| 1. |
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| 2. |
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| 3. |
- Diczfalusy, Elin, et al.
(författare)
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A model for simulation and patient-specific visualization of the tissue volume of influence during brain microdialysis
- 2011
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Ingår i: Medical and Biological Engineering and Computing. - : Springer Publishing Company. - 0140-0118 .- 1741-0444. ; 49:12, s. 1459-1469
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Tidskriftsartikel (refereegranskat)abstract
- Microdialysis can be used in parallel to deep brain stimulation (DBS) to relate biochemical changes to the clinical outcome. The aim of the study was to use the finite element method to predict the tissue volume of influence (TVI(max)) and its cross-sectional radius (r (TVImax)) when using brain microdialysis, and visualize the TVI(max) in relation to patient anatomy. An equation based on Fick's law was used to simulate the TVI(max). Factorial design and regression analysis were used to investigate the impact of the diffusion coefficient, tortuosity and loss rate on the r (TVImax). A calf brain tissue experiment was performed to further evaluate these parameters. The model was implemented with pre-(MRI) and post-(CT) operative patient images for simulation of the TVI(max) for four patients undergoing microdialysis in parallel to DBS. Using physiologically relevant parameter values, the r (TVImax) for analytes with a diffusion coefficient D = 7.5 × 10(-6) cm(2)/s was estimated to 0.85 ± 0.25 mm. The simulations showed agreement with experimental data. Due to an implanted gold thread, the catheter positions were visible in the post-operative images. The TVI(max) was visualized for each catheter. The biochemical changes could thereby be related to their anatomical origin, facilitating interpretation of results.
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| 4. |
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| 5. |
- Diczfalusy, Elin, et al.
(författare)
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Simulations and visualizations for interpretation of brain microdialysis data during deep brain stimulation
- 2012
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Ingår i: IEEE Engineering in Medicine and Biology Society (EMBC), 2012. - : IEEE. - 9781424441198 - 9781424441204 - 9781457717871 ; , s. 6438-6441
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Konferensbidrag (refereegranskat)abstract
- Microdialysis of the basal ganglia was used in parallel to deep brain stimulation (DBS) for patients with Parkinson’s disease. The aim of this study was to patientspecifically simulate and visualize the maximum tissue volume of influence (TVImax) for each microdialysis catheter and the electric field generated around each DBS electrode. The finite element method (FEM) was used for the simulations. The method allowed mapping of the anatomical origin of the microdialysis data and the electric stimulation for each patient. It was seen that the sampling and stimulation targets differed among the patients, and the results will therefore be used in the future interpretation of the biochemical data.
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| 6. |
- Dizdar (Dizdar Segrell), Nil, et al.
(författare)
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Comparison of N-acetylcysteine and l-2-oxothiazolidine-4-carboxylate as cysteine deliverers and glutathione precursors in human malignant melanoma transplants in mice
- 2000
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Ingår i: Cancer chemotherapy and pharmacology. - : Springer Science and Business Media LLC. - 0344-5704 .- 1432-0843. ; 45:3, s. 192-198
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Glutathione is an important cellular compound which affects detoxification of electrophiles and may have direct or indirect effects on pigment formation. It is therefore of importance to study interstitial concentrations in melanoma tissue while decreasing its formation with an enzyme inhibitor and increasing its amount with cysteine deliverers. Method: Glutathione formation was inhibited by intraperitoneal (i.p.) injection of BSO. N-Acetylcysteine (NAC) and l-2-oxothiazolidine-4-carboxylate (OTC) were then given i.p. to subgroups of the animals. Intratumoral microdialysis was performed during BSO treatment, during BSO treatment combined with NAC or OTC and after discontinuation of BSO but ongoing NAC or OTC treatment. Results: Glutathione formation was inhibited during BSO treatment. The dialysate concentrations of both glutathione and cysteine decreased during concomitant treatment with BSO and NAC or OTC. Recovery of the amounts of the two compounds was seen in both groups after discontinuation of BSO treatment. In the NAC group we also observed an acute increase in dialysate concentrations of cysteine after NAC injection. The 5-S-cysteinyldopa concentrations were unaffected by variations in glutathione and cysteine concentrations. Conclusions: 5-S-Cysteinyldopa in melanoma is not formed from glutathione in vivo to any appreciable extent. The intracellular amount of cysteine is probably not a limiting factor for cysteinyldopa formation. It seems that both NAC and OTC can be used as cysteine deliverers to melanoma cells in vivo to produce recovery of glutathione levels after synthesis inhibition by BSO treatment.
