Hrs recruits clathrin to early endosomes.

The hepatocyte growth factor-regulated tyrosine kinase substrate, Hrs, has been implicated in intracellular trafficking and signal transduction. Hrs contains a phosphatidylinositol 3-phosphate-binding FYVE domain that contributes to its endosomal targeting. Here we show that Hrs and EEA1, a FYVE domain protein involved in endocytic membrane fusion, are localized to different regions of early endosomes. We demonstrate that Hrs co-localizes with clathrin, and that the C-terminus of Hrs contains a functional clathrin box motif that interacts directly with the terminal beta-propeller domain of clathrin heavy chain. A massive recruitment of clathrin to early endosomes was observed in cells transfected with Hrs, but not with Hrs lacking the C-terminus. Furthermore, the phosphatidylinositol 3-kinase inhibitor wortmannin caused the dissociation of both Hrs and clathrin from endosomes. While overexpression of Hrs did not affect endocytosis and recycling of transferrin, endocytosed epidermal growth factor and dextran were retained in early endosomes. These results provide a molecular mechanism for the recruitment of clathrin onto early endosomes and suggest a function for Hrs in trafficking from early to late endosomes.

Function of Hrs in endocytic trafficking and signalling.

The hepatocyte growth factor-regulated tyrosine kinase substrate, Hrs, becomes tyrosine-phosphorylated upon the binding of various growth factors and cytokines to their receptors. This protein is essential for ventral folding morphogenesis, and it shares structural similarity with Vps27p, which is involved in vacuolar protein sorting in yeast. Since Hrs is localized to endosomes and has been implicated in the regulation of signal transduction as well as membrane trafficking, it has been regarded as a potential co-ordinator of endosomal receptor sorting and signalling. Here we discuss the possible functions of Hrs in light of its interactions with phosphatidylinositol 3-phosphate and multiple proteins.

Nicotinamide and methionine reduce the liver toxic effect of methotrexate.

Methotrexate is widely used as a therapeutic agent in different diseases. This therapy is connected with various side effects, including liver toxicity. We have developed a mouse model to demonstrate the toxic effects of methotrexate: mice were given 50 mg/kg acetaminophen, which itself has no effect on the liver. If, additionally, methotrexate is applied, there is an increase in the death rate, as well as in glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities. If methotrexate is administered in conjunction with either nicotinamide or methionine, the rise in the death rate and in GOT and GPT activities associated with methotrexate application is markedly reduced. On the basis of these results, it can be concluded that methotrexate therapy should be combined with either nicotinamide or methionine, respectively.

Enhancing the inhibitory effect of nicotinamide upon collagen II induced arthritis in mice using N-acetylcysteine.

We could show that both nicotinamide and N-acetylcysteine inhibit collagen induced arthritis in mice. In the present paper, using lower doses of each, we applied combinations of these two substances. We were able to confirm potentiating effects of these combinations. These results may allow new perspectives for the therapy of arthritis to emerge.

Enhancement of the effect of methotrexate on collagen II induced arthritis in mice by nicotinamide.

Treatment with a combination of 10 mg/kg i.p. methotrexate and 100 mg/kg i.p. nicotinamide inhibits the development of collagen II induced arthritis in male DBA/1 X B.10(4R) mice, as assessed by the arthritic index and whole blood chemiluminescence. The effect is much more pronounced than with either methotrexate or nicotinamide alone at the same concentrations. Determination of GOT and GPT levels in the blood revealed that the treatment causes no toxic side effects on the liver.

Practice with a 24-hour uniform.

I too share the trials of life as a practice nurse that Rosemary Cook recently bemoaned in her article 'Community relations' (Nursing Standard July 24).

[Infection studies in laboratory mice with erysipelas and coli bacteria after the administration of biotechnical substances]. / Infektionsversuche an Labormäusen mit Rotlauf- und Kolibakterien nach Verabreichung von Biotechnika.

Chlormadinone-acetate, human chorionic gonadotrophin, oestrophan, and zinc-metallibur, all of them substances used for biotechnological indications, were tested in generation experiments for their bearings on the immune status. The tests were applied to untreated descendants of biotechnologically treated mothers. Though the model animal experiments were continued through 6 generations of laboratory mice, no clue was obtained as to immunosuppressive action of any of the substances involved.

[The fertility performance (litter characteristics) of laboratory mice over 6 generations after the administration of zinc metallibure as suisynchronous premix and cloprostenol as estrophane]. / Untersuchungen zu Fruchtbarkeitsleistungen (Wurfmerkmale) von Labormäusen im Verlaufe von 6 Generationen nach Verabreichung von Zink-Metallibur als Suisynchron-Prämix und Cloprostenol als Oestrophan.

Suisynchron premix and oestrophane were tested through 6 generations of laboratory mice for their action on fertility (litter parameters). No fertility-reducing effect was recordable.

[The fertility performance (litter characteristics) of laboratory mice over 6 generations after the administration of chlormadinone acetate and human chorionic gonadotropin]. / Untersuchungen zu Fruchtbarkeitsleistungen (Wurfmerkmale) von Labormäusen im Verlaufe von 6 Generationen nach Verabreichung von Chlormadinonacetat und Human chorionic gonadotropin.

Chlormadinone-acetate and human chorionic gonadotrophin (HCG) were tested for their action on fertility (litter parameters) through 6 generations of laboratory mice. The fertility parameters recorded were in no way indicative of any fertility-depressing effect. HCG acted positively on ovulation rates and also had a somewhat favourable impact on body weight development of the mice involved in testing.