Serial Imaging of Virus-Associated Necrotizing Disseminated Acute Leukoencephalopathy (VANDAL) in COVID-19.

BACKGROUND AND PURPOSE: Various patterns of leukoencephalopathy have been described in coronavirus disease 2019 (COVID-19). In this article, we aimed to describe the clinical and imaging features of acute disseminated leukoencephalopathy in critically ill patients with COVID-19 and the imaging evolution during a short-term follow-up. MATERIALS AND METHODS: We identified and reviewed the clinical data, laboratory results, imaging findings, and outcomes for 8 critically ill patients with COVID-19 with acute disseminated leukoencephalopathy. RESULTS: All patients demonstrated multiple areas of white matter changes in both cerebral hemispheres; 87.5% (7/8) of patients had a posterior predilection. Four patients (50%) had short-term follow-up imaging within a median of 17 days after the first MR imaging; they developed brain atrophy, and their white matter lesions evolved into necrotizing cystic cavitations. All (8/8) patients had inflammatory cytokine release syndrome as demonstrated by elevated interleukin-6, D-dimer, lactate dehydrogenase, erythrocyte sedimentation rate, C-reactive protein, and ferritin levels. Most (7/8; 87.5%) patients were on prolonged ventilator support (median, 44.5 days; interquartile range, 20.5 days). These patients had poor functional outcomes (6/8 [75%] patients were discharged with mRS 5) and high mortality (2/8, 25%). CONCLUSIONS: Critically ill patients with COVID-19 can develop acute disseminated leukoencephalopathy that evolves into cystic degeneration of white matter lesions with brain atrophy during a short period, which we dubbed virus-associated necrotizing disseminated acute leukoencephalopathy. This may be the result of COVID-19-related endothelial injury, cytokine storm, or thrombotic microangiopathy.

Suppression of primary T-cell responses and induction of alloantigen-specific hyporesponsiveness in vitro by the Janus kinase inhibitor tyrphostin AG490.

BACKGROUND: Tyrphostin AG490 has recently been shown to block interleukin (IL)-2 receptor gamma-chain-associated Janus kinase 3. Here, we analyzed the effect of AG490 on T-cell alloresponses in vitro. METHODS: For the evaluation of T-cell activation, DNA synthesis, surface marker expression, cytokine secretion, intracellular calcium mobilization, early protein tyrosine phosphorylation, and apoptosis were measured. RESULTS: AG490 effectively inhibited T-cell proliferation in human mixed lymphocyte culture (MLC) even when added 4 days after culture initiation. Inhibition of IL-2-dependent proliferation in T-cell blasts and the incapability of IL-2 or IL-15 to restore proliferation in AG490-treated MLC suggests interference with cytokine receptor signaling. T-cell receptor-triggered early protein tyrosine phosphorylation, calcium mobilization, up-regulation of CD69, and initial CD25 expression were not affected. Interestingly, AG490 substantially inhibited production of IL-2 and interferon-gamma in T cells stimulated with alloantigen or via CD3 and CD28. In CD28-independent activation models (e.g., stimulation with phorbol myristate acetate plus ionomycin), however, cytokine secretion was not inhibited. Pretreatment of primary MLC with AG490 resulted in substantial down-regulation of secondary responses to cells from the original donor as opposed to third-party cells or phytohemagglutinin. Unresponsiveness was induced also in T cells stimulated with CD3 monoclonal antibody. Induction of apoptosis in polyclonally activated T cells and the incapability of IL-2 to reverse specific hyporesponsiveness, suggest programmed cell death as an important mechanism underlying antigen-specific down-regulation of alloresponses. CONCLUSIONS: We demonstrate that AG490 blocks different manifestations of T-cell activation. This and its ability to induce alloantigen-specific hyporesponsiveness point to a potential use for interfering with alloreactivities in vivo.

Simultaneous recovery of beta-lactamase-negative and beta-lactamase-positive Haemophilus influenzae type b from cerebrospinal fluid of a neonate.

A case of Haemophilus influenzae type b meningitis in a neonate from whom both a beta-lactamase-negative and a beta-lactamase-positive strain were isolated simultaneously is reported. Both bacteriology laboratory technicians and clinicians should be aware of this phenomenon when performing sensitivity tests on H influenzae isolates or treating patients with serious H influenzae infection.

