Is occlusion of the main pancreatic duct by thermal ablation really safe? A surgical innovation assessed according to IDEAL recommendations.

INTRODUCTION: Pre-clinical studies suggest that thermal ablation of the main pancreatic duct (TAMPD) is more recommendable than glue for reducing postoperative pancreatic fistula (POPF). Our aims were (1) to analyze the changes in the pancreas of patients after TAMPD and (2) to correlate the clinical findings with those obtained from a study on an animal model. MATERIALS AND METHODS: A retrospective early feasibility study of a marketed device for a novel clinical application was carried out on a small number of subjects (n = 8) in whom TAMPD was conducted to manage the pancreatic stump after a pancreatectoduodenectomy (PD). Morphological changes in the remaining pancreas were assessed by computed tomography for 365 days after TAMPD. RESULTS: All the patients showed either Grade A or B POPF, which generally resolved within the first 30 days. The duct's maximum diameter significantly increased after TAMPD from 1.5 ± 0.8 mm to 8.6 ± 2.9 mm after 7 days (p = .025) and was then reduced to 2.6 ± 0.8 mm after 365 days PO (p < .0001). The animal model suggests that TAMPD induces dilation of the duct lumen by enzymatic digestion of ablated tissue after a few days and complete exocrine atrophy after a few weeks. CONCLUSIONS: TAMPD leads to long-term exocrine pancreatic atrophy by completely occluding the duct. However, the ductal dilatation that occurred soon after TAMPD could even favor POPF, which suggests that TAMPD should be conducted several weeks before PD, ideally by digestive endoscopy.

Comparison of two radiofrequency-based hemostatic devices: saline-linked bipolar vs. cooled-electrode monopolar.

PURPOSE: To characterize the coagulation zones created by two radiofrequency (RF)-based hemostatic devices: one comprised an internally cooled monopolar electrode and the other comprised externally irrigated bipolar electrodes (saline-linked). MATERIALS AND METHODS: RF-induced coagulation zones were created on ex vivo and in vivo porcine models. Computer modeling was used to determine the RF power distribution in the saline-linked device. RESULTS: Both external (irrigation) and internal cooling effectively prevented tissue sticking. Under ex vivo conditions in 'painting' application mode, coagulation depth increased with the applied power: 2.8 - 5.6 mm with the 3-mm monopolar electrode, 1.6 - 6.0 mm with the 5-mm monopolar electrode and 0.6 - 3.2 mm with the saline-linked bipolar electrodes. Under in vivo conditions and using spot applications, the 3-mm monopolar electrode created coagulation zones of similar depth to the saline-linked bipolar electrodes (around 3 mm), while the 5-mm monopolar electrode created deeper coagulations (4.5 - 6 mm) with less incidence of popping. The presence of saline around the saline-linked bipolar electrodes meant that a significant percentage of RF power (50 - 80%) was dissipated by heating in the saline layer. Coagulation zones were histologically similar for all the tested devices. CONCLUSIONS: Both external (irrigation) and internal cooling in hemostatic RF devices effectively prevent tissue sticking and create similar coagulation zones from a histological point of view. Overall, saline-linked bipolar electrodes tend to create shallower coagulations than those created with an internally cooled monopolar electrode.

Sterile or nonantibiotic-responsive pustular dermatitis and canine leishmaniosis: a 14 case series description and a statistical association study on 2420 cases.

Background - No striking clinical and histopathological features of pustular dermatitis (PustD) in dogs suffering from canine leishmaniosis (CanL) have been identified; an association between CanL and PustD has not been demonstrated. Objectives - To characterize a series of dogs affected by CanL and pruritic PustD, and to evaluate a possible association between the two conditions. Conclusions - An association exists between PustD and CanL. At least in Leishmania-endemic areas, CanL should be ruled out before attempting an immunosuppressive treatment in dogs with PustD with the aforementioned characteristics. Staging of CanL through diagnostic procedures besides immunohistochemistry and PCR is recommended. Anti-leishmania treatment and short-to-medium courses of low-dose anti-inflammatory or immunomodulatory drugs are effective in controlling the clinical signs of PustD.

