K. Sotirakoglou

Silent period to transcranial magnetic stimulation: construction and properties of stimulus-response curves in healthy volunteers

Silent period (SP) is widely used in transcranial magnetic stimulation studies. Methodologically, SP is usually elicited at stimulus intensities corresponding to a certain percentage of corticomotor threshold. Because this approach might lead to factitious SP changes, the present study was designed to develop, in a stepwise manner, a method for investigating SP independently of corticomotor threshold. First, stimulus–response (S–R) curves of SP against stimulus intensity (SI) were constructed and quantitatively described in healthy volunteers. Second, various methodological issues such as the optimum model for describing the relationship between SP duration and SI and the importance of the type of stimulating coil were addressed. Finally, the proposed method and a commonly used method (eliciting SPs at 130% MT SI) were directly compared for a group of epileptic patients for whom administration of oxcarbazepine resulted in significant corticomotor threshold elevation. Twenty-one subjects (eleven females, median age, 38 years) were studied. SPs were obtained with a figure-of-eight coil using a standardized procedure (recording, FDI). Pilot experiments indicated that at least four trials were required, at each intensity level, to estimate the mean SP duration within 10% of the true mean. Therefore, SPs were determined from the average of four trials with 5% increments from 5 to 100% maximum SI. In a second set of experiments, SPs were obtained for fifteen subjects using a circular coil. In a third set of experiments, eight epileptic patients were studied before and after administration of oxcarbazepine (mean dose 1553 mg, range 900–1800 mg). The S–R curves were fitted to a Boltzman function and to first-order to fourth-order polynomial and sigmoid functions. The Boltzman function described the data accurately (R2=0.947–0.990). In addition, direct comparison of the six models with an F-test proved the superiority of the first. The best-fit parameters of the reference curve, i.e. the maximum and minimum values, the slope, and V50 (the SI at which SP duration is halfway between Min and Max) were 230.8±3.31 ms (x±SEM), −11.51±3.31 ms, 11.56±0.65%, and 49.82±0.65%, respectively. When the curves obtained with the circular coil were compared with those obtained with the figure-of-eight coil, there were differences between V50 (51.69±0.72 vs 47.95±0.82, P<0.001) and SP threshold (31.15 vs 24.77, P<0.01) whereas the other best-fit values did not differ significantly. Oxcarbazepine increased corticomotor threshold from 45.3±5.8% at baseline to 59.4±10.4% (P<0.001). According to the commonly used method, the drug significantly prolonged SP (from 117.6±42.4 ms to 143.5±46.5 ms, P<0.001) and, consequently, enhanced brain inhibition. In contrast, study of the SP curves led to the conclusion that oxcarbazepine does not affect the Max value and slope but significantly increases V50 and SP threshold (from 54.5±4.9% to 59.9±7.2% and from 29.1±6.4% to 34.6±6.8%, respectively, P<0.01). These findings imply that oxcarbazepine does not enhance brain inhibitory mechanisms. Thus, in situations characterized by significant changes in corticomotor threshold the proposed method provides results clearly different from a commonly used approach. It is concluded that S–R curves obtained with a figure-of-eight coil in 5% increments and fitted to a Boltzman function provide an accurate, comprehensive, and clinically applicable method for exploring SP.

Long-term results of stem cell transplantation for MS A single-center experience

Objective: To report long-term results of a phase I/II study conducted in a single center in order to investigate the effect of hemopoietic stem cell transplantation (HSCT) in the treatment of multiple sclerosis (MS). Methods: Clinical and MRI outcomes of 35 patients with aggressive MS treated with HSCT are reported after a median follow-up period of 11 (range 2–15) years. Results: Disease progression-free survival (PFS) at 15 years is 44% for patients with active CNS disease and 10% for those without (p = 0.01); median time to progression was 11 (95% confidence interval 0–22) and 2 (0–6) years. Improvements by 0.5–5.5 (median 1) Expanded Disability Status Scale (EDSS) points were observed in 16 cases lasting for a median of 2 years. In 9 of these patients, EDSS scores did not progress above baseline scores. Two patients died, at 2 months and 2.5 years, from transplant-related complications. Gadolinium-enhancing lesions were significantly reduced after mobilization but were maximally and persistently diminished post-HSCT. Conclusion: HSCT is not a therapy for the general population of patients with MS but should be reserved for aggressive cases, still in the inflammatory phase of the disease, and for the malignant form, in which it can be life-saving. HSCT has an impressive and sustained effect in suppressing disease activity on MRI. Classification of evidence: This study provides Class IV evidence that HSCT results in PFS rates of 25%. PFS rate was significantly better in patients with active MRI lesions; HSCT also resulted in a significant reduction in the number and volume of gadolinium-enhancing lesions on MRI.

