Using explainable artificial intelligence to identify linguistic biomarkers of amyloid pathology in primary progressive aphasia

Introduction

Recent success has been achieved in Alzheimer's disease (AD) clinical trials targeting amyloid beta (β), demonstrating a reduction in the rate of cognitive decline. However, testing methods for amyloid-β positivity are currently costly or invasive, motivating the development of accessible screening approaches to steer patients toward appropriate diagnostic tests. Here, we employ a pre-trained language model (Distil-RoBERTa) to identify amyloid-β positivity from a short, connected speech sample. We further use explainable AI (XAI) methods to extract interpretable linguistic features that can be employed in clinical practice.

Methods

We obtained language samples from 74 patients with primary progressive aphasia (PPA) across its three variants. Amyloid-β positivity was established through the analysis of cerebrospinal fluid, amyloid PET, or autopsy. 51% of the sample was amyloid-positive. We trained Distil-RoBERTa for 16 epochs with a batch size of 6 and a learning rate of 5e-5, and used the LIME algorithm to train interpretation models to interpret the trained classifier's inference conditions.

Results

Over ten runs of 10-fold cross-validation, the classifier achieved a mean accuracy of 92%, SD = 0.01. Interpretation models were able to capture the classifier's behavior well, achieving an accuracy of 97% against classifier predictions, and uncovering several novel speech patterns that may characterize amyloid-β positivity.

Discussion

Our work improves previous research which indicates connected speech is a useful diagnostic input for prediction of the presence of amyloid-β in patients with PPA. Further, we leverage XAI techniques to reveal novel linguistic features that can be tested in clinical practice in the appropriate subspecialty setting. Computational linguistic analysis of connected speech shows great promise as a novel assessment method in patients with AD and related disorders.

Accelerating Medicines Partnership® Schizophrenia (AMP® SCZ): Rationale and Study Design of the Largest Global Prospective Cohort Study of Clinical High Risk for Psychosis

This article describes the rationale, aims, and methodology of the Accelerating Medicines Partnership® Schizophrenia (AMP® SCZ). This is the largest international collaboration to date that will develop algorithms to predict trajectories and outcomes of individuals at clinical high risk (CHR) for psychosis and to advance the development and use of novel pharmacological interventions for CHR individuals. We present a description of the participating research networks and the data processing analysis and coordination center, their processes for data harmonization across 43 sites from 13 participating countries (recruitment across North America, Australia, Europe, Asia, and South America), data flow and quality assessment processes, data analyses, and the transfer of data to the National Institute of Mental Health (NIMH) Data Archive (NDA) for use by the research community. In an expected sample of approximately 2000 CHR individuals and 640 matched healthy controls, AMP SCZ will collect clinical, environmental, and cognitive data along with multimodal biomarkers, including neuroimaging, electrophysiology, fluid biospecimens, speech and facial expression samples, novel measures derived from digital health technologies including smartphone-based daily surveys, and passive sensing as well as actigraphy. The study will investigate a range of clinical outcomes over a 2-year period, including transition to psychosis, remission or persistence of CHR status, attenuated positive symptoms, persistent negative symptoms, mood and anxiety symptoms, and psychosocial functioning. The global reach of AMP SCZ and its harmonized innovative methods promise to catalyze the development of new treatments to address critical unmet clinical and public health needs in CHR individuals.

Using Generative Artificial Intelligence to Classify Primary Progressive Aphasia from Connected Speech

Neurodegenerative dementia syndromes, such as Primary Progressive Aphasias (PPA), have traditionally been diagnosed based in part on verbal and nonverbal cognitive profiles. Debate continues about whether PPA is best subdivided into three variants and also regarding the most distinctive linguistic features for classifying PPA variants. In this study, we harnessed the capabilities of artificial intelligence (AI) and natural language processing (NLP) to first perform unsupervised classification of concise, connected speech samples from 78 PPA patients. Large Language Models discerned three distinct PPA clusters, with 88.5% agreement with independent clinical diagnoses. Patterns of cortical atrophy of three data-driven clusters corresponded to the localization in the clinical diagnostic criteria. We then used NLP to identify linguistic features that best dissociate the three PPA variants. Seventeen features emerged as most valuable for this purpose, including the observation that separating verbs into high and low-frequency types significantly improves classification accuracy. Using these linguistic features derived from the analysis of brief connected speech samples, we developed a classifier that achieved 97.9% accuracy in predicting PPA subtypes and healthy controls. Our findings provide pivotal insights for refining early-stage dementia diagnosis, deepening our understanding of the characteristics of these neurodegenerative phenotypes and the neurobiology of language processing, and enhancing diagnostic evaluation accuracy.

