The effect of aspirin and eicosapentaenoic acid on urinary biomarkers of prostaglandin E2 synthesis and platelet activation in participants of the seAFOod polyp prevention trial

Urinary prostaglandin (PG) E metabolite (PGE-M) and 11-dehydro (d)-thromboxane (TX) B2 are biomarkers of cyclooxygenase-dependent prostanoid synthesis. We investigated (1) the effect of aspirin 300 mg daily and eicosapentaenoic acid (EPA) 2000 mg daily, alone and in combination, on urinary biomarker levels and, (2) whether urinary biomarker levels predicted colorectal polyp risk, during participation in the seAFOod polyp prevention trial. Urinary PGE-M and 11-d-TXB2 were measured by liquid chromatography-tandem mass spectrometry. The relationship between urinary biomarker levels and colorectal polyp outcomes was investigated using negative binomial (polyp number) and logistic (% with one or more polyps) regression models. Despite wide temporal variability in PGE-M and 11-d-TXB2 levels within individuals, both aspirin and, to a lesser extent, EPA decreased levels of both biomarkers (74% [P ≤ .001] and 8% [P ≤ .05] reduction in median 11-d-TXB2 values, respectively). In the placebo group, a high (quartile [Q] 2-4) baseline 11-d-TXB2 level predicted increased polyp number (incidence rate ratio [IRR] [95% CI] 2.26 [1.11,4.58]) and risk (odds ratio [95% CI] 3.56 [1.09,11.63]). A low (Q1) on-treatment 11-d-TXB2 level predicted reduced colorectal polyp number compared to placebo (IRR 0.34 [0.12,0.93] for combination aspirin and EPA treatment) compared to high on-treatment 11-d-TXB2 values (0.61 [0.34,1.11]). Aspirin and EPA both inhibit PGE-M and 11-d-TXB2 synthesis in keeping with shared in vivo cyclooxygenase inhibition. Colorectal polyp risk and treatment response prediction by 11-d-TXB2 is consistent with a role for platelet activation during early colorectal carcinogenesis. The use of urinary 11-d-TXB2 measurement for a precision approach to colorectal cancer risk prediction and chemoprevention requires prospective evaluation.

Polymorphisms in Cyclooxygenase, Lipoxygenase, and TP53 Genes Predict Colorectal Polyp Risk Reduction by Aspirin in the seAFOod Polyp Prevention Trial

Aspirin and eicosapentaenoic acid (EPA) reduce colorectal adenomatous polyp risk and affect synthesis of oxylipins including prostaglandin E2. We investigated whether 35 SNPs in oxylipin metabolism genes such as cyclooxygenase (PTGS) and lipoxygenase (ALOX), as well as 7 SNPs already associated with colorectal cancer risk reduction by aspirin (e.g., TP53; rs104522), modified the effects of aspirin and EPA on colorectal polyp recurrence in the randomized 2 × 2 factorial seAFOod trial. Treatment effects were reported as the incidence rate ratio (IRR) and 95% confidence interval (CI) by stratifying negative binomial and Poisson regression analyses of colorectal polyp risk on SNP genotype. Statistical significance was reported with adjustment for the false discovery rate as the P and q value. 542 (of 707) trial participants had both genotype and colonoscopy outcome data. Reduction in colorectal polyp risk in aspirin users compared with nonaspirin users was restricted to rs4837960 (PTGS1) common homozygotes [IRR, 0.69; 95% confidence interval (CI), 0.53-0.90); q = 0.06], rs2745557 (PTGS2) compound heterozygote-rare homozygotes [IRR, 0.60 (0.41-0.88); q = 0.06], rs7090328 (ALOX5) rare homozygotes [IRR 0.27 (0.11-0.64); q = 0.05], rs2073438 (ALOX12) common homozygotes [IRR, 0.57 (0.41-0.80); q = 0.05], and rs104522 (TP53) rare homozygotes [IRR, 0.37 (0.17-0.79); q = 0.06]. No modification of colorectal polyp risk in EPA users was observed. In conclusion, genetic variants relevant to the proposed mechanism of action on oxylipins are associated with differential colorectal polyp risk reduction by aspirin in individuals who develop multiple colorectal polyps. SNP genotypes should be considered during development of personalized, predictive models of colorectal cancer chemoprevention by aspirin.

