[Quantitation of glutamate in the brain by using MR proton spectroscopy at 1.5 T and 3 T]. / Quantitative Bestimmung von Glutamat im Hirn mithilfe der MR-Protonenspektroskopie bei 1,5 T und 3 T.

PURPOSE: The influence of different magnetic field strengths on the quantification of glutamate was experimentally investigated by means of IN VITRO and IN VIVO (1)H-MR spectroscopic measurements at 1.5 T and 3 T. MATERIALS AND METHODS: In vitro (1)H-MR measurements of aqueous solutions of NAA, glutamate, glutamine and GABA were performed on two clinical MR scanners at 1.5 T and 3 T using a single voxel PRESS sequence (TR/TE = 10 000 / 30 ms). IN VITRO brain measurements were also performed at both field strengths using a PRESS 2D- (1)H-CSI-sequence (TR/TE = 5000 / 30 ms) in 6 volunteers. Spectra at 1.5 T and 3 T were compared with respect to the overlap of the single compound spectra and the deviations between estimated and nominally adjusted concentrations. In vivo spectra at both field strengths were compared with respect to SNR (Glu), line width and Cramer-Rao values of the estimated glutamate intensities by using the LCModel. For the thalamus, insular and parietal cortex mean Glu/tCr ratios were estimated and compared between 1.5 T and 3 T as well as with corresponding values in the literature. RESULTS: In general, an improved separation of signal maxima was observed in the IN VITRO spectra at 3 T. Except for GABA, all IN VITRO concentrations estimated at 3 T revealed lower deviations from their adjusted nominal concentration compared to 1.5 T: NAA (1.5 T: -5.5 %, 3 T: 0.7 %), glutamate (1.5 T: -18.1 %, 3 T: 12.3 %), glutamine (1.5 T: 44.8 %, 3 T: 9.2 %), GABA (1.5 T: - 24.8 %, 3 T: 33.8 %). The SNR of IN VIVO spectra at 3 T was nearly doubled compared to 1.5 T. The mean number of voxels with %SD (Glu)< 20 was distinctly lower at 1.5 T (53 %) than at 3 T (80 %). Estimated Glu/tCr ratios for thalamus, insular and parietal cortex lay in the upper range of the literature values. CONCLUSION: The results indicate that the advantageous distribution of signal maxima at 3 T allows an improved separation of the individual spectra. Both the higher initial magnetization at 3 T and the improved sensitivity of the phased array matrix coil used in the 3 T study result in an increased SNR, which leads to better reliability of the individual detection as well as a more accurate quantification of glutamate.

[Magnetically based enhancement of nanoparticle uptake in tumor cells: combination of magnetically induced cell labeling and magnetic heating]. / Magnetisch basierte Steigerung der Nanopartikelaufnahme in Tumorzellen: Kombination von magnetisch induzierter Zellmarkierung und magnetischer Wärmebehandlung.

