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At least 829 records · Page 46Linked to original sources
PubMed1997

Use of a resonant mirror biosensor to characterize the interaction of carboxypeptidase A with an elicited monoclonal antibody.

The binding of apocarboxypeptidase A to an immobilized form of its elicited monoclonal antibody has been used to explore the potential of a biosensor instrument (IAsys) based on resonant mirror technology for the quantitative characterization of antibody-antigen interactions. Advantage has been taken of the stirred cuvette design of the IAsys instrument to develop a stepwise titration procedure for thermodynamic characterization of the interaction, an association equilibrium constant of 3.3 (+/-0.9) x 10(7) M-1 having been obtained under the conditions studied (0.1 M Tris/HCl-0.5 M NaCl, pH 7.5, 21 degrees C). In a test of the feasibility of subjecting the time course of biosensor response to conventional pseudo-first-order kinetic analysis, nonconformity of results with such description was encountered at high and low concentrations of apocarboxypeptidase A. Whereas the deviations from Langmuirian kinetic behavior at high antigen concentrations undoubtedly stem from the same sources as those already encountered in studies with the BIA-core biosensor instrument, the deviations at the other concentration extreme occur in a range in which the assumed constancy of free antigen concentration in the liquid phase is becoming a poor approximation. An alternative approach in such circumstances has been tested in which prior thermodynamic characterization is a prerequisite for rate constant evaluation by means of a second-order kinetic analysis. Finally, the effect of soluble anticarboxypeptidase A on the pseudo-first-order kinetics of the biosensor response has been used to illustrate a simple kinetic procedure for evaluating the affinity constant for the antibody-antigen interaction in solution, a value of 1.9 (+/-0.2) x 10(8) M-1 being obtained by such means.

Antibodies, Monoclonal↗
PubMed1998

Characterization of Helicobacter pylori interactions with sialylglycoconjugates using a resonant mirror biosensor.

A new optical biosensor technique based on the resonant mirror was used to characterize Helicobacter pylori strains according to their sialic acid binding, demonstrating the suitability of using intact bacteria in real-time measurements and classifying strains based on their binding abilities. Results obtained from both competition and displacement assays using different glycoconjugates confirmed that several, but not all, H.pylori strains express sialic acid-binding adhesin(s), specific for alpha-2,3-sialyllactose. The adhesin, removable from the bacterial surface by water extraction, is not related to other reported H.pylori cell surface proteins with binding ability to sialylated compounds such as sialylglycoceramides.

Biosensing Techniques↗
PubMed1995

An intramolecular triplex structure from non-mirror repeated sequence containing both Py:Pu.Py and Pu:Pu.Py triads.

A plasmid insert containing the (TA)7GATC(TA)7 inverted repeat and an adjacent (AG)7 tract adopts a cruciform structure at neutral pH. However, under acidic conditions the cruciform becomes readily disrupted in favor of a triplex. The (AG)7.(CT)7 duplex and one strand of the (TA)7GATC(TA)7 element are engaged in the three-stranded DNA formation, as determined using single-stranded DNA specific probes. The structure extrudes by displacing the (TA)7 strand adjacent to the (AG)7, and folding it back into the major groove of the (AG)7.(CT)7 duplex. This new variant of H-DNA is supercoil and pH dependent, requiring pH 6.1 or lower to form. The triplex is stabilized by T:A.T and A+:G.C triads. This unusual triad composition (50% of T:A.T and 50% of A+:G>C), that has not previously been observed in intramolecular triplexes, violates both the widely accepted division of triplexes into Py:Pu.Py or Pu:Pu.Py types and the requirement for mirror repeat symmetry.

Base Sequence↗
PubMed1997

Alkaline phosphatase-Strep tag fusion protein binding to streptavidin: resonant mirror studies.

The properties of a fusion protein comprising a streptavidin recognition sequence (Strep tag) fused to the C terminus of Escherichia coli alkaline phosphatase are described. The catalytic properties were determined with p-nitrophenyl phosphate and compared to those of the native E. coli alkaline phosphatase. It was found that the Km values were similar in both cases (8 microM for transferase and 2 microM for hydrolase activities) whilst the Vmax values were lower for the fusion protein, possibly due to the presence of misfolded forms. An optical biosensor based on the resonant mirror was used to determine the binding kinetics between the fusion protein and the immobilised streptavidin. The association and dissociation rate constants were determined to be 2.1(+/-0.3) x 10(-2) microM(-1) s(-1) and 11(+/-0.2) x 10(-3) s(-1), respectively, which results in an equilibrium dissociation constant of 0.5 microM. This is larger than previously reported affinities based on titration calorimetry and may be a consequence of the presence of two streptavidin binding sequences on the dimeric alkaline phosphatase simultaneously binding to two subunits of streptavidin.

Alkaline Phosphatase↗
PubMed2002

The neuropathology observed in wild-type mice inoculated with human poliovirus mirrors human paralytic poliomyelitis.

