Reduced STMN2 and pathogenic TDP-43, two hallmarks of ALS, synergize to accelerate motor decline in mice.

Pathological TDP-43 loss from the nucleus and cytoplasmic aggregation occurs in almost all cases of ALS and half of frontotemporal dementia patients. Stathmin2 (Stmn2) is a key target of TDP-43 regulation and aberrantly spliced Stmn2 mRNA is found in patients with ALS, frontotemporal dementia, and Alzheimer's Disease. STMN2 participates in the axon injury response and its depletion in vivo partially replicates ALS-like symptoms including progressive motor deficits and distal NMJ denervation. The interaction between STMN2 loss and TDP-43 dysfunction has not been studied in mice because TDP-43 regulates human but not murine Stmn2 splicing. Therefore, we generated trans-heterozygous mice that lack one functional copy of Stmn2 and express one mutant TDP-43Q331K knock-in allele to investigate whether reduced STMN2 function exacerbates TDP-43-dependent pathology. Indeed, we observe synergy between these two alleles, resulting in an early onset, progressive motor deficit. Surprisingly, this behavioral defect is not accompanied by detectable neuropathology in the brain, spinal cord, peripheral nerves or at neuromuscular junctions (NMJs). However, the trans-heterozygous mice exhibit abnormal mitochondrial morphology in their distal axons and NMJs. As both STMN2 and TDP-43 affect mitochondrial dynamics, and neuronal mitochondrial dysfunction is a cardinal feature of many neurodegenerative diseases, this abnormality likely contributes to the observed motor deficit. These findings demonstrate that partial loss of STMN2 significantly exacerbates TDP-43-associated phenotypes, suggesting that STMN2 restoration could ameliorate TDP-43 related disease before the onset of degeneration.

Cytoskeleton remodeling induced by SMYD2 methyltransferase drives breast cancer metastasis.

Malignant forms of breast cancer refractory to existing therapies remain a major unmet health issue, primarily due to metastatic spread. A better understanding of the mechanisms at play will provide better insights for alternative treatments to prevent breast cancer cell dispersion. Here, we identify the lysine methyltransferase SMYD2 as a clinically actionable master regulator of breast cancer metastasis. While SMYD2 is overexpressed in aggressive breast cancers, we notice that it is not required for primary tumor growth. However, mammary-epithelium specific SMYD2 ablation increases mouse overall survival by blocking the primary tumor cell ability to metastasize. Mechanistically, we identify BCAR3 as a genuine physiological substrate of SMYD2 in breast cancer cells. BCAR3 monomethylated at lysine K334 (K334me1) is recognized by a novel methyl-binding domain present in FMNLs proteins. These actin cytoskeleton regulators are recruited at the cell edges by the SMYD2 methylation signaling and modulate lamellipodia properties. Breast cancer cells with impaired BCAR3 methylation lose migration and invasiveness capacity in vitro and are ineffective in promoting metastases in vivo. Remarkably, SMYD2 pharmacologic inhibition efficiently impairs the metastatic spread of breast cancer cells, PDX and aggressive mammary tumors from genetically engineered mice. This study provides a rationale for innovative therapeutic prevention of malignant breast cancer metastatic progression by targeting the SMYD2-BCAR3-FMNL axis.

Cytoskeleton remodeling induced by SMYD2 methyltransferase drives breast cancer metastasis.

