Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FASTING”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60Linked to original sources
PubMed1985

Isoproterenol inhibits residual fast channel via stimulation of beta-adrenoceptors in guinea-pig ventricular muscle.

When perfused with high K+ (8.1 to 14.9 mM)-Tyrode's solution, the upstroke of action potentials in the isolated guinea-pig ventricular muscle is composed of two components and there are two separable peaks in the first derivative, i.e., Vmax, fast and Vmax, slow. The Vmax, fast was a measure of activation of the residual fast channel, while the Vmax, slow was that of the slow channel. Isoproterenol depressed Vmax, fast with increase in Vmax, slow, in a concentration-dependent manner (10(-8) to 10(-6) M). This depression of Vmax, fast was greater at more depolarized levels of membrane potential. Therefore, the isoproterenol-induced depression of Vmax, fast may be due to a negative shift of the curve relating Vmax, fast to the take-off potential (Em) (Vmax--Em relationship), along the voltage axis. The negative shift of Vmax--Em relationship by isoproterenol was also recognized in small preparations the size of which is well within the space constant. The negative shift was inhibited in the presence of beta-blockers (pindolol 1 microgram/ml or atenolol 10 micrograms/ml) but not by a calcium antagonist, 1-verapamil (1 microgram/ml). These results suggest that isoproterenol blocks sodium channels in the depolarized ventricular muscle via stimulation of the beta-adrenoceptors and that the depression of Vmax, fast is not mediated by the well-known effects of isoproterenol on Vmax, slow, i.e., increased influx of Ca2+ ions.

Action Potentials↗
PubMed1999

Randomized trial of "slow" versus "fast" feed advancements on the incidence of necrotizing enterocolitis in very low birth weight infants.

OBJECTIVE: To determine whether the rate of feed advancement affects the incidence of necrotizing enterocolitis (NEC). STUDY DESIGN: Prospective randomized controlled trial involving 185 formula-fed infants with birth weight 501 to 1500 g and gestational age </=34 weeks. Infants were randomized into 2 groups: "slow" (n = 98), who received 15 cc/kg/d increments (a 10-day schedule to full feeds) and "fast" (n = 87), who received 35 cc/kg/d increments (a 5-day schedule to full feeds) of Similac Special Care 20 cal/oz. Feeds were increased only if well tolerated as defined by a protocol. RESULTS: The incidence of NEC (Bell stage >/=II) was similar in both groups (slow 13% and fast 9%, P =.5). The incidence of perforation (Bell stage III) was also similar in both groups (slow 4% and fast 2%, P =.8). Feeds were started at a comparable postnatal age in both groups (median age: slow 5 days and fast 4 days, P =.9). Although the neonates in the fast group attained full enteral intake earlier (median days [25th and 75th percentiles]: slow 15 [12, 21] and fast 11 [8, 15], P <.001) and regained their birth weight earlier (slow 15 [11, 20] and fast 12 [8, 15], P <.05), their ages at discharge were not statistically different (slow 47 [31, 67] and fast 43 [29, 62], P =.3) CONCLUSIONS: A greater than twofold difference in the rate of feed advancement from 15 cc/kg/d to 35 cc/kg/d did not affect the incidence of NEC >/= stage II. Factors other than feed advancement appear to be more important in the pathogenesis or progression of NEC.

Age Distribution↗
PubMed1998

Correlation between fasting glucose in the first trimester and glucose challenge test in the second.

OBJECTIVE: To determine if there is a statistically significant correlation between the plasma glucose level obtained following a glucose challenge test at 24-28 weeks' gestation and the fasting plasma glucose level in the first trimester. METHODS: The study population included 621 healthy women with singleton pregnancies followed in the antenatal clinic of the Hadassah Medical Center, with a fasting plasma glucose level performed during the first trimester. Nine women had fasting blood glucose levels above 105 mg/dL and were excluded from the study. Of the remaining 612 women, 425 (69%) had 50-g glucose challenge tests at 24-28 weeks' gestation. RESULTS: The mean (+/-standard deviation [SD]) first-trimester fasting glucose level was 77.8+/-9.7 mg/dL and the mean (+/-SD) glucose level 1 hour after the second-trimester glucose challenge test was 109.1+/-29.8 mg/dL. The fasting plasma glucose level and the glucose level following the glucose challenge correlated significantly but not strongly (=.26, P < .001). However, using a linear regression model in which fasting plasma glucose level and maternal weight were explanatory variables and glucose level following the glucose challenge test was the dependent variable resulted in a very low r2 (.10). CONCLUSION: The correlation between the plasma glucose level obtained following a glucose challenge test and the fasting plasma glucose level in the first trimester is low, indicating that fasting glucose measurement early in pregnancy has no clinical benefits.

