Biomedical subjects

M Maas

Publications and source records attributed to M Maas.

At least 19 recordsLinked to original sources

PubMed2006

[Expression of angiotensin I converting enzyme in pulmonary hypertension].

We studied angiotensin I converting enzyme (ACE) expression in lung tissue from patients with different forms of pulmonary hypertension (PH) in comparison with that from morphologically normal lung specimens. ACE antigen expression was analysed by immunohistochemistry in morphologically normal lung tissue from 33 patients (19 males, 32-77 years; 14 females, 34-93 years) and compared to that in specimens from 94 patients (67 males, 30-97 years; 27 females: 27-90 years) with different clinically proven forms of PH (according to Venedig classification). Type specific vessel expression pattern as described for normal lung tissue was generally intensified in arteries, arterioles and capillaries of the lung specimens with PH. Specimens with PH due to left heart disease and chronic obstructive pulmonary disease (COPD) showed only very weak or no augmented arterial ACE expression, while PH due to collagenoses or interstitial lung disease showed significantly higher ACE expression. In human PH there is--comparable to animal models--a raised ACE expression in pulmonary lung vessels, with differences between the various forms of PH. These differences in ACE expression may be relevant for subtly differentiated therapeutic anti-ACE therapy regimes.

Adult↗

PubMed2005

Identification and use of biomarkers in Gaucher disease and other lysosomal storage diseases.

UNLABELLED: The value of biomarkers in the clinical management of lysosomal storage diseases is best illustrated by the present use of plasma chitotriosidase levels in the diagnosis and monitoring of Gaucher disease. The enzyme chitotriosidase is specifically produced and secreted by the pathological storage macrophages (Gaucher cells). Plasma chitotriosidase levels are elevated on average 1000-fold in symptomatic patients with Gaucher disease and reflect the body burden on storage cells. Changes in plasma chitotriosidase reflect changes in clinical symptoms. Monitoring of plasma chitotriosidase levels is nowadays commonly used in decision making regarding initiation and optimization of costly therapeutic interventions (enzyme replacement therapy or substrate reduction therapy). A novel substrate has been developed that further facilitates the measurement of chitotriosidase in plasma samples. Moreover, an alternative Gaucher-cell marker, CCL18, has been very recently identified and can also be employed to monitor the disease, particularly in those patients lacking chitotriosidase due to a genetic mutation. There is a need for comparable surrogate markers for other lysosomal storage diseases and the search for such molecules is an area of intense investigation. CONCLUSION: The use of biomarkers can provide valuable insight into the molecular pathogenesis of LSDs, such as Gaucher disease and Fabry disease.

Biomarkers↗

PubMed2005

Prospective study on diagnostic strategies in osteochondral lesions of the talus. Is MRI superior to helical CT?

Our aim in this prospective study was to determine the best diagnostic method for discriminating between patients with and without osteochondral lesions of the talus, with special relevance to the value of MRI compared with the new technique of multidetector helical CT. We compared the diagnostic value of history, physical examination and standard radiography, a 4 cm heel-rise view, helical CT, MRI, and diagnostic arthroscopy for simultaneous detection or exclusion of osteochondral lesions of the talus. A consecutive series of 103 patients (104 ankles) with chronic ankle pain was included in this study. Of these, 29 with 35 osteochondral lesions were identified. Twenty-seven lesions were located in the talus. Our findings showed that helical CT, MRI and diagnostic arthroscopy were significantly better than history, physical examination and standard radiography for detecting or excluding an osteochondral lesion. Also, MRI and diagnostic arthroscopy performed better than a mortise view with a 4 cm heel-rise. We did not find a statistically significant difference between helical CT and MRI. Diagnostic arthroscopy did not perform better than helical CT and MRI for detecting or excluding an osteochondral lesion.

Adolescent↗

PubMed2004

Tumour necrosis factor alpha blockade in treatment resistant pigmented villonodular synovitis.

