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Biomedical subjects

M Ebel

Publications and source records attributed to M Ebel.

12 recordsLinked to original sources
PubMed2002

Trauma to the pontomesencephalic brainstem-a major clue to the prognosis of severe traumatic brain injury.

The objective of this study was to assess the significance of an injury to the pontomesencephalic brainstem in severe traumatic brain injury [Glasgow coma score (GCS) below 8]. Forty victims of severe traumatic brain injury with and with out compounding pathologies almost equally distributed among both groups were studied. The outcome (mean follow-up, 11.3 months) was assessed by means of the Glasgow outcome score (GOS) and of the Disability rating scale (DRS). Injury of the brainstem was detected by electrophysiological investigation (evoked potentials, brainstem reflexes) and magnetic resonance imaging (MRI) carried out early after trauma. Statistical analysis (Wilcoxon signed rank test for matched pairs) revealed a significantly worse initial GCS (median 5 versus 6), GOS (median 3 versus 4), and DRS score (median 6 versus 2) for the group with brainstem lesions than for the group without such lesions. Moreover, there was a significant accumulation of lesions of the corpus callosum, the basal ganglia, and the (para-)hippocampal area detected by MRI in the brainstem lesion group. In addition, the finding of an abnormal cortical component of the median nerve evoked somatosensory potential was significantly more frequent in the patients with brainstem injury. Traumatic brainstem lesions diagnosed by MRI a nd/or electrophysiological investigation are associated with injury to other 'deeply' situated parts ofthe brain. The finding of a brainstem lesion influences to the outcome of patients after severe traumatic brain injury.

Adolescent↗
PubMed2000

Surgery of intrinsic cerebral neoplasms in eloquent areas under local anesthesia.

28 patients with a mean age of 43.6 years were operated on for a cerebral neoplasm situated in close proximity to an eloquent area (24 speech area, 4 motor cortex) from 1996 to 1999. Preoperatively, all patients had undergone a detailed neuropsychological examination. In 10 patients aphasic disturbances could be detected. All patients underwent preoperative PET studies (methionine and (15)O-labeled water with activation during speech or finger tapping). These were performed and co-registered with MRI data to demonstrate the topographical relationship between motor or language function and the tumor borders. Anesthesia was induced with i.v. administration of propofol (150-250 mg/h). Craniotomy was performed under local infiltration anesthesia. After opening of the dura, sedation was stopped and operation was continued with the patient being alert and co-operative. With close clinical observation during electrical cortex stimulation, a speech arrest could be triggered or avoided. The motor cortex was identified by recording the phase reversal of the contralateral SEP of the median nerve and by direct cortical stimulation. As soon as aphasic or motor disturbances appeared, the tumor removal was continued with the goal of avoiding these specific regions. In 27 patients, preexisting neuropsychological and neurological deficits did not worsen. Only one patient was left postoperatively with a major permanent aphasic deficit that was present preoperatively to a minor degree. The use of local anesthesia in craniotomy for surgery of intrinsic cerebral neoplasms in eloquent areas allows for a continuous and repetitive monitoring of speech and motor function during the removal of even those tumors that were previously considered inoperable.

Adult↗
PubMed2000

[Antiviral therapy of hepatitis C].

Hepatitis C is one of the world's leading infectious diseases. The interferon-ribavirin combination therapy is the new standard for the treatment of hepatitis C in naive and relapse patients. Virological sustained response rates can be more than doubled by the IFN-ribavirin combination therapy compared to IFN-monotherapy and treatment duration can be reduced to six months in many cases. The IFN-ribavirin combination therapy has a high relative benefit in patients with unfavorable predictive parameters like high viral load, HCV genotype-1 infection and compensated liver cirrhosis. Anemia is the most important side effect of the guanosin analogue ribavirin. There are no official therapeutic recommendations for non-responder patients at present. These patients should be treated within controlled clinical trials. Monotherapy with PEG(pegylated)-interferons and combination therapies with PEG-interferons and ribavirin are the most promising future therapeutic options.

Antiviral Agents↗
PubMed1995

Pressor, renal and endocrine effects of L-arginine in essential hypertensives.

The pressor, renal and endocrine effect of the physiological precursor of endothelial derived nitric oxide, L-arginine was compared, with a substrate inactive on nitric oxide, hypertonic D-glucose, in hypertensive patients. Ten mild-moderate essential hypertensives were assigned to either L-arginine (n = 5) or D-glucose (n = 5). Substances were infused over 25 min at equiosmolal rates preceded and followed by saline infusion for 25 min. Blood pressure and heart rate were monitored at 3-min intervals, while hormonal and humoral variables, inulin and paraaminohippurate clearance and electrolyte excretion were measured at the end of each period under conditions of maximal diuresis. L-arginine and D-glucose increased serum osmolality comparably and caused similar haemodilution to that with control saline. During L-arginine infusion, systolic and diastolic blood pressure decreased by 16.6% and 11%, respectively, and recovered in the postinfusion period. Heart rate, plasma renin activity, and plasma noradrenaline did not change significantly. The percent blood pressure decrement induced by L-arginine was significantly greater than that by D-glucose. Glomerular filtration rate was stable and renal plasma flow was increased by both substances. However, natriuresis, kaliuresis and chloruresis were markedly stimulated only by L-arginine, which also promoted the development of systemic acidosis, possibly as a consequence of hydrochloridric acid generated during its metabolism. Circulating insulin, atrial natriuretic peptide, growth hormone and glucagon levels were increased and plasma aldosterone was unchanged during infusion of L-arginine. Insulin was stimulated and the other hormones inhibited during infusion of D-glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Arginine↗
PubMed1995

Quantitative surface analysis by total electron yield.

