Changes in motor cortex excitability with stimulation of anterior thalamus in epilepsy

BACKGROUND

Deep brain stimulation (DBS) is an effective treatment for movement disorders and pain. Recently, bilateral DBS of the anterior nucleus of thalamus (AN) was performed for the treatment of intractable epilepsy. This surgery reduced seizure frequency in an initial group of patients. However, its physiologic effects on the cortex and mechanisms of action remain poorly understood. Different classes of antiepileptic drugs (AEDs) have distinct effects on the excitatory and inhibitory circuits in the motor cortex, which can be studied noninvasively by transcranial magnetic stimulation (TMS).

OBJECTIVE

To examine the effects of bilateral AN DBS on motor cortex excitability in epilepsy and compare these to the known effects of AEDs.

METHODS

Cortical excitability was assessed in five medicated epilepsy patients with bilateral stimulators implanted in the anterior thalamus and nine healthy controls. Single and paired TMS were used to examine cortical inhibitory and facilitatory circuits. Electromyography was recorded from the dominant hand, and TMS was applied over the contralateral motor cortex. Patients were studied during DBS turned off (OFF condition), DBS with cycling stimulation mode (1 minute on, 5 minutes off; CYCLE), and DBS with continuous stimulation (CONTINUOUS) in random order on 3 consecutive days.

RESULTS

Motor thresholds were increased in the patients regardless of DBS condition. Active short-interval intracortical inhibition (SICI) was significantly reduced in the OFF and CYCLE conditions but returned toward normal levels in the CONTINUOUS condition. Rest SICI, long interval intracortical inhibition, and silent period duration were unchanged.

CONCLUSIONS

Increased short-interval intracortical inhibition with continuous deep brain stimulation (DBS) suggests that thalamic DBS might drive cortical inhibitory circuits, similar to antiepileptic drugs that enhance gamma-aminobutyric acid inhibition.

Cost-consequence analysis in a French setting of screening and optimal treatment of nephropathy in hypertensive patients with type 2 diabetes

AIM

Forty percent of hypertensive type 2 diabetes patients develop nephropathy (microalbuminuria/overt nephropathy), indicating end organ damage, increased risk of cardiovascular disease (CVD), and death. In France, screening rates and nephropathy treatment are suboptimal. We assessed the health economic impact of nephropathy screening in hypertensive patients with type 2 diabetes followed by optimal antihypertensive/nephroprotective therapy in those who have nephropathy in France.

METHODS

A Markov/Monte Carlo model simulated lifetime impacts of screening for albuminuria (microalbuminuria/overt nephropathy) using semi-quantitative urine dipsticks in a primary care setting, and subsequent addition of irbesartan 300 mg to conventional therapy in hypertensive type 2 diabetes patients identified as having nephropathy. Progression from no renal disease to end-stage renal disease (ESRD) was simulated. Probabilities, utilities and costs of CVD events, medications and ESRD treatment came from published sources. Cumulative incidence of ESRD, life expectancy, quality-adjusted life years (QALYs) and direct costs were projected. Second-order Monte Carlo simulation accounted for uncertainty in multiple parameters. Costs and QALYs were discounted at 3% annually.

RESULTS

Screening and optimized treatment led to a 42% reduction in the cumulative incidence of ESRD from 10.1 +/- 9.9% without screening to 5.8 +/- 5.7%, improvements in life expectancy of 0.38 +/- 0.59 years, improvements of 0.29 +/- 0.32 QALYs, and decreased costs of Euro 4,812 +/- 7,882/patient over 25 years. Sensitivity analysis showed that the results were robust. Screening was most beneficial when performed in younger patients.

CONCLUSION

In hypertensive patients with type 2 diabetes, screening for albuminuria followed by optimal antihypertensive/nephroprotective treatment improves patient outcomes and leads to cost savings in France.

