Increase in 20–50Hz (gamma frequencies) power spectrum and synchronization after chronic vagal nerve stimulation

OBJECTIVE

Though vagus nerve stimulation (VNS) is an important option in pharmaco-resistant epilepsy, its mechanism of action remains unclear. The observation that VNS desynchronised the EEG activity in animals suggested that this mechanism could be involved in VNS antiepileptic effects in humans. Indeed VNS decreases spiking bursts, whereas its effects on the EEG background remain uncertain. The objective of the present study is to investigate how VNS affects local and inter regional syncronization in different frequencies in pharmaco-resistant partial epilepsy.

METHODS

Digital recordings acquired in 11 epileptic subjects 1 year and 1 week before VNS surgery were compared with that obtained 1 month and 1 year after VNS activation. Power spectrum and synchronization were then analyzed and compared with an epileptic group of 10 patients treated with AEDs only.

RESULTS

VNS decreases the synchronization of theta frequencies (P < 0.01), whereas it increases gamma power spectrum and synchronization (< 0.001 and 0.01, respectively).

CONCLUSIONS

The reduction of theta frequencies and the increase in power spectrum and synchronization of gamma bands can be related to VNS anticonvulsant mechanism. In addition, gamma modulation could also play a seizure-independent role in improving attentional performances.

SIGNIFICANCE

These results suggest that some antiepileptic mechanisms affected by VNS can be modulated by or be the reflection of EEG changes.

Evidence of a role of endogenous estrogen in the modulation of autonomic nervous system

We studied heart rate variability in 14 healthy women before and after oophorectomy compared with 14 matched women who underwent hysterectomy with ovarian conservation. Surgical menopause induced a decline in cardiac vagal modulation with a shift toward sympathetic hyperactivity. Recovery of the baseline condition after 3 months of estrogen replacement therapy in oophorectomized women suggests a role of estrogen in the autonomic nervous control of the cardiovascular system.

Biological characterization of recombinant human follicle stimulating hormone isoforms

It has been established that follicle stimulating hormone (FSH) circulates in the bloodstream as a heterogeneous population of molecules. Individual FSH isoforms, while displaying identical amino acid sequences, differ in their extent of post-translational modification. As a result of these variations, the FSH isoforms exhibit differences in overall charge, degree of sialic acid or sulphate incorporation, receptor binding affinity and plasma half-life. Taking advantage of the fact that these forms can be separated from each other on the basis of their charge, we have evaluated in rats the metabolic clearance rates of the acidic [with an isoelectric point (pI) </=ISOdia</= 4.8] and the less acidic (pI > 4.8) isoforms of recombinant human FSH (rhFSH) obtained after chromatofocusing. The less acidic isoform group was found to have a faster clearance from the circulation in rats as compared with the acidic isoform group. This finding is in agreement with the lower bioactivity in vivo (as determined by the Steelman-Pohley assay) of the less acidic isoform group, compared with the acidic one. The mass spectra of the two groups of isoforms showed a difference in the sialic acid content thus highlighting the importance of these residues on the in-vivo activity of FSH. Conversely, when the two groups of isoforms were tested in vitro by using the Y1 human FSH receptor (Y1 hFSHR) assay and a reporter gene assay, no significant differences in the biological activities between these preparations were detected when test concentrations were based on mass.

A highly precise reporter gene bioassay for type I interferon

We describe the setting up and validation of a reporter gene assay for type I IFN based on monkey Vero cells transfected with pMx-Luc, a plasmid carrying the luciferase gene under the control of the type I IFN inducible mouse Mx1 promoter. Vero cells were stably transfected with pMx-Luc and clone 3-143/5 was selected on the basis of luciferase inducibility by IFN-beta. A linear dose-response relationship was found between 1 and 16 IU/ml IFN-beta. The assay was shown to be specific for IFN-alpha and -beta as no effect by a number of other cytokines including IFN-gamma could be detected. In order to render the IFN-beta reporter gene assay protocol more suitable for routine assays, a 3 x 3 balanced parallel line assay design was applied using a 96-well luminometer for luminescence measurement. The assay was shown to be precise with a coefficient of variation of less than 9%. This assay is characterized by high precision coupled to high efficiency, as reflected by a very short assay duration (1 day), when compared to the classical cytopathic effect assays for IFNs and the previously published IFN reporter gene assay based on growth hormone measurement (Lleonart, R., Näf, D., Browning, H. and Weissmann, C. (1990) A novel, quantitative bioassay for type 1 interferon using a recombinant indicator cell line. Biotechnology 8, 1263-1267).

Laparoscopic versus abdominal myomectomy: a prospective, randomized trial to evaluate benefits in early outcome

OBJECTIVE

Our purpose was to investigate the advantages of laparoscopic myomectomy versus laparotomy.

STUDY DESIGN

A prospective, randomized trial was performed on 40 women, 22 to 44 years old, undergoing myomectomy. Patients were randomized to have laparoscopy (n=20) or laparotomy (n=20). The intensity of pain was assessed by a visual analog scale at 0, 1, 2, and 3 days postoperatively. The proportions of patients who were analgesic free on day 2, discharged from the hospital by day 3, and feeling fully recuperated on day 15 were also compared.

RESULTS

The intensity of postoperative pain was lower (p<0.05) after laparoscopy than after laparotomy. A higher (p<0.05) proportion of patients was analgesic free on day 2, discharged from hospital by day 3, and feeling fully recuperated on day 15 after laparoscopy compared with laparotomy.

CONCLUSION

Laparoscopic myomectomy may offer the benefits of lower postoperative pain and shorter recovery time in comparison with laparotomy.

Evidence that carbon monoxide is a mediator of critical illness

We have measured arterial carboxyhemoglobin levels as an indicator of endogenous carbon monoxide production in 32 consecutive admissions to our Surgical Intensive Care Unit. A severity of illness score (APACHE II) was determined for each patient at the same time that blood was drawn. An increase in the APACHE II score indicates a worsening of the patient's condition. There was a positive correlation between arterial carboxyhemoglobin levels and the APACHE II score (p < 0.005). An increase in the white blood cell count indicates an increase in the severity of illness. Carboxyhemoglobin levels correlated with an increase in the white blood cell count to greater than the normal maximum count of 10.5 x 10(3) cells/mm3 within a 24 hour period (p < 0.05). These findings support our hypothesis that endogenously produced carbon monoxide may play a role in the pathogenesis of critical illness.