Clarifying the longitudinal factor structure, temporal stability, and construct validity of Go/No-Go task-related neural activation across adolescence and young adulthood

This study aimed to clarify the psychometric properties and development of Go/No-Go (GNG) task-related neural activation across critical periods of neurobiological maturation by examining its longitudinal stability, factor structure, developmental change, and associations with a computational index of task-general cognitive control. A longitudinal sample (N=289) of adolescents from the Michigan Longitudinal Study was assessed at four time-points (mean number of timepoints per participant=2.05; standard deviation=0.89) spanning early adolescence (ages 10-13) to young adulthood (22-25). Results suggested that regional neural activations from the "successful inhibition" (SI>GO) and "failed inhibition" (FI>GO; error-monitoring) contrasts are each described well by a single general factor. Neural activity across both contrasts showed developmental increases throughout adolescence that plateau in young adulthood. Neural activity metrics evidenced low temporal stability across this period of marked developmental change, and the SI>GO factor showed no relations with a behavioral index of cognitive control. The FI>GO factor displayed stronger criterion validity in the form of significant, positive associations with behaviorally measured cognitive control. Findings emphasize the utility of well-validated psychometric methods and longitudinal data for clarifying the measurement properties of functional neuroimaging metrics and improving measurement practices in developmental cognitive neuroscience.

A mechanical task for measuring sign- and goal-tracking in humans: A proof-of-concept study

Cue-based associative learning (i.e., Pavlovian conditioning) is a foundational component of behavior in almost all forms of animal life and may provide insight into individual differences in addiction liability. Cues can take on incentive-motivational properties (i.e., incentive salience) through Pavlovian learning. Extensive testing with non-human animals (primarily rats) has demonstrated significant variation among individuals in the behaviors this type of learning evokes. So-named "sign-trackers" and "goal-trackers" have been examined in many studies of non-human animals, but this work in humans is still a nascent area of research. In the present proof-of-concept study, we used a Pavlovian conditioned approach task to investigate human sign- and goal-tracking in emerging adults. Conditioned behaviors that developed over the course of the task were directed toward the reward-cue and toward the reward location. Participants' eye-gaze and behavior during the task were submitted to a latent profile analysis, which revealed three groups defined as sign-trackers (n = 10), goal-trackers (n = 4), and intermediate responders (n = 36). Impulsivity was a significant predictor of the sign-tracking group relative to the goal-tracking group. The present study provides preliminary evidence that a simple procedure can produce learned Pavlovian conditioned approach behavior in humans. Though further investigation is required, findings provide a promising step toward the long-term goal of translating important insights gleaned from basic research into treatment strategies that can be applied to clinical populations.

Abstract P4-08-35: Young age at diagnosis is associated with worse prognosis in the luminal A breast cancer subtype. A retrospective institutional cohort study

Background: Breast cancer (BCA) presents with distinct molecular subtypes, each associated with different patterns of relapse, drug sensitivity, and prognosis. Although age at diagnosis is a recognized independent prognostic risk factor, its relative importance among molecular subtypes is not well documented. The aim of this study was to evaluate the prognostic role of age at diagnosis among BCA patients of different immunohistochemical subtypes (LuminalA, LuminalB, Her2, Triple-negative).

Methods: We conducted a retrospective study of women with invasive BCA undergoing surgery at the Johns Hopkins Hospital from January 2000 - December 2016, excluding patients presenting with stage IV breast cancer. Patients were stratified into three age groups: ≤ 40, 41-60, and > 60 years, and multivariable analysis was performed using Cox regression. To explore age-related differences in gene expression, we identified differentially expressed genes (DEG) between age groups among BCA subtypes in the TCGA dataset. Finally, we identified key driver genes within DEG using a weighted gene co-expression network analysis.

Results: Our cohort included 3,524 patients with a median follow-up of 85.1 months. LuminalA breast cancer patients had significantly lower 5-year Disease Free Survival (DFS) and Distant Metastasis-Free Survival (DMFS) in the ≤ 40 year age group compared to the 40-60 year age group (HR=2.69, 95%CI: 1.72 - 4.23 and HR=2.95, 95%CI: 1.78 - 4.90, respectively), while the other molecular subtypes showed no significant association of DFS or DMFS with age. Age was a stronger predictor of 5- year DFS and 5-year DMFS than tumor grade or proliferative index (Ki67) in LuminalA BCA patients, but not other subtypes.