Human paralytic poliomyelitis results from the destruction of spinal cord anterior horn motor neurons by human poliovirus (PV). CNS disease pathology similar to human poliomyelitis has been observed in experimentally infected chimpanzees, monkeys and wild-type mice. In this study we present a detailed examination of the clinical and histopathological features in the wild-type mouse after intracranial (i.c.) and novel intramuscular (i.m.) injection of poliovirus. Either route of poliovirus administration results in a clinical disease characterized predominately by flaccid paralysis. The observed histopathological features are compared with the histopathology reported for human paralytic poliomyelitis, experimentally infected chimpanzees, monkeys and transgenic mice expressing the human poliovirus receptor (hPVR). The observation of flaccid paralysis and anterior horn motor neuron destruction mirrors what is observed in human paralytic poliomyelitis. Our results suggest that the neuropathology observed in the wild-type mouse model is similar to what has been observed in both the human disease and in other experimental animal models, with the possible exception of the transgenic mouse model. The observed neuropathology of the wild-type mouse model more closely reflects what has been observed in human poliomyelitis, as well as in experimentally infected chimpanzees and monkeys, than does the hPVR transgenic mouse model. The previously reported poliovirus-induced white matter demyelinating disease was not observed.

Animals↗
PubMed1995

The "mirror image" and "two-thirds" types of hemispherical spondylosclerosis.

Clinical and radiological examination of 167 hemispherical spondylosclerosis (HSS) patients (56 male, 111 female) revealed a total of 186 cases of HSS with multiple incidences occurring in 18 patients. Radiologically these HSS cases were characterized by erosion and new bone formation at the inferior and upper end plate of the vertebra below, periosteal bone apposition or ossification of the anterior longitudinal ligament, spondylophytes, and signs of degenerative alteration of the vertebra and disc. In addition, the size and location (anterior, middle, posterior third) of each HSS in the lateral view was investigated. The cases were also investigated for reflection phenomenon between supra- and infradiscal sclerosis and for kyphotic angulation of the two adjacent vertebrae. The results showed that in 105 cases (56.5%) the HSS filled out the entire vertebral area; 97 cases (52.2%) showed a mirror-image type HSS; while in 8 cases (4.3%), the infradiscal sclerosis was polymorphic. In 81 cases (43.5%), the sclerosis was limited to the anterior two-thirds; this is termed "two-thirds" type. All 81 of these cases of HSS showed a kyphotic angulation of at least 4 degrees. Of these, 61 (32.8% of the total) showed reflection phenomenon while 20 (10.7% of the total) had polymorphic infradiscal sclerosis. Overall, 158 cases of HSS (85%) exhibited the reflection phenomenon between supra- and infradiscal sclerosis, whereas 28 cases (15%) revealed polymorphic sclerosis of the subadjacent vertebra. Kyphotic angulation was completely absent when HSS was visible in the entire vertebra. A dorsal gap of the disc space was seen in 36 cases (19.4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Magnetic stimulation study in mirror movements.

A young man with congenital mirror movements was studied by non-invasive magnetic stimulation. Radiological examination showed no craniocervical or pituitary abnormality except for mild atrophy of the right hippocampus. Magnetic stimulation of the motor cortex caused large amplitudes in the ipsilateral hand muscles, indicating the possibility of functional disorder in the motor pathways from the motor cortex to muscles in the upper extremities.

Adult↗
PubMed1986

Acute lymphoblastic leukemia hand-mirror cells with OKT 8 phenotype.

Acute lymphoblastic leukemia with hand-mirror cells (ALL-HMC) was diagnosed in a 20-year old patient. Cytochemical investigations revealed a positive reaction for PAS and acid phosphatase. Lymphoid blast cells were studied with various monoclonal antibodies in order to determine their derivation and differentiation. The data obtained (positivity for Leu 9, OKT 11 and OKT 8) suggest that blast cells were of T lineage with OKT 8 phenotype. This report supports the phenotypic heterogeneity of ALL-HMC.

Adult↗
PubMed1977

Children's response to their true and distorted mirror images.

In order to study the development of body image, 16 children aged 2 months to 8 years were tested to determine their levels of cognitive development on the basis of Piaget's theory, and their responses to their true and distorted mirror images. The study indicates a definite characteristic response by children according to their levels of cognitive development. This corresponds to infantile anxieties appropriate to the psychoanalytic theory of object relationships. The theoretical and clinical implications of the study are discussed.

Anxiety↗
PubMed1989

Aortic atresia with visceral situs inversus with mirror-image dextrocardia.

A newborn infant with situs inversus totalis (visceral situs inversus with mirror-image dextrocardia) with aortic atresia is presented. No reports of this anatomical variant have previously been reported in the literature. A brief discussion of the various types of congenital heart defects and their incidence in association with situs inversus totalis is presented.

Abnormalities, Multiple↗
PubMed2003

Audiovisual mirror neurons and action recognition.

