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Biomedical subjects

U Weber

Publications and source records attributed to U Weber.

At least 145 records · Page 8Linked to original sources
PubMed1990

[The vascularized pedicled flap of superior gluteal artery to hip bone chip--a new concept in the revascularization of hip necrosis in adults].

The development and introduction of microsurgical technique has made possible completely new concept of revascularisation surgery in femoral head necrosis. The bone graft described in this presentation is a pedicled one from the lateral ilium. In five femoral head necrosis a pedicled corticocancellous pelvic graft, supplied by the deep branch of the superior gluteal artery, was transplanted in the femoral head. In all cases it was possible to lift out the pelvic graft from the same side as the affected hip joint. Contrary to the medial iliac bone graft (deep circumflex iliac artery) the lateral iliac bone graft (deep branch of the superior gluteal artery) is inserted into the femoral head dorsally. Preoperatively and postoperatively performed selective angiographies are necessary and presented. In all cases an unimpeded perfusion could be shown three months postoperatively. Advantages and indications of the pedicled bone graft are discussed.

Adult↗
PubMed1990

Three-dimensional determination of an oblique osteotomy in the hip by mathematical optimization fulfilling some anatomical demands.

The present paper describes a nonlinear optimization process to estimate the single cutting plane of an oblique osteotomy in the hip. This kind of osteotomy was introduced and practised by Charit (Research report 81, University of Witwaters brand, Johannesburg, 1981). We calculate the cutting plane in such a way that the postoperative coverage of the resulting two parts of the femur are as great as possible whereby some anatomical constraint conditions are fulfilled. Additionally a simplified preoperative planning is described by using a sphere lying on the femoral head and determined by a least-squares method.

Biomechanical Phenomena↗
PubMed1990

Effect of ethylene glycol on rabbit retinas.

Electrophysiological and histological changes in rabbit retinas were induced by the oral application of ethylene glycol. The electroretinogram revealed a reduced photopic and scotopic activity. Birefringent crystalline deposits were found predominantly in the ganglion cell layer and the inner nuclear cell layer of the retina. These retinal findings were associated with depositions of calcium oxalate crystals in the rabbit kidney and liver.

Administration, Oral↗
PubMed1990

[Recombinant human erythropoietin (rh-EPO) in chronic, dialysis-dependent renal failure: effects on macro- and microcirculation and hematologic parameters].

Recombinant human erythropoietin (rh-EPO) has been shown to be effective in the treatment of renal anemia. Additionally, rh-EPO improves the hemostatic defect of uremia. On the other hand, a hypertensinogen effect and an increased risk for thrombosis have been reported in hemodialysis (HD) patients with rh-EPO. 20 HD patients in Homburg were recruited for a multicenter, placebo-controlled study (MF 3981), aiming to assess the risk of rh-EPO. Initially, 10 patients received rh-EPO at a dose of 3 x 80 U/kg body weight and week which was subsequently adjusted according to the hematocrit. After 6 months, the patients receiving placebo were changed to rh-EPO therapy. Clinical and laboratory data were obtained before, as well as 1, 3, 6 and 12 months after beginning of the study. Erythrocyte counts increased significantly in the rh-EPO group. Also, an increase of platelet count, fibrinogen and plasma viscosity was observed during rh-EPO. Tissue type plasminogen activator and plasminogen activator inhibitor as well as von-Willebrand-factor remained unchanged, although a shortening of the bleeding time was observed. Blood pressure and arterial blood flow were not influenced by rh-EPO.

Blood Viscosity↗
PubMed1989

Lesion and regeneration of the anterior and posterior lens capsule and cortex in rabbits Nd:YAG laser.

With a mode-locked Nd:YAG laser set at various energy levels, anterior and posterior capsular and cortical lesions were produced in the lens of rabbits. Biomicroscopic and Scheimpflug examinations showed the anterior lesion to be healing in a whitish scar that was restricted to the area of the original lesion. Histology and transmission electron microscopy (TEM) demonstrated the proliferation of epithelial cells that produced a new, continuous, basement membrane-like capsule. In the area of the lesion collagenous material, myofibroblast-like cells and macrophages were found. Laser-induced lesions in the posterior lens capsule and lens protein resulted in damage to the capsule and grey opacity of the lenticular proteins, which remained unchanged for 6 weeks. Neither inflammatory nor epithelial cells appeared within the locally damaged lens. Macrophages migrated from the vitreous into the lesion; they were observed either in intercellular clefts or within a lens fibre, almost completely taking up their cross section.

