Amanda Thimmesch - Academia.edu (original) (raw)

Papers by Amanda Thimmesch

The FASEB Journal

Hemorrhagic shock (HS) and fluid resuscitation (FR) generate reactive oxygen species (ROS) which ... more Hemorrhagic shock (HS) and fluid resuscitation (FR) generate reactive oxygen species (ROS) which is a major factor in post‐hemorrhage inflammation and tissue injury. The hypoxia created by HS/reperfusion injury (RI) alters the microvascular blood flow and microvascular oxygen. The objective of the study was to determine if ubiquinol (reduced form of coenzyme Q10) reduces leukocyte‐endothelium interaction following HS/FR. Intravital microscopy was used to measure leukocyte‐endothelium interactions in the rat mesentery following 1‐hour HS and 2‐hour post FR with or without ubiquinol. HS was induced by removing ~40% of the rats’ blood volume resulting in a mean arterial blood pressure (MABP) being ~44 mmHg for 1‐hour. Immediately afterwards ubiquinol (1 mg/100 g body weight) was infused intra‐arterially. RI was produced by replacing the shed blood and Lactate Ringer’s. Below are the findings (n=6, *p < 0.05): Group Leukocyte Adherence Mast Cell Degranulation Reactive Oxygen Species ...

BMC Health Services Research, Mar 6, 2023

Background The 21 st Century Cures Act Interoperability and Information Blocking Rule was created... more Background The 21 st Century Cures Act Interoperability and Information Blocking Rule was created to increase patient access to health information. This federally mandated policy has been met with praise and concern. However, little is known about patient and clinician opinions of this policy within cancer care. Methods We conducted a convergent parallel mixed methods study to understand patient and clinician reactions to the Information Blocking Rule in cancer care and what they would like policy makers to consider. Twenty-nine patients and 29 clinicians completed interviews and surveys. Inductive thematic analysis was used to analyze the interviews. Interview and survey data were analyzed separately, then linked to generate a full interpretation of the results. Results Overall, patients felt more positive about the policy than clinicians. Patients wanted policy makers to understand that patients are unique, and they want to individualize their preferences for receiving health information with their clinicians. Clinicians highlighted the uniqueness of cancer care, due to the highly sensitive information that is shared. Both patients and clinicians were concerned about the impact on clinician workload and stress. Both expressed an urgent need for tailoring implementation of the policy to avoid unintended harm and distress for patients. Conclusions Our findings provide suggestions for optimizing the implementation of this policy in cancer care. Dissemination strategies to better inform the public about the policy and improve clinician understanding and support are recommended. Patients who have serious illness or diagnoses such as cancer and their clinicians should be included when developing and enacting policies that could have a significant impact on their well-being. Patients with cancer and their cancer care teams want the ability to tailor information release based on individual preferences and goals. Understanding how to tailor implementation of the Information Blocking Rule is essential for retaining its benefits and minimizing unintended harm for patients with cancer.

Research and reviews: journal of nursing and health sciences, Jun 27, 2016

Nursing ... critical care, Sep 1, 2013

The authors have disclosed that they have no fi nancial relationships related to this article.

Journal of Pre-Clinical and Clinical Research, Jun 30, 2010

During resuscitation of hemorrhagic shock (HS), clinicians employ high fractions of inspired oxyg... more During resuscitation of hemorrhagic shock (HS), clinicians employ high fractions of inspired oxygen (FIO 2) to restore maximal oxygen (O 2) saturations. Studies indicate that increased FIO 2 can be detrimental to cellular function. Our purpose was to determine the FIO 2 with and without dopamine (DA) that minimizes hydrogen peroxide (H 2 O 2) production and apoptosis in lung and diaphragm following HS. Sprague-Dawley rats were randomized to FIO 2 groups: 0.21, 0.40, 0.60 and 1.0. Controlled HS was elicited by reducing mean arterial pressure to approx. 40 mm Hg. The rats were treated with various FIO 2 s, with and without DA infusion (10 mcg/kg/min). Hydrogen peroxide was measured using dihydrofl uorescein diacetate. Apoptosis was determined based on nuclear diff erential dye uptake. Compared to 0.21, lung and diaphragm H 2 O 2 and apoptosis were signifi cantly reduced in the 0.40 and 0.60 groups. At an FIO 2 of 1.0, H 2 O 2 and apoptosis were greater than at 0.21. With the exception of an FIO 2 of 0.40, infusing DA with various FIO 2 s resulted in H 2 O 2 and apoptosis being signifi cantly decreased. These results indicate that lung and diaphragm H 2 O 2 and apoptosis are aff ected by inspired O 2 and DA. Results indicate using an FIO 2 of 0.40, with or without DA, is most benefi cial in attenuating tissue damage following HS.

