Experimental findings on the nasal tract resonator in singing.

SUMMARY: Many professional operatic singers sing the vowel /a/ with a velopharyngeal opening.(1) Here resonatory effects of such an opening are analyzed. On the basis of CAT scan imaging of a baritone singer's vocal tract and nasal cavity system, including the maxillary sinuses, acoustic epoxy models were constructed, in which velopharyngeal openings were modeled by different tubes. The sound transfer characteristics of this model were determined by means of sine-tone sweep measurements. In an idealized (iron tube) model, the VPO introduced a zero in the transfer function at the frequency of the nasal resonance. In the epoxy models, however, the resonances of the nasal system, and hence the zero, were heavily damped, particularly when the maxillary sinuses were included in the nasal system. A velopharyngeal opening was found to attenuate the first formant in /a/, such that the relative level of the singer's formant increased. A similar effect was observed in a modified epoxy model shaped to approximate the vocal tract of an /u/ and an /i/, although it also showed a substantial widening of the first formant bandwidth. Varying the size of the velopharyngeal opening affected the transfer function only slightly. It seems likely that singers can enhance higher spectrum partials by a careful tuning of a velopharyngeal opening.

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector.

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

[Thrombolytic treatment of acute cerebral infarction]. / Trombolysebehandling af akut cerebralt infarkt.

INTRODUCTION: Thrombolytic therapy of acute ischaemic stroke within three hours of the onset of symptoms is approved by health authorities in the USA and Canada, but not in Europe. METHODS: We report seven patients treated with recombinant tissue plasminogen activator (rtPA) within three hours of the onset of stroke according to an open protocol following internationally accepted guidelines. RESULTS: Three patients with initial severe neurological deficits made an almost complete recovery within the first 24 hours after treatment. Two patients had a partial remission, and two patients had no benefit. There were no bleeding complications. DISCUSSION: The present results are in accordance with the Cochrane Library's analysis of published data regarding thrombolytic therapy.

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice.

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.

Computer tomographic and radiographic changes in the temporomandibular joints of two young adults with occlusal asymmetry, treated with the Herbst appliance.

Two young patients, one female and one male, with asymmetric occlusal deviation and extreme Angle Class II division 1 malocclusions were treated with the Herbst appliance after cessation of endochondral growth (union of the radius epiphysis). During treatment, computer tomographic (CT) scanning and orthopantomograms of the temporomandibular joints (TMJs) revealed, as a result of bone modelling, asymmetrical new bone formation as a double contour on the distocranial part of the condyles. The treatment results were followed for more than 2 years and the new bone was found to be stable.

Progressive atrophy of the frontal lobes in first-episode schizophrenia: interaction with clinical course and neuroleptic treatment.

OBJECTIVE: This prospective study examined the interaction of clinical course of disease and brain structure with time in schizophrenic patients. METHOD: A total of 21 first-episode schizophrenic patients, 10 patients with other psychiatric disorders and a control group of 9 healthy volunteers had CT at first admission and at reinvestigation 5 years later. RESULTS: At first admission all of the patients had enlarged cortical fissures and sulci compared to controls, and the duration of untreated psychosis was significantly correlated with sulcal enlargement. At reinvestigation, frontal and central brain atrophy had progressed in schizophrenic patients. CONCLUSION: The study indicated that ongoing psychosis and lifetime dose of classical antipsychotics were the main candidates accounting for the finding of progressively disturbed brain structure during the first 5 years of schizophrenia.

In situ measurements of optical parameters in Lake Baikal with the help of a Neutrino telescope.

We present results of an experiment performed in Lake Baikal at a depth of approximately 1 km. The photomultipliers of an underwater neutrino telescope under construction at this site were illuminated by a distant laser. The experiment not only provided a useful cross-check of the time calibration of the detector but also allowed us to determine inherent optical parameters of the water in a way that was complementary to standard methods. In 1997 we measured an absorption length of 22 m and an asymptotic attenuation length of 18 m. The effective scattering length was measured as 480 m. By use of (cos theta) = 0.95 (0.90) for the average scattering angle, this length corresponds to a geometric scattering length of 24 (48) m.

[CT-guided spinal biopsy in spondylodiscitis]. / CT-vejledt borebiopsi ved spondylodiscitis.

