Sex modulates the diet-induced changes to the plasma lipidome in a rat model of cardiorespiratory fitness

OBJECTIVE

Individuals with higher intrinsic cardiorespiratory fitness (CRF) experience decreased rates of cardiometabolic disease and mortality, and high CRF is associated with increased utilization of fatty acids (FAs) for energy. Studies suggest a complex relationship between CRF, diet, and sex with health outcomes, but this interaction is understudied. We hypothesized that FA utilization differences by fitness and sex could be detected in the plasma metabolome when rats or humans were fed a high carbohydrate (HC) or high fat (HF) diet.

METHODS

Male and female rats selectively bred for low (LCR) and high (HCR) CRF were fed a chow diet or a sucrose-free HF (45 % fat) or HC (10 % fat) diet. Plasma samples were collected at days 0, 3, and 14. Human plasma data was collected from male and female participants who were randomized into a HC or HF diet for 21 days. Samples were analyzed using liquid chromatography-mass spectrometry and regression statistics were used to quantify the effect of diet, CRF, and sex on the lipidome.

RESULTS

In rats, the baseline lipidome is more significantly influenced by sex than by CRF, especially as elevated diglycerides, triglycerides, phosphatidylcholines, and lysophosphatidylcholines in males. A dynamic response to diet was observed 3 days after diet, but after 14 days of either diet, the lipidome was modulated by sex with a larger effect size than by diet. Data from the human study also suggests a sex-dependent response to diet with opposite directionality of affect compared to rats, highlighting species-dependent responses to dietary intervention.

Utilizing the Glucose and Insulin Response Shape of an Oral Glucose Tolerance Test to Predict Dysglycemia in Children with Overweight and Obesity, Ages 8-18 Years

Common dysglycemia measurements including fasting plasma glucose (FPG), oral glucose tolerance test (OGTT)-derived 2 h plasma glucose, and hemoglobin A1c (HbA1c) have limitations for children. Dynamic OGTT glucose and insulin responses may better reflect underlying physiology. This analysis assessed glucose and insulin curve shapes utilizing classifications-biphasic, monophasic, or monotonically increasing-and functional principal components (FPCs) to predict future dysglycemia. The prospective cohort included 671 participants with no previous diabetes diagnosis (BMI percentile ≥ 85th, 8-18 years old); 193 returned for follow-up (median 14.5 months). Blood was collected every 30 min during the 2 h OGTT. Functional data analysis was performed on curves summarizing glucose and insulin responses. FPCs described variation in curve height (FPC1), time of peak (FPC2), and oscillation (FPC3). At baseline, both glucose and insulin FPC1 were significantly correlated with BMI percentile (Spearman correlation r = 0.22 and 0.48), triglycerides (r = 0.30 and 0.39), and HbA1c (r = 0.25 and 0.17). In longitudinal logistic regression analyses, glucose and insulin FPCs predicted future dysglycemia (AUC = 0.80) better than shape classifications (AUC = 0.69), HbA1c (AUC = 0.72), or FPG (AUC = 0.50). Further research should evaluate the utility of FPCs to predict metabolic diseases.

metabCombiner 2.0: Disparate Multi-Dataset Feature Alignment for LC-MS Metabolomics

Liquid chromatography-high-resolution mass spectrometry (LC-HRMS), as applied to untargeted metabolomics, enables the simultaneous detection of thousands of small molecules, generating complex datasets. Alignment is a crucial step in data processing pipelines, whereby LC-MS features derived from common ions are assembled into a unified matrix amenable to further analysis. Variability in the analytical factors that influence liquid chromatography separations complicates data alignment. This is prominent when aligning data acquired in different laboratories, generated using non-identical instruments, or between batches from large-scale studies. Previously, we developed metabCombiner for aligning disparately acquired LC-MS metabolomics datasets. Here, we report significant upgrades to metabCombiner that enable the stepwise alignment of multiple untargeted LC-MS metabolomics datasets, facilitating inter-laboratory reproducibility studies. To accomplish this, a "primary" feature list is used as a template for matching compounds in "target" feature lists. We demonstrate this workflow by aligning four lipidomics datasets from core laboratories generated using each institution's in-house LC-MS instrumentation and methods. We also introduce batchCombine, an application of the metabCombiner framework for aligning experiments composed of multiple batches. metabCombiner is available as an R package on Github and Bioconductor, along with a new online version implemented as an R Shiny App.

