Fourier Transform Infrared Imaging of focal lesions in human osteoarthritic cartilage

Fourier Transform Infrared Imaging (FTIRI) is a new method for quantitatively assessing the spatial-chemical composition of complex materials. This technique has been applied to examine the feasibility of measuring changes in the composition and distribution of collagen and proteoglycan macromolecules in human osteoarthritic cartilage. Human cartilage was acquired post-operatively from total joint replacement patients. Samples were taken at the site of a focal lesion, adjacent to the lesion, and from relatively healthy cartilage away from the lesion. Sections were prepared for FTIRI and histochemical grading. FTIRI spectral images were acquired for the superficial, intermediate, and deep layers for each sample. Euclidean distance mapping and quantitative partial least squares analysis (PLS) were performed using reference spectra for type-II collagen and chondroitin 6-sulphate (CS6). FTIRI results were correlated to the histology-based Mankin scoring system. PLS analysis found relatively low relative concentrations of collagen (38 +/- 10%) and proteoglycan (22 +/- 9%) in osteoarthritic cartilage. Focal lesions were generally found to contain less CS6 compared to cartilage tissue adjacent to the lesion. Loss of proteoglycan content was well correlated to histological Mankin scores (r=0.69, p<0.0008). The evaluation of biological tissues with FTIRI can provide unique quantitative information on how disease can affect biochemical distribution and composition. This study has demonstrated that FTIRI is useful in quantitatively assessing pathology-related changes in the composition and distribution of primary macromolecular components of human osteoarthritic cartilage.

Fabry disease defined: baseline clinical manifestations of 366 patients in the Fabry Outcome Survey

BACKGROUND

Fabry disease is a rare X-linked disorder caused by deficient activity of the lysosomal enzyme alpha-galactosidase A. Progressive accumulation of the substrate globotriaosylceramide in cells throughout the body leads to major organ failure and premature death. In response to the recent introduction of enzyme replacement therapy, the Fabry Outcome Survey (FOS) was established to pool data from European clinics on the natural history of this little-known disease and to monitor the long-term efficacy and safety of treatment. This paper presents the first analysis of the FOS database and provides essential baseline data against which the effects of enzyme replacement can be measured.

DESIGN

Baseline data from a cohort of 366 patients from 11 European countries were analysed in terms of demography and clinical manifestations of Fabry disease.

RESULTS

Misdiagnosis of Fabry disease is common, and the mean delay from onset of symptoms to correct diagnosis was 13.7 and 16.3 years in males and females, respectively. Although previously thought to have serious manifestations only in hemizygous men, the FOS database has confirmed that females heterozygous for Fabry disease are similarly affected. Furthermore, signs and symptoms of Fabry disease may be present from early childhood.

CONCLUSIONS

With the advent of enzyme replacement therapy, it is important that general practitioners and physicians in a range of specialties recognize the signs and symptoms of Fabry disease so that effective treatment can be given. Baseline data from FOS demonstrate that enzyme replacement therapy should not be restricted to hemizygous men, but should be considered for both heterozygous females and children.

The Mainz Severity Score Index: a new instrument for quantifying the Anderson-Fabry disease phenotype, and the response of patients to enzyme replacement therapy

Anderson-Fabry disease (AFD) is an X-linked disorder caused by deficient activity of the lysosomal enzyme alpha-galactosidase A. The availability of enzyme replacement therapy (ERT) for this debilitating condition has led to the need for a convenient and sensitive instrument to monitor clinical effects in an individual patient. This study aimed to develop a scoring system--the Mainz Severity Score Index (MSSI)--to measure the severity of AFD and to monitor the clinical course of the disease in response to ERT. Thirty-nine patients (24 males and 15 females) with AFD were assessed using the MSSI immediately before and 1 year after commencing agalsidase alfa ERT. Control data were obtained from 23 patients in whom AFD was excluded. The MSSI of patients with AFD was significantly higher than that of patients with other severe debilitating diseases. The MSSI indicated that, although more men than women had symptoms classified as severe, overall, the median total severity scores were not significantly different between male and female patients. One year of ERT with agalsidase alfa led, in all patients, to a significant (p < 0.001) reduction in MSSI score (by a median of nine points). This study has shown that the MSSI score may be a useful, specific measure for objectively assessing the severity of AFD and for monitoring ERT-related treatment effects.

