A Rare Etiology for Ascending Paralysis in an Infant.

An 11-month-old male infant with ascending paralysis had an unremarkable initial cerebrospinal fluid (CSF) analysis and imaging. Progressive neurological symptoms resulted in repeated CSF sampling, microscopy, and plasma microbial cell-free DNA next-generation sequencing analysis, that in combination with epidemiology, confirmed the diagnosis.

Blockade of placental growth factor reduces vaso-occlusive complications in murine models of sickle cell disease.

Vaso-occlusive crisis (VOC) is the most common and debilitating complication of sickle cell disease (SCD); recurrent episodes cause organ damage and contribute to early mortality. Plasma placental growth factor (PlGF) levels are elevated in SCD and can further increase under hypoxic conditions in SCD mice. Treatment with a PlGF-neutralizing antibody (anti-PlGF Ab) in SCD mice reduced levels of monocyte chemoattractant protein-3, eotaxin, macrophage colony-stimulating factor, and plasminogen activator inhibitor-1 significantly, and of macrophage-derived chemokine and macrophage inflammatory protein-3ß moderately; this may contribute to inhibition of leukocyte recruitment, activation, and thrombosis. In subsequent experiments, anti-PlGF Ab treatment significantly reduced plasma lactate dehydrogenase levels, indicating possible reduction in cellular destruction and/or hemolysis. Histopathology studies revealed decreased incidence and severity of congestion in the lungs and spleen with repeated anti-PlGF Ab treatment. Furthermore, anti-PlGF Ab significantly reduced vaso-occlusion events under hypoxic conditions in a modified dorsal skinfold chamber model in SCD mice. Therefore, elevated PlGF levels may contribute to recruitment and activation of leukocytes. This can subsequently lead to increased pathology of affected organs in addition to mediating acute hypoxia/reoxygenation-triggered vaso-occlusion under SCD conditions. Thus, targeting PlGF may offer a therapeutic approach to reduce acute VOC and possibly alleviate long-term vascular complications in patients with SCD.

A Case of Escherichia coli Hemolytic Uremic Syndrome in a 10-Year-Old Male With Severe Neurologic Involvement Successfully Treated With Eculizumab.

Hemolytic uremic syndrome (HUS) can be classified as typical and atypical, and the treatment recommendations currently differ between the 2 types. Eculizumab is recommended as first-line treatment for atypical HUS; however, its use in typical HUS has been controversial. We report a case of a 10-year-old male with severe neurologic impairment who was successfully treated with eculizumab, which was started 4 days after onset of neurologic symptoms. Our case supports the use of eculizumab in typical HUS with neurologic involvement, even when given later in the course, as the pathophysiology of typical HUS has been shown to involve activation of the complement pathway, similar to atypical HUS. Further studies are required to establish the efficacy and duration of eculizumab use in this patient population.

Emergency Department Presentations of Anti-N-Methyl-D-Aspartate Receptor Encephalitis.

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is an acute autoimmune neurological disorder that presents with acute to subacute psychiatric and/or neurological complaints including new onset behavioral changes that may evolve to psychosis and catatonia, cognitive decline, new onset seizures, progressive encephalopathy, and/or movement disorders. Female teens and adults often have an associated ovarian teratoma as an underlying etiology, but most pediatric patients do not have an identifiable associated neoplasm. The diagnosis requires confirmatory serum and/or cerebrospinal fluid analysis findings of anti-NMDAR antibody titers. It can be misdiagnosed as a psychiatric condition or a viral encephalitis. The clinical features that distinguish anti-NMDAR encephalitis from a primary psychiatric disorder are the acute onset of the mood and behavioral changes with no history, the waxing and waning of consciousness (delirium/encephalopathy), and primary neurological features such as seizures and abnormal involuntary movements, including dyskinesias and dystonias. The prognosis is improved with earlier recognition and prompt immunotherapy treatment, making this an important diagnosis for emergency physicians.

A specific antidote for reversal of anticoagulation by direct and indirect inhibitors of coagulation factor Xa.

