Mo3S13 Chalcogel: A High-Capacity Electrode for Conversion-Based Li-Ion Batteries

Despite large theoretical energy densities, metal-sulfide electrodes for energy storage systems face several limitations that impact the practical realization. Here, we present the solution-processable, room temperature (RT) synthesis, local structures, and application of a sulfur-rich Mo3S13 chalcogel as a conversion-based electrode for lithium-sulfide batteries (LiSBs). The structure of the amorphous Mo3S13 chalcogel is derived through operando Raman spectroscopy, synchrotron X-ray pair distribution function (PDF), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) analysis, along with ab initio molecular dynamics (AIMD) simulations. A key feature of the three-dimensional (3D) network is the connection of Mo3S13 units through S-S bonds. Li/Mo3S13 half-cells deliver initial capacity of 1013 mAh g-1 during the first discharge. After the activation cycles, the capacity stabilizes and maintains 312 mAh g-1 at a C/3 rate after 140 cycles, demonstrating sustained performance over subsequent cycling. Such high-capacity and stability are attributed to the high density of (poly)sulfide bonds and the stable Mo-S coordination in Mo3S13 chalcogel. These findings showcase the potential of Mo3S13 chalcogels as metal-sulfide electrode materials for LiSBs.

Solution-processable mixed-anion cluster chalcohalide Rb6Re6S8I8 in a light-emitting diode

Rhenium chalcohalide cluster compounds are a photoluminescent family of mixed-anion chalcohalide cluster materials. Here we report the new material Rb6Re6S8I8, which crystallizes in the cubic space group Fm[Formula: see text]m and contains isolated [Re6S8I6]4- clusters. Rb6Re6S8I8 has a band gap of 2.06(5) eV and an ionization energy of 5.51(3) eV, and exhibits broad photoluminescence (PL) ranging from 1.01 eV to 2.12 eV. The room-temperature PL exhibits a PL quantum yield of 42.7% and a PL lifetime of 77 μs (99 μs at 77 K). Rb6Re6S8I8 is found to be soluble in multiple polar solvents including N,N-dimethylformamide, which enables solution processing of the material into films with thickness under 150 nm. Light-emitting diodes based on films of Rb6Re6S8I8 were fabricated, demonstrating the potential for this family of materials in optoelectronic devices.

Orientational analysis of atomic pair correlations in nanocrystalline indium oxide thin films

The application of grazing-incidence total X-ray scattering (GITXS) for pair distribution function (PDF) analysis using >50 keV X-rays from synchrotron light sources has created new opportunities for structural characterization of supported thin films with high resolution. Compared with grazing-incidence wide-angle X-ray scattering, which is only useful for highly ordered materials, GITXS/PDFs expand such analysis to largely disordered or nanostructured materials by examining the atomic pair correlations dependent on the direction relative to the surface of the supporting substrate. A characterization of nanocrystalline In2O3-derived thin films is presented here with in-plane-isotropic and out-of-plane-anisotropic orientational ordering of the atomic structure, each synthesized using different techniques. The atomic orientations of such films are known to vary based on the synthetic conditions. Here, an azimuthal orientational analysis of these films using GITXS with a single incident angle is shown to resolve the markedly different orientations of the atomic structures with respect to the planar support and the different degrees of long-range order, and hence, the terminal surface chemistries. It is anticipated that orientational analysis of GITXS/PDF data will offer opportunities to extend structural analyses of thin films by providing a means to qualitatively determine the major atomic orientation within nanocrystalline and, eventually, non-crystalline films.

Light-activated interlayer contraction in two-dimensional perovskites for high-efficiency solar cells

Understanding and tailoring the physical behaviour of halide perovskites under practical environments is critical for designing efficient and durable optoelectronic devices. Here, we report that continuous light illumination leads to >1% contraction in the out-of-plane direction in two-dimensional hybrid perovskites, which is reversible and strongly dependent on the specific superlattice packing. X-ray photoelectron spectroscopy measurements show that constant light illumination results in the accumulation of positive charges in the terminal iodine atoms, thereby enhancing the bonding character of inter-slab I-I interactions across the organic barrier and activating out-of-plane contraction. Correlated charge transport, structural and photovoltaic measurements confirm that the onset of the light-induced contraction is synchronized to a threefold increase in carrier mobility and conductivity, which is consistent with an increase in the electronic band dispersion predicted by first-principles calculations. Flux-dependent space-charge-limited current measurement reveals that light-induced interlayer contraction activates interlayer charge transport. The enhanced charge transport boosts the photovoltaic efficiency of two-dimensional perovskite solar cells up to 18.3% by increasing the device's fill factor and open-circuit voltage.

Signatures of Coherent Phonon Transport in Ultralow Thermal Conductivity Two-Dimensional Ruddlesden-Popper Phase Perovskites

An emerging class of methylammonium lead iodide (MAPbI₃)-based Ruddlesden-Popper (RP) phase perovskites, BA₂MA_n-1Pb_nI_3n+1 (n = 1-7), exhibit enhanced stability to environmental conditions relative to MAPbI₃, yet still degrade at elevated temperatures. We experimentally determine the thermal conductivities of these layered RP phases for n = 1-6, where n defines the number of repeated perovskite octahedra per layer. We measure thermal conductivities of 0.37 ± 0.13/0.12, 0.17 ± 0.08/0.07, 0.21 ± 0.05/0.04, and 0.19 ± 0.04/0.03 W/m·K in thin films of n = 1-4 and 0.08 ± 0.06/0.04, 0.06 ± 0.04/0.03, 0.06 ± 0.03/0.03, and 0.08 ± 0.07/0.04 W/m·K in single crystals of n = 3-6. With the exception of n = 1, these thermal conductivities are lower than the range of 0.34-0.50 W/m·K reported for single-crystal MAPbI₃. Reduced-order lattice dynamics modeling suggests that the initially decreasing trend of thermal conductivity in similarly oriented perovskites with increasing n may result from the transport properties of coherent phonons, emergent from the superstructure, that do not scatter at the interfaces of organic butylammonium chains and perovskite octahedra. Reduced group velocity of coherent phonons in n = 3-6, a consequence of band flattening in the phonon dispersion, is primarily responsible for their ultralow thermal conductivities. Similar effects on thermal conductivity have been experimentally demonstrated in deposited superlattices, but never in naturally defined materials such as RP phases. GIWAXS measurements reveal that higher n RP phase thin films are less orientationally controlled and therefore possess apparently elevated thermal conductivities relative to single crystals of the same n.

