Creatine deficiency in the brain: a new, treatable inborn error of metabolism

In a patient with extrapyramidal movement disorder and extremely low creatinine concentrations in serum and urine, in vivo proton magnetic resonance spectroscopy disclosed a generalized depletion of creatinine in the brain. Oral substitution of arginine, a substrate for creatine synthesis, resulted in an increase of brain guanidinoacetate as the immediate precursor of creatine but did not elevate cerebral creatine levels. In contrast, oral substitution of creatine-monohydrate led to a significant increase of brain creatine, a decrease of brain guanidinoacetate, and a normalization of creatinine in serum and urine. Phosphorus magnetic resonance spectroscopy of the brain revealed no detectable creatine-phosphate before oral substitution of creatine and a significant increase afterward. Partial restoration of cerebral creatine concentrations was accompanied by improvement of the patient's neurologic symptoms. This is the first report of a patient with complete creatine deficiency in the brain. Magnetic resonance spectroscopy during arginine and creatine treatment point to an inborn error of creatine biosynthesis at the level of guanidinoacetete-methyltransferase.

MR spectroscopy shows reduced frontal lobe concentrations of N-acetyl aspartate in patients with juvenile myoclonic epilepsy

PURPOSE

Neuropsychological studies suggest frontal lobe dysfunctions in patients with juvenile myoclonic epilepsy (JME). In this study we investigated whether an underlying mechanism could be a regional neuronal damage not visible with structural magnetic resonance (MR), but detectable with magnetic resonance spectroscopy (MRS).

METHODS

The study included 15 patients with JME and 10 matched healthy controls. Quantitative single voxel MRS was conducted at 1.5 Tesla by using a STEAM sequence (TR/TE/TM = 6,000/30/13.7 ms). The voxels were placed over the right cerebellum, right thalamus, and the prefrontal and occipital cortex. The quantitation included fitting of transmitter gain, and correction for partial volume of cerebrovascular fluid. LC-Model was used for estimation of the absolute concentrations of total N-acetyl aspartate (NAA), cholines, total creatine, and myoinositol.

RESULTS

Patients with JME had significantly reduced prefrontal concentrations of NAA in relation to controls (9.1 +/- 1.0 vs. 10.2 +/- 0.8 mM; p = 0.031 after Bonferroni correction). The other regions showed normal NAA values, as did the other metabolites.

CONCLUSIONS

The observed reduction in NAA levels suggests a prefrontal neuronal lesion in patients with JME.

MRS shows syndrome differentiated metabolite changes in human-generalized epilepsies

OBJECTIVE

While it is generally accepted that the thalamo-cortical loop is abnormal in idiopathic generalized epilepsy (IGE), it is uncertain whether this loop is similarly affected among different IGE syndromes. We recently demonstrated reduced frontal lobe levels of N-acetyl aspartate (NAA) in patients with juvenile myoclonic epilepsy (JME). The present follow-up study investigates if similar or other types of changes exist in subjects with pure primarily generalized tonic clonic epilepsy (GTCS).

METHOD

Twenty patients with GTCS, 26 patients with JME, and 10 matched healthy controls were investigated with quantitative single voxel MR spectroscopy (MRS) measurements of NAA, choline (Cho), creatine (Cr), and myo-inositol (mI) at 1.5 T scanner. The voxels were placed over the right cerebellum, right thalamus, prefrontal, occipital cortex, and over a spherical phantom above the subject's head.

RESULTS

Patients with JME had reduced frontal lobe NAA (mmol/l) in relation to controls (9.8 +/- 1.1 vs. 10.8 +/- 0.7, P = 0.01), as well as GTCS patients (9.8 +/- 1.1 vs. 10.6 +/- 0.7, P = 0.007), whose values were normal. Patients with GTCS, on the other hand, showed significantly lower thalamic NAA than controls (9.7 +/- 1.0 vs. 10.8 +/- 0.9, P = 0.002), and both groups of patients had reduced thalamic Cho, and mI; [CHO: 2.0 +/- 0.4 (control) vs. 1.61 +/- 0.3 (JME) P = 0.001, and vs. 1.57 +/- 0.3 (GTCS) P = 0.0005; MI: 4.8 +/- 1.5 (control) vs. 3.3 +/- 1.4 (JME) P = 0.003, and vs. 3.2 +/- 1.5 (GTCS), P = 0.002]. No other regional changes were observed.

