Comparison of whole body versus thoracic bioimpedance in relation to ultrafiltration volume and systolic blood pressure during hemodialysis

In contrast to whole body bioimpedance, which estimates fluid status at a single point in time, thoracic bioimpedance applied by a wearable device could enable continuous measurements. However, clinical experience with thoracic bioimpedance in patients on dialysis is limited. To test the reproducibility of whole body and thoracic bioimpedance measurements and to compare their relationship with hemodynamic changes during hemodialysis, these parameters were measured pre- and end-dialysis in 54 patients during two sessions. The resistance from both bioimpedance techniques was moderately reproducible between two dialysis sessions (intraclass correlations of pre- to end-dialysis whole body and thoracic resistance between session 1 and 2 were 0.711 [0.58-0.8] and 0.723 [0.6-0.81], respectively). There was a very high to high correlation between changes in ultrafiltration volume and changes in whole body thoracic resistance. Changes in systolic blood pressure negatively correlated to both bioimpedance techniques. Although the relationship between changes in ultrafiltration volume and changes in resistance was stronger for whole body bioimpedance, the relationship with changes in blood pressure was at least comparable for thoracic measurements. These results suggest that thoracic bioimpedance, measured by a wearable device, may serve as an interesting alternative to whole body measurements for continuous hemodynamic monitoring during hemodialysis.NEW & NOTEWORTHY We examined the role of whole body and thoracic bioimpedance in hemodynamic changes during hemodialysis. Whole body and thoracic bioimpedance signals were strongly related to ultrafiltration volume and moderately, negatively, to changes in blood pressure. This work supports the further development of a wearable device measuring thoracic bioimpedance longitudinally in patients on hemodialysis. As such, it may serve as an innovative tool for continuous hemodynamic monitoring during hemodialysis in hospital or in a home-based setting.

Clinicopathological characteristics and disease chronicity in native kidney biopsies in Flanders

Background

The Flemish Collaborative Glomerulonephritis Group (FCGG) registry provides complete population data on kidney disease epidemiology in the region of Flanders (Belgium), as it captures all native kidney biopsies performed in its population of 6.5 million inhabitants.

Methods

From 2017 until 2019, 2054 adult kidney biopsies were included from 26 nephrology centers (one biopsy per patient). Data on nephrotic and nephritic syndrome were available in 1992 and 2026 biopsies, respectively. In a subgroup of 898 biopsies containing ≥10 glomeruli from 2018 to 2019, disease chronicity was graded using the Mayo Clinic Chronicity Score (MCCS). The association between clinical variables and MCCS was determined using simple and multiple linear regression models.

Results

Nephrotic syndrome (present in 378 patients, 19.0%) was most frequently caused by minimal change disease in younger patients (18-44 years), membranous nephropathy in older patients (45-74 years) and amyloidosis in the elderly (>75 years). Nephritic syndrome (present in 421 patients, 20.8%) was most frequently caused by immunoglobulin A nephropathy (IgAN) in younger patients (18-64 years) and ANCA-associated vasculitis (AAV) in older patients (>64 years). AAV and IgAN were the most frequent underlying diagnoses in biopsies in which crescents were identified. In multivariable analysis, acute and chronic kidney disease and diagnoses of diabetic kidney disease, nephrosclerosis and hyperoxaluria/hypercalcemic nephropathy were associated with the highest MCCS increases.

Conclusions

The FCGG registry validates data from previous Western European registries and provides a snapshot of disease chronicity in the whole biopsied Flemish population.

MO730THORACIC BIOIMPEDANCE AS AN INNOVATIVE TOOL TO DETECT CHANGES IN BLOOD PRESSURE DURING HEMODIALYSIS

Background and Aims

Blood pressure (BP) variability is an important cardiovascular risk factor that contributes to the high burden of cardiovascular mortality in hemodialysis (HD) patients. Ultrafiltration rate (UFR) and plasma refill rate modify the extracellular volume (ECV), which is a major determinant of the systolic BP. Segmental bioimpedance of the thoracic region addresses the central volume compartment of the body. We hypothesize that changes in bioimpedance reflect changes in BP and that thoracic measurements are more accurately in detecting intradialytic BP changes compared to whole body bioimpedance.

Method

During two consecutive short-term interval HD sessions, thoracic bioimpedance signal was registered continuously from predialysis until the end of the session. Corresponding BP, whole body bioimpedance and ultrafiltration volume (UFV) after the start and at the end of dialysis was registered. After outlier detection, valid raw bioimpedance data [Ohm] at 8 and 160 kHz for thoracic measurements, and 5 and 200 kHz for whole body measurements, were taken into further analysis. Dialysis sessions were divided into 3 groups according to the development of the systolic BP: a drop ≥ than 20 mmHg was defined as a hypotensive session, an increase ≥ 10 mmHg was considered as a hypertensive session. Pearson correlation analysis was applied (r, p-value) to the relative data, calculated as a percentage from the start value.

