Management Strategies and Outcomes for Small Intestinal Neuroendocrine Tumours with Involvement of the Superior Mesenteric Vessels: A Systematic Review

Small intestinal neuroendocrine tumours (SI-NETs) are the most common small intestinal tumours. A particularly challenging subset of these tumours is those that involve the superior mesenteric artery or vein for which the role and feasibility of surgery are often questioned. This systematic review aimed to identify and evaluate the management strategies used for these complex SI-NETs. The identified studies showed positive outcomes with surgery and multimodality therapy.

Systematic Evaluation of the Immune Environment of Small Intestinal Neuroendocrine Tumors

PURPOSE

The immune tumor microenvironment and the potential therapeutic opportunities for immunotherapy in small intestinal neuroendocrine tumors (siNET) have not been fully defined.

EXPERIMENTAL DESIGN

Herein, we studied 40 patients with primary and synchronous metastatic siNETs, and matched blood and normal tissue obtained during surgery. We interrogated the immune checkpoint landscape using multi-parametric flow cytometry. In addition, matched FFPE tissue was obtained for multi-parametric IHC to determine the relative abundance and distribution of T-cell infiltrate. Tumor mutational burden (TMB) was also assessed and correlated with immune infiltration.

RESULTS

Effector tumor-infiltrating lymphocytes (TIL) had a higher expression of PD-1 in the tumor microenvironment compared with the periphery. In addition, CD8+ TILs had a significantly higher co-expression of PD-1/ICOS and PD-1/CTLA-4 (cytotoxic T lymphocyte antigen-4) and higher levels of PD-1 expression compared with normal tissue. IHC revealed that the majority of cases have ≤10% intra-tumoral T cells but a higher number of peri-tumoral T cells, demonstrating an "exclusion" phenotype. Finally, we confirmed that siNETs have a low TMB compared with other tumor types in the TCGA database but did not find a correlation between TMB and CD8/Treg ratio.

CONCLUSIONS

Taken together, these results suggest that a combination therapy approach will be required to enhance the immune response, using PD-1 as a checkpoint immunomodulator backbone in combination with other checkpoint targeting molecules (CTLA-4 or ICOS), or with drugs targeting other pathways to recruit "excluded" T cells into the tumor microenvironment to treat patients with siNETs.

COVID-19 and vertical transmission: assessing the expression of ACE2/TMPRSS2 in the human fetus and placenta to assess the risk of SARS-CoV-2 infection

BACKGROUND

Pregnant women have been identified as a potentially at-risk group concerning COVID-19 infection, but little is known regarding the susceptibility of the fetus to infection. Co-expression of ACE2 and TMPRSS2 has been identified as a prerequisite for infection, and expression across different tissues is known to vary between children and adults. However, the expression of these proteins in the fetus is unknown.

METHODS

We performed a retrospective analysis of a single cell data repository. The data were then validated at both gene and protein level by performing RT-qPCR and two-colour immunohistochemistry on a library of second-trimester human fetal tissues.

FINDINGS

TMPRSS2 is present at both gene and protein level in the predominantly epithelial fetal tissues analysed. ACE2 is present at significant levels only in the fetal intestine and kidney, and is not expressed in the fetal lung. The placenta also does not co-express the two proteins across the second trimester or at term.

INTERPRETATION

This dataset indicates that the lungs are unlikely to be a viable route of SARS-CoV2 fetal infection. The fetal kidney, despite presenting both the proteins required for the infection, is anatomically protected from the exposure to the virus. However, the gastrointestinal tract is likely to be susceptible to infection due to its high co-expression of both proteins, as well as its exposure to potentially infected amniotic fluid.

TWEETABLE ABSTRACT

This work provides detailed mechanistic insight into the relative protection & vulnerabilities of the fetus & placenta to SARS-CoV-2 infection by scRNAseq & protein expression analysis for ACE2 & TMPRSS2. The findings help to explain the low rate of vertical transmission.

Transcriptomic Profiling of In Vitro Tumor-Stromal Cell Paracrine Crosstalk Identifies Involvement of the Integrin Signaling Pathway in the Pathogenesis of Mesenteric Fibrosis in Human Small Intestinal Neuroendocrine Neoplasms

Aim

Analysis of the pathophysiology of mesenteric fibrosis (MF) in small intestinal neuroendocrine tumors (SI-NETs) in an in vitro paracrine model and in human SI-NET tissue samples.

Methods

An indirect co-culture model of SI-NET cells KRJ-I and P-STS with stromal cells HEK293 was designed to evaluate the paracrine effects on cell metabolic activity, gene expression by RT2 PCR Profilers to analyse cancer and fibrosis related genes, and RNA sequencing. The integrin signaling pathway, a specific Ingenuity enriched pathway, was further explored in a cohort of human SI-NET tissues by performing protein analysis and immunohistochemistry.

Results

RT Profiler array analysis demonstrated several genes to be significantly up- or down-regulated in a cell specific manner as a result of the paracrine effect. This was further confirmed by employing RNA sequencing revealing multiple signaling pathways involved in carcinogenesis and fibrogenesis that were significantly affected in these cell lines. A significant upregulation in the expression of various integrin pathway – related genes was identified in the mesenteric mass of fibrotic SI-NET as confirmed by RT-qPCR and immunohistochemistry. Protein analysis demonstrated downstream activation of the MAPK and mTOR pathways in some patients with fibrotic SI-NETs.