Adolescent↗
PubMed1999

Odor-induced fast waves in the dentate gyrus depend on a pathway through posterior cerebral cortex: effects of limbic lesions and trimethyltin.

Previous research has shown that the odor of a variety of organic solvents and of components of the anal scent gland excretions of various predators will elicit a burst of fast waves of about 20 Hz in the olfactory bulb, pyriform cortex, and dentate gyrus of the rat. The present experiments show that large lesions of the caudal cerebral cortex, involving particularly the entorhinal and subicular cortices and the angular bundle, abolish the olfactory fast wave response of the dentate gyrus, but not the similar response of the olfactory bulb. In confirmation of previous work, such a lesion also abolishes an average evoked response elicited in the dentate gyrus by electrical stimulation of the olfactory bulb. Systemic treatment with the neurotoxin trimethyltin abolished the olfactory fast wave response in the olfactory bulb and both the olfactory fast wave and the olfactory evoked potential in the dentate gyrus. Large lesions of the amygdala or the septal nuclei did not eliminate either the dentate olfactory evoked potential or the odor-induced dentate fast wave response. However, the septal lesion reduced the amplitude of both spontaneous and odor-induced dentate fast wave activity. It is suggested that olfactory stimuli elicit 20 Hz dentate fast waves via a pathway from the olfactory bulb through the entorhinal cortex and, further, that cholinergic interneurons in the dentate gyrus may be essential to the dentate fast wave response.

Amygdala↗
PubMed1999

Volume fast spin-echo imaging of the cervical spine.

RATIONALE AND OBJECTIVES: The authors prospectively evaluated a T2-weighted, three-dimensional (3D) volume, fast spin-echo (SE) pulse sequence in assessment of the cervical spine and compared it with standard imaging protocol. MATERIALS AND METHODS: Eighteen patients with neck pain underwent magnetic resonance (MR) imaging at 1.5 T with two-dimensional (2D) fast SE and axial 3D gradient-echo (GRE) protocols and with an additional sagittal T2-weighted volume fast SE protocol. The spinal cord and canal, neural foramina, and intervertebral disks were assessed by two neuroradiologists, and the results were compared with reports from the standard protocol. The quality of the partition (direct sagittal) and reconstructed images were evaluated. RESULTS: No differences existed in the assessment of spinal cord disease or disk herniation with 2D fast SE and volume fast SE imaging. Some mild variation occurred in assessment of the neural foramina. Partition images demonstrated a high level of resolution and contrast, while reconstructed images had consistently lower quality. However, this did not impede detection and grading of disk or spinal abnormalities, which were adequately shown on volume fast SE sagittal images. Neural foramina were well demonstrated on axial reconstructions from volume fast SE imaging. CONCLUSION: Volume fast SE imaging provides information about the spinal cord, canal, disks, and neural foramina that is comparable to the information provided by routine imaging. Its thinner sections and multiplanar reconstruction capability are advantages over 2D imaging. Its greater tissue contrast with better visualization of the cervical cord, greater signal-to-noise ratio, and less susceptibility artifact are advantages over 3D GRE imaging.

Adult↗
PubMed1994

Ethanol enhances agonist-induced fast desensitization in nicotinic acetylcholine receptors.

