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Biomedical subjects

D W Griffin

Publications and source records attributed to D W Griffin.

15 recordsLinked to original sources
PubMed1992

Prevalence of bacterial urinary tract infection after perineal urethrostomy in cats.

It has been reported that the prevalence of bacterial urinary tract infection (UTI) increases after perineal urethrostomy in male cats. Perineal urethrostomy, using a surgical technique preserving striated urethral sphincter function, was performed on 2 groups of cats. The first group consisted of healthy castrated cats. The second group of cats had recurrent or persistent urethral obstruction. All cats had normal urethral sphincter function after surgery, as measured by urethral pressure profilometry and electromyography. Long-term periodic urinalysis and bacterial culturing of urine was performed on all cats. Twenty-two percent of the previously obstructed cats had recurrent bacterial UTI, compared with none of the healthy cats. On the basis of these findings, we suggest that perineal urethrostomy per se does not predispose cats to bacterial UTI, but surgical alteration of the urethral meatus combined with an underlying uropathy may increase the prevalence of ascending bacterial UTI after surgery.

Animals↗
PubMed1991

Diurnal responses of mammals to acute exposure to a hyperdynamic environment.

Acute exposure to hyperdynamic environments elicits significant depressions in core temperature in both diurnal squirrel monkeys and nocturnal rats. This study describes time of day variations in core temperature responses in squirrel monkeys and rats exposed for 70 min to a hyperdynamic environment (2 g) produced via centrifugation. Experiments were performed during the middle of the light or dark phase. After a 70-min control period, squirrel monkey resting core temperature was 38.6 +/- 0.2 (SE) and 36.8 +/- 0.2 degrees C during the day and night, respectively. At the end of a 7-min exposure to 2 g, squirrel monkey core temperature decreased 1.3 +/- 0.2 degree C during the day but remained a constant 36.8 +/- 0.4 degrees C at night. Core temperature of rats exposed to an identical 70-min 2 g profile decreased 1.5 +/- 0.4 degree C from a resting 37.1 +/- 0.6 degrees C during the day and 2.3 +/- 0.2 degrees C from a resting 37.8 +/- 0.3 degrees C at night. Thus, in both species, there were clear day-night differences in response to hyperdynamic environments, with the greatest fall in core temperature occurring during the animal's active period.

Adipose Tissue, Brown↗
PubMed1990

The overconfidence effect in social prediction.

In five studies with overlapping designs and intents, subjects predicted a specific peer's responses to a variety of stimulus situations, each of which offered a pair of mutually exclusive and exhaustive response alternatives. Each prediction was accompanied by a subjective probability estimate reflecting the subjects' confidence in its accuracy--a measure validated in Study 5 by having subjects choose whether to "gamble" on the accuracy of their prediction or on the outcome of a simple aleatory event. Our primary finding was that in social prediction, as in other judgmental domains, subjects consistently proved to be highly overconfident. That is, regardless of the type of prediction item (e.g., responses to hypothetical dilemmas, responses to contrived laboratory situations, or self-reports of everyday behaviors) and regardless of the type of information available about the person whose responses they were predicting (e.g., predictions about roommates or predictions based on prior interviews), the levels of accuracy subjects achieved fell considerably below the levels required to justify their confidence levels. Further analysis revealed two specific sources of overconfidence. First, subjects generally were overconfident to the extent they were highly confident. Second, subjects were most likely to be overconfident when they knowingly or unknowingly made predictions that ran counter to the relevant response base rates and, as a consequence, achieved low accuracy rates that their confidence estimates failed to anticipate. Theoretical and normative implications are discussed and proposals for subsequent research offered.

Adult↗
PubMed1990

Overconfident prediction of future actions and outcomes by self and others.

In a follow-up study to Dunning, Griffin, Milojkovic, and L. Ross (1990), which had investigated the phenomenon of overconfidence in social prediction, two samples of first-year undergraduates were invited to make predictions about their own future responses (and, in the case of Sample 2, also those of their roommates) over the months ahead. These predictions were accompanied by confidence estimates and were evaluated in the light of actual responses reported later by the subjects in question. The primary finding was that self-predictions, like social predictions, proved to be consistently overconfident. As in Dunning et al., moreover, overconfidence could be traced to two sources. First, expressions of particularly high confidence rarely proved to be warranted; as confidence increased, the gap between accuracy and confidence widened. Second, predictions that went against relevant base rates yielded very low accuracy in the face of relatively unattenuated confidence levels. The implications of these results are discussed, and one potentially important underlying mechanism--the failure to make adequate inferential allowance for the uncertainties of situational construal--is proposed for further research.

