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.

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.

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.

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.

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.

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.

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.

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.

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.

Increased HAS2-driven hyaluronic acid synthesis in shar-pei dogs with hereditary cutaneous hyaluronosis (mucinosis).

The Chinese shar-pei dog is known for its distinctive feature of wrinkled and thickened skin, defined as primary or hereditary cutaneous mucinosis. In a recent report, we identified the mucinous material deposited in the shar-pei skin as the polysaccharide hyaluronan (HA). In the present work, the molecular and cellular mechanisms underlying this phenotype have been identified in dermal fibroblasts isolated from shar-pei dogs. The production of HA, which appeared to be mainly associated with cell membrane protrusions and also intracellular, was higher in shar-pei fibroblasts than in control cells. The HA accumulation is related to a higher mRNA expression of the isoform HAS2 of the HA-synthesizing enzyme family, hyaluronan synthases (HAS). The higher expression of HAS2 in shar-pei fibroblasts was confirmed at the protein level. The other HAS isoenzymes, HAS1 and HAS3, and the HA-degrading enzymes, Hyal1 and Hyal2, were not differentially expressed in shar-pei fibroblasts compared with cells from control dogs. Fibroblasts from shar-pei dogs and from control dogs are morphologically different as observed by transmission electron microscopy. Scanning electron microscopy revealed a large number of cellular protrusions with associated globular deposits. Electron microscopy after labelling with biotinylated HA-binding protein confirmed an increased HA content in shar-pei fibroblasts, which could be localized in several subcellular structures. The authors propose the name hereditary cutaneous hyaluronosis (HCH) for affected dogs, because it better defines the cutaneous mucinosis of shar-pei dogs.

Diabetic neuropathy: electrophysiological and morphological study of peripheral nerve degeneration and regeneration in transgenic mice that express IFNbeta in beta cells.

Diabetic neuropathy is one of the most frequent complications in diabetes but there are no treatments beyond glucose control, due in part to the lack of an appropriate animal model to assess an effective therapy. This study was undertaken to characterize the degenerative and regenerative responses of peripheral nerves after induced sciatic nerve damage in transgenic rat insulin I promoter / human interferon beta (RIP/IFNbeta) mice made diabetic with a low dose of streptozotocin (STZ) as an animal model of diabetic complications. In vivo, histological and immunohistological studies of cutaneous and sciatic nerves were performed after left sciatic crush. Functional tests, cutaneous innervation, and sciatic nerve evaluation showed pronounced neurological reduction in all groups 2 weeks after crush. All animals showed a gradual recovery but this was markedly slower in diabetic animals in comparison with normoglycemic animals. The delay in regeneration in diabetic RIP/IFNbeta mice resulted in an increase in active Schwann cells and regenerating neurites 8 weeks after surgery. These findings indicate that diabetic-RIP/IFNbeta animals mimic human diabetic neuropathy. Moreover, when these animals are submitted to nerve crush they have substantial deficits in nerve regrowth, similar to that observed in diabetic patients. When wildtype animals were treated with the same dose of STZ, no differences were observed with respect to nontreated animals, indicating that low doses of STZ and the transgene are not implicated in development of the degenerative and regenerative events observed in our study. All these findings indicate that RIP/IFNbeta transgenic mice are a good model for diabetic neuropathy.

Detection of Leishmania spp. and associated inflammation in ocular-associated smooth and striated muscles in dogs with patent leishmaniosis.

OBJECTIVE: Canine leishmaniosis is a disease characterized by the wide distribution of the parasite throughout the tissues of the host. The purpose of this study was to describe the presence of Leishmania spp. and associated inflammation in ocular-associated muscles of dogs with patent leishmaniosis. PROCEDURES: Smooth muscles (iris dilator muscle, iris sphincter muscle, ciliary muscle, Müller muscle, smooth muscle of the periorbita and smooth muscle of the nictitating membrane) and striated muscles (orbicularis oculi muscle, obliquus dorsalis muscle and dorsal rectus muscle) were evaluated. Routine staining with hematoxylin and eosin and immunohistochemistry to detect Leishmania spp. were performed on tissue sections. RESULTS: Granulomatous inflammation was seen surrounding muscular fibers and was composed mainly of macrophages with scattered lymphocytes and plasma cells. This infiltrate could be seen in 52/473 (10.99%) samples of smooth muscle and 36/142 (25.35%) samples of striated muscle. Parasites were detected in 43/473 (9.09%) samples of smooth muscle and in 28/142 (19.71%) samples of striated muscle. CONCLUSIONS: To the authors' knowledge, this is the first report assessing the presence of Leishmania spp. and associated infiltrate in intraocular, extraocular and adnexal smooth and striated muscles. The inflammation present in those muscles could contribute to clinical signs already described, such as blepharitis, uveitis, and orbital cellulitis.

Histopathological differences between canine idiopathic sebaceous adenitis and canine leishmaniosis with sebaceous adenitis.

Sebaceous adenitis (SA) may be idiopathic (ISA) or associated with other disorders. The purpose of the present study was to compare the cutaneous histopathology of SA in cases in which Leishmania organisms were detected by immunohistochemistry (IHC) with that of cases diagnosed as ISA. Skin sections of 29 patients were evaluated histologically and divided into two groups, one characterized by several epidermal and subepidermal lesions, a granulomatous to pyogranulomatous nodular to diffuse dermatitis involving the sebaceous glands and a positive IHC for Leishmania spp. The other group was characterized by orthokeratotic hyperkeratosis, follicular keratosis with different degrees of pyogranulomatous to granulomatous SA, lack of nodular dermatitis and a negative IHC for Leishmania spp. Hidradenitis was present in both groups. From these results it can be concluded that SA in canine Leishmaniosis (CL) is usually present together with a nodular to diffuse dermal infiltrate and epidermal and subepidermal lesions, and that SA in the absence of dermal inflammation is probably not associated with or suggestive of CL, even in regions where the disease is endemic.

Hereditary cutaneous mucinosis in shar pei dogs is associated with increased hyaluronan synthase-2 mRNA transcription by cultured dermal fibroblasts.

Shar pei dogs are known for the distinctive feature of thick, wrinkled skin as a consequence of high dermal mucin content. Excessive dermal deposition of mucinous substance leading to severe skin folding, and/or to the more severe vesicular form characterized by dermal vesicles or bullae, is highly prevalent in this breed and is known as idiopathic mucinosis. Hyaluronic acid (HA) is the main component that accumulates in the dermis, and high levels of HA have also been detected in the serum of shar pei dogs. In this study, the cellular and molecular mechanisms underlying cutaneous mucinosis of shar pei dogs were investigated. Thirteen shar pei dogs and four control dogs of other breeds were included. In primary dermal fibroblast cultures, transcription of the family of hyaluronan synthases (HAS) involved in HA synthesis, and of hyaluronidases (HYAL) involved in HA degradation, were studied by reverse transcriptase polymerase chain reaction. The location of HA in cell cultures was studied by immunofluorescence and confocal laser microscopy. Dermal fibroblasts transcribed HAS2, HAS3, HYAL1 and HYAL2, but no amplification for HAS1 was found. A higher transcription of HAS2 was demonstrated in shar pei dogs compared with control dogs. By confocal microscopy, HA was detected as a more diffuse and intense network-like pattern of green fluorescence in the fibroblast cells of shar pei dogs in comparison with control dogs. Together, these results provide additional evidence that hereditary cutaneous mucinosis in shar pei dogs may be a consequence of over-transcription or increased activity of HAS2.

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.

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.