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| 7. |
- Dizdar (Dizdar Segrell), Nil, et al.
(författare)
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Effects on interstitial glutathione, cysteine and 5-S-cysteinyldopa of buthionine sulphoximine in human melanoma transplants
- 1997
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Ingår i: Melanoma research. - 0960-8931 .- 1473-5636. ; 7:4, s. 322.-328
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Tidskriftsartikel (refereegranskat)abstract
- Using microdialysis of human melanoma transplants in athymic mice we have shown that interstitial glutathione levels decreased during treatment with buthionine sulphoximine (BSO) and recovered after cessation of treatment. The cysteine concentrations also decreased, while 5-S-cysteinyldopa tended to increase during BSO treatment. Restoration of the glutathione levels was not seen after either N-acetylcysteine (NAC) or L-2-oxothiazolidine-4-carboxylate (OTC) injections, given on the third day of BSO treatment. These results were to be expected since NAC and OTC were given during the BSO treatment, and BSO is a specific and potent inhibitor of glutathione synthesis. Cysteine levels, however, increased after the NAC injection but remained unaltered after the OTC injection, while 5-S-cysteinyldopa remained unaltered after both the NAC and the OTC injections.
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| 8. |
- Dizdar (Dizdar Segrell), Nil, et al.
(författare)
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Human pharmacokinetics of L-3,4-dihydroxyphenylalanine studied with microdialysis
- 1999
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Ingår i: Clinical Chemistry. - 0009-9147 .- 1530-8561. ; 45:10, s. 1813-1820
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Tidskriftsartikel (refereegranskat)abstract
- Background: Intravenous and subcutaneous microdialysis was performedto compare the free concentrations and pharmacokinetics of L-3,4-dihyroxyphenylalanine(L-dopa) in blood and tissue in healthy subjects and in patientswith Parkinson disease.Methods: Nine healthy volunteers and 10 patients with Parkinson disease, stage 1.5–2 according to the Hoehn-Yahr rating scale, took part of the study. In the patient group subcutaneous microdialysis and ordinary blood sampling were performed, whereas in the control group intravenous microdialysis was also performed. Microdialysis samples were collected in fractions of 15 min. The first two fractions were collected for analysis of basal concentrations. A blood sample was also taken. The patients were then given one tablet of Madopar® (100 mg of L-dopa and 25 mg of benserazide),and the microdialysis was continued for another 210 min. Bloodsamples were obtained at 30-min intervals.Results: The serum samples gave a significantly higher meanarea under the curve (AUC; 491 ± 139 µmol ·min/L) than that for intravenous dialysates (235 ± 55.3µmol · min/L), suggesting a protein binding of50%. The L-dopa concentrations from the subcutaneous dialysatesmatched those from the intravenous dialysates, indicating rapiddistribution of L-dopa to the tissues.Conclusions: Parkinsonian patients in early stages of the disease have a pharmacokinetic pattern of free L-dopa similar to that of healthy subjects. Comparison of AUCs from microdialysis with ordinary serum analysis revealed data indicating significant protein binding. Microdialysis is a suitable and easily applied tool in pharmacokinetic studies.
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| 9. |
- Dizdar (Dizdar Segrell), Nil, et al.
(författare)
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L-dopa pharmacokinetics studied with microdialysis in patients with Parkinson's disease and a history of malignant melanoma
- 1999
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Ingår i: Acta neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 100:4, s. 231-237
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The pharmacokinetics of free L-dopa in blood and tissue of five parkinsonian patients with malignant melanoma was studied with microdialysis. In one case the effect of L-dopa treatment on 5-S-cysteinyldopa and the melanoma was studied. Gastric emptying and its effects on free L-dopa in blood were also investigated in one of the patients.METHODS: Five patients were given 100 mg L-dopa with 25 mg benserazide. Blood and dialysates from the circulation and fatty tissue were collected for analysis. [13C]-Octanoic breath test was used for analyzing gastric half-emptying time.RESULTS: Four of the patients had similar pharmacokinetic patterns for L-dopa and a significant (P < 0.05) increase of serum 5-S-cysteinyldopa occurring 30 min after L-dopa intake. Delayed L-dopa peaks and slow gastric half-emptying time were found in 1 patient. A dose-dependent increase of 5-S-cysteinyldopa occurred but no melanoma metastases were seen during long-term L-dopa therapy.CONCLUSION: L-dopa therapy increases 5-S-cysteinyldopa levels but does not seem to cause progress of melanomas. Gastric emptying impacts L-dopa pharmacokinetics.
