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At least 127 records · Page 7Linked to original sources
PubMed1984

Effects of fast and slow patterns of tonic long-term stimulation on contractile properties of fast muscle in the cat.

Different physiological rates of 'tonic' long-term electrical stimulation (rates 5-40 Hz; activity greater than or equal to 50% total time) were delivered to the left-side common peroneal nerve of the cat hind limb. The duration of treatment was 8 weeks, and the animals had previously been subjected to a left-side hemispinalization and dorsal rhizotomy. In the absence of stimulation, these operations had no slowing or weakening effects on peroneal muscle contraction. The minimum two-pulse interval that gave a summation of tension (neuromuscular refractory period) was longer for stimulated than for non-stimulated muscles. Twitches of chronically stimulated muscles had become prolonged by more than 100%. Corresponding changes were found in the tension-frequency relation and in the 'sag'-behaviour of the stimulated muscles. There were no differences between the 'fast' (20 or 40 Hz pulse rates) and the 'slow' (5 or 10 Hz pulse rates) patterns of tonic stimulation with respect to their effects on speed-related muscle properties. Furthermore, during the period of chronic stimulation, the prolongation of twitch contraction time occurred along the same time course for the fast and slow patterns of tonic treatment. All chronically stimulated muscles had become weaker than normal. In comparison to the slow patterns, the present fast patterns of long-term activation caused (1) a smaller amount of decline in maximum muscle force, (2) a smaller twitch: tetanus ratio, and (3) the retention of a normal amount of post-tetanic potentiation of twitch size (decreased by the slow patterns). When tested by a series of 40 Hz bursts, force was better maintained in chronically stimulated muscles than in normal ones. These effects on fatigue resistance were the same for the fast and slow patterns of long-term activation. In peroneus longus muscles contralateral to the side of chronic activation, an evident impairment had commonly occurred in the capability to maintain force during tetani at the high rates needed for a maximum tetanic contraction. The results are discussed in relation to problems concerning the long-term effects of motoneuronal activity patterns on the contractile properties of their muscle units.

Animals↗
PubMed2005

Boron neutron capture enhancement of fast neutron radiotherapy utilizing a moderated fast neutron beam.

An investigation of the therapeutic potential of boron neutron capture (BNC) enhancement of fast neutron therapy utilizing the Harper University Hospital superconducting cyclotron-produced d(48.5)+Be fast neutron therapy beam is presented. A technique for modification of the fast neutron beam to increase the BNC enhancement is presented along with an evaluation of the effects of beam moderation on the biological effectiveness of the absorbed dose. Characteristics of the photon, neutron, and boron neutron capture components of the absorbed dose are presented. Results demonstrate the possibility of therapeutic gains greater than 50% over conventional fast neutron therapy at depths required to treat brain lesions. This enhancement is estimated assuming currently achievable boron concentrations, and is more than adequate to provide a therapeutic window for the effective treatment of Glioblastoma Multiforme without prohibitive toxicity to the normal brain.

Body Burden↗
PubMed2003

[Evaluation of the increase in signal intensity from applying the fast recovery technique to fast spin echo images].

The aim of the present study was to evaluate the increase in signal intensity caused by applying the fast recovery (FR) technique to fast spin echo (FSE) images, that is, the fast recovery fast spin echo (FR-FSE) method. All images of phantoms, whose T(2) values were different, were acquired with a Signa 1.5 Tesla system (GE Medical Systems) using the three-dimensional (3D) FSE and 3D FR-FSE sequences. We assessed the increased signal intensity as follows: (signal intensity on the FR-FSE image - FSE image) / FSE image (%). Our results showed that the increased signal intensity became high when 1) T(2) of the phantom was prolonged, 2) TR was shortened, and 3) echo train length (ETL) was decreased. By utilizing the results of this study, the increased signal caused by the FR technique could be estimated quantitatively when the TR, ETL, and T(2) of investigated substances were determined. For example, when TR, ETL, and T(2) were 1500 msec, 16-64, and 1500 msec, respectively, the increase in signal intensity was estimated to be approximately 70%. In addition, when T(2) was less than approximately 250 msec, signal intensity was not significantly increased by the FR pulses, that is, the FR-FSE image was the same as the FSE image. Accordingly, the FR-FSE method was confirmed to enhance the signal in substances with longer T(2), while maintaining the same contrast of the image as that obtained by the conventional FSE method. Our results are useful for evaluating the increased signal intensity caused by employing the FR technique.

