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A Lie

Publications and source records attributed to A Lie.

At least 19 recordsLinked to original sources
PubMed2001

Functional and molecular analysis of transient voltage-dependent K+ currents in rat hippocampal granule cells.

1. We have investigated voltage-dependent outward K+ currents of dentate granule cells (DGCs) in acute brain slices from young and adult rats using nucleated and outside-out patch recordings. 2. In adult DGCs, the outward current pattern was dominated by a transient K+ current component. One portion of this current (approximately 60%) was blocked by micromolar concentrations of tetraethylammonium (TEA; IC50 42 microM) and BDS-I, a specific blocker of Kv3.4 subunits (2.5 microM). A second component was insensitive to tetraethylammonium (10 mM) and BDS-I. The transient outward current could be completely blocked by 4-aminopyridine (IC50 296 microM). 3. The TEA- and BDS-I-sensitive and the TEA-resistant current components were isolated pharmacologically. The current component that was blocked by BDS-I and TEA showed a depolarized threshold of activation (approximately -30 mV) reminiscent of Kv3.4 subunits, while the current component resistant to TEA activated at more hyperpolarized potentials (approximately -60 mV). 4. In nucleated patches obtained by placing the patch pipette adjacent to the apical dendrite, only small Na+ currents and small BDS-I-sensitive transient currents were detected. Nucleated patches obtained from either the cell soma (see above) or the axon hillock showed significantly larger amplitude Na+ currents as well as larger BDS-I-sensitive currents, indicating that this current was predominantly localized within the axosomatic compartment. This result was in good agreement with the distribution of Kv3.4 protein as determined by immunohistochemistry. 5. Current-clamp as well as mock action potential-clamp experiments revealed that the BDS-sensitive current component contributes to action potential repolarization. 6. A comparison of the two age groups (4-10 days and 60-100 days) revealed a marked developmental up-regulation of the BDS-I-sensitive component. These functional changes are paralleled by a developmental increase in Kv3.4 mRNA expression determined by quantitative real-time RT-PCR, as well as a pronounced up-regulation of Kv3.4 on the protein level determined by immunohistochemistry. 7. These functional and molecular results argue that Kv3.4 channels located predominantly in the axosomatic compartment underlie a transient K+ current in adult DGCs, and that these channels are functionally important for regulating spike repolarization. The marked developmental regulation suggests an important role of Kv3.4 in neuronal maturation.

Animals↗
PubMed2000

Synaptic plasticity in the human dentate gyrus.

Activity-dependent plasticity is a fundamental feature of most CNS synapses and is thought to be a synaptic correlate of memory in rodents. In humans, NMDA receptors have been linked to verbal memory processes, but it is unclear whether NMDA receptor-dependent synaptic plasticity can be recruited for information storage in the human CNS. Here we have for the first time analyzed different forms of synaptic plasticity in human hippocampus. In human subjects who show a morphologically intact hippocampus that is not the primary seizure focus, NMDA receptor-dependent long-term potentiation (LTP) and forskolin-induced long-lasting potentiation are readily induced at the perforant path-dentate gyrus synapse. In this group, long-term potentiation could be partially depotentiated by low-frequency stimulation. Because patients with a hippocampal seizure focus showed a marked reduction in verbal memory performance in previous studies, we asked whether synaptic plasticity is similarly affected by the presence of a hippocampal primary seizure focus. We found that the amount of potentiation induced by high-frequency stimulation or perfusion of forskolin is dramatically reduced in this patient group. In addition, low-frequency stimulation is not effective in inducing synaptic depression. In summary, we show that activity-dependent synaptic plasticity with properties similar to the rodent is available for information storage in the human hippocampus. Because both verbal memory processes and synaptic plasticity are impaired by a hippocampal seizure focus, we suggest that impaired synaptic plasticity may contribute to deficient declarative memory in human temporal lobe epilepsy.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Microisolated mouse osteoclasts express VIP-1 and PACAP receptors.

