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R Fricke

Publications and source records attributed to R Fricke.

At least 19 recordsLinked to original sources
PubMed2005

Patterns of hormone replacement therapy in a population-based cohort of postmenopausal German women. Changes after HERS II and WHI.

In July 2002, data from the Women's Health Initiative (WHI) trial provided strong evidence for an increased risk of cardiovascular disease with use of combined estrogen plus progestogen in postmenopausal women. These unexpected results triggered a large and ongoing discussion about the role of hormone replacement therapy (HRT). We investigated the frequency of HRT before and after the publications of the WHI trial and the Heart and Estrogen/Progestin Replacement Study II (HERS II) in a population-based random sample of German women aged 45 - 65 years. A total of 8380 women completed a questionnaire on menopausal status, hysterectomy and HRT. 75 % were postmenopausal. Mean age was 56.1 years; mean age of natural menopause 49.9 years; mean duration of postmenopause was 11 years; 27 % of the women had undergone hysterectomy. The percentage of current HRT users dropped by 16 % (35.4 % to 29.8 %, p = 0.004), past users increased from 19.8 % to 23.5 % (p = 0.03). Among current HRT users, the share of combined conjugated estrogen/progestogen decreased by 41 % (p = 0.008). We observed a decreased prevalence of HRT among German women 7 months after publication of the HERS II and WHI results. The decline was, however less pronounced than reported from other countries. The use of conjugated estrogen/gestagen combinations declined disproportionately compared to other formulations.

Aged↗
PubMed2002

Peripheral arterial tonometry for the diagnosis of obstructive sleep apnea.

Sleep related breathing disorders have been recognized as a risk factor for cardiovascular disorders. Peripheral arterial tonometry (PAT) allows to monitor vasoconstriction on the finger continuously and non-invasively. We investigated whether the rapid changes of autonomous function can be assessed by PAT. In 21 patients with obstructive sleep apnea and arterial hypertension we recorded PAT in parallel to cardiorespiratory polysomnography and invasive arterial blood pressure. The correlation between periodic PAT attenuations and the total number of apneas (r = 0.656, p < 0.01) and the total number of cortical arousal (r = 0.583, p < 0.01) were significant. The PAT signal cannot substitute blood pressure but allows a good recognition of apneas and subcortical arousal and gives additional information on changes of sympathetic and parasympathetic tone during sleep.

Adult↗
PubMed1999

[Psychological health at school entrance].

INTRODUCTION: The rate of psychiatric disorders in childhood and adolescence was investigated in numerous studies and was found to be between 10% and 18%, boys having more problems to tackle than girls. These studies often concern school-age children, but it is sure that psychiatric disorders already occur in early childhood. In the present study, mental health was assessed in children of Jena, who were starting with school. A comparison with methodologically similar studies in Heidelberg and Cologne was possible. METHODS: The study was conducted in cooperation with the health department of Jena. Parents had to fill in the CBCL (Child Behaviour Checklist), which assesses behavioural disturbances and social competence. Participation was voluntary and anonymous. RESULTS AND DISCUSSION: From the total population of 1039 children 749 (72.0%) checklists were filled in by the parents. 674 (64.9%) checklists were completely filled in and included in the study. 86 out of 674 (64.9%) of the children had a psychiatric disorder, boys (13.4%) more often than girls (12.2%), especially in the scales "Externalizing disorders", "delinquent behaviour", "aggressive behaviour" and "attention deficit disorders". Children coming from certain areas (Lobeda, Winzerla) had not have more disturbances than children from the central part of the city. Only 8.1% of the parents of children with psychiatric disorders recognise such problems, and only 16.3% of these children had a visit with a physician or psychologist within the last year. This leads to the conclusion, that the sensitivity for psychiatric disorders of children must be improved.

Child↗
PubMed1996

Determination of metalloproteinases, plasminogen-activators and their inhibitors in the synovial fluids of patients with rheumatoid arthritis during chemical synoviorthesis.

The concentrations of matrix metalloproteinase-1 (MMP-1), matrix metalloproteinase-8 (MMP-8), matrix metalloproteinase-9 (MMP-9), lactoferrin and urokinase plasminogen activator (uPA), tissue-type plasminogen activator (tPA) and the inhibitors, tissue inhibitor of metalloproteinase-1 (TIMP-1), plasminogen activator inhibitor-1 (PAI-1), plasminogen activator inhibitor (PAI-2), and alpha2-macroglobulin in the synovial fluids of patients with rheumatoid arthritis was determined before and during chemical synoviorthesis with a sodium salt of the fatty acids from cod-liver oil (Varicocid). Synovial fluids were obtained before treatment from 37 patients with rheumatoid arthritis and, in most cases, at 8 and 24 h after injection of the agent. Well-established ELISAs were used to determine the amounts of all proteins. All patients with rheumatoid arthritis revealed very high levels of metalloproteinases (about 1-15 mu g/ml) in their synovial fluids. During the inflammation inducing treatment the granulocyte enzymes increased. In contrast to this, the level of MMP-1 decreased. All granulocyte-derived enzymes were strongly correlated with each other, whereas their dependence on the granulocyte count was only weak. uPA and PAI-2 showed good correlations with the granulocytes-derived enzymes, but were also only weakly correlating with the cell counts. t-PA was not detected by the ELISA used. The proteases, MMP-8, MMP-9 and uPA were increased 8 h after the treatment, whereas the specific inhibitors TIMP-1, PAI-1 and PAI-2 showed significant changes only 24 h after the injection. Matrix metalloproteinases are important factors in the pathogenesis of rheumatoid arthritis. The inflammatory activity in the joint could be better correlated to the granulocyte enzymes than to the granulocyte counts. The levels of uPA and PAI-2 are also parallel to the granulocyte enzyme levels and might underly the same regulatory mechanism.

