[Suitability of modulated transillumination as coagulation control for laser-induced thermotherapy].
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Breast Neoplasms↗
Biomedical subjects
G Müller
Publications and source records attributed to G Müller.
COMP (cartilage oligomeric matrix protein) is synthesized in ligament, tendon, meniscus, and articular cartilage.
The presence of cartilage oligomeric matrix protein (COMP) in extracts of ligament, tendon, meniscus, and canine articular cartilage was demonstrated by Western blot analysis using anti-dog COMP antibody. When the tissues were cultured in the presence of [35-S]methionine/cysteine, metabolically labeled COMP was purified from the culture media and from tissue extracts by DEAE-cellulose gel chromatography. SDS-Polyacrylamide gel electrophoresis (SDS-PAGE) followed by autoradiography and immunoblotting under reducing and non-reducing conditions revealed that COMP is synthesized by the cells of these connective tissues. Increased levels of COMP in samples of both synovial fluid and serum of patients with various joint diseases may not only be derived from cartilage but also from ligaments and tendons. COMP is not a highly tissue-specific cartilage molecule.
Animals↗
Behavioural studies with a highly emotional mouse strain newly bred in EGIS Pharmaceuticals Ltd.
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Animals↗
Convergence and divergence of the signaling pathways for insulin and phosphoinositolglycans.
Phosphoinositolglycan molecules isolated from insulin-sensitive mammalian tissues have been demonstrated in numerous in vitro studies to exert partial insulin-mimetic activity on glucose and lipid metabolism in insulin-sensitive cells. However, their ill-defined structures, heterogeneous nature, and limited availability have prohibited the analysis of the underlying molecular mechanism. Phosphoinositolglycan-peptide (PIG-P) of defined and homogeneous structure prepared in large scale from the core glycan of a glycosyl-phosphatidylinositol-anchored membrane protein from Saccharomyces cerevisiae has recently been shown to stimulate glucose transport as well as a number of glucose-metabolizing enzymes and pathways to up to 90% (at 2 to 10 microns) of the maximal insulin effect in isolated rat adipocytes, cardiomyocytes, and diaphragms (G. Müller et al., 1997, Endocrinology 138: 3459-3476). Consequently, we used this PIG-P for the present study in which we compare its intracellular signaling with that of insulin. The activation of glucose transport by both PIG-P and insulin in isolated rat adipocytes and diaphragms was found to require stimulation of phosphatidylinositol (PI) 3-kinase but to be independent of functional p70S6kinase and mitogen-activated protein kinase. The increase in glycerol-3-phosphate acyltransferase activity in rat adipocytes in response to PIG-P and insulin was dependent on both PI 3-kinase and p70S6kinase. This suggest that the signaling pathways for PIG-P and insulin to glucose transport and metabolism converage at the level of PI 3-kinase. A component of the PIG-P signaling pathway located up-stream of PI 3-kinase was identified by desensitization of isolated rat adipocytes for PIG-P action by combined treatment with trypsin and NaCl under conditions that preserved cell viability and the insulin-mimetic activity of sodium vanadate but completely blunted the insulin response. Incubation of the cells with either trypsin or NaCl alone was ineffective. The desensitized adipocytes were reconstituted for stimulation of lipogenesis by PIG-P by addition of the concentrated trypsin/salt extract. The reconstituted adipocytes exhibited 65-75% of the maximal PIG-P response and similar EC50 values for PIG-P (2 to 5 microns) compared with control cells. A proteinaceous N-ethylmaleimide (NEM)-sensitive component contained in the trypsin/salt extract was demonstrated to bind in a functional manner to the adipocyte plasma membrane of desensitized adipocytes via bipolar interactions. An excess of trypsin/salt extract inhibited PIG-P action in untreated adipocytes in a competitive fashion compatible with a receptor function for PIG-P of this protein. The presence of the putative PIG-P receptor protein in detergent-insoluble complexes prepared from isolated rat adipocytes suggests that caveolae/detergent-insoluble complexes of the plasma membrane may play a role in insulin-mimetic signaling by PIG-P. Furthermore, treatment of isolated rat diaphragms and adipocytes with PIG-P as well as with other agents exerting partially insulin-mimetic activity, such as PI-specific phospholipase C (PLC) and the sulfonylurea glimepiride, triggered tyrosine phosphorylation of the caveolar marker protein caveolin, which was apparently correlated with stimulation of lipogenesis. Strikingly, in adipocytes subjected to combined trypsin/salt treatment, PIG-P, PI-specific PLC, and glimepiride failed completely to provoke insulin-mimetic effects. A working model is presented for a signaling pathway in insulin-sensitive cells used by PIG(-P) molecules which involves GPI structures, the trypsin/salt- and NEM-sensitive receptor protein for PIG-P, and additional proteins located in caveolae/detergent-insoluble complexes.
