Electrochemotherapy of mouse sarcoma tumors using electric pulse trains with repetition frequencies of 1 Hz and 5 kHz.

Electrochemotherapy is an efficient local treatment of tumors that combines administration of a chemotherapeutic drug with the subsequent application of electric pulses to the tumor. Although no difference in clinical response of the treated tumors to the electrochemotherapy when using 1 Hz or 5 kHz repetition frequency was observed, it is mandatory to be aware of possible differences in the effectiveness of electrochemotherapy when using suboptimal doses of the drugs. Therefore, this study compares the antitumor effectiveness of electrochemotherapy using electric pulse trains with repetition frequencies of 1 Hz and 5 kHz at suboptimal drug doses of bleomycin or cisplatin. Electrochemotherapy of fibrosarcoma SA-1 subcutaneous tumors transplanted in A/J mice resulted in good antitumor effectiveness, but antitumor effectiveness was significantly better at 1 Hz repetition frequency than at 5 kHz. The platinum content was higher in tumors treated with a 1 Hz repetition frequency. The application of electric pulses to the tumors at a 5 kHz repetition frequency induced an immediate reduction in tumor perfusion, comparable to the reduction at 1 Hz but with faster reperfusion. The greater effectiveness of electrochemotherapy using electric pulse trains of 1 Hz compared to 5 kHz is due to the greater electroporative effect and longer time in which electroporated tumors are exposed to the two chemotherapeutic drugs. These differences are observed at suboptimal drug doses, whereas at optimal drug doses of bleomycin or cisplatin the antitumor effectiveness is the same, as demonstrated in clinical trials.

Serotonin regulation of nerve growth factor synthesis in neonatal and adult astrocytes: comparison to the beta-adrenergic agonist isoproterenol.

Although serotonin regulates synthesis of the neurotrophic factor S-100 beta by astrocytes, its ability to affect nerve growth factor (NGF) synthesis has never been examined. We report here that there is a correlation between the effect of serotonin on cyclic adenosine monophosphate (cAMP) content and on NGF content in neonatal astrocytes but not in adult astrocytes. In neonatal striatal astrocytes, serotonin increases both cAMP and NGF, whereas, in neonatal cerebellar astrocytes, serotonin decreases both. The increase in neonatal cortical astrocyte cAMP appeared to be too small (45%) to increase NGF significantly. The beta-adrenergic agonist isoproterenol increased cAMP and NGF in both cortical and striatal astrocytes derived from neonatal rats. In contrast, there was a dissociation between cAMP changes and NGF changes in astrocytes derived from adult rats. Both serotonin and isoproterenol increased cAMP in adult cortical astrocytes, without any effect on NGF content. However, adult striatal astrocytes responded to serotonin with an elevation of both cAMP and NGF, whereas isoproterenol could only enhance cAMP, without affecting NGF. Thus, in neonatal astrocytes, a change of sufficient magnitude in cAMP was correlated with a comparable change in NGF, in response to activation of either serotonergic or beta-adrenergic receptors; in cerebellar astrocytes, the decrease in cAMP was accompanied by a decrease in NGF. In contrast, adult astrocytes were not responsive: Although cAMP changes were large, NGF synthesis was increased only in striatal astrocytes and only in response to serotonin. J. Neurosci. Res. 64:261-267, 2001. Published 2001 Wiley-Liss, Inc.

Prognostic value of motor evoked potentials elicited by multipulse magnetic stimulation in a surgically induced transitory lesion of the supplementary motor area: a case report.

Surgery involving the supplementary motor area (SMA) places the patient at risk of transient motor deficit. To predict outcome in patients with early postoperative hypokinesis would be relevant to both the patient and the surgical team. A 15 year old girl with a large left thalamic tumour removed through a left transcallosal approach is described. Despite intraoperatively preserved muscle motor evoked potentials (mMEPs) from all limbs, elicited by multipulse electrical stimulation, she awoke with a right hemiplegia and mutism. On the first postoperative day, neurophysiological evaluation using a multipulse magnetic stimulation technique, with a train of four magnetic stimuli, confirmed the presence of mMEPs from the hemiplegic right limbs. Slight spontaneous motor activity of the right limbs and initial speech were seen later on the same day with dramatic improvement over subsequent days. It is concluded that multiple rather than single magnetic stimulation techniques may be needed to elicit mMEPs for an early postoperative differential diagnosis of SMA damage versus injury to the primary motor cortex or the corticospinal tract.

