Helicobacter pylori, gastric pathology, and histopathological diagnosis

Structural analogues of ZAPA, Z-3-[(aminoiminomethyl)thio]prop-2-enoic acid, an isothiouronium analogue of GABA, are potent GABAA agonists as seen in the isolated guinea-pig ileum and in the facilitation of [3H]diazepam binding to rat brain membranes. Compounds with guanidino or amidine groups replacing the amino functionality of GABA were also found to be active. The highest activity was displayed by the isothiouronium salts in which the conformational flexibility of the molecule is restricted by a Z-substituted carbon-carbon double bond. A series of bis-isothiouronium compounds was prepared from aliphatic alpha, omega-bis-thioureas as mixtures of E and Z adducts. Maximum GABAA agonist activity for this series was found with a C6-C8 carbon chain, and the results were consistent with an interaction at the GABAA receptor with only one end of the molecule, rather than the more potent effect expected of a molecule bridging two active sites. GABAA antagonist/partial agonist activity was observed on the guinea pig isolated ileum for a number of different analogue types, with the most potent being bis-isothiouronium derivatives. None of the substituted derivatives of ZAPA was as active as ZAPA itself, and maximum GABAA activity was found in the n-pentyl and n-hexyl analogues.     

Analysis of continuous beams on discrete elastic supports by the five moment equation

The analysis of continuous beams on discrete elastic supports is a complex problem frequently encountered in structural engineering. In structures of this type, the supports displace in direct proportion to the support reactions. These support displacements result in moment redistribution in the beam. The methods in current use for solving this type of problem arc generally complex and in most cases are developed for analysis of more complicated structures.This paper illustrates a technique for computer analysis of continuous beams on discrete elastic supports by the five moment equation. The objective is to present a viable example for electronic computation consistent with the nature of the problem, and which will tend to contribute to the basic understanding of the use of computers in reducing the amount of computation.The five moment equation is an extension of the familiar three moment equation and results in the same simple form of analysis. The solution of the five moment equation for the analysis of continuous beams on elastic supports permits direct determination of the redundant moments at the supports. The result of this simplified form provides practicing engineers with an efficient analysis easily handled on small office computers. For the student of civil engineering, the method illustrated will significantly contribute to development of effective early progress of programming skills.     

Prevalence of upper gastrointestinal lesions and Helicobacter pylori infection in Crohn's disease

Crohn's disease can affect the upper gut with reported variable frequency, although concurrent Helicobacter pylori infection has been reported to be low. We prospectively investigated the prevalence of esophageal, gastric, and duodenal lesions and Helicobacter pylori infection in 67 Crohn's disease, 41 ulcerative colitis patients, and 43 controls. Symptoms, esophagogastroduodenoscopy, and multiple biopsies were performed on all patients consecutively. Endoscopic lesions were found in 63% of Crohn's disease patients, with a Helicobacter pylori prevalence of 28%. Granulomas were found in three patients. Twenty-two percent of the ulcerative colitis patients had lesions, with a 29% prevalence of Helicobacter pylori infection. Half of the controls had pathological endoscopy, and Helicobacter pylori was positive in 40% of the cases. Subjective symptoms did not predict the presence of endoscopic lesions or Helicobacter pylori infection in inflammatory bowel disease patients. Chronic gastritis and duodenitis are common in Crohn's disease patients, and the majority are not associated with Helicobacter pylori infection.     

Frame synchronization for coded systems over AWGN channels

For the additive white Gaussian noise channel, we consider the problem of frame synchronization for coded systems. We present an algorithm that takes advantage of soft information provided by a soft decoder to produce an enhanced estimate of the frame boundary. To reduce complexity, a companion algorithm is introduced that is a hybrid of the optimal uncoded frame synchronizer introduced by Massey and the list synchronizer introduced by Robertson. The high-complexity coded maximum-likelihood frame synchronizer used by Robertson will accordingly be replaced by our algorithm, which operates on decoder-provided soft decisions. The algorithm begins by obtaining a list of high-probability starting positions via the log-likelihood function of the optimal uncoded frame synchronizer. Then, a test /spl delta/ is used to decide if the decision of the optimal uncoded frame synchronizer is sufficient, or whether list synchronization is required. If the test chooses in favor of using the optimal uncoded synchronizer, the estimate is obtained with relative ease. Otherwise, list synchronization is performed, and statistics provided by the decoder are used to resolve the frame boundary. Monte Carlo simulations demonstrate that the frame-synchronization-error rate (the probability of the synchronizer making an error) achieves the lower bound for signal-to-noise ratio values exceeding 1 dB.