Skeletal tissue contains a network of nerve fibers expressing several neuropeptides, including vasoactive intestinal peptide (VIP) and the related peptide pituitary adenylate cyclase activating peptide (PACAP). These peptides have been demonstrated to regulate osteoclast formation and osteoclast activity. Using atomic force microscopy and by analysing changes of the intracellular calcium concentrations, we have recently demonstrated that multinucleated rat osteoclasts have cell membrane binding sites recognising VIP and PACAP. In the present study, we have further studied the expression of VIP receptor subtypes in mouse bone marrow cultures and isolated osteoclasts. A micromanipulation technique was used to isolate pure populations of osteoclasts formed in PTH-stimulated mouse bone marrow cultures. By reverse transcriptase polymerase chain reaction (RT-PCR), we studied the expression of mRNA for VIP-1, VIP-2, and PACAP receptors. The purity of the microisolated osteoclasts was determined by studying the expression of specific mRNA associated with the phenotypic trait of osteoclasts or osteoblasts/stromal cells. In this study, we show that mouse osteoclasts express VIP-1 and PACAP, but not VIP-2, receptor mRNA.

Acid Phosphatase↗
PubMed2000

Vasoactive intestinal peptide regulates osteoclast activity via specific binding sites on both osteoclasts and osteoblasts.

Clinical and experimental observations, together with immunohistochemical findings, suggest that neuro-osteogenic interactions may occur in the skeleton. In this study, we have examined the effect of vasoactive intestinal peptide (VIP), one of the neuropeptides present in bone, on the activity of the bone-resorbing osteoclast. Effects on bone resorption were assessed by counting the number of pits formed by rat osteoclasts incubated on devitalized slices of bovine cortical bone. Under conditions with an initially sparse density of stromal cells/osteoblasts, VIP caused a rapid cytoplasmic contraction and decreased motility of osteoclasts. This was coupled with a decrease in the number of resorption lacunae and a decrease in the total area resorbed by the osteoclasts in 48-h cultures. Time-course experiments revealed that the inhibitory effects on contraction and motility were transient and that the cells gradually regained their activity, such that, when culture time was prolonged to 120 h, a stimulatory effect by VIP on bone resorption was observed. When osteoclasts were incubated on bone slices, in the presence of an initially large number of stromal cells/osteoblasts, VIP treatment increased the number of resorption pits and total bone area resorbed in 48-h cultures. Using atomic force microscopy, we provide direct evidence that both osteoclasts and stromal cells/osteoblasts bind VIP. Also, VIP was shown to cause a rapid rise of intracellular calcium in osteoclasts and in a proportion (20%) of stromal cells/osteoblasts. Taken together, these data suggest that differentiated osteoclasts are equipped with receptors for VIP that are linked to a transient inhibition of osteoclast activity and, in addition, that stromal cells/osteoblasts have VIP receptors coupled to a delayed stimulation of osteoclastic resorption.

Animals↗
PubMed2000

Prevalence of hepatitis A, B, C, and E antibody in flying airline personnel.

OBJECTIVES: The aim of the study was to detect the prevalence of antibodies against hepatitis A, B, C, and E viruses in flying airline personnel, and to determine the necessity of hepatitis A vaccination to prevent such infections related to occupational exposure. METHODS: Antibodies against hepatitis A (HAV), B (HBV), C (HVC), and E (HEV) were tested for using standard enzyme immunoassay in airline personnel, 208 flying personnel, 199 ground crew, and 204 employees from companies not involved in travel activities. RESULTS: Prevalence of antibodies against HAV was less than 5% in each group, and there was no significant difference between the three groups. Prevalence of antibodies against HEV was significantly higher in flying personnel (3.4%) than in the control groups. Prevalence of antibodies against HBV and HCV was low in each of the three groups and there were no differences between the three groups. CONCLUSIONS: Infection with HAV, HBV and HCV does not seem to represent an occupational hazard to flying personnel. It is possible that flying personnel are exposed to infection with HEV, however, presently no vaccine is available.

Adult↗
PubMed1999

Loss of dynorphin-mediated inhibition of voltage-dependent Ca2+ currents in hippocampal granule cells isolated from epilepsy patients is associated with mossy fiber sprouting.