Image Enhancement↗
PubMed1995

[Fast and ultra-fast sequences in MRI of the pelvis and retroperitoneum].

Fast and ultrafast sequences are crucial prerequisite for optimum diagnostic impact in magnetic resonance (MR) imaging of the pelvis and retroperitoneum. In MR imaging of the pelvis, heavily T2-weighted fast turbo spin echo (TSE) sequences with acquisition times of 2-4 min have widely replaced time-consuming conventional T2-weighted SE sequences due to substantial time savings and better image quality. Fast and ultrafast gradient recalled echo (GRE) sequences are the basis of dynamic contrast-enhanced studies. In MR imaging of the retroperitoneum, fast and ultrafast sequences currently play the most important role as they allow for breath-hold acquisition of a sufficient number of images free of motion artifacts. The current roles of TSE, tubo gradient spin echo (TGSE), GRE and echoplanar imaging (EPI) sequences in MR imaging of the pelvis and retroperitoneum is discussed.

Artifacts↗
PubMed1990

Bioavailability of a new sustained-release theophylline capsule in fasted and non-fasted healthy subjects: single and multiple dosing studies.

Eighteen healthy, non-smoking, adult volunteers participated in single and multiple dose three-way crossover studies to evaluate a sustained-release, pellet-filled capsule of theophylline, Austyn. The effect of food on the bioavailability of the sustained-release capsule was investigated by administering 300 mg single doses of Austyn, with a high-fat meal and without food and a divided 300 mg dose of the reference product Elixophyllin elixir, given after fasting. Plasma theophylline concentrations were measured by fluorescence polarization immunoassay (FPIA) which had been validated against HPLC. The single dose study data showed that there were no significant differences (n = 18, ANOVA, p greater than 0.05) between the three regimens with respect to AUC0-infinity values (mg h l-1), (mean +/- SD); Elixophyllin fasting = 97.1 +/- 33.7, Austyn with food = 90.9 +/- 31.3, Austyn fasting = 91.2 +/- 33.8. Similarly, multiple dosing with rapid-release Nuelin tablets, Austyn capsules, and sustained-release Theo-Dur tablets demonstrated that there were no significant differences between regimens with respect to AUC0-24h, AUC0-12h, and AUC12-24h values calculated from the steady-state concentrations (5th day, 24 h sampling). However, the percentage fluctuation at steady-state over the total blood sampling period was significantly less for treatment with the sustained-release capsule. Austyn, compared with the sustained-release tablet, Theo-Dur (Austyn = 36.7 +/- 13.7 per cent, Theo-Dur = 53.1 +/- 14.1 per cent). The results of the single and multiple dose studies indicate that Austyn capsules demonstrate complete bioavailability, and good controlled release characteristics not influenced by concomitant intake of a high-fat meal and with no evidence of dose dumping.

Adult↗
PubMed1991

Regulation of glucose uptake in fast and slow skeletal muscles with fasting and refeeding.

1. The decrease in wet weight and noncollagen protein (NCP) was faster and greater in extensor digitorum longus (EDL) during fasting than in soleus (Sol) muscles in rats. 2. During refeeding, recovery was completed faster in Sol than in EDL. 3. Glucose uptake in skeletal muscle increased significantly during fasting on both a per wet weight and NCP basis. 4. This increase was faster and greater in EDL than Sol. 5. The initial increase in glucose uptake was greater during refeeding than fasting only in EDL.

Animals↗
PubMed2004

IGT with fasting hyperglycemia is more strongly associated with microalbuminuria than IGT without fasting hyperglycemia.