Streptococci dominate the diverse flora within buccal cells

Previously, we reported that intracellular Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythensis were present within buccal epithelial cells from human subjects, as lesser components of a polymicrobial flora. In this study, we further characterized that intracellular flora by using the same double-labeling techniques to identify Fusobacterium nucleatum, Prevotella intermedia, oral Campylobacter species, Eikenella corrodens, Treponema denticola, Gemella haemolysans, Granulicatella adiacens, and total streptococci within buccal epithelial cells. All those species were found within buccal cells. In every case, species recognized by green-labeled species-specific probes were accompanied by other bacteria recognized only by a red-labeled universal probe. Streptococci appeared to be a major component of the polymicrobial intracellular flora, being present at a level from one to two logs greater than the next most common species (G. adiacens). This is similar to what is observed in oral biofilms, where diverse species interact in complex communities that often are dominated by streptococci.

Optical and dosimetric properties of zircon

Irradiation effects were investigated in zircon crystals by methods of optical absorption and luminescence. Special attention was given to the effects of vacuum ultraviolet (VUV) radiation. The same main thermoluminescence (TL) peaks with the same thermal activation energies appeared after VUV as after X- or beta irradiation, indicating that the same traps were induced by the different irradiations. TL excitation spectra in the VUV showed an increase <220 nm and maxima near 190 and 140 nm. Excitation spectra of phototransferred TL (PTTL) and optically stimulated luminescence (OSL) were also measured. Most TL emission bands also appeared in the X-luminescence, PTTL and OSL. Dosimetric properties such as the TL radiation sensitivity, thermal stability of radiation-induced defects and TL dose dependence were also investigated. The radiation sensitivity of zircon was by an order of magnitude lower than that of TLD-100. The 355 K TL peak showed linear dose dependence only up to approximately 500 Gy and the 520 K peak up to approximately 1800 Gy.

Superlinear dose dependence of high temperature thermoluminescence peaks in Al2O3:C

We report on strong superlinearity of high temperature (300-700 degrees C) thermoluminescence (TL) peaks in alpha-Al2O3:C powder. The main dosimetric peak at approximately 200 degrees C, previously found to exhibit slight superlinearity, is now shown to yield a slope of approximately 1.15 on a log(intensity) vs. log(dose) curve. Higher temperature peaks at approximately 320, 450 and 650 degrees C, previously reported following UV and X-ray excitation, have now been observed after beta irradiation and showed stronger superlinearity. Using a blue filter, the weak peak at approximately 320 degrees C started about quadratically and the slope on the log-log scale decreased gradually from 2 to about unity at approximately 100 Gy. The two higher temperature peaks at approximately 450 and approximately 650 degrees C also exhibited a strong superlinear dose dependence in this dose range, with an average slope of approximately 2. Roughly similar behaviour has been found when a UV filter was used. The possible explanation of the strong superlinearity is discussed.

Non-monotonic dose dependence of thermoluminescence

The thermoluminescence (TL) intensity in different materials is usually a monotonic increasing function of the dose, which quite often reaches a saturation value. In several materials, however, non-monotonic dose dependence has been observed. The TL intensity reached a maximum at a certain dose and decreased at higher ones. Some authors refer to this effect as 'radiation damage'. In the present work, we show that the non-monotonic dependence can easily be demonstrated to result from competition between transitions model with two trapping states and two kinds of recombination centres. Two kinds of competition are considered. One in which competition during excitation dominates, the filling of the active luminescence centre is non-monotonic, and the resulting TL is non-monotonic. In the other, the filling of traps and centres is monotonically increasing, but the competition during heating causes TL intensity to reach a maximum and decline at higher doses.

