Le syndrome de Diogène, une approche transnosographique

Diogenes syndrome is a behavioural disorder of the elderly. Symptoms include living in extreme squalor, a neglected physical state and unhygienic conditions. This is accompanied by a self-imposed isolation, the refusal of external help and a tendency to accumulate heteroclite objects. This particular geriatric syndrome has been described for the first time only quite recently, as the 2 primary descriptions by geriatricians and psychiatrists date from 1966 and 1975 respectively. Its rare occurrence contrasts with the fact that it is well-known, partly due to it being named after the Greek philosopher "Diogene de Sinope", who taught cynicism philosophy and a return to a natural way of life, and partly because of its rare characteristics. The Diogenes syndrome is a fascinating object of study for the clinician who takes care of patients living in uncommon conditions, on the edge of society and unaware of the particularity of their lifestyles. Patients suffering from Diogenes syndrome are usually discovered by chance, either because of a somatic illness, or as a result of social intervention related to their behavioural problems. Management of the syndrome is difficult and ethically challenging, as the patient does not seek help. Moreover, 46% of patients have a 5 year mortality rate. Hospitalisation has to be avoided whenever possible and ambulatory treatment and social measures should be favoured. Psychotropic treatment prescription may be necessary, depending on clinical features and the possible underlying psychiatric disease. Although several clinical hypotheses have been suggested, the true ethiopathogeny of the syndrome remains unclear. Most authors agree that this behaviour does not reflect free will and has consequently no theoretical relationship to the Greek philosopher. There is no true consensus about diagnostic criteria. They include the main features of the syndrome and exclude known psychiatric syndromes. Clark and Mankikar, who named this syndrome, reckon it may represent stress-related defence mechanisms of the elderly or may be related to natural ageing process. However, psychiatric pathologies as paranoid and paranoiac psychoses, mood disorders and obsessive and compulsive disorders have been described to be associated with it in the literature. Dementia, in particular temporo-frontal dementia, should be looked for and excluded clinically. Alcohol abuse seems to be an aggravating rather than a precipitating factor. Finally, the link between these pathologies and Diogenes syndrome is not yet determined: are they triggering, co-morbid or etiological factors? Should this syndrome be considered as a true illness or as a symptom? This paper presents Diogenes syndrome as a behavioural disorder and distinguishes 2 types: the "active type"--patients who collect from outside to clutter inside--and the "passive type"--patients who passively become invaded by their rubbish. Active type patients fill their home to fill in the vacuum of their life, as it deteriorates and looses its narcissical appeal. Passive type patients accumulate by default and emptiness. A psychopathological understanding is presented here, referring to psychoanalytical theories of the Moi-peau (ego-skin) described by Anzieu. The Moi-peau represents a structure of the psyche founded on the following principle: any psychic function develops itself according to a bodily function from which it transposes its functioning at a mental level. The skin has three functions: the containing shell, the protective barrier of the psyche, and a medium of exchange. The Moi-peau is organised as a double-wall acting both as a defence mechanism and as a filter between the psyche and the external world. It preserves the relationship and the cohesion "container-content". As a result of a narcissical wound, the Moi-peau is damaged and looses its function of a container. In the case of Diogenes Syndrome, the accumulated items repair the Moi-peau and the home becomes an "exterior-proof", thus playing the role of the Moi-peau. This behaviour therefore plays a repairing role for psychic functioning, allowing psychic survival.

Rapid turnover of extracellular signal-regulated kinase 3 by the ubiquitin-proteasome pathway defines a novel paradigm of mitogen-activated protein kinase regulation during cellular differentiation

Mitogen-activated protein (MAP) kinases are stable enzymes that are mainly regulated by phosphorylation and subcellular targeting. Here we report that extracellular signal-regulated kinase 3 (ERK3), unlike other MAP kinases, is an unstable protein that is constitutively degraded in proliferating cells with a half-life of 30 min. The proteolysis of ERK3 is executed by the proteasome and requires ubiquitination of the protein. Contrary to other protein kinases, the catalytic activity of ERK3 is not responsible for its short half-life. Instead, analysis of ERK1/ERK3 chimeras revealed the presence of two destabilization regions (NDR1 and -2) in the N-terminal lobe of the ERK3 kinase domain that are both necessary and sufficient to target ERK3 and heterologous proteins for proteasomal degradation. To assess the physiological relevance of the rapid turnover of ERK3, we monitored the expression of the kinase in different cellular models of differentiation. We observed that ERK3 markedly accumulates during differentiation of PC12 and C2C12 cells into the neuronal and muscle lineage, respectively. The accumulation of ERK3 during myogenic differentiation is associated with the time-dependent stabilization of the protein. Terminal skeletal muscle differentiation is accompanied by cell cycle withdrawal. Interestingly, we found that expression of stabilized forms of ERK3 causes G(1) arrest in NIH 3T3 cells. We propose that ERK3 biological activity is regulated by its cellular abundance through the control of protein stability.