Gene expression data were obtained from 1097 BCA TCGA patients, divided into two groups (≤40y, n=36; >40y, n=455). We identified 374 DEG between ≤40y and >40y LuminalA BCA subsets. The DEG were enriched in 7 pathways, and the WGCNA analysis identified two modules of co-expressed genes. No age group-specific DEG were identified in non-LuminalA subtypes.

Conclusion: Age at diagnosis may be an important prognostic factor in LuminalA BCA and may improve risk stratification and personalized therapy. Prospective studies are needed to further evaluate the prognostic value of age in this subset of BCA patients.

Citation Format: Liu Z, Sahli Z, Wang Y, Wolff AC, Cope L, Umbricht CB. Young age at diagnosis is associated with worse prognosis in the luminal A breast cancer subtype. A retrospective institutional cohort study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-35.

Abstract P5-12-04: A new method of data analysis to derive DNA methylation signatures that stratify risk of recurrence in triple negative breast cancer

Background: Triple negative breast cancer (TNBC) accounts for 10-17% of all breast cancer and is more likely to be of higher histological grade, poorly differentiated, associated with a higher recurrence rate and with decreased overall survival. The clinical course of a TNBC patient remains difficult to predict, as tumors with homogenous morphological characteristics may vary in response to therapy and have divergent outcomes. Therefore, additional analytical methods are needed to better classify TNBC. Our goal is to refine the analysis of methylome datasets to derive reliable molecular signatures that can distinguish TNBC patients with good outcomes who may benefit from less aggressive treatment, from those with poor outcomes who would be candidates for more aggressive treatments.

Methods: Our laboratory has conducted and reported, in this meeting, results from analysis of 450k methylation array data on a discovery set of 53 high-risk TNBC cases and 62 low-risk controls treated by locoregional therapy alone, as well as 5 normal breast tissue samples. High-risk cases were defined as patients that relapsed within 0.5 to 6.5 years from the time of diagnosis, while low-risk controls had no relapse and >4 year recurrence-free intervals (RFI). In this work, we devised and applied a novel methylation biomarker discovery program named Hypermethylated Outlier Detector (HOD) that emphasizes the selection of highly methylated markers in cases compared to controls, to find a high-risk signature in the TNBC discovery set. The methylation signature identified by HOD was interrogated in a test set of 50 TNBCs (with 16 recurrences) that did not receive chemotherapy, and in a second test set of 131 TNBCs (with 33 recurrences) that did receive chemotherapy.

Results: HOD identified 39 hypermethylated markers (beta >0.20) that could accurately distinguish between the high-risk cases and the low-risk controls in the discovery set of TNBCs (n=115) treated with locoregional therapy alone. In the test set of TNBC (n=50) with no chemotherapy the 39 markers distinguished high from low risk individuals (likelihood ratio test P=0.049). In a second test set of TNBC (n=131) that received chemotherapy the 39 hypermethylated markers again distinguished high from low risk individuals (likelihood ratio test P=0.0043).

Conclusions: We have presented evidence that a methylation signature identified by HOD can be used to identify TNBC patients that have a high-risk of relapse regardless of receiving chemotherapy. This methylation signature could potentially be used to inform physician decisions on therapeutic strategies for TNBC patients. This could ultimately lead to less aggressive treatment given to patients possessing a methylation profile consistent with a better prognosis. Conversely, patients with hypermethylation in the 39 markers will likely benefit from a more aggressive course of treatment.

Citation Format: Downs BM, Cope LM, Fackler MJ, Cho S, Wolff AC, Regan MM, Sukumar S, Umbricht CB. A new method of data analysis to derive DNA methylation signatures that stratify risk of recurrence in triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-12-04.

