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At least 775 records · Page 43Linked to original sources
PubMed1987

Dual intrinsic and extrinsic origins of CGRP- and NPY-immunoreactive nerves of rat gut and pancreas.

The origins of nerves containing calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), and substance P were investigated in the rat stomach, pancreas, and colon, using immunocytochemistry combined with retrograde tracing and surgical and chemical denervation procedures. Compared with nerves containing vasoactive intestinal polypeptide (VIP) and galanin, which have primarily local origins in mammalian gut, CGRP-, NPY-, and substance P-immunoreactive nerves revealed dual extrinsic and intrinsic origins. Immunocytochemistry combined with retrograde tracing showed that the extrinsic CGRP- and substance P-immunoreactive nerves in the stomach and pancreas originate from bilateral dorsal root ganglia mainly at levels T8-T11, while those of the colon are derived from bilateral ganglia at S1 and, to a lesser extent, L1 and L6. Chemical denervations showed that neurons in these ganglia form a sensory input to the gut, and that those containing CGRP form the largest proportion. The results of combined retrograde tracing and immunocytochemistry indicated that extrinsic NPY-immunoreactive nerves originate from postganglionic sympathetic neurons lying in the coeliac and inferior mesenteric ganglia. These nerves were located mainly around blood vessels in gut and pancreas, showed sensitivity to 6-hydroxydopamine, and thus are likely to be noradrenergic. The present study provides a detailed mapping of the origins of some of the major peptide-containing nerves of the rat gastroenteropancreatic tract, thus providing further information on the anatomy of the enteric innervation.

Animals↗
PubMed1989

Anterior spinal arteries. Origin and distribution in man.

This study was designed to extend our present knowledge of the origin and distribution of anterior spinal arteries and was carried our using 31 human cadavers with arterial injections of natural latex. The conclusions reached are that there are always one or two anterior spinal arteries (right or left), which proceed from the intracranial segment of the vertebral arteries. These arteries have a descending course, with distribution into the ventral face of the medulla oblongata and the first cervical segments of the medulla spinalis. In cases where there are two anterior spinal arteries, they anastomose with each other to form the common, unpaired and median anterior spinal artery. The different observed locations of the origins of anterior spinal arteries may be systematised into three types. Each of these types has differential characteristics: bilateral origin (type I; 77.4%), unilateral origin (type II; 9.7%) and origin in an intervertebral transversal anastomosis (type III; 12.9%). We do however subdivide the bilateral origin group, according to the calibre of the arteries, into the subtypes 'balanced' (type Ia; 22.6%), 'right dominated' (type Ib; 32.2%) and 'left dominated' (type Ic; 22.6%). The collaterals of the anterior spinal arteries which distribute into the ventral face of the medulla oblongata are described.

Adolescent↗
PubMed1989

The probability of detecting the origin of nondisjunction of autosomal trisomies.

For studying the biology of autosomal trisomies it is necessary to establish the parental origin and meiotic stage of nondisjunction by using genetic markers. Theoretical formulas are obtained for calculating the probability of establishing (1) parental origin and meiotic stage of nondisjunction by using a centromeric marker, (2) parental origin of nondisjunction by using a noncentromeric marker, and (3) meiotic stage, given parental origin of nondisjunction. These theoretical calculations demonstrate that parental origin of nondisjunction can be identified with virtual certainty by utilizing multiple genetic markers along a chromosome arm. Centromeric markers are by themselves inefficient for determining meiotic stage of the error, but the efficiency can be considerably increased if parental origin is known with certainty. Even then, multiple centromeric markers may be necessary.

Alleles↗
PubMed1988

Studies on the role of the phi X174 gene A protein in phi X viral strand synthesis. I. Replication of DNA containing an alteration in position 1 of the 30-nucleotide icosahedral bacteriophage origin.

The influence of a C----G transversion at position 1 of the 30-base pair replication origin of bacteriophage phi X174 replicative form I DNA (phi X RFI) was examined in the RF----single-stranded circular DNA replication pathway catalyzed by the combined action of the purified phi X A protein, the Escherichia coli DNA polymerase III holoenzyme, rep helicase, and single-stranded DNA binding protein (Eisenberg, S., Scott, J.F., and Kornberg, A. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 1594-1597; Reinberg, D., Zipursky, S.L., and Hurwitz, J. (1981) J. Biol. Chem. 256, 13143-13151). RFI DNA containing this transversion was cleaved to RFII by the phi X A protein as effectively as DNA containing the wild-type origin. The altered duplex DNA, however, supported replication at a slower rate (3- to 4-fold) than the wild-type DNA due to a defect in the termination and reinitiation reactions catalyzed by the phi X A protein. This defect resulted in the accumulation of DNA products containing long single strands covalently joined to the mutant DNA. These single strands were susceptible to nuclease S1 and exonuclease VII attack. The defect in the template DNA containing C----G transversion was not corrected when this mutant origin was placed on the same strand with a wild-type origin. This double-origin DNA was also replicated poorly and led to the accumulation of large products, in contrast to the products formed with RFI DNA containing two wild-type 30-base pair replication origins on the same strand.

