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Biomedical subjects

P Collins

Publications and source records attributed to P Collins.

At least 253 records · Page 14Linked to original sources
PubMed1991

Comparison of rabbit coronary arterial relaxation induced by acetylcholine and lemakalim: activation of ATP sensitive potassium channels.

STUDY OBJECTIVE: The purpose was to assess the role of ATP sensitive potassium channels (KATP) in endothelium dependent vasodilatation induced by acetylcholine, or endothelium independent vasodilatation induced by lemakalim in rabbit coronary arteries. DESIGN: The effect of glibenclamide, a specific inhibitor of KATP, on coronary artery relaxation induced by acetylcholine or lemakalim was investigated. The relaxing effectiveness of acetylcholine and lemakalim on coronary arteries precontracted with KCl (K+) or prostaglandin F2 alpha (PGF2 alpha) was compared. EXPERIMENTAL MATERIALS: Left epicardial coronary arteries from male New Zealand white rabbits (2.5-3.0 kg), killed by an overdose of pentobarbitone, were dissected free of connective tissue. Rings suspended in organ baths for the measurement of isometric tension. MEASUREMENTS AND MAIN RESULTS: K+ (30 mmol.litre-1) and PGF2 alpha (3 mumols.litre-1) caused comparable contraction (p greater than 0.05) in endothelium intact or endothelium denuded coronary arterial rings. Acetylcholine induced relaxation was greater in endothelium intact rings precontracted with PGF2 alpha than with K+ and was abolished by the removal of endothelium. Relaxations induced by acetylcholine (0.1 and 0.3 mumol.litre-1) were reduced from 82(SEM 2.7)% and 93(2.8)% to 71(2.4)% and 82(2.7)% (p less than 0.05), and to 63(3.2)% and 79(4.5)% (p less than 0.05 or less than 0.01) by glibenclamide (3 and 10 mumols.litre-1) respectively in PGF2 alpha precontracted rings; and also attenuated (p less than 0.05 or less than 0.01) in K+ precontracted rings. Lemakalim induced relaxation was greater in endothelium denuded rings precontracted with PGF2 alpha than with K+, and was markedly reduced by glibenclamide (p less than 0.01). CONCLUSIONS: These results suggest that activation of KATP may partially be involved in endothelium dependent relaxation induced by acetylcholine in rabbit coronary arteries. Lemakalim-induced endothelium independent relaxation results mainly from activation of KATP.

Acetylcholine↗
PubMed1991

Acute febrile neutrophilic dermatosis in childhood (Sweet's syndrome).

We report a case of Sweet's syndrome in childhood. Our patients suffered from repeated fevers, chest infections and had characteristic erythematous plaques. The severity of his illness increased with age and warranted oral steroid treatment. We review 16 cases reported to date in the literature and comment on the management and prognosis of the disease in childhood.

Fever↗
PubMed1991

Bath-water delivery of 8-methoxypsoralen therapy for psoriasis.

Twenty-one patients with chronic plaque psoriasis were treated with bath 8-methoxypsoralen (8-MOP) and ultraviolet A (UVA). Clearing was achieved in sixty per cent of patients which was less than would be expected with oral 8-MOP. The treatment was well tolerated and was preferred by those who had previously been treated with oral psoralen. The cumulative dose of UVA was only one-fifth that expected with oral 8-MOP.

Adult↗
PubMed1991

Cryotherapy for lentigo maligna.

Eleven patients, 10 with lentigo maligna (LM) and one with lentigo maligna melanoma (LMM), were treated with cryotherapy. The symptoms cleared in all patients except one with LM. There were recurrences in four patients and three cleared with further treatment.

Aged↗
PubMed1991

Hypertriglyceridaemia and its influence on low density lipoprotein regulation of cellular cholesterol synthesis: a comparison between hypertriglyceridaemic diabetic and non-diabetic patients.

