Persistent mitochondrial dysfunction and perinatal exposure to antiretroviral nucleoside analogues

BACKGROUND

Zidovudine is commonly administered during pregnancy to prevent mother-to-child HIV-1 transmission. We investigated mitochondrial toxic effects in children exposed to zidovudine in utero and after birth.

METHODS

We analysed observations of a trial of tolerance of combined zidovudine and lamivudine and preliminary results of a continuing retrospective analysis of clinical and biological symptoms of mitochondrial dysfunction in children born to HIV-1-infected women in France. Mitochondrial dysfunction was studied by spectrophotometry and polarography of respiratory-chain complexes in various tissues.

FINDINGS

Eight children had mitochondrial dysfunction. Five, of whom two died, presented with delayed neurological symptoms and three were symptom-free but had severe biological or neurological abnormalities. Four of these children had been exposed to combined zidovudine and lamivudine, and four to zidovudine alone. No child was infected with HIV-1. All children had abnormally low absolute or relative activities of respiratory-chain complexes I, IV, or both months or years after the end of antiretroviral treatment. No mutation currently associated with constitutional disease was detected in any patient.

INTERPRETATION

Our findings support the hypothesis of a link between mitochondrial dysfunction and the perinatal administration of prophylactic nucleoside analogues. Current recommendations for zidovudine monotherapy should however be maintained. Further assessment of the toxic effects of these drugs is required.

Establishment of human microglial cell lines after transfection of primary cultures of embryonic microglial cells with the SV40 large T antigen

Four continuous cell lines of human microglial cells were obtained by transfection of enriched cultures of human embryonic brain-derived macrophages with a plasmid encoding for the large T antigen of SV40. The transformed cells had the macrophagic characteristics of adherence and intra-cytoplasmic non-specific esterase activity. They could phagocytize zymosan particles but the phagocytic activity remained low. They expressed several macrophagic antigens but not the monocytic markers CD14, CD4, CD68/Ki-M6 and CD11c. The cells could be activated to express class II major histocompatibility complex antigens after interferon-gamma activation. Finally, interleukin-6 was produced spontaneously by the cells and this production was further increased after interleukin-1 alpha stimulation.

MECP2 mutations account for most cases of typical forms of Rett syndrome

Rett syndrome (RTT) is a severe progressive neurological disorder that affects almost exclusively females, with an estimated prevalence of approximately one in 10 000-15 000 female births. Most cases are sporadic, but several reports about familial recurrence support X-linked dominant inheritance with male lethality. The gene responsible for this disorder, MECP2, was recently identified by candidate gene strategy. Mutations were detected in <25% of RTT cases in this first report. To characterize the spectrum of mutations in the MECP2 gene in RTT patients, we selected 46 typical RTT patients and performed mutation screening by denaturing gradient gel electrophoresis combined with direct sequencing. We identified 30 mutations, accounting for 65% of RTT patients. They include 12 novel mutations (11 located in exon 3 and one in exon 2). Mutations, such as R270X and frameshift deletions in a (CCACC) (n) rich region, have been found with multiple recurrences. Most of the mutations were de novo, except in one family where the non-affected transmitter mother exhibited a bias of X inactivation. Although this study showed that MECP2 mutations account for most cases of typical forms of RTT (65%) and mutations in non-coding regions cannot be excluded for the remaining cases, an alternative hypothesis that takes into account the homogeneous phenotype and exclusive involvement of females, could be the implication in RTT of a putative second X-linked gene.

The neuropathogenesis of HIV-1 infection

HIV infection in brain revolves around productive viral replication in cells of mononuclear phagocyte lineage, including brain macrophages, microglia, and multinucleated giant cells [1-4]. Together, they are the investigators for cellular and viral neurotoxic activities [5-10]. Several published reports show that viral and/or cellular products produced from HIV-1-infected macrophages injure neurons and induce glial proliferation during advancing central nervous system (CNS) infection [11-18]. These findings are supported by the apparent discrepancy between the distribution and numbers of virus-infected cells and concomitant brain tissue pathology [5, 19]. Whether these soluble factors are indirectly responsible for neuronal damage remains undefined. The identification and regulation of neurotoxins produced from HIV-infected macrophages are central to uncovering how HIV mediates CNS disease. The authors who contributed to this work represent laboratories with overlapping areas of expertise. Broad-based complementary hypotheses regarding HIV neuropathogenesis are now provided.