Comparing Self-Reported Dietary Intake to Provided Diet during a Randomized Controlled Feeding Intervention: A Pilot Study

Systematic and random errors based on self-reported diet may bias estimates of dietary intake. The objective of this pilot study was to describe errors in self-reported dietary intake by comparing 24 h dietary recalls to provided menu items in a controlled feeding study. This feeding study was a parallel randomized block design consisting of a standard diet (STD; 15% protein, 50% carbohydrate, 35% fat) followed by either a high-fat (HF; 15% protein, 25% carbohydrate, 60% fat) or a high-carbohydrate (HC; 15% protein, 75% carbohydrate, 10% fat) diet. During the intervention, participants reported dietary intake in 24 h recalls. Participants included 12 males (seven HC, five HF) and 12 females (six HC, six HF). The Nutrition Data System for Research was utilized to quantify energy, macronutrients, and serving size of food groups. Statistical analyses assessed differences in 24 h dietary recalls vs. provided menu items, considering intervention type (STD vs. HF vs. HC) (Student's t-test). Caloric intake was consistent between self-reported intake and provided meals. Participants in the HF diet underreported energy-adjusted dietary fat and participants in the HC diet underreported energy-adjusted dietary carbohydrates. Energy-adjusted protein intake was overreported in each dietary intervention, specifically overreporting beef and poultry. Classifying misreported dietary components can lead to strategies to mitigate self-report errors for accurate dietary assessment.

The Influence of Maternal High Fat Diet During Lactation on Offspring Hematopoietic Priming

Obesity and metabolic diseases are rising among women of reproductive age, increasing offspring metabolic risk. Maternal nutritional interventions during lactation present an opportunity to modify offspring outcomes. We previously demonstrated in mice that adult male offspring have metabolic impairments and increased adipose tissue macrophages (ATM) when dams are fed high fat diet (HFD) during the postnatal lactation window (HFD PN). We sought to understand the effect of HFD during lactation on early-life inflammation. HFD PN offspring were evaluated at postnatal day 16 to 19 for tissue weight and gene expression. Profiling of adipose tissue and bone marrow immune cells was conducted through lipidomics, in vitro myeloid colony forming unit assays, and flow cytometry. HFD PN mice had more visceral gonadal white adipose tissue (GWAT) and subcutaneous fat. Adipose tissue RNA sequencing demonstrated enrichment of inflammation, chemotaxis, and fatty acid metabolism and concordant changes in GWAT lipidomics. Bone marrow (BM) of both HFD PN male and female offspring had increased monocytes (CD45+Ly6G-CD11b+CD115+) and B cells (CD45+Ly6G-CD11b-CD19+). Similarly, serum from HFD PN offspring enhanced in vitro BM myeloid colonies in a toll-like receptor 4-dependent manner. We identified that male HFD PN offspring had increased GWAT pro-inflammatory CD11c+ ATMs (CD45+CD64+). Maternal exposure to HFD alters milk lipids enhancing adiposity and myeloid inflammation even in early life. Future studies are needed to understand the mechanisms driving this pro-inflammatory state of both BM and ATMs, the causes of the sexually dimorphic phenotypes, and the feasibility of intervening in this window to improve metabolic health.

Prospective Test Performance of Nonfasting Biomarkers to Identify Dysglycemia in Children and Adolescents

INTRODUCTION

Test performance screening measures for dysglycemia have not been evaluated prospectively in youth. This study evaluated the prospective test performance of random glucose (RG), 1-h nonfasting glucose challenge test (1-h GCT), hemoglobin A1c (HbA1c), fructosamine (FA), and 1,5-anhydroglucitol (1,5-AG) for identifying dysglycemia.

METHODS

Youth ages 8-17 years with overweight or obesity (body mass index, BMI, ≥85th percentile) without known diabetes completed nonfasting tests at baseline (n = 176) and returned an average of 1.1 years later for two formal fasting 2-h oral glucose tolerance tests. Outcomes included glucose-defined dysglycemia (fasting plasma glucose ≥100 mg/dL or 2-h plasma glucose ≥140 mg/dL) or elevated HbA1c (≥5.7%). Longitudinal test performance was evaluated using receiver-operating characteristic (ROC) curves and calculation of area under the curve (AUC).

