Surgical treatment of paediatric malignant neuroepithelial brain tumors

The role of the neurosurgeon in dealing with malignant neuroepithelial brain tumors, both supra- and infratentorial, in paediatric age, is stressed; this because surgery is the main therapy, and also it is mandatory, in order to achieve the pathological diagnosis, essential for planning any kind of complementary treatment. Open surgery versus stereotactic biopsy is considered, with emphasis on brain stem tumors. The treatment of malignant tumor recurrencies is also discussed, and the indications of a second surgical look in patients harboring recurrent medulloblastoma is proposed for discussion, when long disease-free time occur and combined modality treatments are performed.     

T CELL RECEPTOR DELTA LOCUS POLYMORPHISM IN RHEUMATOID ARTHRITIS

In order to identify new susceptibility markers for Rheumatoid Arthritis (RA), we analysed the dinucleotide repeat polymorphism at the T cell receptor delta locus (TCRD) in 65 RA patients and 99 healthy Belgian controls. A significant under-representation of the A4-A5 TCRD genotype was observed in the RA population.     

The potential role of lonidamine (LND) in the treatment of malignant glioma

Summary Up-to-date unsatisfactory results obtained in multimodality treatments of malignant glioma have prompted the research of new therapeutic modalities with unconventional modes of action. Lonidamine (LND) is a drug which reduces aerobic glycolytic activity in both human and experimental tumors. This effect mainly depends on the inhibition of mitochondrially-bound hexokinase (HK) which is present in large amounts in malignant cells. A Phase II study was conducted on patients with recurrent glioma; 12 patients were admitted to the study. Clinical side effects were moderate, necessitating a reduction of the dosage in only 1 case. The objective results were evaluated according to the indications of Levin. 2 responders and 3 cases of stable disease were observed out of 10 evaluable patients. The potential value of this new drug is discussed.     

T-cell vaccination in multiple sclerosis: update on clinical application and mode of action

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Autoreactive T cells specific for myelin antigens are considered to play a prominent role in the initiation of the local inflammatory response, ultimately leading to myelin damage. Several studies indicate that autoreactive T cells are not completely deleted in the thymus, but are part of the normal T cell repertoire. Accidentally activated autoreactive T cells, however, may not automatically lead to autoimmune disease. Several reports support the existence of peripheral regulatory networks that prevent the activation and expansion of pathogenic T cells. Anti-idiotypic and anti-ergotypic T cells are part of this regulatory network and are thought to control autoreactive T cells by recognition of certain clonotypic and ergotypic determinants. These clonotypic networks may not function properly in patients with MS. Immunization with attenuated autoreactive T cells, termed T cell vaccination (TCV), may enhance or restore the regulatory networks to specifically suppress the autoreactive T cells as shown in experimental autoimmune encephalomyelitis (EAE), a commonly used animal model for MS. In the past decade, TCV has been tested for MS in several clinical trails. This review summarizes these clinical trails and updates our current knowledge on the mode of action of T cell vaccination.     

Segmental duplications and gene conversion: Human luteinizing hormone/chorionic gonadotropin beta gene cluster

Segmental duplicons (>1 kb) of high sequence similarity (>90%) covering >5% of the human genome are characterized by complex sequence variation. Apart from a few well-characterized regions (MHC, β-globin), the diversity and linkage disequilibrium (LD) patterns of duplicons and the role of gene conversion in shaping them have been poorly studied. To shed light on these issues, we have re-sequenced the human Luteinizing Hormone/Chorionic Gonadotropin β (LHB/CGB) cluster (19q13.32) of three population samples (Estonians, Mandenka, and Han). The LHB/CGB cluster consists of seven duplicated genes critical in human reproduction. In the LHB/CGB region, high sequence diversity, concentration of gene-conversion acceptor sites, and strong LD colocalize with peripheral genes, whereas central loci are characterized by lower variation, gene-conversion donor activity, and breakdown of LD between close markers. The data highlight an important role of gene conversion in spreading polymorphisms among duplicon copies and generating LD around them. The directionality of gene-conversion events seems to be determined by the localization of a predicted recombination “hotspot” and “warm spot” in the vicinity of the most active acceptor genes at the periphery of the cluster. The data suggest that enriched crossover activity in direct and inverted segmental repeats is in accordance with the formation of palindromic secondary structures promoting double-strand breaks rather than fixed DNA sequence motifs. Also, this first detailed coverage of sequence diversity and structure of the LHB/CGB gene cluster will pave the way for studying the identified polymorphisms as well as potential genomic rearrangements in association with an individual's reproductive success.     

