Skin-tumor-initiating ability of benzo(a)pyrene-7,8-diol-9,10-epoxide (anti) when applied topically in tetrahydrofuran

The skin-tumor-initiating abilities of various metabolites of benzo(a)pyrene (BP) were determined in mice by using a two-stage system of tumorigenesis. We previously reported that BP-7,8-dihydrodiol (+/- trans) was approximately as potent as BP, suggesting that it may be a proximate carcinogen, but the alleged ultimate carcinogen of BP [BP-7,8-dihydrodiol-9,10-epoxide (anti)] was a weak tumor initiator (Cancer Lett.2: 115, 1976). Because of its high reactivity, the tumor-initiating ability of the BP-7,8-dihydrodiol-9,10-epoxide (anti) was determined by using acetone, benzene, and tetrahydrofuran (THF) as the solvent vehicles. The 'diol-epoxide' of BP was found to be an effective tumor initiator when applied topically in THF. The effectiveness of the various vehicles for the 'diol-epoxide' was as follows: THF greater than benzene greater than acetone; however, acetone was the best solvent for BP tumor initiation. The BP-9,10-dihydrodiol and BP-3-hydroxy were found to be weak tumor initiators. BP-3-hydroxy was also tested for tumor-promoting ability and was found to be inactive in this capacity.

[Experimental studies on the renal tolerance of cefuroxime (author's transl)]

The potential renal tolerance of cefuroxime was investigated in 80 female albino Wistar rats and compared with that of cephacetrile. The drugs were administered i.m. in different dosages (1000, 2000, 3000 and 5000 mg/kg/day; dosage interval: 12 h) over a period of five days. The excretion of tubular cells and urinary malic dehydrogenase was assessed before, during and after administration of the antibiotics. In addition, the concentration of serum urea was analysed and the renal histology was examined. The following toxic threshold doses were estimated: cefuroxime 5000 mg/kg/day, cephacetrile 3000 mg/kg/day. In comparison with other cephalosporines cefuroxime belongs to those antibiotics with which a high degree of renal tolerance is demonstrated.

Molecular basis for several drug-induced nephropathies

A recent clinical advance has been the discovery that many drug-induced hepatic diseases result from the metabolic activation of chemically stable drugs to potent alkylating agents by the liver. In addition to the liver, however, the kidney also contains active enzyme systems capable of metabolically activating drugs and other chemicals. For this reason a systematic investigation of the possible role of metabolic activation in the pathogenesis of several drug-induced renal diseases has been undertaken. These laboratory results are reviewed in the light of the clinical spectrum of the renal injuries, and possible therapeutic implications of these new findings are briefly discussed. The potential use of these models of nephrotoxicity to probe a variety of physiologic and pathophysiologic mechanisms of renal function are noted.

Some pharmacological studies on the cardiotonic effects of furanosteroidal glycosides

Cardiotonic effects and cardiotoxicities of three furanosteroidal glycosides were compared with those of standard cardiac glycosides (digitoxin, gitoxin, etc.). Furanosteroidal glycosides showed positive inotropic effects in both isolated guinea-pig atria and rabbit hearts. The positive inotropic effect of 17beta-(3-furyl)-5beta,14beta-androstane-3beta,14,16beta-triol-3-bisdigitoxoside(FGBD) corresponded to that of digitoxin in isolated guinea-pig atria and frog hearts. Intravenous and oral administration of FGBD and 17beta-(3-furyl)-5beta,14beta-androstane-3beta,14,16beta-triol-3-tridigitoxoside(FGTD) in higher doses induced cardiac arrest after vomiting, bradycardia, ventricular rhythm, and ventricular fibrillation in pigeons and cats. Comparison of lethal doses between intravenous and oral administration of cardiac glycosides in pigeons and cats suggested that gastrointestinal absorption of FGBD and FGTD is inferior to that of digitoxin but superior to that of gitoxigenin bisdigitoxoside and gitoxin. Cardiotonic effects of furanosteroidal glycosides were confirmed in isolated guinea-pig, rabbit and frog hearts.