RESULTS

Glucose-defined dysglycemia, elevated HbA1c, and either dysglycemia or elevated HbA1c were present in 15 (8.5%), 11 (6.3%), and 23 (13.1%) participants at baseline, and 16 (9.1%), 18 (10.3%), and 28 (15.9%) participants at follow-up. For prediction of glucose-defined dysglycemia at follow-up, RG, 1-h GCT, and HbA1c had similar performance (0.68 (95% CI: 0.55-0.80), 0.76 (95% CI: 0.64-0.89), and 0.70 (95% CI: 0.56-0.84)), while FA and 1,5-AG performed poorly. For prediction of HbA1c at follow-up, baseline HbA1c had strong performance (AUC 0.93 [95% CI: 0.88-0.98]), RG had moderate performance (AUC 0.67 [95% CI: 0.54-0.79]), while 1-h GCT, FA, and 1,5-AG performed poorly.

CONCLUSION

HbA1c and nonfasting glucose tests had reasonable longitudinal discrimination identifying adolescents at risk for dysglycemia, but performance depended on outcome definition.

Alterations in Fecal Short-Chain Fatty Acids after Bariatric Surgery: Relationship with Dietary Intake and Weight Loss

Bariatric surgery is associated with weight loss attributed to reduced caloric intake, mechanical changes, and alterations in gut hormones. However, some studies have suggested a heightened incidence of colorectal cancer (CRC) has been associated with bariatric surgery, emphasizing the importance of identifying mechanisms of risk. The objective of this study was to determine if bariatric surgery is associated with decreases in fecal short-chain fatty acids (SCFA), a group of bacterial metabolites of fiber. Fecal samples (n = 22) were collected pre- (~6 weeks) and post-bariatric surgery (~4 months) in patients undergoing Roux-en-Y gastric bypass and sleeve gastrectomy. SCFA levels were quantified using liquid chromatography/mass spectrometry. Dietary intake was quantified using 24-h dietary recalls. Using an aggregate variable, straight SCFAs significantly decreased by 27% from pre- to post-surgery, specifically acetate, propionate, butyrate, and valerate. Pre-surgery weight was inversely associated with butyrate, with no association remaining post-surgery. Multiple food groups were positively (sugars, milk, and red and orange vegetables) and inversely (animal protein) associated with SCFA levels. Our results suggest a potential mechanism linking dietary intake and SCFA levels with CRC risk post-bariatric surgery with implications for interventions to increase SCFA levels.

Trimester-specific phthalate exposures in pregnancy are associated with circulating metabolites in children

Background

Prenatal phthalates exposures have been related to adiposity in peripuberty in a sex-specific fashion. Untargeted metabolomics analysis to assess circulating metabolites offers the potential to characterize biochemical pathways by which early life exposures influence the development of cardiometabolic risk during childhood and adolescence, prior to becoming evident in clinical markers.

Methods

Among mother-child dyads from the Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) birth cohort, we measured 9 phthalate metabolites and bisphenol A in maternal spot urine samples obtained during each trimester of pregnancy, corrected for urinary specific gravity and natural log-transformed. In 110 boys and 124 girls aged 8–14 years, we used a mass-spectrometry based untargeted metabolomics platform to measure fasting serum metabolites, yielding 572 annotated metabolites. We estimated the associations between trimester-specific urinary toxicants and each serum metabolite, among all children or stratified by sex and adjusting for child age, BMI z-score, and pubertal onset. We accounted for multiple comparisons using a 10% false discovery rate (q<0.1).

Results

Associations between exposures and metabolites were observed among all children and in sex-stratified analyses (q<0.1). First trimester MEP, MiBP, and MCPP were associated with decreased 2-deoxy-D-glucose among all children. Among girls, third trimester concentrations of MECPP, MEHHP, MEHP, and MCPP were associated with 15, 13, 1, and 10 metabolites, respectively, including decreased choline and increased acylcarnitines and saturated FAs (FA). Among boys, third trimester MIBP was positively associated with 9 features including long chain saturated FAs, and second trimester MBzP was inversely associated with thyroxine.

