Acute effect of callosotomy on cortical temporal coupling in humans: intraoperative electrocorticographic recording.

OBJECTIVE: To investigate the acute role of the corpus callosum in inter- and intrahemispheric temporal coupling. METHODS: Intraoperative electrocorticography (ECoG) makes it possible to investigate the acute role of the corpus callosum in cortical temporal coupling, or synchrony, without additional surgical intervention, thus avoiding the confounding effects of scalp recordings and the long-term reorganization of functional connectivity. ECoGs were recorded in three patients during callosotomies. Bilateral electrode grids were placed over the frontal cortex. ECoGs were recorded immediately before and after performing the anterior two-thirds callosal transection, were digitalized at a sampling rate of 512Hz, inspected for artifacts, and later analyzed offline. Cross-correlation between inter- and intrahemispheric electrode pairs were obtained for 1Hz bins and special broad bands obtained by principal component analysis for each patient pre- and post-callosotomy. RESULTS: A statistically significant change was observed in intrahemispheric temporal coupling between electrode pairs that exceeded the confidence limit of correlation. CONCLUSIONS: Present results show that interrupting the influence of the corpus callosum has an acute effect on intrahemispheric activity by decreasing temporal coupling between cortical areas. SIGNIFICANCE: Intrahemispheric temporal coupling does not depend exclusively on ipsilateral cortico-cortical pathways or on subcortical influences, but also on callosal pathways.

Drug targets from human pathogenic amoebas: Entamoeba histolytica, Acanthamoeba polyphaga and Naegleria fowleri.

In this review we present our search for the presence of drug targets in several species of human pathogenic parasites, mainly the amoebas Entamoeba histolytica, Acanthamoeba polyphaga and Naegleria fowleri. We started with an analysis of the concepts of essentiality and validity of the targets and continue with a description of the main characteristics of pathogenicity of these amoebas. We then proceed to evaluate these targets arranged mainly in seven groups corresponding to: a) enzymes which are secreted by these parasites to invade the human host, for example proteinases, phospholipases and pore forming peptides, b) glycolytic enzymes from Entamoeba and Naegleria, like the PPi-dependent phospho-fructokinase that differ from the host enzyme, c) thiols and enzymes of redox metabolism, present only in trypanosomatids, Entamoeba and Naegleria, such as the trypanothione/trypanothione reductase that maintains the reducing environment within the cell, d) antioxidant enzymes to regulate the oxidative stress produced by the phagocytic cells of the host or by the parasite metabolism, like the trypanothione peroxidase in connection with the NADPH-dependent trypanothione/trypanothione reductase which maybe is present in Naegleria fowleri, and peroxiredoxin in E. histolytica, e) enzymes for the synthesis of trypanothione like the ornithine decarboxylase, spermidine synthase and trypanothione synthetase, f) some of the proteins that assemble the secretory vesicles with the cell membrane, like the synaptobrevins and finally, g) encystment pathways and cyst-wall assembly proteins. Some of the above new targets will need to be studied in a more detail, including crystallographic studies of the enzymes for rational drug design. As far as we know there are no advanced crystallographic studies being conducted on targets from these three amoebas, as has been the case for various targets from the trypanosomatids.

Role of corpus callosum in interhemispheric coherent activity during sleep.

OBJECTIVE: To investigate to what extent the increase in interhemispheric coherent activity observed from wakefulness to sleep depends on the integrity of the corpus callosum (CC). METHODS: Interhemispheric coherent activity was analyzed in two epileptic patients selected for callosotomy because of multifocal refractory epilepsy, before and 4 months after callosotomy. One patient underwent complete callosotomy and another was subjected to callosotomy of the anterior 2/3, which offered the possibility of comparing the role of the CC in the coherent activity increase from wakefulness to sleep, between anterior regions with interrupted CC communication (in the two patients) and posterior regions with intact communication (in one of them). Results were compared with a group of normal subjects. RESULTS: Both patients showed increased coherent activity from wakefulness to sleep after surgery. CONCLUSIONS: Results demonstrate that interhemispheric coherent activity, despite an attenuation after surgery, is higher during SWS than during wakefulness after sectioning the CC; however, they have to be taken with caution because they come from two patients only. SIGNIFICANCE: Present results show that the increase in coherent activity during sleep does not depend exclusively on callosal integrity but also on state-dependent influences from sleep-promoting mechanisms, probably spread throughout the thalamo-cortical network.

