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M Kraemer

Publications and source records attributed to M Kraemer.

At least 73 records · Page 4Linked to original sources
PubMed1995

Lymphocytic infiltration and expression of intercellular adhesion molecule-1 in photochemically induced ischemia of the rat cortex.

The contribution of the immune system to the pathogenesis of ischemic lesions is still uncertain. We have analyzed leukocyte infiltration in photochemically induced focal ischemia of the rat parietal cortex by immunocytochemistry. Between 1 and 2 days after photothrombosis, CD5+ T cells adhered to subpial and cortical vessels and infiltrated the ischemic lesion prior to macrophages. By day 3 numerous T cells and some macrophages, whose number increased further between day 3 and day 7, had infiltrated the border zone around the lesion sparing the center. In addition, CD5-/CD8+ lymphocytes that probably represent natural killer cells were found. Intercellular adhesion molecule-1 (ICAM-1) was expressed on endothelial cells on days 1 and 2 and in the border zone on infiltrating leukocytes from day 3 to day 7. Starting on day 7, macrophages infiltrated the core of the lesion to remove debris. When the entire lesion was covered by macrophages at day 14, the number of T cells had decreased and ICAM-1 immunoreactivity was no longer found in or around the infarct. In conclusion, our study shows that ischemic lesions can lead to a local immune reaction in the CNS. Thus, blocking of lymphocyte-derived cytokines or cell adhesion molecules may provide a new approach to confining the sequelae of stroke.

Animals↗
PubMed1995

Plasticity and neurotransmitter receptor changes in Alzheimer's disease and experimental cortical infarcts.

According to recently published data, the propagation of the typical neurofibrillary changes in Alzheimer's disease follows gradually and systematically the main pathways of fiber connections between different cortical areas. The functional deficits show a parallel development. Memory deficits as the first symptom of Alzheimer's disease can be explained by the initial lesion of the entorhinal-hippocampal connection. The next symptom is the impairment of emotional behaviour, which is caused by lesions in the hippocampus and the other parts of the limbic cortex. The following gnostic and praxic alterations can be explained by lesions in the association areas of the neocortex. Finally also motor disturbances become apparent, caused by lesions in the motor cortex. The tissue alterations in Alzheimer's disease represent a systemically spreading lesion in the cortex based on the destruction of synapses and finally of whole neurons, and on the impairment of normal neurotransmission. Since neurotransmission depends on transmitters and their receptors, the densities of transmitter receptors in the hippocampus, parietal association and premotor cortices in Alzheimer's disease were measured with quantitative receptor autoradiography. The degree of receptor changes in these regions decreases with the direction of the propagation of neurofibrillary changes from the hippocampus to the premotor cortex. With the exception of the GABAA receptor, the receptors in the hippocampus are reduced by approximately 70%. The reduction in the parietal association cortex amounts to only 30%. An upregulation of muscarinic M1 receptors was seen in the premotor cortex. The latter result is surprising in the context of a lesion model, but is in agreement with earlier immunohistochemical data about muscarinic receptors in the frontal cortex of Alzheimer patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Alzheimer Disease↗
PubMed1994

Monitoring tricyclic antidepressant concentrations in serum by fluorescence polarization immunoassay compared with gas chromatography and HPLC.

The fluorescence polarization immunoassay (FPIA) developed by Abbott to diagnose intoxication with tricyclic antidepressants was adapted for therapeutic drug monitoring and validated with chromatograpic methods to investigate its potential for this use. We compared serum concentrations of tricyclic antidepressants in vivo and in vitro obtained by FPIA with those by gas chromatography and HPLC. For amitriptyline, imipramine, clomipramine, and doxepin, the detection limit of the FPIA was 72, 71, 64, and 72 nmol/L (approximately 20 micrograms/L), respectively; that by gas chromatography was 18, 18, and 16 nmol/L (approximately 5 micrograms/L) for amitriptyline, imipramine and clomipramine, respectively; with HPLC the lower limit of detection for doxepin was 36 nmol/L (10 micrograms/L). The intra- and interassay CVs ranged from 3% to 6%. In patients being treated with amitriptyline, imipramine, clomipramine, and doxepin, at steady-state the correlation coefficients between FPIA and GC/HPLC results for split samples were 0.95, 0.92, 0.90 and 0.70, respectively. However, the slopes were close to unity only for amitriptyline and doxepin, being 0.6 for imipramine and 1.9 for clomipramine.