The 2D Halide Perovskite Rulebook: How the Spacer Influences Everything from the Structure to Optoelectronic Device Efficiency

Two-dimensional (2D) halide perovskites have emerged as outstanding semiconducting materials thanks to their superior stability and structural diversity. However, the ever-growing field of optoelectronic device research using 2D perovskites requires systematic understanding of the effects of the spacer on the structure, properties, and device performance. So far, many studies are based on trial-and-error tests of random spacers with limited ability to predict the resulting structure of these synthetic experiments, hindering the discovery of novel 2D materials to be incorporated into high-performance devices. In this review, we provide guidelines on successfully choosing spacers and incorporating them into crystalline materials and optoelectronic devices. We first provide a summary of various synthetic methods to act as a tutorial for groups interested in pursuing synthesis of novel 2D perovskites. Second, we provide our insights on what kind of spacer cations can stabilize 2D perovskites followed by an extensive review of the spacer cations, which have been shown to stabilize 2D perovskites with an emphasis on the effects of the spacer on the structure and optical properties. Next, we provide a similar explanation for the methods used to fabricate films and their desired properties. Like the synthesis section, we will then focus on various spacers that have been used in devices and how they influence the film structure and device performance. With a comprehensive understanding of these effects, a rational selection of novel spacers can be made, accelerating this already exciting field.

Nonclassical oxygen atom transfer reactions of an eight-coordinate dioxomolybdenum(vi) complex

Eight-coordinate MoO₂(DOPO^Q)₂ can donate two oxygen atoms to substrates such as phosphines in a four-electron nonclassical oxygen atom transfer reaction.

Alternative Organic Spacers for More Efficient Perovskite Solar Cells Containing Ruddlesden-Popper Phases

The halide perovskite Ruddlesden-Popper (RP) phases are a homologous layered subclass of solution-processable semiconductors that have aroused great attention, especially for developing long-term solar photovoltaics. They are defined as (A')₂(A)_n-1Pb_nX_3n+1 (A' = spacer cation, A = cage cation, and X = halide anion). The orientation control of low-temperature self-assembled thin films is a fundamental issue associated with the ability to control the charge carrier transport perpendicular to the substrate. Here we report new chemical derivatives designed from a molecular perspective using a novel spacer cation 3-phenyl-2-propenammonium (PPA) with conjugated backbone as a low-temperature strategy to assemble more efficient solar cells. First, we solved and refined the crystal structures of single crystals with the general formula (PPA)₂(FA_0.5MA_0.5)_n-1Pb_nI_3n+1 (n = 2 and 3, space group C2) using X-ray diffraction and then used the mixed halide (PPA)₂(Cs_0.05(FA_0.88MA_0.12)_0.95)_n-1Pb_n(I_0.88Br_0.12)_3n+1 analogues to achieve more efficient devices. While forming the RP phases, multiple hydrogen bonds between PPA and inorganic octahedra reinforce the layered structure. For films we observe that as the targeted layer thickness index increases from n = 2 to n = 4, a less horizontal preferred orientation of the inorganic layers is progressively realized along with an increased presence of high-n or 3D phases, with an improved flow of free charge carriers and vertical to substrate conductivity. Accordingly, we achieve an efficiency of 14.76% for planar p-i-n solar cells using PPA-RP perovskites, which retain 93.8 ± 0.25% efficiency with encapsulation after 600 h at 85 °C and 85% humidity (ISOS-D-3).

Long periodic ripple in a 2D hybrid halide perovskite structure using branched organic spacers

Two-dimensional (2D) halide perovskites have great promise in optoelectronic devices because of their stability and optical tunability, but the subtle effects on the inorganic layer when modifying the organic spacer remain unclear. Here, we introduce two homologous series of Ruddlesden-Popper (RP) structures using the branched isobutylammonium (IBA) and isoamylammonium (IAA) cations with the general formula (RA)2(MA) n-1Pb n I3n+1 (RA = IBA, IAA; MA = methylammonium n = 1-4). Surprisingly, the IAA n = 2 member results in the first modulated 2D perovskite structure with a ripple with a periodicity of 50.6 Å occurring in the inorganic slab diagonally to the [101] direction of the basic unit cell. This leads to an increase of Pb-I-Pb angles along the direction of the wave. Generally, both series show larger in-plane bond angles resulting from the additional bulkiness of the spacers compensating for the MA's small size. Larger bond angles have been shown to decrease the bandgap which is seen here with the bulkier IBA leading to both larger in-plane angles and lower bandgaps except for n = 2, in which the modulated structure has a lower bandgap because of its larger Pb-I-Pb angles. Photo-response was tested for the n = 4 compounds and confirmed, signaling their potential use in solar cell devices. We made films using an MACl additive which showed good crystallinity and preferred orientation according to grazing-incidence wide-angle scattering (GIWAXS). As exemplar, the two n = 4 samples were employed in devices with champion efficiencies of 8.22% and 7.32% for IBA and IAA, respectively.

Narrow-Bandgap Mixed Lead/Tin-Based 2D Dion-Jacobson Perovskites Boost the Performance of Solar Cells

The advent of the two-dimensional (2D) family of halide perovskites and their demonstration in 2D/three-dimensional (3D) hierarchical film structures broke new ground toward high device performance and good stability. The 2D Dion-Jacobson (DJ) phase halide perovskites are especially attractive in solar cells because of their superior charge transport properties. Here, we report on 2D DJ phase perovskites using a 3-(aminomethyl)piperidinium (3AMP) organic spacer for the fabrication of mixed Pb/Sn-based perovskites, exhibiting a narrow bandgap of 1.27 eV and a long carrier lifetime of 657.7 ns. Consequently, solar cells employing mixed 2D DJ 3AMP-based and 3D MA_0.5FA_0.5Pb_0.5Sn_0.5I₃ (MA = methylammonium, FA = formamidinium) perovskite composites as light absorbers achieve enhanced efficiency and stability, giving a power conversion efficiency of 20.09% with a high open-circuit voltage of 0.88 V, a fill factor of 79.74%, and a short-circuit current density of 28.63 mA cm^-2. The results provide an effective strategy to improve the performance of single-junction narrow-bandgap solar cells and, potentially, to give a highly efficient alternative to bottom solar cells in tandem devices.

