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At least 109 records · Page 6Linked to original sources
PubMed1982

Rate dependent left bundle branch block with gradual transition between normal intraventricular conduction and complete left bundle branch block. A case report.

A case of 70-year-old woman with ischemic heart disease is presented. The electrocardiogram showed atrial fibrillation and a tachycardia-dependent, left bundle branch block. A number of intermediate QRS patterns from normal intraventricular conduction to complete left bundle branch block were seen, and the transition was gradual. Increasing grades of aberrance were seen following a shorter preceding cycle length.

Aged↗
PubMed1976

Brain stem self-stimulation attenuated by lesions of medial forebrain bundle but not by lesions of locus coeruleus or the caudal ventral norepinephrine bundle.

Midbrain tegmental intracranial self-stimulation (ICSS) was not attenuated by ipsilateral or bilateral locus coeruleus lesions. Certain of these lesions were followed by histochemical confirmation that the majority of locus coeruleus neurons was destroyed, and biochemical evidence that over 80% of the cortical norepinephrine was depleted. To test the possibility that the surviving ICSS was due to stimulation of another norepinephrine system, histochemically verified ipsilateral or bilateral lesions of the ventral norepinephrine bundle were administered to a second group of midbrain tegmental ICSS animals. These lesions resulted in marked loss of body weight, but had no effect on ICSS. In a third experiment, lesions were made in the medial forebrain bundle (MFB) ipsilateral to midbrain tegmental ICSS electrodes. These lesions resulted in attenuation of ICSS which was directly proportional to the extent of MFB damage. On the basis of these data alone, however, it was not possible to identify the ciritical fibers supporting ICSS. It was oncluded that the locus coeruleus does not play a necessary role in midbrain tegmental ICSS.

Animals↗
PubMed1989

A new 400-kD protein from isolated adherens junctions: its localization at the undercoat of adherens junctions and at microfilament bundles such as stress fibers and circumferential bundles.

In the previous study, we succeeded in isolating the cell-to-cell adherens junctions from rat liver (Tsukita, S., and S. Tsukita. 1989. J. Cell Biol. 108:31-41.). In this study, we have obtained mAbs specific to the 400-kD protein, which was identified as one of the major constituents of the undercoat of isolated adherens junctions. Immune blot analyses showed that this protein occurs in various types of tissues. Immunofluorescence microscopy and immune electron microscopy have revealed that this protein is distributed not only at the undercoat of adherens junctions but also along actin bundles associated with the junction in nonmuscle cells: stress fibers in cultured fibroblasts and circumferential bundles in epithelial cells. The partially purified protein molecule looks like a slender rod approximately 400 nm in length. By virtue of its molecular shape, we have named this protein 'tenuin' (from Latin 'tenuis', thin or slender).

Actin Cytoskeleton↗
PubMed2001

Ultrastructural localization of photosynthetic and photorespiratory enzymes in epidermal, mesophyll, bundle sheath, and vascular bundle cells of the C4 dicot Amaranthus viridis.

In the leaves of the NAD-malic enzyme (NAD-ME)-type C4 dicot Amaranthus viridis L., there are chloroplasts in the vascular parenchyma cells (VPC), companion cells (CC), ordinary epidermal cells (EC), and guard cells (GC), as well as in the mesophyll cells (MC) and the bundle sheath cells (BSC). However, the chloroplasts of the VPC, CC, EC, and GC are smaller than those of the MC and BSC. In this study, the accumulation of photosynthetic and photorespiratory enzymes in these leaf cell types was investigated by immunogold labelling and electron microscopy. Strong labelling for phosphoenolpyruvate carboxylase was found in the MC cytosol. Weak labelling was observed in the CC and GC cytosol. Labelling for pyruvate, Pi dikinase occurred to varying degrees in the chloroplasts of all cell types except CC. Labelling for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase was detected in the chloroplasts of all cell types except MC. For both NAD-ME and the P-protein of glycine decarboxylase, intense labelling was found in the BSC mitochondria; weaker labelling was recognized in the VPC mitochondria. These data indicate that when not only the MC and BSC but also the other leaf cell types are included, the cell-specific expression of the enzymes in C4 leaves becomes more complex than has been known previously. These findings are discussed in relation to the metabolic function of epidermal and vascular bundle cells.