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| 10. |
- Dizdar (Dizdar Segrell), Nil, et al.
(författare)
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Letter: Untitled
- 2013
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Ingår i: Journal of Neuroscience Methods. - : Elsevier. - 0165-0270 .- 1872-678X. ; 212:2, s. 363-363
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Tidskriftsartikel (refereegranskat)abstract
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| 11. |
- Farnebäck, Malin, et al.
(författare)
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Stability of blood samples for analysis of tumour cell transcripts
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- When mRNA expression from tumor cells is analyzed in blood, one of the greatest problems is to keep the samples stable during transfer to the laboratory. Improved systems for stabilization of transcripts therefore have to be developed.Blood was collected in PAXgene™ Blood RNA Tubes and spiked with melanoma and neuroblastoma cells. The stability of tumor transcripts at room temperature was tested after 1, 2, 3, 5, 7, and 9 days. PAXgene tubes were also frozen at -20 °C and -70 °C for 14 days. Total RNA was extracted by PAXgene™ Blood RNA Kit and mRNA was extracted by the GenoPrep Direct mRNA Kit. Tyrosinase, MAGE, tyrosine hydroxylase, and GD2 synthase mRNA was quantified by real-time PCR. The stability of these transcripts was compared with the stability in ACD tubes when RNA extraction was performed with QIAamp RNA Blood Mini Kit.The yields of transcripts from the PAXgene tubes using the PAXgene™ Blood RNA Kit varied from 37% to 49% of the yields from ACD tubes. When mRNA was extracted with the GenoPrep Direct mRNA Kit the yields increased to 67-121%. Stability tests showed significant decreases of all the transcripts in the PAXgene tubes after two days at room temperature. After seven days, 10% of the initial transcript concentrations remained, whereas 32% remained in the ACD tubes. However, in the frozen PAXgene tubes the transcript levels were unchanged for 14 days.We conclude that the PAXgene tube is suitable when the sample is stored at -20 °C or -70 °C and mRNA is extracted using GenoPrep Direct mRNA Kit.
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| 12. |
- Kågedal, Bertil, 1943-, et al.
(författare)
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Pterin-dependent tyrosine hydroxylase mRNA is not expressed in human melanocytes or melanoma cells
- 2004
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Ingår i: Pigment Cell Research. - : Wiley. - 0893-5785 .- 1600-0749. ; 17:4, s. 346-351
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Tidskriftsartikel (refereegranskat)abstract
- Pterin-dependent tyrosine hydroxylase has been described to occur occasionally in melanocytes. It is therefore important to quantify the mRNA of this enzyme in pigment cells to understand whether this enzyme can take an active part in pigment formation. A real-time reverse transcription-polymerase chain reaction method was used to quantify tyrosine hydroxylase mRNA in melanocytes and melanoma cells. The calibrator was obtained by amplification of a segment of cDNA from tyrosine hydroxylase mRNA, which included the target thus allowing enumeration of the number of transcripts per cell. In melanocytes (n = 3), tyrosine hydroxylase mRNA ranged from non-detectable to 0.000492 transcripts/cell and in melanoma cells from non-detectable to 0.005340 transcripts/cell. In neuroblastoma cells, the median tyrosine hydroxylase mRNA number was 0.4 transcripts/cell (range 0.02-25 transcripts/cell). The amount of tyrosine hydroxylase mRNA in the pigment cells was far less than the mRNA concentrations of four melanocyte-specific proteins measured in the same melanocytes and melanoma cells. We conclude that on the average less than 1 of 1000 melanocytes and melanoma cells contains at least one tyrosine hydroxylase mRNA molecule. Consequently, in 999 of 1000 cells translation into the corresponding enzyme protein cannot occur because of the lack of an mRNA template. Thus, in these cells there is no pterin-dependent tyrosine hydroxylase that can contribute to pigment formation by producing priming amounts of L-dopa for proper function of tyrosinase.
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| 13. |
- Nord, Maria, et al.
(författare)
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Is Levodopa Pharmacokinetics in Patients with Parkinson’s Disease Depending on Gastric Emptying?
