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Biomedical subjects

J M Rubin

Publications and source records attributed to J M Rubin.

At least 37 records · Page 2Linked to original sources
PubMed1999

A randomized, double-masked, placebo-controlled parallel study of loteprednol etabonate 0.2% in patients with seasonal allergic conjunctivitis.

OBJECTIVE: To evaluate the effects of loteprednol etabonate (LE) 0.2% in reducing the signs and symptoms of seasonal allergic conjunctivitis. DESIGN: Randomized, double-masked, placebo-controlled, parallel group multicenter study of 6 weeks duration. PARTICIPANTS: A total of 135 patients with signs and symptoms of seasonal allergic conjunctivitis participated. INTERVENTION: All patients received either LE 0.2% or placebo (vehicle) four times a day in both eyes for 42 days. MAIN OUTCOME MEASURES: Bulbar conjunctival injection (primary sign) and itching (primary symptom) over the first 2 weeks of treatment was measured. RESULTS: A reduction in severity was seen in both LE and placebo groups for bulbar conjunctival injection (1.5 vs. 1.0 units on a 0-3 scale) and itching (3.4 vs. 3.0 units on a 0-4 scale) over the first 2 weeks. The treatment effect by these measures was -0.5 and -0.4 units in favor of LE (P < or = 0.008). Resolution (i.e., the proportion of patients with signs or symptoms no longer present) at day 14 strongly favored LE-treated patients (36% and 15%; 58% and 38%, for injection and itching, respectively). Both treatments were well tolerated. One patient in each treatment group (1 of 67 and 1 of 68, respectively) had an elevation of intraocular pressure of 10 mmHg or greater during the 6 weeks of treatment. CONCLUSIONS: Loteprednol etabonate 0.2% was more effective than placebo in the treatment of seasonal allergic conjunctivitis. Loteprednol etabonate 0.2% had a safety profile comparable to placebo.

Adult↗
PubMed1999

Frequency analysis of echo texture in tendon.

A texture discriminant based on spatial frequencies is proposed for characterizing B-scans of Achilles' tendon. The anisotropic echo texture of normal tendon has an ellipsoidal spatial spectrum that can be quantified by the ratio of the major-to-minor axis and by the direction of the major axis. Applying a moving window to the B-scan, a corresponding tissue elliptical axis ratio (TEAR) image is derived that segments out tendon. The algorithm was applied to B-scan images taken from 13 volunteers, 6 of whom had tendon abnormalities: tendon rupture (n = 3) or cholesterol deposits (xanthomas) in patients with heterozygous familial hypercholesterolemia (n = 3). The average TEAR value was 1.75 +/- 0.17 for normal tendon, 1.04 +/- 0.06 for torn tendon, and 1.31 +/- 0.16 for tendons with xanthomas. The dispersion of the directionality vectors was used to further differentiate tendons with xanthomas from normal tendons. This technique appears to be useful for characterizing both diffuse and focal tendon abnormalities.

Achilles Tendon↗
PubMed1999

Relationship between the resistive index and vascular compliance and resistance.

PURPOSE: To evaluate the dependence of the resistive index (RI) on not only vascular resistance but also vascular compliance. MATERIALS AND METHODS: An in vitro model that made use of a pulsatile pump, blood-mimicking fluid, and variable compliance and resistance was used to investigate the relationship between the RI and both vascular compliance and resistance. RESULTS: In the absence of vascular compliance, the RI was independent of vascular resistance. With vascular compliance, the RI was dependent on vascular resistance and increased with increasing resistance. The higher the compliance, the more the RI was affected by resistance. CONCLUSION: The RI is misnamed and should actually be called the "impedance index" because resistance and compliance interact to alter the Doppler arterial waveform. A greater understanding of this relationship may enable future studies that take both resistance and compliance into account to better detect pathologic conditions.

Compliance↗
PubMed1999

Stenosis of the main artery supplying an organ: effect of end-organ vascular resistance on the poststenotic peak systolic velocity in an in vitro hydraulic model at Doppler US.