Abstract P4-08-09: DNA methylation markers predict recurrence-free interval in triple-negative breast cancer

BACKGROUND. Chemotherapy remains the treatment mainstay for triple-negative breast cancer (TNBC). Nevertheless, randomized trials have shown that not all TNBC require it, nor does it benefit all patients that receive it. Molecular tools to risk-stratify TNBC are currently lacking. In light of the importance of epigenetic processes modulating gene expression, we performed an array-based genome-wide DNA methylation search in well-documented institutional and clinical trial cohorts of TNBC for markers that can distinguish breast cancers with a favorable natural history from those with a high risk of recurrence.

METHODS. We performed an array-based genome-wide DNA methylation survey of well-documented institutional and clinical trial cohorts of TNBC and conducted molecular marker discovery on institutional TNBCs (115 patient samples; 53 recurrences) treated by locoregional therapy (LRT) alone. The identified hypermethylated gene signatures were then tested in a TNBC cohort (50 patient samples; 16 recurrences) from the no chemotherapy arms of IBCSG trials VIII and IX, and in a separate combined cohort of TNBCs (131 patient samples; 33 recurrences) treated with chemotherapy from an institutional repository and from IBCSG trials VIII and IX. Cross platform validation was conducted using quantitative multiplexed methylation specific PCR (QM-MSP) on hypermethylated markers in samples from both the Discovery Set and IBCSG LRT Test Set.

RESULTS. We identified methylation signatures in the discovery cohort consisting of 100 or 30 CpG probes that discriminated patients who remained recurrence-free from those with recurrent disease. These signatures were then tested in the IBCSG no chemotherapy cohort, and we found that hypermethylation was associated with shorter recurrence-free interval (RFI). A significant association of both 100 CpG (P<0.0001) and 30 CpG (P=0.0021) signatures with shorter RFI was found in the combined institutional and IBCSG chemotherapy cohort. We observed an enrichment of methylation probes residing on chromosome 19, particularly within 19q13.41-43, that significantly correlated with RFI following chemotherapy. QM-MSP results reflected that of the methylation array [Spearman correlation coefficient of r = 0.495 (P = 0.0009)] indicating that the relationship between high methylation and short RFI is detectable independent of analytical platform. We also observed enrichment for Chromosome 19-specific probes within the 100 and 30 probe sets. While only 5% of all CpG markers are located within Chr19, 15% of the 100 CpG set, 37% of the 30 CpG set, and 47% of the 17 CpGs that are statistically significantly correlated with RFI in the chemotherapy group reside on the Chr19, mostly within 19q13.41-43.

CONCLUSIONS. Methylation markers may be of prognostic importance in TNBC and our findings should be validated in additional clinical trial cohorts.

Citation Format: Fackler MJ, Cho SS, Cope LM, Gabrielson E, Wilsbach K, Lynch C, Marks JR, Geradts J, Regan MM, Viale G, Wolff AC, Umbricht CB, Sukumar S. DNA methylation markers predict recurrence-free interval in triple-negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-09.

Abstract P6-03-07: An automated DNA methylation assay (QM-MSP) for rapid breast cancer diagnosis in underdeveloped countries

BACKGROUND: Underdeveloped countries reported 882,900 new cases of breast cancer and 324,000 deaths in 2012, likely to be a gross underestimation according to recent reports. Often, mammography screening is not available, primary care services are limited, and pathology and treatment services are available only in the regional hospitals. Because of the lack of access to diagnostic and treatment services, it is estimated that more than 90% of patients with breast cancer never present for medical treatment. To address this situation, an accurate, easy-to-perform diagnostic test appropriate for use in remote clinics is desperately needed. Johns Hopkins (JH) and Cepheid partnered to translate a robust Quantitative Multiplex Methylation-Specific PCR (QM-MSP) assay to an automated, cartridge-based system that provides quantitative measures of DNA methylation within hours of fine needle aspiration or core biopsy of image-detected suspicious lesions.

METHODS: With a goal of discriminating malignant from benign breast disease with high sensitivity and specificity, we evaluated 24 breast cancer-specific DNA methylation markers (selected through comprehensive methylome analysis) in 119 invasive ductal carcinomas and 186 benign breast tissues. QM-MSP was performed on sections of formalin-fixed paraffin-embedded (FFPE) tissues to quantify DNA methylation. The dynamic range and performance of quantitative methylation detection was tested using a subset of 9 genes in the cartridge-based system.