PURPOSE: Magnetic nanoparticles (MNP) are known to be versatile tools in diagnostic and interventional radiology. The goal of the present study was to assess whether MNP can be selectively accumulated on human adenocarcinoma cells in vitro using an external magnetic field (magnetically induced cell labeling) and whether these labeled tumor cells can then be destroyed after being exposed to an alternating magnetic field (magnetically induced heating). In this context, a long-term goal is to combine these two developing methods to achieve an additive effect in tumor therapy. MATERIALS AND METHODS: BT-474 cells were incubated until confluence. Magnetic nanoparticles (0.32 mg Fe/ml culture medium) were then added and the flask was exposed to an external magnetic field gradient (magnetically induced cell labeling, 56 or 83 mT magnets) for 24 hours in order to label the tumor cells with nanoparticles. Cells without both MNP and magnetic labeling as well as cells with MNP incubation but without magnetic labeling served as controls. After MNP incubation, the magnetically labeled cells (5 x 10 (7) cells/ml) were exposed to an alternating magnetic field for 5.45 minutes (frequency 400 kHz, amplitude 24.6 kA/m). The combination effect of both magnetic labeling and magnetic heating was assessed by determining the temperature increase. The amount of MNP accumulated within the cells was determined by measuring the iron content via atomic absorption spectrometry. For statistical analysis mean values and standard deviations of temperature increases and iron contents were calculated and the differences were analyzed using the Student's t-test. RESULTS: A significant temperature increase (p < 0.01) during magnetic heating of 41.76 +/- 4.60 K was detected after magnetic labeling of the cells (5 x 10 (7) cells/ml, 83 mT) incubated with MNP. In comparison, the cells incubated with MNP but without magnetic labeling revealed a temperature increase of 32.03 +/- 3.33 K, naked cells of only 2.69 +/- 0.34 K. CONCLUSION: The results demonstrated the magnetically based enhancement of cellular uptake of nanoparticles by tumor cells, resulting in the intensification of the generated temperature increase during magnetic heating. Consequently, magnetic nanoparticles are shown to be valuable tools for the combination of magnetically based therapy modalities.

Digital X-ray radiogrammetry combined with semiautomated analysis of joint space widths as a new diagnostic approach in rheumatoid arthritis: a cross-sectional and longitudinal study.

OBJECTIVE: To evaluate digital x-ray radiogrammetry (DXR) and the Radiogrammetry Kit program as new diagnostic tools for quantifying disease-related periarticular osteoporosis and for measuring joint space narrowing according to the severity and duration of rheumatoid arthritis (RA). METHODS: Using DXR, we performed computerized calculations of bone mineral density (BMD) and the metacarpal index (MCI) in 258 patients with active RA. Using the Radiogrammetry Kit program, we also performed semiautomated measurements of joint space width (JSW) at the second through the fifth metacarpophalangeal (MCP) joints in these patients. RESULTS: All correlations between the different parameters of both techniques (BMD and the MCI as measured by DXR and MCP JSW as measured by the Radiogrammetry Kit) were significant (0.36 < or = R < or = 0.63; P < 0.01). As expected, a significant negative association was shown between the different MCP JSW results and the results of all scoring methods (-0.67 < or = R < or = -0.29). The BMD and the MCI measured by DXR both decreased significantly between Steinbrocker stage I and stage IV (by 32.7% and 36.6%, respectively; both P < 0.01). Reductions in the overall (mean) MCP JSW varied from 35.3% (Larsen score) to 52.9% (Steinbrocker stage). Over a period of 6 years, we observed relative decreases in BMD and the MCI as measured by DXR (32.1% and 33.3%, respectively), as well as in the overall (mean) MCP JSW (23.5%), and these were pronounced in early RA (duration <1 year). In addition, excellent reproducibility of DXR and Radiogrammetry Kit parameters was verified (coefficients of variation <1%). CONCLUSION: DXR with the integrated Radiogrammetry Kit program could be a promising, widely available diagnostic tool for supplementing the different RA scoring methods with quantitative data, thus allowing an earlier and improved diagnosis of RA and more precision in determining disease progression.

[Magnetic thermotherapy of breast tumors: an experimental therapeutic approach]. / Magnetische Thermotherapie von Tumoren der Brust: ein experimenteller Therapieansatz.

The therapeutic strategy for breast cancer is changing, especially for early tumor stages with good prognosis. One potential minimally invasive therapy modality consists in the accumulation of a well-tolerated magnetic material (iron oxides, particularly magnetite) in the target tissue. By applying an alternating magnetic field, energy is selectively absorbed and induces harmful heating of the tumor. The present review deals with the essential conditions and parameters as studied in vitro and in vivo in animal experiments. Extrapolations to the clinical situation are discussed, in particular, the heating potential of the magnetic material, the selection of the magnetic field parameters, the occurrence of eddy currents, the generation of localized heating spots and the expected temperature rises and their effects on the tumor area.

Use of magnetic nanoparticle heating in the treatment of breast cancer.

