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Biomedical subjects

G Arnold

Publications and source records attributed to G Arnold.

At least 127 records · Page 7Linked to original sources
PubMed1989

Organization of collagen and other extracellular material in anterior capsular cataract.

Capsular cataract takes the form of a white-grey opacity appearing under the anterior lens capsule (anterior subcapsular cataract). The capsule is wrinkled through the action of myofibroblast-like cells developed from the anterior lenticular epithelium. The myofibroblast-like cells also produce collagen that takes on a dysplastic appearance. Collagenous microfibrils accumulate to form fibre-like aggregations. These aggregations represent an abnormal collagen density (collagen condensation or attraction) in comparison to normal collagenous fibrils and fibres. Within the anterior capsular cataract 4 topological regions may be distinguished: Cell regions (1), stratification regions (2), aggregation regions (3), and intermediate regions (4). It is postulated that these regions represent different stages in the maturation and degradation of collagen, in the absence of phagocytic elements.

Cataract↗
PubMed1989

[Life after urostomy. A retrospective study].

The study reported, which was based on a questionnaire and psychological tests, examined cystostomy patients with respect to the work-up and acceptance of their altered body. It was noted that 30% of the patients judged their situation as good, and 25% could accept the cystostomy, but a great many has to live with sexual disturbances, reduced social mobility, increased dependence, and psychic consequences; some had to give up their jobs. Sex, earlier psychosomatic diseases, developmental disorders in early childhood, which influence the personality, significantly affect the acceptance of the stoma. The problems are discussed. Suggestions are made, which include a plan for a holistic therapy.

Adaptation, Psychological↗
PubMed1989

[Thermoanalytic studies of bundles of collagen fibers with biomechanical methods].

Thermomechanical experiments were performed on collagenous fibre bundles of tendons from cattle and man. Subsequent to extensions of fibre bundles the particular amount of length was kept constant (isometric conditions). At the end of the relaxation under approximative equilibrium conditions (mechanical steady state phase) the temperature was raised proportional to time (with linear temperature rate). In the range between 0 and 43 degrees Celsius the isometric force decreased in form of an approximately straight line. This line was declined at 43 degrees C (thermal depression region). After the thermal shrinkage region (62-64 degrees C) the isometric force increased considerably. In this ascending part of the isometric thermal mechanogram 2 domains of slope can be observed. They are designed as lower and upper thermal transition region. In the ascending part of the isometric thermal mechanogram an isothermal relaxation is to be seen under constant temperature conditions. The isothermal isorheological line and isothermal superelevation are described. The results are discussed in context with their meaning for functional anatomy, muscle physiology, supercoolings, and burnings.

Animals↗
PubMed1988

The use of Quetol 651 for the post-embedding immunohistochemical demonstration of gamma-aminobutyric acid on semithin sections.

Quetol 651 was used as an embedding medium for the demonstration of gamma aminobutyric acid (GABA) in semithin sections by the peroxidase-anti-peroxidase method. In order to demonstrate the immunoreactivity, the embedding medium was partially dissolved using absolute ethanol containing 0.8-1 M NaOH or KOH for 5-7 min. The experimental procedure was elaborated by testing the GABAergic sites in the endings surrounding the small neurones of the anterior exterolateral nucleus of a mormyrid fish and in the pyramidal cells of the electrosensory lateral line lobe of gymnotoid fish by applying anti-GAD (glutamic acid decarboxylase) antiserum. To test the general validity of the use of Quetol 651, GABAergic sites were also identified in the central nervous system of an insect, the honey bee, with anti-GABA and anti-GAD antisera. The intensity of labelling revealed by immunoperoxidase applied to Quetol 651-embedded semithin sections, demonstrated high precision and gave good resolution for light microscopical observations.

Animals↗
PubMed1988

[Function and morphology of intraperitoneal segmental pancreas allotransplants with cyclosporin monotherapy in the dog--a comparison of 4 drainage procedures of exocrine secretions].

Dogs which had received cyclosporine A for immunosuppression were investigated to elucidate functionality and morphological alterations in pancreas allografts, with enteral, vesical, peritoneal or occluded exocrine drainage. None of the animals with enteral drainage survived the first four postoperative weeks, with lethal infections being responsible for allograft failure. Full functionality three months from transplantation was recorded from three of seven transplants with ductal occlusion and unobstructed drainage into the abdominal cavity. Ductal occlusion was repeatedly accompanied by pancreatitis and pseudo-cysts. Fibrotisation of the organ and loss of endocrine islets of pancreas were recordable from these cases just as from grafts with unobstructed drainage into the abdominal cavity. Drainage of exocrine secretion into the bladder yielded good success in one of seven animals and was morphologically and functionally characterised primarily by occlusive metaplastic ossification along the transition to the anastomosis.

