Comorbidities and Late Outcomes in Neonatal Pulmonary Hypertension

Long-term outcomes of persistent pulmonary hypertension of newborn (PPHN) depend on disease severity, duration of ventilation, and associated anomalies. Congenital diaphragmatic hernia survivors may have respiratory morbidities and developmental delay. The presence of PPHN is associated with increased mortality in hypoxic-ischemic encephalopathy, though the effects on neurodevelopment are less clear. Preterm infants can develop pulmonary hypertension (PH) early in the postnatal course or later in the setting of bronchopulmonary dysplasia (BPD). BPD-PH is associated with higher mortality, particularly within the first year. Evidence suggests that both early and late PH in preterm infants are associated with neurodevelopmental impairment.

Origins and Proliferative States of Human Oligodendrocyte Precursor Cells

Human cerebral cortex size and complexity has increased greatly during evolution. While increased progenitor diversity and enhanced proliferative potential play important roles in human neurogenesis and gray matter expansion, the mechanisms of human oligodendrogenesis and white matter expansion remain largely unknown. Here, we identify EGFR-expressing "Pre-OPCs" that originate from outer radial glial cells (oRGs) and undergo mitotic somal translocation (MST) during division. oRG-derived Pre-OPCs provide an additional source of human cortical oligodendrocyte precursor cells (OPCs) and define a lineage trajectory. We further show that human OPCs undergo consecutive symmetric divisions to exponentially increase the progenitor pool size. Additionally, we find that the OPC-enriched gene, PCDH15, mediates daughter cell repulsion and facilitates proliferation. These findings indicate properties of OPC derivation, proliferation, and dispersion important for human white matter expansion and myelination.

The Impact of Telemedicine on Transfer Rates of Newborns at Rural Community Hospitals

BACKGROUND AND OBJECTIVE

Telemedicine may have the ability to reduce avoidable transfers by allowing remote specialists the opportunity to more effectively assess patients during consultations. In this study, we examined whether telemedicine consultations were associated with reduced transfer rates compared to telephone consultations among a cohort of term and late preterm newborns. We hypothesized that neonatologist consultations conducted over telemedicine would result in fewer interfacility transfers than consultations conducted over telephone.

METHODS

We collected data on all newborns who received a neonatal telemedicine or telephone consultation at 6 rural hospitals in northern and central California between August 2014 and June 2018. We used adjusted analyses to compare transfer rates between telemedicine and telephone cohorts.

RESULTS

A total of 317 patients were included in the analysis; 89 (28.1%) of these patients received a telemedicine consultation and 228 (71.9%) received a telephone consultation only. The overall transfer rate was 77.0%. Patient consultations conducted using telemedicine were significantly less likely to result in a transfer than patient consultations conducted using the telephone (64.0% vs 82.0%, P = .001). After controlling for 5-minute Apgar score, birthweight, gestational age, site of consultation, and Transport Risk Index of Physiologic Stability score, the odds of transfer for telemedicine consultations was 0.48 (95% confidence interval: 0.26, 0.90, P = .02).

CONCLUSIONS

Our findings suggest that telemedicine may have the potential to reduce potentially avoidable transfers of term and late preterm newborns. Future research on potentially avoidable transfers and patient outcomes is needed to better understand the ways in which telemedicine affects clinical decision-making.

