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Biomedical subjects

C Barry

Publications and source records attributed to C Barry.

At least 37 records · Page 2Linked to original sources

Modelling assembled spelling: convergence of data from normal subjects and "surface" dysgraphia.

A model of assembled spelling proposed by Barry and Seymour (1988, Quarterly Journal of Experimental Psychology), based upon normal subject's spelling of nonwords, is presented. Predictions concerning surface dysgraphic spelling are derived from this model, and are compared against the performance of the patient recently reported by Baxter and Warrington (1987, Cortex). Although the model's expectations are broadly confirmed, Baxter and Warrington's data suggest that an adequate model of assembled spelling requires further specification, particularly in two areas: how sound-to-spelling correspondences are established, and how context-sensitivity constraints (or multiple unit correspondences) operate.

Humans

Expression and localization of myelin basic protein in oligodendrocytes and transfected fibroblasts.

Myelin basic protein (MBP) is a major structural component of myelin. It is expressed exclusively in myelinating glia (oligodendrocytes in the CNS and Schwann cells in the PNS) and is localized to the cytoplasmic surface of the plasma membrane and myelin membrane produced by these cells. The work described here concerns the mechanism of plasma membrane localization of MBP in myelinating glial cells and whether it involves differentiated functions specific to these cells or general functions of plasma membrane assembly common to all cells. To this end, the subcellular localization of endogenous MBP in mouse oligodendrocytes was compared with that of transiently expressed MBP in monkey fibroblasts (Cos-1 cells) transfected with an MBP expression vector containing cDNA for rat 14K MBP. The steady-state levels of MBP-specific RNA and of MBP polypeptide expressed in the transfected fibroblasts were comparable to the levels expressed in oligodendrocytes in primary culture. MBP localization was analyzed in whole cells by immunofluorescence and in specific intracellular compartments by subcellular fractionation. The results show that MBP expressed in wild-type oligodendrocytes is localized to the plasma membrane. In contrast, MBP expressed in transfected fibroblasts appears dispersed in the cytoplasm and is distributed uniformly among the various subcellular fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

Computerised densitometry of red-free retinal photographs correlated with automatic perimetry.

An image analyser installed in a 16 bit personal computer was used to measure grey levels in red free photographs of normal and glaucomatous eyes. Regional photographic image intensity and density were correlated with Humphrey Field Analyser results for corresponding areas of visual field. Two methods for standardising photographic exposure by histogram equalisation and slide were compared in two groups of eyes from 13 subjects. For histogram equalisation, r2 varied from 0.16 to 0.29 for linear fits in temporal retinal quadrants. For the histogram slide, r2 varied between 0.19 to 0.45 for linear fits. Similar results were found for mean histogram equalised image intensity versus Humphrey Field Analyser global indices: Mean Deviation, (r2 = 0.27) and Pattern Standard Deviation, (r2 = 0.37). For histogram equalised image data, resistant line analysis showed a linear goodness of fit of 0.92 and for histogram slide goodness of fit was 0.97 for upper and 0.87 for lower temporal quadrants.

Color

Anticardiolipin antibodies in rheumatoid arthritis.

Anticardiolipin antibody (ACA) was present in the sera of 49% of 90 consecutive patients with rheumatoid arthritis (RA). The ACA was absent in 30 control patients with osteoarthritis. C-reactive protein levels equal to or exceeding 7 mg/dl were found in 10 patients all of whom were ACA positive. ACA was present in a larger proportion of rheumatoid factor (RF) positive than of RF negative patients. Male sex and extra-articular manifestations of RA were both more common in ACA positive than ACA negative patients. In the ACA positive group the lupus anticoagulant and VDRL tests were negative. However, a small number of patients had evidence of vascular events.

Adult

Lymphoid irradiation in intractable rheumatoid arthritis. A double-blind, randomized study comparing 750-rad treatment with 2,000-rad treatment.

Twenty patients with intractable rheumatoid arthritis were treated with 750-rad or 2,000-rad lymphoid irradiation in a randomized double-blind comparative study. Over a 12-month followup period, there was a significant improvement in 4 of 7 and 6 of 7 standard parameters of disease activity following treatment with 750 rads and 2,000 rads, respectively. Transient, short-term toxicity was less frequent with the lower dose. In both groups, there was a sustained peripheral blood lymphopenia, a selective depletion of T helper (Leu-3a+) lymphocytes, and reduced in vitro mitogen responses. These changes did not occur, however, in synovial fluid. These results suggest that 750-rad lymphoid irradiation is as effective as, but less toxic than, that with 2,000 rads in the management of patients with intractable rheumatoid arthritis.

Adult

Psychiatric disorder among boys with Duchenne muscular dystrophy.

The prevalence of psychiatric disorder in 23 boys with Duchenne muscular dystrophy was assessed and compared to a matched control group. Dysthymic disorder and major depressive disorder occurred significantly more often among DMD boys than controls. Older boys with DMD were at greater risk of depressive disorder than younger boys. Possible aetiological factors and approaches to management are discussed.

