Smart instrumentation for determination of ligament stiffness and ligament balance in total knee arthroplasty.

Ligament balance is an important and subjective task performed during total knee arthroplasty (TKA) procedure. For this reason, it is desirable to develop instruments to quantitatively assess the soft-tissue balance since excessive imbalance can accelerate prosthesis wear and lead to early surgical revision. The instrumented distractor proposed in this study can assist surgeons on performing ligament balance by measuring the distraction gap and applied load. Also the device allows the determination of the ligament stiffness which can contribute a better understanding of the intrinsic mechanical behavior of the knee joint. Instrumentation of the device involved the use of hall-sensors for measuring the distractor displacement and strain gauges to transduce the force. The sensors were calibrated and tested to demonstrate their suitability for surgical use. Results show the distraction gap can be measured reliably with 0.1mm accuracy and the distractive loads could be assessed with an accuracy in the range of 4N. These characteristics are consistent with those have been proposed, in this work, for a device that could assist on performing ligament balance while permitting surgeons evaluation based on his experience. Preliminary results from in vitro tests were in accordance with expected stiffness values for medial collateral ligament (MCL) and lateral collateral ligament (LCL).

Peri-operative management of antiplatelet therapy in patients with coronary artery disease. Joint position paper by members of the working group on Perioperative Haemostasis of the Society on Thrombosis and Haemostasis Research (GTH), the working group on Perioperative Coagulation of the Austrian Society for Anesthesiology, Resuscitation and Intensive Care (ÖGARI) and the Working Group Thrombosis of the European Society for Cardiology (ESC).

An increasing number of patients suffering from cardiovascular disease, especially coronary artery disease (CAD), are treated with aspirin and/or clopidogrel for the prevention of major adverse events. Unfortunately, there are no specific, widely accepted recommendations for the perioperative management of patients receiving antiplatelet therapy. Therefore, members of the Perioperative Haemostasis Group of the Society on Thrombosis and Haemostasis Research (GTH), the Perioperative Coagulation Group of the Austrian Society for Anesthesiology, Reanimation and Intensive Care (ÖGARI) and the Working Group Thrombosis of the European Society of Cardiology (ESC) have created this consensus position paper to provide clear recommendations on the perioperative use of anti-platelet agents (specifically with semi-urgent and urgent surgery), strongly supporting a multidisciplinary approach to optimize the treatment of individual patients with coronary artery disease who need major cardiac and non-cardiac surgery. With planned surgery, drug eluting stents (DES) should not be used unless surgery can be delayed for ≥12 months after DES implantation. If surgery cannot be delayed, surgical revascularisation, bare-metal stents or pure balloon angioplasty should be considered. During ongoing antiplatelet therapy, elective surgery should be delayed for the recommended duration of treatment. In patients with semi-urgent surgery, the decision to prematurely stop one or both antiplatelet agents (at least 5 days pre-operatively) has to be taken after multidisciplinary consultation, evaluating the individual thrombotic and bleeding risk. Urgently needed surgery has to take place under full antiplatelet therapy despite the increased bleeding risk. A multidisciplinary approach for optimal antithrombotic and haemostatic patient management is thus mandatory.

Visualization of aqueous shunt position and patency using anterior segment optical coherence tomography.

PURPOSE: To describe the use of anterior segment optical coherence tomography (AS-OCT) to clarify the position and patency of aqueous shunt devices in the anterior chamber of eyes where corneal edema or tube position does not permit a satisfactory view. DESIGN: Noncomparative observational case series. METHODS: Four cases are reported in which aqueous shunt malposition or obstruction was suspected but the shunt could not be seen on clinical examination. The patients underwent AS-OCT to identify the position and patency of the shunt tip. RESULTS: In each case, AS-OCT provided data regarding tube position and/or patency that could not be obtained by slit-lamp examination or by gonioscopy that influenced management. CONCLUSIONS: AS-OCT can be used to visualize anterior chamber tubes in the presence of corneal edema that precludes an adequate view or in cases where the tube is retracted into the cornea. In such cases, AS-OCT is useful in identifying shunt patency and position, which helps guide clinical decision making.

Sensitive bioassay for determination of fluconazole concentrations in plasma using a Candida albicans mutant hypersusceptible to azoles.