Adipocytes↗
[The infected arterial stent].
Vascular infections after percutaneous endovascular procedures are rare. We report a case of bacterial arteritis following PTA and stent implantation into an iliac artery. It was complicated by septic embolization, ipsilateral empyema of the knee joint and formation of an infected false aneurysm. Contamination of the stent with Staphylococcus aureus is likely to be the cause. The treatment included resection of the infected arterial segment, removal of the stent, and autologous reconstruction.
Aged↗
[Medical guidelines for diabetes mellitus in Saxony. An instrument for interdisciplinary quality management for optimizing patient care].
Patients with diabetes still have a life expectancy of 5-10 years less and a markedly reduced quality of life than non-diabetic persons. Concepts, models, and contracts aiming at an efficient co-operative care for chronically ill patients have been developed in the new German states to overcome shortage of care. The dual care of motivated diabetic patients by family physicians and experts for metabolic diseases has proven to be efficient both in pilot studies as well as in country-wide investigations. A representative commission for diabetes has developed guidelines for such a structure of dual care. Design and content of these regional developed guidelines about an cooperative evidence based care for diabetic patients fulfills the criteria suggested by international bodies of experts and the medical society for quality assurance. The Saxonian guidelines for diabetes have been successfully implemented step by step in medical offices and hospitals. We are sure that the further implementation of the shared care system diabetes will further improve quality of care.
Adolescent↗
[Functional and oncological results of sphincter preserving rectal resection].
Most of the patients with a carcinoma of the middle and distal third of the rectum can now be operated on with a low anerior resection in consideration of all aspects of cancer surgery. Our experience with 59 resections with coloanal or low colorectal anastomosis was reviewed. The mean distance of the distal edge of the tumor to the L. anocutanea was 5.7 +/- 1.9 cm. Within the first 30 days the postoperative mortality rate was 3.4% (2/59). The most common postoperative complication was urinary retention, which affected 13.5%. The insufficiency rate of the anastomosis was 13.5%. Fecal continence was complete in 85% of the patients: we observed minor leaks in 6% and major leaks in 9%. Local recurrence occurred in 2 cases (3.8%), metastasis was noted in 6 cases (11.3%). Sphincter-preserving rectal resection is in our opinion an excellent treatment for low rectal cancer.
Adult↗
Early changes in the phenotypic composition of lymphocytes in the bronchoalveolar lavage of pigs after aerogenic immunization with Pasteurella multocida aerosols.