Magnetic nanoparticles are promising tools for the minimal invasive elimination of small tumours in the breast using magnetically-induced heating. The approach complies with the increasing demand for breast conserving therapies and has the advantage of offering a selective and refined tuning of the degree of energy deposition allowing an adequate temperature control at the target. The biophysical basis of the approach, the magnetic and structural properties of magnetic nanoparticles are reviewed. Results with model targets and in vivo experiments in laboratory animals are reported.

Simultaneous surface electromyography (SEMG) and 31P-MR spectroscopy measurements of the lumbar back muscle during isometric exercise.

The aim of this study was to demonstrate the feasibility of simultaneous surface electromyography (SEMG) and 31P-MR spectroscopy (31P-MRS) measurements on the back muscle of volunteers during the performance of an isometric exercise. Six volunteers (three male, three female) performed a modified Biering-Sörensen test inside a 1.5 T MR scanner while simultaneously recording SEMG signals. A surface coil was used for 31P-MRS with a CSI sequence. Spectra were collected with a voxel resolution of 40 mm x 40 mm x 100 mm and a temporal resolution of 30 s during periods of rest, sustained muscle contraction and recovery. The duration of muscle contraction was 150 s. SEMG analysis yielded a decrease of the mean SEMG frequency of approximately 20%. The SEMG amplitudes were constant or increased up to approximately 150% during exercise. 31P-MRS showed a maximum decrease of the phosphocreatine (PCr) amplitude down to approximately 32% of its initial value. Simultaneously, a doubling of the inorganic phosphate (Pi) signal was observed. The present study demonstrates that simultaneous SEMG and 31P-MRS measurements of the back muscle are feasible during isometric exercises.

31P-MR spectroscopy in children and adolescents with a familial risk of schizophrenia.

Based on a previous report [9] on alterations of membrane phosphorus metabolism in asymptomatic family members of schizophrenic patients, the aim of the present study was to extend and improve the evaluation and data processing of (31)P spectroscopic data obtained from a larger study population by including an analysis of the broad spectral component (BC) of membrane phospholipids (PL). Eighteen children and siblings of patients with schizophrenia and a gender- and age-matched control group of 18 healthy subjects without familial schizophrenia were investigated with phosphorus magnetic resonance spectroscopy ((31)P-MRS) by using image selected in vivo spectroscopy (ISIS) in the dorsolateral prefrontal regions (DLPFR) of the brain. Spectral analysis was performed by using both the full and truncated FID to estimate metabolic peak ratios of different (31)P metabolites and the intensity and linewidth of the broad component. A significantly higher PDE level (p<0.01) and increased linewidth of the PDE components were observed for the high-risk group compared with the control group (p=0.02). No significant differences were observed for PME as well as for other (31)P-metabolites. No differences were observed between the left and right hemispheres for different normalised (31)P-metabolic levels. Decreased intensities (p=0.03) and smaller linewidths (p=0.01) were obtained for the broad component in the high-risk group. Impairments of membrane metabolism that are typical for schizophrenic patients are partially observed in adolescent asymptomatic family members of schizophrenics, including increased levels of low molecular PDE compounds indicating increased membrane degradation processes, no changes for PME, and decreased intensities and linewidths of the BC indicating changes in the composition and fluidity of membrane phospholipids. Despite limitations to completely suppress fast-relaxing components by dismissing initial FID data points, the spectroscopic results indicate additional changes in the membrane metabolism of high-risk subjects beyond changes of synthesis and degradation.

[31P-MR spectroscopy of the brain in patients with anorexia nervosa: characteristic differences in the spectra between patients and healthy control subjects]. / 31P-MRS des Hirns bei Anorexia nervosa: Charakteristische Unterschiede in den Spektren von Patienten und gesunden Vergleichspersonen.

