4f-electron localization in CexLa 1-xM In5 with M=Co, Rh, or Ir

de Haas-van Alphen measurements on Ce(x)La(1-x)MIn(5) yield contrasting types of behavior that depend on whether M=Co and Ir or M=Rh. A stronger x-dependent scattering in the case of M=Co and Ir is suggestive of a stronger relative coupling, J/W, of the conduction electrons to the 4f electrons, which would then account for the development of a heavy composite Fermi-liquid state as x-->1. The failure of a composite Fermi-liquid state to form for any x in the case of M= Rh is shown to be inconsistent with theoretical models that propose antiferromagnetism to result from spin-density-wave formation.

The contribution of three strong candidate schizophrenia susceptibility genes in demographically distinct populations

Here we characterize and compare the contribution of three recently identified strong candidate schizophrenia susceptibility genes; G72, neuregulin 1 (NRG1) and dystrobrevin-binding protein 1 (DTNBP1) in two independent datasets of patients with distinct genetic backgrounds. On the basis of corrected P-values from single- and multilocus transmission distortion tests our analysis provides no support for a contribution of G72, NRG1 or DTNBP1 in the tested samples. When transmission of individual haplotypes was considered, a picture more consistent with the original studies emerged, where transmission distortions in the same direction as the original samples and involving the same core haplotypes were observed for G72 and NRG1. Interestingly, whereas the NRG1 gene analysis was dominated by the presence of over-transmitted haplotypes, the G72 gene analysis was consistently dominated in both datasets by under-transmissions. Negative transmissions involved a core haplotype complementary to the originally detected over-transmitted haplotype, suggesting the presence of a protective variant within the G72 locus.

The dental health of people with schizophrenia

OBJECTIVE

To examine the dental health of community dwelling people with schizophrenia and to compare results with those in the general population.

METHOD

Dental health of 428 people with schizophrenia in six different areas of the UK was assessed by a self-report questionnaire.

RESULTS

Compared with the general population, significantly more of the younger patients were edentate (3-39% vs. 1-20%) and fewer had more than 20 teeth (70% vs. 83%). None of four dental health targets had been achieved in the patient population. More patients had last visited the dentist because of trouble with their teeth; fewer had visited for a check-up. Fewer patients cleaned their teeth daily; this group had more negative symptoms.

CONCLUSION

The dental health of people with schizophrenia is poor. Community mental health teams should encourage them to attend their community dentist regularly.

Quality of Life in Patients Treated with First-Line Antiretroviral Therapy Containing Nevirapine And/Or Efavirenz

Objective

To assess whether differences in safety profiles between nevirapine (NVP) and efavirenz (EFV), as observed in the 2NN study, translated into differences in ‘health related quality of life’ (HRQoL).

Design

A sub-study of the 2NN study, with antiretro-viral-naive patients randomly allocated to NVP (once or twice daily), EFV or NVP+EFV, in addition to stavudine and lamivudine.

Methods

Comparing differences in changes of HRQoL over 48 weeks as measured with the Medical Outcomes Study HIV Health Survey (MOS-HIV) questionnaire, using analysis of variance.

Results

The 2NN study enrolled 1216 patients. No validated questionnaires were available for 244 patients, and 55 patients had no HRQoL data at all, leaving 917 patients eligible for this sub-study. A total of 471 (51%) had HRQoL measurements both at baseline and week 48. The majority (69%) of patients without HRQoL measurements did, however, complete the study. The change in the physical health score (PHS) was 3.9 for NVP, 3.4 for EFV and 2.4 for NVP+EFV ( P=0.712). For the mental health score (MHS) these values were 6.1, 7.0 and 3.9, respectively ( P=0.098). A baseline plasma HIV-1 RNA concentration (pVL) ≥100 000 copies/ml and a decline in pVL (per log10) were independently associated with an increase of PHS. An increase of MHS was only associated with pVL decline. Patients experiencing an adverse event during follow-up had a comparable change in PHS but a significantly smaller change in MHS, compared with those without an adverse event.

