Coûts des hospitalisations et des soins de suite et de réadaptation liés au COVID-19 en France en 2020

Introduction

A l'origine d'une pandémie depuis 2020, la maladie liée au coronavirus SARS-CoV-2 (COVID-19) représente une surcharge importante pour les systèmes de santé. La surveillance nationale a dénombré un total de 261 123 cas d'infection ayant nécessité une hospitalisation en 2020 et 64 078 décès. Cette étude a pour objectif d'estimer la charge économique des hospitalisations, des soins de suite et de réadaptation (SSR) et des hospitalisations à domicile (HAD) liée au COVID-19 en France en 2020.

Matériels et méthodes

Une cohorte rétrospective incluant tous les patients hospitalisés avec un code diagnostic (CIM-10 ; principal, secondaire ou associé) relatif au COVID-19 entre le 1er janvier et le 31 décembre 2020 a été conduite à partir des données du PMSI (Programme de médicalisation des systèmes d'information : MCO, SSR et HAD). Les patients ont été divisés en 3 groupes selon les définitions de Santé Publique France : cas confirmés (virus identifié et symptômes typiques : code U07.10 ou U07.14), probables (symptômes cliniques U07.11) et possibles (autres symptômes U07.15). L'évaluation et la valorisation des coûts directs ont été effectuées selon la tarification à l'activité et les suppléments applicables de l'assurance maladie.

Résultats

Les données du PMSI ont permis d'identifier 271 728 séjours pour 210 635 patients hospitalisés avec un lien avec le COVID-19 dont 185 111 cas confirmés, 23 416 probables et 2 108 possibles. Les résultats suivants correspondent aux cas confirmés. La majorité des patients (85 %, N = 157 758) ont été pris en charge initialement par un séjour en MCO, 10 % (N = 18 375) en SSR et 5 % (N = 8 978) en HAD. La durée moyenne de séjour était de 17,8 ± 22 jours au total, 12,7 ± 13 jours en MCO, 26,4 ± 26 jours en SSR et 15,5 ± 19 jours en HAD. Parmi les séjours, 23 % ont impliqués les soins critiques (réanimation, unité de soins intensifs et/ou surveillance continue). La moitié des cas était des hommes, dont 56 % hospitalisés en MCO (N = 88 310), 39 % en SSR (N = 7 189) et 31 % en HAD (N = 2801). Au moins une comorbidité était enregistrée chez 79 % des patients (N = 146 457) : hypertension (54 %), diabète (27 %), troubles cardiovasculaires (24 %), insuffisance cardiaque (19 %), obésité (22 %), insuffisance rénale (16 %) et cancer (18 %).

Le coût total des hospitalisations et des SSR liés aux cas confirmés de COVID-19 est estimé à 1,672 milliards € représentant une moyenne de 7 044 €/séjour. Pour les passages en soins critiques, on estime à 339 millions € pour le passage en réanimation, 21,5 millions € en soins intensifs et 28,3 millions € en surveillance continue (respectivement 12 761 €, 2 356 € et 2 248 € en moyenne par séjour). Enfin, 11,5 millions € étaient attribuables à des traitements et/ou dispositifs inscrits sur la liste en sus.

Conclusion

Ces données quantifient le coût de la prise en charge hospitalière du COVID-19 en France en 2020, notamment à travers la durée de séjour et le recours aux soins intensifs pour un quart des patients. Cette surcharge économique devrait être réduite avec la mise en place de la couverture vaccinale en 2021.

Liens d'intérêts déclarés

Pr Sébastien Gallien : membre du comité scientifique de cette étude, qui est financée par Janssen-cilag France

[Pathological nighttime fears in children: Clinical specificities and effective therapeutics]

OBJECTIVE

Pathological nighttime fears in children have been little studied. However, this disorder is commonly encountered in medical consultations and is discomforting and dysfunctional for both the child and the family. Most nighttime fears are part and parcel of normal development, and emanate from increasingly sophisticated cognitive development in the growing child. Thus, most children report a variety of coping strategies generally helpful in reducing their anxiety, which resolves spontaneously in the growing child. Nevertheless, in about 10% of children, nighttime fears are related to one or more anxiety disorders according to Diagnostic and Statistical Manual of Mental Disorders criteria. Then, it is estimated that severe nighttime fears and sleep problems occur in 20-30% of children. This problem is not transient and has to be treated. This study aims to review clinical features of nighttime fears and possible treatments for these patients and their families.

METHOD

This systematic review follows the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement guidelines. Two databases (Medline and Web of Science) were searched combining the search terms: nighttime fears AND children. English and French languages were imposed. There were no publication date or publication status limitations.

