7T Magnetic Resonance Imaging Probabilistic Tractography-Based Evidence of Decussation of the Fibers Between the Lateral Geniculate Nucleus and the Primary Visual Area.

BACKGROUND: Geniculocalcarine fibers are thought to be exclusively ipsilateral. However, recent findings challenged this belief, revealing bilateral recruiting responses in occipitotemporoparietal regions upon unilateral stimulation of the lateral geniculate nucleus (LGN) in humans. This raised the intriguing possibility of bilateral projections to primary visual areas (V1). This study sought to explore the hypothetical decussation of the geniculocalcarine tract. METHODS: 40 healthy individuals' 7T magnetic resonance images from the Human Connectome Project were examined. Employing MRtrix3 software with the constrained spherical deconvolution algorithm, scans were processed. LGN served as the seed region and contralateral regions of interest (splenium of the corpus callosum, posterior commissure, LGN, V1, pulvinar, and superior colliculus) were defined to reconstruct the hypothetical decussated fibers. Tractography included contralateral V1 as the target region in all segmentations, excluding ipsilateral V1 to eliminate fibers leading to or originating from this area. Additionally, a segmentation of the tract originating from LGN and projecting to the ipsilateral V1 was performed. Mean fraction anisotropy and mean diffusivity metrics were extracted from the density maps. RESULTS: Observations revealed a substantial volume of decussated fibers between LGN and contralateral V1 via the splenium of the corpus callosum, albeit much smaller than ipsilateral fibers. The volume of ipsilateral fibers was similar in both sides. Left LGN-originating decussated fibers were more than double those originating from the right LGN. Tract segmentation to other regions of interests yielded no fibers. CONCLUSIONS: This study suggests a partial decussation of the fibers between LGN and V1, likely constituting the geniculocalcarine tract.

The clinical effect of intravenous lipid emulsion on rabbits medicated with diazepam.

Intravenous lipid emulsions (ILE) have been increasingly used to reverse a wide range of lipophilic drug intoxications. However, it is still unknown if these emulsions interfere with other lipophilic drugs routinely used while treating intoxicated patients, such as diazepam, one of the main antiepileptic drugs. Therefore, the objective of the present study was to evaluate whether the administration of a 20% ILE interferes with diazepam's clinical effect. We randomly allocated thirty rabbits to five groups. Three of those groups received diazepam (1.0 mg/kg, IV), one of which did not receive any additional treatment, while the two remaining groups were treated with ILE or lactated ringer solution (1.5 mL/kg followed by 0.25 mL/kg/min for 30 min). The fourth group only received lipid emulsion, and the fifth only lactated ringer. Successive neurological exams at 20 min intervals for a total of 100 min were performed to assess the rabbits' neurological state. We concluded that the ILE did not interfere with diazepam's clinical effect but, although unlikely, the possibility of recurrence of a sedative effect should be considered.

Synovial fluid as an auxiliary diagnostic tool for different stages of canine visceral leishmaniasis / Líquido sinovial como ferramenta diagnóstica auxiliar da leishmaniose visceral canina em diferentes estádios

ABSTRACT: Leishmaniasis represents a complex of chronic diseases with a broad geographic distribution and a high significance in public health worldwide. The varied clinical signs in conjunction with the low sensitivity and specificity of canine visceral leishmaniasis (CVL) detection methods make diagnosis of the disease complex. Among the several available laboratory tests, studies have suggested that the detection of parasites in synovial fluid (SF) is a good auxiliary tool in the diagnosis of CVL. However, no study has evaluated the influence of the clinical stage of CVL in the detection of Leishmania sp. in SF. This study aimed to evaluate the detection of Leishmania sp. amastigotes in the SF of dogs at different stages of the disease. The negative control group (G1) comprised 12 dogs that tested negative for CVL. Thirty-six other dogs, tested serologically positive for CVL, were divided into two groups: Group 2 (G2), which included animals at stage II of the disease (moderate; n=18), and Group 3 (G3) included animals at stage III of the disease (severe; n=18). The analysis of SF revealed the presence of parasites in six (33.3%) dogs from G2 and in 16 (88.9%) dogs from G3 (p=0.0437). The present research suggested that SF analysis is of high value as a supplementary tool in the diagnosis of CVL. As a new finding, the present study also indicated that this test has a higher sensitivity in animals presenting with more severe stage of the disease.

RESUMO: As leishmanioses representam um complexo de doenças de caráter crônico de alta importância na saúde pública mundial e com distribuição geográfica ampla. A apresentação clínica variada e a baixa sensibilidade e especificidade de alguns métodos para a detecção da doença tornam complexo o diagnóstico da leishmainiose visceral canina (LVC). Entre os diversos testes laboratóriais disponíveis, estudos tem sugerido que a pesquisa de parasitos no líquido sinovial (LS) pode ser uma ferramenta auxiliar no diagnóstico da LVC. Apesar disso, inexistem estudos avaliando a relação entre o estágio clínico da doença e a detecção de Leishmania sp. no LS. Dessa forma, o presente trabalho teve como objetivo avaliar a detecção de amastigotas de Leishmania sp. no LS de cães acometidos por diferentes estádios da doença. Foram avaliados 48 cães, sendo 12 negativos para LVC (grupo controle negativo, G1) e 36 soropositivos. O grupo 2 (doença moderada, G2) incluiu animais classificados no estádio II da doença, enquanto o grupo 3 (doença grave, G3) abrangeu animais classificados em estádio III. Na análise do líquido sinovial dos cães, o parasito foi visualizado em seis (33,3%) cães do G2 e 16 (88,9)% dos cães de G3 (p=0.0437). O presente trabalho sugere que a análise do LS apresenta alto valor como ferramenta suplementar no diagnóstico da LVC. Em adição, o presente estudo indica, pela primeira vez, que o teste apresenta uma sensibilidade maior em animais que apresentam a forma grave da doença.

