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Biomedical subjects

S Baumann

Publications and source records attributed to S Baumann.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Electron-beam tomographic imaging of the coronary arteries: an experimental comparison between monomeric and dimeric x-ray contrast media].

PURPOSE: Comparison of a monomeric and a dimeric radiographic contrast medium in the visualisation of the coronary arteries via electron beam tomography (EBT). MATERIAL AND METHODS: In a total of 6 Göttingen minipigs the heart was examined by EBT (40 sections, ECG-triggering, 1.5 mm section thickness, 100 ms acquisition time) after injection of both iopamidol (monomer, 370 mg l/ml) and iotrolan (dimer, 320 mg l/ml) at a dose of 740 mg l/kg. Injection rate and scan delay were adjusted to heart rate and circulation time. RESULTS: The intravascular increase in density after intravenous injection of iotrolan was significantly higher and longer than after injection of iopamidol (> 300 HE: 28 +/- 4 versus 17 +/- 5 cardiac cycles; p < 0.05). Iotrolan attained a higher score in the visualisation of the coronary arteries in three-dimensional surface reconstructions (p < 0.05). CONCLUSION: The dimeric contrast medium iotrolan proved superior to the monomeric agent iopamidol for visualisation of the coronary arteries via EBT.

Animals↗
PubMed1996

Exogenous gaseous superoxide potentiates the antinociceptive effect of opioid analgesic agents.

The study examined the potentiation of the antinociceptive action of opioid analgesics produced by gaseous superoxide (GS) in the rat hind paw withdrawal test (PWT) and by GS or hydrogen peroxide (HP) in the formalin test. In the PWT, inhalation of GS for 50 minutes before i.p. injection of threshold doses of morphine (0.5 mg/kg) and trimeperidine (1.0 mg/kg) increased the threshold of nociception (TN) by a maximum of 43.0% (p < 0.05) and 113.4% (p < 0.01) respectively. The GS/trimeperidine-dependent increase in TN showed two peaks, the second of which could be suppressed by nialamide. Naloxone abolished the GS/ morphine-dependent increased in the TN. In the formalin test, a significant antinociceptive effect developed after GS inhalation or HP administration (intranasally, 2 x 5 microliters of 2 x 10(-5) mol/l solution in saline) in combination with low doses of Omnopon (0.06-0.75 mg/kg). These results suggest that both GS and HP potentiate the antinociceptive effects of opioid analgesics.

Analgesics, Opioid↗
PubMed1996

[Are psychophysiologic changes in the "public speaking" paradigm an expression of emotional stress?].

Public Speaking is often used to induce anxiety. The emotional stress elicited by the anticipation of delivering a public speech, however, is usually confounded with the mental stress of speech preparation. In order to separate the effects of the emotional from those of the mental stress factor, only half of the subjects were informed about the topic of the speech at the beginning of the anticipation period, whereas the other half were told about the topic at a later time. In a pilot study, the effects of this variation were tested under a condition in which the subjects were told that the speech would be videotaped as an anxiety-provoking and under an emotionally neutral control condition. The main experiment involved an additional condition with a simulated audience designed to intensify the impact of the emotional stress component ("strong anxiety"). Self-reports on present state and cardio-vascular and electrodermal responses were measured in n = 12 subjects in both studies. Knowledge of the speech topic did not affect the subjective anxiety-inducing effects of public speaking. Physiologically arousing effects, however, could be shown without knowledge of the topic only in some variables and only under the "strong anxiety"-provoking condition. In studying public speaking anxiety, confounding with the mental stress of speech preparation should therefore be avoided and a more differentiated interpretation of the physiological effects should be made.

Adult↗
PubMed1995

Human immunodeficiency virus-related microvasculopathy and Kaposi's sarcoma: a case-control study.

