Neural processing in the primary auditory cortex following cholinergic lesions of the basal forebrain in ferrets

Cortical acetylcholine (ACh) release has been linked to various cognitive functions, including perceptual learning. We have previously shown that cortical cholinergic innervation is necessary for accurate sound localization in ferrets, as well as for their ability to adapt with training to altered spatial cues. To explore whether these behavioral deficits are associated with changes in the response properties of cortical neurons, we recorded neural activity in the primary auditory cortex (A1) of anesthetized ferrets in which cholinergic inputs had been reduced by making bilateral injections of the immunotoxin ME20.4-SAP in the nucleus basalis (NB) prior to training the animals. The pattern of spontaneous activity of A1 units recorded in the ferrets with cholinergic lesions (NB ACh-) was similar to that in controls, although the proportion of burst-type units was significantly lower. Depletion of ACh also resulted in more synchronous activity in A1. No changes in thresholds, frequency tuning or in the distribution of characteristic frequencies were found in these animals. When tested with normal acoustic inputs, the spatial sensitivity of A1 neurons in the NB ACh- ferrets and the distribution of their preferred interaural level differences also closely resembled those found in control animals, indicating that these properties had not been altered by sound localization training with one ear occluded. Simulating the animals' previous experience with a virtual earplug in one ear reduced the contralateral preference of A1 units in both groups, but caused azimuth sensitivity to change in slightly different ways, which may reflect the modest adaptation observed in the NB ACh- group. These results show that while ACh is required for behavioral adaptation to altered spatial cues, it is not required for maintenance of the spectral and spatial response properties of A1 neurons.

Decision-making as discovery: Vetting clinical research in a leading precision oncology service

Based on fieldwork carried out at the Early Drug Development Service of a world-leading cancer institution, our study sheds lights on decision-making processes at the stage where decisions are made about which clinical trial to pursue and thus which experimental drugs will feed the growing pipeline of molecularly guided therapies and therapeutic strategies available to treating physicians. The paper shows how such collective decision-making practices by a translational research unit employ formal tools and ad hoc valuation strategies that interweave technical-scientific matters of concern with patient-oriented clinical ones, as part of the institutional assetization of biomedical knowledge production. In the process, decision-making practices in part define the conditions of possibility for the provision of care in what is increasingly becoming a 'clinic of variants.' They do so by reconfiguring on an evolving basis the socio-material ecosystem through which precision oncology is enacted as a rapidly evolving assemblage of patients, physicians, research and support staff, protocols, molecular markers, drugs and administrative components.

Organizing precision medicine: A case study of Memorial Sloan Kettering Cancer Center's engagement in/with genomics

Recent decades have seen a dramatic rise of in the number of initiatives designed to promote precision oncology, a domain that has played a pioneering role in the implementation of post-genomic approaches and technologies such as innovative clinical trial designs and molecular profiling. In this paper, based on fieldwork carried out at the Memorial Sloan-Kettering Cancer Center from 2019 onwards, we analyze how a world-leading cancer center has adapted, responded, and contributed to the challenge of "doing" precision oncology by developing new programs and services, and building an infrastructure that has created the conditions for genomic practices. We do so by attending to the "organizing" side of precision oncology and to the nexus between these activities and epistemic issues. We situate the work that goes into making results actionable and accessing targeted drugs within the larger process of creating a precision medicine ecosystem that includes purpose-built institutional settings, thus simultaneously experimenting with bioclinical matters and, reflexively, with organizing practices. The constitution and articulation of innovative sociotechnical arrangements at MSK provides a unique case study of the production of a large and complex clinical research ecosystem designed to implement rapidly evolving therapeutic strategies embedded in a renewed and dynamic understanding of cancer biology.

Cochlear implant outcomes in patients with Meniere's disease: a large case series

OBJECTIVE

To perform a matched cohort study to assess whether patients with Meniere's Disease (MD) require more intensive auditory rehabilitation following cochlear implantation (CI) and identify factors that may affect outcomes in patients with MD.

METHODS

A retrospective case review was performed. MD and control patients were matched for age, biological sex, implant manufacturer and electrode design. Outcomes measured were speech scores, number of visits to audiology department following switch-on, and post-operative active MD.