Malignant forms of breast cancer refractory to existing therapies remain a major unmet health issue, primarily due to metastatic spread. A better understanding of the mechanisms at play will provide better insights for alternative treatments to prevent breast cancer cells dispersion. Here, we identify the lysine methyltransferase SMYD2 as a clinically actionable master regulator of breast cancer metastasis. While SMYD2 is overexpressed in aggressive breast cancers, we notice that it is not required for primary tumor growth. However, mammary-epithelium specific SMYD2 ablation increases mouse overall survival by blocking the primary tumor cells ability to metastasize. Mechanistically, we identify BCAR3 as a genuine physiological substrate of SMYD2 in breast cancer cells. BCAR3 monomethylated at lysine K334 (K334me1) is recognized by a novel methyl-binding domain present in FMNLs proteins. These actin cytoskeleton regulators are recruited at the cell edges by the SMYD2 methylation signaling and modulates lamellipodia properties. Breast cancer cells with impaired BCAR3 methylation loose migration and invasiveness capacity in vitro and are ineffective in promoting metastases in vivo . Remarkably, SMYD2 pharmacologic inhibition efficiently impairs the metastatic spread of breast cancer cells, PDX and aggressive mammary tumors from genetically engineered mice. This study provides a rationale for innovative therapeutic prevention of malignant breast cancer metastatic progression by targeting the SMYD2-BCAR3-FMNL axis.

Axillary lymph node dissection versus radiotherapy in breast cancer with positive sentinel nodes after neoadjuvant therapy (ADARNAT trial).

Introduction: Breast cancer surgery currently focuses on de-escalating treatment without compromising patient survival. Axillary radiotherapy (ART) now replaces axillary lymph node dissection (ALND) in patients with limited sentinel lymph node (SLN) involvement during the primary surgery, and this has significantly reduced the incidence of lymphedema without worsening the prognosis. However, patients treated with neoadjuvant systemic treatment (NST) cannot benefit from this option despite the low incidence of residual disease in the armpit in most cases. Data regarding the use of radiotherapy instead of ALND in this population are lacking. This study will assess whether ART is non-inferior to ALND in terms of recurrence and overall survival in patients with positive SLN after NST, including whether it reduces surgery-related adverse effects. Methods and analyses: This multicenter, randomized, open-label, phase 3 trial will enroll 1660 patients with breast cancer and positive SLNs following NST in approximately 50 Spanish centers over 3 years. Patients will be stratified by NST regimen and nodal involvement (isolated tumoral cells or micrometastasis versus macrometastasis) and randomly assigned 1:1 to ART without ALND (study arm) or ALND alone (control arm). Level 3 and supraclavicular radiotherapy will be added in both arms. The primary outcome is the 5-year axillary recurrence determined by clinical and radiological examination. The secondary outcomes include lymphedema or arm dysfunction, quality of life based (EORTC QLQ-C30 and QLQ-BR23 questionnaires), disease-free survival, and overall survival. Discussion: This study aims to provide data to confirm the efficacy and safety of ART over ALND in patients with a positive SLN after NST, together with the impact on morbidity. Ethics and dissemination: The Research Ethics Committee of Bellvitge University Hospital approved this trial (Protocol Record PR148/21, version 3, 1/2/2022) and all patients must provide written informed consent. The involvement of around 50 centers across Spain will facilitate the dissemination of our results. Trial registration: ClinicalTrials.gov, identifier number NCT04889924.

Quiste odontogénico ortoqueratinizado. A propósito de un caso

El quiste odontogénico ortoqueratinizado es un quiste odontogénico de desarrollo poco común. Los maxilares son el sitio más común de afectación. Los quistes mandibulares con queratinización, el queratoquiste odontogénico (OKC) y el quiste odontogénico ortoqueratinizado (OOC) son los que han atraído una mayor atención. Se presenta el caso de una paciente de sexo femenino de 34 años de edad, con historia de 2 meses de evolución de tumefacción de crecimiento progresivo en región de seno maxilar izquierdo acompañado de rinorrea mucopurulenta y salida se secreción purulenta por fístula oroantral. Se realiza cirugía bajo anestesia general, se constata una lesión quística de contenido queratínico en seno maxilar cuya histopatología retorna compatible con Quiste odontogénico ortoqueratinizado.

The orthokeratinized odontogenic cyst is an odontogenic cyst of uncommon development. The jaws are the most common site of involvement. Cysts of the jaw with keratinization, the odontogenic keratocyst (OKC), and the orthokeratinized odontogenic cyst (OOC) have attracted the most attention. The case of a 34-year-old female patient is presented, with a 2-month history of progressively growing swelling in the region of the left maxillary sinus accompanied by mucopurulent rhinorrhea and purulent discharge from an oroantral fistula. Surgery is performed under general anesthesia, a cystic lesion with keratin content is verified in the maxillary sinus whose histopathology returns compatible with orthokeratinized odontogenic cyst.

