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Biomedical subjects

J Köster

Publications and source records attributed to J Köster.

14 recordsLinked to original sources
PubMed2005

Telmisartan in patients with mild/moderate hypertension and chronic kidney disease.

AIMS: This study assessed the clinical efficacy and safety of telmisartan, an angiotensin II receptor blocker with a long terminal elimination half-life and almost exclusively excreted in bile, in patients with varying severity of chronic kidney disease (CKD). PATIENTS AND METHODS: Adults with diastolic blood pressure (DBP) 90 - 109 mmHg and stable CKD were enrolled: mild/moderate (creatinine clearance (CrCl) 30 - 74 ml/ min/1.73 m2), severe (CrCl < 30 ml/min/1.73 m2) or requiring maintenance hemodialysis. A two- to four-week single-blind, placebo run-in period preceded once-daily telmisartan 40 mg administration for four weeks. Telmisartan 80 mg was given after four- or eight-week treatment ifDBP > or = 85 mmHg. After 12-week treatment, trough DBP/systolic blood pressure (SBP), DBP and SBP control rates, renal function and tolerability were recorded. RESULTS: Mean changes in DBP/SBP were 10.5/-10.7 mmHg for mild/moderate CKD (n = 27), -11.2/-14.9 mmHg for severe CKD (n = 27) and -15.0/-21.1 mmHg for hemodialysis patients (n = 28). DBP control rates (< 90 mmHg)/SBP responses (< 140 mmHg or > 10 mmHg reduction) occurred in 59.3%/66.7%, 63.0%/70.4% and 71.4%/92.9% of mild/moderate CKD, severe CKD and hemodialysis patients, respectively. Incidences of drug-related adverse events were low, and all were known adverse events of telmisartan and common to other angiotensin II receptor blockers. At the end of treatment, a decrease in 24-h urine creatinine occurred in 5/53 (9.4%) patients. Two patients discontinued treatment prematurely due to the worsening of CKD and one due to aggravated proteinuria. CONCLUSION: Once-daily telmisartan provided effective and well-tolerated treatment of mild/moderate hypertension in CKD patients, with no worsening of renal function.

Administration, Oral↗
PubMed2004

Degradation of 2,4-dichlorophenoxyacetic acid (2,4-d) by a hypersaline microbial mat and related functional changes in the mat community.

Microbial mats possibly possess degradation capacities for haloorganic pollutants because of their wide range of different functional groups of microorganisms combined with extreme diurnal changes in pH, oxygen, and sulfide gradients. In this study, 20 mg/l of the chlorinated herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was applied to a pristine hypersaline cyanobacterial mat from Guerrero Negro, Mexico, under a light regime of 12 h dark/12 h light (600 mumol photons/m(2)s). The loss of 2,4-D was followed by chemical GC analysis; functional changes within the mat were determined with microelectrodes for oxygen, photosynthesis, pH, and sulfide. The depletion of 2,4-D due to photooxidation or sorption processes was checked in control experiments. Within 13 days, the light/dark incubated mats degraded 97% of the herbicide, while in permanent darkness only 35% were degraded. Adsorption of 2,4-D to the mat material, agar, or glass walls was negligible (4.6%), whereas 21% of the herbicide was degraded photochemically. The 2,4-D removal rate in the light/dark incubations was comparable to values reported for soils. The phototrophic community of the mat was permanently inhibited by the 2,4-D addition by 17% on average. The sulfate reduction in the entire mat and the respiration in the photic zone were inhibited more strongly but returned to original levels. Since at the end of the experiment the photosynthetic and respiratory activity of the mats were almost as high as in the beginning and 2,4-D almost completely disappeared, we conclude that the examined mats represent a robust and effective system for the degradation of the herbicide where probably the aerobic heterotrophic population is a major player in the degradation process.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2001

Feasibility of the flash-replenishment concept in renal tissue: which parameters affect the assessment of the contrast replenishment?