Controlling the phenotype and function of mesenchymal stem cells in vitro by adhesion to silane-modified clean glass surfaces

The behaviour of human mesenchymal stem cells (hMSC) when cultured in contact with a range of silane-modified surfaces was examined to determine if changing the surface chemistry affected the early differentiation potential of mesenchymal stem cells in vitro over a 7-day period. Cells were cultured for 1 and 7 days in direct contact with glass which had been functionalized by surface treatment to provide a range of different surfaces: -CH(3), -NH(2), -SH, -OH, and -COOH modified surfaces and a clean glass reference (TAAB). Viable cell adhesion was quantified by Lactate Dehydrogenase assay, and morphology and viability was qualitatively evaluated using calcein AM, ethidium homodimer, cytoskeletal (F Actin), extra-cellular matrix (fibronectin and vitronectin) and Hoechst staining (nucleus). The expression of selected differentiation markers, Collagen II (chondrocytes), CBFA1 (bone transcription factor), Collagen I (MSC marker) and TGF-beta3 (extra-cellular matrix production) was determined using real time polymerase chain reaction. The expression of ornithine decarboxylase was evaluated as a marker of proliferation. Surfaces of the -NH(2) group demonstrated the greatest level of cell adhesion by the 7-day period, and mRNA expression profiles indicated osteogenic differentiation, increased CBFA1 and decreased Collagen II expression. Cells cultured in contact with the -COOH surfaces displayed different cell morphologies, fibronectin and vitronectin spatial distributions compared with the cells in contact with the -NH(2) surfaces, in addition to an increase in Collagen II expression, indicative of chondrogenic differentiation. The modifications to the surface chemistry of glass did affect cell behaviour, both in terms of viable cell adhesion, morphology and profiles of mRNA expression, providing the means to alter the differentiation potential of the MSCs.

The vital status of human buccal epithelial cells and the bacteria associated with them

OBJECTIVE

We have shown that buccal epithelial cells (BEC) from humans can contain a polymicrobial intracellular flora. Members of that flora can induce proinflammatory responses. However, our subjects all had healthy oral mucosa. This might reflect tolerance of bacterial invasion by live BEC. Alternatively, inflammation might not occur if invaded cells were mostly dead, and thus unable to mount a response. This study addressed that issue, by determining the vital status of BEC and the bacteria associated with them.

DESIGN

Initial experiments indicated that BEC were anomalously permeable to the DNA stain propidium iodide. We used that property to develop a protocol that combined the DNA stains SYTO 9 and propidium iodide (indicators of bacterial viability) with the esterase substrate calcein blue AM (an indicator of BEC viability), and Annexin V Alexa Fluor 647 conjugate (an apoptosis marker). That protocol was applied to BEC collected from 36 human subjects.

RESULTS

On average, 70% of BEC displayed calcein blue staining, with no binding of Annexin V, 25% showed signs of apoptosis, and 5% did not stain with calcein blue. The mean percent of BEC with live cell-associated bacteria was 29%. Collectively, 25% of total BEC displayed calcein blue staining and live (SYTO 9 stained) bacteria. Only 1% of total BEC were negative for calcein blue and associated with live bacteria.

CONCLUSIONS

Our findings suggest that live BEC are tolerant of bacterial invasion. This may be due to complex interactions between members of the polymicrobial flora and their host BEC.

Mirror movements in parkinsonism: evaluation of a new clinical sign

BACKGROUND

Mirror movements (MM) are not widely appreciated in parkinsonism and no report has evaluated this clinical sign in detail.

OBJECTIVES

To define the parkinsonian clinical features associated with MM in patients with early, asymmetric parkinsonism.

METHODS

Twenty seven patients with early Parkinson's disease were evaluated using a standardised videotaping protocol. MM were scored from blinded video assessment using a clinical scale that rates the amplitude, distribution, and proportion of mirroring in the less affected limb. Parkinsonian features were combined into axial and lateralised scores using related items of the Unified Parkinson's Disease Rating Scale.

