Top PDF Abomasal secretion in parasitised sheep : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physiology at Massey University

antigenic determinants. As worms present large, non-phagocytosable surfaces to the host's defences they are most vulnerable to cells capable of mediating ex trace llular events. Nematode infections are characterised by high 19E responses, eosinophilia and mastocytosis and the interaction of these (Armour et aI., 1966; Smith et aI., 1986; Wakelin, 1992; Miller, 1993; Pritchard, 1993). The eosinophil/lgF/mast cell axis is thus of particular importance in defense against these parasites (Butterworth, 1984). IgA is the dominant immunoglobulin in gastrointestinal secretions (Wakelin, 1978). A host that is producing 19E in response to O. circumcincta antigens may be considered sensitized or allergic to the parasite. In immune sheep, there are large numbers of mast cells and globule leucocytes in the gastric mucosa (Smith, 1988). Contact between Ostenagia and mast cells sensitized with specific 19E that was produced in response to current or previous infections leads to degranulation of the mast cell and the release of many infl amm atory mediators (Kay, 1985). Some .comment as to the nature and actions of such substances has been made (Section 1 .4). Mast cells could also interact with larvae coated with complement (Sher & Glover, 1976) which may non-specifically induce their degranulation (Nawa, 1979). This may be of particular importance in primary infections prior to the production of specific 19E and other antibodies. On reinfection of immune sheep, there is an increase in mast cell protease in the lymph, demonstrating that mast cell degranulation has occurred (Smith, 1988). Simultaneous release of histamine and other components would affect mucosal permeability and afford a temporary increase in plasma pepsinogen (Yakoob et aI., 1983).

A thesis presented in partial fulfilment of the requirements for the degree of Doctor .of Philosophy at Massey University... by the dominant class , the..[r]

changes were prominent features . Alternat ively , i t could somet imes be found well developed in lungs where there was only minimal proliferat ive change and could even be found in occasional lungs from normal lambs collected during the latter half of the pneumonia season. The histolog­ ical di vision of pneumonic lungs into lymphoid and interst itial types as was att empted by Stamp and Nisbet ( 1 963) did not seem warranted in the presen t study as there was considerable overlap of lesions of this type in many of the pneumonias . Instead an attempt was made t o divide the lungs into 4 groups according to their gross lesions and the degree of exudat ive and proli ferat ive changes which were present microscopically. Although no definit ive boundaries could be drawn between the lesions in the 4 different groups the excerc ise was considered useful as it high­ lighted what is probably the natural progression of the disease from early ( type 1 ) through to advanced ( type 4) lesions . It should be noted however , that this suggest ion does not encompass the not ion that a progression of this kind is inevitable once t ype 1 lesions occur . On the c ontrary , the recovery of lungs following type 1 lesions without undergoing severe de�truct ive and proliferat ive c hanges remains a real possib il ity which requires further invest igat ion.

motility and abomasal acid secretion . Othe r effects o f the intraduodenal adminis trati on of fat and ot her subs tan ces have been studied and reported . Hill ( 1965 ) describe d changes in acidity o f ab omasal secretion and the flow of di gesta from the abomasum resul ting from the addi tion o f triglyceride to the diet . Singleton ( 1951 ) infus e d carbohydra te , protein and fat into the duodenum and repor ted e ffec ts on aboma sal motility . Phillips ( 1965 ) r eported exper iments in which the infusion of C1 8 unsatura ted fatty acids into the duodenum caused diarrhoea and inappetenc e . Tit chen , Reid and Vlieg ( 1 966 ) inv estigated the effec ts of int raduodenal infusions of fat on the food intake of she ep . Mov ements of the re ticulum and rumen were recorded from part ial exteriorizations of the se regions .

The concentration of G RP necessary to stimulate gastrin release in the present experiments was greatly in excess of concentrations required for other species. Porcine antral gastrin secretion was doubled by 1 0-1 1 M GRP (Hoist et al., 1 987a) , with similar results for tissue from rats and humans (Richelson et al. , 1 983) . Sequence differences between ovine and human or porcine G RP may result in poorer binding of the latter two for the ovine G RP receptor. Fraser et al. ( 1 994) reported that ovine G RP has an identical C-terminal decapeptide sequence to human and porcine forms, but has differences in the N-terminal sequence. Whether or not differences in the N-term inal are important for G RP receptor binding is unknown , but N-terminal differences do define differing receptor specificity for gastrin and cholecystokinin. Bombesin receptor subtype 3 (BRS-3) has been characterised in sheep (Whitley et al. , 1 999) and shown to be different from BRS-3 in humans (Gorbu lev e t al., 1 994) , mice and guinea pigs (Akeson et al., 1 997) at one amino acid site which is critical for agonist binding. BRS-3 has affinity for bombesin in the m icromolar range, while other members of the G RP receptor family have affinity in the nanomolar range (Akeson et al. , 1 997) . Although BRS-3 may not be the receptor expressed in the sheep antrum causing the observed low affinity for G RP, the difference between sheep BRS-3 and BRS-3 in other species at a site critical for peptide binding illustrates that sheep G R P receptors may differ from those in other species, with different binding properties.

