Un cadre conceptuel pour étudier la relation de causalité entre des variants du SARS-CoV-2 et la sévérité de la COVID-19 chez les patients hospitalisés

Contexte

Les souches de SARS-CoV-2 évoluent continuellement en accumulant des mutations dans leur génome au cours de la pandémie. Nous présentons ici un cadre conceptuel général qui permet d'étudier l'effet des variants du SARS-CoV-2 sur la sévérité de la maladie COVID-19.

Méthodes

Nous utilisons un graphe acyclique orienté (« Directed Acyclic Graph » ou DAG) pour énoncer explicitement les hypothèses sous-jacentes qui sont faites pour estimer l'effet causal de l'infection par un variant du SARS-CoV-2 sur la sévérité de la maladie COVID-19 chez des patients hospitalisés. Les DAGs sont aussi utilisés pour explorer les différents designs d’étude avec leur risque de biais de sélection. Ensuite, l'infrastructure de données spécifiques à la surveillance du COVID-19 en Belgique est décrite, avec ses forces et ses faiblesses pour étudier l'impact clinique des variants.

Résultats

Un modèle causal est défini et visualisé à l'aide d'un DAG, sur lequel figurent les variables aléatoires mesurées et d'autres non mesurées. Différentes méthodes, dont un design de cohortes appariées, sont proposées pour fixer les associations non causales. Les biais de sélection potentiels, notamment dans la sélection des patients pour un séquençage du génome complet (WGS) en se basant sur la charge virale ou la sévérité de l'infection, sont mis en évidence. Les limites de l'infrastructure de données actuelle, y compris l'enregistrement non exhaustif des patients hospitalisés pour COVID-19, sont décrites.

Discussion/Conclusion

Un cadre bien établi qui fournit une vue complète de la sévérité de la maladie COVID-19 en combinant des informations provenant de différentes sources, permettra d'évaluer l'impact clinique des variants émergents. Le cadre montre la complexité liée à la recherche causale, les données nécessaires correspondantes et il souligne des limitations importantes comme des facteurs de confusion non mesurés ou un biais de sélection, inhérentes à la réorientation des registres de données COVID-19 de routine existants.

Déclaration de liens d'intérêts

Les auteurs déclarent ne pas avoir de liens d'intérêts.

Diagnostic performance of seven rapid IgG/IgM antibody tests and the Euroimmun IgA/IgG ELISA in COVID-19 patients

OBJECTIVES

To evaluate the diagnostic performance of seven rapid IgG/IgM tests and the Euroimmun IgA/IgG ELISA for antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in COVID-19 patients.

METHODS

Specificity was evaluated in 103 samples collected before January 2020. Sensitivity and time to seropositivity was evaluated in 167 samples from 94 patients with COVID-19 confirmed with RT-PCR on nasopharyngeal swab.

RESULTS

Specificity (confidence interval) of lateral flow assays (LFAs) was ≥91.3% (84.0-95.5) for IgM, ≥90.3% (82.9-94.8) for IgG, and ≥85.4% (77.2-91.1) for the combination IgM OR IgG. Specificity of the ELISA was 96.1% (90.1-98.8) for IgG and only 73.8% (64.5-81.4) for IgA. Sensitivity 14-25 days after the onset of symptoms was between ≥92.1% (78.5-98.0) and 100% (95.7-100) for IgG LFA compared to 89.5% (75.3-96.4) for IgG ELISA. Positivity of IgM OR IgG for LFA resulted in a decrease in specificity compared to IgG alone without a gain in diagnostic performance, except for VivaDiag. The results for IgM varied significantly between the LFAs with an average overall agreement of only 70% compared to 89% for IgG. The average dynamic trend to seropositivity for IgM was not shorter than for IgG. At the time of hospital admission the sensitivity of LFA was <60%.

CONCLUSIONS

Sensitivity for the detection of IgG antibodies 14-25 days after the onset of symptoms was ≥92.1% for all seven LFAs compared to 89.5% for the IgG ELISA. The results for IgM varied significantly, and including IgM antibodies in addition to IgG for the interpretation of LFAs did not improve the diagnostic performance.

