Small bowel obstruction caused by a fibrotic bow-string appendix: a consequence of non-operative management of acute appendicitis

A 73-year-old woman presented with small bowel obstruction that failed to settle with conservative management. Over the previous 2 years she had presented twice with computed tomography scan-proven acute appendicitis with localised perforation of the appendix tip. In view of medical comorbidities, she was treated non-operatively with clinical and radiological resolution on each occasion, but on the third presentation laparoscopy was undertaken for non-resolving small bowel obstruction and the non-inflamed appendix itself was identified as a fibrous band causing compression of the distal ileum and complete small bowel obstruction. Following division and appendicectomy, the patient made an uneventful recovery. This case illustrates the potential consequence of repeated appendiceal inflammation and non-operative management and may be seen increasingly as this approach is widely adopted during the COVID-19 pandemic.

982 Embolisation of Iatrogenic Lumbar Artery Bleed Causing Psoas Haematoma Following Elective Lumbar Puncture

The case of a 59-year-old female patient presenting as a surgical emergency with abdominal pain and a positive Obraztsova's sign. Seven days prior to the presentation, she had attended her General Practice (GP) complaining of sudden onset severe occipital headache associated with photophobia, vertigo, and paraesthesia. Due to a family history of cerebral aneurysms, her GP urgently transferred her to an emergency department, where she was subsequently admitted under the acute medical team. A lumbar puncture (LP) had been performed to exclude a subarachnoid haemorrhage. The patient was investigated with a Computerised Tomography abdomen and pelvis with contrast and was subsequently found to have an acute lumbar arterial bleed causing haemodynamic instability and a psoas haematoma. An emergency lumbar artery embolisation procedure was performed by the interventional radiology department in order to stabilise the bleed. The patient made a full recovery prior to discharge. This rare case exemplifies the value of obtaining adequate history in arriving at a diagnosis. In the appropriate clinical context, a contrast-enhanced CT scan of the abdomen and pelvis should be obtained to exclude this treatable condition. Also, measures to minimize the risk of complications and make lumbar puncture safer should be incorporated into guidelines, including methods to ensure that the correct position of L3/L4 or L4/L5 is found prior to performing the procedure, use of atraumatic spinal needles and performing the procedure under ultrasound guidance.

Long-term outcomes of real world 'watch and wait' data for rectal cancer after neoadjuvant chemoradiotherapy

AIM

A 'watch and wait' (W&W) strategy after neoadjuvant long-course chemoradiotherapy (NACRT) remains controversial. Whilst encouraging short-term data exist, the strategy will be judged on long-term data. We present long-term, real-world UK data from a single National Health Service trust.

METHODS

An analysis was performed of a prospectively maintained W&W database over 9 years between 2010 and 2018. Outcome measures include incidence and time to regrowth and overall and disease-free survival.

RESULTS

We diagnosed 563 rectal cancers in 9 years. In all, 283 patients underwent rectal resection (50.3%). NACRT was used in 155 patients for margin-threatened tumours on staging MRI. Forty-nine patients (31.6%) experienced either a 'near complete' or a complete clinical response (cCR) at their 10 weeks post-NACRT assessment (MRI and endoscopy). The median age was 69 years (range 44-83), and the male to female ratio was 32:17. The median follow-up was 38 months (range 12-96). The median tumour distance from the anal verge was 7 cm (1-15 cm). Twenty-two patients had a cCR on initial assessment and 27 patients had a 'near' cCR. Of those 27 who experienced a 'near' cCR, 17 (63%) progressed to cCR on repeat assessment and 10 (37%) did not. Of these 10 patients, seven underwent standard surgical resection and three were unfit for surgery. R0 for the seven with delayed resection was 100%. Of 39 patients (22 cCR and 17 'near' cCR who progressed to cCR) (25.2% of those receiving NACRT), six patients experienced local regrowth (15.4%). The median time to local regrowth was 29 months (15-60 months). One of these six patients underwent salvage abdominoperineal resection, one was advised to have contact radiotherapy and four opted against surgery and also had contact radiotherapy. The overall survival was 100% at 2 years and 90% at 5 years. Disease-free survival was 90.47% at 2 years and 74.8% at 5 years.

