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 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We used phosphorus magnetic resonance spectroscopy to assess in vivo the brain cytosolic free magnesium concentration and the free energy released by the reaction of adenosine triphosphate (ATP) hydrolysis (DeltaG(ATPhyd)), the latter being an index of the cell's bioenergetics condition. We studied 78 patients with migraine in attack-free periods (7 with migraine stroke, 13 with migraine with prolonged aura, 37 with migraine with typical aura or basilar migraine, and 21 with migraine without aura), and 13 patients with cluster headache. In the occipital lobes of all subgroups of migraine and in cluster headache patients cytosolic free [Mg(2+)] as well as the free energy released by the reaction of ATP hydrolysis were significantly reduced. Among migraine patients, the level of free energy released by the reaction of ATP hydrolysis and the cytosolic free [Mg(2+)] showed a trend in keeping with the severity of clinical phenotype, both showing the lowest values in patients with migraine stroke and the highest in patients with migraine without aura. These results support our current hypothesis that the reduction in free [Mg(2+)] in tissues with mitochondrial dysfunction is secondary to the bioenergetics deficit, and are against a primary role of low brain cytosolic free [Mg(2+)] in causing the bioenergetics deficit in headache.
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PMID:Deficient energy metabolism is associated with low free magnesium in the brains of patients with migraine and cluster headache. 1130 97

Malnutrition affects up to half of all chronic dialysis patients and is an important predictor of mortality, but the efficacy of interventions designed to improve the nutritional status of dialysis patients has been poorly studied. Specifically, although enteral tube feeding is often cited as an important option in the treatment of malnourished dialysis patients, there are few studies examining the effectiveness and complications of enteral tube feedings in adults on dialysis. We performed a retrospective analysis of a small cohort (n = 10) of chronic hemodialysis patients who received enteral tube feeding as all or part of their nutrition between January 1 and May 1, 1999, with follow-up through May 1, 2000, to assess the efficacy and complications of enteral tube feeding. Six patients received feeding via a peritoneoscopically placed (PEG) tube, 3 via nasogastric (NG) tube, and 1 patient was switched from PEG to NG feeding after an exit site infection developed at her PEG site. Seven patients received enteral feeding because of swallowing difficulties occurring after a cerebrovascular accident. Four patients were fed via enteral tube temporarily (</=4 months); the range of time on enteral feeding was 0.5 to 36 months. Five patients died by study end; only 1 recovered and no longer required enteral feeding. Patients were well dialyzed (median urea reduction rate, 73%). A significant improvement in serum albumin was seen (initial median albumin, 2.8, versus final median albumin, 3.4 g/dL, P =.04). Hypophosphatemia occurred in 8 of the 10 patients, and the nadir median phosphorus level was 1.95 mg/dL. One patient died as a result of an infected PEG. We conclude that enteral tube feeding is an important tool in the treatment of malnourished chronic hemodialysis patients and deserves formal study. Hypophosphatemia commonly occurs, and phosphorus levels should therefore be followed closely when initiating tube feedings in hemodialysis patients. In some cases, a nonrenal enteral formula may be useful for avoiding hypophosphatemia in these patients.
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PMID:Enteral tube feeding in a cohort of chronic hemodialysis patients. 1210 15

In the past decade, it has become possible to use the nuclear (proton, 1H) signal of the hydrogen atoms in water for noninvasive assessment of functional and physiological parameters with magnetic resonance imaging (MRI). Here we show that it is possible to produce pH-sensitive MRI contrast by exploiting the exchange between the hydrogen atoms of water and the amide hydrogen atoms of endogenous mobile cellular proteins and peptides. Although amide proton concentrations are in the millimolar range, we achieved a detection sensitivity of several percent on the water signal (molar concentration). The pH dependence of the signal was calibrated in situ, using phosphorus spectroscopy to determine pH, and proton exchange spectroscopy to measure the amide proton transfer rate. To show the potential of amide proton transfer (APT) contrast for detecting acute stroke, pH effects were noninvasively imaged in ischemic rat brain. This observation opens the possibility of using intrinsic pH contrast, as well as protein- and/or peptide-content contrast, as diagnostic tools in clinical imaging.
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PMID:Using the amide proton signals of intracellular proteins and peptides to detect pH effects in MRI. 1287 67

