Junichi Hirayama

Reduction in adverse reactions to platelets by the removal of plasma supernatant and resuspension in a new additive solution (M-sol).

BACKGROUND: Leukodepletion reduces but does not eliminate adverse reactions to platelet concentrate (PC). As an alternative strategy, plasma reduction or washing of platelets should be considered. However, the efficacy of this strategy is still unclear.

Storage of platelets in a novel additive solution (M-sol), which is prepared by mixing solutions approved for clinical use that are not especially for platelet storage

BACKGROUND: To reduce adverse reactions due to platelet (PLT) transfusion, medical solutions on the market, such as saline and ACD‐A, are used to replace the plasma of PLT concentrates in Japan; however, they are not strongly preservative. Here, an attempt was made to develop a novel additive solution (M‐sol) having the ability to preserve PLTs stably, with only approved solutions for clinical use.

Photoinactivation of Virus Infectivity by Hypocrellin A

Abstract— We investigated the photoinactivation of virus infectivity by hypocrellin A and its mechanism. The titers of vesicular stomatitis virus (VSV) and human immunodeficiency virus type 1 (HIV‐1), both of which are enveloped viruses, were reduced upon illumination with hypocrellin A in a concentration‐dependent manner, whereas canine parvovirus, a nonenveloped virus, was not killed. The removal of oxygen or addition of sodium azide or bT‐carotene both inhibited VSV inactivation. Mannitol and superoxide dismutase had no effect on VSV inactivation. These results indicate that singlet oxygen was involved in the process of VSV inactivation. Of the three major VSV membrane proteins, peripheral membrane protein M was most damaged by the hypocrellin A phototreatment.

Flash photolysis study on pharaonis phoborhodopsin from a haloalkaliphilic bacterium (Natronobacterium pharaonis)

Abstract Pharaonis phoborhodopsin (ppR) functions as a photoreceptor of the negative phototaxis of haloalkaliphilic bacterium (Natronobacterium pharaonis). The absorbance maximum of ppR is located at 498 nm. ppR has a cyclic photo-reaction (photo cycle): upon illumination, ppR transforms to a photo-intermediate which returns to the original pigment through various intermediates in the dark reaction. By flash-photolysis in a millisecond time scale, the photocycle of ppR was investigated. Two photointermediates were found whose λmax was 390 nm and 550 nm. The former is referred to as ppRM, and the latter as ppRO since these correspond respectively to M- and O-intermediates of bacteriorhodopsin. Flash photolysis data were kinetically analyzed according to the cyclic sequential scheme of ppR → ppRM → ppRO → ppR. In the analysis of kinetic data of one wavelength representing the change in an intermediate, the contribution from other intermediates or the original pigment was considered because their absorption maxima are close to each other. The rate constant of ppRM → ppRO was taken as k1, and that of ppRO → ppR, k2. k1 depended greatly on pH in the medium, while k2 had little dependence on pH. The activation energies of k1 and k2 were determined. Addition of azide (100 mM, pH 7, 20°C) led to about 40-fold increase of k1 while the influence on k2 was slight.

Maintenance of platelet in vitro properties during 7-day storage in M-sol with a 30-hour interruption of agitation

BACKGROUND: Extensive periods without agitation can occasionally occur during platelet (PLT) shipment and can affect PLT quality during 5‐ to 7‐day storage. The use of buffer‐containing PLT additive solutions (ASs) may better preserve PLT quality during storage by maintaining PLT pH and other in vitro variables. A newly described bicarbonate‐containing AS, M‐sol, was compared to plasma for preservation of whole blood–derived PLT concentrates in which a 30‐hour interruption of agitation was included.

Inactivation of parvovirus B19 in coagulation factor concentrates by UVC radiation: assessment by an in vitro infectivity assay using CFU–E derived from peripheral blood CD34+ cells

BACKGROUND: Nonenveloped and thermostable viruses such as parvovirus B19 (B19) can be transmitted to patients who are receiving plasma‐derived coagulation factor concentrates treated by the S/D method for inactivating enveloped viruses. Therefore, it is important to develop and validate new methods for the inactivation of nonenveloped viruses.

Comparison between in vitro qualities of platelets washed with commercially available additive solutions and those washed with M-sol.

Background and Objectives  We previously developed a novel additive solution (M‐sol) with a high ability to preserve the in vitro qualities of platelets (PLTs) in washed PLTs Here, we compared the ability of M‐sol with that of commercially available additive solutions (ASs) to preserve the in vitro qualities (pH, mean PLT volume, %disc, P‐selectin, %hypotonic shock response and aggregation) of PLTs at a low plasma concentration.

Replaced platelet concentrates containing a new additive solution, M-sol: safety and efficacy for pediatric patients

Allergic transfusion reactions (ATRs), particularly those caused by plasma‐rich platelet concentrates (P‐PCs), are an important concern in transfusion medicine. Replacing P‐PCs with PCs containing M‐sol (M‐sol‐R‐PCs) is expected to prevent ATRs. However, this has not yet been verified by sufficient clinical evidence.

Virus inactivation in hemoglobin solution by heat treatment

To increase the safety of stroma-free hemoglobin solution (SFH) as an artificial oxygen carrier source, we investigated the effect of heat treatment on virus inactivation in hemoglobin solution. The hemoglobin solution spiked with vesicular stomatitis virus (VSV) was treated at 60°C for 1 hr under either an air or CO atmosphere. VSV was inactivated at >5.8 log10 and >6.0 log10 under the air and CO atmosphere, respectively. Although the methemoglobin rate increased after the heat treatment under the air atmosphere, no methemoglobin formation was observed by the treatment under the CO atmosphere. Isoelectric focusing analysis revealed the denaturation of hemoglobin after the heat treatment under the air, while hemoglobin banding was not altered in the carbonylated condition. Some protein bands other than hemoglobin were weakened or disappeared on SDS-PAGE after the heat treatment under both conditions. In addition, the hemoglobin concentration in the SFH was higher after the heat treatment than before the treatment. These findings indicate that the heat treatment under the CO atmosphere inactivates viruses without hemoglobin denaturation, and hence, this method is a promising approach to prepare a safer SFH as artificial oxygen carriers.

SHAPE OF THE CHROMOPHORE BINDING SITE IN PHARAONIS PHOBORHODOPSIN FROM A STUDY USING RETINAL ANALOGS

Abstract To investigate the shape of the chromophore binding site of pharaonis phoborhodopsin (ppR), ppR‐opsin was incubated with five ring‐modified retinal analogs: an acyclic retinal, phenylretinal, α‐retinal, cyclohexylretinal and 5‐isopropyl‐α‐retinal. The experimental results were compared with those obtained from bacteriorhodopsin‐opsin (bR‐opsin) and the same retinal analogs. It was suggested that ring chain conformation is important in affecting the spectral shoulder unique for the absorption spectrum of ppR. The rate of pigment formation depended greatly on the analogs used with the planar analogs showing rapid formation. Thus, we concluded that the space of the retinal binding site of ppR is restricted to the plane of the cyclohexenyl ring of the chromophore, whereas that of bR is less restricted.