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Biomedical subjects

R L Wilson

Publications and source records attributed to R L Wilson.

At least 37 records · Page 2Linked to original sources
PubMed1990

Modulation of hippocampal primed burst potentiation by anesthesia.

This study demonstrates that the anesthetics urethane and pentobarbital differentially affect a low threshold form of long-lasting synaptic plasticity, termed primed burst (PB) potentiation, in the CA1 area of rat hippocampus. PB potentiation was generated by the delivery of a 5-pulse patterned stimulus train, consisting of one priming pulse followed 170 ms later by a burst of 4 pulses at 200 Hz. PB potentiation could not be reliably generated in urethane-anesthetized rats unless stimulus currents were raised to 150% of baseline levels during the stimulus train. In pentobarbital-anesthetized rats, PB potentiation could always be evoked at baseline stimulus intensities. Differences between the anesthetics which could contribute to their varying effects upon PB potentiation are discussed.

Action Potentials↗
PubMed1990

Interference by DOPAC and ascorbate during attempts to measure drug-induced changes in neostriatal dopamine with Nafion-coated, carbon-fiber electrodes.

The selectivity of Nafion-coated, carbon-fiber electrodes was evaluated for the voltammetric detection of dopamine in the presence of 3,4-dihydroxyphenylacetic acid (DOPAC) and ascorbate, which are interferant anions in the brain. Nafion coating was applied to both polished carbon-disk electrodes and electrochemically modified electrodes. During in vitro testing, polished disk electrodes showed the greatest selectivity for dopamine at the fastest scan rate tested (300 V s-1), but the drift in signal made slow changes in dopamine difficult to determine. Electrochemically modified electrodes already provide an ascorbate wave distinct from that for dopamine, but Nafion coating actually decreased dopamine selectivity with respect to DOPAC. In vivo testing was carried out in the neostriatum of urethane-anesthetized rats in response to drug- or stimulation-induced increases in dopamine transmission. Administration of haloperidol (0.5 mg kg-1) followed by GBR 12909 (20 mg kg-1), which is known to cause a 10-fold increase in extracellular dopamine, failed to produce a selective signal for dopamine when measured voltammetrically. Comparable results were obtained following administration of amphetamine (2.5 mg kg-1), which also increases dopamine overflow. Voltammetric detection of dopamine was possible, however, during electrical stimulation of dopaminergic afferents in the medial forebrain bundle. Thus, voltammetry with Nafion-coated electrodes is best suited to the measurement of transient changes in extracellular dopamine rather than the relatively prolonged changes in dopamine overflow produced by various drugs.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

The rheumatoid metacarpophalangeal joint.

Reconstruction of the MP joint affected by rheumatoid disease can pose a challenge to the surgeon and therapist. The multiple initiating and aggravating factors must be taken into consideration during the planning phase before they can be addressed surgically. The results following surgery at the MP joint are dependent on a number of factors. The most important of these is the general activity of the rheumatoid disease and the patient's response to medical treatment. The individual who requires steroids and antimetabolites may observe a general worsening of his disease state, which will be uninfluenced by surgery at the MP joints. Patients demonstrating vasculitis may have problems with wound healing and remobilization following MP joint surgery. The surgeon's ability to rebalance the MP joint is directly related to the quality of the periarticular soft tissues needed for the reconstructive procedure. The ability of an individual to cooperate in a postoperative program and to apply the principles of joint protection is absolutely necessary. The eventual joint motion is related to tendon function in the hand.

Arthritis, Rheumatoid↗
PubMed1988

Choosing the right severity system.

Patient severity, and its measurement, has become a central issue in understanding the interrelationships and trade-offs between costs and quality. This article offers a balanced framework within which all severity-measurement systems can be evaluated.

Data Collection↗
PubMed1987

Comparison of induced corpora lutea from prepuberal gilts and spontaneous corpora lutea from mature gilts: in vitro progesterone production.