Conclusion

This study has provided the first comprehensive analysis of the crosstalk of SI-NET cells with stromal cells. A novel pathway – the integrin pathway – was identified and further validated and confirmed in a cohort of human SI-NET tissue featured by a dual role in fibrogenesis/carcinogenesis within the neoplastic fibrotic microenvironment.

Evaluation of circulating transcript analysis (NETest) in small intestinal neuroendocrine neoplasms after surgical resection

PURPOSE

Surgical resection is the only effective curative strategy for small intestinal neuroendocrine neoplasms (SINENs). Nevertheless, the evaluation of residual disease and prediction of disease recurrence/progression remains a problematic issue.

METHODS

We evaluated 13 SINENs that underwent surgical resection of the primary tumour and/or mesenteric mass. Patients were divided in three groups: (a) Group 1: SINENs that underwent resection with curative intent, (b) Group 2: SINENs treated with resection in the setting of metastatic disease, which remained stable and (c) Group 3: SINENs treated with resection in the setting of metastatic disease, with evidence of any progression at follow-up. NETest and chromogranin A were measured pre-operatively and post-operatively during a 22-month median follow-up period and compared with imaging studies. NETest score <20% was determined as normal, 20-40% low, 41-79% intermediate and ≥80% high score.

RESULTS

NETest score was raised in all (100%) SINENs pre-operatively. Surgery with curative intent resulted in NETest score reduction from 78.25 ± 15.32 to 25.25 ± 1.75 (p < 0.05). Low NETest scores post-operatively were evident in all cases without clinical evidence of residual disease (Group 1). However, the low disease activity score suggested the presence of microscopic residual disease. In three cases (75%) with stable disease (Group 2) the NETest score was low consistent with indolent disease. In the progressive disease group (Group 3), a high NETest score was present in three cases (60%) and an intermediate NETest score in the remainder (40%).

CONCLUSIONS

Blood NETest scores accurately identified SINENs and were significantly decreased by curative surgery. Monitoring NETest post-operatively may facilitate management by identifying the presence of residual/progressive disease.

Clinicopathological correlations of mesenteric fibrosis and evaluation of a novel biomarker for fibrosis detection in small bowel neuroendocrine neoplasms

PURPOSE

Mesenteric fibrosis (MF) in small intestinal neuroendocrine neoplasms (SINENs) is often associated with significant morbidity and mortality. The detection of MF is usually based on radiological criteria, but no previous studies have attempted a prospective, multidimensional assessment of mesenteric desmoplasia to determine the accuracy of radiological measurements. There is also a lack of non-invasive biomarkers for the detection of image-negative MF.

METHODS

A multidimensional assessment of MF incorporating radiological, surgical and histological parameters was performed in a prospective cohort of 34 patients with SINENs who underwent primary resection. Pre-operative blood samples were collected in 20 cases to evaluate a set of five profibrotic circulating transcripts-the "fibrosome"-that is included as an "omic" component of the NETest.

RESULTS

There was a significant correlation between radiological and surgical assessments of MF (p < 0.05). However, there were several cases of image-negative MF. The NETest-fibrosome demonstrated an accuracy of 100% for the detection of microscopic MF.

CONCLUSIONS

The detection of MF by radiological criteria has limitations. The NETest-fibrosome is a promising biomarker for fibrosis detection and further validation of these results would be needed in larger, multicentre studies.

Prophylactic biological mesh reinforcement versus standard closure of stoma site (ROCSS): a multicentre, randomised controlled trial

BACKGROUND

Closure of an abdominal stoma, a common elective operation, is associated with frequent complications; one of the commonest and impactful is incisional hernia formation. We aimed to investigate whether biological mesh (collagen tissue matrix) can safely reduce the incidence of incisional hernias at the stoma closure site.

METHODS

In this randomised controlled trial (ROCSS) done in 37 hospitals across three European countries (35 UK, one Denmark, one Netherlands), patients aged 18 years or older undergoing elective ileostomy or colostomy closure were randomly assigned using a computer-based algorithm in a 1:1 ratio to either biological mesh reinforcement or closure with sutures alone (control). Training in the novel technique was standardised across hospitals. Patients and outcome assessors were masked to treatment allocation. The primary outcome measure was occurrence of clinically detectable hernia 2 years after randomisation (intention to treat). A sample size of 790 patients was required to identify a 40% reduction (25% to 15%), with 90% power (15% drop-out rate). This study is registered with ClinicalTrials.gov, NCT02238964.

FINDINGS

Between Nov 28, 2012, and Nov 11, 2015, of 1286 screened patients, 790 were randomly assigned. 394 (50%) patients were randomly assigned to mesh closure and 396 (50%) to standard closure. In the mesh group, 373 (95%) of 394 patients successfully received mesh and in the control group, three patients received mesh. The clinically detectable hernia rate, the primary outcome, at 2 years was 12% (39 of 323) in the mesh group and 20% (64 of 327) in the control group (adjusted relative risk [RR] 0·62, 95% CI 0·43-0·90; p=0·012). In 455 patients for whom 1 year postoperative CT scans were available, there was a lower radiologically defined hernia rate in mesh versus control groups (20 [9%] of 229 vs 47 [21%] of 226, adjusted RR 0·42, 95% CI 0·26-0·69; p<0·001). There was also a reduction in symptomatic hernia (16%, 52 of 329 vs 19%, 64 of 331; adjusted relative risk 0·83, 0·60-1·16; p=0·29) and surgical reintervention (12%, 42 of 344 vs 16%, 54 of 346: adjusted relative risk 0·78, 0·54-1·13; p=0·19) at 2 years, but this result did not reach statistical significance. No significant differences were seen in wound infection rate, seroma rate, quality of life, pain scores, or serious adverse events.

