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At least 721 records · Page 40Linked to original sources
PubMed1997

N-methyl-D-aspartate receptor 1 mRNA distribution in the central nervous system of the weakly electric fish Apteronotus leptorhynchus.

We have isolated a partial cDNA for the N-methyl-D-aspartate (NMDA) receptor 1 (NMDAR1) subunit from an Apteronotus leptorhynchus brain cDNA library. The A. leptorhynchus cDNA fragment, which corresponds to nucleotides 135-903 within the 5' region of the rat NR1 mRNA, encodes 252 amino acids that are >80% identical to the homologous segments of the rat, human, and duck NR1 proteins. RNAse protection assays revealed that the A. leptorhynchus NR1 mRNA was highly enriched in the forebrain and hypothalamus, with lesser amounts in the brainstem, and very low levels in the cerebellum. In situ hybridization also demonstrated that neurons in the pallial forebrain were highly enriched in NR1 transcripts. High levels of NR1 mRNA were found in pyramidal cells within the optic tectum and octavolateral regions. Pyramidal cells of the electrosensory lateral line lobe had the highest levels of expression, and the NR1 mRNA was found to be selectively enriched in their apical dendrites.

Amino Acid Sequence↗
PubMed1984

Central depletion of catecholamines--importance of hypertension and anesthesia.

The importance of the brain noradrenergic sympathetic nervous system in blood pressure control during anesthesia with halothane and enflurane was investigated in normotensive and hypertensive rats. Central noradrenergic neurons were destroyed by instillation of 6-hydroxydopamine (6-OHDA) into the cerebral ventricle of both normotensive Wistar rats and spontaneously hypertensive rats (SHR). One week later, arterial and venous lines were placed in the rats under anesthesia; the rats were allowed to recover; and blood pressure and plasma renin activity were measured while the rats were awake. Anesthesia then was induced with 1.3 vol% halothane (Wistar n = 8, Wistar 6-OHDA n = 10, SHR n = 8, SHR 6-OHDA n = 6) or 2.2 vol% enflurane (Wistar n = 6, Wistar 6-OHDA n = 10, SHR n = 8, SHR 6-OHDA n = 6). A control group (Wistar n = 10, Wistar 6-OHDA n = 6, SHR n = 8, SHR 6-OHDA n = 6) was treated identically, but remained unanesthetized throughout the experiment. The untreated normotensive and hypertensive rats received no intraventricular injections. After 1 hr of stable anesthesia, plasma renin activity was measured again, and saralasin, a competitive inhibitor of angiotensin II, was infused to determine the importance of the renin--angiotensin system in blood pressure control. Treatment with 6-OHDA resulted in a 60-90% depletion of norepinephrine in the medulla and hypothalamus. Normotensive Wistar rats treated with 6-OHDA responded to halothane and enflurane anesthesia in a manner similar to untreated normotensive rats. In contrast, hypertensive animals treated with 6-OHDA and then anesthetized with halothane had a significantly greater decrease in blood pressure than untreated hypertensive rats (100 +/- 4 mm Hg vs 125 +/- 4 mm Hg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

The evolution of quality assurance for intensity- modulated radiation therapy (IMRT): sequential tomotherapy.

PURPOSE: To identify the pertinent issues to be addressed in successfully implementing IMRT using sequential tomotherapy into clinical reality and presenting the maturation of quality assurance (QA) programs for both the delivery system and patient treatments that allow routine clinical use of the system. MATERIALS AND METHODS: Initially, a cubic phantom containing silver halide film was exposed to the entire treatment before patient treatment. The processed films were digitized with a laser densitometer and the dose distributions were compared with that generated by the planning system. Later, software that calculates the dose delivered to any phantom employing the intensity patterns developed in the inverse planning system for an individual patient was implemented for point checks of dose. A measurement phantom for use with this software was developed and evaluated on a large number of patients. Invasive fixation was used for all cranial patients initially. To use sequential tomotherapy for other sites and larger targets, noninvasive immobilization systems using two types of thermoplastic masks for cranial targets and reusable, evacuated body cradles were evaluated for positional accuracy and suitability for use with port films for patient QA. RESULTS: The program for equipment validation is divided into daily, weekly, and monthly programs that add only small amounts of time to routine QA programs. For the first 15 patients treated with this modality, the maximum dose measured on the film was within 5% of that predicted by the planning computer. The prescription isodose line was measured in the anteroposterior and lateral dimensions and the average discrepancy between measured and predicted was less than 2 mm. For an isodose line between 50% and 70% of the prescribed dose, the agreement was better than 3 mm. Success with the volume QA program was followed by a point check QA program that reduced the time required for individual patient QA from days to hours. Phantom measurements compared with computer predictions for 588 data points resulted in only 8% being outside a +/-5% criterion. These cases were identified and allow a further reduction in the frequency of tests. Thermoplastic mask materials have adequate restraint characteristics for use with the system and port films on 21 patients resulted in one standard deviation = 1.3 mm. Body cradles are less accurate and require more frequent port films. A QA system that reduces the frequency of port films was developed. CONCLUSIONS: The evolution of sequential tomotherapy in our department has been from a maximum of 3 cranial patients per day with invasive fixation to 60 patients per day for treatment of cranial, head-and-neck, and prostate tumors using different immobilization techniques. With proper preparation and refinement of tools used in commissioning and validation, sequential tomotherapy IMRT can become a routine clinical treatment modality.