CONCLUSION

A W&W treatment strategy was employed safely in this patient cohort with acceptable rates of local regrowth and survival.

Biochemical and anaplerotic applications of in vitro models of propionic acidemia and methylmalonic acidemia using patient-derived primary hepatocytes

Propionic acidemia (PA) and methylmalonic acidemia (MMA) are autosomal recessive disorders of propionyl-CoA (P-CoA) catabolism, which are caused by a deficiency in the enzyme propionyl-CoA carboxylase or the enzyme methylmalonyl-CoA (MM-CoA) mutase, respectively. The functional consequence of PA or MMA is the inability to catabolize P-CoA to MM-CoA or MM-CoA to succinyl-CoA, resulting in the accumulation of P-CoA and other metabolic intermediates, such as propionylcarnitine (C3), 3-hydroxypropionic acid, methylcitric acid (MCA), and methylmalonic acid (only in MMA). P-CoA and its metabolic intermediates, at high concentrations found in PA and MMA, inhibit enzymes in the first steps of the urea cycle as well as enzymes in the tricarboxylic acid (TCA) cycle, causing a reduction in mitochondrial energy production. We previously showed that metabolic defects of PA could be recapitulated using PA patient-derived primary hepatocytes in a novel organotypic system. Here, we sought to investigate whether treatment of normal human primary hepatocytes with propionate would recapitulate some of the biochemical features of PA and MMA in the same platform. We found that high levels of propionate resulted in high levels of intracellular P-CoA in normal hepatocytes. Analysis of TCA cycle intermediates by GC-MS/MS indicated that propionate may inhibit enzymes of the TCA cycle as shown in PA, but is also incorporated in the TCA cycle, which does not occur in PA. To better recapitulate the disease phenotype, we obtained hepatocytes derived from livers of PA and MMA patients. We characterized the PA and MMA donors by measuring key proximal biomarkers, including P-CoA, MM-CoA, as well as clinical biomarkers propionylcarnitine-to-acetylcarnitine ratios (C3/C2), MCA, and methylmalonic acid. Additionally, we used isotopically-labeled amino acids to investigate the contribution of relevant amino acids to production of P-CoA in models of metabolic stability or acute metabolic crisis. As observed clinically, we demonstrated that the isoleucine and valine catabolism pathways are the greatest sources of P-CoA in PA and MMA donor cells and that each donor showed differential sensitivity to isoleucine and valine. We also studied the effects of disodium citrate, an anaplerotic therapy, which resulted in a significant increase in the absolute concentration of TCA cycle intermediates, which is in agreement with the benefit observed clinically. Our human cell-based PA and MMA disease models can inform preclinical drug discovery and development where mouse models of these diseases are inaccurate, particularly in well-described species differences in branched-chain amino acid catabolism.

Identifying risk factors for perinatal death at Tororo District Hospital, Uganda: a case-control study

Background

Sub-Saharan Africa faces a disproportionate burden of perinatal deaths globally. However, data to inform targeted interventions on an institutional level is lacking, especially in rural settings. The objective of this study is to identify risk factors for perinatal death at a resource-limited hospital in Uganda.

Methods

This is a retrospective case-control study at a district hospital in eastern Uganda using birth registry data. Cases were admissions with stillbirths at or beyond 24 weeks or neonatal deaths within 28 days of birth. Controls were admissions that resulted in deliveries immediately preceding and following each case. We compared demographic and obstetric factors between cases and controls to identify risk factors for perinatal death. Subgroup analysis of type of perinatal death was also performed. Chi square, Fisher’s exact, t-test, and Wilcoxon-Mann-Whitney rank sum tests were utilized for bivariate analysis, and multiple logistic regression for multivariate analysis.

