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PubMed2002

Meandering right pulmonary vein to the left atrium and inferior vena cava: the first case with associated anomalies.

We report a case of a healthy, asymptomatic 6-year-old boy in whom an anomalous right pulmonary vein was noted to drain into both the inferior vena cava and left atrium in association with findings consistent with scimitar syndrome. The anomalous pulmonary vein took a very circuitous route through the lungs before draining into the left atrium, a condition previously termed "meandering pulmonary vein." To aid in the diagnosis, cardiovascular magnetic resonance imaging and magnetic resonance angiography were used to delineate this complex course and the connection of the anomalous pulmonary vein. To our knowledge, this is the 1st reported case of a meandering pulmonary vein with dual drainage to the inferior vena cava and left atrium in association with other anomalies.

Child↗

PubMed1995

"Meandering" pulmonary veins: report of a case in an asymptomatic 12-year-old girl.

We report a case of a healthy, asymptomatic 12-year-old girl in whom anomalous pulmonary venous connection to the left atrium occurred as an isolated congenital anomaly. This condition, termed "meandering" pulmonary veins, is closely related to scimitar syndrome and is usually associated with hypogenesis of the right lung and dextropositioning of the heart. To our knowledge, ours is only the second reported case of meandering pulmonary veins occurring as an isolated anomaly.

Child↗

PubMed1996

Further evidence for a unique developmental compartment in the cerebellum of the meander tail mutant mouse as revealed by the quantitative analysis of Purkinje cells.

The cerebellum of the meander tail mutant mouse (mea/mea) is characterized by a relatively normal cytoarchitecture posteriorly with an abrupt transition to an anterior region in which there is abnormal foliation, agranularity, and Purkinje cell (PC) ectopia. This study presents the results of a qualitative and quantitative analysis of the PC in the mea/mea cerebellum. Developmental and morphological analyses reveal that the PC in the anterior region of the mea/mea cerebellum do not form a monolayer during the first week of postnatal development as they do in the wild type mouse. In the adult mea/mea, the dendrites of these ectopic cells are atrophic and disoriented. Quantitative studies in adult animals reveal that while the total number of PC is normal, the number of PC in the affected anterior region of the mea/mea cerebellum is greater than the number of PC in the anterior lobe, as classically defined by the primary fissure, of the normal animal. These data suggest that 1) the developmental morphology of the PC in the anterior region is abnormal, probably due to the lack of granule cells at early postnatal times; 2) the total number of PC in the cerebellum is normal, and 3) the defect is not restricted to the anterior lobe but involves a portion of the posterior lobe. The latter supports the notion that the mutant gene affects a unique developmental compartment in the cerebellum which does not coincide with the classic adult boundary, the primary fissure, between the anterior and posterior lobes.

Animals↗

PubMed2001

Mutation of proline 409 to arginine in the meander region of cytochrome p450c17 causes severe 17 alpha-hydroxylase deficiency.

We elucidated the molecular basis of 17 alpha-hydroxylase deficiency in a Chinese patient with male pseudohermaphroditism. The patient is a compound heterozygote, carrying two different mutant alleles in the CYP17 gene. The first mutation, g.6333--6341delGACTCTTTCA, located in exon 8, was reported in a Thai patient living in a rural village in Thailand. We suggest that g.6333--6341delGACTCTTTCA may be a prevalent mutation causing P450c17 deficiency in Southeast Asia. The second mutation is a missense mutation, g.5582C>G, located in exon 7, changing the codon 409 from CCG to CGG, and changing the coded amino acid from proline to arginine, i.e., P409R. This proline residue is conserved in P450c17 of other species and other human P450 proteins. Site-directed mutagenesis, in vitro expression, and functional analysis of the P409R mutant in COS-1 cells show that it has a complete lack of 17 alpha-hydroxylase activity. The proline residue probably causes a turn in the meander region of P450c17, and we hypothesize, by comparison to homologous proteins, that the change in the protein conformation may abolish heme incorporation or may prevent P450c17 from interacting with electron donors.