Adenocarcinoma↗
PubMed2006

Compositions of maple sap microflora and collection system biofilms evaluated by scanning electron microscopy and denaturing gradient gel electrophoresis.

The bacterial microflora of maple sap and biofilms in collection system tubing were studied through the use of bacterial counts, scanning electron microscopy (SEM) of surfaces and the analysis of 16S rRNA gene by denaturing gradient gel electrophoresis (DGGE). Samples were taken at five times during the 2002 and 2003 seasons in order to follow the changes in the microflora of this complex ecosystem. Bacterial counts showed the growth of bacterial populations as the season advanced. These populations were mainly composed of psychrotrophic bacteria and Pseudomonas spp. SEM results confirmed the suspected presence of biofilms on the inner surfaces of tubing samples. Bacterial colonization and biofilm formation progressively increased during the season for both lateral and main line surfaces, and biofilms were mainly composed of rod shape bacteria. The bacterial microflora profiles obtained for sap and corresponding biofilm by DGGE showed up to 12 major bands. The Shannon-Weaver index of diversity (H) calculated from DGGE bands were statistically higher for sap samples compared to biofilm. The diversity index was relatively stable or increasing for lateral line sap and biofilm samples during the season while the diversity index for sap and biofilm samples of the main line showed a decreasing profile as the season progressed. Sequence analysis of major DGGE bands revealed the predominance of bacteria from the genera Pseudomonas, Rahnella and another, unidentified genus. The results describe the composition of sap collection system microflora as well as the formation of biofilms and will be useful for further studies on factors affecting maple product quality.

Acer↗
PubMed1997

Use of a hormone-sensitive (LNCaP) and a hormone-resistant (LNCaP-r) cell line in prostate cancer research.

BACKGROUND: In order to develop a hormone-resistant analog to the hormone sensitive cell-line LNCaP, different methods were tried. METHODS: After almost one year of continuous culture in RPMI-1640, containing a low concentration of androgens, the hormone sensitive cell-line LNCaP became hormone resistant and was named LNCaP-r. RESULTS: We used the LNCaP/LNCaP-r model system in order to study methods for the parenteral treatment of prostate carcinoma with estrogens, to study the mechanism of action of estramustine, and to identify markers useful as predictive tests for prostate carcinoma. CONCLUSIONS: A model system made up of the hormone sensitive prostate LNCaP cell-line and the hormone resistant LNCaP-r subline was developed and characterized. This system is, despite a number of limitations, easy to use as a first step to test different hypotheses that can be studied further in later clinical trials.

Androgens↗
PubMed1985

Visual conspicuity of a moving dot, horizontal line segment or vertical line segment.

The effect of varying the retinal eccentricity of a moving target on its conspicuity were explored for targets whose shape, orientation, size and luminance were the same as the stationary background elements. The target was a dot, horizontal line segment, or vertical line segment. The main results were: (1) conspicuity increased monotically as a function of velocity for all of the cases. (2) The rate of the increase of conspicuity slowed down at around a velocity between 0.6 and 0.8 deg/sec (break in slope). (3) For individual subjects, the size of conspicuity area for a dot was not so different from that for a horizontal line segment, but it was very different from that for a vertical line segment. (4) The position of the break in slope shifted upward or downward from one another but not laterally. The results indicate that the conspicuity was not due to the sum of the outputs in movingness analyzing system (MAS, Transient-channel) and displacement analyzing system (DAS, Sustained-channel), but due to one of them according to velocity of the moving element.

Fixation, Ocular↗
PubMed2006

Secreted inducers in vertebrate eye development: more functions for old morphogens.