Development of a catheter-based technique for endoluminal radiofrequency sealing of pancreatic duct.

Introduction: Endoluminal sealing of the pancreatic duct by glue or sutures facilitates the management of the pancreatic stump. Our objective was to develop a catheter-based alternative for endoluminal radiofrequency (RF) sealing of the pancreatic duct. Materials and methods: We devised a novel RF ablation technique based on impedance-guided catheter pullback. First, bench tests were performed on ex vivo models to tune up the technique before the in vivo study, after which endoluminal RF sealing of a ∼10 cm non-transected pancreatic duct was conducted on porcine models using a 3 Fr catheter. After 30 days, sealing effectiveness was assessed by a permeability test and a histological analysis. Results: The RF technique was feasible in all cases and delivered ∼5 W of power on an initial impedance of 308 ± 60 Ω. Electrical impedance evolution was similar in all cases and provided guidance for modulating the pullback speed to avoid tissue sticking and achieve a continuous lesion. During the follow-up the animals rate of weight gain was significantly reduced (p < 0.05). Apart from signs of exocrine atrophy, no other postoperative complications were found. At necropsy, the permeability test failed and the catheter could not be reintroduced endoluminally, confirming that sealing had been successful. The histological analysis revealed a homogeneous exocrine atrophy along the ablated segment in all the animals. Conclusions: Catheter-based RF ablation could be used effectively and safely for endoluminal sealing of the pancreatic duct. The findings suggest that a fully continuous lesion may not be required to obtain complete exocrine atrophy.

Endoluminal radiofrequency ablation of the main pancreatic duct is a secure and effective method to produce pancreatic atrophy and to achieve stump closure.

Radiofrequency energy has been used both experimentally and clinically to manage the pancreatic remnant after distal pancreatectomies. Our goal was to determine whether endoluminal radiofrequency (RF) ablation of the main pancreatic duct in large animals would be more efficient than glue occlusion as an exocrine pancreatic atrophy-inducing procedure. Thirty-four Landrace pigs were assigned to either the transpapilar (n = 16) or transection (n = 18) groups. The transection implied the pancreas neck was severed. In each of these groups the remaining distal pancreatic duct was occluded either by RF or by glue. In the transpapilar group complete atrophy was observed in all the RF cases, while atrophy was incomplete in all the members of the glue subgroup. The failure rate of the main pancreatic duct (usually expressed by a pseudocyst) in the transection groups was dramatically higher in the glue subgroup than the RF subgroups (9 out of 9 and 1 out of 9, respectively) and postoperative mortality occurred only in the glue subgroup (3 out of 9). These results show the superiority of endoluminal RF ablation over glue for main pancreatic duct occlusion, as seen by the degree of atrophy and fewer postoperative pancreatic fistulas.

Topical polyhydroxy acid treatment for autosomal recessive congenital ichthyosis in the golden retriever: a prospective pilot study.

BACKGROUND: Autosomal recessive congenital ichthyosis (ARCI) in golden retrievers is due to a PNPLA1 gene mutation, which plays a role in epidermal lipid organization and metabolism. Topical therapies are used to reduce scaling; however, there are few published efficacy studies. OBJECTIVES: To examine the efficacy of topical treatment based on gluconolactone, a polyhydroxy acid with known beneficial effects on stratum corneum structure. ANIMALS: Sixteen golden retriever dogs with clinical signs of ARCI and PCR-confirmed PNPLA1 gene mutation. METHODS: This was a prospective, multicentre, noncontrolled study. Dogs were treated with a shampoo and lotion containing gluconolactone and other hydroxyl acids. Treatments were administered initially twice weekly for two weeks, then once weekly for two weeks and finally once monthly. Examinations were performed prior to and at 14 and 30 days of treatment to assess scaling, presence of other skin lesions and pruritus. In two dogs, pre- and 30 day post-treatment, skin biopsies were obtained. RESULTS: The extent and size of the scales were reduced by 60% and 75% after 14 and 30 days of treatment, respectively (P < 0.001). In 20% of the dogs, scaling was no longer observed after the first 30 days of treatment. No other skin lesions or pruritus were observed in any dog. Post-treatment biopsies showed normalization of the stratum corneum morphology and reduced hyperpigmentation. CONCLUSION AND CLINICAL IMPORTANCE: The frequent use of a shampoo and lotion containing gluconolactone may be an effective measure to improve skin scaling in golden retrievers with ARCI.