Conclusions

Metabolomics biomarkers may reflect sex- and exposure timing-specific responses to prenatal phthalate exposures manifesting in childhood that may not be detected using standard clinical markers of cardiometabolic risk.

Metabolomics reveals sex-specific pathways associated with changes in adiposity and muscle mass in a cohort of Mexican adolescents

BACKGROUND

Alterations in body composition (BC) during adolescence relates to future metabolic risk, yet underlying mechanisms remain unclear.

OBJECTIVES

To assess the association between the metabolome with changes in adiposity (body mass index [BMI], waist circumference [WC], triceps skinfold [TS], fat percentage [BF%]) and muscle mass (MM).

METHODS

In Mexican adolescents (n = 352), untargeted serum metabolomics was profiled at baseline. and data were reduced by pairing hierarchical clustering with confirmatory factor analysis, yielding 30 clusters with 51 singleton metabolites. At the baseline and follow-up visits (1.6-3.5 years apart), anthropometry was collected to identify associations between baseline metabolite clusters and change in BC (∆) using seemingly unrelated and linear regression.

RESULTS

Between visits, MM increased in boys and adiposity increased in girls. Sex differences were observed between metabolite clusters and changes in BC. In boys, aromatic amino acids (AAA), branched chain amino acids (BCAA) and fatty acid oxidation metabolites were associated with increases in ∆BMI, and ∆BF%. Phospholipids were associated with decreases in ∆TS and ∆MM. Negative associations were observed for ∆MM in boys with a cluster including AAA and BCAA, whereas positive associations were found for a cluster containing tryptophan metabolites. Few associations were observed between metabolites and BC change in girls, with one cluster comprising methionine, proline and lipids associated with decreases in ∆BMI, ∆WC and ∆MM.

CONCLUSION

Sex-specific associations between the metabolome and change in BC were observed, highlighting metabolic pathways underlying adolescent physical growth.

Effect of enprostil on serum gastrin and pepsinogen A and C levels in patients on long-term treatment with omeprazole

BACKGROUND

Treatment of omeprazole induces profound inhibition of gastric acid secretion, resulting in hypergastrinaemia. In rats hypergastrinaemia induced by chronic administration of high doses of omeprazole resulted in ECL-cell hyperplasia and subsequent carcinoid formation. This finding may limit long-term therapy in man. The synthetic prostaglandin E2 analogue enprostil not only inhibits gastric acid secretion but also reduces serum gastrin in normal subjects and in peptic ulcer patients. The present study was undertaken to determine whether enprostil reduces serum gastrin in patients on long-term treatment with omeprazole.

METHODS

Eight patients with reflux oesophagitis treated with 40 mg omeprazole once daily for at least 3 months received 35 micrograms enprostil t.d.s. during a 5-day treatment course. Basal and postprandial serum gastrin concentrations and pepsinogen A and C levels were measured on the day before, the first and the final day, and on the day after cessation of treatment.

RESULTS

Enprostil significantly (P < 0.05) reduced basal serum gastrin from 65 +/- 15 pmol/L to 51 +/- 13 pmol/L on the first treatment day, and to 41 +/- 9 pmol/L on the final day. Enprostil also significantly (P < 0.05) reduced postprandial integrated serum gastrin from 6173 +/- 849 pmol.h/L to 4516 +/- 906 pmol.h/L and to 3532 +/- 706 pmol.h/L on the first and final treatment days, respectively. On the day after cessation of treatment basal (57 +/- 11 pmol/L) and postprandial integrated serum gastrin concentrations (5766 +/- 864 pmol.h/L) were not significantly different when compared to pretreatment values. Enprostil had no significant influence on serum pepsinogens A and C.

CONCLUSION

Short-term co-administration of enprostil lowers the serum gastrin levels in patients on long-term treatment with omeprazole.

