The burden of paediatric stroke and cerebrovascular disorders in Croatia.

Pediatric stroke is significantly less common than stroke in adults, but represents a major challenge to public health authorities. The aim of this retrospective study was to identify the total and annual number of children younger than 18 years with arterial ischaemic stroke and transient ischaemic attack referred to the Children's Hospital Zagreb, which is a major national centre specialised for the treatment and prevention of stroke in children. We reviewed the medical records of the Department of Neuropediatrics database at the Children's Hospital Zagreb between 1998-2005 in order to provide demographic and clinical characteristics and neuroimaging findings in children with arterial ischaemic stroke. In the 7-year period, we identified a total of 124 children from different geographic areas of Croatia with a confirmed diagnosis of transient ischaemic attack (N=77), and arterial ischaemic stroke (N=47). Perinatal and childhood arterial ischaemic stroke were equally represented (23 and 24 children, respectively). The average number of new cases identified each year was 18 cases (range: 12-21), seven arterial ischaemic stroke and 11 transient ischaemic attack cases. Male predominance was found in children with arterial ischaemic stroke with a male : female ratio of 1.76 : 1, and was slightly higher in childhood arterial ischaemic stroke compared with perinatal arterial ischaemic stroke (2 : 1 and 1.56 : 1, respectively). In contrast, transient ischaemic attack was more frequently found in girls, and more likely identified in older children compared with younger children with arterial ischaemic stroke. Obtained data will contribute to better understanding of paediatric stroke in Croatia and will provide a base for the establishment of the national referral center and national pediatric stroke registry.

Biased emotional attention in post-traumatic stress disorder: a help as well as a hindrance?

BACKGROUND: From a cognitive neuroscience perspective, the emotional attentional bias in post-traumatic stress disorder (PTSD) could be conceptualized either as emotional hyper-responsiveness or as reduced priming of task-relevant representations due to dysfunction in 'top-down' regulatory systems. We investigated these possibilities both with respect to threatening and positive stimuli among traumatized individuals with and without PTSD. METHOD: Twenty-two patients with PTSD, 21 trauma controls and 20 non-traumatized healthy participants were evaluated on two tasks. For one of these tasks, the affective Stroop task (aST), the emotional stimuli act as distracters and interfere with task performance. For the other, the emotional lexical decision task (eLDT), emotional information facilitates task performance. RESULTS: Compared to trauma controls and healthy participants, patients with PTSD showed increased interference for negative but not positive distracters on the aST and increased emotional facilitation for negative words on the eLDT. CONCLUSIONS: These findings document that hyper-responsiveness to threat but not to positive stimuli is specific for patients with PTSD.

The impact of processing load on emotion.

This event-related fMRI study examined the impact of processing load on the BOLD response to emotional expressions. Participants were presented with composite stimuli consisting of neutral and fearful faces upon which semi-transparent words were superimposed. This manipulation held stimulus-driven features constant across multiple levels of processing load. Participants made either (1) gender discriminations based on the face; (2) case judgments based on the words; or (3) syllable number judgments based on the words. A significant main effect for processing load was revealed in prefrontal cortex, parietal cortex, visual processing areas, and amygdala. Critically, enhanced activity in the amygdala and medial prefrontal cortex seen during gender discriminations was significantly reduced during the linguistic task conditions. A connectivity analysis conducted to investigate theories of cognitive modulation of emotion showed that activity in dorsolateral prefrontal cortex was inversely related to activity in the ventromedial prefrontal cortex. Together, the data suggest that the processing of task-irrelevant emotional information, like neutral information, is subject to the effects of processing load and is under top-down control.

The role of the amygdala and rostral anterior cingulate in encoding expected outcomes during learning.

Successful passive avoidance learning is thought to require the use of learned stimulus-reinforcement associations to guide decision making [Baxter, M.G., Murray, E.A., 2002. The amygdala and reward. Nature Reviews. Neuroscience 3, 563-573]. The current experiment investigated the neural correlates of successful passive avoidance learning in 19 healthy adults. Behaviorally, subjects showed a distinct pattern of performance: early indiscriminate responding to stimuli (pre-criterion performance), followed by relatively rapid learning before a plateau of successful performance (post-criterion performance). Neural responses to post-criterion correct responses were compared with neural responses to both incorrect responses and pre-criterion correct responses. Post-criterion correct responding was associated with increased activation in regions including rostral anterior cingulate, insula, caudate, hippocampal regions, and the amygdala.

