Microbiological epidemiology and antibiotic susceptibility of infected meshes after prosthetic abdominal wall repair

INTRODUCTION

Infectious complications of parietal mesh after prosthetic abdominal wall repair are rare. Their management is complex. Furthermore, the emergence of bacterial resistance, the presence of a foreign material, the need to continue an extended antibiotic therapy, and the choice of an appropriate treatment are crucial. The objective of this study is to access the microbiological epidemiology of infected parietal meshes in order to optimize the empirical antibiotic therapy.

METHODS

Between January 2016 and December 2021, a monocentric and retrospective study was performed in patients hospitalized for infected parietal meshes at Avicenne hospital, in Paris area. Clinical and microbiological data such as antibiotic susceptibility were collected.

RESULTS

Twenty-six patients with infected parietal meshes have been hospitalized during this period. Meshes were in preaponevrotic positions (n=10; 38%), retromuscular (n=6; 23%) and intraperitoneal (n=10; 38%). Among the 22 (84.6%) documented cases of infections, 17 (77.3%) were polymicrobial. A total of 54 bacteria were isolated, 48 of which had an antibiogram available. The most frequently isolated bacteria were: Enterobacterales (n=19), Enterococcus spp. (n=11) and Staphylococcus aureus (n=6), whereas anaerobes were poorly isolated (n=3). Concerning these isolated bacteria, amoxicillin-clavulanic acid, metronidazole-associated cefotaxime, piperacillin-tazobactam and meropenem were susceptible in 45.5%, 68.2%, 63.6%, 77.2%, of cases, respectively.

CONCLUSION

This work highlights that infections of abdominal parietal meshes may be polymicrobial and the association amoxicillin-clavulanic acid cannot be used as a probabilist antibiotic therapy because of the high resistance rate in isolated bacteria. The association piperacillin-tazobactam appears to be a more adapted empirical treatment to preserve carbapenems, a broad-spectrum antibiotic class.

Management of gastro-intestinal emergencies in patients with ileal conduit ureteral diversion

Radical cystectomy with urinary deviation is performed increasingly in France. Ileal conduit ureteral diversion (ICUD), described by Bricker and widely used after this type of radical resection, leads to substantial anatomic modifications that are potential danger zones during subsequent gastro-intestinal or urinary tract operations. Injury to the urinary diversion apparatus can lead to disastrous complications in these patients who are often elderly and frail. General surgeons are most often called upon to re-operate these patients, either for an ICUD-related gastro-intestinal complication, or for an unrelated abdominal emergency that arises later (bowel obstruction, infection, cancer). During such operations, certain anatomic structures are particularly exposed to injury that may be irreversible, particularly, the mesentery of the ileal conduit and the left ureter. Approaching the right lower quadrant, the dissection of the ileo-ileal anastomosis or of the left mesocolon are the procedures or maneuvers that pose the most risk. A number of simple but effective preventive measures are available and must be known, such as to operate the patient with an urologist or to insert ureteral stents before surgery. Preoperative contrast-enhanced computed tomography with late phase urinary imaging is essential to assess the anatomic modifications and anticipate the operative procedural steps. Finally, one should not hesitate to disinsert the stoma and proceed with retrograde dissection, thus facilitating the identification of the ileal conduit, the mesentery and the ureters.

A WC/WO star exploding within an expanding carbon-oxygen-neon nebula

The final fate of massive stars, and the nature of the compact remnants they leave behind (black holes and neutron stars), are open questions in astrophysics. Many massive stars are stripped of their outer hydrogen envelopes as they evolve. Such Wolf-Rayet stars¹ emit strong and rapidly expanding winds with speeds greater than 1,000 kilometres per second. A fraction of this population is also helium-depleted, with spectra dominated by highly ionized emission lines of carbon and oxygen (types WC/WO). Evidence indicates that the most commonly observed supernova explosions that lack hydrogen and helium (types Ib/Ic) cannot result from massive WC/WO stars^2,3, leading some to suggest that most such stars collapse directly into black holes without a visible supernova explosion⁴. Here we report observations of SN 2019hgp, beginning about a day after the explosion. Its short rise time and rapid decline place it among an emerging population of rapidly evolving transients^5-8. Spectroscopy reveals a rich set of emission lines indicating that the explosion occurred within a nebula composed of carbon, oxygen and neon. Narrow absorption features show that this material is expanding at high velocities (greater than 1,500 kilometres per second), requiring a compact progenitor. Our observations are consistent with an explosion of a massive WC/WO star, and suggest that massive Wolf-Rayet stars may be the progenitors of some rapidly evolving transients.

Management of abdominal compartment syndrome in acute pancreatitis

Abdominal compartment syndrome (ACS), defined by the presence of increased intra-abdominal pressure>20mmHg in association with failure of at least one organ system, is a common and feared complication that may occur in the early phase of severe acute pancreatitis (AP). This complication can lead to patient death in the very short term. The goal of this review is to provide the surgeon and intensivist with objective information to help them in their decision-making. In the early phase of severe AP, it is essential to monitor intra-vesical pressure (iVP) to allow early diagnosis of intra-abdominal hypertension or ACS. The treatment of ACS is both medical and surgical requiring close collaboration between the surgical and resuscitation teams. Medical treatment includes vascular volume repletion, prokinetic agents, effective curarization and percutaneous drainage of large-volume ascites. If uncontrolled respiratory or cardiac failure develops or if maximum medical treatment fails, most teams favor performing an emergency xipho-pubic decompression laparotomy with laparostomy. This procedure follows the principles of abbreviated laparotomy as described for abdominal trauma.

