Immigration, emigration and the ageing of the overseas-born population in the United Kingdom

This article uses data from the 1971 and 2001 Censuses, the 1999-2003 Labour Force Survey and the 1977 to 2002 International Passenger Survey to investigate the migration processes contributing to the age structure and ageing of the UK's overseas-born population. Overall almost half of recent decades' immigrants to the UK emigrate again within five years of arrival, but with large variation by overseas country of birth. Between half and two thirds of the immigrants born in the continental European Union, North America and Oceania emigrate again within five years, while 15 per cent of those born in the Indian subcontinent do so. Significant cumulative emigration more than five years after arrival is seen among earlier immigrants from the Indian subcontinent, the Caribbean Commonwealth and Europe. Large country-of-origin variations in the ratio of pension-age population to working-age population primarily reflect the country composition of immigration streams 30 or more years before.     

Quantum Mechanics and Computation

In quantum computation non classical features such as superposition states and entanglement are used to solve problems in new ways, impossible on classical digital computers.We illustrate by Deutsch algorithm how a quantum computer can use superposition states to outperform any classical computer. We comment on the view of a quantum computer as a massive parallel computer and recall Amdahls law for a classical parallel computer. We argue that the view on quantum computation as a massive parallel computation disregards the presence of entanglement in a general quantum computation and the non classical way in which parallel results are combined to obtain the final output.     

Algebraic Self-Dualityc as the ”Ultimate Explanation”

Shahn Majids philosophy of physics is critically presented. In his view the postulate that the universe should be self-explaining implies that no fundamental theory of physics is complete unless it is self-dual. Majid shows that bicrossproduct Hopf algebras have this property. His philosophy is compared with other approaches to the ultimate explanation and briefly analyzed.     

Isolation of human epidermal stem cells by adherence and the reconstruction of skin equivalents

The isolation of human epidermal stem cells is critical for their clinical applications. In the present study, we isolated three populations of epidermal keratinocytes according to their ability to adhere to collagen type IV: i.e., rapidly adhering (RA), slowly adhering (SA), and non-adhering (NA) cells. The aim of this study was to characterize RA cells and to investigate the possibility of using these cells for epidermis reconstruction. To identify RA cells, flow cytometric analysis was performed using anti-₆ integrin and anti-CD71 antibodies. RA cells express high levels of ₆ integrin and low levels of CD71, which are considered as markers of an epidermal stem cell nature. Furthermore, electron microscopy showed that RA cells are small and have a high nuclear to cytoplasmic ratio, whereas SA and NA cells have well-developed cellular organelles and abundant tonofilaments. Western blot analysis showed that RA cells are slow cycling and express p63, a putative epidermal stem cell marker, whereas SA and NA cells express c-Myc, which is known to regulate stem cell fate. To compare epidermal regenerative abilities, skin equivalents (SEs) were made using RA, SA, and NA cells. The epidermis constructed from RA cells was well formed compared to those formed from SA or NA cells. In addition, only SEs with RA cells expressed ₆ integrin and ₁ integrin at the basal layer. These results indicate that RA cells represent epidermal stem cells and are predominately comprised of stem cells. Therefore, the isolation of RA cells using a simple technique offers a potential route to their clinical application, because they are easily isolated and provide a high yield of epidermal stem cells.Received 2 July 2004; received after revision 20 August 2004; accepted 10 September 2004     

Involvement of penaeidins in defense reactions of the shrimp Litopenaeus stylirostris to a pathogenic vibrio

The present study reports for the first time the involvement of an antimicrobial peptide in the defense reactions of a shrimp infected by a pathogenic Vibrio, Vibrio penaeicida. New members of the penaeidin family were characterized in the shrimp Litopenaeus stylirostris by RT-PCR and RACE-PCR from hemocyte total RNAs, and by mass spectrometry detection and immunolocalization of mature peptides in shrimp hemocytes. In infected shrimps, bacteria and penaeidin distribution colocalized in the gills and the lymphoid organ that represented the main infected sites. Moreover, the shrimp immune response to infection involved massive hemocyte recruitment to infection sites where released penaeidin may participate in the isolation and elimination of the bacteria, We show that the ability of the shrimps to circumvent shrimp infections is closely related to a recovery phase based on the hematopoietic process.Received 25 November 2003; received after revision 8 January 2004; accepted 21 January 2004     

