Circadian control of hepatitis B virus replication

Chronic hepatitis B virus (HBV) infection is a major cause of liver disease and cancer worldwide for which there are no curative therapies. The major challenge in curing infection is eradicating or silencing the covalent closed circular DNA (cccDNA) form of the viral genome. The circadian factors BMAL1/CLOCK and REV-ERB are master regulators of the liver transcriptome and yet their role in HBV replication is unknown. We establish a circadian cycling liver cell-model and demonstrate that REV-ERB directly regulates NTCP-dependent hepatitis B and delta virus particle entry. Importantly, we show that pharmacological activation of REV-ERB inhibits HBV infection in vitro and in human liver chimeric mice. We uncover a role for BMAL1 to bind HBV genomes and increase viral promoter activity. Pharmacological inhibition of BMAL1 through REV-ERB ligands reduces pre-genomic RNA and de novo particle secretion. The presence of conserved E-box motifs among members of the Hepadnaviridae family highlight an evolutionarily conserved role for BMAL1 in regulating this family of small DNA viruses.

Numerical study on electrohydrodynamic multiple droplet interactions

We present a numerical study of inviscid multiple droplet coalescence and break-up under the action of electric forces. Using an embedded potential flow model for the droplet hydrodynamics, coupled with an unbounded exterior electrostatic problem, we are able to perform computations through various singular events and analyze the effects of the electrical field intensity on droplet interactions. Laboratory experiments on the electrodynamics of droplet pairs show a much richer, and sometimes unexpected, behavior than that of isolated droplets. For example, it has been found that opposite charged droplets tend to repel each other when the electric field intensity is above a certain critical value. Although the mathematical model employed in this work incorporates very simple flow and electric assumptions, many of the droplet coalescence patterns seen in laboratory experiments can be reproduced. In this model, the interaction pattern of two droplets of radii R_{0} separated a distance D_{0}, depends on the ratio X_{0}=D_{0}/R_{0} and the applied uniform electric field intensity, E_{∞}. By performing a vast number of numerical simulations we are able to characterize the coalescence modes before and after drop merging as a function of these two parameters. The simulations predict that droplet repulsion occurs within a narrow interval of E_{∞} values, different for each X_{0}. Surprisingly, in this E_{∞} interval, a sharp transition between two power-law precoalescence flow regimes is seen. The evolution of several flow characteristics before and after coalescence, and the shape of the deformed droplets at coalescing time and the double cone angle, are also addressed and analyzed in detail. Cone angles below 35^{∘} lead to droplet coalescence for any X_{0} value, which is in accordance with previously reported studies. Finally, it is shown that the model and algorithm can handle multiple droplet interactions. The simulations qualitatively match results from water in oil experiments in microchannels, despite the fact that the exterior fluid is not considered in the mathematical model.

Electrohydrodynamic coalescence of droplets using an embedded potential flow model

The coalescence, and subsequent satellite formation, of two inviscid droplets is studied numerically. The initial drops are taken to be of equal and different sizes, and simulations have been carried out with and without the presence of an electrical field. The main computational challenge is the tracking of a free surface that changes topology. Coupling level set and boundary integral methods with an embedded potential flow model, we seamlessly compute through these singular events. As a consequence, the various coalescence modes that appear depending upon the relative ratio of the parent droplets can be studied. Computations of first stage pinch-off, second stage pinch-off, and complete engulfment are analyzed and compared to recent numerical studies and laboratory experiments. Specifically, we study the evolution of bridge radii and the related scaling laws, the minimum drop radii evolution from coalescence to satellite pinch-off, satellite sizes, and the upward stretching of the near cylindrical protrusion at the droplet top. Clear evidence of partial coalescence self-similarity is presented for parent droplet ratios between 1.66 and 4. This has been possible due to the fact that computational initial conditions only depend upon the mother droplet size, in contrast with laboratory experiments where the difficulty in establishing the same initial physical configuration is well known. The presence of electric forces changes the coalescence patterns, and it is possible to control the satellite droplet size by tuning the electrical field intensity. All of the numerical results are in very good agreement with recent laboratory experiments for water droplet coalescence.

