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2.
Colorectal Dis ; 19(1): O54-O65, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27886434

ABSTRACT

AIM: Imaging for pelvic floor defaecatory dysfunction includes defaecation proctography. Integrated total pelvic floor ultrasound (transvaginal, transperineal, endoanal) may be an alternative. This study assesses ultrasound accuracy for the detection of rectocele, intussusception, enterocele and dyssynergy compared with defaecation proctography, and determines if ultrasound can predict symptoms and findings on proctography. Treatment is examined. METHOD: Images of 323 women who underwent integrated total pelvic floor ultrasound and defaecation proctography between 2011 and 2014 were blindly reviewed. The size and grade of rectocele, enterocele, intussusception and dyssynergy were noted on both, using proctography as the gold standard. Barium trapping in a rectocele or a functionally significant enterocele was noted on proctography. Demographics and Obstructive Defaecation Symptom scores were collated. RESULTS: The positive predictive value of ultrasound was 73% for rectocele, 79% for intussusception and 91% for enterocele. The negative predictive value for dyssynergy was 99%. Agreement was moderate for rectocele and intussusception, good for enterocele and fair for dyssynergy. The majority of rectoceles that required surgery (59/61) and caused barium trapping (85/89) were detected on ultrasound. A rectocele seen on both transvaginal and transperineal scanning was more likely to require surgery than if seen with only one mode (P = 0.0001). If there was intussusception on ultrasound the patient was more likely to have surgery (P = 0.03). An enterocele visualized on ultrasound was likely to be functionally significant on proctography (P = 0.02). There was, however, no association between findings on imaging and symptoms. CONCLUSION: Integrated total pelvic floor ultrasound provides a useful screening tool for women with defaecatory dysfunction such that defaecatory imaging can avoided in some.


Subject(s)
Constipation/diagnostic imaging , Defecography/methods , Endosonography/methods , Pelvic Floor Disorders/diagnostic imaging , Pelvic Floor/diagnostic imaging , Adult , Aged , Aged, 80 and over , Ataxia/complications , Ataxia/diagnostic imaging , Ataxia/physiopathology , Barium , Constipation/etiology , Constipation/physiopathology , Contrast Media , Defecation/physiology , Female , Hernia/complications , Hernia/diagnostic imaging , Hernia/physiopathology , Humans , Intussusception/complications , Intussusception/diagnostic imaging , Intussusception/physiopathology , Middle Aged , Pelvic Floor/physiopathology , Pelvic Floor Disorders/complications , Pelvic Floor Disorders/physiopathology , Predictive Value of Tests , Rectocele/complications , Rectocele/diagnostic imaging , Rectocele/physiopathology , Severity of Illness Index , Single-Blind Method
3.
Rev Sci Instrum ; 85(11): 115001, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25430138

ABSTRACT

Acceleration in development of additional conventional hydropower requires tools and methods to perform laboratory and in-field validation of turbine performance and fish passage claims. The new-generation Sensor Fish has been developed with more capabilities to accommodate a wider range of users over a broader range of turbine designs and operating environments. It provides in situ measurements of three-dimensional (3D) linear accelerations, 3D rotational velocities, 3D orientation, pressure, and temperature at a sampling frequency of 2048 Hz. It also has an automatic floatation system and built-in radio-frequency transmitter for recovery. The relative errors of the pressure, acceleration, and rotational velocity were within ±2%, ±5%, and ±5%, respectively. The accuracy of orientation was within ±4° and accuracy of temperature was ±2 °C. The new-generation Sensor Fish is becoming a major technology and being deployed for evaluating the conditions for fish passage of turbines or other hydraulic structures in both the United States and several other countries.