The course and outcome of unilateral intracranial arteriopathy in 79 children with ischaemic stroke

Arteriopathies are the commonest cause of arterial ischaemic stroke (AIS) in children. Repeated vascular imaging in children with AIS demonstrated the existence of a ‘transient cerebral arteriopathy’ (TCA), characterized by lenticulostriate infarction due to non-progressive unilateral arterial disease affecting the supraclinoid internal carotid artery and its proximal branches. To further characterize the course of childhood arteriopathies, and to differentiate TCA from progressive arterial disease, we studied the long-term evolution of unilateral anterior circulation arteriopathy, and explored predictors of stroke outcome and recurrence. From three consecutive cohorts in London, Paris and Utrecht, we reviewed radiological studies and clinical charts of 79 previously healthy children with anterior circulation AIS and unilateral intracranial arteriopathy of the internal carotid bifurcation, who underwent repeated vascular imaging. The long-term evolution of arteriopathy was classified as progressive or TCA. Clinical and imaging characteristics were compared between both groups. Logistic regression modelling was used to determine possible predictors of the course of arteriopathy, functional outcome and recurrence. After a median follow-up of 1.4 years, 5 of 79 children (6%) had progressive arteriopathy, with increasing unilateral disease or bilateral involvement. In the others (94%), the course of arteriopathy was classified as TCA. In 23% of TCA patients, follow-up vascular imaging showed complete normalization, the remaining 77% had residual arterial abnormalities, with improvement in 45% and stabilization in 32%. Stroke was preceded by chickenpox in 44% of TCA patients, and in none of the patients with progressive arteriopathies. Most infarcts were localized in the basal ganglia. In 14 (19%) of TCA patients, transient worsening of the arterial lesion was demonstrated before the arteriopathy stabilized or improved. Thirteen TCA patients (18%) had a recurrent stroke or TIA. Thirty TCA patients (41%) had a good neurological outcome, compared with none of the five patients with progressive arteriopathy. Arterial occlusion, moyamoya vessels and ACA involvement were more frequent in progressive arteriopathies. Cortical infarct localization was significantly associated with poor neurological outcome (OR 6.14, 95% CI 1.29–29.22, P = 0.02), while there was a trend for occlusive arterial disease to predict poor outcome (OR 3.00, 95% CI 0.98–9.23, P = 0.06). Progressive arteriopathy was associated with recurrence (OR 18.77, 95%CI 1.94–181.97, P = 0.01). The majority of childhood unilateral intracranial anterior circulation arteriopathies (94%) have a course that is consistent with TCA, in which transient worsening is common. Although the arterial inflammation probably causing TCA is ‘transient’, most children are left with permanent arterial abnormalities and residual neurological deficits.

Neuronal apoptosis does not correlate with dementia in HIV infection but is related to microglial activation and axonal damage

To characterize the distribution of apoptotic neurons and their relationships with the stage of disease, a history of HIV-dementia, and the degree of productive HIV infection, microglial activation and axonal damage, we examined the brains of 40 patients. Samples of frontal and temporal cortex, basal ganglia and brain stem were taken post-mortem from 20 patients with AIDS (including three with HIV-dementia, and eight with cognitive disorders that did not fulfil the criteria for HIV-dementia), 10 HIV-positive asymptomatic cases and 10 seronegative controls. Neuronal apoptosis was demonstrated by in situ end labelling in 18 AIDS cases and two pre-AIDS cases; a single apoptotic neuron was present in the temporal cortex of a control. Semiquantitative evaluation showed that the severity of neuronal apoptosis in the cerebral cortex correlated with the presence of cerebral atrophy, but not with a history of HIV dementia. There was no global quantitative correlation between neuronal apoptosis and HIV encephalitis or microglial activation. However, there was some topographical correlation between these changes. In the basal ganglia, apoptotic neurons were much more abundant in the vicinity of multinucleated giant cells and/or p24 expressing cells. Microglial activation was constantly present in these areas. Axonal damage was identified using beta-amyloid-precursor protein (betaAPP) immunostaining in 17 AIDS and eight pre-AIDS brains. Although no global quantitative correlation could be established between axonal damage and neuronal apoptosis there was an obvious topographic correlation supporting the view that axonal damage, either secondary to local microglial activation or due to the intervention of systemic factors, may also contribute to neuronal apoptosis.

Longitudinal study of 94 symptomatic infants with perinatally acquired human immunodeficiency virus infection. Evidence for a bimodal expression of clinical and biological symptoms

