Biomedical subjects

H J Wagner

Publications and source records attributed to H J Wagner.

At least 19 recordsLinked to original sources

PubMed2004

Regulation of intestinal phosphate cotransporter NaPi IIb by ubiquitin ligase Nedd4-2 and by serum- and glucocorticoid-dependent kinase 1.

Serum and glucocorticoid-inducible kinase 1 (SGK1) is highly expressed in enterocytes. The significance of the kinase in regulation of intestinal function has, however, remained elusive. In Xenopus laevis oocytes, SGK1 stimulates the epithelial Na(+) channel by phosphorylating the ubiquitin ligase Nedd4-2, which regulates channels by ubiquitination leading to subsequent degradation of the channel protein. Thus the present study has been performed to explore whether SGK1 regulates transport systems expressed in intestinal epithelial cells, specifically type IIb sodium-phosphate (Na(+)-P(i)) cotransporter (NaPi IIb). Immunohistochemistry in human small intestine revealed SGK1 colocalization with Nedd4-2 in villus enterocytes. For functional analysis cRNA encoding NaPi IIb, the SGK isoforms and/or the Nedd4-2 were injected into X. laevis oocytes, and transport activity was quantified as the substrate-induced current (I(P)). Exposure to 3 mM phosphate induces an I(P) in NaPi IIb-expressing oocytes. Coinjection of Nedd4-2, but not the catalytically inactive mutant (C938S)Nedd4-2, significantly downregulates I(P), whereas the coinjection of (S422D)SGK1 markedly stimulates I(P) and even fully reverses the effect of Nedd4-2 on I(P). The effect of (S422D)SGK1 on NaPi IIb is mimicked by wild-type SGK3 but not by wild-type SGK2, constitutively active (T308D,S473D)PKB, or inactive (K127N)SGK1. Moreover, (S422D)SGK1 and SGK3 phosphorylate Nedd4-2. In conclusion, SGK1 stimulates the NaPi IIb, at least in part, by phosphorylating and thereby inhibiting Nedd4-2 binding to its target. Thus the present study reveals a novel signaling pathway in the regulation of intestinal phosphate transport, which may be important for regulation of phosphate balance.

Animals↗

PubMed2002

Time-resolved, undersampled projection reconstruction imaging for high-resolution CE-MRA of the distal runoff vessels.

Imaging of the blood vessels below the knee using contrast-enhanced (CE) MRI is challenging due to the need to coordinate image acquisition and arrival of the contrast in the targeted vessels. Time-resolved acquisitions have been successful in consistently capturing images of the arterial phase of the bolus of contrast agent in the distal extremities. Although time-resolved exams are robust in this respect, higher spatial resolution for the depiction of tight stenoses and the small vessels in the lower leg is desirable. A modification to a high-spatial-resolution T(1)-weighted pulse sequence (projection reconstruction-time resolved imaging of contrast kinetics (PR-TRICKS)) that improves the through-plane spatial resolution by a factor of 2 and maintains a high frame rate is presented. The undersampled PR-TRICKS pulse sequence has been modified to double the spatial resolution in the slice direction by acquiring high-spatial-frequency slice data only after first pass of the bolus of contrast agent. The acquisition reported in the present work (PR-hyperTRICKS) has been used to image healthy volunteers and patients with known vascular disease. The temporal resolution was found to be beneficial in capturing arterial phase images in the presence of asymmetric filling of vessels.

Contrast Media↗

PubMed2002

[Current status of endovascular therapy in the femoropopliteal vascular segment in chronic peripheral arterial occlusive disease].