Bacteriophage phi X 174↗
PubMed1985

Initiation of DNA replication at the primary origin of bacteriophage T7 by purified proteins. Site and direction of initial DNA synthesis.

In vivo, T7 DNA replication is initiated 15% of the distance from the genetic left end of the chromosome. This site, the primary origin of replication, consists of a 200-base pair (bp) intergenic segment from 14.5 to 15.0% within which are located two tandem T7 RNA polymerase promoters (phi 1.1A and phi 1.1B) followed by a 61-bp AT-rich (79% A + T) region. A fragment of T7 DNA containing the primary origin has been inserted into plasmids in order to facilitate studies on initiation in vitro. Initiation of DNA synthesis can be reconstituted using T7 RNA polymerase, T7 DNA polymerase, and T7 origin-containing plasmid DNAs. DNA synthesis is stimulated greatly by the T7 gene 4 protein, an enzyme that has helicase and primase activities. When T7 gene 4 protein is present, replication primarily yields partially replicated Y-form molecules as observed by electron microscopy. Synthesis is unidirectional and the branches of the Y-form molecules are uniform in size, with the branch point of the Y located at the origin. Using restriction enzyme analysis, DNA synthesis has been shown to proceed in the same direction (rightward with respect to the T7 genetic map) as transcription from the two promoters located at the origin. Initiation of DNA synthesis in the opposite direction requires the addition of a single-stranded DNA-binding protein (Fuller, C.W., and Richardson, C.C. (1985) J. Biol. Chem. 260, 3197-3206). The initial products of DNA synthesis have been analyzed by polyacrylamide gel electrophoresis. These DNAs have 10 to 60 ribonucleotides covalently linked to their 5' termini. These RNA primers arise by transcription from each of the two promoters, phi 1.1A and phi 1.1B, located within the primary origin.

Base Sequence↗
PubMed1986

The origins and insertions of the extraocular muscles: development, histologic features, and clinical significance.

The tendinous origins and insertions of the extraocular muscles were studied embryologically by macroscopic and microscopic methods. It is concluded from this investigation that these tendons of origin and insertion arise from mesenchymal tissue similar to that of their respective muscles. These tendon-muscle groups have developed from superior and inferior mesenchymal complexes. The origins of the extraocular muscles are attached to the periorbita by an interlocking of the tendinous and muscular fibers, which allows for mobility of the extraocular muscles in all extreme directions of gaze and also results in a strong mechanical mooring for these muscles. Avulsion at the origins of the extraocular muscles following severe traction or trauma is rare. The additional origin of the superior and medial rectus muscles to the dura of the optic nerve explains the pain that may occur on movement of the eye in optic neuritis. Optic nerve compression and thyroid myopathy is explained by mucopolysaccharide and inflammatory cell infiltration of the muscular interdigitations that extend up to the site of origin of the rectus muscles. Findings of this investigation suggest that the association of ptosis and superior rectus muscle underaction may be due to a persistence of fibrous tissue that has endured from embryologic development between the superior rectus and levator palpebrae superioris muscles. Superior oblique tendon sheath syndrome is explained by embryologic strands remaining between the tendon of the superior oblique muscle and the trochlea. The insertions of the rectus muscles extend from the equator of the eye to the limbus early on in development. By processes of differential degeneration between the sclera and the rectus tendon, posterior recession of the tendon from the limbus, and contemporaneous growth of the anterior segment of the eye, these tendons reach their adult location only between the ages of 18 months and 2 years. In strabismus surgery, measurements for muscle adjustments should be assessed from the limbus rather than from the sites of insertion of these tendons. In the series of patients with esotropia, no mechanical abnormalities were noted in relationship to the insertions of the medial or lateral recti muscles. Furthermore, no correlation was found between the site of insertion of the medial rectus muscle and the degree of esotropia.

Child, Preschool↗
PubMed1979

Role of the somitic mesoderm in the development of the thorax in bird embryos. II. Origin of thoracic and appendicular musculature.