4.
J Colloid Interface Sci ; 400: 135-9, 2013 Jun 15.
Article in English | MEDLINE | ID: mdl-23570870

ABSTRACT

Motivated by the process of inkjet printing of electronics, we study experimentally and theoretically the processes limiting the printing of sharply defined, equilibrium corners. Using a non-volatile ionic liquid, we inkjet print squares with rounded corners on a substrate of roughened, display-grade glass. We show experimentally that with increasing roughness, corner radius decreases, allowing more precisely defined features to be printed. To interpret these results in terms of contact-angle hysteresis (difference between the advancing and retreating contact angles θA and θR), we implement the following model with the Surface Evolver program. With drop volume fixed, we minimize drop surface energy subject to a prescribed contact line. We identify θA and θR as the minimum and maximum contact angles around the drop perimeter. We find that with decreasing corner fidelity, contact-angle hysteresis also decreases. We are thus able to infer θR from the corner radius of printed features. We conclude that increasing contact-angle hysteresis allows the printing of more precisely defined features.

5.
Langmuir ; 28(48): 16711-23, 2012 Dec 04.
Article in English | MEDLINE | ID: mdl-23110647

ABSTRACT

Pattern printing techniques have advanced rapidly in the past decade, driven by their potential applications in printed electronics. Several printing techniques have realized printed features of 10 µm or smaller, but unfortunately, they suffer from disadvantages that prevent their deployment in real applications; in particular, process throughput is a significant concern. Direct gravure printing is promising in this regard. Gravure printing delivers high throughput and has a proven history of being manufacturing worthy. Unfortunately, it suffers from scalability challenges because of limitations in roll manufacturing and limited understanding of the relevant printing mechanisms. Gravure printing involves interactions between the ink, the patterned cylinder master, the doctor blade that wipes excess ink, and the substrate to which the pattern is transferred. As gravure-printed features are scaled, the associated complexities are increased, and a detailed study of the various processes involved is lacking. In this work, we report on various gravure-related fluidic mechanisms using a novel highly scaled inverse direct gravure printer. The printer allows the overall pattern formation process to be studied in detail by separating the entire printing process into three sequential steps: filling, wiping, and transferring. We found that pattern formation by highly scaled gravure printing is governed by the wettability of the ink to the printing plate, doctor blade, and substrate. These individual functions are linked by the apparent capillary number (Ca); the printed volume fraction (φ(p)) of a feature can be constructed by incorporating these basis functions. By relating Ca and φ(p), an optimized operating point can be specified, and the associated limiting phenomena can be identified. We used this relationship to find the optimized ink viscosity and printing speed to achieve printed polymer lines and line spacings as small as 2 µm at printing speeds as high as ∼1 m/s.

6.
Langmuir ; 26(19): 15686-93, 2010 Oct 05.
Article in English | MEDLINE | ID: mdl-20825207

ABSTRACT

Inkjet printing of precisely defined structures is critical for the realization of a range of printed electronics applications. We develop and demonstrate a methodology to optimize the inkjet printing of two-dimensional, partially wetting films. When printed inks have a positive retreating contact angle, we show that any fixed spacing is ineffective for printing two-dimensional features. With fixed spacing, the bead contact angle begins large, leading to a bulging overflow of its intended footprint. Each additional line reduces the bead contact angle, eventually leading to separation of the bead. We propose a printing scheme that adjusts the line-to-line spacing to maintain a bead's contact angle between its advancing and retreating values as it is printed. Implementing this approach requires an understanding of the two-dimensional bead surface and compensation for evaporation during the print. We derive an analytic equation for the bead's surface with pinned contact lines and use an empirical fit for mass loss due to evaporation. Finally, we demonstrate that enhanced contact angle hysteresis, achieved by preprinting a feature's border, leads to better corner definition.

