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At least 199 records · Page 11Linked to original sources

Clinical utility of the simultaneous recording of heart and Korotkoff sounds.

Heart and arterial sounds and murmurs for a sequence of as many as 100 successive beats are recorded on a single print. The apparatus consists of a cathode ray oscilloscope, a Q-wave trigger to release the beam, a vertical axis which is connected to the blood pressure cuff, and an intensity modulation circuit which determines the intensity of the beam at each instant. This arrangement eliminates the baseline and thereby permits the display of low intensity acoustic signals. Data on normal subjects, and patients with various heart diseases are illustrated. Advantages and limitations of the method are discussed.

Adult↗

The cytoskeleton of the apical border of the lateral cells of freshwater mussel gill: structural integration of microtubule and actin filament-based organelles.

The coexistence of densely packed microtubule- and microfilament-based elements in the apex of ciliated epithelial cells, such as the lateral (L) cells of freshwater mussel gill, suggests that with this system it may be possible to define structural connections and interactions that permit integrated cytoskeletal responses to known physiological stimuli. In this study we examine the structure of the L cell apex in detail. The central elements of the elaborate cytoskeleton of the cortex are the basal bodies whose specialized accessory processes are points of integration and the focus of cortical microtubule and microfilament networks. Each basal body supports a cilium and interacts with adjacent basal bodies and with the cell periphery via a dual set of fibre-containing flat trabeculae, both of which are attached to a special organizing centre, the basal foot cap. The distal trabecula is composed of microtubules and the proximal of microfilaments. Connecting the trabeculae, at vertices in the filamentous grids, are core bundles of microfilaments from apical microvilli. In this way, a zig-zag pattern that characterizes microvillar organization at the cell surface is generated. At the cell periphery, the microfilaments from basal foot caps join a peripheral band of microfilaments that underlies the cell border and is associated with four special sites, one in each corner of the cell. Mussel gill epithelial cells contain a polypeptide that resembles actin in its mobility in sodium dodecyl sulphate/10% (w/v) polyacrylamide gels and its affinity for DNase I. Decoration with heavy meromyosin demonstrates that many microfilaments of the L cell apex contain actin, including the microvillar core and peripheral band microfilaments. Actin-associated proteins are also present in these epithelial cells. The actin filaments of the peripheral band are organized to support contraction of the cell border, which would also affect each element of the cortex. This structural complexity, combined with the limited number of modes of interaction between various elements, suggests that the L cell apical cytoskeleton endows the cell with significant positional and morphogenetic information that could be used to compute organellar and cytoskeletal lengths, spacing and changes upon stimulation.

Actins↗

[Total anomalous drainage of the pulmonary veins-- surgical therapy for the infradiaphragmatic and mixed anatomical types].

OBJECTIVE: To study the in-hospital evolution of patients with the infradiaphragmatic and mixed types of total anomalous pulmonary venous drainage (TAPVD), who underwent surgical therapy. METHODS: Of the 65 patients diagnosed with isolated TAPVD and operated on from December 1993 to March 2002, 7 (10.8%) patients with the mixed and infradiaphragmatic forms were retrospectively selected. Their ages ranged from 5 days to 19 months (mean of 7 months), 5 (71.4%) were males, and their clinical diagnosis was established with 2-dimensional echocardiography. Four (57.1%) patients had the mixed form, which was intrinsic obstructive in 1 patient, with mild stenosis of the left inferior vein. The remaining 3 (42.9%) patients had the obstructive infradiaphragmatic form, extrinsic at the level of the diaphragm. All surgeries were performed through median sternotomy with hypothermic extracorporeal circulation, and total circulatory arrest was required in 2 patients. RESULTS: In-hospital death occurred in 1 patient with infradiaphragmatic TAPVD with connection of the inferior vertical vein with the portal vein. The cause of death was related to multisystem organ failure. In 4 (57.1%) patients, the postoperative period was characterized by the presence of low cardiac output and pulmonary hypertension. CONCLUSION: The result of the surgical correction of this anomaly is associated with acceptable morbidity and mortality, depending on early referral and surgery, without progression of the pulmonary vascular hypertension findings.

Diaphragm↗

A biometric guide to prosthetic tooth positioning investigated in subjects with Class II division 2 incisor relationships.