PREVENTION RELEVANCE

Single-nucleotide polymorphisms in genes controlling lipid mediator signaling may modify the colorectal polyp prevention activity of aspirin. Further investigation is required to determine whether testing for genetic variants can be used to target cancer chemoprevention by aspirin to those who will benefit most.

Metabolomic epidemiology offers insights into disease aetiology

Metabolomic epidemiology is the high-throughput study of the relationship between metabolites and health-related traits. This emerging and rapidly growing field has improved our understanding of disease aetiology and contributed to advances in precision medicine. As the field continues to develop, metabolomic epidemiology could lead to the discovery of diagnostic biomarkers predictive of disease risk, aiding in earlier disease detection and better prognosis. In this Review, we discuss key advances facilitated by the field of metabolomic epidemiology for a range of conditions, including cardiometabolic diseases, cancer, Alzheimer's disease and COVID-19, with a focus on potential clinical utility. Core principles in metabolomic epidemiology, including study design, causal inference methods and multi-omic integration, are briefly discussed. Future directions required for clinical translation of metabolomic epidemiology findings are summarized, emphasizing public health implications. Further work is needed to establish which metabolites reproducibly improve clinical risk prediction in diverse populations and are causally related to disease progression.

An epidemiological introduction to human metabolomic investigations

Metabolomics holds great promise for uncovering insights around biological processes impacting disease in human epidemiological studies. Metabolites can be measured across biological samples, including plasma, serum, saliva, urine, stool, and whole organs and tissues, offering a means to characterize metabolic processes relevant to disease etiology and traits of interest. Metabolomic epidemiology studies face unique challenges, such as identifying metabolites from targeted and untargeted assays, defining standards for quality control, harmonizing results across platforms that often capture different metabolites, and developing statistical methods for high-dimensional and correlated metabolomic data. In this review, we introduce metabolomic epidemiology to the broader scientific community, discuss opportunities and challenges presented by these studies, and highlight emerging innovations that hold promise to uncover new biological insights.

Metabolic drivers of dysglycemia in pregnancy: ethnic-specific GWAS of 146 metabolites and 1-sample Mendelian randomization analyses in a UK multi-ethnic birth cohort

Introduction

Gestational diabetes mellitus (GDM) is the most common pregnancy complication worldwide and is associated with short- and long-term health implications for both mother and child. Prevalence of GDM varies between ethnicities, with South Asians (SAs) experiencing up to three times the risk compared to white Europeans (WEs). Recent evidence suggests that underlying metabolic difference contribute to this disparity, but an investigation of causality is required.

Methods

To address this, we paired metabolite and genomic data to evaluate the causal effect of 146 distinct metabolic characteristics on gestational dysglycemia in SAs and WEs. First, we performed 292 GWASs to identify ethnic-specific genetic variants associated with each metabolite (P ≤ 1 x 10-5) in the Born and Bradford cohort (3688 SA and 3354 WE women). Following this, a one-sample Mendelian Randomisation (MR) approach was applied for each metabolite against fasting glucose and 2-hr post glucose at 26-28 weeks gestation. Additional GWAS and MR on 22 composite measures of metabolite classes were also conducted.

Results

This study identified 15 novel genome-wide significant (GWS) SNPs associated with tyrosine in the FOXN and SLC13A2 genes and 1 novel GWS SNP (currently in no known gene) associated with acetate in SAs. Using MR approach, 14 metabolites were found to be associated with postprandial glucose in WEs, while in SAs a distinct panel of 11 metabolites were identified. Interestingly, in WEs, cholesterols were the dominant metabolite class driving with dysglycemia, while in SAs saturated fatty acids and total fatty acids were most commonly associated with dysglycemia.

Discussion

In summary, we confirm and demonstrate the presence of ethnic-specific causal relationships between metabolites and dysglycemia in mid-pregnancy in a UK population of SA and WE pregnant women. Future work will aim to investigate their biological mechanisms on dysglycemia and translating this work towards ethnically tailored GDM prevention strategies.