The endogenous kappa receptor selective opioid peptide dynorphin has been shown to inhibit glutamate receptor-mediated neurotransmission and voltage-dependent Ca2+ channels. It is thought that dynorphin can be released from hippocampal dentate granule cells in an activity-dependent manner. Since actions of dynorphin may be important in limiting excitability in human epilepsy, we have investigated its effects on voltage-dependent Ca2+ channels in dentate granule cells isolated from hippocampi removed during epilepsy surgery. One group of patients showed classical Ammon's horn sclerosis characterized by segmental neuronal cell loss and astrogliosis. Prominent dynorphin-immunoreactive axon terminals were present in the inner molecular layer of the dentate gyrus, indicating pronounced recurrent mossy fiber sprouting. A second group displayed lesions in the temporal lobe that did not involve the hippocampus proper. All except one of these specimens showed a normal pattern of dynorphin immunoreactivity confined to dentate granule cell somata and their mossy fiber terminals in the hilus and CA3 region. In patients without mossy fiber sprouting the application of the kappa receptor selective opioid agonist dynorphin A ([D-Arg6]1-13, 1 microM) caused a reversible and dose-dependent depression of voltage-dependent Ca2+ channels in most granule cells. These effects could be antagonized by the non-selective opioid antagonist naloxone (1 microM). In contrast, significantly less dentate granule cells displayed inhibition of Ca2+ channels by dynorphin A in patients with mossy fiber sprouting (Chi-square test, P < 0.0005). The lack of dynorphin A effects in patients showing mossy fiber sprouting compares well to the loss of kappa receptors on granule cells in Ammon's horn sclerosis but not lesion-associated epilepsy. Our data suggest that a protective mechanism exerted by dynorphin release and activation of kappa receptors may be lost in hippocampi with recurrent mossy fiber sprouting.

Adolescent↗
PubMed1999

Cholera toxin and forskolin stimulate formation of osteoclast-like cells in mouse marrow cultures and cultured mouse calvarial bones.

Osteoclasts are hematopoietic in origin and formed by proliferation, differentiation and fusion of osteoclast progenitor cells. However, the signal transducing mechanisms involved in generation of osteoclasts are not clear. We have used two well-known adenylate cyclase stimulators to examine the effect of cyclic AMP (cAMP) on the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in cultured mouse calvarial bones and in mouse bone marrow cultures. The effects of forskolin and cholera toxin were compared with those of parathyroid hormone (PTH) and 1,25(OH)2vitaminD3 (1,25(OH)2D3). PTH, as well as forskolin and cholera toxin, increased the number of osteoclast profiles/mm bone in 24-h and 120-h cultures of mouse calvarial bones. In mouse bone marrow cultures, 1,25(OH)2D3 or PTH stimulated formation of TRAP-positive multinucleated cells. Moreover, forskolin or cholera toxin produced dose-dependent stimulation of these cells at a range of concentrations correlating with their effect on cAMP production. The osteoclastic phenotype of the TRAP-positive cells was demonstrated by autoradiography of 125I-labelled calcitonin binding and by the bone-resorbing activity of the cells. The sustained presence (0-9 d) of forskolin or PTH was required to obtain maximal formation of osteoclasts. However, the presence of 1,25(OH)2D3 was required only for the last 3 d of culture for maximal osteoclast formation. We conclude that PTH may stimulate osteoclast generation using the adenylate cyclase cAMP system as a signal transduction mechanism.

Acid Phosphatase↗
PubMed1998

[Occupational diseases in an airline company].

617 cases of occupational health disorders in an average population of approximately 4,400 were reported by the Occupational Health Services of the Norwegian section of SAS during the period 1985 to 1996. Musculoskeletal disorders accounted for approximately 75% of all registered disorders. Wherever possible, occupational disorders should be registered and preventive measures initiated by the company. It is therefore of great importance that a registration system should include all occupational disorders. If we compare our figures with the official Norwegian figures from the Labour Inspectorate, we may conclude that only 3-4% of occupational disorders are reported to the Authorities. In particular it seems that many disorders which do not yield economic compensation (musculoskeletal disorders, and mental stress and burnout syndromes) are not reported at all, making it less likely that preventive measures are implemented. The Nordic figures indicate that inadequate reporting occurs more frequently in Norway than in Sweden, Denmark and Finland.

Aerospace Medicine↗
PubMed1996

'Superwarfarin' poisoning leading to prolonged coagulopathy.

An elderly Chinese was admitted for haemetemesis. Investigations revealed markedly prolonged clotting times that recurred every few days despite administration of fresh frozen plasma and vitamin K. The derangement in coagulation lasted more than 3 months. In view of the absence of liver disease or malabsorption syndromes, long-acting anticoagulant ('superwarfarin') ingestion was suspected. The diagnosis of rodenticide poisoning was hampered by the lack of available assays. Diagnosis of brodifacoum intoxication using HPLC was confirmed only months after prolonged treatment with high dose vitamin K1. Superwarfarin poisoning should be suspected in cases of deranged coagulation refractory to treatment since these over-the-counter rodenticides are easily available.

