Identification and characterization of aquaporin-2 water channel mutations causing nephrogenic diabetes insipidus with partial vasopressin response

Congenital nephrogenic diabetes insipidus (NDI) is a rare disease caused most often by mutations in the vasopressin V2 receptor (AVPR2). We studied a family which included a female patient with NDI with symptoms dating from infancy. The patient responded to large doses of desmopressin (dDAVP) which decreased urine volume from 10 to 4 I/day. Neither the parents nor the three sisters were polyuric. The patient was found to be a compound heterozygote for two novel recessive point mutations in the aquaporin-2 (AQP2) gene: L22V in exon 1 and C181W in exon 3. Residue Cys181 in AQP2 is the site for inhibition of water permeation by mercurial compounds and is located near to the NPA motif conserved in all aquaporins. Osmotic water permeability (Pf) in Xenopus oocytes injected with cRNA encoding C181W-AQP2 was not increased over water control, while expression of L22V cRNA increased the Pf to approximately 60% of that for wild-type AQP2. Co-injection of the mutant cRNAs with the wild-type cRNA did not affect the function of the wild-type AQP2. Immunolocalization of AQP2-transfected CHO cells showed that the C181W mutant had an endoplasmic reticulum-like intracellular distribution, whereas L22V and wild-type AQP2 showed endosome and plasma membrane staining. Water permeability assays showed a high Pf in cells expressing wild-type and L22V AQP2. This study indicates that AQP2 mutations can confer partially responsive NDI.      

Loperamide

In castor oil challenged rats, low doses of loperamide inhibit diarrhea and normalize intestinal propulsion. Unlike other opioids, loperamide is devoid of central opiate-like effects, including blockade of intestinal propulsion, up to the highest subtoxic oral dose. Nevertheless, the antidiarrheal action of loperamide can be considered to be -opiate receptor mediated, only a fewin vitro effects at rather high concentrations being not naloxone-reversible. There is little evidence that interactions with intestinal opiate receptors directly change epithelial cell function. When secretory stimuli increase mucosal tension, however, loperamide may reverse the elevated hydrostatic tissue pressure that opposes normal absorption. This antisecretory effect at the mucosal level is accompanied by motor effects when loperamide reaches the myenteric -opiate receptors. At therapeutic doses for the treatment of acute diarrhea, it is likely that the mucosal effect prevails.     

Protein biomarkers for breast cancer prevention.

Protein biomarkers suitable for the prevention of breast cancer must be extremely sensitive, easily detectable and highly correlated with the disease. They should be expressed in the reversible phase of carcinogenesis. Among the large number of candidate tumour-associated proteins, those related to the oestrogen/chorionic gonadotropin/insulin pathway seem to be of most interest because these can be causally implicated. They presumably are the first to express differently and are open to hormonal treatments. The biomarkers that give information on membrane receptor-modulated signal transduction should be considered as well. Up to now, only tamoxifen has shown some preventive activity, suggesting that the oestrogen pathway is useful indeed. Fenretinide and recombinant human chorionic gonatotropin (hCG) are also promising. But the financial requirements and the very long assessment periods largely prevent current research. This is precisely why we badly need to give priority to molecular biology research, in particular in the protein compartment There is widespread belief that advanced proteomics together with increased informatics can provide specific combinations of disease-related expression profiles that could identify high-risk groups with much more reliability and allow us to monitor preventive strategies.     

Use of Antibiotic Prophylaxis in Ear Surgery

A prospective, double-blind, randomized, placebo-controlled study was performed to evaluate the effect of antibiotic prophylaxis in ear surgery. The present study reports on the results of 750 patients, half of whom received cefuroxime for 1 day, the other half, placebo. All postoperative infections occurring within 2 weeks after the intervention were recorded, together with several preoperative and perioperative parameters. It is concluded that exploratory tympanoplasties (including stapedotomy) and “dry perforation” tympanoplasties should be considered “clean” operations according to the American National Research Council and do not benefit from antibiotic prophylaxis. On the other hand, tympanoplasties performed on draining ears and on ears with cholesteatoma should be considered “dirty” operations for which antibiotic prophylaxis may decrease the postoperative infection rate by factor 3. All postoperative infections healed without sequels under proper treatment, except for three that resulted in graft necrosis-one in the placebo group and two in the cefuroxime group. In consequence, prophylaxis may not be mandatory in the dirty group, although the authors advocate its use for the sake of patient and surgeon comfort.     