Choice Behavior↗
PubMed1990

The role of construal processes in overconfident predictions about the self and others.

Overconfident behavioral predictions and trait inferences may occur because people make inadequate allowance for the uncertainties of situational construal. In Studies 1-3, Ss estimated how much time or money they would spend in various hypothetical, incompletely specified situations. Ss then offered associated "confidence limits" under different "construal conditions". In Study 4, Ss made trait inferences about someone they believed had responded "deviantly"--again with situational details unspecified and construal conditions manipulated. In all 4 studies, Ss who made predictions or trait inferences without being able to assume the accuracy of their situational construals offered confidence limits no broader than those of Ss who made their responses contingent on such accuracy. Only in conditions where Ss were obliged to offer alternative construals did they appropriately broaden their confidence limits or weaken their trait inferences.

Adult↗
PubMed1989

Preservation of striated-muscle urethral sphincter function with use of a surgical technique for perineal urethrostomy in cats.

It has been reported that perineal urethrostomy resulted in impairment of striated-muscle urethral sphincter function in male cats, as measured by urethral pressure profilometry and electromyography (EMG). Our study was undertaken to describe and evaluate a surgical technique for perineal urethrostomy that reduces trauma to the urethral branches of the pudendal nerve. Perineal urethrostomy was performed on 10 healthy neutered cats after demonstrating that they had normal urethral sphincter function by urethral pressure profilometry (maximal urethral closure pressure [MUCP] = 151 +/- 52 cm of water) and EMG activity at the level of the striated-muscle sphincter before surgery. All cats had normal urethral sphincter function 1 week (MUCP = 194 +/- 19 cm of water, EMG activity present) and 3 weeks (MUCP greater than 200 cm of water, EMG activity present) after surgery. These results indicated that preservation of the urethral branches of the pudendal nerve during urethrostomy preserved striated-muscle urethral sphincter function.

Animals↗
PubMed1989

Effect of metal-framed spectacles on microwave radiation hazards to the eye of humans.

A novel measurement technique using a monopole antenna probe has been applied to a full-size, image-plane type model of a human to determine the microwave fields near the eyes and to evaluate the effect of scattering structures, such as metal-framed spectacles, on those fields. The measurement technique relies on a 'subtraction' technique to determine the changes in fields when a scattering structure is introduced, and allows a large number of measurements to be performed in a relatively short space of time and with a high degree of accuracy. Investigations conducted in an anechoic chamber yield angles of incidence, test frequencies and wave polarisation values that give details of shielding, enhancement and depolarisation effects due to this particular scattering structure that appeared not to have been previously studied. It has been found that the introduction of a pair of metal-framed spectacles can, in certain cases, cause an increase in field levels by up to approximately 20 dB, a significant perturbation of the incident microwave field which should be accounted for in the setting of safety standards relating to acceptable levels of incident power.

Eye↗
PubMed1989

Scatchard analysis of methane sulfinic acid production from dimethyl sulfoxide: a method to quantify hydroxyl radical formation in physiologic systems.

A major impediment to the confirmation of free radical mechanisms in pathogenesis is a lack of direct, chemical evidence that oxygen centered free radicals actually arise in living tissues in quantities sufficient to cause serious damage. This investigation was conducted to validate the use of dimethyl sulfoxide (DMSO) as a quantitative molecular probe for the generation of hydroxyl radicals (HO.) under physiologic conditions. Reaction of HO. with DMSO produces methane sulfinic acid (MSA) as a primary product, which can be detected by a simple colorimetric assay. To develop a method for estimating total HO. production, we studied two model systems: the superoxide driven Fenton reaction in vitro, using xanthine oxidase as the source of superoxide, and a computer model of Fenton chemistry. Measured MSA production both in vitro and in the computer model was a predictable function of the concentrations of DMSO and competing scavengers of HO., according to the principle of competition kinetics. Both experimental results and model calculations showed that Scatchard analysis may be used to infer total HO. generation, despite the presence of scavengers other than DMSO, such as mannitol. Thus, methane sulfinic acid production from DMSO holds promise as an easily measured marker for HO. formation in biologic systems pretreated with DMSO, and Scatchard analysis of repeated experiments with varying DMSO concentrations can yield an estimate of total HO. generation.