Since February 1987 percutaneous CT-guided spine biopsy was performed in 18 patients with spondylodiscitis at the X-ray Department of Bispebjerg Hospital. Eleven cases were spontaneous and seven followed spinal surgery. The infection was located in five cases in the thoracic spine and in 13 cases in the lumbar spine. Only one biopsy was performed during general anaesthesia, the rest under local anaesthesia. No complications were observed. The bioptic material was cultivated immediately beside the patient and incubated for 14 days. The infective organism was isolated in 12 cases (67%). Thus, material obtained through a fine needle was satisfactory for microbiological investigation. A biopsy is crucial for establishing a microbiological diagnosis and thereby enabling prompt adequate treatment.

[Spontaneous and postoperative spondylodiscitis. A material concerning 23 patients]. / Spontan og postoperativ spondylodiscitis. Et materiale på 23 patienter.

A retrospective study of 23 patients with spondylodiscitis is reported. Sixteen cases were spontaneous. Five of these were seen in the acute phase with S. aureus grown from the blood. Eleven patients were investigated with CT-guided biopsy of the spine with identification of different microorganisms in eight cases. In four of seven cases of spondylodiscitis after operation for disc herniation coagulase-negative staphyloccoci were grown after CT-guided biopsy. In spontaneous cases pain disappeared and CRP was normalized within a few weeks after treatment with antibiotics, but radiological changes might progress for several months. Antibiotics were given for two to six months, with a mean of 5.1 months in purulent bacterial infections, and all patients were considered cured after this.

Optical properties of deep ice at the South Pole: absorption.

We discuss recent measurements of the wavelength-dependent absorption coefficients in deep South Pole ice. The method uses transit-time distributions of pulses from a variable-frequency laser sent between emitters and receivers embedded in the ice. At depths of 800-1000 m scattering is dominated by residual air bubbles, whereas absorption occurs both in ice itself and in insoluble impurities. The absorption coefficient increases approximately exponentially with wavelength in the measured interval 410-610 nm. At the shortest wavelength our value is approximately a factor 20 below previous values obtained for laboratory ice and lake ice; with increasing wavelength the discrepancy with previous measurements decreases. At ~415 to ~500 nm the experimental uncertainties are small enough for us to resolve an extrinsic contribution to absorption in ice: submicrometer dust particles contribute by an amount that increases with depth and corresponds well with the expected increase seen near the Last Glacial Maximum in Vostok and Dome C ice cores. The laser pulse method allows remote mapping of gross structure in dust concentration as a function of depth in glacial ice.

Microbiologically verified diagnosis of infectious spondylitis using CT-guided fine needle biopsy.

Using a computed tomography (CT)-guided technique we have been able to obtain fine needle spine biopsies directly from an affected vertebra or disk plate in 14 patients suspected of infectious spondylitis. The bioptic material was cultivated immediately and incubated for 14 days. Cultures from eight patients were positive. No single microbiological agent was predominant though coagulase-negative staphylococci were frequent. In no case were mycobacteria found. Bioptic material from six patients did not give rise to growth of microorganisms. We were able to successfully treat the eight patients with a culture-positive biopsy. We think that biopsies are crucial for establishing a microbiological diagnosis. The whole procedure takes less than one hour; it is performed under local anaesthesia and is thus not very stressful for the patient: The success rate for obtaining a positive spine biopsy was 57%.

CT-scanning and radiographic analysis of temporomandibular joints and cephalometric analysis in a case of Herbst treatment in late puberty.

From a consecutive sample of 100 patients treated with the Herbst appliance after the peak of puberal growth, a boy was chosen to show the total effect of the Herbst treatment. Changes in the dentofacial morphology and the structure of the temporomandibular joints (TMJ) were followed by radiologic examinations and the function of the craniomandibular system was studied by clinical examinations, and electromyographic and bite-force recordings. Treatment resulted in marked dentoalveolar changes, an increase of mandibular length, ramus height, and gonion angle. Three months after insertion of the appliance CT-scanning and orthopantomograms of the TMJ revealed new bone formation as a double contour in the fossa articularis and on the posterior part of the condylar process as a result of adaptive bone remodelling. Function was affected by treatment, but was markedly restored at control.

Relationship between brain structure and function in disorders of the schizophrenic spectrum: single positron emission computerized tomography, computerized tomography and psychopathology of first episodes.

