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Biomedical subjects

J Hartman

Publications and source records attributed to J Hartman.

At least 73 records · Page 4Linked to original sources
PubMed1983

Enzyme activity pattern in developing mouse brain in situ in embryonic brain aggregated cells at 37 degrees C and 0 degree C.

In aggregates of nervous tissue, cultivated for 1--7 days at 0 degree C and 37 degrees C, respectively, the activities of seven enzymes of energy liberating metabolism were estimated, in order to evaluate their metabolic "profiles" and changes during cultivation. The enzymes used as markers of different pathways of energy liberation from substrates were: lactate dehydrogenase - LDH - (EC 1.1.1.27), triose-3-phosphate dehydrogenase - TPDH - (EC 1.2.1.12), glycerol-3-phosphate dehydrogenase - GPDH - (EC 1.1.1.8), hexokinase - HK - (EC 2.7.1.1.), malate:NAD dehydrogenase - MDH - (EC 1.1.1.37), citrate synthase - CS - (EC 4.1.3.7), and 3-hydroxyacetyl CoA dehydrogenase - HOADH - (EC 1.1.1.35). During the cultivation, some changes in the metabolic "profiles" were observed. Although some of these changes as well as the differences between the cultivation at 0 degree C and 37 degrees C, were statistically significant, they were not greater than the variations between different samples of any tissue taken at different times. They were not, therefore considered to be of major significance. However, all the aggregates exhibited "profiles" characteristic for the nervous tissue, with relatively very high activity of HK, high activity of MDH and CS (carbohydrate breakdown) and low activity of GPDH and HOADH (lipid catabolism).

Animals↗
PubMed1981

Measurement of early spontaneous recovery from aphasia with stroke.

The amount of spontaneous change in aphasia was quantified in 44 right-handed patients who were aphasic following a first and unihemispheric stroke. All were initially tested less than 14 days after onset and were reevaluated at a mean of 30 days. The Porch Index of Communicative Ability was administered for objective and precise measurement. Forty-one of the patients demonstrated significant improvement, a finding which must be taken into account in evaluating any claims for effectiveness of speech therapy.

Adult↗
PubMed1981

Adhesion of dissociated mouse embryonic brain cells. A new method of quantitative evaluation.

The adhesion of mouse embryonic brain cells was measured in a rotating chamber. A method is proposed for quantitative evaluation of adhesion kinetics. Dissociated cells were incubated in a planparallel chamber and pictures were taken between time 0-120 min. Film negatives were evaluated by computer--controlled scanning. Ten thousand individual data area obtained from one frame and 1,000 levels of absorbency are distinguished. A method is described which allows the discrimination of area, density and the shape of adhering cells. The influence of the dissociation procedure on cellular adhesion was studied. Short trypsinisation (0.025% trypsin for 5 min) followed by sieving was most favourable for adhesion. Mechanical sieving and dissociation with EGTA (Ca2+ chelator) gave less satisfactory results. Significantly diminished adhesion was observed after prolonged trypsinisation. If cells were incubated in media lacking Ca2+, adhesion was significantly inhibited. The kinetics of adhesion follows the curve of flocculation kinetics independently of the dissociation procedure and composition of the medium.

Animals↗
PubMed1981

Reaggregation of human, chick, and human embryonic brain cells. Factors influencing the formation of a histiotypic unit.

1. Aggregation of embryo human, mouse, and chick brain cells was studied. The optimum age interval of donors from different species was determined. 2. The significance of different dissociation procedures (mild trypsinisation followed by sieving, trypsinisation + DNA digestion, mechanical dissociation in 1 or 2 steps, and Ca2+ chelation by EGTA) for the rate of aggregation was estimated. A significant reduction of aggregation was observed after one step mechanical dissociation. Nonspecific adhesion of cells on DNA molecules was found only during the first stages of aggregation. 3. The curve of aggregation kinetics follows the curve of floculation kinetics. 90% free cells disappear from the medium after 2 h of aggregation and a large number of microaggregates are formed which condense after 20 to 24 h into compact aggregates. The time course of aggregation was similar for all cells dissociated by different means. Small differences in the rate of aggregation, caused by dissociation procedures, were apparent only during the first stages of aggregation. 4. The histiotypic unit formed by aggregation of human, mouse, and chick embryo brain cells exhibits some common and some specific features. During aggregation a multiple structural reconstruction takes place and a limited number of cells are exchanged or sorted out from aggregates into the medium. 5. The structural organisation of aggregates from differently dissociated cells differs in several aspects. This indicates that membrane surface structures are influenced differently by dissociation and behave differently during distinct stages of aggregation.

Animals↗
PubMed1973

Fiber formation and myelinization of cultivated dissociated neurons from chicken dorsal root ganglia: an electron microscopic and scanning electron microscopic study.

Dissociated neurons from chicken embryo dorsal root ganglia were cultivated in Rose chambers for up to 5 weeks. Newly formed fibers appeared as single fibers or grouped in bundles. During the first week of cultivation microtubules and microfilaments were frequently observed. The diameters of the fibers increased progressively and a number of varicosities appeared. In some distal portions of fibers large vesicles could be observed. During the second week in culture Schwann cells were easily recognized. They appeared as both dark and light cells. During this period myelinization of some fibers was seen to commence. High glucose concentrations were not observed to influence the process of myelinization. Essentially the important factors were the number of cells present in the culture and also the presence of NGF in the medium. Schwann cells myelinated nerve fibers exclusively. Two types of abnormalities in myelin formation were recognized: one Schwann cell myelinating two fibers and one fiber being myelinated twice, by two Schwann cells. Concomitantly with myelinization, myelin degeneration was observed. Histiotypic fascicles, typical constituents of the outgrowth zone of cultivated intact dorsal root ganglia, bundles of fibers, surrounded by connective tissue, are not formed. The surface ultrastructure of nerve fibers, as studied by scanning EM, was seen to be covered by numerous spherical elements as well as by small fibers and irregular elements. The growth cones of fibers were void of any glial contact. Myelinization occupied individual isolated segments along with nerve fibers and evidenced the absence of nodes of Ranvier. Relationships between single elements in the dissociated culture system are discussed, with respect to the possibilities for analysis of some of the elementary mechanisms of cellular and molecular interaction responsible for the development of the peripheral nervous system.

Animals↗