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At least 109 records · Page 6Linked to original sources
PubMed1997

Fast spin-echo and fast fluid-attenuated inversion-recovery versus conventional spin-echo sequences for MR quantification of multiple sclerosis lesions.

PURPOSE: To compare fast spin-echo (FSE) and fast fluid-attenuated inversion recovery (FLAIR) sequences with conventional spin-echo (CSE) MR imaging in the quantification of the number and volume of multiple sclerosis lesions. METHODS: In 30 patients with relapsing-remitting multiple sclerosis, we calculated the total number and volume of lesions detected with each of the three sequences using a semiautomated program. RESULTS: On CSE sequences, we calculated a total of 2,583 lesions with a global volume of 836.3 cm3. With FSE sequences, we observed a 16% relative reduction in the number of lesions detected and a 25% relative reduction in global volume as compared with CSE. With fast FLAIR sequences, we detected a significantly lower number and volume of infratentorial lesions, whereas at the cortical/subcortical level the lesions were both more numerous and bulkier than on CSE sequences. Finally, we observed a higher lesion/white matter contrast, a significant reduction in time required for the quantification of lesion load, and a very low interobserver variability in favor of fast FLAIR sequences. CONCLUSION: Despite its limitations in the detection of infratentorial lesions, the fast FLAIR sequence in conjunction with a semiautomated quantification program provides a reliable means to evaluate the total lesion burden in patients with MS.

Adult↗
PubMed1995

Na channel density in extrajunctional sarcolemma of fast and slow twitch mouse skeletal muscle fibres: functional implications and plasticity after fast motoneuron transplantation on to a slow muscle.

Na channel densities were measured in fast and slow twitch mouse skeletal muscle fibres using the loose patch voltage clamp technique. It was found that Na channel density was approximately four times greater in fast twitch fibres than in slow. Computer simulations of action potential propagation in these fibres strongly suggest that the higher channel densities in fast twitch fibres are necessary to maintain action potential amplitude and fidelity of transmission across the neuromuscular junction, especially during the periods of rapid stimulation that these fibres are subjected to by their motoneurons. Transplantation of a foreign nerve containing axons which had previously innervated fast twitch fibres on to a slow twitch muscle resulted in an approximate doubling of the Na channel density in fibres innervated by the foreign nerve. These results suggest that motoneurons may exert considerable control over Na channel density in the muscle fibres they innervate.

Animals↗
PubMed2004

Drinking 300 mL of clear fluid two hours before surgery has no effect on gastric fluid volume and pH in fasting and non-fasting obese patients.

PURPOSE: To determine whether, in obese [body mass index (BMI) > 30 kg.m(2)] patients, oral intake of 300 mL clear liquid two hours before elective surgery affects the volume and pH of gastric contents at induction of anesthesia. METHODS: A single-blind, randomized study of 126 adult patients, age > or = 18 yr, ASA physical status I or II, BMI > 30 kg.m(2) who were scheduled for elective surgery under general anesthesia. Patients were excluded if they had diabetes mellitus, symptoms of gastroesophageal reflux, or had taken medication within 24 hr that affects gastric secretion, gastric fluid pH or gastric emptying. All patients fasted from midnight and were randomly assigned to fasting or fluid group. Two hours before their scheduled time of surgery, all patients drank 10 mL of water containing phenol red 50 mg. Those in the fluid group followed with 300 mL clear liquid of their choice. Immediately following induction of general anesthesia and tracheal intubation, gastric contents were aspirated through a multiorifice Salem sump tube. The fluid volume, pH and phenol red concentration were recorded. RESULTS: Median (range) values in fasting vs fluid groups were: gastric fluid volume 26 (3-107) mL vs 30 (3-187) mL, pH 1.78 (1.31-7.08) vs 1.77 (1.27-7.34) and phenol red retrieval 0.1 (0-30)% vs 0.2 (0-15)%. Differences between groups were not statistically significant. CONCLUSION: Obese patients without comorbid conditions should follow the same fasting guidelines as non-obese patients and be allowed to drink clear liquid until two hours before elective surgery, inasmuch as obesity per se is not considered a risk factor for pulmonary aspiration.

