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Biomedical subjects

M J Stevens

Publications and source records attributed to M J Stevens.

At least 91 records · Page 5Linked to original sources
PubMed1990

Alpha adrenoceptor activation and postreceptor contractile mechanisms in the human digital artery.

In order to compare postreceptor mechanisms of different alpha adrenoceptors, polyphosphoinositide hydrolysis and extracellular calcium entry stimulated by alpha-1 and alpha-2 adrenoceptor activation has been evaluated in the human digital artery, a tissue which contains both receptors. [3H]Inositol-I-PO4 accumulation during a 60-min exposure to an alpha-1 or alpha-2 agonist in the presence of 5 mM LiCl was used as an index of phosphatidylinositol-4,5-bisphosphate hydrolysis. Norepinephrine (1-30 microM) produced a concentration-related increase in [3H]inositol phosphate formation with an EC50 of 2.3 microM. Equieffective contractile concentrations of TL-99 (1 microM) and methoxamine (100 microM) produced similar increases in [3H]inositol-I-PO4 formation (1.41- and 1.70-fold increases over control, respectively). Norepinephrine EC50 values of 0.54, 1.7 and 1.0 microM were obtained for contractile responses in 1.25 mM Ca++, 0 mM Ca++ and 0 mM Ca++ + 0.1 mM ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid, respectively. Calcium omission (no ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid) produced similar inhibition of alpha-2 and alpha-1 adrenoceptor-mediated responses, assessed as inhibition of the area under the concentration-effect curve. Calcium omission generally produced a slightly greater inhibition of TL-99- or methoxamine-induced contractile responses than did nifedipine (0.1 or 1 microM), but the combination of calcium-omission and nifedipine practically abolished the contractile responses. However, the combination of a calcium omission and nifedipine did not prevent the accumulation of inositol monophosphate stimulated by TL-99 or methoxamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1989

Acute and chronic pain: pain dimensions and psychological status.

One hundred and ten outpatients with either acute or chronic low-back pain completed the McGill Pain Questionnaire, Beck Depression Inventory, State-Trait Anxiety Inventory, and Life Experiences Survey. Acutes and chronics did not differ on dimensions of pain, but significant correlations between pain dimensions and depression and state anxiety were found for chronics. Both groups showed elevated state anxiety; chronics also evidenced mild depression. Combined scores on depression, anxiety, and negative life change predicted sensory and affective pain for the pooled sample. These results confirm the role of psychological variables in the experience of clinical pain and underscore the highly affective nature of chronic pain.

Adaptation, Psychological↗
PubMed1989

Metastatic thymoma: case report.

A patient with myasthenia gravis who developed skeletal metastases 9 years following the complete excision of a thymoma is described. Several aspects of the case were noteworthy: (1) the original thymoma failed to demonstrate evidence of capsular invasion, (2) the association of myasthenia gravis with metastatic predominantly epithelial cell thymoma has not been previously documented, and (3) the time to development of metastatic disease is the second longest interval reported in the medical literature. The clinical implications of these features are discussed.

Humans↗
PubMed1989

Consumption of attention versus affect elicited by cognitions in modifying acute pain.

40 subjects were randomly assigned to conditions of high pleasure, low pleasure, high anger, or low anger in a 2 x 2 (intensity x affect) design. Although subjects used highly intense cognitions more than less intense ones, pleasant cognitions produced higher tolerance for pressure pain. Modification of pain may be mediated by specific affect rather than intensity or consumption of attention.

Adaptation, Psychological↗
PubMed1988

Corneal transplantation.

Corneal transplantation has become increasingly successful as a result of improved methods of tissue procurement and preservation, refined surgical techniques, better medical care, heightened public awareness and an expanded network of eye banks. Vision improves within a day of surgery and continues to improve for six months to one year. Careful screening of donors and donor corneal tissue is essential. Causes of transplantation failure include rejection, glaucoma and recurrent infections.

Corneal Transplantation↗
PubMed1987

Efficacy of aminohydroxypropylidene diphosphonate in the treatment of malignancy-associated hypercalcaemia.

