Publications by authors named "Alan B Howard"

9 Publications

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Modes of cannabis use: A secondary analysis of an intensive longitudinal natural history study.

Addict Behav 2019 11 24;98:106033. Epub 2019 Jun 24.

Geisel School of Medicine at Dartmouth, Department of Psychiatry, Hanover, NH, USA.

Introduction: There is a paucity of research on modes of cannabis use (e.g., joint vs. blunt), and further, little consensus on how to accurately assess both modes of use and route of administration. This secondary analysis used a longitudinal design with data collected daily to characterize mode of cannabis use.

Methods: 193 adult daily cannabis users who were considering quitting at some point enrolled in the study. No treatment was provided. Each day for 84 days, participants reported on mode of cannabis use (i.e., joints, blunts, pipes/vaporizer and food) using an interactive voice response system. We report on single and poly-use of modes across study days and weeks and examine characteristics associated with different modes of use.

Results: White participants were most likely to use pipes/vaporizer, with use on 57% of study days, while Black participants were most likely to use blunts with use on 53% of days. Thus, joint use was less common in both groups. Poly-use of different modes within the same week was very common (i.e., 56% of weeks among White participants and 60% of weeks in Black participants). Age, gender, race, cannabis dependence, presence of others during cannabis use, and alcohol use were associated with different modes of use.

Conclusions: The major limitation of this study was use of a convenience sample and lack of detailed data on vaporizer use. Joint use is no longer the most common mode of use in either White or Black participants and exclusive use of a single modality is uncommon.
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http://dx.doi.org/10.1016/j.addbeh.2019.106033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6708744PMC
November 2019

INJURY INCIDENCE IN COMPETITIVE CROSS-COUNTRY SKIERS: A PROSPECTIVE COHORT STUDY.

Int J Sports Phys Ther 2019 Apr;14(2):237-252

Professor Emerita, Department of Rehabilitation Sciences, University of Vermont, Burlington, VT, USA.

Background/purpose: Endurance sports, including cross-country skiing, require long hours of repetitive training potentially increasing the chance of injury, yet injury incidence and risk factors for adult cross-country skiers remain relatively unexplored. Data for elite adult north American competitive cross-country skiers is unexplored. A 12 month prospective surveillance study was undertaken to calculate the injury incidence and exposure of cross-country skiers. Injuries by anatomic location and mechanism of injury were calculated. Further, the relationships between new injury and the participant's demographics and physical assessment parameters were examined. The aims of this study were to determine the injury incidence and any risk factors for injury in elite adult north American cross-country skiers.

Methods: Elite cross-country skiers (35 men, 36 women) self-reported demographics, injury history, and injury and training surveillance monthly over 12 months. tests compared the mean number of injuries per individual, per 1,000 training/exposure hours between anatomic regions, type of injuries, and seasons. Spearman's correlation analyses tested the relationship between new injury and Movement Competency Screen (MCS) score, past injury, total training time, and running training time. To determine if new injury could be predicted from any demographic data, intake physical measures, or, monthly injury, training and racing data, a regression model was developed.

Results: Overall, 58% of participants (18 men, 23 women) completed the study, and reported 3.81 injuries per 1,000 training/exposure hours. Over 12-months, lower extremity injury incidence (2.13) was higher than upper extremity (0.46) and trunk injury incidence (0.22) (p < 0.05). Non-traumatic/overuse injury incidence (2.76) was higher than acute injury incidence (1.05) (p < .05). Non-ski-season injury incidence (5.25) was not statistically higher than ski-season injury incidence (2.27) (p = 0.07). New injuries were positively correlated with previous injury (p < 0.05), but not with any other variables (p > 0.05).

Conclusion: In this year-long monthly survey of injuries and training load in elite adult north American cross-country skiers, new injuries were positively correlated with previous injury. Lower extremity, and non-traumatic/overuse injuries had the highest incidence rates. There was no significant correlation between new injuries and physical assessment parameters or training load.

Level Of Evidence: Level 3, Prospective Longitudinal Cohort Study.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6452571PMC
April 2019

Quality of Interhospital Transfer Communication Practices and Association With Adverse Events on an Internal Medicine Hospitalist Service.

