Abstract P5-07-01: Computational scoring of tumor infiltrating lymphocytes in triple-negative breast cancer

Background: Stromal Tumor Infiltrating Lymphocytes (sTIL) are an established prognostic feature in triple-negative breast cancer, yet manual assessment or visual estimation of sTILs with conventional light microscopy may be subject to inter-pathologist variability. Recently published guidelines by the International TIL Working Group help address inter-pathologist variability, yet there remains a need for more objective and quantitative computational sTIL scoring.

Methods: Our study used 120 triple-negative breast cancer slides (one slide per patient). A deep-learning based image analysis workflow is used to perform segmentation and classification of tissue regions and cells on the digital whole slide image. We used 14 annotated slides to train and validate the deep learning model, and to obtain image segmentation and classification accuracy statistics. Non-training slides were used to evaluate the concordance of manual (m-sTIL) and computationally derived (c-sTIL) scores. To generate data to create the model we manually annotated tissue regions in FFPE H&E stained digital slides, including: tumor, stroma, and necrosis. Initial classification of cell nuclei was performed using a semi-automated image analysis method, and then manually corrected to generate ground truth for tumor, stroma (fibroblasts), and lymphocytes. All annotations were performed by a trained research fellow and reviewed by a board-certified pathologist. Corresponding region and nucleus-level annotations were combined to train and validate a fully-convolutional neural network that jointly classifies tissue regions and cell nuclei. Tissue region segmentation accuracy was assessed by the Dice coefficient to measure degree of overlap between predicted tissue regions and ground truth annotations. Cell classification accuracy was assessed using area under curve (AUC). Two board-certified pathologists independently generated an m-sTIL score for all slides according to clinical guidelines, and discrepancies between pathologists were resolved by consensus. c-sTIL scores were calculated as the percentage of classified stromal areas occupied by nuclei classified as lymphocytic infiltrates.

Results: Tissue region segmentation was accurate for both stroma (0.77 Dice) and tumor (0.83 Dice) regions, and accurate overall (0.78 Dice). Cell classification was highly accurate for lymphocytes (0.89 AUC), tumor cells (0.90 AUC), stromal cells (0.78 AUC), and overall (0.89 AUC, micro average). Inter observer spearman correlation between the m-sTIL scores of our two pathologists was 0.66 (p < 0.001). By comparison, the correlation between c-sTIL and consensus m-sTIL was higher at 0.73 (p < 0.001). Dichotomizing at a threshold sTIL score of 10%, c-sTIL scoring identifies low-sTIL patients with an accuracy of 85%. High- and Low- sTIL score patient groups show clear separation on a Kaplan-Meier curve for both c-sTIL and m-sTIL scoring approaches.

Conclusions: Our pipeline quantifies stromal TILs with high concordance with manual pathologist scores, and sheds light on the ability of computational approaches in standardizing diagnostic pathology workflows. Future work will investigate how other computationally driven histology biomarkers can predict outcomes and help prognosticate breast cancer patients.

Citation Format: Amgad M, Sarkar A, Srinivas C, Redman R, Ratra S, Bechert CJ, Calhoun BC, Mrazeck K, Kurkure U, Cooper LA, Barnes M. Computational scoring of tumor infiltrating lymphocytes in triple-negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-07-01.

Better Respiratory Education and Treatment Help Empower (BREATHE) study: Methodology and baseline characteristics of a randomized controlled trial testing a transitional care program to improve patient-centered care delivery among chronic obstructive pulmonary disease patients

BACKGROUND

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of hospitalizations. Interventional studies focusing on the hospital-to-home transition for COPD patients are few. In the BREATHE (Better Respiratory Education and Treatment Help Empower) study, we developed and tested a patient and family-centered transitional care program that helps prepare hospitalized COPD patients and their family caregivers to manage COPD at home.

METHODS

In the study's initial phase, we co-developed the BREATHE transitional care program with COPD patients, family-caregivers, and stakeholders. The program offers tailored services to address individual patients' needs and priorities at the hospital and for 3months post discharge. We tested the program in a single-blinded RCT with 240 COPD patients who were randomized to receive the program or 'usual care'. Program participants were offered the opportunity to invite a family caregiver, if available, to enroll with them into the study. The primary outcomes were the combined number of COPD-related hospitalizations and Emergency Department (ED) visits per participant at 6months post discharge, and the change in health-related quality of life over the 6months study period. Other measures include 'all cause' hospitalizations and ED visits; patient activation; self-efficacy; and, self-care behaviors.

DISCUSSION

Unlike 1month transitional care programs that focus on patients' post-acute care needs, the BREATHE program helps hospitalized COPD patients manage the post discharge period as well as prepare them for long term self-management of COPD. If proven effective, this program may offer a timely solution for hospitals in their attempts to reduce COPD rehospitalizations.

Structural Representations of Objects: Invariance over a Shape-Distorting Transformation

Object perception seems robust over changes in properties such as rotation, reflection, and size. Such changes, however, are shape preserving. To investigate the effect of changes that disrupt overall shape yet keep the global relations among the parts intact, a set of objects was scaled by 50% along just the x-axis. Compression or expansion along a single axis markedly affects the overall shape of an object but leaves the global relations among the parts intact. In an initial encoding phase, subjects viewed images of symmetric and asymmetric three-dimensional nonsense objects and determined whether each faced principally to the left or right. We have previously found that such judgments require subjects to process the objects as global three-dimensional forms. In a subsequent test phase, subjects judged whether a set of both studied and novel objects were symmetric or asymmetric. Half of the studied items were either compressed or expanded along the x-axis in the test presentation. The magnitude of priming was equivalent for the transformed and the untransformed objects. In a second experiment, subjects performed the same initial left/right encoding task followed by a recognition test that assessed explicit memory for the previously presented objects. Although subjects were instructed to disregard changes in scale, recognition performance was reliably better for the untransformed objects. These results support the role of a structural representation system that captures the global relations among the parts and the principal axis of an object and an episodic system which also encodes features of shape.

