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Zoughaib WS, Hoffman RL, Yates BA, Moorthi RN, Lim K, Coggan AR. Short-term beetroot juice supplementation improves muscle speed and power but does not reduce blood pressure or oxidative stress in 65-79 y old men and women. Nitric Oxide 2023; 138-139:34-41. [PMID: 37244392 PMCID: PMC10527284 DOI: 10.1016/j.niox.2023.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 05/08/2023] [Accepted: 05/24/2023] [Indexed: 05/29/2023]
Abstract
We have previously demonstrated that acute ingestion of inorganic nitrate (NO3-)-rich beetroot juice (BRJ), a source of nitric oxide (NO) via the NO3- → nitrite (NO2-) → NO pathway, can improve muscle speed and power in older individuals. It is not known, however, whether this effect is maintained or perhaps even enhanced with repeated ingestion, or if tolerance develops as with organic nitrates, e.g., nitroglycerin. Using a double-blind, placebo-controlled, crossover design, we therefore studied 16 community-dwelling older (age 71 ± 5 y) individuals after both acute and short-term (i.e., daily for 2 wk) BRJ supplementation. Blood samples were drawn and blood pressure was measured periodically during each ∼3 h experiment, with muscle function determined using isokinetic dynamometry. Acute ingestion of BRJ containing 18.2 ± 6.2 mmol of NO3- increased plasma NO3- and NO2- concentrations 23 ± 11 and 2.7 ± 2.1-fold over placebo, respectively. This was accompanied by 5 ± 11% and 7 ± 13% increases in maximal knee extensor speed (Vmax) and power (Pmax), respectively. After daily supplementation for 2 wk, BRJ ingestion elevated NO3- and NO2- levels 24 ± 12 and 3.3 ± 4.0-fold, respectively, whereas Vmax and Pmax were 7 ± 9% and 9 ± 11% higher than baseline. No changes were observed in blood pressure or in plasma markers of oxidative stress with either acute or short-term NO3- supplementation. We conclude that both acute and short-term dietary NO3- supplementation result in similar improvements in muscle function in older individuals. The magnitudes of these improvements are sufficient to offset the decline resulting from a decade or more of aging and are therefore likely to be clinically significant.
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Affiliation(s)
- William S Zoughaib
- Department of Kinesiology, School of Health & Human Sciences, Indiana University Purdue University, Indianapolis, USA
| | - Richard L Hoffman
- Department of Kinesiology, School of Health & Human Sciences, Indiana University Purdue University, Indianapolis, USA
| | - Brandon A Yates
- Indiana Center for Musculoskeletal Health, School of Medicine, Indiana University School of Medicine, USA
| | - Ranjani N Moorthi
- Division of Nephrology & Hypertension, School of Medicine, Indiana University School of Medicine, USA
| | - Kenneth Lim
- Division of Nephrology & Hypertension, School of Medicine, Indiana University School of Medicine, USA
| | - Andrew R Coggan
- Department of Kinesiology, School of Health & Human Sciences, Indiana University Purdue University, Indianapolis, USA; Indiana Center for Musculoskeletal Health, School of Medicine, Indiana University School of Medicine, USA.
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Zoughaib WS, Hoffman RL, Yates BA, Moorthi RN, Lim K, Coggan AR. The influence of acute dietary nitrate supplementation on skeletal muscle fatigue and recovery in older women. Physiol Rep 2023; 11:e15694. [PMID: 37226336 DOI: 10.14814/phy2.15694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/05/2023] [Accepted: 05/06/2023] [Indexed: 05/26/2023] Open
Abstract
Older individuals fatigue more rapidly during, and recover more slowly from, dynamic exercise. Women are particularly vulnerable to these deleterious effects of aging, which increases their risk of falling. We have shown that dietary nitrate (NO3 - ), a source of nitric oxide (NO) via the NO3 - → nitrite (NO2 - ) → NO pathway, enhances muscle speed and power in older individuals in the non-fatigued state; however, it is unclear if it reduces fatigability and/or improves recoverability in this population. Using a double-blind, placebo-controlled, crossover design, we studied 18 older (age 70 ± 4 years) women who were administered an acute dose of beetroot juice (BRJ) containing either 15.6 ± 3.6 or <0.05 mmol of NO3 - . Blood samples were drawn throughout each ~3 h visit for plasma NO3 - and NO2 - analysis. Peak torque was measured during, and periodically for 10 min after, 50 maximal knee extensions performed at 3.14 rad/s on an isokinetic dynamometer. Ingestion of NO3 - -containing BRJ increased plasma NO3 - and NO2 - concentrations by 21 ± 8 and 4 ± 4 fold, respectively. However, there were no differences in muscle fatigue or recovery. Dietary NO3 - increases plasma NO3 - and NO2 - concentrations but does not reduce fatigability during or enhance recoverability after high intensity exercise in older women.
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Affiliation(s)
- William S Zoughaib
- Department of Kinesiology, School of Health & Human Sciences, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, USA
| | - Richard L Hoffman
- Department of Kinesiology, School of Health & Human Sciences, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, USA
| | - Brandon A Yates
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ranjani N Moorthi
- Division of Nephrology and Hypertension, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Kenneth Lim
- Division of Nephrology and Hypertension, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Andrew R Coggan
- Department of Kinesiology, School of Health & Human Sciences, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, USA
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Zoughaib WS, Hoffman RL, Yates BA, Moorthi RN, Lim K, Coggan AR. The influence of acute dietary nitrate supplementation on skeletal muscle fatigue and recovery in older women. medRxiv 2023:2023.02.15.23285957. [PMID: 36824817 PMCID: PMC9949194 DOI: 10.1101/2023.02.15.23285957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Older individuals fatigue more rapidly during, and recover more slowly from, dynamic exercise. Women are particularly vulnerable to these deleterious effects of aging, which increases their risk of falling. We have shown that dietary nitrate (NO 3 - ), a source of nitric oxide (NO) via the NO 3 - → nitrite (NO 2 - ) → NO pathway, enhances muscle speed and power in older individuals in the non-fatigued state; however, it is unclear if it reduces fatigability and/or improves recoverability in this population. Using a double-blind, placebo-controlled, crossover design, we studied 18 older (age 70 ± 4 y) women who were administered an acute dose of beetroot juice (BRJ) containing either 15.6±3.6 or <0.05 mmol of NO 3 - . Blood samples were drawn throughout each ∼3 h visit for plasma NO 3 - and NO 2 - analysis. Peak torque was measured during, and periodically for 10 min after, 50 maximal knee extensions performed at 3.14 rad/s on an isokinetic dynamometer. Ingestion of NO 3 - -containing BRJ increased plasma NO 3 - and NO 2 - concentrations by 21±8 and 4±4 fold, respectively. However, there were no differences in muscle fatigue or recovery. Dietary NO 3 - increases plasma NO 3 - and NO 2 - concentrations but does not reduce fatigability during or enhance recoverability after high intensity exercise in older women.
