858 resultados para product variant
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Overcommitment of development capacity or development resource deficiencies are important problems in new product development (NPD). Existing approaches to development resource planning have largely neglected the issue of resource magnitude required for NPD. This research aims to fill the void by developing a simple higher-level aggregate model based on an intuitive idea: The number of new product families that a firm can effectively undertake is bound by the complexity of its products or systems and the total amount of resources allocated to NPD. This study examines three manufacturing companies to verify the proposed model. The empirical results confirm the study`s initial hypothesis: The more complex the product family, the smaller the number of product families that are launched per unit of revenue. Several suggestions and implications for managing NPD resources are discussed, such as how this study`s model can establish an upper limit for the capacity to develop and launch new product families.
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We extended the standard neoclassical model of investment for the case of an open economy. Our model shows that risk premium not only creates a wedge between the marginal product of capital across countries but also reduces an economy`s savings rate. A riskier market thus presents a lower income per capita, ceteris paribus. Our empirical analysis, from 1950 to 2003, lends support to the conclusion that both risk and the correction for output price to investment ratio help to explain the differentials.
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Context: 21-hydroxylase deficiency (21OHD) is a common genetic disorder caused by mutations in the CYP21A2 gene, which encodes the adrenal 21-hydroxylase, microsomal P450c21. CYP21A2 gene mutations generally correlate well with impaired P450c21 enzymatic activity and the clinical findings in 21OHD, but occasional discrepancies between genotype and phenotype suggest the effects of modifier genes. Mutations in P450 oxidoreductase (POR), the protein that transfers electrons from reduced nicotinamide adenine dinucleotide phosphate to all microsomal P450s, can ameliorate the 21OHD phenotype and, therefore, could be a modifier gene. Objectives: We sought to identify POR variants in patients with 21OHD having discordant phenotype and genotype, and to evaluate their effect on 21-hydroxylase activity. Patients and Methods: We determined the CYP21A2 genotypes of 313 Brazilian patients with 21OHD and correlated the genotype and phenotype. The POR gene was sequenced in 17 patients with discordant genotype and phenotype. Wild-type and A503V POR, and P450c21 were expressed in bacteria and reconstituted in vitro. Activities were assayed by conversion of [C-14] progesterone to deoxycorticosterone and [H-3]17-hydroxyprogesterone to 11-deoxycortisol, and assessed by thin layer chromatography and phosphorimaging. Results: The A503V POR variant was found in 10 of 30 alleles, the same ratio as in the normal population. There were no significant differences in Michaelis constant, maximum velocity and maximum velocity/Michaelis constant of 21-hydroxylase activity supported by wild-type and A503V POR. Conclusion: The only POR missense polymorphism found in atypical 21OHD patients was A503V. Although A503V reduces P450c17 enzymatic activity, it does not influence P450c21 activity, indicating that POR A503V does not modify the 21OHD phenotype.
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Small mammals are subject to predation from mammalian, avian and reptilian predators. There is an obvious advantage for prey species to detect the presence of predators in their environment, enabling them to make decisions about movement and foraging behaviour based on perceived risk of predation. We examined the effect of faecal odours from marsupial and eutherian predators, and a native reptilian predator, on the behaviour of three endemic Australian rodent species (the fawn-footed melomys, Melomys cervinipes, the bush rat, Rattus fuscipes, and the giant white-tailed rat, Uromys caudimaculatus) in rainforest remnants on the Atherton Tableland, North Queensland, Australia. Infrared camera traps were used to assess visit rates of rodents to odour stations containing faecal and control odours. Rodents avoided odour stations containing predator faeces, but did not avoid herbivore or control odours. The responses of the three prey species differed: in the late wet season U. caudimaculatus avoided predator odours, whereas R. fuscipes and M. cervinipes did not. In contrast, in the late dry season all three species avoided odour stations containing predator odours. We speculate that these different responses may result from variation in life history traits between the species. (c) 2006 The Association for the Study of Animal Behaviour Published by Elsevier Ltd. All rights reserved.
