[Medicine aboard cruise ships--law insurance specifics]

The booming cruise industry, associated with ships with more passengers and crew on board, results in growing medical needs for the ship doctor. The ship's doctor insurance policy includes different jurisdictions, namely national law, international law, tort law, insurance law and labor law. In addition, international agreements must be taken into account, which complicates the design of an adequate insurance policy. Equally high are the costs and defense costs for the ship's doctor in case of liability. In order to limit the liability for all parties is to ask for appropriately qualified medical staff, hired on board.

Functional desensitization of the extracellular calcium-sensing receptor is regulated via distinct mechanisms: role of G protein-coupled receptor kinases, protein kinase C and beta-arrestins

The extracellular calcium-sensing receptor (CaR) senses small fluctuations of the extracellular calcium (Ca(2+)(e)) concentration and translates them into potent changes in parathyroid hormone secretion. Dissecting the regulatory mechanisms of CaR-mediated signal transduction may provide insights into the physiology of the receptor and identify new molecules as potential drug targets for the treatment of osteoporosis and/or hyperparathyroidism. CaR can be phosphorylated by protein kinase C (PKC) and G protein-coupled receptor kinases (GRKs), and has been shown to bind to beta-arrestins, potentially contributing to desensitization of CaR, although the mechanisms by which CaR-mediated signal transduction is terminated are not known. We used a PKC phosphorylation site-deficient CaR, GRK and beta-arrestin overexpression or down-regulation to delineate CaR-mediated desensitization. Fluorescence-activated cell sorting was used to determine whether receptor internalization contributed to desensitization. Overexpression of GRK 2 or 3 reduced Ca(2+)(e)-dependent inositol phosphate accumulation by more than 70%, whereas a GRK 2 mutant deficient in G alpha(q) binding (D110A) was without major effect. Overexpression of GRK 4-6 did not reduce Ca(2+)(e)-dependent inositol phosphate accumulation. Overexpression of beta-arrestin 1 or 2 revealed a modest inhibitory effect on Ca(2+)(e)-dependent inositol phosphate production (20-30%), which was not observed for the PKC phosphorylation site-deficient CaR. Agonist-dependent receptor internalization (10-15%) did not account for the described effects. Thus, we conclude that PKC phosphorylation of CaR contributes to beta-arrestin-dependent desensitization of CaR coupling to G proteins. In contrast, GRK 2 predominantly interferes with G protein-mediated inositol-1,4,5-trisphosphate formation by binding to G alpha(q).

The human thyrotropin receptor is predominantly internalized by beta-arrestin 2

The beta-arrestin-dependent endocytosis of the beta2-adrenergic receptor (beta2AR) has been demonstrated by confocal fluorescence microscopy. Furthermore, a constitutively activated beta2AR is also constitutively desensitized and down-regulated. To clarify the function of beta-arrestin 1 or 2 for TSH receptor (TSHR) desensitization and examine whether constitutively activated TSHR mutants are internalized in a different way, we investigated the TSHR trafficking in association with beta-arrestins in cotransfection experiments in HEK 293 cells using confocal laser-scanning microscopy. We found that both beta-arrestins are able to internalize the TSHR in HEK 293 cells. However, whereas the beta-arrestin 1-mediated TSHR internalization reached its maximum 20 min after TSH stimulation, the beta-arrestin 2-mediated TSHR internalization already reached its maximum 5 min after TSH stimulation. Furthermore, an increased basal desensitization and internalization of constitutively activated TSHR mutants N670S, S505N, and F631L cotransfected with beta-arrestin 2 could not be found. After TSH stimulation the constitutively activated mutants showed the same time course for internalization as the wild-type-TSHR. In summary, contrary to data obtained for the beta2AR, the constitutive activation of the TSHR does not influence the desensitization and time course for internalization of the receptor, and in agreement with findings for the FSH and LH receptors, these results characterize the TSH receptor as a member of the class A of G protein-coupled receptors, which have a higher affinity to beta-arrestin 2 than beta-arrestin 1 and do not colocalize with beta-arrestins in endosomes.