Results

From 2 dialysis centres, a total of 46 HD patients were enrolled in the study (65.2% male, mean age 71 ± 12.6 years, mean dialysis vintage 4 ± 3.9 years), which resulted in 89 dialysis sessions to analyse. Mean systolic BP after start of dialysis was 133.2 ± 20.7 mmHg and mean UF volume was 1817.5 ± 801.5 mL. 23 sessions showed a hypotensive gradient from the start till the end of dialysis, and 13 sessions progressed with an increase of more than 10 mmHg. When the 8 kHz curve was plotted according to the 3 BP groups, a more plane increase in thoracic bioimpedance signal was observed in the group with a normal tension course (Figure 1).

There was a significant relationship between UFR and changes in relative bioimpedance data, as well as thoracic (r = .49 at 8 kHz, r = .46 at 160 kHz, all ps < .001), as whole body bioimpedance (r = .58 at 5 kHz, r = .52 at 200 kHz, all ps < .001). UFV correlated with changes in systolic BP (r = -.31, p < .01). Both bioimpedance techniques correlated with each other (r = .38, p = .001 for low frequencies; r = .29, p < .01 for high frequencies). Where the relative thoracic bioimpedance signal correlated with changes in systolic BP (r = -.35 at 8kHz, -.32 at 160 kHz, all ps < .01) (Figure 2), whole body did not.

Conclusion

Thoracic bioimpedance is associated with intradialytic BP changes, whereas whole body bioimpedance is not. Thoracic bioimpedance has the potential to function as an important diagnostic and predictive tool in BP variability during HD.

MO829INSTITUTIONAL TRANSPORT AS RISK FACTOR FOR COVID-19 IN HEMODIALYSIS PATIENTS

Background and Aims

Hemodialysis patients face an exceptional risk in the current COVID19 pandemic, both for infection/transmission as well as for mortality. All efforts to reduce potential risk factors are needed to protect this vulnerable group. We aimed to evaluate risk factors for SARS-CoV-2 infection and transmission during the first COVID19 wave, in order to tackle these factors in the second.

Method

We included all hemodialysis patients who were dialyzed at our central institution on March 19, 2020 (date of first COVID19 diagnosis). External low care and home hemodialysis patients were excluded. Our central hemodialysis center has 5 dialysis shifts in 6 units located next to each other, with a separate seventh dialysis unit dedicated for COVID19 isolation. COVID19 infections were diagnosed with nasopharyngeal swab PCR at the discretion of the treating nephrologist. On May 18 and 19, after the first wave, all hemodialysis patients were evaluated for presence of SARS-CoV-2 antibodies using ELISA to screen for previous asymptomatic infections. Chi square and logistic regression were used for statistical analyses.

Results

216 hemodialysis patients were included in this study, with a mean age of 72 years old (IQR 65-83). COVID19 was diagnosed in 17 patients during the first wave: in 15 symptomatic cases through nasopharyngeal swab PCR and in two additional asymptomatic cases through SARS-CoV-2 IgG positivity. Interestingly, we observed that 58.8% of COVID19 patients were transported by the same transport company, while this company transports only 20.4% of hemodialysis patients (p=0.005) (Figure A). As such, 22.7% of patients transported by this company became infected (OR 6.93, 95% CI 2.49-20.34, p=0.0002).

Conclusion

Institutional transport was the most significant risk factor for SARS-CoV-2 infection among hemodialysis patients at our center. After stringent prevention measures we were able to prevent transmission during transport in the second wave of the COVID19 pandemic.

Towards personalized fluid monitoring in haemodialysis patients: thoracic bioimpedance signal shows strong correlation with fluid changes, a cohort study

Background

Haemodialysis (HD) patients are burdened by frequent fluid shifts which amplify their comorbidities. Bioimpedance (bioZ) is a promising technique to monitor changes in fluid status. The aim of this study is to investigate if the thoracic bioZ signal can track fluid changes during a HD session.

Methods

Prevalent patients from a single centre HD unit were monitored during one to six consecutive HD sessions using a wearable multi-frequency thoracic bioZ device. Ultrafiltration volume (UFV) was determined based on the interdialytic weight gain and target dry weight set by clinicians. The correlation between the bioZ signal and UFV was analysed on population level. Additionally regression models were built and validated per dialysis session.

