AgDscam, a Hypervariable Immunoglobulin Domain-Containing Receptor of the Anopheles gambiae Innate Immune System

Activation of the insect innate immune system is dependent on a limited number of pattern recognition receptors (PRRs) capable of interacting with pathogen-associated molecular pattern. Here we report a novel role of an alternatively spliced hypervariable immunoglobulin domain-encoding gene, Dscam, in generating a broad range of PRRs implicated in immune defense in the malaria vector Anopheles gambiae. The mosquito Down syndrome cell adhesion molecule gene, AgDscam, has a complex genome organization with 101 exons that can produce over 31,000 potential alternative splice forms with different combinations of adhesive domains and interaction specificities. AgDscam responds to infection by producing pathogen challenge-specific splice form repertoires. Transient silencing of AgDscam compromises the mosquito's resistance to infections with bacteria and the malaria parasite Plasmodium. AgDscam is mediating phagocytosis of bacteria with which it can associate and defend against in a splice form–specific manner. AgDscam is a hypervariable PRR of the A. gambiae innate immune system

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Saccadic Palsy following Cardiac Surgery: Possible Role of Perineuronal Nets.

Perineuronal nets (PN) form a specialized extracellular matrix around certain highly active neurons within the central nervous system and may help to stabilize synaptic contacts, promote local ion homeostasis, or play a protective role. Within the ocular motor system, excitatory burst neurons and omnipause neurons are highly active cells that generate rapid eye movements - saccades; both groups of neurons contain the calcium-binding protein parvalbumin and are ensheathed by PN. Experimental lesions of excitatory burst neurons and omnipause neurons cause slowing or complete loss of saccades. Selective palsy of saccades in humans is reported following cardiac surgery, but such cases have shown normal brainstem neuroimaging, with only one clinicopathological study that demonstrated paramedian pontine infarction. Our objective was to test the hypothesis that lesions of PN surrounding these brainstem saccade-related neurons may cause saccadic palsy.Together with four controls we studied the brain of a patient who had developed a permanent selective saccadic palsy following cardiac surgery and died several years later. Sections of formalin-fixed paraffin-embedded brainstem blocks were applied to double-immunoperoxidase staining of parvalbumin and three different components of PN. Triple immunofluorescence labeling for all PN components served as internal controls. Combined immunostaining of parvalbumin and synaptophysin revealed the presence of synapses.Excitatory burst neurons and omnipause neurons were preserved and still received synaptic input, but their surrounding PN showed severe loss or fragmentation.Our findings support current models and experimental studies of the brainstem saccade-generating neurons and indicate that damage to PN may permanently impair the function of these neurons that the PN ensheathe. How a postulated hypoxic mechanism could selectively damage the PN remains unclear. We propose that the well-studied saccadic eye movement system provides an accessible model to evaluate the role of PN in health and disease

Temporal evolution of ischemic lesions in nonhuman primates: a diffusion and perfusion MRI study.

BACKGROUND AND PURPOSE:Diffusion-weighted imaging (DWI) and perfusion MRI were used to examine the spatiotemporal evolution of stroke lesions in adult macaques with ischemic occlusion. METHODS:Permanent MCA occlusion was induced with silk sutures through an interventional approach via the femoral artery in adult rhesus monkeys (n = 8, 10-21 years old). The stroke lesions were examined with high-resolution DWI and perfusion MRI, and T2-weighted imaging (T2W) on a clinical 3T scanner at 1-6, 48, and 96 hours post occlusion and validated with H&E staining. RESULTS:The stroke infarct evolved via a natural logarithmic pattern with the mean infarct growth rate = 1.38 ± 1.32 ml per logarithmic time scale (hours) (n = 7) in the hyperacute phase (1-6 hours). The mean infarct volume after 6 hours post occlusion was 3.6±2.8 ml (n = 7, by DWI) and increased to 3.9±2.9 ml (n = 5, by T2W) after 48 hours, and to 4.7±2.2ml (n = 3, by T2W) after 96 hours post occlusion. The infarct volumes predicted by the natural logarithmic function were correlated significantly with the T2W-derived lesion volumes (n = 5, r = 0.92, p = 0.01) at 48 hours post occlusion. The final infarct volumes derived from T2W were correlated significantly with those from H&E staining (r = 0.999, p < 0.0001, n = 4). In addition, the diffusion-perfusion mismatch was visible generally at 6 hours but nearly diminished at 48 hours post occlusion. CONCLUSION:The infarct evolution follows a natural logarithmic pattern in the hyperacute phase of stroke. The logarithmic pattern of evolution could last up to 48 hours after stroke onset and may be used to predict the infarct volume growth during the acute phase of ischemic stroke. The nonhuman primate model, MRI protocols, and post data processing strategy may provide an excellent platform for characterizing the evolution of acute stroke lesion in mechanistic studies and therapeutic interventions of stroke disease

A telepathology based screening tool for COVID-19 by leveraging morphological changes related to leukocytes in peripheral blood smears