RESULTS

Pathological nighttime fears are responsible for emotional (crying, panic, tantrums at bedtime, loss of confidence, self-disparaging negative statements, and feeling of social embarrassment) and behavioral (wandering alone in the house at night, calls for parental or sibling comfort, bed sharing with parents or siblings, light source at night, refusal to go to the toilet alone at night) disturbances. This leads to a poor quality of sleep interfering with school learning, and also affects social development and family functioning. A full assessment has to be made to eliminate organic causes, have a baseline functioning, and search for comorbid anxiety diseases. The treatments which have proved effective are some cognitive-behavioral techniques: systematic desensitization (with relaxation or emotive imagery), reinforcement (gain of points and techniques of self statement), and cognitive techniques (reinforcing self-statements, reducing the aversive aspects of being in the dark, involving reality-testing statements, and active control are preferred in children older than 6 years, whereas the "anti-monster letter" and the techniques using a doll are preferred in children under 6 years old). The modelling technique seems to be appropriate at any age.

CONCLUSION

We have explained the clinical features of pathological nighttime fears and the way to assess this disease, and we have pointed out the treatments whose effectiveness has been evaluated in this indication.

Myocilin protein levels in the aqueous humor of the glaucomas in selected canine breeds

OBJECTIVE

To compare aqueous humor myocilin protein levels in dogs with the primary glaucomas to those with the secondary glaucomas, primary cataracts, and diabetic cataracts.

MATERIALS AND METHODS

Four groups were selected, based on diagnosis by the attending veterinary ophthalmologists and included: primary glaucoma (primary open-angle glaucoma (POAG) and primary closed angle glaucoma (PCAG); n = 155); secondary glaucoma (n = 94); primary (presumed inherited) cataract (n = 142), and diabetic cataract (n = 83). A total of 474 samples (187 males, 263 females, 24 unreported) with average ages of 117 months for the males and 101 months for the females were analyzed. Myocilin protein was measured using the Coomassie staining and Western blot methods relative to a myocilin control.

RESULTS

Differences were seen between nonglaucomatous (cataractous) and glaucomatous dogs with myocilin levels in glaucomatous eyes being many times higher than those in the cataractous dogs. Primary glaucomatous dogs were found to have an aqueous humor myocilin protein level of 17.30 +/- 1.03 units. Secondary glaucomas had the highest level of myocilin in the aqueous humor with 19.27 +/- 1.41 units. Diabetic cataractous dogs had the lowest levels of myocilin reported with 6.60 +/- 0.88 (mean +/- SEM) units. Normal (cataractous) dogs had a myocilin level in the aqueous humor of 8.05 +/- 0.86 units.

CONCLUSION

Aqueous humor protein levels were elevated, relative to the myocilin control, in both the primary and secondary glaucoma groups compared to the cataract and diabetic cataract groups. Like in the Beagle POAG, aqueous humor myocilin protein levels are increased. Further studies are indicated to investigate the exact role of the aqueous humor myocilin protein in the genesis in increased IOP in these primary glaucomatous breeds.

Antiviral responses of human Leydig cells to mumps virus infection or poly I:C stimulation

BACKGROUND

The immuno-privileged status of the testis is essential to the maintenance of its functions, and innate immunity is likely to play a key role in limiting harmful viral infections, as demonstrated in the rat. In men mumps virus infects Leydig cells and has deleterious effects on testosterone production and spermatogenesis. The aim of this study was to test whether mumps virus infection of isolated human Leydig cells was associated with an inhibition of their innate antiviral defences.

METHODS

Leydig cell production of mRNA and protein for interferons (IFNs) and of three antiviral proteins—2′5′ oligoadenylate synthetase (2′5′OAS), double-stranded RNA-activated protein kinase (PKR) and MxA—was investigated, in the absence or presence of mumps virus or viral stimuli including poly I:C, a mimetic of RNA viruses replication product.

RESULTS

Stimulated or not, human Leydig cells appeared unable to produce routinely detectable IFNs α, β and γ. Although the level of PKR remained unchanged after stimulation, the expression of 2′5′OAS and MxA was enhanced following either mumps virus or poly I:C exposure (P < 0.05 versus control).

CONCLUSIONS

Overall, our results demonstrate that mumps virus replication in human Leydig cells is not associated with a specific inhibition of IFNs or 2′5′OAS, MxA and PKR production and that these cells display relatively weak endogenous antiviral abilities, as opposed to their rat counterparts.

Human testis in organotypic culture: application for basic or clinical research

BACKGROUND

Over recent decades, recurring efforts have been devoted to developing testicular cell or tissue cultures for basic and clinical research. However, there remains much confusion, particularly concerning the fate of human germ cells in culture.

OBJECTIVE

To reassess the status of human testicular cell types as well as the ability of germ cells to divide and differentiate in organotypic culture.

METHODS

Human testicular fragments were maintained for 2 weeks in culture. The viability and functionality of testicular cells were assessed using light and electronic microscopy, apoptotic cell labelling, 5-bromo-2'-deoxyuridine (BrdU) incorporation, immunohistochemistry and quantitative PCR against specific cell markers.

