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Biomedical subjects

M Stemmler

Publications and source records attributed to M Stemmler.

13 recordsLinked to original sources

The Alzheimer's disease activities of daily living international scale (ADL-IS).

BACKGROUND: Activities of daily living (ADL) deficits are integral components of dementia disorders, and ADL measures are among the most robust markers of the course of Alzheimer's disease (AD). Despite this acknowledged importance, no clearly useful ADL instrument for cross-cultural application in pharmacologic trials in the early stages of AD had been available. METHOD: An international effort was launched to develop an ADL scale for pharmacologic trials in early AD. Steps taken from 1990 to the present included: (1) international scientific working group meetings and reviews, (2) reviews of existing measures, (3) collating of existent, nonredundant items, (4) querying experts for new items, (5) interviews with informants and subjects in the USA, France, and Germany, toward the identification of potential new items, (6) identification of an item pool based upon these procedures, (7) creation of a trial instrument, (8) piloting of this instrument, and (9) refinement of the scale based upon statistical analysis of the pilot data. Final item selection was based upon: (1) relevance for > or = 80% of subjects in severity-stratified USA and German samples; (2) absence of gender and national biases; (3) significant (p <.05) discrimination between (a) normal versus mildly impaired and (b) mildly impaired versus moderately to moderately severely impaired subjects; and (4) Global Deterioration Scale (GDS) scores accounting for > or = 12% of variance in the item after controlling for age and gender. RESULTS: An ADL scale consisting of 40 items that correlate with the global and cognitive progress of AD is developed for international usage in pharmacologic trials in incipient, mild, moderate, and moderately severe AD. The scale contains 40 items falling within 13 ADL categories. The 40-item scale is shown to have .81 correlation with GDS staging, .81 with mental status assessment (Mini-Mental State Examination), and .81 with a psychometric test (the SKT) (p values < .001). CONCLUSION: This scale can be used to measure therapeutic response in AD.

Activities of Daily Living↗

Comparison of closely related orthopoxvirus isolates by random amplified polymorphic DNA and restriction fragment length polymorphism analysis.

The reliability and reproducibility of random amplified polymorphic DNA analysis (RAPD) was compared with restriction fragment length polymorphism (RFLP) by analysing three virus strains isolated from zoo animals in Berlin and three isolates which were cultivated from pets from Northern Germany. The RAPD technique was evaluated as a reliable tool with good reproducibility of the patterns for each virus strain investigated. Problems of interpretation due to inconsistent intensity of bands in different polymerase chain reaction runs may arise for less experienced personnel. The RAPD analysis can be performed within one working day and needs less DNA compared with RFLP so costs will be reduced. The obvious advantage of RFLP is that the pattern can be traced to the recognition site of the restriction enzyme whereas the RAPD primer sequence is not present in the orthopoxvirus genome at all. To the authors knowledge, the RAPD technique has never been applied in DNA viruses before and they conclude that this technique is a useful tool for the discrimination of closely related cowpoxviruses.

Animals↗

How voltage-dependent conductances can adapt to maximize the information encoded by neuronal firing rate.

Information from the senses must be compressed into the limited range of responses that spiking neurons can generate. For optimal compression, the neuron's response should match the statistics of stimuli encountered in nature. Given a maximum firing rate, a nerve cell should learn to use each available firing rate equally often. Given a set mean firing rate, it should self-organize to respond with high firing rates only to comparatively rare events. Here we derive an unsupervised learning rule that continuously adapts membrane conductances of a Hodgkin-Huxley model neuron to optimize the representation of sensory information in the firing rate. Maximizing information transfer between the stimulus and the cell's firing rate can be interpreted as a non-Hebbian developmental mechanism.

Electric Conductivity↗

Intravenous titration with morphine for severe cancer pain: report of 28 cases.

BACKGROUND: In a multicenter study, 28 patients with cancer pain and insufficient pain relief with analgesic treatment according to step II of the guidelines of the World Health Organization (WHO) were switched to oral slow-release morphine. METHODS: Patients received intravenous morphine through a patient-controlled pump (PCA) for the first 24 hours (bolus = 1 mg, lockout interval = 5 minutes, maximum dose = 12 mg/hour). From day 2 patients were treated with oral slow-release morphine. Daily doses were calculated from the requirements of the day before. Breakthrough pain was treated with PCA until stable doses were reached (<2 boluses/day) and then with oral immediate-release morphine solution. Pain intensity was reported in a diary four times a day, in addition to mood, activity, and quality of sleep once daily. RESULTS: Mean duration until adequate pain relief reported (<30 on a 101-step numerical scale; NRS) was 5 hours (range = 80-620 minutes). Mean pain intensity was reduced from 67 NRS to 22 NRS. Mean doses of oral morphine were 133 mg/day initially and then 154 mg/day on day 14. Serious adverse events such as respiratory depression were not observed. Two patients terminated the study due to progressive symptoms of gastrointestinal obstruction. Seventy-five percent of the patients evaluated the effectiveness of the analgesic regime as good. CONCLUSIONS: Dose finding with intravenous PCA may be appropriate for a small minority of patients with severe pain. Higher treatment costs and the risk of complications are drawbacks of this method compared with conventional oral titration.