A biometric guide for positioning of the maxillary central incisors in complete dentures is the incisor-incisive papilla distance. This distance was compared in dentate subject with either Class I or Class II/2 incisor relations. Maxillary casts were orientated parallel to the occlusal plane on an xy table, connected to a movable vertical arm. The distance from the posterior edge of the papilla to the labial incisor surface was measured. Results showed a mean difference of 2 mm between the groups, significant at the P < or = 0.001 level, however this distance would not appear to invalidate the conventional biometric guideline of 10 mm.

Adult↗

[Late embryonic development of the vomeronasal complex of the cat (Felis silvestris)].

An examination of 2 feline embryos in different stages of development (overall length 60 and 115 mm respectively) reveals a well developed vomeronasal complex in each case. Jacobson's Organs embedded within the paraseptal cartilage form long blind tubes at the base of the septum nasi. The cartilage is caudally tub-shaped and embraces rostrally completely the organ over a considerable length. In this manner a long, nearly tunnel-like tube is formed which represents a modified form of the original outer bar and which has not been described so far in cats. It stretches rostro-ventrally across the branching region of the paraseptal cartilage as far as the mouth of Jacobson's Organ. The dorsal branch of the cartilago paraseptalis on the other hand forms a vertically oriented strip which connects to the lamina transversalis anterior. The ductus nasopalatinus passing through the palate is laterally supported by a cartilago ductus nasopalatini which rostrally to the mouth of Jacobson's Organ forms a unified element with the ventral branch of the cartilago paraseptalis. In the case of the younger cat embryo, this cartilago ductus nasopalatini is yet weakly developed. The ductus nasopalatini of the embryos studied are in an amazingly retarded state of development. The ductus, which are blocked in the early stages of the embryonic development during secondary palate formation, form predominantly solid strands of epithelium. By dissolving the cemented epithelium, the ductus are open. But even in the case of the older embryo of the cat, this process is not completed yet. The short duct connecting Jacobson's Organ with the ductus nasopalatinus is also still closed in both embryos. Such cemented sections of epithelium of the younger embryo reveals an interesting relation between the ductus nasopalatinus and the ductus nasolacrimalis which so far has not been pointed out for mammals. From the point of view of phylogenetics, the locally specialized vomeronasal complex of cats exhibits all the criteria of a progressive development of characteristics.

Animals↗

[Quantitative analysis of the development and age-related anatomy of the inferior vena cava in human ontogeny].

Periods of intensive changes and phases of a relative stabilization are observed in the inferior vena cava development. By the 4th month of the prenatal period of ontogenesis the inferior vena cava is completely formed and further its general plan of development has no any principle differences. In fetuses and children there is an essential increase of the lumen, length and angle in the inferior vena cava formation. An intensive growth of the transversal section area of the inferior vena cava initial portion in infants is connected with transition to vertical position and an increasing hydrodynamic loading in the mentineed portio of the inferior vena cava. In fetuses, newborns and children up to 12 years of age the inferior vena cava has a high level of formation, that corresponds to position of III--IV lumbar vertebrae. A statistically significant increase in the inferior vena cava parameters is noted in the adolescent period, which result from a general intensive development of the human organism ad its vascular system, in particular. At this age the level of the inferior vena cava formation descends up to the area of the IV--V lumbar vertebrae. Intensive changes in the inferior vena cava size is completed by the end sexual maturation. In the first and second mature ages a phase of a relative stabilization in the inferior vena cava development is noted. In elderly and old ages certain vasodilatation and elongation of the inferior vena cava is observed. Its formation area descends to the level of V lumbar -- I sacral vertebrae. Correlative analysis has proved the main stages in the development of the vessel studied, and the regression equations obtained can be used as an additional method for defining age of the corpse when a forensic medical examination is performed.

Adolescent↗

Mechanical aspects of a Brånemark implant connected to a natural tooth: an in vitro study.

Mechanical in vitro tests of the Brånemark implant disclose that the screw joint which attaches the prosthetic gold cylinder and the transmucosal abutment to the fixture forms a flexible system. This inherent flexibility seems to match well the vertical mobility of a supporting tooth connected to the implant. Calculations of vertical load distribution based on measured flexibility data demonstrate that the forces are shared almost equally between tooth and implant even without taking the flexibility of the surrounding bone or the prosthesis into account. The therapy of a single Brånemark implant connected to a natural tooth should be considered without any additional element of a flexible nature. Mechanical tests and theoretical considerations, however, indicate that the transverse mobility of the connected tooth should be limited and that the attachment of the prosthesis to the tooth should be of a rigid design to avoid gold-screw loosening.

