SEARCH · PubMed Health

Results for “Meanders”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 451 records · Page 25Linked to original sources

PubMed1989

The structure of yeast enolase at 2.25-A resolution. An 8-fold beta + alpha-barrel with a novel beta beta alpha alpha (beta alpha)6 topology.

The three-dimensional structure of yeast enolase has been determined by the multiple isomorphous replacement method followed by the solvent flattening technique. A polypeptide model, corresponding with the known amino acid sequence, has been fitted to the electron density map. Crystallographic restrained least-squares refinement of the model without solvent gave R = 20.0% for 6-2.25-A resolution with good geometry. A model with 182 water molecules and 1 sulfate which is still being refined has presently R = 17.0%. The molecule is a dimer with subunits related by 2-fold crystallographic symmetry. The subunit has dimensions 60 X 55 X 45 A and is built from two domains. The smaller N-terminal domain has an alpha + beta structure based on a three-stranded antiparallel meander and four helices. The main domain is an 8-fold beta + alpha-barrel. The enolase barrel is, however, different from the triose phosphate isomerase barrel; its topology is beta beta alpha alpha (beta alpha)6 rather than (beta alpha)8 as found in triose phosphate isomerase. The inner beta-barrel is not entirely parallel, the second strand is antiparallel to the other strands, and the direction of the first helix is also reversed with respect to the other helices. This supports the hypothesis that some enzymes evolved independently producing the stable structure of beta alpha barrels with either enolase or triose phosphate isomerase topology. The active site of enolase is located at the carboxylic end of the barrel. A fragment of the N-terminal domain and two long loops protruding from the barrel domain form a wide crevice leading to the active site region. Asp246, Glu295, and Asp320 are the ligands of the conformational cation. Other residues in the active site region are Glu168, Asp321, Lys345, and Lys396.

Binding Sites↗

PubMed1990

Color Doppler flow imaging of liver tumors.

A differential diagnosis of liver tumors was attempted on the basis of the pattern of blood flow within and around tumors on color Doppler flow images. The study comprised 35 patients with liver mass lesions: 20 patients had hepatocellular carcinoma, six had hemangiomas, four had metastatic liver cancers, one had cholangiocellular carcinoma, one had focal fatty liver, and three had liver cysts. A basket pattern (a fine blood-flow network surrounding the tumor nodule) was observed in 15 (75%) of the 20 hepatocellular carcinomas. An image of vessels within the tumor (blood flow that runs into and branches within the tumor) was observed in 13 (65%) of the 20 hepatocellular carcinomas. These two findings were observed only in hepatocellular carcinomas; even when the tumor was smaller than 2 cm in diameter, these findings were observed frequently. In the patients with multiple hepatic metastases, a "detour" pattern (a dilated portal vein meandering around the tumor nodules) was observed. In three of the six hemangiomas, a "spot" pattern (color-stained dots or patches in the central region of the tumor) was seen. Our experience suggests that hepatocellular carcinomas have a characteristic appearance on color Doppler flow images.

Adenoma, Bile Duct↗

PubMed2004

Developmental dimorphism: consequences for larval behavior and dispersal potential in a marine gastropod.

Specific effects of alternative developmental programs on swimming and settlement behavior for marine larvae have not been identified experimentally. A major impediment to this research has been the rarity of species with variable development. Here, we compared traits related to movement and habitat selection for different ontogenetic stages of long-lived, feeding larvae (planktotrophic) and short-lived, nonfeeding larvae (lecithotrophic) of the herbivorous gastropod Alderia modesta. Newly hatched planktotrophic larvae swam in meandering paths with equal rates of upward and downward movement. As planktotrophic larvae developed towards competence (physiological ability to metamorphose), their swimming paths became straighter, faster, and increasingly directed towards the bottom, traits shared by newly hatched lecithotrophic larvae. Despite differing in developmental history, competent planktotrophic (32-d-old) and lecithotrophic larvae (competent upon hatching) exhibited qualitatively similar swimming behaviors and substrate specificity. However, lecithotrophic larvae moved downward at twice the speed of competent planktotrophic larvae, potentially producing a 5-fold higher rate of contact with the bottom in natural flows. Competent larvae swam downwards rather than passively sinking, even though sinking rates were faster than swimming speeds; active swimming may allow larvae to keep the velum extended, permitting rapid response to chemical settlement cues and promoting successful habitat colonization. Differences between larvae of the two development modes may reflect fine-tuning by selection of traits important for dispersal and settlement into patchy adult habitats.