J Healthc Qual 2017 May/Jun;39(3):177-185

Communication practices around interhospital transfer have not been rigorously assessed in adult medicine patients. Furthermore, the clinical implications of such practices have not been reported. This case-control study was designed to assess the quality of communication between clinicians during interhospital transfer and to determine if posttransfer adverse events (PTAEs) are associated with suboptimal communication. Cases included patients transferred to a Medicine Hospitalist Service from an outside hospital who subsequently experienced a PTAE, defined as unplanned transfer to an intensive care unit or death within 24 hours of transfer. Control patients also underwent interhospital transfer but did not experience a PTAE. A blinded investigator retrospectively reviewed the recorded pretransfer phone conversations between sending and receiving clinicians for adherence to a set of 13 empiric best practice communication elements. The primary outcome was the mean communication score, on a scale of 0-13. Mean scores between PTAE (8.3; 95% confidence interval [CI], 7.6-8.9) and control groups (7.9; 95% CI, 7.1-8.8) did not differ significantly (p = .50), although suboptimal communication on a subset of these elements was associated with increased PTAEs. Communication around interhospital transfer appears suboptimal compared with an empiric set of standard communication elements. Posttransfer adverse events were not associated with aggregate adherence to these standards.
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http://dx.doi.org/10.1097/01.JHQ.0000462682.32512.adDOI Listing
March 2018

PAC1 receptor antagonism in the bed nucleus of the stria terminalis (BNST) attenuates the endocrine and behavioral consequences of chronic stress.

Psychoneuroendocrinology 2014 Sep 27;47:151-65. Epub 2014 May 27.

Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT 05405, USA. Electronic address:

Chronic or repeated stressor exposure can induce a number of maladaptive behavioral and physiological consequences and among limbic structures, the bed nucleus of the stria terminalis (BNST) has been implicated in the integration and interpretation of stress responses. Previous work has demonstrated that chronic variate stress (CVS) exposure in rodents increases BNST pituitary adenylate cyclase activating polypeptide (PACAP, Adcyap1) and PAC1 receptor (Adcyap1r1) transcript expression, and that acute BNST PACAP injections can stimulate anxiety-like behavior. Here we show that chronic stress increases PACAP expression selectively in the oval nucleus of the dorsolateral BNST in patterns distinct from those for corticotropin releasing hormone (CRH). Among receptor subtypes, BNST PACAP signaling through PAC1 receptors not only heightened anxiety responses as measured by different behavioral parameters but also induced anorexic-like behavior to mimic the consequences of stress. Conversely, chronic inhibition of BNST PACAP signaling by continuous infusion with the PAC1 receptor antagonist PACAP(6-38) during the week of CVS attenuated these stress-induced behavioral responses and changes in weight gain. BNST PACAP signaling stimulated the hypothalamic-pituitary-adrenal (HPA) axis and heightened corticosterone release; further, BNST PACAP(6-38) administration blocked corticosterone release in a sensitized stress model. In aggregate with recent associations of PACAP/PAC1 receptor dysregulation with altered stress responses including post-traumatic stress disorder, these data suggest that BNST PACAP/PAC1 receptor signaling mechanisms may coordinate the behavioral and endocrine consequences of stress.
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http://dx.doi.org/10.1016/j.psyneuen.2014.05.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4342758PMC
September 2014

Analyzing glenohumeral torque-rotation response in vivo.

Clin Biomech (Bristol, Avon) 2010 Oct 6;25(8):759-64. Epub 2010 Jul 6.

McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, University of Vermont, College of Medicine, 438 Stafford Hall, Burlington, VT 05405, USA.

Background: Because the human shoulder has many degrees of freedom that allow redundant means of producing the same net humerothoracic motion, there are many impediments to objective, repeatable assessment of shoulder function in vivo. Devices designed to date have suffered from poor reliability. In this study we introduce a new device and methods to evaluate human shoulder kinematics and evaluate its reproducibility from subject to subject and from day to day.

Methods: This was a controlled laboratory study. Using electromagnetic motion sensors to record the position and orientation of the thorax, scapula, and humerus, we quantified the kinematic response of twenty four normal shoulders in response to known internal-external torque application. A four-parameter logistic function was selected to characterize the strident features of the torque-rotation relationship.