The present investigation was undertaken to examine the relationship between serum triglyceride and composition of lipoprotein. Six groups of patients were examined, three with Type 2 (non-insulin-dependent) diabetes and three without diabetes. The groups were further categorized on the basis of their serum cholesterol and triglyceride levels into normocholesterolaemic (serum cholesterol less than 6.5 mmol l-1) and hypercholesterolaemic (serum cholesterol greater than 6.5 mmol l-1) with and without hypertriglyceridaemia (serum triglyceride greater than or less than 3.5 mmol l-1). Low density lipoprotein (LDL) composition was determined and regulation of cholesterol synthesis by LDL was assessed by measuring its effect on [14C]-acetate incorporation into mononuclear leucocyte cholesterol. LDL from the hypercholesterolaemic diabetic patients had a significantly higher esterified cholesterol content when the patients were normotriglyceridaemic (1.14 +/- 0.04 vs 0.76 +/- 0.04 g g-1; p less than 0.01). The ability of LDL to suppress cholesterol synthesis (percent inhibition) was significantly less using LDL from the normocholesterolaemic diabetic patients or hypercholesterolaemic non-diabetic or diabetic patients compared with LDL from the normocholesterolaemic non-diabetic control subjects (47.4 +/- 3.9%, 39.1 +/- 5.1% and 35.2 +/- 4.1% vs 59.5 +/- 1.2%, p less than 0.01). However, hypertriglyceridaemia had no effect on LDL suppression of cholesterol synthesis. We conclude that hypertriglyceridaemia alters LDL composition but the alteration is not associated with the ability of LDL to regulate cholesterol synthesis.

Acetates↗
PubMed1991

Endothelium-independent relaxation of rabbit coronary artery by 17 beta-oestradiol in vitro.

1. We assessed the relaxant effect of 17 beta-oestradiol (10(-7), 10(-6) and 10(-5) M) on rabbit isolated coronary arteries precontracted with prostaglandin F2 alpha (3 x 10(-6) M), high extracellular potassium (30 mM) and Bay K 8644 (10(-6) M) plus high extracellular potassium (15 mM) by measuring isometric tension. 17 beta-Oestradiol (10(-6) and 10(-5) M) induced significant relaxation in coronary arteries from male and female rabbits. No differences were seen between arteries with or without endothelium. There were also no differences between coronary arteries isolated from male and female rabbits. 2. Inhibitors of endothelium-derived relaxing factor and vasodilator prostanoids, namely, reduced haemoglobin, N omega-nitro-L-arginine methyl ester and indomethacin, did not affect the relaxation induced by 17 beta-oestradiol in endothelium-intact coronary arteries. 3. Methylene blue, an inhibitor of guanylate cyclase, did not affect the coronary artery relaxation induced by 17 beta-oestradiol. 4. The calcium concentration-dependent contraction curve in potassium-depolarization medium was shifted to the right by 17 beta-oestradiol (10(-6) and 10(-5) M) in the rabbit coronary artery and rat aorta. The -log EC50s of calcium in control and after incubation with 17 beta-oestradiol (10(-6) and 10(-5) M) were 3.7 +/- 0.09, 3.1 +/- 0.10 and 2.8 +/- 0.08 respectively in rabbit coronary arteries and 3.8 +/- 0.11, 3.3 +/- 0.14 and 2.9 +/- 0.15 in rat aorta. 5. The results indicate that 17 beta-oestradiol induces rabbit coronary artery relaxation by an endothelium-independent mechanism in vitro. A calcium antagonistic property may be involved in the mechanism of rabbit coronary arterial relaxation by 17beta-oestradiol.

Animals↗
PubMed1991

Poikiloderma congenitale: case report and review of the literature.

Since birth an 8-year-old girl had a rash on both cheeks, consistent clinically and histologically with poikiloderma. She also had visual impairment to the extent of light perception only, due to microthalmia and dense scleralization of the corneas. These features were considered consistent with a diagnosis of Rothmund-Thomson syndrome.

Cataract↗
PubMed1991

Progression to type I diabetes in autoimmune endocrine patients with islet cell antibodies.

