Tissue fixation security in transosseous rotator cuff repairs: a mechanical comparison of simple versus mattress sutures

The primary purpose of this investigation was to compare tissue fixation security by simple sutures versus mattress sutures in transosseous rotator cuff repair. These two repair techniques were each performed in 17 human cadaver shoulders, with two bone tunnels being used for the repair by two simple sutures and two other bone tunnels being used for the repair by one mattress suture. The repairs were loaded to failure in a servohydraulic materials test system. Rotator cuff repair by simple sutures was found to be significantly stronger than repair by mattress sutures (P = .0007). The average ultimate load to failure for the simple suture construct (189.62 N) was 39.72% greater than that for the mattress suture construct (135.71 N). Most of the failures occurred by suture breakage at the knot. Load-sharing by multiple suture tails and multiple knots in the simple suture configuration likely contributed to its superior strength characteristics compared with the mattress suture configuration.     

Activated partial thromboplastin time and outcome after thrombolytic therapy for acute myocardial infarction: results from the GUSTO-I trial

BACKGROUND: Although intravenous heparin is commonly used after thrombolytic therapy, few reports have addressed the relationship between the degree of anticoagulation and clinical outcomes. We examined the activated partial thromboplastin time (aPTT) in 29,656 patients in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) trial and analyzed the relationship between the aPTT and both baseline patient characteristics and clinical outcomes. METHODS AND RESULTS: Intravenous heparin was administered as a 5000-U bolus followed by an initial infusion of 1000 U/h, with dose adjustment to achieve a target aPTT of 60 to 85 seconds. aPTTs were collected 6, 12, and 24 hours after thrombolytic administration. Higher aPTT at 24 hours was strongly related to lower patient weight (P < .00001) as well as older age, female sex, and lack of cigarette smoking (all PT< .0001). At 12 hours, the aPTT associated with the lowest 30-day mortality, stroke, and bleeding rates was 50 to 70 seconds. There was an unexpected direct relationship between the aPTT and the risk of subsequent reinfarction. There was a clustering of reinfarction in the first 10 hours after discontinuation of intravenous heparin. CONCLUSIONS: Although the relationship between aPTT and clinical outcome was confounded to some degree by the influence of baseline prognostic characteristics, aPTTs higher than 70 seconds were found to be associated with higher likelihood of mortality, stroke, bleeding, and reinfarction. These findings suggest that until proven otherwise, we should consider the aPTT range of 50 to 70 seconds as optimal with intravenous heparin after thrombolytic therapy.     

Microphase structure and calculations of the interphase in poly (styrene-b-methylphenylsiloxane) diblock copolymers: a comparative study from small-angle X-ray scattering,electron spectroscopic imaging and solid-state nuclear magnetic resonance

The microphase structure of a series of poly (styrene-b-methylphenylsiloxane) (PS-b-PMPS)-diblock copolymers with various compositions and molecular weights has been studied by small-angle X-ray scattering, electron spectroscopic imaging and solid-state nuclear magnetic resonance spectroscopy. This diblock copolymer system is miscible within a distinct range of temperature and molecular weight exhibiting an upper critical solution temperature. The three chosen methods which complement each other can be applied to the chemically unmodified model system. The results of the various measurements correlate to describe the microphase structure, the domain size and the interphase.     

Influence of Threshold Stress on the Estimation of the Weibull Statistics

The influence of threshold stress on the estimation of the Weibull statistics is discussed in terms of the Akaike information criterion. Numerical simulations show that, if sample data are limited in number and threshold stress is not too large, the two-parameter Weibull distribution is still a preferred choice. For example, the fit of strength data of glass and ceramics to the two- and three-parameter Weibull distributions is compared.     

Rail-to-rail amplifier input stage with constant g/sub m/ and commonmode elimination

A new scheme for achieving rail-to-rail input to an amplifier is introduced. Constant g/sub m/ and common mode removal is obtained by using a single input differential pair and tunable DC level shifters via multiple input floating gate transistors. The feedback circuitry basically fixes the common mode of the amplifier, resulting in consistent and stable operation for rail-to-rail inputs and a high common mode rejection ratio.     