The purpose of the study was to compare nutrient intakes among Chinese, Japanese, UK, and US INTERMAP samples, and assess possible relationships of dietary patterns to differential patterns of cardiovascular diseases between East Asian and Western countries. Based on a common Protocol and Manuals of Operations, high-quality dietary data were collected by four standardized 24-h dietary recalls and two 24-h urine collections from 17 population samples in China (three samples), Japan (four samples), UK (two samples), and USA (eight samples). There were about 260 men and women aged 40-59 years per sample--total N=4680. Quality of dietary interview and data entry were monitored and enhanced by extensive systematic ongoing quality control procedures at local, country, and international level. Four databases on nutrient composition of foods from the four countries were updated and enhanced (76 nutrients for all four countries) by the Nutrition Coordinating Center, University of Minnesota, in cooperation with Country Nutritionists. The mean body mass index was much higher for Western than East Asian samples. Macronutrient intakes differed markedly across these samples, with Western diet higher in total fat, saturated and trans fatty acids, and Keys dietary lipid score, lower in total carbohydrate and starch, higher in sugars. Based on extensive published data, it is a reasonable inference that this pattern relates to higher average levels of serum total cholesterol and higher mortality from coronary heart disease in Western than East Asian populations. The rural Chinese diet was lower in protein, especially animal protein, in calcium, phosphorus, selenium, and vitamin A. Dietary sodium was higher, potassium lower, hence Na/K ratio was higher in the Asian diet, especially for Chinese samples. This pattern is known to relate to risks of adverse blood pressure level and stroke. At the end of the 20th century, East Asian and Western diets remain significantly different in macro- and micronutrient composition. Both dietary patterns have aspects that can be regarded, respectively, as adverse and protective in relation to the major adult cardiovascular diseases. In both Asian and Western countries, public efforts should be targeted at overcoming adverse aspects and maintaining protective patterns for prevention and control of cardiovascular diseases.
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PMID:Nutrient intakes of middle-aged men and women in China, Japan, United Kingdom, and United States in the late 1990s: the INTERMAP study. 1367 52

Age-related changes in hematological values, serum biochemical constituents, and weights of various organs in both sexes of the Spontaneously Hypertensive (SHR/Izm), Stroke-prone SHR (SHRSP/Izm), and Wistar Kyoto (WKY/Izm) rat strains, bred under SPF conditions, were examined to obtain fundamental data. The body weights from 3-30 weeks and systolic blood pressure from 6-30 weeks in each strain were measured every week. At the ages of 8, 16, and 30 weeks, the hematological values (erythrocyte, hemoglobin, hematocrit, leucocyte, thrombocyte), serum biochemical constituents (total protein, GOT, GPT, ALP, BUN, creatinine, glucose, total Ca and phosphorus, and ionized Ca, Na, K, and Cl were measured. Also, the organs, brain, heart, lung, thymus, liver, spleen, pancreas, bilateral kidneys, adrenal glands, testes/ovaries, digestive tract, and muscle (soleus) were weighed. The age-related changes as well as the strain and sex differences in each measured item were examined. The body weights of each strain increased, but rate of the increase was less in SHR and SHRSP, and was lowest in SHRSP. The blood pressure of SHR and SHRSP elevated with age, and showed higher in SHRSP than SHR, while that of WKY did not change. There were many strain differences in most measured items at each time point, particularly at 30 weeks. In SHRSP, high values of BUN, creatinine, total and ionized Ca, weights of brain, heart, liver, kidney and digestive duct were observed at most time points indicating that this strain's abnormality of calcium metabolism may be related to functions of the kidney and digestive duct as well as hypertension.
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PMID:Age-related changes in blood pressure, hematological values, concentrations of serum biochemical constituents and weights of organs in the SHR/Izm, SHRSP/Izm and WKY/Izm. 1499 46