Avoiding neuromuscular stimulation in liver irreversible electroporation using radiofrequency electric fields.

Electroporation-based treatments typically consist of the application of high-voltage dc pulses. As an undesired side effect, these dc pulses cause electrical stimulation of excitable tissues such as motor nerves. The present in vivo study explores the use of bursts of sinusoidal voltage in a frequency range from 50 kHz to 2 MHz, to induce irreversible electroporation (IRE) whilst avoiding neuromuscular stimulation. A series of 100 dc pulses or sinusoidal bursts, both with an individual duration of 100 µs, were delivered to rabbit liver through thin needles in a monopolar electrode configuration, and thoracic movements were recorded with an accelerometer. Tissue samples were harvested three hours after treatment and later post-processed to determine the dimensions of the IRE lesions. Thermal damage due to Joule heating was ruled out via computer simulations. Sinusoidal bursts with a frequency equal to or above 100 kHz did not cause thoracic movements and induced lesions equivalent to those obtained with conventional dc pulses when the applied voltage amplitude was sufficiently high. IRE efficacy dropped with increasing frequency. For 100 kHz bursts, it was estimated that the electric field threshold for IRE is about 1.4 kV cm-1 whereas that of dc pulses is about 0.5 kV cm-1.

Characterization of the canine rostral ventricular-subventricular zone: Morphological, immunohistochemical, ultrastructural, and neurosphere assay studies.

The mammalian ventricular-subventricular zone (V-SVZ) presents the highest neurogenic potential in the brain of the adult individual. In rodents, it is mainly composed of chains of neuroblasts. In humans, it is organized in layers where neuroblasts do not form chains. The aim of this study is to describe the cytoarchitecture of canine V-SVZ (cV-SVZ), to assess its neurogenic potential, and to compare our results with those previously described in other species. We have studied by histology, immunohistochemistry (IHC), electron microscopy and neurosphere assay the morphology, cytoarchitecture and neurogenic potential of cV-SVZ. Age groups of animals were performed. Histological and ultrastructural studies indicated that the cV-SVZ is organized in layers as in humans, but including migratory chains as in rodents. Neural progenitors were organized in niches in the subependymal area and a decline in their number was observed with age. Adult-young dogs contained migratory cells capable to expand and differentiate in vitro according with previous results obtained in rodents, primates, humans, pigs, and dogs. Some adult animals presented perivascular niches outside the V-SVZ. Our observations evidence a great similarity between canine and human V-SVZ indicating that the dog may be better representative of neurogenic events in humans, compared with rodents. Accordingly with our results, we conclude that dogs are a valuable animal model of adult neurogenesis in comparative and preclinical studies.

A retrospective study comparing histopathological and immunopathological features of nasal planum dermatitis in 20 dogs with discoid lupus erythematosus or leishmaniosis.