Preserved priming of novel objects in patients with memory disorders

Amnesic patients perform poorly on explicit memory tests that require conscious recollection of recent experiences, but frequently show preserved facilitations of performance or priming effects on implicit memory tasks that do not require conscious recollection. We examined implicit memory for novel visual objects on an object decision test in which subjects decide whether structurally possible and impossible objects could exist in three-dimensional form. Patients with organic memory disorders showed robust priming effects on this task---object decision accuracy was higher for previously studied objects than for nonstudied objects---and the magnitude of priming did not differ from matched control subjects or college students. However, patients showed impaired explicit memory for novel visual objects on a recognition test. We argue that priming is mediated by the structural description system, a subsystem of the perceptual representation system, that operates at a presemantic level and is preserved in amnesic patients.

Micrometastases and isolated tumour cells in sentinel lymph nodes in oral and oropharyngeal squamous cell carcinoma

BACKGROUND

The occurrence of micrometastases (MMs) and isolated tumour cells (ITCs) in oral sentinel lymph node (SLN) biopsy is poorly known, and the definitions and clinical significance of MMs and ITCs in SLN biopsy are controversial. We compared the UICC/TNM definitions of MMs and ITCs with our previously published sentinel node protocol to assess how the adoption of the UICC/TNM criteria would affect the staging of nodal micrometastatic disease.

METHODS

Of 107 patients who had a SLN biopsy and pathology at 150 microm intervals, 35 with metastatic tumour were included. Eighty-six SLNs were reassessed using the UICC/TNM definitions for MMs and ITCs. Findings were linked to the final pathology in the subsequent neck dissection.

RESULTS

Initial H&E sections showed metastases in 24 patients (in 34 out of 61 SLN), 8 of whom (9 SLNs) had MMs. Additional step serial sections revealed metastatic deposits in a further 11 patients (15 out of 25 SLNs were positive) which were reassessed as MMs (6 patients) or ITCs (5 patients). Subsequent neck dissection revealed additional metastases in 46% of patients with MM, whilst one of the ITC patients had subsequent neck metastases (20%).

CONCLUSION

Despite some limitations, the UICC/TNM classification provides an objective, uniform method of detecting MMs and ITC's. Unlike in cases with ITC, metastases in other non-SLNs were common when a micrometastasis was detected in a SLN, indicating need for further treatment of the neck.

The contribution of sociodemographic, medical, and attitudinal factors to blood donation among the general public

BACKGROUND

Few studies have simultaneously assessed the relative importance of sociodemographic, medical, and attitudinal factors in explaining which individuals are more likely to donate blood.

STUDY DESIGN AND METHODS

A cross-sectional telephone survey of households in Maryland was conducted to identify the relation of sociodemographic, medical, and attitudinal factors to blood donation history among the general public. Random digit dialing was used to identify households; individuals aged 18 to 75 years were randomly selected within households. In multivariate analyses, the independent relationship of these factors with prior history of blood donation was assessed, and the amount of variation in prior history of blood donation among the study population that could be explained by these factors was determined.

RESULTS

Of 385 participants (84% of randomized homes), 228 (59%) had donated blood at least once in the past. After adjusting for potential confounders, women, black participants, and those agreeing with the statement "I am afraid of hospitals" had 60 to 80 percent lower odds of prior donation when compared with men, white participants, and those who did not agree with the statement (OR [95% CI]: 0.2 [0.1-0.4], 0.4 [0.2-0.8], and 0.3 [0.2-0.6], respectively). The effect of fear of hospitals was consistent across sex and race. Trust, fear, and suspicion of hospitals were among factors contributing most to variation in prior donation history.

CONCLUSION

Female sex, black race, and fear of hospitals are three major factors negatively associated with prior history of blood donation. Fear of hospitals affects blood donation patterns across race and sex groups. Future study is needed to determine whether recruitment of blood donors may be more efficient if focused toward women, minorities, and donors' fears of healthcare facilities or hospitals.

Patient perspectives on spirituality and the patient-physician relationship

OBJECTIVE

To identify the preferences and concerns of seriously ill patients about discussing religious and spiritual beliefs with physicians.

DESIGN

Three focus group discussions with patients who had experienced a recent life-threatening illness. Discussions were audiotaped, transcribed verbatim, and reviewed independently by two investigators to identify discrete comments for grouping into domains. A third investigator adjudicated differences in opinion. Comments were then independently reviewed for relevance and consistency by a health services researcher and a pastoral counselor.

SETTING

Academic medical center.

PARTICIPANTS

Referred sample of 22 patients hospitalized with a recent life-threatening illness.

MEASUREMENTS AND MAIN RESULTS

Almost all of the 562 comments could be grouped into one of five broad domains: 1) religiosity/spirituality, 2) prayer, 3) patient-physician relationship, 4) religious/spiritual conversations, and 5) recommendations to physicians. God, prayer, and spiritual beliefs were often mentioned as sources of comfort, support, and healing. All participants stressed the importance of physician empathy. Willingness to participate in spiritual discussions with doctors was closely tied to the patient-physician relationship. Although divided on the proper context, patients agreed that physicians must have strong interpersonal skills for discussions to be fruitful. Physician-initiated conversation without a strong patient-physician relationship was viewed as inappropriate and as implying a poor prognosis.

