Interaction of kinesin motors, microtubules, and MAPs

Kinesins are a family of microtubule-dependent motor proteins that carry cargoes such as vesicles, organelles, or protein complexes along microtubules. Here we summarize structural studies of the "conventional" motor protein kinesin-1 and its interactions with microtubules, as determined by X-ray crystallography and cryo-electron microscopy. In particular, we consider the docking between the kinesin motor domain and tubulin subunits and summarize the evidence that kinesin binds mainly to beta tubulin with the switch-2 helix close to the intradimer interface between alpha and beta tubulin.

Synthesis of oligonucleotides bearing an arylamine modification in the C8-position of 2'-deoxyguanosine

C8-Arylamine-dG adducts were converted into their corresponding 5-O-DMTr-3'-O-phosphoramidite-C8-arylamine-dG derivatives. These compounds were used for the automated synthesis of site-specifically modified oligonucleotides. The oligonucleotides were studied for their CD properties, Tm values, and their effects on primer extension assays using human DNA-polymerase beta.

Impact of corticosteroids on the immune response to a MF59-adjuvanted influenza vaccine in elderly COPD-patients

The influence of steroids on the antibody response to a MF59-adjuvanted influenza vaccine in elderly COPD patients has not been studied previously. In the influenza season 2001/02 (October-February) elderly COPD patients were recruited at 14 doctor's offices and our 250-bed hospital. Patients were stratified into three groups according to current treatment regimen: (a) > 10 mg of prednisolone/day (SS); (b) inhaled steroids (IS); (c) no steroid treatment (control group, CG). All patients were vaccinated with the MF59-adjuvanted influenza vaccine. Antibodies against the influenza strains A/H1N1, A/H3N2, and B were measured at baseline, 4 and 24 weeks after vaccination by hemagglutination inhibition (HI) assay. One-hundred and sixty-two patients completed the study (CG n = 42; IS n = 87; SS n = 33). Mean age was 71.3 years (range 60-89). Twenty-one percent of all patients reported local reactions; no serious adverse events were observed. Four weeks after vaccination, mean geometric HI titres (GMT) for A/H1N1, A/H3N and B increased significantly in all groups (p < or = 0.05). After 24 weeks, GMTs to A/H1N1 and A/H3N2 returned to baseline, while GMTs to type B remained significantly higher than baseline in all groups. Significant differences between the groups as regards GMTs, seroconversion (56-89%) or seroprotection rates (64-93%) were not observed. Systemic steroids did not influence the antibody response towards the MF59-adjuvanted influenza vaccine. We found that the strains included in the vaccine showed varying long-term immunogenicity.

Nucleotide analogues as probes for DNA polymerases

Transmission of the genetic information from the parental DNA strand to the offspring is crucial for the survival of any living species. In nature, all DNA synthesis in DNA replication, recombination and repair is catalyzed by DNA polymerases and depends on their ability to select the canonical nucleobase pair from a pool of structurally similar building blocks. Recently, a wealth of valuable new insights into DNA polymerase mechanisms have been gained through application of carefully designed synthetic nucleotides and oligonucleotides in functional enzyme studies. The applied analogues exhibit features that differ in certain aspects from their natural counterparts and, thus, allow investigation of the involvement and efficacy of a chosen particular aspect on the entire complex enzyme mechanism. This review will focus on a depiction of the efforts that have been undertaken towards the development of nucleotide analogues with carefully altered properties. The different approaches will be discussed in the context of the motivation and the problem under investigation.

