP) values (p < 0.05), suggesting they have an intrinsically higher capacity for collagen production. The results show that growth hormone can cause a sustained increase in the linear growth rate of children with OI, despite the abnormal collagen in their bone matrix. In the first year of treatment, growth responders achieve increased bone formation rate and density, and decreased fracture rates. The baseline plasma concentration of PICP was an excellent predictor of positive response. [source] Canine COL1A2 Mutation Resulting in C-Terminal Truncation of Pro-,2(I) and Severe Osteogenesis ImperfectaJOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2001Bonnie G. Campbell Abstract RNA and type I collagen were analyzed from cultured skin fibroblasts of a Beagle puppy with fractures consistent with type III osteogenesis imperfecta (OI). In a nonisotopic RNAse cleavage assay (NIRCA), the proband's RNA had a unique cleavage pattern in the region of COL1A2 encoding the C-propeptide. DNA sequence analyses identified a mutation in which nucleotides 3991-3994 ("CTAG") were replaced with "TGTCATTGG." The first seven bases of the inserted sequence were identical to nucleotides 4002-4008 of the normal canine COL1A2 sequence. The resulting frameshift changed 30 amino acids and introduced a premature stop codon. Reverse-transcription polymerase chain reaction (RT-PCR) with primers flanking the mutation site amplified two complementary DNA (cDNA) fragments for the proband and a single product for the control. Restriction enzyme digestions also were consistent with a heterozygous mutation in the proband. Type I procollagen labeled with [3H]proline was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Increased density of pC-,2(I) suggested comigration with the similarly sized pro-,2(I) derived from the mutant allele. Furthermore, ,-chains were overhydroxylated and the ratio of ,1(I):,2(I) was 3.2:1, consistent with the presence of ,1(I) homotrimers. Analyses of COL1A2 and type I collagen were both consistent with the described heterozygous mutation affecting the pro-,2(I) C-propeptide and confirmed a diagnosis of OI. [source] Type V Osteogenesis Imperfecta: A New Form of Brittle Bone Disease,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2000Francis H. Glorieux Abstract Osteogenesis imperfecta (OI) is commonly subdivided into four clinical types. Among these, OI type IV clearly represents a heterogeneous group of disorders. Here we describe 7 OI patients (3 girls), who would typically be classified as having OI type IV but who can be distinguished from other type IV patients. We propose to call this disease entity OI type V. These children had a history of moderate to severe increased fragility of long bones and vertebral bodies. Four patients had experienced at least one episode of hyperplastic callus formation. The family history was positive for OI in 3 patients, with an autosomal dominant pattern of inheritance. All type V patients had limitations in the range of pronation/supination in one or both forearms, associated with a radiologically apparent calcification of the interosseous membrane. Three patients had anterior dislocation of the radial head. A radiodense metaphyseal band immediately adjacent to the growth plate was a constant feature in growing patients. Lumbar spine bone mineral density was low and similar to age-matched patients with OI type IV. None of the type V patients presented blue sclerae or dentinogenesis imperfecta, but ligamentous laxity was similar to that in patients with OI type IV. Levels of biochemical markers of bone metabolism generally were within the reference range, but serum alkaline phosphatase and urinary collagen type I N-telopeptide excretion increased markedly during periods of active hyperplastic callus formation. Qualitative histology of iliac biopsy specimens showed that lamellae were arranged in an irregular fashion or had a meshlike appearance. Quantitative histomorphometry revealed decreased amounts of cortical and cancellous bone, like in OI type IV. However, in contrast to OI type IV, parameters that reflect remodeling activation on cancellous bone were mostly normal in OI type V, while parameters reflecting bone formation processes in individual remodeling sites were clearly decreased. Mutation screening of the coding regions and exon/intron boundaries of both collagen type I genes did not reveal any mutations affecting glycine codons or splice sites. In