Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Origination patterns”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed1988

Relationship between endocardial activation of SA valve and right atrium in domestic fowl.

We mapped endocardial activation in the isolated, perfused chicken heart to determine how excitation spreads from the sinoatrial (SA) valve, the avian pacemaker structure, to the atrioventricular (AV) ring. We found activity originating from one of three sites on the right valvule with the upper half of this valvule being the dominant origin. Only one heart exhibited an origin lower on the right valvule. We never observed activity originating from the left valvule. Depending on the valvular origin, two patterns of atrial activation were observed. The dominant pattern emerged from an upper to middle origin on the right valvule and involved two preferential conduction pathways. One pathway followed the right transverse arch and pectinate muscle medially to depolarize the AV ring from a posterior medial direction. Activation along the second pathway traveled caudally along the right valvule and then followed the sinus septum to approach the AV ring from an anterior lateral direction. An atypical pattern resulted from one heart exhibiting a lower origin on the right valvule. In this case, preferential atrial conduction only followed the lower pathway. This could represent an entrance block located cranially in the right valvule preventing normal activation of the right transverse arch and pectinate muscle.

Animals↗
PubMed1981

Aortic origin of conus coronary artery. Evidence of postnatal coronary development.

The conus coronary artery has been reported to arise independently from the aorta in approximately 45 per cent of hearts. In this study, 305 necropsy specimens were examined to determine the origin of the conus coronary artery and variations in patterns of origin with respect to age. Three patterns were recognised: 1, in which the conus artery arose from the aorta independently of the right coronary artery; 2, in which the conus artery and the right coronary arose from a common ostium; and 3, in which only the right coronary artery took origin from the right aortic sinus. The relative incidence of the three patterns varied with age. Pattern 1 was recognised in 14 to 24 per cent of specimens from patients under the age of 2 years, whereas in older patients, it occurred in 41 to 63 per cent. These data suggest that aortic origin of the conus arterial ostium may appear in some individuals between 2 and 4 years of age, and they support the concept that some coronary arterial patterns are not fully established at the time of birth.

Adolescent↗
PubMed1990

Neutralisation patterns among recent British and North American feline calicivirus isolates from different clinical origins.

The neutralisation patterns of 103 recent isolates of feline calicivirus from cats with chronic stomatitis or acute feline calicivirus disease, and from cats with neither oral nor respiratory disease were compared. There were no statistically significant differences between the proportions of isolates from each clinical source neutralised by individual feline calicivirus cat antisera. Different antisera showed widely differing degrees of cross reactivity; antisera to the most widely used vaccine strain F9 being the most cross reactive, neutralising 54 per cent of all the field isolates, and antisera to a field isolate LS015 the next most cross reactive, neutralising 29 per cent of the field isolates. However, the cross reactivity of antisera to early British isolates (A4, 68/40 and 69/1112) was much reduced (overall less than 10 per cent) whereas in the early 1970s 65 per cent of 117 field isolates from clinically normal cats were neutralised by A4 antiserum, and 40 per cent by each of 68/40 and 69/1112 antisera. This suggests a change in the spectrum of antigenicity among feline calicivirus isolates over the past 15 years. However, the cross reactivity of F9 antisera appeared to be similar to that in earlier studies. The relevance of these findings to vaccination is discussed.

Animals↗
PubMed1991

Vascularity of tumors in children: evaluation with color Doppler imaging.

Twenty-one tumors in 20 children were evaluated with duplex and color Doppler imaging to determine the value of the technique in assessing the origin and pattern of vascular supply and the degree of neovascularity. The origin of the vascular supply was detected correctly in 12 of 13 tumors that were subsequently resected. In five children, this aided in determining the organ from which the tumor originated, and in one child, it established the presence of a tumor by showing blood flow in the center of a suspected abscess. In 18 tumors, color Doppler imaging showed the pattern of the vascular supply. Eleven had a peripheral pattern, and seven had a central, branching pattern. Although individual tumor types appeared to have characteristic patterns of vascular supply, these were not specific enough to aid in making a specific diagnosis. When the degree of intratumor neovascularity was graded on the basis of the findings on color Doppler imaging, it agreed with the results of histologic evaluation in 16 of 19 tumors. In one tumor, neovascularity was overestimated, and in two, it was markedly underestimated. Our experience suggests that color Doppler imaging is useful in detecting the origin and pattern of vascular supply and the degree of intratumoral blood flow in a variety of solid tumors in children.