Ability of Emergency Department Physicians Using a Functional Autonomy-Assessing Version of the Triage Risk Screening Tool to Detect Frail Older Patients Who Require Mobile Geriatric Team Consultation

OBJECTIVES

Frailty in older people associates with poor outcomes. Screening by ED physicians would greatly facilitate detection of frail older patients but our previous attempt to introduce routine ED-physician screening with Short Emergency Geriatric Assessment (SEGA), a 13-item frailty tool that French geriatricians use to identify frail patients, failed due to its length and complexity. A national committee recently generated a new version of the fast and simple 5-item Triage Risk Screening Tool (TRST) in which a subjective item ('nurse concern') was replaced by an item assessing basic activities of daily living. The ability of ED physicians using this French-TRST to accurately detect frail patients who require comprehensive geriatric assessment was assessed.

DESIGN

Prospective cross-sectional study on diagnostic accuracy relative to the gold standard, namely, geriatrician-administered SEGA.

SETTING

Tertiary-care hospital, France.

SUBJECTS AND MEASUREMENTS

The participants were 498 ≥75-year-old patients who visited the ED in 2018-2019 and were administered French-TRSTs by first ED physicians and then geriatricians, followed by SEGA, all within 24 hours. Diagnostic accuracy variables were calculated. Geriatrician-TRST was used to identify TRST items that associated with ED physician misclassification of frail patients.

RESULTS

Emergency-TRST was significantly less sensitive than Geriatrician-TRST (88% vs. 93%; p=0.04) and tended to have lower negative predictive value (66% vs. 77%; p=0.09). Emergency-TRSTs rated four French-TRST items less well than Geriatrician-TRSTs.

CONCLUSIONS

As a substitute for SEGA in the ED, the French-TRST performed quite well overall but the ED physicians detected frail patients less well than the geriatricians. Modifications of the French-TRST that may improve the diagnostic performance of ED physicians are discussed.

Ruptured aortic aneurysm due to Mycobacterium bovis BCG with a delayed bacteriological diagnosis due to false negative result of the MPB 64 immunochromatographic assay

Background

Adjuvant therapy with bacillus Calmette–Guerin (BCG), a live attenuated strain of Mycobacterium bovis, has become the treatment of choice for low-risk superficial bladder carcinoma following transurethral resection of the bladder. Complications following vesical BCG instillations are uncommon but, in some cases, severe side-effects can occur such as sepsis or mycotic aneurysm. Besides usual laboratory techniques used for the diagnosis of Mycobacterium tuberculosis complex (MTBC) infections (smear microscopy and cultures), commercial immunochromatographic assays detecting MBP64, a 24 kDa M. tuberculosis complex-specific secretory protein, can rapidly distinguish MTBC and non-tuberculosis mycobacteria (NTM). MPB64 is found in M. tuberculosis, M. bovis and some but not all substrains of M.bovis BCG. Therefore, these immunochromatographic tests can lead to false negative results and delayed bacteriological diagnosis depending on the presence or absence of MPB64 protein in BCG substrains used for intravesical therapy.

Case presentation

We report the case of a 78-year-old male patient who was admitted to the hospital because of a 1-month history of unexplained fever, thrill, weight-loss and general malaise. His past medical history was marked by a non-muscle-invasive bladder carcinoma treated by transurethral resection followed by BCG instillations (Oncotice, Merck, USA). The patient was initially treated for a urinary tract infection but as fever persists after 72 h of antibiotherapy, urinary tract ultrasound was performed and revealed a large abdominal aortic aneurysm confirmed by computed tomography. Surgery was performed after multidisciplinary discussion. Direct smear of perioperative samples revealed acid-fast bacilli and both solid and liquid cultures were massively positive. Rapid identification of the positive mycobacterial culture was performed using an immunochromatographic assay based on the detection of the Mycobacterium tuberculosis MPB 64 antigen. The result was negative for Mycobacterium tuberculosis complex. After review of the medical record, a polymerase chain reaction (PCR) was performed and gave a positive result for M. tuberculosis complex. Anti-tuberculosis therapy was started immediately and the patient evolved favorably.

Conclusions

Through this case, we showed how the utilisation of MPB64 immunochromatographic assays can provide misleading information due to the variable presence of this protein among the different BCG strains. This case further illustrates the utility of rapid TB complex-specific PCR assays which provide a more reliable identification of all MTBC species.

Novel rapid PCR for the detection of Ile491Phe rpoB mutation of Mycobacterium tuberculosis, a rifampicin-resistance-conferring mutation undetected by commercial assays

OBJECTIVES

Neither the liquid medium-based Bactec MGIT, nor commercial molecular assays such as the Xpert MTB/RIF and the MTBDRplus V2.0 assays are capable of detecting up to 30% of rifampicin-resistant Mycobacterium tuberculosis strains in Swaziland because of the large proportion of the rpoB Ile491Phe mutations. In other countries, the frequency of this mutation is thought to be low.

