Recombinant outer membrane protein OmpC induces protective immunity against Aeromonashydrophila infection in Labeorohita.

Aeromonashydrophila is an opportunistic pathogen that causes enormous loss to aquaculture industry. The outer membrane proteins of Aeromonas help in bacterium-host interaction, and are considered to be potential vaccine candidates. In the present study, we evaluated immunogenicity and protective efficacy of recombinant OmpC (rOmpC) of A. hydrophila in Indian major carp, Labeorohita. The rOmpC-vaccinated fish produced specific anti-rOmpC antibodies with a significant antibody titer, and the antisera could specifically detect the rOmpC in the cell lysates of Escherichia coli expressing rOmpC and cross-react with different Aeromonas lysates, indicating the suitability of the anti-rOmpC antisera to detect Aeromonas infection. A significant increase was noted in ceruloplasmin level, myeloperoxidase and anti-protease activities in transient and temporal manner the sera of the rOmpC-immunized fish as compared to PBS-control fish. Higher agglutination- and hemolytic activity titers in the anti-rOmpC antisera indicate stimulation of innate immunity. Expression of immune-related genes comprising various acute phase proteins, cytokines and inflammatory response molecules were modulated in the head kidney of rOmpC-immunized L. rohita. While IgM, IL1ß, and TLR-22 were significantly up-regulated at early time points (3 h-72 h), the others showed a transient augmentation at both early and later time points (SOD, lysozymes C and G, NKEF-B, C3, CXCa and TNF-α) in the rOmpC-immunized L. rohita in comparison to PBS-injected controls. These data suggest that the rOmpC-induced immune response is temporally regulated to confer immunity. In vivo challenge of the rOmpC-immunized fish with A. hydrophila showed significantly greater survival when compared to PBS-injected control fish. Thus, our results highlight the immunomodulatory role of rOmpC and demonstrate its protective efficacy in L. rohita, along with the use of anti-rOmpC antisera in detecting Aeromonas infections.

Toxin-antitoxin systems and their medical applications: current status and future perspective.

Almost all bacteria synthesize two types of toxins-one for its survival by regulating different cellular processes and another as a strategy to interact with host cells for pathogenesis. Usually, "bacterial toxins" are contemplated as virulence factors that harm the host organism. However, toxins produced by bacteria, as a survival strategy against the host, also hamper its cellular processes. To overcome this, the bacteria have evolved with the production of a molecule, referred to as antitoxin, to negate the deleterious effect of the toxin against itself. The toxin and antitoxins are encoded by a two-component toxin-antitoxin (TA) system. The antitoxin, a protein or RNA, sequesters the toxins of the TA system for neutralization within the bacterial cell. In this review, we have described different TA systems of bacteria and their potential medical and biotechnological applications. It is of interest to note that while bacterial toxin-antitoxin systems have been well studied, the TA system in unicellular eukaryotes, though predicted by the investigators, have never been paid the desired attention. In the present review, we have also touched upon the TA system of eukaryotes identified to date. KEY POINTS: Bacterial toxins harm the host and also affect the bacterial cellular processes. The antitoxin produced by bacteria protect it from the toxin's harmful effects. The toxin-antitoxin systems can be targeted for various medical applications.

Structural-functional characterization of recombinant Apolipoprotein A-I fromLabeo rohitademonstrates heat-resistant antimicrobial activity.