Natural language processing in psychiatry: the promises and perils of a transformative approach

A person's everyday language can indicate patterns of thought and emotion predictive of mental illness. Here, we discuss how natural language processing methods can be used to extract indicators of mental health from language to help address long-standing problems in psychiatry, along with the potential hazards of this new technology.

P–037 Influence of sperm selection by microfluidic device on outcomes of in vitro fertilization cycles

Study question

Does sperm selection by a microfluidic sperm-sorting device improve laboratory outcomes of intracytoplasmic sperm injection cycles?

Summary answer

The ZyMōtTMdevice seems a good alternative to the conventional swim-up technique, possibly increasing progressive sperm motility post processing and blastulation rate.

What is known already

It is well-known that high levels of sperm DNA fragmentation negatively impact not only early embryonic development but also embryo genome activation. Microfluidic technologies for processing sperm samples selection such as the ZyMōtTM device have been developed to sort sperm with lower rates of sperm DNA fragmentation in order to improve in vitro fertilization (IVF) outcomes. Moreover, it offers several advantages: working with very small volume samples, high sensitivity and low reaction times, automatic sample treatment and analysis, among others. However, the real benefits on the clinical and laboratory outcomes of IVF cycles is yet to be determined.

Study design, size, duration

We performed a retrospective study including 126 seminal samples processed between May 2019 and December 2020. These samples belong to 63 infertile couples that underwent 2 consecutive IVF cycles using the swim-up technique in the first cycle (n = 63) and the ZyMōtTM device in the second (n = 63). The oocytes of the female partners were recovered and inseminated, and the embryonic culture was carried out until the blastocyst stage, when the quality of these embryos was analyzed. Participants/materials, setting, methods: A total of 118 seminal samples from 59 couples were included. Four couples were excluded due to insufficient seminal volume / concentration (2) or absence of mature oocytes recovered (2). Laboratory outcomes were evaluated including semen parameters post processing, as well as fertilization, cleavage, blastulation (blastocyst among cleavage stage) and top-quality blastocyst rates. Continuous variables were analyzed by paired Student’s t-test or Wilcoxon signed-rank test, as appropriate. Differences were considered significant when p-value < 0.05.

Main results and the role of chance

We did not find any difference in the percentage of non-progressive sperm motility [0 (0–33%) vs. 0 (0–10%); p = 0.063] and immotile sperm [0 (0–70%) vs. 0 (0–80%); p = 0.095] post processing when comparing the swim-up technique with the ZyMōtTM device. Likewise, no significant differences were detected regarding fertilization [83% (0–100%) vs. 89% (0–100%); p = 0.104] and cleavage [100% (0–100%) vs. 100% (80–100%); p = 0.217] rates in both groups. Nevertheless, there was a significant difference in the percentage of progressive sperm motility [100% (20–100%) vs. 100% (10–100%); p = 0.012] post processing, as well as blastulation [37% ± 0.32 vs. 50% ± 0.3; p = 0.031] and top-quality blastocyst [13.5% (0–100%) vs. 33% (0–100%); p = 0.009] rates, favoring the ZyMōtTM device.

Limitations, reasons for caution

The retrospective design and the small sample size make the study prone to bias. Furthermore, we do not have data on sperm DNA fragmentation pre and post processing. Clinical outcomes were not evaluated due to insufficient statistical power, since embryo transfer has not yet been accomplished in several patients.

Wider implications of the findings: Besides the ZyMōtTM device has been indicated as a new tool to potentially improve laboratory and clinical IVF outcomes, it offers the advantage of being safe, fast, easy-to-use and less influenced by human errors. Further well-designed prospective studies are needed to prove its cost-effectiveness.