PURPOSE: To investigate whether 31 P-MR spectroscopy can detect reduced concentrations of high-energy phosphates, like PCr and NTP, caused by decreased metabolic activity in the brain of patients with anorexia nervosa (AN) and, furthermore, whether any impairment of the cerebral membrane metabolism can be derived from the spectra. MATERIAL AND METHODS: 10 female patients, age range 12 - 20 years and mean BMI (body mass index) of 14.8 +/- 1.6 kg/m 2, with clinically diagnosed AN (ICD-10, F50.0) and 10 healthy control subjects, age range 12 - 21 years and mean BMI 19.0 +/- 2.1 kg/m 2, without nutritional disturbances: were investigated. 31P-MR spectroscopy was performed with a 1.5 T MRI unit using single volume selection in the frontal/prefrontal region of brain. Relative metabolic concentrations were quantified by normalizing the peak areas of the metabolites with the total area of the complete phosphorous spectrum, P tot, as well as with the peak area of beta-NTP. RESULTS: Significant differences between the two groups were observed for the metabolic ratios PDE/P tot, PDE/beta-NTP and alpha-NTP/P tot which were lower in the patient group except for alpha-NTP/P tot. These ratios also revealed a statistically significant correlation with the BMI (r PDE/Ptot = 0.747, r PDE/beta-NTP = 0.57, r alpha-NTP/Ptot = -0.56; p

Self-incompatibility in ryegrass 12. Genotyping and mapping the S and Z loci of Lolium perenne L.

Perennial ryegrass (Lolium perenne L.) is an outcrossing, wind-pollinated species exhibiting a gametophytic two-locus system of self-incompatibility (S and Z). The two incompatibility loci were genotyped in a cross between a doubled-haploid plant crossed as the female parent with a normal heterozygous plant. The S and Z loci were found to segregate in the expected 1:1 ratio and also segregated independently. The two loci were mapped to linkage groups one and two respectively, in accordance with the Triticeae consensus map. In addition, there were notable associations between the segregation of particular alleles mapping to the S locus region of linkage group 1 and those mapping to the WG889/CDO920 loci region of linkage group 3 which resulted in significant segregation distortions. No such associations were found between the Z locus and this region or any other region of the genome. The L. perenne S and Z loci showed conserved synteny with the equivalent loci in rye (Secale cereale L.).

[In vitro imaging of magnetite particles]. / Bildgebende Darstellung von Magnetiten in vitro.

PURPOSE: To find an optimal imaging modality for the assessment of magnetite agglomerations used as the heating sources during magnetic thermoablation of tumors. METHODS: 1 to 107 mg of coated (starch) magnetite particles were directly administered to an in vitro tumor model (swine lymph nodes) and investigated immediately (radiography) or after being embedded within a 4 % agar-phantom (sonography). T1-weighted MR images (TR = 400 ms, TE = 14 ms) were acquired from lymph nodes containing 0.5 to 25 mg magnetite. RESULTS: All investigated magnetite masses were qualitatively detectable by radiography. Sonographically, only mass agglomerations containing 107 mg magnetite were appropriately discernible. MRT images revealed distinct susceptibility artifacts. CONCLUSIONS: Based on the investigated imaging modalities, radiography is the method of choice for assessment of magnetite agglomerations using relevant dosages for magnetic thermoablation of tumors.

Changes in apoplastic pH and membrane potential in leaves in relation to stomatal responses to CO2, malate, abscisic acid or interruption of water supply.

