Systematic literature review evaluating evidence and mechanisms of action for platelet-rich plasma as an antibacterial agent.

Platelet rich plasma or PRP is a supraphysiologic concentrate of platelets derived by centrifugation and separation of whole blood components. Along with platelets and plasma, PRP contains various cell types including white blood cells (WBC)/leukocytes, both granulocytes (neutrophils, basophils, eosinophils) and agranulocytes (monocytes, lymphocytes). Researchers and clinicians have explored the application of PRP in wound healing and prevention of surgical wound infections, such as deep sternal wounds. We conducted this systematic literature review to evaluate the preclinical and clinical evidence for the antibacterial effect of PRP and its potential mechanism of action. 526 records were identified for screening. 34 unique articles were identified to be included in this literature review for data summary. Overall, the quality of the clinical trials in this review is low, and collectively qualify as Oxford level C. Based on the available clinical data, there is a clear trend towards safety of autologous PRP and potential efficacy in deep sternal wound management. The preclinical and bench data is very compelling. The application of PRP in treatment of wounds or prevention of infection with PRP is promising but there is a need for foundational bench and preclinical animal research to optimize PRP as an antibacterial agent, and to provide data to aid in the design and conduct of well-designed RCTs with adequate power to confirm antimicrobial efficacy of PRP in specific disease states and wound types.

The Phenylalanine Requirement of Elderly Men and Women Measured by Direct 13C Carbon Oxidation Method Is Similar to That of Young Adults.

BACKGROUND: The phenylalanine requirement of the elderly is not known. Current recommendations are based on studies in young adults and are derived from a combined estimate of the total aromatic amino acids, phenylalanine, and tyrosine. OBJECTIVES: The purpose of this study was to determine the dietary phenylalanine requirement of adults aged >65 y, using the direct amino acid oxidation method, by measuring the oxidation of l-[1-13C]phenylalanine to 13CO2 in response to graded phenylalanine intakes in the presence of excess tyrosine. METHODS: Twelve subjects (6 men, 6 women), aged 73.8 ± 6.7 y (mean ± SD) and with a BMI (in kg/m2) of 26.4 ± 4.8 and 25.2 ± 4.4 for men and women, respectively, were randomized to phenylalanine intakes ranging from 7.20 to 40.0 mg .kg-1 .d-1 for a total of 66 studies. Study diets were isocaloric and isonitrogenous, providing protein and energy at 1.0 g .kg-1 .d-1 and 1.5 × resting energy expenditure (REE), respectively. Protein was provided as an amino acid mixture patterned after egg protein, with an excess of tyrosine and alanine to balance the nitrogen as phenylalanine intakes were varied. Two days prior to the study day, subjects were adapted to a milkshake diet providing protein at 1.0 g.kg-1 .d-1 and energy at 1.7 × REE. The mean phenylalanine requirement was determined using biphase linear regression analysis, which identified a breakpoint in the F13CO2 in response to graded phenylalanine intakes. RESULTS: The mean and upper 95% CIs (approximating the recommended dietary allowance) of phenylalanine requirements were estimated to be 9.03 and 15.9 mg.kg-1 .d-1, respectively. CONCLUSION: These results are similar to previously derived estimates of 9.1 and 13.6 mg.kg-1 .d-1 in young adult men and suggest that higher protein needs of the elderly to stimulate similar muscle protein synthesis rates as young adults are not driven by an increased requirement for phenylalanine. This trial was registered at clinicaltrials.gov as NCT02971059.

Quantifying inadvertent thermal bowel injury from the monopolar instrument.