RESULTS

A gradual loss of meiotic and post-meiotic germ cells occurred throughout the culture period, irrespective of the presence of gonadotrophins. However, all germ cell types remained traceable for up to 16 days, some still dividing and differentiating at a rate compatible with the in vivo situation. Good maintenance of the general architecture of the explants associated with clearly quantifiable levels of several somatic cell markers was observed.

CONCLUSION

Although this culture model is clearly unsuitable for preparing germ cells for therapeutic purposes, it does represent a most valuable tool for testing the effects of biological and chemical agents on testicular tissue.

[Children in single-parent families, yesterday and today]

"This study, conducted from the point of view of the children, compares cohorts from the time of New France [Quebec] with those of Canada today, showing that single parenthood is not a new phenomenon. The types of single parenthood, however, are quite different. The colonial model of the traditional family has given way to a variety of family situations. As well, while death was the only cause of single parenthood during the colonial era, separations today are essentially based on some sort of decision. The psychological repercussions of losing a parent are thus completely different." (SUMMARY IN ENG AND SPA)

Managing disasters involving hazardous substances in Canada: technical and sociopolitical issues

This article focuses on the management lessons learned from disasters involving hazardous materials, which occurred in Quebec, Canada, between 1988 and 1995. The findings of the previous case studies of Canadian and some other disasters are considered as well. Both technical and sociopolitical issues on the disaster management are contemplated from the viewpoint of complexity and uncertainty. A distinction is made between the two concepts through specific examples. In addition, two types of uncertainty, first and second-level, are differentiated. The relationship between technical and sociopolitical issues of such management are then illustrated, and the salience of efficient disaster risk communication between technical specialists and the public for bridging the gap existing between these two types of issues is shown.

Rose bengal positive epithelial microerosions as a manifestation of equine keratomycosis

Purpose To describe the clinical appearance of corneal epithelial cell microerosions associated with keratomycosis in the horse. METHODS: Retrospective clinical study. RESULTS: Multifocal, punctate, superficial corneal opacities with positive rose bengal retention were noted in six horses with presumed 'viral keratitis'. Faint fluorescein staining was also present in three cases. Equine herpesvirus tissue culture inoculation was negative for a cytopathic effect in three cases. Aspergillus (n = 3), Curvularia (n = 1), and an unidentified fungus (n = 1) were cultured in five horses, and hyphae found on corneal cytology from the sixth. Mixed bacterial infections were present in three eyes. The eyes of two horses with Aspergillus progressed to deep melting corneal ulcers that required surgical therapy. The microerosions remained superficial, but persistent in the other four eyes. Natamycin was utilized topically in all six horses. Transmission electron microscopy from case 6 revealed mucin layer disruption, an intact corneal epithelial cell layer, and fungal attachment to degenerating epithelial cells. The visual outcome was positive in all six horses, although healing was prolonged (48.5 +/- 14.5 days on average in the horses with no surgery; 62 days on average in the two horses that required surgery). CONCLUSIONS: Complete removal or full-thickness penetration of the corneal epithelial cell barrier may not be necessary to allow fungal adherence and initiation of keratomycosis in the horse. Prior to colonization and invasion of the horse cornea, fungi may induce changes in the mucin layer of the tear film that result in or are associated with rose bengal positive microerosions of the superficial corneal epithelium. Horses with painful eyes, and eyes with superficial, multifocal corneal opacities should have their corneas stained with both fluorescein and rose bengal as fungal microerosions may stain weakly, or not at all, with fluorescein, and may thus be mistaken for presumed 'viral keratitis' of the horse.

Differential expression of nucleoside diphosphate kinases (NDPK/NM23) during Xenopus early development

In Xenopus laevis, three nucleoside diphosphate kinase (NDPK) monomers have been described (NDPK X1, X2 and X3) (Ouatas et al., 1997). In eucaryotes, this kinase is known as a hetero- or homohexamer. Here, we examine the distribution of the enzyme and its different subunit mRNAs during oogenesis and early embryogenesis of Xenopus laevis, respectively by immunohistofluorescence and whole-mount in situ hybridization. These analyses show that NDPKs and their mRNAs are differentially distributed throughout the oocyte and early embryos with a high level of transcription in somites and brain. We emphasize two points. First, each mRNA displays a distinct subcellular localization in somites, suggesting a complex regulation of NDPK genes both at the transcriptional and translational level and a possible involvement of NDPK X2 homohexamers in the dorsal muscle differentiation. Second, in oocytes and early embryos, the proteins are mainly localized in the nucleus, suggesting a new mechanism for their nuclear import, since they do not possess any known nuclear import sequences.