Age Factors↗

PubMed1985

Perivascular demyelinization of cochlear neurons in two neonates.

Localized perivascular demyelinization of the peripheral processes of cochlear neurons was observed in surface preparations of the osseous spiral lamina in two neonates, one a premature infant with erythroblastosis fetalis, the other a full-term infant with cyanotic congenital heart disease. In both cases the cause of the demyelinization was unknown. Both infants had severe edema as a result of congestive heart failure and anoxia. The serum bilirubin level in the erythroblastotic child appeared too low to have caused injury to the nerve fibers. The demyelinization was most striking in the lower half of the basal turn. It was observed only in the immediate vicinity of meandering stretches of capillaries as they crossed the nerve fibers. In the premature infant there was hair cell loss throughout the cochlea; in the other there was no hair cell loss, but a malformed labyrinth of the Mondini type.

Cochlear Nerve↗

PubMed1992

Identification of the plant nucleolonema using silver staining of serial ultrathin sections.

A simple silver staining technique was applied to serial ultrathin sections of Vicia faba root tip meristems to investigate the structural organization of the nucleoli. The procedure consists of three steps: hydrophilic Lowicryl resin embedding, preparation of ribbons of serial ultrathin sections, and silver impregnation. This technique provided good contrast for a filamentous structure, previously called the "nucleolonema", in nucleoli at the light microscope level. Silver appears to react with some acidic proteins involved with ribosomal RNA transcription, since the major constituents of the nucleolonema are believed to be active rRNA transcriptional units. Tracing the nucleolonema through serial ultrathin sections strongly suggests that the nucleolonema is meandering and partly coiling within the nucleolus. The present technique permits identification of the nucleolonema in other plant species and investigation of its three-dimensional structural organization.

Cell Nucleolus↗

PubMed2002

Large cerebral arteriovenous malformation presenting with venous ischemia in the contralateral hemisphere. Case report.

The authors report a rare case in which a large cerebral arteriovenous malformation (AVM) located in the left parietooccipital region presented with venous ischemia in the contralateral hemisphere. A 74-year-old man was admitted to the hospital because he was experiencing a loss of appetite, disorientation, and left hemiparesis. Computerized tomography scans revealed a low-density area in the right temporal lobe. Angiography demonstrated a large AVM in the left parietooccipital lobe and dilation, stagnation, and meanders of cortical veins in the contralateral hemisphere. The authors speculated that the elevated sinus pressure caused by a huge venous return of blood from the AVM produced venous ischemia in the contralateral hemisphere.

Aged↗

PubMed2002

Traumatic neuroma of the anterior cervical nerve root with no subjective episode of trauma. Report of four cases.

The authors report four cases of traumatic neuroma in the cervical nerve root in patients with no history of trauma. In one case the patient presented with intractable pain in the left upper extremity and motor paresis of the left shoulder, and in another case the patient suffered neuropathic pain in the left forearm. In both cases, magnetic resonance (MR) imaging revealed an intradural extramedullary mass lesion in the ipsilateral cervical nerve root; these MR imaging signals were similar to the intensity of the spinal cord. Intraoperatively, fusiform enlargement of the anterior cervical nerve root was detected in the subarachnoid space. Histological examination showed a meandering change of axons accompanied by mild axonal swelling and a thin myelin sheath, which are consistent with the typical pathological features of traumatic neuroma. Postoperatively, pain resolved in both cases. The authors also investigated two traumatic neuromas of the anterior cervical nerve root in autopsy cases in which there was no history of trauma and no significant neurological signs suggestive of traumatic neuroma. The authors conclude that traumatic neuroma of the anterior cervical nerve root may develop following an unnoticed minor brachial plexus injury at birth or a forgotten traction injury of the upper extremity in childhood, and the lesion may be accompanied by various case-specific clinical features.

