Triangle Singularity as the Origin of the a_{1}(1420)

The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a_{1}(1420), decaying to f_{0}(980)π. With a mass too close to and a width smaller than the axial-vector ground state a_{1}(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a_{1}(1260) resonance into K^{*}(→Kπ)K[over ¯] and subsequent rescattering through a triangle singularity into the coupled f_{0}(980)π channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the light-meson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect.

First Measurement of Transverse-Spin-Dependent Azimuthal Asymmetries in the Drell-Yan Process

The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190  GeV/c π^{-} beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3  GeV/c^{2} and 8.5  GeV/c^{2}. Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.

[The first year of use of the Leksell gamma knife at the Hospital Na Homolce--results after 5 years]

The first Leksell gamma knife procedure was performed in Prague on 26th October 1992 and during the first year 156 patients were treated at the department of stereotactic and radiation neurosurgery. 42% patients suffered from a vascular lesion, 39% of patients from a benign tumour and 19% patients from a malignant tumour. Radiosurgery using the gamma knife is a non-invasive stereotactic neurosurgical procedure. Radiosurgery, as microsurgery, must be evaluated not only early, but also the late effect after the treatment some years. Evaluation of the results is therefore an ongoing process and results of the first year with the 5-year follow up are presented. At this time radiosurgery has a zero treatment mortality and the present morbidity with regard to the diagnosis 0-10%.

[The Leksell gamma knife--a radiosurgery instrument]

Radiosurgery means delivery of a single dose of precisely directed ionizing radiation to a small volume of intracranial tissue without opening of the skull after the stereotactic localisation of the preselected target. Leksell gamma knife is a device enabling to deliver focused radiation toward the intracranial volume with the gamma rays emitted by the 201 sources of the isotope Co 60. Suitable indications for radiosurgery are cerebral arteriovenous malformations, benign and malignant intracranial tumors and functional diseases of the brain.

[Use of the radiosurgery knife in the treatment of hypophyseal adenomas]

BACKGROUND. Surgery of pituitary adenomas did not produce quite satisfactory results. Therefore radiosurgery using Leksell's gamma knife has become the most widely used method which-with the contribution of MRI-meets the most important demands of aimed irradiation: a sufficiently high dose of radiation of the tumour and minimal radiation load of functionally important surrounding structures. The objective of the investigation was to assemble experience with this therapeutic method. METHODS AND RESULTS. During the period between October 1992 and September 1994 a total of 41 patients were treated: 16 men, 12-66 years old, mean age 40.8 years; 25 women age 16-76 years, mean age 50.2 years. Female:male ratio 1.5 : 1. In 30 patients (73.2%) a microsurgical operation had preceded, in 5 (12.2%) conventional fractionated radiotherapy and in 11 patients (26.9%) primary radiosurgery. As far as the type of pituitary adenoma is concerned, it conditioned acromegaly in 30, Cushing's syndrome in 3 or Nelson's syndrome in 1, or a prolactinoma was involved (in 2 patients). In five instances the adenoma was hormonally inactive. Its localization was most frequently intrasellar (36), less frequently parasellar (5). The range of administered doses varied as regards the maximum between 12.5 and 80 Gy, the average being 46.8 Gy, to the periphery of the adenoma a dose of 10-49 Gy was administered, on average 24.7 Gy using a 50-80% isodose. The time interval after treatment is relatively short for detailed analysis or evaluation. During current evaluation the authors did not observe in any of the patients progression of the disease, and in several patients diminution of the tumour was found. Karnofski's score seemed to improve. CONCLUSIONS. Radiosurgery, using Leksell's gamma knife, is after failure of conservative and microsurgical therapeutic possibilities suitable further treatment of pituitary adenoma. In indicated cases it may be the first choice. Postirradiation follow up indicates promising effects, for more detailed evaluation a several years' interval is necessary.

[Radiosurgery with the gamma knife]

The conception of radiosurgery now more than 40 years old is realized in clinical practice during last 25 years. There were elaborated 3 main methods: focused irradiation by gamma knife, by accelerated heavy charged particles and by linear accelerator. The results led radiosurgery spread over the world. The main indications are vascular malformations (44%), benign intracranial tumours (33%), malignant tumours including metastasis (21%) and functional disorders (2%). The pathological lesions can be controlled or liquidated in 80-95%. The hospital story is minimal, 1-2 days, and there is no risk of mortality and morbidity is minimal. Only the time of healing is prolonged to some years with indispensable follow-up. Further technical improvement and growing number of patients treated by radiosurgery can be expected.

[Detection of cerebropathy in neurologic and psychiatric diseases]