[Regulation of the phases of the sleep-wakefulness cycle with histamine]

Distributed neural networks in the brain sustain generation of wakefulness and two sleep states: non-REM sleep and REM sleep. These three behavioral states are jointly ingrained in a rhythmic sequence that constitutes the sleep-wakefulness cycle. This paper reviews and updates knowledge about the involvement of the histaminergic system in sleep-wakefulness cycle organization. Histaminergic neurons are exclusively located in the hypothalamic tuberomammillary nucleus, but are the source of a widespread projection system to many brain regions. Histamine neurons are active during waking, especially with high attention need, and remain silent in both non-REM and REM sleep. There have been described four metabotropic histamine receptors, of which H1R, H2R and H3R are present in the nervous system. H1R and H2R are mainly postsynaptic heteroreceptors, whereas H3R is thought to be mostly a presynaptic auto- and hetero-receptor. Histaminergic neurons are excited by hypocretinergic neurons and most of the arousing hypocretin effects are thought to depend on histaminergic actions. Interactions among histaminergic axons and cholinergic nuclei within forebrain and brainstem are particularly important for cortical activation. In contrast, histaminergic tuberomammillary neurons, similarly to other aminergic neurons in locus coeruleus or dorsal raphe nucleus, are inhibited by non-REM sleep-promoting neurons of the preoptic region. Further inhibitory actions on histamine neurons come from adenosine release on tuberomammillary region. Finally, histaminergic neurons inhibit REM-on hypothalamic neurons containing melanine-concentrating hormone, thus supporting a permissive role of tuberomammillary nucleus in REM sleep. Actually, knockout mice for histidine decarboxylase, the enzyme synthetizing histamine, show a significant REM sleep increase.

Numerical simulations of electrostatically driven jets from nonviscous droplets

The evolution of a perfectly conducting and nonviscous fluid, under the action of an electric field (uniform at infinity), is studied numerically. Level set techniques are employed to develop an Eulerian potential flow model that can follow the drop evolution past breakup, while the free surface fluid velocity and the electric field force are obtained via axisymmetric boundary integral calculations. Numerical results are presented for neutral and charged droplets and for free charged droplets. In all cases, the evolution droplet aspect ratio, progeny droplet size, Taylor cone angles, jet shapes, and self-similar scaling exponents are reported. In particular, for free charged water droplets, the bursting frequency and other jetting characteristics have been carefully analyzed. Wherever possible, these results are compared with previously reported experiments and simulations.

Genotypes and phenotypes of 162 families with a glomulin mutation

A decade ago, we identified a novel gene, glomulin (GLMN) in which mutations cause glomuvenous malformations (GVMs). GVMs are bluish-purple cutaneous vascular lesions with characteristic glomus cells in the walls of distended venous channels. The discovery of the genetic basis for GVMs allowed the definition of clinical features to distinguish GVMs from other venous anomalies. The variation in phenotype was also highlighted: from a single punctate blue dot to a large plaque-like lesion. In this study, we screened GLMN in a large cohort of patients to broaden the spectrum of mutations, define their frequency and search for possible genotype-phenotype correlations. Taking into account 6 families published by others, a mutation in GLMN has been found in 162 families. This represents 40 different mutations; the most frequent one being present in almost 45% of them. Expressivity varies largely, without a genotype/phenotype relationship. Among 381 individuals with a mutation, we discovered 37 unaffected carriers, implying a penetrance of 90%. As nonpenetrant individuals may transmit the disease to their descendants, knowledge on the mutational status is needed for appropriate genetic counseling.

Simulation of the droplet-to-bubble transition in a two-fluid system

Recent experiments by Burton and Taborek have demonstrated a droplet-to-bubble transition in the pinchoff behavior of one inviscid fluid inside another. With D the relative densities ρ(E)/ρ(ℑ), they find transition from (D=0) droplet-to-bubble behavior at D≈4. Numerical simulations of this two-fluid system, up to and beyond the initial breakup of the inner fluid, have been carried out utilizing level set and boundary integral methods. A droplet-to-bubble transition is predicted: For D sufficiently large, the volume of the satellite droplet shrinks to zero and there is no overturning of the fluid at separation. The calculated self-similar scaling exponents and the pinchoff region shapes match the known behavior at the droplet and bubble extremes (D=0, D=100). For intermediate D values, the simulations presented here indicate that the transition range between droplet and bubble behavior depends upon initial drop geometry. When the neck separates two nonequal inner fluid masses the transition is mild and occurs in the range 4<D<10, whereas in the case of equal masses an abrupt transition occurs at D≈4 in perfect agreement with the above mentioned experiments.