The phenotypic composition of bronchoalveolar lymphocytes (BALL) of healthy untreated pigs and of pigs immunized via aerosol with a live Pasteurella multocida mutant was measured cytofluorometrically in comparison to blood lymphocytes (PBL). Cells were analyzed using monoclonal antibodies against porcine IgM, IgA, IgG and SWC3 in single-colour fluorescence and the following antibody combinations for two-colour fluorescence: CD2/SWC1, SWC1/CD25 and CD4/CD8. In nonimmunized pigs, differences between lymphocyte subsets derived from blood and lung were obvious. The numbers of CD2-SWC1+ T-cells, CD25+ activated lymphocytes and IgG+ cells were significantly higher in the bronchoalveolar compartment. Aerosol immunization with P. multocida caused only insignificant changes in the phenotypic composition of PBL whereas the composition of lung-derived lymphocytes changed markedly. The percentage of CD2-SWC1+ lymphocytes and of CD25+ cells coexpressing the SWC1 antigen in BALL increased up to 10 days after aerosol administration, whereas the percentage of all Ig+ cells decreased. These data reflect an early cellular reaction to an aerogenic immunization with a P. multocida aerosol, characterized by an increase in CD2+ T-cells and a T-cell activation.
Aerosols↗
Analysis of lipid metabolism in adipocytes using a fluorescent fatty acid derivative. I. Insulin stimulation of lipogenesis.
Stimulation of lipid synthesis (lipogenesis) is one of the most pronounced metabolic actions of insulin. Here we demonstrate insulin-stimulated lipogenesis in isolated rat adipocytes using a fatty acid derivative which carries a fluorophore. Three major fluorescent lipid products (lipids 1, 2, 3) are generated as revealed by TLC analysis and subsequent fluorescent scanning or imaging. Lipolytic digestion and labeling studies suggest monoacylglycerol-3-phosphate and diacylglycerol (-3-phosphate) structures harboring a single fluorescent fatty acyl residue each for lipids 1 and 3 (2), respectively. Fluorescent triglycerides are not generated. Assaying acylation with isolated microsomes using the purified lipids 1 and 3 indicates that incorporation of one fluorescent fatty acyl residue into glycerol(-3-phosphate) interferes with subsequent esterification. Pretreatment of the adipocytes with insulin significantly stimulates synthesis of lipids 1 and 2, only. The insulin concentration-response relationship (EC50 = 0.5 nM) and the maximal insulin response for synthesis of lipid 1 (stimulation factor = 14- to 20-fold at low glucose and 3- to 7-fold at high glucose) are comparable with those for incorporation of [3-3H]glucose into total adipocyte lipids. Thus this fluorescence-based assay may be useful for studying insulin action and lipogenesis.
Adipocytes↗
Production of IL-18 (IFN-gamma-inducing factor) messenger RNA and functional protein by murine keratinocytes.
Recently, the novel cytokine IL-18 (IFN-gamma-inducing factor) has been described as a growth and differentiation factor for Th1 cells. Epidermal keratinocytes (KC) are known to direct T cell education by production of cytokines. Therefore, expression of IL-18 was sought in KC. Epidermal RNA was analyzed following stimulation with contact sensitizers or controls for IL-18 mRNA expression by semiquantitative reverse transcription-PCR. Constitutive expression of IL-18 mRNA was low in untreated epidermal cells (EC), but early up-regulation of IL-18 mRNA signals was detected following application of a contact allergen in vivo. The peak strength of IL-18 signals was observed within 4 to 6 h following stimulation with an allergen. Application of an irritant (benzalconiumchloride) or solvents did not result in increased signal strength. To determine the cellular origin of IL-18 mRNA in EC, depletion experiments were performed. IL-18 signals were not affected by depletion with anti-CD3 (T cells) or anti-MHC class II mAb-coupled beads identifying KC as a major source of IL-18. These results were confirmed by analysis of mRNA derived from the KC cell line PAM 212. Strong IL-18 signals could be detected by reverse transcription-PCR. To delineate whether IL-18 protein was produced by EC/KC, a sandwich ELISA was used to assay for IL-18 production. Supernatants from allergen-stimulated EC and KC showed production of IL-18 protein. To confirm that IL-18 protein was functional, EC or KC supernatants were tested for their ability to induce IFN-gamma production. Significant amounts of IFN-gamma were detected in supernatants of allergen-treated cells. In aggregate, our data indicate that murine KC are a source of both IL-18 mRNA and functional protein.
