Dissection of the brain supplying arteries over the life span.

Cervical artery dissection (CAD) is being increasingly diagnosed due to improved neuroimaging methods. The mean age of patients with CAD is about 40 years, with a peak between 40 and 45 years of age. Proven data on the incidence of CAD in older patients are missing. Therefore, whether CAD should also be considered as a probable cause of cerebral ischemic events in the elderly was investigated. All consecutive patients referred to our clinic with a diagnosis of cerebral ischemia from January 1999 until June 2000 were thoroughly assessed for the presence of CAD. In addition, the records of all stroke patients treated in our department from January 1995 to December 1998 were analysed retrospectively for a diagnosis of CAD. A total of 34 patients (11 women) had suffered from internal carotid (n = 29) or vertebral artery (n = 5) dissection. Their mean (SD) age was 50.3 (14.6) years, with 32.4% being older than 60 years. Clinical presentation of CAD did not differ depending on the patients' age. The results show that CAD is a possible cause of cerebral ischemia in the elderly and thus has also to be considered in the diagnostic investigation in this patient group.

Selective loss of timbre perception for keyboard and percussion instruments following a right temporal lesion.

We report the case of a 65-year-old man WDK, who experienced selective loss of timbre perception for keyboard and percussion instruments following a right temporal stroke comprising the anterior superior and medial gyrus and parts of the insular region. Formerly an avid listener to music, the sound of an orchestra appeared to be "flat" to him. WDK and a matched control subject underwent a detailed neuropsychological test battery covering basic auditory function (audiometry and just notable difference for pitch shifts), specific auditory function (recognition of environmental sounds), specific musical functions like discrimination of pitch, interval, contour, rhythm and metre, recognition of familiar melodies, emotional responsiveness, perception of timbre and auditory spectral analysis. While WDK displayed no deficits in primary auditory function, the test battery revealed a selective impairment in the perception of timbre of keyboard and percussion instruments which could be traced to a deficit in discriminating rapid changes of the spectral composition of a tone. Hence, these findings demonstrate the existence of highly specific neural networks underlying isolated aspects of timbre perception in the right anterior temporal lobe.

Effects of subthalamic nucleus (STN) stimulation on motor cortex excitability.

BACKGROUND: Deep brain stimulation of the internal global pallidus (GPi) and the subthalamic nucleus (STN) has become a treatment alternative in advanced PD. Although the effects of GPi stimulation have been examined recently, little is known about STN stimulation effects on motor cortex excitability. METHODS: The effects of STN stimulation were studied in eight patients with advanced PD using paired-pulse transcranial magnetic stimulation (TMS) in comparison with healthy control subjects. Motor evoked potentials following paired-pulse TMS (interstimulus interval 3 ms to test for corticocortical inhibition vs 13 ms for facilitation) have been recorded from the extensor carpi radialis and its functional antagonist, the flexor carpi radialis muscle. Silent period (SP) was also determined. Patients were examined under four conditions: medication "off"/stimulator "off" vs medication "on"/stimulator "off" vs medication "off"/stimulator "on" vs medication "on"/stimulator "on." RESULTS: Although the mean values for intracortical inhibition (ICI) were not significantly different, data variation was smaller and levels of significance higher with the STN stimulator switched "on," suggesting that ICI was more consistent. SP during stimulator "on"/medication "on" was longer than during stimulator "off"/medication "off." Motor performance as indicated by a finger-tapping test and Unified PD Rating Scale III was significantly better with dopaminergic medication and further improved with stimulator "on." CONCLUSIONS: Results suggest an effect of subthalamic nucleus stimulation on intracortical inhibitory mechanisms. This hypothesis could at least partially explain a more consistent depression of motor evoked potentials following inhibiting paired-pulse transcranial magnetic stimulation, a longer silent period (under stimulator "on"/medication "on"), and a reduction of akinesia and rigidity leading to a better motor performance in subthalamic nucleus-stimulated patients.

Deficit in automatic sound-change detection may underlie some music perception deficits after acute hemispheric stroke.