Adolescent↗
PubMed1996

Lipid apheresis in an animal model causes in vivo changes in lipoprotein electrophoretic patterns.

Lipid apheresis, a new extracorporeal procedure based on plasma delipidation and showing promise as a possible treatment for atherosclerosis, was recently reported for the first time from this laboratory [Cham et al., J Clin Apheresis 10:61-69, 1995]. In the present study lipid apheresis was applied to hypercholesterolemic and normocholesterolemic roosters to examine its effect on plasma lipoprotein particles. This procedure resulted in conspicuous changes in electrophoretic patterns of plasma lipoproteins. The electrophoretic mobilities of all the lipoprotein fractions had changed considerably. Lipid stainable material was present in at least three bands in the alpha-globulin area. In particular, changes in the electrophoretic region of high-density lipoproteins were observed. Lipid apheresis markedly induced the anti-atherogenic pre- beta-high-density lipoproteins. The observed changes induced by lipid apheresis were more pronounced in the hyperlipidemic animals compared with the normocholesterolemic controls. A novel pre-alpha-lipoprotein band was observed soon after lipid apheresis. This lipoprotein band had a density larger than 1.21. At approximately 150 minutes after lipid apheresis, the electrophoretic pattern had almost returned to its original base pattern. Lipid apheresis results in plasma lipoprotein changes which may induce reverse cholesterol transport and shows promise as a possible treatment of atherosclerosis.

Animals↗
PubMed2001

Noradrenergic regulation of hippocampal place cells.

The influence of noradrenergic input to the hippocampus was assessed by recording hippocampal place cells and by modulating the noradrenergic tone with a selective agonist and antagonist of the alpha2-autoreceptors. The rats received intraperitoneal injection of 5 microg/kg of dexmedetomidine (DEX), an alpha2-agonist, 0.2 mg/kg of atipamezole (ATI), an alpha2-antagonist, or saline. Hippocampal place cells were recorded in a familiar rectangular environment and in three types of new environments (rectangle, square, and cylinder). Recordings in the familiar environment were conducted in two phases, either before (early phase) or after (late phase) the exposure to new environments. In the familiar environment, DEX significantly increased the mean firing rate of hippocampal interneurons, while ATI increased the mean firing rate of pyramidal cells. Only ATI in the early phase of the experiment impaired spatial selectivity. Both drugs induced field rotations in the early phase of the study, but in the late phase DEX decreased, while ATI increased field stability in the familiar environment. The drug effects in the new environment were dependent on degree of novelty. No difference between treatments was observed in the new rectangle, but in the square and cylinder, ATI increased the mean firing rate, number of fields, and field area compared to other treatments. Stability of the original firing fields in the familiar rectangle was dependent on type of interfering environment and drug treatment. Exposure to another rectangle had the smallest impact, and exposure to a square the largest impact, on the original field pattern. ATI impaired stability of the original field after exposure to a rectangular and cylinder, while the impairing effect of DEX was only observed after exposure to a cylinder. In conclusion, increased noradrenergic tone increases the firing rate of hippocampal place cells, especially when the experimental situation and environment are new, but this increase is spatially nonselective. Furthermore, manipulation of the noradrenergic tone in either direction leads to instability of firing fields.

Adrenergic alpha-Agonists↗
PubMed2004

The evolution of arthropod limbs.

