CD47 interactions with exportin-1 limit the targeting of m7G-modified RNAs to extracellular vesicles

CD47 is a marker of self and a signaling receptor for thrombospondin-1 that is also a component of extracellular vesicles (EVs) released by various cell types. Previous studies identified CD47-dependent functional effects of T cell EVs on target cells, mediated by delivery of their RNA contents, and enrichment of specific subsets of coding and noncoding RNAs in CD47+ EVs. Mass spectrometry was employed here to identify potential mechanisms by which CD47 regulates the trafficking of specific RNAs to EVs. Specific interactions of CD47 and its cytoplasmic adapter ubiquilin-1 with components of the exportin-1/Ran nuclear export complex were identified and confirmed by coimmunoprecipitation. Exportin-1 is known to regulate nuclear to cytoplasmic trafficking of 5'-7-methylguanosine (m7G)-modified microRNAs and mRNAs that interact with its cargo protein EIF4E. Interaction with CD47 was inhibited following alkylation of exportin-1 at Cys528 by its covalent inhibitor leptomycin B. Leptomycin B increased levels of m7G-modified RNAs, and their association with exportin-1 in EVs released from wild type but not CD47-deficient cells. In addition to perturbing nuclear to cytoplasmic transport, transcriptomic analyses of EVs released by wild type and CD47-deficient Jurkat T cells revealed a global CD47-dependent enrichment of m7G-modified microRNAs and mRNAs in EVs released by CD47-deficient cells. Correspondingly, decreasing CD47 expression in wild type cells or treatment with thrombospondin-1 enhanced levels of specific m7G-modified RNAs released in EVs, and re-expressing CD47 in CD47-deficient T cells decreased their levels. Therefore, CD47 signaling limits the trafficking of m7G-modified RNAs to EVs through physical interactions with the exportin-1/Ran transport complex.

Identification of Schlafen-11 as a Target of CD47 Signaling That Regulates Sensitivity to Ionizing Radiation and Topoisomerase Inhibitors

Knockdown or gene disruption of the ubiquitously expressed cell surface receptor CD47 protects non-malignant cells from genotoxic stress caused by ionizing radiation or cytotoxic chemotherapy but sensitizes tumors in an immune competent host to genotoxic stress. The selective radioprotection of non-malignant cells is mediated in part by enhanced autophagy and protection of anabolic metabolism pathways, but differential H2AX activation kinetics suggested that the DNA damage response is also CD47-dependent. A high throughput screen of drug sensitivities indicated that CD47 expression selectively sensitizes Jurkat T cells to inhibitors of topoisomerases, which are known targets of Schlafen-11 (SLFN11). CD47 mRNA expression positively correlated with schlafen-11 mRNA expression in a subset of human cancers but not the corresponding non-malignant tissues. CD47 mRNA expression was also negatively correlated with SLFN11 promoter methylation in some cancers. CD47 knockdown, gene disruption, or treatment with a CD47 function-blocking antibody decreased SLFN11 expression in Jurkat cells. The CD47 signaling ligand thrombospondin-1 also suppressed schlafen-11 expression in wild type but not CD47-deficient T cells. Re-expressing SLFN11 restored radiosensitivity to a CD47-deficient Jurkat cells. Disruption of CD47 in PC3 prostate cancer cells similarly decreased schlafen-11 expression and was associated with a CD47-dependent decrease in acetylation and increased methylation of histone H3 in the SLFN11 promoter region. The ability of histone deacetylase or topoisomerase inhibitors to induce SLFN11 expression in PC3 cells was lost when CD47 was targeted in these cells. Disrupting CD47 in PC3 cells increased resistance to etoposide but, in contrast to Jurkat cells, not to ionizing radiation. These data identify CD47 as a context-dependent regulator of SLFN11 expression and suggest an approach to improve radiotherapy and chemotherapy responses by combining with CD47-targeted therapeutics.

Small bowel fed response as measured by wireless motility capsule: Comparative analysis in healthy, gastroparetic, and constipated subjects

BACKGROUND

Small bowel fed response is an increased contractile activity pattern following the ingestion of a meal. Postprandial motility is traditionally evaluated using small bowel manometry. Wireless motility capsule (WMC) is an ingestible wireless capsule that measures pH, temperature, and intraluminal pressure. The primary aim of the study was to assess small bowel fed response captured with the non-invasive WMC. The secondary aim was to compare the fed response patterns between healthy subjects and patients with motility disorders of gastroparesis and constipation.

METHODS

All subjects had 250 cc Ensure^® meal 6 hours after WMC ingestion. Frequency of contractions (Ct), area under the curve (AUC), and motility index (MI) were analyzed during 30 minutes of pre-prandial baseline and 60 minutes postprandially in 20-minute windows.

