Impairment of contractile response to carbachol and muscarinic receptor coupling in gastric antral smooth muscle cells isolated from diabetic streptozotocin-treated rats and db/db mice

This work explored the role of the cholinergic pathway, assessed at a post-synaptic level by the use of isolated smooth muscle cells, in the impairment of antral motility associated with diabetic gastroparesis.Contractile response to carbachol — but not to erythyromycin, a motilin receptor agonist — was abolished in antral smooth muscle cells isolated from (i) rats previously rendered diabetic by a single i.v. dose of streptozotocin (STZ, 60 mg/kg) and (ii) db/db spontaneously diabetic mice. Insulin treatment of STZ-rats was able to prevent the impairment of the carbachol contractile response, but not to reverse it once established. In STZ-rats, impairment of contractile response was not associated with a change in density of [3H]-N-methyl-scopolamine ([³H]-NMS) binding sites ( 1.5 fmol/mg protein). Displacement curve of the [³H]-NMS binding by carbachol was shifted to the right in diabetic rats as compared to controls. The addition of GTP--S induced a shift to the right of the displacement curve in control but not in diabetic animals.These results strongly suggest that diabetes is associated with an early and specific alteration of the muscarinic control of contraction of antral smooth muscles at a post-synaptic level, associated with an alteration of the GTP-binding proteins coupled to muscarinic receptors.     

Long-Term Dosimetry of Solar UV Radiation in Antarctica with Spores of Bacillus subtilis

The main objective was to assess the influence of the seasonal stratospheric ozone depletion on the UV climate in Antarctica by using a biological test system. This method is based on the UV sensitivity of a DNA repair-deficient strain of Bacillus subtilis (TKJ 6321). In our field experiment, dried layers of B. subtilis spores on quartz discs were exposed in different seasons in an exposure box open to solar radiation at the German Antarctic Georg von Neumayer Station (70°37′S, 8°22′W). The UV-induced loss of the colony-forming ability was chosen as the biological end point and taken as a measure for the absorbed biologically harmful UV radiation. Inactivation constants were calculated from the resulting dose-response curves. The results of field experiments performed in different seasons indicate a strongly season-dependent trend of the daily UV-B level. Exposures performed at extremely depleted ozone concentrations (October 1990) gave higher biologically harmful UV-B levels than expected from the calculated season-dependent trend, which was determined at normal ozone values. These values were similar to values which were measured during the Antarctic summer, indicating that the depleted ozone column thickness has an extreme influence on the biologically harmful UV climate on ground.     

Conformation of 6,7-dimethyl-8-ribityllumazine bound to β-subunits of heavy riboflavin synthase: Transferred nuclear overhauser effect (TrNOE) studies employing ω1-13C-filtered NOESY including a novel technique for zero quantum suppression

Summary The -subunits of heavy riboflavin synthase catalyze the formation of 6,7-dimethyl-8-ribityllumazine. The interaction of the¹³C-labelled enzyme product with isolated -subunits was studied by transfer NOE measurements using ₁=¹³C-filtered NOESY and¹³C-¹H-relayed NOESY. The advantages of these techniques are the removal of residual enzyme signals, the simplification of zero quantum suppression, and the improvement of water suppression which enabled the semiquantitative study of¹H-¹H distances of the ligand in the bound state. The preferred conformation of the ribityl side chain was calculated on the basis of the measured distances.     

“As du Coeur” study: a randomized controlled trial on quality of life impact and cost effectiveness of a physical activity program in patients with cardiovascular disease

Background

Physical activity programs (PAP) in patients with cardiovascular disease require evidence of cost-utility. To assess improvement in health-related quality of life (QoL) and reduction of health care consumption of patients following PAP, a randomized trial was used.

Methods

Patients from a health insurance company who had experienced coronary artery disease or moderate heart failure were invited to participate (N?=?1891). Positive responders (N?=?50) were randomly assigned to a progressively autonomous physical activity (PAPA) program or to a standard supervised physical activity (SPA) program. The SPA group had two supervised sessions per week over 5?months. PAPA group had one session per week and support to aid habit formation (written tips, exercise program, phone call). To measure health-related quality of life EQ-5D utility score were used, before intervention, 6?months (T6) and 1 year later. Health care costs were provided from reimbursement databases.

Results

Mobility, usual activities and discomfort improved significantly in both group (T6). One year later, EQ-5D utility score was improved in the PAPA group only. Total health care consumption in the intervention group decreased, from a mean of 4097 euros per year before intervention to 2877 euros per year after (p?=?0.05), compared to a health care consumption of 4087 euros and 4180 euros per year, in the total population of patients (N?=?1891) from the health insurance company. The incremental cost effectiveness ratio was 10,928 euros per QALYs.

Conclusion

A physical activity program is cost-effective in providing a better quality of life and reducing health care consumption in cardiovascular patients.

Trial registration

ISRCTN77313697, retrospectively registered on 20 November 2015.