Trial registration number

Not applicable

Language as a biomarker for psychosis: A natural language processing approach

Human ratings of conceptual disorganization, poverty of content, referential cohesion and illogical thinking have been shown to predict psychosis onset in prospective clinical high risk (CHR) cohort studies. The potential value of linguistic biomarkers has been significantly magnified, however, by recent advances in natural language processing (NLP) and machine learning (ML). Such methodologies allow for the rapid and objective measurement of language features, many of which are not easily recognized by human raters. Here we review the key findings on language production disturbance in psychosis. We also describe recent advances in the computational methods used to analyze language data, including methods for the automatic measurement of discourse coherence, syntactic complexity, poverty of content, referential coherence, and metaphorical language. Linguistic biomarkers of psychosis risk are now undergoing cross-validation, with attention to harmonization of methods. Future directions in extended CHR networks include studies of sources of variance, and combination with other promising biomarkers of psychosis risk, such as cognitive and sensory processing impairments likely to be related to language. Implications for the broader study of social communication, including reciprocal prosody, face expression and gesture, are discussed.

Atrial and atrioventricular resynchronization the benefit of bachmanns bundle and his bundle pacing

 

The current treatment of patients with heart failure and concomitant atrioventricular conduction delay is difficult. Recommendations indicate the possibility to use the classic resynchronization but in the presence of narrow QRS-complex such approach could be even harmful. Without a sufficient LBBB morphology as indication for classical CRT, those patients would lose their narrow QRS complex with negative consequences for the hearts functional status.

A new therapeutic option for those patients to re-establish the physiological atrioventricular mechanical sequence is the permanent His-bundle pacing (pHBP). Advantages like physiological activation sequence of the ventricular myocardium, less affected by AF compared to classical CRT and reversal of mitral regurgitation should be enumerated to show it's beneficial effect. Additionally the use of Bachmann's-bundle pacing can correct the prolonged interatrial conduction thus further contribute to the echocardiographic and clinical improvement.

The aim of the study is to assess the influence of Bachmann's-bundle pacing and His-bundle pacing on the reversed remodeling of the heart in patients with heart failure and atrioventricular block.

The study group included 21 patients (7 women and 14 men) undergoing cardiac resynchronization using Bachmann's-bundle pacing and permanent His-bundle pacing from LV channel for atrioventricular conduction delay. All the patients had narrow QRS-complex which prevented us to use classic resynchronization. 13 CRT-D and 8 CRT-P devices were implanted according to the ejection fraction and ventricular arrhythmia risk assessment. In all patients the direct His-bundle pacing was successfully achieved, selective in 17 and non-selective in 4 patients. The mean follow-up (FU) period was 8.8 months (1–26 months). The echocardiographic, clinical and ECG results are presented in the table 1.

Conclusions

1. The correction of atrioventricular and interatrial conduction delay resulting in improvement of atrioventricular mechanical coupling can contribute to the reversed remodeling of the heart.

2. This also improves the patient's functional status.

3. In some patients this approach could lead to the normalization of echocardiographic parameters of the left ventricle.

Funding Acknowledgement

Type of funding source: None

A machine learning approach to predicting psychosis using semantic density and latent content analysis

Subtle features in people’s everyday language may harbor the signs of future mental illness. Machine learning offers an approach for the rapid and accurate extraction of these signs. Here we investigate two potential linguistic indicators of psychosis in 40 participants of the North American Prodrome Longitudinal Study. We demonstrate how the linguistic marker of semantic density can be obtained using the mathematical method of vector unpacking, a technique that decomposes the meaning of a sentence into its core ideas. We also demonstrate how the latent semantic content of an individual’s speech can be extracted by contrasting it with the contents of conversations generated on social media, here 30,000 contributors to Reddit. The results revealed that conversion to psychosis is signaled by low semantic density and talk about voices and sounds. When combined, these two variables were able to predict the conversion with 93% accuracy in the training and 90% accuracy in the holdout datasets. The results point to a larger project in which automated analyses of language are used to forecast a broad range of mental disorders well in advance of their emergence.