Stable prodrugs of n-butyric acid: suppression of T cell alloresponses in vitro and prolongation of heart allograft survival in a fully allogeneic rat strain combination.

n-Butyric acid has previously been shown in vitro to suppress T cell alloresponses and beyond that to induce a state of alloantigen-specific hyporesponsiveness suggesting a potential relevance for suppressing alloresponses also in vivo. The clinical use of butyrate salt derivatives, however, is limited by an extremely short half-life due to rapid metabolism. This prompted us to investigate the effect of butyric acid derivatives with prolonged residence time in vivo on T cell alloresponses in vitro and further to explore the immunosuppressive capacity of esterified n-butyric acid in vivo. First, the effect of three butyric acid esters, i.e. glucose pentabutyrate, diacetone glucose butyrate and tributyrin on T cell proliferation in a human mixed lymphocyte culture (MLC) was evaluated. All three derivatives were found to inhibit T cell alloresponses in a concentration-dependent manner. Based on the ED50 values, glucose pentabutyrate was found to be most effective in inhibiting T cell alloreactivity in vitro (11 microM), followed by diacetone glucose butyrate (122 microM), tributyrin (146 microM) and sodium butyrate (539 microM). Because of its favourable in vitro properties, glucose pentabutyrate was chosen for in vivo experiments. To test the effect of this compound on allograft survival in vivo, in the second part of this study, heterotopic heart transplants were performed in a high responder fully allogeneic rat strain combination (Brown Norway to Lewis strain rats). We found that intraperitoneal (i.p.) injection of glucose pentabutyrate at 500 mg/kg/day (day 0 and daily up to 12 days posttransplant) induced a significant prolongation of allograft survival as compared to animals treated with vehicle (glycerol formal, i.p.) alone (14.1+/-6.3 versus 9.6+/-3.2 days, p = 0.036), whereby at lower dosage (100 mg/kg/day) no such effect was observed (10.2+/-2.1 days, p = 0.21). Our findings suggest that stable prodrugs of n-butyric acid might have potential clinical relevance for inhibiting alloresponses in vivo.

Effects of metabotropic glutamate receptor activation on the cellular and network level in the lamprey spinal cord.

The effects of the metabotropic glutamate receptor (mGluR) agonist ACPD ((1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid) on single neurones and on the network underlying locomotion in the lamprey have been analysed. ACPD induces a depolarization in lamprey spinal cord neurones, which is insensitive to tetrodotoxin (TTX) and ionotropic glutamate receptor antagonists, but is reversibly blocked by the mGluR antagonist MCPG ((+)-alpha-methyl-4-carboxyphenylglycine). The ACPD-induced depolarization persists in a calcium-free solution or when the calcium channel blocker cadmium is added to the solution. At the network level ACPD causes an increased burst frequency during fictive locomotion by increasing the excitability level of network neurones.

Strategies for reducing Papanicolaou smear screening errors: principles derived from data and experience with quality control.

A number of principles pertaining to types of measurements of Papanicolaou smear accuracy are presented and implications with respect to quality control operations are explored. There are strengths and weaknesses inherent in each of the quality control methods available to us; choices regarding which of them to use and specifics regarding their implementation should be guided wherever possible by common sense and well-analyzed data as well as by regulatory requirements. Definitions of error in particular require careful attention from the points of view of both microscopic criteria and choice of reporting nomenclature. Other elements that characterize Papanicolaou smear screening environments, such as workload limits and new technologies, are also discussed.

Evaluation of costs and benefits of advances in cytologic technology. International Academy of Cytology Task Force summary. Diagnostic Cytology Towards the 21st Century: An International Expert Conference and Tutorial.