Animals↗
Leptin impairs metabolic actions of insulin in isolated rat adipocytes.
Leptin is an adipocyte hormone involved in the regulation of energy homeostasis. Generally accepted biological effects of leptin are inhibition of food intake and stimulation of metabolic rate in ob/ob mice that are defective in the leptin gene. In contrast to these centrally mediated effects of leptin, we are reporting here on leptin effects on isolated rat adipocytes. Leptin impairs several metabolic actions of insulin, i.e. stimulation of glucose transport, glycogen synthase, lipogenesis, inhibition of isoproterenol-induced lipolysis, and protein kinase A activation, as well as stimulation of protein synthesis. Insulin effects were reduced by leptin (2 nM) with a half-life of about 8 h. At low leptin concentrations (<1 nM), the insulin sensitivity was reduced leading to a shift to the right in the dose-response curve. At higher concentrations the responsiveness was diminished, resulting in nearly complete inhibition of insulin effects at >30 nM leptin. The IC50 value of leptin was 3.1 +/- 1 nM after 15 h of preincubation of adipocytes in primary culture. The natural splice variant des-Gln49-leptin exhibited a significantly lower potency. Adipocytes regained full insulin sensitivity within a few hours after leptin removal. The stimulation of glucose transport by vanadate was not affected by leptin. These data show specific and potent impairment of insulin action by leptin in the physiological concentration range of both leptin and insulin, which may be related to the pathophysiology of insulin resistance in both non-insulin-dependent diabetes mellitus and obesity.
Adipocytes↗
Induction of IL-15 messenger RNA and protein in human blood-derived dendritic cells: a role for IL-15 in attraction of T cells.
IL-15 is a pleiotropic cytokine with IL-2-like functions. As IL-15 was shown to be mitogenic for T cells, we wondered whether human blood-derived dendritic cells (DC), as the primary stimulators of T cell responses, are able to produce IL-15. To test our hypothesis, DC were grown under serum-free conditions from human peripheral blood using granulocyte-macrophage CSF and IL-4. Cultures were assayed for IL-15 mRNA production at various times by semiquantitative reverse transcription-PCR. Low baseline signals were detected from days 0 to 5 of culture. A significant increase was detected from days 5 to 9 of the culture. When DC were further enriched by immunomagnetic beads to >98% purity as determined by CD83 staining, IL-15 mRNA signals were exclusively found in the CD83+ fraction. This increase in mRNA signals was paralleled by IL-15 protein release from days 9 to 12 as detected by CTLL-2 assay and ELISA. In addition, protein levels were increased >10-fold by adding paramagnetic beads to the cultures, thereby inducing phagocytic activity. Furthermore, DC supernatants were tested for chemokinetic and chemotactic activities for T cells in a checkerboard filter assay. It was shown that supernatants express chemokinetic and chemotactic activity for T cells. This activity was blocked almost completely by addition of an anti-IL-15 mAb. Our data show that human blood DC contain IL-15 mRNA and produce functional protein that is induced in culture. Protein release is triggered by phagocytic activity. Furthermore, DC-derived IL-15 has chemotactic and chemokinetic activities for T cells, suggesting a role for IL-15 as an attractant of T cells during the initial DC/T cell interaction.
Cells, Cultured↗
Enhancement of TNF receptor p60-mediated cytotoxicity by TNF receptor p80: requirement of the TNF receptor-associated factor-2 binding site.
