A CcdB toxin-derived peptide acts as a broad-spectrum antibacterial therapeutic in infected mice.

The bacterial toxin CcdB (Controller of Cell death or division B) targets DNA Gyrase, an essential bacterial topoisomerase, which is also the molecular target for fluoroquinolones. Here, we present a short cell-penetrating 24-mer peptide, CP1-WT, derived from the Gyrase-binding region of CcdB and examine its effect on growth of Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus and a carbapenem- and tigecycline-resistant strain of Acinetobacter baumannii in both axenic cultures and mouse models of infection. The CP1-WT peptide shows significant improvement over ciprofloxacin in terms of its in vivo therapeutic efficacy in treating established infections of S. Typhimurium, S. aureus and A. baumannii. The molecular mechanism likely involves inhibition of Gyrase or Topoisomerase IV, depending on the strain used. The study validates the CcdB binding site on bacterial DNA Gyrase as a viable and alternative target to the fluoroquinolone binding site.

A dimeric proteomimetic prevents SARS-CoV-2 infection by dimerizing the spike protein.

Protein tertiary structure mimetics are valuable tools to target large protein-protein interaction interfaces. Here, we demonstrate a strategy for designing dimeric helix-hairpin motifs from a previously reported three-helix-bundle miniprotein that targets the receptor-binding domain (RBD) of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Through truncation of the third helix and optimization of the interhelical loop residues of the miniprotein, we developed a thermostable dimeric helix-hairpin. The dimeric four-helix bundle competes with the human angiotensin-converting enzyme 2 (ACE2) in binding to RBD with 2:2 stoichiometry. Cryogenic-electron microscopy revealed the formation of dimeric spike ectodomain trimer by the four-helix bundle, where all the three RBDs from either spike protein are attached head-to-head in an open conformation, revealing a novel mechanism for virus neutralization. The proteomimetic protects hamsters from high dose viral challenge with replicative SARS-CoV-2 viruses, demonstrating the promise of this class of peptides that inhibit protein-protein interaction through target dimerization.

MIRRORS: a prospective cohort study assessing the feasibility of robotic interval debulking surgery for advanced-stage ovarian cancer.

OBJECTIVE: To establish the feasibility and safety of robotic interval debulking surgery following the MIRRORS protocol (robot-assisted laparoscopic assessment prior to robotic or open surgery) in women with advanced-stage ovarian cancer. MIRRORS is the first of three planned trials: MIRRORS, MIRRORS-RCT (pilot), and MIRRORS-RCT. METHODS: The participants were patients with stage IIIc-IVb epithelial ovarian cancer undergoing neo-adjuvant chemotherapy, suitable for interval debulking surgery with a pelvic mass ≤8 cm. The intervention was robot-assisted laparoscopic assessment prior to robotic or open interval debulking surgery (MIRRORS protocol). The primary outcome was feasibility of recruitment, and the secondary outcomes were quality of life (EORTC QLQC30/OV28, HADS questionnaires), pain, surgical complications, complete cytoreduction rate (%), conversion to open surgery (%), and overall and progression-free survival at 1 year. RESULTS: Overall, 95.8% (23/24) of patients who were eligible were recruited. Median age was 68 years (range 53-83). All patients had high grade serous histology and were BRCA negative. In total, 56.5% were stage IV, 43.5% were stage III, 87.0% had a partial response, while 13.0% had stable disease by RECIST 1.1. Median peritoneal cancer index was 24 (range 6-38). Following MIRRORS protocol, 87.0% (20/23) underwent robotic interval debulking surgery, and 13.0% (3/23) had open surgery. All patients achieved R<1 (robotic R0=47.4%, open R0=0%). No patients had conversion to open. Median estimated blood loss was 50 mL for robotic (range 20-500 mL), 2026 mL for open (range 2000-2800 mL) (p=0.001). Median intensive care length of stay was 0 days for robotic (range 0-8) and 3 days (range 3-13) for MIRRORS Open (p=0.012). The median length of stay was 1.5 days for robotic (range 1-17), 6 days for open (range 5-41) (p=0.012). The time to chemotherapy was as follows 18.5 days for robotic (range 13-28), 25 days for open (range 22-28) (p=0.139). CONCLUSIONS: Robotic interval debulking surgery appears safe and feasible for experienced robotic surgeons in patients with a pelvic mass ≤8 cm. A randomized controlled trial (MIRRORS-RCT) will determine whether MIRRORS protocol has non-inferior survival (overall and progression-free) compared with open interval debulking surgery.