4-Hydroxycoumarins↗
PubMed1995

Crash pulse recorder--validation in full scale crash tests.

Estimation of the accident severity is a fundamental requirement in accident reconstruction and analysis. Accident severity can be measured in many different ways, but in frontal collisions change of velocity, energy equivalent speed or equivalent barrier speed are frequently used parameters. These parameters are most often estimated from vehicle deformation. It is known, however, that the quality of these estimates is limited if compared with these obtained in laboratory test conditions. To be able to achieve almost the same measurements and measurement accuracy in real-life accidents as in the laboratory, where the acceleration time history is measured, an on-board measurement technique is required. This presentation gives results of tests of a low cost device for measuring the crash pulse for a car involved in an accident, concerning systematic and random error. The device, called the Crash Pulse Recorder (CPR), has been tested previously in several sled tests. The CPR is based on measurement of the movement of the mass in a spring mass system in a collision. A brief description of its construction is also included. The CPR is an integral part of a large accident data collection system including interior and exterior deformation measurements and evaluation of injury outcome. This report presents the results of several full-scale crash tests, undertaken to evaluate the accuracy and precision of the CPR in cars in different impact modes. The tests comprised both offset and angled collisions. Most of the tests were car to car collisions, but barrier tests were also performed. The random error of the CPR was found to be 2.2 km/hr for the delta V measurements and 0.6 g for mean acceleration.

Acceleration↗
PubMed1995

Accuracy of implant-supported prostheses in the edentulous jaw: analysis of precision of fit between cast gold-alloy frameworks and master casts by means of a three-dimensional photogrammetric technique.

Distortions of 15 routine implant-supported prostheses were measured in relation to the master casts after completion by means of a 3-dimensional (3-D) photogrammetric technique. All prostheses were designed as one-piece gold-alloy castings with resin teeth. Five of the prostheses were placed in the edentulous maxilla, and the remaining were placed in the lower jaw. Distortion of the cylinders was mostly observed in the horizontal plane (x- and y-axis) while the vertical aspect seemed to be more stable. The mean 3-D center point distortion was 42 (SD 15) and 74 (SD 38) microns for the upper and lower jaws, respectively. The measurements revealed a range of 3-D center point distortion from 16 to 80 and 15 to 165 microns for the different jaws, respectively. The corresponding 3-D mean angular distortion of the cylinders was 51 (SD 35) microns in lower and 70 (SD 75) microns in the upper jaws. A correlation was found between 3-D center point distortion and the width as well as the curvature of the implant arch, indicating more displacement the wider and the more curved the arch was. The 3-D center point distortion was also significantly higher in the upper jaws which could possibly be explained by the curvature of the implant arch and higher numbers of implants in the upper jaws. Further problems with the fit of upper jaw castings could be related to more alloy in the castings and poor alignment of implants.

Dental Prosthesis Design↗
PubMed1995

Intensive consolidation chemotherapy for newly diagnosed acute myeloid leukemia using a regime containing moderate dose cytosine arabinoside and mitoxantrone.

Fifty patients with previously untreated acute myeloid leukemia were treated with an induction regimen consisting of cytosine arabinoside 100 mg/m2 per day by 18 h i.v. infusion for 7 days, daunorubicin 50 mg/m2 per day by i.v. bolus injection for 3 days and etoposide 75 mg/m2 per day by 1 h i.v. infusion for 7 days. Thirty seven of them (74%) went into complete remission (CR) and they all then received two consecutive courses of consolidation chemotherapy consisting of cytosine arabinoside 500 mg/m2 per day by 1 h i.v. infusion every 12 h for 4 days (total eight doses) and mitoxantrone 12 mg/m2 daily by 30 min i.v. infusion for 3 days. They were followed by maintenance chemotherapy with cytosine arabinoside and thioguanine 2 monthly. With a median follow up time of 24 months, 20 of the 37 complete responders had relapsed (54%). The disease-free survival (DFS) of 37 CR patients and the overall survival of all patients at 24 months were 37 and 44%, respectively. Age of patients and number of courses of induction chemotherapy to achieve CR were significant factors predicting DFS. Myelosuppression was the major toxic side effects. Ten patients had prolonged marrow suppression following consolidation chemotherapy. In conclusion, despite the significant myelosuppression observed, overall improvement in treatment outcome was not demonstrable with the use of this intensive consolidation therapy.

Adolescent↗
PubMed1995

Treatment outcome and prognostic factors for primary nasal lymphoma.

