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N Kraft

Publications and source records attributed to N Kraft.

48 records · Page 3Linked to original sources
PubMed1972

Differentiation of antibody-forming cells in toad spleen. A study using density and sedimentation velocity cell separation.

Antibody-forming cells (AFC), developing in toad spleen after stimulation with polymerized flagellin, were studied with an immune adherence assay. Differentiation was followed by several parameters: thymidine uptake to monitor dividing cells; equilibrium density centrifugation in albumin gradients to monitor cell density; microscopic measurements and sedimentation velocity separation to monitor cell size; stained preparations to follow cell morphology. Almost all AFC observed early in the response were dividing cells; the proportion of dividing AFC dropped to 4% 2 wk after stimulation. The earliest AFC detected (3 days) formed a relatively homogeneous light density population, and were purified 17-fold by equilibrium density centrifugation. As the response developed, additional denser peaks were found, so that late in the response dense AFC predominated. Dividing AFC were confined to the light density region throughout the response. Cell diameter measurements revealed that the earliest AFC were all very large cells. In a manner analogous to the density changes, smaller AFC appeared as the response developed until they finally comprised the majority of the AFC population. Dividing AFC were always relatively large, but encompassed a wide range of sizes. Sedimentation velocity separation was employed in a closer study of the immature AFC; they were purified 140-fold by this procedure. The earliest AFC consisted of several readily separable size populations in the range 9-18 micro diameter. The presence of separate peaks related by factors of two in volume suggested that the largest cells undergo a series of halving divisions before entering a division growth cycle. The results suggest an AFC differentiation sequence from a very large, light density, dividing "blast" cell to a nondividing cell with the size, density, and morphological appearance of a small lymphocyte. Stages of this sequence can be defined and selected out for investigation, using sedimentation velocity and equilibrium density centrifugation as complementary techniques.

Animals↗
PubMedDate not supplied

[Surgical outcome of single segment ventral fusion with plate osteosynthesis in therapy refractory chronic cervico-brachialgia].

INTRODUCTION: In anterior cervical stabilization, collapses of the grafted bone with resulting localized kyphosis and graft dislocation has been reported. It was the aim of this clinical trial to evaluate the benefit of additional plating while taking specific implant-related complications into account. METHODS: The results of single level anterior cervical spinal fusion were evaluated. In 44 patients suffering from chronic cervical radicular pain with degenerative changes, arthrodesis with iliac-crest bone and plate fixation was performed. Apart from clinical parameters, the pre- and postoperative segmental kyphosis and cervical lordosis were evaluated. RESULTS: The total cervical alignment increased from 15.4 degrees to 18.5 degrees while the alignment of the fused segment increased from 2.6 degrees to 7.7 degrees. Postoperative decrease of correction did not occur. Bony fusion was confirmed in 95% after 12 months and 100% aller 36 months. Our results show that patients had more relief from radicular pain (80%) than from unspecific neck pain (66%). DISCUSSION: In single level anterior cervical fusion, additional plating successfully prevents dislocation of the bone graft and postoperative kyphosis. The clinical results and pseudarthrosis rate do not differ from studies without plating. Long. term follow-up studies are necessary to show the benefit of the reduced postoperative kyphosis.

Bone Plates↗