CONCLUSION

The present MRS data emphasize the involvement of thalamus in IGE. They also show partly differentiated alterations within the thalamo-cortical loop in JME vs. GTCS. The various clinical expressions of IGE may, thus, be associated with more localized neuroanatomical substrates than generally believed.

Genetic diversity of algal and fungal partners in four species of Umbilicaria (Lichenized Ascomycetes) along a transect of the Antarctic peninsula

Lichens from the genus Umbilicaria were collected across a 5,000-km transect through Antarctica and investigated for DNA sequence polymorphism in a region of 480-660 bp of the nuclear internal transcribed spacer region of ribosomal DNA. Sequences from both fungal (16 ascomycetes) and photosynthetic partners (22 chlorophytes from the genus Trebouxia) were determined and compared with homologs from lichens inhabiting more temperate, continental climates. The phylogenetic analyses reveal that Antarctic lichens have colonized their current habitats both through multiple independent colonization events from temperate embarkation zones and through recent long-range dispersal in the Antarctic of successful preexisting colonizers. Furthermore, the results suggest that relichenization-de novo establishment of the fungus-photosynthesizer symbiosis from nonlichenized algal and fungal cells-has occurred during the process of Antarctic lichen dispersal. Independent dispersal of algal and fungal cultures therefore can lead to a successful establishment of the lichen symbiosis even under harsh Antarctic conditions.

Increased thalamus levels of glutamate and glutamine (Glx) in patients with idiopathic generalised epilepsy

OBJECTIVE

Abnormal thalamo-cortical oscillations underlie idiopathic generalised epilepsy (IGE). Although thalamic involvement has long been indicated by electrophysiological data, it has only recently become feasible to test this with independent methods. In this magnetic resonance (MR) study, we investigated the metabolic and structural integrity of the thalamus. Possible changes in glutamine and glutamate concentrations and signs of neuronal damage were of particular interest.

METHOD

Forty three IGE patients and 38 age and sex matched healthy controls were investigated. Quantitative single volume MR spectroscopy (MRS, 1.5 T) was used to measure concentrations of glutamate and glutamine (Glx) and N-acetyl aspartate (NAA) in thalamus and occipital cortex. We also measured thalamic volumes on high resolution gradient-echo images and estimated fractions of thalamic grey and white matter with voxel based morphometry (VBM).

RESULTS

IGE patients showed elevated Glx and reduced NAA concentrations in the thalamus compared to controls (12.2+/-2.6 v 8.9+/-4.1 mM, p = 0.0022 for Glx, and 9.9+/-1.0 v 10.7+/-0.9 mM, p = 0.017 for NAA). Thalamic grey matter fraction was reduced in IGE patients, and white matter fraction was increased with the greatest increase in the dorso-medial thalamus. Mean thalamic volume was reduced in patients (6.7+/-0.7 v 7.2+/-0.6 ml in controls, p = 0.0001), as was mean cerebral volume (1163+/-128 v 1250+/-102 ml, p = 0.0003). Patients' thalamus/whole brain ratios were normal.

CONCLUSION

Quantitative MRS and VBM provide further evidence for involvement of the thalamus in IGE. The observed elevation of Glx levels together with reductions in NAA levels and grey matter fractions are consistent with epilepsy related excitoxicity as a possible underlying mechanism.

Differentiation of typical and atypical Parkinson syndromes by quantitative MR imaging

BACKGROUND AND PURPOSE

The differential diagnosis of Parkinson syndromes remains a major challenge. Quantitative MR imaging can aid in this classification, but it is unclear which of the proposed techniques is best suited for this task. We, therefore, conducted a head-to-head study with different quantitative MR imaging measurements in patients with IPS, MSA-type Parkinson, PSP, and healthy elderly controls.

MATERIALS AND METHODS

Thirty-one patients and 13 controls underwent a comprehensive quantitative MR imaging protocol including R2*-, R2- and R1-mapping, magnetization transfer, and DTI with manual region-of-interest measurements in basal ganglia regions. Group differences were assessed with a post hoc ANOVA with a Bonferroni error correction and an ROC.