KEY RESULTS

One hundred and eighty-eight subjects (107 healthy, 23 gastroparetics, 58 constipated) were analyzed. Healthy: Ct, AUC, and MI all increased significantly immediately after meal ingestion (P < .01). Motility parameters peak at 20-40 minutes postmeal. The motor activity decreased at the end of postprandial hour, but was still significantly higher than the fasting baseline (P < .01). Gastroparetics: All motility parameters failed to increase significantly compared to the baseline throughout the entire postprandial hour. Constipated: The fed response was similar to healthy subjects.

CONCLUSIONS AND INFERENCES

The small bowel fed response was readily observed in healthy and chronic constipation subjects with WMC but is blunted in gastroparetics. A blunted small bowel fed response suggests neuropathic changes outside the stomach and may contribute to postprandial symptoms.

Cross cultural comparison of constipation profiles at tertiary care centers between India and USA

BACKGROUND

Despite potential differences in patient perception of chronic constipation (CC) in geographically and culturally distinct regions, head-to-head studies comparing the clinical profile, constipation severity, impact on quality of life (QOL) and economic impact are lacking.

METHODS

We conducted a cross-sectional cohort study of patients presenting with CC to tertiary care centers in the USA and India. Standardized instruments were used to assess constipation subtype, disease severity, disease-specific QOL, somatization, and psychiatric comorbidities. We used multivariable linear regression to determine the predictors of QOL and number of healthcare visits.

KEY RESULTS

Sixty-six and 98 patients with CC were enrolled in the USA and India, respectively. Indian patients with CC had significantly more frequent bowel movements/week compared to their USA counterparts (Median 5 vs 3, P < .0001). The proportion of patients with Bristol stool form scale type 1 and 2 was significantly higher in the USA compared to India (65.5% vs 48%, P = .04). Higher depression score (P = .001), more severe constipation symptoms (P = .001) and site of the study being USA (P = .008) independently predicted worse QOL. Indian patients (P < .001) and worse QOL (P = .02) were independent predictors of number of healthcare visits in the last 12 months.

CONCLUSIONS AND INFERENCES

Indian patients with CC have more frequent and softer bowel movements compared to those in the USA suggesting significant differences in perception of CC in different geographic and cultural settings. QOL and economic impact related to constipation varies with geographic/cultural setting irrespective of other clinical and psychosomatic features.

Gender differences in chronic constipation on anorectal motility

BACKGROUND

The epidemiology of chronic constipation (CC) skews toward female predominance, yet men make up an important component of those suffering from CC. We sought to determine whether there are sex-specific differences in symptoms and physiologic parameters on anorectal manometry (ARM).

METHODS

We performed a case-control analysis of sequential men and age-matched women (2:1 ratio) presenting for ARM as part of the evaluation of CC. We collected physiologic parameters derived from 3D high-resolution ARM in addition to the ROME III constipation module and the Pelvic Floor Distress Inventory 20 (PFDI-20) questionnaires. We analyzed univariate, sex-specific differences in ARM physiologic parameters and PFDI-20 parameters and adjusted for putative confounders using multivariate logistic regression.

KEY RESULTS

Our study enrolled 80 men and 165 age-matched women. Men had a higher median sphincter resting pressure (81.2 vs 75.2 mm Hg, P=.01) and mean squeeze pressure (257.0 vs 170.5 mm Hg, P<.0001) than women. Although men reported significantly less severe straining and incomplete evacuation, they had greater mean rectoanal pressure differential (-106.7 vs -71.1 mm Hg, P<.0001), smaller mean defecation index (0.17 vs 0.27, P=.03) and higher volume threshold for urgency (115.2 v. 103.4 mL, P=.03). However, women were more likely to have abnormal balloon expulsion time (BET) than men (52.7% vs 35.0%, P=.01). After multivariate analysis, male gender was the only independent predictor of a normal BET (OR: 0.48, 95% CI: 0.27-0.86, P=.01).

CONCLUSIONS & INFERENCES

Men and women with CC differ with regard to symptom severity and physiologic parameters derived from ARM suggesting differences in their pathophysiology.

Regional gastrointestinal transit and pH studied in 215 healthy volunteers using the wireless motility capsule: influence of age, gender, study country and testing protocol

BACKGROUND

The wireless motility capsule (WMC) offers the ability to investigate luminal gastrointestinal (GI) physiology in a minimally invasive manner.

AIM

To investigate the effect of testing protocol, gender, age and study country on regional GI transit times and associated pH values using the WMC.

