Publications by authors named "G Nathan Nakken"

2 Publications

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Evaluating for a correlation between osteopathic examination and ultrasonography on thoracic spine asymmetry.

J Osteopath Med 2021 Oct 13;122(1):31-43. Epub 2021 Oct 13.

Department of Anatomy, Midwesetern University, Arizona College of Osteopathic Medicine, Glendale, AZ, USA.

Context: The thoracic spine is a common area of focus in osteopathic manipulative medicine (OMM) for a variety of conditions. Thoracic spine somatic dysfunction diagnosis is achieved by palpating for asymmetry at the tips of the transverse processes (TPs). Previous studies reveal that instead of following the rule of threes, the TPs of a given thoracic vertebra generally align with the spinous process (SP) of the vertebra above. Ultrasonography has been widely utilized as a diagnostic tool to monitor musculoskeletal conditions; it does not utilize ionizing radiation, and it has comparable results to gold-standard modalities. In the case of thoracic somatic dysfunction, ultrasound (US) can be utilized to determine the location of each vertebral TP and its relationship with the SP. Previous studies have investigated the correlation between OMM and ultrasonography of the cervical, lumbar, and sacral regions. However, there has been no study yet that has compared osteopathic structural examination with ultrasonographic examination of the thoracic vertebral region.

Objectives: To examine the relationship between osteopathic palpation and ultrasonographic measurements of the thoracic spine by creating a study design that utilizes interexaminer agreement and correlation.

Methods: The study identifier is NCT04823637. Subjects were student volunteers recruited from the Midwestern University (MWU)-Glendale campus. A nontoxic, nonpermanent marker was utilized to mark bony landmarks on the skin. Two neuromusculoskeletal board-certified physicians (OMM1, OMM2) separately performed structural exams by palpating T2-T5 TPs to determine vertebral rotation. Two sonographers (US1, US2) separately scanned and measured the distance from the tip of the SP to the adjacent TPs of the vertebral segment below. Demographic variables were summarized with mean and standard deviation. Interexaminer agreement was assessed with percent agreement, Cohen's Kappa, and Fleiss' Kappa. Correlation was measured by Spearman's rank correlation coefficient. Recruitment and protocols were approved by the MWU Institutional Review Board (IRB).

Results: US had fair interexaminer agreement for the overall most prominent segmental rotation of the T3-T5 thoracic spine, with Cohen's Kappa at 0.27 (0.09, 0.45), and a total agreement percentage at 51.5%. Osteopathic palpation revealed low interexaminer agreement for the overall most prominent vertebral rotation, with Cohen's Kappa at 0.05 (0.0, 0.27), and 31.8%. Segment-specific vertebral analysis revealed slight agreement between US examiners, with a correlation coefficient of 0.23, whereas all other pairwise comparisons showed low agreement and correlation. At T4, US had slight interexaminer agreement with 0.24 correlation coefficient, and osteopathic palpation showed low interexaminer (OMM1 vs. OMM2) agreement (0.17 correlation coefficient). At T5, there was moderate agreement between the two sonographers with 0.44 (0.27, 0.60) and 63.6%, with a correlation coefficient of 0.57, and slight agreement between OMM1 and OMM2 with 0.12 (0.0, 0.28) and 42.4%, with 0.23 correlation coefficient.

Conclusions: This preliminary study of an asymptomatic population revealed that there is a low-to-moderate interexaminer reliability between sonographers, low-to-slight interexaminer reliability between osteopathic physicians, and low interexaminer reliability between OMM palpatory examination and ultrasonographic evaluation of the thoracic spine.
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October 2021

Effects of excess corticosterone on LKB1 and AMPK signaling in rat skeletal muscle.

J Appl Physiol (1985) 2010 Feb 3;108(2):298-305. Epub 2009 Dec 3.

Dept. of Physiology and Developmental Biology, Brigham Young Univ., Provo, Utah 84602, USA.

Cushing's syndrome is characterized by marked central obesity and insulin insensitivity, effects opposite those seen with chronic AMP-activated protein kinase (AMPK) activation. This study was designed to determine whether chronic exposure to excess glucocorticoids influences LKB1/AMPK signaling in skeletal muscle. Corticosterone pellets were implanted subcutaneously in rats (hypercorticosteronemia, Hypercort) for 2 wk. Controls were sham operated and fed ad libitum or were sham operated and food restricted (pair-weighted group, Pair) to produce body weights similar to Hypercort rats. At the end of the 2-wk treatment period, rats were anesthetized, and the right gastrocnemius-plantaris (gastroc) and soleus muscles were removed. Left muscles were removed after electrical stimulation for 5 min. No significant differences were noted between treatment groups in ATP, creatine phosphate, or LKB1 activity. The alpha- and beta-subunit isoforms were not significantly influenced in gastroc by corticosterone treatment. Expression of the gamma3-subunit decreased, and gamma1- and gamma2-subunit expression increased. Both alpha2-AMPK and alpha1-AMPK activities were increased in the gastroc in response to electrical stimulation, but the magnitude of the increase was less for alpha2 in the Hypercort rats. Despite elevated plasma insulin and elevated plasma leptin in the Hypercort rats, phosphorylation of TBC1D1 was lower in both resting and stimulated muscle compared with controls. Malonyl-CoA content was elevated in gastroc muscles of resting Hypercort rats. These changes in response to excess glucocorticoids could be responsible, in part, for the decrease in insulin sensitivity and adiposity seen in Cushing's syndrome.
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February 2010