Plasma and rectal mucosal oxylipin levels during aspirin and eicosapentaenoic acid treatment in the seAFOod polyp prevention trial

BACKGROUND

Aspirin and eicosapentaenoic acid (EPA) have colorectal polyp prevention activity, alone and in combination. This study measured levels of plasma and rectal mucosal oxylipins in participants of the seAFOod 2 × 2 factorial, randomised, placebo-controlled trial, who received aspirin 300 mg daily and EPA 2000 mg free fatty acid, alone and in combination, for 12 months.

METHODS

Resolvin (Rv) E1, 15-epi-lipoxin (LX) A₄ and respective precursors 18-HEPE and 15-HETE (with chiral separation) were measured by ultra-high performance liquid chromatography-tandem mass spectrometry in plasma taken at baseline, 6 months and 12 months, as well as rectal mucosa obtained at trial exit colonoscopy at 12 months, in 401 trial participants.

RESULTS

Despite detection of S- and R- enantiomers of 18-HEPE and 15-HETE in ng/ml concentrations, RvE1 or 15‑epi-LXA₄ were not detected above a limit of detection of 20 pg/ml in plasma or rectal mucosa, even in individuals randomised to both aspirin and EPA. We have confirmed in a large clinical trial cohort that prolonged (12 months) treatment with EPA is associated with increased plasma 18-HEPE concentrations (median [inter-quartile range] total 18-HEPE 0.51 [0.21-1.95] ng/ml at baseline versus 0.95 [0.46-4.06] ng/ml at 6 months [P<0.0001] in those randomised to EPA alone), which correlate strongly with respective rectal mucosal 18-HEPE levels (r = 0.82; P<0.001), but which do not predict polyp prevention efficacy by EPA or aspirin.

CONCLUSION

Analysis of seAFOod trial plasma and rectal mucosal samples has not provided evidence of synthesis of the EPA-derived specialised pro-resolving mediator RvE1 or aspirin-trigged lipoxin 15‑epi-LXA₄. We cannot rule out degradation of individual oxylipins during sample collection and storage but readily measurable precursor oxylipins argues against widespread degradation.

Non-Alcoholic Fatty Liver Disease and Vitamin D in the UK Biobank: A Two-Sample Bidirectional Mendelian Randomisation Study

Evidence for a role for vitamin D in non-alcoholic fatty liver disease (NAFLD) pathogenesis is conflicting. As Mendelian randomisation (MR) avoids many limitations of conventional observational studies, this two-sample bidirectional MR analysis was conducted to determine the following: (i) whether genetically predicted 25-hydroxyvitamin D [25(OH)D] levels are a risk factor for NAFLD, and (ii) whether genetic risk for NAFLD influences 25(OH)D levels. Single-nucleotide polymorphisms (SNPs) associated with serum 25(OH)D levels were obtained from the European ancestry-derived SUNLIGHT consortium. SNPs associated with NAFLD or NASH (p-value < 1 × 10−5) were extracted from previous studies and supplemented by genome-wide association studies (GWASs) performed in the UK Biobank. These GWASs were done both without (primary analysis) and with (sensitivity analysis) the population-level exclusion of other liver diseases (e.g., alcoholic liver diseases, toxic liver diseases, viral hepatitis, etc.). Subsequently, MR analyses were performed to obtain effect estimates using inverse variance weighted (IVW) random effect models. Cochran’s Q statistic, MR-Egger regression intercept, MR pleiotropy residual sum and outlier (MR-PRESSO) analyses were used to assess pleiotropy. No causal association of genetically predicted serum 25(OH)D (per standard deviation increase) with risk of NAFLD was identified in either the primary analysis: n = 2757 cases, n = 460,161 controls, odds ratio (95% confidence interval): 0.95 (0.76, −1.18), p = 0.614; or the sensitivity analysis. Reciprocally, no causal association was identified between the genetic risk of NAFLD and serum 25(OH)D levels, OR = 1.00 (0.99, 1.02, p = 0.665). In conclusion, this MR analysis found no evidence of an association between serum 25(OH)D levels and NAFLD in a large European cohort.

Unique Metabolic Profiles Associate with Gestational Diabetes and Ethnicity in Low- and High-Risk Women Living in the UK

BACKGROUND

Gestational diabetes mellitus (GDM) is the most common global pregnancy complication; however, prevalence varies substantially between ethnicities, with South Asians (SAs) experiencing up to 3 times the risk of the disease compared with white Europeans (WEs). Factors driving this discrepancy are unclear, although the metabolome is of great interest as GDM is known to be characterized by metabolic dysregulation.