AB0412 URINARY SOLUBLE VCAM-1 IS A USEFUL BIOMARKER OF DISEASE ACTIVITY AND TREATMENT RESPONSE IN LUPUS NEPHRITIS

Background:

The traditional lupus nephritis (LN) biomarkers are not sensitive nor specific enough for detecting ongoing disease activity and early relapse of nephritis and they do not reflect kidney damage nor have prognostic value1. Urinary biomarkers are directly excreted by the kidney and are easily obtained. They can also differentiate the renal activity of the disease from other organic manifestations more accurately than the serum biomarkers2. Vascular cell adhesion molecule-1 (VCAM-1) is involved in the progression of glomerular and tubulointerstitial injury in LN and its soluble form can be easily assessed in urine (uVCAM-1)3. Several studies correlated the uVCAM-1 levels with urine protein-creatinine ratio (UPC), with general disease activity and with active LN3.

Objectives:

To assess uVCAM-1 as a biomarker of disease activity and treatment response in LN.

Methods:

This prospective study enrolled patients with class III, IV or V LN diagnosed within the last three years and divided them in two groups: with and without active nephritis at the inclusion. The patients with active nephritis were included before they started a new immunosuppressive treatment. Active LN was defined as proteinuria (UPC≥0.5) plus active urinary sediment (hematuria, leukocyturia or cellular hematic/granular casts). At each visit, a urine sample was collected for uVCAM-1 evaluation and the nephritis status was accessed.

Results:

Median uVCAM-1 level was elevated in patients with active compared to inactive LN (p<0.001). The ROC curve of uVCAM-1 demonstrated an AUC of 0.84 and a cutoff of 47.2 ng/mgCr yielded a good sensitivity (74.2%) and specificity (74.2%) for the diagnosis of active LN. A significant correlation was found between uVCAM-1 level and renal activity scores and traditional biomarkers of LN (table 1). The level of uVCAM-1 dropped in patients with active LN who went into remission (p<0.001), increased in patients who went into activity (p=0.002) and did not change in patients who remained inactive (p=0.797) (figure 1). The level of uVCAM-1 peaked during the flare of LN (p<0.05) (figure 2).

Table 1.

Correlations between urinary soluble VCAM-1 and other LN biomarkers/disease scores

LN biomarkers/disease scoresVCAM-1SLEDAI-2k0.597***Renal SLEDAI0.569***Renal SLAM-R0.470***Renal SLICC0.620***Anti-dsDNA0.342**C3-0.344**C4-0.382**UPC0.654***

Spearman’s correlation coefficients

*pvalue <0.05; **pvalue <0.01; ***pvalue <0.001

C, complement; LN, lupus nephritis; SLEDAI, Systemic Lupus Erythematosus Disease Activity Index; renal SLAM-R, The renal Systemic Lupus Activity Measure revised; renal SLICC, The Systemic Lupus International Collaborating Clinics renal activity/response exercise; UPC, urine protein-creatinine ratio.

Conclusion:

The uVCAM-1 is a reliable biomarker that reflects renal disease activity and is useful for monitoring individual patients with lupus nephritis over time.

References:

[1]Mok CC. Biomarkers for lupus nephritis: A critical appraisal. J Biomed Biotechnol. 2010;2010:638413.

[2]Reyes-Thomas J, Blanco I, Putterman C. Urinary Biomarkers in Lupus Nephritis. Clin Rev Allergy Immunol. 2010;40:138–50.

[3]Gasparin AA, Pamplona Bueno de Andrade N, Hax V, Tres GL, Veronese FV, Monticielo OA. Urinary biomarkers for lupus nephritis: the role of the vascular cell adhesion molecule-1. Lupus. 2019;28:265-272.

Acknowledgments:

We acknowledge the Research Incentive Fund (FIPE/HCPA) and the Research Support Fund of Brazilian Society of Rheumatology that supported this work.

Disclosure of Interests:

Andrese Aline Gasparin: None declared, Nicole Pamplona Bueno de Andrade: None declared, Vanessa Hax: None declared, Penelope Palominos Grant/research support from: This work was sponsored by the regional society of rheumatology (Sociedade de Reumatologia do Rio Grande do Sul)., Marina Siebert: None declared, Romulo Marx: None declared, Pedro Shaefer: None declared, Francisco Veríssimo Veronese: None declared, Odirlei Monticielo: None declared

Interaction between C-Tb and PPD given concomitantly in a split-body randomised controlled trial

SETTING

Seven tuberculosis (TB) clinics in South Africa.

OBJECTIVE

As both purified protein derivative (PPD) and a Mycobacterium tuberculosis-specific skin test (C-Tb) contain region of difference 1 (RD1) antigens, we conducted a study to evaluate whether there was any interaction between the two during concomitant and separate administration in patients with newly diagnosed culture-positive TB.

DESIGN

Adult patients with active TB (n = 456, 20% human immunodeficiency virus infected) were randomised to receive only C-Tb, only PPD, or concomitant injection of both C-Tb and PPD using the Mantoux technique. Indurations were read after 48-72 h. QuantiFERON^®-TB Gold In-Tube (QFT) was performed in tandem.

RESULTS

Of the 456 study participants, 154 simultaneously received both C-Tb and PPD, 153 only C-Tb and 149 only PPD. There was no effect of concomitant injection of PPD on the mean C-Tb induration (19 mm, 95%CI 17-22 vs. 18 mm, 95%CI 16-21; P = 0.91). In patients with active TB, C-Tb sensitivity (78%) was similar to PPD (81%) and QFT (84%; excluding 82/429 [19%] indeterminate results). All tests showed reduced sensitivity in participants with CD4 <100 cells/μl.

CONCLUSION

In patients with active TB, there was no interaction between C-Tb and PPD during concomitant injection of both agents. Sensitivities were similar for PPD and C-Tb.

Assessment of anti-Müllerian hormone levels in premenopausal patients with systemic lupus erythematosus

OBJECTIVE

The ovarian reserve of patients with systemic lupus erythematosus (SLE) may be affected by disease activity and medication use. Studies have found that patients with SLE have similar fertility rates as healthy women of the same age. The goal of the present study was to investigate the ovarian reserve of patients with SLE by measuring anti-Müllerian hormone (AMH) levels, and compare it to that of healthy controls.

