Mammalian and reptilian vascular tissues present basal release of 6-nitrodopamine, which is reduced when the tissues are pre-incubated with the NO synthase inhibitor L-NG-Nitro arginine methyl ester (L-NAME), or when the endothelium is mechanically removed. 6-Nitrodopamine induces vasorelaxation in pre-contracted vascular rings by antagonizing the D2-like dopaminergic receptor. Here it was investigated whether male swine vessels (including carotid, left descendent coronary, renal, and femoral arteries) release 6-nitrodopamine, dopamine, noradrenaline, and adrenaline, as measured by liquid chromatography coupled to tandem mass spectrometry. The in vitro vasorelaxant action of 6-nitrodopamine was evaluated in carotid, coronary, renal, and femoral arteries precontracted by U-46619 (3 nM), and compared to that induced by the dopamine D2-receptor antagonist L-741,626. Expression of tyrosine hydroxylase and the neuromaker calretinin was investigated by immunohistochemistry. All vascular tissues presented basal release of endothelium-derived catecholamines. The relaxation induced by 6-nitrodopamine was not affected by preincubation of the tissues with either L-NAME (100 μM, 30-min preincubation) or the heme-site inhibitor of soluble guanylyl cyclase ODQ (100 μM, 30-min preincubation). Electrical field stimulation (EFS)-induced contractions were significantly potentiated by previous incubation with L-NAME, but unaffected by ODQ preincubation. The contractions induced by EFS were reduced by preincubation with either 6-nitrodopamine or L-741,626. Immunohistochemistry in all arteries revealed the presence of tyrosine hydroxylase in the endothelium, whereas immunoreactivity for calretinin was negative. Swine vessels present basal release of endothelium-derived catecholamines and expression of tyrosine hydroxylase in the endothelium. The vasodilation induced by 6-nitrodopamine is due to blockade of dopaminergic D2-like receptors.

BACKGROUND: Histological techniques are essential for the microscopic study and investigation of the human dental pulp. The aim of this study was to evaluate the impact of decalcification-free technique by examining dental pulp morphology by histological staining with haematoxylin and eosin and immunohistochemistry.
METHODS: The sample consisted of 30 healthy third molars extracted for orthodontic indication, the pulp tissue was obtained by removing the mineralized tissues, separating the enamel and dentine and by marking with a flexible diamond disc on the coronal surface and longitudinal axis of the root. These guides made it possible to separate the fragments and obtain the pulp tissue for fixation and staining with H&E and subsequent immunohistochemistry with CD34 and S-100 antibodies.
RESULTS: The technique showed preservation of pulp morphology with adequate preservation of microscopic structures. No alterations in tissue viability were observed. The staining allowed an accurate assessment of vascular and nervous components by means of CD34 and S-100 markers, respectively.
CONCLUSIONS: This technique allows preservation of pulp tissue, maintaining viable tissue for histological analysis and immunohistochemistry tests, as well as reducing sample processing time.

The uncommon, benign dysembryoplastic neuroepithelial tumor (DNET, WHO grade 1) is frequently linked to epilepsy. It is a glioneuronal neoplasm in the cerebral cortex of children or young adults defined by the presence of a pathognomonic glioneuronal element that may be linked to glial nodules and activating mutations of fibroblast growth factor receptor 1 (FGFR1) (CNS WHO grade 1 according to WHO classification of CNS and pituitary tumors, 2021 ). The cerebral cortex is primarily affected. The most frequent areas are the temporal lobe, particularly the medial lobe, frontal lobe, and other cortex. This study reports the instance of a 31-year-old male who had a history of seizures for the past 20 years and complained of a sudden headache and vomiting at the hospital. MRI revealed a cortical-based lesion in the left posterior temporo-occipital region. A biopsy sample was sent for histopathological examination. DNETs are usually benign, non-recurring lesions and rarely can be a malignant transformation. Although they are frequently stable tumors, surgical excision seldom results in recurrence.

Cutaneous granular cell tumors (GCTs) are rare tumors that typically exhibit benign clinical behavior and are likely of Schwann cell origin. Some histologic and immunohistochemical variants of GCTs may present challenges due to infiltrative growth patterns, perineural invasion, and expression of Melan-A. In this case report, we present a 27-year-old male who had previously been diagnosed with a typical GCT on the back a few years ago. The current biopsy from the proximal palm demonstrated a cytologically similar tumor with extensive perineural spread and notable positivity for Melan-A. Although uncommon, these features are consistent with the histological appearances of GCTs. The current views on the histogenesis of GCTs, clinical associations, differential diagnosis with melanoma, and histological criteria for malignant GCTs are discussed. A panel of immunohistochemical stains, including Inhibin-α and preferentially expressed antigen in melanoma (PRAME), is proposed for use in rare instances of Melan-A-positive GCTs.

Granular cell tumor (GCT) is an uncommon neoplasm arising from perineural Schwann cells that can arise anywhere in the body and is particularly rare in the breast. Imaging typically shows an irregular, noncalcified mass with high density on mammography and intense posterior shadowing on US that mimics malignancy. Benign GCTs can be locally aggressive and invade the skin or chest wall. Core biopsy is necessary for diagnosis. Polygonal- to spindle-shaped cells with prominent cytoplasmic eosinophilic granules show S-100 and CD68 staining on immunohistochemistry and lack cytokeratin, estrogen, or progesterone expression. The vast majority of GCTs are benign, albeit locally infiltrative, tumors cured by wide local excision.

