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Biomedical subjects

M Bowers

Publications and source records attributed to M Bowers.

At least 55 records · Page 3Linked to original sources
PubMed1995

Herpesviruses.

Explore the source record for details and available documents.

2-Aminopurine↗
PubMed1993

Acute electrical stimulation increases extramyocardial collateral blood flow after a cardiomyoplasty.

We hypothesized that acute electrical stimulation of a latissimus dorsi cardiomyoplasty would augment the collateral blood flow delivered by the skeletal muscle to the heart. This hypothesis was tested in an animal model (13 goats) of coronary artery disease. Six weeks after a cardiomyoplasty was performed, myocardial collateral blood flow derived from the latissimus dorsi muscle was measured with colored microspheres when the muscle was at rest and during electrical stimulation of the thoracodorsal nerve at 1.25 Hz. The area at risk for ischemia averaged 13.37 +/- 2.08 g (mean +/- standard error), or 18.4% of left ventricular mass (n = 13). At rest, significant skeletal muscle-derived collaterals developed in 9 animals, and formed predominantly to chronic ischemic myocardium (mean +/- standard error, 0.07 +/- 0.02 mL.g-1 x min-1; n = 9), rather than infarct (0.03 +/- 0.02 mL.g-1 x min-1; n = 5), or normal myocardium (0.0005 +/- 0.0001 mL.g-1 x min-1; n = 9). Stimulation increased skeletal muscle-derived collateral blood flow to chronic ischemic areas to 0.38 +/- 0.09 mL.g-1 x min-1 (n = 9) (p < 0.05). During stimulation, the collateral flow was greater in the epicardium (0.46 +/- 0.11 mL.g-1 x min-1) than in endocardium (0.14 +/- 0.09 mL.g-1.min-1) (p < 0.05). This study demonstrates that electrical stimulation of a latissimus dorsi cardiomyoplasty increases extramyocardial collateral blood flow to chronic ischemic myocardium.

Animals↗
PubMed1991

Preparation and characterization of N-(1-pyrenyl)iodoacetamide-labeled Escherichia coli RNA polymerase.

N-(1-Pyrenyl)iodoacetamide has been used to introduce fluorescent probes into Escherichia coli RNA polymerase. After an incubation time of 15 min, approximately 2 pyrene equiv was introduced per enzyme molecule. There was no further increase in modification after more extended periods of incubation. Neither calf thymus DNA nor nucleotides protected the holoenzyme from modification. Thus, the sites of modification do not appear to involve the binding sites for polynucleotides or the ribonucleoside triphosphates. From the isolation and analysis of the individual subunits, it was found that sigma contained approximately 1 pyrene equiv, beta contained 0.6, beta' contained 0.6, and alpha less than 0.1. Spectral and Stern-Volmer analyses indicate that the covalently attached pyrene molecules are in comparable apolar microenvironments. On the basis of CD analyses, the introduction of pyrene molecules into RNA polymerase alters its secondary structure. This alteration in secondary structure manifests itself by a reduction in overall enzymatic activity. Transcript analysis of the products obtained by using a linearized plasmid containing the A1 promoter and the Te terminator of bacteriophage T7 indicates that the pyrenyl derivative is capable of producing full-length transcripts and that it has an efficiency of chain termination comparable to the native enzyme. Analysis of tau plots for the interaction of the pyrenyl derivative and the native enzyme, respectively, with the A1 promoter yielded comparable values for the isomerization constant in the conversion of the closed complex to an open one. Comparable values were also obtained for the association constant. The rate of chain elongation for the pyrenyl derivative, however, is approximately 54% of that observed for the native enzyme. Thus, the decrease in overall transcriptional activity observed with the pyrenyl derivative is not due to a decrease in the efficiency of initiation or premature termination, but rather to a decrease in the rate of chain elongation.

Circular Dichroism↗
PubMed1990

Adjunct executive appointment for faculty. An innovation in nursing collaboration.

The need for collaboration has never been greater. The healthcare delivery system faces unprecedented challenges arising from prospective payment, competition in the marketplace, higher patient acuity levels, and a shortage of professional nursing staff. The authors discuss a service-education collaboration model based on adjunct executive appointments of faculty members to healthcare organizations. The authors describe the model, a conceptual framework to guide its development, case studies of its implementation, and a summary of the benefits and risks associated with the initial implementation of the model.

Hospitals, Community↗
PubMed1987

Distributions of the activities of aspartate aminotransferase isoenzymes in rat retinal layers.

Distributions of the activities of the cytosolic (cAAT) and mitochondrial (mAAT) isoenzymes of aspartate aminotransferase were determined in rat retinal layers. cAAT was highest in the photoreceptor inner segments, inner nuclear layer and inner plexiform layer; mAAT was highest in the inner segments. The high activity in the inner segments indicates that both isoenzymes are involved in energy metabolism in addition to a possible role in neurotransmission.

Animals↗
PubMed1987

Distribution of glutaminase activity in retinal layers of rat and guinea pig.

The glutaminase activity in rat and guinea pig retina is twice as high in photoreceptor inner segments as in any other layer. Since the inner segments are involved in non-transmitter-related metabolic functions, it is suggested that glutaminase should not necessarily be taken to imply glutamatergic neurotransmission until the function of the high activity in regions such as the inner segments is better understood.

Animals↗
PubMed1984

Aspartate aminotransferase activity in fiber tracts of the rat brain.

Activity of aspartate aminotransferase, an enzyme which catalyzes the interconversion of the excitatory transmitter candidates, glutamate and aspartate, has been measured in fiber tracts of rat, with an emphasis on sensory and motor systems of the brain. Most tracts had significantly higher activities than the cholinergic facial nerve root, consistent with the possibility that a component of aspartate aminotransferase activity might serve as a marker for neurons using glutamate and/or aspartate as neurotransmitter. Highest activity was in the auditory nerve root. On the other hand, a close correlation was found between aspartate aminotransferase and malate dehydrogenase activities in the fiber tracts, raising the question whether aspartate aminotransferase activity may be more closely related to energy metabolism than to transmitter metabolism.

Animals↗
PubMed1975

Antibiotic treatment of secretory otitis media assessed by impedence audiometry.

Impedence audiometry was used to assess the response to treatment with antibiotics of children with secretory otitis media. Only ears with pressure at maximum compliance of less than --150mm water were included. There was a significant improvement with Bactrim, ampicillin and Vibramycin. There was no change without treatment and deterioration with penicillin.

Ampicillin↗