Evaluation of a combined reflectance photoplethysmography and laser Doppler flowmetry surface probe

Photoplethysmographic (PPG) signals were recorded from the fingers of 16 healthy volunteers with periods of timed and forced respiration. The aim of this pilot study was to compare estimations of arterial oxygen saturation (SpO2) recorded using a dedicated pulse oximetry system while subjects were breathing regularly with and without a mouthpiece containing a flow resistor. The experiments were designed to mimic the effects of mechanical ventilation in manaesthetized patients. The effect of estimated airway pressures of ±15 cmH2O caused observable modulation in the recorded red and PPG signals. SpO2 values were calculated from the pre-recorded PPG signals. Mean SpO2 values were 95.4% with the flow resistor compared with 97.3% with no artificial resistance, with statistical significance demonstrated using a Student’s t-test (P = 0.006)

Evaluation of optical interference in a combined measurement system used for assessment of tissue blood flow

A dual-wavelength pulse oximetry system combined with laser Doppler was developed for the assessment of perfusion. Red and infrared PPG and Doppler signals were recorded from a healthy volunteer in three studies at different measurement sites to investigate the interference between PPG and laser Doppler flowmetry (LDF). Good quality photoplethysmographic (PPG) and Doppler signals were detected simultaneously using this combined probe from the skin of the finger. The influence of the PPG light sources on LDF measurements was investigated; also the influence of the LDF light sources to the PPG measurements was studied. In the worst case, the apparent change in PPG amplitude when the LDF system was switched on was less than 8%, and the change in LDF flux amplitude when the PPG system was switched on was 14.7%

Performance of a novel optical sensor for intraoperative assessment of intestinal viability - 'proof of principle' study

Introduction: Objective assessment of intestinal viability during surgery will allow surgeons to make informed decisions on the safety of intestinal anastomosis and to predict anastomotic related complications.1We investigated the performance of a novel dual sensor incorporating two established methods – photoplethysmography (PPG) and laser Doppler flowmetry (LDF) in a ‘proof of principle’ study. Method: Using the new probe, infrared and red PPG amplitude and LDF flux of the bowel surface were recorded by LDF and PPG simultaneously in 30 patients undergoing large bowel resection with or without anastomosis. Each patient had measurements at eight different time points: before and after colonic mobilisation, over the tumour, before and after ligation of major vascular pedicle, immediately before and after anastomosis (+/- 5 min) at distal and proximal limbs. Both laparoscopic and open resectional cases were included. The differences between the mean amplitude and flux between different measurements were analysed. Results: Twenty four laparoscopic and six open bowel resection cases had a total of 121 measurements recorded using the new probe. The mean IR AC amplitude in pre-ligation was 433 (± 189) mV and the mean IR AC in post ligation was 301 (± 152) mV. A statistically significant difference (P = 0.047) was observed between pre-ligation and post-ligation for the mean infrared PPG amplitude (student’s t-test). A considerable difference in mean amplitude between pre and post ligation for the red PPG was also observed (the mean amplitude for the red PPG fell by –25.6%). The amplitude of the infrared PPG increased after anastomosis by 38.2% at the proximal site and by 37.8% at the distal site. The amplitude of the red PPG also increased after anastomosis (by 6.3%) at the proximal site although the equivalent increase was not seen at the distal site. The LDF measurements did not follow the same pattern of the changes seen in PPG amplitude. Conclusion: The preliminary results show that simultaneous PPG/LDF measurements from a combined sensor is feasible and provide useful information on changes in pulse volume and blood flow. Although the differences in PPG amplitude achieved statistical significance, the LDF measurements produced confounding results, perhaps explained by motion artefacts. Further refinements in design of the probe are required to improve the probe-tissue optical interface and reduce motion artefact

Intraoperative monitoring of intestinal viability: Evaluation of a new combined sensor

A dual wavelength photoplethysmography (PPG) and laser Doppler flowmetry (LDF) sensor was developed to investigate the suitability of these techniques for monitoring bowel viability intraoperatively. Clinical measurements were obtained from thirty patients undergoing bowel surgery. Three measurements were performed at different stages of the operation. The amplitude of infrared PPG decreased from the baseline measurement to the pre-anastomosis measurement by 36% and LDF flux decreased by 21% for the same measurements. An increase of 33% in amplitude for infrared PPG was observed from the pre-anastomotic to post-anastomosis measurement; the equivalent increase was not seen for LDF flux. The results revealed that the sensor could potentially indicate changes in perfusion and blood flow at critical phases of surgery, thereby assisting in the early detection of inadequate blood supply in bowel tissue. The results also suggest that laser Doppler is more sensitive to movement artefact compared to PPG

Evaluation of acute and sub-chronic toxicity of Semelil (ANGIPARS�), a new phytotherapeutic drug for wound healing in rodents