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Background. Chagas disease is caused by the protozoan parasite Trypanosoma cruzi. Among T. cruzi-infected individuals, only a subgroup develops severe chronic Chagas cardiomyopathy (CCC); the majority remain asymptomatic. T. cruzi displays numerous ligands for the Toll-like receptors (TLRs), which are an important component of innate immunity that lead to the transcription of proinflammatory cytokines by nuclear factor-kappa B. Because proinflammatory cytokines play an important role in CCC, we hypothesized that single-nucleotide polymorphisms (SNPs) in the genes that encode proteins in the TLR pathway could explain differential susceptibility to CCC among T. cruzi-infected individuals. Methods. For 169 patients with CCC and 76 T. cruzi-infected, asymptomatic individuals, we analyzed SNPs by use of polymerase chain reaction-restriction fragment length polymorphism analysis for the genes TLR1, TLR2, TLR4, TLR5, TLR9, and MAL/TIRAP, which encodes an adaptor protein. Results. Heterozygous carriers of the MAL/TIRAP variant S180L were more prevalent in the asymptomatic group (24 [32%] of 76 subjects) than in the CCC group (21 [12%] of 169) (chi(2) = 12.6; P = .0004 [adjusted P (P(c)) = .0084]; odds ratio [OR], 0.31 [95% confidence interval {CI}, 0.16-0.60]). Subgroup analysis showed a stronger association when asymptomatic patients were compared with patients who had severe CCC (i.e., patients with left-ventricular ejection fraction <= 40%) (chi(2) = 11.3; P = .0008 [P(c) = .017]; OR, 0.22 [95% CI, 0.09-0.56]) than when asymptomatic patients were compared with patients who had mild CCC (i.e., patients with left-ventricular ejection fraction >40%) (chi(2) = 7.7; P = .005 [P(c) = .11]; OR, 0.33 [95% CI, 0.15-0.73]). Conclusion. T. cruzi-infected individuals who are heterozygous for the MAL/TIRAP S180L variant that leads to a decrease in signal transduction upon ligation of TLR2 or TLR4 to their respective ligand may have a lower risk of developing CCC.
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Condensation of (-)-norephedrine with excess formaldehyde under mild conditions leads to formation of the 2:1 condensation product N,N'-methylenebis(4-methyl-5-phenyl)oxazolidine compared with the reaction with 1 mol of formaldehyde, which leads to 4-methyl-5-phenyloxazolidine. H-1 and C-13 NMR spectroscopy was used to monitor the stability of this compound and its decomposition products. The 2:1 condensation product is found to be stable in CDC1(3) but breaks down rapidly in CD3OD to yield a 50:50 mixture of 4-methyl-5-phenyloxazolidine and 3-hydroxymethyl-4-methyl-5-phenyloxazolidine. Upon addition of D2O to this equimolar mixture, the latter compound decomposes to norephedrine and formaldehyde, whereas the former compound is stable. (C) 1997 by John Wiley & Sons, Ltd.
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Mantle cell lymphoma (MCL) commonly involves extranodal sites, usually as a manifestation of disseminated disease. In rare cases, MCLs may arise as a primary tumor in the skin. Blastoid mantle cell lymphoma (BV-MCL) is a rare variant and has a more aggressive clinical course. The phenotype of BV-MCL is characterized as CD20(+), CD5(+), cyclin D1(+), CD23(-), and CD10(-). Interphase fluorescence in situ hybridization shows a characteristic t(11; 14) fusion pattern. We report a case of a BV-MCL arising in skin as primary cutaneous MCL with the characteristic immunophenotype and translocation.