Blotting, Western↗
PubMed2003

Adsorption of argon on carbon nanotube bundles and its influence on the bundle lattice parameter.

We report experimental studies of the adsorption characteristics and structure of both 36Ar and 40Ar on single-wall carbon nanotube bundles. The structural studies make use of the large difference in coherent neutron scattering cross section for the two Ar isotopes to explore the influence of the adsorbate on the nanotube lattice parameter. We observe no dilation of the nanotube lattice with 40Ar, and explain the apparent expansion of this lattice upon 36Ar adsorption by the location of the adsorbed Ar atoms on the outer bundle surface.

Journal Article↗
PubMed1989

Inorganic Carbon Diffusion between C(4) Mesophyll and Bundle Sheath Cells: Direct Bundle Sheath CO(2) Assimilation in Intact Leaves in the Presence of an Inhibitor of the C(4) Pathway.

Photosynthesis rates of detached Panicum miliaceum leaves were measured, by either CO(2) assimilation or oxygen evolution, over a wide range of CO(2) concentrations before and after supplying the phosphoenolpyruvate (PEP) carboxylase inhibitor, 3,3-dichloro-2-(dihydroxyphosphinoyl-methyl)-propenoate (DCDP). At a concentration of CO(2) near ambient, net photosynthesis was completely inhibited by DCDP, but could be largely restored by elevating the CO(2) concentration to about 0.8% (v/v) and above. Inhibition of isolated PEP carboxylase by DCDP was not competitive with respect to HCO(3) (-), indicating that the recovery was not due to reversal of enzyme inhibition. The kinetics of (14)C-incorporation from (14)CO(2) into early labeled products indicated that photosynthesis in DCDP-treated P. miliaceum leaves at 1% (v/v) CO(2) occurs predominantly by direct CO(2) fixation by ribulose 1,5-bisphosphate carboxylase. From the photosynthesis rates of DCDP-treated leaves at elevated CO(2) concentrations, permeability coefficients for CO(2) flux into bundle sheath cells were determined for a range of C(4) species. These values (6-21 micromoles per minute per milligram chlorophyll per millimolar, or 0.0016-0.0056 centimeter per second) were found to be about 100-fold lower than published values for mesophyll cells of C(3) plants. These results support the concept that a CO(2) permeability barrier exists to allow the development of high CO(2) concentrations in bundle sheath cells during C(4) photosynthesis.

Journal Article↗
PubMed2004

Supracallosal longitudinal fiber bundle: heterotopic cingulum, dorsal fornix or Probst bundle?

A thick longitudinal fiber bundle found within the dorsal corpus callosum in two unrelated adults (in a micrencephalic female patient and incidentally in another male patient) is considered to be a congenital aberrant cingulum. Agenesis or apparent hypoplasia of the indusium griseum of the limbic-cingular system as an accompanying finding in the present cases may support this hypothesis. The dorsal fornix and Probst bundle are discussed in terms of differential diagnosis, although there was no further support for this possibility. The hyperplastic dorsocallosal gray substance is excluded.

Adult↗
PubMed1988

Colchicine causes intrasomatic neurofilament bundles in the mesencephalic trigeminal nucleus and intradendritic bundles in other brain regions.

The effect of a single intracerebroventricular injection of colchicine on the distribution of organelles in neurons of the mesencephalic nucleus of the trigeminal nerve, the inferior colliculus and the deep cerebellar nuclei was studied. In the mesencephalic nucleus of the trigeminal nerve colchicine produced a dramatic accumulation of neurofilament bundles in the soma of these neurons and did not produce a reduction in the number of lysosomes. In other neuronal populations studied, colchicine produced neurofilament bundles in the dendrites and a reduction of lysosomes from the soma of neurons.