Ocular microangiopathic syndrome including retinal and conjunctival abnormalities is frequently found in patients with human immunodeficiency virus type 1 (HIV-1) disease. Kaposi's sarcoma (KS) is the most frequent neoplasia found in patients with HIV-1 disease. We have recently reported a significant association between conjunctival microvasculopathy and KS in 117 patients with HIV-1 disease. The objective of the present study was to determine whether this association is existent when matched patients with and without KS are compared. A total of 22 matched pairs were obtained under consideration of the absolute CD4+ lymphocyte count, Walter Reed (WR) classification, gender, and serum levels of beta-2-microglobulin and neopterin. Conjunctival microangiopathy was determined for each eye by a standardized rating scale ranging from 0 to 5, allowing a reliable and valid quantification of conjunctival blood-flow sludging. The mean value obtained for conjunctival sludge was 1.8 (SEM, 0.4) for patients without KS and 3.2 (SEM, 0.3) for patients with KS, demonstrating a clinically and statistically significant difference between the two groups (Student's t = 3.0; P = 0.003). This difference was higher when patients with a CD4+ lymphocyte count exceeding 200/microliters were regarded. Similar factors or mechanisms may contribute to HIV-related conjunctival microvasculopathy and KS.

Adult↗
PubMed1992

Insulin sensitivity in normotensive subjects during angiotensin converting enzyme inhibition with fosinopril.

The effect of the new ACE-inhibitor, fosinopril, on insulin sensitivity (SI), glucose homoeostasis and lipid profile has been examined in 24 young, healthy, normotensive men. SI, fasting plasma glucose and insulin, serum total triglycerides (Tg) and lipoprotein cholesterol (C) fractions, and ACE activity were assessed after subjects had taken placebo for 1 week and after 3 further weeks either on placebo (12 subjects) or fosinopril 20 mg daily (12 subjects), administered in a double-blind, randomized order. Measurements were made after 3 days on a standard diet (2500 kcal/d, 45% carbohydrates, 40% fat and 15% proteins) and after an overnight fast. Compared with control values at the end of the run-in placebo phase, fosinopril reduced plasma ACE activity (from 106 to 24 nmol.ml-1.min-1), Significantly increased plasma potassium and lowered upright systolic blood pressure. It also improved the k-value of the glucose disappearance rate after glucose load (from -1.70 to -1.88%.min-1) and tended to increase SI slightly although not significantly (from 10.2 to 12.0.10(-4).min-1.microU-1.ml-1). Fasting plasma glucose, insulin, serum total, high-, low-, and very-low density lipoprotein cholesterol fractions and total triglycerides were unchanged following fosinopril and placebo. The findings indicate that in healthy lean humans, ACE inhibition with fosinopril is neutral with regard to lipoprotein and carbohydrate metabolism, and that it may slightly enhance cellular glucose disposal. This calls for further evaluation in individuals at high risk of developing insulin resistance and in patients with impaired insulin sensitivity related to hypertension, obesity, decreased glucose tolerance and diabetes mellitus.

Adult↗
PubMed1990

Localization of auditory response sources using magnetoencephalography and magnetic resonance imaging.

Magnetoencephalography offers the possibility of localizing accurately and noninvasively the source of intracranial currents associated with normal and abnormal brain activity. The purpose of this study was to assess the validity and across-subject reliability of localization of cortical sources responding to ipsilateral and contralateral auditory stimulation. Magnetic evoked fields to both stimulation conditions were measured in eight consecutive normal subjects, and the cortical sources of these fields were estimated on the basis of these measurements. Subsequent projection of the source location coordinates onto magnetic resonance images showed that in all subjects the sources were accurately estimated to fall in the vicinity of the auditory cortex and that two separate sources may account for the response to ipsilateral and contralateral stimulation.

Acoustic Stimulation↗
PubMed1990

Source localization of two evoked magnetic field components using two alternative procedures.

The purpose of this study was to compare the relative efficacy of two methods in assessing the location of the sources of the N100 and P200 components of evoked magnetic fields (EMFs) to transient tone stimuli. EMFs to left ear stimulation, containing both components, were recorded over the right hemisphere of six normal subjects. The magnetic scalp distributions calculated at several adjacent time points, covering the duration of each component's peak, were used to estimate the source parameters of each component. Good estimates of the source of both components were obtained from all magnetic field distributions. The averaged spatial parameters derived from all distributions of each component as well as the parameters derived from the distribution that gave the best source estimate for each component were projected onto magnetic resonance images of subject's head. It was found that the source of each component is located on the superior surface of the temporal lobe and that the source of the P200 component is anterior to the N100 source in all subjects using both procedures.

Acoustic Stimulation↗
PubMed1989

Lack of effects from 2000-Hz magnetic fields on mammary adenocarcinoma and reproductive hormones in rats.