To better define the clinical and biological evolution of infants after vertical human immunodeficiency virus type 1 infection, we analyzed 94 consecutive infected patients followed up after their first clinical symptoms. The expression of clinical symptoms and biological abnormalities followed a bimodal distribution, some patients having an early and severe disease and the others having a slowly progressive one. One third of our patients suffered from early onset of opportunistic infection (OI). These patients had a significantly higher incidence of severe encephalopathy compared with patients without OI. The rate of survival at 3 years was 48% +/- 24%. In contrast, the patients without early OI or severe encephalopathy had a probability of survival at 3 years of 97% +/- 3%. This probability was not modified by the occurrence of bacterial infection or lymphoid interstitial pneumonitis. Lymphoid interstitial pneumonitis occurred at a mean age of 29 months, significantly later than OI or severe encephalopathy. Laboratory results at initial examination were correlated with clinical symptoms. Thus, when the number of CD4 lymphocytes was less than 500/mm3, children suffered more frequently from life-threatening symptoms (OI and severe encephalopathy): 15 of 22 vs 14 of 69. The same was true when the lymphocytes did not proliferate after antigenic stimulation, when anti-p18 and/or anti-p25 antibodies were absent in the serum, and when p24 antigen was detected in serum. Finally, severe encephalopathy was associated with low anti-human immunodeficiency virus cerebrospinal fluid antibody titer, whereas 88% of patients with moderate or no encephalopathy had signs of intrathecal anti-human immunodeficiency virus antibody synthesis. In conclusion, a subgroup of patients expressed very early signs of severe immunodeficiency and encephalopathy, whereas the majority of patients had a longer survival and less severe clinical symptoms during their first years of life than previously thought.

Acute and persistent infection of human neural cell lines by human coronavirus OC43

Human coronaviruses (HuCV) are recognized respiratory pathogens. Data accumulated by different laboratories suggest their neurotropic potential. For example, primary cultures of human astrocytes and microglia were shown to be susceptible to an infection by the OC43 strain of HuCV (A. Bonavia, N. Arbour, V. W. Yong, and P. J. Talbot, J. Virol. 71:800-806, 1997). We speculate that the neurotropism of HuCV will lead to persistence within the central nervous system, as was observed for murine coronaviruses. As a first step in the verification of our hypothesis, we have characterized the susceptibility of various human neural cell lines to infection by HuCV-OC43. Viral antigen, infectious virus progeny, and viral RNA were monitored during both acute and persistent infections. The astrocytoma cell lines U-87 MG, U-373 MG, and GL-15, as well as neuroblastoma SK-N-SH, neuroglioma H4, oligodendrocytic MO3.13, and the CHME-5 immortalized fetal microglial cell lines, were all susceptible to an acute infection by HuCV-OC43. Viral antigen and RNA and release of infectious virions were observed during persistent HuCV-OC43 infections ( approximately 130 days of culture) of U-87 MG, U-373 MG, MO3.13, and H4 cell lines. Nucleotide sequences of RNA encoding the putatively hypervariable viral S1 gene fragment obtained after 130 days of culture were compared to that of initial virus input. Point mutations leading to amino acid changes were observed in all persistently infected cell lines. Moreover, an in-frame deletion was also observed in persistently infected H4 cells. Some point mutations were observed in some molecular clones but not all, suggesting evolution of the viral population and the emergence of viral quasispecies during persistent infection of H4, U-87 MG, and MO3.13 cell lines. These results are consistent with the potential persistence of HuCV-OC43 in cells of the human nervous system, accompanied by the production of infectious virions and molecular variation of viral genomic RNA.

Consensus statement: evaluation of new and existing therapeutics for pediatric multiple sclerosis

New therapies are being evaluated by clinical trials and, if efficacious, introduced for the treatment of adult MS. The role of these new and existing agents in the management of pediatric MS has yet to be defined. Pediatric investigation plans are now required by the Food and Drug Administration and European Medicines Agency for approval of new biological agents, providing an important opportunity to gather much-needed data for clinicians caring for children and adolescents with MS. However, challenges include the small number of patients, and the need for efficient yet comprehensive study designs incorporating factors necessary to inform the clinical care of children with MS. The elected Steering committee of the International Pediatric MS Study Group (IPMSSG) conducted a structured review of existing data on the disease-modifying therapies in pediatric MS and developed a consensus statement, which was further modified by the IPMSSG general membership, using an online survey tool. Fifty-one IPMSSG members from 21 countries responded to the survey, and 50 approved the final statement. Consensus recommendations regarding use of existing first- and second-line therapies, as well as a proposed definition for inadequate treatment response, are presented. Recommendations for the use and evaluation of emerging therapies (currently in phase III clinical trials or recently approved for adult MS) are discussed. The IPMSSG endorses the inclusion of pediatric MS patients in trials evaluating appropriate new and emerging therapies. Mechanisms for conducting high-impact, multicenter studies, including long-term follow-up in pediatric MS, are required to ensure that all MS patients, irrespective of age, benefit from advances in MS therapeutics.