Adolescent↗

PubMed1996

Developmental analysis of GFAP immunoreactivity in the cerebellum of the meander tail mutant mouse.

It is thought that Bergmann glial fibers assist in the inward migration of granule cells. Model systems in which there is a perturbation of either the migrating cells or the glial cell population have been useful in understanding the migratory process. In the meander tail mutant mouse, the anterior cerebellar region is agranular, whereas the posterior cerebellum is relatively unaffected by the mutation. This study presents a qualitative analysis of the development of cerebellar radial glia in mea/mea and +/mea mice aged from postnatal day 0 to adult, using an antibody against the glia specific antigen, glial fibrillary acidic protein. The results indicate a slight delay in the onset of immunoreactivity in the mea/mea cerebellum and abnormal glial formation in the anterior and posterior regions by postnatal day 5. At postnatal day 11, the full complement of labeled fibers appears to be present and although they appear abnormal in formation, they eventually reach the surface and terminate in oddly shaped and irregularly spaced endfeet. In adult mea/mea and +/mea mice, as compared to the early postnatal stages, there is a significant reduction in GFAP immunoreactive fibers. Cresyl violet stained adult mea/mea sections revealed the presence of ectopic granule cells in radial columns and small clumps at the surface of and within the molecular layer of the caudal cerebellum. Quantitative analyses revealed a 4- to 5-fold increase in the number of ectopic granule cells in lobule VIII of the mea/mea when compared with the +/mea cerebellum. These results suggest that the radial glia in the mea/mea cerebellum exhibit some uncharacteristic morphologies, but that these abnormalities are most likely the consequence of environmental alterations produced by the mutant gene.

Age Factors↗

PubMed2006

Assessing the effects of alternative setback channel constraint scenarios employing a river meander migration model.

River channel migration and cutoff events within large river riparian corridors create heterogeneous and biologically diverse landscapes. However, channel stabilization (riprap and levees) impede the formation and maintenance of riparian areas. These impacts can be mitigated by setting channel constraints away from the channel. Using a meander migration model to measure land affected, we examined the relationship between setback distance and riparian and off-channel aquatic habitat formation on a 28-km reach of the Sacramento River, California, USA. We simulated 100 years of channel migration and cutoff events using 11 setback scenarios: 1 with existing riprap and 10 assuming setback constraints from about 0.5 to 4 bankfull channel widths (bankfull width: 235 m) from the channel. The percentage of land reworked by the river in 100 years relative to current (riprap) conditions ranged from 172% for the 100-m constraint setback scenario to 790% for the 800-m scenario. Three basic patterns occur as the setback distance increases due to different migration and cutoff dynamics: complete restriction of cutoffs, partial restriction of cutoffs, and no restriction of cutoffs. Complete cutoff restriction occurred at distances less than about one bankfull channel width (235 m), and no cutoff restriction occurred at distances greater than about three bankfull widths (approximately 700 m). Managing for point bars alone allows the setbacks to be narrower than managing for cutoffs and aquatic habitat. Results suggest that site-specific "restriction of cutoff" thresholds can be identified to optimize habitat benefits versus cost of acquired land along rivers affected by migration processes.

California↗

PubMed1991

Spinocerebellar projection in the meander tail mutant mouse: organization in the granular posterior lobe and the agranular anterior lobe.

The cerebellum of the mutant mouse, meander tail, is characterized by normal cytoarchitecture posteriorly and abnormal, agranular cortex anteriorly. Anterograde WGA-HRP tracing analysis of the spinocerebellar projection reveals typical mossy fiber labeling posteriorly in lobule VIII. However, in the anterior cortex, a finer, more diffuse pattern of labeling is seen, unlike the distinct banded pattern of mossy fiber rosettes which characterizes the spinocerebellar projection in the normal animal.

