Development of a sandwich ELISA to detect circulating, soluble IRAP as a potential disease biomarker

There is growing interest in the use of the enzyme, insulin regulated aminopeptidase (IRAP), as a biomarker for conditions such as cardio-metabolic diseases and ischemic stroke, with upregulation in its tissue expression in these conditions. However, quantification of circulating IRAP has been hampered by difficulties in detecting release of the truncated, soluble form of this enzyme into the blood stream. The current study aimed to develop a sandwich ELISA using novel antibodies directed towards the soluble portion of IRAP (sIRAP), to improve accuracy in detection and quantification of low levels of sIRAP in plasma. A series of novel anti-IRAP antibodies were developed and found to be highly specific for sIRAP in Western blots. A sandwich ELISA was then optimised using two distinct antibody combinations to detect sIRAP in the low nanogram range (16-500 ng/ml) with a sensitivity of 9 ng/ml and intra-assay variability < 10%. Importantly, the clinical validity of the ELISA was verified by the detection of significant increases in the levels of sIRAP throughout gestation in plasma samples from pregnant women. The specific and sensitive sandwich ELISA described in this study has the potential to advance the development of IRAP as a biomarker for certain diseases.

Chemoselective Methionine Labelling of Recombinant Trastuzumab Shows High In Vitro and In Vivo Tumour Targeting

A highly effective 2-step system for site-specific antibody modification and conjugation of the monoclonal antibody Herceptin (commercially available under Trastuzumab) in a cysteine-independent manner was used to generate labelled antibodies for in vivo imaging. The first step contains redox-activated chemical tagging (ReACT) of thioethers via engineered methionine residues to introduce specific alkyne moieties, thereby offering a novel easy way to fundamentally change the process of antibody bioconjugation. The second step involves modification of the introduced alkyne via azide-alkyne cycloaddition 'click' conjugation. The versatility of this 2-step approach is demonstrated here by the selective incorporation of a fluorescent dye but can also be applied to a wide variety of different conjugation partners depending on the desired application in a facile manner. Methionine-modified antibodies were characterised in vitro, and the diagnostic potential of the most promising variant was further analysed in an in vivo xenograft animal model using a fluorescence imaging modality. This study demonstrates how methionine-mediated antibody conjugation offers an orthogonal and versatile route to the generation of tailored antibody conjugates with in vivo applicability.

Deletion of hepatic carbohydrate response element binding protein (ChREBP) impairs glucose homeostasis and hepatic insulin sensitivity in mice

OBJECTIVE

Carbohydrate response element binding protein (ChREBP) is a transcription factor that responds to glucose and activates genes involved in the glycolytic and lipogenic pathways. Recent studies have linked adipose ChREBP to insulin sensitivity in mice. However, while ChREBP is most highly expressed in the liver, the effect of hepatic ChREBP on insulin sensitivity remains unknown. To clarify the importance of hepatic ChREBP on glucose homeostasis, we have generated a knockout mouse model that lacks this protein specifically in the liver (Liver-ChREBP KO).

METHODS

Using Liver-ChREBP KO mice, we investigated whether hepatic ChREBP deletion influences insulin sensitivity, glucose homeostasis and the development of hepatic steatosis utilizing various dietary stressors. Furthermore, we determined gene expression changes in response to fasted and fed states in liver, white, and brown adipose tissues.

RESULTS

Liver-ChREBP KO mice had impaired insulin sensitivity as indicated by reduced glucose infusion to maintain euglycemia during hyperinsulinemic-euglycemic clamps on both chow (25% lower) and high-fat diet (33% lower) (p < 0.05). This corresponded with attenuated suppression of hepatic glucose production. Although Liver-ChREBP KO mice were protected against carbohydrate-induced hepatic steatosis, they displayed worsened glucose tolerance. Liver-ChREBP KO mice did not show the expected gene expression changes in liver in response to fasted and fed states. Interestingly, hepatic ChREBP deletion also resulted in gene expression changes in white and brown adipose tissues, suggesting inter-tissue communication. This included an almost complete abolition of BAT ChREBPβ induction in the fed state (0.15-fold) (p = 0.015) along with reduced lipogenic genes. In contrast, WAT showed inappropriate increases in lipogenic genes in the fasted state along with increased PEPCK1 in both fasted (3.4-fold) and fed (5.1-fold) states (p < 0.0001).

CONCLUSIONS

Overall, hepatic ChREBP is protective in regards to hepatic insulin sensitivity and whole body glucose homeostasis. Hepatic ChREBP action can influence other peripheral tissues and is likely essential in coordinating the body's response to different feeding states.

Peptides specific for Mycobacterium avium subspecies paratuberculosis infection: diagnostic potential

Mycobacterium avium subspecies paratuberculosis (Map) is the causative agent of Johne's disease (JD). Current serological diagnostic tests for JD are limited by their sensitivity when used in sub-clinical stages of the disease. Our objective was to identify peptides that mimic diagnostically important Map epitopes that might be incorporated into a new-generation JD diagnostic. Four peptides were isolated from a phage-displayed random peptide library by screening on antibodies derived from Map-infected goats. The peptides were recognised by antibodies from Map-infected goats but not by antibodies from uninfected goats. The peptides elicited immune responses in rabbits, which reacted strongly with bona fide Map antigens proving the peptides were true epitope mimics. To assess the diagnostic value a panel of goat sera was screened for reactivity's with peptides. The peptides were recognised by antibodies from a proportion of goats infected with Map compared with control animals with a diagnostic specificity of 100% and the sensitivity ranged from 50 to 75%. Combinations of any two peptides improved sensitivity 62.5-87.5% and 100% sensitivity was achieved with three of the four peptides in combination. These data suggest peptides representing diagnostically important Map epitopes could be incorporated into a sensitive diagnostic test.