Dental Abutments↗

Enumeration of four-connected three-dimensional nets. I. Conversion of all edges of simple three-connected two-dimensional nets into crankshaft chains.

Various topological approaches to mathematical analysis, classification and enumeration of four-connected three-dimensional (3D) nets are listed. Four-connected 3D nets are being generated systematically by conversion of edges of a vertical stack of congruent three-connected two-dimensional (2D) nets into chains. This paper describes 57 3D nets obtained by converting into crankshaft chains all edges of the simpler 2D nets in the catalog of the Consortium of Theoretical Frameworks. Atomic coordinates are given for distance-least-squares modeling in the highest space group. Nine nets occur in known structures: tridymite, Zn(2)P(2)O(8).organic, aluminophosphates AlPO-5 (International Zeolite Association Structure Commission code AFI), AlPO-8 (AEI), AlPO-11 (AEL), AlPO-25 (ATV), AlPO-41 (AFO), AlPO-54 (VFI) and AlPO-H2 (AHT).

Journal Article↗

The role of bladder biofeedback in the treatment of children with refractory nocturnal enuresis associated with idiopathic detrusor instability and small bladder capacity.

PURPOSE: Not all children with primary nocturnal enuresis, an unstable detrusor and small bladder capacity can be treated successfully with anticholinergics and bladder drill. We report our use of bladder biofeedback in patients who did not respond to 3 months of such treatment. MATERIALS AND METHODS: A total of 24 patients (median age 10.4 years) were studied. For bladder biofeedback a transurethral catheter was placed and connected with a 3-way connector. The bladder was slowly filled through this catheter and the intravesical pressure could be seen on a vertical tube, which was also connected to the transurethral catheter. The perineal bulbar detrusor inhibiting reflex was used in cases of involuntary bladder contraction. During the day patients retained urine as long as possible and completed a micturition chart. RESULTS: Of the 24 patients bed-wetting stopped completely in 17 and decreased in 6, and treatment failed in 1. All patients were followed for at least 6 months after treatment. There were 2 cases of recurrence in the group that was cured. CONCLUSIONS: Intravesical biofeedback can successfully treat patients with refractory primary enuresis associated with unstable detrusor and small bladder capacity.

Adolescent↗

Spatial organization of EEG coherence during listening to consonant and dissonant chords.

Theories of harmony state that the contribution of both sensory and cognitive components is important for musical consonance perception. The aims of the present study were to analyze (a) functional intra- and inter-hemispheric connectivity associated with listening to consonant and dissonant chords using EEG coherence method; (b) relationships between affective responsiveness, sensory aspects of perceived consonance and associated brain connectivity. We identified two lines of inter-hemispheric connectivity in the theta band; one localized anterior being sensitive to consonance and one localized posterior sensitive to dissonance. Stronger right intra-hemispheric connectivity for consonance than dissonance in the theta band was associated with higher pleasantness ratings. The relationship between sensory aspects of perceived consonance and left intra-hemispheric connectivity found in theta-2 was interpreted as processing of vertical harmony without emotional involvement. The stronger connectivity along the axis "left anterior-right posterior" for dissonance than consonance in the alpha-1 band is discussed as a correlate of novelty processing. By introducing a "auditory object dissociation" hypothesis we suggest to extend the present concept of harmony perception. We believe that "auditory object dissociation" is a component of "sensory dissonance."

Acoustic Stimulation↗

Interhemispheric connections of cortical sensory areas in tree shrews.

