Light and electron microscopic studies on capillaries of the goat cardiac muscle with special reference to the topographical relationship between the vessels and Purkinje fibers

The capillaries of the cardiac muscle were investigated in the goat by means of light microscopy, transmission electron microscopy and scanning electron microscopy, and the following results were obtained. The capillaries of the working cardiac muscles were numerous, arranged mainly parallel to the long axis of muscle cells and formed dense elongated networks. On the contrary, those of the terminal Purkinje fibers were relatively few in number, oriented in various directions and formed loose and circularly meshed networks surrounding the fibers. Such findings were discussed in correlation with the physiology and functional morphology of various types of the cardiac muscle cells.     

The effect of sedimentation and microbial nitrogen regeneration in a plankton community: a simulation investigation

A computer simulation model was developed to investigate nitrogenfluxes associated with microbial interactions in plankton communities.A short time scale was used, appropriate to the build-up anddecline of phytoplankton blooms in temperate shelf waters aftera mixing or upwelling event. The model depicts a continuum ofevents, many of which have been observed in coastal, upwellingand oceanic systems, including two phytoplankton peaks correspondingto ‘new production’ and ‘regenerated production’.It predicts that nitrogen loss through sedimentation of phytoplanktonand faeces may result in a smaller bloom with a delayed onsetand prolonged duration. Microbial regeneration of nitrogen wasfound to be important in sustaining the middle stages of a phytoplanktonbloom, whereas micro- and meso-zooplankton regeneration occurredtowards the end of the bloom.     

Correlation between the bone mass of athletes and biochemical and genetic markers of bone tissue remodeling

The association of the polymorphism of the VDR, Col1a1, and CALCR genes with a form of osteoporosis frequently occurring as a consequence of intense physical exercise in athletes was studied. Biochemical parameters of bone remodeling and its neuroendocrine regulation, as well as the bone masses, of 22 amateur athletes were determined immediately before a strenuous nine-week training cycle (TC) and eight months later. The possible association of these factors with the polymorphism of the genes coding for bone tissue proteins was studied. Long-term intense physical training was found to be associated with a significant activation of bone tissue resorption accompanied by continued rapid synthesis. Nevertheless, and in spite of the strong activation of resorption caused by the TC, the athletes exhibited no osteoporosis (even eight months after the discontinuation of the TC); some of them, however, displayed an individual tendency to osteopenia. According to the results of genetic analysis, this was associated with the polymorphism of predisposition genes (genotype TT of the VDR gene and the functionally weakened s allele of the Col1a1 gene).     

Direct Comparisons of 2D and 3D Dental Microwear Proxies in Extant Herbivorous and Carnivorous Mammals

The analysis of dental microwear is commonly used by paleontologists and anthropologists to clarify the diets of extinct species, including herbivorous and carnivorous mammals. Currently, there are numerous methods employed to quantify dental microwear, varying in the types of microscopes used, magnifications, and the characterization of wear in both two dimensions and three dimensions. Results from dental microwear studies utilizing different methods are not directly comparable and human quantification of wear features (e.g., pits and scratches) introduces interobserver error, with higher error being produced by less experienced individuals. Dental microwear texture analysis (DMTA), which analyzes microwear features in three dimensions, alleviates some of the problems surrounding two-dimensional microwear methods by reducing observer bias. Here, we assess the accuracy and comparability within and between 2D and 3D dental microwear analyses in herbivorous and carnivorous mammals at the same magnification. Specifically, we compare observer-generated 2D microwear data from photosimulations of the identical scanned areas of DMTA in extant African bovids and carnivorans using a scanning white light confocal microscope at 100x magnification. Using this magnification, dental microwear features quantified in 2D were able to separate grazing and frugivorous bovids using scratch frequency; however, DMTA variables were better able to discriminate between disparate dietary niches in both carnivorous and herbivorous mammals. Further, results demonstrate significant interobserver differences in 2D microwear data, with the microwear index remaining the least variable between experienced observers, consistent with prior research. Overall, our results highlight the importance of reducing observer error and analyzing dental microwear in three dimensions in order to consistently interpret diets accurately.     

Changes in the size of the myocardial damaged area in postischemic reperfusion

The changes in the size of the myocardial injury area during reperfusion after the coronary occlusion-induced ischemia lasting 30 minutes are phasic in nature. Until 3.5 h the injured area increases and after 23.5 h relatively diminishes. After a more prolonged ischemia such manifestations are either unmarked or absent. Ischemia lasting from 30 min to 4 hours followed by reperfusion, as compared with ischemia of the same duration without reperfusion, normally gives rise to the formation of an area of injury, which is less or occasionally equal in size. The data obtained and reported indicate that in the area of coronary occlusion there are groups of cardiomyocytes that differ as regards the resistance to ischemia.     

Induction of electrogenic phosphate transport through the mitochondrial membrane by a thermostable cytoplasmic factor in hyperthyroidism

Addition of a thermostable cytoplasmic fraction leads to the uncoupling of oxidative phosphorylation of the mitochondria. In hyperthyrosis such an effect manifests itself more powerfully than in the control. Addition of the thermostable cytoplasmic fraction induces electrogenic phosphate transport via the mitochondrial membrane. In hyperthyrosis, the activity of the thermostable inducer of phosphate transport in the cytoplasm increases. The functioning of the phosphate cycle may be the cause of the uncoupling of oxidative phosphorylation of the mitochondria during the disease in question.     

Radioimmunoassay for beta-endorphin (1-18), a novel pituitary peptide derived from proopiomelanocortin

A specific radioimmunoassay was developed for beta-endorphin (1-18). The content of beta-endorphin (1-18) immunoreactivity in rat tissues was as follows: posterior pituitary 260 ng/fragment, anterior pituitary 1.46 ng/mg, hypothalamus 11.9 pg/mg. The levels were undetectable (less than 3 pg/mg) in extrahypothalamic brain, pancreas, small intestine, prostata and testis. Gel filtration and reverse-phase HPLC studies indicated that most of rat anterior pituitary immunoreactivity is due to native beta-endorphin (1-18), whereas the bulk of posterior pituitary immunoreactivity corresponds to more hydrophobic material, probably N-acetyl-beta-endorphin (1-18). Thus, beta-endorphin (1-18) is a quantitatively important novel pituitary peptide derived from proopiomelanocortin. The posterior pituitary is an especially rich source of (N-acetyl)-beta-endorphin (1-18).