Animals↗

PubMed1992

Expression of the Purkinje cell specific zebrin antigens in the cerebellum of the meander tail mutant mouse.

The cerebellum of the meander tail mutant mouse is characterized by normal cytoarchitecture in the posterior lobe and agranular, abnormal cytoarchitecture in the anterior lobe. The Purkinje cells form a monolayer in the posterior lobe but are dispersed throughout the cortex of the anterior lobe. Examination of these cells with the zebrin antibodies demonstrates that in spite of the morphologic and laminar disorganization of these cells in the anterior lobe, they are organized into the appropriate number of correctly positioned immunopositive zebrin clusters.

Animals↗

PubMed2006

The relationship between scimitar syndrome, so-called scimitar variant, meandering right pulmonary vein, horseshoe lung and pulmonary arterial sling.

We report a case in which a meandering right pulmonary vein connecting to the left atrium is associated with hypoplasia of the right lung, horseshoe lung, abnormal pulmonary lobation, and abnormal branching of the pulmonary arteries. We discuss its relationship to the so-called scimitar variant, and to the scimitar syndrome itself.

Bronchoscopy↗

PubMed2006

A familial variant of the Scimitar syndrome with a meandering pulmonary vein.

We report a rare variant of the Scimitar syndrome, in which the right lower pulmonary vein takes a meandering course before finally connecting in normal fashion to the left atrium. The pulmonary parenchymal segment drained by the tortuous vein is supplied by a systemic collateral artery, which was coiled via a catheter. We also closed the intracardiac defects by surgery. The elder brother of the patient had classical Scimitar syndrome.

Abnormalities, Multiple↗

PubMed1998

Identification of a meander region proline residue critical for heme binding to cytochrome P450: implications for the catalytic function of human CYP4B1.

Alignment of xenobiotic-metabolizing P450 protein sequences highlights an invariant proline residue in the meander region two amino acids N-terminal to the distal arginine of the putative ERR triad thought to be important for heme binding. This occurs as a serine in the sequences derived from human CYP4B1 gDNA and both human lung and placental CYP4B1 cDNAs. Reversion of this serine to the conserved proline residue (Ser427 --> Pro) by site-directed mutagenesis conferred the ability to incorporate heme on the human placental enzyme. Mutation of the corresponding proline in rabbit CYP4B1 (Pro422 --> Ser) abolished heme incorporation. Membrane preparations of human CYP4B1(Pro) and rabbit CYP4B1(Pro), but not the corresponding CYP4B1(Ser) variants, supported lauric acid hydroxylation preferentially at the omega-position. Purified, reconstituted human CYP4B1(Pro) and rabbit CYP4B1(Pro) formed 12-hydroxylauric acid at rates of 17-21 min-1, and both enzymes were also C-8 to C-10 fatty acid omega-hydroxylases preferentially, with total rates of hydroxylation decreasing in the order C-12 > C-10 > C-9 > C-8. Finally, neither human nor rabbit CYP4B1(Pro) formed detectable levels of any hydroxylated testosterone metabolites. Therefore, the presence of a consensus Pro-X-Arg motif is critical for incorporation of the heme prosthetic group in human and rabbit CYP4B1 proteins expressed in insect cells. Native human CYP4B1, expressed in vivo, is likely to be functionally impaired if Pro427 is required for holoenzyme expression in mammalian cells.

Animals↗

PubMed2005

Meanders and reconnection-collision sequences in the standard nontwist map.

New global periodic orbit collision and separatrix reconnection scenarios exhibited by the standard nontwist map are described in detail, including exact methods for determining reconnection thresholds, methods that are implemented numerically. Results are compared to a parameter space breakup diagram for shearless invariant curves. The existence of meanders, invariant tori that are not graphs, is demonstrated numerically for both odd and even period reconnection for certain regions in parameter space. Implications for transport are discussed.

