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Biomedical subjects

M Schlegel

Publications and source records attributed to M Schlegel.

At least 19 recordsLinked to original sources
PubMed2003

An RAPD (random amplified polymorphic DNA) analysis of genetic population structure of Balea biplicata (Gastropoda: Clausiliidae) in fragmented floodplain forests of the Elster/Saale riparian system.

Eight German populations of the land snail Balea biplicata (Mollusca: Clausiliidae) were studied using the randomly amplified polymorphic DNA-polymerase chain reaction and morphometrics (principal component and discriminant analysis) to examine population structure and gene flow patterns in a fragmented landscape mosaic along the Elster/Saale riparian system, Germany. A variety of population genetic analyses targeting either more on the geographic scale of gene flow (genetic distances, F statistics, Mantel test) or on local genotypic structure (heterozygosity, linkage disequilibrium, bottleneck probability) showed that (1) the population system in total is governed by high gene flow independent of geographic distance, (2) genetic structure on the narrower sampling scale is mainly determined by stochastic processes due to genetic drift in small isolated and frequently recolonized populations, and (3) the morphometrical variation of the populations was related neither to habitat nor to genetic heterogeneity. The potentials for active and passive dispersal capacity of the snails and possible environmental impacts on their population structure are discussed.

Animals↗
PubMed2001

Ni clay neoformation on montmorillonite surface.

Polarized extended X-ray absorption fine structure spectroscopy (P-EXAFS) was used to study the sorption mechanism of Ni on the aluminous hydrous silicate montmorillonite at high ionic strength (0.3 M NaClO4), pH 8 and a Ni concentration of 0.66 mM. Highly textured self-supporting clay films were obtained by slowly filtrating a clay suspension after a reaction time of 14 days. P-EXAFS results indicate that sorbed Ni has a Ni clay-like structural environment with the same crystallographic orientation as montmorillonite layers.

Journal Article↗
PubMed2001

Molecular evolution of the small subunit ribosomal DNA in woodlice (Crustacea, Isopoda, Oniscidea) and implications for Oniscidean phylogeny.

The small subunit ribosomal DNA (ssu rDNA) of 13 isopods was sequenced. The entire length of the ribosomal gene is unusually long, resulting from the presence of five expansion elements accounting for more than 40% of the gene. We found that in terrestrial isopods the length of the ssu rDNA ranges from 2414 bp (Ligidium hypnorum) to 3537 bp (Cubaris murina). This is the longest metazoan ssu rDNA reported to date. The conserved regions are highly informative for analysis of the early nodes of the tree, whereas the variable expansion elements are better suited to reconstruction of the branching pattern between closely related taxa. The suggested relationship among Synochaeta, Crinochaeta, and Diplochaeta based on the conserved regions confirms that based on previous morphological analyses. In contrast, the phylogeny within the Crinochaeta based on the entire ssu rDNA including the variable domains is in conflict with that based on most of the morphological analyses. The phylogenetic analyses of the ssu rDNA support a repeated independent evolution of the three different types of pleopodal lungs in the Crinochaeta.

Amino Acid Sequence↗
PubMed2001

Phylogenetic relationships within the class Spirotrichea (Ciliophora) inferred from small subunit rRNA gene sequences.

The small subunit rDNAs of five species belonging to the Euplotidae and eight species of the Oxytrichidae were sequenced to obtain a more detailed picture of the phylogenetic relationships within the Spirotrichea (Ciliophora). Various tree reconstruction algorhythms yielded nearly identical topologies. All Euplotidae were separated from the other Spirotrichea by a deep split. Further, a large genetic distance between the marine genus Moneuplotes and the freshwater species of Euplotoides was found. Differences between the methods used occurred only within the Oxytrichidae. Whereas the monophyly of the Stylonychinae was supported in all trees, the monophyly of the Oxytrichinae was not. However, the molecular data support the morphological and ontogenetic evidence that the pattern of 18 frontal-ventral-transversal cirri evolved in the stemline of the Oxytrichidae and was modified several times independently. Our results are also in agreement with taxonomic revisions: the separation of both Sterkiella nova from Oxytricha and Tetmemena pustulata from Stylonychia.

Animals↗
PubMed2000

Malfunction of a unipolar pacemaker system following development of marked subcutaneous emphysema.

Failure of a unipolar pacemaker system due to subcutaneous emphysema is a rare but potentially life-threatening complication after implantation. We report on a pacemaker dysfunction observed three days after implantation in a 91-year-old patient following development of marked subcutaneous emphysema. Function was immediately restored following application of pressure bandages and the condition resolved within a few days.

Aged↗
PubMed1999

Evidence for the Formation of Trioctahedral Clay upon Sorption of Co(2+) on Quartz.