Effect of oral administration of Tribulus terrestris extract on semen quality and body fat index of infertile men

Male fertility can be evaluated through complete semen analysis. Plants belonging to the Tribulus genus are known for their role in enhancing sex hormone levels and semen quality. The aim of this study was to evaluate the effects of T. terrestris on semen quality and physiological parameters. Sixty-five men with abnormal semen evaluation were included in this study, in which they were prescribed with oral administration of Androsten^® (250 mg of Tribulus terrestris dried extract per capsule). Body fat percentage, lean muscle mass gain, fluctuation in steroid hormone levels and all semen parameters were analysed during the period of treatment. The results demonstrated that decrease in the percentage of body fat and increase in lean mass were significant, as well as increase in dihydrotestosterone levels. Complete semen analysis evaluated at the end of treatment showed significant enhancement in sperm concentration, motility and liquefaction time. Protodioscin, the main phytochemical agent of the Tribulus genus, acts on sertoli cells, germ cell proliferation and growth of seminiferous tubules. This component is known to convert testosterone into dihydrotestosterone, which plays important roles in male attributes. Our results indicate the therapeutic use of Tribulus terrestris by men presenting altered semen parameters, and/or undergoing infertility treatment.

Causal reasoning with forces

Causal composition allows people to generate new causal relations by combining existing causal knowledge. We introduce a new computational model of such reasoning, the force theory, which holds that people compose causal relations by simulating the processes that join forces in the world, and compare this theory with the mental model theory (Khemlani et al., 2014) and the causal model theory (Sloman et al., 2009), which explain causal composition on the basis of mental models and structural equations, respectively. In one experiment, the force theory was uniquely able to account for people's ability to compose causal relationships from complex animations of real-world events. In three additional experiments, the force theory did as well as or better than the other two theories in explaining the causal compositions people generated from linguistically presented causal relations. Implications for causal learning and the hierarchical structure of causal knowledge are discussed.

Serum concentrations of polychlorinated biphenyls (PCBs) in participants of the Anniston Community Health Survey

Serum concentrations of 35 ortho-substituted polychlorinated biphenyl congeners (PCBs) were measured in 765 adults from Anniston, Alabama, where PCBs were manufactured between 1929 and 1971. As part of the Anniston Community Health Survey (ACHS), demographic data, questionnaire information, and blood samples were collected from participants in 2005-2007. Forty-six percent of study participants were African-American, 70% were female, and the median age was 56 years. The median concentration of the sum of 35 PCB congeners (ΣPCBs) was 528 ng/g lipid, with a 90th percentile of 2,600 ng/g lipid, minimum of 17.0 ng/g lipid, and maximum of 27,337 ng/g lipid. The least square geometric mean ΣPCBs was more than 2.5 times higher for African-American participants than for White participants (866 ng/g lipid vs. 331 ng/g lipid); this difference did not change materially after adjustment for age, sex, body mass index (BMI) and current smoking. In spite of large differences in absolute PCB levels, relative contributions of individual congeners to ΣPCBs were quite similar between race groups. Nevertheless, while percent contributions to ΣPCBs for most of the most abundant penta- to heptachlorobiphenyls were higher among African-Americans, the percentages were higher in Whites for the lower-chlorinated PCBs 28 and 74 and for octa- to decachlorinated PCBs. No major differences were observed in geometric mean ΣPCBs between women and men when adjusted for age, race, BMI and current smoking (516 ng/g lipid vs. 526 ng/g lipid). Principal component analysis revealed groups of co-varying congeners that appear to be determined by chlorine substitution patterns. These congener groupings were similar between ACHS participants and the National Health and Nutrition Examination Survey (NHANES) 2003-04 sample of the general United States population, despite ACHS participants having serum concentrations of ΣPCBs two to three times higher than those in comparable age and race groups from NHANES.