RESULTS: QM-MSP was performed in a Training set consisting of 93 tissues [n=43 IDC, n=50 benign lesions (25 usual ductal hyperplasia, UDH, and 25 papilloma)] from the US. We selected 9 DNA markers significantly (p<0.05) more methylated in malignant compared to benign lesions, which had low or no methylation. An independent Test set consisted of benign (n=26) and malignant (n=10) tissues (mostly Caucasian; JH Test Set). As a panel, the 9 markers were significantly more methylated in malignant than benign tissue (p<0.001), revealing a sensitivity of 90% and specificity of 92%, using a laboratory cutoff of 9.5 CMI units (900 unit scale) based on receiver operator characteristic statistics (ROC; p<0.0001, AUC=0.977). To determine if the markers characterized in the JH Test Set could perform as well in samples from a different geography, the panel was tested on 176 tissues from Wuhan, China (China Test Set). In this cohort (66 IDC and 110 benign tissues - 49 fibroadenoma, 19 benign cyst, 12 UDH, 30 papilloma), sensitivity was 89% and specificity was 89% for detection of breast cancer with ROC AUC=0.945. An advanced version of the cartridge with up to 12 methylated DNA markers is under development, thus far showing robust signals in cancer and low background in benign tissues. Current work at JH is focused on optimizing the technical performance of the cartridge.

CONCLUSIONS: We identified a panel of methylated DNA markers that discriminate malignant from benign breast lesions and built a prototype automated cartridge-based assay with promising sensitivity and specificity for breast cancer. Such an assay has the potential to aid in specimen triage in the pathology lab and provide fast, low cost and accurate diagnosis of breast cancer in LMIC settings.

Citation Format: Fackler MJ, Downs BM, Mercado-Rodriguez C, Cimino-Mathews A, Chen C, Yuan J, Cope LM, Kohlway A, Kocmond K, Lai E, Weidler J, Visvanathan K, Umbricht CB, Harvey S, Wolff AC, Bates M, Sukumar S. An automated DNA methylation assay (QM-MSP) for rapid breast cancer diagnosis in underdeveloped countries [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-03-07.

Transfemoral Digital Subtraction Aortography

The ionic monomer, sodium diatrizoate at 150 mg I/ml (726 mosmol/kg) and the non-ionic monomer, iopamidol, diluted to the same iodine concentration but at 324.3 mosmol/kg, were randomly allocated to patients undergoing transfemoral intra-arterial digital subtraction angiography for lower limb peripheral vascular disease. The agents produced images of comparable quality and diagnostic efficacy. There were no significant differences between the media regarding sensations of pain and warmth. Minor neurological symptoms (headache and dizziness) occurred 7 times more frequently with the ionic monomer. There was a slight but temporary rise in plasma potassium one hour after injection of the ionic monomer but no evidence of appreciable intravascular haemolysis. The non-ionic monomer caused a slight fall in haemoglobin and haematocrit one hour after injection which is attributed to osmotic haemodilution. It is concluded that a diluted high osmolar contrast agent is an acceptable alternative to a low osmolar agent in transfemoral digital subtraction lower limb aortography.

Abnormal brain structure in youth who commit homicide

BACKGROUND

Violence that leads to homicide results in an extreme financial and emotional burden on society. Juveniles who commit homicide are often tried in adult court and typically spend the majority of their lives in prison. Despite the enormous costs associated with homicidal behavior, there have been no serious neuroscientific studies examining youth who commit homicide.

METHODS

Here we use neuroimaging and voxel-based morphometry to examine brain gray matter in incarcerated male adolescents who committed homicide (n = 20) compared with incarcerated offenders who did not commit homicide (n = 135). Two additional control groups were used to understand further the nature of gray matter differences: incarcerated offenders who did not commit homicide matched on important demographic and psychometric variables (n = 20) and healthy participants from the community (n = 21).

RESULTS

Compared with incarcerated adolescents who did not commit homicide (n = 135), incarcerated homicide offenders had reduced gray matter volumes in the medial and lateral temporal lobes, including the hippocampus and posterior insula. Feature selection and support vector machine learning classified offenders into the homicide and non-homicide groups with 81% overall accuracy.