Thyroid hormone regulation of germ cell-specific EF-1 alpha expression during metamorphosis of Xenopus laevis

In situ hybridization was used to follow the distribution of the mRNAs encoding the somatic form of elongation factor 1 alpha (EF-1 alpha S) and the germinal counterparts of this factor, thesaurin a and EF-1 alpha O, throughout metamorphosis in the gonads of Xenopus laevis tadpoles. EF-1 alpha S mRNA is detected before metamorphosis in both the somatic and germ cells of the gonads. In contrast, thesaurin a and EF-1 alpha O mRNAs are first detected in spermatogonia and oogonia at stages 60-62, corresponding to the climax of metamorphosis and to the peak of circulating thyroid hormone. To determine whether thyroid hormone, the instigator of metamorphosis, is involved in regulating the expression of the germinal gene EF-1 alpha O, Xenopus XTC cells were transfected with an EF-1 alpha O promoter sequence inserted in front of the luciferase reporter gene. Addition of T3 to the cell culture medium induced a dose-dependent increase in transcription from the EF-1 alpha O promoter. This effect was enhanced when the construct was cotransfected with an expression vector for a Xenopus thyroid hormone receptor. Our data show that germ cells switch from a somatic to a germ-cell specific mode of expression during metamorphosis. Furthermore, this switch appears to be induced by thyroid hormone.

A parallel between development and evolution: germ cell recruitment by the gonads

In gonad-bearing animals gametogenesis can be divided into three main phases. During embryonic development the primordial germ cells move towards the gonadal primordia. A long, intra-gonadal phase follows during which the germ cells grow and differentiate. Mature germ cells are finally released from the gonads and brought to the exterior. Thus, germ cells are successively motile, non-motile and motile again. This complex life history is given here a simple evolutionary interpretation. The basic assumption is that primitive Metazoa already had germ cells, but no gonads to harbour them. Higher animals acquired gonads, which sequestered the germ cells, thus creating the temporary confinement experienced by germ cells in most present-day Metazoa. This evolutionary scheme may explain why several steps of germ cell differentiation are totally or partially independent of the gonads. These steps presumably existed in primitive, gonad-free Metazoa, and conserved their autonomy in higher animals.

The dichotomy between germ line and somatic line, and the origin of cell mortality

The germ cells of extant animals are potentially immortal, whereas somatic cells are mortal, that is, they are able to carry out only a finite number of divisions. In this article we propose an evolutionary interpretation of these differences. We assume that germ cells of the earliest metazoans inherited immortality from their unicellular ancestor, while somatic cells acquired mortality by gaining new functions. It follows that cell mortality was under genetic control from the beginning of metazoan life.

mRNP4, a major mRNA-binding protein from Xenopus oocytes is identical to transcription factor FRG Y2

Previous work has revealed a striking similarity between the sequence of mRNP4, a major mRNA-binding protein of Xenopus laevis oocytes and FRG Y2, a transcription factor specific for Y-box-containing promoters. However, the apparent molecular mass of mRNP4 exceeds by 50-60% the cDNA-deduced molecular mass of FRG Y2. To resolve this discrepancy we have measured the real molecular mass of mRNP4 by sedimentation equilibrium. The molecular mass of mRNP4 closely agrees with that of FRG Y2. We conclude that mRNP4 is identical to FRG Y2 and has a dual function in oocytes. As a DNA-binding protein, mRNP4 stimulates transcription from a specific set of promoters. As a mRNA-binding protein, mRNP4 favors accumulation of the transcripts it contributes to produce.

The genes encoding the major 42S storage particle proteins are expressed in male and female germ cells of Xenopus laevis

As components of the 42S storage particles (thesaurisomes), thesaurin a and thesaurin b are involved in the long-term storage of tRNA and 5S RNA in previtellogenic oocytes of Xenopus laevis. Thesaurin a and thesaurin b are among the most abundant proteins in previtellogenic oocytes. We show here that the mRNAs encoding thesaurin a and thesaurin b are present not only in previtellogenic oocytes but also in pre-meiotic germ cells (oogonia). These mRNAs can also be detected in spermatogonia and early spermatocytes, and are translated into protein in testis, as they are in ovary. We conclude that male germ cells mimic female germ cells in several aspects of gene activity related to RNA accumulation and metabolism.

Germ cell-specific expression of a gene encoding eukaryotic translation elongation factor 1 alpha (eEF-1 alpha) and generation of eEF-1 alpha retropseudogenes in Xenopus laevis

We have studied by in situ hybridization the expression of the genes encoding the somatic form and the oocyte form of Xenopus laevis eEF-1 alpha. The somatic form of eEF-1 alpha (eEF-1 alpha S) mRNA is virtually undetectable in male and female germ cells of the adult gonad but is very abundant in embryonic cells after the neurula stage. In contrast, another form of eEF-1 alpha (eEF-1 alpha O) mRNA is highly concentrated in oogonia and in previtellogenic oocytes but is undetectable in eggs and embryos. eEF-1 alpha O mRNA is also present in spermatogonia and spermatocytes of adult testis. The latter finding identifies eEF-1 alpha O mRNA as a germ cell-specific gene product. Although germ cells contain very little eEF-1 alpha S mRNA, several eEF-1 alpha S retropseudogenes exist in X. laevis chromosomes. These genes are thought to arise in germ cells from reverse transcription of mRNA and subsequent integration of the cDNA copies into chromosomal DNA. We suggest that eEF-1 alpha S pseudogenes are generated in primordial germ cells of the embryo before they differentiate into oogonia or spermatogonia.

