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Biomedical subjects

G Seidel

Publications and source records attributed to G Seidel.

At least 73 records · Page 4Linked to original sources

Evaluation of the ventricular system in adults by transcranial duplex sonography.

Transcranial duplex color-flow sonography provides visualization of intracranial structures, and measures angle-corrected blood flow velocity in the basal cerebral arteries of adults. In 44 patients with central nervous system disease, the oblique diameters of the third and the middle part of the lateral ventricle were measured by transcranial duplex color-flow sonography using a system with a 2.5-MHz transducer, and compared to computed tomography measurements. The correlation coefficients for the third and lateral ventricle measurements were r = 0.83 (p < 0.0001, N = 38) and 0.73 (p < 0.0001, N = 78), respectively. A second investigation was performed by transcranial duplex to evaluate intraobserver and interobserver reproducibility. The correlation coefficient representing interobserver reproducibility in 27 patients was r = 0.87 (p < 0.0001, N = 47) for the lateral ventricle and r = 0.9 (p < 0.0001, N = 49) for the third ventricle. The intraobserver reproducibility correlation coefficient was r = 0.93 (p < 0.0001, N = 22) for the lateral ventricle in 12 patients. In 49 healthy volunteers the oblique diameters of the lateral and third ventricles were age dependent, measuring 16.7 +/- 2.3 mm and 4.8 +/- 1.9 mm, respectively, in those younger than 59 years, compared to 19.0 +/- 2.9 mm and 7.6 +/- 2.1 mm in those 60 years or older. Therefore, transcranial duplex color-flow sonography measures noninvasively the third and the lateral ventricle in adults.

Adult↗

Phase I: transcranial echo contrast studies in healthy volunteers.

BACKGROUND AND PURPOSE: Transcranial ultrasound diagnostics are particularly hindered by insufficient ultrasound penetration through the temporal bone. The use of ultrasonic contrast media to enhance the Doppler signal is an important step toward the solution of this problem. In the present study we investigated the tolerability and the diagnostic value of a new intravenous transpulmonary ultrasonic contrast medium, BY963. METHODS: In two phase I studies, 8 healthy volunteers received a spherosome suspension containing a phospholipid as the active ingredient. The intravenous injection was performed in three doses (2.5, 5, and 10 mL) at four different injection rates (0.25, 0.5, and 1 mL/s and bolus). The duration and degree of the signal enhancement were measured by two transcranial ultrasonic procedures presently used in clinical practice: transcranial Doppler sonography (TCD) and transcranial color-coded sonography (TCCS). The assessment of tolerability was based on chemical laboratory parameters and hemodynamic data (heart rate, blood pressure, electrocardiogram) and on questionnaires relating to general well-being. RESULTS: BY963 was tolerated without complications. All 38 administrations of the echo contrast medium produced a marked increase in the TCD signal (> 30 dB) in the intracranial basal cerebral arteries. To obtain the optimum time window for diagnostic use, higher doses with slower injection rates are advantageous. The duration of optimal contrasting was 42 to 68 seconds (TCD) and 12 to 132 seconds (TCCS), depending on the method and mode of administration. Bolus injections gave rise to an increased incidence of color artifacts. CONCLUSIONS: BY963 significantly improves intracranial Doppler imaging while being well tolerated. The signal enhancement lasts long enough for TCCS to display all basal cerebral arteries after just one injection.

Adult↗

Potential and limitations of transcranial color-coded sonography in stroke patients.