BACKGROUND: Pigmented villonodular synovitis (PVNS) is considered to be a neoplastic-like disorder of the synovium histologically characterised by villonodular hyperplasia, resulting in dense fibrosis and haemosiderin deposition. The pathogenesis of the disease is still unknown. CASE REPORT: A patient presented with severe treatment resistant PVNS of the right knee joint. Several conventional treatment regimens, including open surgical synovectomy and intra-articular injections of yttrium-90 ((90)Y) failed to control the disease. After finding marked tumour necrosis factor alpha (TNF alpha) expression in arthroscopic synovial tissue samples, treatment with an anti-TNF alpha monoclonal antibody (infliximab) at a dose of 5 mg/kg was started. Additional courses with the same dose given 2, 6, 14, and 20 weeks later, and bimonthly thereafter up to 54 weeks, controlled the signs and symptoms. Immunohistological analysis at follow up identified a marked reduction in macrophage numbers and TNF alpha expression in the synovium. DISCUSSION: This is probably the first case which describes treatment with TNF alpha blockade of PVNS in a patient who is refractory to conventional treatment. It provides the rationale for larger controlled studies to elucidate further the efficacy of TNFalpha blockade treatment in refractory PVNS.

Adult↗

PubMed2004

Sustained therapeutic effects of oral miglustat (Zavesca, N-butyldeoxynojirimycin, OGT 918) in type I Gaucher disease.

It has been shown that treatment with miglustat (Zavesca, N-butyldeoxynojirimycin, OGT 918) improves key clinical features of type I Gaucher disease after 1 year of treatment. This study reports longer-term efficacy and safety data. Patients who had completed 12 months of treatment with open-label miglustat (100-300 mg three times daily) were enrolled to continue with therapy in an extension study. Data are presented up to month 36. Liver and spleen volumes measured by CT or MRI were scheduled every 6 months. Biochemical and haematological parameters, including chitotriosidase activity (a sensitive marker of Gaucher disease activity) were monitored every 3 months. Safety data were also collected every 3 months. Eighteen of 22 eligible patients at four centres entered the extension phase and 14 of these completed 36 months of treatment with miglustat. After 36 months, there were statistically significant improvements in all major efficacy endpoints. Liver and spleen organ volumes were reduced by 18% and 30%, respectively. In patients whose haemoglobin value had been below 11.5 g/dl at baseline, mean haemoglobin increased progressively from baseline by 0.55 g/dl at month 12 (NS), 1.28 g/dl at month 24 (p =0.007), and 1.30 g/dl at month 36 (p =0.013). The mean platelet count at month 36 increased from baseline by 22 x 10(9)/L. No new cases of peripheral neuropathy occurred since previously reported. Diarrhoea and weight loss, which were frequently reported during the initial 12-month study, decreased in magnitude and prevalence during the second and third years. Patients treated with miglustat for 3 years show significant improvements in organ volumes and haematological parameters. In conclusion, miglustat was increasingly effective over time and showed acceptable tolerability in patients who continued with treatment for 3 years.

1-Deoxynojirimycin↗

PubMed2004

Increased external tibial torsion and osteochondritis dissecans of the knee.

In the past, osteochondritis dissecans of the knee was associated with increased tibial exotorsion, established with a clinical measuring method. Now the gold standard for determining tibial torsion is computed tomography. The aim of the current study was to establish whether the abovementioned association could be confirmed in the current patients, measured with computed tomography. Confounding aberrations of femoral torsion were ruled out. Twenty-three patients with osteochondritis dissecans in 27 knees were treated between 1991 and 1999. Symptoms and treatment results were comparable with those reported in the literature. Femoral and tibial torsion were measured with a computed tomography scan. The average femoral antetorsion was comparable with that in the literature. The average tibial exotorsion was significantly higher than the control value. Exotorsion was increased more in patients with bilateral osteochondritis, and extremely high in patients with persisting complaints. Increased tibial exotorsion could play a role in development of osteochondritis dissecans of the knee. Extreme exotorsion might be prognostic for persistent complaints.

Adolescent↗

PubMed2003

Vascular malformations of the lower limb with osseous involvement.

Vascular malformations are rare congenital lesions which often have associated skeletal changes. Over a period of ten years, 90 patients at our clinic had a vascular anomaly of the lower limb, examined by either CT or MRI. Of these, 18 (20%) had bony involvement. A questionnaire was sent to these patients (8 men, 10 women) to evaluate their age of presentation, initial symptoms and current complaints. Radiological imaging revealed 15 low- and three high-flow lesions. The mean age at presentation to a physician was six years of age. Pain was the most common complaint. Disparity in leg length of 2 cm or more was observed in ten patients. Of the 16 patients with muscle infiltration, 13 had four or more muscles involved. Treatment by resection alone would require radical surgery.

Adolescent↗

PubMed2002

Oblique radiograph for the detection of bone spurs in anterior ankle impingement.