RESULTS

The best separation of MSA from IPS in patients and controls could be achieved with R2*-mapping in the PU, with an ROC AUC of ≤0.96, resulting in a sensitivity of 77.8% (with a specificity 100%). MD was increased in patients with PSP compared with controls and to a lesser extent compared with those with IPS and MSA in the SN.

CONCLUSIONS

Among the applied quantitative MR imaging methods, R2*-mapping seems to have the best predictive power to separate patients with MSA from those with IPS, and DTI for identifying PSP.

ICG Fluorescence Technique for the Detection of Sentinel Lymph Nodes in Breast Cancer: Results of a Prospective Open-label Clinical Trial

Introduction: Detection of sentinel lymph nodes (SLN) is the standard procedure to evaluate axillary lymph node status in breast cancer. In addition to known and established procedures such as the blue dye method and scintigraphy, this study investigated the efficacy of a method based on use of the fluorescent dye indocyanine green (ICG). Patients and Method: A total of 126 women with breast cancer histologically verified by punch biopsy were studied during surgical removal of SLN. In addition to SLN marking with technetium and scintigraphy, intra-individual comparison was done using indocyanine green (ICG) for marking instead of the standard blue dye. Results: Scintigraphy had a detection rate of 96 %; the detection rate with ICG was just under 89 %. A body mass index (BMI) > 40 was found to be a limiting factor for the fluorescent method. Investigation into potential toxicities associated with the use of the fluorescent dye ICG revealed no systemic or even local side effects. The fluorescent method was found to be significantly less expensive than the scintigraphy method. Conclusion: The ICG fluorescence technique for the detection of SLN was found to be a valid and feasible method in clinical practice when compared directly with the blue dye method and scintigraphy.

Identification of Scyllo-inositol in proton NMR spectra of human brain in vivo

Scyllo-inositol has been identified in proton NMR spectra of mammalian brain in vitro and in vivo. In contrast to myo-inositol this isomer comprises six equivalent CH protons that yield a singlet resonance at a chemical shift of 3.35 ppm. 1-D and 2-D J-resolved proton NMR studies (7.0 T) of perchloric acid extracts of brain tissues revealed different amounts of scyllo-inositol in man, sheep, cow and rat. Absolute quantification of localized short-echo time proton NMR spectra (2.0 T) of human brain in vivo resulted in scyllo-inositol concentrations of 0.35 +/- 0.06 mM for white matter (n = 25), 0.43 +/- 0.11 mM for grey matter (n = 23) and 0.57 +/- 0.14 mM for cerebellum (n = 10). Evidence for a tight metabolic link to myo-inositol was supported by a simultaneous variation of myo- and scyllo-inositol in patients with various brain diseases.

Restoration of motion-related signal loss and line-shape deterioration of proton MR spectra using the residual water as intrinsic reference

A postprocessing method to restore motion-related signal loss and line-shape deterioration in single-volume proton MR spectroscopy (MRS) is presented. Each acquisition is corrected by its phase offset and frequency shift, extracted from the residual water signal prior to averaging. Requirements are good gradient selection and selective suppression of CSF in residual water. Stimulated echo acquisition mode (STEAM) spectra (TE = 30 ms) were analyzed using the LCModel program to study gains in metabolite signal and spectral quality in five brain regions. Increases of total N-acetyl-aspartate concentrations of up to 5% were observed. The method may be beneficial for clinical examinations of less compliant subjects and for dynamic spectroscopy.

Sentinel-node biopsy for axillary staging in breast cancer: results from a large prospective German multi-institutional trial

PURPOSE

To analyse the reliability of sentinel-node biopsy (SNB) in a multicentre setting and define conditions for the routine use of the procedure.

MATERIAL AND METHODS

SNB with consecutive axillary clearing was performed in 1124 breast cancer patients. The detection rate of a sentinel lymph node and its dependence on the choice of lymphography technique, patient selection, and technical procedure were analysed. The diagnostic performance of the sentinel-node method was compared to clinical, ultrasound-guided and histological staging. In order to study training effects all learning periods were included.

