Alex spencer - Academia.edu (original) (raw)

Papers by Alex spencer

Australian Historical Studies

Irish Economic and Social History, 2013

American National Biography Online, 2000

American National Biography Online, 2000

Recovery from anterior cruciate ligament reconstruction (ACLR) commonly results in undesirable ph... more Recovery from anterior cruciate ligament reconstruction (ACLR) commonly results in undesirable physical and patient-reported outcomes (PROs). Identification of modifiable factors such as knee contact force (KCF) early in rehabilitation that can improve these outcomes is important due to the rapid decrease in function, quality of life, and joint health in this population. Additionally, if noninvasive measurement of KCFs outside of a traditional laboratory were possible, clinicians could optimize patient treatment with personalized care. Therefore, there are two primary aims to this thesis: 1) quantify the link between KCF and PROs which measure pain, ability to perform activities of daily living, and quality of life 6 months after ACLR; and 2) develop a novel method to monitor KCF outside the laboratory using unobtrusive wearable sensors. To address the first aim, eighty subjects were enrolled six months following ACLR. Patient-reported quality of life, ability to perform activities of daily living, and pain were evaluated with the KOOS QOL, ADL, and Pain subscales, respectively. A musculoskeletal model was utilized to estimate peak KCF. Subjects with scores above the patient acceptable symptom state (PASS) threshold for the KOOS QOL and ADL demonstrated greater ACLR limb peak KCF (p = 0.001 and p = 0.017, respectively), which was not found with KOOS Pain-dichotomized groups (p = 0.079). To address the second aim, nine healthy subjects walked at a wide range of speeds on an instrumented treadmill. Thirteen insole force features were calculated as potential predictors of peak KCF and KCF impulse per step, estimated with musculoskeletal modeling. Prediction error was calculated as 10-fold cross validated median symmetric accuracy. Pearson product-moment correlation coefficients defined the relationship between variable pairs. Models developed per-limb demonstrated lower prediction error (KCF impulse: 2.19%; peak KCF: 3.50%) than those developed per-subject (KCF impulse: 3.40%; peak KCF: 6.47%). A number of insole fe [...]

Physical Therapy, 2021

Objective Disability is common after lower extremity fracture (LEF). Although psychosocial factor... more Objective Disability is common after lower extremity fracture (LEF). Although psychosocial factors have been associated with patient-reported outcomes after LEF, they have not been associated with objective measures of function. Aberrant gait patterns are important markers of function, but are poorly defined after LEF. The primary purpose of this study was to explore whether pain catastrophizing and fear of movement 6 weeks after surgery were associated with injured limb loading outcomes and 6-minute walk test (6MWT) distance 12 months after femur or tibia fracture. The secondary purpose was to determine if limb loading characteristics differed between injured and uninjured limbs. Methods At 6 weeks after LEF, patients completed validated measures of pain catastrophizing, fear of movement, and depression. At 12 months, patients completed a 6MWT while wearing instrumented insoles that recorded the limb loading outcomes of stance time, impulse, and loading rate. Bivariate correlations...

The American Surgeon, 2019

Trauma in pregnancy is a leading cause of poor fetal and obstetric outcomes. Trauma team activati... more Trauma in pregnancy is a leading cause of poor fetal and obstetric outcomes. Trauma team activation (TTA) criteria include injury with ≥ 20 weeks gestational age (GA). A retrospective analysis was performed on pregnant patients evaluated at a Level 1 trauma center. Patients were characterized by TTA: full, partial, or non-TTA, and TTA criteria independent of pregnancy. Index trauma and delayed delivery hospitalization outcomes were examined. Bivariate analysis, t test, and logistic regression were used when appropriate. From 2010 to 2015, 216 full, 50 partial, and 50 non-TTAs presented. Independent of pregnancy, 79 per cent of patients did not meet the TTA criteria. Fourteen (4%) had a pregnancy-related complication during index hospitalization (eight fetal and two maternal deaths). Nine of ten deaths occurred in patients meeting TTA independent of pregnancy. Delivery complications were greater in the index (52%, 13/25) versus subsequent (5%, 17/155) hospitalizations and were predic...