Stroke in childhood: outcome and recurrence risk by mechanism in 59 patients

This paper describes 59 patients, 3 months to 16 years of age, who were seen consecutively in the same center for cerebral arterial infarction. It focuses on the mechanism of stroke. The pathophysiologic process could be established for 78% of the children. Arteriopathic stroke (31 patients, or 53%) was the most common. The arteriopathies were either progressive (moyamoya in 4 patients, or 7%) or nonprogressive (27 patients, or 46%). The latter form occurred in two patterns: dissection of cervicocephalic arteries (12 patients, or 20%) and transient cerebral arteriopathy of unknown origin but probably angiitis (15 patients, or 25%). Cardiac or transcardiac embolic stroke occurred in 12% of the series and systemic diseases in 14%. There was a favorable outcome in 70% of patients having stroke due to nonprogressive arterial disease and stroke due to unidentified mechanisms. In contrast, only 26% of patients with embolic stroke, systemic disease, or moyamoya had a favorable outcome. Recurrences were more frequent and severe in this latter group. It is concluded that it is important to determine the mechanism of childhood stroke, because it strongly influences outcome, the recurrence risk, and treatment choice.

Vemurafenib for Refractory Multisystem Langerhans Cell Histiocytosis in Children: An International Observational Study

PURPOSE

Off-label use of vemurafenib (VMF) to treat BRAFV600E mutation-positive, refractory, childhood Langerhans cell histiocytosis (LCH) was evaluated.

PATIENTS AND METHODS

Fifty-four patients from 12 countries took VMF 20 mg/kg/d. They were classified according to risk organ involvement: liver, spleen, and/or blood cytopenia. The main evaluation criteria were adverse events (Common Terminology Criteria for Adverse Events [version 4.3]) and therapeutic responses according to Disease Activity Score.

RESULTS

LCH extent was distributed as follows: 44 with positive and 10 with negative risk organ involvement. Median age at diagnosis was 0.9 years (range, 0.1 to 6.5 years). Median age at VMF initiation was 1.8 years (range, 0.18 to 14 years), with a median follow-up of 22 months (range, 4.3 to 57 months), whereas median treatment duration was 13.9 months (for 855 patient-months). At 8 weeks, 38 complete responses and 16 partial responses had been achieved, with the median Disease Activity Score decreasing from 7 at diagnosis to 0 (P < .001). Skin rash, the most frequent adverse event, affected 74% of patients. No secondary skin cancer was observed. Therapeutic plasma VMF concentrations (range, 10 to 20 mg/L) seemed to be safe and effective. VMF discontinuation for 30 patients led to 24 LCH reactivations. The blood BRAFV600E allele load, assessed as circulating cell-free DNA, decreased after starting VMF but remained positive (median, 3.6% at diagnosis, and 1.6% during VMF treatment; P < .001) and was associated with a higher risk of reactivation at VMF discontinuation. None of the various empirical therapies (hematopoietic stem-cell transplantation, cladribine and cytarabine, anti-MEK agent, vinblastine, etc) used for maintenance could eradicate the BRAFV600E clone.

CONCLUSION

VMF seemed safe and effective in children with refractory BRAFV600E-positive LCH. Additional studies are needed to find effective maintenance therapy approaches.

Human microglial cells: characterization in cerebral tissue and in primary culture, and study of their susceptibility to HIV-1 infection

Neuropathological studies have shown that human immunodeficiency virus type 1-infected cells within the brain express several markers characteristic of macrophages and could either be microglial cells, or monocytes invading the CNS, or both. To better define the target cells of human immunodeficiency virus type 1 within the brain, we have studied human microglial cells, both in vivo and in vitro, and compared them to monocytes for their antigenic markers and their susceptibility to human immunodeficiency virus type 1 infection. Brain-derived macrophages were isolated from primary cortical and spinal cord cultures obtained from 8 to 12-week-old human embryos. The isolated cells presented esterase activity, phagocyted zymosan particles, expressed several (Fc receptors, and CD68/Ki-M7 and CD11b/CR3 receptors) of the macrophagic antigenic markers, and appeared to be resident microglial cells from human embryonic brain. Conversely, brain-derived macrophages did not express antigens CD4, CD14, or CD68/Ki-M6, which are easily detected on freshly isolated monocytes. Using these antigenic differences between isolated microglial cells and monocytes, we have observed that two populations of macrophages could be individualized. In the normal adult brain, microglial cells were numerous in both the gray and the white matter. The infrequent cells sharing antigens with monocytes were found almost exclusively around vessels. In 8 to 12-week-old human embryos, microglial cells were found in both the parenchyma and the germinative layer. Cells sharing antigens with monocytes were only found at the top of and inside the germinative layer. In brain tissue from patients with human immunodeficiency virus type 1 encephalitis, cells sharing antigens with monocytes are abundant not only around the vessels but also in the parenchyma. In double-labeling experiments, human immunodeficiency virus type 1-infected cells showed monocyte antigens. Finally, microglial cells also differ from monocytes in their in vitro susceptibility to human immunodeficiency virus type 1 infection; after stimulation by r-TNF alpha or GmCSF, monocytes but not microglial cells can replicate human immunodeficiency virus type 1. This in vitro difference in human immunodeficiency virus type 1 susceptibility between monocytes and microglial cells together with the presence of monocytic antigens within the brain tissue of human immunodeficiency virus type 1-infected patients suggest that human immunodeficiency virus type 1-infected cells within the brain are either monocytes that have crossed the blood-brain barrier and spread through the tissue or perivascular microglial cells that, after phagocyting infected blood lymphocytes, subsequently contain viral antigen and migrate to brain tissue.

