Use of super resolution reconstruction MRI for surgical planning in Placenta accreta spectrum disorder: Case series

INTRODUCTION

Comprehensive imaging using ultrasound and MRI of placenta accreta spectrum (PAS) aims to prevent catastrophic haemorrhage and maternal death. Standard MRI of the placenta is limited by between-slice motion which can be mitigated by super-resolution reconstruction (SRR) MRI. We applied SRR in suspected PAS cases to determine its ability to enhance anatomical placental assessment and predict adverse maternal outcome.

METHODS

Suspected PAS patients (n = 22) underwent MRI at a gestational age (weeks + days) of (32+3±3+2, range (27+1-38+6)). SRR of the placental-myometrial-bladder interface involving rigid motion correction of acquired MRI slices combined with robust outlier detection to reconstruct an isotropic high-resolution volume, was achieved in twelve. 2D MRI or SRR images alone, and paired data were assessed by four radiologists in three review rounds. All radiologists were blinded to results of the ultrasound, original MR image reports, case outcomes, and PAS diagnosis. A Random Forest Classification model was used to highlight the most predictive pathological MRI markers for major obstetric haemorrhage (MOH), bladder adherence (BA), and placental attachment depth (PAD).

RESULTS

At delivery, four patients had placenta praevia with no abnormal attachment, two were clinically diagnosed with PAS, and six had histopathological PAS confirmation. Pathological MRI markers (T2-dark intraplacental bands, and loss of retroplacental T2-hypointense line) predicting MOH were more visible using SRR imaging (accuracy 0.73), in comparison to 2D MRI or paired imaging. Bladder wall interruption, predicting BA, was only easily detected by paired imaging (accuracy 0.72). Better detection of certain pathological markers predicting PAD was found using 2D MRI (placental bulge and myometrial thinning (accuracy 0.81)), and SRR (loss of retroplacental T2-hypointense line (accuracy 0.82)).

DISCUSSION

The addition of SRR to 2D MRI potentially improved anatomical assessment of certain pathological MRI markers of abnormal placentation that predict maternal morbidity which may benefit surgical planning.

Intravenous thrombolysis for multi-ethnic Asians with acute ischaemia stroke in Malaysian public primary stroke centres versus acute stroke ready hospitals: Comparison of real-world clinical outcomes

INTRODUCTION

Intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator is beneficial in acute ischaemic stroke (AIS). We aim to compare the realworld clinical outcomes and service efficiency of IVT in Malaysian primary stroke centres (PSCs) versus acute stroke ready hospitals (ASRHs).

MATERIALS AND METHODS

We conducted a multi-centre cohort study involving 5 PSCs and 7 ASRHs in Malaysia. Through review of medical records of AIS patients who received IVT from 01 January 2014 to 30 June 2021, real-world data was extracted for analysis. Univariate and multivariate regression models were employed to evaluate the role of PSCs versus ASRHs in post-IVT outcomes and complications. Statistical significance was set at p<0.05.

RESULTS

A total of 313 multi-ethnic Asians, namely 231 from PSCs and 82 from ASRHs, were included. Both groups were comparable in baseline demographic, clinical, and stroke characteristics. The efficiency of IVT delivery (door-toneedle time), functional outcomes (mRS at 3 months post- IVT), and rates of adverse events (intracranial haemorrhages and mortality) following IVT were comparable between the 2 groups. Notably, 46.8% and 48.8% of patients in PSCs and ASRHs group respectively (p=0.752) achieved favourable functional outcome (mRS≤1 at 3 months post-IVT). Regression analyses demonstrated that post-IVT functional outcomes and adverse events were independent of the role of PSCs or ASRHs.

CONCLUSION

Our study provides real-world evidence which suggests that IVT can be equally safe, effective, and efficiently delivered in ASRHs. This may encourage the establishment of more ASRHs to extend the benefits of IVT to a greater proportion of stroke populations and enhance the regional stroke care.

An analog-AI chip for energy-efficient speech recognition and transcription

Models of artificial intelligence (AI) that have billions of parameters can achieve high accuracy across a range of tasks1,2, but they exacerbate the poor energy efficiency of conventional general-purpose processors, such as graphics processing units or central processing units. Analog in-memory computing (analog-AI)3-7 can provide better energy efficiency by performing matrix-vector multiplications in parallel on 'memory tiles'. However, analog-AI has yet to demonstrate software-equivalent (SWeq) accuracy on models that require many such tiles and efficient communication of neural-network activations between the tiles. Here we present an analog-AI chip that combines 35 million phase-change memory devices across 34 tiles, massively parallel inter-tile communication and analog, low-power peripheral circuitry that can achieve up to 12.4 tera-operations per second per watt (TOPS/W) chip-sustained performance. We demonstrate fully end-to-end SWeq accuracy for a small keyword-spotting network and near-SWeq accuracy on the much larger MLPerf8 recurrent neural-network transducer (RNNT), with more than 45 million weights mapped onto more than 140 million phase-change memory devices across five chips.

A Multi-purpose Realistic Haze Benchmark with Quantifiable Haze Levels and Ground Truth

Imagery collected from outdoor visual environments is often degraded due to the presence of dense smoke or haze. A key challenge for research in scene understanding in these degraded visual environments (DVE) is the lack of representative benchmark datasets. These datasets are required to evaluate state-of-the-art object recognition and other computer vision algorithms in degraded settings. In this paper, we address some of these limitations by introducing the first realistic haze image benchmark, from both aerial and ground view, with paired haze-free images, and in-situ haze density measurements. This dataset was produced in a controlled environment with professional smoke generating machines that covered the entire scene, and consists of images captured from the perspective of both an unmanned aerial vehicle (UAV) and an unmanned ground vehicle (UGV). We also evaluate a set of representative state-of-the-art dehazing approaches as well as object detectors on the dataset. The full dataset presented in this paper, including the ground truth object classification bounding boxes and haze density measurements, is provided for the community to evaluate their algorithms at: https://a2i2-archangel.vision. A subset of this dataset has been used for the "Object Detection in Haze" Track of CVPR UG2 2022 challenge at http://cvpr2022.ug2challenge. org/track1.html.

