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Biomedical subjects

S Deutsch

Publications and source records attributed to S Deutsch.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Immunoreactive plasma estrogens and vaginal hormone cytology in postmenopausal women.

The vaginal hormone cytology and the serum estrogen levels (as determined by radioimmunoassay) of 39 post-menopausal patients were compared. All cytologic parameters showed high statistical correlations with radioimmunoassay values, but these general associations could not be applied to individual patients. A more detailed analysis showed that an atrophic smear (eg, karyopyknotic index [KI], < 10%; parabasal level, > 20%; maturation value [MV], < 40%) indicate estrogen deficiency in the postmenopause. When the KI is 20%-40%, the parabasal cells less than 20% or the MV 40%-60%, the evaluation of estrogen status, on the basis of hormone cytology alone, is indeterminate. The three cytologic indices studied seem much more useful for detecting estrogen deficiency than estrogen excess in the postmenopause. The fact that immunochemical characteristics are not always related to biologic behavior must also be considered when interpreting these findings.

Estrogens↗
PubMedDate not supplied

Mean flow velocity patterns within a ventricular assist device.

A laser Doppler anemometry system was used to measure fluid velocities at 127 locations within a plexiglas model of the 70 cm3 Penn State electric ventricular assist device (VAD) fitted with Bjork-Shiley convexo-concave tilting disk valves. The velocity measurements were made using a seeded blood analog fluid that matched the kinematic viscosity of blood and the refractive index of plexiglas. At each location, 250 instantaneous velocity realizations were collected at eight instances during the pump cycle. The data were filtered and averaged to calculate mean (ensemble averaged) velocities. The results indicate that the largest mean velocities are created during systole in the VADs outlet tract, and during diastole in the major orifice of the mitral valve. A single vortex centered roughly about the axis of the cylindrical portion of the pump is created during early diastole. This vortex, which persists into early systole, provides good washing of the VAD walls. However, it does appear to impede the flow entering the VAD through the minor orifice of the mitral valve. High velocities also occur during diastole along the minor orifice wall of the outlet tract and are directed into the chamber. These retrograde velocities suggest the presence of a regurgitant jet near the wall of the prosthetic valve.

Blood Flow Velocity↗
PubMedDate not supplied

In vivo observation of cavitation on prosthetic heart valves.

In this study, a method to determine the existence of prosthetic heart valve cavitation in vivo is presented. Pennsylvania State University Left Ventricular Assist Devices (LVADs) were implanted in two separate calves for this study. Björk-Shiley Monostrut (Irvine, CA) 27 mm and 25 mm valves with Delrin occluders were used in the mitral and aortic positions, respectively. A high fidelity, piezoelectric pressure transducer was mounted approximately 1.25 cm proximal to the mitral valve and measured the high frequency pressure fluctuations caused by cavitation bubble formation and collapse after valve closure. The root mean square (RMS) value of the mitral pressure signal during a 5 ms interval after valve closure was used as a measure of cavitation intensity. The pressure signals observed in vivo were similar to ones observed in vitro with the same type of pressure transducer and were associated with the visually observed cavitation. The percentage of beats with cavitation increased from 20.3% to 67.7% when pump filling was decreased by increasing beat rate. A blood test conducted during post-operative days 1-3 showed a significant increase in plasma hemoglobin during the low filling condition. However, blood tests conducted later (post-operative days 7-44) did not show a significant change in plasma hemoglobin during low filling conditions.

Animals↗
PubMedDate not supplied

Mean velocity and Reynolds stress measurements in the regurgitant jets of tilting disk heart valves in an artificial heart environment.

Laser Doppler velocimetry, with a high temporal resolution (1 ms time windows), was used to measure the flow field in two regions (major and minor orifices) near the aortic and mitral valves (Bjork Shiley monostrut Nos. 25 and 27, respectively) of the Penn State artificial heart. The motion of each valve was also investigated using a 1000 frame/s video camera in order to estimate the valve's closing velocity. Fluid velocities in excess of and opposite to valve closing velocity were detected near the valve, providing evidence of "squeeze flow." Maximum Reynolds shear stresses of approximately 20,000 dyn/cm2 and time-averaged Reynolds shear stresses of approximately 2000 dyn/cm2 were observed during the regurgitant flow phase. These elevated Reynolds shear stresses suggest that regurgitant jets play a role in the hemolysis and thrombosis associated with tilting disk heart valves in an artificial heart environment.

Aortic Valve↗
PubMedDate not supplied

Comparison of the adrenocorticotropic hormone stimulation test in the follicular and luteal phases of the menstrual cycle.

A comparison was made of the ACTH stimulation test in the proliferative and luteal phases of the menstrual cycle in 13 subjects, each of whom served as her own control. The test yielded a 53.9% false-positive rate in the luteal phase. The study, therefore, clearly shows that from a practical, clinical point of view, the test is completely unreliable in the luteal phase, and is only valid when carried out in the follicular phase of the cycle.

