Interaction between parental psychosis and early motor development and the risk of schizophrenia in a general population birth cohort.

BACKGROUND: Delayed motor development in infancy and family history of psychosis are both associated with increased risk of schizophrenia, but their interaction is largely unstudied. AIM: To investigate the association of the age of achieving motor milestones and parental psychosis and their interaction in respect to risk of schizophrenia. METHODS: We used data from the general population-based prospective Northern Finland Birth Cohort 1966 (n=10,283). Developmental information of the cohort members was gathered during regular visits to Finnish child welfare clinics. Several registers were used to determine the diagnosis of schizophrenia among the cohort members and psychosis among the parents. Altogether 152 (1.5%) individuals had schizophrenia by the age of 46 years, with 23 (15.1%) of them having a parent with psychosis. Cox regression analysis was used in analyses. RESULTS: Parental psychosis was associated (P<0.05) with later achievement of holding the head up, grabbing an object, and walking without support. In the parental psychosis group, the risk for schizophrenia was increased if holding the head up (hazard ratio [HR]: 2.46; degrees of freedom [df]=1; 95% confidence interval [95% CI]: 1.07-5.66) and touching the thumb with the index finger (HR: 1.84; df=1; 95% CI: 1.11-3.06) was later. In the group without parental psychosis, a delay in the following milestones increased the risk of schizophrenia: standing without support and walking without support. Parental psychosis had an interaction with delayed touching thumb with index finger (HR: 1.87; df=1; 95% CI: 1.08-3.25) when risk of schizophrenia was investigated. CONCLUSIONS: Parental psychosis was associated with achieving motor milestones later in infancy, particularly the milestones that appear early in a child's life. Parental psychosis and touching the thumb with the index finger had a significant interaction on risk of schizophrenia. Genetic risk for psychosis may interact with delayed development to raise future risk of schizophrenia, or delayed development may be a marker of other risk processes that interact with genetic liability to cause later schizophrenia.

Targeting of biotinylated compounds to its target tissue using a low-density lipoprotein receptor-avidin fusion protein.

The very high binding affinity of avidin to biotin is one of the highest to occur in nature. We constructed a fusion protein composed of avidin and the endocytotic LDL receptor in order to target biotinylated molecules to cells of the desired tissues. In addition to the native avidin, charge-mutated and nonglycosylated avidins were utilized as part of the fusion proteins, in order to modify its properties. All of the fusion protein versions retained the biotin-binding capacity. Although the specificity was not increased, however, fusion proteins composed of natural avidin and nonglycosylated avidin bound most efficiently to the biotinylated ligands. Fluorescence microscopy and atomic force microscopy studies revealed the expression of the fusion protein on cell membranes, and demonstrated specific and high-affinity binding of biotin to the low-density lipoprotein receptor (LDLR)-avidin fusion protein in vitro. Additionally, systemically administered biotinylated ligand targeted with high specificity the intracerebral tumors of rats that were expressing fusion protein after the virus-mediated gene transfer. These results suggest that local gene transfer of the fusion protein to target tissues may offer a novel tool for the delivery of biotinylated molecules in vitro and in vivo for therapeutic and imaging purposes.

Biotin induces tetramerization of a recombinant monomeric avidin. A model for protein-protein interactions.

Chicken avidin, a homotetramer that binds four molecules of biotin was converted to a monomeric form by successive mutations of interface residues to alanine. The major contribution to monomer formation was the mutation of two aspartic acid residues, which together account for ten hydrogen bonding interactions at the 1-4 interface. Mutation of these residues, together with the three hydrophobic residues at the 1-3 interface, led to stable monomer formation in the absence of biotin. Upon addition of biotin, the monomeric avidin reassociated to the tetramer, which exhibited properties similar to those of native avidin, with respect to biotin binding, thermostability, and protease resistance. To our knowledge, these unexpected results represent the first example of a small monovalent ligand that induces oligomerization of a monomeric protein. This study may suggest a biological role for low molecular weight ligands in inducing oligomerization and in maintaining the stability of multimeric protein assemblies.

Cultural challenges in end-of-life care: reflections from focus groups' interviews with hospice staff in Stockholm.

