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PubMed1976

The acetylcholine sensitivity of the surface membrane of multiply-innervated parasympathetic ganglion cells in the mudpuppy before and after partial denervation.

1. The surface chemosensitivity to iontophoretically applied acetylcholine (ACh) of single nerve cells in the cardiac ganglion of the mudpuppy was examined. 2. Some synapses on the neurones can be recognized in the living preparation with differential interference contrast optics. Identified synaptic regions of the ganglion cells were more sensitive to ACh than were other areas. The mean sensitivity of synaptic areas was 509 mV/nC, but that of random spots on the cell surface (which were mainly non-synaptic) was only 190 mV/nC. The mean rise time of ACh responses at synapses was 23 msec and at random spots was 36 msec. These data suggest that the density of ACh receptors is highest under the synapses on the post-synaptic membrane. 3. When some, but not all, of the presynaptic terminals on the ganglion cells are destroyed by cutting the vagus nerve, the sensitivity of the entire surface membrane to applied ACh increases. This increase in sensitivity reaches a maximum about 4-6 weeks after the operation. 4. Synaptic transmission at excitatory collateral synapses which remain after vagal degeneration is not altered by this hypersensitivity. 5. Neurones from ganglia which have been isolated and maintained in organ culture also become hypersensitive to applied ACh. this heightened chemosensitivity deveoops much faster in vitro; hypersensitivity in cultured ganglia becomes manifest within 4-5 days, in contrast with 4-6 weeks after vagus degeneration in vivo.

Acetylcholine↗
PubMedDate not supplied

The diagnostic accuracy of history, physical examination, and radiographs in the evaluation of traumatic knee disorders.

We prospectively looked at the diagnostic accuracy of clinical examination of the knee in patients with arthroscopically documented knee injuries. The study included 156 patients with 156 knee injuries (72 acute and 84 chronic) who were seen during 1 year at Martin Army Hospital at Fort Benning Georgia. All patients were given a primary diagnosis based on their history, physical examination, and routine radiographs. Fifty-seven patients were also given one or more secondary diagnoses. Magnetic resonance imaging scans and arthrograms were not used in the evaluation of these patients. The primary diagnosis was correct in 83% of the knees. Of 57 secondary diagnoses given, 54% were correct and 31% were incomplete. An incorrect diagnosis was made in 14% of knees for both primary and secondary diagnoses. There were four patients with no identifiable lesion other than synovitis. With the increasing cost of medical care, the need for expensive diagnostic studies such as magnetic resonance imaging needs to be evaluated. The cost of a magnetic resonance image scan ranges between $600 to $1200 depending on the institution. The use of magnetic resonance imaging as a routine diagnostic aid in the clinical examination of the knee is unnecessary. Arthroscopic surgery of the knee should be based on the patient's history, physical examination, and radiographs.

Adolescent↗
PubMed2002

Biologic characteristics of fibroblast cells cultured from the knee ligaments.

OBJECTIVE: To culture fibroblast cells from the knee ligaments and to study the biological characteristics of these cells. METHODS: Cells of the anterior cruciate ligament (ACL) and the medial collateral ligament (MCL) from New Zealand white rabbit were cultured in vitro. Cellular growth and expression of the collagen were analyzed. Moreover, an in vitro wound closure model was established and the healing of the ACL and the MCL cells was compared. RESULTS: Maximal growth for all these cells were obtained with Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, but RPMI 1640 and Ham's F12 media were not suitable to maintain these cells. Morphology of both ACL and MCL cells from New Zealand white rabbit was alike in vitro, but the MCL cells grew faster than the ACL cells. Both cell types produced similar amount of collagen in culture, but the ratio of collage type I to type III produced by ACL cells was higher than that produced by MCL cells. Wound closure assay showed that at 36 hours after injury, cell-free zones created in the ACL cultures were occupied partially by the ACL cells; in contrast, the wounded zone in the MCL cultures was almost completely covered by the cells. CONCLUSIONS: Although the ACL cells and the MCL cells from New Zealand white rabbit show similar appearance in morphology in culture, the cellular growth and the biochemical synthesis of collagen as well as the healing in vitro were significantly different. These differences in intrinsic properties of the two types of cells in vitro might contribute to the differential healing potentials of these ligaments in vivo.