OBJECTIVE: The aim of this study was to develop a radiographic view to detect anteromedial talotibial osteophytes that remain undetected on standard radiographs. DESIGN AND PATIENTS: In 10 cadaver specimens the maximal size was measured of anteromedial tibial osteophytes that remain undetected on a standard lateral radiograph projection, due to the presence of the anteromedial tibial rim. The average projection of the most prominent anterolateral tibial rim over the anteromedial rim was found to be 7.3 mm. A 7 mm barium-clay osteophyte was attached to this anteromedial rim of the distal tibia. Anteromedial osteophytes become most prominent on an oblique view, in which the radiographic beam is tilted into a 45 degrees craniocaudal direction with the leg in 30 degrees external rotation. This oblique view was compared with the findings of arthroscopic surgery in 25 consecutive patients with anterior ankle impingement syndrome. RESULTS: Medially located tibial and talar osteophytes remained undetected on a standard lateral projection and became visible on the oblique anteromedial impingement (AMI) radiograph. Anterolateral tibial and talar osteophytes were well detected on a standard lateral radiograph projection but were invisible on the AMI view. There was a high correlation between the location of the osteophyte and the location of symptoms and the findings at arthroscopy. CONCLUSION: A combination of lateral and oblique radiographs can be used to differentiate between anteromedial and anterolateral bony ankle impingement.

Adult↗

PubMed2002

[Diagnostic imaging of injuries and overuse in soccer players].

Soccer is one of the most popular sports worldwide. There is a high incidence of injuries in soccer in which several intrinsic and extrinsic factors play a part. Most injuries are minor, self-limiting and do not need extensive medical treatment or imaging. Imaging can be required for several reasons e.g. when the clinical findings are doubtful, to replace arthroscopy (i. e. of the knee) or for prognostic reasons. All imaging modalities available to the radiologist can be used but MRI is the most valuable imaging modality with its superior contrast resolution and multiplanar capabilities. Basically, injuries in the soccer player can occur anywhere in the body like in every sport. The lower extremities, more specific the knee and ankle, are however the most injured parts.

Athletic Injuries↗

PubMed2002

Imaging and quantifying skeletal involvement in Gaucher disease.

Radiological imaging is used in patients with Gaucher disease to estimate the disease burden, to evaluate the presence of specific skeletal complications and to track response to therapy. MRI is currently the best technique for assessing bone marrow involvement in Gaucher disease. Gaucher cell infiltrated bone marrow is characterized by an abnormal low signal intensity on conventional T1- and T2-weighted spin echo sequences, owing to a reduction in fat marrow, which gives a high signal intensity. Enzyme replacement therapy results in a degradation of Gaucher cell deposits with a reconversion of marrow fat and consequently an increased signal on T(1)-weighted images. Conventional MRI also detects other skeletal complications in Gaucher disease, including oedema resulting from acute bone infarction, infection and trauma, avascular necrosis, pathological fractures and vertebral compression. The main drawback of conventional MRI is that it is not quantitative. Quantitative chemical shift imaging is the most sensitive quantitative method for evaluating bone marrow but is not widely available. Alternative MRI-based methods include calculation of the T1 relaxation constant and proton spectroscopy. Scoring of imaging changes detected on conventional MRI may be useful in estimating disease burden and risk of complications. Dual-energy X-ray absorptiometry (DXA) is sensitive to generalized osteopenia and changes in bone mineral density with extended enzyme replacement therapy. However, DXA is insensitive to local changes and cannot yet be used to predict fracture risk in these patients. Until the ideal quantitative technique is developed, conventional MRI will remain the best diagnostic modality for assessing skeletal complications in Gaucher disease and monitoring response to enzyme replacement therapy.

Absorptiometry, Photon↗

PubMed2002

Response of Gaucher bone disease to enzyme replacement therapy.

In Gaucher disease, enzyme replacement therapy usually reduces liver and spleen volumes and improves haematological abnormalities within 1 year. In contrast, skeletal manifestations of Gaucher disease are thought to respond more slowly. For example, decreased bone marrow glycolipid infiltration and increased bone mineral density have been reported to take up to 3-4 years of treatment. In this report, we present recent studies using T1- and T2-weighted MRI and quantitative chemical shift imaging that demonstrate decreases in abnormal glucocerebroside infiltration and increases in normal fat content of bone marrow within the first year of treatment. There was no obvious relationship between age, gender, splenectomy status or genotype and the response of bone marrow to therapy. Although the dose of enzyme replacement therapy may be related to bone marrow response, no significant relationship was demonstrated in this report. Long-term enzyme replacement therapy induces continued degradation of Gaucher cell deposits, reconversion of fat marrow and increased bone mineral density. This treatment is also associated with improved or non-progressive bone symptoms and functional status in most adult patients, and it prevents the new occurrence of bone pain and bone crisis in nearly all patients. The development of more sensitive, quantitative imaging methods will help to evaluate disease severity better and to assess the response to therapy.