Animals↗
PubMed1996

[Transcatheter radiofrequency bundle branch ablation in bundle branch reentry ventricular tachycardia: report of a case].

Two patients with branch to branch ventricular tachycardia (BBVT) are reported: successful radiofrequency catheter ablation of BBVT was performed in both, delivering energy distally to the point where the maximum amplitude of His deflection occurred, so that a wide ventricular deflection was obtained without any atrial electrogram. No significant conduction delay appeared but a right bundle branch block. HV intervals during BBVT resulted equal or longer than in sinus rhythm: whether this was secondary to anatomical or functional variations or to the possibility that the His bundle may be "bystander" in BBVT, is discussed.

Adult↗
PubMed2005

Discontinuous conduction in mouse bundle branches is caused by bundle-branch architecture.

BACKGROUND: Recordings of the electrical activity of mouse bundle branches (BBs) suggest reduced conduction velocity (CV) in the midseptal compared with the proximal part of the BB. The present study was performed to elucidate the mechanism responsible for this slowing of conduction. METHODS AND RESULTS: Hearts of 16 mice were isolated and Langendorff perfused. After the right and left ventricular free walls were removed, the extracellular activity of the BB was mapped with a 247-point electrode. Premature stimulation was used to estimate CV restitution in the BBs. Expression/distribution of connexin40 (Cx40), Cx43, and Cx45 was determined. Morphology of the conduction system was assessed by whole-mount acetylcholine esterase staining and in Cx40(+/KI-GFP) hearts. Effective CV in the midseptal part of the left and right BBs was reduced by 50% compared with the proximal BB. CV restitution in the proximal and midseptal parts of the BBs was similar. Myocytes labeled positive for Cx40 and Cx45 in the entire BB. Cx43 colocalized with Cx40 and Cx45 only in the very distal BB. Subcellular distribution of gap junctions differed between proximal and distal BBs. Geometry of the midseptal and distal BBs revealed on both sides a profuse network of interlacing fibers, whereas the proximal BB consisted of a single (right BB) or multiple (left BB) parallel fibers. CONCLUSIONS: Comparison of connexin expression/distribution, geometry of the BBs, and CV characteristics suggests that increased path length for activation resulting from BB geometry is responsible for the apparently reduced CV in the midseptal BB of the mouse heart.

Animals↗
PubMed1990

Medial forebrain bundle of the rat: IV. Cytoarchitecture of the caudal (lateral hypothalamic) part of the medial forebrain bundle bed nucleus.