Delayed gametogenesis and progesterone levels in soft-shell clams (Mya arenaria) in relation to in situ contamination to organotins and heavy metals in the St. Lawrence River (Canada)

There is a growing awareness that contaminants in the aquatic environment may alter steroid hormone levels and affect the reproductive success of the invertebrates. To verify if heavy metals and organotins affect sexual maturation in Mya arenaria, individuals were collected from July to November 1998, at different sites along the South coast of the St. Lawrence maritime estuary. Near the Rimouski harbour, clams showed high levels of tributyltin (TBT), DBT in the gonad, along with a lower gonado-somatic index [GSI=gonad wet weight (g)/body wet weight without shell (g)x100], low progesterone levels and a delay in sexual maturation when compared to the reference site. Sites that had intermediate levels of contaminants exhibited intermediate responses of hormones and sexual maturation stages. It is therefore suggested that TBT, DBT are endocrine disruptors in clams. Further studies will however be necessary to investigate in more details how contaminants as TBT can affect the steroid hormones production in the gonads of M. arenaria.

Sex alteration in soft-shell clams (Mya arenaria) in an intertidal zone of the Saint Lawrence river (Quebec, Canada)

The purpose of this study was to verify whether any changes in sex ratio might occur in soft-shell clams (Mya arenaria) located in an intertidal harbor zone located at the mouth of the Saguenay Fjord in the Saint Lawrence estuary (Baie Sainte-Catherine (BSC), Québec, Canada) likely to be contaminated by organotin compounds. Bivalves were harvested at the BSC harbor site and from two reference sites. Condition index (weight to length ratio), gonado-somatic index, sex ratio, vitellin-like proteins, organotin concentrations in gonad tissue, maturation stages of the gonads, the number of estradiol-17beta binding sites and the capacity of female gonad extracts to produce estradiol-17beta were determined in collected animals. Results showed that sex ratio in clams was significantly skewed toward males. Moreover, the condition and gonad-somatic indices, vitellin-like proteins in female gonads and the capacity of female gonads to produce estradiol-17beta were significantly reduced at the harbor site with respect to the reference sites. Maturation status of male gonads was clearly delayed at the harbor site. Additionally, gonad tissue contained tributyltin (TBT) at an average level of 109+/-18 ngSn/gdry wt. at the harbor site while organotins were not detected from the reference sites. Finally, female gonads had a higher number of unoccupied estradiol binding sites at the harbor site indicating low levels of this steroid in this tissue. Overall, this paper is first to report that clams collected in the vicinity of a TBT contaminated harbor are subject to masculinizing effects which seems to be consistent with biological effects that organotins are known to exert toward some other marine invertebrates.

Health assessment of a marine bivalve Ruditapes decussatus from the Gulf of Gabès (Tunisia)

Metallothioneins (MTs), malonedialdehyde (MDA), and glycogen concentrations were determined in order to assess the health status of Ruditapes decussatus exposed to in situ contamination, showing the effects of time, site, and metal contamination on these three biomarkers. Metallothionein was positively correlated with Cd and Zn. If introduced in a multiple model, the factors site and time were shown to decrease significantly MT concentrations. MDA was inversely correlated with size of the animals and was affected by the factor time. Glycogen was inversely correlated with zinc and was affected by both site and time.This study constitutes a field-based validation of a multiparametric approach using specific and nonspecific biomarkers.

Effects of exposure of Mya arenaria and Mactromeris polynyma to contaminated marine sediments on phagocytic activity of hemocytes

Two species of bivalves, Mya arenaria and Mactromeris polynima, were exposed to contaminated marine sediments from Baie des Anglais, Quebec, for a period of 10 and 12 weeks, respectively, in order to determine if there was an effect on the phagocytic activity of hemocytes from each species. These sediments contain elevated levels of both PAHs and PCBs. Uncontaminated beach sand was used as control sediments. After a period of 4 weeks, each species of bivalves were sampled and hemocyte phagocytic activity was monitored by flow cytometry. While phagocytosis by hemocytes from M. polytiyma was significantly suppressed, those from M. arenaria were not different from beach sand-exposed controls. At the end of the exposure period, the phagocytic activity of hemocytes from both species was suppressed. Physiological parameters such as mantle proteins or malondialdehyde levels, total protein and total glycogen levels in the digestive gland were not affected by exposure to contaminated sediments. Moreover, the suppression of phagocytosis was well correlated with the transfer of contaminants from the sediments to the bivalves and their subsequent bioaccumulation, as demonstrated by the PCB body burden. These results support the use of bivalves as good sentinel species to survey sediment contamination and the usefulness of hemocyte phagocytic activity as a sensitive biomarker of exposure to organic contaminants.