METHODS

We designed a real-time multiplex allele-specific PCR assay to identify the rpoB Ile491Phe mutation responsible for these undetected resistant M. tuberculosis strains.

RESULTS

The technique showed 100% similarity with rpoB sequencing on a panel of 78 strains from Swaziland.

CONCLUSIONS

We propose that the detection of the rpoB Ile491Phe rpoB mutation should complement commercial assays for the diagnosis of rifampicin-resistant M. tuberculosis in routine conditions, particularly in countries where this specific mutation is frequent. The technique proposed in this paper is adapted for most reference laboratories.

Octopamine Modulates the Sensitivity of Limulus Ventral Photoreceptor

The effect of extracellularly applied octopamine (10-5mol/l) on the receptor potential of the Limulus ventral photoreceptor was studied. Octopamine increases the sensitivity of the photoreceptor in the light-adapted state more than in the dark-adapted state. Extracellular application of phentolamine (10-5mol/l) has an opposite, antagonizing effect. The octopamine effect, though reproducible in the individual experiment, varies greatly from preparation to preparation.

[Helping the highly dependent smokers]

Many smokers have difficulty in stopping smoking, either motivated to stop or forced for health, economic or statutory reasons. They have in common a heavy tobacco dependence and a high level of cigarette consumption. Often they combined factors impairing success in the attempt to stop smoking : e. g. anxio-depressive disorders, use of psychoactive substances, socio-economic deprivation. Smoking cessation specialists must optimize their interventions in order to improve the care of these highly dependent smokers.

Highly sensitive parylene membrane-based ac-calorimeter for small mass magnetic samples

We report the microfabrication and operation of a highly sensitive ac-calorimeter designed to characterize small mass magnetic systems operating at very low frequencies (from 0.1 to 5 Hz) in a temperature range from 20 to 300 K. The calorimetric cell is built in the center of a 500 nm thick polymeric membrane of parylene C held up by a Cu frame. On both sides of the membrane defining a three layer structure, electrical leads, heater, and thermometer are deposited as thin film layers of NbN(x), with different nitrogen contents, taking benefit of the poor thermal conductance of niobium nitride to thermally isolate the system. This suspended structure ensures very low heat capacity addenda with values in the microJ/K over the 1 mm(2) area of the measurement cell. The structuring of the membrane along with suspending of the sensing part only by the parylene bridges leads to a highly reduced thermal link. The calorimeter has been characterized as a function of frequency, temperature, and magnetic field. The thermal link measured is really small reaching values well below 10(-8) W/K at 50 K. With these characteristics the frequency of adiabaticity is typically around few hertz and energy exchanges as small as 1 pJ can be detected. Measurements have been performed on Co/Au thin films and on the GdAl(2) microcrystal where the ferromagnetic phase transition is clearly evidenced.

[Fibromyalgia prevalence in Tunisia]

OBJECTIVE

to estimate fibromyalgia (FM) prevalence in Tunisia.

METHODS

Data on a cross-section of 1000 individuals aged 15 years or older living in Sfax were collected by interviewers using the London Fibromyalgia Epidemiology Study Screening Questionnaire (LFES- SQ). The sampling was realized by empirical poll and respecting quota according to delegation, rural or urban environment, sex and age according to the demographic national data. The positive screened subjects were invited to be examined to confirm or exclude the FM by applying the 1999 ACR criteria. The questionnaire was administered to a second group of 252 volunteers, all were afterward examined. This allowed to study specificity and sensibility of the questionnaire and allowed to calculate the FM prevalence.

RESULTS

159 subjects were screened positive, only 141 were examined. The specialized exam allowed confirming the diagnosis of FM in 67 subjects. FM prevalence is different according to sex, age, study level and socio-economic level. Two hundred and fifty two volunteers answered the questionnaire then all examined. The questionnaire specificity was 90.8% and the sensibility 79.4%. FM prevalence in Tunisia, calculated by Bayes theorem, is estimated between 8.27% and 12.3%.

CONCLUSION

FM prevalence in Tunisia is estimated at least at 8.27%.

Qualité de vie de l'enfant polyhandicapé: questionnaire portant sur l'influence de l'état de santé et de l'alimentation entérale

To resort to gastrostomy feeding is a difficult decision to take in children with severe disability, the objective being better quality of life.

OBJECTIVES

To describe quality of life in children with severe disability and to look for factors which influence this quality of life, in particular gastrostomy.

