Average real variability of 24-h systolic blood pressure is associated with microalbuminuria in patients with primary hypertension.

Limited and conflicting data are available about the association between short-term blood pressure (BP) variability and urinary albumin excretion rate (uAER). The objective of our study was to analyze the relationships between microalbuminuria (MAU), defined as an uAER between 20 and 200 µg min(-1), and short-term BP variability (BPV), assessed as average real variability (ARV), weighted s.d. of 24-h BP and as s.d. of daytime and night-time BP. The study population consisted of 315 untreated essential hypertensives with normal estimated glomerular filtration rate (>60 ml min(-1) per 1.73 m(2)), who underwent 24-h ambulatory BP monitoring and 24-h uAER determination. MAU was detected in 82 (26%) patients. ARV of 24-h systolic BP (SBP) was significantly higher in patients with MAU (9.8 (8.5-11.1) mm Hg) when compared with those without it (9.1 (8-10.2) mm Hg; P=0.007). This difference held (P=0.026) after adjustment for age, mean levels of BP and other potential confounders by analysis of covariance. A statistically significant correlation was also found between ARV of 24-h SBP and uAER (r=0.17; P=0.003). This association remained significant (ß=0.15; P=0.01), also taking into account the effect of 24-h average systolic and diastolic BP, age, gender, diabetes, serum uric acid, triglycerides, estimated glomerular filtration rate in multiple regression analyses. All the other indices of short-term BPV tested were not independently associated with MAU. Our results seem to suggest that in essential hypertension, short-term BPV, only when estimated by ARV of 24-h SBP, is independently associated with MAU.

Rapidly converging numerical algorithms for models of population dynamics.

We propose algorithms for the approximation of the age distributions of populations modeled by the McKendrick-von Foerster and the Gurtin-MacCamy systems both in one- and two-sex versions. For the one-sex model methods of second and fourth order are proposed. For the two-sex model a second order method is described. In each case the convergence is demonstrated. Several numerical examples are given.

An AIDS model with distributed incubation and variable infectiousness: applications to i.v. drug users in Latium, Italy.

An AIDS model with distributed incubation and variable infectiousness is considered and simulated via a second-order numerical method. The method is applied to the HIV epidemic among IV drug users in the Latium region of Italy, using available data on the length of the incubation period before the onset of AIDS, on the infectivity of infected individuals during that period, and on the demography of drug users. The contact rate is adjusted to match the actual number of AIDS cases. The sensitivity of the model to uncertainties in the parameters is finally investigated, by performing several simulations.