Ontogenetic profile of ecto-5′-nucleotidase in rat brain synaptic plasma membranes

Ecto-5′-nucleotidase (CD73; EC 3.1.3.5, e-5NT) is regarded as the key enzyme in the extracellular formation of adenosine, which acts as a neuromodulator and important trophic and homeostatic factor in the brain. In the present study, we have investigated e-5NT activity, kinetic properties concerning AMP hydrolysis and the enzyme protein abundance in the purified synaptic plasma membrane (SPM) preparations isolated from whole female rat brain at different ages. We observed pronounced increase in AMP hydrolyzing activity in SPM during maturation, with greatest increment between juvenile (15-day-old) and pre-pubertal (30-day-old) rats. Immunodetection of e-5NT protein in the SPM displayed the reverse pattern of expression, with the maximum relative abundance at juvenile and minimum relative abundance in the adult stage. Negative correlation between the enzyme activity and the enzyme protein abundance in the SPM indicates that e-5NT has additional roles in the synaptic compartment during postnatal brain development, other than those related to AMP hydrolysis. Determination of kinetic parameters, K_m and V_max, suggested that the increase in the enzyme activity with maturation was entirely due to the increase in the enzyme catalytic efficiency (V_max/K_m). Finally, double immunofluorescence staining against e-5NT and presynaptic membrane marker syntaxin provided first direct evidence for the existence of this ecto-enzyme in the presynaptic compartment. The results of the study suggest that e-5NT may be a part of general scheme of brain development and synapse maturation and provide rationale for the previously reported inconsistencies between enzyme immunohistochemical and biochemical studies concerning localization of e-5NT in the brain.     

Vertical force and torque analysis during mechanical preparation of extracted teeth using hand ProTaper instruments

The purpose was to measure and analyse the vertical force and torque developed in the wider and narrower root canals during hand ProTaper instrumentation. Twenty human incisors were divided in two groups. Upper incisors were experimental model for the wide, while the lower incisors for the narrow root canals. Measurements of the force and torque were done by a device constructed for this purpose. Differences between the groups were statistically analysed by Mann-Whitney U-test with the significance level set to P<0.05. Vertical force in the upper incisors ranged 0.25-2.58 N, while in the lower incisors 0.38-6.94 N. Measured torque in the upper incisors ranged 0.53-12.03 Nmm, while in the lower incisor ranged 0.94-10.0 Nmm. Vertical force and torque were higher in the root canals of smaller diameter. The increase in the contact surface results in increase of the vertical force and torque as well in both narrower and wider root canals.     

Late Presentation to Care for HIV Infection in Croatia and the Effect of Interventions During the Croatian Global Fund Project

There are limited data on how HIV prevention interventions affect individuals presenting to care in settings with a low-level HIV epidemic. We examined whether interventions undertaken during the Croatian Global Fund Project in 2004–2006 had an influence on patients entering care. The number of men who have sex with men (MSM) presenting in 2004–2006 (n = 86) was 59% higher than in 2001–2003 (n = 54); in heterosexual patients the increase was 14% (n = 51 in 2001–2003; n = 58 in 2004–2006). MSM presented at a younger age (median 32 years) in 2004–2006 than in 2001–2003 (median 36 years). Late presentation to care was found in 28% of MSM and in 59% of heterosexual patients in 2004–2006. MSM were less frequently late presenters in 2004–2006 compared with 2001–2003 (odds ratio, 0.48; 95% confidence interval, 0.24 to 0.99; P = 0.046). Additional strategies for earlier initiation of care must be developed for MSM and particularly for heterosexual patients.