[Toxicological studies on pepleomycin sulfate (NK 631). I. Acute toxicity of pepleomycin in mice, rats and dogs (author's transl)]

Studies on acute toxicities of pepleomycin sulfate were carried out in both sexes of mice and rats, comparing with bleomycin, and male dogs. Pepleomycin was administered subcutaneously, intravenously and intraperitoneally in both sexes of mice and rats, and intravenously in male dogs respectively. Mice and rats, and intravenously in male dogs respectively. Mice and rats were observed respectively for 10 and 14 days after the administration. LD50 values were calculated by the method of Litchifield & Wilcoxon. LD50 values of pepleomycin were 4 approximately 6 times smaller than those of bleomycin in all routes of mice, but difference between them was not significant in all routes of rats. Additionally sex-difference of LD50 values was scacely recognized in all routes of both species. Toxicological findings observed in common to all routes of both species were ataxia, depression, tremor and epiphora, and only in all routes of mice, head-twitch, running-round and rolling were especially recognized as toxic behavior, which were not observed in bleomycin. Hepatic and renal lesions were recognized in biochemically and histopathologically in the survived rats. The dogs treated with pepleomycin 50 and 30 mg/kg had the decrease in food intake and the loss of body weight. They became moribund in 9 approximately 36 days after administration. In these dogs the lesions of liver and kidney were severely recognized in biochemical and histopathological findings. One of them which received 50 mg/kg recovered biochemically and histopathologically in 209 days after administration by the supplemental nutrition in early stage.

[Safety evaluation of NK 631. Antigenicity, effect on delated hypersensitivity, irritative effect on eye mucous membrane and mutangenicity of pepleomycin (NK 631) (author's transl)]

1. Whether NK 631 is antigenic to guinea pigs and rabbits was studied by the methods of active and passive anaphylactic shock tests, Schultz-Dale reaction, passive cutaneous anaphylaxis, Ouchterlony, tanned red cell haemagglutination test and test according to the U.S. Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics. However, none of the tests proved NK 631 to be antigenic. 2. The immunosuppressive effect of NK 631 was studied by delayed hypersensitivity to picryl chloride in normal and L-1210 tumor bearing mice. Therapeutic dosis of NK 631 was no immunosuppressed but toxic dosis of NK 631 was slightly decreased in ear thickness of delayed hypersensitivity. 3. The acute irritative effect of NK 631 and of bleomycin was studied by single instillation to the rabbit eye mucous membrane with 0.1 ml of either of 10, 33 and 100 mg/ml solution of the drugs in physiological saline. The irritative effect of NK 631 on the eye mucous membrane at each concentration was slightly severe than that of bleomycin at the same concentration. However, the manifestations were only mild to moderate dilatation of the conjunctival and nictating membrane blood vessels and eye mucous, and recovered or were mitigated 48 hours after the instillation. No severe changes such as corneal opacity, corneal desquamation, swelling and deaquamation of the conjunctival and nictating membrane were observed. The histopathological examination revealed no striking changes. 4. Mutagenicity of NK 631 and of bleomycin on Salmonella typhimurium strain TA 100 and TA 98 was studied. It was definitely shown that neither NK 631 nor bleomycin exerted any mutagenic action on either test strains.

[Toxicological studies of pepleomycin sulfate. V. Short term intermittent toxicity in dogs (author's transl)]

The comparative studies in the short term intermittent toxicity of pepleomycin (NK631) and bleomycin (BLM) were performed on 10 beagle dogs of 13 approximately 15 months old. Two dogs per group were injected intravenously with NK631 and BLM in doses 5.0 and 2.5 mg/kg body weight every fourth day for 11 treatment. Two dogs served as control and were injected with saline solution. In the group of 5.0 mg/kg of NK631, one dog was sacrificed on day 37 of the treatment and another one dog died on day 33 of the treatment. All the dogs of other group survived until the end of the treatment. The toxicity to the hepatic and renal damage caused by NK631 was stronger than the BLM. On the contrary, the toxicity to lung and various mucocutaneous regions was weaker than the BLM. The grade of pulmonary fibrosis of NK631 was about 1/2 and 2/3 of the BLM in dose of 5 mg/kg and 2.5 mg/kg, respectively. Other toxicological changes such as anorexia and weight loss were almost similar to the BLM.

C-peptide immunoreactivity (CPR) in urine

Human urinary C-peptide immunoreactivity (CPR) was measured by a double-antibody radioimmunoassay using synthetic human C-peptide. Urine CPR was stable as long as one year, if stored frozen. Urine CPR was eluted by gel filtration as a single peak in the region that corresponded to 125I-labeled C-peptide. Even in a patient with insulin antibody whose serum contained a CPR fraction with higher molecular weight, urine CPR was eluted in its expected region.