Apolipoprotein A-I is an anti-inflammatory, antioxidative, cardioprotective, anti-tumorigenic, and anti-diabetic in mammals. Apolipoprotein A-I also regulates innate immune defense mechanisms in vertebrates and invertebrates. Apolipoproteins A-I from mammals and several teleosts display antibacterial activities against Gram negative and Gram positive bacteria. The present study describes strategies to obtain high amounts of soluble purified recombinant Apolipoprotein A-I of Labeo rohita, an Indian major carp (rLrApoA-I). The study also reports its detailed structural and functional characterization i.e. antimicrobial activity against a number of important marine and fresh water bacterial pathogens. The rLrApoA-I was expressed in Escherichia coli BL21(DE3) pLysS expression host as a soluble protein under optimized conditions. The yield of purified rLrApoA-I was ~ 75 mg/L from soluble fraction using metal ion affinity chromatography. The authenticity of the rLrApoA-I was confirmed by MALDI-TOF-MS analysis. The secondary structure analysis showed rLrApoA-I to be predominantly alpha helical, an evolutionary conserved characteristic across mammals and teleosts. The purified rLrApoA-I exhibited antimicrobial activity as evident from inhibition of growth of a number of bacteria namely Aeromonas hydrophila, A. liquefaciens, A. culicicola, A. sobria, Vibrio harveyi, V. parahaemolyticus and Edwardsiella tarda in a dose-dependent manner. Minimum bactericidal concentration for A. liquefaciens, A. culicicola, and A. sobria, was determined to be 25 µg/ml or 0.81 µM whereas for A. hydrophila, E. tarda, V. parahaemolyticus and V. harveyi, it was determined to be 100 µg/ml or 3.23 µM. These data strongly suggest that recombinant ApoA-I from Labeo rohita could play a role in primary defense against fish pathogen. Further, at temperature ≥ 55 °C, though a loss in secondary structure was observed, no effect on its antibacterial activity was observed. This is of significance as the antibacterial activity is not likely to be lost even if the protein is subjected to high temperatures during transport.

Modulation of immune response and protective efficacy of recombinant outer-membrane protein F (rOmpF) of Aeromonas hydrophila in Labeo rohita.

The outer-membrane proteins (OMPs) of Aeromonas hydrophila, an imperative fish pathogen accountable for massive economic losses to aquaculture industry, are found to be immunogenic and considered as potential vaccine candidates. In spite of development in the formulation of vaccine candidates against Aeromonas infection, no commercial preparation has been done so far; in addition, the molecular mechanisms of immunoprotection induced by various vaccine formulations in Indian major carp, Labeo rohita, are little known. The present study was undertaken to evaluate the modulation of immunity and expression of immune-related genes post-rOmpF (recombinant outer-membrane protein of A. hydrophila, a novel vaccine candidate) immunization and protective efficacy after A. hydrophila challenge. The rOmpF-immunized fish showed a variable expression of the immune-related genes, viz. toll-like receptor 22 (TLR), complement component 3 (C3), chemokine (CXCa), tumor necrosis factor-α (TNFα), interleukin 1ß (IL-1ß), manganese superoxide dismutase (MnSOD) and natural killer enhancing factor (NKEF) in the head kidney tissues, when compared to the control group at different time intervals post-vaccination. A significant increase in serum hemolysin titer, ceruloplasmin level and myeloperoxidase activity was observed on day 140 post immunization. Also, bacterial agglutination titer and antiprotease activity were significantly increased on day 42 post immunization. No significant change was observed in lysozyme activity. Challenge studies with live A. hydrophila on day 140 post-immunization of L. rohita significantly increased the relative percentage survival (∼44%) in the vaccinated group. The results suggest that the rOmpF could be used as a potential vaccine candidate to combat A. hydrophila infection in fish.

Synthesis of peptide based epsilon toxin vaccine by covalent anchoring to tetanus toxoid.

The epsilon toxin (Etx) produced by Clostridium perfringens type B and D causes severe enterotoxaemia associated with a general edema and neurological alterations, leading to subsequent death and is listed as one of the most lethal toxins. Currently employed vaccines against C. perfringens epsilon toxin include toxoid based vaccines. Use of peptide vaccines has become an interesting approach for vaccination after the successful licensing of peptide vaccines against Haemophilus influenza, Neisseria meningitides and Streptococcus pneumonia that have demonstrated the potential and effectiveness of these vaccines. Therefore, the present study was undertaken to develop a peptide based vaccine against epsilon toxin. Peptides were selected on the basis of epitope mapping by making 35 overlapping peptides of 15 amino acid residues in length specific to the primary amino acid sequence of the toxin, with a 7 amino acid residues overlaps between sequential peptides. Chemically synthesized peptides that were recognised by the antibody against the full length epsilon toxin were further assessed for vaccine potential. The selected peptides were chemically conjugated to partially reduced tetanus toxoid (TT) using of N-succinimidyl-3(2-pyridyldithio) propionate. Immunization of BALB/c mice with TT-peptide conjugates by sub-cutaneous route induced sustained high level mixed immune response as analyzed by antibody isotyping. Immunoblot analysis and ELISA clearly indicated generation of Etx-specific antibodies. Further, neutralization studies with the antisera generated against the TT-conjugated peptide(s) demonstrated that the antisera were able to neutralize the lethal dose of epsilon toxin in vitro demonstrating its potential as a promising vaccine candidate against enterotoxaemia.