conclusion, OI type V is a new form of autosomal dominant OI, which does not appear to be associated with collagen type I mutations. The genetic defect underlying this disease remains to be elucidated. [source] Pyridinium Cross-Links in Bone of Patients with Osteogenesis Imperfecta: Evidence of a Normal Intrafibrillar Collagen PackingJOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2000Ruud A. Bank Ph.D. Abstract The brittleness of bone in patients with osteogenesis imperfecta (OI) has been attributed to an aberrant collagen network. However, the role of collagen in the loss of tissue integrity has not been well established. To gain an insight into the biochemistry and structure of the collagen network, the cross-links hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) and the level of triple helical hydroxylysine (Hyl) were determined in bone of OI patients (types I, III, and IV) as well as controls. The amount of triple helical Hyl was increased in all patients. LP levels in OI were not significantly different; in contrast, the amount of HP (and as a consequence the HP/LP ratio and the total pyridinoline level) was significantly increased. There was no relationship between the sum of pyridinolines and the amount of triple helical Hyl, indicating that lysyl hydroxylation of the triple helix and the telopeptides are under separate control. Cross-linking is the result of a specific three-dimensional arrangement of collagens within the fibril; only molecules that are correctly aligned are able to form cross-links. Inasmuch as the total amount of pyridinoline cross-links in OI bone is similar to control bone, the packing geometry of intrafibrillar collagen molecules is not disturbed in OI. Consequently, the brittleness of bone is not caused by a disorganized intrafibrillar collagen packing and/or loss of cross-links. This is an unexpected finding, because mutant collagen molecules with a random distribution within the fibril are expected to result in disruptions of the alignment of neighboring collagen molecules. Pepsin digestion of OI bone revealed that collagen located at the surface of the fibril had lower cross-link levels compared with collagen located at the inside of the fibril, indicating that mutant molecules are not distributed randomly within the fibril but are located preferentially at the surface of the fibril. [source] Fetus with osteogenesis imperfecta presenting as increased nuchal translucency thickness in the first trimesterJOURNAL OF CLINICAL ULTRASOUND, Issue 2 2008Charles Tsung-Che Hsieh MD Abstract Type II osteogenesis imperfecta (OI) is a perinatally lethal disorder due to type I collagen abnormalities that has been diagnosed successfully in the second trimester. We report a case of type II OI that was confirmed on postmortem histology and radiography presenting as increased nuchal translucency in the first trimester. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2008 [source] No osteonecrosis in jaws of young patients with osteogenesis imperfecta treated with bisphosphonatesJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 4 2008Barbro Malmgren Background:, Recent reports of osteonecrosis of the jaw (ONJ) after dental surgery in patients treated with second- and third-generation nitrogen-containing bisphosphonates instigated this retrospective study. As treatment with bisphosphonates in patients with osteogenesis imperfecta (OI) has become an important symptomatic therapy, especially for severe forms of the disease, we found it important to investigate whether healing after surgical exposure of jaw bone was influenced by the bisphosponate treatment in our group of children, adolescents and young adults with OI. Subjects and methods:, Disodiumpamidronate was given as monthly intravenous infusion to 64 patients with OI aged 3 months to 20.9 years at the start of treatment (mean 8.1, median 7.7). During 0.5,12.5 years of treatment (mean 4.5, median 4.0), a total individual dose of 140,4020 mg/m2 disodiumpamidronate was given (mean 1623 and median 1460). Ten patients continued with oral alendronate and two with zoledronic acid therapy. In 22 of these patients, 38 dental surgery procedures were performed at the age of 3.4,31.9 years (mean 12.2, median 12.3) after 0.03,7.9 years of treatment (mean 3.6, median 3.4). Results:, Despite long-term intravenous monthly disodiumpamidronate treatment, none of the 64 patients had any clinical signs of ONJ. Conclusions:, The