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Biomedical subjects

J R Howell

Publications and source records attributed to J R Howell.

At least 19 recordsLinked to original sources
PubMed1989

Nocturnal penile tumescence in healthy 20- to 59-year-olds: a revisit.

This report presents data on normative nocturnal penile tumescence (NPT), based on a study of 48 healthy men aged 20-59 years, without complaints of erectile dysfunction. In general, the current measures show good concordance with those reported by Karacan and colleagues in 1976. The effect of "pathology-free" aging (from age 20 to 59) on electrographic measures of NPT is relatively modest, accounting for 8.4-14.4% of the variance. Furthermore, no age effect on visual estimates of erectile fullness or on buckling force estimates of penile rigidity were present. Maximum buckling force and maximum erectile fullness showed stability across the four decades of the Pittsburgh sample.

Adult↗
PubMed1988

Nocturnal penile tumescence is diminished in depressed men.

Although depressed individuals commonly report decreased libido, it was not known if such changes are accompanied by neurophysiological alterations. Preliminary studies suggest that some depressed men may manifest diminished nocturnal penile tumescence (NPT), an objective measure of erectile capacity. We report NPT findings in 34 male outpatients with major depression (SADS/RDC) and an age-matched group of 28 healthy controls. A 3-night electroencephalographic (EEG) sleep/NPT protocol was utilized, with penile rigidity (buckling force) determined on night 3. Analysis of night 2 data by MAN-COVA revealed significant effects for age, the covariate (F = 2.86, p = 0.002), and diagnosis (F = 2.32, p = 0.02). Depressed men had significantly diminished NPT time (F = 16.8, p less than 0.001), even when adjusted for sleep time (F = 13.4, p less than 0.001) or rapid eye movement (REM) time (F = 7.2, p less than 0.01). NPT time was reduced by greater than or equal to 1 SD below the control mean in 40% of depressives and was comparable to the level seen in 14 nondepressed patients with a clinical diagnosis of organic impotence. An intermediate proportion of depressed patients (38%) had maximum buckling forces less than or equal to 500 g, indicating diminished penile rigidity, when compared to controls (16%) and men with presumed organic impairment (93%) (p less than 0.001). Diminished NPT time and low buckling force were associated with a history of erectile dysfunction within the index depressive episode (p less than 0.001). These findings suggest that depression in men is associated with a potentially reversible decrease in erectile capacity, which may be associated with significant sexual dysfunction.

Adult↗
PubMed1988

Diagnostic performance of nocturnal penile tumescence studies in healthy, dysfunctional (impotent), and depressed men.

Nocturnal penile tumescence (NPT) studies were evaluated in 17 men with a clinical diagnosis of organic erectile dysfunction in comparison to age-matched healthy controls (n = 17) and depressed men (n = 17). The dysfunctional group had significantly fewer NPT episodes and reduced maximal penile tip changes when compared to healthy controls and depressed patients. Further, the dysfunctional group had significantly diminished erectile fullness and reduced penile rigidity. Diagnostic performance of polygraphic (night 1) and visual inspection (nights 2 or 3) components of the NPT protocol were examined in these criterion groups. A diagnostic classification based on polygraphic measures successfully discriminated 73.5% of dysfunctional and healthy control subjects, but classified 47% of depressives in the dysfunctional range. Use of visual inspection indices correctly identified 88% of the dysfunctional sample and 94% of normal controls, and reduced the "false-positive" rate in depression to only 18%. Results support the diagnostic utility of NPT studies, particularly when enhanced by visual inspection procedures. Nevertheless, the presence of major depression may confound interpretation of such studies.

Circadian Rhythm↗
PubMed1988

Assessment of sexual function in depressed, impotent, and healthy men: factor analysis of a Brief Sexual Function Questionnaire for men.

We report a study of sexual function in outpatient men with major depressive disorder (n = 42), compared with healthy control men (n = 37) and a clinic sample complaining of erectile dysfunction (n = 13). A principal-components factor analysis of the Brief Sexual Function Questionnaire confirmed differences in the clinical dimensions of sexual activity/performance, interest, satisfaction, and physiological competence. The four factors accounted for 72% of the variance in the analysis. Acceptable test-retest reliability, construct validity, and concurrent validity (with the Derogatis Sexual Function Inventory and a self-report behavioral log) were demonstrated. Parallel observations with findings from previous nocturnal penile tumescence studies in these same men are discussed.

