SEARCH · Search PubMed
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.
A longitudinally fiber-pumped, passively Q-switched Nd:YAG laser oscillator-power amplifier system is reported with which a maximum pulse energy of 68 mJ was achieved at high pulse stability, beam quality, and efficiency. Therefore, a compact fiber-coupling interface was developed for stacked arrays of quasi-cw diode lasers, providing a pump power of 1 kW at the fiber end.
Mechanisms whereby the olfactory system of the spiny lobster codes food odors were quantitatively analyzed. A 23-component chemical mixture, with a composition based on a tissue extract from a known food of lobsters, and 8 of the mixture's components were used to describe responses of single cells at two neural levels: a) olfactory receptor cells and b) low-order interneurons projecting from the main olfactory center of the brain. Cluster analysis identified six classes of narrowly tuned receptor cells. Interneurons, on the other hand, were significantly more broadly tuned than receptor cells and could not be grouped into a small number of discrete, highly correlated cell types. Nonetheless, some chemosensory interneurons (unimodal interneurons) had specificities as narrow as receptor cells. Across-neuron correlations between stimuli showed that the increase in neuronal breadth of responsiveness from the level of receptors to the level of interneurons was paralleled by an increase in similarity in across-neuron patterns and, therefore, a decline in ability to discriminate between any two compounds. Across-neuron correlations between concentrations of a given compound showed that stimulus quality had a much stronger effect on across-neuron patterns than did stimulus quantity and, hence, stimulus qualities could be distinguished in spite of concurrent changes in stimulus quantity. Coding of odor quality could be accomplished at the receptor level by a labeled-lines code. At the interneuronal level, odor quality appears to be coded by across-fiber patterns. However, the finding that unimodal interneurons were as narrowly tuned as receptor cells indicates that specific channels for some food-odor components (e.g., taurine and glycine) are conserved even at higher neuronal levels. These narrow-spectrum interneurons may have a special function in quality coding either by dominating the interneuronal across-fiber pattern for that stimulus or by being processed independently of the broad-spectrum interneurons and thereby transferring information about certain components by way of specific channels to even higher neuronal levels.
Good quality polarized Raman spectra of a single wool fiber and an intact feather barbule are presented. The intensity ratio of the alpha-helix component of the amide I band measured parallel and perpendicular to the wool fiber axis was 0.39 +/- 0.05. This is consistent with theoretical predictions based on orientational calculations using the normal Raman polarizability tensor for an alpha-helical amide I band where the protein strands are aligned roughly parallel with the fiber axis. However, the depolarized spectral intensity of the alpha-helix mode was greater than expected. For the feather barbule, despite high quality spectra, a unique orientation of the beta-sheet structure could not be determined using the Raman intensity ratios of the amide I band alone. Using previously developed methods, the protein chains were found to be oriented between 60 and 90 degrees from the long axis of the barbule compared to an angle of 51 degrees calculated from polarized IR spectra of the same barbule. The Raman tensor methods for the determination of protein orientation in these fibers was found to be constrained by the complexity of the materials and the limitations of the band fitting methods used to apportion the intensity among the various vibrational modes of their spectra. Other advantages and limitations of polarized Raman microscopic methods of structural determination are discussed.
A new sol-gel application for the development of SPME fibers is described. Phenyltrimethoxysilane (PTMOS) and methyltrimethoxysilane (MTMOS) were the sol-gel precursors used at different proportions, together with different water contents, catalyst and reaction time. It was observed that obtaining a good film quality was determinant for a good extracting fiber performance. The film thickness ranged 0.2-1 microm and could not be increased by multi-coating processes. Apparently, a dense, non-porous microstructure was obtained. These coatings exhibited a strong hydrophobic character, as shown by the capability of extraction of long chain and apolar aromatic compounds, which, was comparable to that of the 100 microm polydimethylsiloxane (PDMS) and 65 microm carbowax-divinylbenzene (CW-DVB). The developed fiber has shown high thermal (350 degrees C) and organic solvent stability (ethanol, toluene and dichloromethane), thus bearing adequate characteristics to be associated to GC and potentialities that may also envisage suitability for HPLC. The new fibers may be useful for the microextraction of non-polar compounds, although at trace levels and in simple matrixes only, due to the susceptibility to competition.