In Silico Study to Predict the Structural and Functional Consequences of SNPs on Biomarkers of Ovarian Cancer (OC) and BPA Exposure-Associated OC.

BACKGROUND: Recently, we have shown that seven genes, namely GBP5, IRS2, KRT4, LINCOO707, MRPL55, RRS1 and SLC4A11, have prognostic power for the overall survival in ovarian cancer (OC). METHODS: We present an analysis on the association of these genes with any phenotypes and mutations indicative of involvement in female cancers and predict the structural and functional consequences of those SNPS using in silico tools. RESULTS: These seven genes present with 976 SNPs/mutations that are associated with human cancers, out of which 284 related to female cancers. We have then analysed the mutation impact on amino acid polarity, charge and water affinity, leading to the identification of 30 mutations in gynaecological cancers where amino acid (aa) changes lead to opposite polarity, charges and water affinity. Out of these 30 mutations identified, only a missense mutation (i.e., R831C/R804C in uterine corpus endometrial carcinomas, UCEC) was suggestive of structural damage on the SLC4A11 protein. CONCLUSIONS: We demonstrate that the R831C/R804C mutation is deleterious and the predicted ΔΔG values suggest that the mutation reduces the stability of the protein. Future in vitro studies should provide further insight into the role of this transporter protein in UCEC.

Desolvation of Peptide Bond by O to S Substitution Impacts Protein Stability.

Amino acid side chains are key to fine-tuning the microenvironment polarity in proteins composed of polar amide bonds. Here, we report that substituting an oxygen atom of the backbone amide bond with sulfur atom desolvates the thioamide bond, thereby increasing its lipophilicity. The impact of such local desolvation by O to S substitution in proteins was tested by synthesizing thioamidated variants of Pin1 WW domain. We observe that a thioamide acts in synergy with nonpolar amino acid side chains to reduce the microenvironment polarity and increase protein stability by more than 14 °C. Through favorable van der Waals and hydrogen bonding interactions, this single atom substitution significantly stabilizes proteins without altering the amino acid sequence and structure of the native protein.

Convenient synthesis of thioamidated peptides and proteins.

The unique physicochemical properties of a thioamide bond, which is an ideal isostere of an amide bond, have not been fully exploited because of the tedious synthesis of thionated amino acid building blocks. Here, we report a purification-free and highly efficient synthesis of thiobenzotriazolides of Fmoc-protected and orthogonally protected 20 naturally occurring amino acids including asparagine, glutamine, and histidine. The near-quantitative conversion to the respective thioamidated peptides on solid support demonstrates the robustness of the synthetic route. Furthermore, the unaltered incorporation efficiency of thiobenzotriazolides from their stock solution till 48 h suggests their compatibility toward automated peptide synthesis. Finally, utilizing an optimized cocktail of 2% DBU + 5% piperazine for fast Fmoc-deprotection, we report the synthesis of a thioamidated Pin1 WW domain and thioamidated GB1 directly on solid support.

COVID-19 and gynecological cancer: a review of the published guidelines.

On March 11, 2020 the COVID-19 outbreak was declared a 'pandemic' by the World Health Organization. COVID-19 is associated with higher surgical morbidity and mortality. An array of guidelines on the management of cancer during this pandemic have been published since the first reports of the outbreak. This narrative review brings all the relevant information from the guidelines together into one document, to support patient care. We present a detailed review of published guidelines, statements, comments from peer-reviewed journals, and nationally/internationally recognized professional bodies and societies' web pages (in English or with English translation available) between December 1, 2019 and May 27, 2020. Search terms included combinations of COVID, SARS-COV-2, guideline, gynecology, oncology, gynecological, cancer. Recommendations for surgical and oncological prioritization of gynecological cancers are discussed and summarized. The role of minimally invasive surgery, patient perspectives, medico-legal aspects, and clinical trials during the pandemic are also discussed. The consensus is that elective benign surgery should cease and cancer surgery, chemotherapy, and radiotherapy should continue based on prioritization. Patient and staff face-to-face interactions should be limited, and health resources used efficiently using prioritization strategies. This review and the guidelines on which it is based support the difficult decisions currently facing us in gynecological cancer. It is a balancing act: limited resources and a hostile environment pitted against the time-sensitive nature of cancer treatment. We can only hope to do our best for our patients with the resources available to us.

Effect of supplementing pomegranate peel infusion on body growth, feed efficiency, biochemical metabolites and antioxidant status of broiler chicken.