ISSUES: Uterine cervical cytology smears are among the most cost-effective cancer prevention interventions available, but they are not infallible, and new or modified technologies have been and will be proposed to improve diagnostic accuracy. Before these new technologies are accepted, their performance attributes will be carefully studied and defined. Equally important in this era of fiscal constraints are cost/benefit analyses, for which we review certain guidelines. CONSENSUS POSITION: In an effort to control rising costs in the health care sector, there has been a strong incentive to move toward a market system, and a variety of forces are acting to drive down expenditures. These same pressures will continue to be brought to bear on the providers of cervical cytology services. It must be emphasized that the technical knowledge required to define cost-effective medical practice lies within the medical profession itself, which must recognize the following: (a) Resources are finite; (b) Elimination of fraud, abuse and waste is not enough to bring health care expenditures down to levels considered acceptable to government and business; (c) The medical profession must take the responsibility to identify the health and economic consequences of the services it provides and make wise recommendations for allocation of resources to optimize health consequences. The analysis of costs and benefits must be viewed from a societal perspective and presented in terms of the marginal impact on current practice. This does not mean that new technologies must reduce cost; on the contrary, improvements in health can be expected to come at a price, but at a price commensurate with value gained in lives saved or in added quality adjusted life years. To be of value, a new technology for cervical cytology must be more effective in preventing cervical carcinoma. Dysplasia is considered a precursor of carcinoma, and detection of dysplasia has been a surrogate for prevention of cervical carcinoma, but dysplasia does not always lead to carcinoma, least of all mild dysplasia, and policy makers ultimately will insist that a favorable change in health outcome be effected by new technology before it is allocated resources. Alternatively, new technologies may lower cost, perhaps by modifying screening or rescreening procedures according to known risk; by improved cytopreparatory techniques that simplify, improve or speed screening; or by monitoring devices that minimize screening error. In each case the performance attributes of the instrument or human instrument process should be evaluated in the intended use environment. ONGOING ISSUES: While current cervical cytology methodology is one of the most effective means of cancer prevention, there continues to be development of new techniques to increase the sensitivity and specificity of this test. With present fiscal constraints, these will be subject to stringent cost/benefit analyses in which the medical profession must play a key role. Such analyses can be quite complicated, considering the additional costs or cost savings of clinical follow-up procedures and the reliability of dysplasias detected by cytology as a surrogate for cervical carcinoma in calculating quality of life years saved.

Quality assurance/control issues. International Academy of Cytology Task Force summary. Diagnostic Cytology Towards the 21st Century: An International Expert Conference and Tutorial.

ISSUES: General definitions of quality assurance and quality control (QA/C) have existed in many forms for decades, and a new discipline guides their application to diverse industrial and recently medical processes without much fanfare. However, in the field of cervical cytology screening, the range of QA/C options has recently broadened and become controversial. With the advent of new systems of terminology, larger-scale laboratories and new technologies--plus strong governmental and legal pressures in some nations--the range of extremely difficult and sometimes expensive QA/C choices our community faces is greater than ever. CONSENSUS POSITION: At our conference, the basic definitions of QA/C posed little difficulty. Presentation of the range of methods in use today and of those based on new technologies where use is proposed or has just begun also was achieved with little or no dispute. However, there was lack of consensus on exactly how QA/C methods are to be assessed. Indeed, there was little consistency in the use of different outcome measures with which we can judge success or failure of specific QA/C options. In addition, the tension between pressure to adopt sometimes uncertain or expensive method enhancements and pressure to maintain affordability and the widest possible access for populations that most need cervical cytology screening is greater than ever. ONGOING ISSUES: More data are required that would enable assessment of QA/C options with the clearest possible understanding of cost/benefits and current or new assumptions of risk. Other task forces, such as medicolegal, cost/benefit and those devoted to new technologies, are our essential partners in meeting the challenges described above.

[Chronic cough in children: signs of serious disease and investigations]. / Toux chronique de l'enfant: signes d'alarme et investigations.

Only in some particular cases chronic cough requires special investigations. Respiratory diseases linked to environment are frequent in children. Cough is the most common symptom in child asthma and usually occurs during sleep or exercise. Environmental tobacco smoke exposure may concern up to 30% of families. Questioning should systematically check for parental smoking in children with chronic cough since avoidance is the only effective treatment. The incidence of whooping cough appears to be increasing and the diagnosis may be difficult among already immunized children in whom symptoms are often nonspecific. Nowadays Bordetella pertussis can easily be detected on nasal smears (ELISA, PCR, cultures). Swallowing dysfunction may cause productive cough in toddlers, most often related to functional dyspraxia, yet possibly due to aerodigestive tract malformation. Unrecognized bronchial foreign body is a well-known pitfall particularly between 9 and 36 months of age. Bronchiectasis and cystic fibrosis are responsible for chronic productive cough in toddlers and older children. In teenagers, psychogenic coughing is difficult to manage and usually requires psycho- and speech therapy.

[Asthma and household chemical pollutants (with the exception of tobacco)]. / Asthme et polluants chimiques domestiques (à l'exception du tabac).