Limb morphology across the arthropods is reviewed using external morphological and internal anatomical data from both recent and fossil arthropods. Evolutionary trends in limb structure are identified primarily by reference to the more rigorous of the many existing phylogenetic schemes, but no major new phylogenetic inferences are presented. Tagmosis patterns are not considered, although the origins and patterns of heteronomy within the postantennulary limb series are analysed. The phenomenon of annulation is examined and two basic types of annuli are recognised: terminal and intercalary. The annulation of the apical segment of a limb results in the formation of terminal flagella, and is typical of primarily sensory appendages such as insect and malacostracan antennules and maxillary palps of some hexapods. Intercalary annulation, arising by subdivision of existing subterminal segments, is common, particularly in the tarsal region of arthropodan walking limbs. Differentiating between segments and annuli is discussed and is recognised as a limiting factor in the interpretation of fossils, which usually lack information on intrinsic musculature, and in the construction of groundplans. Rare examples of secondary segmentation, where the criteria for distinguishing between segments and annuli fail, are also highlighted. The basic crown-group arthropodan limb is identified as tripartite, comprising protopodite, telopodite and exopodite, and the basic segmentation patterns of each of these parts are hypothesised. Possible criteria are discussed that can be used for establishing the boundary between protopodite and telopodite in limbs that are uniramous through loss of the exopodite. The subdivision of the protopodite, which is typical of the postantennulary limbs of mandibulates, is examined. The difficulties resulting from the partial or complete failure of expression of articulations within the mandibulate protopodite and subsequent incorporation of partial protopodal segments into the body wall, are also discussed. The development and homology between the various exites, including gills, on the postantennulary limbs of arthropods are considered in some detail, and the question of the possible homology between crustacean gills and insect wings is critically addressed. The hypothesis that there are only two basic limb types in arthropods, antennules and postantennulary limbs, is proposed and its apparent contradiction by the transformation of antennules into walking limbs by homeotic mutation is discussed with respect to the appropriate level of serial homology between these limbs.

Adaptation, Physiological↗
PubMed1993

Molecular evidence that the spiny mouse (Acomys) is more closely related to gerbils (Gerbillinae) than to true mice (Murinae).

Spiny mice of the genus Acomys traditionally have been classified as members of the Murinae, a subfamily of rodents that also includes rats and mice with which spiny mice share a complex set of morphological characters, including a unique molar pattern. The origin and evolution of this molar pattern, documented by many fossils from Southern Asia, support the hypothesis of the monophyly of Acomys and all other Murinae. This view has been challenged by immunological studies that have suggested that Acomys is as distantly related to mice (Mus) as are other subfamilies (e.g., hamsters: Cricetinae) of the muroid rodents. We present molecular evidence derived from DNA.DNA hybridization data that indicate that the spiny mouse Acomys and two African genera of Murinae, Uranomys and Lophuromys, constitute a monophyletic clade, a view that was recently suggested on the basis of dental characters. However, our DNA.DNA hybridization data also indicate that the spiny mice (Acomys) are more closely related to gerbils (Gerbillinae) than to the true mice and rats (Murinae) with which they have been classified. Because Acomys and the brush-furred mice Uranomys and Lophuromys share no derived morphological characters with the Gerbillinae, their murine morphology must have evolved by convergence, including the molar pattern previously considered to support the monophyly of the Murinae.

Animals↗
PubMed2004

A model-based optimization framework for the inference on gene regulatory networks from DNA array data.

MOTIVATION: Identification of the regulatory structures in genetic networks and the formulation of mechanistic models in the form of wiring diagrams is one of the significant objectives of expression profiling using DNA microarray technologies and it requires the development and application of identification frameworks. RESULTS: We have developed a novel optimization framework for identifying regulation in a genetic network using the S-system modeling formalism. We show that balance equations on both mRNA and protein species led to a formulation suitable for analyzing DNA-microarray data whereby protein concentrations have been eliminated and only mRNA relative concentrations are retained. Using this formulation, we examined if it is possible to infer a set of possible genetic regulatory networks consistent with observed mRNA expression patterns. Two origins of changes in mRNA expression patterns were considered. One derives from changes in the biophysical properties of the system that alter the molecular-interaction kinetics and/or message stability. The second is due to gene knock-outs. We reduced the identification problem to an optimization problem (of the so-called mixed-integer non-linear programming class) and we developed an algorithmic procedure for solving this optimization problem. Using simulated data generated by our mathematical model, we show that our method can actually find the regulatory network from which the data were generated. We also show that the number of possible alternate genetic regulatory networks depends on the size of the dataset (i.e. number of experiments), but this dependence is different for each of the two types of problems considered, and that a unique solution requires fewer datasets than previously estimated in the literature. This is the first method that also allows the identification of every possible regulatory network that could explain the data, when the number of experiments does not allow identification of unique regulatory structure.

Algorithms↗
PubMed1989

Gantzer's muscle-like variation inserted into the forearm flexor retinaculum.

A rare muscle variation belonging to the forearm flexor muscle group has been observed in three forearms out of nearly 200 Japanese cadavers. It arose from the well developed fascia of the superficial forearm flexor group, crossed the median nerve obliquely and posteriorly lying radial to that nerve, and was inserted into the flexor retinaculum. The muscle variations in the three cases were discussed according to the concept of "corrected" nerve-muscle specificity and conservative morphology. They were conclusively ascribable to the original antebrachial flexor group of Yamada. This seemed to indicate that the variations were related or identical to Gantzer's muscle, and that they showed a possible original or archaic pattern of the original antebrachial flexors.

