Loss of Furin in β-Cells Induces an mTORC1-ATF4 Anabolic Pathway That Leads to β-Cell Dysfunction

FURIN is a proprotein convertase (PC) responsible for proteolytic activation of a wide array of precursor proteins within the secretory pathway. It maps to the PRC1 locus, a type 2 diabetes susceptibility locus, but its specific role in pancreatic β-cells is largely unknown. The aim of this study was to determine the role of FURIN in glucose homeostasis. We show that FURIN is highly expressed in human islets, whereas PCs that potentially could provide redundancy are expressed at considerably lower levels. β-cell-specific Furin knockout (βFurKO) mice are glucose intolerant as a result of smaller islets with lower insulin content and abnormal dense-core secretory granule morphology. mRNA expression analysis and differential proteomics on βFurKO islets revealed activation of activating transcription factor 4 (ATF4), which was mediated by mammalian target of rapamycin C1 (mTORC1). βFurKO cells show impaired cleavage or shedding of vacuolar-type ATPase (V-ATPase) subunits Ac45 and prorenin receptor, respectively, and impaired lysosomal acidification. Blocking V-ATPase pharmacologically in β-cells increased mTORC1 activity, suggesting involvement of the V-ATPase proton pump in the phenotype. Taken together, these results suggest a model of mTORC1-ATF4 hyperactivation and impaired lysosomal acidification in β-cells lacking Furin, causing β-cell dysfunction.

Putative paraneoplastic pemphigus in a dog: clinical and microscopic findings

In this case report, a dog with clinical and histopathological features of paraneoplastic pemphigus is described. A Lhasa apso with severe ulcerative oral and predominant facial skin disease had a thoracic mass histopathologically diagnosed as a thymoma. A concurrent disease-association was suspected. Cytologic examination of the oral lesions provided early clues to the dog’s ulcerative condition.

Necrotizing eosinophilic dermatitis in three dogs

In this paper, necrotizing eosinophilic dermatitis with an acute onset and a rapidly progressive clinical course is reported in three dogs. Early skin lesions were characterized by intensely pruritic, erythematous and firm intact papules and plaques. The lesions enlarged and evolved quickly into coalescing nodular target shaped lesions with central exudation, ulceration and necrosis. The lesion distribution pattern was mainly the neck and the dorsolateral trunk. Oral involvement was observed in one dog. The histopathology was characterized by eosinophilic dermatitis and panniculitis targeting dermal and subcutaneous blood vessels with secondary involvement of hair follicles. While causation remained unproven in these cases, a hypersensitivity reaction to medications or other foreign antigens was suspected.

Equine Allogeneic Chondrogenic Induced Mesenchymal Stem Cells Are an Effective Treatment for Degenerative Joint Disease in Horses

Degenerative joint disease is one of the main causes of equine early retirement from pleasure riding or a performance career. The disease is initially triggered by an abnormal loading of normal cartilage or a normal loading of abnormal cartilage. This primary insult is accompanied with joint inflammation, which leads to further progressive degeneration of the articular cartilage and changes in the surrounding tissues. Therefore, in search for an effective treatment, 75 adult horses with early signs of degenerative fetlock joint disease were enrolled in a randomized, multicenter, double-blinded, and placebo-controlled study. Fifty animals were injected intra-articularly with the investigational veterinary product (IVP) consisting of allogeneic chondrogenic induced mesenchymal stem cells (ciMSCs) with equine allogeneic plasma, and 25 horses were injected with 0.9% NaCl (saline) control product. From week 3 to 18 after treatment, lameness scores (P < 0.001), flexion test responses (P < 0.034), and joint effusion scores (P < 0.001) were remarkably superior in IVP-treated horses. Besides nasal discharge in both treatment groups, no adverse events were observed during the entire study period. On long-term follow-up (1 year), significantly more investigational product-treated horses were working at training level or were returned to their previous level of work (P < 0.001).

An atypical case of pyoderma gangrenosum in a dog

Neutrophilic and ulcerative dermatitis is reported in a mixed breed dog. The condition was considered to be an atypical case of pyoderma gangrenosum. Clinically, it had a more superficial ulceration, a more pronounced pustular component and lacked the characteristic cutaneous pain and tenderness of the lesions. The diagnosis of pyoderma gangrenosum was made as a diagnosis of exclusion. The dog showed an excellent response to treatment with ciclosporin (Cyclavance, Virbac, Leuven, Belgium).

Degenerative granulomatous mural folliculitis and cytotoxic dermatitis in a dog

A variant of degenerative granulomatous mural folliculitis with cytotoxic dermatitis is reported in a dog that presented with multifocal, well-demarcated, annular alopecia with peripheral crusting. The skin condition might have been drug-induced and responded well to oral ciclosporin.

Archival May-Grünwald-Giemsa-Stained Bone Marrow Smears Are an Eligible Source for Molecular DNA Research

Biobanking is increasingly important in studying complex heterogeneous diseases. Therefore, it is essential to ensure the sample quality after long-term storage for reliable downstream analyses. The Clinical Biobank of the Jessa Hospital and the University Biobank Limburg (UBiLim) hold a continuously growing collection of hematological samples, including May-Grünwald-Giemsa (MGG)- and Perls' Prussian Blue (PPB)-stained bone marrow (BM) smears, stored at room temperature (RT) for up to 20 years. In this study, we investigated the effect of short- and long-term storage on the quality of DNA and RNA extracted from these BM smears to assess their fitness-for-purpose in downstream molecular applications, including agarose gel electrophoresis, bio-analyzer analysis, quantitative polymerase chain reaction (qPCR), and targeted next-generation sequencing (NGS). The RNA quality was very low for all samples, independent of storage time or staining method. The DNA from PPB-stained BM smears was already degraded after 1 year of storage and correspondingly could not be used for reliable downstream molecular analysis. In contrast, DNA extracted from MGG-stained BM smears stored for up to 10 years was able to generate high-quality data in qPCR and targeted NGS analyses. Longer storage periods (>15 years) of these samples revealed a high degree of degradation and a significant amount of DNA transitions and transversions. In conclusion, the DNA extracted from archival MGG-stained BM smears with a storage time up to at least 10 years was qualitatively good and fit for downstream analysis, including targeted NGS. This indicates that these samples are an eligible source for molecular DNA research and for studying complex diseases.