Technical success of endovascular measures in the femoropopliteal region has increased since the introduction of new technology (hydrophilic guide-wires, stents, stent grafts) in the last decade to rates of more than 90%. If the initial revascularization--even of long segment occlusions--is successful, the modern armamentarium of interventional radiology enables to keep the vessel open acutely. Evidence, that the immediate success of revascularization leads to a continuous improvement of the clinical symptoms, measured by clinically relevant end points (e.g. improvement of walking distance, increase of limb salvage, increase of survival), has yet to be shown. Several prospective randomized trials demonstrated improvement of walking distance after one year follow-up, but not after two years follow-up in patients with chronic femoropopliteal obstructions, who were treated with PTA compared to walking exercise only. The only two prospective randomized trials comparing vascular surgery and endovascular therapy for femoropopliteal obstructions could not demonstrate any advantage of one of the two modalities in patients with claudication or critical ischemia. The transatlantic consensus document (TASC) recommends PTA as therapy of choice in the femoropopliteal arteries only for single stenosis < 3 cm and does not recommend primary stenting. In order to evaluate endovascular therapy in the femoropopliteal region outcome studies are needed, which carefully assess clinically relevant end points like improvement of walking distance, limb salvage, and survival, but also disease specific quality of life evaluations. Several meta-analyses, performed in recent years, have demonstrated that endovascular therapy has a definite role in the femoropopliteal segment. However, the particular role has to be evaluated for the individual clinical case in the light of case-specific findings and symptoms.

Angioplasty, Balloon↗

PubMed2002

Magnetic resonance phase contrast velocity measurement for non-invasive follow up after percutaneous transluminal angioplasty.

BACKGROUND: The aim of this study was to evaluate magnetic resonance phase contrast velocimetry (MRVL) as a non-invasive follow up tool to assess restenosis after percutaneous transluminal angioplasty (PTA). PATIENTS AND METHODS: We prospectively investigated 51 consecutive patients who underwent PTA of the femoropopliteal region. MRVL was conducted prior, one day, six weeks, twelve weeks and 24 weeks after PTA using a circular polarized extremity coil and a gradient echo sequence (TR/TE 600/6 ms, flip angel 30 degrees, slice thickness 10 mm). Hemodynamic data, derived from the MR phase contrast sequence, allowed to calculate the degree of area stenosis of the lesion treated with PTA. These data were correlated with clinical hemodynamic parameters (ankle-brachial index and walking distance). RESULTS: The mean grade of area stenosis was 69% +/- 27% before PTA, 30% +/- 20% one day, 29% +/- 23% six weeks, 39% +/- 17% twelve weeks and 42% +/- 18% 24 weeks after PTA and correlated well with clinical data and the post angioplasty clinical course of the patients. CONCLUSIONS: Follow up measurements using MRVL are suitable to assess restenosis after PTA and allow quantifying the grade of recurrent stenosis as well as the hemodynamic consequences.

Aged↗

PubMed2002

Magnetic resonance hydrometry: non-invasive quantification of the exocrine pancreatic function.

AIMS: To show the ability of magnetic resonance hydrometry (MRH) to quantify the pancreatic secretion after secretin stimulation in order to distinguish between physiological excretion and reduced output in chronic pancreatitis. METHODS: MRH images were acquired in a 1.0-T-clinical scanner using a body-array coil and a heavily T2-weighted standard single-shot TSE sequence. Thirty-one patients (14 male/17 female) who routinely underwent ERCP for suspected choledocholithiasis (n = 22), recurring abdominal pain (n = 1), icterus (n = 6 and suspected pancreatitis (n = 2) were included. During the investigation 1 CU/kg BW secretin were administered intravenously. Secreted volume of fluid, start of secretion, achievement of a plateau of secretion and a combined score of these parameters (MRH score) were assessed and evaluated. Sensitivity and specificity were calculated for these parameters. RESULTS: 27 patients had no pancreatic pathology, and four suffered from chronic pancreatitis. Patients without pancreatic disorders produced a mean pancreatic fluid volume of 183 plus minus 86 mL, whereas patients with chronic pancreatitis secreted 61 +/- 39 mL. Secretion started after a mean time of 95 +/- 94 seconds (no pancreatic impairment) and 62 +/- 13 seconds (chronic pancreatitis). The MRH score achieved a high accuracy in the detection of chronic pancreatitis. CONCLUSIONS: Our study demonstrated the feasibility of measuring pancreatic output by MRH after stimulation with secretin. Moreover, a distinction between normal secretion and patients with chronic pancreatitis is possible.

