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S Schaeffer

Publications and source records attributed to S Schaeffer.

28 records · Page 2Linked to original sources
PubMed1996

Presence of renin within intramitochondrial dense bodies of the rat adrenal cortex.

It has been suggested that tissue-specific expression of the genes of the renin-angiotensin system (RAS) leads to local generation of angiotensin (ANG) II with specific physiological implications. We demonstrate here that an intracellular RAS exists in adrenal glomerulosa cells; 60 h after bilateral nephrectomy and hemodialysis, renin and prorenin were eliminated from the circulation, whereas intra-adrenal renin content increased (control rats: 2 +/- 0.5 ng ANG I.mg-1.h-1; anephric rats: 25 +/- 2). Thus renin is produced locally within adrenal cells. We obtained immunocytochemical and biochemical evidence for the presence of renin within intramitochondrial dense bodies of the zona glomerulosa. After nephrectomy, dense bodies increased in number, size, and renin content (control rats: 2.5 +/- 0.7 ngANGI.mg-1.h-1; anephric rats: 43 +/- 7). Angiotensin-converting enzyme (ACE) was also present within mitochondria and their dense bodies. In addition, in adrenal cortex of anephric rats, giant dense bodies were observed, which contain renin and strongly react with an anti-angiotensinogen antibody. The localization of renin, ACE, and angiotensinogen at these sites provides new evidence for the existence of an intracellular adrenal RAS.

Adrenal Cortex↗
PubMed1994

911 and emergency department use for chest pain: results of a media campaign.

STUDY OBJECTIVE: We evaluated the effects of a community public education campaign that encouraged patients to quickly call 911 after the onset of acute myocardial infarction (AMI) symptoms. SETTING AND PARTICIPANTS: The media campaign focused on residents 50 years of age or older in King County, Washington, which has a population of 1.5 million (1990 census). DESIGN: We determined 911 responses for chest pain, emergency department visits for AMI symptoms, the number of patients admitted to a CCU with an admitting diagnosis of rule-out MI, and the number of confirmed AMIs before and after the campaign. RESULTS: The number of emergency medical services (EMS) responses (911 runs) for patients 50 years of age or older experiencing AMI symptoms increased significantly during the media campaign. ED visits for chest pain also increased significantly during the campaign, as did the number of patients 50 years of age or older admitted to a King County CCU with an admitting diagnosis of rule-out MI. Each of the above increases tapered--with time after the media campaign but remained above baseline. CONCLUSION: An intense public education campaign can significantly increase EMS use, ED visits, and CCU admissions for AMI symptoms. However, these effects taper off with time after the campaign.

Aged↗
PubMed1989

A community survey of the potential use of thrombolytic agents for acute myocardial infarction.

We surveyed all patients admitted to nine community hospital coronary care units to determine what proportion could be candidates for thrombolytic therapy. During the 12-month study period, there were 4,115 admissions for possible acute myocardial infarction, and 1,076 (26%) had a discharge diagnosis of myocardial infarction. Patients with myocardial infarction had the following characteristics: 60% had ST elevation seen on the first ECG, 17% had ST depression without ST elevation, 75% were less than 75 years old, 75% had no contraindications to thrombolytic therapy, 78% arrived at hospital within six hours of onset of symptoms, and 94% arrived within 24 hours of symptoms. Criteria for administration of thrombolytic therapy can be grouped as restrictive (arrival within six hours of symptoms and ST elevation) or liberal (arrival within 24 hours of symptoms and ST elevation or ST depression). Applying these characteristics, 26% met restrictive criteria for treatment with thrombolytic therapy, and 36% met liberal criteria. Until liberal criteria (therapy up to 24 hours and ST depression) are convincingly shown to be of benefit, we believe clinicians should apply restrictive criteria to potential candidates for thrombolytic therapy.

Aged↗
PubMed1988

A new rhythm library for testing automatic external defibrillators: performance of three devices.

