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Biomedical subjects

T Brandt

Publications and source records attributed to T Brandt.

At least 163 records · Page 9Linked to original sources
PubMed1996

Torsional nystagmus during vertical pursuit.

We examined three patients with cavernous angioma within the middle cerebellar peduncle. Each patient had an unusual ocular motor finding: the appearance of a strong torsional nystagmus during vertical pursuit. The uncalled-for torsion changed direction when vertical pursuit changed direction. In one patient, we recorded eye movements with the magnetic field technique using a combined direction and torsion eye coil. The slow-phase velocity of the inappropriate torsional nystagmus was linearly related to the slow-phase velocity of vertical smooth pursuit, and changed direction when vertical pursuit changed direction. This torsional nystagmus also appeared during fixation suppression of the vertical vestibulo-ocular reflex (VOR), but was minimal during vertical head rotation when fixing a stationary target in the light. We suggest that inappropriately directed eye movements during pursuit might be another ocular motor sign of cerebellar dysfunction. Furthermore, we speculate that the signals used for vertical smooth pursuit are, at some stage, encoded in a semicircular canal VOR coordinate framework. To illustrate, for the vertical semicircular canals, vertical and torsional motion are combined on the same cells, with the anterior semicircular canals mediating upward movements and the posterior semicircular canals mediating downward movements. For the right labyrinth, however, both vertical semicircular canals produce clockwise slow phases (ipsilateral eye intorts, contralateral eye extorts). The opposite is true for the vertical semicircular canals in the left labyrinth; counterclockwise slow phases are produced. Hence, to generate a pure vertical VOR, the anterior or posterior semicircular canals on both sides of the head must be excited so that opposite-directed torsional components cancel. Thus, if pursuit were organized in a way similar to the VOR, pure vertical pursuit would require that oppositely-directed torsional components cancel in normals. If this did not happen, a residual torsional nystagmus could appear during attempted vertical pursuit.

Adult↗
PubMed1996

Severe stroke.

Severe stroke is an emergency and requires rapid neurological assessment and diagnosis. CT scan is the first diagnostic step with the aim of finding out the extent, localization and possible pathophysiology of ischaemia in order to direct specific diagnostic and therapeutic options. An intracranial haemorrhage must be excluded. Early CT signs, including the size of the hypodensity and brain swelling, are important prognostic markers. Extracranial and transcranial Doppler sonography are valid for primary assessment of vascular pathophysiology and haemodynamics in most cases. Cerebral angiography should be performed if acute occlusion of the basilar artery or middle cerebral artery trunk is suspected and intra-arterial thrombolysis is a potential therapy. Intravenous thrombolyis has been proven to be effective in improving outcome in severe stroke; it is safe if the exclusion criteria are strictly applied. Prevention of secondary complications of stroke include general medical treatment with control of blood pressure, infections and cardiac and respiratory function, anti-coagulation. anti-oedematous treatment and surgical decompressive therapy for cerebellar and MCA space-occupying infarcts. Monitoring in the ICU is recommended. The medical therapy of intracerebral haemorrhage consists of control of ventilation and blood pressure, seizure prevention and anti-oedema treatment. Treatment of secondary ICH due to anti-coagulation or thrombolysis consists of administration of specific antidotes and the correction of the coagulopathy. Ventricular drainage should be performed when there is marked ventricular dilatation due to obstruction or blood in the ventricles. Most patients with cerebellar haemorrhage of more than 3 cm in diameter should undergo surgery to avoid brain-stem compression and hydrocephalus. In younger patients, non-dominant hemisphere putaminal and lobar haemorrhages with lateral displacement of midline structures and extensive oedema should be evacuated if the patient's level of consciousness deteriorates rapidly, or if the elevation of ICP cannot be controlled pharmacologically, and herniation is incipient. New techniques such as stereotactic and endoscopic evacuation still need to be tested prospectively. Patient selection for surgery should be cautious considering age, clinical status and possible contraindications such as cerebral amyloid angiopathy and coagulation disorders. Stroke therapy is rapidly becoming a focus of research and major changes in diagnostic and therapeutic options can therefore be expected.

Cerebral Hemorrhage↗
PubMed1995

Vestibulo-ocular reflex.