Pbx3 is required for normal locomotion and dorsal horn development

The transcription cofactor Pbx3 is critical for the function of hindbrain circuits controlling respiration in mammals, but the perinatal lethality caused by constitutively null mutations has hampered investigation of other roles it may play in neural development and function. Here we report that the conditional loss of Pbx3 function in most tissues caudal to the hindbrain resulted in progressive deficits of posture, locomotion, and sensation that became apparent during adolescence. In adult mutants, the size of the dorsal horn of the spinal cord and the numbers of calbindin-, PKC-gamma, and calretinin-expressing neurons in laminae I-III were markedly reduced, but the ventral cord and peripheral nervous system appeared normal. In the embryonic dorsal horn, Pbx3 expression was restricted to a subset of glutamatergic neurons, but its absence did not affect the initial balance of excitatory and inhibitory interneuron phenotypes. By embryonic day 15 a subset of Meis(+) glutamatergic neurons assumed abnormally superficial positions and the number of calbindin(+) neurons was increased three-fold in the mutants. Loss of Pbx3 function thus leads to the incorrect specification of some glutamatergic neurons in the dorsal horn and alters the integration of peripheral sensation into the spinal circuitry regulating locomotion.

The role of iron and copper in the aetiology of neurodegenerative disorders: therapeutic implications

Abnormalities in the metabolism of the transition metals iron and copper have been demonstrated to play a crucial role in the pathogenesis of various neurodegenerative diseases. Metal homeostasis as it pertains to alterations in brain function in neurodegenerative diseases is reviewed in this article in depth. While there is documented evidence for alterations in the homeostasis, redox-activity and localisation of transition metals, it is also important to realise that alterations in specific copper- and iron-containing metalloenzymes appear to play a crucial role in the neurodegenerative process. These changes provide the opportunity to identify pathways where modification of the disease process can occur, potentially offering opportunities for clinical intervention. As understanding of disease aetiology evolves, so do the tools with which diseases are treated. In this article, we examine not only the possible mechanism of disease but also how pharmaceuticals may intervene, from direct and indirect antioxidant therapy to strategies involving gene therapy.

The state versus amyloid-beta: the trial of the most wanted criminal in Alzheimer disease

Investigators studying the primary culprit responsible for Alzheimer disease have, for the past two decades, primarily focused on amyloid-beta (Abeta). Here, we put Abeta on trial and review evidence amassed by the prosecution that implicate Abeta and also consider arguments and evidence gathered by the defense team who are convinced of the innocence of their client. As in all trials, the arguments provided by the prosecution and defense revolve around the same evidence, with opposing interpretations. Below, we present a brief synopsis of the trial for you, the jury, to decide the verdict. Amyloid-beta: guilty or not-guilty?

Amyloid-beta, tau alterations and mitochondrial dysfunction in Alzheimer disease: the chickens or the eggs?

Alzheimer disease (AD) is defined pathologically and diagnostically defined by amyloid-beta senile plaques and neurofibrillary tangles (NFT) composed of tau. From the time of their original description nearly a century ago, a major focus has been to understand the role that these lesions play in the pathogenesis of the disease. The majority favors the notion that these lesions cause the disease and therefore attempts at therapeutic intervention are focused on preventing lesions formation. However, this rationale may be misguided since new evidence from our laboratories and others suggest that the lesions not only occur as a by-product of the fundamental disease process but also that they may be protective.

Microtubule-associated protein 1B: a neuronal binding partner for myelin-associated glycoprotein

Myelin-associated glycoprotein (MAG) is expressed in periaxonal membranes of myelinating glia where it is believed to function in glia-axon interactions by binding to a component of the axolemma. Experiments involving Western blot overlay and coimmunoprecipitation demonstrated that MAG binds to a phosphorylated neuronal isoform of microtubule-associated protein 1B (MAP1B) expressed in dorsal root ganglion neurons (DRGNs) and axolemma-enriched fractions from myelinated axons of brain, but not to the isoform of MAP1B expressed by glial cells. The expression of some MAP1B as a neuronal plasma membrane glycoprotein (Tanner, S.L., R. Franzen, H. Jaffe, and R.H. Quarles. 2000. J. Neurochem. 75:553-562.), further documented here by its immunostaining without cell permeabilization, is consistent with it being a binding partner for MAG on the axonal surface. Binding sites for a MAG-Fc chimera on DRGNs colocalized with MAP1B on neuronal varicosities, and MAG and MAP1B also colocalized in the periaxonal region of myelinated axons. In addition, expression of the phosphorylated isoform of MAP1B was increased significantly when DRGNs were cocultured with MAG-transfected COS cells. The interaction of MAG with MAP1B is relevant to the known role of MAG in affecting the cytoskeletal structure and stability of myelinated axons.

