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Biomedical subjects

J M Stevenson

Publications and source records attributed to J M Stevenson.

At least 55 records · Page 3Linked to original sources
PubMed1988

Methodology to measure the transient effect of occlusion on skin penetration and stratum corneum hydration in vivo.

The effect of short duration occlusion on skin penetration and stratum corneum water content was studied in vivo in eight human subjects. Percutaneous absorption of hexyl nicotinate was monitored non-invasively by laser Doppler velocimetry (LDV) following each of three randomly assigned pre-treatments: untreated control, 30 min occlusion with a polypropylene chamber and 30 min occlusion followed by exposure to ambient conditions for 1 h. Stratum corneum water content after the same pre-treatments was measured with the dielectric probe technique. The local vasodilatory effect of the nicotinic acid ester was quantified using LDV by the onset of increased blood flow, the time of maximal increase in response, the magnitude of the peak response and the area under the response-time curve. Each of these parameters was significantly different, immediately following occlusion, from the untreated control values. However, if the occluded site was exposed for 1 h prior to hexyl nicotinate application these parameters did not differ significantly from the controls. Stratum corneum water content (expressed as a percentage of a maximal value) showed the same behaviour: the pre-treatment control value was 31.8 +/- 4.8%; after 30 min occlusion, this had risen to 46.9 +/- 6.2%; 1 h later, the reading had returned to 32.1 +/- 6.2%. There was a significant correlation between stratum corneum water content and area under the LDV response-time curve. It appears, therefore, that this method may be useful for quantifying the relationship between increased stratum corneum hydration and enhanced percutaneous absorption in vivo in man.

Adult↗
PubMed1987

Steady-state model for plasma free and platelet serotonin in man.

A steady-state physiological flow model has been developed for predicting plasma free serotonin (5-HT), and platelet 5-HT, concentrations in man. The basic assumptions of the model are that 5-HT is produced in the wall of the intestine, enters the portal circulation at a constant rate, and is cleared by the lung, liver, kidney, and capillary bed. When a priori best estimates of the 5-HT production rate and organ extraction efficiencies were substituted into formulae describing the model, a predicted value for plasma free 5-HT of 304 pg/ml was obtained, in good agreement with a previously observed mean (+/- SE) of 387 +/- 84 pg/ml. The effects of varying production rate and extraction efficiency parameters on predicted levels of plasma free 5-HT are examined. The practical implications of the model and its possible utility in elucidating the causes of altered plasma free or platelet 5-HT seen in certain conditions are discussed.

Blood Platelets↗
PubMed1987

Time and age trends for sinonasal cancer in Connecticut incidence and US mortality rates.

Population-based rates for sinonasal cancer are examined in US mortality data among whites and in Connecticut incidence data. The observed rates are fitted to a log-linear model in order to examine the effect of each of the three variables, age, period and cohort, simultaneously for each sex. For Connecticut incidence, there is little evidence of either an increase or decrease from 1865 to 1955 birth cohorts. For the US mortality rates, from the 1875 to 1950 birth cohorts, there is a decline by more than twofold in men and more than threefold in women. Monitoring of those trends is discussed with respect to increases in exposure to cigarette smoking and formaldehyde. Regarding the age distribution, both incidence and mortality data are consistent: men show a linear increase of the log (rate) with log (age) in a fashion characteristic of other epithelial nongynecologic malignancies; for women, in contrast, there is a downward curvature around age 50 followed by an upward curvature in the 55 to 70 age range. The rate in most postmenopausal age groups is 20% to 67% of the rate expected on the basis of a linear increase of the log (rate) with log (age). The age patterns in women are similar to "Clemmesen's hook" observed for female breast cancer. There is evidence that the pattern in female subjects differs significantly from that for male subjects. The female age pattern requires confirmation in other populations. An etiologic role for sex hormones is hypothesized in view of that age distribution and in view of physiologic and laboratory observations.

Age Factors↗
PubMed1986

Pharmacodynamic measurement of percutaneous penetration enhancement in vivo.

Enhanced skin penetration of hexyl nicotinate was measured in human subjects using laser Doppler velocimetry (LDV). The local pharmacodynamic response (vasodilatation) to hexyl nicotinate permitted the kinetics and extent of penetration to be evaluated following topical application of 10 mM drug in a 60:40 v/v propylene glycol: isopropyl alcohol vehicle. Prior to hexyl nicotinate administration, the application site was either untreated (control) or subjected to one of four 30-min pretreatments: (a) occlusion with a polypropylene chamber; (b) occlusion (as in a) in the presence of 0.3 mL of the vehicle; (c) occlusion (as in a) in the presence of 0.3 mL of the vehicle containing 25% 2-pyrrolidone; and (d) occlusion (as in a) in the presence of 0.3 mL of the vehicle containing 25% laurocapram (1-dodecylhexahydro-2H-azepin-2-one). The time-course and magnitude of the LDV response were characterized by the onset of action, time to peak, peak height, and area under the curve (AUC). The onset of action and time to peak were significantly shortened, and the peak height and AUC significantly increased with pretreatments a-d. For example, time to peak values were 35 +/- 4, 29 +/- 3, 22 +/- 5, 19 +/- 4, and 17 +/- 4 min for control and pretreatments a-d, respectively (n = 8). Pretreatments with vehicle, vehicle plus 2-pyrrolidone, and vehicle plus laurocapram did not cause LDV-detectable alterations in skin blood flow. The data support, therefore, a novel, simple, noninvasive, and objective demonstration of enhanced skin penetration of hexyl nicotinate in humans.

