The effects of whey proteins, their peptides and amino acids on vascular function.

Cardiovascular diseases (CVD) are a significant and growing burden on global health services, and it is now accepted that impairment of vascular function represents a major preliminary step in the development of CVD. There is considerable interest in identifying both causal factors of impaired vascular function, as well as related nutritional factors that may lower the risk of developing CVD, and food-derived bioactive peptides and amino acids have emerged as one such area. Dairy foods contain two groups of proteins, whey proteins and caseins, which represent a rich source of bioactive peptides that are released during food processing and/or digestion. These peptides have a number of physiological activities including the potential to reduce blood pressure. Research, including acute and longer-term randomised controlled trials, animal models and in vitro models has demonstrated the potential impact of dairy proteins on vascular function. The purpose of this paper is to narratively review the evidence, primarily from randomised controlled trials, examining the effects of whey proteins, their peptides and amino acids on vascular function and related issues including blood pressure. In addition, it will explore the potential underlying mechanisms responsible for these effects. It concludes that there is increasing evidence that whey proteins, and notably the bioactive peptides and amino acids released during their digestion, can have beneficial effects on aspects of vascular function and thus contribute to CVD risk reduction. It also highlights a number of beneficial effects of whey proteins including those on blood pressure, arterial stiffness, nitric oxide production and inflammation.

Validation of clinical techniques for verification of uniform attenuation earplugs.

OBJECTIVE: Uniform attenuation earplugs (UAE) theoretically provide near even attenuation across frequencies when built to a manufacturer's specifications. Unfortunately, there is no current research available confirming if custom-molded uniform attenuation earplugs (UAE) are made to specifications nor is there guidance available on clinical methods of measuring attenuation of uniform attenuation earplug (UAE) devices. The goal of this study was to evaluate different procedures for UAE verification and to determine the most accurate clinically accessible verification protocol. DESIGN: Attenuation was measured using probe microphone techniques, as well as real-ear attenuation at threshold (REAT) measurements under circumaural earphones, soundfield speakers and supra-aural earphones. Comparisons were made to a reference system created in the laboratory. STUDY SAMPLE: Seventeen adult participants, totaling 30 ears. RESULTS: The results of this study demonstrate that the REAT measured in the soundfield using a narrowband noise stimulus with masking in the contralateral ear is currently the most accurate and widely available method of verifying UAEs. CONCLUSIONS: Factoring in clinical efficiency, the authors of this study recommend verifying attenuation levels using a soundfield REAT procedure as best clinical practice. In addition, the data suggests that REAT measurements under circumaural earphones are an acceptable second choice method.