Effect of synthetic prostaglandin E2 analog enprostil on omeprazole-induced hypergastrinemia and hyperpepsinogenemia

This study was undertaken to determine whether the synthetic prostaglandin E2 analog enprostil is able to inhibit basal and postprandial hypergastrinemia induced by omeprazole. We also studied the effect of omeprazole, enprostil, and the combination of both drugs on serum pepsinogen A and C levels. Eight normal subjects received in random order five-day courses of 40 mg omeprazole once a day, 35 micrograms enprostil three times a day, the combination of both drugs, and placebo. Omeprazole induced significant increases in basal and postprandial serum gastrin and in pepsinogen A and C levels. These increments persisted on the day after stopping treatment. Coadministration of enprostil inhibited omeprazole-induced basal hypergastrinemia and postprandial integrated serum gastrin, but not basal serum pepsinogen A and C, while the inhibition on the day after the treatment courses only reached statistical significance for the postprandial integrated serum gastrin concentration. It is concluded that enprostil inhibits omeprazole-induced basal and postprandial hypergastrinemia, with a tendency to protracted inhibition after stopping the drugs, and that enprostil does not significantly influence omeprazole-induced increases in pepsinogen A and C level. Coadministration of enprostil may be helpful in preventing pronounced hypergastrinemia in the few patients who show large serum gastrin increases during treatment with omeprazole.

Inhibition of omeprazole induced hypergastrinaemia by SMS 201-995, a long acting somatostatin analogue in man

Whether the long acting somatostatin analogue SMS 201-995 (octreotide, Sandostatin) could inhibit the basal and meal stimulated hypergastrinaemia and hyperpepsinogenaemia induced by omeprazole was investigated. Eight healthy subjects were randomised to receive five day courses of SMS 201-995 (25 micrograms subcutaneously three times daily), omeprazole (40 mg once a day), a combination of both drugs, or placebo. Basal and meal stimulated serum gastrin and basal serum pepsinogen A and C values were measured the day before treatment, on day five of treatment, and the day after each course of treatment. Omeprazole caused significant increases in basal and meal stimulated peak and integrated serum gastrin values and pepsinogen A and C levels, which were still significantly raised the day after stopping omeprazole treatment. Giving SMS 201-995 with omeprazole significantly reduced any omeprazole induced increases in basal and meal stimulated peak and integrated serum gastrin levels; serum pepsinogen A and C values were significantly inhibited too. Serum gastrin values during combined therapy were not significantly different from those during placebo treatment, whereas pepsinogen A and C levels were still significantly raised. On the day after stopping combined therapy, basal and meal stimulated peak and integrated serum gastrin and serum pepsinogen C (but not pepsinogen A) levels were not significantly different from values obtained on the day after stopping omeprazole alone. SMS 201-995 without omeprazole significantly inhibited basal and meal stimulated peak and integrated serum gastrin levels. Pepsinogen A was also significantly inhibited by SMS 210-995, but the reduction in pepsinogen C failed to reach statistical significance. In conclusion, SMS 201-995 prevents basal and meal stimulated increases in serum gastrin during omeprazole therapy. This finding may have clinical importance in the few patients who have pronounced hypergastrinaemia because of profound long acting acid inhibition.

Attenuation of the gastric acid and serum gastrin-lowering effects of the prostaglandin E2 analog enprostil

Enprostil, a synthetic prostaglandin E2 analog, has been shown to decrease gastric acid secretion and plasma gastrin levels during short-term treatment. However, effects of prolonged treatment with enprostil on these parameters in humans are unknown. We have studied the effects of 35 micrograms enprostil twice daily on 24-hour intragastric pH, basal gastrin, and meal-stimulated gastrin release in 10 healthy volunteers. Enprostil, 35 micrograms, was ingested twice daily for 4 weeks. Subjects were studied on day 0 (preentry) and days 1 and 29, when enprostil was taken 30 minutes before the first and third standard test meals at 9 AM and 5 PM. Enprostil significantly increased 24-hour median pH (p < 0.02) on day 1 but not on day 29. Enprostil had no significant effect on basal gastrin levels compared with placebo. However, on day 1, but not on day 29, postprandial gastrin levels were significantly lower compared with preentry (p < 0.05). On day 29 post-prandial gastrin levels after the second standard test meal were significantly higher compared with preentry data (p < 0.05). In conclusion, 35 micrograms enprostil twice daily reduced gastric acidity and serum gastrin levels on the first day of treatment, but this effect attenuated and even transiently reversed during a 4-week treatment period.

