3D azido-bridged cobalt(II) complexes with diazines as coligands

Two new three-dimensional azido-bridged Co(II) compounds with formula [Co(N₃)₂(2,5-Me₂pyz)]_n (1) and [Co(N₃)₂(2-ampym)]_n (2) have been structurally and magnetically characterized. 2,5-Me₂pyz and 2-ampym are 2,5-dimethylpyrazine and 2-aminopyrimidine, respectively. Compound 1 crystallizes in the monoclinic system with space group P2₁/c and compound 2 in the orthorhombic system with space group Pnma. In 1 and 2 each cobalt atom is linked to the four nearest-neighbors by end-to-end (EE) azido bridges, forming square layers. These layers are further connected to 3D networks by the N,N′-bridging ligands 2,5-dimethylpyrazine or 2-aminopyrimidine. The magnetic properties of 1 and 2 are reported. The plots of χ_M or χ_MT for 1 and 2 show antiferromagnetic coupling.     

Infectious Epstein-Barr virus lacking major glycoprotein BLLF1 (gp350/220) demonstrates the existence of additional viral ligands

The binding of the viral major glycoprotein BLLF1 (gp350/220) to the CD21 cellular receptor is thought to play an essential role during infection of B lymphocytes by the Epstein-Barr virus (EBV). However, since CD21-negative cells have been reported to be infectible with EBV, additional interactions between viral and cellular molecules seem to be probable. Based on a recombinant genomic EBV plasmid, we deleted the gene that encodes the viral glycoprotein BLLF1. We tested the ability of the viral mutant to infect different lymphoid and epithelial cell lines. Primary human B cells, lymphoid cell lines, and nearly all of the epithelial cell lines that are susceptible to wild-type EBV infection could also be successfully infected with the viral mutant in vitro, although the efficiency of infection with BLLF1-negative virus was clearly lower than the one observed with wild-type EBV. Our studies show that the interaction between BLLF1 and CD21 is not absolutely required for the infection of lymphocytes and epithelial cells, indicating that viral molecules other than BLLF1 can mediate the binding of EBV to its target cells. In this context, our results further suggest the hypothesis that additional cellular molecules, apart from CD21, allow virus entry into these cells.     

Quantitative assessment of whole-body tumor burden in adult patients with neurofibromatosis

Purpose

Patients with neurofibromatosis 1 (NF1), NF2, and schwannomatosis are at risk for multiple nerve sheath tumors and premature mortality. Traditional magnetic resonance imaging (MRI) has limited ability to assess disease burden accurately. The aim of this study was to establish an international cohort of patients with quantified whole-body internal tumor burden and to correlate tumor burden with clinical features of disease.

Methods

We determined the number, volume, and distribution of internal nerve sheath tumors in patients using whole-body MRI (WBMRI) and three-dimensional computerized volumetry. We quantified the distribution of tumor volume across body regions and used unsupervised cluster analysis to group patients based on tumor distribution. We correlated the presence and volume of internal tumors with disease-related and demographic factors.

Results

WBMRI identified 1286 tumors in 145/247 patients (59%). Schwannomatosis patients had the highest prevalence of tumors (P = 0.03), but NF1 patients had the highest median tumor volume (P = 0.02). Tumor volume was unevenly distributed across body regions with overrepresentation of the head/neck and pelvis. Risk factors for internal nerve sheath tumors included decreasing numbers of café-au-lait macules in NF1 patients (P = 0.003) and history of skeletal abnormalities in NF2 patients (P = 0.09). Risk factors for higher tumor volume included female gender (P = 0.05) and increasing subcutaneous neurofibromas (P = 0.03) in NF1 patients, absence of cutaneous schwannomas in NF2 patients (P = 0.06), and increasing age in schwannomatosis patients (p = 0.10).

Conclusion

WBMRI provides a comprehensive phenotype of neurofibromatosis patients, identifies distinct anatomic subgroups, and provides the basis for investigating molecular biomarkers that correlate with unique disease manifestations.     