Validity of the recording of meningococcal disease according to various sources of information

A study was made in Belgium in order to assess the completeness and specificity of the recording of meningococcal disease by routine sources of information. Ninety-three cases identified in a hospital survey were linked with those recorded in mortality statistics, in the notification of communicable diseases, and by the National Reference Laboratory for meningococci. Statistics based on mortality data appeared to be of low validity. The overall completeness of recording was 44% for the notification of communicable disease, and 40% for the reference laboratory. When these two sources were used for surveillance, the completeness of case-finding increased to 56%. When the analysis was restricted to bacteriologically-confirmed cases, the completeness of recording was 62% for the notification system, 70% for the laboratory, and 84% for both sources. The surveillance of communicable diseases should rely on various sources of information. Laboratory data should be systematically used in order to improve both the completeness of recording and the specificity of case-ascertainment.     

Effects of a motilin receptor agonist (ABT-229) on upper gastrointestinal symptoms in type 1 diabetes mellitus: a randomised, double blind, placebo controlled trial

INTRODUCTION: Erythromycin, a motilin agonist, is a potent prokinetic. ABT-229 is a specific motilin agonist that dose dependently accelerates gastric emptying. Dyspepsia and gastroparesis are common problems in type 1 diabetes mellitus. We aimed to evaluate the efficacy of ABT-229 in symptomatic diabetic patients with and without delayed gastric emptying. METHODS: Patients with type 1 diabetes and postprandial symptoms were randomised (n=270). Based on a validated C(13) octanoic acid breath test, patients were assigned to either the delayed or normal gastric emptying strata. Patients received one of four doses of ABT-229 (1.25, 2.5, 5, or 10 mg twice daily before breakfast and dinner) or placebo for four weeks following a two week baseline. A self report questionnaire measured symptoms on visual analogue scales; the primary outcome was assessment of change in the total upper abdominal symptom severity score (range 0-800 mm) from baseline to the final visit. RESULTS: The treatment arms were similar regarding baseline characteristics. There was symptom improvement on placebo and a similar level of improvement on active therapy for the upper abdominal discomfort severity score (mean change from baseline -169, -101, -155, -143, and -138 mm for placebo, and 1.25, 2.5, 5, and 10 mg ABT-229, respectively, at four weeks by intent to treat). The results were not significantly different in those with and without delayed gastric emptying. The severity of bloating, postprandial nausea, epigastric discomfort, heartburn, and acid regurgitation worsened dose dependently in a greater number of patients receiving ABT-229 than placebo. Overall, 63% of patients on placebo reported a good or excellent global response, and this was not different from the active treatment arms. CONCLUSIONS: The motilin agonist ABT-229 was not efficacious in the relief of postprandial symptoms in diabetes mellitus in the presence or absence of delayed gastric emptying.     

ATG16L1 and NOD2 polymorphisms enhance phagocytosis in monocytes of Crohn’s disease patients

AIM:To investigate if the presence of relevant genetic polymorphisms has effect on the effectual clearance of bacteria by monocytes and granulocytes in patients with Crohn’s disease(CD).METHODS:In this study,we assessed the differential responses in phagocytosis by measuring the phagocytic activity and the percentage of active phagocytic monocytes and granulocytes in inflammatory bowel disease patients as well as healthy controls.As both autophagy related like 1(ATG16L1)and immunityrelated guanosine triphosphatase gene are autophagy genes associated with CD and more recently nucleo-tide-binding ligomerization domain-containing protein2(NOD2)has been identified as a potent inducer of autophagy we genotyped the patients for these variants and correlated this to the phagocytic reaction.The genotyping was done with restriction fragment length polymorphisms analysis and the phagocytosis was determined with the pHrodo?Escherichia coli Bioparticles Phagocytosis kit for flowcytometry.RESULTS:In this study,we demonstrate that analysis of the monocyte and granulocyte populations of patients with CD and ulcerative colitis showed a comparable phagocytic activity(ratio of mean fluorescence intensity)between the patient groups and the healthy controls.CD patients show a significantly higher phagocytic capacity(ratio mean percentage of phagocytic cells)compared to healthy controls(51.91%±2.85%vs 37.67%±7.06%,P=0.05).The extend of disease was not of influence.However,variants of ATG16L1(WT:2.03±0.19 vs homozygoot variant:4.38±0.37,P<0.009)as well as NOD2(C-ins)(heterozygous variant:42.08±2.94 vs homozygous variant:75.58±4.34(P=0.05)are associated with the phagocytic activity in patients with CD.CONCLUSION:Monocytes of CD patients show enhanced phagocytosis associated with the presence of ATG16L1 and NOD2 variants.This could be part of the pathophysiological mechanism resulting in the disease.