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PCr/Cr Ratio (cr + ratio)

Distribution by Scientific Domains

Medical Sciences	83%

Selected Abstracts

A study of the relationship between the seizure focus and 1H-MRS in temporal lobe epilepsy and frontal lobe epilepsy

PSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 4 2000
Senichiro Kikuchi MD
Abstract Several studies of temporal lobe epilepsy (TLE) patients have investigated the relationship between the seizure focus and 1H magnetic resonance spectroscopy (1H-MRS). There have also been a few reports in other types of partial epilepsy. We examined the relationship between the seizure focus and the reduction in N -acetylaspartate : creatine (NAA : Cr) ratio using 1H-MRS in both TLE and frontal lobe epilepsy (FLE) patients. We studied 21 patients with unilateral TLE and seven patients with unilateral FLE. We used a 1.5 Tesla magnetic resonance unit (Signa Horizon; General Electric). Approximately 15 × 15 × 20 mm3 voxel of interest (VOI) was placed over the anterior portion of the bilateral hippocampus in the TLE patients, and the anterodorsal position of bilateral frontal lobe in the FLE patients. The seizure focus was identified by interictal scalp electro-encephalogram (EEG). In the TLE patients the NAA : Cr ratios were reduced in the seizure focus, while in the FLE patients they were not always reduced in the seizure focus. In the TLE patients the coincidence rate between the seizure focus and the reduction in the NAA : Cr ratio was 90% (19 of 21 patients), while in the FLE patients the coincidence rate was only 57% (four of seven patients). [source]

Tibolone Exerts Its Protective Effect on Trabecular Bone Loss Through the Estrogen Receptor

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2001
A. G. H. Ederveen
Abstract Tibolone (Org OD14) has estrogenic, progestogenic, and/or androgenic activity depending on the tissue. In postmenopausal women, tibolone prevents bone loss without stimulating the endometrium. Tibolone is effective in preventing trabecular bone loss from the peripheral and axial skeleton of young and old ovariectomized (OVX) rats by reducing bone turnover, that is, bone resorption, like estrogens. We evaluated the contribution of the various hormonal activities to tibolone's bone-conserving effect. Three-month-old OVX rats received tibolone (125 ,g/rat or 500 ,g/rat, twice daily), alone or combined with an antiestrogen, antiandrogen, or antiprogestogen, and the effects on trabecular bone mass and bone turnover were evaluated. Sham-operated and control OVX groups were treated with vehicle. The remaining OVX groups received oral doses of tibolone twice daily, alone or with twice daily (a) antiestrogen ICI 164.384, (b) antiandrogen flutamide, or (c) antiprogestogen Org 31710. For comparison, the effects of 17,-estradiol and testosterone were examined also. After 4 weeks, trabecular bone mineral density (BMD) in the distal femur, plasma osteocalcin, and urinary deoxypyridinoline/creatinine ratio (Dpyr/Cr) were measured. Tibolone or 17,-estradiol significantly blocked ovariectomy-induced loss of trabecular BMD and inhibited bone resorption and bone turnover as judged by reduced Dpyr/Cr ratio and osteocalcin, respectively. These effects of both compounds were counteracted by the antiestrogen. This suggests a major involvement of the estrogen receptor in the action of tibolone on bone metabolism. However, the antiandrogen and the antiprogestogen did not counteract the effects of tibolone, excluding a major role of the androgenic and progestogenic activities of tibolone in its action against trabecular bone loss. The results indicate that tibolone acts on bone almost entirely through activation of the estrogen receptor. [source]

Usefulness of iodine/creatinine ratio from spot-urine samples to evaluate the effectiveness of low-iodine diet preparation for radioiodine therapy

CLINICAL ENDOCRINOLOGY, Issue 1 2010
Hee Kyung Kim
Summary Objective, The success of a low-iodine diet (LID) is best determined by measurement of 24-h urine iodine (U-I) excretion. The aim of this study was to determine reliable estimates for 24-h U-I based on spot-urine samples and to provide cut-offs to determine the effectiveness of LID preparation. Design, We prospectively measured iodine levels in 193 patients based on 24-h- and spot-urine samples before radioactive iodine therapy. The iodine was expressed as the 24-h U-I excretion (,g/day) and as two different indices from spot urine, simple iodine concentration (simple I) and the iodine/creatinine (I/Cr) ratio. Poor LID preparation was defined as I excretion of >150 ,g/day according to the 24-h U-I measurement. Results, The measured 24-h U-I was significantly higher than the two indices from spot urine (P < 0·001). However, there were statistically significant correlations between the 24-h U-I values and the two spot-urine-based indices; the correlation coefficient was 0·539 for simple I and 0·773 for I/Cr ratio (P < 0·001). The cut-off of I/Cr ratio for poor LID preparation was >66·2 ,g/g Cr (sensitivity 96·4%, specificity 83·6%, positive predictive value 50·0% and negative predictive value 99·3%). Conclusions, We demonstrated that the I/Cr ratio from spot urine could serve as a useful and reliable alternative to 24-h urine collection as it has acceptable diagnostic values for detecting poor LID preparation. [source]

