The most severe sequelae after rehabilitation from SARS are femoral head necrosis and pulmonary fibrosis. We performed a 15-year follow-up on the lung and bone conditions of SARS patients. We evaluated the recovery from lung damage and femoral head necrosis in an observational cohort study of SARS patients using pulmonary CT scans, hip joint MRI examinations, pulmonary function tests and hip joint function questionnaires. Eighty medical staff contracted SARS in 2003. Two patients died of SARS, and 78 were enrolled in this study from August 2003 to March 2018. Seventy-one patients completed the 15-year follow-up. The percentage of pulmonary lesions on CT scans diminished from 2003 (9.40 ± 7.83)% to 2004 (3.20 ± 4.78)% (P < 0.001) and remained stable thereafter until 2018 (4.60 ± 6.37)%. Between 2006 and 2018, the proportion of patients with interstitial changes who had improved pulmonary function was lower than that of patients without lesions, as demonstrated by the one-second ratio (FEV 1 /FVC %, t = 2.21, P = 0.04) and mid-flow of maximum expiration (FEF 25%-75% , t = 2.76, P = 0.01). The volume of femoral head necrosis decreased significantly from 2003 (38.83 ± 21.01)% to 2005 (30.38 ± 20.23)% (P = 0.000 2), then declined slowly from 2005 to 2013 (28.99 ± 20.59)% and plateaued until 2018 (25.52 ± 15.51)%. Pulmonary interstitial damage and functional decline caused by SARS mostly recovered, with a greater extent of recovery within 2 years after rehabilitation. Femoral head necrosis induced by large doses of steroid pulse therapy in SARS patients was not progressive and was partially reversible.Bone Research (2020) 8:8; https://doi.

The extracellular aggregation of amyloid b (Ab) peptides and the intracellular hyperphosphorylation of tau at specific epitopes are pathological hallmarks of neurodegenerative diseases such as Alzheimer's disease (AD). Cdk5 phosphorylates tau at AD-specific phospho-epitopes when it associates with p25. p25 is a truncated activator, which is produced from the physiological Cdk5 activator p35 upon exposure to Ab peptides. We show that neuronal infections with Cdk5 inhibitory peptide (CIP) selectively inhibit p25/ Cdk5 activity and suppress the aberrant tau phosphorylation in cortical neurons. Furthermore, Ab 1À42 -induced apoptosis of these cortical neurons was also reduced by coinfection with CIP. Of particular importance is our finding that CIP did not inhibit endogenous or transfected p35/ Cdk5 activity, nor did it inhibit the other cyclin-dependent kinases such as Cdc2, Cdk2, Cdk4 and Cdk6. These results, therefore, provide a strategy to address, and possibly ameliorate, the pathology of neurodegenerative diseases that may be a consequence of aberrant p25 activation of Cdk5, without affecting 'normal' Cdk5 activity.

BackgroundThe novel coronavirus (SARS-CoV-2) infected over 3,300 health-care-workers (HCWs) in early 2020 in China. Little information is known about nosocomial infections of HCWs in the initial period. We analyzed data from HCWs with nosocomial infections in Wuhan Union Hospital and their family members. MethodsWe collected and analyzed data on exposure history, illness timelines, and epidemiologic characteristics of 25 laboratory-confirmed and two highly suspected HCWs as well as ten of their family members with COVID-19 from Jan 5 to Feb 12, 2020. Among them, demographics and clinical features of the 35 laboratory-confirmed cases were investigated and viral RNA of 12 cases was sequenced and analyzed. ResultsNine clusters were found among the patients. All patients showed mild to moderate clinical manifestation and recovered without deterioration. The average periods of incubation, clinical onset serial interval (COSI), and virus shedding were 4.5 days, 5.2 ± 3.2 days, and 18.5 days, respectively. Complete genomic sequences of 12 different coronavirus strains demonstrated that the viral structure with small, irrelevant mutations was stable in the transmission chains and showed remarkable traits of infectious traceability. ConclusionsSARS-CoV-2 can be rapidly transmitted person-to-person regardless of whether they have symptoms in both hospital settings and social activities based on the short period of incubation and COSI. The public health service should take practical measures to curb the spread, including isolation of cases, tracing close-contacts, and containment of severe epidemic areas. Besides, the HCWs should be alert during the epidemic, and make self-quarantine if self-suspected. Nosocomial Outbreak of 2019 Novel

