Ultrasound Measurements of the Ulnar Nerve at the Medial Epicondyle Correlate With Electrodiagnostic Studies.

BACKGROUND: Cubital tunnel syndrome is the second most common compressive neuropathy in the upper extremity and is commonly evaluated with electrodiagnostic studies (EDS). Ultrasound (US) has emerged as a potentially more efficient alternative to EDS. The purpose of this study is to evaluate whether measurements of the cross-sectional area (CSA) of the ulnar nerve at the elbow correlate with EDS results. METHODS: This study was a prospective analysis of patients who presented with signs and symptoms consistent of cubital tunnel syndrome, who received USs of the ulnar nerve at the elbow and nerve conduction tests. Pearson correlation coefficients were used to evaluate the correlation between ulnar nerve CSA and electrodiagnostic data. t Tests were used to evaluate statistical differences between the mean ulnar nerve CSA of patients with positive or negative nerve conduction study results. Youden Index was used to calculate the optimal cut-off point for US CSA based on maximal sensitivity and specificity. Statistical significance was based on a two-sided P less than .05. RESULTS: The association between increasing US CSA at the medial epicondyle with slowing of the conduction velocity of the ulnar motor nerve across the elbow was statistically significant (r = -0.35, P = .02). Patients with positive EDS tests had significantly larger nerve size than those with negative tests (all Ps < .03). A cut-off point of greater than or equal to 11 mm2 had a sensitivity of 70.83% and specificity of 66.67%. CONCLUSIONS: Larger ulnar nerve CSAs correlate with slowing of the conduction velocity on EDSs, and those with positive EDSs have larger nerve sizes than those with negative tests.

Production of nascent ribosome precursors within the nucleolar microenvironment of Saccharomyces cerevisiae.

35S rRNA transcripts include a 5'-external transcribed spacer followed by rRNAs of the small and large ribosomal subunits. Their processing yields massive precursors that include dozens of assembly factor proteins. In Saccharomyces cerevisiae, nucleolar assembly factors form 2 coaxial layers/volumes around ribosomal DNA. Most of these factors are cyclically recruited from a latent state to an operative state, and are extensively conserved. The layers match, at least approximately, known subcompartments found in higher eukaryotic cells. ∼80% of assembly factors are essential. The number of copies of these assembly factors is comparable to the number of nascent transcripts. Moreover, they exhibit "isoelectric balance," with RNA-binding candidate "nucleator" assembly factors being notably basic. The physical properties of pre-small subunit and pre-large subunit assembly factors are similar, as are their 19 motif signatures detected by hierarchical clustering, unlike motif signatures of the 5'-external transcribed spacer rRNP. Additionally, many assembly factors lack shared motifs. Taken together with the progression of rRNP composition during subunit maturation, and the realization that the ribosomal DNA cable is initially bathed in a subunit-nonspecific assembly factor reservoir/microenvironment, we propose a "3-step subdomain assembly model": Step (1): predominantly basic assembly factors sequentially nucleate sites along nascent rRNA; Step (2): the resulting rRNPs recruit numerous less basic assembly factors along with notably basic ribosomal proteins; Step (3): rRNPs in nearby subdomains consolidate. Cleavages of rRNA then promote release of rRNPs to the nucleoplasm, likely facilitated by the persistence of assembly factors that were already associated with nucleolar precursors.

Cardiorespiratory anomalies and increased brainstem microglia in a rat model of neonatal opioid withdrawal syndrome.

Infants born with neonatal opioid withdrawal syndrome (NOWS) can display abnormal cardiorespiratory patterns including tachypnea, tachycardia, and impaired ventilatory responses to hypoxia (HVR) and hypercapnia (HCVR). Chronic morphine exposure is associated with increased midbrain microglial expression. Using a rat model of pre- and post-natal morphine exposure, we assessed cardiorespiratory features of NOWS (resting tachycardia and tachypnea) including the attenuated HVR and HCVR and whether they are associated with increased brainstem microglia expression. Pregnant rats (dams) received twice-daily subcutaneous injections of morphine (5 mg/kg) during the third (last) week of pregnancy to simulate 3rd trimester in utero opioid exposure. Offspring then received once-daily subcutaneous injections of morphine (0.5 mg/kg) until postnatal (P) day P10 days of age to simulate postnatal morphine therapy. Cardiorespiratory responses were assessed 24 h later (P11 days) following spontaneous withdrawal. Compared to saline-treated pups, morphine-exposed offspring exhibited tachycardia and tachypnea as well as an attenuated HVR and HCVR. Microglial cell counts were increased in the nucleus tractus solitarius (nTS), dorsal motor nucleus of the vagus (DMNV) and nucleus ambiguous (NAamb), but not the retrapezoid nucleus (RTN) or the non-cardiorespriatory region, the cuneate nucleus (CN). These data suggest that the cardiorespiratory features and autonomic dysregulation in NOWS infants may be associated with altered microglial function in specific brainstem cardiorespiratory control regions.