Prognostic Biomarkers in the Progression From MGUS to Multiple Myeloma: A Systematic Review

Multiple myeloma (MM), characterized by malignant plasma cells in the bone marrow, is consistently preceded by asymptomatic premalignant stage monoclonal gammopathy of undetermined significance (MGUS). These MGUS patients have an annual risk of 1% to progress to MM. Clinical, imaging, and genomic (genetic and epigenetic) factors were identified, whose presence increased the risk of progression from MGUS to MM. In this systematic review we summarize the currently identified clinical, imaging, and genomic biomarkers suggested to increase the progression risk or shown to be differentially expressed/present between both cohorts of patients. Despite the wide range of proposed markers, there are still no reliable biomarkers to individually predict which MGUS patient will progress to MM and which will not. Research on biomarkers in the progression from MGUS to MM will give more insight in the unknown pathogenesis of this hematological malignancy. This would improve research by elucidating new pathways and potential therapeutic targets as well as clinical management by closer follow-up and earlier treatment of high-risk MGUS patients.

Surgical repair of a tibial fracture in a Belgian Landrace pig

This paper reports the surgical treatment of a tibial fracture in a castrated adult male Belgian Landrace pig of 180 kg. The fracture was repaired using an intramedullary Steinmann pin, combined with cerclage wire and external transfixation. In contrast to other animal species, the fracture repair in the pig was hindered by the short and curved bones, the thick subcutaneous fat layer and the pronounced musculature. Postoperatively, the pig developed an osteomyelitis of the tibia due to pin tract contamination. Despite this complication, the fracture healed acceptably when all fixation material was removed two months after surgery. The infection resolved quickly and a satisfactory clinical result was obtained.

Tenogenically Induced Allogeneic Peripheral Blood Mesenchymal Stem Cells in Allogeneic Platelet-Rich Plasma: 2-Year Follow-up after Tendon or Ligament Treatment in Horses

Poor healing of tendon and ligament lesions often results in early retirement of sport horses. Therefore, regenerative therapies are being explored as potentially promising treatment for these injuries. In this study, an intralesional injection was performed with allogeneic tenogenically induced mesenchymal stem cells and platelet-rich plasma 5-6 days after diagnosis of suspensory ligament (SL) (n = 68) or superficial digital flexor tendon (SDFT) (n = 36) lesion. Clinical, lameness and ultrasonographic evaluation was performed at 6 and 12 weeks. Moreover, a survey was performed 12 and 24 months after treatment to determine how many horses were competing at original level and how many were re-injured. At 6 weeks, 88.2% of SL (n = 68) and 97.3% of SDFT lesions (n = 36) demonstrated moderate ultrasonographic improvement. At 12 weeks, 93.1% of SL (n = 29) and 95.5% of SDFT lesions (n = 22) improved convincingly. Moreover, lameness was abolished in 78.6% of SL (n = 28) and 85.7% (n = 7) of SDFT horses at 12 weeks. After 12 months (n = 92), 11.8% of SL and 12.5% of SDFT horses were re-injured, whereas 83.8 of SL and 79.2% of SDFT returned to previous performance level. At 24 months (n = 89) after treatment, 82.4 (SL) and 85.7% (SDFT) of the horses returned to previous level of performance. A meta-analysis was performed on relevant published evidence evaluating re-injury 24 months after stem cell-based [17.6% of the SL and 14.3% of the SDFT group (n = 89)] versus conventional therapies. Cell therapies resulted in a significantly lower re-injury rate of 18% [95% confidence interval (CI), 0.11-0.25] 2 years after treatment compared to the 44% re-injury rate with conventional treatments (95% CI, 0.37-0.51) based on literature data (P < 0.0001).

From Bone Marrow to Cardiac Atrial Appendage Stem Cells for Cardiac Repair: A Review

Traditionally the heart is considered a terminally differentiated organ. However, at the beginning of this century increased mitotic activity was reported in ischemic and idiopathic dilated cardiomyopathy hearts, compared to healthy controls, underscoring the potential of regeneration after injury. Due to the presence of adult stem cells in bone marrow and their purported ability to differentiate into other cell lineages, this cell population was soon estimated to be the most suited candidate for cardiac regeneration. Clinical trials with autologous bone marrow-derived mononuclear cells, using either an intracoronary or direct intramyocardial injection approach consistently showed only minor improvement in global left ventricular ejection fraction. This was explained by their limited cardiomyogenic differentiation potential. To obtain more convincing improvement in cardiac function, based on true myocardial regeneration, the focus of research has shifted towards resident cardiac progenitor cells. Several isolation procedures have been described: the c-kit surface marker was the first to be used, however experimental research has clearly shown that c-kit+ cells only marginally contribute to regeneration post myocardial infarction. Sphere formation was used to isolate the so-called cardiosphere derived cells (CDC), and also in this cell population cardiomyogenic differentiation is a rare event. Recently a new type of stem cells derived from atrial tissue (cardiac atrial stem cells - CASCs) was identified, based on the presence of the enzyme aldehyde dehydrogenase (ALDH). Those cells significantly improve both regional and global LV ejection fraction, based on substantial engraftment and consistent differentiation into mature cardiomyocytes (98%).

