A study of low-energy guest phonon modes in clathrate-II Na(x)Si136 (x = 3, 23, and 24).

Single-crystal x-ray diffraction from clathrate-II Na(x)Si(136) (x = 24) prepared by a new technique reveals the exceptionally large Na@Si(28) atomic displacement parameter (U(eq)) is strongly temperature dependent, and can be attributed to low-energy rattling modes associated with the Na guest. Inelastic neutron scattering (INS) spectra collected from Na(x)Si(136) powder specimens (x = 3, 23) confirm the presence of low-energy guest-derived phonon modes for Na@Si(28) and Na@Si(20). The lower energy Na@Si(28) rattler mode falls in the frequency range of the silicon host acoustic phonons, indicating the possibility for interaction with these phonons. The presence of these low-energy modes combined with the ability to controllably vary the guest content presents a unique opportunity for exploring the influence of guest-framework interactions on the lattice dynamics in intermetallic clathrates.

[Renal function aspects in carriers of the human immunodeficiency virus]. / Aspectos da função renal em portadores do vírus da imunodeficiência humana.

The occurrence of alterations was verified in some parameters of the asymptomatic individuals' renal function infected by the virus of the human immunodeficiency (HIV). Forty seven individuals were studied, taking place renal functional tests, as: creatinine clearance, clearance of free water, clearance osmolar, reabsorption tubular proximal and distal of sodium and potassium and urinary pH. The results revealed significant differences (p < 0.05) in the urinary pH, larger in the group with HIV (6.36 +/- 0.41), that in the controls (6.02 +/- 0.41); in the clearance of free water, that indicated reabsorption of larger water in the group with HIV (1.00 +/- 0.64 ml/min) and in the clearance osmolar, that was 2.00 +/- 0.83 ml/min in the group with HIV and 1.57 +/- 0.48 ml/min. The remaining of the indicators of renal function was not shown statistically different between an and other group. It was ended that those differences are significant, in spite of the absolute values they be inside of the normality, because could be associated to late evolutionary alterations of the disease, such as the increase of the frequency of infections of the urinary treatment and the dilution hyponatremia. More studies are necessary for if they confirm those hypotheses.

Aspectos da função renal em portadores do vírus da imunodeficiência humana / Renal function aspects in carriers of the human immunodeficiency virus

Verificou-se a ocorrência de alterações em alguns parâmetros da função renal de indivíduos infectados pelo virus da imunodeficiência humana (HIV), assintomáticos. Foram estudados 47 indivíduos, realizando-se provas funcionais renais: depuração de creatinina endógena, depuração de água livre, depuração osmolar, reabsorção tubular proximal e distal de sódio, excreção fracional de sódio e potássio e pH urinário. Os resultados revelaram diferenças significantes (p < 0,05) no pH urinário, maior no grupo HIV (6,36 ± 0,41), do que nos controles (6,02 ± 0,41); na depuração de água livre, que indicou reabsorção de água maior no grupo HIV (1,00 ± 0,64ml/min), do que nos controles (0,53 ± 0,48ml/min) e na depuração osmolar, que foi 2,00 ± 0,83ml/min no grupo HIV e 1,57 ± 0,48ml/min nos controles. O restante dos indicadores de função renal estudados não se mostraram diferentes estatisticamente entre um e outro grupo. Concluiu-se que essas diferenças são significativas, apesar de os valores absolutos estarem dentro da normalidade, pois podem estar associadas a alterações evolutivas tardias da doença, tais como o aumento na frequência de infecções do trato urinário e a hiponatremia dilucional. Mais estudos são necessários para se confirmarem essas hipóteses.

The occurrence of alterations was verified in some parameters of the asymptomatic individuals' renal function infected by the virus of the human immunodeficiency (HIV). Forty seven individuals were studied, taking place renal functional tests, as: creatinine clearance, clearance of free water, clearance osmolar, reabsorption tubular proximal and distal of sodium and potassium and urinary pH. The results revealed significant differences (p < 0.05) in the urinary pH, larger in the group with HIV (6.36 +/- 0.41), that in the controls (6.02 +/- 0.41); in the clearance of free water, that indicated reabsorption of larger water in the group with HIV (1.00 +/- 0.64 ml/min) and in the clearance osmolar, that was 2.00 +/- 0.83 ml/min in the group with HIV and 1.57 +/- 0.48 ml/min. The remaining of the indicators of renal function was not shown statistically different between an and other group. It was ended that those differences are significant, in spite of the absolute values they be inside of the normality, because could be associated to late evolutionary alterations of the disease, such as the increase of the frequency of infections of the urinary treatment and the dilution hyponatremia. More studies are necessary for if they confirm those hypotheses.

Comparison of Ritonavir in a First Choice Three Drug Regimen, After Two Nucleoside Analogues and in Saquinavir Experienced Patients.

Ritonavir is a potent, orally bioavailable inhibitor of HIV-1 protease. Our investigators undertook a retrospective study to compare the effectiveness of ritonavir (600mg twice daily) associated with 2 reverse transcriptase inhibitors (RTIs) in 38 patients in 3 situations. Group I patients previously treated with 2 RTIs, Group II treatment-naive patients, and Group III patients previously treated with 2 RTIs and saquinavir. Routine hematological and biochemical studies, HIV-1 viremia, and CD4+ lymphocyte counts were performed before and after ritonavir. In Group I, the median of HIV-1 RNA plasma levels decreased from 4.8 to 3.4 log(10) copies/mL, in Group II from 5.9 to 2.9 log(10) copies/mL, and in Group III from 5.2 to 4.1 log(10) copies/mL. (p=0.003, p=0.014, p=0.002, respectively, Wilcoxon signed rank test). The median increases of CD4(+) cells occurred as follows: in Group I from 173 to 282 cells/mm(3), in Group II from 92 to 254 cell/mm(3), and in Group III from 68 to 133 cell/mm(3) (p=0.002, p=0.008, p<0.001, respectively, Wilcoxon signed rank test). In Group II the mean weight increased from 55.2 +/-14.3 kg to 59.4+/-15.7 kg and, in Group III, from 62.2+/-10.5 kg to 67.5+/-12 kg (p = 0.026, p = 0.002, respectively, paired T test). Patients in Group I presented no weight gain. Mild reversible hypertriglyceridemia occurred in 6 of 38 patients. The results of this study showed that ritonavir is a good choice for treatment naive patients and as a sequential option, not only after 2 RTIs, but also after a 3 drug regimen with saquinavir.