Effect of short-term administration of omeprazole on serum gastrin and pepsinogens in antrectomized patients

Omeprazole, a potent and long-acting inhibitor of gastric acid secretion, is known to increase both serum gastrin and pepsinogen A and C levels in unoperated subjects. It has been suggested that the rise in serum pepsinogens is mediated by the omeprazole-induced increase in serum gastrin. This study was undertaken to determine the role of gastrin in hyper-pepsinogenemia induced by antisecretory therapy. We have studied the effect of a 5-day course of 40 mg of omeprazole daily on fasting serum gastrin and pepsinogen A and C levels in 14 patients with an antrectomy and a Billroth I anastomosis (n = 8) or a Billroth II anastomosis (n = 6). In antrectomized patients omeprazole failed to induce any increase in basal serum gastrin. On the other hand, omeprazole increased significantly serum pepsinogen A levels in both Billroth I and II patients, while the rise in serum pepsinogen C level was significant in Billroth I, but just failed to reach statistical significance in Billroth II patients. We conclude that the stimulation of serum pepsinogens A and C by a short-term treatment with omeprazole is not mediated by increases in serum gastrin. This study further shows that omeprazole stimulates gastrin release only from the antrum and not from extra-antral sources.

IgG subclass response to Helicobacter pylori in patients with chronic active gastritis and duodenal ulcer

The IgG subclass response is determined by the type of bacteria producing the infection and by genetic factors of the host. Patients with a Helicobacter pylori infection develop a specific immune response that is mainly of the IgA and IgG class. We measured the IgG subclass response in 20 patients with chronic active gastritis without a history of duodenal ulcer and 20 patients with chronic active gastritis and duodenal ulcer diagnosed by endoscopy and histology. A control group included 20 H. pylori-negative patients and 60 H. pylori-positive blood transfusion donors. Systemic IgG subclass response was measured with a modified enzyme-linked immunosorbent assay technique, using as antigen a sonicate of six different H. pylori strains. Mouse monoclonal antibodies against each of the four human IgG subclasses (IgG1, IgG2, IgG3, and IgG4) were used. The total IgG anti-H. pylori antibody titres were equal in all three H. pylori-positive groups and significantly different from that of the negative control group (p less than 0.01). The IgG subclass response in persons infected with H. pylori involved all four subclasses but was predominantly of the IgG1 and IgG2 subclasses. All of the groups with H. pylori infection had significantly higher levels of IgG1 than the negative control group, but no differences were detected among the three groups. However, the duodenal ulcer group had a significantly higher IgG2 response than the gastritis group (mean optical density +/- SEM, 0.382 +/- 0.047 versus 0.200 +/- 0.025, respectively; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Long term serological surveillance after treatment of Helicobacter pylori infection

Fifteen patients with type B gastritis caused by Helicobacter pylori infection were treated with 'triple' therapy consisting of colloidal bismuth subcitrate, amoxycillin, and metronidazole. All were followed up as outpatients every three months for at least one year. After 'triple' therapy a significant (p less than 0.01) and persistent reduction in IgA and IgG antibody levels against H pylori was detected. In three patients recurrent active infection with H pylori at nine and 12 months was detected by a rise in IgA (three patients) and IgG (two patients) antibody levels against H pylori and worsening of symptoms, and was confirmed by culture and histology. In 11 patients, the absence of infection at 12 months was confirmed by culture and histology. In a control group of 13 patients with type B gastritis who received no antibacterial treatment, specific IgA and IgG antibody levels against H pylori remained unchanged during 12 months of follow up. Although specific IgG against H pylori is the most widely used serological test for screening, our data indicate that specific IgA is also valuable in monitoring treatment. These serological tests are easy to perform, relatively inexpensive, devoid of radioactivity and are very acceptable to patients. It is concluded that serological testing is the preferred method for follow up after treatment for H pylori infection and will probably replace endoscopy or the urea breath test.

