An unusual presentation of constriction band syndrome

Congenital constriction band syndrome is a rare entity with a wide spectrum of associated congenital anomalies. Review of the pathogenesis and an unusual case of constriction band syndrome in a newborn are presented. Surgical excision of the deformity and the band was performed within the first week of life. There were no vascular or neural structures within the excised tissue, and there were no other associated anomalies other than dextrocardia and an equinovarus deformity of the foot. The wound was closed primarily without the need for Z-plasties. This alternative method of treatment can be considered in such unusual locations of constriction band syndromes.     

Congenital skin tube pedicle associated with the constriction band syndrome.

A very rare case of congenital skin tube pedicle with congenital constriction band syndrome was presented. Only one report concerning this bizarre abnormality could be found in the available literature, and no consideration of its etiology has previously been published. In our case, the skin tube was accompanied by the congenital constriction band syndrome, the cause of which is generally thought to be external factors. Thus the etiology of the congenital skin tube pedicle might be the peeling and rolling of a strip of the fetal skin by external force.     

Comparison of the Giemsa C-Band karyotypes and the relationships of Allium cepa,A. fistulosum and A. galanthum

Giemsa C-band staining of somatic chromosomes in Allium cepa, A. cepa cv. Shallot, A. fistulosum and A. galanthum shows that these four taxa are characterised by all chromosomes having one band at each telomere, except chromosome arms with satellites, in which case the band is proximal to the nucleolar constriction. This similarity is correlated with common morphological characteristics and an ability of the three species to hybridize with one another, indicating that they have a close genetic relationship. The results indicate that Giemsa C-bands are evolutionarily conservative in this group and provide a useful criterion for determining relationships.     

Congenital constriction band syndrome. Pathophysiology and treatment.

The clinical manifestations of 88 children with congenital constriction band syndrome involvement of the hand were reviewed. Seventy-five of these children had evidence of digital or limb amputations, with 235 upper limb amputations and 138 lower limb amputations. In the hand, digital amputations were most common in the index, middle, and ring fingers, whereas in the foot, amputations of the hallux were most often noted. Band indentation was often present at multiple levels. Proximal bands may be associated with neural compression. Syndactyly was invariably associated with a proximal interdigital sinus or cleft and was frequently associated with distal amputation. Examination of a 27-week gestation stillborn specimen having manifestations of congenital constriction band syndrome demonstrated the intrauterine biologic response to band constriction. The variable clinical manifestations of congenital constriction band syndrome can best be explained as the response of the growing, embryologically defined limb to intrauterine deformation or band-induced compression and ischemia.     

The concurrence of ring constrictions in Adams-Oliver syndrome: additional evidence for vascular disruption as common pathogenetic mechanism.

We report on a girl with congenital scalp and acral reduction limb defects, consistent with the diagnosis of Adams-Oliver syndrome. The presence of constriction rings makes the limb anomalies in this case similar to those seen in the amniotic band disruption sequence. Vascular disruption--with or without secondary amniotic rupture--may be responsible for the observed anomalies. Therefore we believe that the present observation adds further evidence for the hypothesis that the Adams-Oliver syndrome is a vascular disruption sequence.     

Amniogenic band anomalies in a fifth-month fetus and in a newborn from maternal oophorectomy during early pregnancy

A fifth-month fetus and a newborn with amniogenic band anomalies were examined at autopsy. Both specimens were obtained from women who had undergone oophorectomy during early pregnancy. The dead male fetus was aborted spontaneously, and had a micrognathia, a right club foot, and a constriction ring on the left lower leg. The left fingers 2, 3, and 4 were attached to the placenta by a fibrous string. No internal anomaly was noted. In the other case, a male newborn was delivered at the 39th week of gestation and had an agenesis of the calvarium, a cleft lip with palate, an amputation of the right toe, and constriction rings on right fingers 3 and 4 and left finger 3. The placenta was attached to the left temporooccipital region of the head by a fibrous string. Also present was an atrial septum defect and a horseshoe kidney. Possible etiology is discussed in relation to the "amniogenic bands" hypotheses.     

