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Biomedical subjects

A Ewert

Publications and source records attributed to A Ewert.

At least 19 recordsLinked to original sources
PubMed2007

[Indications and techniques for wrist arthroscopy].

After considering the anatomy of the wrist, the technical requirements for wrist arthroscopy are discussed. This method is used as an additional diagnostic procedure and staging procedure as well as a therapeutic technique. Complications, which are rare, most commonly involve nerve irritation, damage to cutaneous nerves and extensor tendons. Lose bodies can be removed arthroscopically, however, arthroscopically assisted fracture treatment or the removal of ganglions are uncommon. Approaches are lateral and oriented on the extensor tendons or other anatomical landmarks. Arthroscopy is especially useful by carpal instability as it offers many possibilities, not only diagnostically but also therapeutically.

Arthroscopes↗
PubMed2006

[Complex proximal humerus fractures--management with a humeral head prosthesis? Clinical and radiological results of a prospective study].

BACKGROUND: Proximal humerus fractures are one of the most common fractures in elderly patients. In the treatment of complex proximal humerus fractures, primary hemiarthroplasty is still discussed controversially. The present study was undertaken to evaluate the results of primary hemiarthroplasty in the treatment of proximal humerus fractures with a modular prosthesis (EPOCA, Fa. Argomedical, Gifhorn, Germany). MATERIAL AND METHODS: A prospective study of 24 patients with complex humerus fracture (NEER: IV/4, V/4, VI/4, and head split fracture) was performed from August 2000 to December 2002. Mean age was 75.6 years (range: 52-92); 18 patients were seen for follow-up after 0.5 and 1 year, respectively. The Constant-Murley score (max. 100 points) and the UCLA Rating System (max. 35 points) were calculated for functional assessment of the operated shoulder. RESULTS: Fifteen patients (83%) were pain free 1 year after the operation. The Constant-Murley score improved from 52 (+/-17) to 56 (+/-18) at the second follow-up after 1 year. On the contralateral side a score of 86 (+/-10) was assessed (p<0.05 vs operated side). Correspondingly, shoulder function according to the UCLA Rating System improved [25 (+/-4); 27 (+/-5)]. CONCLUSIONS: Osteoporotic bone of older patients often may not permit stable internal fixation of complex proximal humerus fractures. In these situations primary hemiarthroplasty is the treatment of choice.

Aged↗
PubMed2003

[Radio-radial external fixation in the treatment of distal radius fractures allows for free wrist motion].

INTRODUCTION: Joint bridging external fixation in the treatment of distal radius fractures restores radial length, whereas anatomic reduction of articular fragments is difficult. Immobilisation of the wrist joint is a further disadvantage. An extraarticular hybrid fixation of distal radius fractures was introduced that facilitates fracture reduction, safe retention and allows for free wrist movement. METHODS: 30 consecutive patients with extra- and intraarticular comminuted fractures of the distal radius were treated with an extraarticular radio-radial external fixation employing a modified Ilizarov hybrid fixation technique. The operative procedure is described in detail. A clinical and radiological evaluation was carried out on the first and seventh day as well as 6 weeks postoperatively after implant removal. RESULTS: Anatomic reduction was achieved in 24 cases (80%). On the first postoperative day dorsiflexion was 30%, palmar flexion was 51% and pronation/supination was 60%/70% of the uninjured side. Six weeks postoperatively all fractures united. Wrist motion of the affected side was more than 80% of the unaffected side. Neither extensor tendinitis nor pin loosening in the distal fragment did occur. CONCLUSION: The technique of extraarticular hybrid fixation is safe and reliable in the treatment of comminuted fractures of the distal radius. It allows for early wrist movement in the immediate postoperative period.

Adult↗
PubMed2001

Oxidative stress increases endothelin-1 synthesis in human coronary artery smooth muscle cells.

Endothelins, nitric oxide, and oxygen-derived free radicals decisively regulate vascular tone. An imbalance in the biosynthesis of these substances in pathophysiologic conditions may trigger vasospasm and promote the development of atherosclerosis. Previous studies have shown that oxygen-derived free radicals can increase the synthesis of endothelin-1 in cultured endothelial cells. Interestingly, conditions of increased oxidative stress within smooth muscle cells as induced by angiotensin II infusion or hypercholesterolemia have been shown to be associated with increased autocrine synthesis of endothelin-1. Because endothelin-1 formed in smooth muscle cells can trigger hypersensitivity to vasoconstrictors, we tested whether oxidative stress per se may affect endothelin expression in vascular smooth muscle cells. Cultured human coronary artery smooth muscle cells were exposed to oxidative stress generated by the xanthine/xanthine oxidase reaction or by hydrogen peroxide. Preproendothelin-1 mRNA content was quantitated by means of quantitative polymerase chain reaction and endothelin-1 protein was measured by radioimmunoassay. Incubation with xanthine/xanthine oxidase significantly increased preproendothelin-1 mRNA synthesis, whereas GAPDH remained unchanged. Likewise, xanthine/xanthine oxidase also led to a dose-dependent increase of intracellular endothelin-1. The increase in ET-1 expression induced by xanthine/xanthine oxidase was significantly inhibited by superoxide dismutase but not by catalase. We conclude that oxygen-derived free radicals can stimulate the synthesis of endothelin-1 in endothelial and vascular smooth muscle cells by increasing preproendothelin-1 mRNA content and that this effect is mediated predominantly by superoxide anions. We therefore have identified a new mechanism in the interaction of oxidative stress and endothelin-1 expression in smooth muscle cells that may have important implications in diseases such as atherosclerosis and hypertension.