Evaluation of monensin toxicity in the horse

Gelded horses of mixed breeding, ranging in weight between 360 and 455 kg, were fed pellets that contained monensin at concentrations of 279, 124, 31, and 0 ppm. Of 2 horses fed 279 ppm (253 g/T), both died. Of 3 horses fed 125 ppm (113 g/T), 1 died; feed intake was reduced in the 2 survivors. Of 3 horses fed 31 ppm (28 g/T), 1 had a transitory reduction in feed intake and the other 2 remained clinically normal. The 2 horses fed 0 ppm remained clinically normal. Monensin was also given to horses by gavage, at dosages of 1, 2, 3, 4, or 20 mg/kg of body weight. The LD50 was estimated to be between 2 and 3 mg/kg of body weight. The signs of toxicosis were partial to complete anorexia, ataxia, and intermittent profuse sweating.

Acute cytogenetic effect of 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2, a food preservative) on rat bone marrow cells in vivo

The cytogenetic effects of 2(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2), a food preservative used in Japan, on rat bone marrow cells in vivo were studied. The aberrant metaphase cells in the bone marrow increased and reached the peak level 6 h after intraperitoneal injection of 240 mg/kg body weight of AF-2 and returned to the normal level within 24 h. A dose-response relationship was obtained using 4-240 mg/kg of AF-2. Chromosome aberrations were also induced after oral administration of 30-240 mg/kg. The aberrations were mostly chromatid breaks and the distribution among and within chromosomes was similar to those induced by a carcinogen, 7, 12-dimethylbenz(a)anthracene (DMBA). The present results provide the first evidence of in vivo cytogenetic effects of AF-2 on mammalian cells and, together with the evidence of mutagenicity already proved in other organisms, warn of the possible genetic hazards to cells exposed to this compounds.

Teratogenic effects of cyclopamine and jervine in rats, mice and hamsters

Golden hamster fetuses were extremely sensitive to the teratogenic action of jervine and cyclopamine, the steroidal alkaloid tetratogens from Veratrum californicum. Cebocephaly, harelip/cleft palate, exencephaly, and a cranial bled were the common deformities produced by dosing on the seventh day of gestation. Sprague-Dawley derived albino rats were susceptible to cyclopamine but not to jervine, and at an incidence very much lower than that of hamsters. Cebocephaly and microphthalmia were the common deformities. The terata were observed as a consequence of sixth to ninth-day dosings. Single-day dosings produced no terata. Swiss Webster mice were apparently resistant to the teratogens.

Statistical analysis on toxicity of a nitrofuran derivative, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide

A food additive, furylfuramide or AF-2, which had been used in Japan since 1965 and structurally is composed of 5-nitro-2-furyl radical and acrylamide, was re-examined mainly on chronic toxicity by statistically reviewing published data. The conclusions are as follows: 1) The maximum safety dosage which shows no demonstrable change in rats must be corrected at least to 1/170 of the value which has been accepted by the Ministry of Health and Welfare of Japan (MHW). 2) The minimum effective dose to bacterial growth in food can not be lowered below the standard usage level with MHW determined, because the inactivation factor in food, decreasing effectivity to 1/20, must be taken into consideration. 3) In view of these two facts, AF-2 is found to be unacceptable as a food additive. 4) Great importance must also be attached to the possibility of mutagenicity and carcinogenicity of AF-2, pointed out recently. Both neurotoxicity and dermatitis observed in tofu (soybean curd) makers are also memtioned.

The preparation and intravenous anaesthetic activity of tetrahydrofuran-3-ols

A number of tetrahydrofuran-3-ols have been prepared and examined for intravenous anaesthetic activity. The compounds studied had low intrinsic anaesthetic activity and there was an inverse relation between anaesthetic activity or toxicity and solubility in water. It was considered unlikely that compounds comparable in activity to thiopentone or methohexitone would be found in this series.