Quiste odontogénico ortoqueratinizado. A propósito de un caso / Orthokeratinized odontogenic cyst. A case report

El quiste odontogénico ortoqueratinizado es un quiste odontogénico de desarrollo poco común. Los maxilares son el sitio más común de afectación. Los quistes mandibulares con queratinización, el queratoquiste odontogénico (OKC) y el quiste odontogénico ortoqueratinizado (OOC) son los que han atraído una mayor atención. Se presenta el caso de una paciente de sexo femenino de 34 años de edad, con historia de 2 meses de evolución de tumefacción de crecimiento progresivo en región de seno maxilar izquierdo acompañado de rinorrea mucopurulenta y salida se secreción purulenta por fístula oroantral. Se realiza cirugía bajo anestesia general, se constata una lesión quística de contenido queratínico en seno maxilar cuya histopatología retorna compatible con Quiste odontogénico ortoqueratinizado.

The orthokeratinized odontogenic cyst is an odontogenic cyst of uncommon development. The jaws are the most common site of involvement. Cysts of the jaw with keratinization, the odontogenic keratocyst (OKC), and the orthokeratinized odontogenic cyst (OOC) have attracted the most attention. The case of a 34-year-old female patient is presented, with a 2-month history of progressively growing swelling in the region of the left maxillary sinus accompanied by mucopurulent rhinorrhea and purulent discharge from an oroantral fistula. Surgery is performed under general anesthesia, a cystic lesion with keratin content is verified in the maxillary sinus whose histopathology returns compatible with orthokeratinized odontogenic cyst.

Management of the axilla in postmenopausal patients with cN0 hormone receptor-positive/HER2-negative breast cancer treated with neoadjuvant endocrine therapy and its prognostic impact.

PURPOSE: To evaluate the differences in nodal positivity if the sentinel lymph node biopsy (SLNB) is performed before or after neoadjuvant endocrine therapy (NET) in breast cancer patients, and its impact on prognosis. METHODS: A retrospective cohort study was performed in a single center including 91 postmenopausal cases with clinically node-negative and hormone receptor-positive/HER2-negative (HR + /HER2-) breast cancer, treated with NET and SLNB. SLNB was done pre-NET until 2014, and post-NET thereafter. Axillary lymph node dissection (ALND) was indicated only in SLNB macrometastasis, although in selected elderly patients, it was omitted. Kaplan-Meier survival curves were estimated in relation to the status of the axilla, and the differences assessed using the log-rank test. RESULTS: Between December 2006 and March 2022, SLNB was performed pre-NET in 14 cases and post-NET in 77. Both groups were similar in baseline tumor and patient characteristics. SLNB positivity was similar regardless of whether SLNB was performed before (5/14, 35.7%) or after NET (27/77, 37%), with 2/14 SLN macrometastases in the pre-NET cohort and 17/77 in the post-NET cohort. Only three patients (18.7%) with SLN macrometastasis had > 3 positive nodes following ALND. The 5-year overall survival and distant disease-free survival were 92.4% and 94.8%, respectively, with no significant differences according to SLNB status (p 0.5 and 0.8, respectively). CONCLUSION: SLN positivity did not differ according to its timing (before or after NET). Therefore, NET has no effect on lymph node clearance. Furthermore, the prognosis is good regardless of the axillary involvement. Therefore, factors other than axillary involvement may affect the prognosis in these patients.

Comprehensive molecular phenotyping of ARID1A-deficient gastric cancer reveals pervasive epigenomic reprogramming and therapeutic opportunities.

