Active renin versus plasma renin activity to define aldosterone-to-renin ratio for primary aldosteronism

BACKGROUND: In recent years, the assessment of the plasma aldosterone-to-renin ratio (ARR) has become an established screening method for the diagnosis of primary aldosteronism. Plasma renin activity (PRA) is usually measured to define ARR although, increasingly, renin concentration alone is often measured in clinical routine. OBJECTIVE: To determine the threshold of ARR using active renin concentration to screen for primary aldosteronism. DESIGN AND PARTICIPANTS: To determine the ARR threshold based on plasma immunoreactive renin concentration (irR), we measured plasma aldosterone concentration (PAC), irR and PRA in 36 hypertensive patients, nine thereof with adrenal adenoma, and compared ARRs calculated from irR and PRA, respectively. SETTING: Single-centre, hypertension clinic in a tertiary care hospital. RESULTS: PRA ranged from 0.41-14.9 ng/ml per h and irR from 1.1-72 ng/l. There was an excellent correlation between PRA and irR (r = 0.98, P < 0.0001) and between ARRPRA and ARRirR (r = 0.96, P < 0.0001). An ARRPRA > 750 pmol/l per ng/ml per h was previously found to be highly predictive of primary aldosteronism because 90% of the corresponding patients failed to suppress PAC upon saline infusion or fludrocortisone. The corresponding threshold value for ARRirR was 150 pmol/ng in our patients. Using these cut-offs, nine subjects had both increased ARRPRA and ARRirR while, in three patients, either ARRPRA or ARRirR were increased. The nine patients with increased ARRPRA and ARRirR also had PAC > 650 pmol/l. Only these patients had adrenal adenomas. CONCLUSIONS: The ARR threshold to screen for primary aldosteronism may be based on measurement of irR. An ARRirR > 150 pmol/ng may indicate primary aldosteronism.

Soft tissue dehiscence coverage around endosseous implants: a prospective cohort study

AIM: To evaluate the healing outcome of soft tissue dehiscence coverage at implant sites. MATERIAL AND METHODS: Ten patients with one mucosal recession defect at an implant site and a contralateral unrestored clinical crown without recession were recruited. The soft tissue recessions were surgically covered using a coronally advanced flap in combination with a free connective tissue graft. Healing was studied at 1, 3 and 6 months post-operatively. RESULTS: Soft tissue dehiscences were covered with a coronal overcompensation of the flap margin up to 1.2 mm after the procedure. After 1 month, the coverage shrank to a mean of 75%, after 3 months to 70% and after 6 months to 66%. CONCLUSIONS: The implant sites revealed a substantial, clinically significant improvement following coronal mucosal displacement in combination with connective tissue grafting, but in none of the sites, a could complete implant soft tissue dehiscence coverage be achieved.

Femoral morphology differs between deficient and excessive acetabular coverage

Structural deformities of the femoral head occurring during skeletal development (eg, Legg-Calvé-Perthes disease) are associated with individual shapes of the acetabulum but it is unclear whether differences in acetabular shape are associated with differences in proximal femoral shape. We questioned whether the amount of acetabular coverage influences femoral morphology. We retrospectively compared the proximal femoral anatomy of 50 selected patients (50 hips) with developmental dysplasia of the hip (lateral center-edge angle [LCE] < or = 25 degrees ; acetabular index > or = 14 degrees ) with 45 selected patients (50 hips) with a deep acetabulum (LCE > or = 39 degrees ). Using MRI arthrography we measured head sphericity, epiphyseal shape, epiphyseal extension, and femoral head-neck offset. A deep acetabulum was associated with a more spherical head shape, increased epiphyseal height with a pronounced extension of the epiphysis towards the femoral neck, and an increased offset. In contrast, dysplastic hips showed an elliptical femoral head, decreased epiphyseal height with a less pronounced extension of the epiphysis, and decreased head-neck offset. Hips with different acetabular coverage are associated with different proximal femoral anatomy. A nonspherical head in dysplastic hips could lead to joint incongruity after an acetabular reorientation procedure. LEVEL OF EVIDENCE: Level IV, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence.

