Interior and surface of monomeric proteins

The solvent-accessible surface area (As) of 46 monomeric proteins is calculated using atomic co-ordinates from high-resolution and well-refined crystal structures. The As of these proteins can be determined to within 1 to 2% and that of their individual residues to within 10 to 20%. The As values of proteins are correlated with their molecular weight (Mr) in the range 4000 to 35,000: the power law As = 6.3 M0.73 predicts protein As values to within 4% on average. The average water-accessible surface is found to be 57% non-polar, 24% polar and 19% charged, with 5% root-mean-square variations. The molecular surface buried inside the protein is 58% non-polar, 39% polar and 4% charged. The buried surface contains more uncharged polar groups (mostly peptides) than the surface that remains accessible, but many fewer charged groups. On average, 15% of residues in small proteins and 32% in larger ones may be classed as "buried residues", having less than 5% of their surface accessible to the solvent. The accessibilities of most other residues are evenly distributed in the range 5 to 50%. Although the fraction of buried residues increases with molecular weight, the amino acid compositions of the protein interior and surface show no systematic variation with molecular weight, except for small proteins that are often very rich in buried cysteines. From amino acid compositions of protein surfaces and interiors we calculate an effective coefficient of partition for each type of residue, and derive an implied set of transfer free energy values. This is compared with other sets of partition coefficients derived directly from experimental data. The extent to which groups of residues (charged, polar and non-polar) are buried within proteins correlates well with their hydrophobicity derived from amino acid transfer experiments. Within these three groups, the correlation is low.

The origin of mutants

Nucleic acids are replicated with conspicuous fidelity. Infrequently, however, they undergo changes in sequence, and this process of change (mutation) generates the variability that allows evolution. As the result of studies of bacterial variation, it is now widely believed that mutations arise continuously and without any consideration for their utility. In this paper, we briefly review the source of this idea and then describe some experiments suggesting that cells may have mechanisms for choosing which mutations will occur.

Language comprehension in language-learning impaired children improved with acoustically modified speech

A speech processing algorithm was developed to create more salient versions of the rapidly changing elements in the acoustic waveform of speech that have been shown to be deficiently processed by language-learning impaired (LLI) children. LLI children received extensive daily training, over a 4-week period, with listening exercises in which all speech was translated into this synthetic form. They also received daily training with computer "games" designed to adaptively drive improvements in temporal processing thresholds. Significant improvements in speech discrimination and language comprehension abilities were demonstrated in two independent groups of LLI children.

Temporal processing deficits of language-learning impaired children ameliorated by training

Children with language-based learning impairments (LLIs) have major deficits in their recognition of some rapidly successive phonetic elements and nonspeech sound stimuli. In the current study, LLI children were engaged in adaptive training exercises mounted as computer "games" designed to drive improvements in their "temporal processing" skills. With 8 to 16 hours of training during a 20-day period, LLI children improved markedly in their abilities to recognize brief and fast sequences of nonspeech and speech stimuli.

Comparison of first-line antiretroviral therapy with regimens including nevirapine, efavirenz, or both drugs, plus stavudine and lamivudine: a randomised open-label trial, the 2NN Study

BACKGROUND

The 2NN Study was a randomised comparison of the non-nucleoside reverse-transcriptase inhibitors (NNRTI) nevirapine and efavirenz.

METHODS

In this multicentre, open-label, randomised trial, 1216 antiretroviral-therapy-naive patients were assigned nevirapine 400 mg once daily, nevirapine 200 mg twice daily, efavirenz 600 mg once daily, or nevirapine (400 mg) and efavirenz (800 mg) once daily, plus stavudine and lamivudine, for 48 weeks. The primary endpoint was the proportion of patients with treatment failure (less than 1 log(10) decline in plasma HIV-1 RNA in the first 12 weeks or two consecutive measurements of more than 50 copies per mL from week 24 onwards, disease progression [new Centers for Disease Control and Prevention grade C event or death], or change of allocated treatment). Analyses were by intention to treat.