Pomegranate fruit peel is a great source of natural polyphenols. The objective of the present study was to evaluate efficacy of pomegranate peel infusion (PPI) on growth characteristics, feed efficiency, blood metabolites and antioxidant profile of broiler chicken. A total of 200 broiler chickens were randomly assigned to 4 treatments with 5 replicates of 10 birds. Pomegranate peel infusion was supplemented in drinking water to 3 treatment groups in a graded dose. At the end of the trial (42 days), 2 broiler chickens from each pen were sampled for serum and liver tissue. Results revealed that low-dose (50 mL/L) PPI influenced (L: P < 0.001) final body weight, daily body weight gain, and feed conversion ratio. Quadratic effect (Q: P < 0.001) was found in overall body weight, average daily gain in body weight, and average daily feed intake. It was also observed that PPI had significant (L: P < 0.05) hypo-lipidaemic effect. PPI supplementation reduced (L: P < 0.01) lipid peroxidation in all supplemented birds. Reduced glutathione and catalase in the liver tissue was also increased linearly (L: P < 0.05) by PPI supplementation, suggesting that natural polyphenols present in the PPI can stimulate antioxidant defence system. Thus, it could be concluded that low-dose supplementation of pomegranate peel infusion could be of great benefits in broiler chickens as a source of natural antioxidants.

The role of biomarkers in endometrial cancer and hyperplasia: a literature review.

INTRODUCTION: Endometrial cancer is the most common gynaecological cancer and its incidence is rising due to increasing obesity rates. We are also seeing an increasing trend of young women diagnosed with either endometrial cancer or its precancerous state, endometrial hyperplasia. Diagnosis is dependent on invasive testing and there is no screening tool available for either general or high-risk population groups. Whilst vast amounts of research have been undertaken in higher-profile cancers such as ovarian and cervical, endometrial cancer is comparatively less investigated. AIM: In this literature review, we summarise the existing literature in understanding the role of tumour biomarkers for endometrial cancer and its preceding condition of endometrial hyperplasia. METHOD: NICE Healthcare Databases Search tool was used to search Embase, Medline and PubMed databases for relevant articles. CONCLUSION: There is currently no routinely used biomarker in endometrial cancer for diagnostic or prognostic purposes. Given the establishment of new genomic classifications of endometrial cancers, the use of biomarkers to drive therapeutic approaches will be the cornerstone for individualised cancer care in the coming decades.

The Impact of Focality and Centricity on Vulvar Intraepithelial Neoplasia on Disease Progression in HIV+ Patients: A 10-Year Retrospective Study.

BACKGROUND: The impact of lesion focality and centricity in relation to patient outcome and disease recurrence of vulvar intraepithelial neoplasia (VIN) is an understudied area of research, especially in immunocompromised women. The prevalence and incidence of VIN have increased steadily since the 1980s because of the co-existence of human papillomavirus (HPV) and human immunodeficiency virus (HIV). In this study, we retrospectively examined the records of VIN patients to determine the effect of lesion focality and centricity with respect to the interval to disease recurrence. MATERIALS AND METHODS: All women diagnosed with VIN and managed between January 2002 and December 2011 were included (n = 90) and followed up until December 2017. Symptoms at the time of presentation, including HIV positivity (n = 75), were collated, including the influences of multifocality and multicentricity on time to disease recurrence. RESULTS: Multicentricity caused a more rapid recurrence of disease than unicentricity (p = 0.006), whereas multifocality increased the risk of recurrence more than unifocality (p < 0.0001). Viral load in the HIV+ patients was not associated with time to disease recurrence, but the reduced number of CD4+ lymphocytes present in HIV+ patients was. Treatment modalities had no effect on disease recurrence. CONCLUSION: Both focality and centricity have effects on interval to recurrence and final patient outcome, with multifocal disease having a poorer prognosis. Centricity and focality should be recorded at the time of diagnosis and act as a warning for disease recurrence. HIV+ VIN patients with multifocal disease and/or known immunosuppression (low CD4+ lymphocyte counts) should be regarded as "high-risk" patients and treated accordingly.

Neurotrophins, cytokines, oxidative stress mediators and mood state in bipolar disorder: systematic review and meta-analyses.

