Clinical and experimental studies of intraoperative autotransfusion using a new filtration device

The Haemocell S-350 device has recently been introduced for intraoperative autotransfusion. The system uses a novel membrane filter to process shed blood. In the first part of this study a 0.2-micron pore size filter was used in a randomized trial comparing the use of autotransfusion (n = 8) with bank blood controls (n = 9) during aortic reconstruction. This part of the trial was abandoned because of unexpected non-surgical bleeding. Bank blood requirements fell from a median of 3.0 (range 0.0-9.0) units to 1.5 (range 0.0-7.0) units when autotransfusion was used, but these patients had a greater perioperative blood loss (1791 (range 932-3104) versus 1140 (range 440-3840) ml). There was evidence of postoperative heparin excess with an activated partial thromboplastin time ratio of 1.3 (range 0.9-3.0) versus 1.0 (range 1.0-1.2) in controls and an activated clotting time of 206 (range 143-280) versus 137 (range 107-142) s. This was confirmed by raised plasma heparin levels and a prolonged thrombin time normalized by protamine. To improve performance a 0.6-micron pore size filter was studied in ten patients. Filtration efficiency doubled from 19 to 38 per cent. Electron micrographs demonstrated better filter clearance, but 44 per cent of the original concentration of heparin remained in the reinfusate. The S-350 device may be an attractive alternative to centrifugation for intraoperative autotransfusion but, until efficiency is improved, it should only be used for cardiovascular surgery when excess heparin can be reversed with protamine.     

Estimation of impurity profiles of drugs and related materials: part 19: theme with variations. Identification of impurities in 3-oxosteroids

Due to the varied reactions leading to the 3-oxo group in steroids and the reactivity of its environment, a large number of impurities related to this group are formed during the reaction steps and the degradation studies. In this paper the experiences from the authors laboratory with the 3-oxo-related impurities in 19-nor-4-ene-3-oxosteroids (norgestrel, norethisterone, nandrolone, its esters and Nestorone) as well as corticosteroids (prednisolone, mazipredone, etc) are presented. The impurities include saturated 3-ones, 1-ene-3-ones, 5(10)-ene-3-ones, 3-deoxo and 3-ethinyl-3,5-diene derivatives, 6-ene, 8(14)-ene, 6,8(14)-diene, 6-hydroxy (alpha and beta), 10beta-hydroxy and 6-one derivatives in 4-ene-3-oxosteroids and 8(9)-ene, 9(11)-ene, 11alpha-hydroxy, 11-oxo and 4-ene-3-one derivatives in 11beta-hydroxy-1,4-diene-3-oxosteroids. The chromatographic, spectroscopic and hyphenated techniques used in this study include TLC, GC, HPLC with diode array UV detector, GC-MS, LC-MS and NMR methods.     

The first measurement of an absolute surface concentration of reaction intermediates in ethylene hydrogenation

The first measurement of a turnover rate with respect to surface intermediate concentration in a high pressure heterogeneous catalytic reaction is reported. By using infrared-visible sum frequency generation to study the hydrogenation of ethylene on Pt(111), it was found that the surface concentration of -bonded ethylene, the key reaction intermediate, represented approximately 4% of a monolayer. Thus the absolute turnover rate per surface adsorbed ethylene molecule is 25 times faster than the rate measured per platinum atom. To explain these results, we propose a model of weakly adsorbed ethylene intermediates reacting on atop sites.     

Jordan surfaces in simply connected digital spaces

Certain tasks in multidimensional digital image analysis, in particular surface detection and volume estimation, lead us to the study of surfaces in the digital environment. It is desirable that these surfaces should have a Jordan property analogous to that of simple closed curves in two dimensions-namely, that they should partition the underlying space into an inside and an outside which are disconnected from each other. A version of this property, called near-Jordanness, has been previously defined and has been shown to be useful within a general theory of surfaces in digital spaces. The definition of a near-Jordan surface is global: it demands that all paths from the interior to the exterior cross the surface. This makes it difficult in many practical applications to check whether surfaces are near-Jordan. The work reported in this paper is motivated by the desire for a local condition, such that if a surface satisfies this condition at each of its elements, then it is guaranteed to be near-Jordan. In the search for such a condition, we were led to a concept of simple connectedness of a digital space, which resembles simple connectedness in ordinary topological spaces. We were then able to formulate the desired local condition for simply connected digital spaces. Many digital spaces, in particular those based on the commonly-studied tessellations of n-dimensional Euclidean space, are shown to be simply connected and thus our theory yields general sufficient conditions for boundaries in binary pictures to be near-Jordan.     

