Topography and structure of the stylohyoid muscle in mammals

Topography and structure of the musculus stylohyoideus (MSH) have been studied in 78 species of Mammalia from 12 orders. The muscle in question has specific peculiarities not only in its position and fixation, but also in a great variability of its structure. The MSH is not revealed in Philander opossum, Lagostrophus fasciatus, guinea pig, Meriones eversmanni, Rhombomys opimus, Nyctereutes procyonoides, Thos aureus, Mastelidae. Various pathways of development and different functional loading define existence of several modifications of the MSH: a) the medial part of the muscle develops (Didelphys, Rodentia, Insectivora, Proboscidea, Dama dama, Capreolus capreolus; b) the lateral part of the musculus develops (Lagomorpha, Canis lupus, Ursidae, Felidae, Pinnipedia, Cavicornia); c) both parts of the musculus develop, determining position of the m. digastricus between these two parts (Alces alces, Pseudaxis sica, Cervus elaphus, Macaca rhesus, Erythrocebus patas, Perissodastyla).     

Electrophysiologic, morphometric and histocytochemical characteristics of frog sartorius muscle fibers]

Three groups of muscle fibers (dark, light, and intermediate) were revealed in the fibers of the frog sartorius muscle in examination of the succinate dehydrogenase (SDH) activity. There was revealed a reverse relationship between the diameter of the muscle fibers an the SDH activity in them. The external surface of sartorius muscle is chiefly represented by dark muscle fibers, whereas the internal one--by light ones. Microelectrode study demonstrated that the fibers of the external surface were characterized, in comparison with those of the internal one, by lesser action potentials, prolonged trace negative potential, low quant composition of the end plate potentials, high amplitude and low frequency of the end plate miniature potentials. Analysis of the data obtained demonstrated definite interrelationship between the histochemical profile of the muscle fibers of the frog sartorius muscle and their electrophysiological characteristics.     

Turnover of pegeon breast muscle pyruvate dehydrogenase complex.

The pigeon breast muscle pyruvate dehydrogenase complex was resolved into three component enzymes: lipoate acetyltransferase, pyruvate dehydrogenase, and lipoamide dehydrogenase. The antibodies against each component enzyme were prepared. All of the antibodies against component enzymes precipitated the pyruvate dehydrogenase complex. The enzyme complex was recovered as the immunoprecipitate from the extract of breast muscle of a pigeon that had received a single injection of L-[4,5-3H]leucine. The immunoprecipitate was separated into each component enzyme by SDS-polyacrylamide gel electrophoresis. The relative isotopic leucine incorporations per mg of protein into each component enzyme 4 h after the injection were 1.0 : 0.9 : 1.4 : 2.7 for lipoate acetyltransferase, alpha- and beta-subunit of pyruvate dehydrogenase, and lipoamide dehydrogenase, respectively. The half-lives of lipoate acetyltransferase, alpha- and beta-subunit of pyruvate dehydrogenase, and lipoamide dehydrogenase were 7.7, 2.5, 2.6, and 1.8 days, respectively. These results indicate that the component enzymes of the pyruvate dehydrogenase complex were synthesized and degraded at different rates.     

Electrophysiologic principles of radiofrequency lesion making.

Understanding of the electrophysiologic principles of radiofrequency lesion making is necessary to ensure reliable results in surgical procedures using this technique. A radiofrequency lesion is produced by tissue electrocoagulation. Its method of formation and factors affecting heat generation and loss are discussed. Guidelines for making radiofrequency lesions, based on electrophysiologic principles are outlined.     

Partial purification and identification of cardiodepressant factor from the posterior pituitary lobe in rats.

It has been demonstrated previously that the cardiodepressant activity is present in the bovine hypothalamic extract and in the medium incubating the rat's posterior pituitary lobe "in situ". In this study medium incubating the posterior pituitary lobe was fractionated by a low pressure gel filtration procedure and the cardiodepressant fractions were pooled and further purified by the HPLC technique on C8 and TSK 3000 SW columns. It was shown, on the basis of mass spectrometry, that cardiodepressant activity is associated with substance(s) with molecular mass of about 500 d. Application of this fraction into the fluid used for incubation of isolated right auricle of the right heart atrium of a two-day-old rat, strongly decreased the frequency of spontaneous discharge of the pacemaker tissue.     

