The EMG Activity of Masticatory Muscles During Different Chewing Tasks

Mastication is a highly coordinated neuromuscular function that involves fast effective movements of the jaw and continuous modulation of muscle force. To understand the relationship between muscles during mastication it is necessary to know the position and direction of movement of the mandible. MATERIAL AND METHODS: Twenty-four young healthy adults, age ranged 17 to 27, participated in this study. They were chosen among dental students of School of Dental Medicine University in Zagreb and had to be free of sign and symptoms of TMD. Surface EMG recordings were obtained from left and right anterior temporal muscle, left and right masseter muscle and from left and right digastric muscle on the 8 channel PC based EMGA-1, apparatus for simultaneous recording of myoelectrical activity (6 differential EMG channels, input impedance 100 MW, CMRR> 95 dB at 50 Hz, bandwidth 2 Hz-1 kHz, programmable input sensitivity from 100mVpp to 20 mVpp, an 8 bit resolution A/D conversion, 2 kHz sampling rate) - occlusal sound (2 audio channels), specially designed and developed for the purpose of kinesyological examinations of stomatognathic system’s function. The disc electrodes (Ag/AgCl, diameter 10 mm) were placed 2 cm apart in the main direction of the muscle fibres. RESULTS: 1. Main effect of factor "functional movement" was significant at p<0.01, and values were the highest for gum chewing, and the lowest for empty chewing except fordigastric muscle which had lowest values at continuous isometric contraction. 2. Main effect of factor “muscles” was significant at p<0.01 for all muscles involved, values were similar for the same muscles on left and right side. 3. Main effect of factor “time” was statistically significant p<0.05 for all cases showing decreasing trends except in last minute during functional movements. 4. Interactions between factors “functional movement” and “time” were present at significance p<0.01

Efficacy of secondary isoniazid preventive therapy among HIVinfected Southern Africans: time to change policy?

Objective. To determine the efficacy of secondary preventive therapy against tuberculosis (TB) among goldminers working in South Africa. Design. An observational study. Methods. The incidence of recurrent TB was compared between two cohorts of HIV-infected miners: one cohort had received secondary preventive therapy with isoniazid and the other had not. Setting. Health service providing comprehensive care for goldminers. Participants. 338 men received secondary preventive therapy and 221 did not. Main outcome measure. Incidence of recurrent TB. Results. The overall incidence of recurrent TB was reduced by 55% among men who received isoniazid preventive therapy (IPT) compared to those who did not (incidence rates 8.6 and 19.1 per 100 person-years respectively, incidence rate ratio 0.45; 95% CI 0.26 – 0.78). The efficacy of isoniazid preventive therapy was unchanged after controlling for CD4 count and age. The number of person-years of isoniazid preventive therapy required to prevent one case of recurrent TB among individuals with a CD4 count < 200/µl and &#8805;&#61472;200/µl was 5 and 19, respectively. Conclusion. Secondary preventive therapy reduces TB recurrence: the absolute impact appears to be greatest among individuals with low CD4 counts. International TB preventive therapy guidelines for HIV-infected individuals need to be expanded to include recommendations for secondary preventive therapy in settings where TB prevalence is high. Southern African Journal of HIV Medicine Vol. 5(3) 2004: 8-1

Risk factors for incident age-related macular degeneration: pooled findings from 3 continents

Objective: To examine risk factors for incident age-related macular degeneration (AMD) after combining data from 3 population-based cohort studies. Design: Population-based cohort study. Population: A population of 9523 adults (age range, 43–95 years at baseline) living in Australia, The Netherlands, and the United States who participated in a baseline examination and a follow-up examination on average 5 or 6 years later. Methods: Similar procedures were used at all study sites. Examinations included a standardized questionnaire, pupillary dilation, and stereoscopic color fundus photography. Fundus photographs were graded for lesions associated with AMD using the Wisconsin and International Age-Related Maculopathy Grading Systems. Senior investigators from each site adjudicated all photos graded as late AMD. Main outcomes measure: Incidence of late AMD. Results: Among studies, distributions for most risk factors differed, and overall incidence rates were similar. In the Beaver Dam Eye Study, total serum cholesterol was inversely associated with incident neovascular AMD. In the Blue Mountains Eye Study, current smoking (defined as smoking at the time of the baseline examination) was associated with an increased risk of incident geographic atrophy and late AMD; increased total serum cholesterol, having diabetes, and older age at menopause were positively associated with incident geographic atrophy; and an increase in high-density lipoprotein serum cholesterol was inversely related to incident geographic atrophy. In the Rotterdam Study, current smoking was associated with an increased risk of incident geographic atrophy, neovascular AMD, and late AMD; past smoking was associated with an increased risk of incident neovascular AMD and late AMD; and an increased number of years between menarche and menopause was directly related to incident geographic atrophy. After pooling data, the only statistically significant relationships found were between smoking and total serum cholesterol and incident AMD. Current smoking was associated with an increased incidence of geographic atrophy and late AMD (odds ratios [ORs] relative to nonsmokers: 2.83 and 2.35, respectively; ORs relative to past smokers: 2.80 and 1.82, respectively), and total serum cholesterol was associated directly with incident geographic atrophy (OR: 1.08 per 10 mg/dl) and inversely with incident neovascular AMD (OR: 0.94 per 10 mg/dl). Conclusions: Pooled data support a growing body of evidence indicating that smoking is related to an increased risk of incident AMD. Current smokers were at higher risk of incident AMD than both past smokers and those who never smoked. The relationships found in this study between total serum cholesterol and incident geographic atrophy and neovascular AMD are not readily explained

New brain tumor entities emerge from molecular classification of CNS-PNETs

Summary Primitive neuroectodermal tumors of the central nervous system (CNS-PNETs) are highly aggressive, poorly differentiated embryonal tumors occurring predominantly in young children but also affecting adolescents and adults. Herein, we demonstrate that a significant proportion of institutionally diagnosed CNS-PNETs display molecular profiles indistinguishable from those of various other well-defined CNS tumor entities, facilitating diagnosis and appropriate therapy for patients with these tumors. From the remaining fraction of CNS-PNETs, we identify four new CNS tumor entities, each associated with a recurrent genetic alteration and distinct histopathological and clinical features. These new molecular entities, designated "CNS neuroblastoma with FOXR2 activation (CNS NB-FOXR2)," "CNS Ewing sarcoma family tumor with CIC alteration (CNS EFT-CIC)," "CNS high-grade neuroepithelial tumor with MN1 alteration (CNS HGNET-MN1)," and "CNS high-grade neuroepithelial tumor with BCOR alteration (CNS HGNET-BCOR)," will enable meaningful clinical trials and the development of therapeutic strategies for patients affected by poorly differentiated CNS tumors