Adult↗

PubMed1998

[Study of the fifth-type cell in the olfactory epithelium].

The olfactory epithelium has been shown to contain fifth-type cells and microvillar cells and olfactory receptor cells along with supporting and basal cells. However, the morphological differences among them are unknown, especially between the former two, and most of their functions are still unclear. In this study, the fifth-type cell and the microvillar cell in the olfactory epithelium of mouse were micromorphologically investigated by SEM and TEM. With the aim of elucidation their functions, the morphological change in these cells after resection of olfactory bulb were studied. In addition, the changes in the olfactory epihelium after HRP injections into the postganglionic fiber for the trigeminal nerve and the olfactory bulb were examined. The TEM observation revealed that the fifth-type cell has finger-like microvilli, which are strong and straight. The microvilli were characterized by a specific core structure consisting of microfilament bundles. On the other band, the microvilli of the microvillar cell were meandering and had no core structure, indicating that the two cells are clearly different types. By SEM observation, neither the fifth-type cell nor the microvillar cell was found in the normal olfactory epithelium. When the olfactory cillial mat disappeared as a result of recection of the olfactory bulb, the fifth-type cell became observable. On the 300th-day after the resection, it was found that the olfactory receptor cells had disappeared and the microvilli of the supporting cells were shortened. Thus, the surface structure of the microvillar cell became clearly observable. Then, the microvilli were found to be shorter than those of the fifth-type cell and were distributed radially. Neither the fifth-type cell nor the microvillar cell was not affected by resection of the olfactory bulb. Most of the olfactory vesicles were HRP positive after the HRP injection into the olfactory bulb; however, HRP was not detected in either the fifth-type cells or the microvillar cells. After the HRP injection into the trigeminal postganglionic fiber, it was detectable in part of the nerves in the lamina propria mucosa and the epithelal basement, but not in the fifth-type cell or microvillar cell. These results suggest that the fifth-type cell is a mechanoreceptor for a system other than the olfactory one and the microvillar cell is a kind of supporting cell in an early stage or final stage near death.

Animals↗

PubMed2002

The critical role of basement membrane-independent laminin gamma 1 chain during axon regeneration in the CNS.

We have addressed the question of whether a family of axon growth-promoting molecules known as the laminins may play a role during axon regeneration in the CNS. A narrow sickle-shaped region containing a basal lamina-independent form of laminin exists in and around the cell bodies and proximal portion of the apical dendrites of CA3 pyramidal neurons of the postnatal hippocampus. To understand the possible function of laminin in axon regeneration within this pathway, we have manipulated laminin synthesis at the mRNA level in a slice culture model of the lesioned mossy system. In this model early postnatal mossy fibers severed near the hilus can regenerate across the lesion and elongate rapidly within strata lucidum and pyramidale. In slice cultures of the postnatal day 4 hippocampus, 2 d before lesion and then continuing for 1-5 d after lesion, translation of the gamma1 chain product of laminin was reduced by using antisense oligodeoxyribonucleotides and DNA enzymes. In the setting of the lesioned organotypic hippocampal slice, astroglial repair of the lesion and overall glial patterning were unperturbed by the antisense or DNA enzyme treatments. However, unlike controls, in the treated, lesioned slices the vast majority of regenerating mossy fibers could not cross the lesion site; those that did were very much shorter than usual, and they took a meandering course. In a recovery experiment in which the DNA enzyme or antisense oligos were washed away, laminin immunoreactivity returned and mossy fiber regeneration resumed. These results demonstrate the critical role of laminin(s) in an axon regeneration model of the CNS.

Aging↗

PubMed1976

[Comparative morphological studies on the vascular systems of testes in cattle, swine, horse and dog under functional conditions].

