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Biomedical subjects

R J Stevenson

Publications and source records attributed to R J Stevenson.

At least 37 records · Page 2Linked to original sources
PubMed1995

Luminal narrowing after autoanastomosis and intraluminal slough in intussusception: a case report and historical review.

Historical literature notes slough of an intussusceptum with autoanastomosis as an infrequent natural course of childhood intussusception resulting in survival. The case of an 8-year-old boy with abdominal pain several years after an apparent untreated childhood intussusception is presented. Cecal resection shows evidence of previously sloughed intussusceptum with cicatral luminal narrowing at site of autoanastomosis. This case illustrates a rare cause of abdominal pain and partial intestinal obstruction in childhood.

Child↗
PubMed1995

Effects of oral chemical irritation on tastes and flavors in frequent and infrequent users of chili.

The studies reported here addressed the question of whether the pungent principle in chilies, capsaicin, suppresses taste and flavor intensity. Over a period of several minutes, groups of frequent and infrequent eaters of chili repeatedly rated the taste and flavor intensities of sweet and sour solutions that also contained either orange or vanilla flavor, and capsaicin at 0, 2, 4, and 16 ppm. As well as the intensity of the qualities while in the mouth, measures of the number of rating periods for the intensity to dissipate to zero, and the summed total intensity were also derived. Infrequent chili users rated the capsaicin burn as more intense than did the frequent users. With few exceptions, and for groups, sweetness was suppressed by the presence of capsaicin. By contrast, sourness was unaffected by capsaicin. Flavor intensities also showed suppression by capsaicin. High correlations between ratings of sweetness and flavor were found, suggesting that perceptual confusion between the two qualities may have been responsible for the flavor suppression. A second experiment examined the effects of capsaicin on ratings of strawberry flavor alone. This study produced little evidence of flavor suppression by capsaicin. These results are discussed in terms of an attentional model of capsaicin's effects.

Administration, Oral↗
PubMed1995

Does exposure enhance liking for the chilli burn?

It has been suggested that merely being exposed to a novel stimulus can enhance liking for it. Two experiments explored this hypothesis in relation to the development of liking for the chilli burn in a two-course meal. In the first experiment there was a linear increase in rated liking for the burning sensation produced by 2.5 and 5.0 ppm capsaicin between the first and the fifth exposure to an experimental meal, whereas no significant change was seen for the vehicle food or the preceding non-chilli flavoured food. In the second experiment a similar linear trend was observed with the 5.0 ppm stimulus. However, liking and sensory ratings for an ascending capsaicin concentration series in a tomato juice vehicle tested before and after the exposure period were unaffected by any change in liking for the chilli burn in food. This experiment also suggested that increases in liking were not dependent on initial unfamiliarity with the chilli burn or on changes in rated burn intensity or arousal. Potential explanations for the observed effects are considered.

Adult↗
PubMed1992

The predictive value of head ultrasound in the ECMO candidate.

Cranial ultrasound (US) examination is the screening technique of choice for assessing preexisting neurological damage in potential neonatal extracorporeal membrane oxygenation (ECMO) candidates. Currently, US evidence of intracranial hemorrhage greater than grade I in severity is a contraindication to ECMO at this ECMO center. In the current study, radiological findings were reviewed in 129 consecutive neonatal ECMO cases in an attempt to identify which pre-ECMO US findings were associated with the development of subsequent intracranial complications while on ECMO. Pre-ECMO head US, post-ECMO head US, and head computed tomography (CT) scans were reviewed retrospectively by one radiology team. Ventricular, parenchymal, and extraaxial fluid abnormalities were recorded for each case. Pre-ECMO US findings were then correlated with the subsequent development of significant intracranial radiological abnormalities noted on post-ECMO studies as well as with clinical data regarding ECMO course and outcome. Results showed that infants with evidence of severe edema or periventricular leukomalacia on pre-ECMO imaging had a 63% incidence of subsequent major intracranial complications. This represents a significantly higher risk than in candidates with a normal examination or evidence of grade I intracranial hemorrhage, subependymal cysts, or mild edema. These results suggest that infants with sonographic evidence of ischemic or anoxic damage on pre-ECMO US are at high risk for the development of significant intracranial complications if ECMO therapy is instituted.

Brain↗
PubMed1992

Oxidation of phosphatidylcholine membranes by singlet oxygen generated in the gas phase.

Singlet-oxygen (1O2) was generated in the gas phase by heterogeneous photosensitization and bubbled into suspensions of phosphatidylcholine (PC) liposomes. Lipid peroxidation and membrane lysis were observed, and were dependent on the 1O2 concentration and the degree of unsaturation of the liposome. An analysis based on large target diffusion theory indicates that approximately 5000, 2800, and 1600 interactions were required for the lysis of large dioleoylPC, dilinoleoylPC and dilinolenoylPC liposomes, respectively.

Kinetics↗
PubMed1990

The use of heuristic strategies in the interpretation of pronouns.