INTERPRETATION

Reinforcement of the abdominal wall with a biological mesh at the time of stoma closure reduced clinically detectable incisional hernia within 24 months of surgery and with an acceptable safety profile. The results of this study support the use of biological mesh in stoma closure site reinforcement to reduce the early formation of incisional hernias.

FUNDING

National Institute for Health Research Research for Patient Benefit and Allergan.

The Impact of Improved Data Collection at the Ibadan Cancer Registry: Comparison of Two Time Periods (2009-2012 and 2013-2016)

Background and context: The Ibadan cancer registry is a population based registry that actively recruits cases of cancer occurring in eleven local government areas in Ibadan and its environs in Southwest, Nigeria. The registry covers a catchment area with a documented population of 2,549,265. Cases are abstracted from the main teaching hospital, designated private hospitals and clinics representing active practices, National Population Commission and private laboratories. We observed a decline in numbers of cases registered compared with what was projected and moved to effect corrections to this decline. In addition to reviewing our usual sources, we enlisted more sources of case recruitment. Aim: This study was done to assess the impact of additional sources of data collection on the number of cases recorded in the registry. Strategy/Tactics: The registry had improved contact with the local Ministry of Health and local governments administration, identified new facilities that treat cancer patients and new histopathologic laboratories that diagnose cancers. Program/Policy process: The registry enlisted cases from thirty (30) sources during 2009-2012 time period. In the 2013-2016 period, the registry improved the data collection sources to sixty (60) due to good advocacy, improved collaborative effort with our partners and very active case finding. Outcomes: A total of 3116 cases were recorded in the registry during the period 2009-2012. This increased to 3744 in the period 2013-2016 giving a 20% increase in the number of abstracted cases in the latter period. The ranking order of cancer in the population we serve changed from breast, cervix and prostate cancers in 2009-2012 to breast, prostate and cervix in the second time period. The ranking order in both genders did not change significantly. What was learned: Changes in health providing facilities affect the recruitment of new cancer cases into the database of cancer registries. Furthermore, cancer registries must always improve the database of sources where cases are recruited, as this is dynamic. Good advocacy, very active case finding and improved relation with the community have increased the number of cases of cancer recorded in our registry.

AUTOMATIC GENERATION OF ROOT LOCUS PLOTS FOR LINEAR TIME INVARIANT SYSTEMS

Design and analysis of control systems often become difficult due to the complexity of the system model and the design techniques involved. This paper presents the development of a Tools Box in Microsoft Excel for control engineer that uses root locus as a time domain technique for system design and analysis. The Tool Box can also serve as a computer-aided graphical analytical tool for trainers. The work was done in two phases: the first phase is the development of a programmable algorithms for root locus using the angle condition and bisection method while the second phase is the implementation of the developed algorithms. The implementation was done using Microsoft Excel (R) Visual Basic Application (VBA). Results of simulations for different systems show the potential of the Tool Box as an alternative for other software package and the ease of using it on the readily available Microsoft Excel environment.   http://dx.doi.org/10.4314/njt.v36i1.20

Prognostic Impact of Novel Molecular Subtypes of Small Intestinal Neuroendocrine Tumor

PURPOSE

Small intestinal neuroendocrine tumors (SINET) are the commonest malignancy of the small intestine; however, underlying pathogenic mechanisms remain poorly characterized. Whole-genome and -exome sequencing has demonstrated that SINETs are mutationally quiet, with the most frequent known mutation in the cyclin-dependent kinase inhibitor 1B gene (CDKN1B) occurring in only ∼8% of tumors, suggesting that alternative mechanisms may drive tumorigenesis. The aim of this study is to perform genome-wide molecular profiling of SINETs in order to identify pathogenic drivers based on molecular profiling. This study represents the largest unbiased integrated genomic, epigenomic, and transcriptomic analysis undertaken in this tumor type.

EXPERIMENTAL DESIGN

Here, we present data from integrated molecular analysis of SINETs (n = 97), including whole-exome or targeted CDKN1B sequencing (n = 29), HumanMethylation450 BeadChip (Illumina) array profiling (n = 69), methylated DNA immunoprecipitation sequencing (n = 16), copy-number variance analysis (n = 47), and Whole-Genome DASL (Illumina) expression array profiling (n = 43).

RESULTS

Based on molecular profiling, SINETs can be classified into three groups, which demonstrate significantly different progression-free survival after resection of primary tumor (not reached at 10 years vs. 56 months vs. 21 months, P = 0.04). Epimutations were found at a recurrence rate of up to 85%, and 21 epigenetically dysregulated genes were identified, including CDX1 (86%), CELSR3 (84%), FBP1 (84%), and GIPR (74%).

CONCLUSIONS

This is the first comprehensive integrated molecular analysis of SINETs. We have demonstrated that these tumors are highly epigenetically dysregulated. Furthermore, we have identified novel molecular subtypes with significant impact on progression-free survival.