Cytokine-regulated secretion of nerve growth factor from cultured rat neonatal astrocytes.

Interactions involved in the regulation of nerve growth factor (NGF) release by inflammatory cytokines: interleukin-1beta (IL-1beta), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) were examined in rat neonatal cortical astrocytes in primary culture. Exposure of cultured astrocytes to IL-1beta, IL-6, and TGF-beta1 resulted in the stimulation of NGF secretion. Treatment of cells for 24 h with IL-1beta (10 U/ml), IL-6 (5 ng/ml) and TGF-beta1 (5 ng/ml) caused 3-, 1.8-, and 2.8-fold increase in NGF secretion as compared to the control cells. In contrast, TNF-alpha (30 ng/ml) by itself had no stimulatory action on NGF release whereas co-stimulation of astrocytes with IL-1beta and TNF-alpha showed a synergistic interaction. Co-treatment of astrocytes with IL-1beta and TGF-beta1 increased NGF secretion in an additive way, whereas simultaneous application of IL-1beta and IL-6 resulted in the inhibitory effect on NGF secretion. Our results suggest that interactions between cytokines used cause the stimulation of NGF secretion through different regulatory mechanisms.

The effects of histamine and interleukin-6 on NGF release from cortical astrocytes in primary culture.

The influence of neurotransmitter histamine and cytokine interleukin-6 (IL-6) on nerve growth factor (NGF) release was studied in rat neonatal cortical astrocytes in primary culture. Exposure of astrocytes to either histamine or IL-6 resulted in the stimulation of NGF release. Maximal stimulation of NGF release was obtained using histamine at concentration 100 nM after 24 h of treatment (2.3 fold increase over the basal secretion from the control cells). IL-6 (30 ng/ml) induced NGF secretion was 1.66 fold over the basal level. Time course of NGF release, after histamine or IL-6 treatment, showed elevation of NGF level in the culture medium after 8 h or 24 h, respectively. IL-6 antibody effectively blocked the IL-6 stimulatory effect on NGF release, but did not influence NGF release, evoked by histamine. IL-6 antibody alone did not show any influence on NGF release. Our results suggest that IL-6 and histamine stimulate release of NGF by two different and independent molecular pathways.

PSA-NCAM distinguishes reactive astrocytes in 6-OHDA-lesioned substantia nigra from those in the striatal terminal fields.

6-hydroxydopamine (6-OHDA) lesion of the substantia nigra (SN) causes the appearance of reactive astrocytes not only in the SN but also in the striatal terminal fields, as measured by increased size of the cells and their processes, as well as enhanced expression of glial fibrillary acidic protein (GFAP) and an epitope recognized by monoclonal antibody 19D1. We now demonstrate that polysialylated neural cell adhesion molecule (PSA-NCAM) is induced on reactive astrocytes, as well as on large neurons, on the ipsilateral side of the 6-OHDA-lesioned SN. Colocalization of GFAP and PSA-NCAM was confirmed for reactive astrocytes using a confocal laser scanning microscope. Negligible amounts of PSA-NCAM reactivity were detected contralaterally, although colocalization was noted on astrocytes with sparse, significantly thinner processes. In contrast to the increase of GFAP in the lesioned striatum, few striatal astrocytes expressed PSA-NCAM. In agreement with these results, PSA-NCAM was detected on cultured reactive astrocytes from SN but not reactive striatal astrocytes. Double immunohistochemistry for proliferating cell nuclear antigen (PCNA), a marker of dividing cells, and GFAP demonstrated that reactive astrocytes in lesioned SN were PCNA-positive whereas those in striatum were not. Although NG2 chondroitin sulfate proteoglycan expression also increased in the lesioned SN, NG2 was not colocalized with PSA-NCAM, was not expressed on astrocytes, and labeled only oligodendrocyte precursor cells. Our results suggest that PSA-NCAM can act as a marker for reactive astrocytes only at the site of the lesion and not in the terminal fields, probably because it is reexpressed only when astrocytes divide.