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Biomedical subjects

M Schrader

Publications and source records attributed to M Schrader.

At least 109 records · Page 6Linked to original sources
PubMed1996

Interaction of microtubules with peroxisomes. Tubular and spherical peroxisomes in HepG2 cells and their alterations induced by microtubule-active drugs.

We have studied the interaction of microtubules with peroxisomes and the influence of changes in the microtubular network on the peroxisomal compartment. From the several cell lines analyzed for this purpose, HepG2 cells proved to be the best candidate exhibiting both a well-developed cytoskeleton and a peroxisomal compartment with great plasticity. Three distinct types of peroxisomes: small spherical (0.1-0.3 micron), rod-shaped (0.5 micron) and elongated tubular (up to 5 microns) ones were identified in this cell line. A shift of the elongated tubular forms to spherical particles was noted by increasing the density of cells in culture, whereas no correlation between the distinct peroxisomal forms and the cellular proliferation could be observed. At time points when the elongated tubular peroxisomes were disappearing, many spherical peroxisomes arranged like 'chains of beads on a string' were observed, suggesting that the fission of elongated tubular forms may give rise to newly developing spherical peroxisomes. A clear association of spherical peroxisomes with microtubules was visualized by double immunofluorescence in combination with confocal laser scanning microscopy (CLSM). Treatment with a variety of microtubule-depolymerizing drugs (colcemid, nocodazole, vinblastine) induced a significant increase in the frequency of tubular peroxisomes and led to the formation of peroxisomal clusters. These effects were reversible since already 1 to 2 h after removal of the drugs from the culture medium, a uniform distribution of spherical peroxisomes was reestablished. Taxol, a microtubule-stabilizing drug, on the other hand exerted no significant effects on the peroxisomal compartment. The direct interaction of microtubules with peroxisomes in vitro was demonstrated using highly purified rat liver peroxisomes and taxol-stabilized microtubules from bovine or pig brain. The binding of peroxisomes to microtubules was visualized by video-enhanced contrast microscopy (VECM) and was abolished by pretreatment of peroxisomes with 100 mM KCl ('stripping'), proteinase K or trypsin. Incubation with cytosol restored the binding capacity of KCl-treated peroxisomes, but did not complement the protease treatment. The data presented provide for the first time evidence for a direct interaction of microtubules with the peroxisomal compartment indicating that this cytoskeletal system plays an important role in the morphogenesis and intracellular distribution of peroxisomes.

Actin Cytoskeleton↗
PubMed1995

Tragal cartilage in the primary reconstruction of defects resulting from a nasal septal abscess.

Immediate reconstruction of nasal septal sequestration following a septal abscess with autologous tragal cartilage graft is the method of choice in children and adolescents. On one hand autologous tissue is used, thus foreign body reaction with rejection or irregular resorption does not occur. On the other hand further defects in the posterior septal segment with additional damage to growth zones do not arise. Furthermore local tissue is saved, thus it will be available later, in case revision surgery will be necessary. But in contrast to costal cartilage tragal cartilage is easy to obtain in reconstruction of the nasal septum. No visible or functional defect arise at the donor site.

Abscess↗
PubMed1995

[Lightening strike injuries of the ear].

Although lightning injuries are quite common, lightning-induced damage to the middle or inner ear and to the vestibular nerve has been reported in only a very few cases. Two case reports are presented: a 22-year-old woman and a 26-year-old man who experienced lightning injuries to several body parts including the ear. Pathophysiology, diagnostic criteria and treatment are discussed.

Adult↗
PubMed1995

[Reliability of magnetic stimulation in the diagnosis of peripheral facial paralysis of idiopathic origin].