Consensus best practice pathway of the UK scleroderma study group: gastrointestinal manifestations of systemic sclerosis

Systemic sclerosis is an autoimmune connective tissue disorder, which can be progressive with multisystem involvement. Guidance on the management of complications is based on a limited data set and practice amongst clinicians can vary. The UK Scleroderma study group set up several working groups to agree some consensus pathways for the management of specific complications. Approximately nine out of ten patients with systemic sclerosis will have involvement of the gastrointestinal system and in this review article we explore the management of these complications in a symptom-based approach. The algorithms are a useful tool for clinicians, which we hope, will be a point of reference and highlight the need for further research in these areas.

Efficacy of the specific endothelin a receptor antagonist zibotentan (ZD4054) in colorectal cancer: a preclinical study

Endothelin 1 (ET-1) is overexpressed in cancer, contributing to disease progression. We previously showed that ET-1 stimulated proliferative, migratory, and contractile tumorigenic effects via the ET(A) receptor. Here, for the first time, we evaluate zibotentan, a specific ET(A) receptor antagonist, in the setting of colorectal cancer, in cellular models. Pharmacologic characteristics were further determined in patient tissues. Colorectal cancer lines (n = 4) and fibroblast strains (n = 6), isolated from uninvolved areas of colorectal cancer specimens, were exposed to ET-1 and/or ET(A)/(B) receptor antagonists. Proliferation (methylene blue), migration (scratch wounds), and contraction (gel lattices) were assessed. Receptor distribution and binding characteristics (K(d), B(max)) were determined using autoradiography on tissue sections and homogenates and cytospun cells, supported by immunohistochemistry. Proliferation was inhibited by ET(A) (zibotentan > BQ123; P < 0.05), migration by ET(B) > ET(A), and contraction by combined ET(A) and ET(B) antagonism. Intense ET-1 stromal binding correlated with fibroblasts and endothelial cells. Colorectal cancer lines and fibroblasts revealed high density and affinity ET-1 binding (B(max) = 2.435 fmol/1 × 10(6) cells, K(d) = 367.7 pmol/L; B(max) = 3.03 fmol/1 × 10(6) cells, K(d) = 213.6 pmol/L). In cancer tissues, ET(A) receptor antagonists (zibotentan; BQ123) reduced ET-1 binding more effectively (IC(50): 0.1-10 μmol/L) than ET(B) receptor antagonist BQ788 (∼IC(50), 1 mmol/L). ET-1 stimulated cancer-contributory processes. Its localization to tumor stroma, with greatest binding/affinity to fibroblasts, implicates these cells in tumor progression. ET(A) receptor upregulation in cancer tissues and its role in tumorigenic processes show the receptor's importance in therapeutic targeting. Zibotentan, the most specific ET(A) receptor antagonist available, showed the greatest inhibition of ET-1 binding. With its known safety profile, we provide evidence for zibotentan's potential role as adjuvant therapy in colorectal cancer.

Limited ileo-caecal resection for localised Crohn's disease in childhood: Clinical outcome and predictors of further surgery

OBJECTIVES

To investigate the outcome of limited ileo-caecal resection in children with localised Crohn's disease (CD) and determine predictors of further surgery.

METHODS

Review of children diagnosed with CD and operated on for ileo-caecal disease from 1995 to 2005. Age at diagnosis, endoscopic disease distribution, indication for surgery, site of recurrence and date of last follow-up were recorded. Surgery required removal of only the ileo-caecal junction and caecal pole with removal of the minimum terminal ileal length.

RESULTS

Thirty seven children underwent intestinal resection. Time between primary operation and most recent follow-up was 3.8 years (range 1 month-8.8 years). Indications for surgery were obstruction/stricture (20), treatment-resistant disease (13) and abscess/perforation peritonitis (4). Follow-up was available in 32. Nine (28%) required re-laparotomy. Median time to second laparotomy was 12 months (range 4-58 months). Eighteen children required no endoscopies after surgery (median follow-up 3.4 years).

CONCLUSION

Most conservative surgery occurs about 2 years after diagnosis. About 1 in 4 children have a further laparotomy within 12 months. Over half of these require division of adhesions. Limited ileo-caecal resection for localized Crohn's disease is not associated with early peri-anastomotic recurrence. Developments in laparoscopic surgery are likely to further reduce complications from adhesions.

Comparison of general anaesthesia and spinal anaesthesia for caesarean section in Antigua and Barbuda

