Fabrication of unconventional inertial microfluidic channels using wax 3D printing.

Inertial microfluidics has emerged over the past decade as a powerful tool to accurately control cells and microparticles for diverse biological and medical applications. Many approaches have been proposed to date in order to increase the efficiency and accuracy of inertial microfluidic systems. However, the effects of channel cross-section and solution properties (Newtonian or non-Newtonian) have not been fully explored, primarily due to limitations in current microfabrication methods. In this study, we overcome many of these limitations using wax 3D printing technology and soft lithography through a novel workflow, which eliminates the need for the use of silicon lithography and polydimethylsiloxane (PDMS) bonding. We have shown that by adding dummy structures to reinforce the main channels, optimizing the gap between the dummy and main structures, and dissolving the support wax on a PDMS slab to minimize the additional handling steps, one can make various non-conventional microchannels. These substantially improve upon previous wax printed microfluidic devices where the working area falls into the realm of macrofluidics rather than microfluidics. Results revealed a surface roughness of 1.75 μm for the printed channels, which does not affect the performance of inertial microfluidic devices used in this study. Channels with complex cross-sections were fabricated and then analyzed to investigate the effects of viscoelasticity and superposition on the lateral migration of the particles. Finally, as a proof of concept, microcarriers were separated from human mesenchymal stem cells using an optimized channel with maximum cell-holding capacity, demonstrating the suitability of these microchannels in the bioprocessing industry

Numerical and Experimental Study of Cross-Sectional Effects on the Mixing Performance of the Spiral Microfluidics.

Mixing at the microscale is of great importance for various applications ranging from biological and chemical synthesis to drug delivery. Among the numerous types of micromixers that have been developed, planar passive spiral micromixers have gained considerable interest due to their ease of fabrication and integration into complex miniaturized systems. However, less attention has been paid to non-planar spiral micromixers with various cross-sections and the effects of these cross-sections on the total performance of the micromixer. Here, mixing performance in a spiral micromixer with different channel cross-sections is evaluated experimentally and numerically in the Re range of 0.001 to 50. The accuracy of the 3D-finite element model was first verified at different flow rates by tracking the mixing index across the loops, which were directly proportional to the spiral radius and were hence also proportional to the Dean flow. It is shown that higher flow rates induce stronger vortices compared to lower flow rates; thus, fewer loops are required for efficient mixing. The numerical study revealed that a large-angle outward trapezoidal cross-section provides the highest mixing performance, reaching efficiencies of up to 95%. Moreover, the velocity/vorticity along the channel length was analyzed and discussed to evaluate channel mixing performance. A relatively low pressure drop (<130 kPa) makes these passive spiral micromixers ideal candidates for various lab-on-chip applications

The Incidence Rate of Vasovagal Reactions and Its Effective Factors among Blood Donors in Mashhad Blood Transfusion Centers

Aims: Vasovagal reaction is one of the most common complications of blood donation, this study was conducted to determine the prevalence of vasovagal reactions and its effective factors among blood donors in Mashhad blood transfusion centers. Materials & Methods: This case-control study was performed on 657 blood donors in Mashhad's four blood transfusion centers during 6 months. The donors who had vasovagal reactions were in the case group (218 cases), and 439 donors who did not respond to vasovagal were in the control group. The age, BMI, blood pressure, pulse rate, hematocrit and vasovagal response variables were studied. Data were analyzed by SPSS 11.5 using Chi-square and Mann-Whitney tests. Findings: The incidence of vasovagal reactions in the six months was 2.16%. The mean age in the case group was significantly lower than the control group (p<0.001). Vasovagal reactions were significantly higher in women and in first-time donors, as well as in those with anxiety and in subjects with lower BMI (p<0.001). The mean reduction in arterial pressure after blood donation was significantly higher in the case group than in the control group (p<0.001). Conclusion: The incidence of vasovagal reactions is dependent on several factors, including age, sex, BMI, and blood pressure, and with more care from high-risk donors, it can be approximately prevented from vasovagal reaction and increased the possibility of returning to blood donation

Objective assessment of bradykinesia in Parkinson’s disease using evolutionary algorithms: clinical validation