Radiation resonance emission from steep overcritical plasma profiles illuminated by femtosecond laser pulses.

A radiation resonance effect observed in the reflection spectra from overdense plasmas illuminated by femtosecond laser pulses at normal incidence is reported from particle-in-cell simulations. Harmonic emission at multiple orders of the fundamental is found to exhibit resonance phenomena, with the number of resonances and power emitted depending on the electron plasma density. For relatively low laser intensities the reflected light at the laser frequency shows prominent resonant emission around specific values of the plasma density, mainly at 4, 16, and 36 times critical. For increasing laser intensities, strong harmonic emission around 4 and 16 times critical dominates the reflection spectra. In the case of the third laser harmonic, the emission is found to be resonant about those densities and presents, additionally, a distinctive resonant region around nine times critical. A simple radiation model for the power of the third harmonic was proposed confirming a resonant effect dependent on the electron plasma density. For higher harmonic numbers, weak radiation resonances persist in the emission spectra, with their number increasing with order. The resonance effect reported in this paper is found to occur at densities that approximately satisfy n(e)/n(c)=4n(2), where n(e) and n(c) are the plasma and the critical density, respectively, and n is an integer. For the third harmonic, the second resonance corresponds to n=1.5.

Progesterone receptor isoforms expression pattern in human astrocytomas.

Progesterone receptors (PR) have been detected in human astrocytomas; however, the expression pattern of PR isoforms in these brain tumors is unknown. Progesterone receptor isoforms expression was studied in 13 biopsies of astrocytomas (6 grade III, and 7 grade IV) from adult Mexican patients by using reverse transcription-polymerase chain reaction and immunohistochemistry. Progesterone receptor expression was observed at mRNA and at protein levels in 66% and 83% of astrocytomas grade III, respectively, whereas 100% of astrocytomas grade IV expressed PR. Almost all PR mRNA content in astrocytomas grades III and IV corresponded to PR-B. The number of immunoreactive cells expressing PR-B was higher than that expressing PR-A in 73% of the cases. Estrogen receptor-alpha protein was only observed in 33% of astrocytomas grade III, whereas no astrocytomas grade IV expressed it. These data suggest that PR-B is the predominant isoform expressed in human astrocytomas grades III and IV, and that estrogen receptor-alpha is not expressed in astrocytomas grade IV.

Progesterone receptor isoforms expression pattern in human chordomas.

Steroid hormone receptors are involved in the regulation of tumor growth. Two progesterone receptor (PR) isoforms have been identified in humans: a larger form (PR-B) and the N-terminally truncated one (PR-A). PR isoforms can exert opposite functions and are differentially regulated by estrogens. PR have been detected in several brain tumors including chordomas, however, it is unknown which PR isoform is expressed in brain tumors. The aim of this study was to determine by reverse transcription-polymerase chain reaction (RT-PCR) and by immunohistochemistry the expression pattern of PR isoforms in chordomas as well as its correlation with the expression of estrogen receptor a (ER-alpha). All studied chordomas expressed both PR and ER-alpha. PR-B was the predominant isoform in chordomas both at the mRNA and at the protein level. These data suggest that PR-B should be the predominant PR isoform expressed in human chordomas.

Characterization of benzodiazepine receptor binding in immature rat brain after kainic acid administration.

PURPOSE: To evaluate the effects of status epilepticus on benzodiazepine (BDZ) receptor binding in immature rat brain. METHODS: Twenty-four immature (15 days old) and six adult (90 days old) rats were used in this study. Status epilepticus was induced in immature animals by administration of kainic acid (7 mg/kg intraperitoneal), whereas adults rats received saline. Animals were killed 72 hours or 35 days after treatment, and their brains were used for in vitro autoradiography experiments to determine BDZ binding. RESULTS: In basal conditions and compared with the adult group, immature animals presented reduced BDZ binding in the entorhinal cortex, substantia nigra pars reticulata, and periaqueductal gray. Seventy-two hours after kainic acid-induced status epilepticus, immature rats showed significantly increased BDZ in the frontal (48%), cingulate (39%), sensorimotor (39%), piriform (57%), and entorhinal (59%) cortices, the medial (84%) and basolateral (27%) amygdaloid nuclei, the dentate gyrus (51%), and the substantia nigra pars reticulata (43%). Thirty-five days after status epilepticus, immature rats displayed decreased BDZ binding in the entorhinal cortex (48%), dentate gyrus (36%), and fields CA1, CA2, and CA3 of Ammon's horn (30%). CONCLUSIONS: The present study demonstrates that status epilepticus and temporal lobe epilepsy produce a characteristic pattern of BDZ binding changes in the immature rat brain that differs from the one previously seen in adults.

