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41.
Intra-arcadal mesiodistal and buccolingual tooth size correlations were evaluated in a sample of 125 caucasoids with ideal
occlusion. Dental dimensions were corrected for arcade mength (as a measure of jaw size) by a series of regression analyses
of each mesiodistal dimension on the sum of the mesiodistal dimensions within each arcade. Regression coefficients of tooth
dimension on arcade length were calculated to gain an insight into the dimensional sensitivity of individual teeth to arcade
length variation. The data presented here suggest a strong association between arcadal length (jaw size) dependence, and the
dimensional stability of individual teeth. When corrected for arcade length, a definite pattern of tooth size correlation
emerges: postcanine maxillary and mandibular teeth are negatively correlated to the anterior teeth and are positively correlated
to one another. The hypothesis is developed that anterior and postcanine teeth should be viewed as two separate and negatively
size-correlated units, beyond the boundaries of the four morphological tooth classes. Recognition of this basic dichotomous
size arrangement within each jaw allows for a reassessment of some of the problems associated with hominid dental evolution. 相似文献
42.
The present investigation assesses a number of explanations for the patterns of variability in dental dimensions. Coefficients of variation were calculated for mesiodistal and buccolingual diameters in a sample of 105 Papio ursinus crania (52 male, 53 female). Variability profiles consisting of arrays of values of coefficients of variation were evaluated by means of Friedman's two-way analysis of variance and Kendall's coefficient of concordance. Although molar teeth were found to be the most dimensionally stable, our results failed to support either the morphogenetic field theory or the occlusal complexity hypothesis. The data presented here are generally supportive of Pengilly's phenotypic complexity theory. However, speciesspecific clustering patterns found in our regressions of dimensional variability on mean tooth size suggest that differences in variability levels might be related to differences in selective pressures. 相似文献
43.
P H Groeneveld G Koopman N van Rooijen 《Virchows Archiv. B, Cell pathology including molecular pathology》1985,49(2):183-193
The aim of the present study was to compare the effects of LPS on the cellular composition of the splenic white pulp in responder C3H/He and non-responder C3H/HeJ mice. The present results show that an intravenous injection of LPS in C3H/He mice results in a number of prominent changes in the histology of the spleen, but none of these histological changes could be demonstrated in the unresponsive C3H/HeJ mice. However, the present study shows that LPS administration resulted in the disappearance of previously trapped immune complexes from the follicles in both responder C3H/He and non-responder C3H/HeJ mice. The significance of this phenomenon is discussed. The localization of intravenously injected LPS in both mouse strains was compared using an immunoperoxidase technique. Most of the injected LPS was taken up by marginal zone macrophages at 2 h after administration. No major differences could be detected in the localization pattern of LPS between C3H/He and C3H/HeJ mice. The present results support the suggestion that the genetically based unresponsiveness of C3H/HeJ mice could be due to an intracellular defect in their response to LPS. 相似文献
44.
JC. Brisset F. Gazeau C. Corot N. Nighoghossian Y. Berthezène E. Canet-Soulas M. Wiart 《IRBM》2018,39(2):93-102
Background
Inflammation is a share process in atherosclerosis and stroke and is thought to be a key player in the evolution of these diseases. Ten years ago, inflammation imaging with magnetic resonance imaging (MRI) was considered very promising for both pre-clinical and clinical studies of atherosclerosis and stroke.Contribution
We report here contributions to the field of inflammation imaging with USPIO-enhanced MRI. The goal was to investigate the life cycle of USPIOs in the body, and how the MRI signal has been impacted during their bio-interactions and bioprocessing. Those mechanisms were applied to pre-clinical longitudinal studies of inflammation in atherosclerosis and at the acute stage of ischemic stroke thus allowing the monitoring of treatment effects.Conclusion
This review presents the contribution of the collaborative research project under the “TecSan” grant from the French Research Agency (ANR) as well as pre-clinical and clinical perspectives of USPIO's inflammation MRI in atherosclerosis and stroke. 相似文献45.
Nonneutral evolution of tandem repeats in the mitochondrial DNA control region of lagomorphs 总被引:7,自引:0,他引:7
Casane D; Dennebouy N; de Rochambeau H; Mounolou JC; Monnerot M 《Molecular biology and evolution》1997,14(8):779-789
The mitochondrial DNA of the European rabbit (Oryctolagus cuniculus)
contains a tandem array of 153-bp repeats in the vicinity of the
replication origin of the H-stand. Variation among molecules in the number
of these repeats results in inter- and intraindividual length polymorphism
(heteroplasmy). Generally, in an individual, one predominant molecular type
is observed, the others representing a low percentage of the mtDNA content.
At the tissue level, we observe a particular distribution of this
polymorphism in the gonads compared with liver, kidneys, or brain, implying
a relationship between the differentiation status of the cells and the
types of new mtDNA molecules which appear and accumulate during lifetime.