The purpose of the study was to evaluate whether power pulse inversion (PPI) and pulse inversion (PI) techniques allow the measurement of indices of microcirculatory flow in real-time at low emission power using contrast microbubbles. PPI and PI imaging were performed in a kidney perfusion model during continuous infusion of Definity (0.12 mL/min). At steady state of tissue enhancement, contrast was destroyed by emission of echo bursts at high emission power (MI = 1.3). Consecutively, contrast replenishment was assessed at low emission power (MI = 0.09) in real-time imaging modes (PPI: 12 Hz; PI: 25 Hz). Regions-of-interest (ROI) of variable sizes were placed in the renal cortex and bigger arteries to compare replenishment of macro- and microcirculation. Nonlinear curve fitting was performed using the mathematical model y=s+A(1-e(-betat)), with A as the parameter describing blood volume and beta as a parameter describing the speed of microbubble contrast replenishment. Replenishment curves could be visually appreciated and quantitatively analyzed in all renal segments. A was significantly higher in bigger arteries compared to renal cortex (p < 0.001). beta was found to be significantly higher in the arteries as compared to the cortex (p < 0.001). The SD of beta diminishes with increasing size of the ROI. The acquisition of replenishment curves following ultrasound (US)-induced destruction of contrast microbubbles is feasible at low power using PPI and PI. Assessment of replenishment kinetics allows the differentiation between macro- and microcirculation. Size and position of the ROI have an important impact on the generation of replenishment curves in both imaging modalities, which has to be taken into account.

Animals↗
PubMed2001

Blood flow assessment by ultrasound-induced destruction of echocontrast agents using harmonic power Doppler imaging: which parameters determine contrast replenishment curves?

OBJECTIVE: To evaluate the feasibility of flow determinations by contrast replenishment using harmonic power Doppler imaging (H-PDI). BACKGROUND: The application of indicator dilution principles on contrast echocardiography is limited by numerous methodical problems. Recently, a new method was introduced that relies on ultrasound-mediated microbubble destruction and evaluation of the contrast replenishment. METHODS: Definity, a perfluorocarbon-derived contrast agent under development, was continuously infused into a steady flow phantom and H-PDI registrations were performed within a silicone tube (d = 8 mm). Replenishment interval between destruction and imaging frame was varied from 0.04-2 seconds. Nonlinear curve fitting was performed using an exponential mathematical model. RESULTS: Strong linear correlation between contrast dose and maximum signal intensity as well as between flow and the slope variable beta of the replenishment curve was found for all settings (r > 0.96). Maximum signal intensity and contrast replenishment rate were found to be a function of emission power and were significantly influenced by depth and focus position. CONCLUSION: The feasibility of flow assessment using replenishment curves obtained by H-PDI was demonstrated. However, in experimental conditions, flow analysis was severely influenced by ultrasound system settings and imaging conditions such as emission power, sound field geometry, and investigation depth. For a clinical use of this promising approach, algorithms that take specific system settings and imaging conditions into account have to be found. Imaging modalities that enable a most homogeneous scan field are best suited for the assessment of contrast replenishment.

Contrast Media↗
PubMed2000

Potential of rheopheresis for the treatment of acute ischemic stroke when initiated between 6 and 12 hours.

Improvement of hemorheology is one of the most important approaches in the treatment of acute ischemic stroke. We investigated the influence of extracorporal rheopheresis (ER) on cerebral blood flow in patients with acute ischemic stroke and evaluated its therapeutic effect. Thirty-three patients (rheopheresis group, 17; control group, 16; mean age 64 +/- 10 years) with acute ischemic stroke were included in our prospective randomized trial. The first treatment was started within 12 h after onset of symptoms, and treatment was repeated 3 times at an interval of 24 h. Hemorheological parameters were measured before and after each session. The cerebral blood flow was analyzed using 99mTc-ECD-SPECT. The functional and neurological outcomes were determined by follow-up investigations after 3 months. The hemorheological parameters were significantly different between the rheopheresis group (18% decrease of plasma viscosity, 55% decrease of red blood cell aggregation) and the control group (no decrease of both parameters). The single photon emission computed tomography (SPECT) analysis showed early reperfusion in 35% of the patients treated with rheopheresis and in 37% of the control group (NS). There were no differences in the neurological outcomes between the 2 groups. Extracorporal rheopheresis is practicable and safe. It rapidly and consistently improved the hemorheological parameters. Although this did not impact on cerebral perfusion or clinical outcome in patients with acute ischemic stroke in this report, we propose that ER deserves to be further evaluated by initiating the first treatment within 6 h post-insult.