Effects of vibration on steady flow downstream of a stenosis

A physical model was used to test the effects of vibrations on the position of transition to turbulence (zt) downstream of a constriction. Constrictions were inserted in a length of clear plastic (Tygon) tubing and vibrated. Water was the fluid medium and flow was visualized with India ink. The frequency and velocity of vibration were monitored. For a given constriction and flow velocity, there was a band of frequencies which caused zt to move upstream. This band corresponded to frequencies of flow disturbances as measured with a hot-film anemometer without vibration. Both flow-visualization and hot-film frequencies were correlated via a Strouhal number to the Reynolds number and contraction ratio of the flow. Values of zt decreased with increasing vibration amplitude. The critical Reynolds number for turbulence was also decreased by vibration. These results are of importance in the diagnosis of vascular disease and the design of physical models of stenotic flows.     

The dynamics of cell constriction during division

The approximate equation is derived for the rate of constriction of a dividing cell, describing the phenomenon from its early stages. The equation previously derived by G. Young for the case when the constriction has already considerably progressed is obtained as a limiting case.     

Molecular topography of the secondary constriction region (qh) of human chromosome 9 with an unusual euchromatic band.

Heterochromatin confined to pericentromeric (c) and secondary constriction (qh) regions plays a major role in morphological variation of chromosome 9, because of its size and affinity for pericentric inversion. Consequently, pairing at pachytene may lead to some disturbances between homologous chromosomes having such extreme variations and may result in abnormalities involving bands adjacent to the qh region. We encountered such a case, where a G-positive band has originated de novo, suggesting a maternal origin from the chromosome 9 that has had a complete pericentric inversion. In previously reported cases, the presence of an extra G-positive band within the 9qh region has been familial, and in the majority of those cases it was not associated with any clinical consequences. Therefore, this anomaly has been referred to as a "rare" variant. The qh region consists of a mixture of various tandemly repeated DNA sequences, and routine banding techniques have failed to characterize the origin of this extra genetic material. By the chromosome in situ suppression hybridization technique using whole chromosome paint, the probe annealed with the extra G-band, suggesting a euchromatic origin from chromosome 9, presumably band p12. By the fluorescence in situ hybridization technique using alpha- and beta-satellite probes, the dicentric nature was further revealed, supporting the concept of unequal crossing-over during maternal meiosis I, which could account for a duplication of the h region. The G-positive band most likely became genetically inert when it was sandwiched between two blocks of heterochromatin, resulting in a phenotypically normal child. Therefore, an earlier hypothesis, suggesting its origin from heterochromatin through so-called euchromatinization, is refuted here.(ABSTRACT TRUNCATED AT 250 WORDS)     

Computational fluid dynamic analysis of flow velocity waveform notching in umbilical arteries

Umbilical artery Doppler velocimetry waveform notching has long been associated with umbilical cord abnormalities, such as distortion, torsion, and/or compression (i.e., constriction). The physical mechanism by which the notching occurs has not been elucidated. Flow velocity waveforms (FVWs) from two-dimensional pulsatile flows in a constricted channel approximating a compressed umbilical cord are analyzed, leading to a clear relationship between the notching and the constriction. Two flows with an asymmetric, semi-elliptical constriction are computed using a stabilized finite-element method. In one case, the constriction blocks 75% of the flow passage, and in the other the constriction blocks 85%. Channel width and prescribed flow rates at the channel inflow are consistent with typical cord diameters and flow rates reported in the literature. Computational results indicate that waveform notching is caused by flow separation induced by the constriction, giving rise to a vortex (core) wave and associated eddies. Notching in FVWs based on centerline velocity (centerline FVW) is directly related to the passage of an eddy over the point of measurement on the centerline. Notching in FVWs based on maximum cross-sectional velocity (envelope FVW) is directly related to acceleration and deceleration of the fluid along the vortex wave. Results show that notching in envelope FVW is not present in flows with less than a 75% constriction. Furthermore, notching disappears as the vortex wave is attenuated at distances downstream of the constriction. In the flows with 75 and 85% constriction, notching of the envelope FVW disappears at ～3.8 and ～4.3 cm (respectively) downstream of the constriction. These results are of significant medical importance, given that envelope FVW is typically measured by commercial Doppler systems.     

