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Dexrazoxane (DXR, ICRF-187) has been shown both in animal studies and clinical trials to provide a substantial cardioprotection when co-administered with anthracycline drugs like Doxorubicin (DOX). In a previous study, we showed that chronic DOX treatment in rats is associated with a clear impairment of the crossbridge kinetics and shift in myosin iso-enzymes. The present study was adopted to investigate whether the cardioprotective action of DXR involves preservation of the normal actin-myosin interaction. Rats were treated for 4 weeks with either DOX at a weekly dose of 2 mg kg−1 (i.v.), or were pre-injected with DXR (40 mg kg−1, i.v.) at a 20 : 1 dose ratio 30 min prior to the DOX infusion. Rats receiving saline or DXR alone were included in the experiments. Cardiac trabeculae were isolated 4 weeks after the last infusion and were skinned with detergent. Crossbridge turnover kinetics were studied after application of rapid length perturbations of varying amplitudes in Ca2+-activated preparations. DXR treatment offered a significant protection against the DOX-induced impairment of the crossbridge kinetics in isolated cardiac trabeculae. Time constants describing transitions between different crossbridge states were restored to normal in both the quick release protocol and the slack-test. DXR prevented the shift from the ‘high ATPase’ α-myosin heavy chain (MHC) isoform towards the ‘low-ATPase’ β-MHC isoform in the ventricles. We conclude that pre-administration of DXR in rats greatly reduces the deleterious effects of chronic DOX treatment on the trabecular actin – myosin crossbridge cycle. Preventing direct deleterious effects on the actin – myosin crossbridge system may provide a new target for preventing or reducing DOX-related cardiotoxicity and may enable patients to continue the treatment beyond currently imposed limits. British Journal of Pharmacology (2002) 135, 1707–1714; doi:10.1038/sj.bjp.0704621

Anthracyclines are highly effective anticancer agents which induce a well described but incompletely understood cardiac toxicity. In this study, a direct action of several anthracyclines on the force generating mechanism of heart muscle preparations is described. To allow discrimination between membrane related effects and a direct action of anthracyclines on the actin-myosin contractile system, both inner and outer membranes of cardiac fibres were permeabilized. All anthracyclines tested in this study [doxorubicin (Dox), epirubicin, daunorubicin and idarubicin] showed positive inotropic actions. Dox and epirubicin, which are considered the most cardiotoxic drugs of the anthracycline family, significantly increased the maximal calcium activated tension by 33% (n = 8, P < 0.01) and by 26% (n = 8, P < 0.01) respectively. Daunorubicin and idarubicin increased the maximal tension by 12% and 9% respectively (P = n.s.). Other chemotherapeutic drugs (Taxol and 5-FU) had no effect on maximal tension. To elucidate the mechanism behind this Dox-induced increase in maximal tension, calcium sensitivity curves were measured and rigor experiments were performed. A small but significant increase in pCa50 value (+0.14 +/- 0.03, P < 0.05) was observed only after incubation with 20 microM Dox. Dox acted during the transition to force generating cross-bridges as reflected by the significant increase in rigor tension (12%, P < 0.05) after preincubation of cardiac fibres with Dox. Cycling of cross-bridges is a prerequisite for Dox to increase tension because no effect on tension was seen after Dox was added to fibres in an established rigor. In summary, anthracyclines increased the maximal tension in cardiac muscle fibres by direct interaction with the actin-myosin cross-bridges. Changes in calcium sensitivity are unlikely to contribute to the observed increase in maximal tension. The rise in tension as is seen in this experimental set-up may contribute to destruction of the contractile machinery of cardiac muscle. In agreement with this hypothesis is the observation that the more cardiotoxic anthracyclines induced the largest increase in maximal tension of the cardiac fibres.

To investigate the role of neuropeptide Y (NPY) in the paraventricular nucleus of the hypothalamus (PVN) in the regulation of autonomic outflow, hormonal (plasma insulin and catecholamines), metabolic (blood glucose and plasma free fatty acids) and cardiovascular (heart rate and main arterial pressure) indices were measured before, during, and after bilateral infusion of NPY (1.0, 0.2, 0.04 micrograms in 1 microliter synthetic CSF) into the PVN of conscious resting rats. Administration of the highest dose (1.0 microgram/microliter) caused bradycardia and reduced circulating norepinephrine levels without effecting circulating fuels, insulin or epinephrine. In a second experiment, feeding-induced changes in hormonal and metabolic indices were assessed after NPY administration (1.0 microgram/microliter) into the PVN. During and after feeding, NPY enhanced the feeding-induced insulin response (P0.01) and attenuated the feeding-induced norepinephrine response (P0.05). The results of the present study suggest that stimulation of NPY receptors in the PVN decreases sympathetic activity and increases parasympathetic activity in resting conditions, and that these effects are potentiated during feeding.