Adult↗
PubMed1996

Initial binding of the elongation factor Tu.GTP.aminoacyl-tRNA complex preceding codon recognition on the ribosome.

The first step in the sequence of interactions between the ribosome and the complex of elongation factor Tu (EF-Tu), GTP, and aminoacyl-tRNA, which eventually leads to A site-bound aminoacyl-tRNA, is the codon-independent formation of an initial complex. We have characterized the initial binding and the resulting complex by time-resolved (stopped-flow) and steady-state fluorescence measurements using several fluorescent tRNA derivatives. The complex is labile, with rate constants of 6 x 10(7) M-1 s-1 and 24 s-1 (20 degrees C, 10 mM Mg2+) for binding and dissociation, respectively. Both thermodynamic and activation parameters of initial binding were determined, and five Mg2+ ions were estimated to participate in the interaction. While a cognate ternary complex proceeds form initial binding through codon recognition to rapid GTP hydrolysis, the rate constant of GTP hydrolysis in the non-cognate complex is 4 orders of magnitude lower, despite the rapid formation of the initial complex in both cases. Hence, the ribosome-induced GTP hydrolysis by EF-Tu is strongly affected by the presence of the tRNA. This suggests that codon-anticodon recognition, which takes place after the formation of the initial binding complex, provides a specific signal that triggers fast GTP hydrolysis by EF-Tu on the ribosome.

Codon↗
PubMed1995

Codon-dependent conformational change of elongation factor Tu preceding GTP hydrolysis on the ribosome.

The mechanisms by which elongation factor Tu (EF-Tu) promotes the binding of aminoacyl-tRNA to the A site of the ribosome and, in particular, how GTP hydrolysis by EF-Tu is triggered on the ribosome, are not understood. We report steady-state and time-resolved fluorescence measurements, performed in the Escherichia coli system, in which the interaction of the complex EF-Tu.GTP.Phe-tRNAPhe with the ribosomal A site is monitored by the fluorescence changes of either mant-dGTP [3'-O-(N-methylanthraniloyl)-2-deoxyguanosine triphosphate], replacing GTP in the complex, or of wybutine in the anticodon loop of the tRNA. Additionally, GTP hydrolysis is measured by the quench-flow technique. We find that codon-anticodon interaction induces a rapid rearrangement within the G domain of EF-Tu around the bound nucleotide, which is followed by GTP hydrolysis at an approximately 1.5-fold lower rate. In the presence of kirromycin, the activated conformation of EF-Tu appears to be frozen. The steps following GTP hydrolysis--the switch of EF-Tu to the GDP-bound conformation, the release of aminoacyl-tRNA from EF-Tu to the A site, and the dissociation of EF-Tu-GDP from the ribosome--which are altogether suppressed by kirromycin, are not distinguished kinetically. The results suggest that codon recognition by the ternary complex on the ribosome initiates a series of structural rearrangements resulting in a conformational change of EF-Tu, possibly involving the effector region, which, in turn, triggers GTP hydrolysis.

Anticodon↗
PubMed1994

Transient conformational states of aminoacyl-tRNA during ribosome binding catalyzed by elongation factor Tu.

Conformational transitions of Phe-tRNA(Phe) that take place during elongation factor Tu (EF-Tu)-dependent binding to the A site of Escherichia coli ribosomes were followed by transient fluorescence measurements. The fluorescence signal of proflavin replacing dihydrouracil at position 16 or 17 in yeast tRNA(Phe) was utilized to monitor changes of the conformation of the D loop. The ternary complex EF-Tu.GTP.Phe-TRNA(Phe)(Pf16/17) was purified by gel filtration. Upon binding of the complex to the A site of poly(U)-programmed, P-site-blocked ribosomes, the fluorescence changes in several steps. First, the rapid formation of an initial complex gives rise to a small fluorescence increase. Subsequent codon-anticodon recognition leads to a conformational rearrangement of the D loop of the tRNA that is reflected in a major fluorescence increase. Fluorescence-quenching data indicate an unfolding of the D loop in this state. The latter conformational state is short-lived, and the aminoacyl-tRNA refolds during the following rearrangement that occurs after GTP hydrolysis and accompanies the release of the aminoacyl-tRNA from EF-Tu.GDP and/or its accommodation in the A site. Further experiments show that the status of the P site influences the binding to the A site in that the two rearrangement steps are slowed down when the P site is unoccupied and even more so when it is occupied with the near-cognate tRNA(Leu2). In contrast, the occupancy of the E site has no influence on A-site binding, and vice versa, thus excluding any coupling between the two sites.

