Mid-IR to near-IR image conversion by thermally induced optical switching in vanadium dioxide

We demonstrate the image conversion from mid-IR to near-IR (NIR) exploiting high-contrast optical switching in vanadium oxide thin-film layers. The intensity distribution of a mid-IR beam is converted to NIR wavelengths exploiting the strong reflectivity changes induced by optical pumping in the mid-IR. We show an experimental setup in which the radiation of a Tm-doped fiber laser at 1940 microm and a carbon dioxide at 10.6 microm has been converted to both 850 nm and 1064 nm. The resolution was 35 microm and was reached by using an inexpensive CCD camera. The sensitivity of the device increases linearly with sample temperature. We measured a threshold of 144 mW/cm(2), with a sample temperature of 62 degrees C.

Differential dose adjustments of immunosuppressants after resuming boosted versus unboosted HIV-protease inhibitors postliver transplant

Pharmacokinetic (PK) interactions between protease inhibitors (PI(s)) and immunosuppressive agents (IS) are critical elements in the management of HIV-infected patients who undergo liver transplantation (LT(x)). The primary objective of this study was to evaluate the decreases in IS dosages necessary to maintain an appropriate therapeutic window (TW) after initiating PI-based antiretroviral therapy regimens post-LT(x). Single-center, PK cross-sectional study of consecutive HIV-infected adult patients who underwent LT(x) was done. Blood trough concentrations (C(t)) of IS were obtained using a commercial MEIA test; plasma C(t) of PI(s) were measured using HPLC. Twelve consecutive HIV-infected adult patients (11 males, 1 female) were enrolled. More rapid increases in IS plasma C(t) were observed 48 h after initiating ritonavir (RTV)-boosted PI therapy post-LT(x) than when using unboosted PI(s). Seven patients developed acute renal failure. The median fold decrease in IS dosages required to regain IS concentrations that were in the TW was 7.5 (range 6-14) after resuming boosted PI(s) and 2.9 (range 2-4) after unboosted PI(s). The overall median time necessary to reach IS TW after dose adjustment was 3.5 days (range 0-15). Unboosted PI(s) exhibited lesser PK interactions with IS than did RTV-boosted PI(s) and were thus more amenable to use in the post-LT(x) setting.

Efficacy and safety of atazanavir in patients with end-stage liver disease

BACKGROUND

No data are available on the use of atazanavir (ATV) in patients with end-stage liver disease (ESLD), and guidelines discourage its use in this setting. The objective of our study was to evaluate the efficacy and safety of unboosted ATV in patients infected with HIV and suffering from ESLD who had been screened for orthotopic liver transplantation (OLT(x)).

PATIENTS AND METHODS

This was a single-arm, 24-week pilot study. Atazanavir-naïve patients undergoing a highly active antiretroviral therapy were switched to ATV 400 mg daily plus two non-thymidine nucleoside reverse transcriptase inhibitors.

RESULTS

Fifteen patients (ten males and five females, age range 36-59 years) were enrolled in the study. Of these, 11 (73%) had a baseline CD4 cell count > 200 microl(-1), and 12 had undetectable plasma HIV-RNA. 12 subjects (80%) were able to remain on ATV until week 24 (n = 10) or transplantation (n = 2). At the end of the study, the median CD4 cell count was 340 microl(-1) , and nine of the ten patients had undetectable RNA. During the study period, two patients received a transplant, two died of intracerebral hemorrhage and lactic acidosis, respectively, and one discontinued ATV. Among the ten patients completing the 24-week study, no significant changes from baseline were observed for most of the liver function markers, with the exception of unconjugated bilirubin (from 1.15 mg/dl to 1.32 mg/dl, p = 0.047).

CONCLUSIONS

Unboosted ATV treatment did not worsen liver disease and was able to maintain or gain immunovirological eligibility for OLT(x) in all patients, with a limited effect on unconjugated bilirubin. These results suggest that ATV is an easy-to-use drug in patients with ESLD.

Sub-two-cycle light pulses at 1.6 microm from an optical parametric amplifier

We generate ultrabroadband pulses, spanning the 1200-2100 nm wavelength range, from an 800 nm pumped optical parametric amplifier (OPA) working at degeneracy. We compress the microjoule-level energy pulses to nearly transform-limited 8.5 fs duration by an adaptive system employing a deformable mirror. To our knowledge, these are the shortest light pulses generated at 1.6 microm.