Copyright © 2011 William J. Mach et al. This is an open access article distributed under the Crea... more Copyright © 2011 William J. Mach et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Oxygen (O2) is life essential but as a drug has a maximum positive biological benefit and accompanying toxicity effects. Oxygen is therapeutic for treatment of hypoxemia and hypoxia associated with many pathological processes. Pathophysiological processes are associated with increased levels of hyperoxia-induced reactive O2 species (ROS) which may readily react with surrounding biological tissues, damaging lipids, proteins, and nucleic acids. Protective antioxidant defenses can become overwhelmed with ROS leading to oxidative stress. Activated alveolar capillary endothelium is characterized by increased adhesiveness causing accumulation of cell populations such as neutrophils, which are a source of ROS. Increased levels of ROS cause...

eff ects of increased inspired oxygen with and without dopamine on lung and diaphragm hydrogen pe... more eff ects of increased inspired oxygen with and without dopamine on lung and diaphragm hydrogen peroxide and apoptosis following hemorrhagic shock

Research and reviews: journal of nursing and health sciences, 2016

There is currently no effective clinical treatment for diastolic heart failure also termed heart ... more There is currently no effective clinical treatment for diastolic heart failure also termed heart failure with preserved ejection fraction (HFpEF) which is associated with reduced myocardial adenosine triphosphate. Ubiquinol in the electron chain is required for adenosine triphosphate synthesis. Thus, the purpose of this pilot study was to examine in a rat model the effects of ubiquinol (reduced form of Coenzyme Q10) in the development of HFpEF. Six Dahl salt-sensitive rats were randomly assigned to either control or experimental groups. Starting at the age of 7 weeks, all rats were fed 8% NaCl diet and water for 12 weeks. The rats in the experimental group were fed ubiquinol (2 mg/100 g) in the water. Blood pressures, heart rate, and echocardiographic data were obtained at baseline and at the end of experiment. Rats in the ubiquinol group had lower increases in blood pressures and left ventricular wall thickness. Heart rate variability was not significantly different although there ...

Critical Care Medicine, 2012

Advances in bioscience and clinical medicine, 2018

Mitochondria are important organelles referred to as cellular powerhouses for their unique proper... more Mitochondria are important organelles referred to as cellular powerhouses for their unique properties of cellular energy production. With many pathologic conditions and aging, mitochondrial function declines, and there is a reduction in the production of adenosine triphosphate. The energy carrying molecule generated by cellular respiration and by pentose phosphate pathway, an alternative pathway of glucose metabolism. D-ribose is a naturally occurring monosaccharide found in the cells and particularly in the mitochondria is essential in energy production. Without sufficient energy, cells cannot maintain integrity and function. Supplemental D-ribose has been shown to improve cellular processes when there is mitochondrial dysfunction. When individuals take supplemental D-ribose, it can bypass part of the pentose pathway to produce D-ribose-5-phosphate for the production of energy. In this article, we review how energy is produced by cellular respiration, the pentose pathway, and the u...

