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Biomedical subjects

R Bray

Publications and source records attributed to R Bray.

36 records · Page 2Linked to original sources
PubMed1988

4-Hydroxynonenal: a specific indicator for canine neuronal-retinal ceroidosis.

Previous attempts to demonstrate abnormalities in lipid peroxidation in various forms of the neuronal ceroid-lipofuscinoses (NCL) have been unrewarding up to and including the peroxide level (peroxidase). In this experiment a survey was made in a canine model of NCL to study the relative concentration of 4-hydroxynonenal (HNE), a fragment derived from an acute oxidation product of unsaturated fatty acids. Peripheral blood cells and various tissues from an affected and a normal control dog were surveyed. HNE was assayed after reacting with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine to form the 4-hydroxynonenal (O-pentafluorobenzyl) oxime. This reaction product was then separated by capillary gas liquid chromatography (g/c) and quantitated by flame ionization. The survey showed that neutrophils isolated from affected dogs and carriers contained abnormal amounts of HNE when compared with normal control animals. Two carriers had mean values of +3,289% above normal, and neutrophils from two affected animals were +4,873% above normal. In addition, an examination of the relative HNE levels in brain, retina, retinal pigment epithelium (RPE), and kidney of an affected dog compared with a control animal also showed abnormal levels of HNE, particularly in brain (+168%) and in the RPE (+135%), the two organs exhibiting the most severe pathologic damage unique to these disorders. These findings, although preliminary, clearly document a role for HNE in this canine form of human NCLs. The well-known cytotoxic properties of HNE and other alpha,beta unsaturated aldehydes suggest a primary role in the pathogenetic events of this disorder.

Aldehydes↗
PubMed1988

Psychophysical evidence for an extrastriate contribution to a pattern-selective motion aftereffect.

A stationary vertical test grating appears to drift to the left after adaptation to an inducing grating drifting to the right, this being known as the motion aftereffect (MAE). Pattern-specific motion aftereffects (PSMAEs) induced by superimposed pairs of gratings in which the component gratings drift up and down but the observer sees a single coherent plaid drifting to the right have been investigated. Two experiments are reported in which it is demonstrated that the PSMAE is tuned more to the motion of the pattern than to the orientation and direction of motion of the component gratings. However, when subjects adapt to the component gratings in alternation, aftereffect magnitude is dependent upon the individual grating orientations and motion directions. These results can be interpreted in terms of extrastriate contributions to the PSMAE, possibly arising from the middle temporal area, where some cells, unlike those in striate cortex (V1), are tuned to pattern motion rather than to component motion.

Figural Aftereffect↗
PubMed1987

Isolation and characterization of Pseudomonas putida R-prime plasmids.

A number of enhanced chromosome mobilizing (ECM) plasmids derived from the wide host range plasmid R68 have been used to construct R-prime plasmids carrying a maximum of two map minutes of the Pseudomonas putida PPN chromosome, using Pseudomonas aeruginosa PAO as the recipient. For one ECM plasmid, pMO61, the ability to form R-primes did not correlate with the ability to mobilize chromosomes in intrastrain crosses, suggesting that different mechanisms are involved. Physical analysis of one R-prime showed that 3.5 kb of chromosomal DNA had been inserted between the tandem IS21 sequences carried by the parent ECM plasmid.

Chromosome Mapping↗
PubMed1983

Studies on the mechanism of human natural killer cell-mediated cytolysis. I. Modulation by dexamethasone and arachidonic acid.