Cardiac atrial appendage stem cells promote angiogenesis in vitro and in vivo

Cardiac atrial appendage stem cells (CASCs) show extraordinary myocardial differentiation properties, making them ideal candidates for myocardial regeneration. However, since the myocardium is a highly vascularized tissue, revascularization of the ischemic infarct area is essential for functional repair. Therefore, this study assessed if CASCs contribute to cardiac angiogenesis via paracrine mechanisms. First, it was demonstrated that CASCs produce and secrete high levels of numerous angiogenic growth factors, including vascular endothelial growth factor (VEGF), endothelin-1 (ET-1) and insulin-like growth factor binding protein 3 (IGFBP-3). Functional in vitro assays with a human microvascular endothelial cell line (HMEC-1) and CASC CM showed that CASCs promote endothelial cell proliferation, migration and tube formation, the most important steps of the angiogenesis process. Addition of inhibitory antibodies against identified growth factors could significantly reduce these effects, indicating their importance in CASC-induced neovascularization. The angiogenic potential of CASCs and CASC CM was also confirmed in a chorioallantoic membrane assay, demonstrating that CASCs promote blood vessel formation in vivo. In conclusion, this study shows that CASCs not only induce myocardial repair by cardiomyogenic differentiation, but also stimulate blood vessel formation by paracrine mechanisms. The angiogenic properties of CASCs further strengthen their therapeutic potential and make them an optimal stem cell source for the treatment of ischemic heart disease.

Nuclear Localization of the Autism Candidate Gene Neurobeachin and Functional Interaction with the NOTCH1 Intracellular Domain Indicate a Role in Regulating Transcription

BACKGROUND

Neurobeachin (NBEA) is an autism spectrum disorders (ASD) candidate gene. NBEA deficiency affects regulated secretion, receptor trafficking, synaptic architecture and protein kinase A (PKA)-mediated phosphorylation. NBEA is a large multidomain scaffolding protein. From N- to C-terminus, NBEA has a concanavalin A-like lectin domain flanked by armadillo repeats (ACA), an A-kinase anchoring protein domain that can bind to PKA, a domain of unknown function (DUF1088) and a BEACH domain, preceded by a pleckstrin homology-like domain and followed by WD40 repeats (PBW). Although most of these domains mediate protein-protein interactions, no interaction screen has yet been performed.

METHODS

Yeast two-hybrid screens with the ACA and PBW domain modules of NBEA gave a list of interaction partners, which were analyzed for Gene Ontology (GO) enrichment. Neuro-2a cells were used for confocal microscopy and nuclear extraction analysis. NOTCH-mediated transcription was studied with luciferase reporter assays and qRT-PCR, combined with NBEA knockdown or overexpression.

RESULTS

Both domain modules showed a GO enrichment for the nucleus. PBW almost exclusively interacted with transcription regulators, while ACA interacted with a number of PKA substrates. NBEA was partially localized in the nucleus of Neuro-2a cells, albeit much less than in the cytoplasm. A nuclear localization signal was found in the DUF1088 domain, which was shown to contribute to the nuclear localization of an EGFP-DPBW fusion protein. Yeast two-hybrid identified the Notch1 intracellular domain as a physical interactor of the PBW domain and a role for NBEA as a negative regulator in Notch-mediated transcription was demonstrated.

CONCLUSION

Defining novel interaction partners of conserved NBEA domain modules identified a role for NBEA as transcriptional regulator in the nucleus. The physical interaction of NBEA with NOTCH1 is most relevant for ASD pathogenesis because NOTCH signaling is essential for neural development.

Endoplasmic reticulum-associated degradation of the mouse PC1/3-N222D hypomorph and human PCSK1 mutations contributes to obesity

BACKGROUND

The proprotein convertase 1/3 (PC1/3), encoded by proprotein convertase subtilisin/kexin type 1 (PCSK1), cleaves and hence activates several orexigenic and anorexigenic proproteins. Congenital inactivation of PCSK1 leads to obesity in human but not in mice. However, a mouse model harboring the hypomorphic mutation N222D is obese. It is not clear why the mouse models differ in phenotype.

METHODS

Gene expression analysis was performed with pancreatic islets from Pcsk1(N222D/N222D) mice. Subsequently, biosynthesis, maturation, degradation and activity were studied in islets, pituitary, hypothalamus and cell lines. Coimmunoprecipitation of PC1/3-N222D and human PC1/3 variants associated with obesity with the endoplasmic reticulum (ER) chaperone BiP was studied in cell lines.

RESULTS

Gene expression analysis of islets of Pcsk1(N222D/N222D) mice showed enrichment of gene sets related to the proteasome and the unfolded protein response. Steady-state levels of PC1/3-N222D and in particular the carboxy-terminally processed form were strongly reduced in islets, pituitary and hypothalamus. However, impairment of substrate cleavage was tissue dependent. Proinsulin processing was drastically reduced, while processing of proopiomelanocortin (POMC) to adrenocorticotropic hormone (ACTH) in pituitary was only mildly impaired. Growth hormone expression and IGF-1 levels were normal, indicating near-normal processing of hypothalamic proGHRH. PC1/3-N222D binds to BiP and is rapidly degraded by the proteasome. Analysis of human PC1/3 obesity-associated mutations showed increased binding to BiP and prolonged intracellular retention for all investigated mutations, in particular for PC1/3-T175M, PC1/3-G226R and PC1/3-G593R.

CONCLUSIONS

This study demonstrates that the hypomorphic mutation in Pcsk1(N222D) mice has an effect on catalytic activity in pancreatic islets, pituitary and hypothalamus. Reduced substrate processing activity in Pcsk1(N222D/N222D) mice is due to enhanced degradation in addition to reduced catalytic activity of the mutant. PC1/3-N222D binds to BiP, suggesting impaired folding and reduced stability. Enhanced BiP binding is also observed in several human obesity-associated PC1/3 variants, suggesting a common mechanism.