risk of ONJ in these patients must be considered so low that the patients with indications for treatment should be treated and get the chance to experience the well-documented beneficial effect for children with severe OI. [source] Effect of loading on the organization of the collagen fibril network in juvenile equine articular cartilageJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 9 2009Pieter A.J. Brama Abstract We investigated the effects of exercise-induced loading on the collagen network of equine articular cartilage. Collagen fibril architecture at a site (1) subjected to intermittent high-intensity loading was compared with that of an adjacent site (2) sustaining continuous low-level load. From horses exposed to forced exercise (CONDEX group) or not (PASTEX group), the spatial parallelism of fibrils and the orientation angle between fibrils and the surface at depths 9 µm apart through cartilage from surface to tidemark were determined using polarized light microscopy, and expressed as parallelism index (PI) and orientation index (OI). PI was significantly higher in site 2 than 1 in CONDEX and PASTEX groups. PI was significantly higher in forced exercised horses at site 2 but not site 1. OI was significantly greater (more perpendicular to the surface) in the superficial and deep cartilage of site 2 than 1 in both CONDEX and PASTEX groups. Superficial zone OI was higher in exercised horses at site 1 but not at site 2. Exercise increased collagen parallelism and affected orientation. The site differences in OI indicate that Benninghoff's classic predominantly perpendicular arcades appear not to be a consistent architectural feature, but adapt to local forces sustained. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] The effects of RANKL inhibition on fracture healing and bone strength in a mouse model of osteogenesis imperfectaJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2008Demetris Delos Abstract Currently, the standard treatment for osteogenesis imperfecta (OI) is bisphosphonate therapy. Recent studies, however, have shown delayed healing of osteotomies in a subset of OI patients treated with such agents. The current study sought to determine the effects of another therapy, RANKL inhibition, on bone healing and bone strength in the growing oim/oim mouse, a model of moderate to severe OI. Mice [73 oim/oim and 69 wild-type (WT)] were injected twice weekly with either soluble murine RANK (RANK-Fc) (1.5 mg/kg) or saline beginning at 6 weeks of age. At 8 weeks of age, the animals underwent transverse mid-diaphyseal osteotomies of the right femur. Therapy was continued until sacrifice at 2, 3, 4, or 6 weeks postfracture. At 6 weeks post-fracture, greater callus area (6.59,±,3.78 mm2 vs. 2.67,±,2.05 mm2, p,=,0.003) and increased radiographic intensity (mineral density) (0.48,±,0.14 vs. 0.30,±,0.80, p,=,0.005) were found in the RANK-Fc versus saline oim/oim group, indicating a delay in callus remodeling. Despite this delay, mechanical tests at 6 weeks postfracture revealed no significant differences in whole bone properties of stiffness and failure moment. Further, RANKL inhibition resulted in a greater failure moment and greater work to failure for the nonfractured contralateral WT bones compared to the nonfractured saline WT bones. Together, these results demonstrate that RANKL inhibition does not adversely affect the mechanical properties of healing bone in the oim/oim mice, and is associated with increased strength in intact bone in the WT mice. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:153,164, 2008 [source] Electrochemistry and XPS study of an imidazoline as corrosion inhibitor of mild steel in an acidic environmentMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 1 2009O. Olivares-Xometl Abstract The effect of 2-(2-heptadec-8-enyl-4,5-dihydro-imidazol-1-yl)-ethylamine on the corrosion behavior of mild steel in aqueous hydrochloric acid was investigated using weight loss measurements, polarization scans, electrochemical impedance, and X-ray photoelectron spectroscopy (XPS). The inhibition efficiencies and coverage degrees increased with the concentration of inhibitor but decreased proportionally with temperature. It appears that the steric hindrance of the aliphatic chain on the imidazoline ring adsorption may affect inhibitor efficiency. Polarization curves showed that the oleic imidazoline (OI) acted essentially as a mixed type inhibitor, in which the