Antidepressive Agents, Tricyclic↗
PubMed1993

Electrophysiological changes in the surrounding brain tissue of photochemically induced cortical infarcts in the rat.

Small infarctions in the parietal cortex of Wistar rats were produced photochemically using the Rose Bengal technique. The infarctions evoked reproducible cortical lesions of about 2 mm diameter. In the surrounding brain tissue changes in electrophysiological responses occurred. Whereas in control animals a paired-pulse inhibition could be evoked all over the neocortex, in infarcted animals the paired-pulse inhibition was significantly reduced or even absent within an area extending up to 5 mm lateral from the lesion center. The changes in paired-pulse inhibition were already present on the first day and persisted at least up to 60 days after infarction. These functional changes may contribute to neurological deficits occurring after cerebral infarcts.

Animals↗
PubMed1993

Confocal microscopy immunofluorescence localization of desmin and other intermediate filament proteins in fetal rat livers.

Immunolocalization of desmin in fetal rat livers shows that on day 12 of gestation a high number of liver cells express desmin. This number decreases from day 14 onward. On day 20 about the same density of desmin-containing cells is found in fetal rat livers as is found in adult rat livers. Desmin-containing cells show two types of labeling patterns, especially on days 12 and 13 of gestation: (a) a basketlike network of intermediate filaments throughout the whole cell, similar to the labeling pattern of cytokeratin in hepatocytes; and (b) more strongly labeled intermediate filaments developing long and slender processes between adjacent cells, close to the labeling pattern of Ito cells in adult rats. From day 14 of gestation, the first type becomes rare, and from day 18 only the second type remains. Double-labeling experiments show that coexpression of desmin and cytokeratin is found in cells of the first type on days 12, 13 and 14 of gestation. Cells containing desmin with the labeling pattern of the second type never express cytokeratin. Coexpression of vimentin and cytokeratin is never found in fetal hepatocytes, even on day 12 of gestation. Numerous nonhepatocyte cells coexpress desmin and vimentin, but some cells contain vimentin or desmin alone. In desmin-containing cells the labeling pattern is of the first type (basketlike network). These results suggest that in early stages of fetal liver development, desmin is found in two different types of liver cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Acute abdominal pain--standardized findings as diagnostic support. Results of a prospective multicenter intervention study and testing of a computer-assisted diagnosis system].

Despite powerful diagnostic tools (e.g. ultrasound, special laboratory investigations), the diagnosis of acute abdominal pain is still a considerable problem. Several studies in the UK have shown that the diagnostic accuracy can be improved by structured and standardized history taking and clinical examination and by computer-aided diagnosis. In the framework of a concerted action of the European Community we have conducted a prospective multicenter interventional trial comparing two consecutive phases: a) a baseline phase in clinical routine without additional intervention, b) a test phase with structured and standardized history and clinical examination (questionnaire, documentation programme). In addition, a computer-aided diagnostic system developed in the UK was applied to the cases in the test phase. Outcome criteria were the diagnostic accuracy of the initial and the final examiner, the perforated appendix rate, the negative appendectomy rate, the negative laparotomy rate and the rates of diagnostic errors with missing indication to operation and of delayed urgent operations. No differences could be found between the phases with respect to the outcome criteria. In the baseline phase (test phase) diagnostic accuracy was 59% (59%), diagnostic accuracy after investigation (senior examiner) was 77% (78%), perforated appendix rate was 11% (16%), negative appendectomy rate was 13% (15%), negative laparotomy rate was 7% (8%), the rate of missed urgent indications to operation was 1.1% (1.9%) and the rate of delayed urgent operations was 3.4% (2.4%). Major differences between the centers were recorded. Computer-aided diagnosis resulted in a diagnostic accuracy of 51%. The introduction of structured and standardized history taking and clinical examination has not brought any improvement of the good results in clinical routine. It is doubtful, whether existing systems of computer-aided diagnosis are able to significantly decrease the still remaining error rate of 20%.

Abdomen, Acute↗
PubMed1991

The ventilatory threshold: method, protocol, and evaluator agreement.