The metacrylate and latex corrosion techniques were used to establish that the vascular system of testes is based on one coherent principle in common domestic mammals. The cone-shaped Plexus pampiniformis consists of numerous venous rami, between 0.25 mm and 1.0 mm in thickness and forming a dense vascular network, which practically encase the spiral-shaped A. spermatica interna (cooling coil principle). The testicular veins and arteries in the Tunica albuginea constitute a somewhat voluminous layer of vessels for dissipation of heat, with rami branching off radially into the testicular parenchyma. Most of the artieral rami with radial penetration of the testicular parenchyma turn towards the surface in the mediastinum testis for three-shape ramification. The vascular rami are characterised by countless meanders, primarily for temperature control, pulse flattening for more regular and even blood flow, and blood reflex pumping.

Animals↗

PubMed1976

[Vital microscopic investigation of terminal blood vessels in patients with diabetes mellitus].

It is reported on findings of vital-microscopic investigations at the terminal vascular system of the conjunctiva bulbi and the mucous membrane of the lips carried out on 50 juvenile diabetics and 50 test persons of the same age. By quantitative establishment of the morphological and functional changes of the vessels and the aggregation of the erythrocytes in the different regions of the terminal vascular system we succeeded in delimitating all 50 diabetes as individuum or as collective (x equals 10.7 +/- 1.5) from the test persons (x equals 3.4 +/- 0.9) by means of a point system (p less than 0.001). In 4 figures typical vascular findings are demonstrated. No pathognomonic significance was ascribed to the individual vascular findings. The morphological and functional changes of the vascular wall are regarded as an expression of fundamental reactive possibilities of the vessels of the terminal vascular system after influence of different factors of risk. As criteria of the findings were used: venular sacculations, meander-like forms, convolutions, haemorrhages, aneurysms, reticular structures, varieties of calibres, changed arteriolarvenular relations of the inner diameter of the vessels, constant proof of aggregates of erythrocytes with temporary standstill of the flow in the different parts of the terminal vascular system. The author is of the opinion that with simultanuous establishment of the morphological and functional changes of wall of the vessel and content of the vessel degenerative changes in diabetes mellitus are provable earlier than at the eye-ground by means of ophthalmocoscopy when only morphological findings are established. The reciprocities between the vascular changes and the rheological properties of the blood are described.

Adult↗

PubMed1976

[A case of frontal arteriovenous malformation with optochiasmatic arachnoiditis as an initial symptoms (author's transl)].

A surgically cured case of chronic optochiasmal arachnoiditis presumably caused by concomitant right frontal arteriovenous malformation (AVM) is reported. When a 12-year-old boy, suffering from blurred vision for about 1 month, visited the Ophthalmological Clinic of Hirosaki University Hospital, only a chiasmal lesion was suspected because neuro-ophthalmological examination revealed no more than ophthalmic signs, such as bilateral diminution of vision (Vd, Vs = 0.2), concentric narrowing of visual fields and slight bilateral papilledema. The patient was referred to the Neurosurgical clinic for further examination. Left carotid angiograms showed no abnormalities but, thereafter the brain scintigram revealed an abnormal hot area in the right frontoparietal region. A right carotid angiography demonstreated an AVM in the posterior part of the right frontal lobe. This was fed through the right anterior and middle cerebral arteries and drained into the superior sagittal sinus through meandering dilated cortical vein.

Arachnoiditis↗

PubMed1999

[Two cases of frosted retinal angiitis with central retinal vein occlusion].

BACKGROUND: Frosted retinal angiitis usually occurs in children, and has a good prognosis. We report two cases of unilateral frosted retinal angiitis in adults. They resulted in visual degradation because of associated central retinal vein occlusion and neovascular glaucoma. CASES: Case 1 was a 36-year-old female. Almost all retinal veins and some retinal arteries had vasculitis in her right eye, and the veins were slightly dilated and sheathed. Case 2 was a 23-year-old female. Angle hypopyon was observed in her left eye. Retinal veins were dilated, meandered, and sheathed. Retinal hemorrhages were also observed. In both cases, systemic steroid therapy gradually improved the retinal vasculitis, but central retinal vein occlusions gradually developed, and in spite of systemic administration of urokinase and panretinal photocoagulation, neovascular glaucoma developed, and visual acuity became degraded in both cases. CONCLUSION: Two cases of frosted retinal angiitis complicated by retinal vein occlusion were reported. Careful observation of retinal blood flow is necessary in frosted retinal angiitis in adults.