In Situ Grazing-Incidence Wide-Angle Scattering Reveals Mechanisms for Phase Distribution and Disorientation in 2D Halide Perovskite Films

2D hybrid halide perovskites with the formula (A')₂ (A)_{n -1} Pb_n I_{3 n +1} have remarkable stability and promising efficiency in photovoltaic and optoelectronic devices, yet fundamental understanding of film formation, key to optimizing these devices, is lacking. Here, in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) is used to monitor film formation during spin-coating. This elucidates the general film formation mechanism of 2D halide perovskites during one-step spin-coating. There are three stages of film formation: sol-gel, oriented 3D, and 2D. Three precursor phases form during the sol-gel stage and transform to perovskite, first giving a highly oriented 3D-like phase at the air/liquid interface followed by subsequent nucleations forming slightly less oriented 2D perovskite. Furthermore, heating before crystallization leads to fewer nucleations and faster removal of the precursors, improving orientation. This outlines the primary causes of phase distribution and perpendicular orientation in 2D perovskite films and paves the way for rationally designed film fabrication techniques.

Neuropsychological, Psychiatric, and Functional Correlates of Clinical Trial Enrollment

Screen failure rates in Alzheimer's disease (AD) clinical trial research are unsustainable, with participant recruitment being a top barrier to AD research progress. The purpose of this project was to understand the neuropsychological, psychiatric, and functional features of individuals who failed screening measures for AD trials. Previously collected clinical data from 38 patients (aged 50-83) screened for a specific industry-sponsored clinical trial of MCI/early AD (Biogen 221AD302, [EMERGE]) were analyzed to identify predictors of AD trial screen pass/fail status. Worse performance on non-memory cognitive domains like crystalized knowledge, executive functioning, and attention, and higher self-reported anxiety, was associated with failing the screening visit for the EMERGE AD clinical trial, whereas we were not able to detect a relationship between screening status and memory performance, self-reported depression, or self-reported daily functioning. By identifying predictors of AD trial screen passing/failure, this research may influence decision-making about which patients are most likely to successfully enroll in a trial, thereby potentially lowering participant burden, maximizing study resources, and reducing costs.

(4NPEA)2PbI4 (4NPEA = 4-Nitrophenylethylammonium): Structural, NMR, and Optical Properties of a 3 × 3 Corrugated 2D Hybrid Perovskite

(4NPEA)₂PbI₄ (4NPEA = 4-nitrophenylethylammonium) is the first 3 × 3 corrugated 2D organic-Pb/I perovskite. The nitro groups are involved in cation-cation and cation-iodide interactions. The structure contains both highly distorted and near-ideal PbI₆ octahedra, consistent with the observation of two ²⁰⁷Pb NMR resonances, while the optical properties resemble those of other 2D perovskites with distorted PbI₆ octahedra.

Implementing Genomic Clinical Decision Support for Drug-Based Precision Medicine

The explosive growth of patient-specific genomic information relevant to drug therapy will continue to be a defining characteristic of biomedical research. To implement drug-based personalized medicine (PM) for patients, clinicians need actionable information incorporated into electronic health records (EHRs). New clinical decision support (CDS) methods and informatics infrastructure are required in order to comprehensively integrate, interpret, deliver, and apply the full range of genomic data for each patient.

Polymer-Encapsulated PC-12 Cells Demonstrate High-Affinity Uptake of Dopamine in Vitro and 18F-DOPA Uptake and Metabolism after Intracerebral Implantation in Nonhuman Primates

Intracranial implantation of polymer-encapsulated PC-12 cells has been shown to improve motor behavioral performance in animal models of Parkinson's disease. The purpose of this blinded study was to examine whether such improvement is associated with the active uptake and metabolism of dopamine precursors by intracerebrally implanted polymer-encapsulated PC-12 cells. In an in vitro experiment we demonstrate that 3H-dopamine uptake by PC-12 cells was 108 fmol/min × 106 cells, and that this uptake can be specifically blocked 88% by the addition of 10 nM of nomifensine. In the in vivo experiments, polymer-encapsulated PC-12 cells were implanted in four MPTP-treated monkeys into the left deep parietal white matter (R1) or left striatum (R2-4). A fifth MPTP-treated monkey (R5) served as a control and received left striatal implants of empty capsules. 18F-Dopa Positron Emission Tomography (PET) imaging was performed on each monkey before and after implantation surgery by blinded investigators. PET images obtained 5-13 wk after implantation demonstrated well delineated focal areas of high 18F-dopa uptake in R1, R2, and R4. The focal area of high 18F-dopa uptake in R1 precisely coregistered on a brain magnetic resonance image to the site of implantation. R3 (in whom the polymer-encapsulated PC-12 cells demonstrated poor cell survival upon explantation) and R5 (empty capsules) failed to demonstrate any area of increased 18F-dopa uptake in their PET images. Histological examination of the host brain revealed no sprouting of dopaminergic nerve terminals around the implantation sites of the polymer-encapsulated PC-12 cells. These results indicate that the previously noted behavioral improvement after intrastriatal implantation of polymer encapsulated PC-12 cells is at least in part due to their highly specific uptake and metabolism of dopamine precursors. Furthermore, these data suggest that polymer-encapsulated PC-12 cells can store, reuptake, and functionally replenish dopamine and therefore, may be an effective treatment for Parkinson's disease.

Clinical Pharmacogenetics Implementation Consortium Guidelines for HLA-B Genotype and Abacavir Dosing: 2014 update

The Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for HLA-B Genotype and Abacavir Dosing were originally published in April 2012. We reviewed recent literature and concluded that none of the evidence would change the therapeutic recommendations in the original guideline; therefore, the original publication remains clinically current. However, we have updated the Supplementary Material online and included additional resources for applying CPIC guidelines to the electronic health record. Up-to-date information can be found at PharmGKB (http://www.pharmgkb.org).

Regional muscle glucose uptake remains elevated one week after cessation of resistance training independent of altered insulin sensitivity response in older adults with type 2 diabetes

BACKGROUND

Aging is associated with a decline in skeletal muscle size.Muscle is critical both for mobility and glucose disposal. While resistance exercise (RE) increases muscle mass and function in the elderly, its role in improving glucose utilization is less clear.

AIMS

To investigate whether muscle size was linked with insulin sensitivity (IS) in elders with diabetes following RE and if regional muscle glucose uptake differed from systemic glucose utilization.

METHODS

Seven (68.4 ± 5.9 yr) adults with diabetes participated. After 16 weeks of RE, within 24 h (post 1) and after 1 week of no exercise (post 2), lean tissue cross-sectional area (CSA) and IS via glucose infusion rate (GIR) were assessed along with a standardized 18-F fluorodeoxyglucose (FDG)-positron emission tomography uptake value (SUV).