17-alpha-Hydroxyprogesterone↗
PubMedDate not supplied

Mean velocities and Reynolds stresses within regurgitant jets produced by tilting disc valves.

Fluid velocities were measured with a two-component laser Doppler anemometry system in the regurgitant jet regions of Bjork-Shiley Delrin monostrut tilting disc valves mounted within a Plexiglas model of the 70 cm3 Penn State electric left ventricular assist device. At each measurement location, 250 instantaneous velocity realizations were collected at times when regurgitation through the valves occurred. The maximum Reynolds shear and normal stresses were calculated after filtering the data. Results show that Reynolds shear and normal stresses proximal to the mitral valve were elevated to magnitudes of 9,000 dynes/cm2 and 20,000 dynes/cm2, respectively. The peak Reynolds stresses near the mitral valve occurred during early systole, when regurgitant jet velocities reached magnitudes as high as 440 cm/sec. The Reynolds shear and normal stresses proximal to the aortic valve reached magnitudes of 9,900 dynes/cm2 and 20,500 dynes/cm2, respectively. The peak Reynolds stresses near the aortic valve occurred during early diastole, when regurgitant jet velocities were as high as 280 cm/sec. These high Reynolds stresses created by turbulent regurgitant flow have the potential to cause significant blood damage.

Aortic Valve↗
PubMedDate not supplied

Real-time in vitro observation of cavitation in a prosthetic heart valve.

A technique for real-time in vitro observation of cavitation on a prosthetic heart valve operating in a ventricular assist device under normal physiologic conditions has been developed. Considering the documented observation of cavitation erosion in heart valve components from human explants, and the potential risk of blood damage that cavitation presents, the technique developed in this study may prove useful in the design of prosthetic heart valves and ventricular assist devices. Cavitation of a glycerol blood analog fluid has been documented for a Medtronic/Hall prosthetic heart valve operating in a Penn State Electric Ventricular Assist Device. The ventricular assist device was operated in a mock circulatory system under normal physiologic conditions. The valve was located in the mitral position, with the cavitation occurring on the inlet side after valve closure. Bubble cavitation was seen on the valve occluder face, and vortex cavitation was observed at two locations in the vicinity of the valve occluder and housing. The cavity growth and collapse cycle for these forms of vaporous cavitation was less than 1 msec. Stroboscopic photography and stroboscopic videography with frame grabbing were used to document the cavity life cycle. With beat rate held constant, the cavity duration time was found to decrease with increasing mean venous return pressure.

Heart Valve Prosthesis↗
PubMedDate not supplied

Estimation of Reynolds stresses within the Penn State left ventricular assist device.

Fluid velocities were measured using a two-component laser Doppler anemometery (LDA) system at 129 locations within a Plexiglas model of a 70 cm3 Penn State electric Left Ventricular Assist Device (LVAD). The LVAD was driven by a pulsatile piston pump acting on an attached segmented polyurethane diaphragm. Bjork-Shiley tilting disc valves were used to provide unidirectional flow through the inlet and outlet ports. A seeded blood analog fluid, which matched the kinematic viscosity of blood at high shear rates and the refractive index of Plexiglas, was used to make the measurements. At each location, 250 instantaneous velocity realizations were collected at eight instances during the pump cycle. The maximum Reynolds shear and normal stresses were calculated for each pump cycle time and location after filtering the data. The results reveal that the highest Reynolds shear and normal stresses occur in the near wall region just proximal to the aortic valve during diastole, and reach values of 5,300 dynes/cm2 and 10,800 dynes/cm2, respectively. The elevated turbulent stresses are observed during the period of regurgitant flow through the aortic valve, with peak stress values arising during the period of peak regurgitant flow. This supports the hypothesis that a regurgitant turbulent jet is formed near the wall of the prosthetic aortic valve and may be contributing to blood damage.

Blood Flow Velocity↗
PubMedDate not supplied

Perimenopausal bleeding patterns and pathologic findings.

The charts of 500 sequential perimenopausal patients were reviewed and their alterations in menstrual flow were characterized as fitting one of three patterns. Sixty-two patients (12%) had sudden amenorrhea, 347 (70%) had oligomenorrhea and/or hypomenorrhea, and 91 (18%) had menorrhagia, metrorrhagia, and/or hypermenorrhea. All of the patients in the menorrhagia/metrorrhagia and/or hypermenorrhea group had histologic evaluations to rule out the presence of premalignant or malignant disease; 17 women (19%) in this group had premalignant or malignant findings. In addition, 4 of the 5 women with malignancies had intermenstrual bleeding. Of the 9 women in the study with intermenstrual bleeding, 4 had invasive cancer and 2 had endometrial hyperplasia. This study documents and highlights the high incidence of premalignant and malignant findings in perimenopausal patients with bleeding patterns other than amenorrhea or oligomenorrhea/hypomenorrhea, and underscores the need for perimenopausal women with menorrhagia, metrorrhagia, and/or hypermenorrhea to undergo thorough evaluation.

Age Factors↗