Reversibility of thymulin production impairment by L-arginine supplementation in mice exposed to inorganic mercury.

Immunotoxicological effects fo mercury on peripheral immune system are known. We had previously in vitro found that mercuric chloride inhibits thymulin production in mouse thymus cultures at concentrations as low as 10(-8) M. In this study, thymus efficiency, assessed as production of active and total thymulin, was evaluated in vivo using young mice that were injected sc every 3 days for 4 weeks with saline containing mercuric chloride at different concentrations (0 -controls-, 0.001 or 1.0 mg HgCl2/kg body weight). The results show that both the doses are able to cause a significant reduction in active and total thymulin production. Since arginine enhances immune efficiency some of the animals also received a diet supplemented with arginine in order to evaluate a possible role of arginine during mercury intoxication. The data show that arginine has a protective effect on thymic endocrine efficiency. Mice, treated with the lowest dose of mercury and receiving and arginine supplemented diet, produced active and total thymulin like mercury untreated mice. Arginine is an aminoacid which may be found in various amounts in different foods, some foods are particularly rich in arginine i.e. peanuts, stock fish. We suggest that the daily arginine intake may account for individual susceptibility to the mercury-induced immunological effects which are found in mercury occupationally exposed workers.

Elevation of extracellular glutamate in the final, ischemic stage of progressive epidural mass lesion in cats.

Epidural mass lesions may cause ischemia due to progressive intracranial hypertension. In order to investigate the impact of intracranial pressure on accumulation of neuroactive substances, we gradually raised intracranial pressure in five halothane anesthetized cats by inflation of an epidural balloon. We evaluated in the parietal cortex contralateral to the site of balloon inflation, alterations of extracellular glutamate and purine catabolites and of the lactate/pyruvate ratio in relation to changes of intracranial, cerebral perfusion and mean arterial blood pressure. In a complementary experiment, regional cerebral blood flow was assessed by sequential positron emission tomography. In this simplified mass lesion model, extracellular glutamate increased in all cats at a late, critical stage after tentorial herniation, when intracranial pressure had increased to more than 90 mm Hg, cerebral perfusion pressure had decreased below 40-50 mm Hg. Positron emission tomography assessments revealed that the ischemic threshold for glutamate accumulation was in the range of 15-20 mL/100 g/min. Purine catabolites and the lactate/pyruvate ratio increased somewhat earlier than glutamate, but also after reaching the critical, terminal stage. We conclude that in this model of progressive epidural compression, glutamate-mediated excitotoxic processes at sites remote from the initial focal lesion depend on processes such as delayed ischemia in combination with tentorial herniation and systemic hypotension. These processes seem to be initiated by a decrease of cerebral perfusion pressure below a threshold of 40-50 mm Hg.

Generation of a transcription map of a 1 Mbase region containing the HFE gene (6p22).

A transcription map was generated of a 1 Mb interval including the HFE gene on 6p22. Thirty-seven unique cDNA fragments were characterised following their retrieval from hybridisation of immobilised YACs to primary pools of cDNAs prepared from RNA of foetal brain, human liver, foetal human liver, placenta, and CaCo2 cell line. All cDNA fragments were positioned on the physical map on the basis of presence in aligned and overlapping YACs and cosmid clones of the region. The isolated cDNAs together with established or published sequence tagged sites (STSs) and markers provided sufficient landmark density to cover approximately 90% of the 1 Mb interval with cosmid clones. The precise localisation of two known genes (NPT1 and RING finger protein) was established. A minimum of 14 additional transcription units has also been integrated. Twenty-eight cDNA fragments showed no similarity with known sequences, but 20 of these detected discrete mRNAs upon northern analysis. Their characterisation is still under investigation. Eleven new polymorphisms were also identified and localised, and the HFE genomic structure was better defined. This integrated transcription map considerably extends a recently published map of the HFE region. It will be useful for the identification of genetic defects mapping to this region and for providing template resources for genomic sequencing.

[Hyperlipidemia findings in workers in an oil refinery]. / Rilievo di iperlipidemie in operai di una raffineria di petrolio.

During a cross sectional epidemiologic study the cholesterol and triglyceride plasmatic levels were measured in 207 workers employed in an oil refinery. Our results show high levels both for cholesterol and triglyceride. Emphasis has been laid on the serious dietary and hygienic problems for these workers. The finding of hyperlipidemia as well as obesity and over-weight do not seem to be related to exposure to any occupational chemical hazard.