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway plays an important role in mediating survival signals in wide variety of neurons and cells. Recent studies show that Akt also regulates metabolic pathways to regulate cell survival. In this study, we reported that cyclin-dependent kinase-5 (Cdk5) regulates Akt activity and cell survival through the neuregulin-mediated PI 3-kinase signaling pathway. We found that brain extracts of Cdk5؊/؊ mice display a lower PI 3-kinase activity and phosphorylation of Akt compared with that in wild type mice. Moreover, we demonstrated that Cdk5 phosphorylated Ser-1176 in the neuregulin receptor ErbB2 and phosphorylated Thr-871 and Ser-1120 in the ErbB3 receptor. We identified the Ser-1120 sequence RSRSPR in ErbB3 as a novel phosphorylation consensus sequence of Cdk5. Finally, we found that Cdk5 activity is involved in neuregulin-induced Akt activity and neuregulin-mediated neuronal survival. These findings suggest that Cdk5 may exert a key role in promoting neuronal survival by regulating Akt activity through the neuregulin/PI 3-kinase signaling pathway.Cyclin-dependent kinase 5 (Cdk5) 1 is a serine/threonine kinase, which is predominantly expressed in postmitotic neurons (1). Cdk5 kinase activity requires association with its neuronspecific activators, p35 and p39. Cdk5 kinase activity is essential for neuronal migration, neurite outgrowth, and laminar configuration of the cerebral cortex (2-4). Recently, Cdk5 has been suggested as contributing to the control of neuronal positioning in Reelin signaling during neural development (5) and to mediate neuronal guidance by regulating semaphorin-3A with Fyn kinase (6). Cdk5 and p35 have recently also been shown to regulate presynaptic and postsynaptic activity by phosphorylating Munc-18, amphiphysin, and the NR2A subunit of the N-methyl-D-aspartate receptor (7-11). Cdk5 activity also regulates dopamine signaling by phosphorylating DARPP-32 protein (12) and has been shown to up-regulate the expression of acetylcholine receptor at the neuromuscular junction (13). These studies indicate that Cdk5 is a multifunctional protein kinase in the central nervous system. Cdk5 has been implicated in both cell survival and programmed cell death in neuronal and nonneuronal systems (14,15). Cells induced to apoptosis by exogenous signals such as staurosporin display increased Cdk5 activity (16,17). Recently, Cdk5 in association with p25, a truncated form of p35, has been thought to be deregulated to produce hyperphosphorylated tau protein and to disrupt the neuronal cytoskeleton, and it may be involved in neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral secrosis, Parkinson's disease, and Niemann-Pick disease (18 -23). On the other hand, Cdk5 may also be involved in neuronal survival. Cdk5 knockout mice exhibit a unique phenotype with perinatal mortality, associated with extensively disrupted cerebral cortical layering due to abnormal neuronal migration, absence of cerebella foliation, and degeneration of neurons...

Glucocorticoids, major end effectors of the stress response, play an essential role in the homeostasis of the central nervous system and influence diverse functions of neuronal cells. We found that cyclin-dependent kinase 5 (CDK5), which plays important roles in the morphogenesis and functions of the nervous system and whose aberrant activation is associated with development of neurodegenerative disorders, interacted with the ligand-binding domain of the glucocorticoid receptor (GR) through its activator p35 or its active proteolytic fragment p25. CDK5 phosphorylated GR at multiple serines, including Ser203 and Ser211 of its N-terminal domain, and suppressed the transcriptional activity of this receptor on glucocorticoid-responsive promoters by attenuating attraction of transcriptional cofactors to DNA. In microarray analyses using rat cortical neuronal cells, the CDK5 inhibitor roscovitine differentially regulated the transcriptional activity of the GR on more than 90% of the endogenous glucocorticoid-responsive genes tested. Thus, CDK5 exerts some of its biological activities in neuronal cells through the GR, dynamically modulating GR transcriptional activity in a target promoter-dependent fashion.