The use of trough ribavirin concentration to predict sustained virological response and haematological toxicity in HIV/HCV-co-infected patients treated with ribavirin and pegylated interferon

OBJECTIVES

To study the association between trough ribavirin concentration (C(trough)) with sustained virological response (SVR) and haemoglobin (Hb) decrease in HIV/hepatitis C virus (HCV)-co-infected (HIV+/HCV+) patients treated with anti-HCV therapy.

METHODS

HIV+/HCV+ patients treated with ribavirin and pegylated interferon were prospectively evaluated. Qualitative and quantitative HCV-RNA, Hb levels and ribavirin C(trough) were measured at baseline and weeks 2, 4, 12, 24, 36 and 48 during therapy. HCV-RNA was also measured at 24 weeks after the end of therapy. Efficacy analysis was performed on patients with a definitive virological outcome (SVR, relapser and non-responder), whereas for toxicity analysis, dropouts were considered until the last available observation.

RESULTS

Fifty-two patients (54.7% with genotype 1 or 4) were included. Overall, no correlation between ribavirin C(trough) and early virological response (EVR) nor SVR was found. However, in patients with genotype 1 or 4, ribavirin C(trough) was independently associated with EVR (P = 0.036) and SVR (P = 0.046). A ribavirin C(trough) cut-off of 1600 ng/mL was found to be associated with both EVR (chi(2) = 5.69, P = 0.028) and SVR (chi(2)=4.2, P = 0.04). Higher ribavirin C(trough) correlated with Hb decrease (R = -0.361, P = 0.009) and was independently associated with an Hb decrease of >4 g/dL (P = 0.009). Receiver operating characteristic (ROC) analysis indicated that a ribavirin C(trough) of >2300 ng/mL was associated with an Hb decrease of >4 g/dL (chi(2) = 8.08, P = 0.01).

CONCLUSIONS

Our study confirmed a relationship between ribavirin exposure and both efficacy and toxicity. Moreover, we found ribavirin C(trough) cut-offs for both SVR in genotypes 1 and 4 and overall haematological toxicity. These findings deserve further clinical evaluation.

Antiretroviral activity of pegylated interferon alfa-2a in patients co-infected with HIV/hepatitis C virus

OBJECTIVES

To evaluate the early anti-HIV activity of pegylated interferon (PEG-IFN) alfa-2a and ribavirin in HIV/hepatitis C virus (HCV) co-infected patients not receiving antiretroviral therapy.

PATIENTS AND METHODS

In 19 patients with baseline plasma HIV load (HIV-RNA) >1000 copies/mL treated with PEG-IFN alfa-2a and ribavirin, HIV-RNA and T-cell subsets were measured at baseline and 2, 4 and 12 weeks after initiation of anti-HCV therapy.

RESULTS

We observed a significant HIV-RNA decrease (>1 log(10) copies/mL) through week 12 of anti-HCV treatment. The magnitude of HIV-RNA decline was associated with baseline HIV-RNA, CD4 count and PEG-IFN weight-adjusted dose.

CONCLUSIONS

A significant early anti-HIV activity of PEG-IFN alfa-2a was observed. Such an effect warrants further clinical evaluation in the management of co-infected patients.

Pharmacokinetic interaction between Amprenavir/Ritonavir and FosAmprenavir on cyclosporine in two patients with human immunodeficiency virus infection undergoing orthotopic liver transplantation

The pharmacokinetic interaction between highly active antiretroviral therapy (HAART) and immunosuppressive drugs is a critical element in the management of patients with human immunodeficiency virus infection who undergo orthotopic liver transplantation (OLT). We describe the effect of the coadministration of Amprenavir/Ritonavir (APV/r) and FosAmprenavir (FosAPV) on cyclosporine (CsA) concentrations in two patients receiving OLT for end-stage liver disease due to hepatitis C Virus. Patient 1, who was maintained on 300 mg CsA twice a day with a trough concentration (C(trough)) around 250 ng/mL, restarted HAART 12 days after transplantation with 300 mg APV/r twice a day with corresponding APV C(trough) of 5293 ng/mL and RTV C(trough) of 186 ng/mL. Forty-eight hours after initiation of HAART, C(trough) of CsA was 1200 mg/mL, so it was necessary to reduce the CsA dosage 12-fold (50 mg every day) to achieve a therapeutic effect. In Patient 2, who was maintained on 300 mg CsA twice a day and a corresponding C(trough) of 400 ng/mL, HAART was restarted 12 days post-OLT with FosAPV 1400 mg twice a day. After 48 hours C(trough) of CsA was around 600 ng/mL and C(trough) of FosAPV, 1221 ng/mL. In this case it was necessary to reduce the CsA administration 3.5-fold (175 mg every day). In conclusion, therapeutic drug monitoring was necessary to monitor HAART and CsA post-OLT to prevent toxicity due to both therapies. The use of FosAPV without ritonavir boostering is sufficient to maintain adequate CsA blood concentrations, avoiding any event of toxicity.

