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Biomedical subjects

S Ferguson

Publications and source records attributed to S Ferguson.

At least 55 records · Page 3Linked to original sources
PubMed1994

Automating the generation and collection of rate-frequency functions in a curve-shift brain stimulation reward paradigm.

The electrical self-stimulation paradigm has proven to be very useful in research aimed at delineating the neural substrates involved in reward-related learning. Of the procedures currently employed the curve-shift method is among the more useful since it distinguishes between treatment effects on reward and performance. This method involves generating and plotting rate-frequency functions and quantifying the effects of experimental manipulations on reward by measuring the degree of lateral shift in these functions. We have designed a computerized system that automatically generates and collects descending rate-frequency functions from self-stimulating rats. The 3 main units of this system consisted of a 6809 micro-controller, a programmable timer logic board and a constant current source. The micro-controller and programmable timer operated on custom written software that monitored lever pressing in the operant chambers and controlled stimulation parameters to generate and record rate-frequency functions. The present report describes this system and presents some typical data collected from rats self-stimulating on ventral tegmental electrodes before and after the administration of intra-accumbens vehicle (0.5 microliter distilled H2O), (+)-amphetamine (20.0 micrograms/0.5 microliter), quinpirole (10.0 micrograms/0.5 microliter) and systemic quinpirole (1.0 mg/kg), all dopamine agonists. Stimulation consisting of 300-ms trains of cathodal rectangular pulses (0.1 ms) was available in 50-s trials. The number of pulses per train was decreased logarithmically from a value that sustained maximal responding to one that would not sustain responding. Self-stimulation thresholds were obtained by fitting the Gompertz growth model to the data and calculating the point of maximal acceleration of the sigmoidal curve. It was found that the present system generated and collected rate-frequency functions similar to those that have been obtained manually in previous experiments. The data showed that the system was sensitive to both central and systemic pharmacological manipulations by producing lateral and vertical shifts of the rate-frequency functions, indications of reward and motor effects, respectively. It was concluded that the present design was useful in conducting entire self-stimulation sessions that required minimal monitoring by the experimenter.

Amplifiers, Electronic↗
PubMed1994

Monoplegia following carotid sinus massage.

Serious complications after carotid sinus massage are rare. A case is described of monoplegia complicating carotid sinus massage in an elderly patient without symptoms or signs of cerebrovascular disease. We remind physicians of this potential complication and suggest that alternative therapies be considered prior to the use of carotid sinus massage in this age group.

Aged↗
PubMed1993

Observing and imitating the formation of object classes during the second year of life.

The developmental origins of overt object classification are still poorly understood, but one factor that may be informative and facilitative of classification during the second year is observing adults group similar objects. A pretest-posttest design with modeling and control groups was used to assess the impact of modeling on deferred imitation of groupings based on object similarity. Children at three ages (12, 18, and 24 months) observed an adult produce class groupings and alignments of objects. By 18 and 24 months, there was significant deferred imitation of object groupings. There was virtually no effect at 12 months. Moreover, only at 24 months were classified sets spatially aligned. The results indicate that observing adult classification will at least facilitate object grouping during the latter part of the second year, and that it may promote the use of spatial alignments as organizing devices or as modes of depicting object classes.

Child, Preschool↗
PubMed1993

Knowledge and skills needed for collaborative work.

The need for collaboration and cooperation in health care delivery is not news. But one of the first requests often made by leaders and others promoting collaborative work in organizations is for a "facilitator course." As the authors developed more knowledge about the real need, they understood that many of the barriers to collaborative work and learning in organizations can be reduced only by the top leaders, not by expert facilitators. The central knowledge that leaders need to support collaborative work is appreciation of work as a system.

Communication↗
PubMed1993

Low dose rate teletherapy and tumour response.

Tumour responses in 25 patients with locally advanced head and neck cancer, treated on an experimental fractionated low dose rate (FLDR) teletherapy program are reported. Treatment was given at dose rates ranging from 1.8 to 3 Gy/h to a range of total doses from 32-38 Gy, with palliative intent. The total doses delivered have been predicted by the linear quadratic formula to be equivalent to 33-41 Gy using conventionally fractionated high dose rate treatment, in terms of acute normal tissue effects. A complete response rate (no visible or palpable disease 2 months after treatment) was observed in 28% of cases. Analysis of these response rates suggests that the linear quadratic formula may underestimate the anti-tumour effect of FLDR teletherapy at the various dose rates and total dose permutations in this study.

Carcinoma, Squamous Cell↗
PubMed1992

Dissociation of mechanisms of reading in Alzheimer's disease.

The role of spelling-to-sound correspondence rules in oral word reading was investigated by asking patients with Alzheimer's Disease (AD) and normal controls to read aloud pronounceable letter strings that do not happen to be real words. These pseudowords were of two types: those that have orthographically similar "neighbors," and those that have no neighbors. The patients with AD were mildly impaired relative to the normal controls in reading pseudowords with neighbors, but were markedly impaired in reading pseudowords with no neighbors. The results are interpreted as favoring a model of reading in which words and pseudowords are normally read via the same lexical mechanism. An ancillary route involving the conscious application of spelling-to-sound rules is available only to cognitively intact readers.