Administration, Oral↗

Duration of lithium treatment and brain lithium concentration in patients with unipolar and schizoaffective disorder--a study with magnetic resonance spectroscopy.

Twenty psychiatric patients on lithium medication were examined with 7-Li-magnetic resonance spectroscopy of the brain. Patients on long-term lithium treatment (> 6 months) were compared with a short-term group who had been taking lithium for between 4 and 8 weeks. Patients met DSM-III-R criteria for either recurrent unipolar depressive disorder (DSM-III-R 296.3x) or schizoaffective disorder, depressive type (DSM-III-R 295.70). The brain:serum lithium ratio was 0.76 +/- 0.26; there was no significant difference between short-term and long-term treatment. In the group of long-term treatment patients there was a positive correlation between lithium dose per day and brain lithium concentration (R = .72, p < .01), and between lithium plasma concentration and brain lithium concentration (R = .65, p < .05). In the short-term group, however, there was no significant correlation for these parameters. No differences between unipolar and schizoaffective disorder were found.

Adult↗

Pharmacokinetics of intraarterial mitomycin C in the chemoembolisation treatment of liver metastases.

1. The pharmacokinetics of mitomycin C (MMC) were investigated in 12 colorectal cancer patients with liver metastases undergoing chemoembolisation. Hepatic artery branches were embolized using polyvinylalcohol microspheres (150-250 microns) before applying 20 mg MMC in 4-8 min. 2. Serum MMC concentrations were determined from peripheral venous blood samples by reverse-phase HPLC using ultraviolet detection. Pharmacokinetic parameters were computed assuming an open two-compartment model. 3. Pharmacokinetic parameters were similar to values given in the literature for intravenous (IV) or intraarterial (IA) bolus MMC injections (Tmax = 7.0 min following the beginning of MMC infusion, Vss = 0.57 1/kg, C1 = 8.9 ml/min.kg, T1/2 alpha = 8.3 min, T1/2 beta = 58.6 min). 4. The area under the serum concentration-time-curve (AUC), standardized by the MMC amount injected, was similar to values reported in the literature for IV or IA bolus injections. There is no evidence for reduced systemic MMC exposure following the embolization procedure used.

Antibiotics, Antineoplastic↗

Lateral interactions in primary visual cortex: a model bridging physiology and psychophysics.

Recent physiological studies show that the spatial context of visual stimuli enhances the response of cells in primary visual cortex to weak stimuli and suppresses the response to strong stimuli. A model of orientation-tuned neurons was constructed to explore the role of lateral cortical connections in this dual effect. The differential effect of excitatory and inhibitory current and noise conveyed by the lateral connections explains the physiological results as well as the psychophysics of pop-out and contour completion. Exploiting the model's property of stochastic resonance, the visual context changes the model's intrinsic input variability to enhance the detection of weak signals.

Animals↗

Mitomycin-C concentration in human ocular aqueous humor after topical administration during trabeculectomy.

UNLABELLED: The concentration of the antitumor antibiotic mitomycin (CAS 50-07-7, mitomycin C, MMC), used in ophthalmic surgery for its antiproliferative effects, was measured in the aqueous humor of 7 glaucoma patients undergoing trabeculectomy. Sponges soaked with MMC-solution (100 microliters of MMC-solution 0.2 mg/ml: 20 micrograms) were applied intraoperatively on the scleral flap for 5 min. 100 to 200 microliters of aqueous humor were drawn with a needle 10 min following the end of topical MMC-treatment. Samples were assayed for MMC using a reverse-phase HPLC-system with ultraviolet detection (C18-column, elution: phosphate buffer (0.01 mol/l, pH: 6.5): methanol, v:v = 70:30, 365 nm). Swabs were extracted in phosphate-buffer (0.1 mol/l, pH: 7.0) before HPLC-analysis. External calibration was used for MMC quantitation. Quantitation limit was 10 ng/ml. In all aqueous humor samples MMC-concentration was below 10 ng/ml. MMC in the swabs amounted to 37% of the MMC amount applied. CONCLUSION: After intraoperative topical application, the MMC concentration in the aqueous humor of patients is very low. The substantial loss of MMC from the swabs used for the topical MMC-treatment suggests 1. rapid systemic absorption of MMC and/or 2. a loss through irrigation of the operative field following topical MMC-application.

Administration, Topical↗

Depression in adolescence.

Adolescence is an important developmental period for understanding the nature, course, and treatment of depression. Recent research concerned with depressive mood, syndromes, and disorders during adolescence is reviewed, including investigations of the prevalence, course, risk factors, and prevention and treatment programs for each of these three levels of depressive phenomena in adolescence. A broad biopsychosocial perspective on adolescent depression is recommended, and possible directions for future integrative research are proposed. Based on current research and knowledge, implications for research, program, and national policy are considered.

Adolescent↗

[Configuration frequency analysis: Kieser's test against Victor's type and syndrome].

Tests against types and anti-types as performed in Victor's Configural Frequency Analysis (CFA) have shown to be non-conservative. The conservative test by Kieser is introduced. It is applied to data describing a sample that performs below average in language tests. For data including small expected cell frequencies the Harms-Ihm adjustment is recommended. It leads to valid chi-squared testing even if expectancies are small. The problem of identifying more than two types or syndromes in exploratory CFA is discussed.

Analysis of Variance↗