Antifouling Activity of Synthetic Alkylpyridinium Polymers Using the Barnacle Model

Polymeric alkylpyridinium salts (poly-APS) isolated from the Mediterranean marine sponge, Haliclona (Rhizoniera) sarai, effectively inhibit barnacle larva settlement and natural marine biofilm formation through a non-toxic and reversible mechanism. Potential use of poly-APS-like compounds as antifouling agents led to the chemical synthesis of monomeric and oligomeric 3-alkylpyridinium analogues. However, these are less efficient in settlement assays and have greater toxicity than the natural polymers. Recently, a new chemical synthesis method enabled the production of poly-APS analogues with antibacterial, antifungal and anti-acetylcholinesterase activities. The present study examines the antifouling properties and toxicity of six of these synthetic poly-APS using the barnacle (Amphibalanus amphitrite) as a model (cyprids and II stage nauplii larvae) in settlement, acute and sub-acute toxicity assays. Two compounds, APS8 and APS12-3, show antifouling effects very similar to natural poly-APS, with an anti-settlement effective concentration that inhibits 50% of the cyprid population settlement (EC₅₀) after 24 h of 0.32 mg/L and 0.89 mg/L, respectively. The toxicity of APS8 is negligible, while APS12-3 is three-fold more toxic (24-h LC₅₀: nauplii, 11.60 mg/L; cyprids, 61.13 mg/L) than natural poly-APS. This toxicity of APS12-3 towards nauplii is, however, 60-fold and 1200-fold lower than that of the common co-biocides, Zn- and Cu-pyrithione, respectively. Additionally, exposure to APS12-3 for 24 and 48 h inhibits the naupliar swimming ability with respective IC₅₀ of 4.83 and 1.86 mg/L.     

Hepatozoonosis in a dog with skeletal involvement and meningoencephalomyelitis

Abstract: A 15‐month‐old, female mongrel dog was presented with a 6‐week history of inappetence, weight loss, and tetraparesis. Physical examination revealed weakness, poor body condition, mild fever, pale mucous membranes, and diffuse muscle atrophy. The right hind limb was painful and edematous, with large ecchymoses. The femur was irregular on palpation and moderate popliteal lymphadenopathy was evident. Results of a CBC showed severe anemia with mild regeneration, an inflammatory leukogram with 90% of neutrophils parasitized by Hepatozoon sp. gamonts, and moderate thrombocytopenia. A bone marrow aspirate had myeloid hyperplasia and contained a few extracellular Hepatozoon meronts and a few intracellular gamonts within neutrophils. Serum chemistry abnormalities included hypoalbuminemia, hyperglobulinemia, hypoglycemia, hypercalcemia, hyperphosphatemia, and elevated alkaline phosphatase activity. Radiologic findings of the right femur included periosteal bone proliferation and lesions compatible with osteomyelitis. A fine needle aspirate specimen from the bone lesion had neutrophilic inflammation; 36% of the neutrophils contained Hepatozoon gamonts. Results of cerebrospinal fluid analysis included a protein concentration of 37 mg/dL and marked mononuclear pleocytosis (243 cell/μL) with a predominance of lymphocytes. An ELISA was positive for Hepatozoon canis and PCR results with DNA sequencing confirmed infection with this organism. A diagnosis of hepatozoonosis with skeletal involvement and meningoencephalomyelitis was made. The dog recovered almost completely neurologically and had no gamonts in the blood after 60 days of therapy with imidocarb dipropionate and prednisone. This is an unusual case of canine hepatozoonosis involving neurologic signs and a periosteal reaction more typical of H. americanum infection and rarely reported in dogs infected with H. canis.     

PCR-RFLP molecular confirmation of color dilution alopecia in dogs in Brazil

Color dilution alopecia (CDA) is a dermatopathy observed exclusively in animals having a diluted coat color. In dogs, color dilution occurs as a result of a single-nucleotide variation (SNV) c.-22G > A in the melanophilin gene. We standardized a PCR–restriction-fragment length polymorphism (PCR-RFLP) technique to identify this mutation and determine its frequency in dogs in Brazil. The standardized PCR-RFLP technique could efficiently identify the SNV c.-22G > A in the melanophilin gene, with mutated allele frequencies of 0.1, 0.1, and 0.0875 in Dachshund, Miniature Pinscher, and Yorkshire Terrier breeds, respectively, with no statistical difference among the breeds (p = 0.252). The mutation was identified in 2 homozygous Dachshund dogs with alopecia, confirming the clinical characteristic of CDA. The standardization of a simpler and more accessible molecular technique for recognition of the SNV c.-22G > A in the melanophilin gene allows identification of heterozygous (phenotypically normal) dogs that can be excluded from reproduction, to avoid the birth of dogs with diluted coat color and consequently CDA.