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At least 19 recordsLinked to original sources
PubMed1979

Relationships among crude fiber, neutral detergent fiber, in vitro dietary fiber, and in vivo (rats) dietary fiber in wheat foods.

The in vivo dietary fiber contents of wheat milling fractions and wheat foods, determined in rat feeding experiments, were compared with dietary fiber values determined in vitro with pronase alpha-amylase digestion. Both types of dietary fiber values were compared with crude fiber and neutral detergent fiber values in the same materials. Regression analyses indicated close correlation amongst all values determined. It appears that laboratory analysis for crude fiber, neutral detergent fiber, or in vitro dietary fiber accurately predicts in vivo dietary fiber (rats) for wheat milling fractions when the laboratory result is adjusted by means of an appropriate regression equation.

Animals↗
PubMed1988

In vitro evaluation of the cytotoxic potential of a novel man-made fiber, calcium sodium metaphosphate fiber (Phosphate Fiber).

As part of a comprehensive effort to evaluate the toxicological potential of calcium sodium metaphosphate fiber (Phosphate Fiber), the in vitro cytotoxicity of the fiber in cultured cells was studied. Two pulmonary-derived cell systems (rat alveolar macrophages, RAM; rat lung epithelial cells, LEC) and an established cell line (Chinese hamster ovary, CHO) were used. Release of lactate dehydrogenase (LDH) was used as an endpoint for cytotoxicity for all three cell types. In addition, inhibition of colony formation was used for CHO cells. The cytotoxicity of Phosphate Fiber was compared to a variety of mineral dusts and fibers including chrysotile asbestos, crocidolite asbestos, two glass fibers, calcium sulfate fiber, titanium dioxide, as well as the nonfibrous raw material, calcium sodium metaphosphate glass. Results with all three cell culture systems demonstrated that the Phosphate Fiber was less cytotoxic than the two asbestos fibers, similar in cytotoxicity to the glass fibers, and more cytotoxic than the calcium sulfate fiber and titanium dioxide. To further investigate the cytotoxicity of the Phosphate Fiber, it was fractionated by sedimentation into small and large fibers. The small Phosphate Fiber was found to be more cytotoxic and the large Phosphate Fiber to be less cytotoxic than the unfractionated Phosphate Fiber. The in vitro data suggest that Phosphate Fiber is less cytotoxic than asbestos, but further determination of safety can only be made after the in vivo data have been obtained.

Animals↗
PubMed1988

Normal and regenerating optic fibers in goldfish tectum: HRP-EM evidence for rapid synaptogenesis and optic fiber-fiber affinity.

The distribution of normal and regenerating retinal fibers and synapses was studied on tectum in goldfish by light (LM) and electron microscopy (EM). Since labeling of the early regenerating fibers was previously reported to be difficult, a new 'cold-fill' HRP labeling protocol was developed, which labeled regenerating optic fibers and terminals on tectum as early as 14 days after nerve crush when they first arrive on tectum. In order to characterize the laminar distribution of optic afferents in normal fish and in fish regenerating for 14-240 days, EM photomontages of areas 14 microns wide by 160 microns deep through the HRP-labeled primary optic innervation layer (S-SO-SFGS) were constructed. The time points in regeneration that were examined spanned the period in which others have shown that an initially diffuse retinotopic map becomes spatially restricted. At the LM level regenerating optic fibers were restricted to the optic lamina. They reinnervated tectum in an anterior to posterior sequence as previously seen with autoradiography. In addition, at 14 days, some "pioneer" optic fascicles were found to have already grown to posterior tectum where they gave rise to branches with boutonlike terminations and growth-cone-like processes. Form the ultrastructural analysis it was clear that optic fibers and terminals observed strict laminar boundaries as they partitioned themselves in the optic laminae (S, SO and SFGS) in both normal and regenerating fish. The behavior of optic fibers was lamina specific with respect to synapse formation and the orientation of fiber outgrowth. As early as 14 days regeneration, optic fibers made synapses onto the four types of postsynaptic profiles observed in normal fish. Numerous optic terminals were labeled at 14 days, and there appeared to be no waiting period between fiber ingrowth to the SO and synapse formation in the S and SFGS. At 14-60 days, atypical synaptic contacts which appear to be nascent synapses were made by labeled optic fibers in fascicles and by growth-cone-like processes. By 21-30 days, the density of optic terminals was high and there were many more fasciculated optic fibers in the SFGS than normal as late as 350 days. These findings suggest that optic fiber lamination is highly constrained by tectal cues, that fibers rapidly regenerate many synaptic terminals before retinotopic map refinement is complete, and that fibers have a strong affinity for each other.