Adolescent

Communication within families about Duchenne muscular dystrophy.

An interview with parents of 23 boys with Duchenne muscular dystrophy (DMD) suggested that communication within families about the disorder presented difficulties for both parents and the boys. Spouses rarely discussed the condition and for many this was not a problem area but a way of coping by dealing only with the present. More problematic was the inability for parents and affected boys to communicate about the disorder. Lack of communication occasionally was responsible for carriers not being informed about the genetic nature of the disorder. Possible reasons for these patterns of communication are discussed and some approaches to helping families of boys with DMD are suggested.

Adolescent

Phonological dyslexia, lexical analogy, and functional models of oral reading: a critique of Bradley and Thomson.

We discuss some of the interesting features of the investigation of a phonological dyslexic patient's ability to read aloud nonwords embedded in words reported by Bradley and Thomson (1984, Brain and Language, 22, 292-302). We highlight some problems of their interpretation, tentatively suggest an alternative explanation in terms of lexical analogy, and conclude by suggesting some prescriptive conditions for the legitimacy of extending models of normal functioning to account for cognitive neuropsychological data.

Dyslexia, Acquired

Familiarity decisions for faces presented to the left and right cerebral hemispheres.

Right-handed subjects were asked to decide whether or not faces presented briefly in the RVF or in the LVF were familiar (familiar faces were those of famous people). This task avoids the need for extensive semantic processing or temporary storage involved in conventional naming or identification tasks, and thus eliminates the contribution of such factors to any observed asymmetry. The resulting finding of faster reaction times to LVF faces, with no overall visual hemifield difference in error rates, is taken to indicate a right-hemisphere superiority either in the processes used to construct facial representations or in the accessing of face recognition units, or both.

Adult

The role of vasopressin in experimental and clinical hypertension.

The vasoconstrictor and vasopressor actions of vasopressin have been revealed in recent research through the use of highly specific and sensitive radioimmunoassays, employment of peptide antagonists, and comparison with an animal model which has hereditary absence of this hormone, the Brattleboro rat. Factors now known to modify the pressor effect of vasopressin are the baroreflexes, local vascular prostaglandin production, and a specific interaction with angiotensin II. In experimental models the volume retaining, but not the vasoconstrictor effect of vasopressin is necessary for mineralocorticoid-salt hypertension. Vasopressin contributes directly to the increase in arterial pressure of glycerol induced acute renal failure. In nephrectomized rats, plasma vasopressin is elevated and contributes directly to maintenance of pressure. Vasopressin antagonism may reduce arterial pressure in Goldblatt 1 and 2 kidney hypertension and in one genetic model, spontaneously hypertensive rat (SHR), but the peptide is not necessary for hypertension in these models. Plasma vasopressin is reduced in primary aldosteronism, but may be elevated in malignant hypertension. In essential hypertension, there is considerable disagreement among various studies in which plasma vasopressin, urine vasopressin excretion, platelet associated vasopressin, or vasopressin-neurophysin were measured as to whether there is evidence for increased secretion of vasopressin. Only preliminary studies of vasopressin antagonism in clinical hypertension have been reported. At present, there is no conclusive evidence that elevated vasopressin secretion occurs or is necessary for any form of clinical hypertension.

Acute Disease

Direct immunofluorescence of normal skin in rheumatoid arthritis.

The clinical significance of previously described immunoglobulin and complement deposition in the superficial dermal vessel walls of patients with rheumatoid arthritis is unknown. In the present study, skin biopsies were obtained from the normal forearm and buttock of 48 unselected patients with rheumatoid arthritis and were examined by direct immunofluorescence (IF) for the presence of immunoglobulin (IgG,A,M) and complement (C3) in the vessel walls. Deposits of C3, IgM or IgG were detected in 10 patients. Five patients had deposits at the forearm sample alone, four patients had deposits at both biopsy sites, while one patient was positive at the buttock alone. Clinical features were similar in patients with and without vessel IF. However, patients with IF were significantly more seropositive with lower levels of complement and raised levels of serum IgA and IgM. There was also an increased level of circulating IgG immune complexes in these patients. Further analysis following exclusion of seronegative patients revealed similar results. This study suggests that the presence of vessel IF identifies a subgroup of patients who have evidence of more severe immunological disturbance.

Antibodies

Hemispheric asymmetry in face perception tasks of different cognitive requirement.

Three laterality experiments using tasks of different cognitive requirement were performed in order to determine the stage at which hemispheric differences in face perception arise. All experiments employed the same set of faces and a vocal reaction time paradigm. In experiment 1, subjects were required to discriminate male from female faces and no hemispheric asymmetries were found. In experiment 2, subjects were required to decide whether or not faces were of famous or unknown people and a right hemisphere advantage was found. Finally, in experiment 3 subjects were required to verbally identify the famous faces and no hemispheric differences were found. The results suggest that a right hemisphere superiority exists for the comparison of stimulus faces with an internal representation. Contrary to expectation, face naming does not result in a selective left hemisphere involvement.

Adult