Results

From January 2014 to December 2014, there were 185 cases of perinatal death, of which 36% (n = 69) were macerated stillbirths, 40% (n = 76) were fresh stillbirths, and 25% (n = 47) were neonatal deaths. The rate of perinatal death among all deliveries at the institution was 35.5 per 1000 deliveries. Factors associated with increased odds perinatal death included: prematurity (adjusted odds ratio (aOR) 19.7, 95% confidence interval (CI) 7.2–49.2), breech presentation (aOR 7.0, CI 1.4–35.5), multiple gestation (aOR 4.0, CI 1.1–13.9), cesarean delivery (aOR 3.8, CI 2.3–6.4) and low birth weight (aOR 2.5, CI 1.1–5.3). Analysis by subtype of perinatal death revealed distinct associations with the aforementioned risk factors, in particular for antepartum hemorrhage, which was only associated with fresh stillbirths (aOR 6.7, CI 1.6–28.8), and low birth weight.

Conclusions

The rate of perinatal death at our rural hospital site was higher than national targets, and these deaths were associated with prematurity, low birth weight, breech presentation, multiple gestation, and cesarean delivery. This data and the approach utilized to acquire it can be leveraged to inform targeted interventions to reduce the rate of stillbirths and neonatal deaths in similar low resource settings.

Toxigenic Clostridium difficile carriage in general practice: results of a laboratory-based cohort study

OBJECTIVES

Reported rates of community-acquired Clostridium difficile infections (CDIs) have been increasing. However, the true burden of the disease in general practice is unknown in France. Our objective was to determine the incidence of toxigenic C. difficile carriage and the percentage of stool samples prescribed by general practitioners (GPs) which contained free C. difficile toxins.

METHODS

During an 11-month period, all stool samples submitted for any enteric pathogen detection to 15 different private laboratories in Paris and the surrounding areas were tested for C. difficile, irrespective of the GPs' request. A clinical questionnaire was completed for each patient. Stool samples were screened using a rapid simultaneous glutamate dehydrogenase and toxins A/B detection test: any positive result (glutamate dehydrogenase or toxin) was further confirmed by the stool cytotoxicity assay (CTA) on MRC-5 cells and by toxigenic culture (TC) at a central laboratory. The C. difficile isolates were characterized by PCR ribotyping.

RESULTS

A total of 2541 patients (1295 female, 1246 male) were included. The incidences of patients with a positive toxigenic culture and a positive CTA were 3.27% (95% CI 2.61%-4.03%) and 1.81% (95% CI 1.33%-2.41%), respectively. GPs requested C. difficile testing in only 12.93% of the stool samples, detecting 52.30% of all TC-positive patients. The 83 toxigenic C. difficile strains belonged to 36 different PCR ribotypes.

CONCLUSIONS

Toxigenic C. difficile carriage is frequent in general practice but remains under-recognized. It may affect young patients without previous antimicrobial therapy or hospitalization.

Storage Levels of Ddt Metabolites in Mouse Tissues following Long Term Exposure to Technical DDT

The storage levels of DDT and its metabolites, following the long term administration of technical DDT at the dose levels of 2, 20, 50 and 250 ppm to mice, were evaluated in the fat tissue, liver, kidney, brain and reproductive organs. In addition, storage levels were evaluated in foetuses and newborns of DDT-treated mothers. Apart from op'-DDT, there was a direct relationship between the concentration of each metabolite in each organ and the dose to which the animal was exposed. The highest concentration of DDT and metabolites was found in the fat tissue followed by reproductive organs, liver and kidney together, and lastly brain. The most prevalent metabolite was pp'-DDT, except in the liver, where pp'-DDD showed the highest concentration. Pregnant females had lower concentrations of all metabolites than non-pregnant females. The concentration of residues in samples of total foetal litters was directly related to the concentration of DDT fed to the mother. There was a strong negative correlation between the concentration of pp'-DDT and that of pp'-DDD in the foetuses and the placentas of the same litter. A significant increase in whole body DDT concentration was observed shortly after birth.

Membrane lipid order of sub-synaptic T cell vesicles correlates with their dynamics and function

During an immune response, T cells survey antigen presenting cells for antigenic peptides via the formation of an interface known as an immunological synapse. Among the complex and dynamic biophysical phenomena occurring at this interface is the trafficking of sub-synaptic vesicles carrying a variety of proximal signalling molecules. Here, we show that rather than being a homogeneous population, these vesicles display a diversity of membrane lipid order profiles, as measured using the environmentally sensitive dye di-4-ANEPPDHQ and multi-spectral TIRF microscopy. Using live-cell imaging, vesicle tracking and a variety of small molecule drugs to manipulate components of the actin and tubulin cytoskeleton, we show that the membrane lipid order of these vesicles correlate with their dynamics. Furthermore, we show that the key proximal signalling molecule Linker for Activation of T cells (LAT) is enriched in specific vesicle populations as defined by their higher membrane order. These results imply that vesicle lipid order may represent a novel regulatory mechanism for the sorting and trafficking of signalling molecules at the immunological synapse, and, potentially, other cellular structures.