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Gallardo EJ, Gray DA, Hoffman RL, Yates BA, Moorthi RN, Coggan AR. Dose-Response Effect of Dietary Nitrate on Muscle Contractility and Blood Pressure in Older Subjects: A Pilot Study. J Gerontol A Biol Sci Med Sci 2021; 76:591-598. [PMID: 33301009 DOI: 10.1093/gerona/glaa311] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Indexed: 02/06/2023] Open
Abstract
We have recently demonstrated that dietary nitrate, a source of nitric oxide (NO) via the nitrate → nitrite → NO enterosalivary pathway, can improve muscle contractility in healthy older men and women. Nitrate ingestion has also been shown to reduce blood pressure in some, but not all, studies of older individuals. However, the optimal dose for eliciting these beneficial effects is unknown. A pilot randomized, double-blind, placebo-controlled crossover study was therefore performed to determine the effects of ingesting 3.3 mL/kg of concentrated beetroot juice containing 0, 200, or 400 µmol/kg of nitrate in 9 healthy older subjects (mean age 70 ± 1 years). Maximal knee extensor power (Pmax) and speed (Vmax) were measured ~2.5 hours after nitrate ingestion using isokinetic dynamometry. Blood pressure was monitored periodically throughout each study. Pmax (in W/kg) was higher (p < .05) after the lower dose (3.9 ± 0.4) compared to the placebo (3.7 ± 0.4) or higher dose (3.7 ± 0.4). Vmax (in rad/s) also tended to be higher (p = .08) after the lower dose (11.9 ± 0.7) compared to the placebo (10.8 ± 0.8) or higher dose (11.2 ± 0.8). Eight out of 9 subjects achieved a higher Pmax and Vmax after the lower versus the higher dose. These dose-related changes in muscle contractility generally paralleled changes in breath NO levels. No significant changes were found in systolic, diastolic, or mean arterial blood pressure. A lower dose of nitrate increases muscle speed and power in healthy older individuals, but these improvements are lost at a higher dose. Blood pressure, on the other hand, is not reduced even with a higher dose.
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Affiliation(s)
- Edgar J Gallardo
- Department of Kinesiology, School of Health and Human Sciences, Indiana University Purdue University Indianapolis
| | - Derrick A Gray
- Department of Kinesiology, School of Health and Human Sciences, Indiana University Purdue University Indianapolis
| | - Richard L Hoffman
- Department of Kinesiology, School of Health and Human Sciences, Indiana University Purdue University Indianapolis
| | - Brandon A Yates
- Department of Kinesiology, School of Health and Human Sciences, Indiana University Purdue University Indianapolis
| | - Ranjani N Moorthi
- Department of Internal Medicine, School of Medicine, Indiana University Purdue University Indianapolis
| | - Andrew R Coggan
- Department of Kinesiology, School of Health and Human Sciences, Indiana University Purdue University Indianapolis
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Coggan AR, Hoffman RL, Gray DA, Moorthi RN, Thomas DP, Leibowitz JL, Thies D, Peterson LR. A Single Dose of Dietary Nitrate Increases Maximal Knee Extensor Angular Velocity and Power in Healthy Older Men and Women. J Gerontol A Biol Sci Med Sci 2021; 75:1154-1160. [PMID: 31231758 DOI: 10.1093/gerona/glz156] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Aging results in reductions in maximal muscular strength, speed, and power, which often lead to functional limitations highly predictive of disability, institutionalization, and mortality in elderly adults. This may be partially due to reduced nitric oxide (NO) bioavailability. We, therefore, hypothesized that dietary nitrate (NO3-), a source of NO via the NO3- → nitrite (NO2-) → NO enterosalivary pathway, could increase muscle contractile function in older subjects. METHODS Twelve healthy older (age 71 ± 5 years) men and women were studied using a randomized, double-blind, placebo-controlled, crossover design. After fasting overnight, subjects were tested 2 hours after ingesting beetroot juice containing or devoid of 13.4 ± 1.6 mmol NO3-. Plasma NO3- and NO2- and breath NO were measured periodically, and muscle function was determined using isokinetic dynamometry. RESULTS N O 3 - ingestion increased (p < .001) plasma NO3-, plasma NO2-, and breath NO by 1,051% ± 433%, 138% ± 149%, and 111% ± 115%, respectively. Maximal velocity of knee extension increased (p < .01) by 10.9% ± 12.1%. Maximal knee extensor power increased (p < .05) by 4.4% ± 7.8%. CONCLUSIONS Acute dietary NO3- intake improves maximal knee extensor angular velocity and power in older individuals. These findings may have important implications for this population, in whom diminished muscle function can lead to functional limitations, dependence, and even premature death.
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Affiliation(s)
- Andrew R Coggan
- Department of Kinesiology, Indiana University-Purdue University Indianapolis.,Department of Cellular and Integrative Physiology, Indiana University-Purdue University Indianapolis
| | - Richard L Hoffman
- Department of Kinesiology, Indiana University-Purdue University Indianapolis
| | - Derrick A Gray
- Department of Kinesiology, Indiana University-Purdue University Indianapolis
| | - Ranjani N Moorthi
- Department of Internal Medicine, Indiana University-Purdue University Indianapolis
| | - Deepak P Thomas
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Joshua L Leibowitz
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri.,Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Dakkota Thies
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Linda R Peterson
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri.,Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
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Dasani SS, Simmons KD, Wirtalla CJ, Hoffman RL, Kelz RR. Understanding the Clinical Implications of Resident Involvement in Uncommon Operations. J Surg Educ 2019; 76:1319-1328. [PMID: 30979651 DOI: 10.1016/j.jsurg.2019.03.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 02/10/2019] [Accepted: 03/17/2019] [Indexed: 06/09/2023]
Abstract
OBJECTIVE The objective of this study was to examine uncommon operations in greater detail given that the outcomes of uncommon operations are largely understudied. This study examines the incidence of postoperative events and the role of the resident following uncommon operations. DESIGN We identified uncommon general surgical operations using the ACS National Surgical Quality Improvement Program Participant Use file (2008-2011). Death or serious morbidity (DSM) within 30 days of the operation was the primary outcome of interest. Failure to rescue (FTR) and prolonged operative time (PRopt) were evaluated as secondary outcome measures. PRopt was defined as ≥90 percentile of operative time for each procedure type. Independent multivariate logistic regression models were generated to examine the impact of these descriptors on the outcomes of interest. SETTING/PARTICIPANTS The dataset utilized was the United States National Surgical Quality Improvement Program Participant Use File which leverages data points from over 700 hospitals that range from primary to quaternary care centers. Resident participation was defined as resident involved (RI) or no resident involved (NRI), and stratified by postgraduate year (PGY): 1-3, 4-5, and 6+. RESULTS Resident participant data was available for 21,453 (84.5%) uncommon operations with NRI in 25.4% (5447). With regard to resident participation, PGY1-3 were found in 12.6% (2699), PGY4-5 in 50.4% (10,817), and PGY6+ in 11.6% (2490). The overall observed DSM rate was 28.6% and the observed FTR rate was 5.8%. Overall, there was no difference in DSM by RI status (NRI: 1528; 28.1% vs RI: 4602; 28.8%; p = 0.324); however, PGY level was associated with DSM (PGY1-3: 774, 28.7%, PGY4-5: 3210, 29.7%, PGY6+: 618, 24.8%; p < 0.001). Any RI was associated with a lower rate of FTR (5.1%) when compared to NRI (8.3%, p < 0.001) with decreasing FTR events by increasing PGY (PGY1-3: 6.4%, PGY4-5: 5.2%, PGY6+: 3.3%; p < 0.001). After adjustment for patient risk factors, any RI remained associated with a lower likelihood of FTR than NRI (odds ratio: 0.65, 95% confidence interval: 0.49-0.87) while only the PGY4-5 and PGY6+ groups were associated with lower likelihood of FTR in comparison to NRI. RI was associated with PRopt in univariate and multivariable analyses. CONCLUSIONS Uncommon operations were associated with substantial DSM. The involvement of PGY4-5 residents was associated with the greatest likelihood of DSM. With increasing PGY of the involved resident, cases with PGY > 5 demonstrated a lower likelihood of risk-adjusted FTR. The explanation for these findings is not clear; however, the involvement of more senior residents in the technical aspects of uncommon operations may lead to improved results.
