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Biomedical subjects

M Donner

Publications and source records attributed to M Donner.

At least 55 records · Page 3Linked to original sources
PubMed1990

Genetics of congenital nemaline myopathy: a study of 10 families.

In order to investigate the inheritance in congenital nemaline myopathy (CNM), we studied the family histories and pedigrees of 13 patients with CNM from 10 families, and the 20 patients, by physical examination, single fibre electromyography, ultrasonography of muscles, measurement of serum creatine kinase, muscle biopsy, and electrophoresis of muscle proteins. None of the parents was affected. In three families there were two affected children. Of the parents, 15 showed deficiency of type 2B muscle fibres, and all except one father showed some other minor neuromuscular abnormality. These may represent heterozygous manifestations of recessive gene. Most of the ancestors came from sparsely populated rural communities in the west of Finland. We conclude that in the Finnish CNM patients, the mode of inheritance appears to be recessive. Apart from a few instances of dominant inheritance, most cases published also seem compatible with recessive inheritance.

Adolescent↗
PubMed1990

Fluorescence depolarization method in the study of dynamic properties of blood cells.

Fluorescence polarization is the most commonly used method to approach a property of cell membrane, the so-called "fluidity". Whether time resolved determinations may be of potential interest to get precise information on the behaviour of fluorescent probes incorporated into biological membranes, steady state measurements are still the most accessible for biologists. Steady-state anisotropy value may be considered as a semi-quantitative indication of the cohesion of the lipid chains. However, meaningful interpretation of the anisotropy values requires a careful sample preparation and a suitable use of fluorescent probes. This paper reviews the properties and uses of several hydrophobic membrane fluidity probes. In the case of intact cells, the potential interest of the association of fluorescence polarization with quenching fluorescence method in giving information on the "actual" membrane fluidity is outlined.

Diphenylhexatriene↗
PubMed1990

[Importance of membrane fluidity determination].

Translational motions of lipids and proteins and molecular motions within the lipid hydrocarbon chains of biological membranes can be approached by spectroscopic methods. The electron spin resonance (ESR) spectra of spin labels bound on proteins or grafted on fatty acids and incorporated into biological membranes undergo characteristic changes which may be resolved in terms of modifications of membrane environment. However, the method is still scarcely used in routine clinical studies. In contrast, fluorescence methods such as intermolecular excimers or fluorescence polarization might join the ranks of routine analyses. The labeling of lipid compartments with fluorescent probes and the study of their spectroscopic properties give informations on the cohesion of their immediate environment. Polyenic molecules (DPH and TMA-DPH) which are located in different lipid compartments characterize deep and superficial areas of cell membrane, respectively. A set of probes in which a 9-anthroyloxy group is attached to different positions of a long chain fatty acid provides a means of measuring a fluidity gradient into membrane bilayer. Thus, these fluorescence methods which are simple and rapid represent a semi-quantitative approach of the so called "membrane fluidity". Modifications in membrane fluidity can control the expression of proteins, receptors exposed on cell surface and alter functional properties of cells. Moreover, pathological processes can also be related to fluidity modifications. In particular, in hypertension and vascular diseases, a decrease in membrane fluidity has been shown in platelets and red cells. Nevertheless, further investigations combining biophysical, biochemical and immunological methods are needed to determine the exact relations between membrane fluidity, classical rheological properties and cell functions.

Biophysical Phenomena↗
PubMed1989

Two cases of Dandy-Walker syndrome and chronic polyneuropathy.

The paper describes a so far unreported combination of Dandy-Walker syndrome and chronic hereditary polyneuropathy in 2 boys. One of the boys has a de- and remyelinating motor and sensory polyneuropathy, with either an autosomal recessive mode of inheritence or a sporadic occurrence. The other has an autosomal dominant form of mild polyneuropathy with tomaculum formations in myelinated fibers, corresponding to hereditary neuropathy with liability to pressure palsies.

Adult↗
PubMed1989

Phagocytosis and membrane fluidity: application to the evaluation of opsonizing properties of fibronectin.

The uptake of particles by phagocytic cells involves an increase in the membrane fluidity determined by steady-state fluorescence polarization. Binding and endocytosis of target particles is in vivo enhanced by humoral factors called opsonins. In this work, fluorescence polarization was used to detect in vitro the opsonic activity of a plasma protein: fibronectin. The assay is based on the analysis of membrane fluidity variations following the uptake of gelatinized latex beads by phagocytic cells in the presence or in the absence of fibronectin. Using TMA-DPH as fluorescent probe, it was observed that the increase in membrane fluidity was enhanced in presence of fibronectin and depended upon the enhanced in presence of fibronectin and depended upon the opsonic activity was related to the integrity of the molecule. Using this method, the opsonic activity of various plasmas could be also determined.

