Effect of iron concentrations on the DNA-degradation reaction by bleomycin

DNA-degradation reaction by bleomycin was conducted with form I of SV40 DNA as the substrate under "iron-limited conditions" and "iron-sufficient conditions". For "iron-limited conditions", the iron ions in reaction mixtures were derived from contaminant iron in the bleomycin preparation, the molar ratio of bleomycin/iron being 1/0.05. For "iron-sufficient conditions", Fe(II) was added to reaction mixtures to attain the molar ratio of bleomycin/iron at 1/1 to 1/29. DNA-degradation reaction by Fe(II) without bleomycin, or "Fe(II) alone", was also run for comparison. In any case, the reaction was allowed to proceed at such low rates that other products than form II and form III, due to further fragmentation, were negligible. The mass of DNA in each form was quantitatively determined by spectrofluorometry after agarose gel electrophoresis and staining with ethidium bromide. "Iron-limited conditions" and "iron-sufficient conditions" showed similar reaction characteristics as follows. As form I decreased with incubation time, form II increased faster than form III, hit a plateau (ca. 65% of total DNA) and decreased gradually thereafter. Form III kept increasing throughout the incubation. The reaction was dependent on incubation time and on doses of both bleomycin and Fe(II) but rather independent of temperature. The reaction was inhibited by acidic pH, Tiron (a specific chelator of iron) and Cu(II) but not EDTA. Octanucleotides with specific base sequence inhibited the reaction. DNA-degradation reaction by "Fe(II) alone" showed different characteristics as follows. The reaction proceeded rapidly at first, but ceased within 2 minutes. The extent of reaction was dependent on dose of Fe(II). The reaction product was form II accompanied by little amount of form III. The reaction was highly dependent on temperature, inhibited by EDTA, and not inhibited by Cu(II) and acidic pH. Octanucleotides, irrespective of their base sequences, inhibited the reaction.     

A comparative, well-controlled study of ceftizoxime suppository against ceftizoxime intravenous injection in infantile acute pneumonia

We have attempted to clinically define the therapeutic usefulness of ceftizoxime suppository (CZX-S) in children with bacterial pneumonia, in a randomized trial. Intravenous injection of ceftizoxime (CZX) was used as the control. The results are summarized below. Subjects were inpatients with bacterial pneumonia, ranging in age from 9 months to 7 years and 10 months. As a rule, the daily dose was either four 250 mg (in potency) suppositories given at 6-hour intervals or 60 mg/kg body weight intravenous CZX (control) given in 4 injections at 6-hour intervals over a period of 7 days. The number of children in the study was 67. These children were divided into 2 dosage groups (suppository, 35; injection, 32) with matching pretreatment background factors. The severity of the target disease in the majority of the children was "moderate". The rate of therapeutic effectiveness was 97.1% for the suppository and 93.8% for the injection, and did not differ significantly between the 2 groups. Rates of efficacy by severity, presence or absence of underlying diseases, daily dose and/or complications were high without exception, and did not differ significantly between the 2 groups. Eradication rates for causative microorganisms, as studied in 16 children of each group, were both 93.8%. The 2 most frequently isolated causative organisms were Haemophilus influenzae and Streptococcus pneumoniae. Side effects were examined for 36 children of each group. The frequency of side effects did not differ significantly between the suppository group (2 with diarrhea and 1 with abdominal pain) and the injection group (1 with urticaria), and 8.3% and 2.8%, respectively. The frequency of abnormal laboratory test findings differed significantly (P less than 0.01) with respect to eosinophilia which occurred in 7 (20.6%) of the injected subjects but was not encountered in the subjects treated with suppositories. Other abnormal laboratory findings included thrombocytosis in 3 (14.3%) of the injection group and increased GOT in 1 (3.2%) of the suppository group. The suppository formulation of CZX appears to be a highly useful substitute for the injectable form, and should find a special use in children whose treatment with injections experiences some difficulty.     

Artificial Liver: Present and Future

Early in 1956, the first model of a biological artificial liver, using a live dog's liver incorporated in a cross-hemodialyzer, was placed in an experimental animal with portocaval encephalopathy. This "biological artificial liver," a hybrid artificial liver in the present terminology, was the first in the world. In October 1958, the first human patient, a young male patient in hepatic coma due to liver cirrhosis, was placed on the laboratory-made biological artificial liver composed of four parabiotic cross-hemodialyzers connected with four live dogs' livers to which the "hepatic reactors" for ammonium adsorption and acid-base balance were additionally equipped. This first case was very successful, resulting in the patient's recovery from coma. This article introduces the past history of the artificial liver, research of which has mainly been conducted in Japan since the early 1950s by the author, M. Mito, and Y. Nosé. Until recently, little progress has been made in this field through the application of blood purification principles such as hemoadsorption, plasmapheresis, and other modifications and combinations. Accumulation of clinical experiences with such conventional methods has stimulated the third generation of the artificial liver to a return to a hybrid organ applying modern science and technology. A concept of hybrid organs in comparison with organ transplants is introduced. The Japanese national project of developing a new artificial liver system, as conducted by the author as the chairman and his associates, is introduced.     

