Search PubMed⌕ Search

Biomedical subjects

R Davis

Publications and source records attributed to R Davis.

At least 397 records · Page 22Linked to original sources
PubMed1984

Electron microscope localization of acetylcholinesterase and butyrylcholinesterase in the ciliary ganglion of the cat.

Ciliary ganglia (CG) of cats were stained for acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by the bis-(thioacetoxy) aurate (I), or Au(TA)2, method for examination by electron microscopy. Acetylcholinesterase was localized along the axolemmas of the preganglionic fibers and their terminals and on the plasmalemmas of the perikarya and dendrites of the ganglion cells, as in the cat superior cervical ganglion (SCG). In contrast to the SCG, AChE was also found in significant amounts in the rough endoplasmic reticulum of the CG cells and dendrites, and in varying but high concentrations in channels of extracellular space in the complex capsular region surrounding the perikarya and dendrites. Butyrylcholinesterase was confined chiefly to the dendritic and perikaryonal plasma membranes of the ganglion cells, as in the SCG. Lysosomes and mitochondria were stained chiefly for non-cholinesterase enzymes, as indicated by the physostigmine-treated controls. The significance of these distributions is discussed.

Acetylcholinesterase↗
PubMed1984

School health education research: future issues and challenges.

This paper presents the view that the dissemination of effective school health education constitutes a significant problem that deserves high priority on a national research agenda for school health education. Justification of dissemination is grounded in two presuppositions: (1) that there is a positive correlation between health education and the practice of health-enhancing behaviors and (2) that health education is an appropriate and fundamental task for schools. Two complex sub-problems are discussed. The first is related to the fact that there are no data to help us determine how many children in this country actually receive health information in schools. In addition, there is insufficient evidence to ascertain either the quality or quantity of health information children receive or where in the curriculum the presentation of that information occurs. The second problem pertains to the myriad of complex factors that impede the implementation of health education in schools. These two problems are re-cast into a series of researchable questions.

Adolescent↗
PubMed1983

Structural gene coding for multifunctional protein carrying orotate phosphoribosyltransferase and OMP decarboxylase activity is located on long arm of human chromosome 3.

In humans, deficiency in the last two enzymes of UMP biosynthesis, orotate phosphoribosyltransferase (OPRT) and OMP decarboxylase results in the inborn error of metabolism hereditary orotic aciduria, type 1. In this manuscript, we present immunologic, molecular, biochemical, and genetic evidence that the gene coding for this set of enzymatic activities is located on the long arm of human chromosome 3. The evidence presented here is consistent with both these activities being carried on the same multifunctional protein in mammalian cells. These studies allow further genetic analysis of human chromosome 3, confirming that human markers ACY-1, previously assigned to 3p21, and beta-gal, previously assigned by others to the region 3(p21-q21), must be in the region 3 (cen-p21) and confirming the regional assignment of a human DNA segment, D3S1, to 3q12. The significance of these studies to genetic analysis of genes on human chromosome 3, some of which appear to play a role in some forms of malignancy, is discussed.

Carboxy-Lyases↗
PubMed1983

Fast neutron irradiation of metastatic cervical adenopathy: the results of a randomized RTOG study.

Between 1977 and 1982, 199 evaluable patients with measurable cervical adenopathy were entered on a prospective, randomized RTOG study evaluating the use of fast neutrons in treatment of advanced, inoperable squamous cell carcinomas of the head and neck region. One hundred-eleven patients were randomized to receive mixed beam radiation therapy, and 88 were randomized to the photon control treatment. The complete response rates were 86% for mixed beam vs 75% for photons for Stage N1 nodes, 62% for mixed beam vs 48% for photons for Stage N2 nodes, and 63% for mixed beam vs 53% for photons for N3 nodes. The percents of patients remaining free of their adenopathy for two years were 78% for mixed beam vs 55% for photons for Stage N1 nodes, 39% for both mixed beam and photons for N2 nodes and 24% for mixed beam vs 13% for photons for N3 nodes. The median disease-free status was 20.3 months for mixed beam treated patients and 6.4 months for photon-treated patients. Patients who had clearance of cervical adenopathy survived significantly longer than those who did not.

