Biomedical subjects

R A Berg

Publications and source records attributed to R A Berg.

At least 55 records · Page 3Linked to original sources

PubMed1995

Bystander cardiopulmonary resuscitation. Concerns about mouth-to-mouth contact.

BACKGROUND: Bystander cardiopulmonary resuscitation (CPR) is performed on only a small percentage of patients who suffer cardiac arrest. We conducted a study to elucidate attitudes toward and potential obstacles to performance of bystander CPR. METHODS: Attitude survey of 975 people on the University Heart Center, University of Arizona, Tucson, mailing list. Participants were asked about their willingness to perform CPR under four conditions, with varying relationships (stranger vs relative or friend) and CPR techniques (chest compressions plus mouth-to-mouth ventilation [CC+V] vs chest compressions alone [CC]). RESULTS: Participants rated willingness to perform CPR and concern about disease transmission. Both relationship and CPR technique affected willingness to respond. Only 15% would "definitely" provide CC+V with strangers compared with 68% who would "definitely" perform CC. Even with relatives or friends, only 74% would "definitely" provide CC+V compared with 88% who would "definitely" provide CC. Eighty-two percent of participants were at least "moderately" concerned about disease transmission. CONCLUSION: Concerns regarding mouth-to-mouth ventilation appear to create substantial barriers to performance of bystander CPR. Intensified educational efforts and investigations of new approaches to bystander CPR are warranted.

Adult↗

PubMed1995

The need for ventilatory support during bystander CPR.

STUDY OBJECTIVE: To compare CPR with chest compressions plus ventilatory support (CC+V) and chest compressions alone (CC). DESIGN: Prospective, randomized study. SETTING: Research laboratory. INTERVENTIONS: After 2 minutes of ventricular fibrillation, 18 domestic swine (20 to 35 kg) were treated first with CC or CC+V for 10 minutes, then with standard advanced cardiac life support. RESULTS: Hemodynamics, survival, and neurologic outcome were determined. All 8 swine subjected to CC+V and all 10 subjected to CC showed return of spontaneous circulation. One animal in each group died within 1 hour. Seven of 8 animals in the CC+V group survived for 24 and 48 hours, compared with 9 of 10 CC animals at 24 hours and 8 of 10 at 48 hours. All 48-hour survivors were neurologically normal. CONCLUSION: In this experimental model of bystander CPR, we could not detect a difference in hemodynamics, 48-hour survival, or neurologic outcome when CPR was applied with and without ventilatory support.

Animals↗

PubMed1995

Chest compression and ventilation rates during cardiopulmonary resuscitation: the effects of audible tone guidance.

OBJECTIVES: To determine: 1) whether chest compressions during CPR are being performed according to American Heart Association (AHA) guidelines during cardiac arrest; and 2) the effect of an audio prompt to guide chest compressions on compliance with AHA guidelines and hemodynamic parameters associated with successful resuscitation. METHODS: An observational clinical report and laboratory study was conducted. A research observer responded to a convenience sample of cardiac arrests within a 300-bed hospital and counted the rate of chest compressions and ventilations during CPR. To evaluate the effect of an audio prompt on CPR, health care providers performed chest compression without guidance using a porcine cardiac arrest model for 1 minute, followed by a second minute in which audio guidance was added. Chest compression rates, arterial and venous blood pressures, end-tidal CO2 (ETCO2) levels, and coronary perfusion pressures were measured and compared for the two periods. RESULTS: Twelve in-hospital cardiac arrests were observed in the clinical part of the study. Only two of 12 patients had chest compressions performed within AHA guidelines. No patient had respirations performed within AHA guidelines. In the laboratory, 41 volunteers were tested, with 66% performing chest compressions outside the AHA standards for compression rate without audible tone guidance. With guided chest compressions, the mean (+/- SD) chest compression rate increased from 74 +/- 22 to 100 +/- 3/min (p < 0.01). End-tidal CO2 levels increased from 15 +/- 7 to 17 +/- 7 torr (p < 0.01). Coronary perfusion pressure increased minimally with audible tone-guided chest compressions. CONCLUSIONS: The majority of Basic Cardiac Life Support--certified health care professionals did not perform CPR according to AHA-recommended guidelines. The use of audible tones to guide chest compression resulted in significantly higher chest compression rates and ETCO2 levels.