Animals↗
PubMed1988

[Global and regional left ventricular function following acute coronary artery occlusion and emergency aortocoronary venous bypass operation].

Complications following percutaneous transluminal coronary angioplasty (PTCA), such as coronary artery occlusion, spasm, or dissection, frequently require urgent surgical intervention. Out of 26 patients from our hospital, 12 who underwent emergency coronary bypass grafting because of balloon catheter complications with a total ischemic time of 100-255 min, were restudied in the late postoperative period by clinical examination and by coronary and left ventricular angiography. Left ventricular angiograms were evaluated quantitatively for global and regional function using the AVD system (Siemens Elema, Erlangen). Electronmicroscopic results from myocardial biopsy samples, taken intraoperatively from the presumed center of the ischemic zone, were compared with the clinical results. An improvement of left ventricular function parameters could be seen in patients with reperfusion intervals within 130 min. In the case of intermittent perfusion of the occluded vessel (catheter perfusion with arterial blood, intermittent spasm) operative revascularization proved to salvage jeopardized myocardium. There was a close correlation between the degree of left ventricular dysfunction and histological results, coronary morphology and clinical staging. In conclusion, the efficacy of myocardial protection by emergency bypass surgery depends mainly on coronary morphology and above all on reperfusion intervals.

Adult↗
PubMed1988

[Diagnostic significance of angioscopy in patients with coronary heart disease].

Coronary angioscopy (CA) using ultrathin fiberscopes was performed in 30 patients with coronary heart disease during cardiac catheterization and in 11 patients during bypass surgery. For percutaneous CA the angioscope was introduced from the femoral artery through a 9F guiding catheter. During short-time occlusion of the coronary ostium by the tip of the guiding catheter the viewing field was flushed with Ringer's solution. Intraoperative CA was performed both by the retrograde and antegrade way during flushing with cardioplegic solution. Percutaneous CA was successful in 57% of patients. 13 patients showed eccentrically and irregularly shaped stenoses and 3 of these patients had an additional plaque rupture. In 2/5 patients CA after PTCA revealed intimal dissections not visualized by angiography. Intraoperative CA was successful in 9/11 patients. In 3 patients nonocclusive thrombi were found at the site of the coronary lesion. Additionally we studied the efficacy of angioscopic guidance during intravascular radiofrequency application. In 11/11 thrombotically occluded peripheral vessels this new method allowed a nearly complete recanalization. There was only one perforation of the vessel. We conclude, that CA is a powerful diagnostic tool providing prognostically relevant information in the diagnosis of coronary heart disease.

Animals↗
PubMed1988

[Aggressive mediastinal fibrosis, a rare cause of superior vena cava obstruction--case report and review of the literature].

An aggressive mediastinal fibrosis was found to be a cause of superior vena caval obstruction in 1 to 2% of patients. Symptoms can be discrete for a long time, but the progressing disease can cause many symptoms. A 56-year-old man who, for half a year, suffered from thoracic pain during deep inspiration, and then rapidly developed superior vena caval obstruction caused by aggressive mediastinal fibrosis is discussed. The operative treatment consisted in complete replacement of the superior vena cava.

Fibrosis↗
PubMed1988

Bidirectional transvenous/subcutaneous defibrillation of ventricular fibrillation in dogs: success rates, energy requirements, currents, voltages and impedance.