Metabolic and Behavioural Phenotypes in Nestin-Cre Mice Are Caused by Hypothalamic Expression of Human Growth Hormone

The Nestin-Cre driver mouse line has mild hypopituitarism, reduced body weight, a metabolic phenotype and reduced anxiety. Although several causes have been suggested, a comprehensive explanation is still lacking. In this study we examined the molecular mechanisms leading to this compound phenotype. Upon generation of the Nestin-Cre mice, the human growth hormone (hGH) minigene was inserted downstream of the Cre recombinase to ensure efficient transgene expression. As a result, hGH is expressed in the hypothalamus. This results in the auto/paracrine activation of the GH receptor as demonstrated by the increased phosphorylation of signal transducer and activator of transcription 5 (STAT5) and reduced expression of growth hormone releasing hormone (Ghrh). Low Ghrh levels cause hypopituitarism consistent with the observed mouse growth hormone (mGH) deficiency. mGH deficiency caused reduced activation of the GH receptor and hence reduced phosphorylation of STAT5 in the liver. This led to decreased levels of hepatic Igf-1 mRNA and consequently postnatal growth retardation. Furthermore, genes involved in lipid uptake and synthesis, such as CD36 and very low-density lipoprotein receptor were upregulated, resulting in liver steatosis. In conclusion, this study demonstrates the unexpected expression of hGH in the hypothalamus of Nestin-Cre mice which is able to activate both the GH receptor and the prolactin receptor. Increased hypothalamic GH receptor signaling explains the observed hypopituitarism, reduced growth and metabolic phenotype of Nestin-Cre mice. Activation of either receptor is consistent with reduced anxiety.

A case of pyoderma gangrenosum in a dog successfully treated with prednisolone alone

In this case report, a markedly painful ulcerative dermatitis consistent with pyoderma granulosum is reported in a 2.5-year-old entire female Maltese dog. The dog had a nasal stridor and irregular ulcers with raised inflammatory borders involving the lumbar area, tail and the hindlimbs. The lesions did not respond to antibiotics. Histopathologic features include deep crateriform ulcerations with massive infiltrations of neutrophils beneath and adjacent to the ulcers. Treatment with prednisolone (Kela Laboratories, Sint-Niklaas, Belgium) alone resulted in the resolution of nasal signs and all skin lesions.

Canine recurrent flank alopecia: a synthesis of theory and practice

Canine recurrent flank alopecia is a non-inflammatory, non-scarring alopecia of unknown etiology and has a visually striking clinical presentation. Although this disease entity is relatively common in the northern hemisphere, there is only scant information in the literature regarding case descriptions. The aim of this article was to review the literature and to describe clinical presentations recognized in practice, which are not always extensively documented in the literature.

Impaired islet function in commonly used transgenic mouse lines due to human growth hormone minigene expression

The human growth hormone (hGH) minigene is frequently used in the derivation of transgenic mouse lines to enhance transgene expression. Although this minigene is present in the transgenes as a secondcistron, and thus not thought to be expressed, we found that three commonly used lines, Pdx1-Cre(Late), RIP-Cre, and MIP-GFP, each expressed significant amounts of hGH in pancreatic islets. Locally secreted hGH binds to prolactin receptors on β cells, activates STAT5 signaling, and induces pregnancy-like changes in gene expression, thereby augmenting pancreatic β cell mass and insulin content. In addition, islets of Pdx1-Cre(Late) mice have lower GLUT2 expression and reduced glucose-induced insulin release and are protected against the β cell toxin streptozotocin. These findings may be important when interpreting results obtained when these and other hGH minigene-containing transgenic mice are used.

Vraag & Antwoord

Fibroadenomateuze melkklierhyperplasie bij de kat Behandeling van mycetoma bij de kat Behandeling van retentio secundarum bij het rund

Perforerende dermatitis bij een kat

Een 8,5 maanden oude, gecastreerde kater werd aangeboden met een jeukend lineair letsel aan de rechterachterpoot dat zich uitstrekte van caudomediaal van de tarsus tot ventraal van de staartbasis. Het letsel bestond uit multipele, dikke, conische, geelbruine korsten en alopecie. Op een afdrukpreparaat waren talrijke eosinofielen en enkele mastcellen zichtbaar. Het histopathologisch onderzoek van huidbiopten toonde het typische beeld van perforerende dermatitis met verticaal georiënteerde collageenvezels en eosinofiele dermatitis. Een behandeling met dexamethason gaf lichte verbetering. Wanneer dexamethason gecombineerd werd met een topicale mometasontherapie verdwenen de letsels volledig.

Phlorizin pretreatment reduces acute renal toxicity in a mouse model for diabetic nephropathy

Streptozotocin (STZ) is widely used as diabetogenic agent in animal models for diabetic nephropathy (DN). However, it is also directly cytotoxic to kidneys, making it difficult to distinguish between DN-related and STZ-induced nephropathy. Therefore, an improved protocol to generate mice for DN studies, with a quick and robust achievement of the diabetic state, without direct kidney toxicity is required. To investigate the mechanism leading to STZ-induced nephropathy, kidney damage was induced with a high dose of STZ. This resulted in delayed gastric emptying, at least partially caused by impaired desacyl ghrelin clearance. STZ uptake in the kidneys is to a large extent mediated by the sodium/glucose cotransporters (Sglts) because the Sglt inhibitor phlorizin could reduce STZ uptake in the kidneys. Consequently, the direct toxic effects in the kidney and the gastric dilatation were resolved without interfering with the β-cell toxicity. Furthermore, pancreatic STZ uptake was increased, hereby decreasing the threshold for β-cell toxicity, allowing for single low non-nephrotoxic STZ doses (70 mg/kg). In conclusion, this study provides novel insights into the mechanism of STZ toxicity in kidneys and suggests a more efficient regime to induce DN with little or no toxic side effects.