OBJECTIVES

The primary aim was to characterize and compare the metabolic profiles of GDM in SA and WE women (at <28 wk of gestation) from the Born in Bradford (BIB) prospective birth cohort in the United Kingdom.

METHODS

In total, 146 fasting serum metabolites, from 2,668 pregnant WE and 2,671 pregnant SA women (average BMI 26.2 kg/m2, average age 27.3 y) were analyzed using partial least squares discriminatory analyses to characterize GDM status. Linear associations between metabolite values and post-oral glucose tolerance test measures of dysglycemia (fasting glucose and 2 h postglucose) were also examined.

RESULTS

Seven metabolites associated with GDM status in both ethnicities (variable importance in projection ≥1), whereas 6 additional metabolites associated with GDM only in WE women. Unique metabolic profiles were observed in healthy-weight women who later developed GDM, with distinct metabolite patterns identified by ethnicity and BMI status. Of the metabolite values analyzed in relation to dysglycemia, lactate, histidine, apolipoprotein A1, HDL cholesterol, and HDL2 cholesterol associated with decreased glucose concentration, whereas DHA and the diameter of very low-density lipoprotein particles (nm) associated with increased glucose concertation in WE women, and in SAs, albumin alone associated with decreased glucose concentration.

CONCLUSIONS

This study shows that the metabolic risk profile for GDM differs between WE and SA women enrolled in BiB in the United Kingdom. This suggests that etiology of the disease differs between ethnic groups and that ethnic-appropriate prevention strategies may be beneficial.

Ethnic-specific associations between dietary consumption and gestational diabetes mellitus incidence: A meta-analysis

Globally, one in seven pregnant women are diagnosed with gestational diabetes mellitus (GDM), conferring short- and long-term health risks to both mother and child. While dietary prevention strategies are common in clinical practice, their effectiveness in different ethnicities is uncertain. To better inform prevention strategies, here the effects of unhealthy and healthy diets on GDM risk within distinct ethnic or cultural populations and geographic regions were evaluated and summarised. Pubmed, Scopus, Cochrane and OVID were systematically searched to identify randomised controlled trials (RCTs) and observational studies that investigated diet and GDM. A grouped analysis of common 'healthy' and 'unhealthy' diets was performed first, before analysing individual dietary patterns (e.g., prudent, Mediterranean). Random effect models and dose response analyses were performed where possible. PROSPERO (CRD42019140873). Thirty-eight publications provided information on 5 population groups: white European (WE), Asian, Iranian, Mediterranean and Australian. No associations were identified between healthy diets and GDM incidence in RCTs in any population. However, when synthesizing observational studies, healthy diets reduced odds of GDM by 23% (95% CI: 0.70-0.89, p<0.001, I2 = 75%), while unhealthy diets increased odds of GDM by 61% (95% CI: 1.41-1.81, p<0.0001, I2 = 0%) in WE women. No evidence of consistent effects in other populations were observed, even when adequately powered. Diet consistently associated with GDM risk in WEs but not in other populations. Heterogenous use and reporting of ethnically and culturally appropriate diets and dietary assessment tools, particularly in RCTs, raises uncertainty regarding the lack of association found in non-WE populations. Future studies require the use of culturally appropriate tools to confidently evaluate dietary and metabolic mediators of GDM and inform culturally-specific dietary prevention strategies.

Distinct Serum Metabolic Profiles in Early Pregnancy Characterise Gestational Diabetes Mellitus Incidence in High-Risk Women

Objectives

This study aimed to investigate and characterise the metabolic profiles of gestational diabetes mellitus (GDM) in white European (WE) and British Pakistani (BP) women with and without GDM.

Methods

146 serum metabolites quantified by nuclear magnetic resonance, from 2668 WEs and 2671 BP pregnant women ≤28 weeks’ gestation from the Born in Bradford cohort were analysed. Partial least squares discriminatory analyses (PLSDA) and sparse PLSDA (sPLSDA) were used to investigate the ethnic-specific metabolite signatures of future incidence of GDM. Metabolite features driven by pre-pregnancy weight status and known GDM risk factors (age, parity, multiple pregnancies and smoking status) were also explored.

