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At least 109 records · Page 6Linked to original sources
PubMed1993

Retrobronchial vertical vein in totally anomalous pulmonary venous connection to the innominate vein and its specific occurrence in right isomerism.

Recently, a case of right isomerism with totally anomalous pulmonary venous connection (TAPVC) to the innominate vein through a vertical vein that ascended in the mediastinum posterior to the left-sided main bronchus was encountered. This retrobronchial vertical vein that has not been described previously in patients with TAPVC to the innominate vein prompted the performance of a retrospective analysis of 44 cases with TAPVC to the innominate vein in which angiography had been performed. The 44 cases consisted of 36 patients with situs solitus, 7 with right isomerism, and 1 with left isomerism. The spatial relation of the vertical vein to the adjacent pulmonary artery and main bronchus could be defined in 41 cases. The vertical vein was retrobronchial in 4 of 5 cases with right isomerism in which the location of the vertical vein could be defined with certainty. No case with situs solitus or left isomerism was associated with a retrobronchial vertical vein. In all 4 patients with a retrobronchial vertical vein, angiographic evidence of obstruction of pulmonary venous drainage was present, and was due to an extrinsic bronchial compression in 2 and to an intrinsic narrowing of the vertical vein in 2.

Abnormalities, Multiple↗
PubMed1992

Total anomalous pulmonary venous connection in adults. Long-term follow-up.

Between 1961 and 1989, 19 patients with total anomalous pulmonary venous connection underwent surgical correction. Ages ranged from 18 to 38 years (mean 26.2 +/- 6.5 years). The anatomic variants included 10 patients with total anomalous pulmonary venous connection to the vertical vein, 6 patients with total anomalous pulmonary venous connection to the coronary sinus, and 2 with total anomalous pulmonary venous connection directly to the right atrium. The last patient had mixed connection to the coronary sinus and left vertical vein. Two patients died, one because of left atrial rupture and another of low cardiac output. Long-term follow-up after surgical repair ranged from 2 to 24 years (mean 7 +/- 6.2 standard deviation). Preoperative disability, assessed according to New York Heart Association criteria, showed 12 patients in functional class II and seven in class III. After treatment, 16 patients were in class I and one in class II (p less than 0.001). Echocardiographic evaluation of six patients revealed in all a normal left ventricular ejection fraction; the diastolic function was also normal except in one patient. The postoperative evaluation of the pulmonary arterial systolic pressure performed by both Doppler echocardiography and right cardiac catheterization in 14 patients showed a significant reduction of the mean pulmonary arterial systolic pressure from 51.1 +/- 3.4 to 37.4 +/- 14.4 mm Hg (p less than 0.01). The remaining three patients evaluated in the follow-up period only by clinical examination are in New York Heart Association functional class I. The anatomic characteristics of our patients were responsible for the long-term outcome without correction. Surgical treatment of older patients can be performed with satisfactory results and excellent long-term survival.

Adult↗
PubMed1991

Cat pontine omnipause neurons: direct inhibitory connection with Forel's field burst neurons participating in the genesis of vertical saccades.

This study investigates synaptic connections of omnipause neurons (OPNs) in the midline pontine tegmentum with vertical medium-lead burst neurons (BNs) in the Forel's field H (FFH), using the microstimulation and spike-triggered averaging techniques in chronically prepared alert cats. OPNs on both sides were antidromically activated by microstimulation at the recording sites of the BNs. Systematic tracking with the stimulating microelectrode revealed indications of profuse axonal branching of OPNs within the BN area. Antidromic spikes of the BNs evoked from the oculomotor nucleus and spike bursts of the BNs associated with saccades were suppressed by OPN area microstimulation. Averaged field potentials in the BN area triggered by spikes of OPNs showed monosynaptic positive waves. These results all but confirm the existence of direct inhibitory synaptic connections of OPNs with the BNs in the FFH. The role of OPNs in the genesis of vertical saccades was also discussed.

Animals↗
PubMed1988

Echo Doppler detection of external compression of the vertical vein causing obstruction in total anomalous pulmonary venous connection.