Animals↗
PubMed1988

Factors that determine the occurrence of reperfusion arrhythmias.

The determinants of reperfusion arrhythmias were investigated in 63 open-chest dogs undergoing a 25-minute coronary artery occlusion followed by reperfusion. Heart rate correlated positively with the occurrence of reperfusion ventricular tachycardia (VT) and ventricular fibrillation (VF). Collateral flow during ischemia (radioactive microspheres) exhibited a strong negative correlation with the incidence of both VT and VF upon reperfusion. Importantly, a sensitive coupling was present, whereby small differences in flow were associated with large differences in rhythm disorders. The rise in intramyocardial CO2 tension (another index of severity of ischemia) was greater in dogs exhibiting reperfusion VT (p less than 0.001) and VF (p less than 0.08); however, this variable was significantly correlated with collateral flow (r = -0.57, p less than 0.01). The size of the occluded coronary bed, determined by postmortem perfusion, was not consistently related to VT; within a given range of occluded bed sizes, the incidence of VT was inversely related to collateral flow. Thus, reperfusion-induced VT is relatively independent of the size of the occluded bed, and is determined primarily by the degree of myocardial hypoperfusion. In contrast, VF did not develop with occluded beds less than 25% of the left ventricular mass; above this critical occluded bed size, its incidence was inversely related to collateral perfusion. Reperfusion VF is therefore determined by the association of a large occluded bed with a poor collateral flow. This study identifies and systematically analyzes three major determinants of reperfusion arrhythmias: (1) the severity of antecedent ischemia, estimated either from the degree of flow reduction or the rise in intramural CO2 tension; (2) the amount of ischemic/reperfused myocardium; and (3) the heart rate. In addition to conceptual interest and clinical implications, the findings have important implications for the design of future studies aimed at evaluating antiarrhythmic interventions in experimental models.

Animals↗
PubMed1989

Modeling splanchnic hemodynamics after distal splenorenal shunt: a computer simulation and sensitivity analysis.

The distal splenorenal shunt operation was specifically designed to preserve portal flow and maintain elevated portal pressure. However, although this goal is met in the immediate postoperative period, flow decreases over time, and in as many as 75% of alcoholic patients, portal flow is lost in the first year. Various explanations have been offered for this observation, and modifications of the original operation have been proposed (splenopancreatic disconnection). Although other portacaval shunts have been successfully modeled as electrical circuits, this approach has never been described for the distal splenorenal shunt. In this study we developed a computer program that modeled the distal splenorenal shunt as an electrical circuit. We performed an analysis to determine the sensitivity of portal flow to changes in each resistance element and then performed a series of simulation experiments to critically examine the various explanations offered for the gradual changes in hepatic hemodynamics. We found that portal flow was most sensitive to resistance in the renal vein followed by resistance in the anastomosis. The simulation experiments suggested a new alternative to splenopancreatic disconnection--restricting the ability of the splenic vein, anastomosis, or renal vein to dilate. Additional clinical studies will be needed to test these predictions.

Collateral Circulation↗
PubMed1993

Characterization of Ca2+ signals induced in hippocampal CA1 neurones by the synaptic activation of NMDA receptors.

