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We describe a case of cervical cord compression due to ossified posterior longitudinal ligament in association with diffuse idiopathic skeletal hyperostosis, in a young female. Characteristic CT findings are described.

A 30 year old Malay male developed bilateral choroiditis followed by vitiligo, poliosis and canities. CT scan showed nodular thickening of the optic nerves. Characteristic abnormalities were seen in visual and brainstem auditory evoked potentials and fluorescein angiography. These findings were in keeping with the diagnosis of Vogt-Koyanagi-Harada syndrome. Treatment with dexamethasone resulted in complete recovery of vision and partial improvement in skin and hair lesions.

The clinical and electroencephalographic (EEG) features were evaluated in a consecutive series of 50 infants with complex partial seizures. The age of onset of seizures showed a peak at age of 2 months. Significant development delay was seen in 60% of the infants. In 92% an underlying aetiological factor could be identified. Birth asphyxia was the commonest aetiological factor (30%). The seizure patterns were most frequently described as behavioural arrest, upward deviation of eyes, tonic posturing of the limbs, apnoea and cyanosis. Interictal EEG showed bilateral temporal lobe foci in 22%, unilateral foci in 78% and multiple foci in 46% of the cases. The response of the seizures to anticonvulsant drugs is discussed.

A number of polycyclic aromatic sulfur heterocycles have been identified in coal-derived products and in shale oils. The mutagenic activity of some of these compounds, including dibenzothiophene, benzo[b]naphtho[1,2-d]thiophene, benzo[b]naphtho[2,1-d]thiophene and benzo[b]naphtho[2,3-d]thiophene have been determined using the Salmonella/microsome mutagenicity test. These compounds demonstrated either very weak or no mutagenic activity. The methyl derivatives of each of these four compounds were assayed for mutagenic activity. Salmonella typhimurium TA98 was used as the tester strain. All assays required a rat-liver homogenate metabolic activator. Five of the methylated derivatives, 1-methylbenzo[b]naphtho[1,2-d]thiophene, 3-methylbenzo[b]naphtho[1,2-d]thiophene, 1-methylbenzo[b]-naphtho[2,1-d]thiophene, 6-methylbenzo[b]naphtho[2,1-d]thiophene and 4-methylbenzo[b]naphtho[2,3-d]thiophene demonstrated mutagenic activity. However, activity was observed only at high concentrations of the metabolic activator.

It is shown that the invariant integral, viz., the Kolmogorov second entropy, is eminently suited to characterize EEG quantitatively. The estimation obtained for a "clinically normal" brain is compared with a previous result obtained from the EEG of a person under epileptic seizure.

The present study deals with observations on the "speech evoked potential"-a late positive potential evoked by word repetition. These potentials, evoked by "silent" repetition of polysyllabic words, were averaged and recorded from the scalp overlying the inferior frontal regions on both sides in 20 normal healthy subjects of ages ranging from 13-58 years. The potential had a triphasic negative, positive, negative morphology and was present over both hemispheres in left as well as right handed subjects. The main positive deflection and mean latencies of 219.2 msec and 221.6 msec and mean amplitude of 6.2 muv and 6.5 muv respectively on the left and right sides. Though there were interindividual variations in latency, amplitude and morphology, there was a high degree of intraindividual similarity and reproducibility in subjects. The variations in these parameters with age, sex and handedness are discussed. In 10 patients with cerebral lesions, the evoked potential was normal in 5 cases with right frontal lesions and showed abnormalities in 3 of 5 cases with left frontal lesions. The speech evoked potential may be useful in the further study of electrical correlates of speech output in speech disorders.

A theoretical model, based on response of a neural network to an external stimulus, was constructed to determine its collective modes. It is suggested that the waves observed in EEG records reflect the cooperative electrical activity of a large number of neurons. Further, an actual EEG time series was analyzed to deduce two dynamic parameters, dimension d of phase space of the neural system and the minimum number of variables nc necessary to describe the EEG pattern. We find d = 6.2 and nc = 11.

A very general model of an idealized neural network is proposed, in which the system is governed by an evolution equation. The equation determines the state of the network at time t greater than 0, if its state at time t = 0 and the kernel (in the equation) are known. It is shown that, by making specific assumptions about the kernal and the initial state, the evolution equation describes a distributed memory having the properties of recognition and association. In this case the model of the distributed memory is identical to that of Anderson and Cooper. Further, it is shown that by a different choice of the kernel, the evolution equation goes beyond the earlier model and is able to describe learning as a dynamic process.

Antithrombotic activity of ten pyrazolo pyrimidine derivatives was tested in mouse pulmonary thromboembolism model. Out of these compounds, Thiopurinol (C5H4N4S) showed dose-dependent protection in mice from death/paralysis induced by collagen + adrenaline. It also caused dose-dependent inhibition of thrombus formation in the cat. Thiopurinol inhibited aggregation of platelets induced by ADP and arachidonic acid but did not inhibit superoxide generation. It had no antiinflammatory activity nor any effect on cardiovascular system. The results indicate that the antithrombotic activity of the compound is mediated via inhibition of platelet aggregation.