Expression and function of the homoeotic genes Antennapedia and Sex combs reduced in the embryonic midgut of Drosophila

Drosophila homoeotic genes control the formation of external morphological features of the embryo and adult, and in addition affect differentiation of the nervous system. Here we describe the morphogenetic events in the midgut that are controlled by the homoeotic genes Sex combs reduced (Scr) and Antennapedia (Antp). The midgut is composed of two cell layers, an inner endoderm and an outer visceral mesoderm that surround the yolk. Scr and Antp are expressed in the visceral mesoderm but not in the endoderm. The two genes are required for different aspects of the midgut morphogenesis. In Scr null mutant embryos the gastric caeca fail to form. Scr is expressed in the visceral mesoderm cells posterior to the primordia of the gastric caeca and appears to be indirectly required for the formation of the caeca. Antp is expressed in visceral mesoderm cells that overlie a part of the midgut where a constriction will form, and Antp null mutant embryos fail to form this constriction. An ultrastructural analysis of the midgut reveals that the visceral mesoderm imposes the constriction on the endoderm and the yolk. The mesodermal tissue contracts within the constriction and thereby penetrates the layer of the midgut endoderm. Microtubules participate in the morphological changes of the visceral mesoderm cells. The analysis of the expression of Scr in Antp mutant embryos revealed a case of tissue-specific regulation of Scr expression by Antp. In the epidermis, Antp has been shown to negatively regulate Scr, but it positively regulates Scr in the visceral mesoderm.     

First prenatally detected small supernumerary neocentromeric derivative chromosome 13 resulting in a non-mosaic partial tetrasomy 13q

Neocentromeres are functional centromeres located in non-centromeric euchromatic regions of chromosomes. The formation of neocentromeres results in conferring mitotic stability to chromosome fragments that do not contain centromeric alpha satellite DNA. We present a report of a prenatal diagnosis referred to cytogenetic studies due to ultrasound malformations such as large cisterna magna, no renal differentiation, hypotelorism and ventriculomegaly. Cytogenetic analysis of GTG-banded chromosomes from amniotic fluid cells and fetal blood cells revealed a de novo small supernumerary marker chromosome. Molecular cytogenetic studies using fluorescence in situ hybridization and comparative genomic hybridization showed this marker to be an inverted duplication of the distal portion of chromosome 13q which did not contain detectable alpha satellite DNA. The neocentromeric constriction was located at band 13q31. The presence of a functional neocentromere on this marker chromosome was confirmed by immunofluorescence with antibodies to centromere protein-C. The anatomopathologic study revealed a female fetus with facial dysmorphisms, low set ears and renal dysplasia. Ten small supernumerary neocentromeric chromosomes originating from the distal region of chromosome 13q have been reported to date. There are only three additional cases described with the location of the neocentromere in band 13q31. This is the first reported case detected prenatally.     

The chromosomal passenger complex and centralspindlin independently contribute to contractile ring assembly

The chromosomal passenger complex (CPC) and centralspindlin are conserved cytokinesis regulators that localize to the spindle midzone, which forms between the separating chromosomes. Previous work placed the CPC and centralspindlin in a linear pathway that governs midzone formation. Using Caenorhabditis elegans embryos, we test whether there is a similar linear relationship between centralspindlin and the CPC in contractile ring constriction during cytokinesis. We show that simultaneous inhibition of the CPC kinase Aurora B(AIR-2) and the centralspindlin component MKLP1(ZEN-4) causes an additive constriction defect. Consistent with distinct roles for the proteins, inhibition of filamentous septin guanosine triphosphatases alleviates constriction defects in Aurora B(AIR-2)-inhibited embryos, whereas inhibition of Rac does so in MKLP1(ZEN-4)-inhibited embryos. Centralspindlin and the CPC are not required to enrich ring proteins at the cell equator but instead regulate formation of a compact mature ring. Therefore, in contrast to the linear midzone assembly pathway, centralspindlin and the CPC make independent contributions to control transformation of the sheet-like equatorial band into a ribbon-like contractile ring at the furrow tip.     

Plastid apportionment and preprophase microtubule bands in monoplastidic root meristem cells ofIsoetes andSelaginella

Summary Ultrastructural observations on monoplastidic root tip cells ofIsoetes andSelaginella demonstrate two important phenomena associated with preprophasic preparation for mitotic cell division, 1. the preprophase band and 2. precise orientation of the dividing plastid relative to the preprophase band. Both of these phenomena accurately predict the future plane of cell division. The plastid divides in a plane parallel to the spindle and each cell inherits a single plastid which caps the telophase nucleus. When succesive transverse divisions occur, the plastid migrates prior to prophase from a position near an old transverse wall to a lateral position in the cell. The plastid is oriented with its median constriction precisely intersected by the plane of the preprophase band. When a longitudinal division follows a transverse division, the plastid remains in its position adjacent to an old transverse wall where it is bisected by the plane of the longitudinally oriented preprophase band microtubules.     

