Selective dehydrogenation of ammonia borane to polycondensated BN rings catalysed by ruthenium olefin complexes.

Dehydrogenation of ammonia borane to well-defined products is an important but challenging reaction. A dinuclear ruthenium complex with a Ru-Ru bond bearing a diazadiene (dad) unit and olefins as non-innocent ligands catalyzes the highly selective formation of conjugated polycondensed borazine oligomers (BxNxHy), predominantly B21N21H18, the BN analogue of superbenzene.

Copper-associated chronic hepatitis in Cavalier King Charles spaniels.

BACKGROUND: Copper-associated chronic hepatitis (CuCH) is poorly characterised in Cavalier King Charles spaniels (CKCS). METHODS: Hepatic copper accumulation was qualitatively and quantitatively assessed, and blood samples were used for genetic testing to screen for known CuCH-associated genetic variants. RESULTS: The study included 13 CKCS with CuCH and eight unaffected controls. Increased transaminase activities, elevated biliary enzyme concentrations and portal hypertension were documented in 100%, 73% and 38% of dogs with CuCH, respectively. Five dogs had three or more abnormalities in measures of liver function. All 11 dogs with CuCh that underwent genetic testing were homozygous negative for the COMMD1 deletion and ATP7A variant but homozygous positive (n = 7) or heterozygous (n = 4) for the ATP7B variant. Liver histology often demonstrated marked architectural distortion by severe, bridging fibrosis and regenerative nodules with lymphoplasmacytic inflammation. Centrilobular copper accumulation characterised early cases with minimal fibrosis. When fibrosis was significant, copper was often differentially concentrated within regenerative nodules. Chelation therapy resolved laboratory derangements and portal hypertension in five of seven dogs. Of the 7 non-surviving dogs with CuCH, 6 had not received chelation therapy. LIMITATIONS: Limitations include a small cohort size and the lack of pedigree analyses to corroborate heritability. CONCLUSIONS: CuCH should be considered in CKCS with suspected liver disease. Long-term prognosis seems favourable in dogs receiving chelation therapy, notwithstanding the presence of previously reported negative prognostic markers.

Surgical management of a laryngeal rhabdomyosarcoma in a cat.

Case summary: An 11-year-old male castrated British Shorthair was referred for investigations into an upper respiratory tract mass. A partial laryngectomy was performed to excise the mass. Marginal resection of the mass involved excision of parts of the thyroid cartilage and left arytenoid cartilage. A tracheostomy tube was maintained for 48 h postoperatively. The cat recovered without complication and was discharged at 72 h postoperatively. Histopathology of the mass was deemed most consistent with a rhabdomyosarcoma (RMS). Relevance and novel information: Telephone follow-up 12 months postoperatively confirmed resolution of the clinical signs. To our knowledge, this is the first report of a laryngeal RMS in a cat. RMS should be considered a differential diagnosis for a laryngeal mass in a cat. This case demonstrates that resection via a partial laryngectomy may be a viable therapeutic option.

Cross-species oncogenomics offers insight into human muscle-invasive bladder cancer.

BACKGROUND: In humans, muscle-invasive bladder cancer (MIBC) is highly aggressive and associated with a poor prognosis. With a high mutation load and large number of altered genes, strategies to delineate key driver events are necessary. Dogs and cats develop urothelial carcinoma (UC) with histological and clinical similarities to human MIBC. Cattle that graze on bracken fern also develop UC, associated with exposure to the carcinogen ptaquiloside. These species may represent relevant animal models of spontaneous and carcinogen-induced UC that can provide insight into human MIBC. RESULTS: Whole-exome sequencing of domestic canine (n = 87) and feline (n = 23) UC, and comparative analysis with human MIBC reveals a lower mutation rate in animal cases and the absence of APOBEC mutational signatures. A convergence of driver genes (ARID1A, KDM6A, TP53, FAT1, and NRAS) is discovered, along with common focally amplified and deleted genes involved in regulation of the cell cycle and chromatin remodelling. We identify mismatch repair deficiency in a subset of canine and feline UCs with biallelic inactivation of MSH2. Bovine UC (n = 8) is distinctly different; we identify novel mutational signatures which are recapitulated in vitro in human urinary bladder UC cells treated with bracken fern extracts or purified ptaquiloside. CONCLUSION: Canine and feline urinary bladder UC represent relevant models of MIBC in humans, and cross-species analysis can identify evolutionarily conserved driver genes. We characterize mutational signatures in bovine UC associated with bracken fern and ptaquiloside exposure, a human-linked cancer exposure. Our work demonstrates the relevance of cross-species comparative analysis in understanding both human and animal UC.