Colorimetry↗
PubMed1989

Eructation of gas through the gastroesophageal sphincter before and after limiting distension of the gastric cardia or infusion of a beta-adrenergic amine in dogs.

Gas eructation function of the gastroesophageal sphincter (GES) was investigated in 6 conscious dogs before and after a sleeve was placed around the GES and gastric cardia and during IV infusion of a beta-adrenergic amine (epinephrine). To induce eructation, nitrogen gas was insufflated (351.4 +/- 2 ml/min; mean +/- SEM) into the stomach through 1 channel of a 4-lumen catheter. After baseline studies and epinephrine infusion studies were completed in each dog, surgery was done to limit partially gastric distension by intraluminal contents by placing a silicone rubber sleeve around the GES and the first few centimeters of the cardia. Gastroesophageal sphincter pressure was 31.8 +/- 2.2 mm of Hg in baseline studies, 17.3 +/- 1.3 mm of Hg during epinephrine infusion (P. less than 0.003), and 30.3 +/- 2.2 mm of Hg after the sleeve was placed around the GES and cardia. During insufflation, gastric pressures before eructation increased to 5.74 +/- 0.41 mm of Hg before and to 15.15 +/- 1.63 mm of Hg after cardia sleeve placement (P less than 0.001). Eructation occurred at intervals of 1.83 +/- 0.41 minutes before cardia sleeve placement, and eructations were not observed with the sleeve in place. Before the sleeve was placed, administration of epinephrine resulted in an eructation interval of 0.84 +/- 0.09 minutes, which was significantly different from that in the same dogs given no drugs (P less than 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Interrelations between serum gastrin levels, gastric emptying and acid output before and after proximal gastric vagotomy and truncal vagotomy and antrectomy.

In a prospective study of proximal gastric vagotomy and truncal vagotomy and antrectomy measurements were made, before and after operation, of acid output, gastrin output and gastric emptying of a solid and a liquid meat extract meal. No relationships were demonstrable between acid output and gastrin output. Truncal vagotomy and antrectomy (TVA) produced rapid early emptying of both meals combined with gross prolongation of the overall emptying of the solid meal. Truncal vagotomy and antrectomy reduced the intergrated gastrin output after either meal. Proximal gastric vagotomy (PGV) produced rapid early emptying of the liquid meal with no alteration in the early emptying of the solid meal; however, overall solid meal emptying was delayed. Proximal gastric vagotomy increased basal, peak and integrated gastrin output. In preoperative patients slow solid meal emptying was associated with higher gastrin output but after PGV the reverse was found, the slowest emptiers having the lowest gastrin output. These findings do not support the contention that a pyloroplasty should be added to PGV to reduce the hypergastrinaemia produced by the operation.

Clinical Trials as Topic↗
PubMed1977

Abnormalities of gastric emptying and pyloric reflux in uncomplicated hiatus hernia.

We have measured the rate of gastric emptying of solid and liquid meals by an external scanning technique and have studied pyloric reflux by a radiological technique. Investigations were performed in patients with uncomplicated hiatal hernia, patients with uncomplicated duodenal ulcer and normal controls. There was a significant delay in the emptying of both solid and liquid meals in the patients with hiatal hernia compared with both the duodenal ulcer patients (solid meals P less than 0.01, liquid meals P less than 0.025) and with normal controls (solid meals P less than 0.05, liquid meals P less than 0.001). Duodenogastric reflux was observed in 35% of hiatal hernia patients compared with 24% of duodenal ulcer patients and no incidence in the controls.

Gastric Emptying↗
PubMed1976

The association of duodenogastric reflux with dumping and gastric retention.

Gastric emptying of solid and liquid meals together with duodenogastric reflux has been measured in a prospective trial of proximal gastric vagotomy and truncal vagotomy and antrectomy. Three abnormalities of motility associated with postoperative symptoms have been defined. If more than one abnormality was present in an individual there was an 80 per cent incidence of associated symptoms. Proximal gastric vagotomy produced significantly fewer abnormalities of gastro-duodenal motility than did truncal vagotomy and antrectomy.

Bilirubin↗