Regional anaesthesia has become the anaesthetic of choice for Caesarean section (CS) in developed countries, with use extended to smaller, less developed countries in the past decade. This study is a comparison of maternal and neonatal outcomes comparing general anaesthesia (GA) and the early experience with spinal anaesthesia (SA) for CS in Antigua and Barbuda. Data obtained included maternal age, gravidity, parity, indication for operation, emergent versus routine operation and type of anaesthesia used. Outcome data comprised estimated blood loss, transfusion requirement, length of stay, postoperative wound infection for mothers. Data obtained for babies included birthweight, one and five minute Apgar scores, neonatal special care unit admission or perinatal death. The sample population included 103 CS patients who underwent GA and 45 who underwent SA. There was no difference in age (mean 29.3 vs 29.4 years), gravidity (mean 3.25 vs 3.27), parity (mean 1.74 vs 1.56) or emergency vs routine CS (44.4% vs 49.5%). Mothers who underwent GA had significantly greater estimated blood loss (mean 787 vs 632 mL, p < 0. 02) and rate of transfusion (13.6% vs 2.2%, p < 0. 05). There was a trend toward longer hospital stay (mean 6.86 vs 6.42 days, p = 0. 16) but a lower rate of postoperative wound infection (8.7% vs 20%, p < 0. 10) for mothers who underwent GA. There were no maternal deaths. Babies demonstrated no difference in birthweight (mean 3238 vs 3258 g) but those born to mothers who underwent GA had significantly lower one minute (mean 6.84 vs 8.17, p < 0.0001) and five minute (mean 8.13 vs 8.91, p < 0.001) Apgar scores, with a trend toward more frequent neonatal special care unit admission (26.2% vs 17.7%, p < 0.20) and perinatal death (3.9 vs 0%, p < 0.30). GA and SA appear equally safe, but SA was associated with significantly better outcome for both mothers and babies.

Desmocollin switching in colorectal cancer

The desmocollins are members of the desmosomal cadherin family of cell-cell adhesion molecules. They are essential constituents of desmosomes, intercellular junctions that play a critical role in the maintenance of tissue integrity in epithelia and cardiac muscle. In humans, three desmocollins (Dsc1, Dsc2 and Dsc3) have been described. The desmocollins exhibit tissue-specific patterns of expression; only Dsc2 is expressed in normal colonic epithelium. We have found switching between desmocollins in sporadic colorectal adenocarcinoma with a reduction in Dsc2 protein (in 8/16 samples analysed by immunohistochemistry) being accompanied by de novo expression of Dsc1 (16/16) and Dsc3 (7/16). Similar results were obtained by western blotting of a further 16 samples. No change was found in Dsc2 mRNA, but de novo expression of Dscs 1 and 3 was accompanied by increased message levels. Loss of Dsc2 (8/19) and de novo expression of Dsc1 (11/19) and Dsc3 (6/19) was also found in colorectal adenocarcinomas on a background of colitis. The data raise the possibility that switching of desmocollins could play an important role in the development of colorectal cancer.

Choledochal cysts in African infants: a report of 3 cases and a review of the literature

Choledochal cysts are relatively rare and are an uncommon cause of cholestasis. Early diagnosis and prompt treatment can prevent complications such as cholangitis, cirrhosis and portal hypertension. This article reviews a rarely reported disease in Africans in whom only 3 cases were documented over the 18 year period in Nigeria. The 3 cases were all females with ages between less than a month and 13 months at presentation. All presented with abdominal swelling with or without jaundice or acholic stools. The use of real-time ultrasonography antenatally and postnatally aided the diagnosis in our patients. Two of the patients presented and were operated and both made full recovery confirming the importance of early surgical intervention. The third patient died, and exemplified the consequences of delayed diagnosis and treatment which occur not uncommonly in developing countries mostly because of sparse and or expensive tertiary health care facilities.

Kruppel-like factor 6 (KLF6) is a tumor-suppressor gene frequently inactivated in colorectal cancer

BACKGROUND & AIMS

Kruppel-like factor 6 (KLF6) is a ubiquitous zinc finger tumor suppressor that is often mutated in prostate cancer. Our aims were to establish the frequency of KLF6 inactivation in sporadic and inflammatory bowel disease (IBD)-associated colorectal cancers (CRC); to correlate these abnormalities with mutation and/or loss of TP53, APC, and K-RAS; and to characterize the behavior of mutant KLF6 in colon-derived cell lines.

METHODS

We analyzed DNA isolated from 50 microdissected CRC cases, including 35 sporadic and 15 IBD-associated tumors. Microsatellite analysis and direct sequencing were used to establish the incidence of microsatellite instability, KLF6 and TP53 allelic imbalance, and KLF6, K-RAS, TP53, and APC mutation. Loss of growth suppressive function of the CRC-derived KLF6 mutants was characterized by in vitro thymidine incorporation assays and Western blotting.

RESULTS

KLF6 was inactivated by loss and/or mutation in most sporadic and IBD-related CRCs. The KLF6 locus was deleted in at least 55% of tumors, and mutations were identified in 44%. Rates of KLF6 loss and mutation were similar to those of TP53 and K-RAS in the same samples. KLF6 mutations were present in tumors with either microsatellite or chromosomal instability and were more common, particularly in the IBD-related cancers, in the presence of wild-type APC. Unlike wild-type KLF6, cancer-derived KLF6 mutants neither suppressed growth nor induced p21 following transfection into cultured cells.

CONCLUSIONS

Deregulation of KLF6 by a combination of allelic imbalance and mutation may play a role in the development of CRC.

Presentation of primary mediastinal masses in Ibadan

OBJECTIVES

To determine clinical features, anatomic location and histological types of primary mediastinal masses diagnosed and treated in a black African population.

DESIGN

A retrospective study of clinical data collected from patients case notes, the cardiothoracic unit's and pathology records between June 1975 and May 1999.

SETTING

University College Hospital, Ibadan, Nigeria which hosts a major cancer center in the West African sub-region, and serves community clinics.

PATIENTS

All patients with primary mediastinal masses referred for evaluation and treatment.

MAIN OUTCOME MEASURES

Excluded metastatic, oesophageal and vascular-lesions. All patients had radiological evalulation and tissue biopsies. The anatomic subdivision of the mediastinum into anterosuperior, middle and posterior section was used.