Animals↗
PubMed1990

Dietary fiber for dogs: II. Iso-total dietary fiber (TDF) additions of divergent fiber sources to dog diets and their effects on nutrient intake, digestibility, metabolizable energy and digesta mean retention time.

The objectives of this study were to examine widely divergent fiber sources for their efficacy as ingredients in a meat-based dog diet and to determine the effects of these fibers on fecal excretion responses and mean retention time of marked fiber in the gastrointestinal tract of the dog. Fiber sources tested included beet pulp (BP), tomato pomace (TP), peanut hulls (PH), wheat bran (WB) and alkaline hydrogen peroxide-treated wheat straw (AHPWS). Diets were isonitrogenous (5.3% N) and iso-total dietary fiber (TDF; 12.5%). Thirty female English Pointers (five/treatment) were used in the experiment. Intakes of DM and OM were similar among treatments. The highest intakes of ether extract (EE) occurred on the TP, PH and WB treatments. Dogs fed PH ingested the most crude fiber (23.6 g/d), NDF (53.5 g/d), ADF (34.3 g/d) and TDF (59.7 g/d). Digestibilities of DM and OM for all fiber treatments were lower than the control (87.6 vs 81.8% for DM; 90.2 vs 85.4% for OM), but values were similar among fiber sources. The highest EE and N digestibilities occurred on the control and AHPWS treatments. No differences were noted among exogenous fiber-containing treatments in fiber component digestibility. Digestible energy and ME values generally were similar among treatments. Among fiber sources, BP resulted in the greatest amount of wet feces excreted (270 g/d) and the lowest fecal DM (30.3%). No differences among fiber sources were noted in frequency of defecation or mean retention time. Iso-TDF diets (containing, on average, 12.5% TDF) appear to be utilized similarly, regardless of the diversity in sources of fiber tested.

Animal Feed↗
PubMed1992

[The three-dimensional ultrastructure of the collagen fibers, reticular fibers and elastic fibers: a review].

Fibrous components of the connective tissue are light-microscopically classified into three types: collagen fibers, reticular fibers and elastic fibers. The present paper reviews the three-dimensional ultrastructure of these fibrous components, mainly based on our studies by scanning electron microscopy. The collagen fibers are shaped like tapes or cords about 1 to 20 microns in diameter. Each fiber is a bundle of fibrils running roughly parallel to each other. These collagen fibrils vary in diameter from 30 to 300 nm depending on their locating area of the body, and show a repeating pattern of depressed and protruding segments on the surface. The reticular fibers consist of collagen fibrils about 20-40 nm in diameter, which run singly or in small bundles. They are usually interwoven elaborately to form thin lace-like sheets or sheaths attaching to basal laminae of such cells as epithelial, endothelial and muscular cells. These fibers are considered to play an important role not only in adhering the cells to the collagen fibers, but also in constituting the skeletal framework suitable for individual cells and tissues. The elastic fibers consist of two different components: elastin and fibrillin. Elastin forms unit fibrils of 0.1-0.2 micron thickness which are arranged in bundles or laminae specific to individual organs and tissues. Fibrillin, on the other hand, forms microfibrils about 10 nm in diameter running in or along elastin bundles. These microfibrils also form delicate networks separate from elastin components. For a comprehensive understanding of the fibrous components in the connective tissue, the author proposed categorizing them into two systems: the collagen fibrillar system as a supporting framework of tissues and cells, and the fibrillin-elastin fibrillar system for distributing stressing forces uniformly in tissues.

