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Biomedical subjects

J Hartmann

Publications and source records attributed to J Hartmann.

At least 91 records · Page 5Linked to original sources
PubMed1986

Clinical alterations in relation to the morphological composition of the subgingival microflora following scaling and root planing.

The aim of the present study was to relate shifts in the composition of subgingival plaque in periodontal pockets to alterations of the clinical periodontal conditions following a single course of subgingival scaling and root planing during a period of professional supragingival plaque control. For this purpose, 36 pairs of contralateral periodontal pockets in 10 subjects with moderately advanced periodontitis were assessed for the degree of gingival inflammation, probing pocket depths, bleeding on probing, attachment levels and the amount of supragingival plaque. In addition, samples of subgingival plaque were analyzed morphologically by dark-field microscopy. All patients received detailed information about proper oral hygiene and every 1-2 weeks, professional removal of supragingivally located deposits. When the oral hygiene standard had been sufficiently improved, 1 course of subgingival scaling on 1 side of each jaw only (test side) was carried out. Clinical and microbiological examinations were repeated after the scaling as well as after 2 and 6 months, while patients were recalled for supragingival prophylaxis every 2nd to 4th week. Our data showed that a single course of subgingival scaling and root planing resulted in reduced probing depths, a gain in clinical attachment and a shift in the composition of the subgingival microflora to a composition found in relatively healthy periodontal conditions. In relatively shallow pockets, however, a possible influence of repeated sampling on the subgingival microflora could not be ruled out. Bleeding on gentle probing was a reliable parameter for predicting a subgingival microflora where motile bacteria hold an increased portion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Effect of stress on calcium homeostasis in sheep.

The acute effect of stress on the plasma and cerebrospinal fluid (CSF) immunoreactive parathyroid hormone (PTH) response was studied in 6 merino sheep. Stress was exerted by weak periodical electric square waves (PESW). In addition, the effect of intravenous injection of adrenaline was studied. Under stress conditions (PESW or adrenaline injection), plasma PTH increased up to 30% and up to 50%, respectively. Weak periodical electric square waves of 3-4 mA decreased CSF PTH concentrations by up to 50%. The effect of adrenaline injection on the CSF PTH was not significant. Total calcium and magnesium in plasma and CSF did not change. Our results showed that the effect of stress on the CSF PTH is opposite to the effect on plasma PTH, and suggest that both, PESW and adrenaline, affected PTH in plasma and CSF by a Ca-independent mechanism.

Animals↗
PubMed1984

Formation of specific amino acid sequences during carbodiimide-mediated condensation of amino acids in aqueous solution, and computer-simulated sequence generation.

Carbodiimide-mediated peptide synthesis in aqueous solution has been studied with respect to self-ordering of amino acids. The copolymerisation of amino acids in the presence of glutamic acid or pyroglutamic acid leads to short pyroglutamyl peptides. Without pyroglutamic acid the formation of higher polymers is favoured. The interactions of the amino acids and the peptides, however, are very complex. Therefore, the experimental results are rather difficult to explain. Some of the experimental results, however, can be explained with the aid of computer simulation programs. Regarding only the tripeptide fraction the copolymerisation of pyroGlu, Ala and Leu, as well as the simulated copolymerisation lead to pyroGlu-Ala-Leu as the main reaction product. The amino acid composition of the insoluble peptides formed during the copolymerisation of Ser, Gly, Ala, Val, Phe, Leu and Ile corresponds in part to the computer-simulated copolymerisation data.

Amino Acid Sequence↗
PubMed1982

Formation of specific amino acid sequences during carbodiimide-mediated condensation of amino acids in aqueous solution.

Carbodiimide-mediated peptide synthesis in aqueous solution at room temperature has been studied with respect to self-ordering of amino acids. Inasmuch as glutamic acid is readily converted into pyroglutamic acid, the peptides formed by copolymerization of glutamic acid with other amino acids are preferentially pyroglutamyl-peptides. Competition experiments were carried out to determine the influence of the amino acid side chains on the reactivity of amino acids and peptides during the dehydration condensation. The results show that the self-ordering process is controlled by both the activated carboxyl component (amino acid or growing peptide) and the incoming amino acid. A condensation of pyroglutamic acid, alanine and another amino acid component Xxx (Xxx = Gly, Val, Leu or Gly-Tyr) preferentially yielded the dipeptide pyroGlu-Ala, but the formation of the tripeptide pyroGlu-Ala-Ala became strongly reduced because of competing reactions. A simple explanation for the observed selectivities is not at hand. Polypeptides were so far only obtained when they were allowed to precipitate in the reaction system. Evidence for the non-random copolymerization of larger peptides is presented as well.

Amino Acid Sequence↗
PubMed1981

Aspartylglycosaminuria in an Italian family: clinical and biochemical characteristics.

Two members of a consanguineous Italian family are described with symptoms of aspartylglycosaminuria. Both patients exhibit mental retardation, some facial dysmorphism and discrete radiological abnormalities affecting the skull and vertebrae. Peripheral blood smears revealed multi-vacuolated lymphocytes. Enzyme studies in leukocytes showed an absence of aspartylglucosaminidase activity. Urine analysis demonstrated abnormal oligosacchariduria. Angiokeratoma corporis diffusum was observed in one patient. The disease is seen as not being limited to Scandinavia or to patients of Scandinavian descent.

