A novel role for the metabotropic glutamate receptor-7: modulation of faecal water content and colonic electrolyte transport in the mouse

Background and purpose:

Increasing evidence implicates metabotropic glutamate receptor mGlu₇ in the pathophysiology of stress-related disorders such as depression and anxiety. Mood disorders are frequently associated with gastrointestinal (GI) dysfunction; however, the role of mGlu₇ receptors outside the CNS is unknown. This present study investigated the expression and possible functional role of mGlu₇ receptors in the mouse colon.

Experimental approach:

Expression of mGlu₇ receptor mRNA and protein was studied in mouse colon by in situ hybridization and Western blotting. Effects of the selective mGlu₇ receptor agonist AMN082 on defecation and faecal parameters were studied in an isolation-induced stress model. AMN082 effects on ion transport and neuronal intracellular signalling were examined via Ussing chambers and calcium imaging.

Key results:

mGlu₇ receptor mRNA and protein were highly expressed in colon mucosa. Stress-induced faecal output was unaffected by AMN082, although faecal water content was increased. In mucosa/submucosa preparations, 100 nM and 1 µM AMN082 increased bethanechol-induced changes in short-circuit current in the Ussing chamber. This was sensitive to tetrodotoxin. Also, 100 nM AMN082 significantly increased calcium signalling in a subset of submucosal neurons.

Conclusions and implications:

Activating mGlu₇ receptors increased colonic secretory function in vivo and ex vivo. In a group of submucosal neurons, AMN082 strongly induced calcium signalling and the presence of submucosal nerves was required for the AMN082-dependent increase in secretion. These data suggest that targeting mGlu₇ receptors may be useful in the treatment of central components of stress disorders and also stress-associated GI dysfunction such as diarrhoea or constipation.     

Comparative performances of enzyme-linked immunosorbent, western blot, and polymerase chain reaction assays for human T-lymphotropic virus type II infection that is endemic among Indians of the Gran Chaco region of South America

BACKGROUND : Human T-cell lymphoma/leukemia viruses types I and II (HTLV- I and HTLV-II) are related exogenous human retroviruses. The former is definitely pathogenic while disease association with the latter is unclear. There are two subtypes of HTLV-II, A and B. Currently, enzyme- linked immunosorbent assays (ELISAs) based on HTLV-I antigens are used to screen for the presence of HTLV-I and -II antibodies. Confirmation and subtyping are accomplished by Western blot (WB) or ELISAs based on HTLV-I whole viral antigens and/or HTLV-I and HTLV-IIA peptides. The sensitivity and specificity of these serologic assays were compared to those of HTLV-I and-II-specific polymerase chain reaction (PCR) assays in tests on samples from Indians from South America in whom the HTLV- IIB subtype is endemic. STUDY DESIGN AND METHODS : Sera from 246 Gran Chaco Indians were evaluated for HTLV antibodies with the use of four ELISAs (Retrotek HTLV-I; Cambridge Biotech rgp21 enhanced HTLV-I/II; Vironostika HTLV-I/II; and Select HTLV-I/II), and a WB assay. Peripheral blood leukocyte DNA from each Indian was analyzed for HTLV-I or HTLV-II pol DNA via PCR. Fifteen of the PCR-positive samples were further subtyped via cloning and sequencing and/or oligomer restriction. RESULTS : Ninety-seven samples (39%) were positive for HTLV- II by serologic and/or PCR assays. All 15 positive DNA samples that were further analyzed were of the HTLV-IIB subtype and were clustered as a highly conserved phylogenetic group. Comparative analyses indicate that the sensitivity and specificity of the various assays were: PCR, 97 and 100 percent; Retrotek, 70 and 91 percent; Cambridge Biotech, 74 and 96 percent; Vironostika, 73 and 99 percent; Select 72 and 98 percent; and WB, 70 and 100 percent. CONCLUSION : The sensitivities of the tested HTLV serologic assays were comparable. However, the specificity of the Retrotek ELISA was significantly lower than that of the others. When positive, the subtyping assays were very specific. However, PCR assays would seem preferable or to be a necessary adjunct for the sensitive detection of HTLV-IIB infection.     

Interest of co-cultures for embryos obtained by in-vitro fertilization: a French collaborative study

Co-cultures of human embryos, particularly with Vero cells, are used by several French groups, mainly in cases of successive failures of implantation. In most cases co-culture is continued until the blastocyst stage, expanded if possible. A total of 1603 co-cultures have been performed by 11 groups over a 2-year period. Of these, 41.8% of cleaved eggs (day 2) reached the blastocyst stage at day 5 or day 6. The mean pregnancy rate and implantation rate per transfer were 32.9 and 24.8% respectively, which represented a significant improvement compared to the transfer of 2 day old embryos. The rate of multiple pregnancies remained high (29.1%), which implies that there should be transfer of not more than two blastocysts. The rate of anomalies perceived at birth or in utero was not different from the rate observed in the general population, taking account of the maternal age.      

Unsubstituted hydrolyzed waxy maize as a potential agent for centrifugal leukacytapheresis

In order to determine whether newer, possibly safer erythrocyte sedimenting agents could be used during centrifugal leukacytapheresis, we tested seven varieties of plant starch. Only waxy maize prepared by partial acid hydrolysis appeared suitable, and it was tested extensively on an analytical device developed especially for testing erythrocyte sedimentation under the conditions of residence time, force, and sedimenting agent concentration used in a cell separator. This species of waxy maize, however, was not quite as effective a sedimenting agent when compared to hydroxyethyl starch (HES 450/0.70) under the test conditions used. Although chromatographic analysis showed the average molecular weights of the unsubstituted waxy maize were considerably higher than those of HES 450/0.70, degradation of waxy maize to smaller molecular weight fragments occurred more rapidly. The rapid degradation of this material may offer significant advantages during centrifugal leukacytapheresis procedures, but additional studies of its storage stability are needed.     

Obstructed calycocystostomy site in association with a transplanted kidney: percutaneous management

We have used advanced endourologic techniques in the treatment of an obstructed lower-pole calycocystostomy site. The unusual clinical course that led to this problem and the interventional treatment used are discussed.     

Migraine trigger factors in a non-clinical Mexican-American population in San Diego county: implications for etiology

We conducted an investigation of migraine headache in a general population of Mexican-Americans living in San Diego county. Specific headache triggers were reported and analyzed, the most frequently reported for females with migraine being missing meals (58.9%), weather changes (54.4%), menstruation (53.6%), post-crisis letdown (52.7%), and fatigue (51.8%). The most frequently reported trigger factors for migraines reported by males were fatigue (58.8%), sleep (as a precipitating factor) (56.3%), post-crisis letdown (41.2%), and weather changes (37.5%). Trigger factors were further evaluated using stratification by presence or absence of Raynaud's phenomenon (RP), menstrual migraine, family history of migraine, and by migraine type. Odds ratios and 95% confidence intervals were calculated. These results suggest that subjects with migraine and RP (perhaps indicative of a systematic vascular tone disorder) and those with menstrual migraine (indicative of sensitivity to hormonal changes) may overall be more sensitive to certain environmental stimuli, particularly those involving change in the internal environment.