Aged↗
PubMed1991

Do surgical gloves protect staff during electrosurgical procedures?

Fifteen pair of commercially available gloves were tested under conditions that occur during radio frequency electrosurgery to determine their potential to cause burns or shocks. Two pair of gloves showed a hydration effect that produced sufficiently low direct current resistance, 1500 and 5000 ohms, to be a potential shock or burn hazard. All intact gloves passed in excess of 0.75 A of radio frequency current by capacitive coupling. Eleven pair of gloves displayed dielectric breakdown of the latex or neoprene at voltages between 2200 and 2600 volts; the remaining gloves ranged from 5800 to 7000 volts. Under specific conditions all gloves tested have the potential to cause burns or shocks to the surgeon during electrosurgical procedures. To avoid burns, shocks, or glove perforation, surgeons should be aware of situations that put them at high risk.

Burns↗
PubMed1990

Low dose rate teletherapy using a telecaesium 137 unit radiobiological, physical and clinical considerations.

Low dose rate teletherapy aims to combine the supposedly superior results obtained with low dose rate implants with the convenience and staff protection characteristics of external beam therapy. Previous investigators have used telecobalt units to produce dose rates of 1.1 to 1.8 Gy/hr to treat in daily sessions lasting 6-10 hours to total doses of 60-70 Gy. These studies have not discounted the possibility that much of the advantage of interstitial implants results from the low dose rates used per se, and from the fact that the total dose is delivered in a short overall time. The relationship between total dose, dose rate and volume giving normal tissue and anit-tumour effects, however, remains ill-defined. At the Newcastle Mater Misericordiae Hospital a Caesium teletherapy unit has been modified to treat at low dose rates and a study has been designed with a view to establish which permutations of total dose and dose rate are isoeffective for acute mucosal and acute skin reactions in the dose rate range between 0.8 and 9.6 Gy/hr (1.3 and 16 cGy/min).

Cesium Radioisotopes↗
PubMed1989

Integrating nursing theory, practice and research through collaborative research.

The advancement of professional nursing requires integration of theory, practice and research. One realistic mechanism to achieve this integration is collaborative nursing research. A collaborative experience between clinical nurse specialists and faculty researchers is described and evaluated. The collaborative research project focused on contraceptive nursing care and self-care conceptualized within Orem's theory. A major finding was that while job titles and settings of the participants differed markedly, role components were not disparate; rather, they were compatible and complementary. The collaborative project strengthened both the theory base for a primary care nursing practice and the practice base for faculty research and theory development efforts.

Clinical Nursing Research↗
PubMed1988

Investigation by electron paramagnetic resonance spectroscopy of the molybdenum centre of respiratory nitrate reductase from Paracoccus denitrificans.

The molybdenum centre of respiratory nitrate reductase from Paracoccus denitrificans has been investigated by e.p.r. spectroscopy of Mo(V). In common with the centres of the analogous enzymes from Escherichia coli and Pseudomonas aeruginosa, it undergoes a pH- and anion-dependent transition between two different e.p.r. signal-giving species. Comparison of the relevant e.p.r. parameters extracted with the help of computer simulations reveals ligation of the metal in the active centres of the three enzymes to be identical.

Electron Spin Resonance Spectroscopy↗
PubMed1986

Capillary gas chromatography-mass spectrometry of valproic acid metabolites in serum and urine using tert.-butyldimethylsilyl derivatives.

A quantitative method has been developed for valproic acid and twelve of its metabolites using capillary gas chromatography--mass spectrometry with selected-ion monitoring. The method is applicable to serum or urine and all metabolites are measured in a single run. Ions selected for quantitative purposes were the characteristic (M-57)+ ions of the tert.-butyldimethylsilyl (tBDMS) derivatives. The 4-hydroxyvalproic acid was measured as the gamma-lactone. Calibration curves were found to be linear and the sensitivities in the order of 0.1 microgram/ml. Patient data are presented. A comparison of tBDMS and trimethylsilyl (TMS) derivatives showed that tBDMS gave superior sensitivity for the unsaturated metabolites and a shorter analysis time. Mixed tBDMS-TMS derivatives were also investigated.

Gas Chromatography-Mass Spectrometry↗
PubMed1983

The effects of peritoneal dialysis on the single dose and steady state pharmacokinetics of valproic acid in a uremic epileptic child.

The pharmacokinetics of valproic acid (VPA) have been studied during peritoneal dialysis in a uremic male epileptic child following a single 500 mg dose and after multiple doses over 5 months (700 mg daily) of valproic acid as the syrup. Serum level decline was biphasic in both instances with a terminal half-life of 27.2 after the single dose and 10.2 h at steady-state. Total serum clearance was 0.0236 l/h/kg after the single dose and increased to 0.0408 l/h/kg after 5 months. Free (intrinsic) serum clearances were 0.1489 and 0.1518 l/h/kg and serum free fractions were 0.224 and 0.272 respectively for the single dose and steady-state studies. Peritoneal dialysis for periods of 12 or 24 h removed an average of 4.5% of the VPA dose.

Child↗