- 2017
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Ingår i: Advances in Parkinsons Disease. - : Scientific Research Publishing. - 2169-9712 .- 2169-9720. ; 06:01
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Tidskriftsartikel (refereegranskat)abstract
- Levodopa uptake from the gastrointestinal tract in patients with Parkinson’s disease (PD) can be affected by delayed gastric emptying (GE). This might lead to fluctuating levodopa levels resulting in increased motor fluctuations. Continuous dopaminergic stimulation (CDS) improves motor fluctuations and could be a result of smoothening in levodopa uptake. In this study we wanted to study the levodopa pharmacokinetics peripherally in PD patients with motor fluctuations and investigate the relation between levodopa uptake and GE and the effect of CDS. PD patients with wearing off (group 1) and on-off syndrome (group 2) were included. Breath tests were performed to evaluate the half time (T1/2) of GE. Concomitantly 1 tablet of Madopark® was given and the levodopa concentrations in blood and subcutaneous (SC) tissue were analyzed for both groups. Group 2 was then given a 10-d continuous intravenous levodopa treatment and the tests were repeated. Higher levels of levodopa in group 1 compared to group 2 in blood (p = 0.014) were seen. The GE was delayed in both group 1 (p < 0.001) and group 2 (p < 0.05) compared to a reference group with healthy volunteers with T1/2 median values 105 and 78 min vs. 72 min. There was no difference in GE between the two PD groups (p = 0.220) or in group 2 before and after infusion period (p = 0.861). CDS resulted in lower levodopa levels in blood (p < 0.001) and SC tissue (p < 0.01). In conclusion, PD patients in early complication phase have a more favourable levodopa uptake than patients later in disease. We found delayed GE in PD patients with motor fluctuations but no obvious relation between GE and levodopa uptake or GE and PD stage. The effect of CDS indicates no effect of CDS on the mechanisms of GE but on the mechanisms of levodopa uptake.
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| 14. |
- Nord, Maria, et al.
(författare)
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Levodopa Pharmacokinetics in Brain after Both Oral and Intravenous Levodopa in One Patient with Advanced Parkinson’s Disease
- 2017
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Ingår i: Advances in Parkinsons Disease. - : Scientific Research Publishing Inc. - 2169-9712 .- 2169-9720. ; 6:2, s. 52-66
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Tidskriftsartikel (refereegranskat)abstract
- Objective: One patient received oral levodopa during a study aiming for better understanding of the basal ganglia and of the mechanisms of deep brain stimulation of the subthalamic nucleus (STN DBS) with and without intravenous (IV) levodopa infusion in patients with Parkinson’s disease (PD). The results from oral and IV levodopa treatment are presented.Methods: Five patients with advanced PD were included in the original study. During planned STN DBS surgery microdialysis probes were implanted in the right putamen and in the right and left globus pallidus interna (Gpi). During the study, microdialysis was performed continuously and STN DBS, with and without IV levodopa infusion, was performed according to a specific protocol. After DBS surgery, but before STN DBS was started, one patient received oral levodopa/ benserazide and entacapone tablets out of protocol due to distressing parkinsonism.Results: The levodopa levels increased prompt in the central nervous system after the first PD medication intakes but declined after the last. Immediately the levodopa seemed to be metabolized to dopamine (DA) since the levels of DA correlated well with levodopa concentrations. Left STN DBS seemed to further increase DA levels in left Gpi while right STN DBS seemed to increase DA levels in the right putamen and right Gpi. There was no obvious effect on levodopa levels.Conclusions: The results indicate that PD patients still have capacity to metabolize levodopa to DA despite advanced disease with on-off symptoms and probably pronounced nigral degeneration. STN DBS seems to increase DA levels with a more pronounced effect on ipsilateral structures in striatum.
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| 15. |
- Nord, Maria, et al.
(författare)
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The Effect of Peripheral Enzyme Inhibitors on Levodopa Concentrations in Blood and CSF
- 2010
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Ingår i: Movement Disorders. - : John Wiley & Sons. - 0885-3185 .- 1531-8257. ; 25:3, s. 363-367
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Tidskriftsartikel (refereegranskat)abstract
- Levodopa combined with a dopa-decarboxylase inhibitor, such as carbidopa. shifts the metabolism to the COMT pathway. Adding the peripheral acting COMT inhibitor entacapone provides improvement for patients with PD suffering from motor fluctuations. We studied the effects of the enzyme inhibitors entacapone and carbidopa on the levodopa concentrations in CSF and in blood. Five PD patients with wearing-off underwent lumbar drainage and intravenous microdialysis. Samples were taken 12 h daily for 3 days. Day I; intravenous levodopa was given, day 2; additional oral entacapone 200 mg tid, day 3; additional oral entacapone 200 mg bid and carbidopa 25 mg bid. Levodopa in CSF and in dialysates was analysed. The AUC for levodopa increased both in blood and CSF when additional entacapone was given alone and in combination with carbidopa. The C-max of levodopa in both CSF and blood increased significantly. Additional entacapone to levodopa therapy gives an increase of C-max in CSF and in blood. The increase is more evident when entacapone is combined with carbidopa.