In an 11-yr screening program carried out on serum samples sent to an autoimmune serology laboratory, 158 patients with clinical or subclinical autoimmune endocrine manifestations and islet cell antibodies (ICAs) in the absence of overt diabetes were identified and followed for the development of insulin-dependent (type I) diabetes. Twenty-two (13.9%) developed type I diabetes in a follow-up of up to 12 yr (mean +/- SE 4.8 +/- 3.2 yr). The probability of being free of type I diabetes was 69.8% at 10 yr after the first detection of ICAs. Progression to disease was influenced by 1) the amount of ICAs represented by high titers (63% of those with ICAs greater than or equal to 20 Juvenile Diabetes Foundation units being free of type I diabetes at 10 yr), ICA persistency (59% being free of type I diabetes; P less than 0.02 vs. nonpersistent ICA), and complement-fixing (CF)-ICAs (63% being free of type I diabetes; P less than 0.05 vs. non-CF-ICA); 2) the coexistence of insulin autoantibodies (IAAs) (25% being free of type I diabetes; P less than 0.005 vs. IAA-); and 3) a positive family history (1st-degree relative) for type I diabetes (32% being free of type I diabetes; P less than 0.005 vs. no family history). There was a trend for diabetes to develop earlier in males of a younger age. No relationships were found with the number, type, or clinical expression of the associated autoimmunities or with a family history of such disorders.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Interaction between sound and gentamicin: immediate threshold and stereociliary changes.

Our aim was to determine whether the immediate effects of a just-damaging sound exposure (8 kHz at 116 dB SPL for 1 h) might be potentiated by a single sub-ototoxic dose of gentamicin (50 mg kg-1). Auditory brainstem responses in pigmented guinea pigs were measured before and after treatment and used to calculate threshold shift (TS). Histological disturbances to sensory hair cells were assessed by scanning electron microscopy. All experimental ears excepting the gentamicin only group showed TS and histological changes. The largest TSs occurred at half an octave above the exposure frequency, and were greatest in the gentamicin + sound (G + S) group. First row outer hair cells showed most histological disturbances, followed by inner hair cells. The severest histological damage occurred at the exposure frequency and basally from it, the G + S group being most affected. Generally, there was good correlation between the severity of TS and histological damage. Results from both analyses indicated greater changes with gentamicin present.

Acoustic Stimulation↗
PubMed1991

Erythema induratum (Bazin's disease).

Four patients with erythema induratum (EI) have been diagnosed at the Dermatology Department within the past two years. All four patients had a history of recurrent painful nodules on their calves for at least three years before diagnosis. Three of the patients, all with positive Mantoux reaction to tuberculin skin tests, had neither a personal or family history of tuberculosis. The other patient who had a six year history of recurrent painful leg nodules developed a tuberculous breast abscess. There was a dramatic response to anti-tuberculous chemotherapy in all four patients but one subsequently had recurrent nodules which spontaneously subsided without further chemotherapy.

Aged↗
PubMed1991

Excision of an arteriovenous malformation.

Arteriovenous malformations (AVM) are congenital vascular lesions consisting of direct communications between associated arteries and veins without an interposed capillary bed. These vessels are typically thin walled, lack an internal elastic intima, and are quite prone to hemorrhage. A previously healthy 17-year-old woman presented with severe, persistent headache. After undergoing computed tomography (CT scan) and magnetic resonance imaging (MRI), the patient was diagnosed as having an intracranial arteriovenous malformation. The anesthetic management of this patient included induction with sodium thiopental and sufentanil. General anesthesia was maintained with isoflurane in oxygen and a continuous intravenous infusion of sufentanil. Neuromuscular blockade was established prior to endotracheal intubation with vecuronium and maintained with a combination of metocurine and pancuronium. The sufentanil infusion was discontinued when vascular isolation of the AVM had been accomplished. The isoflurane was discontinued 30 minutes prior to skin closure. Neuromuscular blockade was then antagonized with neostigmine and glycopyrrolate. Spontaneous ventilation resumed when the patient's arterial carbon dioxide tension (PaCO2) was allowed to normalize. The hemodynamic character of this anesthetic course was smooth and uneventful. The patient emerged from anesthesia comfortable and lucid and experienced no perioperative anesthetic complications.

Adolescent↗
PubMed1990

Hypothesis: inhibition of endothelium-derived relaxing factor by haemoglobin in the pathogenesis of pre-eclampsia.

Although the aetiology of pre-eclampsia is unknown, haemodynamic studies suggest that many of the clinical findings may be explained by a generalised vasoconstrictive disorder and abnormal endothelial cell function. Vasoconstriction may be attributed to the increased concentrations of haemoglobin found in pre-eclampsia compared with normal pregnancy. Free haemoglobin may be derived from haemolysis and placental haemorrhage and, at concentrations known to be present in pre-eclampsia, vasodilatation mediated by endothelium-derived relaxing factor is inhibited. Infusion of oxyhaemoglobin into human coronary arteries inhibits acetylcholine-induced vasodilatation. We suggest that an increased free haemoglobin concentration is the cause of vasoconstriction in pre-eclampsia.