Neurons in Alzheimer disease emerge from senescence

A number of cell cycle markers are associated with the selective neuronal pathology found in Alzheimer disease. However, the significance of such cell cycle markers is clouded by duplicity of function in that many such proteins are also involved in apoptosis and/or DNA repair following oxidative damage. To clarify whether or not neurons in Alzheimer disease do in fact emerge from a quiescent status, with subsequent entry into the G1 phase of the cell cycle, in this study we focused on a family of MORF4-related proteins that are associated with emergence from senescence. Our results show that many neurons in vulnerable regions of Alzheimer disease brain, but not in control brain, have increased MORF4-related proteins indicating re-entry into the cell cycle. Immunoblot analysis showed a specific disease-related increase in a 52 kDa protein that is likely the human homologue of the MORF4-related transcription factor. The novel localization of such a transcriptional activating protein to selectively vulnerable neurons in Alzheimer disease provides compelling evidence for mitotic re-entry as part of the pathogenesis of neuronal dysfunction and death in Alzheimer disease.

Activation of MKK6, an upstream activator of p38, in Alzheimer's disease

Mitogen-activated protein kinase (MAPK) p38 has been implicated in the pathogenesis of Alzheimer's disease, but the upstream cascade leading to p38 activation has not been elucidated in the disease. In the present study, we focused on mitogen-activated protein kinase kinase 6 (MKK6), one of the upstream activators of p38 MAPK. We found that MKK6 was not only increased but also specifically associated with granular structures in the susceptible neurons in the hippocampus and cortex of Alzheimer's disease patients, but was only weakly diffuse in the cytoplasm in neurons in control cases. Immunoblot analysis demonstrated a significant increase of MKK6 level in Alzheimer's disease compared with age-matched controls. In this regard, in hippocampal and cortical regions of individuals with Alzheimer's disease, the activated phospho-MKK6 was localized exclusively in association with pathological alterations including neurofibrillary tangles, senile plaques, neuropil threads and granular structures, overlapping with activated p38 MAPK suggesting both a functional and mechanic link. By immunoblot analysis, phospho-MKK6 is also significantly increased in AD compared with control cases. Together, these findings lend further credence to the notion that the p38 MAPK pathway is dysregulated in Alzheimer's disease and also indicates an active role for this pathway in disease pathogenesis.

Abortive apoptosis in Alzheimer's disease

Multiple studies suggest that neuronal death in Alzheimer's disease (AD) is the result of an apoptotic mechanism. However, the stereotypical manifestations that define the terminal phases of apoptosis, such as chromatin condensation, apoptotic bodies, and blebbing, are not seen in AD. In this study, we show that the caspases, such as caspase 6, which cleave amyloid-beta protein precursor (A beta PP) and presenilins, are localized to the pathological lesions associated with AD. However, while upstream caspases such as 8 and 9 are clearly found in association with the intraneuronal pathology in AD, downstream caspases such as 3, 6 and 7 are present only at control levels. Given that execution of apoptosis requires amplification of the caspase-mediated apoptotic signal, our results indicate that in AD there is a lack of effective apoptotic signal propagation to downstream caspase effectors. Therefore, while the presence of caspases, especially caspase 6, in association with extracellular deposits of amyloid-beta, could obviously have important ramifications on the proteolytic processing of A beta PP and, thereby, on disease pathogenesis, it seems that AD represents the first in vivo situation reported in which the initiation of apoptosis does not proceed to caspase-dependent cell death. This novel phenomenon of apoptotic avoidance, which we term abortive apoptosis, or abortosis, may represent an exit from the caspase-induced apoptotic program that leads to neuronal survival in AD.