Cultural challenges in end-of-life care: reflections from focus groups' interviews with hospice staff in Stockholm During the past few decades, Swedish society has changed from a society with a few ethnic groups to one with over a hundred groups of different ethnic backgrounds, languages and religions. As society is becoming increasingly multicultural, cultural issues are also becoming an important feature in health care, particularly in end-of-life care where the questions of existential nature are of great importance. However, cultural issues in health care, especially at hospices, have not been studied sufficiently in Sweden. The purpose of this study was to gather reflections about cultural issues among hospice staff after a 3-day seminar in multicultural end-of-life care, by using a qualitative focus groups method. The 19 participants (majority nurses) were divided into three groups, one per hospice unit. A discussion guide was developed with the following themes: 1) post-training experiences of working with patients with multicultural background; 2) experiences gained by participating in the course of multicultural end-of-life care; 3) post-training reflections about one's own culture; 4) ideas or thoughts regarding work with patients from other cultures arising from the training; and 5) the need for further training in multicultural end-of-life care. One of the study's main findings was that to better understand other cultures it is important to raise awareness about the staff's own culture and to pay attention to culture especially in the context of the individual. The findings from focus groups provide insight regarding the need for planning flexible training in cultural issues to match the needs of the staff at the hospice units studied.

Recombinant NeutraLite avidin: a non-glycosylated, acidic mutant of chicken avidin that exhibits high affinity for biotin and low non-specific binding properties.

A recombinant non-glycosylated and acidic form of avidin was designed and expressed in soluble form in baculovirus-infected insect cells. The mutations were based on the same principles that guided the design of the chemically and enzymatically modified avidin derivative, known as NeutraLite Avidin. In this novel recombinant avidin derivative, five out of the eight arginine residues were replaced with neutral amino acids, and two of the lysine residues were replaced by glutamic acid. In addition, the carbohydrate-bearing asparagine-17 residue was altered to an isoleucine, according to the known sequences of avidin-related genes. The resultant mutant protein, termed recombinant NeutraLite Avidin, exhibited superior properties compared to those of avidin, streptavidin and the conventional NeutraLite Avidin, prepared by chemo-enzymatic means. In this context, the recombinant mutant is a single molecular species, which possesses strong biotin-binding characteristics. Due to its acidic pI, it is relatively free from non-specific binding to DNA and cells. The recombinant NeutraLite Avidin retains seven lysines per subunit, which are available for further conjugation and derivatization.

Mutation of a critical tryptophan to lysine in avidin or streptavidin may explain why sea urchin fibropellin adopts an avidin-like domain.

Sea urchin fibropellins are epidermal growth factor homologues that harbor a C-terminal domain, similar in sequence to hen egg-white avidin and bacterial streptavidin. The fibropellin sequence was used as a conceptual template for mutation of designated conserved tryptophan residues in the biotin-binding sites of the tetrameric proteins, avidin and streptavidin. Three different mutations of avidin, Trp-110-Lys, Trp-70-Arg and the double mutant, were expressed in a baculovirus-infected insect cell system. A mutant of streptavidin, Trp-120-Lys, was similarly expressed. The homologous tryptophan to lysine (W-->K) mutations of avidin and streptavidin were both capable of binding biotin and biotinylated material. Their affinity for the vitamin was, however, significantly reduced: from K(d) approximately 10(-15) M of the wild-type tetramer down to K(d) approximately 10(-8) M for both W-->K mutants. In fact, their binding to immobilized biotin matrices could be reversed by the presence of free biotin. The Trp-70-Arg mutant of avidin bound biotin very poorly and the double mutant (which emulates the fibropellin domain) failed to bind biotin at all. Using a gel filtration fast-protein liquid chromatography assay, both W-->K mutants were found to form stable dimers in solution. These findings may indicate that mimicry in the nature of the avidin sequence and fold by the fibropellins is not designed to generate biotin-binding, but may serve to secure an appropriate structure for facilitating dimerization.

Engineering of chicken avidin: a progressive series of reduced charge mutants.

Avidin, a positively charged egg-white glycoprotein, is a widely used tool in biotechnological applications because of its ability to bind biotin strongly. The high pI of avidin (approximately 10.5), however, is a hindrance in certain applications due to non-specific (charge-related) binding. Here we report a construction of a series of avidin charge mutants with pIs ranging from 9.4 to 4.7. Rational design of the avidin mutants was based on known crystallographic data together with comparative sequence alignment of avidin, streptavidin and a set of avidin-related genes which occur in the chicken genome. All charge mutants retained the ability to bind biotin tightly according to optical biosensor interaction analysis. In most cases, their thermal stability characteristics were indistinguishable from those of the wild-type avidin. Our results demonstrate that the charge properties of avidin can be modified without disturbing the crucial biotin-binding activity.