Does dietary tocopherol level affect fatty acid metabolism in fish?

Fish are a rich source of the n-3 polyunsaturated fatty acids (PUFA), particularly the highly unsaturated fatty acids (HUFA), eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 22:6n-3) acids, which are vital constituents for cell membrane structure and function, but which are also highly susceptible to attack by oxygen and other organic radicals. Resultant damage to PUFA in membrane phospholipids can have serious consequences for cell membrane structure and function, with potential pathological effects on cells and tissues. Physiological antioxidant protection involves both endogenous components, such as free radical scavenging enzymes, and exogenous dietary micronutrients including tocopherols and tocotrienols, the vitamin E-type compounds, widely regarded as the primary lipid soluble antioxidants. The antioxidant activities of tocopherols are imparted by their ability to donate their phenolic hydrogen atoms to lipid (fatty acid) free radicals resulting in the stabilisation of the latter and the termination of the lipid peroxidation chain reaction. However, tocopherols can also prevent PUFA peroxidation by acting as quenchers of singlet oxygen. Recent studies on marine fish have shown correlations between dietary and tissue PUFA/tocopherol ratios and incidence of lipid peroxidation as indicated by the levels of TBARS and isoprostanes. These studies also showed that feeding diets containing oxidised oil significantly affected the activities of liver antioxidant defence enzymes and that dietary tocopherol partially attenuated these effects. However, there is evidence that dietary tocopherols can affect fatty acid metabolism in other ways. An increase in membrane PUFA was observed in rats deficient in vitamin E. This was suggested to be due to over production of PUFA arising from increased activity of the desaturation/elongation mechanisms responsible for the synthesis of PUFA. Consistent with this, increased desaturation of 18:3n-3 and 20:5n-3 in hepatocytes from salmon fed diets deficient in tocopherol and/or astaxanthin has been observed. Although the mechanism is unclear, tocopherols may influence biosynthesis of n-3PUFA through alteration of cellular oxidation potential or “peroxide tone”

Molecular biology of the blood-brain and the blood-cerebrospinal fluid barriers: similarities and differences

Efficient processing of information by the central nervous system (CNS) represents an important evolutionary advantage. Thus, homeostatic mechanisms have developed that provide appropriate circumstances for neuronal signaling, including a highly controlled and stable microenvironment. To provide such a milieu for neurons, extracellular fluids of the CNS are separated from the changeable environment of blood at three major interfaces: at the brain capillaries by the blood-brain barrier (BBB), which is localized at the level of the endothelial cells and separates brain interstitial fluid (ISF) from blood; at the epithelial layer of four choroid plexuses, the blood-cerebrospinal fluid (CSF) barrier (BCSFB), which separates CSF from the CP ISF, and at the arachnoid barrier. The two barriers that represent the largest interface between blood and brain extracellular fluids, the BBB and the BCSFB, prevent the free paracellular diffusion of polar molecules by complex morphological features, including tight junctions (TJs) that interconnect the endothelial and epithelial cells, respectively. The first part of this review focuses on the molecular biology of TJs and adherens junctions in the brain capillary endothelial cells and in the CP epithelial cells. However, normal function of the CNS depends on a constant supply of essential molecules, like glucose and amino acids from the blood, exchange of electrolytes between brain extracellular fluids and blood, as well as on efficient removal of metabolic waste products and excess neurotransmitters from the brain ISF. Therefore, a number of specific transport proteins are expressed in brain capillary endothelial cells and CP epithelial cells that provide transport of nutrients and ions into the CNS and removal of waste products and ions from the CSF. The second part of this review concentrates on the molecular biology of various solute carrier (SLC) transport proteins at those two barriers and underlines differences in their expression between the two barriers. Also, many blood-borne molecules and xenobiotics can diffuse into brain ISF and then into neuronal membranes due to their physicochemical properties. Entry of these compounds could be detrimental for neural transmission and signalling. Thus, BBB and BCSFB express transport proteins that actively restrict entry of lipophilic and amphipathic substances from blood and/or remove those molecules from the brain extracellular fluids. The third part of this review concentrates on the molecular biology of ATP-binding cassette (ABC)-transporters and those SLC transporters that are involved in efflux transport of xenobiotics, their expression at the BBB and BCSFB and differences in expression in the two major blood-brain interfaces. In addition, transport and diffusion of ions by the BBB and CP epithelium are involved in the formation of fluid, the ISF and CSF, respectively, so the last part of this review discusses molecular biology of ion transporters/exchangers and ion channels in the brain endothelial and CP epithelial cells