7.
Vet Microbiol ; 120(1-2): 184-91, 2007 Feb 25.
Article in English | MEDLINE | ID: mdl-17110059

ABSTRACT

A total of 30 British and 30 Spanish Haemophilus parasuis isolates were tested for their susceptibility to 19 of the antimicrobials currently used in swine practice with a broth microdilution method in order to know the emergence of resistance against these compounds in this porcine pathogen. All the British isolates were susceptible to penicillin, ceftiofur, erythromycin, tilmicosin, enrofloxacin, and florfenicol, and most of them were susceptible to the remaining antimicrobials (the highest resistance rate found was of 20% to neomycin). In contrast, all the Spanish isolates were susceptible exclusively to florfenicol, and high proportions of resistance were encountered for penicillin, ampicillin, oxytetracycline, erythromycin, tilmicosin, tiamulin and trimethoprim+sulphamethoxazole; in addition, a bimodal or multimodal distribution, or tailing of Spanish isolates over the MIC range was observed for clindamycin, sulphonamides and tylosine tartrate, suggesting the development of acquired resistance. In addition, several multiresistance patterns were found among the Spanish isolates, 23.3% of them being resistant to at least eight antimicrobials, the same rate as that encountered for those being susceptible to all antimicrobials tested. This study showed that in general British H. parasuis isolates are susceptible to antimicrobial agents routinely used for treatment of porcine respiratory diseases; however, the Spanish isolates need a more continuous surveillance of their susceptibility patterns.


Subject(s)
Anti-Infective Agents/pharmacology , Haemophilus Infections/veterinary , Haemophilus parasuis/drug effects , Swine Diseases/microbiology , Swine/microbiology , Animals , Drug Resistance, Bacterial , Haemophilus Infections/microbiology , Haemophilus parasuis/isolation & purification , Microbial Sensitivity Tests , Spain , United Kingdom
8.
Mol Ecol ; 14(11): 3395-405, 2005 Oct.
Article in English | MEDLINE | ID: mdl-16156811

ABSTRACT

A growing literature now documents the presence of fine-scale genetic structure in wild vertebrate populations. Breeding population size, levels of dispersal and polygyny--all hypothesized to affect population genetic structure--are known to be influenced by ecological conditions experienced by populations. However the possibility of temporal or spatial variation in fine-scale genetic structure as a result of ecological change is rarely considered or explored. Here we investigate temporal variation in fine-scale genetic structure in a red deer population on the Isle or Rum, Scotland. We document extremely fine-scale spatial genetic structure (< 100 m) amongst females but not males across a 24-year study period during which resource competition has intensified and the population has reached habitat carrying capacity. Based on census data, adult deer were allocated to one of three subpopulations in each year of the study. Global F(ST) estimates for females generated using these subpopulations decreased over the study period, indicating a rapid decline in fine-scale genetic structure of the population. Global F(ST) estimates for males were not different from zero across the study period. Using census and genetic data, we illustrate that, as a consequence of a release from culling early in the study period, the number of breeding females has increased while levels of polygyny have decreased in this population. We found little evidence for increasing dispersal between subpopulations over time in either sex. We argue that both increasing female population size and decreasing polygyny could explain the decline in female population genetic structure.


Subject(s)
Deer/genetics , Genetics, Population , Population Density , Sexual Behavior, Animal/physiology , Animals , Deer/physiology , Female , Genotype , Geography , Longitudinal Studies , Microsatellite Repeats/genetics , Population Dynamics , Scotland , Sex Factors
9.
Paediatr Anaesth ; 13(8): 681-4, 2003 Oct.
Article in English | MEDLINE | ID: mdl-14535905

ABSTRACT

BACKGROUND: The aim of this study was to assess whether a noninvasive imaging technique such as ultrasound could visualize an epidural catheter in the epidural space in children. METHODS: Following local ethics committee approval and informed parental consent a pilot study of 12 cases was performed. Children undergoing major surgery requiring epidural analgesia were recruited. All catheters were introduced via the lumbar region. All children were scanned within 24 h of epidural insertion by consultant paediatric radiologists. If the catheter was identified in the epidural space then an attempt was made to visualize the entire length of the catheter. RESULTS: The epidural catheter was detected in nine of 12 patients. All of these were less than 6 months old. The entire length of the catheter was visualized in five of the nine patients. It was possible to estimate the most cephalad level of the catheter in seven of the nine patients. This was in the thoracic region in all cases and an appropriate level for the intended surgical procedure. It was not possible to precisely identify the tip of the catheter as a distinct entity using ultrasound. CONCLUSION: This study shows that it is possible to visualize an epidural catheter in the epidural space in children under 6 months of age using ultrasound.