Animal performance on brassica diets often does not reflect laboratory estimates of the nutritive value of the herbage. Hay supplementation of brassica pastures should increase diet DM and fiber intake and dilute anti-quality factors. The optimal hay:brassica ratio needed to achieve desirable animal performance, however, has not been established. Effects of changing the hay:brassica ratio on feed and water intake, apparent digestibility of diets, thyroid status, and anemia were examined in five Dorset-cross wether spring lambs (initial BW 32.8 +/- 3.2 kg). The experimental design was a 5 x 5 Latin square with 21-d periods (7 d of adaptation, 6 d of intake measurement, and an 8-d digestion trial with jugular blood drawn on last day). Diets contained chopped grass hay and tyfon (turnip x Chinese cabbage hybrid) at five hay:tyfon ratios (DM basis): 100:0; 75:25; 50:50; 25:75; and 0:100. As the proportion of tyfon in the diet increased, there were linear increases (P < .05) in ad libitum DMI (922 to 1,359 g/d), total water intake (1.75 to 13.06 L/d), digestible DMI (401 to 952 g/d), and apparent digestibility of DM (55.9 to 86.3%), CP (52.9 to 84.5%), and neutral detergent solubles (57.2 to 88.5%). Hay plus tyfon diets exhibited negative associative effects for apparent digestibility of NDF, ADF, and cellulose. Plasma thyroxine and triiodothyronine, packed cell volume, red blood count, and hemoglobin concentration were not affected by diet. Tyfon influenced DMI and apparent digestibility of diets in a manner similar to that of a concentrate.
The chorda tympani nerve (CT) mediates taste from the anterior part of the tongue. Here we studied the effects of ethanol on the tongue in recordings from both the whole CT nerve and individual taste fibers of the rhesus monkey, M. mulatta. The response to ethanol consisted of a phasic and a tonic part. At the lowest concentration tested (0.3 M) ethanol gave a response in some animals and at 0.7 M in all animals. A sigmoidal function described best the relationship between nerve response and ethanol concentrations. Hierarchial cluster analysis with 26 nonalcoholic sweet, sour, salty, and bitter stimuli had earlier identified four types of taste fibers each responding predominantly to stimuli within one of the four human taste qualities. Here were found that ethanol stimulated all sweet-best fibers and at high concentration some salt-best fibers, but never any acid-best and bitter-best fibers. This may explain the sweet taste attributed to low ethanol concentration by humans. Further, in mixtures it suppressed the responses in acid-best and bitter-best taste fibers. This may partly explain the effects of ethanol on sour and bitter taste in alcoholic beverages.
Dairy cattle require fibrous feedstuffs in the diet. However, defining the fiber requirements requires knowledge of many interacting components within the diet as well as how the feed is allocated and processed. To meet the demands of high producing dairy cows for energy, diets consist of large quantities of concentrates and high quality forages containing relatively low amounts of fiber. However, to maintain normal rumen function and milk fat percentage, a large portion of the fiber needs to come from forage. Current National Research Council recommendations are a minimum of 25 to 28% dietary neutral detergent fiber, 75% of which is supplied from forage. Chemical measures of fiber alone are not adequate for ration balancing; fiber varies in its effectiveness at stimulating chewing. This variation is greater when feeds contain high amounts of by-products in place of forages. The effectiveness in stimulation of chewing of fiber is variable as the particle size and retention times of indigestible and digestible fiber vary. Currently, little information exists about the fiber requirements of the cow from immediately postcalving until peak lactation. Early lactation cows are clearly more limited by physical fill than are cows in mid and late lactation. Rations based on nonforage fiber sources (> 45% neutral detergent fiber on a dry matter basis) are being evaluated for early lactation cows. Information is needed to determine the variation in the amount of fermentation acids produced, chewing activity, and amount of saliva secreted as these all contribute to the physical effectiveness of fiber.