blocking of active sites occurred. As a result of film formation, impedance spectra revealed a considerable increase in the charge transfer resistance as indicated by the second capacitive loop. XPS depth profile analysis observed the presence of nitrogen and carbon species on the inhibitor film, which were associated to the OI. [source] Three-dimensional spatial interpolation of surface meteorological observations from high-resolution local networksMETEOROLOGICAL APPLICATIONS, Issue 3 2008Francesco Uboldi Abstract An objective analysis technique is applied to a local, high-resolution meteorological observation network in the presence of complex topography. The choice of optimal interpolation (OI) makes it possible to implement a standard spatial interpolation algorithm efficiently. At the same time OI constitutes a basis to develop, in perspective, a full multivariate data assimilation scheme. In the absence of a background model field, a simple and effective de-trending procedure is implemented. Three-dimensional correlation functions are used to account for the orographic distribution of observing stations. Minimum-scale correlation parameters are estimated by means of the integral data influence (IDI) field. Hourly analysis fields of temperature and relative humidity are routinely produced at the Regional Weather Service of Lombardia. The analysis maps show significant informational content even in the presence of strong gradients and infrequent meteorological situations. Quantitative evaluation of the analysis fields is performed by systematically computing their cross validation (CV) scores and by estimating the analysis bias. Further developments concern the implementation of an automatic quality control procedure and the improvement of error covariance estimation. Copyright © 2008 Royal Meteorological Society [source] Use of intrapulmonary percussive ventilation (IPV) in the management of pulmonary complications of an infant with osteogenesis imperfectaPEDIATRIC PULMONOLOGY, Issue 11 2009Gustavo Nino MD Abstract Osteogenesis imperfecta (OI) is a genetic disorder characterized by abnormal collagen formation and short stature. These patients present with frequent vertebral, rib, and long bone fractures. There are many respiratory complications associated with OI including pneumonia, the most common cause of mortality in the severe forms of the disease. We present a case of an infant with OI (type III/IV) and significant tracheobronchomalacia who had required multiple hospitalizations for recurrent atelectasis and respiratory failure in the setting of acute respiratory infections. External chest percussion and vibration were avoided because of the risk of rib fractures. intrapulmonary percussive ventilation (IPV) was initiated during an acute illness with good effect, and continued successfully after discharge from hospital. We conclude that IPV represents a safe and effective alternative to airway clearance in infants with OI. Pediatr Pulmonol. 2009; 44:1151,1154. ©2009 Wiley-Liss, Inc. [source] Physiologic neurocirculatory patterns in the head-up tilt test in children with orthostatic intolerancePEDIATRICS INTERNATIONAL, Issue 2 2008Zhang Qingyou Abstract Background: Orthostatic intolerance (OI) is a common clinical manifestation in clinical pediatrics. The head-up tilt (HUT) table test is considered the standard of orthostatic assessment, but the physiologic neurocirculatory profile during HUT has not been fully realized in children with OI. The present study, therefore, was designed to investigate the physiologic patterns that occur during HUT in children with OI. Methods: Ninety children (56 girls; mean age, 11.6 ± 2.3 years) with OI underwent HUT under quiet circumstances. Blood pressure and heart rate were monitored simultaneously. Results: Forty-nine children with OI (54.4%) had vasovagal response with HUT testing; 33 (36.7%), vasodepressor response; six (6.7%), cardioinhibitory response; and 10 (11.1%), mixed response. Twenty-eight children (31.1%) had postural orthostatic tachycardia; one (1.1%), orthostatic hypotension (OH); and 12 (13.3%), normal physiologic response. Patterns of cerebral syncope response and chronotropic incompetence were not observed. Conclusions: Classical vasovagal response was the major physiologic pattern seen in children with OI during HUT testing, and postural orthostatic tachycardia response ranked second. [source] Instructing pelvic floor contraction facilitates