The frequency of neurological manifestations was evaluated in 653 HIV infected patients admitted in a university hospital in Rio de Janeiro city, Brazil, in the 1985-1989 period. A total of 172 (26%) patients developed neurological symptoms. Central nervous system complications included: cerebral toxoplasmosis (80), cryptococcal meningitis (57), subacute encephalitis (17), tuberculosis (8) and aseptic meningitis (2), progressive multifocal leukoencephalopathy (2) and vacuolar myelopathy (6). Peripheral neuropathy occurred in three cases. The clinical and tomographic aspects were analysed. The majority of the patients died within six months after the onset of the neurological disease.
Silver nanoparticles (AgNPs) have wide-ranging applications, including as additives in consumer products and in medical diagnostics and therapy. Therefore understanding how AgNPs interact with biological systems is important for ascertaining any potential health risks due to the likelihood of high levels of human exposure. Besides any severe, acute effects, it is desirable to understand more subtle interactions that could lead to milder, chronic health impacts. Nanoparticles are small enough to be able to enter biological cells and interfere with their internal biochemistry. The initial contact between nanoparticle and cell is at the plasma membrane. To gain fundamental mechanistic insight into AgNP-membrane interactions, we investigate these phenomena in minimal model systems using a wide-range of biophysical approaches applied to lipid vesicles. We find a strong dependence on the medium composition, where colloidally stable AgNPs in a glucose buffer have negligible effect on the membrane. However, at a physiological salt concentrations, the AgNPs start to weakly aggregate and sporadic but significant membrane perturbation events are observed. Under these latter conditions, transient poration and structural remodelling of some vesicle membranes is observed. We observe that the fluidity of giant vesicle membranes universally decreases by an average of 16% across all vesicles. However, we observe a small population of vesicles display a significant change in mechanical properties with lower bending rigidity and higher membrane tension. Therefore we argue that the isolated occurrences of membrane perturbation by AgNPs are due to low probability mechanosensing events of AgNP aggregation at the membrane.GRAPHICAL ABSTRACT
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