Search PubMed⌕ Search

Biomedical subjects

A Arthur

Publications and source records attributed to A Arthur.

At least 19 recordsLinked to original sources
PubMed1996

Radiofrequency catheter ablation of ventricular tachycardia in right ventricular cardiomyopathy: use of concealed entrainment to identify the slow conduction isthmus bounded by an aneurysm and the tricuspid annulus.

Radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) in patients with a right ventricular (RV) cardiomyopathy has only rarely been successful. This report demonstrates reentrant VT in the setting of RV cardiomyopathy in which the tricuspid valve annulus acted as one of the barriers of an isthmus of slow conduction, identified by the presence of entrainment with concealed fusion. The RF pulse was further targeted by analysis of the relationship between the postpacing interval with the tachycardia cycle length, and of the local activation time with the stimulation time. Long-term clinical follow-up has documented no recurrent VT.

Cardiomyopathies↗
PubMed1996

Systemic administration of an inhibitor of endothelin-converting enzyme for attenuation of cerebral vasospasm following experimental subarachnoid hemorrhage.

The potent vasoconstrictor peptide, endothelin-1 (ET-1), has been implicated in the pathophysiology of cerebral vasospasm that occurs after subarachnoid hemorrhage (SAH). This peptide is synthesized as a large prepropeptide that requires a series of modifying steps for its activation. The last of these steps involves the proteolytic conversion of a relatively inactive propeptide, Big ET-1, to its active, 21-amino acid peptide form. The enzyme responsible for converting Big ET-1 to ET-1 is a metalloprotease called endothelin-converting enzyme (ECE). In the present study the authors examined the effects of a newly developed inhibitor of ECE on responses to ET peptides in the normal basilar artery and on pathophysiological constriction in the spastic basilar artery after SAH. In the first series of experiments the authors examined normal basilar arteries in the rabbit, which were exposed transclivally and measured on-line using videomicroscopy. Intravenous administration or topical application of an active inhibitor of ECE, CGS 26303, blocked vasoconstrictor responses to topically applied Big ET-1 but not to ET-1. In contrast, topical application of a structurally related compound that does not inhibit ECE, CGS 24592, was ineffective in blocking vasoconstriction that was elicited by a topical application of Big ET-1. These findings indicate that CGS 26303 when administered systemically is capable of blocking the conversion of Big ET-1 to ET-1 in the basilar artery without affecting the ability of the vessel to respond to ET-1. In the second series of experiments the authors examined the effects of the ECE inhibitor on cerebral vasospasm after experimental SAH. Intraperitoneal administration of CGS 26303 via osmotic minipumps significantly attenuated the delayed spastic response of the basilar artery to an intracisternal injection of autologous blood. This study provides the first evidence that systemic administration of an inhibitor of ECE is capable of preventing cerebral vasospasm after SAH. The results reinforce a growing body of evidence that ETs play a critical role in the development of spastic constriction after SAH. Moreover, the findings indicate that blocking the conversion of Big ET-1 to its active ET-1 form using CGS 26303 may represent a feasible strategy for ameliorating cerebral vasospasm.

Animals↗
PubMed1995

Satisfying solutions? A review of some unresolved issues in the measurement of patient satisfaction.

The measurement of patient satisfaction has been encouraged by a growing consumer orientation in health care, especially since it yields information about consumers' views in a form which can be used for comparison and monitoring. However, drawing on literature from a variety of sources, this paper suggests that there remain several unresolved issues relating to the measurement of satisfaction, and some serious questions about the validity of the concept. It is argued that current approaches to measuring satisfaction may not be grounded in the values and experiences of patients; therefore satisfaction surveys could be denying patients the opportunity to have their opinions included in the planning and evaluation of health care services.

Consumer Advocacy↗
PubMed1995

Exploring patient satisfaction with out-patient services.

Despite the widespread use of satisfaction surveys to obtain patients' views about health services, the validity and relevance of self-completion questionnaire surveys has been questioned. This paper reports on an exploratory, qualitative investigation into patients' perspectives on satisfaction and dissatisfaction with out-patient care. Eighty-one new referrals to two out-patient clinics were interviewed before and after their first consultation. Of this initial sample, 23 were interviewed again at their follow-up appointment and a further 10 were interviewed in depth at a location of their choice. The features of the service that drew appreciative comments when they were thought to be present, and criticism when they were felt to be lacking, were: humanity, efficiency, informativeness and continuity of communication. Examples of these features are discussed using patients' own words to illustrate their perspectives. The study demonstrates that unstructured approaches to service evaluation can be employed to develop services which are genuinely listening to their users' views.

Ambulatory Care↗
PubMed1994

Guinea-pig contact sensitization assays.

After reviewing general aspects and the historical development of predictive animal skin sensitization tests, the recommended tests of the OECD and EC are discussed. Background information is given on the changes which occurred in the last 2 years. From the many factors known to influence induction and challenge of contact allergy in animals, the discussion is focused on the choice of induction concentration and the vehicle. The difference of general screening strategies in Europe and the USA is presented and discussed. The paper closes with a discussion on the importance of inhouse validation of the methods used for proper prediction of the sensitizing potential of chemicals and with remarks on predictive in vitro tests.

