Normal Flow Parameters Research Articles

Lymphangiogenesis following obstruction of large postnodal lymphatics in sheep

We examined the impact of lymph flow obstruction in large post-nodal lymphatic vessels in sheep. A silk ligature was placed 2 cm downstream from the prescapular or popliteal lymph node and tightened to interrupt flow. At 6, 12 and 16 weeks after lymph flow blockage, a network of small interconnecting lymphatics (∼ 10–40 μm in diameter) could be observed in the vicinity of the ligature. These were identified using antibodies to the lymphatic endothelial markers LYVE-1 or VEGFR-3 or unequivocally, with the upstream intraluminal injection of the non-specific cell dye CFDA-SE. The observed lymphangiogenesis coincided with increased levels of Prox1, Tie2 (Y992) phosphorylation, MAPK activation, and decreased Akt activition. In the popliteal preparations, saline was infused into the prenodal ducts upstream of the regeneration site. The slopes of the inflow pressure versus flow relationships were 17.3 ± 3.6, immediately after vessel obstruction, 36.2 ± 9.6 at 6 weeks and 15.0 ± 5.3 at 12–16 weeks. For comparison, the average slope in a completely intact popliteal system was 3.1 ± 0.3 (from a previous publication). The resistance to flow remained high up to 12–16 weeks after flow obstruction suggesting that normal flow parameters had not been achieved over this time. The lymph node appeared to have some role in limiting the impact of post-nodal lymph obstruction, a function that appeared to be compromised by lymph stasis.

Arteriovenous intracavernous post-traumatic fistula: clinical management and treatment by superselective embolization

Arteriovenous intracavernous post-traumatic fistula (FAV) is a rare post-traumatic lesion for which the first choice of treatment is superselective embolization. We present a case of post-traumatic fistula in a 45-year-old patient. The patient underwent penile blood gas analysis and color Doppler ultrasonography and was treated with superselective embolization with an acrylic co-polymer. Postoperative arteriography showed obliteration of the fistula. Color Doppler ultrasonography 60 days after the procedure showed reacquired physiologic patency of the cavernous artery with normal flow parameters. The results of this case confirm superselective embolization as the reference standard treatment of FAV. We propose the use of an acrylic co-polymer as a new, effective embolizing medium.

Effect of Flow Pulsations on Form Drag

Relatively simple theoretical procedures enable the pressure loss of the simpler forms of baffle used for flame stabilisation in combustion chambers to be computed, while tests made under non-burning conditions are available for ad hoc testing of the geometrically more complicated forms. Both these methods, with the appropriate corrections for the momentum changes due to burning, have in the past proved suitable for the prediction of the drag of aero-engine combustion chambers under operating conditions. Recently, however, it has been found that under certain conditions, associated especially with very high rates of heat release, the drag of combustion systems can become very much greater than would be predicted either from simple theoretical considerations or from conventional “cold” tests, and vary in an unexpected manner with the normal flow parameters.