TNFR p60 (TNFR60) is the main mediator of TNF-induced apoptosis, although in some cells TNFR80 is also involved. TNFR80-dependent induction or enhancement of cytotoxicity has been explained by intracellular signaling, "ligand passing," or induction of endogenous TNF. Using HeLa transfectants expressing wild-type TNFR80 and deletion mutants derived from them, we have investigated the mechanism of TNFR80-mediated cytotoxicity. TNFR80 induces no cytotoxicity on its own, but is functional in these transfectants, as selective stimulation activates nuclear factor-kappaB (NF-kappaB) and induces NF-kappaB-dependent cellular responses (IL-6 and manganese superoxide dismutase). TNFR60-induced cytotoxicity, however, is enhanced about 1000-fold by costimulation of TNFR80, whereas only additive responses are observed with regard to NF-kappaB-dependent responses. Ligand passing is not critically involved, because a similar potentiation of TNFR60-mediated cytotoxicity was observed when agonistic Abs were used for stimulation of both receptors. In addition, in HeLa cells overexpressing a truncated form of TNFR80 lacking the cytoplasmic domain, no TNFR80-dependent potentiation of TNFR60-mediated cytotoxicity was detectable, emphasizing that intracellular signaling of TNFR80 is required for synergistic activity. The involvement of endogenously produced TNF can be ruled out by the use of TNF-neutralizing Abs. The ability of TNFR80 to cooperate with TNFR60 could be mapped to the binding site for the TNF receptor-associated factor-2. These results are in agreement with a differential cooperation of both TNFR; an additive effect is obtained in those responses that are initiated by both receptors via identical pathways, i.e., activation of NF-kappaB, whereas induction of cytotoxicity is most likely mediated by distinct signaling pathways, allowing positive cooperativity.
Binding Sites↗
Enterovirus heart disease of adults: a persistent, limited organ infection in the presence of neutralizing antibodies.
Detection of enterovirus RNA in endomyocardial biopsies (EMB) by reverse transcription/polymerase chain reaction (RT-PCR) is currently the preferred diagnostic procedure in suspected enterovirus heart disease (EHD), which can present clinically as myocarditis, dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC). EMB and peripheral blood mononuclear cells (PBMC) of 44 patients with suspected EHD were examined by nested RT-PCR to investigate whether the myocardial enterovirus infection is limited to the heart or is generalized. Enterovirus RNA was detected in EMB, but not in PBMC, of 8 patients (3 of these suffered from ARVC), whereas EMB of 16 controls and PBMC of 45 controls were negative. In addition, enterovirus RNA was demonstrated in PBMC, but not in EMB, of a single patient with suspected EHD. A high sequence homology of the amplicons to coxsackievirus B3 was demonstrated in 7 patients, and to coxsackievirus B2 in two patients. In order to evaluate whether the myocardial enterovirus infection was acute or persistent, neutralization and complement fixation tests were performed for antibodies against the serotypes indicated by the nucleic acid sequences. Neutralizing antibodies were detected in the sera of all 9 patients, but complement fixing antibodies were demonstrated only in one EHD patient and in the patient positive for enterovirus RNA in PBMC. In conclusion, the molecular and serological data demonstrate that CVB3 predominates as cardiotropic enterovirus, and that the enterovirus replication is limited to the heart in EHD. Serological results support the hypothesis of myocardial enterovirus RNA persistence in spite of neutralizing antibodies.
Adult↗
Mapping of ligand binding sites of the cholecystokinin-B/gastrin receptor with lipo-gastrin peptides and molecular modeling.