Cell signaling molecules secreted from strategically localized positions coordinate cell behavior to enable progressive specification of embryonic tissues. These molecules converge on a few signaling pathways that are reiteratively used in different tissues at different times for generating cell type-specific patterns of gene expression. Although our current knowledge of the system is fragmentary, eye development seems to follow this general strategy. In line with this idea, recent studies have added new information on how Fgf and Wnt signaling participates in the formation of the eye field. In addition, later on in development, Fgf controls the onset of retinal neurogenesis and Shh and GDF11 control its feedback regulation.

Animals↗
PubMed2003

On-line overpressure thin-layer chromatographic separation and electrospray mass spectrometric detection of glycolipids.

On-line thin-layer chromatographic separation and electrospray mass spectrometry (TLC/ESI-MS) has been accomplished by direct linking of a commercial overpressure TLC instrument, OPLC 50, and a Q-TOF mass spectrometer. Mass spectrometric detection sensitivity and chromatographic resolution achieved by this configuration were assessed using acidic glycolipids as examples. Under the optimized conditions, a sensitivity of 5 pmol of glycosphingolipid was readily demonstrated for TLC/ESI-MS and 20 pmol for TLC/ESI-MS/MS production scanning to derive the saccharide sequence and long chain base/fatty acid composition of the ceramide. Initial preconditioning of TLC plates is necessary to achieve high sensitivity detection by reducing chemical background noise. Plates can be used repeatedly (at least 10 times) for analysis, although this may result in a minor reduction in TLC resolution. Following solvent development, separated components on the TLC plates can be detected in the conventional way by nondestructive staining or UV absorption or fluorescence and can be stored for on-line TLC/ESI-MS analysis at a later stage without reduction in mass spectrometric detection sensitivity and chromatographic resolution. Aspects for further improvement of OPLC instrumentation include use of narrower TLC plate dimensions and refined design of the eluate exit system.

Carbohydrate Conformation↗
PubMed2001

Primary structure and developmental expression of zebrafish sodium channel Na(v)1.6 during neurogenesis.

A zebrafish sodium channel cDNA encoding a 1949-amino acid polypeptide, Na(v)1.6, was isolated. Two transcripts were detected in zebrafish adult brain but not in cardiac or skeletal muscle. The RNase protection analysis confirmed the neural specificity of zebrafish Na(v)1.6 24 hours postfertilization (hpf) Na(v)1.6 was expressed in the trigeminal ganglion, anterior and posterior lateral line ganglia, rhombomeres, and Rohon-Beard neurons. This preferential localization suggests that Na(v)1.6 plays an important role in tactile sensitivity. The abundance of zebrafish Na(v) 1.6 mRNA in the central and peripheral nervous systems increased markedly between 48 and 72 hpf, during the maturation of the nervous system.

Amino Acid Sequence↗
PubMed1999

Migration from hierarchal storage management to ASM storage server: a case study.

The Department of Radiology at the University of Utah Hospitals and Clinics had to make a change from its current hierarchical storage management (HSM) system. The HSM software is the heart of any near-line data storage system and any change in this software affects all near-line and on-line data storage. In this case, over a terabyte of data had been migrated in more than 2 million files. The traditional method of reading in the old data and then writing it out to the new system was calculated to take more than 60 years. Here, we will examine the reasons for making such a radical change in the HSM used. We will also discuss why ASM (the new HSM software) was selected, and the performance improvements seen. A second, less difficult transition was made a few months later, of upgrading to a newer faster tape technology. The two types of tapes were incompatible, but the storage software and robotics used allowed for a peaceful coexistence during the transition. The transition from HSM to ASM was not a trivial task. It required a reasonable implementation/migration plan, which involved finding the correct resources and thinking outside the norm for solutions. All sites that have any amount of data stored in near-line devices will face similar conversions. This presentation should help in the event that a data conversion plan is not already in place.

Computer Systems↗
PubMed1993

Preoptic and hypothalamic neurons and the initiation of locomotion in the anesthetized rat.

Despite its insensate condition and apparent motoric depression, the anesthetized rat can provide useful information about the systems involved in locomotor initiation. The preparation appears to be particularly appropriate for the study of the appetitive locomotor systems and may be more limited for the study of the circuits involved in exploratory and defensive locomotion. In the anesthetized rat, pharmacological evidence indicates that the preoptic basal forebrain contains neurons which initiate locomotor stepping. Mapping with low levels of electrical stimulation indicates, but does not prove, that a region centered in the lateral preoptic area might be the location of these neurons. Several lines of evidence indicate that locomotor stepping elicited by electrical stimulation of the hypothalamus is mediated by neurons in the perifornical and lateral hypothalamus. Locomotor effects of hypothalamic stimulation persist in the absence of descending fibers of passage from the ipsilateral preoptic locomotor regions but are severely impaired by kainic acid lesions in the area of stimulation. Injections of glutamate into the perifornical and lateral hypothalamus elicit locomotor stepping at short latencies. Anatomical evidence suggests that the two regions are components of a network for appetitive locomotion. The recognition that multiple systems initiate locomotion both clarifies and complicates the study of locomotion. It provides a framework that incorporates disparate findings but it also underscores the need for increased attention to behavioral issues in studies of locomotor circuitry.

