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At least 451 records · Page 25Linked to original sources
PubMed1984

Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Determination of fiber and fiber constituents in food and stools.

A procedure is described for the determination of total neutral detergent fiber in composite food and stool samples. This procedure also determines hemicellulose, cellulose, lignin, and cutin + silica in these samples. The quantitation of pectins which involves a separate independent procedure is also described. The present modified neutral detergent fiber procedure yielded values that were significantly higher than the crude fiber method described in previous literature.

Dietary Fiber↗
PubMed1998

Warm and cold sensory thresholds in patients with unilateral sciatica: C fibers are more severely affected than A-delta fibers.

OBJECTIVES: In order to evaluate if nerve root compression or inflammation is the most important pathogenetic mechanism in lumbar radicular pain, we investigated unmyelinated C-fiber function (warm sensation) and myelinated A-delta fiber function (cold sensation) in patients with unilateral L5 or S1 sciatica. MATERIAL AND METHODS: Forty consecutive patients with clinical and radiological evidence of unilateral L5 (n = 29) or S1 (n = 11) sciatica were studied. The warm and cold sensory thresholds (Somedic thermotest, method of limits) were measured on the anterolateral leg (L5 dermatome) and on the calf (S1 dermatome) on both sides. RESULTS: Warm thresholds were significantly higher on the symptomatic side compared to the non-symptomatic side (8.4+/-3.0 vs 6.2+/-2.5 degrees C, P < 0.0005) in the affected dermatome. In a subgroup with confirmed disk herniation at surgery (32 of the 34 operated), significant differences between the symptomatic and the non-symptomatic side for the affected dermatome, were found for both warm (P < 0.0005) and cold (P = 0.003) thresholds. No threshold difference was seen in patients with disk herniations contained within the outer annulus fibrosis (n = 22) compared to those with non-contained herniations (n = 10). CONCLUSIONS: Patients with unilateral sciatica and L5 or S1 nerve root involvement had increased warm thresholds suggesting impaired C-fiber function. Cold thresholds were significantly elevated in a subgroup with operatively confirmed disk herniation. Because myelinated axons are affected more by compression than unmyelinated ones, our results suggest that nerve root inflammation is more important than compression per se in the generation of sciatic pain.

Adult↗
PubMed1993

Amounts of viable anaerobes, methanogens, and bacterial fermentation products in feces of rats fed high-fiber or fiber-free diets.

We investigated the impact of dietary fiber on the fecal output of microorganisms and microbial fermentation products of rats. Two groups of five male Wistar rats were fed high-fiber (HF) and fiber-free (FF) diets in the following order: (group 1) lab chow-->HF-->FF-->HF and (group 2) lab chow-->FF-->HF-->FF. Daily fecal output of total viable anaerobes was 71 times higher with the HF diet. Daily output of methanogens was 1.4 times higher for the HF diet than for the FF diet. Daily excretion of total fermentation acid products (acetate, propionate, butyrate, lactate, succinate, and formate) was 2.4 and 0.1 mmol for HF and FF diets, respectively. The ratios of acetate/propionate/butyrate were 69:21:10 for the HF diet and 92:7:1 for the FF diet. The results show that an HF diet significantly increases microbial growth in the colon and influences the proportions of organic acid products. The HF diet did not increase the ratio of methanogens to total anaerobes. We suggest that the contribution of host-derived substrates to colonic microbial growth and fermentation is insignificant.

Animals↗
PubMed1992

Calcium transients evoked by climbing fiber and parallel fiber synaptic inputs in guinea pig cerebellar Purkinje neurons.