BACKGROUND: In areas endemic for leishmaniosis, discoid lupus erythematosus (DLE) and canine leishmaniosis (CanL) are the most common differential diagnoses for nasal planum erosive-ulcerative dermatitis in dogs. HYPOTHESIS/OBJECTIVE: To compare histopathological and immunopathological features of canine nasal planum erosive-ulcerative dermatitis with depigmentation due to DLE or CanL. ANIMALS: Nasal planum biopsies from dogs with nasal planum loss of architecture, depigmentation, swelling, erosions or ulcerations due to DLE (n = 14) or CanL (n = 6). METHODS: Sections of paraffin-embedded samples, stained with haematoxylin and eosin were reviewed. Samples were examined using antibodies targeting T cells (CD3), B cells (CD20), macrophages (Mac387) and class II major histocompatibility complex (MHC II). Histopathological and immunophenotypical findings were compared between DLE and CanL cases. RESULTS: Lichenoid and interface dermatitis were observed in both DLE and CanL cases. A nodular-to-diffuse, superficial and/or deep dermatitis with macrophages, lymphocytes and plasma cells was present only in CanL samples. CD20-positive cells predominated over CD3- and Mac387-positive cells in the two conditions. The percentage of dermal Mac387-positive cells was higher in CanL compared to DLE samples and the difference was statistically significant (P = 0.025). CONCLUSIONS/CLINICAL IMPORTANCE: In this study, similar histopathological and immunopathological findings were observed in dogs with nasal planum lesions due to DLE or CanL. Therefore, in areas endemic for leishmaniosis, the presence of the parasite should be investigated in canine nasal planum dermatitis showing clinical and histopathological features suggestive of DLE.

miRNA-1 and miRNA-133a are involved in early commitment of pluripotent stem cells and demonstrate antagonistic roles in the regulation of cardiac differentiation.

miRNA-1 (miR-1) and miRNA-133a (miR-133a) are muscle-specific miRNAs that play an important role in heart development and physiopathology. Although both miRNAs have been broadly studied during cardiogenesis, the mechanisms by which miR-1 and miR-133a could influence linage commitment in pluripotent stem cells remain poorly characterized. In this study we analysed the regulation of miR-1 and miR-133a expression during pluripotent stem cell differentiation [P19.CL6 cells; embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs)] and investigated their role in DMSO and embryoid body (EB)-mediated mesodermal and cardiac differentiation by gain- and loss-of-function studies, as well as in vivo, by the induction of teratomas. Gene expression analysis revealed that miR-1 and miR-133a are upregulated during cardiac differentiation of P19.CL6 cells, and also during ESC and iPSC EB differentiation. Forced overexpression of both miRNAs promoted mesodermal commitment and a concomitant decrease in the expression of neural differentiation markers. Moreover, overexpression of miR-1 enhanced the cardiac differentiation of P19.CL6, while miR-133a reduced it with respect to control cells. Teratoma formation experiments with P19.CL6 cells confirmed the influence of miR-1 and miR-133a during in vivo differentiation. Finally, inhibition of both miRNAs during P19.CL6 cardiac differentiation had opposite results to their overexpression. In conclusion, gene regulation involving miR-1 and miR-133a controls the mesodermal and cardiac fate of pluripotent stem cells. Copyright © 2014 John Wiley & Sons, Ltd.

Effects of sphingolipid extracts on the morphological structure and lipid profile in an in vitro model of canine skin.

Ceramides (CER) are essential sphingolipids of the stratum corneum (SC) that play an important role in maintaining cutaneous barrier function. Skin barrier defects occur in both human beings and dogs affected with atopic dermatitis, and have been associated with decreased CER concentrations and morphological alterations in the SC. The aim of the present study was to investigate the changes induced by three different sphingolipid extracts (SPE-1, SPE-2 and SPE-3) on the morphological structure and lipid composition of canine skin, using an in vitro model, whereby keratinocytes were seeded onto fibroblast-embedded collagen type I matrix at the air-liquid interface. Cell cultures were supplemented with SPE-1, SPE-2, SPE-3 or vehicle (control) for 14 days. The relative concentrations of lipids were determined by ultra-performance liquid chromatography coupled to mass spectrometry. The ultrastructural morphology of samples was examined by transmission electron microscopy. SPE-1 induced significant elevation in total CERs, CER[NS], CER[NDS], CER[NP], CER[AS], CER[AP], CER[EOS] and CER[EOP] subclasses, whereas SPE-2 induced a significant elevation in total CER, CER[AP] and CER[EOS] compared with control conditions. Ultrastructural analysis revealed an increase in lamellar-lipid structures in the SC of SPE-1-treated samples. The findings demonstrated that SPE-1 stimulates production of CERs, as shown by changes in lipid composition and ultrastructural morphology. Thus, SPE-1 contributes to the formation of a well-organised SC and represents a potential therapeutic target for improving skin barrier function in atopic dermatitis.