Background: There is an urgent need for developing objective, effective and convenient measurements to help clinicians accurately identify bradykinesia. The purpose of this study is to evaluate the accuracy of an objective approach assessing bradykinesia in finger tapping (FT) that uses evolutionary algorithms (EAs) and explore whether it can be used to identify early stage Parkinson’s disease (PD). Methods: One hundred and seven PD, 41 essential tremor (ET) patients and 49 normal controls (NC) were recruited. Participants performed a standard FT task with two electromagnetic tracking sensors attached to the thumb and index finger. Readings from the sensors were transmitted to a tablet computer and subsequently analyzed by using EAs. The output from the device (referred to as "PD-Monitor") scaled from − 1 to +1 (where higher scores indicate greater severity of bradykinesia). Meanwhile, the bradykinesia was rated clinically using the Movement Disorder Society- Sponsored Revision of the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) FT item. Results: With an increasing MDS-UPDRS FT score, the PD-Monitor score from the same hand side increased correspondingly. PD-Monitor score correlated well with MDS-UPDRS FT score (right side: r = 0.819, P = 0.000; left side: r = 0.783, P = 0.000). Moreover, PD-Monitor scores in 97 PD patients with MDS-UPDRS FT bradykinesia and each PD subgroup (FT bradykinesia scored from 1 to 3) were all higher than that in NC. Receiver operating characteristic (ROC) curves revealed that PD-Monitor FT scores could detect different severity of bradykinesia with high accuracy (≥89.7%) in the right dominant hand. Furthermore, PD-Monitor scores could discriminate early stage PD from NC, with area under the ROC curve greater than or equal to 0.899. Additionally, ET without bradykinesia could be differentiated from PD by PD-Monitor scores. A positive correlation of PD-Monitor scores with modified Hoehn and Yahr stage was found in the left hand sides. Conclusions: Our study demonstrated that a simple to use device employing classifiers derived from EAs could not only be used to accurately measure different severity of bradykinesia in PD, but also had the potential to differentiate early stage PD from normality

Vitamin E improved redox homeostasis in heart and aorta of hypothyroid rats

Objectives. The objective of this study was to evaluate the effect of vitamin E on the oxidative stress parameters and antioxidant defense enzymes in the heart and aorta of 6-n-propylthiouracil (PTU)-induced hypothyroid rats. Methods. The animals were divided into 4 experimental groups: Group 1 (Euthyroid) received tap water, Group 2 (Hypothyroid) received 0.05 % of PTU in dissolved in their drinking water, Group 3 (PTU+Vit E) hypothyroid rats treated with vitamin E, and Group 4 (Euthyroid+Vit E). Vitamin E was injected daily (20 mg/kg) to groups 3 and 4 via daily gavage for 6 weeks. Malondialdehyde (MDA) levels, total thiol levels, and the activities of Cu, Zn-superoxide dismutase (SOD) and catalase (CAT) were evaluated in the aortic and cardiac tissues. Results. A significant decrease of thyroxine (T4) serum levels confirmed hypothyroidism in rats, which received PTU. The MDA level increased and total thiol level decreased in the hypothyroid group compared to control group (p<0.001). Th e activities of SOD and CAT significantly decreased in the hypothyroid rats in comparison to the control. Vitamin E treatment resulted in increased levels of total thiol, SOD, and CAT within aortic and cardiac tissues and decreased levels of MDA in comparison with the hypothyroid group (p<0.01−p<0.001). Conclusions. PTU-induced hypothyroidism resulted in oxidative stress. Chronic administration of vitamin E to hypothyroid rats decreased the oxidative stress markers in the aortic and cardiac tissues

Vitamin E improved redox homeostasis in heart and aorta of hypothyroid rats

Objectives. The objective of this study was to evaluate the effect of vitamin E on the oxidative stress parameters and antioxidant defense enzymes in the heart and aorta of 6-n-propylthiouracil (PTU)-induced hypothyroid rats. Methods. The animals were divided into 4 experimental groups: Group 1 (Euthyroid) received tap water, Group 2 (Hypothyroid) received 0.05 % of PTU in dissolved in their drinking water, Group 3 (PTU+Vit E) hypothyroid rats treated with vitamin E, and Group 4 (Euthyroid+Vit E). Vitamin E was injected daily (20 mg/kg) to groups 3 and 4 via daily gavage for 6 weeks. Malondialdehyde (MDA) levels, total thiol levels, and the activities of Cu, Zn-superoxide dismutase (SOD) and catalase (CAT) were evaluated in the aortic and cardiac tissues. Results. A significant decrease of thyroxine (T4) serum levels confirmed hypothyroidism in rats, which received PTU. The MDA level increased and total thiol level decreased in the hypothyroid group compared to control group (p<0.001). Th e activities of SOD and CAT significantly decreased in the hypothyroid rats in comparison to the control. Vitamin E treatment resulted in increased levels of total thiol, SOD, and CAT within aortic and cardiac tissues and decreased levels of MDA in comparison with the hypothyroid group (p<0.01−p<0.001). Conclusions. PTU-induced hypothyroidism resulted in oxidative stress. Chronic administration of vitamin E to hypothyroid rats decreased the oxidative stress markers in the aortic and cardiac tissues

