This study's purpose was to explore family caregivers' experiences while they waited placement of family members with dementia in long-term care and how they coped during this period of waiting and transition. In this exploratory descriptive qualitative study, interviews were conducted with 29 caregivers at entry to the placement wait-list and at 3 to 4-month intervals thereafter. Final interviews, with 15 caregivers, were conducted shortly after admission to long-term care. When "the waiting begins," the themes of crisis as initiator, synchronicity, control, and reciprocity emerged. "After placement" included the themes of deeply bonded relationships, attempting continuity, and sorting out the change. The findings provide new insight into family caregiver experiences during and after placement of a family member with dementia in long-term care. Clinicians must recognize that wherever services are provided, at home before placement or in institutions after placement, family caregivers must be incorporated as full partners in care.

SummaryNon-viral gene therapy is based on the use of plasmid expression vectors and chemical or physical plasmid DNA delivery systems. This review discusses the roles of cationic lipids as vectors for gene transfection, reviews different strategies employed to improve cationic lipids for in vivo use, and provides original results on the physicochemistry of lipoplexes. Cationic lipid/DNA delivery vehicles have evolved considerably since their initial gene transfection experiments. Much work has been carried out to investigate their structure/activity relationships, methods of formulation and physicochemical properties. Further work has also focused on enhancing and prolonging their stability in a physiological environment as well as increasing their sitespecific and tissue-specific interactions. Original data presented in this report confirm that cationic lipids associated to DNA form supramolecular lamellar structures, which protect DNA from serum DNAse degradation. The effect of formulation (and hence the size of the particles) on lipoplex in vivo circulation half-life and biodistribution is also discussed. A list of abbreviations can be found at the end of the review. Copyright  2004 John Wiley & Sons, Ltd.Keywords gene therapy; non-viral vectors; cationic lipids; liposomes Cationic lipids-structure/activity relationshipsExtensive reviewing has been focused on the various published structures of cationic lipids, which are composed of a cationic head (titrable amine or quaternary amine, guanidine, etc.), a linker, and a hydrophobic moiety (Figure 1). The hydrophobic moiety provides self-association to form either micelles or liposomes in the presence of a helper lipid such as dioleylphosphatidylethanolamine (DOPE). Much work has been carried out on modifying the different components of cationic lipids for use in gene transfection in order to try to determine if there is a 'best' length of chain (saturated or unsaturated, asymmetric or not), which type of spacer gives the desired function, plus the number and nature of cationic charges present and their molecular shape. Excellent reviews have covered the different aspects of structure/activity relationships of cationic lipids and a very short summary of some of the main points follows [1].The choice of lipid is predominantly between either a two hydrocarbon chain or a cholesterol moiety. Cholesterol has been found to offer rigidity to the lipid bilayer and there are two main examples of cationic lipids containing cholesterol as their lipid [2]; DC-Chol and the more recent BGTC, illustrated in Figure 2, will be described later. Cationic lipids with hydrocarbon chains as their lipid component have been very thoroughly researched. The most common types of chain lengths are C8 : 0 to C18 : 1 and are either linear and saturated or linear and mono-unsaturated. There

