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Biomedical subjects

A M Sterling

Publications and source records attributed to A M Sterling.

At least 19 recordsLinked to original sources
PubMed2001

Development and evaluation of a mass spectrometer-based continuous emission monitor for volatile organic compound emissions from combustion devices.

A mass spectrometer-based continuous emission monitor (MS-CEM) for organic compound emissions from combustion devices was developed and evaluated at the Louisiana State University (LSU) pilot-scale rotary kiln incinerator (RKI). The MS-CEM consists of a stack probe, heat-traced sampling line, vacuum pump, particulate filter, Nafion@ dryer and mass spectrometer. The mass spectrometer includes a computer that controls and optimizes the operation of the unit. The MS-CEM is capable of continuously analyzing up to 40 different volatile organic compounds on a real-time basis. The MS-CEM is capable of analyzing, computing and recording the analytical results for each and up to 40 different organic compounds in less than 0.3 s. Four different volatile organic compounds were mixed together and injected into the baghouse inlet while simultaneously analyzing each organic component exiting the RKI stack gas. The results obtained from MS-CEM were compared with the material balance values. The system response time (including the MS-CEM) varies from 1.1 to 1.5 min.

Air Pollutants↗
PubMed1995

Effect of atovaquone and atovaquone drug combinations on prophylaxis of Pneumocystis carinii pneumonia in SCID mice.

The prophylactic efficacies of atovaquone (ATQ) alone and in combination with azithromycin, clarithromycin, rifabutin, proguanil, PS-15, trimethoprim, co-trimoxazole, or dapsone were investigated in a SCID mouse model of Pneumocystis carinii pneumonia (PCP). ATQ alone was shown to have a significant dose-related effect, and at 200 mg/kg of body weight per day administered orally, the efficacy of ATQ was comparable to that of Septrin (co-trimoxazole). Of the drugs investigated orally in combination with ATQ, only dapsone (25 mg/kg/day) and to a lesser extent PS-15 (5 mg/kg/day) had any noteworthy antipneumocystis activity (at the doses examined) when administered alone. ATQ drug combinations affected the prophylactic efficacy of a subcurative dosage of ATQ (50 mg/kg/day given orally) in the following ways: dapsone (25 mg/kg/day) or co-trimoxazole (25 mg of sulfamethoxazole plus 5 mg of trimethoprim per kg/day) had no significant effect on ATQ, azithromycin (200 mg/kg/day) or clarithromycin (200 mg/kg/day) had a slight additive effect with ATQ, trimethoprim (100 mg/kg/day) or PS-15 (5 mg/kg/day) had an additive effect with ATQ, and proguanil (25 mg/kg/day) or rifabutin (200 mg/kg/day) had a marked synergistic effect on ATQ. The last result was particularly noteworthy as neither proguanil nor rifabutin was effective against PCP when administered alone. None of the drugs examined antagonized the prophylactic activity of ATQ in experimental PCP in SCID mice. The results suggest that clinical trials of ATQ with synergistic drug combinations may now be justified, particularly if such drug combinations improve ATQ's efficacy and broaden its spectrum of activity.

Animals↗
PubMed1983

Measuring softness of inner female urethra. Part I. Simple new device.

A new device is described to measure clinically the softness of the female urethra. It is a rod-shaped urethral sound with a longitudinal groove along its surface. The sound is constructed in sizes 12 to 24 French. Each has one groove which is 2 mm wide and either 2, 2.5, or 3 mm deep. The groove is 11 cm long. When inserted into the filled female bladder per urethram, the groove will span the urethra from the bladder to the outside. If the urethral inner lining is soft and deformable, it will fill itself into the groove and prevent leakage of urine from the bladder along the groove to the outside. If the urethra is relatively rigid, urine will leak from the bladder. This instrument permits testing of women to determine urethral properties in preventing leakage when studied with a range of probe sizes.

Elasticity↗
PubMed1983

Evaluation of inner urethral softness. Part II. Clinical study using new grooved probe device.