FINDINGS

Treatment failure occurred in 96 (43.6%) of 220 patients assigned nevirapine once daily, 169 (43.7%) of 387 assigned nevirapine twice daily, 151 (37.8%) of 400 assigned efavirenz, and 111 (53.1%) of 209 assigned nevirapine plus efavirenz. The difference between nevirapine twice daily and efavirenz was 5.9% (95% CI -0.9 to 12.8). There were no significant differences among the study groups in the proportions with plasma HIV-1 RNA concentrations below 50 copies per mL at week 48 (p=0.193) or the increases in CD4-positive cells (p=0.800). Nevirapine plus efavirenz was associated with the highest frequency of clinical adverse events, and nevirapine once daily with significantly more hepatobiliary laboratory toxicities than efavirenz. Of 25 observed deaths, two were attributed to nevirapine.

INTERPRETATION

Antiretroviral therapy with nevirapine or efavirenz showed similar efficacy, so triple-drug regimens with either NNRTI are valid for first-line treatment. There are, however, differences in safety profiles. Combination of nevirapine and efavirenz did not improve efficacy but caused more adverse events.

Surface, subunit interfaces and interior of oligomeric proteins

The solvent-accessible surface area (As) of 23 oligomeric proteins is calculated using atomic co-ordinates from high-resolution and well-refined crystal structures. As is correlated with the protein molecular weight, and a power law predicts its value to within 5% on average. The accessible surface of the average oligomer is similar to that of monomeric proteins in its hydropathy and amino acid composition. The distribution of the 20 amino acid types between the protein surface and its interior is also the same as in monomers. Interfaces, i.e. surfaces involved in subunit contacts, differ from the rest of the subunit surface. They are enriched in hydrophobic side-chains, yet they contain a number of charged groups, especially from Arg residues, which are the most abundant residues at interfaces except for Leu. Buried Arg residues are involved in H-bonds between subunits. We counted H-bonds at interfaces and found that several have none, others have one H-bond per 200 A2 of interface area on average (1 A = 0.1 nm). A majority of interface H-bonds involve charged donor or acceptor groups, which should make their contribution to the free energy of dissociation significant, even when they are few. The smaller interfaces cover about 700 A2 of the subunit surface. The larger ones cover 3000 to 10,000 A2, up to 40% of the subunit surface area in catalase. The lower value corresponds to an estimate of the accessible surface area loss required for stabilizing subunit association through the hydrophobic effect alone. Oligomers with small interfaces have globular subunits with accessible surface areas similar to those of monomeric proteins. We suggest that these oligomers assemble from preformed monomers with little change in conformation. In oligomers with large interfaces, isolated subunits should be unstable given their excessively large accessible surface, and assembly is expected to require major structural changes.

Risks for incident human papillomavirus infection and low-grade squamous intraepithelial lesion development in young females

CONTEXT

Low-grade squamous intraepithelial lesions (LSILs) have been described as a benign cytological consequence of active human papillomavirus (HPV) replication. Several studies have reported that certain behavioral and biological risks exist for LSIL, suggesting that HPV alone is not sufficient for the development of LSIL. However, because most of these studies have been cross-sectional, it is not known whether behavioral and biological risks are simply risks for HPV infection itself.

OBJECTIVE

To prospectively examine risks of incident HPV infection in HPV-negative females and of incident LSIL development in females with HPV infection.

DESIGN

Prospective cohort study conducted between 1990-2000, with a median follow-up of 50 months.

SETTING AND PARTICIPANTS

Females aged 13 to 21 years who attended 2 family planning clinics in the San Francisco bay area; 496 had prevalent HPV infection and 105 were HPV-negative.

MAIN OUTCOME MEASURE

Incident development of HPV infection and LSIL, analyzed by various demographic, behavioral, and clinical risk factors.