RESULTS

CSA increased between pre-test (108.5 ± 35.3 cm2) and post 1 (116.8 ± 40.9 cm2), p=0.02 and did not differ at post 2 (116.0 ± 39.3 cm2). GIR during the 40 mU/m2/min insulin clamp differed between pretest (22.0 ± 15.8 mg/kg/min) and post 1 (67.9 ± 72.8 mg/kg/min), and post 1 and post 2 (25.0 ± 27.2 mg/kg/min) but not between pre-test and post 2. GIR results during the 200 mU/m2/min insulin clamps also differed between pre-test and post 1, and post 1 and post 2 but not between pre-test and post 2. FDG-SUV increased between pre-test (1.1 ± 0.2) and post 1 (1.4 ± 0.3), and remained stable between post 1 and post 2 (1.4 ± 0.4).

CONCLUSION

RE that increased muscle size and FDG-SUV improved IS 24 h but not 1 week after exercise training.

Efficacy of intravascular catheter lock solutions containing preservatives in the prevention of microbial colonization

There is little published evidence regarding whether heparin lock solutions containing preservatives prevent catheter-related infections. However, adverse effects from preservative-containing flushes have been documented in neonates, leading many hospitals to avoid their use altogether. Infection control records from 1982 to 2008 at St. Jude Children's Research Hospital (SJCRH) were reviewed regarding the incidence of catheter-related infections and the use of preservative-containing intravenous locks. In addition, the antimicrobial activities of heparin lock solution containing the preservatives parabens (0.165%) or benzyl alcohol (0.9%), and 70% ethanol were examined against Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa and Candida albicans, and compared with preservative-free saline with and without heparin. Growth was assessed after exposure to test solutions for 0, 2, 4 and 24h at 35 °C. The activities of preservatives were assessed against both planktonic (free-floating) and sessile (biofilm-embedded) micro-organisms using the MBEC Assay. Infection control records revealed two periods of increased catheter-related infections, corresponding with two intervals when preservative-free heparin was used at SJCRH. Heparin solution containing preservatives demonstrated significant antimicrobial activity against both planktonic and sessile forms of all six microbial species. Ethanol demonstrated the greatest antimicrobial activity, especially following short incubation periods. Heparin lock solutions containing the preservatives parabens or benzyl alcohol, and 70% ethanol demonstrated significant antimicrobial activity against both planktonic and sessile micro-organisms commonly responsible for catheter-related infections. These findings, together with the authors' historical infection control experience, support the use of preservatives in intravenous lock solutions to reduce catheter related infections in patients beyond the neonatal period.

The relationship between inflammation-induced neuronal excitability and disrupted motor activity in the guinea pig distal colon

BACKGROUND

Colitis is associated with increased excitability of afterhyperpolarization neurons (AH neurons) and facilitated synaptic transmission in the myenteric plexus. These changes are accompanied by disrupted propulsive motility, particularly in ulcerated regions. This study examined the relationship between myenteric AH neuronal hyperexcitability and disrupted propulsive motility.

METHODS

The voltage-activated Na(+) channel opener veratridine, the intermediate conductance Ca(2+) -activated K(+) channel inhibitor TRAM-34 and the 5-HT(4) receptor agonist tegaserod were used to evaluate the effects of neuronal hyperexcitability and synaptic facilitation on propulsive motility in normal guinea pig distal colon. Because trinitrobenzene sulfonic acid (TNBS)-colitis-induced hyperexcitability of myenteric afferent neurons involves increases in hyperpolarization-activated, cyclic nucleotide-gated (HCN) channel activity, the HCN channel inhibitors Cs(+) and ZD7288 were used to suppress AH neuronal activity in TNBS-colitis.

KEY RESULTS

In non-inflamed preparations, veratridine halted propulsive motility (P<0.001). The rate of propulsive motor activity was significantly reduced following addition of TRAM-34 and tegaserod (P<0.001). In TNBS-inflamed preparations, in which motility was temporarily halted or obstructed at sites of ulceration, both Cs(+) and ZD7288 normalized motility through the inflamed regions. Immunohistochemistry studies demonstrated that the proportion of AH neurons in the myenteric plexus was unchanged in ulcerated regions, but there was a 10% reduction in total number of neurons per ganglion.

CONCLUSIONS AND INFERENCES

These findings support the concept that inflammation-induced neuroplasticity in myenteric neurons, involving changes in ion channel activity that lead to enhanced AH neuronal excitability, can contribute to impaired propulsive colonic motility.

Selective and divided visual attention: age-related changes in regional cerebral blood flow measured by H2(15)O PET

Regional cerebral blood flow (rCBF) was measured using H2(15)O and positron emission tomography (PET) to test the hypothesis that age-related changes in the pattern of rCBF activation would be greater under divided attention conditions than under selective attention conditions. Subjects were 24 right-handed men: 12 young adults (age 21-28 years), and 12 older adults (age 60-77 years). Measurement of rCBF was obtained during performance of three visual search task conditions, each of which involved viewing a series of nine-letter displays and making a two-choice button press response to each display. Analyses of subjects' mean reaction time and error rate confirmed that older adults' search performance was disproportionately impaired when it was necessary to divide attention among the display positions. The rCBF data indicated that attending selectively to a target letter in a known (central) location was not associated with cortical activation for either age group. The requirement to divide attention among the display positions led to rCBF activation in occipitotemporal, occipitoparietal, and prefrontal cortical regions. In the divided-attention condition, rCBF activation in the occipitotemporal pathway was relatively greater for young adults; activation in prefrontal regions was relatively greater for older adults. These differences in rCBF activation were related to search reaction time and suggest that, when attention was divided, young adults' performance relied primarily on letter identification processes, whereas older adults required the recruitment of additional forms of task control.

The effect of telephone counselling on reducing post-traumatic symptoms after mild traumatic brain injury: a randomised trial

BACKGROUND

Mild traumatic brain injury (MTBI) is a significant public health problem affecting approximately 1 million people annually in the USA. A total of 10-15% of individuals are estimated to have persistent post-traumatic symptoms. This study aimed to determine whether focused, scheduled telephone counselling during the first 3 months after MTBI decreases symptoms and improves functioning at 6 months.

METHODS

This was a two-group, parallel, randomised clinical trial with the outcome assessed by blinded examiner at 6 months after injury. 366 of 389 eligible subjects aged 16 years or older with MTBI were enrolled in the emergency department, with an 85% follow-up completion rate. Five telephone calls were completed, individualised for patient concerns and scripted to address education, reassurance and reactivation. Two composites were analysed, one relating to post-traumatic symptoms that developed or worsened after injury and their impact on functioning, the other related to general health status.