1. Calcium transients related to climbing fiber (CF) and parallel fiber (PF) synaptic potentials were recorded from Purkinje cells in guinea pig cerebellar slices. Transients were measured using either absorbance changes of arsenazo III or fluorescence changes of fura-2, which were injected into individual cells in the slice. 2. All-or-none somatically recorded CF potentials elicited by white matter stimulation had all-or-none Ca transients. These signals began with a delay of > or = 2 ms from the start of the electrically recorded synaptic potential. The recovery time of CF-induced arsenazo III absorbance transients was < 50 ms in the fine dendrites in conditions that minimized the effects of dye buffering. 3. Ca2+ entry through voltage-gated Ca channels opened by Ca action potentials was the dominant source of the rise in [Ca2+]i after CF activation. There was no significant change in [Ca2+]i corresponding to the plateau potential that followed the large CF response. 4. The appearance and amplitude of distal CF-evoked Ca signals was more variable than proximal signals, suggesting that CF potentials do not reliably spread to the fine distal dendrites. The distal transient could be enhanced by intrasomatic depolarizing pulses, suggesting that it was a property of the postsynaptic membrane and not the presynaptic side of the CF synapse that was responsible for this variability. 5. Parallel fiber responses were evoked by electrical stimulation near the pial surface. Graded synaptic potentials and related Ca transients were reversibly blocked by 2 microM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Small synaptic potentials induced small, localized Ca transients. With increasing stimulus intensity, the PF electrical response developed a regenerative component. Larger dendritic Ca transients were detected corresponding to this component. Ca transients evoked by the regenerative responses had the same rapid rise times and fall times as those related to somatically stimulated Ca action potentials, suggesting that they also were due to Ca2+ entry through voltage-sensitive channels. 6. During trains of PF responses, we observed an increase in the spatial extent of related Ca transients. This effect could be modulated by changes in the resting potential, suggesting that the same intrinsic mechanism was affecting the spread of both CF and PF signals.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1997

Temporal summation of C-fiber afferent inputs: competition between facilitatory and inhibitory effects on C-fiber reflex in the rat.

Long-lasting facilitations of spinal nociceptive reflexes resulting from temporal summation of nociceptive inputs have been described on many occasions in spinal, nonanesthetized rats. Because noxious inputs also trigger powerful descending inhibitory controls, we investigated this phenomenon in intact, halothane-anesthetized rats and compared our results with those obtained in other preparations. The effects of temporal summation of nociceptive inputs were found to be very much dependent on the type of preparation. Electromyographic responses elicited by single square-wave electrical shocks (2 ms, 0.16 Hz) applied within the territory of the sural nerve were recorded in the rat from the ipsilateral biceps femoris. The excitability of the C-fiber reflex recorded at 1.5 times the threshold (T) was tested after 20 s of electrical conditioning stimuli (2 ms, 1 Hz) within the sural nerve territory. During the conditioning procedure, the C-fiber reflex was facilitated (wind-up) in a stimulus-dependent fashion in intact, anesthetized animals during the application of the first seven conditioning stimuli; thereafter, the magnitude of the responses reached a plateau and then decreased. Such a wind-up phenomenon was seen only when the frequency of stimulation was 0.5 Hz or higher. In spinal, unanesthetized rats, the wind-up phenomenon occurred as a monotonic accelerating function that was obvious during the whole conditioning period. An intermediate picture was observed in the nonanesthetized rat whose brain was transected at the level of the obex, but the effects of conditioning were profoundly attenuated when such a preparation was anesthetized. In intact, anesthetized animals the reflex was inhibited in a stimulus-dependent manner during the postconditioning period. These effects were not dependent on the frequency of the conditioning stimulus. Such inhibitions were blocked completely by transection at the level of the obex, and in nonanesthetized rats were then replaced by a facilitation. A similar long-lasting facilitation was seen in nonanesthetized, spinal rats. It is concluded that, in intact rats, an inhibitory mechanism counteracts the long-lasting increase of excitability of the flexor reflex seen in spinal animals after high-intensity, repetitive stimulation of C-fibers. It is suggested that supraspinally mediated inhibitions also participate in long term changes in spinal cord excitability after noxious stimulation.

Animals↗
PubMedDate not supplied

Famine, fiber, fatty acids, and failed colonic absorption: does fiber fermentation ameliorate diarrhea?

The salvage function of the colon for absorption of unabsorbed sodium and water from the jejunum and ileum depends upon the metabolic integrity of colonic epithelial cells maintained by luminal short-chain fatty acids. With the depletion of luminal short-chain fatty acids under conditions of starvation, metabolic compensation from vascular substrates is incomplete. Loss of luminal short-chain fatty acids diminishes cell membrane integrity and causes secretion by colonic epithelial cells, leading to starvation diarrhea. Because sodium absorption is dependent upon CO2 production from n-butyrate, no compensatory absorption occurs during starvation. Under conditions in which luminal short-chain fatty acids are depleted, dietary fiber is useful as a low osmolality food constituent and for renewal of short-chain fatty acid levels by bacterial fermentation. The "antisecretory" effect of dietary fiber depends on the degree of the preexisting depletion of short-chain fatty acids and the methodology used to assess absorptive function. Dietary fiber has not been found harmful in refeeding starvation victims for whom it is an essential food constituent.