Medicine & Science in Sports & Exercise, 2020

Repetitive lifting with submaximal loads has gained popularity as a mean for increasing strength ... more Repetitive lifting with submaximal loads has gained popularity as a mean for increasing strength and endurance. Given that repetitive lifting is a known occupational risk factor for low back injury, it is important to develop an objective criterion for determination of number of lifting repetitions that maximize the benefits of lifting, while minimizing the potential risk for low back injuries. PURPOSE: To determine whether measures of lumbo-pelvic coordination (LPC) during repetitive low-handle hexagonal bar deadlift (LHBD) get impaired before lifter exhaustion. METHODS: Eight weight-trained males performed repetitions-to-fatigue of LHBD with a load of 68 kg. Rotations of the thorax and pelvis in the sagittal plane, measured using a motion capture system, were used to characterize LPC according to Needham, et al. 2015. Subsequently, the differences in LPC over the early portion of the lifting phase between the first and last 10% of total lifting repetitions were compared using paired to-tests. RESULTS: Peak pelvic and trunk flexion angles and lumbar range of rotation from respective values of 53.9° ± 4.8°, 64.9° ± 6.6°, and 28.8° ± 3.2° during the first 10% of lifting cycles increased to 57.2° ± 4.1° (p = 0.02) 69.4° ± 6.7° (p = 0.05), and 32.9° ± 5.2° (p = 0.04) during the last 10%. Pelvic and trunk rotations over the early portion of the lifting phase were in-phase (anti-phase) 40.0% ± 8.8% (21.3% ± 2.8%) of the time during the first 10% of lifting cycles that increased, p=0.04, (decreased, p=0.01) to 47.9% ± 4.8% (12.4% ± 4.9%) during the last 10% of lifting cycles. CONCLUSION: Significant changes in neuromuscular control of LPC were observed before participants stop lifting due to fatigue. Such alterations in LPC changes mechanical loads experienced in the spinal tissues, hence, affecting risk of injury. However, more research is needed to understand the impact of such impairments in LPC on spinal loads and risk of injury.

Medicine & Science in Sports & Exercise, 2018

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged in December 20191,2 and is r... more Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged in December 20191,2 and is responsible for the COVID-19 pandemic3. Vaccines are an essential countermeasure urgently needed to control the pandemic4. Here, we show that the adenovirus-vectored vaccine ChAdOx1 nCoV-19, encoding the spike protein of SARS-CoV-2, is immunogenic in mice, eliciting a robust humoral and cell-mediated response. This response was not Th2 dominated, as demonstrated by IgG subclass and cytokine expression profiling. A single vaccination with ChAdOx1 nCoV-19 induced a humoral and cellular immune response in rhesus macaques. We observed a significantly reduced viral load in bronchoalveolar lavage fluid and respiratory tract tissue of vaccinated animals challenged with SARS-CoV-2 compared with control animals, and no pneumonia was observed in vaccinated rhesus macaques. Importantly, no evidence of immune-enhanced disease following viral challenge in vaccinated animals was observed. ChAdOx1 nCoV-...

Blood, 2007

A major signaling pathway that regulates platelet shape change and reorganization of the cytoskel... more A major signaling pathway that regulates platelet shape change and reorganization of the cytoskeleton involves the Rho family of GTPases whose members include Rac, CDC42 and RhoA. These GTPases are converted from their inactive or GDP-loaded state to the active or GTP-loaded state by a class of enzymes called Guanine-nucleotide Exchange Factors (GEFs). GEFs are a family of multi-domain proteins that contain a GDP-GTP exchange domain (DH-PH) as well as other protein interacting domains that are regulated by the activation of receptors present on the platelet surface. We used an affinity binding technique followed by mass spectrometry analysis to identify novel Rac binding GEFs from platelet lysates. Recombinant GST-Rac fusion proteins bound to agarose beads were prepared in the GTP, GDP and nucleotide-free states and incubated with human platelet lysates. Platelet lysate proteins associated with the different GST-Rac preparations (GTP-bound, GDP-bound or nucleotide-free) were eluted ...

Blood, 2008

A major signaling pathway that regulates platelet shape change and reorganization of the cytoskel... more A major signaling pathway that regulates platelet shape change and reorganization of the cytoskeleton involves the Rho family of GTPases; CDC42 (fillapodia), Rac1 (lamellapodia) and RhoA (focal adhesions). These GTPases are converted from their inactive or GDP-loaded state to the active or GTP-loaded state by a class of enzymes called Guanine Exchange Factors (GEFs). GEFs are a family of multi-domain proteins that contain a GDP-GTP exchange domain (DH-PH) as well as other protein interacting domains that are regulated by the activation of receptors present on the platelet surface. We used an affinity binding technique followed by mass spectroscopy to identify novel Rho family binding GEFs in platelet lysates. Recombinant GST-Rho fusion proteins bound to agarose beads were prepared in the GTP, GDP and nucleotide-free states and incubated with clarified human platelet lysates. Platelet lysate proteins associated with the different GST-Rho preparations were eluted and run on SDS-PAGE. ...

