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At least 811 records · Page 45Linked to original sources
PubMed1996

Long-term animal survival with an implantable axial flow pump as a left ventricular assist device.

We are developing an axial flow blood pump with Nimbus Inc. (AxiPump). For in vivo evaluation the AxiPump has been used as a left ventricular assist device with a left ventricular and descending aorta cannulation and implantation in a small pocket on the left lateral abdominal wall just posterior to the costal margin. Electrical and flow probe leads exit the body transcutaneously. A purge line that delivers the purge fluid for lubrication of the seal between the rotor and stator bodies in the purge fluid bearing system is tunneled with the other leads. Following acute animal studies, 3 animals have been supported for over 1 month with this AxiPump system. All laboratory results were within normal limits except during a recovery period from surgical damage. Hemolysis was not a serious problem. In the first case, the purge system failed at 28 days, and in the second and third cases, the nonpurge bearing system worked well for 57 and 52 days, respectively. Bearings are still under development in this kind of pump. However, this success encourages us to improve the AxiPump as a long-term assist device.

Animals↗
PubMed1978

Postnatal development and differentiation of the opossum submandibular gland.

The postnatal development and differentiation of the submandibular salivary gland has been examined in sixteen groups of young opossums. At birth the glandular elements, dispersed in loose connective tissue, consist only of ducts that are immature in appearance and of irregular secretory end-pieces. Development occurs in two phases, the first from birth to approximately 31 days postnatum, and the second thereafter. During the first phase the ductular elements show separation into intercalated and intralobular ducts, and attain structural maturity. The larger ducts are concentrated centrally within each lobule and lie in a markedly vascular connective tissue. The secretory end-pieces, initially acinar in form, are lined by proacinar cells which exhibit intercellular canaliculi at the lateral cell membranes and a few dense granules in the apical cytoplasm. During the second phase of development extensive changes occur within the secretory end-pieces, which elongate to form a system of branching tubules. Component cells show an increased granular content, and those in the main body of the tubules differentiate into mucous cells. By 34 cm postnatum the proacinar cells in the bulbous endings of the tubules are replaced by special serous cells possessing intercellular canaliculi and secretory granules which are either electron-lucent or electron-dense. The sequence of changes that occur during postnatal development is discussed and related to possible functional activities. The early development of the ducts may be correlated with their role in homeostasis, while the later development of secretory tubules and the differentiation of secretory cell types may be related to the onset of weaning, and may possibly be induced by this major change in dietary habit.

Age Factors↗
PubMed1993

Carbohydrate-carbohydrate interactions of a novel acidic glycan can mediate sponge cell adhesion.

Cell recognition and adhesion were first demonstrated in marine sponges. These phenomena were later shown in Microciona prolifera sponge to be mediated by a Ca(2+)-dependent self-association of adhesion proteoglycans (APs) attached in a species-specific manner to cell-surface receptors. Using the same experimental system we now provide three lines of evidence that highly polyvalent Ca(2+)-dependent carbohydrate-carbohydrate interactions of a novel AP glycan represent the basis of AP-AP self-binding and thus of cell adhesion. 1) A specific monoclonal antibody which blocks cell aggregation and AP bead adhesion identified a highly repetitive novel carbohydrate epitope (2500 sites) in an acidic glycan of M(r) = 200 x 10(3) (g200) from AP. 2) Reconstitution of the Ca(2+)-dependent self-interaction activity of AP was achieved by cross-linking the purified protein-free g200 glycan into polymers of similar valency as the native AP. 3) Beads coated with the protein-free g200 glycan showed a Ca(2+)-dependent aggregation equivalent to that of AP beads. Carbohydrate and amino acid analyses of the g200 glycan purified by gel electrophoresis, high performance liquid chromatography gel filtration, and ion exchange chromatography yielded six components in the following proportions; 68 fucose, 32 glucuronic acid, 2 mannose, 18 galactose, 19 N-acetylglucosamine, and 1 asparagine residue. These unique chemical features together with immunological and enzymological analyses suggest that the g200 glycan is a large highly fucosylated, acidic, N-linked polysaccharide with a novel structure distinct from that of other known glycosaminoglycans.

Animals↗
PubMed1999

Distribution of calcium/calmodulin-dependent kinase 2 in the brain of Apteronotus leptorhynchus.

