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Biomedical subjects

R J Stewart

Publications and source records attributed to R J Stewart.

At least 91 records · Page 5Linked to original sources
PubMed1989

Mucinous cystadenocarcinoma of the pancreas: diagnosis by fine-needle aspiration cytology.

Two cases of mucinous cystadenocarcinoma of the pancreas are described in which the diagnosis was made from the material obtained by a computed tomography-guided fine-needle aspiration cytology examination. It is strongly felt that aspiration cytology, when performed under imaging guidance, is sensitive and specific in the diagnosis of mucinous cystadenocarcinoma and allows for a relatively simple yet confident diagnostic interpretation of this uncommon pancreatic tumour.

Aged↗
PubMed1989

Regional hyperthermia for advanced tumors: a clinical study of 353 patients.

A Phase I study using deep regional hyperthermia (HT) with an annular phased array was conducted in 14 U.S. medical centers from 1980 through 1986. There were 353 patients whose average age was 57 years. All patients had advanced recurrent or persistent tumors. Prior frequently complex, multimodality anti-cancer therapy was received by 71% of the patients. Gastrointestinal adenocarcinoma was present in 146 (41%) patients, genitourinary tumors in 86 (24%), soft tissue sarcomas in 46 (13%), malignant melanoma in 21 (6%) and 15% had other tumors. The sites treated included: pelvis 55%, abdomen 21%, liver 14%, thorax 6%, and other sites 3%. All patients received deep regional HT with an average frequency of 55 MHz. A total of 1412 HT treatments was administered to these 353 patients with an aim to increase the temperature in the volume of interest to greater than 42 degrees C for greater than or equal to 30 minutes. Thermal dose (TD in equivalent minutes at 42.5 degrees C) was less than 50 in 104 (29%), greater than or equal to 50 less than 100 in 30 (11%), greater than or equal to 100 in 26 (7%), and greater than 200 in 34 (10%). The remaining 150 (42%) patients had TD = 0. In addition to HT, 260 (74%) received radiotherapy (RT). RT was given at 180 or 200 cGy daily with an average total dose of 33.4 Gy. A total of 42 (12%) patients were given chemotherapy (CT) with HT, and 15 (4%) CT + HT + RT/HT alone was given to 47 (13%) patients. Complete response (CR) was obtained in 35 (10%) and partial response (PR) in 59 (17%) patients. CR was 12% in patients who received RT, vs 2% in those who did not receive it, p = 0.003. Radiation dose was an important factor influencing response, p less than 0.001. Thermal dose was not an important parameter influencing tumor response. A duration of CR ranged from 4 to 73 weeks with an average duration of 31 weeks and the median duration of 28 weeks. The overall 2-year survival was 13% with the median survival of 42 weeks. Patients with CR and PR had a 2 year survival of 41%, and a median survival of 71 weeks. This compared with 8% 2-year survival and 24 weeks median survival in patients who did not have CR or PR, p less than 0.001. Of the patients presenting with significant pain, 62% had complete or partial pain relief.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1988

Fine catheter peritoneal cytology for the acute abdomen: a randomized, controlled trial.

A randomized, controlled clinical trial, of sequential design, was undertaken to determine whether fine catheter aspiration cytology of the peritoneal cavity, using the percentage of neutrophils in the sample as the main test marker, reduces errors about urgent laparotomy in patients admitted to a surgical unit with acute abdominal pain. One hundred and forty-four patients with acute abdominal pain were studied. Of these, 26 were excluded because the test was unlikely to be useful and 20 did not consent. Conventional clinical assessment was undertaken and then the subjects were randomly allocated to have a peritoneal cytology test or not. After the test result was made available, the surgeon(s) decided whether to operate or continue conservative treatment. The correct decision was later ascertained by a blinded clinical referee. With the entry of the 98th patient the difference between the groups achieved the 5% significance level. The groups were well-matched in regard to demographic and other variables. The decision about urgent laparotomy was incorrect in only 8.2% of the test patients, compared with 28.6% of the others. It is concluded that fine catheter aspiration cytology of the peritoneal cavity is likely to reduce the numbers of unnecessary or delayed laparotomies when used in most patients admitted with acute abdominal pain.

Abdomen, Acute↗
PubMed1988

Choledochal cyst: case reports and current concepts.

Choledochal cyst is an unusual but serious condition which most commonly affects Oriental people. Recent experience of three patients with this condition in whom diagnosis was made by ultrasound examination is reported. Cholangiography (ERCP or PTC) was performed in two of the cases to define the anatomy. All three cases were successfully managed by cyst excision and biliary reconstruction by Roux-en-Y hepaticojejunostomy. The rationale for and importance of cyst excision are discussed.

Adolescent↗
PubMed1987

Effects of extinction, pimozide, SCH 23390, and metoclopramide on food-rewarded operant responding of rats.