Redox-active iron mediates amyloid-beta toxicity

While amyloid-beta toxicity is mediated by oxidative stress and can be attenuated by antioxidants, the actual biochemical mechanism underlying neurotoxicity remains to be established. However, since aggregated amyloid-beta can interact with transition metals, such as iron, both in vitro and in vivo, we suspected that bound iron might be the mediator of toxicity such that holo- and apo-amyloid would have differential effects on cellular viability. Here we demonstrate that when amyloid-beta is pretreated with the iron chelator deferoxamine, neuronal toxicity is significantly attenuated while conversely, incubation of holo-amyloid-beta with excess free iron restores toxicity to original levels. These data, taken together with the known sequelae of amyloid-beta, suggest that the toxicity of amyloid-beta is mediated, at least in part, via redox-active iron that precipitates lipid peroxidation and cellular oxidative stress.

Activation and redistribution of c-jun N-terminal kinase/stress activated protein kinase in degenerating neurons in Alzheimer's disease

Cellular responses to increased oxidative stress appear to be a mechanism that contributes to the varied cytopathology of Alzheimer's disease (AD). In this regard, we suspect that c-Jun N-terminal kinase/Stress activated protein kinase (JNK/SAPK), a major cellular stress response protein induced by oxidative stress, plays an important role in Alzheimer disease in susceptible neurons facing the dilemma of proliferation or death. We found that JNK2/SAPK-alpha and JNK3/SAPK-beta were related to neurofibrillary pathology and JNK1/SAP-Kgamma related to Hirano bodies in cases of AD but were only weakly diffuse in the cytoplasm in all neurons in control cases and in non-involved neurons in diseased brain. In this regard, in hippocampal and cortical regions of individuals with severe AD, the activated phospho-JNK/SAPK was localized exclusively in association with neurofibrillar alterations including neurofibrillary tangles, senile plaque neurites, neuropil threads and granulovacuolar degeneration structures (GVD), completely overlapping with tau-positive neurofibrillary pathology, but was virtually absent in these brain regions in younger and age-matched controls without pathology. However, in control patients with some pathology, as well as in mild AD cases, there was nuclear phospho-JNK/SAPK and translocation of phospho-JNK/SAPK from nuclei to cytoplasm, respectively, indicating that the activation and re-distribution of JNK/SAPK correlates with the progress of the disease. By immunoblot analysis, phospho-JNK/SAPK is significantly increased in AD over control cases. Together, these findings suggest that JNK/SAPK dysregulation, probably resulting from oxidative stress, plays an important role in the increased phosphorylation of cytoskeletal proteins found in AD.

Neuronal polo-like kinase in Alzheimer disease indicates cell cycle changes

Neurons of adults apparently lack the components necessary to complete the cell division process. Therefore, in Alzheimer disease, the increased expression of cell cycle-related proteins in degenerating neurons likely leads to an interrupted mitotic process associated with cytoskeletal abnormalities and, ultimately, neuronal degeneration. In this study, to further delineate the role of mitotic processes in the pathogenesis of Alzheimer disease, we undertook a study of polo-like kinase (Plk), a protein that plays a crucial role in the cell cycle. Our results show disease-related increases in Plk in susceptible hippocampal and cortical neurons in comparison to young or age-matched controls. An increase in neuronal Plk further implicates aberrations in cell cycle control in the pathogenesis of Alzheimer disease and provides a novel mechanistic basis for therapeutic intervention.

Neuronal CDK7 in hippocampus is related to aging and Alzheimer disease

Despite their supposedly terminally-differentiated quiescent status, many neurons in Alzheimer disease display an ectopic re-expression of cell-cycle related proteins. In the highly regulated process of cell cycle, cyclin-dependent kinase 7 (Cdk7) plays a crucial role as a Cdk-activating kinase and activates all of the major Cdk-cyclin substrates. In this study, we demonstrate that Cdk7 immunoreactivity is significantly elevated in susceptible hippocampal neurons of Alzheimer disease patients in comparison with age-matched controls. Notably, the expression of Cdk7 is age-dependent, with decreased levels between the ages of 54 and 65 years and after the age of 78. While the Cdk7 levels in Alzheimer disease patients are higher than controls within each age group, the difference is greatest between ages 54-65 where disease susceptibility and/or progression is likely more related to genetic factors.