Abstract 5426: Multi-omic characterization and predictive features of advanced ovarian cancer patients in a large phase III cohort

Discovery and validation of biomarkers derived from multi-dimensional clinico-genomic datasets have become critical in precision medicine and oncology drug development. The integration of multi-dimensional genomic and imaging datasets from patients in late-stage oncology clinical trials can be difficult, in part due to limited patient enrollment and sample collection, especially tumor tissue biopsies. The objective of this project was to conduct predictive biomarker discovery on integrated clinico-genomics data spanning tumor genomics, germline genetics, tumor imaging, and circulating blood-based biomarkers for a cohort of 800+ advanced ovarian cancer patients enrolled in the phase III trial of the PARP-1 inhibitor Veliparib (VELIA). Genomic (DNA & RNA) and imaging datasets were generated from 800+ patient-matched tumor biopsies, liquid biopsies and whole blood to enable various biomarker analyses for this study, notably in BRCA-deficient and HRD+ subgroups. Pairwise analysis of individual features with clinical outcomes shows that increased tumor-mutation burden (TMB), RNA-based estimates of immune activity (ICR and MIRACLE scores), CA-125 elimination constant (KELIM score), and image-based estimates tumor-infiltrating lymphocytes (TILs) were each significantly associated with longer PFS and less progressive disease (PD). Similarly, homologous recombination deficiency (HRD) and BRCA alteration were associated with better clinical outcomes, while high CA-125 was associated with worse outcomes. To understand the concerted impact of these features on clinical outcome, we developed multivariate classifiers of PD and regressors (Cox Proportional Hazards) of PFS using XGBoost; using a train-test split of 75/25, we trained the models with 500 rounds of 10-fold cross validation hyperparameter tuning, which resulted in fit models. The PD classifier achieved a validation accuracy of 0.71 and F1-score of 0.78, with high immune activation, high TMB, high KELIM, and HRD and BRCA alteration predicting better outcomes. The PFS survival model achieved a validation C-index of 0.61, with a rank importance of features similar to that of PD classification models; for both models, patients receiving Veliparib had clear benefit relative to that of control arms. Collectively, this study illustrates the value of integrating multi-dimensional datasets with predictive machine learning to identify clinically-relevant biomarkers.

CR, DM, PA, BR, JD, TB, PN, JS, XH, and JFW are employees of AbbVie. RLC an employee at The University of Texas MD Anderson Cancer Center and has no funding to disclose. The design, study conduct, and financial support for this research were provided by AbbVie. AbbVie participated in the interpretation of data, review, and approval of the publication.

Citation Format: Cyril Ramathal, David Masica, Peter Ansell, Bridget Riley-Gillis, Jacob Degner, Thanh Bui, Priya Narayanan, Josue Samayoa, Xin Huang, Robert F. Coleman, Jeffrey F. Waring. Multi-omic characterization and predictive features of advanced ovarian cancer patients in a large phase III cohort. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5426.

Detection of acute promyelocytic leukemia in peripheral blood and bone marrow with annotation-free deep learning

While optical microscopy inspection of blood films and bone marrow aspirates by a hematologist is a crucial step in establishing diagnosis of acute leukemia, especially in low-resource settings where other diagnostic modalities are not available, the task remains time-consuming and prone to human inconsistencies. This has an impact especially in cases of Acute Promyelocytic Leukemia (APL) that require urgent treatment. Integration of automated computational hematopathology into clinical workflows can improve the throughput of these services and reduce cognitive human error. However, a major bottleneck in deploying such systems is a lack of sufficient cell morphological object-labels annotations to train deep learning models. We overcome this by leveraging patient diagnostic labels to train weakly-supervised models that detect different types of acute leukemia. We introduce a deep learning approach, Multiple Instance Learning for Leukocyte Identification (MILLIE), able to perform automated reliable analysis of blood films with minimal supervision. Without being trained to classify individual cells, MILLIE differentiates between acute lymphoblastic and myeloblastic leukemia in blood films. More importantly, MILLIE detects APL in blood films (AUC 0.94 ± 0.04) and in bone marrow aspirates (AUC 0.99 ± 0.01). MILLIE is a viable solution to augment the throughput of clinical pathways that require assessment of blood film microscopy.

Rac1 controls cell turnover and reversibility of the involution process in postpartum mammary glands

Cell turnover in adult tissues is essential for maintaining tissue homeostasis over a life span and for inducing the morphological changes associated with the reproductive cycle. However, the underlying mechanisms that coordinate the balance of cell death and proliferation remain unsolved. Using the mammary gland, we have discovered that Rac1 acts as a nexus to control cell turnover. Postlactational tissue regression is characterised by the death of milk secreting alveoli, but the process is reversible within the first 48 h if feeding recommences. In mice lacking epithelial Rac1, alveolar regression was delayed. This defect did not result from failed cell death but rather increased cell turnover. Fitter progenitor cells inappropriately divided, regenerating the alveoli, but cell death also concomitantly accelerated. We discovered that progenitor cell hyperproliferation was linked to nonautonomous effects of Rac1 deletion on the macrophageal niche with heightened inflammation. Moreover, loss of Rac1 impaired cell death with autophagy but switched the cell death route to apoptosis. Finally, mammary gland reversibility failed in the absence of Rac1 as the alveoli failed to recommence lactation upon resuckling.

Olfactory dysfunction amongst children and adolescents with laboratory confirmed coronavirus disease 2019: a systematic review

BACKGROUND

Despite the rapidly emerging reports of olfactory dysfunction amongst adult patients with coronavirus disease 2019, cases involving children and adolescents are scarcely reported. The literature was reviewed to elucidate olfactory dysfunction amongst children and adolescents with coronavirus disease 2019.

METHODS

A search of the literature published from 1 December 2019 to 30 April 2021 was conducted using four databases, based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. The search was performed over one month (May 2021).

RESULTS

Only 9 articles were identified, with a total of 316 laboratory confirmed coronavirus disease 2019 positive children and adolescents, of whom 156 reported olfactory dysfunction. Four studies reported olfactory dysfunction based on subjective tests; four studies carried out objective assessment. Most studies reported on olfaction recovery.

CONCLUSION

The literature review revealed an olfactory dysfunction rate of 49 per cent amongst children and adolescents with coronavirus disease 2019. Persistence of olfactory dysfunction was reported in 7.1 per cent of the patients. Further studies involving objective measures need to be carried out in children and adolescents with coronavirus disease 2019.

