Mosaic tetraploidy in a two-year-old female

A 24-month-old female with severe physical and mental retardation is described. Peripheral lymphocytes demonstrated tetraploid/diploid mosaicism. That this does not represent an artifact in vitro was supported by the finding of buccal mucosal cells with two Barr bodies and tetraploid/diploid mosaicism in fibroblasts and bone marrow cells.     

Apolipoprotein D is down-regulated during malignant transformation of neurofibromas

Apolipoprotein D (apoD) expression was studied in nonneoplastic peripheral nerve, neurofibromas (NFs), and malignant peripheral nerve sheath tumors (MPNSTs) by quantitative polymerase chain reaction, in situ hybridization, and immunohistochemistry. Multiplex quantitative polymerase chain reaction for messenger RNA was performed on a series of formalin-fixed and paraffin-embedded specimens that included 9 MPNSTs, 12 NFs, and 4 normal peripheral nerves. The average apoD expression was 108-fold decreased (DeltaCt = -7.3) in the MPNSTs compared with the NFs (P < .05). ApoD expression levels were 3.0-fold elevated (DeltaCt = 1.7) in the NFs compared with nonneoplastic peripheral nerve (P < .05). In situ hybridization for apoD RNA was performed on a separate series of 10 cases in which each microscopic section included both MPNST and the NF from which it arose. These studies confirmed elevated apoD expression in NFs compared with MPNSTs and demonstrated that this expression was variable among individual cells within the NFs. Differential expression by immunohistochemistry could only be demonstrated in selected areas, most likely because apoD protein is a small molecule that is secreted out of the cell into the extracellular space and plasma. ApoD expression initially increases a small amount with the formation of NFs from nonneoplastic peripheral nerve and subsequently decreases markedly as NFs transform into MPNSTs. This expression pattern may serve as a marker for cell cycle inhibition during peripheral nerve tumorigenesis.     

Purine nucleoside phosphorylase deficiency: a new case report and identification of two novel mutations (Gly156A1a and Val217Ile), only one of which (Gly156A1a) is deleterious

Purine nucleoside phosphorylase (PNP) deficiency results in an autosomal recessive immunodeficiency disease characterized by initial involvement of cellular immunity and neurological manifestations with subsequent abnormalities of humoral immunity. The initial presentation and clinical course has varied widely in the relatively few published cases. The molecular basis has been reported in only 10 patients, precluding evaluation of phenotype-genotype relationships. We now report clinical, immunologic, and molecular findings in a new case of relatively early onset that emphasizes hypotonia and developmental delay as early manifestations. The patient carried two novel missense mutations (Gly56A1a and Val217Ile) on the same allele in apparent homozygosity. Expression of each of the mutant enzymes in vitro demonstrated that the Gly156A1a mutation abolished enzyme activity while the Val217Ile mutation was without obvious effect and is therefore a normal variant. Such "normal" polymorphisms might be associated with a variable response to the immunosuppressive PNP inhibitors currently in clinical trials.     

The development of synaptic plasticity induction rules and the requirement for postsynaptic spikes in rat hippocampal CA1 pyramidal neurones

Coincident pre- and postsynaptic activity induces synaptic plasticity at the Schaffer collateral synapse onto CA1 pyramidal neurones. The precise timing, frequency and number of coincident action potentials required to induce synaptic plasticity is currently unknown. In this study we show that the postsynaptic activity required for the induction of long-term potentiation (LTP) changes with development. In acute slices from adult rats, coincident pre- and postsynaptic theta burst stimulation (TBS) induced LTP and we show that multiple high-frequency postsynaptic spikes are required. In contrast, in acute slices from juvenile (P14) rats, TBS failed to induce LTP unless the excitatory postsynaptic potentials (EPSPs) were of sufficient magnitude to initiate action potentials. We also show that coincident individual pre- and postsynaptic action potentials are only capable of inducing LTP in the juvenile when given at a frequency greater than 5 Hz and that the timing of individual pre- and postsynaptic action potentials relative to one another is not important. Finally, we show that local tetrodotoxin (TTX) application to the soma blocked LTP in adults, but not juveniles. These data demonstrate that somatic spiking is more important for LTP induction in the adult as opposed to juvenile rats and we hypothesize that the basis for this is the ability of action potentials in the postsynaptic CA1 pyramidal neurone to back-propagate into the dendrites. Therefore, the pre- and postsynaptic activity patterns required to induce LTP mature as the hippocampus develops.     