Results

Models explained 60% of variance between future GDM cases/non-cases in WE mothers but only 35% in BPs, after adjusting for BMI, age, parity, smoking, and non-singleton pregnancies. Across both ethnic groups, 8 metabolites associated with future GDM status. When ethnic groups were investigated independently, 7 additional metabolites associated with future GDM in WEs were identified, while no additional associations were observed in BPs. Further stratification by BMI (healthy vs overweight/obese) uncovered a metabolic profile (characterised by fatty acids and glycolytic metabolites) unique to normal-weight BP women who later developed GDM. No difference was observed between the metabolic profiles of overweight/obese women, irrespective of ethnicity.

Conclusions

In early pregnancy, the metabolomes of future GDM cases and non-cases are distinct and differ by ethnicity. While the metabolic profiles of overweight women are largely similar in WE and BPs, a unique metabolic profile was observed in healthy weight BP women who went on to develop GDM and offers insight into the early metabolomic perturbations that precede GDM development in this high-risk (but healthy) population. Further exploration regarding the interaction between genetics and lifestyle on modifying metabolic profiles associated with GDM risk will help inform ethnically appropriate nutrition strategies.

Funding Sources

HF is supported by a doctoral scholarship from the University of Leeds.

Age-related reference curves of volumetric bone density, structure, and biomechanical parameters adjusted for weight and height in a population of healthy women: an HR-pQCT study

In a cross-sectional cohort of 450 healthy women aged 20 to 85 years, data on the density, structure, and strength of the distal radius and tibia were obtained using high-resolution peripheral quantitative computed tomography (HR-pQCT) and were adjusted for age, weight, and height. Age-dependent patterns of change differed between the sites and between the trabecular and cortical compartments. In postmenopausal women, the trabecular bone remained relatively stable at the distal tibia, but the cortical compartment changed significantly. Cortical porosity exhibited a very weak correlation with stiffness.

INTRODUCTION

The aim of this study is to provide information on age-related, weight-related, and height-related changes in the volumetric bone mineral density (vBMD), structure, and biomechanical parameters of the cortical and trabecular compartments in a healthy female population using HR-pQCT.

METHODS

For a cross-sectional Brazilian cohort of 450 women aged 20 to 85 years, age-related reference curves of the vBMD, structure, and biomechanical parameters of the distal radius (DR) and distal tibia (DT) were constructed and adjusted for weight and height, and comparisons between premenopausal and postmenopausal women were performed.

RESULTS

Reference curves were obtained for all parameters. At the DR, age-related changes varied from -8.68% (cortical thickness [Ct.Th]) to 26.7% (trabecular separation [Tb.Sp]). At the DT, the changes varied from -12.4% (Ct.Th) to 26.3% (Tb.Sp). Cortical porosity (Ct.Po) exhibited the largest percent changes: 342.2% at the DR and 381.5% at the DT. In premenopausal women, Ct.Th remained constant; in postmenopausal women, structural trabecular parameters (trabecular number (Tb.N), trabecular thickness (Tb.Th), Tb.Sp) did not change, whereas cortical parameters and stiffness were significantly altered. Cortical vBMD showed the greatest absolute decrease at both sites, and the slopes were highly negative after menopause. Pearson correlations between stiffness (S) and HR-pCT parameters revealed a significant correlation between the densities and structures of the trabecular and cortical compartments. A weak correlation was observed between S and Ct.Po (DR r = -0.162, DT r = -0.273; p < 0.05).

CONCLUSIONS

These data provide reference curves from healthy women and demonstrate that density and structural and biomechanical parameters differ between the radius and tibia and between the trabecular and cortical compartments. In postmenopausal women, the trabecular bone remained relatively stable at the tibia site, whereas the cortical compartment changed significantly.

Immunoglobulin treatment for respiratory syncytial virus infection

BACKGROUND

Respiratory syncytial virus (RSV) bronchiolitis and pneumonia hospitalize hundreds of thousands of infants every year. Treatment is largely supportive therapy, (for example, oxygen, fluids and occasionally mechanical ventilation). Ribavirin, an antiviral agent, is licensed for severe RSV infection, although systematic reviews find it of no benefit. Passive protection against RSV can be achieved through monthly intramuscular injection of the humanized monoclonal anti-RSV antibody palivizumab (Synagis), and yields a 55% reduction in RSV hospitalisation in susceptible infants. This review assesses immunoglobulin treatment of RSV infection rather than its role as a prophylactic measure.