Connective Tissue↗
PubMed1985

Dietary fiber in pancreatic disease: effect of high fiber diet on fat malabsorption in pancreatic insufficiency and in vitro study of the interaction of dietary fiber with pancreatic enzymes.

The effect of high fiber diet on fat malabsorption was evaluated in twelve patients with exocrine pancreatic insufficiency secondary to chronic alcoholic pancreatitis. Additionally, the effect of dietary fiber on pancreatic enzymes was examined in vitro, employing different concentrations of cellulose, pectin, and wheat bran incubated with amylase, lipase, and trypsin. Ingestion of a high fiber diet was associated with a small but significant (p less than 0.01) increase in fecal weight and fecal fat excretion. All patients complained of increased abdominal flatulence with high fiber diet, however, no significant increase in frequency of bowel movements was noted. In vitro studies demonstrated reduction in pancreatic enzyme activity by increasing concentration of dietary fiber and its components. These data suggest that steatorrhea may be enhanced with the ingestion of high fiber diet in patients with exocrine pancreatic insufficiency on oral pancreatic enzyme therapy. Increase in fecal fat excretion may, in part, be related to reduction in the activity of pancreatic enzymes by the dietary fiber.

Adult↗
PubMed1989

[Morphological changes in human diaphragm--ragged red fiber, core/targetoid fiber, cytoplasmic body, and ring fiber].

We have already described that ragged red fiber (RRF), core/targetoid fiber and type 1 fiber predominance were found at autopsy in the diaphragm taken from patients with chronic obstructive pulmonary diseases. The purpose of the present study is to investigate morphological and histochemical changes in the diaphragm in denervating neurologic disorders. The diaphragm in the costal portion was taken from 22 autopsy cases including 4 with amyotrophic lateral sclerosis (ALS), 4 cerebrovascular diseases, 3 Parkinson disease, 2 olivopontocerebellar atrophy. In addition, 4 diaphragm muscles were biopsied at the time of surgery for lung cancer. In the diaphragm we observed not only RRF and core/targetoid fiber but also cytoplasmic body and ring fiber in many cases. These findings were, however, not specific for neurologic disorders. Focal cytochrome c oxidase deficiency was found in muscles with RRF. It should be emphasized that RRF was absent in 3 of 4 cases with ALS and in a case with elevated hemidiaphragm from phrenic nerve paralysis. In the previous report, we suggested that RRF was formed under the relative ischemic state in overworking diaphragm. The relative ischemia means a condition that oxygen (energy) demand for respiratory work exceeds over oxygen supply from the blood in the overworking diaphragm. The reason why no RRF was found in the denervated muscle is that the ischemic state in the denervated muscles is relieved by immobilization after denervation. Karpati et al conformed that denervation prevented ischemic state in the muscle. Other histochemical features in the diaphragm included cytoplasmic body and ring fiber.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytochrome-c Oxidase Deficiency↗
PubMed1990

The relationship between ventral striatal efferent fibers and the distribution of peptide-positive woolly fibers in the forebrain of the rhesus monkey.

