Tratamiento quirúrgico del carcinoma de Merkel facial avanzado. Presentación de un caso / Surgical treatment of advanced facial Merkel cell carcinoma. A case report

Introducción. El carcinoma de Merkel es un tumor maligno poco frecuente, que afecta principalmente a la población caucásica y cuya etiología guarda relación con el poliomavirus de las células de Merkel. Conlleva mal pronóstico, especialmente en estadios finales. Caso clínico. Se expone el caso de una paciente que presentaba un tumor primario facial de grandes dimensiones, con avanzado grado de extensión, afectación linfática cervical y metástasis parotídea derecha. Fue tratada mediante exéresis de la lesión primaria y cobertura con injerto de piel parcial, linfadenectomía cervical y parotidectomía ipsilateral. Resultados. Se logró mejoría importante en la calidad de vida de la paciente y sobrevida de al menos seis meses. Conclusión. Aunque no está claro el manejo óptimo del carcinoma de Merkel avanzado debido a su mal pronóstico, la cirugía favorece una mejoría en la calidad de vida del paciente y puede tener un papel clave en el manejo del carcinoma de Merkel en los estadios avanzados.

Introduction. Merkel carcinoma is a rare malignant tumor that mainly affects the Caucasian population and whose etiology is related to the Merkel cell polyomavirus. It has a poor prognosis, especially in the final stages. Clinical case. The case of a patient who presented a large primary facial tumor, with an advanced degree of extension, cervical lymphatic involvement and right parotid metastasis is described. She was treated surgically by excision of the primary lesion and coverage with partial skin graft, cervical lymphadenectomy, and ipsilateral parotidectomy. Results. A significant improvement was achieved in the patient's quality of life and survival of at least six months.Conclusion. Although the optimal management of advanced Merkel carcinoma is unclear due to its poor prognosis, surgery improves the patient's quality of life and it can play a key role in the management of Merkel carcinoma in advanced stages.

Lung Transplantation for Multiple Giant Hamartomas: First Case Report and Review of the Literature.

BACKGROUND: To assess lung transplant as a solution for a rare complication of giant lung hamartoma, in which surgical resection was discouraged because of severe underlying chronic lung disease. METHODS: A 54-year-old woman had an episode of severe acute hemoptysis. Imaging techniques showed 2 masses in the right lung as hamartomas and severe pulmonary emphysema. After resolution of the acute episode of hemoptysis, the case could have been solved with a right pneumonectomy; however, a single-lung transplant was performed because of the underlying chronic obstructive pulmonary disease. RESULTS: The outcome of the surgery was satisfactory, although a second operation was required because of bleeding. The patient was discharged and currently has a good quality of life, with no recurrence of the disease. The pathologic anatomy of the surgical specimen confirmed the diagnosis of multiple giant hamartomas. CONCLUSIONS: Lung transplant could be a feasible procedure to treat life-threatening complications of benign tumors in selected patients with pulmonary end-stage disease.

Pathogenic mechanisms involving the interplay between adipose tissue and auto-antibodies in rheumatoid arthritis.

We aimed to evaluate the association between adipose tissue (AT) dysfunction, autoimmunity, and disease activity in rheumatoid arthritis (RA). A cross-sectional study including 150 RA patients and 50 healthy donors and longitudinal study with 122 RA patients treated with anti-tumor necrosis factor (TNF)-α, anti-interleukin 6 receptor (IL6R) or anti-CD20 therapies for 6 months were carried out. In vitro experiments with human AT and adipocyte and macrophage cell lines were performed. A collagen-induced arthritis mouse model was developed. The insulin resistance and the altered adipocytokine profile were associated with disease activity, the presence of anti-citrullinated proteins anti-bodies (ACPAs), and worse response to therapy in RA. AT in the context of arthritis is characterized by an inflammatory state alongside the infiltration of macrophages and B/plasmatic cells, where ACPAs can have a direct impact, inducing inflammation and insulin resistance in macrophages and promoting a defective adipocyte differentiation, partially restored by biologicals.

