Pre-Flight Calibration of the Mars 2020 Rover Mastcam Zoom (Mastcam-Z) Multispectral, Stereoscopic Imager

The NASA Perseverance rover Mast Camera Zoom (Mastcam-Z) system is a pair of zoomable, focusable, multi-spectral, and color charge-coupled device (CCD) cameras mounted on top of a 1.7 m Remote Sensing Mast, along with associated electronics and two calibration targets. The cameras contain identical optical assemblies that can range in focal length from 26 mm ( 25.5 ∘ × 19.1 ∘ FOV ) to 110 mm ( 6.2 ∘ × 4.2 ∘ FOV ) and will acquire data at pixel scales of 148-540 μm at a range of 2 m and 7.4-27 cm at 1 km. The cameras are mounted on the rover's mast with a stereo baseline of 24.3 ± 0.1  cm and a toe-in angle of 1.17 ± 0.03 ∘ (per camera). Each camera uses a Kodak KAI-2020 CCD with 1600 × 1200 active pixels and an 8 position filter wheel that contains an IR-cutoff filter for color imaging through the detectors' Bayer-pattern filters, a neutral density (ND) solar filter for imaging the sun, and 6 narrow-band geology filters (16 total filters). An associated Digital Electronics Assembly provides command data interfaces to the rover, 11-to-8 bit companding, and JPEG compression capabilities. Herein, we describe pre-flight calibration of the Mastcam-Z instrument and characterize its radiometric and geometric behavior. Between April 26 t h and May 9 t h , 2019, ∼45,000 images were acquired during stand-alone calibration at Malin Space Science Systems (MSSS) in San Diego, CA. Additional data were acquired during Assembly Test and Launch Operations (ATLO) at the Jet Propulsion Laboratory and Kennedy Space Center. Results of the radiometric calibration validate a 5% absolute radiometric accuracy when using camera state parameters investigated during testing. When observing using camera state parameters not interrogated during calibration (e.g., non-canonical zoom positions), we conservatively estimate the absolute uncertainty to be < 10 % . Image quality, measured via the amplitude of the Modulation Transfer Function (MTF) at Nyquist sampling (0.35 line pairs per pixel), shows MTF Nyquist = 0.26 - 0.50 across all zoom, focus, and filter positions, exceeding the > 0.2 design requirement. We discuss lessons learned from calibration and suggest tactical strategies that will optimize the quality of science data acquired during operation at Mars. While most results matched expectations, some surprises were discovered, such as a strong wavelength and temperature dependence on the radiometric coefficients and a scene-dependent dynamic component to the zero-exposure bias frames. Calibration results and derived accuracies were validated using a Geoboard target consisting of well-characterized geologic samples.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11214-021-00795-x.

Multi-model Meteorological and Aeolian Predictions for Mars 2020 and the Jezero Crater Region

Nine simulations are used to predict the meteorology and aeolian activity of the Mars 2020 landing site region. Predicted seasonal variations of pressure and surface and atmospheric temperature generally agree. Minimum and maximum pressure is predicted at Ls ∼ 145 ∘ and 250 ∘ , respectively. Maximum and minimum surface and atmospheric temperature are predicted at Ls ∼ 180 ∘ and 270 ∘ , respectively; i.e., are warmest at northern fall equinox not summer solstice. Daily pressure cycles vary more between simulations, possibly due to differences in atmospheric dust distributions. Jezero crater sits inside and close to the NW rim of the huge Isidis basin, whose daytime upslope (∼east-southeasterly) and nighttime downslope (∼northwesterly) winds are predicted to dominate except around summer solstice, when the global circulation produces more southerly wind directions. Wind predictions vary hugely, with annual maximum speeds varying from 11 to 19 ms - 1 and daily mean wind speeds peaking in the first half of summer for most simulations but in the second half of the year for two. Most simulations predict net annual sand transport toward the WNW, which is generally consistent with aeolian observations, and peak sand fluxes in the first half of summer, with the weakest fluxes around winter solstice due to opposition between the global circulation and daytime upslope winds. However, one simulation predicts transport toward the NW, while another predicts fluxes peaking later and transport toward the WSW. Vortex activity is predicted to peak in summer and dip around winter solstice, and to be greater than at InSight and much greater than in Gale crater.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11214-020-00788-2.