I quattro livelli (tecnico-professionale in senso stretto, giuridico, deontologico e bioetico) nei quali si inscrive il rapporto medico-paziente comportano problemi diversi nel consenso informato e nelle prestazioni per la diagnosi e cura delle malattie fetali e di quelle del neonato. Di tali problemi, esaminati principalmente nell'ottica delle norme giuridiche e deontologiche italiane, gli autori tracciano le linee essenziali.

Doxorubicin, a very potent and often used anti-cancer drug, has a wide spectrum of biological activity. Classic studies have demonstrated that doxorubicin and other members of the anthracycline family intercalate with DNA and partially uncoil the double-stranded helix. Doxorubicin has a high affinity for cell nuclei: as much as 60% of the total intracellular amount of doxorubicin is found in the nucleus. Once binding to DNA occurs, several consequences may ensue. The binding of anthracyclines to DNA inhibits DNA polymerase and nucleic acid synthesis. In addition, anthracyclines are known to stabilize the otherwise cleavable complex between DNA and homodimeric topoisomerase II enzyme subunits, resulting in the formation of protein-linked DNA double strand breaks. In tumor cells, these anthracycline-induced perturbations are believed to result in a final common pathway of endonucleolytic DNA fragmentation known as apoptosis. Because proliferation is an important determinant of tumor growth, interference with the genome is regarded as the primary cause of the anti-tumor action of doxorubicin. Intercalation with DNA may not be important in the cardiotoxicity associated with doxorubicin therapy (see next section), because cardiac cell proliferation in humans stops after 2 months of age. This review is focussed on the effects of doxorubicin on mechanical performance in skinned cardiac trabeculae after acute and chronic administration of doxorubicin. We look especially at the mechanical performance and the molecular changes observed and related to mechanical performance.

The development of chronic cardiotoxicity in cancer patients treated with doxorubicin (DOX) and other anthracycline antineoplastic agents is a major dose-limiting factor. In a previous study, we demonstrated an acute effect of anthracyclines on the actin-myosin contractile system. Here, we report chronic effects of DOX both on the contractile system and on the function of the sarcoplasmic reticulum (SR). Male Wistar rats were treated with DOX (2 mg/kg, i.v., once a week for 4 weeks), whereas control rats received equal volumes of saline. Right ventricular trabeculae were isolated and skinned by exposure to Triton X-100 or saponin at 1, 2, 4, and 6 weeks after the final DOX administration. The maximal tension of trabeculae was similar between DOX-treated and control animals at 1 week posttreatment. At 2, 4, and 6 weeks posttreatment, the maximal tension of trabeculae of DOX-treated animals was significantly decreased by 27, 32, and 37%, respectively (P0.01). The rigor tension in trabeculae of DOX-treated animals was similar at 1 week posttreatment but significantly decreased at 2, 4, and 6 weeks posttreatment (by 25, 25, and 37%, respectively; P0.01). The ratio between rigor tension and maximal tension was significantly higher in DOX-treated groups as compared to controls (0.39 +/- 0.01 and 0.36 +/- 0.01; P0.05). Calcium sensitivity of DOX-treated preparations was significantly decreased as compared to controls (5.59 +/- 0.02 and 5.65 +/- 0.01; P0.05), whereas no effects were found on the cooperativity of the regulatory proteins, as measured by the Hill coefficient. The calcium release function of the SR, measured by caffeine (25 mM) stimulation in saponin-skinned trabeculae, was the same in DOX-treated and control groups at all posttreatment periods. The results of the present study show that long-term DOX treatment causes substantial impairment of the cross-bridge interaction in skinned trabeculae, which is reflected by a progressive attenuation of the contractile performance. The function of the SR, however, remains unaffected by DOX treatment in our preparations. The direct effect of chronic DOX treatment on the actin-myosin system provides an additional mechanism through which anthracyclines exert their cardiotoxic effects and may facilitate the development of cardioprotective strategies.