Adult↗

PubMed2002

Rotational digital cholangiography (RDC) and 3D-cholangiography (3DC) for guidance of percutaneous biliary drainage procedures.

PURPOSE: To evaluate whether RDC and 3DC help clarifying anatomic details in biliary duct disease and is useful for guidance of drainage procedures. MATERIALS AND METHODS: RDC was conducted in 11 consecutive patients (8 male, 3 female, mean age 63 years). Nine patients underwent PTBD for malignant biliary duct stenosis, one patient because of ischemic stenosis after hepaticojejunostomy and one patient presented with an infected biloma. Images were obtained after initial bile duct puncture during single breath hold from 120 projection angles using a rotating C-arm. These images were immediately available and evaluated in order to facilitate the definitive drainage procedure. For additional 3D reconstruction, data were sent to a dedicated workstation and judged by a blinded observer. RESULTS: The availability of a rotating data set of images was judged to be helpful in three patients with complex anatomical situations. Additionally, RDC holds the potential to reduce fluoroscopy time. 3DC allowed analysis of the hepatic bifurcation from different viewing angles in 10 cases with high spatial resolution (mean voxel size 480 micro micro m 3). This may allow a better classification of hilar obstructions according to our preliminary observations. CONCLUSION: Images from RDC and 3DC are helpful in guiding PTBD procedures and for better diagnosis in selected patients with hilar biliary duct stenoses.

Adult↗

PubMed2002

Immunotherapy for Hodgkin's disease.

EBV proteins present in the malignant Hodgkin Reed-Sternberg (HR-S) cells of about 40% of patients with Hodgkin's Disease (HD) provide targets for immunotherapy with virus-specific cytotoxic T lymphocytes (CTL). However, Hodgkin tumors use multiple strategies to avoid CTL, including down-regulation of immunodominant EBV antigens, and secretion of cytokines and chemokines such as TGF-beta, that inhibit the activation of CTL and professional antigen-presenting cells (APC). To be effective against this tumor, CTL must resist some or all of these strategies. Thirteen patients with multiply-relapsed HD received EBV-specific CTL, generated ex vivo using the autologous EBV-transformed B cells (LCL) as stimulator cells. After CTL infusion, EBV-specific immunity increased, virus load decreased, CTL homed to sites of malignancy and persisted for up to ten months. Clinically, CTL produced resolution of B symptoms and mixed tumor responses including one complete remission of residual disease remaining after autologous bone marrow transplant. However, no complete remission of bulky disease was achieved. Although LMP2-specific CTL activity could be detected in some of the infused CTL lines, they were present in low frequency. In pre-clinical studies, LMP1 and LMP2-specific CTL could be produced by stimulating PBMC from patients and normal donors with autologous dendritic cells expressing LMP1 or LMP2 from adenoviral vectors. Further, CTL could be rendered resistant to the devastating effects of TGF-beta by transduction with a retrovirus vector expressing a dominant-negative TGF-beta receptor, while transgenic IL-12 could increase the expression of Th1 and decrease that of Th2 cytokines. Future clinical studies will test the efficacy of CTL with improved antigen-specificity and resistance to Hodgkin immune evasion strategies.

Antigens, Viral↗

PubMed2001

Pineal organs in deep demersal fish.

We studied ten species of demersal fish from depths of 1500-4800 m, i.e. regions of the abyss outside the reach of sunlight. A pineal window in the skin and/or the skull, often found in mesopelagic fish, was never observed in demersal specimens. Nine species had a well-developed pineal organ, with light- and electron-microscopic features, well known in other teleosts living in surface waters, including photoreceptor cells with inner and outer segments, synaptic ribbons, neuronal perikarya, and (radial) glial cells. One species ( Bathypterois dubius) showed signs of regression; it also had reduced eyes. We observed considerable morphological variation in location, size, microscopic structure and ultrastructural organisation, including the frequency of photoreceptor cells, size of outer segments and the number of myelinated and unmyelinated axons. No systematic trend in the sense of an increase of sensitivity with greater depths was observed. Melatonin contents varied between 4 pg and 92 pg per pineal in the grenadier Coryphaenoides ( Nematonurus) armatus and between 2 pg and 70 pg per pineal in the eel Synaphobranchus kaupi. Differences between day and night values and between autumn and spring suggest that pineal melatonin acts as neurochemical signal mediating rhythmic processes and behaviour. The role of an alternative non-solar zeitgeber in the demersal environment is discussed.