The ultrastructure of muscle fibers and satellite cells in experimental autoimmune encephalomyelitis after treatment with transcranial magnetic stimulation.

In this study, we investigated the effect of transcranial magnetic stimulation (TMS) on the ultrastructure of muscle fibers and satellite cells in rats with experimental autoimmune encephalomyelitis (EAE). EAE-induced animals were treated with TMS (60 Hz at 0.7 mT) for 2 hours in the morning, once a day, 5 days a week, for 3 weeks, starting on day 15 post-immunization. The rats were sacrificed on day 36 post-immunization, and the soleus muscles were evaluated by light microscopy and transmission electron microscopy. Findings were compared with a non-treated EAE group. Electron microscopy analysis showed the presence of degenerated mitochondria, autophagic vacuoles, and altered myofibrils in non-treated EAE group. This correlates with the presence of acid phosphatase activity in muscle fibers and core-targetoid lesions with desmin immunohistochemistry. Most myonuclei in the EAE group showed apoptotic features. In contrast, EAE induced-TMS treated animals had less ultrastructural changes in the mitochondria and the myofibrils, together with less frequent apoptotic nuclear features. Peripheral desmin+ protrusions, as a marker of active satellite cells, were significantly increased in TMS-treated group. This correlates ultrastructurally with the presence of active features in satellite cells in the TMS group. In conclusion, the attenuation of ultrastructural alterations in muscle fibers and activation response of satellite cells caused by EAE indicated that skeletal muscle had a regenerative response to TMS.

[Analysis of the university teaching organization of Pathological Anatomy in Spain]. / Análisis de la organización docente universitaria de la Anatomía Patológica en España.

INTRODUCTION: To describe and analyze the current situation of Pathology teaching and its characteristics in the degree of Medicine in public medical schools in Spain. METHODS: Descriptive analysis of the teaching guides of the undergraduate studies of 32 Spanish public medical schools, identifying the number of credits, hours of theoretical practical teaching, teaching elements, rotation through hospital services and teachers in the subject of Pathology. RESULTS: In the 32 medical schools analyzed, 31 (96.7%) present in their study plans at least 1 AP subject. Data could not be obtained from one faculty. 67% of the subjects offered imply rotation by AP services. The most frequent year for AP teaching is the third one, and the median number of ECTS credits is 6. 49.5% of the subjects involve contents related to the clinical autopsy. 12.5% of the subjects have either theoretical or practical content on digital Pathology or telepathology. Regarding the teaching staff, 112 people are civil servants (University Professor or Professor, of which 91 are linked -92,9%), 244 people are non-civil servants, where 76.2% have the teaching figure of Associate Professor. CONCLUSIONS: The teaching of Pathology is widely distributed, the rotation of Pathology health services is scarce and the most frequent teaching figure is that of an Associate Professor.

Prognosis and survival of patients diagnosed with well-differentiated and dedifferentiated retroperitoneal liposarcoma.

OBJECTIVES: The main objective is to establish the overall survival and disease-free survival profiles regarding the patients with retroperitoneal liposarcoma, making a comparison based on the well-differentiated and dedifferentiated histological subtypes. The secondary objectives are to descriptively analyze the clinical characteristics of said patients and to identify and analyze other independent variables that might modify these survival profiles significantly. METHODS: An observational and analytical study was performed using a retrospective historical cohort that was followed prospectively. The inclusion criteria consisted of: the procedure of liposarcoma located in the retroperitoneum, the well-differentiated and dedifferentiated histological subtypes, between January of 2002 and May of 2019. As a result, 32 patients took part in this study's sample. Kaplan-Meier estimator was used to summarise the results and log-rank test was used in the comparative analysis. RESULTS: The overall survival at 5 years was around 59%. No differences were found between the patients with a well-differentiated subtype compared to the dedifferentiated ones (p = 0.834). The disease-free survival at 2 years was 59% regarding the well-differentiated and 26% regarding the dedifferentiated, with these differences being statistically significant (p = 0.005). None of the other studied variables modified these survival profiles significantly. CONCLUSIONS: Dedifferentiated retroperitoneal liposarcomas show less disease-free survival than well-differentiated liposarcomas. However, regarding overall survival no differences can be claimed.