The sorption mechanism of Co on quartz at room temperature has been investigated by an in-depth analysis of published extended X-ray absorption fine structure (EXAFS) spectroscopy and solution chemistry data. In particular, the 3.5-5 Å mid-range atomic environment of Co has been determined with unprecedented precision by combining ad initio FEFF7.02 calculations and results obtained by polarized EXAFS on the mid-distance structure of sheet silicate minerals. The local atomic environment around sorbed Co atoms is identical to that of Co in trioctahedral clays and substantially different from that in the cobalt hydroxide Co(OH)(2(s)). Neoformation of a trioctahedral clay is consistent with calculated thermodynamic solubilities, which indicate that 2:1 and 1:1 Co-rich hydrous silicates, similar to kerolite and chrysotile, are less soluble than Co(OH)(2(s)). Consequently, precipitation of Co-rich clay is favored over that of Co(OH)(2(s)) at pH values below 9 and for a dissolved Si concentration equal to quartz solubility. New experimental data show that dissolved Si concentrations can approach, and even exceed, that of quartz solubility during the short times of sorption experiments. Based on the available data, it is not possible to conclude unequivocally if the Co layer silicate grew epitaxially on the quartz surface, topotactically in a surface amorphous layer, or independently of the quartz framework structure. The structural and chemical interpretation is supported by recent published studies in which sorption of a hydrolyzable cation leads to the neoformation of a mixed layer phase formed from the sorbate species and the sorbent metal. This surface-induced precipitation mechanism is a general phenomenon that may account for the formation of secondary clays as coatings on silicates. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Analysis of the complete mitochondrial DNA sequence of the brachiopod terebratulina retusa places Brachiopoda within the protostomes.

Brachiopod phylogeny is still a controversial subject. Analyses using nuclear 18SrRNA and mitochondrial 12SrDNA sequences place them within the protostomes but some recent interpretations of morphological data support a relationship with deuterostomes. In order to investigate brachiopod affinities within the metazoa further, we compared the gene arrangement on the brachiopod mitochondrial genome with several metazoan taxa. The complete (15 451 bp) mitochondrial DNA (mtDNA) sequence of the articulate brachiopod Terebratulina retusa was determined from two overlapping long polymerase chain reaction products. All the genes are encoded on the same strand and gene order comparisons showed that.only one major rearrangement is required to interconvert the T. retusa and Katharina tunicata (Mollusca: Polvplacophora) mitochondrial genomes. The partial mtDNA sequence of the prosobranch mollusc Littorina saxatilis shows complete congruence with the T. rehtusa gene arrangement with regard to the ribosomal and protein coding genes. This high similarity in gene arrangement is the first to be reported within the protostomes. Sequence analyses of mitochondrial protein coding genes also support a close relationship of the brachiopod with molluscs and annelids, thus supporting the clade Lophotrochozoa. Though being highly informative, sequence analyses of the mitochondrial protein coding genes failed to resolve the branching order within the lophotrochozoa.

Animals↗
PubMed1999

Phylogenetic relationships of orders within the class colpodea (Phylum ciliophora) inferred from small subunit rRNA gene sequences

Molecular analyses have been used recently to refine our knowledge of phylogenetic relationships within the ciliated protozoa (phylum Ciliophora). A current Hennigian phylogeny of the orders in the class Colpodea, based on light and electron microscopic analyses, makes three important assumptions with regard to apomorphic character states, namely, (1) that the kreyellid silver line evolved early in colpodean phylogeny, separating bryometopids, such as Bryometopus, from all other colpodeans; (2) that the macro-micronuclear complex is an autapomorphy of the cyrtolophosidids, such as Platyophrya; and (3) that merotelokinetal stomatogenesis is an apomorphic character of colpodids, such as Colpoda, Bresslaua, and Pseudoplatyophrya. These predictions of relationships within the class Colpodea were investigated by determining the complete small subunit rRNA gene sequences for the colpodid Bresslaua vorax, the grossglockneriid Pseudoplatyophrya nana, and the cyrtolophosidid Platyophrya vorax and a partial sequence for the bryometopid Bryometopus sphagni. These sequences were combined with the previously published complete SSrRNA sequences for the colpodid Colpoda inflata and the bursariomorphid Bursaria truncatella. The affiliations were assessed using both distance matrix and maximum-parsimony analyses. The tree topologies for the class Colpodea were identical in all analyses, with bootstrap support for bifurcations always exceeding 60%. The results suggest the following. (1) Since the clade including Bryometopus and its sister taxon, Bursaria, is never basal, the kreyellid silver-line system evolved later in colpodean phylogeny and does not separate bryometopids from all other colpodeans. (2) Since Platyophrya is always the sister taxon to the other five genera, there is a fundamental phylogenetic significance for its macro-micronuclear complex. (3) Since the colpodids, Colpoda, Bresslaua, and Pseudoplatyophrya, always group in one clade, merotelokinetal stomatogenesis appears to be a derived character state.

Journal Article↗
PubMed1998

Phylogenetic relationships between prostome and colpodean ciliates tested by small subunit rRNA sequences.

