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Biomedical subjects

R Nowygrod

Publications and source records attributed to R Nowygrod.

65 records · Page 4Linked to original sources
PubMed1976

B cell ontogeny in rabbits. Immunofluoresecent localization of B cells in fetal and neonatal rabbits.

The mammalian equivalent of the Bursa of Fabricius, the organ responsible for B cell maturation in avian species, has not been identified despite anatomic and ablative studies which suggest that the gut-associated lymphoid tissues (GALT) subserve this function. By analogy to the Bursa, the mammalian organ directing B cell ontogeny should be the site where IgM-bearing cells (B cells) are first identifiable. In this study, fluorescein-tagged heavy chain specific antirabbit IgM is used to localize initial sites of B cell appearance in rabbit fetal and neonatal lymphoid tissues. IgM-bearing cells are found 2 days before birth in the thymus and 1 day before birth in GALT. Immunoglobulin-bearing cells in spleen, lymph node, and bone marrow are undetectable until after birth. B cells bearing the IgM marked precede the appearance of IgG-bearing cells by 1 to 4 days in all instances. Intraperitoneal implantation of Millipore chambers containing immature fetal thymic tissue into neonatal hosts reveals that in situ development of IgM cells takes place independent of host cell traffic. The results suggest that B cell ontogeny in mammals is more complex than in avian species and demonstrates probable involvement of the thymus in the maturational process.

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PubMedDate not supplied

Photo-oxidized bovine arterial grafts: short-term results.

Biologic grafts are the conduit of choice for vascular reconstructive procedures. The short-term thrombogenicity, patency, and stability of bovine arterial grafts, altered by a dye-mediated photo-oxidation process, was evaluated in the canine common femoral vein (CFV) and artery (CFA) model. Modified bovine interposition grafts were implanted in the CFV of 12 dogs and in the CFA of 11 dogs, respectively. Polytetrafluoroethylene (PTFE) implants on the contralateral side served as controls. Patency and histology were assessed at 1, 2, 4, and 6 weeks. In the CFV, patency of photo-oxidized grafts was 83% at 1 week and 71% at 2 weeks, compared to 17% and 0% for PTFE, respectively (p = 0.0033). In CFA, patency was 82% for the photo-oxidized graft and 63% for PTFE at 6 weeks (p = NS). Photo-oxidized grafts were nonreactive, without evidence of degenerative changes or cellular infiltration at all time periods. Compared to commercially available PTFE, photo-oxidized arterial grafts have superior patency in the CFV, and comparable patency in the CFA. Preliminary results demonstrate that these xenografts are stable and without degenerative changes. If corroborated by long-term data, these grafts may be a suitable alternative to currently available prosthetics for peripheral vascular reconstructive procedures.

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PubMedDate not supplied

Femorofemoral bypass for unilateral iliac artery occlusion in the presence of bilateral superficial femoral artery occlusions.

The femorofemoral bypass has become a popular technique of reconstruction for unilateral iliac artery occlusion because of low morbidity and excellent long-term patency. A "steal phenomenon" is infrequently seen, but even in relatively sedentary patients with limb-threatening ischemia femorofemoral grafting has been associated with severe donor limb ischemia in occasional instances. This report describes five high risk elderly patients who underwent femorofemoral bypass for limb-threatening ischemia due to unilateral iliac artery occlusion in association with bilateral superficial femoral artery occlusions. All patients underwent successful bypass as judged by relief of rest pain and healing of ulcerations. Despite a pre-operative resting donor limb mean ankle/brachial index of .45, there was no deterioration of donor limb perfusion when patients were followed for a mean of 15.6 months. It is concluded that femorofemoral bypass is the procedure of choice for limb salvage in poor risk patients with adequate donor limb inflow regardless of the degree of outflow occlusive disease.

Aged↗
PubMedDate not supplied

Efficacy of percutaneous angioplasty in lower extremity arterial occlusive disease.