OBJECTIVE: Gastric cancer (GC) is a leading cause of cancer mortality, with ARID1A being the second most frequently mutated driver gene in GC. We sought to decipher ARID1A-specific GC regulatory networks and examine therapeutic vulnerabilities arising from ARID1A loss. DESIGN: Genomic profiling of GC patients including a Singapore cohort (>200 patients) was performed to derive mutational signatures of ARID1A inactivation across molecular subtypes. Single-cell transcriptomic profiles of ARID1A-mutated GCs were analysed to examine tumour microenvironmental changes arising from ARID1A loss. Genome-wide ARID1A binding and chromatin profiles (H3K27ac, H3K4me3, H3K4me1, ATAC-seq) were generated to identify gastric-specific epigenetic landscapes regulated by ARID1A. Distinct cancer hallmarks of ARID1A-mutated GCs were converged at the genomic, single-cell and epigenomic level, and targeted by pharmacological inhibition. RESULTS: We observed prevalent ARID1A inactivation across GC molecular subtypes, with distinct mutational signatures and linked to a NFKB-driven proinflammatory tumour microenvironment. ARID1A-depletion caused loss of H3K27ac activation signals at ARID1A-occupied distal enhancers, but unexpectedly gain of H3K27ac at ARID1A-occupied promoters in genes such as NFKB1 and NFKB2. Promoter activation in ARID1A-mutated GCs was associated with enhanced gene expression, increased BRD4 binding, and reduced HDAC1 and CTCF occupancy. Combined targeting of promoter activation and tumour inflammation via bromodomain and NFKB inhibitors confirmed therapeutic synergy specific to ARID1A-genomic status. CONCLUSION: Our results suggest a therapeutic strategy for ARID1A-mutated GCs targeting both tumour-intrinsic (BRD4-assocatiated promoter activation) and extrinsic (NFKB immunomodulation) cancer phenotypes.

The NFIB/CARM1 partnership is a driver in preclinical models of small cell lung cancer.

The coactivator associated arginine methyltransferase (CARM1) promotes transcription, as its name implies. It does so by modifying histones and chromatin bound proteins. We identified nuclear factor I B (NFIB) as a CARM1 substrate and show that this transcription factor utilizes CARM1 as a coactivator. Biochemical studies reveal that tripartite motif 29 (TRIM29) is an effector molecule for methylated NFIB. Importantly, NFIB harbors both oncogenic and metastatic activities, and is often overexpressed in small cell lung cancer (SCLC). Here, we explore the possibility that CARM1 methylation of NFIB is important for its transforming activity. Using a SCLC mouse model, we show that both CARM1 and the CARM1 methylation site on NFIB are critical for the rapid onset of SCLC. Furthermore, CARM1 and methylated NFIB are responsible for maintaining similar open chromatin states in tumors. Together, these findings suggest that CARM1 might be a therapeutic target for SCLC.

SMYD3 Impedes Small Cell Lung Cancer Sensitivity to Alkylation Damage through RNF113A Methylation-Phosphorylation Cross-talk.

Small cell lung cancer (SCLC) is the most fatal form of lung cancer, with dismal survival, limited therapeutic options, and rapid development of chemoresistance. We identified the lysine methyltransferase SMYD3 as a major regulator of SCLC sensitivity to alkylation-based chemotherapy. RNF113A methylation by SMYD3 impairs its interaction with the phosphatase PP4, controlling its phosphorylation levels. This cross-talk between posttranslational modifications acts as a key switch in promoting and maintaining RNF113A E3 ligase activity, essential for its role in alkylation damage response. In turn, SMYD3 inhibition restores SCLC vulnerability to alkylating chemotherapy. Our study sheds light on a novel role of SMYD3 in cancer, uncovering this enzyme as a mediator of alkylation damage sensitivity and providing a rationale for small-molecule SMYD3 inhibition to improve responses to established chemotherapy. SIGNIFICANCE: SCLC rapidly becomes resistant to conventional chemotherapy, leaving patients with no alternative treatment options. Our data demonstrate that SMYD3 upregulation and RNF113A methylation in SCLC are key mechanisms that control the alkylation damage response. Notably, SMYD3 inhibition sensitizes cells to alkylating agents and promotes sustained SCLC response to chemotherapy. This article is highlighted in the In This Issue feature, p. 2007.