Animals↗

PubMed2001

Cerebral localization and regulation of the cell volume-sensitive serum- and glucocorticoid-dependent kinase SGK1.

The serum- and glucocorticoid-dependent kinase SGK1 is regulated by alterations of cell volume, whereby cell shrinkage increases and cell swelling decreases the transcription, expression and activity of SGK1. The kinase is expressed in all human tissues studied including the brain. The present study was performed to localize the sites of SGK1 transcription in the brain, to elucidate the influence of the hydration status on SGK1 transcription and to explore the functional significance of altered SGK1 expression. Northern blot analysis of human brain showed SGK1 to be expressed in all cerebral structures examined: amygdala, caudate nucleus, corpus callosum, hippocampus, substantia nigra, subthalamic nucleus and thalamus. In situ hybridization and immunohistochemistry in the rat revealed increased expression of SGK1 in neurons of the hippocampal area CA3 after dehydration, compared with similar slices from brains of euvolaemic rats. Additionally, several oligodendrocytes, a few microglial cells, but no astrocytes, were positive for SGK1. The abundance of SGK1 mRNA in the temporal lobe, including hippocampus, was increased by dehydration and SGK1 transcription in neuroblastoma cells was stimulated by an increase of extracellular osmolarity. Co-expression studies in Xenopus laevis oocytes revealed that SGK1 markedly increased the activity of the neuronal K+ channel Kv1.3. As activation of K+ channels modifies excitation of neuronal cells, SGK1 may participate in the regulation of neuronal excitability.

Animals↗

PubMed2001

Patients at risk for development of posttransplant lymphoproliferative disorder: plasma versus peripheral blood mononuclear cells as material for quantification of Epstein-Barr viral load by using real-time quantitative polymerase chain reaction.

BACKGROUND: Early diagnosis of Epstein-Barr virus (EBV)-associated posttransplant lymphoproliferative disorder (PTLD) is required to detect a stage of disease that is more likely to respond to treatment. Elevated levels of EBV DNA were found in peripheral blood of patients at the onset of PTLD. METHODS: To compare plasma and peripheral blood mononuclear cells (PBMCs) as material for real-time quantitative polymerase chain reaction (RQ-PCR) measurement of Epstein-Barr viral load, we used two sets of primers and probes specific for the BAM HI-K or BAM HI-W region of the EBV genome. RESULTS: Patients with PTLD had a median viral load of 19,200 EBV genomes/microg DNA (n=9) or 3,225 EBV genomes/100 microl plasma (n=5), being significantly higher compared with immunosuppressed patients with primary (n=9) or reactivated (n=20) EBV infection or immunosuppressed patients without serological signs of active EBV infection (n=67) (P<0.001). Hence, a value of greater than 5,000 EBV genomes/microg PBMC DNA was considered as a diagnostic parameter for PTLD with a sensitivity and specificity of 1.00 or 0.89, respectively. When plasma was analyzed, however, a value of greater than 1,000 EBV genomes/100 microl plasma had both a sensitivity and specificity of 1.00 for the diagnosis of PTLD. During remission of PTLD, viral load was more effectively cleared in plasma compared with PBMCs. In plasma of nonimmunosuppressed individuals, even a qualitative detection of EBV-related sequences was sensitive and specific for the diagnosis of primary EBV infection, whereas for analysis of PBMC DNA a quantitative parameter had to be considered to differentiate healthy individuals (< 100 EBV genomes/microg PBMC DNA) from patients with primary EBV infection (>100 EBV genomes/microg PBMC DNA). CONCLUSION: Although both PBMCs and plasma were useful as material for EBV-specific RQ-PCR in immunosuppressed patients and nonimmunosuppressed individuals, the specificity of analysis seemed to be higher if plasma was taken for analysis.