Animals↗
PubMedDate not supplied

Retinal nerve fiber layer measured by Heidelberg retina tomograph and nerve fiber analyzer.

PURPOSE: To compare retinal nerve fiber layer (RNFL) thickness measured by Heidelberg retina tomograph (HRT) and nerve fiber analyzer (GDx). METHODS: Twenty eyes of 20 consecutive healthy subjects were recruited for this study. Each subject had a normal visual field and a normal optic nerve head, which was assessed by slit-lamp biomicroscopy using a 90 degrees lens. Using the HRT and GDx, RNFL measurement was calculated as for software vs 2.01 and vs 1.0.14, respectively. Retinal nerve fiber layer thickness was evaluated for the entire annulus surface every 5 degrees degrees. RNFL was assessed by HRT and GDx. HRT RNFL measurement was calculated at 0 microm from the edge, while GDx RNFL measurement at 1.75 disc diameter as for software. The difference between the highest points and the deepest points was calculated and compared. Furthermore, because of the possibility of different scales in the two systems, the following ratio was calculated: superior/inferior, superior/temporal, superior/nasal, inferior/temporal, and inferior/nasal. RESULTS: When the entire RNFL thickness was considered, a significant (p<0.001) difference was found between the HRT and GDx measurements. A difference of 200 microm was found between the highest and the deepest HRT points while a difference of 40 microm was found between the highest and the deepest GDx points. CONCLUSIONS: HRT and GDx RNFL measurements were statistically different in each sector. However, ratio parameters showed no difference between the obtained values except for superior/temporal ratio and inferior/temporal ratio.

Aged↗
PubMed2004

Intraepidermal nerve fibers are indicators of small-fiber neuropathy in both diabetic and nondiabetic patients.

OBJECTIVE: Small-fiber neuropathies may be symptomatic yet escape detection by standard tests. We hypothesized that morphologic changes in intraepidermal nerves would correlate with clinical measures of small-fiber neuropathy. RESEARCH DESIGN AND METHODS: We studied 25 diabetic and 23 nondiabetic patients with neuropathy defined by signs, symptoms, and quantitative testing and 20 control subjects. Skin biopsies were obtained from forearm, thigh, proximal leg, and distal leg, and nerves identified using immunofluorescence with antibody to protein gene product (PGP) 9.5. RESULTS: Mean dendritic length (MDL) (P < 0.01) and intraepidermal nerve fiber density (IENF) (P < 0.001) progressively decreased from proximal to distal sites only in patients with neuropathy. There was a significant reduction in IENF when comparing control subjects and patient groups in the distal leg (P < 0.001). MDL was significantly decreased in the thigh (P < 0.005) and in the proximal (P < 0.01) and distal (P < 0.002) leg in patients compared with control subjects. IENF was not significantly altered in diabetic patients of <5 years' duration, but significantly decreased in patients with >5 years' duration. MDL showed a linear decrease with increasing duration of diabetes. Distal leg IENF showed significant negative correlations with warm (P < 0.02) and cold (P < 0.05) thermal threshold, heat pain (P < 0.05), pressure sense (P < 0.05), and neurological disability score total sensory (P < 0.03) and total neuropathy (P < 0.03) values. CONCLUSIONS: IENF was not significantly altered in these patients at <5 years' duration of diabetes, but fell significantly after 5 years of diabetes. MDL exhibited a linear loss with time, suggesting a different mechanism of change. MDL and IENF together may prove a useful end point in therapeutic trials for neuropathy.

Adult↗
PubMed1997

Substitution of neutral detergent fiber from forage with neutral detergent fiber from by-products in the diets of lactating cows.