Intermodality, retrospective image registration in the thorax

The purpose of this study was to develop an accurate, retrospectively applicable procedure for registering thoracic studies from different modalities in a short amount of time and with minimal operator intervention. METHODS: CT and PET studies were acquired from six patients. The pleural surfaces in both image sets were determined by segmenting based on 50% of the maximum soft-tissue value in the study. These surfaces were converted into three-dimensional volumes and used to register the CT and PET studies in three dimensions using a sum of least squares fitting approach. The registered PET study was then displayed in a hot metal scale overlayed on top of the gray scale CT study. The accuracy of the fit was evaluated through a phantom study and preliminary clinical evaluation. RESULTS: A phantom study was performed to determine the limits of this technique. The accuracy was determined to be less than 2.3 mm in the x and y direction and 3 mm in the z direction. Preliminary clinical evaluation was also performed with encouraging results. CONCLUSION: This technique accurately registers PET and CT images of the thorax, retrospectively, without the need for external fiducial markers or other a priori action.     

Does Physiological Blood Glucose Control Require an Adaptive Control Strategy?

To test the hypothesis that only an adaptive algorithm would guarantee optimal feedback control of glycemia in insulin-dependent diabetes, fasting chronically diabetic dogs at rest were subjected to short-term artificial beta cell treatment. Insulin was applied intravenously and an oral glucose load was given during the experiment. Employing the same dosing algorithm, three different control strategies were employed in a random order on different days: adaptive control (minimum variance controller, Test A), fixed command control using on-line parameter estimates (Test B), and fixed command control using off-line individually optimized dosage constants (Test C). Comparison was made to nondiabetic control animals. The glycemic profiles were entirely normal in Test A and C, but were distinctly elevated in Test B. The peripheral hyperinsulinaemia could, however, not be avoided by adaptive control. It is concluded that the restoration of physiological blood glucose control in insulin-dependent diabetes requires dosage parameters which are either continually adapted to the actual situation (adaptive control) or are optimized to meet the individual's needs. In the latter case, fixed command control may be employed. Peripheral hyperinsulinaemia cannot be avoided as long as insulin is administered by a posthepatic route.     

A prospective study of multiple needle biopsies versus a single open biopsy for testicular sperm extraction in men with non-obstructive azoospermia

To identify the predictive factors for testicular sperm extraction (TESE) and to understand the pathology associated with TESE, we carried out a prospective study in 40 consecutive men with azoospermia due to primary gonadal failure. The main outcome measure was the retrieval of at least one testicular spermatozoon. Endocrine and biophysical profiles, testicular histology, Johnsen score and testicular spermatids were used as predictors of sperm extraction. Spermatogenesis was quantified with the Johnsen score. A variable pattern of spermatogenesis was common, being present in 20 (50%) patients. Visualisation of testicular spermatids on testicular histology showed a strong association with TESE (P < 0.0001). Statistically significant differences were detected in plasma follicle stimulating hormone (FSH) and testicular volume between patients who had hypospermatogenesis and Sertoli cell-only or maturation arrest. There were no significant differences in Johnsen score, biophysical and endocrine profiles between the groups with successful and failed TESE. However, a statistically significant trend occurred with changes in histological pattern [chi2 for trend, P = 0.001; Pearson's coefficient (r) = 0.6], Johnsen score (P = 0.022; r = 0.5), testicular volume (P = 0.01; r = 0.5) and plasma FSH concentrations (P = 0.044; r = 0.4), albeit to a limited degree. Difference in the interpretation of histological patterns with different assessors was observed. The type of occupation or risk factors for azoospermia showed no association with testicular pathology or TESE. Variable histological patterns in different tubules in the same individual may explain the poor correlation of TESE with endocrine and biophysical profiles, Johnsen score and histological pattern. Differences in the amount of tissue used for TESE and histopathology, and misinterpretation of testicular histology rather than failure to quantify spermatogenesis may explain the poor correlation between histological patterns and TESE. Testicular spermatids predicted TESE. However, considerable overlap in values means that no single variable can provide a perfect discrimination between the groups with successful and failed TESE.