Evaluation of two-dimensional L-COSY and JPRESS using a 3 T MRI scanner: from phantoms to human brain in vivo

Localized versions of two-dimensional (2D) magnetic resonance spectroscopic (MRS) sequences, namely JPRESS and L-COSY, have been implemented on a whole-body 3T MRI/MRS scanner. Volume selection was achieved using three slice-selective radio-frequency (RF) pulses: 90 degrees-180 degrees-180 degrees in JPRESS and 90 degrees-180 degrees-90 degrees in L-COSY with a CHESS sequence prior to voxel localization for global water suppression. The last 180 degrees RF pulse was used for resolving the J-coupled cross peaks in JPRESS, whereas the last 90 degrees RF pulse was used for coherence transfer between J-coupled metabolites in L-COSY. A head MRI coil for 'transmission' and a 4 inch receive surface coil for 'reception' or a head coil transmit/receive were used. A total of 16 healthy volunteers were investigated using these 2D MRS sequences. Voxel sizes of 18 and 27 ml were localized in the occipito-parietal gray and white matter regions and the total duration for each 2D signal acquisition was typically 35 min. Compared with 2D L-COSY, reduced spectral width along the second spectral dimension and shorter 2D spectral acquisition were the major advantages of 2D JPRESS. In contrast, increased spectral width along the new spectral dimension in L-COSY resulted in an improved spectral dispersion enabling the detection of several brain metabolites at low concentrations that have not been resolved using the conventional one-dimensional (1D) MRS techniques. Due to increased sampling rate, severe loss of metabolite signals due to T2 during t1 was a major drawback of 2D JPRESS in vivo.     

A semi‐LASER,single‐voxel spectroscopic sequence with a minimal echo time of 20.1 ms in the human brain at 3 T

An optimized semi‐LASER sequence that is capable of acquiring artefact‐free data with an echo time (TE) of 20.1 ms on a standard clinical 3 T MR system was developed. Simulations were performed to determine the optimal TEs that minimize the expected Cramér‐Rao lower bound (CRLB) as proxy for quantification accuracy of metabolites. Optimized RF pulses, crusher gradients and phase cycling were used to achieve the shortest TE in a semi‐LASER sequence to date on a clinical system. Synthetic spectra were simulated using the density matrix formalism for TEs spanning from 20.1 to 220.1 ms. These simulations were used to calculate the expected CRLB for each of the 18 metabolites typically considered in ¹H MRS. High quality spectra were obtained in six healthy volunteers in the prefrontal cortex, which is known for spurious echoes due to its proximity to the paranasal sinuses, and in the parietal‐occipital cortex. Spectral transients were sufficient in quality to enable phase and frequency alignment prior to summation over all repetitions. Automated high‐quality water suppression was obtained for all voxels without manual adjustment. The shortest TE minimized the CRLB for all brain metabolites except glycine due to its overlap with myo‐inositol at this TE. It is also demonstrated that the CRLBs increase rapidly with TE for certain coupled metabolites.     

High frequency and strong prognostic relevance of O6-methylguanine DNA methyltransferase silencing in diffuse large B-cell lymphomas from the Middle East