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Affiliation(s)
- Serena S Dasani
- Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
| | - K D Simmons
- Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
| | - C J Wirtalla
- Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
| | - R L Hoffman
- Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
| | - R R Kelz
- Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
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Williams PS, Hoffman RL, Clark BC. Cortical and spinal mechanisms of task failure of sustained submaximal fatiguing contractions. PLoS One 2014; 9:e93284. [PMID: 24667484 PMCID: PMC3965562 DOI: 10.1371/journal.pone.0093284] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 03/04/2014] [Indexed: 01/19/2023] Open
Abstract
In this and the subsequent companion paper, results are presented that collectively seek to delineate the contribution that supraspinal circuits have in determining the time to task failure (TTF) of sustained submaximal contractions. The purpose of this study was to compare adjustments in supraspinal and spinal excitability taken concurrently throughout the performance of two different fatigue tasks with identical mechanical demands but different TTF (i.e., force-matching and position-matching tasks). On separate visits, ten healthy volunteers performed the force-matching or position-matching task at 15% of maximum strength with the elbow flexors to task failure. Single-pulse transcranial magnetic stimulation (TMS), paired-pulse TMS, paired cortico-cervicomedullary stimulation, and brachial plexus electrical stimulation were delivered in a 6-stimuli sequence at baseline and every 2-3 minutes throughout fatigue-task performance. Contrary to expectations, the force-matching task TTF was 42% shorter (17.5 ± 7.9 min) than the position-matching task (26.9 ± 15.11 min; p<0.01); however, both tasks caused the same amount of muscle fatigue (p = 0.59). There were no task-specific differences for the total amount or rate of change in the neurophysiologic outcome variables over time (p>0.05). Therefore, failure occurred after a similar mean decline in motorneuron excitability developed (p<0.02, ES = 0.35-0.52) coupled with a similar mean increase in measures of corticospinal excitability (p<0.03, ES = 0.30-0.41). Additionally, the amount of intracortical inhibition decreased (p<0.03, ES = 0.32) and the amount of intracortical facilitation (p>0.10) and an index of upstream excitation of the motor cortex remained constant (p>0.40). Together, these results suggest that as fatigue develops prior to task failure, the increase in corticospinal excitability observed in relationship to the decrease in spinal excitability results from a combination of decreasing intracortical inhibition with constant levels of intracortical facilitation and upstream excitability that together eventually fail to provide the input to the motor cortex necessary for descending drive to overcome the spinal cord resistance, thereby contributing to task failure.
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Affiliation(s)
- Petra S. Williams
- Ohio Musculoskeletal & Neurological Institute (OMNI), Ohio University, Athens, Ohio, United States of America
- Department of Physical Therapy and Athletic Training, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Richard L. Hoffman
- Ohio Musculoskeletal & Neurological Institute (OMNI), Ohio University, Athens, Ohio, United States of America
| | - Brian C. Clark
- Ohio Musculoskeletal & Neurological Institute (OMNI), Ohio University, Athens, Ohio, United States of America
- Department of Biomedical Sciences, Ohio University, Athens, Ohio, United States of America
- Department of Geriatric Medicine and Gerontology, Ohio University, Athens, Ohio, United States of America
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Williams PS, Hoffman RL, Clark BC. Preliminary evidence that anodal transcranial direct current stimulation enhances time to task failure of a sustained submaximal contraction. PLoS One 2013; 8:e81418. [PMID: 24349067 PMCID: PMC3857184 DOI: 10.1371/journal.pone.0081418] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 10/11/2013] [Indexed: 12/21/2022] Open
Abstract
The purpose of this study was to determine whether anodal transcranial direct current stimulation (tDCS) delivered while performing a sustained submaximal contraction would increase time to task failure (TTF) compared to sham stimulation. Healthy volunteers (n = 18) performed two fatiguing contractions at 20% of maximum strength with the elbow flexors on separate occasions. During fatigue task performance, either anodal or sham stimulation was delivered to the motor cortex for up to 20 minutes. Transcranial magnetic stimulation (TMS) was used to assess changes in cortical excitability during stimulation. There was no systematic effect of the anodal tDCS stimulation on TTF for the entire subject set (n = 18; p = 0.64). Accordingly, a posteriori subjects were divided into two tDCS-time groups: Full-Time (n = 8), where TTF occurred prior to the termination of tDCS, and Part-Time (n = 10), where TTF extended after tDCS terminated. The TTF for the Full-Time group was 31% longer with anodal tDCS compared to sham (p = 0.04), whereas TTF for the Part-Time group did not differ (p = 0.81). Therefore, the remainder of our analysis addressed the Full-Time group. With anodal tDCS, the amount of muscle fatigue was 6% greater at task failure (p = 0.05) and the amount of time the Full-Time group performed the task at an RPE between 8-10 ("very hard") increased by 38% (p = 0.04) compared to sham. There was no difference in measures of cortical excitability between stimulation conditions (p = 0.90). That the targeted delivery of anodal tDCS during task performance both increased TTF and the amount of muscle fatigue in a subset of subjects suggests that augmenting cortical excitability with tDCS enhanced descending drive to the spinal motorpool to recruit more motor units. The results also suggest that the application of tDCS during performance of fatiguing activity has the potential to bolster the capacity to exercise under conditions required to derive benefits due to overload.
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Affiliation(s)
- Petra S. Williams
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, Ohio, United States of America
- Department of Physical Therapy and Athletic Training, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Richard L. Hoffman
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, Ohio, United States of America
| | - Brian C. Clark
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, Ohio, United States of America
- Department of Biomedical Sciences, Ohio University, Athens, Ohio, United States of America
- Department of Geriatric Medicine and Gerontology, Ohio University, Athens, Ohio, United States of America
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Kaya RD, Hoffman RL, Clark BC. Reliability of a modified motor unit number index (MUNIX) technique. J Electromyogr Kinesiol 2013; 24:18-24. [PMID: 24168818 DOI: 10.1016/j.jelekin.2013.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 09/23/2013] [Accepted: 10/07/2013] [Indexed: 12/14/2022] Open
Abstract
INTRODUCTION The purpose of this study was to examine the relative and absolute between-day reliability of the motor unit number index (MUNIX). METHODS Young, healthy adults (n=19) attended two testing sessions separated by 4-weeks where their maximal pinch-grip strength, MUNIX, and motor unit size index (MUSIX) were assessed in the abductor pollicis brevis muscle. Reliability was assessed by intraclass correlation coefficients (ICC), coefficient of variation (CV) and limits of agreement (LOA). RESULTS No mean differences were observed for MUNIX or MUSIX. The CV for the MUNIX and MUSIX measures were between 13.5% and 17.5%. The ICC for both measures were moderate to moderately-high (0.73-0.76), The LOA for both indicated a homoscedastic relationship. DISCUSSION Our findings indicate moderate to moderately-high reliability for both MUNIX and MUSIX. Future work is needed to ensure both measures are reliable in other muscles and cohorts, and further investigations are required to examine the validity of MUNIX.