The effects of aqueous-ethanol extract of Achillea wilhelmsii on gastric acid secretion at basal, vagotomized and vagal-stimulated conditions

Background: It has been shown that Achillea wilhelmsii, a plant used in traditional medicine to treat gastrointestinal disorders, has the antibacterial, antioxidant and antispasmodic effects. However, the effects of Achillea wilhelmsii on gastric acid secretion have not been detected yet. Materials and Methods: Twenty four male Wistar rats (200-250 g) were randomly divided into two groups (case and control). After anesthesia by sodium thiopental (50 mg/kg, ip) tracheostomy, laparatomy and gastrodeodenostomy were performed for each rat. Gastric secretions were collected through a tube inserted in the stomach and extended toward duodenum. Using the maceration method, different doses of the extract (0.5, 1, 2 mg/kg) were prepared in a volume of 1 ml. The same amount of normal saline was used in control group. Two samples of the gastric secretion were collected by 15 minute intervals. The total titrable acid was measured by a titrator. The data were analyzed using unpaired t-test and the results were reported with a significance level of 0.05. Results: The extract significantly inhibited the basal acid secretion in a dose-dependent manner. A concentration of 2 mg/kg of the extract showed a stimulatory effect on acid secretion. Vagotomy prevented the inhibitory effect of extract on gastric acid secretion. There was no difference between the effects of extract on control and stimulated vague group. Conclusion: The results indicated the inhibitory effect of extract on basal acid secretion. The comparison of extract effect on basal acid secretion at basal and vagotomized conditions showed that the inhibitory effect of the extract was mediated by the inhibition of gastric vagal activity. The extract could not inhibit the stimulated gastric acid secretion

Hypotensive effect of Achillea wilhelmsii aqueous-ethanolic extract in rabbit

Objective: For many years in herbal medicine the antihypertensive and lowering blood lipid properties of Achillea wilhelmsii (A. wilhelmsii) have been suggested. In the present study the impacts of the plant extract on rabbit’s blood pressure and heart rate have been investigated. Materials and Methods: Twelve NWZ rabbits weighed 2-3 kg were randomly divided into two groups of 6 rabbits. The test group received A. wilhelmsii extract (20, 40 and 80 mg/kg) and the control group received normal saline by jugular vein cannula. Blood pressure and heart rate were measured via carotid cannula using pressure transducer connected to a power lab system. Results: The blood pressure was significantly decreased (16.7± 1.4 mmHg) in 80 mg/kg dose of the extract (

Cardioprotective effects of Achillea wilhelmsii on the isolated rat heart in ischemia–reperfusion

Context: There are some reports about protective effects of Achillea on the heart. Objective: We investigated the effect of Achillea wilhelmsii extract on cardiac function during ischemia–reperfusion (I/R) injury in the isolated rat heart. Materials and methods: 60 male Wistar rats were randomly divided into 6 groups; 1: Control group, 2: Control-ischemia (CI) 3: vitamin C (10 mg/kg), 4–6: Extract groups (E 100, E 200 and E 400 mg/kg). The animals received normal saline, vitamin C or A. wilhelmsii extract orally for 4 weeks. At the end of the treatment, the hearts were subjected to in vitro I/R Injury (20 min of global ischemia, followed by 40 min of reperfusion, Langendorff's mode). Heart rate (HR) and left ventricular pressure (LVP) were measured using a pressure transducer connected to a data acquisition system. Lactate dehydrogenase (LDH) and creatine kinase (CK) activities in the effluent were measured to determine the myocardial injury degree. The malondialdehyde (MDA), total thiol groups (-SH), superoxide anion dismutase (SOD) and catalase (CAT) in myocardial tissue were detected to determine the oxidative stress degree. Results: Pretreatment with Achillea wilhlemsii significantly decreased the LDH, CK activities, and MDA level, while it increased the LVDP, ±dp/dtmax, rate-pressure product (RPP), SH groups, SOD and CAT activities, and also the coronary artery flow. Discussion and conclusion: Our findings indicated that Achillea wilhelmsii could provide protection for heart against the I/R injury which may be related to the improvement of myocardial oxidative stress states