Inhibitors of coagulation factor Xa (fXa) have emerged as a new class of antithrombotics but lack effective antidotes for patients experiencing serious bleeding. We designed and expressed a modified form of fXa as an antidote for fXa inhibitors. This recombinant protein (r-Antidote, PRT064445) is catalytically inactive and lacks the membrane-binding γ-carboxyglutamic acid domain of native fXa but retains the ability of native fXa to bind direct fXa inhibitors as well as low molecular weight heparin-activated antithrombin III (ATIII). r-Antidote dose-dependently reversed the inhibition of fXa by direct fXa inhibitors and corrected the prolongation of ex vivo clotting times by such inhibitors. In rabbits treated with the direct fXa inhibitor rivaroxaban, r-Antidote restored hemostasis in a liver laceration model. The effect of r-Antidote was mediated by reducing plasma anti-fXa activity and the non-protein bound fraction of the fXa inhibitor in plasma. In rats, r-Antidote administration dose-dependently and completely corrected increases in blood loss resulting from ATIII-dependent anticoagulation by enoxaparin or fondaparinux. r-Antidote has the potential to be used as a universal antidote for a broad range of fXa inhibitors.

Haploinsufficiency of STK11 and neighboring genes cause a contiguous gene syndrome including Peutz-Jeghers phenotype.

We report on clinical and molecular findings of a 15-year-old female referred to our genetics clinic for a diagnostic evaluation due to mild developmental delay, submucosal cleft palate, and seizure disorder. Chromosomal microarray technology revealed a cancer predisposition due to a terminal deletion on chromosome 19p that includes the tumor suppressor gene STK11. In addition to abnormal lip pigmentation on exam, further diagnostic workup with upper and lower gastrointestinal screening confirmed polyps consistent with Peutz-Jeghers syndrome. The purpose of this study is to present a full clinical description of a patient with a rare 19p13.3 chromosomal deletion and review the current literature of this newly emerging contiguous gene deletion syndrome. It also supports the screening for complications of Peutz-Jeghers syndrome in all patients with this deletion.

A novel mutation in the HSD17B10 gene of a 10-year-old boy with refractory epilepsy, choreoathetosis and learning disability.

Hydroxysteroid (17beta) dehydrogenase 10 (HSD10) is a mitochondrial multifunctional enzyme encoded by the HSD17B10 gene. Missense mutations in this gene result in HSD10 deficiency, whereas a silent mutation results in mental retardation, X-linked, syndromic 10 (MRXS10). Here we report a novel missense mutation found in the HSD17B10 gene, namely c.194T>C transition (rs104886492), brought about by the loss of two forked methyl groups of valine 65 in the HSD10 active site. The affected boy, who possesses mutant HSD10 (p.V65A), has a neurological syndrome with metabolic derangements, choreoathetosis, refractory epilepsy and learning disability. He has no history of acute decompensation or metabolic acidosis whereas his urine organic acid profile, showing elevated levels of 2-methyl-3-hydroxybutyrate and tiglylglycine, is characteristic of HSD10 deficiency. His HSD10 activity was much lower than the normal control level, with normal ß-ketothiolase activity. The c.194T>C mutation in HSD17B10 can be identified by the restriction fragment polymorphism analysis, thereby facilitating the screening of this novel mutation in individuals with intellectual disability of unknown etiology and their family members much easier. The patient's mother is an asymptomatic carrier, and has a mixed ancestry (Hawaiian, Japanese and Chinese). This demonstrates that HSD10 deficiency patients are not confined to a particular ethnicity although previously reported cases were either Spanish or German descendants.

Critical role for Syk in responses to vascular injury.

Although current antiplatelet therapies provide potent antithrombotic effects, their efficacy is limited by a heightened risk of bleeding and failure to affect vascular remodeling after injury. New lines of research suggest that thrombosis and hemorrhage may be uncoupled at the interface of pathways controlling thrombosis and inflammation. Here, as one remarkable example, studies using a novel and highly selective pharmacologic inhibitor of the spleen tyrosine kinase Syk [PRT060318; 2-((1R,2S)-2-aminocyclohexylamino)-4-(m-tolylamino)pyrimidine-5-carboxamide] coupled with genetic experiments, demonstrate that Syk inhibition ameliorates both the acute and chronic responses to vascular injury without affecting hemostasis. Specifically, lack of Syk (murine radiation chimeras) attenuated shear-induced thrombus formation ex vivo, and PRT060318 strongly inhibited arterial thrombosis in vivo in multiple animal species while having minimal impact on bleeding. Furthermore, leukocyte-platelet-dependent responses to vascular injury, including inflammatory cell recruitment and neointima formation, were markedly inhibited by PRT060318. Thus, Syk controls acute and long-term responses to arterial vascular injury. The therapeutic potential of Syk may be exemplary of a new class of antiatherothrombotic agents that target the interface between thrombosis and inflammation.