Adult↗
PubMedDate not supplied

Urinary excretion kinetics of intact quinidine and 3-OH-quinidine after oral administration of a single oral dose of quinidine gluconate in the fasting and non-fasting state.

To obtain more precise urinary excretion data of intact quinidine (D) and its main metabolite, 3-OH-quinidine (DM), the specific HPLC method of Bonora et al has been used to follow its urinary excretion kinetics. In a cross-over study, 2 commercial dosage forms of quinidine gluconate, fast- and slow-release, were administered to 18 healthy subjects who had fasted for 10 hours in 3 treatments which were administered during the fasting period (T1), and before (T2) of after (T3) a standard breakfast. The urine was collected at fixed time intervals for 72 hours after the administration of a single dose (405 mg of quinidine base). The difference between the drug release characteristics of the two products was studied by analysing the cumulative amount of D and DM excreted as a function of time, and the time required to reach the maximum value for the urinary excretion rate of intact quinidine. A food effect could be noticed among treatments with the conventional fast-release dosage form when comparing the maximum values of the urinary excretion rate of D (T2 greater than T1). There was no significant difference in the percentage of drug absorbed from the 2 products, according to the data on the cumulative amount of D and DM. The parameters estimated for quinidine and the metabolite were: the apparent half-life of elimination, the urinary excretion rates and the time to reach a maximum value in the urinary excretion rate. The urinary excretion rate constant and the renal clearance were also quantified for quinidine by combining urinary parameters with the corresponding serum data previously reported.

Administration, Oral↗
PubMed1988

Fatty acid metabolism of the perfused caudate lobe from livers of fed and fasted non-pregnant and fasted late pregnant ewes.

1. Fatty acid metabolism has been compared in perfused liver lobes from fed and fasted non-pregnant sheep and fasted pregnant sheep to provide further information on the control of ketogenesis in this species. 2. Ketogenesis from exogenous palmitate was greatest in lobes from fasted pregnant sheep and least in lobes from fed non-pregnant sheep, whereas rates of ketogenesis from exogenous octanoate (0.4 mM) were similar in lobes from sheep in all three states. 3. High rates of ketogenesis from endogenous fatty acids occurred in perfused lobes from fasted pregnant sheep, apparently owing to enhanced lipolysis. 4. Activities of glycerol-3-phosphate acyltransferase, carnitine palmitoyl transferase (CPT) and other enzymes involved in ketone production did not change with physiological state; sheep differ markedly from rats in this respect. 5. The results suggest that the primary point of control of ketogenesis within the liver of sheep is at the level of CPT; the lack of change in maximum CPT activity suggests that control by modulators of this enzyme activity is even more important in sheep than in rats.

Animals↗
PubMed2006

Impact of sugar beet pectin and polydextrose on fasting and postprandial glycemia and fasting concentrations of serum total and lipoprotein lipids in middle-aged subjects with abnormal glucose metabolism.

OBJECTIVE: To examine the effects of sugar beet pectin (SBP) and polydextrose (PDX) on fasting plasma glucose concentration, serum lipid profile and postprandial glycemia in middle-aged subjects with abnormal glucose metabolism. DESIGN: A placebo-controlled, randomized, parallel double-blinded study. SUBJECTS AND SETTING: Subjects were recruited via newspaper announcements. Seventy subjects were recruited of which 66 completed the study. INTERVENTION: The intervention period lasted for 12 weeks during which the subjects consumed a drink enriched with either SBP (n=22) or PDX (n=22) or without fiber enrichment (control group, n=22). The daily dose of the drinks was 4 dl. The subjects were also given nutrition counseling. Postprandial glycemia was examined in 24 subjects (n=8 in each group) at 0 and 12 weeks after a standardized breakfast. RESULTS: Fasting plasma glucose concentration did not change in the SBP and PDX groups, whereas it increased in the control group (P=0.007). On the contrary, the glycosylated hemoglobin A1(c) increased marginally but significantly (P< or =0.05) in the intervention groups without a change in the control group. In postprandial glycemia, no differences between the groups were found. In both the SBP and PDX groups, fasting serum High-density lipoprotein (HDL)-cholesterol concentration increased (P< or =0.05) without a change in the control group. Total to HDL-cholesterol ratio decreased in all groups (P< or =0.05). CONCLUSIONS: It was found that SBP and PDX do not have positive effects on fasting or postprandial plasma glucose concentrations or serum lipid profile in subjects with abnormal glucose metabolism.