Recent animal and clinical studies on the vestibulo-ocular reflex deal with a number of physiological and clinical aspects from which three were chosen for this review: (1) the torsional vestibulo-ocular reflex and its disorders; (2) the otolith contribution to the vestibulo-ocular reflex; and (3) neurotransmitters, neuropharmacological aspects, and medical treatment. Disorders of the vestibulo-ocular reflex can be classified according to the three major planes of action, yaw plane, pitch plane, and roll plane, which equate with horizontal nystagmus, upbeat or downbeat nystagmus, and torsional nystagmus, respectively. The particular interest in the torsional vestibulo-ocular reflex arises from new methods for measuring ocular torsion, especially the three-dimensional eye-movement recordings with scleral coils. These methods make it possible to do three-dimensional analysis of the differential effects of horizontal and vertical semicircular canal function and their individual disorders of the torsional vestibulo-ocular reflex. Otolith and semicircular canal inputs converge at the level of the vestibular nuclei to subserve static graviceptive and dynamic torsional and pitch function. The elaboration of the particular sensorial weight of the input from either the otoliths or the semicircular canal is currently a challenge for both physiologists and neurologists. Disorders of otolith function, still absent from the diagnostic repertoire of most neurologists, are increasingly being reported. The most promising developments in therapeutic measures may come from research on vestibular neurotransmitters, their agonists and antagonists. A number of pharmacological agents are effective suppressants of pathological eye movements. However, systematic prospective studies are needed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

DNA concentration and length in sputum of patients with cystic fibrosis during inhalation with recombinant human DNase.

BACKGROUND: The clinical benefit of the administration of aerosolised recombinant human DNase (rhDNase) on pulmonary function in patients with cystic fibrosis has already been demonstrated but the biochemical action of rhDNase on DNA in bronchial secretions in vivo has not yet been investigated. METHODS: Sputum was collected from 135 patients with cystic fibrosis before and during treatment with aerosolised rhDNase and examined to ascertain DNA concentration and length by colorimetric assay and densitometry of gel separated DNA. RESULTS: Treatment with rhDNase reduced the concentration and the size of extracellular DNA in the sputum. The median interquartile range of DNA length decreased from 0.5-2.6 kbp before treatment to 0.3-1.0 kbp during treatment. CONCLUSIONS: rhDNase was delivered to the secretions and was enzymatically active in vivo.

Cystic Fibrosis↗
PubMed1995

Rotational vertigo in embolic stroke of the vestibular and auditory cortices.

We describe the unique case of a woman with embolic infarction within the right middle cerebral artery territory who had nonepileptic rotational vertigo, nausea, and unsteady gait that gradually resolved within a week. A well-demarcated lesion of the posterior insula (homologous to parieto-insular vestibular cortex in monkeys) was probably the cause. This is supported by a contraversive tilt of perceived vertical and by involvement of the adjacent auditory (Heschl's) cortex. Dipole source analysis of late auditory evoked potentials revealed a decreased amplitude of a dipole source in the right insular cortex, whereas two other dipoles situated in the temporal lobe showed symmetric activity.

Acoustic Stimulation↗
PubMed1995

Horizontal canal benign paroxysmal positioning vertigo: reversible ipsilateral caloric hypoexcitability caused by canalolithiasis?

Bithermal caloric stimulation in a patient with a benign paroxysmal positioning vertigo of the horizontal (lateral) semicircular canal (HC-BPPV) revealed a significant hypoexcitability of the affected ear that was reversible when treated by liberatory maneuvers. Both the positional vertigo and caloric hypoexcitability in HC-BPPV are caused by canalolithiasis, a concept strongly supported by the intensity of the positioning nystagmus being maximal when the patient turned his head around the longitudinal z-axis from the left lateral to right lateral position while recumbent (maximum slow-phase velocity [SPV] 176 deg/sec) and being much lower (maximum SPV 55 deg/sec) when he turned his head to the right lateral position while in a supine position (nose up). The dependence of this difference in nystagmus intensity on the initial head position and direction of rotation indirectly proves that the clot moves freely (to and fro) within the segment of the HC diametrically opposite to the ampulla. The reversibility of ipsilateral caloric hypoexcitability is attributed to the clot's (functional) plugging of the HC, which agrees with studies in squirrel monkeys. These data support the view that physiologic caloric responses consist of a major convective and minor nonconvective component.

Aged↗
PubMed1995

Postural stability differentiates "lower body" from idiopathic parkinsonism.