Subject(s)
Analgesia, Epidural/instrumentation , Catheters, Indwelling , Age Factors , Epidural Space/diagnostic imaging , Female , Humans , Infant , Infant, Newborn , Male , Pilot Projects , Sensitivity and Specificity , Ultrasonography
10.
Arch Dis Child ; 87(4): 331-2, 2002 Oct.
Article in English | MEDLINE | ID: mdl-12244011

ABSTRACT

We compared the outcome of children with empyema managed either through thoracotomy with pleural debridment, conventional stiff chest drain, or pigtail chest drain. Compared to conventional drain, children who received either thoracotomy or pigtail catheters had a significantly decreased period of drain in situ, were afebrile earlier, were clinically improved earlier, and were discharged earlier.


Subject(s)
Catheterization, Peripheral/instrumentation , Drainage/instrumentation , Empyema, Pleural/therapy , Child , Child, Preschool , Debridement , Empyema, Pleural/surgery , Humans , Infant , Retrospective Studies , Thoracotomy , Treatment Outcome
11.
Arch Virol ; 147(5): 961-79, 2002 May.
Article in English | MEDLINE | ID: mdl-12021867

ABSTRACT

Previously, we have shown that apoptosis induced by influenza virus was inhibited by an anti-neuraminidase compound [4-guanidino-2, 3-dehydro-N-acetylneuraminic acid (GG167; Relenza; Zanamivir)], which does not enter cells, and acts at the attachment/entry phase of virus replication. Furthermore, a virulent virus, clone 7a, induced greater levels of apoptosis than the attenuated A/Fiji and had greater neuraminidase (NA) activity. To confirm more directly that NA induces apoptosis, the NA of clone 7a and A/Fiji was expressed fused to the Herpes simplex virus tegument coat protein VP22, transfected into HeLa cells and the level of apoptosis determined. VP22 translocates between cells via the medium thus allowing expressed proteins to transfer to a larger number of cells than those originally transfected. Clone 7a NA fused to VP22 induced a significant level of apoptosis whereas A/Fiji NA/VP22 did not, confirming that NA activity is an important determinant of apoptosis acting during fusion protein translocation between cells. Furthermore, the induction of apoptosis was abrogated by antibody to transforming growth factor-beta, which is activated by NA. This approach also showed that VP22/NS1 proteins of both clone 7a and A/Fiji induced apoptosis when expressed alone but inhibited double stranded RNA-induced apoptosis suggesting that this protein may have a dual mode of action. Also, the M1 and M2 proteins of both viruses induced apoptosis but their NP proteins did not.


Subject(s)
Apoptosis , Neuraminidase/physiology , Orthomyxoviridae/enzymology , Phosphoproteins/genetics , Recombinant Fusion Proteins/physiology , Simplexvirus/chemistry , Viral Nonstructural Proteins/physiology , Viral Structural Proteins/genetics , Cloning, Molecular , Genetic Vectors , HeLa Cells , Humans , Influenza A virus/genetics , Influenza A virus/physiology , Microscopy, Confocal , Molecular Sequence Data , Neuraminidase/genetics , Transfection , Transforming Growth Factor beta/metabolism , Viral Matrix Proteins/genetics , Viral Matrix Proteins/physiology , Viral Nonstructural Proteins/genetics
12.
J Colloid Interface Sci ; 254(2): 346-54, 2002 Oct 15.
Article in English | MEDLINE | ID: mdl-12702407

ABSTRACT

We consider a two-dimensional model of a vapor bubble between two horizontal parallel boundaries held at different temperatures. When the temperatures are constant, a steady state can be achieved such that evaporation near the contact lines at the hot bottom plate is balanced by condensation in colder areas of the interface near the top. The dynamic response of the bubble is probed by treating the case of time-dependent wall temperatures. For periodic modulations of the wall temperature the bubble oscillates about the steady state. In order to describe such time-dependent behavior we consider the limit of small capillary number, in which the effects of heat and mass transfer are significant only near the contact lines at the bottom plate and in a small region near the top. When the bottom temperature is modulated and the top temperature is held fixed, the amplitude of forced oscillations is constant for low-frequency modulations and then rapidly decays in the high-frequency regime. When the top temperature is modulated with fixed bottom temperature, the dynamic-response curve is flat in the low-frequency regime as well, but it also flattens out when the frequency is increased. This shape of the response curve is shown to be the result of the nonmonotonic behavior of the thickness of the liquid film between the bubble interface and the top plate: when the temperature is decreased, the film thickness increases rapidly, but then slowly decays to a value which is smaller than the initial thickness. The dynamic response is also studied as a function of the forcing amplitude.

