A quantitative method to establish the clinical evolution of HIV infected patients and the reproductive biology of an echinoid species from Brazil

Abstract

AIDS is one of the several diseases that affect the human being. Vast amount of resources are being spent by governments to develop new drugs and therapies for the treatment of infected individuals with distinct results (e.g., Scherer et al. 2007). However, although several antiviral drugs have proved to successfully reduce the advance of the virus in the organism, they have also caused a series of undesired side effects. The most common of them are diarrhea and nausea that in several cases can severely reduce the quality of the patient's life.In order to understand the clinical evolution of HIV infected individuals, some mathematical models have been applied. In the present issue of the Anais da Academia Brasileira de Ciências (AABC), Juliana Grégio of the Instituto Tecnológico de Aeronáutica (ITA) and colleagues present a method that can be used to reduce the side effects while enhancing effectiveness of the drugs applied to HIV infected patients. The basis of this method is the optimal control theory, which is essentially a mathematical optimization method (e.g., Lewis 1986). As the authors point out, this quantitative method has been applied in a variety of fields such as economics, sociology and biology. In the present contribution, Grégio et al. (2009) discuss the problematic involving LQR (Linear Quadratic Regular) to establish the drug doses for extensive periods of treatment and advocate the use of Extended Kalman Filter for predicting the dosage of drugs in HIV infected patients in order to minimize the side effects. The authors carried out extensive simulations that have shown the possibility of decreasing drug doses and still maintaining the viral counts at a satisfactory level. As they pointed out, this quantitative method can help doctors to develop a better treatment strategy for their patients.Among the several other important papers published in the present volume of the AABC, one study provides relevant information regarding the reproduction strategy of a sea urchin (Echinoidea) from the northeastern part of Brazil. Sea urchins are important components of marine invertebrate faunas worldwide and an important food resource in some areas. Their long evolutionary history has been very useful in establishing paleoenvironments (e.g., Smith 1984) and their reproduction cycle is of great interest (e.g. Bosch et al. 1989).In some localities species of sea urchin have been regarded as responsible for the destruction of coral reefs. This impact is directly related with the amount of population present in a locality. Therefore, to evaluate the ecological interaction between rock-boring sea urchins and the reef, it is paramount to understand their life-history.

The Plastic Glial-Synaptic Dynamics within the Neuropil: A Self-Organizing System Composed of Polyelectrolytes in Phase Transition

“…The effects of exogenous potassium applied in retinas can be different from the ones shown in Figure 3 and reported previously for experiments with slow pulses [ 77 ]. If a very fast pulse of high concentration KCl (200 mEq/L and 200 µ L) is asperged with pipettes very close to the inner limiting membrane, then the local potential and optical response can behave as shown in Figure 4 .…”

“…What did not change in the record shown in Figure 3 was the abrupt rise of potassium and the potential drop when the front wave invaded the region sampled by the electrode. In 74 circling waves, the peaks of the simultaneously measured time derivative of potassium activity and potential drop coincided [ 77 ], suggesting tight coupling between the two wave concomitants, although there is no linear causality between them. In a different series, the simultaneously recorded time derivative of potential and of the µ IOS (the brightness of a 50 µ m square pixel matrix overlaying the electrode tip inserted in the inner plexiform layer) of retinal waves also showed coincidence between the extracellular potential drop and the change in the optical signal [ 17 ].…”

“…After a few seconds, potential and transparency were back to baseline values; however, the excess potassium made the system unstable and a wave was triggered 10 seconds after the pulse. The potassium rise at the inner plexiform layer at the wave onset coincides with the second component of the dV / dt time series [ 77 ]. The potential drops and the tissue transparency falls abruptly.…”