PURPOSE: To report our experience managing a large series of Chinese patients with primary nasal lymphoma. PATIENTS AND METHODS: From January 1975 to December 1993, 100 patients (median age, 50 years) with newly diagnosed primary nasal lymphoma were studied. There were four low-grade, 62 intermediate-grade, nine high-grade, and 25 unclassifiable lymphomas. Immunophenotyping was performed in 45 patients: eight B cell, 35 T cell, and two uncertain. All cases of angiocentric lymphoma that were typed were T cell. Fifty-two patients had stage I disease, 15 had stage II, four had stage III, and 29 had stage IV. Only 15 patients had B symptoms (weight loss, night sweats, and/or fever), and 11 had bulky disease. Thirty-nine patients with clinically localized stage I and II disease received local radiotherapy alone (before 1980), and the remaining 28 stage I and II patients received combination chemotherapy followed by local radiotherapy. The 33 patients with advanced stage III and IV disease were given combination chemotherapy, and additional radiotherapy was given to five of them who had bulky local disease. RESULTS: Significantly higher complete remission rates were observed in patients with early stages of disease and those without B symptoms. Superior disease-free survival after complete remission was observed in patients with stage I/II disease. Univariate factors associated with a better overall survival included age less than 60 years, stage I disease, and absence of B symptoms. Survival was significantly better in the subgroup of patients with stage I disease. CONCLUSION: Patients with nasal lymphoma, especially those with advanced disease, seemed to have a poor prognosis, and their clinical outcome was not improved significantly by the use of chemotherapy instead of radiotherapy or the use of doxorubicin-containing chemotherapeutic regimens.

Adolescent↗
PubMed1994

Photogrammetry for documentation of vehicle deformations--a tool in a system for advanced accident data collection.

Vehicle deformations are important sources for information about the performance of safety systems. Photogrammetry has developed vastly under recent years. In this study modern photogrammetrical methods have been used for vehicle deformation analysis. The study describes the equipment for documentation and recording in the field (semi-metric camera), and a system for photogrammetrical measurements of the images in laboratory environment (personal computer and digitizing tablet). The material used is approximately 500 collected and measured cases. The study shows that the reliability is high and that accuracies around 15mm can be achieved even if the equipment and routines used are relatively simple. The effects of further development using video cameras for data capture and digital images for measurements are discussed.

Accidents, Traffic↗
PubMed1994

Photogrammetric measurements of implant positions. Description of a technique to determine the fit between implants and superstructures.

A photogrammetric technique was designed to measure the position of dental implants in 3 dimensions to enable assessment of the fit of superstructures placed on the implants. A relatively simple camera set-up was developed and tested. Calibration of the camera was performed in a high-precision analytical plotter and revealed a film measurement accuracy of 0.005 mm. The achieved measuring accuracy for clear and well defined points on clinical components was found to be around 0.02 mm. To find the center points of the implants, points on the circumference were measured. These points are not well defined, which resulted in an estimation of the center point of the implant with a precision of 0.05 mm. Independent measurements of a prosthesis with 5 implants were also within the precision of 0.05 mm. The angular orientation of the top surface of the implant cylinder (abutment, brass replica of gold alloy cylinder of the framework) was measured with a precision of 0.01 radians, which corresponded to an error with a peripheral gap of about 0.03 mm. This value was about 5-10 times lower than the clinical fit between frameworks and abutments, measured in 3 randomly selected clinical cases.

Dental Implants↗
PubMed1994

Mucosal topography around implants in edentulous upper jaws. Photogrammetric three-dimensional measurements of the effect of replacement of a removable prosthesis with a fixed prosthesis.

A photogrammetric technique was tested to measure the topography of the mucosa around implants, placed in edentulous upper jaws. Photographs were taken of casts from 6 patients, who all had used a removable overdenture for one year. Another series of photographs was taken on new casts after the use of a fixed prosthesis for a second year. The 6 pairs of photographs were measured and compared in an analytical stereo plotter for surface contour and implant positions. The results from the measurements indicated a trend of general recession of the mucosa after one year with fixed prosthesis, both on the buccal as well as on the palatal side. The mean volume of recession was 222.4 mm3, corresponding to an average of 0.4 mm3/mm2 of mucosa. More recession was generally observed on the palatal side, but obvious variations between the patients were present. In conclusion, the photogrammetric technique was considered to be well suited for analysing tissue contours in various dental situations.

Aged↗