External obstruction of the pulmonary venous return was detected by two-dimensional (2-D) and pulsed Doppler echocardiography and was confirmed by angiography and at surgery in two infants with isolated supracardiac total anomalous pulmonary venous connection (TAPVC) to the left vertical vein. In both infants, the left vertical vein ascended behind the left pulmonary artery and anterior to the left main stem bronchus. This arrangement produces mechanical obstruction to both vertical vein flow and pulmonary venous drainage. Early detection and surgical correction of obstructed pulmonary venous return are necessary to prevent severe right-sided heart failure and death. Doppler echocardiography is recommended when evaluating infants with TAPVC for possible anatomic or mechanical obstruction to pulmonary venous return.

Echocardiography, Doppler↗
PubMed1997

Vertical facial skeletal dysplasias: the oral surgical connection.

Oral surgery can open new vistas of treatment for patients with vertical abnormalities of the face, jaw, and teeth. An interdisciplinary approach is critical, however, incorporating the insights and skills of restorative, orthodontic, periodontal and surgical practitioners working together as a team. A complete diagnosis is the key to any successful treatment plan. Because surgery is instantaneous and relatively irreversible, the treatment team needs to be aware of the impact of surgical repositioning of the maxilla and mandible on the other treatment modalities, so the ultimate prosthetic objectives for the patient may be facilitated and not hindered. The craniofacial complex is more adaptable to vertical changes than is often realized. When a correct "palate" of therapies is chosen, the desired results can be achieved despite the complexities of symptoms and treatment. A desirable result must include optimum function, stability, and facial harmony.

Age Factors↗
PubMed2005

Fate of the unligated vertical vein after repair of supracardiac anomalous pulmonary venous connection.

OBJECTIVE: To determine the fate of the unligated vertical vein after repair of isolated supracardiac total anomalous pulmonary venous connection (TAPVC). METHODS: We reviewed the outcome of 28 patients who were diagnosed to have isolated supracardiac TAPVC and determined the fate of the unligated vertical vein. RESULTS: Of the 28 patients, four died before surgery. The remaining 24 patients underwent surgical correction of TAPVC with (n = 5) or without (n = 19) ligation of vertical vein at a median age of 20 days (range: 1-574 days). There were no significant differences in age, weight, presence of pulmonary venous obstruction, need for preoperative inotropic and ventilatory support, cardiopulmonary bypass duration, postoperative pulmonary hypertensive crisis and requirement of peritoneal dialysis between patients with and those without vertical vein ligation. The in-hospital surgical mortality was 50% (12/24), with 83% (10/12) of deaths occurring before 1990. Patients who died after surgery were significantly younger (median age: 5.5 days vs 37 days, P = 0.005), lighter (3.3 +/- 0.5 kg vs 3.9 +/- 0.6 kg, P = 0.016), more likely to have pulmonary venous obstruction preoperatively (75% vs 12%, P = 0.039) and have undergone surgery before 1990 (83% vs 33%, P = 0.036). The 12 survivors were followed up for a median of 4.7 years (range: 2.3-18.1 years), 10 of whom had their vertical vein unligated. The vertical vein remained patent in five (50%) patients, while stenosis of pulmonary venous anastomosis was only present in one patient. Of these five patients, three had subsequently undergone surgical ligation of the vertical vein to eliminate a large left-to-right shunt. CONCLUSIONS: Patency of the unligated vertical vein is common after the repair of supracardiac TAPVC, even in the absence of pulmonary venous obstruction. The degree of left-to-right shunt through the patent vertical vein may be so significant as to warrant surgical ligation.

Adolescent↗
PubMed1989

Direct inhibitory synaptic connections of pontine omnipause neurons with burst neurons in Forel's field H related to vertical saccades in the cat.

This study investigated synaptic connections of omnipause neurons (OPNs) in the midline pontine tegmentum with medium-lead burst neurons (BNs) in Forel's field H (FFH), using the spike-triggered averaging technique in chronically prepared alert cats. OPNs were identified behaviorally by tonic firing during the intersaccadic period, whereas medium-lead BNs were identified by spike bursts during upward or downward saccades. A positive shift of field potential in the BN area, associated with suppression of the BNs' bursts, was observed during tonic firing of OPNs and during microstimulation in the OPN area. Averaging of BN area field potentials triggered by spikes of single OPNs on both sides, which were antidromically evoked from the BN area, revealed positive waves with monosynaptic latencies. These results strongly suggest that OPNs on both sides make direct inhibitory synaptic connections with vertical eye movement-related medium-lead BNs in the FFH.

