No description available.

More than half of all spinal cord injuries are anatomically incomplete, yet many of these result in complete loss of motor function below the level of injury. One approach to enhance functional recovery is to exploit spared CNS axons (that extend past the point of injury) to sprout and connect to potential targets. We have previously found that application of the neurotrophin; BDNF, to the sensory-motor cortex stimulates expression of regeneration associated genes such as GAP-43, and Tαl tubulin, and results in enhanced sprouting of injured corticospinal fibers rostral to the site of injury. Here, we investigated whether infusion of BDNF into the intact sensorimotor cortex induces sprouting of undamaged corticospinal fibers into denervated cervical spinal cord. We also studied the effect of this treatment using several behavioral tasks: gait analysis, forelimb inhibition during swimming, and food pellet reaching task. The results show that BDNF infusion into the intact sensorimotor cortex subsequent to a unilateral pyramidal lesion increases (3.2 fold) the sprouting of intact corticospinal fibers into the denervated, contralateral grey matter at the lumbar level of the spinal cord when compared with vehicle treated rats. This effect was not seen at the cervical level of the spinal cord. Functionally, unilateral pyramidal injury of corticospinal axons significantly increased toe spread of the contralateral denervated forelimb and hindlimb when compared to the uninjured side. BDNF treatment showed a recovery to presurgical levels. Testing of fine motor control with a food pellet reaching task demonstrated deficits in the impaired forelimb but did not show any improvement due to BDNF treatment.

No description available.

Pre-maturity <i>alpha</i>-amylase activity (PMAA) in the absence of sprouting is one of four causes of low Hagberg falling number (HFN) in UK winter wheat (<i>Triticum aestivum</i>), reducing the quality and value of milled flour. Other causes include the retention of pericarp <i>alpha</i>-amylase activity (RPAA), pre-maturity sprouting (PrMS) and post-maturity sprouting (PoMS). This thesis investigated the effects of environmental factors on PMAA which currently occurs in a variable and unpredictable fashion under UK weather conditions. A multi-site field experiment on four cultivars (Haven, Hornet, Pastiche and Riband), at four sites (Harper Adams University College, University of Nottingham, University of Aberdeen and ADAS-Bridgets) between 1994-1996 was undertaken to:- establish the frequency of the causes of low HFN; examine the relationship between grain drying-rate and PMAA; determine if it was possible to predict combine harvest HFN. A range of techniques including a visual sprouting assessment, fluorescein dibutyrate staining, iso-electric focusing and a beta-limit dextrin gel and iodine staining test were used to allow the cause of low HFN to be established. Of the forty crops analysed, 22 cases (45%) had detectable amounts of <i>alpha</i>-amylase activity. PMAA was identified solely in 2 cases (5%), in combination with PoMS in 8 cases (20%), in combination with RPAA in one case (2%), with PoMS occurring solely in 11 cases (28%). The HFN fell below the breadmaking standard of 250 s in 18 of the 36 site x year x cultivar combinations analysed. This was attributed solely to PMAA in two cases (11 %), a combination of PMAA and PoMS in a further eight cases (44%) and solely to PoMS in eight cases(44%). There were no cases where PrMS or RPAA reduced the HFN to below 250 s. The hypothesis that PMAA is related to the grain drying-rate between 40-20 % moisture content was tested. Grain drying-rate was determined by linear regression analysis using moisture content measurements made at regular intervals during grain development. In site x year x cultivar combinations where PMAA was detected the grain drying-rate was significantly (P = 0.047) lower (mean = 1.90 <i>cf</i>. 2.30% moisture loss day^-1), suggesting a slow grain drying-rate enhances PMAA. However, the low frequency of occurrence of PMAA in isolation prevented quantification of this relationship. Initiation of PMAA in the grain, was shown to occur from a grain moisture content of 47.8%. A pre-harvest sample taken by hand at 850 °C-days (35 % moisture, Zadoks growth stage 85-87) was shown to enable a prediction of combine harvest HFN to be made in the absence of subsequent rainfall and PoMS. The 95 % confidence limits associated with this HFN prediction were however wide. The hypothesis that transient changes in temperature early in grain development may affect PMAA, before the onset of any grain drying-rate effects, was tested in five controlled-environment cabinet experiments. Of 36 cultivar x time of transfer combinations undertaken from a 16/ 10°C to a 26 /20°C temperature regime, six led to a significant increase (P < 0.05) arid one led to a significant decrease in PMAA. Of the 18 cultivar x time of transfer combinations undertaken from a 25 / 20°C to a 16 / 10°C temperature regime, one led to a significant increase and one led to a significant decrease in PMAA. A comparison between the field and controlled-environment experiment results highlighted that after conditions putatively stimulating PMAA had been encountered, subsequent environmental factors, such as mean temperature and relative humidity may also affect PMAA. It was concluded that PMAA can be enhanced by transient increases in temperature before the grain reaches 40% moisture content and by a slow grain drying-rate between 40-20% moisture content. The variability in the results, however, also suggested other environmental factors were influencing PMAA.