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Affiliation(s)
- Ryan D Kaya
- Ohio Musculoskeletal and Neurological Institute (OMNI) at Ohio University, Athens, OH, United States; School of Applied Health Sciences and Wellness at Ohio University, Athens, OH, United States
| | - Richard L Hoffman
- Ohio Musculoskeletal and Neurological Institute (OMNI) at Ohio University, Athens, OH, United States; Department of Biomedical Sciences at Ohio University, Athens, OH, United States
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI) at Ohio University, Athens, OH, United States; Department of Biomedical Sciences at Ohio University, Athens, OH, United States.
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Kaya RD, Nakazawa M, Hoffman RL, Clark BC. Interrelationship between muscle strength, motor units, and aging. Exp Gerontol 2013; 48:920-5. [PMID: 23832080 PMCID: PMC3750065 DOI: 10.1016/j.exger.2013.06.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 06/24/2013] [Accepted: 06/27/2013] [Indexed: 12/14/2022]
Abstract
The interrelationship between muscle strength, motor unit (MU) number, and age is poorly understood, and in this study we sought to determine whether age-related differences in muscle strength are moderated by estimates of functioning MU number and size. Eighteen older adults (OA; 67 ± 1.20 years) and 24 young adults (YA; 22 ± 0.74 years) participated in this study. Maximum voluntary pinch-grip strength of the nondominant hand was determined and estimates of MU number were obtained from the abductor pollicis brevis muscle using the noninvasive motor unit number index (MUNIX) technique. The MUNIX technique was also utilized to derive a motor unit size index (MUSIX). An analysis of covariance (Age Group × MUNIX or MUSIX) was used to test heterogeneity of regression slopes, with body mass and gender serving as covariates. We observed that the slope of pinch-grip strength on the estimated number of MUs between YA and OA differed, indicated by an Age Group × MUNIX interaction (p = 0.04). Specifically, after controlling for the effect of body mass and gender, the slope in OA was significantly positive (0.14 ± 0.06 N/MUs, p = 0.03), whereas no such relationship was found in YA (-0.08 ± 0.09 N/MUs, p = 0.35). A significant Age Group × MUSIX interaction was also observed for strength (p < 0.01). In contrast to MUNIX, the slope in younger adults was significantly positive (0.48 ± 0.11 N/μV, p < 0.01), whereas no such relationship was found in older adults (-0.30 ± 0.22 N/μV, p = 0.18). These findings indicate that there is an interrelationship between muscle strength, MU numbers, and aging, which suggests that a portion of muscle weakness in seniors may be attributable to the loss of functioning motor units.
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Affiliation(s)
- Ryan D. Kaya
- Ohio Musculoskeletal & Neurological Institute (OMNI), Ohio University, Athens, OH USA
- School of Applied Health and Wellness, Ohio University, Athens, OH USA
| | - Masato Nakazawa
- Ohio Musculoskeletal & Neurological Institute (OMNI), Ohio University, Athens, OH USA
- Office of Research and Grants, Ohio University, Athens, OH USA
| | - Richard L. Hoffman
- Ohio Musculoskeletal & Neurological Institute (OMNI), Ohio University, Athens, OH USA
- Department of Biomedical Sciences, Ohio University, Athens, OH USA
| | - Brian C. Clark
- Ohio Musculoskeletal & Neurological Institute (OMNI), Ohio University, Athens, OH USA
- Department of Biomedical Sciences, Ohio University, Athens, OH USA
- Department of Geriatric Medicine and Gerontology at Ohio University, Athens, OH USA
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Abstract
Transcranial magnetic stimulation (TMS) has been in use for more than 20 years, and has grown exponentially in popularity over the past decade. While the use of TMS has expanded to the study of many systems and processes during this time, the original application and perhaps one of the most common uses of TMS involves studying the physiology, plasticity and function of the human neuromuscular system. Single pulse TMS applied to the motor cortex excites pyramidal neurons transsynaptically (Figure 1) and results in a measurable electromyographic response that can be used to study and evaluate the integrity and excitability of the corticospinal tract in humans. Additionally, recent advances in magnetic stimulation now allows for partitioning of cortical versus spinal excitability. For example, paired-pulse TMS can be used to assess intracortical facilitatory and inhibitory properties by combining a conditioning stimulus and a test stimulus at different interstimulus intervals. In this video article we will demonstrate the methodological and technical aspects of these techniques. Specifically, we will demonstrate single-pulse and paired-pulse TMS techniques as applied to the flexor carpi radialis (FCR) muscle as well as the erector spinae (ES) musculature. Our laboratory studies the FCR muscle as it is of interest to our research on the effects of wrist-hand cast immobilization on reduced muscle performance, and we study the ES muscles due to these muscles clinical relevance as it relates to low back pain. With this stated, we should note that TMS has been used to study many muscles of the hand, arm and legs, and should iterate that our demonstrations in the FCR and ES muscle groups are only selected examples of TMS being used to study the human neuromuscular system.
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Affiliation(s)
- David A Goss
- Ohio Musculoskeletal and Neurological Institute and Department of Biomedical Sciences, Ohio University, USA
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Abstract
Two chelodesmid millipeds described by Brölemann (1903) from the interior of Bahia have not been reported for over 100 years despite their large size and bright coloration. Originally described as Leptodesmus gounellei and Leptodesmus carminatus, neither species is referable to Leptodesmus as currently defined nor any other established genus. Both have been studied from the type specimens, and are here designated the type species of two new genera, Plectrogonodesmus for gounellei and Baianassa for carminatus. Diagnostic characters are illustrated for both taxa. Intergeneric relationships are at present not evident, and are not suggested pending better understanding of the chelodesmid fauna of eastern Brazil.
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Clark BC, Goss DA, Walkowski S, Hoffman RL, Ross A, Thomas JS. Neurophysiologic effects of spinal manipulation in patients with chronic low back pain. BMC Musculoskelet Disord 2011; 12:170. [PMID: 21781310 PMCID: PMC3149032 DOI: 10.1186/1471-2474-12-170] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 07/22/2011] [Indexed: 11/22/2022] Open
Abstract
Background While there is growing evidence for the efficacy of SM to treat LBP, little is known on the mechanisms and physiologic effects of these treatments. Accordingly, the purpose of this study was to determine whether SM alters the amplitude of the motor evoked potential (MEP) or the short-latency stretch reflex of the erector spinae muscles, and whether these physiologic responses depend on whether SM causes an audible joint sound. Methods We used transcranial magnetic stimulation to elicit MEPs and electromechanical tapping to elicit short-latency stretch reflexes in 10 patients with chronic LBP and 10 asymptomatic controls. Neurophysiologic outcomes were measured before and after SM. Changes in MEP and stretch reflex amplitude were examined based on patient grouping (LBP vs. controls), and whether SM caused an audible joint sound. Results SM did not alter the erector spinae MEP amplitude in patients with LBP (0.80 ± 0.33 vs. 0.80 ± 0.30 μV) or in asymptomatic controls (0.56 ± 0.09 vs. 0.57 ± 0.06 μV). Similarly, SM did not alter the erector spinae stretch reflex amplitude in patients with LBP (0.66 ± 0.12 vs. 0.66 ± 0.15 μV) or in asymptomatic controls (0.60 ± 0.09 vs. 0.55 ± 0.08 μV). Interestingly, study participants exhibiting an audible response exhibited a 20% decrease in the stretch reflex (p < 0.05). Conclusions These findings suggest that a single SM treatment does not systematically alter corticospinal or stretch reflex excitability of the erector spinae muscles (when assessed ~ 10-minutes following SM); however, they do indicate that the stretch reflex is attenuated when SM causes an audible response. This finding provides insight into the mechanisms of SM, and suggests that SM that produces an audible response may mechanistically act to decrease the sensitivity of the muscle spindles and/or the various segmental sites of the Ia reflex pathway.
