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Fish provides a major source of proteins and polyunsaturated fatty acids which are known to prevent coronary heart diseases. However, inherent characteristics such as colour and texture prevent the effective utilisation of some fish, especially fatty pelagics for human consumption. Instead, they are used for fish oil and fish meal production. For this reason and for enhancing the utilisation of valuable resources, the physico-chemical properties, which may be species specific, were investigated in relation to two Namibian species, namely, horse mackerel (Trachurus capensis) and snoek (Thyrsites atun). The results showed that horse mackerel (Trachurus capensis) and snoek (Thyrsites atun) contain high contents of palmitic acids (29%), oleic acids (25%), and the omega-3-polyunsaturated fatty acids, such as docosahexaenoic acids (DHA) (15%) and eicosapentaenoic acids (EPA) (9%). The studies also showed that optimum protein extractability was obtained with 5% NaCl at pH 7.2 and the highest gel strength at pH 6.5-7.0. CaCO3 had detrimental effect on the water-holding capacity when used above 50mg.l-1 in washing water. Agar and sodium alginate extracted from Namibian Gracilaria verrucosa (red seaweed) and Laminaria schinzii (brown seaweed) respectively, were also characterised for their physico-chemical properties. Both the nontreated and treated agars were observed by colorimetric method to contain low levels of sulphate, an observation also confirmed by NMR and Raman FTIR spectroscopy. Sodium alginate was found to contain high content of guluronic acid (75%) by NMR, a good index of strong gelling ability. The good functionalities obtained as a result of optimising the physicochemical properties of fish proteins and seaweed polysaccharides enabled an investigation of the interactions of the two components. Studies on the interactions of the both horse mackerel and snoek with either sodium alginate or agar were undertaken by rheology, differential scanning calorimetry and phase contrast microscopy. Large deformation and small deformation rheological studies showed a decrease in the gel strength of fish proteins with the addition of either polysaccharide at all combinations. The DSC results indicated a lowering of the denaturation temperature with the addition ratios of increasing amounts of sodium alginate to fish proteins. Although the mixture of fish proteins and agar resulted in the lowering of the denaturation temperature, the shift; was not as pronounced as that obtained with sodium alginate. The reason for the lowering of gel strength and G' values was attributed to phase separation of fish proteins and polysaccharides which was reflected by phase contrast microscopy studies. This investigation has resulted in the characterisation of valuable fish and seaweed polysaccharide resources from Namibia which could be used in combination for the development of new food products.

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This study was developed from the original protocol which was to examine the role of long chain polyunsaturated fatty acids (LCPUFA) in the maturation of the auditory system in the preterm infant. The particular dietary components under investigation were arachidonic (AA) and docosahexaneoic( DHA) acids. This study investigates the wider aspects and implications of the preterm birth on the maturation of the preterm auditory system. Testing was performed using Auditory brainstem response (ABR) on preterm infants in Hillingdon Hospital's neonatal intensive care unit (NICU). The recruitment criteria was <32 weeks gestational age (GA) or <1500g. A normative data set was produced using term infants (3742 weeks GA). Tympanometric testing was also introduced to assess middle ear (ME) function in both preterm and term infants. The susceptance and conductance components were recorded at frequencies between 226 and 2000Hz. This testing enabled normative data to be established for multi-component, multi-frequency tympanometric analysis. The effect of the preterm birth on tympanometric data was also examined. A total of 22 preterm infants were recruited onto the study. The maturational characteristics of ABR parameters relating to neural transmission and synaptic efficacy were investigated. The peripheral auditory system (PAS) and the lower brainstem region were found to have maturation in their neural transmission properties. The auditory nerve, however, displays constant neural transmission properties throughout the preterm period. Maturation of the synaptic efficacy (using the rate effect) of the PAS was not identified. However, both auditory nerve and lower brainstem regions display reductions in the rate effect. This was greatest in the auditory nerve. The effect of the preterm birth was assessed. The PAS showed lesser conductive properties for the preterm infant during the term period. This behaviour was confirmed by poor tympanometric data for the preterm infants. The auditory nerve showed the same transmission properties for both term and preterm infants. This indicates that the lack of maturation in this region is replicating the characteristics of the term infant developing in utero. The lower brainstem region would seem to be the most susceptible to delayed development in the preterm infant. The rate effect for the PAS and auditory nerve indicate that the extra-uterine environment has not been detrimental to the maturation of synaptic efficacy as measured by the rate effect. The lower brainstem region rate effect is slightly higher for the preterm infants. This may indicate that this region is the most susceptible to possible synaptic deficiency. There is indication of a gender effect for transmission properties in the preterm infant. This suggests superior properties for females in the central auditory system. It is possible that this also occurs on a synaptic level. Dietary analysis suggested that the preterm infants (on this study) fed formula milk enriched with a LCPUFA composition have comparable auditory function (as measured by ABR) with breastfed infants. It is concluded that breastmilk would be the diet of choice due to the additional medical benefits. Tympanometry was found to be well tolerated in both term and preterm neonate populations. Testing in enclosed style incubators in the NICU was successful. Normative characteristics for multi-component tympanornetry at various frequencies was established. The ear canal acoustic and mechanical properties were identified as a source of variability for tympanogram morphology in the neonate populations. The interaction of the neonate external auditory meatus (EAM) violates assumptions relating to numerical data. A lack of maturation was found for preteen data, there was no evolution to the normative term data over the period studied. The more complex nature of the preterm tympanometric data was still observed during the term period. This indicates that there is a difference between the maturational characteristics of the term infant and those for the preterm infant in the clinical environment. The PAS ABR characteristics were compared with tympanometric data collected from the preterm infants. The lack of maturation in the tympanometric data suggests that the major contribution to the ABR maturation during the preterm period is due to the cochlear transduction and basic synaptic delay components. In addition, that poorer ME function (as displayed in the tympanometric data) contributes to the lesser PAS ABR conductive properties in the preterm population by the term period.