Metanephric adenoma: molecular study and review of the literature.

INTRODUCTION: Metanephric adenoma (MA) is an uncommon benign tumor accounting for 0.2-0.7% of adult renal epithelial neoplasms. The clinical course is often indolent, but diagnosis should not be delayed since clinical symptoms (hematuria, fever, palpable abdominal mass, and flank pain) may be non-specific and overlap with those of a malign renal neoplasm. We report on 4 cases of AM, for which morphological and mutational analysis were performed. MATERIAL AND METHODS: Immunohistochemical staining was performed on sections cut from paraffin blocks to assess expression of WT1, vimentin, racemase, CK7, CD10 and RCC. Testing for the BRAF gene mutation V600 was carried out using real-time PCR (Cobas® 4800). RESULTS: In all four cases, tumors were visible as well-circumscribed, non-encapsulated masses located in the renal cortex and extending towards the medulla. At immunohistochemical examination, tumor cells stained negative for CK7, CD10 and RCC and positive for both WT1 (nuclear, intense) and vimentin (cytoplasmic, intense, and diffuse). Molecular analysis revealed the BRAF gene mutation V600E in three cases and wild-type BRAF in the fourth. CONCLUSIONS: BRAF molecular mutation analysis may aid diagnosis in cases with atypical histological features, especially in small incisional biopsies when reassessment of surgical treatment may be considered.

An Unusual Case of Desmoplastic Melanoma With Monster Cells Imitating an Atypical Fibroxanthoma.

Numerous cells with very large and irregular nuclei ("monster" cells) have not hitherto been reported in desmoplastic melanoma (DM). Their prognostic significance in melanomas is a matter of debate, although some authors have associated them with more aggressive tumor behavior. We report a mixed DM on the scalp of an 88-year-old woman imitating an atypical fibroxanthoma. Tumor cells stained positive for SOX10, S100, and cyclin D1; BRAF mutation status was negative, and fluorescence in situ hybridization analysis showed copy number gains in 11q13 (cyclin D1) and 6p25 (RREB1), and loss in 6q23 (MYB). Cyclin D1 amplification is associated with poor prognosis in melanoma.

A Systematic Review and Meta-Analysis on Possible Role of Vitamin C in Sepsis.

Sepsis is a substantial healthcare burden, and its management continues to be a major challenge. Prior studies demonstrate conflicting evidence regarding the utility of vitamin C in sepsis. This systematic review and meta-analysis aim to collect data among critically ill patients (sepsis/septic shock), comparing the efficacy of parenteral vitamin C with standard care. A literature review was conducted using databases including PubMed, Web of Science, Google Scholar, and the Cochrane Library to identify randomized controlled trials (RCTs) and observational studies comparing intravenous vitamin C alone or in combination with thiamine or glucocorticoids to the standard of care. We identified 11 RCTs and seven retrospective cohort studies. The primary outcome was 28-day mortality. Secondary outcomes included intensive care unit (ICU) length of stay, change in Sequential Organ Failure Assessment (SOFA) score, duration of vasopressor use, and duration of mechanical ventilation. A total of 18 studies with 4078 patients were included in our final analysis. Overall, we found no mortality reduction in patients treated with vitamin C compared to standard of care (odds ratio (OR) 0.92; 95% confidence interval (CI) 0.78 to 1.09; p = 0.34). Studies that reported a change in SOFA scores, ICU length of stay, duration of mechanical ventilation, or duration of vasopressor use did not show any significant difference between groups. Subgroup analysis with RCT versus observational studies and vitamin C dosage regimens did not show any difference. Among patients with sepsis or septic shock, treatment with vitamin C was not associated with a reduction in mortality, ICU length of stay, change in SOFA score, duration of vasopressor use, or duration of mechanical ventilation. Further studies are needed to demonstrate the potential role of vitamin C in the management of sepsis.

