Recruitment and phosphorylation of SH2-containing inositol phosphatase and Shc to the B-cell Fc gamma immunoreceptor tyrosine-based inhibition motif peptide motif

Recently, we and others have demonstrated that negative signaling in B cells selectively induces the tyrosine phosphorylation of a novel inositol polyphosphate phosphatase, p145SHIP. In this study, we present data indicating that p145SHIP binds directly a phosphorylated motif, immunoreceptor tyrosine-based inhibition motif (ITIM), present in the cytoplasmic domain of Fc gammaRIIB1. Using recombinant SH2 domains, we show that binding is mediated via the Src homology region 2 (SH2)-containing inositol phosphatase (SHIP) SH2 domain. SHIP also bound to a phosphopeptide derived from CD22, raising the possibility that SHIP contributes to negative signaling by this receptor as well as Fc gammaRIIB1. The association of SHIP with the ITIM phosphopeptide was activation independent, while coassociation with Shc was activation dependent. Furthermore, experiments with Fc gammaRIIB1-deficient B cells demonstrated a genetic requirement for expression of Fc gammaRIIB1 in the induction of SHIP phosphorylation and its interaction with Shc. Based on these results, we propose a model of negative signaling in which co-cross-linking of surface immunoglobulin and Fc gammaRIIB1 results in sequential tyrosine phosphorylation of the ITIM, recruitment and phosphorylation of p145SHIP, and subsequent binding of Shc.

SARS-CoV-2 spike S1 subunit induces neuroinflammatory, microglial and behavioral sickness responses: Evidence of PAMP-like properties

SARS-CoV-2 infection produces neuroinflammation as well as neurological, cognitive (i.e., brain fog), and neuropsychiatric symptoms (e.g., depression, anxiety), which can persist for an extended period (6 months) after resolution of the infection. The neuroimmune mechanism(s) that produces SARS-CoV-2-induced neuroinflammation has not been characterized. Proposed mechanisms include peripheral cytokine signaling to the brain and/or direct viral infection of the CNS. Here, we explore the novel hypothesis that a structural protein (S1) derived from SARS-CoV-2 functions as a pathogen-associated molecular pattern (PAMP) to induce neuroinflammatory processes independent of viral infection. Prior evidence suggests that the S1 subunit of the SARS-CoV-2 spike protein is inflammatory in vitro and signals through the pattern recognition receptor TLR4. Therefore, we examined whether the S1 subunit is sufficient to drive 1) a behavioral sickness response, 2) a neuroinflammatory response, 3) direct activation of microglia in vitro, and 4) activation of transgenic human TLR2 and TLR4 HEK293 cells. Adult male Sprague-Dawley rats were injected intra-cisterna magna (ICM) with vehicle or S1. In-cage behavioral monitoring (8 h post-ICM) demonstrated that S1 reduced several behaviors, including total activity, self-grooming, and wall-rearing. S1 also increased social avoidance in the juvenile social exploration test (24 h post-ICM). S1 increased and/or modulated neuroimmune gene expression (Iba1, Cd11b, MhcIIα, Cd200r1, Gfap, Tlr2, Tlr4, Nlrp3, Il1b, Hmgb1) and protein levels (IFNγ, IL-1β, TNF, CXCL1, IL-2, IL-10), which varied across brain regions (hypothalamus, hippocampus, and frontal cortex) and time (24 h and 7d) post-S1 treatment. Direct exposure of microglia to S1 resulted in increased gene expression (Il1b, Il6, Tnf, Nlrp3) and protein levels (IL-1β, IL-6, TNF, CXCL1, IL-10). S1 also activated TLR2 and TLR4 receptor signaling in HEK293 transgenic cells. Taken together, these findings suggest that structural proteins derived from SARS-CoV-2 might function independently as PAMPs to induce neuroinflammatory processes via pattern recognition receptor engagement.