Effectiveness of a brief motivational intervention in the management of risky alcohol use in primary care: ALCO-AP20 study protocol.

Background: Motivational interviewing (MI) could be a method for minimizing alcohol-related harm. The study aims to assess the effectiveness of a brief intervention, based on a MI, in patients with risky alcohol use attended in Primary Care (PC). Materials and methods: A cluster-randomized, two-arm parallel, multicenter, open-label, controlled clinical trial. Fifty PC healthcare professionals from the province of Córdoba (Spain) will be randomized to one of the two study groups: (1) Experimental Group (EG): MI-based approach; (2) Control Group (CG): Usual care based on health advice. EG intervention: Professionals will receive a training program focused on MI, consisting of a training workshop and the use of pre- and post-workshop questionnaires to measure knowledge and skills acquired, as well as the degree of empathy, with a videotape of the health professionals with standardized patients, before and after the workshop, and subsequent training feedback. CG intervention: Workshop on the management of risky alcohol use based on health advice; participants will also complete the pre-and post-workshop questionnaires and be videotaped. Study population: Patients ≥ 14 years old with risky alcohol consumption (28 Standard Drink Units-SDU-/week in men and 17 SDU/week in women) or excessive alcohol use (≥ 6 SDU in men or ≥ 4 SDU in women, in less than 2 h). It would be necessary to include 110 subjects/group to find a difference of 20% between the percentage of patients in abstinence between EG (37%) and CG (20%), alpha error of 5%, and statistical power of 80%. Assuming a loss rate of 5% and the cluster design effect, the number of subjects to be recruited is estimated at 197/group. The follow-up period will be 12 months. The primary outcome variables will be the self-reported alcohol use level and the Alcohol Use Disorders Identification Test (AUDIT) questionnaire score. Discussion: The study aims to demonstrate the effectiveness of the motivational approach in the comprehensive treatment of the patient with risky alcohol use, improving the empathy of the healthcare professionals and strengthening the healthcare professional-patient relationship to achieve the behavioral change of the patients with this problem in primary care consultations. Clinical trial registration: ClinicalTrials.gov.

First Report in the Literature of Biopsy-Proven Noncollapsing Focal Segmental Glomerulosclerosis Relapse in a Second Renal Transplant Presenting With Thrombotic Microangiopathy: A Case Report.

Primary focal segmental glomerulosclerosis (FSGS) is a podocytopathy with an irregular response to immunosuppressive therapies. FSGS relapse occurs in 30% to 80% of kidney grafts, and poor survival outcomes include large proteinuria and the nephrotic syndrome's cardinal clinical features. Thrombotic microangiopathy (TMA) is caused by endothelial injury due to complement dysregulation including acute kidney injury, proteinuria, and severe hypertension common renal presentations. Both pathologies have well-described genetic forms, but their relationship remains uncertain. FSGS lesions can be found in kidney biopsy specimens in patients with TMA, and TMA has been reported in patients with collapsing glomerulopathy. However, this combination has not been clearly described in renal transplant recipients. We present the case of a 22-year-old man who received his second kidney allograft and developed an early graft disfunction with nephrotic syndrome and clinical TMA. His background was remarkable for primary, biopsy-confirmed FSGS in childhood, and he started hemodialysis in 2006 and received a living donor kidney graft the same year. He presented with a FSGS relapse with malignant hypertension and seizures in the first posttransplant month and had an irregular response to plasma exchange and rituximab, and dialysis was reinitiated 10 years later. A total of 3 biopsies were performed after his second kidney transplant showing the evolution of a FSGS relapse with histologic and clinical TMA in the absence of identified genetic mutations. Partial responses to treatments with plasma exchange, eculizumab, and rituximab were obtained, but the allograft was lost after 26 months. This case is the first report of concomitant FSGS and TMA in a renal transplant recipient.

