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Biomedical subjects

R Powers

Publications and source records attributed to R Powers.

71 records · Page 4Linked to original sources
PubMed1989

Use of maxillary miniplates and screw system in the treatment of hand fractures: a preliminary report.

The vast majority of hand fractures can be adequately treated with techniques such as closed reduction and external splinting or with a variety of internal fixation devices. Choice of stabilization methods depends on individual surgical preference, fracture location, and the geometry of the bony injury. Fracture stabilization that allows early mobilization is advantageous in achieving rapid bone healing and restoration of function by minimizing joint and tendon complications. Rigid internal fixation with miniplates and screws permits stabilization and compression of fracture segments, thereby permitting early bone loading and motion. Although the role of rigid internal fixation with miniplates and screws in hand fractures is well documented in the literature, in this article we present our preliminary experience with Howmedica's (Rutherford, NJ) Luhr vitallium miniplate and screw system in treating hand injuries.

Adult↗
PubMed1979

The incidence of osteo-arthritis of the temporomandibular joint in various cultures.

Three hundred and forty-eight cranial remains from Bronze and Iron Age British, Romano-British, Anglo-Saxon, Eastern Coast Australian aborigines, Medieval Christian Norse, Medieval Scarborough, 17--20th century British and German cultures, were examined for the presence of osteoarthritis in the temporomandibular joints. Cultures exposed to more stringent living conditions and with well-worn teeth had about twice the incidence of osteo-arthritis as the more sophisticated cultures. In general, loss of either molar support or occlusal imbalance were potent aetiological factors in this disease.

Adolescent↗
PubMed1977

Comparative study of immunologic methods for demonstration of antibodies to soluble nuclear antigens. Immunofluorescence, hemagglutination, complement fixation, and immunodiffusion.

Four methods to detect antibodies reactive with soluble nuclear antigens were compared-the fluorescent antibody technique, hemagglutination, complement fixation, and immunodiffusion. Centain advantages and disadvantages of each method are described. The first three methods have greater sensitivity than immunodiffusion, but immunodiffusion discriminates most reliably between different antibodies.

Antibodies, Antinuclear↗
PubMed1977

A soluble acidic protein of the cell nucleus which reacts with serum from patients with systemic lupus erythermatosus and Sjögren's syndrome.

A soluble nuclear antigen that reacts with sera obtained from patients with systemic lupus erythematosus and Sjögren's syndrome has been described. The antigen, tentatively named the Ha antigen after the prototype serum, was shown to react with specific antibodies by precipitin, complement fixation, and immunofluorescence techniques. The Ha antigen prepared from isolated nuclei of calf thymus glands, calf liver, and rat liver showed identical immunological reactivities; a wide distribution among different species and tissues is presumed. The Ha antigen was destroyed by trypsin and relatively mild heat or pH variation from neutrality, but was resistant to DNase or RNase. Many of these characteristics are similar to those of the "B" antigen to which antibodies have recently been described in Sjögren's syndrome. The nuclear origin of the Ha antigen was confirmed by the speckled nuclear immunofluorescence staining pattern given by purified antibody to Ha obtained from a specific immune precipitate. Preliminary results showed approximately 13% of patients with systemic lupus erythematosus and 30% of patients with Sjögren's syndrome had precipitating antibodies to the Ha antigen.

Antigen-Antibody Reactions↗
PubMedDate not supplied

Impaired phosphoinositide hydrolysis in Alzheimer's disease brain.

The effect of Alzheimer's disease (AD) on the activity of the phosphoinositide second messenger system was studied by measuring the hydrolysis of [3H]phosphatidylinositol (PI) by membranes from postmortem human prefrontal cortex. The activity of phospholipase C was similar in AD and control tissue. Activation with GTP gamma S and with carbachol demonstrated less [3H]PI hydrolysis in AD than control membranes. The concentration of Gq/11, the G-proteins most likely functional in phosphoinositide metabolism, was unchanged in AD compared with controls, indicating that function of the receptor-G-protein complex rather than the G-protein concentration was the site of the impairment in AD. These results indicate that postsynaptic muscarinic receptor responses are impaired in AD, a finding that may explain, in part, the limited therapeutic responses achieved by administration of cholinomimetics to patients with AD. Also, this assay provides a means to identify cholinomimetics that are most effective in activating muscarinic receptor-coupled phosphoinositide hydrolysis in human brain, agents which should have the greatest potential for providing therapeutic responses in AD.

Aged↗
PubMedDate not supplied

Effects of postmortem interval, age, and Alzheimer's disease on G-proteins in human brain.

Heterotrimeric G-proteins are critical components in many receptor-coupled signal transduction systems, and altered levels and functions of G-proteins have been implicated in several neurological disorders, including Alzheimer's disease. Investigations in postmortem human brain provide a direct approach to study G-protein involvement in neurological disorders. Therefore, the effects of postmortem interval, aging, and Alzheimer's disease on G-protein levels were determined in postmortem human brain and an assay to measure activation of G-proteins was developed. Within the postmortem interval range of 5 to 21 h, the levels of G alpha i1, G alpha i2, G alpha s, and G beta were stable, whereas G alpha q and G alpha o decreased slightly, in human prefrontal cortex. In subjects aged 19 to 100 y, decreased levels of G alpha q and G alpha o were significantly correlated with increased age, but levels of the other G-protein subunits did not vary. In Alzheimer's disease prefrontal cortex, superior temporal gyrus, and occipital cortex, all G-protein subunit levels were equivalent to those in matched controls except for a slight deficit in G alpha i1. An ELISA assay using selective antibodies was used to measure [35S]GTP gamma S binding to G alpha o and G alpha i1. Binding was proportional to the concentration of GTP-gamma S and was concentration-dependently stimulated by mastoparan equivalently in control and Alzheimer's disease prefrontal cortical membranes.

Age Factors↗
PubMedDate not supplied

Densitometric analysis of Galphao protein subunit levels from postmortem Alzheimer disease hippocampal and prefrontal cortical membranes.

An immunoblotting method using prefrontal cortical and hippocampal membranes from control and Alzheimer disease postmortem brains was employed to detect three subtypes of Galphao protein. In the membranes from control subjects, the density of Galphao1 in hippocampus and cortex was the highest, whereas the density of Galphao2 was the lowest and that of Galphao3 was intermediate. In the Alzheimer disease membranes from hippocampus, the density of total Galphao and all three subtype forms was not changed significantly when compared with control values. There were statistically significant alterations in Galphao in cortical membranes from Alzheimer disease when compared with controls. The density of Galphao1 was decreased by approximately 85%, density of Galphao3 was decreased by approximately 95%, and total Galphao density was decreased by approximately 84% of control value. However, Galphao2 density was decreased by approximately 44% but was found not to be statistically different from controls.

Aged↗