A single dose of intravenous esomeprazole decreases gastric secretion in healthy volunteers

BACKGROUND

Data suggest that esomeprazole decreases gastric secretion.

AIMS

To assess the effect of a single i.v. esomeprazole dose on gastric secretion volume 3 h after drug administration, as a primary endpoint, and to evaluate, as secondary endpoints, the reduction 1 and 5 h after dosing; time when the gastric pH was <2.5 and esomeprazole's safety.

METHODS

In all, 23 healthy Helicobacter pylori-negative volunteers (10 men, 13 women, mean age 28.2 +/- 6) participated in this single-centre, randomized, double-blind, placebo-controlled, 2-way, single-dose cross-over study. In different sessions, volunteers received i.v. either esomeprazole 40 mg or placebo. An inserted double-lumen nasogastric tube perfused and aspirated gastric liquid. Mechanical fractioned aspiration measured secretion volume; aliquot spectrophotometry assessed gastric secretion volume lost to the duodenum.

RESULTS

Three hours post-i.v. esomeprazole, average gastric secretion decreased by 77.6% (vs. baseline) compared to placebo. Values 1 and 5 h after dosing were 73.5% and 74.5%. Five hours after esomeprazole, the gastric pH was <2.5 3.9% of the time and 73.3% after placebo (P < 0.002). Esomeprazole was well-tolerated. No serious adverse events occurred.

CONCLUSIONS

Intravenous esomeprazole decreases gastric secretions. The potential clinical impact in averting bronchoaspiration during anaesthesia induction and in intensive care patients should be investigated in further studies.

[Long-term treatment of patients with symptomatic gastroesophageal reflux disease comparing costs and efficacy over 6 months of treatment with Nexium On-Demand Treatment or Nexium continuous treatment. An open, randomised multi-center study]

This open, randomized study (ONE: On-demand Nexium Evaluation) compared the two long-term management options with esomeprazole 20 mg--continuous daily or on-demand treatment--in endoscopically uninvestigated patients seeking primary care for symptoms suggestive of gastroesophageal reflux disease (GERD) who demonstrated complete relief of symptoms after four weeks of initial treatment with esomeprazole 40 mg. In total 1904 patients were randomized. During 26 weeks 913 patients received continuous daily therapy with esomeprazole 20 mg, once daily, while 991 patients were treated with esomeprazole 20 mg on-demand. The continuous therapy offered slightly better relief of the symptom heartburn, however esomeprazole 20 mg taken on-demand was associated with lower direct medical costs. Esomeprazole was generally well tolerated.

[Laparoscopic colon reposition and closure of the diaphragm in secondary incarcerated pre-existent diaphragmatic hernia]

We report on a 28-year-old patient, who acquired a left diaphragmatic hernia after suffering a motorcycle accident seven years ago. The diaphragmatic hernia was not diagnosed at that time. After a laparoscopic cholecystectomy performed for acute cholcystitis, there was herniation and secondary incarceration of a bowel segment into the preexistent diaphragmatic hernia. We describe laparoscopic surgical repositioning of the bowel segment and closure of the diaphragmatic defect.

[Laparoscopic excision of a urachus umbilical fistula]

We report on a 24-year-old female patient with a chronic secretion from an umbilical fistula. We describe the laparoscopic removal of the fistula using two 5-mm and two 10-mm ports.

[Laparoscopic endoscopic pre-peritoneal combined hernia operation in incarcerated indirect inguinal hernia]

We report on a 73-year-old patient with an incarcerated right sided groin hernia. First the incarcerated small bowel was gently retracted laparoscopically; then using the extraperitoneal endoscopic approach the hernial sack was redused and a 15/13 cm prosthesis (polypropylene mesh) brought in appropriate position and fixed with endo-staples. Prior to closing the trocar-incisions the vitality of the small bowel was checked once again laparoscopically.

[Inguinal hernia as a sequela of disordered bladder emptying?]

We examined 56 patients with hernias and 49 patients with other diseases prior to operation. They were all above 50 years of age. The urological screening examination included the patients history of the frequency of urination during night and day time, dysuria, the common risk factors (smoking, coughing, obstipation), obesity, a sonographic measurement of the prostate diameters, a sonographic evaluation of residual urine and the determination of the urinary flow rate. None of the above parameters showed a significant difference between the two groups. Surprisingly more than 60% of all men showed a pathological voiding function (either residual urine and/or a pathological flow rate). Our conclusions are: 1. Patients with inguinal hernias do not show a greater incidence of pathological bladder function than patients of the control group. The benign prostatic hypertrophy as a risk factor for the development of inguinal hernias is most questionable. 2. Because the results showed no significant difference between the two groups, a determination of residual urine prior to operation is not necessary. 3. More than 60% of the men above 50 years showed a pathological voiding function. We recommend a urological screening test for all men above 50 years of age during hospitalisation.