To evaluate the transcranial magnetic stimulation in the early diagnosis of traumatic facial palsy 7 patients with an incomplete Bell's palsy were examined. The clinical examination, electric stimulation and magnetic stimulation were performed daily from the 2nd day until the 6th day, at the 12th day and three months after onset of the disease. The mean latency of the surface potential of the orbicularis oculi muscle after electrical stimulation was 2.7 msec. On the healthy side the answer following transcranial ipsilateral cisternal magnetic stimulation was detectable after 6.8 msec. From the beginning no response could be recorded on the affected side. After clinical restitution of the Bell's palsy after three months there was still no response. On the other hand, the controlateral, cortical transcranial magnetic stimulation was not significantly reduced. In conclusion, the cisternal transcranial magnetic stimulation gives no further information beyond the clinical examination. The cisternal stimulation is useful, if a clinical examination is impossible e.g. in an unconscious patient after head injury.

Adolescent↗
PubMed1995

[Diagnostic and therapeutic problems of dacryocystolithiasis].

An uncommon case of a woman with dacryocystolithiasis is reported with results of mineralogical investigation of the stone removed. This stone was found to consist of tricalcium phosphate following its removal by dacryocystorhinostomy. At present dacryocystolithiasis is one of the differential diagnoses of malignant tumors of the paranasal sinuses and lacrimal excretory system.

Adult↗
PubMed1995

Effects of fixation on the preservation of peroxisomal structures for immunofluorescence studies using HepG2 cells as a model system.

The immunofluorescence technique has become an important tool for the investigation of peroxisomes in cell culture. We have used this method for the study of peroxisomes in the human hepatoblastoma cell line HepG2. A marked heterogeneity of peroxisomal forms was detected. Besides spherical (about 100 nm) and rod-shaped structures (about 300 nm) many elongated, undulating tubular forms (up to 5 microns) were found. Further observations indicate that the appearance of the peroxisomal forms in immunofluorescence is dependent on the fixation procedure used. Whereas the fixation with methanol-acetone (-20 degrees C) or ethanol results in a punctate pattern with spherical particles, the use of formaldehyde/Triton X-100 fixation shows well-preserved tubules and rods. These observations may be of special importance for studies on the biogenesis of peroxisomes.

Acetone↗
PubMed1994

Well-differentiated (oncocytoid) neuroendocrine carcinoma of the larynx with multiple skin metastases: a brief report.

A 63-year-old woman presented with a history of increasing dysphagia of about two weeks duration. Laryngoscopy revealed a nonulcerated supraglottic epitheliomatous lesion that morphologically appeared well-differentiated and distinctly oncocytoid. Although the tumour lacked any criteria for malignancy such as cellular atypia, pleomorphism or necroses, it recurred twice after primary surgery and later gave rise to multiple painful skin metastases. The diagnosis of an oncocytoid differentiated neuroendocrine carcinoma of the larynx (laryngeal carcinoid) was made. Misinterpretation of laryngeal carcinoids is common, but can be avoided if one is familiar with this rare variant of laryngeal neoplasms.

Carcinoid Tumor↗
PubMed1994

Chicken antibodies to rabbit muscle actin with a restricted repertoire of F-actin recognition.

This report describes a polyclonal antibody against actin with unexpected and unusual properties. The antibody was raised in chicken immunized with a complex of DNase I and rabbit skeletal muscle actin, and purified from egg yolk by affinity chromatography. In Western blots, it reacted with alpha, beta and gamma isoforms of actin. In immunofluorescence and dot blot assays, however, it recognized selectively actin filaments in myofibrils, microvilli of brush border-type epithelium and the "comet tails" of the intracellular parasite Listeria monocytogenes, while it did not react with stress fibers and peripheral belts of fibroblasts and epithelial cells, respectively. This reactivity pattern is reminiscent of that previously described for a monoclonal mouse antibody raised against smooth muscle actin (Sawtell et al., Cell Motil. Cytoskel. 11, 318, 1988). The data presented in this study are consistent with the hypothesis that the chicken antibody recognizes an actin epitope/actin epitopes either accessible in only a subpopulation of microfilaments, or expressed only in a particular conformation of F-actin.

Actins↗
PubMed1994

Heterogeneity of peroxisomes in human hepatoblastoma cell line HepG2. Evidence of distinct subpopulations.