Conclusions

First-line ART containing NVP and/or EFV leads to an improvement in HRQoL. The gain in HRQoL was similar for NVP and EFV, but slightly lower for the combination of these drugs.

Effects of inert volume-excluding macromolecules on protein fiber formation. II. Kinetic models for nucleated fiber growth

A sequential model for nucleated protein fiber formation is proposed that is similar in broad outline to models proposed previously (Thermodynamics of the Polymerization of Protein, Academic Press, New York, (1975); Biophys. J. 50 (1986) 583) but generalized to allow for thermodynamic nonideality resulting from a high degree of volume occupancy by inert macromolecular cosolutes (macromolecular crowding). The effect of volume occupancy on the rate of fiber formation is studied in the transition-state rate-limited regime through systematic variation of rate-limiting step (prenuclear oligomer formation, nucleus formation or fiber growth), shape of prenuclear oligomer, size of nucleus, extent of reversibility, nature of inert cosolute (hard globular particle or random coil polymer) and size of inert cosolute relative to that of fiber-forming protein. It is found that crowding can accelerate the rate of fiber formation by as much as several orders of magnitude. The extent of acceleration for a given degree of volume occupancy depends upon several factors, the most conspicuous of which is the stoichiometry of the nucleus. In contrast, the rate of redistribution of fiber length, which occurs on a much slower time scale than polymer formation, is found to be insensitive to the extent of crowding.

Silent Prions Lying in Wait: A Two-hit Model of Prion/Amyloid Formation and Infection

Diseases such as type 2 diabetes, Alzheimer's and Parkinson's are associated with the formation of amyloid. The transmissible spongiform encephalopathies, such as variant Creutzfeldt-Jakob disease, are believed to result from infectious forms of amyloid proteins termed prions. The ability of amyloid to initiate spontaneously and in the case of prions, to transfer successfully from one host to another, has been hard to fully rationalize. In this paper we use a mathematical model to explore the idea that it might be a combination of the presence of the prion/amyloid form and a change in the state of the host that allows the amyloid/prion to successfully initiate and propagate itself. We raise the intriguing possibility that potentially infectious amyloid may lie dormant in an apparently healthy individual awaiting a change in the state of the host or transmittal to a new more susceptible host. On this basis we make an analogy between prion/amyloid disease development and the two-hit model of cancer progression. We additionally raise the possibility that infectious amyloid strains may be characterized by a size distribution of length or radius.

Aging in Individuals With the FMR1 Mutation

Individuals with fragile X mental retardation 1 (FMR1) premutation (55 to 200 CGG repeats) are typically unaffected by fragile X syndrome. However, a subgroup of older males with the premutation have developed a neurological syndrome, which usually begins between 50 and 70 years and is associated with a progressive intention tremor and/or ataxia manifested by balance problems, frequent falling, and Parkinsonian symptoms, such as masked facies, intermittent resting tremor, and mild rigidity. This finding has been termed the fragile X-associated tremor/ataxia syndrome (FXTAS) and has brought focus to the aging process in individuals with the FMR1 mutation. The premutation is associated with elevated messenger RNA levels leading to the formation of intranuclear inclusions in neurons and astrocytes associated with FXTAS. This review is a summary of our experience with FXTAS in male carriers of the premutation.

A single approach to the recovery of DNA and firearm discharge residue evidence

The Laboratory of the Strathclyde Police Forensic Support Department extracts DNA from cellular material recovered from garments submitted as evidence. The standard method used an adhesive tape attached to a plastic or acetate support. This paper demonstrates a method whereby a single sample, recovered from clothing, can be examined for Firearm Discharge Residue and then extracted for DNA.