Forearm↗
PubMed1984

Microsurgical anatomy of the proximal segments of the middle cerebral artery.

The microvascular anatomy of the proximal segments (M1 and M2) of the middle cerebral artery (MCA) was studied in 70 unfixed brain hemispheres from 35 cadavers. The arteries were injected with a tinted polyester resin and dissected under magnification by microsurgical techniques. The authors studied the outer diameter (OD), length, site of origin, and pattern of branching of the main trunk, secondary trunks, and the initial insular portion of the cortical branches of the MCA. The degree of mobilization of the arteries lying over the insular cortex was also assessed. The main trunk of the MCA, which had an OD of 3 +/- 0.1 mm bilaterally and a length of 15 +/- 1.1 mm in the right hemisphere and 15.7 +/- 1.3 mm in the left hemisphere, could be divided into four groups: Group I: absence of a main division (that is, a single-trunk type of MCA) (in 6% of cases); Group II: bifurcation (64%); Group III: trifurcation (29%); and Group IV: quadrifurcation (1%). The secondary trunks resulting from the division of the main trunk of the MCA had a mean OD ranging from 1.4 to 2.3 mm and a mean length that varied from 12.1 to 14.9 mm. The mean OD of the cortical branches measured near their origin in the main and secondary trunks indicated that the angular artery was the largest vessel, with a mean OD of 1.5 mm on both sides of the brain. The temporopolar artery was the smallest, with a mean OD of 0.8 mm in the right hemisphere and 0.9 mm in the left hemisphere. The authors also describe the patterns of origin of the cortical vessels from the main trunk (early branches) and from the secondary trunks, as well as their branching pattern at the site of origin (single vessels and common stems). These anatomical data indicate that it is possible to perform microvascular reconstructive procedures, such as anastomosis, grafting, and reimplantation of branches in the insular area. The advantages of using unfixed specimens, intravascular injections, and magnification to reproduce in vivo conditions as closely as possible are also discussed.

Cerebral Arteries↗
PubMed1979

Guidance of regrowing sensory axons after cutaneous nerve lesions in the cat.

1. Individual type I sensory neurons in cutaneous nerves typically innervate two to four type I cutaneous mechanoreceptors (Haarscheiben). The extent to which these neurons replicate the original innervation patterns of the type I receptors after peripheral nerve regeneration and the means by which these neurons are guided back to their old receptor sites during regeneration were studied in cats using neurophysiological techniques. 2. By recording activity of type I neurons in small cutaneous nerves and isolated dorsal rootlets, it was possible to map the distribution of these neurons in the skin. Maps made before nerve lesion were compared to maps made after recovery from nerve crush and transection. 3. Fibers regenerating after nerve crush return to their old receptor sites, probably by following their old Schwann tubes in the distal stump of the nerve, and replicate the original receptor innervation pattern. Essentially all the type I fibers successfully regenerate in this case. 4. In contrast, after nerve transection the regenerating fibers do not restore the original innervation pattern, although they do preferentially return to other old type I receptor sites. About 60% of the type I fibers reinnervate the skin after transection. 5. These observations provide a basis for the difference in functional recovery seen after crush and transection lesions of peripheral nerves.

Animals↗
PubMedDate not supplied

Multiple squamous cell carcinomas of the head and neck show different phenotypes of allelic loss patterns suggesting different clonal origin of carcinogenesis.

BACKGROUND: Multiple squamous cell carcinomas in the head and neck are not such a rare phenomenon in patients. To examine if these tumors have the same genetic basis or not, we investigated genetic alterations such as allelic loss in such multiple tumors to see if they showed identical patterns. MATERIALS AND METHODS: Patterns of the loss of heterozygosity at 3p, 9p and 17p loci were analyzed in multiple head and neck squamous cell carcinomas of the same patient. RESULTS: Metachronous laryngeal and tongue tumors of a patient were found to have identical patterns of allelic loss, while synchronous tumors of three other patients had different patterns of such loss. CONCLUSION: Our data support the idea that field carcinogenesis caused by exposure of oral, laryngeal and pharyngeal mucosa to carcinogens may lead to the independent development of synchronous non-related tumors at different sites of the upper aerodigestive tract.