Clinical Biomechanics, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Australian Historical Studies

Irish Economic and Social History, 2013

American National Biography Online, 2000

American National Biography Online, 2000

Recovery from anterior cruciate ligament reconstruction (ACLR) commonly results in undesirable ph... more Recovery from anterior cruciate ligament reconstruction (ACLR) commonly results in undesirable physical and patient-reported outcomes (PROs). Identification of modifiable factors such as knee contact force (KCF) early in rehabilitation that can improve these outcomes is important due to the rapid decrease in function, quality of life, and joint health in this population. Additionally, if noninvasive measurement of KCFs outside of a traditional laboratory were possible, clinicians could optimize patient treatment with personalized care. Therefore, there are two primary aims to this thesis: 1) quantify the link between KCF and PROs which measure pain, ability to perform activities of daily living, and quality of life 6 months after ACLR; and 2) develop a novel method to monitor KCF outside the laboratory using unobtrusive wearable sensors. To address the first aim, eighty subjects were enrolled six months following ACLR. Patient-reported quality of life, ability to perform activities of daily living, and pain were evaluated with the KOOS QOL, ADL, and Pain subscales, respectively. A musculoskeletal model was utilized to estimate peak KCF. Subjects with scores above the patient acceptable symptom state (PASS) threshold for the KOOS QOL and ADL demonstrated greater ACLR limb peak KCF (p = 0.001 and p = 0.017, respectively), which was not found with KOOS Pain-dichotomized groups (p = 0.079). To address the second aim, nine healthy subjects walked at a wide range of speeds on an instrumented treadmill. Thirteen insole force features were calculated as potential predictors of peak KCF and KCF impulse per step, estimated with musculoskeletal modeling. Prediction error was calculated as 10-fold cross validated median symmetric accuracy. Pearson product-moment correlation coefficients defined the relationship between variable pairs. Models developed per-limb demonstrated lower prediction error (KCF impulse: 2.19%; peak KCF: 3.50%) than those developed per-subject (KCF impulse: 3.40%; peak KCF: 6.47%). A number of insole fe [...]

Physical Therapy, 2021

Objective Disability is common after lower extremity fracture (LEF). Although psychosocial factor... more Objective Disability is common after lower extremity fracture (LEF). Although psychosocial factors have been associated with patient-reported outcomes after LEF, they have not been associated with objective measures of function. Aberrant gait patterns are important markers of function, but are poorly defined after LEF. The primary purpose of this study was to explore whether pain catastrophizing and fear of movement 6 weeks after surgery were associated with injured limb loading outcomes and 6-minute walk test (6MWT) distance 12 months after femur or tibia fracture. The secondary purpose was to determine if limb loading characteristics differed between injured and uninjured limbs. Methods At 6 weeks after LEF, patients completed validated measures of pain catastrophizing, fear of movement, and depression. At 12 months, patients completed a 6MWT while wearing instrumented insoles that recorded the limb loading outcomes of stance time, impulse, and loading rate. Bivariate correlations...

The American Surgeon, 2019

Trauma in pregnancy is a leading cause of poor fetal and obstetric outcomes. Trauma team activati... more Trauma in pregnancy is a leading cause of poor fetal and obstetric outcomes. Trauma team activation (TTA) criteria include injury with ≥ 20 weeks gestational age (GA). A retrospective analysis was performed on pregnant patients evaluated at a Level 1 trauma center. Patients were characterized by TTA: full, partial, or non-TTA, and TTA criteria independent of pregnancy. Index trauma and delayed delivery hospitalization outcomes were examined. Bivariate analysis, t test, and logistic regression were used when appropriate. From 2010 to 2015, 216 full, 50 partial, and 50 non-TTAs presented. Independent of pregnancy, 79 per cent of patients did not meet the TTA criteria. Fourteen (4%) had a pregnancy-related complication during index hospitalization (eight fetal and two maternal deaths). Nine of ten deaths occurred in patients meeting TTA independent of pregnancy. Delivery complications were greater in the index (52%, 13/25) versus subsequent (5%, 17/155) hospitalizations and were predic...