A missense mutation in the NF2 gene results in moderate and mild clinical phenotypes of neurofibromatosis type 2

Since the identification of the NF2 tumor suppressor gene in 1993, various mutations have been found in NF2-related tumors and in lymphocytes from NF2 patients. Most of the reported mutations result in truncated gene products. Missense mutations affecting the tumor suppressor are rare. These missense mutations would provide valuable information for the understanding of the function of the tumor suppressor, since they should affect critical parts of the protein. In this study we describe a novel point mutation in exon 15 of the NF2 gene, which is found in lymphocyte DNA of two NF2 patients from one family. This mutation is expected to result in a substitution of Pro for Gln at codon 538. Though both of the two patients developed bilateral vestibular schwannomas, the first patient showed onset of the disease at the age of 31 years and presented with various central, peripheral and abdominal tumors, while the second patient showed later onset of clinical symptoms (at age 52 years) and presented with only two additional small spinal tumors.     

Virus and Autoantigen-Specific CD4+ T Cells Are Key Effectors in a SCID Mouse Model of EBV-Associated Post-Transplant Lymphoproliferative Disorders

Polyclonal Epstein-Barr virus (EBV)-infected B cell line (lymphoblastoid cell lines; LCL)-stimulated T-cell preparations have been successfully used to treat EBV-positive post-transplant lymphoproliferative disorders (PTLD) in transplant recipients, but function and specificity of the CD4+ component are still poorly defined. Here, we assessed the tumor-protective potential of different CD4+ T-cell specificities in a PTLD-SCID mouse model. Injection of different virus-specific CD4+ T-cell clones showed that single specificities were capable of prolonging mouse survival and that the degree of tumor protection directly correlated with recognition of target cells in vitro. Surprisingly, some CD4+ T-cell clones promoted tumor development, suggesting that besides antigen recognition, still elusive functional differences exist among virus-specific T cells. Of several EBV-specific CD4+ T-cell clones tested, those directed against virion antigens proved most tumor-protective. However, enriching these specificities in LCL-stimulated preparations conferred no additional survival benefit. Instead, CD4+ T cells specific for unknown, probably self-antigens were identified as principal antitumoral effectors in LCL-stimulated T-cell lines. These results indicate that virion and still unidentified cellular antigens are crucial targets of the CD4+ T-cell response in this preclinical PTLD-model and that enriching the corresponding T-cell specificities in therapeutic preparations may enhance their clinical efficacy. Moreover, the expression in several EBV-negative B-cell lymphoma cell lines implies that these putative autoantigen(s) might also qualify as targets for T-cell-based immunotherapy of virus-negative B cell malignancies.     

Introgression of Alectoris chukar genes into a Spanish wild Alectoris rufa population

In order to detect introgression of other Alectoris genus species into wild populations of Spanish Alectoris rufa, we studied a sample of 93 red-legged partridges (supposed to be A. rufa) captured in the island of Majorca. A set of 31 chukar partridges (Alectoris chukar) from Cyprus and 33 red-legged partridges (A. rufa) from one Spanish farm were also studied to provide suitable populations for comparison. Factorial correspondence analysis on microsatellite genotypes supported a clear distinction of birds from Cyprus, whereas partridges from Majorca and the Spanish farm overlapped in a wide area. The existence of A. chukar mitochondrial DNA in 16 individuals from Majorca indicated introgression into their maternal lineage even if their phenotypes were not different from A. rufa. Bayesian inference based on microsatellite analysis indicated a noticeable degree of genetic proximity to A. chukar only for one of these hybrids.     

Choline acetyltransferase.

Acetylcholine is essential to neural function. It synthesis is catalyzed by choline acetyltransferase, the enzyme responsible for the acetylation of choline by acetyl coenzye A, a reaction favored slightly thermodymodynamically and not at all kinetically. An analytically pure enzyme still has not been obtained; however, method of purification have been greatly improved recently. Numerous inhibitors of the enzyme have been synthesized and their structure-action relationships examained. Evidence has been accumulated showing the essential involvement of an imidazole group in the active site of choline acetyltransferase. The literature regarding the controversial role to thiol groups in choline acetyltransferase is reviewed. Recently, derivatives of coenzyme A have been introduced as inhibitors of this enzyme and the specificity of coenzyme A binding has been examined. Possible mechanisms responsible for the control fo acetylcholine synthesis are discussed.     

The complete DNA sequence and genomic organization of the avian adenovirus CELO.