Several clinically relevant molecular classifiers of diffuse large B-cell lymphoma (DLBCL) have recently been demonstrated in Western populations. However, substantial molecular differences have recently been shown between tumors derived from different ethnic groups. To investigate prevalence and interrelationship of recently suggested molecular prognostic markers in Middle East DLBCL, we analyzed coexpression of CD10/Bcl6 (by immunohistochemistry), t(14;18) translocations (by fluorescence in situ hybridization), and methylation of the gene encoding the DNA repair enzyme O(6)-methylguanine DNA methyltransferase (MGMT) in a series of 190 DLBCL patients from Saudi Arabia with clinical follow-up data. Coexpression of CD10/Bcl6 (germinal center-like immunophenotype) was found in 13%, t(14;18) translocations in 17.9%, and MGMT methylation in 75.9% of cases. There was a trend toward better prognosis (although statistically insignificant) in tumors with coexpression of CD10/Bcl6. MGMT methylation were significantly related to good prognosis. The combined analysis of both parameters revealed that MGMT methylation was independent of immunophenotype and remained a significant predictor of prognosis in nongerminal center-like DLBCL subgroup. t(14;18) was significantly associated with CD10/Bcl6 coexpression (46.7%) but infrequent in CD10-/Bcl6-negative lymphomas (9.4%; P = .0073). However, t(14;18) was unrelated to clinical outcome. In summary, our data suggest a strong prognostic importance of MGMT methylation independent of DLBCL immunophenotype. Based on previous data from Western patients, the rate of MGMT hypermethylation was higher, and the portion of germinal center-like DLBCL was lower than expected. These results provide evidence for molecular differences between Saudi Arabian and Western DLBCL.     

An experimental method of identifying and quantifying the active transfer electrogenic component from the diffusive component during sugar absorption measured in vivo.

1. The kinetics of absorption of glucose, galactose and alpha-methyl glucoside have been measured in rat jejunum in vivo using a chemical method and a new electrical technique. 2. Sugar absorption estimated by chemical methods exhibited two components. One component was phlorrhizin-sensitive, saturable and generated electrical potential differences (electrogenic active component) while the other was phlorrhizin-insensitive, non-saturable and did not generate electrical potentials (diffusive component). 3. The diffusive component of the actively transported sugars was indentical to the absorption behaviour of sorbose, a hexose that is not actively transferred. 4. A method for correcting the data obtained from chemical absorption studies for the diffusive component was developed. The corrected, operational kinetic constants for 'apparent Km' obtained by this method were not significantly different to values obtained electrically. The identity between the values obtained by both methods supports the concept that they represent a measure of the same rate-limiting step in the absorption process. 5. The application and significance of the techniques is discussed in relation to the clinical assessment of intestinal sugar absorption.     

Signal‐to‐noise ratio of a mouse brain 13C CryoProbe™ system in comparison with room temperature coils: spectroscopic phantom and in vivo results

MRI and MRS in small rodents demand very high sensitivity. Cryogenic transmit/receive radiofrequency probes (CryoProbes) designed for ¹H MRI of mouse brain provide an attractive option for increasing the performance of small‐animal MR systems. As the Larmor frequency of ¹³C nuclei is four times lower than that for ¹H nuclei, an even larger sensitivity improvement is expected for ¹³C applications. The aim of this work was to evaluate the performance of a prototype ¹³C CryoProbe? for mouse brain MRS. To investigate the possible gain of the ¹³C CryoProbe?, we acquired localized single‐voxel ¹³C spectra and chemical shift images of a dimethyl sulfoxide phantom with the CryoProbe?, as well as with two room temperature resonators. The cryogenically cooled resonator achieved approximately four‐fold higher signal‐to‐noise ratio in phantom tests when compared with the best‐performing room temperature coil. In addition, we present localized ¹³C spectra of mouse brain obtained with the CryoProbe?, as well as with one of the room temperature coils, demonstrating the performance in vivo. In summary, the cryogenic cooling technique significantly enhances the ¹³C signal sensitivity at 9.4 T and enables the investigation of metabolism within mouse brain. Copyright © 2014 John Wiley & Sons, Ltd.     

Protective effect of carnosine on Cu,Zn-superoxide dismutase during impaired oxidative metabolism in the brain in vivo

Natural hydrophilic antioxidant carnosine protects cerebral cytosolic Cu,Zn-superoxide dismutase (SOD) under conditions of oxidative stress in various in vivo models: short-term hypobaric hypoxia in rats and accumulation of age-related changes in senescence-accelerated mice (SAMP). Administration of carnosine preventing Cu,Zn-SOD inactivation reduced mortality in rats and prolonged average life span in SAMP-mice.     