Coronary Vessels↗
PubMed1990

Agonist-induced production of 1,2-diacylglycerol and phosphatidic acid in intact resistance arteries. Evidence that accumulation of diacylglycerol is not a prerequisite for contraction.

The production of total amounts of 1,2-diacylglycerol as well as those specifically derived from inositol lipid hydrolysis was studied in intact rat resistance arteries stimulated with either noradrenaline, vasopressin, or angiotensin II at 20 s when the onset of contraction would be nearing its maximum, and at 5 min during the sustained phase of contraction. Total amounts of 1,2-diacylglycerol were not altered by any agonist at 20 s, or at 5 min. However, arachidonate-containing species of 1,2-diacylglycerol were differentially influenced being increased at 5 min by noradrenaline, and decreased at 20 s and 5 min by vasopressin. Only angiotensin II produced substantial increases in this class of 1,2-diacylglycerol at both time points. In order to investigate the fate of this second messenger total and inositol lipid derived phosphatidic acids were then measured at both 20 s and 5 min. Noradrenaline induced a rise in both total and arachidonate-containing phosphatidic acid at both times as did vasopressin. Only small increases were induced by angiotensin II at 20 s. These data demonstrate that the accumulation of 1,2-diacylglycerol generated from inositol lipid breakdown is only observed with activation by angiotensin II. Other agonists produced phosphatidic acids with time and the rate of generation of these lipids is agonist-specific. Thus phosphatidic acid may play a more prominent role during the sustained phase of contraction than previously anticipated.

Angiotensin II↗
PubMed1990

Cellular cholesterol metabolism in mitogen-stimulated lymphocytes--requirement for de novo synthesis.

The relationship between cholesterol synthesis and uptake in proliferating lymphocytes has been examined. [14C]Acetate incorporation into lymphocytes cultured under lipoprotein-deficient conditions increased initially in response to mitogen, decreased after 24 h, and increased rapidly between 72 and 96 h. Addition of LDL (10 micrograms/ml) to the culture during the 'trough' period caused [14C]acetate incorporation to return rapidly to baseline, while at peak periods LDL suppression of cholesterol synthesis was minimal. Lymphocytes cultured in the presence of the HMG-CoA reductase inhibitor, mevinolin, exhibited a time-dependent increase in their capacity to incorporate [14C]acetate into cholesterol, evident when mevinolin was removed by washing prior to assay. PHA enhanced 125I-labelled LDL receptor-mediated binding by lymphocytes cultured in lipoprotein-deficient medium over a 4 day period and mevinolin augmented the effect. [3H]Thymidine incorporation into mitogen-stimulated lipoprotein-deficient cultures was inhibited up to 75% by mevinolin (1 mumol/l). LDL (2.5-10 micrograms/ml) substantially reversed this inhibition in 72 h cultures, but only partially overcame inhibition in cells cultured for 96 h. Results suggest that endogenous cholesterol synthesis may be obligatory for lymphocyte proliferation after the initial round of cell division.

Acetates↗
PubMed1990

Abnormal involuntary movements and chronic schizophrenic disorders.

We hypothesized that chronic schizophrenic patients with abnormal involuntary movements would exhibit specific psychopathological, neurological, and cognitive disturbances at a more severe level than those free of such movements. Twenty-two chronic schizophrenic patients were assessed for abnormal movements, cognitive impairment, psychopathology, and medication history. Unequivocal evidence of movement abnormality on the Abnormal Involuntary Movement Scale divided the subjects into groups with (n = 13) and without (n = 9) involuntary movement anomaly. Age, education, length of illness, depressive symptoms, total symptom ratings, and medication variables did not differ in the two groups. However, the group with involuntary movements had more negative symptomatology, greater impairment on voluntary motor tasks, lower premorbid intelligence, and a trend toward poorer recall on mental status examination. These results demonstrate that schizophrenic patients with abnormal involuntary movements have more severe psychopathology as reflected in certain defect symptoms, more abnormal voluntary movements, and more cognitive impairment than schizophrenic patients without involuntary movements.

Adult↗