This study, in incontinent women, evaluates the effectiveness of a new device to measure properties of urethral softness. The device is a straight sound with a longitudinal groove cut along its surface. It is inserted through the urethra and into the bladder. A soft, deformable urethra is expected to fill itself into the groove and prevent the loss of urine from the bladder along the groove to the outside. Using this instrument it is learned that (1) postmenopausal women are less able to seal the urethra than younger ones; (2) as the urethra is stretched it is less able to form a seal; and (3) the anterior urethra is the weakest link in sustaining continence when tested by methods used in this program.

Adult↗
PubMed1980

Role of inner urethral softness in urinary continence.

Given adequate external squeeze upon suitable urethral geometry, continence depends on the mechanical properties of the outflow tract wall. Evidence indicates that these mechanical properties include an ability to deform and behave in a fluid-like manner.

Humans↗
PubMed1980

The variability of normal male voiding patterns measured by drop spectrometry.

Voidings from 7 healthy men were recorded by means of the urinary drop spectrometer. The voiding patterns were characterised by the trend drop frequency and the distribution of drop time intervals. The variability of these voiding patterns was studied by statistical techniques. The data were grouped for each person. Variances were considerable both within and between groups. Although individual differences in the mean values existed, the groups could not be separated from each other.

Adult↗
PubMed1977

The physical basis of some urodynamic measurements.

This report concerns certain principles of physics that are relevant to the clinical practice of Urology as well as the research urodynamicist. Supplemental material is available in previous publications for the physiologist, cardiovascular, dynamicist, anesthesiologist and the like. The material is fairly recent only in its application to the lower urinary tract. Pressure-volume relationships were applied to be cardiovascular system more than 20 years age. Indeed, for those interested in urodynamic methods, there is a vast fund of useful pertinent information in the literature on vascular dynamics. The problems of steady and unsteady flow in flexible structures are common to both specialties. It would be unfortunate if urodynamicists were required to learn of the phenomena and their implications by the drudgery of repeated measurements rather than taking guidance from previous work. This report is intended to serve as an introduction to the approach and, hopefully, will stimulate those who are interested in urodynamic methods to seek out this information and to interpret their measurements in the light of fundamental physical phenomena that have been described and analyzed.

Biomechanical Phenomena↗
PubMed1977

Physical information in the external urinary stream of the normal and obstructed adult male.

The qualitative status of physical information contained in the stream of the male lower urinary tract is traced from the bladder to the broken-up external stream. The progression of modifications of this information is discussed and it is argued that information remains in the drops. Electro-optical measurements of the drops leads to pulses which can be analysed for various types of information content. These confirms that there is potential clinical value in some aspects of the information.

Humans↗
PubMed1976

Measurement of the elasticity of the male urethral meatus by urinary drop spectrometry.

The urinary stream breaks up into drops shortly after leaving the external meatus. For normal males the frequency of the drops is related in a characteristic way to the flow rate. From this relation the elastic properties of an elastic constriction near the external meatus are calculated, using a theory of flow through distensible tubes. The elastic constriction behaves as if rigid at low flow rates, but distends elastically at flow rates above a critical value. This theoretical result is verified by observations of the stream emerging from a mechanical model, constructed with similar elastic properties. Functional meatal stenosis is associated with a lack of distensibility at the higher flow rates, which is reflected clinically in a changed relation between drop frequency and flow rate. Measurement of the relation, by the urinary drop spectrometer, offers a quick, non-invasive way of diagnosing this type of urethral obstruction.

Elasticity↗
PubMed1975

Megestrol acetate in treatment of benign prostatic hypertrophy.

In this study we found no significant effect on benign prostatic hypertrophy due to megestrol using standard clinical criteria. However, there is evidence using urinary drop spectrometer data which makes one suspect that megestrol does have a positive effect. If there is an effect, it is apparently so small as to be undetectable using the clinical protocol of this investigation. Since the urodynamic evidence does indicate a possibility of a positive effect, it appears reasonable to investigate further using a different protocol - perhaps a higher dosage and/or a more controlled test population.

Clinical Trials as Topic↗