Chronopharmacologic aspects of continuous AcSDKP infusion in mice.

Inconsistent results characterized N-acetyl-Ser-Asp-Lys-Pro (AcSDKP or Goralatide) effects upon hematologic proliferation, possibly because its circadian organization had been overlooked. We investigated the circadian changes in AcSDKP disposition in plasma and in bone marrow during continuous infusion and AcSDKP effects upon the circadian rhythms in bone marrow granulomonocytic precursors (CFU-GM) and circulating blood cell counts. One hundred ninety-six male B6D2F1 mice received a constant infusion of AcSDKP (24 microg/ day) or 0.9% NaCl for 7 days, using an osmotic minipump. All mice were synchronized with an alternation of 12 hours of light and 12 hours of darkness for 3 weeks prior to study. Mice were sacrificed on the fifth or seventh infusional day at 3, 9, 15, or 21 hours after light onset (HALO) in order to assess plasma and bone marrow AcSDKP concentrations, CFU-GM, and/or circulating blood cell counts. In control mice, plasma and bone marrow AcSDKP concentrations displayed a circadian rhythm with a maximum level during the dark span, at 21 and 15 HALO respectively, while CFU-GM, leukocyte, lymphocyte, and monocyte counts peaked during early light. Continuous AcSDKP infusion increased fivefold mean plasma AcSDKP level at 3 or 9 HALO, thus inverted its physiologic rhythm and suppressed the CFU-GM peak that normally occurs at these times. This inhibition however, was indirect, because the rhythms in bone marrow AcSDKP concentration were similar with or without AcSDKP infusion. Conversely, mean leukocyte and lymphocyte counts were significantly reduced with AcSDKP infusion, while their circadian rhythms remained unaffected and were amplified. The results indicate that AcSDKP pharmacology displays circadian rhythmicity and warrant the exploration of chronopharmacologic schedules of AcSDKP delivery for further protecting bone marrow against chemotherapy insults.

Electrochemotherapy on liver tumours in rabbits.

Electrochemotherapy (ECT) is a new therapeutic approach combining the effects of a low-permeant cytotoxic drug, bleomycin (BLM), administered i.v. and cell-permeabilizing electric pulses (EPs) locally delivered to tumours. The transient permeabilization of the cell membrane by the EPs allows free access of BLM to its intracellular targets, largely enhancing BLM's cytotoxic effects. ECT efficacy has been proved so far on transplanted subcutaneous murine tumours and on subcutaneous metastases in humans. Here, we present the first study of the effects of ECT on tumours transplanted to livers in rabbits. We used a recently developed EP applicator consisting of an array of parallel and equidistant needles to be inserted in tissues. Effects of EPs alone or of ECT were assessed by histological analysis, tumour growth rates and survival of the treated animals. A transient blood hypoperfusion was seen in the electropulsed areas, with or without BLM, related to EP-dependent vasoconstriction but this had no major effects on cell survival. Long-term effects depended on the presence of BLM at the time of EP delivery. Almost complete tumour necrosis was observed after ECT, resulting from both BLM direct cytotoxic effects on electropermeabilized tumour cells and indirect effects on the tumour vessels. A large reduction in tumour growth rate and significantly longer survival times were scored in comparison with control rabbits. Moreover, ECT of liver tumours was well tolerated and devoid of systemic side-effects. When ECT was associated with a local interleukin 2-based immunotherapy, increased local anti-tumour effectiveness as well as a large decrease in the number of metastases were observed. Thus, ECT could become a novel treatment modality for liver tumours and other solid internal malignancies.

Alterations of biological parameters in mice chronically exposed to low-frequency (50 Hz) electromagnetic fields.

In an experimental study we measured changes in hematological, biochemical and cortisol parameters in 6-week-old Swiss mice continuously exposed to ELF generated by a transformer station and high current bus bars. Mean daily exposure of 5.0 microT was maintained for 350 days. Hematological parameters were compared to those of control mice (n=12) exposed to a field level lower than 0.1 microT. Serum biochemical parameters (sodium, potassium, chloride, calcium, magnesium, phosphorus, amylase, creatine phosphokinase, and lactate dehydrogenase) were measured after 28 days of exposure and serum cortisol after 90 and 190 days. Granulocyte/macrophage colony-forming cells (GM-CFC) were counted at the end of the 350-day exposure. On day 20, exposed animals showed a significant decrease in leukocyte, erythrocyte, lymphocyte and monocyte counts and in hemoglobin and hematocrit values, while MCV increased. On days 43 and 63 no significant difference was observed in leukocyte and erythrocyte values, as if hemopoiesis had recovered. On day 90, a significant fall in the leukocyte, polynuclear neutrophil and eosinophil counts was observed in the exposed animals. No significant difference was noted in the biochemical parameters studied. On day 190, exposed animals had neutropenia and a decrease in the cortisol value. On day 350, no significant difference in hematological parameters was noted. Individual differences in sensitivity were observed, as 8 mice in the exposed group showed a significant decrease in the leukocyte, polymorphonuclear neutrophil and GM-CFC counts, while in two mice there was a significant increase in these same values compared to those unexposed mice.

The tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (Goralatide) protects from doxorubicin-induced toxicity: improvement in mice survival and protection of bone marrow stem cells and progenitors.

The tetrapeptide Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP or Goralatide), a physiological regulator of hematopoiesis, inhibits the entry into the S-phase of murine and human hematopoietic stem cells. It has been shown to reduce the damage to specific compartments in the bone marrow resulting from treatment with chemotherapeutic agents, ionizing radiations, hyperthermy, or phototherapy. The present study was performed to assess the therapeutic potential of AcSDKP in vivo in reducing both the toxicity and the hematopoietic damage induced by fractionated administration of doxorubicin (DOX), a widely used anticancer drug. Here we showed that AcSDKP could reduce DOX-induced mortality in mice and could protect particularly the long-term reconstituting cells (LTRCs) in addition to colony forming units-spleen, high proliferative potential colony-forming cells, and colony-forming units-granulocyte-macrophage (CFU-GM) from DOX toxicity. The protection against DOX-induced mortality in mice was improved when AcSDKP was administered for 3 days, at a dose of 2.4 micrograms/d, by continuous subcutaneous (SC) infusion or fractionated s.c. injections starting 48 hours before DOX treatment. Moreover, the recovery of the CFU-GM population in the AcSDKP-DOX-treated mice was optimized by the subsequent administration of granulocyte colony-stimulating factor (G-CSF). The coadministration of AcSDKP with DOX may improve its therapeutic index by reducing both acute hematotoxicity on late stem cells and progenitors and long-term toxicity on LTRCs. Optimization of these treatments combined with G-CSF may provide an additional approach to facilitate hematopoietic recovery after cancer chemotherapy.

Ethylenebisdithiocarbamates and ethylenethiourea: possible human health hazards.

Humans are exposed to ethylenebisdithiocarbamates (EBDCs) from environmental sources. Exposure to EBDCs is chronic for workers in a variety of industries, where EBDCs are used for their properties as slimicides, vulcanization accelerators, antioxidants, and scavengers in waste-water treatment. EBDCs, and particularly the EBDC metabolite ethylenethiourea, have clearly defined, important toxic effects in various animal species, and there is reason to suspect they are carcinogenic in humans. In the absence of definitive information regarding human risk, further studies need to be done. In the interim, regular surveillance of workers with high levels of exposure to EBDCs, with specific attention to markers of thyroid and hepatic pathology, should be considered.