The relationship between allergens in a domestic environment and asthma has been extensively studied and it is only recently that studies have suggested the possibility of the role of chemical pollutants in the internal environment in the genesis of asthma. The pollutants studied are oxides of nitrogen (nitrogen dioxide NO2), volatile organic components (COV), formaldehyde, ozone (O3) and sulphur dioxide (SO2). The level of nitrogen dioxide in the interior of houses may be greater than those met outside. Normal values are 400 mcg per metre3 per hour and 150 mcg per metre3 in twenty four hours. In asthmatics challenge test to nitrogen dioxide and epidemiological studies suggest that internal nitrogen dioxide is capable of provoking asthmatic crises either by a direct pollutant effect or by potentialising the allergenic crises either by a direct pollutant effect or by potentialising the allergenic response of the bronchi. COV and formaldehyde are liberated by urea formaldehyde foams and by chipboard furniture. The levels of COV and formaldehyde inside a house may be up to 10 times higher than those outside. COV and formaldehyde perhaps would have an effect on the bronchi in asthmatics at significant levels which are rarely found in the domestic environment. Ozone is an external pollutant. However, from 5-80% of the external concentrations may be found inside some locations. Thus, in certain conditions which are relatively rare, the interior concentrations of dwelling places may attain levels which are capable of inducing, in healthy subjects who are sensitive to ozone, a drop in the FEV1. As regards asthmatics, only experimental work has been able to show any bronchospastic effect of ozone, either by a direct effect on the bronchi or by the potentiation of a bronchial response to allergens. It would be convenient to perform some epidemiological studies to determine if there is a relationship between exposure to ozone internally and to bronchial changes. The concentrations of SO2 inside houses increases when coal is burnt. The levels provoking a bronchial reaction are much greater than those found inside houses. The data and the literature which is mostly recent seems to stress the role of NO2 ozone and SO2 as a factor which might favour asthmatic crises induced by allergens in atopic subjects. However, other studies will be necessary to confirm the initial data.

Activation of pharmacologically distinct metabotropic glutamate receptors depresses reticulospinal-evoked monosynaptic EPSPs in the lamprey spinal cord.

1. Different metabotropic glutamate receptors (mGluRs) can modulate synaptic transmission in different regions in the CNS, but their roles at individual synaptic connections have not been detailed. We used paired intracellular recordings from reticulospinal axons and their postsynaptic target neurons in the lamprey spinal cord to investigate the effects of mGluR activation on glutamatergic synaptic transmission. 2. The mGluR agonists (1S,3R)-1-aminocyclopentane-1,3-dicarboxyylic acid [(1S,3R)-ACPD] and L(+)-2-amino-4-phosphonobutyric acid (L-AP4) both reduced the amplitude of monosynaptic excitatory postsynaptic potentials (EPSPs) elicited by stimulation of single reticulospinal axons. The depression of monosynaptic unitary EPSPs occurred without any apparent change in the input resistance of postsynaptic neurons. Furthermore, the mGluR agonists did not affect the amplitude of (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-induced depolarizations. Taken together, these results thus suggest that (1S,3R)-ACPD and L-AP4 depress reticulospinal synaptic transmission via presynaptic mechanisms. 3. (2S,1'S,2'S)-2-(carboxycyclopropyl) glycine (L-CCG-I), which selectively activates group II mGluRs, also reduced the amplitude of reticulospinal-evoked EPSPs without any apparent change in the input resistance or membrane potential of the postsynaptic neuron. 4. The mGluR antagonist alpha-methyl-L-AP4 blocked the depression induced by L-AP4 but not that induced by (1S,3R)-ACPD. Furthermore, the effects of coapplication of (1S,3R)-ACPD and L-AP4 were additive, suggesting that they inhibit synaptic transmission by an action on pharmacologically distinct mGluRs. 5. These results provide evidence for the colocalization of at least two different subtypes of presynaptic mGluRs on a single reticulospinal axon in the lamprey. These presynaptic mGluRs could serve as glutamatergic autoreceptors limiting the extent of reticulospinal-mediated excitation of spinal neurons.

Endogenous activation of metabotropic glutamate receptors contributes to burst frequency regulation in the lamprey locomotor network.

