scholarly journals Plasmodium falciparum: Assessment of Selectivity of Action of Chloroquine, Alchornea cordifolia, Ficus polita, and Other Drugs by a Tetrazolium-Based Colorimetric Assay

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Nana Kofi Ayisi ◽  
Regina Appiah-Opong ◽  
Ben Gyan ◽  
Kwasi Bugyei ◽  
Fred Ekuban
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Incubation Time ◽  
Blood Cells ◽  
Colorimetric Assay ◽  
In Vitro Assay ◽  
Effective Concentration ◽  
Vitro Assay ◽  
Number Of Cells

A tetrazolium-based colorimetric selective assay (MTT-based CSA) was developed to assess the selectivity of antimalarial drugs. This in vitro assay, unlike all others, measures the ability of drugs to indirectly protect red blood cells (RBCs) from Plasmodium-falciparum-induced destruction. Optimum incubation time and number of cells needed were 5 days and 23×106 RBCs per well, respectively. A parasitemia range of 0.375% to 3% was found to be suitable for this assay. The MTT-based CSA determined anti-P. falciparum strain DD2 activity of chloroquine at a higher 50% effective concentration (EC50) value (21.0 μg/mL) than the isotopic microtest (10.0 μg/mL). Artesunate and oxytetracycline achieved 90% effect against DD2 with minimal or no toxicity to RBCs. Against chloroquine sensitive strain 3D7, chloroquine and Alchornea cordifolia had EC50 values of 0.025 μg/mL and 4.9 μg/mL respectively, and selective index (SI) values of >2,000 and >69.4 μg/mL, respectively.

In Vitro Assay for Single-cell Characterization of Impaired Deformability in Red Blood Cells under Recurrent Episodes of Hypoxia

Lab on a Chip ◽  
2021 ◽  
Author(s):  
YUHAO QIANG ◽  
Jia Liu ◽  
Ming Dao ◽  
E Du
Keyword(s):  
Shear Stress ◽  
Red Blood Cells ◽  
Single Cell ◽  
Blood Cells ◽  
Blood Circulation ◽  
In Vitro Assay ◽  
Vitro Assay ◽  
Cyclic Shear

Red blood cells (RBCs) are subjected to recurrent changes in shear stress and oxygen tension during blood circulation. The cyclic shear stress has been identified as an important factor that...

scholarly journals A new in vitro assay for carbon dioxide excretion by trout red blood cells: effects of catecholamines

1991 ◽  
Vol 157 (1) ◽  
pp. 349-366 ◽  
Author(s):  
C. M. Wood ◽  
S. F. Perry
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Time Course ◽  
In Vitro Assay ◽  
Vitro Assay ◽  
Acid Base Status ◽  
Excretion Rates ◽  
Co2 Excretion

A new in vitro assay was developed and critically characterized to measure the rate of CO2 excretion by trout red blood cells (RBCs) from HCO3- in their natural plasma under normal in vivo conditions of acid-base status. The assay is based on the addition of [14C]bicarbonate to the whole blood and collection of the resultant 14CO2 in the overlying gas phase. The assay simulates the exposure of blood passing through the gills, and measured CO2 excretion rates are representative of those occurring in vivo. Rates are linear over the 3 min time course of the assay, related to haematocrit in a non-linear fashion, elevated by the addition of carbonic anhydrase, reduced by blockade with acetazolamide, and sensitive to variations of equilibration PCO2. Large variations in plasma [HCO3-] have only a small effect on CO2 excretion rates when the blood is chronically equilibrated at these levels. Acute elevations in [HCO3-], however, create a non-equilibrium situation, resulting in large increases in CO2 excretion. When the blood is acidified, to duplicate typical post-exercise metabolic acidosis, adrenaline causes a marked inhibition of RBC CO2 excretion. The response is transient, reaching a peak 5–8 min after addition of adrenaline and disappearing by 30–60 min. The magnitude of the adrenergic inhibition is correlated with the magnitude of the RBC pHi regulatory response, expressed as the RBC transmembrane pH difference (pHe-pHi). These results support the ‘CO2 retention theory’ explaining observed increases in blood PCO2 in vivo after exhaustive exercise and catecholamine infusions in fish.