Adult↗
PubMed1997

Intragastric pH after oral administration of single doses of ranitidine effervescent tablets, omeprazole capsules and famotidine fast-dissolving tablets to fasting healthy volunteers.

BACKGROUND: The therapeutic effect of drugs inhibiting acid production on acid-related discomforts is related to both the onset and duration of action of the drug. The effects on gastric pH by single oral doses of some acid-inhibiting drugs were investigated by measuring daytime (morning to lunch) intragastric pH in healthy volunteers. METHODS: This randomized, single-dose, 4-way crossover study included 15 healthy fasting subjects. Effervescent ranitidine tablets 150 and 300 mg, fast-dissolving famotidine tablets 20 mg and capsules of omeprazole 20 mg were administered. Measurements of intragastric pH were performed every 4 s for 10 min prior to drug administration and during the following 4 h. RESULTS: The effervescent ranitidine tablets (150 or 300 mg) produced similar changes in intragastric pH: following an immediate increase to about pH 5, intragastric pH decreased slightly over the next 10-20 min. Thereafter pH increased steadily, reaching pH 4 after 20-40 min and pH 6 after about 70 min. After famotidine, pH 4 was reached after 80 min, significantly slower than ranitidine. After omeprazole, pH 3 was never reached. Ranitidine 150 and 300 mg showed significantly larger integrated pH responses over the 4-h observation period, compared to famotidine (P = 0.0288 and 0.0074) or omeprazole (P < 0.001). CONCLUSIONS: After single-dose administration to healthy fasting volunteers), ranitidine effervescent tablets showed a significantly more rapid onset of action and a significantly larger integrated pH response compared to either famotidine 20 mg fast-dissolving tablets or omeprazole 20 mg capsules.

Administration, Oral↗
PubMed1994

Effects of fasting and 3,3',4,4',5,5'-hexabromobiphenyl on plasma transport of thyroxine and retinol: fasting reverses elevation of retinol.

Male Wistar rats were injected ip with 0 or 20 mg/kg 3,3',4,4',5,5'-hexabromobiphenyl and blood samples were collected 1, 3, 6, 7, and 8 d later. At 8 d after the injection, serum retinol was increased 30% and serum thyroxine was decreased 26% relative to control values. These effects were apparently unrelated to transthyretin in that the biphenyl did not alter the proportion of thyroxine binding in vitro to the prealbumin fraction of serum proteins. Separate groups of control and HBBP-injected rats did not receive food on d 7 (i.e., 24-h fast) and d 8 after injection (i.e., 48-h fast). Fasting decreased the serum retinol and thyroxine concentrations as well as the proportion of thyroxine binding in vitro to the prealbumin fraction of serum. The decreases in retinol and thyroxine concentrations associated with fasting are therefore ascribed to a decrease in the concentration of transthyretin in circulation.

Animals↗
PubMed1986

Ofloxacin: serum and skin blister fluid pharmacokinetics in the fasting and non-fasting state.

Using an agar well diffusion assay, the concentrations of ofloxacin were measured in serum and skin blister fluid after an oral dose of 300 mg given with or without a standardized meal. The apparent lag time was longer when the drug was taken with food than in the fasting state and the serum peak concentrations occurred later; the rates of absorption being 1.72 +/- 1.12/h (S.D.) and 3.40 +/- 1.56/h respectively. The mean peak concentrations of each individual in serum and blister fluid were 3.8 +/- 1.6 mg/l and 1.7 +/- 0.5 mg/l, respectively, when the drug was taken with food, compared with 4.2 +/- 1.9 mg/l and 2.1 +/- 0.7 mg/l in the fasting state. The rate of penetration into blister fluid was not influenced by the intake of food. The elimination half-life was 9.0 +/- 6.2 h in serum and 13.5 +/- 7.8 h in blister fluid when the volunteers were fasting. The corresponding values in the non-fasting state were 6.3 +/- 5.5 h and 10.6 +/- 4.6 h. The ratio of the area under the concentration versus time curve (AUC0-infinity) for blister fluid and serum was 1.20 +/- 0.70 when ofloxacin was given without food and 1.03 +/- 0.34 when given with the meal.