Lumbar puncture needle length determination.

INTRODUCTION: Appropriate lumbar puncture (LP) needle length selection may be more difficult for less experienced practitioners or for patients who are of unusually large or small body habitus. The purpose of this study is to determine if there is a relationship between body height and weight, and the percutaneous depth to the spinal canal, which can more reliably assist in selecting an LP needle length. METHODS: This is a retrospective cohort study of patients who received an abdominal computed tomographic scan (for any reason) from July 1999 to December 2000. Lumbar puncture depth was measured on the computed tomographic scan and was used to derive a formula. RESULTS: The final data pool consisted of 175 patients, aged 25 days to 80 years, with height of 48 to 181.5 cm, weight of 3.0 to 127.3 kg, and body mass index of 11.7 to 49.7 kg/m2. Using this data set, the formula for predicting the required LP depth is (weight in kilograms, height in centimeters): LP depth (cm) = 1 + 17 x weight/height. Using linear regression comparing the skin to mid-spinal canal depth measurements with the calculated LP depths, R2 was 0.81 (P < .001). This formula selected a needle that was too short in 6% (less than that of 4 other previously published LP needle length selection methods) and a needle that was too long in 31%. CONCLUSION: Compared with other formulas, this formula might be a more reliable predictor for estimating the required LP needle length, but this must be validated by further studies. It should be noted that none of the formulas were perfect.

Platelet and osteoclast beta3 integrins are critical for bone metastasis.

Mice with a targeted deletion of beta3 integrin were used to examine the process by which tumor cells metastasize and destroy bone. Injection of B16 melanoma cells into the left cardiac ventricle resulted in osteolytic bone metastasis in 74% of beta3+/+ mice by 14 days. In contrast, only 4% of beta3-/- mice developed bone lesions. Direct intratibial inoculation of tumor resulted in marrow replacement by tumor in beta3-/- mice, but no associated trabecular bone resorption as seen inbeta3+/+ mice. Bone marrow transplantation studies showed that susceptibility to bone metastasis was conferred by a bone marrow-derived cell. To dissect the roles of osteoclast and platelet beta3 integrins in this model of bone metastasis, osteoclast-defective src-/- mice were used. Src-null mice were protected from tumor-associated bone destruction but were not protected from tumor cell metastasis to bone. In contrast, a highly specific platelet aggregation inhibitor of activated alphaIIbbeta3 prevented B16 metastases. These data demonstrate a critical role for platelet alphaIIbbeta3 in tumor entry into bone and suggest a mechanism by which antiplatelet therapy may be beneficial in preventing the metastasis of solid tumors.

Inducible and selective transgene expression in murine vascular endothelium.

We have developed a system utilizing the murine Tie2 promoter/enhancer coupled with the "tetracycline-on" regulatory elements to create a model that allows regulated and selective expression of a beta-galactosidase (betaGal) reporter transgene in the adult murine vascular endothelium. Two independent lines of viable and fertile mice were characterized, and they exhibit minimal betaGal expression under basal conditions. In response to exogenous doxycycline (Dox), selective expression of betaGal was demonstrated in the vascular endothelium of all tissues examined. En face analyses of the aorta and its principle branches indicate that the vast majority of lumenal endothelial cells express the transgene. Inducible betaGal expression also extends to the endocardium and the microvasculature of all organs. There is no evidence of specific transgene expression in nonendothelial cell types. Induction of the betaGal was effectively achieved after 3 days of oral Dox treatment and persisted for over 3 mo with continuous administration. This model can now be widely applied to study the role of specific genes in the phenotype of adult murine vasculature.

Blockade of platelet-derived growth factor or its receptors transiently delays but does not prevent fibrous cap formation in ApoE null mice.