Negative signaling in B cells: SHIP Grbs Shc

Negative signaling in B cells is initiated by co-crosslinking of the antigen receptor and the Fcy receptor, resulting in cessation of B-cell signaling events and, in turn, inhibiting B-cell proliferation and antibody secretion. Here, a competitive role is proposed for SHIP in blocking the interaction of Shc with the Grb2-Sos complex of proteins that lead to Ras activation in B cells.

FcgammaRIIb modulation of surface immunoglobulin-induced Akt activation in murine B cells

We examined activation of the serine/threonine kinase Akt in the murine B cell line A20. Akt is activated in a phosphoinositide 3-kinase (PtdIns 3-kinase)-dependent manner upon stimulation of the antigen receptor, surface immunoglobulin (sIg). In contrast, Akt induction is reduced upon co-clustering of sIg with the B cell IgG receptor, FcgammaRIIb. Co-clustering of sIg-FcgammaRIIb transmits a dominant negative signal and is associated with reduced accumulation of the PtdIns 3-kinase product phosphatidylinositol 3,4,5-trisphosphate (PtdIns 3,4,5-P3), known to be a potent activator of Akt. PtdIns 3-kinase is activated to the same extent with and without FcgammaRIIb co-ligation, indicating conditions supporting the generation of PtdIns 3,4,5-P3. We hypothesized that the decreased Akt activity arises from the consumption of PtdIns 3,4,5-P3 by the inositol-5-phosphatase Src homology 2-containing inositol 5-phosphatase (SHIP), which has been shown by us to be tyrosine-phosphorylated and associated with FcgammaRIIb when the latter is co-ligated. In direct support of this hypothesis, we report here that Akt induction is greatly reduced in fibroblasts expressing catalytically active but not inactive SHIP. Likewise, the reduction in Akt activity upon sIg-FcgammaRIIb co-clustering is absent from avian B cells lacking expression of SHIP. These findings indicate that SHIP acts as a negative regulator of Akt activation.

The role of nitric oxide synthase/nitric oxide in vascular smooth muscle control

Vascular compliance is dependent on endogenous and exogenous sources of nitric oxide (NO). In a discussion of therapeutics and NO derived via nitric oxide synthase (NOS) enzymes, it is necessary to examine the pathways of each drug to provide the clinical perfusionist with a greater understanding of the role of NOS/NO in vascular function. Endothelial-derived NO is a contributor in the vasoregulation of vascular smooth muscle. Therapeutics seek to mimic the vasodilatory effects of the endogenous NO. The therapeutics included in this review are nitroglycerin, nitroprusside, amyl nitrite, and inhalation of NO. L-Arginine supplementation provides additional substrate for the endogenous pathway that can augment NO production. NO is a small bioactive molecule involved in various biochemical pathways. Dysregulation of NO production can impair normal physiologic control of vascular compliance. Therefore, the purpose of this review is to provide the perfusionist with an understanding of the biochemical and pharmacological aspects of NOS/NO associated with vascular function.

Characterization of exopolymers of aquatic bacteria by pyrolysis-mass spectrometry

Exopolymers from a diverse collection of marine and freshwater bacteria were characterized by pyrolysis-mass spectrometry (Py-MS). Py-MS provides spectra of pyrolysis fragments that are characteristic of the original material. Analysis of the spectra by multivariate statistical techniques (principal component and canonical variate analysis) separated these exopolymers into distinct groups. Py-MS clearly distinguished characteristic fragments, which may be derived from components responsible for functional differences between polymers. The importance of these distinctions and the relevance of pyrolysis information to exopolysaccharide function in aquatic bacteria is discussed.