On base and Turyn sequences

Base sequences of lengths n + 1, n + 1, n , n are constructed for all decompositions of 4/1 + 2 into four squares for n = 19,... , 24. The construction is achieved through an algorithm which is also presented. It is proved through an exhaustive search that Turyn sequences do not exist for n = 18, ... , 27 ; since Turyn sequences cannot exist for n = 28 or 29, the first unsettled case is n = 30.

On Golay sequences

Abstract Golay sequences are two binary (+1, -1) sequences with nonperiodic autocorrelation function zero. These sequences have a wide range of applications in constructing orthogonal designs and Hadamard matrices, in coding theory, in multislit spectrometry and in surface acoustic wave devices. In this paper we develop an algorithm for constructing such sequences. We prove that Golay sequences of length n = 2 · 7 2 t do not exist and we give new proofs of some known results. In particular we show there are no Golay sequences of length 98. We conjecture that there are no Golay sequences of length 2 · q 2 t where q is not the sum of two integer squares.

TOPIRAMATE PROMOTES NEUROLOGICAL RECOVERY IN A NEW MODEL OF TRAUMATIC BRAIN INJURY IN RATS

The aim of this study is to investigate the neuroprotective effects of the anticonvulsant topiramate in a new model of traumatic brain injury in rats. A new model of traumatic brain injury, based on the weight-drop technique, was developed for the purpose of this study. Seventy-five male Wistar rats weighing 320-470 g were studied. All rats were anesthetized, subsequently submitted to a round craniectomy in the left parietal region and a weight of 50 g was used for the production of a cortical contusion. In study I, 44 rats were randomized in three groups to receive either topiramate 40 mg/kg (n=13), topiramate 60 mg/kg (n=14), or water for injection (n=17) i.p. 30 min after the injury and every 12 h thereafter for 3 days. The rats were tested clinically 24 h, 72 h, 10 days and 20 days after the injury. On day 21 the animals were sacrificed and the brains were removed and prepared for histopathological analysis. In study II, 19 rats were randomized to receive either topiramate 60 mg/kg (n=10) or water for injection (n=9) i.p. 30 min after the injury and every 12 h (four doses in total). 48 h after the injury the animals were sacrificed and the brains were rapidly removed and analyzed for water content with the dry-wet weight technique. The animals that received topiramate performed significantly better in neurological tests compared to the animals that received vehicle ten (P<0.05) and 20 (P<0.001) days after the injury. There was no difference between the high and the low dose of the drug. Topiramate had no effect on the anatomic volume of the lesion. The animals that received topiramate had a tendency to present with less cerebral edema formation, but the difference was not statistically significant (P>0.05). These findings suggest that topiramate promotes neurological recovery in rats after traumatic brain injury without affecting the final size of the traumatic lesion and that it might play a role in the reduction of post-traumatic cerebral edema.

ESTIMATION OF THE SPREAD OF PATHOGENIC MYCOBACTERIA IN ORGANIC BROILER FARMS BY THE POLYMERASE CHAIN REACTION

Organic poultry breeding allows for increased exposure of birds to soil, faeces, and wildlife, which have been associated with the transmission of mycobacterial infections. Therefore the aim of this study was to investigate the spread of the major pathogenic mycobacteria in organically reared broilers in Greece using a diagnostic algorithm that relied on a combination of the polymerase chain reaction (PCR) and the restriction fragment length polymorphism analysis (RFLP). Liver, spleen and gonads from 81 to 150 days old broilers were aseptically collected post-mortem. 500 broilers from a population of 35,370, reared in the 25 registered as organic farms in Greece for the 2005 were used. DNA was isolated and incorporated to PCR targeted to 16S-rRNA gene (for Mycobacterium spp.), IS6110 (for Mycobacterium tuberculosis complex-MTBc), IS1245 (for Mycobacterium avium complex-MAC), IS901 (for M. avium subsp. avium-MAA) and hsp65 (for Mycobacterium genavense, by PCR-RFLP). The mean prevalence of mycobacteria detected by PCR with a 95% confidence interval was estimated to 4.4-8.8%. The relevant percentage with regard to the mycobacterial species that were included in this study was 0.17-2.03% for MAC, 2.11-3.39% for MTBc and 0.66-3.08% for mycobacteria not belonging to any of the above groups. None of the mycobacteria detected were identified as MAA or M. genavense. Considering that avian tuberculosis has been eradicated from conventional farms, the level and the pattern of positivity recorded here, indicates that our results may be associated with the specific conditions that apply to organic breeding.

