Home About us Contact
|
Home About us Contact | ||
|
|
||
Intermediate Forms (intermediate + form)
Selected AbstractsDiffusion Magnetic Resonance Imaging in Intermediate Form of Maple Syrup Urine DiseaseJOURNAL OF NEUROIMAGING, Issue 4 2002R. N. Sener ABSTRACT An 8-year-old boy with the intermediate variant of maple syrup urine disease is reported. On b= 1000 s/mm2 (heavily diffusion weighted) images of diffusion magnetic resonance imaging, there was symmetric high signal in the globus pallidus, mesencephalon, dorsal pons, and nucleus dentatus, consistent with restriction of the mobility of water molecules. Apparent diffusion coefficient (ADC) maps revealed low ADC values ranging from 0.42 to 0.56 ?10,3mm2/s in these regions, compared to those of apparently unaffected regions in the brain parenchyma ranging from 0.63 to 0.97 ?10,3 mm 2/s. It is suggested that the areas of increased signal (and low ADC values) are the result of dysmyelination as a reflection of disorganized tissue integrity. [source] Endogenous microflora in turbid virgin olive oils and the physicochemical characteristics of these oilsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2008Anastasios Koidis Abstract Cloudy olive oil, the fresh olive juice, is an intermediate form before full precipitation of freshly produced olive oil. Some consumers prefer it because they consider it as more natural and less processed. The cloudy form can persist for several months. The oil is a sort of dispersion/suspension system which can be also described as a micro-emulsion/suspension. Water micro-droplets were found to have a size ranging from 1 to 5,µm. Cloudiness is due to the low water content and the presence of natural emulsifiers in the oil. The suspension is formed by solid particles (5,60,µm) deriving from the olive fruit. They are present in small amounts (12,460,mg/kg oil). In the newly produced olive oil, containing 0.17,0.49% water, a number of microorganisms of different types (bacteria, yeasts, moulds) were found to survive, but at very low concentrations (<3,log,cfu/mL oil). They originate from the exterior of the fruit (epiphytic microflora) and their presence is considered natural. Their enzyme activities do not seem to affect the quality of the final product. [source] Characterization of a nif-regulated flavoprotein (FprA) from Rhodobacter capsulatusFEBS JOURNAL, Issue 3 20002S] ferredoxin, Redox properties, molecular interaction with a [2Fe A flavoprotein from Rhodobacter capsulatus was purified as a recombinant (His)6 -tag fusion from an Escherichia coli clone over-expressing the fprA structural gene. The FprA protein is a homodimer containing one molecule of FMN per 48-kDa monomer. Reduction of the flavoprotein by dithionite showed biphasic kinetics, starting with a fast step of semiquinone (SQ) formation, and followed by a slow reduction of the SQ. This SQ was in the anionic form as shown by EPR and optical spectroscopies. Spectrophotometric titration gave a midpoint redox potential for the oxidized/SQ couple of Em1 = +20 mV (pH 8.0), whereas the SQ/hydroquinone couple could not be titrated due to the thermodynamic instability of SQ associated with its slow reduction process. The inability to detect the intermediate form, SQ, upon oxidative titration confirmed this instability and led to an estimate of Em2 , Em1 of > 80 mV. The reduction of SQ by dithionite was significantly accelerated when the [2Fe,2S] ferredoxin FdIV was used as redox mediator. The midpoint redox potential of this ferredoxin was determined to be ,275 ± 2 mV at pH 7.5, consistent with FdIV serving as electron donor to FprA in vivo. FdIV and FprA were found to cross-react when incubated together with the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, giving a covalent complex with an Mr of , 60 000. Formation of this complex was unaffected by the redox states of the two proteins. Other [2Fe,2S] ferredoxins, including FdV and FdVI from R. capsulatus, were ineffective as electron carriers to FprA, and cross-reacted poorly with the flavoprotein. The possible function of FprA with regard to nitrogen fixation was investigated using an fprA -deleted mutant. Although nitrogenase activity was significantly reduced in the mutant compared with the wild-type strain, nitrogen fixation was apparently unaffected by the fprA deletion even under iron limitation or microaerobic conditions. [source] Schwann cells and the pathogenesis of inherited motor and sensory neuropathies (Charcot-Marie-Tooth disease)GLIA, Issue 4 2006Philipp Berger Abstract Over the last 15 years, a number of mutations in a variety of genes have been identified that lead to inherited motor and sensory neuropathies (HMSN), also called Charcot-Marie-Tooth disease (CMT). In this review we will focus on the molecular and cellular mechanisms that cause the Schwann cell pathologies observed in dysmyelinating and demyelinating forms of CMT. In most instances, the underlying gene defects alter primarily myelinating Schwann cells followed by secondary axonal degeneration. The first set of proteins affected by disease-causing mutations includes the myelin components PMP22, P0/MPZ, Cx32/GJB1, and periaxin. A second group contains the regulators of myelin gene transcription EGR2/Krox20 and SOX10. A