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Affiliation(s)
- Brian C Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 236 Irvine Hall, Athens, OH 45701, USA.
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Bender RW, Wilson TE, Hoffman RL, Clark BC. Effect Of Passive-Heat Stress On Muscle Fatigue, Central Activation, And Cortical Excitability. Med Sci Sports Exerc 2011. [DOI: 10.1249/01.mss.0000401885.69567.e7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Clark BC, Goss DA, Walkowski S, Hoffman RL, Ross A, Thomas JS. Neurophysiologic Effects of Spinal Manipulation in Patients with Chronic Low Back Pain. Med Sci Sports Exerc 2011. [DOI: 10.1249/01.mss.0000401044.16167.88] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Immobilization reduces muscle performance, and despite these performance losses being associated with neural impairments little is known regarding adaptations in cortical properties. We utilized transcranial magnetic stimulation to assess changes in flexor carpi radialis (FCR) intracortical facilitation (ICF), and short- and long-interval intracortical inhibition (SICI and LICI) in healthy humans undergoing 3 weeks of immobilization. Measurements were obtained at rest and during contraction (15% intensity). Central activation and the Hoffman reflex (H-reflex) were also assessed. Strength decreased 43.2% +/- 6.1% following immobilization, and central activation also decreased (97.5% +/- 2.4% to 73.2% +/- 8.3%). No changes in ICF, SICI, or LICI were observed at rest; however, LICI was increased during contraction (67.5% +/- 6.9% to 53.1% +/- 6.7% of unconditioned response). The increase in LICI correlated with the loss of strength (r = -0.63). The H-reflex increased following immobilization. These findings suggest that immobilization increases intracortical inhibition during contraction, and this increase is primarily mediated by GABA(B) receptors.
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Affiliation(s)
- Brian C Clark
- Institute for Neuromusculoskeletal Research, Ohio University, Athens, Ohio 45701, USA.
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Kushnick MR, Knutson MJ, Guiler MK, McGlynn ML, Manini TM, Hoffman RL, Clark BC. Fibrinogen, D-dimer and tPA Antigen Concentrations Following Acute and Chronic Blood Flow Restricted Resistance Exercise. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000386148.23980.f2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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McGinley M, Hoffman RL, Russ DW, Thomas JS, Clark BC. Older adults exhibit more intracortical inhibition and less intracortical facilitation than young adults. Exp Gerontol 2010; 45:671-8. [PMID: 20417265 DOI: 10.1016/j.exger.2010.04.005] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2009] [Revised: 03/10/2010] [Accepted: 04/14/2010] [Indexed: 11/30/2022]
Abstract
BACKGROUND Aging results in decreased neuromuscular function, which is likely associated with neurologic alterations. At present little is known regarding age-related changes in intracortical properties. METHODS In this study we used transcranial magnetic stimulation (TMS) to measure intracortical facilitation (ICF), short- and long-interval intracortical inhibition (SICI and LICI), motor evoked potential amplitude, and silent period duration in young and older adults (21.4+/-0.8years and 70.9+/-1.8years). These variables were assessed from the flexor carpi radialis muscle of the non-dominant arm under resting conditions, and during a submaximal contraction (intensity 15% maximum strength). RESULTS Older adults exhibited increased SICI and LICI in comparison to young adults (SICI: 29.0+/-9.2% vs. 46.2+/-4.8% of unconditioned pulse; LICI: 6.5+/-1.7% vs. 15.8+/-3.3% of unconditioned pulse; P=0.04), and less ICF under resting conditions (74.6+/-8.7% vs. 104.9+/-6.9% of unconditioned pulse; P=0.02). These age-related differences disappeared during contraction, although the older adults did exhibit a longer silent period during contraction (112.5+/-6.5 vs. 84.0+/-3.9ms; P<0.01). CONCLUSIONS Collectively, these findings suggest increased GABA mediated intracortical inhibition with age.
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Affiliation(s)
- Marisa McGinley
- Institute for Neuromusculoskeletal Research, Ohio University, United States; Department of Biomedical Sciences, Ohio University, United States
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Clark BC, Manini TM, Hoffman RL, Williams PS, Guiler MK, Knutson MJ, McGlynn ML, Kushnick MR. Relative safety of 4 weeks of blood flow-restricted resistance exercise in young, healthy adults. Scand J Med Sci Sports 2010; 21:653-62. [PMID: 21917016 DOI: 10.1111/j.1600-0838.2010.01100.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This study evaluated the effect of 4 weeks of low-load resistance exercise with blood flow restriction (BFRE) on increasing strength in comparison with high-load resistance exercise (HLE), and assessed changes in blood, vascular and neural function. Healthy adults performed leg extension BFRE or HLE 3 days/week at 30% and 80% of strength, respectively. During BFRE, a cuff on the upper leg was inflated to 30% above systolic blood pressure. Strength, pulse-wave velocity (PWV), ankle-brachial index (ABI), prothrombin time (PT) and nerve conduction (NC) were measured before and after training. Markers of coagulation (fibrinogen and D-dimer), fibrinolysis [tissue plasminogen activator (tPA)] and inflammation [high sensitivity C-reactive protein (hsCRP)] were measured in response to the first and last exercise bouts. Strength increased 8% with BFRE and 13% with HLE (P<0.01). No changes in PWV, ABI, PT or NC were observed following training for either group (P>0.05). tPA antigen increased 30-40% immediately following acute bouts of BFRE and HLE (P=0.01). No changes were observed in fibrinogen, D-dimer or hsCRP (P>0.05). These findings indicate that both protocols increase the strength without altering nerve or vascular function, and that a single bout of both protocols increases fibrinolytic activity without altering selected markers of coagulation or inflammation in healthy individuals.
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Affiliation(s)
- B C Clark
- Department of Biomedical Sciences, Institute for Neuromusculoskeletal Research, Ohio University, Athens, Ohio 45701, USA.
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Umbel JD, Hoffman RL, Dearth DJ, Chleboun GS, Manini TM, Clark BC. Delayed-onset muscle soreness induced by low-load blood flow-restricted exercise. Eur J Appl Physiol 2009; 107:687-95. [PMID: 19727801 DOI: 10.1007/s00421-009-1175-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2009] [Indexed: 01/01/2023]
Abstract
We performed two experiments to describe the magnitude of delayed-onset muscle soreness (DOMS) associated with blood flow restriction (BFR) exercise and to determine the contribution of the concentric (CON) versus eccentric (ECC) actions of BFR exercise on DOMS. In experiment 1, nine subjects performed three sets of unilateral knee extension BFR exercise at 35% of maximal voluntary contraction (MVC) to failure with a thigh cuff inflated 30% above brachial systolic pressure. Subjects repeated the protocol with the contralateral limb without flow restriction. Resting soreness (0-10 scale) and algometry (pain-pressure threshold; PPT) were assessed before and 24, 48 and 96 h post-exercise. Additionally, MVC and vastus lateralis cross-sectional area (CSA) were measured as indices of exercise-induced muscle damage. At 24-h post-exercise, BFR exercise resulted in more soreness than exercise without BFR (2.8 +/- 0.3 vs 1.7 +/- 0.5) and greater reductions in PPT (15.2 +/- 1.7 vs. 20 +/- 2.3 N) and MVC (14.1 +/- 2.5% decrease vs. 1.5 +/- 4.5% decrease) (p <or= 0.05). In experiment 2, 15 different subjects performed three sets of unilateral BFR exercise at 35% MVC with one limb performing only the CON action and the contralateral performing the ECC action. The aforementioned indices of DOMS were assessed before exercise and 24, 48 and 96 h post-exercise. At 24 h post-exercise, CON BFR exercise resulted in more resting soreness than ECC BFR exercise (3.0 +/- 0.5 vs. 1.6 +/- 0.4), and a greater decrease in MVC (9.8 +/- 2.7% decrease vs. 3.4 +/- 2.5% decrease) (p <or= 0.05). These data suggest that knee extension BFR exercise induces mild DOMS and that BFR exercise elicits muscle damage under atypical conditions with low-tension concentric contractions.