METHOD

This was a case-control study performed on 80 premenopausal women, of whom 40 fulfilled the 1997 American College of Rheumatology (ACR) criteria for SLE and 40 healthy controls paired by oral contraceptive use. Serum concentrations of AMH in peripheral venous blood were measured using a human AMH ELISA kit (CUSABIO, Wuhan, China).

RESULTS

AMH serum levels did not differ between patients with SLE and controls (22.79 ± 17.32 ng/ml versus 21.41 ± 16.22 ng/ml, respectively, p = 0.7), even after adjusting for age (21.03 ± 2.074 ng/ml versus 23.97 ± 2.71 ng/ml; p = 0.5). AHM levels were not significantly correlated with disease duration (r = 0.2; p = 0.3), body mass index (r = 0.2; p = 0.2) and disease activity (SLEDAI (r = 0.1; p = 0.7)) and damage indices (SLICC (r = 0.1; p = 0.7)). No associations were found between AMH and ethnicity, current smoking, as well as current or prior use of cyclophosphamide and other immunosuppressants.

CONCLUSION

In this cross-sectional study, women with SLE demonstrated similar AMH levels as healthy controls, suggesting preserved ovarian reserve in this population.

5,5′-Diamino-BIPHEP ligands bearing small selector units for non-covalent binding of chiral analytes in solution

A dynamic axially chiral BIPHEP-ligand with 3,5-dichlorobenzoyl amide selector units for non-covalent binding of phenylalanine derivatives has been developed.

Glucocerebrosidase gene variants in parkinsonian patients with Machado Joseph/spinocerebellar ataxia 3

Machado-Joseph disease/spinocerebellar ataxia type 3 (MJD/SCA3) may rarely presents a parkinsonian phenotype. Considering that mutations in the glucocerebrosidase (GBA) gene have been associated with Parkinson disease, we investigated whether these would be more prevalent in MJD/SCA3 patients with parkinsonian manifestations than in those without them.

METHODS

MJD/SCA3 patients with parkinsonian features were identified and compared to relatives and to a MJD/SCA3 control group with no such features. The GBA gene was sequenced and, in a subset of patients and in normal volunteers, GBA enzyme activity was measured.

RESULTS

We have identified nine index MJD/SCA3 patients with parkinsonian manifestations. Overall, GBA sequence variations were found in 3/9 MJD/SCA3 index cases with parkinsonian manifestations (33%) and in 0/40 MJD/SCA3 controls without parkinsonism (p=0.03, Fisher exact test). The GBA sequence variations found were p.K(-27)R, p.E326K, and p.T369M. The latter two sequence variations were also found in two symptomatic relatives with no parkinsonian manifestations. A MJD/SCA3 relative belonging to the first positive pedigree and carrier of the p.K(-27)R mutation also presented parkinsonian manifestations. GBA activity in MJD/SCA3 patients was similar to those found in the normal control group.

CONCLUSION

Sequence variations at the GBA gene may play a role as a minor, modifying gene of MJD/SCA3 phenotype. This hypothetical role was not related to changes in GBA activity in peripheral leukocytes.

Local structure of uncapped and capped InGaN/GaN quantum dots

The local structure around the indium atoms in uncapped and capped In(x)Ga(1-x)N quantum dots has been studied by In K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The samples were grown by metal organic vapour phase epitaxy. The EXAFS was successfully applied to study the structural properties of buried quantum dots which are not optically active. The analysis revealed that capping the quantum dots with GaN does not affect the bond distances of the In-N and In-Ga, but makes the In-In distance shorter by 0.04 A.

In vivo contact areas of the knee in patients with patellar subluxation

OBJECTIVE

Ex vivo studies have suggested that cartilage contact areas and pressure are of high clinical relevance in the etiology of osteoarthritis in patients with patellar subluxation. The aims of this study were therefore to validate in vivo measurements of contact areas with 3D open magnetic resonance imaging (MRI), and to study knee joint contact areas in patients with patellar subluxation at different angles of knee flexion in comparison with healthy subjects.

METHODS

3D-MRI data sets of 12 healthy volunteers and eight patients with patellar subluxation were acquired using a standard clinical (1.5 T) and an open (0.2 T) MRI scanner. We compared femoro-patellar and femoro-tibial contact areas obtained with two different sequences from open MRI [dual-echo-steady-state (DESS) and fast-low-angle-shot (FLASH) sequences] with those derived from standard clinical 1.5 T MRI. We then analyzed differences in joint contact areas between healthy subjects and patients with patellar subluxation at 0 degree, 30 degrees, and 90 degrees of knee flexion using open MRI.

RESULTS

The correlation of the size of contact areas from open MRI with standard clinical MRI data ranged from r = 0.52 to 0.92. Open-MRI DESS displayed a smaller overestimation of joint contact areas (+21% in the femoro-patellar, +12% in the medial femoro-tibial, and +19% in the lateral femoro-tibial compartment) than FLASH (+40%, +37%, +30%, respectively). The femoro-patellar contact areas in patients were significantly reduced in comparison with healthy subjects (-47% at 0 degree, -56% at 30 degrees, and -42% at 90 degrees of flexion; all p < 0.01), whereas no significant difference was observed in femoro-tibial contact areas.

CONCLUSIONS

Open MRI allows one to quantify joint contact areas of the knee with reasonable accuracy, if an adequate pulse sequence is applied. The technique permits one to clearly identify differences between patients with patellar subluxation and healthy subjects at different flexion angles, demonstrating a significant reduction and lateralization of contact areas in patients. In the future, application of this in vivo technique is of particular interest for monitoring the efficacy of different types of surgical and conservative treatment options for patellar subluxation.