Two forms of elongation factor 1 alpha (EF-1 alpha O and 42Sp50), present in oocytes, but absent in somatic cells of Xenopus laevis

We have purified and partially sequenced the EF-1 alpha protein from Xenopus laevis oocytes (EF-1 alpha O). We show that the two cDNA clones isolated by Coppared et al. (Coppard, N. J., K. Poulsen, H. O. Madsen, J. Frydenberg, and B. F. C. Clark. 1991. J. Cell Biol. 112:237-243) do not encode 42Sp50, as claimed by these authors, but two very similar forms of EF-1 alpha O (EF-1 alpha O and EF-1 alpha O1). 42Sp50 is the major protein component of a 42S nucleoprotein particle that is very abundant in previtellogenic oocytes of X. laevis, 42Sp50 differs from EF-1 alpha O not only by its amino acid sequence, but also by several properties already reported. In particular, 42Sp50 has a low EF-1 alpha activity. It is distributed uniformly in the cytoplasm of previtellogenic oocytes, in contrast to EF-1 alpha O which is concentrated in a small region of the cytoplasm, known as the mitochondrial mass or Balbiani body.

Purification and characterization of a germ cell-specific form of elongation factor 1 alpha (EF-1 alpha) from Xenopus laevis

Elongation factor 1 alpha (EF-1 alpha) was purified to homogeneity from full-grown oocytes of Xenopus laevis. This protein is encoded by a gene previously shown to be expressed in male and female germ cells, and repressed in somatic cells. The purified protein was identified with EF-1 alpha on criteria of molecular mass, cross-reaction with antibodies raised against Artemia salina EF-1 alpha, affinity for guanine nucleotides, and ability to promote the mRNA-dependent binding of aminoacyl tRNA to 80S ribosomes.

Structural and functional properties of thesaurin a (42Sp50), the major protein of the 42 S particles present in Xenopus laevis previtellogenic oocytes

Thesaurin a is one of two protein components of a 42 S ribonucleoprotein particle that is very abundant in previtellogenic oocytes of Xenopus laevis. The primary function of the 42 S particle is the long-term storage of 5 S RNA and aminoacyl-tRNA. Thesaurin a is homologous to eukaryotic elongation factor 1 alpha (EF-1 alpha) and to prokaryotic elongation factor Tu (EF-Tu). Sequence comparison with EF-1 alpha and EF-Tu of different species indicates that thesaurin a is rather distantly related to all eukaryotic elongation factors. In spite of this, the secondary structure of thesaurin a, deduced from hydrophobic cluster analysis, is remarkably similar to that of EF-1 alpha and EF-Tu. The binding and catalytic properties of thesaurin a are also similar but not identical to those of EF-1 alpha. Like EF-1 alpha, purified thesaurin a binds tRNA, GDP, and GTP. Unlike EF-1 alpha, thesaurin a binds discharged tRNA more tightly than charged tRNA, and GTP more tightly than GDP. Thesaurin a also hydrolyzes GTP and catalyzes the mRNA-dependent binding of aminoacyl-tRNA to 80 S ribosomes. The functional properties of the 42 S particle are in general agreement with those of purified thesaurin a. In particular, the 42 S particle contains GTP and efficiently transfers aminoacyl-tRNA to 80 S ribosomes without addition of exogenous elongation factor.

Purification of two thermostable components of messenger ribonucleoprotein particles (mRNPs) from Xenopus laevis oocytes, belonging to a novel class of RNA-binding proteins

We have purified and partially sequenced two proteins from Xenopus laevis previtellogenic oocytes, belonging to messenger ribonucleoprotein particles (mRNPs). The purification procedure rests on the thermostability of these proteins, which remain soluble after heating the cell extracts at 80 degrees C. The thermostable proteins can be identified with two of the most abundant components (mRNP3 and mRNP4) of the mRNPs, described by Darnbrough and Ford (1981) [Eur. J. Biochem. 118, 415-424]. mRNP3 and mRNP4 are homologous to each other, but to no other protein of known sequence. The abundance and semi-periodic distribution of proline residues in mRNP3 and mRNP4 sequences suggest that these RNA-binding proteins adopt an unusual type of conformation.

Elongation factor 1 alpha (EF-1 alpha) is concentrated in the Balbiani body and accumulates coordinately with the ribosomes during oogenesis of Xenopus laevis

In Xenopus laevis oocytes two distinct systems catalyze the mRNA-dependent binding of aminoacyl tRNA to the A site of ribosomes. These systems are elongation factor 1 alpha (EF-1 alpha) and the 42S nucleoprotein particle. This particle is also implicated in the long-term storage of 5S RNA and aminoacyl tRNA during early oogenesis. We report here that the ribosomes and the storage particles are distributed uniformly in the cytoplasm of previtellogenic (stage I) oocytes. In contrast, EF-1 alpha is concentrated in a small region of the cytoplasm, known as the mitochondrial mass or Balbiani body. When the Balbiani body disperses in early vitellogenic oocytes (stage II), EF-1 alpha becomes evenly distributed in the cytoplasm. The main phase of EF-1 alpha accumulation follows the disappearance of the 42S particles (stage II), but coincides with the main phase of ribosome accumulation (stages III and IV).

