Laboratory Research
This section includes Class of 2023 Embark Projects within the Laboratory & Bench research disciplines. These projects include traditional bench research in a variety of basic and clinical science areas.
Comparing Mutability of Clinically Significant Voltage-Gated Sodium Channel Subunits
Ian Armstrong, B.S.1, Gustavo Patino, M.D. / Ph.D.2
1Oakland University William Beaumont School of Medicine, Rochester, Michigan
2Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, Michigan
INTRODUCTION
The objective of this project was to compare the mutability profile of the clinically significant beta1 and beta2 subunits of the voltage-gated sodium channel. The voltage-gated sodium channel (VGSC) plays a role in generating action potentials in excitable tissues. Mutations in VGSC subunits, including the beta1 and beta3 subunits, are associated with diseases like epilepsy and cardiac arrhythmia.
METHODS
We compared amino acid variants in the beta1 and beta2 subunits found in patients and the general population within the gnomAD database, and cancer cell variants from the cBioPortal Cancer Genomics database. We also reviewed variants for both subunits in cancer cells using the cBioPortal database.
RESULTS
Based on the data from gnomAD both subunits have variants reported in a similar percentage of the primary sequence (39.4% for beta1 and 39% for beta3), but pathogenic variants are more common in beta1 (5% of residues) than beta3 (1.86%, p=0.065). In 43789 patients with sequencing information for the genes SCN1B and SCN3B (coding for beta1 and beta3, respectively) 2.2% had non-synonymous variants in beta1 and 3.3% in beta3 (p=0.002). A minority of residues within each subunit (6.8% in beta1 and 9.76% in beta3) had a variant reported in cancer cells (p=.276). 4.58% of beta1 and 6.51% of beta3 residues have variants reported both in human and cancer cells. Of the residues reported with pathogenic variants in beta1, one (p.C21) had a variant found in cancer cells, and there were none for beta3.
CONCLUSIONS
Our results suggest that residues with pathogenic variants are a non- overlapping set between the two subunits, and might represent targets for their specialized function. In cancer cells, beta3 had a higher mutation load than beta1, suggesting different evolutionary pressures on both proteins. One limitation of our study is that we only focused on the main splice variant of SCN1B and SCN3B genes.
Surveillance of Dual-Mobility Hip Systems: Damage Mode and Clinical Data Analysis
Camilla Cascardo, B.S.1, Conner D. Ahlgren, M.D.2, Michael J. Maxwell, M.D.2, Tyler Vovos, M.D.2, Mark Karadsheh, M.D.2, Drew Moore, M.D.2
1Oakland University William Beaumont School of Medicine, Rochester, Michigan
2Department of Orthopedic Surgery, Beaumont Health, Royal Oak, Michigan
INTRODUCTION
Hip instability following total hip arthroplasty (THA) is a prominent indication for revision surgery. Dual mobility (DM) implants are designed to increase stability, and trending use makes characterizing in vivo damage and clinical failure modes important. This study expounds upon micro- and macroscopic damage mode findings of Lombardo et al., including novel screw ring damage using an updated retrieval registry.
METHODS
Under an institutional review board approved implant retrieval protocol, 51 DM THA systems were analyzed. Components were examined for standard damage modes and graded for fretting and corrosion following the Goldberg et al. classification system. Clinically-relevant data were collected from medical records. Analysis was completed using Spearman rank order correlation and Mann-Whitney U-tests, with p < 0.05.
RESULTS
The average duration of implantation was 12 months, which correlated with summed femoral head corrosion (p=0.044). Top reasons for revision included mechanical complications (n=15, 27%), infection (n=12, 22%), and dislocation (n=9, 16%). Average summed fretting and corrosion scores were 2.9 and 3.0 for heads (2-8 summed scores possible), and 7.6 and 7.1 for stems (4-16 summed scores possible), respectively. Scratching (n=26, 65.4%) was the most common standard damage mode on articular surfaces of acetabular cups, burnishing (n=29, 55.2%) on metal inserts, and edge deformation (n=22, 45.5%) on polyethylene liners. Screw ring damage was noted on 10.34% (n=3) of metal inserts; increased incidence of acetabular and femoral osteolysis correlated with this damage mode (P=0.019 and P=0.022, respectively).
CONCLUSIONS
This series demonstrated damage following short-to-midterm implantation in DM THA. Fretting and corrosion scores were mild-to-moderate with a significant increase in femoral head corrosion with longer implantation and trunnion fretting and corrosion in the setting of infection. Screw ring damage may be related to acetabular and femoral osteolysis. Though limited by sample size, this study indicates trends that merit further evaluation.
A Diet High in Fat and Fructose Induces Early Hepatic Mitochondrial Aging
Rohun Gupta, B.A.1, Rohit Kohli, MBBS, MS2, Jashdeep Bhatacharjee, Ph.D.2, Rosa-Maria Salazar Gonzalez, Ph.D.2, Kristin S. Bramlage, M.D.3, Michelle Kirby, M.S.3, Andriy Myronovych M.D./Ph.D.3 , Stavra Xanthakos, M.D.3, Kevin Bove, M.D.3
1Oakland University William Beaumont School of Medicine, Rochester, Michigan
2Children's Hospital Los Angeles, Los Angeles, California
3Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
INTRODUCTION
Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are recognized as one of the leading causes of liver transplantation in the US. While the molecular mechanism behind NASH is not fully understood, studies suggest that mitochondrial dysfunction and endoplasmic reticulum (ER) stress may play an important role in the progression of the disease. Furthermore, elucidation of such changes has the potential to uncover mechanisms in the development of NASH.