Findings: Our analysis in conjunction with the measurement technique described herein, allowed the passive glenohumeral internal-external range of motion to be differentiated from other motion components and was determined to within 9.6% of full scale over three repeated trials. Range of motion was the most reliable biomechanical outcome, more so than computed indices of glenohumeral flexibility and hysteresis. The exact profile of the torque-rotation response, and therefore the repeatability of the calculated outcomes, was unique from shoulder to shoulder.

Interpretation: The development of the capacity for precise, non-invasive measurement of shoulder biomechanics over time is a requisite step towards optimizing treatment of shoulder injury and disease. Our current methods are superior to previous attempts at trying to non-invasively evaluate the biomechanics of the glenohumeral joint.
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http://dx.doi.org/10.1016/j.clinbiomech.2010.06.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2919603PMC
October 2010

CD133 identifies a human bone marrow stem/progenitor cell sub-population with a repertoire of secreted factors that protect against stroke.

Mol Ther 2009 Nov 18;17(11):1938-47. Epub 2009 Aug 18.

Department of Medicine, Stem Cell Core, University of Vermont, Colchester, Vermont 05446, USA.

The reparative properties of bone marrow stromal cells (BMSCs) have been attributed in part to the paracrine action of secreted factors. We isolated typical human BMSCs by plastic adherence and compared them with BMSC sub-populations isolated by magnetic-activated cell sorting against CD133 (CD133-derived BMSCs, CD133BMSCs) or CD271 [p75 low-affinity nerve growth factor receptor (p75LNGFR), p75BMSCs]. Microarray assays of expressed genes, and enzyme-linked immunosorbent assays (ELISAs) of selected growth factors and cytokines secreted under normoxic and hypoxic conditions demonstrated that the three transit-amplifying progenitor cell populations were distinct from one another. CD133BMSC-conditioned medium (CdM) was superior to p75BMSC CdM in protecting neural progenitor cells against cell death during growth factor/nutrient withdrawal. Intracardiac (arterial) administration of concentrated CD133BMSC CdM provided neuroprotection and significantly reduced cortical infarct volumes in mice following cerebral ischemia. In support of the paracrine hypothesis for BMSC action, intra-arterial infusion of CD133BMSC CdM provided significantly greater protection against stroke compared with the effects of CD133BMSC (cell) administration. CdM from CD133BMSCs also provided superior protection against stroke compared with that conferred by CdM from p75BMSCs or typically isolated BMSCs. CD133 identifies a sub-population of nonhematopoietic stem/progenitor cells from adult human bone marrow, and CD133BMSC CdM may provide neuroprotection for patients with stroke.
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http://dx.doi.org/10.1038/mt.2009.185DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2835040PMC
November 2009

Tamoxifen and aromatase inhibitors differentially affect vascular endothelial growth factor and endostatin levels in women with breast cancer.

Clin Cancer Res 2008 May;14(10):3070-6

Department of Medicine, University of Vermont, Burlington, Vermont, USA.

Purpose: Circulating and cellular proangiogenic and antiangiogenic proteins such as vascular endothelial growth factor (VEGF) and endostatin contribute to the local angiogenic balance. We explored the effects of tamoxifen and aromatase inhibitors on concentrations of VEGF and endostatin in plasma, serum, and platelet releasate (induced by platelet activation).

Experimental Design: VEGF and endostatin concentrations were measured with a quantitative immunoassay before and after 1 to 5 weeks of treatment in 30 women with breast cancer treated with either tamoxifen (n = 14) or aromatase inhibitors (n = 16). Platelet activation was induced by a thrombin receptor agonist.

Results: Tamoxifen therapy resulted in an increase in platelet releasate concentrations of VEGF (P = 0.01) but no change in plasma VEGF. In contrast, aromatase inhibitor therapy did not affect serum, plasma, or platelet releasate VEGF. In univariate analysis, aspirin use attenuated the tamoxifen-associated increase in VEGF in the platelet releasate and decreased serum levels of VEGF (P = 0.03). Aromatase inhibitor therapy resulted in a decrease in serum endostatin concentrations (P = 0.04), whereas plasma concentrations of endostatin tended to be higher during treatment with aromatase inhibitors (P = 0.06). Tamoxifen therapy resulted in no change in serum or plasma endostatin concentrations. Platelet releasate concentrations of endostatin did not change with either treatment. Interindividual variability was noted among both aromatase inhibitor--and tamoxifen-treated patients.

