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At least 217 records · Page 12Linked to original sources

Membrane knobs of unfixed Plasmodium falciparum infected erythrocytes: new findings as revealed by atomic force microscopy and surface potential spectroscopy.

Cerebral malaria, a severe complication of malaria, is caused by the obstruction of cerebral microvessels by Plasmodium falciparum-infected erythrocytes. Such cells adhere to endothelial cells by means of "knobs" induced on the red cell membrane by the parasites. When atomic force microscopy was used to investigate the structure of the knobs of unfixed infected red cells, each knob was found to consist of two distinct subunits, knob components that have never been seen in chemically fixed knobs examined by conventional transmission electron microscopy. Surface potential spectroscopy revealed that the knobs have a positive charge (+20 mV), whereas the remainder of the red cell plasma membrane is negatively charged. Since endothelial plasma membranes have a negative charge, the charge difference between knobs and endothelium may play a significant role in cytoadherence between the two cell types. The subunit structure of the knobs may be a steric necessity to align adherence molecules so that they can exert their effect. This study shows that the atomic force microscope has great potential for examination of cells in their native state; in combination with surface potential spectroscopy, it may uncover fundamental processes and mechanisms in cell function.

Animals↗

Finding New Meanings: Children's Recognition of Interpretive Ambiguity in Text

This research was designed to investigate children's developing ability to detect one form of interpretive uncertainty, specifically, that a text passage could support two alternative interpretations. Three experiments were conducted with second graders (7- to 8-year-olds) and fourth graders (9- to 10-year-olds), using brief text passages designed to suggest two interpretations about the cause of a target event. The results indicated that older children were significantly more likely to report two interpretations of the passages. Children in both grades reported more second interpretations when the text information was presented as a narrative rather than as an expository passage. Children's initial interpretations generally reflected the causal information most recently encountered in the passage.

Journal Article↗

The role of neurosurgical interventions for control of spasticity in neurorehabilitation: new findings on functional microanatomy of the tibial nerve.

Harmful spasticity after cerebral or spinal damage disturbs functional recovery in neurorehabilitation, but neurosurgical interventions for relief of spasticity are not widely performed, at least in Asian countries including Japan. We have been performing various types of neurosurgical treatment for spasticity such as selective peripheral neurotomy, selective dorsal rhizotomy, microsurgical DREZotomy, and intrathecal baclofen administration. We deal with both children and adults. From our experience of tibial neurotomy, in particular, we describe functional microsurgical anatomy of the tibial nerve in the popliteal fossa. This is the first report on this regional functional anatomy.

Electric Stimulation↗

[New findings on the structure of chromosomes (author's transl)].

The structural element of eukaryotic chromosomes is the chromatin fibre consisting of histones and DNA. The chromatin fibre is about 100--200 A thick. One chromatid is built up from one chromatin fibre running through from one end to the other and laid in numerous irregular foldings. The chromatin fibre is a chain of nucleosomes. These are globular histone bodies around which the DNA winds. Nucleosomes can be observed in isolated chromatin fibrils as well as in thin sections of chromosomes after different modes of fixation. Prophasic chromosomes or early premature condensed chromosomes are thin uncoiled threads. With chromosome condensation a major coiling is seen. No constant regular arrangement of the chromatin fibril besides the major coils is observed. A rather diffuse decondensation takes place in ana- and telophase.

Animals↗

Blood protein conjugates and acetylation of aromatic amines. New findings on biological monitoring.

Internal stress of aromatic amines has so far been evaluated by their determination in blood or urine and by the degree of methemoglobin formation. Animal experiments have shown that these materials can form adducts and conjugates with proteins and nucleic acids. Our investigations show that these processes can also occur in human metabolism. For this the degree of such a formation of protein conjugates depends on an individually different potential for acetylation. In a positive sense it influences the magnitude and the rate of renal excretion of aminoaromates and their conjugates and metabolites formed by this metabolism. In contrast, only free nonacetylated aminoaromates can lead to the formation of conjugates with hemoglobin. These aminoaromates or their metabolites can then be detected quantitatively in intact erythrocytes during their lifespan. The degree of this protein conjugate formation correlates inversely with the magnitude of the acetylation potential depending on the availability of free non-acetylated aminoaromates. According to these results a clearer assessment of past stress or the presence of strain can be obtained with Biological Monitoring by a single determination of such hemoglobin adducts rather than by the traditional quantitative determination of aminoaromates or their metabolites in blood and/or urine or the methemoglobin concentration.

Acetylation↗

New findings in the development of Babesia (Theileria) equi (Laveran, 1901) in the salivary glands of the vector ticks, Hyalomma species.

The development of the piroplasm Babesia equi was studied by light microscopy in the salivary glands of three different Hyalomma species during and after the engorgement of nymphs on experimentally infected horses and after adults had fed on a vertebrate host following ecdysis. The stock of B. equi used was isolated from a horse imported from Turkmenistan (CIS) in 1991. The findings, being identical in all three Hyalomma species, differ with regard to the chronological order of the development stages in several respects from the results of previous studies based upon light or electron microscopy. A first sporogony phase of B. equi was found to develop in the salivary glands of the engorged nymphs before the ticks moulted to adults. Beginning at day 6 postinfestation (p. infest.) of the nymphs, spindle-shaped sporozoites appeared to be formed by both rapid sequential fission of a multinucleated complex and a process of radial budding from multiple fission bodies. Sporozoites isolated from the salivary glands of the engorged nymphs proved to be infectious when they were injected into a susceptible horse. After the nymphs had moulted, a second sporogony phase similar to the first one observed in the salivary glands of engorged nymphs could also be initiated in the salivary glands of adults when they were attached to a vertebrate host. Sporozoites produced in the salivary glands of adults were equally infectious for horses. Thus, two completely separate sporogony phases in B. equi seem to develop successively in the salivary glands of Hyalomma species during a transstadial transmission.

Acari↗

Two portions of the supraspinatus muscle: a new finding about the muscles macroscopy by dissection and magnetic resonance imaging.

Axial MR images of the shoulder joint reveal a central linear band within the supraspinatus muscle void of signal which seems not to represent the only tendon of this muscle. Due to the importance of the supraspinatus muscle for the painful impingement syndrome of the shoulder we studied the fibrous architecture of this muscle comparing 30 MR images and 49 cadaver dissections. We found the supraspinatus muscle to be composed of two distinct portions. The mean length of the ventral portion is 88 mm and of the dorsal portion 106 mm. The angle of the central tendon which is formed by fibers of both muscle portions relative to the frontal plane is 50 degrees. Both muscle portions probably act differently in moving the arm. This finding seems to be important for the pathophysiology of rotator cuff tears which are mainly located anteriorly within the ventral muscle portion and the eccentric central tendon.

Adult↗