The effect of metabotropic glutamate receptor (mGluR) agonists and antagonists on the spinal cord network underlying locomotion in the lamprey has been analysed. The specific group I mGluR agonist (R,S)-3,5-dihydroxyphenylglycine (DHPG) and the broad-spectrum mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) both increased the burst frequency of N-methyl-D-aspartic acid (NMDA)-induced fictive locomotion and depolarized grey matter neurons. The burst frequency increase induced by the mGluR agonists was counteracted by the mGluR antagonists (+)-alpha-methyl-4-carboxyphenylglycine ((+)-MCPG), cyclopropan[b]chromen-1a-carboxylic acid ethylester (CPCCOEt) and (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA). Application of CPCCOEt alone reduced the locomotor burst frequency, indicating that mGluRs are endogenously activated during fictive locomotion. The mGluR antagonist CPCCOEt had no effect on NMDA-, or (S)-alpha-amino-3-hydroxy-5-methyl-4-isoazolepropionic acid (AMPA)-induced depolarizations. The mGluR agonists 1S,3R-ACPD and DHPG increased the amplitude of NMDA-induced depolarizations, a mechanism which could account for the increase in burst frequency. The group III mGluR agonist L-2-amino-4-phosphonobutyric acid reduced intraspinal synaptic transmission and burst frequency.

Calcium channels involved in synaptic transmission from reticulospinal axons in lamprey.

The pharmacology of calcium channels involved in glutamatergic synaptic transmission from reticulospinal axons in the lamprey spinal cord was analyzed with specific agonists and antagonists of different high-voltage activated calcium channels. The N-type calcium channel blocker omega-conotoxin GVIA (omega-CgTx) induced a large decrease of the amplitude of reticulospinal-evoked excitatory postsynaptic potentials (EPSPs). The P/Q-type calcium channel blocker omega-agatoxin IVA (omega-Aga) also reduced the amplitude of the reticulospinal EPSPs, but to a lesser extent than omega-CgTx. The dihydropyridine agonist Bay K and antagonist nimodipine had no effect on the amplitude of the reticulospinal EPSP. Combined application of omega-CgTx and omega-Aga strongly decreased the amplitude the EPSPs but was never able to completely block them, indicating that calcium channels insensitive to these toxins (R-type) are also involved in synaptic transmission from reticulospinal axons. We have previously shown that the group III metabotropic glutamate receptor agonist L(+)-2-amino-4-phosphonobutyric acid (L-AP4) mediates presynaptic inhibition at the reticulospinal synapse. To test if this presynaptic effect is mediated through inhibition of calcium influx, the effect of L-AP4 on reticulospinal transmission was tested before and after blockade of N-type channels, which contribute predominantly to transmitter release at this synapse. Blocking the N-type channels with omega-CgTx did not prevent inhibition of reticulospinal synaptic transmission by L-AP4. In addition, L-AP4 had no affect on the calcium current recorded in the somata of reticulospinal neurons or on the calcium component of action potentials in reticulospinal axons. These results show that synaptic transmission from reticulospinal axons in the lamprey is mediated by calcium influx through N-, P/Q- and R-type channels, with N-type channels playing the major role. Furthermore, presynaptic inhibition of reticulospinal transmission by L-AP4 appears not to be mediated through inhibition of presynaptic calcium channels.

A practical guide to Papanicolaou smear rescreens: how many slides must be reevaluated to make a statistically valid assessment of screening performance?

BACKGROUND: The question of the minimum number of Papanicolaou (Pap) smear slides that must be rescreened to draw statistically valid conclusions regarding the accuracy of screening often is raised. No method for generating answers in varying laboratory circumstances has achieved widespread application; standard statistical sample size calculations may represent such a resource. METHODS: A series of tables was constructed to display minimum required numbers of rescreens, with each table representing differing hypothetical laboratory circumstances. To use each table, assumptions must be specified in advance as to prevalence of abnormality, definition of error, baseline false-negative proportions (FNPs) of performance, and a degree of increase in FNPs that is considered a departure from baseline warranting concern, among others. RESULTS: The authors constructed four sample tables displaying minimum numbers of slides that must be rescreened in differing specified laboratory scenarios. Depending on assumed conditions and predetermined levels of satisfactory and unsatisfactory accuracy, the range of numbers is very broad (38-10,000). One example representing likely conditions indicates that 1040 slides must be reexamined; in another scenario, a sample size of 300 is sufficient. CONCLUSIONS: The minimum number of rescreened slides needed to draw statistically valid conclusions regarding Pap smear screening accuracy can be calculated using standard statistical methods. However, a number of assumptions must be detailed in advance. The authors offer this as a practical guide and a continuation of a general inquiry regarding Pap smear error rate measurement and display. The use of these tables raises at least as many questions as it answers, but still may represent a significant advance. Future efforts at further numeric characterization of aspects of Pap smear screening performance are warranted to enable rational decision making when performance is examined in the course of quality assurance, and during quality control and regulatory activities. [See editorial on pages 127-9, this issue.]