Prepuberal (P) gilts were induced to ovulate with pregnant mare serum gonadotropin followed 72 h later by human chorionic gonadotropin (hCG). Three P gilts and three mature (M) gilts each were ovariectomized on d 10, 14, 18, 22 and 26 (d 0 = day of hCG for P gilts and onset of estrus for M gilts). Gilts ovariectomized on d 14, 18, 22 and 26 were hysterectomized on d 6 to ensure maintenance of the corpora lutea (CL). Two to five grams of minced luteal tissue were dispersed using collagenase and hyaluronidase in HEPES buffered salt solution supplemented with glucose and bovine serum albumin. Dispersed cells were rinsed in Dulbecco's Modified Eagle Medium (DMEM), counted (ratio of large to total number of luteal cells determined) and then incubated for 1 h in DMEM. With aliquots standardized to 2.5 X 10(4) viable, large cells (greater than 25 micron diameter) were incubated in 1 ml DMEM for 2 h in the presence of either 10, 50, 100 or 1,000 ng luteinizing hormone (LH); .1, 1, 10 or 100 ng hCG; 10, 100 or 1,000 ng norepinephrine (NE) or either .75, or 1.5 mM dibutyrl cyclic adenosine monophosphate (dbcAMP). Progesterone (P4) in the medium was quantified by radioimmunoassay. Basal P4 production (no P4 stimulator added to the medium) on d 10, 14, 18, 22 and 26 for P gilts was 246 +/- 9, 66 +/- 4, 64 +/- 6, 41 +/- 3 and 69 +/- 6 ng/ml medium, respectively, and for M gilts was 281 +/- 12, 128 +/- 8, 53 +/- 4, 82 +/- 6, 101 +/- 5 ng/ml medium, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Unilateral, intranigral infusions of amphetamine produce differential, bilateral changes in unit activity and extracellular levels of ascorbate in the neostriatum of the rat.

Simultaneous recordings of single-unit activity and oxidation current were obtained bilaterally from the neostriatum of rats in response to a unilateral infusion of D-amphetamine (2.0 microliters of 10 micrograms/microliter) into the substantia nigra. Whereas neuronal activity increases ipsilaterally and decreases contralaterally, the electrochemical signals, which reflect extracellular ascorbate, increase bilaterally. In each case, changes in unit activity precede the change in ascorbate release. Systemic administration of haloperidol (0.2 mg/kg) blocks the increase in oxidation current bilaterally, but reverses the neuronal activity response only on the ipsilateral side. These results lend further support to the view that intranigral amphetamine facilitates neostriatal ascorbate release, but this effect is not correlated with changes in single-unit activity.

Animals↗
PubMed1986

Crus cerebri lesions abolish amphetamine-induced ascorbate release in the rat neostriatum.

An increase in the concentration of ascorbate in the extracellular fluid of the rat striatum following systemic amphetamine administration previously has been demonstrated with the use of in vivo electrochemistry, push-pull cannula and in vivo dialysis. In this report, the effect of infusions of amphetamine into the substantia nigra on extracellular ascorbate levels in the striatum is further investigated by in vivo electrochemistry. Electrolytic lesions in the crus cerebri of the striatonigral pathway abolish this effect. Furthermore, these lesions abolish the effect of systemic amphetamine in the striatum ipsilateral to the lesion but not on the contralateral side. This phenomenon is independent of neostriatal dopamine or gamma-aminobutyric acid since levels were shown to be unchanged relative to the intact side. These results lend further support to the hypothesis that ascorbate secretion in the striatum after amphetamine is mediated in the central nervous system, and indicate that a pathway that courses through the crus cerebri is necessary for this release.

Amphetamine↗
PubMed1986

Multiple amphetamine injections reduce the release of ascorbic acid in the neostriatum of the rat.