UNASSIGNED: Congenital orofacial swellings in neonates are mainly limited to vascular malformations and neuroectodermal benign tumours. Congenital granular cell tumour (CGCT) is a rare condition affecting neonates with a prevalence rate of 6 in 1 million. Our report provides a brief review of diagnosis and management.
UNASSIGNED: A 4-day-old female neonate was brought in with the chief complaint of a single, lobulated mass protruding from the right side of the oral cavity. The inability to achieve lip seal and suckling resulting in feeding problems was the primary concern.
UNASSIGNED: Surgical excision of the lesion was carried out under general anaesthesia. Resected mass was confirmed to be a CGCT upon histopathological evaluation.
UNASSIGNED: One-year follow-up showed satisfactory healing with no evidence of recurrence.
UNASSIGNED: Ultrasonography and other imaging modalities help in differentiating it from vascular malformations. Simple surgical excision suffices to treat the condition.

OBJECTIVE: The existing prediction models for metastasis in pheochromocytomas/paragangliomas (PPGLs) showed high heterogeneity in different centers. Therefore, this study aimed to establish new prediction models integrating multiple variables based on different algorithms.
METHODS: Data of patients with PPGLs undergoing surgical resection at the Peking Union Medical College Hospital from 2007 to 2022 were collected retrospectively. Patients were randomly divided into the training and testing sets in a ratio of 7:3. Subsequently, decision trees, random forest, and logistic models were constructed for metastasis prediction with the training set and Cox models for metastasis-free survival (MFS) prediction with the total population. Additionally, Ki-67 index and tumor size were transformed into categorical variables for adjusting models. The testing set was used to assess the discrimination and calibration of models and the optimal models were visualized as nomograms. Clinical characteristics and MFS were compared between patients with and without risk factors.
RESULTS: A total of 198 patients with 59 cases of metastasis were included and classified into the training set (n = 138) and testing set (n = 60). Among all models, the logistic regression model showed the best discrimination for metastasis prediction with an AUC of 0.891 (95% CI, 0.793-0.990), integrating SDHB germline mutations [OR: 96.72 (95% CI, 16.61-940.79)], S-100 (-) [OR: 11.22 (95% CI, 3.04-58.51)], ATRX (-) [OR: 8.42 (95% CI, 2.73-29.24)] and Ki-67 ≥ 3% [OR: 7.98 (95% CI, 2.27-32.24)] evaluated through immunohistochemistry (IHC), and tumor size ≥ 5 cm [OR: 4.59 (95% CI, 1.34-19.13)]. The multivariate Cox model including the above risk factors also showed a high C-index of 0.860 (95% CI, 0.810-0.911) in predicting MFS after surgery. Furthermore, patients with the above risk factors showed a significantly poorer MFS (P ≤ 0.001).
CONCLUSIONS: Models established in this study provided alternative and reliable tools for clinicians to predict PPGLs patients\' metastasis and MFS. More importantly, this study revealed for the first time that IHC of ATRX could act as an independent predictor of metastasis in PPGLs.

In recent years, research on fish has seen remarkable advancements, especially in aquaculture, ornamental fish industry, and biomedical studies. Immunohistochemistry has become crucial in fish research, aiding in physiological and pathological investigations. However, the use of antibodies originally developed for mammals has raised concerns about their cross-reactivity and specificity in fish. This study systematically evaluated the reactivity of commonly used antibodies for diagnostic purposes, especially in fish pathology, including pan-cytokeratin, vimentin, S-100, glial fibrillary acidic protein, and desmin in the tissue of Sparus aurata, Dicentrarchus labrax, Oncorhynchus mykiss, and Carassius auratus. Western immunoblotting was employed to assess antibody specificity. The results revealed that the pan-cytokeratin and glial fibrillary acidic protein antibodies cross-react with all tested fish species, while S-100 demonstrated specific staining in sea bream, goldfish, and rainbow trout tissues. Conversely, vimentin and desmin antibodies displayed no reactivity. In conclusion, the anti-cytokeratin clone AE1/AE3 and the polyclonal rabbit anti-glial fibrillary acidic protein antibody, which are extensively used in mammals, were validated for fish immunohistochemical studies. Regrettably, D33 anti-desmin and V9 anti-vimentin clones are unsuitable for immunohistochemistry in the tested fish. These findings underscore the need for species-specific antibodies and proper validation for accurate immunohistochemistry analyses in fish research.

The fish epidermis (EP) contains several cell types, and it has several functional roles, though the secretory role prevails. The alarm or epidermal club cells (ECCs) represent a voluminous immune cell secreting an alarm substance. Our work targeted the histochemical and immunologic attributes of the ECCs in catfish. Matrix metalloproteinase (MMP-9) immunostaining revealed strong immunoreactive signals in the cytoplasm of all ECCs, while S-100 protein immunoreactivity selectively marked the ECCs. Individual ECCs exhibit intense S-100 immunoreactivity compared to neighboring ECCs. The difference in the intensity of the S-100 immunostaining was associated with the difference in the ECC size. This was confirmed by the semithin results where several developmental stages of ECCs could be distinguished. Some eosinophilic granular cells with their characteristic metachromatic granules were recorded juxtaposing the ECCs. Moreover, some free electron-dense granules could be demonstrated in the intercellular spaces surrounding the ECCs. Collectively, these findings suggest several functional profiles for the catfish ECCs depending on their developmental stage. Most importantly, S-100 immunoreactivity in the ECCs suggests its neuroendocrine function. Moreover, the difference in the intensity and polar distribution of S-100 staining is a sign of its role in the differentiation of the ECCs.

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