Adult↗
PubMed1975

Changes in fatty acid synthesis and lipogenic enzymes in adipose tissue from fasted and fasted-refed steers.

Controls of fatty acid synthesis in bovine adipose tissue were investigated. Six Brown Swiss steers were fasted for 8 days and then refed for 56 days. Biopsy samples of backfat adipose tissue were taken during the fasting and refeeding periods. Rates of acetate incorporation into fatty acids (FAS), activities of acetyl CoA carboxylase (CBX), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP:isocitrate dehydrogenase, and plasma free fatty acids (FFA) and plasma acetate were determined. FAS decreased 60% after 1 day of fasting and 99% after 8 days. FAS did not increase until day 3 of refeeding when energy intake was above maintenance, then returned to normal by 14 days. CBX followed a pattern similar to FAS, except its activity did rise above the control rate during refeeding. Plasma FFA increased 350% and acetate decreased 67% during fasting. After 4 days of refeeding, FFA returned to normal, and acetate increased to 156% of initial concentration, then returned to normal by 21 days. These data suggest that CBX limits FAS in adipose tissue of cattle.

Acetates↗
PubMed1984

Fasting and non-fasting serum amino acid values in three home parenteral nutrition patients: a comparison between Synthamin 17R and vamin N 7%R.

Serum amino acid concentrations were measured during the fasting and non-fasting stages of nutrition in three home parenteral nutrition patients who received their nitrogen requirement as Synthamin 17R for 12 months then Vamin N 7%R for 12 months. When the patients received Synthamin 17R, the fasting serum amino acid values revealed consistently elevated levels of glycine, phenylalanine, methionine and alanine and low levels of leucine, iso-leucine, valine, lysine, histidine, cystine and serine. When the patients received Vamin N 7%R, the fasting serum amino acid levels showed consistently elevated levels of proline, phenylalanine, glutamate, alanine, cystine and valine and low levels of arginine. Many of the serum amino acid abnormalities observed reflected the differences in the amino acid profiles of Vamin N 7%R and Synthamin 17R when compared with a normal diet.

Adult↗
PubMed2006

Pathogenesis of pre-diabetes: mechanisms of fasting and postprandial hyperglycemia in people with impaired fasting glucose and/or impaired glucose tolerance.

Thirty-two subjects with impaired fasting glucose (IFG) and 28 subjects with normal fasting glucose (NFG) ingested a labeled meal and 75 g glucose (oral glucose tolerance test) on separate occasions. Fasting glucose, insulin, and C-peptide were higher (P < 0.05) in subjects with IFG than in those with NFG, whereas endogenous glucose production (EGP) did not differ, indicating hepatic insulin resistance. EGP was promptly suppressed, and meal glucose appearance comparably increased following meal ingestion in both groups. In contrast, glucose disappearance (R(d)) immediately after meal ingestion was lower (P < 0.001) in subjects with IFG/impaired glucose tolerance (IGT) and IFG/diabetes but did not differ in subjects with IFG/normal glucose tolerance (NGT) or NFG/NGT. Net insulin action (S(i)) and insulin-stimulated glucose disposal (S(i)*) were reduced (P < 0.001, ANOVA) in subjects with NFG/IGT, IFG/IGT, and IFG/diabetes but did not differ in subjects with NFG/NGT or IFG/NGT. Defective insulin secretion also contributed to lower postprandial R(d) since disposition indexes were lower (P < 0.001, ANOVA) in subjects with NFG/IGT, IFG/IGT, and IFG/diabetes but did not differ in subjects with NFG/NGT and IFG/NGT. We conclude that postprandial hyperglycemia in individuals with early diabetes is due to lower rates of glucose disappearance rather than increased meal appearance or impaired suppression of EGP, regardless of their fasting glucose. In contrast, insulin secretion, action, and the pattern of postprandial turnover are essentially normal in individuals with isolated IFG.

