An acute method for multielectrode recording from the interior of sulci and other deep brain areas

Most current techniques for multielectrode recording involve chronically implanting planar or staggered arrays of electrodes. Such chronic implants are suited for studying a stable population of neurons over long periods of time but exploratory studies of the physiological properties of cortical subdivisions require the ability to sample multiple neural populations. This makes it necessary to penetrate frequently with small multielectrode assemblies. Some commercial systems allow daily penetrations with multiple electrodes, but they tend to be bulky, complex and expensive, and some make no provision for piercing the barrier of fibrous tissue that often covers the brain surface. We describe an apparatus for inserting bundles of 3-16 electrodes on a daily basis, thus allowing different neural populations to be sampled. The system is designed to allow penetration through a thick dura mater into deep brain structures. We discuss a simple method for performing multielectrode recording from cortical areas buried inside sulci using acute implantations of a bundle of electrodes. Our results show that it is possible to obtain stable recordings for at least 4h and that repeated implantations yield an average of two neurons per electrode with every electrode in the bundle picking up at least one single neuron in 70% of the implantations.     

Epidemiology of aplastic anaemia in the state of Sabah, Malaysia

Aplastic anaemia is a rare disease which is more prevalent in the Far East. In Malaysia, it appears to be unusually common in the state of Sabah. A retrospective analysis of all cases of aplastic anaemia diagnosed between January 1993 and March 1996 was undertaken. The criteria of the International Aplastic Anaemia and Agranulocytosis Study (IAAAS) was used. In this 39 month period, 31 cases were confirmed by marrow trephine biopsy to be aplastic anaemia. The male-to-female ratio was 3.4. Median age of diagnosis was 23 years. There were 24 patients (77%) who were from the Kadazan-Dusun ethnic group, which forms 18% of the population of Sabah. The incidence of aplastic anaemia in Sabah appears to be higher than that reported elsewhere in the Far East, at 4.8 per million population per year. Peak incidence is in the elderly group at 8.6 per million followed by a second peak in young people aged 15 to 24 (7.9 per million). The aplastic anaemia to total acute leukaemia ratio is 0.37. The marked male preponderance and apparent susceptibility of the Kadazan-Dusun people are also notable. A further prospective study to address the true incidence of aplastic anaemia and possible aetiologic factors accounting for these observations is necessary.     

A study of the effect of cyproheptadine on gait in hemiplegic children

The properties of cyproheptadine as an anti-spastic agent have been reported since 1980. In this study we sought to investigate whether gait function, as specified by stride length, cadence, heart rate, and also by questionnaire, correlated with cyproheptadine medication during a double-blind matched-placebo cross-over trial, undertaken on a group of 16 hemiplegic spastic patients aged 4–18 years. We found that neither qualitative nor quantitative analyses suggested any systematic change in gait parameters dependent on cyproheptadine medication. We conclude that our study on 16 patients showed no statistical evidence of improvement in spasticity due to the action of cyproheptadine. An effect was, however, found in the case of mean patient heart rate, which was 10% higher (P<0.003) at the end of the cyproheptadine medication period.     

A gradient feature weighted Minimax algorithm for registration of multiple portal images to 3DCT volumes in prostate radiotherapy

PURPOSE: To develop an accurate, fast, and robust algorithm for registering portal and computed tomographic (CT) images for radiotherapy using a combination of sparse and dense field data that complement each other. METHODS AND MATERIALS: Gradient Feature Weighted Minimax (GFW Minimax) method was developed to register multiple portal images to three-dimensional CT images. Its performance was compared with that of three others: Minimax, Mutual Information, and Gilhuijs' method. Phantom and prostate cancer patient images were used. Effects of registration errors on tumor control probability (TCP) and normal tissue complication probability (NTCP) were investigated as a relative measure. RESULTS: Registration of four portals to CTs resulted in 30% lower error when compared with registration with two portals. Computation time increased by nearly 50%. GFW Minimax performed the best, followed by Gilhuijs' method, the Minimax method, and Mutual Information. CONCLUSIONS: Using four portals instead of two lowered the registration error. Reduced fields of view images with full feature sets gave similar results in shorter times as full fields of view images. In clinical situations where soft tissue targets are of importance, GFW Minimax algorithm was significantly more accurate and robust. With registration errors lower than 1 mm, margins may be scaled down to 4 mm without adversely affecting TCP and NTCP.     