Adolescent↗

PubMed2001

Assessment of ulnar variance: a radiological investigation in a Dutch population.

OBJECTIVE: A radiological study was performed to evaluate ulnar variance in 68 Dutch patients using an electronic digitizer compared with Palmer's concentric circle method. Using the digitizer method only, the effect of different wrist positions and grip on ulnar variance was then investigated. Finally the distribution of ulnar variance in the selected patients was investigated also using the digitizer method. DESIGN AND PATIENTS: All radiographs were performed with the wrist in a standard zero-rotation position (posteroanterior) and in supination (anteroposterior). Palmer's concentric circle method and an electronic digitizer connected to a personal computer were used to measure ulnar variance. The digitizer consists of a Plexiglas plate with an electronically activated grid beneath it. A radiograph is placed on the plate and a cursor activates a point on the grid. Three plots are marked on the radius and one plot on the most distal part of the ulnar head. The digitizer then determines the difference between a radius passing through the radius plots and the ulnar plot. RESULTS AND CONCLUSIONS: Using the concentric circle method we found an ulna plus predominance, but an ulna minus predominance when using the digitizer method. Overall the ulnar variance distribution for Palmer's method was 41.9% ulna plus, 25.7% neutral and 32.4% ulna minus variance, and for the digitizer method was 40.4% ulna plus, 1.5% neutral and 58.1% ulna minus. The percentage ulnar variance greater than 1 mm on standard radiographs increased from 23% to 58% using the digitizer, with maximum grip, clearly demonstrating the (dynamic) effect of grip on ulnar variance. This almost threefold increase was found to be a significant difference. Significant differences were found between ulnar variance when different wrist positions were compared.

Adolescent↗

PubMed2001

Use of magnetic resonance imaging for the evaluation of vascular malformations of the lower extremity.

Vascular malformations are anatomically subdivided according to the predominant channel anomaly into either capillary, arterial, venous, lymphatic, or combinations. They can be further subdivided into high- or low-flow malformations. Any lesion that has an arterial component is considered a high-flow malformation. Once the diagnosis of a vascular malformation is made, it is of paramount importance to define not only the flow characteristics but also the full range of extension, because the prognosis and appropriate treatment vary substantially for each type of anomaly. The two most useful noninvasive imaging techniques for assessing vascular malformations are magnetic resonance imaging (MRI) and ultrasonography. The aim of this review is to give surgeons involved in treating patients with vascular malformations an opportunity to gain some background on MRI scans when assessing vascular malformations. Although MRI is a powerful modality for assessing vascular malformations, we will also discuss some of the limitations of MRI. We further suggest a diagnostic flow chart developed on the basis of MRI features designed to help determine the composition of a vascular birthmark when intervention is anticipated.

Blood Vessels↗

PubMed2001

Magnetic resonance imaging findings of vascular malformations of the lower extremity.