The regional embryonic origin of trunk and limb musculature was determined through heterospecific homotopic or heterotopic transplantations of quail somitic or somiticsomatopleural mesoderm into chick hosts, and through localized X-irradiation of the somitic mesoderm. Experiments were performed on 2-day embryos. Results show that the myoblastic component of all truncal and appendicular muscles is of somitic origin. Intra- and perimuscular connective tissue as well as tendons are of somatopleural origin. X-ray destruction of the somitic mesoderm at and beyond the wing level resulted in the complete or almost complete absence of musculature in the wing and corresponding truncal region. The mapping of the cephalocaudal origin of the various muscles was found to be as follows: Intrinsic and extrinsic muscles of the wing and scapular girdle Somites 12-20 Grand pectoral muscle Somites 12-22 Intercostal muscles Somites 19-26 Abdominal muscles Somites 27-29 Intrinsic and extrinsic muscles of the leg and pelvic girdle Somites 26-32 Dorsal and intervertebral muscles Metameric level, specific origin In the heterotopic transplantations, the grafted somitic mesoderm gave rise to site-specific morphogenesis, irrespective of the cephalocaudal level of its origin. This result demonstrates that, at 2 days of incubation, the myogenic somitic cells are not regionalized.

Animals↗
PubMed1979

[Origin of cutaneous smooth muscles in birds (author's transl)].

The origin of smooth muscles in the skin of bird embryos has been analyzed in heterospecific quail/chick recombinants. The somitic mesoderm of the wing level of 2-day chick embryos was replaced by homotopic or heterotopic somitic mesoderm from quail embryos. The cellular constitution of tissues was observed in twelve recombinant embryos at 17 or 18 days of incubation. Results show that feather smooth muscles and vascular smooth muscles have the same origin as the cutaneous mesenchyme in which they differentiate. They are of somatopleural origin in the wing integument and of somitic (dermatomal) origin in the dorsal integument. This study further reveals that the muscular and connective tissue wall of blood vessels does not have the same embryonic origin as the endothelium. It is suggested that the latter originates from the primitive aorta.

Animals↗
PubMed1993

[The significance of electrocardiography in locating original sites of ventricular tachycardia].

The sites of origin of ventricular tachycardia (VT) in 12 patients were located by ECG during the episode and further confirmed by catheter mapping. The results showed that there were 14 sites of origin of VT in the 12 patients from ECG in which 1 site was incompletely mapped by catheter and 12 of the other 13 original sites were confirmed by the catheter endocardial or epicardial mapping. Of the 12 original sites of VT, the locating of 11 ones were completely consistent with those from ECG, which was 84.6% of the 13 original sites. Moreover, 8 of the 12 patients had been successfully treated by catheter direct or radiofrequency current ablation and 1 of the 12 by successful surgical operation. Thus, the original sites of VT located by ECG was reliable and could shorten the time of catheter mapping during non-pharmacological therapy of VT.

Adolescent↗
PubMed1995

Anatomy of the origin of the deep femoral artery.

OBJECTIVE: To study the variability in the level of origin of the deep femoral artery in relation to the different patterns of origin of the femoral circumflex arteries. DESIGN: 124 femoral triangles obtained from cadavers were dissected. The origins of the circumflex femoral arteries were classified into two groups. In group A medial and lateral circumflex arteries arose from the deep femoral artery. In group B either one or both femoral circumflex arteries arose from the common femoral artery. The distance of origin of the deep femoral artery from the mid point of the inguinal ligament was measured in both groups and compared. SETTING: Department of Anatomy, Faculty of Medicine, Colombo. RESULTS: A statistically significant difference was noted in the two groups regarding the level of origin of the deep femoral artery. CONCLUSION: There is a distal migration of the level of origin of the deep femoral artery when either one or both circumflex femoral arteries arose from the common femoral artery.

Anthropometry↗
PubMed1996

Arterial hypertension in the adult population of Guadeloupe, and associated factors in subjects of African origin.