Common coupling and pointer variables,with application to a Linux case study

Both common coupling and pointer variables can exert a deleterious effect on the quality of software. The situation is exacerbated when global variables are assigned to pointer variables, that is, when an alias to a global variable is created. When this occurs, the number of global variables increases, and it becomes considerably harder to compute quality metrics correctly. However, unless aliasing is taken into account, variables may incorrectly appear to be unreferenced (neither defined nor used), or to be used without being defined. These ideas are illustrated by means of a case study of common coupling in the Linux kernel.

Manipulation of mental models of anatomy in interventional radiology and its consequences for design of human–computer interaction

Interventional radiology procedures require extensive cognitive processing from the physician. A set of these cognitive functions are aimed to be replaced by technology in order to reduce the cognitive load. However, limited knowledge is available regarding mental processes in interventional radiology. This research focuses on identifying mental model–related processes, in particular during percutaneous procedures, useful to improve image guidance during interventions. Ethnographic studies and a prototype-based study were conducted in order to perform a task analysis and to identify working strategies and cognitive processes. Data were compared to theories from visual imagery. The results indicate a high level of complexity of mental model construction and manipulation, in particular when mentally comparing mental model knowledge with radiology images on screen (e.g., to steer a needle correctly). Regarding current interface support, most difficult is the interpretation and selection of oblique views. New interface principles are needed to bring cognitive demands within reasonable human range, and also accompanying cognitive work strategies should be developed.     

Effects of β-α transformation on the static and dynamic tensile behavior of isotactic polypropylene

It was demonstrated that the mechanical stress-induced βα-transformation in isotactic polypropylene (iPP) is associated with considerable toughness enhancement. This toughness improvement depends on the test conditions (loading frequency). The toughness of β-iPP was superior to the α-iPP by 13% under static (characterized by a load frequency of ca. 5 × 10⁻⁴ Hz) and 70% under dynamic (tensile impact with a loading frequency in the range of ca. 3 × 10²…10³ Hz) conditions, respectively. By applying the essential work of fracture (EWF) concept to single-edge notched tensile (SEN-T) specimens it was shown that for the toughness upgrading observed, energy dissipation in the enlarged plastic zone is responsible. The occurrence of the βα-transformation was evidenced by differential scanning calorimetry (DSC). Based on DSC measurements it was found that the degree of βα-trans-formation depends on the local strain. At high strain values the βα-conversion is complete (at elogation at break in uniaxial static tensile test), while this transformation is only partial at lower strains (at tensile impact). In addition, in the plastic (or deformation) zone the βα-conversion changed locally, and can be used for mapping of this region. © 1996 John Wiley & Sons, Inc.     

PACAP-38 and PAC1 Receptor Alterations in Plasma and Cardiac Tissue Samples of Heart Failure Patients

Pituitary adenylate cyclase activating polypeptide-38 (PACAP-38) is a multifunctional neuropeptide, which may play a role in cardioprotection. However, little is known about the presence of PACAP-38 in heart failure (HF) patients. The aim of our study was to measure the alterations of PACAP-38 like immunoreactivity (LI) in acute (n = 13) and chronic HF (n = 33) and to examine potential correlations between PACAP-38 and HF predictors (cytokines, NT-proBNP). Tissue PACAP-38 LI and PAC1 receptor levels were also investigated in heart tissue samples of patients with HF. Significantly higher plasma PACAP-38 LI was detected in patients with acute HF, while in chronic HF patients, a lower level of immunoreactivity was observed compared to healthy controls (n = 13). Strong negative correlation was identified between plasma PACAP-38 and NT-proBNP levels in chronic HF, as opposed to the positive connection seen in the acute HF group. Plasma IL-1 β, IL-2 and IL-4 levels were significantly lower in chronic HF, and IL-10 was significantly higher in patients with acute HF. PACAP-38 levels of myocardial tissues were lower in all end-stage HF patients and lower PAC1 receptor levels were detected in the primary dilated cardiomyopathy group compared to the controls. We conclude that PACAP-38 and PAC1 expression correlates with some biomarkers of acute and chronic HF; therefore, further studies are necessary to explore whether PACAP could be a suitable prognostic biomarker in HF patients.