Three genes under different developmental control encode elongation factor 1-alpha in Xenopus laevis

We have cloned cDNAs encoding two variants of the elongation factor for protein synthesis in Xenopus laevis, called EF-1 alpha. One of these (42Sp50) is expressed exclusively in immature oocytes. It is one of two protein components of a 42S RNP particle that is very abundant in previtellogenic oocytes. The 42S RNP particle consists of various tRNAs, 5S RNA, 42Sp50 and a 5S RNA binding protein (42Sp43). A major function served by 42Sp50 appears to be the storage of tRNAs for later use in oogenesis and early embryogenesis. The second EF-1 alpha variant (EF-1 alpha O) is expressed mainly in oocytes but transiently in early embryogenesis as well. Its mRNA cannot be detected after neurulation in somatic cells. EF-1 alpha O is closely related to a third EF-1 alpha (EF-1 alpha S), discovered originally by Krieg et al. (1). EF-1 alpha S is expressed at low levels in oocytes but actively in somatic cells. The latter two proteins are very similar to known eukaryotic EF-1 alpha from other organisms and presumably function in their respective cell types to support protein synthesis.

The effect of nortriptyline-specific active immunization on amitriptyline toxicity and disposition in the rabbit

Rabbits were actively immunized by a conjugate of nortriptyline (NT) to study the effect of specific anti-NT antibodies on toxicity and disposition of amitriptyline (AT). Control and immunized rabbits received 115 mg/kg AT intraperitoneally (i.p.). The lethality dose (LD) profile exhibited a gentle slope; LD100 and LD0 were separated by 100 mg/kg. Mortality was significantly reduced from LD67 to LD43 (P less than 0.05). Total plasma concentrations of the toxin were increased in the immunized group compared to the control group. AUC0.5-24 h value was 5-fold higher in the immunized group than in the control group. Moreover, a smaller fraction of unbound toxin in plasma was observed in the immunized group than in the control group. These observations indicate that AT was actively sequestered by antibodies. The intensity of this phenomenon was a function of both the antibody affinity constant (10(9) M-1) and the neutralizing capacity (varying from 0.005 to 0.2 mg/kg) of the circulating antibodies in each immunized rabbit. Results clearly show that anti-NT antibodies are able to effectively sequestrate AT.

Biochemical research on oogenesis. RNA accumulation in the oocytes of the newt Pleurodeles waltl

We have compared the accumulation of 5S RNA and tRNA in oocytes of Pleurodeles waltl with the corresponding process previously studied in Xenopus laevis. 5S RNA synthesis is regulated similarly in both species since different families of 5S RNA genes are transcribed in oocytes and in somatic cells of P. waltl, as in those of X. laevis. Previtellogenic oocytes of P. waltl contain only one prominent kind of storage particles (thesaurisomes). In contrast, X. laevis oocytes of the same size contain two major classes of thesaurisomes, sedimenting at 42S and 7S. The more abundant particles found in P. waltl oocytes are homologous to the larger thesaurisomes (42S) of X. laevis, but they have a lower sedimentation coefficient and a higher tRNA/5S RNA molar ratio than their X. laevis counterparts. Small amounts of particles which we think to be homologous to the 7S particles of X. laevis are present in previtellogenic oocytes of P. waltl. Therefore, the storage function of the 7S particle protein (TFIIIA) is only marginal in this species. In X. laevis oocytes TFIIIA has a second function. It acts as a positive transcription factor involved in the developmentally regulated expression of the 5S RNA genes. In X. laevis expression of the oocyte-type 5S RNA genes is accompanied by a massive accumulation of TFIIIA. This is not the case in P. waltl.

Immunotoxicotherapy: present status and future trends

Immunotoxicotherapy (ITT) is currently used in humans for the treatment of snake venom and cardiac glycoside poisoning. Other toxins have been studied in animals or in vitro to assess their suitability as candidates for detoxification by specific antibodies. Testing conditions are often empirical suggesting that numerous improvements need to be introduced in ITT. Basic mechanisms in ITT include three phases: sequestration, extraction and elimination. The pharmacokinetics of these three phases depend on the type of antidotal binding site (ABS). IgG or its Fab2, Fab or Fv fragment are the possible choices. The Fab fragment is the most frequently used ABS because of its diffusion properties in the peripheral compartments and its renal excretion by glomerular filtration. Toxicokinetic and pharmacokinetic considerations indicate that the dosage cannot be satisfactorily calculated from stoichiometric principles. Study of the toxin dose-lethality curves shows that ABS dosage can be lowered. Moreover, clinical data reveal that some FAb fragments are directly eliminated without acting on toxin molecules. In order to counteract these drawbacks, a compromise between dosage and duration of infusion is suggested. Other improvements will stem from advances in immunologic methodology. Monoclonal and chimeric antibodies are new tools that will help resolve the clinical problems of immunogenicity and adverse reactions associated with polyclonal ABS.

