Severity of organ injury as a predictor of acute mortality for disparate patterns of absorbed dose distribution.

Nonuniform distribution of absorbed dose is frequently encountered in the irradiated mammal; the degree of nonuniform distribution is generally more severe as the size of the animal increases and the energy or penetrating power of the radiation decreases. However, acute mortality under these conditions, e.g., from the hematopoietic syndrome, appears not to be consistently predictable from the dose at any given location or locations within the animal. It is thus reasonable to seek a biological quantity that may be adequate for this purpose. Accordingly, it was postulated that, in animals dying from the bone marrow syndrome, survival is determined by the total number of viable stem cells remaining in the entire body, independent of their distribution. To test this hypothesis, the LD50/30 value for mice exposed to nonuniform irradiation of varying degrees of severity was obtained, as was that for mice receiving uniform total-body irradiation. The distribution of bone marrow in transverse segments of tissue along the spinal axis was determined, as was the dose to each of the segments. The data were analyzed by multiplying, for each segment, the fraction of stem cells in the fraction of cells surviving, as determined from the dose and a survival curve for stem cells determined separately. The sum of these products yielded the surviving number of stem cells in the total mouse, for both the uniformly and nonuniformly exposed animals. The surviving fraction was found to differ by no more than 20%; this was taken to be reasonable evidence that, based on the number of surviving stem cells, it is possible to predict the mortality rate for both uniform and markedly nonuniform irradiation.

[Possibilities and limits of interventional therapy in chronic peripheral arterial occlusive disease]. / Möglichkeiten und Grenzen der Interventionellen Therapie bei der chronischen peripheren arteriellen Verschlusskrankheit.

In the therapy of the chronic peripheral vascular occlusion, angioplasty is rarely used to treat the infra-renal aortic stenosis, whereas the stenosis and the short occlusion of the iliac artery is a classical indication. Primarily, stenoses and occlusions of the iliac artery should be treated with balloon angioplasty exclusively. Only secondarily, when the result of angioplasty was insufficient, e.g. remaining stenosis or dissection, stent implantation is appropriate. Angioplasty is most frequently applied in the obliteration of the femoro-popliteal artery. It can be stated that early- and long-term results are the better, the shorter the occlusion is. Stent implantation in the femoro-popliteal artery should be avoided because of poor results. Only with the intention of limb salvage, when there is no opportunity for surgical treatment, a stent implantation should be considered. In case of recurrent stenoses after stent implantation, angioplasty can be reapplied with great success. The indication for any vascular intervention should be a decision of both, the interventional radiologist and the vascular surgeon, because both kinds of treatment are palliative and not causal. It is the task of the angiologist to do clinical diagnostics and the after-treatment. Quality monitoring is indispensable. It consists of documentation of pre-angioplasty diagnostics and should be able to prove the correct indication for the intervention. The result of the intervention should also be documented by angiography and functional tests. Regular control of the patient after the intervention is necessary for the early recognition of recurrent stenoses.

[Progress in arterial reconstruction of the upper and lower leg--percutaneous transluminal procedures]. / Fortschritte arterieller Rekonstruktion an Ober- und Unterschenkel--Perkutane transluminale Verfahren.

Conventional PTA represents the state of the art method for treating arterial occlusive disease of the leg arteries. Rotational angioplasty is an improvement over conventional PTA in treating long proximal occlusions of the SFA. It can also be used as a second treatment in cases that were primarily unsuccessful with PTA, with an initial success of 59%. Stent implantation is mainly indicated in limb-threatening ischemia. It also permits successful management of an aneurysm as a late and rare complication correlated to PTA. Atherectomy produces better initial success in eccentric stenotic lesions than PTA. It also permits the successful management of obstructive intimal flaps after angioplasty. The new techniques only improve on PTA, if they are used in the differential therapeutic strategy mentioned above.