StimulatingOrobanche ramosa seed germination with anAscophyllum nodosum extract

Algit Super®, an extract ofAscophyllum nodosum, was found to be an effective stimulant for the germination ofOrobanche ramosa seeds. The biological activity of Algit Super® was tested at a wide range of concentrations from 2.5 v/v to 1.2 × 10−3 v/v. The seed germination in all studiedO. ramosa populations showed a concentration dependence, with an inhibitory effect at higher concentrations. The response ofO. ramosa to Algit Super® resembled its response to the reference stimulant GR24. VariousO. ramosa populations demonstrated differential response to the stimulant.

The effect of long term under- and over-feeding on the expression of genes related to glucose metabolism in mammary tissue of sheep

Glucose utilisation for lactose synthesis in the mammary gland involves expression of a large number of genes whose nutritional regulation remains poorly defined. In this study, the effect of long term under- and over-feeding on the expression of genes [glucose transporter 1: GLUT1, glucose transporter 3: GLUT3, Sodium glucose contransporter 1: SGLT1, two isoforms of β- (1,4) galactosyltransferase: β- (1,4) GAT1, β- (1,4) GAT3 and α-lactalbumin: LALBA] related to glucose metabolism in sheep mammary tissue (MT) was examined. Twenty-four lactating dairy sheep were divided into three homogenous sub-groups and fed the same ration in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant reduction on mRNA of GLUT1 and LALBA gene in the MT of underfed sheep, compared with the respective controls and overfed and a significant reduction on mRNA level of SGLT1 and β- (1,4) GAT1 in the MT of underfed sheep, compared with the overfed ones. A significant increase in the GLUT3 mRNA accumulation in the MT of both under- and over- fed sheep was found. Additionally, a trend of reduction on β- (1,4) GAT3 mRNA level in the MT of the underfed sheep, compared with the overfed, was observed. A close positive relationship was obtained between the mRNA transcripts accumulation of GLUT1, SGLT1, β- (1,4) GAT1 and LALBA gene with the milk lactose content and milk lactose yield respectively. In conclusion, feeding level and consequently nutrient availability, may affect glucose uptake and utilisation in sheep MT by altering the GLUT1, GLUT3, SGLT1, β- (1,4) GAT1 and LALBA gene expression involved in their metabolic pathways.

Changes in essential oil content and composition of Origanum vulgare spp. hirtum during storage as a whole plant or after grinding and mixing with a concentrate ruminant diet

Essential oils (EO) from aromatic plants (AP) are used in ruminants’ diets due to several biological activities. The inclusion of AP in ruminants’ diets can be done as dried material, as they are harvested once a year. However, storage is one of the main factors that affect the EO content and chemical composition. Thus, the objective of this study was to determine the effect of storage, in the shade under ambient conditions, on the EO content and chemical composition (a) of Origanum vulgare spp. hirtum as a whole plant (OP) and/or (b) as the powdered form after mixing with the concentrate diet. The results showed that storage of the whole OP in the shade for six months has a very low EO loss (5.8%), while grinding and mixing OP with concentrates causes different losses, which depend on the OP/concentrate ratio and the storage period.

The role of bentonite binders in single or concomitant mycotoxin contamination of chicken diets

Abstract Concomitant presence of mycotoxins is more likely to appear than a single mycotoxicosis since many mycotoxigenic fungi grow and produce their toxic metabolites under similar conditions. The present study was designed to evaluate the efficacy of 4 mycotoxin binders to protect meat-type chickens against single and concomitant administration in the feed of two mycotoxins, namely aflatoxin B1 (AFB1) and ochratoxin A (OTA) both at concentration of 0.1 mg/kg. A total of 440 as hatched, d-old, Ross 308 broilers were reared for 42 d. There were 11 dietary treatments. Chickens were fed on either an uncontaminated basal diet, basal diet and AFB1, basal with concomitant presence of AFB1 and OTA, basal diet and three binders A, B and C (1%) with or without AFB1 or basal diet and binder D (0.5%) with or without concomitant presence of AFB1 and OTA. Performance, carcass yield and several biochemical parameters were examined. Mycotoxin concentration in liver and breast muscle samples was determined. Broiler performance under concomitant mycotoxin contamination was poorer than that under single mycotoxicosis. Mycotoxin presence increased relative heart weight compared to that of broilers fed on uncontaminated diets. Only OTA and not AFB1 was detected and only in the liver. OTA concentration was four-fold lower in broilers fed on a diet with binder compared to those fed on contaminated diets without binder. In conclusion, the study revealed that binder composition and presence or not of multiple toxins may be important factors for optimum broiler performance under mycotoxicosis.