Aberrantly low STAT3 and STAT5 responses are associated with poor outcome and an inflammatory gene expression signature in pediatric acute myeloid leukemia

The relapse rate for children with acute myeloid leukemia is nearly 40% despite aggressive chemotherapy and often stem cell transplant. We sought to understand how environment-induced signaling responses are associated with clinical response to treatment. We previously reported that patients whose AML cells showed low G-CSF-induced STAT3 activation had inferior event-free survival compared to patients with stronger STAT3 responses. Here, we expanded the paradigm to evaluate multiple signaling parameters induced by a more physiological stimulus. We measured STAT3, STAT5 and ERK1/2 responses to G-CSF and to stromal cell-conditioned medium for 113 patients enrolled on COG trials AAML03P1 and AAML0531. Low inducible STAT3 activity was independently associated with inferior event-free survival in multivariate analyses. For inducible STAT5 activity, those with the lowest and highest responses had inferior event-free survival, compared to patients with intermediate STAT5 responses. Using existing RNA-sequencing data, we compared gene expression profiles for patients with low inducible STAT3/5 activation with those for patients with higher inducible STAT3/5 signaling. Genes encoding hematopoietic factors and mitochondrial respiratory chain subunits were overexpressed in the low STAT3/5 response groups, implicating inflammatory and metabolic pathways as potential mechanisms of chemotherapy resistance. We validated the prognostic relevance of individual genes from the low STAT3/5 response signature in a large independent cohort of pediatric AML patients. These findings provide novel insights into interactions between AML cells and the microenvironment that are associated with treatment failure and could be targeted for therapeutic interventions.

Prevalence of Abnormal Karyotypes among Males with Non-obstructive Azoospermia and Severe Oligozoospermia: A Retrospective Study

Introduction: Chromosomal abnormalities are one of the important causes of male infertility. Numerical and structural chromosomal abnormalities are seen frequently in men with azoospermia and severe oligospermia. Other abnormalities include Y Chromosome Microdeletions (YCMD), Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene mutations affecting the internal ductal system, genes affecting sperm function and other non-specific disorders. Upto 14% of the men with azoospermia and severe oligospermia have karyotypic abnormalities. Aim: To determine the prevalence of abnormal karyotypes among men with azoospermia and severe oligozoospermia (<5 million/mL). Materials and Methods: The present study was a retrospective observational study carried out at the Fertility Clinic, Institute of Maternal and Child Health, Calicut, Kerala, India, on patients who attended the Infertility Department between January 2016 to December 2019. Semen analysis was done on 232 patients with 100 patients of azoospermia and 132 patients of oligozoospermia. Karyotyping was done from the Cytogenetics Unit, Department of Anatomy. The data was entered in MS excel sheet and analysed and results were expressed in percentage. Results: Chromosomal abnormalities were detected in 35 (35%) of 100 azoospermia and 15 (11.3%) of 132 severe oligospermia cases analysed. Klinefelter syndrome was the most common abnormality detected in azoospermia (22/35). A 46XX was found in two cases. Structural abnormalities were detected in three case (46 X, der X, 46XY der Chr 1 and Chr 9 inversion). Small Y was found in three cases. Polymorphic variants were found in five patients (46XY 15pstk+, 46XY 15ps+, 46XY 1qh+, 46XY 9qh+). Small Y was found in one case. In oligozoospermia, autosomal translocations were found in four cases {46XY, t(11;13)(q21;q21.2), 46XY, t(1;9) (p13;p21), 46XY, t(13;15)(q34;q21), 46XY, t(7,14) (q34:q11)}, Derivative (46XY der 15) and Marker chromosome (47XY+mar) in one case each. Klinefelter syndrome was found in two cases and 48XXYY was found in one patient. Polymorphic variants were found in five cases (46XY 21pstk,46XY 15ps+, 46XY 1qh-, 48XY 9qh+). Small Y was found in one case. Conclusion: Sex chromosomal and autosomal abnormalities are found frequently in azoospermia and severe oligospermia and hence, genetic screening and counseling before Intracytoplasmic Sperm Injection (ICSI) is warranted.

Crystal structure determination of two pyridine derivatives: 4-[(E)-2-(4-methoxyphenyl)ethenyl]-1-methylpyridin-1-ium hexafluoro-λ6-phosphane and 4-[(E)-2-[4-(dimethylamino)phenyl]ethenyl]-1-phenyl-1λ5-pyridin-1-ylium hexafluoro-λ6-phosphane

In both title pyridine derivatives, (I) and (II), the cation adopts an E configuration with respect to the C=C. In compound (I), the PF₆⁻ anion is disordered with occupancy factors of 0.614 (7):0.386 (7). In both the compounds, the crystal packing is stabilized by C—H⋯F inter­molecular inter­actions results into two-dimensional mol­ecular sheets, which are formed by (14) ring motifs in compound (I), (40) ring motifs in compound (II). In addition to that, the crystal packing is further stabilized by P—F⋯π inter­actions in compound (I) and π–π in compound (II).

The title mol­ecular salts, C₁₆H₁₆NO⁺·PF₆⁻, (I), and C₂₁H₂₁N₂⁺·PF₆⁻, (II), are pyridine derivatives. In compound (I), the cation comprises a methyl N-substituted pyridine ring and a meth­oxy-substituted benzene ring connected by a C=C double bond. The F atoms of the PF₆⁻ anion are disordered over two sets of sites with refined occupancy factors of 0.614 (7):0.386 (7). In compound (II), the cation comprises a pyridine ring attached to unsubstituted phenyl ring and a di­methyl­aniline ring, which are connected by a C=C double bond. The anion is PF₆⁻. In both salts, the cation adopts an E configuration with respect to the C=C bond. The pyridine ring makes a dihedral angle of 9.86 (12)° with the meth­oxy-substituted benzene ring in compound (I) and 11.2 (3)° with the di­methyl­amine-substituted benzene ring in compound (II). In compound (I), the crystal packing is stabilized by weak C—H⋯F inter­molecular inter­actions which result in R⁴₃(14) ring motifs, forming mol­ecular sheets running parallel to (03). These are further stabilized by weak P—F⋯π interactions. In compound (II), the crystal packing is stabilized by C—H⋯F inter­actions, which result in R⁶₆(40) ring motifs, forming mol­ecular sheets running parallel to (101) and these are further connected by π–π inter­actions.