METHODS

Regional GI transit times and pH values were determined in 215 healthy volunteers from USA and Sweden studied using the WMC over a 6.5-year period. The effects of test protocol, gender, age and study country were examined.

RESULTS

For GI transit times, testing protocol was associated with differences in gastric emptying time (GET; shorter with protocol 2 (motility capsule ingested immediately after meal) vs. protocol 1 (motility capsule immediately before): median difference: 52 min, P = 0.0063) and colonic transit time (CTT; longer with protocol 2: median 140 min, P = 0.0189), but had no overall effect on whole gut transit time. Females had longer GET (by median 17 min, P = 0.0307), and also longer CTT by (104 min, P = 0.0285) and whole gut transit time by (263 min, P = 0.0077). Increasing age was associated with shorter small bowel transit time (P = 0.002), and study country also influenced small bowel and CTTs. Whole gut and CTTs showed clustering of data at values separated by 24 h, suggesting that describing these measures as continuous variables is invalid. Testing protocol, gender and study country also significantly influenced pH values.

CONCLUSIONS

Regional GI transit times and pH values, delineated using the wireless motility capsule (WMC), vary based on testing protocol, gender, age and country. Standardisation of testing is crucial for cross-referencing in clinical practice and future research.

A combined HRV-fMRI approach to assess cortical control of cardiovagal modulation by motion sickness

Nausea is a commonly occurring symptom typified by epigastric discomfort with the urge to vomit. To date, the brain circuitry underlying the autonomic nervous system response to nausea has not been fully understood. Functional MRI (fMRI), together with a point process adaptive recursive algorithm for computation of the high-frequency (HF) index of heart rate variability (HRV) was combined to evaluate the brain circuitry underlying autonomic nervous system response to nausea. Alone, the point process analysis revealed increasing sympathetic and decreasing parasympathetic response during nausea with significant increased heart rate (HR) and decreased HF. The combined HRV-fMRI analysis demonstrated that the fMRI signal in the medial prefrontal cortex (MPFC) and pregenual anterior cingulate cortex (pgACC), regions of higher cortical functions and emotion showed a negative correlation at the baseline and a positive correlation during nausea. Overall, our findings confirm a sympathovagal shift (toward sympathetic) during nausea, which was related to brain activity in regions associated with emotion and higher cognitive function.

Evaluating symptom outcomes in gastroparesis clinical trials: validity and responsiveness of the Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD)

BACKGROUND

Patient-reported symptom scales are needed to evaluate treatments for gastroparesis. The Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD) was developed to assess daily symptoms of gastroparesis. This study evaluated the validity and responsiveness of the GCSI-DD in patients with gastroparesis.

METHODS

Symptomatic patients were started with a new treatment for gastroparesis. Patients completed the GCSI-DD each evening during a baseline week and for 8 weeks of treatment. Responders were defined based on patient and clinician global rating of change. Minimal important differences (MID) were estimated based on baseline to 4 week changes in symptoms scores for small improvements.

KEY RESULTS

Of 69 patients participating, 46 had idiopathic, 19 diabetic, and four postfundoplication gastroparesis. Excellent test-retest reliability was seen for GCSI-DD scores, and there were significant correlations between GCSI-DD scores and clinician ratings of symptom severity. Responders to treatment reported improvements in nausea [effect size (ES) = 0.42, P < 0.001], postprandial fullness, ES = 0.83, P < 0.001), bloating (ES = 0.34, P < 0.001), early satiety (ES = 0.53, P < 0.001), but lower responses for upper abdominal pain (ES = 0.29), and vomiting (ES = 0.22; P = 0.119). MIDs were 0.55 for nausea, 0.97 for excessive fullness, 0.63 for bloating, 0.77 for postprandial fullness, and 0.30 for abdominal pain. A composite score of four symptoms (Composite-1; nausea, bloating, excessive fullness, postprandial fullness) had ES of 0.61 and MID of 0.73. Composite-2 score (nausea, early satiety, bloating, abdominal pain) had a lower ES of 0.47.

CONCLUSIONS & INFERENCES

Symptoms of early satiety, nausea, postprandial fullness, and bloating were responsive to treatment for gastroparesis. A composite of these symptoms also demonstrates validity and responsiveness to treatment for gastroparesis, and may represent an acceptable endpoint for evaluating the effectiveness of medical treatments in clinical trials for gastroparesis.

Comparative analysis of phase III migrating motor complexes in stomach and small bowel using wireless motility capsule and antroduodenal manometry

BACKGROUND

  Assessment of phase III MMC is often not performed due to the invasive nature of antroduodenal manometry used to detect it. The aim of the study was to evaluate the ability of wireless motility capsule (WMC) to detect phase III MMC and correlate it with the simultaneous measurements by antroduodenal manometry (ADM).

