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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Various approaches estimating local cerebral glucose utilization by positron emission tomography of labeled deoxyglucose are compared. Autoradiographic methods that predict the glucose utilization rate from a single scan are unreliable in pathologic tissue because of abnormal values of the model rate constants. A normalization procedure using the ratio of measured tissue activity to activity calculated with standard rate constants is proposed to readjust the values of the rate constants. Reliable estimates of metabolic rates can be obtained from dynamic recordings of tracer uptake. In the graphic approach, metabolic rate can be derived from the slope of a segment of a transformed uptake curve, which becomes linear at 15-20 min after intravenous tracer injection, with an accuracy comparable with that in complete dynamic studies. However, by recording and analyzing full-length uptake curves, in addition to metabolic rate, the model rate constants can be determined regionally. The physiological significance of those parameters is demonstrated in crossed cerebellar deactivation in 30 patients with supratentorial infarcts. Mild hypometabolism both within the ischemic lesion and in the morphologically intact cerebellum is accompanied by a reduction of the phosphorylation rate only. Severe metabolic depression, by contrast, affects both cerebellar transport and phosphorylation processes, whereas in the cerebrum, only the rate constant k1 is significantly correlated with the degree of metabolic disturbance.
J Cereb Blood Flow Metab 1985 Mar
PMID:Estimation of local cerebral glucose utilization by positron emission tomography of [18F]2-fluoro-2-deoxy-D-glucose: a critical appraisal of optimization procedures. 387 80

A review and a reappraisal are presented of earlier data on cerebral circulatory and metabolic studies in normal active elderly men (Group I) of mean age 71 years, compared with normal young subjects of mean age 21 years, conducted at the National Institutes of Health, Bethesda, MD, U.S.A., during 1956-1958. There was no significant difference in the mean CBF and cerebral metabolic rate for oxygen (CMRO2) values between the two populations; i.e., these important parameters did not fall with chronological aging per se. There was significant depression in the mean cerebral metabolic rate for glucose (CMRG) value (by approximately 23%) in the aged compared with the young. Newer methods using positron emission tomography and appropriate isotopes have confirmed these findings in normal aging in human subjects and experimental animals. As expected, MABP and cerebral vascular resistance (CVR) were significantly elevated in the normal aged. MABP was even more elevated in elderly hypertensive subjects, and the CVR more elevated in the subjects with arteriosclerosis (Group II), who also showed a small but significant fall in CBF and in internal jugular venous PO2. The CBF showed a more pronounced fall in senile aged patients with chronic brain syndrome (Group III), in whom the CMRO2 also showed a marked drop (by approximately 22%); the CMRG fell still further (approximately 40% of that in the young). Of the few aged subjects followed up after a lapse of 11 years by a repeat estimation of the same physiological and psychological parameters and of the EEG, most showed clear worsening, together with a fall in overall physical and intellectual performance, probably related to a rise in CVR and an increase in atherosclerosis with aging.(ABSTRACT TRUNCATED AT 250 WORDS)
J Cereb Blood Flow Metab 1985 Mar
PMID:Cerebral blood flow and metabolism in normal human aging, pathological aging, and senile dementia. 397 14

The objective of the study was to estimate changes in extracellular pH (pHe) and intracellular pH (pHi) during seizures and in the recovery period following the arrest of seizure activity. Seizures of 5- and 20-min duration were induced in rats by fluorothyl added to the insufflated gas mixture, and recovery for 5, 15, and 45 min was instituted by withdrawal of the fluorothyl supply following 20 min of continuous seizures. Changes in pHe were measured by double-barreled, liquid ion-exchange pH microelectrodes, and in pHi by the CO2 method, following estimation of tissue PCO2 and extracellular fluid (ECF) volume. The animals were either normoxic or rendered moderately hypoxic (arterial PO2 40-50 mm Hg). Upon induction of seizures in normoxic animals, pHe decreased by a mean of 0.36 unit, the values being identical at 5 and 20 min. In moderate hypoxia, seizures sustained for 20 min were accompanied by a further fall in pHe (mean decrease 0.51 unit). The changes in pHe seemed mainly to reflect the nonionic diffusion of lactic acid from cells to the ECF (tissue lactate levels approximately 10 and 15 mumol g-1 during seizures in normoxic and hypoxic animals, respectively). However, the gradual fall in pHe attributable able to lactic acid production was preceded by rapid acidification, sometimes exceeding the steady-state values subsequently attained. This acidification was interpreted to reflect spreading depression and fast transcellular Na+/H+ exchange. Following cessation of seizure discharge, pHe normalized at a surprisingly slow rate, with some acidosis persisting even after 45 min. The difference between cerebrovenous and arterial PCO2 was reduced during seizures and increased in the recovery period, probably reflecting alterations in the blood flow/metabolic rate coupling. Impedance changes were slight, indicating only minor changes in ECF volume. Changes in pHi after 5 min of seizures ranged from 0.20 (normoxic animals) to 0.32 (hypoxic animals) unit, the pHi values after 20 min being 0.07-0.08 unit higher. The results suggest the regulation of pHi during ongoing seizures. Upon arrest of seizure activity, pHi rapidly increased to normal and subsequently to supranormal values. Postepileptic intracellular alkalosis occurred at a time when pHe was still reduced and in spite of the fact that tissue lactate values had not normalized. It is concluded that the rapid normalization of pHi and overt alkalosis were caused by the simultaneously occurring oxidation of lactate, with the removal of a stoichiometrical amount of H+, and the extrusion of H+ from cells, possibly via a Na+/H+ exchanger, the latter probably delaying normalization of pHe.
J Cereb Blood Flow Metab 1985 Mar
PMID:Extra- and intracellular pH in the brain during seizures and in the recovery period following the arrest of seizure activity. 397 23