METHOD

Descriptive study in 28 patients, aged 1 to 18 years, with severe motor and mental disability, with or without gastrostomy. The studied factors were: health and nutritional status and quality of life. The quality of life was evaluated with QUALIN questionnaire, specifically designed for infants.

RESULTS

This questionnaire was pertinent and well accepted by the family. Quality of life was influenced by capacity of communication (P=0.006), quality of sleeping (P=0.004), digestive problems (P<0.05) and age (P=0.031).

CONCLUSION

Gastrostomy did not impair quality of life. Its benefit was estimated as high as 8.71/10 in average by parents.

Inhalation of ultrafine carbon particles triggers biphasic pro-inflammatory response in the mouse lung

High levels of particulate matter in ambient air are associated with increased respiratory and cardiovascular health problems. It has been hypothesised that it is the ultrafine particle fraction (diameter <100 nm) that is largely responsible for these effects. To evaluate the associated mechanisms on a molecular level, the current authors applied an expression profiling approach. Healthy mice were exposed to either ultrafine carbon particles (UFCPs; mass concentration 380 microg x m(-3)) or filtered air for 4 and 24 h. Histology of the lungs did not indicate any pathomorphological changes after inhalation. Examination of the bronchoalveolar lavage fluid revealed a small increase in polymorphonuclear cell number (ranging 0.6-1%) after UFCP inhalation, compared with clean air controls, suggesting a minor inflammatory response. However, DNA microarray profile analysis revealed a clearly biphasic response to particle exposure. After 4 h of inhalation, mainly heat shock proteins were induced, whereas after 24 h, different immunomodulatory proteins (osteopontin, galectin-3 and lipocalin-2) were upregulated in alveolar macrophages and septal cells. In conclusion, these data indicate that inhalation of ultrafine carbon particles triggers a biphasic pro-inflammatory process in the lung, involving the activation of macrophages and the upregulation of immunomodulatory proteins.

Le syndrome de Netherton : une ectodermatose du petit nourrisson avec retard de croissance, déficit immunitaire et rachitisme. À propos de 3 cas

We report the cases of 2 boys and 1 girl suffering from Netherton syndrome. Both boys presented with a non-bullous congenital erythroderma and were diagnosed early as Netherton syndrome with hair biopsies. Both had severe failure to thrive, signs of atopy, several episodes of bacterial infection, and rickets (with a high blood level of vitamin D in the first boy, and vitamin D deficiency in the second). In the third case, the pilar abnormality appeared at the age of 3 years. The girl had ichtyosis linearis circumflexa, failure to thrive and severe constipation. Netherton syndrome is a rare disorder characterized by severe ichtyosis, signs of atopy, immune deficiency and failure to thrive. The disease is severe and comprises many complications in early infancy. It is due to a genetic disorder of recessive autosomal transmission, and the gene, SPINK5, is located in the chromosome 5. Prenatal diagnosis is possible. Two of our patients had rickets, which has never been described in such patients population.

Haemodynamic effects of an angiotensin-converting enzyme inhibitor and angiotensin receptor antagonist during hypovolaemia in the anaesthetized pig

BACKGROUND

Renin-angiotensin system antagonists, either angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor (AT(1)) antagonists, may interfere with regulation of arterial pressure during anaesthesia. This study aimed to compare the haemodynamic profile of anaesthetized pigs, which were subjected to haemorrhage in the presence of the ACE inhibitor enalaprilat or the AT(1) antagonist valsartan.

METHODS

Thirty-six pigs were assigned randomly to placebo, enalaprilat or valsartan groups. After a 30-min period of stabilization following anaesthesia and injection of the study drug, the animals were bled in two equal steps of 20% of their estimated blood volume (20% BV and 40% BV).

RESULTS

After bleeding of 20% BV, the mean arterial pressure (MAP) decreased significantly but similarly in each group (20-25%) but the placebo and the enalaprilat groups had a significant decrease in cardiac index (CI, 22% and 16%, respectively) without significant change in systemic vascular resistance (SVR). Conversely, in the valsartan group, SVR decreased significantly (23%, P<0.02 vs other groups) without significant change in CI (-4%). After bleeding of 40% BV, the CI decreased significantly compared with 20% BV in the three groups (19% in the placebo and enalaprilat groups, 14% in the valsartan group) but the MAP decreased significantly in the enalaprilat group only (23%). The SVR increased significantly in the placebo group (P<0.01 vs each of the other groups), but there were no differences in the change in SVR between the other groups.

CONCLUSION

Blockade of the renin-angiotensin system by either enalaprilat or valsartan leads to a similar decrease in arterial pressure during anaesthesia and haemorrhage but the haemodynamic profiles are quite different.