Torque converter turbine noise and cavitation noise over varying speed ratio

These investigations will discuss the operational noise caused by automotive torque converters during speed ratio operation. Two specific cases of torque converter noise will be studied; cavitation, and a monotonic turbine induced noise. Cavitation occurs at or near stall, or zero turbine speed. The bubbles produced due to the extreme torques at low speed ratio operation, upon collapse, may cause a broadband noise that is unwanted by those who are occupying the vehicle as other portions of the vehicle drive train improve acoustically. Turbine induced noise, which occurs at high engine torque at around 0.5 speed ratio, is a narrow-band phenomenon that is audible to vehicle occupants currently. The solution to the turbine induced noise is known, however this study is to gain a better understanding of the mechanics behind this occurrence. The automated torque converter dynamometer test cell was utilized in these experiments to determine the effect of torque converter design parameters on the offset of cavitation and to employ the use a microwave telemetry system to directly measure pressures and structural motion on the turbine. Nearfield acoustics were used as a detection method for all phenomena while using a standardized speed ratio sweep test. Changes in filtered sound pressure levels enabled the ability to detect cavitation desinence. This, in turn, was utilized to determine the effects of various torque converter design parameters, including diameter, torus dimensions, and pump and stator blade designs on cavitation. The on turbine pressures and motion measured with the microwave telemetry were used to understand better the effects of a notched trailing edge turbine blade on the turbine induced noise.

MIMO waveform design using continuous phase modulation

Hybrid MIMO Phased-Array Radar (HMPAR) is an emerging technology that combines MIMO (multiple-in, multiple-out) radar technology with phased-array radar technology. The new technology is in its infancy, but much of the theoretical work for this specific project has already been completed and is explored in great depth in [1]. A brief overview of phased-array radar systems, MIMO radar systems, and the HMPAR paradigm are explored in this paper. This report is the culmination of an effort to support research in MIMO and HMPAR utilizing a concept called intrapulse beamscan. Using intrapulse beamscan, arbitrary spatial coverage can be achieved within one MIMO beam pulse. Therefore, this report focuses on designing waveforms for MIMO radar systems with arbitrary spatial coverage using that phenomenon. With intrapulse beamscan, scanning is done through phase-modulated signal design within one pulse rather than phase-shifters in the phased array over multiple pulses. In addition to using this idea, continuous phase modulation (CPM) signals are considered for their desirable peak-to-average ratio property as well as their low spectral leakage. These MIMO waveforms are designed with three goals in mind. The first goal is to achieve flexible spatial coverage while utilizing intrapulse beamscan. As with almost any radar system, we wish to have flexibility in where we send our signal energy. The second goal is to maintain a peak-to-average ratio close to 1 on the envelope of these waveforms, ensuring a signal that is close to constant modulus. It is desired to have a radar system transmit at the highest available power; not doing so would further diminish the already very small return signals. The third goal is to ensure low spectral leakage using various techniques to limit the bandwidth of the designed signals. Spectral containment is important to avoid interference with systems that utilize nearby frequencies in the electromagnetic spectrum. These three goals are realized allowing for limitations of real radar systems. In addition to flexible spatial coverage, the report examines the spectral properties of utilizing various space-filling techniques for desired spatial areas. The space-filling techniques examined include Hilbert/Peano curves and standard raster scans.

Implementation of a Variable Compression Ratio Mechanism in a Four Cylinder Engine

Ever since the invention of the internal combustion engine, generating more power and achieving better efficiency has been a major goal for the designers. Variable compression ratio technology is way to achieve those goals. This paper will discuss the method of varying the compression ratio of an inline 4-cylinder engine through the use of a 4-bar linkage and gear mechanism. This mechanism was proven to easily vary the compression ratio of the engine and shows promise of becoming a technology used for future engine designer.

[Coverage of pressure sores with free flaps]

INTRODUCTION: The coverage of recurrent pressure sores with unstable scar in the surrounding tissue is still an unsolved problem in the literature. Local and regional transfer of tissue often does not meet the requirements of the tissue deficit. Especially in recurrent pressure sores, the adjacent skin has already been consumed due to multiple surgeries. As a good alternative, the microsurgical transfer of flaps offers viable tissue to cover even large pressure sores. METHODS: We performed a total of six free flaps in five patients who suffered from intractable pressure sores in the hip region. The age of the patients was between 41 and 63 years. The defect size varied between 6 x 6 cm and 25 x 30 cm. Two combined myocutaneous scapula-latissimus dorsi, two myocutaneous latissimus dorsi, one anteromedial thigh, and one rectus femoris flap were used to cover the defects. RESULTS: The average follow-up time was 29 months. Flaps provided stable coverage in four of five patients at 12-month follow-up. There was one subtotal flap necrosis that was subsequently treated with split-thickness skin grafting. CONCLUSION: In this series of five patients with six free flaps, we were able to show that the microsurgical transfer of tissue is a valuable option in the treatment of difficult pressure sores. Even in older and debilitated patients, this method is a good alternative to conventional local flaps.