Peptidergic fibers in the globus pallidus of the monkey appear in the morphological form referred to as woolly fibers. These fibers are composed of a dense plexus of thin beaded axons which ensheath an unstained central core. Such structures are not confined to the globus pallidus, but are also present in the bed nucleus of the stria terminalis, the hypothalamus, the dorsal part of the amygdala, and ventrally in the basal forebrain. The present study describes the relationship between projections from the rostral and ventral striatum and the enkephalin- and substance P-positive woolly fibers. Following injections of either tritiated amino acids or the lectin Phaseolus vulgaris-leucoagglutinin in the ventral striatum, anterogradely labeled fibers and terminals in the forebrain were visualized simultaneously with enkephalin- or substance P immunoreactivity in the same tissue section in order to determine: (i) the extent to which the woolly fiber distribution represents striatal output systems; (ii) whether woolly fibers can be considered as a marker for the entire striatal forebrain projection; and (iii) whether enkephalin and substance P are involved differentially in distinct ventral striatopallidal pathways. Phaseolus vulgaris-leucoagglutinin labeling is seen in the globus pallidus and adjacent structures either as single, beaded fibers or in a profile strikingly similar to that of woolly fibers. In tissue sections treated for a double immunohistochemical protocol, following which the Phaseolus vulgaris-leucoagglutinin-immunoreactive fibers turn black and the peptidergic woolly fibers brown; many of the lectin-positive fibers are seen to enter the peptide-positive woolly fiber plexus. Likewise, following the injections with tritiated amino acids in the ventral striatum, coarse structures that have dimensions resembling those of the woolly fibers are identified. In sections immunohistochemically stained and subsequently treated for autoradiography, peptide-positive woolly fibers can be identified underlying the silver grains. In sections stained for both peptide immunoreactivity and tracer substances, enkephalin or substance P-positive woolly fibers are present in all pallidal regions that receive ventral striatal input. However, the ventral striatum also sends fibers to the hypothalamus, bed nucleus of the stria terminalis, the dorsal part of the amygdala, the septum, the preoptic area, and other areas of the basal forebrain. In these nuclei the peptide-positive woolly fiber distribution is less extensive than the terminal labeling. The distribution of substance P-positive fibers in the subcommissural pallidal region is more limited than the distribution of enkephalinergic fibers.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Histochemical, biochemical, and ultrastructural analyses of single human muscle fibers, with special reference to the C-fiber population.

A muscle biopsy from the vastus lateralis muscle of a strength-trained woman was found to contain an unusual fiber type composition and was analyzed by histochemical, biochemical, and ultrastructural techniques. Special attention was given to the C-fibers, which comprised over 15% of the total fiber number in the biopsy. The mATPase activity of the C-fibers remained stable to varying degrees over the pH range normally used for routine mATPase histochemistry. Although a continuum existed, the C-fibers were histochemically subdivided into three main fiber types: IC, IIC, and IIAC. The IC fibers were histochemically more similar to the Type I, the IIAC were more similar to the Type IIA, and the IIC were darkly stained throughout the pH range. Biochemical analysis revealed that all C-fibers coexpressed myosin heavy chains (MHC) I and IIa in variable ratios. The histochemical staining intensity correlated with the myosin heavy chain composition such that the Type IC fibers contained a greater ratio of MHCI/MHCIIa, the IIAC contained a greater ratio of MHCIIa/MHCI, and the Type IIC contained equal amounts of these two heavy chains. Ultrastructural data of the C-fiber population revealed an oxidative capacity between fiber Types I and IIA and suggested a range of mitochondrial volume percent from highest to lowest such that I greater than IC greater than IIC greater than IIA-C greater than IIA. Under physiological conditions, it appears that the IC fibers represent Type I fibers that additionally express some fast characteristics, whereas the Type IIAC are Type IIA fibers that additionally express some slow characteristics. Fibers expressing a 50:50 mixture of MHCI and MHCIIa (IIC fibers) were rarely found. It is not known whether C-fibers represent a distinct population between the fast- and slow-twitch fibers that is specifically adapted to a particular usage or whether they are transforming fibers in the process of going from fast to slow or slow to fast.

Adult↗
PubMed1989

Retinogeniculate projection fibers in the monkey optic nerve: a demonstration of the fiber pathways by retrograde axonal transport of WGA-HRP.

