Search

Laboratory animal models play an important role in the study of human diseases. Using appropriate animals is critical not only for basic research but also for the development of therapeutics and diagnostic tools. Rabbits are widely used for the study of human atherosclerosis. Because rabbits have a unique feature of lipoprotein metabolism (like humans but unlike rodents) and are sensitive to a cholesterol diet, rabbit models have not only provided many insights into the pathogenesis and development of human atherosclerosis but also made a great contribution to translational research. In fact, rabbit was the first animal model used for studying human atherosclerosis, more than a century ago. Currently, three types of rabbit model are commonly used for the study of human atherosclerosis and lipid metabolism: (1) cholesterol-fed rabbits, (2) Watanabe heritable hyperlipidemic rabbits, analogous to human familial hypercholesterolemia due to genetic deficiency of LDL receptors, and (3) genetically modified (transgenic and knock-out) rabbits. Despite their importance, compared with the mouse, the most widely used laboratory animal model nowadays, the use of rabbit models is still limited. In this review, we focus on the features of rabbit lipoprotein metabolism and pathology of atherosclerotic lesions that make it the optimal model for human atherosclerotic disease, especially for the translational medicine. For the sake of clarity, the review is not an attempt to be completely inclusive, but instead attempts to summarize substantial information concisely and provide a guideline for experiments using rabbits.

In this study, we created LDL receptor (LDLr) defective (WHHL) transgenic rabbits expressing human apo[a] to examine whether LDLr mediates the Lp[a] clearance from the plasma. By crossbreeding WHHL rabbits with human apo[a] transgenic rabbits, we obtained two groups of human apo[a] transgenic rabbits with defective LDLr functions: apo[a](1/0) WHHL heterozygous (LDLr(+/-) and apo[a](+/0) WHHL homozygous (LDLr(-/-) rabbits. The lipid and lipoprotein levels of human apo[a] WHHL rabbits were compared to those of human apo[a] transgenic rabbits with normal LDLr functions (LDLr(+/+). The apo[a] production rate was evaluated by analyzing apo[a] mRNA expression in the liver, the major site for apo[a] synthesis in transgenic rabbits. We found that pre-beta lipoproteins were markedly increased accompanied by a 2-fold increase in the plasma Lp[a] in apo[a](+/0)/LDLr(+/-) rabbits and a 4.2-fold increase in apo[a](+/0)/LDLr(-/-) rabbits compared with that in apo[a](+/0) rabbits with normal LDLr function. In apo[a](+/0)/LDLr(-/-) rabbits, there was a marked increase in plasma total cholesterol and triglycerides, as was found in their counterpart non-transgenic WHHL rabbits. Northern blot analysis revealed that hepatic apo[a] expression in WHHL transgenic rabbits was similar to that in LDLr(+/+) transgenic rabbits, suggesting the accumulation of plasma Lp[a] in WHHL transgenic rabbits was not due to increased apo[a] synthesis. In conclusion, absence of a functional LDLr leads to a marked accumulation of plasma Lp[a] in human apo[a] transgenic WHHL rabbits and LDLr may participate in the catabolism of Lp[a] in rabbits.

The central part of the Hidaka Metamorphic Belt (HMB) is divided into six metamorphic zones : lower-biotite, upper-biotite, garnet, sillimanite-muscovite, garnet-cordierite and orthopyroxene zones. A significant temperature gap with lithological contrast is recognized between the sillimanite-muscovite and garnet-cordierite zones. In the garnet-cordierite and orthopyroxene zones, marked prograde zoning profiles occur in garnets in amphibolites. Geothermometry and diffusion modeling for the zoning profiles of these garnets suggest that the rims were formed under upper amphibolite-facies and granulite-facies conditions, with a brief and rapid increase in temperature at peak metamorphism. The latest pulse of SHRIMP zircon dating of granulite (Early Miocene) in the Hidakahorobetsu River area may explain the granulite-facies metamorphism recorded the garnet rims, which occurred just before the uplift episode indicated by K-Ar ages.

^Ar-^Ar ages were obtained for two granitic rocks from the Dry Valleys region of South Victoria Land, Antarctica. One sample (biotite-rich fraction) of foliated granitoid gave three age increments of 491Ma, 502Ma and 506Ma, with K/Ca ratios suggesting influence of cooling ages of biotite (younger age) and that of hornblende (older age). Granitoid emplacement is thought to have been before 506Ma, with cooling from biotite closure temperatures about 490Ma. A sample of unfoliated granitoid gave ages of 467-496Ma. The similarity of ages determined for both "pre-tectonic" and "post-tectonic" samples indicate closure of isotopic systems around 490Ma due to regional uplift/exhumation, rather than actual emplacement ages of individual plutons in South Victoria Land.

Natural levels of solar UVR were shown to break and alter the spiral structure of Arthrospira (Spirulina) platensis (Nordst.) Gomont during winter. However, this phenomenon was not observed during summer at temperatures of 30C. Since little has been documented on the interactive effects of solar UV radiation (UVR; 280?400 nm) and temperature on cyanobacteria, the morphology, photosynthesis, and DNA damage of A. platensis were examined using two radiation treatments (PAR [400?700 nm] and PAB [PAR + UV-A + UV-B: 280?700]), three temperatures (15, 22, and 30C), and three biomassconcentrations (100, 160, and 240 mg dwt [dry weight] Æ L)1). UVR caused a breakage of the spiral structure at 15C and 22C, but not at 30C. High PAR levels also induced a significant breakage at 15C and 22C, but only at low biomass densities, and to lesser extent when compared with the PAB treatment. A. platensis was able to alter its spiral structure by increasing helix tightness at the highest temperature tested. The photochemical efficiencywas depressed to undetectable levels at 15C but was relatively high at 30C even under the treatment with UVR in 8 h. At 30C, UVR led to 93%?97% less DNA damage when compared with 15C after 8 h of exposure. UV-absorbing compounds were determined as negligible at all light and temperature combinations. The possible mechanisms for the temperature-dependent effects of UVR on this organism are discussed in this paper. Fil: Gao, Kunshan. Shantou University; China. Xiamen University; China Fil: Li, Ping. Shantou University; China Fil: Watanabe, Teruo. No especifíca; Fil: Helbling, Eduardo Walter. Shantou University; China. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación Playa Unión. Estación de Fotobiología Playa Unión; Argentina

Recently, Chung et al. have reported the detailed clinicopathological features of an extremely rare case sharing similar histopathological characteristics with fibroadenomas, phyllodes tumours, intraductal papillomas or ductal adenomas, given the name of intraductal fibroadenomatosis, as an unusual variant of intracanalicular fibroadenoma. Herein we demonstrated a very unusual case of intraductal fibroadenoma of the breast with admixture of components of intracanalicular type fibroadenoma or benign phyllodes tumour and a smaller amount of intraductal papilloma, occupying the one duct and some adjacent ductules, presenting as a well-demarcated nodule.