INTRODUCTION: Patients with an akinetic Parkinson syndrome of the lower extremities and a poor response to L-DOPA have been described as "lower body Parkinsonism" (LBP). These patients are characterized by frequent fallings and poor balance. METHODS: We have studied body sway with static (force platform) and dynamic (Equitest) posturography in 11 LBP patients, 6 of them revealing deep white matter lesions on MRI and 10 patients with advanced Parkinson's disease (PD) and compared performance with 30 age-matched controls. RESULTS: When standing on a fixed support the postural performance of both patient groups lay within the normal range. The balance of LBP patients worsened in the static testing in the conditions "eyes open on foam" (p < 0.05) and "eyes closed on foam" (p < 0.0006, of 11 patients falling), whereas the balance of PD patients deteriorated only with "eyes closed on foam" (p < 0.05). Dynamic posturography confirmed these results in 6 different sensory conditions, clearly distinguishing the more unstable LBP patients from PD patients during "standing, eyes closed, foot support sway referenced" (p < 0.005). CONCLUSION: We conclude, that postural adjustments in LBP patients are more disturbed than those in PD patients and posturography can be an additional tool for the differential diagnosis of Parkinson syndromes with gait disorders.

Aged↗
PubMed1995

[Changes in the perioperative venous hemodynamics and after immobilization of the lower extremity].

In a prospective study we examined 60 patients with lower limb injuries preoperatively, every 2nd day after operation, and at 6 and 12 weeks after trauma with the Doppler and Duplex methods. We distinguished between patients with an above-knee plaster and those with a below-knee plaster after operation. We were able to measure blood flow velocity, transverse width of the deep femoral vein and the volume of flow in this vein. Both legs were measured and compared. The results show a significant reduction of blood flow velocity during immobilization, with a small increase of blood volume passing through the vein. We also saw significant dilatation of the vein by up to 20%. These changes were measured not only on the traumatized leg but also on the normal side. The changes were greater with an above-knee plaster than with the below-knee plaster. The venous haemodynamics had still not returned to normal 6 weeks after trauma in the traumatized limb.

Adolescent↗
PubMed1995

[Infarcts in the brain areas supplied by the posterior cerebral artery. Clinical aspects, pathogenesis and prognosis].

The clinical and neuroradiological features of 127 patients with ischemia of the posterior cerebral artery (PCA) and a positive CT scan (n = 122) or pathological angiography findings (n = 63) were analyzed. Unilateral headache was the most common presenting symptom (50%), making complicated migraine an important differential diagnosis. Clinical findings were visual field deficits (93%), sensory (29%), motor (28%), and neuropsychological deficits (25%). Infarcts, including the thalamus (n = 27), were mostly associated with sensory and slight motor deficits. Our findings suggest that motor deficits in PCA ischemia, particularly if minor and reversible, are likely to be due to ischemia-induced edema in the internal capsule adjacent to an associated thalamic infarct. Based on angiography, stroke etiology was considered embolic in 83/127 (65%), atherothrombotic in 20/126 (16%), and probably migrainous in 4 (3%) patients. In the remaining 20 patients (16%), the etiology was uncertain. Prognosis of PCA infarcts is usually good.

Adolescent↗
PubMed1994

Complete DNA sequence of yeast chromosome II.

In the framework of the EU genome-sequencing programmes, the complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome II (807 188 bp) has been determined. At present, this is the largest eukaryotic chromosome entirely sequenced. A total of 410 open reading frames (ORFs) were identified, covering 72% of the sequence. Similarity searches revealed that 124 ORFs (30%) correspond to genes of known function, 51 ORFs (12.5%) appear to be homologues of genes whose functions are known, 52 others (12.5%) have homologues the functions of which are not well defined and another 33 of the novel putative genes (8%) exhibit a degree of similarity which is insufficient to confidently assign function. Of the genes on chromosome II, 37-45% are thus of unpredicted function. Among the novel putative genes, we found several that are related to genes that perform differentiated functions in multicellular organisms of are involved in malignancy. In addition to a compact arrangement of potential protein coding sequences, the analysis of this chromosome confirmed general chromosome patterns but also revealed particular novel features of chromosomal organization. Alternating regional variations in average base composition correlate with variations in local gene density along chromosome II, as observed in chromosomes XI and III. We propose that functional ARS elements are preferably located in the AT-rich regions that have a spacing of approximately 110 kb. Similarly, the 13 tRNA genes and the three Ty elements of chromosome II are found in AT-rich regions. In chromosome II, the distribution of coding sequences between the two strands is biased, with a ratio of 1.3:1. An interesting aspect regarding the evolution of the eukaryotic genome is the finding that chromosome II has a high degree of internal genetic redundancy, amounting to 16% of the coding capacity.

Base Composition↗