Spatial language and the psychological reality of schematization

Although the representations underlying spatial language are often assumed to be schematic in nature, empirical evidence for a schematic format of representation is lacking. In this research, we investigate the psychological reality of such a format, using simulated motion during scene processing--previously linked to schematization--as a diagnostic. One group of participants wrote a verbal description of a scene and then completed a change detection task assessing simulated motion, while another group completed only the latter task. We expected that effects of simulated motion would be stronger following language use than not, and specifically following the use of spatial, relative to non-spatial, language. Both predictions were supported. Further, the effect of language was scene independent, suggesting that language may encourage a general mode of schematic construal. The study and its findings illustrate a novel approach to examining the perceptual properties of mental representations.

Structure-mapping in metaphor comprehension

Metaphor has a double life. It can be described as a directional process in which a stable, familiar base domain provides inferential structure to a less clearly specified target. But metaphor is also described as a process of finding commonalities, an inherently symmetric process. In this second view, both concepts may be altered by the metaphorical comparison. Whereas most theories of metaphor capture one of these aspects, we offer a model based on structure-mapping that captures both sides of metaphor processing. This predicts (a) an initial processing stage of symmetric alignment; and (b) a later directional phase in which inferences are projected to the target. To test these claims, we collected comprehensibility judgments for forward (e.g., "A rumor is a virus") and reversed ("A virus is a rumor") metaphors at early and late stages of processing, using a deadline procedure. We found an advantage for the forward direction late in processing, but no directional preference early in processing. Implications for metaphor theory are discussed.

Representing causation

The dynamics model, which is based on L. Talmy's (1988) theory of force dynamics, characterizes causation as a pattern of forces and a position vector. In contrast to counterfactual and probabilistic models, the dynamics model naturally distinguishes between different cause-related concepts and explains the induction of causal relationships from single observations. Support for the model is provided in experiments in which participants categorized 3-D animations of realistically rendered objects with trajectories that were wholly determined by the force vectors entered into a physics simulator. Experiments 1-3 showed that causal judgments are based on several forces, not just one. Experiment 4 demonstrated that people compute the resultant of forces using a qualitative decision rule. Experiments 5 and 6 showed that a dynamics approach extends to the representation of social causation. Implications for the relationship between causation and time are discussed.

Models of causation and the semantics of causal verbs

This research examines the relationship between the concept of CAUSE as it is characterized in psychological models of causation and the meaning of causal verbs, such as the verb cause itself. According to focal set models of causation (; ), the concept of CAUSE should be more similar to the concepts of ENABLE and PREVENT than either is to each other. According to a model based on theory of force dynamics, the force dynamic model, the concepts of CAUSE, ENABLE, and PREVENT should be roughly equally similar to one another. The relationship between these predictions and the meaning of causal verbs was examined by having participants sort causal verbs and rate them with respect to the dimensions specified by the two models. The results from five experiments indicated that the force dynamic model provides a better account of the meaning of causal verbs than do focal set models of causation. Implications for causal inference and induction are discussed.

Direct causation in the linguistic coding and individuation of causal events

This research proposes a new theory of direct causation and examines how this concept plays a key role in the linguistic coding and individuation of causal events. According to the no-intervening-cause hypothesis, a causal chain can be described by a single-clause sentence and construed as a single event if there are no intervening causers between the initial causer and the final causee. Consistent with this hypothesis, participants used single-clause sentences (lexical causatives) more often than two-clause sentences (e.g. periphrastic causatives) for causal chains in which (1) the causer and causee touched (Experiments 1 and 2), and (2) an intervening entity could be construed as an enabling condition rather than another cause (Experiments 2-4). In addition, event judgments paralleled linguistic descriptions: chains that could be described with single-clause expressions were more often construed as single events than chains that could not (Experiments 1-3). Implications for languages other than English, for the linguistic coding of accidental outcomes and for the relationship between cognition and language in general are discussed.

Iodine deficiency during infancy and early childhood in Belgium: does it pose a risk to brain development?