Optimization of recombinant aminolevulinate synthase production in Escherichia coli using factorial design

The production of recombinant Rhodobacter sphaeroides aminolevulinate (ALA) synthase was optimized in two strains of Escherichia coli: the wild-type strain MG1655, and a ptsG mutant AFP111. The effects of initial succinate, glucose and isopropyl-beta-d-thiogalactopyranoside (IPTG) concentrations and the time of induction on enzyme activity were studied. One-way analysis was used to approximate the optimal ranges for these factors, followed by a full factorial design to quantify the effects of each factor and the interactions between the factors. Initial succinate, glucose, and IPTG concentration were observed to be the key factors affecting ALA synthase activity with the optimal levels determined to be above 6 g/l succinate, 0 g/l glucose, and 0.10 mM IPTG. ALA synthase activity was generally lower with AFP111 than with MG1655, and the effect of these three key factors was also lower with AFP111 than with MG1655. Based on the full factorial design results, a fermentation was completed that yielded 296 mU/mg protein with a final ALA concentration of 5.2 g/l (39 mM).

Magnetic enhancement of superconductivity from electron spin domains

Since the discovery of superconductivity, there has been a drive to understand the mechanisms by which it occurs. The BCS (Bardeen-Cooper-Schrieffer) model successfully treats the electrons in conventional superconductors as pairs coupled by phonons (vibrational modes of oscillation) moving through the material, but there is as yet no accepted model for high-transition-temperature, organic or 'heavy fermion' superconductivity. Experiments that reveal unusual properties of those superconductors could therefore point the way to a deeper understanding of the underlying physics. In particular, the response of a material to a magnetic field can be revealing, because this usually reduces or quenches superconductivity. Here we report measurements of the heat capacity and magnetization that show that, for particular orientations of an external magnetic field, superconductivity in the heavy-fermion material CeCoIn(5) is enhanced through the magnetic moments (spins) of individual electrons. This enhancement occurs by fundamentally altering how the superconducting state forms, resulting in regions of superconductivity alternating with walls of spin-polarized unpaired electrons; this configuration lowers the free energy and allows superconductivity to remain stable. The large magnetic susceptibility of this material leads to an unusually strong coupling of the field to the electron spins, which dominates over the coupling to the electron orbits.

Macromolecular crowding: qualitative and semiquantitative successes, quantitative challenges

The concept of excluded volume and the theory of effects of excluded volume on the equilibria and rates of macromolecular reactions in fluid media containing high total concentrations of macromolecules ('crowded' media) are summarized. Reports of experimental studies of crowding effects published during the last year are tabulated. Limitations of current excluded volume theory are discussed, and a determination is made of conditions under which this theory may and may not be validly applied. Recently suggested novel approaches to quantitative analysis of crowding phenomena, which may help to overcome some of the limitations of current theory, are summarized.

Genome-wide scan in a large complex pedigree with predominantly male schizophrenics from the island of Kosrae: evidence for linkage to chromosome 2q

It is widely accepted that founder populations hold promise for mapping loci for complex traits. However, the outcome of these mapping efforts will most likely depend on the individual demographic characteristics and historical circumstances surrounding the founding of a given genetic isolate. The 'ideal' features of a founder population are currently unknown. The Micronesian islandic population of Kosrae, one of the four islands comprising the Federated States of Micronesia (FSM), was founded by a small number of settlers and went through a secondary genetic 'bottleneck' in the mid-19th century. The potential for reduced etiological (genetic and environmental) heterogeneity, as well as the opportunity to ascertain extended and statistically powerful pedigrees makes the Kosraen population attractive for mapping schizophrenia susceptibility genes. Our exhaustive case ascertainment from this islandic population identified 32 patients who met DSM-IV criteria for schizophrenia or schizoaffective disorder. Three of these were siblings in one nuclear family, and 27 were from a single large and complex schizophrenia kindred that includes a total of 251 individuals. One of the most startling findings in our ascertained sample was the great difference in male and female disease rates. A genome-wide scan provided initial suggestive evidence for linkage to markers on chromosomes 1, 2, 3, 7, 13, 15, 19, and X. Follow-up multipoint analyses gave additional support for a region on 2q37 that includes a schizophrenia locus previously identified in another small genetic isolate, with a well-established recent genealogical history and a small number of founders, located on the eastern border of Finland. In addition to providing further support for a schizophrenia susceptibility locus at 2q37, our results highlight the analytic challenges associated with extremely large and complex pedigrees, as well as the limitations associated with genetic studies of complex traits in small islandic populations.