The Mars 2020 Perseverance Rover Mast Camera Zoom (Mastcam-Z) Multispectral, Stereoscopic Imaging Investigation

Mastcam-Z is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission's Perseverance rover. Mastcam-Z consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000 nm color imaging with fields of view from 25.6° × 19.2° (26 mm focal length at 283 μrad/pixel) to 6.2° × 4.6° (110 mm focal length at 67.4 μrad/pixel). The cameras can resolve (≥ 5 pixels) ∼0.7 mm features at 2 m and ∼3.3 cm features at 100 m distance. Mastcam-Z shares significant heritage with the Mastcam instruments on the Mars Science Laboratory Curiosity rover. Each Mastcam-Z camera consists of zoom, focus, and filter wheel mechanisms and a 1648 × 1214 pixel charge-coupled device detector and electronics. The two Mastcam-Z cameras are mounted with a 24.4 cm stereo baseline and 2.3° total toe-in on a camera plate ∼2 m above the surface on the rover's Remote Sensing Mast, which provides azimuth and elevation actuation. A separate digital electronics assembly inside the rover provides power, data processing and storage, and the interface to the rover computer. Primary and secondary Mastcam-Z calibration targets mounted on the rover top deck enable tactical reflectance calibration. Mastcam-Z multispectral, stereo, and panoramic images will be used to provide detailed morphology, topography, and geologic context along the rover's traverse; constrain mineralogic, photometric, and physical properties of surface materials; monitor and characterize atmospheric and astronomical phenomena; and document the rover's sample extraction and caching locations. Mastcam-Z images will also provide key engineering information to support sample selection and other rover driving and tool/instrument operations decisions.

Large-scale discovery of male reproductive tract-specific genes through analysis of RNA-seq datasets

Background

The development of a safe, effective, reversible, non-hormonal contraceptive method for men has been an ongoing effort for the past few decades. However, despite significant progress on elucidating the function of key proteins involved in reproduction, understanding male reproductive physiology is limited by incomplete information on the genes expressed in reproductive tissues, and no contraceptive targets have so far reached clinical trials. To advance product development, further identification of novel reproductive tract-specific genes leading to potentially druggable protein targets is imperative.

Results

In this study, we expand on previous single tissue, single species studies by integrating analysis of publicly available human and mouse RNA-seq datasets whose initial published purpose was not focused on identifying male reproductive tract-specific targets. We also incorporate analysis of additional newly acquired human and mouse testis and epididymis samples to increase the number of targets identified. We detected a combined total of 1178 genes for which no previous evidence of male reproductive tract-specific expression was annotated, many of which are potentially druggable targets. Through RT-PCR, we confirmed the reproductive tract-specific expression of 51 novel orthologous human and mouse genes without a reported mouse model. Of these, we ablated four epididymis-specific genes (Spint3, Spint4, Spint5, and Ces5a) and two testis-specific genes (Pp2d1 and Saxo1) in individual or double knockout mice generated through the CRISPR/Cas9 system. Our results validate a functional requirement for Spint4/5 and Ces5a in male mouse fertility, while demonstrating that Spint3, Pp2d1, and Saxo1 are each individually dispensable for male mouse fertility.

Conclusions

Our work provides a plethora of novel testis- and epididymis-specific genes and elucidates the functional requirement of several of these genes, which is essential towards understanding the etiology of male infertility and the development of male contraceptives.

Abstract 1963: Targeting hematological malignancies with two functionally and mechanistically distinct classes of cereblon mediated protein homeostatic modulators

BioTheryX's novel and unique Protein Homeostatic Modulators (PHMsTM) are small molecule “molecular glues” that promote ubiquitination of substrate proteins by the CRL4CRBN (CUL4-DDB1-RBX1-CRBN) ubiquitin ligase, leading to their subsequent degradation by the 26S proteasome. The therapeutic benefit of targeted protein degradation via cereblon (CRBN) has been clinically validated by the immunomodulatory drugs lenalidomide and pomalidomide in 5q-deletion-associated myelodysplastic syndrome and multiple myeloma, respectively. We present PHM® therapeutic candidates with novel targeted degradation profiles of disease-relevant proteins including GSPT1, Ikaros, and CK1α via CRBN with significant clinical potential in the treatment of hematological malignancies as well as solid tumors.

