Family building intentions in England and Wales: trends,outcomes and interpretations

This article presents and analyses women's childbearing intentions collected in the General Household Survey (GHS). Data from the 21 surveys from 1979 to 2001 show that over that period there has been a fall in women's intended numbers of births. However the latest data (from the 1998, 2000 and 2001 surveys) show that the average number of children intended is still around two, somewhat higher than the average number of children current fertility rates suggest women will have. The questions of whether this difference can be interpreted as possible unmet need for children, whether past intentions have been good predictors of fertility, and how current intentions may be used to inform projections assumptions are discussed. In relation to the last question, fertility intentions by ethnic group are also presented.     

Role of Cys221 and Asn116 in the zinc-binding sites of the Aeromonas hydrophila metallo-β-lactamase

The CphA metallo--lactamase produced by Aeromonas hydrophila exhibits two zinc-binding sites. Maximum activity is obtained upon binding of one zinc ion, whereas binding of the second zinc ion results in a drastic decrease in the hydrolytic activity. In this study, we analyzed the role of Asn116 and Cys221, two residues of the active site. These residues were replaced by site-directed mutagenesis and the different mutants were characterized. The C221S and C221A mutants were seriously impaired in their ability to bind the first, catalytic zinc ion and were nearly completely inactive, indicating a major role for Cys221 in the binding of the catalytic metal ion. By contrast, the binding of the second zinc ion was only slightly affected, at least for the C221S mutant. Mutation of Asn116 did not lead to a drastic decrease in the hydrolytic activity, indicating that this residue does not play a key role in the catalytic mechanism. However, the substitution of Asn116 by a Cys or His residue resulted in an approximately fivefold increase in the affinity for the second, inhibitory zinc ion. Together, these data suggested that the first zinc ion is located in the binding site involving the Cys221 and that the second zinc ion binds in the binding site involving Asn116 and, presumably, His118 and His196.Received 3 March 2003; received after revision 4 August 2003; accepted 25 August 2003     

How sphingolipids bind and shape proteins: molecular basis of lipid-protein interactions in lipid shells,rafts and related biomembrane domains

Understanding the molecular mechanisms controlling the association of proteins with lipid rafts is a central issue in cell biology and medicine. A structurally conserved motif (the 'sphingolipid binding domain') has been characterized in unrelated cellular and microbial proteins targeted to lipid rafts. I propose that the structuration of a sphingolipid shell around the sphingolipid binding domain not only extracts the protein from the liquid-disordered phase of the plasma membrane, and ensures its delivery to lipid rafts, but also influences its conformation. The chaperone activity of sphingolipids in shells and rafts may play an important role in infectious and conformational diseases(human immunodeficiency virus-1, prions, Alzheimer).     

Myocardial function and energy metabolism in carnitine-deficient rats

Carnitine is essential for mitochondrial metabolism of long-chain fatty acids and thus for myocardial energy production. Accordingly, carnitine deficiency can be associated with cardiomyopathy. To better understand this disease, we determined myocardial function and energy metabolism in a rat model of carnitine deficiency. Carnitine deficiency was induced by a 3- or 6-week diet containing N-trimethyl-hydrazine-3-propionate, reducing cardiac and plasma carnitine by 70-85%. Myocardial function was investigated in isolated isovolumic heart preparations. Carnitine-deficient hearts showed left ventricular systolic dysfunction, reduced contractile reserve, and a blunted frequency-force relationship independently of the substrate used (glucose or palmitate). After glycogen depletion, palmitate could not sustain myocardial function. Histology and activities of carnitine palmitoyl transferase, citrate synthase, and cytochrome c oxidase were unaltered. Thus, as little as 3-6 weeks of systemic carnitine deficiency can lead to abnormalities in myocardial function. These abnormalities are masked by endogenous glycogen and are not accompanied by structural alterations of the myocardium or by altered activities of important mitochondrial enzymes.     

