Supporting, microporous, elastomeric degradable prostheses to improve the arterialization of autologous vein grafts

Arterial reconstructions with vein grafts fail more frequently than with arterial grafts. One of the causes of graft failure is damage due to overstretching of the graft wall. Overstretching is caused because the vein graft, which has a poorly developed medium, cannot withstand the arterial blood pressures. The aim of this study is to evaluate whether damage due to overstretching can be prevented and a gradual adaptation of the vein graft to the arterial blood pressures can be induced by applying a microporous, elastomeric, degradable prosthesis around the vein graft. Therefore, autologous vein grafts (length 1.0cm) with and without supporting prostheses (composite vein grafts and control vein grafts, respectively) were interposed into both carotid arteries of rabbits. Microporous, elastomeric, biofragmentable polyurethane-based prostheses and microporous, elastomeric, biodegradable prostheses made of poly--caprolactone or a copolymer of -caprolactone and 3.6-dimethyl-1,4-morpholine-2,5-dione with a monomer ratio of 95.5:4.5 were prepared. The grafts were evaluated up to 6 wk after implantation. The control vein grafts showed severe destructive changes such as de-endothelialization, disruption of the media with oedema, degradation of the elastic laminae and infiltration of polymorphonuclear leucocytes into the vein graft wall, leading eventually to a fibrotic wall. In contrast, the composite vein grafts showed a preservation of the smooth muscle cell layers and the elastic laminae with only few polymorphonuclear leucocytes infiltrated into the vein graft wall. Moreover, the wall of the vein graft gradually increased in thickness by the formation of regular circularly oriented cellular layers beneath the original longitudinally oriented smooth muscle cell layers, indicating a gradual adaptation of the vein graft to the arterial conditions. It appeared that the arterialization rate depended on the degradation rate of the supporting prostheses. Microporous prostheses made of a copolymer of -caprolactone and 3,6-dimethyl-1,4-morpholine-2,5-dione with a monomer ratio higher than 95.5:4.5 are recommended to support the vein grafts

Haagse groei versus Leidse krimp. Een vergelijking van de ruimtelijke ontwikkelingen in twee Hollandse steden tussen 1700 en 1870

After the economic prosperity of the Golden Age, the Netherlands entered a period of stagnation and decline, which lasted roughly from 1700 to 1850. During this period the city of Leiden saw its population shrink dramatically from some 53,000 inhabitants to around 36,000. The Hague, by contrast, experienced strong growth, from 30,000 to 52,000 inhabitants. This article compares spatial developments in these two northern Dutch cities based on development maps generated by a detailed analysis of historical city street maps. Such visual documentation of urban spatial changes in this period is still an infrequently used method. A comparison of the unique growth with the strong decline during three successive time periods, serves to highlight the spatial effects of both phenomena. 1700–1750/60 In 1700, the size of both cities within their outer defensive canals was much the same, but Leiden, thanks to a flourishing textile industry in the seventeenth century, was much more densely populated and had around twice as many inhabitants and houses as The Hague. In the administrative capital of The Hague, where the large number of wealthy citizens prompted an influx of servants, densification is most apparent within the canal ring. In Leiden, the stagnation of both the economy and the population meant that spatial change was minimal. In 1750 The Hague had around 35,000 inhabitants, almost as many as Leiden had in 1760, when its population stood at around 37,000. 1750/60–1830 Once again there is very little new construction to be seen in Leiden; instead there are many new open areas caused by demolition and the gunpowder ship disaster of 1807. In The Hague there is some new construction but much less than during the previous period. In both cities the largest new structure is an army barracks. The court capital filled in more canals and excavated a section of the Scheveningen Canal. In Leiden the ramparts lost their defensive function whereupon they were partially transformed into a park. By the end of this period, The Hague had 56,105 inhabitants, some 16,000 more than Leiden, but it still had a more open character. 1830–1870 The Hague underwent considerable densification inside the canal ring as well as extensions north and south of the city. The number of new tenements built on inner yards in The Hague can give a distorted impression, as can the number of demolished buildings in Leiden, because the 1870 maps were much more detailed. In Leiden the advent of new factories prompted new construction on the former city walls. The Hague, too, became a major industrial player, while continuing to profit from its function as the centre of government. In 1870, The Hague had almost twoand-a-half times as many inhabitants as Leiden (92,000 versus 39,000), but within the canal girdle Leiden was still more densely built up. Between 1700 and 1870, The Hague developed into one of the Netherlands’ biggest cities, which it still is. Leiden plummeted from second place to the middle bracket, where it continues to sit today

Haagse groei versus Leidse krimp. Een vergelijking van de ruimtelijke ontwikkelingen in twee Hollandse steden tussen 1700 en 1870