Ruminiclostridium 5, Parabacteroides distasonis, and bile acid profile are modulated by prebiotic diet and associate with facilitated sleep/clock realignment after chronic disruption of rhythms

Chronic disruption of rhythms (CDR) impacts sleep and can result in circadian misalignment of physiological systems which, in turn, is associated with increased disease risk. Exposure to repeated or severe stressors also disturbs sleep and diurnal rhythms. Prebiotic nutrients produce favorable changes in gut microbial ecology, the gut metabolome, and reduce several negative impacts of acute severe stressor exposure, including disturbed sleep, core body temperature rhythmicity, and gut microbial dysbiosis. In light of previous compelling evidence that prebiotic diet broadly reduces negative impacts of acute, severe stressors, we hypothesize that prebiotic diet will also effectively mitigate the negative impacts of chronic disruption of circadian rhythms on physiology and sleep/wake behavior. Male, Sprague Dawley rats were fed diets enriched in prebiotic substrates or calorically matched control chow. After 5 weeks on diet, rats were exposed to CDR (12 h light/dark reversal, weekly for 8 weeks) or remained on undisturbed normal light/dark cycles (NLD). Sleep EEG, core body temperature, and locomotor activity were recorded via biotelemetry in freely moving rats. Fecal samples were collected on experimental days -33, 0 (day of onset of CDR), and 42. Taxonomic identification and relative abundances of gut microbes were measured in fecal samples using 16S rRNA gene sequencing and shotgun metagenomics. Fecal primary, bacterially modified secondary, and conjugated bile acids were measured using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Prebiotic diet produced rapid and stable increases in the relative abundances of Parabacteroides distasonis and Ruminiclostridium 5. Shotgun metagenomics analyses confirmed reliable increases in relative abundances of Parabacteroides distasonis and Clostridium leptum, a member of the Ruminiclostridium genus. Prebiotic diet also modified fecal bile acid profiles; and based on correlational and step-wise regression analyses, Parabacteroides distasonis and Ruminiclostridium 5 were positively associated with each other and negatively associated with secondary and conjugated bile acids. Prebiotic diet, but not CDR, impacted beta diversity. Measures of alpha diversity evenness were decreased by CDR and prebiotic diet prevented that effect. Rats exposed to CDR while eating prebiotic, compared to control diet, more quickly realigned NREM sleep and core body temperature (ClockLab) diurnal rhythms to the altered light/dark cycle. Finally, both cholic acid and Ruminiclostridium 5 prior to CDR were associated with time to realign CBT rhythms to the new light/dark cycle after CDR; whereas both Ruminiclostridium 5 and taurocholic acid prior to CDR were associated with NREM sleep recovery after CDR. These results support our hypothesis and suggest that ingestion of prebiotic substrates is an effective strategy to increase the relative abundance of health promoting microbes, alter the fecal bile acid profile, and facilitate the recovery and realignment of sleep and diurnal rhythms after circadian disruption.

Treatment of post-operative infections following proximal femoral fractures: our institutional experience

Proximal femoral fractures (PFFs) are a major health concern in the elderly population. Improvements made in implants and surgical techniques resulted in faster rehabilitation and shorter length of hospital stay. Despite this, the reduced physiological reserve, associated co-morbidities and polypharmacy intake of the elderly population put them at high risk of postoperative complications particularly of infectious origin. Out of 10061 patients with proximal femoral fractures 105 (1.05%) developed surgical site infection; 76 (72%) infections occurred in patients who had sustained intracapsular (IC) fractures with the remaining 29 (28%) infections occurring in patients with extracapsular (EC) neck of femur fractures. The median number of additional surgical debridements was 2 (range 1-7). MRSA was isolated in 49 (47%) of the cases; 38 patients (36%) ultimately underwent a Girdlestone's excisional arthroplasty. Mortality at 30 days and 3 months was 10% and 31%, respectively. It was noted that post-operative hip infection predisposed to a prolonged length of stay in the acute unit and subsequently to a more dependent destination after discharge.