Inhibitory and lytic effects of phenothiazine derivatives and related tricyclic neuroleptic compounds, on Entamoeba histolytica HK9 and HM1 trophozoites.

It has been shown previously that tricyclic neuroleptics like clomipramine and chlorpromazine have lethal effects on Leishmania donovani and L. major, and other studies indicate that the phenothiazine inhibitors of trypanothione reductase are potential anti-trypanosomal and anti-leishmanial drugs. With this in mind and our original observation on the presence of trypanothione in Entamoeba histolytica HK9, we examined the possible inhibitory effects of various phenothiazine and tricyclic derivatives on this human parasite. We found that drugs like clomipramine (KD002), the most potent in vitro inhibitor of trypanothione reductase among 30 tricyclic compounds tested, at 25 microM after 24 h of culture under aerobic conditions, caused a substantial decrease in the number of E. histolytica HK9 trophozoites, from approx. 15 x 10(6) to 5.37 x 10(6) cells, and at 100 microM to 0.8 x 10(6) cells. A substantial inhibitory effect on cell proliferation could also be demonstrated with metronidazol (used clinically against amoebiasis). Under similar experimental conditions other tricyclic and phenothiazine derivatives (OFKs), designed originally to inhibit the trypanothione reductase of trypanosomatides, had an inhibitory effect of 16 to 95%. For comparison, similar results were obtained using clomipramine and a phenothiazine derivative (OFK006) with Trypanosoma cruzi and Crithidia luciliae, except that with the latter the inhibitory effect of clomipramine was less dramatic. Experiments comparing two E. histolytica strains showed that normal cell proliferation under anaerobiosis was higher in strain HK9 than in HM1, which is highly virulent, but that metronidazol and clomipramine were less effective against HM1. Two other drugs tested, diphenydramine (KD005) and a phenothiazine derivative (OFK008), also had significant but lower inhibitory effects on both strains. The inhibitory activity on cell proliferation and the lytic effects on this human parasite by the tricyclic compounds clomipramine, chlorpromazine and others, as well as by the phenothiazine derivatives, indicate that they can be considered potential anti-amoebic agents.

Detection by HPLC of a trypanothione synthetase activity in vitro from Entamoeba histolytica.

We have previously demonstrated the presence of glutathione-spermidine (Gsp) and trypanothione [T(SH)(2)] from Entamoeba histolytica trophozoites, on the basis of results obtained with acid extracts purified by Florisil and DEAE-cellulose, derivatized with the fluorescent reagent monobromobimane and separated by HPLC. Gsp was originally found in Escherichia coli and later in trypanosomatids such as Trypanosoma cruzi, T. brucei, T. congolense and the insect trypanosomatid Crithidia fasciculata, along with the novel compound T(SH)(2), N(1), N(8)-bis(glutathionyl)-spermidine. Here we demonstrate the presence of a T(SH)(2) synthetase activity in partly purified extracts from Entamoeba histolytica HK9, incubated at two pH values (6.5 and 7.5) with reduced glutathione (GSH), spermidine and ATP, in the presence of Mg(2+) at different time intervals. The thiol products were detected by HPLC in picomole amounts and compared with commercial Gsp and T(SH)(2) standards. We have used also an extract of Crithidia luciliae as a reference, to compare our results with C. fasciculata, in which the presence of this enzyme has previously been demonstrated and was later purified and separated into two synthetase activities from the same source: one for Gsp and the other for T(SH)(2). The presence of a T(SH)(2) synthetase activity in Entamoeba histolytica means that this protozoan has a similar metabolism to that of the trypanosomatids and opens the possibility of establishing a rational drug design against this human parasite.

Entamoeba histolytica: a eukaryote with trypanothione metabolism instead of glutathione metabolism.

