Molecular alterations in pediatric brainstem gliomas

1 Background

Diffuse intrinsic pontine gliomas (DIPGs) have a dismal prognosis. Previously, diagnosis was based on a typical clinical presentation and magnetic resonance imaging findings. After the start of the era of biopsies, DIPGs bearing H3 K27 mutations have been reclassified into a novel entity, diffuse midline glioma, based on the presence of this molecular alteration. However, it is not well established how clinically diagnosed DIPG overlap with H3 K27‐mutated diffuse midline gliomas, and whether rare long‐term survivors also belong to this group.

2 Methods

We studied tumor samples obtained at diagnosis or upon autopsy from 23 children, including two long‐term survivors. Based on clinical, radiological, and histological findings, all tumors were previously diagnosed as DIPGs. All samples were analyzed for genetic alterations by next‐generation sequencing (NGS) and for protein expression by immunohistochemistry (IHC).

3 Results

H3 K27 was mutated in NGS or IHC in 20 patients, excluding both long‐term survivors. One of these long‐term survivors harbored a mutation in IDH1, formerly considered to be an alteration absent in pediatric diffuse brainstem gliomas. Other altered genes in NGS included TP53 (10 patients), MET and PDGFRA (3 patients each), VEGFR and SMARCA4 (2 patients each), and PPARγ, PTEN and EGFR in 1 patient, respectively. IHC revealed cMYC expression in 15 of 24 (63%) of all samples, exclusively in the biopsies.

4 Conclusions

Eighty‐seven percent of the tumors formerly diagnosed as DIPGs could be reclassified as H3 K27‐mutated diffuse midline gliomas. Both long‐term survivors lacked this alteration. Contrary to former conceptions, IDH1 mutations may occur also in pediatric brainstem gliomas.     

Precurarisation in infants and children less than three years of age

Sixty patients less than three years of age about to undergo adenoidectomy or endoscopy were divided into three groups of 20 each according to age (0-11 months, 12-23 months, 24-35 months). Before the induction of anaesthesia with thiopentone, either tubocurarine 0.05 mg X kg-1 or normal saline was given at random in a double-blind fashion. Three minutes later, the children received succinylcholine 1.5 or 1.0 mg X kg-1, respectively. Muscle movements were graded according to a four-point scale. Blood was sampled for creatine kinase (CK) activity before anaesthesia and on the following morning. When all age groups were combined, there was a significant reduction of muscle movements in patients who had received tubocurarine pretreatment. Serum CK activity rose significantly when saline pretreatment was used in children over the age of one year but not in the infants, despite the presence of muscle movements following succinylcholine administration.     

Associations between number of different type of care meetings with social network and improvement in mental well-being in adolescents at risk of first-episode psychosis

Aim: As research in the care of people at risk of developing first‐episode psychosis has mostly focused on cognitive behavioural therapy and antipsychotic medication, little is known about associations between changes in mental well‐being and effect of people participating in the care. Methods: Multiprofessional early intervention team met with adolescents who are at risk of psychosis, including coworkers and their families. Correlations were calculated between change scores in prepsychotic, functioning ability, quality of life (QoL), depression and anxiety scales, and number of family, coworker and adolescent‐participating social network meetings, and total number of social network meetings during the care. Results: Larger change scores in functioning ability were positively associated with the number of social network meetings with participating coworker (P = 0.041), but not with other types of participant meetings. Larger change scores in prepsychotic symptoms were positively associated with the number of meetings where the adolescent was participating (P = 0.001), the number of network meetings where the coworker was participating (P = 0.007) and the number of all meetings (P = 0.001). The number of any other type of meetings did not associate with change scores in QoL, depression and anxiety. Conclusion: According to the present results, adolescents at risk of psychosis seem to benefit from the inclusion of coworkers from the adolescents' natural surroundings in care; this could help to increase functioning ability. Different combinations of meetings, such as larger number of total meetings, larger number of meetings with the adolescent and larger number of meetings with coworkers from the adolescents' natural surroundings, seem to associate with stronger decrease in pre‐psychotic symptoms.     

Identification of a histidine-tyrosine cross-link in the active site of the cbb3-type cytochrome c oxidase from Rhodobacter sphaeroides

The heme-copper oxidases constitute a superfamily of terminal dioxygen-reducing enzymes located in the inner mitochondrial or in the bacterial cell membrane. The presence of a mechanistically important covalent bond between a histidine ligand of the copper ion (Cu(B)) in the active site and a generally conserved tyrosine residue nearby has been shown to exist in the canonical cytochrome c oxidases. However, according to sequence alignment studies, this critical tyrosine is missing from the subfamily of cbb(3)-type oxidases found in certain bacteria. Recently, homology modeling has suggested that a tyrosine residue located in a different helix might fulfill this role in these enzymes. Here, we show directly by methods of protein chemistry and mass spectrometry that there is indeed a covalent link between this tyrosine and the copper-ligating histidine. The identity of the cross-linked tyrosine was determined by showing that the cross-link is not formed when this residue is replaced by phenylalanine, even though structural integrity is maintained. These results suggest a universal functional importance of the histidine-tyrosine cross-link in the mechanism of O(2) reduction by all heme-copper oxidases.     

Matrix metalloproteinase-13 (MMP-13, collagenase-3) is highly expressed in human tooth pulp

Matrix metalloproteinases (MMPs) and their specific tissue inhibitors (TIMPs) participate into extracellular matrix degradation in physiological and pathological conditions. We hypothesized that MMP expression in pulp tissue changes in response to caries attack and investigated the gene expression profiles of MMPs and TIMPs in pulp tissue of sound and carious teeth with cDNA microarray. cDNA microarray demonstrated an extremely high MMP-13 (collagenase-3) mRNA expression in pooled pulp samples of sound and carious teeth, with less pronounced expression of MMP-16 (MT3-MMP) and TIMP-1. Real-time quantitative polymerase chain reaction of individual pulp samples revealed a wide range of the MMP-13 expression level between pulp samples with possible downregulation of MMP-13 expression during caries progression. Western blot and immunohistochemical staining confirmed the presence of MMP-13 with no observable differences between sound and carious teeth pulp tissues. The results reveal that MMP-13 is expressed and synthesized in pulp tissue, an interesting feature considering the very limited expression of MMP-13 in normal adult tissues. Further studies with a larger sample size are needed to clarify the changes in MMP-13 expression during caries progression.