Previous studies have established that impaired glucose tolerance (IGT) patients with fasting hyperglycemia (IGT/FH: fasting plasma glucose (FPG) level 6.1-7.0 mmol/l and 2 h PG level of 7.8-11.1 mmol/l) exhibit higher insulin resistance than those with isolated IGT (FPG level <6.1 mmol/l and 2 h PG level of 7.8-11.1 mmol/l), but the association with microalbuminuria has not been determined. Here, we evaluate the prevalence of microalbuminuria in non-diabetic Japanese males 20-70 years of age. The subjects were classified into four groups based on the results of OGTT: normal glucose tolerance (NGT: n=71), impaired fasting glucose (IFG: n=24), isolated IGT (n=36), and IGT/FH (n=23). A urinary albumin-to-creatinine ratio (ACR) from 30 to 300 microg/mg creatinine was counted as microalbuminuria. The prevalence of microalbuminuria was higher in subjects with IGT/FH than in subjects with isolated IGT (26% versus 14%). Logistic regression analysis showed microalbuminuria to be more significantly associated with IGT/FH (OR=3.82, 95% CI 1.09-13.36) than with isolated IGT (OR=1.75, 95% CI 0.50-6.17). While insulin resistance (HOMA-IR) in isolated IGT was not significantly different from that in NGT, insulin resistance in IGT/FH was significantly higher (P<0.01). Regression analysis of ACR in IGT showed a significant correlation with insulin resistance (P=0.012). Accordingly, microalbuminuria is more strongly associated with IGT/FH than with isolated IGT, most likely due to the higher insulin resistance.

Adult↗
PubMed1999

When is fasting really fasting? The influence of time of day, interval after a meal, and maternal body mass on maternal glycemia in gestational diabetes.

OBJECTIVE: The object of the study was to determine whether time of day, interval after a standard meal, and maternal body mass influence plasma glucose concentrations in women with gestational diabetes mellitus. STUDY DESIGN: Identical mixed meals were administered on 2 separate occasions 1 week apart to 30 women with dietarily treated gestational diabetes and pregnancies between 28 and 38 weeks' gestation. One meal was administered at 7 AM (morning meal) and the other was administered at 9 PM (evening meal), each after a fast of >/=5 hours. The order of the meals (morning first versus evening first) was assigned randomly. Sixteen of the women had a body mass index >/=27 kg/m(2) (overweight) and 14 women had a body mass index <27 kg/m(2) (lean). Venous plasma concentrations of glucose, insulin, free fatty acids, beta-hydroxybutyrate, and bound and free cortisol were measured hourly for 9 hours after each of the test meals. RESULTS: When all women were considered together glucose concentrations after the morning meal were significantly greater at 1 hour, were not different at 2 hours, and were significantly lower from 3 through 9 hours postprandially than those at corresponding times after the evening meal. Plasma beta-hydroxybutyrate and free fatty acid concentrations were higher between 5 and 9 hours after the morning meal than at the same times after the evening meal. Total and free cortisol levels were higher for the first 7 hours after the morning feeding, reflecting known diurnal variation in cortisol concentrations. Overweight patients' glucose values were significantly greater than those of lean subjects during the last 4 hours of the overnight fast. CONCLUSIONS: Among women with dietarily treated gestational diabetes the glucose concentrations were significantly higher from 3 to 9 hours after an evening meal, whereas suppression of free fatty acids and beta-hydroxybutyrate was less sustained after a morning feeding. The mechanisms underlying these differences remain to be determined but may involve diurnal influences of counterregulatory hormones. The relationships between measurements of maternal glycemia and maternal and perinatal outcomes in pregnancies complicated by gestational diabetes may be clarified by establishing a uniform duration of a fast and by developing meal-specific preprandial and postprandial maternal glucose targets for these patients.

3-Hydroxybutyric Acid↗
PubMed1988

Absorption of erythromycin acistrate and erythromycin base in the fasting and non-fasting state.

