SummaryWe demonstrate here that CD59, an inhibitor of the membrane attack complex (MAC) of the complement system, is present in cell-free seminal plasma (SP) at a concentration of at least 20 #g/ml. Analyses by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and Edman degradation indicated that this protein, SP CD59, was similar, if not identical, to CD59 isolated from erythrocyte (E) membranes (E CD59). Like purified E CD59, SP CD59 also possesses a glycosyl phosphatidyl inositol (GPI) anchor and incorporates into the membranes of heterologous cells where it inhibits lysis by the human MAC. This phenomenon could be demonstrated not only if cells were incubated with purified SP CD59 but also if unfractionated SP were used. Further, CD59 in unfractionated SP bound to washed spermatozoa, increasing their membrane content of the protein. The mechanism by which this protein retains its GPI anchor while apparently present in the fluid phase is of interest and was further investigated. Using the techniques of high-speed centrifugation, fast performance liquid chromatography fractionation, and electron microscopy, we found that all detectable SP CD59 was associated with vesicular extracellular organelles. These organelles, named "prostasomes" were previously known to be present in SP and to interact with spermatozoa, although their function was uncertain. Interaction of heterologous E with prostasomes rendered the cells more resistant to lysis by human MACs. We propose that these organelles represent a pool of CD59 from which protein lost from spermatozoa, perhaps as a result of low level complement attack or of normal membrane turnover, can be replenished.

SDA-enriched soybean oil increased the omega-3 index by raising erythrocyte EPA concentrations. SDA-enriched soybean oil is a land-based n-3 fatty acid that is a sustainable approach to increasing tissue concentrations of long-chain polyunsaturated n-3 fatty acids.

ObjectiveLow-carbohydrate diets may be useful for weight loss. Diets high in vegetable proteins and oils may reduce the risk of coronary heart disease. The main objective was to determine the longer term effect of a diet that was both low-carbohydrate and plant-based on weight loss and low-density lipoprotein cholesterol (LDL-C).Design, setting, participantsA parallel design study of 39 overweight hyperlipidaemic men and postmenopausal women conducted at a Canadian university-affiliated hospital nutrition research centre from April 2005 to November 2006.InterventionParticipants were advised to consume either a low-carbohydrate vegan diet or a high-carbohydrate lacto-ovo vegetarian diet for 6 months after completing 1-month metabolic (all foods provided) versions of these diets. The prescribed macronutrient intakes for the low-carbohydrate and high-carbohydrate diets were: 26% and 58% of energy from carbohydrate, 31% and 16% from protein and 43% and 25% from fat, respectively.Primary outcomeChange in body weight.Results23 participants (50% test, 68% control) completed the 6-month ad libitum study. The approximate 4 kg weight loss on the metabolic study was increased to −6.9 kg on low-carbohydrate and −5.8 kg on high-carbohydrate 6-month ad libitum treatments (treatment difference (95% CI) −1.1 kg (−2.1 to 0.0), p=0.047). The relative LDL-C and triglyceride reductions were also greater on the low-carbohydrate treatment (treatment difference (95% CI) −0.49 mmol/L (−0.70 to −0.28), p<0.001 and −0.34 mmol/L (−0.57 to −0.11), p=0.005, respectively), as were the total cholesterol:HDL-C and apolipoprotein B:A1 ratios (−0.57 (−0.83, −0.32), p<0.001 and −0.05 (−0.09, −0.02), p=0.003, respectively).ConclusionsA self-selected low-carbohydrate vegan diet, containing increased protein and fat from gluten and soy products, nuts and vegetable oils, had lipid lowering advantages over a high-carbohydrate, low-fat weight loss diet, thus improving heart disease risk factors.Trial Registrationclinicaltrials.gov (http://www.clinicaltrials.gov/), #NCT00256516.

Dietary protein sources in male Golden Syrian hamsters fed a Western diet affect the gut microbiota, and soy protein may reduce lipogenesis through alterations of the gut microbial community.

No abstract