transversus abdominis thickness increase during low-abdominal hollowingPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 2 2002Duncan Critchley Abstract Background and Purpose Low abdominal hollowing in four-point kneeling is used clinically to test and rehabilitate transversus abdominis (TrA) but many people find this exercise difficult to perform. Contracting pelvic floor muscles (PF) during low abdominal hollowing may facilitate contraction of TrA. Thickness increase in the abdominal muscles during low abdominal hollowing has been measured with real-time ultrasound scanning and may indicate muscle contraction. The present study investigated the effect of instructing PF contraction on TrA thickness increase during low abdominal hollowing. Method Twelve females and eight males with no reported pelvic floor dysfunction or low back pain in the last two years were taught low abdominal hollowing in four-point kneeling. Subjects performed low abdominal hollowing with and without instruction to contract PF in random order. Transversus abdominis, obliquus internus (OI) and obliquus externus (OE) thickness were measured with ultrasound scanning at rest and during both tests. Results Mean increase in TrA thickness during low abdominal hollowing was 49.71% (SD 26.76%), during low abdominal hollowing with PF it was 65.81% (SD 23.53%). Paired Student's t -tests indicated a significant difference between tests (p=0.015). There were no significant differences between tests for OE or OI thickness increase. Conclusions Instructing healthy subjects to co-contract PF results in greater increase in TrA thickness during low abdominal hollowing in four-point kneeling. This may indicate greater contraction of TrA and thus be useful for clinicians training TrA. Further research could investigate the validity of change of thickness as a measure of abdominal muscle contraction, investigate the effect of instructing PF co-contraction on TrA in patients with low back pain and measure PF and TrA activity simultaneously. Copyright © 2002 Whurr Publishers Ltd. [source] Catalysis of intumescent flame retardancy of polypropylene by metallic compounds,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1 2003Menachem Lewin Abstract Divalent and multivalent metallic compounds catalyze the flame retardancy performance of intumescent systems based on ammonium polyphosphate (APP) and pentaerythritol (petol) in poly(propylene) (PP). The catalytic effect is shown by increases in the oxygen index (OI) and UL-94 ratings. The effect is exerted by small concentrations of the metallic compounds in the range of 0.1,2.5 wt% of the compositions. The effect increases with the concentration of the catalyst until a maximum is reached. At higher concentrations of the catalyst a decrease in the flame retardancy parameters is observed, accompanied in several cases by a degradation and discoloration of the composition. The catalyst replaces melamine in intumescent systems. Catalytic effectiveness is defined and calculated for a number of compounds. Thermogravimetric parameters, such as initial decomposition temperature, temperature of the transition point and residue-after-transitions (RAT) change in parallel with the catalytic effect of the metal compound concentration. Metal compounds investigated include oxides, acetates, acetyl acetonates, borates and sulfates of Mn, Zn, Mg, Al, Ca, Ba,,V, Co, Ni, Cu, Mo, Zr, and Cr. Mechanistic considerations on the activity of the catalysts are presented. Copyright © 2003 John Wiley & Sons, Ltd. [source] First trimester screening for Down syndrome and assisted reproduction: no basis for concernPRENATAL DIAGNOSIS, Issue 7 2001K. R. Wøjdemann Abstract In pregnancies obtained after assisted reproduction the false-positive rate of second trimester Down syndrome (DS) screening is increased by 1.5,3-fold. This may cause an increase in the number of amniocenteses and the fetal loss rate. The present study for the first time examined whether assisted reproductive technologies affect the results of first trimester screening. The markers PAPP-A, free ,-hCG and the nuchal translucency (NT) thickness were examined at 12,14 weeks' gestation. Screening markers in 47 in vitro fertilisation (IVF), 63 ovulation induction (OI) and 3026 spontaneously conceived singleton pregnancies were compared. The MoM (multiples of the median) value in the IVF pregnancies was 1.02 (95% CI: 0.85,1.22) for PAPP-A, 1.14 (95% CI: 0.95,1.37) for ,-hCG and 0.97 (95% CI: 0.89,1.05) for NT; the MoM value in the OI pregnancies was 0.89 (95% CI: 0.76,1.05) for PAPP-A, 1.08 (95% CI: 0.93,1.25) for ,-hCG and 1.02 (95% CI: 0.95,1.11) for NT. The first trimester marker values in assisted reproductive pregnancies and spontaneously conceived pregnancies were not significantly different. Estimated false-positive rates for a risk cut-off of 1:400 varied from 4.7% in IVF pregnancies to 5.1% in OI pregnancies. Therefore the false-positive rate in Down syndrome screening should be independent of the method of conception. Copyright © 2001 John Wiley & Sons, Ltd. [source] Determinants and archetype users of open innovationR & D MANAGEMENT, Issue 4 2009Marcus Matthias Keupp Extant research on open innovation (OI) offers no systematic insight of how and why firms differ regarding the extent to which they conduct OI activities. Whereas past theoretical contributions have focused on explaining the externalisation of R&D activities as a result of firm-external factors, we focus on explaining this externalisation as a result of firm-internal weaknesses, specifically, impediments to innovation. Using the exploration,exploitation dichotomy as our theoretical framework, we develop hypotheses on how impediments to innovation influence the breadth and depth of OI. We then test these hypotheses by using an exceptionally large and detailed data set to estimate population-averaged panel models. Our results provide support for most of the hypothesised relationships. Further, they allow to identify four ,archetypes' of firms that differ significantly regarding the breadth and depth of OI and the importance of impediments. Finally, we discuss the significance of these findings for both academics and managers. [source] Induced ovulation of yellow catfish (Pelteobagrus fulvidraco) using a combination of a gonadotrop-releasing hormone analogue and domperidoneAQUACULTURE RESEARCH, Issue 8 2010Youji Wang Abstract The effects of an intraperitoneal hormone injection of gonadotropin-releasing hormone agonist (D-Ala6, Pro9 -NEt GnRHa) alone or in combination with a dopamine antagonist, domperidone (DOM), on ovulation induction in yellow catfish Pelteobagrus fulvidraco were tested. The hormone treatments were as follows: 6 mg kg,1 body weight (BW) of carp pituitary extract as a positive control, GnRHa 10, 20, 40 and 80 ,g kg,1 BW and a combination of GnRHa and DOM as follows: 10 ,g+5 mg, 20 ,g+10 mg, 40 ,g+20 mg and 80 ,g+40 mg kg,1 BW. Physiological saline (0.7% NaCl) was used as a negative control. Significant differences in the ovulation ratio, latency period and ovulation index (OI) were observed among treatments (P<0.05). The combination of GnRHa and DOM at doses of 40 ,g+20 mg kg,1 BW had higher values of the ovulation ratio and OI, and a shorter latency period compared with other treatments. The highest OI in GnRHa treatments was only 56.67%, suggesting a dopaminergic tone on gonadotropin secretion in this fish at the pre-ovulatory stage. Therefore, ovulation can be successfully induced in yellow catfish with 40 ,g kg,1 GnRHa+20 mg kg,1 DOM without affecting the egg quality. [source] Use of inhaled nitric oxide in the new born period: results from the European inhaled nitric oxide registryACTA PAEDIATRICA, Issue 6 2010Chris Dewhurst Abstract Aims:, The aim of this study was to present data relating to the use of inhaled nitric oxide (iNO) in newborn infants included in the European Inhaled Nitric Oxide Registry. Methods:, Demographic, clinical and therapeutic data from seven European centres are reported. Univariate analyses were performed to identify factors associated with acute response to iNO and survival without extra corporeal membrane oxygenation (ECMO). Results:, A total of 112 newborn infants received iNO, with 40% being less than 34 weeks gestational age. The commonest indication for iNO was secondary pulmonary hypertension. Acute response to iNO was more common in infants with a higher oxygenation index (median OI 32.7 vs 22.6, p = 0.040), although acute response did not predict survival without ECMO. Infants who survived without ECMO had a lower OI prior to therapy (median OI 24 vs 43, p = 0.009), were commenced on a higher starting dose (median dose 20 ppm vs 10 ppm p = 0.013) and received a lower maintenance dose (median dose 10 vs 17 ppm, p = 0.027) than those who died or received ECMO. Conclusion:, Collating and reporting data about iNO therapy in neonates