Adolescent↗

PubMed2001

[Endovascular stent graft support exclusion of an infrarenal aortic aneurysm using gadolinium as contrast medium in kidney insufficiency].

HISTORY: A 64-year-old obese man with radiocontrast-induced nephropathy, which required temporary hemodialysis, was referred for treatment of an infrarenal abdominal aortic aneurysm detected incidentally. Comorbidities were obesity (BMI 44.1), non-insulin dependent diabetes mellitus, arterial hypertension, COPD, and renal failure with decompensated retention. INVESTIGATIONS: MRI demonstrated a 6.1 cm diameter infrarenal partially thrombosed aortic aneurysm which extended to the aortic bifurcation. Its morphology was favourable for endovascular treatment. TREATMENT AND COURSE: An aortobiiliac stent graft was inserted after bilateral arterial femoral cut-down. As a contrast agent we administered 0.5 molar gadoteridol solution only. The total volume used was 90 ml (0.375 mmol/kg body weight). The aneurysm was completely excluded. No further signs of renal deterioration occurred. CONCLUSION: Non-nephrotoxic gadolinium-containing contrast media allow minimal invasive exclusion of infrarenal aortic aneurysms with use of stent grafts in patients in whom conventional iodinated x-ray contrast agents are contraindicated.

Aortic Aneurysm, Abdominal↗

PubMed2001

Kinetic evaluation of an i.v. bolus of MR contrast media.

Currently, it is assumed that the pharmacokinetic properties of the first minutes of an I.V. MR contrast media bolus are similar to those of an i.v. iodinated contrast media bolus used in CT. Correct timing of an MRA examination is crucial for obtaining sufficient arterial contrast. This study sought to evaluate the temporal change of arterial signal intensity within 150 s after i.v. bolus injection of Gd-DTPA. Thirty consecutive patients (14 women/16 men; mean age: 51 +/- 11 years) were prospectively examined with a 1.0 Tesla clinical scanner. A single axial slice was acquired in 1.25 sec with manufacturer provided gradient echo sequence through the aorta at the level of the renal arteries. Investigation was started simultaneously to the application of contrast media (0.1 mmol/kg bodyweight Gd-DTPA at three different rates 2 mL/sec, 3 mL/sec and 4 mL/sec) and repeated for 2.5 min. An additional echo Doppler examination excluded patients with any cardiac disorders. Maximum signal (1300% increase compared to the basic value) in the aorta was achieved 20 +/- 6 sec after start of bolus injection. Then a plateau phase was maintained for the remaining investigation time (2.5 min). No significant difference was shown for different injection rates. After a bolus injection of Gd-DTPA the arterial contrast remains on a high level for at least 2 min. However, correct timing of the bolus arrival is still crucial to discriminate arteries and veins. An injection rate between 2 mL/sec and 4 mL/sec has no influence on early contrast media dynamics.

Aorta↗

PubMed2001

Detection of Epstein-Barr virus DNA in peripheral blood of paediatric patients with Hodgkin's disease by real-time polymerase chain reaction.

Hodgkin's disease (HD) is commonly associated with latent Epstein-Barr virus (EBV) infection. The aim of our study was a detailed molecular analysis of the EBV status in the peripheral blood of paediatric patients with HD. Blood samples from HD patients were examined before (n=28) and after treatment (n=12). The control group consisted of 20 healthy children and 10 immunosuppressed children with primary EBV infection. EBV load in plasma and peripheral blood mononuclear cells (PBMC) were determined by real time quantitative polymerase chain reaction (RQ-PCR) as recently described. Before treatment, EBV DNA was detected in the plasma of 13/24 EBV-seropositive HD patients, whereas in plasma of healthy controls no EBV DNA was detectable (P<0.001). After treatment, no EBV genomes were found in the plasma of 6 HD patients in stable and complete remission. In contrast, 2/5 HD patients with relapse of disease were positive for EBV DNA in the plasma. In PBMCs, no differences were found in EBV load measured in HD patients before or after treatment and healthy controls. A high EBV load was found in both the plasma and PBMCs of all immunosuppressed patients with primary EBV infection. Thus, EBV DNA detection in the plasma of paediatric HD patients might be of value for non-invasive diagnostic, prognostic and follow-up tests for HD.