Zic3 enhances the generation of mouse induced pluripotent stem cells

Zinc finger protein of the cerebellum (Zic)3, a member of Gli family of transcription factors (TFs), is essential for maintaining pluripotency of embryonic stem cells (ESCs) and has been reported to activate TF Nanog in an Oct4/Sox2-independent manner. Previously, we showed that Zic3 (Z), in combination with the Yamanka factors OCT4, SOX2, and KLF4 (OSK), induces neural progenitor-like cells from human fibroblasts. However, a similar combination of TFs (OSKZ) transduced in mouse embryonic fibroblasts resulted in enhanced induced pluripotent stem cells (iPSCs) formation compared with OSK alone, but not neuroprogenitors. OSKZ-derived iPSCs are indistinguishable from mESCs in colony morphology, expression of alkaline phosphatase and pluripotency genes, and embryoid body and teratoma formation. Zic3 activates the transcription of Nanog, a key pluripotency regulator, as evidenced by a luciferase promoter assay. During the course of iPSC derivation, Zic3-mediated enhanced expression of Nanog and Tbx3, gene known to enhance iPSCs derivation, is observed. Not only does Zic3 enhance the reprogramming efficiency, but also reactivation of the endogenous Zic3 protein is essential for the generation of iPSCs, as knockdown of Zic3 during the iPSC generation with OSKM significantly reduced the number of colonies. Together, our result uncovers an important role of Zic3 in generating mouse iPSCs.

Unilaterale sino-orbitale en subcutane aspergillose bij een kat

Een jonge kattin werd na een periode van niezen en conjunctivitis aangeboden voor onderhuidse zwellingen op de linkerzijde van de kop en hyperemische conjunctiva met protrusie van het derde ooglid. Het onderzoek van de mondholte toonde een zwelling aan labiaal van de gebitselementen en in de pterygopalatine fossa. De linker submandibulaire lymfeknoop was opgezet. De kat niesde af en toe maar er was geen neusvloei. De huidletsels hadden een opvallende gele kleur. Het cytologisch onderzoek van de huidzwelling toonde een pyogranulomateuze ontsteking aan met eosinofielen. Alleen een diepe bemonstering bevatte representatief weefsel voor cytologisch, histopathologisch en mycologisch onderzoek. Op basis van de morfologische kenmerken van de mycologische cultuur werd Aspergillus sectie fumigatus gediagnosticeerd en met moleculaire technologie geïdentificeerd als Aspergillus viridinutans. De definitieve diagnose was sino-orbitale aspergillose met een uitgebreide subcutane invasie. Gezien het ernstig progressief verloop ondanks behandeling werd de kat geëuthanaseerd.

The histological appearance of the proximal aspect of the dorsal condylar sagittal ridge of the third metacarpal and metatarsal bone in young warmblood horses: normal appearance and correlation with detected radiographic variations

The objective of this study is to describe the normal histological appearance of the dorsoproximal aspect of the sagittal ridge of the third metacarpal/metatarsal bone in young Warmblood horses, and to compare it to the different radiographic variations (irregular, indentation, lucency, notch) described at this level. A total of 25 metacarpo/metatarsophalangeal joints of 12 Warmblood horses were used. Five samples of each radiographically described group were selected for histological processing. Each category was compared with the normal control group. Each group showed a bone cortex, covered by hyaline cartilage and longitudinally aligned collagen fibres covered by loosely organized connective tissue proximally. The normal and irregular group showed a smooth bone cortex. In the indentation and lucency group, a depression in the cortex was detected. The notch group presented an expansion of the cortex. The collagen fibres and connective tissue were located in the depression in the indentation group whereas the location varied in the lucency and notch group. The radiologic detected differences are translated into detectable histological differences. Further research is warranted to determine whether these variations are developmental or congenital and to evaluate their potential influence on the joint function during hyperextension.

Tongue and tail necrosis in an atypical case of acute steroid responsive meningitis-arteritis in a dog

Acute steroid responsive meningitis-arteritis (SRMA) is a common neurological disorder in young dogs. Typical clinical symptoms of the acute form of SRMA are neck pain, depression and fever. This case report describes a 1.5-year-old Pointer with uncommon neurological deficits (unilateral multiple cranial nerve deficits and Horner’s syndrome) and an exceptional necrosis of the tongue. This was believed to be part of the systemic vasculitis accompanying SRMA. The patient also developed tail necrosis and iatrogenic calcinosis cutis, which complicated further treatment of the dog.

Abstract 4627: Generation and characterization of non-competitive furin-inhibiting nanobodies

Furin belongs to a family of seven closely related subtilisin-like serine endoproteases, known as proprotein convertases (PCs), PC1/3, PC2, PC4, PC5/6, PACE4 and PC7. The physiological role of furin is to cleave and hence activate a large variety of proproteins. Therefore, it is not surprising that it plays a major role in many pathologies such as cancer and infectious diseases. Furin inhibition might be a good strategy for therapeutic intervention, and several furin inhibitors have been generated, although thus far none are entirely furin-specific. To reduce potential side effects caused by cross-reactivity with other proteases, dromedary heavy chain antibodies against catalytically active furin were developed as specific furin inhibitors. Nanobodies derived from these antibodies bind only to mouse and human furin but not to other PCs. In addition, upon overexpression in cell lines, these nanobodies can inhibit the cleavage of three different furin substrates, TGFβ, BAFF and GPC3. The purified nanobodies can also inhibit the cleavage of diphtheria toxin into its enzymatically active A fragment, but do not inhibit cleavage of a small synthetic peptide-based substrate, suggesting a mode of action based on steric hindrance. The inhibitory constant of the purified nanobodies was shown to be in the micromolar range and the nanobodies are non-competitive inhibitors as demonstrated by Dixon plot. Furthermore, anti-furin nanobodies can protect HEK293T cells from diphtheria toxin-induced cytotoxicity as efficiently as the well characterized PC inhibitor nona-D-arginine. In conclusion, these antibody-based single-chain nanobodies represent the first generation of highly specific, non-competitive furin inhibitors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4627. doi:1538-7445.AM2012-4627