Female rats were implanted with mammary adenocarcinoma tissue and 25 days later exposed to 2,000-Hz magnetic fields 1 h a day for 9 days. Analysis showed that tumor weights and the levels of several reproductive hormones were not significantly different between treated and control animals. Other studies with a similar design have also reported no significant effects from magnetic field exposure. However, vaginal smear data from all animals revealed that handling and restraint stress may have confounded the detection of subtle magnetic field effects.

Adenocarcinoma↗
PubMed1988

[A fatal course of Nelson syndrome].

An unusually therapy-resistant form of Nelson's syndrome developed in a 23-year-old woman two years after treatment of a pituitary-dependent Cushing's syndrome by bilateral adrenalectomy (1977). Removal of a corticotrophic adenoma by a first transsphenoidal pituitary operation (1979) brought only temporary relief. Two years later, regrowth and apoplexy of the pituitary adenoma led to oculomotor paralysis and had to be treated by a second transsphenoidal operation (1981). A second relapse became manifest two years later. Treatment with bromocriptine relieved the headaches but did not diminish the tumor size. A third pituitary operation (1984) became necessary when neurological signs revealed penetration of the cavernous sinus. The tumor was only partly removed by transsphenoidal surgery. Postoperative deterioration of the patient required emergency craniotomy to check a subarachnoidal hemorrhage and for removal of the remaining tumor. The patient died three days later of pneumococcal meningitis which had developed after the third pituitary operation.

Adrenalectomy↗
PubMed1986

[Effects and side effects of transdermal scopolamine for premedication in general anesthesia in elderly patients].

Transdermal scopolamine has already proved an effective premedication to prevent postoperative nausea and vomiting. In a double-blind study, the effects and above all the side effects of TTS-scopolamine (TTS-s) and TTS-placebo (TTS-p) were investigated in elderly patients (greater than 50 years), who are particularly susceptible to adverse drug reactions. The 59 (out of 61) male and female patients who could finally be evaluated had to undergo long (1-6.3 hrs.) surgical or gynaecological interventions in general anaesthesia after premedication with benzodiazepines in the evening and in the morning. The operations were performed under intubation anaesthesia induced by barbiturate (3-5 mg/kg bw) or etomidate (0.2-0.3 mg/kg bw), together with enflurane (0.5-2.5 vol.%) or isoflurane (0.5-1.5 vol.%), N2O/O2 (2:1) and fentanyl (0.05-0.45 mg). Alcuronium or vecuronium were given for relaxation, pyridostigmine/atropine was administered for antagonisation. The patient groups did not differ significantly with regard to age (mean = 65 years vs. 63 years), sex, height, weight, concomitant diseases, method and duration of operation, method and duration of anaesthesia, postoperative antagonisation and analgesia. In patients under TTS-s postoperative nausea was less intensive and of shorter duration. In contrast to 7 patients of the placebo group (p less than 0.05), no case of vomiting could be observed in the TTS-s group. The efficacy of TTS-s was significantly better than that of TTS-p. TTS-s and TTS-p were both tolerated equally well. In both groups, the most frequent side effect was dryness of the mouth, but without any significant differences between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1985

5-year follow-up study of children with low-to-moderate lead absorption: electrophysiological evaluation.

Forty-nine children aged 6 to 12 years were evaluated for residual effects of lead exposure using psychometric, electrophysiological, and medical tests 5 years after initial assessment. The original range of blood lead (PbB) levels was 6-59 (mean = 28) micrograms/dl; the current range was 6-30 (mean = 14) micrograms/dl. A linear relationship between PbB and slow brain wave voltage during sensory conditioning was observed at initial evaluation and at 2-year follow-up. No significant relationship between PbB and slow wave voltage during passive conditioning was found at the 5-year follow-up, although a linear increase in slow wave negativity relative to the current PbB level during active conditioning was suggested by exploratory analyses. Another exploratory analysis revealed a significant linear relationship between the original PbB levels and the latency of waves III and V of the brainstem auditory evoked potential. The latency of both waves increased as a function of original PbB. Increased latency of these waves is suggestive of subclinical pathology of the auditory pathway rostral to the cochlear nucleus, although end-organ impairment cannot be ruled out. No threshold for the effect of Pb on auditory function was apparent.

Brain↗