蟋蟀后肠纤维素降解细菌的分离与鉴定

近年来,具有农业、能源和环保价值的昆虫微生物种类和基因得到了开发,昆虫肠道微生物展示了其巨大的应用潜力,本研究旨在从蟋蟀后肠分离和鉴定纤维素降解细菌。首先采用羧甲基纤维素钠液体培养基对蟋蟀后肠中的微生物进行富集培养,然后使用羧甲基纤维素钠固体培养基分离和筛选单菌落,再通过16S rRNA测序对纤维素降解细菌进行分子鉴定,最后通过刚果红染色来进一步分析细菌降解纤维素的能力。从蟋蟀后肠中共分离出20株纤维素降解细菌,16S rRNA基因测序结果显示来自肠杆菌属(Enterobacter)9株,不动杆菌属(Acinetobacter)7株,克雷伯氏菌属(Klebsiella)2株,鞘氨醇杆菌属(Sphingobacterium)1株和葡萄球菌属(Staphylococcus)1株。刚果红染色试验结果显示,克雷伯氏菌属两株PDSCDXS_2B和8B,鞘氨醇杆菌属PDSCDXS_7C和不动杆菌属PDSCDXS_12C具有较高的纤维素降解能力。这是首次从蟋蟀后肠分离和筛选出来具有纤维素降解能力的细菌,为昆虫源纤维素降解细菌的研究提供了微生物资源。     

Where is the glycolytic complex? A critical evaluation of present data from muscle tissue

Associations between glycolytic enzymes and subcellular structures have been interpreted as presenting a novel mechanism of glycolytic control; reversible enzyme binding to subcellular structural components is believed to regulate enzyme activity in vivo through the formation of a multi-enzyme complex. However, three lines of evidence suggest that enzyme binding to cellular structures is not involved in the control of glycolysis. (i) Calculations of the distribution of glycolytic enzymes under the physiological cellular conditions of higher ionic strength and higher enzyme concentrations indicate that a large multi-enzyme complex would not exist. (ii) In many cases, binding to subcellular structures is accompanied by changes in enzyme kinetic parameters brought about by allosteric modification, but these changes often inhibit enzyme activity. (iii) In the case where formation of binary enzyme/enzyme complexes activates enzymes, the overall increase in flux through the enzyme reaction is negligible.     

ProCope--protein complex prediction and evaluation

SUMMARY: Recent advances in high-throughput technology have increased the quantity of available data on protein complexes and stimulated the development of many new prediction methods. In this article, we present ProCope, a Java software suite for the prediction and evaluation of protein complexes from affinity purification experiments which integrates the major methods for calculating interaction scores and predicting protein complexes published over the last years. Methods can be accessed via a graphical user interface, command line tools and a Java API. Using ProCope, existing algorithms can be applied quickly and reproducibly on new experimental results, individual steps of the different algorithms can be combined in new and innovative ways and new methods can be implemented and integrated in the existing prediction framework. AVAILABILITY: Source code and executables are available at http://www.bio.ifi.lmu.de/Complexes/ProCope/.     

Pulvina-lateralis posterior nucleus complex of mammals and the visual function

It is now well established that the lateral posterior-pulvinar (LP-P) complex of mammals is involved in visual processing. However, the actual function of these large nuclei of the thalamus remains unknown. In contrast to the nearby lateral geniculate nucleus, the LP-P complex does not receive any substantial direct projections from the retina. Its main visual inputs come from the mesencephalon and the neocortex. Most cells in the LP-P complex behave like cortical units. They are tuned to the orientation, direction, spatial and temporal frequencies of the visual stimulus. In addition, most units are binocular and sensitive to relative retinal disparity. Despite their multiple inputs, the LP-P complex cells form an homogeneous population and their overall properties do not reflect those of a given cortical or subcortical area. On the basis of its afferent and efferent connectivity, it has been proposed that the LP-P complex may serve as a relay of an extrageniculate ascendant pathway which originates from the superior colliculus, and/or provide another route for the geniculo-striate input to reach the extrastriate areas. Despite the fact that there is some electro-physiological evidence of such functions, it is now often suggested that the LP-P complex may integrate its multiple inputs and be involved in functions which go beyond those of a simple thalamic relay. Recent findings suggest that the LP-P complex might play a role in visual spatial attention.     

Isolated populations and complex disease gene identification

The utility of genetically isolated populations (population isolates) in the mapping and identification of genes is not only limited to the study of rare diseases; isolated populations also provide a useful resource for studies aimed at improved understanding of the biology underlying common diseases and their component traits. Well characterized human populations provide excellent study samples for many different genetic investigations, ranging from genome-wide association studies to the characterization of interactions between genes and the environment.     

Phosphorylation of an actin.tropomyosin.troponin complex from human skeletal muscle.

A human skeletal actin.tropomyosin.troponin complex was phosphorylated in the presence of [gamma-32 P]ATP, Mg2+, adenosine 3':5'-monophosphate (cyclic AMP) and cyclic AMP-dependent protein kinase (protein kinase). Phosphorylation was not observed when the actin complex was incubated in the absence of protein kinase or 1 microM cyclic AMP. In the presence of 10(-7) M Ca2+ and protein kinase 0.1 mole of [32P]phosphate per 196 000 g of protein was incorporated. This was two-fold higher than the [32P]phosphate content of a rabbit skeletal actin complex but two-fold lower than that of a bovine cardiac actin complex. At high Ca2+, 5.10(-5) M, little change in the phosphorylation of a human skeletal actin complex occurred. Phosphoserine and phosphothreonine were identified in the [32P]phosphorylated actin complex. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate showed that 60% of the label was associated with the tropomyosin binding component of troponin. The inhibitory component of troponin contained 16% of the bound [32P]phosphate. Increasing the Ca2+ concentration did not significantly decrease the [32P]phosphate content of the phosphorylated proteins in the actin complex. No change in the distribution of phosphoserine or phosphothreonine was observed. Half maximal calcium activation of the ATPase activity of reconstitute human skeletal actomyosin made with the [32P] phosphorylated human skeletal actin complex was the same as a reconstituted actomyosin made with an actin complex incubated in the absence of protein kinase at low or high Ca2+.     