Characterization of a novel interaction of the Nup159 nucleoporin with asymmetrically localized spindle pole body proteins and its link with autophagy.

Both the spindle microtubule-organizing centers and the nuclear pore complexes (NPCs) are convoluted structures where many signaling pathways converge to coordinate key events during cell division. Interestingly, despite their distinct molecular conformation and overall functions, these structures share common components and collaborate in the regulation of essential processes. We have established a new link between microtubule-organizing centers and nuclear pores in budding yeast by unveiling an interaction between the Bfa1/Bub2 complex, a mitotic exit inhibitor that localizes on the spindle pole bodies, and the Nup159 nucleoporin. Bfa1/Bub2 association with Nup159 is reduced in metaphase to not interfere with proper spindle positioning. However, their interaction is stimulated in anaphase and assists the Nup159-dependent autophagy pathway. The asymmetric localization of Bfa1/Bub2 during mitosis raises the possibility that its interaction with Nup159 could differentially promote Nup159-mediated autophagic processes, which might be relevant for the maintenance of the replicative lifespan.

Copper toxicosis in Bedlington terriers is associated with multiple independent genetic variants.

BACKGROUND: Bedlington terrier copper toxicosis (CT) is due to a homozygous exon deletion in COMMD1. CT also occurs in Bedlingtons lacking this deletion. An association with two ABCA12 single nuceotide polymorphism (SNP) splice variants was reported. Labrador retriever CT is associated with a missense mutation in ATP7B, and with a protective mutation in ATP7A. METHODS: Liver and DNA samples from 24 affected and 10 unaffected Bedlingtons were assessed for copper and genetic variants. Allelic frequencies were compared. The ATP7B mutation frequency was investigated in 144 dogs of other breeds. RESULTS: The ABCA12 SNPs showed no differences between groups. The COMMD1 deletion was less frequent in unaffected than in affected dogs and in affected dogs post-2001 than pre-2001. The ATP7B mutation was more frequent in affected than unaffected Bedlingtons. Thirty-five of 144 dogs of other breeds were homo- or heterozygous for the ATP7B mutation. The ATP7A mutation was absent from Bedlingtons. LIMITATIONS: Clinical information and qualitative copper measurements were unavailable for most dogs. CONCLUSION: The COMMD1 deletion remains present in Bedlington terriers but is no longer the primary cause of CT. ABCA12 SNPs were not associated with CT. The ATP7B:c.4358G>A mutation was significantly associated with Bedlington CT and was more common in dogs of this breed than in the 144 dogs of other breeds.

The ultrasonographic appearance of renal medullary striations and their association with renal disease and renal histopathology in domestic cats.

Medullary striations (MS) have been anecdotally observed on ultrasound of feline kidneys; however, their significance is unknown. Aims of this retrospective, case control, pilot study were to describe the appearance, prevalence, and clinicopathological correlates of MS in a referral feline population. Still images from 1247 feline abdominal ultrasound studies performed between 2011 and 2021 were reviewed. Cats with MS were identified and compared with age-matched controls. Serum urea, creatinine, calcium, phosphate, and calcium-phosphate-product, plus urine specific gravity, urine protein: creatinine ratio (UPC), prevalence of active sediment (defined as > 5 red (RBC) or white blood cells (WBC) per high-power field) and prevalence of positive urine culture were compared between MS and control groups using the Mann-Whitney U test or Fisher's Exact test. Data are presented as median [range]. 27 cats were identified as having MS, giving a prevalence of 2.2% with a significantly higher proportion being seen in males (P = 0.018). Medullary striation cats had significantly higher UPC values than controls (0.46 [0.16-7.57] vs. 0.16 [0.07-2.27]; P = 0.006). Cats with MS were more likely to have active urinary sediments (39% vs 8%, P = 0.023), but no difference in prevalence of positive urinary cultures was observed between groups. There was no significant difference in other parameters between MS and control cats. Renal histopathology performed in three MS cats revealed focal regions of linear medullary fibrosis. Medullary striations are associated with proteinuria and urinary tract inflammation in cats, which may reflect renal tubular dysfunction and/or inflammation. Hence identification might allow for earlier detection of renal pathology.