Surgical management of Miescher's cheilitis: a case report.

Miescher's cheilitis, also known as cheilitis granulomatosa, is an infrequent disease characterized by chronic recurrent swelling of one lip or both lips. It is considered as one of the three main symptoms of the triad of the Melkersson-Rosenthal syndrome, although in many cases it may develop monosymptomatically. The initial management is based on the administration of corticoids, followed in many cases by the use of other systemic treatments. Nevertheless, because recurrence is quite frequent, surgery remains in many cases as the only definitive treatment. In this report we present the case of a Caucasian woman with Miescher's cheilitis who was successfully surgically managed.

Prognosis and survival of patients diagnosed with well-differentiated and dedifferentiated retroperitoneal liposarcoma. / Pronóstico y supervivencia de pacientes diagnosticados de liposarcoma retroperitoneal bien diferenciado y desdiferenciado.

OBJECTIVES: The main objective is to establish the overall survival and disease-free survival profiles regarding the patients with retroperitoneal liposarcoma, making a comparison based on the well-differentiated and dedifferentiated histological subtypes. The secondary objectives are to descriptively analyze the clinical characteristics of said patients and to identify and analyze other independent variables that might modify these survival profiles significantly. METHODS: An observational and analytical study was performed using a retrospective historical cohort that was followed prospectively. The inclusion criteria consisted of: the procedure of liposarcoma located in the retroperitoneum, the well-differentiated and dedifferentiated histological subtypes, between January 2002 and May 2019. As a result, 32 patients took part in this study's sample. Kaplan-Meier estimator was used to summarize the results and log-rank test was used in the comparative analysis. RESULTS: The overall survival at 5 years was around 59%. No differences were found between the patients with a well-differentiated subtype compared to the dedifferentiated ones (p=0.834). The disease-free survival at 2 years was 59% regarding the well-differentiated and 26% regarding the dedifferentiated, with these differences being statistically significant (p=0.005). None of the other studied variables modified these survival profiles significantly. CONCLUSIONS: Dedifferentiated retroperitoneal liposarcomas show less disease-free survival than well-differentiated liposarcomas. However, regarding overall survival no differences can be claimed.

Ultrasonographic and Histological Correlation after Experimental Reconstruction of a Volumetric Muscle Loss Injury with Adipose Tissue.

Different types of scaffolds are used to reconstruct muscle volume loss injuries. In this experimental study, we correlated ultrasound observations with histological findings in a muscle volume loss injury reconstructed with autologous adipose tissue. The outcome is compared with decellularized and porous matrix implants. Autologous adipose tissue, decellularized matrix, and a porous collagen matrix were implanted in volumetric muscle loss (VML) injuries generated on the anterior tibial muscles of Wistar rats. Sixty days after implantation, ultrasound findings were compared with histological and histomorphometric analysis. The muscles with an autologous adipose tissue implant exhibited an ultrasound pattern that was quite similar to that of the regenerative control muscles. From a histological point of view, the defects had been occupied by newly formed muscle tissue with certain structural abnormalities that would explain the differences between the ultrasound patterns of the normal control muscles and the regenerated ones. While the decellularized muscle matrix implant resulted in fibrosis and an inflammatory response, the porous collagen matrix implant was replaced by regenerative muscle fibers with neurogenic atrophy and fibrosis. In both cases, the ultrasound images reflected echogenic, echotextural, and vascular changes compatible with the histological findings of failed muscle regeneration. The ultrasound analysis confirmed the histological findings observed in the VML injuries reconstructed by autologous adipose tissue implantation. Ultrasound can be a useful tool for evaluating the structure of muscles reconstructed through tissue engineering.