Results

66 patients were included, resulting in a total of 133 HD sessions. Spearman correlation between the thoracic bioZ and UFV showed a significant strong correlation of 0.755 (p < 0.01) on population level. Regression analysis per session revealed a strong relation between the bioZ value and the UFV (R² = 0.982). The fluid extraction prediction error of the leave-one-out cross validation was very small (56.2 ml [− 121.1–194.1 ml]) across all sessions at all frequencies.

Conclusions

This study demonstrated that thoracic bioZ is strongly correlated with fluid shifts during HD over a large range of UFVs. Furthermore, leave-one-out cross validation is a step towards personalized fluid monitoring during HD and could contribute to the creation of autonomous dialysis.

Optimized robotic setup for automated active thermography using advanced path planning and visibility study

In-line inspection of advanced components remains a challenging task in industry. The authors will describe an automated methodology that uses numerical simulations to automatically determine the best set of experimental parameters to inspect the structure on defects using active thermography. The inspection is performed using a robotic arm and advanced path-planning tools to determine the optimal positions of the measurement points and excitation points. During the path planning, the directional emissivity is considered for the complex surface, and a minimization of the amount of measurement points is performed. The numerical simulation optimization used a genetic algorithm and spline regression model to optimize the heat power, robot speed, camera frame rate, and excitation timing to fulfill the automatic inspection.

Measuring hindfoot alignment in weight bearing CT: A novel clinical relevant measurement method

BACKGROUND

A precise pre-operative measurement of hindfoot malalignment is paramount to plan and obtain an accurate surgical correction. Hindfoot alignment is currently determined on standard weightbearing radiographs. However this is hampered by the superposition of the skeletal structures. Recent technology developed weightbearing cone beam CT to overcome this problem. The objective is to introduce a clinically relevant and reproducible method to measure hindfoot alignment on weightbearing CT.

METHODS

Sixty malalignments of the hindfoot were divided in to two groups; group one containing a valgus alignment (n=30) and group two a varus alignment (n=30) of the hindfoot. Imaging techniques used were standard radiographs and a weightbearing CT (pedCAT^®). Following angles were measured by two different authors: standard long axial hindfoot angle both on standard radiographs and on CT, clinical hindfoot, novel hindfoot angle, talar shift (distance from a neutral alignment), tibial inclination angle, talar tilt and subtalar vertical angle on CT.

RESULTS

Hindfoot alignment angles showed to significantly differ from each other (P<0.001). The novel hindfoot alignment angle showed the highest correlation with the clinical measurement method. Correlation of this novel angle with the talar shift showed a Spearman's correlation coefficient=0.87. Interclass correlation coefficient of the novel hindfoot alignment angle=0.72 and was the highest among the hindfoot alignment angles.

CONCLUSION

Weightbearing CT is allows to objectively assess hindfoot alignment. The proposed novel hindfoot alignment angle showed to be both clinically relevant and reproducible as compared to previous methods. The lateral tibiocalcaneal shift, on which the angle is highly correlated to, can help the surgeon in determining how much translation is necessary to obtain a neutral alignment during a calcaneal osteotomy.

LEVEL OF EVIDENCE

Level III: retrospective cohort study.

Radiological and clinical outcome of arthroscopic labral repair with all-suture anchors

PURPOSE

The aim of this study was to assess radiological and clinical outcome after arthroscopic all--suture anchor labral repair.

METHOD

20 patients treated for anterior and superior labral instability (mean age 29, range 14-51 years) were assessed at a minimum follow-up time of 1 year (mean 19 months ; range, 12-28 months). Postoperative MRI scans were assessed by 3 independent radiologists. The radiological appearance of bone at the anchor-site was judged by the presence of cyst formation, tunnel widening (> 2 mm) or bone edema. Clinical outcome analysis included standard follow-up and the Disabilities of the Arm, Shoulder and Hand score (DASH), Constant Shoulder score and the Western Ontario Shoulder Instability Index (WOSI).

RESULT

All patients were available for follow-up. In total, 58 all-suture anchors were implanted. None of the patients displayed large cyst formation. Small cysts were found in two patients (2 anchors). Tunnel widening was apparent in 3 patients (3 anchors) with an average widening of 3.3 mm (range 3-4 mm). Bone edema at the anchor-site was seen in 6 patients (8 anchors). The remaining 9 patients (45 anchors) did not display reactive bone changes. Clinical outcomes showed a WOSI of 70.6, a DASH of 18.9 and a Constant score of 89.3, and no recurrence of instability.

CONCLUSIONS

Satisfying radiological and clinical outcome was observed after arthroscopic instability surgery using all-suture anchors. Imaging revealed good labral healing without important bony reactions or the formation of large cysts at early follow-up. Level of evidence : IV Case series.