Somatic mutation rates scale with lifespan across mammals.

The rates and patterns of somatic mutation in normal tissues are largely unknown outside of humans1-7. Comparative analyses can shed light on the diversity of mutagenesis across species, and on long-standing hypotheses about the evolution of somatic mutation rates and their role in cancer and ageing. Here we performed whole-genome sequencing of 208 intestinal crypts from 56 individuals to study the landscape of somatic mutation across 16 mammalian species. We found that somatic mutagenesis was dominated by seemingly endogenous mutational processes in all species, including 5-methylcytosine deamination and oxidative damage. With some differences, mutational signatures in other species resembled those described in humans8, although the relative contribution of each signature varied across species. Notably, the somatic mutation rate per year varied greatly across species and exhibited a strong inverse relationship with species lifespan, with no other life-history trait studied showing a comparable association. Despite widely different life histories among the species we examined-including variation of around 30-fold in lifespan and around 40,000-fold in body mass-the somatic mutation burden at the end of lifespan varied only by a factor of around 3. These data unveil common mutational processes across mammals, and suggest that somatic mutation rates are evolutionarily constrained and may be a contributing factor in ageing.

Can the neutrophil count from hepatic fine-needle aspirate cytology be used to diagnose hepatitis in dogs? A pilot study.

BACKGROUND: The cytologic diagnosis of inflammation on canine hepatic aspirates can be confounded by neutrophilic infiltrates in the liver of dogs with nodular regeneration, by extramedullary hematopoiesis, and by marked blood contamination. OBJECTIVES: We aimed to assess the association between neutrophil counts on hepatic cytology and the histopathologic diagnosis in dogs with hepatitis and non-inflammatory hepatopathy. We also sought to determine a cut-off value for the cytologic diagnosis of hepatitis. METHODS: In a retrospective blinded pilot study, three observers independently reviewed hepatic aspirates that had corresponding histopathologic examinations performed within 2 days. The number of neutrophils per 200 hepatocytes was determined and averaged among observers. Only neutrophils within or directly in contact with a cluster of ≥5 hepatocytes were counted, and only intact hepatocytes within an approximate monolayer were included. Data are presented as the median (range), and the Mann-Whitney U test is used to make comparisons between groups. RESULTS: Eighteen cases were included (13 hepatitis and five vacuolar hepatopathy). Aspirates with a histopathologic diagnosis of hepatitis had increased numbers of neutrophils compared with those of vacuolar hepatopathy (7.7 [0.3-18.3] vs 3.0 [1.0-5.3]; P = .038). Receiver operating characteristic curve analysis indicated that ≥6 neutrophils were 61.5% (CI 31.6%-86.1%) sensitive and 100% (CI 47.8%-100%) specific for identifying hepatitis. CONCLUSIONS: Liver aspirates from hepatitis cases have a higher number of neutrophils on cytology compared with those from vacuolar hepatopathy; however, larger studies, including those with dogs with other liver pathologies, are required. Identification of six or more neutrophils per 200 hepatocytes is highly suggestive of hepatitis.

The Learning Curve for Peroral Endoscopic Myotomy in Latin America: A Slide to the Right?