BACKGROUND AND PURPOSE: Transcranial color-coded duplex sonography (TCCS) enables visualization of the intracranial parenchymal structures and measurement of blood flow velocity in the basal cerebral arteries. The present study aims to evaluate prospectively the clinical usefulness of TCCS in patients with acute stroke. METHODS: Eighty-four consecutive patients with central nervous symptoms suggesting acute stroke were investigated within the first 48 hours after clinical onset. TCCS was performed with a 2.5-MHz sector transducer through the temporal bone window. CT was available in all patients. RESULTS: Forty-eight patients suffered from an infarction or a transient ischemic attack (TIA) in the territory of the middle cerebral artery (MCA). Fifteen of them showed an MCA occlusion, and 12 of the 15 developed recanalization during follow-up. Twelve revealed an increased, decreased, or oscillating flow pattern in the MCA main stem, and 21 patients had no ultrasonic abnormalities. The positive and negative predictive values of a pathological flow pattern in patients with MCA infarctions or TIA were .92 and .48, respectively. Fifteen patients suffered from an intracerebral hematoma, which could be diagnosed by TCCS in 14 cases. The positive and negative predictive values of a pathological parenchymal echo pattern were .88 and .96, respectively. Three patients suffered from an infarction and one from a TIA in the posterior cerebral artery territory. One female patient with an acute deterioration of a hemiparesis showed a glioma. The dropout rate due to an insufficient acoustic temporal bone window was 20% (17/84). CONCLUSIONS: TCCS is a noninvasive bedside method that provides rapid and reliable data regarding stroke subtype and mechanism immediately after onset. Window failure is a serious limitation of this method.

Aged↗

[The solubility and bioequivalence of silymarin preparations].

Seven silymarin products (pharmacies only), two of them with two batches each, were analysed for their ingredients, in particular silibinin (CAS 22888-70-6) and tested in vitro for their liberation of active agents. Founded on the results of these tests three products were checked for bioequivalence. Therefore, a typical phase I 3 fold crossover study was performed showing one product (Legalon) to be qualified by an approx. 2 fold higher silibinin availability compared to the two other preparations.

Adult↗

Effects of human recombinant interleukins on stimulation-evoked noradrenaline overflow from the rat perfused spleen.

Experiments were carried out in the isolated spleen of the rat to study in a lymphoid organ the influence of interleukins (ILs) on noradrenaline release. Spleens were perfused with Tyrode's solution and the overflow of endogenous noradrenaline was determined by HPLC with electrochemical detection. Perivascular electrical stimulation (4 or 10 Hz, 20-28 mA, 2 min) caused an increase in noradrenaline overflow and in perfusion pressure, both of which were markedly reduced by perfusion with Ca(2+)-free solution, abolished by tetrodotoxin, unaffected by hexamethonium, and subject to alpha 2-adrenoceptor- and muscarinic receptor-mediated modulation as shown by the effects of rauwolscine and methacholine. Human recombinant IL-1 beta and IL-2 and mouse recombinant IL-2 10 ng/ml failed to affect the evoked overflow of noradrenaline after an exposure time of 15 min. In contrast, human recombinant IL-1 beta and IL-2 0.1 ng/ml reduced the evoked overflow after exposure for 80 min; the inhibition tended to increase 30 min later despite washout. Murine recombinant IL-2 1.2 ng/ml caused no change after contact with the tissue for 80 min but there was an inhibition 30 min later after washout. Human recombinant IL-6 (0.1 ng/ml) caused no significant change. The inhibitory effect of low concentrations of IL-1 beta and IL-2 supports the idea that locally produced mediators of the immune system may affect neuronal function.

Animals↗

Profound differences in potassium current properties of normal and Rous sarcoma virus-transformed chicken embryo fibroblasts.

The membrane currents of chicken embryo fibroblasts (CEFs) transformed by Rous sarcoma virus (RSV) were compared with the currents of their nontransformed counterparts by using the whole-cell patch-clamp technique. In nontransformed CEFs, the main membrane current is a delayed outward K+ current that is sensitive to tetraethylammonium ion but insensitive to 4-aminopyridine. This K+ current is almost independent of the intracellular Ca2+ concentration and becomes completely inactivated at positive membrane potentials with a time constant of about 10 s at +30 mV. In contrast, transformed CEFs exhibit a noninactivating K+ current that strongly depends on the intracellular Ca2+ concentration. This Ca(2+)-dependent K+ current is blocked by the scorpion toxin charybdotoxin with an IC50 value of 19 nM, whereas the K+ current of normal CEFs is insensitive to charybdotoxin (up to 300 nM). The K+ current properties of transformed CEFs were also found after microinjection of purified, enzymatically active pp60v-src into normal CEFs but not after infection of CEFs with the Rous-associated virus RAV5, which lacks the v-src oncogene. Our results suggest that the oncogene product pp60v-src modulates existing K+ channel proteins, leading to profound electrophysiological and pharmacological alterations of the K+ current properties in RSV-transformed CEFs. Furthermore, our experiments identify for the first time K+ channels as possible substrates of pp60v-src.