Many object-related actions can be recognized both by their sound and by their vision. Here we describe a population of neurons in the ventral premotor cortex of the monkey that discharge both when the animal performs a specific action and when it hears or sees the same action performed by another individual. These 'audiovisual mirror neurons' therefore represent actions independently of whether these actions are performed, heard or seen. The magnitude of auditory and visual responses did not differ significantly in half the neurons. A neurometric analysis revealed that based on the response of these neurons, two actions could be discriminated with 97% accuracy.

Acoustic Stimulation↗
PubMedDate not supplied

Vascular ring due to right aortic arch with mirror-image branching and left ligamentum arteriosus: complete preoperative diagnosis by magnetic resonance imaging.

Magnetic resonance imaging (MRI) has been increasingly employed in the evaluation of aortic arch abnormalities. We present a rare form of vascular ring, that of a right aortic arch with mirror-image branching and left ligamentum arteriosus, which was clearly defined preoperatively by MRI. The patient subsequently underwent successful surgical division of the vascular ring followed by improvement in respiratory symptoms.

Aorta, Thoracic↗
PubMed2000

The 'mirrored' Bennett fracture of the base of the fifth metacarpal.

Fractures of the base of the metacarpals are usually treated conservatively. The intra-articular fracture of the base of the first metacarpal ('Bennett fracture') is an exception to this rule because inadequate repositioning and fixation of the dislocated radial fragment lead to permanent deformity of the joint and subsequent degenerative joint disease. The dislocated intra-articular fracture of the base of the fifth metacarpal is similar to a Bennett fracture in many aspects. Repositioning of this 'mirrored' Bennett fracture cannot be guaranteed by a plaster cast. Inadequate repositioning will lead to pain, reduced strength and early degenerative joint disease. We present six patients with dislocated intra-articular fractures of the base of the fifth metacarpal to illustrate the necessity of surgical reduction and fixation.

Adult↗
PubMed2001

Epaxial-adaxial-hypaxial regionalisation of the vertebrate somite: evidence for a somitic organiser and a mirror-image duplication.

During vertebrate neural tube formation, the initially lateral borders between the neural and epidermal ectoderm fuse to form the definitive dorsal region of the embryo, while the initially dorsally located notochord-floor plate complex is being internalised. Along the definitive dorso-ventral body axis, one can distinguish an epaxial (dorsal to the notochord) and a hypaxial (ventral to the notochord) body region. The mesodermal somites on both sides of the notochord and neural tube give rise to the trunk skeleton and skeletal muscle. Muscle forms from the somite-derived dermomyotomes and myotomes that elongate dorsally and ventrally. Based on gene expression patterns and comparative embryology, it is proposed here that the epaxial (dermo)myotome region in amniote embryos is subdivided into a dorsalmost and a centrally intercalated subregion. The intercalated subregion abuts to the hypaxial (dermo)myotome region that elongates ventrally via the hypaxial somitic bud. The dorsalmost subregion elongates towards the dorsal neural tube and is proposed to derive from an epaxial somitic bud. The dorsalmost and hypaxial somite derivatives share specific gene expression patterns which are distinct from those of the intercalated somite derivatives. The intercalated somite derivatives develop adaxially, i.e. at the level of the notochord-floor plate complex. Thus, the dorsalmost and intercalated (dermo)myotome subregions may be influenced preferentially by signals from the dorsal neural tube and from the notochord-floor plate complex, respectively. These (dermo)myotome subregions are sharply delimited from each other by molecular boundary markers, including Engrailed and Wnts. It thus appears that the molecular network that polarises borders in Drosophila and vertebrate embryogenesis is redeployed during subregionalisation of the (dermo)myotome. It is proposed here that cells within the amniote (dermo)myotome establish polarised borders with organising capacity, and that the epaxial somitic bud represents a mirror-image duplication of the hypaxial somitic bud along such a border. The resulting epaxial-intercalated/adaxial-hypaxial regionalisation of somite derivatives is conserved in vertebrates although the differentiation of sclerotome and myotome starts heterochronically in embryos of different vertebrate groups.

Animals↗
PubMed1998

Analysis of the human Sonic Hedgehog coding and promoter regions in sacral agenesis, triphalangeal thumb, and mirror polydactyly.

The human Sonic Hedgehog gene (SHH) is one of the vertebrate homologs related to the Drosophila segment polarity gene hedgehog. The entire coding and promoter region of the SHH gene, including 2 kb 5' of the transcriptional start site has been screened for mutations in families with autosomal dominant sacral agenesis and autosomal dominant triphalangeal thumb, two conditions previously known to be linked to 7q36. We have also studied the SHH gene in five families with mirror polydactyly associated with tibial hemimelia and in 51 unrelated patients with neural tube defects. Except for two sequence variants in exon 3, no mutations were found in these disease categories. OFF

Abnormalities, Multiple↗