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Query: UNIPROT:P06889 (Mol)
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Phylogenetic trees were constructed for 62 venom toxins of snakes of Proteroglyphae suborder using matrix method. The resulting tree from Minimum Spanning Tree-Cluster Analysis technique had the lowest "percent deviation" (8.55). The taxonomic relationship of these toxins agrees very well with zoological opinions. However, the appearance of the tree did not directly provide a plausible evolutionary model for the toxins. A model was derived from nodal ancestral sequence calculations, comparisons between intra- and intergenerical rates of amino acid change, and generally held ideas about protein evolution. According to the model, short neurotoxin is the ancient form of snake venom toxins. The courses of evolution leading to the present intraspecific homologous toxins are explained by gene duplication and allelomorphism.
J Mol Evol 1977 Nov 25
PMID:Molecular evolution of snake venom toxins. 59 23

Goodman et al.'s (1974) populous path algorithm for estimating hidden mutational change in protein evolution is designed to be used as an adjunct to the maximum parsimony method. When the algorithm is so used, the augmented maximum parsimony distances, far from being overestimates, are underestimates of the actual number of nucleotide substitutions which occur in Tateno and Nei's (1978) computer simulation by the Poisson process model, even when the simulation is carried out at two and a half times the sequence density. Although underestimates, our evidence shows that they are nevertheless more accurate than estimates obtained by a Poisson correction. In the maximum parsimony reconstruction, there is a bias towards overrepresenting the number of shared nucleotide identities between adjacent ancestral and descendant nodal sequences with the bias being stronger in those portions of the evolutionary tree sparser in sequence data. Because of this particular property of maximum parsimony reconstructed sequences, the conclusions of Tateno and Nei concerning the statistical properties of the populous path algorithm are invalid. We conclude that estimates of protein evolutionary rates by the maximum parsimony--populous path approach will become more accurate rather than less as larger numbers of closely related species are included in the analysis.
J Mol Evol 1978 May 12
PMID:On investigating the statistical properties of the populous path algorithm by computer simulation. Counterconclusions to those of Tateno and Nei. 66 Jun 64

In an attempt to understand better the directional differences in conduction velocity in the rabbit sinoatrial node, a possible conductive role of the abundant connective tissue surrounding the myocytes has been investigated. In particular, starting from the finding of communicating junctions between heart muscle cells and fibroblasts in tissue culture, heterologous gap junctions were searched for in thin sections of the rabbit sinoatrial node. Within and at the edge of nodal cell clusters, fibroblasts often show thin sheet-like extensions parallel to the surface of myocytes. In contrast to the intimately contacting myocytes, fibroblast extensions are kept separated from the myocytes by the basement membrane of the latter. Besides some rare undefined membrane appositions a single tiny gap junction-like structure was found between a fibroblast and a myocyte in a tissue area in which the calculated number of gap junctions between myocytes amounts from 1.10(4) to 3.10(4). Yet, fibroblasts are linked together regularly by small gap junctions containing a wider gap than the junctions between the myocytes (1.4 +/- 0.4 nm vs. 1.0 +/- 0.4 nm, resp., P less than 0.05). As an alternative to direct electrical coupling, the possibility of interaction between fibroblasts and nodal cells by capacitive coupling has been considered. Model calculations based on the reconstruction of some fibroblast extensions parallel to nodal cells show that the current which can be transmitted from discharging nodal cells to fibroblasts is negligible. It is concluded that fibroblasts do not participate in the impulse conduction within the sinoatrial node. The origin of the directional differences in conduction velocity in the sinoatrial node must be found in the spatial arrangement of the myocytes and the distribution of the gap junctions between these cells only.
J Mol Cell Cardiol 1992 Jun
PMID:Spatial and functional relationship between myocytes and fibroblasts in the rabbit sinoatrial node. 151 74

In isolated preparations of the simian (Macaca fascicularis) heart, we studied the activation pattern within the sinoatrial node, using the conventional microelectrode technique. After electrophysiological experiments we subjected three preparations to a correlative light microscopical and two to an electron microscopical investigation. The sinoatrial node of the Macaca fascicularis is characterized by unifocal impulse generation. The impulse is propagated preferentially in an oblique direction towards the inferior vena cava, which is a unique direction compared to all other mammals studied so far. Possible consequences for A-V nodal input are discussed. Conduction block was seen in an oblique superior direction towards the atrial septum. In this small zone of blocked conduction double component action potentials could be recorded. The morphology of the sinoatrial node of the Macaca fascicularis is essentially the same as found in other mammals.
J Mol Cell Cardiol 1990 Dec
PMID:Structure and function of the simian sinoatrial node (Macaca fascicularis). 208 59

The prognostic value of EGF-R, IGF-1-R and SS-R, and of cytosolic estrogen-regulated pS2 protein, was studied in patients (pts) with primary breast and advanced ovarian cancer. Ovarian cancer tissues were negative for pS2 (by immunoradiometric assay) IGF-1-R and EGF-R contents (by ligand binding assay, LBA) were of no or moderate prognostic value for breast cancer pts (n = 214). For advanced ovarian cancer pts, EGF-R content determined by LBA (n = 55) showed no prognostic value, whereas EGF-R status (n = 35) determined by immunohistochemistry (MoAb 2E9) significantly correlated with progression of disease (P less than 0.05). In breast cancer pts, both SS-R and pS2 showed no association with tumor size, nodal status and grade. For pS2 the best cut-off level with respect to relapse-free (RFS) and overall survival (OS) was found to be 11 ng/mg protein. Both SS-R (1 g% SS-R+, n = 135; P less than 0.04) and pS2 (27% pS2+, n = 197; P less than 0.001), which were mainly positive in ER+ tumors, were of prognostic value, especially within the subgroups with ER+/PgR+ tumors. Also within N+ and No pts the 5-yr RFS and OS showed a difference between pS2+ and pS2- (33 and 54% for N+, and 31 and 13% difference for No pts). In summary, SS-R and pS2 are valuable prognosticators in breast cancer pts, and prognostic significance of EGF-R in ovarian cancer pts needs further study.
J Steroid Biochem Mol Biol 1990 Dec 20
PMID:Prognostic value of pS2 protein and receptors for epidermal growth factor (EGF-R), insulin-like growth factor-1 (IGF-1-R) and somatostatin (SS-R) in patients with breast and ovarian cancer. 217 64

