Recognition of 29 kDa surface-associated adhesive molecule of Entamoeba histolytica by monoclonal antibodies

Abstract Monoclonal antibodies have been developed and used as specific probe to locate and identify a 29-kDa molecule of axenic Entamoeba histolytica trophozoites. Monoclonal antibody produced by clone C8 (MoAb C8) strongly agglutinated the amoebic trophozoites. THe immunofluorescence of live E. histolytica trophozoites and surface fluorescence of acetone-fixed trophozoites by MoAb C8 indicated existence of a 29-kDa molecule on surface-associated plasma membrane of E. histolytica . The monoclonal antibody belonged to IgG₁ isotype. The prior treatment of E. histolytica trophozoites with MoAb C8 resulted in significant ( P < 0.01) reduction in adherence of amoebic trophozoites to cultured Chinese Hamster Ovary cells and significant ( P < 0.01) reduction in cytotoxicity to cultured Baby Hamster Kidney cells. Pretreatment of amoebic trophozoites with MoAb C8 prior to cultivation in TPS-1 medium resulted in significant ( P < 0.01) reduction in growth of the parasite. Thus, the data suggested that the surface-exposed 29-kDa molecule may be one of the receptors involved in E. histolytica host cell interactions and may possibly modulate amoebic disease processes.     

The Effects of Severe Hypobaric Hypoxia and Inhibition of Hypoxia-Inducible Factor-1 (HIF-1) on Biomarkers of Cardiac and Skeletal Muscle Injury in Rats

Biophysics - Abstract—The goal of the present study was to investigate the molecular mechanisms that underlie heart and skeletal muscle damage in male Wistar rats weighing 200–250 g in...     

Photogeneration of NADH under coupled action of CdS semiconductor and hydrogenase from Alcaligenes eutrophus without exogenous mediators.

Photoreduction of NAD has been accomplished by a system consisting of the NAD-dependent hydrogenase from Alcaligenes eutrophus immobilized on CdS particles with formate as artificial electron donor. Enzymatically active NADH is formed under illumination of this system by visible light. Accumulation of the coenzyme dimer (NAD)2 was not detected. NAD photoreduction is supposed to proceed via the direct electron transfer from the semiconductor to the enzyme electron transport chain. However, NADH formation as a result of hydrogenase interaction with anion-radicals (CO2.-) formed in the course of formate photooxidation cannot at present be excluded.     

Some components of the air spora in Jamaica and their possible medical application

A knowledge of the pollen and fungal spores which comprise the air spora is useful as a preliminary approach to the problem of respiratory allergy. Therefore, this study of the qualitative and quantitative aspects of the air spora was done. Fungal spores were found to be numerically dominant, comprising 97.73% whilst pollen comprised 0.40% of the total material observed. A small number of types made up the majority of the fungal air spora, namely, Cladosporium, the Sporobolomycetaceae group, Diatrype, Glomerella, hyaline and coloured basidiospores, and septate fusiform spores. Seasonal periodicity studies on twenty-five fungal types showed that a high number of spores were trapped for sixteen during wet months, four during cooler months, and that five showed no seasonal trends. Mean diurnal periodicity studies for the year on the same twenty-five spore types showed that all had a maximum number of spores trapped at some time during the day. Investigation of the effect of rainfall on the numbers of spores released showed that the amount and duration of rainfall, the time of day rain occurs, and the length of the dry period preceding rain were of varying importance to particular spore types.     

Interspecific agonistic behaviour in small mammals in a Mexican high-elevational grassland

Field trials were conducted throughout an annual cycle to study the role of agonistic behaviour in explaining the relative abundance of the volcano mouse ( Neotomodon alstoni ) in a small mammal community in high-altitude grasslands of central Mexico. Intrasexual contests between N. alstoni and three other sympatric rodents ( Peromyscus melanotis, Microtus mexicanus, and Reithrodontomys megalotis ) were performed. Male and female P. melanotis (100 and 67% of contests, respectively) and M. mexicanus (82 and 100%) were aggressively dominant over N. alstoni , whereas R. megalotis (80 and 100%) were not aggressive. Agonistic behaviour in this species did not explain its greater abundance in the community.     

Effects of vitamins A, E, C and P on intensity of blood coagulation in experimental animals]

In experiment on white rats it was shown that preventive 12-day administration of vitamins A, E, C, P decreases the death rate of animals with exogenous thromboplastinemia and reduces hemocoagulative changes, microcirculation disorders, destructive changes of functionally active elements of inner organs. The protective effect of the above vitamins combination in thromboplastinemia is promoted by hypoactivity of platelet aggregation, by low thromboplastic activity of erythrocytes, by limited destruction of vascular endothelium.     

Construction of isogenic gonococci with variable porin structure: effects on susceptibility to human serum and antibiotics

Protein I (PI) is the most abundant protein on the gonococcal cell surface and besides its porin function it may have important properties contributing to pathogenicity. By allelic exchange using cloned PI genes from FA19 (PIA) and MS11 (PIB) and a selectable marker introduced closely downstream of these genes, we constructed sets of isogenic gonococcal strains that differ only in their PI gene. Analysis revealed that PI has a major effect on stable resistance to normal human serum, and a slight effect on low-level resistance to antibiotics. All PIA/B hybrids were hypersusceptible to serum, suggesting a possible explanation for why such hybrids do not occur in nature.     

Effects of taurine and dipeptide Tyr-Tyr on ventricular defibrillation]

Results of the study of taurine and dipeptide Tyr-Tyr effect on the threshold values of functional lesions of the myocardium and heart defibrillation are reported. The experiments were carried out on 27 narcotized mongrel dogs weighing 12-30 kg. Defibrillation was performed using Lifepak-7 defibrillator (USA). Lesion threshold (LT), defibrillation threshold (DT) and electrotherapeutic index (ETI) as a LT:DT ratio were determined. In 14 experiments (control group) these parameters were evaluated during 3 h. In group 1 (6 experiments) taurine (100 mg/kg) was infused intravenously by the end of the 1st hour, in group 2--Tyr-Tyr (25 mg/kg). It was shown that infusion of taurine did not have a noticeable effect of the LT, DT and ETI values. Infusion of Tyr-Tyr resulted in an increase in LT and DT. The possibility to use dipeptide Tyr-Tyr in the complex of measures aimed at ceasing ventricular fibrillation is discussed.     

Lack of species specificity in the action of immunosuppressive factors of tumor cells and absence of competition between them and recombinant interleukin-2 and phytohemagglutinin for lymphocyte membrane receptors

We studied some possible mechanisms of action of immunosuppressor factors (ISF) produced by tumor cells on lymphocyte proliferation. ISF of murine tumor cell lines inhibited the mitogen induced proliferation of murine splenocytes as well as human mononuclear blood cells. Normal human mononuclear blood cells or concanavalin A-activated murine spleen cells preincubated with phytohemagglutinin (PHA) or interleukin 2 (IL-2) respectively, were strongly suppressed by ISF in response to these activators. When preincubated with splenocytes or blood cells for 2 h at 4 degrees C following washing, ISF suppressed the lymphocyte proliferation as effectively as when being with cells during all period of cultivation. ISF inhibited mitogen-induced lymphocyte proliferation at low dilutions. There was no competition for lymphocyte membrane receptors between these functionally heterogenic kinds of ISF. Collectively, these results show that ISF acted when being attached to some lymphocyte membrane receptors.