Low CO2 concentrations open CO2-sensitive stomata whereas elevated CO2 levels close them. This CO2 response is maintained in the dark. To elucidate mechanisms underlying the dark CO2 response we introduced pH- and potential-sensitive dyes into the apoplast of leaves. After mounting excised leaves in a gas-exchange chamber, changes in extracellular proton concentration and transmembrane potential differences as well as transpiration and respiration were simultaneously monitored. Upon an increase in CO2 concentration transient changes in apoplastic pH (occasionally brief acidification, but always followed by alkalinization) and in membrane potential (brief hyperpolarization followed by depolarization) accompanied stomatal closure. Alkalinization and depolarization were also observed when leaves were challenged with abscisic acid or when water flow was interrupted. During stomatal opening in response to CO2-free air the apoplastic pH increased while the membrane potential initially depolarized before it transiently hyperpolarized. To examine whether changes in apoplastic malate concentrations represent a closing signal for stomata, malate was fed into the transpiration stream. Although malate caused apoplastic alkalinization and membrane depolarization reminiscent of the effects observed with CO2 and abscisic acid, this dicarboxylate closed the stomata only partially and less effectively than CO2. Apoplastic alkalinization was also observed and stomata closed partially when KCl was fed to the leaves. Respiration increased on feeding of malate or KCl, or while abscisic acid closed the stomate. From these results we conclude that CO2 signals modulate the activity of plasma-membrane ion channels and of plasmalemma H+-ATPases during changes in stomatal aperture. Responses to potassium malate and KCl are not restricted to guard cells and neighbouring cells.

Electromagnetic heating of breast tumors in interventional radiology: in vitro and in vivo studies in human cadavers and mice.

PURPOSE: To assess relevant parameters for the minimally invasive elimination of breast tumors by using a selective application of magnetite and exposure of the breast to an alternating magnetic field. MATERIALS AND METHODS: The specific absorption rate (SAR) of different magnetite samples was determined calorimetrically. Temperature elevations based on magnetite mass (7-112 mg) and magnetic field amplitude (1.2-6.5 kA/m frequency, 400 kHz) were investigated by using human breast tissue. Parameter combinations (21 mg +/- 9 [SD], 242-second magnetic field exposure, 6.5-kA/m amplitude) were tested in 10 immunodeficient mice bearing human adenocarcinomas (MX-1 cells). Histologic sections of heated tumor tissue were analyzed. RESULTS: SAR data of different magnetite particle types ranged from 3 to 211 W/g. Temperature elevation (DeltaT) as a function of the magnetite mass increased linearly up to 28 mg; at higher masses, a saturation of DeltaT was observed at nearly 88 degrees C. The dependence of DeltaT on magnetic field amplitude (H) revealed a third-order power law: DeltaT = 0.26 degrees C/(kA/m)(3). H(3), with r(2) = 0.95. A mean temperature of 71 degrees C +/- 8 was recorded in the tumor region at the end of magnetic field exposure of the mice. Typical macroscopic findings included tumor shrinkage after heating. Histologically nuclear degenerations were observed in heated malignant cells. CONCLUSION: Magnetic heating of breast tumors is a promising technique for future interventional radiologic treatments.

31P magnetic resonance spectroscopy in fibromyalgic muscle.

OBJECTIVE: To measure inorganic phosphate (Pi), phosphocreatine (PCr), ATP and phosphodiesters (PDE) in fibromyalgic muscle tissue by (31)P magnetic resonance spectroscopy. METHODS: A 1.5 Tesla scanner with a P 100 surface coil was used to examine 15 patients (mean age 49.9+/-14.3 yr) with fibromyalgia, according to the American College of Rheumatology criteria, and 17 healthy controls (mean age 30.2+/-5.8 yr). RESULTS: Compared with the controls, there were increases in the levels of PDE (+22%, P = 0.032) and Pi (+19%, P = 0.019) in the spectra of fibromyalgia patients, but there was no difference in pH. CONCLUSION: The metabolic differences we found may have been related to weakness and fatigue in the fibromyalgia patients, but they do not fully explain the fibromyalgia symptoms.

Discrepancy between nitrate reduction rates in intact leaves and nitrate reductase activity in leaf extracts: what limits nitrate reduction in situ?