Absorption of erythromycin acistrate (EA) and two erythromycin base (EB) preparations (enterotablet A and B) taken after an overnight fast or immediately before a standard breakfast was studied in 29 healthy volunteers in three separate studies, in a cross-over, randomized design. In Study I, the absorption of a single dose (400 mg) of EA was similar in the fasting and non-fasting state. There was, however, more interindividual variation and in two subjects absorption was markedly impaired in the presence of food. Cimetidine given at two doses (400 + 800 mg) had no effect on the pharmacokinetics of erythromycin acistrate. In Study II, the effect of food on the bioavailability of the two EB preparations was studied after a single dose of 500 mg (2 x 250 mg enterocoated tablets) and after multiple dosing (2 x 250 mg tid). When given with a standard breakfast, erythromycin base was significantly better absorbed from enterotablet A than from enterotablet B, whether given as a single dose or in repeated doses. Study III followed the same design as Study II except that the tablet size of both enterotablets A and B was now 500 mg. Even in this study the absorption of enterotablet A was significantly better than that of enterotablet B. EA is adequately absorbed when taken before a meal. Cimetidine does not interfere with its elimination. Concomitant food intake produced considerably dissimilar absorption of two commercially available enterocoated EB preparations. Although at steady-state this was less prominent than after a single dose, it may have some clinical significance.

Adult↗
PubMed1982

Fasting and diurnal plasma PP, and the effect of fasting and somatostatin on postprandial plasma PP.

6 healthy subjects were studied on 3 separate occasions after ingestion of an ordinary breakfast. Once the meal was given alone, once together with somatostatin infused i.v. (100 micrograms/h) for the first 2 h after start of the meal, and once the meal was preceded by a 34-h fasting period. The postprandial plasma PP secretion was completely inhibited during the somatostatin infusion, and significantly augmented (p = 0.032) after the prolonged fast. During the 34-h fasting period, the PP levels were almost unaffected. The same group of subjects were also studied during a "normal" day with 4 regular meals. Plasma PP was found to increase shortly after breakfast and did not return to basal levels before early the next morning. The integrated PP secretion during the 24-h period showed a significant (p less than 0.003) correlation with the basal levels.

Adult↗
PubMed1994

Role of hepatic glucose production and glucose uptake in the pathogenesis of fasting hyperglycemia in type 2 diabetes: normalization of glucose kinetics by short-term fasting.

The relative impact of hepatic glucose production (HGP) and peripheral glucose uptake (GU) on plasma glucose concentration was assessed in 54 noninsulin-dependent diabetes mellitus (NIDDM) and 50 control subjects submitted to a variable period of fasting (14-108 h) with special focus on the normal and low hyperglycemic range. Within each population we found a highly significant (P < 0.001) positive correlation between plasma glucose concentration and HGP in the whole range of glycemia, but the slope of the regression line was steeper (P < 0.001) in the diabetic than in the control group. The two curves intersected at a glucose level of 4.0 mmol/L. Therefore, for a given HGP rate above the intersection point, diabetic patients had a higher plasma glucose concentration than nondiabetic individuals, owing to an approximately 15% reduction (P < 0.025) in the metabolic clearance rate, despite the fact that the plasma insulin level was 2-fold higher (P < 0.05) in the diabetic patients. When diabetic and nondiabetic subjects were compared at a similar low glucose level of 4.0 mmol/L brought about by short-term fasting, all parameters of glucose kinetics were identical in both groups. We thus conclude that 1) HGP is the major determinant of plasma glucose concentration in control as well as in diabetic subjects whatever the nutritional state; 2) the slight hyperglycemia prevailing in mild NIDDM results from the combination of an impaired insulin-induced inhibition of HGP and stimulation of GU because both parameters are inappropriately normal in the face of elevated plasma glucose and insulin levels; and 3) the normalization of GU and HGP after short-term fasting suggests that pathways of noninsulin-mediated GU operate in a normal way in NIDDM.

Adult↗
PubMed2004

Inhibition of ryanodine receptor 1 in fast skeletal muscle fibers induces a fast-to-slow muscle fiber type transition.