The reversible decline of the nicotinic acetylcholine receptor's response to acetylcholine during prolonged exposure to acetylcholine is known as desensitization. Here, we studied ethanol's modulation of fast agonist-induced desensitization of the nicotinic acetylcholine receptor in postsynaptic membrane vesicles from Torpedo using a fast kinetic technique: pulsed quenched flow. Preincubation of the vesicles with various concentrations of acetylcholine at 4 degrees C for times ranging from 80 ms to 1.5 s caused fast desensitization, which was revealed as a decreased 86Rb+ influx when the vesicles were subsequently briefly exposed to a saturating concentration of acetylcholine in 86RbCl. Acetylcholine-induced fast desensitization had a maximum observed rate, kdmax, of 6.8 s-1, a half-effect concentration, KD, of 157 microM, and a Hill coefficient of 1.4. Increasing the ethanol concentration up to 1.0 M causes a linear increase in kdmax, such that 1.0 M ethanol doubles the rate. Ethanol (1 M) also decreased KD 10-fold without changing the Hill coefficient. We consider a modified sequential model to interpret our data. Two acetylcholine molecules bind sequentially to the receptor's resting state to form a pre-open (closed) state, which then opens and, at very high acetylcholine concentrations, is inhibited. A priori fast desensitization might occur from any of these acetylcholine-occupied states. If we assume fast desensitization to occur solely from the pre-open state, our data predict an excessively large action of ethanol on the fast desensitization rate constant (> 200-fold increase in the desensitization rate constant at 1 M ethanol). When we assume fast desensitization to occur from all states, ethanol is seen to have two actions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1998

SITA Fast, a new rapid perimetric threshold test. Description of methods and evaluation in patients with manifest and suspect glaucoma.

PURPOSE: To describe and evaluate the new rapid SITA Fast computerized perimetric threshold strategy. METHOD: Computer simulations of visual fields were used to develop a new rapid threshold strategy, SITA Fast. In a clinical evaluation 30 patients were examined twice with each of the Full Threshold, Fastpac and SITA Fast strategies. RESULTS: SITA Fast had significantly shorter test time using on average 34% of the test time when compared to the Full Threshold strategy (p<0.0001) and 53% compared to Fastpac (p<0.0001). Reproducibility, calculated as the average Root Mean Square Error, was 1.84 dB in SITA tests, and 1.99 dB and 2.02 dB with Full Threshold and Fastpac, respectively. Both SITA Fast and Fastpac showed slightly higher sensitivities on average than theoretically expected. Sensitivity differences were larger in eyes with large differences in test time. Defects detected by SITA Fast were often deep and more localised than those detected by the Full Threshold and the Fastpac strategies. CONCLUSION: SITA Fast tests were considerably shorter than Fastpac tests. The low test-retest variability found in the SITA Fast tests implies that it may be a sensitive test for detection of field progression.

Aged↗
PubMed2006

The association of television and video viewing with fast food intake by preschool-age children.

OBJECTIVE: To examine the extent to which television (TV) and video viewing is associated with consumption of fast food by preschool-age children. RESEARCH METHODS AND PROCEDURES: In a cross-sectional study of 240 parents of children ages 2.0 to 5.9 years, parents reported the number of hours their child watched TV/videos on an average weekday and weekend day in the past month; a daily, weighted average of TV/video viewing was then calculated. The main outcome was parents' report of their children's fast food intake, using the question, "How many times a week does your child eat at fast food restaurants such as McDonald's, Burger King, or Kentucky Fried Chicken?" dichotomized to (never/<1 vs. > or =1 time/wk). The association of TV/video viewing with fast food intake was evaluated by multiple logistic regression before and after adjusting for several potential confounders. RESULTS: Twenty-two percent of parents reported that their child ate at fast food restaurants at least once per week. After adjusting for parents' age, race/ethnicity, and household income as well as child's age and sex, for each 1-hour increase of TV/video watched per day, the odds ratio (OR) for consuming fast food > or =1 time per week was 1.60 (95% confidence interval, 1.03 to 2.49). After further adjustment for socio-environmental factors that might serve as proxies for the availability of healthy food options, such as parental time constraints and the availability and high cost of fresh fruits and vegetables in their neighborhoods, the OR for consuming fast food > or =1 time per week was minimally attenuated (OR, 1.55; 95% confidence interval, 1.04 to 2.31). DISCUSSION: TV/video viewing was correlated with fast food consumption among preschool children in this study. Our findings raise the possibility that greater exposure to TV and videos may influence preschool children's consumption of unhealthful foods.