Antibodies directed against the mammalian alpha and beta subunits of calcium/calmodulin-dependent kinase 2 (CaMK2) and brain dissection were used for immunoblot analysis of these proteins in various brain regions of Apteronotus leptorhynchus. Western blots revealed that the CaMK2alpha antibody labeled a single band of the expected molecular mass (approximately 50 kDa) for this enzyme in rat cortex and electric fish brain. CaMK2alpha was enriched in fish forebrain and hypothalamus and also strongly expressed in midbrain sensory areas. Western blots revealed that CaMK2beta antibodies labeled bands in an appropriate molecular mass range (approximately 58-64 kDa) for this enzyme in mammalian cortex and electric fish brain. However, a higher molecular mass band (approximately 80 kDa) was also labeled; because all these bands were eliminated by preadsorbtion with the CaMK2-derived peptide antigen, they may all represent CaMK2beta-like isoforms. We mapped the brain distribution of CaMK2 isoforms with emphasis on the electrosensory system. CaMK2alpha was present at high density in dorsal forebrain, hypothalamic nuclei, torus semicircularis, and tectum. It was also enriched in discrete fiber tracts in forebrain, diencephalon, and rhombencephalon. CaMK2beta-like isoforms were enriched in ventral forebrain, hypothalamic nuclei, torus semicircularis and the reticular formation. Unlike CaMK2alpha, CaMK2beta -like isoforms were predominantly present in cell bodies and rarely found in fiber tracts or neuropil. In the electrosensory lateral line lobe, CaMK2alpha was restricted to specific feedback fibers, i.e., tractus stratum fibrosum and its terminal field in the ventral molecular layer. In contrast, CaMK2beta-like isoforms were enriched in somata and dendrites of pyramidal cells and granular interneurons.

Animals↗
PubMed2003

Parenchymal anaplastic ependymoma with intratumoral hemorrhage: a case report.

We report an unusual case of a 56-year-old woman with a supratentorial anaplastic ependymoma localized in the parenchyma without continuity with the ventricular system and brain surface. The patient presented with vertigo, and a calcified mass was detected in the left temporal parenchyma. Five years later, she had seizure of the right extremities. Computed tomographic scanning and magnetic resonance imaging revealed an enhanced mass with an intratumoral hemorrhage adjacent to the calcified mass. Subtotal removal of the tumor was performed. The histological analysis revealed that the tumor was an anaplastic ependymoma. After focal radiation therapy (50 Gy), the outcome was favorable, although the residual lesion was still seen on the images. Ependymomas usually arise from the cells lining the ventricular system and the central canal of the spinal cord. We discuss the summary of published cases of supratentorial ectopic ependymoma since the first case in 1995.

Cerebral Ventricles↗
PubMed1981

Acetylcholinesterase in the platelet-megakaryocyte system. II. Structural localization in megakaryocytes of the rat, mouse, and cat.

Acetylcholinesterase (AchE) activity (EC 3.7.1.7) was demonstrated cytochemically in the megakaryocyte (MK) line of differentiation in the red bone marrow of rat, mouse, and cat. Activity was detected in the Golgi complexes of cells considered to be committed MK precursor cells, and was found in Golgi cisterns through all subsequent stages of MK maturation. In the early, basophilic stage of differentiation some MK showed AchE activity in the perinuclear cistern and in a few profiles of the granular endoplasmic reticulum, but reaction was absent from this location at later maturation stages. Concomitantly with the development of the demarcation membrane system, another membrane system appeared; this system consisted of smooth-surfaced, tortuous tubules and narrow cisterns, and it displayed AchE activity through cytoplasmic maturation. In thrombocytogenic MK, the smooth AchE-reacting membranes (SAM) became the AchE-reacting dense tubular system (DTS) of released MK cytoplasm. The MK of the species studied also contained a varying number of AchE-reacting granules (mouse greater than cat greater than rat) which were distinct from alpha-granules.

Acetylcholinesterase↗
PubMed2005

Distinct roles of EGF repeats for the Notch signaling system.