Basic and clinical research documents the benefits of dietary milled flaxseed (MFX), a rich source of alpha-linolenic acid (ALA) and lignans, in the attenuation of risk factors key to regulating cardiovascular disease (CVD) progression. ALA has antihypertensive properties and the lignan metabolites, enterodiol (END) and enterolactone (ENL), have antioxidative potential. The effectiveness of these bioactives to reduce risk factors of CVD may be dependent upon their plasma concentrations. To study this, we first designed and validated a method using supported liquid extraction and gas chromatography/mass spectrometry to isolate and quantify enterolignans in plasma. Applying this technique, we examined MFX doses of 10-40 g/d administered to healthy, younger adults (18-49 years of age) for 4 weeks. Ten g/d was sufficient to significantly increase circulating ALA (1.5 fold) and enterolignans (5-31 fold). There was no significant dose-dependent response. In another investigation, younger (18-29 years of age) and older (45-69 years of age) healthy adults were studied to determine if age influenced enterolignan metabolism. CVD is associated with advanced age but older people may not be able to obtain lignan metabolites from dietary MFX. Following 4 weeks of MFX consumption, both age groups increased plasma total enterolignans (END + ENL) with no between-group differences. This suggested that older and younger adults metabolize MFX lignans equally. A final study assessed MFX bioactives in plasma of peripheral artery disease patients >40 years of age. Plasma enterolignans increased 10-50 fold and ALA 1-2 fold after only one month of MFX ingestion. Dietary MFX also attenuated total (11%) and LDL (15%) cholesterol in these patients after 1-6 months of administered MFX compared to placebo. The attenuation in cholesterol was due to the high fiber content of flaxseed, and not to ALA and enterolignans, despite their marked increase in circulation. MFX did not interfere with cholesterol-lowering medications but instead decreased cholesterol levels beyond the effects of medications alone. To conclude, dietary supplementation with MFX resulted in an increase in plasma enterolignan and ALA concentrations in healthy younger and older adults and in patients with pre-existing CVD. The cholesterol-lowering benefits of MFX were additional to cholesterol-lowering drugs and likely attributed to MFX fiber. / May 2016

To examine how dietary n-3 polyunsaturated fatty acids affect Th2 cell development, female C57BL/6 mice were fed a washout corn oil (CO) diet for 1 wk followed by 2 wk of either the same CO diet or a fish oil (FO) diet. CD4+ T cells were isolated from spleens and cultured under both neutral (anti-CD3 and phorbol myristate acetate (PMA)) and Th2 polarizing conditions (anti-CD3 and PMA, in presence of rIL-4, rIL-2, and anti-IFN-γ) in the presence of homologous mouse serum (HMS) or fetal bovine serum (FBS) for 2 d. Dietary n-3 PUFA significantly enhanced Th2 cell development and suppressed Th1 development under neutral conditions as assessed by intracellular cytokine staining for IL-4 and IFN-γ as the two prototypic Th2 and Th1 cytokines, respectively. However, under Th2 polarizing conditions, while the suppression of Th1 cells was maintained in FO-fed mice, no dietary effect was observed in Th2 cells. Dietary FO increased the Th2/Th1 ratio under both neutral and Th2 polarizing conditions with HMS in the cultures. To examine the effect of dietary n-3 PUFA on Th1 development, DO11.10 Rag2-/- mice expressing transgenic T cell receptor specific for ovalbumin (OVA) peptide were used. CD4+ T cells were isolated from spleens and lymph nodes and stimulated with ovalbumin (OVA) peptide and irradiated BALB/c splenocytes in the presence of rIL-12, anti-IL-4, and rIL-2 in HMS for 2d. Cells were expanded for another 3 d in the presence of rIL-2 and rIL-12. Dietary n-3 PUFA did not affect Th1 differentiation as assessed by the proportion of IFN-γ+, IL-4- T cells in the cultures, but suppressed rIL-2 induced expansion. The suppressed expansion was due to suppressed proliferation (p<0.05). In vivo expansion of antigen-specific T cells was visualized by flow cytometric analysis of CFSE-positive transgenic T cells. Dietary n-3 PUFA did not appear to affect antigen-induced CD4+ T cell cycle progression in vivo. Overall, these results suggest dietary n-3 PUFA have no direct effect on Th2 cell development but do directly suppress Th1 cell development following both mitogenic and antigenic stimulation in vitro.