Adult↗
PubMed1987

The effects of word orientation and imageability on visual half-field presentations with a lexical decision task.

Two studies examined the effects of word orientation and word imageability in a visual half-field procedure. The studies involved a lexical decision task in which items were presented in either a horizontal or vertical orientation randomly intermixed in Experiment 1 and blocked in Experiment 2. Overall, a RVF advantage resulted with horizontal items, yet no visual-field asymmetries were found with the vertical items. These results indicate that altering the orientation can affect visual-field superiority. It is proposed that the novelty of vertical displays leads to greater involvement of the right hemisphere. Imageability was related to performance only for horizontal displays; but there were no significant differences in imageability effects between the two visual fields. It is concluded that word imageability has little effect on visual-field differences, at least not for lexical decisions.

Female↗
PubMed1987

Formation and fate of nucleic acid and protein adducts derived from N-nitroso-bile acid conjugates.

14C-N-Nitrosoglycocholic acid (14C-NOGC) reacted with calf thymus DNA in vitro to give a number of carboxymethylated adducts (7-carboxymethylguanine [7-CMG], 3-carboxy-methyladenine [3-CMA] and O6-carboxymethylguanine [O6-CMG]). 7-CMG is excreted unchanged in urine, and its use as a marker for NOGC exposure was studied. Administration of 14C-NOGC results in a dose-dependent urinary excretion of 14C-7-CMG and in labelling of blood proteins, albumin and globin. The activity in albumin disappears in vivo, with a half-life very similar to that of albumin itself. The monitoring of carboxymethylated nucleic acid bases and proteins appears to be a useful way of monitoring endogenous formation of NOGC and related compounds.

Animals↗
PubMed1979

Nonlinear regression on multiple-dose data.

The examples are given to show how Metzler's nonlinear regression program can be used to estimate parameters in a model with multiple dosing. The model of one example is a set of equations involving sums of exponentials, whereas the other model is a set of differential equations reflecting first order absorption and Michaelis-Menten excretion. In both cases no data were given in one of the dosing intervals.

Computers↗
PubMed1978

Treatment of chlordecone (Kepone) toxicity with cholestyramine. Results of a controlled clinical trial.

Industrial workers exposed to the organochlorine pesticide, chlordecone (Kepone), had signs of toxicity in several organs. The extent of toxicity was proportional to the levels of this chemical in the tissues. In 22 patients, chlordecone was eliminated slowly from blood (half time of 165 +/- 27 days--mean +/- S.E.M.) and fat (half time of 125 days, with a range of 97 to 177), chiefly in the stool. Output of chlordecone in bile was 10 to 20 times greater than in stool, suggesting that chlordecone is reabsorbed in the "ntestine. Cholestyramine, an anion-exchange resin that binds chlordecone, increased its fecal excretion by seven times. In a five-month trial, cholestyramine significantly accelerated elimination of chlordecone from blood, with a half life of 80 +/- 4 days (S.E.M.) (P less than 0.005) and fat (half life of 64 days, with a range of 52 to 85) (P less than 0.05). Cholestyramine offers a practical means for detoxification of persons exposed to chlordecone and possibly to other lipophilic toxins.

Adolescent↗
PubMed1976

Curing and caring -- a proposed method for self-assessment in primary care organizations.

Key research in the area of quality assessment is reviewed and a method for periodic assessment in primary care organizations is proposed. The suggested approach is designed for administrative, rather than research, purposes. Therefore, it focuses on indicators that are both practical and realistic for use in periodic monitoring. The proposed method is two-staged and includes both technical performance (curing) and satisfaction (caring). At the first level of evaluation, general areas of performance are examined; these are key performance indicators in prevention, diagnosis, and management of illness, and questionnaires dealing with the accessibility and acceptability of care, coupled with objective measures of satisfaction. Those areas of performance that are not up to management standards are then examined in greater detail at the second level of evaluation. Using this approach, organizations can build a longitudinal picture of performance and chart their progress annually.

Consumer Behavior↗