RESULTS

One hundred and five consecutive patients were evaluated and treated. The mean age was 34.0 +/- 20.4 years. There were 75 males and 30 females. Eighty one (77.1%) were symptomatic, 24 (22.9%) were asymptomatic. Thirty seven (45.7%) of the symptomatic patients had malignant disease while 44 (54.3%) had benign disease. Forty five patients (43%) and 60 patients (57%) had malignant and benign diseases respectively. Incidence of symptoms, was 82.2% for malignant and 73.3% for benign diseases. This difference in incidences is statistically insignificant (p=0.283). Majority of asymptomatic patients (70.8%) had benign disease while 29.2% of patients with malignancy were asymptomatic. This difference in incidence was statistically significant (p=0.0039). The frequency of mediastinal masses were anterosuperior, in 67 patients (63.8%), posterior mediastinal, 24 patients (22.9%) and middle mediastinal in 14 patients (13.3%). Lymphoma 23 (21.9%), thymus glands tumours 19 (18.1%) and endocrine tumours (goiters) 18 (17.1%) were the commonest types of primary mediastinal masses treated.

CONCLUSION

Majority of our patients with mediastinal masses (whether benign or malignant) are symptomatic and the absence of symptoms is more associated with benign disease. Majority of lesions are situated in the anterosuperior mediastinum. Lymphoma is the most frequent primary mediastinal mass.

Crohn's disease and the NOD2 gene: a role for paneth cells

BACKGROUND & AIMS

The NOD2 gene, which is strongly associated with susceptibility to Crohn's disease (CD) of the terminal ileum, interacts with bacterial lipopolysaccharide (LPS), inducing cellular activation. However, the mechanisms by which NOD2 mutations cause terminal ileitis are unknown, and NOD2 is expressed most highly by peripheral blood monocytes, which are distributed ubiquitously and readily respond to LPS via cell-surface receptors. Paneth cells on the other hand, are most numerous in the terminal ileum, are critically important in enteric antibacterial defense, and respond to LPS through as yet undefined pathways. We therefore determined if these specialized intestinal epithelial cells also expressed the NOD2 gene.

METHODS

In situ hybridization, immunohistochemistry, and laser-capture microdissection were used to determine RNA and protein expression in tissue sections, and real-time reverse-transcription polymerase chain reaction (RT-PCR) was used to quantitate gene expression in intestinal epithelial cells and peripheral blood mononuclear cells.

RESULTS

NOD2 was detected readily in monocytes, but not in mature macrophages in the lamina propria or within granulomas, and levels declined as monocytes differentiated into macrophages in vitro, so that Caco-2 cells expressed more NOD2 mRNA than macrophages. NOD2 mRNA was enriched in crypts compared with villi, and in situ, Paneth cells were the most prominent cells expressing NOD2 in normal and CD-affected intestinal tissue, where they also strongly expressed tumor necrosis factor alpha (TNFalpha) RNA.

CONCLUSIONS

The NOD2 gene product is most abundant in Paneth cells in the terminal ileum, which could therefore play a critical and hitherto unrecognized role in the pathogenesis of NOD2-associated CD.

Hepatocellular carcinoma in Nigerian children

Childhood primary hepatocellular carcinoma is rare and accounts for less than 1% of all abdominal malignancies in children < or = 14 years of age. A review of the records of the Cancer Registry, Ibadan, Nigeria covering the period 1960-1995 was scrutinised and 19 cases of hepatocellular carcinoma (HCC) were registered, accounting for 0.49% of all abdominal malignancies over the period of review. The mean (SD) age at presentation was 10.4 (3.0) years and the duration of illness before presentation was short. All the children presented late with abdominal distension and hepatomegaly as the major clinical features. Weight loss was evident in 80% of cases, splenomegaly occurred in 50% and jaundice was present in a third of them. The prognosis was poor; all the cases died within 2 weeks of presentation in hospital. There was evidence to suggest an association between hepatitis B virus infection and HCC in all the liver tissue stained by Shikata-Orcein. This review shows that HCC, though uncommon, is important enough to be considered a possible cause of unexplained hepatomegaly in Nigerian children and that hepatitis B virus is an important aetiological factor. Though the number of cases under review is small, universal early vaccination against hepatitis B virus is necessary in Nigerian children in order to reduce the burden of chronic hepatitis B disease and hepatocellular carcinoma.

P53 codon 249 mutation in hepatocellular carcinomas from Nigeria

Mutations of p53 tumour suppressor gene often occur in hepatocellular carcinoma and, in particular, codon 249 hot-spot mutation is displayed by hepatocellular carcinomas occurring in hepatitis B virus-endemic areas with high dietary aflatoxin intake. This study was done to determine the frequency of p53 codon 249 mutation in hepato-cellular carcinoma in Nigerian patients with this tumour. Tumour samples were obtained from 18 Nigerian patients (all from the Southwest of the country) with histologically confirmed hepatocellular carcinoma by autopsy (n = 14), surgical resection (n = 3) and ante-mortem liver biopsy (n = 1). Fourteen of them had co-existing cirrhosis. Amplification of exon 7 of p53 gene from DNA samples of hepatocellular carcinoma tissue was undertaken by nested polymerase chain reaction followed by restriction enzyme analysis. One out of the 18 tumour samples tested (5.5%) demonstrated codon 249 mutation. This study suggests that, in Nigeria, especially the south-western region, aflatoxins appear to play a limited role in hepatocarcinogenesis.