Double-tailed lipo-tetragastrin derivatives of increasing fatty acid chain length were used to identify the minimum size of the fatty acid moieties (> or = C10) that restricts the access to the CCK-B/gastrin (CCK: cholecystokinin) receptor via a membrane-bound pathway. Then dimyristoyl-mercaptoglycerol/maleoyl-gastrin adducts of increasing peptide chain length were synthesized to define the minimal peptide size required for receptor binding affinities comparable, to those of underivatized gastrin peptides despite anchorage of the lipid tails in the membrane bilayer. The experimental results indicated that most of the little-gastrin sequence, i.e., 2-17, is needed for optimal interaction of the molecule with the binding cleft of the receptor. From these data experimentally based restraints could be derived for docking of lipo-gastrin onto a CCK-B/gastrin receptor model applying molecular dynamics simulations and energy minimizations. In the receptor-bound state some of the secondary structure elements of gastrin as determined by nmr analysis of gastrin-peptides in low dielectric constant media are retained. The N-terminal gastrin portion interacts in a more or less extended conformation with the receptor surface, and upon a sharp kink at the Ala-Tyr dipeptide portion the C-terminal pentapeptide amide part inserts deeply into the helix bundle. Besides Arg-57 on top of helix 1 of the receptor, for which no potential interaction with the ligand could be detected, the other amino acid residues identified by mutagenesis studies as involved in gastrin recognition were found to interact with the C-terminal portion of gastrin. Even taking into account the strong limitations of such a model system, it represents an interesting tool for rationalizing the experimental results of the extensive structure-function studies performed previously on gastrin and to delineate more precisely the putative ligand binding site on the extracellular face of the receptor.
Amino Acid Sequence↗
Pro-inflammatory cytokines and prostaglandins induce maturation of potent immunostimulatory dendritic cells under fetal calf serum-free conditions.
Culture conditions for human dendritic cells (DC) have been developed by several laboratories. Most of these culture methods, however, have used conditions involving fetal calf serum (FCS) to generate DC in the presence of granulocyte-macrophage colony-stimulating factor and interleukin (IL)-4. Recently, alternative culture conditions have been described using an additional stimulation with monocyte-conditioned medium (MCM) and FCS-free media to generate DC. As MCM is a rather undefined cocktail, the yield and quality of DC generated by these cultures varies substantially. We report that a defined cocktail of tumor necrosis factor (TNF)-alpha, IL-1beta and IL-6 equals MCM in its potency to generate DC. Addition of prostaglandin (PG)E2 to the cytokine cocktail further enhanced the yield, maturation, migratory and immunostimulatory capacity of the DC generated. More importantly, culture conditions also influenced the outcome of the T cell response induced. DC cultured with TNF-alpha/IL-1/IL-6 or MCM alone induced CD4+ T cells that release intermediate levels of interferon (IFN)-gamma and no IL-4 or IL-10. Production of IFN-gamma was significantly induced by addition of PGE2, while no effect on production of IL-4 or IL-10 was observed. Even more striking differences were observed for CD8+ T cells. While MCM conditions only induced IFN-gamma(low), IL-4(neg) cells, TNF-alpha/IL-1/IL-6 promoted growth of IFN-gamma(intermediate), IL-4(neg) CD8+ T cells. Addition of PGE2 again only further polarized this pattern enhancing IFN-gamma production by alloreactive CD8+ T cells in both cultures without inducing type 2 cytokines. Taken together, the data indicate that the defined cocktail TNF-alpha/IL-1/IL-6 can substitute for MCM and that addition of PGE2 further enhances the yield and quality of DC generated. TNF-alpha/IL-1, IL-6 + PGE2-cultured DC seem to be optimal for generation of IFN-gamma-producing CD4/CD8+ T cells.
Cell Differentiation↗
[The locoregional recurrence of rectal carcinoma. A computed tomographic analysis and a target volume concept for adjuvant radiotherapy].
