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At least 73 records · Page 4Linked to original sources
PubMed1979

Spatial localization under conflict conditions: is there a single explanation?

Visual--auditory (VA) and visual--proprioceptive (VP) localization conflict paradigms were varied to explore the comparability of the conflict situations. In experiment 1 various attempts were made to decrease the dominance of visual information over proprioceptive and auditory target information. Pairing auditory with proprioceptive information against conflicting visual information did not lessen the visual dominance, nor did dimming the visual field. A 'cognitive' manipulation, in which the subject was led to doubt the reliability of the visual information, reduced visual dominance over audition but not visual dominance over proprioception. This difference between the two conflict situations was further explored and corroborated in experiment 2. In experiment 3 no attempt was made to lead the subject to believe that paired discrepant targets were related, and the visual dominance of audition was strong while the visual dominance of proprioception did not occur. The apparent differences between the VA and VP conflict situations are discussed with regard to the feability of generating a unitary explanation of localization conflict results. Several further factors are discussed that must be explored before undertaking such a unitary formulation.

Cognition↗
PubMed1988

Spatially localized 1H NMR spectra of metabolites in the human brain.

Using a surface coil, we have obtained 1H NMR spectra from metabolites in the human brain. Localization was achieved by combining depth pulses with image-selected in vivo spectroscopy magnetic field gradient methods. 1H spectra in which total creatine (3.03 ppm) has a signal/noise ratio of 95:1 were obtained in 4 min from 14 ml of brain. A resonance at 2.02 ppm consisting predominantly of N-acetylaspartate was measured relative to the creatine peak in gray and white matter, and the ratio was lower in the white matter. The spin-spin relaxation times of N-acetylaspartate and creatine were measured in white and gray matter and while creatine relaxation times were the same in both, the N-acetylaspartate relaxation time was longer in white matter. Lactate was detected in the normoxic brain and the average of three measurements was approximately equal to 0.5 mM from comparison with the creatine plus phosphocreatine peak, which was assumed to be 10.5 mM.

Algorithms↗
PubMed1991

Identification, characterization, and spatial localization of two flagellin species in Helicobacter pylori flagella.

Flagellar filaments were isolated from Helicobacter pylori by shearing, and flagellar proteins were further purified by a variety of techniques, including CsCl density gradient ultracentrifugation, pH 2.0 acid disassociation-neutral pH reassociation, and differential ultracentrifugation followed by molecular sieving with a Sephacryl S-500 column or Mono Q anion-exchange column, and purified to homogeneity by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transfer to an Immobilon membrane. Two flagellin species of pI 5.2 and with apparent subunit molecular weights (Mrs) of 57,000 and 56,000 were obtained. N-terminal amino acid analysis showed that the two H. pylori flagellin species were related to each other and shared sequence similarity with the N-terminal amino acid sequence of Campylobacter coli, Bacillus, Salmonella, and Caulobacter flagellins. Analysis of the amino acid composition of the predominant 56,000-Mr flagellin species isolated from two strains showed that it was comparable to the flagellins of other species. The minor 57,000-Mr flagellin species contained a higher content of proline. Immunoelectron microscopic studies with polyclonal monospecific H. pylori antiflagellin antiserum and monoclonal antibody (MAb) 72c showed that the two different-Mr flagellin species were located in different regions of the assembled flagellar filament. The minor 57,000-Mr species was located proximal to the hook, and the major 56,000-Mr flagellin composed the remainder of the filament. Western immunoblot analysis with polyclonal rabbit antisera raised against H. pylori or Campylobacter jejuni flagellins and MAb 72c showed that the 56,000-Mr flagellin carried sequences antigenetically cross-reactive with the 57,000-Mr H. pylori flagellin and the flagellins of Campylobacter species. This antigenic cross-reactivity did not extend to the flagellins of other gram-negative bacteria. The 56,000-Mr flagellin also carried H. pylori-specific sequences recognized by two additional MAbs. The epitopes for these MAbs were not surface exposed on the assembled inner flagellar filament of H. pylori but were readily detected by immunodot blot assay of sodium dodecyl sulfate-lysed cells of H. pylori, suggesting that this serological test could be a useful addition to those currently employed in the rapid identification of this important pathogen.

Amino Acid Sequence↗
PubMed1991

[Experience with more than 200 cases of breast biopsy after preoperative spatial localization without radiostereotaxic equipment].

The use of mammography as a screening examination has considerably increased our ability to detect non-palpable breast lesions less than 1 cm phi. A conclusive diagnosis frequently requires surgical biopsy. However, breast lesions can be localized prior to surgical biopsy by placing a wire in the lesion, with/without the use of stereotaxic equipment. Our method for lesion localization consisted in acquiring two orthogonal radiographs (cranio-caudal and latero-lateral) centered on the nipple. We used 20-21 G needles, 6-10 cm long, with curved-end wire. Mammographic findings possibly suggesting cancer were: microcalcifications, nodules, spiculated opacities, and architectural distortions. From January 1987 to January 1990, 223 patients were submitted to needle localization of breast lesions under mammographic guidance and without stereotaxic equipment. Sixty-seven cases (30%) were positive for malignancy, with a 2.3:1 benign/malignant ratio. Patients' age ranged 30-70 years, but most of them were 50-60 years old. No significant complications were observed: in one case only the hook wire broke, within breast parenchyma, which was at any rate resected together with the surgical specimen.

Adult↗
PubMedDate not supplied

[Accuracy of the spatial localization of the sources of brain bioelectrical activity in a model homogeneous unrestricted environment].

The possibility is considered of use of the model of homogeneous unlimited medium (HUM) for localization of sources of brain bioelectrical activity at recording of electric potentials on its surface. It is shown that when the recording electrodes are arranged in accordance with 10-20 system, the source localization error does not exceed 10% of the head radius practically in any position of the source. A significant dependence is revealed of the source localization error on the concrete electrodes system used in experiment. It demands careful treatment of the available general recommendations on correction of the position of the source found by HUM model without consideration of the concrete arrangement of recording electrodes.

Brain↗
PubMed1987

Recession vs marginal myotomy surgery for strabismus: effects on spatial localization.

Palisade endings (PEs) are found at the musculotendinous junction in eye muscles and this is the site of much strabismus surgery. To assess the role of PEs in supplying proprioceptive information about eye position, we compared the effects of marginal myotomy and recession surgeries on tests of eye-hand coordination (open-loop pointing responses) taken before and after surgery in two groups of children having medial rectus weakening procedures for the first time. The results indicate that the myotomy is more proprioceptively "de-afferenting" than the recession, and we assume this is due to the greater disruption of PEs in this procedure.

Child↗