Presence of neural progenitors in spontaneous canine gliomas: A histopathological and immunohistochemical study of 20 cases.

Gliomas are the most common primary brain tumours in humans and are associated with a poor prognosis. An accurate animal model of human glioma tumorigenesis is needed to test new treatment strategies. Dogs represent a promising model because they develop spontaneous diffusely-infiltrating gliomas. This study investigated whether spontaneous canine gliomas contain cancer stem cells previously identified in all grades of human gliomas. Twenty spontaneous cases of canine gliomas were graded according to the human WHO classification. The expression of different markers of lineage differentiation was evaluated with immunohistochemistry as follows: nestin and CD133 for neural stem cells, doublecortin for neuronal progenitor cells, Olig2 for glial progenitor cells, glial fibrillary acidic protein, vimentin and S-100 for mature glial cells, and NeuN and ßIII-tubulin for mature neurons. Gliomas were characterised as follows: five grade II (oligodendrogliomas); nine grade III (seven anaplastic oligodendrogliomas, one anaplastic astrocytoma, one anaplastic oligoastrocytoma); six grade IV (glioblastomas). Immunohistochemical evaluation revealed that (1) nestin and CD133 were expressed in all grades of gliomas with a higher proportion of positive cells in high-grade gliomas; (2) the expression of S-100 protein and Olig2 did not differ substantially between astrocytic and oligodendroglial tumours, and (3) all gliomas were negative for mature neuron markers. The results demonstrated the presence of undifferentiated neural progenitors in all grades of spontaneous canine gliomas, confirming the relevance of this animal model for further studies on cancer stem cells.

Transgenic Mouse Bioassay: Evidence That Rabbits Are Susceptible to a Variety of Prion Isolates.

Interspecies transmission of prions is a well-established phenomenon, both experimentally and under field conditions. Upon passage through new hosts, prion strains have proven their capacity to change their properties and this is a source of strain diversity which needs to be considered when assessing the potential risks associated with consumption of prion contaminated protein sources. Rabbits were considered for decades to be a prion resistant species until proven otherwise recently. To determine the extent of rabbit susceptibility to prions and to assess the effects of passage of different prion strains through this species a transgenic mouse model overexpressing rabbit PrPC was developed (TgRab). Intracerebral challenges with prion strains originating from a variety of species including field isolates (ovine SSBP/1 scrapie, Nor98- scrapie; cattle BSE, BSE-L and cervid CWD), experimental murine strains (ME7 and RML) and experimentally obtained ruminant (sheepBSE) and rabbit (de novo NZW) strains were performed. On first passage TgRab were susceptible to the majority of prions (Cattle BSE, SheepBSE, BSE-L, de novo NZW, ME7 and RML) tested with the exception of SSBP/1 scrapie, CWD and Nor98 scrapie. Furthermore, TgRab were capable of propagating strain-specific features such as differences in incubation periods, histological brain lesions, abnormal prion (PrPd) deposition profiles and proteinase-K (PK) resistant western blotting band patterns. Our results confirm previous studies proving that rabbits are not resistant to prion infection and show for the first time that rabbits are susceptible to PrPd originating in a number of other species. This should be taken into account when choosing protein sources to feed rabbits.

Development and characterization of an equine skin-equivalent model.