Characterization by human antibodies of two HeLa cell proteins which are related to Xenopus laevis transcription factor TFIIIA

The sera of two patients with autoimmune disorders recognize in HeLa cell extracts two proteins with apparent molecular masses of 37,000 (p37) daltons and 32,000 daltons (p32). These proteins are non covalently associated with 5S RNA and sediment as 7-10 S particles in sucrose density gradients. Both proteins are antigenetically related to TFIIIA, a previously described protein of Xenopus laevis, which is known as a 5S RNA transcription factor and occurs in oocytes as a noncovalent complex with 5S RNA. Like TFIIIA, HeLa cell proteins p37 binds in vitro to 5S RNA and to cloned 5S RNA genes. These results suggest that protein p37 fulfils in HeLa cells a function similar to that of TFIIIA in amphibian oocytes, ie control of 5S RNA transcription.

Thesaurin a, the major protein of Xenopus laevis previtellogenic oocytes, present in the 42 S particles, is homologous to elongation factor EF-1 alpha

We have purified in SDS X.laevis thesaurin a (Mr 50,000) which is part of the 42 S storage particles. Its N-terminal amino acid is blocked and several peptides obtained by V8 protease treatment were purified and sequenced. As expected from one of the functional roles of the 42 S particles (tRNA binding, protection against deacylation and exchange with the ribosome), the amino acid sequence of thesaurin a was found to be closely related to that of the elongation factor EF-1 alpha. We suggest that all three proteins involved in 5 S RNA and tRNA storage in previtellogenic oocytes, TFIIIA, thesaurin a and thesaurin b, have a dual function: storage and a role in transcription or in protein synthesis.

Biochemical research on oogenesis: protein synthesis in whole cells and in cell-free extracts of Xenopus laevis immature ovaries

Nearly all tRNA molecules in previtellogenic oocytes of Xenopus laevis are included in nucleoprotein particles sedimenting at 42S. The tRNA-binding sites of these particles have several properties in common with those of the ribosomes. This suggests that the 42S particles might behave like unprogrammed ribosomes and be the site of a template-independent polymerization of amino acids. We expected this reaction to be insensitive to protein synthesis inhibitors, such as cycloheximide and puromycin. We found that these antibiotics almost completely inhibit the incorporation of labeled amino acids into protein, when added to the incubation medium of whole ovaries or free oocytes. In cell-free extracts of ovaries, the incorporation of amino acids is partially insensitive to cycloheximide and puromycin. When such extracts are fractionated by sucrose density centrifugation and incubated with ATP, a major peak of amino acid incorporation can be detected, which nearly coincides with the 42S particle peak.

Biochemical research on oogenesis: distribution of tRNA-linked peptides and proteins in previtellogenic oocytes of Xenopus laevis

Peptides and proteins were detected in the deacylation products of tRNA purified from the 42S particles and from the messenger ribonucleoprotein particles (mRNPs) present in the previtellogenic oocytes of Xenopus laevis. Only a small fraction of particle tRNA carries a peptide or protein chain. The bulk of particle tRNA is simply aminoacylated. The tRNA-linked peptide chains of the particles appear to turn over more slowly in vivo than aminoacyl tRNA. These chains could arise in the particles by a peptidyl transfer reaction similar to that carried out by the ribosome.

Biochemical research on oogenesis: protein synthesis by purified 42S particles from Xenopus laevis and Tinca tinca previtellogenic oocytes

When incubated with ATP and a labeled amino acid, the 42S particles from early oocytes of Xenopus laevis and Tinca tinca incorporate radioactivity into tRNA and into a high molecular mass material which can be identified as protein. This incorporation is totally independent of ribosomes of cytosolic, mitochondrial or bacterial origin. The incorporated amino acids are linked to a broad spectrum of proteins by covalent bonds. Simple treatments such as incubation in buffer or addition of synthetic polyribonucleotides can inhibit the protein-labeling activity of the particles without affecting their tRNA aminoacylation activity. The former activity corresponds either to an amino acid polymerization reaction or to a protein-modifying reaction of a novel type. No involvement of mRNA in this process has been demonstrated. The alleged amino acid polymerization activity of the 42S particles could be a consequence of the conditions provided to aminoacyl tRNA by the tRNA-binding sites of the particles. These conditions are likely to allow the peptidyl transfer reaction to take place, although at a much lower rate than in the ribosome.

