Taye, M. | bioRxiv Science

bioRxiv2023

The dynamics of whole blood and blood cells during a routine clinical laboratory test

Centrifugation is a commonly performed laboratory procedure that helps to separate blood cells such as red blood cells RBCs, white bood cells WBCs, and platelets from plasma or serum. Although centrifugation is a routine procedure in most medical laboratories, factors that affect the efficacy of the centrifugation process have never been studied analytically. In this paper, we examine the effect of centrifugation time on the efficacy of the centrifugation process by studying the dynamics of blood cells via the well-known Langevin equation or equivalently, by solving the Fokker-Plank equation. Our result depicts that the speed of the centrifuge is one of the determinant factors concerning the efficacy of the centrifugation process. As angular speed increases, centrifugal force increases and as a result, the particles are forced to separate from plasma or serum. The room temperature also considerably affects the dynamics of the sample during centrifugation. Most importantly, the generation of heat during centrifugation increases the temperature within a centrifuge, and as a result, not only the stability of the sample but also the mobility of analyse is affected. We show that as the temperature within the centrifuge intensifies, the velocity of the cells as well as the displacement of the cells in the fluid increases. We then study the dynamics of the whole blood during capillary action where in this case the blood flows upward in a narrow space without the assistance of external forces. Previous investigations show that the height that the fluid rises increases as surface tension steps up. The viscosity of the fluid also affects the capillary action but to date, the dependence of the height on viscosity has never been explored due to the lack of a mathematical correlation between the viscosity of blood and surface tension [1]. In this work, we first examine the correlation between surface tension and viscous friction via data fitting. Our result exhibits that the viscosity of the blood increases linearly as surface tension increases. The mathematical relation between the height and viscous friction is derived. It is shown that the height of the blood that rises in the capillary increases as the viscous friction intensifies. As the temperature of the room steps up, the height also decreases. The dependence of erythrocytes sedimentation rate on surface tension is also studied. The results obtained in this work show that the erythrocyte sedimentation rate ESR increases as surface tension steps down. PACS numbersValid PACS appear here

biophysics↗

bioRxiv2020

The correlation between antiviral drug, immune response and HIV viral load

Developing antiviral drugs is an exigent task since viruses mutate to overcome the effect of antiviral drugs. As a result, the efficacy of most antiviral drugs is short-lived. To include this effect, we modify the Neumann and Dahari model. Considering the fact that the efficacy of the antiviral drug varies in time, the differential equations introduced in the previous model systems are rewritten to study the correlation between the viral load and antiviral drug. The effect of antiviral drug that either prevents infection or stops the production of a virus is explored. First, the efficacy of the drug is considered to decreases monotonously as time progresses. In this case, our result depicts that when the efficacy of the drug is low, the viral load decreases and increases back in time revealing the effect of the antiviral drugs is short-lived. On the other hand, for the antiviral drug with high efficacy, the viral load, as well as the number of infected cells, monotonously decreases while the number of uninfected cells increases. The dependence of the critical drug efficacy on time is also explored. Moreover, the correlation between viral load, the antiviral drug, and CTL response is also explored. In this case, not only the dependence for the basic reproduction ratio on the model parameters is explored but also we analyze the critical drug efficacy as a function of time. We show that the term related to the basic reproduction ratio increases when the CTL response step up. A simple analytically solvable mathematical model is also presented to analyze the correlation between viral load and antiviral drugs.

biophysics↗