Abstract 1981: Interference of the polyphenolic compound curcumin with expression regulation of target genes of the PLAG1 oncogenic transcription factor

Transcriptional upregulation of a variety of signaling genes is a key feature of PLAG1-induced tumorigenesis. The PLAG1 gene is mainly expressed during embryogenesis and mobilization of its oncogenic potential in human tumors results from genetic aberrations. The oncogenic capacity of the PLAG1 gene was initially demonstrated by various standard experimental approaches in vitro. The oncogenic potential of the PLAG1 gene was further demonstrated by the generation of a versatile tumor mouse model system with Cre-mediated expression activation of the PLAG1 gene. In previous studies, it was demonstrated that the PLAG1-encoded protein is a genuine transcription factor, which recognizes a specific bipartite DNA sequence motif and activates a variety of target genes among which genes of the Igf and Wnt signaling pathways. In an attempt to interfere with the oncogenic PLAG1 transcription factor, the possible effect of a variety of natural products including various polyphenols was studied. Initially, PLAG1 transduced Balb/c-3T3 expressing high levels of PLAG1 were screened for the possible effect of a variety of polyphenols on the PLAG1-induced upregulation of various established PLAG1 target genes such as for instance Igf2. The polyphenolic compound curcumin was selected for further studies since, in the initial experiments, it was shown to exhibit downregulation of Igf2 expression as well as that of other well-established PLAG1 target genes such as H19, Dlk1, and Gtl2. Evaluation of the expression of various genes which lack the PLAG1-specific bipartite DNA binding motif in their promoter regions revealed no effect of curcumin; e.g. Plag1, Wnt6 and Ctnnb1. The observation that preferentially the expression of PLAG1 target genes was affected by curcumin raised the possibility that curcumin might interfere with the binding of the PLAG1 transcription factor to its specific DNA binding sites in the promoter regions of the tested PLAG1 target genes. To test this hypothesis, the effect of curcumin on the expression of two reporter gene constructs was studied. These reporter constructs consisted of the luciferase gene under expression control of a HSK-tk promoter with either three wild-type PLAG1-specific DNA binding motifs or, as a control, three mutated forms of it upstream of HSV-tk. The results of these experiments suggested that curcumin indeed might interfere directly with the binding of the PLAG1 transcription factor protein to its cognate DNA binding motif. To further substantiate these results in an independent way, EMSA experiments are being performed. Altogether, the results of these studies seem to favor the notion that curcumin could directly affect the PLAG1-induced tumorigenic process in vivo by interfering with the binding of the PLAG1 transcription factor to its cognate binding sites in promoter regions of target genes.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1981. doi:1538-7445.AM2012-1981

Internalization of proprotein convertase PC7 from plasma membrane is mediated by a novel motif

Proprotein convertase 7 (PC7) is a member of the subtilisin-like proprotein convertase family, which is involved in the endoproteolysis of a variety of precursor proteins. Under steady state conditions, PC7 is mainly localized in the trans-Golgi network, but a small fraction is found at the cell surface. So far, no sorting signals for membrane trafficking have been identified in PC7. In this study, we have examined the internalization of PC7 from the plasma membrane. Our results show that internalization of PC7 is mediated by clathrin-coated vesicles. After inhibition of clathrin-mediated endocytosis using hypertonic conditions or the small molecule inhibitor, Pitstop 2, PC7 accumulated at the plasma membrane. Furthermore, PC7 was present in isolated clathrin-coated vesicles. To determine the internalization motif, constructs were generated in which parts of the N and C terminus of the cytoplasmic tail of PC7 were deleted, and chimeric proteins were constructed consisting of the luminal and transmembrane domains of Tac (CD25) and parts of the cytoplasmic domain of PC7. Antibody uptake experiments as well as surface biotinylation experiments demonstrated that the region between Ala(713) and Cys(726) in the cytoplasmic domain of PC7 is essential and sufficient for the internalization of PC7 but not for trans-Golgi network localization. Individual amino acids in this region were substituted with alanine, which identified Pro, Leu, and Cys as the essential amino acids. In conclusion, internalization of PC7 depends on a short transferable sequence in the cytoplasmic tail, which contains the three crucial amino acids PLC.

Pdx1- and Ngn3-Cre-mediated PLAG1 expression in the pancreas leads to endocrine hormone imbalances that affect glucose metabolism

Pleomorphic adenoma gene-like 1 (PLAGL1) has been linked to transient neonatal diabetes mellitus. Here, we investigated the role of the related pleomorphic adenoma gene 1 (PLAG1) in glucose homeostasis. PLAG1 transgenic mice in which expression of the PLAG1 transgene can be targeted to different organs by Cre-mediated modulation were crossed with Pdx1-Cre or Ngn3-Cre mice, resulting in double transgenic P1-Pdx1Cre or P1-Ngn3Cre mice, respectively. P1-Pdx1Cre and P1-Ngn3Cre mice developed hyperplasia of pancreatic islets due to increased β- and δ- but not α-cell proliferation. In young P1-Pdx1Cre mice (less than 15 weeks) there was a balanced increase in the pancreatic content of insulin and somatostatin, which was associated with normoglycemia. In older P1-Pdx1Cre mice the pancreatic somatostatin content far exceeded that of insulin, leading to the progressive development of severe hypoglycemia beyond 30 weeks. In contrast, in older P1-Ngn3Cre mice the relative increase of the pancreatic insulin content exceeded that of somatostatin and these mice remained normoglycemic. In conclusion, forced expression of PLAG1 under the control of the Pdx1 or Ngn3 promoter in murine pancreas induces different degrees of endocrine hormone imbalances within the pancreas, which is associated with hypoglycemia in P1-Pdx1Cre mice but not P1-Ngn3Cre mice. These results suggest that once stem cell-derived islet transplantations become possible, the appropriate balance between different hormone-producing cells will need to be preserved to prevent deregulated glucose metabolism.