Neonatal mice with necrotizing enterocolitis-like injury develop thrombocytopenia despite increased megakaryopoiesis.

BACKGROUND: Thrombocytopenia is frequently encountered in infants with necrotizing enterocolitis (NEC). To develop a preclinical model of NEC-related thrombocytopenia, we measured serial platelet counts in 10-d-old (P10) mouse pups with trinitrobenzene sulfonic acid (TNBS)-induced NEC-like injury. We also measured platelet volume indices, immature platelet fraction (IPF), and megakaryocyte number/ploidy in these animals. METHODS: Platelet counts, platelet volume indices, and IPF were measured in control (N = 65) and TNBS-treated pups (N = 104) using an automated hematology analyzer. Bone marrow megakaryocyte number, ploidy and CD41 expression were measured by flow cytometry. These findings were confirmed in a small cohort of P3 mice with NEC-like injury. RESULTS: Murine pups with TNBS-mediated NEC-like injury developed thrombocytopenia at 15-24 h after exposure to TNBS. Intestinal injury was associated with increased platelet volume indices (mean platelet volume, platelet-to-large cell ratio, and platelet distribution width), and IPF, indicating increased thrombopoiesis. These mice also showed increased megakaryocyte number, ploidy, and CD41 expression, indicating increased megakaryocyte differentiation. CONCLUSION: Similar to human NEC, murine NEC-like injury was also associated with decreased platelet counts. There was evidence of increased megakaryocyte differentiation and thrombopoiesis, which favors peripheral consumption of platelets as the likely mechanism of thrombocytopenia in these animals, over decreased platelet production.

Clostridium perfringens beta toxin DNA prime-protein boost elicits enhanced protective immune response in mice.

Clostridium perfringens beta toxin (CPB) is the primary pathogenic factor responsible for necrotic enteritis in sheep, cattle and humans. Owing to rapid progression of the disease, vaccination is the only possible recourse to avoid high mortality in animal farms and huge economic losses. The present study reports evaluation of a cpb gene-based DNA vaccine encoding the beta toxin of C. perfringens with homologous as well as heterologous booster strategy. Immunization strategy employing heterologous booster with heat-inactivated rCPB mounted stronger immune response when compared to that generated by homologous booster. Antibody isotyping and cytokine ELISA demonstrated the immune response to be Th1-biased mixed immune response. While moderate protection of immunized BALB/c and C57BL/6 mice against rCPB challenge was observed with homologous booster strategy, heterologous booster strategy led to complete protection. Thus, beta toxin-based DNA vaccine using the heterologous prime-boosting strategy was able to generate better immune response and conferred greater degree of protection against high of dose rCPB challenge than homologous booster regimen, making it an effective vaccination approach against C. perfringens beta toxin.

Melanosomal melanin pigment in pleomorphic xanthoastrocytoma, evidence for neuronal-glial origin: A case report with review of the literature.

We describe a unique case of pleomorphic xanthoastrocytoma (PXA) in a 19-year-old male presenting with the chief complaint of seizures. On radiology, the tumor was located in the temporal lobe. It was cortically based and solid cystic in nature. Light microscopy showed pleomorphic large polygonal cells with inclusions, nuclear clustering, lipidization, and foamy cytoplasm intermingled with spindle cells arranged in sweeping pattern and focally containing cytoplasmic brownish black pigment. The pigment stained black with Fontana-Masson stain and bleached with potassium permanganate. Gomori silver stain showed reticulin fibers surrounding individual tumor cells as well as groups of cells. On immunohistochemistry, tumor cells were positive for GFAP, S-100 and focally for synaptophysin and CD34 but negative for HMB-45. CD34 revealed a specific membranous pattern around individual cells as well as groups of cells along the fibers replicating a reticulin pattern. The ultrastructural examination showed supporting melanosomes, thus confirming the melanin pigment. Sequencing for BRAF V600E showed a heterozygous mutation. To our knowledge only five cases of PXA with melanin pigment have been reported and none of which described BRAF V600E mutation analysis. This case provides further insight into the origin and pathogenesis of pigmented astrocytic tumor, additionally highlighting the characteristic CD34 staining pattern.