Magnesium supplementation reduces inflammation in rats with induced chronic kidney disease.

BACKGROUND: Inflammation is a common feature in chronic kidney disease (CKD) that appears specifically associated with cardiovascular derangements in CKD patients. Observational studies have revealed a link between low Mg levels and inflammation. In this study, we hypothesize that Mg might have a modulatory effect on the inflammation induced under the uraemic milieu. METHODS: In vivo studies were performed in a 5/6 nephrectomized rat model of CKD. Furthermore, a possible direct effect of Mg was addressed through in vitro studies with vascular smooth muscle cells (VSMCs). RESULTS: Uraemic rats fed a normal (0.1%) Mg diet showed a systemic inflammatory response evidenced by the elevation in plasma of the pro-inflammatory cytokines TNF-α, IL-1ß and IL-6, and GPx activity, a marker of oxidative stress. Importantly, an increased expression of these cytokines in the aortic tissue was also observed. In contrast, a dietary Mg supplementation (0.6%) greatly prevented the oxidative stress and the pro-inflammatory response. In vitro, in VSMCs cultured in a pro-inflammatory high phosphate medium, incubation with Mg 1.6 mM inhibited the increase in the production of ROS, the rise in the expression of TNF-α, IL-1ß, IL-6 and IL-8 and the activation of NF-κB signalling that was observed in cells incubated with a normal (0.8 mM) Mg. CONCLUSION: Mg supplementation reduced inflammation associated with CKD, exerting a direct effect on vascular cells. These findings support a possible beneficial effect of Mg supplementation along the clinical management of CKD patients.

Histology of skeletal muscle reconstructed by means of the implantation of autologous adipose tissue: an experimental study.

The purpose of this study was to determine the histological characteristics of a skeletal muscle reconstructed by means of the implantation of autologous adipose tissue following an experimentally-induced volumetric muscle loss. A cylindrical piece in the belly of the rat anterior tibial muscle was removed. In the hole, inguinal subcutaneous adipose tissue of the same rat was grafted. Animals were sacrificed 7, 14, 21, 28 and 60 days posttransplantation. Histological, histochemical, immunohistochemical and morphometric techniques were used. At all times analyzed, the regenerative muscle fibers formed from the edges of the muscle tissue showed histological, histochemical and immunohistochemical differences in comparison with the control group. These differences are related to delays in the maturation process and are related to problems in reinnervation and disorientation of muscle fibers. The stains for MyoD and desmin showed that some myoblasts and myotubes seem to derive from the transplanted adipose tissue. After 60 days, the transplant area was 20% occupied by fibrosis and by 80% skeletal muscle. However, the neo-muscle was chaotically organized showing muscle fiber disorientation and centronucleated fibers with irregular shape and size. Our results support the hypothesis that, at least from a morphological point of view, autologous adipose tissue transplantation favors reconstruction following a volumetric loss of skeletal muscle by combining the inherent regenerative response of the organ itself and the myogenic differentiation of the stem cells present in the adipose tissue. However, in our study, the formed neo-muscle exhibited histological differences in comparison with the normal skeletal muscle.

Prevalence of hazardous alcohol use among Spanish primary care providers.