Use of novel interactive input devices for segmentation of articular cartilage from magnetic resonance images

OBJECTIVE

To study the effect of new interactive computer input devices on cartilage segmentation in terms of time, consistency between input devices, and precision in quantitative magnetic resonance imaging (qMRI).

DESIGN

We compared two new input devices, an interactive digitizing tablet and an interactive touch-sensitive screen, to a traditional mouse. Medial tibial and patellar cartilage of six healthy and six osteoarthritic knees were segmented using each input device. Cartilage volume, surface area and mean thickness were assessed using a validated algorithm and used to determine consistency and precision. Segmentation time was also measured.

RESULTS

Segmenting with an interactive touch-sensitive screen reduced segmentation time by 15% when compared to the traditional mouse but we found no significant difference in segmentation time between the interactive digitizing tablet and the traditional mouse. We found no difference in consistency or precision of cartilage volume, mean thickness or surface area between the three input devices tested.

CONCLUSIONS

We conclude that measurements of cartilage made using articular cartilage segmentation from MR images are independent of the input device chosen for user interaction.

Patella kinematics and patello-femoral contact areas in patients with genu varum and mild osteoarthritis

BACKGROUND

Patients with genu varum of the knee and moderate to severe osteoarthritis often suffer from additional symptoms of the patello-femoral joint. These patients have a poor prognosis following high tibial osteotomy. It is unclear whether varus knees with only mild femoro-tibial osteoarthritis are also associated with alterations of patella biomechanics, and affect the prognosis of intended high tibial osteotomy.

METHODS

Fifteen patients with genu varum and mild osteoarthritis and 15 healthy volunteers were assessed in an open MRI-scanner. 3D-GRE sequences of the knee were obtained in 0 degrees, 30 degrees and 90 degrees with and without activity of the extensor muscles. After segmentation of patella, femur, tibia and the adjacent cartilage, a patella-based local coordinate system was established. Femoral and tibial reference points allowed definition of the spatial position of the patella. Contact areas were defined by intersection of opposing cartilage volumes.

FINDINGS

No significant differences in patella kinematics and patello-femoral contact areas could be found (P > 0.05) between varus knees with mild osteoarthritis and healthy knees either at different flexion angles or under extending muscle activity.

INTERPRETATION

In knees with genu varum and mild medial osteoarthritis we could detect no alterations in patello-femoral kinematics. Since the alterations of patients with genu varum and mild osteoarthritis are restricted to the medial femoro-tibial joint high tibial osteotomy might be successful.

A new in vivo technique for determination of 3D kinematics and contact areas of the patello-femoral and tibio-femoral joint

Patello-femoral disorders are often caused by changes of patello-femoral and/or tibio-femoral kinematics. However, until now there has been no quantitative in vivo technique, that is able to obtain 3D kinematics and contact areas of all knee compartments simultaneously on a non-invasive basis. The aim of this study was therefore to develop and apply a technique which allows for determination of 3D kinematics and contact areas of the patello-femoral and tibio-femoral joint during different knee flexion angles and under neuromuscular activation patterns. One knee of each of the 10 healthy volunteers was examined in an open MR system under flexing isometric muscle activity at 30 degrees and 90 degrees. Three-dimensional kinematics and contact areas of the patello-femoral and tibio-femoral joints were analyzed by 3D image postprocessing. The reproducibility of the imaging technique yielded a coefficient of variation of 4.6% for patello-femoral, 4.7% for femoro-tibial displacement and 8.6% for contact areas. During knee flexion (30-90 degrees ), patella tilt (opened to medial) decreased (8.8+/-3.4 degrees vs. 4.6+/-3.1 degrees, p<0.05), while lateral patellar shift increased significantly (1.6+/-2.3mm vs. 3.4+/-3.0mm, p<0.05). Furthermore, a significant posterior translation and external rotation of the femur relative to the tibia was observed. Patello-femoral contact areas increased significantly in size (134+/-60mm(2) vs. 205+/-96 mm(2)) during knee flexion. This technique shows a high reproducibility and provides physiologic in vivo data of 3D kinematics and contact areas of the patello-femoral and the tibio-femoral joint during knee flexion. This allows for advanced in vivo diagnostics, and may help to improve therapy of patello-femoral disorders in the future.

Femoro-tibial and menisco-tibial translation patterns in patients with unilateral anterior cruciate ligament deficiency--a potential cause of secondary meniscal tears

OBJECTIVE

To analyze menisco-tibial and femoro-tibial translation patterns in healthy and ACL-deficient knees in different knee flexion angles under muscle activity.

METHODS

The ACL-deficient and contralateral healthy knees of 10 patients were examined with an open MRI system at 30 degrees and 90 degrees of knee flexion, under isometric contraction of the extensors or flexor muscle groups. Translations between the tibia, the femoral condyles and the menisci were analyzed by three-dimensional image postprocessing.

RESULTS

Posterior translation of the femur and menisci relative to the tibia occurred during knee flexion (30-90 degrees) in all knees. In ACL-deficient knees, posterior translation of the medial femoral condyle (+1.3 +/- 3.8 mm) was significantly larger than in healthy knee (-0.9 +/- 2.9 mm; p<0.05), while the translation pattern of the menisci was similar (med. meniscus 0.6 +/- 2.3 mm vs. 0.6 +/- 2.7 mm). Under isometric contraction of the extensors (relative to the flexor muscle group), an increased posterior position of the femur and menisci was observed at 30 degrees knee flexion, but not at 90 degrees. This applied to ACL-deficient and healthy knees.

CONCLUSIONS

This study shows a significant increase of translation of the medial femoral condyle in ACL-deficient knees, whereas menisco-tibial translation remains almost unchanged. This difference in translation patterns indicates that the posterior horn of the medial meniscus might encounter shear, potentially explaining the high rate of secondary medial meniscal tears in patients with ACL-deficiency.