RESULTS

Forty consecutive implanted MD patients were identified between May 1993 and May 2019. Patients with active MD following CI required significantly more visits to the audiology department compared to controls (P < 0.01) and patients who had inactive MD post-operatively (P < 0.01). However, in MD patients, active MD was less likely following CI (P = 0.03). In patients who continued to experience active MD post-operatively, further medical and surgical ablative intervention was required to control ongoing Meniere's attacks.

CONCLUSION

We present the largest case series of performance outcomes in CI patients with MD. Although speech outcomes in MD patients are comparable to controls, patients with active MD pre-operatively are more likely to experience variation in CI performance requiring a prolonged period of auditory rehabilitation compared to inactive preoperative MD.

SARS-CoV-2 is associated with changes in brain structure in UK Biobank

There is strong evidence of brain-related abnormalities in COVID-191–13. However, it remains unknown whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here we investigated brain changes in 785 participants of UK Biobank (aged 51–81 years) who were imaged twice using magnetic resonance imaging, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans—with 141 days on average separating their diagnosis and the second scan—as well as 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including (1) a greater reduction in grey matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus; (2) greater changes in markers of tissue damage in regions that are functionally connected to the primary olfactory cortex; and (3) a greater reduction in global brain size in the SARS-CoV-2 cases. The participants who were infected with SARS-CoV-2 also showed on average a greater cognitive decline between the two time points. Importantly, these imaging and cognitive longitudinal effects were still observed after excluding the 15 patients who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease through olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious effect can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow-up.

SARS-CoV-2 is associated with changes in brain structure in UK Biobank

There is strong evidence of brain-related abnormalities in COVID-191-13. However, it remains unknown whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here we investigated brain changes in 785 participants of UK Biobank (aged 51-81 years) who were imaged twice using magnetic resonance imaging, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans-with 141 days on average separating their diagnosis and the second scan-as well as 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including (1) a greater reduction in grey matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus; (2) greater changes in markers of tissue damage in regions that are functionally connected to the primary olfactory cortex; and (3) a greater reduction in global brain size in the SARS-CoV-2 cases. The participants who were infected with SARS-CoV-2 also showed on average a greater cognitive decline between the two time points. Importantly, these imaging and cognitive longitudinal effects were still observed after excluding the 15 patients who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease through olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious effect can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow-up.

SARS-CoV-2 is associated with changes in brain structure in UK Biobank

There is strong evidence for brain-related abnormalities in COVID-19 1-13 . It remains unknown however whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here, we investigated brain changes in 785 UK Biobank participants (aged 51-81) imaged twice, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans, with 141 days on average separating their diagnosis and second scan, and 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including: (i) greater reduction in grey matter thickness and tissue-contrast in the orbitofrontal cortex and parahippocampal gyrus, (ii) greater changes in markers of tissue damage in regions functionally-connected to the primary olfactory cortex, and (iii) greater reduction in global brain size. The infected participants also showed on average larger cognitive decline between the two timepoints. Importantly, these imaging and cognitive longitudinal effects were still seen after excluding the 15 cases who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease via olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious impact can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow up.

Healthcare policy by other means: Cancer clinical research as "oncopolicy"

Social studies of biomedicine often focus on how exogenous policies shape the medical domain. While policy agendas no doubt affect complex biomedical projects, in the present paper we analyze a different dynamic, namely how oncologists enact policy as part of several flagship precision oncology endeavors. Empirically, the article focuses on the U.S. TAPUR trial, the Dutch DRUP trial, and the Canadian CAPTUR trial, which have recently been joined by similar Scandinavian studies. Taken together, these trials represent innovative forms of clinical research that, beyond their varying experimental nature, have been designed to transform the evidential processes to provide access to biomarker-driven treatments. Along with gathering evidence on effectiveness of off-label targeted therapies, their explicit goals include the recentering of a major professional organization around research, and the reframing of healthcare as a learning system seamlessly connecting epistemic, organizational, and economic issues. Accordingly, we analyze the design and implementation of these trials as a form of (onco)policy by other means.