Semelil (ANGIPARS�), an herbal formulation containing Melilotus officinalis extract, is a novel compound being developed for treatment of chronic wounds, particularly diabetic foot ulcers. The purpose of this study was to investigate toxicological, pharmacological, and pathomorphological effects of I.M. and I.P. administration of Semelil in animals. The acute toxicity parameters of Semelil diluted in normal saline (1:10 or 1:5) were determined after a single injection into BALB/c mice and Wistar rats in two steps. First, the LD50 was approximately assessed and then the precise lethal dose indices were estimated by the probit-analysis method. Specific single-dose effects of Semelil were monitored for clinical signs of toxicity, including general state of the animals, changes in their behavior, hematological and biochemical parameters for 14 days after drug administration. Then, subacute-chronic toxicity was evaluated in rats treated with Semelil for 3 months. In acute toxicity study, the calculated LD50 for drug diluted at 1:5 was in the range of 44-52 ml/kg. The adverse effects at drug doses close to the LD50 included depressed mood, narcosis, and sleep. No adverse pharmacological or toxicological effects of the drug diluted at 1:10 and administered in the single-dose (25-50 ml/kg body wt.) or chronically (daily doses of 0.07 and 0.21 ml/kg body wt.) were noted. Thus, the animal studies demonstrated a favorable safety profile for the phytotherapeutic Semelil

Comparative evaluation of hydrogen peroxide sporicidal efficacy bdifferent standard test methods

Background and Objectives: There are different sporicidal standard tests with various specifications to deal with products that are claimed for sporicidal activity. The aim of this study was to compare the 7 H2O2 sporicidal efficacy against Bacillus subtilis spores using different standard test methods. Materials and Methods: The 7 H2O2 sporicidal efficacy against Bacillus subtilis spores was determined according to the AOAC MB-15-04 standard of carrier test and two standard suspension tests (BS EN 13704, AFNOR NF 72-230) in both clean and dirty conditions and by using different interfering substances including bovine serum albumin, yeast extract and skimmed milk. Results: The results of suspension tests with 3 � 105 and 2 � 107 CFU/ml of B. subtilis spore concentration demonstrated that the higher spore counts lead to lower efficacy of 7 H2O2. Also, the sporicidal activity of 7 H2O2 was reduced in the presence of interfering substances. Bovine serum albumin, yeast, and skimmed milk showed similar interfering effects in suspension test with 3 � 105 CFU/ml. While, in suspension tests with higher initial spore count (2 � 107 CFU/ml) severity of interfering effects were intensified and distinct. Our results indicated that the carrier sporicidal test in comparison with suspension tests required more contact time to kill B. subtilis spores. Conclusion: The results of this study showed that it is reasonable to use interfering substances and inoculated carriers in accordance with actual conditions of product usage in a sporicidal test. Interfering substances may reduce the contact surface between H2O2 and test spores; therefore, the sporicidal efficacy of H2O2 was diminished. So applying suspension test in clean condition to verify the claim of sporicidal activity is strongly discouraged. © 2020, Tehran University of Medical Science. All rights reserved

Co-optimized bidding strategy of an integrated wind-thermal-photovoltaic system in deregulated electricity market under uncertainties

Clean Energy sources, such as wind and solar, have become an inseparable part of today's power grids. However, the intermittent nature of these sources has become the greatest challenge for their owners, which makes the bidding in the restructured electricity market more challenging. Hence, the main goal of this paper is to propose a novel multi-objective bidding strategy framework for a wind-thermal-photovoltaic system in the deregulated electricity market for the first time. Contrary to the existing bidding models, in the proposed model, two objective functions are taken into account that the first one copes with profit maximization while the second objective function concerns with emission minimization of thermal units. The proposed multi-objective optimization problem is solved using the weighted sum approach. The uncertainties associated with electricity market prices and the output power of renewable energy sources are characterized by a set of scenarios. Ultimately, in order to select the best-compromised solution among the obtained Pareto optimal solutions, two diverse approaches are applied. The proposed bidding strategy problem is being formulated and examined in various modes of joint and disjoint operation of dispatchable and non-dispatchable energy sources. Simulation results illustrate that not only the integrated participation of these resources increases the producer's expected profit, but also decreases the amount of the produced pollution by the thermal units.© 2019 Elsevier. This manuscript version is made available under the Creative Commons Attribution–NonCommercial–NoDerivatives 4.0 International (CC BY–NC–ND 4.0) license, https://creativecommons.org/licenses/by-nc-nd/4.0/fi=vertaisarvioitu|en=peerReviewed

Phenotypic and genotypic evaluation of fluoroquinolone resistance in clinical isolates of Staphylococcus aureus in Tehran

Background: Fluoroquinolones are broad-spectrum antibiotics widely used in the treatment of bacterial infections such as Staphylococcus aureus isolates. Resistance to these antibiotics is increasing. Material/Methods: The occurrence of mutations in the grlA and gyrA loci were evaluated in 69 fluoroquinolone-resistant S. aureus isolates from 2 teaching hospitals of Tehran University of Medical Sciences. Results: Out of the 165 S. aureus isolates, 87 (52.7) were resistant to methicillin and 69 (41.8) were resistant to fluoroquinolone. Fluoroquinolone-resistant S. atoms isolates had a mutation at codon 80 in the grlA gene and different mutational combinations in the gyrA gene. These mutational combinations included 45 isolates at codons 84 and 86,23 isolates at codons 84,86 and 106 and 1 isolate at codons 84, 86 and 90. Fluoroquinolone-resistant S. aureus isolates were clustered into 33 PFGE types. Conclusions: The findings of this study show that the fluoroquinolone-resistant S. aureus strains isolated in the teaching hospitals in Tehran had multiple mutations in the QRDRs region of both grlA and gyrA genes