Persons with diabetes mellitus have an increased cardiovascular morbidity and mortality and therefore it is imperative to identify and treat aggressively all cardiovascular risk factors. The first line of intervention aiming to reduce the cardiovascular burden is dietary therapy along with other recommendations for lifestyle modification. Compliance with life-long dietary changes is a major issue and therefore emphasis should be placed on whole foods and dietary consumption habits. Also, dietary changes should be individualised according to patient's nutritional needs, lifestyle, cultural eating habits, taking into consideration all risk factors and existing comorbidities. Nevertheless, at least two main strategies have been proven to be effective in preventing coronary heart disease: 1). modification of fat quality through substitution of saturated fat, dietary cholesterol and trans- fatty acids with non-hydrogenated mono-and poly-unsaturated fats and increased consumption of omega-3 fatty acids; 2). modification of carbohydrate quality by choosing high-cereal fiber and low-glycaemic load intakes instead of refined grain products. Although the best diet for reducing cardiovascular risk remains uncertain, a combination of dietary interventions offers great benefits in preventing coronary events.
Human compact bone may be viewed as a fiber reinforced composite material in which the secondary osteons act as the fiber reinforcements. The cement line, which is the interface between the 'fibers' (osteons) and extraosteonal bone matrix, may impart important mechanical properties to compact bone. The nature of these properties is not known partly because the composition of the cement line is unknown. This analysis examines the constituents of the osteon cement line using scanning electron microscopy and X-ray microprobe analysis to address its biomechanical functions as a local interface. The analysis suggests that the cement line is a region of reduced mineralization which may contain sulfated mucosubstances. This composition is consistent with the hypothesis that the cement line provides a relatively ductile interface with surrounding bone matrix, and that it provides the point specific stiffness differences, poor 'fiber'-matrix bonding and energy transfer qualities required to promote crack initiation but slow crack growth in compact bone.
OBJECTIVE: To correlate the patient-derived physical function score, as measured by the disease specific Myasthenia Gravis Questionnaire (MGQ), and the score obtained with commonly used generic 36-item questionnaire, the Short-Form health survey (SF-36), with the degree of abnormal neuromuscular transmission measured by Single-Fibre EMG (SFEMG) and repetitive nerve stimulation (RNS) in Myasthenia Gravis (MG) patients. METHODS: SFEMG and RNS were performed in the deltoid muscle and SFEMG was also performed in the orbicularis oculi muscle in 45 MG patients. The patients were asked to fill out the MGQ, which has been translated and validated into Swedish, and the SF-36. The sum of MGQ items generates a global MGQ score. Items are also divided into 3 muscle specific domains: generalized, bulbar and ocular. RESULTS: The global MGQ score and generalized domain score of MGQ were strongly correlated with the degree of abnormal neuromuscular transmission, as measured by SFEMG in the deltoid muscle. Scores from ocular and bulbar domains of MGQ were not related to neurophysiological findings. Physical composite scores of SF-36 correlated significantly with the abnormal SFEMG findings in the deltoid. CONCLUSIONS: The degree of disturbed neuromuscular transmission in a proximal limb muscle correlates with a patient's subjective experience of generalized myasthenic dysfunction. SIGNIFICANCE: The observed correlation adds a new dimension to neurophysiological examinations in patients with MG.
Lens regeneration occurs in New Zealand albino rabbits after endocapsular lens extraction, if the anterior and posterior capsules remain relatively intact. Research beginning in the 19th century showed that regeneration of the lens begins as early as 2 weeks postoperatively, depends on the size of the capsulotomy and how it has scarred, and is faster in younger animals. More recently, implantation of embryonic ectoderm at the time of lens removal has been shown to improve the growth and quality of the regenerated lenses. Lens fiber differentiation follows a process similar to embryological development with proliferation of epithelial cells along the anterior and posterior capsule, elongation of the posterior epithelial cells, and differentiation into lens fibers. Signals required for lens fiber differentiation include FGF, IGF-1, and TGF-beta. Identifying other signals, and providing these factors to the regenerating lens, could speed up lens regeneration and improve normality of the resulting structure. The regenerated lenses contain the same proteins as normal lenses, including all the major crystallins (alpha, beta, and gamma). However, regenerated lenses have typically been irregular in shape due to lack of lens growth at the site of the anterior capsulotomy and its adhesion to the posterior capsule. Sealing the capsulotomy and refilling the bag to maintain its shape seem to allow for more normal lens regeneration. Lens regeneration is a potential approach to restoring normal vision after cataract surgery. Importantly, lenses have been shown to regenerate after removal of cataracts in several mammals, and primate lenses do have regenerative capability.
