Dengue Virus Glycosylation: What Do We Know?

In many infectious diseases caused by either viruses or bacteria, pathogen glycoproteins play important roles during the infection cycle, ranging from entry to successful intracellular replication and host immune evasion. Dengue is no exception. Dengue virus glycoproteins, envelope protein (E) and non-structural protein 1 (NS1) are two popular sub-unit vaccine candidates. E protein on the virion surface is the major target of neutralizing antibodies. NS1 which is secreted during DENV infection has been shown to induce a variety of host responses through its binding to several host factors. However, despite their critical role in disease and protection, the glycosylated variants of these two proteins and their biological importance have remained understudied. In this review, we seek to provide a comprehensive summary of the current knowledge on protein glycosylation in DENV, and its role in virus biogenesis, host cell receptor interaction and disease pathogenesis.

Examining pediatric emergency home ventilation practices in home health nurses: Opportunities for improved care.

OBJECTIVES: To assess the pediatric home health nurses' knowledge in tracheostomy and ventilator emergency care on home mechanical ventilation (HMV). BACKGROUND: Emergencies are frightening experiences for solo home health nurses and require advanced skills in emergency response and care, especially in pediatric patients who pose unique challenges. WORKING HYPOTHESIS: Nurses with greater years of nursing experience would perform better on emergency HMV case-based scenarios than nurses with less years of experience. STUDY DESIGN: An exploratory online survey was used to evaluate emergency case-based pediatric scenarios. Demographic and professional experiences were profiled. PATIENT-SUBJECT SELECTION: Seventy-nine nurses had an average of 6.73 (SD = 1.41) years in pediatric nursing. Over 70% received their HMV training in their agency, 41% had less than 4 years of experience, and 30.4% had encountered at least one emergency situation at home. METHODOLOGY: The online survey was distributed by managers of 22 home health agencies to nurses providing pediatric HMV care. RESULTS: Nurses scored an average of 4.87 out of 10 possible points. There were no significant differences between nurses with <4 years of experience versus those with more experience on ventilator alarms knowledge or total knowledge. Ninety-seven percent of the nurses favored more training in HMV from a variety of settings (e.g., agency, on-line training). CONCLUSIONS: Nurses did not perform well in case-based ventilator alarm scenarios. Length of nursing experience did not differentiate greater knowledge. It is clear that nurses require and want more training in emergency-based HMV. Recommendations for an enhanced curriculum are suggested.

Inhibition of neuronal nitric oxide synthase activity promotes migration of human-induced pluripotent stem cell-derived neural stem cells toward cancer cells.

The breakthrough in derivation of human-induced pluripotent stem cells (hiPSCs) provides an approach that may help overcome ethical and allergenic challenges posed in numerous medical applications involving human cells, including neural stem/progenitor cells (NSCs). Considering the great potential of NSCs in targeted cancer gene therapy, we investigated in this study the tumor tropism of hiPSC-derived NSCs and attempted to enhance the tropism by manipulation of biological activities of proteins that are involved in regulating the migration of NSCs toward cancer cells. We first demonstrated that hiPSC-NSCs displayed tropism for both glioblastoma cells and breast cancer cells in vitro and in vivo. We then compared gene expression profiles between migratory and non-migratory hiPSC-NSCs toward these cancer cells and observed that the gene encoding neuronal nitric oxide synthase (nNOS) was down-regulated in migratory hiPSC-NSCs. Using nNOS inhibitors and nNOS siRNAs, we demonstrated that this protein is a relevant regulator in controlling migration of hiPSC-NSCs toward cancer cells, and that inhibition of its activity or down-regulation of its expression can sensitize poorly migratory NSCs and be used to improve their tumor tropism. These findings suggest a novel application of nNOS inhibitors in neural stem cell-mediated cancer therapy.

Polyethylenimine coating to produce serum-resistant baculoviral vectors for in vivo gene delivery.