Increased beta-cell mass by islet transplantation and PLAG1 overexpression causes hyperinsulinemic normoglycemia and hepatic insulin resistance in mice

OBJECTIVE

It is believed that an organism remains normoglycemic despite an increase in the beta-cell mass because of decreased insulin production by beta-cells on a per-cell basis. However, some transgenic mouse models with beta-cell hyperplasia suggest that insulin production remains excessive and that normoglycemia is maintained by insulin resistance.

METHODS

Here, we investigated the effect of an increased beta-cell mass on glycemia and insulin resistance by grafting excess normal islets in normoglycemic mice, as well as using targeted PLAG1 expression in beta-cells, which leads to beta-cell expansion.

RESULTS

In both models, fasting plasma insulin levels were increased, even though animals were normoglycemic. After an intraperitoneal glucose tolerance test, plasma insulin levels increased, which was associated with improved glucose clearing. Under these conditions, normoglycemia is maintained by hepatic insulin resistance as demonstrated by hyperinsulinemic euglycemic clamp experiments.

CONCLUSIONS

In conclusion, we demonstrate that when excess beta-cells are grafted, insulin production on a per beta-cell basis is not sufficiently decreased, leading to hyperinsulinemia and hepatic insulin resistance. This observation might be important for the design of stem cell-based islet replacement therapies.

Abstract 4166: Targeted expression of the Pleomorphic adenoma gene 1 in the pancreas of mice leads to islet hyperplasia

Pleomorphic adenoma gene 1 (PLAG1) encodes a transcription factor that is involved in several human neoplasias such as in pleomorphic adenomas of the salivary glands, lipoblastoma, hepatoblastoma and AML. The oncogenic capacity of PLAG1 has been further demonstrated in vivo in PLAG1 transgenic mice, in which the activation of the PLAG1 expression is Cre-mediated. Targeted expression of PLAG1 in the salivary gland or in the mammary gland leads to pleomorphic adenomas of the salivary glands and adenomyoepitheliomatous lesions of the mammary glands, respectively. Here, we investigated the impact of targeted PLAG1 expression in the pancreas. Pdx1-Cre-mediated targeted expression of PLAG1 in the whole pancreas, leads to islet hyperplasia. Although there was initially a balanced increase in the insulin, somatostatin and glucagon content of the pancreas, in older P1-Pdx1Cre mice the production of insulin and somatostatin far exceeded that of glucagon (82%, 275% and 9% respectively in 1 year old P1-Pdx1Cre mice as compared to littermate Pdx1-Cre mice). This was associated with hyperinsulinemia and an increased ability to dispose glucose in P1-Pdx1Cre mice, and progressive development of severe hypoglycaemia. Only 1/10 one year old mice developed a pancreatic tumor. We also investigated the consequence of overexpression of PLAG1 only in β-cells by using RIP-Cre mice. Similar to P1-Pdx1Cre mice, P1-RIPCre mice displayed islet hyperplasia, hyperinsulinemia and an increased ability to dispose glucose. Nevertheless, in contrast to P1-Pdx1Cre mice, P1-RIPCre mice stay normoglycemic and compensate for the hyperinsulinemia by the development of hepatic insulin resistance. In conclusion our data demonstrates that targeted expression of PLAG1 in the pancreas leads to islet hyperplasia rather than to pancreatic tumor formation.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4166.

Cardiorespiratory effects of enoximone in anaesthetised colic horses

REASONS FOR PERFORMING STUDY

No studies have been reported on the effects of enoximone in anaesthetised colic horses.

OBJECTIVE

To examine whether enoximone improves cardiovascular function and reduces dobutamine requirement in anaesthetised colic horses.

METHODS

Forty-eight mature colic horses were enrolled in this prospective, randomised clinical trial. After sedation (xylazine 0.7 mg/kg bwt) and induction (midazolam 0.06 mg/kg bwt, ketamine 2.2 mg/kg bwt), anaesthesia was maintained with isoflurane in oxygen and a lidocaine constant rate infusion (15 mg/kg bwt, 2 mg/kg/h). Horses were ventilated (PaCO2 < 8.00 kPa). If hypotension occurred, dobutamine and/or colloids were administered. Ten minutes after skin incision, horses randomly received an i.v. bolus of enoximone (0.5 mg/kg bwt) or saline. Monitoring included respiratory and arterial blood gases, heart rate (HR), arterial pressure and cardiac index (CI). Systemic vascular resistance (SVR), stroke index (SI) and oxygen delivery index (DO2I) were calculated. For each variable, changes between baseline and T10 within each treatment group and/or colic type (small intestines, large intestines or mixed) were analysed and compared between treatments in a fixed effects model. Differences between treatments until T30 were investigated using a mixed model (a = 0.05).

RESULTS

Ten minutes after enoximone treatment, CI (P = 0.0010), HR (P = 0.0033) and DO2I (P = 0.0007) were higher and SVR lower (P = 0.0043) than at baseline. The changes in CI, HR and SVR were significantly different from those after saline treatment. During the first 30 min after enoximone treatment, DO2I (P = 0.0224) and HR (P = 0.0003) were higher than after saline administration. Because the difference in HR between treatments was much clearer in large intestine colic cases, an interaction was detected between treatment and colic type in both analyses (P = 0.0076 and 0.0038, respectively).