Similar tandem repeats were also found in the mtDNA noncoding region of
European hares (Lepus europaeus), a cottontail (Sylvilagus floridanus), and
a pika (Ochotona rufescens). The lengths and the sequences of these units
evolve rapidly and in a concerted way, but the number of repeats is
maintained in a narrow range, and an internal 20-bp segment is highly
conserved. Constraints restrict the evolution of the primary sequence of
these repeated units, the number of which is probably controlled by a
stabilizing selection.
相似文献
46.
José C. Ramalho Thijs L. Pons Henri W. Groeneveld M. Antonieta Nunes 《Physiologia plantarum》1997,101(1):229-239
It is known that the coffee (Coffea arabica L.) plant which is originally from shade habitats would have a limited ability to grow under full sun. Previous work has shown that nitrogen fertilisation can reduce the leaf damage when the plants are exposed to high light intensities during several days. In the present work we aimed to study the effects of the high irradiance during the first hours and evaluate the positive contribution of nitrogen fertilisation in the case of short-term exposure to strong light. Young plants (1.5–2 years old) grown in 1.5 kg of a mixed soil were supplemented with a nutrient solution containing 15 mM nitrogen in the form of NH4NO3, every 7 days (2N treatment), 15 days (1N treatment) and 45 days (0N treatment). Top mature leaves were exposed to a photosynthetic photon flux density of 1 500 μmol m?2 s?1 for a maximal period of 8 h, and changes in photosynthesis and pigment composition were monitored along the period of high light exposure. Photosynthetic capacity, leaf conductance to water vapour, electron transport capacity and maximum carboxylation activity, as well as some leaf fluorescence parameters (minimal fluorescence, photochemical efficiency of PSII and quantum yield of photosynthetic electron transport) were reduced by the stress, with a generally stronger impact observed in the 0N plants. The photochemical quenching was affected only in the 0N plants, while the non-photochemical quenching increased in 2N plants but decreased in the 0N ones. The results showed that 2N plants presented a better initial status of the photosynthetic parameters and of the content of photoprotective pigments. Those plants showed ability to trigger some protective mechanisms, as observed by the tendency to increase the xanthophyll pool content, specially in zeaxanthin and in non-photochemical quenching. Also, protein content presented a tendency to increase after 1.5 h, which was maintained until the end of the high light period. We conclude that nitrogen availability is a key factor in the acclimation process to high light. 相似文献
47.
Jan R Leemreis Amanda M G Versteilen Pieter Sipkema A B Johan Groeneveld René J P Musters 《Cytometry. Part A》2006,69(9):973-978
BACKGROUND: Damaged and/or dysfunctional microvascular endothelium has been implicated in the pathogenesis of ischemic acute renal failure (ARF). Rapidly occurring changes in the endothelial F-actin cytoskeleton as observed in vitro might be responsible, but have been proven difficult to measure accurately in situ. Therefore, the purpose of this study was to examine several methods of digital image analysis in order to quantify the alterations of endothelial F-actin after renal ischemia and reperfusion (I/R), and to relate these to deterioration of renal function. METHODS: Frozen sections of Sham and I/R rat kidneys were fixed in 4% formaldehyde and stained with rhodamine-phallo?din. Microvascular structures were captured using a 3i Marianastrade mark digital imaging fluorescence microscope workstation. Images were analyzed using 3i SlideBooktrade mark software, employing several masking techniques and line-scans. RESULTS: Digital image analysis demonstrated a decrease in the mean intensity of rhodamine-phallo?din fluorescence after I/R from 1030 +/- 187 to 735 +/- 121 a.u. (arbitrary units, mean +/- SD, n = 7). The number of F-actin fragments per pixel increased from (15.8 +/- 4.9) x 10(-5) to (20.7 +/- 3.5) x 10(-5) (n = 7), indicating cytoskeletal fragmentation. In addition, line-scan analysis demonstrated a disturbed spatial orientation of the F-actin cytoskeleton after I/R. Finally, the loss of F-actin correlated with a rise in plasma creatinine. CONCLUSIONS: The methods of digital image analysis described in the present study demonstrate that renal I/R induces profound changes in the F-actin cytoskeletal structure of microvascular endothelial cells, implicating an injured and dysfunctional microvascular endothelium, which may contribute to acute renal failure (ARF). 相似文献
48.
Distinguishing morphologically cryptic taxa, by definition, requires genetic data such as DNA sequences. However, DNA sequences may not be obtained easily for taxa from remote sites. Here we provide the details of a high-resolution melt-curve-based method using taxon-specific primers that can distinguish two taxa of Adélie penguins, and that will be usable in Antarctica when combined with some of the newly developed field-deployable thermal cyclers. We suggest that the wider adoption of field-deployable polymerase-chain-reaction-based techniques will enable faster assignation of haplotype to individuals in situ, and so allow the targeting of observations and sample collection to specimens relevant to the research question. Targeting individuals will also reduce the need to repeatedly handle animals and reduce the time and travel required to complete field work. 相似文献
49.
50.
Rupert CM Jones Maria Dickson-Spillmann Martin JC Mather Dawn Marks Bryanie S Shackell 《Respiratory research》2008,9(1):62