Brain metabolism in rett syndrome: Age, clinical, and genotype correlations,

ANNALS OF NEUROLOGY, Issue 1 2009
Alena Horská PhD
Objective Brain metabolism, as studied by magnetic resonance spectroscopy (MRS), has been previously shown to be abnormal in Rett syndrome (RTT). This study reports the relation of MRS findings to age, disease severity, and genotype. Methods Forty RTT girls (1,14 years old) and 12 age-matched control subjects were examined. Single-voxel proton MRS of left frontal white matter was performed. Results NAA/Cr ratios decreased and myoinositol/Cr ratios increased with age in RTT patients (both p < 0.03), whereas these ratios were stable in control. The mean glutamate and glutamine/Cr ratio was 36% greater in RTT patients than in control (p = 0.043). The mean NAA/Cr ratio was 12.6% lower in RTT patients with seizures compared with those without seizures (p = 0.017). NAA/Cr ratios decreased with increasing clinical severity score (p = 0.031). Compared with patients with T158X, R255X, and R294X mutations, and C-terminal deletions, patients with the R168X mutation tended to have the greatest severity score (0.01 , p , 0.11) and the lowest NAA/Cr ratio (0.029 , p < 0.14). Interpretation Decreasing NAA/Cr and increasing myoinositol/Cr with age are suggestive of progressive axonal damage and astrocytosis in RTT, respectively, whereas increased glutamate and glutamine/Cr ratio may be secondary to increasing glutamate/glutamine cycling at the synaptic level. The relations between NAA/Cr, presence or absence of seizures, and disease severity suggest that MRS provides a noninvasive measure of cerebral involvement in RTT. Ann Neurol 2009;65:90,97 [source]

Bone resorption in infants of diabetic mothers

ACTA PAEDIATRICA, Issue 7 2005
Alexandre Lapillonne
Abstract Aim: Previous studies, using different techniques, have yielded contradictory findings concerning whether bone remodelling is altered in infants of diabetic mothers (IDM). The objective of the study was to assess the bone resorption of IDM during the first 3 mo of age. Methods: We conducted a longitudinal study using a specific index of bone resorption, urinary excretion of collagen type I cross-linked N-telopeptide (NTX), to compare bone resorption of a cohort of IDM and that of age-matched controls throughout the first 3 mo of life. Results: NTX/Cr ratio in IDM followed the same pattern over time as observed in control infants, i.e., a rapid increase during the first 10 d of life, a peak at 1 mo of life, and then a progressive decrease at 3 mo of life. There was no statistically significant difference between urinary NTX excretion observed in IDM and that observed in controls at any age studied. Conclusion: By using urinary NTX excretion, normal bone resorption was found in IDM throughout the first 3 mo of life. [source]

Neurochemical changes in the developing rat hippocampus during prolonged hypoglycemia

JOURNAL OF NEUROCHEMISTRY, Issue 3 2010
Raghavendra Rao
J. Neurochem. (2010) 114, 728,738. Abstract Hypoglycemia is common during development and is associated with the risk of neurodevelopmental deficits in human infants. The effects of hypoglycemia on the developing hippocampus are poorly understood. The sequential changes in energy substrates, amino acids and phosphocreatine were measured from the hippocampus during 180 min of insulin-induced hypoglycemia (blood glucose < 2.5 mmol/L) in 14-day-old rats using in vivo1H NMR spectroscopy. Hypoglycemia resulted in neuroglycopenia (brain glucose < 0.5 ,mol/g). However, the phosphocreatine/creatine (PCr/Cr) ratio was maintained in the physiological range until approximately 150 min of hypoglycemia, indicating that energy supply was sufficient to meet the energy demands. Lactate concentration decreased soon after the onset of neuroglycopenia. Beyond 60 min, glutamine and glutamate became the major energy substrates. A precipitous decrease in the PCr/Cr ratio, indicative of impending energy failure occurred only after significant depletion of these amino acids. Once glutamate and glutamine were significantly exhausted, aspartate became the final energy source. N -acetylaspartate concentration remained unaltered, suggesting preservation of neuronal/mitochondrial integrity during hypoglycemia. Correction of hypoglycemia normalized the PCr/Cr ratio and partially restored the amino acids to pre-hypoglycemia levels. Compensatory neurochemical changes maintain energy homeostasis during prolonged hypoglycemia in the developing hippocampus. [source]

Mechanism of the protective effect of hypothermia on ammonia toxicity in astrocytes