Bacteraemia in the adult intensive care unit of a teaching hospital in Nottingham, UK, 1985-1996

Bacteraemia is an important cause of morbidity and mortality in the intensive care unit. In this study the distribution of organisms causing bacteraemic episodes in patients in the adult intensive care unit of a large teaching hospital was determined. Particular emphasis was placed on the type of organisms isolated from community- and hospital-acquired bacteraemia, the suspected source of infection, the possible risk factors associated with bacteraemia, and outcome. The incidence of bacteraemia and fungaemia increased from 17.7 per 1000 admissions in 1985 to 80.3 in 1996. A total of 315 episodes of bacteraemia and fungaemia were documented over a 12-year period, of which 18% were considered community-acquired and 82% hospital-acquired. Gram-positive and gram-negative bacteria accounted for 46.9% and 31.5% of the episodes, respectively. Polymicrobial infection accounted for 17.8% and fungi for 3.8% of the episodes. Staphylococcus aureus (22.5%), Staphylococcus epidermidis (7.6%), and Streptococcus pneumoniae (7.9%) were the predominant gram-positive bacteria implicated, whereas Escherichia coli (6%), Enterobacter cloacae (7%), Klebsiella aerogenes (3.8%), Pseudomonas aeruginosa (5.1%), and Acinetobacter spp. (3.8%) were the predominant gram-negative bacteria isolated. The two most common sources of infection were the respiratory tract (39.7%) and an intravascular line (24.5%), but in 8.9% of episodes the focus of infection remained unknown. Bacteraemic patients stayed in the unit for a longer period (12 days) than did non-bacteraemic patients (3 days). The overall mortality related to bacteraemia and candidaemia was 44.4%. Surveillance of bacteraemia in the intensive care unit is important in detecting major changes in aetiology, e.g., the increasing incidence of gram-positive bacteraemia, the emergence of methicillin-resistant Staphylococcus aureus in 1995, and the emergence of Enterobacter cloacae. It is of value in determining empirical antimicrobial therapy to treat presumed infection pending a microbiological diagnosis and in directing the development of guidelines for infection prevention, e.g., guidelines for central venous catheter care.

Pyrolysis mass spectrometry studies on Bacillus anthracis, Bacillus cereus and their close relatives

Pyrolysis mass spectrometry was used to examine strains of B. anthracis, of B. cereus, of B.cereus either proven to cause emetic illness or connected with outbreaks of emetic food poisoning and of B.thuringiensis. Analysis of the data-set for all strains allowed differentiation between B.anthracis, the emetic B.cereus and B.thuringiensis but B.cereus strains could not be clearly discriminated. Removal of data for the B.thuringiensis and the emetic B.cereus strains, followed by re-analysis, allowed clear separation of the B. anthracis and B. cereus groups. Furthermore, PyMS was found to be capable of discriminating between some strains of B.anthracis, and demonstrating sub-groupings of others. This work provides further evidence of the ability of PyMS to distinguish rapidly between very closely related organisms and indicates its potential in epidemiology.

The Uk Academic Foundation Programmes: Are the Objectives Being Met?

Background

Since the Academic Foundation Programme was established in the UK in 2005 a number of trainees have participated in this programme; however, there are few published national data on the experiences of these academic trainees. We aimed to assess the perceived value and challenges of training on the AFP.

Methods

In March 2017, an anonymous electronic questionnaire was distributed to all Academic Foundation Programme trainees in the UK, via their local foundation school administrators.

Results

Fifty-six respondents completed the survey from 9 out of the 15 Academic Units of Application. Of these, 82% were undertaking a research based Academic Foundation Programme; however, 41% reported not having access to any training on research methods and governance. Sixty-six percent reported they were aware of the aims and expected outcomes of the Academic Foundation Programme, but the self-reported achievement of academic compendium outcomes was relatively low. Sixty-three percent rated the quality of their experience on the Academic Foundation Programme as excellent or good and 75% reported that they intended to continue in academia. Most trainees (64%) reported that the completion of a postgraduate qualification as part of their Academic Foundation Programme would improve the programme.