T cell lymphoblastic lymphoma/leukemia within an adrenocorticotropic hormone and thyroid stimulating hormone positive pituitary adenoma: A cytohistological correlation emphasizing importance of intra-operative squash smear.

We present a rare case of primary pituitary T cell lymphoma/leukemia (T-LBL) in association with adrenocorticotropic hormone (ACTH) and thyroid stimulating hormone (TSH) expressing pituitary adenoma in a 55-year-old woman highlighting the importance of intra-operative squash smears examination. The patient presented with complaints of headache, diminution of vision and recent onset altered sensorium. MRI revealed a mass lesion in the sellar-suprasellar region with non-visualization of pituitary gland separately, extending to involve adjacent structures diagnosed as invasive pituitary macroadenoma. Intra-operative tissue was sent for squash smear examination. The cytology showed a tumor comprising of sheets of immature lymphoid cells intermixed with clusters of pituitary acinar cells with many mitoses and tingible body macrophages. A diagnosis of presence of immature lymphoid cells within the pituitary was offered and differentials of infiltration by lymphoma cells from systemic disease versus primary central nervous lymphoma-like lymphoma arising in the pituitary adenoma were considered. Later paraffin section examination and immunohistochemistry corroborated with the squash findings and a final diagnosis of primary pituitary T cell lymphoma/leukemia in association with ACTH and TSH expressing pituitary adenoma was made. To date, only six cases of primary pituitary T cell lymphomas, including three T-LBL cases, have been reported. This is the seventh case and first one additionally describing cytohistological correlation and importance of intra-operative cytology.

Juxtarenal Aortic Pseudoaneurysm - Right Renal Vein Fistula with Circumaortic Renal Collar-Delayed Manifestation of a Gunshot Injury - an Uncommon Entity Diagnosed with CT Angiography.

BACKGROUND: Delayed presentation of post-traumatic aortic pseudoaneurysm and its fistulous communication with the right renal vein is a very rare entity. Most of the cases described in literature are due to abdominal aortic aneurysm (AAA) rupture into the left renal vein. To the best of our knowledge, communication with the right renal vein has not been described in published literature. Our patient also had a circumaortic renal collar, which is a rare renal vein anomaly. Aortic pseudoaneurysm, its fistulous communication with the right renal vein and circumaortic renal collar in a single patient is of extremely rare occurrence. CASE REPORT: A 29-year-old male presented to the cardiology department with complaints of breathlessness, abdominal pain and hematuria for the last 6 months. On clinical examination there was evidence of audible bruit over the abdomen. He had a past history of a gunshot injury around two years back. CT angiography revealed a large partially calcified pseudoaneurysm arising from the right lateral wall of the abdominal aorta with the neck of the pseudoaneurysm at juxtarenal location with a fistula between the anterior wall of the pseudoaneurysm and the posterior wall of the right renal vein. There was an associated incidental finding of circumaortic left renal vein with gross aneurysmal dilatation of both pre- and retro-aortic part of the renal vein. CONCLUSIONS: Delayed presentation of aortic pseudoaneurysm with its fistulous communication with the right renal vein is a rare entity. CT angiography is a non-invasive modality for diagnosis of the exact site of communication, length of aneurysm, proximal and distal extent of the affected segment and its relationship with surrounding structures.

Aneurysm of Mid and Apical Interventricular Cardiac Septum Dissecting Along the Basal Part - An Uncommon Entity Diagnosed with CT Angiography.

