The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles.

The purpose of this work is a detailed comparison of the fundamental magnetic properties of nanocomposite systems consisting of Fe3O4 nanoparticle-loaded porous silicon as well as silicon nanotubes. Such composite structures are of potential merit in the area of magnetically guided drug delivery. For magnetic systems to be utilized in biomedical applications, there are certain magnetic properties that must be fulfilled. Therefore magnetic properties of embedded Fe3O4-nanoparticles in these nanostructured silicon host matrices, porous silicon and silicon nanotubes, are investigated. Temperature-dependent magnetic investigations have been carried out for four types of iron oxide particle sizes (4, 5, 8 and 10 nm). The silicon host, in interplay with the iron oxide nanoparticle size, plays a sensitive role. It is shown that Fe3O4 loaded porous silicon and SiNTs differ significantly in their magnetic behavior, especially the transition between superparamagnetic behavior and blocked state, due to host morphology-dependent magnetic interactions. Importantly, it is found that all investigated samples meet the magnetic precondition of possible biomedical applications of exhibiting a negligible magnetic remanence at room temperature.

Magnetically interacting low dimensional Ni-nanostructures within porous silicon.

Electrodeposition of ferromagnetic metals, a common method to fabricate magnetic nanostructures, is used for the incorporation of Ni structures into the pores of porous silicon templates. The porous silicon is fabricated in various morphologies with average pore-diameters between 40 and 95 nm and concomitant pore-distances between 60 and 40 nm. The metal nanostructures are deposited with different geometries as spheres, ellipsoids or wires influenced by the deposition process parameters. Furthermore small Ni-particles with diameters between 3 and 6 nm can be deposited on the walls of the porous silicon template forming a metal tube. Analysis of this tube-like arrangement by transmission electron microscopy (TEM) shows that the distribution of the Ni-particles is quite narrow, which means that the distance between the particles is smaller than 10 nm. Such a close arrangement of the Ni-particles assures magnetic interactions between them. Due to their size these small Ni-particles are superparamagnetic but dipolar coupling between them results in a ferromagnetic behavior of the whole system. Thus a semiconducting/ferromagnetic hybrid material with a broad range of magnetic properties can be fabricated. Furthermore this composite is an interesting candidate for silicon based applications and the compatibility with today's process technology.

Investigation of a Mesoporous Silicon Based Ferromagnetic Nanocomposite.

A semiconductor/metal nanocomposite is composed of a porosified silicon wafer and embedded ferromagnetic nanostructures. The obtained hybrid system possesses the electronic properties of silicon together with the magnetic properties of the incorporated ferromagnetic metal. On the one hand, a transition metal is electrochemically deposited from a metal salt solution into the nanostructured silicon skeleton, on the other hand magnetic particles of a few nanometres in size, fabricated in solution, are incorporated by immersion. The electrochemically deposited nanostructures can be tuned in size, shape and their spatial distribution by the process parameters, and thus specimens with desired ferromagnetic properties can be fabricated. Using magnetite nanoparticles for infiltration into porous silicon is of interest not only because of the magnetic properties of the composite material due to the possible modification of the ferromagnetic/superparamagnetic transition but also because of the biocompatibility of the system caused by the low toxicity of both materials. Thus, it is a promising candidate for biomedical applications as drug delivery or biomedical targeting.

Synthesis and Magnetic Characterization of Metal-filled Double-sided Porous Silicon Samples.

A magnetic semiconductor/metal nanocomposite with a nanostructured silicon wafer as base material and incorporated metallic nanostructures (Ni, Co, NiCo) is fabricated in two electrochemical steps. First, the silicon template is anodized in an HF-electrolyte to obtain a porous structure with oriented pores grown perpendicular to the surface. This etching procedure is carried out either in forming a sample with a single porous layer on one side or in producing a double-sided specimen with a porous layer on each side. Second, this matrix is used for deposition of transition metals as Ni, Co or an alloy of these. The achieved hybrid material with incorporated Ni- and Co-nanostructures within one sample is investigated magnetically. The obtained results are compared with the ones gained from samples containing a single metal.

Haemodialysis-membrane biocompatibility and mortality of patients with dialysis-dependent acute renal failure: a prospective randomised multicentre trial. International Multicentre Study Group.