Skeletal muscle fiber type is regulated by innervation-induced cell signaling including calcium release mechanisms that lead to transcriptional activation of fiber type-specific genes. Avian fast pectoralis major (PM) and slow medial adductor (MA) muscles differentially control expression of the slow myosin heavy chain 2 (slow MyHC2) gene. We report here that slow MyHC2 gene expression in fast PM muscle fibers is repressed by endogenous activity of the ryanodine receptor 1 (RyR1). Inhibition of RyR1 with ryanodine led to expression of the slow MyHC2 gene in innervated PM muscle fibers in vitro. Administration of ryanodine to innervated PM muscle fibers also decreased protein kinase C (PKC) activity, the reduction of which is necessary for slow MyHC2 gene expression in both PM and MA muscle fibers. Furthermore, RyR1 inhibition increased slow MyHC2 promoter activity in innervated PM muscle fibers and enhanced transcriptional activities of nuclear factor of activated T cells (NFAT) and myocyte enhancer factor 2 (MEF2), as well as their interactions with their respective binding sites of the slow MyHC2 promoter. These results indicate that RyR1 activity in innervated fast PM muscle fibers contributes to the cell type-specific repression of slow muscle specific genes.

Animals↗
PubMed1990

Plasma pharmacokinetics of Idarubicin and its 13-hydroxymetabolite after intravenous and oral administration under fasting and non-fasting conditions.

The plasma pharmacokinetics of Idarubicin and its 13-hydroxy-metabolite have been studied in 10 patients with solid tumours after intravenous and oral administration under fasting and non-fasting conditions in a randomized cross-over design. The plasma concentration time curves of Idarubicin after intravenous administration could be described by the open two or three compartment models. No pharmacokinetic modelling of Idarubicin was possible after oral administration. After oral administration of Idarubicin, the amount of intact drug was higher under non-fasting conditions. The extensive and long-lasting appearance of Idarubicinol suggests that this cytotoxic metabolite is of major clinical importance in i.v. and oral therapy with Idarubicin. The pharmacokinetics of Idarubicinol was not affected by food intake.

Administration, Oral↗
PubMed1984

[Modified fasting in the therapy of obesity. A comparison of total fasting and low-calorie diets of various protein contents].

Modified fasting represents a successful therapy for obesity without severe side effects. The daily energy-substitution (1000-1700 kJ) consists of 30-50 g high quality protein, 20-40 g carbohydrates and small amounts of fat. The mean weight loss is 11-14 kg in a four-week treatment period. In contrast to total fasting the weight loss achieved with modified fasting consisted in a percentage of 79% adipose tissue and a minimal protein loss of 3%. The nitrogen equilibrium was reached after one to three weeks thus avoiding the risks of greater protein losses.

Diet, Reducing↗
PubMed1994

[The bioavailability of enteric coated diclofenac formulations. 2. Bioavailability following single administration of a multiple-unit formulation in comparison to a single-unit formulation under fasting and non-fasting conditions].

Relative bioavailability of enteric-coated diclofenac (CAS 15307-86-5) was investigated after a single-dose administration of a multiple-unit formulation (Diclo-Puren 50, test) in comparison to a single-unit formulation (reference). The study was carried out in a four-way change-over design including a group of 12 healthy male volunteers. Each formulation was administered after 10 h of fasting or just after (5 min) finishing a meal (standard breakfast). Diclofenac plasma concentrations were measured using a selective and sensitive GLC-MS method after liquid-liquid extraction and derivatisation. Area under the curve (AUC), maximum plasma concentrations (Cmax), time of maximum plasma concentration (tmax), time of delay of first measurable concentrations (tlag) and plateau time of concentrations above minimum effective concentrations (MEC) of 50 ng/ml (tMEC(50)) and 100 ng/ml (tMEC(100)), respectively, were evaluated as pharmacokinetic characteristics. Additionally, for AUC and Cmax, 90%-confidence intervals (parametric: ANOVA, ANOVAlog, non-parametric: Mann-Whitney) were calculated to evaluate the influence of food on bioavailability of each formulation. Mean (median) relative bioavailabilities of diclofenac of the test formulation (comparison: postprandial vs. fasting conditions) were determined for the test formulation as 96% (103%) and for the reference product as 70% (83%). Mean +/- SD (median) maximum plasma concentrations of the test formulation were determined as 695 +/- 313 (677) ng/ml (fasting) and as 452 +/- 163 (456) ng/ml (postprandial). Maximum plasma concentration occurred 1.2 +/- 0.5 (1.0) h and 4.8 +/- 1.0 (5.0) h after administration, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

A prospective comparison of brain contrast characteristics and lesion detection using single-shot fast spin-echo and fast spin-echo.