Action Potentials↗
PubMed1988

A new local feedback model of the saccadic burst generator.

1. To accommodate the finding that the superior colliculus is an important input to the brain stem pathways that generate saccades (the saccadic burst generator), a new model of the burst generator is proposed. Unlike the model of Robinson (61) from which it was derived, the model attempts to match a neural replica of change in eye position, which is the output of the burst generator, to a neural replica of change in target position, which is the output of the colliculus and the input to the model. 2. The elements of the model correspond to neurons known or thought to be associated with the actual primate saccadic burst generator and are mostly connected together in accord with the results of anatomical and physiological experiments. 3. The model was simulated on a digital computer to compare its behavior with that of the actual burst generator under normal and experimental conditions. Simulated peak burst frequency and saccade duration matched that obtained from monkey excitatory burst neurons and inhibitory burst neurons for saccades up to 15 degrees but did not match at larger sizes; stimulation of the omnipause neurons caused an interruption of the saccade, and the saccade resumed at the end of stimulation as in actual data; the model can generate the abnormally long-duration saccades seen under decreased alertness or various pathologies by changing the burst generator inputs and without having to change any properties of the neurons themselves or their connections; a simulated horizontal and vertical burst generator pair connected only through the omnipause neurons can generate realistic oblique saccades. 4. The implications of the model for higher-order control of the saccadic burst generator are discussed.

Efferent Pathways↗
PubMed1998

A map of the protein space--an automatic hierarchical classification of all protein sequences.

We investigate the space of all protein sequences. We combine the standard measures of similarity (SW, FASTA, BLAST), to associate with each sequence an exhaustive list of neighboring sequences. These lists induce a (weighted directed) graph whose vertices are the sequences. The weight of an edge connecting two sequences represents their degree of similarity. This graph encodes much of the fundamental properties of the sequence space. We look for clusters of related proteins in this graph. These clusters correspond to strongly connected sets of vertices. Two main ideas underlie our work: i) Interesting homologies among proteins can be deduced by transitivity. ii) Transitivity should be applied restrictively in order to prevent unrelated proteins from clustering together. Our analysis starts from a very conservative classification, based on very significant similarities, that has many classes. Subsequently, classes are merged to include less significant similarities. Merging is performed via a novel two phase algorithm. First, the algorithm identifies groups of possibly related clusters (based on transitivity and strong connectivity) using local considerations, and merges them. Then, a global test is applied to identify nuclei of strong relationships within these groups of clusters, and the classification is refined accordingly. This process takes place at varying thresholds of statistical significance, where at each step the algorithm is applied on the classes of the previous classification, to obtain the next one, at the more permissive threshold. Consequently, a hierarchical organization of all proteins is obtained. The resulting classification splits the space of all protein sequences into well defined groups of proteins. The results show that the automatically induced sets of proteins are closely correlated with natural biological families and super families. The hierarchical organization reveals finer sub-families that make up known families of proteins as well as many interesting relations between protein families. The hierarchical organization proposed may be considered as the first map of the space of all protein sequences. An interactive web site including the results of our analysis has been constructed, and is now accessible through http:/(/)www.protomap.cs.huji.ac.il

Algorithms↗
PubMed1995

Epileptiform activity in the guinea-pig neocortical slice spreads preferentially along supragranular layers--recordings with voltage-sensitive dyes.