Adolescent↗

PubMed2001

Prospective comparison of MR phase-contrast velocimetry with intravascular doppler US during infrainguinal artery angioplasty.

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) velocimetry for quantitative assessment of stenosis in patients undergoing percutaneous transluminal angioplasty (PTA). MATERIALS AND METHODS: Thirty patients underwent PTA of the infrainguinal region. To assess hemodynamic parameters of lesions, MR phase-contrast velocimetry with a circular-polarized extremity receiver coil and a cardiac gated gradient echo sequence was conducted before and 1 day after PTA. Additionally, all lesions were examined by means of intravascular Doppler flow measurements (0.018-inch wire, 12 MHz). From these data, the degree of stenosis was calculated and a comparison of MR velocimetry with intravascular Doppler US was undertaken. RESULTS: Correlation between calculated grade of stenosis for MR velocimetry and intravascular Doppler US was good and significant (r = 0.74; P <.001). Calculated luminal stenosis grade were similar for both methods before PTA (intravascular Doppler US: 0.62 +/- 0.18, MR velocimetry: 0.54 +/- 0.19; P =.17 with paired Student t-test) and after PTA (0.25 +/- 0.23 and 0.3 +/- 0.2, respectively; P =.56). CONCLUSION: MR velocimetry results in reliable noninvasive in vivo flow measurements and allows accurate assessment of stenosis in a clinical setting.

Aged↗

PubMed2001

In vivo evaluation of an intravascular receiver coil for MRI at 1.0 Tesla.

BACKGROUND: Evaluation of the applicability of intravascular radiofrequency receiver coils by means of a pig in-vivo-experiment for the detection of vessel wall structures at 1.0 Tesla. MATERIALS AND METHODS: The intravascular receiver coil was constructed according to a well evaluated single-loop-design, which was mounted onto a balloon catheter for angioplasty. Under fluoroscopy control the balloon catheter was placed in the common carotid artery of a porcine. Images were obtained in a 1.0 Tesla clinical scanner using a fast-spin-echo-, a gradient-echo- and a high resolution spin-echo-sequence. Histological examinations were obtained to detect any vessel wall damage associated with the use of the receiver coil. RESULTS: High quality images with a resolution up to 0.16*0.12 mm2 could be acquired in aquisition times of about 5 minutes. Subtle intra- and extra-vascular structures such as the balloon, irregularities of the vessel wall or bordering structures could be visualized. The histological examination showed no vessel damage due to the application of the intravascular receiver coil. CONCLUSIONS: The application of intravascular receiver coils for the visualization of the vessel wall is feasible at 1.0 Tesla without histologically detectable trauma to the vessel wall.

Animals↗

PubMed2001

The use of gadolinium chelates for X-ray digital subtraction angiography.