Screening for Innovative Sources of Carotenoids and Phenolic Antioxidants among Flowers.

Flowers have been used for centuries in decoration and traditional medicine, and as components of dishes. In this study, carotenoids and phenolics from 125 flowers were determined by liquid chromatography (RRLC and UHPLC). After comparing four different extractants, the carotenoids were extracted with acetone: methanol (2:1), which led to a recovery of 83%. The phenolic compounds were extracted with 0.1% acidified methanol. The petals of the edible flowers Renealmia alpinia and Lantana camara showed the highest values of theoretical vitamin A activity expressed as retinol activity equivalents (RAE), i.e., 19.1 and 4.1 RAE/g fresh weight, respectively. The sample with the highest total phenolic contents was Punica granatum orange (146.7 mg/g dry weight). It was concluded that in most cases, flowers with high carotenoid contents did not contain high phenolic content and vice versa. The results of this study can help to develop innovative concepts and products for the industry.

NSD2 dimethylation at H3K36 promotes lung adenocarcinoma pathogenesis.

The etiological role of NSD2 enzymatic activity in solid tumors is unclear. Here we show that NSD2, via H3K36me2 catalysis, cooperates with oncogenic KRAS signaling to drive lung adenocarcinoma (LUAD) pathogenesis. In vivo expression of NSD2E1099K, a hyperactive variant detected in individuals with LUAD, rapidly accelerates malignant tumor progression while decreasing survival in KRAS-driven LUAD mouse models. Pathologic H3K36me2 generation by NSD2 amplifies transcriptional output of KRAS and several complementary oncogenic gene expression programs. We establish a versatile in vivo CRISPRi-based system to test gene functions in LUAD and find that NSD2 loss strongly attenuates tumor progression. NSD2 knockdown also blocks neoplastic growth of PDXs (patient-dervived xenografts) from primary LUAD. Finally, a treatment regimen combining NSD2 depletion with MEK1/2 inhibition causes nearly complete regression of LUAD tumors. Our work identifies NSD2 as a bona fide LUAD therapeutic target and suggests a pivotal epigenetic role of the NSD2-H3K36me2 axis in sustaining oncogenic signaling.

The effect of omitting axillary dissection and the impact of radiotherapy on patients with breast cancer sentinel node macrometastases: a cohort study following the ACOSOG Z0011 and AMAROS trials.

PURPOSE: To report the outcomes of implementing the ACOSOG Z0011 and AMAROS trials relevant to clinical practice, and to define target groups in whom to avoid or recommend axillary radiotherapy (ART). We also aimed to analyse the reduction in morbidity when axillary lymph node dissection (ALND) was omitted. METHODS: A retrospective cohort study of T1-T2 patients with macrometastases at sentinel lymph node (SLN) who were treated between 2011 and 2020. Breast surgery included either lumpectomy or mastectomy. Patients with ≤ 2 positive SLN were divided into two cohorts by whether they received ART or not. Survival outcomes and morbidity were analysed by Kaplan-Meyer curves and Cox-regression, respectively. RESULTS: 260 pN1a patients were included and ALND was avoided in 167 (64.2%). According the Z0011 results, 72 (43.1%) received no further ART; and based on AMAROS criteria 95 (56.9%) received ART. Median follow-up was 54 months. The 5-year overall survival was 96.8% in the non-RT cohort and 93.4% in the RT cohort (p = 0.19), while the respective 5-year disease-free survivals were 100% and 92.3% (p = 1.06). Lymphedema developed in 3.6% of patients after SLNB versus 43% after ALND (OR 20.25; 95%CI 8.13-50.43). Decreased upper-extremity range of motion appeared in 8.4% of patients after SLNB versus 31.2% after ALND (OR 4.95; 95%CI 2.45-9.98%). CONCLUSIONS: Our study confirms that omitting ALND is safe and has high survival rates in patients with T1-T2 tumours and ≤ 2 positive SLNs. Adding ART could be a treatment option for patients who present other risk factors. Avoiding ALND with or without ART was associated with significantly less arm morbidity.

