scholarly journals A methodological approach for quantifying and characterizing the stability of agitated saline contrast: implications for quantifying intrapulmonary shunt

2016 ◽  
Vol 121 (2) ◽  
pp. 568-576 ◽  
Author(s):  
Heather K. Hackett ◽  
Lindsey M. Boulet ◽  
Paolo B. Dominelli ◽  
Glen E. Foster
Keyword(s):  
Transit Time ◽  
Methodological Approach ◽  
Contrast Echocardiography ◽  
Acoustic Intensity ◽  
Suitable Alternative ◽  
Transit Times ◽  
Flow Through ◽  
Vitro Model ◽  
The Stability

Agitated saline contrast echocardiography is often used to determine blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA). We applied indicator dilution theory to time-acoustic intensity curves obtained from a bolus injection of hand-agitated saline contrast to acquire a quantitative index of contrast mass. Using this methodology and an in vitro model of the pulmonary circulation, the purpose of this study was to determine the effect of transit time and gas composition [air vs. sulphur hexafluoride (SF6)] on contrast conservation between two detection sites separated by a convoluted network of vessels. We hypothesized that the contrast lost between the detection sites would increase with transit times and be reduced by using contrast bubbles composed of SF6. Changing the flow and/or reducing the volume of the circulatory network manipulated transit time. Contrast conservation was measured as the ratio of outflow and inflow contrast masses. For air, 53.2 ± 3.4% (SE) of contrast was conserved at a transit time of 9.25 ± 0.02 s but dropped to 16.0 ± 1.0% at a transit time of 10.17 ± 0.06 s. Compared with air, SF6 contrast conservation was significantly greater ( P < 0.05) with 114.3 ± 2.9% and 73.7 ± 3.3% of contrast conserved at a transit time of 10.39 ± 0.02 s and 13.46 ± 0.04 s, respectively. In summary, time-acoustic intensity curves can quantify agitated saline contrast, but loss of contrast due to bubble dissolution makes measuring Q̇IPAVA across varying transit time difficult. Agitated saline composed of SF6 is stabilized and may be a suitable alternative for Q̇IPAVA measurement.

Effects of adenosine on pressure-flow relationships in an in vitro model of compartment syndrome

1997 ◽  
Vol 82 (3) ◽  
pp. 755-759 ◽  
Author(s):  
Ian Shrier ◽  
Ari Baratz ◽  
Sheldon Magder
Keyword(s):  
Compartment Syndrome ◽  
Gastrocnemius Muscle ◽  
In Vitro Model ◽  
Adenosine Infusion ◽  
Pressure Flow ◽  
Adenosine Concentration ◽  
Flow Through ◽  
The Difference ◽  
Vitro Model

Shrier, Ian, Ari Baratz, and Sheldon Magder. Effects of adenosine on pressure-flow relationships in an in vitro model of compartment syndrome. J. Appl. Physiol. 82(3): 755–759, 1997.—Blood flow through skeletal muscle is best modeled with a vascular waterfall at the arteriolar level. Under these conditions, flow is determined by the difference between perfusion pressure (Pper) and the waterfall pressure (Pcrit), divided by the arterial resistance (Ra). By pump perfusing an isolated canine gastrocnemius muscle ( n = 6) after it was placed within an airtight box, with and without adenosine infusion, we observed an interaction between the pressure surrounding a muscle (as occurs in compartment syndrome) and baseline vascular tone. We titrated adenosine concentration to double baseline flow. We measured Pcrit and Ra at box pressures (Pbox), which resulted in 100 (Pbox = 0), 90, 75, and 50% flow without adenosine; and 200, 180, 150, 100, and 50% flow with adenosine. Without adenosine, each 10% decline in flow was associated with a 5.7 mmHg increase in Pcrit ( P < 0.01). With adenosine, the same decrease in flow was associated with a 2.6-mmHg increase in Pcrit ( P < 0.01). Values of Pcrit at 50% of flow were almost identical. Each 10% decrease in flow was also associated with 2.2% increase in Ra with or without adenosine ( P < 0.001). Ra decreased with adenosine infusion ( P < 0.05), and there was no interaction between adenosine and flow ( P > 0.9). We conclude that increases in pressure surrounding a muscle limit flow primarily through changes in Pcrit with and without adenosine-induced vasodilation. The interaction between Pbox and adenosine with respect to Pcrit but not Ra suggests that Pbox affects the tone of the vessels responsible for Pcrit but not Ra.

scholarly journals The Swallowing Characteristics of Thickeners, Jellies and Yoghurt Observed Using an In Vitro Model

Dysphagia ◽  
2019 ◽  
Vol 35 (4) ◽  
pp. 685-695 ◽  
Author(s):  
Simmi Patel ◽  
William J. McAuley ◽  
Michael T. Cook ◽  
Yi Sun ◽  
Shaheen Hamdy ◽  
...  
Keyword(s):  
Transit Time ◽  
Mechanical Model ◽  
Xanthan Gum ◽  
In Vitro Model ◽  
High Concentration ◽  
High Concentrations ◽  
Vitro Model ◽  
Thickening Agents