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Affiliation(s)
- Jonathan D Umbel
- Institute for Neuromusculoskeletal Research, Ohio University, Athens, OH, USA
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Wesener T, Enghoff H, Hoffman RL, Wägele JW, Sierwald P. Revision of the endemic giant fire millipedes of Madagascar, genus Aphistogoniulus (Diplopoda: Spirobolida: Pachybolidae). ACTA ACUST UNITED AC 2009. [DOI: 10.1163/187525409x462403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Dearth DJ, Umbel J, Hoffman RL, Russ DW, Wilson T, Clark BC. Influence Of Fatigue-induced Muscle Afferent Stimulation On Motor Evoked Potentials. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000355627.55220.c4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Umbel J, Hoffman RL, Dearth D, Chleboun GS, Manini TM, Clark BC. Effect Of Blood Flow Restricted Exercise On Delayed Onset Muscle Soreness. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000354986.37768.47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Clark BC, Hoffman RL, Russ DW. Immobilization-induced increase in fatigue resistance is not explained by changes in the muscle metaboreflex. Muscle Nerve 2009; 38:1466-1473. [PMID: 18932206 DOI: 10.1002/mus.21127] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Immobilization has been reported to enhance fatigability, which is paradoxical in light of the metabolic and molecular alterations that occur in atrophied muscles. We examined whether the immobilization-induced enhancement in fatigability was associated with attenuation in the muscle metaboreflex response. Ten subjects were examined after 3 weeks of hand-forearm immobilization. The time to task failure of a handgrip contraction (20% intensity) was determined along with heart rate (HR) and mean arterial pressure (MAP) at rest, during the task and during a 2-min postexercise muscle ischemia (PEMI) test that continues to stimulate the metaboreflex. Immobilization decreased strength by 25% (P<0.01) and increased the time to task failure by 21% (P=0.03). However, no changes were observed for the HR and MAP responses to the exercise task or during PEMI (P>0.05). These findings indicate that the augmentation of time to task failure with immobilization is not associated with changes in the pressor or metaboreflex responses.
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Affiliation(s)
- Brian C Clark
- Institute for Neuromusculoskeletal Research, Department of Biomedical Sciences, 211 Irvine Hall, Ohio University, Athens, Ohio 45701, USA
| | - Richard L Hoffman
- Institute for Neuromusculoskeletal Research, Department of Biomedical Sciences, 211 Irvine Hall, Ohio University, Athens, Ohio 45701, USA
| | - David W Russ
- School of Physical Therapy, Ohio University, Athens, Ohio, USA
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Hoffman RL. A new, disjunct, diplopod genus from Espirito Santo, Brasil (Polydesmida: Chelodesmidae). Pap Avulsos Zool (São Paulo) 2009. [DOI: 10.1590/s0031-10492009004200001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Clark BC, Manini TM, Hoffman RL, Russ DW. Restoration of Voluntary Muscle Strength After 3 Weeks of Cast Immobilization is Suppressed in Women Compared With Men. Arch Phys Med Rehabil 2009; 90:178-80. [DOI: 10.1016/j.apmr.2008.06.032] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 06/16/2008] [Accepted: 06/30/2008] [Indexed: 11/29/2022]
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Hoffman RL. Chelodesmid studies. XIII. A synopsis of the Brasilian tribe Strongylomorphini. Studies on Neotropical Fauna and Environment 2008. [DOI: 10.1080/01650528109360592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Hoffman RL. The milliped genus Mestosoma in Costa Rica (Polydesmida: Paradoxosomatidae)1. Studies on Neotropical Fauna and Environment 2008. [DOI: 10.1080/01650527709360520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Clark BC, Issac LC, Lane JL, Damron LA, Hoffman RL. Neuromuscular plasticity during and following 3 wk of human forearm cast immobilization. J Appl Physiol (1985) 2008; 105:868-78. [PMID: 18635877 DOI: 10.1152/japplphysiol.90530.2008] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prolonged reductions in muscle activity results in alterations in neuromuscular properties; however, the time course of adaptations is not fully understood, and many of the specific adaptations have not been identified. This study evaluated the temporal evolution of adaptations in neuromuscular properties during and following 3 wk of immobilization. We utilized a combination of techniques involving nerve stimulation and transcranial magnetic stimulation to assess changes in central activation of muscle, along with spinal (H reflex) and corticospinal excitability [i.e., motor-evoked potential (MEP) amplitude, silent period (SP)] and contractile properties in 10 healthy humans undergoing 3 wk of forearm immobilization and 9 control subjects. Immobilization induced deficits in central activation (85 +/- 3 to 67 +/- 7% ) that returned to baseline levels 1 wk after cast removal. The flexor carpii radialis MEP amplitude increased greater than twofold after the first week of immobilization and remained elevated throughout immobilization and 1 wk after cast removal. Additionally, we observed a prolongation of the SP 1 wk after cast removal compared with baseline (78.5 +/- 7.1 to 98.2 +/- 8.7 ms). The contractile properties were also altered, since the rate of evoked force relaxation was slower following immobilization (-14.5 +/- 1.4 to -11.3 +/- 1.0% peak force/ms), and remained depressed 1 wk after cast removal (-10.5 +/- 0.8% peak force/ms). These observations detail the time course of adaptations in corticospinal and contractile properties associated with disuse and illustrate the profound effect of immobilization on the human neuromuscular system as evidenced by the alterations in corticospinal excitability persisting 1 wk following cast removal.
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Affiliation(s)
- Brian C Clark
- Dept. of Biomedical Sciences, Ohio Univ. College of Osteopathic Medicine, Athens, OH 45701, USA.
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Damron LA, Dearth DJ, Hoffman RL, Clark BC. Quantification of the corticospinal silent period evoked via transcranial magnetic stimulation. J Neurosci Methods 2008; 173:121-8. [PMID: 18588914 DOI: 10.1016/j.jneumeth.2008.06.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 05/13/2008] [Accepted: 06/01/2008] [Indexed: 12/12/2022]
Abstract
A magnetic pulse to the cortex during a muscle contraction produces a motor evoked potential (MEP) followed by electrical quiescence before activity resumes that is indicative of corticospinal inhibition and commonly referred to as the corticospinal slient period (SP). The purpose of the present study was to determine the effect of stimulus intensity and quantification method on the between-visit variability of the SP in healthy individuals. On two occasions we recorded the SP from 9 humans at 3 stimulus intensities (10, 20 and 30% above active motor threshold [AMT]) and quantified the SP based on 8 common criteria. We evaluated the effect of stimulus intensity on reliability by using the limits of agreement, and this analysis revealed that the lower stimulus intensities (10 and 20% AMT) exhibited heteroscedasticity, which indicates the amount of random error increases as the silent period increases. The 30% AMT intensity was homoscedastic. We used both visual and mathematical approaches to quantify the SP, and observed that the between-visit coefficient of variation (CV) was less for the visual methods, and that the CV was reduced when the SP onset was earliest in the temporal occurrence of events (i.e. MEP onset to EMG return CV=12%). Inter-rater reliability for the visual analyses were high (r=0.91-0.99). These results suggest that SPs evoked with a stimulus intensity >or=30% AMT and quantified visually by defining the start of the SP at stimulus delivery or the start of the MEP be utilized to decrease the between visit variability.