The spread of epileptiform activity was monitored in guinea-pig neocortical slices by the use of a voltage-sensitive dye (RH795) and a fast optical recording technique. Epileptiform activity induced by bicuculline methiodide (10-20 microM) and single-pulse stimulation spread from the stimulation site in layer I or in the white matter across most of the slice. Different lesions were made in the slice in order to specify the neuronal connections used for spread in the horizontal direction. In the slice, intracortical connections are necessary for the spread of epileptiform activity, as shown by vertical cuts through all cortical layers but sparing the white matter. Horizontal connections were interrupted by cuts parallel to the axis of pyramidal neurons through either supragranular or infragranular layers. Vertical connections were interrupted by cuts perpendicular to the axis of pyramidal neurons separating supragranular and infragranular layers. Spread of epileptiform activity in the horizontal direction was not hindered by horizontal cuts. Vertical cuts through infragranular layers also did not hinder the spread of epileptiform activity. In contrast, vertical cuts through supragranular layers either abolished completely (nine slices) or delayed significantly (ten slices) the spread of epileptiform activity. The mean delay at the supragranular lesion was 44 ms in layer III and 30 ms in layer V; at the infragranular lesion the mean delay was 2 ms in layer III and 6 ms in layer V. Also, with horizontal cuts, in three out of five slices the velocity of spread was significantly lower in infragranular as compared to supragranular layers. It is concluded that both supra- and infragranular layers if isolated possess the ability to initiate and propagate epileptiform activity independently. However, in the intact slice the influence of the supragranular networks on initiation and propagation of epileptiform activity appears to dominate.

Animals↗
PubMed1991

Analysis of soft tissue tumors by an attributed minimum spanning tree.

Histologic slides of 22 soft tissue tumors (9 malignant fibrous histiocytoma, 8 fibrosarcoma, 2 rhabdomyosarcoma, 2 osteosarcoma, 1 Askin tumor) were Feulgen stained. Using an automated image analyzing system (Cambridge 570) at low magnification (25x), the tumor cell nuclei were segmented. The geometrical center of the nuclei was considered the vertex. A basic graph was constructed according to the neighborhood condition of O'Callaghan. Neighboring tumor cell nuclei were visualized by connecting edges. Several features of tumor cell nuclei were measured, including area, surface, major and minor axis of best fitting ellipsis and extinction (DNA content). Nuclear features are attributed to the vertices. The differences, or "distances," between features of connected vertices are attributed to the corresponding edges, which are dependent on the attributes. Thus, different minimum spanning trees (MST) result. Each MST can be decomposed into clusters using a suitable decomposition function on the edges, which rejects an edge if its attributes differ from the mean of the attributed values of surrounding edges more than a neighbor dependent bound (lower limit). Taking into account the length and other attributes of edges (e.g., differences in orientation of the major axis), clusters of different nuclear orientation can be detected. A cluster tree can be constructed by defining the geometric center of a cluster as a new vertex, and by computing the neighborhood of the cluster vertices. The result is an attributed MST containing characteristic structural properties of the image (in cases of sarcomatous tumors, local orientation of tumor cell nuclei and local DNA abnormalities).

Cell Nucleus↗
PubMed1996

Multiple matching of features in simple stereograms.

Simple stereograms are used to show that the binocular matching of closely spaced vertical lines can be changed by horizontally connecting some of the vertical lines. The matching that is seen can be gradually changed by incremental modifications to simple visual quantities like the luminance contrast of a local region, or the density of the connecting horizontal lines. For some values of these visual quantities the depth seen is unstable which suggests that the mechanisms responsible for resolving matching ambiguities might be intrinsically dynamic. These changes in binocular matching can also be used to show a hysteresis-like effect in stereopsis. Many of the constraints like ordering, cohesivity, and uniqueness often used in algorithms for resolving ambiguities are perhaps too limiting to allow either such dynamics or the processing of transparent or partially occluded surfaces.

Adult↗
PubMed1979

Significance of free-dorsiflexion of the toes in walking.

Dissection reveals that the ball of the foot contains a connective tissue framework with transverse, vertical, and sagittal fibers, all connecting the skin with the proximal phalanges of the toes. Dorsiflexion of the toes tightens the framework and thereby restricts passive movements of the skin, enabling shear forces to be transferred to the skeleton. An electromechanical oscillator was constructed that applied oscillatory shear forces of constant amplitude (+/- 0.2 N) to the skin and at the same time measured the resulting motions. It was found that the toes should be dorsiflexed by 35--40 degrees to restrict skin mobility to 50 per cent and by 50 degrees to restrict it maximally. The results were compared to actual dorsiflexions of toes during walking. These dorsiflexions were measured on slow motion film and with still pictures with light tracks formed by light emitting diodes. Maximal dorsiflexion during push off was found to be 60 degrees for feet walking without shoes, 45--50 degrees for feet walking in soft shoes, and 25--30 degrees for feet walking in a stiff shoe of the minus-heel type. Dorsiflexion was further found significant for arch support and for the mechanics of the forefoot during push-off.