[An experience with transthoracic echocardiography after heart surgery]

OBJECTIVE

In order to determine if routine use of transthoracic echocardiography (TTE) shortly after heart surgery could have a role in postoperative management, we carried out TTE in postoperative patients operated on for CABG or valvular repair.

PATIENTS AND METHODS

For a 3 months period, we prospectively enrolled 51 patients for TTE. We performed a TTE using a Hewlett Packard Sonos 1500 and a 2.5 MHz probe. Feasibility, left ventricular kinesis, valve function, intracardiac thrombi, and pericardial effusion were noted for each patient. Patients have been divided into 2 groups: patients with or, without haemodynamic disturbance (HD, mean arterial blood pressure < or = 80 mmHg).

RESULTS

Nine TTE were impossible for bad acoustic images. Feasibility was about 82% (42 TTE/51 patients). Two ETT views were easily obtained: the apical 4-chambers (75%) and the subcostal (30%) views. TTE examination induced treatment change in 12 patients for hypovolaemia (ten patients), left ventricular dysfunction (one patient), and systolic anterior motion of mitral valve (one patient). In patients without HD (41 patients) only hypovolaemia was found (three patients) and TTE returned to normal with fluid challenge. In patients with HD (ten patients), one patient returned to the operating room for valvular replacement, one patient was treated with dobutamine for left ventricular dysfunction, seven patients with hypovolaemia recovered with fluid challenge.

CONCLUSION

TTE can guide postoperative management of patients operated on for heart surgery especially in patients with haemodynamic disturbance. Because of its safety and easiness, TTE may be the first-line examination in these patients before any invasive evaluation.

Hematologic and plasma biochemical values for Tonkean macaques (Macaca tonkeana)

Hematologic and serum biochemical parameters were measured in 29 captive Tonkean macaques (Macaca tonkeana) to provide normative reference values for the species. Mean normal values and ranges were close to those reported in other species of macaques. Some significant variations related to age and sex were found.

Contribution of nitric oxide, prostanoids and Ca(2+)-activated K+ channels to the relaxant response of bradykinin in the guinea pig bronchus in vitro

In the guinea pig bronchus with epithelium, pre-contracted with histamine, bradykinin (BK), lysyl-BK, prostaglandin E2 (PGE2), cromakalim and S-nitroso-N-acetylpenicillamine each caused graded relaxation with mean EC50s of 34 nM, 11 nM, 0.1 nM, 0.3 microM and 3.4 microM, respectively. The addition of NO synthase inhibitors N(W)-nitro-L-arginine (L-NOARG), N(G)-monomethyl-L-arginine or 7-nitroindazole reduced BK-induced relaxation by 41+/-6%, 59+/-4% and 51+/-2%, respectively. The inhibition of BK response caused by L-NOARG was completely reversed by L-, but not by D-arginine. Methylene blue and 6-(phenylamino)-5,8-quinolinedione (LY 83583) inhibited the BK response by 88+/-5% and 64+/-4%, while 1H-[1,2,4]oxadiazolo[4,3-a]quinolaxin- -one (ODQ) had no effect. However, ODQ almost abolished SNAP-induced relaxation. Indomethacin and the cyclo-oxygenase 2 (COX-2) inhibitor 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulfonyl)phenyl-2(5H)-furanon e (DFU) caused graded inhibtion of BK responses with mean IC50s of 60 nM and 0.6 nM, respectively. Addition of tetraethylammonium (TEA), charybdotoxin (ChTx), or iberotoxin (IbTx) inhibited BK-induced relaxation by 76+/-4%, 30+/-4% and 99+/-1%, respectively, but the relaxations of PGE2 and cromakalim were unaffected. In contrast, 4-aminopyridine, apamin or glibenclamide did not affect BK-induced relaxation. These results indicate that BK-induced epithelium-dependent relaxation in the guinea pig bronchus is partially mediated by release of NO or by NO-related substances, involving an activation of both cyclo-oxygenase 1 (COX-1) and COX-2 enzymes, through a cyclic guanosine monophosphate (cGMP)-independent mechanism. Furthermore, BK-induced relaxation involves an activation of high-conductance Ca(2+)-activated K+ channels highly sensitive to IbTx, and to a lesser extent to ChTx and TEA.