Natural killer (NK) cell-mediated cytotoxicity, as measured by the lysis of the human erythroleukemic cell line K562, is inhibited by the glucocorticosteroid dexamethasone (DEX). Kinetic analysis revealed that DEX inhibits an early event(s) in the lytic mechanism and that the inhibition is both transient and readily reversible if DEX is removed. The inhibition is not due to the production of a DEX-induced inhibitory protein or decreased target-cell binding. Attempts to counter the effects of DEX through the addition of inducers of NK activity were unsuccessful. Neither the calcium ionophore A23187 nor exogenous cyclic GMP was able to reverse the inhibition by DEX. The addition of arachidonic acid (AA), a pharmacologically active metabolite of phospholipase A-2 activation, was also unsuccessful in reversing the effects of DEX. In fact, AA itself inhibited NK activity in a dose-dependent fashion. This inhibition was not due to reduced target binding and was observed even in the presence of indomethacin. It is concluded that DEX blocks an early membrane-signaling event necessary to activate the lytic mechanism and that inhibition was not through some alternative mechanism. Inhibition of NK activity by arachidonic acid is not yet understood but most likely is not a result of enhanced prostaglandin synthesis. Hence, the study of DEX and AA inhibition provides a new approach to unravel some of the intricacies surrounding NK-mediated tumor target destruction.

Arachidonic Acid↗
PubMedDate not supplied

Decrease in quadriceps inhibition after sacroiliac joint manipulation in patients with anterior knee pain.

BACKGROUND: Evidence exists that conservative rehabilitation protocols fail to achieve full recovery of muscle strength and function after joint injuries. The lack of success has been attributed to the high amount of muscle inhibition found in patients with pathologic conditions of the knee joint. Clinical evaluation shows that anterior knee pain is typically associated with sacroiliac joint dysfunction, which may contribute to the muscle inhibition observed in this patient group. OBJECTIVE: To assess whether sacroiliac joint manipulation alters muscle inhibition and strength of the knee extensor muscles in patients with anterior knee pain. DESIGN AND SETTING: The effects of sacroiliac joint manipulation were evaluated in patients with anterior knee pain. The manipulation consisted of a high-velocity low-amplitude thrust in the side-lying position aimed at correcting sacroiliac joint dysfunction. Before and after the manipulation, torque, muscle inhibition, and muscle activation for the knee extensor muscles were measured during isometric contractions using a Cybex dynamometer, muscle stimulation, and electromyography, respectively. PARTICIPANTS: Eighteen patients (mean age, 30.5 +/- 13.0 years) with either unilateral (n = 14) or bilateral (n = 4) anterior knee pain. RESULTS: Patients showed substantial muscle inhibition in the involved and the contralateral legs as estimated by the interpolated twitch technique. After the manipulation, a decrease in muscle inhibition and increases in knee extensor torques and muscle activation were observed, particularly in the involved leg. In patients with bilateral anterior knee pain, muscle inhibition was decreased in both legs after sacroiliac joint adjustment. CONCLUSIONS: Spinal manipulation might offer an interesting alternative treatment for patients with anterior knee pain and muscle inhibition. Because this clinical outcome study was of descriptive nature rather than a controlled design, biases might have occurred. Thus the results have to be verified in a randomized, controlled, double-blinded trial before firm conclusions can be drawn or recommendations can be made.

Adult↗
PubMedDate not supplied

Performance and sensitivity of modern home pregnancy tests.

We have studied the performance of three currently available home pregnancy tests. The Advance is a test based on monoclonal antibodies in an enzyme immunoassay format that specifically detects hCG in urine. The positive results are determined by the presence of a blue color in a color stick (30 minutes). The Daisy 2 and FACT are tests based on monoclonal antibodies that specifically detect hCG in urine in a hemagglutination inhibition assay; positive results are demonstrated by the deposition of a dot ring at the bottom of the test tube (45 minutes). Thirty-five patients who eventually became pregnant in that cycle collected the first morning urine specimens from day of ovulation (determined by ultrasound) in artificial insemination donor (AID) cycles, or from the date of gamete intrafallopian transfer (GIFT) for 16 consecutive days. In each specimen, the Advance, Daisy 2, and FACT tests were performed; in addition, beta-hCG levels were determined by radioimmunoassay. All the home pregnancy tests studied can detect pregnancy as early as 9 or 10 days post-conception, and they give positive results at the time of the expected onset of menses in 70%, 95%, and 88% of cases for Daisy 2, Advance, and FACT, respectively. The sensitivity of the these home pregnancy tests was determined to be about 200 mIU/mL of urine after correlating their positive or negative results with the concentrations of urinary beta-hCG determined by radioimmunoassay.

Antibodies, Monoclonal↗