Spatial variation of au coverage as the driving force for nanoscopic pattern formation.

Au induced faceting of a 4 degrees vicinal Si(001) surface was studied with chemical resolution using soft x-ray photoemission electron microscopy. For the first time a direct and quantitative determination of the local Au coverage in situ and during deposition was possible. Au atoms, necessary for the expansion of (001) terraces, are accummulated from a lattice gas, resulting in a phase separation between Au enriched terraces and Au depleted step bunches. During a second stage Au also adsorbs on the step bunches and transforms them into (119) facets. A simple Monte Carlo simulation shows that the initial coverage difference between terraces and bunches determines the regularity of the formed mesoscopic grating.

Sympathetic neuronal activity in diabetic and non-diabetic subjects with peripheral arterial occlusive disease.

Despite the vasoconstrictory influence of the alpha-adrenergic system on the peripheral blood circulation the results of the sympathectomy were not satisfying in the therapy of peripheral arterial occlusive disease (PAOD). The aim of the present investigation was to clarify the pathophysiologic mechanisms of this clinical observation. Free and sulfoconjugated catecholamines were determined in the femoral artery, vein, and cubital vein of 19 healthy controls, 21 non-diabetic patients with PAOD stage II, 8 non-diabetic (PAOD IV) and 20 diabetic patients (D IV) with PAOD stage IV. In comparison with controls and group PAOD II an increased sympathoneuronal tone in group PAOD IV was evident at rest. Sympathetic activation was not restricted to the affected limb, since femoral and cubital venous norepinephrine levels were not different and plasma epinephrine fractional extraction (PEFE) was not altered by angiopathy. The lower sympathoneuronal activation in the group D IV may be attributed to an impaired pain perception or a reduced dopamine beta-hydroxylase activity indicated by a lower ratio of norepinephrine to dopamine. The failing long-term efficacy of lumbar sympathectomy in critical arterial limb disease may be explained by marked spontaneous sympathicolysis in diabetics, whereas in non-diabetics with sympathetic activation other mechanisms like development of unilateral Mönckeberg sclerosis, progression of proximal arterial occlusion or induction of steal effects have to be discussed.

[Primary right atrial leiomyosarcoma in an adult]. / Primäres rechtsatriales Leiomyosarkom bei einem Erwachsenen.

Primary leiomyosarcoma of the heart is very rare, and in most cases the diagnosis is performed during postmortem examinations. We report on a 71-year-old woman with a large leiomyosarcoma of the right atrium. The preoperative diagnosis of cardiac tumor was made by 2-D echocardiography, transesophageal echocardiography, computed tomography, and MR-imaging, and was confirmed by histological and immunhistological findings of the resected part.

Pharmacokinetics of mezlocillin after intraarterial or intravenous injection in patients with peripheral arterial occlusive disease (PAOD).

In the first part of this study, which was already published in this journal, tissue- and serum concentrations of Mezlocillin were compared one hour after a single dose of 2 g injected either intraarterially or intravenously in patients with ischemic lesions, due to PAOD or moist diabetic gangrene. In nearly all tissues of the minor perfused metatarsus and in the thigh, estimated as being physiologically perfused, there was an impressive trend to higher concentrations after i.a. injection. The concentrations in the thigh were higher than in the metatarsus after both, i.a. or i.v. injection. In this second part, tissue concentrations are compared three to four hours after the end of i.a. or i.v. injection of the same dose. After this interval of time, there is no longer any striking difference between the tissue concentrations after i.a. compared to i.v. injection within the physiologically perfused thigh, the concentrations in the reduced perfused metatarsus still show a convincing tendency to higher values after i.a. injection. It is concluded, that the initial tissue concentration of an antibiotic depends on its concentration within the inflowing blood and on the amount of the blood perfusion. The decline of the tissue concentration time course is more pronounced after i.a. injection. The advantage of higher concentrations after i.a. injection is limited to the initial phase after the injection.

Assessment of muscular metabolism in peripheral arterial occlusive disease using 31P nuclear magnetic resonance spectroscopy. Comparison with metabolite concentrations in femoral blood.

The behaviour of muscular metabolism was investigated in 10 patients with peripheral arterial occlusive disease stage II at rest and after maximum ergometric calf exercise. The intracellular concentrations of phosphocreatine, inorganic phosphate and adenosine triphosphate as well as muscle pH were measured by means of 31P magnetic resonance spectroscopy and compared with those from a control group. In addition, arteriovenous differences in concentrations of lactate, pyruvate, ammonia, hypoxanthine and alanine in the femoral blood were determined. The fall in intracellular phosphocreatine concentration during exercise was significantly greater in the calf muscles of patients with arterial occlusion than in controls and correlated linearly with the increase in femoral arteriovenous differences in lactate, ammonia and alanine. A significant fall in intracellular pH occurred during muscular activity only in the patient group, but not in the identically exercised control group. The fall in pH correlated closely with the rise in arteriovenous lactate difference in the femoral blood. The intramuscular ATP concentration remained constant throughout the exercise procedure. The behaviour of both the directly and indirectly measured metabolites permits the deduction of activation of the creatine kinase reaction, glycolysis, myokinase reaction and the purine nucleotide cycle during exercise-induced hypoxia in the presence of arterial occlusive disease. The anaerobic production of energy is sufficient to maintain the ATP concentration even during claudication pain.(ABSTRACT TRUNCATED AT 250 WORDS)

[Regulation of ischemic muscle metabolism in peripheral arterial occlusive disease]. / Regulation des ischämischen Muskelstoffwechsels bei peripherer arterieller Verschlusskrankheit.

A review of metabolic pathways is presented, which are involved in muscular energy production during hypoxia according to recent experimental findings. By means of own exercise examinations the course of reactions providing ATP anaerobically in the muscles of limbs with poor circulation is analysed. Therefore, the arteriovenous differences in the concentrations of lactate, pyruvate, ammonia, hypoxanthine and alanine in the femoral blood of patients with stage II AOD were determined. In addition, the intracellular phosphorus compounds ATP, PCr and Pi as well as the tissue pH were measured noninvasively in the calf muscles using 31P magnetic resonance spectroscopy. The results give evidence for marked activation of the creatine kinase reaction, of glycolysis, of the myokinase reaction and of the purine nucleotide cycle in the ischaemic musculature at loads of short duration, which are in total sufficient to maintain the concentration of ATP even during claudication pain. In spite of salvage pathways like alanine formation, the end products of these "emergency reactions", Pi, H+ and NH4+, accumulate and exert deleterious cytotoxic effects, which are thought to be responsible for rapid muscle fatigue and claudication pain in PAOD.