One hundred and twenty four percutaneous transluminal angioplasties performed over a 5 year period for lower extremity arterial occlusive disease were reviewed to evaluate clinical efficacy and define parameters of success. Technical success was achieved in 82%, clinical success in 71%. The important predictive variables were severity of disease, anatomic site and length of diseased vessel segment. Best results (94% success rate) were obtained in the proximal single segment lesion with lesser initial disease as reflected by flow study, calf vessel runoff and claudication as the indication for treatment. The poorest results (33% success rate) were obtained in distal vessels with multisegmental disease where limb salvage was the indication for intervention. Stenosing or recently occluded bypass grafts were successfully dilated in 7 of 8 patients. With a complication rate of 3%, percutaneous angioplasty is clearly a highly effective treatment for lower extremity arterial insufficiency in the properly selected patient judged by immediate and relatively short term follow-up observations.

Aged↗
PubMedDate not supplied

The prognostic value of the noninvasive vascular laboratory in autologous vein bypasses of the lower extremities.

A retrospective study of 34 patients with 29 autologous vein femoropopliteal and 8 femorotibial bypasses was conducted, examining the correlation of angiographic runoff and non-invasive flow determinants as prognostic indicators of early graft occlusion of lower limb bypass grafts. The followup period was 3-27 months, with a mean of 5.8 months. Graft patency and improvement in presenting symptoms were unrelated to preoperative ankle systolic pressure indices. Preoperative and postoperative flow measurements were similar in patients with patent grafts (greater than 12 months) and in those with early graft occlusion (0-6 months, p greater than .05). Preoperative pressure indices did not correlate with calf vessel runoff (p. greater than 05). The data suggest: (1) the noninvasive flow studies are not reliable predictors of future graft patency, (2) vessel runoff is not a reliable predictor of limb flow, and (3) bypass procedures in the lower extremities should not be excluded on the basis of noninvasive flow studies when indicated by other clinical parameters.

Adult↗
PubMedDate not supplied

Selective anticoagulation with active site blocked factor IXa in synthetic patch vascular repair results in decreased blood loss and operative time.

Heparin has been the mainstay of anti thrombic therapy in arterial repair procedures. With increasing use of synthetic patch angioplasty (polytetrafluoroethylene [PTFE] or Dacron, Medical Products, Flagstaff, AZ) to improve long-term patency and limit aneurysmal dilation, however, the use of heparin has been associated with excessive needle hole bleeding, resulting in time delay in the operating room to achieve hemostasis, as well as clinically significant blood loss. Because of the multiple sites of action of heparin in the coagulation cascade, both intravascular (desired effect) and extravascular (untoward side effect) hemostasis are impaired. The authors therefore tested the hypothesis that selective inhibition of intravascular coagulation, without significant impairment of extravascular hemostasis, would prevent clotting intraluminally while preserving hemostasis at the suture line of the patch graft. The unique position of factor IX/IXa in the coagulation cascade renders its inhibition an ideal target in this setting. The authors prepared active site blocked factor IXa (IXai) using dansyl-Glu-Gly-Arg chloromethylketone, and tested this hypothesis in a New Zealand rabbit aortotomy model with PTFE patch closure using either heparin (25 i.u./kg; n = 16) or IXai (300 micrograms/kg; n = 21). The infrarenal aorta was identified and isolated, the anti coagulant infused, aortic cross clamp placed, and aortotomy repaired with a 2 x 6 mm PTFE patch. After cross-clamp removal, blood loss was measured and time to hemostasis was recorded. Compared with heparin, IXai resulted in significantly reduce blood loss (6.97 +/- 4.4 g vs 2.72 +/- 2.51 g, respectively, p < 0.008), and time to hemostasis (2.94 +/- 0.77 min vs 2.0 +/- 0.63 min, respectively, p < 0.003). To assess long-term patency and thrombosis, 12 rabbits (given heparin; n = 6 and IXai; n = 6) were observed for up to 2 months post-operatively. No differences were observed between rabbits treated with heparin or IXai; 100% of the grafts were patent with no differences in degree of intimal hyperplasia by histologic analysis. Together, these data suggest that use of IXai in PTFE vascular repair will safely allow realization of the benefits of long-term patency and decreased aneurysmal dilatation, while eliminating the intraoperative morbidity of needle hole bleeding.

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