Carcinoma, Squamous Cell↗
PubMed1983

Reduction of intractable seizures using cerebellar stimulation.

Of the 32 patients with active intractable seizures, 27 had spastic cerebral palsy (CP) and 5 had epilepsy (EP), and all underwent chronic cerebellar stimulation (CCS) (amplitude 1-2 microC/cm2/phase, rate 10-180 pps, duration of implantation 0.5-7 years, average 4.5 years). Grand mal seizures occurred in 23 patients (19 CP, 4 EP); with CCS 17 patients stopped, 4 had a reduction, 3 were unchanged. Petit mal occurred in 9 patients (8 CP, 1 EP); with CCS 4 patients ceased seizuring, 3 reduced and 2 were unchanged. Myoclonic seizures were present in 6 patients (5 CP, 1 EP); with CCS 1 patient stopped, 3 had a reduction while 2 patients were unaffected. Severe psychomotor seizuring affected 2 EP patients, 1 had a marked behavioral improvement and finally stopped seizuring for the past 9 months. Overall, CCS stopped 18 (57%) of the patients seizuring, reduced a further 9 (28%), with no effect in 5 patients (15%).

Adolescent↗
PubMed1983

Fast neutron radiation therapy for glioblastoma multiforme. Results of an RTOG study.

Between January 1977 and September 1980, 166 patients were entered on a RTOG protocol comparing neutron-boost radiotherapy with standard treatment for patients with glioblastomas. Eighty-three patients were randomized to receive a neutron boost and 83 to receive a photon boost after 50 Gy photon, whole-brain irradiation. Of these, six were ineligible and two were cancelled, leaving 158 patients available for analysis. The median survival for the neutron-boost group was 9.8 months, compared to 8.6 months for the photon-boost group. The difference is not statistically significant. Autopsies revealed actively growing persistent tumor in all photon-treated patients compared to no evidence of actively growing tumor in the majority of neutron-treated patients.

Brain Neoplasms↗
PubMed1982

Measles in the tropics and public health practice.

Measles shows three distinct transmission patterns in the tropics, one each in urban, rural and insular or very remote areas. The characteristics of measles transmission are reviewed for each area, both with and without immunization. Planning must be based on the best use of currently underused infrastructure in the light of epidemiology. Mass mobile campaigns are not advised for urban areas. Vaccination of the sick and the well as part of episodic medical care is proposed, and vaccination of the sick is supported as safe and effective. Age floors and ceilings should be set with reference to the local situation; adoption of international "rules of thumb", without reference to local conditions, is inadvisable." A mixed strategy is urged for rural areas, with routine immunization against measles as part of a multi-antigen programme. Routine immunization should be complemented by annual surveillance and containment during the seasonal trough. Research and development needs in measles control include better understanding of measles epidemiology, more operationally useful quantitative models, and trials of new control strategies. Control, elimination and eradication are defined and discussed.

Adolescent↗
PubMed1982

Mutants of plasmid prophage P1 and elevated copy number: isolation and characterization.

A series of mutations of the P1 plasmid prophage that lead to increased copy number was isolated and analyzed. The copy number of the mutants was elevated at least five- to eightfold relative to wild-type P1, as determined by single-cell resistance to antibiotics, activity of enzymes, content of superhelical DNA, and reassociation kinetics. The copy number of two of the mutants was temperature dependent. Based on dominance tests, the mutants fell into two classes, cis specific and recessive. The latter class included a temperature-sensitive copy mutant. The existence of a class of recessive mutants suggests that the replication of the P1 plasmid is negatively regulated.

Ampicillin↗
PubMed1982

Management of chronic peritoneal catheter malfunction.