BACKGROUND: In the adjuvant postoperative radiotherapy of rectal carcinoma the knowledge of the predominant areas of recurrences is of major importance for the definition of the target volume. We analysed the pattern and locations of tumor recurrences in the CT scans of 155 patients and correlated the findings with the primary tumor location (above and below the peritoneal duplication) and the operating method (abdominoperineal extirpation, anterior resection. Hartmann procedure). PATIENTS AND METHOD: Hundred and fifty-five patients with the diagnosis of rectal carcinoma recurrences were treated in our institution between 1980 and 1995. To determine the extension of the recurrent tumor within the pelvic levels (presacral levels S1-S5, precoccygeal, pelvic floor level and perineal level) and the tumor infiltration of pelvic organs and muscles we analysed the pretherapeutic CT images. The lymph node recurrences were classified as: pararectal, presacral, iliac internal, iliac external, iliac communis and para-aortal recurrences. RESULTS: Sixty-one percent of the patients with rectum extirpation and 66% with anterior resection showed a combined local and nodal recurrence. Isolated lymph node recurrences were rare (4% and 5%) (Tables 2 and 3). The local recurrence was mostly situated in the presacral pelvis, predominantly there was an infiltration of the presacral space at the level of S4, S5 and os coccygis regardless of the operating method and the primary tumor location (Figure 1). The anastomosis was involved in the tumor recurrence in 93% of the anteriorly resected patients (Table 3). In 9 out of 96 patients after rectum extirpation the pelvic region caudal of the tip of the coccyx was the origin of the recurrent tumor (Table 2, Figure 2). Primarily all 9 patients had a deep-seated carcinoma (< 6 cm ab ano). Only 2 patients showed an isolated perineal recurrence after rectum extirpation (Table 2. Figure 2). Two thirds of the deep-seated tumors showed a vaginal involvement (Figures 3 and 4). The incidence of iliac internal and presacral nodal recurrence was 47 to 59% (Figures 3 and 4). The incidence of iliac external lymph node recurrences was 7% after rectum extirpation and 2% after anterior resection/Hartmann procedure. CONCLUSION: Our data demonstrate that 2/3 of the patients with tumor-bed recurrences also show lymph node recurrences predominantly in the iliac internal and presacral groups. This has to be considered in the definition of the boost target volume. The target volume must also include the dorsal wall of the urogenital organs. A ventral extension of target volume up to iliac external lymph nodes is not necessary.
Adenocarcinoma↗
[Thermometry by measuring the chemical shift of lanthanide complex].
BACKGROUND: In the long-term, non-invasive thermometry is vital for the continued clinical and technological development of regional hyperthermia. In magnetic resonance tomography. T1 relaxation time, diffusion and proton resonance frequency are used to measure temperature distributions. When used clinically in the pelvic region, all of these methods are plagued with errors and artefacts on account of the tissue relationships, tissue changes under hyperthermia, physiological and stochastic movements, inhomogeneities, drift phenomena and instabilities. MATERIAL AND METHOD: We tested the relationship between the temperature and the chemical shift of a methyl group of a lanthanide complex with central atom praseodymium (Pr-MOE-DO3A. Schering AG). To do this we used cylindrical phantoms containing a 5-mmol-solution of this temperature-sensitive substance. High resolution spectra and relaxation times were determined in a Bruker AMX at 11.5 T. A calibration curve was then recorded by a Siemens Magnetom SP63 at 1.5 T. Local temperature distributions were determined using the chemical shift imaging method, with a matrix size of 16 x 8 and a narrow-band excitation pulse. The temperature distribution was created using a Nd:YAG laser applicator. RESULTS: At a distance of -25.7 ppm from the water line, we found a singlet line with a temperature-dependent chemical shift of 0.13 ppm/C. In the phantom experiment we found that the chemical shift had a linear relationship with a gradient independent of the surroundings, and a temperature resolution of +/-0.6 degree C. With a concentration of 1 mmol/l, a matrix size of 8 x 8 and a measurement period of 5 s per acquisition, phantom measurements using the CSI method produced a signal to noise ratio of 3.5 per acquisition, i.e a measurement period of 10 to 20 s per spectrum. CONCLUSIONS: Our in vitro data show that spectroscopic temperature measurement using a temperature-sensitive praseodymium complex with a therapeutically practical concentration of 1 mmol/l already appears to be suitable for clinical use Compared with the methods tested so far (T1, diffusion, proton resonance), this method has the special advantage of not being very susceptible to artefacts. The competing methods of non-invasive thermometry using magnetic resonance tomography/spectroscopy will be investigated next.
Artifacts↗