An extensive vo lume of literature i s available on lymphosar coma of cattle in whi ch spe cie s an enzootic form of possible viral aetiology i s present (Bendexin, 1 965 ; Dut cher , Larkin , Tumilowi cz , Nazarian, Eusebio, Stock, Guest and Marshak, 1 967 ) . Similarly, t here are indications of a t ransmissible aetiological agent in feline lympho­ sarcoma ( S chneider, Frye , Taylor and lJorn, 1 967 ; Thei len, 1 968 ) . Despite thi s , and the relatively cormnon occurrence 0f lymphosarcoma in sheep , no experimental work and fei·l epidemiological obse rvations

Ang l icans continued to fo l l ow British d e v e l opments c l os e l y. The Church Gazette , for instance , reported eminent Br itish sci entist Dr Carpenter 's 1 87 3 assertion that evo lution presented 'a far grand e r notion o f Creat i v e Des ign , than the idea of specia l interpositions required to remed y the irregu l ar working o f a machine irregu l ar l y constructed in the first instance1•22 High Churchman Canon H.P. Liddon was reported in the same year as asserting that e v o l ut ion ' from a Theistic point o f v iew, i s mer e l y our way o f describing what we c an observe of God ' s cont inuous action upon the physical wor l d 1 •23 By the end of the decade Canon Curteis articu l ated the Br itish trend whi ch co loni a l Ang l i cans undoubted l y fo l l owed : 'To a l arge and increasing number of Churchmen the e v o l ution hypothes i s appears , not on l y

Observations have also been made of the intravenous infusion of various substances reported to influence gastric secretion. Extracts exhibiting 'enterogastrone' activity have been tested; the effects of insulin studied; and the action of a synthetic gastrin ( ICI 50 , 123) which exhibits gastrin-like properties has been i n ves t i g at e d.

interdigital dermatitis and this is supported by their subsequent observations Roberts et a£., 1968 that both conditions were present in flocks at the same time and that in several insta[r]

1 9 6 5 ) . Whi le some s h r i nkage of nerve f i bres ha s been observed at the u l t r a s tructural leve l , a s a resul t of f i x a t i on and subsequent proce s s ing of nerve , i t ha s been conc luded that no appre c iable change in morphology occur s , a s a l l components of nerve f i bres are a f fected to a s im i lar degree ( Arbuthnot t e t a � 1 9 8 0 ) . The preservat ion of nerve f i bres in e l ectron m i cros copy is cons idered to be adequa te if no s pl i t t ing of the mye l i n s heath has occurred , apart f rom the Schmidt-Lantermann i n c i sure s , if the axo lemma adhere s c l o s e ly to the i nner turns of the mye l i n sheath , and i f the f i ne structure of mitochondria , neurof i l aments and mi crotubu l e s is pre served . Some spl i t t i ng of the mye l i n i s l ikely i n the large s t f ibres w i th the thick e s t mye l i n shea th s ( Arbuthnott e t aL , 1 9 8 0 ) . Unmy? l i na ted nerve f i bre s may be v i s ible on l i ght mi croscopy , but can on ly be examined in deta i l by e lectron m i croscopy . Observat ion of the f i ne s tructure of axona l organe l le s may prov ide informa t ion l i nk i ng s t ructural changes of the various s ubce l lu l a r components w i th unde r l y i ng bi ochemi ca l d i s turbance s , a s we l l a s provid ing an extreme ly sen s i t ive method of detect ing minima l patho log i c a l change ( Dayan , 1 9 7 9 ) . Aga in , care mu s t be taken not to m i s take damage induced by inadequate care in the co l l ect i on a nd proc e s s ing of t he nerve , for true pa t holog i ca l change s .