CONCLUSION

Religion and spirituality are a source of comfort for many patients. Although not necessarily expecting physicians to discuss spirituality, patients want physicians to ask about coping and support mechanisms. This exploratory study suggests that if patients then disclose the importance of spiritual beliefs in their lives, they would like physicians to respect these values.

How important is intrinsic spirituality in depression care? A comparison of white and African-American primary care patients

We used a cross-sectional survey to compare the views of African-American and white adult primary care patients (N = 76) regarding the importance of various aspects of depression care. Patients were asked to rate the importance of 126 aspects of depression care (derived from attitudinal domains identified in focus groups) on a 5-point Likert scale. The 30 most important items came from 9 domains: 1) health professionals' interpersonal skills, 2) primary care provider recognition of depression, 3) treatment effectiveness, 4) treatment problems, 5) patient understanding about treatment, 6) intrinsic spirituality, 7) financial access, 8) life experiences, and 9) social support. African-American and white patients rated most aspects of depression care as similarly important, except that the odds of rating spirituality as extremely important for depression care were 3 times higher for African Americans than the odds for whites.

The influence of task requirements on priming in object decision and matching

We argue that task requirements can be the determinant in generating different results in studies on visual object recognition. We investigated priming for novel visual objects in three implicit memory tasks. A study-test design was employed in which participants first viewed line drawings of unfamiliar objects and later made different decisions about structural aspects of the objects. Priming for both symmetric and asymmetric possible objects was observed in a task requiring a judgment of structural possibility. However, when the task was changed to one requiring a judgment of structural symmetry, only symmetric possible objects showed priming. Finally, in a matching task in which participants made a same-different judgment, only symmetric possible objects exhibited priming. These results suggest that an understanding of object representation will be most fruitful if it is based on careful analyses of both the task demands and their interaction(s) with encoding and retrieval processes.

Differential evolution of eastern equine encephalitis virus populations in response to host cell type

Arthropod-borne viruses (arboviruses) cycle between hosts in two widely separated taxonomic groups, vertebrate amplifying hosts and invertebrate vectors, both of which may separately or in concert shape the course of arbovirus evolution. To elucidate the selective pressures associated with virus replication within each portion of this two-host life cycle, the effects of host type on the growth characteristics of the New World alphavirus, eastern equine encephalitis (EEE) virus, were investigated. Multiple lineages of an ancestral EEE virus stock were repeatedly transferred through either mosquito or avian cells or in alternating passages between these two cell types. When assayed in both cell types, derived single host lineages exhibited significant differences in infectivity, growth pattern, plaque morphology, and total virus yield, demonstrating that this virus is capable of host-specific evolution. Virus lineages grown in alternation between the two cell types expressed intermediate phenotypes consistent with dual adaptation to both cellular environments. Both insect-adapted and alternated lineages greatly increased in their ability to infect insect cells. These results indicate that different selective pressures exist for virus replication within each portion of the two-host life cycle, and that alternation of hosts selects for virus populations well adapted for replication in both host systems.

Screening the public for depression through the Internet

OBJECTIVE

Despite increased public screening, many individuals with depression remain undetected or untreated. This study explored the performance of an Internet-based program in screening for depression.

METHODS

The Centers for Epidemiological Studies Depression (CES-D) scale was adapted as an online screening test. The program advised persons whose score indicated a high probability of depression to seek treatment and asked them to complete a survey of attitudes and preferences that could be printed and taken to a health professional. Responses were collected anonymously for epidemiologic research. Demographic characteristics of participants were compared with those of the U.S. population and participants in previous community screenings. The costs of the program were calculated.

RESULTS

The CES-D scale was completed 24,479 times during the eight-month study period. The respondents' median age category was 30 to 45 years, and almost 30 percent were male; 58 percent (N=14,185) screened positive for depression, and fewer than half of those had never been treated for depression. The proportion of younger individuals was larger than in previous public screenings, but was still lower than that in the U.S. population. Our sample contained a lower proportion of minorities than the U.S. population (16.6 percent versus 28.3 percent). Sunk costs totaled $9,000, and additional marginal costs to maintain the system totaled $3,750.

CONCLUSIONS

The Internet provides a continuously available, inexpensive, easily maintained platform to anonymously screen a large number of individuals from a broad geographic area. However, older adults and minorities may visit screening sites less frequently than other populations.

Analysis of FAK-associated signaling pathways in the regulation of cell cycle progression

Focal adhesion kinase (FAK) is an important mediator of signal transduction pathways initiated by integrins in cell migration, survival and cell cycle regulation. The ability of FAK to mediate integrin signaling in the regulation of cell cycle progression depends on the phosphorylation of Tyr397, which implies a functional significance for the formation of FAK signaling complexes with Src, phosphatidylinositol-3-kinase (PI3K) and Grb7. We have previously described a FAK mutant, D395A, that selectively disrupts FAK binding to PI3K, but allows FAK association with Src. Using this mutation in a mislocalized FAK mutant background, we show here that formation of a FAK/PI3K complex is not sufficient for cell cycle progression but the formation of a FAK/Src complex plays an essential role. We also show that mutation of D395 to A disrupted FAK association with Grb7. This suggests that a FAK/Grb7 complex is not involved in the cell cycle regulation either, which is supported by direct analysis of cells expressing a dominant negative Grb7 construct. Finally, we provide evidence that the Src-dependent association of FAK with Grb2 and p130(Cas) are both required for the regulation of cell cycle progression by FAK. Together, these studies identify important FAK downstream signaling pathways in cell cycle regulation.

