Search

The effects of tea polyphenols and ultraviolet radiation on the growth and antioxidant activity of mung bean sprouts were investigated, followed by the changes in corresponding antioxidant enzyme activities and metabolite composition. The growth of mung bean sprouts was slightly decreased by tea polyphenols and ultraviolet radiation, but the antioxidant activity was increased. The activities of peroxidase and catalase were decreased, and the contents of vitamin C, γ-aminobutyric acid and total phenols were significantly increased by tea polyphenol treatment. While the activities of peroxidase and catalase increased by ultraviolet radiation with concomitant increase in the contents of vitamin C and total phenols. The mung bean sprouts produced following imposition of stressors such as tea polyphenols and ultraviolet radiation from stress conditions could be used as a potential functional food.

Performance of Lactococcus lactis as a starter culture in food production largely depends on the use of lyoprotectants during lyophilization. Gradient-freezing of bacterial cultures was conducted at 4°C, −20°C, and −80°C by storing the samples at each temperature for 2 h, successively. The entocytes extracted from the frozen cells were used as a lyoprotectant in the follow-up freeze-drying process of Lactococcus lactis subsp. lactis IL1403. The cell survival rate of gradient-freezing group increased 6.4-fold by bacterial plate count method. Furthermore, a proteomics and bioinformatics method was applied to elucidate the protein changes of Lactococcus lactis subsp. lactis IL1403 in response to gradient-freezing by gel-free proteomics using tandem mass tags (TMTs). The results showed that 121 stress-related proteins were significantly influenced by gradient-freezing. These proteins were involved in several metabolism pathways including ribosome metabolism, amino acid metabolism, quorum sensing, phosphotransferase system (PTS), pentose phosphate pathway, microbial metabolism in diverse environments, and nitrogen metabolism, etc. Some of these proteins especially the up-regulated proteins are potential lyoprotectants in vitro and they still need to be further investigated.

Transplants of olfactory ensheathing cells (OECs) from olfactory bulbs have recently been shown to support regrowth and reinnervation of damaged spinal cord, which has led to improved functional recovery. Using complete transection in adult rat, the studies presented in this thesis examine the role of peripherally derived olfactory tissue in promoting axonal regeneration and functional recovery. Chapter One and Two provide the background to the area of spinal cord regeneration and the methods used in this thesis. Chapter Three shows that transplants of OECs from rat olfactory lamina propria (OLP) are able to support axon regrowth in the lesioned spinal cord. The BBB score was significantly higher in experimental rats (5.4–0.84) compared with control animals (1.9–0.33) (P&lt0.001). These dissociated OECs from OLP can promote axonal regrowth through the lesion. Histological assessment showed that: 1) axons labelled with Fluororuby grew into the injury site in OECs-transplanted rats, with occasional fibres extending into the rostral cord; 2) brainstem neurons in the raphe nucleus were retrogradely labeled with Fluororuby; and 3) serotonergic axons were detectable distal to the lesion in OECs-transplanted rats. No fibres grew into the injured region and no retrograde labeling or serotonergic fibres were seen in control animals. The role of regenerated serotonergic fibres in OECs-transplanted rats is discussed. Chapter Four demonstrates that solid pieces of OLP dissected from the nose can re-establish the continuity of the transected cord and supply the OECs that can migrate to the cord stumps to support the axon regeneration. Experimental rats which received OLP from olfactory mucosa showed significantly greater locomotive recovery (BBB scores: OLP, 5.0–1.9; control, 1.5–0.5, p&lt0.0001). In animals with OLP transplants, histological analysis indicated that nerve fibres, expressing neurofilament and serotonin were present at the transection site. Locomotive recovery of the hindlimbs occurred, similar to that seen after OECs transplantation. Retrograde labeling of medullary raphe neurons and gigantocellular reticular nucleus occurred following Fluororuby injection in the cord distal to the lesion, further supporting the supraspinal origin of the 5-HT innervation in the present studies. These results indicate that OLP is effective in promoting partial spinal cord repair. Chapter Five examines functional recovery of spinal reflex circuitry, ie., H-reflex excitability using paired stimuli, in OLP-transplanted rats compared with normal and respiratory lamina propria (RLP) transplanted animals. H-reflex amplitude of the conditioned response was significantly reduced in OLP transplanted rats compared to RLP transplanted animals (p&lt 0.05). Therefore, hindlimb reflex excitability can be modulated by OLP transplants after transection of the spinal cord in adult rats. Chapter Six examines whether functional recovery can occur if transplantation of OLP tissue is delayed by 1 month after the spinal cord transection. The BBB score was significantly higher in experimental rats (4.3–0.8 for OLP) compared with control animals (1.0–0.3, P&lt 0.001), but recovery was less than after acute transplantation. Asx before, histological assessment of OLP animals showed: a) serotonergic axons were present in the cord below the transection site; b) brainstem raphe nuclei was retrogradely labeled; c) bisbenzimide pre-labeled cells from OLP transplants migrated in host spinal cord. These changes were not seen in control animals. These results indicate that OLP has the ability to promote axonal regeneration in chronically injured cord of adult rats. Chapter Seven compares the results from these three types of intervention. In conclusion, these studies show that peripherally derived OECs or solid pieces of OLP can promote partial spinal cord repair in acute or chronic transection injuries. Such tissue might provide a potential source for autologous grafting in human paraplegia.