Cell Line↗
PubMed1989

[Cell cycle analysis of hybridoma cultures: study by cytofluorimetry].

An hybridoma cell line cultivated in flasks has been used as a model to study the loss of cell viability in high density cell cultures. Cell cycle analysis by cytofluorimetry has shown that a new hypochromosomic cell population appeared as soon as the viability began to decrease. However there is no evidence that this new population is constituted of dead cells.

Animals↗
PubMed1989

[Calcium and citrate excretion by patients with calculi and healthy probands during induced acidosis].

Acidosis induced increase in renal calcium excretion and decrease in renal citrate excretion was produced by means of ammonium chloride load in 15 patients with recurrent oxalate lithiasis and in 15 control subjects. The expected increase in the calcium citrate relationship in urine is more marked and more lasting in stone patients. Stone formers obviously respond to an acidotic metabolic situation by a more clear relative decrease in citrate excretion, in addition to more intensive calcium excretion, which is known. A certain individual sensitivity of renal tubular mechanisms is discussed with regard to acid base changes.

Acid-Base Equilibrium↗
PubMed1988

Pathology of congenital nemaline myopathy. A follow-up study.

This study was undertaken to review the development over 5-18 years of pathologic changes in 13 patients (4 male and 9 female) with congenital nemaline myopathy. Follow-up biopsies were compared with earlier biopsies and with published normal values as to quantity and location of nemaline bodies, secondary signs of myopathy, and in 6 patients as to muscle fiber type and size. Biopsy findings were correlated with the mobility and muscle power of the patient. The main differences in myofiber maturation in the patients as compared with normal myofiber maturation were: (1) deficient differentiation of type 2 fibers, (2) further increase of variation in fiber size with age, and (3) skewing in early adulthood of fiber size distribution curves toward the atrophic end. In ambulant patients, this skew seemed to be compensated with a population of hypertrophic fibers. The nemaline bodies tended to be located beneath the sarcolemma in the younger patients and inside the muscle fibers in the older patients. The quantity of nemaline bodies seemed to have increased with age. The clinical deterioration and the defective myofiber maturation in the patients together with an increase in internal nuclei and endomysial fat or fibrosis indicate an active disease process. This speaks against the generally held view that congenital nemaline myopathy is static.

Adolescent↗
PubMed1988

Optic neuritis in children and its relationship to multiple sclerosis: a clinical study of 21 children.

The optic neuritis of 21 children aged between four and 14 years generally was characterized by bilateral involvement (62 per cent) and papillitis (76 per cent). Often acute infections or vaccinations were preceding events. Frequently there was pleocytosis during the disease process, with production of IgG, oligoclonal and viral antibodies, which increased during follow-up. Nine of these children (eight female) later developed multiple sclerosis, with unilateral involvement of the optic nerves and HLA Dr2 positivity. Disseminated effects on the central nervous system were similar to those of adults with multiple sclerosis. In all cases these relapses occurred within one year of the optic neuritis. EEGs did not differentiate those who developed multiple sclerosis from those who did not, but four of five patients with multiple sclerosis who were followed-up for a year or more had paroxysmal discharges, and one of the four had manifest epilepsy. Magnetic resonance imaging, visual and sensory evoked potentials and CSF studies were helpful in diagnosing multiple sclerosis. The visual prognosis was good in most cases. 17 children had no or only slight neurological disability at the end of follow-up; the other four had moderate to severe disability. This study suggests that optic neuritis is a diffuse disease, not merely affecting the optic nerves, and that the immunological events typical of multiple sclerosis can start in childhood.

Adolescent↗
PubMed1988

Prediction of early school-age problems by a preschool neurodevelopmental examination of children at risk neonatally.

A group of 350 children who had had neonatal developmental risk-factors were assessed at the age of five years with a neurodevelopmental examination. At nine years they were assessed again for neuropaediatric, motor, psycholinguistic, cognitive and school-achievement problems. (Children with major handicaps were excluded). Poor performance at age five was significantly associated with failure in the nine-year examinations and with school problems. Sensitivity of the five-year neurodevelopmental examination in predicting problems at nine years was 0.30 to 0.50, and its predictive value for an abnormal performance was 0.30 to 0.60. Predictively, the neurodevelopmental examination was accurate in defining children without later problems, but less satisfactory in defining those who did develop problems. Multiple linear regression analyses between the neurodevelopmental examination and the scores at nine years revealed low explanatory power. A shortened neurodevelopmental examination, based on the best predictors, seemed to be as efficient as the full examination.

Brain Damage, Chronic↗
PubMed1988

Erythrocyte aggregation: approach by light scattering determination.

Erythro-aggregometer is a Couette viscometer which was developed to measure aggregation parameters of red blood cells. The system is based on the analysis of the light intensity backscattered by a blood suspension. It allows to approach aggregation phenomenon in terms of kinetics, structural and rheological parameters. The measurement system designed for use with a microcomputer is suitable for both research and clinical investigations.