Blood Glucose↗
PubMed1988

Influence of fasting and post-fast diet energy level on feed intake, feeding pattern and blood variables of lambs.

Trials were conducted to determine the influence of feed and water deprivation on feed intake, plasma glucose, free fatty acids (FFA), urea-N (PUN), serum insulin and growth hormone (GH) in lambs. In Trial 1, 12 Hampshire X Suffolk lambs (avg wt 30.5 kg) were deprived of feed and water for 0, 24, 48 or 72 h. During the first 8 d of realimentation, feed intake was depressed more (P less than .05) by longer periods of deprivation. In Trial 2, 12 crossbred lambs (avg wt 50 kg) were deprived of feed and water for 0 or 72 h. During the first 4 d of realimentation, feed intake was lower (P less than .05) in deprived than in fed lambs. The depressed feed intake could be detected within 30 min of feeding. In Trial 3, 12 crossbred lambs (avg wt 40 kg) were fasted for 0 or 72 h, and blood samples were obtained at -5, 30, 60, 120 and 180 min postprandial. On the 1st d of realimentation, lambs previously fasted had abnormal serum hormone patterns compared with nonfasted controls. On d 2 of realimentation, lambs previously fasted had higher (P less than .05) insulin, glucose and FFA than controls. On d 4 of realimentation, lambs previously fasted had higher insulin:GH ratios and lower PUN than controls. Results of these trials suggest that depriving lambs of feed and water for 72 h reduces subsequent feed intake for 4 d or more. Postprandial blood metabolite patterns are abnormal for a similar length of time.

Animals↗
PubMed1986

Degeneration-regeneration as a mechanism contributing to the fast to slow conversion of chronically stimulated fast-twitch rabbit muscle.

Extensor digitorum longus muscles of male adult White New Zealand rabbits were indirectly stimulated at 10 Hz for 12 h daily for periods ranging up to 28 days. After four weeks the stimulated muscles showed a nearly uniform profile of high succinate dehydrogenase activity and, when incubated after acid preincubation for myofibrillar adenosine triphosphatase, displayed more dark- and intermediate-staining fibers than their contralateral counterparts. Muscles stimulated from between 6 to 21 days revealed degenerative foci and phagocytosis of degenerated fibers. These fibers were mostly of the fast-twitch, glycolytic type. Small myofibers, which often contained central nuclei, and structures identified as myoblasts or myotubes, reacted with a monoclonal antibody prepared against embryonic myosin heavy chains. The data suggest that under the employed conditions the fast to slow conversion of chronically stimulated fast-twitch rabbit muscle is not exclusively caused by adult fiber transformation, but results in part from the substitution of fast-twitch glycolytic fibers with newly formed fibers that have a high oxidative profile.

Adenosine Triphosphatases↗
PubMed2005

Fast-track DRESSA: a bioassay for fast, sensitive, and selective detection of halogenated and polycyclic aromatic hydrocarbons.

Dioxin and related chemicals cause a variety of toxic and biological effects via the aryl hydrocarbon receptor (AhR). We recently reported a mammalian cell-based bioassay system (dioxin-responsive-element-based sensing via secreted alkaline phosphatase; DRESSA) that can detect dioxin and dioxin-like chemicals with high sensitivity. In this report, we describe an advanced method (designated "fast-track DRESSA") that achieves fast, selective, and sensitive detection of dioxin and other toxic compounds. By optimization of assay conditions on cell number and serum concentration, the fast-track DRESSA enabled detection of 0.5 pM 2,3,7,8-tetrachlorodibenzo-p-dioxin within 6 h. It also enabled detection of 10 pM 3-methylcholanthrene, 100 pM benzo[a]pyrene, and 100 pM beta-naphthoflavone within 6-16 h. By combination with the AhR antagonist alpha-naphthoflavone, nonspecific, false-positive responses could be eliminated. Because of its time-saving property and easiness, sensitiveness, and specificity, the fast-track DRESSA would be advantageous for high-throughput screening of dioxin and dioxin-like compounds in environmental samples.

Alkaline Phosphatase↗
PubMed1998

3D fast FLAIR: a CSF-nulled 3D fast spin-echo pulse sequence.