Four-state models and regulation of contraction of smooth muscle. II. Properties of the solutions and identification.

We analyze the behavior and the identification problem of cyclic four-state models. We find that for any state, or a weighted combination of two states, there can be at most one maximum, or one minimum, and two inflection points. We obtain necessary conditions for overshoot and undershoot and give examples. We describe procedures to estimate all the rate constants and discuss certain experimental aspects of the identification problem. Finally, we give an example of identification by obtaining the 10 model parameters from experimental data on skinned fibers from smooth muscle. These results, in conjunction with the results of the previous paper, can help in testing four-state models of regulation of contraction of smooth muscle and of a variety of other physiological and biochemical phenomena.     

Laryngeal influences on breathing pattern and posterior cricoarytenoid muscle activity

Receptors responding to transmural pressure, airflow, and contraction of laryngeal muscles have been previously identified in the larynx. To assess the relative contribution of these three types of receptors to the reflex changes in breathing pattern and upper airway patency, we studied diaphragmatic (DIA) and posterior cricoarytenoid muscle (PCA) activity in anesthetized dogs during spontaneous breathing and occluded efforts with and without bypassing the larynx. Inspiratory duration (TI) was longer, mean inspiratory slope (peak DIA/TI) was lower, and PCA activity was greater with upper airway occlusion than with tracheal occlusion (larynx bypassed). Bilateral section of the superior laryngeal nerves eliminated these differences. When respiratory airflow was diverted from the tracheostomy to the upper airway the only change attributable to laryngeal afferents was an increase in PCA activity. These results confirm the importance of the superior laryngeal nerves in the regulation of breathing pattern and upper airway patency and suggest a prevalent role for laryngeal negative pressure receptors.     

Respiratory activity of posterior cricoarytenoid muscle and vocal cords in humans

We examined the respiratory activity of the posterior cricoarytenoid muscle (PCA) simultaneously with the movements of the vocal cords during tidal breathing and panting in four normal seated subjects. A bipolar electrode was constructed to record the surface electromyogram (EMG) of the PCA. The glottis was visualized with a fiberoptic bronchoscope, and the glottic image was recorded simultaneously with tidal volume and a digital time marker on video tape. During quiet breathing the integrated EMG signal (EPCA) showed consistent phasic variations in each subject. The inspiratory onset of EPCA in the four subjects preceded inspiratory flow by 170 +/- 80, 650 +/- 310, 130 +/- 80, and 130 +/- 90 ms (mean +/- SD), respectively. This lead time of the PCA was similar to that between the onset of glottic widening and inspiration in each subject. The proportion of each cycle during which EPCA increased (the duty cycle) was 31 +/- 3% (mean +/- SE), whereas the inspiratory portion of the respiratory cycle constituted 37 +/- 2% (mean +/- SE), respectively. The duty cycle of the PCA remained relatively constant in the same subject on different days. During panting at functional residual capacity, the EPCA increased to 142 +/- 11% of the peak activity recorded during the preceding control breaths. This was accompanied by a sustained increase in the glottic width to 91 +/- 9% of the peak value in the preceding breaths. These results confirm the role of the PCA as a principal abductor of the vocal cords and indicate a temporal relationship between PCA activation and the inspiratory phase of the respiratory cycle during tidal breathing in humans.     

The identification of myogenic cells in regenerating skeletal muscle. II. Early mammalian regenerates.

Most of the recent studies on skeletal muscle regeneration have used the criteria of cell shape and position as the primary means of identifying early presumptive myogenic elements or satellite cells. Studies of anuran muscle regeneration indicate, however, that macrophages can mimic early myogenic cells by adopting a fusiform shape and a sublaminar position during the initial stages of phagocytic invasion. The present study confirms these observations in injured mammalian muscle. Gastrocnemius muscle tissues from Sprague-Dawley rats were killed by lyophilization or repeated freezing and implanted subcutaneously to examine the cytology of the invading macrophages free from contamination by any endogenous myogenic cells. Within 2 days the implants are infiltrated by large numbers of fusiform macrophages. These cells form continuous cuffs around the degenerating myofibers but initially show little evidence of phagocytosis. They contain dense concentrations of free ribosomes but display few lysosomes, phagosomes, or pseudopodia. These distinctive phagocytic features do not appear until the macrophages penetrate the cores of the injured fibers and actually begin removal of the myofibrillar debris. These observations indicate that the criteria of cell shape and location cannot reliably distinguish between early mammalian macrophages and myogenic cells.