Conclusions: Tamoxifen and aromatase inhibitor therapy affect VEGF and endostatin levels and likely contribute to the angiogenic balance in breast cancer patients. Aspirin decreased the proangiogenic effects of tamoxifen, suggesting that antiplatelet and/or antiangiogenic therapy might improve the effectiveness of tamoxifen in women with breast cancer.
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http://dx.doi.org/10.1158/1078-0432.CCR-07-4640DOI Listing
May 2008

Personal digital assistants are comparable to traditional diaries for dietary self-monitoring during a weight loss program.

J Behav Med 2007 Apr 10;30(2):165-75. Epub 2007 Jan 10.

Department of Nutrition and Food Sciences, University of Vermont, Burlington, VT, Canada.

Dietary self-monitoring is considered the core of behavioral weight control programs. As software for personal digital assistants (PDA) has become more available, this study investigated whether the use of a PDA would improve dietary self-monitoring frequency and subsequent weight loss over the use of traditional paper diaries. One-hundred-seventy-six adults (BMI 25-39.9) participated in a 6-month behavioral weight control program. Treatment subjects (n = 61) were provided with a PalmZire 21 with Calorie King's Diet Diary software installed. Their self-monitoring habits and weight loss were compared with the results from a previous program (n = 115) which followed the same protocol using paper diaries for self-monitoring. No significant differences in weight loss or dietary self-monitoring were found. More frequent self-monitoring correlated with weight loss in both groups (p<.001). People seeking to lose weight should be encouraged to self-monitor and be matched with a mode of self-monitoring that is fitting to their lifestyle and skills.
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http://dx.doi.org/10.1007/s10865-006-9092-1DOI Listing
April 2007

Matrix metalloproteinase activity in thoracic aortic aneurysms associated with bicuspid and tricuspid aortic valves.

J Thorac Cardiovasc Surg 2004 Mar;127(3):686-91

Department of Surgery, Division of Cardiothoracic Surgery, Fletcher Allen Health Care, Fletcher 454, 111 Colchester Avenue, Burlington, VT 05401, USA.

Objective: Matrix metalloproteinases are endopeptidases that function in cell matrix turnover. Abnormal matrix metalloproteinase activity has been implicated in the formation of atherosclerotic abdominal aortic aneurysms. Recent studies suggest that abnormal matrix metalloproteinase activity may also be associated with the formation of atherosclerotic and nonatherosclerotic thoracic aortic aneurysms. Bicuspid aortic valves are associated with an intrinsic aortic pathology that predisposes to formation of proximal thoracic aneurysms while tricuspid aortic valves are not. The objective of this study was to compare the activities of matrix metalloproteinases and levels of their inhibitors in thoracic aneurysms of patients with bicuspid and tricuspid aortic valves.

Methods: Endogenous and total activity of matrix metalloproteinase-2 and matrix metalloproteinase-9 were measured in proximal nonatherosclerotic thoracic aortic aneurysms of 16 patients with bicuspid aortic valves and 12 patients with tricuspid aortic valves. Levels of tissue inhibitor metalloproteinase-1 and -2 were also measured. Results were standardized to total protein (mg).

Results: Total matrix metalloproteinase-2 activity was greater in aneurysms associated with bicuspid valves when compared with those from tricuspid valves (43 +/- 11 ng/mg vs 14 +/- 2 ng/mg, P =.02). Total matrix metalloproteinase-9 activity was also greater in aneurysms associated with bicuspid aortic valves (4.0 +/- 0.9 vs 1.5 +/- 0.3, P =.02). There was no meaningful difference between groups in levels of tissue inhibitor-1 and -2.

Conclusion: The increased activity of matrix metalloproteinases in the walls of aneurysms associated with bicuspid aortic valves may partly explain the predilection to aneurysm formation in these patients.
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http://dx.doi.org/10.1016/j.jtcvs.2003.11.049DOI Listing
March 2004
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