Escherichia coli O157 serotype in beef carcasses post slaughterhouse in Nairobi and Eldoret, Kenya

The research covered three slaughterhouses in Nairobi and Eldoret. The objectives were to assess the prevalence of E. coli O157 serotype contaminated carcasses at dispatch, the possible cross-contamination during transportation, and knowledge, attitude and handling practices that led to increased contamination or bacterial growth. Randomly selected 250 beef carcasses were sampled. Swab samples from a single carcass were obtained from three sites during loading and offloading of meat to carriers. A total of 1500 samples were obtained. E. coli O157 serotype was isolated, and purified using sorbital MacConkey, MacConkey and nutrient agar. Serotyping was by card agglutination test. Oxoid verotoxin test kit was used to test for verotoxin (VT1 and VT2) production. Carrier environment was monitored. Knowledge, attitude and practices of meat transporters were assessed through a semi structured questionnaire and observations. Probability of contamination was modeled and run through Monte Carlo simulation using winBUGS®. Prevalence and data from the questionnaire were analysed using SPSS Ver.17. The contamination prevalence at offloading was significantly higher compared to loading (p = 0.05). The probability of obtaining an E. coli O157 serotype contaminated carcass at Dagoretti, Limuru and Eldoret, respectively, was 14, 16 and 19 at loading and 31, 39 and 66 at offloading per 1000 carcasses handled. The temperature in the meat carrier significantly increased (p = 0.004) during transportation between loading and offloading. The average time taken to transport the meat from the slaughterhouses to the butchery was 65 minutes. About 14 (43.8 %) of the meat transporters had worked in the meat industry for at least 5 years and almost an equal number 13 (40.4%) had had formal training on meat hygiene. About 53% of meat transporters claimed to wash hands regularly with cold water and soap. Meat carriers were cleaned at the river or in a car wash with cold water and soap only. Carcasses were loaded on the shoulders of the transportation personnel and placed on the floor of the carriers or heaped on top of other carcasses. Offloading at the butchery was done by the same person with no change over of clothes that could be soiled with blood

Bacterial Wilt, A Challenge in Solanaceous Crops Production At Kenyan Highlands and Lowlands

Ralstonia solanacearum, the causal agent of bacterial wilt disease, results in serious world-wide economic losses particularly in the tropics. Members of the family Solanaceae such as potato, tomato, chili and tobacco are the most affected. A survey was conducted in the period of short rains (October December ) the year 2015, coveringnbsp Kenyan highlands and lowland regions of Nyeri, Kiambu, Nyahururu, Kirinyaga, Murangrsquoa, and Embu counties the major production zones of potato, tomato and capsicum to determine the prevalence, effects and management measures in practice by farmers in control of this bacterium. The findings implicated high dependence of farmers to the solanaceous crops both for income and food (68%), and extensive presence of the bacteria in all the seven study counties. The survey indicated bacterial wilt as a big challenge in production of Solanaceae crops in central Kenya. Lack of elaborate disease management measures and poor seed systems (57%) were found to be the key contributors to the extensive spread, high prevalence (68.57%) and the high incidence (17.74%) of the disease. These findings indicated an urgent need for set up of affordable up to standards seed systems of Solanaceae crops family. This output will enable experimentation of the plant extracts and organic supplements as cheap measures in management of the bacterium leading to alleviation of bacterial wilt challenges in Kenyan highlands and lowlands