The regional flow-metabolism couple was studied during the recovery period after 1 h of left middle cerebral artery (MCA) occlusion in cats. Local CBF (LCBF) was assessed at the end of ischemia as well as at the end of 4 h of recirculation by the microsphere technique. Local CMRgl (LCMRgl) was measured at the end of the recirculation period with [14C]2-deoxyglucose. Histology was evaluated by light microscopy from coronal brain blocks adjacent to those used for the determination of LCBF and LCMRgl. When LCBF in the central and peripheral MCA territories during the recovery period was between 40 and 115% of the value in sham occlusion studies, LCMRgl was greater than the control level found in the sham studies, and was accompanied by slight histological damage. This finding suggests that anaerobic glycolysis may persist after transient ischemia in spite of the recovery of LCBF to a level that is normally greater than the threshold for the activation of anaerobic glycolysis (less than 40% of the control). Persistent anaerobic glycolysis in the reperfusion period following an ischemic insult may be a sign of early tissue damage. Some of the regions in the peripheral MCA territory with LCBF between 40 and 110% of the levels during the recovery period in the sham studies showed a mild to moderate depression in LCMRgl so that the flow-metabolism ratio remained normal. These regions did not exhibit histological damage. This possible protective mechanism of the tissue in response to ischemia is discussed from the standpoint of the relationship between flow and metabolism.
J Cereb Blood Flow Metab 1985 Jun
PMID:Regional flow-metabolism couple following middle cerebral artery occlusion in cats. 398 23

The effect of iodoacetate (IAA), an inhibitor of glycolysis, on local CBF (LCBF) and local CMRglu (LCMRglu) was studied in cats by means of a double-radionuclide autoradiographic method. Artificial CSF containing 5 mM IAA was superfused on the left parietal cortex under a cranial window for 30 min. [14C]2-Deoxyglucose and [123I]iodoantipyrine were injected for the determination of LCMRglu and LCBF, respectively. A marked increase in LCBF, accompanied by a moderate to severe depression of LCMRglu, was observed in the IAA-superfused cortex. This result suggests that LCBF may be closely regulated by the cellular energy state associated with glycolytic activity in brain tissue.
J Cereb Blood Flow Metab 1985 Jun
PMID:Effect of iodoacetate on local cerebral blood flow and glucose metabolism in cats: a double-radionuclide autoradiographic study. 398 28

In vivo incorporation of choline-methyl-(14)C into liver lecithin and its biosynthetic precursors was studied in CCl(4)-treated rats. Radioactivity in cytidine diphosphoryl (CDP-)choline and lecithin was reduced to one-third of control levels, whereas that of phosphorylcholine was increased to 4.7 times control levels. Incorporation of phosphorylcholine-(32)P into lecithin by homogenates prepared from livers of CCl(4)-treated animals was reduced, but conversion of CDP-choline-(32)P to lecithin by the isolated microsomal fraction did not show any significant depression. A block in the synthesis of CDP-choline is indicated. The in vivo utilization of methionine for lecithin synthesis was not affected. After intravenous injection of palmitic acid-1-(14)C, radioactivity of triglycerides from microsomal and mitochondrial fractions was markedly lower than the controls, whereas radioactivity of triglycerides in the soluble fraction was greatly increased. Radioactivity of diglycerides changed from 0.5% of total lipids in the control to 10% of total lipids in CCl(4)-treated animals. Incorporation of palmitic acid into phospholipids was also suppressed. The results demonstrate that synthesis of both phospholipids and triglycerides is inhibited in rats 4-5 hr after CCl(4) administration.
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PMID:Effect of carbon tetrachloride administration on the synthesis of triglycerides and phospholipids in rat liver. 580 22