More than half of all spinal cord injuries are anatomically incomplete, yet many of these result in complete loss of motor function below the level of injury. One approach to enhance functional recovery is to exploit spared CNS axons (that extend past the point of injury) to sprout and connect to potential targets. We have previously found that application of the neurotrophin; BDNF, to the sensory-motor cortex stimulates expression of regeneration associated genes such as GAP-43, and Tαl tubulin, and results in enhanced sprouting of injured corticospinal fibers rostral to the site of injury. Here, we investigated whether infusion of BDNF into the intact sensorimotor cortex induces sprouting of undamaged corticospinal fibers into denervated cervical spinal cord. We also studied the effect of this treatment using several behavioral tasks: gait analysis, forelimb inhibition during swimming, and food pellet reaching task. The results show that BDNF infusion into the intact sensorimotor cortex subsequent to a unilateral pyramidal lesion increases (3.2 fold) the sprouting of intact corticospinal fibers into the denervated, contralateral grey matter at the lumbar level of the spinal cord when compared with vehicle treated rats. This effect was not seen at the cervical level of the spinal cord. Functionally, unilateral pyramidal injury of corticospinal axons significantly increased toe spread of the contralateral denervated forelimb and hindlimb when compared to the uninjured side. BDNF treatment showed a recovery to presurgical levels. Testing of fine motor control with a food pellet reaching task demonstrated deficits in the impaired forelimb but did not show any improvement due to BDNF treatment. / Medicine, Faculty of / Graduate

No description available.

Call number: LD2668 .T4 1984 M67 / Master of Science

No description available.

Wheat and wheat products represent a major food staple consumed around the world. Asian noodles account for the end-use of at least twelve percent of all wheat produced globally. Whereas there has been extensive research into the role and significance of enzymes in the utilisation of wheat flour in bread-making, less is known of their role in Asian noodles. Accordingly, this study has been based on the hypothesis that some enzymes will have a significant impact on the quality characteristics of at least some styles of Asian noodle products. Five enzymes were selected for study: á-amylase, lipase, lipoxygenase, peroxidase and ascorbic acid oxidase. The focus has been on the processing of white salted and yellow alkaline styles of Asian noodles and the role of the enzymes in relation to the quality attributes of these products has been systematically investigated. The quality aspects encompass colour and colour stability, texture, cooking properties as well as structural characteristics of the products. As a part of the preliminary phases of the investigation, procedures for analysis and assessment of flours and noodles have been evaluated. In particular, for the textural properties of noodles, results were obtained with the TA-XT2 Texture Analyser using both a flat cylinder probe, to measure noodle hardness, and also a cutting blade measuring noodle firmness. In addition, various approaches were trialled for sample preparation and presentation in the use of scanning electron microscopy for the investigation of noodle structure. In order to measure the activity of the enzymes in flours and noodle products, assay procedures were set up and validated. These were then used for the analysis of a series of commercial flours and the levels of activity in each of the flours was relatively low indicating that they had been milled from wheat which had not been subjected to preharvest sprouting. á-Amylase was measured using the Ceralpha method and two different sources of exogenous á-amylase (bacterial and barley) were added to noodle formulations. In preliminary experiments various levels of á-amylase incorporation were compared and Abstract viii the impact on texture measured. Both sources of á-amylase resulted in softer noodle products. Adverse effects of the preparations on colour were observed in fresh noodles, although the differences were less obvious when noodles were cooked or dried immediately after preparation. Cooking losses were higher in noodles incorporating amylase, particularly the bacterial preparation. These impacts were reflected in changes in the appearance of starch granules in scanning electron micrographs of the noodles. Three different lipase preparations were studied and their incorporation had only minor effects on texture of noodles. Addition of wheat germ lipase resulted in slightly softer noodles, fungal lipase caused slightly harder noodles, while addition of porcine pancreas lipase gave harder noodles in the raw state and softer noodles after cooking. Similarly variable results were observed when colour and colour stability were evaluated, and there were no adverse effects upon cooking quality of Asian noodles. Two different preparations of horseradish peroxidase were investigated and both resulted in adverse effects on colour including at all stages of storage. One of the preparations resulted in softer noodles when texture was measured using the cylinder method and in firmer noodles when the blade attachment was applied. Neither the surface appearance of noodles nor the cooking properties were altered by the addition of peroxidase to the formulations. Different levels of addition of ascorbic acid oxidase from Cucurbita species showed only minor effects on characteristics for both styles of noodles. Incorporation of this enzyme resulted in lower lightness values but there was little effect on yellowness. Discolouration of noodle sheets was faster and more obvious at 25°C and compared to the storage of noodles at 4°C. The cooking qualities of noodles did not change upon addition of the oxidase. Activity of the enzyme lipoxygenase was measured spectrophotometrically using linoleic acid as substrate. Upon addition to the noodle formulations the enzyme preparation from soy bean resulted in slightly harder and firmer noodles. Colour and colour stability were not enhanced by the addition of lipoxygenase and significantly higher yellowness values were measured in some samples. This enzyme did not adversely impact upon the cooking or structural properties of either style of noodles. Abstract ix Some of the enzymes studied here demonstrated undesirable impacts on one or another aspect of noodle quality, particularly producing darkening or soft textural characteristics. Enzymes that might usefully be considered at lower levels of addition are ascorbic acid oxidase, porcine pancreas lipase and lipoxygenase. These three had no negative effects upon texture, structure or cooking quality of noodles. Visually the colour properties were not adversely impacted and instrumental assessment indicated brighter noodle sheet colours. At lower levels of addition, these three enzymes provide enhancement of noodle quality. On the other hand peroxidase, the two amylases and lipases affected the colour and colour stability of noodles. It was observed that the amylase preparations did result in pronounced softening of noodles. However, the data indicate that the adverse impact attributed to this enzyme when flour from sprouted wheat is used in noodle processing, are probably due to enzyme activities other than a- amylase.

No description available.