BACKGROUND: Alcohol use by health care professionals is one of the potential factors that may affect the prevention of hazardous drinking in Primary Care (PC). The objective of the study was to estimate the prevalence of hazardous alcohol use by PC professionals and assess the existing relationship between socio-demographic and occupational variables of PC professionals and their alcohol use. METHODS: A descriptive, cross-sectional, observational, multicenter study was performed. LOCATION: PC sites of the Spanish National Health Care System (NHS). PARTICIPANTS: Physicians and nurses, who completed an online questionnaire intended to identify the pattern of hazardous alcohol use through the AUDIT-C test. The study population was recruited through random sampling stratified by regions of the PC sites in the NHS. The primary measurements: Frequency of alcohol use, number of drinks containing alcohol on a typical day, frequency of six or more drinks on one occasion. RESULTS: One thousand seven hundred sixty professionals completed the questionnaire. Hazardous alcohol use was detected in 27.80% (95% CI: 25.5-29.7) of PC providers. The prevalence of hazardous alcohol use was higher in males (34.2%) [95% CI: 30.4-37.6] and professionals aged 56 years or over (34.2%) [95% CI: 28.2-40.2]. The multiple logistic regression analysis revealed a higher hazardous use in males (OR = 1.52; 95% CI: 1.22-1.90), PC physicians (OR = 1.42; 95% CI: 1.01-2.02) and professionals with more time worked (OR = 1.03; 95% CI: 1.01-1.05). CONCLUSION: Our study shows the current prevalence of hazardous alcohol use among Spanish PC providers, revealing a higher percentage of hazardous alcohol use in healthcare professionals compared to the Spanish general population. Further interventions are required to increase the awareness of negative consequences derived from alcohol use among PC professionals and its impact on the clinical setting.

Knowledge, attitudes and preventive practices of primary health care professionals towards alcohol use: A national, cross-sectional study.

INTRODUCTION: Primary care (PC) professionals' knowledge about alcohol use has been identified as one of the barriers PC providers face in their clinic. Both PC professionals' level of training and attitude are crucial in the clinical practice regarding alcohol use. OBJECTIVE: To evaluate the knowledge, attitude, and preventive practices of Spanish PC physicians and nurses towards alcohol use. DESIGN: An observational, descriptive, cross-sectional, multi-center study. METHODOLOGY: Location: PC centers of the Spanish National Health System (NHS). Participants: PC physicians and nurses selected randomly from health care centers, and by sending an e-mail to semFYC and SEMERGEN members. Healthcare providers completed an online survey on knowledge, attitude, and follow-up recommendations for reducing alcohol intake. A descriptive, bivariate, and multivariate statistical analysis was conducted (p<0.05). RESULTS: Participants: 1,760 healthcare providers completed the survey (75.6% [95% CI 73.5-77.6] family physicians; 11.4% [95% CI 9.9-12.9] medical residents; and 12.5% [95% CI 10.9-14.1] nurses), with a mean age of 44.7 (SD 11.24, range: 26-64, 95% CI: 47.2-48.2). Knowledge was higher in family physicians (p<0.001), older professionals (Spearman's r = 0.11, p<0.001), and resident trainers (p<0.001). The PC professional most likely to provide advice for reducing alcohol use was: a nurse (p <0.001), female (p = 0.010), between 46 and 55 years old (p <0.001). CONCLUSIONS: PC providers' knowledge and preventive practices regarding alcohol use are scarce, hence specific training strategies to increase their knowledge and improve their attitude and skills with regard to this health problem should be considered a healthcare policy priority.

Denervated muscle extract promotes recovery of muscle atrophy through activation of satellite cells. An experimental study.

PURPOSE: The objective of the present study was to determine whether a denervated muscle extract (DmEx) could stimulate satellite cell response in denervated muscle. METHODS: Wistar rats were divided into 4 groups: normal rats, normal rats treated with DmEx, denervated rats, and denervated rats treated with DmEx. The soleus muscles were examined using immunohistochemical techniques for proliferating cell nuclear antigen, desmin, and myogenic differentiation antigen (MyoD), and electron microscopy was used for analysis of the satellite cells. RESULTS: The results indicate that while denervation causes activation of satellite cells, DmEx also induces myogenic differentiation of cells localized in the interstitial space and the formation of new muscle fibers. Although DmEx had a similar effect in nature on innervated and denervated muscles, this response was of greater magnitude in denervated vs. intact muscles. CONCLUSION: Our study shows that treatment of denervated rats with DmEx potentiates the myogenic response in atrophic denervated muscles.