1. A combination of confocal microscopy, whole-cell patch-clamp recording, intracellular dialysis and pharmacological techniques have been employed to study Ca2+ signalling in CA1 pyramidal neurones, within rat hippocampal slices. 2. In the soma of CA1 neurones, depolarizing steps applied through the patch-pipette resulted in transient increases in the fluorescence emitted by the Ca2+ indicator fluo-3. The intensity of the fluorescence transients was proportional to the magnitude of the Ca2+ currents recorded through the pipette. Both the somatic fluorescence transients and the voltage-activated Ca2+ currents ran down in parallel over a period of between approximately 15-45 min. The fluorescence transients were considered, therefore, to be caused by increases in cytosolic free Ca2+. 3. Under current-clamp conditions, high-frequency (tetanic) stimulation (100 Hz, 1 s) of the Schaffer collateral-commissural pathway led to compound excitatory postsynaptic potentials (EPSPs) and somatic Ca2+ transients. The somatic Ca2+ transients were sensitive to the N-methyl-D-aspartate (NMDA) receptor antagonist D-2-amino-5-phosphonopentanoate (AP5; 100 microM). These transients, but not the EPSPs, disappeared with a time course similar to that of the run-down of voltage-gated Ca2+ currents. Tetanus-induced somatic Ca2+ transients could not be elicited under voltage-clamp conditions. 4. Fluorescence images were obtained from the dendrites of CA1 pyramidal neurones starting at least 30 min after obtaining whole-cell access to the neurone. Measurements were obtained only after voltage-gated Ca2+ channel activity had run down completely. 5. Tetanic stimulation of the Schaffer collateral-commissural pathway resulted in compound EPSPs and excitatory postsynaptic currents (EPSCs), under current- and voltage-clamp, respectively. In both cases, these were invariably associated with dendritic Ca2+ transients. In cells voltage-clamped at -35 mV, the fluorescent signal increased on average 2-fold during the tetanus and decayed to baseline values with a half-time (t1/2) of approximately 5 s. 6. The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 10 microM) partially reduced the tetanus-induced EPSC without affecting the Ca2+ transients. In contrast, AP5, which also depressed the EPSC, substantially reduced or eliminated the Ca2+ transients. 7. In normal (i.e. 1 mM Mg(2+)-containing) medium, NMDA receptor-mediated synaptic currents displayed the typical region of negative slope conductance in the peak I-V relationship (between -90 and -35 mV). The dendritic tetanus-induced Ca2+ transients also displayed a similar anomalous voltage dependence, decreasing in size from -35 to -90 mV.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Ultrasonography in portal hypertension.

High resolution real time ultrasound is a non-invasive method of evaluating patients with suspected portal hypertension. The portosystemic collateral most frequently identified is the dilated coronary vein and its associated gastro-oesophageal varices. Other collaterals that can be seen include: gastrorenal, splenorenal, paraduodenal, periportal, pelvic and retroperitoneal varices along with a recanalized umbilical vein and ductus venosus. Using duplex doppler ultrasound, the rate and direction of portal blood flow can be ascertained. Sonography is better than barium studies in assessing whether gastro-oesophageal varices are present, however, it is not as sensitive as endoscopy, laparoscopy or portography.

Collateral Circulation↗
PubMed1998

MR imaging of knees having isolated and combined ligament injuries.

OBJECTIVE: Although clinical evaluation and MR imaging both accurately reveal injuries in knees with isolated ligament tears, physical examination becomes progressively less reliable when multiple lesions exist. We investigated the accuracy of MR imaging of knees having varying degrees and numbers of ligament injuries. SUBJECTS AND METHODS: We prospectively interpreted the MR images of 340 consecutive injured knees and compared these interpretations with the results of subsequent arthroscopy or open surgery, which served as the gold standard. Our interpretations of MR images focused on five soft-tissue supporting structures (the two cruciate ligaments, the two collateral ligaments, and the patellar tendon) and the two menisci. Patients were divided into three groups: no ligament injuries, single ligament injuries, and multiple ligament injuries. RESULTS: Using MR imaging, we found overall sensitivity and specificity for diagnosing ligament tears to be 94% and 99%, respectively, when no or one ligament was torn and 88% and 84%, respectively, when two or more supporting structures were torn. The difference in specificity was statistically significant (p < .0001). Sensitivity for diagnosing meniscal tears decreased as the number of injured structures increased, but the relationship achieved statistical significance (p = .001) only for the medial meniscus. For all categories of injury, MR imaging was more accurate than clinical evaluation, statistics for which were taken from the orthopedic literature. CONCLUSION: In knees with multiple ligament injuries, the diagnostic specificity of MR imaging for ligament tears decreases, as does the sensitivity for medial meniscal tears.