Adult↗

PubMed2000

The bacterial replicative helicase DnaB evolved from a RecA duplication.

The RecA/Rad51/DCM1 family of ATP-dependent recombinases plays a crucial role in genetic recombination and double-stranded DNA break repair in Archaea, Bacteria, and Eukaryota. DnaB is the replication fork helicase in all Bacteria. We show here that DnaB shares significant sequence similarity with RecA and Rad51/DMC1 and two other related families of ATPases, Sms and KaiC. The conserved region spans the entire ATP- and DNA-binding domain that consists of about 250 amino acid residues and includes 7 distinct motifs. Comparison with the three-dimensional structure of Escherichia coli RecA and phage T7 DnaB (gp4) reveals that the area of sequence conservation includes the central parallel beta-sheet and most of the connecting helices and loops as well as a smaller domain that consists of a amino-terminal helix and a carboxy-terminal beta-meander. Additionally, we show that animals, plants, and the malarial Plasmodium but not Saccharomyces cerevisiae encode a previously undetected DnaB homolog that might function in the mitochondria. The DnaB homolog from Arabidopsis also contains a DnaG-primase domain and the DnaB homolog from the nematode seems to contain an inactivated version of the primase. This domain organization is reminiscent of bacteriophage primases-helicases and suggests that DnaB might have been horizontally introduced into the nuclear eukaryotic genome via a phage vector. We hypothesize that DnaB originated from a duplication of a RecA-like ancestor after the divergence of the bacteria from Archaea and eukaryotes, which indicates that the replication fork helicases in Bacteria and Archaea/Eukaryota have evolved independently.

Amino Acid Sequence↗

PubMed2000

Microanatomy and ultrastructure of the protonephridial system in the larva of the limpet, Patella vulgata L. (Mollusca, Patellogastropoda).

The microanatomy and ultrastructure of the larval excretory system of Patella vulgata L., 1758 has been examined by means of semithin and ultrathin serial sections, reconstructions, and transmission electron microscopy. The protonephridial system appears after torsion and consists of two terminal flame bulbs with narrow, ciliated ducts. Whereas the polyciliary terminal cells (cyrtocytes) are only slightly asymmetrically placed below the mantle cavity, the distal excretory ducts and their openings show remarkable asymmetry due to torsion. Further larval ultrafiltration sites with identical fine-structure (meandering slits with diaphragms covered by extracellular matrix) are present in the solitary rhogocytes (pore cells). The presence of larval protonephridia is regarded as plesiomorphic for Mollusca and the Trochozoa (Spiralia) as a whole and the specific conditions (asymmetry, simplicity) in Patella are probably plesiomorphic for the Gastropoda.

Animals↗

PubMed2000

Microanatomy and ultrastructure of the excretory system of two pelagic opisthobranch species (Gastropoda: Gymnosomata and Thecosomata).

The microanatomy and ultrastructure of the excretory system of Pneumoderma sp. (Gymnosomata) and Creseis virgula Rang, 1828 (Thecosomata) have been investigated by means of semithin serial sections, reconstructions and transmission electron microscopy. The studies revealed a functional metanephridial system consisting of a heart with a single ventricle and auricle in a pericardial cavity and a single kidney in both species. Podocytes in the atrial wall of the pericardial epithelium are the site of ultrafiltration, whereas the flat epithelium of the kidney with numerous basal infoldings and a dense microvillous border on the luminal surface suggests modification of the ultrafiltrate. In Pneumoderma sp., additional loci of ultrafiltration with identical fine structure (meandering slits with diaphragms covered by extracellular matrix) occur in the solitary rhogocytes (pore cells). The presence of podocytes situated on the atrial wall in representatives of two higher opisthobranch taxa contradicts former ideas on the loss of the primary site of ultrafiltration in the ancestors of the Opisthobranchia.