Multi-polar scripts: Techno-regulatory environments and the rise of precision oncology diagnostic tests

The paper examines the development and marketing of five multi-gene tests, a.k.a. as tumor signatures, designed to aid clinicians and cancer patients in therapeutic decision-making, and, in particular, to avoid overtreatment. We build on a 2011 paper that investigated the emergence of this new domain by opening the 'black box' of two pioneering tests and analyzing the hybrid, scientific-regulatory 'scripts' that were built into them. In subsequent years, second-generation tests, produced by a diverse blend of academic and commercial initiatives, have become available, and they all built into their scripts the lessons learned from their predecessors. The present paper confirms the heuristic value of the initial script-analysis but expands it to consider the multi-polar nature of the space within which multigene tests mutually position themselves. We examine how the tests were first problematized - i.e. how they described and prescribed the kind of world in which they would operate - and how their initial problematization was re-specified following the emergence of a comparative arena and their resulting informational enrichment. In parallel, we explore valuation processes, i.e. the evolving definition of the set of referents against which the assays are mutually compared, and the debates about the appropriate criteria for doing so. We note that the cancer diagnostic industry is involved in the reconfiguration of the multi-polar environment defined by socio-technical, techno-scientific, and regulatory matters of concern that seamlessly blend commercial and scientific considerations.

Correction to: Informing materials: drugs as tools for exploring cancer mechanisms and pathways

The original version of this article unfortunately contained a mistake. Three entries are incorrect in the reference list. The corrected references are given below.

Suppression of tumor-derived Semaphorin 7A and genetic ablation of host-derived Semaphorin 7A impairs tumor progression in a murine model of advanced breast carcinoma

Solid tumors can generate a plethora of neurogenesis-related molecules that enhance their growth and metastasis. Among them, we have identified axonal guidance molecule Semaphorin 7A (SEMA7A) in breast cancer. The goal of this study was to determine the therapeutic effect of suppressing SEMA7A levels in the 4T1 murine model of advanced breast carcinoma. We used anti-SEMA7A short hairpin RNA (shRNA) to gene silence SEMA7A in 4T1 mammary tumor cells. When implanted into the mammary fat pads of syngeneic mice, SEMA7A shRNA-expressing 4T1 tumors exhibited decreased growth rates, deferred metastasis and reduced mortality. In vitro, SEMA7A shRNA-expressing 4T1 cells had weakened proliferative, migratory and invasive abilities, and decreased levels of mesenchymal factors. Atomic force microscopy studies showed that SEMA7A shRNA-expressing 4T1 cells had an increase in cell stiffness that corresponded with their decreased malignant potential. Genetic ablation of host-derived SEMA7A further enhanced the antitumor effects of SEMA7A shRNA gene silencing in 4T1 cells. Our preclinical findings demonstrate a critical role for SEMA7A in mediating mammary tumor progression.

Thalamic input to auditory cortex is locally heterogeneous but globally tonotopic

Topographic representation of the receptor surface is a fundamental feature of sensory cortical organization. This is imparted by the thalamus, which relays information from the periphery to the cortex. To better understand the rules governing thalamocortical connectivity and the origin of cortical maps, we used in vivo two-photon calcium imaging to characterize the properties of thalamic axons innervating different layers of mouse auditory cortex. Although tonotopically organized at a global level, we found that the frequency selectivity of individual thalamocortical axons is surprisingly heterogeneous, even in layers 3b/4 of the primary cortical areas, where the thalamic input is dominated by the lemniscal projection. We also show that thalamocortical input to layer 1 includes collaterals from axons innervating layers 3b/4 and is largely in register with the main input targeting those layers. Such locally varied thalamocortical projections may be useful in enabling rapid contextual modulation of cortical frequency representations.

HMGCR-associated myositis: a New Zealand case series and estimate of incidence

Statins are one of the most commonly prescribed drugs in New Zealand, with 525 772 or 16.5% of the adult New Zealand population prescribed a statin between June 2013 and July 2014. While generally well-tolerated, statins are known to cause a range of muscle-related side effects, ranging from myalgia to life-threatening rhabdomyolysis. Recently, it has been recognised that in rare instances, statins can induce an immune-mediated necrotising myositis with antibodies against 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), the enzymatic target of statins. In 2014, anti-HMGCR antibody testing was introduced to Canterbury Health Laboratories (CHL), with this being the only laboratory in New Zealand performing this test during the period of this case series. This article describes an index case and characterises the clinical features of a subsequent 12-month series. From this series, we estimated the yearly incidence of HMGCR-associated myositis at 1.7/million/year or ~1/90 000 New Zealand statin users.

