Brandon Lewis

Arginine Supplementation Is Well Tolerated but Does Not Enhance Mitogen-Induced Lymphocyte Proliferation in Elderly Nursing Home Residents with Pressure Ulcers

BACKGROUND Immune function declines with age, increasing risk for infection and delaying wound healing. Arginine enhances immune function and healing of standardized wounds in healthy elderly persons. The purpose of this study was to determine what level of arginine supplementation was orally and metabolically tolerated and effective in enhancing immune function in elderly persons with pressure ulcers. METHODS Residents with one or more pressure ulcers were recruited from two local nursing homes. Subjects were randomized to receive 0 g (n = 10; age, 82 +/- 3 years), 8.5 g (n = 11; 81 +/- 3 years), or 17 g (n = 11; 87 +/- 2 years) of supplemental arginine each day for 4 weeks. Oral tolerance, ie, absence of nausea, vomiting, abdominal distention, or diarrhea, was assessed daily. Metabolic tolerance was assessed weekly by evaluating serum electrolytes. Lymphocyte proliferation to phytohemagglutinin and interleukin 2 production were measured at baseline and after 4 weeks of supplementation as indicators of immune function. RESULTS Supplemental arginine significantly increased plasma arginine levels and was orally and metabolically tolerated with no complaints of abdominal distress or no clinically relevant changes in electrolyte levels among groups. Lymphocyte proliferation and interleukin 2 production were significantly different between nursing homes. When data from nursing homes were considered individually, arginine supplementation did not enhance the proliferative response. In subjects from nursing home 2 only, there was a 38% and 75% decrease (p < .05) in lymphocyte proliferation with 8.5 and 17 g of supplemental arginine, respectively. Interleukin 2 production was no different among supplementation groups. CONCLUSIONS Pharmacologic doses of arginine were well tolerated but did not enhance lymphocyte proliferation or interleukin 2 production in nursing home residents with pressure ulcers. CLINICAL RELEVANCY: Enteral formulas supplemented with pharmacologic levels of arginine are frequently administered to elderly persons. This study demonstrates that the very old can tolerate these nitrogen loads if baseline renal function is normal and fluid intake is encouraged. Further research needs to be completed investigating the effect of arginine supplementation on immune function in this population before recommending arginine use.

Detection and quantification of biotinylated proteins using the Storm 840 Optical Scanner

The use of the avidin-biotin interaction is becoming an increasingly common method for the detection of proteins. The use of fluorescence detection with avidin-biotin systems has the potential to greatly increase both the sensitivity and linearity of this type of analysis. In this report, three fluorescent systems were tested for their ability to detect biotinylated polypeptides in purified and complex biological samples. These systems include a Neutravidin-Alexa Fluor430 conjugate, an avidin-horseradish peroxidase conjugate with the ECL-Plus detection system, and an avidin-alkaline phosphatase conjugate with the ECF detection system. Biotinylated molecular weight standards, biotinylated bovine serum albumin, and rat liver homogenate were resolved by SDS-PAGE gel electrophoresis and transferred to polyvinyldifluoride membrane. Biotinylated polypeptides were then visualized on the Storm840 optical scanner. The Neutravidin-Alexa Fluor430 conjugate exhibited the lowest sensitivity, but displayed high linearity. The avidin-horseradish peroxidase and avidin-alkaline phosphatase conjugates, when combined with appropriate fluorescent substrates, exhibited much higher fluorescence, with the avidin-alkaline phosphatase ECF system displaying the highest sensitivity. All systems demonstrated an ability to reliably detect and quantify biotinylated polypeptides in purified as well as complex samples, given careful attention to conditions optimized for each system.

Antihypertensive effect of passion fruit peel extract and its major bioactive components following acute supplementation in spontaneously hypertensive rats

Extracts from leaves, peels or flowers of Passiflora are noted for their medicinal effects. Passiflora edulis peel extract (PFPE) has been proposed to lower blood pressure (BP); however, only indirect measurement techniques have been employed. To more accurately measure the effect of PFPE on hemodynamic parameters and determine the minimal effective dose, hemodynamic parameters were directly measured in spontaneously hypertensive rats (SHR) implanted with radiotelemeters. PFPE was given orally at 0, 2.5, 50 or 200 mg/kg body weight (BW) to determine the minimal effective dose. Once this dose was determined, the potential active components, edulilic acid (EA), anthocyanin fraction (AF) or γ-aminobutyric acid (GABA), were tested to determine which may contribute to the reductions in BP. The 50 mg PFPE/kg BW dose was the lowest dose that significantly reduced all hemodynamic parameters from baseline when compared to control. When the potential actives were provided at equivalent doses to those found in 50 mg PFPE/kg BW, the EA and AF significantly reduced all measured hemodynamic parameters from baseline when compared to control. GABA did not significantly affect any hemodynamic parameters compared to control and significantly increased heart rate. These direct measurements indicate that PFPE can decrease hemodynamic parameters in SHR and indicate that EA and AF are active compounds that contribute to the antihypertensive effects of PFPE supplementation. While these results are encouraging, detailed mechanistic studies are needed to determine the putative value of PFPE for blood pressure control in humans.