Adult↗
PubMed1997

Replication profile of Saccharomyces cerevisiae chromosome VI.

BACKGROUND: An understanding of the replication programme at the genome level will require the identification and characterization of origins of replication through large, contiguous regions of DNA. As a step toward this goal, origin efficiencies and replication times were determined for 10 ARSs spanning most of the 270 kilobase (kb) chromosome VI of Saccharomyces cerevisiae. RESULTS: Chromosome VI shows a wide variation in the percentage of cell cycles in which different replication origins are utilized. Most of the origins are activated in only a fraction of cells, suggesting that the pattern of origin usage on chromosome VI varies greatly within the cell population. The replication times of fragments containing chromosome VI origins show a temporal pattern that has been recognized on other chromosomes--the telomeres replicate late in S phase, while the central region of the chromosome replicates early. CONCLUSIONS: As demonstrated here for chromosome VI, analysis of the direction of replication fork movement along a chromosome and determination of replication time by measuring a period of hemimethylation may provide an efficient means of surveying origin activity over large regions of the genome.

Cell Cycle↗
PubMed1997

Diversity of feline Chlamydia psittaci revealed by random amplification of polymorphic DNA.

DNA samples from C. psittaci including 6 strains of feline origin, 10 strains of avian origin, 1 strain of ovine origin and 1 strain of guinea pig origin were amplified each with three 10-nucleotide (nt) primers and four > 18-nt primers. Amplified products were separated by polyacrylamide gel electrophoresis. Eight patterns were recognized by random amplification of polymorphic DNA (RAPD) fingerprinting of C. psittaci: 2 patterns of feline origin, 5 patterns of avian origin and 1 pattern of guinea pig origin. DNA of feline or guinea pig origin was clearly distinguished from the other strains of C. psittaci by RAPD analysis, as shown by the absence of any common fragments in electrophoresis. The RAPD analysis indicated at least 2 types of feline C. psittaci. The RAPD typing is suggested as a convenient tool for molecular epidemiology of chlamydial infection.

Animals↗
PubMed2002

Retroposed new genes out of the X in Drosophila.

New genes that originated by various molecular mechanisms are an essential component in understanding the evolution of genetic systems. We investigated the pattern of origin of the genes created by retroposition in Drosophila. We surveyed the whole Drosophila melanogaster genome for such new retrogenes and experimentally analyzed their functionality and evolutionary process. These retrogenes, functional as revealed by the analysis of expression, substitution, and population genetics, show a surprisingly asymmetric pattern in their origin. There is a significant excess of retrogenes that originate from the X chromosome and retropose to autosomes; new genes retroposed from autosomes are scarce. Further, we found that most of these X-derived autosomal retrogenes had evolved a testis expression pattern. These observations may be explained by natural selection favoring those new retrogenes that moved to autosomes and avoided the spermatogenesis X inactivation, and suggest the important role of genome position for the origin of new genes.

Animals↗
PubMed1994

Chromosomal DNA replication initiates at the same origins in meiosis and mitosis.

Autonomously replicating sequence (ARS) elements are identified by their ability to promote high-frequency transformation and extrachromosomal replication of plasmids in the yeast Saccharomyces cerevisiae. Six of the 14 ARS elements present in a 200-kb region of Saccharomyces cerevisiae chromosome III are mitotic chromosomal replication origins. The unexpected observation that eight ARS elements do not function at detectable levels as chromosomal replication origins during mitotic growth suggested that these ARS elements may function as chromosomal origins during premeiotic S phase. Two-dimensional agarose gel electrophoresis was used to map premeiotic replication origins in a 100-kb segment of chromosome III between HML and CEN3. The pattern of origin usage in premeiotic S phase was identical to that in mitotic S phase, with the possible exception of ARS308, which is an inefficient mitotic origin associated with CEN3. CEN3 was found to replicate during premeiotic S phase, demonstrating that the failure of sister chromatids to disjoin during the meiosis I division is not due to unreplicated centromeres. No origins were found in the DNA fragments without ARS function. Thus, in both mitosis and meiosis, chromosomal replication origins are coincident with ARS elements but not all ARS elements have chromosomal origin function. The efficiency of origin use and the patterns of replication termination are similar in meiosis and in mitosis. DNA replication termination occurs over a broad distance between active origins.

Chromosomes, Fungal↗