Nitrate reductase (NR) activity in spinach leaf extracts prepared in the presence of a protein phosphatase inhibitor (50 microM cantharidine) was measured in the presence of Mg2+ (NRact) or EDTA (NRmax), under substrate saturation. These in-vitro activities were compared with nitrate reduction rates in leaves from nitrate-sufficient plants. Spinach leaves containing up to 60 micromol nitrate per g fresh weight were illuminated in air with their petiole in water. Their nitrate content decreased with time, permitting an estimation of nitrate reduction in situ. The initial rates (1-2 h) of nitrate consumption were usually lower than NRact, and with longer illumination time (4 h) the discrepancy grew even larger. When leaves were fed through their petiole with 30 mM nitrate, initial in-situ reduction rates calculated from nitrate uptake and consumption were still lower than NRact. However, nitrate feeding through the petiole maintained the in situ-nitrate reduction rate for a longer time. Initial rates of nitrate reduction in situ only matched NRact when leaves were illuminated in 5% CO2. In CO2-free air or in the dark, both NRact and in-situ nitrate reduction decreased, but NRact still exceeded in-situ reduction. More extremely, under anoxia or after feeding 5-amino-4-imidazole carboxyamide ribonucleoside in the dark, NR was activated to the high light level; yet in spite of that, nitrate reduction in the leaf remained very low. It was examined whether the standard assay for NRact would overestimate the in-situ rates due to a dissociation of the inactive phospho-NR-14-3-3 complex after extraction and dilution, but no evidence for that was found. In-situ NR obviously operates below substrate saturation, except in the light at high ambient CO2. It is suggested that in the short term (2 h), nitrate reduction in situ is mainly limited by cytosolic NADH, and cytosolic nitrate becomes limiting only after the vacuolar nitrate pool has been partially emptied.

Decreased frontal activation in schizophrenics during stimulation with the continuous performance test--a functional magnetic resonance imaging study.

The Continuous Performance Test (CPT) has become an essential constituent of the neuropsychological investigation of schizophrenia. Also, a vast number of brain imaging studies, mostly PET investigations, have employed the CPT as a cognitive challenge and established a relative hypofrontality in schizophrenics compared to controls. The aim of the present investigation was to clarify whether this predescribed hypofrontality could also be verified using functional magnetic resonance imaging (fMRI). 20 healthy volunteers and 14 schizophrenics on stable neuroleptic medication were included. Imaging was performed using the CPT-double-T-version and a clinical 1.5 T MRI-scanner with a single slice technique and a T(2)*-weighted gradient-echo-sequence. The schizophrenics exhibited a decreased activation in the right mesial prefrontal cortex, the right cingulate and the left thalamus compared to controls. These results obtained by fMRI are discussed in relation to published findings using PET.

[Intraoperative blood requirements and allogeneic blood transfusion in cardioanesthesia. Data analysis of 7729 patients in 12 cardiac surgical clinics]. / Intraoperativer Fremdblutverbrauch und Eigenbluttransfusion in der Kardioanästhesie. Datenanalyse von 7729 Patienten aus 12 herzchirurgischen Kliniken.

UNLABELLED: Allogeneic blood requirements in cardiac surgery shows a wide variation even for comparable procedures. The aim of the present study was to compare the intraoperative allogeneic blood requirement in defined cardiac operations among 12 cardiac centers in Germany. METHOD: A data set with 25 variables concerning the intraoperative course in adult cardiac patients with myocardial revascularization, valve replacement (aortic or/and mitral valve) or combined procedures was distributed to the participating centers. The data of all patients between January 1th 1998 and June 30th 1998 were included. Besides demographic data, the intraoperative transfusion of allogeneic and autologous blood, fresh frozen plasma and the concomitant hematocrit values were registered. Data were analyzed for all centers and separated for each center. RESULTS: The data of 7,729 patients were analyzed. The intraoperative allogeneic blood requirement was 0.6 +/- 1.3 units for all patients. It varied among the centers from 0.25 +/- 0.6 units to 0.97 +/- 1.6 units (P < 0.05). The percentage of patients receiving allogeneic blood was 27% and differed among the centers from 17% to 35%. Female patients were transfused in 53% (36-39%) compared to male patients with 16% (9-20%) (P < 0.05). The rate of autologous blood predonation varied from 0.5% to 23%. Patients without autologous predonation were transfused in 28% compared to 4% in patients with predonation (P < 0.05). In patients with autologous predonation the intraoperative transfusion of allogeneic blood was significantly reduced (0.1 +/- 0.39 vs 0.6 +/- 1.4 units, P < 0.05). However, some centers with a high percentage of autologous predonation also demonstrated a high rate of perioperative allogeneic transfusion. CONCLUSION: The incidence of allogeneic blood transfusion in cardiac surgery depends on the institution and not on the surgical procedure. A common threshold value of hemoglobin for the transfusion of blood trigger even for comparable procedures could not be detected among the centers. Especially in female patients, there was a wide variation in allogeneic blood transfusion. Autologous blood predonation reduces blood requirement significantly, however, it is practiced with variing intensity. The data set did not include information about transfusion regimen in the postoperative period, thus, these data do not allow to draw conclusions for the whole perioperative period.