The role of 18F-FDG PET CT in common gynaecological malignancies

[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography (¹⁸F-FDG PET CT) has increasing clinical applications supplementing conventional TVUS, CT and MRI imaging in assessing ovarian, cervical and endometrial cancer. The published literature on the applications of ¹⁸F-FDG PET CT shows its use can have significant impact on patient management by improving staging of the cancers, influencing patient selection for treatment and in detecting early recurrent disease. However, the increasing clinical use of PET CT does not always align with the guidelines, recommendations or expert opinion in the use of PET CT. This article summarizes the existing evidence base for the established clinical applications and the emerging roles for ¹⁸F-FDG PET CT in the common gynaecological malignancies.

Diagnostic utility of whole body Dixon MRI in multiple myeloma: A multi-reader study

OBJECTIVE

To determine which of four Dixon image types [in-phase (IP), out-of-phase (OP), fat only (FO) and water-only (WO)] is most sensitive for detecting multiple myeloma (MM) focal lesions on whole body MRI (WB-MRI) images.

METHODS

Thirty patients with clinically-suspected MM underwent WB-MRI at 3 Tesla. Unenhanced IP, OP, FO and WO Dixon images were generated and read by four radiologists. On each image type, each radiologist identified and labelled all visible myeloma lesions in the bony pelvis. Each identified lesion was compared with a reference standard consisting of pre- and post-contrast Dixon and diffusion weighted imaging (read by a further consultant radiologist) to determine whether the lesion was truly positive. Lesion count, true positives, sensitivity, and positive predictive value were compared across the four Dixon image types.

RESULTS

Lesion count, true positives, sensitivity and confidence scores were all significantly higher on FO images than on IP images (p>0.05).

DISCUSSION

FO images are more sensitive than other Dixon image types for MM focal lesions, and should be preferentially read by radiologists to improve diagnostic accuracy and reporting efficiency.

Crystal structures of three 1-oxo-1,2-dihydronaphthalene derivatives: dimethyl 4-(4-methoxyphenyl)-2-(4-methylphenyl)-1-oxo-1,2-dihydronaphthalene-2,3-dicarboxylate, dimethyl 1-oxo-2-(pyren-4-yl)-4-(thiophen-2-yl)-1,2-dihydronaphthalene-2,3-dicarboxylate and ethyl 1-oxo-2-phenyl-2,4-bis(thiophen-2-yl)-1,2-dihydronaphthalene-3-carboxylate

In the title 1-oxo-1,2-di­hydro­naphthalene derivatives, the cyclo­hexa-1,3-diene rings of the 1,2-di­hydro­naphthalene ring systems adopt half-chair, boat and half-chair conformations, respectively. In the crystal of the methyl­phenyl compound, the mol­ecules are linked via C—H⋯O, C—H⋯π and π–π inter­actions, forming a double-chain structure, while in the crystals of the other two compounds, mol­ecules are linked by π–π inter­actions, forming a chain structure.

In the title 1-oxo-1,2-di­hydro­naphthalene derivatives, C₂₈H₂₄O₆, (I), C₃₄H₂₂O₅S, (II), and C₂₇H₂₀O₃S₂, (III), the cyclo­hexa-1,3-diene rings of the 1,2-di­hydro­naphthalene ring systems adopt half-chair, boat and half-chair conformations, respectively. The carbonyl O atoms attached to the di­hydro­naphthalene ring systems are each significantly deviated from the mean plane of the 1,2-di­hydro­naphthalene ring system, by 0.6162 (12) Å in (I), 0.6016 (16) Å in (II) and 0.515 (3) Å in (III). The mean planes of the 1,2-di­hydro­naphthalene ring systems make dihedral angles of 85.83 (3), 88.19 (3) and 81.67 (8)°, respectively, with the methyl­phenyl ring in (I), the pyrene ring in (II) and the phenyl ring in (III). In (I), the mol­ecular structure is stabilized by an intra­molecular C—H⋯O hydrogen bond, generating an S(6) ring motif. In the crystal of (I), mol­ecules are linked by an inter­molecular C—H⋯O hydrogen bond, which generates a C(8) zigzag chain running along [100]. Adjacent chains are further connected by C—H⋯π and offset π–π inter­actions [centroid–centroid distance = 3.6572 (9) Å], forming a double-chain structure. In the crystals of (II) and (III), mol­ecules are linked into chain structures by offset π–π inter­actions with centroid–centroid distances of 3.5349 (12) and 3.8845 (13) Å for (II) and 3.588 (2) Å for (III). In (II) and (III), the thio­phene rings are orientationally disordered over two sites, with occupancy ratios of 0.69:0.31 for (II), and 0.528 (4):0.472 (4) and 0.632 (5):0.368 (5) for (III).

Crystal structures of three carbazole derivatives: 12-ethyl-7-phenylsulfonyl-7H-benzofuro[2,3-b]carbazole, (1), 2-(4,5-dimethoxy-2-nitrophenyl)-4-hydroxy-9-phenylsulfonyl-9H-carbazole-3-carbaldehyde, (2), and 12-phenyl-7-phenylsulfonyl-7H-benzofuro[2,3-b]carbazole, (3)

The three title compounds, C26H19NO3S, (1), C27H20N2O8S, (2), and C30H19NO3S, (3), are carbazole derivatives, where (1) and (3) are heterocycle-containing carbazoles with a benzofuran moiety fused to a carbazole unit. In (2), a dimethoxynitrophenyl ring is attached to the carbazole moiety. In the three derivatives, a phenylsulfonyl group is attached to the N atom of the carbazole unit. Compound (1) crystallizes with two independent molecules in the asymmetric unit (AandB). The carbazole skeleton in the three compounds is essentially planar. In compound (1), the benzene ring of the phenylsulfonyl moiety is almost orthogonal to the carbazole moiety, with dihedral angles of 85.42 (9) and 84.52 (9)° in moleculesAandB, respectively. The benzene ring of the phenylsulfonyl group in compounds (2) and (3) are inclined to the carbazole moiety, making dihedral angles of 70.73 (13) and 81.73 (12)°, respectively. The S atom has a distorted tetrahedral configuration in all three compounds. In the crystals, C—H...O hydrogen bonds give rise toR22(12) inversion dimers for compound (1), and toR22(24) inversion dimers andR44(40) ring motifs for compound (2). The crystal packing in (1) also features C—H...π and π–π interactions [shortest intercentroid distance = 3.684 (1) Å], leading to supramolecular three-dimensional aggregation. In the crystal of compound (2), the combination of the various C—H...O hydrogen bonds leads to the formation of a three-dimensional network. In the crystal of compound (3), molecules are linked by C—H...O hydrogen bonds, forming chains running parallel to theaaxis, and the chains are linked by C—H...π interactions, forming corrugated sheets parallel to theabplane.