RESULTS

The telephone counselling group had a significantly better outcome for symptoms (6.6 difference in adjusted mean symptom score, 95% confidence interval (CI) 1.2 to 12.0), but no difference in general health outcome (1.5 difference in adjusted mean functional score, 95% CI 2.2 to 5.2). A smaller proportion of the treatment group had each individual symptom (except anxiety) at assessment. Similarly, fewer of the treatment group had daily functioning negatively impacted by symptoms with the largest differences in work, leisure activities, memory and concentration and financial independence.

CONCLUSIONS

Telephone counselling, focusing on symptom management, was successful in reducing chronic symptoms after MTBI.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, #NCT00483444.

The intermediate endpoint effect in logistic and probit regression

BACKGROUND

An intermediate endpoint is hypothesized to be in the middle of the causal sequence relating an independent variable to a dependent variable. The intermediate variable is also called a surrogate or mediating variable and the corresponding effect is called the mediated, surrogate endpoint, or intermediate endpoint effect. Clinical studies are often designed to change an intermediate or surrogate endpoint and through this intermediate change influence the ultimate endpoint. In many intermediate endpoint clinical studies the dependent variable is binary, and logistic or probit regression is used.

PURPOSE

The purpose of this study is to describe a limitation of a widely used approach to assessing intermediate endpoint effects and to propose an alternative method, based on products of coefficients, that yields more accurate results.

METHODS

The intermediate endpoint model for a binary outcome is described for a true binary outcome and for a dichotomization of a latent continuous outcome. Plots of true values and a simulation study are used to evaluate the different methods.

RESULTS

Distorted estimates of the intermediate endpoint effect and incorrect conclusions can result from the application of widely used methods to assess the intermediate endpoint effect. The same problem occurs for the proportion of an effect explained by an intermediate endpoint, which has been suggested as a useful measure for identifying intermediate endpoints. A solution to this problem is given based on the relationship between latent variable modeling and logistic or probit regression.

LIMITATIONS

More complicated intermediate variable models are not addressed in the study, although the methods described in the article can be extended to these more complicated models.

CONCLUSIONS

Researchers are encouraged to use an intermediate endpoint method based on the product of regression coefficients. A common method based on difference in coefficient methods can lead to distorted conclusions regarding the intermediate effect.

Activation of 5-HT1A receptors in the paragigantocellularis lateralis decreases shivering during cooling in the conscious piglet

Activation of 5-HT1A receptors in the medullary raphé decreases sympathetic outflow to thermoregulatory mechanisms, including brown adipose tissue (BAT), thermogenesis, and peripheral vasoconstriction when these mechanisms are previously activated with leptin, prostaglandins, or cooling. These same mechanisms are also inhibited during rapid eye movement (REM) sleep. It is not known whether shivering is also modulated by medullary raphé neurons. We previously showed in the conscious piglet that activation of 5-HT1A receptors with 8-OH-DPAT (DPAT) in the paragigantocellularis lateralis (PGCL), a medullary region lateral to the midline raphé that contains 5-HT neurons, decreases heart rate, body temperature and muscle activity during non-rapid eye movement (NREM) sleep. We therefore hypothesized that activation of 5-HT1A receptors in the PGCL would also attenuate shivering and peripheral vasoconstriction during cooling. During REM sleep in a cool environment, shivering, carbon dioxide production, and body temperature decreased, and ear capillary blood flow and ear skin temperature increased. Shivering associated with rapid cooling was attenuated after dialysis of DPAT into the PGCL. In animals maintained in a continuously cool environment, dialysis of DPAT into the PGCL attenuated shivering and decreased body temperature, but there were no significant increases in ear capillary blood flow or ear skin temperature. We conclude that both naturally occurring REM sleep and exogenous activation of 5-HT1A receptors in the PGCL are associated with a suspension of shivering during cooling. Our data are consistent with the hypothesis that 5-HT neurons in the PGCL facilitate oscillating spinal motor circuits involved in shivering but are less involved in modulating sympathetically mediated thermoregulatory mechanisms.

Should pharmacogenomic studies be required for new drug approval?

The field of pharmacogenetics has existed since the 1950s, when it was demonstrated that some drug effects could differ substantially among race and ethnic groups, and that some drug metabolizing enzyme activities were inherited. During the 1990s, application of molecular biology to the study of inherited drug-related phenotypes proved the genetic basis of several genetic polymorphisms. Genomic technology has now demonstrated that germline genetic variability among humans is extremely common. The combined weight of proven examples whereby pharmacogenetics affects drugs, and the possibility of even more examples being elucidated in the coming decades, dictates that pharmacogenetics be incorporated into the drug approval process. It is our contention that minimal pharmacogenetic testing should be required for all new drug applications to the Food and Drug Administration (FDA). This would include a requirement for germline DNA to be prospectively collected from all subjects participating in preapproval clinical trials. For drugs that are metabolized by enzymes whose genes have clearly inactivating polymorphisms, clinical trial participants should be genotyped for those polymorphisms.

Rapid dual-injection single-scan 13N-ammonia PET for quantification of rest and stress myocardial blood flows

Quantification of myocardial blood flows at rest and stress using 13N-ammonia PET is an established method; however, current techniques require a waiting period of about 1 h between scans. The objective of this study was to test a rapid dual-injection single-scan approach, where 13N-ammonia injections are administered 10 min apart during rest and adenosine stress. Dynamic PET data were acquired in six human subjects using imaging protocols that provided separate single-injection scans as gold standards. Rest and stress data were combined to emulate rapid dual-injection data so that the underlying activity from each injection was known exactly. Regional blood flow estimates were computed from the dual-injection data using two methods: background subtraction and combined modelling. The rapid dual-injection approach provided blood flow estimates very similar to the conventional single-injection standards. Rest blood flow estimates were affected very little by the dual-injection approach, and stress estimates correlated strongly with separate single-injection values (r=0.998, mean absolute difference=0.06 ml min-1 g-1). An actual rapid dual-injection scan was successfully acquired in one subject and further demonstrates feasibility of the method. This study with a limited dataset demonstrates that blood flow quantification can be obtained in only 20 min by the rapid dual-injection approach with accuracy similar to that of conventional separate rest and stress scans. The rapid dual-injection approach merits further development and additional evaluation for potential clinical use.