We analyzed the phylogenetic relationships among the four ciliate classes, Prostomatea, Colpodea, Nassophorea, and Litostomatea, by small subunit ribosomal RNA gene sequence comparison to test several phylogenetic hypotheses that had been proposed for these classes, based on ultrastructural features. The complete coding regions of the prostomes, Prorodon teres and Coleps hirtus, and of the colpodean, Bursaria truncatella, were determined and compared to the database and the literature. The prostomes and colpodeans are strongly supported as monophyletic groups in all analyses. A sister-group relationship between prostomes and colpodeans is strongly supported by parsimony analyses and moderately supported by distance matrix analyses. There was no support for a close relationship between colpodeans and nassophoreans or between colpodeans and litostomes. In all analyses, these four classes branch late in the ciliate tree. This finding further supports the new view of ciliate phylogeny that so-called ancestral taxa, such as the "primitive" prostomes, are in fact derived and that so-called "highly evolved" groups, such as the heterotrichs, branch off very early in the ciliate tree.

Animals↗
PubMed1998

Evolution of histone H4 and H3 genes in different ciliate lineages.

The histones H4 are known as highly conserved proteins. However, in ciliates a high degree of variation was found compared both to other eukaryotes and between the ciliate species. To date, only H4 histones of species belonging to two distantly related classes have been investigated. In order to obtain more detailed information on histone H4 variation in ciliates we undertook a comprehensive sequence analysis of PCR-amplified internal H4 fragments from 12 species belonging to seven out of the nine currently recognized ciliate classes. In addition, we used PCR primers to amplify longer fragments of H3 and H4 genes including the intergenic region. The encoded amino acid sequences reveal a high number of differences when compared with those of other eukaryotes and the ciliate species investigated. Furthermore, in some species H4 gene variants were detected, which result in amino acid differences. The greatest number of substitutions and insertions found was in the amino terminal region of the H4 histones. However, all sequences possess a conserved region corresponding to those of all other eukaryotic H4 histones. The histone gene variations were used to reconstruct phylogenetic relationships. The tree from our data matches perfectly with the ribosomal RNA data: The heterotrichs, which were considered as a late branching lineage, diverge at the base of the ciliate tree and groups formerly thought to represent ancestral lineages now appear as highly derived ciliates.

Amino Acid Sequence↗
PubMed1994

Community health nursing in the 1990s--risky business?

The atmosphere in which community health nurses (CHNs) work in city, suburban, and rural neighborhoods has become increasingly dangerous. Using Neuman's Systems Theory, four graduate students surveyed CHNs from three certified home health agencies to ascertain the real and perceived safety risks which these workers face daily. The response from all three agencies was similar as the nurses identified several situations in which they felt that their safety was compromised. As a result of the information gathered, a Community Risk-Reduction Plan was formulated.

Community Health Nursing↗
PubMed1991

Molecular evolution in hypotrichous ciliates: sequence of the small subunit ribosomal RNA genes from Onychodromus quadricornutus and Oxytricha granulifera (Oxytrichidae, Hypotrichida, Ciliophora).

The small subunit ribosomal RNA (16S-like rRNA) coding regions of the hypotrichous ciliates Onychodromus quadricornutus and Oxytricha granulifera were amplified using polymerase chain reaction techniques. Complete sequences were determined for the amplified genes and compared to those of other ciliated protozoa. In phylogenetic trees inferred using distance matrix methods oxytrichids are not seen as a cohesive phylogenetic group. Oxytricha nova is most closely related to Stylonychia pustulata in a lineage that also includes O. quadricornutus. This phylogeny contradicts phylogenetic schemes in which Onychodromus is considered to be a primitive hypotrichous ciliate and suggests that O. nova was misidentified as members of the genus Oxytricha.

Animals↗
PubMed1983

[Objectification of the training effect of sports therapy for wheelchair users].

The effects of an additional six-weeks training program were investigated ergometrically and in practice in 10 paraplegics. In order to develop stamina, strength and coordinative abilities, the load components were varied by increasing training frequency, expanding load range and increasing stimuli density. It was possible to show a significant increase in the general physical capacity. The performance parameters of paraplegics were compared with those of wheelchair-bound sports competitors and able-bodied persons. It was possible to improve the capacity of skeletal muscles and bring it closer to that of competitive athletes and able-bodied persons. Trained paraplegics as well as competitive athletes both display to the same extent a conspicuously poorer cardiovascular capacity in relation to able-bodied persons. The reason for this is believed to lie in the extensive muscular and vascular deficiency due to the particular disablement and the poorer venous return resulting from the latter. It points to a reduced overall blood volume and a relatively small heart volume. These investigations are being continued. The findings of sports medicine necessarily require that continuous training take place with relatively high intensity for the purpose of producing a circulatory effect. On the other hand, a basic stamina training must ensure that the indicated capacity reserves of skeletal muscles are developed. The multifaceted possibilities for training within the framework of sport for the disabled are presented.

Adolescent↗