American Heart Association↗

PubMed1995

Antegrade cannulation of radial artery in infants and children.

We describe the novel approach of antegrade radial artery cannulation in five pediatric patients after failure of standard retrograde cannulation by percutaneous and cutdown technique. This antegrade cannulation led to successful, reliable continuous blood pressure monitoring and arterial blood sampling without complications. We believe antegrade cannulation can be successfully used when radial arteries are obstructed and retrograde blood flow is observed during failed cutdown attempts at standard retrograde arterial cannulation.

Adolescent↗

PubMed1994

Toxic encephalopathy due to 1,1,1-trichloroethane exposure.

Twenty-eight workers with long-term repetitive high exposures to 1,1,1-trichloroethane were evaluated for complaints of short-term memory loss, disequilibrium, moodiness, irritability, and decreased ability to concentrate. As a group, they had significant deficits in memory, intermediate memory, rhythm, and speed as measured by the Luria-Nebraska Neuropsychological Battery. Platform posturography demonstrated deficits in vestibular, somatosensory, and ocular components of balance. The encephalopathic picture in these patients is similar to what has been described after exposure to other solvents.

Adult↗

PubMed1994

Effect of electromagnetic stimulation with different waveforms on cultured chick tendon fibroblasts.

An energy efficient electromagnetic stimulator device for fracture healing was compared to a commercially available device in stimulating cell growth in tissue cultures. The energy efficient device, which conserves energy by using a bidirectional time-dependent magnetic wave form, and the commercially available stimulator, which uses a unidirectional time-dependent magnetic wave form, were tested on chick tendon fibroblasts in primary culture. Comparing non-stimulated control and cells electromagnetically stimulated with unidirectional and bidirectional waveforms showed that at the growth phase between days 2 and 3, both electrical stimulation techniques increased cell division as measured by DNA synthesis. When cells were dividing rapidly, collagen synthesis was reduced. When the cells reached the confluence there was no difference among the groups (control, unidirectionally stimulated, and bidirectionally stimulated) in terms of number of cells or collagen produced.

Animals↗

PubMed1994

A method for quantitative image assessment based on redundant feature measurements and statistical reasoning.

Advances in computer graphics and electronics have contributed significantly to the increased utilization of digital imaging throughout the scientific community. Recently, as the volume of data being gathered for biomedical applications has begun to approach the human capacity for processing, emphasis has been placed on developing an automated approach to assist health scientists in assessing images. Methods that are currently used for analysis often lack sufficient sensitivity for discriminating among elements that exhibit subtle differences in feature measurements. In addition, most approaches are highly interactive. This paper presents an automated approach to segmentation and object recognition in which the spectral and spatial content of images is statistically exploited. Using this approach to assess noisy images resulted in correct classification of more than 97% of the pixels evaluated during segmentation and in recognition of geometric shapes irrespective of variations in size, orientation, and translation. The software was subsequently used to evaluate digitized stained blood smears.

Algorithms↗

PubMed1994

Local fibrinolysis in cerebral venous thrombosis.

Extensive cerebral venous sinus thrombosis may cause death or severe neurologic sequelae. A minimally responsive 10-year-old boy with thrombosis of the superior sagittal sinus, left transverse and left sigmoid sinus, torcular, vein of Galen, and straight sinus underwent fibrinolytic therapy with urokinase during transfemoral venous angiography. He improved dramatically during the procedure as antegrade venous flow was re-established. Local thrombolytic therapy may be beneficial for other patients with rapid neurologic deterioration caused by extensive thrombosis of superficial and deep venous structures.