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| 16. |
- Trager, Catarina, et al.
(författare)
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mRNAs of tyrosine hydroxylase and dopa decarboxylase but not of GD2 synthase are specific for neuroblastoma minimal disease and predicts outcome for children with high-risk disease when measured at diagnosis
- 2008
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 123:12, s. 2849-2855
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Tidskriftsartikel (refereegranskat)abstract
- Several transcripts have been claimed to be clinically valuable for detecting minimal disease in neuroblastoma, but they have not been prospectively compared in a standardized manner. Tyrosine hydroxylase (TH), dopa decarboxylase (DDC) and GD2 synthase (GD2S) mRNAs were analyzed in 554 blood (PB) and bone marrow (BM) samples from 58 children with neuroblastoma. Samples from 44 children with other diseases served as controls. High transcript concentrations of TH, GD2S or DDC in PB or BM at diagnosis were associated with poor prognosis. TH in BM above median indicated worse outcome for a homogenous cohort with high-risk neuroblastoma (survival probability 91% for TH below median versus 33% for TH above median, p = 0.009). The number of children with localized neuroblastoma with increased results in PB did not differ between the three transcripts. In these children, all without morphologically detectable neuroblastoma in BM, the number of patients with elevated GD2S in BM at diagnosis was significantly higher than for the other transcripts (10/16 elevated, P = 0.012). GD2S was elevated in PB from 10/28 controls without neuroblastoma compared to 1/28 for TH and DDC (p < 0.001). In BM from these children GD2S was significantly elevated. We conclude that high expression of TH and DDC both in Ill and BM corresponds to metastatic neuroblastoma at diagnosis, residual disease, and poor outcome. Children with high-risk neuroblastoma and low levels of TH in BM at diagnosis may be cured by current therapy. GD2S is less specific than TH and DDC mRNA for neuroblastoma detection in PB and BM.
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| 17. |
- Träger, Chatarina, 1962-, et al.
(författare)
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Quantitative analysis of tyrosine hydroxylase mrna for sensitive detection of neuroblastoma cells in blood and bone marrow
- 2003
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 49:1, s. 104-112
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Tidskriftsartikel (refereegranskat)abstract
- Background: Sensitive monitoring of minimal residual disease may improve the treatment of neuroblastoma in children. To detect and monitor neuroblastoma cells in blood and bone marrow, we developed a quantitative method for the analysis of tyrosine hydroxylase mRNA. Methods: We used real-time reverse transcription-PCR. The calibrator was constructed from a segment of tyrosine hydroxylase mRNA that included the target. Blood and bone marrow samples from 24 children with neuroblastoma and 1 child with ganglioneuroma were analyzed. Controls were blood samples from the cords of 40 babies, from 58 children 6 months to 15 years of age, and from 34 healthy adults, as well as from 12 children with other diseases. Results: The detection limit was ~70 transcripts/mL. All 144 blood controls were below this limit. At diagnosis, blood tyrosine hydroxylase mRNA was higher in children with widespread disease (stage 4/4S, n = 6, range, 203-46 000 transcripts/mL) than in patients with localized disease (stages 1-3, n = 6, =83 transcripts/mL, P = 0.002). Bone marrow from all five children with localized disease had concentrations <72 transcripts/mL, whereas five of six stage 4 patients had increased concentrations (6000-8 000 000 transcripts/mL, P <0.05). In nine children in whom tyrosine hydroxylase mRNA was measured repeatedly, the results corresponded to the clinical course. Conclusion: Quantitative analysis of tyrosine hydroxylase mRNA in blood and bone marrow is reliable and easy to perform and may be used for upfront staging, prognostic assessment, and treatment monitoring of neuroblastoma.
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| 18. |
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| 19. |
- Zsigmond, Peter, et al.