Phenotypic screens of our proprietary PHM® library has led to the discovery of compounds that exhibit significant cytotoxicity in human AML and lymphoma cell lines, unlike classical IMiDs such as lenalidomide and pomalidomide. Cell viability assays revealed that these PHMsTM have IC50s in the low-nanomolar range. Importantly, they exhibit a large in vitro safety window with higher IC50s in normal human liver epithelial cells. The compounds are highly potent and can achieve significant AML and lymphoma selective cytotoxicity with short-term exposure of only 8 hours suggesting a highly rapid mechanism of action. Immunoblot analysis shows that the PHMsTM degrade CRBN substrates such as GSPT1, Ikaros and CK-1α and concomitantly activate the apoptosis machinery within 6 hours of treatment. The substrate degradation profile of PHMsTM combined with the cytokine profile divides the PHMsTM into two distinct mechanistic and functional classes of molecules - (1) purely cytotoxic, and (2) cytotoxic and immune-modulatory PHMsTM. Human PBMCs activated with lipopolysaccharide or α-CD3 followed by DMSO or compound treatment for 24 hours revealed that PHMsTM belonging to the latter class inhibit proinflammatory cytokines such as IL-1β, IL-6 and TNF-α as well as induce IL-2, an indicator of T cell activation, and are a 100-fold more potent than pomalidomide.

In vivo efficacy of BTX-PHMsTM was evaluated using the MV-4-11 human AML xenograft model in athymic nude mice. The study shows a significant reduction in tumor volume with daily dosing, further establishing the PHMsTM as clinical candidates for AML. Of significance, is the effect of BTX1188 that completely obliterates the tumors within 30 days of dosing and maintains tumor free animals until the end of the study. The effective short-term exposure in vitro is also reflected in vivo where intermittent dosing with the PHM results in significant reduction in tumor volume. Finally, BTX-PHMsTM exhibit significant oral bioavailability, thus making them promising clinical candidates for treatment of hematological malignancies as well as early discovery candidates for solid tumors.

Citation Format: Aparajita Hoskote Chourasia, Leah Fung, Angela Pasis, Brooke McElwee, Angela Schoolmeesters, Normand Richard, Imelda Lam, Eduardo Torres, Paul Erdman, Robert Sullivan, David Hecht, Kyle W. Chan, Frank Mercurio, David I. Stirling. Targeting hematological malignancies with two functionally and mechanistically distinct classes of cereblon mediated protein homeostatic modulators [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1963.

The novel protein homeostatic modulator BTX306 is active in myeloma and overcomes bortezomib and lenalidomide resistance

Small molecules targeting the cereblon-containing E3 ubiquitin ligase including thalidomide, lenalidomide, and pomalidomide modulate turnover of downstream client proteins and demonstrate pre-clinical and clinical anti-myeloma activity. Different drugs that engage with cereblon hold the potential of unique phenotypic effects, and we therefore studied the novel protein homeostatic modulator (PHM™) BTX306 with a unique thiophene-fused scaffold bearing a substituted phenylurea and glutarimide. This agent much more potently reduced human-derived myeloma cell line viability, with median inhibitory concentrations in the single nanomolar range versus micromolar values for lenalidomide or pomalidomide, and more potently activated caspases 3/8/9. While lenalidomide and pomalidomide induced greater degradation of Ikaros and Aiolos in myeloma cells, BTX306 more potently reduced levels of GSPT1, eRF1, CK1α, MCL-1, and c-MYC. Suppression of cereblon or overexpression of Aiolos or Ikaros induced relative resistance to BTX306, and this agent did not impact viability of murine hematopoietic cells in an in vivo model, demonstrating its specificity for human cereblon. Interestingly, BTX306 did show some reduced activity in lenalidomide-resistant cell line models but nonetheless retained its nanomolar potency in vitro, overcame bortezomib resistance, and was equipotent against otherwise isogenic cell line models with either wild-type or knockout TP53. Finally, BTX306 demonstrated strong activity against primary CD138-positive plasma cells, showed enhanced anti-proliferative activity in combination with bortezomib and dexamethasone, and was effective in an in vivo systemic model of multiple myeloma. Taken together, the data support further translational studies of BTX306 and its derivatives to the clinic for patients with relapsed and/or refractory myeloma. KEY MESSAGES: BTX306 has a unique thiophene-fused scaffold bearing phenylurea and glutarimide. BTX306 is more potent against myeloma cells than lenalidomide or pomalidomide. BTX306 overcomes myeloma cell resistance to lenalidomide or bortezomib in vitro. BTX306 is active against primary myeloma cells, and shows efficacy in vivo.