Adolescent↗
PubMed2000

Mechanical ventilation in patients with hemispheric ischemic stroke.

OBJECTIVE: Whether stroke patients should be ventilated mechanically is still a contentious issue, because their outcome is very poor. We wanted to investigate how often mechanical ventilation is indicated in patients with hemispheric ischemic stroke as well as the outcome of these patients and the factors by which outcome is influenced. DESIGN: Prospective case series. SETTING: University hospital, neurocritical care unit. SUBJECTS: Subjects were 218 patients who met the following inclusion criteria: age 18-85 yrs, acute hemispheric ischemic infarction, clinical examination, and computed tomography within 6 hrs after the onset of symptoms. INTERVENTIONS: Mechanical ventilation was instituted with one or more of the following conditions: deterioration of consciousness with the inability to protect the airway; PaO2 of <60; P(CO2) of >60 mm Hg; breath rate of >40 breaths/min; and left heart insufficiency with definitive or impending pulmonary edema. MEASUREMENTS AND MAIN RESULTS: Mechanical ventilation was indicated for 52 (24%) of the 218 patients: in 47 (90%) patients because of deterioration of consciousness, and in five (10%) patients because of heart insufficiency and/or pneumonia. In a logistic regression model, the history of hypertension and a size of infarction exceeding two thirds of the middle cerebral artery territory were independent variables for the application of mechanical ventilation. After 3 months, 42 (81%) of these 52 patients had died. The most common cause of death was fatal midbrain herniation caused by complete middle cerebral artery infarction. Patients who survived had a good-to-fair outcome. CONCLUSIONS: New therapeutic strategies (e.g., hemicraniectomy) must be developed to reduce mortality and improve the outcome for this subgroup of ischemic stroke patients. Mechanical ventilation is and will remain a crucial element within such new concepts.

Adolescent↗
PubMed1999

Extracorporeal rheopheresis in the treatment of acute ischemic stroke: A randomized pilot study.

BACKGROUND AND PURPOSE: Extracorporeal rheopheresis is a safe method to optimize hemorheology. Our aim was to determine whether treatment with extracorporeal rheopheresis in patients with acute ischemic hemispheric stroke improves cerebral perfusion as assessed with serial 99mTc-ethyl-cysteinate-dimer single-photon emission CT (99mTc-ECD SPECT). We also investigated how clinical outcome is associated with treatment and imaging results. METHODS: Thirty-three patients (mean age, 64+/-10 years) with acute ischemic hemispheric stroke were included in a prospective, randomized, parallel group pilot study. First treatment with or without extracorporeal rheopheresis took place within 12 hours after the onset of symptoms and was repeated 3 times at intervals of 24 hours. Hemorheological parameters were measured before and after each session. Each patient underwent 99mTc-ECD SPECT immediately before treatment, 6 to 8 hours after treatment, and after 5 days. A semiquantitative SPECT graded scale was used to measure depth and extent of activity deficits and thus to quantify the perfusion deficit. RESULTS: Seventeen patients were actively treated with extracorporeal rheopheresis, and 16 patients did not receive extracorporeal rheopheresis. After 3 months, no differences were found in the functional or neurological outcome. Despite a rapid, sustained decrease of plasma viscosity and erythrocyte aggregation in the rheopheresis group, there was no significant difference in the SPECT graded scale after therapy between the 2 groups. Patients with early reperfusion (decrease in the SPECT graded scale >25% 6 to 8 hours after therapy compared with the baseline examination) experienced a better functional outcome (Modified Rankin Scale) after 3 months compared with patients without reperfusion (P=0.04). CONCLUSIONS: Since quantitative flow mapping and clinical follow-up did not reveal any differences between patients who were treated with extracorporeal rheopheresis and controls, it appears very unlikely that extracorporeal rheopheresis enhances reperfusion after acute cerebral ischemia.