As we approach the aftermath of a global pandemic caused by Severe Acute Respiratory Syndrome-Corona Virus (SARS-CoV-2), the importance of quickly developing rapid screening tests has become very clear from the point of view of containment and also saving lives. Here, we present an explorative study to develop a telepathology-based screening tool using peripheral blood smears (PBS) to identify Coronavirus Disease (COVID-19)-positive cases from a group of 138 patients with flu-like symptoms, consisting of 82 positive and 56 negative samples. Stained blood smear slides were imaged using an automated slide scanner (AI 100) and the images uploaded to the cloud were analyzed by a pathologist to generate semi-quantitative leukocyte morphology-related data. These telepathology data were compared with the data generated from manual microscopy of the same set of smear slides and also the same pathologist. Besides good correlation between the data from telepathology and manual microscopy, we were able to achieve a sensitivity and specificity of 0.83 and 0.71, respectively, for identifying positive and negative COVID-19 cases using a six-parameter combination associated with leukocyte morphology. The morphological features included plasmacytoid cells, neutrophil dysplastic promyelocyte, neutrophil blast-like cells, apoptotic cells, smudged neutrophil, and neutrophil-to-immature granulocyte ratio. Although Polymerase Chain Reaction (PCR) and antibody tests have a superior performance, the PBS-based telepathology tool presented here has the potential to be an interim screening tool in resource-limited settings in underdeveloped and developing countries

Absent or fragmented omnipause neuron perineuronal net triple immunofluorescence staining.

<p>Triple immunofluorescence staining for different components of perineuronal nets, revealed by a confocal laser scanning microscope. In the control case, omnipause neurons (OPN) are ensheathed by prominent perineuronal nets showing the same appearance with antibodies against the link protein (HPLN1), chondroitin sulfate proteoglycan (CSPG) and aggrecan (ACAN) (A, D, G, arrow). In the saccadic palsy patient, the neurons of the superior olive (SO) from the same sections as OPN are ensheathed by prominent perineuronal nets revealed by immunostaining of HPLN1, CSPG, and ACAN (C, F, I, arrows). However, around OPN (asterisk) in the patient, only HPLN1-based perineuronal nets can be detected, which appear fragmented (B, arrow). CSPG- and ACAN-immunostaining does not reveal perineuronal nets, but only few fragments along a few dendrites (E, H, arrow). Scale bars A,D,G = 20μm; B,C,E,F,H,I = 200μm.</p

Histologically normal omnipause neurons.

<p>Omnipause neurons in the nucleus raphe interpositus (RIP) appear histologically normal (arrows). (A) Photograph of a transverse section of the pons at the level of RIP. The inset indicates the area shown in A. (B) LFB-PAS staining showed no evidence of demyelination. (C) CR 3/43 staining showed no abnormal microglial activation. (D) GFAP staining showed no reactive gliosis. The asterisk labels the same blood vessel in neighboring sections for orientation. LFB-PAS, Luxol fast blue periodic acid-Schiff; GFAP, glial fibrillary acidic protein. Scale bar A = 500μm, inset = 5mm; B-D = 200μm.</p

Brainstem cutting planes and transverse sections.

<p>(A) Brainstem sagittal view demonstrating cutting planes. The blocks containing the rostral interstitial nucleus of the medial longitudinal fascicle (RIMLF), the oculomotor nucleus (nIII), the paramedian pontine reticular formation (PPRF) including the excitatory (EBN) and inhibitory burst neurons (IBN), the nucleus raphe interpositus (RIP) containing omnipause neurons (OPN), and the abducens nucleus (nVI), were cut in series of 10μm and 5μm thick sections. (B) Caudal view of the block containing the RIMLF. (C) Caudal view of the block containing the PPRF and OPN region. Scale bar B,C = 1cm. INC, interstitial nucleus of Cajal; IO, inferior olive; MB, mammillary body; LGN, lateral geniculate nucleus; MCP, medial cerebellar peduncle; MGN, medial geniculate nucleus; MT, mammillothalamic tract; nIV, trochlear nucleus; NVI, abducens nerve; PC, posterior commissure; RN, red nucleus; TR, tractus retroflexus; PC, posterior commissure; PUL, pulvinar; SC, superior colliculus; SCP, superior cerebellar peduncle; SN, substantia nigra.</p

Normal abducens nucleus perineuronal net immunostaining.

<p>Detection of perineuronal nets by aggrecan (ACAN) immunolabeling in the abducens nucleus (nVI) appeared similar in control subject and patient specimens. Low power (A and B) and high power (C and D) views of parvalbumin-positive (PAV) abducens neurons (brown) ensheathed by aggrecan (ACAN)-immunoreactive perineuronal nets (black, arrows). In the tissue from the control (A and C) and from the patient (B and D), ACAN-stained perineuronal nets (arrows) appeared in unaltered manner. Low power (E and F) and high power (G and H) photographs of the inhibitory burst neurons (IBN) of the control (E and G) and patient (F and H) displaying similar perineuronal nets around PAV-positive IBN. Scale bars A,B,E,F = 100μm; C,D,G,H = 30μm.</p