The bacteriocin produced by Streptococcus faecalis var. zymogenes (E-1) is most active against Diplococcus pneumoniae and least against other strains of S. faecalis. Clostridium perfringens showed an intermediate susceptibility to the active principle. By utilizing the gas production of C. perfringens as an indicator of metabolic activity, a decrease in sensitivity to bacteriocin was demonstrated with aging of the culture. Non-viable pinpoint clostridial colonies frequently developed by exposure of C. perfringens to a 2 or 3 hr old E-1 broth culture. The action of E-1 as studied on C. perfringens appears to be bactericidal and only partially bacteriolytic. The extent of E-1 bactericidal activity on susceptible D. pneumoniae, C. perfringens, and S. faecalis was shown to be dependent upon bacteriocin concentration.

High-risk premature infants require red cell transfusions for anemia. Placental blood for autologous transfusions can be collected sterilely into citrate-phosphate-dextrose and stored at 4 degrees C. During storage for 8 days, the placental red cell content of adenosine triphosphate remained normal. The 2,3,-diphosphoglycerate concentration of cells stored 8 days declined sharply; however, the P50 value of the oxyhemoglobin dissociation curve declined to 24.4 +/- 2.40 torr. During storage, placental blood underwent an exchange of extracellular Na+ and K+, but no change in glutathione content. Hemolysis was less than 1 percent. Bacteriologic and fungal cultures remained sterile. These in vitro studies suggest that human placental blood can be collected safely and preserved effectively for autologous red cell transfusion therapy.

Plasma levels of luteinizing and follicle-stimulating hormones were measured for 24 hours in six subjects affected by constitutional stature delay associated with sexual maturation delay. The children in pubertal stage exhibited fluctuating plasma concentrations of these hormones which significantly increased during sleep, as in healthy pubertal subjects. Thus in this type of delayed puberty, the synchronization of augmented gonadotropin secretion with sleep develops later in chronologic age but it is strongly related to bone age.

An open comparative study was carried out in 56 paediatric patients with acute upper and lower respiratory tract infections to assess the efficacy and tolerance of treatment with erythromycin, amoxicillin or co-trimoxazole. Patients were treated with the standard recommended doses for 7 to 10 days. Diagnoses included otitis, tonsillitis, pharyngitis, epiglottiditis, pertussis, scarlet fever and bronchitis and, when possible, pathogens were isolated and identified at the initial visit. The clinical findings showed that all three treatment resulted in statistically significant decreases in final mean values for temperature, pulse rate and respiration rate. Twenty of the patients with positive cultures on entry became negative by the end of treatment. No clinical side-effects, were reported with any of the treatments. Overall assessment of response and acceptability of treatment by physician and patient/parent indicated that erythromycin was at least equally as effective as the other two drugs in treating common respiratory diseases found in paediatric practice.

Many advances characterize the research into the diagnosis of short stature in children. Increasing evidence shows a continuous spectrum of growth hormone (GH) output among GH-deficient patients and short normal children. Although biosynthetic human GH could theoretically offer the chance of treating most slowly growing children, it is not certain that all short normal children with a poor height velocity could benefit from therapy. Indeed, besides auxological findings, the assessment of GH secretion remains essential in selecting candidates for therapy. In this respect the evaluation of GH secretion by means of tests that can explore the physiological pathways involved in the hormone output appears important. Moreover some clinical evidence suggests that pharmacological stimuli cause the pituitary release of stored GH perhaps unavailable in physiological conditions. Among the classical physiological tests, the exercise test, the standardization of which has been debated, is commonly used in clinical practice. The sleep test, i.e. the evaluation of sleep-associated GH secretion, is the most important. It has no side effects and does not require the administration of exogenous stimuli. Several studies have demonstrated its reliability in diagnosing growth disorders in childhood, mainly if performed with EEG monitoring. Among the new physiological diagnostic approaches the most reliable test is the evaluation of 24-hour GH secretion. Knowledge of the integrated hormone concentrations appears particularly important in studying children who may have more subtle disturbances in GH secretion. These cases show normal GH response to provocative stimuli but show a reduced hormone output over 24 h. Indeed they respond well to human GH treatment.

The rarity of acute lymphoblastic leukemia in association with hypereosinophilia justifies the communication of this new case; as the eosinophilia preceded the diagnosis, our case emphasizes observation and checking them regularly.