31P-magnetic resonance spectroscopy (31P-MRS) of human allografts after renal transplantation.

BACKGROUND: 31P-Magnetic resonance spectroscopy (31P-MRS) can be used as a non-invasive tool for measuring the relative intracellular concentrations of several phosphorus metabolites in different organs. Various pathological conditions are characterized by different metabolic patterns. We studied the value of 31P-MRS after renal transplantation with both an uneventful and a clinically complicated course. METHODS: We determined the relative concentrations of phosphate-containing metabolites in renal allografts of humans with 31P-MRS (1.5 Tesla) in the first few weeks after transplantation; 18 patients with an uneventful clinical course and 10 patients who required dialysis after transplantation were examined. Six patients with a stable allograft function 2-3 months after transplantation served as controls. RESULTS: In patients with primary allograft function, we found a significant correlation between the phosphomonoester/phosphodiester-ratio (PME/PDE) (r = 0.66, r < 0.01) and the time after transplantation, but no correlation between the nucleoside triphosphate (beta-NTP)-concentration (r = -0.11) and the time course. In the patients with primary or early allograft dysfunction caused by histologically proven rejection (n=5), we found a low beta-NTP compared to patients with an uncomplicated clinical course (0.09+/-0.01 vs 0.15+/-0.03), but no differences in the PME/PDE ratio (0.73+/-0.21 vs 0.80+/-0.21). In contrast, the PME/PDE ratio was lowered in three patients with delayed graft function caused by acute tubular necrosis (0.45+/-0.07 vs 0.80+/-0.21), but the beta-NTP concentration was not reduced (0.15+/-0.003 vs 0.15+/-0.03). The 31P-MR spectrum of two patients with cyclosporin A damage was not altered compared to the controls. CONCLUSIONS: 31P-MRS can be used in patients in the early period after renal transplantation. A significant correlation between the PME/PDE ratio and the time course but no change in the beta-NTP concentration was found in patients with primary allograft function in the first 4 weeks after renal transplantation. Different patterns of 31P-MR spectra were observed depending on the different causes of primary and early transplant dysfunction.

High-energy phosphates in the frontal lobe correlate with Wisconsin Card Sort Test performance in controls, not in schizophrenics: a 31phosphorus magnetic resonance spectroscopic and neuropsychological investigation.