Electrotonic current spread in the SA node of the rabbit was measured by means of hyperpolarizing current pulses (1 to 10 microA, 60 ms), which were injected intracellularly through a K(+)-perfused suction electrode. The pulses were applied at the beginning, middle or end of the diastolic depolarization phase. The resulting membrane potential change of nodal fibers was measured with microelectrodes. Space constants were calculated by fitting single exponential curves to the data. The input resistance (Rin) of fibers at different sites in the SA node was measured by means of a double barrel microelectrode (current pulses 5.5 to 11 nA, 60 ms) to detect a change in the internal resistance during the diastolic depolarization phase. During diastole the average electrotonic potential increased by 30% (P less than 0.001), the increase of the space constant ranged from 9 to 183% (P less than 0.05). Rin however, did not change during diastole. It is concluded that the electrotonic spread increased phase dependently, due to an increase of membrane resistance; the internal resistance was not phase dependent.
J Mol Cell Cardiol 1990 Apr
PMID:Phase dependency of electrotonic spread of hyperpolarizing current pulses in the rabbit sinoatrial node. 238 76

The contribution to spontaneous activity of three currents INa, If, and Isi was investigated in isolated spontaneously active SA nodal cells. It was demonstrated that isolated cells have electrophysiological properties similar to those of cells in the intact node. Evidence for the contributory role of INa to the upstroke of the action potential was obtained from membrane responsiveness curves and from the observation that Vmax was strongly reduced after the addition of 9 microM TTX to the bathing solution. The relative role of If and Isi as depolarizing diastolic membrane currents was investigated by relating the maximal density of each of these currents to the corresponding DDR during spontaneous activity. Both currents If and Isi-peak appear to be linearly related to DDR, indicating their contributory role to diastolic depolarization. Although the cells studied were heterogeneous with regard to the density of If and Isi we found no evidence for their separation into distinct groups of pacemaker cell types.
J Mol Cell Cardiol 1989 Nov
PMID:Mechanisms of impulse generation in isolated cells from the rabbit sinoatrial node. 248 47

Highly purified thyroglobulin mRNA was isolated from human nodal euthyroid goiter. Full length cDNA was synthesized from 33S RNA by using reverse transcriptase in the presence of human placenta ribonuclease inhibitor. DNA complementary to human Tg mRNA was used in liquid hybridization experiments to determine the quantity of Tg mRNA. The amount of Tg mRNA in euthyroid nodal and congenital goiter was reduced. Tg specific mRNA was absent in thyroid cancer cells.
Mol Biol (Mosk)
PMID:[Thyroglobulin gene expression in human thyroid cells in various types of thyroid pathology]. 258 2

In the bovine nodal conduction tissue we have described the existence of a novel cardiac myosin isoform, immunologically related to the myosin types expressed during skeletal muscle development. Using different monoclonal antibodies specific for the embryonic and the neonatal skeletal myosin heavy chain types we investigated the myosin composition of the rat sino-atrial and atrio-ventricular nodes. We find that nodal conduction tissue fibers of the rat heart contain a distinct cardiac myosin isoform antigenically similar to the skeletal embryonic myosin heavy chain. The expression of this myosin isoform in nodal tissue appears to be developmentally regulated and partially controlled by thyroid hormone. Reactive cardiac fibers were detected in the nodal regions only during fetal development and a few days after birth, whereas very rare labelled fibers could be observed in the adult nodes. This myosin type does not represent a primordial cardiac myosin isoform since it was not detected in the embryonic heart before 13.5 days of gestation. When congenital hypothyroidism was induced in rats, the post-natal disappearance of reactive fibers in the nodal regions was delayed. On the other hand, hypothyroidism induced in the adult rats did not change the number of the reactive nodal fibers with respect to the euthyroid hearts.
J Mol Cell Cardiol 1988 Oct
PMID:An embryonic-like myosin heavy chain is transiently expressed in nodal conduction tissue of the rat heart. 321 2

The feline sinoatrial node has a unifocal impulse generation as previously described for rodents. Its main component is collagen. The primary pacemaker consists of at most 2000 cells, but appears to function normally with less than 500 cells. Primary pacemaker cells are found in the area where empty cells are predominant. A negative correlation between myofilament density and diastolic depolarization rate, known to exist in the rabbit and guinea-pig, is absent in the cat. Gap junctions are seen in the center and in the periphery of the nodal region, but they are extremely rare. The electrophysiological characteristics of the primary pacemaker of the cat are quite similar to those of the rabbit, although the nodal morphology is very different. Abrupt transitions from one cell type into another are observed in the feline sinoatrial node. From this morphological point of view the feline sinoatrial node resembles the canine and human sinoatrial nodes more than the lapine sinoatrial node.
J Mol Cell Cardiol 1986 Oct
PMID:Functional and morphological organization of the cat sinoatrial node. 378 21


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