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Janet D Pierce

Publications and source records attributed to Janet D Pierce.

13 recordsLinked to original sources
PubMed2006

Effect of dopamine on rat diaphragm apoptosis and muscle performance.

The purpose of this study was to determine whether dopamine (DA) decreases diaphragm apoptosis and attenuates the decline in diaphragmatic contractile performance associated with repetitive isometric contraction using an in vitro diaphragm preparation. Strenuous diaphragm contractions produce free radicals and muscle apoptosis. Dopamine is a free radical scavenger and, at higher concentrations, increases muscle contractility by simulating beta2-adrenoreceptors. A total of 47 male Sprague-Dawley rats weighing 330-450 g were used in a prospective, randomized, controlled in vitro study. Following animal anaesthetization, diaphragms were excised, and muscle strips prepared and placed in a temperature-controlled isolated tissue bath containing Krebs-Ringer solution (KR) or KR plus 100 microm DA. The solutions were equilibrated with oxygen (O2) at 10, 21 or 95% and 5% carbon dioxide, with the balance being nitrogen. Diaphragm isometric twitch and subtetanic contractions were measured intermittently over 65 min. The diaphragms were then removed and, using a nuclear differential dye uptake method, the percentages of normal, apoptotic and necrotic nuclei were determined using fluorescent microscopy. There were significantly fewer apoptotic nuclei in the DA group diaphragms than in the KR-only group diaphragms in 10 and 21% O2 following either twitch or subtetanic contractions. Dopamine at 100 microm produced only modest increases in muscle performance in both 10 and 21% O2. The attenuation of apoptosis by DA was markedly greater than the effect of DA on muscle performance. Dopamine decreased diaphragmatic apoptosis, perhaps by preventing the activation of intricate apoptotic pathways, stimulating antiapoptotic mechanisms and/or scavenging free radicals.

Animals↗
PubMed2005

A review of free radicals and antioxidants for critical care nurses.

In the critical care setting, nurses frequently care for patients with acute and chronic diseases that affect multiple body systems. Many of these medical conditions have been associated with an imbalance between oxidizing chemicals called free radicals and antioxidants. Free radical damage is now assumed to be a contributing factor in all major diseases. In order to provide the most current and comprehensive care, critical care nurses need to be well informed about how free radicals cause damage and the antioxidant compounds that neutralize their destructive effects. This article provides an overview of oxygen free radicals and antioxidants and how they impact different clinical illnesses familiar to critical care nurses.

Antioxidants↗
PubMed2005

Comparison of a visual to a computer-assisted technique for detecting apoptosis.

In many studies, fluorescent dyes (ethidium bromide [EB] and acridine orange [AO]) are used to stain DNA to determine if nuclei are apoptotic. However, there are numerous visual methods for counting these stained DNA that may lead to inaccuracies Measuring apoptosis by the visual counting method may be imprecise because of the variability of individuals' perception of color. Therefore, the authors compared a visual method of counting chromatin for apoptosis with a method relying on a computer program. They began counting chromatin using the visual method, in which individuals identify the stained DNA using their own visual perception. For comparison, they used a software-based counting method (analySIS software) to determine the color (hue) of the stained DNA. Using the numeric hue values from the software eliminates the variations in human color perception. Intra and interrater reliability of the visual and computer-assisted counting methods were evaluated with Spearman's. The authors found statistical significance in the intrarater reliability (r = 1.0, P = 0.0001 for all chromatin categories) and interrater reliability (r = 0.975, P = 0.005 for both readings) when using the software program. No statistical significance was found for the visual counting method, indicating inaccuracy between and within raters. Thus, the computer-assisted counting method of identifying the damaged DNA is more accurate and precise than the individual's visual perception of color. Based on these data, apoptosis measurements using color staining with EB and AO should be determined using hue values generated by a computer program and not by a researcher's visual assessment.

Acridine Orange↗
PubMed2005

Pressure-support ventilation and diaphragm shortening in the rat model.

