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Biomedical subjects

C E Smith

Publications and source records attributed to C E Smith.

At least 37 records · Page 2Linked to original sources
PubMed2001

Family Caregivers' Motives for Helping Scale derived from motivation-to-help theory.

The literature does not contain a measure of family caregivers' motives for helping provide daily complex home care. Such a measure will permit nurses to assess and provide interventions specific to each caregiver's motivation for helping. The purpose of this study was to apply Batson's empirically derived helping pathway theory to the measurement of caregiver motives for helping and develop a short form that does not add to the burden of caregiving. A Principal Components factor analysis (N = 93) of Family Caregivers' Motives for Helping Scale is used. Criterion-related validity is ascertained using a triangulated, independent validation procedure with qualitative data from a subsample (N = 41). Subsample subjects' interview data were categorized, based on Batson's theoretical pathway definitions, by coders blinded to caregiver Motives for Helping Scale scores. Three of Batson's four helping pathways (reward seeking, altruism, and punishment-avoidance) were extracted during factor analysis. This three-factor solution explained 66.6% of the variance and was confirmed by a 97% agreement between three of Batson's pathways and caregivers' helping motive score. The content analyses of the descriptive interview data also coincide with the 3-factor solution. The scale items representing Batson's fourth helping pathway, distress reaction, were not retained due to cross loading. The Family Caregivers' Motives for Helping Scale accurately measures three of four theoretically derived motivations for helping another. The scale should be reanalyzed in a larger sample of caregivers. Aligning nursing interventions to caregiver motives for helping can provide reinforcement for caregivers and potentially enhance home care outcomes.

Caregivers↗
PubMed2001

National health expenditures, 1999.

The health care spending share of gross domestic product (GDP) remained steady between 1993 and 1999 as moderate-to-strong economic growth coincided with a rapid shift to managed care. This shift, along with decelerating growth in Medicare spending, appears to have generated a mostly one-time saving that lowered aggregate health expenditure growth.

Advertising↗
PubMed2001

Perioperative nursing education: the operating room as a learning climate.

Perioperative patient care presents a demand for registered nurses with competence, skills, and experience. Without a well-grounded educational program, the novice perioperative nurse is often overwhelmed at the learning demands of the perioperative practice setting. Settings in which invasive and other operative procedures are carried out present a variety of challenges in orienting the novice nurse. There must be educational resources, coaching and support for novices who have limited real-world operating room experience, and work environments that encourage and foster professional development and a learning culture. An orientation program that focuses on the tenets of learning rather than seeing and doing without understanding holds the most promise for both recruitment and retention of perioperative nurses.

Career Choice↗
PubMed2000

Sevoflurane mask anesthesia for urgent tracheostomy in an uncooperative trauma patient with a difficult airway.

PURPOSE: Proper care of the trauma patient often includes tracheal intubation to insure adequate ventilation and oxygenation, protect the airway from aspiration, and facilitate surgery. Airway management can be particularly complex when there are facial bone fractures, head injury and cervical spine instability. CLINICAL FEATURES: A 29-yr-old intoxicated woman suffered a motor vehicle accident. Injuries consisted of multiple abrasions to her head, forehead, and face, right temporal lobe hemorrhage, and complex mandibular fractures with displacement. Mouth opening was <10 mm. Blood pressure was 106/71 mm Hg, pulse 109, respirations 18, temperature 37.3 degrees C, SpO2 100%. Chest and pelvic radiographs were normal and the there was increased anterior angulation of C4-C5 on the cervical spine film. Drug screen was positive for cocaine and alcohol. The initial plan was to perform awake tracheostomy with local anesthesia. However, the patient was uncooperative despite sedation and infiltration of local anesthesia. Sevoflurane, 1%, inspired in oxygen 100%, was administered via face mask. The concentration of sevoflurane was gradually increased to 4%, and loss of consciousness occurred within one minute. The patient breathed spontaneously and required gentle chin lift and jaw thrust. A cuffed tracheostomy tube was surgically inserted without complication. Blood gas showed pH 7.40, PCO2 35 mm Hg, PO2 396 mm Hg, hematocrit 33.6%. Diagnostic peritoneal lavage was negative. Pulmonary aspiration did not occur. Oxygenation and ventilation were maintained throughout the procedure. CONCLUSION: Continuous mask ventilation with sevoflurane is an appropriate technique when confronted with an uncooperative trauma patient with a difficult airway.