(författare)
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Neurotransmitter levels in basal ganglia during L-dopa and Deep Brain Stimulation treatment in Parkinson’s Disease
- 2013
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Bilateral deep brain stimulation of the nucleus subthalamicus (STN DBS) is a wellestablishedtreatment in patients with advanced Parkinson’s disease (PD). The mechanism bywhich STN DBS improves the PD symptoms remains unclear. In a previous perioperativestudy we have shown that there might be alterations of neurotransmitter levels in the Globuspallidum interna (GPi) during STN DBS. In this study we wanted to examine if STN DBSand L-dopa infusion interact and affect the levels of neurotransmitters.Methods: Five patients with advanced PD took part in the study. During STN surgery microdialysis catheters were inserted bilaterally in the GPi and unilaterally in the right putamen. A study protocol was set up and was followed for three days including STN DBS left side, right side and bilateral. L-dopa infusion with and without concomitant bilateral STN DBS was also performed.Results: The putaminal dopamine levels increase during STN DBS. In addition an increase of GABA concentrations in the GPi during STN DBS and during L-dopa infusion was found.Conclusions: These findings can provide evidence that the STN has a direct action on the substantia nigra pars compacta (SNc) and that STN DBS may indirectly release putaminal dopamine. There is also evidence that STN DBS interferes with L-dopa therapy resulting in higher levels of Ldopa in the brain explaining why its possible to decrease L-dopa medication after DBS surgery.
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| 20. |
- Zsigmond, Peter, et al.
(författare)
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Neurotransmitter levels in basal ganglia during levodopa and deep brain stimulation treatment in Parkinson’s disease
- 2014
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Ingår i: Neurology and Clinical Neuroscience. - : John Wiley & Sons. - 2049-4173. ; 2:5, s. 149-155
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Tidskriftsartikel (refereegranskat)abstract
- Background The mechanism by which deep brain stimulation of the nucleus subthalamicus improves Parkinson’s disease symptoms remains unclear. In a previous perioperative study, we showed that there might be alterations of neurotransmitter levels in the globus pallidum interna during deep brain stimulation of the nucleus subthalamicus. Aim In this study, we examined whether deep brain stimulation of the nucleus subthalamicus and levodopa infusion interact and affect the levels of neurotransmitters. Methods Five patients with advanced Parkinson’s disease took part in the study. During subthalamic nucleus surgery, microdialysis catheters were inserted bilaterally in the globus pallidum interna and unilaterally in the right putamen. A study protocol was set up and was followed for 3 days. Levodopa infusion with and without concomitant bilateral deep brain stimulation of the nucleus subthalamicus was also carried out. Results The putaminal dopamine levels increased during deep brain stimulation of the nucleus subthalamicus. In addition, an increase of gamma amino buturic acid concentrations in the globus pallidum interna during deep brain stimulation of the nucleus subthalamicus and during levodopa infusion was found. Conclusions These findings provide evidence that the subthalamic nucleus has a direct action on the substantia nigra pars compacta, and that deep brain stimulation of the nucleus subthalamicus might indirectly release putaminal dopamine. There is also evidence that deep brain stimulation of the nucleus subthalamicus interferes with levodopa therapy resulting in higher levels of levodopa in the brain, explaining why it is possible to decrease levodopa medication after deep brain stimulation surgery.
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| 21. |
- Zsigmond, Peter, et al.
(författare)
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Stereptactic microdialysis of the basal ganglia in Parkinson's disease
- 2012
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Ingår i: Journal of Neuroscience Methods. - : Elsevier. - 0165-0270 .- 1872-678X. ; 207:1, s. 17-22
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Tidskriftsartikel (refereegranskat)abstract
- Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an efficacious treatment in patients with advanced Parkinson's disease, yet the mechanisms of STN DBS are poorly understood. The aims of this study were to develop a useful method for studying neurotransmitter alterations during DBS and for the pharmacokinetics of L-dopa in brain tissue. Ten patients with Parkinson's disease participated, whereof two had no previous L-dopa medication. The electrodes and catheters were placed using MRI-guided stereotaxic targeting. Two microdialysis probes were placed, one in the right internal globus pallidus, and one in a brachial vein. The quadripolar deep brain electrodes were placed in the right STN. Microdialysates from brain tissue and blood were collected in 15-min fractions at baseline and during DBS. After stimulation new baseline fractions were taken and finally three fractions during continuous intravenous infusion of L-dopa. Clinical evaluation showed that both DBS and L-dopa infusion gave good relief of rigidity and tremor in all ten patients. During DBS the L-dopa levels in the brain increased in some of the patients but did not persist during the whole stimulation period. The concentration in brain increased substantially during intravenous L-dopa infusion. A number of catecholamines and their metabolites were analysed with high pressure liquid chromatography (HPLC). With our study we could show that this model is suitable for the monitoring of neurotransmitters and for pharmacokinetic studies in human brain, although we found that the sampling time was too short to follow the possible alterations in brain activity caused by DBS.
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| 22. |
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