Human cell membrane oxidative damage induced by single and fractionated doses of ionizing radiation: a fluorescence spectroscopy study

Purpose: To investigate the production and repair of lipid oxidative damage in two human cell lines exposed to acute and fractionated dose of ionizing radiation. Radiation dose was in the range from 0.1 to 44Gy. Materials and Methods: K562 and HL60 human cell lines have been used, 24 and 96 h after seeding. Membrane lipid oxidative damage has been detected by the measurement of the fluorescence decay of 1,6-diphenyl-1,3,5-hexatriene (DPH), its polarization value and the conjugated dienes concentration. The modification of DPH decay has been previously reported to be directly related to the lipid hydroperoxide concentration. Results: A modification of the DPH decay has been observed as a linear function of the logarithm of the radiation dose and only when the irradiation was performed in the presence of oxygen. The amount of the damage is related to the time after the cell medium change. By exposing the cells to fractionated radiation doses for several days (10 cGyday- 1), the oxidative damage has been found to be cumulative. After a single acute dose, evidence of repair of the lipid oxidative damage was not obtained. Conclusions: Following a previously developed method, the membrane damage was attributed to the production of hydroperoxide residues in the lipid acyl chains with the consequence of water penetration into the external portion of the bilayer, from the aqueous environment to the position of hydroperoxides. This damage is not repaired. The results obtained by measuring the DPH fluorescence decay have been compared with those obtained using other current optical and biochemical methods. None of these techniques could detect membrane oxidative damage at doses 10 Gy. Finally, the different sensitivity of 'young' and 'old' cells to the oxidative damage can be related to different cholesterol concentrations.     

SLEEP-WAKE PATTERNS AND INTEGRATED VALUES OF LUTEINIZING HORMONE, FOLLICLE STIMULATING HORMONE, PROLACTIN, GROWTH HORMONE AND THYROID STIMULATING HORMONE IN NORMAL AND CRYPTORCHID PUBERTAL PATIENTS

The sleep-wake behaviour of LH, FSH, PRI, GH and TSH was studied in seven cryptorchid patients (four unilateral and three bilateral cryptorchids) average age 12 years and in nine normal pubertal boys of 13 years (mean age). Blood samples were collected by a continuous withdrawal pump, every hour, for 24 h. The hormonal concentration for every fraction of time was measured and related to the sleep (Sc-), wake (Wc-) and total 24 h period (Dc-). The integrated concentrations of the corresponding periods (IS, IW, ID) were calculated as well as their ratios (IS/IW; IS/ID%). For GH and TSH, the data obtained demonstrated no differences between cryptorchid and pubertal subjects. The PRL secretion in cryptorchid patients was moderately increased during the hours of nocturnal sleep. A normal pubertal sleep-wake rhythm was found for gonadotrophins in both groups of subjects. More marked levels of LH secretion were observed in cryptorchid boys compared to normal pubertals. The presence of a sleep-wake rhythm was also found in the cryptorchid patients and normal pubertal subjects in the P 1 stage. These data suggest that the CNS "programme" which controls the onset of puberty may be normal in cryptorchid patients.     

Lack of effect of desmopressin on ACTH and cortisol responses to ovine corticotropin-releasing hormone in anorexia nervosa

Abstract. Both arginine vasopressin (AVP) and corticotropin-releasing hormone (CRH) are involved in the release of ACTH in man. Desmopressin (DDAVP), a synthetic analogue of AVP, has been shown to have a CRH-like action (able to promote ACTH and cortisol release) in animals but not in normal man. Nevertheless, DDAVP is able to release ACTH and cortisol in ACTH-dependent Cushing's disease. We studied eight anorexia nervosa (AN) patients [as AN is a condition in which chronic activation of the hypothalamic-pituitary-adrenal (HPA) axis is commonly reported] in a refeeding phase of the disease, to evaluate whether, after weight gain, ACTH and cortisol response to ovine corticotropin-releasing hormone (oCRH) [1 μg kg^-1 body weight (BW) i.v.] is restored. We also wanted to ascertain the effect on the HPA axis of 10 μg i.v. DDAVP alone and as pretreatment to oCRH (1 μg kg^-1 BW i.v.)-induced secretion of ACTH and cortisol. We studied six normal women as control subjects. No significant differences in ACTH and cortisol responses to oCRH were found between AN patients and control subjects. DDAVP was not able to stimulate ACTH or cortisol release in AN patients or in control subjects, but in the latter it was able to significantly enhance (P < 0.05) ACTH [area under curve (AUC): 590.0± 104.4 pmol L^-1 120 min^-1 and cortisol (AUC: 28899.0 ± 6935.2nmol L^-1 120 min^-1) responses to oCRH (ACTH AUC: 325.7 ± 101.7 pmol L^-1 120 min^-1, cortisol AUC: 14197.4 ± 2930.0 nmol L^-1 120 min^-1). The present data show that DDAVP does not stimulate ACTH and cortisol in AN patients or, as previously reported, in normal subjects. However, DDAVP is able to enhance ACTH and cortisol release after oCRH administration in normal subjects but not in AN patients. This finding could be due to a down-regulation of hypophyseal DDAVP V3 receptors in AN as a direct consequence of the hypercortisolaemic status usually present.     

PLASMA ANDROGENS IN WOMEN WITH HYPERPROLACTINAEMIC AMENORRHOES

Cortisol, androstenedione, testosterone, dehydroepiandrosterone sulphate (DHAS) and free dehydroepiandrosterone (DHA) were measured in plasma of ten women affected by amenorrhoea with hyperprolactinaemia and eleven women affected by secondary hypothalamic amenorrhoea; twelve normal women at the second day of the menstrual cycle were used as controls. All subjects were hospitalized and 17-ketosteroids, 170H-corticosteroids and total dehydroepiandrosterone were also measured in urine. Plasma DHAS was increased in all subjects affected by amenorrhoea with hyperprolactinaemia, while plasma DHA and urinary DHA were significantly increased in this group in comparison to other groups. Plasma cortisol, androstenedione and testosterone and urinary 17-oxosteroids and 170H-corticosteroids were not significantly different in the three groups. In subjects affected by amenorrhoea with hyperprolactinaemia treated with bromocriptine a clear decrease of DHAS correlating with a decrease of plasma prolactin was observed. Since in women DHAS seems to be almost exclusively secreted by the adrenal gland and most of the circulating DHA is derived from adrenal secretion, these data suggest that human prolactin can stimulate DHAS production by the adrenal cortex.     

Respiratory depression following administration of low dose buprenorphine as postoperative analgesic after fentanyl balanced anaesthesia

Opioids are among the most ancient and widely used drugs in anaesthesiology. The pharmacology of opioid analgesics and their receptors is a complex and not fully understood matter; even more complex are the interactions between different classes of opioids at both molecular and clinical levels. We want to report here a clinical observation to emphasize the importance of the theoretical basis of anaesthesiology. This paper contains a clinical observation of respiratory depression following the administration of buprenorphine as postoperative analgesic after balanced anaesthesia with fentanyl. The observed case is interpreted in the light of the pharmacokinetics and pharmacodynamics of the different classes of opioid drugs (agonists, agonists–antagonists, antagonists) and of the interactions with their respective receptors.