A prospective study of PHACE syndrome in infantile hemangiomas: demographic features, clinical findings, and complications

PHACE (OMIM no. 606519) is a neurocutaneous syndrome that refers to the association of large, plaque-like, "segmental" hemangiomas of the face, with one or more of the following anomalies: posterior fossa brain malformations, arterial cerebrovascular anomalies, cardiovascular anomalies, eye anomalies, and ventral developmental defects, specifically sternal defects and/or supraumbilical raphe. The etiology and pathogenesis of PHACE is unknown, and potential risk factors for the syndrome have not been systematically studied. The purpose of this study was thus to determine (1) the incidence of PHACE and associated anomalies among a large cohort of hemangioma patients, (2) whether certain demographic, prenatal or perinatal risk factors predispose infants to this syndrome, and (3) whether the cutaneous distribution of the hemangioma can be correlated to the types of anomalies present. We undertook a prospective, cohort study of 1,096 children with hemangiomas, 25 of whom met criteria for PHACE. These 25 patients represented 20% of infants with segmental facial hemangiomas. Compared to previous reports, our PHACE patients had a higher incidence of cerebrovascular and cardiovascular anomalies. Two developed acute arterial ischemic stroke during infancy, while two with cardiovascular anomalies showed documented evidence of normalization, suggesting that both progressive and regressive vascular phenomena may occur in this syndrome. Correlation to the anatomic location of the hemangioma appears to be helpful in determining which structural abnormalities might be present. A comparison of demographic and perinatal data between our PHACE cases and the hemangioma cohort overall showed no major differences, except a trend for PHACE infants to be of slighter higher gestational age and born to slightly older mothers. Eighty-eight percent were female, a finding which has been noted in multiple other reports. Further research is needed to determine possible etiologies, optimal evaluation, and outcomes.

Congenital myopathy, recurrent secretory diarrhea, bullous eruption of skin, microcephaly, and deafness: a new genetic syndrome?

We describe three siblings with congenital myopathy, bullous eruption of the skin, secretory diarrhea, apparent zinc deficiency, failure to thrive, deafness, and microcephaly. The parents are not consanguineous and there are no other affected relatives. This new syndrome, which follows an apparent autosomal recessive pattern, appears to be distinct from known syndromes of secretory diarrhea, myopathy, deafness, microcephaly, and zinc deficiency.

Effective therapy of a vascular tumor of infancy with vincristine

Vascular tumors are common in infancy, affecting as many as 10% of children. These lesions often follow a benign course, with an initial proliferative phase followed by spontaneous involution, and require no therapy. Others manifest explosive early growth and Kasabach-Merritt phenomenon, requiring therapeutic intervention. Occasionally, some bulky tumors threaten life or vision because of mass effect, also mandating intervention. Steroids are the mainstay of therapy, but often are ineffective. Interferon alpha (2a and 2b) has been used as second-line therapy in cases of steroid failure. However, interferon therapy has been associated with a significant incidence of spastic diplegia. The authors present the case of a 3-month-old girl in whom respiratory distress secondary to tracheal compression developed. Magnetic resonance imaging and magnetic resonance angiography showed a large cervicothoracic lesion encasing the great vessels and displacing the airway. She did not display associated Kasabach-Merritt phenomenon. The lesion proved refractory to standard steroid therapy, but responded dramatically to 4 cycles of vincristine (0.05 mg/kg). Although this agent has been used in children with life-threatening Kasabach-Merritt phenomenon, this is the first time it has been described in the setting of compromised vital function. Vinca alkaloids recently have been shown to have potent antiangiogenic activities in experimental models. Given the low predicted incidence of side effects at this dose, vincristine used as an antiangiogenic agent may prove an attractive alternative therapy for patients with life-threatening vascular tumors of infancy.

Epidermolysis bullosa with congenital pyloric atresia: novel mutations in the beta 4 integrin gene (ITGB4) and genotype/phenotype correlations

Epidermolysis bullosa with pyloric atresia (EB-PA: OMIM 226730), also known as Carmi syndrome, is a rare autosomal recessive genodermatosis that manifests with neonatal mucocutaneous fragility associated with congenital pyloric atresia. The disease is frequently lethal within the first year, but nonlethal cases have been reported. Mutations in the genes encoding subunit polypeptides of the alpha 6 beta 4 integrin (ITGA6 and ITGB4) have been demonstrated in EB-PA patients. To extend the repertoire of mutations and to identify genotype-phenotype correlations, we examined seven new EB-PA families, four with lethal and three with nonlethal disease variants. DNA from patients was screened for mutations using heteroduplex analysis followed by nucleotide sequencing of PCR products spanning all beta 4 integrin-coding sequences. Mutation analysis disclosed 12 distinct mutations, 11 of them novel. Four mutations predicted a premature termination codon as a result of nonsense mutations or small out-of-frame insertions or deletions, whereas seven were missense mutations. This brings the total number of distinct ITGB4 mutations to 33. The mutation database indicates that premature termination codons are associated predominantly with the lethal EB-PA variants, whereas missense mutations are more prevalent in nonlethal forms. However, the consequences of the missense mutations are position dependent, and substitutions of highly conserved amino acids may have lethal consequences. In general, indirect immunofluorescence studies of affected skin revealed negative staining for beta 4 integrin in lethal cases and positive, but attenuated, staining in nonlethal cases and correlated with clinical phenotype. The data on specific mutations in EB-PA patients allows prenatal testing and preimplantation genetic diagnosis in families at risk.