Polyunsaturated fatty acids (PUFA) affect key cellular and physiological processes in the body ranging from cell signalling to inflammation. Compositional, dietary refinement and bioassay studies have shown strong associations between the PUFA composition of skeletal muscle with various contractile properties as well as the development of obesity and insulin resistance. The incorporation of PUFAs into rat soleus (slow-twitch oxidative), red gastrocnemius (fast-twitch oxidative), and white gastrocnemius (fast-twitch glycolytic) muscle were examined using stable isotope-labelled fatty acids. Two separate tracer studies were conducted. In the first study, four groups of rats were orally dosed with one of three isotopes of 18:2n-6; 13C18-18:2n-6 ethyl ester, 13C18- 18:2n-6 nonesterified fatty acid or 2H5-18:2n-6 ethyl ester and a control group received the vehicle only (olive oil). Animals were sacrificed 8 hours post dosing and soleus, red and white gastrocnemius muscles were collected for lipid analysis. In the second study, rats were orally administered a single dose of a mixture of 4 isotopes (13C18-18:2n-6, 2H5-18:3n-3, 13C16-16:0, and 2H2-18:1n-9) or vehicle only (olive oil) as a control. Groups of animals were sacrificed at 8, 24, and 48 h after dosing and four muscle types (heart, soleus, red and white gastrocnemius) were collected and analyzed for isotopic signal of these fatty acids and their corresponding desaturation and/or elongation products. Soleus accumulated significantly higher concentrations of labelled 18:2n-6, 18:3n-3 and most of n-6 fatty acids derived from 18:2n-6 followed by red gastrocnemius and white gastrocnemius. Heart muscle accumulated 20:5n-3 and 22:6n-3 increasingly over time while skeletal muscle accumulation was variable across muscle types. Labelled 20:5n-3 was detected in red and white gastrocnemius at 8 and 24 h with levels declining by 48 h while no 20:5n-3 was detected in soleus at anytime. Labelled 22:6n-3 was not detected in white gastrocnemius, but 22:6n-3 appeared to be increasing in red gastrocnemius over time. Soleus demonstrated a large accumulation of 22:6n-3 at 8 h with no detectable levels at 48 h. In conclusion we were able to demonstrate that the distribution and metabolism of various PUFAs differ in muscle types with distinct fibre type composition.

Polyunsaturated fatty acids (PUFA) affect key cellular and physiological processes in the body ranging from cell signalling to inflammation. Compositional, dietary refinement and bioassay studies have shown strong associations between the PUFA composition of skeletal muscle with various contractile properties as well as the development of obesity and insulin resistance. The incorporation of PUFAs into rat soleus (slow-twitch oxidative), red gastrocnemius (fast-twitch oxidative), and white gastrocnemius (fast-twitch glycolytic) muscle were examined using stable isotope-labelled fatty acids. Two separate tracer studies were conducted. In the first study, four groups of rats were orally dosed with one of three isotopes of 18:2n-6; 13C18-18:2n-6 ethyl ester, 13C18- 18:2n-6 nonesterified fatty acid or 2H5-18:2n-6 ethyl ester and a control group received the vehicle only (olive oil). Animals were sacrificed 8 hours post dosing and soleus, red and white gastrocnemius muscles were collected for lipid analysis. In the second study, rats were orally administered a single dose of a mixture of 4 isotopes (13C18-18:2n-6, 2H5-18:3n-3, 13C16-16:0, and 2H2-18:1n-9) or vehicle only (olive oil) as a control. Groups of animals were sacrificed at 8, 24, and 48 h after dosing and four muscle types (heart, soleus, red and white gastrocnemius) were collected and analyzed for isotopic signal of these fatty acids and their corresponding desaturation and/or elongation products. Soleus accumulated significantly higher concentrations of labelled 18:2n-6, 18:3n-3 and most of n-6 fatty acids derived from 18:2n-6 followed by red gastrocnemius and white gastrocnemius. Heart muscle accumulated 20:5n-3 and 22:6n-3 increasingly over time while skeletal muscle accumulation was variable across muscle types. Labelled 20:5n-3 was detected in red and white gastrocnemius at 8 and 24 h with levels declining by 48 h while no 20:5n-3 was detected in soleus at anytime. Labelled 22:6n-3 was not detected in white gastrocnemius, but 22:6n-3 appeared to be increasing in red gastrocnemius over time. Soleus demonstrated a large accumulation of 22:6n-3 at 8 h with no detectable levels at 48 h. In conclusion we were able to demonstrate that the distribution and metabolism of various PUFAs differ in muscle types with distinct fibre type composition.