Long-term potentiation in vivo increases rat hippocampal tenascin-C expression.

We investigated the expression of the extracellular matrix glycoprotein tenascin-C after induction of long-term potentiation (LTP) by high-frequency tetanization (HFT) in the rat dentate gyrus in vivo. Expression of tenascin-C was evaluated at the mRNA and protein levels by in situ hybridization and immunocytochemistry, respectively. Whereas no tenascin-C mRNA was detectable in control animals, an increase in tenascin-C mRNA levels was observed in the granule cell layer of the dentate gyrus 4 h after HFT. At 24 h after HFT, tenascin-C mRNA had returned to control levels. Expression of tenascin-C protein 4 h after HFT followed that of controls in that tenascin was detectable in the strata oriens and radiatum of CA1, in the molecular layer, and within a narrow area at the inner surface of the granule cell layer in the dentate gyrus. However, 24 h after HFT, additional patches of tenascin-C immunoreactivity were observed in the molecular layer of the dentate gyrus. No increase in tenascin mRNA or protein levels was detected in control animals that received no stimulation, low-frequency stimulation, or HFT in the presence of the N-methyl-D-aspartate receptor antagonist D(-)-2-amino-5-phosphonopentanoic acid or the metabotropic glutamate receptor antagonist (R,S)-alpha-methyl-4-carboxyphenylglycine. These observations implicate a role for tenascin-C in N-methyl-D-aspartate and metabotropic glutamate receptor-dependent changes accompanying induction and/or maintenance of LTP.

Kainic acid activates transient expression of tenascin-C in the adult rat hippocampus.

Kainic acid-induced limbic seizures enhance expression of tenascin-C (TN) in the hippocampus of adult rats. TN mRNA was detectable by in situ hybridization in many granule cells in the dentate gyrus 4.5 hr after kainic acid injection but not in saline-injected animals (controls) or in animals killed 2 or 24 hr after injection. Thirty days after kainic acid injection, TN mRNA was detectable only in pyramidal cells of CA3 and CA1. At the protein level, TN was detectable by immunocytochemistry in control animals in the strata oriens and lacunosum moleculare of CA1, in the molecular layer, and within a narrow area at the inner surface of the granule cell layer in the dentate gyrus. Twenty-four hours after kainic acid injection, TN immunoreactivity was enhanced in these areas and throughout the granule cell layer. Thirty days after kainic acid injection, TN immunoreactivity was downregulated in these areas, while it was prominent in the stratum oriens and in clusters of immunoreactivity in the stratum lucidum of CA3. Western blot analysis of the hippocampus showed a peak of TN expression 24 hr after kainic acid injection. These observations show that TN expression is upregulated in predominantly neuronal cells already by 4.5 hr after kainic acid injection, coincident with activation of granule cells and sprouting of axon terminals, whereas the remaining TN expression 30 days after injection relates to pyramidal cells in CA1 and CA3, coincident with an astroglial response, as marked by a strong expression of glial fibrillary acidic protein.

Cytogenetic, cytomorphologic, and immunologic analysis in 55 children with acute lymphoblastic leukemia.

This paper presents the results of cytogenetic analysis in 55 children with acute lymphatic leukemia (ALL). Acquired chromosome aberrations were identified in 35 (63.6%) children. Difference in frequency of clonal aberrations depending on age of patients was observed. Thus, acquired aberrations were detected in all three children up to 6 months of age, in 57.8% in the group from 1-10 years, and in six (85.7%) of seven children older than 10 years of age at diagnosis. The analysis revealed chromosome aberrations specific for ALL. Hyperdiploidy >50 was identified in 20% of children, and the association with CALLA+ early pre-B and L2-ALL was observed. del(6) and t(1;19) were identified in 7.3% and 5.5% of children, respectively. No association with a specific morphology or specific immunophenotype for both structural aberrations has been established. The association of structural aberrations involving regions 14q11-12 and T-cell ALL, however, has been observed, as an aberration was identified in two (3.6%) children, i.e., in 25% of our T-cell leukemias. Interstitial deletion of the long arm of chromosome 13, a rare chromosomal aberration in ALL, was identified in addition to del(9)(q31) in a 17-month-old girl with constitutional trisomy of chromosome 21 and B-cell ALL-L2. Interesting is the finding of hyperdiploidy with 52 chromosomes and structural aberrations of chromosome 1 in a 1-month-old girl with morphologically unclassified CALLA+ pre-T acute leukemia. To our knowledge this is the first case of hyperdiploidy >50 in a neonatal leukemia.