Identification of a hemagglutinin-specific idiotype associated with reovirus recognition shared by lymphoid and neural cells

A xenogeneic antiserum raised to antireovirus immunoglobulin was used to define an idiotypic determinant present on antibodies to reovirus type 3 hemagglutinin. The same idiotype was identified on nonimmune lymphoid cells and on neuronal cells that specifically bind the hemagglutinin of type 3 reovirus. This idiotypic determinant, called Id3, is shared by (a) a monoclonal antibody to the neutralization site of hemagglutinin from type 3 reovirus; (b) BALB/c serum antibodies to the hemagglutinin of reovirus type 3; (c) R1.1, a murine thymoma cell line that binds reovirus type 3; (d) primary cultures of murine neuronal cells. The presence of an idiotype shared by antihemagglutinin antibodies and by structures on nonlymphoid cells suggests a general relationship between disparate receptors that recognize a common determinant. Furthermore, this suggests a novel approach for the study of viral receptor interactions and for analysis of mechanisms of autoimmune responses.

Human immunodeficiency virus type 1-infected monocytic cells can destroy human neural cells after cell-to-cell adhesion

Primary cultures of human embryonic neurons and astrocytes have been used to test the interactions between neural cells and either human immunodeficiency virus type 1 (HIV-1) or HIV-1-infected monocytes. After direct infection with HIV-1, neither morphological alteration of neurons and astrocytes nor signs of viral replication were observed. Similarly, cultured human neurons and astrocytes were resistant to incubation with the supernatant of HIV-1-infected U937 cells, a human monoblastoid cell line. In contrast, HIV-1-infected U937 monocytic cells adhered to neural cells and induced large plaques of necrosis surrounding them. This cytopathic effect began at the time of viral replication (day 16 after infection). Its intensity depended on that of viral replication, and its range was identical to the region of diffusion of viral antigens, as judged by immunocytochemistry. The cytopathic effect was not dependent on the release of free radicals. It could not be induced by cytokines or cytokine-stimulated U937 cells. It is likely that this cytopathic effect depends on the release of viral antigens either within the site of adherence itself or within close range of the astrocyte membrane.

Transient cerebral arteriopathy: a disorder recognized by serial angiograms in children with stroke

Repeated clinical evaluation and cerebral arteriography during the evolution of ischemic strokes of idiopathic origin allowed us to characterize a transient cerebral arteriopathy. We retrospectively studied the clinical characteristics, course, and neuroimaging features of this disorder in nine children. Of 34 children with ischemic strokes seen consecutively between 1984 and 1995, 9 (26%) were diagnosed as having transient attack of the cerebral arterial wall, termed transient cerebral arteriopathy. All of these patients had previously been in good health. The mean age at the time of the first stroke was 6 years (range, 2 9/12 years to 13 4/12 years). All children presented with acute hemiplegia. A recurrence of the stroke took place 3 months at the latest after the initial infarct in three children (mean clinical follow-up 2 7/12 years). Cerebral imaging in all the patients showed small subcortical infarcts located in basal ganglia or internal capsule. Arteriography revealed multifocal lesions of the arterial wall (focal stenosis or segmental narrowing), mostly located in the initial parts of basal arteries of the carotid system. Longitudinal arteriographic follow-up showed initial worsening of these arterial lesions (n = 5) for a maximum duration of 7 months followed by complete regression (n = 2), improvement (n = 5), or stabilization of the lesions (n = 2). Five patients had a complete clinical recovery. Further studies are necessary to confirm a presumed inflammatory cause of this arteriopathy.