The activity of Cdk5-p35 is tightly regulated in the developing and mature nervous system. Stress-induced cleavage of the activator p35 to p25 and a p10 N-terminal domain induces deregulated Cdk5 hyperactivity and perikaryal aggregations of hyperphosphorylated Tau and neurofilaments, pathogenic hallmarks in neurodegenerative diseases, such as Alzheimer disease and amyotrophic lateral sclerosis, respectively. Previously, we identified a 125-residue truncated fragment of p35 called CIP that effectively and specifically inhibited Cdk5-p25 activity and Tau hyperphosphorylation induced by A␤ peptides in vitro, in HEK293 cells, and in neuronal cells. Although these results offer a possible therapeutic approach to those neurodegenerative diseases assumed to derive from Cdk5-p25 hyperactivity and/or A␤ induced pathology, CIP is too large for successful therapeutic regimens. To identify a smaller, more effective peptide, in this study we prepared a 24-residue peptide, p5, spanning CIP residues Lys 245 -Ala 277 . p5 more effectively inhibited Cdk5-p25 activity than did CIP in vitro. In neuron cells, p5 inhibited deregulated Cdk5-p25 activity but had no effect on the activity of endogenous Cdk5-p35 or on any related endogenous cyclin-dependent kinases in HEK293 cells. Specificity of p5 inhibition in cortical neurons may depend on the p10 domain in p35, which is absent in p25. Furthermore, we have demonstrated that p5 reduced A␤(1-42)-induced Tau hyperphosphorylation and apoptosis in cortical neurons. These results suggest that p5 peptide may be a unique and useful candidate for therapeutic studies of certain neurodegenerative diseases.The activity of Cdk5, a multifunctional serine/threonine kinase, is critical for neuronal development and synaptic activity; it sustains neurite outgrowth, neuronal migration, cortical lamination, and survival (1-9). Its activity depends on the binding of its neuron-specific, cyclin-related activators, p35 and p39 (10, 11). Cdk5 has also been implicated as a key player in learning and memory (12-15).Normally, Cdk5 activity is tightly regulated, but under conditions of neuronal stress, it is deregulated, leading to hyperactivity, neuronal pathology, and cell death. Accordingly, Cdk5 has been implicated in certain neurodegenerative disorders, such as AD.2 A model of the role of Cdk5 in neurodegeneration suggests that a stress-induced influx of calcium ions into neurons activates calpain, a Ca 2ϩ -activated protease, which cleaves p35 into p25 and a p10 fragment. p25, in turn, forms a more stable Cdk5-p25 hyperactive complex, which hyperphosphorylates Tau and induces cell death (16 -21). Indeed, increased levels of p25 and Cdk5 activity have been reported in AD brains. The finding that p25 may be toxic comes from studies of cortical neurons treated with ␤-amyloid (A␤), a key marker of AD pathology, where p35 is converted to p25 accompanied by activated Cdk5, Tau hyperphosphorylation, and apoptosis (22,23).Expression of the Cdk5-p25 complex seems to be primarily responsible for the Tau pathology ...