BACKGROUND: Aneurysm of the muscular interventricular septum is a rare entity as compared to the membranous part. Only a few cases of dissecting septal aneurysm have been reported in literature. Two-dimensional echocardiography is the initial diagnostic modality with ECG-gated CT and MRI being non-invasive imaging modalities for comprehensive evaluation. The complications can arise from chronic pressure erosion of the intervening septal myocardium, leading to left-to-right shunting in the form of ventricular septal defect and paradoxical thromboembolism. Radiologists should be aware of imaging findings of interventricular septal aneurysm, because of its rarity of occurrence and complications. CASE REPORT: A 48-year-old male patient presented to a cardiology department with complaints of intermittent chest pain, palpitations and exertional dyspnoea. CT angiography revealed a wide-mouth large aneurysm arising from the mid and apical portion of the interventricular septum dissecting into the basal part. There was associated significant bowing (>15 mm) of the septum and mild obliteration of the right ventricular cavity. Myocardium surrounding the aneurysm was identified with no associated ventricular septal defect (VSD). No evidence of intraventricular clot was found. Catheter angiography confirmed the CT angiographic findings. CONCLUSIONS: Radiologists should be aware of imaging findings of interventricular septal aneurysm, because of its rarity of occurrence, complication in the form of thromboembolism, dissection and intracardiac shunting and mass effect over adjacent cardiovascular structures. Careful scrutiny is essential to avoid labelling of these cases as cardiac masses.

Large Gastric Perforation Sealed by Splenic Lysis: Emphasis on Indirect Signs - A Rare Case Report.

BACKGROUND: Gastric perforation is a life-threatening condition, requiring early and reliable discovery. The delay before surgical treatment is a strong determinant of poor outcome, associated complications and hospitalization costs. By using ultrasound and multi-detector computed tomography (MDCT) we can further evaluate undiagnosed cases of silent gastric perforations presenting with non-specific acute abdomen. Here we bring forth the role of a radiologist in cases of perforation which present with indirect signs involving the organs forming the stomach bed, like the spleen, pancreas and kidney. CASE REPORT: A 25-year-old male patient presented with an acute onset of severe upper abdominal pain radiating to the back and vomiting. MDCT of the abdomen was done which revealed atrophic pancreas with organized collection in the sub-capsular location indenting the superior pole of the left kidney. Spleen was not visualized. The most striking imaging finding in that case was destruction of the splenic parenchyma with protrusion of the remaining tissue into the stomach lumen. The hypothesis behind this was a cascade of events which started with gastric perforation, spillage of highly destructive gastric juice over the stomach bed and finally becoming silent with rapid sealing of the defect by the omentum and the spleen. CONCLUSIONS: Acute abdomen is a diagnostic challenge to a clinician and radiologist with gastric perforation being a great mimicker of other urgent abdominal pathologies. To avoid a delayed diagnosis or a misdiagnosis, familiarity with typical and atypical imaging features is essential as in our case of splenic lysis. It acted as the 2(nd) policeman and provided a great clue to solve the diagnostic dilemma.

B-cell epitope of beta toxin of Clostridium perfringens genetically conjugated to a carrier protein: expression, purification and characterization of the chimeric protein.

Beta toxin (btx) is the prime virulence factor for the pathogenesis of Clostridium perfringens type C strain, known to cause necrotic enteritis and enterotoxaemia in mammalian species. The existing vaccines targeting btx are formaldehyde inactivated culture filtrates of Clostridium. These filtrates raise antigenic load in the host leading to nonspecific and poor responses. The present study aimed to overcome these drawbacks and generate a chimeric protein carrying in silico identified B-cell epitope of btx fused with a carrier protein as a vaccine candidate. Using bioinformatic tools, three stretches of amino acids were predicted as putative B-cell epitopes. One of the epitopes spanning 140-156 amino acid residues was genetically conjugated with B-subunit of heat labile enterotoxin (LTB) of Escherichia coli and expressed as a translational fusion in Vibrio cholerae secretory expression system. High level expression of the recombinant fusion protein rLTB-Btx140-156 was obtained and the protein was successfully purified. The recombinant protein retained the native LTB property to pentamerize and bind to GM1 ganglioside receptor of LTB. The antigenicity of both the epitope and the carrier protein was maintained in fusion protein as indicated by immunoblotting against anti-LTB and anti-btx antibody. The rLTB-Btx140-156 fusion protein therefore can be evaluated as a potential vaccine candidate against C. perfringens.

