INAUGURAL ARTICLE by a Recently Elected Academy Member:Characterization of a 34-kDa soybean binding protein for the syringolide elicitors

Syringolides are water-soluble, low-molecular-weight elicitors that trigger defense responses in soybean cultivars carrying the Rpg4 disease-resistance gene but not in rpg4 cultivars. ¹²⁵I-syringolide 1 previously was shown to bind to a soluble protein(s) in extracts from soybean leaves. A 34-kDa protein that accounted for ¹²⁵I-syringolide 1 binding activity was isolated with a syringolide affinity-gel column. Partial sequences of internal peptides of the 34-kDa protein were identical to P34, a previously described soybean seed allergen. In soybean seeds, P34 is processed from a 46-kDa precursor protein and was shown to have homology with thiol proteases. P34 is a moderately abundant protein in soybean seeds and cotyledons but its level in leaves is low. cDNAs encoding 46-, 34-, and 32-kDa forms of the soybean protein were cloned into the baculovirus vector, pVL1392, and expressed in insect cells. The resulting 32- and 34-kDa proteins, but not the 46-kDa protein, exhibited ligand-specific ¹²⁵I-syringolide binding activity. These results suggest that P34 may be the receptor that mediates syringolide signaling.     

Phototoxicity studies of pazufloxacin mesilate,a novel parenteral quinolone antimicrobial agent--in vitro and in vivo studies

Phototoxicity of pazufloxacin mesilate (PZFX mesilate), a novel parenteral quinolone antimicrobial agent, were evaluated in vitro and in vivo studies. In vitro, phototoxicity for cultured cells of PZFX, which is active principle of PZFX mesilate, was studied, and stability for long-wavelength ultraviolet (UVA) was examined. In vivo, phototoxicity tests in guinea pigs and rats, and photoallergenicity tests in guinea pigs were conducted. In the phototoxicity test on cultured cells, CHL/IU cells were irradiated UVA of 300-3000 mJ/cm2 in the presence of PZFX, ofloxacin (OFLX), lomefloxacin (LFLX) or sparfloxacin (SPFX) at 10 micrograms/mL. Phototoxic potencies for cultured cells of the quinolones tested were SPFX > LFLX > OFLX > PZFX. In addition, changes in ultraviolet absorption spectrum and residual rate of PZFX, OFLX, LFLX and SPFX were examined after UVA irradiation of 300-3000 mJ/cm2 to each solution. PZFX was stable for UVA compared with OFLX and LFLX. In the phototoxicity test of guinea pigs, each quinolone was administered intraperitoneally daily for 7 days, and UVA of about 11 J/cm2 was irradiated at 30 minutes after the last administration. Dose levels of each quinolone were 65 and 130 mg/kg of PZFX mesilate (dose levels converted to PZFX: 50 and 100 mg/kg), 50 and 100 mg/kg of nalidixic acid (NA), 100 mg/kg of OFLX, enoxacin (ENX), ciprofloxacin (CPFX), LFLX and SPFX. Grade of skin reaction (erythema) at 24 hours after UVA irradiation decreased in the order: SPFX > CPFX > NA > ENX = OFLX > LFLX > PZFX mesilate. Thus, PZFX mesilate was found to have the weakest phototoxicity. In the maximum plasma concentration of quinolones from 0.5 to 2.5 hours after administration, corresponding to the time of UVA irradiation, the concentration of the group administered PZFX mesilate was about 4.1 times higher than that of CPFX group, and about 1.3 times higher than that of SPFX group. The area under the blood concentration-time curve (AUC0.5-2.5) of the group administered PZFX mesilate was the same as that of SPFX group, and about 3.2 times larger than that of CPFX group. These data showed that phototoxicity of PZFX mesilate was also weaker than that of CPFX or SPFX in consideration of AUC0.5-2.5. In the phototoxicity test of rats injected intravenously, no phototoxicity was observed at 130 mg/kg of PZFX mesilate. In the photoallergenicity test of guinea pigs, no photoallergenicity was observed by PZFX mesilate. As mentioned above, from in vitro studies PZFX was found to be stable for UVA irradiation compared with OFLX and LFLX, and phototoxicity for cultured cells of PZFX was weaker than that of SPFX, LFLX or OFLX. In addition, from in vivo studies phototoxicity of PZFX mesilate was found to be weaker than that of NA, OFLX, ENX, CPFX, LFLX or SPFX, and no photoallergenicity was observed. Therefore, photosensitive potency of PZFX mesilate might be less than that of other quinolones.     