Local cerebral glucose utilization (LCGU) and local cerebral blood flow (LCBF) were studied by autoradiographic techniques in indomethacin- and ibuprofen-treated rats with focal cortical freezing lesions. Widespread depression of LCGU, which developed with time after the lesion in untreated animals was significantly diminished by the prostaglandin synthetase inhibitors indomethacin (single injection 7.5 mg/kg) and ibuprofen (36 mg/kg/day). Both drugs were effective when given 6 h before or up to 24 h after the lesion was made. The effect of the drugs was most striking in cortical areas of the traumatized hemisphere, where the depression was most profound in untreated animals. Thus, 3 days after the lesion, average LCGU in these regions was 46%, 86%, and 98% of normal in untreated, indomethacin-pretreated, and ibuprofen-pretreated rats, respectively. Prostaglandin formation was completely inhibited in the lesion area in the indomethacin-treated rats (PGF2 alpha 1.8 ng/g, compared to 57.5 ng/g in untreated and 1.4 ng/g in nonlesioned animals). The results suggest that some components of the prostaglandin system are involved in mechanisms underlying a widespread depression in functional state of the rat brain that develops in response to injury. In control animals, indomethacin was shown to have a biphasic effect on LCBF, an early depression shown previously by others followed at 24 h by a considerable increase.
J Cereb Blood Flow Metab 1983 Dec
PMID:Effects of indomethacin and ibuprofen on cerebral metabolism and blood flow in traumatized brain. 641 77

The purpose of the present study was to examine the cerebral perfusion after spreading depression with special emphasis on its relation to the perfusion changes in migraine. The cerebrovascular reactivity to changes of arterial PCO2 tension in the range of 24-70 mm Hg and to changes of MABP in the range of 55-150 mm Hg was studied in the rat brain after one episode of cortical spreading depression. Regional CBF (rCBF) was measured in the frontal, parietal, and occipital cortex, the basal ganglia, and the cerebellum of both hemispheres after the intravenous bolus injection of [14C]iodoantipyrine. rCBF decreased in the cortical regions to 69-73% of control values for 1 h after spreading depression in every single rat, but remained unchanged in the basal ganglia and cerebellum. CBF changed with alterations of arterial carbon dioxide tension in all brain regions. In control regions, CBF changed by 2.8-3.9% per mm Hg PaCO2 change, whereas in the spreading depression cortex, CBF changed by only 1.3-1.5%. The difference between control and spreading depression cortex was significant at p less than 0.001, indicating a reduced CO2 sensitivity of the cortical regions invaded by spreading depression. rCBF remained unchanged in all brain regions in the MABP range of 80-150 mm Hg, reflecting the intact autoregulatory function of the two sides, and at a MABP of less than 80 mm Hg, rCBF decreased in parallel in symmetrical regions. It is concluded that the hypoperfusion after spreading depression is due to a vasoconstrictor stimulus overriding the vasodilatory effect of acid pH.(ABSTRACT TRUNCATED AT 250 WORDS)
J Cereb Blood Flow Metab 1984 Dec
PMID:Long-lasting reduction of cortical blood flow of the brain after spreading depression with preserved autoregulation and impaired CO2 response. 643 24

With the use of positron emission tomography (PET) and the 15O steady-state-[18F]fluorodeoxyglucose combined method, the local interrelationships between the cerebral metabolic rate for oxygen (CMRO2) and the cerebral metabolic rate for glucose ( CMRGlc ) were investigated in control subjects and in stroke patients. In addition to the classic in vivo autoradiographic approach, a kinetic method was used to measure CMRGlc because it was expected to be more reliable in cerebral ischemia. In control subjects local coupling between CBF, CMRO2, and CMRGlc was confirmed, and acceptable values for the CMRO2/ CMRGlc ratio were found; the latter, however, was lower in white matter than in gray. Uncoupling between CMRO2 and CMRGlc was observed in all stroke patients, suggesting that (1) enhanced anaerobic glycolysis occurred both in reperfused recent infarcts and in chronically ischemic tissue, and (2) substrates other than blood-borne glucose were being oxidized at the borders of recent infarcts. However, methodological uncertainties presently make such observations only tentative. Finally, a coupled depression of CMRO2 and CMRGlc was found in the contralateral cerebellum.
J Cereb Blood Flow Metab 1984 Jun
PMID:Local interrelationships of cerebral oxygen consumption and glucose utilization in normal subjects and in ischemic stroke patients: a positron tomography study. 660 28

Seventy measurements of CBF were performed in 12 stroke patients by 133Xe inhalation and a rapidly rotating single photon emission computerized tomograph. CBF was measured every other day during the acute phase and at 2- and 6-month follow-up visits. A persistent contralateral cerebellar blood flow depression was evident in five patients with severe hemispheric low flow areas, which correlated with large, hypodense lesions on the computerized tomographic scan. In a sixth patient with a small, deep infarct, a transient crossed cerebellar low flow was observed, while the clinical symptoms persisted. It is concluded from this serial study that crossed cerebellar diaschisis is a common finding in completed stroke. It is probably caused by disconnection of the corticopontine pathways, a disconnection that tends to persist. The phenomenon is in fact less variable than the stroke-related CBF changes in the infarcted hemisphere, in which a period of relative hyperemia is frequently seen.
J Cereb Blood Flow Metab 1984 Jun
PMID:Crossed cerebellar diaschisis in ischemic stroke: a study of regional cerebral blood flow by 133Xe inhalation and single photon emission computerized tomography. 660 30


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