Adolescent↗
PubMed1987

Strain-selective effects of nicotine on electrophysiological responses evoked in hippocampus from DBA/2Ibg and C3H/2Ibg mice.

We used the hippocampal slice to examine extracellular electrophysiological responses to nicotine and the difference in sensitivity to nicotine-induced electrophysiological effects between the DBA and C3H mouse strains. Nicotine enhanced CA1 population spikes (PS) evoked by Schaffer collateral stimulation in a concentration-dependent manner (100 microM to 3.2 mM). This enhancement was slow to appear, achieving a maximum after 15 min. The enhanced PS was accompanied by the development of epileptiform activity (multiple PS's) at nicotine concentrations greater than or equal to 400 microM. Slices from DBA mice were significantly more sensitive than those from the C3H strain to these electrophysiological effects of nicotine. Mecamylamine (400 microM) blocked both the nicotine-induced PS enhancement and secondary population spikes in both strains, suggesting the involvement of nicotinic cholinergic receptors.

Animals↗
PubMed1992

Gamekeeper's thumb.

The term gamekeeper's thumb is widely used interchangeably with skier's thumb in reference to acute or chronic tears of the ulnar collateral ligament of the thumb MCP joint. The frequency of thumb injury in alpine skiing has not changed with recent changes in pole design. Release of the pole from the hand prior to impact with the ground will minimize injury. Arthrogram may be a useful adjunctive technique to identify the presence of a Stener lesion and strengthen the indications for surgery in borderline cases. The sensitivity and specificity of this test have not been established. Current trends favor acute surgical repair for complete tears of the ulnar collateral ligament of the thumb MCP joint as documented by clinical examination with stress radiography. Good results are obtainable with late reconstruction, and comparable results have been noted with the most commonly used techniques.

Humans↗
PubMed1985

On the role of substance P and serotonin in the pyloric motor control. An experimental study in cat and rat.

Vagal nerve stimulation caused a release of substance P (SP) and serotonin (5-HT) into the feline portal circulation. Both substances are gut spasmogens and were demonstrated in gut nerves by immunocytochemistry. In anesthetized cats gastric and pyloric motility were studied simultaneously at stimulation with SP or 5-HT via the splenic artery or at stimulation of the extrinsic nerves to evaluate their role in the motor control of these regions. The vagally induced pyloric contraction was noncholinergic and nonadrenergic but sensitive to hexamethonium in contrast to the cholinergic gastric contraction, which was resistant to ganglionic blockade. Splanchnic nerve stimulation caused relaxatory gastropyloric responses; the gastric relaxation was sensitive to adrenergic or ganglionic blockade in contrast to the pyloric relaxation. Infrequent contractile responses were seen, which were antagonized by atropine. Injection of SP via the splenic artery elicited contractile gastropyloric responses, which were sensitive to atropine and an antagonistic SP-analogue (SPA) but resistant to hexamethonium, indicating SP activating a final cholinergic neuron. The vagally induced pyloric contraction was resistant to atropine but sensitive to SPA and hexamethonium, indicating involvement of SP in the activation of preganglionic neurons as well. Involvement of SP in a vagal afferent mechanism is possible, since heat activation of the distal end of the divided vagal nerve induced a gastric contraction, sensitive to atropine and SPA but not to ganglionic blockade, indicating antidromic activation of SP afferents which via axon collaterals excite cholinergic neurons. A regional difference between stomach and pylorus was suggested by the different motor responses after pharmacological blockade, heat-activation or i.a. injection of capsaicin. The contractile pyloric responses to 5-HT were antagonized by peripheral blockade of 5-HT2 receptors. However, such blockade did not influence the motor responses to extrinsic nerve stimulation, suggesting that 5-HT is not essential for the mediation of these responses. The contractile responses to SP or 5-HT were studied in vitro in antral and pyloric strips from the rat. These responses were antagonized by SPA or SP tachyphylaxis and peripheral blockade of 5-HT2 receptors respectively. The responses were not reduced by tetrodotoxin, indicating main activation of muscular receptors. However, the contractile responses were reduced by atropine or hexamethonium, except the SP-induced pyloric contraction, which was atropine-sensitive but hexamethonium-resistant.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