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Affiliation(s)
- Leatha A Damron
- Department of Physical Therapy, SUNY Upstate Medical University, United States
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Clark BC, Issac LC, Lane JL, Hoffman RL. Temporal Changes in Corticospinal Excitability With 21-Days of Forearm Immobilization. Med Sci Sports Exerc 2008. [DOI: 10.1249/01.mss.0000322886.71292.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Clark BC, Hoffman RL, Damron LA. Quantification of the cortical silent period evoked via transcranial magnetic brain stimulation. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.946.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Brian C Clark
- Neuromuscular Physiology LaboratoryDept Biomedical SciencesOhio University College of Osteopathic MedicineAthensOH
| | - Richard L. Hoffman
- Neuromuscular Physiology LaboratoryDept Biomedical SciencesOhio University College of Osteopathic MedicineAthensOH
| | - Leatha A. Damron
- Neuromuscular Physiology LaboratoryDept Biomedical SciencesOhio University College of Osteopathic MedicineAthensOH
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Hoffman RL, Burkhalter EA. Studies on spirostreptoid millipeds XIV. A new species ofGonoplectusfrom Thailand, with notes on the status and distribution of the genus (Spirostreptida: Harpagophoridae). J NAT HIST 2007. [DOI: 10.1080/00222937800770271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Hoffman RL. Studies on spirostreptoid millipeds. XV. On some new or poorly known harpagophorid genera and species from China and the East Indies. J NAT HIST 2007. [DOI: 10.1080/00222938000770481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Hoffman RL, Hoffman CS. Cloning the Schizosaccharomyces pombe lys2+ gene and construction of new molecular genetic tools. Curr Genet 2006; 49:414-20. [PMID: 16491385 PMCID: PMC4418447 DOI: 10.1007/s00294-006-0065-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2006] [Accepted: 02/01/2006] [Indexed: 10/25/2022]
Abstract
Molecular genetic analyses in Schizosaccharomyces pombe rely on selectable markers that are used in cloning vectors or to mark targeted gene deletions and other integrated constructs. In this study, we used genetic mapping data and genomic sequence information to predict the identity of the S. pombe lys2(+) gene, which is homologous to Saccharomyces cerevisiae LYS4(+). We confirmed this prediction, showing that the cloned SPAC343.16 gene can complement a lys2-97 mutant allele, and constructed the lys2(+)-based cloning vector pRH3. In addition, we deleted the S. pombe his7(+) gene with a lys2(+) -marked polymerase chain reaction (PCR) product and the S. pombe lys2(+) gene with a his7(+)-marked PCR product. Strains carrying these deletions of lys2(+) or his7(+) serve as relatively efficient hosts for the deletion of the ade6(+) gene by lys2(+)-- or his7(+)--marked PCR products when compared with hosts carrying lys2 or his7 point mutations. Therefore, these studies provide plasmids and strains allowing the use of lys2(+) as a selectable marker, along with improved strains for the use of his7(+) to mark gene deletions.
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Hoffman RL. <![CDATA[<B>Diplopoda from Rond�nia, Brazil</B>: <B>II. Three new genera in the family Chelodesmidae (Polydesmida)</B>]]>. Pap Avulsos Zool (S�o Paulo) 2006. [DOI: 10.1590/s0031-10492006000500001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Abstract
Poison frogs of the neotropical family Dendrobatidae contain a wide variety of lipophilic alkaloids, which are accumulated from alkaloid-containing arthropods. A small millipede, Rhinotus purpureus (Siphonotidae), occurs microsympatrically with the dendrobatid frog Dendrobates pumilio on Isla Bastimentos, Bocas del Toro Province, Panamá. Methanol extracts of this millipede contain the spiropyrrolizidine O-methyloxime 236, an alkaloid previously known only from skin extracts of poison frogs, including populations of D. pumilio. Thus, R. purpureus represents a likely dietary source of such alkaloids in dendrobatid frogs.
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Affiliation(s)
- R A Saporito
- Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
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McCall RB, Huff R, Chio CL, TenBrink R, Bergh CL, Ennis MD, Ghazal NB, Hoffman RL, Meisheri K, Higdon NR, Hall E. Preclinical studies characterizing the anti-migraine and cardiovascular effects of the selective 5-HT1D receptor agonist PNU-142633. Cephalalgia 2002; 22:799-806. [PMID: 12485205 DOI: 10.1046/j.1468-2982.2002.00459.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The present study describes the preclinical pharmacology of a highly selective 5-HT1D receptor agonist PNU-142633. PNU-142633 binds with a Ki of 6 nm at the human 5-HT1D receptor and a Ki of> 18 000 nm at the human 5-HT1B receptor. The intrinsic activity of PNU-142633 at the human 5-HT1D receptor was determined to be 70% that of 5-HT in a cytosensor cell-based assay compared with 84% for that of sumatriptan. PNU-142633 was equally effective as sumatriptan and a half-log more potent than sumatriptan in preventing plasma protein extravasation induced by electrical stimulation of the trigeminal ganglion. Like sumatriptan, PNU-142633 reduced the increase in cat nucleus trigeminal caudalis blood flow elicited by electrical stimulation of the trigeminal ganglion compared with the vehicle control. The direct vasoconstrictor potential of PNU-142633 was evaluated in vascular beds. Sumatriptan increased vascular resistance in carotid, meningeal and coronary arteries while PNU-142633 failed to alter resistance in these vascular beds. These data are discussed in relation to the clinical findings of PNU-142633 in a phase II acute migraine study.
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Affiliation(s)
- R B McCall
- Department of Neurobiology and Structural, Analytical and Medicinal Chemistry, Pharmacia Corporation, Kalamazoo, MI 49001, USA.
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Hoffman RL. A synopsis of the platyrhacid millipeds of Borneo (Diplopoda: Polydesmida: Platyrhacidae). REV SUISSE ZOOL 2001. [DOI: 10.5962/bhl.part.79637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Haak-Frendscho M, Darvas Z, Hegyesi H, Kárpáti S, Hoffman RL, László V, Bencsáth M, Szalai C, Fürész J, Timár J, Bata-Csörgõ Z, Szabad G, Pivarcsi A, Pállinger E, Kemény L, Horváth A, Dobozy A, Falus A. Histidine decarboxylase expression in human melanoma. J Invest Dermatol 2000; 115:345-52. [PMID: 10951267 DOI: 10.1046/j.1523-1747.2000.00054.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Histamine has been implicated as one of the mediators involved in regulation of proliferation in both normal and neoplastic tissues. Histidine decarboxylase, the only enzyme that catalyzes the formation of histamine from L-histidine, is an essential regulator of histamine levels. In this study, we investigated the gene and protein expression of histidine decarboxylase in melanoma. Reverse transcriptase polymerase chain reaction and in situ hybridization studies of WM-35, WM-983/B, HT-168, and M1 human melanoma cell lines both resulted in positive signals for histidine decarboxylase messenger RNA. A polyclonal chicken antibody was developed against human histidine decarboxylase and protein expression was confirmed by western blot analysis of the cell lysates, revealing a predominant immunoreactive band at approximately 54 kDa corresponding to monomeric histidine decarboxylase. Protein expression of histidine decarboxylase was also shown by flow cytometric analysis and strong punctate cytoplasmic staining of melanoma cell lines. Moreover, both primary and metastatic human melanoma tissues were brightly stained for histidine decarboxylase. When compared with the very weak or no reactions on cultivated human melanocytes both western blot and immunohistochemical studies showed much stronger histidine decarboxylase expression in melanoma cells. These findings suggest that expression of histidine decarboxylase is elevated in human melanoma.