OBJECTIVES

To assess the efficacy of adding human or humanized immunoglobulin therapy to supportive therapy in infants hospitalized with laboratory-determined RSV infection.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1, 2006), MEDLINE (1966 to Week 4, January 2006) and EMBASE (1980 to September 2005). We also ran searches of reference lists of relevant trials and review articles and searches of personal files. We did not impose any language restrictions.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) that compared immunoglobulin treatment with a placebo control in children hospitalized for RSV infection with bronchiolitis or pneumonia or other lower respiratory tract infection (LRTI) with laboratory-documented RSV infection. The primary outcomes of interest were mortality, length of hospitalisation, length of ventilation and oxygen dependence. Secondary outcome measures were pulmonary function and re-hospitalisations for recurrent breathing difficulties in subsequent years. Any adverse effects of the treatments were also noted, for example, hypersensitivity reactions.

DATA COLLECTION AND ANALYSIS

Data were extracted but cross-comparison was not possible due to the shortage of studies and lack comparative measurements.

MAIN RESULTS

Four papers fitted the search criteria. None demonstrated statistically significant benefit of intravenous immunoglobulin (IVIG) treatment added to supportive care compared with supportive care alone. The evidence does not support a role for RSVIG in such a setting, with the doses used in the studies.

AUTHORS' CONCLUSIONS

The evidence on the role of respiratory syncytial virus immunoglobulin (RSVIG) in treating RSV severe infections is limited. Future research might consider using stronger titres of neutralising antibodies; and further analyse severely ill children (who might respond differentially compared to those less ill, but yet hospitalised).

IPSE/alpha-1: a major immunogenic component secreted from Schistosoma mansoni eggs

During infection with Schistosoma mansoni the egg stage of this parasite modulates the initial T helper (Th1) response into a Th2 response. This suggests that schistosome eggs contain factors responsible for that effect. We have recently described a glycoprotein (IPSE) from S. mansoni eggs that has a potent IL-4-inducing effect on human basophils. Here we demonstrate that IPSE is identical to a previously described molecule, the S. mansoni egg antigen alpha-1. We furthermore show that the expression of IPSE/alpha-1 at the level of both mRNA and protein is restricted to the egg stage. IPSE/alpha-1 is produced in and released from the subshell area of the egg and comes into close contact with inflammatory cells recruited to the vicinity of the egg surface. In line with this IPSE/alpha-1 is one of three major S. mansoni egg glycoproteins that induce pronounced antibody responses. Its IL-4-inducing capacity, moreover, suggests that IPSE/alpha-1 plays a role in initiating the Th2 response induced by patent S. mansoni infections.

Comparison of two sampling techniques for the detection of Malassezia pachydermatis on the skin of dogs with chronic dermatitis

Adhesive tape strip and dry swab sampling techniques were compared for the detection of Malassezia pachydermatis on the skin of dogs with chronic dermatitis. One hundred and four dogs were sampled by each of the techniques. Two methods, a culture method and a stain method, were used to assess the sampling techniques. By the adhesive tape strip sampling technique, M. pachydermatis was detected on 83 (80%) dogs using the culture method and on 45 (43%) dogs using the stain method. By the dry swab sampling technique, M. pachydermatis was detected on 55 (53%) dogs using the culture method and on 33 (32%) dogs using the stain method. The study showed that the adhesive tape strip sampling technique, using the culture method, detected Malassezia on the skin of significantly more dogs (P<0.001) than the same technique using the stain method and also significantly more than the dry swab sampling technique, using either the culture or stain methods. It was also shown that an adhesive tape sample could be used to transfer cells to a slide for staining and microscopy prior to being used for culturing Malassezia.

Adjudicating ventilator-associated pneumonia in a randomized trial of critically ill patients

PURPOSE

The purpose of this study was to evaluate an adjudication strategy for diagnosing ventilator-associated pneumonia (VAP) in a randomized trial.