PURPOSE: To test the hypothesis that increased end-organ vascular resistance reduces blood flow to the kidney, thus reducing the mean velocity in the renal artery and secondarily lowering the peak systolic velocity (PSV). MATERIALS AND METHODS: An in vitro hydraulic model with a pulsatile pump, blood-mimicking fluid, interchangeable stenoses, and variable compliance and resistance was used to investigate the relationship between end-organ vascular resistance and poststenotic PSV. RESULTS: Poststenotic PSV was mildly dependent on end-organ vascular resistance and decreased with increasing resistance. CONCLUSION: The results help explain some of the reported variability from using poststenotic PSV to detect hemodynamically significant renal arterial stenoses, but the effect is not great enough to completely explain the variability. Other factors not investigated in this study must be at work as well.

Blood Flow Velocity↗
PubMed1999

Effect of downstream cross-sectional area of an arterial bed on the resistive index and the early systolic acceleration.

PURPOSE: To evaluate the effect of the increase in total cross-sectional area of arteries as they branch beyond the main trunks on the resistive index (RI) and early systolic acceleration (ESA). MATERIALS AND METHODS: An essentially noncompliant in vitro model that used a pulsatile pump, blood-mimicking fluid, and a branching tubing network that could be configured to produce a downstream cross-sectional area one, two, four, or eight times that of the feeding vessel was used to investigate the relationship, if any, between arterial bed cross-sectional area and the RI and ESA. RESULTS: The mean ESA in the branching network was inversely proportional to cross-sectional area, decreasing by approximately a factor of two for every doubling of the cross-sectional area. The mean RI in the branching network decreased with increasing cross-sectional area, but not as greatly as the ESA did; the mean RI in the bed with eight times the upstream cross-sectional area had an RI that was approximately three-fourths the upstream RI. These relationships are real, as the slopes of the plots (ESA vs cross-sectional area, P = .001; RI vs cross-sectional area, P < .02) are significantly different from zero. CONCLUSION: RI and ESA decrease as a result of increasing downstream cross-sectional diameter of the arterial bed.

Arteries↗
PubMed1999

Speckle decorrelation flow measurement with B-mode US of contrast agent flow in a phantom and in rabbit kidney.

PURPOSE: To use speckle decorrelation in the presence of ultrasonographic (US) contrast agent as an alternative flow measurement technique to Doppler US. MATERIALS AND METHODS: In vivo and in vitro studies were performed. A tube with flowing saline solution containing contrast agent was positioned horizontally across a US image. The amount of decorrelation between a series of images was recorded. The flow profile across the tube was generated by averaging the decorrelation values and was compared with a Doppler frequency shift image. In addition, B-mode images of six rabbit kidneys were obtained during and after intravenous injection of contrast agent. Images were analyzed to compute the correlation between successive points in time. RESULTS: The velocity profiles across the tube were parabolic, with the fastest flow rates measured in the center of the tube. In the rabbit kidneys, measurements indicated the largest decorrelation rates occurred in the larger vessels. The cortical decorrelation rates were significantly slower than those for the hilar vessels (P < .05) and were relatively angle independent. CONCLUSIONS: Decorrelation flow measurements can be used to estimate flow in vitro and in vivo similar to measurements obtained with Doppler US but with less angle dependence. These measurements could lead to a US perfusion technique.

Animals↗
PubMed1999

Stenosis of the main artery supplying an organ: effect of end-organ vascular compliance on the poststenotic peak systolic velocity.

Prior studies have shown variable results using poststenotic peak systolic velocity to detect hemodynamically significant renal artery stenoses. We postulated that vascular compliance, which affects the arterial waveform and varies by a factor of at least 5 in vivo, affects the peak systolic velocity, perhaps explaining the aforementioned variable results using peak systolic velocity to detect stenoses. A hydraulic model was used to investigate the relationship between end-organ vascular compliance and the peak systolic velocity. The peak systolic velocity was found to be mildly dependent on vascular compliance, decreasing with decreasing compliance. These results help explain some of the reported variability using peak systolic velocity to detect hemodynamically significant renal artery stenoses, but the effect is not great enough to explain the variability completely. Other factors not investigated in this study must exist that also affect peak systolic velocity.