In the preceding study (Geeraedts et al.: J. Comp. Neurol. 294:507-536, '90), the rostral or telencephalic portion of the rat's bed nucleus of the medial forebrain bundle (MFB) has been parcellated into several cytoarchitectonically distinct cellular groups and subgroups. The purpose of the present investigation is to subject the caudal or lateral hypothalamic (LH) portion of the MFB bed nucleus to a detailed cytoarchitectonic analysis. This analysis is based on the same materials, methods, and cytoarchitectonic criteria that were also employed in the preceding study. In contrast to descriptions in the literature, it was found that the LH-region constitutes a very heterogeneous population of neurons with an evident arrangement into groups, several of which have not been identified previously. Many of these cellular groups are partly or entirely located within the boundary of the LH-trajectory of the MFB as previously established by Nieuwenhuys et al. (J. Comp. Neurol. 206:49-81, '82). These groups are designated here as the MFB-related cellular groups. They appear to be arranged into two longitudinal zones. Both zones are caudally replaced by the ventral tegmental area (VTA) and a part of the mesencephalic tegmentum (TEGM1). The lateral zone lies in close proximity to the internal capsule/cerebral peduncle and comprises the following cellular groups: the ventrolateral subarea of the lateral hypothalamic area (LHVL), the anterolateral subarea of the lateral hypothalamic area (LHAL), the lateral tuberal nucleus (TUL), the pre-subthalamic nucleus (PSUT), the retro-subthalamic nucleus (RSUT), the anterodorsal subarea of the lateral hypothalamic area (LHAD), and the lateral hypothalamic nucleus (LHN). The medial zone consists of the following cellular groups: the intermediate hypothalamic area (IHA), the medial tuberal nucleus (TUM), the perifornical nucleus (PFX), the lateral supramammillary nucleus (SUL), the submammillothalamic nucleus (SMT), and the nucleus geminus posterior (GEP). The cellular groups of the medial zone together with the tuberomammillary nucleus groups of the medial zone together with the tuberomammillary nucleus (TUMM) are positioned at the interface between the lateral and the medial hypothalamus, and form an array of cellular groups indicated in our study as the intermediate division of the hypothalamus. The MFB-related cellular groups are dorsally, medially, ventrally, and laterally surrounded by rather well-known brain structures. Both the MFB-related cellular groups and the surrounding structures have been identified and delimited. This resulted in a new, elaborate cytoarchitectonic atlas of the rat's lateral hypothalamic region.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Light and electron microscopic studies on the medial forebrain bundle in rat: III. Degenerated nerve elements in the medial hypothalamic nuclei following surgical transections of the medial forebrain bundle.

Transections of the rat medial forebrain bundle at various levels and the separation of the medial and lateral hypothalamus were performed to study with light and electron microscopy axonal and terminal degeneration in the arcuate, ventromedial and dorsomedial nuclei and in the median eminence. Fibres entering the MFB from various directions participate in the innervation of the arcuate nucleus. The bulk of extrahypothalamic fibres terminating in the median eminence derive from the lower brain stem and reach their target through the MFB. Preoptic originating and transient fibres also terminate in the median eminence. Following parasagittal separation of the medial and lateral hypothalamus massive degeneration was found in both layers of the median eminence. This is likely to be due to interruption of the supraoptic-hypophyseal tract but axons of intrinsic MFB-neurons might also contribute to the innervation of the median eminence.

Animals↗
PubMed2006

Comparison of presence and extent of coronary narrowing in patients with left bundle branch block without diabetes mellitus to patients with and without left bundle branch block but with diabetes mellitus.

We prospectively analyzed the clinical, echocardiographic, and coronary arteriographic data of 51 patients with type 2 diabetes mellitus with left bundle branch block (LBBB), 51 patients with type 2 diabetes mellitus without LBBB, and 51 patients with isolated LBBB matched for age and gender. Extent of coronary artery disease (CAD) was classified according to the standard method into 1-, 2-, or 3-vessel disease and was estimated by calculation of the Gensini score. The left ventricular ejection fraction was analyzed by echocardiography. Age, gender, and percentage of patients with a smoking habit or family history of CAD did not differ among the groups. The rates of hypertension and levels of serum creatinine, cholesterol, and triglycerides were statistically higher in group I compared with the other 2 groups. Patients with diabetes and LBBB (group I) had significantly higher scores for the severity (Gensini score) of CAD (p <0.001) and more 3-vessel disease (p <0.001). After adjustment for hypertension, hypertriglyceridemia, and hypercholesterolemia with covariance analysis, the presence of LBBB was also associated with a higher Gensini score in patients with diabetes compared with those with diabetes but without LBBB and those with isolated LBBB (p <0.001). The present study, for the first time, has shown that patients with type 2 diabetes mellitus and concomitant LBBB have more severe and extensive CAD and advanced left ventricular dysfunction compared with those with diabetes but without LBBB and those with isolated LBBB.

Aged↗
PubMed1976

Intractable paroxysmal tachycardia caused by a concealed retrogradely conducting Kent bundle. Demonstration by epicardial mapping and cure of tachycardias by surgical interruption of the His bundle.

