A broad and variable lumbosacral myotome map uncovered by foraminal nerve root stimulation.

OBJECTIVE: The human myotome is fundamental to the diagnosis and treatment of neurological disorders. However, this map was largely constructed decades ago, and its breadth, variability, and reliability remain poorly described, limiting its practical use. METHODS: The authors used a novel method to reconstruct the myotome map in patients (n = 42) undergoing placement of dorsal root ganglion electrodes for the treatment of chronic pain. They electrically stimulated nerve roots (n = 79) in the intervertebral foramina at T12-S1 and measured triggered electromyography responses. RESULTS: L4 and L5 stimulation resulted in quadriceps muscle (62% and 33% of stimulations, respectively) and tibialis anterior (TA) muscle (25% and 67%, respectively) activation, while S1 stimulation resulted in gastrocnemius muscle activation (46%). However, L5 and S1 both resulted in abductor hallucis (AH) muscle activation (17% and 31%), L5 stimulation resulted in gastrocnemius muscle stimulation (42%), and S1 stimulation in TA muscle activation (38%). The authors also mapped the breadth of the myotome in individual patients, finding coactivation of adductor and quadriceps, quadriceps and TA, and TA and gastrocnemius muscles under L3, L4, and both L5 and S1 stimulation, respectively. While the AH muscle was commonly activated by S1 stimulation, this rarely occurred together with TA or gastrocnemius muscle activation. Other less common coactivations were also observed throughout T12-S1 stimulation. CONCLUSIONS: The muscular innervation of the lumbosacral nerve roots varies significantly from the classic myotome map and between patients. Furthermore, in individual patients, each nerve root may innervate a broader range of muscles than is commonly assumed. This finding is important to prevent misdiagnosis of radicular pathologies.

Flexible pri-miRNA structures enable tunable production of 5' isomiRs.

The Drosha cleavage of a pri-miRNA defines mature microRNA sequence. Drosha cleavage at alternative positions generates 5' isoforms (isomiRs) which have distinctive functions. To understand how pri-miRNA structures influence Drosha cleavage, we performed a systematic analysis of the maturation of endogenous pri-miRNAs and their variants both in vitro and in vivo. We show that in addition to previously known features, the overall structural flexibility of pri-miRNA impact Drosha cleavage fidelity. Internal loops and nearby G · U wobble pairs on the pri-miRNA stem induce the use of non-canonical cleavage sites by Drosha, resulting in 5' isomiR production. By analysing patient data deposited in the Cancer Genome Atlas, we provide evidence that alternative Drosha cleavage of pri-miRNAs is a tunable process that responds to the level of pri-miRNA-associated RNA-binding proteins. Together, our findings reveal that Drosha cleavage fidelity can be modulated by altering pri-miRNA structure, a potential mechanism underlying 5' isomiR biogenesis in tumours.[Figure: see text].

Reporting of Research by Matched Otolaryngology Residency Applicants.

OBJECTIVES: Matching to an otolaryngology residency program is a competitive process for medical students, and research performed by students is considered as a factor for granting interviews by program directors. Because abstracts, presentations and publications are all reported in combination by the National Resident Matching Program's "Charting Outcomes in the Match" (ChOM) and may be weighted differently by PDs, we specifically investigated the number of publications by past applicants accepted to top otolaryngology residency programs. METHODS: The top 25 otolaryngology residency programs were identified using Doximity, sorting by reputation. Current residents were determined from the programs' websites. Using PubMed, each resident's number of publications, authorship status, and journal type were recorded. RESULTS: A total of 24 programs were included in the final analysis and the average number of manuscripts was 2.76 ± 4.01. The mean number of publications in otolaryngology journals was 1.03 ± 1.91. CONCLUSIONS: The difference between the investigated average number of publications (2.76) and those published by ChOM (10.4) represent a discrepancy due to the lack of delineation between abstracts, presentations and publications. The reported numbers for research may lead medical students to pursue alternate measures to increase their own research. Some options, such as adding a research year are not universally accessible. A clearer and more detailed approach to reporting research statistics would be beneficial to both applicants and PDs for otolaryngology programs.