We describe a unique benign mesenchymal tumor in paraspinal location in a 13-year-old patient with Gardner's syndrome. The Gardner's syndrome in this patient consisted of multiple (more than 100) polyps throughout the entire colon with most in the cecum and rectum, three osteomas in the frontal area of the skull and one in the third right rib, and multiple superficial skin tumors. One of these cutaneous tumors was excised and histologically diagnosed as an epidermal cyst. Both father and uncle of this patient suffered from Gardner's syndrome as well. Microscopically the mesenchymal tumor was histologically different from nuchal type fibroma and fibromatosis. It consisted of a diffusely-growing fibrous mass composed of dense collagenous fibers and relatively numerous, bland-looking, spindle-shaped cells. The collagen fibers had haphazard spacing with no lobular arrangement. The collagen fibers were of a very coarse quality. No entrapment of adipose tissue, skeletal muscle or peripheral nerves was seen in the lesion. Immunohistochemically the tumor was vimentin positive and smooth muscle actin, muscle-specific actin, S-100 protein, cytokeratin and desmin negative.
The use of near-infrared (NIR) reflectance spectroscopy for the rapid and accurate measurement of soluble and insoluble dietary fiber was explored in a diverse group of cereal products. Ground samples were analyzed for soluble and insoluble dietary fiber (AOAC Method 991.43) and scanned (NIRSystems 6500 monochromator) to obtain NIR spectra. Modified PLS models were developed to predict insoluble and soluble dietary fiber using data sets expanded to include products with high fat and high sugar contents. The models predicted insoluble dietary fiber accurately with an SECV of 1.54% and an R(2) of 0.98 (AOAC determined range of 0-48.77%) and soluble dietary fiber less accurately with an SECV of 1.15% and an R(2) of 0.82 (AOAC determined range of 0-13.84%). Prediction of independent validation samples by the soluble fiber model resulted in a bias that may be related to the way the reference method treats samples with different soluble fiber constituents. The insoluble fiber model can be used to rapidly monitor insoluble dietary fiber in cereal products for nutrition labeling.
Dry beans are one of the inexpensive sources of reasonable quality proteins, carbohydrates, vitamins, minerals, and fiber. Their underutilization has been attributed to the presence of several factors, such as proteinase inhibitors, flatus factors, tannins, phytates, phytohemagglutinins, and the beany flavor. Removal of these unwanted components promises improved utilization of dry beans for human food purposes. The current methodology of removing these factors includes several food processing techniques such as soaking, dry and moist heat treatment, filtration, germination, and fermentation. The commercial feasibility of these processes will be discussed. The current lack of knowledge about deleterious effects of the residual components (remaining after processing) will be addressed and the needs for the future will be discussed.
Dry beans and soybeans are nutrient-dense, fiber-rich, and are high-quality sources of protein. Protective and therapeutic effects of both dry bean and soybean intake have been documented. Studies show that dry bean intake has the potential to decrease serum cholesterol concentrations, improve many aspects of the diabetic state, and provide metabolic benefits that aid in weight control. Soybeans are a unique source of the isoflavones genistein and diadzein, which have numerous biological functions. Soybeans and soyfoods potentially have multifaceted health-promoting effects, including cholesterol reduction, improved vascular health, preserved bone mineral density, and reduction of menopausal symptoms. Soy appears to have salutary effects on renal function, although these effects are not well understood. Whereas populations consuming high intakes of soy have lower prevalences of certain cancers, definitive experimental data are insufficient to clarify a protective role of soy. The availability of legume products and resources is increasing, incorporating dry beans and soyfoods into the diet can be practical and enjoyable. With the shift toward a more plant-based diet, dry beans and soy will be potent tools in the treatment and prevention of chronic disease.