Recombinant baculoviral vectors efficiently transduce many types of mammalian cells. However, their in vivo applications are hampered by the sensitivity of the virus to complement-mediated inactivation. Based on our observation that the surface charge of baculovirus is negative at neutral pH, we developed a procedure to coat baculoviral vectors with positively charged polyethylenimine 25 kDa, a commonly tested non-viral gene delivery vector, through electrostatic interaction. This coating was effective in protecting baculoviral vectors against human and rat serum-mediated inactivation in vitro, providing transduction efficiencies comparable with that generated by the control virus used under a serum-free condition. Enhanced in vivo gene expression in the liver and spleen was observed after tail vein injection of the coated viruses into mice. When injected directly into human tumor xenografts in nude mice, the coated viruses suppressed tumor development more effectively than uncoated viral vectors. These findings demonstrated the usefulness of using a simple coating method to circumvent a major obstacle to in vivo application of baculoviral vectors. The method may also serve as a flexible platform technology for improved use of the vectors, for example introducing a targeting ligand and minimizing immune responses.

Origins of medial geniculate body projections to physiologically defined zones of rat primary auditory cortex.

Medial geniculate body neurons projecting to physiologically identified subregions of rat primary auditory cortex (area 41, Te1) were labeled with horseradish peroxidase in adult rats. The goals were to determine the type(s) of projection neuron and the spatial arrangement of these cells with respect to thalamic subdivisions. Maps of best frequency were made with single neuron or unit cluster extracellular recording at depths of 500-800 microm, which correspond to layers III-IV in Nissl preparations. Tracer injections were made in different cortical isofrequency regions (2, 11, 22, or 38 kHz, respectively). Labeled neurons were plotted on representative sections upon which the architectonic subdivisions were drawn independently. Most of the cells of origin lay in the ventral division in every experiment. Injections at low frequencies labeled bands of neurons laterally in the ventral division; progressively more rostral deposits at higher frequencies labeled bands or clusters more medially in the ventral division, and through most of its caudo-rostral extent. Medial division labeling was variable. Labeled cells were always in the lateral half of the nucleus and were often scattered. There were few labeled cells in the dorsal division. Seven types of thalamocortical neuron were identified: ventral division cells had a tufted branching pattern, while medial division neurons have heterogeneous shapes and sizes and were larger. Dorsal division neurons had a radiate branching pattern. The size range of labeled neurons spanned that of Nissl stained neuronal somata. Area 41 may receive two types of thalamic projection: ventral division input is strongly convergent, highly topographic, spatially focal, and restricted to one type of neuron only, while the medial division projection is more divergent, coarsely topographical, involves multiple cortical areas, and has several varieties of projection neuron. Despite species differences in local circuitry, many facets of thalamocortical organization are conserved in phylogeny.

Effects of superior olivary complex lesions on binaural responses in rat auditory cortex.

Unilateral or bilateral lesions of the superior olivary complex (SOC) were made by local injection of kainic acid through a micropipette lowered stereotaxically into the rat's auditory brain stem. The lesions had the effect of destroying cell bodies in the superior olive without disrupting fibers of passage. After a recovery period of approximately one month physiological recordings were made with tungsten microelectrodes from the auditory cortex of normal animals and animals with SOC lesions. For animals with unilateral SOC lesions recordings were made either ipsilateral or contralateral to the site of damage. Monaural and binaural tone bursts (110 ms duration) were presented dichotically through a sealed sound delivery system and binaural interaction patterns were determined by comparison of monaural and binaural responses. Some cells were excited by stimulation of either ear and facilitated by binaural stimulation (binaural summation or EE cells), whereas others were excited by contralateral stimulation and inhibited by simultaneous ipsilateral stimulation (binaural suppression or EI cells). Both binaural summation and suppression responses were still present following unilateral SOC lesions. Interaural intensity difference thresholds were within the normal range and no differences were found between animals with lesions placed ipsilateral or contralateral to the recording site. Following a bilateral lesion in one case, both binaural summation and suppression responses were still present. The bilateral lesion had the effect of shifting the average interaural intensity difference thresholds in favor of the contralateral ear. These data suggest that binaural interactions above the level of the superior olive contribute to physiological responses in auditory cortex and that binaural responses in the rat's auditory cortex are shaped by both olivary and supraolivary interactions.