Mechanisms underlying the relaxation caused by the sesquiterpene polygodial in vessels from rabbit and guinea-pig

The sesquiterpene polygodial produces graded relaxation in rings of rabbit pulmonary artery or thoracic aorta and guinea-pig pulmonary artery with endothelium. In rings with rubbed endothelium its vasorelaxant action was largely reduced. The N(omega)-nitro-L-arginine (L-NOARG), N(G)-nitro-L-arginine methyl ester (L-NAME), 6-anilino-5,8-quinolinedione (LY 83583) and 1H-[1,2, 4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), inhibited the endothelium-dependent vasorelaxant action of polygodial. In contrast, N(omega)-nitro-D-arginine (D-NOARG), indomethacin, N(2)-[(4R)-4-hydroxy-1-(1methyl-1H-indol-3yl)carbonyl-L-prol yl]-N-met hyl-N-phenylmethyl-3-(2-naphthyl)-L-alaninamide (FK 888), (S)-N-methyl-N[4-(4-acetylamino-4-phenylpiperidino)-2-(3, 4-dichlorophenyl)butyl]benzamide (SR 48968), (8R,9S, 11S)-(-)-9-hydroxy-9-n-hexyloxy-carbonyl-8-methyl-2,3,9, 20-tetrahydro-8,11-epoxy-1H,8H,11H-2,7b,11a-triaqzadibenzo[a, g]cycloocta[c,d,e]-trinden-1-one (KT 5720), calcitocin gene-related peptide receptor antagonist (CGRP-(8-37), apamin, charybdotoxin and 4-aminopyridine had no effect on polygodial action. However, glibenclamide inhibited partially, but significantly, its relaxant responses. These results demonstrate that the vasorelaxation of polygodial is partly dependent on the release of nitric oxide (NO )or an NO-derived substance from the vascular endothelium through an activation of a guanylyl cyclase-dependent mechanism. Finally, results demonstrate that the polygodial vasorelaxant action is not related with the opening of potassium (K(+)) channels, release of prostacyclin, substance P, or with the activation of adenylyl cyclase-dependent mechanisms.

The release of cytochrome c from mitochondria during apoptosis of NGF-deprived sympathetic neurons is a reversible event

During apoptosis induced by various stimuli, cytochrome c is released from mitochondria into the cytosol where it participates in caspase activation. This process has been proposed to be an irreversible consequence of mitochondrial permeability transition pore opening, which leads to mitochondrial swelling and rupture of the outer mitochondrial membrane. Here we present data demonstrating that NGF-deprived sympathetic neurons protected from apoptosis by caspase inhibitors possess mitochondria which, though depleted of cytochrome c and reduced in size, remained structurally intact as viewed by electron microscopy. After re-exposure of neurons to NGF, mitochondria recovered their normal size and their cytochrome c content, by a process requiring de novo protein synthesis. Altogether, these data suggest that depletion of cytochrome c from mitochondria is a controlled process compatible with function recovery. The ability of sympathetic neurons to recover fully from trophic factor deprivation provided irreversible caspase inhibitors have been present during the insult period, has therapeutical implications for a number of acute neuropathologies.

[Heparin-induced thrombopenia]

Heparin-induced thrombocytopenia remains a topical subject for at least two reasons. The first reason is the increasing prescription of low molecular weight heparins (LMWH) rather than unfractionated heparins, with limited laboratory surveillance, raising the question concerning the need for twice-weekly platelet counts, according to the recommendations of the Vidal drug directory. The second reason is the recent release onto the market of two products, danaparoid (Orgaran) and lepirudin (Refludin) for this precise indication of heparin-induced thrombocytopenia. These products greatly facilitate the management of this complication. Many basic research teams are trying to optimize the detection of heparin-dependent antibodies and to more clearly elucidate the mechanism of this particular thrombocytopenia, which carries a risk of very severe thrombotic complications when the diagnosis is delayed.

Venous thrombosis in older people: prevalence of the factor V gene mutation Q506

OBJECTIVES

Old age is usually considered to be a risk factor for venous thromboembolism, in conjunction with other factors such as heart failure, major surgery, cancer, long-term immobilization, and antiphospholipid antibodies. Genetic risk factors, especially inherited deficiencies in coagulation inhibitors, also play a role in the pathogenesis of thrombosis, but these are usually diagnosed in thrombophilic patients before the age of 50. The factor V Q506 mutation, responsible for activated protein C resistance, was recently linked to thromboembolic disease. We therefore investigated the prevalence of biological risk factors in older hospital patients with venous thromboembolism.

DESIGN

A 2-year study period.

SETTING

Ivry sur Seine (Paris), France.