METHODS

  Eighteen patients underwent simultaneous ADM and WMC. MMCs were identified first on ADM and then correlated with WMC events occurring simultaneously. Frequency of contractions per min, AUC, MI, and criteria for amplitude thresholds of contractions representing MCCs on WMC tracings were defined.

KEY RESULTS

  In 18 patients, a total of 29 MMCs were recorded by ADM. WMC detected 86% of MMC events measured by ADM. Hundred percent (10/10) of MMCs in stomach were detected by WMC, whereas 79% (15/19) of MMCs were detected in SB. The sensitivity and specificity of WMC high amplitude contractions to represent phase III MMC were 90% and 71.8% in the stomach; 73.7% and 84.7% in SB, respectively, and negative predictive value was 99.9% in both regions.

CONCLUSIONS & INFERENCES

  Wireless motility capsule was able to detect the phase III MMCs as the high amplitude contractions with good fidelity. WMC does not detect the propagation of MMC. Using the pressure thresholds, WMC can detect high amplitude contraction representing phase III MMC with favorable sensitivity/specificity profile and 99.9% negative predictive value. This observation may have clinical significance, as the absence of high amplitude contractions recorded by WMC during fasting state suggests absence of MMCs.

Pooled analysis of brain activity in irritable bowel syndrome and controls during rectal balloon distension

BACKGROUND

Brain-imaging literature of irritable bowel syndrome (IBS) suggests an abnormal brain-gut communication. We analyzed the literature to evaluate and compare the aspects of brain activity in individuals with IBS and control subjects experiencing controlled rectal stimulation.

METHODS

PubMed was searched until September 2010. Data from 16 articles reporting brain activity during rectal balloon distensions in IBS compared to control groups was analyzed. Prevalence rates and pairwise activations were assessed using binomial distributions for 11 selected regions of interest. The data were aggregated to adjust for center effect.

KEY RESULTS

There was considerable variability in the literature regarding regions and their activity patterns in controls and individuals with IBS. There was no significant difference found in the thalamus, anterior cingulate cortex, posterior cingulate cortex, and prefrontal cortex, however, results show limited evidence of consensus for the anterior insula (AI) (P = 0.22). Pairwise activity results suggest that pairs involving the AI tend to have more consistent activity together than pairs which do not involve the AI (posterior insula and AI, P = 0.08; posterior cingulate cortex and AI, P = 0.16), however, no pairwise evaluation reached significance.

CONCLUSIONS & INFERENCES

Our pooled analysis demonstrates that the literature reports are quite heterogeneous but there is some evidence that there may be patterns of higher activity more common in individuals with IBS than in controls. A consensus, though, regarding study designs, analysis approach and reporting could create a clearer understanding of brain involvement in IBS pathophysiology.

Motility of the antroduodenum in healthy and gastroparetics characterized by wireless motility capsule

BACKGROUND

The wireless motility capsule (WMC) measures intraluminal pH and pressure, and records transit time and contractile activity throughout the gastrointestinal tract. Our hypothesis is that WMC can differentiate antroduodenal pressure profiles between healthy people and patients with upper gut motility dysfunctions. This study aims to analyze differences in the phasic pressure profiles of the stomach and small intestine in healthy and gastroparetic subjects.

METHODS

Data from 71 healthy and 42 gastroparetic subjects were analyzed. The number of contractions (Ct), area under the pressure curve and motility index (MI = Ln (Ct *sum amplitudes +1)) were analyzed for 60 min before gastric emptying of the capsule (GET), (gastric window) and after GET (small bowel window) and results between groups were compared with the Wilcoxon rank sum test.

KEY RESULTS

Significant differences were observed between healthy and gastroparetic subjects for Ct and MI (P < 0.05). Median values of the motility parameters in gastric window were Ct = 72, MI = 11.83 for healthy and Ct = 47, MI = 11.12 for gastroparetics. In the small bowel, median values were Ct = 144.5, MI = 12.78 for healthy and Ct = 93, MI = 12.12 for gastroparetics. Diabetic subjects with gastroparesis showed significantly lower Ct and MI compared with healthy subjects in both gastric and small bowel windows while idiopathic gastroparetic subjects did not show significant differences.

CONCLUSIONS & INFERENCES

The WMC is able to differentiate between healthy and gastroparetic subjects based on gastric and small bowel motility profiles.