Hemangiomas: update on classification, clinical presentation, and associated anomalies

Infantile hemangiomas occur in 10% of children and are 3 times more common in female infants. The majority of hemangiomas are small, superficial tumors that require little, if any, treatment. During the last several years, new information regarding the classification, presentation, associations, and differential diagnosis of hemangioma has emerged and altered the management of these tumors. The purpose of this article is to briefly review some of these clinically relevant findings. A discussion of the pathogenesis and management of these potentially problematic tumors is beyond the scope of this article, but these topics have been addressed in several excellent reviews.

Epidermolytic hyperkeratosis in a Hispanic family resulting from a mutation in the keratin 1 gene

Epidermolytic hyperkeratosis (EHK; bullous congenital ichthyosiform erythroderma) is a genodermatosis resulting from mutations in either the keratin 1 (K1) or keratin 10 (K10) genes. It is characterized by erythroderma and blistering at birth, and the development of ichthyotic hyperkeratosis and palmoplantar keratoderma. A wide variety of mutations within the highly conserved helix initiation and termination motifs of the central rod domains of the K1 or K10 genes correlate with the highly variable phenotypic severity observed in EHK. We report a novel missense mutation designated L214P in a large Hispanic pedigree with EHK. The mutation is located in the highly conserved 1A segment of the alpha-helical rod domain. The presence of this mutation underscores the importance of sequence alterations located in the central rod domain in the pathogenesis of EHK.

Novel ITGB4 mutations in lethal and nonlethal variants of epidermolysis bullosa with pyloric atresia: missense versus nonsense

Epidermolysis bullosa with pyloric atresia (EB-PA), an autosomal recessive genodermatosis, manifests with neonatal cutaneous blistering associated with congenital pyloric atresia. The disease is frequently lethal, but nonlethal cases have also been reported. Expression of the alpha6 beta4 integrin is altered at the dermal-epidermal basement-membrane zone; recently, mutations in the corresponding genes (ITGA6 and ITGB4) have been disclosed in a limited number of patients, premature termination codons in both alleles being characteristic of lethal variants. In this study, we have examined the molecular basis of EB-PA in five families, two of them with lethal and three of them with nonlethal variants of the disease. Mutation analysis disclosed novel lesions in both ITGB4 alleles of each proband. One of the patients with lethal EB-PA was a compound heterozygote for premature termination-codon mutations (C738X/4791delCA), whereas the other patient with a lethal variant was homozygous for a missense mutation involving a cysteine residue (C61Y). The three nonlethal cases had missense mutations in both alleles (C562R/C562R, R1281W/R252C, and R1281W/R1281W). Immunofluorescence staining of skin in two of the nonlethal patients and in one of the lethal cases was positive, yet attenuated, for alpha6 and beta4 integrins. These results confirm that ITGB4 mutations underlie EB-PA and show that missense mutations may lead to nonlethal phenotypes.

Characterization of three human monoclonal antibodies specific for polymorphic class I and class II HLA antigens

Three human monoclonal antibodies were derived from a single polytransfused patient awaiting renal transplantation. In microcitotoxicity assays, the patient's serum displayed strong positive reactions against greater than 90% of a panel of cells representing the known HLA specificities. The donor's peripheral blood lymphocytes were infected with Epstein-Barr virus, cloned, and supernatants of the virus transformed cultures were screened for the presence of IgG antilymphocyte reactivity utilizing an enzyme-linked immunosorbent assay method. Positive cultures were recloned and fused with the human-mouse heteromyeloma SHM. Supernatants from three clones were selected for alloreactivity and characterized by indirect immunofluorescent staining and fluoroactivated cell sorter analysis on homozygous typing cells, including those from the Tenth International Histocompatibility Workshop core panel and on cell lines derived from selected families. Data obtained demonstrate that two human monoclonal antibodies have DQw1 specificity, one of them being reactive against several DQw7-positive cell lines, while one monoclonal antibody is specific for the A2 + A28 class I MHC antigens. Anti-DQw1 antibodies were of different light-chain subtypes.