Normal subjects excreted 81 ± 36 μg. CPR per day. Urine CPR excretion was very low in juvenile-onset diabetics, variable in adult-onset diabetics and liver disease patients, and increased in patients on corticosteroid treatment. Diurnal changes and a 50-gm. glucose tolerance test revealed that urine CPR excretion rate increased in parallel with plasma CPR levels. The responses of diabetic patients were smaller and more sluggish. Urine CPR excretion tended to be decreased in patients with renal diseases and extremely low in those on regular hemodialysis. CPR was positively correlated with serum creatinine. Urine CPR was not increased in patients with marked β2-microglobulin excretion.

Highly significant correlations were observed between 24-hour urine CPR values and fasting plasma CPR or summed CPR after glucose load. Thus, urine CPR seems to provide a good means to assess B-cell function, and it is particularly suitable to monitor B-cell function continuously or when multiple blood samplings are not practical. Continuous measurement of daily urine CPR in diabetic patients on glibenclamide treatment revealed that improvement of blood sugar control could occur without preceding increases in total daily B-cell secretion.

Intracellular reduction of the cupric ion of bleomycin copper complex and transfer of the cuprous ion to a cellular protein

The cupric ion of the bleomycin copper complex has been shown to be reduced and transferred to a cellular protein by the following mechanism: Bleomycin approximately Cu2+ leads to Bleomycin plus Cu+ X Cu+ plus M leads to M approximately Cu+. The intracellular reducing agents (X) are suggested to be sulfhydryl compounds, because their action is inhibited by N-ethylmaleimide. The active group of the cellular protein (M) that binds with the cuprous ion is suggested to be a sulfhydryl group. The action of the bleomycin copper complex in causing DNA fragmentation in cells can be explained by the mechanism presented in this paper. This mechanism in cells is also supported by the temperature dependency of the action of the bleomycin copper complex on cells.

A new synthesis of 5'-deoxy-8,5'-cyclo-adenosine and -inosine: conformationally-fixed purine nucleosides (nucleosides and nucleotides. XVI)

A versatile method for the synthesis of 5'-deoxy-8,5'-cycloadenosine, a conformationally-fixed "anti" type of adenosine, was presented. Irradiation of 2', 3'-O-isopropylidene-5'-deoxy-5'-phenylthioadenosine with 60W Hg vapor lamp afforded 2',3'-O-isopropylidene-5'-deoxy-8,5'-cycloadenosine in high yield. The use of other 5'-alkylthio derivatives also gave the cycloadenosine, though the yields were rather poor. Deacetonation of the cyclocompound with 0.1N HCl gave 5'-deoxy-8,5'-cycloadenosine. The cycloinosine derivative was similarly prepared. The nmr, mass and CD spectra of 5'-deoxy-8,5'-cycloadenosine were given and discussed with the previously reported results.

Disappearance rate of endogenous human C-peptide from blood

Glucagon (1 mg) and glucose (60 ml of 50% solution) were infused over 60 min to three normal and one obese subjects and two insulinoma patients. Plasma C-peptide immunoreactivity (CPR) and immunoreactive insulin (IRI) increased during the infusion. Half time of CPR after cessation of the infusion was 20.1 +/- 4.0 min, and that of IRI 9.8 +/- 1.3 min, respectively. This difference partly explains the higher molar concentration in plasma of CPR than IRI.

Human C-peptide immunoreactivity (CPR) in blood and urine - evaluation of a radioimmunoassay method and its clinical applications

A double-antibody radioimmunoassay method, using synthetic human connecting peptide as an immunizing antigen and standard, was evaluated for clinical assay of blood and urine samples. Normal fasting blood connecting peptide immunoreacivity (CPR) was 2.45 +/- 0.96 ng/ml, increasing promptly after a 50 g oral glucose load, but somewhat slower than insulin. Molar concentration of CPR exceeded that of insulin. CPR responses to glucose were subnormal in diabetics, very low in juvenile-type cases, and often poor in patients on insulin treatment. Fasting CPR levels were elevated in patients on corticosteroid treatment and with uraemia. A patient with insulin "auto-antibody" had high serum CPR. A considerable amount of CPR appeared in urine. Normal daily excretion of CPR was 1.52 +/- 0.55 mug/kg or 55.1 +/- 18.2 ng/mg creatinine. Urine CPR was very low in juvenile-type diabetics, and elevated in patients on corticosteroid treatment. The results confirm that blood and urine CPR are useful measures of the endocrine pancreatic function.

Synthesis and reaction of some 6-substituted pyrimidine nucleosides

Treatment of 5-bromouridines with sodium cyanide afforded 6-cyanouridines. Further treatment of the 6-cyano derivatives with cyanide ion at higher temperature gave the 5-cyanouridines. The 6-cyano group was transformed to thioamido, carboxy, chloromethyl cyanomethyl, carboxymethyl, and methyl group, respectively. 5-Bromocytidines were also converted to the 6-cyanocytidines, from which cytidine 6-carboxylic acid was derived. The cyano group of 6-cyanocytidines has a leaving ability toward nucleophilic substitution reactions. The circular dichroic spectra of various 6-substituted pyrimidine nucleosides showed positive Cotton effect at B2u region, which were in contrast to the reported negative bands in 6-methyl-uridine or-cytidine.