Abstract P6-08-06: Neoadjuvant tamoxifen therapy synchronizes ERα binding and gene expression profiles

Background: The majority of breast cancer patients are diagnosed with ERα-positive breast cancer. Most ERα-positive patients are treated with adjuvant endocrine therapy — typically tamoxifen or aromatase inhibitors — to block cellular proliferation. Although these treatments are considered successful, resistance is common. Notably, cross-resistance between the two types of therapies is not always observed suggesting molecular heterogeneity and underlining the need for development of personalized treatments. The Anastrozole, Fulvestrant or Tamoxifen Exposure — Response in molecular profile study (AFTER study, NCT00738777) aims to investigate prospectively whether short-term treatment can induce molecular changes indicative of pre-operative therapy response. Study Design: ERα-positive breast cancer patients are included in this open-label multicenter study. Post-menopausal patients are randomized between tamoxifen, anastrozole and fulvestrant and pre-menopausal and male patients receive tamoxifen. Treatment occurs during the pre-operative window between diagnosis and surgery (4±2 weeks). Clinical characteristics collected are ERα/PR and HER2 status as well as lymph-node status. The primary endpoint is the decrease in tumor cell proliferation, as assessed by Ki67 gene expression and published cell proliferation gene expression signatures. All data are collected from both pre- and post-treatment samples. Additionally, we will compare the changes induced by treatment in gene expression, ERα/DNA binding interactions, DNA copy number, endoxifen and estradiol levels. Results: Among 67 patients currently enrolled, we examined the data from the subset of 28 tamoxifen treated patients. ERα and PR levels did not differ significantly between pre- and post-treatment. All tumors were HER2-negative. Proliferation examined by Ki67 (IHC and gene expression, MKI67) was significantly lower in post-treatment samples (P &lt; 0.01). A significant association was identified with the change in gene expression proliferation signature score and change in MKI67 (rho = 0.7, P &lt; 0.001). We identified two samples, which changed from MammaPrint (MP) low-risk to high-risk among 17 pairs with data. One sample's score was on the cutoff for high-risk definition. Interestingly, the second sample also had an increase in Ki67 gene expression and proliferation gene signature score in the post-treatment sample. Overall, ERα/DNA binding interaction regions overlapped significantly more among post-treatment samples as compared to pre-treatment samples (P &lt;0.001). There were 3 samples that increased in MKI67 gene expression after drug exposure. Among these, only the MP low- to high-risk sample had an increase in proliferation gene signature and decrease in ERα/DNA binding interactions. Conclusions: Pre-treatment samples were more variable for both proliferation gene expression signatures and ERα/DNA binding interactions indicating the underlying molecular heterogeneity of the group prior to therapy. This inter-tumor heterogeneity appears to have been lowered by exposure to tamoxifen. Interestingly, not all samples were uniform in their response to tamoxifen exposure as measured by Ki67 and MP scores suggesting samples taken after treatment exposure may be useful for predictive biomarker discovery.

Citation Format: Linn SC, Severson TM, Nevedomskaya E, Peeters J, van Rossum A, Kuilman T, Krijgsman O, Goossens I, Glas A, Koornstra R, Peeper D, Wesseling J, Simon I, Wessels L, Zwart W. Neoadjuvant tamoxifen therapy synchronizes ERα binding and gene expression profiles. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-08-06.

[Problems and needs of informal caregivers of persons with dementia: a comparison between the initial stage and subsequent stages of the illness process]

This paper investigates whether informal caregivers of persons who have had symptoms of dementia for less than a year, differ from informal caregivers of persons in subsequent stages of dementia. Differences will be investigated in (a) problems experienced in the provision of informal care, (b) the use of ambulatory types of professional support, and (c) the need for additional professional support. Results are based on a survey among 1494 Dutch informal caregivers. Almost all informal caregivers experience problems in caring for a person with dementia, irrespective of the stage of the illness process. Their main problems concern dealing with changes in the behaviour of the person with dementia and dreading the person's admission to a nursing home. Informal caregivers of persons who have had symptoms of dementia for a longer period of time (> 1 year) also experience limitations in their social network. Most persons with dementia receive some kind of professional support. Still, the majority of informal caregivers indicate a need for additional professional support, mainly concerning advice and information. Limiting the available support options for persons with initial symptoms of dementia and their informal caregivers is therefore undesirable. Considering the need for additional support in the initial stage of dementia as well as in subsequent stages, persons with dementia and their informal caregivers should be supported during the entire illness process.

