Priming the system that causes the release of cytosolic proteins in the perfused rat heart.
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2,4-Dinitrophenol↗
Biomedical subjects
S Daniels
Publications and source records attributed to S Daniels.
Blood pressure and cardiac output during exercise: a longitudinal study of children undergoing repair of coarctation.
Data were examined from 21 children who underwent graded exercise studies prior to and within 5 years after repair of coarctation. A control group of 10 normal children was also studied longitudinally on two occasions. The exercise was performed on an upright bicycle ergometer using a continuous graded exercise protocol. Parameters measured were heart rate, systolic and diastolic blood pressure at rest, and these pressures at the maximal voluntary exercise level. In addition, a subset of patients and controls had measurement of cardiac output by a modified acetylene rebreathing technique. Results indicate that coarctation patients had significant elevation of systolic and diastolic blood pressures at rest (p less than 0.001 for both) and with exercise (p less than 0.02 for both) prior to surgery. The group mean values for systolic and diastolic blood pressure did not differ from control values after surgery; however, some individuals continued to have hypertension at rest when compared to population-based norms. Heart rate, cardiac index, and stroke volume index did not differ from those of control subjects either at rest or during exercise before or after surgery. In conclusion, a group of coarctation patients studied longitudinally demonstrated marked improvement in both systolic and diastolic hypertension after surgery. The findings of normal cardiac output and stroke volume indices may have implications for the etiology of postoperative hypertension.
Aortic Coarctation↗
A controlled study of type A behavior and psychophysiologic responses to stress in anorexia nervosa.
Adolescents and young adults meeting DSM-III criteria for anorexia nervosa (n = 13) and atypical eating disorders (n = 7) were compared with weight-recovered anorectics (n = 6) and normal weight controls (n = 11) using a type-A structured interview and a computerized stress procedure. Heart rate, blood pressure, and electrocardiographic changes were monitored. Anorexia nervosa subjects demonstrated significantly more type-A characteristics than controls. The emaciated and weight-recovered anorectics had elevated hostility scores on the type-A interview, which has been shown in recent studies of type-A behavior to be a risk factor for cardiovascular disease. This pilot study is the first to demonstrate a significant relationship between anorexia and the type-A behavioral pattern. Also the anorectic subjects showed significantly more cardiovascular reactivity than controls as measured by failure of stressed anorectic subjects to lower their systolic blood pressure to baseline levels as controls did. These results support the importance of monitoring stress reactions and personality traits as well as traditional biological measures.
Adolescent↗
Biophysical characterisation of diagnostic ultrasound equipment--preliminary results.
The use of diagnostic ultrasound can be justified if it can be shown to provide only negligible or small risk while giving good benefit to the patient. In the absence of biological evidence, one way of assessing a new (or existing) piece of diagnostic equipment would be to predict the biophysical changes (i.e. heat and cavitation) that may be produced by its ultrasonic fields in tissue. An assessment of risk may then be made from our knowledge of thermal and cavitational biology. To this end, this study has sought to measure temperature rise, bubble formation, sonoluminescence and acoustic streaming arising from clinical transducers that have been carefully calibrated using a Beam Calibrator, and to determine whether there is good correlation between measured acoustic parameters in water and any of these biophysical characteristics. The results are inconclusive.
Acoustics↗
An evaluation of the structure-activity relationships of a series of analogues of mephenesin and strychnine on the response to pressure in mice.
1. A range of compounds structurally related to the centrally acting muscle relaxant mephenesin and to the chemical convulsant strychnine were synthesized and tested for their ability to alter the threshold pressures for the onset of high pressure convulsions in mice. 2. The ability of both groups of compounds to alter the threshold pressure for convulsions was found to be dependent on the nature of a simple molecular skeleton. Thus, compounds that possessed a negatively polarized group located both in the same plane as and some 4.5 A from an aromatic nucleus increased the thresholds whereas compounds with a positively polarized group at the same location reduced the thresholds. 3. These findings support the suggestion that pressure elicits convulsions via a selection action on a receptor protein complex rather than via some general perturbation of the lipid regions of cellular membranes.
Animals↗
Evaluating the success of deaf parents.
Nineteen parent-child pairs completed the Parental Strengths and Needs Inventory (PSNI) and were interviewed about their relationships. Parent and child scores on the PSNI were above average, with parents expressing high interest in information about childrearing. Interviews revealed issues specific to deaf parents, such as using children as interpreters and frustration when children had poor sign language skills. Children with good sign language skills said they were generally willing to interpret for their parents, except during conflict situations. Children also reported advantages to having deaf parents: they enjoyed being bilingual and their parents tolerated noise and loud music. Study results underscore the importance of triangulation strategies in cross-cultural research.
Adolescent↗
Minor burns: treatment using a new drug delivery system with silver sulfadiazine.