Evidence of a major gene effect for angiotensinogen among Nigerians

To dissect the genetic pathway of hypertension, we measured angiotensinogen in 685 members of 186 families recruited from a rural community in southwest Nigeria. Commingling and segregation analyses were carried out. A mixture of two and/or three distributions fits the data significantly better than a single distribution in commingling analysis, suggesting a major gene effect. Segregation analysis confirmed that a recessive major gene model for low values of angiotensinogen provides the best fit to the data and about 13% of the variance was due to the recessive gene segregation.

Maximum-likelihood generalized heritability estimate for blood pressure in Nigerian families

Elevated blood pressure (BP) is more common in relatives of hypertensives than in relatives of normotensives, indicating familial resemblance of the BP phenotypes. Most published studies have been conducted in westernized societies. To assess the ability to generalize these estimates, we examined familial patterns of BP in a population-based sample of 510 nuclear families, including 1552 individuals (320 fathers, 370 mothers, 475 sons, and 387 daughters) from Ibadan, Nigeria. The prevalence of obesity in this community is low (body mass index: fathers, 21.6; mothers, 23.6; sons, 19.2; and daughters=21.0 kg/m2). The BP phenotype used in all analyses was created from the best regression model by standardizing the age-adjusted systolic blood pressure (SBP) and diastolic blood pressure (DBP) to 0 mean and unit variance. Heritability was estimated by use of the computer program SEGPATH from the most parsimonious model of "no spouse and neither gender nor generation difference" as 45% for SBP and 43% for DBP. The lack of a significant spouse correlation is consistent with little or no influence of the common familial environment. However, the heritability estimate of <50% for both SBP and DBPs reinforces the importance of the nonshared environmental effect.

Angiotensinogen levels and obesity in four black populations. ICSHIB Investigators

BACKGROUND

The relationship between circulating levels of angiotensinogen and hypertension in the epidemiologic setting has not been studied much. Recent findings related to the association between hypertension and polymorphisms of the angiotensinogen gene have generated new interest in this potential pathway to hypertension.

OBJECTIVES

To examine environmental factors associated with levels of circulating angiotensinogen as determinants of hypertension in populations of African origin.

METHODS

We recruited 1557 participants from communities in Nigeria (n = 611), Zimbabwe (n = 161), Jamaica (n = 476), and Maywood, Illinois, USA (n = 309).

RESULTS

Mean angiotensinogen levels varied widely across groups (Nigeria 1381 ng/ml angiotensin I generated, Zimbabwe 1638 ng/ml angiotensin I generated, Jamaica 1808 ng/ml angiotensin I generated, and Maywood 2039 ng/ml angiotensin I generated). Average body mass index was highly correlated to angiotensinogen level across the population samples, accounting for 90% of the between-sample variation. At the individual level the correlation between body mass index and angiotensinogen level was substantially smaller, in the range 0.04-0.15, although the association attained statistical significance for all but one of the populations. Women had higher levels of angiotensinogen and mean levels in subjects of both sexes declined in late middle age. Hypertensives also had significantly higher levels of angiotensinogen and we noted correlations to blood pressure for two of the four populations.

CONCLUSION

Obesity, sex and age would all appear to be important modifiers of circulating angiotensinogen levels. The variation in level across populations was substantially larger than that which has been found previously in association with known genetic polymorphisms within populations, suggesting the possibility that environmental effects are more important than had previously been recognized.

Leptin and body composition of Nigerians, Jamaicans, and US blacks

The role of leptin in humans remains controversial. Leptin concentrations are highly correlated with body fat stores. We tested whether or not this relation was consistent across the range of body composition encompassing the lean as well as the obese. Individuals participating in community-based comparative research in Nigeria (n = 363), Jamaica (n = 372), and the United States (Maywood, IL; n = 699) had their plasma leptin concentrations and body compositions (with bioelectrical impedance analysis) measured. All participants identified themselves as being black. Body mass index (in kg/m2) ranged from 14 to 62. Large differences in mean plasma leptin were noted across populations for both men and women in Nigeria, Jamaica, and the United States, respectively (men: 2.8, 3.9, and 6.8 microg/L; women: 10.3, 18.6, and 27.7 microg/L). An exponential function fit the relation between percentage body fat or total fat mass and leptin for men and women at each site. For women and men the exponential function with either percentage body fat or total fat mass was of the same shape, but increased by a constant in women, yielding higher leptin concentrations than in men at every level of body fat. On the basis of this broad distribution of body composition, the data suggest an exponential response of leptin to increases in body fat stores, consistent with the development of leptin resistance in individuals developing obesity. These findings likewise confirm that men and women exhibit different set points in terms of leptin production.

Hypertension, serum angiotensinogen, and molecular variants of the angiotensinogen gene among Nigerians

BACKGROUND

We evaluated the association among the M235T and T174M variants of the angiotensinogen (AGT) gene, plasma AGT, and hypertension status in a sample of Nigerians.