Adult↗
PubMed1985

The use of propranolol in the treatment of anxiety disorders.

The authors review the available literature on the use of propranolol in the treatment of anxiety disorders. First studied in 1966, propranolol has been shown to be most effective in the control of certain somatic symptoms associated with anxiety. Despite these studies, however, it is still not certain where this beta-adrenergic blocker fits into the overall treatment of anxiety disorders. Reasons for this uncertainty and other related problems are discussed.

Anxiety↗
PubMed1985

Finger release sequence for fastball and curveball pitches.

The purpose of this study was to determine the action of the thumb, index, and middle fingers in releasing fastballs and curveballs for nine right-handed college pitchers. Micro-switches for the fingers were created by using two strips of electroconductive tape and a ball covered with electroconductive paint. Time data, accurate to 10(-4)s, were initiated by the stride foot onto a floor mat switch. When each digit left the ball, a corresponding timer was triggered with the final channel tripped by a contact switch in the catcher's glove. A total of 103 fastball and 88 curveball trials had complete data for each of the variables studied. Results showed that for the fastball, in 91.1% of the cases, the thumb preceded the middle and index fingers by approximately 6 ms. (p less than .001) but there was no significant difference between the middle and index fingers. The curveball data indicated that five of the nine pitchers had a definite release sequence of thumb first followed by middle then index finger (p less than .001). In total, 72.7% of the curveballs thrown had a release sequence of thumb, middle, and index fingers and 24.0% had a middle, thumb, index finger release sequence. The remaining 2.3% of the pitches had either similar times or odd combinations of release sequence.

Baseball↗
PubMed1983

Staff training through collaboration: the training resources center.

As fiscal resources for mental health programs dwindle, it is becoming increasingly important to preserve non-direct-service priorities such as staff development. The West Virginia Training Resources Center, a collaborative program operated by the West Virginia Department of Health and the West Virginia University department of behavioral medicine and psychiatry, addresses problems of staff training in the state mental health service system. The authors discuss the development of the center and its functions as provider of training programs, sponsor of statewide training conferences, and clearinghouse of information and expertise. They also discuss problems stemming from the increased need for continuing education for paraprofessionals, the use of outside consultants, and the relationship between academia and the health service sector.

Community Mental Health Centers↗
PubMed1982

Hypothalamic-pituitary-adrenal axis activity and tricyclic response in major depression.

Hypothalamic-pituitary-adrenal (HPA) axis activity was studied in 28 endogenously depressed, hospitalized patients. Measures of HPA activity obtained were baseline serum cortisol level, 24-hour urinary free cortisol excretion, and an overnight 2-mg dexamethasone suppression test. The patients then received double-blind and randomized treatment with imipramine hydrochloride, 150 mg daily, or amitriptyline hydrochloride, 150 mg daily, for four weeks. Four-week treatment response of all patients was compared with pretreatment HPA axis variables, and higher cortisol values after dexamethasone administration were found to be significantly correlated with greater improvement. There were no significant differences between imipramine and amitriptyline response, however, when improvement with each drug was compared with the pretreatment HPA variables.

Adult↗
PubMed1981

Symptoms of depression among blacks and whites in an urban community.

Prevalence of reported depressive symptoms among blacks and whites is examined using data from a survey (N = 3119) conducted in Alameda County, California, in 1974. Based on crude rates, depressive symptoms were more prevalent among blacks than whites. However, adjusting statistically for the effects of age, sex, education, income, marital status, and employment essentially eliminated the black/white differential. These data corroborate the results reported by Comstock and Helsing (Psychol. Med., 6: 551-563, 1976) as well as the results of several other investigations carried out in various U.S. communities.

Adolescent↗
PubMed1980

Evaluating a conjoint psychiatric-medical inpatient unit--a one year follow-up study of depressed patients.

In an effort to evaluate a new Conjoint Psychiatric-Medical Unit, depressed patients treated on the service are compared with depressed patients treated on the same unit when it was a psychiatric service. Recidivism, return to responsibilities, and patient satisfaction are the parameters that are compared, and no significant differences are noted. These findings would suggest that the new Inpatient Service appears to be an effective treatment modality for depressed patients.

Adult↗