Cerebral Angiography↗

PubMed1994

Complex atrial tachycardias and respiratory syncytial virus infections in infants.

Respiratory syncytial virus (RSV), a common cause of respiratory infections in children, has only rarely been associated with acquired heart disease. We reviewed hospital charts, rhythm strips, and electrocardiograms of 8 infants with abnormal supraventricular tachycardia (SVT), > 250 beats/min, associated with acute RSV infections. Cultures of nasopharyngeal specimens from six of eight infants grew RSV. Two infants with negative viral culture results had symptoms typical of an RSV infection during a documented RSV epidemic. Two infants had congenital heart defects. Seven of the eight infants had an ectopic atrial tachycardia, chaotic atrial tachycardia, or atrial flutter, and five of eight had episodes of nonsustained wide-complex SVT. One patient was initially treated with intravenously administered lidocaine for an incorrect diagnosis of ventricular tachycardia. SVT was unrelated to either beta-agonist therapy or hypoxic episodes. SVT did not recur after discharge in any infant with a structurally normal heart. Both patients with structural heart disease had recurrences of SVT. We conclude that RSV infections in infants may be associated with unusual atrial tachycardias and that the diagnosis may be complicated by episodes of nonsustained, wide-complex tachycardias. In patients with RSV and structurally normal hearts, chaotic and ectopic atrial tachycardias are self-limited and do not require prolonged drug therapy.

Atrial Flutter↗

PubMed1994

The efficacy of an ACLS training program for resuscitation from cardiac arrest in a rural community.

STUDY OBJECTIVE: To determine whether an advanced cardiac life support (ACLS) course in a rural hospital will improve resuscitation success from cardiac arrest. DESIGN: A retrospective case review of all patients in cardiac arrest during a 13-month period before and after the institution of an ACLS training program. SETTING: Emergency department of a 42-bed rural, community hospital in a community with no prehospital advanced life support or early defibrillation. PARTICIPANTS: All patients in cardiac arrest were entered into the data base. Twenty-nine patients were included in the pre-ACLS period and 35 in the post-ACLS period. There were no significant differences in age, gender, initial rhythm, comorbid diseases, witnessed versus unwitnessed arrest, or total arrest time in the patients in the pre-ACLS period compared with those in the post-ACLS period. INTERVENTION: ACLS provider training. MAIN RESULTS: Patients in cardiac arrest who had ventricular fibrillation/tachycardia as their initial rhythm had significant improvement in resuscitation success compared with patients in ventricular fibrillation/tachycardia in the pre-ACLS period (six of 15 versus none of nine, P < .05). Out-of-hospital cardiac arrest resuscitation was more successful in the post-ACLS period than in the pre-ACLS period (five of 30 versus none of 25, P < .05). Overall, seven of 35 patients (20%) were resuscitated successfully in the post-ACLS period, with two patients surviving to hospital discharge. This was not significantly different than the two of 29 patients (7%) resuscitated in the pre-ACLS period, with one patient surviving to discharge. CONCLUSION: The institution of an ACLS-provider course in a rural community hospital was associated with improvement in initial resuscitation for patients with ventricular fibrillation/tachycardia and out-of-hospital arrest.

Cardiopulmonary Resuscitation↗

PubMed1994

Femoral venous pulsations during open-chest cardiac massage.

We describe the cases of two children with easily palpated femoral pulses during open-chest cardiac massage after aortic occlusion. These pulsations must have arisen from the femoral veins, implying that during CPR in children the usual anatomic landmarks for femoral venous access may be unreliable, and femoral pulsations do not necessarily reflect arterial flow. Femoral pulses may signify to-and-fro inferior vena caval flow that compromises venous return, adversely affecting cardiac output and the effectiveness of medication administration to the lower extremity.

Aorta↗

PubMed1994

High-dose epinephrine results in greater early mortality after resuscitation from prolonged cardiac arrest in pigs: a prospective, randomized study.