Persistent infection of human oligodendrocytic and neuroglial cell lines by human coronavirus 229E

Human coronaviruses (HuCV) cause common colds. Previous reports suggest that these infectious agents may be neurotropic in humans, as they are for some mammals. With the long-term aim of providing experimental evidence for the neurotropism of HuCV and the establishment of persistent infections in the nervous system, we have evaluated the susceptibility of various human neural cell lines to acute and persistent infection by HuCV-229E. Viral antigen, infectious virus progeny and viral RNA were monitored during both acute and persistent infections. The astrocytoma cell lines U-87 MG, U-373 MG, and GL-15, as well as neuroblastoma SK-N-SH, neuroglioma H4, and oligodendrocytic MO3.13 cell lines, were all susceptible to an acute infection by HuCV-229E. The CHME-5 immortalized fetal microglial cell line was not susceptible to infection by this virus. The MO3.13 and H4 cell lines also sustained a persistent viral infection, as monitored by detection of viral antigen and infectious virus progeny. Sequencing of the S1 gene from viral RNA after approximately 130 days of infection showed two point mutations, suggesting amino acid changes during persistent infection of MO3.13 cells but none for H4 cells. Thus, persistent in vitro infection did not generate important changes in the S1 portion of the viral spike protein, which was shown for murine coronaviruses to bear hypervariable domains and to interact with cellular receptor. These results are consistent with the potential persistence of HuCV-229E in cells of the human nervous system, such as oligodendrocytes and possibly neurons, and the virus's apparent genomic stability.

Derivatized dextrans mimic heparin as stabilizers, potentiators, and protectors of acidic or basic FGF

Acidic and basic fibroblast growth factors (aFGF and bFGF) belong to a family of structurally related polypeptides characterized by a high affinity for heparin. a and bFGF display mitogenic activity for many cell types. Biological activity is strongly potentiated by heparin which stabilizes their molecular conformation by preventing physicochemical or enzymatic degradation. In our previous study we have shown that a water-soluble derivatized dextran named DDE, containing 82.2% methyl carboxylic acid groups, 6.1% benzylamide, and 5.6% sulfonate with a specific anticoagulant activity equivalent to heparin of 0.5 IU/mg could potentiate the mitogenic activity of aFGF on CCL39 cells. Optimal concentrations for maximal potentiation of 400 micrograms/ml and 20 micrograms/ml were obtained respectively for DDE and heparin. In the present report, we have uncovered the fact that several carboxymethyl benzylamide sulfonate dextrans differing in degree and positioning of the substituent groups can mimic heparin in regard to the protection, stabilization, and potentiating effects with aFGF or bFGF. Our data establishes that the dextran derivatives studied can act as potentiating agents for FGFs. Native dextran (DDA) had no effect. Dextran derivatives can also protect aFGF and bFGF from heat as well as from pH denaturation, and against trypsic and chymotrypsic degradation. The dextran derivative DDI (82% methylcarboxylic acid, 23% benzylamide, 13% sulfonate) was studied in greater detail and exhibited a greater protection for bFGF and a lesser protecting effect for aFGF than heparin. Derivatized dextrans which have very weak anticoagulant activity are of great interest as alternatives to heparin for use as stabilizers, potentiators, protectants, and slow-release matrices for FGFs in pharmaceutical formulations.

HIV-1 envelope proteins gp120 and gp160 potentiate NMDA-induced [Ca2+]i increase, alter [Ca2+]i homeostasis and induce neurotoxicity in human embryonic neurons

The envelope glycoprotein gp120 of the human immunodeficiency virus HIV-1 has been proposed to cause neuron death in developing murine hippocampal cultures and rat retinal ganglion cells. In the present study, cultured human embryonic cerebral and spinal neurons from 8- to 10-week-old embryos were used to study the neurotoxic effect of gp120 and gp160. Electrophysiological properties as well as N-methyl-D-aspartate (NMDA)-induced current were recorded from neurons maintained in culture for 10-30 days. Neither voltage-activated sodium or calcium currents nor NMDA-induced currents were affected by exposure of neurons to 250 pM gp120 or gp160. In contrast, when neurons were subjected to photometric measurements using the calcium dye indo-1 to monitor the intracellular free Ca2+ concentration ([Ca2+])i, gp120 and gp160 (20-250 pM) potentiated the large rises in [Ca2+]i induced by 50 microM NMDA. The potentiation of NMDA-induced Ca2+ responses required the presence of Ca2+ in the medium, and was abolished by the NMDA antagonist D-2-amino-5-phosphonovalerate (AP5) and the voltage-gated Ca2+ channel inhibitor nifedipine. Moreover, exposure of a subpopulation of spinal neurons (25% of the cells tested) to 20-250 pM gp120 or gp160 resulted in an increase in [Ca2+]i that followed three patterns: fluctuations not affected by AP5, a single peak, and the progressive and irreversible rise of [Ca2+]i. The neurotoxicity of picomolar doses of gp120 and gp160 cultures was estimated by immunofluorescence and colorimetric assay. Treatment of cultures with AP5 or nifedipine reduced gp120-induced toxicity by 70 and

Human immunodeficiency virus type 1 and its coat protein gp120 induce apoptosis and activate JNK and ERK mitogen-activated protein kinases in human neurons