Music perception deficits following acute neurological damage are thought to be rare. By a newly devised test battery of music-perception skills, however, we were able to identify among a group of 12 patients with acute hemispheric stroke six patients with music perception deficits (amusia) while six others had no such deficits. In addition we recorded event-related brain potentials (ERPs) in a passive listening task with frequent standard and infrequent pitch deviants designed to elicit the mismatch negativity (MMN). The MMN in the patients with amusia was grossly reduced, while the non-amusic patients and control subjects had MMNs of equal size. These data show that amusia is quite common in unselected stroke patients. The MMN reduction suggests that amusia is related to unspecific automatic stimulus classification deficits in these patients.

Event-related brain potentials to sound omissions differ in musicians and non-musicians.

The mismatch negativity (MMN) component of the auditory event-related brain potential reflects the automatic detection of sound change. MMN to occasionally omitted sounds in a tone series can be used to investigate the time course of temporal integration in the acoustic system. We used MMN to study differences in temporal integration in musicians and non-musicians. In experiment 1, occasionally omitted 'sounds' in an otherwise regular tone series evoked a reliable MMN at interstimulus intervals (SOAs) of 100, 120, 180 and 220 ms in musicians. In non-musicians, MMN was smaller/absent in the 180 and 220 ms SOAs, respectively. In experiment 2, deviance of a tone was induced by presenting tones at a shorter SOA (100 or 130 ms) compared to the standard stimulus (150 ms). Musicians showed a reliable MMN for both deviant SOAs whereas non-musicians showed an MMN only for tones presented 50 ms prior to a standard tone (SOA 100 ms). These results indicate that the temporal window of integration seems to be longer and more precise in musicians compared to musical laypersons and that long-term training is reflected in changes in neural activity.

Strategic control of gastrointestinal nematode and lungworm infections with eprinomectin at turnout and eight weeks later.

Two groups of 10 first-year grazing cattle were either left untreated as controls (group 1) or treated with eprinomectin as a pour-on application at turnout and eight weeks later (group 2). The control group developed a mild infection with gastrointestinal nematodes and lungworms during the season, whereas the treated animals remained healthy. The interval between the treatments allowed the establishment of adult worms, but the egg counts remained negligible. The total number of eggs shed by the treated cattle during the grazing season was significantly smaller than by the controls.

Brain potentials in patients with music perception deficits: evidence for an early locus.

Twelve patients with an acute cerebrovascular accident were assigned to a group with music perception deficits (amusia, n = 6) or a group without such deficits (n = 6) on the basis of a new test-battery for music-perception skills. Event-related brain potentials (ERPs) were recorded in an auditory classification task designed to elicit several components; the N1 as a correlate of initial auditory cortical processing, the P3a as an index of automatic attentional orienting, and the P3b as a measure for controlled stimulus evaluation. Patients with amusia showed a significant amplitude decrement for the P3a relative to controls and patients without amusia suggesting an impairment of early stimulus evaluation. P3b was reduced in both patient groups relative to control. These data show that amusia is quite common in unselected stroke patients and suggest deficits of generic rather than music-specific cognitive processes as the underlying cause.

In vitro expression of a recombinant paramyosin of Ancylostoma caninum.

The objective of this study was to characterise a recombinant antigen of Ancylostoma caninum that had been identified by immunoscreening with selected antisera described elsewhere. In vitro expression of clone 341 produced a protein with an apparent molecular mass of approximately 34 kDa which was recognised in Western blots by antisera against whole worms and antisera against esophagi from adult worms, but not by sera from experimentally infected dogs or rabbits. DNA sequencing showed a cDNA of 1176 bp coding for a 34-kDa protein, similar to the size identified in the immunoblot. DNA database comparison revealed an 80-82% homology with the Caenorhabditis elegans unc-15 gene coding for paramyosin. The deduced aa sequence of clone 341 showed 95% homology with the paramyosin aa sequence of C. elegans. Affinity purified antibodies against the recombinant protein recognise a protein with an apparent molecular mass of 97 kDa of A. caninum muscle tissue fraction which is in accordance with the molecular mass of paramyosin from Schistosoma mansoni and Schistosoma japonicum.