Phagocytic activity of marine and freshwater bivalves: in vitro exposure of hemocytes to metals (Ag, Cd, Hg and Zn)

We measured non-specific immune function of various bivalves from marine (Cyrtodaria siliqua, Mactromeris polynyma, Mesosdesma arctatum, Mya arenaria, Mya truncata, Mytilus edulis, Serripes groenlandicus, Siliqua costata) and freshwater environments (Dreissena polymorpha and Elliptio complanata). We used flow cytometry to quantify the phagocytosis of fluorescent microspheres by hemocytes exposed in vitro to increasing levels of various metal compounds (AgNO(3), CdCl(2), CH(3)HgCl, HgCl(2) and ZnCl(2)). In some species, low doses of mercury (organic and inorganic) and Zn suggest a hormesis-like stimulation of phagocytic activity. At higher levels of exposure, all metals tested induced a significant dose-related inhibition of hemocyte phagocytosis. The species-specific sensitivity of the assay was determined by comparing the in vitro exposure using the metal concentration inducing a 50% suppression (EC(50)) of the phagocytic activity. Different species expressed different levels of sensitivity. Our results show the variability of the toxic response of different species within a group of similar organisms. It also highlights the need to consider species-species differences in ecotoxicological risk assessment.

Seasonal gonad progesterone pattern in the soft-shell clam Mya arenaria

Steroidogenesis, which plays a major role in the reproductive cycle of vertebrates, is still for the most part, unknown in invertebrates. The aim of this study was to examine the link between progesterone and the reproductive cycle in Mya arenaria. The soft-shell clams, Mya arenaria were collected in Anse à l'Orignal (Parc Provincial du Bic, Québec, Canada) from July to November 1998. Histological data have shown that female gonads of M. arenaria were in the spawning stage in August and September, while the male gonads were in the ripe stage. This period of active gametogenesis was associated with a depletion of lipid reserves. These lipids could be used as a source of energy and as a substrate for steroidogenesis. Liquid Chromatography coupled to Mass Spectroscopy (LC-MS) and quantified by Enzyme Linked ImmunoSorbent Assay (ELISA) determined progesterone. Progesterone levels in the gonad were increased during the ripe stage in the male and during the spawning stage in the female. These results indicate, for the first time, that progesterone, as in vertebrates, may play a role in the reproductive cycle of M. arenaria.

Delayed gametogenesis of Mya arenaria in the Saguenay fjord (Canada): a consequence of endocrine disruptors?

The Saguenay fjord located in Canada on the north coast of the Saint-Lawrence Estuary, is well known for its multiple contaminations following a linear distribution upstream to downstream. Mya arenaria is well established in the fjord and potentially exposed to persistent sediment contamination as an endobenthic bivalve. From May to October 1997, clams energy storage and utilization in the gonad was shown to be closely linked with reproduction. Wherever the sampling site location in the fjord, a seasonal pattern is evident for lipid and glycogen levels in the gonad, this, reflecting the vitellogenic process. Nevertheless, in comparison with energy status and gametogenesis of clams collected on the north coast of the Saint-Lawrence Estuary, clams located in the fjord have to face limited nutritive conditions resulting in a single and shorter reproductive period. Although environmental factors could explain differences in physiological condition and reproductive status observed between clams from the fjord and the estuary, our results can discriminate clams from the upper part of the fjord, according to a delayed gametogenesis, concomitant with significant higher gonad glycogen concentrations observed in June 1996 and 1997. A persistent dysfunction of a vitellogenic process is suspected to be due to the exposure to anti-estrogenic contaminants.