Localized magnetic resonance spectroscopy (MRS) yields sensitive metabolic markers to provide insight into the pathophysiology of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) in vivo. Findings in full MELAS syndrome at 1H MRS of the brain typically include severely elevated lactate and reduced N-acetylaspartate, glutamate, myo-inositol, and total creatine concentrations in stroke-like lesions. Similar but less extreme alterations are also common in gray matter (GM) regions that appear normal at magnetic resonance imaging. Phosphorus spectroscopy of peripheral muscle permits investigation of the bioenergetic status. A decline of the phosphorylation potential indicates a low energy reserve at rest. Phosphocreatine resynthesis during post-exercise recovery is delayed pointing to reduced mitochondrial capacity. As MRS is inherently non-invasive, follow-up studies can be performed to assess treatment response quantitatively.
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PMID:Magnetic resonance spectroscopy in patients with MELAS. 1576 Jun 31

The 'classical' effects of vitamin D receptor activator or agonist (VDRA) therapy for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease primarily involves suppressive effects on the parathyroid gland, and regulation of calcium and phosphorus absorption in the intestine and mobilisation in bone. Observational studies in haemodialysis patients report improved cardiovascular and all-cause survival among those receiving VDRA therapy compared with those not on VDRA therapy. Among VDRAs, the selective VDRA paricalcitol has been associated with greater survival than nonselective VDRAs, such as calcitriol (1,25-dihydroxyvitamin D(3)). The survival benefits of paricalcitol appear to be linked, at least in part, to 'nonclassical' actions of VDRAs, possibly through VDRA-mediated modulation of gene expression. In cardiovascular tissues, VDRAs are reported to have beneficial effects such as anti-inflammatory and antithrombotic effects, inhibition of vascular smooth muscle cell proliferation, inhibition of vascular calcification and stiffening, and regression of left ventricular hypertrophy. VDRAs are also reported to negatively regulate the renin-angiotensin system, which plays a key role in hypertension, myocardial infarction and stroke. The selective VDRAs, paricalcitol and maxacalcitol, are associated with direct protective effects on glomerular architecture and antiproteinuric effects in response to renal damage. Paricalcitol regulates several cardiovascular and renal parameters more favourably than nonselective VDRAs. Complex nonclassical effects, which are not clearly understood, possibly contribute to the improved survival seen with VDRAs, especially paricalcitol.
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PMID:Nonclassical aspects of differential vitamin D receptor activation: implications for survival in patients with chronic kidney disease. 1788 84

Long-term bilateral common carotid occlusion (BCCAO) in rats induces brain hypoperfusion and structural injury, and could have relevance as a model of vascular dementia in which cortical metabolism is reduced. The present study was designed to assess whether phosphate-related energy compounds and blood supplies are markedly affected by KCI-induced cortical spreading depression (CSD), which leads to metabolic and cerebral blood flow changes in rats with chronic BCCAO, by means of near-infrared spectroscopy and phosphorus magnetic resonance spectroscopy. Male Wistar rats were divided into 4 groups: BCCAO for 1 week (n = 6) and 4 weeks (n = 15), and sham operation for 1 week (n = 7) and 4 weeks (n = 7). The phosphocreatine (Pcr) index (PCr/PCr+Pi) and intracellular pH (pHi) were measured pre-CSD, just after KCl application, and at 20 and 40 minutes after CSD. Brains were evaluated by histology with hematoxylin and eosin and immunohistochemical reaction for glial fibrillary acidic protein (GFAP). Rapid signal changes of oxy-, deoxy-, and total hemoglobin were observed in all KCl-applied brains. The PCr index and pHi values in BCCAO were not different than those in control rats. The percentage of vacuolated area in the optic tract and percentage values of GFAP-positive area in the frontoparietal cortex were significantly increased in BCCAO. The generation of CSD was seen in regions of cortical gliosis induced by BCCAO, and severe energy exhaustion did not occur during or after CSD. Our results may suggest that the functional interaction of neurons and glia is sustained even in brain tissue where the metabolic state of neurons is impaired and astrocytes are proliferated.
J Stroke Cerebrovasc Dis
PMID:Phosphate-related energy compounds are not exhausted in chronically hypoperfused rat brain cortex after cortical spreading depression. 1790 87

