Intracellular calcium during photodynamic permeabilization of cardiomyocytes.

The purpose of this study was to determine whether an early increase in [Ca2+]i preceding generalized lysis of cardiomyocytes occurred during photodynamic permeabilization. A method was developed which facilitated the simultaneous measurement, in real time, of permeabilization of the sarcolemma to Ca2+ and Mn2+ during photodynamic action. Quin-2 loaded cells were illuminated in the presence of erythrosin B and the change in the fluorescence emission of the calcium-quin-2 complex was used to measure the rate and extent of change in [Ca2+]i. The same system was used in the presence of extracellular Mn2+ to determine how quickly the cardiomyocytes became permeable to either Mn2+ or quin-2. Calcium ions were observed to enter the myocytes prior to permeabilization of the sarcolemma to either Mn2+ or quin-2, and thus before membrane lysis. Lysis of cardiomyocytes did not appear to be dependent upon increases in [Ca2+]i. Controls were performed to rule out fluorescent artifacts. Reperfusion injury and photodynamic therapy involve both the production of free radicals and an early increase in [Ca2+]i. This study demonstrates a direct correlation between the production of reactive oxygen species and prelytic increases in [Ca2+]i in neonatal cardiomyocytes and demonstrates that this phenomenon may be common to many cell types.

Characterization of bacteriocins from two strains of Bacillus thermoleovorans, a thermophilic hydrocarbon-utilizing species.

Bacillus thermoleovorans S-II and B. thermoleovorans NR-9 produce bacteriocins, and these bacteriocins are designated thermoleovorin-S2 and thermoleovorin-N9, respectively. The bacteriocins are effective against all but the producing strain of B. thermoleovorans, as well as being effective against Salmonella typhimurium, Branhamella catarrhalis, Streptococcus faecalis, and Thermus aquaticus. Thermoleovorins are produced during log-phase growth and are inhibitory to actively growing cells. The bacteriocins are proteinaceous in nature, being sensitive to selected proteases (protease type XI and pepsin). They are stable at pHs of 3 to 10. Thermoleovorin-S2 was more thermostable than thermoleovorin-N9 at 70 and 80 degrees C. Thermoleovorins-S2 and -N9 apparently act by binding to the susceptible organisms, resulting in lysis of the cell. Thermoleovorins-S2 has an estimated M(r) of 42,000, while thermoleovorin-N9 has a M(r) of 36,000.

Effects of ozone treatment on the infectivity of hepatitis A virus.

The inactivation of a large-focus-forming variant of hepatitis A virus (HM-175) by ozone was investigated. Experiments using mainly single-particle virus preparations suspended in phosphate-carbonate buffer were conducted over a range of pH levels (6-8) at 4 degrees C. Viral enumerations involved the use of a radioimmunofocus assay. While some tolerance to lower (i.e., 0.1-0.5 mg/L) ozone residuals was noted, the exposure of virus particles to ozone concentrations of 1 mg/L or greater at all pH levels resulted in their complete (5 log) inactivation within 60 s. The pH-related effects that were observed were not considered to be significant.

Differentiation of four adenovirus types by macrophage migration inhibition tests.

The macrophage migration inhibition (MMI) test was found to be a satisfactory procedure for distinguishing between adenovirus types 1, 4, 5, and 7. Highly purified virus preparations were used for the sensitization of Hartley strain guinea pigs, whereas the MMI test antigen consisted of crude virus preparations grown in KB cells. With all four virus types, a significantly greater MMI response was noted when peritoneal exudate cells were exposed to the homologous sensitizing antigen as compared to that obtained with the three heterologous antigens. Studies with adenovirus type 1 indicate that sensitizing doses between 70 and 150 mug of viral protein per guinea pig gave the optimal MMI response. Doses below 70 mug did not stimulate the delayed response, whereas doses above 120 mug produced MMI reactions which were nonspecific, as differences between homologous and heterologous antigens were not demonstrable.

Pathogenesis and transmission of kilham rat virus infection in rats.

The Kilham rat virus (RV) was found to produce mortality in newborn rats after intracerebral, intravenous, or subcutaneous administration of virus. Both infectious virus and viral hemagglutinins were detected in a variety of tissues and in the blood and urine of experimentally infected rats. Contact control rats housed with infected littermates did not develop disease but did produce antibody to RV. Horizontal virus transmission was also evidenced by the seroconversion of antibody-negative mothers whose litters were infected with RV. The level of maternal antibody was found to be the determining factor in the susceptibility or refractiveness of newborn rats to RV infection. If the mother had no detectable hemagglutination-inhibiting (HI) antibody titer (less than 10) or a low antibody titer (10 or 20), her offspring were highly susceptible to RV. However, the litters of rats with HI titers of 40 or greater were afforded protection when challenged with RV; the higher the maternal antibody level the more solid was the protection conferred. Vertical transmission of RV was also demonstrated. Litters born of mothers infected with RV several days before delivery died within 7 to 9 days of a disease identical to that seen in infected newborns and virus was recovered from a variety of tissues. Results of mother-litter exchange experiments also indicated vertical transmission (rather than transmission through milk) occurs, since litters of infected mothers developed the disease when nursed by normal mothers, whereas litters of normal mothers remained normal although they were nursed by infected mothers.