Peroxisomes in human hepatoblastoma cell line HepG2 have been studied using immunocytochemical, ultrastructural and biochemical techniques. By immunofluorescence, small spherical peroxisomes were seen next to rod-shaped and elongated forms. By electron microscopy and catalase cytochemistry, small particles with a diameter of 90 to 100 nm were found next to larger ones measuring up to 300 nm and some exhibiting tail-like extensions. Both the intensity of DAB-staining and the immunolabeling density for catalase were heterogenous in different peroxisomes. Contrary to a recent biochemical study, the enzyme alanine-glyoxylate-aminotransferase was found by double immunofluorescence and immunoelectron microscopy to be localized exclusively in peroxisomes of HepG2 cells. By Metrizamide density gradient centrifugation two populations of peroxisomes were isolated: a regular fraction banding at 1.20 g/cm3 with a mean diameter of 222 nm and a lighter peroxisome fraction banding at 1.14 g/cm3. The ratio of lipid beta-oxidation enzymes to catalase was significantly higher in peroxisomes with lower density than in the regular ones. These observations show clearly the existence of heterogenous populations of peroxisomes in HepG2 cells which may provide a useful model system for the investigation of biogenesis and metabolism of peroxisomes of human origin.

Centrifugation, Density Gradient↗
PubMed1994

[Value of abdominal ultrasound and skeletal scintigraphy in TNM classification of tumors in the head and neck area].

After establishing the diagnosis of carcinoma in the head and neck, routine examinations comprise chest x-ray, bone scan and abdominal ultrasound and are often initiated to exclude or confirm metastatic disease. Data are few on the frequency of metastases at the time of initial diagnosis and reliability of bone scanning and sonography to detect metastases. The aim of the present retrospective study was to define criteria for the use of these latter two methods of examination. The medical records of 382 patients with squamous cell carcinoma who were examined for the first time were analyzed during a four-year period. Bone scanning was performed on 360 patients, but suspect scintigraphic evidence of bone metastasis could be confirmed in only one patient. Only three of 367 patients undergoing abdominal ultrasound were found to have hepatic metastases. Reasons for a practical use of these two methods of examination are discussed.

Bone Neoplasms↗
PubMed1992

[Autologous blood transfusion in breast reduction].

Minimal risk blood transfusion is possible using autologous blood. When excessive blood loss is expected in reduction mammaplasty, autologous blood transfusion is recommended. Only three of eighty-one patients who underwent reduction mammaplasty in our department received homologous blood transfusions. Patients suffering from glandular hypertrophy are likely to loose significantly more blood during operation than patients with predominantly fatty breast tissue. Autologous blood transfusion should be recommended in cases of excessive breast hypertrophy, in patients afraid of transfusion-associated infections, and for forensic reasons.

Adult↗
PubMed1991

[Polydactyly of the hands. Recommendation for expanded classification].

The few anatomical findings summarized in the literature have now been expanded by our own anatomical dissections on four hands of still-born infants with postaxial polydactyly, and by intra-operative microsurgical investigations of 25 polydactylous hands. New experimentally-based knowledge of embryology helps interpret the morphogenesis and specific anatomy of polydactyly. It can be postulated that both the location and definite form of polydactyly are a function of the location and extent of initial excessive cell proliferation and disturbance of cell necrosis in the hand blastema. The conclusive discussion of special findings regarding anatomical structures shows regular pattern formations which lend themselves to a broader classification. The classification of malformations of the hand by Temtamy and McKusick was used as a framework for the classification of polydactyly, whether it was existing as an isolated form or as part of a syndrome. The osteological types I to VI found by Wassel in thumb duplication are confirmed by our anatomical findings. Special coding of anatomical findings enabled us to identify four variants and three forms, depending on the development of the digital palmar arteries and nerves. For the triphalangeal pre-axial fingers and the post-axial fifth finger, the five osteological types described by Müller and those described by Duhamel are increased to ten. Comparison with our anatomical findings shows four variants of these osteological types. For post-axial polydactyly, types XI through XIV, existing in three variants, have been defined.

Fingers↗