Understanding the structure of a country’s health service providers for defence health engagement

There are a variety of structural and systems frameworks for describing the building blocks of country’s public health and health systems. In this paper, we propose a conceptual framework for a holistic view of a country’s health service providers in order to inform the plan for Defence Health Engagement activities with partner countries. This includes all potential government ministries involved in healthcare provision, the independent, private sector and the non-government organisation/charity sector. The framework provides a visualisation to support the analysis of a country’s health services providers. We propose that recognising and analysing the different contributions of all these national health providers is essential for understanding the wider political economy of a nation’s health systems. This can inform a plan of Defence Health Engagement for capacity building in crisis response, development and health systems strengthening.

Differential effects of the 1,25D3-MARRS receptor (ERp57/PDIA3) on murine mammary gland development depend on the vitamin D3 dose

1,25 dihydroxyvitamin D3 (1,25D3) is the most potent biologically active form of vitamin D3. Its actions on the mammary gland include cell growth inhibition and anti-cancer effects. This study's purpose was to explore the role of the 1,25D3-membrane associated rapid response steroid (MARRS) receptor in the mammary gland using a tissue-specific knockout mouse model and a vitamin D3 dietary intervention. Three genotype groups were created using the Cre/loxp system to knock-down (+/-) and knockout (-/-) the MARRS receptor in epithelial cells of mammary glands (MG). Abdominal MGs were collected from 6-week old female mice (n = 94) on diets of 10,000 IU/kg (excess), 1,000 IU/kg (sufficient) or 0 IU/kg (deficient) of D3. There was a significant interaction between genotype and diet regarding number of terminal end buds (TEBs) (p = 0.001) and ductal coverage of the fat pad (p = 0.03). MARRS -/- mice on the sufficient diet had significantly fewer TEBs (p = 0.001) compared to MARRS +/+ on the same diet, but the opposite effect was seen in mice on the excess diet. There were no effects of genotype on TEBs when animals were vitamin D3 deficient. These results suggest that there is an effect of MARRS on mammary gland development that is dependent on 25(OH)D status, specifically, altering the number of highly proliferative TEBs. Increased numbers of TEBs have been correlated with increased breast cancer risk later in life. Therefore the results of this study warrant further examination of 25(OH)D status and recommendations in adolescent humans to reduce dietary effects on future breast cancer risk.

Differential gene expression profiles of human efferent ducts and proximal epididymis

BACKGROUND

Gene expression patterns along the epididymis are established by specific transcription factor networks that coordinate region-specific functions. In rodents, the epididymis can be divided in up to 19 segments. Based on gross anatomy, the human epididymis is divided into caput, corpus, and cauda segments together with efferent ducts that occupy the proximal part of this organ.

OBJECTIVES

To determine to which extent gene expression pattern is segmented along the efferent ducts and the proximal region of the epididymis in men of reproductive age.

MATERIALS AND METHODS

Epididymal transcriptome profiling was performed on eight distinct regions from three donors. Microarray analysis was performed on a gene-chip microarray. Differentially expressed genes (DEGs)>2-fold change (P < .05) were clustered in relation to their intensity profiles. Overrepresented biological functions from gene ontology were searched using DAVID 6.8. Expression profiles were validated by qRT-PCR quantification of selected genes.

RESULTS

There were no DEGs among segments 1-3 of efferent ducts region neither among segments 4-6 of the caput epididymis. 1058 DEGs were identified between efferent ducts and the epididymis, whereas 444 and 846 DEGs distinguished the caput from the corpus (section 7) and cauda (section 8) epididymis, respectively. A total of 131 DEGs were detected between corpus (7) and cauda (8) transcriptomes. Up-regulated DEGs in the efferent ducts were predominantly related to cilium assembly/movement and cell differentiation. Fertilization, defense, and immune responses were associated with caput epididymis (4-6), while spermatogenesis and protein binding were found all along the epididymis (4-8).

DISCUSSION

The proximal human epididymis is exclusively occupied by efferent ducts with a distinct DEG profile compared with the downstream epididymal segments. Moreover, gene expression profiling revealed two regions in the human epididymis: the caput and the distal corpus/cauda region.

CONCLUSIONS

Human epididymal transcriptome reveals limited DEGs, and efferent ducts have a distinct DEGs profile.

Pathologic fracture healing after femoral limb salvage in a dog

BACKGROUND

Bone sarcomas are a significant cause of pain, disability, and mortality in dogs. A variety of surgical limb salvage options are available to preserve limb function with comparable prognosis to amputation.

