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Biomedical subjects

R L Stout

Publications and source records attributed to R L Stout.

66 records · Page 4Linked to original sources
PubMed1975

Pulmonary blood flow determined by continuous analysis of pulmonary N2O exchange.

Measurement of mean pulmonary blood flow (Qp) as a function of pulmonary inert gas (N2O) uptake was studied with the aid of a mathematical model, fast response measurement of gas flow and gas concentrations at the mouth, and digital computer analysis of the data. The model treats the total pulmonary inert gas uptake as the sum of dead space, alveolar, lung tissue, and pulmonary blood flow uptakes. Analysis of any two breaths during breathing of a gas mixture (39 percent N2O, 21 percent O2, 40 percent N2 or He) in terms of the soluble (N2O) and the insoluble (N2 or He) inert gas yields two simultaneous equations with two unknowns which can be solved for Qp. No assumptions are required about the magnitude of the alveloar, dead space, or lung tissue volumes and constant FRC is not a requirement. The validity of the mathematical model and its sensitivity to known measurement errors was studied by computer simulation of respiratory gas exchange for N2O and N2. Comparison of Qp (N2O) with the direct Fick method (O2) in five anesthetized dogs showed agreement within plus or minus 20 percent. The proposed method has promise as a clinical method for determination of cardiac output on a breath-to-breath basis during regular breathing at rest or during exercise.

Animals↗
PubMedDate not supplied

Dibekacin intrarenal distribution characteristics and renal cortical elution kinetics. Comparison with gentamicin and tobramycin.

Dibekacin (3',4-dideoxykanamycin B) is a new semisynthetic aminoglycoside developed in Japan and one which has found wide clinical acceptance in that country. The antibacterial activity of this compound indicates that it is relatively similar to gentamicin. Since it appears that the intrarenal distributional characteristics and renal cortical kinetics of aminoglycosides provide some predictive information concerning the clinical incidence of nephrotoxicity, we designed a series of pharmacokinetic studies in healthy mongrel dogs which would define such kinetic information for dibekacin and would contrast the results with similar studies for gentamicin and tobramycin. The renal cortical kinetics of dibekacin, as developed in these studies, show that in a canine model the behavior of dibekacin is similar to that of gentamicin and significantly different from tobramycin. Dibekacin and gentamicin show reproducibly higher renal cortical tissue concentrations than tobramycin in both the acute infusion studies and multiple dosing studies. The results suggest that dibekacin may possess the same inherent nephrotoxic potential as that of gentamicin. In order to show any difference in clinical toxicity between gentamicin and dibekacin, a very extensive randomized, double-blind, prospective clinical trial of efficacy and toxicity will be needed.

Animals↗
PubMedDate not supplied

Reliability and validity of the longitudinal interval follow-up evaluation for assessing outcome of anxiety disorders.

The LIFE-UP, an instrument for prospectively following course for psychiatric disorders, has been extended to include Psychiatric Status Ratings (PSRs) for the DSM-III-R anxiety disorders panic (with and without agoraphobia), agoraphobia without panic, generalized anxiety disorder, social phobia, and simple phobia. This paper reports data on the reliability and validity of the LIFE-UP as used in the Harvard/Brown Anxiety Disorders Research Program. We found generally good reliability for the PSRs, both inter-rater and long-term test-retest. The reliability coefficients for the rater-administered instruments were very similar to those for the self-reports, suggesting that a large proportion of the variance was due to subject variability rather than rater variability. Reliability for the beginning of the year of follow-up was very similar to that for the time just before the interview. In addition, correlations with other measures of psychosocial function or anxiety symptomatology provided evidence for the external validity of the PSRs as measures of psychiatric morbidity.

Adolescent↗
PubMedDate not supplied

Maintaining reliability in a long-term psychiatric study: an ongoing inter-rater reliability monitoring program using the longitudinal interval follow-up evaluation.

The Longitudinal Interval Follow-up Evaluation (LIFE), has been shown to be a valid and reliable instrument for characterizing the week-by-week course of anxiety disorders examined retrospectively over the period of 1 year. Due to the chronic nature of these disorders, there is a need for reliable, valid instruments for measuring course over periods of several years if we are to learn more about the natural history of these disorders. This paper describes a rater-monitoring program designed to ensure long-term inter-rater reliability and prevent "rater drift". In this program, clinical interviewers score taped interviews and are required to maintain a median intra-class correlation coefficient (ICC) of at least 0.80 with the other raters. Raters also assess tapes from previous years, to ensure that they are using the same diagnostic criteria as earlier generations of interviewers. A reliability study was conducted to compare psychiatric status ratings (PSRs) collected using biweekly telephone interviews with the semi-annual interviews. The ICCs for panic, agoraphobia, social phobia, and generalized anxiety disorder were very good to excellent. Another reliability study examined the PSRs of subjects who had been previously lost to follow-up. ICCs for panic, agoraphobia, generalized anxiety disorder and depression were good to excellent. These results show that the LIFE, when used in conjunction with an intensive training and rater monitoring system, is a reliable instrument for use in longitudinal studies of the course of anxiety disorders.

Adult↗
PubMedDate not supplied

A comparison sample validation of "your workplace": an instrument to measure perceived alcohol support and consequences from the work environment.