Acute Disease↗
PubMed1998

Mortality of space-occupying ('malignant') middle cerebral artery infarction under conservative intensive care.

OBJECTIVE: To find what the mortality rate of space-occupying ('malignant') middle cerebral artery (MCA) infarction is under maximum conservative intensive care. To establish whether any early indicators of survival exist. DESIGN: Prospective descriptive study. SETTING: Neuro-critical care unit of a university hospital. PATIENTS: Fifty-three patients (mean age 64 +/- 10 years) with 'malignant' MCA infarction. INTERVENTIONS: Maximum conservative intensive care using a standardized protocol (heparin, osmotherapy, tromethamol, mild hyperventilation). The start of therapy was within 12 h after the onset of symptoms. MEASUREMENTS AND RESULTS: The Glasgow Coma Scale (GCS) and Scandinavian Stroke Scale (SSS) were recorded daily. A computed tomography (CT) scan was performed on admission, on day 3 and on day 7. SSS, Barthel Index and Rankin Scale of the surviving patients were recorded after 3 months. On admission, the mean GCS was 13 +/- 3 points and mean SSS 18 +/- 7 points. All patients had to undergo mechanical ventilation (23 +/- 26 h after the onset of symptoms) and were comatose after 28 +/- 30 h. Of 53 patients, 37 (70%) suffered brain death in the intensive care unit (ICU) after an average of 90 +/- 59 h. After 3 months 42/53 (79 %) patients had died. The Barthel Index of the surviving patients was 54 +/- 12 points, the SSS 25 +/- 9 points and the Rankin Scale 3 +/- 1 points. The deceased patients had a significantly higher body temperature on admission than the surviving patients (36.8 degrees C vs 36.3 degrees C). CONCLUSIONS: The mortality of patients with 'malignant' MCA infarction is very high despite maximum conservative intensive care.

Adult↗
PubMed1998

Differentiation between transient ischemic attack and ischemic stroke within the first six hours after onset of symptoms by using 99mTc-ECD-SPECT.

The aim of this study was to define the accuracy of 99mTc-ethyl cysteinate dimer-single photon emission computed tomography (99mTc-ECD-SPECT) in distinguishing transient ischemic attack from completed ischemic stroke at early stages after the onset of symptoms. In a prospective study we examined 82 patients within 6 hours after the onset of symptoms (neurologic deficit caused by middle cerebral artery ischemia) using both 99mTc-ECD-SPECT and computed tomography (CT). The follow-up was based on Scandinavian Stroke Scale (SSS) 24 hours and 5-7 days, as well as on CT 7 days, after the event. SPECT evaluation was performed both visually and using semiquantitative region-of-interest (ROI) analysis. According to visual SPECT analysis, on admission 59 of 82 patients had activity deficits in the symptomatic hemisphere. After 7 days, all these patients had neurologic symptoms (SSS 28 +/- 12 points), caused by a cerebral infarction as evidenced with CT. Twenty-three of 82 patients displayed no early activity deficit despite clinical symptoms. None of these patients had neurologic symptoms after 7 days (indicating transient ischemic attack or prolonged reversible ischemic neurologic deficit). In the semiquantitative SPECT analysis, all patients had abnormal count densities in the respective ROI (activity < 90% compared with the contralateral side). All patients with transient ischemia (n = 23) had count rate densities more than 70% of the respective contralateral ROI, whereas all patients with subsequent infarction (n = 59) had values < 70%. Use of 99mTc-ECD-SPECT allows transient ischemia to be distinguished from ischemic infarction using relative regional activity thresholds within the first 6 hours after onset of symptoms.

Adult↗
PubMed1998

Extracorporeal membrane differential filtration--a new and safe method to optimize hemorheology in acute ischemic stroke.

