Persistent negative symptoms represent an alternative approach for assessing negative symptoms in the context of clinical trials. Persistent negative symptoms are designed to capture those symptoms ...that lead to functional impairment but are currently understudied and for which there are no currently available effective treatments. Persistent negative symptoms differ from the 2 most commonly used approaches: primary, enduring negative symptoms or deficit symptoms and negative symptoms broadly defined to include negative symptoms, regardless of their etiology or duration. In contrast to deficit symptoms, persistent negative symptoms may include secondary negative symptoms. However, in contrast to negative symptoms broadly defined, the secondary negative symptoms included in the assessment of persistent negative symptoms only include those that have failed to respond to usual treatments for secondary negative symptoms. In consequence, the presence of persistent negative symptoms identifies a patient population with clinically relevant symptomatology, which is larger than the one with the deficit syndrome but less heterogeneous than that captured through the use of a nonrestrictive definition of negative symptoms. This may facilitate the selection of subjects for inclusion into research and efforts to develop new pharmacological treatments and enhance our understanding of a relevant clinical problem. Ultimately, the investigation of the different entities characterized by negative symptoms, such as persistent negative symptoms, and the enhanced understanding of their biological and clinical characteristics may help to unravel the psychopathological and biological heterogeneity of schizophrenia.
Although high-risk mutations in identified major susceptibility genes (DNA mismatch repair genes and
) account for some familial aggregation of colorectal cancer, their population prevalence and the ...causes of the remaining familial aggregation are not known.
We studied the families of 5,744 colorectal cancer cases (probands) recruited from population cancer registries in the United States, Canada, and Australia and screened probands for mutations in mismatch repair genes and
We conducted modified segregation analyses using the cancer history of first-degree relatives, conditional on the proband's age at diagnosis. We estimated the prevalence of mutations in the identified genes, the prevalence of HR for unidentified major gene mutations, and the variance of the residual polygenic component.
We estimated that 1 in 279 of the population carry mutations in mismatch repair genes (
= 1 in 1,946,
= 1 in 2,841,
= 1 in 758,
= 1 in 714), 1 in 45 carry mutations in
, and 1 in 504 carry mutations associated with an average 31-fold increased risk of colorectal cancer in unidentified major genes. The estimated polygenic variance was reduced by 30% to 50% after allowing for unidentified major genes and decreased from 3.3 for age <40 years to 0.5 for age ≥70 years (equivalent to sibling relative risks of 5.1 to 1.3, respectively).
Unidentified major genes might explain one third to one half of the missing heritability of colorectal cancer.
Our findings could aid gene discovery and development of better colorectal cancer risk prediction models.
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The Schizophrenia Patient Outcomes Research Team (PORT) project has played a significant role in the development and dissemination of evidence-based practices for schizophrenia. In contrast to other ...clinical guidelines, the Schizophrenia PORT Treatment Recommendations, initially published in 1998 and first revised in 2003, are based primarily on empirical data. Over the last 5 years, research on psychopharmacologic and psychosocial treatments for schizophrenia has continued to evolve, warranting an update of the PORT recommendations. In consultation with expert advisors, 2 Evidence Review Groups (ERGs) identified 41 treatment areas for review and conducted electronic literature searches to identify all clinical studies published since the last PORT literature review. The ERGs also reviewed studies preceding 2002 in areas not covered by previous PORT reviews, including smoking cessation, substance abuse, and weight loss. The ERGs reviewed over 600 studies and synthesized the research evidence, producing recommendations for those treatments for which the evidence was sufficiently strong to merit recommendation status. For those treatments lacking empirical support, the ERGs produced parallel summary statements. An Expert Panel consisting of 39 schizophrenia researchers, clinicians, and consumers attended a conference in November 2008 in which consensus was reached on the state of the evidence for each of the treatment areas reviewed. The methods and outcomes of the update process are presented here and resulted in recommendations for 16 psychopharmacologic and 8 psychosocial treatments for schizophrenia. Another 13 psychopharmacologic and 4 psychosocial treatments had insufficient evidence to support a recommendation, representing significant unmet needs in important treatment domains.