Cooperative activation of transcription by autoimmune regulator AIRE and CBP

Autoimmune regulator (AIRE) is a transcriptional regulator that is believed to control the expression of tissue-specific genes in the thymus. Mutated AIRE is responsible for onset of the hereditary autoimmune disease APECED. AIRE is able to form nuclear bodies (NBs) and interacts with the ubiquitous transcriptional coactivator CBP. In this paper, we show that CBP and AIRE synergistically activate transcription on different promoter reporters whereas AIRE gene mutation R257X, found in APECED patients, interferes with this coactivation effect. Furthermore, the overexpression of AIRE and CBP collaboratively enhance endogenous IFNbeta mRNA expression. The immunohistochemical studies suggest that CBP, depending on the balance of nuclear proteins, is a component of AIRE NBs. We also show that AIRE NBs are devoid of active chromatin and, therefore, not sites of transcription. In addition, we demonstrate by 3D analyses that AIRE and CBP, when colocalizing, are located spatially differently within AIRE NBs. In conclusion, our data suggest that AIRE activates transcription of the target genes, i.e., autoantigens in collaboration with CBP and that this activation occurs outside of AIRE NBs.

[Reconstruction of the tibial diaphysis with transfer of the tibial head onto the proximal fibula. Follow-up after 63 years]

Osteoarthritis of the knee is often diagnosed in the orthopedic trauma practice. One major cause is axial deformity with overload. In the case presented here osteomyelitis of the tibial diaphysis developed in childhood. Surgical treatment consisted of resection of the middle tibial third and transferring the tibial head onto the proximal fibula. In this way it was possible to eradicate the osteomyelitis of the lower leg and to achieve osseous consolidation between the tibia and fibula. Despite the significant shortening of the lower limb and the varus axial deformity, the knee joint function was satisfactory in the subsequent development. After a long interval without symptoms the patient developed a medially accentuated osteoarthritis of the knee.

Composite marginal zone B-cell lymphoma and classical Hodgkin's lymphoma: a clinicopathological study of 12 cases

AIMS

Classical Hodgkin's lymphoma (cHL) rarely coexists as composite lymphoma with B-cell non-Hodgkin's lymphoma (B-NHL). We characterized 12 cases of composite marginal zone B-cell lymphoma (MZBL) and cHL by immunohistochemistry and molecular biology.

METHODS AND RESULTS

Eight patients had gastric MZBL of mucosa-associated lymphoid tissue (MALT)-type, in five cases with a diffuse large B-cell lymphoma component. Concurrent cHL was observed either in the stomach wall, regional, or distant lymph nodes. One patient each had composite pulmonary/thyroid MZBL of MALT-type and cHL. In two cases, nodal composite MZBL and cHL was observed. cHL displayed features of mixed cellularity type in 10 cases, while in two cases only scattered Hodgkin- and Reed-Sternberg (H/RS) cells were noted. H/RS cells expressed CD30, multiple myeloma oncogene 1 protein (MUM1P), p53 (100%), CD15 (58%), CD20 (58%) and Epstein-Barr virus-associated LMP1 (50%). No t(11;18)(q21;q21) was detected in composite MZBL of MALT-type and cHL.

CONCLUSIONS

MZBL and cHL may occur as composite lymphoma, possibly reflecting clonal lymphoma progression. Derivation from extranodal MZBL of MALT-type should be excluded in cases in which a diagnosis of primary extranodal cHL is considered.

Apoptosis and proliferation in lungs of human fetuses exposed to chorioamnionitis

AIMS

To determine whether chorioamnionitis has an impact on the extent of apoptosis and proliferation in fetal lungs. Fetuses exposed to chorioamnionitis have an increased risk of aquiring lung tissue damage in utero.