Operational specifications of the laser illuminated track etch scattering dosemeter reader

The personnel dosimetry operations team at the Los Alamos National Laboratory (LANL) has accepted the laser illuminated track etch scattering (LITES) dosemeter reader into its suite of radiation dose measurement instruments. The LITES instrument transmits coherent light from a He-Ne laser through the pertinent track etch foil and a photodiode measures the amount of light scattered by the etched tracks. A small beam stop blocks the main laser light, while a lens refocuses the scattered light into the photodiode. Three stepper motors in the current LITES system are used to position a carousel that holds 36 track etch dosemeters (TEDs). Preliminary work with the LITES system demonstrated the device had a linear response in counting foils subjected to exposures up to 50 mSv (5.0 rem). The United States Department of Energy requires that the annual general employee dose not exceed 50 mSv (5.0 rem). On a regular basis, LANL uses the Autoscan-60 reader system (Thermo Electron Corp.) for counting track etch dosemeters. However, LANL uses a 15 h etch process for CR-39 dosemeters, and this produces more and larger track etch pits than the 6 h etch used by many institutions. Therefore, LANL only uses the Autoscan-60 for measuring neutron dose equivalent up to exposure levels of approximately 3 mSv (300 mrem). The LITES system has a measured lower limit of detection of approximately 0.6 mSv (60 mrem), and it has a correlation coefficient of R (2) = 0.99 over an exposure range up to 500 mSv (50.0 rem). A series of blind studies were done using three methods: the Autoscan-60 system, manual counting by optical microscope and the LITES instrument. A collection of track etch dosemeters of unknown neutron dose equivalent (NDE) were analysed using the three methods, and the performance coefficient (PC) was calculated when the NDE became known. The Autoscan-60 and optical microscope methods had a combined PC = 0.171, and the LITES instrument had a PC = 0.194, where a PC less than or equal to 0.300 is considered satisfactory.

Use of verbal protocol analysis for identification of ADE signals

We describe the use of verbal protocol analysis for evaluating the textual signals used by pharmacists for detection of adverse drug events (ADEs). "Think aloud" technique was used to gain insight into how pharmacists reason about ADE occurrence, when reading patient progress notes. We used case-scenarios for five ADEs consisting of information regarding patient history, medications, laboratory results, vital signs and patient progress notes. Pharmacists extensively used information present in the progress notes to make inferences about ADEs.

Multisphere default spectra--solution spectrum and dosemeter response implications

Initial calibration of a multisphere spectroscopy system has been completed at Los Alamos National Laboratory using four standard calibration scenarios. Spectrum unfolding was performed using three methods of constructing the default spectrum: simple parameter models, Monte Carlo calculations and physical measurement. Comparisons of the resulting spectra for each solution method are presented. Implications of the spectral solutions upon dosemeter characterisation are addressed.

Direct text entry in electronic progress notes. An evaluation of input errors

OBJECTIVES

It is not uncommon that the introduction of a new technology fixes old problems while introducing new ones. The Veterans Administration recently implemented a comprehensive electronic medical record system (CPRS) to support provider order entry. Progress notes are entered directly by clinicians, primarily through keyboard input. Due to concerns that there may be significant, invisible disruptions to information flow, this study was conducted to formally examine the incidence and characteristics of input errors in the electronic patient record.

METHODS

Sixty patient charts were randomly selected from all 2,301 inpatient admissions during a 5-month period. A panel of clinicians with informatics backgrounds developed the review criteria. After establishing inter-rater reliability, two raters independently reviewed 1,891 notes for copying, copying errors, inconsistent text, inappropriate object insertion and signature issues.

RESULTS

Overall, 60% of patients reviewed had one or more input-related errors averaging 7.8 errors per patient. About 20% of notes showed evidence of copying, with an average of 1.01 error per copied note. Copying another clinician's note and making changes had the highest risk of error. Templating resulted in large amounts of blank spaces. Overall, MDs make more errors than other clinicians even after controlling for the number of notes.

CONCLUSIONS

Moving towards a more progressive model for the electronic medical record, where actions are recorded only once, history and physical information is encoded for use later, and note generation is organized around problems, would greatly minimize the potential for error.

Selected contribution: Effects of gender on reduced-size liver ischemia and reperfusion injury

Hepatic resection with concomitant periods of ischemia and reperfusion (I/R) is a common occurrence in resectional surgery as well as reduced-size liver transplantation (e.g., split liver or living donor transplantation). However, the I/R induced by these types of surgical manipulations may impair liver regeneration, ultimately leading to liver failure. The objectives of the study were to develop a murine model of reduced-size liver I/R and assess the role of gender in this model of hepatocellular injury. We found that 100% of female mice survived the surgery indefinitely, whereas all male mice had greater initial liver injury and died within 5 days after surgery. The protective effect observed in females appeared to be due to ovarian 17beta-estradiol, as ovariectomy of females or administration of a selective estrogen antagonist to female mice resulted in enhanced liver injury and greater mortality following reduced-size liver I/R. Conversely, 17beta-estradiol-treated male mice exhibited less hepatocellular damage and survived indefinitely. Taken together, these data demonstrate an estrogen-mediated protective pathway(s) that limits or attenuates hepatocellular injury induced by reduced-size liver I/R.

Positron emission tomography in evaluation of dementia: Regional brain metabolism and long-term outcome

CONTEXT

Deficits in cerebral glucose utilization have been identified in patients with cognitive dysfunction attributed to various disease processes, but their prognostic and diagnostic value remains to be defined.

OBJECTIVE

To assess the sensitivity and specificity with which cerebral metabolic patterns at a single point in time forecast subsequent documentation of progressive dementia.

DESIGN, SETTING, AND PATIENTS

Positron emission tomography (PET) studies of [(18)F]fluorodeoxyglucose in 146 patients undergoing evaluation for dementia with at least 2 years' follow-up for disease progression at the University of California, Los Angeles, from 1991 to 2000, and PET studies in 138 patients undergoing evaluation for dementia at an international consortium of facilities, with histopathological diagnoses an average of 2.9 years later, conducted from 1984 to 2000.

MAIN OUTCOME MEASURES

Regional distribution of [(18)F]fluorodeoxyglucose in each patient, classified by criteria established a priori as positive or negative for presence of a progressive neurodegenerative disease in general and of Alzheimer disease (AD) specifically, compared with results of longitudinal or neuropathologic analyses.

RESULTS

Progressive dementia was detected by PET with a sensitivity of 93% (191/206) and a specificity of 76% (59/78). Among patients with neuropathologically based diagnoses, PET identified patients with AD and patients with any neurodegenerative disease with a sensitivity of 94% and specificities of 73% and 78%, respectively. The negative likelihood ratio of experiencing a progressive vs nonprogressive course over the several years following a single negative brain PET scan was 0.10 (95% confidence interval, 0.06-0.16), and the initial pattern of cerebral metabolism was significantly associated with the subsequent course of progression overall (P<.001).

CONCLUSION

In patients presenting with cognitive symptoms of dementia, regional brain metabolism was a sensitive indicator of AD and of neurodegenerative disease in general. A negative PET scan indicated that pathologic progression of cognitive impairment during the mean 3-year follow-up was unlikely to occur.

