Metagenomics analysis reveals universal signatures of the intestinal microbiota in colorectal cancer, regardless of regional differences

The human gut microbiota is a complex and dynamic community of microorganisms living in our intestines and has emerged as an important factor for colorectal adenocarcinoma (CRC). The purpose of our study was to investigate the microbiota composition in Brazilian CRC patients compared with a local control population (CTL) to find out which changes could be considered universal or regional features in CRC microbiota. Fecal samples were obtained from 28 CRC and 23 CTL individuals. The 16S rRNA gene was used for metagenomic analysis. In addition to the anthropometric variables, the clinical stage (TNM 2018) was considered. Patients with CRC had a significant increase in alpha diversity and a higher percentage of genus Prevotella and a decreased proportion of Megamonas and Ruminococcus. Additionally, the proportion of Faecalibacterium prausnitzii was associated with a better prognosis in the first stages of CRC, and Fusobacterium nucleatum proved to be an important marker of colorectal carcinogenesis and tumor aggressiveness. Although regional differences influence the composition of the microbiota, in the case of CRC, the microhabitat created by the tumor seems to be a major factor. Our results contribute to a better understanding of the carcinogenic process, and even in different environments, some factors appear to be characteristic of the microbiota of patients with CRC.

Unusual relationship between the piriform muscle and sciatic, inferior gluteal and posterior femoral cutaneous nerves / Relación inusual entre el músculo piriforme y los nervios isquiático, glúteo inferior y cutâneo femoral posterior

Piriformis muscle syndrome has been increasingly recognized as a cause of leg pain. Overuse, strain, or anatomical variations of the relationship between the nerve and the piriformis muscle are thought to be the underlying causes of the entrapment of the sciatic nerve. We report a variation not previously described which was found during a routine dissection. During routine dissection of the left gluteal region of an adult male cadaver we observed a high division of the sciatic nerve and the presence of an accessory piriformis muscle. The sciatic nerve divided beneath the piriformis muscle and the common fibular nerve passed over the accessory piriformis muscle, whereas the tibial nerve reflected anteriorly to pass between the accessory piriformis and the superior gemellus muscle. Additionally, both nerves communicated with a side branch under the inferior border of the accessory piriformis muscle and the inferior gluteal nerve originated from the fibular nerve. Anatomical variations in the relationship between the piriformis muscle and the sciatic nerve may be present in up to 17% of the population. Six different variations have been described and none of them is similar to our description. Though complete understanding of the physiopathology of the piriformis muscle syndrome remains to be elucidated, knowledge of the possible anatomical variations may be useful for its adequate diagnosis and treatment.

El síndrome del músculo piriforme se ha reconocido cada vez más como una causa de dolor en los miembros inferiores. Tensión excesiva o variaciones anatómicas del nervio y del músculo piriforme se cree son las causas subyacentes de pinzamiento del nervio isquiático. Se presenta una variación no descrita anteriormente. Durante una disección de rutina en un cadáver de sexo masculino, se observó una división más alta del nervio isquiático y la presencia de un músculo piriforme accesorio. El nervio isquiático se dividía bajo el músculo piriforme y el nervio fibular común pasaba sobre el músculo piriforme accesorio. Por otra parte, el nervio tibial cruzaba entre los músculos piriforme accesorio y gemelo superior. Además, ambos nervios se comunicaban con un ramo lateral bajo el margen inferior del músculo piriforme accesorio y el nervio glúteo inferior se originaba desde el nervio fibular. Variaciones anatómicas y relaciones entre el músculo piriforme y nervio isquiático pueden estar presentes hasta en el 17% de la población. Seis variaciones diferentes se han descrito en este artículo y ninguna es similar a nuestra descripción. A pesar del completo entendimiento de la fisiopatología del síndrome del músculo piriforme, aún queda por esclarecer y conocer las posibles variaciones anatómicas que pueden ser útiles tanto para su diagnóstico como para el tratamiento adecuado.

A rare pattern of brachial artery variation: case report / Un patrón de variación raro de la arteria braquial: reporte de caso

Unlike the venous system, variations in arterial anatomy are less frequent and most of them affect visceral arteries. In limbs, variations of the brachial artery are the most reported and at least six different patterns have been described so far. The commonest is the superficial brachial artery which lies superficially to the median nerve. Much less prevalent are the high origin of the radial artery (brachioradial artery) or the existence of a doubled brachial artery (accessory brachial artery). We present a previously undescribed pattern of brachial artery variation. During dissection of the right upper limb of a 60 year-old male embalmed cadaver, we found the bifurcation of the brachial artery in the proximal portion of the middle third of the arm. Its medial branch reaches the medial aspect of the arm, posterior to the median nerve. Afterwards, this medial branch redirects laterally and crosses again the median nerve, this time lying anterior to the nerve until it reaches the lateral aspect of the arm. At the elbow level, the medial branch originates the radial artery. The lateral branch of the brachial artery remains lateral to the median nerve and continues as ulnar artery and originates the interosseus artery.

A diferencia del sistema venoso, las variaciones en la anatomía arterial son menos frecuentes y la mayoría afecta a las arterias viscerales. En los miembros, las variaciones de la arteria braquial son las más informadas y por lo menos seis diferentes patrones han sido descritos. La variación más común es de la arteria braquial superficial que está superficialmente al nervio mediano. Mucho menos frecuente es el origen alto de la arteria braquial radial (la arteria braquiorradial) o la existencia de una arteria braquial doble (arteria braquial accesoria). Presentamos un patrón de variación no descrito de la arteria braquial observado durante la disección del miembro superior derecho de un cadáver en un hombre de 60 años de edad. Encontramos la bifurcación de la arteria braquial en la porción medial del brazo, pasando posterior al nervio mediano. Luego, esta rama medial se redirecciona lateralmente y cruza nuevamente al nervio mediano, esta vez, anterior a él, hasta alcanzar la región lateral del brazo. A nivel de la flexura del codo, la rama medial origina la arteria radial. La rama lateral de la arteria braquial se mantiene lateral al nervio mediano y continúa como arteria ulnar y origina la arteria interósea común.