Seven Japanese monkeys (Macaca fuscata) were used to investigate the fiber pathways of the optic nerve. Optic nerve fibers and retinal ganglion cells were retrogradely labeled by iontophoretic injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into electrophysiologically defined positions of the lateral geniculate nucleus (LGN). By gross anatomical observation, the optic nerve usually had one distinct bend, which flexed dorsally 3-4 mm from the eyeball, and occasionally another ventrally directed bend was found just behind the eyeball. In the optic nerve head, fibers from the various retinal areas were arranged in a wedge according to the fiber trajectory on the retinal surface. For about a 3 mm distance from the disc, fibers rapidly spread out radially. Subsequently, rather than scattering dorsoventrally, they progressed to the chiasm with a gradual increase in the degree of mediolateral (nasotemporal) scatter. The degree of the scatter was different depending on the retinal site from which the axons originated. Fibers from the peripheral retina spread out widely for a few millimeters behind the eyeball. Thereafter the scatter was rather limited until the chiasm. On the other hand, the scatter of fibers from the foveal and parafoveal areas progressed gradually through the nerve. The present study also suggests that the difference in scatter depends on the types of cells of origin. Fibers from large ganglion cells displayed more extensive scatter than fibers from medium-sized cells. In spite of the extensive scatter of fibers, two clear segregations were found; one was a dorsoventral segregation, which was displayed by both central and peripheral retinal fibers, and the other was a center-peripheral segregation in which the fibers from the nasal central (papillomacular) retina were located almost exclusively in the central part of the optic nerve surrounded by peripheral retinal fibers. However, the temporal central retinal fibers were located in the lateral periphery of the nerve, and they overlapped significantly with fibers from the temporal peripheral retina. Furthermore, a broad intermingling was found between nasal and temporal peripheral retinal fibers owing to their mediolateral scatter. Thus, the present findings based on more precise anatomical techniques indicate that the classical notion of the retinal quadrant topography in the monkey optic nerve probably is suspect. In addition, the "rotation" of the fiber arrangement was not demonstrated.

Animals↗
PubMed1990

Fiber-type specific caffeine sensitivities in normal human skinned muscle fibers.

Caffeine sensitivity was studied in chemically skinned muscle fibers from vastus lateralis muscle obtained by biopsy during reconstructive knee surgery from 15 otherwise healthy young individuals. Muscle fiber type was determined by contracture occurring in strontium (slow-oxidative, type I fiber) or calcium (both type I and type II, fast glycolytic fiber) solutions and in several fibers after contracture testing by ATPase enzyme histochemistry. Caffeine sensitivity (mean +/- SD), defined as the threshold concentration inducing more than 10% of the maximal tension obtained with a calcium 3 x 10(-5) mM solution was 2.7 +/- 1.3 mM in 37 type I fibers, whereas it was 6.9 +/- 2.4 mM in 61 type II fibers. A paired t test showed a significantly increased sensitivity to caffeine in type I fibers (P less than 0.001) in 13 individuals in whom the two fiber types were identified. The mean (+/- SD) difference between type I and type II fibers was 4.1 +/- 1.9 mM. Type I fibers contracted with greater tension in response to the increasing concentration of caffeine than did type II fibers (P less than 0.05). These skinned fiber studies showed significantly different caffeine sensitivities between human type I and type II muscle fibers, as previously shown in animal muscles. The findings that human type I muscle fibers have higher caffeine sensitivity than type II muscle fibers should be helpful for the interpretation of the in vitro contracture test done in muscle strips containing type I and type II fibers in varying proportions.

Adenosine Triphosphatases↗
PubMed1976

Myosin-free ghosts of single fibers and an attempt to re-form myosin filaments in the ghost fibers.

With the final aim of replacing myosin in a single muscle fiber, a technique for removing myosin almost completely from single fibers was developed and an attempt to "re-form" thick filaments in the myosin-free ghosts of single fibers was made. Complete removal of myosin from single glycerol-treated rabbit psoas fibers with Hasselbach-Schneider solution was difficult. However, when skinned glycerol-treated fibers were used and 1% (v/v) Triton X-100 was added to the Hasselbach-Schneider solution, almost complete removal of myosin was possible. The myosin-free ghosts of skinned single fibers were very fragile but retained the overall structure. In the ghost fibers, Z-membranes and thin filaments remained. The ghost fibers, after irrigation with myosin, underwent contraction upon addition of Mg-ATP. In the myosin-irrigated fibers, thick filaments were re-formed in lengths from one Z-membrane to the other Z-membrane of a sarcomere, running parallel to the thin filaments. The packing of these two filaments was not good. The isometric tension developed by the irrigated fibers upon addition of mg-ATP was about 10% of the tension developed by untreated fibers. The weak tension developed by irrigated fibers is probably due to the irregular packing of the thick and thin filaments in the fibers. The ghost fibers also contracted, though only slightly, upon addition of Mg-ATP after irrigation with heavy meromyosin.

Adenosine Triphosphate↗
PubMed1987

Fiber types and fiber diameters in canine respiratory muscles.