RESULTS

MM were present in 24 of 27 patients. There was a significant linear correlation between the degree of asymmetry of motor deficits and MM on the less affected side. The effect of asymmetry was greater when the proportional rather than the absolute motor difference between sides was largest. Asymmetry in leg rigidity was the most important examination feature in the prediction of contralateral foot mirroring.

CONCLUSIONS

MM are a clinical feature of the unaffected or less affected side in mild asymmetric parkinsonism. Their presence may be a useful clinical finding in early parkinsonism.

Actively regulating bioengineered tissue and organ formation

OBJECTIVES

Describe current and future approaches to tissue engineering, specifically in the area of bone regeneration. These approaches will allow one to actively regulate the cellular populations participating in this process.

DESIGN

Many approaches to actively regulate cellular phenotype are under exploration, and these typically exploit known signal transduction pathways via presentation of specific receptor-binding ligands, and may also deliver mechanical information via the physical bridge formed by the receptor-ligand interactions. Cellular gene expression may also be directly modulated utilizing gene therapy approaches to control tissue regeneration.

CONCLUSIONS

Significant progress has been made to date in bone regeneration using inductive molecules and transplanted cells, and FDA approved therapies have resulted. While approaches to date have focused on delivery of single stimuli (e.g. one growth factor), future efforts will likely attempt to more closely mimic developmental processes by the delivery of multiple inputs to the cells in spatially and temporally regulated fashions.

Centrifugal force model for pedestrian dynamics

In this paper, a centrifugal force model is developed for pedestrian dynamics. The effects of both the headway and the relative velocity among pedestrians are taken into account, which can be expressed by a "centrifugal force" term in dynamic equation. The jamming probability due to the arching at exits for crowd flows is provided. A quantitative analysis of the crowd flowing out of a hall shows that the average leaving time T is a function of the exit width W in negative power. The related simulation indicates that the proposed model is able to reproduce the self-organization phenomena of lane formation for sparse flows.

Changes in cortical excitability with thalamic deep brain stimulation

BACKGROUND

Deep brain stimulation (DBS) is an effective treatment for several movement disorders. However, its mechanism of action is largely unknown. Both lesioning and DBS of the ventralis intermedius (VIM) nucleus of thalamus improve essential tremor. Although DBS was initially thought to inhibit the target neurons, recent studies suggest that DBS activates neurons.

OBJECTIVE

To test the hypothesis that thalamic DBS activates the target area in patients with essential tremor.

METHODS

Cortical excitability was assessed in seven unmedicated patients with essential tremor using unilateral stimulators implanted in the VIM of the dominant hemisphere and in 11 healthy controls using transcranial magnetic stimulation (TMS). Patients were studied during optimal DBS (ON condition), half the optimal frequency (HALF), and with DBS off (OFF) in random order. Tremor was assessed after a change in DBS setting. Electromyography was recorded from the dominant hand, and TMS was applied over the contralateral motor cortex using single and paired pulses to elicit motor evoked potentials (MEPs). MEP recruitment was determined using stimulus intensities from 100% to 150% of motor threshold.

RESULTS

Tremor scores were significantly improved with DBS ON. Analysis of variance showed a significant interaction between condition (ON, HALF, OFF, Normal) and stimulus intensity on MEP amplitude. During DBS ON MEP amplitudes were significantly higher compared with controls at high but not at low TMS intensities.

CONCLUSION

Because the ventralis intermedius (VIM) projects directly to the motor cortex, the high motor evoked potential amplitude with deep brain stimulation ON suggests that VIM DBS activates rather than inhibits the target area.

beta2-Adrenergic receptor gene variations associated with stage-2 hypertension in northern Han Chinese