Vascular malformations are congenital lesions resulting from a defect during embryogenesis. Magnetic resonance imaging (MRI) is a very effective method for demonstrating detailed information regarding involved structures, extent, and flow characteristics of vascular malformations. In previous MRI studies, most of the emphasis is laid on the difference between high- and low-flow lesions, whereas little detailed information is available about the extent of local tissue involvement. These additional characteristics may influence the approach in treating these malformations and improve understanding of the pathogenesis. We retrospectively reviewed MRI scans of 40 patients with vascular malformations of the lower extremity. Thirty-four patients had low-flow lesions, and six had high-flow lesions. Of the low-flow lesions, 23 patients (67.6 percent) had muscle infiltration, with four of the six high-flow lesions having muscle infiltration. Nine of the 11 male patients (81.8 percent) with low-flow lesions had associated muscle infiltration, in comparison with 14 of the 23 female patients (60.9 percent) with low-flow lesions (p = 0.206). Eighty percent of the vascular malformations located on the thigh with muscle involvement had involvement of the anterior muscle group, whereas 86.6 percent of the patients with a vascular malformation located on the leg and with associated muscle involvement had at least the posterior muscle group involved (p = 0.0049). Ten patients (25 percent) of the whole group had bone infiltration. Low-flow lesions often had multifocal lesions (20.6 percent), whereas associated muscle atrophy was visible in 10 low-flow lesions and in two high-flow lesions. In low-flow lesions with muscle infiltration (n = 23), 43 percent (n = 10) had associated surrounding muscle atrophy (p = 0.009). Hypertrophy of the subcutaneous tissue was visible in 11 low-flow patients (32.4 percent). The high amount of muscle and bone involvement in vascular malformations of the lower extremity is emphasized with this study. Of particular interest was the difference in affected muscle groups. The angiosome concept is used to explain this preponderance, and we feel the angiosome concept could also be used when assessing possible intervention. The surrounding muscle atrophy and multifocal nature of these anomalies are further important considerations when assessing the possibility of intervention.

Adolescent↗

PubMed2001

Thematic analysis of the experience of making a decision to place a family member with Alzheimer's disease in a special care unit.

The purpose of this study was to provide an in-depth description of the experience of making the decision to place a family member in a special care unit among a diverse sample of family caregivers. To achieve purposive maximum variation of the sample, the sample of 30 family caregivers was chosen from an original study of 256 family caregivers. The sample was randomly stratified according to ethnicity, gender, and relationship to the care receiver. Three independent researchers used Luborsky's method of thematic analysis to analyze the interviews. After mutual consensus, 1565 themes (descriptive statements) were identified and synthesized into 21 topics. The topics were then synthesized into four patterns describing the decision-making experience: moving toward the unavoidable decision, struggling with the decision, seeking reassurance, and remaining connected.

Adult↗

PubMed2001

Clinically relevant therapeutic endpoints in type I Gaucher disease.

The introduction of enzyme supplementation therapy for Gaucher disease has had a great impact on the lives of many patients. Organomegaly, cytopenia and bone disease have been shown to improve in response to treatment, resulting in an improvement in quality of life. However, the assessment of organ system involvement is not always done in such a way that the relationship with clinically relevant endpoints is clear. The lack of adequately validated methods of assessment, especially for bone disease, has hindered the establishment of treatment goals and guidelines for treatment optimization.

Biomarkers↗

PubMed2001

Minnaar type 1 symptomatic lunotriquetral coalition: a report of nine patients.

Coalition of carpal bones is relatively common. It most frequently involves the lunate and triquetrum. This finding is almost always coincidental and asymptomatic. The fusion also can be incomplete, however, resembling a pseudarthrosis, and these patients can become symptomatic. To the best of our knowledge only 6 patients with a symptomatic Minnaar type 1 lunotriquetral coalition have been described in the literature. We present an additional nine symptomatic patients (12 wrists) with this type of coalition. A lunotriquetral arthrodesis was performed in 5 cases. In 3 cases a proximal row carpectomy was performed.

Adult↗

PubMed2001

Randomized clinical trial of a quality improvement intervention in nursing homes.

PURPOSE: The purpose of the study was to determine if simply providing nursing facilities with comparative quality performance information and education about quality improvement would improve clinical practices and subsequently improve resident outcomes, or if a stronger intervention, expert clinical consultation with nursing facility staff, is needed. DESIGN AND METHODS: Nursing facilities (n = 113) were randomly assigned to one of three groups: workshop and feedback reports only, workshop and feedback reports with clinical consultation, and control. Minimum Data Set (MDS) Quality Indicator (QI) feedback reports were prepared and sent quarterly to each facility in intervention groups for a year. Clinical consultation by a gerontological clinical nurse specialist (GCNS) was offered to those in the second group. RESULTS: With the exception of MDS QI 27 (little or no activity), no significant differences in resident assessment measures were detected between the groups of facilities. However, outcomes of residents in nursing homes that actually took advantage of the clinical consultation of the GCNS demonstrated trends in improvements in QIs measuring falls, behavioral symptoms, little or no activity, and pressure ulcers (overall and for low-risk residents). IMPLICATIONS: Simply providing comparative performance feedback is not enough to improve resident outcomes. It appears that only those nursing homes that sought the additional intensive support of the GCNS were able to effect enough change in clinical practice to improve resident outcomes significantly.

Aged↗