RESULTS

Twenty-two institutions with a total of 89 surgeons participated in the trial. The detection rate (overall: 85.2%) was found to be related to the applied lymphography technique, the experience of the institution and various technical factors of the procedure itself. The false-negative rate (FNR, overall: 8.2%) was independent of patient selection and technical features. The FNR did not depend on experience in the application of the method, but seemed related to surgical accuracy to detect sentinel nodes. Compared to conventional staging procedures (palpation, ultrasound) SNB yielded highly reproducible results for the prediction of the axillary status even in a multicentre setting involving surgeons with different training status.

CONCLUSION

SNB is suited as standard of care procedure. Measures of quality control appear more important than learning periods to minimize the FNR.

Disentangling in vivo the effects of iron content and atrophy on the ageing human brain

Evidence from magnetic resonance imaging (MRI) studies shows that healthy aging is associated with profound changes in cortical and subcortical brain structures. The reliable delineation of cortex and basal ganglia using automated computational anatomy methods based on T1-weighted images remains challenging, which results in controversies in the literature. In this study we use quantitative MRI (qMRI) to gain an insight into the microstructural mechanisms underlying tissue ageing and look for potential interactions between ageing and brain tissue properties to assess their impact on automated tissue classification. To this end we acquired maps of longitudinal relaxation rate R1, effective transverse relaxation rate R2* and magnetization transfer - MT, from healthy subjects (n=96, aged 21-88 years) using a well-established multi-parameter mapping qMRI protocol. Within the framework of voxel-based quantification we find higher grey matter volume in basal ganglia, cerebellar dentate and prefrontal cortex when tissue classification is based on MT maps compared with T1 maps. These discrepancies between grey matter volume estimates can be attributed to R2* - a surrogate marker of iron concentration, and further modulation by an interaction between R2* and age, both in cortical and subcortical areas. We interpret our findings as direct evidence for the impact of ageing-related brain tissue property changes on automated tissue classification of brain structures using SPM12. Computational anatomy studies of ageing and neurodegeneration should acknowledge these effects, particularly when inferring about underlying pathophysiology from regional cortex and basal ganglia volume changes.

Ultrasound-guided large-core needle biopsies of breast lesions: analysis of 962 cases to determine the number of samples for reliable tumour classification

The objective of this one-institutional study was to determine the number of large-core needle biopsies (LCNB), under three-dimensional ultrasound (3D-US) validation, that are sufficient to obtain a reliable histological diagnosis of a sonographically detectable breast lesion. Over an 28-month period, 962 sonographically guided LCNB were performed under 3D-US validation to assess 962 breast lesions. All biopsies were carried out with an automated core biopsy device fitted with 14-gauge (22 mm excursion) needles. Data of 962 biopsied breast lesions were gathered. Surgical follow-up was available for 659 lesions. Breast malignancies were diagnosed by ultrasound-guided LCNB with a sensitivity of 98.2% by performing three cores per lesion. In few cases, the open surgical specimen revealed the presence of invasive carcinomas in contrast to initial LNCB-based classification as ductal carcinomas in situ (DCIS, 11 lesions), lobular carcinoma in situ (one lesion), and atypical ductal hyperpasia (one lesion). Owing to disagreement between classification based on breast-imaging and histological findings, eight of these tumours were subsequently excised. Of the lesions that were removed at the patients’ requests despite benign LCNB diagnosis, two were infiltrating carcinoma and one a DCIS. We demonstrate that three 3D-US-guided percutaneous core specimens are sufficient to achieve tissue for a reliable histological assessment of sonographically detectable breast lesions and allow the detection of malignancies with high sensitivity and low rate of false-negative diagnoses.

Volume correction for edema in single-volume proton MR spectroscopy of contrast-enhancing multiple sclerosis lesions

The effect of edema on metabolic changes in contrast-enhancing multiple sclerosis lesions was studied by combining quantification of proton MR spectra with segmentation of the volume-of-interest, which was based on biexponential T(2) relaxation. All lesions showed a second component (s(long)) with a longer T(2) (185-450 ms), which was increased compared to healthy controls. Regression analysis indicated that s(long) replaces the short-T(2) component and total creatine. Since the water content was close to 100%, s(long) was used to correct for an increase in extracellular space. This compensated for the apparent loss of creatine and rendered cholines markedly increased, as observed in animals with experimental allergic encephalomyelitis. Total N-acetyl aspartate (NAA) concentration was inversely correlated with s(long) and between 34-70% of its average reduction was assigned to edema. Thus, NAA loss exceeded cellular loss. Assessment of varying degrees of edema may be especially beneficial for quantitative longitudinal studies.