14.
Pediatr Radiol ; 31(9): 631-3, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11512002

ABSTRACT

Primary malignant rhabdoid tumour of the central nervous system is a rare neoplasm affecting children. We present a pathologically proven case, which was initially referred to the paediatric surgeons as a sebaceous cyst, and highlights the importance of imaging prior to surgery of potentially innocuous scalp lesions. Imaging features on CT and MRI are presented, which show bony involvement not previously reported in the literature.


Subject(s)
Brain Neoplasms/diagnosis , Rhabdoid Tumor/diagnosis , Brain Neoplasms/diagnostic imaging , Child , Female , Humans , Magnetic Resonance Imaging , Radionuclide Imaging , Rhabdoid Tumor/diagnostic imaging , Rhabdoid Tumor/secondary , Skull Neoplasms/diagnostic imaging , Skull Neoplasms/secondary , Tomography, X-Ray Computed
15.
J Neurochem ; 77(5): 1237-47, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11389174

ABSTRACT

Studies of gamma-aminobutyric acid (GABA)(B) receptor function in heterologous cell systems have suggested that expression of two distinct seven transmembrane G-protein coupled receptor subunits is necessary for receptor activation and signal transduction. Some results suggest that both receptor proteins must be inserted into the plasma membrane to create heterodimers; however, it is possible that subunit monomers or homodimers are functional in cells which constitutively express GABA(B) receptors. A new pituitary intermediate lobe melanotrope cell clone (mIL tsA58) has been isolated which constitutively expresses GABA(B), D(2) and corticotrophin releasing factor receptors. Here, we report on characterization of the GABA(B) receptors. Solution hybridization-nuclease protection assays reveal the presence of GABA(B(1)) and GABA(B(2)) transcripts. Western blots show GABA(B(1a)) and one of two GABA(B(2)) proteins. Addition of the GABA(B) agonist baclofen to cultured mIL-tsA58 (mIL) cells inhibits high voltage activated Ca(2+) channels, as measured by agonist-induced inhibition of the K(+)-depolarization-stimulated increase in Ca(2+) influx. CGP55845, a GABA(B) antagonist, blocks the response to baclofen. Knockdown of either GABA(B(1)) or GABA(B(2)) subunits with selective antisense oligodeoxynucleotides reduced GABA(B) protein levels and completely abolished the GABA(B) receptor response in the mIL cells. Taken together, these results indicate that functionally active GABA(B) receptors in mIL cells require the constitutive expression of both GABA(B) genes. This is a physiologic validation of results from recombinant overexpression in naive cells and shows that the mIL cell line is a useful model for studying GABA(B) receptor expression, regulation and function.


Subject(s)
Gene Expression Regulation/genetics , Pituitary Gland/metabolism , Receptors, GABA-B/biosynthesis , Receptors, GABA-B/genetics , Animals , Blotting, Western , Calcium/metabolism , Calcium Channel Blockers/pharmacology , Cell Line , GABA Agonists/pharmacology , Gene Expression Regulation/drug effects , Ion Channel Gating/drug effects , Mice , Nuclease Protection Assays , Oligonucleotides, Antisense/pharmacology , Pituitary Gland/cytology
16.
J Pharmacol Exp Ther ; 298(1): 15-24, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11408520