Microtubules as key cytoskeletal elements in cellular transport and shape changes: their expected responses to space environments

Application of reference standard reagents to alternatively depolymerize or stabilize microtubules in a cell that undergoes very regular cytoskeleton-dependent shape changes provides a model system in which some expected components of the environments of spacecraft and space can be tested on Earth for their effects on the cytoskeleton. The fertilized eggs of Ilyanassa obsoleta undergo polar lobe formation by repeated, dramatic, constriction and relaxation of a microfilamentous band localized in the cortical cytoplasm and activated by microtubules.     

Mathematical biophysics of cell division

The new fundamental equation, based on the principle of maximum energy exchange, is applied to the case of elongation and constriction of a cell. A simple case is treated as an illustration, and it is shown that the elongation curves thus obtained are of the same character as in the old theory.     

Karyotypes, chromosome bands and genome size variation in New Zealand endemic gymnosperms

Karyotype studies on 20 taxa of gymnosperms endemic to New Zealand show a wide diversity of chromosome number and form. Fluorochrome banding with DAPI and CMA reveals a depauperate pattern of bands with CMA and no reliable banding with DAPI. Characteristically one pair of chromosomes shows a prominent CMA band, which may or may not be associated with a secondary constriction. A band size polymorphism was observed in all plants ofDacrycarpus dacrydioides, irrespective of the sex of the plant. Measurements of genome size by flow cytometry show a range of values from 12.3 pg to 40.0 pg DNA per 2C nucleus. Intraspecific variation in genome size was observed inManoao colensoi.     

Three cases of minor chromosomal aberrations discovered by prenatal chromosome determination

Summary A case of pronounced secondary constriction of a chromosome belonging to pair No. 9, a case of deletion of the short arms of one of the chromosomes in pair No. 13, and a case of partial trisomy of the distal portion of a chromosome in pair No. 14 were discovered by prenatal chromosome determination. Analysis of the parents' karyotypes enabled the clinical importance of the three different chromosomal aberrations to be elucidated.     

Two dicentric Y isochromosomes,one without the Yqh heterochromatic segment

Summary Two women with primary amenorrhoea and few other stigmata of Turner's syndrome were found to be chromosome mosaics: 45,X/46,X,idic(Y). In Case 1, the dicentric isochromosome Y was found to have a long-arm breakpoint of formation. This structure was interpreted as containing two Y short arms and centromeres separated by a region derived from the proximal Y long arm. One of the centromeres in the Case 1 —idic(Y) was suppressed in 80% of cells in blood, and in these cells it appeared as a regular Y-shaped chromosome. In Case 2 the idic(Y) was derived by a short-arm breakpoint of formation. In all the dicentrics of this case with one primary constriction (functional monocentrics) there was a single Cd band. In the 10% of dicentrics with two primary constrictions, there were two Cd bands. It is argued that the instability of sex isochromosomes is due to this functional dicentricity in some cells. These cases are compared with 42 other Y isochromosomes with various short- and long-arm breakpoints of formation. It is suggested that some of the nonheterochromatic, nonfluorescent Y chromosomes previously reported may be explained as dicentric i(Y) with proximal long-arm breakpoints of formation and one suppressed centromere.     

Role of the endothelium in the development of the contractile reactions of vascular smooth muscle during decreased oxygenation

Noradrenaline-preactivated vascular smooth muscles (VSM) of the rat thoracic aorta showed two-phase reactions in response to decreased oxygenation: significant relaxation was preceded by transient constriction. When the endothelium was removed only VSM relaxation phase was retained, with no constriction observed. The data obtained suggest an endothelium-dependent nature of VSM constriction reaction to hypoxia, in contrast to endothelium-independent VSM relaxation. Intracellular calcium is also assumed to play an essential role in the formation of endothelium-dependent constriction VSM reaction to hypoxia.