Community-wide Prevalence of Malaria Parasitemia in HIV-Infected and Uninfected Populations in a High-Transmission Setting in Uganda

BACKGROUND

Malaria control strategies depend on identifying individuals with parasitemia, who may be asymptomatic but retain the ability to transmit disease. Population-level survey data on parasitemia are limited and traditionally exclude adults and human immunodeficiency virus (HIV)-infected individuals.

METHODS

We performed a cross-sectional survey of residents aged 18 months to 94 years in Nankoma, Uganda. Blood specimens were collected using the dried blood spot technique from 9629 residents (87.6%), and samples from a subset of 4131 were tested for malaria parasites, using loop-mediated isothermal amplification. Population-level prevalence was estimated using a weighted proportion, and predictors of parasitemia were identified using a multivariate Poisson regression model.

RESULTS

The community prevalence of parasitemia was 83.8% (95% confidence interval [CI], 82.9%-84.6%). Parasite prevalence was highest among children aged 5-14 years (94.7%) and lowest among adults (61.9%). In analysis that controlled for age, HIV-infected individuals with an undetectable viral load had a lower risk of parasitemia, compared with HIV-uninfected individuals (adjusted relative risk, 0.16; 95% CI, .10-.27; P < .001).

CONCLUSIONS

In a rural Ugandan community, 2 years after distribution of long-lasting insecticide-treated bed nets, the prevalence of malaria parasitemia was high across all ages, peaking in school-aged children. Persons with well-controlled HIV infection had a lower risk of parasitemia, presumably reflecting access to HIV care.

Rectal mucocoele following subtotal colectomy for colitis

We present a unique case of a rectal mucocoele affecting a patient several years after his subtotal colectomy for ulcerative colitis. This was secondary to both a benign anorectal stenosis and a benign mucus secreting rectal adenoma. This case highlights the importance of surveillance in such patients.

Abstract 133: Hemodynamic Environment-dependent Effects of Human HDL and oxHDL on Vessel Wall Inflammation

High density lipoprotein (HDL) concentration is inversely correlated with cardiovascular disease and exerts atheroprotective effects on endothelial (EC) and smooth muscle cells (SMC). Oxidation of LDL (oxLDL) is a well-appreciated driver of atherosclerosis. What is less well known is that HDL can become oxidized (oxHDL) by myeloperoxidase, which may negate its beneficial effects. Further, previous mechanistic studies of HDL were performed on static culture ECs or SMCs that do not take into consideration in vivo hemodynamics; a critical regulator of vascular phenotype. Regional hemodynamics prime EC/SMCs towards either an atheroprotective phenotype or, in regions such as bifurcations, towards an atheroprone, pro-inflammatory phenotype. We assessed the role of the hemodynamic environment in modulating the differential response of vascular cells to human HDL or oxHDL from normal donors. To test this, HDL was added to EC/SMC cocultures primed by atheroprotective or atheroprone shear stresses derived from the human carotid bifurcation or an “Advanced Inflammatory” condition that combines atheroprone shear stress with additional atherogenic factors such as oxLDL and TNFα. In the presence of HDL, ECs under Advanced Inflammatory conditions reduced pro-inflammatory (NFkB Activity, IL6, COX2), and oxidative stress (SOD2), but did not have an effect in baseline atheroprotective and atheroprone conditions. Many of the anti-inflammatory responses of endothelial cells were retained when HDL was oxidized. Conversely, while HDL had minimal effect on SMC gene expression, oxHDL was found to reduced the atheroprotective phenotype by potently inducing oxidative and inflammatory cytokine genes/secreted proteins (IL1B, IL6). Overall, this study illustrates the importance of reproducing relevant in vivo environments in order to understand HDL-mediated mechanisms in vascular biology in vitro. This study supports that oxidation dysfunctionally transforms HDL from an atheroprotective to an inflammatory and intrinsically oxidative particle and might damage otherwise healthy regions of the vasculature. Thus, measurement of circulating HDL without consideration of HDL composition and oxidation may limit its predictive value for cardiovascular risk.