Little is known about how pressure-support ventilation affects diaphragm performance because there is no direct measurement of diaphragm function in the clinical setting. An indicator of diaphragm performance or work is the product of diaphragm muscle shortening and intrathoracic pressure during inspiration. We studied the effect of pressure-support ventilation on diaphragm shortening, diaphragm work, and other cardiopulmonary parameters. In 15 anesthetized Sprague-Dawley male rats, pressure support was increased from 0 to 10 cm H2O in 2 cm increments. Increasing pressure support from 0 to 10 cm H2O resulted in respiratory rate decreasing 25%, tidal volume increasing 148%, minute ventilation increasing 91%, end-tidal carbon dioxide decreasing 5%, and cardiac output decreasing 30%. Progressively increasing pressure support to 10 cm H2O was accompanied by decreases in the end-inspiratory pressure without significant increases in diaphragm shortening. Therefore, diaphragm work was decreased. The lack of an increase in diaphragm shortening in the presence of an increase in tidal volume indicated that there was an augmentation of thoracic volume in the coronal and/or horizontal axes instead of the cephalocaudal axes throughout inspiration. These findings may be useful to nurse anesthetists in the understanding of diaphragm work when patients are being ventilated with pressure-support ventilation.

Animals↗
PubMed2004

Apoptosis: understanding the new molecular pathway.

Advances in science have increased the knowledge of how cells die in the body (apoptosis). A basic understanding of this process can improve nurses' ability to review new scientific literature and enable them to provide safer bedside care.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Increased ocular blood vessel numbers and sizes following chronic sympathectomy in rat.

Disease states characterized by ocular vascular pathology are often associated with impaired sympathetic function. This study examined the effect of sympathetic denervation on ocular vasculature of the adult rat. Uveal perfusion and choroidal and retinal blood vessel sizes and numbers were assessed in rats with intact innervation and after short- (2 days) or long-term (6 weeks) sympathetic denervation induced by ipsilateral superior cervical ganglion excision. In rats with intact innervation and after short-term sympathectomy, blood flow in both eyes was comparable. However, after long-term sympathectomy, blood flow was four-fold greater in the denervated than in the innervated eye, but was unaltered in lacrimal gland, cerebral cortex, and masseter muscle. Choroid surface area was not affected by long-term sympathectomy, but choroidal thickness was increased and choroidal cross-sectional area occupied by vascular lumina was greater. Arteriolar number per unit cross-sectional area of choroid was not altered although arteriolar diameters were enlarged. Choroidal venules were larger and more abundant. Choroidal capillary numbers were unchanged, but retinal capillaries of the outer plexiform layer were increased. To determine if these changes result from loss of sympathetic activity, sympathetic preganglionic innervation was excised chronically. This produced significant increases in choroidal thickness and vascular luminal area, and in numbers of arterioles, small venules, and capillaries in the outer plexiform layer. These findings show that sympathetic innervation is critical in regulating choroidal and retinal vascularity, and that chronic loss of sympathetic activity may contribute to abnormal vascular proliferation in diseases such as age-related macular degeneration and diabetic retinopathy.

Animals↗
PubMed2002

Treatment and prevention of diaphragm fatigue using low-dose dopamine.

There is increasing evidence that diaphragm fatigue is a major cause of failure in weaning patients from mechanical ventilation. Patients in intensive care units are often administered dopamine to improve renal blood flow without regard to its effect on diaphragm blood flow. The aim of this study was to investigate if intravenous low-dose dopamine, equivalent to the dose used in intensive care units, can treat and prevent diaphragm fatigue. Diaphragm fatigue was produced in anesthetized rats by inspiratory resistance loading (IRL). The effect on diaphragm shortening, diaphragm blood flow, and aortic blood flow was determined. When diaphragm fatigue was attained, group I was given saline for 30 min while maintaining IRL. At the time of diaphragm fatigue, group II was given low-dose dopamine (2 microg/kg/min) for 30 min while maintaining IRL. In group III, dopamine administration was started before and continued throughout the period of IRL. Administering dopamine after the development of diaphragm fatigue (group II) increased diaphragm performance as measured by increased diaphragm shortening and was accompanied by an increased diaphragm blood flow. Administering dopamine prior to and throughout IRL (group III) prevented diaphragm fatigue. Low-dose dopamine can prevent and/or reverse diaphragm fatigue in rats without a significant change in aortic blood flow. This effect of dopamine may be due to increased oxygen delivery associated with the increased diaphragm blood flow, resulting in less free radical formation and thus less muscle damage.

Animals↗
PubMed2002

Oxidative stress in critically ill patients.