[Clinical pharmacology of nucleoside and nucleotide reverse transcriptase inhibitors]

Options for antiretroviral therapy in patients infected with HIV continue to expand as new drugs are integrated into treatment regimens. Nucleoside/nucleotide reverse transcriptase inhibitors (Nt/NRTIs) remain the backbone of highly active antiretroviral therapy (HAART). Although this is the oldest class of antiretrovirals, pharmacokinetic and pharmacodynamic properties have been less studied as compare to protease inhibotors (PIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs). The aim of this article is to review the current status of clinical pharmacology onf Nt/NRTIs, highlighting the issues with clinical interest. Therefore, implications of intracellular pharmacokinetics on dosing schedule, potential for drug-drug interaction and pharmacodynamics is discussed.

Gratings in a conical diffraction mounting for an extreme-ultraviolet time-delay-compensated monochromator

The conical diffraction mounting in which the direction of incident light belongs to a plane parallel to the direction of the grooves has the unique property of maintaining high diffraction efficiency, even in the extreme-ultraviolet (EUV) region. This property is useful for designing high-throughput time-delay-compensated monochromators for the spectral selection of ultrashort EUV pulses as the high-order harmonics generated by the interaction between an ultrashort laser pulse and a gas jet. The time compensation allows one to exploit the femtosecond scale duration of the harmonics both to have high intensity and to reach an unprecedented temporal resolution for pump and probe experiments. Because two gratings have to be used for time compensation, the high diffraction efficiency becomes an essential requirement, which can be fulfilled by the conical diffraction mounting. Measurements recently accomplished at the Bending Magnet for Emission Absorption and Reflectivity (BEAR) beam line (ELETTRA Synchrotron, Trieste, Italy) for three gratings in the 10-90 nm region are reported here that show a peak efficiency of as much as 0.7 in the first order. A model computing the electromagnetic propagation and the grating efficiency, implemented and tested with the experimental data, permits the study and design of rather complex systems operating in the conical mounting. Basic physical principles and mathematical aspects of the model are discussed here.

Key questions in antiretroviral therapy: Italian Consensus Workshop (2005)

A panel of leading Italian specialists in infectious diseases, virologists and immunologists met in Rome in 2005 to review critical data and discuss recommendations for each of the key questions in antiretroviral therapy today: When to start treatment? How to start? When to switch? What to switch to? Whether to stop or not to stop treatment, and how? The method of a nominal group meeting was used and recommendations were graded for their strength and quality using a system based on the one adopted by the Infectious Diseases Society of America. Main conclusions are summarized and critically discussed in this consensus statement, as well as some of the most recent data supporting these recommendations are provided.

Penetration of didanosine in semen of HIV-1-infected men

OBJECTIVES

The disposition of antiretroviral agents into genital tissue and fluids is one of the factors implicated in the control of viral replication within the male genital tract and should be an objective of highly active antiretroviral therapy. We have investigated didanosine penetration in seminal plasma of 16 HIV-infected patients.

PATIENTS AND METHODS

A total of 16 patients on didanosine (200 mg every 12 h or 400 mg once daily) participated in the pharmacokinetic study. After the didanosine morning dose, peripheral blood plasma and semen plasma were collected within the intervals 0-4, 4-8 and 8-12 h in the twice-daily regimen and 0-4, 4-12 and 12-24 h in the once-daily regimen.

RESULTS

Within each sampling time interval didanosine concentrations in seminal plasma were higher than in blood. The interquartile range of concentrations in seminal plasma was 292-1217 ng/mL, compared with 50-150 ng/mL in blood plasma. Didanosine could be detected in 14 of the 16 semen samples analysed and in 8 of the 16 blood samples.

CONCLUSIONS

We have demonstrated that didanosine penetrates into the seminal plasma in higher concentrations than in blood plasma.