Platelet-derived growth factor (PDGF) is a potent stimulant of smooth muscle cell migration and proliferation in culture. To test the role of PDGF in the accumulation of smooth muscle cells in vivo, we evaluated ApoE -/- mice that develop complex lesions of atherosclerosis. Fetal liver cells from PDGF-B-deficient embryos were used to replace the circulating cells of lethally irradiated ApoE -/- mice. One month after transplant, all monocytes in PDGF-B -/- chimeras are of donor origin (lack PDGF), and no PDGF-BB is detected in circulating platelets, primary sources of PDGF in lesions. Although lesion volumes are comparable in the PDGF-B +/+ and -/- chimeras at 35 weeks, lesions in PDGF-B -/- chimeras contain mostly macrophages, appear less mature, and have a reduced frequency of fibrous cap formation as compared with PDGF-B +/+ chimeras. However, after 45 weeks, smooth muscle cell accumulation in fibrous caps is indistinguishable in the two groups. Comparison of elicited peritoneal macrophages by RNase protection assay shows an altered cytokine and cytokine receptor profile in PDGF-B -/- chimeras. ApoE -/- mice were also treated for up to 50 weeks with a PDGF receptor antagonist that blocks all three PDGF receptor dimers. Blockade of the PDGF receptors similarly delays, but does not prevent, accumulation of smooth muscle and fibrous cap formation. Thus, elimination of PDGF-B from circulating cells or blockade of PDGF receptors does not appear sufficient to prevent smooth muscle accumulation in advanced lesions of atherosclerosis.

Identification of orally active, potent, and selective 4-piperazinylquinazolines as antagonists of the platelet-derived growth factor receptor tyrosine kinase family.

We have previously found that the 4-[4-(N-substituted carbamoyl)-1-piperazinyl]-6,7-dimethoxyquinazolines can function as potent and selective inhibitors of platelet-derived growth factor receptor (PDGFR) phosphorylation. A series of highly potent, specific, orally active, small molecule kinase inhibitors directed against members of PDGFR receptor have been developed through modifications of the novel quinazoline template I. Systematic modifications in the A-bicyclic ring and D-rings of protype I were carried out to afford potent analogues, which display IC(50) values of <250 nM in cellular betaPDGFR phosphorylation assays. An optimized analogue in this series, 75 (CT53518), inhibits Flt-3, betaPDGFR, and c-Kit receptor phosphorylation with IC(50) values of 50-200 nM, whereas 15-20-fold less potent activity against CSF-1R was observed. This analogue also inhibits autophosphorylation of Flt-3 ligand-stimulated wild-type Flt-3 and a constitutively activated Flt-3/internal tandem duplication (ITD) with IC(50) values of 30-100 nM. Through this optimization process, 75 was found to be metabolically stable and has desirable pharmacokinetic properties in all animal species studied (F% > 50%, T(1/2) > 8 h). Oral administration of 75 promotes mice survival and significantly delayed disease progression in a Flt-3/ITD-mediated leukemia mouse model and shows efficacy in a nude mouse model of chronic myelomonocytic leukemia.

CT53518, a novel selective FLT3 antagonist for the treatment of acute myelogenous leukemia (AML).

Up to 30% of acute myelogenous leukemia (AML) patients harbor an activating internal tandem duplication (ITD) within the juxtamembrane domain of the FLT3 receptor, suggesting that it may be a target for kinase inhibitor therapy. For this purpose we have developed CT53518, a potent antagonist that inhibits FLT3, platelet-derived growth factor receptor (PDGFR), and c-Kit (IC(50) approximately 200 nM), while other tyrosine or serine/threonine kinases were not significantly inhibited. In Ba/F3 cells expressing different FLT3-ITD mutants, CT53518 inhibited IL-3-independent cell growth and FLT3-ITD autophosphorylation with an IC(50) of 10-100 nM. In human FLT3-ITD-positive AML cell lines, CT53518 induced apoptosis and inhibited FLT3-ITD phosphorylation, cellular proliferation, and signaling through the MAP kinase and PI3 kinase pathways. Therapeutic efficacy of CT53518 was demonstrated both in a nude mouse model and in a murine bone marrow transplant model of FLT3-ITD-induced disease.