RESULTS

Fifty-four incident HPV infections occurred in the 105 females who were HPV-negative at study entry (median duration of follow-up for those who remained HPV-negative was 26 months). Multivariable analysis showed that risks of HPV included sexual behavior (relative hazard [RH], 10.10; 95% confidence interval [CI], 3.24-31.50 per new partner per month), history of herpes simplex virus (RH, 3.54; 95% CI, 1.37-9.10), and history of vulvar warts (RH, 2.73; 95% CI, 1.27-5.87). Current use of oral contraceptives had a significantly protective effect (RH, 0.49; 95% CI, 0.28-0.86). Among the 496 individuals who were HPV-positive at baseline or in follow-up, there were 109 incident cases of LSIL during the follow-up interval, with a median follow-up time of 60 months for those who never developed LSIL. Human papillomavirus infection was the most significant risk factor for development of LSIL. The multivariable model showed the following risks for LSIL: HPV infection for less than 1 year (RH, 7.40; 95% CI, 4.74-11.57); HPV infection for 1 to 2 years (RH, 10.27; 95% CI, 5.64-18.69); HPV infection for 2 to 3 years (RH, 6.11; 95% CI, 1.86-20.06); and daily cigarette smoking (RH, 1.67; 95% CI, 1.12-2.48).

CONCLUSION

Our results indicate distinct risks for HPV and LSIL. In addition, most women with HPV infection in our study did not develop LSIL within a median follow-up period of 60 months. These findings underscore the hypothesis that certain biological risks thought to be associated with LSIL are, in fact, risks for acquisition of HPV. Cigarette smoking was a risk specific to LSIL, supporting the role of tobacco in neoplastic development.

Effects of individualized breast cancer risk counseling: a randomized trial

BACKGROUND

Studies have shown that a majority of women with a family history of breast cancer have exaggerated perceptions of their own risk of this disease and experience excessive anxiety. In response to the need to communicate more accurate risk information to these women, specialized programs for breast cancer risk counseling have been initiated in medical centers across the United States.

PURPOSE

Our purpose was 1) to evaluate the impact of a standardized protocol for individualized breast cancer risk counseling on comprehension of personal risk among first-degree relatives of index breast cancer patients and 2) to identify women most and least likely to benefit from such counseling.

METHODS

This study is a prospective randomized trial comparing individualized breast cancer risk counseling to general health counseling (control). We studied 200 women aged 35 years and older who had a family history of breast cancer in a first-degree relative. Women with a personal history of cancer were excluded. Risk comprehension was assessed as the concordance between perceived "subjective" lifetime breast cancer risk and estimated "objective" lifetime risk.

RESULTS

The results of logistic regression analysis showed that women who received risk counseling were significantly more likely to improve their risk comprehension, compared with women in the control condition (odds ratio [OR] = 3.5; 95% confidence interval [CI] = 1.3-9.5; P = .01). However, in both groups, about two thirds of women continued to overestimate their lifetime risks substantially following counseling. Examination of subjects by treatment interaction effects indicated that risk counseling did not produce improved comprehension among the large proportion of women who had high levels of anxious preoccupation with breast cancer at base line (P = .02). In addition, white women were less likely to benefit than African-American women (OR = 0.34; 95% CI = 0.11-0.99; P = .05).

CONCLUSION

Efforts to counsel women about their breast cancer risks are not likely to be effective unless their breast cancer anxieties are also addressed.

IMPLICATIONS

Attention to the psychological aspects of breast cancer risk will be critical in the development of risk-counseling programs that incorporate testing for the recently cloned breast cancer susceptibility gene, BRCA1 (and BRCA2 when that gene has also been cloned).

An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise

This study was designed to determine the response of muscle protein to the bolus ingestion of a drink containing essential amino acids and carbohydrate after resistance exercise. Six subjects (3 men, 3 women) randomly consumed a treatment drink (6 g essential amino acids, 35 g sucrose) or a flavored placebo drink 1 h or 3 h after a bout of resistance exercise on two separate occasions. We used a three-compartment model for determination of leg muscle protein kinetics. The model involves the infusion of ring-(2)H(5)-phenylalanine, femoral arterial and venous blood sampling, and muscle biopsies. Phenylalanine net balance and muscle protein synthesis were significantly increased above the predrink and corresponding placebo value (P < 0.05) when the drink was taken 1 or 3 h after exercise but not when the placebo was ingested at 1 or 3 h. The response to the amino acid-carbohydrate drink produced similar anabolic responses at 1 and 3 h. Muscle protein breakdown did not change in response to the drink. We conclude that essential amino acids with carbohydrates stimulate muscle protein anabolism by increasing muscle protein synthesis when ingested 1 or 3 h after resistance exercise.