Allergens↗
PubMed1986

Bilateral lung abscess associated with a severe masticator space infection.

The clinician should be constantly aware of the danger of aspiration in cases of prolonged sepsis with profuse suppuration. In such cases, it might be wiser to establish dependent extraoral drainage, rather than relying solely on intraoral means. The chances of aspirating septic material and the resultant occurrence of pulmonary abscesses will be lessened.

Acute Disease↗
PubMed1985

The development of a male pseudohermaphroditic rat using an inhibitor of the enzyme 5 alpha-reductase.

Incomplete masculinization of the external genitalia occurred in male Sprague-Dawley rats treated with a potent inhibitor of enzyme 5 alpha-reductase at the critical period of sexual differentiation in utero. The studies were performed using the 5 alpha-reductase inhibitor, 4-methyl-4-aza-5-pregnan-3-one-20[s] carboxylate, one of a series of aza steroids known to competitively inhibit the enzyme 5 alpha-reductase. The degree of inhibition of male external genital development was dependent upon the dose of the inhibitor, and at a dose of 36 mg/kg X day, there was complete feminization of the external genitalia of the male animal with a urogenital sinus and a pseudovagina. These studies provide conclusive evidence for the hypothesis that 5 alpha-reductase activity and dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one) formation are essential for normal differentiation of male external genitalia. Epididymidis, vasa deferentia, and seminal vesicles were present at all doses of the inhibitor, suggesting testosterone dependency. However, confirmation of the testosterone dependency of Wolffian ductal differentiation awaits further studies, particularly comparison studies with the rabbit and dog, since Wolffian ductal differentiation in the rat, unlike the rabbit and dog, is not abolished with the antiandrogen, cyproterone acetate. The presence of prostatic buds, despite complete external genital feminization, was unexpected and suggests that these structures may have different thresholds of response for dihydrotestosterone. Prostatic differentiation may have a much lower threshold, requiring less dihydrotestosterone for differentiation.

5-alpha Reductase Inhibitors↗
PubMed1985

Decreased urinary C19 and C21 steroid 5 alpha-metabolites in parents of male pseudohermaphrodites with 5 alpha-reductase deficiency: detection of carriers.

The urinary 5 beta/5 alpha ring A-reduced metabolites of C19 and C21 steroids from obligate carrier parents of male pseudohermaphrodites with 5 alpha-reductase deficiency were analyzed by gas chromatography. Etiocholanolone/androsterone, 11 beta-hydroxyetiocholanolone/11 beta-hydroxyandrosterone, tetrahydrocortisol/allotetrahydrocortisol, and tetrahydrocorticosterone/allotetrahydrocorticosterone were the paired 5 beta/5 alpha-metabolite ratios measured. Increased mean 5 beta/5 alpha ratios were found for all paired metabolites compared to mean ratios in normal subjects. In men, the highest index of discrimination of the carrier state was the tetrahydrocorticosterone/allotetrahydrocorticosterone ratio, while in women, the etiocholanolone/androsterone ratio was more diagnostic. In obligate carrier men, plasma testosterone, dihydrotestosterone, androstenedione, and 17 alpha-hydroxyprogesterone levels were normal, as were testosterone/dihydrotestosterone ratios. These studies demonstrate a generalized defect in 5 alpha-reductase activity involving C19 and C21 steroid metabolism in obligate carrier parents and provide further confirmation of an autosomal recessive mode of inheritance in this condition. The data from parents of sporadic cases of male pseudohermaphrodites with primary 5 alpha-reductase deficiency suggest that there is a carrier rate within the general population, although the exact frequency remains unknown.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1984

Transposition and transposition immunity of transposon Tn3 derivatives having different ends.

Novel Tn1/3 derivatives that contained either two left- or two right-hand ends of the transposon were constructed in a small plasmid. Both transposed at reasonable frequencies to give normal transposition products, suggesting that only the 38-bp inverted repeats of Tn3 are essential for transposition. Plasmids containing transposon derivatives with only one end (either left or right) undergo transposase-dependent transposition between replicons at much lower frequencies, resulting in co-integrate molecules in which there is no substantial duplication of transposon DNA and that appear to be simple fusions of the two plasmids. Both the right and left halves of the transposon are separately able to confer transposition immunity to the plasmid, this immunity being inseparably linked to transposition proficiency and specificity.

DNA Transposable Elements↗
PubMed1983

Remission of Cushing's syndrome during pregnancy.

We present the first report of pregnancy with Cushing's syndrome due to an adrenal cortical adenoma, in which the hypercortisolemia disappeared during the third trimester of pregnancy, but recurred following the delivery of a normal male infant at 38 weeks by Cesarean section. The case is also unique because plasma ACTH levels were elevated during gestation and postpartum. Also, urinary estriol excretion was very low during the third trimester of pregnancy. The relationship of Cushing's syndrome and pregnancy are reviewed. This study points up some of the limitations of the routinely used dynamic tests of pituitary-adrenal function in Cushing's syndrome, and emphasizes the importance of various radiologic procedures in evaluation of patients with Cushing's syndrome.

Adenoma↗