Magnetic resonance evaluation of the interrelationship between articular cartilage and trabecular bone of the osteoarthritic knee

OBJECTIVE

To use high-resolution magnetic resonance imaging (MRI) to determine the relationship between articular cartilage degeneration and trabecular bone changes of the femur, condyles and tibia in human knees with osteoarthritis (OA).

METHODS

Subjects were divided into three groups: without OA (OA0), mild OA (OA1) and severe OA (OA2). Sagittal images of the knee (0.234 x 0.234mm2, 2-mm slice thickness) were obtained at 1.5T and used for calculating the volume and thickness of the femoral and tibial cartilage. Axial images (0.195 x 0.195mm2, 1-mm slice thickness) were used for calculating the trabecular bone structure parameters: apparent bone volume fraction, trabecular number, trabecular separation and trabecular thickness.

RESULTS

Cartilage volume and thickness were less in patients with OA compared to normal controls (P<0.1). Articular cartilage thinning is associated with bone structure loss in the opposite femoral condyle (P<0.05). In varus OA, there were extensive correlations between medial tibia and medial femoral cartilage degeneration, and loss of bone structure in the lateral tibia and lateral condyle. Additional correlations existed between the compartmental differences (lateral minus medial) of cartilage thickness and bone structure.

CONCLUSION

Degradation of articular cartilage within a compartment correlates with a loss of bone structure in the opposite compartment. The correlation between the (L-M) differences corroborates this relationship. Malalignment of the knee due to cartilage degeneration is associated with bone formation in the diseased condyle and bone resorption in the opposite compartment.

Intestinal perforations in a premature infant caused by Bacillus cereus

Although Bacillus cereus is a ubiquitous bacterium, the incidence of neonatal infections is very low with only a few cases of B. cereus infections in neonates reported in the literature. We report the case of a premature infant with multiple intestinal perforations and an abdominal B. cereus infection. The initial course was characterized by severe cardiovascular shock, anemia, thrombocytopenia and disseminated intravascular coagulation, leading to periventricular leukomalacia, alopecia capitis and toxic epidermal necrolysis. The possible role of B. cereus-associated enterotoxins for the clinical manifestations are discussed. Our case confirms previous reports of severe clinical symptoms in B. cereus infection in premature neonates. We speculate that the systemic complications of B. cereus infection are at least partly related to the effect of B. cereus-associated enterotoxins.

A micro-computed tomography study of the trabecular bone structure in the femoral head

The goal of this study was to characterize the trabecular microarchitecture of the femoral head using micro-computed tomography (ICT). Femoral head specimens were obtained from subjects following total hip replacement. Cylindrical cores from the specimens were scanned to obtain 3-D images with an isotropic resolution of 26 Im. Bone structural parameters were evaluated on a per millimeter basis: relative bone volume (BV/TV), trabecular number (Tb.N), thickness (Tb.Th) and separation (Tb.Sp), structure model index (SMI), and connectivity (Conn.D). The ICT data show that the first two millimeters, starting at the joint surface, are characterized by more plate-like trabeculae, and are significantly denser than the underlying trabecular bone. Regional differences in the trabecular architecture reveal that the superior pole has significantly higher BV/TV, Tb.N and Tb.Th values, with lower Tb.Sp compared to the inferior and side poles. Because subchondral bone is essential in the load attenuation of joints, the difference in bone structure between the subchondral and trabecular bone might arise from the different functions each have within joint-forming bones. The denser trabecular structure of the superior pole as compared to the inferior pole can be interpreted as a functional adaptation to higher loading in this area.

Functional MRI of the kidney

Functional MR imaging of the kidney has a great potential of development because the functional parameters, which can be approached noninvasively, are multiple: glomerular filtration, tubular concentration and transit, blood volume and perfusion, diffusion, and oxygenation. Until now, its limitations in clinical applications are due to the difficulties in obtaining reproducible and reliable information in this mobile organ and, sometimes, in understanding the physiologic substrate of the signal changes observed. These approaches require either endogeneous contrast agents, such as water protons (for perfusion and diffusion) or deoxyhemogobin (for oxgenation), or exogeneous contrast agents such as gadolinium chelates (for filtration and perfusion) or iron oxide particles (for perfusion). Clinical validation of these methods and evaluation of their clinical impact are now worthwhile before diffusing them in clinical practice.