The similarity in the pattern of responding produced by extinction and dopamine (DA) receptor blockers has led to the suggestion that DA neurons may participate in the usual effects of reward on behaviour. The purpose of the present study was to evaluate the effect of receptor-subtype specific DA antagonists on food-rewarded operant responding. Rats were trained to lever press for food on a variable interval 30-s schedule. They then received one of the following treatments prior to testing on the next 5 days: saline, nonreinforcement, the DA receptor blocker pimozide (0.5 or 1.0 mg/kg), the D1 receptor blocker SCH 23390 (0.01, 0.05, 0.1 mg/kg), and the D2 receptor blocker metoclopramide (1.0, 5.0, 10.0 mg/kg). Nonreinforcement resulted in both intra- and intersession declines in responding. The drugs produced dose-dependent decreases in overall responding. Additionally, both doses of pimozide and the higher doses of SCH 23390 and metoclopramide altered intrasession patterns of responding when compared to saline, with their greatest effect being in the latter portion of the session. Intersession declines were seen with the highest doses of SCH 23390 and metoclopramide and control studies showed that these declines could not be attributed to a buildup of the drug with repeated dosing. It was concluded that both D1 and D2 receptors participate in the control of behaviour by reward.

Animals↗
PubMed1987

Circling behavior following unilateral microinjections of cocaine into the medial prefrontal cortex: dopaminergic or local anesthetic effect?

Dopaminergic projections to the medial prefrontal cortex have been implicated in cocaine reinforcement; therefore, it was of interest to examine the locomotor effects of acute administration of cocaine to this area. Circling behavior was assessed following injections of 1.0 microliter of cocaine in doses of 0 (0.9% saline), 25, 50, and 100 micrograms/microliters into the medial prefrontal cortex of rats prepared with chronic unilateral guide cannulae. Animals were scored during four 5 min intervals of a 60 min test session that began with the central injection and placement in a flat circular arena. Cocaine was found to produce dose-dependent contraversive circling, an effect previously seen with the dopamine (DA) agonists LY 14 1865 and (+)-amphetamine, suggesting a unilateral stimulant effect. However, since cocaine has potent local anesthetic properties that have been reported to produce behavioral effects and also to inhibit the reuptake of norepinephrine and 5-HT, it was important to demonstrate that the directional bias was a dopaminergic effect. Intra-frontocortical microinjections of the local anesthetic procaine (10, 100, and 1000 micrograms in 0.5 microliter) did not induce circling. Sulpiride (0.001-10.0 micrograms in 0.5 microliter), a DA antagonist specific for the D-2 receptors, produced ipsiversive circling in a dose-dependent manner in rats treated with (+)-amphetamine (1.5 mg/kg, i.p.). In addition, sulpiride (1.0 micrograms in 0.5 microliter) blocked the circling behavior induced by cocaine (50 micrograms in 0.5 microliter) when administered into the medial prefrontal cortex 15 min prior to the cocaine injection. These results provide further evidence for an excitatory influence of mesocortical DA on motor control.

Anesthesia, Local↗
PubMed1986

The presentation and management of presacral tumours.

Twenty cases of presacral tumours are presented, nine males and eleven females being affected. Malignancy occurred in 50 per cent of adults and was commoner in men than in women. Diagnosis depends on a careful rectal examination. Computerized axial tomography is the single most useful investigation; however, should it not be available, plain X-rays and ultrasonography give considerable information. For lesions less than 10 cm in size a local parasacral approach is often feasible but for larger lesions an abdominal approach or combined approach should be considered.

Adolescent↗
PubMed1986

Early detection of extravascular lung water in an inhalation injury animal model.

A rabbit inhalation injury model using a dual tracer radioactive isotope technique (Rowland et al., 1986), has been utilized with small- and medium-sized molecular weight tracers. There is oedema formation at 2 h after smoke inhalation or fluid resuscitation and especially with the combination of inhalation injury and fluid resuscitation [corrected]. This oedema appears to have decreased by 24 h post-injury. There does not appear to be any difference between the small- and medium-sized tracers in the transit times of tracer in the lung vascular compartment. The increases in extravascular water volume have been confirmed by gravimetric analyses of the lungs. Thus the pulmonary oedema in the rabbit animal model is detectable within 2 h post-injury, with a return towards normal values some time within 24 h if fluid challenged for short periods. Fluid resuscitation exacerbates the amount of oedema that developed. The onset of pulmonary oedema may therefore be earlier than previously seen clinically, and fluid resuscitation modifications may be of benefit in smoke inhalation injury.

Animals↗
PubMed1985

Patients with acute abdominal pain: white cell and neutrophil counts as predictors of the surgical acute abdomen.

Two hundred and fifty-two patients with acute abdominal pain were admitted to Wellington Hospital during three consecutive months in 1982. The prevalence of the surgical acute abdomen in these patients was 35%. There was no significant difference in performance between the peripheral blood white cell count (WCC) and neutrophil count (NC) when used as diagnostic tests of surgical acute abdomen. Neither test is sufficiently sensitive or specific to be a good predictor of surgical acute abdomen. It is recommended that the WCC be used sparingly and interpreted as a continuously distributed rather than dichotomous diagnostic test. There is no advantage in using the NC.

Abdomen, Acute↗