Biomechanical Phenomena↗
PubMed1996

Overlapping and nonoverlapping cortical projections to cortex of the superior temporal sulcus in the rhesus monkey: double anterograde tracer studies.

To examine how fibers from functionally distinct cortical zones interrelate within their target areas of the superior temporal sulcus (STS) in the rhesus monkey, separate anterograde tracers were injected in two different regions of the same hemisphere known to project to the STS. Paired injections were placed in dorsal prearcuate cortex and the caudal inferior parietal lobule (IPL), interconnected regions that are part of a hypothesized distributed network concerned with visuospatial analysis or directed attention; in a presumed auditory region of the superior temporal gyrus (STG) and in extrastriate visual cortex, the caudal IPL and lower rim of the intraparietal sulcus; and in dorsal prearcuate cortex and the STG. Overlapping and nonoverlapping projections were then examined in STS visual and polysensory areas. Prefrontal and parietal fibers directly overlapped extensively in area MST and all subdivisions of presumed polysensory cortex (areas TPOc, TPOi, and TPOr), although nonoverlapping connections were also found. Although STG and IPL fibers targeted all TPO subdivisions, connections were to nonoverlapping, but often adjacent, columns. Paired prefrontal and STG injections revealed largely nonoverlapping vertical columns of connections but substantial overlap within layers VI and I or areas TPOc and TPOi. The findings suggest that area TPO contains differently connected modules that may maintain at least initial segregation of visual versus auditory inputs. Other modules within area TPO receive directly converging input from the posterior parietal and the prefrontal cortices and may participate in a distributed cortical network concerned with visuospatial functions.

Animals↗
PubMed2006

Growth model for complex networks with hierarchical and modular structures.

A hierarchical and modular network model is suggested by adding a growth rule along with the preferential attachment (PA) rule into Motter's modeling procedure. The proposed model has an increasing number of vertices but a fixed number of modules and hierarchical levels. The vertices form lowest-level modules which in turn constitute higher-level modules hierarchically. The creation of connections between two vertices in a single module or in two different modules of the same level obeys the PA rule. The structural characteristics of this model are investigated analytically and numerically. The results show that the degree distribution, the module size distribution, and the clustering function of the model possess a power-law property which is similar to that in many real-world networks. The model is then used to predict the growth trends of real-world networks with modular and hierarchical structures. By comparing this model with those real-world networks, an interesting conclusion is found: that many real-world networks are in their early stages of development, and when the growth time is large enough, the modules and levels of the networks will be ultimately merged.

Journal Article↗
PubMed2003

Distribution of the amplitude of the self-oscillation of the electrical potential difference observed in an organic phase of a water-oil-water liquid membrane system.

The electrical potential differences were measured at various points in an organic phase of a water-oil-water liquid membrane system in which self-oscillations of an electrical potential difference occurred across a three-phases-liquid membrane by using an H-shaped cell. The electrical potential difference oscillated in the direction through the two aqueous phases, but not in its vertical direction. The amplitude of the self-oscillation greatly changed around the place where the horizontal tube was connected to the vertical tube, which had no surfactant.

Journal Article↗
PubMed1967

Studies of spermatogenesis in the hepaticae. I. Ultrastructure of the vierergruppe in Marchantia.

Spermatids of the liverwort Marchantia polymorpha were shown by analysis of thin-sections to contain a four-layered organelle, the Vierergruppe, lying between the flagellar bases above and a subjacent mitochondrial body. The uppermost layer consists of parallel tubules structurally similar to those of the axoneme. Some of the tubules extend beyond the four-layered region to form a long ribbon-like appendage. The second layer consists of low, vertical, membranous fins connected by numerous short links to the tubules above. The third layer, limited above and below by two horizontal membranes, consists of vertical partitions, apparently continuous with the fins. The fourth and lowermost layer consists of narrow parallel tubules aligned beneath alternate partitions. The long axes of the lower three layers are parallel to each other and lie at an angle of 48 degrees to the tubule axis of the uppermost stratum. A graphic representation of a three-dimensional scale model interpreting organelle structure is given. The Vierergruppe supersedes Dreiergruppe interpretation in most if not all of the bryophytes studied to date.

Cell Division↗