ABSTRACT

Gabapentin (Neurontin, Pfizer Global R & D) is a novel anticonvulsant, antihyperalgesic, and antinociceptive agent with a poorly understood mechanism of action. In this study, we show that gabapentin (EC50 2 microM) inhibited up to 70 to 80% of the total K+-evoked Ca2+ influx via voltage-dependent calcium channels (VD-CCs) in a mouse pituitary intermediate melanotrope clonal mIL-tsA58 (mIL) cell line. mIL cells endogenously express only gamma-aminobutyric acid type B (GABA(B)) gb1a-gb2 receptors. Moreover, activity of the agonist gabapentin was dose dependently and completely blocked with the GABA(B) antagonist CGP55845 and was nearly identical to the prototypic GABA(B) agonist baclofen in both extent and potency. Antisense knockdown of gb1a also completely blocked gabapentin activity, while gb1b antisense and control oligonucleotides had no effect, indicating that gabapentin inhibition of membrane Ca2+ mobilization in mIL cells was dependent on a functional GABA(B) (gb1a-gb2) heterodimer receptor. In addition, during combined whole cell recording and multiphoton Ca2+ imaging in hippocampal neurons in situ, gabapentin significantly inhibited in a dose-dependent manner subthreshold soma depolarizations and Ca2+ responses evoked by somatic current injection. Furthermore, gabapentin almost completely blocked Ca2+ action potentials and Ca2+ responses elicited by suprathreshold current injection. However, larger current injection overcame this inhibition of Ca2+ action potentials suggesting that gabapentin did not predominantly affect L-type Ca2+ channels. The depressant effect of gabapentin on Ca2+ responses was coupled to the activation of neuronal GABA(B) receptors since they were blocked by CGP55845, and baclofen produced similar effects. Thus gabapentin activation of neuronal GABA(B) gb1a-gb2 receptors negatively coupled to VD-CCs can be a potentially important therapeutic mechanism of action of gabapentin that may be linked to inhibition of neurotransmitter release in some systems.


Subject(s)
Acetates/pharmacology , Amines , Analgesics/pharmacology , Anticonvulsants/pharmacology , Calcium Channels/drug effects , Cyclohexanecarboxylic Acids , GABA-B Receptor Agonists , Pyramidal Cells/drug effects , gamma-Aminobutyric Acid , Animals , Baclofen/pharmacology , Calcium Channels/physiology , Calcium Signaling/drug effects , Calcium Signaling/physiology , GABA Agonists/pharmacology , Gabapentin , Hippocampus/drug effects , Hippocampus/physiology , Male , Mice , Mice, Transgenic , Pyramidal Cells/physiology , Rats , Rats, Sprague-Dawley , Receptors, GABA-B/physiology
17.
J Biol Chem ; 276(16): 12660-6, 2001 Apr 20.
Article in English | MEDLINE | ID: mdl-11152678

ABSTRACT

We examined the biosynthesis and post-translational processing of the brain-derived neurotrophic factor precursor (pro-BDNF) in cells infected with a pro-BDNF-encoding vaccinia virus. Metabolic labeling, immunoprecipitation, and SDS-polyacrylamide gel electrophoresis reveal that pro-BDNF is generated as a 32-kDa precursor that is N-glycosylated and glycosulfated on a site, within the pro-domain. Some pro-BDNF is released extracellularly and is biologically active as demonstrated by its ability to mediate TrkB phosphorylation. The precursor undergoes N-terminal cleavage within the trans-Golgi network and/or immature secretory vesicles to generate mature BDNF (14 kDa). Small amounts of a 28-kDa protein that is immunoprecipitated with BDNF antibodies is also evident. This protein is generated in the endoplasmic reticulum through N-terminal cleavage of pro-BDNF at the Arg-Gly-Leu-Thr(57)- downward arrow-Ser-Leu site. Cleavage is abolished when Arg(54) is changed to Ala (R54A) by in vitro mutagenesis. Blocking generation of 28-kDa BDNF has no effect on the level of mature BDNF and blocking generation of mature BDNF with alpha(1)-PDX, an inhibitor of furin-like enzymes, does not lead to accumulation of the 28-kDa form. These data suggest that 28-kDa pro-BDNF is not an obligatory intermediate in the formation of the 14-kDa form in the constitutive secretory pathway.