CONCLUSIONS

Enoximone produced significant, but short lasting, cardiovascular effects in colic horses.

POTENTIAL RELEVANCE

Enoximone's cardiovascular effects in colic horses were of shorter duration than in healthy ponies.

Four cases of omental herniation in cattle

Four cases in cattle of omental herniation through an acquired omental rent are described. Clinical signs were indistinguishable from other causes of mechanical ileus and exploratory laparotomy was necessary to establish a diagnosis. In all cases a variably sized portion of jejunal loops was obstructed in an omental rent in the deep layer of the greater omentum. In two cases simple reduction was possible, and in one case incision of the hernial ring was necessary before reduction could be performed. Resection was necessary only in a calf, in which the incarceration was complicated by severe abomasal distension and local peritonitis. In all four cases the omental rent was closed by a serosa-serosa suture. Three cases made an uneventful recovery and returned to normal production, but one of these animals died three months postoperatively from an unknown cause. The calf was euthanased two days postoperatively because of persistent ileus.

Adenomyoepitheliomatous lesions of the mammary glands in transgenic mice with targeted PLAG1 overexpression

PLAG1 proto-oncogene overexpression has been causally linked to multiple tumors, highlighting its broad tumorigenic relevance. Here, the oncogenic potential of PLAG1 in mammary gland tumorigenesis was investigated in PLAG1 transgenic mice. To target mammary glands, mice of 2 independent PLAG1 transgenic strains, PTMS1 and PTMS2, in which PLAG1 expression can be modulated by Cre-mediation, were crossed with MMTV-Cre transgenic mice, resulting in P1-MCre and P2-MCre offspring, respectively. Hundred percentage of P1-MCre female mice showed mammary gland hyperplasia, caused by adenomyoepithelial adenosis, at 8 weeks. The tumorigenic process could not be studied further in P1-MCre mice, because concomitant fast-growing salivary gland tumors required euthanasia. Sixteen percentage of P2-MCre females developed mammary gland adenomyoepitheliomas within 30-45 weeks, and none displayed concomitant salivary gland tumors. To further study mammary gland tumorigenesis in PTMS1-derived mice, intercrossing with WAP-Cre transgenic mice, resulting in P1-WAPCre mice, was performed to target PLAG1 expression more specifically to mammary glands. Eighty percentage of such mice developed adenomyoepitheliomas within 53-88 weeks. All PLAG1-induced adenomyoepitheliomas revealed expression upregulation of Igf2/H19, Dlk1/Gtl2, Igfbps and Wnt signaling genes (Wnt6, Cyclin D1). Collectively, these results establish the oncogenic potential of PLAG1 in mammary glands of mice and point towards contributing roles of Igf and Wnt signaling.

Upregulation of Igf and Wnt signalling associated genes in pleomorphic adenomas of the salivary glands in PLAG1 transgenic mice

The Pleomorphic adenoma gene 1 (PLAG1) is involved in various human neoplasias, including pleomorphic adenomas of the salivary glands. Moreover, the oncogenic role of PLAG1 was clearly demonstrated in two independent PLAG1 transgenic mouse founders, in which PLAG1 expression could be targeted to different tissues using the Cre/loxP system. MMTV-Cre-mediated targeted overexpression of PLAG1 in the salivary glands of double transgenic offspring mice, referred to as P1-MCre and P2-MCre mice, induced pleomorphic adenomas in this organ. Igf2, a genuine PLAG1 target gene, was highly upregulated in those tumours as well as in human pleomorphic adenomas of the salivary glands. These and previous observations in other PLAG1-induced tumours e.g. breast adenomyoepitheliomas emphasize the importance of Igf upregulation in such tumours. In this study, further evidence for the role of Igf2 in PLAG1-induced tumourigenesis, is reported. Inactivation of Igf2 in P1-MCre mice leads to a significant delay in tumour development. Since tumour development is not fully abrogated by inactivation of Igf2, other signalling pathways are likely to contribute to PLAG1-induced tumourigenesis as well. Further studies revealed that several genes such as H19, Dlk1, Gtl2, Igfbp2, Igfbp3 and genes involved in Wnt signalling, such as Wnt6, Cyclin D1 and beta-catenin are upregulated in P1-MCre mice in which Igf2 is inactivated. In conclusion, we clearly demonstrate upregulation of several genes associated with Igf and Wnt signalling in PLAG1-induced pleomorphic adenomas. Furthermore, inactivation of Igf2 does not affect upregulation of genes associated with Wnt signalling, which might suggest that both signalling pathways are involved.

MMTV-cre-mediated fur inactivation concomitant with PLAG1 proto-oncogene activation delays salivary gland tumorigenesis in mice

Proprotein convertases are serine endoproteases implicated in the proteolytic processing of a large variety of regulatory proteins. An important role of proprotein convertases in tumorigenic processes has been suggested by various studies. In this study, the role of the proprotein convertase furin in PLAG1 proto-oncogene-induced salivary gland tumorigenesis was investigated. PLAG1 overexpression in salivary glands has previously been shown to result in salivary gland tumors in 100% of mice within 5 weeks after birth. MMTV-cre-mediated inactivation of fur without over-expression of PLAG1 caused smaller but histologically normal salivary glands. Moreover, the lymph nodes close to the salivary glands were enlarged, and histology showed that they had activated follicles. When genetic ablation of 1 or 2 alleles of fur and overexpression of the PLAG1 transgene were simultaneously achieved, a significant delay in tumorigenesis was observed. Collectively, these results suggest an important role for furin in PLAG1-induced salivary gland tumorigenesis in mice.