Blood Flow Velocity↗
PubMed1999

Transabdominal power Doppler sonography of the normal early placenta.

OBJECTIVE: To evaluate how well transabdominal power Doppler sonography, a new method of colour Doppler sonography, visualizes the vasculature of the early placenta. METHODS: Evaluation of intrachorionic/intraplacental vasculature in 15 normal, singleton gestations of 8 to 18 weeks. RESULTS: Intrachorionic/intraplacental vessels were identified in all gestations, except the earliest (8 weeks). The number of vessels detected increased with increasing gestational age. Intrachorionic/intraplacental Doppler waveforms of maternal arterial origin were identified in gestations of 8.5, 9.5, and 11.5 weeks. CONCLUSIONS: Transabdominal power Doppler sonography detects intrachorionic/intraplacental vasculature at least as early as 8.5 weeks. Intervillous arterial flow of maternal origin is present in the first trimester, confirming the results of a recent transvaginal colour Doppler sonographic study, and contradicting earlier studies suggesting that such flow is not present in the first trimester.

Female↗
PubMed1998

3-D color Doppler image quantification of breast masses.

In this article, new measures obtained from color Doppler images are introduced and a pilot study is described, in which these and previously published indices are evaluated for use in future work. Twenty women with breast masses observed on mammography and going to surgical biopsy were studied. Of the masses, 11 proved to be benign and 9 were malignant. Both 3-D mean frequency shift (f-CDI) and power mode Doppler (p-CDI) imaging were performed. To identify the mass and other regions of interest, vessels were displayed as rotatable 3-D color volumes, superimposed on selectable grey-scale/color flow slices. Doppler signals were recorded in each of 6 ellipsoidal regions of interest in and around the mass and 2 in normal tissues. Seven measures were computed in each region, three from power mode, two from mean frequency and two from combinations of both. Radiologists rated the grey-scale appearances of the masses on a scale of 1 to 5 (5=most suspicious) for each of 6 conventional grey-scale criteria. Of the individual vascularity measures in individual ROIs, the log speed-weighted pixel density and log power-weighted pixel density in the lesion internal periphery showed the greatest discrimination of malignancy, although neither was statistically significant nor as good as the peak variables described below. The mean visual grey-scale rating was the best discriminator overall, but two peak vascularity measures each made promising scatterplots in conjunction with the average visual grey-scale rating. These two vascularity measures were the log peak normalized power-weighted pixel density (peak NPD) and log of peak mean Doppler frequency times the peak NPD (vM x NPD(M)). Each of these two values was the maximum in any one of the five chosen ROIs closely associated with the mass. A possible rationale for the relative success of these peak values is the blood signal's normalization and the inhomogeneity of most breast cancers and the expectation that the highest velocities (shunting) and largest collections of blood are not necessarily in the same region in and around the tumor. Peak NPD of cancers varied with age, decreasing by a factor of 45 from 33 to 77 y.

Adult↗
PubMed1998

Transcutaneous interruption of ultrasound contrast agents for blood flow evaluation.

RATIONALE AND OBJECTIVES: The ability to create short boluses in targeted arteries with rapid rise times is limited by the transport of bubbles from the venous to arterial portion of the circulation. Acoustic interruption of contrast agent in arteries may create the short boluses necessary for simple wash-in/wash-out measures of blood flow. METHODS: An ultrasound contrast agent was used with spectral Doppler ultrasound to observe contrast interruption in femoral arteries and VX2 carcinoma in a rabbit model. At an upstream location in the femoral artery, single, sinusoidal ultrasound tone bursts at 1.8 MHz with durations of 0.25 to 1 seconds were applied to interrupt the flow of contrast agent injected intravenously. RESULTS: In VX2 carcinoma, bursts as short as 40 cycles produced contrast interruption lasting only one cardiac cycle within the tumor periphery and I(SPPA) <3 W/cm2 produced measurable interruptions. CONCLUSIONS: Acoustic fields applied transcutaneously interrupted flow of contrast agents to form temporally short negative boluses.