third group is composed of intracellular Schwann cells proteins that are likely to be involved in the synthesis, transport and degradation of myelin components. These include the myotubularin-related lipid phosphatase MTMR2 and its regulatory binding partner MTMR13/SBF2, SIMPLE, and potentially also dynamin 2. Mutations affecting the mitochondrial fission factor GDAP1 may indicate an important contribution of mitochondria in myelination or myelin maintenance, whereas the functions of other identified genes, including NDRG1, KIAA1985, and the tyrosyl-tRNA synthase YARS, are not yet clear. Mutations in GDAP1, YARS, and the pleckstrin homology domain of dynamin 2 lead to an intermediate form of CMT that is characterized by moderately reduced nerve conduction velocity consistent with minor myelin deficits. Whether these phenotypes originate in Schwann cells or in neurons, or whether both cell types are directly affected, remains a challenging question. However, based on the advances in systematic gene identification in CMT and the analyses of the function and dysfunction of the affected proteins, crucially interconnected pathways in Schwann cells in health and disease have started to emerge. These networks include the control of myelin formation and stability, membrane trafficking, intracellular protein sorting and quality control, and may extend to mitochondrial dynamics and basic protein biosynthesis. © 2006 Wiley-Liss, Inc. [source] Thermally-Induced Phase Transitions in the Uniaxially-Oriented , Form of Syndiotactic PolystyreneMACROMOLECULAR SYMPOSIA, Issue 1 2006E. Bhoje Gowd Abstract The empty , (,e) form of uniaxially-oriented syndiotactic polystyrene (sPS) samples were obtained by extracting the solvent molecules from the , form of sPS and solvent complex in acetone and methanol. Temperature dependence of the X-ray fiber diagrams starting from the uniaxially-oriented ,e and , form has been measured successfully at various temperatures for the first time. The transition behavior was traced clearly by separating the equatorial and layer line reflections. The ,e form transformed to the , form via an intermediate form. The intermediate form is speculated to take disordered structure due to the empty cavities present in the ,e form. Calorimetric studies showed an endotherm followed by an exotherm during this phase transition, which is consistant with such a speculation. On the other hand the , form transformed to the , form directly without passing through the intermediate form or ,e form. During the , to , phase transition the solvent molecules evaporate through the columnar structure in a broad range of temperature, allowing the transition to occur smoothly. [source] A new species of Pseudoloris (Omomyidae, Primates) from the middle Eocene of Sant Jaume de Frontanyà (Eastern Pyrenees, Spain)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Raef Minwer-Barakat Abstract In this article we describe a new species of Pseudoloris (Omomyidae, Primates) from the Robiacian (middle Eocene) locality of Sant Jaume de Frontanyà (Eastern Pyrenees, Spain). Pseudoloris pyrenaicus is characterized by its medium size, thickened paracristid, absence of a distinct paraconid, and well-developed buccal cingulid in the lower molars, large hypoconulid in the M3, paraconule and hypocone reduced in the M1 and M2 and absent in the M3. The material from Sant Jaume de Frontanyà constitutes the most abundant sample of the genus Pseudoloris found until now in the Iberian Peninsula. Almost all the dental elements have been recovered, including those teeth hardly known for other species of the genus, such as lower and upper incisors. The new species shows intermediate features between Pseudoloris isabenae from Capella and Pseudoloris parvulus, present in different Spanish and French sites. Therefore, we consider that Pseudoloris pyrenaicus is an intermediate form between these two species. Am J Phys Anthropol 143:92,99, 2010. © 2010 Wiley-Liss, Inc. [source] (Acetato-,O)aqua(1H -imidazole-,N3)(picolinato-,2N,O)copper(II) 0.87-hydrate: a Z,> 1 structureACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009Anne-Christine Chamayou The crystal structure of the title compound, [Cu(C6H4NO2)(C2H3O2)(C3H4N2)(H2O)]·0.87H2O, has a square-pyramidal-coordinated CuII centre (the imidazole is trans to the picolinate N atom, the acetate is trans to the picolinate ,CO2 group and the aqua ligand is in a Jahn,Teller-elongated apical position) and has two symmetry-independent molecules in the unit cell (Z, = 2), which are connected through complementary imidazole,picolinate N,H...O hydrogen bonding. The two partially occupied solvent water molecules are each disordered over two positions. The disordered solvent water molecules, together with pseudosymmetry elements, support the notion that a crystal structure with multiple identical chemical formula units in the structural asymmetric unit (Z, > 1) can represent a crystal `on the way', that is, a kinetic intermediate form which has not yet reached its thermodynamic minimum. Neighbouring molecules form ,,, stacks between their imidazole and picolinate N-heterocycles, with centroid,centroid distances in the range 3.582,(2),3.764,(2),Å. [source] Acoustic Features of Female Chacma Baboon