Entamoeba histolytica is a human pathogen that lacks the capacity to synthesize glutathione but can incorporate it, from the growth media or presumably from the human host, to form trypanothione [N(1), N(8)-bis(glutathionyl)-spermidine conjugate]. This novel thiol compound has previously been found in trypanosomatids, as has its precursor glutathionyl-spermidine, which was originally detected in Escherichia coli. Previously we showed the presence of these two thiol compounds in extracts from cultures of Entamoeba histolytica HK9. Here we report that when Entamoeba histolytica HK9 is grown in a culture medium that lacks glutathione (treated with the enzyme gamma-glutamyl transpeptidase), trypanothione is not formed, although the trophozoites can continue dividing for at least 60 h but at 25% lower cell density. The finding of a trypanothione metabolism in Entamoeba histolytica raises many questions: one concerns the possibility of a phylogenetic relationship, in this respect, with trypanosomatids such as Trypanosoma cruzi, T. brucei and Crithidia fasciculata; another concerns its role in cell metabolism; a third concerns it possible use as a target for a rational drug design strategy against this parasite.

Antisense oligonucleotides to C-fos reduce postictal seizure susceptibility following fully kindled seizures in rats.

In a previous study we demonstrated that increased FOS expression in the amygdala induced by partial kindling seizures could be attenuated by administering c-Fos specific antisense oligonucleotides. In addition, we found that the administration of c-Fos antisense oligonucleotides at the beginning of the amygdala kindling process facilitated the appearance of stage V kindled seizures. In the present study, we evaluated the effect of the suppression of FOS on the expression and severity of the generalized fully kindled seizures as well as on the susceptibility to additional ictal events during the postictal and interictal periods. We observed that the administration of c-Fos antisense oligonucleotides did not modify the behavioral and electrographic manifestations of generalized stage V kindled seizures. However, c-Fos antisense oligonucleotides significantly reduced the susceptibility to additional ictal events during the postictal refractory period. Hence, the increased FOS protein induced by generalized tonic clonic seizures may participate in postictal mechanisms.

Transplant of cultured neuron-like differentiated chromaffin cells in a Parkinson's disease patient. A preliminary report.

BACKGROUND: Treatment of Parkinson's Disease (PD) has been attempted by others by transplanting either the patient's own adrenal medullary tissue or fetal substantia nigra into caudate or putamen areas. However, the difficulties inherent in using the patient's own adrenal gland, or the difficulty in obtaining human fetal tissue, has generated the need to find alternative methods. METHODS: We report here of an alternative to both procedures by using as transplant material cultured human adrenal chromaffin cells differentiated into neuron-like cells by extremely low frequency magnetic fields (ELF MF). RESULTS: The results of this study show that human differentiated chromaffin cells can be grafted into the caudate nucleus of a PD patient, generating substantial clinical improvement, as measured by the Unified Rating Scale for PD, which correlated with glucose metabolism and D2 DA receptor increases as seen in a PET scan, while allowing a 70% decrease in L-Dopa medication. DISCUSSION: This is the first preliminary report showing that transplants of cultured differentiated neuron-like cells can be successfully used to treat a PD patient.

Comparative study of transfer factor and acyclovir in the treatment of herpes zoster.

Reactivation of varicella herpes virus (VHV), latent in individuals who have previously suffered varicella, gives rise to herpes zoster and in some cases leads to a sequela of post herpetic neuritis with severe pain which is refractory to analgesics. Many different antiviral agents have been tried without achieving satisfactory results. Of all the antiviral agents employed, acyclovir has been the most successful in reducing post herpetic pain. However acyclovir has not been as reliable as interferon alpha (IFN-alpha). We have previously looked into the use of transfer factor (TF) as a modulator of the immune system, specifically with respect to its effectiveness in the treatment of herpes zoster. In this work findings from a comparative clinical evaluation are presented. A double blind clinical trial of TF vs acyclovir was carried out in which 28 patients, presenting acute stage herpes zoster, were randomly assigned to either treatment group. Treatment was administered for seven days and the patients were subsequently submitted to daily clinical observation for an additional 14 days. An analogue visual scale was implemented in order to record pain and thereby served as the clinical parameter for scoring results. The group treated with TF was found to have a more favorable clinical course, P < or = 0.015. Laboratory tests to assess the immune profile of the patients were performed two days prior and 14 days after initial treatment. The results of these tests showed an increase in IFN-gamma levels, augmentation in the CD4+ cell population but not the percentage of T rosettes in the TF treated group. These parameters were however insignificantly modified in patients receiving acyclovir. Although TF treated patients showed an increase in CD4+ counts these cells remained below the levels for healthy individuals. The fact that IFN-gamma levels as well as the counts for CD4+ cells rose in the TF treated group and not in the acyclovir one is very significant and confirms the immunomodulating properties of TF.