Voltammetric signals were recorded bilaterally with unmodified or electrochemically-modified carbon-fiber electrodes in the neostriatum of rats that sustained a unilateral depletion of dopamine by pretreatment with 6-hydroxydopamine. In both hemispheres, single daily injections of D-amphetamine (5.0 mg/kg or steadily increasing doses beginning with 6.0 mg/kg) for 6 consecutive days significantly reduced the rise in oxidation current produced by a challenge injection of 2.5 mg/kg D-amphetamine compared to the response obtained from saline-treated controls. Voltammetric scans indicated that the oxidized substance shared the electrochemical characteristics of ascorbic acid. It appears, therefore, that multiple amphetamine injections reduce the release of ascorbic acid in the neostriatum and that this effect does not depend on the integrity of dopaminergic neurons.

Amphetamine↗
PubMed1986

Substrate utilization by fetal pig skeletal muscle.

The ability of fetal pig skeletal muscle (biceps femoris) to metabolize glucose, fructose, lactate, acetate and palmitate in vitro was examined at 70, 90 and 110 d of gestation. Even though succinate dehydrogenase activity increased as fetal age increased (P less than .01), the rate of oxidation of glucose, fructose, acetate and palmitate to CO2 was not influenced by fetal age (P greater than .05), but each rate was dose-dependent (P less than .01). At higher concentration, lactate oxidation to CO2 proceeded at a faster rate in the muscle of 70-d fetuses when compared with 90- or 110-d fetuses. Muscle glycogen content increased (P less than .01) from 70 to 110 d of gestation. The rate of glucose incorporation into glycogen increased over this same time frame (P less than .06). Glucose-6-phosphate dehydrogenase activity did not change with age when activity was expressed per unit wet weight of muscle (P greater than .05). The ratio [1-14C]glucose/[6-14C]glucose oxidized to CO2 was independent of age and substrate concentration, and indicated significant pentose cycle activity in fetal muscle. Incorporation of lactate and palmitate into phospholipid was greatest at 70 d of gestation, a time period that coincides with establishment of mature muscle fiber number and fiber hypertrophy. The rate of palmitate incorporation into triacylglycerol was dependent on concentration of substrate (P less than .01) but not on age (P greater than .05). The rate of fructose oxidation to CO2 was lower than the rate for glucose, lactate and acetate when compared at similar concentrations. Acetate carbons were not incorporated into free fatty acids or lipid.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1986

Complications following small joint injuries.

Injuries to the small joints in the hand can lead to stiffness, pain, instability, and arthrosis. Careful evaluation and an understanding of possible complications may prevent serious difficulties from occurring.

Edema↗
PubMed1986

Rheumatoid arthritis of the hand.

Rheumatoid arthritis often begins in the hand, and upper extremity function can be seriously impaired with progression of the disease. When numerous areas are involved, a multitude of deformities can arise. Before initiating treatment of an arthritic patient, the surgeon must understand the natural course of the disease process, the response to medical treatment, and the functional limitations the disease has imposed. This article describes the examination for and treatment of this disease.

Arthritis, Rheumatoid↗
PubMed1985

Systemic and nigral application of amphetamine both cause an increase in extracellular concentration of ascorbate in the caudate nucleus of the rat.

Unmodified microvoltammetric electrodes and electrochemically modified cylindrical electrodes, both constructed from carbon fibers, were used to determine changes in ascorbate concentration in the caudate nucleus of the anesthetized rat following administration of amphetamine. The increased ascorbate levels with systemic amphetamine originate from a CNS source, since the response is not eliminated in adrenalectomized animals, and does not occur when p-hydroxyamphetamine, an agent with peripheral actions similar to amphetamine, is used as a stimulus. Local application of amphetamine in the caudate nucleus results in an increase in catechols. However, this procedure results in a decrease of the extracellular concentration of ascorbate. Unilateral nigral infusion of dopamine or amphetamine leads to a significant increase in the concentrations of ascorbate detected bilaterally in the caudate nuclei with in vivo electrochemistry. In contrast, the paradigm causes a decrease in extracellular catechols on the ipsilateral side and an increase on the contralateral side. These experiments demonstrate that the extracellular level of ascorbate is not correlated with dopamine secretion. Furthermore, the data show that the action of amphetamine on ascorbate concentration in the caudate nucleus is in part mediated by the nigral actions of amphetamine.

Adrenal Glands↗