Subject(s)
Brain-Derived Neurotrophic Factor/biosynthesis , Brain-Derived Neurotrophic Factor/metabolism , Hippocampus/metabolism , Neurons/metabolism , Protein Precursors/metabolism , Protein Processing, Post-Translational , Amino Acid Sequence , Animals , Brain-Derived Neurotrophic Factor/genetics , Brain-Derived Neurotrophic Factor/pharmacology , COS Cells , Cell Line , Chlorocebus aethiops , Embryo, Mammalian , Glycoside Hydrolases , Glycosylation , Humans , Mice , Molecular Sequence Data , Mutagenesis, Site-Directed , Neuroglia/metabolism , Phosphorylation , Protein Precursors/biosynthesis , Protein Precursors/genetics , Receptor, trkB/drug effects , Receptor, trkB/physiology , Recombinant Proteins/biosynthesis , Recombinant Proteins/metabolism , Transfection , Vaccinia virus/genetics
18.
J Neurosci ; 20(11): 4059-68, 2000 Jun 01.
Article in English | MEDLINE | ID: mdl-10818141

ABSTRACT

Hippocampal neurons release nerve growth factor (NGF) through the constitutive secretory pathway, thus allowing the protein to be continuously available for promoting nerve cell survival. In contrast, hippocampal neurons use the regulated secretory pathway to process brain-derived neurotrophic factor (BDNF), which alters synaptic activity when released acutely from dense-core vesicles. Thus, understanding how neurons sort and deliver neurotrophins may provide clues to their functions in brain. In this study, we monitored the processing and delivery of neurotrophin-3 (NT-3). Pulse-chase studies, immunocytochemistry, and secretagogue-induced release experiments were performed on cultured hippocampal neurons and AtT-20 cells infected with vaccinia viruses encoding the NT-3 precursor (pro-NT-3). Results show that most newly synthesized NT-3 is released through the constitutive secretory pathway as a result of furin-mediated endoproteolytic cleavage of pro-NT-3 in the trans-Golgi network. Pro-NT-3 can also be diverted into the regulated secretory pathway when cells are treated with alpha1-PDX, a selective inhibitor of furin-like enzymes, or when pro-NT-3 expression is increased by transient transfection methods. In cells coinfected with viruses coding for pro-NT-3 and pro-BDNF, NT-3 is sorted into the regulated pathway, stored in secretory granules, and released in response to extracellular cues together with BDNF, apparently as a result of heterodimerization, as suggested by coimmunoprecipitation data. Taken together, these data show that sorting of the NT-3 precursor can occur in both the constitutive and regulated secretory pathways, which is consistent with NT-3 having both survival-promoting and synapse-altering functions.


Subject(s)
Brain-Derived Neurotrophic Factor/biosynthesis , Hippocampus/physiology , Neurons/physiology , Neurotrophin 3/biosynthesis , Neurotrophin 3/physiology , Animals , COS Cells , Cell Survival/physiology , Cells, Cultured , Hippocampus/cytology , Hippocampus/metabolism , Immunohistochemistry , Mice , Microscopy, Confocal , Neurons/metabolism , Neurons/ultrastructure , Neurotrophin 3/genetics , Precipitin Tests , Transfection/genetics , Vaccinia virus/genetics , alpha 1-Antitrypsin/pharmacology
19.
J Neurosci ; 20(1): 274-82, 2000 Jan 01.
Article in English | MEDLINE | ID: mdl-10627605

ABSTRACT

Brain-derived neurotrophic factor (BDNF) is transported anterogradely in neurons of the CNS and can be released by activity-dependent mechanisms to regulate synaptic plasticity. However, few neural networks have been identified in which the production, transport, and effects of BDNF on postsynaptic neurons can be analyzed in detail. In this study, we have identified such a network. BDNF has been colocalized by immunocytochemistry with tyrosine hydroxylase (TH) in nerve fibers and nerve terminals within the lateral septum of rats. BDNF-containing nerve fibers terminate on a population of calbindin-containing neurons in lateral septum that contain TrkB, the high-affinity receptor for BDNF. Overexpression of BDNF in noradrenergic neurons increased levels of calbindin in septum, as well as in whole-brain lysates. Septal levels of calbindin and BDNF partially decreased after unilateral lesions of the medial forebrain bundle (MFB), induced with 6-hydroxydopamine, a treatment that abolished TH staining. These data suggest that BDNF is anterogradely transported within the MFB in catecholaminergic neurons arising from brainstem nuclei. To determine whether BDNF affects the production of calbindin in lateral septal neurons directly, we tested the effects of BDNF on cultures of septal neurons from embryonic day 16-17 rats. BDNF promoted the expression of calbindin, as well as the arborization of calbindin-containing neurons, but BDNF had no effect on cell division or survival. Together, these results suggest that BDNF, anterogradely transported in catecholaminergic neurons, regulates calbindin expression within the lateral septum.