Effects of initial dose on eastern equine encephalomyelitis virus dependent mortality in intrathoracically inoculated Culiseta melanura (Diptera: Culicidae)

Viral growth characteristics that favor rapid and prodigious virion production may increase virus transmission but be detrimental to infected hosts. Several arboviruses, including eastern equine encephalomyelitis (EEE) virus, negatively affect the survival of their infected mosquito vectors. To test the hypothesis that the mosquito virulent properties of EEE virus are caused by the presence of intrinsic viral growth properties, we investigated the effects of infecting dose on the survival of intrathoracically inoculated Culiseta melanura (Coquillett). Daily survival of age-matched females inoculated with either a low initial dose of 10(1.5) plaque-forming units (PFUs) per mosquito or a high initial dose of 10(5.5) PFUs per mosquito was monitored for 8 wk. Compared with diluent inoculated controls, mosquitoes from both dosage groups displayed highly significant decreases in survival. No significant differences in daily survival were detected between the two infected groups. Virus production within inoculated mosquitoes was assessed by sampling mosquitoes every 12 h for 96 h after inoculation. Rapid virus amplification occurred in both dosage groups, and by 24 h after exposure the mean viral loads in mosquitoes inoculated with the low dose were comparable to those inoculated with the high dose. Likewise, although detectable virions appeared sooner in the saliva of high dosage mosquitoes, by 72 h after inoculation no significant differences in virus transmission were detected between the two exposure groups. These results indicate that the virulence of EEE virus for its enzootic North American mosquito vector is not dosage dependent and likely reflects the inherent growth properties of this virus within infected mosquitoes.

A simple restriction fragment length polymorphism-based strategy that can distinguish the internal genes of human H1N1, H3N2, and H5N1 influenza A viruses

A simple molecular technique for rapid genotyping was developed to monitor the internal gene composition of currently circulating influenza A viruses. Sequence information from recent H1N1, H3N2, and H5N1 human virus isolates was used to identify conserved regions within each internal gene, and gene-specific PCR primers capable of amplifying all three virus subtypes were designed. Subtyping was based on subtype-specific restriction fragment length polymorphism (RFLP) patterns within the amplified regions. The strategy was tested in a blinded fashion using 10 control viruses of each subtype (total, 30) and was found to be very effective. Once standardized, the genotyping method was used to identify the origin of the internal genes of 51 influenza A viruses isolated from humans in Hong Kong during and immediately following the 1997-1998 H5N1 outbreak. No avian-human or H1-H3 reassortants were detected. Less than 2% (6 of 486) of the RFLP analyses were inconclusive; all were due to point mutations within a restriction site. The technique was also used to characterize the internal genes of two avian H9N2 viruses isolated from children in Hong Kong during 1999.

Genetic characterization of H3N2 influenza viruses isolated from pigs in North America, 1977-1999: evidence for wholly human and reassortant virus genotypes

Since 1998, H3N2 viruses have caused epizootics of respiratory disease in pigs throughout the major swine production regions of the U.S. These outbreaks are remarkable because swine influenza in North America had previously been caused almost exclusively by H1N1 viruses. We sequenced the full-length protein coding regions of all eight RNA segments from four H3N2 viruses that we isolated from pigs in the Midwestern U.S. between March 1998 and March 1999, as well as from H3N2 viruses recovered from a piglet in Canada in January 1997 and from a pig in Colorado in 1977. Phylogenetic analyses demonstrated that the 1977 Colorado and 1997 Ontario isolates are wholly human influenza viruses. However, the viruses isolated since 1998 from pigs in the Midwestern U.S. are reassortant viruses containing hemagglutinin, neuraminidase and PB1 polymerase genes from human influenza viruses, matrix, non-structural and nucleoprotein genes from classical swine viruses, and PA and PB2 polymerase genes from avian viruses. The HA proteins of the Midwestern reassortant swine viruses can be differentiated from those of the 1995 lineage of human H3 viruses by 12 amino acid mutations in HA1. In contrast, the Sw/ONT/97 virus, which did not spread from pig-to-pig, lacks 11 of these changes.

Primary care patients' opinions regarding the importance of various aspects of care for depression

The objectives of this study were to 1) ascertain the importance of various aspects of depression care from the patient's perspective and 2) select items and scales for inclusion in a new instrument to measure primary care patients' attitudes toward and ratings of depression care. We used a cross-sectional survey at a university-based urban primary care clinic; the subjects were adult patients being recruited for a study of minor depression. To help prioritize attitudinal domains, including 126 items identified previously in focus groups, we asked patients to rate the importance of each aspect of depression care on a five-point scale. Items were ranked according to mean scores and the percentage of patients ranking the items as extremely important. The items were selected for inclusion in an instrument to measure patients' attitudes toward depression care based on their importance ratings. We performed reliability and validity testing of scales comprising the 30 most important items and a shortened version that includes 16 items. The sample included 76 patients (mean age 34.8 years; mean CES-D score, 22.2; 72% women; 36% African-American; 32% college graduates). Forty-six percent had visited a mental health professional in the past. The top 30 items for the overall sample came from the following domains: 1) health care providers' interpersonal skills, 2) primary care provider recognition of depression, 3) treatment effectiveness, 4) treatment problems, 5) patient understanding about treatment, 6) intrinsic spirituality, and 7) financial access to services. Scales comprising items from these domains show adequate internal consistency (Cronbach's alpha >0.70) as well as convergent and discriminant validity. We have designed a brief patient-centered instrument for measuring attitudes toward depression care that has evidence for internal item consistency reliability and discriminant validity.