Oxygen-derived free radicals play an important role in the development of disease in critically ill patients. Normally, oxygen free radicals are neutralized by antioxidants such as vitamin E or enzymes such as superoxide dismutase. However, in patients who require intensive care, oxygen free radicals become a problem when either a decrease in the removal or an overproduction of the radicals occurs. This oxidative stress and the damage due to it have been implicated in many diseases in critically ill patients. Many drugs and treatments now being investigated are directed toward preventing the damage from oxidative stress. The formation of reactive oxygen species, the damage caused by them, and the body's defense system against them are reviewed. New interventions are described that may be used in critically ill patients to prevent or treat oxidative damage.

Antioxidants↗
PubMedDate not supplied

The effect of dobutamine infusion on fractional diaphragm thickening and diaphragm blood flow during fatigue.

BACKGROUND: Diaphragm fatigue (DF) has been implicated in respiratory failure in diseases that increase inspiratory resistance loading (IRL) and may complicate weaning of patients from mechanical ventilation. OBJECTIVE: The purpose of this study was to examine the effects of dobutamine administration (10 micro g/kg/min) on DF and to identify the mechanisms by which dobutamine augments diaphragm shortening and diaphragm blood flow (DBF) during fatigue with a rat model. METHODS: The study had an experimental design with 3 groups of Sprague-Dawley rats (n = 38) with 4 experimental periods: period 1, control; period 2, application of IRL; period 3, treatment; and period 4, recovery. DF was produced via IRL. During period 3 treatment, normal saline solution was infused in group I, dobutamine in group II, and dobutamine plus butoxamine hydrochloride in group III. The percent change in fractional diaphragm thickness (FDT) during inspiration reflected diaphragm shortening. DBF and aortic blood flow were determined with fluorescent microspheres. Diaphragm vascular resistance and systemic vascular resistance were calculated on the basis of Poiseuille's equation. RESULTS: Results indicated infusion of dobutamine increased FDT (P =.01) and DBF (P =.009) with respect to fatigue levels. The effects of dobutamine on FDT and DBF were attenuated with infusion of butoxamine hydrochloride (a beta-2 adrenoceptor antagonist) with respect to fatigue. CONCLUSION: Administration of dobutamine at a rate similar to that used clinically increased diaphragm muscle contractility (FDT) and DBF in diaphragms fatigued by IRL. The dobutamine effect on FDT may be the result of restoration of the balance between diaphragm energy consumption and energy delivery to the diaphragm by increasing DBF. Butoxamine hydrochloride attenuated the dobutamine-induced increase in DBF, indicating dobutamine produced vasodilatation via beta-2 adrenoceptors. Thus, the administration of intravenous dobutamine may be a useful adjunct in the treatment of DF.

Animals↗
PubMedDate not supplied

The role of apoptosis in respiratory diseases.

PURPOSE: The purpose of this article is to define apoptosis and describe how this cellular pathway is relevant to the pathogenesis of different respiratory diseases. This will assist clinical nurse specialists in understanding how new drugs and therapies inhibit and stimulate apoptotic pathways. BACKGROUND: Clinical nurse specialists need to expand their knowledge concerning the role of apoptosis so that they can better expand their spheres of influence. The 4 stages of apoptosis are discussed, as well as the various apoptotic pathways involved with asthma, emphysema, and acute respiratory distress syndrome that promote and inhibit apoptosis in patients. CONCLUSION: It is crucial for clinical nurse specialists to know what apoptosis is and how it relates to different pathophysiologic states. The challenge facing clinical nurse specialists is how to be kept informed and current concerning molecular and cellular mechanisms that are important in the practice setting. Strategies needed to maintain expertise include acquiring new knowledge, developing new skills, and changing attitudes about molecular biology. Apoptosis must become a significant part of any health professionals' continuing educational program because it has been recognized as the pathway to most any disease. Clinical nurse specialists who understand apoptosis and its pathways can use this knowledge to aid in the prevention and treatment of respiratory diseases.

Apoptosis↗
PubMedDate not supplied

Understanding renal dose dopamine.

Low-dose dopamine is a widely administered drug used often in critical care settings to prevent or treat patients with low urinary output. There are new data to support that low-dose dopamine may have side effects and not always increase renal perfusion to the kidneys. This article is a review of the current use of low-dose dopamine, the role of dopamine in the kidneys, and the potential risks of infusing this drug to patients.

Cardiotonic Agents↗