Animals↗

The competing discourses of HIV/AIDS in sub-Saharan Africa: discourses of rights and empowerment vs discourses of control and exclusion.

The competing discourses of HIV/AIDS circulating in sub-Saharan Africa are identified. These are medical, medico-moral, developmental (distinguishing between 'women in development' and gender and development perspectives), legal, ethical, and the rights discourse of groups living with HIV/AIDS and of African pressure groups. The analytical framework is that of discourse analysis as exemplified by Michel Foucault. The medical and medico-moral are identified as dominant. They shape the perceptions of the pandemic, our responses to it, and to those living with HIV/AIDS. However, dissident activist voices are fracturing the dominant frameworks, and are mobilising a struggle for meaning around definitions of gender, rights, and development.

Acquired Immunodeficiency Syndrome↗

Transcranial color-coded duplex sonography of intracerebral hematomas in adults.

BACKGROUND AND PURPOSE: It is well established from pediatric experience and animal experiments that intracerebral blood can be demonstrated by B-mode real-time duplex scanning. This has recently become feasible in adults as well. The present study investigated the changes in the sonographic appearance of intracerebral hematomas over the course of time. METHODS: Starting in May 1991, 23 consecutive patients with intracerebral hematoma confirmed by computed tomography (21 spontaneous and 2 traumatic hematomas) were investigated within 1 year. They were monitored by repeated ultrasound scanning via the transtemporal approach. The sonographic appearance of the hematomas on B-mode scans and the angle-corrected blood flow velocity in the basal cerebral arteries were assessed. RESULTS: There was unequivocal localization of the hematoma in 18 patients (78%). In 3 cases (13%), an adequate acoustic window could not be found. One small intracerebral hemorrhage was overlooked, and one extensive hemorrhage in the basal ganglia was misdiagnosed as a lobar hematoma. There was an alteration of the appearance of the hematoma with time. This was divided into three sonographic stages (initial stage, days 1 to 5; intermediate stage, days 6 to 10; and capsular stage, from day 10). In 14 of the 20 patients with an appropriate acoustic bony echo window, the blood flow velocity in the middle cerebral artery could be measured; in 1 of these patients, the signs of increasing intracranial pressure were apparent from Doppler frequency spectrum. In 5 patients, the intracerebral hematoma could be imaged but not the ipsilateral middle cerebral artery. One female patient showed cerebral circulatory arrest at the time of examination, which took place within 24 hours after the onset of clinical symptoms. CONCLUSIONS: Most intracerebral hematomas in adults can be imaged in B-mode. Their sonographic appearance changes over the course of the disease. The advantages of this noninvasive method are its easy bedside operation and its suitability for follow-up; it is also less stressful than other imaging procedures. It yields a combination of structural and functional diagnostic information. In approximately 13% of the cases, the investigation was not feasible because of inadequate ultrasonic penetration of the intact skull.

Adult↗

Imaging of the intracranial vertebrobasilar system using color-coded ultrasound.

BACKGROUND: Anatomic variety and difficult accessibility of the vertebrobasilar arteries pose considerable problems to conventional ultrasound. We evaluated the diagnostic potential of transcranial color-coded sonography in the distal part of this system. METHODS: We insonated the intracranial section of the vertebrobasilar arteries through the foramen magnum window in 24 healthy individuals using a Doppler color flow imaging system in connection with a 2.5-MHz sector transducer. Magnetic resonance images in special inclination planes were performed and compared with the color-coded duplex images in five cases. RESULTS: The B-mode image of the craniocervical junction and the intracranial parenchymal structures in addition to the color-coded blood flow allowed an unambiguous identification of the vertebrobasilar arteries (vertebral artery, 96%; basilar artery, 79%; and posterior inferior cerebellar artery, 50%). Blood flow velocities were measured considering the insonation angles: vertebral arteries, 50/24 cm/sec (30 degrees); basilar artery, 59/28 cm/sec (4 degrees); and posterior inferior cerebellar artery, 56/30 cm/sec (20 degrees) [peak systolic/end diastolic blood flow velocity (mean angle correction)]. CONCLUSIONS: Transcranial color-coded sonography enables accurate identification and differentiation of the intracranial vertebrobasilar arteries and improves accuracy of Doppler measurements. It may prove useful for evaluation of tortuosity and for hemodynamic studies in this vascular territory.