Sialylation of human thyrotropin receptor improves and prolongs its cell-surface expression

Glycosylation of the thyrotropin receptor (TSHR) has been shown to be essential for correct protein folding and for cell-surface targeting. In a recent study, we detected increased expression of beta-galactoside alpha(2,6)-sialyltransferase (SIAT1) in toxic thyroid adenomas where gain-of-function mutations of the TSHR have been invoked as one of the major causes. To investigate the physiological meaning of these findings, we designed experiments to evaluate the consequences of sialylation for the expression of the TSHR. Hence, we investigated the effect of coexpressing the TSHR and different sialyltransferases (SIAT1, SIAT4a, and SIAT8a) for cell-surface expression of the receptor. Coexpression of each of the three SIAT isoforms and the TSHR in COS-7 cells increased TSHR expression on the cell surface in the range of 50 to 100%. Moreover, Western blot analysis with lectins specific for alpha(2,3) and alpha(2,6)-linked sialic acids and lectin-binding enzyme-linked immunosorbent assay support a direct effect on TSHR cell-surface expression mediated by sialic acid transfer to the TSHR. Finally, we treated living COS-7 cells after cotransfection of TSHR and SIAT8a with neuraminidase for 30 min to remove covalently linked sialic acid. Subsequent loss of TSHR cell-surface expression suggests that sialylation prolongs the resting time of the TSHR on the cell surface. Our data demonstrate for the first time that the transfer of sialic acid can improve and prolong cell-surface expression of a transmembrane receptor.

Gene expression analysis reveals evidence for inactivation of the TGF-β signaling cascade in autonomously functioning thyroid nodules

Molecular events that lead to the development of autonomously functioning thyroid nodules (AFTNs) are somatic mutations of the thyrotropin receptor (TSHR) in approximately 60% of the nodules and less frequently, somatic mutations in the Gsalpha protein. However, AFTNs without known mutations indicate that other causes remain to be identified. Moreover, the impact of constitutively activating TSHR mutations on the signal transduction network of the thyroid epithelial cell is unknown. We therefore investigated gene expression in 15 AFTNs and their surrounding tissue using Affymetrix GeneChips. Most prominently, data analysis revealed a changed pattern of gene expression in the TGF-beta signaling cascade and 25 differentially regulated genes in AFTNs, including thyroid peroxidase, type I iodothyronine deiodinase and sialyltransferase (SIAT) 1. Strikingly coexpression of SIAT 1 and TSHR in COS-7 cells increased TSH binding and cell surface expression of the TSHR. Moreover, differences in gene expression patterns for AFTNs with and without TSHR mutations indicate specific alterations of signal transduction in AFTNs without TSHR mutations. These results suggest that AFTNs with TSHR mutations harbor further mechanisms of forward stimulation. Furthermore, they give important leads to elucidate the molecular etiology of AFTNs without TSHR mutations.

Does a relationship exist between the quality of stress and the motivation to ingest alcohol?

Previous experimental findings on the relationship between emotional stress and motivation to ingest alcohol are contradictory. To obtain information about this relationship we tested the effects on alcohol consumption in rats subjected to two types of chronic unavoidable stressors, intermittent immobilization and social isolation, which differ in their influence on the functional state of the endogenous opioid system. To characterize the nature and magnitude of the stress induced by these stressors, we measured their effects on functional parameters which have a close relationship to the regulatory influence of endogenous opioid peptides (endogenous opioid dependence, pain sensitivity, blood pressure). Our investigations have shown that chronic intermittent immobilization, which induced development of endogenous opioid dependence, presumably due to activation of endogenous opioid systems, did not produce increased alcohol consumption. On the contrary, chronic social isolation, which did not induce development of endogenous opioid dependence, was followed by a significant increase in alcohol consumption. It is concluded that not all types of stress produce increased alcohol consumption, but that the effect on the endogenous opioid system may be a decisive factor in determining whether a stressor produces increased alcohol consumption.

[Circulatory changes in acute sauna hyperthermia after heart transplantation]

The authors report on the influence of a single sauna-stay of patients following heart transplantation (HTX) during the rehabilitation phase III. Investigations of blood pressure, heart rate, changer in hemodynamics in the small and large vessels in 8 male patients following HTX (medium age: 42 years) showed that sauna-hyperthermia is well tolerated. We watched significant decreases of blood pressure (systolic and diastolic values), an improvement of the microcirculation in the small vessels, an increase of the left ventricular ejection fraction (LVEF) and a decrease of the total peripheric vascular resistance (TPVR). Possibilities and limitations of sauna-therapy for the therapy of risk factors following HTX especially under immunosuppression are discussed. First results are demonstrated.