Immunogenicity and Neutralization Potential of Recombinant Chimeric Protein Comprising the Catalytic Region of Gp63 of Leishmania and LTB against Leishmania Donavani.

AIM: To study the inhibition potential of antibody against a recombinant chimera comprising of the catalytic epitope of gp63 of Leishmania donovani and B subunit of heat-labile enterotoxin [LTB] in the functional activity of L. donovani. BACKGROUND: Visceral leishmaniasis, caused by the protozoan parasite Leishmania donavani, is a major health problem and causes mortality in tropical regions. Protozoan proteases play a crucial role in the pathogenesis of the disease and in establishing infection by countering the host's innate immune responses, namely complement-mediated lysis and phagocytosis. A surface-bound metalloprotease [gp63] has been reported to be a major virulence factor resulting in the evasion of complement- mediated lysis, cleaving host extracellular and intracellular substrates, resulting in intra- phagolysosomal survival Method: The epitope corresponding to the catalytic motif of gp63 of Leishmania donovani has fused with the B subunit of heat-labile enterotoxin, which is known to be immunogenic. The chimera was cloned to a prokaryotic expression vector and purified using Ni NTA affinity chromatography. Antibodies were generated against the purified fusion protein and analyzed for its ability to bind to the gp63 catalytic motif peptide by ELISA. The effect of fusion protein antibody on the functional activity of gp63 was evaluated by assessing the effect of purified IgGs on the protease activity and complement-mediated lysis of L. donovani promastigotes in vitro. RESULTS: The present study reports that a recombinant chimera of the catalytic epitope of gp63 and B subunit of heat-labile enterotoxin [LTB] of E. coli, a potent adjuvant of humoral response can mount significant immune response towards the catalytic epitope. ELISA and Western blot analysis showed that the anti-fusion protein antiserum could recognize the native gp63. Also, it significantly inhibited the protease activity of promastigotes and subsequently increased complement-mediated lysis of the promastigotes in vitro. CONCLUSION: It could be concluded that the hybrid protein containing catalytic motif L. donovani gp63 protein and carrier protein [LTB] could elicit antibodies that could neutralise the functional activity of gp63 and thus could be a potential candidate for subunit leishmaniasis vaccine.

Heterologous expression and biochemical characterization of recombinant alpha phosphoglucomutase from Mycobacterium tuberculosis H37Rv.

Phosphoglucomutase (PGM) plays an important role in polysaccharide capsule formation and virulence in a number of bacterial pathogens. However, the enzyme has not yet been characterized from Mycobacterium tuberculosis (Mtb). Here, we report the biochemical properties of recombinant Mtb-PGM as well as the in silico structural analysis from Mtb H37Rv. The purified recombinant enzyme was enzymatically active with a specific activity of 67.5 U/mg and experimental k(cat) of 70.31 s(-1) for the substrate glucose-1-phosphate. The enzyme was stable in pH range 6.5-7.4 and exhibited temperature optima range between 30 and 40°C. Various kinetic parameters and constants of the rPGM were determined. A structural comparison of Modeller generated 3D Mtb-PGM structure with rabbit muscle PGM revealed that the two enzymes share the same overall heart shape and four-domain architecture, despite having only 17% sequence identity. However, certain interesting differences between the two have been identified, which provide an opportunity for designing new drugs to specifically target the Mtb-PGM. Also, in the absence of the crystal structure of the Mtb-PGM, the modeled structure could be further explored for in silico docking studies with suitable inhibitors.

Solubilization of inclusion body proteins using n-propanol and its refolding into bioactive form.