Use of gabapentin to reduce chronic neuropathic pain in Fabry disease

The effect of the anticonvulsant gabapentin on neuropathic pain was studied in six male patients with Fabry disease, aged 15-45 years. After 4 weeks of treatment, pain, as measured using the Brief Pain Inventory, was decreased compared with baseline. Treatment was generally well tolerated. This study indicates that gabapentin should be considered as a treatment option for the neuropathic pain of Fabry disease.

Percutaneous endovascular catheter aspiration thrombectomy of severe superior vena cava syndrome

We report a combined percutaneous endovascular approach, including thrombus aspiration and catheter directed local thrombolysis, followed by systemic thrombolytic therapy to treat severe superior vena cava syndrome in a 2 and 1/2 week old infant. This procedure was performed on the fifth postoperative day after major surgery. No treatment complications were observed. The only predisposing condition for thrombosis was a central venous line. No other acquired or genetic risk factors for thrombosis could be found.

Virtual reality computer animation of the effect of component position and design on stability after total hip arthroplasty

Virtual reality technology was utilized to assess the effect of component orientation and component design on the range of motion prior to impingement following total hip arthroplasty. Components were digitized, oriented in the pelvis, and computer animations were performed to assess the likelihood of dislocation with different combinations of component orientation.

Differences between neonates and adults in tissue-type-plasminogen activator (t-PA)-catalyzed plasminogen activation with various effectors and in carbohydrate sequences of fibrinogen chains

Our study investigates the effect of fetal and adult soluble fibrin (SF), fetal and adult fibrinogen Aalpha- and gamma-chains, as well as adult CNBr-fibrinogen fragments on tissue-type plasminogen activator (t-PA)-catalyzed plasminogen activation of both fetal and adult Glu-plasminogen types 1 and 2. In addition, we determined carbohydrate sequences of fetal and adult Bbeta- and gamma-chains by mass spectrometric analysis. In the absence of an effector, no substantial differences in the rate of plasmin formation could be seen between the fetal and adult plasminogen types. In the presence of an effector, both fetal Glu-plasminogen types revealed lower values for k(cat app) than the respective adult types. No differences could be seen in the values for K(m app). The resulting differences in catalytic efficiencies between the fetal and adult plasminogen types were much less than previously reported. No differences could be seen between fetal and adult effectors in stimulating t-PA-catalyzed plasminogen activation. Detailed analyses of the activation kinetics revealed a longer initial phase of slow plasmin formation of both fetal Glu-plasminogen types compared to their respective adult types, indicating a slower plasmin-induced modification of CNBr-fibrinogen fragments or SF by fetal plasmin. Mass spectrometric analysis of the N-glycans present on adult and fetal Bbeta- and gamma-fibrinogen chains showed the presence of a major monosialylated biantennary structure with lesser amounts of the disialylated form. In contrast to previous data, we conclude that catalytic efficiency of t-PA-catalyzed plasminogen activation in neonates is only slightly lower than in adults.

Comparison of three joint simulator wear debris isolation techniques: acid digestion, base digestion, and enzyme cleavage

Quantification of ultrahigh molecular weight polyethylene (UHMWPE) wear debris remains a challenging task in orthopedic device analysis. Currently, the weight loss method is the only accepted practice for quantifying the amount of wear generated from a PE component. This technique utilizes loaded soak controls and weight differences to account for polymeric material lost through wear mechanisms. This method enables the determination of the amount of wear in the orthopedic device, but it provides no information about debris particulate size distribution. In order to shed light on wear mechanisms, information about the wear debris and its size distribution is necessary. To date, particulate isolation has been performed using the base digestion technique. The method uses a strong base, ultracentrifugation, and filtration to digest serum constituents and to isolate PE debris from sera. It should be noted that particulate isolation methods provide valuable information about particulate size distribution and may elucidate the mechanisms of wear associated with polymeric orthopedic implants; however, these techniques do not yet provide a direct measure of the amount of wear. The aim of this study is to present alternative approaches to wear particle isolation for analysis of polymer wear in total joint replacements without recourse to ultracentrifugation. Three polymer wear debris isolation techniques (the base method, an acid treatment, and an enzymatic digestion technique) are compared for effectiveness in simulator studies. A requirement of each technique is that the wear particulate must be completely devoid of serum proteins in order to effectively image and count these particles. In all methods the isolation is performed through filtration and chemical treatment. Subsequently, the isolated polymer particles are imaged using scanning electron microscopy and quantified with digital image analysis. The results from this study clearly show that isolation can be performed without the use of ultracentrifugation and that these methods provide a viable option for wear debris analysis.