OBJECTIVE: To determine whether high-dose epinephrine (0.2 mg/kg) during cardiopulmonary resuscitation (CPR) results in improved outcome, compared with standard-dose epinephrine (0.02 mg/kg). DESIGN: A prospective, randomized, blinded study. SETTING: Research laboratory of a university medical center. SUBJECTS AND INTERVENTIONS: Thirty domestic swine were randomized to receive standard- or high-dose epinephrine during CPR after 15 mins of fibrillatory cardiac arrest. Three minutes of CPR were provided, followed by advanced cardiac life support per American Heart Association guidelines. Animals that were successfully resuscitated were supported for 2 hrs in an intensive care unit (ICU) setting, and then observed for 24 hrs. MEASUREMENTS AND MAIN RESULTS: Electrocardiogram, aortic blood pressure, right atrial blood pressure, and end-tidal CO2 were monitored continuously until the intensive care period ended. Survival and neurologic outcome were determined. Return of spontaneous circulation was attained in 14 of 15 animals in each group. Four of 14 high-dose epinephrine pigs died during the ICU period after return of spontaneous circulation vs. zero of the 14 standard-dose pigs (p < .05). Six standard-dose pigs survived 24 hrs vs. four high-dose pigs. Twenty-four-hour survival rate and neurologic outcome were not significantly different. Within 10 mins of defibrillation, severe hypertension (diastolic pressure > 120 mmHg) occurred in 12 of 14 high-dose pigs vs. two of 14 standard-dose pigs (p < .01). Severe tachycardia (heart rate > 250 beats/min) occurred in seven of 14 high-dose pigs vs. zero of 14 standard-dose pigs (p < .01). All four high-dose epinephrine pigs that died during the ICU period experienced both severe hypertension and tachycardia immediately postresuscitation. CONCLUSIONS: High-dose epinephrine did not improve 24-hr survival rate or neurologic outcome. Immediately after return of spontaneous circulation, most animals in the high-dose epinephrine group exhibited a hyperadrenergic state that included severe hypertension and tachycardia. High-dose epinephrine resulted in a greater early mortality rate.

Animals↗

PubMed1994

Activation of alveolar macrophages by native and synthetic collagen-like polypeptides.

Interstitial connective tissue fragments are known to be chemotactic for neutrophils and these have been implicated in mediating the migration of inflammatory cells to the lung following injury. In the present studies, we determined if degradation products of collagen also induced chemotaxis and functional activation of alveolar macrophages. For these studies, we used bovine dermal collagen digested with bacterial collagenase or cyanogen bromide and small molecular weight synthetic polypeptides containing proline (Pro), glycine (Gly), and hydroxyproline (Hyp). We found that collagenase or cyanogen bromide digests of native collagen, as well as synthetic polypeptides containing Pro and Gly in the pentameric (Pro-Pro-Gly)5 form, were potent chemoattractants for rat alveolar macrophages inducing migration in the nanomolar concentration range. We also found that native and synthetic collagen peptides stimulated the release of superoxide anion and hydrogen peroxide, as well as elastase and gelatinase release from alveolar macrophages. These effects were dose and time dependent, reaching a maximum after 72 h with 0.1 to 1 microM peptides. In contrast to chemotaxis, synthetic peptides containing Hyp also stimulated reactive oxygen intermediate and elastase release from the cells. Although the pentameric and decameric forms of the synthetic peptides were equally effective in stimulating elastase release, (Pro-Pro-Gly)5 and (Pro-Hyp-Gly)5 peptides were more active in inducing a respiratory burst. We also determined if alveolar macrophages were activated for cytotoxicity by collagen peptides. Treatment of the macrophages with native collagen digests or (Pro-Pro-Gly)5 was found to induce cytotoxicity of these cells towards both transformed and nontransformed rat-derived targets.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1993

Molecular analysis of chicken embryo SPARC (osteonectin).

