Isocitrate Dehydrogenase of Helicobacter pylori Potentially Induces Humoral Immune Response in Subjects with Peptic Ulcer Disease and Gastritis

Background. H. pylori causes gastritis and peptic ulcers and is a risk factor for the development of gastric carcinoma. Many of the proteins such as urease, porins, flagellins and toxins such as lipo-polysaccharides have been identified as potential virulence factors which induce proinflammatory reaction. We report immunogenic potentials of isocitrate dehydrogenase (ICD), an important house keeping protein of H. pylori. Methodology/Principal Findings. Amino acid sequences of H. pylori ICD were subjected to in silico analysis for regions with predictably high antigenic indexes. Also, computational modelling of the H. pylori ICD as juxtaposed to the E. coli ICD was carried out to determine levels of structure similarity and the availability of surface exposed motifs, if any. The icd gene was cloned, expressed and purified to a very high homogeneity. Humoral response directed against H. pylori ICD was detected through an enzyme linked immunosorbent assay (ELISA) in 82 human subjects comprising of 58 patients with H. pylori associated gastritis or ulcer disease and 24 asymptomatic healthy controls. The H. pylori ICD elicited potentially high humoral immune response and revealed high antibody titers in sera corresponding to endoscopically-confirmed gastritis and ulcer disease subjects. However, urea-breath-test negative healthy control samples and asymptomatic control samples did not reveal any detectable immune responses. The ELISA for proinflammatory cytokine IL-8 did not exhibit any significant proinflammatory activity of ICD. Conclusions/Significance. ICD of H. pylori is an immunogen which interacts with the host immune system subsequent to a possible autolytic-release and thereby significantly elicits humoral responses in individuals with invasive H. pylori infection. However, ICD could not significantly stimulate IL8 induction in a cultured macrophage cell line (THP1) and therefore, may not be a notable proinflammatory agent

In vivo and in silico determination of essential genes of Campylobacter jejuni

<p>Abstract</p> <p>Background</p> <p>In the United Kingdom, the thermophilic <it>Campylobacter </it>species <it>C. jejuni </it>and <it>C. coli </it>are the most frequent causes of food-borne gastroenteritis in humans. While campylobacteriosis is usually a relatively mild infection, it has a significant public health and economic impact, and possible complications include reactive arthritis and the autoimmune diseases Guillain-Barré syndrome. The rapid developments in "omics" technologies have resulted in the availability of diverse datasets allowing predictions of metabolism and physiology of pathogenic micro-organisms. When combined, these datasets may allow for the identification of potential weaknesses that can be used for development of new antimicrobials to reduce or eliminate <it>C. jejuni </it>and <it>C. coli </it>from the food chain.</p> <p>Results</p> <p>A metabolic model of <it>C. jejuni </it>was constructed using the annotation of the NCTC 11168 genome sequence, a published model of the related bacterium <it>Helicobacter pylori</it>, and extensive literature mining. Using this model, we have used <it>in silico </it>Flux Balance Analysis (FBA) to determine key metabolic routes that are essential for generating energy and biomass, thus creating a list of genes potentially essential for growth under laboratory conditions. To complement this <it>in silico </it>approach, candidate essential genes have been determined using a whole genome transposon mutagenesis method. FBA and transposon mutagenesis (both this study and a published study) predict a similar number of essential genes (around 200). The analysis of the intersection between the three approaches highlights the shikimate pathway where genes are predicted to be essential by one or more method, and tend to be network hubs, based on a previously published <it>Campylobacter </it>protein-protein interaction network, and could therefore be targets for novel antimicrobial therapy.</p> <p>Conclusions</p> <p>We have constructed the first curated metabolic model for the food-borne pathogen <it>Campylobacter jejuni </it>and have presented the resulting metabolic insights. We have shown that the combination of <it>in silico </it>and <it>in vivo </it>approaches could point to non-redundant, indispensable genes associated with the well characterised shikimate pathway, and also genes of unknown function specific to <it>C. jejuni</it>, which are all potential novel <it>Campylobacter </it>intervention targets.</p

Value of beat-to-beat blood pressure changes, detected by pulse transit time, in the management of the obstructive sleep apnoea/hypopnoea syndrome.