CASE REPORT

This report describes successful healing after plate fixation of an undifferentiated sarcoma pathologic femoral fracture in a dog. The fracture was treated surgically with curettage of the tumour site, placement of autogenous bone graft, and then stabilized using a locking plate rod construct. The patient regained excellent mobility after surgery and was managed with monthly pamidronate therapy. Serial radiographs demonstrate progressive healing of the pathologic fracture. Ultimately, the patient developed a maxillary fibrosarcoma and was euthanased 1 year after treatment of the femoral fracture. Postmortem histopathological evaluation of the pathologic fracture site demonstrated complete bone healing.

CONCLUSION

This case highlights the possibilities of limb salvage by fracture stabilization and bone healing as a viable option in select patients.

Policy Recommendations to Address Financial Toxicity Following Cancer in Low- and Middle-Income Countries: One Size Does Not Fit All

Background: Evidence to guide cancer policy-making is scarce in low- and middle-income countries (LMIC). Furthermore, most economic studies in cancer have been conducted from the provider's or payer's perspective. Aim: The ASEAN Costs in Oncology Study (ACTION) was conducted to provide the essential intelligence for national policymakers and official development assistance donors to construct economically sound national cancer control plans. Methods: In the ACTION study, 9513 newly diagnosed cancer patients from eight LMIC in southeast Asia were prospectively followed-up for adverse economic outcomes up to one year after diagnosis, through serial interviews and use of cost diaries. Results: Country-specific analysis of the ACTION Study data had revealed that just within a year of diagnosis, 1 in 2 Malaysian cancer survivors had reported spending more than 30% of their annual household income for cancer related expenditures (FC: financial catastrophe). Strikingly, Malaysia, albeit being a higher income nation, appeared to have fared worse than Thailand, where only 1 in 3 cancer survivors reported FC. Nonetheless, in contrast to finding of the regional study that medical payments (drugs, hospitalization, consultation), largely explained the incidence of FC following cancer, only half of the reported catastrophic expenditures in Malaysia were attributed to medical expenditures suggesting that nonmedical payments related to cancer (e.g., travel, accommodation, childcare) was an important contributor to adverse financial outcomes. Furthermore, marked institutional variations in levels of catastrophic expenditures were observed in Malaysia, even within the public healthcare system. Proportion of patients experiencing FC in the general government hospitals was only 33% compared with 65% in the public academic hospitals. Although late stage at cancer diagnosis largely explained the increased risk of adverse economic outcomes and death, patients from low-income households remained vulnerable even when diagnosed with earlier stages. Conclusion: The findings of the ACTION Study importantly highlight the need for LMIC to undertake their own studies examining the financial impact of cancer in the population, to take affirmative actions to reduce financial loss and premature deaths associated with cancer. From the Malaysian perspective, there appears to be an urgent need to improve social support for cancer in the country, be it through government-led programs such as disability insurance and short term credit or multisectoral collaboration with civil societies, private industries, and philanthropic organizations. Key policy changes should also include prioritization of programs which would allow early detection of cancer, re-examination of the national health financing system to ensure that public funds are channeled to those who need them the most, and addressing disparities in funding between public hospitals.

The Influence of Social Determinants of Health on Primary and Secondary Cancer Prevention Health Seeking Behaviors Among Refugees in Middle East and North Africa Host Countries