A precise and user-independent quantification technique for regional comparison of single volume proton MR spectroscopy of the human brain

The aim of this work was to study and correct the influence of varying coil load and local B(1) field in single volume MR spectroscopy. A simple, precise, and user-independent way to adjust the transmitter gain has been developed and validated. It is based on a fit of the localized signal to flip angle variation around 90 degrees. This method proved to be robust against B(1) gradients and suitable for in vivo applications. Local B(1) correction was combined with an external reference and decomposition of the volume into CSF and tissue to obtain a comprehensive absolute quantification of tissue water content and metabolite concentrations in human brain. STEAM localized spectra of parietal and insular gray matter and subparietal white matter (n = 11, TE = 30 ms) were analyzed using a linear combination of model spectra (LCModel). Coefficients of variation (CV) between 1.5% and 4% were obtained for the tissue water content (1-2% in a single subject). The CVs of major metabolite concentrations (4-21%) were dominated by the errors of the spectral analysis. The largest B(1) variation in the in vivo experiments (range 30%) was due to changes in coil load. Differences in regional sensitivity due to B(1) inhomogeneity (parietal: 8% and 9%; insular: 16%) were found to be the second largest source of variation. Correction for local B(1) improved standard deviations and intra-subject reproducibility. On average, sensitivity was 9% less in insular than in parietal gray matter. If ignored, significant differences were introduced for water and N-acetyl-aspartate or were obscured for creatine and cholines. Hence, local sensitivity correction proved to be necessary for regional comparison of absolute metabolite concentrations.

Improved visibility of the subthalamic nucleus on high-resolution stereotactic MR imaging by added susceptibility (T2*) contrast using multiple gradient echoes

Reliable identification of the subthalamic nucleus (STN) is a critical step in deep brain stimulation for Parkinson disease but difficult on T1-weighted stereotactic MR imaging. By simultaneous imaging of multiple gradient echoes, susceptibility contrast is added to conventional T1-weighted high-resolution MR image. Thus, the visibility of the STN is enhanced on a second co-localized dataset by exploiting the sensitivity of the T2*-relaxation to local iron deposits. The feasibility is underpinned by quantitative measurements on healthy adults.

Diffusion characteristics of large molecules assessed by proton MRS on a whole-body MR system

Methods for examinations of diffusion of large molecules of the size of fatty acids or triglycerides were developed for whole body MR units. Samples of aliphatic molecules were examined to study the influence of chain length. Feasibility under in vivo conditions was tested on lard samples at 37 degrees C and on human subjects Three stimulated echo sequences with maximum b-values of 2000 s/mm(2), 20000 s/mm(2), and 80000 s/mm(2) were used to assess a wide range of mobility. Sequence timing was optimized to minimize relaxation losses of fatty tissue. Apparent diffusion coefficients (ADC) were determined from five spectra with different diffusion weighting. In-vitro experiments were performed on butanol, decanol, and oleic acid to study the influence of chain length. In vivo conditions were mimicked using lard at 37 degrees C representing a composition of substances of various chain lengths. Subcutaneous fat and tibial bone marrow were studied in three healthy volunteers. ADC of muscular lipids of the lower leg was determined in two subjects. ADC values of pure aliphatic substances were in the range between 3.2 x 10(-5) mm(2)/s for oleic acid and 37.8 x 10(-5) mm(2)/s for butanol. In vivo investigations revealed ADC values of 1.11-1.24 x 10(-5) mm(2)/s for tibial bone marrow and 1.21-2.05 x 10(-5) mm(2)/s for subcutaneous fat. Diffusion coefficients of extra- and intramyocellular lipids were 1.83-3.65 x 10(-5) mm(2)/s and 2.22-3.60 x 10(-5) mm(2)/s, respectively. The proposed technique enables determination of ADC values of relatively large molecules and of lipid tissue compartments under in vivo conditions. Diffusion properties in several human lipid compartments are reported for the first time. Incoherent voxel motion influences the in vivo results to an unknown degree because of high motion sensitivity. In vitro experiments revealed ADC values depending on the chain length of the substances, indicating a residual dependence of measured ADC's on sequence timing.