Informing materials: drugs as tools for exploring cancer mechanisms and pathways

This paper builds on previous work that investigated anticancer drugs as 'informed materials', i.e., substances that undergo an informational enrichment that situates them in a dense relational web of qualifications and measurements generated by clinical experiments and clinical trials. The paper analyzes the recent transformation of anticancer drugs from 'informed' to 'informing material'. Briefly put: in the post-genomic era, anti-cancer drugs have become instruments for the production of new biological, pathological, and therapeutic insights into the underlying etiology and evolution of cancer. Genomic platforms characterize individual patients' tumors based on their mutational landscapes. As part of this new approach, drugs targeting specific mutations transcend informational enrichment to become tools for informing (and destabilizing) their targets, while also problematizing the very notion of a 'target'. In other words, they have become tools for the exploration of cancer pathways and mechanisms. While several studies in the philosophy and history of biomedicine have called attention to the heuristic relevance and experimental use of drugs, few have investigated concrete instances of this role of drugs in clinical research.

"Triple negative breast cancer": Translational research and the (re)assembling of diseases in post-genomic medicine

The paper examines the debate about the nature and status of "Triple-negative breast cancer", a controversial biomedical entity whose existence illustrates a number of features of post-genomic translational research. The emergence of TNBC is intimately linked to the rise of molecular oncology, and, more generally, to the changing configuration of the life sciences at the turn of the new century. An unprecedented degree of integration of biological and clinical practices has led to the proliferation of bio-clinical entities emerging from translational research. These translations take place between platforms rather than between clinical and laboratory settings. The complexity and heterogeneity of TNBC, its epistemic and technical, biological and clinical dualities, result from its multiple instantiations via different platforms, and from the uneven distribution of biological materials, techniques, and objects across clinical research settings. The fact that TNBC comes in multiple forms, some of which seem to be incompatible or, at least, only partially overlapping, appears to be less a threat to the whole endeavor, than an aspect of an ongoing translational research project. Discussions of translational research that rest on a distinction between basic research and its applications fail to capture the dynamics of this new domain of activity, insofar as application is built-in from the very beginning in the bio-clinical entities that emerge from the translational research domain.

Comparing hospital and telephone follow-up for patients treated for stage-I endometrial cancer (ENDCAT trial): a randomised, multicentre, non-inferiority trial

OBJECTIVE

To evaluate the effectiveness of nurse-led telephone follow-up (TFU) for patients with stage-I endometrial cancer.

DESIGN

Multicentre, randomised, non-inferiority trial.

SETTING

Five centres in the North West of England.

SAMPLE

A cohort of 259 women treated for stage-I endometrial cancer attending hospital outpatient clinics for routine follow-up.

METHODS

Participants were randomly allocated to receive traditional hospital based follow-up (HFU) or nurse-led TFU.

MAIN OUTCOME MEASURES

Primary outcomes were psychological morbidity (State Trait Anxiety Inventory, STAI-S) and patient satisfaction with the information provided. Secondary outcomes included patient satisfaction with service, quality of life, and time to detection of recurrence.

RESULTS

The STAI-S scores post-randomisation were similar between groups [mean (SD): TFU 33.0 (11.0); HFU 35.5 (13.0)]. The estimated between-group difference in STAI-S was 0.7 (95% confidence interval, 95% CI -1.9 to 3.3); the confidence interval lies above the non-inferiority limit (-3.5), indicating the non-inferiority of TFU. There was no significant difference between groups in reported satisfaction with information (odds ratio, OR 0.9; 95% CI 0.4-2.1; P = 0.83). Women in the HFU group were more likely to report being kept waiting for their appointment (P = 0.001), that they did not need any information (P = 0.003), and were less likely to report that the nurse knew about their particular case and situation (P = 0.005).

CONCLUSIONS

The TFU provides an effective alternative to HFU for patients with stage-I endometrial cancer, with no reported physical or psychological detriment. Patient satisfaction with information was high, with similar levels between groups.

TWEETABLE ABSTRACT

ENDCAT trial shows effectiveness of nurse-led telephone follow-up for patients with stage-I endometrial cancer.