Four hundred and thirteen defibrillations of alternating current-induced ventricular fibrillation were performed in 10 halothane-anaesthetized dogs (body weight: 24.5-30.5 kg). Success rates, energy demands, currents, peak voltages and impedance were determined. A transvenous catheter electrode system (Medtronic 6880, right ventricular apex and superior vena cava, distance 100 or 150 mm) and subcutaneous patch electrodes (Intec 67 L, 2nd/3rd and/or 3rd/4th left intercostal space) were used for bidirectional defibrillation. Loading voltages ranged from 600 to 850 V. With an electrode distance of 100 mm and a pulse duration of 2 ms separated by 1 ms, success rates were 100%, 40% and 0% for 850.650 and 600 V, respectively. With a 3-ms pulse duration, the corresponding rates were 100%, 60% and 50%. With a 2-ms pulse duration, successful defibrillation was achieved with energies lower than 15 J in 27%, with energies between 15 and 20 J in 77%, and 100% with energies higher than 20 J. Defibrillation currents were 4.4-9.3 A for pulse 1 (superior vena cava/ventricular apex) and 6.3-13.4 A for pulse 2 (patch/ventricular apex), respectively. Effective peak voltages ranged from 510 to 787 V and from 514 to 777V and averaged 89.6% of the loading voltages. Impedance values (peak voltage/current) were 75.5-117.7 (pulse 1) and 51.7-94.9 Ohms (pulse 2). Fifty consecutive defibrillations in one animal resulted in a decrease of impedance (114.6 to 84.9 Ohms, pulse 1:75.4 to 53.0 Ohms, pulse 2). Defibrillation of ventricular fibrillation can be achieved with acceptably low energies using a bidirectional transvenous/subcutaneous system, avoiding thoracotomy and general anaesthesia for implantation of the defibrillation system.

Animals↗
PubMed1987

Complications after modern filter operations in glaucoma.

As long as the indications and limitations of laser trabeculoplasty have not yet been established by follow-up over several years, conventional surgical filter operation will not be superfluous. The reduction of the complications brought about by introduction of the scleral flap technique is described. Apart from cicatricial obliteration of the filtering zone, bulbar hypotension due to overfiltration as well as to external fistula and above all the resulting ciliary body-choroid detachment still occurs after trephination with the scleral flap (goniotrephination, trabeculectomy). Attention is drawn to the tension of the scleral flap adapted to the normalized intraocular pressure and reliable preclusion of an external fistula by perfusion test at the end of the operation. The membrane formation probably deriving from the internal Tenon's capsule which leads to a 'pseudofiltering bleb' is discussed as a rare complication (1.5%) which is of basic interest.

Cicatrix↗
PubMed1986

Epithelioid hemangioendothelioma. Report of a case with immuno-lectinhistochemical and ultrastructural demonstration of its vascular nature.

The epithelioid hemangioendothelioma (EHE) is a rare vascular tumour of borderline malignancy, first described as a separate entity in 1982 by Weiss and Enzinger. The abundant cytoplasm of endothelial cells mimiking epithelioid appearances, prominent cytoplasmic vacuolization and barely perceptible lumina even in reticulin stains may result in EHE being mistaken for a signet ring cell carcinoma. In our case, difficulties in differential diagnosis were enhanced by the location of the tumour within an inguinal lymph node. The usefulness of FVIIIR: Ag- and UEA I- histochemistry in ascertaining the endothelial nature of this tumour is demonstrated, in correlation with electron microscopic data. The different reaction sites of these markers are striking and typical: FVIIIR: Ag displays a granular or diffuse cytoplasmic reaction, whereas UEA I provides a linear staining of vacuoles and luminal surfaces.

Adenocarcinoma, Mucinous↗
PubMed1986

[Genesis of papillar pit. Microscopy study in a newborn infant].

The rare microscopic picture of a pit of the optic disk is described. The recess extended from the physiological cup of the optic disk to the former cleft of the optic stalk at the point of entry of the ophthalmic artery. There was no disk coloboma. This result is in good agreement with von Szily's paper on the genesis of crater-like holes in the optic disk as a residue of the cavity of the primordial epithelial papilla. In this case there was no communication of the vitreous cavity with a subretinal space, which is suspected of being the cause of the frequent concomitant serous detachment of the macula.

Abnormalities, Multiple↗
PubMed1986

No evidence for serotonergic-adrenergic interactions in the canine total cardiovascular system.

Possible in vivo interactions of serotonin and noradrenaline were investigated in 7 anesthetized mongrel dogs. The hemodynamic effects of three different doses of serotonin (10, 50 and 100 micrograms/kg/min) were analyzed with and without noradrenaline treatment (0.05-0.1 micrograms/kg/min). There were no significant differences in peripheral and cardiac responses between the pure serotonin effect and the hemodynamic effects of a parallel serotonin-noradrenaline infusion. The discussed amplifying effect of serotonin on the adrenergic system could not be observed in the total canine cardiovascular system.

Animals↗