BACKGROUND: A reliable biomarker signature for bipolar disorder sensitive to illness phase would be of considerable clinical benefit. Among circulating blood-derived markers there has been a significant amount of research into inflammatory markers, neurotrophins and oxidative stress markers.AimsTo synthesise and interpret existing evidence of inflammatory markers, neurotrophins and oxidative stress markers in bipolar disorder focusing on the mood phase of illness. METHOD: Following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) guidelines, a systematic review was conducted for studies investigating peripheral biomarkers in bipolar disorder compared with healthy controls. We searched Medline, Embase, PsycINFO, SciELO and Web of Science, and separated studies by bipolar mood phase (mania, depression and euthymia). Extracted data on each biomarker in separate mood phases were synthesised using random-effects model meta-analyses. RESULTS: In total, 53 studies were included, comprising 2467 cases and 2360 controls. Fourteen biomarkers were identified from meta-analyses of three or more studies. No biomarker differentiated mood phase in bipolar disorder individually. Biomarker meta-analyses suggest a combination of high-sensitivity C-reactive protein/interleukin-6, brain derived neurotrophic factor/tumour necrosis factor (TNF)-α and soluble TNF-α receptor 1 can differentiate specific mood phase in bipolar disorder. Several other biomarkers of interest were identified. CONCLUSIONS: Combining biomarker results could differentiate individuals with bipolar disorder from healthy controls and indicate a specific mood-phase signature. Future research should seek to test these combinations of biomarkers in longitudinal studies.Declaration of interestNone.

Design, Synthesis, and Experimental Validation of Peptide Ligands Targeting Mycobacterium tuberculosis σ Factors.

Transcription in prokaryotes is a multistep process and is primarily regulated at the initiation stage. σ factors are involved in promoter recognition and thus govern prokaryotic gene expression. Mycobacterium tuberculosis (Mtb) σ factors have been previously suggested as important drug targets through large-scale genome analyses. Here we demonstrate the feasibility of specific targeting of Mtb σ factors using designed peptides. A peptide library was generated using three-dimensional structural features corresponding to the interface regions of σ factors and the RNA polymerase. In silico optimization of the peptides, employing structural as well as sequence features, aided specific targeting of σA and σB. We synthesized and characterized the best hit peptide from the peptide library along with other control peptides and studied the interaction of these peptides with σB using biolayer interferometry. The experimental data validate the design strategy. These studies suggest the feasibility of designing specific peptides via in silico methods that bind σB with nanomolar affinity. We note that this strategy can be broadly applied to modulate prokaryotic transcription by designed peptides, thereby providing a tool for studying bacterial adaptation as well as host-pathogen interactions in infectious bacteria.

Methylation of MYLK3 gene promoter region: a biomarker to stratify surgical care in ovarian cancer in a multicentre study.

BACKGROUND: Survival benefit from surgical debulking of ovarian cancer (OC) is well established, but some women, despite total macroscopic clearance of disease, still have poor prognosis. We aimed to identify biomarkers to predict benefit from conventional surgery. METHODS: Clinical data from women debulked for high-stage OC were analysed (Hammersmith Hospital, London, UK; 2001-2014). Infinium's HumanMethylation27 array interrogated tumour DNA for differentially methylated CpG sites, correlated to survival, in patients with the least residual disease (RD; Hammersmith Array). Validation was performed using bisulphite pyrosequencing (Charité Hospital, Berlin, Germany cohort) and The Cancer Genome Atlas' (TCGA) methylation data set. Kaplan-Meier curves and Cox models tested survival. RESULTS: Altogether 803 women with serous OC were studied. No RD was associated with significantly improved overall survival (OS; hazard ratio (HR) 1.25, 95% CI 1.06-1.47; P=0.0076) and progression-free survival (PFS; HR 1.23, 95% CI 1.05-1.43; P=0.012; Hammersmith database n=430). Differentially methylated loci within FGF4, FGF21, MYLK2, MYLK3, MYL7, and ITGAE associated with survival. Patients with the least RD had significantly better OS with higher methylation of MYLK3 (Hammersmith (HR 0.51, 95% CI 0.31-0.84; P=0.01), Charité (HR 0.46, 95% CI 0.21-1.01; P=0.05), and TCGA (HR 0.64, 95% CI 0.44-0.93; P=0.02)). CONCLUSIONS: MYLK3 methylation is associated with improved OS in patients with the least RD, which could potentially be used to determine response to surgery.

Peptide utilizing carbon starvation gene yjiY is required for flagella mediated infection caused by Salmonella.