Ultra-wide-field fluorescein angiography of the ocular fundus

PURPOSE: To evaluate the clinical applicability of a novel scanning laser ophthalmoscopy imaging system for ultra-wide-field fluorescein angiography. DESIGN: Observational case report. METHODS: Wide-field fluorescein angiography images were captured in normal volunteers and in patients with a variety of clinical disorders with a newly developed scanning laser ophthalmoscope (Optomap; Optos PLC., Dunfermline, Scotland, United Kingdom) that produces high-resolution images of the fundus up to a 200-degree field. Fluorescein angiograms were performed using standard sequence times. RESULTS: Peripheral vascular perfusion of all four quadrants of a normal fundus was observed with good detail of the capillary architecture. Patients with diabetes and ocular inflammatory eye disease showed evidence of peripheral retinal nonperfusion. The relative degrees of retinal perfusion and nonperfusion could be compared in single images. CONCLUSIONS: Ultra-wide-field fundus fluorescein angiography offers the possibility of evaluating and quantitating peripheral retinal perfusion and vascular pathology in fundus disease.     

Reactivation of peroxisome proliferator-activated receptor alpha in spontaneously hypertensive rat: age-associated paradoxical effect on the heart

Prevention of left ventricular hypertrophy remains a challenge in the prevention of hypertension-induced adverse cardiac remodeling. Cardiac hypertrophy is associated with a shift in energy metabolism from predominantly fatty acid to glucose with a corresponding reduction in the expression of fatty acid oxidation enzyme genes. Although initially adaptive, the metabolic switch seems to be detrimental in the long run. This study was taken up with the objective of examining whether the stimulation of fatty acid oxidation by the activation of peroxisome proliferator-activated receptor alpha (PPARα), a key regulator of fatty acid metabolism, can prevent cardiac hypertrophy. Fenofibrate was used as the PPARα agonist. Spontaneously hypertensive rats (SHRs) in the initial stages of hypertrophy (2 months) and those with established hypertrophy (6 months) were treated with fenofibrate (100 mg·kg·d for 60 days). Cluster of differentiation 36 (CD36)-responsible for myocardial fatty acid uptake, carnitine palmitoyl transferase 1β-a mitochondrial transporter protein and medium chain acyl-Co-A dehydrogenase-a key enzyme in beta oxidation of fatty acids were selected as indicators of fatty acid metabolism. Hypertrophy was apparent at 2 months and metabolic shift at 4 months of age in SHRs. The treatment prevented cardiac remodeling in young animals but aggravated hypertrophy in older animals. Hypertrophy showed a positive association with malondialdehyde levels and cardiac NF-κB gene expression, signifying the role of oxidative stress in the mediation of hypertrophy. Expression of carnitine palmitoyl transferase 1β and medium chain acyl-Co-A dehydrogenase was upregulated on treatment. However, CD36 showed an age-dependent variation on treatment, with no change in expression in young rats and downregulation in older animals. It is inferred that the stimulation of PPARα before the initiation of metabolic remodeling may prevent cardiac hypertrophy, but reactivation after the metabolic adaptation aggravates hypertrophy. Whether the downregulation of CD36 is mediated by decreased substrate availability remains to be explored. Age-dependent paradoxical effect on the heart in response to fenofibrate, used as a lipid-lowering drug, can have therapeutic implications.     

Supplementing iron bioavailability enhanced mung bean

Iron deficiency anaemia is a major public health problem. The high incidence is either due to insufficient intake of iron or poor bio availability. Enhancing the bio availability is as important as increasing the intake. The absorption could be enhanced by including ascorbic acid and beta carotene containing fruits and vegetables into recipes of iron containing food preparations. The effect of supplementation of iron bio-availability enhanced mung bean preparations was studied on 75 women who were compared against 75 who served as controls and another 75 who consumed regular traditional recipes. The methodology included identification of suitable mung bean variety, assessing iron in vitro bio availability, mapping the anaemic women, estimating their iron levels, supplementation for one year and studying the effect of supplementation. Mung bean supplementation had increased serum protein levels from 5.36 to 6.73 g/dl, serum iron levels had increased from 16.6 to 46.7 microg/dl. The TIBC levels decreased from 555 to 508 microg/dl while serum ferritin levels increased from 3.56 to 5.94 microg/dl and Hb levels from 7.54 to 8.29 g/dl. Thus, improving the bioavailability of iron of food preparations, will improve the iron status of women.