A structure-activity relationship for the rate coefficient of H-migration in substituted alkoxy radicals

A framework is formulated for the development of a predictive structure-activity relationship for the temperature-dependent rate coefficients of H-migration in substituted alkoxy radicals. It is based on a multi-conformer transition state theory model, using quantum chemical characterizations of alkoxy radicals and their transition states for isomerisation. Using this framework, a SAR is then developed for the prediction of rate coefficients at 1 atm and T = 250-350 K, relative to a set of three reference reactions. The SAR covers 1,4-through 1,8-H-migration, as well as oxo- and hydroxy substitution in various positions relative to the radical oxygen and the migrating H.

A multiplex PCR to identify porcine mycoplasmas present in broth cultures

Mycoplasma hyopneumoniae, Mycoplasma hyorhinis and Mycoplasma flocculare can be present in the lungs of pigs at the same time. These three mycoplasma species all require similar growth conditions and can be recovered from clinical samples using the same media. We have developed a multiplex PCR as a helpful tool for rapid differentiation of these three species in the course of isolation. Based on the 16S ribosomal DNA sequences, three different forward primers and a single reverse primer were selected. Each forward primer was compared to available mycoplasma sequences, showing the primers to be specific. The three amplification products observed of 1129 bp (M. hyorhinis), 1000 bp (M. hyopneumoniae) and 754 bp (M. flocculare) were clearly distinguishable on a 1% agarose gel. In addition, no cross-reaction with Mycoplasma hyosynoviae, another porcine mycoplasma, was noted. This multiplex PCR using the proposed set of primers is the first reported assay that allows the simultaneous identification of the different Mycoplasma species isolated from the lungs of pigs.

Decomposition of substituted alkoxy radicals--part I: a generalized structure-activity relationship for reaction barrier heights

An update and expansion of our readily applicable structure-activity relationship (SAR) for predicting the barrier height E(b) to decomposition by beta C-C scission of (substituted) alkoxy radicals is presented. Such alkoxy radicals are key intermediates in the atmospheric oxidation of volatile organic compounds, and a correct description of their chemistry is vital to the understanding of atmospheric chemistry; nevertheless, experimental data on these reactions remain scarce. The SAR is based on quantum chemical characterizations of a large set of alkoxy radicals, and accommodates alkoxy radicals with alkyl- (-R), oxo- (=O), hydroxy- (-OH), hydroperoxy (-OOH), alkoxy (-OR), alkylperoxy- (-OOR), nitroso- (-NO), nitro- (-NO2), nitrosooxy- (-ONO), and nitroxy- (-ONO2) functionalities, as well as 3- to 6-membered rings and some unsaturated side chains. The SAR expresses the barrier height to decomposition, E(b) = 17.9 kcal mol(-1) + Sigma N(s) x F(s), as a linear function of the number N(s) of these substituents on the relevant carbons, and the substituent-specific activities F(s) derived from the quantum chemical calculations, allowing facile predictions based solely on the molecular structure. For low barriers, < or = 7 kcal mol(-1), a simple curvature correction is required. The SAR-predicted barrier height E(b) can be used to predict the high-pressure rate coefficient for alkoxy decomposition k(diss) at or around 298 K.

Physiology of Aspergillus niger in oxygen-limited continuous cultures: Influence of aeration, carbon source concentration and dilution rate

In industrial production of enzymes using the filamentous fungus Aspergillus niger supply of sufficient oxygen is often a limitation, resulting in the formation of by-products such as polyols. In order to identify the mechanisms behind formation of the different by-products we studied the effect of low oxygen availability, at different carbon source concentrations and at different specific growth rates, on the metabolism of A. niger, using continuous cultures. The results show that there is an increase in the production of tricarboxylic acid (TCA) cycle intermediates at low oxygen concentrations. Indeed, at these conditions, a decrease in the mitochondrial respiratory chain activity leads to an accumulation of NADH and to a decreased ATP production which uncouples catabolism and anabolism, influences the intracellular pH and leads to production and excretion of organic acids. Moreover, mannitol is being produced in order to ensure reoxidation of NADH, and this is the main cellular response to balance the ratio NADH/NAD at low oxygen availability. Mannitol production is also coupled to low specific growth rate, which suggests a control of carbon catabolite repression on the mannitol pathway. The roles of two other polyols, erythritol and glycerol, were also investigated. Both compounds are known to accumulate intracellularly, at high osmotic pressure, in order to restore the osmotic balance, but we show that the efficiency of this system is affected by a leakage of polyols through the membrane.