Cinnamomum zeylanicum extract on the radiolabelling of blood constituents and the morphometry of red blood cells: In vitro assay

2008 ◽  
Vol 66 (2) ◽  
pp. 139-146 ◽  
Author(s):  
M.O. Benarroz ◽  
A.S. Fonseca ◽  
G.S. Rocha ◽  
J.N.G. Frydman ◽  
V.C. Rocha ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
In Vitro Assay ◽  
Cinnamomum Zeylanicum ◽  
Vitro Assay ◽  
Blood Constituents

Ultrastructural observations on the in vitro cytoadherence of Plasmodium falciparum infected red blood cells

1990 ◽  
Vol 48 (3) ◽  
pp. 914-915
Author(s):  
D.J.P. Ferguson ◽  
A.R. Berendt ◽  
J. Tansey ◽  
K. Marsh ◽  
C.I. Newbold
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Umbilical Vein ◽  
Cell Types ◽  
Amelanotic Melanoma ◽  
Cytoplasmic Process ◽  
Umbilical Vein Endothelial Cells

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

scholarly journals In Vitro Assessment of Antiplasmodial Activity and Cytotoxicity of Polyalthia longifolia Leaf Extracts on Plasmodium falciparum Strain NF54

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Bethel Kwansa-Bentum ◽  
Kojo Agyeman ◽  
Jeffrey Larbi-Akor ◽  
Claudia Anyigba ◽  
Regina Appiah-Opong
Keyword(s):  
Plasmodium Falciparum ◽  
Ethyl Acetate ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Radical Scavenging ◽  
Antimalarial Drugs ◽  
Antiplasmodial Activity ◽  
Leaf Extracts ◽  
Polyalthia Longifolia

Background. Malaria is one of the most important life-threatening infectious diseases in the tropics. In spite of the effectiveness of artemisinin-based combination therapy, reports on reduced sensitivity of the parasite to artemisinin in Cambodia and Thailand warrants screening for new potential antimalarial drugs for future use. Ghanaian herbalists claim that Polyalthia longifolia has antimalarial activity. Therefore, antiplasmodial activity, cytotoxic effects, and antioxidant and phytochemical properties of P. longifolia leaf extract were investigated in this study. Methodology/Principal Findings. Aqueous, 70% hydroethanolic and ethyl acetate leaf extracts were prepared using standard procedures. Antiplasmodial activity was assessed in vitro by using chloroquine-sensitive malaria parasite strain NF54. The SYBR® Green and tetrazolium-based calorimetric assays were used to measure parasite growth inhibition and cytotoxicity, respectively, after extract treatment. Total antioxidant activity was evaluated using a free radical scavenging assay. Results obtained showed that extracts protected red blood cells against Plasmodium falciparum mediated damage. Fifty percent inhibitory concentration (IC50) values were 24.0±1.08 μg/ml, 22.5±0.12 μg/ml, and 9.5±0.69 μg/ml for aqueous, hydroethanolic, and ethyl acetate extracts, respectively. Flavonoids, tannins, and saponins were present in the hydroethanolic extract, whereas only the latter was observed in the aqueous extract. Aqueous and hydroethanolic extracts showed stronger antioxidant activities compared to the ethyl acetate extract. Conclusions/Significance. The extracts of P. longifolia have antiplasmodial properties and low toxicities to human red blood cells. The extracts could be developed as useful alternatives to antimalarial drugs. These results support claims of the herbalists that decoctions of P. longifolia are useful antimalarial agents.

scholarly journals Identification of Proteins from Plasmodium falciparum That Are Homologous to Reticulocyte Binding Proteins inPlasmodium vivax

2001 ◽  
Vol 69 (2) ◽  
pp. 1084-1092 ◽  
Author(s):  
Tony Triglia ◽  
Jenny Thompson ◽  
Sonia R. Caruana ◽  
Mauro Delorenzi ◽  
Terry Speed ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Molecular Mass ◽  
Blood Cells ◽  
Potential Role ◽  
High Molecular Mass ◽  
In Vitro Growth ◽  
Merozoite Invasion ◽  
Genome Databases

ABSTRACT Plasmodium falciparum infections can be fatal, whileP. vivax infections usually are not. A possible factor involved in the greater virulence of P. falciparum is that this parasite grows in red blood cells (RBCs) of all maturities whereasP. vivax is restricted to growth in reticulocytes, which represent only approximately 1% of total RBCs in the periphery. Two proteins, expressed at the apical end of the invasive merozoite stage from P. vivax, have been implicated in the targeting of reticulocytes for invasion by this parasite. A search of the P. falciparum genome databases has identified genes that are homologous to the P. vivax rbp-1 and -2 genes. Two of these genes are virtually identical over a large region of the 5′ end but are highly divergent at the 3′ end. They encode high-molecular-mass proteins of >300 kDa that are expressed in late schizonts and localized to the apical end of the merozoite. To test a potential role in merozoite invasion of RBCs, we analyzed the ability of these proteins to bind to mature RBCs and reticulocytes. No binding to mature RBCs or cell preparations enriched for reticulocytes was detected. We identified a parasite clone that lacks the gene for one of these proteins, showing that the gene is not required for normal in vitro growth. Antibodies to these proteins can inhibit merozoite invasion of RBCs.

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