Conclusion

The Academic Foundation Programme plays a valuable role in trainees’ development and preparing them for a career in academia. However, the objectives of the programme are currently not being uniformly achieved. Furthermore, trainees feel there remains room for improvement in the design of the Programme.

Oral CBD-rich hemp extract modulates sterile inflammation in female and male rats

Introduction: Cannabidiol (CBD) extract from the cannabis plant has biomedical and nutraceutical potential. Unlike tetrahydrocannabinol (THC), CBD products produce few psychoactive effects and pose little risk for abuse. There is emerging preclinical and clinical evidence that CBD is stress modulatory and may have anti-inflammatory properties. People across the United States legally ingest CBD-rich hemp extracts to manage mental and physical health problems, including stress and inflammation. Preclinical studies have revealed potential mechanisms for these effects; however, the impact of this prior work is diminished because many studies: 1) tested synthetic CBD rather than CBD-rich hemp extracts containing terpenes and/or other cannabinoids thought to enhance therapeutic benefits; 2) administered CBD via injection into the peritoneal cavity or the brain instead of oral ingestion; and 3) failed to examine potential sex differences. To address these gaps in the literature, the following study tested the hypothesis that the voluntary oral ingestion of CBD-rich hemp extract will attenuate the impact of stressor exposure on plasma and tissue inflammatory and stress proteins in females and males. Methods: Adult male and female Sprague Dawley rats (10-15/group) were randomly assigned to be given cereal coated with either vehicle (coconut oil) or CBD-rich hemp extract (L-M0717, CBDrx/Functional Remedies, 20.0 mg/kg). After 7 days, rats were exposed to a well-established acute model of stress (100, 1.5 mA, 5-s, intermittent tail shocks, 90 min total duration) or remained in home cages as non-stressed controls. Results: Stressor exposure induced a robust stress response, i.e., increased plasma corticosterone and blood glucose, and decreased spleen weight (a surrogate measure of sympathetic nervous system activation). Overall, stress-induced increases in inflammatory and stress proteins were lower in females than males, and oral CBD-rich hemp extract constrained these responses in adipose tissue (AT) and mesenteric lymph nodes (MLN). Consistent with previous reports, females had higher levels of stress-evoked corticosterone compared to males, which may have contributed to the constrained inflammatory response measured in females. Discussion: Results from this study suggest that features of the acute stress response are impacted by oral ingestion of CBD-rich hemp extract in female and male rats, and the pattern of changes may be sex and tissue dependent.

GM1 inhibits early signaling events mediated by PDGF receptor in cultured human glioma cells

Binding of platelet-derived growth factor receptor (PDGF) to its receptor (PDGFR) activates its receptor tyrosine kinase which autophosphorylates tyrosine residues. The p85 regulatory subunit of phosphatidylinositol 3-kinase (PI 3-kinase) binds to specific phosphotyrosines on PDGFR-beta and through the associated p110 catalytic subunit of PI 3-kinase catalyzes the formation of lipids that are involved in intracellular signaling. We examined if GM1 affects interactions between PDGFR-beta and specific proteins involved in PDGFR-mediated signaling. U-1242 MG cells were studied under different growth conditions using immunoprecipitation and Western Blot analysis. PDGF-stimulated the association of PDGFR-beta with p85, ras GTPase-activating protein and PLC gamma. GM1 decreased these associations in parallel with decreased tyrosine phosphorylation of PDGFR. PDGF augmented the activity of PI 3-kinase associated with PDGFR-beta, and this was attenuated by GM1. However, GM1 did not alter SH2 domains of p85. GM1 probably inhibits PDGF-induced signaling proteins with PDGFR-beta by inhibiting phosphorylation of specific tyrosines on the receptor which bind to SH2-domains on signaling proteins.

How will care be rationed?

No bill before Congress fully answers the explosive question of who gets how much care--and who ultimately makes the hard choices. But experts say health care rationing of some kind is inevitable. Here's how to decipher the debate, and what it means for your practice.