On the Rationality of Decision-Making Studies: Part 1: Decision Models of Treatment Choice

With reference to both critiques and empirical studies, the theoretical and methodological grounding of anthropological research on medical decision making is examined in this article, giving particular attention to the construction and evaluation of cognitively oriented decision models. A decisionmodeling study carried out in the Mexican village of Pichátaro (in conjunction with James C. Young) frames an exploration of some of the tensions and points of contention about the aims and designs of cognitively oriented studies of decision modeling. While a decision model can provide a reasonably good guide to an understanding of treatment actions and the culturally based rationality that underlies them, such models fall short when they are oriented primarily around predicting treatment accounts. They should also attend to the jointly cultural, personal, social, and cognitive constructive processes through which meaning is conferred upon the occurrence of illness, [care seeking, decision models, decision making, Mexico]     

Applying Signaling Theory to Traditional Cultural Rituals

The branch of evolutionary theory known as signaling theory attempts to explain various forms of communication. Social scientists have explained many traditional rituals as forms of communication that promote cooperative social relationships among participants. Both evolutionists and social scientists have realized the importance of trust for the formation and maintenance of cooperative social relationships. These factors have led to attempts to apply signaling theory to traditional cultural rituals in various ways. This paper uses the traditional ritual of mumming in small Newfoundland fishing villages to evaluate alternative hypotheses about the connection between rituals, communication, trust, and cooperation. Mumming is found to be most consistent with the hypothesis that it is a ritual of trust wherein participants take a specific type of risk: the risk of harm at the hands of other participants. Individuals who take this risk actively signal their trust. Conversely, individuals who restrain themselves from inflicting harm on other participants actively signal their trustworthiness.

Applying of Hierarchical Clustering to Analysis of Protein Patterns in the Human Cancer-Associated Liver

Background

There are two ways that statistical methods can learn from biomedical data. One way is to learn classifiers to identify diseases and to predict outcomes using the training dataset with established diagnosis for each sample. When the training dataset is not available the task can be to mine for presence of meaningful groups (clusters) of samples and to explore underlying data structure (unsupervised learning).

Results

We investigated the proteomic profiles of the cytosolic fraction of human liver samples using two-dimensional electrophoresis (2DE). Samples were resected upon surgical treatment of hepatic metastases in colorectal cancer. Unsupervised hierarchical clustering of 2DE gel images (n = 18) revealed a pair of clusters, containing 11 and 7 samples. Previously we used the same specimens to measure biochemical profiles based on cytochrome P450-dependent enzymatic activities and also found that samples were clearly divided into two well-separated groups by cluster analysis. It turned out that groups by enzyme activity almost perfectly match to the groups identified from proteomic data. Of the 271 reproducible spots on our 2DE gels, we selected 15 to distinguish the human liver cytosolic clusters. Using MALDI-TOF peptide mass fingerprinting, we identified 12 proteins for the selected spots, including known cancer-associated species.

Conclusions/Significance

Our results highlight the importance of hierarchical cluster analysis of proteomic data, and showed concordance between results of biochemical and proteomic approaches. Grouping of the human liver samples and/or patients into differing clusters may provide insights into possible molecular mechanism of drug metabolism and creates a rationale for personalized treatment.     

Defining Disease Heterogeneity to Guide the Empirical Treatment of Febrile Illness in Resource Poor Settings

Background

Malaria incidence is in decline in many parts of SE Asia leading to a decreasing proportion of febrile illness that is attributable to malaria. However in the absence of rapid, affordable and accurate diagnostic tests, the non-malaria causes of these illnesses cannot be reliably identified. Studies on the aetiology of febrile illness have indicated that the causes are likely to vary by geographical location within countries (i.e. be spatially heterogeneous) and that national empirical treatment policies based on the aetiology measured in a single location could lead to inappropriate treatment.

Methods

Using data from Vientiane as a reference for the incidence of major febrile illnesses in the Lao People''s Democratic Republic (Laos) and estimated incidences, plausible incidence in other Lao provinces were generated using a mathematical model for a range of national and local scale variations. For a range of treatment protocols, the mean number of appropriate treatments was predicted and the potential impact of a spatially explicit national empirical treatment protocol assessed.

Findings

The model predicted a negative correlation between number of appropriate treatments and the level of spatial heterogeneity. A spatially explicit national treatment protocol was predicted to increase the number of appropriate treatments by 50% for intermediate levels of spatial heterogeneity.