BACKGROUND: There is increasing interest in the biological and pathological study of equine skin owing to the high prevalence of cutaneous diseases in horses. However, knowledge of equine skin cell biology and cultures is limited by the low number of in vitro studies in the literature. HYPOTHESIS/OBJECTIVES: The objective of the study was to develop and characterize an in vitro equine skin equivalent. METHODS: Cultures of pure equine keratinocytes and dermal fibroblasts were obtained by enzymatic digestion of skin biopsies. Fibroblasts were embedded into type I collagen matrices to obtain dermal scaffolds, the surface of which was seeded with keratinocytes. The three-dimensional cultures were exposed to the air-liquid interface to enable epidermal stratification. RESULTS: After 14 days in air-exposed conditions, histological analysis showed that keratinocytes underwent differentiation into a multilayered epidermis. Immunohistochemical studies revealed the expression of epidermal cytokeratin in keratinocytes, whereas vimentin was expressed in dermal fibroblasts, as expected in equine skin. Immunostaining of Ki67 showed proliferative keratinocytes in the stratum basale. A continuous basement membrane at the dermo-epidermal junction was also detected immunohistochemically through the expression of its major components (type IV collagen and laminin 5). Ultrastructural analysis by electron microscopy showed desmosomes located among keratinocytes in all layers and hemidesmosomes among the basal keratinocytes and lamina densa. CONCLUSIONS AND CLINICAL IMPORTANCE: This study reports, for the first time, the development of an in vitro equine skin-equivalent model that resembles equine skin morphologically, immunohistochemically and ultrastructurally.

Exploring the risks of a putative transmission of BSE to new species.

The prion responsible for the Bovine Spongiform Encephalopathy (BSE) shows unique features when compared with other prions. One of these features is its ability to infect almost all experimentally tested animal models. In the paper published in The Journal of Neuroscience (1) we describe a series of experiments directed toward elucidating which would be the in vivo behavior of BSE if it would infect dogs and rabbits, two alleged prion resistant species. Protein misfolding cyclic amplification (PMCA) was used to generate canidae and leporidae in vitro adapted BSE prions. A characterization of their in vivo pathobiological properties showed that BSE prions were capable not only of adapting to new species but they maintained, in the case of rabbits, their ability to infect transgenic mice expressing human PrP. The remarkable adaptation ability of certain prions implies that any new host species could lead to the emergence of new infectious agents with unpredictable transmission potential. Our results suggest that caution must be taken when considering the use of any mammal derived protein in feedstuffs.

Bovine spongiform encephalopathy induces misfolding of alleged prion-resistant species cellular prion protein without altering its pathobiological features.

Bovine spongiform encephalopathy (BSE) prions were responsible for an unforeseen epizootic in cattle which had a vast social, economic, and public health impact. This was primarily because BSE prions were found to be transmissible to humans. Other species were also susceptible to BSE either by natural infection (e.g., felids, caprids) or in experimental settings (e.g., sheep, mice). However, certain species closely related to humans, such as canids and leporids, were apparently resistant to BSE. In vitro prion amplification techniques (saPMCA) were used to successfully misfold the cellular prion protein (PrP(c)) of these allegedly resistant species into a BSE-type prion protein. The biochemical and biological properties of the new prions generated in vitro after seeding rabbit and dog brain homogenates with classical BSE were studied. Pathobiological features of the resultant prion strains were determined after their inoculation into transgenic mice expressing bovine and human PrP(C). Strain characteristics of the in vitro-adapted rabbit and dog BSE agent remained invariable with respect to the original cattle BSE prion, suggesting that the naturally low susceptibility of rabbits and dogs to prion infections should not alter their zoonotic potential if these animals became infected with BSE. This study provides a sound basis for risk assessment regarding prion diseases in purportedly resistant species.

Radiofrequency is a secure and effective method for pancreatic transection in laparoscopic distal pancreatectomy: results of a randomized, controlled trial in an experimental model.