Evidence for unconscious memory processing during elective cardiac surgery

BACKGROUND

Many anesthetic drugs have been shown to disrupt conscious recall (explicit memory) in volunteers. However, unconscious processing (implicit memory) of intraoperative auditory material may occur during general anesthesia and may provide an opportunity for intraoperative therapeutic intervention. In this study, we examined patients undergoing elective cardiac surgery for evidence of intraoperative implicit and explicit memory.

METHODS AND RESULTS

Twenty-five subjects provided written informed consent and underwent general anesthesia and cardiopulmonary bypass for cardiac surgery. During the operation, patients were randomized to receive 1 of 2 different audiotapes of associated word pairs. Postoperatively, a blinded observer conducted a standardized interview to determine the extent of intraoperative implicit and explicit memory. With the use of free association, significant intraoperative implicit memory was found. In contrast, no patient had spontaneous or directed recall of intraoperative events, and we did not find evidence of intraoperative explicit memory with a recognition task.

CONCLUSIONS

Patients undergoing general anesthesia for cardiac surgery were reliably able to reinforce associations between word pairs solely on the basis of their intraoperative presentation. This provides further evidence that patients are capable of processing intraoperative auditory information.

Effects of size and orientation change on hippocampal activation during episodic recognition: a PET study

To determine whether physical match between studied and tested items influences blood flow increases in the hippocampal formation associated with recognition memory, positron emission tomography (PET) was used to measure changes in regional cerebral blood flow while healthy volunteers made old/new judgements about line drawings of objects. Some objects were tested in the same size and orientation as they had appeared earlier during the study phase of the experiment; other objects were tested in a different size or orientation than when they were studied. Blood flow increases in the vicinity of the hippocampal formation were observed in the same object condition compared with the size change and the orientation change conditions, even though recognition accuracy was affected significantly only by orientation change. Results add to previous findings suggesting that physical similarity between studied items and test cues may contribute to hippocampal activation during episodic retrieval.

Neuroanatomical correlates of implicit and explicit memory for structurally possible and impossible visual objects

Implicit memory refers to nonconscious retrieval of past experience demonstrated by facilitation in test performance on tasks that do not require intentional recollection of previous experiences. Explicit memory, in contrast, refers to the conscious retrieval of prior information, as demonstrated during standard recall and recognition tasks. In this experiment, positron emission tomographic (PET) measurements of regional cerebral blood flow (CBF), a marker of local neuronal activity, were used to identify and contrast brain regions that participate in the perception, implicit memory, and explicit memory for structurally possible and impossible visual objects. Ten CBF images were acquired in 16 normal women as they made possible/impossible and old/new recognition decisions about previously studied (old) and nonstudied (new) structurally possible and impossible objects. As reported previously, object decisions for familiar possible objects were associated with increased CBF in the vicinity of the left inferior temporal and fusiform gyri and recognition memory for familiar possible objects was associated with increased CBF in the vicinity of the right hippocampus. In this report, we provide more extensive analyses of the roles of the inferior temporal cortex, the hippocampus, the parahippocampus, and the pulvinar in encoding and retrieval operations. Additionally, patterns of CBF increases and decreases provide information regarding the neural structures involved in implicit and explicit memory.

Direction of motion influences perceptual identification of ambiguous figures

It is known that the perceived identity of an ambiguous figure can influence how that figure is perceived to move. In 6 experiments, the converse effect-the role of motion in the perceptual identification of ambiguous figures (e.g., N. Tinbergen's, 1951, goose-hawk)-was examined. In general, observers were biased to identify a moving ambiguous figure as that object whose face pointed in the direction of motion. Experiments 1-4 replicated this basic effect over induced, apparent, and smooth motion displays. Results from Experiment 5 show that longer interstimulus intervals led to smaller biases, with all bias disappearing around 1,500 ms. In Experiment 6, direction of motion influenced perceptual identification even in the presence of conflicting shape information.

Direction of motion influences perceptual identification of ambiguous figures

It is known that the perceived identity of an ambiguous figure can influence how that figure is perceived to move. In 6 experiments, the converse effect-the role of motion in the perceptual identification of ambiguous figures (e.g., N. Tinbergen's, 1951, goose-hawk)-was examined. In general, observers were biased to identify a moving ambiguous figure as that object whose face pointed in the direction of motion. Experiments 1-4 replicated this basic effect over induced, apparent, and smooth motion displays. Results from Experiment 5 show that longer interstimulus intervals led to smaller biases, with all bias disappearing around 1,500 ms. In Experiment 6, direction of motion influenced perceptual identification even in the presence of conflicting shape information.

Vector competence of mosquitoes (Diptera:Culicidae) from Massachusetts for a sympatric isolate of eastern equine encephalomyelitis virus

We tested susceptibility to per os infection and potential salivary transmission for eastern equine encephalomyelitis (EEE) virus in Aedes canadensis (Theobald), Aedes vexans (Meigen), Anopheles quadrimaculatus (Say), Anopheles punctipennis (Say), Coquillettidia perturbans (Walker), and Culex salinarius (Coquillett). Culiseta melanura (Coquillett), the documented enzootic vector of EEE virus, was our control. Based on these estimates of laboratory vector competence and other behavioral and ecological components of vectorial capacity, we ranked these 6 species from the most to least probable epidemic vectors: Cx. salinarius, An. quadrimaculatus, Ae. canadensis, Cq. perturbans, Ae. vexans, and An. punctipennis.