Animals↗

PubMed2001

Prepulse inhibition deficits and perseverative motor patterns in dopamine transporter knock-out mice: differential effects of D1 and D2 receptor antagonists.

Dopamine is known to regulate several behavioral phenomena, including sensorimotor gating and aspects of motor activity. The roles of dopamine D1 and D2 receptors in these behaviors have been documented in the rat literature, but few reports exist on their role in mice. We used dopamine transporter (DAT) (-/-) mice to examine the behavioral consequences of a chronically hyperdopaminergic state, challenging them with the preferential dopamine D2 receptor antagonist raclopride and D1 receptor antagonist SCH23390. At baseline, DAT (-/-) mice exhibited deficient sensorimotor gating as measured by prepulse inhibition (PPI) of the startle response, exhibited nonfocal preservative patterns of locomotion, and were hyperactive in a novel environment. Pretreatment with raclopride significantly increased PPI in the DAT (-/-) mice, whereas SCH23390 had no significant effect. Blockade of D2 receptors did not affect the predominantly straight patterns of motor behavior produced by the DAT (-/-) mice, but antagonism of D1 receptors significantly attenuated the preservative patterns, producing more of a meandering behavior seen in the DAT (+/+) control mice. Both D1 and D2 receptor antagonists decreased the hyperactivity seen in the DAT (-/-) mice. These findings support the role of the D2, but not the D1, receptor in the modulation of PPI in mice. Furthermore, D1 receptor activation appears to be the critical substrate for the expression of preservative patterns of motor behavior, whereas both D1 and D2 receptors appear to regulate the amount of motor activity.

Animals↗

PubMed2001

Vascular changes in psoriatic knee joint synovitis.

OBJECTIVE: To evaluate the diagnostic utility of standard arthroscopy supported by a computerized image analysis system; and to examine and quantify the macroscopic appearance of blood vessels in selected anatomical areas, comparing 2 groups of patients with PsA and RA with refractory knee joint synovitis (KJS) for vascular marking (VM) features and VM scores, as well as for the relationship between respective VM scores and local and systemic KJS disease activity indices. METHODS: Standard arthroscopy was carried out on 39 knees (20 PsA, 19 RA). Videorecordings of the examination were reanalyzed using a computer image analysis system and software. The appearance of vascular markings was assessed and separately scored for the areas of surface synovium (capsular, CVM), villous proliferation (villous, VVM), and synovium adherent to cartilage (pannus, PVM). Indices of systemic (erythrocyte sedimentation rate, ESR) and local KJS disease activity (clinical index) were obtained before arthroscopy. The morphology and scores of the distinct VM were compared between PsA and RA groups, as was the relationship between respective VM scores and ESR and KJS clinical indices. RESULTS: Distinctive VM features were observed for PsA and RA KJS in each separate synovial architecture examined. VVM and CVM scores were significantly correlated with each other in PsA knees, and were significantly higher in PsA compared with RA. In both diseases, VVM and CVM scores were not related to KJS duration or activity or to ESR values, but in RA they were directly correlated with KJS activity. Moreover, the VVM capillary feature "meandering with tight convolutions," considered unique to psoriatic skin, was observed in the synovium of 13 PsA (65%) and one RA KJS (5.5%). The mean KJS duration of the PsA group with typical VVM was significantly lower than the group without VVM (2.6 +/- 1.77 vs 9.4 +/- 8.28 yrs). CONCLUSION: Our macroscopic observations of distinct changes in VM expression in selected anatomical areas of PsA and RA KJS suggest possible pathogenetic differences between the 2 diseases. The typical morphology and higher intensity of villous vascularization, in both early and chronic disease, and the different clinical relevance of VVM scores in PsA compared with RA KJS support the potential use of vascular markings as reliable outcome measures of the PsA process in KJS.

Arthritis, Psoriatic↗