The effects of Tubulin denaturation on the characterization of its polymerization behavior

We report here upon a simulation study examining the effect of a dynamic mode of tubulin denaturation upon the kinetic and thermodynamic characterisation of the polymer formed for two idealized models of a tubulin polymerization reaction: (i) an irreversibly polymerizing system; and (ii) a reversibly polymerizing system. The effects of each denaturation mode upon the two model systems behavior are highlighted by interpretation of the data in terms of the classical Oosawa reversible condensation polymerization model. We reveal here findings which suggest that the measurement strategy in concert with Tubulin's instability over the time course of the experiment may bias the results obtained so as to make an irreversible system's behavior conform to the equilibrium model or alternatively distort the results obtained from a truly reversible system to produce values of the critical concentration quite seriously in error. It was also found that Tubulin denaturation may seriously distort parameter estimates gained from a kinetic characterization of the system (e.g. nucleus size and growth rate constant).

Heavy-mass fermi liquid near a ferromagnetic instability in layered ruthenates

Low temperature magnetic, thermal, and transport measurements in Ca2-xSrxRuO4 clarify the appearance of a cluster glass phase, after the evolution of a nearly ferromagnetic heavy-mass Fermi liquid from the spin-triplet superconductor Sr2RuO4. As the Mott transition is approached across a 2nd-order structural transition, both the magnetization and specific heat decrease considerably while the transport scattering rate diverges. A metamagnetic transition to a highly spin polarized state, with a local moment S=1/2, is observed. We argue that an orbital rearrangement with Ca substitution changes itinerant ferromagnetism to antiferromagnetism of localized moments.

On the role of the macromolecular phase transitions in biology in response to change in solution volume or macromolecular composition: action as an entropy buffer

We have used numerical simulation to demonstrate the potential for macromolecular precipitate solution phase transitions existing within the cell, to play a role in the minimization of changes in location or quaternary state of other macromolecular components, predicted to accompany changes in cell volume. For our modeling we have employed thermodynamic relations that take into account the large effects upon the thermodynamic activity coefficient produced by a solution environment that is highly volume occupied due to the presence of high concentrations of soluble macromolecule. The theoretical approach adopted, along with the simulated results, provide a framework for the interpretation of certain proteins' behavior (e.g. cytoskeletal elements such as tubulin and actin and possibly some prion structures) in response to cell volume change.

Effects of inert volume-excluding macromolecules on protein fiber formation. I. Equilibrium models

The equilibrium Oosawa-Asakura model for nucleated assembly of rod-like protein fibers is recast in terms of dimensionless (scaled) quantities. The model is then generalized to treat arbitrarily large deviations from thermodynamic ideality arising from high fractional volume occupancy by an inert protein or polymer. Each state of association of the self-associating protein is modeled as an equivalent rigid convex particle (sphere or spherocylinder) and the crowding species is modeled either as an equivalent sphere or cylindrical rod. The resulting conservation of mass relation is readily solved to yield the fractional abundance of monomer, from which the entire equilibrium distribution of oligomeric species can be calculated, either directly or through the use of an additional scaling relationship. Results indicating the potential effect of volume occupancy on the equilibrium solubility of the self-associating protein and upon the equilibrium distribution of polymer size are presented. It is found that the fractional (logarithmic) change in both solubility and in the breadth of the polymer size distribution scale almost linearly with the fractional (logarithmic) change in the thermodynamic activity of monomer.

Magnetization in the ultraquantum limit

The magnetization below and far above the quantum limit for small Fermi surface orbits has been measured in the metallic compound LaRhIn(5). The magnetization due to a pocket of Fermi surface that comprises less than 1 part in 10(4) of the total Brillouin zone volume, and for which the quantum limit is approximately 7 T, leads to the appearance of an overall sample magnetic moment at fields between 7 and 32 T. This moment arises from diamagnetic currents produced by electrons in the ultraquantum limit. A model calculation of the origin and magnitude of the effect is in excellent agreement with the measured field dependence of the induced magnetization.