Iodine deficiency is well documented in Belgium in adults including pregnant women, adolescents, schoolchildren, and neonates, but no data are available in the age group 6 months-3 years. We investigated the status of iodine nutrition in 111 healthy subjects in this age group in an attempt to evaluate the risk of brain damage due to iodine deficiency in Belgium. In 244 causal urine samples collected in these subjects, the median concentration of iodine was 101 micrograms/l vs 180-220 micrograms/l under normal conditions. The daily supplementation of the subjects with a physiological dose of 90 micrograms iodine was followed by a slow and progressive increase of urinary iodine, which reached a normal level only after a delay of about 30 weeks of therapy. This observation suggests that part of the supplement of iodine offered to the children was stored in their thyroid glands until the iodine content of the gland had reverted to normal, reflecting the state of hyperavidity of the thyroid for iodide characteristic of iodine deficiency. In conclusion, infants and young children in Belgium are as iodine deficient as all other age groups of the population and, consequently, are at risk of brain damage. This works further illustrates the need for systematic iodine supplementation of the population in Belgium.

Randomized trial of choledochocholedochostomy with or without a T tube in orthotopic liver transplantation

OBJECTIVE

To compare the incidence of biliary complications after liver transplantation in patients undergoing choledochocholedochostomy reconstruction with or without T tube in a multicenter, prospective, randomized trial.

SUMMARY BACKGROUND DATA

Several reports have suggested that biliary anastomosis without a T tube is a safe method of biliary reconstruction that could avoid complications related to the use of T tubes. No large prospective randomized trial has so far been published to compare the two techniques.

METHODS

One hundred eighty recipients of orthotopic liver transplantation were randomly assigned to choledochocholedochostomy with (n = 90) or without (n = 90) a T tube in six French liver transplantation centers. All types of biliary complications were taken into account.

RESULTS

The overall biliary complication rate was increased in the T-tube group, even though these complications did not lead to an increase in surgical or radiologic therapeutic procedures. The major significant complication was cholangitis in the T-tube group; this did not occur in the other group. The incidence of biliary fistula was 10% in the T-tube group and 2.2% in the group without a T tube. Other biliary complications were similar. The complication rate of cholangiography performed with the T tube was greater than with other types of biliary exploration. The graft and patient survival rates were similar in the two groups.

CONCLUSION

This study is the first large prospective, randomized trial of biliary complications with or without a T tube. The authors found an increase in the biliary complication rate in the T-tube group, which was linked to minor complications. The T tube did not provide a safer access to the biliary tree compared with the others types of biliary explorations. The authors recommend the performance of choledochocholedochostomy without a T tube in liver transplantation.

Evidence for role-neutral initial processing of metaphors

Two models of metaphor processing are contrasted. The structure-mapping model postulates an initially role-neutral alignment process, followed by directional projection of inferences. The attributive categorization model postulates role-specific processing throughout comprehension. To test between these models, the early stages of metaphor comprehension were probed using a technique based on S. Glucksberg, P. Gildea, and H. Bookin's (1982) finding that metaphorical meaning interferes with literal truthfulness judgments. In Experiment 1, interference effects did not differ between normal metaphors and metaphors with reversed terms, suggesting that initial processing is role-neutral. In Experiment 2, we again found no role dependence in interference effects, even for highly conventional metaphors. In Experiment 3, it was verified that (a) full comprehension is role-sensitive and (b) full comprehension reaction times (RTs) are far longer than interference RTs, buttressing the claim that interference is an early-stage effect. Overall, the results support the structure-mapping model of metaphor processing.

Evidence for role-neutral initial processing of metaphors

Two models of metaphor processing are contrasted. The structure-mapping model postulates an initially role-neutral alignment process, followed by directional projection of inferences. The attributive categorization model postulates role-specific processing throughout comprehension. To test between these models, the early stages of metaphor comprehension were probed using a technique based on S. Glucksberg, P. Gildea, and H. Bookin's (1982) finding that metaphorical meaning interferes with literal truthfulness judgments. In Experiment 1, interference effects did not differ between normal metaphors and metaphors with reversed terms, suggesting that initial processing is role-neutral. In Experiment 2, we again found no role dependence in interference effects, even for highly conventional metaphors. In Experiment 3, it was verified that (a) full comprehension is role-sensitive and (b) full comprehension reaction times (RTs) are far longer than interference RTs, buttressing the claim that interference is an early-stage effect. Overall, the results support the structure-mapping model of metaphor processing.