This study was designed to estimate the prevalence of hypertension in Guadeloupe, the French West Indies, and to evaluate the risk factors associated with hypertension in the largest ethnic group, that of African origin. Households were randomly selected using a two-stage systematic sample of districts and then of houses; all adults aged 18 years in the household were included. In total, 1043 men and women were studied. Blood pressure, plasma glucose concentrations and gamma-glutamyl transferase activity were measured, hypertensive treatment and lifestyle factors recorded. The prevalence of hypertension, age-standardized to the Guadeloupe population was 21% and 26% in men and women of African origin, 28% and 22% in those of Indian-origin and 18% and 16% for other origins. The vast majority of subjects were unaware of their hypertension (90% of men, 74% of women). After adjustment for age, factors associated with high blood pressure in the 826 adults of African origin were: obesity, hyperglycemia, low educational level and family history of hypertension and of stroke. Additional factors in women were alcohol consumption, gamma-glutamyl transferase activity, physical inactivity, occupational category and a retired status, even after adjustment for age. Measures must be taken to diagnose hypertension early, particularly in individuals of African and Indian origin. An effective education program is needed, with an emphasis on life-style factors associated with obesity: diet and physical activity.

Adolescent↗
PubMed1996

Magnetic resonance angiography of the origins of the supraaortic arteries: comparison of single and double volume acquisition 3D time of flight.

PURPOSE: The authors have optimized the technique of Magnetic Resonance Angiography (MR-angio) in the study of the origins of the supraaortic arteries. METHODS: Twenty healthy volunteers, mean age 21.5, were studied with MR-angio of the origins of the supraaortic arteries; a 1 T superconductive magnet (Impact) with body coil was used. All the volunteers were studied using Time of flight (TOF), and two acquisition techniques: single volume FISP (fast imaging with steady-state precession) 3D TONE (titled optimized non-saturating excitation) and double volume FISP 3D TONE with 30% overlapping. The images were acquired on the axial plane following the positioning of three pre-saturation pulses. RESULTS: Regarding the visualization of the different components of the origins of the supraaortic arteries, a statistical analysis was worked out using the Mann Whitney test (p < 0.05); there was no statistically significant difference between two techniques. Regarding the visualization of the various segments (origin, 1/3 proximal, 1/3 middle, 1/3 distal), although the double volume did on the one hand allow a better visualization of the more distal vascular components (statiscally significant difference), on the other it induced the presence of artefacts with decreased the quality of the image as a whole. DISCUSSION: In our experience TOF 3D technique with TONE and single volume has well identified the origin of the vertebral arteries, while, in several cases, TOF 3D technique with TONE and double volume did not permit the visualization of the origin of the vertebral arteries due to the presence of the artefacts from overlapping. CONCLUSION: From our experience we have established that the TOF 3D technique with TONE and single volume makes it possible to obtain MR-angio of a high diagnostic quality in a short time (10-15 mn).

Adult↗
PubMed2006

Regulating the licensing of DNA replication origins in metazoa.

Eukaryotic DNA replication is a highly conserved process; the proteins and sequence of events that replicate animal genomes are remarkably similar to those that replicate yeast genomes. Moreover, the assembly of prereplication complexes at DNA replication origins ('DNA licensing') is regulated in all eukaryotes so that no origin fires more than once in a single cell cycle. And yet there are significant differences between species both in the selection of replication origins and in the way in which these origins are licensed to operate. Moreover, these differences impart advantages to multicellular animals and plants that facilitate their development, such as better control over endoreduplication, flexibility in origin selection, and discrimination between quiescent and proliferative states.

Animals↗
PubMed2002

Stable association of mitotic cyclin B/Cdc2 to replication origins prevents endoreduplication.

We show that in fission yeast the mitotic B type cyclin Cdc13/Cdc2 kinase associates with replication origins in vivo. This association is dependent on the origin recognition complex (ORC), is established as chromosomes are replicated, and is maintained during G2 and early mitosis. Cells expressing an orp2 (ORC2) allele that reduces binding of Cdc13 to replication origins are acutely prone to chromosomal reduplication. In synchronized endoreduplicating cells, following Cdc13 ablation, replication origins are coordinately licensed prior to each successive round of S phase with the same periodicity as in a normal cell cycle. Thus, ORC bound mitotic Cyclin B/Cdc2 kinase imposes the dependency of S phase on an intervening mitosis but not the temporal licensing of replication origins between each S phase.

CDC2 Protein Kinase↗
PubMed2001

Interaction of fission yeast ORC with essential adenine/thymine stretches in replication origins.