Detection of apoptotic neurons and microglial cells in the brains of human immunodeficiency virus type 1 (HIV-1)-infected patients has suggested that programmed cell death may be implicated in the physiopathology of HIV-1 encephalopathy. To analyze in vitro the intracellular signals induced by HIV-1 in human neurons and the associated neuronal death, we tested cultured human central nervous system (CNS) cells for apoptosis induced by HIV-1 and gp120 and for signaling pathways activated by gp120. HIV-1 and gp120 induced apoptosis of neurons and microglial cells but not of astrocytes or transformed microglial cells. Gp120 activated c-Jun N-terminal kinase (JNK) and p42 extracellular-regulated kinase (ERK) in primary CNS cells, with an early peak of activation at 2 to 5 minutes that was not present when pure microglial or astrocyte cultures were tested, followed by a late and sustained activation (10 and 60 minutes) in primary and enriched glial cell cultures as well as in transformed microglial cells. This demonstrates that gp120 could be an effector of HIV-1-induced apoptosis in the CNS and act directly on neuronal and glial cells.

Vein of Galen malformation. Endovascular management of 43 cases

Since 1984, 43 patients with true vein of Galen aneurysmal malformations have been referred to us and managed according to our patient selection, technique, and follow-up guidelines. Thirty-four were embolized transarterially with bucrilate (isobutyl cyanoacrylate) or enbucrilate (N-butyl cyanoacrylate) embolization. No cutdown or hypotension during or after the embolization was used and no balloon catheter was employed. Forty-seven percent of the children had a completely occluded lesion which was confirmed when the child was at least 6 months of age at the follow-up angiographic examination; 52.9% were found to be completely normal or only to have mild cardiac failure that could be treated medically or moderate macrocephaly without neurological symptoms or mental retardation. In the embolized group 5.8% died as a result of the wrong treatment (1 case) or poor timing of embolization 3 days after ventricular shunting (1 case). The overall mortality (embolized and non-embolized groups) in the neonatal children was 27.7% with a total of 18.6% for all ages. Complete morphological exclusion of the arteriovenous malformation was accomplished in 41.9%; 74.4% of all children referred are now clinically normal or present moderate mental retardation which is diminishing. There was 3% neurological morbidity in the embolized group (only following the venous approach) in 78 sessions and more than 100 arteries embolized. These results compare favorably with surgical or other techniques of arterial embolization (balloon or particles), as well as transvenous (transtorcular or transfemoral) embolization, where the morbidity and mortality are significantly higher and the late clinical evaluation is seldom satisfactory.(ABSTRACT TRUNCATED AT 250 WORDS)

CNS involvement at the onset of primary hemophagocytic lymphohistiocytosis

OBJECTIVES

To differentiate onset of CNS involvement in primary hemophagocytic lymphohistiocytosis (HLH) from that of other CNS inflammatory diseases and to identify early symptoms linked to abnormal cognitive outcome.

METHODS

Forty-six children with primary HLH who had neurologic evaluation within 2 weeks and brain MRI within 6 months of diagnosis were included. Initial symptoms, CSF study, brain MRI, and neurologic outcome were assessed. Brain MRIs were compared with those of 44 children with acute disseminated encephalomyelitis (ADEM).

RESULTS

At disease onset, 29 children (63%) had neurologic symptoms and 7 (15%) had microcephaly. Twenty-three (50%) children had abnormal CSF study, but only 15 (33%) had abnormal brain MRI. The latter showed that patients with HLH, unlike patients with ADEM, had symmetric periventricular lesions, without thalamic and brainstem involvement and with infrequent hyposignal intensity on T1. At the end of follow-up (3.6 ± 3.6 years), 17 of the 28 (61%) surviving patients had normal neurologic status, 5 (18%) had a severe neurologic outcome, and 6 (21%) had mild cognitive difficulties. Abnormal neurologic outcome was not influenced by age or type of genetic defect, but by the presence of neurologic symptoms, MRI lesions, or abnormal CSF study at onset. Early clinical and MRI symptoms may regress after treatment.

CONCLUSION

Neurologic symptoms are frequent at the onset of primary HLH and are mostly associated with abnormal CSF findings, but with normal brain MRI. In cases of abnormal brain MRI, the observed lesions differ from those of ADEM.

HIV-1-related encephalopathy in infants compared with children and adults. French Pediatric HIV Infection Study and the SEROCO Group

OBJECTIVE

To characterize the specificities of HIV-1-related encephalopathy in children.

METHODS

Comparison of patients from the French Perinatal Cohort of children born to HIV-1-infected mothers and followed from birth with the French SEROCO Cohort of adults with a known date of infection. Our study examines 1) the characteristics of encephalopathy with onset before 1 year, after 1 year, and in adults, and 2) the maternal and birth characteristics of infants who developed AIDS before 1 year and went on to develop either encephalopathy or opportunistic infection.