CONCLUSIONS

Our results indicate that brain structural differences may help identify those at the highest risk for committing serious violent offenses.

How can the interprofessional relationship between community pharmacists and GPs in Sefton Health Authority be improved for the benefit of patients?

Focal points

Transcriptional regulation of Wnt inhibitory factor-1 by Miz-1/c-Myc

The Wnt signaling pathway is capable of self-regulation through positive and negative feedback mechanisms. For example, the oncoprotein c-Myc, which is upregulated by Wnt signaling activity, participates in a positive feedback loop of canonical Wnt signaling through repression of Wnt antagonists DKK1 and SFRP1. In this study, we investigated the mechanism of Wnt inhibitory factor-1 (WIF-1) silencing. Mapping of CpG island methylation of the WIF-1 promoter reveals regional methylation (-295 to -95 bp from the transcription start site) that correlates with transcriptional silencing. We identified Miz-1 as a direct activator of WIF-1 transcriptional activity, which is found at WIF-1 promoter. In addition, we show that c-Myc contributes to WIF-1 transcriptional repression in a Miz-1-dependent manner. Although the transient repression mediated by Miz-1/c-Myc is independent of de novo methylation, the stable repression by this complex is associated with CpG island methylation of the critical -295 to -95-bp region of the WIF-1 promoter. Importantly, Miz-1 and c-Myc are found at WIF-1 promoter in WIF-1 non-expressing cell lines DLD-1 and 209myc. Transient knockdown or somatic knockout of c-Myc in DLD-1 failed to restore WIF-1 expression suggesting that c-Myc is involved in initiating rather than maintaining WIF-1 epigenetic silencing. In a genome-wide screen, DNAJA4, TGFβ-induced and TRIM59 were repressed by c-Myc overexpression and DNA promoter hypermethylation. Our data reveal novel insights into c-Myc-mediated DNA methylation-dependent transcriptional silencing, a mechanism that might contribute to the dysregulation of Wnt signaling in cancer.

Iliac artery injury following placement of the memotherm arterial stent

Iliac rupture and aneurysm formation at the site of stent placement has rarely been described in the literature. We report four cases, three of iliac rupture, including a delayed rupture, and an aneurysm, with the use of a single type of stent, the Memotherm stent. We believe the design of the stent significantly contributed to damage to the arterial wall and subsequently prevented closure of the arterial tear by balloon tamponade in the two cases where this was attempted. Two patients, one with rupture and one with an aneurysm, were successfully treated with a covered stent obviating surgery and two ruptures resulted in death. We recommend that all interventionists carrying out iliac angioplasty and/or stenting should have access to covered stents for such emergencies.

The influence of age, liver size and enantiomer concentrations on warfarin requirements

1. We have tested the hypothesis that the fall in hepatic mass with age influences the age related increase in sensitivity to warfarin. In 39 otherwise healthy outpatients, aged 50-87 years, stabilised on warfarin for prophylaxis of thromboembolism, age, mean International Normalised Ratio (INR), and mean warfarin dosage were recorded. Liver volume was measured by ultrasound, and plasma was assayed for trough concentrations of (R)- and (S)-warfarin. 2. There was a negative correlation between age and liver volume (r = -0.41; P = 0.01) and age and dose (r = -0.53; P = < 0.001) and a positive correlation between liver volume and dose (r = 0.49; P = 0.002). There was no significant correlation between dosage and (R)- and (S)-warfarin concentrations, nor between dosage and INR. 3. The regression model including both age and liver volume data showed a better fit for estimation of warfarin dosage requirement than regression models based on age and liver volume data alone. Ninety-five per cent prediction intervals for warfarin dose requirements were wide, whether age alone, or age and liver volume were used in calculations. 4. Due to inter-individual variation in warfarin dosage requirements related to other influences, both explained and unexplained, routine measurement of age and liver volume would not contribute further clinically useful information to that obtained by the INR test currently used for predicting warfarin dosage requirements.