JOURNAL OF NEUROCHEMISTRY, Issue 2002
C. Zwingmann
Ammonia is a key factor in the pathogenesis of hepatic encephalopathy (HE). Acute ammonia treatment causes energy failure of astrocytes, which are able to compensate partly by increased anaerobic metabolism as a means of making up for the energetic shortfall. As hypothermia offers protection from severe encephalopathy and lactate accumulation in liver failure, we investigated the mechanism by which hypothermia protects against ammonia toxicity by multinuclear NMR spectroscopy. 12 h exposure to 5 mm NH4CL decreased the phosphocreatine (PCr)/creatine (Cr) and ATP/ADP ratios to 65 and 76% of control, increased synthesis and release of glutamine to 200,250% and led to a significant stimulation of glycolytic activity reflected by increased uptake and consumption of glucose and accumulation of de novo synthesized intra- and extracellular lactate to 161 and 230% of control. The protective effect of mild hypothermia was evident from inhibiton of lactate accumulation and restoration of ammonia-induced depletion of PCr/Cr. Moderate hypothermia led to an increase of PCr/Cr ratio and inhibited lactate synthesis to 14% of normothermic control, but did not prevent the ATP decrease. While hypothermia inhibited glycolytic flux, intracellular glutamine remained elevated. The results suggest that hypothermia-induced protection against ammonia toxicity results from reduction of cellular energy demand leading to inhibition of anaerobic glucose metabolism and a compensatory stimulation of mitochondrial energy production. Acknowledgements:, Funded by CIHR Canada. [source]

Brain metabolism in rett syndrome: Age, clinical, and genotype correlations,

Role of Proton Magnetic Resonance Spectroscopy in Differentiating Oligodendrogliomas from Astrocytomas

JOURNAL OF NEUROIMAGING, Issue 1 2010
Sanjeev Chawla PhD
ABSTRACT BACKGROUND AND PURPOSE Preoperative differentiation of astrocytomas from oligodendrogliomas is clinically important, as oligodendrogliomas are more sensitive to chemotherapy. The purpose of this study was to assess the role of proton magnetic resonance spectroscopy in distinguishing astrocytomas from oligodendrogliomas. METHODS Forty-six patients [astrocytomas (n= 17) and oligodendrogliomas (n= 29)] underwent magnetic resonance imaging and multi voxel proton magnetic resonance spectroscopic imaging before treatment. Peak areas for N-acetylaspartate (NAA), creatine (Cr), choline (Cho), myo-inositol (mI), glutamate/glutamine (Glx), and lipids + lactate (Lip+Lac) were analyzed from voxels that exhibited hyperintensity on fluid-attenuated inversion recovery images and were normalized to Cr from each voxel. The average metabolite/Cr ratios from these voxels were then compared between astrocytomas and oligodendrogliomas. Receiver-operating curve analyses were used as measures of differentiation accuracy of metabolite ratios. A threshold value for a metabolite ratio was estimated by maximizing the sum of sensitivity and specificity. RESULTS A significant difference in mI/Cr was observed between astrocytomas and oligodendrogliomas (.50 ± .18 vs. 0.66 ± 0.20, P < .05). Using a threshold value of .56 for mI/Cr ratio, it was possible to differentiate oligodendrogliomas from astrocytomas with a sensitivity of 72.4% and specificity of 76.4%. CONCLUSION These results suggest that mI/Cr might aid in distinguishing oligodendrogliomas from astrocytomas. J Neuroimaging 2010;20:3-8. [source]

MR Spectroscopy Findings in Lafora Disease

JOURNAL OF NEUROIMAGING, Issue 4 2009
Ebru Altindag MD
ABSTRACT PURPOSE Our aim was to investigate the [1H] MR spectroscopy (MRS) findings of Lafora Disease (LD), which is a disabling form of progressive myoclonic epilepsy. METHODS Twelve patients diagnosed with LD and 12 control subjects underwent MRS studies with single-voxels of 8 cc obtained in the frontal lobe, pons, and cerebellum. The metabolites and NAA/Cr, NAA/Cho, Cho/Cr, mI/Cr ratios were calculated. Subgroup analysis was also done between 5 patients with EPM2B and 6 patients with EPM2A mutations. Two investigators scored neurological symptom severity. RESULTS We found a statistically significant difference of NAA/Cho ratio in LD patients compared with normal controls in cerebellum (P= 0.04). In addition, both myoclonus and ataxia scores showed significant correlation with NAA/Cho ratios in the pons (P= 0.03, P= 0.04) and in the cerebellum (P= 0.04, P= 0.01), respectively. CONCLUSION We conclude that the cerebellum is the mostly affected structure in LD and there are significant correlations of MRS findings with some clinical parameters. The differences in the group may be related to different genetic mutations besides disease duration and other clinical variables. MRS studies could provide insights about the severity of the involvement of LD. [source]