BACKGROUND: Insulation defects are observed in 3-39 % of laparoscopic instruments. Electrosurgical injuries due to insulation defects or capacitive coupling remain an issue in laparoscopic surgery with a prevalence of 0.6-5 per thousand cases. Shielded instruments with active electrode monitoring (AEM) have been postulated to prevent these injuries. The benefit of these instruments has not been quantified. Most bowel injuries are unrecognized intra-operatively. Injury is revealed only after the patient exhibits peritonitis symptoms and surgical intervention to repair the bowel is required. These injuries may result in devastating and costly complications or mortality. The extent of bowel injury possible with commonly used generator settings and associated energy output has never been histologically defined. Our objectives in this experimental study were: quantify and compare the energy released through insulation defects or capacitive coupling with standard unshielded monopolar versus shielded instruments with (AEM), determine energy required to cause a visible burn, and relate the histological burn depth to a given amount of energy. METHODS: Ex vivo porcine jejunum was used for tissue testing. An oscilloscope measured energy output from three common electrosurgical generators at recommended power settings with standard or AEM instruments with insulation defects and in capacitive coupling scenarios. Presence of a visible burn was noted, and depth of tissue damage for a given amount of energy was measured histologically. RESULTS: All samples that received ≥3.8 J of energy had visible burns. As little as 10 J caused full wall thickness burns. 3.8 J was exceeded at the 30- and 50-W power settings in every experimental scenario using standard monopolar instruments; AEM instruments never approached this much energy. CONCLUSIONS: Serious burn injury results from small amounts of energy leaked from standard instruments. AEM instruments appeared protective and did not leak sufficient energy to cause burn injuries to the bowel.

Effect of collagen and elastin content on the burst pressure of human blood vessel seals formed with a bipolar tissue sealing system.

BACKGROUND: Bipolar devices are routinely used to seal blood vessels instead of sutures and clips. Recent work examining the impact of vascular proteins on bipolar seal performance found that collagen and elastin (CE) content within porcine arteries was a significant predictor of a vessel's burst pressure (VBPr). This study examined seal performance across a range of human blood vessels to investigate whether a similar relationship existed. In addition, we compared VBPr and CE content between porcine and human blood vessels. Our primary hypothesis is that higher collagen-to-elastin ratio will predict higher VBPr in human vasculature. METHODS: In six cadavers, 185 blood vessels from nine anatomic locations were sealed using a bipolar electrosurgical system. A linear mixed model framework was used to evaluate the impact of vessel diameter and CE content on VBPr. RESULTS: The effect of CE ratio on VBPr is modified by vessel size, with CE ratio having larger influence on VBPr in smaller diameter vessels. Seal burst pressure of vessels 2-5 mm in diameter was significantly associated with their CE content. Comparison of average VBPr between species revealed porcine carotid and iliac arteries (440-670 mmHg) to be the best vessel types for predicting the seal strength of most human blood vessels (420-570 mmHg) examined. CONCLUSIONS: CE content significantly modified the seal strength of small to medium sized blood vessels but had limited impact on vessels >5 mm.

In search of the autologous clip: a case for experimental standardization.

BACKGROUND: In an effort to enable faster and, at times, more challenging surgeries without compromising patient or physician safety, medical device manufacturers have created myriad solutions to vascular ligation through the development of novel tools. The speed of development, FDA approval, and dissemination of these devices into the hands of surgeons often outpaces the ability of investigators to critically evaluate comparative effectiveness of these devices. DATABASE: The Medline database was searched for energy-based vessel ligation devices. To remove any perception bias against non-Covidien instruments, critical review was applied only to the devices manufactured by our company. CONCLUSIONS: We report on the variability present in published results and offer vital metrics for future studies. Standardized testing and reporting for measures of safety and efficacy of these surgical instruments awaits definition from a consensus group.

Effect of catechol O-methyltransferase val(158)met polymorphism on the p50 gating endophenotype in schizophrenia.

BACKGROUND: Studies have implicated prefrontal dopamine in cortical information filtering. Deficit in stimulus filtering, an endophenotype of schizophrenia, can be demonstrated using the auditory P50 paired-click gating paradigm. The role of prefrontal dopamine on P50 gating was investigated, using catechol-O-methyltransferase (COMT) valine (val)(158)methionine (met) polymorphism as a predictor of prefrontal dopamine activity. METHODS: Twenty-five comparison and 42 schizophrenia subjects underwent P50 gating measurement and COMT genotyping. RESULTS: In the combined sample, COMT polymorphism accounted for a unique 10% of gating variance (p = .02), after variance due to diagnosis, smoking status, and antipsychotic use was removed. Valine homozygous individuals exhibited the greatest gating deficit. CONCLUSIONS: Valine homozygous individuals are more likely to have gating deficits, supporting COMT as a genetic determinant of the P50 endophenotype, as well as a role for prefrontal dopamine in auditory filtering.