PubMed Health⌕ Search

Biomedical subjects

R Jahns

Publications and source records attributed to R Jahns.

34 records · Page 2Linked to original sources
PubMed1994

[Analysis of the pressure-surface relation of the left ventricle with automatic echocardiographic contour detection].

UNLABELLED: Echocardiographic automatic border detection is a new on-line technique determinating the interface between blood and myocardial tissue thus having the potential to calculate cyclic changes in left ventricular cavity area in real time. It was the main purpose of the current study to evaluate left ventricular pressure-area relationship after administration of nitrates. In 12 patients with normal left ventricular function pressure-area relation was studied after a Swan-Ganz thermodilution catheter was placed in the wedge position and a high fidelity pig tail catheter was placed in the left ventricle. Left ventricular pressure and cyclic changes of cavity area were simultaneously analysed and displayed together as waveforms on the echo screen using a computer interfaced with the echo machine. All measurements were done before and five minutes after administration of 0.8 mg nitroglycerin. Mean systolic and diastolic blood pressure decreased significantly from 145/12 mmHg to 127/8 mmHg (p < 0.05). Mean systolic area decreased slightly from 10 cm2 to 9 cm2 (n.s.) whereas mean enddiastolic area decreased significantly from 18 cm2 to 15 cm2 (p < 0.05). Accordingly there was a downward and leftward shift of the diastolic pressure-area relationship following administration of nitroglycerin. CONCLUSION: Echocardiographic automated border recognition seems to be a promising new on-line method in the detection of left ventricular cavity area changes underlining its potential usefulness in the evaluation of left ventricular performance.

Adult↗
PubMed1975

Types of neuronal responses in the rat thalamus to peripheral temperature changes.

Recordings were made of spike-trains from 163 neurons of the rostral part of the ventrobasal thalamus complex of the rat while the temperature of the scrotal skin was altered. The following results were obtained: 55 neurons were non-thermosensitive, 7 neurons cold-sensitive and 101 neurons warm-sensitive. In the case of the warm-sensitive cells a definite discrimination was possible: 61.4% of the neurons altered their firing behavior during peripheral cooling, changing from relatively even spike frequency to burst firing. This change could be induced repeatedly by altering the temperature. 38.6% of the neurons, on the other hand, reacted to cooling by slowing down their frequency. By way of statistical methods the firing patterns of the two response-types were analyzed more precisely and the differences in response to temperature stimuli more exactly defined. Likewise, the spatial distribution of the two response-types of warm-sensitive cells exhibited differences; whereas the cells devoid of burst activity occured rather uniformly in the region of the thalamus studied, the cells with bursting activity were confined more to the mediocaudal region. These findings are discussed with regard to the phenomenon of peripheral bursts and to the projection of thermoafferent pathways onto the ventrobasal thalamus complex. The functional interpretation of the various cell reactions and their role in the central processing of thermoafferent signals still remains unexplained and requires comparative studies of peripheral and central parts of the thermoafferent system.

Animals↗
PubMedDate not supplied

Three-dimensional power Doppler sonography in screening for carotid artery disease.

PURPOSE: Color Doppler sonography has gained considerable recognition as a noninvasive method to detect carotid artery disease and to assess the degree of carotid artery stenosis. However, results are highly operator-dependent and cannot be presented as survey images. The purpose of this study was to evaluate real-time 3-dimensional (3D) power Doppler sonography as a method for screening for atherosclerosis in the carotid arteries. METHODS: We prospectively screened 75 patients for carotid artery disease using both conventional color Doppler sonography and 3D power Doppler sonography, and the results from the 2 modalities were compared. A total of 150 common carotid arteries, 150 internal carotid arteries, and 150 external carotid arteries were examined utilizing a 7.5-MHz linear-array transducer combined with tissue harmonic imaging. RESULTS: Color Doppler sonography detected 297 normal or atherosclerotic arteries without stenosis, 57 arteries with mild (1-49%) stenosis, 41 with moderate (50-69%) stenosis, 32 with severe (70-99%) stenosis, and 9 with occlusions. The degree of stenosis determined by color Doppler sonography correlated with that determined by 3D power Doppler sonography (r = 0.982-0.998). Moreover, there was a good correlation between the measurements for both the length of the lesion and its distance from the bulb as determined by the 3D volume surveys and by color Doppler sonography (r = 0.986). The interobserver variability rate was 3.7% +/- 0.5%. Generally, the acquisition and reconstruction of the 3D data took less than 5 minutes. CONCLUSIONS: 3D power Doppler sonography is easy to perform and is an accurate method in screening for atherosclerotic lesions of the carotid arteries. Moreover, it provides excellent 3D volume surveys that may be helpful in the planning of surgical treatment.

Aged↗
PubMedDate not supplied

Exacerbation of Whipple's disease associated with infliximab treatment.

A 34-year-old man with chronic inflammatory joint disease and recurrent fever over 6 years was diagnosed as having Still's disease. Treatment with corticosteroids and azathioprine was ineffective. Therefore, infliximab/ methotrexate was started. The patient subsequently developed a wasting disease with rapid weight loss, erythema nodosum, diarrhoea, progressive lymph node enlargement, and a sigmoido-vesical fistula. Histological analysis of several enlarged lymph nodes, the margins of the fistula, and the small bowel established the diagnosis of Whipple's disease (WD). The presence of Tropheryma whipplei (Tw) DNA in the tissues was confirmed by polymerase chain reaction (PCR). Careful re-evaluation of biopsies taken from the ileum and the liver 2 years earlier, which at that time was not judged to be diagnostic for WD, retrospectively showed subtle histological signs of WD and were positive for Tw DNA. In summary, infliximab treatment seems to increase the risk of exacerbation of WD. WD should be carefully ruled out prior to application of tumour necrosis factor-alpha (TNF-alpha) blockade.

Adult↗
PubMedDate not supplied

Activation and suppression of the trapezius muscle induced by transcranial magnetic stimulation.

Motor evoked potentials (MEPs) and silent periods (SPs) in the trapezius muscle induced by transcranial magnetic stimulation (TMS) were investigated in 15 healthy subjects. Stimuli were applied with a Novametrix Magnetic stimulator using a 14 cm circular coil 4 cm lateral to the vertex on the biauricular line. Surface electrodes were used for simultaneous bilateral electromyographic recordings of the trapezius. TMS invariably induced contralateral MEPs (latency 10.5 +/- 1.3 ms, mean +/- SD), with ipsilateral responses in 53% of the subjects (latency 11.1 +/- 2.5 ms). The mean duration of the SPs was approximately 90 ms on both sides. There were no significant side differences between any of the MEP or SP parameters. To study the influence of subcortical inhibition phenomena TMS induced responses were assessed following electrical mental nerve stimulation with interstimulus intervals (ISI) of 0-100 ms. MEP latencies significantly increased at ISI of 10-100 ms, whereas MEP amplitudes and SPs did not change. These findings may reflect a trigeminal induced exteroceptive suppression of trapezius muscle activity.

Accessory Nerve↗