Diffusion tensor MRI of the human kidney

This study characterizes the diffusion anisotropy of the human kidney using a diffusion-weighted, single-shot echo planar imaging (EPI) sequence in order to access the full apparent diffusion tensor (ADT) within one breathhold. The fractional anisotropy (FA) of the cortex and the medulla were found to be 0.22 +/- 0.12 and 0.39 +/- 0.11, respectively (N = 10), which emphasizes the need for rotationally invariant diffusion measurements for clinical applications. Additional limitations for clinical diffusion imaging on the kidney are the strong susceptibility variations within the abdomen that restrict the use of imaging techniques employing long echo trains, and the severe motion sensitivity that limits the available imaging time to one breath-hold. To overcome these problems an isotropic, diffusion-weighted, segmented EPI protocol that facilitates the acquisition of high-resolution diffusion-weighted images within a single breath-hold was implemented. Using this method, the apparent diffusion coefficient (ADC) of the cortex and medulla were found to be 2.89 +/- 0.28. 10(-9) m2/s and 2.18 +/- 0.36. 10(-9) m2/s (N = 10).

First Croatian auditory brainstem implantation

A deaf female patient was diagnosed with bilateral acoustic neurinomas. Diagnosis incorporated the standard audiological battery for sensorineural hearing loss, computed tomography and magnetic resonance imaging. The left side had been operated on four years previously in another clinic using the suboccipital approach. The auditory brainstem implant surgery was performed on the 'second side' using the same approach. It was an uneventful operation with good anatomy and no serious post-operative complications. Post-operatively, the patient performed exceptionally well, with up to 50 per cent of words recognized in the opened set and 85 per cent in the closed set, both without lip-reading.

Fracture and fatigue properties of acrylic bone cement: the effects of mixing method, sterilization treatment, and molecular weight

The purpose of this study was to characterize the relative and combined effects of sterilization, molecular weight, and mixing method on the fracture and fatigue performance of acrylic bone cement. Palacos R brand bone cement powder was sterilized using ethylene oxide gas (EtO) or gamma irradiation. Nonsterile material was used as a control. Molecular weights of the bone-cement powders and cured cements were measured using gel permeation chromatography. Hand and vacuum mixing were employed to mold single edge-notched bend specimens for fracture toughness testing. Molded dog-bone specimens were used for fatigue tests. Electron microscopy was used to study fracture mechanisms. Analysis of variance and Student t-tests were used to compare fracture and fatigue performance between sterilization and mixing groups. Our results indicate that vacuum mixing improved significantly the fracture and fatigue resistance (P<.05, P<.07) over hand mixing in radiation-sterilized and EtO-sterilized groups. In vacuum-mixed cement, the degradation in molecular weight resulting from gamma irradiation decreased fracture resistance significantly when compared with EtO sterilization and control (P<.05). A corresponding decrease in fatigue resistance was observed in the cement that was degraded severely by a radiation dose of 10 MRad (P<.05). In contrast, EtO sterilization did not result in a significantly different fracture resistance when compared with unsterilized controls for vacuum-mixed cement (P>.1). For hand-mixed cement, fracture and fatigue resistance appeared to be independent of sterilization method. This independence is believed to be the result of higher porosity that compromised the mechanical properties and obscures any effect of sterilization. Our results indicate that a combination of nonionizing sterilization and vacuum mixing resulted in the best mechanical performance and is most likely to contribute to enhanced longevity in vivo.

Diffusion tensor MRI of the spinal cord

Apparent diffusion tensor (ADT) measurements on the spinal cord using a pulsed-field-gradient (PFG) multi-shot echo-planar imaging (EPI) sequence are presented. In a study of 10 healthy volunteers, the obtained rotationally invariant anisotropy information is compared to the results obtained by the rotationally dependent methods. The water diffusivity in the direction parallel to the fibers was found to be almost 2.5 times higher than the average diffusivity in directions perpendicular to the fibers and showed cylindrically symmetric anisotropy characteristics. The influence of partial volume effects and the point spread function on the measured results was evaluated, and it was the concluded that a resolution of 1 mm in the read and phase directions is required to obtain unbiased values. Possible clinical implications were demonstrated by investigating the diffusion characteristics of 10 patients suffering from narrowing of the cervical canal. The changes in the diffusion characteristics were found to be large enough to allow a robust detection of diffusion changes in the spine, even in cases in which conventional T(2) and T(1) weighted images were unable to detect any lesion.