Oxidative stress, antioxidants, and Alzheimer disease

Recent evidence in the field of Alzheimer disease research has highlighted the importance of oxidative processes in its pathogenesis. Examination of cellular changes shows that oxidative stress is an event that precedes the appearance of neurofibrillary tangles, one of the hallmark pathologies of the disease. Although it is still unclear what the initial source of the oxidative stress is in Alzheimer disease, it is likely that the process is highly dependent on the presence of redox-active transition metals, such as iron and copper. Because of the proximal role that oxidative stress mechanisms seem to play in the pathogenesis of Alzheimer disease, further investigation in this realm may lead to novel therapeutic strategies.

Activation of p38 kinase links tau phosphorylation, oxidative stress, and cell cycle-related events in Alzheimer disease

The temporal association between oxidative stress and the hallmark pathologies of Alzheimer disease (AD) demonstrates that oxidative stress is among the earliest events in the disease. Nonetheless, neither the consequences of oxidative stress nor how oxidative stress relates to other pathological features of the disease are clear at this point. To begin to address these issues, we investigated p38 kinase, which is induced by oxidative stress, in the pathogenesis of AD. In hippocampal and cortical brain regions of individuals with AD, p38 is exclusively localized in association with neurofibrillar pathology. By marked contrast, these brain regions exhibit a low level of diffuse p38 staining in the neuronal cytoplasm in controls. We found a complete overlap of the immunostaining profiles of p38 and tau-positive neurofibrillary pathology and that the majority of p38 was activated in AD neurons, both of which support an association of p38 with the disease process. Moreover, the finding that PHF-tau co-immunoprecipitates with p38, and that p38 co-purifies with PHF-tau, strongly suggests that they are physically associated in vivo. Since p38 is also implicated in cell cycle regulation, our findings provide a link between the cell cycle re-entrant phenotype, cytoskeletal phosphorylation and oxidative stress in AD.

Oxidative stress in Alzheimer's disease

Oxidative balance is emerging as an important issue in understanding the pathogenesis of Alzheimer's disease. Examination of Alzheimer's disease brain has demonstrated a great deal of oxidative damage, associated with both hallmark pathologies (senile plaques and neurofibrillary tangles) as well as in normal appearing pyramidal neurons. While this suggests that oxidative stress is a proximal event in Alzheimer's disease pathogenesis, the mechanisms by which redox balance is altered in the disease remains elusive. Determining which of the proposed sources of free radicals, which include mitochondrial dysfunction, amyloid-beta-mediated processes, transition metal accumulation and genetic factors like apolipoprotein E and presenilins, is responsible for redox imbalance will lead to a better understanding of Alzheimer's disease pathogenesis and novel therapeutic approaches.

Cyclin' toward dementia: cell cycle abnormalities and abortive oncogenesis in Alzheimer disease

Recent evidence has associated the aberrant, proximal re-expression of various cell cycle control elements with neuronal vulnerability in Alzheimer disease, a chronic neurodegeneration. Such ectopic localization of various cyclins, cyclin-dependent kinases, and cyclin inhibitors in neurons can be seen as an attempt to re-enter the cell cycle. Given that primary neurons are terminally differentiated, any attempted re-entry into the cell division cycle in this postmitotic environment will be dysregulated. Since successful dysregulation of the cell cycle is also the hallmark of a neoplasm, early cell-cycle pathophysiology in Alzheimer disease may recruit oncogenic signal transduction mechanisms and, hence, can be viewed as an abortive neoplastic transformation.