Cells, Cultured↗
PubMed1998

[MRI-assisted bile duct drainage: evaluation of passive catheter imaging in an animal model].

PURPOSE: To investigate interactive MR-assisted bile duct drainage in pigs with the passive visualization technique using near real-time imaging. METHODS: 8 bile duct drainages were placed in an open low-field MR system (0.2 Tesla) in 4 pigs with surgically induced cholestasis. After planning the intervention with magnetic resonance cholangiography (MRC), both the puncture and catheter placement were interactively guided using a fast T2-weighted true FISP sequence. RESULTS: MRC enabled interventional planning in all puncture attempts. Punctures were unproblematic in all attempts, the bile ducts were punctured 6 times after the first and twice after the second attempt. Placement of the passively visible catheter was successful in all animals. The applied sequence enables interactive fluoroscopy-like positioning of the devices. CONCLUSION: The procedure introduced here enables reliable and fast placement of a bile duct drainage in an animal model using a low-field MR system.

Animals↗
PubMed1997

[Is routine tumor after-care after gastrectomy sensible?].

Only 22.3% of patients with recurrence after potentially curative gastrectomy are discovered in asymptomatic stages. Their prognosis is not different from those with symptomatic recurrence. Routine follow-up after gastrectomy can be abandoned.

Aftercare↗
PubMed1993

Survival of group A streptococci in dried human blood.

The resurgence of streptococcal infections in the USA and Europe and their high incidence in other parts of the world prompted an examination of the survival and maintenance of virulence of group A streptococci. Human blood containing group A streptococci was placed on small pieces of sterile paper towelling and allowed to dry at room temperature. At periods of 2, 8, 15 and 20 weeks later, the paper with the dried blood was placed in Todd-Hewitt broth and incubated at 37 degrees C overnight. All the samples tested at 2 weeks grew in broth, and with only one exception, grew in fresh human blood provided by five donors. At 8 weeks only two of the 10 strains failed to grow in broth; seven of the eight viable cultures also grew in blood. At 15 and 20 weeks after drying the eight cultures were still viable. Since seven were able to grow in fresh blood as well as in broth it is assumed that their virulence factor(s) had been retained.

Aged↗
PubMed1992

Food ingestion and digestive enzymes in larval Aedes aegypti and Ae. albopictus (Diptera: Culicidae).

Frequency of the labral brush movements of first, second, and fourth instars of Aedes aegypti (L.) and Aedes albopictus (Skuse) was studied comparatively in the laboratory. A frequency of 197 strokes per min for the first and second instars was observed in the former species compared to 118 strokes per min in the latter species. A faster ingestion rate of algal cells also was observed in first and second instars of Ae. aegypti (mean 57.5 cells per s) compared with first and second instars of Ae. albopictus (mean 22.4 cells per s). The digestive enzymes chymotrypsin (EC 3.4.21.1) and trypsin (EC 3.4.21.4) were more active in the peritrophic membrane (including food contents) than in the midgut epithelium of both species. Chymotrypsin activity in 11-d-old third and fourth instars of Ae. albopictus was 28 times higher than in the corresponding stadia of Ae. aegypti, indicating that the former species may have a superior enzymatic process for digesting food proteins.

Aedes↗
PubMed1990

Sarcoptes scabiei in histopathologic sections of skin in human scabies.

The usual methods of diagnosis remove Sarcoptes scabiei from its habitat. Thus, one has no appreciation of the host-endoparasitic interaction, especially the pathologic response of the surrounding tissue and the means by which the mite survives and lives its life cycle in the skin. The biopsy specimen described in this article demonstrates the tissue reaction that can be correlated with clinical symptoms. It also clearly depicts the actual position, morphological features, and developmental cycle of the mite in the skin.

Aged↗
PubMed1989

Interspecific competition among Aedes aegypti, Ae. albopictus, and Ae. triseriatus (Diptera: Culicidae): larval development in mixed cultures.