MATERIALS AND METHODS

In a double-blind trial of sucralfate versus ranitidine, one of four pairs of adjudicators examined each case of clinically suspected VAP. Nurse and physician notes and all relevant laboratory data were allocated to each adjudication pair in groups of five patients. Each reader in the pair decided whether the patient had VAP; differences were resolved by consensus discussion.

RESULTS

The overall unadjusted study odds ratio for VAP was 0.82 (P = .21) representing a trend toward less pneumonia with sucralfate compared with ranitidine. The odds ratio adjusted for adjudication pair was 0.85 (P = .27). The proportion of charts adjudicated as VAP positive among pairs ranged from 50% to 92%; crude agreement between readers in each pair varied from 50% to 82%. When adjudicators disagreed, the final consensus was split evenly between the two adjudicators' initial opinions in two pairs; in the other two pairs, the final decision reflected one dominant initial opinion. Personnel time to adjudicate all patients with a suspicion of VAP was 74 days.

CONCLUSIONS

Though adjudication of outcomes such as VAP is time-consuming, consistent decision-making requires strict criteria, training, and calibration. Patients should be assigned to adjudication teams through random allocation.

A comparison of sucralfate and ranitidine for the prevention of upper gastrointestinal bleeding in patients requiring mechanical ventilation. Canadian Critical Care Trials Group

BACKGROUND

Critically ill patients who require mechanical ventilation are at increased risk for gastrointestinal bleeding from stress ulcers. There are conflicting data on the effect of histamine H2-receptor antagonists and the cytoprotective agent sucralfate on rates of gastrointestinal bleeding, ventilator-associated pneumonia, and mortality.

METHODS

In a multicenter, randomized, blinded, placebo-controlled trial, we compared sucralfate with the H2-receptor antagonist ranitidine for the prevention of upper gastrointestinal bleeding in 1200 patients who required mechanical ventilation. Patients received either nasogastric sucralfate suspension (1 g every six hours) and an intravenous placebo or intravenous ranitidine (50 mg every eight hours) and a nasogastric placebo.

RESULTS

The patients in the two groups had similar base-line characteristics. Clinically important gastrointestinal bleeding developed in 10 of 596 (1.7 percent) of the patients receiving ranitidine, as compared with 23 of 604 (3.8 percent) of those receiving sucralfate (relative risk, 0.44; 95 percent confidence interval, 0.21 to 0.92; P=0.02). In the ranitidine group, 114 of 596 patients (19.1 percent) had ventilator-associated pneumonia, as compared with 98 of 604 (16.2 percent) in the sucralfate group (relative risk, 1.18; 95 percent confidence interval, 0.92 to 1.51; P=0.19). There was no significant difference between the groups in mortality in the intensive care unit (ICU) (23.5 percent in the ranitidine group and 22.9 percent in the sucralfate group) or the duration of the stay in the ICU (median, nine days in both groups).

CONCLUSIONS

Among critically ill patients requiring mechanical ventilation, those receiving ranitidine had a significantly lower rate of clinically important gastrointestinal bleeding than those treated with sucralfate. There were no significant differences in the rates of ventilator-associated pneumonia, the duration of the stay in the ICU, or mortality.

Effect of magnesium on the intestinal absorption of calcium in man

OBJECTIVE

In view of the widespread use of magnesium (Mg) as a nutritional supplement, we investigated whether Mg would affect the absorption of calcium (Ca) as the intestinal absorption sites for Mg and Ca differ.

METHODS

The intestinal absorption of Ca, using 47CaCl2 as the tracer, and metabolic balances of Ca, phosphorus (P) and Mg were determined in five adult males under strictly controlled dietary conditions in control studies and during Mg supplementation. Mg was given as magnesium oxide (MgO) in 10 studies during two Ca intakes: five studies during a low Ca intake of 241 mg/day and five studies during a normal Ca intake of 812 mg/day. Dietary Mg intake ranged from 241 to 264 mg/day in control studies. During Mg supplementation, the total Mg intake ranged from 789 to 826 mg/day.