Background: The National Cancer Institute (NCI) recognizes 'cancer health disparities' as adverse differences in cancer incidence, mortality, and burden that exist among specific population groups. Refugee populations often lack access to primary care and health screening or preventive services, leading to late diagnosis, and higher cancer burdens of cancer-related outcomes and mortality. The disproportionate burden of cancer in refugee populations, necessitates research on specific determinants and disparities influencing their cancer care. Ongoing conflicts across the Middle East and North Africa (MENA) region have caused an unprecedented displacement of individuals to host countries. Four countries in the region, Jordan, Lebanon, Palestinian territories, and Turkey, host more than an estimated 3 million refugees collectively. As the region experiences a shift in disease burden to noncommunicable diseases, the health systems of these host countries are placed under increased pressure to manage chronic conditions of refugees, such as cancer. These large-scale displacements in the MENA region present a unique opportunity to better understand the drivers of health disparities with the aim of improving cancer health in refugee populations. Aim: Through application of a Social Determinants of Health (SDOH) framework, this study aims to understand the landscape of health seeking behaviors for cancer prevention among refugees in Jordan, Lebanon, Palestinian territories, and Turkey. This is a first step to inform future research and initiatives around refugee cancer services. Methods: A systematic literature review was completed according to PRISMA standards, with assistance from the NIH Library. A review protocol was developed, and all literature that met eligibility criteria was included. Thematic coding and analysis was then performed to describe observational associations between cancer prevention behaviors and SDOH among refugees. Results: The results reveal patterns in which SDOH directly and indirectly influence the landscape of refugee health seeking behaviors for cancer prevention services in their host countries. The SDOH that most clearly influenced cancer prevention behaviors include health system capacity, navigating host country's health system, delivery of cancer prevention services, acculturation, competing social, health, and financial priorities, and the built environment. These interrelated constructs impact refugees' ability to access and participate in cancer prevention services, as both enabling and inhibit factors. Conclusion: The influence of SDOH on seeking cancer care are important for refugee populations around the world since they are faced with comparable contextual factors that both enable and inhibit health seeking behaviors. Understanding the interplay between the SDOH constructs is pivotal toward developing targeted interventions by host countries to improve cancer prevention behaviors and health outcomes among refugees.

Medical oncology workload in Canada: infrastructure, supports, and delivery of clinical care

Background

In 2000, a Canadian task force recommended that medical oncologists (mos) meet a target of 160-175 new patient consultations per year. Here, we report the Canadian results of a global survey of mo workload compared with mo workload in other high-income countries (hics).

Methods

Using a snowball method, an online survey was distributed by national oncology societies to chemotherapy-prescribing physicians in 22 hics (World Bank criteria). The survey was distributed within Canada to all members of the Canadian Association of Medical Oncologists. Workload was measured as the annual number of new cancer patient consults per oncologist.

Results

The survey was completed by 782 oncologists from hics, including 58 from Canada. Median annual consults per mo were 175 in Canada compared with 125 in other hics. The proportions of mos having 100 or fewer consults or more than 300 consults per year were 3% (2/58) and 5% (3/58) in Canada compared with 31% (222/724) and 16% (116/724) in other hics (p < 0.001 and p = 0.023 respectively). The median number of patients seen in a full-day clinic was 15 in Canada and 25 in other hics (p = 0.220). Canadian mos reported spending a median of 55 minutes per new consultation; new consultations of 35 minutes were reported in other hics (p < 0.001). Median hours worked per week was 55 in Canada and 45 in other hics (p = 0.200).

Conclusions

Although the median annual clinical volume for Canadian mos aligns with recommended targets, half the respondents exceeded that level of activity. Health policymakers and educators have to consider mo workforce supply and alternative models of care in preparation for the anticipated surge in cancer incidence in the coming decade.

Randomized clinical trial of elective resection versus observation in diverticulitis with extraluminal air or abscess initially managed conservatively

Background

The aim of this RCT was to determine whether elective resection following successful non-operative management of a first episode of acute sigmoid diverticulitis complicated by extraluminal air with or without abscess is superior to observation in terms of recurrence rates.

Methods

This was a single-centre, sequential design RCT. Patients were randomized to elective surgery or observation following non-operative management and colonoscopy. Non-operative management included nil by mouth, intravenous fluids, intravenous antibiotics, CT with intravenous contrast on arrival at hospital, and repeat CT with intravenous and rectal contrast on day 3 in hospital. The primary endpoint was recurrent diverticulitis at 24 months. Patients with a history of sigmoid diverticulitis, immunosuppression or peritonitis were not included.

Results

Of 137 screened patients, 107 were assigned randomly to elective surgery (26) or observation (81), and underwent the allocated intervention after successful non-operative management. Conservative management failed in 15 patients. Groups were similar in age, sex, BMI, co-morbidities and colorectal POSSUM. Rates of recurrent diverticulitis differed significantly in the elective surgery and observation groups (8 versus 32 per cent; P = 0·019) at a mean(s.d.) follow-up of 37·8(8·6) and 35·2(9·2) months respectively. There was also a significant difference in time to recurrence (median 11 versus 7 months; P = 0·015). A total of 28 patients presented with recurrent diverticulitis complicated by extraluminal air and/or abscess (2 elective surgery, 26 observation), all of whom recovered with repeat non-operative management.

Conclusion

The majority of patients observed following conservative management of diverticulitis with local extraluminal air do not require elective surgery. Registration number: NCT01986686 (http://www.clinicaltrials.gov).