In vivo detection and automatic analysis of GABA in the mouse brain with MEGA‐PRESS at 9.4 T

The goals of this study were to develop an acquisition protocol and the analysis tools for Meshcher–Garwood point‐resolved spectroscopy (MEGA‐PRESS) in mouse brain at 9.4 T, to allow the in vivo detection of γ‐aminobutyric acid (GABA) and to examine whether isoflurane alters GABA levels in the thalamus during anesthesia. We implemented the MEGA‐PRESS sequence on a Bruker 94/20 system with ParaVision 6.0.1, and magnetic resonance spectra were acquired from nine male wild‐type C57BL/6 J mice at the thalamus. Four individual scans were obtained for each mouse in a 2‐h time course whilst the mouse was anesthetized with isoflurane. We developed an automated analysis program with improved correction for frequency and phase drift compared with the standard creatine (Cr) fitting‐based method and provided automatic quantification. During MEGA‐PRESS acquisition, a single voxel with a size of 5 × 3 × 3 mm³ was placed at the thalamus to evaluate GABA to Cr (GABA/Cr) ratios during anesthesia. Detection and quantitative analysis of thalamic GABA levels were successfully achieved. We noticed a significant decrease in GABA/Cr during the 2‐h anesthesia (by linear regression analysis: slope < 0, p < 0.0001). In summary, our findings demonstrate that MEGA‐PRESS is a feasible technique to measure in vivo GABA levels in the mouse brain at 9.4 T.     

Altered metabolites of the rat hippocampus after mild and moderate traumatic brain injury – a combined in vivo and in vitro 1H–MRS study

Traumatic brain injury (TBI) has been shown to affect hippocampus‐associated learning, memory and higher cognitive functions, which may be a consequence of metabolic alterations. Hippocampus‐associated disorders may vary depending on the severity of injury [mild TBI (miTBI) and moderate TBI (moTBI)] and time since injury. The underlying hippocampal metabolic irregularities may provide an insight into the pathological process following TBI. In this study, in vivo and in vitro proton magnetic resonance spectroscopy (¹H–MRS) data were acquired from the hippocampus region of controls and TBI groups (miTBI and moTBI) at D0 (pre‐injury), 4 h, Day 1 and Day 5 post‐injury (PI). In vitro MRS results indicated trauma‐induced changes in both miTBI and moTBI; however, in vivo MRS showed metabolic alterations in moTBI only. miTBI and moTBI showed elevated levels of osmolytes indicating injury‐induced edema. Altered levels of citric acid cycle intermediates, glutamine/glutamate and amino acid metabolism indicated injury‐induced aberrant bioenergetics, excitotoxicity and oxidative stress. An overall similar pattern of pathological process was observed in both miTBI and moTBI, with the distinction of depleted N‐acetylaspartate levels (indicating neuronal loss) at 4 h and Day 1 and enhanced lactate production (indicating heightened energy depletion leading to the commencement of the anaerobic pathway) at Day 5 in moTBI. To the best of our knowledge, this is the first study to investigate the hippocampus metabolic profile in miTBI and moTBI simultaneously using in vivo and in vitro MRS.     

Structural,functional, and biochemical changes in the brain during modeling of dopamine system disturbances in rats

Dysfunction of the dopamine system was modeled in Wistar rats by injection of 50 mg/kg L-dopa over 4 weeks. Experimental rats demonstrated considerably decreased locomotor activity and increased emotional strain compared to the control group. Structural changes consisted in a significant decrease in the size of neuronal bodies in the sensorimotor cortex (layers III and V) and caudate nucleus together with changed variability of these parameters compared to the corresponding values in the control. The neuroglial index increased by 22% in layer V, tended to decrease in layer III, and remained unchanged in the caudate nucleus. L-Dopa changed specific activity of enzymes: tyrosine hydroxylase activity in the sensorimotor cortex decreased by 25%, while monoamine oxidase B activity in the caudate nucleus increased by 33%. Thus, dysfunction of the dopamine system resulting in changes in dopamine metabolism not only leads to structural and functional rearrangements reducing functional capacities of the cell systems, but is also associated with compensatory and repair reactions in the brain. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No 7, pp. 39–41, July, 2007.     