Notch is a single-pass transmembrane receptor that mediates cell fate choice in various species and developmental contexts. The Notch signal is transduced by its intracellular domain, which acts as a transcriptional activator, and is released from the plasma membrane by proteolytic cleavages. This process is initiated by intercellular association of the epidermal growth factor (EGF) repeats between Notch and the DSL (Delta, Serrate, Lag-2) ligands but the detailed mechanism is yet to be clarified. Here we demonstrate that Notch1 can form homodimers, which is achieved by its EGF motifs. The Notch1 dimer formation increased in response to ligand presentation and HES1 promoter was stimulated, implying that receptor homodimerization is an important initial step in Notch signal transduction. EGF motifs also serve as a protection against proteases, including TNF-alpha converting enzyme, which prevents Notch1 from ligand-independent activation. Multiple functions of the Notch EGF motifs, such as the prevention of constitutive activation, reciprocal interaction with the ligands and lateral interaction for homodimerization, appear to constitute crucial elements of the Notch signaling system.

Amino Acid Motifs↗
PubMed2004

Fluorescent and dispersion experiments on biological membranes under micro-gravity.

Almost all biological processes, especially those involved in signal reception and signal transduction, depend on the physical and physiological properties of biological membranes. It has been shown, that neuronal tissue and the speed of the action potential (AP) which is the basic neuronal unit of all nervous activity, is sensitive to changes in gravity as well as to other weak external forces. We strongly suppose the membrane to be the most important factor in gravitational responses although it is very difficult to observe the effects of gravity changes on these fragile thermodynamic systems. Therefore we developed two different experiments to measure the structural changes and the lateral membrane tension of spheroid cells under microgravity.

Animals↗
PubMed1991

Magnetic stimulation of corticonuclear systems and of cranial nerves in man: physiological basis and clinical application.

After transcranial magnetic brain stimulation, two types of responses in muscles supplied by cranial nerves (trigeminal, facial, accessory, and hypoglosseal nerves) can be observed. With a placement of the coil center approximately 6 cm lateral of the vertex on the interaural line, purely ipsilateral responses can be evoked in the cranial muscles which are induced by excitation of the nerves at or near their intracisternal course ('short-latency' responses). With the coil center 4 cm lateral of the vertex bilaterally 'long-latency' responses can be evoked which are the result of an excitation of that part of the motor cortex which mediates impulses to the motoneurons of cranial nerves via the corticonuclear tract. Evaluations of latencies and amplitudes of the responses in cranial muscles, and of the excitability of their supplying nerves at a proximal site considerably improve the electrophysiological assessment of the site, severity, and prognosis of cranial motor disturbances, especially in facial nerve palsies.

Cranial Nerves↗
PubMed1987

Detection of c-rel-related transcripts in mouse hematopoietic tissues, fractionated lymphocyte populations, and cell lines.

A portion of the human cellular homolog of v-rel, the transforming gene of the leukemogenic retrovirus reticuloendotheliosis virus, strain T, was used to survey RNAs from several mouse tissues, selected lymphocyte populations, and hematopoietic cell lines for c-rel expression. Relatively high levels of a high-molecular-weight transcript were observed in peripheral B and T cells, whereas lower levels were detectable in functionally immature thymocytes. These results suggested that, unlike c-myb and c-ets, the c-rel proto-oncogene plays a role in later stages of lymphocyte differentiation.

Animals↗
PubMed1998

Factors influencing human sperm kinematic measurements by the Celltrak computer-assisted sperm analysis system.

This study examines the effect of varying several factors, both extrinsic and technology-dependent, on the reconstruction of human sperm trajectories and the derived kinematic measurements using videotapes and the Motion Analysis Celltrak/S instrument. In semen samples from normal healthy men, curvilinear (VCL) and straight line velocities (VSL) were found to increase 1.5-fold, and linearity (LIN) of trajectories and amplitude of lateral head displacement (ALH) increased 1.25-fold when the temperature of analysis was raised from 24 to 37 degrees C. Only VCL and VSL were found to increase significantly between 24 and 37 degrees C for sperm samples selected by Percoll gradient and incubated in a capacitating medium. An analysis chamber of 20 microm depth was found to be adequate for seminal sperm samples while for Percoll-selected sperm samples the analysis in a 50 microm depth provided the highest proportions of spermatozoa with the highest VCL and the largest ALH. The grey level detection threshold required careful adjustment: using a threshold lower than the optimal threshold produced spurious sperm trajectories for seminal sperm samples and rejected some trajectories for Percoll-selected sperm samples. Definition of the appropriate frame rate and maximum burst speed was critical for valid trajectory reconstruction and therefore adequate derived kinematic measurements. Optimal values of these parameters were found to be 30 Hz and 400 microm/s for seminal spermatozoa and 60 Hz and 700 microm/s for selected spermatozoa. The optimal values of 'ALH path-smoothing factor' used to calculate average path and ALH were 5-10 points for seminal spermatozoa analysed at 30 Hz and 15-20 points for selected spermatozoa analysed at 60 Hz. We propose a set of standard conditions for reliable kinematic analysis of human spermatozoa using the Celltrak/S system.