[Non-surgical treatments of esophageal cancers]

INTRODUCTION

Despite improvements in surgical techniques and perioperative mortality, only slight improvements in the 5-year survival of patients with esophageal cancer have been observed in the last 20 years. Many patients with apparently localized cancer will have recurrences or metastatic disease despite surgery with curative resection. Consequently, multimodal therapies, including chemotherapy and radiotherapy, were introduced. This review outlines and critically analyzes current non-surgical treatments, including palliative care.

CURRENT KNOWLEDGE AND KEY POINTS

Esophageal cancers appear to be chemosensitive but the median duration of response is short and toxicity consistent, especially in metastatic disease. Consequently, palliative chemotherapy should be offered preferably within a clinical trial. Chemotherapy as the only adjuvant treatment cannot be recommended outside clinical trials. Radiotherapy alone as a curative treatment has been proven to be inferior to chemoradiotherapy in inoperable tumors. Some data support the use of preoperative chemoradiotherapy, but randomized trials are conflicting. A pathological complete response has been identified as a favorable prognostic factor for survival. Self-expanding esophageal metal stents are a simple and effective palliative treatment of malignant dysphagia and can be considered as the reference treatment in patients with obstruction of the lower esophagus or with fistula.

FUTURE PROSPECTS AND PROJECTS

Taxanes should be evaluated in randomized studies using chemotherapy or chemo-radiotherapy. Progress in radiotherapy, such as accelerated fractionation, greater radiation dose, and the addition of brachytherapy, will increase locoregional control and probably survival. The role of secondary surgery in patients responding to chemoradiotherapy still needs to be answered.

Evolution and devolution of folkbiological knowledge

In this paper we present evidence in support of the hypothesis that the average person's knowledge about trees, and about the natural world in general, has declined during the 20th century. Our investigations are based on examination of a large sample of written material from the 16th through 20th centuries contained in the Oxford English Dictionary. In Analysis 1, we show a precipitous decline in the use of tree terms after, but not before, the 19th century. In Analysis 2, we analyze tree terms at different levels of organization and show that the decline observed in Analysis 1 occurs for all levels of organization. This second analysis also reveals that during the 16th to 19th centuries tree terms became progressively more specific, suggesting that during these periods knowledge about trees increased. In Analysis 3, we show similar rates of decline in other folkbiological categories, indicating that the change in tree terms reflects a general decline in knowledge about living kinds. Also in Analysis 3, we show that several non-biological categories have experienced evolution during the 20th century, indicating that the declines in the 20th century for folkbiological categories are not an inevitable outcome of the corpus. Finally, Analysis 4 also shows declines in the frequency of quotations for which the tree term was not the topic of the sentence, and thus incidental to the purposes of the writer. The results from Analysis 4 reassure us that the results from Analyses 1-3 were not solely due to change in the aims and purposes of writers over the centuries. In sum, the analyses indicate that in the domain of trees, there has been a long and sustained period of conceptual evolution followed by a recent pronounced period of devolution.

Characterization of myosin V from PC12 cells

PC12 cell line is a cellular model to study neurite outgrowth and neurotransmitter release mechanisms. Molecular motors may be involved in these responses and myosin V could be a candidate to mediate these effects. Overlay experiments using [(125)I]-calmodulin showed that PC12 cells possess several calmodulin-binding proteins, some of them around 190-210 kDa. Western blots using affinity purified polyclonal antibodies raised against chicken brain myosin V revealed a component of 190 kDa, a molecular mass typical of myosin V. Furthermore, Northern blots using a myosin V probe also detected a transcript of around 12 kbp. Immunofluorescence cytochemistry demonstrated the localization of myosin V throughout the cytoplasm, in the neurites, growth cone tips, and with an intense asymmetrical perinuclear labeling. Western blot analyses of PC12 cellular extracts after FGF-2 and/or dibutyryl cAMP treatment revealed variations between myosin V and myosin II expression during neuronal differentiation. These results demonstrated the presence of myosin V in PC12 cells and also suggest a role for this motor molecule in the neuronal differentiation response in PC12 cells.