The aim of the two experiments reported here was to distinguish between two heuristic strategies that have been proposed to account for the assignment of pronouns: the subject assignment strategy and the parallel function strategy. According to the subject assignment strategy, a pronoun is assigned to a preceding subject noun phrase, whereas according to the parallel function strategy, a pronoun is assigned to a previous noun phrase in the same grammatical position as the pronoun. These two strategies were tested by examining the interpretation of single object pronouns, first in a reading task and second in an assignment task. In both experiments, there was a strong preference for assigning an object pronoun to the preceding subject noun phrase, thus supporting the subject assignment strategy. However, this was only the case for pronouns that were linguistically ambiguous. When assignment was constrained by gender, there was no effect of either strategy. It is suggested that heuristic strategies are only used in the absence of other strong cues to assignment.

Attention↗
PubMed1990

Reference in single sentences and in texts.

This study investigated the comprehension and production of reference terms in both sentences (Experiments 1 and 2) and texts (Experiments 3 and 4) using a sentence completion task. In Experiments 1 and 2, the use of a sentence-level strategy (subject assignment) was investigated. In Experiments 3 and 4, the use of a text-level strategy (topic assignment) was also investigated. There was a clear preference for continuing the sentences by referring to the subjects of the sentences regardless of the availability of gender cues, in both single sentences and in texts. There was also an influence of the topic of each text on both the choice of referent and the type of reference term used. However, the choice of reference term was affected by the number of potential antecedents in the preceding text. Overall, the results suggest that the sentence subject is a salient item in working memory. This salience is increased if the sentence subject is also the textual topic. In addition, it appears that the presence of a pronoun in a text triggers a specific strategy to assign the pronoun to the (salient) sentence subject.

Adolescent↗
PubMed1990

Percutaneous transperineal pouch localization in low imperforate anus: a new approach.

Patients who have an imperforate anus with associated infralevator, or low rectal pouch, are candidates for a perineal anoplasty. However, in the absence of a perineal fistula, intraoperative localization and isolation of the rectal pouch can be difficult. We have developed a technique to facilitate isolation and dissection of the rectal pouch for perineal anoplasty in patients with a low imperforate anus who do not have a perineal fistula present. Pouch localization is carried out preoperatively by fluoroscopic percutaneous transperineal placement of a Fogarty embolectomy catheter through the center of the anal wink. We have used this technique successfully in four consecutive patients who had a low imperforate anus, in the absence of a perineal fistula, with the pouches 1.0 to 1.5 cm from the perineum. Results have been excellent, and the dissection of the rectal pouch was facilitated greatly by the presence of the inflated Fogarty balloon.

Anal Canal↗
PubMed1990

High apical insertion of the right diaphragm in an infant with right-sided Bochdalek diaphragmatic hernia.

We report the case of a newborn full-term infant who presented to our service on the first day of life with a right-sided Bochdalek congenital diaphragmatic hernia associated with a high apical insertion of the right hemidiaphragm at the level of the second rib. This resulted in incarceration of the left lobe of the liver within the right hemithorax, but minimal pulmonary hypoplasia. A search of the literature failed to show a previous report of this variant of a duplication of the diaphragm in conjunction with a congenital diaphragmatic hernia. The approach taken for diaphragmatic reconstruction and closure of the defect is described.

Abnormalities, Multiple↗
PubMed1985

Abdominal pain unrelated to trauma.

This article reviews the more common causes of abdominal pain in children. It is divided into three sections to emphasize differential diagnosis. For some problems responsible for abdominal pain surgery is essential, for some surgery may not be initially required but may be unavoidable, and for others the condition is purely medical and surgery should be avoided. Armed with a complete differential diagnosis, the general surgical resident may avoid many pitfalls.

Abdomen↗
PubMed1985

Non-neonatal intestinal obstruction in children.

This article is intended to update the general surgeon on and inform the general surgical resident of new concepts in pediatric bowel obstruction. Specifically, newer diagnostic modalities are discussed, and more emphasis is directed toward diagnoses that the general surgeon is more apt to encounter.

Child, Preschool↗
PubMed1985

Gastrointestinal bleeding in children.

This article provides an update on the advances in technologic investigations of upper gastrointestinal bleeding. Lesions responsible for bleeding are discussed from proximal to distal.

Age Factors↗
PubMed1985

Abdominal masses.

The more common abdominal masses of the pediatric age group are discussed along with current thoughts regarding preoperative imaging modalities. A careful physical examination is indispensable, and masses should be evaluated with consideration given to mobility, location, consistency, contour, and site. A rectal examination is essential. The more unusual clinical presentations are discussed in appropriate sections.

Abdomen↗
PubMed1984

Selective memory effects in agoraphobic patients.

Two experiments tested the view that agoraphobic patients would show superior recall for phobic-related material relative to neutral material. In Expt 1, subjects were required to recall a series of five passages; three contained potentially phobic information and two contained neutral information. The results showed that phobic patients recalled more propositions from the phobic passages than did controls. In Expt 2, subjects completed four study-test trials with a list of 20 words: 10 phobic words and 10 neutral words. The results showed that the patients recalled more phobic than neutral words while the reverse was the case for controls. The results are discussed in terms of the cognitive organization of phobic patients and are related to Beck & Rush's proposal that phobics have a cognitive organization of situations labelled as dangerous. The possible sources of these selective memory effects are also considered.

Adult↗