In the present study, we measured fiber types and fiber diameters in canine respiratory muscles and examined regional variation within the diaphragm. Samples of eight diaphragm regions, internal intercostals, external intercostals, transversus abdominis, and triceps brachii were removed from eight adult mongrel dogs, frozen, and histochemically processed for standard fiber type and fiber diameter determinations. The respiratory muscles were composed of types I and IIa fibers; no IIb fibers were identified. Fiber composition differed between muscles (P less than 0.0001). Normal type I percent (+/- SE) were: diaphragm 46 +/- 2, external intercostal 85 +/- 6, internal intercostals 48 +/- 3, transversus abdominis 53 +/- 1, and triceps 33 +/- 7. The diaphragm also contained a type I subtype [6 +/- 1% (SE)] previously thought only to occur in developing muscle. Fiber composition varied between diaphragm regions (P less than 0.01). Most notably, left medial crus contained 64% type I fibers. Fiber size also varied systematically among muscles (P less than 0.025) and diaphragm regions (P less than 0.0005). External intercostal fiber diameter was largest (47-50 microns) and diaphragm was smallest (34 microns). Within diaphragm, crural fibers were larger than costal (P less than 0.05). We conclude that there are systematic differences in fiber composition and fiber diameter of the canine respiratory muscles.

Analysis of Variance↗
PubMed1990

Mormyromast electroreceptor organs and their afferent fibers in mormyrid fish. III. Physiological differences between two morphological types of fibers.

1. Mormyromast electroreceptor organs in electric fish of the family Mormyridae have two types of separately innervated sensory cells, the A and B sensory cells of Szabo and Wersall. The first paper in this series showed anatomically that afferent fibers from the two types of sensory cell terminate centrally in separate zones of the electrosensory lateral line lobe (ELL), fibers from A cells terminating in the medial zone and fibers from B cells terminating in the dorsolateral zone. The goal of the present study was to determine the physiological differences between the two morphologically distinct types of mormyromast afferent fibers. 2. The present study has two parts. In the first part, mormyromast fibers were recorded near their central terminals in the two mormyromast zones of ELL. In the second part, mormyromast fibers were recorded from a peripheral electrosensory nerve. In both parts, various electrosensory stimuli were delivered and voltage thresholds were measured at the electroreceptor. 3. In the first part of the study, mormyromast fibers terminating in the two central zones were found to be different in their thresholds and in the maximum number of spikes evoked by a single stimulus. Afferent fibers terminating in the medial zone, which arise from A sensory cells, had higher thresholds and smaller maximum spike numbers than fibers terminating in the dorsolateral zone, which arise from B sensory cells. 4. In the second part of the study, the same two groups of fibers--one group with a high threshold and a small maximum spike number, and a second group with a low threshold and a large maximum spike number--were identified in extracellular recordings from a peripheral electrosensory nerve. The thresholds of the two groups were quite distinct, allowing the fibers to be divided into high- and low-threshold groups, which most likely represent the fibers from the A and B sensory cells, respectively. 5. The high- and low-threshold groups of fibers recorded from peripheral nerve were found to be different in a number of additional properties besides threshold and maximum spike number. Additional differences were found in the following properties: strength-duration curve, correlation with a receptor potential recorded at the electroreceptor, tuning curve, and short latency facilitation by a conditioning stimulus. Thus there appear to be several physiological differences between mormyromast afferent fibers from A and B sensory cells, in addition to the differences in threshold and spike number.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Response dynamics of goldfish saccular fibers: effects of stimulus frequency and intensity on fibers with different tuning, sensitivity, and spontaneous activity.