$Research paper thumbnail of Study protocol, randomized controlled trial: reducing symptom burden in patients with heart failure with preserved ejection fraction using ubiquinol and/or D-ribose$

BMC cardiovascular disorders, Apr 2, 2018

Heart failure (HF), the leading cause of morbidity and mortality in the US, affects 6.6 million a... more Heart failure (HF), the leading cause of morbidity and mortality in the US, affects 6.6 million adults with an estimated additional 3 million people by 2030. More than 50% of HF patients have heart failure with preserved left ventricular ejection fraction (HFpEF). These patients have impaired cardiac muscle relaxation and diastolic filling, which investigators have associated with cellular energetic impairment. Patients with HFpEF experience symptoms of: (1) fatigue; (2) shortness of breath; and (3) swelling (edema) of the lower extremities. However, current HF guidelines offer no effective treatment to address these underlying pathophysiologic mechanisms. Thus, we propose a biobehavioral symptom science study using ubiquinol and D-ribose (therapeutic interventions) to target mitochondrial bioenergetics to reduce the complex symptoms experienced by patients with HFpEF. Using a randomized, double-blind, placebo-controlled design, the overall objective is to determine if administering...

Journal of neuroscience research, Jan 30, 2018

Following traumatic brain injury (TBI), there is significant secondary damage to cerebral tissue ... more Following traumatic brain injury (TBI), there is significant secondary damage to cerebral tissue from increased free radicals and impaired mitochondrial function. This imbalance between reactive oxygen species (ROS) production and the effectiveness of cellular antioxidant defenses is termed oxidative stress. Often there are insufficient antioxidants to scavenge ROS, leading to alterations in cerebral structure and function. Attenuating oxidative stress following a TBI by administering an antioxidant may decrease secondary brain injury, and currently many drugs and supplements are being investigated. We explored an over-the-counter supplement called ubiquinol (reduced form of coenzyme Q10), a potent antioxidant naturally produced in brain mitochondria. We administered intra-arterial ubiquinol to rats to determine if it would reduce mitochondrial damage, apoptosis, and severity of a contusive TBI. Adult male F344 rats were randomly assigned to one of three groups: (1) Saline-TBI, (2) ...

Journal of advanced nursing, 2017

The aim of this study was to discuss secondary traumatic brain injury, the mitochondria and the u... more The aim of this study was to discuss secondary traumatic brain injury, the mitochondria and the use of antioxidants as a treatment. One of the leading causes of death globally is traumatic brain injury, affecting individuals in all demographics. Traumatic brain injury is produced by an external blunt force or penetration resulting in alterations in brain function or pathology. Often, with a traumatic brain injury, secondary injury causes additional damage to the brain tissue that can have further impact on recovery and the quality of life. Secondary injury occurs when metabolic and physiologic processes alter after initial injury and includes increased release of toxic free radicals that cause damage to adjacent tissues and can eventually lead to neuronal necrosis. Although antioxidants in the tissues can reduce free radical damage, the magnitude of increased free radicals overwhelms the body's reduced defence mechanisms. Supplementing the body's natural supply of antioxidan...

The Open Cardiovascular Medicine Journal, 2016

Heart failure with preserved ejection fraction (HFpEF) is a significant cardiovascular condition ... more Heart failure with preserved ejection fraction (HFpEF) is a significant cardiovascular condition for more than 50% of patients with heart failure. Currently, there is no effective treatment to decrease morbidity and mortality rates associated with HFpEF because of its pathophysiological heterogeneity. Recent evidence shows that deficiency in myocardial bioenergetics is one of the key pathophysiological factors contributing to diastolic dysfunction in HFpEF. Another known mechanism for HFpEF is an overproduction of free radicals, specifically reactive oxygen species. To reduce free radical formation, antioxidants are often used. This article is a summative review of the recent relevant literature that addresses cardiac bioenergetics, deficiency in myocardial bioenergetics, and increased reactive oxygen species associated with HFpEF and the promising potential use of antioxidants in managing this condition.