To evaluate the effects of different methods of detection, exercise modes, protocols, and reviewers on oxygen uptake (VO2) at the ventilatory threshold (ATge), 17 men with heart disease (mean age 59 +/- 6 years) and six healthy men (mean age 60 +/- 11 years) underwent six exercise tests on different days. Each subject performed three treadmill tests (Bruce, Balke, and ramp) and three bicycle ergometer tests (50 W/stage, 25 W/stage, and ramp) in random order. The ventilatory threshold was determined for each of the six exercise tests by three independent, blinded reviewers by means of graphic plots of three commonly used methods of determination: (1) changes in the ventilatory equivalents for VO2 and VCO2, (2) changes in end-tidal oxygen and carbon dioxide pressures, and (3) the intersection of the slope of VCO2 and VO2 (V slope). The largest variability in the ATge was observed with changes in the exercise protocol. The greatest absolute (ml/min) and percentage differences in oxygen uptake at the ATge as a result of changes in protocol, method of determination, and observers were 336 (36%), 125 (12%), and 70 (7%), respectively. The overall intraclass correlation coefficient for VO2 at the ATge among the three reviewers was 0.60 and among the three protocols was 0.85 (p less than 0.01). The V slope method of detection had consistently good agreement among reviewers and was least affected by the protocol. The variance in the ATge (excluding intersubject and error variance) accounted for by differences in protocol, method, and reviewer was 82%, 14%, and 4%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobic Threshold↗
PubMed1991

Comparison of the ramp versus standard exercise protocols.

To compare the hemodynamic and gas exchange responses of ramp treadmill and cycle ergometer tests with standard exercise protocols used clinically, 10 patients with chronic heart failure, 10 with coronary artery disease who were asymptomatic during exercise, 11 with coronary artery disease who were limited by angina during exercise and 10 age-matched normal subjects performed maximal exercise using six different exercise protocols. Gas exchange data were collected continuously during each of the following protocols, performed on separate days in randomized order: Bruce, Balke and an individualized ramp treadmill; 25 W/stage, 50 W/stage and an individualized ramp cycle ergometer test. Maximal oxygen uptake was 16% greater on the treadmill protocols combined (21.4 +/- 8 ml/kg per min) versus the cycle ergometer protocols combined (18.1 +/- 7 ml/kg per min) (p less than 0.01), although no differences were observed in maximal heart rate (131 +/- 24 versus 126 +/- 24 beats/min for the treadmill and cycle ergometer protocols, respectively). No major differences were observed in maximal heart rate or maximal oxygen uptake among the various treadmill protocols or among the various cycle ergometer protocols. The ratio of oxygen uptake to work rate, expressed as a slope, was highest for the ramp tests (slope +/- SEE ml/kg per min = 0.80 +/- 2.5 and 0.78 +/- 1.7 for ramp treadmill and ramp cycle ergometer, respectively). The slopes were poorest for the tests with the largest increments in work (0.62 +/- 4.0 and 0.59 +/- 2.8 for the Bruce treadmill and 50 W/stage cycle ergometer, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Radio-functional analysis of the cervical spine using the Arlen method. Part Three: Post-traumatic syndromes. A statistical analysis of 480 subjects.

The purpose of this study was to determine the differences in patterns of cervical mobility diagrams obtained by the Arlen method in a control population of 240 subjects and in a group of 240 patients who had previously sustained an indirect cervical trauma. The characteristics of antero-posterior mobility of the cervical spine in the control population and their variations due to age and sex are summarized. A statistical study is devoted to the amplitudes of the different vertebral segments during flexion and extension. The authors have tried to elucidate the functional features of the injured spine in its totality and at different levels in both flexion and extension. The two groups were compared in an analysis of spinal dysfunctions (hypomobility, loss of mobility, paradoxical mobility).

Adolescent↗
PubMed1989

Engraftment of T-depleted major histocompatibility complex-mismatched bone marrow in T-deficient versus natural killer-deficient recipients.

When bone marrow transplantation recipients undergo standard pre-transplant immunosuppressive therapy, engraftment failures are significantly more frequent with the use of T-depleted allogeneic donor bone marrow cells than with T cell-containing allogeneic donor bone marrow cells. The relative importance of T versus natural killer (NK) cells in the rejection process of T-depleted donor bone marrow cells remains debatable. Here, NK- and T-deficient mouse mutants were transplanted across the same major histocompatibility complex (MHC) differences with homozygous or heterozygous T-depleted bone marrow cells. Results show that under the experimental conditions described, residual host NK cells are almost exclusively responsible for the increased rejection rate.

Animals↗
PubMed1989

Radio-functional analysis of the cervical spine using the Arlen method. A study of 699 subjects. Part One: Methodology.