BACKGROUND: Eukaryotic DNA replication is initiated from distinct regions on the chromosome. However, the mechanism for recognition of replication origins is not known for most eukaryotes. In fission yeast, replication origins are isolated as autonomously replicating sequences (ARSs). Multiple adenine/thymine clusters are essential for replication, but no short consensus sequences are found. In this paper, we examined the interaction of adenine/thymine clusters with the replication initiation factor ORC. RESULTS: The SpOrc1 or SpOrc2 immunoprecipitates (IPs) containing at least four subunits of SpORC, interacted with the ars2004 fragment, which is derived from a predominant replication origin on the chromosome. SpORC-IPs preferentially interacted with two regions of the ars2004, which consist of consecutive adenines and AAAAT repeats and are essential for ARS activity. The nucleotide sequences required for the interaction with SpORC-IPs correspond closely to those necessary for in vivo ARS activity. CONCLUSION: Our results suggest that the SpORC interacts with adenine/thymine stretches, which have been shown to be the most important component in the fission yeast replication origin. The presence of multiple SpORC-binding sites, with certain sequence variations, is characteristic for the fission yeast replication origins.

Adenine↗
PubMed1999

The fission yeast homologue of Orc4p binds to replication origin DNA via multiple AT-hooks.

The origin recognition complex (ORC) was originally identified in the yeast Saccharomyces cerevisiae as a protein that specifically binds to origins of DNA replication. Although ORC appears to play an essential role in the initiation of DNA replication in the cells of all eukaryotes, its interactions with DNA have not been defined in species other than budding yeast. We have characterized a Schizosaccharomyces pombe homologue of the ORC subunit, Orc4p. The homologue (Orp4p) consists of two distinct functional domains. The C-terminal domain shows strong sequence similarity to human, frog, and yeast Orc4 proteins, including conserved ATP-binding motifs. The N-terminal domain contains nine copies of the AT-hook motif found in a number of DNA-binding proteins, including the members of the HMG-I(Y) family of chromatin proteins. AT-hook motifs are known from biochemical and structural studies to mediate binding to the minor groove of AT-tracts in DNA. Orp4p is essential for viability of Sc. pombe and is expressed throughout the cell cycle. The Orp4 protein (and its isolated N-terminal domain) binds to the Sc. pombe replication origin, ars1. The DNA binding properties of Orp4p provide a plausible explanation for the characteristic features of Sc. pombe origins of replication, which differ significantly from those of Sa. cerevisiae.

Amino Acid Sequence↗
PubMed2003

Kinetics of ATP binding to the origin recognition complex of Saccharomyces cerevisiae.

Origin recognition complex (ORC), a candidate initiator of chromosomal DNA replication in eukaryotes, binds specifically to ATP through two of its subunits (Orc1p and Orc5p). In this study, we investigated the kinetics of ATP binding to ORC by a filter binding assay. The Kd values for the ATP of wild-type ORC and ORC-1A (mutant ORC containing Orc1p with a defective Walker A motif) were less than 10 nm, suggesting that the affinity of Orc5p for ATP is very high. On the other hand, the Kd values for the ATP of ORC-5A (mutant ORC containing Orc5p with a defective Walker A motif) was much higher (about 1.5 microm), suggesting that the affinity of Orc1p for ATP is relatively low in the absence of origin DNA. ATP dissociated more rapidly from its complex with ORC-5A than from its complex with ORC-1A, suggesting that the ATP-Orc5p complex is more stable than ATP-Orc1p complex. Origin DNA fragments decreased the Kd value of ORC-5A for ATP and stabilized the complex of ATP with ORC-5A. Wild-type ORC, ORC-1A, and ORC-5A required different concentrations of ATP for specific binding to origin DNA. All of these results imply that ATP binding to Orc5p, ATP binding to Orc1p, and origin DNA binding to ORC are co-operatively regulated, which may be important for the initiation of DNA replication.

Adenosine Triphosphate↗
PubMed2002

Site-specific ORC binding, pre-replication complex assembly and DNA synthesis at Schizosaccharomyces pombe replication origins.

Previous studies have shown that the Schizo saccharomyces pombe Orc4 subunit is solely responsible for in vitro binding of origin recognition complex (ORC) to specific AT-rich sites within S.pombe replication origins. Using ARS3001, a S.pombe replication origin consisting of four genetically required sites, we show that, in situ as well as in vitro, Orc4 binds strongly to the Delta3 site, weakly to the Delta6 site and not at all to the remaining sequences. In situ, the footprint over Delta3 is extended during G(1) phase, but only when Cdc18 is present and Mcm proteins are bound to chromatin. Moreover, this footprint extends into the adjacent Delta2 site, where leading strand DNA synthesis begins. Therefore, we conclude that ARS3001 consists of a single primary ORC binding site that assembles a pre-replication complex and initiates DNA synthesis, plus an additional novel origin element (Delta9) that neither binds ORC nor functions as a centromere, but does bind an as yet unidentified protein throughout the cell cycle. Schizosaccharomyces pombe may be an appropriate paradigm for the complex origins found in the metazoa.

Base Composition↗