CT diagnosis of splenic vein occlusion: imaging features, etiology and clinical manifestations.

BACKGROUND: Previous reports have described the computed tomographic (CT) appearance of collateral veins following splenic vein occlusion (SVO). This retrospective study was performed to determine the etiology, clinical manifestations, and accuracy of CT diagnosis in patients with this entity. METHODS: A computer search of radiology reports for a 1-year period found 52 patients with SVO diagnosed by absence of visualization of the splenic vein accompanied by the formation of the expected perigastric collateral veins. Clinical data were reviewed for sequela of SVO and clinical impact of the diagnosis. RESULTS: In 12 cases, other studies confirmed the CT diagnosis of SVO. In no case was the CT diagnosis proved to be incorrect by other imaging studies. Angiographic records found five additional cases with SVO not diagnosed by CT, but two of five had convincing CT evidence of SVO noted upon reevaluation by the authors. Review of clinical data showed heme-positive stool in six, of which three had significant gastrointestinal hemorrhage. Splenic infarction occurred in two cases. CONCLUSIONS: Our data indicate that SVO is more common than previously suspected and usually remains clinically silent, but CT appears to be highly specific and fairly sensitive for its diagnosis.

Collateral Circulation↗
PubMedDate not supplied

Hemodynamic effect of cerebral vasospasm in humans: a modeling study.

A mathematical model of cerebral hemodynamics during vasospasm is presented. The model divides arterial hemodynamics into two cerebral territories: with and without spasm. It also includes collateral circulation between the two territories, cerebral venous hemodynamics, cerebrospinal fluid circulation, intracranial pressure (ICP) and the craniospinal storage capacity. Moreover, the pial artery circulation in both territories is affected by cerebral blood flow (CBF) autoregulation mechanisms. In this work, a numerical value to model parameters was given assuming that vasospasm affects only a single middle cerebral artery (MCA). In a first stage, the model is used to simulate some clinical results reported in the literature, concerning the patterns of MCA velocity, CBF and pressure losses during vasospasm. The agreement with clinical data turns out fairly good. In a second stage, a sensitivity analysis on some model parameters is performed (severity of caliber reduction, longitudinal extension of the spasm, autoregulation gain, ICP, resistance of the collateral circulation, and mean systemic arterial pressure) to clarify their influence on hemodynamics in the spastic territory. The results suggest that the clinical impact of vasospasm depends on several concomitant factors, which should be simultaneously taken into account to reach a proper diagnosis. In particular, while a negative correlation between MCA velocity and cross sectional area can be found until CBF is well preserved, a positive correlation may occur when CBF starts to decrease significantly. This might induce false-negative results if vasospasm is assessed merely through velocity measurements performed by the transcranial Doppler technique.

Blood Flow Velocity↗
PubMed2003

Ultrastructural examination of the somatic innervation of ventrotubercular cells in the rat.