Since its introduction, the fluid attenuated inversion recovery (FLAIR) sequence has found many applications in the central nervous system (CNS), because of its heavy T2 weighting and excellent cerebrospinal fluid (CSF) suppression. More recently fast spin-echo based variants have been developed that greatly reduce scan time; such sequences are often referred to as "fast FLAIR." We present what we believe to be the first implementation of FLAIR using a three dimensional (3D) fast spin-echo-based pulse sequence, which combines the cerebrospinal fluid suppression and good lesion contrast of two-dimensional fast FLAIR with the advantages of a three-dimensional sequence such as higher signal-to-noise ratio (SNR) per unit time, thinner slices (giving reduced partial volume effect) and the ability to reformat the data in an arbitrary plane.

Brain↗
PubMed2003

Fast rotational matching of rigid bodies by fast Fourier transform acceleration of five degrees of freedom.

The 'fast rotational matching' method (an approach to find the three rotational degrees of freedom in matching problems using just one three-dimensional FFT) is extended to the full six-dimensional (rotation and translation) matching scenario between two three-dimensional objects. By recasting this problem into a formulation involving five angles and just one translational parameter, it was possible to accelerate, by means of fast Fourier transforms, five of the six degrees of freedom of the problem. This method was successfully applied to the docking of atomic structures of components into three-dimensional low-resolution density maps. Timing comparisons performed with our method and with 'fast translational matching' (the standard way to accelerate the translational parameters utilizing fast Fourier transforms) demonstrates that the performance gain can reach several orders of magnitude, especially for large map sizes. This gain can be particularly advantageous for spherical- and toroidal-shaped maps, since the scanning range of the translational parameter would be significantly constrained in these cases. The method can also be harnessed to the complementary surface (or 'exterior docking') problem and to pattern recognition in image processing.

Fourier Analysis↗
PubMed2001

Calcineurin regulates slow myosin, but not fast myosin or metabolic enzymes, during fast-to-slow transformation in rabbit skeletal muscle cell culture.

The addition of cyclosporin A (500 ng ml(-1)) - an inhibitor of the Ca2+-calmodulin-regulated serine/threonine phosphatase calcineurin - to primary cultures of rabbit skeletal muscle cells had no influence on the expression of fast myosin heavy chain (MHC) isoforms MHCIIa and MHCIId at the level of protein and mRNA, but reduced the expression of slow MHCI mRNA. In addition, no influence of cyclosporin A on the expression of citrate synthase (CS) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA was found. The level of enzyme activity of CS was also not affected. When the Ca2+ ionophore A23187 (4 x 10(-7) M) was added to the medium, a partial fast-to-slow transformation occurred. The level of MHCI mRNA increased, and the level of MHCIId mRNA decreased. Cotreatment with cyclosporin A was able to prevent the upregulation of MHCI at the level of mRNA as well as protein, but did not reverse the decrease in MHCIId expression. The expression of MHCIIa was also not influenced by cyclosporin A. Cyclosporin A was not able to prevent the upregulation of CS mRNA under Ca2+ ionophore treatment and failed to reduce the increased enzyme activity of CS. The expression of GAPDH mRNA was reduced under Ca2+ ionophore treatment and was not altered under cotreatment with cyclosporin A. When the myotubes in the primary muscle culture were electrostimulated at 1 Hz for 15 min periods followed by pauses of 30 min, a partial fast-to-slow transformation was induced. Again, cotreatment with cyclosporin A prevented the upregulation of MHCI at the level of mRNA and protein without affecting MHCIId expression. The nuclear translocation of the calcineurin-regulated transcription factor nuclear factor of activated thymocytes (NFATc1) during treatment with Ca2+ ionophore, and the prevention of the translocation in the presence of cyclosporin A, were demonstrated immunocytochemically in the myotubes of the primary culture. The effects of cyclosporin A demonstrate the involvement of calcineurin-dependent signalling pathways in controlling the expression of MHCI, but not of MHCIIa, MHCIId, CS and GAPDH, during Ca2+ ionophore- and electrostimulation-induced fast-to-slow transformations. The data indicate a differential regulation of MHCI, of MHCII and of metabolism. Calcineurin alone is not sufficient to mediate the complete transformation.

Animals↗