Changes in calpastatin localization and expression during calpain activation: a new mechanism for the regulation of intracellular Ca<Superscript>2+</Superscript>-dependent proteolysis

The amount of calpastatin directly available in cytosol is under the control of [Ca²⁺] and [cyclic AMP]. Prolonged calpain activation also promotes degradation of calpastatin. The fluctuation of calpastatin concentration in cell soluble fraction is accompanied by an initial decrease in calpastatin gene expression, followed by a fivefold increase in its expression when the inhibitor protein is degraded. This process can be conceptualized as a mechanism to regulate calpastatin availability in the cell. This conclusion is supported by the fact that calpain, the other component of this proteolytic system, undergoes changes in its levels of expression in a much more limited manner. Furthermore, this process can be observed both in cells exposed to different natural stimuli, or in other cell lines. Modification of calpastatin gene expression might represent a new tool for the in vivo control of the regulatory machinery required for the modulation of Ca²⁺-dependent proteolysis.Received 18 July 2003; received after revision 3 September 2003; accepted 23 September 2003     

Structure and function of RGD peptides involved in bone biology

This review focuses on recent papers that describe the involvement of the RGD sequence in bone biology and incorporate the use of synthetic RGD peptides to develop new drugs or control the bioactivity of materials used for bone regeneration. Because in vivo bone function is completely dependent on angiogenesis and vessels, the present publication is focused on physiology, pathophysiology and therapeutics of RGD peptides dedicated to bone cells and endothelial systems. It appears that alphavbeta3, alphavbeta5 and alphaIIbbeta3 are the integrins most reported to be involved in bone function and RGD sequence binding. The specificity of RGD peptides depends on backbone conformation, orientations of the charged side chains of Arg and Asp residues, and hydrophobic moieties flanking the Asp residue. Despite of recent progress in integrins and RGD peptide structures and function, future work should focus on integrin selectivity of RGD-based agents, model structure and activity-selectivity relationships.     

Increased demyelination and axonal damage in metallothionein I+II-deficient mice during experimental autoimmune encephalomyelitis

Metallothioneins I+II (MT-I+II) are antioxidant, neuroprotective factors. We previously showed that MT-I+II deficiency during experimental autoimmune encephalomyelitis (EAE) leads to increased disease incidence and clinical symptoms. Moreover, the inflammatory response of macrophages and T cells, oxidative stress, and apoptotic cell death during EAE were increased by MT-I+II deficiency. We now show for the first time that demyelination and axonal damage are significantly increased in MT-I+II deficient mice during EAE. Furthermore, oligodendroglial regeneration, growth cone formation, and tissue repair including expression of trophic factors were significantly reduced in MT-I+II-deficient mice during EAE. Accordingly, MT-I+II have protective and regenerative roles in the brain. Received 31 October 2002; received after revision 23 November 2002; accepted 26 November 2002 RID="*" ID="*"Corresponding author. M. Penkowa and C. Espejo contributed equally to this paper.     

Design and evaluation of a diabody to improve protection against a potent scorpion neurotoxin

Diabodies are recombinant, dimeric, antibody-based molecules composed of two non-covalently associated single-chain antibody fragments that bind to an antigen in a divalent manner. In an attempt to develop more effective therapeutic molecules against scorpion venoms, we designed a diabody derived from monoclonal antibody 9C2, which neutralizes the toxicity of scorpion neurotoxin AahI in mammals. The recombinant diabody produced in the periplasm of Escherichia coli was purified to homogeneity in a single step by protein L-agarose affinity chromatography. It was functional, and possessed a high binding affinity to AahI (8 x 10(-11) M). The bivalence of the diabody was confirmed by size-exclusion chromatography, isoelectrofocussing and electron microscopic observations. Finally, the diabody showed high thermal stability in serum and demonstrated protective activity when injected intraperitoneally in mice experimentally envenomed with toxin AahI. In conclusion, the diabody format gives the 9C2 molecule advantageous properties that are particularly important for potential clinical applications in the treatment of envenomations.