Conclusions

The results suggest that given even only moderate spatial variation, a spatially explicit treatment algorithm will result in a significant improvement in the outcome of undifferentiated fevers in Laos and other similar resource poor settings.     

When to Ignore Advice: Invasion Predictions and Decision Theory

Organisms generally become pests at a low rate. As a consequence of this low base-rate probability, the large majority of organisms rejected in any random sample of potential introductions would probably be harmless, despite the fairly high accuracy of some recently proposed risk assessment systems for exotic introductions. Here we distinguish between a system's accuracy (the proportion of a group of known pest species that would be correctly identified as pests) and reliability (the rate of false positives and false negatives produced once the base-rate is taken into account). We next adapt a decision theory analysis of earthquake prediction to explore when we would be best advised to ignore the recommendations of a screening system for exotic introductions. In one scenario, we show that a pest risk assessment system with an accuracy of 85% would be better ignored, unless the damage caused by introducing a pest is eight times or more that caused by not introducing a harmless organism that is potentially useful. Furthermore, because of the base-rate effect, in certain situations it may be more efficient to focus on identifying potential invaders from amongst already naturalized species than from amongst species at the importation stage.     

Resampling Method for Applying Density-Dependent Habitat Selection Theory to Wildlife Surveys

Isodar theory can be used to evaluate fitness consequences of density-dependent habitat selection by animals. A typical habitat isodar is a regression curve plotting competitor densities in two adjacent habitats when individual fitness is equal. Despite the increasing use of habitat isodars, their application remains largely limited to areas composed of pairs of adjacent habitats that are defined a priori. We developed a resampling method that uses data from wildlife surveys to build isodars in heterogeneous landscapes without having to predefine habitat types. The method consists in randomly placing blocks over the survey area and dividing those blocks in two adjacent sub-blocks of the same size. Animal abundance is then estimated within the two sub-blocks. This process is done 100 times. Different functional forms of isodars can be investigated by relating animal abundance and differences in habitat features between sub-blocks. We applied this method to abundance data of raccoons and striped skunks, two of the main hosts of rabies virus in North America. Habitat selection by raccoons and striped skunks depended on both conspecific abundance and the difference in landscape composition and structure between sub-blocks. When conspecific abundance was low, raccoons and striped skunks favored areas with relatively high proportions of forests and anthropogenic features, respectively. Under high conspecific abundance, however, both species preferred areas with rather large corn-forest edge densities and corn field proportions. Based on random sampling techniques, we provide a robust method that is applicable to a broad range of species, including medium- to large-sized mammals with high mobility. The method is sufficiently flexible to incorporate multiple environmental covariates that can reflect key requirements of the focal species. We thus illustrate how isodar theory can be used with wildlife surveys to assess density-dependent habitat selection over large geographic extents.     

The Narrative Challenge to Cognitive Behavioral Treatment of Sexual Offenders

Imprisoned sexual offenders undergoing treatment are expected to deduce and follow a treatment schema constructed on the foundations of cognitive behavioral therapy (CBT). A key element of their treatment program is the presentation of a core narrative, their autobiography, to treatment staff and peers. Examining this form of prison-based treatment through the lens of narrative theory, I argue that the autobiographies and other stories that are developed and performed as part of this treatment process are largely the product of the imposition of this treatment schema in combination with dynamic group processes. Ironically, the treatment schema and the prevailing dynamics work to subvert the fundamental forensic goal of having inmates disclose aspects of their lives and crimes as an essential stepping stone toward rehabilitation. The narratives that emerge, both in detail and in meaning, cannot be seen as simply reflections of any single individual's life but, instead, as composites built on, and reflective of, cultural processes somewhat unique to the forensic context. Narrative, a fundamental mode of thinking and communication, necessarily challenges the directed nature of autobiographical presentation derived from CBT. In such circumstances, the effectiveness of CBT for sexual offenders is questionable.     

Decision Theory and the Concept of Threshold in Psychophysics

Psychophysics deals basically with how signals are perceived. It is assumed that a signal or stimulus is perceived after it reaches a certain threshold value, called the sensory threshold. Thus, there are two possible states: either a signal is perceived by the neuronal system, or it is not. Fechner deserves most of the credit for the concept of the sensory threshold and for detailing the various techniques for measuring it. A discussion of this cardinal concept may be found in his book Elemente der Psychophysik (1860), although the idea is actually of much earlier origins: Leibnitz and Herbart certainly spoke of it, and indeed it seems to have been considered even by ancient Greek philosophers. Methods for measuring the sensory threshold were known even before Fechner; his contribution was being the first to systematize and perfect them. It is for this reason that his book (Elemente) is considered basic.     