Interhemispheric connections were studied in tree shrews (Tupaia belangeri) after multiple injections of horseradish peroxidase or horseradish peroxidase conjugated to wheat germ agglutinin into the cortex of one cerebral hemisphere. After an appropriate survival period, the areal pattern of connections was revealed by flattening the other hemisphere, cutting sections parallel to the cortical surface, and staining with tetramethylbenzidine. Architectonic boundaries were identified by using sections stained for myelinated fibers. Labeled cells and axon terminations formed largely overlapping distributions that covaried in density, although labeled cells appeared to be more evenly distributed than labeled terminations. Connections were concentrated along the border of area 17 (V-I) with area 18 (V-II). However, connections also extended as far as 2 mm into area 17 to include cortex representing parts of the visual field 10 degrees or more from the zero vertical meridian. Clusters of dense connections spanned the width of area 18, where they alternated with regions of fewer connections. These clusters roughly corresponded in location to regions with heavier myelination. In the visually responsive temporal cortex, connections were also unevenly distributed. The organization of most of this cortex is not understood, but one subdivision, the temporal dorsal area (TD), has been identified on the basis of reciprocal connections with area 17. The central part of the TD had few interhemispheric connections, while most of the outer border had dense connections. The auditory cortex had dense and patchy connections throughout. The pattern in the primary somatosensory cortex (S-I) varied according to the representation of body parts, so that the cortex related to the forepaw had sparse connections, while connections were dense but uneven over much of the representation of the face, nose, and mouth. A focus of connections was found at the border of the forepaw and face representations, where the myelination of S-I cortex is interrupted. Dense, uneven connections also characterized the second somatosensory area, S-II. The motor cortex was densely connected, with only slightly fewer terminations rostral to the forepaw region of S-I. Other parts of frontal cortex had dense connections. The distribution of cortical connections varied with depth for at least some areas, so that clusters of cells and terminations were found in supragranular layers in S-I, S-II, and TD, while infragranular labeled cells were more evenly distributed.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

Distinct electrical and chemical connectivity maps in the thalamic reticular nucleus: potential roles in synchronization and sensation.

GABAergic neurons of the thalamic reticular nucleus (nRt) provide thalamocortical relay neurons with feedback inhibition that influences sensory processing and thalamocortical rhythm generation. Mutual interactions between reticular neurons coordinate oscillatory activities developed within the network during normal sleep and in absence epilepsy, but the chemical versus electrical nature of these connections and their functional influence remain controversial. Here, we investigated the incidence and spatial extent of intra-nRt connectivity in vitro in horizontal and coronal thalamic slices from rat. Laser scanning photostimulation activated presynaptic nRt cells during patch-clamp recordings of postsynaptic neurons. Photolysis of caged glutamate evoked GABAergic IPSCs and/or depolarizing events (spikelets, mediated via electrical coupling) in a large proportion of neurons, thus indicating connectivity with presynaptic cell(s). Synaptic inputs were organized along the major axis of the nucleus in the same orientation as, but commonly exceeding the extent of, dendritic arborization of the postsynaptic neuron. In the anteroposterior (horizontal) plane, chemical connectivity had higher incidence (60% of recorded neurons vs 40% in vertical plane) and longer spatial extent, whereas in the dorsoventral (vertical) plane, electrical coupling dominated (47% incidence vs 37% in horizontal plane) and was more widely distributed. These data demonstrate that both electrical and chemical synapses are prominent within nRt and suggest different roles for the two types of connections. We thus propose that, along the vertical plane, electrical connectivity will promote coordinated rhythmic activity of sleep and/or thalamocortical epilepsy, whereas along the horizontal plane, chemical connectivity will oppose widespread thalamocortical synchronization and modulate sensory throughput.

Animals↗

The chirality of ground DNA knots and links.

The chirality of ground DNA knots and links is described and characterized in terms of color symmetry groups (CSG), i.e. color symmetry groups I and II, which correspond to topochirality (topological chirality) and topoachirality (topological achirality) which bear an uncanny resemblance to point groups I (proper) and point groups II (improper) used for testing geochirality (geometrical chirality) and geoachirality (geometrical achirality), respectively. By regarding these two crossing modes in mirror images as white and black vertices, DNA knots and links with minimal crossings can be mapped to vertex-bicolored graphs under a working hypothesis that DNA knots and links exist in ground states with minimal energy m0. The color symmetry group of a vertex-bicolored graph G is defined as the set of all permutations and permutation asymmetrizations of the vertices of G that preserve its topology (connectivity), where asymmetrization, denoted as (a), is the operation of changing vertices' colors, and a permutation followed by an (a) is a permutation asymmetrization. The color symmetry groups I contains only permutations, whereas color symmetry groups II comprise permutation asymmetrizations as well as permutations. Four DNA knots and links in nature are analyzed and tabulated consisely. In addition, the well-known figure-of-eight knot and Borromean rings are discussed in much the same way.