MRI is limited by movement artefact, even with current imagers, when examining a restless or claustrophobic patient. We prospectively analysed the images of 92 patients produced by a single-shot fast spin-echo (SSFSE) pulse sequence and compared them with conventional (FSE) and reduced-time fast spin-echo (RT-FSE) techniques, with regard to lesion detection and movement artefact in brain imaging. Images obtained in each case were independently reviewed and scored for overall diagnosis, number of lesions detected, and movement artefact. FSE showed 1217 lesions, RT-FSE 1137, and SSFSE 1044. This discrepancy arose mainly in patients with multiple sclerosis or small-vessel disease, since with SSFSE we were less able to separate small, adjacent low-contrast lesions than with FSE. Arbitrary movement scores were 36, 25 and zero respectively. There were, however, no clinically significant differences in overall diagnosis between the three techniques. SSFSE thus proved a reliable, fast, accurate method for obtaining T2-weighted images, and may be of particular use in the restless, claustrophobic or obtunded patient.

Algorithms↗
PubMed2002

Three-dimensional fast recovery fast spin-echo imaging of the inner ear and the vestibulocochlear nerve.

The aim of this study was to assess the performance of three-dimensional fast recovery fast spin-echo (3DFRFSE) for imaging of the inner ear as well as the facial and vestibulocochlear nerves. We evaluated 3DFRFSE sequences, comparing it with 3D fast spin-echo (3DFSE) in a water phantom and in 12 normal volunteers. We also examined 66 patients using 3DFRFSE sequence and assessed the visualization of their pathologies. In a water phantom study, signal intensity (SI) on 3DFRFSE was higher than that on 3DFSE at the same TR ranging from 1,500 to 6,000 ms. In normal volunteers, 3DFRFSE with TR of 2,800 ms showed comparable SI, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) superior to those on 3DFSE with TR of 5,000 ms. In clinical setting, 3DFRFSE was useful in demonstrating anatomic details in the labyrinth and pathologic findings of inner ear. The 3DFRFSE can provide high-resolution heavily T2-weighted images (T2WI) with shorter scan time than 3DFSE without significant disadvantage. The 3DFRFSE is a beneficial technique for evaluation of lesions in the inner ear as well as the facial and vestibulocochlear nerves.

Ear, Inner↗
PubMed1998

MRI of the uterus, uterine cervix, and vagina: diagnostic performance of dynamic contrast-enhanced fast multiplanar gradient-echo imaging in comparison with fast spin-echo T2-weighted pulse imaging.

The aim of this study was to compare the diagnostic performance of contrast-enhanced fast multiplanar gradient-echo (GRE) and T2-weighted fast spin-echo (FSE) image sets in the assessment of uterus, cervix, and vagina. Fast (up to 20 contiguous sections in 23 s) multiplanar GRE and FSE images of 45 patients referred for imaging of the female pelvis were evaluated retrospectively with regard to overall image quality and the ability to detect normal anatomic structures, as well as lesion conspicuity. Results were compared with histologic findings (n = 29) or clinical follow-up. Furthermore, a quantitative assessment of contrast-to-noise ratios among normal uterine and cervical structures as well as uterine lesions was performed for both sequences. On GRE images, uterine and cervical differentiation was best seen on the image sets acquired 15 and 60 s following contrast enhancement and results were significantly better compared with delayed images (p < 0.05). Delineation of the junctional zone was significantly (p < 0.05) better on FSE compared with GRE images; no significant difference was seen for the other anatomic structures. Overall image quality of GRE and FSE images was similar. Sensitivity for lesion detection based on both GRE and FSE images was 96% with a sensitivity of 93% for GRE, and 81% for FSE images alone, respectively. Using the extended McNemar chi 2 test, the difference in diagnostic performance between FSE and GRE revealed no significant difference, whereas the combination of both techniques performed better than FSE imaging alone (p < 0.05). The presented data suggest that dynamic contrast-enhanced GRE imaging should be part of an MR examination of the female pelvis. Combined GRE and FSE imaging provide an excellent sensitivity in the assessment of uterine and vaginal pathologies.

Adolescent↗