The complete DNA sequence of the avian adenovirus chicken embryo lethal orphan (CELO) virus (FAV-1) is reported here. The genome was found to be 43,804 bp in length, approximately 8 kb longer than those of the human subgenus C adenoviruses (Ad2 and Ad5). This length is supported by pulsed-field gel electrophoresis analysis of genomes isolated from several related FAV-1 isolates (Indiana C and OTE). The genes for major viral structural proteins (Illa, penton base, hexon, pVI, and pVIII), as well as the 52,000-molecular-weight (52K) and 100K proteins and the early-region 2 genes and IVa2, are present in the expected locations in the genome. CELO virus encodes two fiber proteins and a different set of the DNA-packaging core proteins, which may be important in condensing the longer CELO virus genome. No pV or pIX genes are present. Most surprisingly, CELO virus possesses no identifiable E1, E3, and E4 regions. There is 5 kb at the left end of the CELO virus genome and 15 kb at the right end with no homology to Ad2. The sequences are rich in open reading frames, and it is likely that these encode functions that replace the missing El, E3, and E4 functions.     

Antigenic determinants of adenovirus capsids. II. Homogeneity of hexons, and accessibility of their determinants, in the virion.

We have tested the two principal theories which explain the previous finding that small amounts of type-specific antibody to the adenovirus hexon can neutralize infectivity, whereas even large amounts of cross-reactive antibody do not. a) It has been suggested that the type-specific determinants are especially prominent in the virion. We have therefore measured the capacity of whole virus to bind appropriate antibodies, using a sensitive radioimmunoprecipitation (RIP) system. In fact, virions bound type-specific and cross-reactive antibodies impartially. Moreover, they bound both much less effectively than did free hexon or disrupted virus, suggesting that many of each kind of determinant are inaccessible in virions. b) It has been suggested that the type-specific determinants are confined to those hexons located next to the pentons, and that they are the targets for neutralizing antibody. We have therefore studied the antigenicity of peripentonal and nonamer hexons isolated from virions, and found that each possessed both kinds of determinants. Furthermore, these were present in the same proportion as in hexons purified from the soluble antigens in infected cells ("free hexons"). We concluded that the mechanism of neutralization by antibody is complicated, and that the type-specific determinants exposed on the virion must play a crucial role.     

High frequency of mosaicism among patients with neurofibromatosis type 1 (NF1) with microdeletions caused by somatic recombination of the JJAZ1 gene

Detailed analyses of 20 patients with sporadic neurofibromatosis type 1 (NF1) microdeletions revealed an unexpected high frequency of somatic mosaicism (8/20 [40%]). This proportion of mosaic deletions is much higher than previously anticipated. Of these deletions, 16 were identified by a screen of unselected patients with NF1. None of the eight patients with mosaic deletions exhibited the mental retardation and facial dysmorphism usually associated with NF1 microdeletions. Our study demonstrates the importance of a general screening for NF1 deletions, regardless of a special phenotype, because of a high estimated number of otherwise undetected mosaic NF1 microdeletions. In patients with mosaicism, the proportion of cells with the deletion was 91%-100% in peripheral leukocytes but was much lower (51%-80%) in buccal smears or peripheral skin fibroblasts. Therefore, the analysis of other tissues than blood is recommended, to exclude mosaicism with normal cells in patients with NF1 microdeletions. Furthermore, our study reveals breakpoint heterogeneity. The classic 1.4-Mb deletion was found in 13 patients. These type I deletions encompass 14 genes and have breakpoints in the NF1 low-copy repeats. However, we identified a second major type of NF1 microdeletion, which spans 1.2 Mb and affects 13 genes. This type II deletion was found in 8 (38%) of 21 patients and is mediated by recombination between the JJAZ1 gene and its pseudogene. The JJAZ1 gene, which is completely deleted in patients with type I NF1 microdeletions and is disrupted in deletions of type II, is highly expressed in brain structures associated with learning and memory. Thus, its haploinsufficiency might contribute to mental impairment in patients with constitutional NF1 microdeletions. Conspicuously, seven of the eight mosaic deletions are of type II, whereas only one was a classic type I deletion. Therefore, the JJAZ1 gene is a preferred target of strand exchange during mitotic nonallelic homologous recombination. Although type I NF1 microdeletions occur by interchromosomal recombination during meiosis, our findings imply that type II deletions are mediated by intrachromosomal recombination during mitosis. Thus, NF1 microdeletions acquired during mitotic cell divisions differ from those occurring in meiosis and are caused by different mechanisms.