BACKGROUND: Postoperative pancreatic fistula (PPF) is the most frequent and serious complication after laparoscopic distal pancreatectomy (LDP). Our goal was to compare the performance, in terms of PPF prevention, and safety of a radiofrequency (RF)-assisted transection device versus a stapler device in a porcine LDP model. METHODS: Thirty-two animals were randomly divided into two groups to perform LDP using a RF-assisted device (RF group; n = 16) and stapler device (ST group; n = 16) and necropsied 4 weeks after surgery. The primary endpoint was the incidence of PPF. Secondary endpoints were surgery/transection time, intra/postoperative complications/deaths, postoperative plasmatic amylase and glucose concentration, peritoneal liquid amylase and interleukin 6 (IL-6) concentrations, weight variations, and histopathological changes. RESULTS: Two clinical and one biochemical PPF were observed in the ST and RF groups respectively. Peritoneal amylase concentration was significantly higher in the RF group 4 days after surgery, but this difference was no longer present at necropsy. Both groups presented a significant decrease in peritoneal IL-6 concentration during the postoperative follow-up, with no differences between the groups. RF group animals showed a higher postoperative weight gain. In the histopathological exam, all RF group animals showed a common pattern of central coagulative necrosis of the parenchymal surface, surrounded by a thick fibrosis, which sealed main and secondary pancreatic ducts and was not found in ST group. CONCLUSIONS: The fibrosis caused by an RF-assisted device can be at least as safe and effective as stapler compression to achieve pancreatic parenchyma sealing in a porcine LDP model.

The tumor suppressor SirT2 regulates cell cycle progression and genome stability by modulating the mitotic deposition of H4K20 methylation.

The establishment of the epigenetic mark H4K20me1 (monomethylation of H4K20) by PR-Set7 during G2/M directly impacts S-phase progression and genome stability. However, the mechanisms involved in the regulation of this event are not well understood. Here we show that SirT2 regulates H4K20me1 deposition through the deacetylation of H4K16Ac (acetylation of H4K16) and determines the levels of H4K20me2/3 throughout the cell cycle. SirT2 binds and deacetylates PR-Set7 at K90, modulating its chromatin localization. Consistently, SirT2 depletion significantly reduces PR-Set7 chromatin levels, alters the size and number of PR-Set7 foci, and decreases the overall mitotic deposition of H4K20me1. Upon stress, the interaction between SirT2 and PR-Set7 increases along with the H4K20me1 levels, suggesting a novel mitotic checkpoint mechanism. SirT2 loss in mice induces significant defects associated with defective H4K20me1-3 levels. Accordingly, SirT2-deficient animals exhibit genomic instability and chromosomal aberrations and are prone to tumorigenesis. Our studies suggest that the dynamic cross-talk between the environment and the genome during mitosis determines the fate of the subsequent cell cycle.

Leishmania amastigotes in the central nervous system of a naturally infected dog.

A 4-year-old male Labrador Retriever dog was presented with a 10-day history of tetraplegia, depression, and absent postural reflexes. The cerebrospinal fluid was positive for Leishmania spp. DNA. At necropsy, a 2-cm long mass was observed adhered to C(7) and C(8) left spinal nerves. Microscopically, nerve fiber destruction together with mixed inflammatory infiltration was observed in the spinal nerves. Cervical spinal cord sections showed multifocal, diffuse granulomatous inflammation in the white matter. In the brain, perivascular infiltrates were observed in some areas together with subtle pallor of the parenchyma. Immunohistochemistry for Leishmania infantum confirmed the presence of amastigotes in the spinal nerves, spinal cord, brain parenchyma, and choroid plexuses. The current study describes the presence of Leishmania amastigotes in nervous tissue inciting radiculoneuritis, myelitis, and mild meningoencephalitis, suggesting a likely route by which L. infantum amastigotes reach and affect the central nervous system parenchyma.