Biomedical subjects

J L Berry

Publications and source records attributed to J L Berry.

75 records · Page 5Linked to original sources

PubMedDate not supplied

Selection of high-affinity and high-specificity monoclonal antibodies for 1 alpha,25-dihydroxyvitamin D.

The preparation of high-affinity and high-specificity monoclonal antibodies to 1 alpha,25-dihydroxyvitamin D is described. Monoclonal antibodies were derived from Balb-c mice immunised with either 1 alpha-hydroxy-25,26,27-trinor-24-cholecalcioic acid or with 1 alpha-hydroxy-26,27-dinor-cholecalciferol-25-oxime, and spleen cells were hybridised with mouse myeloma cells. From six fusions nine monoclonal antibodies (MAb's) were selected from 676 antibody-secreting hybrids. Antibodies varied widely in their ability to bind 1 alpha,25-dihydroxyvitamin D3 (50% displacement of radioligand ranged from 25 - 900 pg); two had particularly useful characteristics for 1 alpha,25-dihydroxyvitamin D assay. MAb 5F2 has high affinity (Ka = 1.39 X 10(10) M-1) and does not discriminate between 1 alpha,25-dihydroxyvitamin D2 and D3, thus enabling the two forms to be measured together. MAb 1G7 is highly specific, having no cross-reactivity with 25-hydroxy-, 24,25-dihydroxy- or 25,26-dihydroxyvitamin D at concentrations found in normal human serum; this MAb has the potential to eliminate the lengthy extraction procedures involved in currently available assays for 1 alpha,25-dihydroxyvitamin D.

Animals↗

PubMedDate not supplied

A method to evaluate the elastic behavior of vascular stents.

PURPOSE: To develop a simple method for determining the elastic behavior of vascular stents. MATERIALS AND METHODS: An experimental apparatus was constructed to determine the elastic behavior of four different vascular stents. Each stent was expanded within an artificial compliant vessel and was subjected to an increasing external pressure. The cross-sectional area of each stent was recorded at incremental changes in pressure. Compliance was estimated from the slope of a linear regression analysis fit to the pressure-area data in the elastic range of deformation. RESULTS: The self-expandable stents were the most compliant, and balloon-expandable stents exhibited the least compliance. The balloon- expandable stents initially deformed in an elastic manner and then yielded irrecoverably at higher pressures. CONCLUSION: A simple method has been devised that allows the elastic behavior of stents to be assessed. Quantification of stent compliance with this method is important as a predictor of stent resistance to compression in vivo.

Biomechanical Phenomena↗

PubMedDate not supplied

Effects of vascular stent surface area and hemodynamics on intimal thickening.

PURPOSE: To compare the in vivo response to a new mechanically expandable vascular stent with the response to an existing type of balloon-expandable stent. MATERIALS AND METHODS: Prototype stents were deployed by means of a balloon catheter in the left iliac arteries of four healthy dogs. Palmaz stents were deployed in the contralateral iliac arteries to act as a control, and all stents were explanted after 6 weeks. Arteriography was performed at the time of insertion and before harvest, and pressure gradients were measured across each stent. The stents were then harvested and submitted for histologic examination. RESULTS: The performance of the prototype stent was similar to that of the Palmaz stent with respect to structural integrity, migration, maintenance of intraluminal diameter, ease of deployment, radiopacity, and pressure gradients. Unlike the Palmaz stent, the prototype stent did not foreshorten during expansion. The stents showed a lack of uniformity in terms of the measured luminal area and neointimal accumulation. Neointimal accumulation was more confined to the struts of the prototype stent; the lumen therefore had a fluted appearance. Neointimal accumulation was more broadly distributed around the circumference of the vessel wall of the Palmaz stent. CONCLUSION: In vivo performance of the prototype stent was similar to that of the Palmaz stent. Stent geometry may be an important determinant of neointimal response and resultant long-term patency.

Angiography↗