BACKGROUND/AIMS: Peroral endoscopic myotomy (POEM) has been increasingly used for achalasia in Latin America, where Chagas disease is prevalent, and this makes POEM more challenging. The aim of this study was to determine the learning curve for POEM in Latin America. METHODS: Patients undergoing POEM in Latin America with a single operator were included from a prospective registry over 4 years. Non-linear regression and cumulative sum control chart (CUSUM) analyses were conducted for the learning curve. RESULTS: A total of 125 patients were included (52% male; mean age, 59 years), of which 80 had type II achalasia (64%), and 38 had Chagas disease (30%). The average pre-procedure and post-procedure Eckardt scores were 6.79 and 1.87, respectively. Technical success was achieved in 93.5% of patients, and clinical success was achieved in 88.8%. Adverse events occurred in 27 patients (22%) and included bleeding (4 patients), pneumothorax (4 patients), mucosal perforation (13 patients), mediastinitis (2 patients), and leakage (4 patients).
The CUSUM chart showed a median procedure time of 97 min (range, 45-196 min), which was achieved at the 61st procedure. Procedure duration progressively decreased, with the last 10 procedures under 50 min approaching a plateau (p-value <0.01). CONCLUSION: Mastering POEM in Latin America requires approximately 61 procedures for both POEM efficiency and to accomplish the procedure within 97 minutes.

Correlation between cytologic features and histologic grades in cutaneous and subcutaneous soft tissue sarcomas in dogs-A pilot study.

Currently, canine soft tissue sarcoma (STS) grading is based on histopathology. In humans, several studies have demonstrated concordance between cytologic grading systems for STS and histologic grade. The aim of this study was to correlate several cytologic parameters (smear cellularity, anisokaryosis, nucleolar malignancy score, multinucleation, and the number of mitotic figures per 200 cells) that form part of a human STS cytologic grading system, with histologic grades of canine cutaneous and subcutaneous STS. Three observers (blinded) reviewed the cytologic preparations independently from cases with confirmed histologic diagnoses of STS. A cytologic grading score was assigned for each parameter. Correlations between cytologic grading scores (averaged between observers) and histologic grades were assessed using Spearman's correlation coefficient, with statistical significance defined as P < .05. Twenty-one cases were included in the study (10 Grade I STS, nine Grade II STS, and two Grade III STS). The number of mitotic figures (≥3) per 200 cells was the only parameter that showed a significant but weak, positive correlation with histologic grade (rs  = .469; P = .032). No Grade I tumors had ≥3 mitotic figures per 200 cells; however, ≥3 mitotic figures per 200 cells were only observed in 33% of Grade II tumors and 50% (one out of two) of the Grade III tumors. This pilot study suggests that an increased number of mitotic figures seen on cytology might correlate with higher grade STS; however, the sensitivity of this parameter for grading STS appears to be low.

Peripheral blood cell ratios as prognostic factors in canine diffuse large B-cell lymphoma treated with CHOP protocol.

Diffuse large B-cell lymphoma (DLBCL) is the most common haematopoietic tumour in dogs and recognized as clinical model for its human counterpart. Recently, neutrophil-to-lymphocyte (NLR) and lymphocyte-to-monocyte (LMR) ratios have been shown to predict time-to-progression (TTP) and lymphoma-specific survival (LSS) in dogs with DLBCL treated with CHOP-based chemotherapy. We retrospectively evaluated in 59 dogs diagnosed with DLBCL the prognostic value of haematological parameters and derived ratios: NLR, LMR, platelet-to-lymphocyte (PLR) and platelet-to-neutrophil (PNR) ratios for TTP, LSS and associated secondary end-points (time-to-progression-rate [TTPR] and lymphoma-specific survival-rate [LSSR]) as rates at 180 and 365 days. PNR is an independent prognostic marker (p ≤ .001) for TTPR/180 and 365 days, dogs with a PNR above 0.032 were more likely to progress before 180 days (sensitivity 46.5%, specificity 87.5%, p = .004). On univariate analysis, NLR showed a prognostic significance for LSSR/180 (p = .006) and LSSR/365 (p = .009). A baseline NLR value below 7.45 was positively associated with survival at 180 days (sensitivity 52%, specificity 85.3%, p = .025). The presence of substage b, was associated with early progression and decreased survival at 180 days (p = .031). Anaemia significantly reduced LSSR at 365 days (p = .028). This is the first study evaluating PLR and PNR in canine DLBCL and demonstrates that PNR could be a predictor of early lymphoma progression. Since peripheral blood cell composition can be affected by several non-oncological causes, the development of larger multicenter studies with homogeneous inclusion criteria could help to better determine the true predictive values of blood cell ratios in dogs' DLBCL treated with CHOP chemotherapy.