Two important aspects of a respiratory sleep study are a measure of inspiratory effort and an estimate of the number of arousals. These can be derived from an indirect estimate of beat-to-beat blood pressure (BP), pulse transit time (PTT). This study investigated the reproducibility of inspiratory BP falls (reflecting inspiratory effort), and BP arousals derived from PTT, and the contribution they could make to the management of the obstructive sleep apnoea/hypopnoea syndrome (OSAHS). Overnight PTT was recorded at home in 40 patients being investigated for OSAHS, and a second PTT recording was made in the sleep laboratory with full polysomnography. Patients were divided into three groups according to the severity of their sleep disorder, and a third PTT recording was made at home in 13 patients subsequently established on nasal continuous positive airway pressure (CPAP). The reproducibility between the home and laboratory studies was reasonable (r=0.87 for inspiratory BP falls, r=0.81 for BP arousals). Both derivatives showed a clear progression through the three patient groups, which returned to normal on treatment. The differences between the groups were significant (p&lt;0.001 for inspiratory BP falls, p=0.0014 for BP arousals). Receiver operator characteristic curves, used to compare polysomnography variables and PTT variables, confirmed that the PTT variables were as good as apnoea-hypopnoea index (AHI), &gt;4% arterial oxygen saturation dip rate and electroencephalography micro-arousals at dividing patients into two groups, either requiring nasal CPAP or not requiring CPAP. Pulse transit time can provide a noninvasive estimate of inspiratory effort and a measure of arousals that together document disease severity and response to treatment and may be useful in managing obstructive sleep apnoea/hypopnoea syndrome

Relationship between autonomic arousals, EEG arousals, respiratory events and subjective sleepiness in patients undergoing investigation for obstructive sleep apnoea

Daytime hypersomnolence is an important symptom of the sleep apnoea/hypopnoea syndrome and the most compelling reason for treatment. Measuring sleep fragmentation is thus critical in a respiratory sleep study. Sleep fragmentation can be estimated from respiratory events (apnoeas, hypopnoeas, dips in oxygen saturation), EEG arousals, and autonomic changes (heart rate and blood pressure rises). We have compared these different approaches in 40 patients having polysomnography for possible sleep apnoea, as well as their correlation with subjective sleepiness (Epworth Sleepiness Score, ESS). Respiratory signals were scored for apnoeas / hypopnoeas (AHI) and dips in arterial oxygen saturation of &gt;4% (Dip rate); EEG was scored by the American Sleep Disorders Association criteria for 3 second arousals (ASDA); autonomic measures were heart rate rises of &gt; 10 bpm (HR) and indirect blood pressure rises (pulse transit time, PTT, Clin Sci 1994;87:269). The number of events/hour was used to calculate the correlation between each of these and their correlation with ESS (P &lt; 0.05 for all correlations displayed). Data analysis is not yet complete, n &gt; 21 for all correlations. HR ASDA AHI Dip rate ESS PTT r = 0.87 r = 0.91 r = 0.72 r = 0.87 r = 0.38 HR r = 0.73 r = 0.53 r = 0.80 ASDA r = 0.92 r = 0.92 r = 0.39 AHI r = 0.88 Dip rate r = 0.49 Respiratory events, EEG arousals and autonomic arousals are closely correlated. Dip rate is the best predictor of ESS. PTT measured blood pressure rises may provide a useful automated alternative to manual scoring of EEG arousals as an index of sleep fragmentation

Automatic nasal continuous positive airway pressure titration in the laboratory, patient outcomes

Manual titration of nasal continuous positive airway pressure (NCPAP) treatment for obstructive sleep apnoea (OSA) is time consuming and expensive. There are now 'intelligent' NCPAP machines that try to find the ideal pressure for a patient by monitoring some combination of apnoeas, hypopnoeas, inspiratory flow limitation and snoring. Although these machines usually find similar pressures to skilled technicians, it is not clear if their use in the sleep laboratory influences subsequent acceptance by patients. 122 patients with OSA undergoing a trial of NCPAP were randomly allocated to either manual or automatic (Horizon, DeVilbiss) titration of pressure during their first night on NCPAP in a hospital sleep laboratory. The primary outcome (available on 112 patients) was the acceptance of NCPAP or otherwise, six weeks following the initial titration night. Baseline indicators of severity were compared in the groups, as were the pressures selected and the patients' subsequent improvement in sleepiness. Initial OSA severity was not significantly different in the two groups. The mean NCPAP pressures (cmH2O) in the two groups were similar (manual 8.7 SD2.5, automatic 8.2 SD2.1). The % of patients successfully established on CPAP at six weeks was 64% and 73% for the manual and automatic groups respectively: 13% versus 2% had given up completely (manual and automatic respectively, P&lt;0.05) and there were about equal numbers (23% versus 25%) in each group who were still undecided. The improvement in the Epworth sleepiness score was similar in the two groups. The substitution of automatic NCPAP titration instead of a manual titration during the first night of NCPAP in patients with OSA does not reduce the numbers accepting the treatment at six weeks, and may slightly improve it. This has important cost saving potential

New approaches to monitoring sleep-related breathing disorders.

