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Biomedical subjects

J C McMillan

Publications and source records attributed to J C McMillan.

At least 19 recordsLinked to original sources
PubMed2004

Coeliac disease-associated antibodies correlate with psoriasis activity.

BACKGROUND: Antigliadin antibodies (AGA) have been reported in patients with psoriasis. OBJECTIVES: To determine if AGA and other coeliac disease (CD)-associated antibodies correlate with clinical features and activity in patients with psoriasis. METHODS: Patients with psoriasis (n = 130) were investigated for serum IgG and IgA AGA, IgA antitransglutaminase antibody and IgA antiendomysial antibody. Disease characteristics and associated bowel and joint symptoms were determined. All patients were invited to undertake endoscopy with duodenal biopsy. RESULTS: A significantly higher proportion of patients with elevated CD-associated antibody levels was currently on or had previously required systemic immunosuppressants (methotrexate, ciclosporin or etretinate; P = 0.04) or psoralen plus ultraviolet A phototherapy (P = 0.03). One case of CD was diagnosed. CONCLUSIONS: The presence of CD-associated antibodies in psoriasis patients correlates with greater disease activity.

Adolescent↗
PubMed1991

Acromegaly and psoriasis.

A 56-year-old man with long-standing chronic plaque psoriasis was noted to be acromegalic. Investigations confirmed the presence of a large pituitary adenoma and following treatment of this by hypophysectomy his psoriasis cleared dramatically within 3 weeks.

Acromegaly↗
PubMed1990

Anaphylactic reactions to topical antibiotic combinations.

We describe two patients who developed anaphylaxis type reactions following the application of the topical antibiotic Polyfax (polymixin B and bacitracin). We draw attention to this potentially serious complication of topical antibiotic preparations and emphasize the need for careful history taking before prescribing such preparations.

Aged↗
PubMed1986

Functional differences between human cutaneous mast cells and basophils: a comparison of morphine-induced histamine release.

Intravenous administration of morphine sulfate often produces urticarial and hypotensive reactions associated with elevations in plasma histamine. The source of this histamine and mechanisms controlling its release are poorly understood. Previous studies of morphine-induced histamine release compared human leukocytes to rat peritoneal mast cells. The effects of morphine on human cutaneous mast cells has not been examined. We studied in vitro histamine release from human basophils and human skin preparations containing cutaneous mast cells to evaluate their relative contribution to the pharmacologic effects of morphine. Human skin mast cell preparations showed dose-dependent histamine release over a morphine concentration range of 1.5 X 10(-5) to 4.5 X 10(-3) M, with peak release occurring at 5 X 10(-4) M, with peak release occurring at 5 X 10(-4) M. Clinically, morphine sulfate is usually injected as a 1.5 X 10(-2) M solution. Histamine release was calcium dependent and equivalent to that obtained with 3 and 10 mM strontium. Morphologic examination revealed degranulation and exocytosis occurring in morphine-stimulated tissue but not in specimens exposed to buffer alone. Lactate dehydrogenase levels did not increase following morphine incubation, thus supporting a noncytolytic mechanism of histamine release. Basophils, in contrast, showed no significant histamine release from exposure to morphine up to 10(-2) M. Concanavalin A, as a positive control in these same preparations, produced a mean histamine release of 21.0%.(ABSTRACT TRUNCATED AT 250 WORDS)

Basophils↗
PubMed1986

Anaphylactic reaction during anaesthesia associated with positive intradermal skin test to fentanyl.

A 29 year-old female patient suffered vascular collapse which became apparent immediately after general anaesthesia. Resuscitation was prolonged and difficult, and complicated by the need for reoperation. Based on the time history, fentanyl was suspected as the causative agent. Fentanyl allergy was confirmed by skin testing one month later. The case is discussed, and the possible reasons for the delay in appearance of symptoms and signs are considered.

Adult↗
PubMed1985

Cyclic AMP-phosphodiesterase activity and histamine release in cord blood leukocyte preparations.

Atopic dermatitis, allergic rhinitis and asthma are a common group of diseases with a familial predisposition. At present there is no suitable predictive or diagnostic marker. Adults with atopic dermatitis or allergic respiratory disease have elevated mononuclear leukocyte cAMP-phosphodiesterase activity. This activity correlates closely with histamine release from basophils. We investigated newborn leukocyte phosphodiesterase activity and histamine release in umbilical cord blood. Phosphodiesterase activity was significantly elevated in cord blood leukocytes of 81 children with a positive history of atopy in first degree relatives, compared to 33 children with a negative history (p less than 0.025). In contrast to adults there was no correlation between phosphodiesterase activity and histamine release. Our studies suggest that elevated phosphodiesterase activity is a primary, genetically linked defect. Fetal basophils would appear to possess cytophilic IgE since they are capable of immunologically stimulated histamine release even without passive, in vitro IgE sensitization. In addition, there are functional differences between adult and cord blood basophils. Longitudinal studies may determine if elevated phosphodiesterase is predictive of atopic states.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1974

Average uncertainty as a determinant of observing behavior.

After discrimination training on a multiple variable-interval extinction schedule of food reinforcement, pigeons were placed on the uncued or mixed version of the same schedule and allowed to make an optional "observing response" that converted the uncued schedule to the corresponding cued schedule by providing a 20-sec exposure to the appropriate discriminative stimulus. The schedule consisted of one hundred 40-sec components, and the probability that any one of them would be a variable-interval component was systematically varied between 0.00 and 1.00. The results showed that the amount of observing behavior was an inverted "U" function of the probability of the variable-interval component. Few observing responses occurred at probabilities of 0.00 or 1.00, and maximum responding occurred at a value less than 0.50.

Journal Article↗
PubMed1971

Percentage reinforcement of fixed-ratio and variable-interval performances.

Twenty to seventy per cent of the reinforcements scheduled for pigeons' fixed-ratio 80 performances were replaced by a 4-sec timeout. Pauses after reinforced ratios were unchanged at 80% reinforcement, but were lengthened at lower reinforcement percentages. Pauses after nonreinforced ratios were shorter than post-reinforcement pauses. When 50% of the reinforcements arranged by a variable-interval 60-sec schedule were replaced by a 4-sec timeout, pauses after reinforcement omission increased. Both frustrative nonreward and reinforcement aftereffects notions can explain the fixed-ratio results; neither easily explains the variable-interval data.

Journal Article↗
PubMedDate not supplied

Varying temporal placement during CS of an added stimulus correlated with non-delivery of UCS.

This experiment extends Pavlov's method of contrasts for training a stimulus discrimination to the case of the cardiac conditional response in the rhesus monkey. It explores the parameter of temporal placement of an additional stimulus ("CS2") within a 10-sec CS (or "CS1"), with the appearance of the former stimulus on any trial signalling the absence of UCS (electric shock) on that trial. This experimental paradigm is a parallel to that of the "intruded stimulus" studies in operant conditioning. In both cases, several ways of describing the function of the added stimulus are possible, but all seem reducible to the same operational terms. Data were taken in the present study with respect to the form and latency of the cardiac rate changes produced by intrusion of CS2 (light), across a range of placements varying from simultaneity with CS1 (a different light) onset to two sec before UCS would have been delivered. The control of CS2 over the cardiac rate CR was occasionally exhibited with a latency as short as three beats after stimulus onset. The order of CS2 temporal placements to which a subject was exposed was a factor in determining the form of the conditioned cardiac rate response to CS1.

Animals↗