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Biomedical subjects

B Johnstone

Publications and source records attributed to B Johnstone.

79 records · Page 5Linked to original sources
PubMedDate not supplied

Effective treatment of neuropsychological deficits in Sjögren's syndrome.

Primary Sjögren's syndrome (SS) is an autoimmune disorder that can manifest as central nervous system (CNS) dysfunction and include neuropsychological deficits. Given the limited information published on the cognitive deficits associated with SS, a case of SS is reported here. The primary CNS manifestations were dissociative episodes, and objectively measured neuropsychological dysfunction which was most notable in visual-spatial abilities (as measured by the WAIS-R PIQ, WMS-R Visual Memory Index, and Rey Complex Figure) and in left-sided coordination (as assessed by the Lafayette Grooved Pegboard). Clinical symptomatology and cognition improved following therapy with high-dose corticosteroids.

Journal Article↗
PubMedDate not supplied

High variability in rabbit bone marrow-derived mesenchymal cell preparations.

The rabbit has been extensively used for preclinical models, especially in orthopedic applications. One of the more troubling features of this model is the high interindividual variability that is encountered and that requires a careful experimental design with sufficient sample size to make judgments valid. We have processed 241 individual preparations of rabbit bone marrow-derived mesenchymal progenitor cells (MPCs) over the last 3 years and have kept detailed records of the performance of these cells in various assays. This communication details the lack of correlation between the analyzed parameters. Bone marrow was harvested from 4-month-old rabbits; the cells were centrifuged, resuspended, and cultured. When cells reached 80% of confluence, they were removed from the plates with trypsin and assayed for their osteo- and chondrogenic potential. The average yield of the 241 individual MPC preparations exhibited a coefficient of variation of 77. An in vivo implantation assay with porous calcium phosphate ceramic cubes exhibited scores with a coefficient of variation of 65. Lastly, an in vitro assay of alkaline phosphatase enzyme activity exhibited the most variability with a coefficient of variation of 132. All of the cell preparations tested in an in vitro aggregate culture assay underwent chondrogenic differentiation. No relationships between any of these parameters were found. The variability of the results within the different assays is interpreted to be the result of the heterogeneity of the preparations. The lack of correlation between the parameters studied shows the importance of the conditions intrinsic to the different assays. These results serve to emphasize that any experimental design involving rabbit progenitor cells must include a sufficiently large sample size to allow statistically significant and rigorous conclusions.

Alkaline Phosphatase↗
PubMedDate not supplied

Extent of cognitive decline in traumatic brain injury based on estimates of premorbid intelligence.

Global cognitive impairment following traumatic brain injury (TBI) is common, with some abilities more significantly affected than others. However, due to difficulties in estimating premorbid intelligence, there has been no systematic evaluation of the extent of decline in different cognitive abilities following TBI. Recent studies indicate that the Wide Range Achievement Test-Revised (WRAT-R) Reading subtest is an accurate estimate of premorbid intelligence, suggesting that post-TBI cognitive test scores can be compared to the WRAT-R to estimate the extent of decline that occurs in specific cognitive abilities. The current study estimated the extent of deficit in intelligence, memory, attention, speed of processing, and cognitive flexibility for 97 outpatients with TBI. Extent of decline was calculated by subtracting WRAT-R z-scores from cognitive test z-scores to determine a z-difference score (ZDiff) for each cognitive ability. The results suggest that intelligence is least declined following TBI (WAIS-R 3-4-point decline; VIQ ZDiff = -0.23: FIQ ZDiff = -0.27), followed by attention (WMS-R 5-point decline; ZDiff = -0.31), memory (WMS-R 6-9-point decline; Verbal Memory ZDiff = -0.41; General Memory ZDiff = -0.51; Delay Memory ZDiff = -0.57), speed of processing (Trails A 15-16 second decline; ZDiff = -1.90) and cognitive flexibility (Trails B 35-52 second decline; ZDiff = -2.65). Implications for provision of feedback to individuals with TBI and their families are discussed.

Adolescent↗
PubMedDate not supplied

Immunohistochemical study of a chondroitin-6-sulfate in growth plates of broiler chickens with high and low genetic predispositions to tibial dyschondroplasia.

The distribution of a chondroitin-6-sulfate (C6S) epitope, which is a biochemical marker of chondrocyte hypertrophy, was studied in the growth plates of two lines of 3-week-old broiler chickens with low and high genetic predispositions to tibial dyschondroplasia (TD). Ultrathin sections of growth plates from both groups were subjected to immunolocalization with monoclonal antibody 3-B-3(-), the epitope of which is increased on proteoglycans made by hypertrophic chondrocytes. Bound antibody was localized with colloidal gold-labeled protein A for observation with an electron microscope. The 3-B-3(-) epitope was localized in pericellular and interterritorial matrix of growth plates of both lines. In the low-TD-incidence birds, the concentration of 3-B-3(-) bound to C6S progressively increased from the proliferative zone to the hypertrophic zone. However, in the high-TD-incidence line, the epitope expression remained at a low level in all zones. The increase of the 3-B-3(-) epitope produced by maturing growth-plate chondrocytes is indicative of changes in the glycosaminoglycan chains of proteoglycans that may be important in the process of matrical calcification. Thus, failure of chondrocytes of the high-TD-incidence line to produce this change in post-translational modification of their proteoglycans could be important in the pathological process.

Animals↗