     

Convergent selection pressures drive the evolution of rhodopsin kinetics at high altitudes via nonparallel mechanisms

Convergent evolution in response to similar selective pressures is a well‐known phenomenon in evolutionary biology. Less well understood is how selection drives convergence in protein function, and the underlying mechanisms by which this can be achieved. Here, we investigate functional convergence in the visual system of two distantly related lineages of high‐altitude adapted Andean and Himalayan catfishes. Statistical analyses revealed in the two high‐altitude lineages, a parallel acceleration of evolutionary rates in rhodopsin, the dim‐light visual pigment. However, the elevated rates were found to be accompanied by substitutions at different sites in the protein. Experiments substituting Andean‐ or Himalayan‐specific residues significantly accelerated the kinetic rates of rhodopsin, destabilizing the ligand‐bound forms. As found in cold‐adapted enzymes, this phenotype likely compensates for a cold‐induced decrease in kinetic rates, properties of rhodopsin mediating rod sensitivity and visual performance. Our study suggests that molecular convergence in protein function can be driven by parallel shifts in evolutionary rates but via nonparallel molecular mechanisms. Signatures of natural selection may therefore be a powerful guide for identifying complex instances of functional convergence across a wider range of protein systems.     

Desipramine Elicits the Expression of Opiate Receptors and Sulfogalactosylceramide Synthesis in Rat C6 Glioma Cells

In the course of our studies on lipidoses induced by amphiphilic drugs, we have investigated the ef- of desipramine, a tricyclic antidepressant, on glial cells in culture. We noted that the addition of desipramine to the culture medium of C6 glioma cells resulted in the modification of the lipid profile of the cell membranes. Of particular interest was the presence, in the desipramine-treated cells, of an additional lipid comigrating on thin layer chromatography with sulfogalactosylceramide (S-GalCer). Addition of radiolabelled sulfuric acid in the culture medium of the desipramine-treated cells resulted in the incorporation of [35S]sulfate in the newly synthesized lipid. Furthermore, this lipid was localized selectively by indirect immunofluorescence using a specific rabbit anti-S-GalCer antibody on the cell surface of desipramine-treated, but not control, C6 cells. Desipramine also increased the activity of 3'-phosphoadenosine-5'-phosphosulfate sulfotransferase (the enzyme responsible for the synthesis of S-GalCer). Since it has been suggested that S-GalCer may be involved in opiate receptors, we looked for opiate binding sites on C6 glioma cells after exposure to desipramine. We found that dihydromorphine was able to bind to the desipramine-treated C6 cell membrane. The binding of [3H]dihydromorphine (180 fmol/mg protein) was stereospecific and had a KD of 30-60 nM. Furthermore, morphine reduced both the basal and isoproterenol-stimulated cyclic AMP levels of the desipramine-treated C6 cells. This effect was blocked by naloxone. In these respects, the opiate binding sites induced after treatment of C6 glioma cells with desipramine fulfill the requirements of a true opiate receptor.     

Cholecystokinin varies in the posterior pituitary and external median eminence of the rat according to factors affecting vasopressin and oxytocin

Using radioimmunoassay (RIA), the content of gastrin-cholecystokinin family peptide immunoreactivity (G-CCK-IR), in the posterointermediate lobe (PIL) of the rat pituitary, has been determined in several experimental conditions. G-CCK-IR levels are significantly higher in males than in females. Salt loading induces a significant decrease of G-CCK-IR in animals of either sex. In males, G-CCK-IR levels are lower than controls 21 days after either castration or daily subcutaneous oestradiol injections. Using immunocytochemistry, G-CCK-IR disappears from the external median eminence 21 days after adrenalectomy. Our results show that, in addition to sex difference, factors affecting the vasopressin and/or oxytocin levels in the posterior pituitary and external median eminence also affect G-CCK-IR in the same regions. Cholecystokinin may therefore be of importance in functions related to these hormones.     

Cardiac arrhythmias that masquerade as epilepsy.

Over six months 10 patients, representing 20% of those referred to a neurological department with possible idiopathic epilepsy, were subsequently considered to have cardiac arrhythmias that caused or significantly contributed to their symptoms. In some cases relevant arrhythmias were shown only after prolonged electrocardiographic monitoring. Although several theoretical and practical factors need to be assessed when considering the cardiac basis for cerebral disturbances, unsuspected cardiac arrhythmias may underlie "epilepsy" in many patients.     

Molecular genetic analysis of the 17p11.2 region in patients with hereditary neuropathy with liability to pressure palsies (HNPP)

Hereditary neuropathy with liability to pressure palsies (HNPP) is in most cases associated with an interstitial deletion of the same 1.5-Mb region at 17p11.2 that is duplicated in Charcot-Marie-Tooth type 1A (CMT1A) patients. Unequal crossing-over following misalignment at flanking repeat sequences (CMT1A-REP), either leads to tandem duplication in CMT1A patients or deletion in HNPP patients. With the use of polymorphic DNA markers located within the CMT1A/HNPP duplication/deletion region we detected the HNPP deletion in 16 unrelated HNPP patients, 11 of Belgian and 5 of French origin. In all cases, the 1.5-Mb size of the HNPP deletion was confirmed by EcoRI dosage analysis using a CMT1A-REP probe. In the 16 HNPP patients, the same 370/320-kb EagI deletion-junction fragments were detected with pulsed field gel electrophoresis (PFGE), while in CMT1A patients, a 150-kb EagI duplication-junction fragment was seen. Thus, PFGE analysis of EagI-digested DNA with a CMT1A-REP probe allows direct detection of the HNPP deletion or the CMT1A duplication for DNA diagnostic purposes.