METHODS AND RESULTS

Lung tissue sections from 35 stillborn fetuses were used in this study. Chorioamnionitis-exposed fetuses were subdivided depending on whether pneumonia was diagnosed (n = 13) or not (n = 10); 12 unaffected fetuses served as controls. Apoptotic and proliferating cells were determined by in-situ terminal deoxytransferase-mediated dUTP nick end labelling (TUNEL) assay and by anti-Ki67 immunohistochemistry, and quantified. The median apoptotic index in lungs of chorioamnionitis-exposed fetuses increased 2.4-fold compared with chorioamnionitis-negative stillborn controls (P = 0.043) and rose 21.6-fold when chorioamnionitis-exposed fetuses additionally developed pneumonia (P < 0.001). Compared with the proliferation index of the control group (PI = 2.3), the median percentage of proliferating cells in the lungs of chorioamnionitis-exposed fetuses decreased (PI = 1.4) (P = 0.036), but increased 1.8-fold (P = 0.036) in fetal lungs of the chorioamnionitis/pneumonia group. By double labellings combining the TUNEL assay or the Ki67 antigen with cell marker proteins, we identified distal airway epithelial cells as the cell type undergoing apoptosis in chorioamnionitis-exposed fetal lungs, while epithelial, endothelial and smooth muscle cells proliferated. Immunolabellings of cleaved caspases -8 and -9 revealed that apoptosis is mediated via initiator caspase-8.

CONCLUSION

Chorioamnionitis induces apoptosis of distal airway epithelial cells via the caspase-8 pathway and interferes with the normal proliferative activity of epithelial, endothelial, and smooth muscle cells in fetal lungs. Thus, apoptosis and proliferation are an important feature of chorioamnionitis-associated lung injury in utero.

The structure of microtubule motor proteins

Microtubules are the intracellular tracks for two classes of motor proteins: kinesins and dyneins. During the past few years, the motor domain structures of several kinesins from different organisms have been determined by X-ray crystallography. Compared with kinesins, dyneins are much larger proteins and attempts to crystallize them have failed so far. Structural information about these proteins comes mostly from electron microscopy. In this chapter, we mainly focus on the crystal structures of kinesin motor domains.

[Anaplastic large cell lymphomas lack the expression of T-cell receptor molecules]

Anaplastic large cell lymphoma (ALCL) designates a heterogeneous group of CD30+ (systemic or primary cutaneous) peripheral T-cell lymphomas (PTCLs). A subgroup of systemic ALCL is transformed by anaplastic lymphoma kinase (ALK). We compared 46 ALCL with 22 PTCLs in terms of T-cell receptor (TCR) rearrangements, expression of TCRs and TCR-associated molecules [CD3, ZAP-70 (zeta-associated protein 70)]. Despite their frequent clonal rearrangement for TCRbeta, only 4% of ALCLs expressed TCRbeta protein, whereas TCRs were detected in 86% of PTCLs. Moreover, both TCRbeta+ ALCLs lacked CD3 and ZAP-70 (ie, molecules indispensable for the transduction of cognate TCR signals). Defective expression of TCRs is a common characteristic of all types of ALCL, which may contribute to the dysregulation of intracellular signaling pathways controlling T-cell activation and survival. This molecular hallmark of ALCL is analogous to defective immunoglobulin expression distinguishing Hodgkin lymphoma from other B-cell lymphomas.

Expression of stromelysin-1 (MMP-3), gelatinase B (MMP-9), and plasminogen activator system during fetal calvarial development

AIMS

To investigate whether degrading proteases can be found in patent calvarial sutures. Sutural growth and fusion means replacement of the sutural connective tissue, rich in fibronectin and collagen type V, by expanding calvarial bone. Proliferation of one tissue into the border area of another implies the presence of enzymes able to degrade extracellular matrix (ECM). An important family of proteases is the matrix metalloproteinases (MMPs), as is the plasminogen/plasmin system.

METHODS AND RESULTS

Expression of two MMPs with substrate specifity for fibronectin and collagen type V and of the plasminogen activator system was studied by immunohistochemistry in samples of human fetal calvariae (age range weeks 19-35 of gestation). In all cases, intense staining for MMPs, urokinase, and urokinase receptor was found in the sutural connective tissue and along the outer and inner borders of calvarial bone.

CONCLUSIONS

Our findings suggest that degradation of sutural connective tissue takes place during sutural growth. This might facilitate proliferation of calvarial bone. Recently, it was shown that an important regulatory mechanism of sutural growth is apoptosis of osteoblasts in the osteogenic front. Intact fibronectin is known to prevent apoptosis of proliferating osteoblasts while fibronectin degradation induces their apoptosis.