The authors describe successively the radiological technique and measurement method of Arlen's radio-functional analysis of the cervical spine, the characteristics of antero-posterior cervical spine mobility in a control population and the variations observed in these characteristics according to age and sex. A few typical diagrams of radio-functional analysis obtained in various types of pathology are offered as examples. The ease with the Arlen method can be used in routine practice; its diagnostic and prognostic value and its role in the follow-up of patients with cervical diseases or injuries are emphasized.

Adolescent↗
PubMed1989

Radio-functional analysis of the cervical spine using the Arlen method. A study of 699 subjects. Part Two: Paradoxical tilting of the atlas.

The authors describe a peculiar movement of the first cervical vertebra: the so-called paradoxical tilting of the atlas, which consists of extension in relation to McGregor's line during flexion of the cervical spine. This physiological phenomenon has already been reported by several authors. The purpose of this study was to determine the mean amplitude and frequency of paradoxical tilting of the atlas in subjects with no known cervical pathology and to evaluate some of the factors that may influence it. The younger the subject the more frequent and more ample this paradoxical tilting: it occurs very often before the age of 40 years and is present in more than 93% of subjects under 20. Its amplitude diminishes with age, until it is replaced by mobility in flexion.

Adolescent↗
PubMed1988

Development of the fetal rat liver: ultrastructural and stereological study of hepatocytes.

Qualitative and quantitative changes in the liver tissue composition have been studied during prenatal development of the Wistar rat by electron microscopy and stereologic methods. The absolute volume of the fetal liver is multiplied by 84 between days 13 and 20 of gestation. In the meantime, the average hepatocyte volume is multiplied by 1.5 between days 12 and 20. The volumetric fraction of hepatocytes increases from 35% of the volumetric fraction of the liver on day 12 to 66% on day 20 of gestation. The non-hepatocyte cells decrease from 49% on day 12 to 25% on day 20. By days 12 and 13, the rough endoplasmic reticulum and the Golgi apparatus are well differentiated, indicating that young fetal hepatocytes are able to synthesize and export plasma proteins. The volumetric fraction of free ribosomes decreases from 38% of the hepatocytic cytoplasm on days 12 and 13 to 6% on day 20. The mitochondrial compartment occupies about 10% of the hepatocyte cytoplasm. The mitochondria, small and round on days 12, 13 and 14, become oblong from day 18 of gestation. The shape of hepatocytes changes during the prenatal development, from potato-like on days 12, 13, 14 to cubic on day 20, with an intermediate, more spheric, stage on day 18.

Animals↗
PubMed1988

[Diagnostic chorionic biopsies in the first trimester. Report of experiences over a 2 year period].

We report about 58 ultrasonographically guided transcervical chorionic villus biopsies from January 1985 to November 1987. Maternal age greater than 35 years (n = 28), followed by trisomy 21 or 18 (n = 10) were the mean indications. Biochemically evaluation of storage diseases (n = 6) and genomically DNA-analysis because of phenylketonuria (n = 2) were combined in each case with cytogenetic diagnosis. In the other cases certain indications were the reasons for biopsy. In 52 of 58 cases we were successful in biopsies and diagnoses. In the other 6 biopsy specimen we didn't found chorionic villi. 3 abortions we observed up to day 3 after operation (n = 3) and after 6 weeks (n = 1). Pathological findings were 1 trisomy 16, 1,47,XYY-karyotype and 1 embryo with phenylketonuria. Another reason for termination of pregnancy was male karyotype in a Morbus Duchenne-risk and 1 risk for Rett-syndrome. Meanwhile 30 healthy babies were born.

Adult↗
PubMed1986

[Significance of mean arterial blood pressure in the 2d trimester and the roll-over test for gestosis screening in normal, overweight and underweight primigravid patients].

Possibility of early diagnosis of pregnancy-induced hypertension via mean arterial pressure (MAP-2) and roll-overtest (ROT) was investigated in 80 normal, overweight or underweight primigravidae. The positive and negative predictability, the sensitivity, specificity and effectivity did not correspond to the efficiency of a good screening method. Obese primigravidae have more positive tests than normal. In the MAP-2 this was due to methodical errors, whereas in the ROT hydrostatic mechanisms interferet according to the overweight of the tested person. With these two screening tests, very early PIH diagnosis is generally not possible.

Adult↗