Peptide metabolism forms an important part of the metabolic network of Salmonella and to acquire these peptides the pathogen possesses a number of peptide transporters. While various peptide transporters known in Salmonella are well studied, very little is known about the carbon starvation (cst) genes, cstA and yjiY, which are also predicted to be involved in peptide metabolism. We investigated the role of these genes in the metabolism and pathogenesis of Salmonella and demonstrated for the first time that cst genes actually participate in transport of specific peptides in Salmonella. Further, we established that the carbon starvation gene yjiY affects the expression of flagella leading to poor adhesion of the bacterium to host cells. In contrast with the previously reported role of the gene cstA in virulence of Salmonella in C. elegans, we showed that yjiY is required for successful colonization of Salmonella in the mouse gut. Thus, cst genes not only contribute to the metabolism of Salmonella but also influence its virulence.

Suppressing the epimerization of endothioamide peptides during Fmoc/t-Bu-based solid phase peptide synthesis.

Despite a number of intriguing utilities associated with thioamide-containing peptides and proteins in the context of biophysics, pharmacology and chemical biology, it has hitherto remained as one of the underexplored territories of peptidomimetics. The synthesis of long mono to multiply substituted endothioamide peptides is invariably accompanied with severe epimerization, oxoamide formation and various other undesired side reactions, resulting in messy product profiles. This has completely restrained their use as novel chemical tools for biological studies. During the chain elongation of an N-terminally located thioamide peptide using the Fmoc/t-Bu chemistry, it becomes vulnerable to the repetitive basic treatments as required for such chemistry. The incompatibility of thioamide moiety with bases as well as strong coupling reagents leads to epimerization as well as other side reactions due to its nucleophilicity, resulting in the loss of the stereochemical identity of the thioamidated amino acid residue. An easy-to-implement and efficient protocol to synthesize long (>10-mer) endothioamide peptides, significantly suppressing epimerization and other side reactions using 10% piperidine/dimethylformamide for 1 min, is reported herein. The novelty of the protocol is shown through the efficient synthesis of a number of 10-12-mer mono to multiply thioamide-substituted peptides with broad substrate scopes. The utility of the protocol in the context of protein engineering and chemical protein synthesis is also shown through the synthesis of a thioamide version of the 16-mer peptide from the B1 domain of protein G. Such a protocol to synthesize long endothioamide peptides would open up avenues toward engineering and accessing novel thiopeptide and thioprotein-based chemical tools, the synthesis of which had been a serious hurdle thus far. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

cis-Peptide Bonds: A Key for Intestinal Permeability of Peptides? .

Recent structural studies on libraries of cyclic hexapeptides led to the identification of common backbone conformations that may be instrumental to the oral availability of peptides. Furthermore, the observation of differential Caco-2 permeabilities of enantiomeric pairs of some of these peptides strongly supports the concept of conformational specificity driven uptake and also suggests a pivotal role of carrier-mediated pathways for peptide transport, especially for scaffolds of polar nature. This work presents investigations on the Caco-2 and PAMPA permeability profiles of 13 selected N-methylated cyclic pentaalanine peptides derived from the basic cyclo(-D-Ala-Ala4 -) template. These molecules generally showed moderate to low transport in intestinal epithelia with a few of them exhibiting a Caco-2 permeability equal to or slightly higher than that of mannitol, a marker for paracellular permeability. We identified that the majority of the permeable cyclic penta- and hexapeptides possess an N-methylated cis-peptide bond, a structural feature that is also present in the orally available peptides cyclosporine A and the tri-N-methylated analogue of the Veber-Hirschmann peptide. Based on these observations it appears that the presence of N-methylated cis-peptide bonds at certain locations may promote the intestinal permeability of peptides through a suitable conformational preorganization.

Azide-alkyne cycloaddition-mediated cyclization of phosphonopeptides and their evaluation as PTP1B binders and enrichment tools.

Protein tyrosine phosphatases (PTPs) are important enzymes in health and disease, and chemical tools are crucial to understand and modulate their biological roles. PTP1B is involved in diabetes, obesity and cancer. One of the main challenges for the design of chemical tools for PTP1B is the homology to TCPTP, making tool selectivity a highly challenging task. Here, we aimed to study if azide-alkyne cycloaddition-mediated cyclization of a peptide inhibitor could increase its selectivity toward PTP1B over TCPTP, and if cyclic and linear peptide binders can be applied as enrichment tools of endogenous PTP1B. While the cyclization of the peptide binders did not improve the selectivity toward PTP1B over TCPTP, it enhanced strongly the efficiency to co-precipitate endogenous PTP1B out of cell lysates. Our results show that fine-tuning the molecular structure of peptidic pull-down baits can greatly enhance their efficiency compared to the parental peptide sequences.