Alteration of the biochemical properties of female gonads and vitellins in the clam Mya arenaria at contaminated sites in the Saguenay Fjord

Vitellins (Vn) are the major egg yolk proteins that constitute an important energy reserve for mollusc embryos. The purpose of the present study was to examine whether the relative levels of sugars, lipids, phosphates, and labile IIb metals and calcium normally associated with Vn would differ in clam populations living at contaminated sites. Softshell clams (Mya arenaria) were collected at three sites in the area of the Saguenay Fjord: a marina, a municipal sewer outfall zone, and a reference site. The condition factor (weight:length ratio), metallothionein-like proteins, cytochrome P450 1A1 activity and DNA damage were all determined in the clam's digestive gland. Levels of total sugars, lipids, alkali-labile phosphates, proteins, and labile zinc and calcium were determined in female gonad homogenates and in purified Vn. The results show that clam gonads at the contaminated site by a marina displayed a lower index of gonad activity than the reference site. In addition, the condition factor was significantly lower at the marina site as compared to the reference site, with a concomitant increase in DNA damage and metallothionein (MT) induction. In fact, the condition factor was significantly correlated with DNA damage (R = -0.413, P = 0.045) and MT levels (R = -0.622, P = 0.03). Homogenates of female gonads were found to contain higher levels of labile IIb metals and calcium, with lower lipid content at the marina site compared to the reference site, and much higher levels of alkali-labile phosphates (ALP) and calcium at the municipal outfall site. Vn from the marina site were significantly higher in labile IIb metals but lipid content appeared to be somewhat lower than at the reference site. Vn from the municipal site were found to be highly phosphorylated, with higher levels of lipids and calcium. These results suggest that the chemical composition of the gonads and Vn are altered in contaminated sites.

Molluscan shellfish biomarker study of the Quebec, Canada, Saguenay Fjord with the soft-shell clam, Mya arenaria

A spatial and temporal survey of six sites in the Saguenay Fjord and of one adjacent site in the St. Lawrence River estuary (Quebec, Canada) was undertaken to study the possible effects of anthropogenic contaminant input on soft-shell clam (Mya arenaria) populations. Bivalve sampling sites were selected because they reflected a range of areas representative of either no known (or apparent) pollution sources or of areas potentially influenced by different gradients and types of contamination sources. The most upstream site selected in the Saguenay Fjord, nearest to a highly populated and industrialized sector, and the most downstream site, near its mouth with the St. Lawrence River estuary, spanned a distance of some 70 km and encompassed the entire intertidal area suitable for Mya arenaria habitat. To measure effects in collected animals, we used a comprehensive battery of biomarkers composed of metallothionein-like proteins (MT), 7-ethoxyresorufin O-deethylase activity (EROD), DNA damage (DD), lipid peroxidation (LPO), vitellinlike proteins (Vn), phagocytosis (PHAG), nonspecific esterase (NspE) activity, and condition factor (weight-to-length ratio of clams). Vn, PHAG, DD, and NspE biomarkers were assayed in hemolymph (or hemocytes), whereas others (MT, EROD, LPO) were determined in the digestive gland. Whole-tissue metal content was also quantified in clams collected in the spatial survey. The spatial survey conducted in June 1997 showed significant effects at all sites, and principal component analysis indicated in addition that the more important responses were linked to the MT, LPO, and NspE biomarkers. Clams collected from sites closest to the upstream reaches of the fjord generally displayed higher levels of tissue metals (cadmium, manganese), as well as greater responses of NspE activity, MT, LPO, and PHAG. Animals collected from sites influenced by municipal wastewaters had higher levels of Vn, suggesting the presence of environmental estrogens. The results of the temporal survey (six monthly samplings of clams at three sites from May through October, 1997) showed that the bivalve reproductive cycle (vitellogenesis and spawning) can modulate the expression of several biomarkers. Vn levels, for example, were positively correlated with DD and EROD and negatively correlated with MT, suggesting that reproduction can influence the susceptibility of clams to some contaminants. Discrimination analysis over the 6 months of sampling revealed that the mean value of the discriminant function changed significantly over time, suggesting important changes in the relative contribution of each biomarker. In short, this study has provided evidence that clam populations in the Saguenay Fjord are impacted by multiple sources of contamination whose effects can be modulated by reproduction.

[Neuropsychic effects of dehydroepiandrosterone]

Dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S) are secreted primarily by the adrenal glands. DHEA could also be a neuroactive steroidal hormone. Because basal levels of DHEA and DHEA-S in humans decrease significantly with age, these hormones have been assumed to be involved in the aging process and in a number of pathologies which develop with aging: immunosenescence, increased mortality, increased incidence of cancer, osteoporosis and cardiovascular diseases. However, its role is still unknown. In humans, cross sectional and longitudinal studies have shown that DHEA might be associated with global measures of well-being and functioning, but positive effects on measures of memory and attention could not be found. Studies investigating DHEA and DHEA-S levels in dementia have produced controversial results. Short-term experimental studies have not shown significant improvement in global measures of well-being and functioning in healthy subjects but have revealed preliminary evidence for mood enhancing and antidepressant effects of DHEA. There is no evidence that DHEA could induce addiction in human beings.