The danger of weight loss in the elderly

Aging is generally accompanied by weight loss made up of both fat mass and fat-free mass. As more people, including elderly, are overweight or obese, weight loss is recommended to improve health. Health risks are decreased in overweight children and adults by dieting and exercise, but the health benefits of weight loss in elderly, particularly by calorie restriction, are uncertain. Rapid unintentional weight loss in elderly is usually indicative of underlying disease and accelerates the muscle loss which normally occurs with aging. Intentional weight loss, even when excess fat mass is targeted also includes accelerated muscle loss which has been shown in older persons to correlate negatively with functional capacity for independent living. Sarcopenic obesity, the coexistence of diminished lean mass and increased fat mass, characterizes a population particularly at risk for functional impairment since both sarcopenia (relative deficiency of skeletal muscle mass and strength) and obesity have been shown to predict disability. However, indices of overweight and obesity such as body mass index (BMI) do not correlate as strongly with adverse health outcomes such as cardiovascular disease in elderly as compared to younger individuals. Further, weight loss and low BMI in older persons are associated with mortality in some studies. On the other hand, studies have shown improvement in risk factors after weight loss in overweight/obese elderly. The recent focus on pro-inflammatory factors related to adiposity suggest that fat loss could ameliorate some catabolic conditions of aging since some cytokines may directly impact muscle protein synthesis and breakdown. Simply decreasing weight may also ease mechanical burden on weak joints and muscle, thus improving mobility. However, until a strategy is proven whereby further loss of muscle mass can be prevented, weight loss by caloric restriction in individuals with sarcopenic obesity should likely be avoided.

Evidence of activity-dependent withdrawal of corticospinal projections during human development

OBJECTIVE

To characterize the development of ipsilateral corticospinal projections from birth and compare to 1) development of contralateral projections in the same subjects and 2) ipsilateral corticospinal projections in subjects with unilateral lesions of the corticospinal system acquired perinatally or in adulthood.

METHOD

Transcranial magnetic stimulation excited the motor cortex, and responses were recorded bilaterally in pectoralis major, biceps brachii, and the first dorsal interosseus muscles. Subjects studied included 9 neonates recruited at birth, studied longitudinally for 2 years; 85 healthy subjects aged from birth to adulthood; 10 subjects with hemiplegic cerebral palsy; and 8 with hemiplegia after stroke.

RESULTS

In neonates, ipsilateral responses had significantly shorter onsets than contralateral responses but similar thresholds and amplitudes. Thresholds within both pathways increased in the first 3 months. Differential development was present from 3 months so that by 18 months ipsilateral responses were significantly smaller and had significantly higher thresholds and longer onset latencies than contralateral responses. A similar pattern of smaller and later ipsilateral responses was observed after transcranial magnetic stimulation of the intact cortex in subjects with stroke. In contrast, subjects with hemiplegic cerebral palsy had ipsilateral responses with onsets, thresholds and amplitudes similar to those of contralateral responses. Significant branching of contralateral corticospinal axons from the intact motor cortex was excluded by cross-correlation analysis.

CONCLUSIONS

These data, together with previously published anatomic and radiologic studies, are consistent with activity-dependent corticospinal axonal withdrawal during development and maintenance of increased corticomotoneuronal projections from the intact hemisphere after unilateral perinatal lesions.

Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise

The present study was designed to determine whether consumption of an oral essential amino acid-carbohydrate supplement (EAC) before exercise results in a greater anabolic response than supplementation after resistance exercise. Six healthy human subjects participated in two trials in random order, PRE (EAC consumed immediately before exercise), and POST (EAC consumed immediately after exercise). A primed, continuous infusion of L-[ring-(2)H(5)]phenylalanine, femoral arteriovenous catheterization, and muscle biopsies from the vastus lateralis were used to determine phenylalanine concentrations, enrichments, and net uptake across the leg. Blood and muscle phenylalanine concentrations were increased by approximately 130% after drink consumption in both trials. Amino acid delivery to the leg was increased during exercise and remained elevated for the 2 h after exercise in both trials. Delivery of amino acids (amino acid concentration times blood flow) was significantly greater in PRE than in POST during the exercise bout and in the 1st h after exercise (P < 0.05). Total net phenylalanine uptake across the leg was greater (P = 0.0002) during PRE (209 +/- 42 mg) than during POST (81 +/- 19). Phenylalanine disappearance rate, an indicator of muscle protein synthesis from blood amino acids, increased after EAC consumption in both trials. These results indicate that the response of net muscle protein synthesis to consumption of an EAC solution immediately before resistance exercise is greater than that when the solution is consumed after exercise, primarily because of an increase in muscle protein synthesis as a result of increased delivery of amino acids to the leg.

The accessible surface area and stability of oligomeric proteins

Protein structures are stabilized by hydrophobic and van der Waals forces, and by hydrogen bonds. The relation between these thermodynamic quantities and the actual three-dimensional structure of proteins can not be calculated precisely. However, certain empirical relations have been discovered. Hydrophobic energy is gained by the reduction of surface in contact with water. For monomeric proteins, the area of the surface accessible to solvent, and of that buried in the interior, is a simple function of molecular weight. Proteins with different shapes and secondary structures, but of the same molecular weight, have the same accessible surface area. It has been argued that there is no similar relationship for large oligomeric proteins. In this paper we show that the surface areas of oligomeric proteins, and the areas of the surface buried within them, are directly related to relative molecular mass. Although oligomers of the same molecular weight bury the same amounts of surface, the proportions buried within and between subunits vary. This has important implications for the role of subunit interfaces in the stability and activity of oligomeric proteins.

Adverse effects of low dose amiodarone: a meta-analysis

OBJECTIVES

We sought to assess the odds of experiencing adverse effects with low dose amiodarone therapy compared with placebo.

BACKGROUND

An estimate of the likelihood of experiencing amiodarone-related adverse effects with exposure to low daily doses of the drug is lacking in the published reports, and little information is available on adverse effect event rates in control groups not receiving the drug.

METHODS

Data from four published trials involving 1,465 patients were included in a meta-analysis design. The criteria for inclusion were 1) double-blind, placebo-controlled design; 2) absence of a crossover design between patient groups; 3) mean follow-up of at least 12 months; 4) maintenance amiodarone dose < or = 400 mg/day; and 5) presence of an explicit description of adverse effects. Data were pooled after testing for homogeneity of treatment effects across trials, and summary odds ratios were calculated by the Peto-modified Mantel-Haenszel method for each adverse effect.

RESULTS

The mean amiodarone dose per day ranged from 152 to 330 mg; 738 patients were randomized to receive amiodarone and 727 placebo. Exposure to amiodarone in this dose range, for a minimal duration of 12 months, resulted in odds similar to those of placebo for hepatic and gastrointestinal adverse effects, but in significantly higher odds than those of placebo (p < 0.05) for experiencing thyroid (odds ratio [OR] 4.2, 95% confidence interval [CI] 2.0 to 8.7), neurologic (OR 2.0, 95% CI 1.1 to 3.7), skin (OR 2.5, 95% CI 1.1 to 6.2), ocular (OR 3.4, 95% CI 1.2 to 9.6) and bradycardic (OR 2.2, 95% CI 1.1 to 4.3) adverse effects. A trend toward increased odds of pulmonary toxicity was noted (OR 2.0, 95% CI 0.9 to 5.3), but this did not reach statistical significance (p = 0.07). The unadjusted total incidence of drug discontinuation was 22.9% in the amiodarone group and 15.4% in the placebo group. The odds of discontinuing the drug in the amiodarone group was approximately 1.5 times that of the placebo group (OR 1.52, 95% CI 1.2 to 1.9) (p = 0.003).