Risk of Ovarian Cancer Relapse score: a prognostic algorithm to predict relapse following treatment for advanced ovarian cancer.

OBJECTIVE: The aim of this study was to construct a prognostic index that predicts risk of relapse in women who have completed first-line treatment for ovarian cancer (OC). METHODS: A database of OC cases from 2000 to 2010 was interrogated for International Federation of Gynecology and Obstetrics stage, grade and histological subtype of cancer, preoperative and posttreatment CA-125 level, presence or absence of residual disease after cytoreductive surgery and on postchemotherapy computed tomography scan, and time to progression and death. The strongest predictors of relapse were included into an algorithm, the Risk of Ovarian Cancer Relapse (ROVAR) score. RESULTS: Three hundred fifty-four cases of OC were analyzed to generate the ROVAR score. Factors selected were preoperative serum CA-125, International Federation of Gynecology and Obstetrics stage and grade of cancer, and presence of residual disease at posttreatment computed tomography scan. In the validation data set, the ROVAR score had a sensitivity and specificity of 94% and 61%, respectively. The concordance index for the validation data set was 0.91 (95% confidence interval, 0.85-0.96). The score allows patient stratification into low (<0.33), intermediate (0.34-0.67), and high (>0.67) probability of relapse. CONCLUSIONS: The ROVAR score stratifies patients according to their risk of relapse following first-line treatment for OC. This can broadly facilitate the appropriate tailoring of posttreatment care and support.

Programmed death ligand-1 over-expression correlates with malignancy and contributes to immune regulation in ovarian cancer.

The programmed death-1 (PD-1) pathway is important in the maintenance of peripheral tolerance and homeostasis through suppression of T cell receptor signaling. As such, it is employed by many tumors as a means of immune escape. We have investigated the role of this pathway in human ovarian cancer (OC) to assess its potential role as a diagnostic and/or prognostic marker and therapeutic target, following recent clinical trial success of antibody therapy directed at this pathway. We show programmed death ligand-1 (PD-L1) expression on monocytes in the ascites and blood of patients with malignant OC is strikingly higher than those with benign/borderline disease, with no overlap in the values between these groups. We characterize the regulation of this molecule and show a role of IL-10 present in ascitic fluid. Flow cytometric analysis of T cells present in the ascites and blood showed a correlation of PD-1 expression with malignant tumors versus benign/borderline, in a similar manner to PD-L1 expression on monocytes. Finally, we demonstrate functional links between PD-L1 expression on monocytes and OC tumor cells with suppression of T cell responses. Overall, we present data based on samples obtained from women with ovarian cancer, suggesting the PD-1 pathway may be used as a reliable diagnostic marker in OC, as well as a viable target for use with PD-1/PD-L1-directed antibody immunotherapy.

Test of long-term uterine survival after allogeneic transplantation in rabbits.

AIM: To see if: (i) a large vessel aortocaval vascular patch technique may bring about long-term graft survival after allogeneic uterine transplantation (UTn) in a rabbit model; and (ii) fertility can be achieved following natural mating post-allogeneic UTn. METHODS: Allogeneic uterine cross transplantations were performed in New Zealand white rabbits using an aortocaval macrovascular patch harvested as part of the uterine allograft. Five rabbit recipients received a uterine graft from five unrelated donor rabbits. All female rabbits were unrelated and were of proven fertility with at least one previous litter each. Tacrolimus was administrated for immunosuppression post-transplant. Natural mating was attempted if long-term survival had been achieved. The main outcome measures were: (i) long-term recipient survival; (ii) long-term adequate uterine perfusion; and (iii) successful pregnancy post-UTn. RESULTS: All five recipient animals survived the surgery with satisfactory immediate postoperative recovery. Recipients 1, 2 and 4 died within the first 4 postoperative days. Both long-term survivors failed to conceive following introduction of a proven male breeder despite evidence of mating. Necropsy at 9 and 11 months showed a lack of patency of uterine cornua at the point of anastomosis, albeit a small uterus in recipient 3 and a reddish brown amorphous material at the site of the transplanted uterus in recipient 5. CONCLUSION: We have demonstrated the feasibility of uterine allotransplantation using a macrovascular patch technique, but could not demonstrate conception because of blocked cornua. To address this, we propose using embryo transfer techniques in order to achieve conception.