Abstract 73: Atrial Fibrillation-induced Changes in Left Atrial Hemodynamics Directly Impact the Thrombotic Potential of Human Primary Endothelial Cell Cultures

Thrombus formation in the left atrial appendage (LAA) of the heart is a source of stroke risk in patients with atrial fibrillation (Afib). Strategies to prevent thromboembolism from the LAA via restoration of normal rhythm or prevention of clot formation are limited by lack of adequate human surrogate systems that recapitulate the biology ex vivo. Endothelial cell phenotype and function in blood vessels and chambers of the heart are regulated in part by regional hemodynamics. Blood flow shear forces in the LAA are substantially altered during Afib. Thus, we hypothesized that Afib-induced alterations in hemodynamics directly impacts the thrombotic potential of the endothelium in the LAA. To test this, human primary aortic endothelial cell cultures were primed under hemodynamic shear forces simulating the human LAA during normal sinus rhythm for 24 hrs and continued under sinus rhythm or switched to simulate Afib for an additional 24 hrs. Compared to sustained sinus rhythm, Afib hemodynamics suppressed genes (qRTPCR) that define a healthy/quiescent endothelial cell phenotype (e.g. KLF2 and NOS3/eNOS) while inducing the pro-thrombotic gene F3 (tissue factor) and suppressing ADAMSTS13, MMP14 and TIMP2. To determine whether the observed molecular response produced a functional prothrombotic phenotype, hemodynamic primed aortic endothelial cells were exposed to dilute (~27% final concentration) human platelet-free plasma supplemented with Alexa488-labeled human fibrinogen, corn trypsin inhibitor and calcium. Cleavage of fibrinogen to fibrin and concomitant deposition on the endothelium was measured by quantitative confocal microscopy. When exposed to Afib hemodynamics, endothelial cells supported significant fibrin deposition that extended to greater depth (i.e., thicker) on the endothelium compared to sinus rhythm hemodynamics. In conclusion, we show for the first time a direct mechanistic link between changes in LAA hemodynamics associated with development of Afib and functional alterations in the thrombotic potential of the endothelium. This study produced a novel insight enabled by studying potential triggers of thrombosis in a context that more closely mimics the normal and pathological human in vivo environment.

Abstract 310: GLP-1 Cleavage Product (9-36)-NH2 Exerts Pro-survival Effects on Smooth Muscle Cells in Advanced Inflammatory Hemodynamic Conditions

Glucagon-like peptide-1(GLP-1), an incretin hormone, has been shown to have atheroprotective effects on the cardiovascular system in animal models of atherosclerosis and diabetes, and in several clinical trials. These beneficial effects are presumed to occur through active GLP-1 (7-36)-NH2/(7-37), and its receptor GLP-1R; however, within minutes GLP-1 (7-36)-NH2/(7-37) becomes cleaved and inactivated by DPP4 into its smaller metabolite, GLP-1 (9-36)-NH2(9-37). It still remains unclear how GLP-1 (7-36)-NH2/(7-37), its metabolites, and GLP-1R provide beneficial vascular effects. We sought to elucidate the role of GLP-1 on vessel wall health using a novel in vitro human surrogate system that cocultures human endothelial (EC) and smooth muscle cells (SMCs) and applies human hemodynamics from the carotid bifurcation, a site prone to developing atherosclerosis, combined with other atherogenic factors (oxidized LDL, TNFα). Though, we found GLP-1R to be highly expressed in ECs and SMCs from both healthy and advanced inflammatory vascular environments, atheroprotective effects from the addition of GLP-1 (7-36)-NH2 or (9-36)-NH2 acted primarily on SMCs. In SMCs from atherogenic hemodynamic conditions, GLP-1 (7-36)-NH2 reduced NFkB activity and increased the anti-oxidant response protein, HO-1, via GLP-1R. A novel finding was that the cleaved metabolite, GLP-1 (9-36)-NH2, elicited the same response. Though GLP-1 (9-36)-NH2 did not alter downstream inflammatory gene expression, the NFkB-dependent pathways converged on pro-survival signaling since the metabolite GLP-1 (9-36)-NH2 uniquely decreased apoptotic signaling, including cleaved Caspase-3. These same responses were not seen with cleavage-resistant forms of GLP-1 (7-36)-NH2, but were rescued by adding back the cleavage product, (9-36)-NH2_further illustrating the distinct role of GLP-1 (9-36)-NH2 in promoting cell survival. This suggests future therapeutics would benefit by combining native GLP-1 along with its cleavage product, GLP-1 (9-36)-NH2. These findings demonstrate the novel effect of native GLP-1 and its cleavage-products on vessel wall health and provide new insights into creating more effective GLP-1 therapeutics for treatment of atherosclerosis and diabetes.