Plaque rupture is the most common type of plaque complication and leads to acute ischaemic events such as myocardial infarction and stroke. Calcification has been suggested as a possible indicator of plaque instability. Although the role of matrix vesicles in the initial stages of arterial calcification has been recognized, no studies have yet been carried out to examine a possible role of matrix vesicles in plaque destabilization. Tissue specimens selected for the present study represented carotid specimens obtained from patients undergoing carotid endarterectomy. Serial frozen cross-sections of the tissue specimens were cut and mounted on glass slides. The thickness of the fibrous cap (FCT) in each advanced atherosclerotic lesion, containing a well developed lipid/necrotic core, was measured at its narrowest sites in sets of serial sections. According to established criteria, atherosclerotic plaque specimens were histologically subdivided into two groups: vulnerable plaques with thin fibrous caps (FCT <100 microm) and presumably stable plaques, in which fibrous caps were thicker than 100 microm. Twenty-four carotid plaques (12 vulnerable and 12 presumably stable plaques) were collected for the present analysis of matrix vesicles in fibrous caps. In order to provide a sufficient number of representative areas from each plaque, laser capture microdissection (LCM) was carried out. The quantification of matrix vesicles in ultrathin sections of vulnerable and stable plaques revealed that the numbers of matrix vesicles were significantly higher in fibrous caps of vulnerable plaques than those in stable plaques (8.908+0.544 versus 6.208+0.467 matrix vesicles per 1.92 microm2 standard area; P= 0.0002). Electron microscopy combined with X-ray elemental microanalysis showed that some matrix vesicles in atherosclerotic plaques were undergoing calcification and were characterized by a high content of calcium and phosphorus. The percentage of calcified matrix vesicles/microcalcifications was significantly higher in fibrous caps in vulnerable plaques compared with that in stable plaques (6.705+/-0.436 versus 5.322+/-0494; P= 0.0474). The findings reinforce a view that the texture of the extracellular matrix in the thinning fibrous cap of atherosclerotic plaque is altered and this might contribute to plaque destabilization.
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PMID:Matrix vesicles in the fibrous cap of atherosclerotic plaque: possible contribution to plaque rupture. 1819 56

Increased vascular stiffness is an established risk marker of cardiovascular diseases (CVD) in adults with end-stage renal disease, but its role in pediatric patients remains to be defined. We prospectively examined arterial compliances of adolescents and young adults on hemodialysis (HD) using diastolic pulse wave analysis (DPWA). Each of the ten HD patients (age 17.3 +/- 3.9 years; mean +/- SD) had two DPWA tests within a three-week time period. DPWA measurement was performed before and hourly until the end of three-hour HD. Pre-HD large artery elasticity index (LAEI) was reduced in one patient and small artery elasticity index (SAEI) was reduced in another. Neither patient was hypertensive. Eight other patients had a reduction in both LAEI and SAEI. Among them, six patients had systolic and/or diastolic hypertension, and the other two were normotensive. Serum phosphorus correlated positively with stroke volume and cardiac output indices and negatively with SAEI. The reduction in BP during HD correlated with the amount of fluid removal. LAEI and SAEI were unchanged during HD. In conclusion, the reduction in LAEI and/or SAEI was observed in four normotensive patients, suggesting hypertension was not the only contributing factor for the reduced arterial compliances in our patients. The association between SAEI and serum phosphorus suggests that SAEI derived from DPWA can potentially be an early non-invasive, operator-independent, and volume-independent marker of CVD in adolescents and young adults receiving HD. Longitudinal studies with a larger sample size are needed to confirm our observation and speculation.
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PMID:Arterial compliance in adolescents and young adults receiving chronic hemodialysis. 1866 8


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