Frequent ongoing T-cell receptor rearrangements in childhood B- precursor acute lymphoblastic leukemia: implications for monitoring minimal residual disease

Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL.     

A review of applications of MRI in soft tissue and bone tumors

Due to excellent soft tissue contrast and multiplanar imaging capability, MRI is assuming a major role in recognition, staging, and treatment planning of soft tissue and bone tumors. Direct sagittal, coronal, and axial images permit assessment of intraosseous and extraosseous extension of tumors and their relationship to the joints and neurovascular structures, and detection of "skip" lesions. MRI allows improved detection of recurrent tumors in the presence of non-ferromagnetic metallic implants as compared to CT. In the evaluation of soft tissue tumors, MRI is more sensitive than CT and allows differentiation among fat, muscle, tendon, bone, and vascular structures based on signal characteristics. Over a period of 18 months, 100 soft tissue masses and bone tumors were evaluated using MRI. Spin echo sequences with T1 and T2 weighted images were most valuable in differentiating normal and abnormal tissues. Calculated comparative measurements of relaxation times showed no reliable difference between benign and malignant tumors.     

Spermicidal activity of chelated complexes of bis(cyclopentadienyl)vanadium(IV)

Transition metal complexes containing vanadium IV have been shown to modulate the cellular redox potential and catalyse the generation of reactive oxygen intermediates (ROI). Since sperm function is exquisitely susceptible to ROI, we examined the effects of stable chelate complexes of vanadocenes on human sperm motility. We synthesized seven structurally distinct chelate complexes of bis(cyclopentadienyl)vanadium(IV) with bidentate ligands [i.e. vanadocene acetylacetonato monotriflate (VDacac), vanadocene hexafluoro acetylacetonato monotriflate (VDHfacac), vanadocene N-phenyl benzohydroxamato monotriflate (VDPH), vanadocene acethydroxamato monotriflate (VDH), vanadocene catecholate (VDCAT), vanadocene bipyridino ditriflate (VDBPY), and vanadocene dithiocarbamate monotriflate (VDDTC)], and evaluated their spermicidal activity using computer-assisted sperm analysis (CASA; Hamilton-Thorne). All seven chelate complexes of vanadocene elicited potent spermicidal activity at micromolar concentrations (EC50 values: 3.9-106 microM) without affecting the sperm acrosome integrity. The catecholate and acetylacetonate complexes of vanadocene were the most active and the bipyridyl complex the least active with an order of efficacy VDCAT > VDacac > VDDTC > VDPH > VDH > VDHfacac > VDBPY. The spermicidal activity of chelate complexes of vanadocenes was rapid and irreversible since the treated spermatozoa underwent apoptosis, as determined by the flow cytometric analysis of mitochondrial membrane potential, surface annexin V binding assay, in-situ nick-end labelling of sperm nuclei, and confocal laser scanning microscopy. These results provide unprecedented evidence that chelate complexes of vanadocene with bidentate ligands have spermicidal and apoptosis inducing properties. These vanadocene complexes, especially VDacac, may be useful as contraceptive agents.      

The stability of methacrylate biomaterials when enzyme challenged: kinetic and systematic evaluations

This study addressed whether methacrylate monomers and polymers used in dentistry might degrade from enzymolysis by acetylcholinesterase (ACHE), cholesterol esterase (CHE), porcine liver esterase (PRLE), and a pancreatic lipase (PNL). Short (hour) and long-term (day) exposures were performed. Product ratios were used to determine surface hydrolysis of the polymeric materials. Enzyme kinetics were studied for the monomers when challenged by ACHE, CHE, and PRLE. In the case of PRLE, the V(max) for the dimethacrylate substrates varied slightly, but amounted to as much as 10% of that of p-nitrophenylacetate. The K(m) for triethylene glycol dimethacrylate (TEGDMA) was 197 microM for ACHE and 1107 microM for CHE. The V(max) was 2.7 nmol/min for ACHE and 3.5 nmol/min for CHE. TEGDMA was converted by CHE at 2% the rate of cholesteryl oleate. Long-term incubations of monomers with CHE and ACHE produced degrees of hydrolysis that evidenced structure dependency in the ability of the enzymes to effect hydrolysis. Particularly resistant were aromativ derivatives and those with branching in methacrylate linkages. Overall, the study confirms the ability of physiologically important esterases to catalyze the hydrolysis of biomaterial methacrylates.     

Pathogen and resistance spectrum in intraoral infections of the jaw-facial area with special reference to anaerobic bacteria]

The aim of the study was to obtain more knowledge about the aerobic and anaerobic species causing maxillofacial infections and their resistance patterns today. Samples of pus or infectious tissue obtained from 110 patients of maxillofacial surgery were investigated microbiologically by means of aerobic and anaerobic cultivation. After incubation, the cultivated species were isolated and identified. The resistance patterns of all bacteria to penicillin, doxycyclin, and clindamycin were determined. Additionally, the resistance of aerobic species to cefuroxim was documented, and the MICs of cefoxitin and metronidazole to the anaerobic species were assessed. The most frequent disease was periodontitis apicalis (70 patients). Aerobic species alone were found in 23% of the samples, 14% of the infections harbored only anaerobes, but 63% were mixed infections caused by aerobic and anaerobic bacteria. In case of detection of aerobic species, streptococci were always identified. Five patients were infected by Staphylococcus aureus and gram-negative aerobic rods were found in eight patients. Most of the anaerobic species were black pigmented prevotella species (62), nonpigmented prevotellae (56), and fusobacteria (37). Metronidazole and clindamycin were highly efficient to gram-negative anaerobic rods. Most of the oral species were resistant to penicillin and doxycyclin. The indication for applying antibiotics should always be noticed and these drugs should only be used after determination of the pathogenic microorganisms and their susceptibility to the antimicrobials.     

Regulation of erythropoietin production in a human hepatoblastoma cell line

Production of immuno and biologically active erythropoietin was documented to occur in the human hepatoblastoma cell line HepG-2. The expression of the erythropoietin gene was further verified by Northern blot analysis using a single stranded RNA probe. In vitro studies showed that erythropoietin production by these cells was not stimulated by hypoxia or cobalt chloride, but was related to the proliferative activity of the cells in culture. In addition it was found that the secretion of erythropoietin was almost completely abrogated by tunicamycin, an inhibitor of N-linked glycosylation. This effect of tunicamycin was also observed in a permanently transfected cell line that secretes erythropoietin in large quantities.