DNA↗

Finite element analysis on preferable I-bar clasp shape.

An I-bar clasp is one of the most popular direct retainers for distal-extension removable partial dentures. However, no adequate information is available on preferable shape as determined by biomechanics. This study aimed (1) to investigate, by finite element analysis (FEA), the dimensions and stress of I-bar clasps having the same stiffness, and (2) to estimate a mechanically preferable clasp design. Three-dimensional FEA models of I-bar clasps were created with vertical and horizontal straight sections connected by a curved section characterized by six parameters: thickness of the clasp tip, width of the clasp tip, radius of the curvature, horizontal distance between the base and the vertical axis, vertical dimension between the tip and the horizontal axis, and taper (change of width per unit length along the axis). Stress was calculated with a concentrated load of 5 N applied 2 mm from the tip of the clasp in the buccal direction. A thinner and wider clasp having an taper of 0.020-0.023 and radius of curvature of 2.75-3.00 showed less stress. The results suggest that such a shape might be the preferable I-bar clasp shape as biomechanical viewpoint.

Algorithms↗

Metamorphosis of 3D polyhedral models using progressive connectivity transformations.

Three-dimensional metamorphosis is a powerful technique to produce a 3D shape transformation between two or more existing models. In this paper, we propose a novel 3D morphing technique that avoids creating a merged embedding that contains the faces, edges, and vertices of two given embeddings. This novel 3D morphing technique dynamically adds or removes vertices to gradually transform the connectivity of 3D polyhedrons from a source model into a target model and simultaneously creates the intermediate shapes. In addition, a priority control function provides the animators with control of arising or dissolving of input models' features in a morphing sequence. This is a useful tool to control a morphing sequence more easily and flexibly. Several examples of aesthetically pleasing morphs are demonstrated using the proposed method.

Algorithms↗

Analysis of stiffness and stress in I-bar clasps.

An I-bar clasp is one of the most popular direct retainers for distal-extension removable partial dentures. However, no adequate information is available on the shape associated with biomechanics. This study aimed (1) to establish a three-dimensional (3D) finite-element modelling method of I-bar clasps, and (2) to clarify the effect of the shape on the stress and stiffness of I-bar clasps. 3D computer models of I-bar clasps were created with vertical and horizontal straight sections connected with a curved section with six parameters: thickness of the clasp tip (T), width of the clasp tip (W), radius of the curvature (R), horizontal distance between the base and the vertical axis (H), vertical dimension between the tip and the horizontal axis (V), taper (change of width per unit length along the axis)(Tp). Stress decreased as T, W, R and Tp increased, and as V decreased. Stiffness (which is proportional to retention) increased as T, W, R and Tp increased, and as H and V decreased. In both stress and stiffness, the effects of T and Tp were especially large. From the results, a systematic formula between the clasp shape and the stiffness was derived.

Computer Simulation↗

A comparison of flap vascular anatomy in three rhytidectomy techniques.

The purpose of this study was to examine differences in blood supply to facial flaps created by three rhyditectomy techniques. The techniques chosen for comparison included a two-layer technique, consisting of separate subcutaneous and extended submuscular aponeurotic system (SMAS) dissections, the Composite dissections as described by Hamra, and a subperiosteal dissection. Six cadavers were injected with lead oxide before dissection, and eight were injected after dissection. After allowing the lead oxide to set, the soft tissues were removed from the face. Vascular patterns of the face were interpreted from x-rays taken of the specimens. Results of the injections performed before dissection confirmed contributions of previously described arteries, including the transverse facial, facial, infra-orbital and terminal branches of the ophthalmic. In addition, there are numerous branches that connect these vessels to each other. The most consistent of these include the masseteric, jugal, submental, labial, angular and nasal arteries. The patterns of communications between these vessels allow for the visualization of three vertically oriented vascular zones, each connected to the next by choke zones where anastomoses occur. Dissections performed before injection reveal increased filling of the vessels through more of the flap on the Composite side when compared with the two-layered dissection, absence of vessels in the SMAS, and filling across all three zones on the subperiosteal side. We conclude that there are vascular regions in the face connected by anastomotic choke zones. Separate subcutaneous and sub-SMAS dissections interrupt the vascular connection between zones. Arterial continuity is better-maintained in the Composite lift and is literally undisturbed in the subperiosteal lift.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Vessels↗