Adult↗
PubMed2000

A qualitative comparison of some diffusion models for neural activity via stochastic ordering.

A number of diffusion processes have been proposed as a continuous analog of Stein's model for the subthreshold membrane potential of a neuron. Interspike intervals are then described as the first-passage-time of the corresponding diffusion model through a suitable threshold. Various biological considerations suggest the use of more sophisticated models in lieu of the Ornstein-Uhlenbeck model. However, the advantages of the additional complexity are not always clear. Comparisons among different models generally use numerical methods in specific examples without a general sensitivity analysis on the role of the model parameters. Here, we compare the distribution of interspike intervals from different models using the method of stochastic ordering. The qualitative comparison of the role of each parameter extends the results obtained from numerical simulations. One result on neurons with high positive net excitation is that the reversal potential models considered do not greatly differ from the Ornstein-Uhlenbeck model. For neurons with increased inhibition, the models give greater differences among the interspike interval distributions. In particular, when the mean trajectories are matched, the Feller model gives shorter times than the Ornstein-Uhlenbeck model but longer times than our double reversal potential model.

Action Potentials↗
PubMed2000

Conditions for noise reduction and stable encoding of spatial structure by cortical neural networks.

Cortical circuits have been proposed to encode information by forming stable spatially structured attractors. Experimentally in the primary somatosensory cortex of the monkey, temporally invariant stimuli lead to spatially structured activity patterns. The purpose of this work is to study a recurrent cortical neural network model with lateral inhibition and examine what effect additive random noise has on the networks' ability to form stable spatially structured representations of the stimulus pattern. We show numerically that this network performs edge enhancement and forms statistically stationary, spatially structured responses when the lateral inhibition is of moderate strength. We then derive analytical conditions on the connectivity matrix that ensure stochasticly stable encoding of the stimulus spatial structure by the network. For stimuli whose strength falls in the near linear region of the sigmoid, we are able to give explicit conditions on the eigenvalues of the connection matrix. Finally, we prove that a network with a connection matrix, where the total excitation and inhibition impinging upon a neural unit are nearly balanced, will yield stable spatial attractor responses.

Animals↗
PubMed2000

Sevoflurane-N2O versus propofol/isoflurane-N2O during elective surgery using the laryngeal mask airway in adults.

STUDY OBJECTIVES: To compare a sevoflurane-nitrous oxide (N2O) general anesthetic technique with a standard technique of propofol for induction, and isoflurane-N2O for maintenance. DESIGN: Prospective, randomized study. SETTING: University-affiliated tertiary-care hospital. PATIENTS: 62 adults undergoing elective surgery using the laryngeal mask airway (LMA). INTERVENTIONS: Patients received either the standard technique of propofol for induction and isoflurane-N2O for maintenance (controls) or sevoflurane-N2O for both induction and maintenance of general anesthesia. MEASUREMENTS: Induction and emergence times, heart rate, blood pressure, oxygen saturation, and end-tidal carbon dioxide were recorded. MAIN RESULTS: Time to loss of consciousness was faster after propofol (mean +/- SEM: 51 +/- 3 sec) than after sevoflurane-N2O (85 +/- 10 sec; p < 0.05). Ready for surgery times, were however, similar between groups (10 +/- 1 vs. 11 +/- 1 min, respectively). All patients in the control group had apnea after LMA insertion compared with 4 patients in the sevoflurane-N2O group (p < 0.05). Heart rate was lower 5 and 10 minutes after LMA insertion in the sevoflurane-N2O group (69 +/- 3 and 66 +/- 3 bpm) versus the control group (81 +/- 3 bpm and 74 +/- 3 bpm, p < 0.05). After cessation of anesthetic gases, there were no differences in time to LMA removal, eye opening, or exiting the operating room (OR) between the control group (7, 8, and 10 min) and sevoflurane-N2O groups (7, 8, and 12 min, respectively). The majority of patients in both groups (92% to 97%) rated their anesthetic experience as excellent or good. CONCLUSIONS: Sevoflurane-N2O and propofol provided comparable conditions for LMA insertion. Sevoflurane-N2O was not associated with a faster return of consciousness or faster time to exit the OR compared with isoflurane-N2O.