Effects of in vivo exposure of Mya arenaria to organic and inorganic mercury on phagocytic activity of hemocytes

Marine bivalves are aquatic invertebrate organisms which can be used as bioindicators in environmental monitoring. In vivo effects of mercuric chloride (HgCl(2)) and methylmercury (CH(3)HgCl) on phagocytic function of Mya arenaria hemocytes were evaluated in this study. Clams were exposed to single metal in water for up to 28 days at concentrations ranging from 10(-9) to 10(-5) M. Phagocytic activity of hemocytes was determined by uptake of fluorescent microspheres and flow cytometry. All clams exposed to 10(-5) M HgCl(2) died by day 7 of exposure. The viability of hemocytes was decreased only in clams exposed to 10(-6) M HgCl(2) for 28 days. A significant decrease in phagocytic activity of hemocytes was observed in clams exposed to 10(-6) M of HgCl(2) for 28 days. A similar pattern was observed with CH(3)HgCl, but at an earlier time. Chemical analysis performed on the tissues of the animals clearly show a greater uptake of the organic form of mercury by clams. Furthermore, a clear correlation was established between body burden of mercury and effects on phagocytic activity of hemocytes. Overall, the results of this study show that both speciations of mercury inhibited phagocytic function of Mya arenaria hemocytes following in vivo exposures.

The potential use of metallothionein in the clam Ruditapes decussatus as a biomarker of in situ metal exposure

This work aimed to validate the relationship between metallothioneins (MTs) and metals (Cd, Cu and Zn) in field conditions. Specimens of the marine bivalve Ruditapes decussatus (Linné, 1758) from Gargour were transferred in two sites: Gargour and Sidi Mansour, both situated along the south-eastern coast of Tunisia. The bivalves were removed from pairs of cages at day 0 (date of transplantation), day 62 and day 132. Metals (Cd, Cu and Zn) and MTs were determined in the subcellular fractions of the digestive gland. In Gargour, metal and MT levels increased significantly after 62 days of transplantation. However, they showed modest and non-significant variations in Sidi Mansour. Zn was mainly associated with the insoluble fraction, whereas Cd and Cu percentages in the soluble and the insoluble fractions were equivalent. Simple correlation analysis showed a positive and significant relationship between MTs and each metal. If all metals were taken together, multiple correlations showed that MTs were significantly correlated with Cd and Zn, with an important coefficient for Cd, but no significant relationship was observed for Cu. Gel filtration chromatography showed that in the heat stable fraction, the only cytosolic SH rich compounds have an apparent low molecular mass (about 15 kDa), which could correspond to metallothioneins. In the digestive gland of R. decussatus MTs responded to moderate increases of metal contamination, without interference with other factors, and could be a promising biochemical indicator of metal exposure.

Chromosome mapping of the human genes encoding the MAP kinase kinase MEK1 (MAP2K1) to 15q21 and MEK2 (MAP2K2) to 7q32

Activation of the ERK mitogen-activated protein (MAP) kinase pathway has been implicated in the regulation of cell growth, differentiation and senescence. In this pathway, the MAP kinases ERK1/ERK2 are phosphorylated and activated by the dual-specificity kinases MEK1 and MEK2, which in turn are activated by serine phosphorylation by a number of MAP kinase kinase kinases. We report here the chromosomal localization of the human genes encoding the MAP kinase kinase isoforms MEK1 and MEK2. Using a combination of fluorescence in situ hybridization, somatic cell hybrid analysis, DNA sequencing and yeast artificial chromosome (YAC) clone analysis, we have mapped the MEK1 gene (MAP2K1) to chromosome 15q21. We also present evidence for the presence of a MEK1 pseudogene on chromosome 8p21. The MEK2 gene (MAP2K2) was mapped to chromosome 7q32 by fluorescence in situ hybridization and YAC clone analysis.

