Hindlimb unweighting (HU) leads to capillary regression in skeletal muscle. However, the molecular mechanism(s) remains to be elucidated. To gain insight into the regulation of this process, we investigated gene expression of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), angiopoietin, and their receptors in the atrophied muscle induced by HU. The hindlimbs of mice were unweighted by tail-suspension and then the gastrocnemius muscles were isolated after 10 days. To assess the capillary distribution, the capillary endothelium in frozen transverse sections was identified by staining for alkaline phosphatase. The mRNA levels were analyzed using a real-time reverse transcription-polymerase chain reaction. After 10 days of HU, the number of capillaries around a muscle fiber was significantly decreased by 19.5 %, suggesting that capillary regression appears to occur. The expression of HIF-1α was significantly down-regulated after 10 days of HU. The expression of VEGF remained unchanged, whereas those of Flt-1, KDR/Flk-1, and neuropilin-1 were significantly down-regulated, suggesting that VEGF signaling through these receptors would be attenuated. The expression of angiopoietin-1, and -2, as well as their receptor, Tie-2 were also significantly down-regulated, suggesting that angiopoietin-1 signaling through Tie-2 would be attenuated. These findings suggest that alterations in expression of VEGF, angiopoietins, and their receptors may be associated with capillary regression after HU., A. Wagatsuma., and Obsahuje biblografii a bibliografické odkazy
Už 4,5 miliónu let nás vyvýšená hlava, vpřímená postava a bipední lokomoce odlišuje od většiny savců. Tento článek zvažuje důvody pro tuto evoluční změnu (např. tlak prostředí), její známé přednosti, ale také rizika. Bipední hominin byl ve srovnání se zvířecími predátory i kořistí pomalejší, jeho chrup jako zbraň či nástroj byl stále méně použitelný a tekutiny musel přenášet. Ale vzpřímení postavy uvolnilo lidskou ruku pro produkci artefaktů - nástrojů. Technologie, která původně umožnila přežití, v průběhu evoluce stimuluje strmý demografický růst a ten zpětně vyžaduje další technologické i organizační inovace. Dnes už by bez nich lidé jako savci střední velikosti s velkou spotřebou a produkcí odpadu nemohli v počtu řádově miliard existovat., For 4.5 million years, our raised head, upright stature and bipedal locomotion have distinguished us from the majority of other mammals. The paper evaluates the reasons for this evolutionary change (such as environmental pressure), its advantages but also risks. Compared to animal predators and prey, the bipedal hominid was slower and his dentition less usable as a tool or weapon. However, the raised stature made the hand free for production of artifacts - tools. Technology, which enabled survival at the beginning, stimulated steep demographic growth during later evolution., and Jiří Svoboda.