Fifty newly diagnosed, briefly treated or drug-naive patients with schizophrenia or schizophreniform disorder were examined by psychopathology scales for positive (SAPS), negative (SANS) and overall psychotic symptoms (PSE and BPRS). CT-scan and regional cerebral blood flow (rCBF) measurement by 99mTc-HMPAO SPECT during rest and mental activation by Wisconsin Card Sorting Test was performed as well. Twenty-five age-matched normal healthy volunteers served as controls. Thought disorders and fundamental symptoms correlated positively with relatively high, though subnormal prefrontal (PFC) rCBF and high rCBF in temporal cortex; positive symptoms correlated positively with high rCBF in the striatum and temporal cortex during activation. Negative symptoms correlated with high prefrontal rCBF. The patients had sulcal enlargement and smaller brain volume compared with the healthy volunteers. There were no signs of ventricular enlargement. Neither total negative symptoms, thought disorder nor fundamental symptoms correlated with any CT measurements. Total positive symptoms correlated negatively with the size of the temporal horns. The relatively high rCBF in PFC and temporal cortex of cases with pronounced positive and negative symptoms and thought disorder may imply that an aberrant cortical network has to be active to express a malattuned clinical output. The striatal hyperfunction mainly in productive cases may be a secondary phenomenon and more pronounced in cases where no signs of subcortical atrophy has (yet?) ensued.

Cerebral oxygen extraction, oxygen consumption, and regional cerebral blood flow during the aura phase of migraine.

BACKGROUND AND PURPOSE: The aura phase of migraine is associated with focal blood flow changes, but it has been largely unknown whether these changes are correlated to changes in the cerebral metabolism. METHODS: Eight patients required carotid angiography for evaluation of transient neurological attacks. Cerebral blood flow (CBF) results, angiography, and clinical observations subsequently suggested the diagnosis: migraine with aura and occasional aura attacks without headache. In the same setting the cerebral angiography was followed by four to six repeated recordings of regional CBF using the intra-arterial 133Xe injection method. Blood samples were drawn from the carotid artery and the internal jugular vein to measure oxygen extraction fraction and cerebral metabolic rate for oxygen. RESULTS: The intracarotid regional CBF technique provoked aura symptoms and typical, migraine-related, posterior focal hypoperfusion in four patients, followed by typical unilateral headache in three patients. The remaining four patients had no symptoms or regional CBF changes during the examination. There was a significant increase (mean, 13%) of global oxygen extraction fraction in the four patients during aura symptoms, whereas no significant changes of oxygen extraction fraction were found in the nonsymptomatic group. The increase in global oxygen extraction fraction in the symptomatic group coincided with a drop of hemispheric CBF (mean, 12%). Cerebral metabolic oxygen rate remained essentially unchanged, as did PaCO2. CONCLUSIONS: The data presented suggest that the focal flow reduction during the migraine-aura phase is not a secondary phenomenon of reduced cerebral metabolism. However, arteriolar vasoconstriction might offer a possible explanation for the regional CBF changes observed during the migraine aura.

Absence of vasoactive peptide release from brain to cerebral circulation during onset of migraine with aura.

In eight patients carotid angiography was required for evaluation of transient neurological attacks. Cerebral blood flow results, angiography and clinical observations subsequently suggested the diagnosis of migraine. We measured plasma concentrations of substance P(SP), neuropeptide Y (NPY), calcitonin gene-related peptide (CGRP) and vasoactive intestinal peptide (VIP) in repeated blood samples obtained from the carotid artery and the internal jugular vein in conjunction with cerebral angiography followed by 4 to 6 repeated recordings of regional cerebral blood flow (rCBF) with the intracarotid Xenon-133 injection technique. This technique is known to induce attacks of migraine with aura in many sufferers. Four patients developed aura symptoms. In three this was succeeded by throbbing headache. Typical, migraine-related, focal hypoperfusion occurred in conjunction with the aura symptoms. The remaining four patients had no symptoms or rCBF changes. There were no systematic or statistically significant changes over time in arterial-venous plasma concentrations or in the release rates of any of the peptides. All migraineurs had an overall elevated mean CGRP value compared to control values from the literature. The overall plasma levels of the potent vasoconstrictor NPY were higher (p < 0.10) in the group that developed symptoms and rCBF changes (136 pmol/l) than in the non-symptomatic group (97 pmol/l). The difference in NPY levels could perhaps be associated with the focal rCBF decrease seen in the attack group.