Animals↗
PubMed1989

[The femoral neck pseudarthrosis following medial femoral neck fracture. An indication for the vascularized pedicled iliac crest transplant].

Revascularisation surgery was performed in six cases following medial femoral neck fracture with femoral head necrosis and non-union of the femoral neck. A corticospongiosis pelvic graft supplied by the deep circumflex iliac artery was implanted as an autologous heterotopic pedicled transplant. The operative procedure was the same in all cases, since it was possible to lift out the pelvic graft from the same side as the affected hip joint, thus making a microvascular anastomosis unnecessary. Follow-up examination after 15-27 months revealed that, in all cases, osseous consolidation of the pseudarthrosis had been achieved and that further segmental collapse of the contour of the femoral head had been prevented. The angiographic studies performed during the examination demonstrated unimpeded circulation in the pedicle of the transplants in five of the six cases, as long as 3 months after the operation. For the first time it was possible in these five cases, by means of a transplant angiograph, to demonstrate integration of the graft into the biologically weak post-traumatic transplant region.

Bone Transplantation↗
PubMed1989

[Liposomes--drug carriers for retinally active drugs?].

Small lipid droplets, the so-called liposomes, can serve as drug carriers and can in theory be targeted directly at diseased tissue. Thus, comparatively smaller quantities of drugs than usual are necessary. However, liposomes are recognized by the immune system and are absorbed by the reticuloendothelial system and therefore also by the Kupffer cells in the liver. These cells are storage compartments for esterified vitamin A. As about 80% of the liposomes are metabolized in the liver, retinoids form a pool for substances transported with retinoid-binding proteins. Whether retinoids reach the retina via direct liposome contact or through the endocytotic process is still not clear. In rabbits, however, retinoids applied in small unilamellar liposomes (SUV) produce photoreceptor malfunctioning (isotretinoin and etretinate) and photoreceptor outer segment damage with an increase in phagocytotic activity of the retinal pigment epithelium (etretinate).

Drug Carriers↗
PubMed1988

A specific method for the direct determination of lipoprotein cholesterol in electrophoretic patterns.

Lipoproteins are separated electrophoretically and cholesterol is visualised with an enzymic reagent specific for cholesterol in which the gels are incubated. Quantitation of the individual fractions is accomplished by scanning densitometry. No sample pretreatment is necessary. All major fractions are detected readily. Accuracy agrees favorably with results from the ultracentrifugation. On the average, imprecision is 3.1% for beta-, 6.9% for prebeta-, and 5.2% for alpha-lipoprotein cholesterol. Concentration and color development are linear up to 8 mmol/l cholesterol in a given lipoprotein fraction. The results of the direct enzymic procedure for beta-, prebeta- and alpha-lipoprotein cholesterol are compared to the quantitative lipoprotein electrophoresis after precipitation with phosphotungstic acid and bivalent cations.

Cholesterol↗
PubMed1988

Characterization of the protein which binds insulin-like growth factor in human serum.

The binding of the 125I-labelled insulin-like growth factors I and II (125I-IGF I and 125I-IGF II) to the high-molecular-mass binding protein of human serum was characterized. With diluted human serum both growth factors showed optimal specific binding at 4 degrees C and pH 5-6. When 0.1% Triton X-100 was present in the incubation buffer an increase in the affinity of the IGF-binding protein was induced, which produced an enhanced binding of IGF I and IGF II. Competition experiments with various peptide hormones revealed that the native IGF-binding protein complex binds both the IGF I and IGF II with high specificity. Analysis of binding data according to the method of Scatchard resulted in linear plots for IGF I and IGF II respectively, indicating that in human serum only a single class of non-interacting binding sites is present. At optimal binding conditions the dissociation constants were determined to be 0.28 x 10(-9) M for IGF I binding and 0.66 x 10(-9) M for IGF II. Human serum was gel-filtered on Sepharose CL-6B at neutral pH and the eluate was assayed for binding activity with both IGF I and IGF II. One peak with an apparent molecular mass of 175 kDa and a Stokes radius of 4.8 nm was determined for both growth factors. Thus, our data suggest that human serum contains one class of high-molecular-mass binding protein with comparable binding characteristics for IGF I and IGF II.