Ventrotubercular cells are multipolar cells in the ventral cochlear nucleus (VCN) that project a collateral axon to the ipsilateral dorsal cochlear nucleus (DCN). These cells are thought to be involved in sensitizing DCN output neurons to spectral shapes that represent the location of a sound source in space. The present report focused on the neuronal composition of this pathway. Intracellular labeling studies in cats and mice have described two types of ventrotubercular cells (Smith and Rhode [1989] J Comp Neurol. 282:595-626; Oertel et al. [1990] J Comp Neurol. 295:136-154). In cats, one difference between the two classes is that type I multipolar neurons have fewer than 35% of their somata apposed by terminals, whereas type II cells have greater than 70% apposition values. Intracellular recordings from single cells, however, are difficult and thus limit the yield of data. We investigated whether a two-component description of the ventrotubercular pathway was representative of a larger population. This issue was addressed by retrogradely labeling ventrotubercular neurons with an extracellular injection of biotinylated dextran amine into the DCN of rats. These injections labeled many VCN neurons, thus providing a more complete view of the pathway than previous studies. Thirty-eight labeled cells were selected for electron microscopic analysis with respect to their location, cell body size, and ultrastructural morphology. We observed labeled type I and type II neurons, but unlike ventrotubercular cells in cats, many of these neurons in rats (17 of 38 cells) had appositions between 35% and 70%. On the basis of this analysis, a third class of ventrotubercular cell, called the adendritic neuron, was revealed. Adendritic neurons have small somata with many filopodial appendages, no observable dendrites, and high percentage of terminal appositions (>80%). The results demonstrated that the ventrotubercular pathway in the rat is diverse.

Animals↗
PubMed2002

Renal angiography in children with polyarteritis nodosa.

This study describes the angiographic findings in children with polyarteritis nodosa (PAN). Visceral angiograms of 25 children with PAN were reviewed retrospectively by two independent radiologists. In the PAN group, 40% of children had aneurysms demonstrated on selective renal angiography. Most aneurysms affected small and medium-sized arteries. There was agreement between radiologists regarding medium and large aneurysms ( K=0.81), but less so for smaller aneurysms. Overall, the presence of medium or large aneurysms was significantly associated with the presence of renal impairment and hypertension. Non-aneurysmal changes were detected more commonly on renal angiography than aneurysms in the PAN group. The most reliable non-aneurysmal signs were perfusion defects, the presence of collateral arteries, lack of crossing of peripheral renal arteries, and delayed emptying of small renal arteries. The sensitivity and specificity of renal angiographic diagnosis of PAN using aneurysms alone was 43% (SE 10%) and 69% (SE 14%) respectively. The sensitivity increased to 80%, and specificity fell to 50% for angiogram positivity defined as the presence of at least one of the most reliable non-aneurysmal signs irrespective of the presence of aneurysms. Aneurysms were also demonstrated on hepatic and mesenteric angiography, and non-aneurysmal signs were found on hepatic, mesenteric, and splenic angiography, although interobserver agreement for angiographic findings in these vascular beds was lower. It is important to consider both aneurysmal and non-aneurysmal angiographic signs, and to include examinations of several vascular beds when utilising angiography for diagnostic purposes in children with PAN.

Adolescent↗
PubMed2005

Chronic administration of dehydroepiandrosterone sulfate (DHEAS) primes for facilitated induction of long-term potentiation via sigma 1 (sigma1) receptor: optical imaging study in rat hippocampal slices.

Dehydroepiandrosterone sulfate (DHEAS), one of the most abundant neurosteroids synthesized de novo in the nervous system, has well characterized effects on memory and cognitive performances. However, little is known about the underlying synaptic mechanisms. In this study, we investigated the effects of chronic administration of DHEAS (20 mg/kg for 7 days) on the plasticity of Schaffer collateral-CA1 synapses by applying an optical recording technique on the hippocampal slices stained with voltage-sensitive dyes. We report here that chronically administered DHEAS significantly facilitated the induction of frequency-dependent LTP, termed DHEAS-facilitated LTP. While tetanus of at least 50 pulses (at 100 Hz) were required to induce LTP in control rats, only 20 pulses were needed in DHEAS-treated animals. In contrast DHEA, the non-sulfated form of DHEAS, had no facilitating effect on the induction of LTP. We found that chronically administered DHEAS did not alter the presynaptic glutamate release in response to both single pulse and tetanic stimulation, suggesting that certain alterations happened in postsynaptic neurons. Co-administration of the sigma 1 (sigma1) receptor antagonists, haloperidol or NE100, with DHEAS completely inhibited the DHEAS-facilitated LTP. However, acute administration of sigma1 receptor antagonists to the slices did not affect the induction of DHEAS-facilitated LTP, suggesting that sigma1 receptor is a key target of chronic actions of DHEAS but is not involved in the induction of DHEAS-facilitated LTP. Our findings provide evidence that chronically administered DHEAS plays a priming role in inducing a facilitated synaptic plasticity probably via a chronic activation of sigma1 receptor in rat hippocampal CA1 pyramidal cells.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMedDate not supplied