RATIONALE AND OBJECTIVES: To evaluate the feasibility and safety of using gadolinium chelates for x-ray digital subtraction angiography (DSA) in patients with contraindications to iodinated contrast material. METHODS: We performed 30 DSAs in 22 patients (5 females, 17 males; mean age 64.9 years) with contraindications to iodinated contrast media (renal insufficiency: n = 28; hyperthyroidism: n = 1; contrast allergy: n = 2). Gadolinium chelates were administered as 0.5 mol/L solutions (mean volume of gadolinium chelates per patient was 34 +/- 19 mL). Gadolinium chelates were the sole contrast agent in 17 examinations, were used in conjunction with carbon dioxide (CO2) in 8 studies, (mean 212 +/- 226 mL), and were combined with the restricted use of nonionic iodinated contrast (mean 12.8 +/- 4.7 mL) in 6 examinations. We carried out 15 diagnostic angiographies and 15 percutaneous transluminal angioplasties. RESULTS: Use of gadolinium chelates allowed us to obtain diagnostic angiographic images in all cases. However, the quality of angiograms was inferior compared with that obtained with iodinated contrast agents and superior compared with CO2 as the contrast material. Adverse events were not noted. Mean serum creatinine was 2.6 +/- 1.5 mg/dL before and 2.3 +/- 1.0 mg/dL after DSA. No patient developed contrast-induced nephropathy. CONCLUSIONS: Gadolinium chelates produce an x-ray DSA intermediate in image quality between iodinated contrast and CO2. Digital subtraction angiography with intra-arterial gadolinium chelate administration may offer an alternative to iodinated contrast material in patients with contraindications to iodine.

Aged↗

PubMed2001

Vascular response to gadolinium-containing contrast media in an ex vivo rabbit arterial model.

RATIONALE AND OBJECTIVES: To assess the influence of gadolinium-containing magnetic resonance contrast agents on contractility of the arterial vessel wall. METHODS: Bilateral segments of rabbit carotid arteries were mounted in flow chambers, surrounded by aerated (95% O2, 5% CO2) Krebs' solution, and perfused at a constant rate by separated and aerated Krebs' solution. Therefore, changes in pressure of the circulating Krebs' solution indicated alterations of vessel wall contractility. Viability of the artery was tested by 124 mmol/L KCl, 3 x 10-5 mol/L phenylephrine, and 10-5 mol/L acetylcholine. After a washout phase, gadopentate (n = 10) or gadoteridol (n = 10) was added to the perfusate of one carotid artery in increments of 0.1, 0.3, and 0.6 mmol/L. Concentrations up to 0.9 mmol/L and 1.2 mmol/L were tested, respectively. The contralateral artery served as a control. To assess potential relaxing effects of the media, vessels were brought into a contracted status with 3 x 10-5 mol/L phenylephrine and then received gadolinium chelates. RESULTS: Potassium chloride and phenylephrine increased and acetylcholine decreased the pressure, indicating vasoconstriction and vasodilatation, respectively. After gadopentate and gadoteridol infusion, no statistically significant pressure changes could be detected, ruling out any vasoconstrictor or vasodilator effect. CONCLUSIONS: Gadopentetate and gadoteridol in doses of up to 1.2 mmol/L did not alter vessel wall tone. The impact of contrast media on blood pressure, as has been shown in some clinical trials, probably is not due to direct changes in arterial wall tone.

Animals↗

PubMed2001

Normalized quantification by real-time PCR of Epstein-Barr virus load in patients at risk for posttransplant lymphoproliferative disorders.

The load of Epstein-Barr virus (EBV) in peripheral blood mononuclear cells of transplant recipients represents a predictive parameter for posttransplant lymphoproliferative disorders (PTLD). The aim of our work was to develop a rapid and reliable PCR protocol for the quantification of cell-associated EBV DNA in transplant recipients. In contrast to previous studies, a protocol that facilitated quantification independent of photometric nucleic acid analysis was established. We took advantage of the real-time PCR technology which allows for single-tube coamplification of EBV and genomic C-reactive protein (CRP) DNA. EBV copy numbers were normalized by division by the amount of CRP DNA, with the quotient representing the actual amount of amplifiable genomic DNA per reaction. Coamplification of CRP DNA did not result in a diminished detection limit for EBV. By using the protocol without normalization, EBV copy numbers in 4 out of 10 PTLD patients were within the normal range determined with data for 114 transplant recipients that served as controls. After normalization, however, all of the PTLD patients had a higher viral load than the control population, indicating an increased sensitivity of the assay. Moreover, EBV copy numbers obtained for one patient by conventional quantification and suggestive of relapsing PTLD were within normal range after normalization. We conclude that normalization of PCR signals to coamplified genomic DNA allows a more accurate quantification of cell-bound EBV.

Calibration↗