On the Application of Fuzzy Decision Theory in Chemotherapy

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How to Rethink Evolutionary Theory: A Plurality of Evolutionary Patterns

Nature has recently depicted the empirical advancements of the theory of evolution as a confrontation between “reformists”, that claim for an urgent rethinking of the standard neo-Darwinian approach including so far neglected factors and processes, and “conservatives” who reply “all is well” about the current evolutionary research programme based on genetic variation and natural selection. The fight is mainly around genetic reductionism, but it seems inconclusive. Reformists stress very important factors, but they are still missing a coherent proposal about the architecture of the future extended evolutionary theory. Conservative react defensively, relying just on non-essential add-ons to the old and stable neo-Darwinian core. We analyze the debate and we propose an interpretation. Evolutionary biology is a rapidly expanding field. The bone of contention is how to update and extend the central core of the Darwinian legacy. We propose here the idea that what is happening in the field today is a development of the evolutionary research programme, whose structure is composed of a set of compatible and integrated evolutionary patterns. Evolutionary biology has been extended over its history by the inclusion of more and more patterns, rather than by revision to core theory. Niles Eldredge’s “Hierarchy Theory” is an example of global structure (meta-theory) aiming at incorporating and unifying the currently observed evolutionary patterns.     

A Strategy to Calculate the Patterns of Nutrient Consumption by Microorganisms Applying a Two-Level Optimisation Principle to Reconstructed Metabolic Networks

Bacterial responses to environmental changes rely on a complex network of biochemical reactions. The properties of the metabolic network determining these responses can be divided into two groups: the stoichiometric properties, given by the stoichiometry matrix, and the kinetic/thermodynamic properties, given by the rate equations of the reaction steps. The stoichiometry matrix represents the maximal metabolic capabilities of the organism, and the regulatory mechanisms based on the rate laws could be considered as being responsible for the administration of these capabilities. Post-genomic reconstruction of metabolic networks provides us with the stoichiometry matrix of particular strains of microorganisms, but the kinetic aspects of in vivo rate laws are still largely unknown. Therefore, the validity of predictions of cellular responses requiring detailed knowledge of the rate equations is difficult to assert. In this paper, we show that by applying optimisation criteria to the core stoichiometric network of the metabolism of Escherichia coli, and including information about reversibility/irreversibility only of the reaction steps, it is possible to calculate bacterial responses to growth media with different amounts of glucose and galactose. The target was the minimisation of the number of active reactions (subject to attaining a growth rate higher than a lower limit) and subsequent maximisation of the growth rate (subject to the number of active reactions being equal to the minimum previously calculated). Using this two-level target, we were able to obtain by calculation four fundamental behaviours found experimentally: inhibition of respiration at high glucose concentrations in aerobic conditions, turning on of respiration when glucose decreases, induction of galactose utilisation when the system is depleted of glucose and simultaneous use of glucose and galactose as carbon sources when both sugars are present in low concentrations. Preliminary results of the coarse pattern of sugar utilisation were also obtained with a genome-scale E. coli reconstructed network, yielding similar qualitative results.     

RAPD技术用于昆虫离体细胞鉴定的初步探讨

探讨利用RAPD技术对昆虫离体培养进行快速鉴定的可能性。实验中所选用的细胞材料是美国棉铃虫(Heliothis Zea)细胞株Hz-AM3(简称Hz)、粉纹夜蛾(Trichoplusiani)细胞株BIT-TN5B1-4(简称5B1)、斜纹夜蛾(Spodoptera litura)卵巢细胞株SL1,利用RAPD技术找出三种细胞的差异条带,从而证明RAPD技术在昆虫离体细胞的快速鉴定中很有前景。     

山莨胆碱在慢性乙型肝炎治疗中的应用研究

山莨菪碱(654-2)是我国首先从茄科植物唐古特山莨菪中提取的一种生物碱,分子式C_(17)H_(23)NO_4;具有受体阻滞和钙通道拮抗作用,在临床中应用于多学科疾病的治疗和抢救。近年来,山莨菪碱对肝损伤的保护作用的基础研究得到证实,临床应用也取得一定认识,特别是在对慢型乙型肝炎的治疗作用方面。现就山莨菪碱对慢型乙型肝炎在肝细胞保护及抗肝纤维化方面的作用机制、临床应用作一综述。