Variations of serum eosinophil cationic protein and tryptase, measured in serum and saliva, during the course of immediate allergic reactions to foods

BACKGROUND: Subjective complaints and reactions after placebo administration during food challenges (FC) may make their outcome difficult to interpret. We determined serum ECP and tryptase as tryptase in saliva during FC, looking for markers to support challenge outcomes. METHODS: Twelve patients with systemic reactions after food intake and nine presenting oral allergy syndrome (OAS) underwent skin tests; total and specific IgE determination; double-blind, placebo-controlled FC (DBPCFC); and open challenges. Blood samples were collected before and 1, 2, and 5 h after challenge and saliva before and 5, 30, and 60 min after challenge. ECP and tryptase were quantified by ImmunoCAP (Pharmacia-Upjohn, Sweden). Serum tryptase of > 10 microg/l was considered positive. RESULTS: After positive DBPCFC (n = 8), ECP rose significantly (P < 0.05) at 1-h - 16.03 (12.8) microg/l (mean [standard deviation]) - and 2-h intervals - 17.56 (10.7) microg/l - compared to basal level of 9 (6.4) microg/l. After negative DBPCFC (n = 6), ECP increased from basal 9.63 (3.9) microg/l to 24.84 (14.17) microg/l at the 2-h time point. There were nonsignificant differences in ECP between patients with positive and negative FC. Two patients with positive challenge showed a tryptase level of >10 microg/l and only one patient with OAS showed 5.6 microg/l of tryptase 5 min after FC. CONCLUSIONS: ECP and tryptase in serum and saliva were not useful markers for FC outcomes.     

Study of the origin of short- and long-latency SSEP during recovery from brain ischemia in a rat model

Somatosensory evoked potentials (SSEPs) have been established as an electrophysiological tool for the prognostication of neurological outcome in patients with hypoxic–ischemic brain injury. The early and late responses in SSEPs reflect the sequential activation of neural structures along the somatosensory pathway. This study reports that the SSEP can be separated into early (short-latency, SL) and late (long-latency, LL) responses using independent component analysis (ICA), based on the assumption that these components are generated from different neural sources. Moreover, this source separation into the SL and LL components allows analysis of electrophysiological response to brain injury, even when the SSEPs are severely distorted and SL and LL components get mixed. With the help of ICA decomposition and corrected peak estimation, the latency of LL-SSEP is shown to be predictive of long-term neurological outcome. Further, it is shown that the recovery processes of SL- and LL-SSEPs follow different dynamics, with the SL-SSEP restored earlier than LL-SSEP. We predict that the SL- and LL-SSEPs reflect the timing of the progression of evoked response through the thalamocortical pathway and as such respond differently depending upon injury and recovery of the thalamic and cortical regions, respectively.     

In vitro,high‐resolution 1H and 31P NMR based analysis of the lipid components in the tissue,serum, and CSF of the patients with primary brain tumors: one possible diagnostic view