Adult female voxel models of different stature and photon conversion coefficients for radiation protection

This paper describes the construction of three adult female voxel models, two whole-body and one from head to thighs, from computed tomographic data of 3 women of different stature. Voxel models (also called phantoms) are human models based on computed tomographic or magnetic resonance images obtained from high resolution continuous scans of a single individual. The gray-scale data or information content of the medical images are interpreted into tissues (i.e., organs), a process known as segmentation. The phantoms, consisting of millions of volume elements, called voxels, provide a three-dimensional representation of the human body and the spatial form of its constituent organs and structures. They were initially developed for radiation protection purposes to estimate the organ and effective doses and hence the risk to a person or population due to an irradiation. This paper also presents conversion coefficients for idealized geometries of external photon exposures of energies 10 keV-1 MeV for the three female models, calculated with a Monte Carlo code. Until now there were not any published data on conversion coefficients for explicit female voxel models. Such sets of conversion coefficients exist for voxel adult males or for MIRD-type male, female, and hermaphrodite models. Numerical differences of the calculated conversion coefficients for the voxel female models and MIRD-type models can amount up to 60% or more for external exposures and are due to the improved anatomical realism of the voxel models. The size of the model also has an effect on the conversion coefficients, particularly for deeper lying organs and energies below 200 keV. The three separate sets of conversion coefficients allow one to choose the most suitable model according to the size of the individual as well as to study the dosimetric variations due to the size of the model.

Morpho-functional visualization of dynamic MR-mammography

In view of an increasing use of breast MRI supplementing X-ray mammography, the purpose of this study was the development of a method for fast and efficient analysis of dynamic MR image series of the female breast. The image data sets were acquired with a saturation-recovery-turbo-FLASH sequence facilitating the detection of the kinetics of the contrast agent concentration in the whole breast with a high temporal and spatial resolution. In addition, a morphological 3D-FLASH data set was acquired. The dynamic image data sets were analyzed by tracer kinetic modeling in order to describe the physiological processes underlying the contrast enhancement in mathematical terms and thus enable the estimation of functional tissue specific parameters, reflecting the status of microcirculation. To display morphological and functional tissue information simultaneously, a multidimensional real-time visualization system (using 3D-texture mapping) was developed, which enables a practical and intuitive human-computer interface in virtual reality. The spatially differentiated representation of the computed functional tissue parameters superimposed on the anatomical information offers several possibilities: improved discernibility of contrast enhancement, inspection of the data volume in 3D-space and localization of lesions in space and thus fast and more natural recognition of topological coherencies. In a feasibility study, it could be demonstrated that multidimensional visualization of contrast enhancement in virtual reality is practical. Especially, detection and localization of multiple breast lesions may be an important application

Dynamic MR-mammography in virtual reality

In view of an increasing use of breast MRI supplementing X-ray mammography, the purpose of this study was the development of a method for fast and efficient analysis of dynamic MR image series of the female breast. The image data sets were acquired with a saturation-recovery-turbo-FLASH sequence facilitating the detection of the kinetics of the contrast agent concentration in the whole breast with. In addition, a morphological 3D-FLASH data set was acquired. The dynamic image data sets were analyzed by tracer kinetic modeling in order to describe the physiological processes underlying the contrast enhancement in mathematical terms and thus to enable the estimation of functional tissue specific parameters, reflecting the status of microcirculation. To display morphological and functional tissue information simultaneously, a multidimensional real-time visualization system (using 3D-texture mapping) was developed, which enables a practical and intuitive human-computer interface in virtual reality. The spatially differentiated representation of the computed functional tissue parameters superimposed on the anatomical information offers several possibilities: improved discernibility of contrast enhancement; inspection of the data volume in 3D-space using the features of rotation and transparency variation; localization of lesions in space and thus fast and more natural recognition of topological coherencies. In a feasibility study, it could be demonstrated that multidimensional visualization of contrast enhancement in virtual reality is a practicable idea. Especially, detection and localization of multiple breast lesions may be an important application.

Morphofunctional visualization of MR-mammography in virtual reality

In view of an increasing use of breast MRI supplementing X-ray mammography, the purpose of this study was the development of a method for fast and efficient analysis of dynamic MR image series of the female breast. The dynamic image data sets were analyzed by tracer kinetic modeling in order to describe the physiological processes underlying the contrast enhancement in mathematical terms and thus to enable the estimation of functional tissue specific parameters, reflecting the status of microcirculation. To display morphological and functional tissue information simultaneously, a multidimensional real-time visualization system (using 3D-texture mapping) was developed, which enables a practical and intuitive human-computer interface in virtual reality.

Intra-Operative electromyographic monitoring of extra-ocular motor nerves (Nn. III, VI) in skull base surgery

BACKGROUND

Extraocular motor nerves (Nn. III, IV, VI) are at risk of damage during skull base surgery. A new recording technique was employed in 18 patients suffering from various skull base tumours in order to extend intra-operative EMG monitoring to the extra-ocular muscles.

METHODS

Selective intra-operative EMG recordings were obtained from extra-ocular muscles by placement of single-shafted bipolar needle electrodes under the guidance of B-mode ultrasound to visualise the needle tip within the target muscle in the orbital cavity.

FINDINGS

Following bipolar electrical stimulation, the oculomotor nerve (N.III) was intra-operatively identified in 5 out of 7 cases, and the abducens nerve (N.VI) in 12 out of 18 cases. Postoperative (3-6 months) oculomotor nerve function remained unchanged in 5 and improved in 2 patients. No permanent deterioration was observed. Abducens nerve function deteriorated in two patients and improved in one case, but remained unchanged in 15 cases. No side effects occurred. There was neither any distinct relation of ocular motor nerve function to the kind and extent of SMA ("spontaneous muscle activity") patterns, nor could such relationship be detected with concern to neurophysiological parameters (latencies, amplitudes) of electrically evoked CMAP ("compound muscle action potentials").

