Noninvasive continuous blood pressure monitoring via superficial temporal artery tonometry

Abstract— Objective: Arterial blood pressure (BP) is one of the most important physiological indexes monitored in the perioperative period, yet all existing noninvasive monitoring methods are limited in either sampling rate, measuring site or accuracy. In this work, a systematic evaluation was conducted on a novel BP monitoring approach through the use of the superficial temporal artery tonometry (STAT) method and the corresponding developed BP monitoring system. Methods: Twenty-nine sessions of 30-minutes continuous BP monitoring during resting and during handgrips induced BP fluctuation were conducted in human subjects (n=10) simultaneously with the STAT method, Finapres Finometer and Pulse Transit Time (PTT) method. Results: Using Finapres Finometer as the gold standard for continuous BP, our proposed device resulted in 4.8 ± 2.2 mean absolute difference (MAD) during resting and 6.5 ± 3.4 MAD during handgrips, which significantly outperformed PTT, especially in handgrips. Correlation plots and Bland-Altman plots also suggest the same conclusion.Conclusion: BP monitoring via STAT was systematically evaluated and showed better performance than PTT. Significance: Noninvasive and continuous perioperative BP monitoring via STAT may be feasible and appropriate.

Use of Silica Based Materials as Modulators of the Lipase Catalyzed Hydrolysis of Fats under Simulated Duodenal Conditions

The effect of silica materials and their functionalization in the lipase catalyzed fat hydrolysis has been scarcely studied. Fifteen silica materials were prepared and their effect on the fat hydrolysis was measured, under simulated duodenal conditions, using the pH-stat method. The materials are composed of the combination of three supports (Stöber massive silica nanoparticles, Stöber mesoporous nanoparticles and UVM-7) and four surface functionalizations (methyl, trimethyl, propyl and octyl). In addition, the non-functionalized materials were tested. The functional groups were selected to offer a hydrophobic character to the material improving the interaction with the fat globules and the lipase. The materials are able to modulate the lipase activity and their effect depending on the support topology and the organic covering, being able to increase or reduce the fat hydrolysis. Depending of the material, relative fat hydrolysis rates of 75 to 140% in comparison with absence of the material were obtained. The results were analyzed by Partial Least Square Regression and suggest that the alkyl modified mesopores are able to improve the fat hydrolysis, by contrast the non-porous nanoparticles and the textural pores tend to induce inhibition. The effects are more pronounced for materials containing long alkyl chains and/or in absence of taurodeoxycholate.

Kinetic Models to Produce an Antioxidant by Enzymatic Hydrolysis of Bovine Plasma Protein Using a High Substrate Concentration

Background: The animal blood that is produced in a slaughterhouse is a potential source of inexpensive proteins used in the food industry around the world. However, 60% of it is surplus, and it ends with a negative environmental impact. Introduction: The enzymatic hydrolysis of proteins represents a good way to produce peptides with different biological activities. Methods: Enzymatic hydrolysis of bovine plasma with subtilisin at an alkaline pH and 61.5°C was performed using the pH-stat method. Experiments were conducted considering the effects of a high initial substrate concentration (So) and the enzyme/substrate ratio (E/S) minimizing the processing time necessary to obtain a specific degree of hydrolysis (DH). Results: The best conditions obtained were 42 g/L of So and 0.89 AU/g substrate of E/S until a DH of 20% in 11,1 ± 1,1 min was achieved to the tested conditions, which result in a fitted empirical polynomial equation of degree 3. Conclusion: A kinetic equation is established to relate the DH and the reaction time to a relative error of less than 5% in the fit, to obtain a good antioxidant product in an industrially interesting time. Additionally, the results suggest a good adjustment of the data with a determination coefficient (R2) of 0.9745 in validation.

Manufacturing Process, In Vivo and In Vitro Digestibility Assessment of an Enteral Feeding Product Hydrolyzed from Locally Available Ingredients Using Commercial Enzymes

A ready-for-use enteral feeding product was manufactured based on energy standard mixing using hydrolyzed products from local foods (i.e., loin pork, carrot, pumpkin, soybean, rice, and potato). When compared to enteral foods based on defined ingredients, the manufactured product is more cost-effective, appropriately functional and has similar physicochemical properties. Relative protein digestibility for in vitro value was tested by using enzyme pepsin, pH-drop and pH-stat method with three different enzymes. The product was shown to be easily digested with an in vivo digestibility value of 89.7%. Molecule sizes of components in the product ranged from 3.5 to 8.5 kDa, determined by SDS-PAGE, and the average molecular weight was 1.52 kDa, determined by Gel Permeation Chromatography (GPC) method. In terms of nutritional value, the product achieved a caloric density of 1 kcal/mL, dietary fibers of 1.48 g per 100 mL and provided both oligomeric and monomeric forms of protein. In addition, the product has the leucine: isoleucine: valine ratio of 2:1:1, thus facilitating the absorption of the protein. In conclusion, the manufactured enteral feeding product has been shown to be appropriate for providing nutritional support for patients.

Optimization of Multi-Enzyme Hydrolysis Process for Efficient Corn Gluten Meal Hydrolysis

In order to hydrolyze corn gluten meal efficiently, combinations of two or three out of three hydrolysis enzymes (protex6L, protex7L and papain) were used and the process parameters were optimized in this paper. The degree of hydrolysis of corn gluten meal was assayed by using pH-stat method. The ratio of enzymes was optimized and the effect of multi-enzyme hydrolysis was compared with that of single-enzyme hydrolysis. The result showed that the optimal ratio of protex6L and protex7L was 3:1, protex6L and papain was 6:5, protex7L and papain was 1:1, and the optimal ratio of protex6L, protex7L and papain was 4:1:1.The degree of hydrolysis and soluble protein content of multi-enzyme hydrolysis and single-enzyme hydrolysis were approximately equal, but multi-enzyme hydrolysis was timesaving.

Kinetic Analysis of Paper White Mud Dissolution at Constant pH

One of the most important steps in the wet limestone–gypsum flue gas desulfurization (WFGD) process is limestone dissolution, which provides the dissolved alkalinity necessary for SO2 absorption. Accurately evaluating the rate controlling step in sorbent dissolution process is important in the design and efficient operation of WFGD plants. In the present work, the kinetics of paper white mud(PWM) in dissolution process has been studied by using a pH-stat method. The results obtained indicated that PWM dissolution in WFGD conditions obeys the modified shrinking core model. PWM dissolution kinetics follows the film diffusion and surface reaction control and the rate controlling step of PWM is film diffusion control. The activation energies of PWM in film diffusion and surface reaction steps are 11.9±0.7 kJ/mol and 13.7±1.3 kJ/mol, respectively.

Effect of temperature and enzyme/substrate ratio on the hydrolysis of pea protein isolates by trypsin

Two pea protein isolates, Pisane and Propulse, were hydrolysed by trypsin. The degree of hydrolysis (DH) was computed using a pH-stat method. Enzymatic treatment of the pea protein isolates was conducted at four different temperatures, namely 35, 40, 45 and 50°C. The relationship between DH and E/S ratio was studied at 50°C and at four different E/S ratios; these were 5, 15, 25, 35 mAU/g (AU – Anson unit). For Pisane the highest value of the final DH (10.4%) was obtained at 45°C, whereas for Propulse the optimal temperature was 50°C and a DH value of 13.2% was attained. In the case of Pisane, the highest DH (11.5%) was recorded if the enzyme/substrate ratio was 35 mAU/g whereas for Propulse, the highest DH (13.2%) was observed at an E/S ratio of 15 mAU / g.