Differences between neonates and adults in the urokinase-plasminogen activator (u-PA) pathway of the fibrinolytic system

This study deals with plasminogen activation kinetics of fetal and adult Glu-plasminogen types 1 and 2 as well as fetal and adult Lys-plasminogen by urokinase in the presence and absence of the lysine analogues epsilon-amino-n-caproic acid (EACA) and tranexamic acid. In addition, activation kinetics of single-chain urokinase-plasminogen activator (scu-PA) by adult and fetal plasmin types were investigated in the absence and presence of soluble fibrin. All Lys-plasminogen isoforms were more readily activated by urokinase than their corresponding Glu-plasminogen types. No substantial differences of the catalytic constants of urokinase-catalyzed plasminogen activation could be obtained when all fetal plasminogen types were compared to the respective adult types. In the case of all Glu-plasminogen isoforms, EACA as well as tranexamic acid first stimulated the activation process and, at higher concentrations, showed inhibitory properties. Again, the relative ability of all fetal plasminogen types to interact with lysine analogues revealed no differences compared to the respective adult glycoforms. In the absence of soluble fibrin, the catalytic efficiency of scu-PA activation by plasmin was significantly lower for both fetal plasmin isoforms. However, there were no differences in catalytic efficiency between fetal and adult plasmin types in the presence of 4 microM soluble fibrin. In conclusion, no substantial differences exist in urokinase-catalyzed plasminogen activation between neonates and adults, which is in contrast to reported data on plasminogen activation by tissue-type plasminogen activator. In the absence of soluble fibrin, scu-PA activation by fetal plasmin is markedly slower than by adult plasmin. However, this is compensated when fibrin is added at a concentration that is close to the physiological fibrinogen concentration in plasma. It can be summarized that the differences in carbohydrate structures of fetal and adult plasminogen are not associated with major differences in the global function of this part of fibrinolysis, despite functional alterations of scu-PA activation.

Fluid sorption of orthopedic grade ultrahigh molecular weight polyethylene in a serum environment is affected by the surface area and sterilization method

It is shown in this work that lubricant sorption in ultrahigh molecular weight polyethylene (UHMWPE) increases with available surface area of the component. This has clinical relevance, because sliding and articulation experienced in simulator studies can result in changes in surface roughness and the creation of new surfaces. This study compares the fluid sorption of orthopedic grade UHMWPE with different surface areas (but equivalent volume) for different sterilization methods. For both the gamma radiation and nonsterile control samples, the gain in total fluid absorbed scaled proportionately with surface area. For the EtO sterilization treatment, the fluid gain was nonlinear and substantially less than the radiated and control groups. The findings from this study clearly indicate that the sterilization and surface area affect the fluid uptake and weight gain of UHMWPE.

Paravertebral and intraspinal malposition of transfemoral central venous catheters in newborns

We report permanent tetraplegia in a newborn resulting from intraspinal malposition of a transfemoral catheter. In 2 other neonates paravertebral malposition of indwelling Silastic lines was detected. We suggest that left-sided transfemoral catheterization and conditions enhancing collateral flow through the vertebrolumbar pathway may predispose to inadvertent paravertebral catheter placement.

Hemostatic changes following the modified Fontan operation (total cavopulmonary connection)

Thromboembolism is a serious complication after Fontan operation, which may be caused by alterations of the coagulation system. We therefore investigated pro- and anticoagulant factors in 20 patients aged 4 to 21 years, 4 to 63 months following total cavopulmonary connection. Furthermore we compared markers of thrombin activation and fibrinolysis and in vitro clotting and clot-lysis to age-matched healthy subjects. Compared to results of age-matched controls, the Fontan operated individuals had significant decreases in levels of protein C (0.88 U/ml in controls, 0.67 U/ml in patients; p <0.001) and protein S (1.05 in controls, 0.93 U/ml in patients; p <0.05). Moreover, half of the patients had high values of FVIII (>1.5 IU/ml), which are associated with an increased thrombotic risk. These changes may result in enhanced generation of thrombin and plasmin, indicated by our finding of increased thrombin-antithrombin III (TAT) and plasmin-antiplasmin (PAP) levels and a similar trend in prothrombin fragments F1+2. Clot lysis tests, global coagulation tests, red blood cell count, liver enzymes AST, ALT, but not GGT, were generally within the normal ranges.