Leishmania tropica: studies on the mechanisms of attachment to and entry into macrophages

The in vitro attachment and entry of promastigotes of Leishmania tropica into mouse peritoneal macrophages were studied under defined experimental conditions. The attachment of promastigotes to macrophages was found to be dependent on temperature, macrophage intracellular metabolism, and the normal function of microfilaments and microtubules. Parasite binding was abolished by fixation of macrophages but not of the parasites. Modification of the surface of macrophages and parasites by various surface reactive agents revealed that surface carbohydrates of parasites and macrophages were important in parasite binding. Periodate and neuraminidase affected both parasites and macrophages in a complementary manner. Treatment of macrophages with trypsin and concanavalin-A also prevented parasite attachment. In the extracellular medium, parasite binding required the presence of magnesium, glucose and a macromolecular component of foetal calf serum and was inhibited by 2-deoxyglucose. The requirement for extracellular glucose could be replaced by mannose, suggesting that the requirement for glucose is structural rather than for purposes of energy metabolism. The active fraction of serum was nondialyzable, heat labile and precipitable by ammonium sulfate. The extracellular and surface structural requirements of parasite binding suggest the involvement of a biochemical process which is probably mediated by an enzymatic reaction. Scanning electron microscopic examination of macrophages infected with parasites revealed that motile promastigotes attached to host cells by their flagellar tips to which macrophages responded by producing closely fitting lamellar sheaths and progressively enveloping first the flagellum and then the body of the parasite. Lamellar advance during engulfment was rapid in the first lo minutes but much slower later on. Fully engulfed parasites could be seen after one hour, but most parasites associated with host cells remained extracellular even after four hours. On the other hand, parasites immobilized by fixation or heat shock adhered by either their flagellar or somatic ends. Engulfment proceeded at a steady rate and was complete by two hours. No clear distinction between the attachment and engulfment stages of parasite uptake could be established since both were inhibited by low-temperature, cytochalasin and mild fixation of macrophages. The rheological features of the host cells' response to parasite attachment indicate that invasion by parasites is through phagocytosis rather than penetration. surface structural requirements of parasite binding suggest the involvement of a biochemical process which is probably mediated by an enzymatic reaction. Scanning electron microscopic examination of macrophages infected with parasites revealed that motile promastigotes attached to host cells by their flagellar tips to which macrophages responded by producing closely fitting lamellar sheaths and progressively enveloping first the flagellum and then the body of the parasite. Lamellar advance during engulfment was rapid in the first 10 minutes but much slower later on. Fully engulfed parasites could be seen after one hour, but most parasites associated with host cells remained extracellular even after four hours. On the other hand, parasites immobilized by fixation or heat shock adhered by either their flagellar or somatic ends. Engulfment proceeded at a steady rate and was complete by two hours. No clear distinction between the attachment and engulfment stages of parasite uptake could be established since both were inhibited by low-temperature, cytochalasin and mild fixation of macrophages. The rheological features of the host cells' response to parasite attachment indicate that invasion by parasites is through phagocytosis rather than penetration

A lightweight sensing platform for monitoring sleep quality and posture: a simulated validation study

Background The prevalence of self-reported shoulder pain in the UK has been estimated at 16%. This has been linked with significant sleep disturbance. It is possible that this relationship is bidirectional, with both symptoms capable of causing the other. Within the field of sleep monitoring, there is a requirement for a mobile and unobtrusive device capable of monitoring sleep posture and quality. This study investigates the feasibility of a wearable sleep system (WSS) in accurately detecting sleeping posture and physical activity. Methods Sixteen healthy subjects were recruited and fitted with three wearable inertial sensors on the trunk and forearms. Ten participants were entered into a ‘Posture’ protocol; assuming a series of common sleeping postures in a simulated bedroom. Five participants completed an ‘Activity’ protocol, in which a triphasic simulated sleep was performed including awake, sleep and REM phases. A combined sleep posture and activity protocol was then conducted as a ‘Proof of Concept’ model. Data were used to train a posture detection algorithm, and added to activity to predict sleep phase. Classification accuracy of the WSS was measured during the simulations. Results The WSS was found to have an overall accuracy of 99.5% in detection of four major postures, and 92.5% in the detection of eight minor postures. Prediction of sleep phase using activity measurements was accurate in 97.3% of the simulations. The ability of the system to accurately detect both posture and activity enabled the design of a conceptual layout for a user-friendly tablet application. Conclusions The study presents a pervasive wearable sensor platform, which can accurately detect both sleeping posture and activity in non-specialised environments. The extent and accuracy of sleep metrics available advances the current state-of-the-art technology. This has potential diagnostic implications in musculoskeletal pathology and with the addition of alerts may provide therapeutic value in a range of areas including the prevention of pressure sores

Intuitionistic fuzzy set: feeg image representation

Flat Electroencephalography (fEEG) is a technique that mapped high dimensional signal into low dimensional space. An image of fEEG which is in grayscale is obtained via fuzzy approach by the process of digitization and quantization. In this paper, the enhancement of fEEG images of two epileptic patients at varied time are presented. The images are enhanced by using intuitionistic fuzzy set theory (IFS). Moreover, the quality test of the images is determined by mean structural similarity index measure (MSSIM) for particular values of parameter namely lambda, λ in the Sugeno type intuitionistic fuzzy generator. The relationship between the membership, non-membership, and hesitation degree for λ=2 and λ=5 (of patient A at t=1) are demonstrated graphically

The determination of hesitation value for sugeno type intuitionistic fuzzy generator via fuzzy limit

In intuitionistic fuzzy set (IFS) theory, the membership and non- membership values are needed to model the uncertainties. One of the ways to compute the non-membership is by implementing the Sugeno type intuitionistic fuzzy generator. In this paper, fuzzy limit will be used to determine the value of parameter, namely in the non-membership function. Different values of ? will directly control the level of hesitation, namely p, in the output image. Hence, the output images of Flat EEG (fEEG) during epileptic seizures are enhanced by using the window based enhancement scheme