Crystal structures of two new carbazole derivatives: 12-(4-nitrophenyl)-7-phenylsulfonyl-7H-benzofuro[2,3-b]carbazole and 2-methyl-4-(4-nitrophenyl)-9-phenylsulfonyl-9H-thieno[2,3-b]carbazole

The title compounds are carbazole derivatives, with a benzo­furan ring system in (I) and a methyl­thio­phene ring in (II) fused with the respective carbazole moiety. In the crystals of both compounds, mol­ecules are linked via C—H⋯O hydrogen bonds, forming sheets lying parallel to (10).

The title compounds, C₃₀H₁₈N₂O₅S, (I), and C₂₇H₁₈N₂O₄S₂, (II), are carbazole derivatives with a phenyl­sulfonyl group and a nitro­phenyl group attached to the carbazole moiety in identical positions in both mol­ecules. A benzo­furan ring system in (I) and a methyl­thio­phene ring in (II) are fused with the respective carbazole moieties on the same sides. The mean plane of the carbazole ring system makes a dihedral angle of 3.17 (7)° with the benzo­furan ring system in (I) and a dihedral angle of 3.39 (11)° with the methyl­thio­phene ring in (II), implying that both fused units are essentially planar. The mean planes of the carbazole ring systems in both the compounds are almost orthogonal to the respective nitro-substituted phenyl rings, making dihedral angles of 75.64 (10) and 77.63 (12)° in compounds (I) and (II), respectively. In (I), the phenyl­sulfonyl ring system is positionally disordered with a refined occupancy ratio of 0.63 (2):0.37 (2). In both compounds, the mol­ecular structures are stabilized by intra­molecular C—H⋯O hydrogen bonds, generating S(6) ring motifs with the sulfone group O atoms. In the crystal of compound (I), mol­ecules are linked by pairs of C—H⋯O hydrogen bonds, which generate R₂²(18) inversion dimers, and inter­connected by C(14) chains running along the c-axis direction, whereas in compound (II), the C—H⋯O hydrogen bonds generate R₄³(37) ring motifs. In the crystals of both compounds, C—H⋯O hydrogen-bonded sheets are formed lying parallel to (10-1). In addition, C—H⋯π and offset π–π inter­actions [inter­centroid distance = 3.7158 (14) Å in (I) and 3.9040 (15) Å in (II)] are also present in the crystals of both compounds.

Comparison of nested-multiplex, Taqman & SYBR Green real-time PCR in diagnosis of amoebic liver abscess in a tertiary health care institute in India

BACKGROUND & OBJECTIVES

Amoebiasis is a common parasitic infection caused by Entamoeba histolytica and amoebic liver abscess (ALA) is the most common extraintestinal manifestation of amoebiasis. The aim of this study was to standardise real-time PCR assays (Taqman and SYBR Green) to detect E. histolytica from liver abscess pus and stool samples and compare its results with nested-multiplex PCR.

METHODS

Liver abscess pus specimens were subjected to DNA extraction. The extracted DNA samples were subjected to amplification by nested-multiplex PCR, Taqman (18S rRNA) and SYBR Green real-time PCR (16S-like rRNA assays to detect E. histolytica/E. dispar/E. moshkovskii). The amplification products were further confirmed by DNA sequence analysis. Receiver operator characteristic (ROC) curve analysis was done for nested-multiplex and SYBR Green real-time PCR and the area under the curve was calculated for evaluating the accuracy of the tests to dignose ALA.

RESULTS

In all, 17, 19 and 25 liver abscess samples were positive for E. histolytica by nested-multiplex PCR, SYBR Green and Taqman real-time PCR assays, respectively. Significant differences in detection of E. histolytica were noted in the real-time PCR assays evaluated ( P<0.0001). The nested-multiplex PCR, SYBR Green real-time PCR and Taqman real-time PCR evaluated showed a positivity rate of 34, 38 and 50 per cent, respectively. Based on ROC curve analysis (considering Taqman real-time PCR as the gold standard), it was observed that SYBR Green real-time PCR was better than conventional nested-multiplex PCR for the diagnosis of ALA.

INTERPRETATION & CONCLUSIONS

Taqman real-time PCR targeting the 18S rRNA had the highest positivity rate evaluated in this study. Both nested multiplex and SYBR Green real-time PCR assays utilized were evaluated to give accurate results. Real-time PCR assays can be used as the gold standard in rapid and reliable diagnosis, and appropriate management of amoebiasis, replacing the conventional molecular methods.

OX40 Ligand Contributes to Human Lupus Pathogenesis by Promoting T Follicular Helper Response

Increased activity of T follicular helper (Tfh) cells plays a major pathogenic role in systemic lupus erythematosus (SLE). However, the mechanisms that cause aberrant Tfh cell responses in SLE remain elusive. Here we showed the OX40 ligand (OX40L)-OX40 axis contributes to the aberrant Tfh response in SLE. OX40L was expressed by myeloid antigen-presenting cells (APCs), but not B cells, in blood and in inflamed tissues in adult and pediatric SLE patients. The frequency of circulating OX40L-expressing myeloid APCs positively correlated with disease activity and the frequency of ICOS(+) blood Tfh cells in SLE. OX40 signals promoted naive and memory CD4(+) T cells to express multiple Tfh cell molecules and were sufficient to induce them to become functional B cell helpers. Immune complexes containing RNA induced OX40L expression on myeloid APCs via TLR7 activation. Our study provides a rationale to target the OX40L-OX40 axis as a therapeutic modality for SLE.