This paper presents a modification of Tenckhoff's insertion procedure for chronic peritoneal dialysis catheters and reviews the results of a technique of management of catheter malfunction by manipulation which obviates the need for catheter replacement. 43 catheters in 33 patients were observed for no less than 1 year. Catheters which malfunctioned within 3 weeks benefited only marginally from manipulation. In those catheters which functioned for more than 3 weeks, manipulation extended mean survival time by 103% (8.5-17.3 months) and overall survival did not differ statistically from catheters not requiring manipulation. The technique is safe and simple and contributes to the effective management of patients undergoing chronic peritoneal dialysis.

Adult↗
PubMed1982

Management of infected cerebellar stimulation systems.

Over a 7-year period (February 1974 through February 1981), 318 patients underwent the implantation of cerebellar stimulation systems for the reduction of spasticity (98%) or epilepsy (2%). A total of 518 procedures were carried out to implant and maintain the equipment during this period. Fourteen patients developed infections in the tissue around their implanted systems, which represented 4.4% of the patients or 2.7% of the procedures performed. Staphylococcus aureus was the infectious agent in 7 cases (50%), the clinical features of which occurred usually within 1 month. Staphylococcus epidermidis infected 5 patients with features presenting late (more than 2 years) after the initial implantation. The management involved antibiotic therapy for 2 weeks in all 14 patients. In 12 patients, the entire system was removed, with 100% eradication of the infection. In the other 2 patients, the radio receiver and lead wires up to but not including the cerebellar electrode pads were removed. One of these 2 patients has been free of infection for 4 years. The other had S. aureus cultured from removed electrode pads after 6 weeks. Of the 14 cases, morbidity was severe in only 1 patient. Seven patients underwent reimplantation 6 weeks after the infection.

Ampicillin↗
PubMed1981

Electron microscope localization of acetylcholinesterase and butyrylcholinesterase in the superior cervical ganglion of the cat. II. Preganglionically denervated ganglion.

Cat superior cervical ganglia (SCG), denervated preganglionically 6-8 d previously, were stained for acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by the bis-(thioacetoxy)aurate (I), or Au(TA)2, method and compared by electron microscopy with normal SCG described previously (Davis, R., and G. B. Koelle. 1978. J. Cell Biol. 78:785-809). In confirmation of earlier light microscopic findings by the highly specific copper thiocholine method, there was nearly a total disappearance of AChE from the ganglion; no myelinated or unmyelinated axons with AChE-stained axolemmas were found, and only occasional traces of AChE staining were noted at dendritic and perikaryonal plasma membranes. Considerable staining for BuChE persisted at the latter sites, however. As in the normal SCG, physostigmine-resistant staining, caused by noncholinesterase enzymes plus the possible presence of very low concentrations of AChE or BuChE, was noted at external mitochondrial membranes, elements of the endoplasmic reticulum of neurites and Schwann cells, and also in lysosomes. These findings confirm the previous identification of AChE-stained myelinated fibers in the normal SCG as preganglionic and of the unstained myelinated fibers as postganglionic. It is proposed that the maintenance of AChE at postsynaptic sites in normal ganglia is caused by the release of a trophic factor(s) from presynaptic terminals. The source of the postsynaptic BuChE, which is apparently completely absent from the endoplasmic reticulum of the ganglion cells, remains unexplained.

Acetylcholinesterase↗
PubMed1981

Beneficial augmentation following dorsal column stimulation in some neurological diseases.

101 patients with multiple sclerosis and other demyelinating diseases have undergone dorsal column stimulation (DCS) during the past 6 years. DCS augmented weakened neurological functions in 94 patients. Varying improvements were seen in general strength, balance and gait, sensory modalities speech, and bladder function with an important increase in endurance. Two different DCS systems were implanted: 65 patients had a radio frequency stimulator and 36 had a totally implantable programmable stimulator. Except for the first 4 patients, who underwent an initial trial of DCS, permanent implantation of the stimulation system was done as the initial procedure in the series. 16 patients died of their disease or other causes unrelated to the stimulator. DCS is a safe and efficacious method for augmenting the neurological function in most selected patients and can lead to an improved quality of life.

Adolescent↗