Newly diagnosed acute aortic dissection: characteristics, treatment modifications, and outcomes

The objective of the present study was to examine cases of acute aortic dissection in order to analyze the clinical and diagnostic findings, and to summarize their treatment modalities, as well as their hospital outcomes. Between July 1998 and June 1999, we prospectively studied patients who were newly diagnosed as having acute aortic dissection at 25 hospitals in Mie prefecture. These cases were examined for their demographics, the characteristics of the clinical findings, diagnostic methods, treatment modalities according to the type of aortic dissection, and the early morbidity and mortality of the hospital outcomes. Of 66 newly diagnosed aortic dissections (43 males), 30 were type A and 36 were type B. Seventy-six percent of the cases arrived at a medical facility within 6 hours from the onset of symptoms. Frequent initial symptoms and clinical findings were pain in 95.5%, cardiac arrest and/or hypotension in 21%, pericardial effusion in 29%, pleural effusion in 25%, and neurological signs in 30%. Twenty-one patients underwent surgical repair, 36 were treated medically, and 5 underwent endovascular stenting. Overall early mortality was 12.1%, which included 2 DOA. Fifty percent of these deaths occurred within 48 hours, and 63% by 72 hours of the initial event. In spite of the relatively rare incidence of acute aortic dissection in our study, the calculated incidence was 4.0/100,000/year. The overall mortality rate was relatively low compared to the figures reported in the literature, suggesting the earliest possible diagnosis and timely intervention are critically important to attain successful outcomes.     

Intravascular hemolysis in aortic stenosis

A 67-year-old woman with rheumatic aortic stenosis for 20 years was admitted to our hospital. Although she had no overt symptoms, she had severe aortic valve stenosis with a transvalvular pressure gradient of more than 150 mmHg. She had also been suffering from anemia and mild chronic renal failure. A peripheral blood smear showed numerous fragmented erythrocytes. Hemoglobin was 8.4 g/dl, lactate dehydrogenase was 316 IU/l, haptoglobin was less than 7.3 mg/dl, and hemosiderinuria was evident. We diagnosed intravascular hemolysis related to aortic stenosis. After we performed an aortic valve replacement, fragmentation on the peripheral blood smear dramatically disappeared.     

Attenuation of arbekacin-induced nephrotoxicity in rats by pazufloxacin mesilate

The protective effect of pazufloxacin (PZFX) mesilate, a parenteral quinolone antimicrobial agent, on arbekacin (ABK)-induced nephrotoxicity was evaluated with 8-week-old male Sprague-Dawley rats. Animals were injected with ABK at a dose of 32 mg/kg intramuscularly, or a combination of ABK in the same manner with PZFX mesilate at a dose of 208 mg/kg (160 mg/kg convert to PZFX, active principle of PZFX mesilate) intravenously once a day for 4 days. In consequent, ABK induced increases in protein, beta 2-microglobulin and N-acetyl-beta-(D)-glucosaminidase in urine, and histopathological phospholipidosis in kidneys. The extent of these changes was reduced when ABK was given in a combination with PZFX mesilate. Renal cortex level of ABK increased after an administration of ABK 1 hour to 4 hours; however, the increase was suppressed by coadministration of PZFX mesilate. Taken together, these results suggest that PZFX mesilate has the protective effect on ABK-induced nephrotoxicity, and that this was attributable to a suppression of uptake of ABK in cortical renal tubules.