In light of the large number of studies published since the 2004 update of Schizophrenia Patient Outcomes Research Team psychopharmacological treatment recommendations, we conducted an extensive ...literature review to determine whether the current psychopharmacological treatment recommendations required revision and whether there was sufficient evidence to warrant new treatment recommendations for prespecified outcomes of interest. We reviewed over 400 articles, which resulted in 16 treatment recommendations: the revision of 11 previous treatment recommendations and 5 new treatment recommendations. Three previous treatment recommendations were eliminated. There were 13 interventions and/or outcomes for which there was insufficient evidence for a treatment recommendation, and a statement was written to summarize the current level of evidence and identify important gaps in our knowledge that need to be addressed. In general, there was considerable consensus among the Psychopharmacology Evidence Review Group and the expert consultants. Two major areas of contention concerned whether there was sufficient evidence to recommend specific dosage ranges for the acute and maintenance treatment of first-episode and multi-episode schizophrenia and to endorse the practice of switching antipsychotics for the treatment of antipsychotic-related weight gain. Finally, there continue to be major gaps in our knowledge, including limited information on (1) the use of adjunctive pharmacological agents for the treatment of persistent positive symptoms or other symptom domains of psychopathology, including anxiety, cognitive impairments, depressive symptoms, and persistent negative symptoms and (2) the treatment of co-occurring substance or medical disorders that occur frequently in individuals with schizophrenia.
Impairments in willingness to exert effort contribute to the motivational deficits characteristic of the negative symptoms of schizophrenia. The current study evaluated the psychometric properties of ...5 new or adapted paradigms to determine their suitability for use in clinical trials of schizophrenia. This study included 94 clinically stable participants with schizophrenia and 40 healthy controls. The effort-based decision-making battery was administered twice to the schizophrenia group (baseline, 4-week retest) and once to the control group. The 5 paradigms included 1 that assesses cognitive effort, 1 perceptual effort, and 3 that assess physical effort. Each paradigm was evaluated on (1) patient vs healthy control group differences, (2) test-retest reliability, (3) utility as a repeated measure (ie, practice effects), and (4) tolerability. The 5 paradigms showed varying psychometric strengths and weaknesses. The Effort Expenditure for Rewards Task showed the best reliability and utility as a repeated measure, while the Grip Effort Task had significant patient-control group differences, and superior tolerability and administration duration. The other paradigms showed weaker psychometric characteristics in their current forms. These findings highlight challenges in adapting effort and motivation paradigms for use in clinical trials.
Neisseria are obligate human pathogens causing bacterial meningitis, septicaemia and gonorrhoea. Neisseria require iron for survival and can extract it directly from human transferrin for transport ...across the outer membrane. The transport system consists of TbpA, an integral outer membrane protein, and TbpB, a co-receptor attached to the cell surface; both proteins are potentially important vaccine and therapeutic targets. Two key questions driving Neisseria research are how human transferrin is specifically targeted, and how the bacteria liberate iron from transferrin at neutral pH. To address these questions, we solved crystal structures of the TbpA-transferrin complex and of the corresponding co-receptor TbpB. We characterized the TbpB-transferrin complex by small-angle X-ray scattering and the TbpA-TbpB-transferrin complex by electron microscopy. Our studies provide a rational basis for the specificity of TbpA for human transferrin, show how TbpA promotes iron release from transferrin, and elucidate how TbpB facilitates this process.
Effort-based decision making has strong conceptual links to the motivational disturbances that define a key subdomain of negative symptoms. However, the extent to which effort-based decision-making ...performance relates to negative symptoms, and other clinical and functionally important variables has yet to be systematically investigated. In 94 clinically stable outpatients with schizophrenia, we examined the external validity of 5 effort-based paradigms, including the Effort Expenditure for Rewards, Balloon Effort, Grip Strength Effort, Deck Choice Effort, and Perceptual Effort tasks. These tasks covered 3 types of effort: physical, cognitive, and perceptual. Correlations between effort related performance and 6 classes of variables were examined, including: (1) negative symptoms, (2) clinically rated motivation and community role functioning, (3) self-reported motivational traits, (4) neurocognition, (5) other psychiatric symptoms and clinical/demographic characteristics, and (6) subjective valuation of monetary rewards. Effort paradigms showed small to medium relationships to clinical ratings of negative symptoms, motivation, and functioning, with the pattern more consistent for some measures than others. They also showed small to medium relations with neurocognitive functioning, but were generally unrelated to other psychiatric symptoms, self-reported traits, antipsychotic medications, side effects, and subjective valuation of money. There were relatively strong interrelationships among the effort measures. In conjunction with findings from a companion psychometric article, all the paradigms warrant further consideration and development, and 2 show the strongest potential for clinical trial use at this juncture.
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