Behavioral training promotes multiple adaptive processes following acute hearing loss

The brain possesses a remarkable capacity to compensate for changes in inputs resulting from a range of sensory impairments. Developmental studies of sound localization have shown that adaptation to asymmetric hearing loss can be achieved either by reinterpreting altered spatial cues or by relying more on those cues that remain intact. Adaptation to monaural deprivation in adulthood is also possible, but appears to lack such flexibility. Here we show, however, that appropriate behavioral training enables monaurally-deprived adult humans to exploit both of these adaptive processes. Moreover, cortical recordings in ferrets reared with asymmetric hearing loss suggest that these forms of plasticity have distinct neural substrates. An ability to adapt to asymmetric hearing loss using multiple adaptive processes is therefore shared by different species and may persist throughout the lifespan. This highlights the fundamental flexibility of neural systems, and may also point toward novel therapeutic strategies for treating sensory disorders.

DOI:http://dx.doi.org/10.7554/eLife.12264.001

The brain normally compares the timing and intensity of the sounds that reach each ear to work out a sound’s origin. Hearing loss in one ear disrupts these between-ear comparisons, which causes listeners to make errors in this process. With time, however, the brain adapts to this hearing loss and once again learns to localize sounds accurately.

Previous research has shown that young ferrets can adapt to hearing loss in one ear in two distinct ways. The ferrets either learn to remap the altered between-ear comparisons, caused by losing hearing in one ear, onto their new locations. Alternatively, the ferrets learn to locate sounds using only their good ear. Each strategy is suited to localizing different types of sound, but it was not known how this adaptive flexibility unfolds over time, whether it persists throughout the lifespan, or whether it is shared by other species.

Now, Keating et al. show that, with some coaching, adult humans also adapt to temporary loss of hearing in one ear using the same two strategies. In the experiments, adult humans were trained to localize different kinds of sounds while wearing an earplug in one ear. These sounds were presented from 12 loudspeakers arranged in a horizontal circle around the person being tested. The experiments showed that short periods of behavioral training enable adult humans to adapt to a hearing loss in one ear and recover their ability to localize sounds.

Just like the ferrets, adult humans learned to correctly associate altered between-ear comparisons with their new locations and to rely more on the cues from the unplugged ear to locate sound. Which of these adaptive strategies the participants used depended on the frequencies present in the sounds. The cells in the ear and brain that detect and make sense of sound typically respond best to a limited range of frequencies, and so this suggests that each strategy relies on a distinct set of cells. Keating et al. confirmed in ferrets that different brain cells are indeed used to bring about adaptation to hearing loss in one ear using each strategy. These insights may aid the development of new therapies to treat hearing loss.

DOI:http://dx.doi.org/10.7554/eLife.12264.002

Testing devices or experimental systems? Cancer clinical trials take the genomic turn

Clinical trials are often described as machine-like systems for generating specific information concerning drug safety and efficacy, and are understood as a component of the industrial drug development processes. This paper argues that contemporary clinical trials in oncology are not reducible to mere drug testing. Drawing on ethnographic fieldwork and interviews with researchers in the field of oncology from 2010 to 2013, we introduce a conceptual contrast between trials as testing machines and trials as clinical experimental systems to draw attention to the ways trials are increasingly being used to ask open-ended scientific questions. When viewed as testing machines, clinical trials are seen as a means to produce answers to straightforward questions and deviations from the protocol are seen as bugs in the system; but practitioners can also treat trials as clinical experimental systems to investigate as yet undefined problems and where heterogeneity becomes a means to produce novel biological or clinical insights. The rise of "biomarker-driven" clinical trials in oncology, which link measurable biological characteristics such as genetic mutations to clinical features such as a patient's response to a particular drug, exemplifies a trend towards more experimental styles of clinical work. These transformations are congruent with changes in the institutional structure of clinical research in oncology, including a movement towards more flexible, networked research arrangements, and towards using individual patients as model systems for asking biological questions.