Functional investigations of exercising muscle: a noninvasive magnetic resonance spectroscopy-magnetic resonance imaging approach

Muscle fatigue, which is defined as the decline in muscle performance during exercise, may occur at different sites along the pathway from the central nervous system through to the intramuscular contractile machinery. Historically, both impairment of neuromuscular transmission and peripheral alterations within the muscle have been proposed as causative factors of fatigue development. However, according to more recent studies, muscle energetics play a key role in this process. Intramyoplasmic accumulation of inorganic phosphate (P_i) and limitation in ATP availability have been frequently evoked as the main mechanisms leading to fatigue. Although attractive, these hypotheses have been elaborated on the basis of experimental results obtained in vitro, and their physiological relevance has never been clearly demonstrated in vivo. In that context, noninvasive methods such as 31-phosphorus magnetic resonance spectroscopy and surface electromyography have been employed to understand both metabolic and electrical aspects of muscle fatigue under physiological conditions. Mapping of muscles activated during exercise is another interesting issue which can be addressed using magnetic resonance imaging (MRI). Exercise-induced T2 changes have been used in order to locate activated muscles and also as a quantitative index of exercise intensity. The main results related to both issues, i.e. the metabolic and electrical aspects of fatigue and the MRI functional investigation of exercising muscle, are discussed in the present review.Received 4 September 2003; received after revision 4 December 2003; accepted 22 December 2003     

Ubiquitin-proteasome pathway as a primary defender against TRAIL-mediated cell death

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptotic cell death as well as expression of proinflammatory genes such as CXCL8 in malignant human astrocytoma cells. However, the molecular mechanisms that determine the fate of cells are not yet understood. The ubiquitin (Ub)-proteasome pathway regulates a wide range of cellular functions through degradation of various regulatory proteins; given this, we hypothesized that this pathway may play a central role in TRAIL-mediated signaling. We demonstrate here that inhibition of the Ub-proteasome pathway enhanced TRAIL-mediated cell death of human astrocytoma CRT-MG cells within hours by blocking degradation of active caspase-8 and -3. Proteasome inhibitors suppressed TRAIL-mediated activation of NF-B; however, inhibition of the NF-B pathway alone was not sufficient to enhance TRAIL-mediated cell death. Collectively, these results suggest that the Ub-proteasome pathway may play an important role as an antiapoptotic surveillance system by eliminating activated caspases as well as mediating NF-B-dependent signals.Received 30 December 2003; received after revision 9 February 2004; accepted 13 February 2004     

Alexander disease: putative mechanisms of an astrocytic encephalopathy

Alexander disease (AXD) is the first primary astrocytic disorder. This encephalopathy is caused by dominant mutations in the glial fibrillary acidic protein (GFAP) gene, encoding the main intermediate filament of astrocyte. Pathologically, this neurodegenerative disease is characterised by dystrophic astrocytes containing intermediate filament aggregates associated with myelin abnormalities.More than 20 GFAP mutations have been reported. Many of them cluster in highly conserved regions between several intermediate filaments. Contrary to other intermediate filament-related diseases, AXD seems to be the consequence of a toxic gain of function induced by aggregates. This is supported by the phenotype of mice overexpressing human GFAP. Nevertheless, GFAP null mice display myelin abnormalities and blood-brain barrier dysfunction that are present in AXD.Given the pivotal role of astrocytes in brain physiology, there are many possibilities for astrocytes to dysfunction and to impair the functions of other cells. Physiopathological hypotheses are discussed in the frame of AXD.Received 11 April 2003; received after revision 22 July 2003; accepted 31 July 2003Both authors contributed equally to this work.