Can intraductal breast carcinoma be excised completely by local excision? Clinical and pathologic predictors

BACKGROUND

Microscopic evaluation of excised intraductal breast carcinoma (DCIS) specimens using a serial subgross technique reveals that in many patients the lesion is larger than expected, often making complete excision impossible with less than a true quadrantectomy. Data is presented on 181 patients with DCIS in whom the initial biopsy was performed using a more cosmetic wide local excision rather than a true quadrantectomy.

METHODS

Clear margins were defined as no tumor within 1 mm of any inked or dyed margin. All of these patients subsequently underwent mastectomy or reexcision of the initial biopsy site. This allowed pathologic evaluation for residual disease.

RESULTS

At mastectomy or reexcision, 76% of patients with initially involved margins had residual DCIS, as did 43% of patients with initially clear margins (P < 0.0001). Larger tumor size was a statistically significant predictor of initial margin involvement and residual DCIS (P < 0.05). Patients with comedo-DCIS had a greater tendency toward positive initial histologic margins and residual DCIS, but this trend was not statistically significant (P < 0.1).

CONCLUSION

DCIS presents major problems to both surgeons and pathologists. It is difficult to excise completely using a wide local excision. Histologically negative margins do not guarantee that residual DCIS has not been left behind. Inadequate excision of the primary lesions may be the most important cause of local failure after conservative treatment for intraductal breast carcinoma.

Transfemoral digital subtraction aortography. Are diluted high osmolar contrast media acceptable?

The ionic monomer, sodium diatrizoate at 150 mg I/ml (726 mosmol/kg) and the non-ionic monomer, iopamidol, diluted to the same iodine concentration but at 324.3 mosmol/kg, were randomly allocated to patients undergoing transfemoral intra-arterial digital subtraction angiography for lower limb peripheral vascular disease. The agents produced images of comparable quality and diagnostic efficacy. There were no significant differences between the media regarding sensations of pain and warmth. Minor neurological symptoms (headache and dizziness) occurred 7 times more frequently with the ionic monomer. There was a slight but temporary rise in plasma potassium one hour after injection of the ionic monomer but no evidence of appreciable intravascular haemolysis. The non-ionic monomer caused a slight fall in haemoglobin and haematocrit one hour after injection which is attributed to osmotic haemodilution. It is concluded that a diluted high osmolar contrast agent is an acceptable alternative to a low osmolar agent in transfemoral digital subtraction lower limb aortography.

Knowledge management as a decision support method: a diagnostic workup strategy application

We have explored the potential of a computer-based approach called "knowledge management" to aid in clinical problem solving and education. The major features of the approach are its ability to support flexible and immediate access by a user to relevant knowledge and annotation and organization of the knowledge for personal use and subsequent retrieval. We illustrate this approach with its application to diagnostic workup strategy problems. In this application, knowledge may be in the form of static narrative text, diagrams, pictures, graphs, tables, flow charts, or bibliographic citations. Other more dynamic forms of knowledge may be the result of simulations, "what if" analyses or modeling, quantitative mathematical or statistical calculation, or heuristic inference. User assessment has demonstrated the system's ease of use and user perception of its desirability, but underscores the need for a "critical mass" of knowledge before such an approach will be widely utilized.

Basal, sham feed and pentagastrin stimulated gastric acid, pepsin and electrolytes after omeprazole 20 mg and 40 mg daily

Gastric secretion was measured in nine patients with duodenal ulcer before, and after treatment for four weeks with omeprazole 20 mg or 40 mg daily. Basal acidity and acid output were affected variably by 20 mg, but inhibited totally by 40 mg daily. Sham feed stimulated acid output was reduced by 20 mg daily and completely inhibited by 40 mg daily. Maximal pentagastrin stimulated acid output was halved by 20 mg omeprazole daily and 84% inhibited by 40 mg daily. The reduction in acidity was always greater than the reduction of volume. Pepsin output after pentagastrin was little altered but with the reduced secretory volume pepsin concentrations were increased by both doses. The major cause of reduced aspirate acid output after omeprazole is decreased secretion of the primary acid component of the parietal cell by the proton pump H+K+ ATPase. Duodenogastric alkaline reflux is, however, markedly increased after omeprazole and is an additional factor in the resultant hypoacidity or even anacidity after this drug.