[Sauna therapy in coronary heart disease with hypertension after bypass operation, in heart aneurysm operation and in essential hypertension]

It is reported about the influence of the sauna therapy on blood pressure, heart frequency, peripheric hemodynamics (Xenon-133-muscle-clearance) and the reaction of the cardiac output or left ventricular ejection fraction with hypertonia patients, patients with coronary heart disease (CHD) and hypertension and after aneurysm resection after heart infarction. It was shown that sauna therapy has a positive effect on hypertonic regulations troubles. One of the reasons of lowering blood pressure is the significant improvement of the peripheral hemodynamics. Sauna therapy does not result in any improvement of the left ventricles pumping function after operation. All described groups of patients showed a good tolerance and compliance with sauna therapy.

[Autogenic training in hypertensive dysregulation after aortocoronary venous bypass operation of coronary heart disease]

The authors report on the influence of autogenous training on blood pressure at rest and under stress conditions in patients with coronary heart disease following coronary bypass operation. We investigated the influence of autogenous training on the microcirculation and the left ventricular ejection fraction (LVEF) as well. The results showed a significant decrease in blood pressure at rest and also an increase of muscle circulation F and of LVEF.

[The effect of health resort therapy on cardio-regulation following heart transplantation with special reference to CO2 balneotherapy]

It is being reported about the influence of a CO2-bathing series with 12 patients after heart-transplantation in connection with a light-motion therapy on blood pressure and haemodynamics. The comparative group was a group of 12 heart-transplantation patients of the same age without cure during the comparative time. It was shown that the balneotherapy after HTPL has positive effect on the development of the systolic blood pressure under rest and exercise. The peripheric microcirculation (musculus tibialis anterior) improved significantly. The left ventricular ejections fraction (LVEF) kept without change. Generally, the balneotherapy is well tolerated by heart-transplantation patients. There is no danger of a cardiac overcharge of the left ventricle.

Low-dosed antithyroid drug monotherapy in hyperthyroidism

In the antithyroid drug therapy, an initial treatment with low doses (10-15 mg) of methimazole (MMI) leads to satisfactory improvement in nearly all cases and even 5 mg MMI are sufficient in more than 50% of all patients. Additional intake of thyroid hormones (Th) is not necessary, if the MMI-dosage is reduced accordingly to the individual course of treatment. Consequent follow -up is to recommend anyway, particularly under the higher MMI-doses and in the first time, respectively. Consecutive measurement of total T-3 helps in assessment of euthyroidism under treatment, whereas the response to MMI is indicated more correct by total T-4. Serial determinations of serum-TSH are very helpful to decide about the cessation of treatment. If any goitre growth occurs, it seems not to be TSH-mediated in every case. Skin reactions as side-effect of high MMI-doses can be prevented by use of low doses.

ATP-dependent proton transport into vesicles of microsomal membranes of Zea mays coleoptiles

ATP-dependent proton pumps were found in the vesicles of microsomal membrane fractions of maize coleoptiles. Two membrane fractions isolated by density gradient centrifugation were identified by the aid of marker enzymes and electron microscopic analysis. Membrane fraction A largely consisted of vesicles of smooth ER and of the Golgi complex, fraction B predominantly of vesicles of plasmalemma and rough ER. The pH-indicator, neutral red, was used to measure changes in pH in the vesicles after ATP addition. Due to the binding of protonated neutral red molecules (NRH+) to negative charges of the energized membrane, a strong metachromasy of NRH+-absorption can be observed. Therefore, in order to accurately measure delta pH a pH-dependent change in absorption of neutral red covering the whole NR-spectrum was set up as difference spectra. The commonly employed method of measuring delta A of neutral red at just one wavelength (525 nm) leads to entirely incorrect results. It could be demonstrated that the ATP-dependent translocation of H+-ions into the interior of the vesicles was most efficient at pH 7. Acidification, which reaches its maximum 10--15 min after ATP addition, can be reverted by adding CCCP. An ATP-dependent proton-translocation into the vesicles of fraction B was also observed, however, the proton translocation is less than that found in fraction A in relation to the amount or protein found in each. The membrane fraction A displays a strong oxidation of NADH subsequently followed by an alkalization of the medium. This process cannot be reverted by adding CCCP. NADH oxidation at membranes of fraction A is consequently not an integral part of a redox-pump. A possible significance of the ATP-dependent proton pump in membranes of the ER and Golgi fraction of coleoptiles is discussed in connection with auxin induced elongation growth.