Adult↗
PubMed2000

Total intravenous anesthesia with a propofol-ketamine combination during coronary artery surgery.

OBJECTIVE: To evaluate the cardiovascular effects of a propofol-ketamine combination in patients undergoing coronary artery surgery. DESIGN: Prospective, randomized study. SETTING: Tertiary care teaching hospital, single center. PARTICIPANTS: Seventy-eight adult patients. INTERVENTIONS: Patients were randomly allocated to receive propofol-ketamine for induction and maintenance of anesthesia (n = 36) or fentanyl-enflurane (controls, n = 42). MEASUREMENTS AND MAIN RESULTS: Hemodynamics and other variables were recorded during and after surgery and for 24 hours in the intensive care unit. Before cardiopulmonary bypass (CPB), there was similar incidence of treatment for hypotension (42% of patients in both groups), tachycardia (propofol-ketamine, 6%; controls, 5%), and myocardial ischemia (propofol-ketamine, 3%; controls, 12%). In the propofol-ketamine group, there was a decreased requirement for inotropic agents after CPB (22% of patients) compared with controls (49% of patients; p = 0.02). There was a reduced incidence of myocardial infarctions (creatine kinase myocardial band >133 U/L) in the propofol-ketamine group compared with the control group (0% v 14%; p = 0.02; Fisher's exact test). Patients in the propofol-ketamine group were more likely to have their tracheas extubated within 8 hours of arrival in the intensive care unit compared with controls (33% v 7%; p = 0.01; Cochran-Mantel-Haenzel test). CONCLUSIONS: The propofol-ketamine combination was associated with a similar incidence of pre-CPB hypotension and ischemia, a decreased need for inotropes after CPB, an earlier time to tracheal extubation, and a reduced incidence of myocardial infarctions compared with controls.

Anesthesia, Intravenous↗
PubMed2000

The "stegosaurus" dressing: a simple and effective method of securing skin grafts in the burn patient.

Skin grafts are vulnerable to shear stress, infection, and hematoma formation during the postoperative period, all of which reduce graft survival. Various methods of dressing application and materials have been described in the literature to try and prevent graft loss. The authors report the use of the "stegosaurus dressing" (Eggcrate Pad) in 6 patients to secure skin grafts. Patients chosen were those who were either noncompliant or who sustained burns in unfavorable anatomic sites. All grafts demonstrated complete take without infection and hematoma formation. This foam dressing provides an even pressure to the recipient bed, absorbs drainage, and protects the graft from shearing. It also demonstrates the versatility to be used in difficult nonburn skin graft areas. The stegosaurus dressing is easy to apply, inexpensive, and provides a very secure dressing over the skin graft.

Burns↗
PubMed2000

Avoiding hypothermia in the trauma patient.

Hypothermia may be encountered during the management of severely injured patients, and with exception of deliberate hypothermia for neuroprotection, has been associated with increased morbidity and mortality. This review examines the recent literature with regard to risk factors for developing hypothermia, significance of hypothermia, therapeutic use of hypothermia, and invasive and noninvasive methods to prevent and treat hypothermia.

Journal Article↗
PubMed2000

Mass spectrometry of native rat amelogenins: primary transcripts, secretory isoforms, and C-terminal degradation.

Cloning technologies have established unambiguously that amelogenins always seem larger in molecular weight (Mr) by gel electrophoresis (SDS-PAGE) than by mass spectrometry (MS). This has caused many problems relating cloned versions of amelogenin to proteins actually secreted by ameloblasts in vivo. In this study, discrete protein fractions at 31-20 kDa (Mr(SDS)) were prepared from freeze-dried rat incisor enamel by techniques optimized for preserving protein integrity. N-terminal sequence and amino acid compositional analyses indicated that the major protein forming these fractions was amelogenin. As expected, the molecular weights estimated by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) MS were significantly less than their apparent molecular weights estimated by SDS-PAGE. Plots of Mr(SDS) vs. Mr(MS) for all fractions showed high linear correlation (r = 0.992). Analysis of MS data further indicated that the major protein in the 27-kDa fraction corresponded to the R180 secretory isoform of rat amelogenin, whereas some minor proteins in the 23-kDa fraction likely corresponded to a R156 secretory isoform. This was in contrast to major proteins forming the 25-, 24-, and 23-kDa fractions (Mr(SDS)), which seemed to represent proteolytic fragments of R180 progressively altered at the P169-A170, P164-L165, and F151-S152 C-terminal cleavage sites, respectively. Proteins in the 20-kDa fraction (Mr(SDS)) most closely matched by ESI-MS fragments of the R156 secretory isoform that were C-terminally-modified at the equivalent P164-L165 site.