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Affiliation(s)
- M Haak-Frendscho
- Immunology Department, Promega Corporation, Madison, Wisconsin, USA
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Okragly AJ, Niles AL, Saban R, Schmidt D, Hoffman RL, Warner TF, Moon TD, Uehling DT, Haak-Frendscho M. Elevated tryptase, nerve growth factor, neurotrophin-3 and glial cell line-derived neurotrophic factor levels in the urine of interstitial cystitis and bladder cancer patients. J Urol 1999; 161:438-41; discussion 441-2. [PMID: 9915421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
PURPOSE The 2 prominent features of interstitial cystitis are pain and increased numbers of mast cells in the bladder. In this pilot study we determined the concentration of soluble mediators associated with activation of sensory neurons and/or mast cells that were present in the urine. MATERIALS AND METHODS The study groups included 4 interstitial cystitis patients, 7 kidney donors with no history of bladder disease as negative controls, 6 bladder cancer patients and 7 patients with urinary tract infection as reference controls. Urine samples were assayed for different soluble mediators using immunoassays for tryptase (a marker for mast cell activation), neurotrophic factors (markers of neuronal plasticity) and chemokines (markers of inflammatory cell activity). Results were normalized based on creatinine concentration. RESULTS There was a marked increase in the average amounts of tryptase and 3 neurotrophic factors in patient urine. Interestingly, the mediator profile in the urine of bladder cancer patients was indistinguishable from that of interstitial cystitis patients with respect to these same 4 proteins. There was no difference between normal control and urinary tract infection urine samples. CONCLUSIONS These findings may account for several clinical and pathological features found in interstitial cystitis and bladder cancer. Although preliminary due to the limited numbers of patients, they also suggest that increased levels of neurotrophin-3, nerve growth factor, glial cell line-derived neurotrophic factor and tryptase in the urine could serve as a basis for adjunct diagnosis, monitoring and treatment of interstitial cystitis.
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Affiliation(s)
- A J Okragly
- Promega Corporation, University of Wisconsin, Madison, USA
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Colodny L, Hoffman RL. Inositol--clinical applications for exogenous use. Altern Med Rev 1998; 3:432-47. [PMID: 9855568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Recent advances in nutritional and biochemical research have documented inositol as an important dietary and cellular constituent. The processes involved in inositol metabolism and its derivatives in the tissues of mammals have been characterized in vivo as well as at the enzymatic level. Biochemical functions defined for phosphatidylinositol in biological membranes include the regulation of cellular responses to external stimuli and/or nerve transmission as well as the mediation of enzyme activity through interactions with various specific proteins. Altered production of inositol has been documented in patients with diabetes mellitus, chronic renal failure, galactosemia, and multiple sclerosis. Inositol has been reported to be effective in treating central nervous system disorders such as depression, Alzheimer's disease, panic disorder, and obsessive-compulsive disorder. It has documented benefit for use in pediatric respiratory depression syndrome. In addition, recent studies have evaluated its usefulness as an analgesic. Inositol has been studied extensively as potential treatment to alleviate some negative effects associated with lithium therapy. The use of inositol in pregnant women remains controversial. Although its benefit in preventing neural tube defects in embryonic mice is documented, the risk of inducing uterine contractions limits its usefulness in pregnancy.
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Affiliation(s)
- L Colodny
- Pharmacy Services at Broward General Medical Center: 1600 S. Andrews Ave., Ft. Lauderdale, FL 33316, USA
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Ennis MD, Ghazal NB, Hoffman RL, Smith MW, Schlachter SK, Lawson CF, Im WB, Pregenzer JF, Svensson KA, Lewis RA, Hall ED, Sutter DM, Harris LT, McCall RB. Isochroman-6-carboxamides as highly selective 5-HT1D agonists: potential new treatment for migraine without cardiovascular side effects. J Med Chem 1998; 41:2180-3. [PMID: 9632349 DOI: 10.1021/jm980137o] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- M D Ennis
- Pharmacia & Upjohn, Inc., Kalamazoo, Michigan 49001, USA
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Abstract
Schwann cells are excluded from the CNS during development by the glial limiting membrane, an area of astrocytic specialisation present at the nerve root transitional zone, and at blood vessels in the neuropil. This barrier, however, can be disrupted and, with the highly migratory nature of Schwann cells, can result in their invasion and myelination of the CNS in many pathological situations. In this paper we demonstrate that this occurs in a number of myelin mutants, including the myelin deficient (md) and taiep rats and the canine shaking (sh) pup. While it is still relatively uncommon in the rodent mutants, the sh pup shows extensive Schwann cell invasion along the neuraxis. This invasion involves the spinal cord, brain stem, and cerebellum and increases in amount and distribution with age. In situ hybridisation studies using a Pzero riboprobe suggest that the likely origin of these cells in the sh pup is the nerve roots, primarily the dorsal roots. Paradoxically, Schwann cell myelination of the CNS increases with time in the sh pup despite a marked, progressive gliosis involving the glia limitans and neuropil. Thus the mechanism by which these cells migrate into the CNS through the gliosed nerve root transitional zone or from vasa nervorum remains unknown. Extensive Schwann cell CNS myelination may have therapeutic significance in human myelin disease.
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Affiliation(s)
- I D Duncan
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706, USA.
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Hoffman RL. Studies on Spirostreptoid Millipeds. XIX. Identity of Some Species Described by F. KARSCH in 1881. ZOOSYST EVOL 1996. [DOI: 10.1002/mmnz.4830720216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Mundell LD, Smith BP, Hoffman RL. Maxillary sinus cysts in two cattle. J Am Vet Med Assoc 1996; 209:127-9. [PMID: 8926195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Two adult Holstein cattle were found to have unilateral maxillary sinus cysts. One had dyspnea and partial airway obstruction; the other had a swelling over the sinus. Both had a nonfetid, mucoid nasal discharge. Deviation of the nasal septum away from the cyst, soft-tissue opacity involving the left maxillary sinus, and a gas-capped fluid line on lateral projection were identified radiographically. The cyst fluid did not have an odor, was relatively acellular, and was of a mucoid (animal 1) or gelatinous (animal 2) nature. In 1 animal, the cyst wall and fluid were removed through a dorsolateral bone flap. The owner reported that the animal improved rapidly and remained clinically normal 27 months after surgery. In the second animal, the cyst was drained and the cyst lining was curetted through a trephine hole in the sinus. The animal improved, but was euthanatized 4 days after surgery because of concurrent problems (displaced abomasum, poor milk production) and financial constraints of the owner. The cyst walls were composed of granulation tissue and were line with stratified squamous epithelium.
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Affiliation(s)
- L D Mundell
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616, USA
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