Multimodality characteristics of multifocal choroid plexus carcinoma with bilateral calvarial defects in a dog.

An 8-year-old male intact miniature poodle presented for blindness, obtundation, tetraparesis, and vestibular signs. Magnetic resonance imaging, radiography, and ultrasound revealed a left piriform lobe lesion, right cerebellar and left brainstem lesions, and hydrocephalus and bilateral calvarial defects. Histopathology confirmed a choroid plexus carcinoma with meningeal and intraventricular metastases. The calvarial defect did not show evidence of necrosis, osteoclastic resorption, inflammation or neoplastic infiltration, reflecting a quiescent calvarial atrophy or dysplasia. These novel findings supported inclusion of bone atrophy secondary to chronic increased intracranial pressure as a differential diagnosis for large calvarial defects in dogs with choroid plexus carcinoma.

Breed-related expression patterns of Ki67, γH2AX, and p21 during ageing in the canine liver.

Cellular senescence is a molecular hallmark of ageing that is associated with multiple pathologies, and DNA damage marker γH2AX, together with cell cycle inhibitor p21, have been used as senescence markers in multiple species including dogs. Idiopathic canine chronic hepatitis has recognised breed-related differences in predisposition and prognosis, but reasons behind this are poorly understood. This retrospective study using archived post mortem tissue aimed to provide insight into liver ageing in 51 microscopically normal canine livers across seven breed categories, including those with and without increased risk of chronic hepatitis. Immunohistochemistry was conducted for γH2AX, p21, and cell proliferation marker Ki67, and the mean number of positive hepatocytes per high power field was determined. All three markers were strongly correlated to each other, but no age-dependent expression was seen in the combined study population. Overall expression levels were low in most dogs, with median values representing less than 1.5% of hepatocytes, but this increased to 20-30% in individual dogs at the upper end of the range. Individual breed differences were noted in two breeds that have increased risk of chronic hepatitis, with English Springer Spaniels having lower expression of Ki67 than other dogs, and Labradors having higher expression of Ki67 and γH2AX than other dogs. These results warrant further investigation in these breeds and highlight a need to validate reliable markers of cellular senescence in dogs.

Canine lymphoma and vector-borne diseases: Molecular and serological evaluation of a possible complicity.

Lymphoma is the most common haematological malignancy in dogs and its aetiology is largely unknown. The presence of canine vector-borne agents (CVBD) in lymphoma tissues has been described and its causative effects questioned. We intended to evaluate the presence and extent of Leishmania infantum, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae infection in dogs with lymphoma. Sixty-one dogs, living in the Lisbon metropolitan area, with a diagnosis of lymphoma were enrolled. Immunofluorescence assays were used to detect serum IgG's. The presence of DNA from CVBD agents in tumour tissue was assessed by PCR. All dogs tested negative for B. henselae, A. phagocytophilum and E. canis by both serology and PCR. Regarding L. infantum, 8.2% (n = 5) of the dogs had a positive serologic result. L. infantum DNA was detected in two samples of diffuse large B-cell lymphoma (DLBCL). These results show an increased, but not significant, seropositivity (8.2% vs 7.9%) and molecular detection (3.3% vs 1.2%) for L. infantum in dogs with lymphoma, when compared to the reported canine population in the same geographical area. We could not identify an association between lymphoma and E. canis, A. phagocytophilum, B. henselae or Leishmania infantum infection in the studied population. Nevertheless, further studies, following dogs trough their CVBD disease evolution, are worthwhile and may help clarify a possible role of CVBD agents in lymphomagenesis.

Polo-like kinase acts as a molecular timer that safeguards the asymmetric fate of spindle microtubule-organizing centers.