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We report a case of an inflammatory variant of epidermolysis bullosa acquisita in a 53-year-old male, with itching blistering eruption on the trunk, armpits and limbs for six months. The skin biopsy specimen showed subepidermal blister with neutrophils. Direct immunofluorescence revealed linear depositions of IgG, IgA, IgM and C3 at the basement membrane; indirect immunofluorescence and salt split skin were negative. Antinuclear antibodies were also negative. Improvement of the blisters followed treatment with systemic corticotherapy and some lesions healed with milia. This is a rare presentation of epidermolysis bullosa acquisita, with inflammatory lesions at first.
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Ullrich congenital muscular dystrophy (UCMD) is a disabling and life-threatening disorder resulting from either recessive or dominant mutations in genes encoding collagen VI. Although the majority of the recessive UCMD cases have frameshift or nonsense mutations in COL6A1, COL6A2, or COL6A3, recessive structural mutations in the COL6A2 C-globular region are emerging also. However, the underlying molecular mechanisms have remained elusive. Here we identified a homozygous COL6A2 E624K mutation (C1 subdomain) and a homozygous COL6A2 R876S mutation (C2 subdomain) in two UCMD patients. The consequences of the mutations were investigated using fibroblasts from patients and cells stably transfected with the mutant constructs. In contrast to expectations based on the clinical severity of these two patients, secretion and assembly of collagen VI were moderately affected by the E624K mutation but severely impaired by the R876S substitution. The E624K substitution altered the electrostatic potential of the region surrounding the metal ion-dependent adhesion site, resulting in a collagen VI network containing thick fibrils and spots with densely packed microfibrils. The R876S mutation prevented the chain from assembling into triple-helical collagen VI molecules. The minute amount of collagen VI secreted by the R876S fibroblasts was solely composed of a faster migrating chain corresponding to the C2a splice variant with an alternative C2 subdomain. In transfected cells, the C2a splice variant was able to assemble into short microfibrils. Together, the results suggest that the C2a splice variant may functionally compensate for the loss of the normal COL6A2 chain when mutations occur in the C2 subdomain.
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Methods We performed a detailed analysis of one 15q single nucleotide polymorphism (SNP) (rs16969968) with smoking behaviour and cancer risk in a total of 17 300 subjects from five LC studies and four upper aerodigestive tract (UADT) cancer studies. Results Subjects with one minor allele smoked on average 0.3 cigarettes per day (CPD) more, whereas subjects with the homozygous minor AA genotype smoked on average 1.2 CPD more than subjects with a GG genotype (P < 0.001). The variant was associated with heavy smoking (> 20 CPD) [odds ratio (OR) = 1.13, 95% confidence interval (CI) 0.96-1.34, P = 0.13 for heterozygotes and 1.81, 95% CI 1.39-2.35 for homozygotes, P < 0.0001]. The strong association between the variant and LC risk (OR = 1.30, 95% CI 1.23-1.38, P = 1 x 10(-18)), was virtually unchanged after adjusting for this smoking association (smoking adjusted OR = 1.27, 95% CI 1.19-1.35, P = 5 x 10(-13)). Furthermore, we found an association between the variant allele and an earlier age of LC onset (P = 0.02). The association was also noted in UADT cancers (OR = 1.08, 95% CI 1.01-1.15, P = 0.02). Genome wide association (GWA) analysis of over 300 000 SNPs on 11 219 subjects did not identify any additional variants related to smoking behaviour. Conclusions This study confirms the strong association between 15q gene variants and LC and shows an independent association with smoking quantity, as well as an association with UADT cancers.
