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Biomedical subjects

J Barratt

Publications and source records attributed to J Barratt.

9 recordsLinked to original sources
PubMed1992

Putative immunolocalization of the mechanoelectrical transduction channels in mammalian cochlear hair cells.

Hair cells bear an apical bundle of stereocilia arranged in serried rows. Deflection of the bundle controls the opening and closing of mechanoelectrical transduction channels, thereby altering the conductance across the apical plasma membrane. Two locations for these channels have been proposed in the bundle, either near the bases of the stereocilia or towards their tips. One hypothesis that is consistent with the latter possibility suggests that fine extracellular filaments, which run between the tips of the shorter stereocilia and the sides of the taller stereocilia behind, operate the channels. Determining the precise position of the channels is essential to test this hypothesis. We have therefore attempted to localize them immunocytochemically. Because hair-cell transduction is amiloride sensitive, the channels may have an amiloride-binding site associated with them. We have therefore used a polyclonal antibody raised against another amiloride-sensitive ion channel to hunt for them. This antibody recognizes a 62-64 kDa band in immunoblots of cochlear tissue, and produces discrete labelling in the hair bundle. This is most concentrated just below the tips of the shorter stereocilia, coinciding with a region of specialization in the closely apposed membranes of the short and tall stereocilia but not with either end of the tip link.

Amiloride↗
PubMed1992

Trial of intensive compared with weekly speech therapy in preschool children.

Forty two preschool children referred to a speech therapy department were randomly allocated to receive intensive individual speech therapy or the more traditional once weekly approach. Boys and minority ethnic groups were referred most frequently. Speech therapy improved expression more than comprehension, as measured on Reynell scales. The mean improvements were 0.5 SDs (95% confidence intervals (CI) 0.3 to 0.7) and 0.3 (95% CI 0.1 to 0.5) respectively. There was a greater improvement in children receiving intensive compared with weekly therapy in the expression scores (0.8 SDs (95% CI 0.5 to 1.1) v 0.2 SDs (95% CI -0.1 to 0.5]. White and non-white children had similar improvements in comprehension scores but white children had greater improvement in expression scores (1.1 SDs v 0.3 SDs). This difference was seen in both therapy groups. Randomised trials are useful in the evaluation of speech therapy in children.

Child, Preschool↗
PubMed1986

Metabolic activity of erosions in rheumatoid arthritis.

The hands of 10 patients with rheumatoid arthritis were investigated with diphosphonate scanning and radiology. Increased uptake of isotope can be associated with some erosions but not all and also reflects other processes more linked to acute inflammatory areas unassociated with the development of erosions. If the latter are the hallmark of active rheumatoid arthritis then bone scans are not.

Adult↗
PubMed1979

A simple radiolabelled rheumatoid factor binding assay for the measurement of circulating immune complexes.

A simple assay for circulating immune complexes has been developed and the optimal conditions for reaction defined. Partially purified radiolabelled polyclonal or monoclonal rheumatoid factor was incubated with aggregated IgG or soluble immune complexes and the resultant macromolecule precipitated with 3% polyethylene glycol. Monoclonal rheumatoid factor was much the better reagent, allowing the detection of approx. 0.35microgram/ml or more of aggregated IgG. Soluble immune complexes formed in vitro at between x2--x20 antigen excess were detectable over a wide range of molecular size. Clinical studies indicated that the assay is a useful addition to the currently available techniques for measuring circulating immune complexes.

Antigen-Antibody Complex↗
PubMed1977

Classical pathway complement activation in association with paraproteinaemia.

Five of twenty-three patients with paraproteinaemia (two IgM, three IgG) have been shown to exhibit marked classical pathway complement activation. The mechanisms of hypocomplementaemia proposed for the five patients are cryoglobulinaemia in one and in vivo immunoglobulin aggregation in the other four. Three further patients had a low C1q and three a low C3 unassociated with any other complement abnormality. No association with any particular IgG subclass or obvious clinical abnormality existed in association with hypocomplementaemia.

Complement C1↗