Abstract Drinks and foods may be thickened to improve swallowing safety for dysphagia patients, but the resultant consistencies are not always palatable. Characterising alternative appetising foods is an important task. The study aims to characterise the in vitro swallowing behaviour of specifically formulated thickened dysphagia fluids containing xanthan gum and/or starch with standard jellies and yoghurt using a validated mechanical model, the “Cambridge Throat”. Observing from the side, the model throat can follow an experimental oral transit time (in vitro-OTT) and a bolus length (BL) at the juncture of the pharynx and larynx, to assess the velocity and cohesion of bolus flow. Our results showed that higher thickener concentration produced longer in vitro-OTT and shorter BL. At high concentration (spoon-thick), fluids thickened with starch-based thickener showed significantly longer in vitro-OTT than when xanthan gum-based thickener was used (84.5 s ± 34.5 s and 5.5 s ± 1.6 s, respectively, p < 0.05). In contrast, at low concentration (nectar-like), fluids containing xanthan gum-based thickener demonstrated shorter BL than those of starch-based thickener (6.4 mm ± 0.5 mm and 8.2 mm ± 0.8 mm, respectively, p < 0.05). The jellies and yoghurt had comparable in vitro-OTT and BL to thickeners at high concentrations (honey-like and spoon-thick), indicating similar swallowing characteristics. The in vitro results showed correlation with published in vivo data though the limitations of applying the in vitro swallowing test for dysphagia studies were noted. These findings contribute useful information for designing new thickening agents and selecting alternative and palatable safe-to-swallow foods.

scholarly journals Aortic flow below and visceral circulation during aortic counterpulsation: Evaluation of an in vitro model

Perfusion ◽  
2020 ◽  
pp. 026765912097864
Author(s):  
Monique MJ de Jong ◽  
Orlando Parise ◽  
Francesco Matteucci ◽  
Marcel Rutten ◽  
Maxime Devos ◽  
...  
Keyword(s):  
Systemic Circulation ◽  
Cardiovascular Model ◽  
Mock Circulation ◽  
Bland Altman Method ◽  
Heart Contraction ◽  
Vitro Model ◽  
The Stability ◽  
Number Of Cycles

Introduction: This study aimed to test a computer-driven cardiovascular model for the evaluation of the visceral flow during intra-aortic balloon pump (IABP) assistance. Methods: The model includes a systemic and pulmonary circulation as well as a heart contraction model. The straight polyurethane tube aorta had a single visceral while four windkessel components mimicked resistance compliance of the brachiocephalic, renal and sub-mesenteric, pulmonary, and systemic circulation. Twelve flow probes were placed in the circuit to measure pressures and flows with the IABP on and off. Results: With the balloon off, the meantime to reach the steady state was 48 ± 16 s; with the balloon on, this figure was 178 ± 20 s. The stability of pressure and flow signals was obtained after 72 ± 11 min. The number of cycles of stability of the system was 93 [86–103]. Measurements were reliable either with samples of 10 or 20 beats. Bland Altman method demonstrated the reliability of measurements. Finally, all measurements were comparable to published in vivo data. Conclusion: The presented mock circulation was reliable and gave values with high accuracy both at baseline and during mechanical assistance. This system allows evaluation of the mesenteric flow during IABP, under different clinical/hemodynamic conditions. Nonetheless, its translational potential needs to be further evaluated

The Influence of Red Cell Mechanical Properties on Flow Through Single Capillary-Sized Pores

1988 ◽  
Vol 110 (2) ◽  
pp. 155-160 ◽  
Author(s):  
R. S. Frank ◽  
R. M. Hochmuth
Keyword(s):  
Mechanical Properties ◽  
Transit Time ◽  
Shear Viscosity ◽  
Fold Increase ◽  
Red Cell ◽  
Geometric Properties ◽  
Transit Times ◽  
Percent Increase ◽  
Flow Through ◽  
In Transit

The resistive pulse technique was used to study the influence of specific mechanical properties of the red cell on its ability to enter and flow through single capillary-sized pores with diameters of 3.6, 5.0 and 6.3 μm and lengths of 11 μm. A two-fold increase in membrane shear elasticity resulted in a 40 percent increase in the cell’s transit time through a 3.6 μm pore but produced no change in transit time through a 6.3 μm pore. A two-fold increase in membrane shear viscosity produced a 40 percent increase in transit time through the 3.6 μm pore and small but significant increases in transit times through the larger pores. Osmotically dehydrated cells showed no increase in transit time through a 6.3 μm pore, but showed increases in transit times of 50 to 70 percent through 5.0 and 3.6 μm pores. Dense red cells showed increased transit times through both 5.0 μm and 6.0 μm pores. These results indicate that for cells with normal geometric properties, the membrane’s shear viscosity and elasticity only influence the cell’s transit through pores of 5 μm or less in diameter. However, alterations in the cell’s geometric properties can extend the influence of membrane shear properties to larger diameter pores.