The rate of branch migration in doublestranded DNA has been measured by the use of a unique substrate formed by the action of the EcoRI restriction endonuclease on the dimeric figure-S configuration of the replicative form DNA of phage G4. The figureS and the X-form derived from it contain a junction of the kind postulated to occur in the Holliday structure and to be an essential feature of a number of models of recombination. In the X-form this junction can branch migrate to an irreversible terminal configuration consisting of two linear monomers. The disappearance of X-forms was measured by electron microscopy. A treatment of branch migration as a random walk process was developed to permit the determination of the rate of the intrinsic process, a step movement of the junction by a distance of one base pair. A value of about 6 kilobase pairs per sec at 370 was obtained. The figure-8 configuration of dimeric replicative form (RF) DNA of phages 4X174 and S13 was shown by Thompson et al. (1) to comprise up to 7% of the dimers. It was proposed to be an intermediate in recombination in these phages chiefly because it was assumed to be able to engage in branch migration (1, 2). A junction of the type present in the figure-8 is an essential feature of the Holliday structure (3), and its migration is basic to a number of models of recombination described in recent reviews (4-6). The figure-8 is, in fact, a Holliday structure for the simple, circular genome of the RF of the small DNA phages.Evidence that branch migration is a physically possible process was given by Lee et al. (7). They studied a repetitious DNA structure with single-stranded tails by electron microscopy and concluded from the distribution of tail lengths that branch migration had occurred. Kim et al. (8) provided similar evidence for double-stranded branch migration of the kind that occurs in the figure-8. Structures interpreted as involving both single-and double-stranded migration were observed by electron microscopy to result from recombination in phage T4 by Broker and Lehman (9, 10). They developed models showing the relevance of branch migration to recombination and suggested the figure-8, among other configurations, as an intermediate. Largely because of the reversibility of the direction of branch migration, the methods that have been used thus far cannot give information about the dynamics of the process or even provide more than indirect evidence that it can occur.The RF of phage G4 has one site per monomer for hydrolysis by the EcoRI restriction endonuclease. We have used this enzyme to convert figure-8 forms from G4-RF to an X-shaped configuration. These X-forms are a new type of substrate for studying branch migration because the migration terminates in an irreversible step, the formation of two linear monomers.We report here a preliminary study of branch migration in the X-form, including measurements of its rate. Electron Microscopy. Samples were prepared for electron microscopy as previously described (1). Some of the sprea...

ABSTRACT'. The objective of this study was to characterize the fatty acid biosynthetic pathway of the lactating human breast. Mixed cell populations, obtained by centrifugation of human milk, were enriched in breast epithelial cells by a selective adsorption procedure. Confirmation of the identity of the breast epithelial cells was obtained immunohistochemically. These viable breast epithelial cells incorporated radioactively labeled acetate predominantly into fatty acids with less than 16C atoms. The presence of the two key enzymes characteristic of the medium-chain fatty acid biosynthetic pathway of nonruminant~, fatty acid synthetase, and thioesterase 11, was demonstrated both qualitatively, by immunohistochemistry, and quantitatively, by enzyme assay. The results indicate that the lipogenic system of the human breast is qualitatively very similar to that of rats, mice, and rabbits, which also secrete milk fats containing medium-chain fatty acids. Quantitatively, however, the mammary fatty acid biosynthetic pathway appears to be less active in humans than in these other species. (Pediatr Res 19: 139-143, 1985) The presence of breast epithelial cells in human milk was first reported more than a quarter century ago (10). Although a number of investigators have been successful in culturing these cells (3,5,12,17,26,27,34), it appears that, to date, no serious attempt has been made to utilize such cells in studying metabolic and enzymological characteristics of the lactating human breast. We have recently attempted to use these cells in the study of the fatty acid biosynthetic pathway.Work in our laboratory with rodents has demonstrated that the mammary epithelium of these animals is uniquely able to synthesize the medium-chain fatty acids characteristic of milk fat (1, 2 1, 28). We and others (13-15, 19, 3 1, 32) have shown that the unique product specificity of the mammary gland lipogenic system in nonruminant mammals is attributable to the presence in the epithelium of a tissue-specific chain-terminating enzyme, medium-chain fatty acyl-S-4'-phosphopantetheine-fatty acid synthetase thioester hydrolase (trivial name, thioesterase 11).

Surface modification of cationic lipoplexes has been carried out by means of a postgrafting reaction. The original lipoplexes described comprise a cationic lipid, a neutral lipid, poly(ethylene glycol)-cholesterol (with or without a targeting ligand) and DNA. Modifying their surface via a chemical, postgrafting reaction did not alter their size (approximately 100 nm) nor their ability to compact DNA, but did give a reduced zeta potential (approximately 0 mV) to afford surface neutral particles. With the modified lipoplexes nonspecific NIH3T3 cell surface binding in vitro was inhibited. Intravenous injection of the neutralized lipoplexes in mice showed decreased accumulation of the particles in the lung as compared to PEGylated cationic lipoplexes. Tumor targeting was also achieved in vivo by the addition of an RGD-PEG-Cholesterol as a lipid-ligand in the postgrafted lipoplex formulation.