RESULTS

There was no change of the intestinal Ca absorption during Mg supplementation during the two Ca intakes. The only change was the higher 1-hour 47Ca plasma level in the 47Ca absorption studies during the high Mg intake. Urinary Ca increased during Mg supplementation only during the low Ca intake, the Ca balance became more negative but this difference was not significant. There was also no change in Ca excretion or Ca balance during the high Mg intake at the normal Ca intake of 800 mg/day. P balance studies showed a slight decrease in urinary P and an increase in fecal P, but the P balances did not change. Mg balances were negative in control studies during the two Ca intakes. Supplemental Mg increased both urinary and fecal Mg excretion and the Mg balance became positive, but these differences were not significant.

CONCLUSION

The increased Mg intake of 826 mg did not affect intestinal Ca absorption determined with tracer doses of 47Ca during Ca intakes of 241 and 812 mg/day.

Prevalence of hypertension among diabetic patients and its relation to vascular risk. Diabetes Hypertension Study Group

In order to determine the factors related to the occurrence of hypertension in diabetic patients, blood pressure distributions were determined, using standardised methods, in a sample of 5,842 patients attending ten diabetic clinics in the London area. After allowing for the influence of age and obesity, BPs tended to be higher in patients with non-insulin-dependent diabetes compared with those with insulin-dependent diabetes, and were in general higher in males compared with females. Average BPs were lower in South Indian patients when contrasted with Caucasians and Afro-Caribbeans. The frequency of WHO-defined hypertension was highest in the non-insulin-dependent patients older than 55 years, being 43% for males and 52% for females. A substantial proportion of subjects already taking anti-hypertensive treatment had BPs above 160/95 mmHg. Centile distributions of BP in this population have been used to assess the implications of treatment strategies in diabetic patients.

An observation of the dental department and the treatment needs of patients presenting at Dohnavur Hospital, southern India

A hope and a prayer, and a healthy measure of innovative inspiration, makes Dohnavur a surprisingly archaic, but reassuringly effective hospital, despite the appalling shortage of funds and equipment. Rebekah Anderson and Helen Fuller spent the month of their student elective in southern India and here reveal some of the dental anachronisms they encountered.

X-linked megalocornea: close linkage to DXS87 and DXS94

In a family in which X-linked megalocornea is segregating, the disease locus was found to be closely linked to DXS87 (zeta max = 3.91, theta max = 0.00) and DXS94 (zeta max = 3.34, theta max = 0.00) in Xq21.3-q22.

The current status and future directions of impedance cardiography in ICU

Impedance cardiography has not achieved popularity in the Intensive Care Unit (ICU) to date probably because of the limitations in technique and interpretation associated with the altered physiology of critically ill patients, and also because of interference from other machinery in the ICU. The current climate of questioning the existing technology for bedside cardiovascular assessment however spurs the need to evaluate impedance cardiography as a noninvasive alternative. Validation in noncritically ill patients is good when compared to other technologies (e.g., thermodilution, Fick, dye dilution (r greater than 0.9)). Reliability is good with a coefficient of variation in an ICU population of 8.9%, (compared to 18.6% for thermodilution). It has also shown promise in detecting the clinically significant changes of central intravascular volume. Impedance cardiography appears to be useful for measurement of stroke volume (SV) and ejection fraction (EF). From these, left ventricular end-diastolic volume (VED) can be calculated, probably a more reliable estimate of left ventricular filling than pulmonary capillary wedge pressure (PW), measured by pulmonary artery (PA) catheter. In addition, VES can be calculated and with the knowledge of left ventricular end-systolic pressure (PES) (from invasive arterial monitoring), an end-systolic pressure-volume (ES-PV) relationship can be derived. This is thought to be a measure of contractility that is independent of preload and afterload. The ultimate test in the ICU for impedance cardiography is whether clinical outcome of critically ill patients is altered by the use of this technology. Such outcome testing is essential before the true value of impedance cardiography in the management of critically ill patients can be determined.

Acute non-dilating obstructive renal failure in a patient with AIDS

A 30-year-old male who presented with acute renal failure was found to have acquired immunodeficiency syndrome (AIDS). Although sonography and computerized tomography did not show urinary tract dilatation, obstructive renal failure was demonstrated by retrograde pyelography. Relief of obstruction(s) due to encasement of the renal pelves and ureters with histiocytic lymphoma led to immediate return of normal renal function. Although the etiology of renal failure in this patient is highly unusual, the high incidence of lymphoma in patients with AIDS should make tumor-related renal disease a consideration in all such patients with renal dysfunction.