Supplementing dams with both arachidonic and docosahexaenoic acid has beneficial effects on growth and immune development.

Omega-3 long-chain polyunsaturated fatty acids (LCPUFAS) modulate immune cells in vitro and in vivo. This study investigated the effects of enriching the maternal diet with the n-6 and n-3 LCPUFAs, arachidonic (20:4n-6, 0.6%wt ARA) and docosahexaenoic acid (22:6n-3, 0.32%wt DHA), or 1:1 and 2:1 ratios (ARA: DHA) on total lipids in milk, total lipids, and immunophenotypes in plasma, lymph nodes, and spleen from isolated immune cells from 28d old pups. From day 15 of gestation to day 3 pp, Sprague-Dawley dams were fed a commercial chow. On day 3 pp litters were culled and pups (4 males and 2 females) randomly cross-fostered to dams who were randomized to one of the 5 experimental diets resulting in 20 male and 10 female pups/diet group. Dams fed ARA or ARA: DHA had 28-36% more 20:4n-6 in milk and feeding DHA or ARA: DHA doubled 22:6n-3 in milk lipids (P<0.05). Feeding 1:1 or 2:1 ARA: DHA resulted in greater pup weight at weaning (P<0.05). Compared to the control pups, ARA + DHA fed pups had a lower proportion of splenic CD45RA+ lymphocytes. In summary, postpartum supplementation with a combination of ARA + DHA, compared to ARA or DHA alone, resulted in a higher content of ARA and DHA in dam's milk and tissues and had positive effects on growth, accompanied by evidence of progression toward a mature immune phenotype, and suggests a need for ARA when DHA is supplemented in the early diet. Additional investigations are needed of ARA immunomodulation to better understand and estimate nutritional requirements for LCPUFAs during early development.

The oil-rich alga Schizochytrium sp. as a dietary source of docosahexaenoic acid improves shape discrimination learning associated with visual processing in a canine model of senescence.

Whole cell Schizochytrium sp. is a rich source of omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) including docosahexaenoic acid (DHA), an important nutrient for brain health. Aged beagle dogs experienced on a visuospatial task of working memory, variable-delay delayed-non-matching-to-position were used to assess efficacy of DHA-rich microalgae based upon DHA wt% of total phospholipids and 8-iso-PGF2α concentrations in plasma, and performance on cognitive assessments of visual object discrimination, learning, and memory consolidation after 25 weeks on fortified diet. Improved DHA status (p<0.001) and initial learning of the protocols for visual and variable contrast discrimination (p<0.05), but not long-term recall of the concurrent discrimination task were observed in animals fed the algal-fortified diet. Overall, results were consistent with dried Schizochytrium sp. as a source of n-3 LCPUFA nutrition to support DHA status in large mammals, and healthy brain function in a canine model of senescence.

Preclinical safety evaluation in rats using a highly purified ethyl ester of algal-docosahexaenoic acid.

Preclinical studies have shown that docosahexaenoic acid (DHA) derived from microalgae (DHASCO) is neither mutagenic nor toxic in acute, subchronic or developmental tests. DHASCO, triglyceride oil from the fermentation of Crypthecodinium cohnii, contains 40-50% (400-500 mg/g) of DHA by weight. Martek Biosciences Corporation has developed a concentrated ethyl ester of DHA (900 mg/g) from DHASCO (MATK-90). A 90-day subchronic safety study with a one-month recovery period using Sprague-Dawley rats included clinical observations, ophthalmic examination, hematology, clinical chemistry, toxicokinetic evaluation, and pathological assessments. Effects of MATK-90 were compared with those produced from DHASCO and control (corn oil). Doses of MATK-90 (1.3, 2.5 and 5.0 g/kg/day) and DHASCO (5.0 g/kg/day=2g of DHA) were administered once-daily by oral gavage at a volume of 10 mL/kg. The corn oil was also administered by oral gavage (10 mL/kg/day). There were no treatment-related adverse effects in any of the parameters measured at doses of

Catalytic activity of administered gulonolactone oxidase polyethylene glycol conjugates.

Scurvy in guinea pigs provides a convenient model of inborn metabolic disease for the investigation of enzyme therapy protocols. Gulonolactone oxidase, the enzyme in ascorbic acid biosynthesis that is missing from the scurvy-prone species, was modified by attachment of polyethylene glycol. The catalytic properties of this enzyme were affected little by the modification. Intravenous injection of this modified form of the enzyme elicited ascorbic acid synthesis in a dose-dependent manner. The modified enzyme was stabilized to incubation at 37 degrees C but was not protected from inactivation by trypsin. The circulating half-life of enzyme activity was not prolonged by this modification. Further, attachment of polyethylene glycol did neither abolish the enzyme's ability to react with preformed antibodies nor eliminate its immunogenicity.

Heterologous immunoprecipitates also have potential for therapeutic use.

Potential therapeutic usefulness of administered enzymes is limited by toxicity and allergenicity. To overcome these problems we are using scurvy to test various enzyme modifications that may be suitable for therapy. L-Gulonolactone oxidase, which catalyzes the final step in ascorbic acid biosynthesis, is immunoprecipitated with specific antisera from rabbits and then cross-linked with glutaraldehyde. The modified enzyme retains activity sufficient to elicit ascorbic acid synthesis in scorbutic guinea pigs. Intraperitoneal injection of this altered enzyme to animals supplemented with L-gulonolactone increases plasma concentrations of the vitamin. Importantly, multiple doses of the complex are tolerated. Therefore, it is possible to prolong survival time of animals fed an ascorbic acid-deficient diet by this enzyme replacement therapy. This procedure can also be applied to other enzymes that have potential therapeutic use. Serum cholinesterase and asparaginase both retain activity after this modification and are tolerated in single or in weekly repeated injections. Following three or four weekly injections, an anaphylactic reaction to serum but not to enzyme can be elicited if they are injected intravascularly. We conclude that the stability of the immobilized foreign enzyme is a critical factor in lessening the toxicity to multiple injections of these foreign proteins.

Monocrotaline pyrrole-induced cardiopulmonary toxicity is not altered by metergoline or ketanserin.

Monocrotaline pyrrole (MCTP) causes endothelial cell damage, pulmonary hypertension and right ventricular hypertrophy in rats by an undetermined mechanism. A role for 5-hydroxytryptamine (5-HT) in the cardiopulmonary response to MCTP has been suggested. To investigate the role of 5-HT, the effects of two 5-HT receptor antagonists were examined in MCTP-treated rats. Cotreatment with metergoline, an antagonist which binds to both 5-HT1 and 5-HT2 receptors, did not alter MCTP-induced elevation of lung weight or right ventricular hypertrophy. 5-HT-induced vascular smooth muscle contractions are mediated by 5-HT2 receptors; therefore, MCTP-treated rats were cotreated with ketanserin (KET), a specific 5-HT2 receptor antagonist. At a dosing regimen of KET that inhibited the 5-HT-induced platelet shape change in platelet-rich plasma and the 5-HT-induced increase in perfusion pressure in isolated lungs, KET did not affect the elevation in lung weight or the increased accumulation of 125I-albumin in the lung tissue of MCTP-treated rats. Moreover, MCTP-induced right ventricular hypertrophy was not attenuated by KET. These results indicate that cotreatment with either of these two 5-HT receptor antagonists does not alter the lung injury or right ventricular hypertrophic response to MCTP and suggest that 5-HT is not necessary for MCTP-induced toxicity.