across a number of European centres using a web-based system is feasible. These data may be used to monitor the clinical use of iNO, identify adverse effects, generate research hypotheses and promote high standards in the clinical use of iNO. [source] Efficacy of three treatment schedules in severe meconium aspiration syndromeACTA PAEDIATRICA, Issue 1 2004MD Salvia-Roigés Aim: To compare three different schedules in severe meconium aspiration syndrome (MAS) treatment: standard, bronchoalveolar lavage (BAL) with diluted surfactant, and diluted surfactant BAL plus a single early dexamethasone dose. Methods: Twenty-four full-term newborns with severe MAS (needing mechanical ventilation and with oxygenation index ± 15) were divided into three groups: group I (historical control group; n= 6) treated with standard therapy; group II (n= 7) treated in the first hours of life with one BAL using diluted surfactant (beractant 5 mg/mL) in a volume of 15 mL/kg in four aliquots; and group III (n = 11) treated with one diluted surfactant BAL and a previous single dose of intravenous dexamethasone (0.5 mg/kg) Results: At 12h, groups II and III showed a significant improvement in oxygenation index (OI) compared with group I (14.7% and 27.0% vs , 19.6% respectively; p= 0.012). Group III also showed a significantly lower OI than group I at 24 h (63.6% vs , 27.9%) and at 48 h (87.1% vs 49.6%). Group III, in comparison to group I, showed a lower FiO2 requirement at 12 h (0.66 vs 1), at 24 h (0.4 vs 0.87) and at 48 h (0.35 vs 0.67), and a decrease in the number of days of inhaled nitric oxide administration, mechanical ventilation, oxygen therapy and hospitalisation period. All patients from groups II and III survived and none developed pneumothorax or respiratory infections. Conclusion: Diluted surfactant BAL in the first hours of life combined with an intravenous single dose of dexamethasone may be an effective treatment for severe MAS. [source] Modeling the Development of Children's Use of Optional Infinitives in Dutch and English Using MOSAICCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 2 2006Daniel Freudenthal Abstract In this study we use a computational model of language learning called model of syntax acquisition in children (MOSAIC) to investigate the extent to which the optional infinitive (OI) phenomenon in Dutch and English can be explained in terms of a resource-limited distributional analysis of Dutch and English child-directed speech. The results show that the same version of MOSAIC is able to simulate changes in the pattern of finiteness marking in 2 children learning Dutch and 2 children learning English as the average length of their utterances increases. These results suggest that it is possible to explain the key features of the OI phenomenon in both Dutch and English in terms of the interaction between an utterance-final bias in learning and the distributional characteristics of child-directed speech in the 2 languages. They also show how computational modeling techniques can be used to investigate the extent to which cross-linguistic similarities in the developmental data can be explained in terms of common processing constraints as opposed to innate knowledge of universal grammar. [source] DOC leaching from a coniferous forest floor: modeling a manipulation experiment,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2005Edward Tipping Abstract The DyDOC model simulates the C dynamics of forest soils, including the production and transport of dissolved organic matter (DOM), on the basis of soil hydrology, metabolic processes, and sorption reactions. The model recognizes three main pools of soil C: litter, substrate (an intermediate transformation product), and humic substances. The model was used to simulate the behavior of C in the O horizon of soil under a Norway spruce stand at Asa, Sweden, that had been subjected to experimental manipulations (addition and removal) of above-ground litter inputs and to removal of the Oi and Oe layers. Initially, the model was calibrated using results for the control plots and was able to reproduce the observed total soil C pool and 14C content, DOC flux and DO14C content, and the pool of litter C, together with the assumed content of C in humic substances (20% of the total soil C), and the assumed distribution of DOC between hydrophilic and hydrophobic fractions. The constant describing DOC exchange between micro- and macropores was estimated from