Effects of superior olivary complex lesions on binaural responses in rat inferior colliculus.

Unilateral or bilateral lesions of the superior olivary complex (SOC) were made by local injection of kainic acid through a micropipette lowered stereotaxically into the rat's auditory brainstem. The lesions had the effect of destroying cell bodies in the superior olive without disrupting fibers of passage. After a recovery period of approximately one month, physiological recordings were made with tungsten micro-electrodes from the central nucleus of the inferior colliculus of animals with SOC lesions. For animals with unilateral lesions recordings were made either ipsilateral or contralateral to the site of damage. Results were compared with data from normal control cases. Monaural and binaural tone bursts were presented through a sealed sound delivery system and binaural interaction patterns were determined. Both binaural summation and suppression responses were still present following unilateral SOC lesions. Interaural intensity difference thresholds were within the normal range and no differences were found between animals with lesions placed ipsilateral or contralateral to the recording site. Binaural summation and suppression responses were also present following bilateral lesions. Bilateral lesions had the effect of shifting the average interaural intensity difference thresholds in favor of the contralateral ear. But, in general, binaural interactions were remarkably little affected by bilateral destruction of the SOC.

Organization of auditory cortex in the albino rat: binaural response properties.

1. The binaural response properties of neurons in the auditory cortex of the albino rat were examined using microelectrode mapping techniques. Characteristic frequencies, binaural response classes, and interaural intensity differences for binaural interaction were determined for multiple electrode penetrations across the cortical surface. The location of electrode penetrations was determined by reference to the cortical vascular pattern in individual animals. 2. When examined over a wide range of interaural intensities binaural responses could be classified as one of the following types: summation, i.e., excited by stimulation of either ear alone and facilitated by stimulation of both ears together (35.3%); suppression, i.e., excited by contralateral stimulation, unaffected by ipsilateral stimulation alone, but inhibited under binaural stimulus conditions (42.2%); mixed, i.e., facilitated by binaural stimulation at near threshold levels, but strongly inhibited by increased sound pressure levels in the ipsilateral ear (18.5%); or other, i.e., responses that could not be classified as any other type (4%). 3. Neurons of the summation and suppression class often exhibited binaural interaction when the intensities at both ears were approximately equal. The modal interaural intensity difference for both response types was between 0 and +5 dB. Neurons of the mixed interaction class were facilitate at near equal dichotic intensity but suppressed when the intensity in the ipsilateral ear was increased. The modal value was between 0 and +5 dB for summation and +20 dB for suppression. 4. Summation, suppression, and mixed binaural response types were found over a wide range of sound frequencies from 1 to 40 kHz. There was some tendency for summation responses to prevail at lower frequencies and suppression responses to prevail at higher frequencies but the differences were not large. Generally, responses from each of the three binaural classes were well represented over the rat's hearing range. 5. Cells of the same binaural response type were grouped together to form aggregates of summation, suppression, or mixed interaction patterns. Cortical areas with similar binaural response properties appeared in some cases to extend across isofrequency contours.

Organization of auditory cortex in the albino rat: sound frequency.

1. Responses of neurons in the auditory cortex of the albino rat were examined using microelectrode mapping techniques. Characteristic frequencies were determined for numerous electrode penetrations across the cortical surface in individual animals. A primary auditory area was identified in the posterolateral neocortex that was characterized by short latency responses to tone bursts and tonotopic organization with high frequencies represented rostrally and low frequencies, caudally. Within this area cells with similar characteristic frequencies were aligned in a dorsoventral orientation to form isofrequency contours. 2. Tuning curves obtained from primary auditory cortex were characteristically "V" shaped with Q10's ranging from 0.97 to 28.4. Maximum Q10 values increased monotonically with characteristic frequency (CF). The lowest thresholds at CF closely approximated the behavioral audiogram for the albino rat. Many neurons, however, had CF thresholds well above the behavioral limit. 3. Areas were found dorsal and ventral to the primary auditory cortex in which CF's were clearly discontinuous with the neighboring isofrequency contours. These data suggest the presence of other auditory fields, the detailed characteristics of which have yet to be examined.