Gastroparesis and functional dyspepsia: excerpts from the AGA/ANMS meeting

BACKGROUND

Despite the relatively high prevalence of gastroparesis and functional dyspepsia, the aetiology and pathophysiology of these disorders remain incompletely understood. Similarly, the diagnostic and treatment options for these two disorders are relatively limited despite recent advances in our understanding of both disorders.

PURPOSE

This manuscript reviews the advances in the understanding of the epidemiology, pathophysiology, diagnosis, and treatment of gastroparesis and functional dyspepsia as discussed at a recent conference sponsored by the American Gastroenterological Association (AGA) and the American Neurogastroenterology and Motility Society (ANMS). Particular focus is placed on discussing unmet needs and areas for future research.

The assessment of regional gut transit times in healthy controls and patients with gastroparesis using wireless motility technology

BACKGROUND

Wireless pH and pressure motility capsule (wireless motility capsule) technology provides a method to assess regional gastrointestinal transit times.

AIMS

To analyse data from a multi-centre study of gastroparetic patients and healthy controls and to compare regional transit times measured by wireless motility capsule in healthy controls and gastroparetics (GP).

METHODS

A total of 66 healthy controls and 34 patients with GP (15 diabetic and 19 idiopathic) swallowed wireless motility capsule together with standardized meal (255 kcal). Gastric emptying time (GET), small bowel transit time (SBTT), colon transit time (CTT) and whole gut transit time (WGTT) were calculated using the wireless motility capsule.

RESULTS

Gastric emptying time, CTT and WGTT but not SBTT were significantly longer in GP than in controls. Eighteen percent of gastroparetic patients had delayed WGTT. Both diabetic and idiopathic aetiologies of gastroparetics had significantly slower WGTT (P < 0.0001) in addition to significantly slower GET than healthy controls. Diabetic gastroparetics additionally had significantly slower CTT than healthy controls (P = 0.0054).

CONCLUSIONS

In addition to assessing gastric emptying, regional transit times can be measured using wireless motility capsule. The prolongation of CTT in gastroparetic patients indicates that dysmotility beyond the stomach in GP is present, and it could be contributing to symptom presentation.

Development and content validity of a gastroparesis cardinal symptom index daily diary

BACKGROUND

The Gastroparesis Cardinal Symptom Index (GCSI) is a patient-reported outcome for gastroparesis using a two-week recall period. To minimize potential patient recall effects, a daily diary version of the GCSI (GCSI-DD) was developed.

AIMS

To evaluate the content validity of GCSI-DD for the symptoms in patients with documented gastroparesis, to capture symptom variability over time and to compare responses of this GCSI-DD to the original GCSI.

METHODS

In gastroparesis adults with delayed gastric emptying, cognitive debriefing interviews were conducted to elicit their perspective on relevant symptoms of gastroparesis and relevant recall periods and to evaluate patient understanding of GCSI-DD. Patients completed the GCSI-DD daily over a 2-week period and completed the GCSI at baseline and the 2-week follow-up visit.

RESULTS

Twelve gastroparesis patients, of whom five were diabetic and nine women, reported nausea (100%), vomiting (100%), stomach fullness (75%), bloating (58%) and loss of appetite (50%) were important symptoms. All patients understood diary instructions and item content and reported that the diary captured their gastroparesis symptom experience; 83% considered response scales adequate. There was significant daily variability in GCSI-DD scores. Mean GCSI-DD subscale and total scores over 2 weeks correlated strongly (all r > 0.90) with GCSI scores at 2-week follow-up.

CONCLUSIONS

The GCSI-DD includes symptoms relevant to patients with gastroparesis, captures daily variability of those symptoms and has psychometric properties consistent with a good patient-reported outcome endpoint for gastroparesis clinical trials.

Effect of AbGn-7, a glycotope-specific monoclonal antibody, on apoptosis in colon cancer cells and tumor growth in xenograft models

e15118

Background: While clinical benefit against colorectal cancer has been observed with therapeutic monoclonal antibodies such as bevacizumab, cetuximab and panituzumab, the death rate of advanced colorectal cancer remains high that warrants further development of more potent therapeutics. Methods: A cell-based immunization approach was used to generate monoclonal antibodies against targets expressed on human colorectal cancer cells. A chimeric monoclonal antibody, AbGn-7, was selected and evaluated for the potential clinical use to treat colorectal cancer. Results: Expression of AbGn-7 antigen: Carbohydrate competition assay demonstrated that AbGn-7 recognizes a Lewis-A-like carbohydrate antigen (AbGn-7 antigen). Immunohistochemical studies showed that AbGn-7 antigen is expressed in colorectal cancer tissue. No significant binding could be detected in non-tumor tissues except in the epithelia of GI track. Effector function of AbGn-7: AbGn-7 triggered dose-dependent apoptosis in COLO 205 colon cancer cell. In addition, AbGn-7 elicited potent complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC) in a dose-dependent manner. Molecular mechanism of apoptosis induced by AbGn-7: Tunel assay, PARP cleavage assay as well as caspase inhibitor studies demonstrated that AbGn-7 induced apoptosis in COLO 205 colon cancer cells via a caspase-independent pathway. Xenograft study: AbGn-7 alone, or in combination with 5FU-Leucovorin, effectively inhibited the growth of COLO 205 xenograft in SCID mice and prolonged their survival. Conclusions: The results of the present study suggest that AbGn-7 is a potential candidate for effective treatment of colorectal cancer.