Binding Sites↗
PubMed1988

[Electroretinography in AIDS retinopathy and AIDS cytomegalovirus retinitis with ganciclovir therapy].

Electroretinographic (ERG) investigations were performed in three AIDS patients. The first had cotton wool-like spots in both eyes (AIDS "retinopathy"). The second presented with the same changes in his right eye and an acute cytomegalovirus (CMV) in his left eye. In the third patient signs of healed peripheral retinochoroiditis were found. In CMV retinitis the retinal damage demonstrated by ERG correlated well with the ophthalmoscopic findings. As the ERG improved concurrently with Ganciclovir therapy, retinal function can be monitored by means of ERG controls. In the cases of AIDS "retinopathy" with only a few cotton wool-like spots and with healed peripheral retinochoroiditis, pronounced changes in the ERG were seen regularly; these were most probably caused by ischemia of the inner retinal layers.

Acquired Immunodeficiency Syndrome↗
PubMed1988

[Disorders of retinal function in long-term therapy with retinoid etretinate].

Four patients receiving etretinate as long-term therapy were examined. The accumulated dosage was 135 g for Patient 1, about 80 g for Patients 2 and 3, and 31 g etretinate and 4.8 g etretine (Ro 10-1670; main metabolite of etretinate) for Patient 4. Clinical examinations, visual fields (Haitz, Amsler, Goldmann), and EOGs (two patients) were normal. Patient 1 (135 g) showed a decreased level of rod sensitivity at dark adaptation (Goldmann-Weekers), whereas the cone responses were regular in all cases. Furthermore, Patient 1 showed reduced scotopic ERG amplitudes. Aside from this, photopic and scotopic ERGs were normal as far as a- and b-wave amplitudes and peak latencies were concerned. The flicker fusion frequencies were found to be regular. The peak latencies of the R2-component of the early receptor potentials seemed rather short. In all four patients alterations of color sense were analyzed in the Farnsworth Munsell 100 Hue test. The color sense defect seems to originate in the blue-yellow spectrum and--at higher dosages--extends to the red-green spectrum. Examinations with the anomaloscope revealed deuteranomalous settings. Ophthalmological checks for patients receiving long-term aromatic retinoid therapy are recommended, especially with regard to dark adaptation and color sense.

Adult↗
PubMed1988

Nitrendipine in patients with end-stage renal disease and hypertension.

Calcium antagonists reduce the calcium uptake in vascular cells. The reduction of intracellular calcium leads to vasodilatation and lowering of the blood pressure. The cardiac output is increased, for example, by nitrendipine and related agents, so that the supply of blood to essential organs is improved. Despite the blood pressure decrease, the plasma renin activity increases only slightly and the plasma aldosterone concentration not at all after administration of nitrendipine. The effects of nitrendipine were examined in a study carried out over a period of 6 months on 10 patients suffering from renal hypertension and end-stage renal disease requiring compulsory dialysis. In all patients, adequate blood pressure control was achieved with, in some cases, low doses of nitrendipine combined with other antihypertensive medication. Nitrendipine was very well tolerated, and no side effects were observed.

Adult↗
PubMed1988

[Treatment and results in severe craniocerebral trauma].

Treatment of severe craniocerebral traumas in medium and major hospitals not provided with special neurosurgical equipment requires particularly close interdisciplinary cooperation between surgeons, neurologists and anaesthesiologists. CT facilities are an essential prerequisite for best possible patient care. Patient safety during the posttraumatic and postoperative phases is improved by measuring the intracranial pressure. Whereas corticosteroid treatment may be arguable, barbiturate treatment should presently not be a routine procedure because of its side effects and high rate of complications.

Brain Concussion↗
PubMed1988

[Classification, clinical aspects and diagnostic pathology of soft tissue tumors].

Soft tissue tumors often present a clinical problem, and their histology is heterogeneous. It is only in the last 15 years that an internationally accepted classification has been widely used to assess prognosis and determine therapy. In the present article the important clinical aspects of treatment are presented in combination with new therapeutic and diagnostic discoveries. Immunohistochemistry is now more widely used as an accepted diagnostic method than electron microscopy.

Biomarkers, Tumor↗