CONCLUSIONS

Compared with placebo, there is a higher likelihood of experiencing several amiodarone-related adverse effects with exposure to low daily doses of the drug. Thus, although low dose amiodarone may be well tolerated, it is not free of adverse effects.

The case for an ancestral genetic system involving simple analogues of the nucleotides

The idea that the first living systems on earth were based on self-replicating RNA molecules has recently become popular as a result of the discovery of ribozymes. However, there are several major problems associated with the prebiotic synthesis of ribonucleotides. In addition, there is the newly recognized problem of enantiomeric cross-inhibition, whereby template-directed polymerization involving one enantiomer of RNA is inhibited strongly by the presence of the other enantiomer. Here we propose that RNA was preceded in the evolution of life by a polymer constructed from flexible, acyclic, probably prochiral nucleotide analogues that were synthesized readily on the primitive earth. Several potentially prebiotic nucleotide analogues are considered in this context, and some of the consequences of this proposal are discussed.

A simple genetic basis for a complex psychological trait in laboratory mice

Psychological traits are commonly inferred from covariation in sets of behavioral measures that otherwise appear to have little in common. Emotionality in mice is such a trait, defined here by covariation in activity and defecation in a novel environment and emergence into the open arms of an elevated plus maze. Behavioral and quantitative trait analyses were conducted on four measures obtained from 879 mice from an F2 intercross. Three loci, on murine chromosomes 1, 12, and 15, were mapped that influence emotionality. This trait, inferred from studies of strain, sex, and individual differences in rodents, may be related to human susceptibility to anxiety or neuroticism.

Crystal structure of P22 tailspike protein: interdigitated subunits in a thermostable trimer

The tailspike protein (TSP) of Salmonella typhimurium phage P22 is a part of the apparatus by which the phage attaches to the bacterial host and hydrolyzes the O antigen. It has served as a model system for genetic and biochemical analysis of protein folding. The x-ray structure of a shortened TSP (residues 109 to 666) was determined to a 2.0 angstrom resolution. Each subunit of the homotrimer contains a large parallel beta helix. The interdigitation of the polypeptide chains at the carboxyl termini is important to protrimer formation in the folding pathway and to thermostability of the mature protein.

Mutations in mitochondrial cytochrome c oxidase genes segregate with late-onset Alzheimer disease

Mounting evidence suggests that defects in energy metabolism contribute to the pathogenesis of Alzheimer disease (AD). Cytochrome c oxidase (CO) is kinetically abnormal, and its activity is decreased in brain and peripheral tissue in late-onset AD. CO is encoded by both the mitochondrial and the nuclear genomes. Its catalytic centers, however, are encoded exclusively by two mitochondrial genes, CO1 and CO2 (encoding CO subunits I and II, respectively). We searched these genes, as well as other mitochondrial genes, for mutations that might alter CO activity and cosegregate with AD. In the present study, specific missense mutations in the mitochondrial CO1 and CO2 genes but not the CO3 gene were found to segregate at a higher frequency with AD compared with other neurodegenerative or metabolic diseases. These mutations appear together in the same mitochondrial DNA molecule and define a unique mutant mitochondrial genome. Asymptomatic offspring of AD mothers had higher levels of these mutations than offspring of AD fathers, suggesting that these mutations can be maternally inherited. Cell lines expressing these mutant mitochondrial DNA molecules exhibited a specific decrease in CO activity and increased production of reactive oxygen species. We suggest that specific point mutations in the CO1 and CO2 genes cause the CO defect in AD. A CO defect may represent a primary etiologic event, directly participating in a cascade of events that results in AD.