Immunodiagnosis of canine visceral leishmaniasis using mimotope peptides selected from phage displayed combinatorial libraries.

ELISA and RIFI are currently used for serodiagnosis of canine visceral leishmaniasis (CVL). The accuracy of these tests is controversial in endemic areas where canine infections by Trypanosoma cruzi may occur. We evaluated the usefulness of synthetic peptides that were selected through phage display technique in the serodiagnosis of CVL. Peptides were chosen based on their ability to bind to IgGs purified from infected dogs pooled sera. We selected three phage clones that reacted only with those IgGs. Peptides were synthesized, polymerized with glutaraldehyde, and used as antigens in ELISA assays. Each individual peptide or a mix of them was reactive with infected dogs serum. The assay was highly sensitive and specific when compared to soluble Leishmania antigen that showed cross-reactivity with anti-T. cruzi IgGs. Our results demonstrate that phage display technique is useful for selection of peptides that may represent valuable synthetic antigens for an improved serodiagnosis of CVL.

Evaluation of adverse effects in tamoxifen exposed healthy female dogs.

BACKGROUND: Mammary tumors are among the most frequent neoplasms in female dogs, but the strategies employed in animal treatment are limited. In human medicine, hormone manipulation is used in cancer therapy. Tamoxifen citrate is a selective inhibitor of oestrogen receptors and exerts a potent anti-oestrogen effect on the mammary gland. The aim of this study was to evaluate the adverse effects when exposing healthy female dogs to tamoxifen. METHODS: Tamoxifen was administered for 120 days at a dose of 0.5 or 0.8 mg/kg/day to either intact or spayed female dogs. The effects were assessed through clinical examination, haematology, serum biochemistry, ophthalmology and bone marrow aspirate examination. Ovariohysterectomy was performed and the uterus examined by histopathology. RESULTS: Vulva oedema and purulent vaginal discharge developed with 10 days of tamoxifen exposure in all groups. Pyometra was diagnosed after around 90 days of exposure in intact females with frequencies increasing during the following 30 days of exposure. Up to 50% of dogs within the groups developed retinitis but none of the dogs had signs of reduced visual acuity. The prevalence of retinitis in each group was similar after 120 days of exposure. Haematological, biochemical and bone marrow changes were not observed. Due to the high risk of developing pyometra after prolonged exposure to tamoxifen, only spayed animals should be given this medication. CONCLUSIONS: A dose of 0.8 mg tamoxifen/kg body weight/day is recommended when treating tamoxifen-responsive canine mammary tumors. Due to the high risk of developing pyometra, ovariohysterectomy is recommended.

relato de caso

A hepatite infecciosa canina é uma enfermidade que provoca lesões nas células endoteliais de diversos tecidos e hepáticas,culminando com sinais clínicos como hemorragias e icterícia, além de alterações das funções renal, hepática egastrintestinais. É de ocorrência rara, mesmo naqueles animais não vacinados ou jovens e, por isso, não é comum o clínicomédico-veterinário suspeitar deste diagnóstico, não solicitando exames laboratoriais confirmatórios. O presente trabalhodescreve a manifestação clínica e o tratamento aplicado a um animal portador de hepatite infecciosa canina.

Perfil hematológico de ratas adultas hipotireóideas castradas e não castradas / Blood profile of hypothyroid castrated or intact adult female rats

A relação tireóide-gônadas sobre o perfil hematológico foi investigada em ratas Wistar adultas castradas e não castradas mantidas em hipotireoidismo induzido pela administração diária de propiltiouracil por 120 dias. Dois grupos eutireóideos não castrado e castrado foram mantidos nas mesmas condições e serviram como controle. Foram colhidos o plasma para dosagem de T4 livre e o sangue para análise hematológica. Os valores de T4 livre significativamente menores nas ratas tratadas confirmaram seu estado hipotireóideo. O hipotireoidismo causou anemia apenas em ratas com gônadas funcionais, já que a castração reverteu os efeitos do déficit de tiroxina sobre o eritrograma. Tanto o hipotireoidismo quanto o hipogonadismo apresentaram pouco significado sobre o leucograma.

[Blood profile of hypothyroid castrated or intact adult female rats]. / Perfil hematológico de ratas adultas hipotireóideas castradas e não castradas.

The relationship between thyroid-gonads on the blood profile was investigated in adult Wistar female rats. These animals were either castrated or intact and were kept under hypothyroidism, induced by daily administration of propylthiouracil (PTU) during 120 days. Two groups (castrated and intact) were kept in an euthyroid condition and used as controls. It was collected plasma for free T4 dosage and blood for hematological analysis. The significant low values of free T4 in the treated rats confirmed their hypothyroid state. The hypothyroidism caused anemia in the rats with functional gonads. The castration reverted the effects of thyroxine deficit in the erythrogram. Both the hypothyroidism and the hypogonadism showed just a discret effect on the leucogram.