Animals↗
PubMed1998

The potential benefit of a home fire safety intervention during emergency medical services calls.

OBJECTIVE: To determine how often house fires occur at 1- and 2-family dwellings visited previously by emergency medical services (EMS) personnel and whether these visits were missed opportunities for a point-of-contact home fire safety intervention. METHODS: A retrospective, consecutive, case series analysis of all Milwaukee Fire Department alarm responses during 1994 was performed. Measurements included date of service, type of response, property type, dollar loss estimate, number of injuries and fatalities, cause of alarm, and presence of an operational smoke detector. Descriptive, chi2, and relative risk statistics were used to describe the relationship between EMS responses and fire responses at 1- and 2-family dwellings. RESULTS: The Milwaukee Fire Department dispatched 94,378 requests for service to 43,556 addresses. 16,150 addresses generated multiple requests; 7.2% (1,162/16,150) were for an "alarm of fire" response [relative risk 1.83 (95% CI: 1.69-1.99) for addresses with multiple requests vs those with a single request for service]. Most [62% (721/1,162)] of the addresses were visited by EMS personnel prior to the alarm; 28% (205/721) were 1- and 2-family dwellings. A mean of 1.8 (376/205) EMS responses occurred prior to the "alarm of fire" response; 121 addresses received 1 response, 46 received 2, 18 received 3, and 20 received > or = 4 responses. Of 169 addresses with complete data, there was a total fire dollar loss of $1,963,020 (1994) along with 32 injuries and 0 fatalities. While 47% (80/169) of the 1- and 2-family dwellings had a smoke detector present, only 17% (29/169) of the dwellings had an operational smoke detector. CONCLUSIONS: A point-of-contact home fire safety intervention appears of potential benefit for frequent users of EMS care. Determination of the presence of an operational smoke detector in 1- and 2-family dwellings may be a useful injury prevention act during such EMS calls.

Accident Prevention↗
PubMed1998

Out-of-hospital treatment of hypoglycemia: refusal of transport and patient outcome.

OBJECTIVES: Patient refusal of transport after treatment of hypoglycemia is common in urban emergency medical services (EMS) systems. The rate of relapse is unknown. The goal of this study was to compare the outcomes of diabetic patients initially refusing transport (refusers) and those transported to an ED. METHODS: All paramedic runs from January to July 1995 were retrospectively reviewed. Inclusion criteria were adult patients with a field assessment of hypoglycemic signs/symptoms, and a fingerstick glucose <80 mg/dL. Data for analysis included paramedic run duration, patient demographics, and refusal or acceptance of transport. Patient outcome was obtained from a review of hospital and medical examiner records. Relapse was defined as hypoglycemia necessitating EMS activation or an ED visit within 48 hours of the initial episode. Student's t-test and chi2 analysis were used to compare means and rates, respectively. RESULTS: Over the 7 months, 374 patients made 571 calls to 9-1-1 that met inclusion criteria (5.2% of all paramedic runs). Of these, 412 were refusers (72.2%) and 159 were transported patients (27.8%). The hospital records of 4 transported patients were unavailable. Sixty-three transported patients were admitted (11.2%), with 1 death from prolonged hypoglycemia. The rates of relapse did not differ between the refusers and the transported patients (p > 0.05). Twenty-five relapses occurred among the refusers (6.1%), with 14 repeat refusals, 11 transports, 5 admissions, and no deaths. There were 7 relapses among the transported patients (4.4%), with 2 refusals, 5 transports, 2 admissions, and no deaths. The paramedic run time was significantly shorter for the refusers than for the transported patients (p < 0.05). CONCLUSIONS: The out-of-hospital treatment of hypoglycemic diabetic patients appears to be effective and efficient. Independent of the patient's refusal or acceptance of transport, the out-of-hospital treatment of hypoglycemic patients in this system appears to be safe.