Behavioural sensitivity to binaural spatial cues in ferrets: evidence for plasticity in the duplex theory of sound localization

For over a century, the duplex theory has guided our understanding of human sound localization in the horizontal plane. According to this theory, the auditory system uses interaural time differences (ITDs) and interaural level differences (ILDs) to localize low-frequency and high-frequency sounds, respectively. Whilst this theory successfully accounts for the localization of tones by humans, some species show very different behaviour. Ferrets are widely used for studying both clinical and fundamental aspects of spatial hearing, but it is not known whether the duplex theory applies to this species or, if so, to what extent the frequency range over which each binaural cue is used depends on acoustical or neurophysiological factors. To address these issues, we trained ferrets to lateralize tones presented over earphones and found that the frequency dependence of ITD and ILD sensitivity broadly paralleled that observed in humans. Compared with humans, however, the transition between ITD and ILD sensitivity was shifted toward higher frequencies. We found that the frequency dependence of ITD sensitivity in ferrets can partially be accounted for by acoustical factors, although neurophysiological mechanisms are also likely to be involved. Moreover, we show that binaural cue sensitivity can be shaped by experience, as training ferrets on a 1-kHz ILD task resulted in significant improvements in thresholds that were specific to the trained cue and frequency. Our results provide new insights into the factors limiting the use of different sound localization cues and highlight the importance of sensory experience in shaping the underlying neural mechanisms.

Developmental plasticity of spatial hearing following asymmetric hearing loss: context-dependent cue integration and its clinical implications

Under normal hearing conditions, comparisons of the sounds reaching each ear are critical for accurate sound localization. Asymmetric hearing loss should therefore degrade spatial hearing and has become an important experimental tool for probing the plasticity of the auditory system, both during development and adulthood. In clinical populations, hearing loss affecting one ear more than the other is commonly associated with otitis media with effusion, a disorder experienced by approximately 80% of children before the age of two. Asymmetric hearing may also arise in other clinical situations, such as after unilateral cochlear implantation. Here, we consider the role played by spatial cue integration in sound localization under normal acoustical conditions. We then review evidence for adaptive changes in spatial hearing following a developmental hearing loss in one ear, and show that adaptation may be achieved either by learning a new relationship between the altered cues and directions in space or by changing the way different cues are integrated in the brain. We next consider developmental plasticity as a source of vulnerability, describing maladaptive effects of asymmetric hearing loss that persist even when normal hearing is provided. We also examine the extent to which the consequences of asymmetric hearing loss depend upon its timing and duration. Although much of the experimental literature has focused on the effects of a stable unilateral hearing loss, some of the most common hearing impairments experienced by children tend to fluctuate over time. We therefore propose that there is a need to bridge this gap by investigating the effects of recurring hearing loss during development, and outline recent steps in this direction. We conclude by arguing that this work points toward a more nuanced view of developmental plasticity, in which plasticity may be selectively expressed in response to specific sensory contexts, and consider the clinical implications of this.

Context-specific reweighting of auditory spatial cues following altered experience during development

Background

Neural systems must weight and integrate different sensory cues in order to make decisions. However, environmental conditions often change over time, altering the reliability of different cues and therefore the optimal way for combining them. To explore how cue integration develops in dynamic environments, we examined the effects on auditory spatial processing of rearing ferrets with localization cues that were modified via a unilateral earplug, interspersed with brief periods of normal hearing.

Results

In contrast with control animals, which rely primarily on timing and intensity differences between their two ears to localize sound sources, the juvenile-plugged ferrets developed the ability to localize sounds accurately by relying more on the unchanged spectral localization cues provided by the single normal ear. This adaptive process was paralleled by changes in neuronal responses in the primary auditory cortex, which became relatively more sensitive to these monaural spatial cues. Our behavioral and physiological data demonstrated, however, that the reweighting of different spatial cues disappeared as soon as normal hearing was experienced, showing for the first time that this type of plasticity can be context specific.

Conclusions

These results show that developmental changes can be selectively expressed in response to specific acoustic conditions. In this way, the auditory system can develop and simultaneously maintain two distinct models of auditory space and switch between these models depending on the prevailing sensory context. This ability is likely to be critical for maintaining accurate perception in dynamic environments and may point toward novel therapeutic strategies for individuals who experience sensory deficits during development.