Regression analysis of metabolite concentrations estimated from localized proton MR spectra of active and chronic multiple sclerosis lesions

Localized short echo time magnetic resonance (MR) spectra were obtained from patients with multiple sclerosis of relapsing-remitting or secondary chronic-progressive course and from healthy controls. Automated analysis using model spectra, sensitivity correction, and subtraction of partial ventricular volume yielded tissue concentrations of metabolites that were in line with findings of previous studies. Additional findings were increased creatine in chronic lesions and increased myo-inositol in normal-appearing white matter. Regression analysis was performed to reveal concomitant changes of metabolite concentrations. Differences in the correlations between cholines and myo-inositol suggest increased expression of myo-inositol in chronic lesions or of cholines in active, contrast-enhanced lesions. A correlation between N-acetyl-aspartate and creatine, which is probably due to extracellular edema, was observed in active but not in chronic lesions. Creatine and cholines correlated in chronic lesions, which may be the result of gliosis. The consequences of these findings for the interpretation of absolute concentrations and creatine ratios are discussed.

Analysis of 1.5 Tesla proton MR spectra of human brain using LCModel and an imported basis set

Automated analysis of 1.5 Tesla proton mass MR spectra using the LCModel program with basis sets obtained at other sites is expected to become more widespread, as such basis sets are now generally available. A calibration procedure to estimate absolute concentrations with such imported basis sets is suggested and the implications for differential T2 attenuation are discussed. Based on STEAM localized spectra from parietal gray (n = 51) and white matter (n = 43), of which 28 (18 rsp) were quantified, the evaluation of 30 ms echo time (TE) spectra was validated against published results that were obtained at 2 Tesla and 20 ms TE. Good agreement for both absolute concentrations and metabolite ratios confirmed the usefulness of LCModel analysis with an imported basis set. However, in white matter, glutamine tended to be overestimated, and was assigned either to signal-to-noise depending baseline effects or the use of choline. Mutual interdependence of metabolites inherent to LCModel analysis is discussed in detail.

Metabolic alterations in brain autopsies: proton NMR identification of free glycerol

Metabolic alterations in bovine brain homogenate were examined as a function of post mortem interval (PMI) using high-resolution proton NMR spectroscopy. In particular, while lactate, glutamate, glutamine, creatine and inositols as well as the total concentration of trimethyl-ammonium compounds remained constant, prominent changes due to the hydrolysis of N-acetylaspartate to acetate and aspartate as well as the decomposition of glycerophosphocholine into free choline and glycerol correlated linearly with the duration of PMI (3-195 h). The spectroscopic identification of the latter process was confirmed by proton NMR studies of model solutions as well as of extracts of mammalian brain showing high levels of free glycerol. Since the methylene resonances of glycerol overlap with the proton resonances of myo-inositol, care should be taken in the interpretation of both in vitro and in vivo brain spectra.

Noninvasive estimation of tumour viability in a xenograft model of human neuroblastoma with proton magnetic resonance spectroscopy (1H MRS)

The aim of the study was to evaluate proton magnetic resonance spectroscopy ((1)H MRS) for noninvasive biological characterisation of neuroblastoma xenografts in vivo. For designing the experiments, human neuroblastoma xenografts growing subcutaneously in nude rats were analysed in vivo with (1)H MRS and magnetic resonance imaging at 4.7 T. The effects of spontaneous tumour growth and antiangiogenesis treatment, respectively, on spectral characteristics were evaluated. The spectroscopic findings were compared to tumour morphology, proliferation and viable tumour tissue fraction. The results showed that signals from choline (Cho)-containing compounds and mobile lipids (MLs) dominated the spectra. The individual ML/Cho ratios for both treated and untreated tumours were positively correlated with tumour volume (P<0.05). There was an inverse correlation between the ML/Cho ratio and the viable tumour fraction (r=-0.86, P<0.001). Higher ML/Cho ratios concomitant with pronounced histological changes were seen in spectra from tumours treated with the antiangiogenic drug TNP-470, compared to untreated control tumours (P<0.05). In conclusion, the ML/Cho ratio obtained in vivo by (1)H MRS enabled accurate assessment of the viable tumour fraction in a human neuroblastoma xenograft model. (1)H MRS also revealed early metabolic effects of antiangiogenesis treatment. (1)H MRS could prove useful as a tool to monitor experimental therapy in preclinical models of neuroblastoma, and possibly also in children.

