5-(3-Hydroxymethyl-3-methyl-1-triazeno imidazole-4-carboxamide is a metabolite of 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DIC, DTIC NSC-45388)

The cancer chemotherapeutic drug, 5-(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide (DIC, DTIC, NSC-45388), is metabolised in rats to a structurally related product which was detected by thin-layer chromatography. The novel metabolite has a lower mobility and a colour reaction that is indistinguishable from the parent compound. The metabolite is not retained on an anionic exchanger which is inconsistent with the expected covalent binding of the drug to endogenic anionic substrates (e.g. glucuronic acid). Since both DIC and the metabolite yielded 5-[(4-ethylamino-1-napthyl)-azo]imidazole-4-carboxamide through release of 5-diazoimidazole-4-carboxamide, followed by coupling with N-ethyl-1-napthylamine, no biotransformation (hydroxylation) of the imidazole moiety of the injected DIC had occurred. By corollary, the lowered chromatographic mobility of the metabolite was explicable by the introduction of a polar but non-acidic function into the terminal dimethylamino group of the triazene side-chain. The metabolite was identified as 5-(3-hydroxymethyl-3-methyl-1-triazeno)imidazole-4-carboxamide by co-chromatography with an authentic sample of HMIC and by its methylating capacity for nucleophilic substrates.

Developmental factors contributing to the susceptibility to bradycardia in isolated, cultured fetal mouse hearts

A propensity for bradycardia in preterm human infants suggested that the heart rate response to cholinergic stimulation may vary during development. Isolated, intact fetal mouse hearts (FMH) in organ culture were used as a model to explore developmental differences in chronotropic response to cholinergic stimulation. FMH's of gestational ages (GA) from 13-22 days, maintained for 36 hr in culture, were exposed to acetylcholine (AcH) with and without prior addition of physostigmine. Heart rate decreased markedly with 10(-4) and 10(-6) M AcH (84 +/- 3 and 48 +/- 4%) in 13-14 day hearts, but the decrease was progressively blunted with increasing age and was only 7 +/- 3 and 3 +/- 2% at 21-22 days GA. Physostigmine markedly enhanced the cholinergic response in older hearts with 54 +/- 4 and 32 +/- 5% decreases in heart rate with the two doses of AcH at 21-22 days. However, it did not alter the response in younger hearts. The data suggest that the chronotropic response to AcH progressively diminishes with advancing GA and the extent of intrinsic cholinesterase activity at different GA's is, in part, responsible for the decrease.

Group B streptococcal colonization in prepubertal children

Colonization of prepubertal boys and girls with group B streptococci was studied prosepctively for one year. Throat, anal canal, and vaginal cultures were obtained from 415 children not receiving antimicrobics. The over-all colonization rate at any site was 11.3% and did not vary with age, sex, or season. Streptococci were recovered most commonly from the anal canal. Throat colonization was comparable in boys and girls. A total of 71 sites were positive for the organism in the 47 colonized children. Serotype Ia was the most common (41% of isolates). Types II and III accounted for 24% and 20%, respectively. Colonization at more than one site occurred in 20 children and in two of these children, different serotypes were recovered from different sites.

[The development and the reversion of spheroplasts of a diaminopimelic acid-auxotrophic mutant of Escherichia coli]

1. The formation and reversion of spheroplasts of the diaminopimelic acid-auxotrophic mutant Escherichia coli K 12, 335, DAP-, R+TEM in a medium lacking diaminopimelic acid have been investigated by microphotography: During their development from rod form cells to spheroplasts cells on slide-surface-agar preparations underwent two successive cell divisions in the course of which the cells retained their rod form. The cells formed by these divisions partitioned into a varying number of spheroplasts of different size. The reversion of spheroplasts to rod form cells, started by the addition of diaminopimelic acid showed two characteristic steps: Each spheroplast partitioned again into several spheroplast-like cell bodies; most of them reverted directly to rod form cells. 2. The release of the R-factor mediated periplasmic TEM-beta-lactamase, E. C. 3.4.2.6., into the growth medium during the development of spheroplasts attained more than 50% of the entire TEM-beta=lactamase activity. The spheroplasts showed a multiple enhancement of TEM-beta-lactamase activity per mg cell protein compared with rod form cells.

The permeability state of the blood-brain barrier in relation with the plasma renin activity in early stage of experimental renal hypertension

The permeability state of the blood-brain barrier has been investigated in rats with renal hypertension. We have observed that the permeability of brain vessels is considerably increased both if, apart from the ischaemic kidney, the contralateral one was removed and also if we left it untouched. The plasma renin activity was only increased; compared with control animals however, in that form of hypertension where, besides the ischaemic kidney, the contralateral one remained untouched. We suppose that the change in plasma renin level does not play any essential role in the increased permeability of the blood-brain barrier.