BarksETHOLOGY, Issue 1 2001Julia Fischer We studied variation in the loud barks of free-ranging female chacma baboons (Papio cynocephalus ursinus) with respect to context, predator type, and individuality over an 18-month period in the Moremi Game Reserve, Botswana. To examine acoustic differences in relation to these variables, we extracted a suite of acoustic parameters from digitized calls and applied discriminant function analyses. The barks constitute a graded continuum, ranging from a tonal, harmonically rich call into a call with a more noisy, harsh structure. Tonal barks are typically given when the signaler is at risk of losing contact with the group or when a mother and infant have become separated (contact barks). The harsher variants are given in response to large predators (alarm barks). However, there are also intermediate forms between the two subtypes which may occur in both situations. This finding is not due to an overlap of individuals' distinct distributions but can be replicated within individuals. Within the alarm bark category, there are significant differences between calls given in response to mammalian carnivores and those given in response to crocodiles. Again, there are intermediate variants. Both alarm call types are equally different from contact barks, indicating that the calls vary along different dimensions. Finally, there are consistent, significant differences among different individuals' calls. However, individual identity in one call type cannot directly be inferred from knowledge of the individuals' call characteristics in the other. In sum, the barks of female baboons potentially provide rich information to the recipients of these signals. The extent to which baboons discriminate between alarm and contact barks, and classify calls according to context and/or acoustic similarity will be described in a subsequent paper. [source] Interaction between catalytically inactive calpain and calpastatinFEBS JOURNAL, Issue 8 2006Evidence for its occurrence in stimulated cells Conformational changes in the calpain molecule following interaction with natural ligands can be monitored by the binding of a specific monoclonal antibody directed against the catalytic domain of the protease. None of these conformational states showed catalytic activity and probably represent intermediate forms preceding the active enzyme state. In its native inactive conformation, calpain shows very low affinity for this monoclonal antibody, whereas, on binding to the ligands Ca2+, substrate or calpastatin, the affinity increases up to 10-fold, with calpastatin being the most effective. This methodology was also used to show that calpain undergoes similar conformational changes in intact cells exposed to stimuli that induce either a rise in intracellular [Ca2+] or extensive diffusion of calpastatin into the cytosol without affecting Ca2+ homeostasis. The fact that the changes in the calpain state are also observed under the latter conditions indicates that calpastatin availability in the cytosol is the triggering event for calpain,calpastatin interaction, which is presumably involved in the control of the extent of calpain activation through translocation to specific sites of action. [source] Glomeruloid peritoneal implants in ovarian serous borderline tumours , distinction between invasive and non-invasive implants and pathogenesisHISTOPATHOLOGY, Issue 5 2009Eung-Seok Lee Aims:, To determine whether or not the glomeruloid implants (GI) composed of papillary cores within clear spaces lined by mesothelial cells or tumour cells located in superficial or deep peritoneal tissue in ovarian serous borderline tumours (SBTs) are invasive. Methods and results:, We examined the differences in incidence, histological and immunohistochemical findings among three groups: 100 GI with mesothelial cells lining clear space (type I), 100 GI with tumour cells lining clear space (type II), and 100 invasive implants with clefts but no lining cells from 30 cases of SBT with peritoneal implants. The type I lesion had characteristics of non-invasive implants with a tendency for smooth contours (100/100), superficial location (71/100), absence of desmoplasia (100/100) and absence of surrounding destructive invasion (100/100), In contrast, type II GI had irregular contours (67/100), deep location (93/100), presence of desmoplastic reaction (100/100) and presence of destructive invasion (12/100). Immunohistological studies suggested intermediate forms between the two types of lesions. Conclusions:, Type I GI are non-invasive implants, whereas type II GI are invasive implants and it is important to evaluate the presence and nature of cells lining the clear space in determining whether implants associated with ovarian SBTs are invasive or not. [source] Molecular and serological aspects of HBsAg-negative hepatitis B virus infections in North AmericaJOURNAL OF MEDICAL VIROLOGY, Issue 1 2003C.C. Hsia Abstract A few hepatitis B virus (HBV) infections are characterized by the presence of HBV DNA in serum or liver tissue, or both, in the absence of detectable hepatitis B surface antigen (HBsAg) in serum. However, such infections have rarely been described previously in North American patients. In the present study, 31 hepatocellular carcinoma (HCC) patients from the United States and Canada who had no detectable HBsAg in their serum were studied. In these 31 HBsAg-negative HCC patients, HBV DNA was detected in HCC and/or in adjacent nontumorous liver tissue using nested polymerase chain reaction (PCR) in 5/9 (56%) patients from the United States and in 12/22 (55%) from Canada. The 17 HBV DNA-positive/HBsAg-negative patients from the United States and Canada included 9 without any serological markers for HBV and 8 with detectable antibodies to hepatitis B core antigen. In these patients, HBV genotype C was the most prevalent genotype (11/17; 64%). HBV genotypes have not been previously reported in HCC patients from North America. Replicative intermediate forms of HBV (covalently closed circular HBV DNA) were detected in 2/17 (12%) HBV DNA-positive/HBsAg-negative patients, indicating that at least two of these patients had actively replicating HBV infections. The use of tests to detect HBV DNA permitted the identification of HBV infections in HBsAg-negative HCC patients from North America. Among these patients, those with antibody to hepatitis C virus (HCV) would otherwise have been designated "HCV-associated HCCs" based on serological tests alone. These findings provide a new perspective on determining the possible viral etiologies of HCCs in North America. J. Med. Virol. 70: 20,26, 2003. © 2003 Wiley-Liss, Inc. [source] Phase Transformations in the High-Temperature Form of Pure and TiO2 -Stabilized Ta2O5JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007Geoff L. Brennecka The high-temperature forms of undoped tantalum pentoxide (H-100Ta2O5) and TiO2,modified Ta2O5 (H-92Ta2O5,8TiO2) were investigated by in situ synchrotron X-ray diffraction and Raman scattering measurements. Two unquenchable and reversible phase transformations were observed in pure H-Ta2O5, while only one was detected for TiO2 -stabilized H-Ta2O5. Diffraction studies were consistent with displasive transformations, but hot-stage Raman spectroscopy indicated the existence of transient intermediate forms during the transformations. Use of complementary techniques enabled the reinterpretation of phase transformations in light of a newly proposed crystal structure model for H-Ta2O5,1 and emphasized the structural contributions of the oxygen sublattice. [source] Protein misfolding in neurodegenerative diseasesNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 3 2004E. I. Agorogiannis A common pathogenic mechanism shared by diverse neurodegenerative disorders, like Alzheimer's disease, Parkinson's disease, Huntington's disease and transmissible spongiform encephalopathies, may be altered protein homeostasis leading to protein misfolding and aggregation of a wide variety of different proteins in the form of insoluble fibrils. Mutations in the genes encoding protein constituents of these aggregates have been linked to the corresponding diseases, thus a reasonable scenario of pathogenesis was based on misfolding of a neurone-specific protein that forms insoluble fibrils that subsequently kill neuronal cells. However, during the past 5 years accumulating evidence has revealed the neurotoxic role of prefibrillar intermediate forms (soluble oligomers and protofibrils) produced during fibril formation. Many think these may be the predominant neurotoxic species, whereas microscopically visible fibrillar aggregates may not be toxic. Large protein aggregates may rather be simply inactive, or even represent a protective state that sequesters and inactivates toxic oligomers and protofibrils. Further understanding of the biochemical mechanisms involved in protein misfolding and fibrillization may optimize the planning of common therapeutic approaches for neurodegenerative diseases, directed towards reversal of protein misfolding, blockade of protein oligomerization and interference with the action of toxic proteins. [source] Cytology, palynology, and taxonomy of Asteropyrum and four other genera of RanunculaceaeBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2006QIONG YUAN A karyomorphological study of two species in Asteropyrum (Ranunculaceae) and five in presumably related genera (one each in Caltha, Coptis, and Dichocarpum and two in Thalictrum) reveals close similarities between Asteropyrum and Caltha, but obvious differences between Asteropyrum and Coptis, Dichocarpum, and Thalictrum, in some karyological features, such as the structure of the interphase nuclei, chromosome size, basic chromosome number, and condensation behaviour of chromosomes during the mitotic prophase. The chromosomes of Asteropyrum are categorized as being of the R-type and the basic chromosome number is confirmed as x = 8, indicating a possible close affinity of Asteropyrum to members in the subfamily Helleboroideae, in particular to Caltha and its allies. Asteropyrum peltatum and Asteropyrum cavaleriei are shown to be more or less differentiated from each other in gross morphology and palynology, and somewhat independent in geographical distribution, albeit with intermediate forms occurring where their distribution zones overlap. It seems justifiable to treat them as two subspecies of A. peltatum. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 152, 15,26. [source] | |||||||||||||||||||