Development of granulomatous common variable immunodeficiency subsequent to infection with Toxoplasma gondii

Common variable immunodeficiency (CVID) is a heterogeneous immunodeficiency that is accompanied by granulomatous lesions in 5-10% of cases. Why some patients develop granulomatous disease remains unclear. Here we describe a 12-year-old previously healthy girl who presented with pancytopenia and granulomatous lymphoproliferation subsequent to infection with Toxoplasma gondii. Loosely arranged non-fibrosing granulomas were observed in the liver, lymph nodes and lung, but no Toxoplasma tachyzoites could be demonstrated and polymerase chain reaction (PCR) and culture were negative for Toxoplasma and a wide range of other pathogens. While the patient had a normal peripheral B cell status at presentation, the development of CVID could be observed during the following months, leading to a loss of memory B cells. This was accompanied by an increasingly activated CD4(+) T cell compartment and high serum levels of angiotensin-converting enzyme (ACE), tumour necrosis factor (TNF) and sCD25. Steroid therapy reduced pancytopenia, granulomatous lymphoproliferation and cytokine elevations, but did not improve the B cell status. This is the first report of an association of Toxoplasma infection with granulomatous CVID and provides one of the rare examples where the onset of CVID could be documented subsequent to an infectious disease.

[Cup placement in hip replacement surgery -- A comparison of free-hand and computer assisted cup placement in total hip arthroplasty -- a multi-center study]

AIM

The purpose of the current study was to determine the accuracy of free hand and computer-assisted (CAS) cup placement.

MATERIAL AND METHODS

Between June 1985 and August 2001, 105 free-hand and from March to November 1999 80 total hip arthroplasties under computer assistance were implanted in the above mentioned centers. To determine the accuracy of the cups, the inclination and anteversion angles were measured. In all cases the cup position was measured with a CT-investigation of the pelvis. Statistical analysis was performed with the F-test.

RESULTS

With regard to the inclination and anteversion angles the variability of the cup position was significantly higher in the group of free hand implanted cups. In the CAS group we could not find any "extreme" positions.

CONCLUSION

Using computer-assisted surgery a significantly higher reproducible cup position can be obtained. Long time survey may present a lowering of the rate of early and late complications caused by better prostheses alignment in the follow up.

The accuracy of free-hand cup positioning--a CT based measurement of cup placement in 105 total hip arthroplasties

We studied 105 patients who received a total hip arthroplasty between June 1985 and August 2001 using freehand positioning of the acetabular cup. Using pelvic CT scan and the hip-plan module of SurgiGATE-System (Medivision, Oberdorf, Switzerland), we measured the angles of inclination and anteversion of the cup. Mean inclination angle was 45.8 degrees +/-10.1 degrees (range: 23.0-71.5 degrees ) and mean anteversion angle was 27.3 degrees +/-15.0 degrees (range: -23.5 degrees to 59.0 degrees ). We compared the results to the "safe" position as defined by Lewinnek et al. and found that only 27/105 cups were implanted within the limits of the safe position. We conclude that a safe position as defined by Lewinnek et al. [13] was only achieved in a minority of the cups that were implanted freehand.

