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Continued administration of several hepatocarcinogens led to an increase in the concentration of glutathione (GSH) in the livers of intact, but not of hypophysectomized or adrenalectomized rats. The concentration of GSH remained high untill the development of hyperplastic nodules. Subsequently, the concentration of GSH dropped to the normal level or below. A single dose of 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) produced an increase of GSH which, within a certain range, depended upon the amount of the carcinogen. In well differentiated, slowly growing hepatomas, the concentration of GSH approached the level in normal adult rat liver. On the other hand, in nondifferentiated and rapidly growing hepatomas, GSH was only 30-40% of that in normal liver. The activity of gamma-glutamyl transpeptidase (GTase) increased within 24-48 hours after a single large dose of 3'-Me-DAB. Continued feeding of 3'-Me-DAB led to an exponential increase of GTase. During hepatocarcinogenesis, the level of GTase activity corresponded to the degree and size of pathologic changes produced in rat liver. Chloramphenicol partially inhibited the increase of GTase induced by 2-acetylaminofluorene. Pretreatment with 3-methylcholanthrene partially inhibited the increase of GTase that had been induced by a single dose of 3'-Me-DAB. Puromycin partially inhibited the increase of GTase induced by several doses of dimethylnitrosamine. These observations indicated a close connection between the activation of GTase and chemical carcinogenesis in rat liver. Measurements of GTase activity in 12 Morris hepatomas supported this conclusion; their GTase levels were greatly elevated compared with that in normal adult rat liver.

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BackgroundLaryngeal tube (LT) application by rescue personnel as an alternate airway during the early stages of out-of-hospital cardiac arrest (OHCA) is still subject of debate. We evaluated ease of handling and efficacy of ventilation administered by emergency medical technicians (EMTs) using LT and bag-valve-mask (BVM) during cardiopulmonary resuscitation of patients with OHCA.MethodsAn open prospective randomized multicenter study was conducted at six emergency medical services centers over 18 months. Patients in OHCA initially resuscitated by EMTs were enrolled. Ease of handling (LT insertion, tight seal) and efficacy of ventilation (chest rises visibly, no air leak) with LT and BVM were subjectively assessed by EMTs during pre-study training and by the attending emergency physician on the scene. Outcome and frequency of complications were compared.ResultsOf 97 eligible patients, 78 were enrolled. During pre-study training EMTs rated efficacy of ventilation with LT higher than with BVM (66.7% vs. 36.2%, p = 0.022), but efficacy of on-site ventilation did not differ between the two groups (71.4% vs. 58.5%, p = 0.686). Frequency of complications (11.4% vs. 19.5%, p = 0.961) did not differ between the two groups.ConclusionsEMTs preferred LT ventilation to BVM ventilation during pre-study training, but on-site there was no difference with regard to efficacy, ventilation safety, or outcome. The results indicate that LT ventilation by EMTs during OHCA is not superior to BVM and cannot substitute for BVM training. We assume that the main benefit of the LT is the provision of an alternative airway when BVM ventilation fails. Training in BVM ventilation remains paramount in EMT apprenticeship and cannot be substituted by LT ventilation.Trial registration ClinicalTrials.gov (NCT01718795).Electronic supplementary materialThe online version of this article (10.1186/s13049-017-0446-1) contains supplementary material, which is available to authorized users.