PARTICIPANTS

Seventy-nine geriatric patients (60 women and 19 men, mean age 83+/-6.8 years, range 70-102 years) who had had at least one proven episode of venous thromboembolism were enrolled over a 2-year period.

MEASUREMENTS

Lupus anticoagulant and antithrombin (AT), protein C (PC), and protein S (PS) levels were determined in plasma. The factor V Q506 mutation was detected on genomic DNA.

RESULTS

Lupus anticoagulant was detected in two women, one of whom also had a high level of anticardiolipin IgG, leading to the diagnosis of an antiphospholipid syndrome. No hereditary deficiency in AT, PC, or PS was found, but one patient had an acquired AT deficiency. Interestingly, nine of the 79 patients (11.4%, six women and three men) were heterozygous for the factor V Q506 mutation, although none were homozygous. The only major risk factor for thrombosis identified in these patients was prolonged immobilization in four cases. Four of the nine patients who were heterozygous for the factor V Q506 mutation had recurrent thromboembolism, and two of these patients had been immobilized for long periods.

CONCLUSIONS

This study confirms that hereditary deficiencies in coagulation inhibitors, and the lupus anticoagulant, are rarely involved in the pathogenesis of venous thromboembolism in older subjects. In contrast, the factor V Q506 mutation was frequently associated with thrombosis (11.4% of our patients) and should, therefore, be considered an important risk factor in the older people.

A novel isoform of the orphan nuclear receptor RORbeta is specifically expressed in pineal gland and retina

RORbeta is a member of the nuclear hormone receptor superfamily whose ligand is unknown. Expression of RORbeta is confined to the central nervous system and its pattern suggests that this orphan nuclear receptor is implicated in the processing of sensory information and in circadian timing. In rats, RORbeta mRNA levels oscillate robustly in pineal gland and retina, displaying a 24h rhythm. Here we report the cloning of the cDNA of a novel isoform of RORbeta from rat pineal tissue. Expression of this isoform, called RORbeta2, is confined to pineal gland and retina and strongly increases at night. RORbeta2 shares common DNA- and putative ligand-binding domains with the canonical RORbeta (referred to as RORbeta1), but is characterized by a different amino-terminal domain. This structural difference renders RORbeta2 much more selectively binding to DNA than RORbeta1. Moreover, in contrast to RORbeta1, the novel isoform efficiently activates transcription also in non-neuronal cell lines. Thus, the two RORbeta isoforms are likely to regulate different sets of genes in different physiological contexts. 1998 Elsevier Science B.V.

Disruption of retinoid-related orphan receptor beta changes circadian behavior, causes retinal degeneration and leads to vacillans phenotype in mice

The orphan nuclear receptor RORbeta is expressed in areas of the central nervous system which are involved in the processing of sensory information, including spinal cord, thalamus and sensory cerebellar cortices. Additionally, RORbeta localizes to the three principal anatomical components of the mammalian timing system, the suprachiasmatic nuclei, the retina and the pineal gland. RORbeta mRNA levels oscillate in retina and pineal gland with a circadian rhythm that persists in constant darkness. RORbeta-/- mice display a duck-like gait, transient male incapability to sexually reproduce, and a severely disorganized retina that suffers from postnatal degeneration. Consequently, adult RORbeta-/- mice are blind, yet their circadian activity rhythm is still entrained by light-dark cycles. Interestingly, under conditions of constant darkness, RORbeta-/- mice display an extended period of free-running rhythmicity. The overall behavioral phenotype of RORbeta-/- mice, together with the chromosomal localization of the RORbeta gene, suggests a close relationship to the spontaneous mouse mutation vacillans described >40 years ago.

staggerer phenotype in retinoid-related orphan receptor alpha-deficient mice

Retinoid-related orphan receptor alpha (RORalpha) is a member of the nuclear receptor superfamily. To study its physiological role we generated null-mutant mice by targeted insertion of a lacZ reporter gene encoding the enzyme beta-galactosidase. In heterozygous RORalpha+/- mice we found beta-galactosidase activity, indicative of RORalpha protein expression, confined to the central nervous system, skin and testis. In the central nervous system, the RORalpha gene is expressed in cerebellar Purkinje cells, the thalamus, the suprachiasmatic nuclei, and retinal ganglion cells. In skin, RORalpha is strongly expressed in the hair follicle, the epidermis, and the sebaceous gland. Finally, the peritubular cells of the testis and the epithelial cells of the epididymis also strongly express RORalpha. Recently, it was reported that the ataxic mouse mutant staggerer (sg/sg) is caused by a deletion in the RORalpha gene. The analysis of the cerebellar and the behavioral phenotype of homozygous RORalpha-/- mice proves identity to sg/sg mice. Although the absence of RORalpha causes dramatic developmental effects in the cerebellum, it has no apparent morphological effect on thalamus, hypothalamus, and retina. Similarly, testis and skin of RORalpha-/- mice display a normal phenotype. However, the pelage hair of both sg/sg and RORalpha-/- is significantly less dense and when shaved shows reluctance to regrow.

