PubMed Health⌕ Search

Biomedical subjects

P Karen

Publications and source records attributed to P Karen.

At least 19 recordsLinked to original sources
PubMed2004

Confocal stereology and image analysis: methods for estimating geometrical characteristics of cells and tissues from three-dimensional confocal images.

A short review of confocal stereology and three-dimensional image analysis is presented, pointing out the achievements accomplished in this field by the Department of Biomathematics (Institute of Physiology, Prague). One of the methods of confocal stereology, the fakir method for surface area estimation, developed by this laboratory, is described. Methods for automatic measurement of geometrical characteristics of microscopical structures, based on 3-D image processing or surface triangulation, are discussed and compared with interactive stereological methods. Three-dimensional reconstruction programs and software implementation of stereological and digital methods as well as their practical applications are presented. The future trends are discussed.

Animals↗
PubMed2000

Low to high spin-state transition induced by charge ordering in antiferromagnetic YBaCo2O5

The oxygen-deficient double perovskite YBaCo2O5, containing corner-linked CoO5 square pyramids as principal building units, undergoes a paramagnetic to antiferromagnetic spin ordering at 330 K. This is accompanied by a tetragonal to orthorhombic distortion. Below 220 K orbital ordering and long-range Co(2+)/Co(3+) charge ordering occur as well as a change in the Co2+ spin state from low to high spin. This transition is shown to be very sensitive to the oxygen content of the sample. To our knowledge this is the first observation of a spin-state transition induced by long-range orbital and charge ordering.

Journal Article↗
PubMed2000

STESYS2: extended STESYS software for MS Windows.

The STESYS2 software is a new version of the IBM PC software supporting interactive stereological measurements. In comparison with the previous STESYS, it is enhanced by a number of useful options, e.g. on-line image input via a TV camera coupled with a microscope operating under MS Windows OS. The main advantage, when compared with other such software packages, is the design of the STESYS2 as a module of the freeware image processing system Image Tool which provides a user-friendly environment including a number of image processing and preprocessing routines. Capabilities of the STESYS2 are illustrated by a practical example: estimation of the surface area of capillaries in the terminal villi of human placenta by the Sandau spatial grid method.

Capillaries↗
PubMed1998

STESYS software for computer-assisted stereology.

A software system STESYS for interactive and flexible generation of stereological test systems is described. STESYS enables to implement many of the recent unbiased stereological methods applied to biomedical research and clinical diagnosis by using a simple personal computer. Advantages of the STESYS software are illustrated by several examples of stereological measurements for estimating the number, total and mean cross-sectional area, volume and surface area.

Axons↗
PubMed1995

Regulation of amiloride-sensitive Na+ transport in immature rat distal colon by aldosterone.

The effects of dietary changes and plasma aldosterone levels on channel-mediated electrogenic amiloride-sensitive Na+ transport were examined in the distal colon of immature and adult rats. The decrease of the short-circuit current after amiloride addition (ISCamil) was used as a measure of electrogenic Na+ absorption. Plasma aldosterone levels were six to eight times higher between d 15 and 30 than in younger suckling or prepubertal rats. In adult rats, the plasma aldosterone was approximately 30 times lower than in young animals kept on the same standard diet. ISCamil followed the developmental profile of plasma aldosterone. ISCamil increased between d 10 and 20, reached a plateau between d 20 and 25, then decreased and entirely disappeared after d 30. ISCamil was zero in adult distal colon but was induced if dietary Na+ intake decreased below 100 mumol Na+/(100 g body wt.d) and plasma aldosterone increased above 200-300 pg/mL. Adrenalectomy, or high Na+ intake, inhibited ISCamil and significantly depressed plasma aldosterone in 20- and 25-d-old rats. Premature weaning decreased ISCamil without appreciable changes in plasma aldosterone in 18- and 20-d-old rats, prolonged suckling inhibited ISCamil and caused a significant depression of plasma aldosterone. We conclude from these results that the postnatal changes of distal colonic Na+ transport are regulated predominantly by circulating aldosterone and dietary Na+ intake.

Adrenalectomy↗
PubMed1995

Computer graphics editor GSE and some of its applications in morphology.

A simple, vector-based graphics editor, designed for experimental data presentation, schematics, large structured chemical formulae etc. in a modest IBM PC, MS DOS environment is described. Its applications in semi-automatic image analysis, especially in the implementation of design-based stereological methods for estimating global geometrical characteristics of studied samples and in 3D volume reconstruction from serial sections are discussed.

Computer Graphics↗
PubMed1993

Predicting therapeutic results with levoprotiline and maprotiline in major depression: the role of the outcome criteria.

We describe a double-blind study involving 58 in-patients with major depression (DSM-III). After one week on placebo, the patients were randomly assigned to either levoprotiline or maprotiline treatment for three weeks. In the next three weeks, responders were maintained on the same medication and non-responders were shifted to treatment with the complementary drug. After the initial three weeks' treatment, 31% of levoprotiline patients and 58% of maprotiline patients had responded. Both in the initial three-week period and after shifting non-responders to the complementary drug, there were significant differences in favour of maprotiline. The comparison of properties of different outcome criteria in prediction analyses shows that the final score gives the best agreement with global evaluation; using the delta score (final minus baseline) or ratio score (final/baseline) as the outcome criterion may yield paradoxical results.

Adult↗
PubMed1992

Treatment of extrapyramidal side effects with terguride.

Terguride, a partial dopamine agonist, was administered in a 4-week open clinical trial to 17 schizophrenic patients suffering from extrapyramidal side effects of neuroleptic treatment. The neuroleptic dosage was kept constant. The mean final daily dose of terguride reached 3.4 mg (SD = 2.0). Fourteen patients completed the trial. Total scores on the Rating Scale for Extrapyramidal Side Effects and the Brief Psychiatric Rating Scale showed a significant improvement of 69% and 40%, respectively. There was also a significant improvement in all BPRS factor scores.

Administration, Oral↗
PubMed1992

[Results of a clinical trial of levoprotiline].

The authors submit results of a double blind clinical trial of levoprotiline controlled by maprotiline. In the multicentre study (which is processed and interpreted in stages) participated after written informed consent 58 patients with the diagnosis of a major depressive disorder. During the first three weeks the results of levoprotiline and maprotiline (from 26 patients each) were processed. The trial lasted 42 days. The psychopathology of the patients was evaluated by independent blind raters by means of Montgomery and Asberg's scale (MADRS), Hamilton's scale for depression (HRDS) and general clinical impression (CGI). In all patients also the pharmacological and EEG response was assessed. In comparison to maprotiline, levoprotiline was clinically ineffective. Its plasma levels (40 ng/ml) were one third to one half of the values obtained with maprotiline in the same daily dosage (150 mg). Although levoprotiline has an EEG profile typical for classical thymoleptics, its clinical antidepressive action is negligible.

Adult↗