Omeprazole in the treatment of Zollinger-Ellison syndrome and histamine H2-antagonist refractory ulcers

Omeprazole is a very potent and long-acting inhibitor of gastric acid secretion. These characteristics make the drug very suitable for the management of gastric acid hypersecretion and symptom relief in patients with the Zollinger-Ellison syndrome, and in the treatment of patients with ulcers resistant to histamine H2-receptor antagonists. Most patients require only a once-daily dose, whereas in about 30% of patients with Zollinger-Ellison syndrome the dose has to be split. During long-term treatment the required dose of omeprazole is usually rather stable. Up until now neither in patients with Zollinger-Ellison syndrome nor in those with resistant ulcers have convincing reports of resistance to omeprazole been published. However, a relative disadvantage of omeprazole is the observation that symptom-free Zollinger-Ellison syndrome patients are less inclined to undergo the work-up for surgery, which is the only possible curative treatment for these patients. Omeprazole therapy has been well tolerated and no side effects, significant changes in laboratory variables or toxicity have been noted.

Improved specificity of the PABA test with p-aminosalicylic acid (PAS)

Until now use of the PABA test together with [14C] PABA to calculate the PABA excretion index has probably been the best adaptation suggested to enhance the specificity of this non-invasive pancreatic function test. Drawbacks of the method are the application of radioactivity, the fact that children, pregnant women, and patients with renal insufficiency have to be excluded from the test, and the possible interference of drugs and isotopes. We propose simultaneous administration of p-aminosalicylic acid (PAS) in the PABA test and quantification of the urinary PABA and PAS excretion with liquid chromatography. Urinary PABA and PAS excretion in six hours are comparable (69.5 +/- 8.4% and 65.6 +/- 18.4% respectively in five healthy volunteers). Application of the PABA/PAS ratio was compared with the urinary PABA excretion in 21 normal controls, 38 patients with pancreatic disease, and 42 patients without pancreatic pathology. The PABA/PAS ratio and the per cent PABA excretion correlated very well in pancreatic patients: (PABA/PAS ratio) = 0.0149 (% PABA) + 0.052 (r = 0.902). Use of the PABA/PAS ratio enhanced the specificity of the test from 76 to 89%.

Captopril plus hydrochlorothiazide once daily normalizes 24 h blood pressure in patients with essential hypertension

The hypotensive effect of captopril 50 mg twice daily and of captopril 50 mg + hydrochlorothiazide (HCTZ) 25 mg once daily was studied in 12 patients with mild to moderate essential hypertension, whose blood pressure was not normalized by captopril 25 mg twice daily alone. Both captopril 50 mg twice daily and captopril 50 mg + HCTZ 25 mg once daily caused a significant reduction of outpatient blood pressures as compared with placebo (P less than 0.001). Captopril 50 mg + HCTZ 25 mg once daily also reduced outpatient blood pressures significantly when compared with captopril 25 mg twice daily (P less than 0.01). Both captopril 50 mg twice daily and captopril 50 mg + HCTZ 25 mg once daily significantly reduced 24 h blood pressure (P less than 0.001) without disturbance of its normal circadian rhythm. This effect was more pronounced while on captopril + HCTZ. Captopril 50 mg + HCTZ 25 mg once daily normalizes 24 h blood pressure in most patients with mild to moderate essential hypertension, whose blood pressure is not controlled by captopril 25 mg twice daily alone.

[A comparison of 3 isolation methods for the demonstration of Salmonella bacteria in fryer-chicken feed]

167 Samples of fryer chicken feed were examined for the presence of Salmonella using three different methods of isolation. These methods consisted in the isolation of Salmonella using procedure ISO-3565, this method but supplemented by treatment with hydrogen sulphide (ISO + H2S) and the membrane filter disc immuno-immobilisation method (MFDI). In addition, thirty-three samples were examined by the ISO and ISO + H2S techniques. 200 Grams of feed of each sample were studied. A total number of fifteen samples (7.5 per cent) were found to be positive for Salmonella, thirteen of which were examined by the ISO-3565 method of isolation of Salmonella. When the other methods were employed, only five samples were found to be positive for Salmonella using the ISO + H2S technique and two using the MFDI method. When all three methods were used, they failed to produce positive results in each sample which had been found to be positive for Salmonella. The differences in the number of positive samples were found to be significantly (P less than 0.01) in favour of the ISO method. When a choice has to be made between the method used in the detection of Salmonella, the ISO-3565 method of isolating Salmonella is to be preferred.