Anti-Bacterial Agents↗
PubMed1982

[Animal experimental model of lung contusion].

Introduction and discussion of an experimental animal model to the representation of an isolated lung contusion in rats. The damage is realized by means of pressure waves. There can be observed distinct lung contusions - even unilateral - without chest wall lesions or extrathoracal injuries. One can also recognize temporal lapses of different intensity of the trauma. The model appears suitable to the presentation of a possible independent pathogenesis of the lung contusion.

Animals↗
PubMed1981

[Gastric carcinoma with retroperitoneal symptoms (a contribution to differential diagnosis)].

Report on a 28-year-old patient, whose metastasizing carcinoma of the stomach could be ascertained only autoptically after a 1-year course of the disease. The intraoperative findings had supposed a primary disease of the retroperitoneal space. On the basis of this observation the differential diagnosis of retroperitoneal coparticipation of primary pathological processes of the abdominal cavity is discussed.

Adult↗
PubMed1981

[Experimental animal studies on lung contusion].

Isolating lung contusions were represented by means of animal experiments in rats. The mechanism of the trauma was a bounce against the thorax wall with a steel cylinder. Macroscopic pulmonary alterations, lung weights, the frequency of secondary injuries as well as the mortality rate are the parameters of the lesion. The lung alterations shows communities with human lung contusions. The model is suitable for the specification of histological and morphological alterations and for the pathogenesis of lung contusions as well as for the quest of diagnostic parameters. The intensity of the lung contusion is limited by initial rupture of vessels. To the test of clinical therapy and for the release of limited lung contusions there are required models with other mechanisms of trauma.

Animals↗
PubMed1978

An autoradiographic study of the commissural and ipsilateral hippocampo-dentate projections in the adult rat.

The distribution of the associational and commissural afferents to the inner one-fourth of the molecular layer of the dentate gyrus of the rat, has been studied autoradiographically following small injections of 3H-proline into the hilar region of the dentate (from which both groups of afferents arise). Different patterns of axonal labeling are observed after injections into the temporal (i.e., caudal), middle, or septal (rostral) thirds of the hippocampus. Thus after temporal injections labeled commissural and associational afferents are found only in the caudal third of the dentate gyrus, and the grain densities observed on the two sides are markedly asymmetrical around the short, or transverse, axis of the dentate. On the other hand, injections into the middle third of the hippocampus lead to extensive labeling of the commissural and associational afferents throughout the rostral two-thirds of the dentate gyrus, and their distribution, as judged by grain density estimates, is symmetrical on the two sides. Septal injections label fibers over the rostral half of the dentate, and again the labeling pattern on the two sides is asymmetrical (but in the reverse pattern from that seen after temporal injections). These distinctive patterns in the distribution of the two classes of afferents can generally be accounted for on the following assumptions: (1) the commissural and associational afferents share a common cytochemical specificity; (2) they compete with each other for the limited number of synaptic sites available upon the proximal portions of the granule cells: (3) the granule cells are generated along two distinct morphogenetic gradients:from the temporal to the septal pole of the dentate gyrus, and from the tip of its dorsal (or external) to the tip of its ventral (internal) blade; and (4) the first fibers to arrive monopolize the majority of the available synaptic sites, and those that reach their target field later, synapse predominantly upon the last-formed granule cell dendrites. To this extent our findings are consonant with the "temporal hypothesis" first formulated by Gottlieb and Cowan ('72). However, to account for the restricted distribution of afferents from the temporal part of the hippocampus, it is necessary to further postulate that there is some degree of topographic (or region-to-region) specificity in the ipsilateral and contralateral hippocampo-dentate projections.

Animals↗
PubMed1977

An autoradiographic study of the development of the entorhinal and commissural afferents to the dentate gyrus of the rat.

The development of the entorhinal, ipsilateral associational, and commissural afferents to the dentate gyrus have been studied autoradiographically, following the injection of small amounts of tritiated proline into the medial and lateral parts of the entorhinal cortex, and into fields CA3c and CA4 of the hippocampus, in a series of rats, on the third, sixth, and twelfth postnatal days. Clear labeling of the entorhinal afferents were found at the third postnatal day, and from the earliest stage studied the afferents from the two parts of the entorhinal cortex appear to be spatially segregated within the stratum moleculare of the dentate gyrus: the fibers from the lateral entorhinal area occupying the outermost one-third, or so, of this stratum, while those from the medial entorhinal cortex occupy its middle zone. The ipsilateral hippocampo-dentate associational pathway is present at the third postnatal day, but the commissural projection (which shares with it the inner part of the stratum moleculare) could not be labeled until the sixth postnatal day. By the twelfth day the characteristic adult pattern of distribution of the terminals of the two hippocampo-dentate pathways is established. Although this pattern is best accounted for on the basis of a temporal competition for the available synaptic sites on the proximal parts of the dendrites of the granule cells, the spatial segregation of these two fiber systems from those arising in the entorhinal cortex, is probably due to the selective fasciculation of fibers in each group of afferents and to their early cytochemical specificity.

Afferent Pathways↗