Male reproductive success of Schistosoma mansoni-infected Biomphalaria glabrata snails

Infection of Biomphalaria glabrata by Schistosoma mansoni results in a dramatic reduction in the snail's ability to produce eggs. We studied the ability of such parasitically castrated snails to fertilize the eggs of uninfected snails. Pigmented B. glabrata snails (13141 stock) were infected with S. mansoni miracidia and reared individually until they ceased laying eggs. These infected snails were then given the opportunity to mate with uninfected albino (NMRI) snails. Each of the infected snails was paired with a different albino partner each subsequent week. Sperm transfer by the infected snails was evident from the production of pigmented progeny by the uninfected albino snails. Infected snails successfully acted as males for up to 6 wk after parasitic castration had occurred. The duration of allosperm use by uninfected recipients was lengthy, regardless of the infection status of the pigmented sperm donor.

Varieties of visual representation: how are we to analyze the concept of mental image?

This paper presents a selective account of imagery research during the 1970s and 80s, whose chief objective was to establish the functional equivalence of imaginal and perceptual representations. More recent attention to imagery by cognitive neuroscience has extended and solidified this idea of functional equivalence, but it has also introduced conceptual complexities by demonstrating that imagery, like perception and object recognition, may consist of distinguishable subsystems whose representational properties become activated in response to the demands of particular cognitive tasks.

Brain regions associated with retrieval of structurally coherent visual information

An object's global, three-dimensional structure may be represented by a specialized brain system involving regions of inferior temporal cortex. This system's role in object representation can be understood by experiments in which people study drawings of novel objects with possible or impossible three-dimensional structures, and later make either possible/impossible object decisions or old/new recognition decisions about briefly flashed studied and non-studied objects. Although object decisions about possible objects are facilitated by prior study, there is no corresponding facilitation for impossible objects, thereby implicating a system that is specifically involved in the representation of structurally coherent visual objects. Here we show, by positron emission tomography (PET), that increases in blood flow in inferior temporal regions are associated with object decisions about possible but not impossible objects, and that there are increases in the vicinity of the hippocampal formation associated with episodic recognition of possible objects.

Bias in the priming of object decisions: logic, assumption, and data

R. Ratcliff and G. McKoon (1995) describe 7 experiments that led them to conclude that priming of possible but not impossible objects on the object decision task introduced by D.L. Schacter, L.A. Cooper, & S.M. Delaney (1990) is attributable to explicit memory processes that offset a bias to call studied objects "possible." On the basis of this point, Ratcliff and McKoon (1995) claim to have undermined our hypothesis that a structural description system plays an important role in object decision priming. Ratcliff and McKoon (1995) also offer a general critique of multiple memory systems accounts of priming and explicit memory. Ratcliff and McKoon's (1995) arguments are based on an inaccurate characterization of Schacter et al.'s theoretical position; the evidence for Ratcliff and McKoon's (1995) idea that explicit memory offsets bias is weak, and the central assumptions that underlie both Ratcliff and McKoon's (1995) specific experimental manipulations and their general conclusions are questionable.

Schistosoma mansoni: relationship between low fecundity and reduced susceptibility to parasite infection in the snail Biomphalaria glabrata

Biomphalaria glabrata snails which were not susceptible as juveniles to infection by Schistosoma mansoni were selectively bred (by self-fertilization) from the highly susceptible NMRI laboratory snail stock. The susceptibility rate among juvenile snails derived from interbreeding NMRI parents was initially 85-95%, but after several generations of selection, less than 5% of exposed snails became infected by the parasite. Selection for low susceptibility also resulted in a large proportion of snails that displayed low fecundity and produced abnormal egg masses. Individual adult snails which were isolated from an interbreeding population of nonselected NMRI snails usually produced well-developed egg masses each containing 15-30 embryos. However, when juvenile snails from this same population were reared in isolation and not allowed to cross-fertilize, many displayed a pattern of low fecundity and abnormal egg production similar to that observed in the selected low susceptible line. Furthermore, it was found that many of the isolated snails which exhibited low egg production were also not susceptible to parasitic infection.

Implicit and explicit memory for novel visual objects: structure and function

Six experiments compared the effects of structural and functional encoding tasks on implicit and explicit memory for novel objects. Implicit memory was assessed with a possible-impossible object decision test, and explicit memory was assessed with a yes-no recognition test. Results revealed that recognition memory was higher after functional than after structural encoding tasks, whereas priming effects on the object decision test were unaffected by the same manipulations. The priming effects that were observed after functional encoding tasks could be attributed to structural analyses that are carried out in the course of making judgments about functional properties of novel objects. Results are consistent with the hypothesis that implicit memory for novel objects depends on a presemantic structural description system that can operate independently of episodic memory.

Schistosoma mansoni: analysis of an unusual infection phenotype in the intermediate host snail Biomphalaria glabrata

Snails from a B. glabrata stock, selected for nonsusceptibility to the NMRI strain of S. mansoni, exhibited unusual schistosome infections, with multiple sporocysts prominent in the head-foot (foot-sporocysts). When F1 progeny from numerous crosses between well-defined susceptible (S) and resistant (R) parental snails were exposed, 60% of the infected snails also exhibited this unusual phenotype. F1 progeny from S x S snail crosses developed normal infections. Foot-sporocysts usually developed much later than secondary sporocysts of normal infections and before 12 weeks postexposure the tissue reaction surrounding foot-sporocysts was less intense than reactions to sporocysts in other tissues of the body. Cercariae were seen emerging directly from foot-sporocysts. Infection of S x R hybrid progeny by three other strains of S. mansoni also resulted in the production of foot-sporocysts. Development of the foot-sporocyst infection phenotype in progeny from many snail crosses suggests that this phenotype is more common than previously recognized. Over 50% of the F1 progeny from S x R parental crosses developed patent infections, a fact relevant to the possible biological control of schistosomiasis by the introduction of refractory snails into endemic areas.