•

Ferrets reared with a unilateral hearing loss are able to localize sounds accurately

•

Adaptation relies on cue reweighting that reverses when normal hearing is available

•

Auditory cortical neurons show corresponding context-specific plasticity

•

Contextual cue reweighting maintains perceptual stability in dynamic environments

Therapy's Shadow: A Short History of the Study of Resistance to Cancer Chemotherapy

This article traces the history of research on resistance to drug therapy in oncology using scientometric techniques and qualitative analysis. Using co-citation analysis, we generate maps to visualize subdomains in resistance research in two time periods, 1975–1990 and 1995–2010. These maps reveal two historical trends in resistance research: first, a shift in focus from generic mechanisms of resistance to chemotherapy to a focus on resistance to targeted therapies and molecular mechanisms of oncogenesis; and second, a movement away from an almost exclusive reliance on animal and cell models and toward the generation of knowledge about resistance through clinical trial work. A close reading of highly cited articles within each subdomain cluster reveals specific points of transition from one regime to the other, in particular the failure of several promising theories of resistance to be translated into clinical insights and the emergence of interest in resistance to a new generation of targeted agents such as imatinib and trastuzumab. We argue that the study of resistance in the oncology field has thus become more integrated with research into cancer therapy – rather than constituting it as a separate domain of study, as it has done in the past, contemporary research treats resistance as the flip side to treatment, as therapy’s shadow.

Neural circuits underlying adaptation and learning in the perception of auditory space

Sound localization mechanisms are particularly plastic during development, when the monaural and binaural acoustic cues that form the basis for spatial hearing change in value as the body grows. Recent studies have shown that the mature brain retains a surprising capacity to relearn to localize sound in the presence of substantially altered auditory spatial cues. In addition to the long-lasting changes that result from learning, behavioral and electrophysiological studies have demonstrated that auditory spatial processing can undergo rapid adjustments in response to changes in the statistics of recent stimulation, which help to maintain sensitivity over the range where most stimulus values occur. Through a combination of recording studies and methods for selectively manipulating the activity of specific neuronal populations, progress is now being made in identifying the cortical and subcortical circuits in the brain that are responsible for the dynamic coding of auditory spatial information.

Cancer clinical trials in the era of genomic signatures: biomedical innovation, clinical utility, and regulatory-scientific hybrids

The paper examines two large-scale, North American and European clinical trials designed to validate two commercially available genomic tumor signatures that predict a patient's risk of breast cancer recurrence and response to chemotherapy. The paper builds on empirical evidence from the two trials to explore the emergence of diverse regulatory-scientific hybrids; that is, the paper discusses configurations of genomic practice and bioclinical work that depend on linkages between technical, commercial, patient, clinical, and legal interests and institutions. The development of the genomic signatures for each trial--Oncotype DX and MammaPrint--has followed quite different routes. Oncotype began as a commercial platform: the company that produced it did not discover a signature but rather constructed it by asking users at every step what clinical question they wanted the signature to answer and what data would be credible in that regard. The test has been designed to minimally disrupt existing clinical workflows. MammaPrint, on the other hand, began as a breast cancer signature: the researchers who discovered it, at the Netherlands Cancer Institute (NKI), established a company to commercialize it as a test after the fact. MammaPrint requires a change in pathologists' routines. Thus, while these two trials signify a new departure for clinical cancer trials on a number of levels--they both incorporate new models of interaction between biotech companies and public research, and they both aim to establish the clinical relevance of genomic markers--they also embody different socio-technical scripts: one attempts to accommodate established routines, while the other openly challenges prevailing evidential hierarchies and existing biomedical configurations.

Adaptation to stimulus statistics in the perception and neural representation of auditory space

Sensory systems are known to adapt their coding strategies to the statistics of their environment, but little is still known about the perceptual implications of such adjustments. We investigated how auditory spatial processing adapts to stimulus statistics by presenting human listeners and anesthetized ferrets with noise sequences in which interaural level differences (ILD) rapidly fluctuated according to a Gaussian distribution. The mean of the distribution biased the perceived laterality of a subsequent stimulus, whereas the distribution's variance changed the listeners' spatial sensitivity. The responses of neurons in the inferior colliculus changed in line with these perceptual phenomena. Their ILD preference adjusted to match the stimulus distribution mean, resulting in large shifts in rate-ILD functions, while their gain adapted to the stimulus variance, producing pronounced changes in neural sensitivity. Our findings suggest that processing of auditory space is geared toward emphasizing relative spatial differences rather than the accurate representation of absolute position.