Crystal structures and conformations of two Diels-Alder adduct derivatives: 1,8-bis-(thio-phen-2-yl)-14-oxa-tetra-cyclo-[6.5.1.0(2,7).0(9,13)]tetra-deca-2(7),3,5-trien-10-one and 1,8-diphenyl-14-oxa-tetra-cyclo[6.5.1.0(2,7).0(9,13)] tetra-deca-2,4,6-trien-10-one

The title compounds, C21H16O2S2 (I) and C25H20O2 (II), are products of a tandem 'pincer' Diels-Alder reaction consisting of [2 + 2] cyclo-additions between benzo[c]furan and cyclo-penta-none. Each comprises a fused tetra-cyclic ring system containing two five-membered rings (in envelope conformations with the O atom as the flap) and six-membered rings (in boat conformations). In addition, two thio-phene rings in (I) and two phenyl rings in (II) are attached to the tetra-cyclic ring system. The cyclo-penta-none ring adopts a twisted conformation in (I) and an envelope conformation in (II). In (I), the thio-phene rings are positionally disordered over two sets of sites, with occupancy ratios of 0.901 (2):0.099 (2) and 0.666 (2):0.334 (2). In (II), the oxygen atom of the cyclo-penta-none ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4). The mol-ecular structure of (I) is stabilized by an intra-molecular C-H⋯O hydrogen bond, which generates an S(7) ring motif. In the crystal, the mol-ecules are linked via weak C-H⋯O hydrogen bonds, which generate R (2) 2(16) ring motifs in (I) and C(8) chains in (II). In both structures, the crystal packing also features C-H⋯π inter-actions. The crystal studied of compound (I) was twinned by non-merohedry. The twin component is related by the twin law [-1 0 0 -0.101 1 -0.484 0 0 -1] operated by a twofold rotation axis parallel to the b axis. The structure of (I) was refined with a twin scale factor of 0.275 (2).

A case of pediatric acute lymphoblastic leukemia with invasive candidiasis: short review

Mortality rate associated with invasive fungal infections is very high. Early suspicion for fungal infections is important during intensive chemotherapy for acute leukemia. Empirical treatment with antifungals amphotericin B or caspofungin should be started if patient is not responding to broad spectrum antibiotics and if expected duration of neutropenia is prolonged. We are reporting a 3 years old girl child with diagnosis of pre-B acute lymphoblastic leukemia who developed invasive candidiasis with typical clinical and radiological findings during induction chemotherapy. Candida non-albicans was isolated and she was treated with amphotericin B followed by caspofungin. Patient deteriorated after initial response and succumbed to death. Species identification and sensitivity pattern of fungus can help in selecting appropriate antifungal drug.

Timing of motor cortical stimulation during planar robotic training differentially impacts neuroplasticity in older adults

OBJECTIVE

The objective was to determine how stimulation timing applied during reaching influenced neuroplasticity related to practice. Older adult participants were studied to increase relevance for stroke rehabilitation and aging.

METHODS

Sixteen participants completed 3 sessions of a reaching intervention with 480 planar robotic movement trials. Sub-threshold, single-pulse transcranial magnetic stimulations (TMS) were delivered during the late reaction time (LRT) period, when muscle activity exceeded a threshold (EMG-triggered), or randomly. Assessments included motor evoked potentials (MEP), amplitude, and direction of supra-threshold TMS-evoked movements and were calculated as change scores from baseline.

RESULTS

The direction of TMS-evoked movements significantly changed after reaching practice (p<0.05), but was not significantly different between conditions. Movement amplitude changes were significantly different between conditions (p<0.05), with significant increases following the LRT and random conditions. MEP for elbow extensors and flexors, and the shoulder muscle that opposed the practice movement were significantly different between conditions with positive changes following LRT, negative changes following EMG-triggered, and no changes following the random condition. Motor performance including movement time and peak velocity significantly improved following the training but did not differ between conditions.

CONCLUSIONS

The responsiveness of the motor cortex to stimulation was affected positively by stimulation during the late motor response period and negatively during the early movement period, when stimulation was combined with robotic reach practice.

SIGNIFICANCE

The sensitivity of the activated motor cortex to additional stimulation is highly dynamic.

Crystal structure of 2,9-diphenyl-17λ6-thiatetracyclo[8.7.0.03,8.011,16]heptadeca-1(10),2,4,6,8,11(16),12,14-octaene-17,17-dione

The title compound, C₂₈H₁₈O₂S, is composed of a naphthalene ring system fused with a benzo­thio­phene ring and attached to two phenyl rings. The phenyl rings make dihedral angles of 70.92 (8) and 79.23 (8)° with the essentially planar naphthalene ring system (r.m.s. deviation = 0.031 Å). There is an intra­molecular C—H⋯π inter­action present. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds which generate C(7) zigzag chains running parallel to [10-1]. The chains are linked via further C—H⋯π inter­actions, forming a three-dimensional structure.

3,10,14,21-Tetra-kis(4-meth-oxy-phen-yl)penta-cyclo-[11.8.0.0(2,11).0(4,9).0(15,20)]henicosa-1(21),2,4(9),5,7,10,13,15(20),16,18-decaen-12-one chloro-form monosolvate

The asymmetric unit of the title compound, C₄₉H₃₆O₆·CHCl₃, contains half an organic mol­ecule, the complete mol­ecule being generated by the operation of a crystallographic twofold rotation axis, and half a highly disordered chloro­form mol­ecule. The contribution to the diffraction pattern of the latter was removed using the program SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]; the unit-cell characteristics take into account the presence of CHCl₃. The dihedral angles between the planes of the naphthalene ring system and the meth­oxy­benzene rings are 71.05 (7) (syn to the central C=O group) and 57.27 (6)° (anti to the central C=O group). In the crystal, mol­ecules are linked by C—H⋯O inter­actions, generating C(12) chains running parallel to the b axis.

Afro Middle East Asian symposium on cancer cooperation

This manuscript captures the discussion and recommendations that came out of a special Afro Asian symposium involving 13 countries. Unmet needs and cost-effective solutions with special emphasis on training form the backbone of practical next steps.