In vitro, high‐resolution ¹H and ³¹P NMR based qualitative and quantitative analyses of the lipid components of the tissue, serum, and CSF of patients with primary brain tumors were performed. Proton NMR spectra of the lipid extract of serum (blood specimen collected before the surgical procedure) and surgically discarded tissue showed that the total cholesterol (T.CHOL) and choline containing phospholipids (PL) were significantly higher in quantity in medulloblastoma and glioblastoma multiforme as compared to normal subjects. Serum lipid extracts of grade II/ III gliomas showed a higher quantity of PL than normal subjects. Cholestrol esters (CHOLest) were detectable in the tissue lipid extract of the patients with tumors and absent in normal tissue. There was a reduction in the quantity of CHOLest in the serum lipid extract of the tumor patients as compared to normal subjects. Ratio of PL to T.CHOL in serum lipid extract showed a significant difference between different grades of tumors versus normal subjects, while, a significant difference was observed only in medulloblastoma versus normal subjects in tissue lipid extract. Ratio of CHOL to CHOLest distinguishes the different grades of tumors versus normal subjects as well as between different grades of tumors (except medulloblastoma versus glioblastoma). The ratio of the Ph (total phospholipids except phosphatidylcholine) to PC (phosphatidylcholine) in ³¹P NMR based study showed a significant difference in all grades of tumors (except medulloblastoma) in normal subjects in tissue lipid extract as well as between different grades of tumors. Medulloblastoma could be differentiated from glioblastoma as well as from normal subjects in serum lipid extract by the ratio of the Ph to PC. Proton NMR spectra of the lipid extract of CSF showed that the CHOL, CHOLest, and PL were present in the patients with tumors, although these were absent in the patients with meningitis, motor neuron disease, and mitochondrial myopathies as well as in normal subjects. PL and T.CHOL provided discrimination between different grades of tumors (except glioblastoma versus medulloblastoma) in the lipid extract of the CSF. This study suggests the role of lipid estimation in CSF and serum as a complementary diagnostic tool for the evaluation of brain tumors preoperatively. NMR‐based lipid estimation of post‐surgical tumor tissue may also contribute to differentiating the tumor types. Copyright © 2009 John Wiley & Sons, Ltd.     

丁苯酞预处理对脑缺血再灌注损伤大鼠基质金属蛋白酶-9、基质金属蛋白酶组织抑制因子-1和血脑屏障的影响

目的:探讨丁苯酞预处理对脑缺血再灌注损伤大鼠基质金属蛋白酶-9(MMP-9)、基质金属蛋白酶组织抑制因子-1(TIMP-1)和血脑屏障的影响.方法:90只雄性SD大鼠随机分为假手术组,模型组,NBP预处理低剂量组、中剂量组、高剂量组.采用线栓法制作大脑中动脉栓塞(MCAO)模型,缺血2h再灌注24 h后以干湿重法测定脑组织含水量,伊文思蓝(EB)评估血脑屏障的破坏程度,实时PCR检测MMP-9及TIMP-1 mRNA的表达水平.结果:脑缺血再灌注后,脑组织含水量及EB含量明显增加,MMP-9和TIMP-1表达均增强,与假手术组比较差异有统计学意义.丁苯酞预处理各组脑组织含水量及EB含量较模型组明显下降,MMP-9表达显著减少,TIMP-1表达明显增加,丁苯酞预处理中、高剂量组差异无统计学意义.结论:丁苯酞预处理对脑缺血再灌注损伤大鼠可通过调节MMP-9/TIMP-1的表达,降低血脑屏障通透性,减轻脑水肿,发挥预防性保护作用.     

In humans IL-6 is released from the brain during and after exercise and paralleled by enhanced IL-6 mRNA expression in the hippocampus of mice

Aim: Plasma interleukin‐6 (IL‐6) increases during exercise by release from active muscles and during prolonged exercise also from the brain. The IL‐6 release from muscles continues into recovery and we tested whether the brain also releases IL‐6 in recovery from prolonged exercise in humans. Additionally, it was evaluated in mice whether brain release of IL‐6 reflected enhanced IL‐6 mRNA expression in the brain as modulated by brain glycogen levels. Methods: Nine healthy male subjects completed 4 h of ergometer rowing while the arterio‐jugular venous difference (a‐v diff) for IL‐6 was determined. The IL‐6 mRNA and the glycogen content were determined in mouse hippocampus, cerebellum and cortex before and after 2 h treadmill running (N = 8). Results: At rest, the IL‐6 a‐v diff was negligible but decreased to ?2.2 ± 1.9 pg ml^?1 at the end of exercise and remained low (?2.1 ± 2.1 pg ml^?1) 1 h into the recovery (P < 0.05 vs. rest). IL‐6 mRNA was expressed in the three parts of the brain with the lowest content in the hippocampus (P < 0.05) coupled to the highest glycogen content (3.2 ± 0.8 mmol kg^?1). Treadmill running increased the hippocampal IL‐6 mRNA content 2–3‐fold (P < 0.05), while the hippocampal glycogen content decreased to 2.6 ± 0.6 mmol kg^?1 (P < 0.05) with no significant changes in the two other parts of the brain. Conclusion: Human brain releases IL‐6 both during and in recovery from prolonged exercise and mouse data suggest that concurrent changes in IL‐6 mRNA and glycogen levels make the hippocampus a likely source of the IL‐6 release from the brain.     