Body Height↗
PubMed2000

Fast food restaurant use among women in the Pound of Prevention study: dietary, behavioral and demographic correlates.

OBJECTIVE: To examine demographic, behavioral and dietary correlates of frequency of fast food restaurant use in a community-based sample of 891 adult women. DESIGN: A survey was administered at baseline and 3 y later as part of a randomized, prospective intervention trial on weight gain prevention. SUBJECTS: Women (n = 891) aged 20-45 y who enrolled in the Pound of Prevention study. MEASUREMENTS: Frequency of fast food restaurant use, dietary intake, demographic and behavioral measures were self-reported. Dietary intake was measured using the 60-item Block Food Frequency Questionnaire. Body weight and height were directly measured. RESULTS: Twenty-one percent of the sample reported eating > or = 3 fast food meals per week. Frequency of fast food restaurant use was associated with higher total energy intake, higher percentage fat energy, more frequent consumption of hamburgers, French fries and soft drinks, and less frequent consumption of fiber and fruit. Frequency of fast food restaurant use was higher among younger women, those with lower income, non-White ethnicity, greater body weight, lower dietary restraint, fewer low-fat eating behaviors, and greater television viewing. Over 3 y, increases in frequency of fast food restaurant use were associated with increases in body weight, total energy intake, percentage fat intake, intake of hamburgers, French fries and soft drinks, and with decreases in physical activity, dietary restraint and low-fat eating behaviors. Intake of several other foods, including fruits and vegetables, did not differ by frequency of fast food restaurant use. CONCLUSION: Frequency of fast food restaurant use is associated with higher energy and fat intake and greater body weight, and could be an important risk factor for excess weight gain in the population.

Adult↗
PubMed1998

Serum total sialic acid, a reputed cardiovascular risk factor, and its relationship to lipids, plasma fasting insulin, blood pressure and body mass index in normal individuals.

1. Serum sialic acid is a reputed cardiovascular risk factor, but the reason why this is so is not clear. We therefore studied its relationship with other known cardiovascular risk factors (particularly those associated with insulin resistance) in 100 healthy young subjects (54 females and 46 males, age 20.7+/-0.89 years). 2. There was a significant univariate correlation between serum total sialic acid and fasting plasma insulin. Serum total sialic acid also correlated with fasting plasma glucose concentration and serum cholesterol and triacylglycerol. 3. In females there was a strong univariate correlation between serum total sialic acid and plasma fasting insulin and glucose concentrations, although in males there was a weaker univariate correlation between serum total sialic acid and fasting plasma glucose and the insulin resistance index. In addition, serum total sialic acid significantly correlated with systolic blood pressure, fasting serum cholesterol and triacylglycerol concentrations and body mass index in the females. In males serum total sialic acid significantly positively correlated with fasting serum cholesterol and triacylglycerol concentrations, and correlated inversely with the hip/waist ratio. 4. In multiple regression analysis of the 100 subjects serum total sialic acid correlated independently with fasting serum cholesterol, glucose and also plasma insulin concentrations. In females serum total sialic acid independently correlated with systolic and diastolic blood pressure, and serum cholesterol and fasting plasma glucose concentrations, although there was no significant independent correlation between serum total sialic acid and any of the other variables in the males.

Adult↗
PubMed1994

Role of innervation for development and maintenance of troponin subunit isoform patterns in fast- and slow-twitch muscles of the rabbit.