Clonal expansion of myelin basic protein-reactive T cells in patients with multiple sclerosis: Restricted T cell receptor V gene rearrangements and CDR3 sequence

Myelin basic protein (MBP)-reactive T cells are thought to play an important role in the pathogenesis of multiple sclerosis (MS). In some patients with MS, these autoreactive T cells display a limited heterogeneity in their epitope recognition and T cell receptor (TCR) variable (V) gene usage. These individual-dependent properties of MBP-reactive T cells have led to the speculation that they may represent clonal expansion in vivo in some MS patients. In the present study, 51 MBP-reactive T cell clones derived from patients with MS and healthy individuals were examined for their epitope recognition and the TCR Vα and Vβ gene rearrangements. The V gene junctional region sequences of identified α and β genes were further analyzed to probe their clonal origins, as the sequences are unique for individual clones. Our data showed that 26 clones derived from nine patients with MS shared a predominant reactivity to the immunodominant regions of MBP, 84–102, 110–129 and 143–168, and used various TCR Vα and Vβ rearrangements. The V gene usage of the clones was restricted to certain Vα Vβ combination(s) in a given MS patient, but varied among different patients. The sequence analysis revealed that the clones generated from a given patient shared a limited or a single junctional region sequence pattern(s), indicating their oligoclonal or monoclonal origin(s). In contrast, 25 MBP-reactive T cell clones derived from normal individuals exhibited unfocused epitope recognition and V gene usage. Thus, the limited heterogeneity of MBP-reactive T cells in their structural and functional charactertistics reflects their clonal expansion in vivo in some patients with MS.     

Whole-exome sequencing of Finnish patients with vascular cognitive impairment

Cerebral small vessel disease (CSVD) is the most important cause of vascular cognitive impairment (VCI). Most CSVD cases are sporadic but familial monogenic forms of the disorder have also been described. Despite the variants identified, many CSVD cases remain unexplained genetically. We used whole-exome sequencing in an attempt to identify novel gene variants underlying CSVD. A cohort of 35 Finnish patients with suspected CSVD was analyzed. Patients were screened negative for the most common variants affecting function in NOTCH3 in Finland (p.Arg133Cys and p.Arg182Cys). Whole-exome sequencing was performed to search for a genetic cause of CSVD. Our study resulted in the detection of possibly pathogenic variants or variants of unknown significance in genes known to associate with CSVD in six patients, accounting for 17% of cases. Those genes included NOTCH3, HTRA1, COL4A1, and COL4A2. We also identified variants with predicted pathogenic effect in genes associated with other neurological or stroke-related conditions in seven patients, accounting for 20% of cases. This study supports pathogenic roles of variants in COL4A1, COL4A2, and HTRA1 in CSVD and VCI. Our results also suggest that vascular pathogenic mechanisms are linked to neurodegenerative conditions and provide novel insights into the molecular basis of VCI.Subject terms: Stroke, Sequencing, Genetics research, Dementia     

Comparison of the affinities to bovine and human prothrombin of the staphylocoagulases from Staphylococcus intermedius and Staphylococcus aureus of animal origin.

Staphylocoagulases of Staphylococcus aureus (40 strains originally isolated from horses, dogs, cats, cows, sheep, opossums, pigs, humans, and a goat) and Staphylococcus intermedius (19 isolates from dogs and 1 pigeon strain) were tested for their affinity to prothrombins of either bovine or human origin. The tests used were the coagulase tube test (using human, bovine, or equine fibrinogen with either bovine or human prothrombin as the source of coagulase-reacting factor) and a chromogenic assay which enabled quantification of the amidolytic activity of the staphylocoagulase-prothrombin complex. S. intermedius showed weak specificity for human prothrombin, with 15% of the coagulases clotting human fibrinogen, 25% clotting equine fibrinogen, and 40% clotting bovine fibrinogen. However, 65% of coagulases clotted equine fibrinogen, 75% of coagulases clotted human fibrinogen, and 100% of coagulases clotted bovine fibrinogen when bovine prothrombin was used. The animal isolates of S. aureus displayed more diverse specificity toward prothrombin than S. intermedius strains. While 85% of coagulase preparations clotted human fibrinogen when human prothrombin was used, only 45% of preparations clotted bovine fibrinogen when bovine prothrombin was used. However, 62.5% of coagulases clotted human fibrinogen when bovine prothrombin was used and 85% of coagulases clotted bovine fibrinogen when human prothrombin was used. This may be a reflection of the diversity of the animal origins of S. aureus isolates.