We investigated a new product for treatment of burn wounds in outpatients. The product is a drug delivery system composed of polyethylene glycol 400, poly-2-hydroxyethyl methacrylate, and dimethyl sulfoxide into which silver sulfadiazine is incorporated for sustained release. It is applied to the wound and changed every four to five days until the wound has epithelialized. Of the 20 patients we treated by this method, none had wound infections. Most patients had partial-thickness injuries that epithelialized without difficulty. One patient with full-thickness injuries required subsequent excision and grafting. Application of the product over joint surfaces facilitated range of motion. The product was easy to apply, it diminished pain, and it produced no abnormal effects except for an occasional bad odor.
Acrylates↗
Comparison of the cardiac output and stroke volume response to upright exercise in children with valvular and subvalvular aortic stenosis.
Cardiac output and stroke volume were evaluated in 17 children (mean age 11.5 +/- 3 years) with discrete, membranous subvalvular (Group I, n = 7) and valvular (Group II, n = 10) aortic stenosis during submaximal and maximal (greater than 75% predicted maximal oxygen consumption) upright cycle ergometry. Patients with valvular aortic stenosis were further subdivided on the basis of their aortic valve gradient at rest determined by cardiac catheterization (Group IIA, gradient less than 40 mm Hg; Group IIB, gradient greater than or equal to 40 mm Hg). These patients were matched with 17 control subjects on the basis of age, sex, height and intensity of exercise during maximal exertion. Cardiac and stroke indexes were determined by the acetylene rebreathing method at each exercise level. Stroke volume index in Group I was significantly greater at rest when compared with that in control subjects (69 +/- 13 versus 53 +/- 11 ml/m2, alpha = 0.01, p less than 0.05) and that in patients in Group II (69 +/- 13 versus 47 +/- 12 ml/m2, alpha = 0.01, p less than 0.05). Patients with subvalvular aortic stenosis were unable to increase their stroke volume index from rest to submaximal exercise and also decreased their stroke volume index at maximal exercise levels. In contrast, patients with mild valvular aortic stenosis (Group IIA) displayed a normal exercise response. Patients with severe valvular aortic stenosis (Group IIB) had a blunted stroke volume response at rest and at each level of exercise, as well as signs of myocardial ischemia (ST segment depression) during maximal exercise.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Investigations into the origin of the high pressure neurological syndrome: the interaction between pressure, strychnine and 1,2-propandiols in the mouse.
1. The effects of a variety of structural isomers of the centrally acting muscle relaxant mephenesin on the high pressure neurological syndrome have been investigated. Threshold pressures for the onset of the behavioural signs, tremors and convulsions, were established. The effects of these compounds on the response to pressure were also compared with their ability to antagonize the convulsive action of strychnine. 2. The dose-response relationships for strychnine and picrotoxin were investigated at fixed pressures. Additionally, the dose-response relationship of strychnine, in the presence of mephenesin, at pressure was investigated. 3. All the isomers of mephenesin protected against the effects of both pressure and strychnine. The relative potency was found to be identical with respect to both. Mephenesin was clearly the most effective; it raised the threshold pressure for tremors by 2.5 times, that for convulsions elicited by pressure by 1.5 and the ED50 for strychnine convulsions by 1.6 times. Strychnine was found to be strictly additive with pressure whereas picrotoxin exhibited gross deviations from additivity. Mephenesin ameliorated the combined effects of pressure and strychnine equally. 4. The marked dependence on structure of the anticonvulsant activity of the mephenesin isomers can be interpreted as evidence that pressure acts not by some general perturbation of the membranes of excitable cells but rather via some specific interaction. The finding that strychnine and pressure are strictly additive supports the idea of specificity and also indicates that they may share a common mechanism in the production of convulsions. By analogy with the established mechanism of action of strychnine, it is suggested that the hyperexcitability associated with pressure might arise from an action on glycine-mediated inhibitory processes.
Animals↗
Effect of benzazole-related centrally acting muscle relaxants on HPNS.
A series of benzazole-related, centrally acting muscle relaxants, comprising benzimidazole, chlorzoxazone, and zoxazolamine, were found to give substantial protection against the tremors and convulsions associated with the high pressure neurologic syndrome (HPNS) in the mouse. In this respect they represent a new class of nonanesthetic, anti-HPNS agents. Their anti-HPNS properties, like those previously established for the mephenesin group of centrally acting muscle relaxants, seem to be related to their ability to antagonize the convulsive action of strychnine. These findings are consistent with the suggestion that one of the principal effects of pressure, expressed as HPNS, arises from a perturbation of strychnine-sensitive mechanisms.
Animals↗
Histologic analysis of costochondral and sternoclavicular grafts in the TMJ of the juvenile monkey.
