Combined chemotherapy of experimental infection in neutropenia

A significant decrease in resistance to infections caused by gramnegative pathogens was observed in mice with neutropenia induced by cytostatics. Efficacy of schemes for combined chemotherapy with beta-lactams, aminoglycosides and a novel peptide antibiotic was studied on model infections in mice with neutropenia. In the neutropenic mice with sepsis caused by Pseudomonas the peptide antibiotic administered parenterally in a single dose of 50 micrograms/kg provided high therapeutic activity. In combination with azlocillin, cefotaxime and amikacin the peptide antibiotic has a synergistic therapeutic action.     

Multiple xenobiotic-inducible P450s are involved in alkoxycoumarin and alkoxyresorufin metabolism in higher plants

O-Dealkylation of two series of fluorescent 7-alkoxy-coumarins and 7-alkoxyphenoxazones by plant cytochrome P450s was investigated in Helianthus tuberosus tuber tissues treated with prototype P450 inducers, environmental pollutants or agrochemicals. Methoxy-, ethoxy-, propoxy-and butoxycoumarins and methoxy- and ethoxyresorufins were metabolized by fplant microsomes. Dealkylation of pentoxy- and benzyloxyresorufins was not detected. All dealkylating activities were enhanced by aging plant tissues in the presence of xenobiotics, in some cases up to 20-fold relative to the activities detected in control tissues. Increases in total P450 in the same tissues never exceeded 3-fold. The isozymes induced by prototype P450 inducers clearly differed from those in mammalian liver. That multiple P450s with overlapping substrate specificities were involved in the metabolism of both alkoxycoumarins and alkoxyresorufins was demonstrated by (1) the differential induction of the activities in response to exposure to xenobiotics, (2) the differential inhibition of the activities by clotrimazole, paclobutrazole and tetcyclacis in aminopyrine and benzo(a)pyrene-treated tissues, and(3) the selective inhibition observed with antibodies raised against purified ethoxycoumarin deethylase fractions. Our results suggest that the measurement of the dealkylation of such fluorescent substrates in plants might be useful to monitor environmental pollution.     

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

Biotypes of Agrobacterium tumefaciens in Hungary

Isolates of Agrobacterium tumefaciens from Hungary were separated into three biotypes on the basis of their physiological characters. Biotypes 1 and 2 corresponded with those of Keane et al . (1970). The most common isolates were of biotype 2. Isolates from grapevines formed a separate biotype which might be distinguished from biotype 1 by D-(–)tartrate and malonate utilization. Many isolates with biotype-intermediate characters were found. Isolates utilizing D-(–)tartrate, erythritol and malonate were included into biotype 2, although many of them were 3–ketolactose positive. Biotypes were not separated geographically and biotype 1 and 2 apparently occurred together.     

Accumulation and metabolism of aldicarb by the free-living nematodes Aphelenchus avenae and Panagrellus redivivus

The accumulation and metabolism of aldicarb has been compared in two species of free-living soil nematodes, Aphelenchus avenae and Panagrellus redivivus, which differ considerably in their sensitivity to this and other pesticides. Similar levels of aldicarb were found to accumulate in the two species. The results showed that although the rate of uptake of aldicarb was greater in P. redivivus, so also was the rate of metabolism and elimination. Levels of toxic metabolites of aldicarb were two to three times higher in the more susceptible species A. avenae after 24 h incubation than in the less susceptible P. redivivus. The toxicological significance of these findings is discussed in relation to previous work with the organophosphorus pesticide phorate and its effects on the same two nematode species.     

Hematopoietic stem cells in mice during embryonic development preceding the establishment of liver hematopoiesis]

We studied the time course of appearance of CFUs (7-8 days old) in embryos of (C57B1/6 x CBA)F1 mice from the 8th day of embryonic development. Significant amounts of CFUs could be detected from the 10th day of development, initially in the body of the embryo from the stage of 30-33 pairs of somites, then in the yolk sac and still later, from the stage of about 40 pairs of somites, in liver anlage. CFUs could not be reliably detected until the 9th day of development either in the embryo itself or in the yolk sac. However, after incubation of nine day old embryos for four days in organ culture, such cultures contained CFUs. CFUs could be found in significant levels in embryos explanted from the embryos at the stage no earlier than 24 pairs of somites. When the yolk sac and the embryo were cultivated separately, CFUs could also be detected, however, the removal of liver primordium from the embryo did not influence the amount of CFUs in its body. CFUs were not found in cultures of liver primordium from nine day old embryos. Thus, we can detect pre-CFUs in 9 day old embryos at the stage 25-28 pairs of somites using the system of organ culture; at the same time CFUs cannot be found in intact embryos of the same age. These data provide evidence that before the establishment of liver hemopoiesis precursors of CFUs are located both in the yolk sac and in the embryo outside rudimentary liver. However, our results do not provide any data for the conclusion about the primary source of pre-CFUs in the mouse embryo.