Amelogenin↗
PubMed1999

Design, synthesis, and biological characterization of a peptide-mimetic antagonist for a tethered-ligand receptor.

Protease-activated receptors (PARs) represent a unique family of seven-transmembrane G protein-coupled receptors, which are enzymatically cleaved to expose a truncated extracellular N terminus that acts as a tethered activating ligand. PAR-1 is cleaved and activated by the serine protease alpha-thrombin, is expressed in various tissues (e.g., platelets and vascular cells), and is involved in cellular responses associated with hemostasis, proliferation, and tissue injury. We have discovered a series of potent peptide-mimetic antagonists of PAR-1, exemplified by RWJ-56110. Spatial relationships between important functional groups of the PAR-1 agonist peptide epitope SFLLRN were employed to design and synthesize candidate ligands with appropriate groups attached to a rigid molecular scaffold. Prototype RWJ-53052 was identified and optimized via solid-phase parallel synthesis of chemical libraries. RWJ-56110 emerged as a potent, selective PAR-1 antagonist, devoid of PAR-1 agonist and thrombin inhibitory activity. It binds to PAR-1, interferes with PAR-1 calcium mobilization and cellular function (platelet aggregation; cell proliferation), and has no effect on PAR-2, PAR-3, or PAR-4. By flow cytometry, RWJ-56110 was confirmed as a direct inhibitor of PAR-1 activation and internalization, without affecting N-terminal cleavage. At high concentrations of alpha-thrombin, RWJ-56110 fully blocked activation responses in human vascular cells, albeit not in human platelets; whereas, at high concentrations of SFLLRN-NH(2), RWJ-56110 blocked activation responses in both cell types. Thus, thrombin activates human platelets independently of PAR-1, i.e., through PAR-4, which we confirmed by PCR analysis. Selective PAR-1 antagonists, such as RWJ-56110, should serve as useful tools to study PARs and may have therapeutic potential for treating thrombosis and restenosis.

Base Sequence↗
PubMed1999

Dermal absorption and distribution of topically dosed jet fuels jet-A, JP-8, and JP-8(100).

Dermal exposure to jet fuels has received increased attention with the recent release of newer fuels with novel performance additives. The purpose of these studies was to assess the percutaneous absorption and cutaneous disposition of topically applied (25 microl/5 cm(2)) neat Jet-A, JP-8, and JP-8(100) jet fuels by monitoring the absorptive flux of the marker components 14C naphthalene and (3)H dodecane simultaneously applied nonoccluded to isolated perfused porcine skin flaps (IPPSF) (n = 4). Absorption of 14C hexadecane was estimated from JP-8 fuel. Absorption and disposition of naphthalene and dodecane were also monitored using a nonvolatile JP-8 fraction reflecting exposure to residual fuel that might occur 24 h after a jet fuel spill. In all studies, perfusate, stratum corneum, and skin concentrations were measured over 5 h. Naphthalene absorption had a clear peak absorptive flux at less than 1 h, while dodecane and hexadecane had prolonged, albeit significantly lower, absorption flux profiles. Within JP-8, the rank order of absorption for all marker components was (mean +/- SEM % dose) naphthalene (1.17 +/- 0.07) > dodecane (0.63 +/- 0.04) > hexadecane (0.18 +/- 0.08). In contrast, deposition within dosed skin showed the reverse pattern. Naphthalene absorption into perfusate was similar across all fuel types, however total penetration into and through skin was highest with JP-8(100). Dodecane absorption and total penetration was greatest from JP-8. Absorption of both markers from aged JP-8 was lower than other fuels, yet the ratio of skin deposition to absorption was greatest for this treatment group. In most exposure scenarios, absorption into perfusate did not directly correlate to residual skin concentrations. These studies demonstrated different absorption profiles for the three marker compounds, differential effects of jet fuel types on naphthalene and dodecane absorption, and uncoupling of perfusate absorption from skin disposition.

Administration, Topical↗