[Murine typhus in Portugal]

Murine typhus or endemic typhus is a wide spread infectious disease, with a low prevalence in developed countries, but surely underdiagnosed. Its relative benignity, the similarity to other infectious diseases and the discretion of its epidemiologic chain, as well as the usual unexpectedness of its existence, makes its diagnosis more difficult. The clinical presentation and evolution of this case illustrate the necessity of being aware of this nosological entity.

The expression pattern of the orphan nuclear receptor RORbeta in the developing and adult rat nervous system suggests a role in the processing of sensory information and in circadian rhythm

RORbeta is an orphan nuclear receptor related to retinoid and thyroid hormone receptors and is exclusively expressed in the central nervous system (CNS). Here we present an in situ hybridization analysis of the distribution of RORbeta mRNA in the developing and adult rat CNS. The receptor localizes to areas involved in the processing of sensory information. In the cerebral cortex, RORbeta mRNA was exclusively detected in non-pyramidal neurons of layer IV and, less so, layer V. The highest expression was found in primary sensory cortices. In the thalamus highest RORbeta expression was found in the sensory relay nuclei projecting to the respective cortical areas. In contrast, sensory projection neurons in the periphery, for example retinal ganglion cells and neurons of the sensory ganglia showed only little RORbeta expression. RORbeta is also expressed in areas involved in the generation and maintenance of circadian rhythms - the suprachiasmatic nucleus, the pineal gland and the retina. In the latter two tissues, RORbeta mRNA abundance oscillates with circadian rhythmicity peaking during the hours of darkness. RORbeta mRNA could not be detected in striatum, hippocampus, cerebellum, the motor nuclei of the cranial nerves or the ventral part of the spinal cord. During development, RORbeta is expressed in many areas as early as embryonic day (E) 15, anticipating the distribution pattern in the adult. Our data suggest that RORbeta regulates genes whose products play essential roles in the context of sensory input integration as well as in the context of circadian timing system.

The pig as a model in liver xenotransplantation

Xenotransplantation is considered to be the best solution to the critical shortage of human donors. Despite its phylogenetic distance, the pig appears to be the most appropriate source of organs for transplantation in humans. Its anatomy and physiology are similar to that of man, it can be raised in specific pathogen free environments and it is available in large quantities. The immunological barrier remains to be overcome, however. Considerable progress in the pathogeny of xenogenic rejection has led to the development of therapeutic strategies and the prospect of clinical xenografting appears realisable in the near future.

The metastasis suppressor candidate nucleotide diphosphate kinase NM23 specifically interacts with members of the ROR/RZR nuclear orphan receptor subfamily

We have cloned proteins that interact with the nuclear orphan receptor RZR beta using the yeast two-hybrid system. We identified, amongst a number of other genes, the nucleoside diphosphate kinase (NDPK)-2 also known as Nm23-2, c-myc regulatory factor PuF and differentiation inhibitory factor, RZR beta specifically interacts with Nm23-2 but not with the closely related tumor metastasis suppressor candidate gene product Nm23-1. In contrast ROR alpha interacts with both Nm23 proteins. These findings were corroborated by in vitro interaction assays based on GST-pulldown experiments. With-n-myc we propose a candidate gene regulated by ROR alpha/RZR beta and Nm23, based on the finding that the respective DNA binding sites in the first intron are conserved in several mammalian species.

In vitro interleukin-1 and 2 production and interleukin 2 receptor expression in the rhesus monkey

Anti-human monoclonal antibodies were used to detect and quantify interleukins-1 and 2 and interleukin-2 receptor expression in peripheral blood mononuclear cells from a rhesus monkey. Interleukin-1 production could be induced by phorbol esters (PMA) and was potentiated by phytohemagglutinin (PHA). Interleukin-2 secretion could also be induced by the combination of PHA and PMA, but only weakly with PHA alone. Interleukin-2 receptor expression was present in a subpopulation of unstimulated lymphocytes and could be enhanced by PHA or PMA. These data show once again that the rhesus monkey immune system is cross-reactive with the human one and that rhesus macaque could be a good model to study interleukin therapy.