Effect of litter quality on foot pad dermatitis,hock burns and breast blisters in broiler breeders during the production period

Foot pad dermatitis and hock burn lesions are a form of contact dermatitis, a condition affecting skin areas in contact with unsuitable or irritating material. Contact dermatitis is a common problem, reducing the welfare of broilers, and is believed to also affect broiler breeders. However, there is very little research on contact dermatitis in breeders. This study followed the severity of foot pad lesions in broiler breeders throughout the production period. At slaughter the presence of hock burns and breast blisters was also determined. In addition, changes in litter condition over time and the impact of litter quality on foot pads were evaluated. The study was performed on 10 broiler breeder farms, including altogether 18 flocks. Foot pads of 100 hens per flock were assessed at the end of rearing period, three times during the production period, and at slaughter. Foot pad and hock lesions, as well as litter condition were scored on a 5-point scale. Litter quality was evaluated as pH, moisture and ammonia content. The condition of foot pads deteriorated towards slaughter age, with the occurrence of severe lesions reaching a maximum of 64% on average at slaughter. Hock lesions and breast blisters were rare. The litter layer became drier over time. Although poorer litter condition and wetness influenced foot pad health negatively, the effect on severe lesions was not significant. We also observed a negative effect on foot pad condition of larger slat areas. In conclusion, maintaining good litter quality alone is not enough to ensure healthy foot pads in broiler breeders.     

A mechanism for the inactivation of Ca2+/calmodulin-dependent protein kinase II during prolonged seizure activity and its consequence after the recovery from seizure activity in rats in vivo

Seizure is a form of excessive neuronal excitation and seizure-induced neuronal damage has profound effects on the prognosis of epilepsy. In various seizure models, the inactivation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) occurs during seizure activity preceding neuronal cell death. CaMKII is a multifunctional protein kinase enriched in the brain and involved in various ways the regulation of neuronal activity. CaMKII inactivation during seizure activity may modify neuronal cell survival after seizure. However, the mechanism for CaMKII inactivation and its consequence after seizure recovery remain to be elucidated yet. In the present study, we employed a prolonged seizure model by systemic injection of kainic acid into rats and biochemically examined the activity state of CaMKII. In status epilepticus induced by kainic acid, not only the inactivation of CaMKII in brain homogenate, but also a shift in the distribution of CaMKII protein from the soluble to particulate fraction occurred in both hippocampus and parietal cortex. The particulate CaMKII showed a large decrease in the specific activity and a concurrent large increase in the autophosphorylation ratio at Thr-286 (alpha) and at Thr-287 (beta). In contrast, the soluble CaMKII showed normal or rather decreased specific activity and autophosphorylation ratio. After 24 h of recovery from kainic acid-induced status epilepticus, all such changes had disappeared. On the other hand, the total amount of CaMKII was decreased by 35% in hippocampus and 20% in parietal cortex, but the existing CaMKII was indistinguishable from those of controls in terms of the autonomous activity ratio, specific activity and autophosphorylation ratio. Thus, CaMKII inactivation in kainic acid-induced status epilepticus seems to be derived not from simple degradation of the enzyme, but from the formation of the autophosphorylated, inactivated and sedimentable CaMKII. Such a form of CaMKII may be important during pathological conditions in vivo in preventing excessive CaMKII activation due to Ca2+ overload.