Viral-specific immunization in AIDS-related complex by photopheresis

Chemically treated plasma Aβ is a potential blood-based biomarker for screening cerebral amyloid deposition

BACKGROUND

Plasma β-amyloid (Aβ) is a potential candidate for an Alzheimer's disease (AD) biomarker because blood is an easily accessible bio-fluid, which can be collected routinely, and Aβ is one of the major hallmarks of AD pathogenesis in the brain. However, the association between plasma Aβ levels and AD diagnosis is still unclear due to the instability and inaccurate measurements of plasma Aβ levels in the blood of patients with AD. If a consistent value of plasma Aβ from the blood can be obtained, this might help determine whether plasma Aβ is a potential biomarker for AD diagnosis.

METHODS

We predicted the brain amyloid deposit by measuring the plasma Aβ levels. This cross-sectional study included 353 participants (215 cognitively normal, 79 with mild cognitive impairment, and 59 with AD dementia) who underwent Pittsburgh-compound B positron emission tomography (PiB-PET) scans. We treated a mixture of protease inhibitors and phosphatase inhibitors (MPP) and detected plasma Aβ42 and Aβ40 (MPP-Aβ42 and MPP-Aβ40) in a stable manner using xMAP technology.

RESULTS

MPP-Aβ40 and MPP-Aβ42/40 (MPP-Aβs) were significantly different between subjects with positive amyloid deposition (PiB+) and those with negative amyloid deposition (PiB-) (P < 0.0001). Furthermore, MPP-Aβ40 (P < 0.0001, r = 0.23) and MPP-Aβ42/40 ratio (P < 0.0001, r = -0.23) showed significant correlation with global PiB deposition (standardized uptake value ratio). In addition, our integrated multivariable (MPP-Aβ42/40, gender, age, and apolipoprotein E genotypes) logistic regression model proposes a new standard for the prediction of cerebral amyloid deposition.

CONCLUSIONS

MPP-Aβ might be one of the potential blood biomarkers for the prediction of PiB-PET positivity in the brain.

Photodynamic inactivation of cell-free HIV strains by a red-absorbing chlorin-type photosensitizer

We have investigated the photodynamic activity of a new chlorin-type photosensitizer on a reference human immunodeficiency virus type 1 (HIV-1) strain, two wild-type HIV-1 isolates and two drug-resistant HIV-1 isolates. This chlorin was highly effective for the inactivation of free viruses, as assessed by two different quantitative cell culture assays. In the absence of blood components, all the HIV strains, including wild-type and drug-resistant mutant isolates, were totally inactivated using 30 micrograms ml-1 of chlorin and 0.75 J cm-2 of 661 nm light. Successful killing of HIV-1 strains in either plasma or whole blood was also obtained by increasing the chlorin concentration moderately. Our results demonstrate the antiviral efficiency of this chlorin, suggesting the potential application of dye-sensitized photoirradiation to decontaminate blood products.

Photobiological activity of sulphur and selenium analogues of psoralen

Eight psoralen analogues, in which sulphur or selenium replaces one or both intracyclic oxygen atoms, were synthesized. Photoreaction with M13mp19 RF DNA in the presence and absence of oxygen (wavelength, greater than 320 nm) was studied. The damaged viral DNA was transfected into Escherichia coli and scored for infectivity towards Ca-treated wild-type E. coli. This allowed a comparative evaluation to be made of the heteropsoralens in terms of the photoreaction with DNA and the photodynamic effect. Most of the seleno- and thio-psoralens show very high photoactivity towards DNA compared with psoralen and 8-methoxypsoralen (8-MOP). Their photoreactivity is due mainly to a [2 + 2] photoreaction, since only a minor influence of molecular oxygen could be detected. Some of the studied seleno- and thio-psoralens are very efficient DNA photoinactivating agents and show great promise in photochemotherapy.

Photosensitizers as virucidal agents

The photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA) has been studied regarding its ability to destroy enveloped viruses in blood and blood products when activated by light. Its maximum wavelength of absorption (690 nm) has proven useful in terms of activation of the photosensitizer in materials containing red blood cells. Experiments conducted on whole blood of patients infected with the human immunodeficiency virus (HIV) demonstrated that BPD-MA and light could effectively eliminate the virus when treated materials were placed in culture and tested for viral p24, but did not appear to damage blood cells or blood components. Since HIV is largely intracellular in infected individuals, these results were investigated further. We have shown, using flow cytometry, that in HIV-infected blood, BPD-MA and light appear to selectively destroy white cells that bear the interleukin 2 receptor and the DR antigen. These markers are prevalent on activated lymphocytes, and since HIV replicates only in CD4+ T cells which are activated, this finding provides an explanation for the selective killing of HIV.