Brindley's gland exocrine products of Triatoma infestans.

Volatile exocrine products of the metathoracic Brindley's glands in Triatoma infestans (Hemiptera: Reduviidae) were obtained by dissection and by sampling the air passed over agitated live adults. Isobutyric acid was the main component in the glands, together with isobutyl, isoamyl and amyl alcohols, 2-phenylethanol and other carboxylic acids and esters. Isobutyric acid, isobutyl, isoamyl and amyl alcohols and ester were also found to be emitted into the air, apparently for defence. No volatile products were detected in the metasternal glands.

Persistence of the typical spike-wave EEG pattern after surgical excision of a temporal lobe astrocytoma and apical lobectomy.

This is a report on a patient with intractable 'primary' generalized seizures and typical spike-wave EEG patterns, in whom an unexpected temporal lobe astrocytoma was detected by MRI studies. Clinical and electrophysiological studies were performed before and after surgical excision of the tumor and apical temporal lobectomy in an attempt to determine whether 'primary' generalized seizures and EEG patterns and the temporal lobe tumor were only coincident neurological disorders or were indeed related. Before resection, the patient consistently showed a typical spike-wave EEG pattern with no background and paroxysmal activities suggestive of 'secondary' bilateral synchrony in 10 consecutive conventional EEG recordings; neither spontaneous interictal nor ictal ECoG activities suggested focal temporal lobe epileptogenesis. After resection, the patient showed increased pentylenetetrazol (PTZ) convulsive threshold, and reduction in the number of 'primary' generalized seizures, although typical spike-wave EEG discharges persisted. These observations suggest that 'primary' generalized seizures, EEG patterns and the temporal tumor were physiopathologically interrelated, and that both reticulocortical and corticoreticular mechanisms may participate together in the genesis of 'primary' generalized clinical and EEG activities.

Neurotransmitter levels in cerebrospinal fluid in relation to severity of symptoms and response to medical therapy in Parkinson's disease.

Determinations of biopterin (BP), homovanilic acid (HVA), glutamic acid (GTA), and glutamine (GT) levels in cerebrospinal fluid (CSF) obtained through a lumbar tap were performed in 20 parkinsonian patients in different stages of evolution and without medication. In patients with motor symptoms not related to Parkinson's disease (dystonia, dyskinesia and essential tremor) (n = 4). In 7 other neurological patients subjected to spinal tap for diagnostic procedures neurotransmitters were also determined and taken as control groups. In 14 of the patients with Parkinson's disease, the symptoms were evaluated using conventional scales (UPDS, NYPDS, NWPDS, Schwab and England, and Hoehn and Yahr scale). The amplitude and the frequency of tremor were quantitatively evaluated through a single plane accelerometer Grass SP-1, akinesia was measured through reaction time to auditory stimuli, and rigidity through the speed of lineal movement. Evaluations were performed with the patient not on any medication for 1 week and repeated 1 h after the intake of 250 mg of 200/50 L-dopa/carbidopa preparation (Sinemet) and on a different day after the intake of biperiden (Akineton) 6 mg/day. Differences in neurotransmitter or metabolites levels between Parkinson's disease and control groups were determined through an independent Student's t test. Correlation between severity of symptoms in the scales and for each individual symptom measured through the quantitative tests and the levels of neurotransmitters in CSF were evaluated through the Pearson correlation analysis test. Modifications in the motor performance after administration of Sinemet and Akineton, and the levels of neurotransmitters were indirectly determined. RESULTS. (1) There were significant differences between the levels of BP and GT in patients with Parkinson's disease and control groups, (2) lower GTA levels correlated with more severe rigidity and akinesia, and with the best response to the administration of L-dopa and may be an important marker for prognosis, and (3) lower levels of GT correlated with least akinesia, but not with tremor, which may indicate that the akinesia depends on other biochemical abnormalities besides dopamine depletion.