RESULTS

The incidence of encephalopathy was higher in children than in adults during the first year (9.9% versus 0.3%) and intermediate during the second year (4.2% versus 0%) after infection but was similar thereafter (less than 1% per year in each group). The resulting cumulative incidence at 7 years postinfection reached 16% in children and 5% in adults. Encephalopathy that developed before 1 year 1) was more frequently an isolated symptom of AIDS, 2) was associated with a reduction of intrauterine brain growth, 3) was associated with a very low level of HIV-1 RNA in CSF, 4) occurred at a higher level of immunocompetence after taking into account the decrease in CD4 lymphocytes with age, and 5) was not prevented by zidovudine treatment during gestation.

CONCLUSIONS

Early encephalopathy in infants has a different pathophysiologic mechanism than that occurring in children, which in turn shows similarities with that observed in adults. Early encephalopathy is probably related to the occurrence of pathologic events during late fetal life.

Detection of measles virus RNA in lymphocytes from peripheral-blood and brain perivascular infiltrates of patients with subacute sclerosing panencephalitis

To clarify the relation between lymphocytes and measles virus in subacute sclerosing panencephalitis, we used in situ hybridization and a cloned measles virus DNA probe, specific for nucleocapsid protein, to detect measles virus RNA sequences in circulating lymphocytes and brain perivascular cuffs of patients with subacute sclerosing panencephalitis. Seventy to 90 per cent of peripheral mononuclear cells from three such patients were found to contain measles virus RNA sequences. In contrast, only a few infected cells were observed in four seropositive adults (0.1 to 5 per cent) and three age-matched children (10 to 15 per cent) used as controls. In one sample of brain tissue from a patient with subacute sclerosing panencephalitis, viral RNA sequences were also detected in nerve cells and in numerous cells from the perivascular infiltrates. In contrast, no hybridization was observed in brain tissue from a patient with herpetic encephalitis and from a patient with postlymphoma encephalitis. We conclude that measles virus has a strong tropism for lymphocytes and nerve cells in subacute sclerosing panencephalitis and that lymphocytes may be involved in the pathogenesis of the disease.

Mitogenic and in vitro angiogenic activity of human recombinant heparin affin regulatory peptide

We have previously described the purification of a heparin binding growth factor from adult bovine brain named heparin affin regulatory peptide (HARP), which was identical to an uterus derived growth factor named pleiotrophin and to a developmentally regulated neurite promoting factor named heparin-binding growth associated molecule. However, for yet unclear reasons, the mitogenic activity of this purified polypeptide following isolation from animal tissue extracts is a subject of controversy, due to conflicting and irreproducible data when produced by recombinant DNA technologies in E. coli or insect cells. The purified protein was inactive in mitogenic assays but the natural molecule was active in assay of neurite outgrowth. In order to clarify these conflicting results and to obtain a recombinant protein free from other contaminating heparin-binding growth factors, we have cloned human cDNA encoding human HARP, engineered its expression in NIH 3T3 cells and characterised the resulting recombinant polypeptide. Purified recombinant HARP displayed mitogenic activity for capillary endothelial cells with half-maximal stimulation at approximately 1 ng/ml (55 pM) and induced angiogenesis in an in vitro model. Interestingly, while the NH2 terminal sequence of tissue purified HARP was NH2-GKKEKPEKK, the NH2 terminal sequence of the biologically active recombinant protein was NH2-AEAGKKEKPEKK, corresponding to a three amino acid extended form.

Parental origin of de novo MECP2 mutations in Rett syndrome

Rett syndrome (RTT) is a neurodevelopmental disorder occurring almost exclusively in females as sporadic cases. Recently, DNA mutations in the MECP2 gene have been detected in approximately 70% of patients with RTT. To explain the sex-limited expression of RTT, it has been suggested that de novo X-linked mutations occur exclusively in male germ cells resulting therefore only in affected daughters. To test this hypothesis, we have analysed 19 families with RTT syndrome due to MECP2 molecular defects. In seven informative families we have found by DHPLC a nucleotide variant which could be used to differentiate between the maternal and the paternal allele. In each subject investigated from these families, we have amplified specifically each allele and sequenced allele-specific PCR products to identify the allele bearing the mutation as well as the parental origin of each X chromosome. This approach allowed us to determine the parental origin of de novo mutations in all informative families. In five cases, the de novo MECP2 mutations have a paternal origin and in the two other cases a maternal origin. In all transitions at CpG, the de novo mutation observed was of paternal origin. The high frequency of male germ-line transmission of the mutation (71% of RTT informative cases) is consistent with a predominant occurrence of the disease in females.