[Mental anorexia in aging. Report of a case]

Elderly subjects who refuse to eat, and thus develop malnutrition, can be observed both in institutional and community settings. Causes include physiological changes related to the aging process, mental disorders and environmental factors. Most cases of anorexia nevrosa begin in adolescence but a sizeable number may develop at a later age. The term anorexia nevrosa in the elderly is proposed to describe this clinical entity observed in a woman who developed anorexia nevrosa at the age of 76 years. This entity is examined in comparison with prolonged earlier-onset anorexia nevrosa and late-onset anorexia.

Assessment of dementia in elderly outpatients: a comparative study of European centers and consensus statement

Large numbers of elderly patients, suspected of having dementia, need medical evaluation, often in early phases of their illness. A complete outpatient assessment clearly could be advantageous. Thirty-five centers from 15 European countries, known to their scientific gerontological and geriatric societies to have experience in outpatient care for elderly patients with dementia, participated in an effort to develop a consensus statement for the assessment needs of these patients. The comparison of the centers showed that a wide variety of approaches was currently in practice. Differences appeared to be mainly based on local facilities and organization. A consensus for diagnostic outpatient assessment was easily reached. Diagnosis should be based on DSM-IV criteria, which requires a standardized assessment (including neuropsychological, functional and technical evaluation) and should be multidisciplinary. An assessment of dementia of elderly outpatients appears to be very feasible - a consensus approach with minimum diagnostic requirements is presented.

Flow cytometry as a tool to monitor the disturbance of phagocytosis in the clam Mya arenaria hemocytes following in vitro exposure to heavy metals

The effectiveness of toxicology biomonitoring programs could be improved by the addition of sensitive biomarkers. In this study the cell viability and sensitivity of phagocytic function of phagocytes from bivalves (Mya arenaria) to selected heavy metals were measured by flow cytometry, a novel approach. Hemocytes (phagocytes) collected from bivalves by puncture of the posterior adductor muscle were incubated in vitro for 18 h in hemolymph containing 10(-9)-10(-3)M of cadmium chloride, zinc chloride, mercuric chloride, methylmercury chloride or silver nitrate, before determining their capacity to phagocytose fluorescent latex beads by flow cytometry. Heterogeneity of the hemocyte cell population was determined by forward scatter (FSC) and side scatter (SSC) cytometric profile which showed two distinct cell populations. At low doses (10(-9), 10(-8) M), all the metal compounds studied stimulated phagocytic activity except silver nitrate. At higher levels of exposure (10(-6), 10(7) M), all metals caused a significant concentration-related decrease in hemocyte phagocytosis activity. From the concentration of each metal inducing 50% suppression (IC50) of the phagocytic activity, the immunotoxic potential of metals with respect to phagocytic function can be ranked in the following increasing order: ZnCl2 < CdCl2 < AgNO3 < HgCl2 < CH3HgCl. Parallel analysis of hemocyte viability showed that suppression of phagocytosis by heavy metals was not solely related to a decreased cell viability. These results reveal the high but different degree of sensitivity of the phagocytosis activity of bivalves with respect to heavy metals, as measured by flow cytometry, and demonstrate that flow cytometry is a potentially useful tool in ecotoxicological monitoring.

Primary structure, expression and chromosomal locus of a human homolog of rat ERK3

We report the cloning and characterization of a human cDNA encoding a novel homolog of rat extracellular signal-regulated kinase 3 (ERK3). The cDNA encodes a predicted protein of 721 amino acids which shares 92% amino acid identity with rat ERK3 over their shared length. Interestingly, the human protein contains a unique extension of 178 amino acids at its carboxy terminal extremity. The human ERK3 protein also displays various degrees of homology to other members of the MAP kinases family, but does not contain the typical TXY regulatory motif between subdomains VII and VIII. Northern blot analysis revealed that ERK3 mRNA is widely distributed in human tissues, with the highest expression detected in skeletal muscle. The human ERK3 gene was mapped by fluorescence in situ hybridization to chromosome 15q21, a region associated with chromosomal abnormalities in acute nonlymphoblastic leukemias. This information should prove valuable in designing studies to define the cellular function of the ERK3 protein kinase.

[Growth hormone in adults. An elixir of youth?]

Studies have revealed a partial deficiency of growth hormone (GH) secretion in the elderly. Aging has a central effect on the GH secretion and probably a peripheral effect on insulin-like growth factor 1 (IGF-1) or somatomedin C through changes in body composition. Simultaneously therapeutic efficiency of recombinant GH was confirmed in adults with GH deficiency. These notions have led to some controlled trials of GH treatment in elderly. Further studies of GH replacement are needed, examining issues such as dosage, tolerance (still inadequate) and efficacy before the widespread use of GH or IGH-F 1 in the elderly is advocated.