The authors made a comprehensive examination of 16 patients--epileptics, alcoholics, psychotic subjects and patients after cerebral contusion. The patients were subjected to a neurological, psychiatric, psychological examination as well as to a morphological examination (X-ray, CT, NMR), physiological examination (EEG, polysomnography, evoked potentials), immunological examination and SPECT. The majority of patients had positive CT and SPECT findings suggesting focal brain damage. These results could be explained only in exceptional cases by injury, the majority was of unknown aetiology. With this corresponded focal EEG abnormalities and in particular sleep disorders, sometimes subjective but always detectable by objective methods. There was always a shortage of REM, sometimes also NONREM sleep. Half the patients were subjected to an immunological examination which was always positive and comprised elevated acute stage proteins and proteins associated with the stress reaction. Numerous data in the literature and the authors' experience indicate that the mentioned pathological findings are not incidental and form, independently on the aetiology, an integrated unit for which the term cerebropathy can be used. A primary role is played by the epileptic focus and its quality, i.e. above all the rate of discharge and site and humoroergic systems of the brain stem, in particular their efficiency and mutual balance. The events have a programmed sequence. At the beginning an epileptic focus develops which influences the surrounding area, secondary and tertiary foci are formed and the thalamo-cortical system is affected. Soon this is followed by an apparent influence of the epileptic activity on structures of the brain-stem. The consequence are changes affecting sleep, mood, mental performance, immunity, endosecretion and paroxysms. Subsequently individual symptoms are already prepared but have a different latency of manifestation and the latter depends also on external provoking influences. The thalamo-cortical reaction is characterized by the manifestation of epileptic paroxysms and sets in after a different interindividual incubation following injury. The same applies to the hippocampal reaction manifested by the organic psychosyndrome. Some symptoms such as changes of immunity, sleep or endosecretory function are not necessarily manifested if the influence of the focus on structures of the brain-stem is not sufficiently intense. Conversely if the effect on the brain-stem and limbic structures is greater and the effect on the thalamo-cortical system smaller, psychotiform behaviour develops. Then there are marked changes of phoria, dynamogeny, rate, affectivity, sleep and hormonal secretion and its equilibrium.

Neurohumoral relations in neurological and psychiatric patients

Sixteen patients-epileptics, alcoholics, psychotics and post-contusion cases-were subjected to neurological, psychiatric, psychological, morphological (X-ray, CT, NMR), physiological (EEG, polysomnography, evoked potentials), immunological and SPECT examination. Most had CT and SPECT signs of focal brain damage. The results were but exceptionally due to injury, most were of unknown etiology. This tallied with EEG focal abnormalities, mainly sleep disorders, sometimes subjective ones, but invariably detectable objectively. In each case there was REM, in some also NONREM sleep deficiency. Half of the cases were tested immunologically, each time with positive results: increased levels of acute-phase protein and stress-reaction proteins. As copious literature and our experience show, the above pathological condition, rather than being accidental, constitute regardless of etiology, an integrated entity which could be called "programme cerebropathy". The primary role is played there by the epileptic focus and its properties, in particular, the speed of discharge and localization and brain stem humoroergic systems, i.e., their performance and mutual balance. There is a program sequence of events, first, and epileptic focus acting on the neighborhood, the rise of secondary and tertiary foci, and influence over the thalamocortical system. Soon afterwards, epileptic activity begins to act on brain-stem structures. This results in changes in sleep, mood, psychic output, immunity, endosecretion, and in paroxysms.

[Consciousness and the electroencephalogram]

In the course of 12 years the authors subjected to clinical EEG and stereo-EEG (SEEG) 72 patients (66 epileptics with the diagnosis of psychomotor epilepsy and grand mal) and six psychotic patients suffering from schizophrenia. With the exception of five epileptics and two psychotic patients all subjects had epileptic foci in the amygdalohippocampal complex (AHK). After coagulation of these foci marked improvement of the fits and the mental state occurred in half the patients. During EEG and SEEG recording the authors used different activation methods (hyperventilation through the nose and mouth, sleep, listening to music) and above all direct electric stimulation (ES) of one of the AHK. Secondary epileptic foci had, as a rule, more spikes and a lower threshold for ES than primary ones which contained more delta and slow theta waves. The ES led as a rule to an emotional response, such as anxiety and fear, more rarely to illusions, depersonalization and oneiroid hallucinations and twice to a hedonic response of non-sexual character. The purpose of ES was to assess the site from where it is possible to start the original aura or typical parox. The authors considered these foci, consistent with data in the literature, as the leading focus and it was subsequently coagulated. The authors investigated the reactivity and vigility by the patient's response to sound (the patient had to press a button) and by an interview with the patient. It was revealed that in isolated discharges of the spikes and waves in the scalp electrodes, i.e. in the neocortex, reactivity is lacking. In isolated discharges in the AHK the reactivity was satisfactory, but as a rule anxiety developed. It is thus possible to divide consciousness into emotional consciousness with its site in the AHK, i.e. in the limbic system, and rational consciousness which is a function of the neocrotical system. Congenital changes of consciousness such as vigility or sleep are described as "states" of consciousness. The rational or emotional aspect of behaviour is described as "type" of consciousness. Under normal conditions the states of consciousness alternate periodically and are sharply defined, the types of consciousness are closely linked and are difficult to separate. Under pathological conditions the "states" of consciousness differ less markedly and the "types" of consciousness are in dissociation. Thus obnubilation, depersonalization, illusions, pathic affects etc. develop, as a rule as part of the epileptiform or psychotiform syndrome.

Grafting of fetal dopamine neurons in Parkinson's disease. The Czech experience with severe akinetic patients

Preliminary results in three patients with Parkinson's disease, who had transplantation of human embryonic mesencephalic tissue into the caput nuclei caudati, are reported. Some improvement was achieved.

[Instruments used in various operations in the area of the gasserian ganglion]

The authors describe instruments which make it possible to perform retrogasserian thermolesions (RGT), glycerol radiculolysis (GRL) or trigeminal balloon compression (TBC) or possibly a combination of these methods from a single surgical approach. This makes it possible to adjust the selection of the type of lesion to unforeseen conditions any time during the operation. The surgical results are compared in 308 RGT, 50 GRL and 22 TBC. There are no substantial differences and therefore the selection of the type of lesion depends on technical circumstances during operation.