Increased growth of colorectal liver metastasis following partial hepatectomy

Nearly 50 % of colorectal cancer (CRC) patients develop liver metastases with liver resection being the only option to cure patients. Residual micrometastases or circulating tumor cells are considered a cause of tumor relapse. This work investigates the influence of partial hepatectomy (PH) on the growth and molecular composition of CRC liver metastasis in a syngeneic rat model. One million CC531 colorectal tumor cells were implanted via the portal vein in WAG/Rij rats followed by a 30 % PH a day later. Control groups either received tumor cells followed by a sham-operation or were injected with a buffer solution followed by PH. Animals were examined with magnetic resonance imaging (MRI) and liver tissues were processed for immunolabeling and PCR analysis. One-third PH was associated with an almost threefold increase in relative tumor mass (MRI volumetry: 2.8-fold and transcript levels of CD44: 2.3-fold). Expression of molecular markers for invasiveness and aggressiveness (CD49f, CXCR4, Axin2 and c-met) was increased following PH, however with no significant differences when referring to the relative expression levels (relating to tumor mass). Liver metastases demonstrated a significantly higher proliferation rate (Ki67) 2 weeks following PH and cell divisions also increased in the surrounding liver tissue. Following PH, the stimulated growth of metastases clearly exceeded the compensation in liver volume with long-lasting proliferative effects. However, the distinct tumor composition was not influenced by liver regeneration. Future investigations should focus on the inhibition of cell cycle (i.e. systemic therapy strategies, irradiation) to hinder liver regeneration and therefore restrain tumor growth.

Localized proton magnetic resonance spectroscopy of cerebral abnormalities in children with carbohydrate-deficient glycoprotein syndrome

Morphologic and metabolic abnormalities in six children aged 2-9 years with carbohydrate-deficient glycoprotein (CDG) syndrome were assessed by magnetic resonance imaging (MRI) and localized proton magnetic resonance spectroscopy (MRS). In all patients, MRI revealed pronounced cerebellar atrophy. Follow-up examinations in two patients suggested early onset and rapid progression in the first years of life. Further pathologies comprised Dandy-Walker malformation, atrophy of the pons, brain stem and olives, supratentorial frontotemporal cortical atrophy, slightly dilated ventricles and a small corpus callosum. Two patients presented with small cysts in the white matter. The prominent metabolic abnormality detected by proton MRS in five patients was a reduction in N-acetylaspartate in white matter by more than 20%, indicating loss of vital neuroaxonal tissue. Further findings in white matter were glutamine and gamma-aminobutyrate increases by a factor of 2. One patient with type III CDG syndrome showed the most severe alterations of metabolite concentrations.

Magnetization transfer attenuation of creatine resonances in localized proton MRS of human brain in vivo

To assess putative magnetization transfer effects on the proton resonances of cerebral metabolites in human brain, we performed quantitative proton magnetic resonance spectroscopy (2.0 T, STEAM, TR/TE/TM = 6000/40/10 ms, LCModel data evaluation) of white matter (7.68 mL, 10 healthy young subjects) in the absence and presence of fast repetitive off-resonance irradiation (2.1 kHz from the water resonance) using a train of 100 Gaussian-shaped RF pulses (12.8 ms duration, 120 Hz nominal bandwidth, 40 ms repetition period, 1080 degrees nominal flip angle). A comparison of pertinent metabolite concentrations revealed a magnetization transfer attenuation factor of the methyl and methylene resonances of creatine and phosphocreatine of 0.87 +/- 0.05 (p < 0.01). No attenuation was observed for the resonances of N-acetylaspartate and N-acetylaspartylglutamate, glutamate and glutamine, choline-containing compounds, and myo-inositol. The finding for total creatine is in excellent agreement with data reported for rat brain. The results are consistent with the hypothesis of a chemical exchange of mobile creatine or phosphocreatine molecules with a small immobilized or 'bound' pool.