This study investigates the neural influence on the establishment and maintenance of muscle type-specific expression patterns of the three troponin (Tn) subunits, troponin T (TnT), troponin C (TnC), and troponin I (TnI) during postnatal development and in the adult rabbit. For this purpose, we followed changes in the expression of fast and slow TnT, TnC, and TnI isoforms at the protein and mRNA level in slow- and fast-twitch muscles. During postnatal development all fast Tn isoforms increased in fast-twitch muscle. Sequential transitions (TnTs-->TnT3f-->TnT1f) occurred in the TnT isoform pattern. These changes occurred in parallel with sequential transitions in the pattern of myosin heavy chain (HC) isoforms. Neonatal slow-twitch muscle displayed more mature (slow) isoform patterns for both TnT subunits and myosin HCs than fast-twitch muscle. Although the expression of slow TnC in slow-twitch muscle required innervation, denervation had little effect on slow TnT and TnI which seemed to be controlled by an intrinsic program. In fast-twitch muscle, denervation enhanced the expression of all slow Tn subunit isoforms. In addition, it led to a pronounced increase of the slow TnT2s isoform such that the amount of TnT2s exceeded that of TnT1s. The effects of denervation together with previous data on low-frequency stimulated muscle indicate that the expression of fast Tn isoforms in fast-twitch muscle is neurally controlled. The pattern of slow Tn isoforms in slow-twitch muscle seems to be regulated by an intrinsic program and, in addition, by neural influences.

Animals↗
PubMed2000

Fast oscillations display sharper orientation tuning than slower components of the same recordings in striate cortex of the awake monkey.

We wanted to know whether fast oscillations ( approximately 30-80 Hz) in striate cortex of awake monkeys show sharper orientation selectivity than (i) slower components, including spike rate modulations, and (ii) broad-band signals of the same recordings. As fast oscillations are probably of cortical origin this may further clarify whether cortical network mechanisms are substantially involved in generating orientation selectivity. We recorded multi unit activity (MUA) and local field potentials (LFP, 1-140 Hz) by the same microelectrodes from upper layers of macaque striate cortex during visual stimulation with grating textures of different orientations. An orientation index (OI) was derived from the cortical responses in three frequency ranges (low, 0-11.7 Hz; medium, 11.7-31.3 Hz; and fast oscillations, 31.3-62.5 Hz) and for the broad-band LFP and MUA power. (i) Both LFP and MUA fast oscillations reveal a higher orientation index than signal components in the low and medium frequency ranges. (ii) For MUA the orientation index was significantly higher with fast oscillations than for the lower frequency ranges and the initial broad-band transient responses. (iii) LFPs show a significantly higher orientation index only for the fast oscillations during sustained activation compared with their broad-band power during the transient responses. Thus, our main result is the sharper orientation tuning of fast oscillations in spike activities of local populations compared with slower components of the same broad-band recordings. As fast oscillations occur synchronized in the awake monkey's striate cortex we assume that they have enhanced probability of activating successive stages of visual processing and hence contribute to the perception of orientation.

Animals↗
PubMed2000

Impaired glucose tolerance and fasting hyperglycaemia have different characteristics.

AIMS: Use of the oral glucose tolerance test (OGTT) to define glucose intolerance in the general population may bias towards selection of those with insulin resistance. Beta cell function and insulin resistance markers were analysed in four groups: controls (n = 101); fasting hyperglycaemia (FH, n 45); impaired glucose tolerance; (IGT, n = 16) and those with features of both FH and IGT ('Both', n = 30). METHODS: Subjects underwent an OGTT. Plasma glucose, fasting lipid profiles, fasting, 30 and 120 min insulin were measured and beta cell function (% B) and insulin sensitivity (% S) assessed by homeostatic model assessment (HOMA) RESULTS: The FH group compared to controls had a significantly lower % B. The IGT group compared to controls had features of insulin resistance (higher body mass index (BMI), systolic blood pressure and 2 h insulin concentration). Subjects with 'both' IGT and FH had features of insulin resistance (higher BMI, systolic and diastolic blood pressure and triglyceride concentration) as well as beta cell dysfunction with a lower % B and 30 min insulin-glucose ratio compared to controls. There was a preponderance of males in this group. In all, 192 subjects' 30-min insulin concentration and incremental insulin response showed only a significantly negative correlation with fasting glucose concentration. In a linear regression analysis, a low 30-min insulin-glucose ratio was only a significant factor in the fasting glucose model. Thus, higher fasting glucose concentrations appear to be associated with beta cell dysfunction. However, HbA1 only showed a significant correlation with 120-min glucose, not fasting glucose concentration. CONCLUSIONS: In those with milder degrees of glucose intolerance, FH is associated with beta cell dysfunction and those with IGT and a relatively 'normal' fasting glucose have features of the insulin resistance syndrome.