[Table: see text]

Dynamic Cardiovagal Response to Motion Sickness: A Point-Process Heart Rate Variability Study

A visual display of stripes was used to examine cardio-vagal response to motion sickness. Heart rate variability (HRV) was investigated using dynamic methods to discern instantaneous fluctuations in reaction to stimulus and perception-based events. A novel point process adaptive recursive algorithm was applied to the R-R series to compute instantaneous heart rate, HRV, and high frequency (HF) power as a marker of vagal activity. Results show interesting dynamic trends in each of the considered subjects. HF power averaged across ten subjects indicates a significant decrease 20s to 60s following the transition from "no nausea" to "mild." Conversely, right before "strong" nausea, the group average shows a transient trending increase in HF power. Findings confirm gradual sympathetic activation with increasing nausea, and further evidence transitory increases in vagal tone before flushes of strong nausea.

Comparison of gastric emptying of a nondigestible capsule to a radio-labelled meal in healthy and gastroparetic subjects

BACKGROUND

Gastric emptying scintigraphy (GES) using a radio-labelled meal is used to measure gastric emptying. A nondigestible capsule, SmartPill, records luminal pH, temperature, and pressure during gastrointestinal transit providing a measure of gastric emptying time (GET).

AIMS

To compare gastric emptying time and GES by assessing their correlation, and to compare GET and GES for discriminating healthy subjects from gastroparetics.

METHODS

Eighty-seven healthy subjects and 61 gastroparetics enrolled with simultaneous SmartPill and GES. Fasted subjects were ingested capsule and [(99m)Tc]-SC radio-labelled meal. Images were obtained every 30 min for 6 h. Gastric emptying time and percentage of meal remaining at 2/4 h were determined for each subject. The sensitivity/specificity and receiver operating characteristic analysis of each measure were determined for each subject.

RESULTS

Correlation between GET and GES-4 h was 0.73 and GES-2 h was 0.63. The diagnostic accuracy from the receiver operating characteristic curve between gastroparetics and healthy subjects was GET = 0.83, GES-4 h = 0.82 and GES-2 h = 0.79. The 300-min cut-off time for GET gives sensitivity of 0.65 and specificity of 0.87 for diagnosis of gastroparesis. The corresponding sensitivity/specificity for 2 and 4 h standard GES measures were 0.34/0.93 and 0.44/0.93, respectively.

CONCLUSION

SmartPill GET correlates with GES and discriminates between healthy and gastroparetic subjects offering a nonradioactive, standardized, ambulatory alternative to scintigraphy.

Effects of 5-HT(3) antagonism on postprandial gastric volume and symptoms in humans

BACKGROUND

Alosetron reduces symptoms of dyspepsia, but the physiological basis for the symptomatic benefit is unclear.

AIM

To assess 5-HT3 antagonism on postprandial gastric volume and symptoms after ingestion of maximum tolerable volume of a liquid meal.

METHODS

In 36 healthy volunteers, we assessed effects of placebo, 0.5 and 1 mg b.d. alosetron on fasting and postprandial gastric volumes (using single photon emission computed tomography) and symptoms based on 100 mm VAS, 30 min after maximum volume ingested.

RESULTS

The 5-HT3 antagonist reduced postprandial symptoms (aggregate score: P < 0.05), nausea (P < 0.001), and tended to reduce bloating (P=0.08). Both 0.5 and 1 mg alosetron reduced nausea (P < 0.025); 1 mg alosetron reduced aggregate symptoms (P < 0.05) and bloating (P < 0.05). Effects on pain (P=0.19) and fullness (P=0.14) were not statistically significant. There were no significant effects of the 5-HT3 antagonist on volume of meal tolerated or on SPECT-measured fasting or postprandial gastric volumes.

CONCLUSION

5-HT3 antagonism reduces aggregate symptoms, nausea and bloating after a liquid meal without increase in gastric volumes, suggesting a role for 5-HT3 in afferent functions in healthy humans during the postprandial period.