Proficiency testing (PT) schemes seek to improve and maintain consistency in asbestos fibre counting by circulating mounted samples to laboratories, which return counts for comparison with consensus reference values. This study compares the level of these consensus values in three (Spanish, Belgian and UK) national PT schemes. It also assesses the effect of the imminent change in the European standard rules for counting asbestos fibres, to the new rules from the World Health Organisation (WHO), which will include more fibres. Forty samples from the three schemes were circulated to six laboratories, two in each national scheme. The UK and Spanish laboratories counted using both the ERM and the WHO method. Belgian laboratories already use the WHO method, and they counted only by this method. Densities from counts in this sample exchange served as a common basis against which we compared the national reference values (R). This produced a geometric overall mean ratio of R to exchange mean density of 0.94 for the UK scheme, 1.01 for the Spanish and 0.97 for the Belgian scheme, and thus indicated remarkably similar levels. Nevertheless, non-trivial systematic inter-laboratory differences confirmed the need for regular PT and international inter-laboratory comparisons. Examination of previous data from the national PT schemes and from an international scheme (AFRICA) provided further comparisons for the same laboratories (either comparing the laboratory's data with R values or making direct comparisons between laboratories) that are consistent with those from this special exchange. The change in fibre counting rule (to include fibres apparently touching particles with diameter >3 microm) produced mean increases in reported densities that ranged among samples from 0 to 70% (highest individual estimate 170%); the effect was broadly similar for the three schemes. The laboratories gave mostly similar estimates of percentage increase; however, one laboratory occasionally produced high estimates indicating a possible need for training for using the new method.
Three methods of classifying laboratories during fibre counting proficiency tests were compared. The first two are those used in France (classification according to the mean and coefficient of variation of the results) and in Great Britain (classification according to the proportion of normalized results situated within predefined limits). The third is a variation of the Workplace Analysis Scheme for Proficiency (WASP) programme adapted to fibre counting tests. In the latter case, the laboratory classification is based on comparing the variance characterizing the dispersion of the results of a laboratory with a reference variance, which is considered as the variance of experienced analysts or laboratories. This mode of processing has the advantage of allowing the comparison of magnitudes. For example, the variance of the reference value can be compared with the reference variance. The same applies if a proficiency test is organized on the basis of replicas distributed to different analysts, the variability of these replicas can be compared with the reference variance. It emerged that the modified WASP method produces results close to those obtained by the other two methods. Moreover, the selectivity of the three methods is evaluated.
Chemosurgical peel is a technique that has been used widely by plastic surgeons and dermatologists to remove fine and deep wrinkles of the skin. However, the reaction of elastic tissue to the cutaneous application of commonly used chemical peeling agents has not been defined. This study comparatively assessed the alteration in dermal histology and mechanical properties of skin following treatment with 25% and 50% trichloroacetic acid, Baker's phenol solution, and dermabrasion. Yucatan minipigs served as the animal model. The skin was analyzed at five intervals over 6 months after treatment using histologic, quantitative, and mechanical analysis (hematoxylin and eosin, elastic tissue, and Sirius red stains, computerized digital morphometry, and a tensiometer). At 6 months we found no change in the quality, structure, or arrangement of elastic fibers in skin treated with a single application of 25% and 50% trichloroacetic acid or dermabrasion when compared with untreated skin. Skin treated with Baker's phenol solution showed a marked morphologic change in the elastic fibers. The fibers within the regenerated zone of dermis were sparse, wispy, and immature at 6 months after treatment. Preliminary tensiometric analysis of phenol-treated skin at 6 months indicated that the skin was stiffer and weaker. This study questions the possibility of long-term change to the skin by the deep penetration of caustic chemicals to remove wrinkles and rejuvenate the skin.