The antifungal agent fluconazole (FLC) is widely used in clinical practice. Monitoring FLC levels is useful in complicated clinical settings and in experimental infection models. A bioassay using Candida pseudotropicalis, a simple and cost-effective method, is validated only for FLC levels ranging from 5 to 40 mg/liter. An extension of the analytical range is needed to cover most yeast MICs. A new bioassay in RPMI agar containing methylene blue was developed using C. albicans DSY1024, a mutant rendered hypersusceptible to FLC constructed by the deletion of the multidrug efflux transporter genes CDR1, CDR2, CaMDR1, and FLU1. Reproducible standard curves were obtained with FLC concentrations in plasma ranging from 1 to 100 mg/liter (quadratic regression coefficient > 0.997). The absolute sensitivity was 0.026 microg of FLC. The method was internally validated according to current guidelines for analytical method validation. Both accuracy and precision lied in the required +/-15% range. FLC levels measured by bioassay and by high-performance liquid chromatography (HPLC) performed with 62 plasma samples from humans and rats showed a strong correlation (coefficients, 0.979 and 0.995, respectively; percent deviations of bioassay from HPLC values, 0.44% +/- 15.31% and 2.66% +/- 7.54%, respectively). In summary, this newly developed bioassay is sensitive, simple, rapid, and inexpensive. It allows nonspecialized laboratories to determine FLC levels in plasma to within the clinically relevant concentration range and represents a useful tool for experimental treatment models.

Sensitive determination of D-lactic acid and L-lactic acid in urine by high-performance liquid chromatography-tandem mass spectrometry.

D-lactic acid in urine originates mainly from bacterial production in the intestinal tract. Increased D-lactate excretion as observed in patients affected by short bowel syndrome or necrotizing enterocolitis reflects D-lactic overproduction. Therefore, there is a need for a reliable and sensitive method able to detect D-lactic acid even at subclinical elevation levels. A new and highly sensitive method for the simultaneous determination of L- and D-lactic acid by a two-step procedure has been developed. This method is based on the concentration of lactic acid enantiomers from urine by supported liquid extraction followed by high-performance liquid chromatography-tandem mass spectrometry. The separation was achieved by the use of an Astec Chirobiotic? R chiral column under isocratic conditions. The calibration curves were linear over the ranges of 2-400 and 0.5-100 µmol/L respectively for L- and D-lactic acid. The limit of detection of D-lactic acid was 0.125 µmol/L and its limit of quantification was 0.5 µmol/L. The overall accuracy and precision were well within 10% of the nominal values. The developed method is suitable for production of reference values in children and could be applied for accurate routine analysis.

Expérience de dix ans de réanimation chirurgicale d'un centre hospitalier universitaire. Détermination d'un critère d'identification des patients à risque de décéder de coagulopathie irréversible [10 years experience in surgical resuscitation at a university hospital center. Determination of a criterion for identifying patients at risk for fatal irreversible coagulopathy]

The authors evaluated ten years of surgical reanimation in the University Centre of Lausanne (CHUV). Irreversible coagulopathy (IC) is the predominant cause of death for the polytraumatized patient. Acidosis, hypothermy, and coagulation troubles are crucial elements of this coagulopathy. The authors looked for a criterion allowing the identification of dying of IC. In a retrospective study, laboratory results of pH, TP, PTT, thrombocyte count and the need for blood transfusion units were checked for each major step of the primary evaluation and treatment of the polytraumatized patients. These results were considered as critical according to criteria of the literature (30). The authors conclude that the apparation of a third critical value may be useful to identify the polytraumatized patient at risk of dying of IC status. This criterion may also guide the trauma team in selecting a damage control surgical approach (DCS). This criterion was then introduced into an algorithm involving the Emergency Department, the operating room and the Intensive Care Unit. This criterion is a new tool to address the patient at the crucial moment to the appropriate hospital structure.

Determination of Tension Crack Development in Plastic P.C. Concrete with Retarding Admixtures, MLR-86-12, 1987

Bridge deck cracking occasionally occurs during construction for any number of reasons. Improper design, concrete placement or deck curing can result in cracks. One contributing factor toward cracking may be dead load deflections induced during concrete placement. For both continuous and non-continuous bridges, specific placement sequences are required to minimize harmful deflections in previously placed sections. Set retarding admixtures are also used to keep previously placed concrete plastic until the pour is completed. The problem is--at what point does movement of the concrete cause permanent damage to the deck. The study evaluated the time to crack formation relationship for mixes with low and high dosages of set retarding admixtures currently approved for use in Iowa state and county projects.