METHODS AND RESULTS

Participants were selected from the extremes of the blood pressure distribution obtained from the population survey of 2509 men and women aged 25 to 74 years. Cases (hypertensive subjects) were individuals who had high blood pressure or were taking antihypertensive medication, and control subjects were individuals with low blood pressure who had never taken antihypertensive medication. We found a significant association between the M235T variant and plasma AGT level. Hypertensive subjects had higher plasma AGT levels compared with control subjects. The allele frequencies of the two variants were similar in the hypertensive patients and the control subjects.

CONCLUSIONS

The consistent relationships observed between the M235T variant and the protein product and between plasma level of the protein and hypertension status in different ethnic groups provide some evidence for a biochemical mechanism linking DNA variation in the renin-angiotensin system with the hypertension phenotype.

Polymorphisms of renin-angiotensin genes among Nigerians, Jamaicans, and African Americans

Within the context of an international collaborative study of the evolution of hypertension in the black diaspora, we determined the allelic distribution of hypertension candidate genes for the renin-angiotensin system in three populations of African origin. The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) and the M235T and T174M variants of the angiotensinogen (AGT) gene were examined in individuals from Nigeria, Jamaica, and the United States. Large differences in the prevalence of hypertension were recorded in door-to-door surveys, ranging from 16% in Nigeria to 33% in the United States. The frequency of the D allele was similar in all groups (54%, 59%, and 63% in Nigeria, Jamaica, and the United States, respectively). The 235T allele of the AGT gene was found in 81% of US and Jamaican blacks and 91% of Nigerians; very little variation was seen for the T174M marker. Despite large differences in hypertension rates, genetic variation at the index loci among these groups was modest. Overall, the frequency of the ACE*D allele was only slightly higher than that reported for European and Japanese populations, whereas the AGT 235T allele was twice as common. Compared with blacks in the western hemisphere, Nigerians had a higher frequency of the 235T allele, which is consistent with 25% European admixture in Jamaica and the United States. The results indicate the potential for etiologic heterogeneity in genetic factors related to hypertension across ethnic groups while suggesting that environmental exposures most likely explain the gradient in risk in the comparison among black populations.

Characterization of 2-amino-1-benzylbenzimidazole and its metabolites using tandem mass spectrometry

We have investigated the in vitro hamster hepatic microsomal metabolism of the amino-azaheterocycle, 2-amino-1-benzylbenzimidazole (ABB). Three major metabolites were isolated and structurally characterized, using a combination of off-line HPLC, in conjunction with both electron ionization and fast atom bombardment ionization tandem mass spectrometry. ABB was shown to be debenzylated to afford 2-aminobenzimidazole (AB), as well as N- and C-oxidized to give 1-benzyl-N2-hydroxyaminobenzimidazole (BHB) and 2-amino-1-benzyl-hydroxybenzimidazole, respectively. The possible reasons for formation of the exocyclic hydroxylamine BHB are discussed. Furthermore, ABB is proposed as a suitable model compound for investigating parameters that control formation of toxic hydroxylamines derived from amino-azaheterocycles.

Reaction of human lungs to aspirated animal fat (ghee): a clinicopathological study

We report the clinical findings and pathological lung changes in four children following a cultural practice of forced feeding with animal fat (ghee) during infancy. The clinical presentation was of acute or chronic chest infection which failed to respond to antimicrobial therapy. The radiographic features ranged from extensive bronchopneumonia to collapse/consolidation and bronchiectasis. The light microscopy findings included diffuse mononuclear interstitial pneumonia, intraalveolar desquamation of pneumocytes, lipid granuloma formation, lung atelectasis and bronchiectasis. In the two children with longstanding reactions, the striking feature was the minimal lipid engulfment by the macrophages, the continuation of the mononuclear interstitial pneumonia, bronchiectasis and minimal lung fibrosis. In these two older children, the lung lymphatics were probably the main channels for drainage of the aspirated ghee.

Respiratory distress in a special care baby unit in Nigeria

Although respiratory distress is common among African newborn infants in special care, respiratory distress syndrome, which is the commonest cause of respiratory distress in other races, has been reported as uncommon among African infants. A prospective study of 312 consecutive newborn Nigerian infants admitted to a special care unit revealed 103 (33%) with respiratory distress. In 100 cases studied there was transient tachypnoea of the newborn ( TTN ) in 40% while specific diseases such as pneumonia and septicaemia, severe aspiration syndromes and respiratory distress syndrome (RDS) accounted for 25%, 19% and 12%, respectively. TTN and RDS occurred mostly among preterm infants with moderate perinatal asphyxia while severe aspiration syndrome was found among term infants with severe birth asphyxia. The study suggests that prevention and/or improved management of perinatal asphyxia and infections should reduce the incidence and mortality associated with neonatal respiratory distress.

Recovery of renal function after 33 days of complete bilateral ureteric obstruction

Bilateral ureteric ligation is a rare complication of hysterectomy. We report a case of prompt recovery of renal function following release of bilateral ureteric ligation persisting for 33 days.

Biliary lithiasis associated with ascariasis in a Nigerian woman

We report the occurrence of gallstones and intrahepatic stones in association with ascarid invasion of the biliary tract in a 51-year-old Nigerian woman. Although biliary stones are known to be caused by products of Ascaris worms, no etiological association was demonstrable in this case. Invasion of the biliary tract by Ascaris worms is reported as rare in our environment where intestinal ascariasis is extremely common. It is suggested that the rarity is apparent rather than real and that it is important to bear this condition in mind in view of modern rapid migration of populations.