Biomedical subjects

J Fuerst

Publications and source records attributed to J Fuerst.

6 recordsLinked to original sources

PubMed2003

Anaerobic ammonium oxidation by marine and freshwater planctomycete-like bacteria.

Recently, two fresh water species, " Candidatus Brocadia anammoxidans" and " Candidatus Kuenenia stuttgartiensis", and one marine species, " Candidatus Scalindua sorokinii", of planctomycete anammox bacteria have been identified. " Candidatus Scalindua sorokinii" was discovered in the Black Sea, and contributed substantially to the loss of fixed nitrogen. All three species contain a unique organelle--the anammoxosome--in their cytoplasm. The anammoxosome contains the hydrazine/hydroxylamine oxidoreductase enzyme, and is thus the site of anammox catabolism. The anammoxosome is surrounded by a very dense membrane composed almost exclusively of linearly concatenated cyclobutane-containing lipids. These so-called 'ladderanes' are connected to the glycerol moiety via both ester and ether bonds. In natural and man-made ecosystems, anammox bacteria can cooperate with aerobic ammonium-oxidising bacteria, which protect them from harmful oxygen, and provide the necessary nitrite. The cooperation of these two groups of ammonium-oxidising bacteria is the microbial basis for a sustainable one reactor system, CANON (completely autotrophic nitrogen-removal over nitrite) to remove ammonia from high strength wastewater.

Anaerobiosis↗

PubMed2001

Microbiology and application of the anaerobic ammonium oxidation ('anammox') process.

Ten years ago, an anaerobic ammonium oxidation ('anammox') process was discovered in a denitrifying pilot plant reactor. From this system, a highly enriched microbial community was obtained, dominated by a single deep-branching planctomycete, Candidatus Brocadia anammoxidans. Phylogenetic inventories of different wastewater treatment plants with anammox activity have suggested that at least two genera in Planctomycetales can catalyse the anammox process. Electron microscopy of the ultrastructure of B. anammoxidans has shown that several membrane-bounded compartments are present inside the cytoplasm. Hydroxylamine oxidoreductase, a key anammox enzyme, is found exclusively inside one of these compartments, tentatively named the 'anammoxosome'.

Anaerobiosis↗

PubMed2001

Na(+)/H(+)exchangers: linking osmotic dysequilibrium to modified cell function.

The Na(+)/H(+) exchangers (NHEs) are among the major ion transporters involved in cell volume regulation. NHE activation leads to a cellular influx of Na(+) ions and extrusion of H(+) ions, which are readily replenished from intracellular buffers. This will result in a net import of Na(+). In many systems NHE operates in parallel to Cl(-)/ HCO3(-) exchange, resulting in cellular uptake of NaCl. The influx of osmotically obliged water will consequently lead to cell swelling. This makes NHEs suitable to serve as powerful mechanisms for increasing cell volume (CV). The low volume threshold for NHE activation enables the cells to respond to very minute reductions of the CV. By the coupling to the export of H(+) ions cell volume regulatory NHE activation may lead to changes in intracellular pH. On the other hand NHEs are activated by a broad variety of ligands and by intracellular acidosis, which, in turn, may consequently lead to cell swelling. In addition, NHEs are linked to other intracellular proteins and structures, like e.g. the cytoskeleton, which themelves are involved in the regulation of numerous cellular processes. Therefore NHEs link CV regulation to a diversity of cellular functions, both in physiological and pathophysiological conditions. Six isoforms of the Na(+)/H(+) exchanger, termed NHE1--6, have been cloned so far. NHE 1--5 are located in the plasma membrane, whereas NHE6 is sorted to the mitochondrial membrane. NHE1 and NHE6 are the ubiquitously expressed isoforms. The expression of the isoforms NHE2 to NHE5 is restricted to specific tissues and the pattern of their expression, as well as their subcellular localization indicate that they fulfill specialized functions. Cell shrinkage induced activation has been shown for NHE1,2 and 4. In contrast, NHE3 is inhibited by cell shrinkage. In many cells several isoforms are present and assigned to specific membrane domains where they may serve a functional crosstalk between the different ion transporters.

Amino Acid Sequence↗

PubMed1997

Effect of active immunization against luteinizing hormone-releasing hormone on the androgen-sensitive Dunning R3327-PAP and androgen-independent Dunning R3327-AT2.1 prostate cancer sublines.

BACKGROUND: The objective of this study was to determine the effect of active immunization against LHRH on the growth characteristics and histology of subcutaneously implanted tumors of the androgen-sensitive Dunning R3327-PAP and androgen-independent R3327-AT2.1 rat prostate adenocarcinoma sublines. RESULTS: We herein demonstrate that 1) active immunization with an LHRH-diphtheria toxoid-conjugate (LHRH-DT) leads to the downregulation of gonadotropins and testosterone and consequently the atrophy of testosterone-dependent organs such as the testes, prostate, and androgen-sensitive Dunning R3327-PAP tumors, 2) growth inhibition of Dunning R3327-PAP tumors is caused by suppression of cell division rather than by an increase in cell death and is associated with an increase of the tumor stroma content, and 3) volume increase of the androgen-independent Dunning R3327-AT2.1 tumor is slightly but significantly reduced, indicating a local stimulatory LHRH loop within this tumor cell line.

Analysis of Variance↗

PubMed1991

Effects of self-management training and reinforcement on the transfer of improved conduct in the absence of supervision.

The instruction, maintenance, and transfer of training of social skills of 3 seriously emotionally disturbed adolescents were accomplished by a self-management training and reinforcement package. During baseline sessions these students, who were covertly filmed in their classroom, averaged over 90% off-task or socially inappropriate behavior while their teacher was out of the room. They showed similar behaviors when walking between classes, unattended by their teacher. Treatment was introduced in the classroom and consisted of social skills and self-management training and reinforcement. Treatment procedures included instruction, modeling, and role playing of social skills, as well as self-assessment, self-recording, and self-reinforcement for correct approximations of these skills. After 5 weeks of training, all subjects demonstrated substantial improvements in the classroom during the teacher's absence and when distracted by other students; however, transfer of social skills did not occur to the between-class setting until students were given explicit instruction to initiate self-managing procedures in this setting.

Adolescent↗

PubMed1979

Bullous disease of childhood.

Bullous disease of childhood (BDC) is a persistent or recurrent blistering skin disease characterized by large, tense bullae in a generalized distribution, but with a predilection for the scalp, trunk, pubis, and inner thighs. It usually begins in the first decade of life and spontaneously remits after several months to three years of activity. Sulfapyridine or dapsone therapy usually controls the disease. Administration of corticosteroids for systemic effects should be avoided.

Basement Membrane↗