Excitation of the corticospinal tract by electromagnetic and electrical stimulation of the scalp in the macaque monkey

1. The responses evoked by non-invasive electromagnetic and surface anodal electrical stimulation of the scalp (scalp stimulation) have been studied in the monkey. Conventional recording and stimulating electrodes, placed in the corticospinal pathway in the hand area of the left motor cortex, left medullary pyramid and the right spinal dorsolateral funiculus (DLF), allowed comparison of the actions of non-invasive stimuli and conventional electrical stimulation. 2. Responses to electromagnetic stimulation (with the coil tangential to the skull) were studied in four anaesthetized monkeys. In each case short-latency descending volleys were recorded in the contralateral DLF at threshold. In two animals later responses were also seen at higher stimulus intensities. Both early and late responses were of corticospinal origin since they could be completely collided by appropriately timed stimulation of the pyramidal tract. The latency of the early response in the DLF indicated that it resulted from direct activation of corticospinal neurones: its latency was the same as the latency of the antidromic action potentials evoked in the motor cortex from the recording site in the DLF. 3. Scalp stimulation, which was also investigated in three of the monkeys, evoked short-latency volleys at threshold and at higher stimulus intensities these were followed by later waves. The short-latency volleys could be collided from the pyramid and, at threshold, had latencies compatible with direct activation of corticospinal neurones. The longer latency volleys were also identified as corticospinal in origin. 4. The latency of the early volley evoked by electromagnetic stimulation remained constant with increasing stimulus intensities. In contrast, with scalp stimulation above threshold the latency of the early volleys decreased considerably, indicating remote activation of the corticospinal pathway below the level of the motor cortex. In two monkeys both collision and latency data suggest activation of the corticospinal pathway as far caudal as the medulla. 5. The majority of fast corticospinal fibres could be excited by scalp stimulation with intensities of 20% of maximum stimulator output. Electromagnetic stimulation at maximum stimulator output elicited a volley of between 70 and 90% of the size of the maximal volley evoked from the pyramidal electrodes. 6. Electromagnetic stimulation was also investigated in one awake monkey during the performance of a precision grip task. Short-latency EMG responses were evoked in hand and forearm muscles. The onsets of these responses were approximately 0.8 ms longer than the responses evoked by electrical stimulation of the pyramid.(ABSTRACT TRUNCATED AT 400 WORDS)

Home-based multisystemic therapy as an alternative to the hospitalization of youths in psychiatric crisis: clinical outcomes

OBJECTIVE

The primary purpose of this study was to determine whether multisystemic therapy (MST), modified for use with youths presenting psychiatric emergencies, can serve as a clinically viable alternative to inpatient psychiatric hospitalization.

METHOD

One hundred sixteen children and adolescents approved for emergency psychiatric hospitalization were randomly assigned to home-based MST or inpatient hospitalization. Assessments examining symptomatology, antisocial behavior, self-esteem, family relations, peer relations, school attendance, and consumer satisfaction were conducted at 3 times: within 24 hours of recruitment into the project, shortly after the hospitalized youth was released from the hospital (1-2 weeks after recruitment), and at the completion of MST home-based services (average of 4 months postrecruitment).

RESULTS

MST was more effective than emergency hospitalization at decreasing youths' externalizing symptoms and improving their family functioning and school attendance. Hospitalization was more effective than MST at improving youths' self-esteem. Consumer satisfaction scores were higher in the MST condition.

CONCLUSIONS

The findings support the view that an intensive, well-specified, and empirically supported treatment model, with judicious access to placement, can effectively serve as a family- and community-based alternative to the emergency psychiatric hospitalization of children and adolescents.

Neural processes involved in directing attention

Neural processes associated with two aspects of visual-spatial attention were investigated with event-related potential (ERPs): those that direct spatial attention to a given point in space and those that modulate the processing of sensory input after attention has been directed. The subjects were 6- to 9-year-old children (51 boys and 35 girls). An arrow cue directed attention from the central to peripheral visual field; targets were then flashed in the attended or ignored visual field 600 msec after the cue. The directing of attention to the left vs. right visual field was associated with hemispheric differences in slow potentials prior to the presentation of the targets. The earliest potential, which started about 200 msec after the cue and was negative over the hemisphere contralateral to the direction of attention, was greatest over the parietal area and appeared to reflect processes directing attention per se. The last potential, which peaked 60 msec after the target and was positive over the hemisphere contralateral to the direction of attention, was greatest over the occipital-parietal region. It appeared to reflect the modulation of cortical excitability in the regions receiving input from the relevant and irrelevant visual fields. The effects of spatial attention on P1, N1, and P3 ERP components following the targets replicated previous results. Boys appeared more aroused (as indicated by CNVs) and reflected faster and greater selective processing (as indicated by reaction time, and N1-P1 latency and amplitude) than girls.