Development of an orthodontic simulator for measurement of orthodontic forces

In this research we developed an orthodontic simulator for analysis of orthodontic forces distribution in the case of the continuous arch technique. In order to take into account vertical force, besides horizontal force and occlusogingival moment on instrumented artificial tooth, tooth root was designed as a ring load cell. Fixing each artificial tooth onto combined mechanical stages enabled variation of tooth anteroposterior position and inclination related to occlusal plane. Calibration of forces and moment of each instrumented artificial tooth showed linearity of outputs and provided the generalized inverse matrix for evaluation of forces and moments from measured strain data. A simulation to retract the anterior teeth was accomplished, and distribution of forces and moment acting at the bracket of each tooth were determined. The average accuracy was 82% and 97% in the horizontal and vertical direction, respectively, by comparing the applied forces and the evaluated ones.

Genetic strategies to enhance penicillin acylase production in Escherichia coli

We demonstrated the improvement of penicillin acylase (PAC) production by optimization of the host/vector system using genetic engineering strategies. Several expression plasmids with improved efficiency for the transcription of the pac gene and/or translation of the pac mRNA were constructed. Mutant strains, isolated by a novel screening method, were effective for use as the expression host to produce PAC. The feasibility of using the mutant strains harboring a selection of expression plasmids for the production of PAC was evaluated. The effect of the mutation(s) resulting in the improved PAC producing ability was characterized. While the production of PAC was significantly enhanced using the optimized host/vector system, the formation of PAC inclusion bodies was shown to be another step limiting the production of recombinant PAC.

Clinical analysis of Mycobacterium tuberculosis infection in patients with acquired immunodeficiency syndrome

From January 1990 to July 1998, twelve patients (10%) among 120 patients with human immunodeficiency virus infection who were hospitalized in the Veterans General Hospital-Taipei, were proved to have Mycobacterium tuberculosis infection. The mean age of these patients was 38 years, range: 25-62 years. All patients studied were in the advanced stage of acquired immunodeficiency syndrome (AIDS) with a mean circulatory CD4 lymphocyte count of 21/microL (range: 0-64/microL) and a much higher HIV viral load at initial diagnosis of M. tuberculosis infection. Because of no significant difference in the HIV viral load between patients with active pulmonary tuberculosis and those with extrapulmonary tuberculosis in this study, dissemination of M. tuberculosis did not correlate directly with a high HIV viral load, but was possibly related to the virulence of the organism itself. Chest radiographic findings at initial diagnosis of pulmonary tuberculosis were variable and atypical. Most patients (62.5%) presented with a primary pattern (lower lobe or diffuse infiltrates), while hilar lymphadenopathy was noted in more than half of the patients and cavitation was less common (only one patient). Ten patients (83.3%) had extrapulmonary involvement; the most common site being the lymph nodes. Most patients with classic drug-sensitive tuberculosis responded well to conventional standard regimens of anti-tuberculosis therapy. Since tuberculosis is transmittable, treatable, and possibly preventable, moreover the clinical presentation of tuberculosis in the patients with AIDS may be atypical and unusual, clinical physicians must keep an alert dealing with these patients for early identification and early treatment.

Nocturnal gastric acidity and acid breakthrough on different regimens of omeprazole 40 mg daily

BACKGROUND

On chronic intake of omeprazole, most healthy volunteers and patients still have nocturnal acid breakthrough (NAB), defined as night-time periods with gastric pH < 4.0 lasting for longer than 1 h. Gastro-oesophageal reflux during NAB may be particularly injurious to the oesophageal mucosa, contributing to the chronic lesions complicating the condition.

AIM

To compare the effect of three different dosing regimens of omeprazole 40 mg daily with regard to suppressing nocturnal gastric acidity and avoiding NAB.

METHODS

Eighteen healthy volunteers were given three different regimens of omeprazole for 7 days each in randomized order: 40 mg before breakfast (qAM), 40 mg before dinner (qPM) and 20 mg before breakfast and dinner (b.d.). On day 7, 24-h intragastric and intraoesophageal pH-metry was performed. Tracings were analysed for the period from 22.00 h until 06.00 h with regard to the percentage of time at which gastric pH was below 4.0, 3.0 and 2.0, and also the occurrence and duration of NAB.

RESULTS

Nocturnal acid breakthrough was significantly more common on qAM than on qPM and b.d. (P < 0.05) dosing. The percentage of time gastric pH was less than 4.0 overnight was significantly lower on qPM (median 31.3) and b.d. (median 20.5) than on qAM (median 66.3) dosing (P=0.01 and P < 0.02, respectively). A pH threshold of 3 and 4 showed the same differences, as did median 24-h gastric pH. Daytime acidity was not significantly different.