SPARC is a secreted glycoprotein that modulates cell shape and cell-matrix interactions. Levels of SPARC are increased at sites of somitogenesis, osteogenesis, and angiogenesis in the embryo and during wound repair in the adult. We have cloned and characterized SPARC from chicken embryo. A 2.2-kbp cDNA, obtained by a novel use of the polymerase chain reaction, was determined to encode a 298-residue protein that is 85% identical to human SPARC. Antigenic sites in particular appear to be highly conserved, as antibodies against C-terminal sequences of murine and bovine SPARC reacted with a 41-43 kDa protein in chicken embryo extracts. Chicken SPARC can be defined by four sequence signatures: (a) a conserved spacing of 11 cysteine residues in domain II, (b) the pentapeptide KKGHK in domain II, which is contained within a larger region of 31 identical residues, (c) a 100% conserved region of 10 residues in domain III, and (d) a C-terminal, calcium-binding EF-hand motif. SPARC mRNAs in the 10-day-old chicken embryo are represented by three sizes of 1.8, 2.2 and 3.0 kb. The relative steady-state levels for the 2.2-kb mRNA were determined as aorta > or = skeletal muscle > calvarium > vertebra > anterior limb > kidney > heart > brain > skin and lung >> liver. The relative abundance of the 1.8-kb and 2.2-kb mRNAs varied among tissues and indicated that differential processing of SPARC mRNAs might occur. All three RNA species were detected by a cDNA probe for the N-terminal part of the coding region. Thus, the three mRNA species appear to arise from differential 3' splicing and/or polyadenylation. Collective evidence demonstrates that SPARC has been well-conserved during vertebrate evolution, a finding that indicates a fundamental role for this protein in development.

Amino Acid Sequence↗

PubMed1993

Differential induction of stromelysin mRNA by bovine articular chondrocytes treated with interferon-gamma and interleukin-1 alpha.

Articular chondrocytes from rheumatoid joints have been shown to express class II major histocompatibility (MHC) antigens that were correlated with the presence of interferon-gamma (IFN-gamma) in the inflamed joint. Chondrocytes expressing MHC antigens function as antigen presenting cells and thus stimulate lymphocyte proliferation. These responses suggest a powerful role for the IFN-gamma stimulation of chondrocytes. The present studies were designed to examine the functional role of chondrocytes exposed to IFN-gamma during cartilage degradation that occurs in synovial disease. Destruction of cartilage in arthritis is partially attributable to metalloproteinases released by the chondrocytes in response to interleukin-1 (IL-1). Bovine articular chondrocytes treated with interleukin-1 alpha (IL-1 alpha) produced enhanced levels of stromelysin mRNA, however, Northern blots could not determine the percentage of cells responding. Exposure of bovine articular chondrocytes to IFN-gamma induced the expression of bovine HLA-DR (boHLA-DR) antigen in 50% of the cells. Using a modified cell sorting technique, chondrocytes that expressed class II MHC antigens produced two fold greater stromelysin mRNA than chondrocytes that did not express this antigen. In contrast, collagen type II mRNA levels were similar in chondrocytes, regardless of the expression of class II MHC antigens. In situ hybridization studies showed that less than half of all cartilage chondrocytes were induced to synthesize stromelysin mRNA. These observations suggest that IFN-gamma stimulates specific subpopulations of chondrocytes to be functionally active in inflammation-induced metalloprotease secretion.

Animals↗

PubMed1993

Regulation of collagen synthesis in human dermal fibroblasts in contracted collagen gels by ascorbic acid, growth factors, and inhibitors of lipid peroxidation.