scholarly journals An Evaluation of the Drone Delivery of Adrenaline Auto-Injectors for Anaphylaxis: Pharmacists’ Perceptions, Acceptance, and Concerns

Drones ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 66
Author(s):  
September Beck ◽  
Tam T. Bui ◽  
Andrew Davies ◽  
Patrick Courtney ◽  
Alex Brown ◽  
...  
Keyword(s):  
Threatening Condition ◽  
Life Threatening ◽  
Relevant Group ◽  
Chemical Purity ◽  
Vitro Model ◽  
The Stability ◽  
The Uk ◽  
Auto Injector ◽  
Temperature Storage

Anaphylaxis is a life-threatening condition where delays in medical treatment can be fatal. Such situations would benefit from the drone delivery of an adrenaline auto-injector such as EpiPen®. This study evaluates the potential risk, reward, and impact of drone transportation on the stability of adrenaline during episodes of anaphylaxis. Further, this study examines pharmacists’ perceptions on drone delivery—pharmacists approved the use of drones to deliver EpiPen® during emergencies but had concerns with drone safety and supply chain security. Laboratory simulated onboard drone conditions reflected typical missions. In these experiments, in vitro model and pharmaceutical equivalent formulations were subjected independently to 30 min vibrations at 5, 8.43, and 13.33 Hz, and temperature storage at 4, 25, 40, and 65 °C for 0, 0.5, 3, and 24 h. The chiral composition (an indicator of chemical purity that relates to molecular structure) and concentration of these adrenaline formulations were determined using ultraviolet (UV) and circular dichroism spectroscopy (CD). Adrenaline intrinsic stability was also explored by edge-of-failure experimentation to signpost the uppermost limits for safe transportation. During drone flight with EpiPen®, the temperature and vibration g-force were 10.7 °C and 1.8 g, respectively. No adverse impact on adrenaline was observed during drone flight and laboratory-simulated conditions shown by conformation to the British Pharmacopeia standards (p > 0.05 for CD and UV). This study showed that drone delivery of EpiPen® is feasible. There are more than 15,000 community pharmacies and ≈9000 GP surgeries spanning the UK, which are likely to provide achievable ranges and distances for the direct drone delivery of EpiPen®. The authors recommend that when designing future missions, in addition to medicine stability testing that models the stresses imposed by drone flight, one must conduct a perceptions survey on the relevant group of medical professionals, because their insights, acceptance, and concerns are extremely valuable for the design and evaluation of the mission.

A simple in vitro model to study the stability of acylglucuronides

2007 ◽  
Vol 55 (1) ◽  
pp. 91-95 ◽  
Author(s):  
Zhesheng Chen ◽  
Tom G. Holt ◽  
James V. Pivnichny ◽  
Kwan Leung
Keyword(s):  
In Vitro Model ◽  
Vitro Model ◽  
The Stability

scholarly journals Targeting Human Osteoarthritic Chondrocytes with Ligand Directed Bacteriophage-Based Particles

Viruses ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2343
Author(s):  
Aitthiphon Chongchai ◽  
Sajee Waramit ◽  
Tunchanok Wongwichai ◽  
Jirawan Kampangtip ◽  
Thanyaluck Phitak ◽  
...  
Keyword(s):  
Targeted Delivery ◽  
Articular Chondrocytes ◽  
Degenerative Joint Disease ◽  
Joint Disease ◽  
Cmv Promoter ◽  
Virus Serotype ◽  
Wide Range ◽  
Vitro Model ◽  
The Stability

Osteoarthritis (OA) is a degenerative joint disease characterized by progressive deterioration and loss of articular cartilage. There is currently no treatment to reverse the onset of OA. Thus, we developed a targeted delivery strategy to transfer genes into primary human chondrocytes as a proof-of-concept study. We displayed a chondrocyte-affinity peptide (CAP) on the pIII minor coat protein of the M13 filamentous bacteriophage (phage)-based particle carrying a mammalian transgene cassette under cytomegalovirus CMV promoter and inverted terminal repeats (ITRs) cis elements of adeno-associated virus serotype 2 (AAV-2). Primary human articular chondrocytes (HACs) were used as an in vitro model, and the selectivity and binding properties of the CAP ligand in relation to the pathogenic conditions of HACs were characterized. We found that the CAP ligand is highly selective toward pathogenic HACs. Furthermore, the stability, cytotoxicity, and gene delivery efficacy of the CAP-displaying phage (CAP.Phage) were evaluated. We found that the phage particle is stable under a wide range of temperatures and pH values, while showing no cytotoxicity to HACs. Importantly, the CAP.Phage particle, carrying a secreted luciferase (Lucia) reporter gene, efficiently and selectively delivered transgene expression to HACs. In summary, it was found that the CAP ligand preferably binds to pathogenic chondrocytes, and the CAP.Phage particle successfully targets and delivers transgene to HACs.

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