Inclusion bodies of recombinant human growth hormone (r-hGH) were isolated from Escherichia coli, enriched and solubilized in 100mM Tris buffer containing 6M n-propanol and 2M urea. Around 4 mg/ml of r-hGH from inclusion bodies were solubilized in 6M n-propanol-based buffer containing 2M urea. Existence of native-like secondary structure of r-hGH in 6M n-propanol solution was confirmed by CD and fluorescence spectra. Solubilized r-hGH was subsequently refolded by pulsatile dilution, purified to homogeneity and found to be functionally active. Tris buffer containing 6M n-propanol and 2M urea also effectively solubilized a number of proteins expressed as inclusion bodies in E. coli. Mild solubilization of inclusion body proteins, chaotropic effect of n-propanol at high concentration and kosmotropic effect at lower concentration helped in improved refolding of the solubilized protein. Around 40% of the r-hGH in the form of inclusion body aggregates was refolded into bioactive form while using n-propanol as solubilization agent. Solubilization with 6M n-propanol solution thus can be a viable alternative for achieving high throughput recovery of bioactive protein from inclusion bodies of E. coli.

Defining Delayed Discharges of Inpatients and Their Impact in Acute Hospital Care: A Scoping Review.

BACKGROUND: With the ever-increasing demand on acute healthcare, the hospital discharge process and delayed discharges are considered relevant in achieving optimal performance in clinical settings. The purpose of this paper is to review the literature to identify conceptual and operational definitions of delayed discharges, identify causes and effects of delayed discharges, and also to explore the literature for interventions aimed at decreasing the impact (in terms of reducing the number/rate of delays) of delayed discharges in acute healthcare settings. METHODS: An extensive literature search yielded a total of 26 248 records. Sixty-four research articles were included in the scoping review after considering inclusion/exclusion criteria and the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) search strategy. The following databases were utilized: Cochrane, EBSCO, PubMed, PubMed Central, Medline, and Web of Science. The search was carried out between January 2017 and March 2020 and covered literature ranging from 1990 to 2019. Results were reviewed by authors for duplicates and filtered using the inclusion/ exclusion criteria. Tables were created to classify the chosen articles (n = 64), allowing us to organise findings and results. RESULTS: Conceptual and operational definitions were analysed. In turn, causes and effects of delayed discharges were extracted and represented in diagrammatic format, together with specific interventions used in acute healthcare settings to lessen the effect of delayed discharges. Operational definitions of delayed discharges were found to be more difficult to establish, particularly in the light of the vast number of different scenarios and workplace interventions uncovered in the literature. The main causes of delayed discharges were faulty organisational management, inadequate discharge planning, transfer of care problems, and age. The main effects were bed-blocking, A&E (Accident & Emergency) overcrowding, and financial implications. The main interventions included 'discharge before noon' initiative, 'discharge facilitation tools,' 'discharge delay tracking' mechanisms, and the role of general practitioners and social care staff. CONCLUSION: This paper fills a gap in the fragmented literature on delayed inpatient discharges by providing a researchbased perspective on conceptual and operational definitions, causes and effects, as well as interventions to minimize their impact. The findings and definitions are intended as points of reference for future research.

Scaling up a decentralized offline patient ID generation and matching algorithm to accelerate universal health coverage: Insights from a literature review and health facility survey in Nigeria.

Background: Quality of health service delivery data remains sub-optimal in many Low and middle-income countries (LMICs) despite over a decade of progress in digitization and Health Management Information Systems (HMIS) improvements. Identifying everyone residing in a country utilizing universal civil registration and/or national unique identification number systems especially for vulnerable patients seeking care within the care continuum is an essential part of pursuing universal health coverage (UHC). Many different strategies or candidate digital technologies exist for uniquely identifying and tracking patients within a health system, and the different strategies also have their advantages and trade-offs. The recent approval of Decentralized identifier (DID) core specification by World Wide Web Consortium (W3C) heralds the search for consensus on standard interoperable DID methods. Objective: This paper aims to: (1) assess how candidate Patient Identification Systems fit the digital Patient ID desirable attributes framework in literature; and (2) use insights from Nigeria to propose the scale-up of an offline, interoperable decentralized Patient ID generation and a matching model for addressing network reliability challenges of centralized electronic registries in LMICs. Methods: We combined: (i) systematic review of the literature to identify the characteristics of leading candidates for Patient ID systems, with (ii) review of policies and (iii) quantitative survey of 14 general hospitals in Nigeria's Federal Capital Territory to understand the model(s) of patient ID strategies currently implemented by public hospitals. Results: Evidence from the literature review and quantitative survey showed that no current Patient ID strategy in Nigeria simultaneously meets the six attributes of uniqueness, unchanging, uncontroversial, inexpensive, ubiquitous, and uncomplicated required for ensuring the reliability of unique patient identification systems and of the HMIS more generally. Conclusions: The findings are used to propose a model of algorithms for universal-offline Patient ID generation and matching models that is cost effective and can be easily scaled-up throughout Nigeria. The prototype has promise for generating and validating a universally unique Patient ID given a set of patient characteristics without a central rigid authority. The model can also help to fast-track the implementation of a Master Patient Index (MPI) and interoperability of existing digital health platforms in LMICs.