The microtubules that form the mitotic spindle originate from microtubule-organizing centers (MTOCs) located at either pole. After duplication, spindle MTOCs can be differentially inherited during asymmetric cell division in organisms ranging from yeast to humans. Problems with establishing predetermined spindle MTOC inheritance patterns during stem cell division have been associated with accelerated cellular aging and the development of both cancer and neurodegenerative disorders. Here, we expand the repertoire of functions Polo-like kinase family members fulfill in regulating pivotal cell cycle processes. We demonstrate that the Plk1 homolog Cdc5 acts as a molecular timer that facilitates the timely and sequential recruitment of two key determinants of spindle MTOCs distribution, that is the γ-tubulin complex receptor Spc72 and the protein Kar9, and establishes the fate of these structures, safeguarding their asymmetric inheritance during Saccharomyces cerevisiae mitosis.

How does per-oral endoscopic myotomy compare to Heller myotomy? The Latin American perspective.

Background and study aims Both Heller myotomy (HM) and per-oral endoscopic myotomy (POEM) are efficacious therapies for achalasia. The efficacy and safety of POEM vs HM in Latin America and specifically in patients with Chagas disease is unknown. Patients and methods Consecutive patients undergoing either HM or POEM for achalasia were included from nine Latin American centers in a prospective registry over 5 years. Technical success was defined as undergoing a successful myotomy. Clinical success was defined as achieving an Eckardt score < 3. Data on demographics, procedure info, Eckardt score, and adverse events (AEs) were collected. Student's t test, Chi squared, and logistic regression analyses were conducted. Results One hundred thirty-three patients were included (59 male; 44 %; mean age 47). POEM was performed in 69 patients, HM in 64 patients. A total of 35 patients had Chagas disease, 17 of 69 in the POEM group, 18 of 64 in the HM group. Both groups had significant reduction in Eckardt scores ( P  < 0.00001), but successful initial therapy was significantly higher in the POEM group compared to the HM group ( P  = 0.01304). AEs were similar in both group (17 % vs 14 %) and consisted of pneumothorax (n = 3 vs 2), bleeding requiring transfusion (n = 3 vs 2), and mediastinitis (n = 3 vs 1). Hospital stay was longer in the HM group than in the POEM group ( P  < 0.00001). In the Chagas subgroup, post-procedure Eckardt score in the POEM group was significantly reduced by 5.71 points ( P  < 0.00001) versus 1.56 points in the HM group ( P  = 0.042793). Conclusion Both HM and POEM are efficacious for achalasia, but POEM was associated with higher initial therapy success and shorter hospital stay in Latin America. In Chagas patients with achalasia, POEM was significantly more effective than HM.

A guiding torch at the poles: the multiple roles of spindle microtubule-organizing centers during cell division.

The spindle constitutes the cellular machinery that enables the segregation of the chromosomes during eukaryotic cell division. The microtubules that form this fascinating and complex genome distribution system emanate from specialized structures located at both its poles and known as microtubule-organizing centers (MTOCs). Beyond their structural function, the spindle MTOCs play fundamental roles in cell cycle control, the activation and functionality of the mitotic checkpoints and during cellular aging. This review highlights the pivotal importance of spindle-associated MTOCs in multiple cellular processes and their central role as key regulatory hubs where diverse intracellular signals are integrated and coordinated to ensure the successful completion of cell division and the maintenance of the replicative lifespan.

Asymmetric cell division and replicative aging: a new perspective from the spindle poles.

Although cell division is usually portrayed as an equitable process by which a progenitor cell originates two identical daughter cells, there are multiple examples of asymmetric divisions that generate two cells that differ in their content, morphology and/or proliferative potential. The capacity of the cells to generate asymmetry during their division is of paramount biological relevance, playing essential roles during embryonic development, cellular regeneration and tissue morphogenesis. Problems with the proper establishment of asymmetry and polarity during cell division can give rise to cancer and neurodevelopmental disorders, as well as to also accelerate cellular aging. Interestingly, the microtubule organizing centers that orchestrate the formation of the mitotic spindle have been described among the cellular structures that can be differentially allocated during asymmetric cell divisions. This mini-review focuses on recent research from our group and others uncovering a role for the non-random distribution of the spindle-associated microtubule organizing centers in the differential distribution of aging factors during asymmetric mitoses and therefore in the maintenance of the replicative lifespan of the cells.