Role of nitric oxide in inflammation

A number of laboratories have sought to elucidate the role of nitric oxide (NO) in both acute and chronic inflammatory diseases. It is now well appreciated that NO can influence many aspects of the inflammatory cascade ranging from its own expression to recruitment of leucocytes to the effected tissue. With the advent of mice selectively deficient in the various isoforms of nitric oxide synthase (NOS), the role that NO may play in various disease states can now be examined in vivo. One such syndrome that has gained much attention in recent years is ischaemia and reperfusion-induced tissue injury. Ischaemia-reperfusion (I/R) injury is an important clinical consideration in situations such as transplantation, trauma, liver or bowel resection and haemorrhagic shock. A hallmark of I/R is the production of reactive oxygen species (ROS) during the reperfusion phase and it is thought that the production of ROS mediate much of the post-ischaemic tissue injury. This review will examine the current state of knowledge regarding the regulatory mechanisms by which NO can influence various aspects of the inflammatory cascade as well as its role in a model of I/R injury in vivo.

Enhanced post-ischemic liver injury in iNOS-deficient mice: a cautionary note

The objective of this study was to assess the role of inducible nitric oxide synthase (iNOS) in ischemia- and reperfusion (I/R)-induced liver injury. We found that partial hepatic ischemia involving 70% of the liver resulted in a time-dependent increase in serum alanine aminotransferase (ALT) levels at 1-6 h following reperfusion. Liver injury at 1, 3, and 6 h post-ischemia was not due to the infiltration of neutrophils as assessed by tissue myeloperoxidase (MPO) activity and histopathology. iNOS-deficient mice subjected to the same duration of ischemia and reperfusion showed dramatic and significant increases in liver injury at 3 but not 6 h following reperfusion compared to their wild type controls. Paradoxically, iNOS mRNA expression was not detected in the livers of wild type mice at any point during the reperfusion period and pharmacological inhibition of iNOS using L-N(6)(iminoethyl)-lysine (L-NIL) did not exacerbate post-ischemic liver injury at any time post-reperfusion. These data suggest that iNOS deficiency produces unanticipated genetic alterations that renders these mice more sensitive to liver I/R-induced injury.

New advances in brain tumor imaging

During the period of this review, there has been continued use and development of neuroimaging techniques in brain tumor diagnosis and management. Although no monumental developments or improvements in neuroimaging techniques or technology have occurred, important studies continue to be published showing the clinical impact and utility of various neuroimaging techniques to improve the care of patients with brain tumors. Several studies have shown the power of functional neuroimaging techniques with both magnetic resonance imaging (MRI) and positron-emission tomography (PET) to map eloquent cortex and assist in the planning of surgical and radiation therapy. New nuclear imaging radiopharmaceuticals, including various PET ligands and single photon emission computed tomography (SPECT) agents, have also been developed and show their potential power in the evaluation of brain tumor patients. New MRI pulse sequences to improve image quality and shorten imaging time have also been developed. Several excellent reviews of the use of fluorodeoxyglucose (FDG)-PET and MRI techniques were also published. This article reviews the relevant and important neuroimaging literature related to brain tumor that was published during the defined time period of November 1, 1999 to October 31, 2000. Discussion is organized by modality, including nuclear imaging techniques (SPECT and PET) and MRI (pulse sequence development, contrast agent development, functional MRI developments, and general MRI-related information).

An apparatus and behavioral training protocol to conduct positron emission tomography (PET) neuroimaging in conscious rhesus monkeys

Nonhuman primates offer a unique resource in neuroimaging research, providing the opportunity to manipulate appropriate biological and behavioral variables under well-controlled experimental conditions in an animal model that is closely related to humans, both functionally and neuroanatomically. The present report describes the development and standardization of PET neuroimaging protocols in conscious rhesus monkeys and their application to characterize the acute effects of cocaine on cerebral blood flow. Specific attention was devoted to the development of an effective and comfortable head restraint device to be used in the imaging of conscious monkeys. The restraint device was designed to attach to a standard primate chair to facilitate frequent immobilization. Subjects received extensive behavioral training prior to neuroimaging in order to ensure their comfort and minimize potential stress associated with the imaging protocols. Functional changes in cerebral blood flow were characterized in three subjects with the positron-emitting tracer 15O water following acute i.v. administration of cocaine. Regions of interest were defined on MRI scans with a high degree of accuracy. Cocaine caused pronounced increases in cerebral blood flow at 5 min postinjection that diminished markedly within 25 min. The results document the feasibility to conduct PET neuroimaging studies of cerebral blood flow in conscious nonhuman primates. Extension of the methodology to include brain activation during behavioral studies could contribute significantly to the growing discipline of behavioral neuroscience.

Neural activity related to drug craving in cocaine addiction

BACKGROUND

Crack cocaine dependence and addiction is typically associated with frequent and intense drug wanting or craving triggered by internal or environmental cues associated with past drug use.

METHODS

Water O 15 positron emission tomography (PET) studies were used to localize alterations in synaptic activity related to cue-induced drug craving in 8 crack cocaine-dependent African American men. In a novel approach, script-guided imagery of autobiographical memories were used as individualized cues to internally generate a cocaine craving state and 2 control (ie, anger and neutral episodic memory recall) states during PET image acquisition.

RESULTS

The mental imagery of personalized drug use and anger-related scripts was associated with self-ratings of robust drug craving or anger, and comparable alterations in heart rate. Compared with the neutral imagery control condition, imagery-induced drug craving was associated with bilateral (right hemisphere amygdala activation greater than left) activation of the amygdala, the left insula and anterior cingulate gyrus, and the right subcallosal gyrus and nucleus accumbens area. Compared with the anger control condition, internally generated drug craving was associated with bilateral activation of the insula and subcallosal cortex, left hippocampus, and anterior cingulate cortex and brainstem. A brain-wide pixel-by-pixel search indicated significant positive and negative correlations between imagery-induced cocaine craving and regional cerebral blood flow (rCBF) in distributed sites.

CONCLUSIONS

The collected findings suggest the craving-related activation of a network of limbic, paralimbic, and striatal brain regions, including structures involved in stimulus-reward association (amygdala), incentive motivation (subcallosal gyrus/nucleus accumbens), and anticipation (anterior cingulate cortex).

Future directions in small animal imaging

The adaptation and development of imaging technologies for use in small animals has the potential to be a refinement with profound effects on how basic cancer research using animals is conducted. The authors describe how NCI funding is helping to advance research in this area.