The effects of stimulus frequency and intensity on response patterns (PST histograms) to tone burst stimulation were examined in differently tuned saccular fibers of the goldfish. In addition, the sensitivity of these fibers to amplitude-modulated (AM) signals of different carrier frequencies was measured. The response patterns evoked by unmodulated signals were a complex function of tuning, spontaneous activity and sensitivity of the fiber, and the frequency and intensity of the signal. Frequency-dependent response patterns were found in low-frequency fibers with best frequencies (BF) below 200 Hz. Responses in these fibers ranged from tonic to phasic in nonspontaneous fibers and included more complex patterns in spontaneously active fibers, such as suppression of evoked activity below spontaneous levels. Midfrequency fibers (BF = 500-600 Hz) showed responses similar to those in low-frequency fibers, but with less dependence on frequency. In contrast, both high-frequency (BF = 800-1000 Hz) and wideband, untuned fibers showed frequency-invariant patterns of adaptation. High-frequency fibers were equally sensitive to AM signals at all frequencies tested. The sensitivity of low-frequency fibers to AM, however, increased as a function of carrier frequency and corresponded to the degree of adaptation in response to unmodulated tones. In general, the AM sensitivity of a fiber could be predicted more by its pattern of response to unmodulated signals than by its tuning characteristics.

Acoustic Stimulation↗
PubMed1990

Risks associated with source of fiber and fiber components in cancer of the colon and rectum.

In this case-control study, we examined the food sources of fiber and fiber solubility to determine whether particular components of dietary fiber were differentially associated with risk of colon and rectal cancer. In Western New York, cases with pathologically confirmed, single, primary cancers of the colon and rectum as well as age-, sex- and neighborhood-matched controls were interviewed from 1975-1986. The sample included 428 colon case-control pairs (223 females, 205 males) and 422 rectal case-control pairs (145 females, 277 males). Subjects were interviewed regarding usual quantity and frequency of consumption of foods. For the colon, risk decreased with intake of grain fiber for both females and males and with intake of fruit/vegetable fiber for males only. Insoluble grain fiber was more strongly associated with risk than soluble grain fiber. For the rectum, fruit/vegetable fiber was associated with decreased risk, whereas grain fiber was not. There was no difference in risk for soluble and insoluble fiber components for the rectum. Analysis of risk associated with fiber by food source and by components of the fiber may provide insight into possible mechanisms of a fiber effect on cancer of the colon and rectum.

Colonic Neoplasms↗
PubMed1991

Fatigue in type I fiber predominance: a muscle force and surface EMG study on the relative role of type I and type II muscle fibers.

The relative proportions of fiber types within muscle and the characteristics of these fiber types are important determinants of the surface electromyogram (SEMG) during fatigue. In this study, patients suffering from congenital myopathy characterized by a strong type I fiber predominance were studied. Six patients with 95-100% type I fibers, 2 patients with 80% type I fibers, and 12 healthy volunteers participated in an ischemic, isomeric, intermittent exercise test of m. quadriceps femoris at 80% MVC. Considering the results of the morphometric analysis of muscle biopsy specimen and of the anthropometric estimated muscle-bone volume, it was found that type I muscle fibers had a lower force generating capacity than type II fibers. The initial conduction velocity along the muscle fiber membrane (MFCV) was low in patients with 95-100% type I fibers. During the ischemic exercise test, the 95-100% type I fibers showed less fatigability than type II fibers, which was reflected by a nearby absent decrease of the muscle membrane excitability as measured by the MFCV, and only a slight increase of the SEMG amplitude compared with patients having 80% type I fibers and controls. The absence of a definite MFCV decrease was related to the nearby lacking lactate formation in 95-100% type I fibers.

Adolescent↗
PubMed1986

Muscle fiber type transformation in nemaline myopathy and congenital fiber type disproportion.

In a morphometric study on biopsied muscles from 5 patients with nemaline myopathy (NM) and 5 with congenital fiber type disproportion (CFTD), the common findings were relative type 1 fiber smallness, type 1 fiber predominance and occasional hypertrophic type 2 fibers. In NM, the relatively larger type 1 fibers increased in number with age in parallel with a decrease in the number of normal to hypertrophic type 2 fibers, reflecting active fiber type transformation from type 2 to type 1, which resulted in striking type 1 fiber predominance. The presence of scattered non-atrophic type 2C fibers also reflected active fiber type transformation because the fibers during the maturational or degenerating process are known to show the type 2C reaction on ATPase staining. On the other hand, the type 1 fibers in CFTD were small in caliber and showed minimal variation in size, suggesting practically no fiber type transformation from hypertrophic type 2 to type 1.

Child↗