In recent years, a number of 31phosphorus magnetic resonance spectroscopy (P-MRS) studies on the frontal lobe of schizophrenics have been performed, reporting alterations of phospholipids and high-energy phosphates. Deicken et al. (1994b) recently found positive correlations between left frontal phosphomonoester% (PME%) levels and the performance of a specific frontal lobe task, the Wisconsin Card Sorting Test (WCST), in schizophrenics. In the present paper, the correlations between phospholipids and high-energy phosphates in the frontal lobe of 26 schizophrenics and 23 controls measured with a volume-selective P-MRS method were investigated. Overall, we could not find any correlations between WCST results and phospholipid levels, but in controls phosphocreatine% (PCr%) and PCr/adenenosine triphosphate (ATP) ratios were negatively correlated with test performance. Since PCr behaves as a buffer of ATP, in the sense that when ATP is consumed by neuronal activity PCr is catalysed rapidly to ATP, increased PCr% values and, moreover, increased PCr/ATP ratios point to a decreased ATP consumption. Thus, the correlations found between PCr% and PCr/ATP and test performance in controls point to an association between reduced performance in a specific frontal lobe task and decreased energy demanding processes at rest. This association was not found in schizophrenics, possibly due to the influence of neuroleptic medication or the disease process per se.

31P magnetic resonance spectroscopy in the frontal lobe of major depressed patients.

Most research with 31P-magnetic resonance spectroscopy (31P-MRS) in affective disorders has been done in the field of bipolar disturbances. Reduced frontal and temporal lobe phosphomonoester (PME) concentrations were measured in the euthymic state, whereas increased values were found in the depressed state. In bipolar-II patients reduced phosphocreatine (PCr) concentrations were reported in the euthymic, depressed, and manic state. The aim of the present study was to explore whether PME and PCr were also altered in the frontal lobe of major depressed, unipolar patients. Therefore, we used 31P-MRS to investigate the relative phospholipid and high-energy phosphate concentrations in the frontal lobe of 14 unipolar patients, mostly medicated, and 8 age-matched controls. We found increased PME and decreased ATP values. Other 31P-MRS parameters were not different in both groups. Phosphomonoester percentages correlated negatively with the degree of depression. Thus, the main alterations found in bipolar depressed patients could also be demonstrated in unipolar depressed patients. The results are discussed with regard to disturbed phospholipid and intracellular high-energy phosphate metabolism in depressed patients.

Evaluation of temperature increase with different amounts of magnetite in liver tissue samples.

RATIONALE AND OBJECTIVES: The biologic effects of magnetically induced heating effects using iron oxide, magnetite, were examined in vitro in liver tissue samples as a first step toward potential applications in cancer therapy. METHODS: For the determination of the temperature profile around an iron oxide sample, a cylinder containing 170 mg of magnetite was constructed and placed into pureed liver tissue from pig, together with thermocouples of copper and constantan wires positioned at defined distances from it. Temperature measurements were performed during the exposure to an alternating magnetic field (frequency: 400 kHz; amplitude: approximately 6.5 kA/m) generated by a circular coil (90 mm of diameter). Moreover, variable amounts of magnetite (dissolved in approximately 0.2 mL physiologic saline) were injected directly into carrageenan gels. During the exposure to a magnetic field for 4 minutes the temperature increase was determined in the area of iron oxide deposition using a thermocouple. Additionally, variable amounts of magnetite were injected directly into isolated liver tissue samples (diameter: 20 mm; height: 30 mm) and exposed to a magnetic field for 2 minutes. The extent of the induced macroscopically visible tissue alterations (light brown colorations caused by heating) was examined by means of volume estimations. The degrees of cellular necrosis were investigated by histopathologic studies. RESULTS: The temperature profile around a magnetite cylinder revealed a significant decrease of temperature difference between the beginning and the end of heating, depending on increasing distance from the sample center. The extent of the temperature difference correlated with increasing heating time. No significant variations of temperature were observed at a distance of approximately 12 mm from the sample center. A good correlation (r = 0.98) between the injected amounts (31 to 200 mg) and the temperature increase since the start of heating (6.8-33.7 degrees C) in the area of iron oxide deposits was detected. The volume of damaged liver tissue was approximately seven times higher than the injected volume of iron oxide dispersion. Histologically different degrees of cellular necrosis were observed. CONCLUSIONS: The parameters determined in this article show that iron oxides are able to induce considerable heating effects in the surroundings. After an adequate optimization of the technical procedure, it is conceivable that heating properties of magnetites can be used in future cancer treatments.