2-(4,5-Dimeth-oxy-2-nitro-phen-yl)-4-meth-oxy-9-phenyl-sulfonyl-9H-carbazole-3-carbaldehyde

In the title compound, C₂₈H₂₂N₂O₈S, the carbazole ring system is roughly planar, with a maximum deviation of 0.084 (3) Å for the C atom connected to the 4,5-dimeth­oxy-2-nitro­phenyl ring. The dihedral angle between the carbazole system and the dimeth­oxy-substituted nitro­phenyl ring is 57.05 (10)°. The aldehyde C atom deviates by 0.164 (5) Å from its attached carbazole ring system. The mol­ecular structure is stabilized by C—H⋯O inter­actions which generate two S(6) and one S(7) ring motif. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming R₃³(15) ring motifs, which are further crosslinked by R₃²(19) ring motifs, resulting in (002) layers. The crystal packing also features C—H⋯π inter­actions.

Methyl 3′-(2,5-dimethylbenzyl)-1′-methyl-2-oxo-4′-phenylspiro[indoline-3,2′-pyrrolidine]-3′-carboxylate chloroform monosolvate

In the title solvate, C₂₉H₃₀N₂O₃·CHCl₃, the dihedral angle between the indole ring system (r.m.s. deviation = 0.050 Å) and the 4-methyl­pyrrolidine ring is 88.88 (8)°. The latter ring adopts an envelope conformation with the N atom as the flap. Its mean plane makes dihedral angles of 86.94 (11) and 42.08 (9)° with the phenyl and di­methyl­benzene rings, respectively. The mol­ecular conformation is stabilized by intra­molecular C—H⋯O hydrogen bonds, which generate S(6) and S(9) ring motifs. The chloro­form solvent mol­ecule is linked to the organic mol­ecule by a C—H⋯O hydrogen bond involving the carbonyl O atom of the carboxyl­ate group. In the crystal, mol­ecules are linked via bifurcated N—H⋯(N,O) and C—H⋯O hydrogen bonds, forming chains propagating along [001].

Methyl 3′-benzyl-4′-(2,4-dichlorophenyl)-1′-methyl-2-oxospiro[indoline-3,2′-pyrrolidine]-3′-carboxylate

In the title compound, C₂₇H₂₄Cl₂N₂O₃, the indole ring system is essentially planar, with a maximum deviation of 0.082 (2) Å for the carbonyl C atom. It makes a dihedral angle of 88.53 (6)° with the mean plane of the 4-methyl­pyrrolidine ring, which adopts an envelope conformation with the N atom at the flap position. The mol­ecular structure is stabilized by intra­molecular C—H⋯O hydrogen bonds, which generate S(6) and S(7) ring motifs, and an intra­molecular π–π inter­action involving the benzyl and di­chloro-substituted benzene rings [centroid–centroid distance = 3.6291 (11) Å]. In the crystal, mol­ecules are linked via N—H⋯O hydrogen bonds, forming C(7) chains running parallel to [10-1].

2-(4,5-Dimethoxy-2-nitrophenyl)-4-methoxy-3-methyl-9-phenylsulfonyl-9H-carbazole

In the title compound, C₂₈H₂₄N₂O₇S, the carbazole system is essentially planar, with a maximum deviation of 0.0644 (19) Å for the C atom connected to the 4,5-dimeth­oxy-2-nitro­phenyl group. The dihedral angle between the carbazole moiety and the dimethoxy-substituted nitrophenyl ring is 58.55 (7)°. The sulfonyl group forms two intra­molecular C—H⋯O bonds with the adjacent carbazole system, forming two cyclic S(6) motifs. In the crystal, mol­ecules are linked along the a axis in bands consisting of cyclic R₃³(15) motifs through two further C—H⋯O hydrogen bonds.

2-(4,5-Di-chloro-2-nitro-phen-yl)-4-meth-oxy-3-methyl-9-phenyl-sulfon-yl-9H-carbazole

In the title compound, C₂₆H₁₈Cl₂N₂O₅S, the carbazole ring system is essentially planar with a maximum deviation of 0.0498 (16) Å for the N atom. The carbazole ring system is almost orthogonal to the phenyl­sulfonyl and di­chloro-substituted nitro­phenyl rings, making dihedral angles of 84.23 (7) and 85.46 (12)°, respectively. The mol­ecular structure features intra­molecular C—H⋯O inter­actions, which generate two S(6) ring motifs. In the crystal, mol­ecules are linked by C—Cl⋯O halogen bonds [3.016 (3) Å, 166.63 (5)°], which generate infinite C(8) chains running parallel to [010].

2-(4-Chloro-2-nitrophenyl)-4-methoxy-9-phenylsulfonyl-9H-carbazole-3-carbaldehyde

In the sterically hindered title compound, C₂₆H₁₇ClN₂O₆S, the carbazole ring has a maximum deviation from planarity of 0.067 (4) Å for the C atom connected to the aldehyde group. The carbazole moiety forms a dihedral angle of 72.8 (1)° with the nitro-substituted benzene ring. The O atom of the meth­oxy group deviates by 0.186 (1) Å from the adjacent carbazole moiety. The phenyl­sulfonyl group forms intra­molecular C—H⋯O bonds between sulfone O atoms and the carbazole moiety, resulting in two S(6) rings. In the crystal, the nitrated benzene rings are linked via C—H⋯O inter­actions forming infinite C(7) chains along [100]. The crystal packing is also characterized by C—H⋯π inter­actions, which result in inversion dimers.

Association between proinflammatory cytokines and lipid peroxidation in patients with severe dengue disease around defervescence

OBJECTIVES

Proinflammatory cytokines and the oxidative stress response are reported to be involved in dengue viral disease. The present study investigated the correlation of proinflammatory cytokines and lipid peroxidation with dengue severity.

METHODS

Clinical samples from 27 dengue fever (DF) cases, 30 dengue haemorrhagic fever (DHF) cases, and 24 dengue shock syndrome (DSS) cases were studied around defervescence, along with samples from 30 healthy controls. Plasma samples were analysed for tumour necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) by ELISA and for malondialdehyde (MDA) by thiobarbituric acid assay.