Pharmacological effects of Lu AA21004: a novel multimodal compound for the treatment of major depressive disorder

1-[2-(2,4-Dimethylphenyl-sulfanyl)-phenyl]-piperazine (Lu AA21004) is a human (h) serotonin (5-HT)(3A) receptor antagonist (K(i) = 3.7 nM), h5-HT(7) receptor antagonist (K(i) = 19 nM), h5-HT(1B) receptor partial agonist (K(i) = 33 nM), h5-HT(1A) receptor agonist (K(i) = 15 nM), and a human 5-HT transporter (SERT) inhibitor (K(i) = 1.6 nM) (J Med Chem 54:3206-3221, 2011). Here, we confirm that Lu AA21004 is a partial h5-HT(1B) receptor agonist [EC(50) = 460 nM, intrinsic activity = 22%] using a whole-cell cAMP-based assay and demonstrate that Lu AA21004 is a rat (r) 5-HT(7) receptor antagonist (K(i) = 200 nM and IC(50) = 2080 nM). In vivo, Lu AA21004 occupies the r5-HT(1B) receptor and rSERT (ED(50) = 3.2 and 0.4 mg/kg, respectively) after subcutaneous administration and is a 5-HT(3) receptor antagonist in the Bezold-Jarisch reflex assay (ED(50) = 0.11 mg/kg s.c.). In rat microdialysis experiments, Lu AA21004 (2.5-10.0 mg/kg s.c.) increased extracellular 5-HT, dopamine, and noradrenaline in the medial prefrontal cortex and ventral hippocampus. Lu AA21004 (5 mg/kg per day for 3 days; minipump subcutaneously), corresponding to 41% rSERT occupancy, significantly increased extracellular 5-HT in the ventral hippocampus. Furthermore, the 5-HT(3) receptor antagonist, ondansetron, potentiated the increase in extracellular levels of 5-HT induced by citalopram. Lu AA21004 has antidepressant- and anxiolytic-like effects in the rat forced swim (Flinders Sensitive Line) and social interaction and conditioned fear tests (minimal effective doses: 7.8, 2.0, and 3.9 mg/kg). In conclusion, Lu AA21004 mediates its pharmacological effects via two pharmacological modalities: SERT inhibition and 5-HT receptor modulation. In vivo, this results in enhanced release of several neurotransmitters and antidepressant- and anxiolytic-like profiles at doses for which targets in addition to the SERT are occupied. The multimodal activity profile of Lu AA21004 is distinct from that of current antidepressants.

East pacific rise: hot springs and geophysical experiments

Hydrothermal vents jetting out water at 380 degrees +/- 30 degrees C have been discovered on the axis of the East Pacific Rise. The hottest waters issue from mineralized chimneys and are blackened by sulfide precipitates. These hydrothermal springs are the sites of actively forming massive sulfide mineral deposits. Cooler springs are clear to milky and support exotic benthic communities of giant tube worms, clams, and crabs similar to those found at the Galápagos spreading center. Four prototype geophysical experiments were successfully conducted in and near the vent area: seismic refraction measurements with both source (thumper) and receivers on the sea floor, on-bottom gravity measurements, in situ magnetic gradiometer measurements from the submersible Alvin over a sea-floor magnetic reversal boundary, and an active electrical sounding experiment. These high-resolution determinations of crustal properties along the spreading center were made to gain knowledge of the source of new oceanic crust and marine magnetic anomalies, the nature of the axial magma chamber, and the depth of hydrothermal circulation.