Embryonal rhabdomyosarcoma with 92,XXYY, +dmin and evidence of spontaneous cell fusion.

The results of a cytogenetic analysis in an embryonal rhabdomyosarcoma are presented. A tetraploid karyotype with double minute chromosomes (dmin) was identified using a direct method of tumor tissue treatment. In 5% of the examined cells, evidence of spontaneous cell fusion was observed.

Chromosomal analysis of two neuroblastomas.

We report the results of cytogenetic analysis in two children with neuroblastoma. The analysis was performed on slides obtained from a 24-hour bone marrow (BM) culture or by a direct method of the primary tumor tissue. The structural and numeric karyotype aberrations were established, including structural aberrations of chromosome 1. The finding of i(1q) and t(1;5)(p22;q13) is of interest because these chromosome aberrations are rare in this type of disease.

Cytogenetic analysis in ataxia telangiectasia with malignant lymphoma.

We present the results of cytogenetic analysis in a brother and sister with ataxia telangiectasia (AT), one of whom had malignant T-cell lymphoma. In both children, cytogenetic analysis of phytohemagglutinin (PHA)-stimulated lymphocytes showed chromosomal instability and inv(7) in 10% of the cells examined. The malignant lymphoma was analyzed cytogenetically on slides obtained from short-term culture of the lymph node cells; 64 cells were analyzed. A heterogeneous cell population was noted. Fourteen cells (21.9%) had a normal male karyotype; t(7;14)(p14;q12) and inv(7)(p14q35) were observed in 6.3% and 3.1% of metaphases. Owing to low frequency, these cells are probably a characteristic of the basic disease and have no features of malignant cells. Forty cells (62.5%) had a pseudodiploid karyotype 46,XY,dup(1)(p22p36),del(5)(q33),del(12)(p11), without cytogenetically evident aberrations of chromosomes 7 and 14. The results of these investigations suggest that the cells with rearrangements of chromosomes 1, 5, and 12 are malignant cells and did not originate by transformation of cells with inv(7) and t(7;14).

Cytogenetic analysis in children with acute nonlymphocytic leukemia.

In this work we present the results of cytogenetic analysis of the malignant cells in 27 children with acute nonlymphocytic leukemia (ANLL). The aim of our investigations was to determine the frequency and types of chromosome aberrations in our population of children with ANLL. Successful cytogenetic analysis was carried out in 24 (89%) patients. Aberrant karyotypes of malignant cells were established in 58% of the cases. The most frequent chromosomal abnormality was t(8;21), identified in 5 (20.8%) patients, i.e., 4 of 10 M2-ANLL. Aberration frequency of chromosome 11 was 16.6% and was identified in 3 of 8 M5-ANLL. Trisomy 8 and monosomy 7 were identified in one patient each with M3 and M2-ANLL, respectively. del(13), a rare chromosome aberration in hemoblastoses, was found in a child with M1,t(8;21) and the loss of chromosome Y. Translocation t(1;11;21) with a break in regions 1q23, 11q23, and 21q22, is unusual and was identified in a boy with M2-ANLL; it can be considered as a variant form of the t(8;21).

Heterochromatic variability in children with acute lymphoblastic leukemia.

An analysis of the C-segment variability of chromosomes 1, 9, and 16 was carried out in 38 children with ALL, and 90 control subjects. When studying location variants, no differences were found between group of patients and the normal controls. A larger quantity of structural heterochromatin was, however, observed on chromosomes 1, 9, and 16, and a higher frequency of homologous chromosomes heteromorphism in children with ALL when compared with the control group.

Direct cytogenetic analysis of primary neuroblastoma.