Biochemical research on oogenesis. Binding of tRNA to the nucleoprotein particles of Xenopus laevis previtellogenic oocytes

In previtellogenic oocytes of Xenopus laevis, nearly all tRNA is included in nucleoprotein particles (thesaurisomes) sedimenting at 42 S. We evaluate the possibility of a tRNA exchange between the particles and the ribosomes during protein synthesis. We find that the particles take up tRNA after a very short incubation in vitro. In the absence of ATP, the particles preferentially bind charged tRNA. In the presence of ATP, more tRNA binds to the particles, and the sedimentation coefficient of the integrated tRNA is displaced to 45 S. When added to nonfractionated homogenates of oocytes together with ATP, poly(U) strongly stimulates the incorporation of radioactive phenylalanine into tRNA and protein. The labeled protein (polyphenylalanine) cosediments with the ribosomes, whereas most of phenylalanyl tRNA cosediments with the thesaurisomes. These data suggest that the thesaurisomes participate to some extent in protein synthesis. They release charged tRNA, thereby supplying the ribosomes with activated amino acids. Discharged tRNA is then taken up, reacylated, and stored in the particles until the next round of peptide bond formation. The aminoacylation and storage functions are probably carried out by two very unequal populations of particles. The main subclass of particles (42 S) binds and stores tRNA in an ATP-independent manner. A much smaller subclass of particles (45 S) is responsible for reacylation of discharged tRNA.

Enzyme-linked immunosorbent assay for amitriptyline and other antidepressants using a monoclonal antibody

We describe and evaluate a method to measure amitriptyline and other tricyclic antidepressants by enzyme linked immunosorbent assay, using monoclonal antibody. In this assay, biological samples were first incubated with the antibody; in a second step, free remaining antibody was allowed to bind to lysozyme-nortriptyline coated immunotitration plates. The bound fraction of the monoclonal antibody was revealed with rabbit anti-mouse serum coupled to horseradish peroxidase. The optical density of the reaction product was measured with a colorimeter at 410 nm. Specificity of the antibody was investigated by means of a Farr test showing interferences in therapeutic ranges only for chlorpromazine and phenytoine. Means of intra- and inter-assay variations were 10 and 13%, respectively. The results when compared to those obtained by gas chromatography with a selective nitrogen detector gave a correlation coefficient of 0.897. Finally, the great reliability of the monoclonal antibody, the advantages of a decreased analysis time, low cost and high capacity of the procedure contribute to make this immunoassay most suitable for clinical monitoring and pharmacokinetic studies of tricyclic antidepressants.

Biochemical research on oogenesis. Aminoacyl tRNA turns over in the 42-S particles of Xenopus laevis oocytes, but its ester bond is protected against hydrolysis

The ester bond aminoacyl tRNA is protected against hydrolysis in the 42-S particles (thesaurisomes) present in Xenopus laevis previtellogenic oocytes. Deacylation of tRNA is very slow in vitro, unless ATP is present. ATP causes a partial turnover of aminoacyl tRNA in vitro, with no detectable decrease in the overall aminoacylation level of tRNA, which remains close to 100%. tRNA in the particles turns over rapidly in vivo. Since the ester bond of aminoacyl tRNA is stabilized inside the 42-S particles, this turnover cannot be a consequence of spontaneous deacylation of tRNA, followed by reacylation by the aminoacyl-tRNA synthetases associated with the particles. We rather consider this turnover as reflecting a true metabolic activity of the particles, and a direct or indirect involvement of these particles in the oocyte's protein-synthesizing system.

Biochemical Research on oogenesis. Composition of the 42-S storage particles of Xenopus laevix oocytes

Previtellogenic oocytes of Xenopus laevis contain far more 5-S RNA and tRNA than 28-S + 18-S RNA. tRNA and 5-S RNA are storage products that will be used in later oogenesis for protein synthesis and ribosome assembly. Stored tRNA and 5-S RNA are not free in the cell sap but belong to nucleoprotein particles of various sizes. There are two prominent kinds of storage particles in previtellogenic oocytes of X. laevis. The smaller ones (7-S) contain about half of the cell's 5-S RNA. The larger ones (42-S) contain the remainder of the 5-S RNA and 90% of the tRNA. The 7-S particles consist of one molecule of 5-S RNA and one molecule of protein. In this paper we describe the biochemical and physical properties of the 42-S particles. The 42-S particle contains four main components: tRNA, 5-S RNA, a 50000-Mr protein (a) and a 40000-Mr protein (b) in the following molar ratios: 3/1/2/1. We propose a 28-component model for the 42-S particles. This model is consistent with all the biochemical and physical data that we report here. A 42-S particle is made up of four subunits, each of which contains three molecules of tRNA, one molecule of 5-S RNA, two molecules of protein a, and one molecule of protein b. Protein b from the 42-S particles and the 7-S particle protein are indistinguishable by all tests that we have tried. We present evidence showing that protein a binds tRNA whereas protein b binds 5-S RNA in the 42-S particles as well as in the 7-S particles.