After the economic prosperity of the Golden Age, the Netherlands entered a period of stagnation and decline, which lasted roughly from 1700 to 1850. During this period the city of Leiden saw its population shrink dramatically from some 53,000 inhabitants to around 36,000. The Hague, by contrast, experienced strong growth, from 30,000 to 52,000 inhabitants. This article compares spatial developments in these two northern Dutch cities based on development maps generated by a detailed analysis of historical city street maps. Such visual documentation of urban spatial changes in this period is still an infrequently used method. A comparison of the unique growth with the strong decline during three successive time periods, serves to highlight the spatial effects of both phenomena. 1700–1750/60 In 1700, the size of both cities within their outer defensive canals was much the same, but Leiden, thanks to a flourishing textile industry in the seventeenth century, was much more densely populated and had around twice as many inhabitants and houses as The Hague. In the administrative capital of The Hague, where the large number of wealthy citizens prompted an influx of servants, densification is most apparent within the canal ring. In Leiden, the stagnation of both the economy and the population meant that spatial change was minimal. In 1750 The Hague had around 35,000 inhabitants, almost as many as Leiden had in 1760, when its population stood at around 37,000. 1750/60–1830 Once again there is very little new construction to be seen in Leiden; instead there are many new open areas caused by demolition and the gunpowder ship disaster of 1807. In The Hague there is some new construction but much less than during the previous period. In both cities the largest new structure is an army barracks. The court capital filled in more canals and excavated a section of the Scheveningen Canal. In Leiden the ramparts lost their defensive function whereupon they were partially transformed into a park. By the end of this period, The Hague had 56,105 inhabitants, some 16,000 more than Leiden, but it still had a more open character. 1830–1870 The Hague underwent considerable densification inside the canal ring as well as extensions north and south of the city. The number of new tenements built on inner yards in The Hague can give a distorted impression, as can the number of demolished buildings in Leiden, because the 1870 maps were much more detailed. In Leiden the advent of new factories prompted new construction on the former city walls. The Hague, too, became a major industrial player, while continuing to profit from its function as the centre of government. In 1870, The Hague had almost twoand-a-half times as many inhabitants as Leiden (92,000 versus 39,000), but within the canal girdle Leiden was still more densely built up. Between 1700 and 1870, The Hague developed into one of the Netherlands’ biggest cities, which it still is. Leiden plummeted from second place to the middle bracket, where it continues to sit today

Nest tree use by southern flying squirrels in fragmented Midwestern landscapes

Southern flying squirrels (Glaucomys volans; SFS) nest in naturally formed cavities in snags and hardwoods found in mature, oak (Quercus spp.)–hickory (Carya spp.) forests. Intensive forest fragmentation of the Midwest United States limits the number of available nesting trees. We quantified annual nest‐site selection patterns by southern flying squirrels across fragmented landscapes of west‐central Illinois, USA. We used radiotelemetry to measure nest‐tree use by 55 SFS (30 males, 25 females) captured during 2014–2016. Of 105 nest trees used by SFS, live trees and snags comprised 75% and 25%, respectively. Probability of diurnal nest‐tree use increased 1.08/1.00‐cm increase in diameter‐breast‐height and by 1.50/1‐unit increase in the number of overstory mast trees between random and nest‐tree habitat areas (i.e., 300‐m2 circular plots). Similarly, probability of diurnal nest‐tree use increased 1.29/1‐unit increase in the number of snags between random and nest‐tree habitat areas. Our results revealed no intersexual differences in patterns of nest‐site selection, which may reflect the tendency for SFS to compensate for reduced availability of key structural attributes (i.e., snags, overstory trees) across fragmented forests by exhibiting similar intersexual patterns of nest‐tree use. Use of natural cavities for denning is encouraging, but also underscores the importance of unharvested oak–hickory forests in contributing essential habitat to SFS populations in fragmented Midwestern landscapes

In vivo sentinel lymph node identification using fluorescent tracer imaging in colon cancer:A systematic review and meta-analysis

Introduction: The use of fluorescence might improve the performance of the sentinel lymph node procedure in patients with colon cancer. This systematic review was conducted to gain insight in the performance and applicability of the sentinel lymph node procedure using fluorescence. Method: A systematic literature search was performed. Databases were searched for prospective studies concerning sentinel node identification using fluorescence in colon cancer. Detection rate, accuracy rate and sensitivity of the sentinel lymph node procedure were calculated for early stage (T1-T2) and more invasive (T3-T4) tumours. Results: Analyses of five included studies showed for respectively T3-T4 and T1-T2 tumours a detection rate of 90 % and 91 %, an accuracy rate of 77 % and 98 %, and a sensitivity of 30 % and 80 %. Conclusion: The sentinel lymph node procedure using fluorescence in early stage (T1-T2) colon cancer seems to be promising. Larger cohorts are necessary to confirm these results