Worldviews on Evidence-Based Nursing, 2016

ABSTRACTBackgroundTraumatic brain injury (TBI) is an acquired brain injury that occurs when there... more ABSTRACTBackgroundTraumatic brain injury (TBI) is an acquired brain injury that occurs when there is sudden trauma that leads to brain damage. This acute complex event can happen when the head is violently or suddenly struck or an object pierces the skull or brain. The current principal treatment of TBI includes various pharmaceutical agents, hyperbaric oxygen, and hypothermia. There is evidence that secondary injury from a TBI is specifically related to oxidative stress. However, the clinical management of TBI often does not include antioxidants to reduce oxidative stress and prevent secondary injury.AimsThe purpose of this article is to examine current literature regarding the use of antioxidant therapies in treating TBI. This review evaluates the evidence of antioxidant therapy as an adjunctive treatment used to reduce the underlying mechanisms involved in secondary TBI injury.MethodsA systematic review of the literature published between January 2005 and September 2015 was condu...

Journal of Infusion Nursing, 2016

There is still much debate over the optimal fluid to use for resuscitation. Different studies hav... more There is still much debate over the optimal fluid to use for resuscitation. Different studies have indicated either crystalloid or colloid is the ideal intravenous solution to administer, based on mortality or various physiological parameters. Older studies found differences between crystalloids and colloids. However, with the evolving science of fluid administration, more recent studies have shown no differences in patient outcomes. This review article will provide an overview of these substances and discuss the advantages, disadvantages, and implications for giving crystalloids and colloids in clinical practice.

Open Journal of Molecular and Integrative Physiology, 2013

Hemorrhagic shock causes a reduction in oxygen supply to tissues leading to increased reactive ox... more Hemorrhagic shock causes a reduction in oxygen supply to tissues leading to increased reactive oxygen species resulting in lung injury. Often mechanical ventilation is required as supportive treatment; however, ventilation can also induce lung injury and apoptosis. The purpose of this study was to examine the effects of three modes of controlled mechanical ventilation: volume control, pressure control, and pressure regulated volume control on lung injury as measured by hydrogen peroxide and apoptosis during hemorrhagic shock. Male Sprague-Dawley rats were randomized to the three controlled mechanical ventilation groups. Hemorrhagic shock was elicited by removing approximately 40% of the blood volume over 30 minutes. The rats were treated with one of three modes of mechanical ventilation with 40% oxygen for 60 minutes. The lungs were removed and measured for hydrogen peroxide and apoptosis based on nuclear differential dye uptake. There were no significant differences in hemodynamics, arterial blood values, peak inspiratory pressures, tidal volume, respiratory rates, and intrathoracic pressures across three groups. However, lung hydrogen peroxide production and apoptosis were significantly increased in volume control and pressure control, compared to pressure-regulated volume control. In this study, early signs of ventilator induced lung injury were not detected using commonly employed clinical measurements. However, when examining lung cellular injury (hydrogen peroxide and apoptosis), we were able to measure significant lung damage in volume control and pressure control, but not pressure-regulated volume control. Thus, our results suggest that pressure-regulated volume control is the preferable mode of mechanical ventilation during hemorrhagic shock.

The American Journal of the Medical Sciences, 2015

Nursing Research and Practice, 2011

Oxygen (O2) is life essential but as a drug has a maximum positive biological benefit and accompa... more Oxygen (O2) is life essential but as a drug has a maximum positive biological benefit and accompanying toxicity effects. Oxygen is therapeutic for treatment of hypoxemia and hypoxia associated with many pathological processes. Pathophysiological processes are associated with increased levels of hyperoxia-induced reactive O2species (ROS) which may readily react with surrounding biological tissues, damaging lipids, proteins, and nucleic acids. Protective antioxidant defenses can become overwhelmed with ROS leading to oxidative stress. Activated alveolar capillary endothelium is characterized by increased adhesiveness causing accumulation of cell populations such as neutrophils, which are a source of ROS. Increased levels of ROS cause hyperpermeability, coagulopathy, and collagen deposition as well as other irreversible changes occurring within the alveolar space. In hyperoxia, multiple signaling pathways determine the pulmonary cellular response: apoptosis, necrosis, or repair. Unders...