Implicit and explicit memory for novel visual objects: structure and function

Six experiments compared the effects of structural and functional encoding tasks on implicit and explicit memory for novel objects. Implicit memory was assessed with a possible-impossible object decision test, and explicit memory was assessed with a yes-no recognition test. Results revealed that recognition memory was higher after functional than after structural encoding tasks, whereas priming effects on the object decision test were unaffected by the same manipulations. The priming effects that were observed after functional encoding tasks could be attributed to structural analyses that are carried out in the course of making judgments about functional properties of novel objects. Results are consistent with the hypothesis that implicit memory for novel objects depends on a presemantic structural description system that can operate independently of episodic memory.

Schistosoma mansoni infection in diapausing Biomphalaria glabrata snails: studies of temperature and genetic influences on diapausing behavior

Snails that are capable of undergoing diapause can circumvent unfavorable environmental conditions, including long periods of drought. Studies were performed to investigate possible temperature and/or genetic factors that may trigger lamella formation and diapausing behavior. The influence of diapause in Biomphalaria glabrata snails on susceptibility to Schistosoma mansoni infection and levels of cercarial production was also investigated. Rearing temperatures of 23 degrees C or higher did not induce lamella formation or diapause, regardless of the parental phenotype. However, substantial percentages of progeny from lamellated or lamellated/diapausing parental snails developed lamellae at 18 degrees C and underwent diapause. Only a small percentage of offspring from nonlamellated parents formed lamellae at this temperature. Juvenile snails exposed just prior to diapause, or immediately following a diapause period of three weeks, were highly susceptible to infection by S. mansoni miracidia. Snails that underwent diapause produced comparable or only slightly fewer cercariae than did nondiapausing snails. These studies indicate that diapause in B. glabrata does little to decrease a snail's ability to act as an intermediate host for S. mansoni or to interrupt the development of the parasite. For these reasons, we believe that greater attention should be given to diapausing snail populations when planning field surveys or mollusciciding programs.

Schistosoma mansoni infections in neonatal Biomphalaria glabrata snails

In areas endemic for schistosomiasis, the population dynamics of the snail intermediate hosts have a direct effect on parasite transmission. The present study focused on the potential for neonatal Biomphalaria glabrata snails to become infected with Schistosoma mansoni and to produce cercariae under various conditions. It was found that snails as small as 0.74 mm in shell diameter could survive miracidial penetration and could release cercariae when as small as 1.6 mm in diameter. Cercariae produced by small snails were equally infectious for mice when compared with those shed by larger snails. Likewise, histological examination of neonatally exposed snails revealed normally developing parasites at all stages of infection. It was found that in 2 snail populations expressing either high or low susceptibility to the parasite, peak susceptibility occurred at 25 days of age in both groups. Daily cercarial production for neonatally exposed snails was initially low but increased dramatically as the snails grew, eventually reaching values as high as 2,100 cercariae/snail/day. A moderate to high percentage of snails infected as neonates was eventually capable of simultaneously producing both eggs and cercariae. These studies emphasize the potential importance of neonatal and preadult snails in helping to maintain foci of S. mansoni infection in endemic areas.

Implicit and explicit memory for novel visual objects in older and younger adults

Two experiments examined effects of aging on implicit and explicit memory for novel visual objects. Implicit memory was assessed with an object decision task in which subjects indicated whether briefly exposed drawings represented structurally possible or impossible objects. Explicit memory was assessed with a yes-no recognition task. On the object decision task, old and young subjects both showed priming for previously studied possible objects and no priming for impossible objects; the magnitude of the priming effect did not differ as a function of age. By contrast, the elderly were impaired on the recognition task. Results suggest that the ability to form and retain structural descriptions of novel objects may be spared in older adults.

Implicit and explicit memory for novel visual objects in older and younger adults

Two experiments examined effects of aging on implicit and explicit memory for novel visual objects. Implicit memory was assessed with an object decision task in which subjects indicated whether briefly exposed drawings represented structurally possible or impossible objects. Explicit memory was assessed with a yes-no recognition task. On the object decision task, old and young subjects both showed priming for previously studied possible objects and no priming for impossible objects; the magnitude of the priming effect did not differ as a function of age. By contrast, the elderly were impaired on the recognition task. Results suggest that the ability to form and retain structural descriptions of novel objects may be spared in older adults.

Priming and recognition of transformed three-dimensional objects: Effects of size and reflection

In 2 experiments exploring memory for unfamiliar 3-dimensional objects, Ss studied drawings under conditions that encouraged encoding of global object structure. Implicit memory for objects was assessed by a judgment of structural possibility; explicit memory was assessed by recognition. The principal manipulation was the relationship between the sizes or the left-right parities of the studied and tested objects. Priming was observed on the possible-impossible object decision task despite transformations of size or reflection. Recognition, by contrast, was significantly impaired by the transformations. These results suggest that a structural description system constructs representations of objects invariant over size and reflection, whereas a separable episodic system encodes these transformations as properties of an object's distinctive representation in memory.

Implicit memory for possible and impossible objects: Constraints on the construction of structural descriptions

Four experiments examined implicit memory or priming effects on an object decision task in which subjects decided whether structurally possible or impossible novel objects could exist in three-dimensional form. Results revealed equivalent levels of priming for possible objects after 1 vs. 4 5-s exposures to the same structural encoding task (Experiment 1) and when objects were studied with a single structural encoding task or 2 different structural encoding tasks (Experiment 3). Explicit memory, by contrast, was greatly affected by both manipulations. However, priming of possible objects was not observed when Ss were given only a single 1-s exposure to perform a structural encoding task (Experiment 2). No evidence for priming of impossible objects was observed in any of the 4 experiments. The data suggest that object decision priming depends on a presemantic structural description system that is distinct from episodic memory.