Determination of the Optimum Base Characteristics for Pavements, TR-482, 2004

In recent years, it has become apparent that the design and maintenance of pavement drainage extends the service life of pavements. Most pavement structures now incorporate subsurface layers. Part of the function of these subsurface layers is to drain away excess water, which can be extremely deleterious to the life of the pavement. To assure the effectiveness of such drainage layers after they have been spread and compacted, simple, rapid, in-situ permeability and stability testing and end-result specification are needed. This report includes conclusions and recommendations related to four main study objectives: (1) Determine the optimal range for in-place stability and in-place permeability based on Iowa aggregate sources; (2) Evaluate the feasibility of an air permeameter for determining the permeability of open and well-graded drainage layers in situ; (3) Develop reliable end-result quality control/quality assurance specifications for stability and permeability; and (4) Refine aggregate placement and construction methods to optimize uniformity.

Gas-chromatography mass-spectrometry determination of phthalic acid in human urine as a biomarker of folpet exposure.

Agricultural workers are exposed to folpet, but biomonitoring data are limited. Phthalimide (PI), phthalamic acid (PAA), and phthalic acid (PA) are the ring metabolites of this fungicide according to animal studies, but they have not yet been measured in human urine as metabolites of folpet, only PA as a metabolite of phthalates. The objective of this study was thus to develop a reliable gas chromatography-tandem mass spectrometry (GC-MS) method to quantify the sum of PI, PAA, and PA ring-metabolites of folpet in human urine. Briefly, the method consisted of adding p-methylhippuric acid as an internal standard, performing an acid hydrolysis at 100 °C to convert ring-metabolites into PA, purifying samples by ethyl acetate extraction, and derivatizing with N,O-bis(trimethylsilyl)trifluoro acetamide prior to GC-MS analysis. The method had a detection limit of 60.2 nmol/L (10 ng/mL); it was found to be accurate (mean recovery, 97%), precise (inter- and intra-day percentage relative standard deviations <13%), and with a good linearity (R (2) > 0.98). Validation was conducted using unexposed peoples urine spiked at concentrations ranging from 4.0 to 16.1 μmol/L, along with urine samples of volunteers dosed with folpet, and of exposed workers. The method proved to be (1) suitable and accurate to determine the kinetic profile of PA equivalents in the urine of volunteers orally and dermally administered folpet and (2) relevant for the biomonitoring of exposure in workers.

Determination of Rumble Strip Effectiveness, HR-184, 1979

Rumble strips are patches of specially treated pavement surfaces which are designed to produce aural and tactile stimuli inside vehicles. The intent is to alert drivers and when desirable, cause them to slow down or come to a stop. Installations were made in a three-county area in Iowa to study rumble strip effectiveness as an accident reducing measure. The investigation of accidents at the various test sites showed that rumble strips were effective in reducing certain types of intersection accidents. Although no statistically significant effect of the saturation use was found on total accidents, there are indications that accidents may be reduced when used in low density i.e., rural type areas.

Cava (Spanish sparkling wine) aroma: composition and determination methods

Cava (Spanish sparkling wine) is one of the mostimportant quality sparkling wines in Europe. It is produced by thetraditional method in which a base wine is re-fermented and agedin the same bottle that reaches the consumer. The special ageing incontact with lees gives the cava a particular bouquet with toasty,sweet or lactic notes. These nuances could be related with thechemical composition of aroma. The methods required to analyzethe flavor of cava are revised. Three approaches are necessary toobtain a wider profile: chemical, olfactometric and sensory.