Low-volatility poly-oxygenates in the OH-initiated atmospheric oxidation of alpha-pinene: impact of non-traditional peroxyl radical chemistry

Following new insights on non-traditional peroxyl radical chemistry, we present an update to our earlier OH-initiated alpha-pinene degradation mechanism (Peeters et al., Phys. Chem. Chem. Phys., 2001, 3, 5489), incorporating ring closure reactions and a fast H-shift isomerization in certain key peroxyl and oxy radical intermediates. These changes, affecting only a single branch of the comprehensive mechanism and based on extensive quantum-chemical and theoretical kinetic calculations, show significant formation, approximately 20% overall, of poly-oxygenated (hydro)peroxides in atmospheric conditions. These low-volatility compounds are expected to have a significant impact on aerosol formation, and are believed to be the high-mass product compounds observed in available experimental work. The proposed changes also affect the predicted acetone yield, matching the experimental data closely.

HOx radical regeneration in the oxidation of isoprene

We propose, and quantify from first principles, two novel HO(x)-regenerating unimolecular reactions in isoprene oxidation, which are estimated to yield in pristine tropical forest conditions about 0.7 HO(2) and 0.03 OH radicals per isoprene oxidized; it is further argued that the photolabile coproduct of HO(2) can be a major source of OH, with a yield of the order of 1. The newly proposed chemistry could provide a rationalization for the unexpectedly high OH concentrations often observed in forested environments, such as over the Amazon forest in the recent Gabriel campaign.

Deletion of frizzled-related protein reduces voluntary running exercise performance in mice

OBJECTIVE

To study the effect of frizzled-related protein (Frzb) deletion in mice on voluntary running wheel exercise performance and osteoarthritis.

METHODS

At the age of 7 weeks, Frzb(-/-) and wild-type mice were grouped and a running wheel was introduced into the cage. At week 8, all mice were caged solitarily with a running wheel available. Mice were allowed free exercise for 6-12 months and distances run were recorded daily. Non-running mice were used as additional control group. X-rays of knees and hips were taken at different time points. At the end of the experiment, mice were sacrificed and joints were processed for histological evaluation. Cartilage damage, synovitis and osteophyte formation were scored. Muscle fiber composition of the soleus and extensor digitorum longus was studied by immunofluorescence.

RESULTS

At the age of 6 months, both female and male wild-type mice showed a significantly greater exercise performance than the Frzb(-/-) mice (P<0.05). At 1 year, the difference was still significant for male mice, but not for females. Running exercise did not significantly affect severity of osteoarthritis. No statistical differences in osteoarthritis severity were seen between Frzb(-/-) mice and wild-type mice. No differences were seen in muscle composition between Frzb(-/-) mice and wild-type mice.

CONCLUSION

Absence of Frzb in mice reduced voluntary exercise performance in running wheels. These experiments demonstrate that the effects of genes in mice can also be evaluated using functional outcomes such as running wheel exercise performance, similar to evolving practice in human clinical trials.

MR arthrography of the hip joint: a practical approach

This paper briefly reviews the technique of direct MR arthrography, MR anatomy and pathologic conditions of the acetabular labrum. Normal variants that may simulate pathology are also illustrated.

Imaging of femoroacetabular impingement: pictorial review

Femoroacetabular impingement (FAI) is a cause of progressive osteoarthritis of the hip in younger patients. Three types of FAI have been described: a cam-type, a pincer-type and a mixed type. Early recognition of the morphologic hip features of each type of impingement is important, because arthroscopic treatment is still successful in the initial stage to prevent or delay further hip degeneration. This article reviews the imaging features of the different types of FAI. Magnetic resonance arthrography (MRA) is the preferred modality to detect, localise and characterise the type of FAI and the resulting injuries of the acetabular hyaline cartilage and fibrocartilaginous labrum.

Supersaturating drug delivery systems: effect of hydrophilic cyclodextrins and other excipients on the formation and stabilization of supersaturated drug solutions

Supersaturating drug delivery systems (SDDS) utilize two important design elements in their preparation including converting the drug of interest into a high energy state or other rapidly dissolving form to facilitate the formation of supersaturated drug solutions and providing a means for stabilizing the formed supersaturated solution such that significant drug absorption is possible from the gastrointestinal tract. This has been referred to as a "spring" and "parachute" approach. The current effort is designed to assess materials which may affect properties in SDDS. To this end, a series of excipients was tested in a co-solvent/solvent quench method to assess their ability to attain and maintain supersaturation for a group of 14 drug development candidates. The approach focussed on hydrophilic cyclodextrins including hydroxypropyl-beta-cyclodextrin (HPbetaCD) and sulfobutyl-beta-cyclodextrin (SBEbetaCD). Various rheological polymers and surfactants were also included in the study. Consistent with previous investigations, the pharmaceutical polymers, as a class, had minimal effects on the extent of supersaturation but tended to be good stabilizers while the surfactants tended to provide for the greatest degree of supersaturation but the formed systems were poorly stable. This study found that hydrophilic cyclodextrins, especially SBEbetaCD, gave superior results in terms of attaining and maintaining supersaturation. A knowledge of the behavior and performance of excipients in this context can be useful in designing solid oral dosage forms for difficult-to-formulate drugs and drug candidates.