INTERPRETATION

The EMG technique proposed proved to be mainly effective as a mapping tool for intra-operative localisation and identification of ocular motor nerves in skull base surgery. However, the predictive value of conventional neurophysiological parameters for clinical outcome, seems to be rather poor. Further studies on a larger number of patients are therefore required to develop new quantification techniques which enable an intra-operative prediction of ocular motor nerve deficits. Further efforts are also necessary to extend this technique to the trochlear nerve.

Quantitative image analysis of the cartilage in Virtual Reality

The objective of this work is to develop image processing methods for analysing the morphology of the joint cartilage with magnetic resonance imaging. Quantitative data on the morphological distribution of the joint cartilage are of great interest for both research as well as for diagnosis. The cartilage thickness provides information on the local cartilage occurance and may therefore be helpful in early and objective diagnosing degenerative cartilage changes, monitoring the pathogenesis of osteoarthritis, and controlling the success of chondroprotective treatment. In biomechanics, the thickness distribution serves to analyse the functional adaptation or the compression of the cartilage under loading and may be used for numerical simulation of load transmission in the joint.

Enzymic characterization of epidermis-derived 12-lipoxygenase isoenzymes

Substrate selectivity and other enzymic characteristics of two epidermis-derived lipoxygenases (LOXs), the epidermis-type (e) (12S)-LOX and (12R)-LOX, were compared with those of the platelet-type (p) (12S)-LOX. In contrast with p(12S)-LOX, e(12S)-LOX and (12R)-LOX exhibited no or very low reactivity towards the customary substrates linoleic acid and arachidonic acid but metabolized the corresponding fatty acid methyl esters, which, in contrast, were not accepted as substrates by p(12S)-LOX. Other esters of arachidonic acid and linoleic acid, including propan-2-yl and cholesterol esters, 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-linoleyl-sn-glycero-3-phosphoethanolamine, and ceramide 1 carrying an omega-linoleic acid ester, were not metabolized by these three LOX isoenzymes. Among various polyunsaturated fatty acids the isomeric eicosatrienoic acids were found to be oxygenated by e(12S)-LOX but not by (12R)-LOX. 4,7,10,13,16,19-Docosahexaenoic acid as a substrate was restricted to p(12S)-LOX. Variations in the pH and the Ca(2+) content of the incubation medium affected the catalytic potential only slightly. Whereas (12R)-LOX activity increased in the presence of Ca(2+) and with an acidic pH, Ca(2+) had no effect on p(12S)-LOX and e(12S)-LOX; an acidic pH decreased the catalytic activity of the latter two. However, the catalytic activity of the epidermis-type isoenzymes, but not of p(12S)-LOX, was found to be markedly increased in the presence of DMSO. Under these conditions, e(12S)-LOX and (12R)-LOX oxygenated 4,7,10,13,16,19-docosahexaenoic acid to 14-hydroxy-4,7,10,12,16,19-docosahexaenoic acid and 13-hydroxy-4,7,10,14,16,19-docosahexaenoic acid respectively. In addition, (9R)-hydroxyoctadeca-10,12-dienoic acid methyl ester was generated from linoleic acid methyl ester by (12R)-LOX. Independently of the substrate, the catalytic activity of e(12S)-LOX and (12R)-LOX was always at most 2% of that of p(12S)-LOX with arachidonic acid as substrate.

[Dynamic MR mammography. Multidimensional visualization of contrast medium enhancement in virtual reality]

BACKGROUND

The purpose of this study was the development of a method for fast and efficient analysis of dynamic MR images of the female breast. The image data sets were acquired with a saturation-recovery turbo-FLASH sequence which enables the detection of the kinetics of the contrast agent concentration in the whole breast with a high temporal and spatial resolution. In addition, a morphologic 3D-FLASH data set was acquired.

METHODS

The dynamic image datasets were analyzed by a pharmacokinetic model which enables the representation of the relevant functional tissue information by two parameters. In order to display simultaneously morphologic and functional tissue information, we developed a multidimensional visualization system, which enables a practical and intuitive human-computer interface in virtual reality.

DISCUSSIONS

The developed system allows the fast and efficient analysis of dynamic MR data sets. An important clinical application is the localization and definition of multiple lesions of the female breast.

New Cleavase Fragment Length Polymorphism method improves the mutation detection assay

Cleavase Fragment Length Polymorphism (CFLP) analysis is a convenient, accurate and highly sensitive method for the detection and localization of nucleic acid mutations. The assay is well suited for high-throughput screening and can be used to detect mutations in known and unknown nucleic acid samples. A recent improvement in the CFLP assay termed "temperature ramping" or "ramping" is reported here. This procedural improvement eliminates the need for time and temperature optimizations before the actual sample analysis. In this study, we compare the CFLP ramping procedure to the conventional CFLP optimization procedure and demonstrate equal, and in some cases improved, detection of point mutations. With ramping, CFLP reactions are identical for all DNA fragments analyzed, which allows for increased sample throughput, decreased assay time and lower overall cost.