Variability in growth response of the mandible after replacement of the mandibular condyle with the costochondral junction of a rib (CCJ) is common. Other donor graft sites that are more similar to the mandibular condyle might be more suitable for mandibular condylar replacement. Previous studies have shown the histomorphologic and developmental similarities between the sternoclavicular joint (SCJ) and temporomandibular joint (TMJ). The purpose of this study was to evaluate histologically short-term adaptations within the TMJ after replacement of the mandibular condyle with the autogenous sternal head of the clavicle, and to compare these adaptations with autogenous CCJ and mandibular condyle (surgical control) transplants. Bilateral vertical ramus osteotomies were performed in 12 juvenile Macaca mulatta with the left condyle being immediately replaced and the right condyle removed and replaced with either the sternal head of the clavicle or costochondral junction of a rib. All grafts were stabilized with maxillomandibular fixation for five weeks. Two animals in each group were killed at five, 11, and 17 weeks postsurgery and prepared for histologic analysis. The results indicate that: 1) incorporation of all grafts into the recipient site occurred and all animals had good mandibular function and occlusion throughout the follow-up period; 2) the clavicular and mandibular condylar grafts were incorporated sooner than the CCJ grafts; 3) clavicular graft changes resembled those of the condylar grafts histologically while the costal grafts remained inert and unchanged; and 4) a new condylar process with cartilage similar to that of a normal mandibular condyle regenerated in the costal graft animals from cells presumably contributed by the periosteum of the mandibular ramus and TMJ capsule.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Ultrasonically induced gas bubble production in agar based gels: Part I. Experimental investigation.
Macroscopically visible gas bubbles can be produced in an agar based gel by irradiation with either continuous or pulsed ultrasound at frequencies from 0.75 to 3.0 MHz. The variation in the number of bubbles formed with frequency, acoustic pressure, pulse length, duty cycle, and temperature closely resembles that seen in vivo. Furthermore, the acoustic pressure required to initiate bubble formation is also close to that required in vivo. It has been observed that alterations in the concentration and pH of the gels can have a profound effect on the nature and quantity of bubbles. This suggests that not only is this gel model suitable for the representation of the macroscopic features of bubble formation in vivo, but can be used to gain information about the preexisting bubble nuclei. Based on the experimental results obtained it can be suggested that for peak negative acoustic pressures of up 1 MPa (equivalent, for a plane travelling sinusoidal wave, to a time averaged intensity of 30 W/cm2) bubble formation can be avoided by the use of high frequencies, short pulse lengths and long duty cycles.
Agar↗
Ultrasonically induced gas bubble production in agar based gels: Part II. Theoretical analysis.
Visible size gas bubbles can be produced in an agar based gel when irradiated with either continuous wave (CW) or pulsed ultrasound. It is shown that many aspects of the production of these bubbles can be explained in a qualitative manner by a theoretical model based upon growth of a cavitation nucleus by rectified diffusion. Quantitative predictions for the number of bubbles produced as a function of various parameters tend to be different from measured values by less than an order of magnitude. The results given here provide a useful theoretical basis for the explanation of earlier measurements of ultrasonically induced bubbles in vivo.
Agar↗
Spectrum of congenital heart disease in CHARGE association.
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Abnormalities, Multiple↗
Punitive damages: the real story.
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Data Collection↗
Relationship of employment status to mental health and family variables in black men from single-parent families.
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Adult↗
Ultrasonic monitoring of decompression procedures.
p6rly detection of bubbles may provide clues to the mechanism of their formation, and a knowledge of their extent during a decompression may allow the prevention of decompression sickness. We have used ultrasound imaging to study bubble formation in peripheral tissues. The results suggest that: (a) a threshold supersaturation for bubble formation exists; (b) the earliest bubbles are intravascular; (c) before signs of decompression sickness a substantial accumulation of stationary bubbles occurs. Despite the success of Doppler methods in detecting moving bubbles after decompressions normally considered safe, recent studies have shown that the correlation between number of bubbles detected and symptoms of decompression sickness is often poor. We have used a time integral of the ultrasound images, which avoids laborious image analysis, to follow the extent of both moving and stationary bubbles. Human trials involving a wide variety of decompressions suggest that correct prediction of symptoms is possible.
Animals↗
Correlation between changes in R wave amplitude and left ventricular volume induced by rapid atrial pacing.
To examine the Brody effect in humans, we studied 15 patients by means of coronary sinus pacing. We measured left ventricular (LV) volumes from the cardiac output (measured by the thermodilution technique) and LV ejection fraction (measured by radionuclide ventriculography). Pulmonary blood volume was determined by means of cardiac output and mean pulmonary transit time. In six patients, pacing was performed at two different rates, resulting in 21 pacing measurements. The heart rate increased with pacing from 73 +/- 11 to 119 +/- 19 bpm (mean +/- standard deviation, p less than 0.001). The end-diastolic volume (EDV) and the end-systolic volume (ESV) decreased with pacing (p less than 0.001 each). The R wave amplitude decreased with pacing (1.44 +/- 0.63 mV control vs 1.32 +/- 0.58 mV with pacing; p less than 0.01). R wave amplitude decreased in 19 of the 21 pacing studies (90%); EDV and ESV decreased in all 21 pacing studies, and pulmonary blood volume decreased in 14 of the 15 pacing studies (93%) performed in 11 patients. There was a significant correlation between the percentage of change in R wave amplitude with the percentage of change in EDV (r = 0.54, p less than 0.01) and with the percentage of change in ESV (r = 0.54, p less than 0.01). These results, therefore, validate Brody's hypothesis and indicate that changes in LV volumes affect the R wave amplitude.
Adult↗