METHODS
C57Bl/6 mice were randomized to a Chow (C) or high-fat, high-fructose (HF2) diet for 8, 16, or 32 weeks. The mice were weighed once a week until it was time for sacrifice. During sacrifice, blood and liver were collected in order to evaluate histology through electron microscopy, DNA content, and gene expression by qRT-PCR. All results are reported as mean ± standard error. Statistical significant differences (p<0.05) were identified using a one-way analysis of variance (ANOVA).
RESULTS
HF2 mice gained more weight and had higher fasting glucose levels. Liver triglycerides and ALT concentration increased progressively in the HF2 diet from 8 to 32 weeks. At 32 weeks 80% of the HF2 mice had hepatic fibrosis. Mice that were fed the HF2 diet had higher expression of hepatic ER stress markers compared to that of chow fed mice. In addition, there is a steep decrease in hepatic mitochondrial DNA content at 8 weeks for HF2 mice compared to chow mice. Lastly, the surface area of hepatic mitochondria decreased rapidly and inconsistently for HF2 mice.
CONCLUSIONS
HF2 mice demonstrate persistent decreases in mitochondrial DNA while developing histologic findings consistent with NASH. The results support that mitochondrial dysfunction is associated with NAFLD onset and accelerates the progression of NASH. Given that mitochondrial dysfunction is a known sign of cellular aging, we conclude that NAFLD/NASH may accelerate the progression of changes associated with hepatocyte aging.
Phenotype characterization of genetic murine mouse models of developmental dysplasia of the hip (DDH)
Stephanie Mrowczynski, B.S.1, Kevin Baker, Ph.D.2, Michael Newton, Ph.D.2
1Oakland University William Beaumont School of Medicine, Rochester, Michigan
2Department of Orthopedic Surgery, Beaumont Health
INTRODUCTION
Developmental dysplasia of the hip (DDH) is a congenital hip alteration that changes the “ball in socket” movement of the leg inside the pelvis. Genome-wide association studies have identified CX3CR1 polymorphisms associated with increased risk of Developmental Dysplasia of the Hip. Mouse models of CX3CR1 knock-out (KO) mice show unilateral, bony discrepancies between the femur head and acetabulum in comparison to wild-type (WT) mice, as well as gait impairment similar to that of humans with osteoarthritis (which develops in DDH patients later in life). The primary goal of this project is to assess joint congruity in a CX3CR1 KO model of unilateral developmental dysplasia of the hip and control populations via microcomputed tomography. The secondary goal is to evaluate bone and joint characteristics in CX3CR1 KO model of unilateral developmental dysplasia of the hip and control populations via microcomputed tomography.
METHODS
42 mice were divided into two groups based on their genotypes; 19 wild-type offspring; 23 CX3CR1 -/- offspring. Whole body and hip-focused microCT scans using a Viva80-CT (Scanco USA) were performed with a resolution of 15 micron (isotropic voxel size). Joint congruity was assessed using contralateral limbs from wild-type controls to create an “average atlas” of normal mouse joint morphology. This average atlas was used to quantify the difference in Cervico-diaphyseal angle (CDA) in CX3CR1 knock-out vs wild-type mice via MatLab application.
RESULTS
A two-sample t-test was performed to compare the mean Cervico-diaphyseal angles (CDA) in CX3CR1 knock-out vs wild-type mice. There was not a statistically significant difference between the mean left limb angles (t(40)=2.215, p=0.399), right limb angles (t(40)=2.423, p=0.754), and limb average angles (t(40)=1.927, p=0.770).
CONCLUSIONS
Investigation of other acetabular and hip joint variables, such as acetabular angle, should be considered in further characterization studies of the CX3CR1 KO mouse model.
Hip Osteoarthritis Pain Has Specific Deleterious Effects on Postural Sway Control
Skyler Porcaro, B.A.1, Luke Fickenworth, B.S.1, Daniel Goble, Ph.D.2, Joshua Haworth, Ph.D.2
1Oakland University William Beaumont School of Medicine, Rochester, Michigan
2Department of Human Movement Science, School of Health Science, Oakland University, Rochester, Michigan
INTRODUCTION
Hip osteoarthritis (hOA), is a major joint disorder that leads to decreased mobility and increased falls. However, the relationship between hOA pain, postural sway control, and falls risk is not completely understood. We present four studies exploring normative data pertaining to Limits of Stability (LOS) in a general population, markerless techniques for LOS data acquisition, relationships between LOS and disposition towards vigorous effort, and the empathy gap between patients and providers, all of which broaden our knowledge of the methodologies that can be utilized to further study individuals with hOA.
METHODS
- Normative data was created using the BTrackS LOS protocol (n=800), wherein participants were asked to sway maximally while standing on the force plate.
- Reliability of joint angles from markered and markerless tracking of LOS was tested (n=15).
- Relationship between PRETIE-Q, Grit-8, TKI, and LOS were tested (n=15).
- Exercise disposition (frequency self-report & PRETIE-Q) and provider expectations (mWOMAC) of an hOA patient’s pain, stiffness, and physical function were evaluated (n=34).
RESULTS
- Normative values were determined.
- Moderate to very high correlation was shown between marker and markerless tracking.
- Tolerance and compromising traits correlated with LOS performance.
- Providers expected severe pain, stiffness, and functional limitation. Disposition and expectations were not correlated.
CONCLUSIONS
Despite COVID-19-related restrictions, we completed four studies that broaden knowledge and future methodologies. Normative values allow increased understanding of dynamic posture. Markerless tracking allows for virtual data collection. Tolerance and compromising personality impact dynamic postural sway assessment. Empathy mismatch impacts patient care. A better understanding of postural sway control in individuals with hOA could help to recognize falls risk and reduce their occurrence. Clinical assessment of dynamic postural sway appears to be available, objective, and highly meaningful to patient-centered physical medicine.