Medicine & Science in Sports & Exercise, 2020

Repetitive lifting with submaximal loads has gained popularity as a mean for increasing strength ... more Repetitive lifting with submaximal loads has gained popularity as a mean for increasing strength and endurance. Given that repetitive lifting is a known occupational risk factor for low back injury, it is important to develop an objective criterion for determination of number of lifting repetitions that maximize the benefits of lifting, while minimizing the potential risk for low back injuries. PURPOSE: To determine whether measures of lumbo-pelvic coordination (LPC) during repetitive low-handle hexagonal bar deadlift (LHBD) get impaired before lifter exhaustion. METHODS: Eight weight-trained males performed repetitions-to-fatigue of LHBD with a load of 68 kg. Rotations of the thorax and pelvis in the sagittal plane, measured using a motion capture system, were used to characterize LPC according to Needham, et al. 2015. Subsequently, the differences in LPC over the early portion of the lifting phase between the first and last 10% of total lifting repetitions were compared using paired to-tests. RESULTS: Peak pelvic and trunk flexion angles and lumbar range of rotation from respective values of 53.9° ± 4.8°, 64.9° ± 6.6°, and 28.8° ± 3.2° during the first 10% of lifting cycles increased to 57.2° ± 4.1° (p = 0.02) 69.4° ± 6.7° (p = 0.05), and 32.9° ± 5.2° (p = 0.04) during the last 10%. Pelvic and trunk rotations over the early portion of the lifting phase were in-phase (anti-phase) 40.0% ± 8.8% (21.3% ± 2.8%) of the time during the first 10% of lifting cycles that increased, p=0.04, (decreased, p=0.01) to 47.9% ± 4.8% (12.4% ± 4.9%) during the last 10% of lifting cycles. CONCLUSION: Significant changes in neuromuscular control of LPC were observed before participants stop lifting due to fatigue. Such alterations in LPC changes mechanical loads experienced in the spinal tissues, hence, affecting risk of injury. However, more research is needed to understand the impact of such impairments in LPC on spinal loads and risk of injury.

Medicine & Science in Sports & Exercise, 2018

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged in December 20191,2 and is r... more Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged in December 20191,2 and is responsible for the COVID-19 pandemic3. Vaccines are an essential countermeasure urgently needed to control the pandemic4. Here, we show that the adenovirus-vectored vaccine ChAdOx1 nCoV-19, encoding the spike protein of SARS-CoV-2, is immunogenic in mice, eliciting a robust humoral and cell-mediated response. This response was not Th2 dominated, as demonstrated by IgG subclass and cytokine expression profiling. A single vaccination with ChAdOx1 nCoV-19 induced a humoral and cellular immune response in rhesus macaques. We observed a significantly reduced viral load in bronchoalveolar lavage fluid and respiratory tract tissue of vaccinated animals challenged with SARS-CoV-2 compared with control animals, and no pneumonia was observed in vaccinated rhesus macaques. Importantly, no evidence of immune-enhanced disease following viral challenge in vaccinated animals was observed. ChAdOx1 nCoV-...

Blood, 2007

A major signaling pathway that regulates platelet shape change and reorganization of the cytoskel... more A major signaling pathway that regulates platelet shape change and reorganization of the cytoskeleton involves the Rho family of GTPases whose members include Rac, CDC42 and RhoA. These GTPases are converted from their inactive or GDP-loaded state to the active or GTP-loaded state by a class of enzymes called Guanine-nucleotide Exchange Factors (GEFs). GEFs are a family of multi-domain proteins that contain a GDP-GTP exchange domain (DH-PH) as well as other protein interacting domains that are regulated by the activation of receptors present on the platelet surface. We used an affinity binding technique followed by mass spectrometry analysis to identify novel Rac binding GEFs from platelet lysates. Recombinant GST-Rac fusion proteins bound to agarose beads were prepared in the GTP, GDP and nucleotide-free states and incubated with human platelet lysates. Platelet lysate proteins associated with the different GST-Rac preparations (GTP-bound, GDP-bound or nucleotide-free) were eluted ...

Blood, 2008

A major signaling pathway that regulates platelet shape change and reorganization of the cytoskel... more A major signaling pathway that regulates platelet shape change and reorganization of the cytoskeleton involves the Rho family of GTPases; CDC42 (fillapodia), Rac1 (lamellapodia) and RhoA (focal adhesions). These GTPases are converted from their inactive or GDP-loaded state to the active or GTP-loaded state by a class of enzymes called Guanine Exchange Factors (GEFs). GEFs are a family of multi-domain proteins that contain a GDP-GTP exchange domain (DH-PH) as well as other protein interacting domains that are regulated by the activation of receptors present on the platelet surface. We used an affinity binding technique followed by mass spectroscopy to identify novel Rho family binding GEFs in platelet lysates. Recombinant GST-Rho fusion proteins bound to agarose beads were prepared in the GTP, GDP and nucleotide-free states and incubated with clarified human platelet lysates. Platelet lysate proteins associated with the different GST-Rho preparations were eluted and run on SDS-PAGE. ...

Clinical Biomechanics, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.