RESULTS

Dengue-infected individuals had significantly higher levels of TNF-α, IFN-γ, and MDA in comparison to controls. The ratio of TNF-α to IFN-γ was significantly higher in DHF and DSS than in DF. A TNF-α/IFN-γ ratio value of 5.69 around defervescence predicted DHF and DSS with moderate accuracy and thus may serve as an indicator to study dengue severity. The study observed a significant positive correlation of lipid peroxides with TNF-α levels and the TNF-α/IFN-γ ratio in severe dengue cases.

CONCLUSIONS

We propose that the oxidative stress response induced by the dengue virus may trigger the inflammatory cytokine responses in dengue severity and thereby contributes to the pathogenesis of the disease; however the interplay between the oxidative response and inflammatory activity in disease virulence needs further study.

Human plasma cells express granzyme B

While studying the plasma cell (PC) compartment in human tonsils, we identified that immunoglobulin kappa or lambda chain-expressing PCs are the main cells expressing granzyme B (GrzB). In vitro studies revealed that activated B cells differentiated into GrzB-expressing PCs when co-cultured with macrophages and follicular helper T cells. This effect could be reproduced on combined stimulation of IL-15 (produced by macrophages) and IL-21 (produced by T follicular helper cells) in a STAT3-dependent manner. Whereas IL-21 triggers the transcription of mRNA of GrzB, IL-15 synergizes the translation of GrzB proteins. The precise role of GrzB in PC biology remains to be understood and studies in mice will not help as their PCs do not express GrzB.

rac-4-(4-Chloro-phen-yl)-2-methyl-amino-3-nitro-5,6,7,8-tetra-hydro-4H-chromen-5-one

The title compound, C16H15ClN2O4, contains a chiral centre and crystallizes as a racemate. The methyl-ene group β-positioned to the carbonyl group is partially (21%) disordered. It flips to the opposite sides of the corresponding six-membered carbocycle by -0.304 (3) and 0.197 (11) Å, producing alternative envelope conformations. The planes of the pyran and chloro-phenyl rings form a dihedral angle of 86.25 (9)°. The mol-ecular structure is characterized by an intra-molecular N-H⋯O inter-action, which generates an S(6) ring motif. The corresponding amino N atom deviates from the plane of the pyran ring by 0.1634 (19) Å. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming C(8) chains running parallel to the b-axis direction. The crystal structure also features C-H⋯π inter-actions.

(4S*)-2-Methyl-amino-3-nitro-4-(4-nitro-phen-yl)-5,6,7,8-tetra-hydro-4H-chromen-5-one

The title compound, C16H15N3O6, is asymmetric with a chiral centre located in the pyran ring and crystallizes as a racemate. The six-membered carbocyclic ring adopts an envelope conformation with the central CH2 C atom as the flap. The amine N atom deviates from the mean plane of the pyran ring by 0.1365 (15) Å. The nitro-phenyl ring is almost orthogonal to the pyran ring and the mean plane of the six-membered carbocyclic ring, the dihedral angle between their mean planes being 88.30 (7) and 87.61 (8)°, respectively. The mol-ecular structure is stabilized by an intra-molecular N-H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming infinite bands lying parallel to (-110) and composed of alternate R 2 (2)(24) and R 2 (4)(12) graph-set ring motifs. The crystal structure is further stabilized by C-H⋯π inter-actions, forming a three-dimensional structure.

4-(4-Bromo-phen-yl)-2-methyl-amino-3-nitro-5,6,7,8-tetra-hydro-4H-chromen-5-one

In the title compound, C₁₆H₁₅BrN₂O₄, the six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation with the disordered methyl­ene C atom as the flap. The pyran ring is almost orthogonal to the chloro­phenyl ring, making a dihedral angle of 87.11 (12)°. The amine-group N atom deviates significantly from the pyran ring [0.238 (3) Å]. The mol­ecular structure is stabilized by an intra­molecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, which generate C(8) chains running parallel to the b axis. The chains are linked by C—H⋯π inter­actions. The methyl­ene-group C atom of the chromene system that is disordered, along with its attached H atoms and the H atoms on the two adjacent C atoms, has an occupancy ratio of 0.791 (7):0.209 (7).

Rapid plasticity of motor corticospinal system with robotic reach training

Goal-directed reaching is important for the activities of daily living. Populations of neurons in the primary motor cortex that project to spinal motor circuits are known to represent the kinematics of reaching movements. We investigated whether repetitive practice of goal-directed reaching movements induces use-dependent plasticity of those kinematic characteristics, in a manner similar to finger movements, as had been shown previously. Transcranial magnetic stimulation (TMS) was used to evoke upper extremity movements while the forearm was resting in a robotic cradle. Plasticity was measured by the change in kinematics of these evoked movements following goal-directed reaching practice. Baseline direction of TMS-evoked arm movements was determined for each subject. Subjects then practiced three blocks of 160 goal-directed reaching movements in a direction opposite to the baseline direction (14 cm reach 180° from baseline direction) against a 75-Nm spring field. Changes in TMS-evoked whole arm movements were assessed after each practice block and after 5 min following the end of practice. Direction and the position of the point of peak velocity of TMS-evoked movements were significantly altered following training and at a 5-min interval following training, while amplitude did not show significant changes. This was accompanied by changes in the motor-evoked potentials (MEPs) of the shoulder and elbow agonist muscles that partly explained the change in direction, mainly by increase in agonist MEP, without significant changes in antagonists. These findings demonstrate that the arm representation accessible by motor cortical stimulation under goes rapid plasticity induced by goal-directed robotic reach training in healthy subjects.

A rare case of small bowel obstruction secondary to ovarian torsion in an IVF pregnancy

A 39- year-old woman, who conceived following in vitro fertilisation (IVF) treatment, presented at 12 weeks gestation with symptoms of ovarian hyperstimulation syndrome (OHSS), abdominal pain, vomiting and diarrhoea. Subsequent investigations found small bowel obstruction  secondary to ovarian torsion. Surgical management to remove a necrotic ovary and fallopian tube led to a good recovery from the acute illness. A postoperative ultrasound scan confirmed a viable pregnancy and the patient was discharged. Her case demonstrates a rare complication of OHSS and ovarian torsion leading to small bowel obstruction.