Oseltamivir and inhaled zanamivir as influenza prophylaxis in Thai health workers: a randomized, double-blind, placebo-controlled safety trial over 16 weeks

OBJECTIVES

Long-term chemoprophylaxis using neuraminidase inhibitors may be needed during influenza epidemics but safety data are limited to several weeks. We sought to assess the tolerability of oseltamivir and zanamivir as primary prophylaxis over 16 weeks.

METHODS

We conducted a parallel group, double blind, 2 (active drug) :1 (placebo) randomized trial of oral oseltamivir/placebo or inhaled zanamivir/placebo over 16 weeks in healthy, Thai hospital professionals at two Bangkok hospitals. The primary endpoint was study withdrawal due to drug-related (possibly, probably, definitely) serious or adverse events (AEs) graded ≥ 2.

RESULTS

Recruited subjects numbered 129 oseltamivir/65 placebo and 131 zanamivir/65 placebo. A total of 102 grade ≥ 2 AEs were reported or detected in 69 subjects: 23/129 (17.8%) versus 15/65 (23.1%) (P=0.26), and 23/131 (17.6%) versus 8/65 (12.3%) (P=0.28). Intercurrent infections/fevers [26/102 (25.5%)], abnormal biochemistry [25/102 (24.5%)] and gastrointestinal symptoms [18/102 (17.6%)] were the most frequently reported AEs. There were no drug-related study withdrawals. Eight serious AEs were all due to intercurrent illnesses. Laboratory, lung function and ECG parameters were similar between drugs and placebos.

CONCLUSIONS

Oseltamivir and zanamivir were well tolerated in healthy hospital professionals. Both drugs can be recommended for primary influenza prophylaxis for up to 16 weeks.

Variation in human genes encoding adhesion and proinflammatory molecules are associated with severe malaria in the Vietnamese

The genetic basis for susceptibility to malaria has been studied widely in African populations but less is known of the contribution of specific genetic variants in Asian populations. We genotyped 67 single-nucleotide polymorphisms (SNPs) in 1030 severe malaria cases and 2840 controls from Vietnam. After data quality control, genotyping data of 956 cases and 2350 controls were analysed for 65 SNPs (3 gender confirmation, 62 positioned in/near 42 malarial candidate genes). A total of 14 SNPs were monomorphic and 2 (rs8078340 and rs33950507) were not in Hardy-Weinberg equilibrium in controls (P<0.01). In all, 7/46 SNPs in 6 genes (ICAM1, IL1A, IL17RC, IL13, LTA and TNF) were associated with severe malaria, with 3/7 SNPs in the TNF/LTA region. Genotype-phenotype correlations between SNPs and clinical parameters revealed that genotypes of rs708567 (IL17RC) correlate with parasitemia (P=0.028, r(2)=0.0086), with GG homozygotes having the lowest parasite burden. Additionally, rs708567 GG homozygotes had a decreased risk of severe malaria (P=0.007, OR=0.78 (95% CI; 0.65-0.93)) and death (P=0.028, OR=0.58 (95% CI; 0.37-0.93)) than those with AA and AG genotypes. In summary, variants in six genes encoding adhesion and proinflammatory molecules are associated with severe malaria in the Vietnamese. Further replicative studies in independent populations will be necessary to confirm these findings.