Interactions among the larvae of Aedes aegypti (L.), Ae. albopictus (Skuse), and Ae. triseriatus (Say) were studied in trispecific and bispecific mixed populations under laboratory and field conditions. Competitive stress (as evidenced by the average time to first, 50, and 75% pupation and the total pupation periods for mixed populations of each species in comparison with their single species controls) was more pronounced in mixed cultures reared in glass jars in the laboratory than in tires under field conditions. In the laboratory, the larval development of Ae. aegypti reared together with Ae. albopictus or Ae. triseriatus, or both, larvae was accelerated significantly. Conversely, the time to pupation for Ae. albopictus and Ae. triseriatus was delayed when reared with Ae. aegypti. However, the average wing length of female Ae. albopictus and Ae. triseriatus was greater in the mixed cultures than in single species cultures. These data indicated that the effect of intraspecific competition was greater than interspecific competition. Adequate food and higher temperature appeared to promote rapid development and higher survival of the immature stages of the three Aedes species in tires placed in the field. In general, Ae. triseriatus larvae required a longer period for larval development and had greater larval mortality than either Ae. aegypti or Ae. albopictus. In mixed populations of Ae, albopictus and Ae. aegypti in the jars and food-rich tires, the periods needed to attain first, 50, and 75% cumulative pupation were not significantly different than in single species controls. We conclude that no clear-cut displacement occurred in mixed experimental populations of Ae. aegypti and Ae. albopictus.

Aedes↗
PubMed1988

Edema resulting from experimental filariasis.

Domestic cats and patas monkeys were infected with Brugia malayi so that the worms localized in the regional lymphatics of the hind legs. Reaction to the filarial parasites resulted in visible local edema in cats and disruption of normal lymph flow in the monkeys. Edematous tissue was examined grossly and by light and electron microscopy. Lymph flow patterns were examined by direct observation following injection of lymph staining dye and reflection of the skin, by X-ray following injection of radio-opaque contrast media, and by lymphscintigraphy after subcutaneous injection of radioisotopes. Clinical edema occurred in cats but not in monkeys. However, disruption of normal lymph flow in monkeys infected with Brugia could be demonstrated by lymphscintigraphy.

Animals↗
PubMed1988

Degenerative changes in lymphatic endothelium of jirds infected with Brugia pahangi.

The quantitative changes of cytoplasmic vesicles and vacuoles in lymphatic endothelial cells of the mongolian jirds associated with Brugia pahangi infections were observed by transmission electron microscopy. The present study revealed a decrease in the proportion of cytoplasm occupied by vesicles and in the number of cytoplasmic vesicles in endothelial cells from lymphatic vessels harboring B. pahangi at 3, 4, and 10 mo after infection (3.55, 3.36, and 2.55 vesicles/micron 2, respectively) when compared with cells from uninfected control vessels (7.03 vesicles/micron 2). On the contrary, there was an increase in the area of vacuoles in endothelial cells of jirds at 3, 4, and 10 mo postinfection. The mean +/- SD diameter of vesicles in cells from lymphatic vessels at 10 mo after infection was significantly smaller (78.6 +/- 5.6 nm) compared to vesicles in uninfected vessels (87.5 +/- 9.7 nm).

Animals↗
PubMed1987

Laboratory transmission of lymphatic filariasis by vector mosquitoes.

Aedes togoi and Ae. aegypti were used to examine the transmission potential of Brugia pahangi to one of its natural hosts, the domestic cat. Although a larger proportion of microfilariae taken in by Ae. togoi developed into infective larvae, the total number of B. pahangi larvae recovered from a cat exposed to Ae. aegypti was larger than from a cat exposed to Ae. togoi. Factors influencing the transmission dynamics included: development of microfilariae to infective larvae; survival of mosquitoes; willingness to take repeated blood meals; and proportion of infective larvae that egress from mosquitoes during the feeding process. From 19 to 25% of infective larvae were transferred to a susceptible host. The feasibility of using a Brugia-cat model to do comparative vector efficiency studies was demonstrated.

Aedes↗
PubMed1986

Evolution of lymph thrombi in experimental Brugia malayi infections: a scanning electron microscopic study.

Lymph thrombi in cats experimentally-infected with Brugia malayi were examined by scanning electron microscopy. A variety of morphological forms were noted and it appeared that thrombi undergo a maturation process characterized by at least three transitional phases. Initially, the thrombus consists of erythrocytes encased in fibrin (Phase I). Phase II thrombi are characterized by the appearance of phagocytic cells and fibroblasts on the surface of the thrombus. At the end of the maturation process, the thrombus surface consists solely of fibroblasts or endothelial cells, perhaps derived from the vessel wall (Phase III). Occlusion of the lymphatic lumen by thrombi and the accompanying inflammatory response triggered by B. malayi infection may be a major factor in the pathogenesis of lymph stasis in this disorder.

Animals↗