Cdk5, a cyclin-dependent kinase, is critical for neuronal development, neuronal migration, cortical lamination, and survival. Its survival role is based, in part, on "cross-talk" interactions with apoptotic and survival signaling pathways. Previously, we showed that Cdk5 phosphorylation of mitogen-activated protein kinase kinase (MEK)1 inhibits transient activation induced by nerve growth factor (NGF) in PC12 cells. To further explore the nature of this inhibition, we studied the kinetics of NGF activation of extracellular signal-regulated kinase (Erk)1/2 in cortical neurons with or without roscovitine, an inhibitor of Cdk5. NGF alone induced an Erk1/2-transient activation that peaked in 15 min and declined rapidly to baseline. Roscovitine, alone or with NGF, reached peak Erk1/2 activation in 30 min that was sustained for 48 h. Moreover, the sustained Erk1/2 activation induced apoptosis in cortical neurons. Significantly, pharmacological application of the MEK1 inhibitor PD98095 to roscovitine-treated cortical neurons prevented apoptosis. These results were also confirmed by knocking down Cdk5 activity in cortical neurons with Cdk5 small interference RNA. Apoptosis was correlated with a significant shift of phosphorylated tau and neurofilaments from axons to neuronal cell bodies. These results suggest that survival of cortical neurons is also dependent on tight Cdk5 modulation of the mitogen-activated protein kinase signaling pathway. INTRODUCTIONSignal transduction cascades translate extracellular signals into cytoplasmic and nuclear compartments that control cell proliferation, differentiation, and survival in neurons as well as other cell types. The mitogen-activated protein kinase (MAPK) signaling network comprises a cascade of sequential kinase phosphorylations to elicit specific cellular behaviors. The duration of the activation determines the cellular response in neurons or neuron progenitors such as PC12 cells (Marshall, 1995;Stork, 2002). A transient extracellular signal-regulated kinase (Erk) activation (10 -20 min) as in epidermal growth factor activation of PC12 cells (Heasley and Johnson, 1992;Traverse et al., 1992) induces cell proliferation, a sustained activation (several hours) initiates neurite outgrowth and differentiation, whereas a more chronic activation of the Erk1/2 pathway (24 h), particularly in neurons under stress, is responsible for neuronal apoptosis (Subramaniam et al., 2003(Subramaniam et al., , 2004Cheung and Slack, 2004). Specific pharmacological inhibition of mitogen-activated protein kinase kinase (MEK)1, the upstream kinase from Erk1/2, prevents apoptosis (Alessandrini et al., 1997), which suggests that neuronal survival requires a precisely timed down-regulation of the activated Erk1/2 kinase. Timing depends, in part, on down-regulation of receptors, or feedback inhibition by phosphatases (Keyse, 2000), and/or cross-talk interactions with other signaling cascades. One of these crosstalk regulatory interactions may be exclusive to neurons, which, in contrast to most cells, po...

Cyclin-dependent kinase 5 (Cdk5) is predominantly expressed in the nervous system, where it is involved in neuronal migration, synaptic transmission, and survival. The role of Cdk5 in synaptic transmission is mediated by regulating the cellular functions of presynaptic proteins such as synapsin, Munc18, and dynamin 1. Its multifunctional role at the synapse is complex and probably involves other novel substrates. To explore this possibility, we used a yeast two-hybrid screen of a human cDNA library with p35 as bait and isolated human septin 5 (SEPT5), known also as hCDCrel-1, as an interacting clone. Here we report that p35 associates with SEPT5 in GST (glutathione S-transferase)-pull-down and coimmunoprecipitation assays. We confirmed that Cdk5/p35 phosphorylates SEPT5 in vitro and in vivo and identified S327 of SEPT5 as a major phosphorylation site. A serine (S)-to-alanine (A) 327 mutant of SEPT5 bound syntaxin more efficiently than SEPT5 wild type. Additionally, coimmunoprecipitation from synaptic vesicle fractions and Cdk5 wild-type and knock-out lysates showed that phosphorylation of septin 5 by Cdk5/p35 decreases its binding to syntaxin-1. Moreover, mutant nonphosphorylated SEPT5 potentiated regulated exocytosis more than the wild type when each was expressed in PC12 cells. These data suggest that Cdk5 phosphorylation of human septin SEPT5 at S327 plays a role in modulating exocytotic secretion.