Adolescent↗

Nursing home autopsies. Survey of physician attitudes and practice patterns.

Autopsy rates remain disturbingly low in nursing homes despite the fact that 1 of 5 deaths occurs in this setting. To determine the autopsy rate for nursing homes, we analyzed all deaths occurring in New York State nursing homes from 1980 to 1984. Of 58,985 nursing home deaths, autopsies were performed in only 499 cases (0.8%). In comparison to the general nursing home population, autopsied residents were more likely to be male and never married and less likely to be widowed. Of 110 practicing nursing home physicians surveyed, 19% believed autopsies had little if any value in the nursing home population, whereas 71% saw autopsy as a valuable tool but rarely requested one. Fewer than 1 in 10 physicians routinely discussed autopsies with patients and/or families before death. Perceived obstacles included the emotional lability of patients and families and a lack of financial reimbursement. Concerns over religious objections, funeral delays, and unnecessary mutilation were cited by fewer than one third of respondents. Facilitation of consent, physician education, and cost sharing may all contribute to enhanced rates of autopsies in the future.

Aged↗

[Endometriosis externa thoracalis].

The incidence of endometriosis is between eight and 15 percent among sexually mature women, with peaks being in the third and fourth decades of age. External thoracic endometriosis is associated with implantation of endometrial tissue into lung, pleura, bronchial system, and diaphragm. Major indicators symptoms of thoracal endometriosis include haemoptysis, thorax pain, recurrent spontaneous pneumothorax, and haemorrhagic pleural effusion, with all these manifestations being temporally coordinated with menstruation. Bronchoscopy and radiography are used for diagnosis, while surgery, hormonal treatment, and radiotherapy are used for therapeutic action. One patient with systemic endometriosis is reported in greater detail in this paper.

Adult↗

[Generalized endometriosis].

Authors report on a case of generalized endometriosis. A 29 years old patient suffered from a primary amenorrhea by reason of an aplastic uterine cervix and an incomplete vaginal aplasia. Endometriosis has been ascertainable histologically in the uterus, in the left tube, near the gall bladder and in the pleura.

Adult↗

Investigation of possible interaction between pinaverium bromide and digoxin.

A single-blind study was carried out in 25 patients, who were receiving maintenance therapy for congestive heart failure with digoxin, to investigate the effect on steady-state plasma digoxin levels of concomitant administration of the spasmolytic, pinaverium bromide (50 mg 3-times daily). Patients received pinaverium bromide for 12 days followed by placebo for a further 7 days. Assessment of the results in 21 patients showed no evidence of any statistically significant variations in plasma digoxin levels during either treatment period or in the clinical observations which might indicate drug interaction.

Adult↗

Penetration of cefotaxime into the pancreas.

After intravenous injection of cefotaxime, higher pancreatic concentrations of the antibiotic were found in rats with experimental pancreatitis than in control animals. Also in human pancreatic pseudocysts, high and persistent concentrations of cefotaxime were found following intravenous injection. The results justify the use of cefotaxime in acute pancreatitis, whenever an antibiotic is indicated.

Animals↗

[Selenium compounds and carcinogenesis].

Starting with a brief outline of the general toxic effects of selenium compounds, their biological importance for the organism as a trace element and with an analysis of the different hypotheses on the action mechanism of selenium and selenium compounds, a survey is provided in which way selenium compounds may influence malignant transformation and related processes in vivo and in vitro. Furthermore, observations are viewed on the effects of selenium compounds on spontaneously developing, chemically or virally induced tumors. Based on the data available so far it cannot, at present, be assessed whether selenium and its compounds can be used in the future for chemoprevention of cancer.

Animals↗