Conventional approaches to the analysis of sleep and sleep apnea do not describe all of the critical events that result from upper airway narrowing during sleep. The hypersomnolence that drives treatment is mainly due to microarousals, but these are poorly documented with conventional epoch-based sleep staging. The counting of apneas and hypopneas also fails to document other equally important events, such as the arousals due to increased respiratory effort in response to partial upper airway narrowing that may not cause significant hypopnea, hypoxemia, or even snoring. Modifications of conventional polysomnography, such as microarousal detection and analysis of the ribcage/abdominal paradox, may be an improvement. However, no system has been shown to be better than any other at identifying the critical events that produce symptoms of sleep-related breathing disorders, and thus be likely to respond to effective treatment. The time is right to explore innovative ways to characterize sleep-related breathing disorders, such as those derived from the cardiovascular change related to upper airway obstruction and arousal, without the shackles of conventional polysomnography. New monitoring techniques need to identify patients with events that will respond to treatment, not mimic the flawed gold standard of polysomnography

Use of the Epworth Sleepiness Scale to demonstrate response to treatment with nasal continuous positive airways pressure in patients with obstructive sleep apnoea.

The Epworth Sleepiness Scale (ESS) was used to measure the degree of daytime sleepiness in two groups of patients with obstructive sleep apnoea (OSA), before and after treatment with nasal continuous positive airways pressure (CPAP). One group (50 patients) were assessed after 2 months CPAP treatment after which the mean ESS fell from 16.4 [standard error of mean (SEM) 0.52] to 7.0 (SEM 0.56). A second group (25 patients) were assessed after 1 yr of treatment: a similar fall in mean ESS was seen from 15.2 (SEM 1.13) before treatment to 6.0 (SEM 0.72). These results imply that the ESS can be used clinically to demonstrate the response of daytime sleepiness in OSA to treatment with CPAP, and that the fall in ESS seen after 2 months is sustained after 1 yr of treatment. It is also possible that this approach could be used to monitor the progress of treatment with CPAP

Automatic nasal continuous positive airway pressure titration in the laboratory: patient outcomes.

BACKGROUND: Manual titration of nasal continuous positive airway pressure (NCPAP) treatment for obstructive sleep apnoea (OSA) is time consuming and expensive. There are now "intelligent" NCPAP machines that try to find the ideal pressure for a patient by monitoring a combination of apnoeas, hypopnoeas, inspiratory flow limitation, and snoring. Although these machines usually find similar pressures to skilled technicians, it is not clear if their use in the sleep laboratory influences subsequent acceptance by patients. This study addresses this question. METHODS: One hundred and twenty two patients undergoing a trial of NCPAP were randomly allocated to either manual or automatic (Horizon, DeVilbiss) titration of pressure during their first night on NCPAP in a hospital sleep laboratory. The primary outcome (available on 112 patients) was the acceptance of NCPAP or otherwise six weeks following the initial titration night. Baseline indicators of severity were compared between the groups, as were the pressures selected and the subsequent improvement in the sleepiness of the patients. RESULTS: The initial severity of OSA was not significantly different in the two groups and the mean (SD) NCPAP pressures were similar (manual 8.7 (2.5) cm H2O, automatic 8.2 (2.1) cm H2O). The percentage of patients successfully established on CPAP at six weeks was 64% and 73% for the manual and automatic groups, respectively; 13% and 2%, respectively, in the manual and automatic groups had given up completely (p &lt; 0.05), and there were about equal numbers (23% versus 25%) in the two groups who were still undecided. CONCLUSIONS: The substitution of automatic NCPAP titration for manual titration during the first night of NCPAP in patients with OSA does not reduce the number accepting the treatment at six weeks and may slightly improve it. This has important cost saving potential

Use of pulse transit time as a measure of inspiratory effort in patients with obstructive sleep apnoea.

Pulse transit time (PTT) is the time taken for the arterial pulse pressure wave to travel from the aortic valve to a peripheral site. For convenience, it is usually measured from the R wave on the electrocardiogram to the pulse wave arrival at the finger. Pulse transit time is inversely proportional to blood pressure, and the falls in blood pressure which occur with inspiration (pulsus paradoxus) correspond to rises (lengthening) in pulse transit time. In awake normal subjects, the size of these inspiratory rises in pulse transit time correlate well with the degree of inspiratory effort. The aim of this study was to investigate whether inspiratory rises in pulse transit time could provide a quantitative measure of inspiratory effort in patients with obstructive sleep apnoea. Eight patients with obstructive sleep apnoea, attending the laboratory for institution of nasal continuous positive airway pressure, took part in the study. Once asleep, airway pressure was varied between optimal treatment level and minimum pressure, to produce a range of inspiratory efforts whilst continuous recordings of oesophageal pressure and pulse transit time were made. There was an excellent correlation between the size of the swings in oesophageal pressure and the size of the swings in pulse transit time (mean r = 0.94). Pulse transit time may, therefore, provide a clinically useful noninvasive and quantitative measure of inspiratory effort in patients with sleep-related breathing disorders