Centrifugation, Density Gradient↗
PubMed1991

Positional cues governing cell migration in leech neurogenesis.

The stereotyped distribution of identified neurons and glial cells in the leech nervous system is the product of stereotyped cell migrations and rearrangements during embryogenesis. To examine the dependence of long-distance cell migrations on positional cues provided by other tissues, embryos of Theromyzon rude were examined for the effects of selective ablation of various embryonic cell lines on the migration and final distribution of neural and glial precursor cells descended from the bilaterally paired ectodermal cell lines designated q bandlets. The results suggest that neither the commitment of q-bandlet cells to migrate nor the general lateral-to-medial direction of their migration depend on interactions with any other cell line. However, the ability of the migrating cells to follow their normal pathways and to find their normal destinations does depend on interactions with cells of the mesodermal cell line, which appears to provide positional cues that specify the migration pathways.

Animals↗
PubMed1991

Contrast and stereoscopic visual stimuli yield lateralized scalp potential fields associated with different neural generators.

The use of dynamic random-dot stereograms (RDS) allows to investigate evoked potential components generated exclusively by cortical structures. We analyzed the scalp distribution of stereoscopically evoked or contrast evoked potential field by recording electrical brain activity in 20 channels simultaneously from an electrode array covering the occipital scalp areas. Evoked brain activity was obtained from 13 healthy adults with dynamic RDS stimuli presented as a stereoscopic checkerboard pattern in the center, or in the right or left visual half-field. Such stereoscopically evoked scalp potential distributions were compared to those elicited by a conventional 2-dimensional checkerboard reversal stimulus of the same mean luminance and retinal extent. We found that the latencies of the major evoked components were similar for contrast and stereoscopic stimuli, while significant differences were observed when we compared the strength of the evoked potential fields or the topographical pattern elicited by lateralized stereoscopic and contrast stimuli. The functional relation of evoked electrical brain activity to the retinal stimulus location was significantly different for stereoscopic and contrast stimuli. We present evidence that stereoscopic perception relies on the activation of cortical structures in the human visual system that are different from those activated by comparable contrast stimuli, supporting the conclusions derived from our earlier electrophysiological experiments on stereoscopic vision. These data on the physiological correlates of processing of stereoscopic information in humans are in line with the results obtained with single neuron recordings from the cat and monkey visual cortex.

Adolescent↗
PubMed2000

Perceiving binocular depth with reference to a common surface.

A common surface is a spatial regularity of our terrestrial environment. For instance, we walk on the common ground surface, lay a variety of objects on the table top, and display our favorite paintings on the wall. It has been proposed that the visual system utilizes this regularity as a reference frame for coding objects' distances. Presumably, by treating the common surface as such--i.e. an anticipated constant--the visual system can reduce its coding redundancy, and divert its resources to representing other information. For intermediate-distance space perception, it has been found that absolute distance judgment is most accurate when a common ground surface is available. Here we explored if the common surface also serves as the reference frame for the processing of binocular-disparity information, which is a predominant cue for near-distance space perception. We capitalized on an established observation where the perceived slant of a surface with linear binocular-disparity gradient is underestimated. Clearly, if the visual system utilizes this incorrectly represented slant surface as a reference frame for coding the objects' locations, the perceived depth separation between the objects will be adversely affected. Our results confirm this, by showing that the depth judgment of objects (two laterally separated vertical lines) on, or in the vicinity of, the surface is underestimated. Furthermore, we show that the impact of the common surface on perceived depth separation most likely occurs at the surface-representation level where the visual surface has been explicitly delineated, rather than at the earlier disparity-processing level.