Mitotic count: A need for standardization / Recuento mitótico: una necesidad de estandarización

PURPOSE: The mitotic count (MC), number of mitosis per unit area, is a very important parameter frequently used for classification and grading of some tumors. Traditionally, the MC has been expressed in terms of number of mitoses per high power field. The size of the field of view can vary greatly among different microscopes. In order to avoid under or overestimation of mitotic count, a conversion needs to be made. METHODS: A simple formula based on a simple rule of three has been devised to standardize the mitotic count to the reference area by multiplying the number of mitotic figures by a correction factor which has been calculated for the most frequently used microscopes and various common tumors. RESULTS AND CONCLUSIONS: We propose this simple method, which involves only a single multiplication, to standardize the mitotic count to the reference area

OBJETIVO: El recuento mitótico o número de mitosis por unidad de área, es un parámetro muy importante utilizado frecuentemente para clasificar y estadificar ciertos tumores. Tradicionalmente se ha expresado el recuento mitótico en términos de número de mitosis por campos de alta frecuencia. El tamaño del campo de visión puede variar ampliamente entre los diferentes microscopios. A fin de evitar la infraestimación o sobreestimación del recuento mitótico, debe realizarse una conversión. MÉTODOS: Por medio de una simple regla de tres, se ha obtenido una fórmula simple para estandarizar el recuento mitótico. Multiplicando el número de mitosis por un factor de corrección, se obtiene el recuento mitótico estandarizado al área de referencia. Se han calculado los factores de corrección para los microscopios más habituales y para los diferentes tumores comunes. RESULTADOS Y CONCLUSIONES: Proponemos este método simple (únicamente uno por multiplicación) para estandarizar el recuento mitótico con respecto al área de referencia

Mitotic count: A need for standardization.

PURPOSE: The mitotic count (MC), number of mitosis per unit area, is a very important parameter frequently used for classification and grading of some tumors. Traditionally, the MC has been expressed in terms of number of mitoses per high power field. The size of the field of view can vary greatly among different microscopes. In order to avoid under or overestimation of mitotic count, a conversion needs to be made. METHODS: A simple formula based on a simple rule of three has been devised to standardize the mitotic count to the reference area by multiplying the number of mitotic figures by a correction factor which has been calculated for the most frequently used microscopes and various common tumors. RESULTS AND CONCLUSIONS: We propose this simple method, which involves only a single multiplication, to standardize the mitotic count to the reference area.

Heat shock protein HSP90 immunoexpression in equine endometrium during oestrus, dioestrus and anoestrus.

Heat shock proteins play a crucial role in cellular development, proliferation, differentiation and apoptosis. Heat shock protein 90 (HSP90) has been localised in the human endometrium, where its immunoexpression changes during the menstrual cycle. Similar studies have not been done for the equid species, so the present study aimed to describe endometrial HSP90 immunoexpression in mare endometrium. Endometrial biopsies were formalin-fixed and paraffin-embedded, and sections were stained with haematoxylin-eosin in preparation for HSP90 immunohistochemistry. Immunostaining and morphometric analyses were performed on the epithelial lining, endometrial glands and connective stroma during oestrus, dioestrus phase and anoestrus period (n = 7 per phase or period). Immunoexpression was localised in the basal region of the epithelial cells lining the lumen. Immunoexpression was greater during oestrus than during either dioestrus or anoestrus. During anoestrus, there was little immunostaining in the endometrium, suggesting that HSP90 is involved in the functional modulation of sex steroid receptors in cyclic mares. Indeed, the function of HSP90 as a chaperone in the folding of proteins, such as steroid receptors, might explain the greater intensity of immunostaining during the oestrus and dioestrus phases, compared the anoestrus period. We conclude that, in the mare, HSP90 plays a role in endometrial function and that further studies are needed to test whether it is important in pathological conditions as endometritis.