short-term variations in DOC concentration. When the calibrated model was used to predict the effects of litter and soil manipulations, it underestimated the additional DOC export (up to 33%) caused by litter addition, and underestimated the 22% reduction in DOC export caused by litter withdrawal. Therefore, an additional metabolic process, the direct conversion of litter to DOC, was added to the model. The addition of this process permitted reasonably accurate simulation of the results of the manipulation experiments, without affecting the goodness-of-fit in the model calibration. The results suggest that, under normal conditions, DOC exported from the Asa forest floor is a mixture of compounds derived from soil C pools with a range of residence times. Approximately equal amounts come from the litter pool (turnover time 4.6 yr), the substrate pool (26 yr), and the humic-substances pool (36 yr). [source] Testing for Local Spatial Autocorrelation in the Presence of Global AutocorrelationJOURNAL OF REGIONAL SCIENCE, Issue 3 2001J. Keith Ord A fundamental concern of spatial analysts is to find patterns in spatial data that lead to the identification of spatial autocorrelation or association. Further, they seek to identify peculiarities in the data set that signify that something out of the ordinary has occurred in one or more regions. In this paper we provide a statistic that tests for local spatial autocorrelation in the presence of the global autocorrelation that is characteristic of heterogeneous spatial data. After identifying the structure of global autocorrelation, we introduce a new measure that may be used to test for local structure. This new statistic Oi is asymptotically normally distributed and allows for straightforward tests of hypotheses. We provide several numerical examples that illustrate the performance of this statistic and compare it with another measure that does not account for global structure. [source] Dependence of structural and optical properties of Zn1,xCdxO films on the Cd compositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 13 2004D. W. Ma Abstract Zn1,xCdxO alloy semiconductors have great latent applications in short wavelength optoelectronic devices. By the dc reactive magnetron sputtering technique, ternary single-phased Zn1,xCdxO (0 , x , 0.53) alloy crystalline films were prepared on glass and sapphire substrates. For x = 0, 0.20, 0.36, 0.53, the band-gaps of the Zn1,xCdxO alloy films were estimated as 3.28, 3.21, 3.11 and 2.65 eV, respectively. Photoluminescence spectrum shows that the near-band-edge energy of the Zn0.8Cd0.2O film has a red-shift of 0.14 eV from that of pure ZnO reported previously. The green-yellow emission in the photoluminescence spectrum is assumed to mainly related to electron transitions from the single ionized oxygen vacancies (Vo+) to Zn, Cd vacancies (VZn,, VC,d), or oxygen interstice (Oi,). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Aspects Regarding the Conception, Modeling and Implementation of an Articulated Robot in Space with Noises and VibrationsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008Virgil Ispas The authors want to conceive and to model a structure of a 6R serial modular industrial robot with six freedom degrees. Some specific points are followed: the direct geometric modelling of the robot using the matrix of rotation method, the given in 3D modelling of the robot, the presentation of its components having some possible applications in the processes of production in the spaces with noises and vibrations. The direct geometrical modelling will be determinate the relative orientation matrices, which express the position of each system Ti, (i=1-6), according to the system Ti,1, also expressing the vectors of relative position of origin Oi of the systems Ti. They will be expressed the orientation of each system Ti in account to the fixed system To attached to the robot base, the set of independent parameters of orientation then are obtained the final equation of the column vector of the generalized coordinates, which express the position and the orientation of the clamping device. The paper presents the two possible applications of the studied robot implementation in a flexible manufacturing cel for the manipulation operations of parts. The robot will be used on the other side for the execution of weld in a points applied to the car carcases. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||||||||||||||