Comparison of detection platforms and post-polymerase chain reaction DNA purification methods for use in conjunction with Cleavase fragment length polymorphism analysis

The removal of impurities and contaminants from PCR-amplified fragments is important for mutation detection methods which identify mutations based on shifts in electrophoretic mobility. This is particularly critical for assays and detection methods which use target DNA that is labeled prior to analysis and electrophoretic detection. We examined several procedures for purifying DNA amplified by the polymerase chain reaction (PCR) and their use in conjunction with a novel DNA scanning method, the Cleavase fragment length polymorphism (CFLP)* assay. In this study, a 480 bp DNA fragment, fluorescently labeled on the 5'-end of one strand, was amplified and subjected to various widely used purification procedures, including several commercially available clean-up kits. We demonstrate that visualization of the fluorescent label, as opposed to simple ethidium bromide staining, reveals the presence of considerable levels of labeled, truncated, amplification products. The various procedures were evaluated on the basis of their ability to remove these unwanted DNA fragments as well as on the degree to which they inhibited or promoted the CFLP reaction. Several procedures are recommended for use with CFLP analysis, including isopropanol precipitation, gel excision, and several commercially available spin columns. Concurrently, we evaluated (compared) a number of commonly used visualization platforms, including fluorescence imaging, chemiluminescence, and post-electrophoretic staining, for the ability to detect CFLP pattern changes. The advantages and disadvantages of different methods are discussed and amounts of DNA to be used for CFLP analysis on different detection platforms are recommended.

Comparison of detection platforms and post-polymerase chain reaction DNA purification methods for use in conjunction with Cleavase fragment length polymorphism analysis

The removal of impurities and contaminants from PCR-amplified fragments is important for mutation detection methods which identify mutations based on shifts in electrophoretic mobility. This is particularly critical for assays and detection methods which use target DNA that is labeled prior to analysis and electrophoretic detection. We examined several procedures for purifying DNA amplified by the polymerase chain reaction (PCR) and their use in conjunction with a novel DNA scanning method, the Cleavase fragment length polymorphism (CFLP)* assay. In this study, a 480 bp DNA fragment, fluorescently labeled on the 5'-end of one strand, was amplified and subjected to various widely used purification procedures, including several commercially available clean-up kits. We demonstrate that visualization of the fluorescent label, as opposed to simple ethidium bromide staining, reveals the presence of considerable levels of labeled, truncated, amplification products. The various procedures were evaluated on the basis of their ability to remove these unwanted DNA fragments as well as on the degree to which they inhibited or promoted the CFLP reaction. Several procedures are recommended for use with CFLP analysis, including isopropanol precipitation, gel excision, and several commercially available spin columns. Concurrently, we evaluated (compared) a number of commonly used visualization platforms, including fluorescence imaging, chemiluminescence, and post-electrophoretic staining, for the ability to detect CFLP pattern changes. The advantages and disadvantages of different methods are discussed and amounts of DNA to be used for CFLP analysis on different detection platforms are recommended.

Detection of p53 gene mutations: analysis by single-strand conformation polymorphism and Cleavase fragment length polymorphism

We have generated a collection of clones containing single point mutations within the exon 5-9 hot spot regions of the p53 gene by using polymerase chain reaction (PCR) to amplify select regions of the gene from characterized cell lines. These clones were then used to address the sensitivity of mutation detection using slab-gel single-strand conformation polymorphism (SSCP) and Cleavase fragment length polymorphism (CFLP) assay systems. Both methods exhibited high sensitivities for the detection of mutations in cloned p53 mutations in this study: 97% for CFLP and 94% for SSCP. In addition to resulting in higher sensitivity of mutation detection, CFLP has the capability to analyze longer fragments. In this study, CFLP identified five intronic mutations which were not investigated in the exon-specific SSCP assay. These results agree with those found elsewhere and demonstrate that CFLP scanning can have practical advantages when used for the identification of sequence alterations within the p53 gene.

Murine 12(R)-lipoxygenase: functional expression, genomic structure and chromosomal localization

A cDNA, recently cloned (by Krieg et al. (1998)) from mouse skin, was shown to encode a 12(R)-lipoxygenase. When expressed in HEK cells, the recombinant protein converted methyl arachidonate into the corresponding 12-HETE ester which was shown to be the R-enantiomer by chiral phase chromatography. Neither arachidonic acid nor linoleic acid were substrates for the recombinant protein. The structure of the 12(R)-lipoxygenase gene is unique among all animal lipoxygenases in that it is divided into 15 exons and 14 introns spanning approximately 12.5 kb. By interspecific backcross analysis, the 12(R)-lipoxygenase gene was localized to the central region of mouse chromosome 11.

Technical developments in intra-operative monitoring for the preservation of cranial motor nerves and hearing in skull base surgery

Although EMG recordings from mimic muscles have become the standard for intra-operative facial nerve monitoring, few data are available concerning other motor cranial nerves (MCN). Auditory brainstem responses (ABR) are a proven tool for intra-operative hearing preservation, but have their limitations, suggesting the application of supplementary methods. This paper describes new developments of MCN and cochlear nerve monitoring in skull base surgery. Up to 2 x 8 EMG channels were recorded after bipolar stimulation of MCN using concentric coaxial probes. A special software enabled event-dependent registrations of all signals exceeding a definable threshold level. Selective recordings from masticatory muscles (N.V) were obtained using rectangular Teflon-insulated needle electrodes. For oculomotor (Nn.III/ VI) nerve recordings bipolar needle electrodes were precisely placed by orbital ultrasound guidance. Lower cranial nerves were monitored inserting needle electrodes into the soft palate (N.IX), tongue (N.XII) and vocal muscles (N.X) during laryngoscopy using a special applicator. For ABR recordings, click stimuli (95 dB HL) were applied monaurally through insert earphones. Electrocochleography was simultaneously recorded as a near-field potential without averaging after promontory (transtympanic) electrode placement using otomicroscopy. Regarding the ABR biosignal, a characteristic response pattern was detected following bipolar electrical stimulation of the auditory nerve possibly useful for its intra-operative identification.

Specific induction of secondary product formation in transgenic plant cell cultures using an inducible promoter

This paper describes the artificial induction of secondary metabolite production in transgenic plant cell cultures using a recombinant, inducible plant promoter. The bacterial gene ubiC from Escherichia coli encodes the enzyme chorismate pyruvate lyase (CPL) which catalyses the conversion of chorismate to 4-hydroxybenzoate (4HB). This gene was fused to the tetracycline-inducible plant promoter Triple-Op. After transformation into Nicotiana tabacum W38 TET, transgenic cell cultures were established. Addition of chlorotetracycline to the medium led to specific induction of CPL activity. The optimal chlorotetracycline concentration was approximately 2 mg/l medium. Three to 5 h after induction, the ubiC mRNA concentration reached a maximum, while highest specific CPL activity was detected after 8 days. The artificial secondary metabolite 4HB was converted to glucosides, and their accumulation reached maximum levels after 5 weeks of subculture. The induction was reversible.