A recombinant protein disulfide isomerase homologue from Ancylostoma caninum.

The objective of this study was to characterize a recombinant antigen of Ancylostoma caninum that had been identified by immunoscreening with selected antisera as described elsewhere. In vitro expression of clone Ac38-1 produced a protein with an apparent molecular mass of approximately 38 kDa, which reacted in Western blots with the antiserum from rabbits experimentally infected with L3 and also with affinity-purified antibodies against hydrophilic proteins of the cephalic glands obtained from the antiserum against the intestine, cephalic glands, and cervical glands of adult worms. It was recognized not by antisera from dogs percutaneously infected with 1,000 L3 of A. caninum but by antiserum from dogs infected with 100,000 L3 of A. caninum. DNA sequencing of clone Ac38-1 showed a cDNA fragment with a coding region of 1,014 bp. Comparison of clone Ac38-1 with the Genbank DNA data base revealed 78% identity with a 244-bp segment of the cm5b5 clone of the free-living nematode Caenorhabditis elegans coding for a protein disulfide isomerase gene. The deduced amino acid sequence of clone Ac38-1 showed 82% identity with a 334-amino-acid (aa) segment of the protein disulfide isomerase of C. elegans and 73% identity with a 334-aa segment of the protein disulfide isomerase aa sequence of Onchocerca volvulus.

The development of protective immunity against gastrointestinal nematode and lungworm infections after use of an ivermectin bolus in first-year grazing calves.

Interactions between treatment with an ivermectin bolus at turnout and immunity to bovine parasitic gastroenteritis and bronchitis were examined. Immunity related parameters, i.e. development of clinical disease, parasite development and stimulation of parasite specific antibodies were examined for two grazing seasons and compared with untreated second season cattle (immune control) and untreated parasite naive cattle (nonimmune control). With respect to gastrointestinal nematodes, clinical condition, body weight development, faecal egg counts and pepsinogen concentrations of the bolus treated animals were not significantly different from the respective values of untreated immune cattle, showing a considerable degree of resistance in both groups compared to the parasite naive cattle. With respect to lungworms, untreated immune cattle were protected against clinical disease, but two of eight animals shed larvae again. Bolus treated animals transiently showed mild clinical symptoms and six of seven animals shed low numbers of larvae again, whereas all parasite naive cattle shed high numbers of lungworm larvae and showed signs of disease during the whole grazing season. In spite of the effective treatment with an ivermectin bolus during the first year a considerable resistance to gastrointestinal nematode and lungworm infection was present in the second grazing season.

Immunochemical characterization of Ancylostoma caninum antigens.

Adult worms of Ancylostoma caninum were dissected and manually separated into cephalic glands, cervical glands, intestine, esophagus and cuticula. These fractions as well as third stage larvae were fractionated with Triton X-114 into water soluble (hydrophilic), Triton soluble (hydrophobic) and unsoluble proteins. These fractions were characterized by immunoblotting with serum from rabbits immunized either with a pool of cervical, cephalic glands and intestine, or the esophagus fraction as well as with sera from percutaneously infected dogs and rabbits. Immunodominant antigens were found that reacted with dog or rabbit post infection sera and could be suited as antigens in serodiagnostic tests. Hidden antigens were found in the several fractions. Those from esophagus and intestine could be vaccine candidates that will be tested in immunization trials.

Use of an ivermectin bolus against gastrointestinal nematode and lungworm infections in first-year grazing calves.

Two groups of first-year grazing cattle each were either left untreated as controls (group 1) or treated with an ivermectin bolus at turnout (group 2). Whereas group 1 suffered from dictyocaulosis, the bolus treated calves remained healthy. Shedding of lungworm larvae was completed prevented and gastrointestinal nematode egg output effectively reduced. During the 154 day grazing season the ivermectin bolus provided a season-long protection against parasitic gastroenteritis and bronchitis.