Four lactating dairy cows that were ruminally and duodenally cannulated were used in an experiment with a 4 x 4 Latin square design to determine the effects of the substitution of neutral detergent fiber (NDF) from forage with NDF from wheat middlings, corn gluten feed, or a blend of distillers dried grains and hominy. Dietary crude protein and NDF averaged 18 and 31%, respectively, for the diet with 71.2% of the NDF from forage (control diet) and for diets with 55% of the NDF from forage (by-product diets). The substitution of NDF from these by-products for forage NDF did not affect dry matter intake (20.1 kg/d) or digestibility of organic matter. Total tract digestibility of acid detergent fiber was lower for cows fed the diet containing a blend of distillers dried grains and hominy than for cows fed the diet containing corn gluten feed. Microbial crude protein synthesis, milk production (23.9 kg/d), and milk fat percentage were similar for all cows, regardless of diet. Cows fed the diets containing wheat middlings or a blend of distillers dried grains and hominy had reduced ruminal pH compared with that of cows fed the diet containing corn gluten feed or the control diet. Diets containing 55% of total NDF from forage with 31% of total NDF from corn gluten feed, wheat middlings, or a blend of distillers dried grains and hominy can supply sufficient effective fiber to maintain normal ruminal function.

Ammonia↗
PubMed1998

Ash content of detergent fibers in feeds, digesta, and feces and its relevance in fiber digestibility calculations.

The influence of insoluble ash in diet, digesta, and fecal samples was evaluated. Ash-free values of neutral detergent fiber (NDF) and acid detergent fiber (ADF) for feed, digesta, and fecal samples were compared with uncorrected values of NDF and ADF in two digestibility experiments. Six feed samples were selected at random along with four duodenal and two fecal samples; the latter two were a part of two digestion studies. The silica composition of feed samples was low with the exception of oat hay and rice straw. Ash-free values of NDF and ADF for digesta and fecal samples were lower than uncorrected values of NDF and ADF, and silica accounted for the majority of the differences. The use of ash-free values of NDF and ADF in both digestibility experiments with dairy cows resulted in more realistic digestibility estimates and reduced the amount of variability associated with the calculation of the digestibility of NDF and ADF in the rumen and total digestive tract. The source of the insoluble ash was not identified but could have come from individual feedstuffs or the consumption of sand. Sample contamination by silica and other ash components may influence NDF and ADF composition if the fiber residues are not ashed prior to calculation of NDF and ADF.

Animal Feed↗
PubMed1986

Effects of rice fiber on fecal weight, apparent digestibility of energy, nitrogen and fat, and degradation of neutral detergent fiber in young men.

The effects of rice fiber on fecal weight, transit time, frequency of defecations, digestibility of nutrients and blood status were investigated in 5 healthy young men. Each of them consumed a brown rice diet and then a polished rice diet for 2 weeks respectively. Both diets contained 1.2 g protein per kg body weight. The brown rice diet contained 2 times as much dietary fiber as the polished rice diet. When they consumed the brown rice diet, it showed an increase of fecal weight and decrease of digestibility of energy, nitrogen and fat. Nitrogen balance was not significantly different and kept zero balance on both diets. Concentration of plasma cholesterol was not significantly different. The results suggest that rice fiber produced an increase in fecal weight, which is assumed to be effective in preventing colonic disease in advanced countries and does not affect plasma lipid level.

Adult↗
PubMed1976

[Quantitative studies on the regeneration of myelinated nerve fibers. I. Variations in the number and the size of myelinated fibers in the nerves of normal rats].

The number and size of myelinated nerve fibers have been determined at standard levels in the nerve to medial head of right and left gastrocnemius muscles of 24 normal rats (11 males and 13 females). The mean values of all results were comparable on right and left sides. Thus, 271 +/- 5 myelinated nerve fibers were found in the right nerve and 272 +/- 4 in the left; their mean diameter were respectively 8.1 +/- 0.1 and 8.0 +/- 0.1 micron. There were 60.1% of large nerve fibers on the right side and 59,9% on the left, their mean diameters being 10.5 and 10.6 micron. Some variations occured in all these values, depending of the weight and sex of the animals. Nevertheless, the differences between both sides of a same rat were negligible and the histograms of both nerves could be superposed. Accordingly, in the operated animals, the contralateral nerve may be used as control.

Animals↗
PubMed1982

Crude fiber determination using ceramic fiber to replace asbestos.

Crude fiber was determined in a wide range of feed products by a method which specifies ceramic fiber as a filter medium instead of the more hazardous and difficult to obtain asbestos. Results correlated well with those obtained by using AOAC official final action method 7.061-7.065 (correlation coefficient, 0.9994). For 8 samples, the coefficients of variation ranged from 0.74 to 4.80%. Compared with the AOAC method the proposed method showed a slight negative bias of 0.1%. Compared with asbestos, ceramic fiber was easier to prepare for use, filtering was faster, and samples bumped less.