Nematode carbohydrates are strongly antigenic and recognised by the host immune system (Harrison et al., 2003; Maass et al., 2007). C-type lectins (calcium- dependent carbohydrate-binding lectins), which are specific carbohydrate recognition receptors in dendritic cells and macrophages, play key roles in initiating and controlling innate and adaptive immune system (Janeway and Medzhitov, 2002). Human C-type lectin, a macrophage galactose (Gal)-type lectin, can specifically recognise α/β-GalNAc present on tumour cells and helminth parasites (van Vliet et al., 2005). Intelectins (Gal-binding lectins), mucus-associated proteins which are abundantly expressed in mice infected with Trichinella spiralis (Pemberton et al., 2004) or Trichuris muris (Datta et al., 2005) and in sheep challenged with T. circumcincta (French et al., 2008), are suggested to be involved in parasite rejection. In sheep, another lectin, ovine galectin-11 (or galectin-15) was also found in large amounts after infection (Dunphy et al., 2000). In humans, intelectin can recognise bacterial cell walls by the presence of galactofuranosyl residues which are not present in mammals. This recognition facilitates the induction of host protective immune responses resulting in the elimination of pathogens (Tsuji et al., 2001). Although further studies are required to elucidate their functions, these lectins are suggested to play important role in changing the properties and activities of mucus (French et al., 2008).

This project is by far the most significant accomplishment in my life. Various people deserve my sincere thanks for their immeasurable help to me throughout the course of this thesis. I must offer my profoundest gratitude to my thesis advisor and director of study, Dr Rabih Bashroush. He has inspired me to become an independent researcher and helped me realise the power of critical reasoning. He also demonstrated what a brilliant and hard-working scientist can accomplish. His unreserved help and guidance has led me to finish my thesis step by step. His words can always inspire me and bring me to a higher level of thinking. What I learnt from him is not just how to write a thesis to meet the graduation requirement, but how to view this world from a new perspective. Without his kind and patient instruction, it was impossible for me to finish this thesis.

A thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science Animal Science Department Massey University,... TABLE OF CONTENTS.[r]

A thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University.. KENNETH HAMI LT ON..[r]

This thesis examined the bacterial biotransformation of glucosinolates by two lactic acid bacteria and Escherichia coli Nissle 1917, all three considered beneficial bacteria. They were compared with a known glucosinolate-metabolising gut bacterium Enterobacter cloacae in vitro, in vivo and ex vivo to determine the bacterial responses to glucosinolates and what the products of their glucosinolate metabolism might be. Exposure of the host to beneficial bacteria and glucosinolates resulted in induction of the host detoxification enzyme quinone reductase which was elevated in bladder tissue for all dietary intervention groups consuming glucosinolates and beneficial bacteria, alone or combined.

from an initia l cro s s between Southdcwn and Hampsh ire Down sheep . Af fected sheep show loss of vi s ion and behav iou ra l abnorma l i t i e s starting at 11 - 1 2 month s o f age , with motor dysfunc tion commenc ing soon a fterwards. The c l i n i c a l s igns inc r e a s e in sever ity a s the d i se a s e progre s s e s and under field conditions a f fected anima l s are not expected to l ive beyond 2

The t re atment s were 4 diet s , l abe l led 1 through t o 4 , cont a ining guan idinated ge l at in ( GG ) and a b a s e in the rat i o s o f 0 . 5 : 1 , 1 : 1 , 1 . 5 : 1 and 2 : 1 respect i ve l y . The base was the s ame a s that used in exper iment 3 and c ompr i sed a cel l u l o s e to c o rnstarch mixture in the rat i o o f 3 : 1 . Bi rds were fed 2 0 g ( ai r dry ) o f e ach diet mixed with water in the rat i o of 1 g diet to 5 cc of water . The wate r was added immediat e l y p r i o r to feeding us ing cal ibrated 3 5 ml di spo s ab l e syringes . The t reatments were a l l o c ated randomly ove r the 3 2 b i rds to give 4 treatment each o f 8 bi rds . Intubat i on equ ipment and procedures were tho s e out l ined in exper iment 3 . I ntubat ion was comp leted within 2 hours and birds were s a c r i f i ced s ome 3 to 7 hour s fol lowing intubat i on on the b a s i s of degree o f crop empt ine s s and on the appearance of Cr in the droppings . The b i rds were sacr i fi c e d and digest a s amp l e s obt a ined u s ing the s ame procedures a s those de s c r ibed in experiment 3 . D ige s t a s amp l e s were col lected in sma l l p l a s t ic b a g s and s t o red overnight in a free zer before they were tran s ferred to the fre e z e dryer .

SHIRLEY BAKER AND THE KINGDOM OF TONGA by Noel Rutherford A thesis presented in partial fulfilment of the requirements of the Degree of Doctor of Philosophy in the Australian National University April[.]

A thesis presented in partial fulfilment of the requirement for the Degree of Doctor of Philosophy in Seed Technology at Massey University... MATERIALS AND METHODS..[r]

A THESIS PRESENTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHILOSOPHY IN VIROLOGY AND IMMUNOLOGY AT MASSEY UNIVERSITY.. OF THE PHILIPPINES.[r]