Standardizing Primary Health Care Referral Data Sets in Nigeria: Practitioners' Survey, Form Reviews, and Profiling of Fast Healthcare Interoperability Resources (FHIR).

BACKGROUND: Referral linkages are crucial for efficient functioning of primary health care (PHC) systems. Fast Healthcare Interoperability Resource (FHIR) is an open global standard that facilitates structuring of health information for coordinated exchange among stakeholders. OBJECTIVE: The objective of this study is to design FHIR profiles and present methodology and the profiled FHIR resource for Maternal and Child Health referral use cases in Ebonyi state, Nigeria-a typical low- and middle-income country (LMIC) setting. METHODS: Practicing doctors, midwives, and nurses were purposefully sampled and surveyed. Different referral forms were reviewed. The union of data sets from surveys and forms was aggregated and mapped to base patient FHIR resource elements, and extensions were created for data sets not in the core FHIR specification. This study also introduced FHIR and its relation to the World Health Organization's (WHO's) International Classification of Diseases. RESULTS: We found many different data elements from the referral forms and survey responses even in urban settings. The resulting FHIR standard profile is published on GitHub for adaptation or adoption as necessary to aid alignment with WHO recommendations. Understanding data sets used in health care and clinical practice for information sharing is crucial in properly standardizing information sharing, particularly during the management of COVID-19 and other infectious diseases. Development organizations and governments can use this methodology and profile to fast-track FHIR standards adoption for paper and electronic information sharing at PHC systems in LMICs. CONCLUSIONS: We presented our methodology for profiling the referral resource crucial for the standardized exchange of new and expectant moms' information. Using data from frontline providers and mapping to the FHIR profile helped contextualize the standardized profile.

Digital Health Solutions and State of Interoperability: Landscape Analysis of Sierra Leone.

BACKGROUND: The government and partners have invested heavily in the health information system (HIS) for service delivery, surveillance, reporting, and monitoring. Sierra Leone's government launched its first digital health strategy in 2018. In 2019, a broader national innovation and digital strategy was launched. The health pillar direction will use big data and artificial intelligence (AI) to improve health care in general and maternal and child health in particular. Understanding the number, distribution, and interoperability of digital health solutions is crucial for successful implementation strategies. OBJECTIVE: This paper presents the state of digital health solutions in Sierra Leone and how these solutions currently interoperate. This study further presents opportunities for big data and AI applications. METHODS: All the district health management teams, all digital health implementing organizations, and a stratified sample of 72 (out of 1284) health facilities were purposefully selected from all health districts and surveyed. RESULTS: The National Health Management Information System's (NHMIS's) aggregate reporting solution populated by health facility forms HF1 to HF9 was, by far, the most used tool. A health facility-based weekly aggregate electronic integrated disease surveillance and response solution was also widely used. Half of the health facilities had more than 2 digital health solutions in use. The different digital health software solutions do not share data among one another, though aggregate reporting data were sent as necessary. None of the respondents use any of the health care registries for patient, provider, health facility, or terminology identification. CONCLUSIONS: Many digital health solutions are currently used at health facilities in Sierra Leone. The government can leverage current investment in HIS from surveillance and reporting for using big data and AI for care. The vision of using big data for health care is achievable if stakeholders prioritize individualized and longitudinal patient data exchange using agreed use cases from national strategies. This study has shown evidence of distribution, types, and scale of digital health solutions in health facilities and opportunities for leveraging big data to fill critical gaps necessary to achieve the national digital health vision.