Ascorbic acid has been shown to stimulate collagen synthesis in monolayer cultures of human dermal fibroblasts. In the present studies, we examined whether the presence of a collagen matrix influences this response of dermal fibroblasts to ascorbic acid. Fibroblasts and collagen were mixed and allowed to gel and contract for 6 days to form a matrix prior to determining the concentration and time dependence for ascorbic acid to affect collagen synthesis by fibroblasts within the matrix. Collagen synthesis was stimulated at levels at or above 10 microM ascorbic acid and was maximal after 2 days of treatment. This concentration and time dependence is similar to that of cells grown in monolayer cultures. The effects of transforming growth factor-beta (TGF-beta) and fibroblast growth factor (FGF) were also examined in this model. TGF-beta increased and FGF inhibited collagen synthesis in the gels, as has been shown for cells in monolayer cultures. The effects of potential inhibitors of lipid peroxidation induced by ascorbic acid were also examined in these matrices and compared to previous results obtained in monolayer cultures. Propyl gallate, cobalt chloride, alpha,alpha-dipyridyl, and alpha-tocopherol inhibited the ascorbic acid-mediated stimulation of collagen synthesis while mannitol had no effect. Natural retinoids inhibited total protein synthesis without the specific effect on collagen synthesis that was seen in monolayer cultures. These results indicate that ascorbic acid stimulates collagen synthesis in fibroblasts grown in a collagen matrix in a manner similar to that found in monolayer cultures. In contracting collagen gels, however, the magnitude of the effect is less and retinoids do not specifically inhibit collagen synthesis.

2,2'-Dipyridyl↗

PubMed1993

Medications in neonatal resuscitation.

Medication usage in neonatal resuscitation has been largely extrapolated from adult resuscitation guidelines. Compared to older children and adults, newborn infants have major anatomical and physiological differences which affect their need for and response to medications during resuscitation. This article discusses some of these differences, highlights the discussion of the Emergency Cardiac Care Panel for Neonatal Pharmacology, lists the recommendations of the panel to the Emergency Cardiac Care Committee, and discusses areas of future research in neonatal resuscitation.

Aging↗

PubMed1993

Dobutamine infusions in stable, critically ill children: pharmacokinetics and hemodynamic actions.

OBJECTIVE: To delineate dobutamine pharmacokinetics and hemodynamic responses in children. DESIGN: Prospective, pharmacokinetic study using sequential, graded dosing of drug. INTERVENTIONS: Graded intravenous dobutamine infusions of 0.5, 2.5, 5, 10, and 20 micrograms/kg/min were sequentially administered for 25 mins each. Plasma dobutamine concentrations and echocardiographically determined hemodynamic data were obtained at baseline and at 15 and 25 mins during each infusion rate. Hemodynamic responses were evaluated by paired t-test and by computerized evaluation of individual dose-response curves. SETTING: Pediatric intensive care unit in a university setting. PATIENTS: Eleven stable, critically ill children previously requiring inotropic support with dobutamine. Seven patients were postcardiac surgical patients; four patients had acute cardiac dysfunction with septic shock and/or adult respiratory distress syndrome. MEASUREMENTS AND MAIN RESULTS: Mean cardiac index increased from 3.8 to 5.2 L/min/m2 (p < .05). Increasing the infusion rate from 10 to 20 micrograms/kg/min increased cardiac index by 16% (p < .05). Cardiac index increased by > 10% in four of seven patients at a dobutamine infusion rate of 0.5 microgram/kg/min (mean 21%). The relationship of plasma dobutamine concentration to cardiac index, systolic blood pressure, and heart rate fit a threshold model with a log-linear relationship after the threshold in seven of nine, seven of 11, and eight of 11 patients, respectively. As anticipated, in the patients who responded, there were linear increases in hemodynamic responses with exponential increases in plasma dobutamine concentrations. Mean plasma clearance rate was 82 +/- 3 mL/min/kg. First-order kinetics were demonstrated by the direct linear relationship of plasma dobutamine concentration to infusion rate (mean r2 = .95; p < .01 for each patient) and by independence of clearance from dose and duration of each infusion. CONCLUSIONS: Dobutamine effectively improves systolic function in critically ill children. Hemodynamic responses to dobutamine generally follow a predicted log-linear dose-response model. Dobutamine clearance in this study was consistent with first-order kinetics. The wide variability in hemodynamic responses and clearance kinetics indicate that dobutamine infusions must be titrated individually.

Adolescent↗