BACKGROUND: There is controversy as to whether haemodialysis-membrane biocompatibility (ie, the potential to activate complement and neutrophils) influences mortality of patients with acute renal failure. We did a prospective randomised multicentre trial in patients with dialysis-dependent acute renal failure treated with two different types of low-flux membrane. METHODS: 180 patients with acute renal failure were randomly assigned bioincompatible Cuprophan (n=90) or polymethyl-methacrylate (n=90) membranes. The main outcome was survival 14 days after the end of therapy (treatment success). Odds ratios for survival were calculated and the two groups were compared by Fisher's exact test. Analyses were based on patients treated according to protocol (76 Cuprophan, 84 polymethyl methacrylate). FINDINGS: At the start of dialysis, the groups did not differ significantly in age, sex, severity of illness (as calculated by APACHE II scores), prevalence of oliguria, or biochemical measures of acute renal failure. 44 patients (58% [95% CI 46-69]) assigned Cuprophan membranes and 50 patients (60% [48-70]) assigned polymethyl-methacrylate membranes survived. The odds ratio for treatment failure on Cuprophan compared with polymethyl-methacrylate membranes was 1.07 (0.54-2.11; p=0.87). No difference between Cuprophan and polymethyl-methacrylate membranes was detected when the analysis was adjusted for age and APACHE II score. 18 patients in the Cuprophan group and 20 in the polymethyl-methacrylate group had clinical complications of therapy (mainly hypotension). INTERPRETATION: There were no differences in outcome for patients with dialysis-dependent acute renal failure between those treated with Cuprophan membranes and those treated with polymethyl-methacrylate membranes.

[Intraabdominal cystic lymphangioma in childhood. Report of 2 cases]. / Intraabdominelles zystisches Lymphangiom im Kindesalter. Zwei Falldarstellungen.

Intraabdominal cystic lymphangiomas are rare tumor-like lesions, predominantly found in the pediatric age group, but also in juveniles or young adults. Lymphangiomas are always benign and do not recur after complete excision. In this paper we report on two 4-year old children with a history of abdominal discomfort due to large cystic lymphangiomas, the diagnostic procedure and the definite surgical therapy by complete excision. While the histogenesis of cystic lymphangiomas is generally discussed controversely, in one of our cases there is some evidence that the lesion developed in fetal lifetime in combination with a scar of the intestinal wall of the ileum.

Combination chemotherapy with CHOP for recurrent thrombotic thrombocytopenic purpura.

We report the case of a 42-year-old woman with chronic recurrent thrombotic thrombocytopenic purpura. Therapy with corticosteroids, high-dose immunoglobulins, plasma exchange and cyclophosphamide only induced short-lasting remissions during a course of almost 3 months. Following a severe relapse on day 90 after the start of symptoms, polychemotherapy with cyclophosphamide. adriamycin, vincristine and prednisolone (CHOP) was begun. After two cycles of CHOP the patient has stayed in complete remission, with normal platelet counts for more than 9 months to date.

Advantages of isovolemic large-volume erythrocytapheresis as a rapidly effective and long-lasting treatment modality for red blood cell depletion in patients with polycythemia vera.

Long-term survival of patients with polycythemia vera (PV) is essentially determined by the ability to reduce the risk of thromboembolic complications resulting from the altered rheological conditions by the high red blood cell (RBC) mass of these patients. RBC depletion to normal hematocrit (Hct) values is the first line therapy and should be preferred to chemotherapy (or P32) because of the long-term risk of acute leukemia or other secondary malignancies. RBC depletion is accomplished much more effectively and rapidly by erythrocytapheresis (EA) than by repeated phlebotomies and has been shown to be well tolerated and accepted by the patients (8). The main indications for EA for a PV patient (often newly diagnosed) are high risk Hct values of >55-60% that can be reduced to the normal range within 1-2 h. The long-lasting effect (median interval between 2 EA treatments: ca. 6 months) is partially the result of the massive loss of iron, a growth factor for erythropoesis. This has been shown by in vitro studies in erythroid progenitor cells of PV patients before and after EA (11). The advantages and possible disadvantages of EA treatment are discussed.

Specificity of circulating and tissue-bound autoantibodies in Goodpasture syndrome.