Kinetic parameters for gas-phase reactions: experimental and theoretical challenges

This article aims to illustrate the added value provided to experimental kinetics investigations by complementary theoretical kinetics studies, using as examples (i) reactions of two major hydrocarbon flame radicals, HCCO and C(2)H, and (ii) reactions of several oxygenated organic compounds with hydroxyl radicals of interest to atmospheric chemistry. The first part, on HCCO and C(2)H kinetics, does not attempt to give an extensive literature review, but rather addresses some major experimental techniques, mainly specific ones, that have allowed a great part of the available reactivity databases on these two species to be established. For several key reactions, it is shown how potential energy surfaces and statistical rate predictions based thereon have provided insight into the molecular mechanisms and have allowed estimates of product distributions as well as reliable extrapolations of experimental rate coefficients and branching ratios to higher temperatures. The second part addresses current issues in atmospheric chemistry relating mainly to hydroxyl radical reactions with oxygenated organics, and focuses on the experimental characterization of the often unusual temperature dependence of their rate coefficients and on the theoretical rationalization thereof, through the formation of hydrogen-bonded pre-reactive complexes and resulting tunnelling-enhanced H-abstraction. Finally, the development of general structure-activity relationships for OH reactions with organics, H-abstractions as well as OH-additions for unsaturated compounds, is briefly discussed.

Structure−Activity Relationship for the Addition of OH to (Poly)alkenes: Site-Specific and Total Rate Constants

A novel site-specific structure-activity relationship was developed for the site-specific addition of OH radicals to (poly)alkenes at 298 K. From a detailed structure-activity analysis of some 65 known OH + alkene and diene reactions, it appears that the total rate constant for this reaction class can be closely approximated by a sum of independent partial rate constants, ki, for addition to the specific (double-bonded) C atoms that depend only on the stability type of the ensuing radical (primary, secondary, etc.), that is, on the number of substituents on the neighboring C atom in the double bond. The (nine) independent partial rate constants, ki, were derived, and the predicted rate constants (kOH,pred = Sigmak(i)) were compared with experimental k(OH,exp) values. For noncyclic (poly)alkenes, including conjugated structures, the agreement is excellent (Delta < 10%). The SAR-predicted rate constants for cyclic (poly)alkenes are in general also within <15% of the experimental value. On the basis of this SAR, it is possible to predict the site-specific rate constants for (poly)alkene + OH reactions accurately, including larger biogenic compounds such as isoprene and terpenes. An important section is devoted to the rigorous experimental validation of the SAR predictions against direct measurements of the site-specific addition contributions within the alkene, for monoalkenes as well as conjugated alkenes. The measured site specificities are within 10-15% of the SAR predictions.

Theoretical and Experimental Study of the Product Branching in the Reaction of Acetic Acid with OH Radicals

The product distribution of the reaction of acetic acid, CH(3)COOH, with hydroxyl radicals, OH, was studied experimentally and theoretically. Mass-spectrometric measurements at 290 K and 2 Torr of He of the CO(2) yield versus the loss of acetic acid yielded a branching fraction of 64 +/- 14% for the abstraction of the acidic hydrogen as follows: CH(3)COOH + OH --> CH(3)COO + H(2)O --> CH(3) + CO(2) + H(2)O. A quantum chemical and theoretical kinetic analysis showed that the abstraction of the acidic hydrogen is enhanced relative to the abstraction of -CH(3) hydrogens because of the formation of a strong pre-reactive H-bonded complex, where the H-bonds are retained in the H-abstraction transition state. The potential energy surface of the reaction is explored in detail, and the reaction products of the individual channels are identified. The theoretical product branching is found to be critically dependent on the energetic and rovibrational differences between the H-abstraction transition states.

In vitro susceptibilities of Mycoplasma hyopneumoniae field isolates

The in vitro susceptibilities of 21 Mycoplasma hyopneumoniae field isolates were determined using a broth microdilution technique. One isolate showed acquired resistance to lincomycin, tilmicosin, and tylosin, while five isolates were resistant to flumequine and enrofloxacin. Acquired resistance against these antimicrobials in M. hyopneumoniae field isolates was not reported previously.