Magnetics↗

PubMed2006

Breakup of shearless meanders and "outer" tori in the standard nontwist map.

The breakup of shearless invariant tori with winding number omega=(11+gamma)(12+gamma) (in continued fraction representation) of the standard nontwist map is studied numerically using Greene's residue criterion. Tori of this winding number can assume the shape of meanders [folded-over invariant tori which are not graphs over the x axis in (x,y) phase space], whose breakup is the first point of focus here. Secondly, multiple shearless orbits of this winding number can exist, leading to a new type of breakup scenario. Results are discussed within the framework of the renormalization group for area-preserving maps. Regularity of the critical tori is also investigated.

Journal Article↗

PubMed2006

Scimitar syndrome versus meandering pulmonary vein: evaluation with three-dimensional computed tomography.

We report two cases of abnormal configuration of the pulmonary venous system of the right lung evaluated with the use of three-dimensional spiral computed tomography (3D-CT). In the first case, an unusual form of scimitar syndrome was detected, consisting of two scimitar veins uniting into a common trunk immediately before their confluence into the inferior vena cava (IVC). The second case concerns a meandering pulmonary vein that followed a circuitous course through the right lung and came in close proximity to the IVC, before draining the entire right lung to the left atrium. In both cases, 3D-CT enabled a non-invasive, detailed anatomic evaluation of the right pulmonary vascular bed.

Adolescent↗

PubMedDate not supplied

Meander tail: a recessive mutant located in chromosome 4 of the mouse.

A variable kinked-tail mutant was found in 1974 in a moderately inbred stock of mice at Iowa State University, Ames. It was named meander tail and was shown to be completely recessive. Study 8 alizarin-stained skeletons showed all degrees of ankylosis or fusions of tail vertebrae and occasionally other vertebrae. Extreme examples had great reduction in number of tail vertebrae. Affected mice over 2 weeks old commonly also show some unsteadiness, presumably a pleiotropic effect of the mutant. Less commonly, one or both hind legs showed some paralysis. Linkage tests of the mutant, symbolized mea, place it fairly close to brown, b, in chromosome 4, and apparently in the small segment between Ps and Pt.

Animals↗

PubMedDate not supplied

Meandering ocular toxocariasis.

Ocular toxocariasis affects the eye in three recognizable patterns: a peripheral inflammatory mass in a quiet eye, posterior pole granuloma, or painless endophthalmitis. The present case photographically documents a new form of ocular involvement, that of periodic intraretinal meandering, followed by quiescence with encapsulation, reemergence, and renewed migration. The similar behavior of the Toxocara canis larva in the animal model and the serologic confirmation of Toxocara canis by ELISA testing establishes the diagnosis in the present case. Photocoagulation is the treatment of choice.

Adolescent↗

PubMed2001

Critical wavelength for river meandering.

A fully nonlinear modal analysis identifies a critical centerline wave number q(c) for river meandering that separates long-wavelength bends, which grow to cutoff, from short-wavelength bends, which decay. Exact, numerical, and approximate analytical results for q(c) rely on the Ikeda, Parker, and Sawai [J. Fluid Mech. 112, 363 (1981)] model, supplemented by dynamical equations that govern the river migration and length. Predictions also include upvalley bend migration at long times and a peak in lateral migration rates at intermediate times. Experimental tests are suggested.

Journal Article↗

PubMed2002

[Systematics meanders of microsporidia].

Meanders of systematics of Microsporidia. Taxonomical questions of Microsporidia, its systematic position and evolutionary relationship with other Eukaryota are discussed. Utilizations of modern methods of investigations of microsporidians cause new taxonomical troubles. At the present time it is difficult to create a clear hypothesis concerning the phylogeny and evolution of Microsporidia. Most likely they are representatives of a new kingdom of Eukaryota. Existing problems will not be dissolved until new detailed data concerning the new and common species are obtained.

Animals↗