Copolymer effects on microglia and T cells in the central nervous system of humanized mice

The random amino acid copolymers FYAK and VWAK ameliorate EAE in a humanized mouse model expressing both a human transgenic myelin basic protein (MBP)85-99-specific T cell receptor and HLA-DR2. Here we show that microglia isolated from the central nervous system (CNS) of humanized mice with EAE induced by MBP85-99 and treated with these copolymers had reduced expression of HLA-DR, and thus reduced capacity to present MBP85-99 and activate transgenic T cells. In vitro microglia up-regulated empty HLA-DR2 upon activation with GM-CSF with or without LPS or IFN-gamma, but not with IL-4 or IL-10. Correspondingly, gene chip arrays showed that the CNS of untreated and YFAK-treated mice differentially expressed pro- and anti-inflammatory molecules during MBP85-99-induced EAE. Interestingly, microglia expressed the full-length gammabeta and alphabeta subunits of the tetrameric adaptor protein complexes AP-1 and AP-2 respectively, but after treatment with GM-CSF these complexes were cleaved, as had been found in immature dendritic cells derived from bone marrow. Strikingly, in vivo the perivascular lymphocyte infiltration seen in untreated mice immunized with MBP85-99 was composed of equal numbers of hVbeta2+ MPB85-99-specific transgenic and hVbeta2- endogenous T cells, while the much smaller infiltration seen after treatment with YFAK was composed predominantly of hVbeta2- endogenous T cells.     

Rubinstein-Taybi syndrome medical guidelines

Children and adults with Rubinstein-Taybi Syndrome have specific medical conditions that occur with greater frequency than the general population. Based on the available information from the literature and clinical experience, recommendations for specific surveillance and interventions are made to guide those clinicians caring for individuals with Rubinstein-Taybi Syndrome. This is a first attempt at medical guidelines for individuals with RTS in the United States. On-going research is needed in many areas to guide decisions in medical care and allow for refinement of these medical guidelines.     

Modeling of longitudinal academic achievement scores after pediatric traumatic brain injury

In a prospective longitudinal study, academic achievement scores were obtained from youth 5 to 15 years of age who sustained mild-moderate (n = 34) or severe (n = 43) traumatic brain injuries (TBI). Achievement scores were collected from baseline to 5 years following TBI and were subjected to individual growth curve analysis. The models fitted age at injury, years since injury, duration of impaired consciousness, and interaction effects to Reading Decoding, Reading Comprehension, Spelling, and Arithmetic standard scores. Although scores improved significantly over the follow-up relative to normative data from the standardization sample of the tests, children with severe TBI showed persistent deficits on all achievement scores in comparison to children with mild-moderate TBI. Interactions of the slope and age parameters for the Arithmetic and Reading Decoding scores indicated greater increases over time in achievement scores of the children injured at an older age, but deceleration in growth curves for the younger children with both mild-moderate and severe TBI. These results are compatible with the hypothesis that early brain injuries disrupt the acquisition of some academic skills. Hierarchical regression models revealed that indexes of academic achievement obtained 2 years following TBI had weak relations with the duration of impaired consciousness and socioeconomic status. In contrast, concurrent cognitive variables such as phonological processing and verbal memory accounted for more variability in academic scores. Given the significant and persistent decrement in basic academic skills in youth with severe TBI, it is clear that head-injured youth require intensive, long-term remediation and intervention not only of the academic skills themselves, but also of those cognitive abilities that support the development and maintenance of reading and math.     

Chitinases and chitinase-like proteins in T(H)2 inflammation and asthma

Chitin is the second most abundant biopolymer in nature, where it protects crustaceans, parasites, fungi, and other pathogens from the adverse effects of their environments, hosts, or both. Because chitin does not exist in mammals, it had been assumed that the chitinases that degrade it are also restricted to lower life forms. However, chitinases and chitinase-like proteins have recently been noted in mice and human subjects. The prototypic chitinase, acidic mammalian chitinase, was also noted to be induced during T(H)2 inflammation through an IL-13-dependent mechanism. It was also shown to play an important role in the pathogenesis of T(H)2 inflammation and IL-13 effector pathway activation and demonstrated to be expressed in an exaggerated fashion in human asthmatic tissues. The finding that chitinases contribute to host anti-parasite responses and asthmatic T(H)2 inflammation support the concept that asthma might be a parasite-independent anti-parasite response.     

Langerhans cell histiocytosis immunohistochemical expression of fascin,a dendritic cell marker

Langerhans cell histiocytosis (LCH) is a clonal disorder believed to be derivedfrom cells of the dendritic system. Fascin, a 55-kd actin-bundling protein, represents a highly selective marker for dendritic cells of lymphoid tissues and peripheral blood and is involved in the formation of dendritic processes in maturing epidermal Langerhans cells. Since lesional cells of LCH may represent Langerhans cells arrested at an early stage of activation, immunohistochemical expression offascin in epidermal Langerhans cells and in the lesional cells of 34 cases of LCH was evaluated in paraffin sections using an immunoalkaline phosphatase technique. Though epidermal Langerhans cells were nonreactive for fascin, lesional cells in all LCH cases exhibited immunoreactivityforfascin, CD1a, and S-100 protein. Variation in staining intensity was observed in some cases, possibly reflecting differences in cell maturation or activation. Involved tissues included bone, soft tissue, lymph node, thyroid, orbit, and extradural cranial tissue. Immunoreactivity of lesional cells of LCH for fascin supports their derivation from cells of the dendritic system and represents another alteration in the phenotype of Langerhans cells that is associated with maturation, migration, culture, or clonal expansion.