In this paper the results of cytogenetic analysis of a metastatic neuroblastoma from a 14-month-old boy are described. Direct cytogenetic analysis was performed on tumor pieces obtained from surgery prior to therapy. Consistent numerical and structural chromosome aberrations were identified. The modal chromosome number was 48, with 9.4% of the cell population being in the near-tetraploid range. In all karyotyped cells, the Y chromosome was missing and additions of chromosomes 7 and 14 were identified. Two rearranged #1 were observed: del(1)(p22 or p31) and t(1;18)(p22 or p31;q11-12), resulting in monosomy of the distal segment of the short arm and trisomy of the long arm. In two cells, single minutes were found; this chromosomal aberration has been previously described in a case of metastatic neuroblastoma.

Premature chromosome condensation in children with acute lymphocytic leukemia (L1) and malignant histiocytosis.

In this study we report the observation of premature chromosome condensation (PCC) in two children with acute lymphocytic leukemia L1 and one child with malignant histiocytosis. Cytogenetic analysis was performed on peripheral blood or bone marrow cells cultivated for 24 hours without mitogen. In all three reported cases the modal karyotype was normal, while 12.9%, 5.5%, and 5% of spreads with PCC was observed, respectively.

Selective modulation of antibody response and natural killer cell activity by purine nucleoside analogues.

Analogues that are poor substrates for adenosine deaminase or purine nucleoside phosphorylase may mimic immunodeficiencies associated with the enzyme deficiencies, and their activities may be directed toward selected lymphocyte subpopulations. Four analogues were studied for their effects on primary antibody response to either a T-dependent (sheep erythrocytes) or T-independent (trinitrophenyl-conjugated Escherichia coli lipopolysaccharide) antigen as well as effects on T-cytotoxic and natural killer cell activities in mice. The nucleosides were: an adenosine analogue, tubercidin; two deoxyadenosine analogues, 2-chloro, 2'-deoxyadenosine and 2-fluoroadenine arabinoside-5'-phosphate; and a deoxyguanosine analogue, 9-beta-D-arabinosylguanine. Drugs were given i.p. once daily for 3 consecutive days. Immune responses were determined in spleen cell suspensions 1 day after the last dose. Tubercidin inhibited both T-cytotoxic and natural killer cell activities at doses that did not reduce primary antibody response, whereas the reverse was true for 2-chloro, 2'-deoxyadenosine and 2-fluoroadenine arabinoside-5'-phosphate. At higher doses, T-cytotoxic lymphocytes appeared to be more sensitive than natural killer cells to the deoxyadenosine analogues. 9-beta-D-Arabinosylguanine did not selectively inhibit the immune responses at doses that clearly reduced the yield of spleen lymphocytes. Assuming the analogues mimic endogenous nucleosides, the results suggest that natural killer cells are more sensitive to adenosine than are those cells responsible for primary antibody response, whereas the reverse is true for deoxyadenosine.

Cytogenetic analysis of a child with malignant histiocytosis.

This report presents the results of cytogenetic analysis of a child with malignant histiocytosis. The analysis was carried out on slides obtained following short-term cultures of peripheral blood cells. The malignant cells had a deletion of the long arm of chromosome #7, 46,XX,del(7)(q22).

Heterochromatic segment length of Y chromosome in 55 boys with malignant diseases.

By investigating heterochromatic segment variability in a group of boys with malignant disease a significantly greater value of the Yc:F index in relation to the control subjects was established.

Marker chromosome 1q+ in acute lymphocytic leukemia.

This paper presents the results of a cytogenetic analysis on a patient with acute lymphocytic leukemia (ALL) type L2 according to the FAB classification. Of the metaphases examined, 69.3% belong to the aberrant clone of pseudodiploid karyotype. Marker chromosome 14q+ has been identified in all the cells of the clone. Duplication was found in 30% of the metaphases, and in 15% triplication of the proximal segment of the long arm of chromosome #1 (q11-q21). In one metaphase the long arm of chromosome #1 is made up of segment q11-q21 four times repeated. Aberrations of chromosome #1 support the idea that heterochromatic region may be related to the higher degree of the cell malignity.

Variability of chromosomes 1, 9, and 16 in children with malignant diseases.

Heterochromatic segments of chromosomes #1, #9, and #16 were analyzed in 38 children with malignant disease and 42 healthy persons. The analysis was carried out on C-banded metaphases obtained by peripheral blood culture. Using a quantitative method of analysis, an association was established between C-segment length of chromosome #9 and malignant disease in children. A disturbed quantitative relation of C-heterochromatin of chromosomes #1, #9, and #16 was also found in the group of children with malignant disease.