Goodpasture syndrome is an often fatal autoimmune disease associated with glomerulonephritis and/or pulmonary hemorrhage. The clinical manifestations of this disease correlate well with the presence of circulating antiglomerular basement membrane (GBM) autoantibodies. The primary target antigen in glomerular and alveolar basement membranes is thought to be the alpha 3 chain of type IV collagen. Nearly all that is known about anti-GBM antibodies in humans comes from work on unbound circulating antibody. We recently had the unique and rare opportunity to obtain early postmortem antibody and tissues from a patient who died with catastrophic Goodpasture syndrome. The specificity of circulating, kidney-bound and lung-bound autoantibodies from this patient was evaluated against a variety of purified basement membrane constituents. The results indicate that the primary target for the circulating and tissue-bound autoantibodies is the NC1 domain of the alpha 3(IV) chain of type IV collagen. Additionally, all the antibodies recognize a cryptic epitope/s on the alpha 3(IV)NC1 hexamer. Furthermore, tissue-bound and circulating antibodies compete with one another for overlapping epitopes on the antigen. These findings demonstrate that circulating autoantibodies in Goodpasture syndrome are highly representative of those bound to organ tissues, strengthening the notion that pathogenic autoantibodies are targeted to the alpha 3(IV)NC1 collagen, and that previous reports of findings in the circulation may be applicable to tissue injury.

[Technical possibilities for preventing insufficiency of pancreaticojejunostomy anastomosis]. / Technische Möglichkeiten zur Verhinderung der Insuffizienz einer Pankreo-Jejunostomie-Anastomose.

Today, insufficiency of pancreatic anastomosis is a rare complication following pancreatic head resection. Thirty years ago, insufficiency rates and mortality after Kausch-Whipples operations were from 30% to 52%. What makes pancreatic anastomosis certain today? 1. An end-to-side technique in telescopic manner should be preferred. 2. Pancreogastric anastomosis is also possible. 3. Fibrin occlusion of the pancreatic duct system would be helpful. 4. Simultaneous decrease in pancreatic secretion by octreotide seems to be a well-proven help in avoiding pancreatic anastomosis failure.

[Change in renin activity and blood pressure in the dog autologous kidney transplant model with modified HTK solution]. / Veränderung der Reninaktivität und des Blutdruckverhaltens im autologen Nierentransplantationsmodell am Hund bei Modifikation der HTK-Lösung.

Investigations of changes in activity of renin and blood pressure after reperfusion of the kidney transplant using HTK solution were carried out by means of an autologous, heterotopic model of kidney transplantation applied to dogs. Duration of cold ischemia was 48 h. According to variations in the composition of the HTK perfusion solution three test groups were set up. During the first 20 min after recirculation in each test group the renal venous and arterial renin activities were measured. Parallel to renin activity, the arterial blood pressure was recorded. During the first few minutes following recirculation of the kidney transplant the renin levels in the venous blood of the kidney were higher in test group 1 (HTK solution, perfusion height 120 cm) than in either of the other two, showing a median maximal increase of 195 ng/ml.h. In test group 2 the maximal venous renin concentration fell to 145 ng/ml.h, while graphs take a more uniform course. Test group 3 (HTK/tryptophan) differed from the others in having further improved renin values. After the 7.5 min of observation normal venous renin concentrations were measured following earlier values for maximal increase between 23.1 ng/ml.h and 120 ng/ml.h (median 61.5 ng/ml.h). The best reperfusion of the kidney was observed in the tryptophan group, albeit without any recognizable positive effects on the other renal functions. Initially low renin values do not necessarily correlate with a smooth postoperative renal function and vice versa. Initial renin values cannot provide a secure basis for predicting instant as well as long-term postoperative functions.(ABSTRACT TRUNCATED AT 250 WORDS)

[Early and late outcome of gastrectomy de principe]. / Früh- und Spätergebnisse der Gastrektomie de principe.

Presented is a survey of 10 years experience of "Gastrectomie de principe" in the treatment of gastric cancer performed in the Surgical Department of Fulda. 219 gastrectomies were analysed, all of which were combined with lymphadenectomy of compartment I and II. Splenectomy was performed in 91%. 20% of the patients were operated with an early cancer, 37% showed no lymph node involvement. The rate of complications due to surgery was 13%, in 5.5% of patients we saw an insufficiency of the anastomosis, causing lethal outcome in 40% of these cases. The overall hospital mortality was 5.5%. Survival rates depended strongly on lymph-node involvement. The highest 5-year-survival of nearly 90% was seen in patients with an intestinal carcinoma in tumor stage T1 N0 M0, the 5-year-survival of all patients with an early cancer was 82%. The overall 5-year-survival was 25%. Total gastrectomy as the standard operative procedure shows low mortality, good controllability of complications and is to be recommended as a sufficiently safe therapeutical concept in patients with gastric cancer.