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Background: Sequence variants located at 15q25 have been associated with lung cancer and propensity to smoke. We recently reported an association between rs16969968 and risk of upper aerodigestive tract (UADT) cancers (oral cavity, oropharynx, hypopharynx, larynx, and esophagus) in women (OR = 1.24, P = 0.003) with little effect in men (OR = 1.04, P = 0.35). Methods: In a coordinated genotyping study within the International Head and Neck Cancer Epidemiology (INHANCE) consortium, we have sought to replicate these findings in an additional 4,604 cases and 6,239 controls from 10 independent UADT cancer case-control studies. Results: rs16969968 was again associated with UADT cancers in women (OR = 1.21, 95% CI = 1.08-1.36, P = 0.001) and a similar lack of observed effect in men [OR = 1.02, 95% CI = 0.95-1.09, P = 0.66; P-heterogeneity (P(het)) = 0.01]. In a pooled analysis of the original and current studies, totaling 8,572 UADT cancer cases and 11,558 controls, the association was observed among females (OR = 1.22, 95% CI = 1.12-1.34, P = 7 x 10(-6)) but not males (OR = 1.02, 95% CI = 0.97-1.08, P = 0.35; P(het) = 6 x 10(-4)). There was little evidence for a sex difference in the association between this variant and cigarettes smoked per day, with male and female rs16969968 variant carriers smoking approximately the same amount more in the 11,991 ever smokers in the pooled analysis of the 14 studies (P(het) = 0.86). Conclusions: This study has confirmed a sex difference in the association between the 15q25 variant rs16969968 and UADT cancers. Impact: Further research is warranted to elucidate the mechanisms underlying these observations. Cancer Epidemiol Biomarkers Prev; 20(4); 658-64. (C) 2011 AACR.
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We have examined MC1R variant allele frequencies in the general population of South East Queensland and in a collection of adolescent dizygotic and monozygotic twins and family members to define statistical associations with hair and skin color, freckling, and mole count. Results of these studies are consistent with a linear recessive allelic model with multiplicative penetrance in the inheritance of red hair. Four alleles, D84E, R151C, R160W, and D294H, are strongly associated with red hair and fair skin with multinomial regression analysis showing odds ratios of 63, 118, 50, and 94, respectively. An additional three low-penetrance alleles V60L, V92M, and R163Q have odds ratios 6, 5, and 2 relative to the wild-type allele. To address the cellular effects of MC1R variant alleles in signal transduction, we expressed these receptors in permanently transfected HEK293 cells. Measurement of receptor activity via induction of a cAMP-responsive luciferase reporter gene found that the R151C and R160W receptors were active in the presence of NDP-MSH ligand, but at much reduced levels compared with that seen with the wild-type receptor. The ability to stimulate phosphorylation of the cAMP response element binding protein (CREB) transcription factor was also apparent in all stimulated MC1R variant allele-expressing HEK293 cell extracts as assessed by immunoblotting. In contrast, human melanoma cell lines showed wide variation in the their ability to undergo cAMP-mediated CREB phosphorylation. Culture of human melanocytes of known MC1R genotype may provide the best experimental approach to examine the functional consequences for each MC1R variant allele. With this objective, we have established more than 300 melanocyte cell strains of defined MC1R genotype.
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Epidermal growth factor receptor (EGFR) gene overexpression has been implicated in the development of many types of tumors, including glioblastomas, the most frequent diffusely infiltrating astrocytomas. However, little is known about the influence of the polymorphisms of EGFR on EGFR production and/or activity, possibly modulating the susceptibility to astrocytomas. This study aimed to examine the association of two EGFR promoter polymorphisms (c.-191C > A and c.-216G > T) and the c.2073A > T polymorphism located in exon 16 with susceptibility to astrocytomas, EGFR gene expression and survival in a case-control study of 193 astrocytoma patients and 200 cancer-free controls. We found that the variant TT genotype of the EGFR c.2073A > T polymorphism was associated with a significantly decreased risk of astrocytoma when compared with the AA genotype [sex- and age-adjusted odds ratio 0.51, 95% confidence interval 0.26-0.98]. No association of the two promoter EGFR polymorphisms (or combinations of these polymorphisms) and risk of astrocytomas, EGFR expression or survival was found. Our findings suggest that modulation of the EGFR c.2073A > T polymorphism could play a role in future therapeutic approaches to astrocytoma. (Int J Biol Markers 2008; 23: 140-6)