Subject(s)
Brain-Derived Neurotrophic Factor/genetics , Neurons/chemistry , Presynaptic Terminals/chemistry , S100 Calcium Binding Protein G/analysis , Septal Nuclei/cytology , Age Factors , Animals , Axonal Transport/physiology , Brain-Derived Neurotrophic Factor/analysis , Brain-Derived Neurotrophic Factor/metabolism , Calbindins , Cells, Cultured , Dopamine beta-Hydroxylase/genetics , Female , Gene Expression Regulation, Enzymologic , Mice , Mice, Transgenic , Nerve Fibers/chemistry , Nerve Fibers/enzymology , Neurons/enzymology , Neurons/ultrastructure , Norepinephrine/physiology , Oxidopamine , Phenotype , Pregnancy , Promoter Regions, Genetic/physiology , Rats , Rats, Sprague-Dawley , Sympatholytics , Tyrosine 3-Monooxygenase/analysis
20.
J Neurochem ; 73(6): 2375-82, 1999 Dec.
Article in English | MEDLINE | ID: mdl-10582596

ABSTRACT

The dopamine D2 receptor belongs to the serpentine superfamily of receptors, which have seven transmembrane segments and activate G proteins. D2 receptors are known to be linked, through Galpha(o)- and Galpha(i)-containing G proteins, to several signaling pathways in neuronal and secretory cells, including inhibition of adenylyl cyclase and high voltage-activated Ca2+ channels (HVA-CCs). The dopamine D2 receptor exists in two alternatively spliced isoforms, "long" and "short" (D2L, and D2S, respectively), which have identical ligand binding sites but differ by 29 amino acids in the third intracellular loop, the proposed site for G protein interaction. This has led to the speculation that the two isoforms may interact with different G proteins. We have transfected the AtT20 cell line with either D2L (KCL line) or D2S (KCS line) to facilitate experimentation on the individual isoforms. Both lines show dopamine agonist-dependent inhibition of Q-type HVA-CCs. We combined G protein antisense knock-down studies with multiwavelength fluorescence video microscopy to measure changes in HVA-CC inhibition to investigate the possibility of differential G protein coupling to this inhibition. The initial, rapid, K+ depolarization-induced increase in intracellular Ca2+ concentration is due to influx through HVA-CCs. Our studies reveal that both D2 isoforms couple to Galpha(o) to partially inhibit this influx. However, D2L also couples to Galpha(i)3, whereas D2S couples to Galpha(i)2. These data support the hypothesis of differential coupling of D2 receptor isoforms to G proteins.


Subject(s)
Calcium Channel Blockers , Calcium/metabolism , GTP-Binding Proteins/physiology , Protein Isoforms/metabolism , Receptors, Dopamine D2/metabolism , Action Potentials/drug effects , Adenylate Cyclase Toxin , Animals , DNA, Antisense/pharmacology , GTP-Binding Proteins/antagonists & inhibitors , Ion Transport , Mice , Microscopy, Fluorescence , Microscopy, Video , Neoplasm Proteins/physiology , Pituitary Neoplasms/pathology , Potassium/metabolism , Potassium/pharmacology , Protein Binding , Protein Isoforms/genetics , Receptors, Dopamine D2/genetics , Recombinant Fusion Proteins/metabolism , Transfection , Tumor Cells, Cultured , Virulence Factors, Bordetella/pharmacology
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