Blood Viscosity↗
PubMed1988

[Evaluation of an automated system of measuring erythrocyte aggregation in dysglobulinemia treated by plasma exchange].

Characteristics of a new erythrocyte aggregameter were evaluated in 7 patients with monoclonal dysglobulinemia (5 multiple myeloma, 1 Waldenström disease, 1 CLL with monoclonal immunoglobulin) treated by plasma exchange. This apparatus measures modifications of light retro-diffused by erythrocytes suspension after shear arrest. All parameters measured: Ta, Tf, S10, gamma D, gamma S were modified after plasma exchange: either immediately after the first or after the second or third plasma exchange. These findings demonstrate the value of this new technique for evaluating red cell aggregation. These data should be completed by rheological assessment of dysglobulinemia treated by plasma exchange.

Automation↗
PubMed1987

Chronic relapsing course of encephalomyeloradiculopathy in a 6-year-old boy.

We present a young child with an illness characterized by remissions and exacerbations and signs of disseminated lesions in the central nervous system. Visual evoked response and brainstem auditory evoked potential gave abnormal findings showing lesions also of the optic nerves and brainstem. The CSF IgG index was slightly elevated and myelin basic protein was high. There was also intrathecal antibody production against different viruses, the highest against measles. The HLA type was A3, B7, Dr2. The T4/T8 ratio reflected an immunological active disease. All these signs could have been diagnosed as multiple sclerosis. However, there were also lower motoneuron lesions and metabolic studies showed disturbances in pyruvate metabolism as in Leigh's disease. Cerebral tomography and magnetic resonance imaging showed scattered lesions in the nuclei lentiformis and capsula interna. We would like to stress the importance of careful etiological studies in cases of MS in childhood.

Brain Diseases, Metabolic↗
PubMed1987

On diffusion in organized assemblies and in biological membranes.

The following paper is a brief presentation of problems related to the concepts of diffusion coefficient D and so-called viscosity eta used to characterize the cohesion of biological membranes. The first approach to this problem is a recall of the definition of D and eta in liquids. It appears that the models developed with exogenous probes to account for the diffusion-viscosity relationship are not verified in membranes. The existence of complex diffusional mechanisms, the influence of the size of the probe are presented. The results of a model calculation suggest that there is no direct correlation other than great simplifications, between the diffusion coefficient and viscosity. The calculations are then extended to actual biological assemblies and the influence of proteins on the motion of the probe considered. The limitations of the methods involving exogenous probes for determining the cohesion of biological membranes are discussed.

Cell Membrane↗
PubMed1985

Fluorescence polarization applied to cellular microrheology.

The fluorescence polarization of probe molecules gives information on the "fluidity" of probe environment. Although the data cannot be related with absolute values of microviscosity, the method is largely used for probing the "fluidity" of lipid regions of biological membranes. Therefore, fluorescence polarization is of interest in clinical research, for membrane alterations are associated with either pathological processes of red cells, platelets, leukocytes or important cell functions.

Blood Platelets↗
PubMed1985

Comparative study on fluorescent probes distributed in human erythrocytes and platelets.

Important cellular functions, such as rheological properties of cells are presumably related to the membrane lipid fluidity which may be approached by the use of fluorescence polarization method. However, biological membranes represent very heterogeneous media and the knowledge of the fluidity of membrane compartments requires the use of different probes. Two fluorescent probes, DPH and its cationic derivative, TMA-DPH, have been employed to probe the lipid fluidity of human platelets and red cell membranes. The results show that the informations given by DPH and TMA-DPH can present important differences, suggesting that DPH and TMA-DPH are localized in different regions of cell membranes. In an attempt to investigate relations between lipid fluidity and rheological properties of red cells, the behavior of probes was studied in a "Couette" viscometer with a device for studying the emissive properties of probes when red cell membranes are under shear conditions.

Blood Platelets↗
PubMed1984

Allogeneic bone marrow transplantation in man: in vitro activity of FTS-Zn on T-cell markers and functions.

Thymulin (FTS-Zn) is a synthetic metallo-nonapeptide similar to the serum factor of thymic origin FTS, which induces the maturation of lymphoid cells. The activity of this compound on peripheral blood mononuclear cells from 12 bone marrow recipients was studied in vitro. It was demonstrated that thymulin was able to induce or modulate the expression of T-cell membrane markers, to enhance the proliferative responsiveness of lymphocytes to mitogens or allogeneic cells, and to increase mononuclear cells' natural killer activity. This in vitro responsiveness was contemporary to a transient decrease of FTS levels in the patients' serum, documented by sequential assays. These results suggest that thymulin could be of interest as a prophylactic therapy to speed up the immunological reconstitution of bone marrow recipients.

Adolescent↗