The aim of this study was to investigate the association between polymorphisms in the beta(2)-adrenergic receptor gene (ADRB2) (-47C/T, Arg16/Gly, Gln27/Glu) and stage-2 hypertension in northern Han Chinese. We recruited 503 individuals with stage-2 hypertension and 504 age-, gender-, and area-matched controls from the International Collaborative Study of Cardiovascular Disease in Asia. Genotyping was performed using PCR-RFLP. Logistic regression analyses revealed that carriers of the Gly16 allele had a significantly higher odds ratio (OR) for hypertension, while carriers of the Glu27 allele had a significantly lower OR. In multivariate linear regression analyses, the Arg16/Gly and Gln27/Glu genotypes were significantly associated with systolic blood pressure level (p = 0.004 and p < 0.001, respectively). In haplotype analyses, we found the frequency of haplotypes composed of the Gly16 and Gln27 alleles was significantly higher, whereas the frequency of haplotypes composed of the Arg16 and Glu27 alleles was significantly lower, in hypertensives compared to their controls (both p = 0.001). These results indicate that the Gly16 and Gln27 alleles of the ADRB2 gene confer an increased risk for stage-2 hypertension in this northern Han Chinese population.

X-Ray Storage Luminescence of BaFCl:Eu2+ Single Crystals

Temperature behaviors of X-ray luminescence (XL), photoluminescence (PL), photostimulated luminescence, and thermoluminescence (TL) were studied in BaFCl:Eu2+ single crystals from room temperature to liquid nitrogen temperature. Six emissions at 275, 315, 365, 385, 435, and 500 nm were observed in the XL spectra and are attributed to Cl excitons, V(k)(Cl2-), the 4f65d1 (2e(g)) --> 4f7 (8S(7/2)) transition of Eu2+, and oxygen vacancies, respectively. Three emission peaks at 315, 365, and 390 nm were observed in the PL and TL measurements. These three emissions are from the transitions of 4f7(6I(7/2)) --> 4f7(8S(7/2)), 4f7(6P(7/2)) --> 4f7(8S(7/2)), and 4f65d1 (2e(g)) --> 4f7(8S(7/2)) of Eu2+, respectively. In our measurements, we observed that the emission of Eu2+ increases in intensity upon beta-irradiation and did not see any signals related to Eu3+ ions, which indicates that Eu2+ ions might not be oxidized to Eu3+ upon X-ray or beta-irradiation. Instead, the color centers, Cl excitons, and oxygen defects are created and are stable at room temperature, and they might play a key role in the storage luminescence.

The effects of drinks made from simple sugars on blood pressure in healthy older people

The objective of the research was to determine the blood pressure (BP) lowering effects in older people of 50 g carbohydrate drinks with varying carbohydrate content using a randomised, cross-over study with ten (six females) healthy older subjects (mean age 72.20 (sem 1.50) years). BP, heart rate and glucometer-derived blood glucose levels were determined at baseline and following the ingestion of equal volumes (300 ml) of water and carbohydrate drinks with varying nutrient content (glucose, sucrose and fructose). A significant decline in BP over the first 60 min was seen following glucose (systolic BP (SBP) P<0.01, diastolic BP (DBP) P<0.01, mean arterial BP (MAP) P=0.03) and sucrose (SBP P<0.01, DBP P<0.01, MAP P<0.01) ingestion, although the decrease occurred earlier after glucose than sucrose ingestion (SBP 7.33 (sem 2.19) v. 21.00 (sem 4.30) min (P=0.03) and MAP 11.22 (sem 3.10) v. 17.00 (sem 3.78) min (P=0.03)). BP increased after water ingestion (SBP P=0.04, DBP P=0.18, MAP P=0.02) but did not change after fructose ingestion (SBP P=0.36, DBP P=0.81, MAP P=0.34). Post hoc analyses revealed that the BP (SBP, DBP and MAP) decrease following glucose and sucrose ingestion were similar but significantly greater than following fructose or water ingestion. Sucrose, which is used widely (table sugar), reduces BP as much as glucose. In contrast to this, fructose ingestion causes no change in BP. Further studies are required to determine if the substitution of glucose or sucrose with fructose may be beneficial in the medical management of older people with severe symptomatic postprandial hypotension.