Aged↗
PubMed1973

Both the fast and slow refolding reactions of ribonuclease A yield native enzyme.

The fast reaction ((T2) approximately 50 msec) observed previously in the refolding of thermally unfolded ribonuclease A (disulfide bonds intact) has now been studied by two properties indicative of enzyme function: binding of a competitive inhibitor (2'CMP) and hydrolysis of a substrate (CpA --> C > p + A). Both the binding and catalytic reactions are fast (<2 msec) compared to refolding. Binding of 2'CMP occurs during both fast and slow refolding reactions, and the protein folded in the fast reaction has a normal binding constant for 2'CMP. Recovery of enzymatic activity during the fast refolding reaction, as measured by the rate of CpA hydrolysis, parallels the kinetic curve for 2'CMP binding. When the kinetics of refolding are measured by the burying of exposed tyrosine groups, no difference is found. The presence of 2'CMP has no effect on the kinetics of refolding. The results show that the fast refolding reaction does not yield an intermediate in the refolding of RNase A. Instead, both fast and slow refolding reactions have a common product, fully active RNase A. Although they show a 100-fold difference in rates of refolding, the starting materials for the fast and slow refolding reactions have similar properties, as regards: (a) the molar absorbancy at 286 nm, reflecting the state of exposed tyrosine groups, and (b) their apparent failure to bind 2'CMP.

Binding Sites↗
PubMed1980

Fast axonal transport in auditory neurons of the guinea pig: a rapidly turned-over glycoprotein.

Proteins of the fast component of axonal transport were analyzed by one- and two-dimensional polyacrylamide gel electrophoresis in the guinea pig spiral ganglion, which has its cell bodies in the cochlea and its axons in the eighth cranial nerve projecting to the ipsilateral cochlear nucleus. We found that we could easily identify the proteins of the fast component even though these axons are only about 3 mm long because the cochlea minimized diffusion of labeled precursor into the cochlear nucleus. The composition of the fast component of the spiral ganglion cells was similar, but not identical, to the fast component of guinea pig retinal ganglion cells. One difference was the predominance in the spiral ganglion cell fast component of a rapidly turned-over glycoprotein (RTGP) with a molecular weight of 110,000-140,000 and an isoelectric point of 5.0 RTGP accumulated in the cochlear nucleus for just the first 3 hr after the application of the labeled precursor and then rapidly disappeared, whereas the other major fast component polypeptides continued to accumulate for 12-24 hr. RTGP was also tentatively identified in the fast component of retinal ganglion cells, but was not as prominently labeled relative to the other fast-component proteins in those cells. The rapid disappearance of RTGP from spiral ganglion cell terminals in the cochlear nucleus may be a result of secretion, perhaps as part of a synaptic vesicle, or retrograde transport as a feedback signal. The difference in the relative amounts of RTGP found in spiral ganglion and retinal ganglion cell terminals may reflect differences in the fundamental properties of the two groups of neurons.

Animals↗
PubMed1999

Smad3 inhibits transforming growth factor-beta and activin signaling by competing with Smad4 for FAST-2 binding.

Transcriptional regulation by transforming growth factor-beta and activin is mediated by interaction of Smad2 and Smad3 with specific transcription factors and/or DNA elements. However, Smad3 behaves differently from Smad2 in regulating transcription by a winged-helix transcription factor, FAST-2, on an activin-responsive element (ARE) in the Xenopus Mix.2 promoter. Smad3 alone was able to stimulate the ARE through FAST-2, but inhibited the ARE transactivation mediated by Smad2/Smad4 following receptor activation. We characterized the functional domains that are involved in these two activities of Smad3. Deletion of the MH1 domain as well as mutations of four lysine residues in the MH1 domain abrogated the inhibitory activity of Smad3, but did not compromise the self-stimulatory function. In contrast, deletion of the MH2 domain or a point mutation of glycine 379 within this domain obliterated the self-stimulatory activity of Smad3, but not the inhibitory activity. In an electrophoretic mobility shift assay, we found that Smad3 was able to associate with the FAST-2.ARE complex and that this association was dependent on FAST-2. In addition, Smad3 was not able to directly bind the ARE in a DNase I protection assay, in which FAST-2 binds the ARE around a motif (TGTGTATT) previously characterized to associate with the human FAST-1 protein. Interestingly, Smad4 was also able to directly associate with the FAST-2.ARE complex through binding with FAST-2. In a gel shift assay, the association of FAST-2 with Smad4 was mutually exclusive from the association with Smad3. Taken together, these data indicate that Smad3 exerts the inhibitory activity by competitive association with FAST-2.