This paper addresses the psychometric properties of Your Workplace (YWP), an instrument developed to measure perceived influence of workplace norms and attitudes on alcohol involvement and the experience of adverse consequences. Data were collected from a large, geographically dispersed sample of aftercare and outpatients recruited for a multisite clinical trial of alcoholism treatments, Project MATCH. Administration of YWP at the baseline assessment was restricted to workforce participants. A confirmatory factor analysis addressed instrument structure. Internal consistency and concurrent association between measures of general social support, alcohol specific support, and alcohol involvement were examined. YWP scales were found to have adequate internal consistency reliability. Correlation between YWP scales and concurrent measures of alcohol involvement were among the strongest found. Identification of workplace influences on alcohol involvement allows refined assessment and fosters a comprehensive approach to treatment of alcoholism.

Adult↗
PubMedDate not supplied

Optimizing the cost-effectiveness of alcohol treatment: a rationale for extended case monitoring.

There has been much research on and debate about the appropriate length of acute treatment for alcohol problems. In the United States, the lengthy and costly treatment programs of only a few years ago have been supplanted by ever-shorter and less intensive protocols, with little evidence that this trend will end soon. In this paper, we argue that, because of the chronic, recurrent nature of alcohol problems, an optimal system for delivering treatment services to alcoholics needs to focus on long-term engagement with clients. There is evidence from studies on research reactivity and telephone follow-up protocols that a low-intensity long-term protocol for maintaining contact with clients over time spans measured in years may result in better long-term clinical outcomes and reduced long-term health care utilization and costs. We describe a flexible long-term low-intensity follow-up protocol for alcohol abusers we call "case monitoring." This protocol is specifically designed to minimize long-term health-care use. We predict that such an intervention should be especially efficacious for women, persons with comorbid Axis I disorders, and persons lower in sociopathy. The design of a study to determine the clinical and health service effects of this intervention is also described.

Alcohol-Related Disorders↗
PubMedDate not supplied

Substance use disorder-PTSD comorbidity. Patients' perceptions of symptom interplay and treatment issues.

Forty-two patients with both a current substance use disorder (SUD) and posttraumatic stress disorder (PTSD) were asked about the interrelationship of their two disorders, their treatment preferences and experiences, as well as possible deterrents to receiving PTSD treatment. Patients perceived their two disorders to be functionally related. They reported that when one disorder worsened, their other disorder was more likely to worsen; when one disorder improved, the other disorder similarly improved. Consistent with these perceptions, SUD-PTSD patients favored simultaneous treatment of their two disorders. The majority of SUD-PTSD patients were never referred to PTSD treatment. Although several possible deterrents to PTSD treatment were identified, only lack of trust appeared to differentiate PTSD treatment compliers versus noncompliers. Implications of these findings on referral and treatment practices are discussed.

Adolescent↗
PubMedDate not supplied

Course of social functioning after remission from panic disorder.

While symptom status and social functioning have been observed to be correlated in many cross-sectional studies, little is known about the time course of change in functioning after a change in diagnostic status. Using data from a large longitudinal study of anxiety disorders, we present analyses of the time course of seven domains of social functioning up to 18 months before and after remission from panic disorder with or without agoraphobia. The effect of remission from panic disorder varies by domain. Four domains show a change in outcome, usually positive, after remission. The presence of major depressive disorder (MDD) affects the course of functioning for two domains. Generalized anxiety disorder (GAD) was observed to have effects on five of seven domains. For some domains there is improvement at approximately the same time as change in diagnostic status, although progressive change was seen in others. The amount of improvement was modest on average, indicating that other factors beyond panic symptoms may limit post-remission improvement in social functioning.

Major Depressive Disorder↗
PubMedDate not supplied

Distinguishing sympathomimetic amines from amphetamine and methamphetamine in urine by gas chromatography/mass spectrometry.

Derivatives of seven commonly used sympathomimetic amines and two "designer amines" were isolated from urine, separated chromatographically from amphetamine and methamphetamine, and determined by mass spectrometry with selected ion monitoring. The drugs included ephedrine, propylhexedrine, pseudoephedrine, phenylpropanolamine, hydroxynorephedrine, phenylephrine, phentermine, methylenedioxyamphetamine (MDA), and methylenedioxy methamphetamine (MDMA). The drugs were liquid extracted from urine and derivatized by either heptafluorobutyric anhydride (HFBA) or 4-carbethoxyhexafluorobutyryl chloride (4-CB). Because the base peak ions for ephedrine, pseudoephedrine, propylhexedrine, MDMA, and phentermine are identical to methamphetamine (e.g. 254 amu for HFBA) and those for phenylephrine, hydroxynorephedrine, phenylpropanolamine, and MDA are identical to amphetamine (e.g. 240 amu for HFBA), a table of selected ions was developed for all 11 drugs that distinguished amphetamine and methamphetamine from the sympathomimetic amines with either HFBA or 4-CB. The distinguishing ions rely on the ring structure of the different drugs and fragmentation associated with that structure. The 4-CB reagent partially derivatized the hydroxy-containing sympathomimetic amines, while the HFBA completely derivatized all the sympathomimetic amines. Furthermore, false positive results for the 4-CB reagent were found only for methamphetamine (20-2250 ng/mL of methamphetamine) when high concentrations (greater than 5 micrograms) of ephedrine or pseudoephedrine were present in the specimen. These results are related to a combination of injection port temperature and cleanliness of the injection port sleeve.

Amphetamine↗