Evaluation of Rapid Determination of the Chloride Permeability of Portland Cement Concrete by AASHTO T277-83, MLR-86-11, 1987

An Iowa D.O.T. Laboratory built machine was constructed for the chloride permeability testing of concrete by measuring electric current through a specimen between a salt solution and a base solution. This study had two purposes. The first was to evaluate the machine's performance. To do this, three concrete mixes were made consisting of different cement factors and water/cement ratios. Each mix was tested for chloride ion content by the 90- day salt ponding method and for chloride permeability at a 28-day cure by the permeability machine. The results from each test were evaluated to see if there was correlation between chloride ion content and the chloride permeability. It was determined that there was a correlation and that the permeability machine was satisfactory for determining chloride permeability in concrete. The second purpose of this study was to examine the effects that pozzolans have on the chloride permeability of concrete. Four mixes were made: one without any pozzolans as a control, one with class C fly ash, one with class F fly ash, and one with silica fume. Specimens from each mix were evaluated for chloride ion content by the 90-day salt ponding test and by the laboratory built machine for chloride permeability after curing 28 days. Specimens from these mixes were also taken from the salt ponding slabs after completion of the ponding test to examine the effect chloride ion content has on the operation of the chloride permeability machine. Specimens containing pozzolans were also examined for chloride permeability after a cure of 180 days. It was determined that the addition of pozzolans to concrete lowers the chloride permeability as measured by the permeability machine. Class F fly ash and silica fume in the concrete had a major effect in lowering the chloride permeability in concrete as measured by the permeability machine.

Determination of Asphalt Content and Characteristics of Bituminous Paving Mixtures, MLR-88-11, 1988

Due to the hazardous nature of chemical asphalt extraction agents, nuclear gauges have become an increasingly popular method of determining the asphalt content of a bituminous mix. This report details the results of comparisons made between intended, tank stick, extracted, and nuclear asphalt content determinations. A total of 315 sets of comparisons were made on samples that represented 110 individual mix designs and 99 paving projects. All samples were taken from 1987 construction projects. In addition to the comparisons made, seventeen asphalt cement samples were recovered for determination of penetration and viscosity. Results were compared to similar tests performed on the asphalt assurance samples in an attempt to determine the amount of asphalt hardening that can be expected due to the hot mix process. Conclusions of the report are: 1. Compared to the reflux extraction procedure, nuclear asphalt content gauges determine asphalt content of bituminous mixes with much greater accuracy and comparable precision. 2. As a means for determining asphalt content, the nuclear procedure should be used as an alternate to chemical extractions whenever possible. 3. Based on penetration and viscosity results, softer grade asphalts undergo a greater degree 'of hardening due to hot mix processing than do harder grades, and asphalt viscosity changes caused by the mixing process are subject to much more variability than are changes in penetration. 4. Based on changes in penetration and viscosity, the Thin Film Oven Test provides a reasonable means of estimating how much asphalt hardening can be anticipated due to exposure to the hot mix processing environment.

Determination of the enantiomers of thioridazine, thioridazine 2-sulfone, and of the isomeric pairs of thioridazine 2-sulfoxide and thioridazine 5-sulfoxide in human plasma.

Thioridazine is a commonly prescribed phenothiazine drug administered as a racemate and it is believed that its antipsychotic effect is mainly associated with (R)-thioridazine. A method based on high-performance liquid chromatography has been developed for the determination of the enantiomers of thioridazine and thioridazine 2-sulfone (THD 2-SO2 or sulforidazine) and of the enantiomers of the diastereoisomeric pairs of thioridazine 2-sulfoxide (THD 2-SO or mesoridazine) and thioridazine 5-sulfoxide (THD 5-SO) in the plasma of thioridazine-treated patients. The method involves sequential achiral and chiral HPLC. The limits of quantitation for total (R) + (S) concentrations were found to be 15 ng/ml for thioridazine and 5 ng/ml for its metabolites. The limits for the determination of the (R)/(S) ratios were found to be 60 ng/ml for racemic THD and 10 ng/ml for racemic THD 2-SO, THD 2-SO2, THD 5-SO (FE) and THD 5-SO (SE). The method has been used to determine the concentrations of the enantiomers of thioridazine and of its metabolites in the plasma of a patient treated with 100 mg of racemic thioridazine hydrochloride per os per day for 14 days. The results show a high enantioselectivity in the metabolism of this drug: the (R)/(S) ratios for THD, THD 2-SO (FE), THD 2-SO (SE), THD 2-SO2, THD 5-SO (FE) and THD 5-SO (SE) were found to be 3.90, 1.22, 6.10, 4.10, 0.09 and 28.0, respectively.