Activin Receptors↗
PubMed2004

Generation of Aspergillus- and CMV- specific T-cell responses using autologous fast DC.

BACKGROUND: Recent reports have described a new strategy for differentiation and maturation of monocyte (Mo)-derived DCs within only 48 h of in vitro culture (fast-DC). Here we assess the efficacy of the fast-DC to process and present different Aspergillus fumigatus and CMV Ag preparations to autologous T cells, compared with DCs generated in standard 7-day cultures (standard-DC). METHODS: Adherent blood Mo were treated with GM-CSF and IL-4 (1 day for fast-DC, 5 days in the standard-DC) to generate immature DCs, and then were matured for either 1-2 days (fast-DC) or 2 days (standard-DC) with inflammatory cytokines. DCs were pulsed with A. fumigatus or CMV Ag preparation immediately prior to maturation, or infected after maturation with adeno-pp65. Mature DCs were then used to prime Ag-specific proliferative and cytotoxic T lymphocytes (CTL) responses. RESULTS: Fast-DC were CD14- and expressed mature DC surface markers to the same degree as standard-DC, and maintained this phenotype after withdrawing cytokine from the cultures. Fast-DC and standard-DC were equally capable of inducing A. fumigatus and CMV-specific T-cell proliferation, as well as priming Ag-specific CTL activity. The Aspergillus- and CMV-specific CTL were of mixed CD3+/CD4+ and CD3+/CD8+ phenotype, and specifically killed autologous DC pulsed with A. fumigatus Ag and autologous CMV infected fibroblasts, respectively. DISCUSSION: Fast-DC are as effective as standard-DC in the generation of Ag-specific T-cell responses. Moreover, use of fast-DC not only reduces labor and supply cost, as well as workload and time, but also increases the number of DCs derived from adherent Mo, which may facilitate the use of DCs in clinical trials of cellular immunotherapy.

Antigen Presentation↗
PubMed1999

The position of the fast-inactivation gate during lidocaine block of voltage-gated Na+ channels.

Lidocaine produces voltage- and use-dependent inhibition of voltage-gated Na+ channels through preferential binding to channel conformations that are normally populated at depolarized potentials and by slowing the rate of Na+ channel repriming after depolarizations. It has been proposed that the fast-inactivation mechanism plays a crucial role in these processes. However, the precise role of fast inactivation in lidocaine action has been difficult to probe because gating of drug-bound channels does not involve changes in ionic current. For that reason, we employed a conformational marker for the fast-inactivation gate, the reactivity of a cysteine substituted at phenylalanine 1304 in the rat adult skeletal muscle sodium channel alpha subunit (rSkM1) with [2-(trimethylammonium)ethyl]methanethiosulfonate (MTS-ET), to determine the position of the fast-inactivation gate during lidocaine block. We found that lidocaine does not compete with fast-inactivation. Rather, it favors closure of the fast-inactivation gate in a voltage-dependent manner, causing a hyperpolarizing shift in the voltage dependence of site 1304 accessibility that parallels a shift in the steady state availability curve measured for ionic currents. More significantly, we found that the lidocaine-induced slowing of sodium channel repriming does not result from a slowing of recovery of the fast-inactivation gate, and thus that use-dependent block does not involve an accumulation of fast-inactivated channels. Based on these data, we propose a model in which transitions along the activation pathway, rather than transitions to inactivated states, play a crucial role in the mechanism of lidocaine action.

Anesthetics, Local↗