Cues↗
PubMed1989

A low-cost system for computerized rodent weight logging with statistical analysis.

A system comprising a suite of 4 computer programs has been developed for on-line rodent weight data collection and statistical analysis using an IBM personal computer. Data can be collected from up to 3 separate trials simultaneously, and can be stored for later statistical analysis. Mettler balances were used for the animal weighing. A Mettler current loop adapter and a multiplexer were used to interface the balances with the computer.

Animals↗
PubMed1995

[Study on middle ear ventilation using positional tympanometry--post mastoidectomy ear].

The middle ear is a cavity surrounded by solid bone, lined with mucosa with a lumen filled with gas. To examine this unique ventilation system under atmospheric pressure, the middle ear pressure of 50 normal ears was previously examined. Positional tympanometry, whereby the middle ear pressure is increased as the subject assumes the lateral position under atmospheric pressure was used. As a result, (1) The middle ear pressure was elevated by the change from the sitting position to the lateral position. Venous pressure was regarded as causative factor of this pressure elevation. (2) The elevation of the middle ear pressure in the lateral position suggested gas production from the mastoid cells of the middle ear. In this study, a proportion of the mastoid cells were removed to resect a tumor of the internal acoustic meatus in conjunction with resection of an acoustic tumor. After resection the area was filled with fascia and fatty tissue. The middle ear pressure of each subject was monitored to determine the effect of a decrease in the mastoid cell volume on middle ear pressure. The results were continuously recorded every 12 seconds for the lower ear when the subjects were in the lateral position. The following results were obtained. (1) The elevation of the middle ear pressure due to positional change among subjects which had had acoustic tumors resected was noticeably greater than the elevation in normal ears. This is thought to have been the result of an elevation in cerebrospinal fluid pressure attributable to positional change, along with an elevation in intravenous pressure. (2) We made comparisons of increases in middle ear pressure 10 minutes after assuming the lateral position in 14 ears after acoustic tumor resection and in 21 normal ears. No noticeable differences were found in the middle ear pressure increases between the two groups despite the fact that the volume of the mastoid cells in the group that had tumors resected had been greatly reduced.

Acoustic Impedance Tests↗
PubMed1978

Influence of intraventricularly applied apomorphine on somato-vegetative reflexes in cats.

To obtain information about the dopaminergic neurotransmission processes taking part in the somatovegetative reflexes the effects of intraventricularly given apomorphine were studied in lightly anaesthetized cats. The level of blood pressure and the reflexogenic hypertension due to central sciatic nerve stimulation were not changed when apomorphine was applied into the lateral and third but was inhibited when given into the fourth ventricle. The nictitating membrane contractions elicited by sciatic nerve stimulation were inhibited by apomorphine when introduced into each part of the ventricular system. Thus the inhibitory dopaminergic synapses located in the structures lining the walls of the brain ventricular system reached by apomorphine appear to be involved in the central control of somato-vegetative reflexes.

Animals↗
PubMed1993

[Intraarticular fractures of the calcaneus: pathological description. Contribution of x-ray computed tomography].

Computed tomography (CT) is of cardinal importance in the study of displaced intra-articular fractures of the calcaneus, as with this imaging technique the primary fracture line of Palmer can be followed and its various locations visualised. If the three-stage classification system of these fractures as vertical, horizontal or mixed fractures, based on their radiological appearance, is adopted, a correlation can be established between the location of Palmer's line and these three anatomical types. The fundamental fracture line is medial in the vertical types, lateral in the horizontal types and is located in the centre of the posterior facet in the mixed types. It can be seen that the fundamental fracture line separates a laterally detached fragment which is always tilted, giving a vertical slope to the surface of the posterior facet which it supports and thus giving a vertical image. This fragment is itself separated from a medially detached fragment which is tilted horizontally and produces a horizontal image on the lateral view. The CT sections must be examined for the presence of a secondary sagittal line completely isolating the horizontally tilted fragment. The importance of the location of the fundamental fracture line, which is on the borderline between tilting and horizontalisation, suggests that pronation-supination of the foot is a factor in the causal mechanism of these fractures. A clear understanding of the three-dimensional position of the fragments and of their displacement, essentially defined by the location of the fracture line, is a prequisite before attempting surgical reduction of calcaneal fractures.

Calcaneus↗