Animal Feed↗
PubMedDate not supplied

Enzymatic-gravimetric determination in foods of dietary fiber as sum of insoluble and soluble fiber fractions: summary of collaborative study.

A collaborative study was conducted on an enzymatic-gravimetric method for determination of total dietary fiber in foods, in which soluble fiber and insoluble fiber are determined separately. Ten collaborators analyzed blind duplicate test samples from 5 food products: turnip, wheat bran, beans canned with tomato sauce, rice, and whole wheat bread. Repeatability and reproducibility relative standard deviations ranged from 1.48 to 14.73% and from 4.13 to 17.94%, respectively. The method was adopted first action by AOAC International.

Bread↗
PubMed1977

[Quantitative studies on the regeneration of myelinated nerve fibers. III. Variations in the number and size of regenerated fibers after localized freezing].

The number and size of myelinated nerve fibers have been determined at standard levels in the nerve to medial head of right and left gastroenemius muscles of 45 rats in which the left sciatic nerve had suffered an localized freezing. The nerves have been observed from 10 to 720 days after the operation. In the contralateral nerve, the number of myelinated fibers decreased in average to 18.8%, the mean diameter to 11,2%. Male rats appeared to be more sensitive than female to the effects of the operation. In the regenerating nerve, the number of myelinated fibers returned to normal during 4th week and later increased up to a mean of 124%. Their distribution became bimodal after the 60th day. Both histograms could be superposed by the 330th day and the mean diameter came back to normal soon afterwards.

Animals↗
PubMed2003

Relative influence of polymer fiber diameter and surface charge on fibrous capsule thickness and vessel density for single-fiber implants.

Single polypropylene microfibers plasma-coated with polymers of different surface charge [N,N-dimethylaminoethyl methacrylate (NN) (positive charge), methacrylic acid (MA) (negative charge), and hexafluoropropylene (HF) (neutral)] were implanted in the subcutaneous dorsum of Sprague-Dawley rats for 5-week intervals. Thee groups of fiber diameters were used: (I) 1.0 to 5.9 microm; (II) 6.0 to 10.9 microm; and (III) 11.0 to 15.9 microm. Fibrous capsule thickness and blood-vessel density (number of vessels within 100 microm of the fiber) were assessed in tissue sections in the planes of microfiber cross-sections. Results from a multifactorial analysis of variance demonstrated statistically significant main effects (p < 0.05) for microfiber diameter but not for surface-charge coating. The mean differences in capsule thickness among the microfiber diameter groups were: between groups II and I: 5.4 microm; between groups III and I: 10.2 microm; and between groups III and II: 4.7 microm. The mean differences in capsule thickness among surface-charge coatings were: between MA and NN: 0.7 microm; between MA and HF: 1.4 microm; and between NN and HF: 0.7 microm. Many of the 1.0 to 5.9 microm-in-diameter fibers had no capsule and no sign of a foreign-body reaction. For the vessel density analysis, neither microfiber diameter nor surface-charge coating had a statistically significant effect. Thus the geometric feature of microfiber diameter was more important than was surface charge relative to fibrous capsule formation but not relative to local vessel density. This ranking of the relative influence of design features in relation to tissue response provides useful information for prioritization in biomaterial design.

Animals↗
PubMed1999

XPS Analysis of Carbon Fiber Surfaces-Anodized and Interfacial Effects in Fiber-Epoxy Composites.

High strength carbon fibers were electrochemically treated in an aqueous ammonium carbonate solution, with increasing electric current density, using an original continuous treatment process. The electrochemical treatment induced a modification of the surface properties, i.e., surface functional groups as observed by XPS. As a result, the O1s/C1s and the N1s/C1s ratios of the fiber surfaces increased with the increase of current intensity of the electrochemical treatment in the interval of about 30-50 A m-2. However, no significant change in the surface functional activity characters was observed for strong treatments. Hence, a moderate treatment (30 A m-2) was sufficient to obtain optimum (O1s + N1s)/C1s ratios in this system. This treatment is possibly suitable for carbon fibers to be incorporated in a polar organic matrix, resulting in increasing the interlaminar shear strength (ILSS) of the resulting composites. Copyright 1999 Academic Press.

Journal Article↗