Electrophysiological and epicardial mapping studies are described in a patient without pre-excitation who had intractable recurrent paroxysmal supraventricular tachycardia. Electrophysiological studies revealed fixed VA conduction times during both rapid ventricular pacing and coupled ventricular stimulation. Catheter mapping of atrial activation during retrograde conduction and during induced paroxysmal supraventricular tachycardia revealed early distal coronary sinus activation (posterior left atrium) relative to the low septal, low lateral, and high lateral right atrium. These studies suggested the presence of a concealed left-sided bypass tract. The patient underwent surgical interruption of the His bundle for control of paroxysmal supraventricular tachycardia. Epicardial mapping of the atria (during ventricular pacing) confirmed the presence of a concealed left-sided bypass tract. Surgery produced antegrade av block (while retrograde conduction was maintained) and total cure of paroxysmal supraventricular tachycardia. This is the first reported case of a concealed retrograde extranodal pathway documented by epicardial mapping.

Adult↗
PubMed1980

Comparison of Frank-vectorcardiograms of normal conduction and right bundle branch block in patients with intermittent or transient right bundle branch block.

For the purpose of obtaining fundamental data to make the diagnostic criteria for coexisting electrocardiographic abnormalities in right bundle branch block (RBBB), the Frank-vectorcardiographic and electrocardiographic parameters were studied in both normal and RBBB conductions in 25 patients (16 males and 9 females, aged 6 to 78 years) with intermittent or transient RBBB. There were no statistically significant differences in the corresponding instantaneous QRS vectors between normal and RBBB conductions during the first 10.4 (+/- 3.2) msec of the QRS duration on the average. No statistically significant differences existed in the mean Q amplitudes of the Frank leads between normal and RBBB conductions. After the development of RBBB, voltages of Rx and Ry, and the planar maximum QRS vectors decreased approximately by 10% on the average, and Rz decreased significantly by 63.9% on the average, and S amplitudes of the 3 Frank leads increased significantly. We observed 3 patients showing a complete reversal of the sense of inscription of the horizontal QRS loop from counterclockwise to clockwise after the development of RBBB. Two of these patients showed no clinical evidence of cardiac or pulmonary diseases except for RBBB. After the appearance of RBBB, maximum T vectors deviated significantly posteriorly in the horizontal and left sagittal planes. Twenty-three patients showed counterclockwise inscription of the T loop both in the horizontal and left sagittal planes, and 9 patients in the frontal plane. After the development of RBBB, we observed a complete reversal in the sense of inscription of the T loop from counterclockwise to clockwise in 13 cases (56.5%) in the horizontal plane, in 15 cases (65.2%) in the left sagittal plane, and in 8 cases (88.9%) in the frontal plane.

Adolescent↗
PubMed1996

Loading of the two bundles of the posterior cruciate ligament: an analysis of bundle function in a-P drawer.

The purpose of this study was to clarify the role of the posterior cruciate ligament (PCL) in posterior drawer and to test the hypothesis that the anterolateral (aPC) and the posteromedial (pPC) bundles have different functions over the range of flexion. Selective cutting was utilised to determine percentage contributions to resisting posterior drawer. At lower flexion angles the primary restraint to posterior drawer was not the PCL but combined secondary structures. The percentage contribution of the combined secondary structures dropped below 50% at 30, 20 and 15 degrees of flexion for 2, 4 and 6 mm displacement respectively. In the midrange of flexion (40-120 degrees) the aPC was the primary restraint as it resisted between 50 and 75% of posterior drawer force. Towards full flexion the contribution of the aPC reduced, while the contribution of the pPC approximately doubled from extension to full flexion. This resulted in equal contributions from the aPC and pPC at full flexion for 2 and 4 mm displacement. For 6 mm displacement the percentage contribution of the pPC rose from 23% at extension to 57% of the total restraint at 130 degrees of flexion when it exceeded the 36% contribution of the aPC, although not significantly (p = 0.053).

Aged↗