OBJECTIVE: Can extracorporeal membrane differential filtration be used on patients with acute stroke to optimize their hemorheology without reducing the number of oxygen carriers (erythrocytes) - and is this form of treatment safe? SUBJECTS AND METHODS: In a prospective pilot study, 10 patients (67+/-4 years) suffering severe middle cerebral artery (MCA) stroke were treated with membrane differential filtration, which was first performed within 12 h following the onset of symptoms and repeated three times at intervals of 24 h. Hemorheological parameters were measured before and after each treatment session. RESULTS: Extracorporeal membrane differential filtration treatment immediately led to a significant and sustained drop in all hemorheological parameters (fibrinogen by 54%, alpha2-macroglobulin by 76%, total cholesterol by 65%, LDL by 82%, and HDL by 38%). Plasma viscosity dropped from 1.3 to 1.1 mPa s, erythrocyte aggregation by 57%. By contrast, hematocrit and the erythrocyte count remained constant. Treatment had no side-effects. CONCLUSIONS: Extracorporeal membrane differential filtration is a safe method to optimize hemorheology in patients with acute ischemic stroke.

Aged↗
PubMed1986

Purfication and properties of a specific isoflavone 7-O-glucoside-6''-malonate malonyestrase from roots of chickpea (Cicer arietinum L.).

Protein extracts from roots of chickpea (Cicer arietinum L.) plants contained high esterase activity hydrolyzing malonate hemiesters of isoflavone 7-O-glucosides. Using 5,7-dihydroxy-4'-methoxyisoflavone (biochanin A) 7-O-glucoside-6"-malonate as a substrate, a specific malonylesterase was purified about 700-fold to near homogeneity. The purified enzyme possesses an extremely low enzyme activity with synthetic esterase substrates. Various putative nonspecific esterases, as tested with alpha-naphthylacetate, were removed during enzyme purification. The malonylesterase demonstrated a very high molecular mass in gel chromatography and in sedimentation analyses with sucrose gradients (greater than or equal to 2 X 10(6)). Analytical sodium dodecyl sulfate-polyacrylamide gel electrophoresis pointed to a single subunit of 32,000. The catalyzed reaction showed a pH optimum at 7.5 and a temperature optimum between 30 and 35 degrees C. The apparent Km for biochanin A 7-O-glucoside-6"-malonate was (4.2 +/- 1.2) X 10(-4) M. The malonylesterase was insensitive to the esterase inhibitors eserine and neostigmine (10(-3) M) as well as phenylmethylsulfonyl fluoride, paraoxon, and diisopropylfluorophosphate (10(-4) M). On the other hand enzyme activity was totally inhibited by Hg2+ ions (10(-5) M) and p-hydroxymercuribenzoate (10(-4) M), whereas iodoacetamide (10(-6)-10(-4) M) inhibited only partially. Di- and tricarboxylic acids strongly stimulated enzyme activity at 10(-2) M. These properties indicate that the malonylesterase from chickpea roots greatly differs from other known esterases. The possible biological function of the specific malonylesterase is discussed in relation to isoflavone conjugate metabolism in chickpea.

Carboxylic Acids↗
PubMed1983

Brotizolam as a pre-operative hypnotic.

Efficacy of and tolerance to brotizolam when used as a preoperative hypnotic were studied in two double-blind, randomised parallel group studies. Brotizolam (0.25 and 0.50 mg) was superior to placebo. Efficacy was assessed as good-to-satisfactory in 73.0% of patients with 0.25 mg and in 88.0% with 0.5 mg. A similar assessment was reached in 40.0% of patients with placebo. Brotizolam 0.5 mg was superior to 0.25 mg, and with the higher dose subjective assessments of anxiety were reduced. Efficacy of tolerance to 0.5 mg brotizolam and 2.0 mg flunitrazepam were compared, and both drugs were found to be effective and well tolerated. Brotizolam maintained sleep throughout the night more effectively than flunitrazepam. A dose range of 0.25-0.5 mg brotizolam is recommended as a pre-operative hypnotic.

Adolescent↗
PubMed1978

[Selfinduced gingival mutilations--a diagnostic and therapeutic problem].

A case of factitial gingival traumatism and trichotillomania in a hysteric 28-year-old female patient is reported. During a period of 31 months the patient presented with gingival necrosis which involved the lingual aspects of all four quadrants respectively. A wide range of diagnostical aids failed to enlighten the nature of the lesions until the patient developed an alopecia capitis which was typical for hysteric trichotillomania. The diagnostical and therapeutical aspects of selfmutilation in hysteria are discussed.

Adult↗