Adult↗
PubMed1997

Ultrasonic characterization of in vitro osteoarthritic articular cartilage with validation by confocal microscopy.

The majority of adults over the age of 65 y develop osteoarthritis (OA), a joint disease characterized by degeneration of articular cartilage and subchondral sclerosis. Early in the disease, the articular cartilage surface begins to change histologically from a smooth to a rough or fibrillated appearance. A prerequisite for any chondroprotective pharmacological intervention is detection of OA in its preclinical phase. Current diagnostic imaging modalities, such as radiographs or (nuclear) magnetic resonance imaging, either cannot directly image the cartilage surface or lack sufficient resolution to detect surface fibrillations. We have developed an ultrasonic technique that can be used to characterize these surface fibrillations directly. We present our in vitro results with validation by laser-based confocal microscopic imaging.

Adult↗
PubMed1997

The 3D and 2D color flow display of breast masses.

A prospective study was performed in 24 women with breast masses on mammography going on to surgical biopsy. 2D and 3D power mode and frequency shift color flow Doppler scanning and display were compared. Vessels were displayed as rotatable color volumes in 3D, superimposed on gray-scale slices. The latter were stepped sequentially through the imaged volume. Radiologists rated the masses in each display (3D, 2D and videotapes) on a scale of 1 to 5 (5 = most suspicious) for each of six conventional gray-scale and six new vascular criteria. Thirteen masses proved to be benign and 11 were malignant. 3D provided a stronger subjective appreciation of vascular morphology and allowed somewhat better ultrasound discrimination of malignant masses than did the 2D images or videotapes (specificities of 85%, 79% and 71%, respectively, at a sensitivity of 90%). Only in 3D did the vascularity measures display a trend towards significance in this small study.

Biopsy↗
PubMed1997

Power Doppler: it's a good thing.

Power Doppler is a new method of ultrasound flow imaging the utility of which is currently under investigation. This technique creates a flow map based on the integrated power of the Doppler spectrum, rather than mean Doppler frequency. Power Doppler imaging is inherently more sensitive in terms of flow detection than standard color Doppler imaging; therefore, power Doppler can display flow for situations in which color Doppler is ineffective and can even display tissue perfusion in highly vascular organs such as the kidneys. Furthermore, power Doppler is not effected by aliasing, nor is it effected by blooming in the same way as color Doppler, which has deleterious effects on color Doppler flow images. The control of blooming with power Doppler may be of great importance in the clinical application of echo-enhancing agents. This review article discusses in detail the technological advantages and disadvantages of power Doppler flow imaging. In addition, it provides a synopsis of the preliminary research studies that have been conducted to date with respect to the clinical applications of power Doppler.

Animals↗
PubMed1997

Use of intravenous contrast material in transcranial sonography.

RATIONALE AND OBJECTIVES: The appearance of the intracranial vasculature was compared on power and color Doppler ultrasound (US) scans obtained with and without a microbubble contrast agent. MATERIALS AND METHODS: Nine patients (three men, six women) aged 42-70 years (mean age, 53 years) participated in the study. Seven patients underwent both color Doppler US and power Doppler US before and after intravenous administration of contrast agent, and two underwent only color Doppler US. All patients had previously undergone cerebral angiography. RESULTS: Before contrast material was administered, power Doppler US was more sensitive than color Doppler US in the detection of intracranial vessels (P < .05); neither technique depicted the entire circle of Willis in eight of nine patients. Postcontrast power Doppler US depicted more vascular segments than postcontrast color Doppler US (P < .01) or precontrast power Doppler US (P < .01). Use of intravenous contrast material enabled the entire circle of Willis to be evaluated from a single temporal bone acoustic window with both power Doppler US and color Doppler US in all patients. Contrast-enhanced power Doppler US depicted vessels not shown by enhanced color Doppler US. CONCLUSION: Contrast-enhanced power Doppler US depicted more vessels, better demonstrated specific vascular segments, and provided better vascular definition of the intracranial vasculature than contrast-enhanced color Doppler US or unenhanced power Doppler US.

Adult↗