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Biomedical subjects

H PINKERTON

Publications and source records attributed to H PINKERTON.

At least 19 recordsLinked to original sources
PubMed1960

The effects of x-rays and beta rays (tritium) on the growth of Rickettsia mooseri and Rickettsia akari in embrvonate eggs.

The growth of Rickettsia mooseri was accelerated and quantitatively increased in embryonate eggs containing tritium oxide at levels of 180, 90, and 45 mc./egg during the growth period. The eggs of a group containing 22.5 mc./egg showed only a slight increase in the rate of growth of organisms; the infections in the eggs of a group given 11.2 mc./egg did not differ significantly from those of the control group. On the other hand, growth of R. akari was inhibited in embryonate eggs containing tritium oxide at levels of 180, 90, and 45 mc./egg, and partially inhibited in groups containing 22.5 and 11.2 mc./egg. The patterns of growth of R. mooseri and of R. akari exposed to tritium oxide for 6 hours prior to inoculation into embryonate eggs did not differ significantly from that of the control group. Single and divided doses of x-rays to the host resulted in partial inhibition of the growth of R. akari.

Beta Particles↗
PubMed1957

Further studies on the effects of x-radiation on the multiplication of Rickettsia mooseri in embryonate eggs.

The effect of x-rays on the growth of rickettsiae in the embryonate egg was investigated. The intensifying effect of x-radiation of the host on rickettsial growth can be attributed to alterations of the cells of the host that persist at least 7 days. The greatest enhancement of the growth of rickettsiae occurred when moderately infected cells were irradiated. These experiments indicate that x-rays may neutralize or reverse changes in the host that are unfavorable to the growth of rickettsiae. Explanations of the observed phenomena in terms of biochemical and biological alterations of the cells of the host are discussed.

Rickettsia↗
PubMed1957

The effect of x-rays on the rickettsiostatic activity of streptomycin, aureomycin, and penicillin.

The effect of x-rays on the rickettsiostatic activity of streptomycin, penicillin and aureomycin in the embryonate egg was investigated. Only a slight reversal of the rickettsiostatic action of 5 mg. of streptomycin occurred in embryonate eggs given 100 r of x-rays at 4 days of incubation, whereas complete reversal occurred in those given 1000 r. Groups of eggs irradiated with intermediate doses of x-rays showed a graded response. The rickettsiostatic activity of 5 mg. (1660 Oxford units/mg.) of penicillin or of 5 mg. of aureomycin was not reversed by doses of x-rays ranging from 100 to 1000 r. 500 r of x-rays reversed the rickettsiostatic activity of 2 mg., 4 mg., 8 mg., or 16 mg. of streptomycin per egg in proportion to the amount of streptomycin injected. The rickettsiostatic activity of 2 mg. of streptomycin was completely reversed and the activity of 16 mg. only partially reversed. Reversal of the rickettsiostatic activity of streptomycin by x-rays was observed when radiation was given up to 6 days after the injection of the antibiotic into 7-day-old embryos. Reversal of the rickettsiostatic activity of 4 mg. of streptomycin could be detected when the antibiotic was injected 3 days after 500 r of x-radiation. Explanations of the observed phenomena are discussed in terms of biochemical and biophysical alterations of the cells of the host.

Anti-Bacterial Agents↗
PubMed1954

The effects on biological materials of freezing and drying by vacuum sublimation. I. Development and testing of apparatus.

A vacuum sublimation apparatus is described which will permit, (a) the removal of water from virus suspensions at temperatures ranging down to -80 degrees C., (b) continuous operation with a minimum of attention from the investigator, (c) sealing off of samples at operating pressures (10(-5) mm. Hg), (d) simultaneous lyophilization of aliquot samples at different temperatures, (e) isolation of a portion of the apparatus without disturbing the remainder of the system, and (f) determination of the end-point of sublimation without disturbing the samples. The time required for drying 0.1 ml. of influenza virus suspension was shown to increase markedly with decrease of temperature, 8 days being required for dehydration at -80 degrees C. in contrast to 2 days at -30 degrees C. and 1 day at 0 degrees C.