CONCLUSIONS

In healthy volunteers, dinner time or split dosing of omeprazole 40 mg daily is significantly more effective than dosing before breakfast in preventing NAB and controlling gastric acidity. These regimens should be preferred in patients in whom suppression of nocturnal gastric acidity is desirable.

Optimal dosing of omeprazole 40 mg daily: effects on gastric and esophageal pH and serum gastrin in healthy controls

BACKGROUND

Little is known about the best regimen of omeprazole 40 mg/day for suppressing gastric acid and distal esophageal acid exposure. In addition, the relationship between the level of serum gastrin and gastric pH and this therapy is still uncertain.

METHODS

Nineteen healthy male volunteers (mean age 25 yr) had a baseline fasting serum gastrin and 24-h ambulatory combined distal esophageal and gastric pH monitoring. Subjects underwent a 7-day course of each of three specific regimens of omeprazole 40 mg (20 mg b.i.d., 40 mg qAM, 40 mg qPM) with repeat pH and gastrin on day 6. Meals and activity patterns were constant for each subject during the test series. Medications were taken before meals.

RESULTS

All dosing regimens caused significant (p < 0.01) acid reduction compared with baseline in both the stomach and the distal esophagus. There was no significant difference in the amount of acid exposure (time pH < 4) among the three dosing regimens in the esophagus and between qAM and qAM dosing in the stomach. However, b.i.d. dosing gave better (p < 0.05) gastric acid suppression compared with single daily dosing in 15 of 19 subjects. When the baseline was compared with all regimens of omeprazole 40 mg, there was a significant difference with both the serum gastrin (p < 0.01) and the percentage time gastric pH was < 4 (p < 0.01). The correlation between change in serum gastrin and change in percentage time gastric pH was < 4 was poor (r = 0.26).

CONCLUSIONS

Divided dosing of omeprazole 20 mg b.i.d. provides superior gastric acid suppression to either once a day regimen of omeprazole 40 mg in most individuals. Serum gastrin levels do not correspond well to gastric pH, necessitating the use of gastric pH monitoring to accurately determine the response to gastric acid suppression.

The effect of nasogastric intubation on gastroesophageal reflux: a comparison of different tube sizes

OBJECTIVE

Previous reports have revealed conflicting conclusions about whether tubes placed across the esophagogastric junction (EGJ) have promoted reflux and whether there is potential for subsequent esophageal mucosal damage. The purpose of this study was to examine whether commonly used tubes (diameters: 2.1 mm, antimony pH probe and 3.8 mm, nasogastric tube) promote reflux under typical inpatient conditions.

METHODS

Eight asymptomatic volunteers (five male, mean age 27.6 yr) underwent three sessions, each lasting 6 hours postprandially, while supine with the head elevated 20 degrees. In randomized order, the subjects had either a 2.1-mm tube, 3.8-mm tube, and 2.1-mm tube together or no tube across the EGJ. The subjects were fed 500 ml of Ensure Plus at the beginning of the study. Reflux was measured by a pH probe placed 5 cm above the lower esophageal sphincter. The number of reflux episodes, number of reflux episodes more than 5 minutes, longest reflux episode, time esophageal pH was less than 4, and percentage total time pH was less than 4 were evaluated.

RESULTS

Over the 6 hours, no abnormal reflux was shown with either tube size across the EGJ.

CONCLUSIONS

Over a 6-h period, a tube (pH probe alone or combined with nasogastric tube) across the EGJ does not promote an increase in the amount of postprandial supine gastroesophageal reflux in normal volunteers.

Hair zinc, scalp hair quantity, and diaper rash in normal infants

Hair zinc concentration was determined by atomic absorption spectrophotometry in 308 normal newborn infants and 199 normal infants aged one to twelve months. Hair zinc concentration declined from 204 micrograms/gm at birth to 112 micrograms/gm at age eight months, and then rose to 144 micrograms/gm at age twelve months. Diaper rash was significantly associated with reduced hair zinc, and infants with the least hair had lower zinc levels than infants with the most hair. The data indicate that hair loss and diaper rash found in normal infants is significantly associated with a reduction in hair zinc concentration.

Hair zinc levels in infants

Hair zinc concentration was determined by atomic absorption spectrophotometry in 308 normal neonates and in 119 normal infants aged 1 to 12 months. Hair zinc concentration declined from 204 μg/g at birth to 112 μg/g at age 8 months, and then rose to 144 μg/g at age 12 months. Breast-fed infants had higher hair zinc than formula-fed infants.