An evaluation of salmeterol in the treatment of chronic obstructive pulmonary disease (COPD)

The objectives of this study were to compare the efficacy and safety of salmeterol xinafoate (50 and 100 microg b.i.d.) with that of placebo, when added to existing therapy, in the treatment of patients with chronic obstructive pulmonary disease (COPD). Six hundred and seventy four patients were randomized to receive either salmeterol 50 microg b.i.d., salmeterol 100 microg b.i.d., or placebo treatment for a period of 16 weeks. The results showed a significant improvement in daily symptom scores noted for patients taking either 50 microg (p=0.043) or 100 microg b.i.d. salmeterol (p=0.01) compared with placebo, with a corresponding decrease in additional daytime salbutamol requirements for both salmeterol groups. The same pattern was reflected for night-time symptoms and additional salbutamol use. During treatment, forced expiratory volume in one second (FEV1) measurements improved significantly in each salmeterol group, with up to a 7% improvement observed at the end of the study. Although no difference was observed between treatment groups for the distance walked in 6 min, patients treated with salmeterol 50 microg b.i.d. were significantly less breathless than those treated with placebo after their 6 min walk, after 8 weeks (p=0.024) and 16 weeks (p=0.004) of therapy. Adverse events were similar in all three groups except for tremor, which was significantly higher in the 100 microg b.i.d. salmeterol group (p=0.005) compared both with 50 microg b.i.d. salmeterol and placebo. Salmeterol offered further positive improvement to the effect of therapy in patients with chronic obstructive pulmonary disease when added to their existing regimens. This clinical improvement was similar both with 50 and 100 microg b.i.d. dosage, although the group receiving 50 microg b.i.d. tolerated the drug better than those receiving 100 microg b.i.d. salmeterol.

An evaluation of salmeterol in the treatment of chronic obstructive pulmonary disease (COPD)

The objectives of this study were to compare the efficacy and safety of salmeterol xinafoate (50 and 100 microg b.i.d.) with that of placebo, when added to existing therapy, in the treatment of patients with chronic obstructive pulmonary disease (COPD). Six hundred and seventy four patients were randomized to receive either salmeterol 50 microg b.i.d., salmeterol 100 microg b.i.d., or placebo treatment for a period of 16 weeks. The results showed a significant improvement in daily symptom scores noted for patients taking either 50 microg (p=0.043) or 100 microg b.i.d. salmeterol (p=0.01) compared with placebo, with a corresponding decrease in additional daytime salbutamol requirements for both salmeterol groups. The same pattern was reflected for night-time symptoms and additional salbutamol use. During treatment, forced expiratory volume in one second (FEV1) measurements improved significantly in each salmeterol group, with up to a 7% improvement observed at the end of the study. Although no difference was observed between treatment groups for the distance walked in 6 min, patients treated with salmeterol 50 microg b.i.d. were significantly less breathless than those treated with placebo after their 6 min walk, after 8 weeks (p=0.024) and 16 weeks (p=0.004) of therapy. Adverse events were similar in all three groups except for tremor, which was significantly higher in the 100 microg b.i.d. salmeterol group (p=0.005) compared both with 50 microg b.i.d. salmeterol and placebo. Salmeterol offered further positive improvement to the effect of therapy in patients with chronic obstructive pulmonary disease when added to their existing regimens. This clinical improvement was similar both with 50 and 100 microg b.i.d. dosage, although the group receiving 50 microg b.i.d. tolerated the drug better than those receiving 100 microg b.i.d. salmeterol.

Identification of novel graded polarity actin filament bundles in locomoting heart fibroblasts: implications for the generation of motile force

We have determined the structural organization and dynamic behavior of actin filaments in entire primary locomoting heart fibroblasts by S1 decoration, serial section EM, and photoactivation of fluorescence. As expected, actin filaments in the lamellipodium of these cells have uniform polarity with barbed ends facing forward. In the lamella, cell body, and tail there are two observable types of actin filament organization. A less abundant type is located on the inner surface of the plasma membrane and is composed of short, overlapping actin bundles (0.25-2.5 microm) that repeatedly alternate in polarity from uniform barbed ends forward to uniform pointed ends forward. This type of organization is similar to the organization we show for actin filament bundles (stress fibers) in nonlocomoting cells (PtK2 cells) and to the known organization of muscle sarcomeres. The more abundant type of actin filament organization in locomoting heart fibroblasts is mostly ventrally located and is composed of long, overlapping bundles (average 13 microm, but can reach up to about 30 microm) which span the length of the cell. This more abundant type has a novel graded polarity organization. In each actin bundle, polarity gradually changes along the length of the bundle. Actual actin filament polarity at any given point in the bundle is determined by position in the cell; the closer to the front of the cell the more barbed ends of actin filaments face forward. By photoactivation marking in locomoting heart fibroblasts, as expected in the lamellipodium, actin filaments flow rearward with respect to substrate. In the lamella, all marked and observed actin filaments remain stationary with respect to substrate as the fibroblast locomotes. In the cell body of locomoting fibroblasts there are two dynamic populations of actin filaments: one remains stationary and the other moves forward with respect to substrate at the rate of the cell body. This is the first time that the structural organization and dynamics of actin filaments have been determined in an entire locomoting cell. The organization, dynamics, and relative abundance of graded polarity actin filament bundles have important implications for the generation of motile force during primary heart fibroblast locomotion.