Cold Temperature↗
PubMed1954

The effects on biological materials of freezing and drying by vacuum sublimation. II. Effect on influenza virus.

The infectivity titre of influenza virus-infected allantoic fluid was determined after a variety of procedures involving cyclic slow freezing and thawing, freezing at various rates with subsequent storage at different temperatures freezing at various rates with subsequent dehydration at various temperatures, and different degrees of dehydration. All these factors were found to influence the survival rate of the virus particles. Five freeze-thaw cycles resulted in a fall in titre from 10(-8.6) to 10(-0.8) cycles 2, 3, and 4 causing much greater losses than cycles 1 and 5. Rapid cooling to -40 degrees C. or slow cooling to -80 or 190 degrees C. did not cause significant titre loss, but rapid cooling to temperatures above -40 degrees or slow cooling to temperatures above -80 degrees C. caused definite titre loss. Loss of titre on storage occurred only at temperatures above -40deg;C. The effect of lyophilization depends both on the preliminary treatment and on the dehydration temperature. Better conservation of titre was obtained after preliminary cooling to -190 or -80 degrees C. than after preliminary cooling to higher temperatures. The most effective sublimation temperatures were 0 and -80 degrees .; the least effective was +20 degrees C. Titre losses in suspensions sublimated at -10, -30, and -60 degrees C. were in general intermediate. No loss in titre occurred after preliminary cooling to -80 or -190 degrees C. and subsequent dehydration at -80 or 0 degrees C. The degree of dehydration definitely affects the survival of virus on storage at 0 degrees C., but sublimation for 4 hours at 0 degrees C. gave complete protection against titre loss on storage at this temperature. Possible explanations of the observations made are suggested, based on known physiochemical phenomena such as supercooling, vitrification, variations in size and shape of ice crystals with different freezing speeds, differential enzyme inactivation, changes in salt concentration, and changes in energy levels.

Animals↗
PubMed1953

The effect of x-radiation on the oxygen uptake of embryonate eggs.

Groups of 10 day old embryonate eggs were given 250, 500, 750, and 1000 r of x-radiation, and oxygen consumption determinations were made subsequently at various intervals during a period of 90 hours. In general, the effect of radiation was moderately stimulatory, but after 90 hours the respiratory rates of the 250 and 1000 r groups were well below those of the control groups. The most striking effect, noted in 3 separate experiments, was the occurrence of a "3 step staircase" type of oxygen consumption curve in all irradiated groups, the levelling off periods apparently occurring between the 4th and 14th, the 24th and 36th, and the 42nd and 66th hours after exposure. These curves were in striking contrast to those shown by groups of non-irradiated eggs, which were practically of the straight line type.

Metabolism↗
PubMed1953

The effect of x-radiation on the multiplication of influenza A virus in embryonate eggs.

Groups of embryonate eggs were given 250, 500, 750, and 1000 r of x-radiation. 18 hours later, these 4 groups, together with a control group, were injected intra-allantoically with influenza A virus. Radiation at all dosage levels caused significant changes in the infectivity titre curves during the next 90 hours. The most striking alterations were the prolonged incubation period and the uniformly low infectivity titre in the group of eggs given 750 r.

Influenza A virus↗
PubMed1953

The effect of x-radiation on the multiplication of Rickettsia mooseri in embryonate eggs.

The multiplication of Rickettsia mooseri in fertile eggs is speeded up and quantitatively increased by single dose x-radiation given either 24 hours before or 48 hours after inoculation. This effect is noted at all dosage levels studied, ranging from 100 to 1500 r. The rickettsiostatic effects of high incubation temperature (40 degrees C.) and of streptomycin are neutralized by radiation, but the rickettsiostatic actions of PABA, penicillin, and aureomycin are not altered. Possible mechanisms of action and implications of the observed effects are discussed.

Rickettsia typhi↗