The use of polymer-based electrospun nanofibers containing amorphous drug dispersions for the delivery of poorly water-soluble pharmaceuticals

Electrostatic spinning was applied to the preparation of drug-laden nanofiber for potential use in oral and topical drug delivery. While this technique is in its infancy with regard to pharmaceutical applications, a number of recent publications suggest that it may be of high value in the formulation of poorly water-soluble drugs by combining nanotechnology and solid solution/dispersion methodologies. The purpose of this article is to describe some of these recently published applications. For immediate release oral application, a water-soluble cellulose polymer was selected (i.e., hydroxypropylmethylcellulose, HPMC) while for topical application, a nonbiodegradable, water-insoluble polymer was investigated (i.e., a segmented polyurethane, SPU). Solutions of the polymer and the drugs in appropriate solvents could be spun across various potentials (16-24 kV) generating nanofibers with diameters ranging from 300 to 2000 nm. Dissolution studies found that the non-woven fabrics derived from HPMC and containing itraconazole dissolved over a time course of minutes to hours depending on the formulation used as well as the drug/polymer ratios. Drug release from the SPU samples was dependent on the incorporated drug as well as nanostructure obtained.

A potential link between oral status and hearing impairment: preliminary observations

Some previous studies suggest an association between tooth loss and hearing loss. The aim of this study is to assess the relation between oral status and hearing acuity. Forty-eight patients (mean age: 64.7 years) were allocated to four groups: one was wearing complete dentures in both jaws, another had shortened dental arches, a third had full dental arches in both jaws and the last lacked any occlusal stops (i.e. no occlusal vertical dimension, because of the absence of teeth or occlusal pairs). Audiological testing was performed in a noise-free chamber. Air and bone conduction were checked at different frequencies and the air-bone gap was determined. After correction for age and gender, a difference in air and bone conduction because of the oral status was found for low and for high frequencies while no significant differences were (P < 0.05) found for the air-bone gap. The number of teeth, number of occluding tooth pairs and presence or lack of occlusal vertical dimension, was significantly related to the gradient of hearing loss (P < 0.05). The discrepancy in hearing loss between complete denture wearers and patients without any occlusal vertical dimension, strengthens the hypothesis that it is the lack of the latter that is associated with hearing loss. At what level hearing loss occurs, needs further investigation.

Evaluation of virulence of Mycoplasma hyopneumoniae field isolates

The course of enzootic pneumonia, caused by Mycoplasma hyopneumoniae, is strongly influenced by management and housing conditions. Other factors, including differences in virulence between M. hyopneumoniae strains, may also be involved. The aim of this study was to evaluate the virulence of six M. hyopneumoniae field isolates and link it to genetic differences as determined by randomly amplified polymorphic DNA (RAPD) analysis. Ninety, conventional M. hyopneumoniae-free piglets were inoculated intratracheally with the field isolates, a virulent reference strain or sterile culture medium. Animals were examined daily for the presence of disease signs and a respiratory disease score (RDS) was assessed per pig. Twenty-eight days post infection, pigs were euthanized, blood sampled and a lung lesion score was given. Lung samples were processed for histopathology, immunofluorescence testing for M. hyopneumoniae and isolation of M. hyopneumoniae. RAPD analysis was performed on all M. hyopneumoniae strains. Significant differences between isolates were found for the RDS, lung lesion score, histopathology, immunofluorescence and serology. Based on the results of the different parameters, isolates were divided into three "virulence" groups: low, moderately and highly virulent strains. Typically, a 5000 bp RAPD fragment was associated with the highly and moderately virulent strains whereas it was absent in low virulent strains. It was concluded that high variation in virulence exists between M. hyopneumoniae strains isolated from different swine herds. Further studies are required to determine whether the 5000 bp fragment obtained in the RAPD analysis can be used as a virulence marker.

Evaluation of different calorimetric methods to determine the glass transition temperature and molecular mobility below T(g) for amorphous drugs

The purpose of the present study was to compare different calorimetric methods used to determine the glass transition temperature (T(g)) and to evaluate the relaxation behaviour and hence the stability of amorphous drugs below their T(g). Data showed that the values of the activation energy for the transition of a glass to its super-cooled liquid state qualitatively correlate with the values of the mean molecular relaxation time constant of ketoconazole, itraconazole and miconazole, three structurally related drugs. Estimation of the molecular mobility by activation energy calculation indicated that loperamide was more stable than its two building blocks T263 and R731. It was further shown that the most commonly used approach to determine T(g) (T(g (1/2 c(p))) leads to erroneous values when enthalpy recovery is significant. In this case, an alternative method based on enthalpic considerations leads to results in accordance to basic thermodynamics. Estimation of molecular mobility based on activation energy calculations is therefore considered to be a valuable alternative for the method based on measurement of the extent of relaxation. When enthalpy relaxation is important, the use of T(g 1/2c(p)) leads to an overestimation of the T(g).