Effect of high energy electrons on H⁻ production and destruction in a high current DC negative ion source for cyclotron.

Recently, a filament driven multi-cusp negative ion source has been developed for proton cyclotrons in medical applications. In this study, numerical modeling of the filament arc-discharge source plasma has been done with kinetic modeling of electrons in the ion source plasmas by the multi-cusp arc-discharge code and zero dimensional rate equations for hydrogen molecules and negative ions. In this paper, main focus is placed on the effects of the arc-discharge power on the electron energy distribution function and the resultant H(-) production. The modelling results reasonably explains the dependence of the H(-) extraction current on the arc-discharge power in the experiments.

High current DC negative ion source for cyclotron.

A filament driven multi-cusp negative ion source has been developed for proton cyclotrons in medical applications. In Cs-free operation, continuous H(-) beam of 10 mA and D(-) beam of 3.3 mA were obtained stably at an arc-discharge power of 3 kW and 2.4 kW, respectively. In Cs-seeded operation, H(-) beam current reached 22 mA at a lower arc power of 2.6 kW with less co-extracted electron current. The optimum gas flow rate, which gives the highest H(-) current, was 15 sccm in the Cs-free operation, while it decreased to 4 sccm in the Cs-seeded operation. The relationship between H(-) production and the design/operating parameters has been also investigated by a numerical study with KEIO-MARC code, which gives a reasonable explanation to the experimental results of the H(-) current dependence on the arc power.

A selective pulmonary thrombosis associated with sepsis-induced disseminated intravascular coagulation.

Disseminated intravascular coagulation (DIC) is a pathologic condition associated with critical illnesses, including sepsis. Recent studies have suggested that endogenous cytokines and leukocytes are involved in major roles of its pathophysiology. We report a case of sepsis-induced DIC due to pneumonia that was associated with diffuse and selective thrombosis in pulmonary arteries, yielding to sudden death from pulmonary massive embolism. This report suggests that the selective and lethal pulmonary thromboembolism progresses under the standard therapies in sepsis-induced DIC.

Active inhibitory effect of nafamostat mesylate against the elevation of plasma myeloperoxidase during hemodialysis.

Plasma levels of myeloperoxidase (MPO) were compared between hemodialysis (HD) sessions using heparin and those using nafamostat mesylate (NM) as an anticoagulant by an enzyme immunoassay established in our laboratory. MPO levels were markedly elevated during the entire HD procedure with heparin. In contrast, MPO levels were scarcely elevated during the HD with NM. On the other hand, polymorphonuclear leukocyte-elastase was markedly elevated during both of these HD procedures. These observations indicated that NM selectively attenuated MPO elevation in vivo during HD. This inhibitory effect of NM was further investigated ex vivo. Blood samples from a normal subject were collected with heparin alone, NM alone and a mixture of heparin and NM. Each sample was then circulated in a closed circuit composed of a dialyzer with a cuprophane membrane. MPO levels with heparin alone were shown to markedly rise in the closed system. In contrast, levels of MPO in the blood samples mixed with NM were not elevated even in the presence of heparin. These ex vivo results indicate that NM has an active inhibitory effect on the elevation of plasma MPO induced by granulocyte activation through a dialysis membrane. Our results demonstrate that clinical use of NM as an anticoagulant serves to selectively suppress MPO elevation considered as a consequence of granulocyte activation during HD.

Swine cerebrospinal angiopathy and demyelination and malacia.

In 15 pigs affected with cerebrospinal angiopathy accompanied by demyelination and malacia, the main symptoms were diarrhea and subsequent circling, spasms, sudden forward movements, ataxia, and inability to hold the head straight. Escherichia coli was isolated in a pure culture from the small intestine of pigs with diarrhea. The only gross change was a slight increase in cerebrospinal fluid. Histologic examination showed vascular lesions, demyelination, and malacia, most commonly located in the medulla oblongata, pons, and midbrain. The vascular lesions were degenerative and there were necrotic changes of the vessel walls and formation of periodic acid-Schiff positive perivascular eosinophilic droplets. Ultrastructurally, the swollen astrocytes around the vessels had many osmiophilic bodies in their cytoplasm with no limiting membrane. Demyelination and malacia, as well as vascular lesions, were considered to be the characteristic changes of cerebrospinal angiopathy. Our study suggests that E. coli may be a cause of cerebrospinal angiopathy.