Acetylglucosamine↗
PubMed1981

Formation of specific amino acid sequences during thermal polymerization of amino acids.

The mechanism of the thermal polymerization (at 180 degrees C) of glutamic acid, tyrosine, and glycine has been studied. Glutamic acid is quickly and almost completely converted into pyroglutamic acid. The only dipeptide that is formed by dimerization of the remaining two amino acids is cyclic glycyl-tyrosine (a diketopiperazine). In a secondary reaction pyroglutamic acid interacts with cyclic glycyl-tyrosine and yields pyroglutamyl-glycyl-tyrosine and pyroglutamyl-tyrosyl-glycine. Other di- or tripeptides are not observed. The preferential appearance of the two pyroglutamyl-peptides has been reported earlier by Nakashima et al. (1977). The present data explain those results. Model experiments show that cyclic glycyl-tyrosine can also be cleaved by other acids or bases. In the presence of acetic acid at 118 degrees C N-acetyl-glycyl-tyrosine is the major product. Partial hydrolysis predominantly yields tyrosyl-glycine. These effects are explained by stereospecific interactions. The results on self-ordering of amino acids during peptide formation are discussed in respect of the origin of prebiotic enzymes and genetic information.

Amino Acid Sequence↗
PubMed1981

Some methodical aspects and applications of freeze-etching in polymer research.

The freeze-etching method is used for investigating the morphology of aqueous polymer systems, e.g. network-like segregation structures of cryofixed polymer solutions and real network structures in polymer gels. The cooling rate, which is decisive for cryofixation of specimens, is measured by a thermocouple and a pyroelectric element in different coolants. The effect of the cooling rate on the freeze-etching structure of polymer solutions, polymer gels and a 10% aqueous glycerol solution as a model substance is determined and compared. The increase of the cooling rate in polymer gels results in maintaining the original network structure, in smaller segregation compartments in polymer solutions and in smaller crystallites in the cryofixed ice matrix.

Crystallization↗
PubMed1981

Clinical and biochemical delineation of aspartyl-glycosaminuria as observed in two members of an Italian family.

Two members of a consanguineous Italian family are described with the symptoms of aspartylglycosaminuria. Both patients exhibit mental retardation, some facial dysmorphism and discrete radiological abnormalities affecting the skull and vertebrae. Peripheral blood smears revealed multivacuolated lymphocytes. Enzyme studies in leucocytes and cultured fibroblasts showed an absence of aspartylglucosaminidase activity. Urinary analysis demonstrated abnormal oligosacchariduria and aspartylglycosamine excretion. Angiokeratoma corporis diffusum was observed in one patient.

Abnormalities, Multiple↗
PubMed1979

Metabolism of 3-chloro-, 4-chloro-, and 3,5-dichlorobenzoate by a pseudomonad.

Pseudomonas sp. WR912 was isolated by continuous enrichment in three steps with 3-chloro-, 4-chloro-, and finally 3,5-dichlorobenzoate as sole source of carbon and energy. The doubling times of the pure culture with these growth substrates were 2.6, 3.3, and 5.2 h, respectively. Stoichiometric amounts of chloride were eliminated during growth. Oxygen uptake rates with chlorinated benzoates revealed low stereospecificity of the initial benzoate 1,2-dioxygenation. Dihydrodi-hydroxybenzoate dehydrogenase, catechol 1,2-dixoygenase, and muconate cycloisomerase activities were found in cell-free extracts. The ortho cleavage activity for catechols appeared to involve induction of isoenzymes with different stereospecificity towards chlorocatechols. A catabolic pathway for chlorocatechols was proposed on the basis of similarity to chlorophenoxyacetate catabolism, and cometabolism of 3,5-dimethylbenzoate by chlorobenzoate-induced cells yielded 2,5-dihydro-2,4-dimethyl-5-oxo-furan-2-acetic acid.

Biodegradation, Environmental↗
PubMed1979

[Incidence and peculiar changes in the electrocardiogram of patients after cerebrovascular insults.--Epidemiological study of 70--105-year-old people (author's transl)].

An epidemicological study of 70 to 105-year-old people revealed a frequency of cerebrovascular insults from 1,8% of living and of 23,9 respectively 34,4% of deceased men or women. As typical changes of the electrocardiogram in recent insults are to be found prolongations of the QT-interval, large and often terminal negative T-waves as well as large and high, but over the left precordium often negative U-waves.

Age Factors↗
PubMed1975

[Plasma ACTH and Nelson tumors in bilaterally adrenalectomized Cushing patients].

Bilaterally adrenalectomized patients (18) because of Cushing's syndrome were studied. 16 of these 18 persons exhibited fairly high plasma ACTH levels. Distinctly elevated plasma ACTH levels were observed in 6 of them. 5 patients of this group showed an enlarged sella and deep pigmentation of the skin. 4 of the latter group had a mucoid cell adenoma which was removed selectively. After the surgery the ACTH values were found to be within normal range without any significant endocrine dysfunction of the pituitary. A long-term ACTH survey revealed that the ACTH levels remained within the ranges of bilaterally adrenalectomized Cushing patients without concomitant enlargement of the sella or pigmentation.

Adenoma↗