Two patients with symptomatic malignancy-associated hypercalcaemia were treated with intravenously-administered aminohydroxypropylidene diphosphonate (APD). Both patients demonstrated dramatic falls in serum calcium concentration, and in urinary calcium and hydroxyproline excretion that were consistent with a reduction in the rate of bone resorption. Normocalcaemia occurred by day 5 and persisted for approximately three weeks after treatment. No significant side-effects were encountered. It was concluded that APD is a promising new agent in the management of hypercalcaemia that is associated with malignant disease and warrants further investigation.

Adenosine Diphosphate↗
PubMed1987

Antenatal ultrasonographic diagnosis of trisomy 18 (Edwards syndrome).

A 35-yr-old G7P6A0 presented at 28 weeks of gestation with an acute polyhydramnios. On ultrasonographic examination the diagnosis of trisomy 18 in the fetus was suspected. This was confirmed by chromosome analysis of the cultured amniocytes. The value of a systematic ultrasonographic examination, especially in every abnormal pregnancy, is briefly discussed.

Adult↗
PubMed1987

Human vascular alpha-adrenoceptors: the relevance of subtypes.

1. The post-receptor mechanisms of alpha 1 and alpha 2-adrenoceptor subtypes in guinea-pig aorta and human digital arteries have been explored. 2. Nifedipine antagonized contractile responses of human digital arteries to TL99 and methoxamine to a similar degree, thus suggesting that neither the alpha 1 nor the alpha 2 receptor is preferentially linked to calcium entry through voltage-operated channels of the cell membrane. 3. In the guinea-pig aorta, which contains only alpha 1-adrenoceptors, methoxamine-stimulated inositol phosphate (IP) production at similar concentrations was required to produce contractile responses. 4. In the human digital artery, noradrenaline also produced a significant increase in IP formation, but preliminary experiments have suggested that both TL99 and methoxamine stimulate IP production. 5. Thus, the present authors have been unable as yet to confirm, in a tissue which contains both alpha 1- and alpha 2-adrenoceptors, that the post-receptor mechanisms of the alpha subtypes are different.

Animals↗
PubMed1987

Dating of the endometrium by microhysteroscopy.

In 173 consecutive cases of hysteroscopy, the microhysteroscope was brought into contact with the anterior part of the fundus uteri. The vascular pattern of the endometrium was then visualized and photographed. As the vascularization of the endometrium changes during the menstrual cycle, a dating of the endometrium was made based on the blood vessel pattern. An endometrial biopsy was taken in each case. Hysteroscopically we were able to define five different phases in the menstrual cycle: early proliferative, late proliferative, early secretory, late secretory, and premenstrual-menstrual phase. Histopathological examination confirmed the hysteroscopical diagnosis of the phases in 72, 69.7, 81.3, 53.8 and 70%, respectively.

Biopsy↗
PubMed1987

Modifying acute pain by matching cognitive style with cognitive treatment.

To test whether congruence between cognitive style and cognitive coping would facilitate the attenuation of pressure pain, 30 verbalizers and 30 visualizers were assigned in equal numbers (ns = 10) to pleasant imagery, rational thoughts, and expectancy conditions. Separate 2 X 3 (cognitive style X experimental condition) analyses of covariance on pain tolerance and subjective discomfort indicated that imagery was superior to expectancy in raising tolerance. These findings are discussed in terms of the flexibility of cognitive coping and the content of the images and thoughts which were used.

Adaptation, Psychological↗
PubMed1986

Turcot's syndrome.

The first reported case of Turcot's syndrome (brain tumour with polyposis coli) in Australia is described. An awareness of the possible extracolonic concomitant conditions of polyposis coli should lead to the prompt investigation of any patient with either known polyposis or a family history of polyposis who develops a disorder of the central nervous system.

Adult↗
PubMed1986

Antagonism by nifedipine of alpha-1 and alpha-2 adrenoceptor-mediated responses of human digital arteries.