A library of arrhythmias obtained from patients with cardiac arrest was developed. Such a data base will permit both in vitro testing of the rhythm analysis system of automatic external defibrillators before clinical field trials are conducted and comparison of devices. Defibrillators equipped with voice/electrocardiographic tape recorders and used in the prehospital defibrillation programs in Iowa and King County, Washington provided the rhythm source. From these recordings, segments of ventricular fibrillation with minimal artifact and a duration of greater than or equal to 6 s were selected. Segments of ventricular fibrillation (n = 102) were categorized by average peak amplitude as fine (1 to less than 3 mm), medium (3 to less than 7 mm), coarse (7 to less than 12 mm) and extra coarse (greater than or equal to 12 mm), and transcribed onto high fidelity videocassette tapes. Nonventricular fibrillation cardiac arrest rhythms (n = 144), which included wide complex idioventricular rhythms, ventricular and supraventricular tachycardias, asystole and artifact, were also transcribed. Automatic external defibrillators developed by three manufacturers reached a treat (shock) decision on 88 to 93% of the ventricular fibrillation rhythms and on 5 to 10% of the nonventricular fibrillation rhythms. The latter decisions were defined as false positive, though for many rapid nonventricular fibrillation rhythms, countershock may be the appropriate treatment response. There were no statistically significant differences among the three devices in the shock/no shock decisions. A variety of ventricular fibrillation arrhythmias and terminology to express the preclinical performance of automatic external defibrillators are defined. Three commercially available automatic external defibrillators appear to successfully identify ventricular fibrillation and nonventricular fibrillation rhythms.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1987

The structural basis of the inner blood-retina barrier in the eye of Macaca mulatta.

This is a morphological analysis of the inner blood-retina barrier in various segments of the retinal vasculature in the eye of Macaque monkeys. The primary aims of this study are to identify the components of the walls of the arteries, central capillaries, peripheral capillaries and veins of the retina using light and electron microscopy, and to compare and contrast junctional morphology as revealed by thin section electron microscopy and freeze-fracture. The walls of these vascular segments are composed of continuous endothelium, muscle cells or pericytes, and connective tissue. Endothelial cells are joined by tight and gap junctions. In freeze-fracture replicas, tight junctions consist of a continuous, complex network of branching and anastomosing strands which do not possess free endings. The intramembrane strands of tight junction remain preferentially associated with the outer membrane leaflet or E-face of the endothelial plasma membrane and sit at the bottom of linear strands or grooves. However, particles and fragments of the intramembrane strands may be avulsed from the E-face during the fracture process and are associated with ridges on the inner membrane leaflet or P-face. The total number of plasmalemmal vesicles per unit area of endothelial cell for each vascular segment in thin sections is less than non-barrier endothelium, but greater than barrier endothelium. The paucity of plasmalemmal vesicles and the complexity of the tight junctional network contribute to the barrier function of the retinal vascular endothelium.

Animals↗
PubMed1984

Endogenous surface phosphorylation reactions and ectokinase activity in the guinea pig T lymphocyte.

The guinea pig T lymphocyte, known to interact with other cells via direct cell-to-cell contact, exhibits endogenous surface kinase activity as reflected by the appearance of four major labeled bands in autoradiographs of dried sodium dodecyl sulfate (NaDoSO4)-polyacrylamide gel electrophoresis gels when intact cells are briefly exposed to micromolar concentrations of [gamma-32P]ATP followed immediately by solubilization with NaDoSO4 to terminate the reaction. This pattern differs from the labeling of intracellular components which is seen when intact cells are incubated with 32PO4 to generate intracellular [gamma-32P]ATP when only two major labeled bands of protein with different molecular weights are seen. Of a number of modulators of lymphocyte function tested, cyclic GMP and phytohemagglutinin (PHA) caused additional bands to appear in cells exposed to [gamma-32P]ATP. The labeling of added casein was catalyzed by intact cells harvested 4 weeks after injection of animals with Freund's complete adjuvant but not earlier. These findings indicate that plasma membrane kinase activity of guinea pig T lymphocytes is accessible to the extracellular environs (ectokinase activity) and to endogenous surface substrates and that the limitation for such reactions is the availability of ATP in the extracellular component. In view of the number of circumstances under which ATP could appear outside of cells for brief periods of time, these reactions could well take place in vivo.

Animals↗
PubMed1984

Development and implementation of emergency CPR instruction via telephone.

We developed a cardiopulmonary resuscitation (CPR) message that can be given via telephone by emergency dispatchers directly to an individual reporting a cardiac arrest. The message was developed and evaluated on the basis of empirical observation of CPR performance of 203 community volunteers during simulated cardiac arrest events. The majority of volunteers were women, aged 30 to 80 years, who had not had previous CPR training. An average of five ventilation and compression cycles were given within five minutes using telephone instruction. We judged the quality of CPR to be comparable to the performance of individuals who have received formal training. The specific words used in the message directly determined adequacy of performance, and resulted in significantly better CPR performance than did impromptu instruction offered by professional dispatchers (P less than or equal to .02).

Adult↗
PubMed1965

Adhesive fillings.

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Dental Materials↗