Two-dimensional time-of-flight MR venography: assessment with detection of chronic deep venous thrombosis in combination with magnetization transfer contrast.

PURPOSE: The purpose of this study was to determine the optimum imaging parameters for 2D-TOF MR venography (MRV) of the pelvis and suprapopliteal deep venous system in combination with off-resonance magnetization transfer constant (MTC) and to evaluate the use of MRV in patients suspected of having chronic deep venous thrombosis (DVT) by comparing its accuracy with that of conventional venography (CV). METHOD: MRV was performed in 10 normal subjects to determine the optimum imaging parameters. Systematically varied scan parameters included flip angles ranging from 30 to 120 degrees by 10 degrees increments. Best TR was calculated by using the theoretical relation between the optimal TR and flow velocity. We then evaluated the use of MRV in 26 patients (total 52 deep venous systems) suspected of having chronic DVT by comparing its accuracy in evaluating the intrapelvic and suprapopliteal deep venous system with that of CV. RESULTS: The optimal imaging parameters for intrapelvic and suprapopliteal venous system MRV were found to be a flip angle of 60 degrees and a pulse sequence of 35/6.9 (TR ms/TE ms) combined with an off-resonance MTC technique. All the main veins of the intrapelvic and suprapopliteal venous systems were clearly demonstrated in each subject. The sensitivity of MRV was 100% and its specificity was 100% for diagnosis of pelvic venous stenosis. The collateral vessels were demonstrated with MRV in all patients. CONCLUSION: 2D-TOF off-resonance MTC MRV of the pelvis and the suprapopliteal lower extremities is suitable for evaluation of intrapelvic branches and suprapopliteal deep venous system and chronic DVT.

Chronic Disease↗
PubMed1992

Activation of protein kinase C suppresses responses to NMDA in rat CA1 hippocampal neurones.

1. The effects of 1-oleoyl-2-acetylglycerol (OAG), an activator of protein kinase C (PKC), on NMDA receptor-mediated responses were investigated in CA1 neurones of hippocampal slices using current- and voltage-clamp techniques. 2. Topical application of OAG caused a suppression of the slow, voltage-sensitive, NMDA receptor-mediated component of excitatory postsynaptic potentials (EPSPs) evoked by stimulating the schaffer-collateral commissural afferents and had no effect on the fast, voltage-insensitive, quisqualate/kainate component. 3. OAG suppressed the amplitude of inward current responses to NMDA down to about one-third of control responses. OAG could also increase the duration of the responses to NMDA by up to twofold. The effect of OAG on the duration but not on the amplitude of the response to NMDA was blocked by pre-loading cells with the K+ channel blocker, Cs+. Topical application of OAG had no significant effect on current responses to quisqualate. 4. An OAG isomer, which does not activate PKC, had no effect on responses to NMDA. Intracellular application of the kinase inhibitor, H-7, completely blocked the effect of OAG on the amplitude and duration of responses to NMDA, as well as on the slow EPSP. Finally, topical application of another activator of PKC, phorbol 12-myristate 13-acetate (PMA), also suppressed responses to NMDA. PMA reduced the slow component of synaptic responses in about half of the cells tested. 5. We propose that activation of PKC in CA1 hippocampal neurones suppresses NMDA receptor-mediated responses.

Action Potentials↗