Ability of various alkylating agents to induce adaptive and SOS responses: a study with lacZ fusion

We used alkA'-lacZ' and umuC'-lacZ' fused genes and determined the ability of various alkylating agents to induce adaptive and SOS responses. The degree of induction of expression of these genes was quantitatively measured by a simple colorimetric assay of beta-galactosidase activity. SN1 type methylating agents, such as N-methyl-N'-nitro-N-nitrosoguanidine and N-methyl-N-nitrosourea, were more effective inducers for the alkA than for the umuC system, while SN1 type ethylating agents, such as N-ethyl-N'-nitro-N-nitrosoguanidine and N-ethyl-N-nitrosourea, were more potent inducers for the umuC than for the alkA system. Similar but less striking effects on the two systems were obtained with SN2 type alkylating agents.     

Role of virus inhibitory factor or interferon in the antitumoral effect of whole-body hyperthermia

The interferon inducing effect of hyperthermia was studied in normal and tumor-bearing mice. Circulating interferon was temporarily detected one day after subcutaneous transplantation of 1.6 X 10(6) Ehrlich's ascites tumor cells. Hyperthermia of 43.5 degrees C for 5 min did not induce the interferon formation in mice with or without subcutaneous tumor of the cells. These findings showed that the induction of interferon formation was not main cause of the hyperthermia-induced tumor inhibition.     

Purification of a fibrolast-inhibitory factor from Actinobacillus actinomycetemcomitans Y4

Abstract A factor showing inhibitory activity against human gingival fibrolasts was extracted from the cytosol fraction of Actinobacillus actinomycetemcomitans Y4. The activity markedly inhibited the proliferation of human gingival fibrolasts, but had no effect on cell viability or gross morphology. No such activity was found in cytosol fractions from either Porphyromonas gingivalis 381 or Escherichia coli HB101. The extract from A. actinomycetemcomitans Y4 was then purified by anion-exchange chromatography, hydroxyapatite chromatography and gel-filtration chromatography to give a single band on SDS-PAGE with an apparent molecular mass of 65 kDa. The purification ratio was 183-fold with a recovery rate of 5% compared with the crude extract (starting material) when the activity was assessed by direct cell counts.     

Experimental and clinical chronocardiology

Recent advances of the chronobiologic approach to experimental and clinical cardiology was reviewed. First, the maximum entropy method (MEM) was introduced as one of the statistical methods analyzing the circadian periodicity. The MEM power spectrum showed a remarkable resolution property. It will play an important role in chronocardiology in cooperation with the cosinor method. Secondly, recent investigations of the relationship between sleep states and cardiac arrhythmias were mentioned from the viewpoints of both experimental and clinical chronocardiology. Next, recent remarkable advance on myocardial ischemia was reviewed. A marked circadian rhythm in the frequency of myocardial infarction onset and sudden cardiac death has been observed. Lastly, a reference has been made to the recent development of ambulatory BP monitoring. A chronobiologic approach to the analysis of time-series data in cardiology will lead to many advantages in clinical practice.     

Purification and characterization of an antibacterial factor from snail mucus

The antibacterial factor from the body surface of the African giant snail, Achatina fulica Férussac, was isolated by DEAE-Toyopearl 650M ion exchange chromatography. The isolated preparation exhibited highly positive antibacterial activity both for the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and for the Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, but it lost such activity when heated at 75 degrees C for 5 min. The antibacterial factor of the snail mucus was a glycoprotein whose molecular weight (MW) was about 160,000. It was composed of two subunits of MW 70,000-80,000.     

In situ analysis of centromere segregation in C57BL/6 x Mus spretus interspecific backcrosses

The analysis of major satellite sequence differences between Mus spretus and laboratory mice provides a robust method for analyzing the centromere location for the genetic maps of each mouse chromosome. Fluorescence in situ hybridization (FISH) of a genomic probe, pMR196, for the laboratory mouse major satellite sequences was used to identify C57BL/6Ros (B6) pericentromeric heterochromatin in progeny of reciprocal backcross matings. These included 80 (B6xM. spretus)F₁xM. spretus progeny (BSS) and 70 (B6xM. spretus)F₁xB6 (BSB) progeny. FISH analysis of pericentromeric heterochromatin was conducted on the same metaphase spreads that were karyotypically analyzed for chromosomespecific banding patterns. Analysis of chromosomal segregation suggested that there was not primary deviation from random assortment during meiosis in the interspecific hybrid female, because nearly all of the 190 pair-wise comparisons did not deviate from expected and because there was no consistent pattern of deviation of the same chromosomes in the reciprocal backcross progeny from similar (C57BL/6xM. spretus)F₁ hybrid females. These results affirm the value of using the major satellite to genetically mark pericentromeric heterochromatin in the analysis of the segregation and assortment of centromeres in Mus interspecific crosses.     

Electric field control of lipase membrane activity

Lipase (EC 3.1.1.3., from Pseudomonas sp.) was entrapped in collagen membrane containing liquid crystal (4-methoxybenzilidene-4′-n-butylaniline). The activity of the lipase–liquid crystal membrane at an applied voltage of 4 V was 3.4 compared to a membrane tested without imposition of an external electric field. A linear relationship was observed between the activity of the lipase–liquid crystal membrane and the current. The apparent Michaelis constant (K′_m) of the lipase–liquid crystal membrane under electric field was identical to that of the membrane under ordinary condition. Activation of the lipase–liquid crystal membrane was observed repeatedly, i.e., activation in the presence of an electric field and reversion to a basal level upon removal of the field occurred cyclically. Activity control of immobilized enzymes is desirable for switching devices of a bioreactor. Possible mechanisms of the lipase activation by electric field are discussed.     

Stimulative effect of prostaglandins on production of hexosamine-containing substances by cultured fibroblasts (2) early effect of various prostaglandins at various doses

Early effects of various prostaglandins on the production of hexosamine-containing substances by cultured fibroblasts, which were derived from a rat carrageenin granuloma, were studied. At the stationary phase, the cells were exposed for 6 h to one of the prostaglandin A₁ (PGA₁), A₂, B₁, B₂, D₂, F_1α, F_2α, E₁, E₂ or arachidonic acid in various concentrations ranging from 0.01 to 10 μg/ml for all the stimuli and from 10 pg to 10 μg/ml for PGF_2α. The activity of the cells in incorporating ³H-glucosamine into hexosamine-containing substances (acidic) glycosaminoglycans and glycoproteins) during this period was compared with that of control cells. All the stimuli tested showed more or less stimulative effect on the synthesis of hexosamine-containing substances at their specific concentrations. PGF_2α was found to be the most potent stimulant and its stimulative effect was found significant even at the low concentration of 100 pg/ml. PGD₂, F_1α and E₂ were the next potent stimuli. Their optimum dose were around 1 μg/ml but they still had significant stimulation at the concentration of 0.01 μg/ml. Effect of PGE₂ was rather mild. Stimulation by PGA₁, A₂, B₁ and B₂ or arachidonic acid was seen at high dose, and its seemed to be non-specific. The results suggested that these prostaglandins such as PGF_2α, D₂, F_1α and E₂ play some important role on regulating the production of intercellular ground substances.