When the surface of a solid sample is irradiated under vacuum by x-rays an electron emission, owing to photoabsorption, can be measured. As the electrons are detected under neglection of their kinetic energies the total electron yield (TEY) is determined. With a tuneable x-ray monochromator the TEY is measured below and above of one of the absorption edges of a given element. A jumplike increase of the TEY signal, due to the additional photoabsorptions in the corresponding atomic level, can be observed - qualitative analysis. The height of this jump can be correlateted to the concentration - quantitative analysis. It can be shown by a fundamental parameter approach for primary and secondary excitations how to use TEY for a quantitative analysis. The information depth lambda of this new method is approximately 2-400 nm depending on the chemical elements and on the original kinetic energies of Auger and photoelectrons. Thus, TEY is located between photoelectron spectrometry and x-ray fluorescence analysis.

Journal Article↗
PubMed1988

Pharmacokinetics of vigabatrin: implications of creatinine clearance.

The pharmacokinetics of both enantiomers of vigabatrin after a single oral dose in healthy young subjects (mean creatinine clearance 120 ml/min) were compared with kinetics in two groups of elderly subjects, one group aged 60 to 75 years (mean creatinine clearance 86 ml/min) and one group aged 76 to 97 years (mean creatinine clearance 30 ml/min). At a dose of 1500 mg, the group with the eldest subjects and the lowest creatinine clearance values showed mean increases of 3.3-fold in the time to reach the maximum concentration, 2.7-fold in the maximum concentration, and 9.8-fold in the AUC; a twofold prolongation of the t1/2; and reduced urinary excretion of the biologically and pharmacologically active S(+)-enantiomer. Changes in the intermediate group were qualitatively similar but quantitatively less. Parallel observations were made for the inactive R(-)-enantiomer. Most of these changes can be related to decreased renal clearance of vigabatrin. No interference of either enantiomer in the renal clearance of the other was noted. A nonlinear relationship between renal clearance and creatinine clearance for both enantiomers is suggested. Knowledge of the patient's renal function and an appropriate dose adjustment will minimize side effects during vigabatrin therapy, especially in elderly patients.

Administration, Oral↗
PubMed1978

Pseudomembranous colitis associated with ampicillin and erythromycin therapy: report of a case.

Pseudomembranous colitis has been observed increasingly often after therapy with several antibiotics. This report describes the case of a patient in whom pseudomembranous colitis developed in association with ampicillin, an extremely rare complication of this drug, and erythromycin, a drug that has not been previously reported to cause the disease. Clinical and pathologic features, pathogenesis, and management are discussed. Early diagnosis and treatment are extremely important to reduce the significant morbidity and mortality associated with this disorder.

Aged↗
PubMedDate not supplied

[Pressor, renal and endocrine effects of systemic infusion of L-arginine in hypertensive patients].

In this study we compared the pressor, renal and endocrine effects of the physiological precursor of endothelial derived nitric oxide, L-arginine, with D-glucose, a substrate inactive on nitric oxide. Ten subjects with mild to moderate primary hypertension underwent infusion with either L-arginine (5 patients) or D-glucose (5 patients). The substances were infused over 25 min at equiosmolar rates, preceded and followed by a 25-min saline infusion. Blood pressure (BP) and heart rate were monitored at 3-min intervals; hormonal and humoral variables, inulin and para-aminohippurate clearance, and electrolyte excretion were measured at the end of each period at maximum diuresis. L-arginine and D-glucose brought about comparable increases in serum osmolality and similar hemodilution as compared with control saline. During L-arginine infusion, systolic and diastolic BP dropped by 16.6% and 11% respectively and recovered during the post-infusion period. Heart rate, plasma renin activity, and plasma norepinephrine did not change significantly. The percent BP decrease induced by L-arginine was significantly greater than that caused by D-glucose. Glomerular filtration rate remained stable, and renal plasma flow increased with both substances. However, only L-arginine stimulated markedly natriuresis, kaliuresis, and chloruresis. It also seemed to induce systemic acidosis, possibly as a consequence of hydrochloric acid generated during its metabolism. Circulating insulin, atrial natriuretic peptide, growth hormone, and glucagon levels increased, and plasma aldosterone remained unchanged during L-arginine infusion. During D-glucose infusion, insulin was stimulated and the other hormones were inhibited.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