Anesthesia, General↗
PubMed2000

Gene transfer for neuroprotection in animal models of Parkinson's disease and amyotrophic lateral sclerosis.

Glial cell line-derived neurotrophic factor (GDNF) is a potent survival factor for motoneurons (MN) and dopaminergic (DA) neurons, neurons which selectively die in amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). GDNF gene delivery has been studied in rodent models of ALS and PD. In a mouse model of ALS, implantation of myoblasts retrovirally transduced with GDNF into hindlimb muscles at 6 weeks of age, i.e. prior to the onset of disease symptoms, increased the number of large MNs that maintained projections to treated muscles at 18 weeks of age. GDNF-treated mice also performed better on tests of motor function and had a delayed onset of disease. In a progressive degeneration rat model of PD, effects of in vivo GDNF gene therapy using an adenoviral vector (AdGDNF) were studied in young and aged rats. AdGDNF protected DA neurons against the neurotoxin, 6-hydroxydopamine (6-OHDA), and was effective whether injected either before or after 6-OHDA damage had commenced. However, if AdGDNF was injected prior to 6-OHDA, it was most effective in protecting against DA-dependent changes in the brain when injected near the terminals of the DA neurons. In contrast, if 6-OHDA damage had already commenced, AdGDNF was most effective if injected near the DA soma. These studies suggest that GDNF gene delivery into specific sites in the CNS or into muscle where MNs have access to secreted GDNF may slow the progression of PD and ALS, respectively. Neurotrophic factor gene therapy offers novel interventions not only for PD and ALS, but also other neurodegenerative diseases and injuries to the nervous system.

Amyotrophic Lateral Sclerosis↗
PubMed1998

Restricted expression of the neuronal intermediate filament protein plasticin during zebrafish development.

In the adult goldfish visual pathway, expression of the neuronal intermediate filament (nIF) protein plasticin is restricted to differentiating retinal ganglion cells (RGCs) at the margin of the retina. Following optic nerve injury, plasticin expression is elevated transiently in all RGCs coincident with the early stages of axon regeneration. These results suggest that plasticin may be expressed throughout the nervous system during the early stages of axonogenesis. To test this hypothesis, we analyzed plasticin expression during zebrafish (Danio rerio) neuronal development. By using immunocytochemistry and in situ hybridization, we found that plasticin is expressed in restricted subsets of early zebrafish neurons. Expression coincides with axon outgrowth in projection neurons that pioneer distinct axon tracts in the embryo. Plasticin is expressed first in trigeminal, Rohon-Beard, and posterior lateral line ganglia neurons, which are among the earliest neurons to initiate axonogenesis in zebrafish. Plasticin is expressed also in reticulospinal neurons and in caudal primary motoneurons. Together, these neurons establish the first behavioral responses in the embryo. Plasticin expression also coincides with initial RGC axonogenesis and progressively decreases after RGC axons reach the tectum. At later developmental stages, plasticin is expressed in a subset of the cranial nerves. The majority of plasticin-positive neurons are within or project axons to the peripheral nervous system. Our results suggest that plasticin subserves the changing requirements for plasticity and stability during axonal outgrowth in neurons that project long axons.

Animals↗
PubMed1994

Visual acuity and hemispheric asymmetries in pigeons.

Pigeons and domestic chicks tested under monocular conditions in pattern distinction tasks generally show higher discrimination performances with the right eye seeing. At least two different mechanisms could mediate this asymmetry: the dominance of the right eye could either be due to hemispheric differences in the cognitive operations performed during these tasks, or may reflect a lateralization in the spatial frequency discrimination capacity of the left and the right eye system. The aim of the present study was to decide between these two hypotheses. Therefore nine adult homing pigeons (Columba livia) were tested with the left or the right eye seeing in a visual acuity task using high-contrast square wave gratings. Visual acuity, defined as the spatial frequency at which the psychometric function crossed the 75% correct line was virtually identical for the two eyes with 6.6 for the left and 6.4 c/deg for the right eye. Thus, visual lateralization as demonstrated in various pattern discrimination tasks seems not to depend on asymmetries in acuity but probably reflects hemispheric differences in the visual processing mode.