Enflurane reduces the excitation and inhibition of dorsal horn WDR neuronal activity induced by BK injection in spinal cats

The effects of enflurane (0.5%, 1.5% and 2.5%) on the excitation and inhibition of dorsal horn wide dynamic range (WDR) neuronal activity induced by bradykinin (BK) injection was studied in spinal cats. Extracellular activity was recorded in the dorsal horn from single WDR neurons responding to noxious and non-noxious stimuli applied to the cutaneous receptive fields on the left hind paw foot pads of decerebrate, spinal cord transected (L_1–2) cats. When 10µg of BK was injected into the femoral artery ipsilateral to the recording site as the noxious test stimulus, 24 of 26 WDR neurons (92%) gave excitatory responses and 2 (8%) gave inhibitory resposes. On the other hand, when the injection of 10µg of BK into the femoral artery contralateral to the recording site was used as the noxious test stimulus, 7 of 12 WDR neurons (58%) gave inhibitory responses, 3 (25%) gave excitatory responses, and 2 (17%) showed no response. The excitatory neuronal activity in WDR neurons was not depressed by 0.5% or 1.5% enflurane but was depressed significantly by 2.5%. However, the inhibitory neuronal activity in WDR neurons was significantly depressed by 0.5%, 1.5% and 2.5% enflurane. We have found that enflurane reduces the excitation as well as the inhibition of dorsal horn WDR neuronal activity induced by BK injection. These results suggest that the reduction of excitatory and inhibitory responses produced by noxious stimulation is likely to be the fundamental basis of the enflurane-induced anesthetic state in terms of WDR neurons.(Nagasaka H, Nakajima T, Takano Y et al.: Enflurane reduces the excitation and inhibition of dosal horn WDR neuronal activity induced by BK injection in spinal cats. J Anesth 4: 102–109, 1990)     

Contribution of Monoamine Oxidase(MAO) to the Binding of Tertiary Basic Drugs in Isolated Perfused Rat Lung

The effect of tertiary basic drugs on mitochondrial MAO activity and the effect of MAO inhibitors (MAOIs) on basic drug accumulation in the isolated perfused rat lung were studied to clarify the role of MAO in drug binding to lung tissue. In the perfused lung preparation, the inhibition of MAO by basic drugs correlated well with their lipid solubilities and followed competitive kinetics. The inhibitory rank order (imipramine diphenhydramine > quinine > metoclopramide > procainamide) also correlated with their accumulation in the perfused lung. Moreover, MAOI treatment decreased the accumulation of basic drugs in the lung, and the potency of MAOIs to inhibit drug accumulation in the lung correlated with their MAO inhibitory activity. These results indicate that lung MAO has specific binding sites for basic drugs and may function as a drug reservoir.     

Cdc7 kinase is required for postnatal brain development

The evolutionally conserved Cdc7 kinase plays crucial roles in initiation of DNA replication as well as in other chromosomal events. To examine the roles of Cdc7 in brain development, we have generated mice carrying Cdc7 knockout in neural stem cells by using Nestin-Cre. The Cdc7^Fl/Fl Nestin^Cre mice were born, but exhibited severe growth retardation and impaired postnatal brain development. These mice exhibited motor dysfunction within 9 days after birth and did not survive for more than 19 days. The cerebral cortical layer formation was impaired, although the cortical cell numbers were not altered in the mutant. In the cerebellum undergoing hypoplasia, granule cells (CGC) decreased in number in Cdc7^{Fl/F l}Nestin^Cre mice compared to the control at E15-18, suggesting that Cdc7 is required for DNA replication and cell proliferation of CGC at mid embryonic stage (before embryonic day 15). On the other hand, the Purkinje cell numbers were not altered but its layer formation was impaired in the mutant. These results indicate differential roles of Cdc7 in DNA replication/cell proliferation in brain. Furthermore, the defects of layer formation suggest a possibility that Cdc7 may play an additional role in cell migration during neural development.     

Pharmacological effects of concomitant administration of β-adrenoceptor blocker and agonist in normal subjects: characterization by heart rate response to exercise

The effects of a combination regimen of metoprolol and ₁-adrenoceptor agonist denopamine on resting and exercise heart rate have been studied in 10 normal volunteers. Maximal ramp upright bicycle exercise was performed three times at 1-week intervals. Two hours before each exercise test, 5 mg metoprolol plus 20 mg denopamine, 5 mg metoprolol plus a denopamine placebo, or two placebos were orally administered in a double-blind fashion.During exercise after placebo administration, heart rate increased in parallel with the exercise intensity. Compared to the placebo values, resting heart rate was significantly decreased by an average of 10 beats · min^–1 by 5 mg metoprolol, whereas it was not altered by the combination regimen. During exercise, however, both the combination regimen and metoprolol alone showed a significant negative chronotropic effect, decreasing peak exercise heart rate by an average of 14 and 21 beats · min^–1, respectively. Peak oxygen uptake was also significantly decreased by both regimens.We conclude that concomitant administration of 5 mg metoprolol and 20 mg denopamine exerts an effective -adrenoceptor blocking action during exercise but a minimal effect at rest in normal subjects. The combination regimen appears to have a favourable pharmacological profile for -adrenoceptor blocker therapy in patients with chronic heart failure.