Implicit memory for possible and impossible objects: constraints on the construction of structural descriptions

Four experiments examined implicit memory or priming effects on an object decision task in which subjects decided whether structurally possible or impossible novel objects could exist in three-dimensional form. Results revealed equivalent levels of priming for possible objects after 1 vs. 4 5-s exposures to the same structural encoding task (Experiment 1) and when objects were studied with a single structural encoding task or 2 different structural encoding tasks (Experiment 3). Explicit memory, by contrast, was greatly affected by both manipulations. However, priming of possible objects was not observed when Ss were given only a single 1-s exposure to perform a structural encoding task (Experiment 2). No evidence for priming of impossible objects was observed in any of the 4 experiments. The data suggest that object decision priming depends on a presemantic structural description system that is distinct from episodic memory.

Mental representation of three-dimensional objects in visual problem solving and recognition

Subjects inspected sets of flat, separated orthographic projections of surfaces of potential three-dimensional objects. After solving problems based on these orthographic views, subjects discriminated between isometric views of the same objects and drawings of distractor structures. Recognition of the isometrics, which had never been shown during the problem solving phase of the experiment, was excellent. In addition, recognition of isometrics corresponding to problems that had been solved correctly when presented in orthographic form was significantly superior to recognition of isometrics based on problems solved incorrectly. In Experiment 2, conditions were included in which either orthographic or isometric views functioned as problem solving or recognition displays. Only in the case of orthographic problem solving followed by isometric recognition (Experiment 1) was the superiority of recognition for correctly-solved problems over incorrectly-solved problems obtained. The pattern of results suggests that viewers construct mental representations embodying structural information about integrated, three-dimensional objects when asked to reason about flat, disconnected projections.

Implicit memory for unfamiliar objects depends on access to structural descriptions

We investigated implicit memory for unfamiliar objects with a task in which subjects decided whether structurally possible and impossible line drawings could exist in three-dimensional space. In Experiment 1, significant priming effects on object decision performance were observed after encoding of global, three-dimensional object structure but not local, two-dimensional object features. Explicit memory did not differ significantly as a function of global vs. local study processing. In Experiments 2 and 3, elaborative encoding had different effects on object decision and recognition performance, thus providing evidence for functional dissociation between implicit and explicit memory. Stochastic independence between object decision and recognition performance was also observed. Results were consistent with the hypothesis that implicit memory, as indexed by priming on the object decision task, depends on encoding of and access to structural descriptions of objects.

Mental representation of three-dimensional objects in visual problem solving and recognition

Subjects inspected sets of flat, separated orthographic projections of surfaces of potential three-dimensional objects. After solving problems based on these orthographic views, subjects discriminated between isometric views of the same objects and drawings of distractor structures. Recognition of the isometrics, which had never been shown during the problem solving phase of the experiment, was excellent. In addition, recognition of isometrics corresponding to problems that had been solved correctly when presented in orthographic form was significantly superior to recognition of isometrics based on problems solved incorrectly. In Experiment 2, conditions were included in which either orthographic or isometric views functioned as problem solving or recognition displays. Only in the case of orthographic problem solving followed by isometric recognition (Experiment 1) was the superiority of recognition for correctly-solved problems over incorrectly-solved problems obtained. The pattern of results suggests that viewers construct mental representations embodying structural information about integrated, three-dimensional objects when asked to reason about flat, disconnected projections.

Re-establishing a life cycle of Schistosoma mansoni from cryopreserved larvae

To study the feasibility of re-establishing a life cycle of Schistosoma mansoni (NMRI strain) from cryopreserved larvae, schistosomules were suspended in the cryoprotectant 1,2-ethanediol and cryopreserved in liquid nitrogen. Mice were injected intramuscularly with samples thawed after 3 days, 3 wk, or 6 mo in liquid nitrogen storage. Two to 5% of the cryopreserved larvae and approximately 18% of corresponding unfrozen control larvae developed into adult worms. Infectivity did not decrease as a function of storage time. The adult worms showed no structural damage or changes in overall size and morphology when examined by light and transmission electron microscopy. Female worms derived from cryopreserved larvae had the same or slightly elevated egg production as controls, but tissue egg distributions were comparable. Subsequent passages through Biomphalaria glabrata snails and mice revealed no difference in snail prepatent death rate, percentage of snails infected, cercarial production per snail, or cercarial infectivity.

The induction of mycelial development inAureobasidium pullulans (IMI 45533) by yeast extract

Germ tube and subsequent mycelial development from yeast-like and swollen cells of Aureobasidium pullulans (IMI 45533) was induced by yeast extract in defined liquid medium. This morphogenetic transition was dependent on inoculum size; pH effects were not involved and once mycelial development was induced in the cells it continued even in the absence of yeast extract. The progeny of mycelium and future generations were unaffected by yeast extract. Cessation of germination was not due to any obvious medium changes but appeared to be partly due to the production of a germination inhibitor, which could also be produced by control cells grown in the absence of yeast extract.

Differentiation and melanin production in hyaline and pigmented strains of Microdochium bolleyi

The effect of various compounds on growth, melanin biosynthesis and cell differentiation was studied in a hyaline (SH25) and a pigmented (SH25B) strain of Microdochium bolleyi. Dark pigment production by the hyaline strain was induced by the presence of DOPA and indole in the medium, both of which are intermediates in the tyrosine pathway of melanin biosynthesis. These substrates also induced conidia and chlamydospore production, structures which were not normally seen in the hyaline strain. The systemic fungicide, tricyclazole, inhibited melanin synthesis in the pigmented strain but not the development of chlamydospore-like cell structures.