This study examines the effects of calcium-entry blockade by nifedipine on alpha-1 and alpha-2 adrenoceptor-mediated contractile responses of the human isolated digital artery to exogenous agonists and sympathetic nerve stimulation. Spiral strips of digital artery were mounted for isometric tension recording in physiological salt solution. Contractile responses to TL-99 and to norepinephrine in the presence of prazosin were effectively antagonized by rauwolscine and are therefore presumably mediated by alpha-2 adrenoceptors. Responses to norepinephrine in the presence of rauwolscine were antagonized by prazosin and are therefore mediated predominantly by alpha-1 adrenoceptors. Responses to methoxamine were antagonized by prazosin and, to a lesser extent, by rauwolscine, suggesting that this agonist is also activating alpha-2 adrenoceptors. Nifedipine antagonism of contractile responses was assessed as the percentage of inhibition of the area under the agonist concentration-effect curve or nerve stimulation frequency-effect curve. Nifedipine (10(-9) to 10(-7) M) inhibited responses to TL-99 and methoxamine to similar extents. Nifedipine (10(-8) and 10(-7) M) also had similar effects on the alpha-1 and alpha-2 adrenoceptor-mediated responses (in the presence of rauwolscine and prazosin, respectively) to either exogenous norepinephrine or sympathetic nerve stimulation. At concentrations up to 10(-6) M, nifedipine failed to reduce the efflux of [3H]norepinephrine produced by sympathetic nerve stimulation at either 2 or 8 Hz. We conclude that the alpha-1 and alpha-2 adrenoceptor-mediated contractile responses of the human digital artery are dependent to similar extents on calcium entry through the slow calcium channels of the cell membrane.

Electric Stimulation↗
PubMed1985

Neuronally released norepinephrine does not preferentially activate postjunctional alpha 1-adrenoceptors in human blood vessels in vitro.

Human isolated digital arteries and metatarsal veins, obtained postmortem, have been used to compare the effects of alpha-adrenoceptor antagonists on contractile responses to nerve stimulation. The antagonists used were prazosin, rauwolscine, BE 2254, and yohimbine. Rauwolscine (alpha 2-antagonist), as well as prazosin and BE 2254 (alpha 1-antagonists), in concentrations of 10(-9), 10(-8), and 10(-7) mol/liter, potently antagonized the frequency-response curves to nerve stimulation. Yohimbine (alpha 2-antagonist) was slightly less potent, failing to antagonize responses to nerve stimulation in arteries at the concentration of 10(-9) mol/liter significantly, but producing potent antagonism of responses in both arteries and veins at higher concentrations (10(-8), 10(-7) mol/liter). All antagonists inhibited the contractile responses to nerve stimulation to a greater extent in veins than in arteries. Rauwolscine (10(-9), 10(-8), and 10(-7) mol/liter) and BE 2254 (10(-7) but not 10(-8) mol/liter) significantly enhanced stimulation-induced tritium efflux in arteries and veins. These results suggest that alpha 2-adrenoceptor antagonists, despite their prejunctional effects, are potent antagonists of contractile responses to nerve stimulation. Thus, in these human blood vessels, endogenously released norepinephrine does not preferentially activate postjunctional alpha 1-adrenoceptors, but activates receptors with the properties of both the alpha 1- and alpha 2-adrenoceptor subtypes.

Adrenergic alpha-Antagonists↗
PubMed1984

The relationship of MacAndrew alcoholism scale scores to MMPI profile type and degree of elevation.

Collected MMPI data for 38 Caucasian males who were hospitalized in a Veterans Administration alcoholism treatment program. On the basis of a Q-factor analysis, three prototypic profiles were derived, which adequately described 92% of the sample. These profiles were labeled: Type I (scales 1 and 2), Type II (F-K, Scales 4 and 9), and Type III (Scales K, 3 and 4). Type II was found to be correlated positively with scores on the MacAndrew Alcoholism Scale. No relationship was found between MacAndrew Alcoholism Scale scores and magnitude of psychological distress, as measured by mean T scores.

Adult↗
PubMed1984

The relationship between sex-role orientation and the type A behavior pattern: a test of the main effect hypothesis.

Examined the relationship between sex-role orientation and the Type A behavior pattern. Eighty undergraduates were classified as high or low on masculinity and femininity on the basis of Bem Sex Role Inventory (BSRI) formed on student Jenkins Activity Survey (JAS) scores for pooled Ss, for males, and for females; each yielded a main effect for masculinity. JAS scores were correlated positively with BSRI Masculinity scores and not correlated with BSRI Femininity scores across pooled Ss, across males, and across females. These results are discussed in terms of their research and treatment implications.

Adult↗