Histological Changes in Skeletal Muscle During Death by Drowning: An Experimental Study.

A diagnosis of drowning is a challenge in legal medicine as there is generally a lack of pathognomonic findings indicative of drowning. This article investigates whether the skeletal muscle undergoes structural changes during death by drowning. Eighteen Wistar rats were divided into 3 equal groups according to the cause of death: drowning, exsanguination, and cervical dislocation. Immediately after death, samples of the masseter, sternohyoid, diaphragm, anterior tibial, soleus, and extensor digitorum longus muscles were obtained and examined by light and electron microscopy.In the drowning group, all muscles except the masseter displayed scattered evidence of fiber degeneration, and modified Gomori trichrome staining revealed structural changes in the form of abnormal clumps of red material and ragged red fibers. Under the electron microscope, there was myofibrillar disruption and large masses of abnormal mitochondria. In the exsanguination group, modified Gomori trichrome staining disclosed structural changes and mitochondrial abnormalities were apparent under light microscopy; however, there was no evidence of degeneration. No alterations were observed in the cervical dislocation group.As far as we know, this is the first time that these histological findings are described in death by drowning and are consistent with rhabdomyolysis and intense anoxia of skeletal muscle.

Muscular hypertrophy and atrophy in normal rats provoked by the administration of normal and denervated muscle extracts.

This study was conducted to determine the effects of extracts obtained from both normal and denervated muscles on different muscle types. Wistar rats were used and were divided into a control group and four experimental groups. Each experimental group was treated intraperitoneally during 10 consecutive days with a different extract. These extracts were obtained from normal soleus muscle, denervated soleus, normal extensor digitorum longus, and denervated extensor digitorum longus. Following treatment, the soleus and extensor digitorum longus muscles were obtained for study under optic and transmission electron microscope; morphometric parameters and myogenic responses were also analyzed. The results demonstrated that the treatment with normal soleus muscle and denervated soleus muscle extracts provoked hypertrophy and increased myogenic activity. In contrast, treatment with extracts from the normal and denervated EDL had a different effect depending on the muscle analyzed. In the soleus muscle it provoked hypertrophy of type I fibers and increased myogenic activity, while in the extensor digitorum longus atrophy of the type II fibers was observed without changes in myogenic activity. This suggests that the muscular responses of atrophy and hypertrophy may depend on different factors related to the muscle type which could be related to innervation.

Skeletal muscle findings in experimental autoimmune encephalomyelitis.

INTRODUCTION: Skeletal muscle is a target organ in multiple sclerosis, a chronic debilitating disease of the central nervous system caused by demyelination and axonal deterioration. Since the experimental autoimmune encephalomyelitis model reproduces the relapsing-remitting course found in most multiple sclerosis patients, this model was used to compare the histological features of skeletal muscle at onset with those observed at the start of the second relapse. MATERIAL AND METHODS: Histological, histochemical and ultrastructural changes, as well as biochemical oxidative damage and antioxidant-system markers, were examined in the soleus and extensor digitorum longus muscles of Dark Agouti rats in which experimental autoimmune encephalomyelitis had been induced by active immunization using myelin oligodendrocyte glycoprotein. RESULTS: Histological examination at disease onset revealed ragged-red fibers and ultrastructural evidence of mitochondrial degeneration. At the second relapse, neurogenic changes included a wide range of cytoarchitectural lesions, skeletal muscle atrophy and the appearance of intermediate fibers; however, differences were observed between soleus and extensor digitorum longus lesions. Biochemical tests disclosed an increase in oxidative stress markers at onset, which was more pronounced at the second relapse. CONCLUSIONS: Microscopic findings suggest that two patterns can be distinguished at disease onset: an initial phase characterized by muscle mitochondrial alterations, and a second phase dominated by a histological muscle pattern of clearly neurogenic origin.