Animals↗
PubMed1999

A novel transgenic technique that allows specific marking of the neural crest cell lineage in mice.

Neural crest cells are embryonic, multipotent stem cells that give rise to various cell/tissue types and thus serve as a good model system for the study of cell specification and mechanisms of cell differentiation. For analysis of neural crest cell lineage, an efficient method has been devised for manipulating the mouse genome through the Cre-loxP system. We generated transgenic mice harboring a Cre gene driven by a promoter of protein 0 (P0). To detect the Cre-mediated DNA recombination, we crossed P0-Cre transgenic mice with CAG-CAT-Z indicator transgenic mice. The CAG-CAT-Z Tg line carries a lacZ gene downstream of a chicken beta-actin promoter and a "stuffer" fragment flanked by two loxP sequences, so that lacZ is expressed only when the stuffer is removed by the action of Cre recombinase. In three different P0-Cre lines crossed with CAG-CAT-Z Tg, embryos carrying both transgenes showed lacZ expression in tissues derived from neural crest cells, such as spinal dorsal root ganglia, sympathetic nervous system, enteric nervous system, and ventral craniofacial mesenchyme at stages later than 9.0 dpc. These findings give some insights into neural crest cell differentiation in mammals. We believe that P0-Cre transgenic mice will facilitate many interesting experiments, including lineage analysis, purification, and genetic manipulation of the mammalian neural crest cells.

Animals↗
PubMed1981

Illusions of filled lateral and angular extent. The role of cortical feature detectors.

The common principle of the illusions found by Helmholtz and Botti is the overestimation of a filled extent. They differ in that Helmholtz's illusions of filled angular extent can be accounted for in terms of spatial two-line interactions, whereas Botti's illusions of filled lateral extent cannot. The former observation is consistent with the assumption of interacting orientation-detectors in the visual cortex. The Botti illusion probably depends on global computation in the visual system.

Humans↗
PubMed1980

The cerebral ventricles of the dog. I. Ultrastructural features of supraependymal cells during the inflammatory response.

The present investigation examined the ependymal linings of the cerebral ventricles of the dog following a single intracisternal injection of the viable antigen, bacillus Calmette-Guerin (BCG). One or 3 days following the injection of BCG, animals were perfused with buffered aldehydes. Portions of the linings of the lateral, third and fourth cerebral ventricles were removed and routinely prepared for scanning and transmission electron microscopy. Following BCG injection, a tremendous increase in the number of supraependymal cells is apparent throughout the entire cerebral ventricular system. Especially high concentrations of cells were observed on the ependyma overlying the following regions; the caudate nucleus, in the lateral ventricles; the interthalamic adhesion, lateral walls and floor of the third ventricle; lateral margin of the floor, lateral apertures and median sulcus of the fourth ventricle. The supraependymal cell population of infected animals was composed of macrophages, B lymphocytes, neutrophils, and lymphoblasts. Macrophages were found in highest concentration within these supraependymal cell populations. Furthermore, large aggregates of macrophages were observed on the ependyma overlying the interthalamic adhesion of the third ventricle and median sulcus of the fourth ventricle. It was suggested that these clusters may represent the early development of epithelioid granulomas.

Animals↗
PubMed2002

Visuomotor control within a distributed parieto-frontal network.

The aim of this functional magnetic resonance imaging study was to investigate differences in visuomotor control with increasing task complexity. Twelve right-handed volunteers were asked to perform their signature under different degrees of visual control: internally generated movement with closed eyes, signing with open eyes, tracking the line of the projected signature forwards, and tracking the line of the projected signature backwards. There was a gradual onset and disappearance of activation within a distributed network. Parietal, lateral and medial frontal brain areas were activated during all conditions, confirming the involvement of a parieto-frontal system. The weight of activation shifted with increasing task complexity. Internally generated movements activated predominantly the inferior parietal lobule and the ventral premotor cortex, as well as the rostral cingulate area, pre-supplementary motor area (pre-SMA) and SMA proper. Opening the eyes reduced SMA and cingulate activation and activated increasingly the occipito-parietal areas with higher task complexity. Visually guided movements produced an activation predominantly in the superior parietal lobule and dorsal premotor cortex. This study bridges human activation studies with the results of neurophysiological studies with monkeys. It confirms a gradual transition of visuomotor control with increasing task complexity within a distributed parieto-frontal network.

Adult↗