Occlusal pattern of cheek teeth in extant Spermophilus: A new approach to the identification of species

Discrete characters of the occlusal surface (additional cusps) have been studied to elaborate a new approach to the identification of the Ground Squirrel species Spermophilus odessanus, S. suslicus, S. pygmaeus, S. citellus, and S. xanthoprymnus. Data on the presence/absence of the additional cusps have been represented as star plots and, in addition, have been studied using discriminant function analysis. The species‐specific sets of the characters (patterns of bunodonty) have been revealed and are of high diagnostic value. The Citellus‐set is defined by the presence of mesostyles and the rareness of the metastylids, paraconules and metaconules, hypostyles and protostyles. The Pygmaeus‐set is characterized by the presence of additional cusps in the lower cheek teeth. The Odessanus‐oriented set is found in the Spermophilus pygmaeus, S. odessanus, and S. suslicus. The relatively high frequency of additional cusps of the metaloph and the paraloph is characteristic for this set. The Plesiomorphic‐set (characters shared by all the studied species and for this reason regarded herein as ancestral) is found in S. xanthoprymnus. The patterns of bunodonty serve as diagnostic criteria only as a whole: the shape of a star plot (relations among the character frequencies), rather than certain character values, is indicative. An optimal level of identification of species is possible based on the combination of the discrete characters mentioned and on the size parameters of the third upper molar. The occlusal sets are intended to remain stable during the time of species existence and seem to correspond to trends in specialization. The functional meaning of the sets can be explained by the dependence between the presence/absence of the discrete characters and the shape of the crown and its main lophs. Each pattern is likely to correspond to a trophic niche, and this niche corresponds to the species. J. Morphol. 277:814–825, 2016. © 2016 Wiley Periodicals, Inc.     

The effect of temperature on conduction velocity in human muscle fibers

The effects of variation of intramuscular temperature (T) on conduction velocity (CV) of the action potential along single human muscle fibers of the biceps brachii was studied in situ in 15 normal volunteers (mean age 39 years, range 21–62 years). Cooling was obtained by direct application of ice over a rectangular skin region including the stimulating and recording area. The intramuscular T was monitored by a needle thermocouple (copperconstantane). In all the 24 muscle fibers studied, a linear relationship was observed between CV and T. The slopes of the regression lines, ranging between 0.190 and 0.079 m/s, were positively correlated with the starting CV at 36°C ranging between 2.2 and 5.2 m/s. If conduction changes are expressed as a percentage of the basal CV at 36°C, the CV/T coefficient is the same for all the fibers and independent of the individual CV: 3.4% of CV/°C.     

Modulation of DNA synthesis in aortic smooth muscle cells by dinitrotoluenes

Studies were conducted to determine if in vivo exposure to dinitrotoluenes (DNT), which is associated with circulatory disorders of atherosclerotic etiology in humans, is associated with alterations of vascular smooth muscle cells (SMC) consistent with the atherogenic process. Sprague-Dawley rats (150-180 g) were injected IP for 5 days/week for 8 weeks with 2,4- or 2,6-DNT (0.5, 5, or 10 mg/kg) or medium chain triglyceride (MCT) oil. Histopathologic evaluation of aortae from animals exposed to either isomer showed dysplasia and rearrangement of SMC at all doses tested. Reduced ³H-thymidine incorporation was observed in primary cultures of aortic SMC from DNT-exposed animals relative to vehicle controls. This inhibitory response was maintained for up to two passages in culture after which a significant increase in thymidine incorporation was observed. Exposure of SMC from naive animals to DNT in vitro (1–100 µM) did not alter the extent of thymidine incorporation in cycling or growth-arrested cultures. In contrast, exposure to 2,4- or 2,6-diaminotoluene (DAT) (1–100 µM), carcinogens which share toxic metabolic intermediates in common with DNT, inhibited replicative DNA synthesis and stimulated unscheduled DNA synthesis in cycling and growth-arrested cultures of SMC, respectively. Our results suggest that modulation of DNA synthesis in aortic SMC by DNT metabolites generated in vivo contribute to the development of vascular lesions.Abbreviation DAT diaminotuluene - tDNT technical grade dinitrotoluene - DNT dinitrotoluenes - HU hydroxyurea - IP intraperitoneal - LDH lactate dehydrogenase - MCT oil medium chain triglyceride - NPTC non-protein thiol content - RDS replicative DNA synthesis - SEM standard error of the mean - SMC smooth muscle cells - UDS unscheduled DNA synthesis     

Migration of myogenic cells in the rat extensor digitorum longus muscle studied with a split autograft model

Summary The ability of myogenic cells to migrate perpendicular to the long axis of freely autografted muscles was examined. Rat extensor digitorum longus muscles were divided, and one half was devitalized by repeated freezing in liquid nitrogen while the other half was kept viable in physiologic saline. The halves were reunited with sutures and grafted back into the original muscle bed. At intervals between 5 and 25 days the grafts were removed and examined histologically for the presence of myotubes within the devitalized region. Myotubes were first seen in the devitalized half 10 days postgrafting with the maximum number of myotubes observed after 12 to 15 days. These results indicate that myogenic cells are capable of migration perpendicular to the long axis of the muscle fibers in an autograft.     

Computational method for the real-time calculation of the full-body muscle load distribution

A method is described for minimising a quadratic function subject to equality and inequality constraints. This approach is applicable to solving the full-body muscle load distribution problem and calculating joint contact loads. It has been found that this approach can provide the solution on modest computing facilities and in significantly less time than using active set and interior point quadratic programming techniques. Hence the approach is suitable for providing real-time feedback to subjects undergoing biomechanical analysis of muscle, skeletal and joint loadings.     

Association between blood cadmium level and bone mineral density reduction modified by renal function in young and middle-aged men

The association between cadmium exposure and bone mineral density (BMD) has not been well studied in young and middle-aged men. This study examined the relationship between the level of blood Cd (BCd) and BMD in a young to middle-aged representative male population while considering renal function. Using data from the 4th Korea National Health and Nutrition Examination Survey, 2008–2009, 1275 adult men aged 20–64 years were analyzed. BCd was measured by atomic absorption spectrophotometry and renal function was assessed by the estimated glomerular filtration rate (eGFR) with CKD-EPI formula. The risk of lower bone density was increased according to the increase in BCd levels after adjusting for eGFR and covariates, in which a significant interaction between BCd and eGFR existed. Significant negative associations between BCd and BMD were found: beta (p-value) were −0.03 (0.02), −0.04 (0.004) and −0.03 (0.04) in total femur, lumbar spine and femoral neck, respectively, which were limited to the people with eGFR ≤ lower 25%. Although, a causal relationship could not be determined because of a cross-sectional design in the present study, the results suggest low level Cd toxicity to bone via low eGFR and that measures to reduce environmental Cd exposure may be helpful to prevent bone loss in men.     

7,9-Diaryl-1,6,8-trioxaspiro[4.5]dec-3-en-2-ones: Readily accessible and highly potent anticancer compounds

7,9-Diaryl-1,6,8-trioxaspiro[4.5]dec-3-en-2-ones are a recently described group of spirocyclic butenolides that can be generated rapidly and as a single diastereomer through a cascade process between γ-hydroxybutenolides and aromatic aldehydes. The following outlines our findings that these spirocycles are potently cytotoxic and have a dramatic structure–function profile that provides excellent insight into the structural features required for this potency.