Computerised tomography in newly diagnosed schizophrenia and schizophreniform disorder. A controlled blind study.

Patients with newly diagnosed schizophrenia (n = 27) or schizophreniform disorder (n = 22) and 24 healthy volunteers were investigated by CT scan, the investigators being blind to subject status. The patients had never received medication or had been treated only briefly with neuroleptics. The patients had significantly smaller brain volume and brain length than the controls. The patients had greater sulcal enlargement in the case of both Sylvian and interhemispheric fissures and surface sulci in the frontal and parietal regions. The sulcal enlargement was more pronounced in male patients and on the left hemisphere. The study revealed no enlargement of the lateral ventricles and only a trend towards enlargement of the third ventricle in the patients. The findings were not explained by substance abuse or level of education.

Thrombolytic therapy in acute ischemic stroke. A Danish pilot study.

BACKGROUND AND PURPOSE: In a feasibility and safety study of thrombolytic therapy in acute ischemic stroke, we explored the usefulness of measurements of regional cerebral blood flow. METHODS: Twenty-three patients with acute ischemic stroke were treated with 100 mg recombinant tissue plasminogen activator infused intravenously over 1 hour. Thrombolytic therapy was initiated 78 to 355 minutes after onset of symptoms. RESULTS: Angiography 16 to 24 hours after treatment in 17 patients showed patient intracranial arteries in 12, partial occlusion of the middle cerebral artery in 3, and total occlusion of the middle cerebral artery in 2. rCBF with 99mTc-hexamethylpropyleneamine oxime intravenously was measured 5 minutes before and within 24 hours after thrombolytic therapy in 12 patients. 10 of the 12 patients showed brain tissue reperfusion and 2, with angiographically documented middle cerebral artery occlusion, showed no reperfusion, thus documenting a relationship between reperfusion measured by regional cerebral blood flow and angiographic patency (P = .015). Three patients died. Patients who were reperfused within 24 hours (documented by repeated regional cerebral blood flow measurements) showed greater clinical improvement on the Scandinavian Stroke Scale the sooner their thrombolytic therapy was started and the more severe their neurological deficits. CONCLUSIONS: Acute cerebral ischemia can be documented by rCBF measurements without delay of thrombolytic therapy, and repeated rCBF measurements can reveal whether cerebral reperfusion has occurred. In our study, early reperfusion was associated with clinical improvement.

Ischaemia-induced (symptomatic) migraine attacks may be more frequent than migraine-induced ischaemic insults.

Fifteen consecutive patients with a diagnostic problem of ischaemia-induced migraine with aura (symptomatic migraine) or migraine-associated ischaemia (migrainous infarction) were studied in order to elucidate the mechanisms. Three had a 1 month flurry of daily attacks of migraine auras with or without headache. A severe internal carotid stenosis/occlusion and reduced regional cerebral blood flow (rCBF) was demonstrated. Borderline ischaemia may thus prime the brain for developing migrainous aura with or without migraine (symptomatic migraine). Four patients had a combination of permanent deficits after the very first migraine attack, severe atherosclerosis, risk factors for stroke, high age and no family history of migraine. In these cases the evidence indicates that thromboembolic ischaemia had triggered an attack of migraine with aura (likely symptomatic migraine). Three young females presented long-lasting typical and severe idiopathic migraine with aura. Attack-associated rCBF reduction was likely to have caused permanent, mild, visual or somatosensory deficits (migrainous infarction). In five patients the relationship between migraine and stroke remained unresolved. It seems that ischaemia-induced migraine attacks may be more frequent than migraine-induced ischaemic insults. Therefore, migraine is not as strong a risk factor for stroke as indicated by the mere coincidence of the two disorders.

Severe low-back pain. II: Changes in CT scans in the acute phase and after long-term observation.

No significant changes were noted in the CT-scan before and after 14 days of conservative therapy for low-back pain. Twenty of 33 patients had a disc herniation diagnosed on CT, and of these 18 patients were re-scanned after two weeks. Twelve patients were subsequently treated surgically, and of the remaining 8 patients 6 were re-scanned after 18 months. At this time the disc herniation had diminished significantly and was located in a more median position. In the 8 conservatively treated patients, the pain score at follow-up was related to the original size of the herniation (r = 0.72, p < 0.05).