Biodistribution and radiation dosimetry of the dopamine transporter ligand

18F-labeled 2 beta-carbomethoxy-3beta-(4-chlorophenyl)-8-(-2-fluoroethyl)nortropane ([18F]FECNT) is a recently developed dopamine transporter ligand with potential applications in patients with Parkinson's disease and cocaine addiction.

METHODS

Estimates of the effective dose equivalent and doses for specific organs were made using biodistribution data from 16 Sprague-Dawley rats and nine rhesus monkeys. PET images from two rhesus monkeys were used to calculate the residence time for the basal ganglia. The computer program MIRDOSE3 was used to calculate the dosimetry according to the methodology recommended by MIRD.

RESULTS

The basal ganglia were the targeted tissues receiving the highest dose, 0.11 mGy/MBq (0.39 rad/mCi). The effective dose equivalent was 0.018 mSv/MBq (0.065 rem/mCi), and the effective dose was 0.016 mSv/MBq (0.058 rem/mCi).

CONCLUSION

Our data show that a 185-MBq (5-mCi) injection of [18F]FECNT leads to an estimated effective dose of 3 mSv (0.3 rem) and an estimated dose to the target organ or tissue of 19.4 mGy (1.93 rad).

Neural correlates of maternal separation in rhesus monkeys

BACKGROUND

The neurobiological basis of stress and anxiety in primates remains poorly understood. In this study, we examined the neural response to a naturalistic social stressor: maternal separation. We used rhesus monkeys as an animal model because of their close phylogenetic affinity with humans.

METHODS

Six juvenile rhesus monkeys received [(18)F]-fluorodeoxyglucose positron emission tomography scans following 1) a period together with their mothers and again after separation from their mothers 2) with or 3) without visual contact. Image subtraction revealed brain regions that exhibited altered activity during separation. In addition, plasma cortisol concentrations obtained following each condition were tested for correlations with regional brain activity.

RESULTS

Maternal separation activated the right dorsolateral prefrontal cortex and the right ventral temporal/occipital lobe. There was also decreased activity in left dorsolateral prefrontal cortex associated with separation stress. Correlational analyses demonstrated these activated and deactivated regions to be positively and negatively correlated with cortisol, respectively. Additionally, correlational analyses revealed cortisol-related activation in brainstem areas previously implicated in stress and anxiety.

CONCLUSIONS

In juvenile rhesus monkeys, the stress of maternal separation is associated with activation in the right dorsolateral prefrontal cortex and ventral temporal/occipital lobes and decreased activity in the left dorsolateral prefrontal cortex.

In vivo imaging of gene expression

Imaging of gene expression is increasingly essential for cancer diagnosis, prediction of tumor response to various available therapies, and for monitoring response to therapy, whether it is gene or nongene therapy. Most of the work on developing techniques and methodologies for imaging gene expression has been performed in mice. Sophisticated small animal imaging technologies have been developed for this purpose. Imaging of gene expression in humans is still very limited. Nuclear medicine, positron-emission tomography, magnetic resonance imaging, and optical methods are the modalities that have shown preliminary utility in imaging gene expression. Two major imaging strategies have been investigated: using marker genes encoding either intracellular enzymes or cell-surface receptors. The first approach exploits the ability of certain enzymes to modify imaging prodrugs, so that tissue accumulation of such drugs reflects the expression. The second approach uses cell-surface expression of ligand-binding receptors that can be detected using imaging tracers. In this review, we summarize some of the imaging techniques that have been developed to detect gene expression.

FDG PET imaging in patients with pathologically verified dementia

The purpose of this study was to confirm with pathologic verification 2 beliefs related to Alzheimer's disease (AD): (a) the long-standing impression that bilateral temporo-parietal hypometabolism, as noted on FDG PET imaging, is the metabolic abnormality associated with Alzheimer's disease (AD) and (b) that the sensitivity, specificity, and diagnostic accuracy of the metabolic pattern of bilateral temporo-parietal hypometabolism allows differentiation between other degenerative causes of dementia.

METHODS

Twenty two individuals (8 women, 14 men) with difficult-to-characterize memory loss or dementia (using standard clinical criteria), and who eventually received pathologic confirmation of diagnosis, were evaluated. FDG PET brain scans were obtained and visually graded by an experienced nuclear medicine physician as to the presence of classic bilateral temporo-parietal hypometabolism as seen in Alzheimer's type dementia. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the metabolic pattern of bilateral temporo-parietal hypometabolism were determined using pathologic diagnosis as the gold standard.

RESULTS

The clinical diagnosis of possible or probable AD was determined as the primary cause of dementia in 12 patients. The sensitivity and specificity of the clinical diagnosis for probable AD were 63% and 100%, respectively. The sensitivity and specificity of the clinical diagnosis for possible and probable AD were 75% and 100%, respectively. The sensitivity, specificity, and diagnostic accuracy of bilateral temporo-parietal hypometabolism being associated with AD were 93%, 63%, and 82%, respectively.

CONCLUSION

This study confirms that bilateral temporo-parietal hypometabolism is indeed the classic metabolic abnormality associated with AD. Furthermore, in individuals with dementia whose FDG PET scans indicated a metabolic pattern other than bilateral temporo-parietal hypometabolism, a cause of dementia other than AD should be suspected. These observations may be of clinical importance in differentiating dementia syndromes. The sensitivity, specificity, and diagnostic accuracy of FDG PET are acceptable as tests to be used in the evaluation of dementia and particularly to confirm the clinical suspicion of AD.

Identification of MK-944a: a second clinical candidate from the hydroxylaminepentanamide isostere series of HIV protease inhibitors

Recent results from human clinical trials have established the critical role of HIV protease inhibitors in the treatment of acquired immune-deficiency syndrome (AIDS). However, the emergence of viral resistance, demanding treatment protocols, and adverse side effects have exposed the urgent need for a second generation of HIV protease inhibitors. The continued exploration of our hydroxylaminepentanamide (HAPA) transition-state isostere series of HIV protease inhibitors, which initially resulted in the identification of Crixivan (indinavir sulfate, MK-639, L-735,524), has now yielded MK-944a (L-756,423). This compound is potent, is selective, and competitively inhibits HIV-1 PR with a K(i) value of 0.049 nM. It stops the spread of the HIV(IIIb)-infected MT4 lymphoid cells at 25.0-50.0 nM, even in the presence of alpha(1) acid glycoprotein, human serum albumin, normal human serum, or fetal bovine serum. MK-944a has a longer half-life in several animal models (rats, dogs, and monkeys) than indinavir sulfate and is currently in advanced human clinical trials.