The esophageal mucosa and submucosa: immunohistology in GERD and Barrett's esophagus

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106843/1/nyas12241.pd

Experimental studies on barriers of the esophageal mucosa

Reflux esophagitis is the multifactorial result of the failing of protective barriers and the aggressive assault on the esophageal epithelium by gastric contents entering the esophagus. The three main lines of defense against reflux are: the antireflux barriers, the luminal acid clearance and the epithelium itself. Plasma membranes, junctional complexes, intercellular substances, as well as cell renewal are important components of the epithelial resistance. This Thesis elucidates some defense mechanisms in the epithelium utilizing the following methods: The presence of several glycoconjugates in the esophageal epithelium was determined by histochemical staining with lectins. These studies were carried out in normal, healthy mammals, as well as in rabbits with acute mucosal damage caused by the perfusion of the esophagus with pepsin/HCl. In parallel, early acid induced changes of epithelial integrity were studied by measuring the transmural electrical resistance of the esophagus, using cable analysis. A chronic reflux esophagitis model was developed in cats by transection of the muscle fibers in the region of the gastroesophageal junction, thereby disabling the lower esophageal sphincter. The resulting changes on the esophageal epithelium were studied by light microscopy. Finally, by continuous labeling of dividing cells with 3H-thymidine, cell turnover times of the esophageal epithelium were determined in normal rats, as well as in rats with hypergastrinemia for up to 9 days. This condition was achieved by continuous subcutaneous infusion of gastrin-17 or by inhibition of gastric acid secretion with omeprazole. The investigations demonstrate that there are several types of glycoconjugates in the intercellular spaces of the epithelium with heaviest accumulation in the stratum superficiale. Perfusion with pepsin/HCl reduces, not only the staining intensity of some of these glycoconjugates, but also the transmural electrical resistance. In these studies of acute damage sucrose octasulfate provided some protection. Myotomy of the gastroesophageal sphincter leads to a decrease in lower esophageal sphincter pressure, chronic reflux esophagitis with inflammation, basal cell hyperplasia and erosions, resembling reflux esophagitis in man. The cell turnover time in the epithelium of normal rat esophagus averages 10.4 days; hypergastrinemia shortens this by about 10%; in these rats the esophageal epithelium becomes almost 20% thinner than in the controls

Are laboratory parameter (biomarker) values similar to the healthy volunteer reference range in all patient populations?

David A Brott,1 Michael J Goodman,1 Richard P Hermann,1 Michael Merz,2 Roser Calvo,1 Nadereh Poorkhalkali,3 Alexandre Kiazand1 1Patient Safety, Safety Science, AstraZeneca Pharmaceuticals, Gaithersburg, MD, USA; 2Patient Safety, Safety Science, AstraZeneca Pharmaceuticals, Webel, Germany; 3Patient Safety, Safety Science, AstraZeneca Pharmaceuticals, Gothenburg, Sweden Background: Liver biomarkers alanine aminotransferase (ALT) and bilirubin in patients with hepatitis are above the healthy volunteer reference range (HVRR) at baseline (prior to receiving the clinical trial medication). Discussions continue as how to best distinguish drug-induced liver injury in patients with abnormal baseline values participating in clinical trials. This study investigated if other baseline routine clinical safety biomarkers (lab parameters) are different from the HVRR. Materials and methods: Clinical trial data (TransCelerate dataset) from placebo and standard of care treated patients were compared to the HVRR using a 10% threshold above or below the HVRR to classify a lab parameter in a patient population as potentially different from the HVRR at baseline. The TransCelerate dataset, batch 4, contained data from patients with Alzheimer’s, asthma, COPD, cardiovascular disease, diabetes, hidradenitis, hypercholesterolemia, rheumatoid arthritis, schizophrenia, stroke, and ulcerative colitis. A subset of the 200 biomarkers in TransCelerate were evaluated in this pilot: glucose, platelet count, neutrophil count, ALT, aspartate aminotransferase (AST), and bilirubin. Results: Glucose was potentially higher than the HVRR in patients with diabetes, COPD, cardiovascular disease, hypercholesterolemia, and schizophrenia. At least one or more of the hematology and hepatic biomarkers were different from the HVRR in at least one patient population, except bilirubin. All the patient populations, except Alzheimer’s and asthma, had at least one biomarker that was higher than the HVRR. Summary: The routine biomarkers evaluated in this pilot study demonstrated that not all lab parameters in patient populations are similar to the HVRR. Further efforts are needed to determine which biomarkers are different from the HVRR and how to evaluate the biomarkers in patient populations for detecting drug-induced altered lab values in clinical trials. Keywords: patient populations, reference range, healthy volunteer, biomarker

Expression of GABA\u3csub\u3eB\u3c/sub\u3e Receptors in Magnocellular Neurosecretory Cells of Male, Virgin Female and Lactating Rats

GABA is one of the key neurotransmitters that regulate the firing activity of neurones in the supraoptic (SON) and paraventricular (PVN) nuclei. In the present study, we used immunohistochemical techniques to study the distribution and subcellular localisation of metabotropic GABAB receptors in magnocellular neurones in the SON and PVN. Robust GABAB receptor immunoreactivity (GABABR; both subunit 1 and subunit 2 of the heterodimer), was observed in the SON and PVN. At the light microcope level, GABABR immonoreactivity displayed a clustered pattern localised both intracytoplasmically and at the plasma membrane. Densitometry analysis indicated that GABABR immunoreactivity was significantly more intense in vasopressin cells than in oxytocin cells, both in male, virgin female and lactating rats, and was denser in males than in virgin females. Light and electron microscope studies indicated that cytoplasmic GABABR was localised in various organelles, including the Golgi, early endosomes and lysosomes, suggesting the cycling of the receptor within the endocytic and trafficking pathways. Some smaller clusters at the level of the cell plasma membrane were apposed to glutamic acid decarboxylase 67 immunoreactive boutons, and appeared to be colocalised with gephyrin, a constituent protein of the postsynaptic density at inhibitory synapses. The presence of GABABR immunoreactivity at synaptic and extrasynaptic sites was supported by electron microscopy. These results provide anatomical evidence for the expression of postsynaptic GABAB receptors in magnocellular neurosecretory cells