Hepatoid Thymic Carcinoma

We describe the clinicopathologic findings in a so far unrecognized thymic tumor. The tumor occurred in a 70-year-old woman with respiratory distress but neither myasthenia gravis nor other symptoms. Metastases or another primary tumor were absent. The well-circumscribed neoplasm was located in the thymic region, measured 18 x 12 x 8 cm, and showed a homogeneous, tan-colored, soft cut surface. By histology, the tumor lacked a true capsule and a lobular growth pattern, was almost devoid of stroma, and infiltrated among remnant thymus lobules. The polygonal tumor cells formed solid sheets, trabeculae, or occurred as single cells that resembled hepatocytes. Proliferative activity was low. Portal structures, sinuses, and bile were absent as were areas of conventional thymoma, adenocarcinoma, or germ cell tumor. The tumor expressed cytokeratins 7 and 19, alpha1-antitrypsin, alpha1-antichymotrypsin, and hep-Par-1. Alpha-fetoprotein (AFP), human beta-chorionic gonadotropin (beta-HCG), placental alkaline phosphatase, CD5, CD30, CD31, CD34, CD45, CD68, CD99, S-100, HMB45, desmin, actin, or neuroendocrine markers were not expressed, and intratumorous CD1a+ or TdT+ immature T cells were absent. AFP was repeatedly undetectable in the blood. Mediastinal tumor recurrence was detected 6 months after surgery. Following radiochemotherapy, the patient has remained free of disease for 26 months. We conclude that this tumor is a thymic carcinoma (WHO type C thymoma). A diagnosis of hepatoid yolk sack tumor appears unlikely considering absence of a bona fide germ cell component, lack of AFP expression, and the patient's female gender. Because of its morphologic and immunohistochemical features, we propose the term "hepatoid thymic carcinoma" for this new type of thymic carcinoma.

Apoptosis and proliferation in lungs of ventilated and oxygen-treated preterm infants

Apoptosis and proliferation and the effect of exogenous surfactant on these processes were investigated in the lungs of mechanically ventilated/oxygen-treated preterm infants with respiratory distress syndrome and stillborn foetuses. Apoptotic and proliferation indices were determined in lung tissue sections from 27 ventilated/oxygen-treated preterm infants and 29 stillborn foetuses. The effect of exogenous surfactant on apoptosis and proliferation was studied in 16 ventilated preterm infants; 11 untreated infants served as control. Apoptotic and proliferating cells were identified by double labelling combining terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick end-labelling or Ki-67 with cell marker proteins. Pathways to cell death were explored by immunolabelling of cleaved caspases-3, -8 and -9. In the lungs of ventilated/oxygen-treated preterm infants, the numbers of apoptotic and proliferating cells increased significantly compared to the respective numbers in the lungs of stillborn foetuses. Apoptosis was detected in alveolar epithelial cells, whereas epithelial, endothelial and smooth muscle cells proliferated. Surfactant treatment reduced apoptosis induced by ventilation/oxygen-treatment; however, the decrease was not significant. Caspases-8 and -9 do not contribute to ventilation-induced apoptosis, whereas caspase-3 is involved. In conclusion, ventilation/oxygen-treatment induces epithelial cell apoptosis and proliferation of epithelial, endothelial and smooth muscle cells in the lungs of preterm infants.

[The overexpression of NCAM (CD56) in human hearts is specific for ischemic damage]

The main reason for myocardial dysfunction is chronical myocardial ischemia. Recently we could show, that NCAM (CD56), a neural cell adhesion molecule and member of the immunoglobuline superfamily, and the transcription factor AML1 (RUNX1) are overexpressed in chronic ischemic human heart failure compaired to normal hearts. Here we demonstrate, that the overexpression of NCAM (CD56) is specific for ischemic damage as compaired to other heart diseases including congestive cardiomyopathy, hypertrophic obstrutive cardiomyopathy, myocarditis and sarcoidosis. Concerning the transcriptional regulation of NCAM (CD56) by AML1 (RUNX1) we isolated 3 novel isoforms of AML 1 (RUNX1) with different transactivating function, that might be a regulatory element of the NCAM (CD56) overexpression in chronical myocardial ischemia.

Progressively enlarging paracardial lipoma in a child

Mediastinal lipomas are slowly growing tumours. Only very few cases have been reported in children. None of these included a rapidly enlarging lipoma. We present an 8-year-old severely adipose girl with an incidentally diagnosed mediastinal lipoma that showed rapid enlargement within 7 weeks.