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A new method for the distillation of glutaraldehyde to obtain the monomeric form is presented. The monomer is obtained after only one distillation and it has a purification index (Pi) smaller than 0.20.

The SEM-pictures represent a keratoconus in a 59-year-old patient with a Descemet rupture, which had led to a so-called Kammerwassereinbruch, where the failure of the endothelial structure has become manifest in the epithelium. In the Descemet-rupture the onset of stromal pathology is observable, while outside the rupture severe degradation of endothelial cells is seen. This is manifested as cell-membrane perforation, loss of cell contents and oedema formation in general. On the epithelial side the pathology is expressed as cell-membrane degradation and the presence of very irregularly shaped, sometimes swollen and in other cases shrunken, epithelial cells, in particular in the areas of the surface depressions. The topographical correspondence of these pathological phenomena on the endothelial and the epithelial sides is stressed.

Non-auditory effects of noise were studied among 539 male workers from seven industries. The LAeq, assessed by personal noise dosimetry, has been used to study acute effects. Various indices of total noise exposure, involving level and duration, were developed for long-term effect studies. In the analysis close attention was paid to prevent confounding, e.g. by other adverse working conditions. As expected, hearing loss increased with total noise exposure. Tinnitus was related particularly to hearing loss. Dizziness and hoarseness, however, were not related with noise exposure in this study. Also no correlation could be demonstrated between blood pressure and total noise exposure after correction for age, relative weight and various confounding variables. Use of hearing protection, selection processes and incomplete analysis of interactions between independent variables are suggested for possible explanation. About two-thirds of the workers reported noise annoyance. Various aspects were mentioned, such as irritation, surprise and impairment of communication and perception. Mentally stressful tasks appeared to be the most noise-sensitive. Particularly annoying noise sources, mental work load and time pressure had a relatively large impact on noise annoyance in comparison with the influence of noise level (LAeq) itself. Stress responses were not simply related to the noise exposure level, although consistent positive relations could be demonstrated between symptoms of stress and noise annoyance. Various findings led to the conclusion that noise exposure together with stressful mental activities may lead to disturbed concentration, irritation and annoyance. Experienced stress in turn may render workers more susceptible to noise. To overcome some limitations of this study, cohort studies and studies designed to assess interaction-effects are recommended.

The ultrastructure of a new type of vascular graft, prepared from a mixture of polyurethane (95 weight %) and poly-L-lactic acid (5 weight %), was examined six weeks after implantation into the abdominal aorta of rats. These microporous, compliant, biodegradable, vascular grafts function as temporary scaffolds for the regeneration of the arterial wall. Smooth muscle cells, covering the grafts, regenerated a neo-media underneath an almost completely regenerated endothelial layer (neo-intima). These smooth muscle cells varied in morphology from normal smooth muscle cells to myofibroblasts. They were surrounded by elastic laminae and collagen fibers. Macrophages, epithelioid cells, multinucleated giant cells, fibroblasts and capillaries were present in the disintegrating graft lattices. The epithelioid cells and multinucleated giant cells engulfed polymer particles of the disintegrating grafts. The regeneration of the endothelial and smooth muscle cells is similar to the natural response of arterial tissue upon injury. The presence of macrophages, epithelioid cells, multinucleated giant cells, fibroblasts and capillaries in the graft lattices resembles the natural response of tissue against foreign body implants. Both of these responses result in the formation of a neo-artery that possesses sufficient strength, compliance and thromboresistance to function as a small caliber arterial substitute.

The cellular origin and development of radiation-induced atheromatous plaques in the carotid artery of the hypercholesterolemic rabbit have been studied morphologically from a few hours post-irradiation up to several weeks later. As early as 8 h following local X-irradiation (500 or 1,000 rad) mononuclear cells, presumably blood monocytes, enter the subendothelial space. The cells have disappeared again 10 days post-irradiation in normocholesterolemic animals. In irradiated hypercholesterolemic animals, however, the invading mononuclear cells transform into lipophages and become so-called foam cells, visible from the second day post-irradiation. The number of lipophages increases with time resulting in plaques of about 5-10 cell layers after 20 days. From 20 days post-irradiation onwards smooth muscle cells enter the plaque by migrating from the tunica media through the fenestrations of the lamina elastica interna. Smooth muscle cells are found to contain less lipid vacuoles than monocyte-derived lipophages. At 30 days post-irradiation the smooth muscle cells have formed parallel layers in the luminal side of the plaque encapsulating an inner core of foam cells and other material. The morphology of the plaque at 30 days post-irradiation is similar to that reported for advanced plaques developing in rabbits by mere cholesterol feeding over a relatively long period. In irradiated normocholesterolemic and in non-irradiated hypercholesterolemic rabbits plaques are not observed in the carotid arteries during the experimental period. The early involvement of blood monocytes has been separated from the later role of medial smooth muscle cells in radiation-induced plaque formation. The results suggest that the underlying process in this lesion may be understood in terms of a sterile inflammation, complicated by an immediate fatty degeneration and followed by repair phenomena. The combination of hypercholesterolemia and ionizing radiation may serve as a useful experimental model for further studies in various animal species on why and how plaques originate, develop or regress and how they could possibly be prevented. The relevance of the results to radiotherapy in humans is mentioned briefly.

The manufacture of a suturing needle either from a 0.24 mm phi stainless steel capillary or a 30 G injection needle, as examples of an intermediate technology appropriate for developing countries, is followed step by step with the SEM.

Microporous, compliant, biodegradable vascular grafts prepared from a mixture of polyurethane (95% weight) and poly-L-lactic acid (5% weight) can function as a temporary scaffold for the regeneration of the arterial wall in small-caliber arteries. This study was undertaken to document the sequential events leading to this regeneration. Therefore, polyurethane/poly-L-lactic acid vascular grafts were implanted into the abdominal aorta of rats (N = 28) and were harvested at regular intervals from 1 hour up to 12 weeks after implantation. The implants were evaluated by means of light and electron microscopy. At each time of harvesting, the implants were patent and showed arterial pulsations. No stenosis or dilatation was observed. Endothelial cells grew from the adjacent aortic intima across the anastomoses, from day 6 onward, to form an almost complete neointima after 6 weeks of implantation. Smooth muscle cells also grew from the adjacent aortic media over the graft lattice through the platelet-fibrin coagulum from day 6 onward. The smooth muscle cells, predominantly longitudinally arranged at week 6, but also circularly arranged in some areas at week 12, formed a neomedia in which elastic laminae regenerated. Polymorphonuclear leukocytes and monocytes initially invaded the graft lattices. Fibroblasts, histiocytes, and capillaries grew from the perigraft tissue into the polyurethane/poly-L-lactic acid lattices from day 6 onward, which resulted in the formation of a neoadventitia. The polyurethane/poly-L-lactic acid lattices started to disintegrate from day 12 onward. The regenerative processes in the disintegrating polyurethane/poly-L-lactic acid grafts resulted in the formation of neoarteries, which were of sufficient strength, compliance, and thromboresistance to function as small-caliber arterial substitutes.

Human cataractous lenses from patients of advanced age (101 & 85 year) were investigated by SEM. Various aspects of the cataract morphology could be observed. Even when the overall shape of the lens fibres had remained unchanged (although the typical ball and socket interconnections were barely visible) the homogeneous fibre content had changed into fibrillar and/or granular material, or the lens fibres had been (partly) hollowed out. Where there was shrinkage of the originally hexagonally-shaped lens fibres to a more or less rounded form with a wrinkled surface, the contents had changed into granular material with low density. Both granular and fibrillar material could account for a substantial increase in light scattering, resulting in a considerable decrease in vision through the lens.