Chronic detachable headphones for acoustic stimulation in freely moving animals

A growing number of studies of auditory processing are being carried out in awake, behaving animals, creating a need for precisely controlled sound delivery without restricting head movements. We have designed a system for closed-field stimulus presentation in freely moving ferrets, which comprises lightweight, adjustable headphones that can be consistently positioned over the ears via a small, skull-mounted implant. The invasiveness of the implant was minimized by simplifying its construction and using dental adhesive only for attaching it to the skull, thereby reducing the surgery required and avoiding the use of screws or other anchoring devices. Attaching the headphones to a chronic implant also reduced the amount of contact they had with the head and ears, increasing the willingness of the animals to wear them. We validated sound stimulation via the headphones in ferrets trained previously in a free-field task to localize stimuli presented from one of two loudspeakers. Noise bursts were delivered binaurally over the headphones and interaural level differences (ILDs) were introduced to allow the sound to be lateralized. Animals rapidly transferred from the free-field task to indicate the perceived location of the stimulus presented over headphones. They showed near perfect lateralization with a 5 dB ILD, matching the scores achieved in the free-field task. As expected, the ferrets' performance declined when the ILD was reduced in value. This closed-field system can easily be adapted for use in other species, and provides a reliable means of presenting closed-field stimuli whilst monitoring behavioral responses in freely moving animals.

Who's minding the data? Data Monitoring Committees in clinical cancer trials

Modern biomedicine is based on a number of novel institutions and practices that, in order to function, require some degree of formal and informal regulation. This paper contributes to the ongoing investigation of these processes, and the forms of objectivity they generate, by examining the emergence, development and deployment of Data Monitoring Committees in the field of clinical trials. The idea of a DMC had originally been raised in the clinical trial methodology literature in the 1970s so as to solve the problem of the management of interim trial data. Many leading clinical trial statisticians proposed that interim data and analyses be restricted to members of a DMC. Since the late 1980s, DMCs have evolved considerably in a constant search for ethical neutrality and objectivity through the use of sophisticated statistical techniques and novel organisational strategies. They have also been beset by a fundamental tension as to who or what should count as objective in such an undertaking. The paper examines the evolution of this institution in terms of the techniques brought to bear on the issues that they are expected to solve, the organisational forms through which DMCs have evolved and the ideals of objectivity that these forms embody.

Phages, antibodies and de-monstration

Using examples from the field of molecular genetics and immunology, this paper examines the argumentative strategy underlying the use of electron micrographs as decisive evidence for previously uncertain or disputed claims. Scientists often resort to visual imagery in order to demonstrate the factual status of their claims and thus to compel assent from their peers, therefore bypassing other forms of argumentation such as propositional reasoning. The particular form of demonstration discussed in this article resorts to the use of photography rather than drawings and diagrams. While the mechanical objectivity of micrographs certainly adds to their evidential strength, the pictures we examine derive part of their power from their arrangement in a sequence that mimics experimental operations. The visual argument tracks the textual report of the steps in a biochemical or molecular genetic experiment, with which it becomes intimately associated. We conclude that much of the evidential strength conveyed by the articles we analyze is to be sought less in the extrinsic attributes of the instrumentation they mobilized than in the specific material and argumentative practices enacted by those particular uses of the instrument.

The emergence of clinical practice guidelines

Clinical practice guidelines are now ubiquitous. This article describes the emergence of such guidelines in a way that differs from the two dominant explanations, one focusing on administrative cost-cutting and the other on the need to protect collective professional autonomy. Instead, this article argues that the spread of guidelines represents a new regulation of medical care resulting from a confluence of circumstances that mobilized many different groups. Although the regulation of quality has traditionally been based on the standardization of professional credentials, since the 1960s it has intensified and been supplemented by efforts to standardize the use of medical procedures. This shift is related to the spread of standardization within medicine and especially in research, public health, and large bureaucratic health care organizations.

A case of torted parafimbrial cyst on MRI: case report and review of the literature

Para-ovarian cysts (POCs) are an occasional finding at surgery, although they are rarely appreciated on imaging studies. Accurate diagnosis depends upon the demonstration of a para-ovarian location. We present the MR appearances of a torted POC in a fimbrial location, resembling a dermoid cyst.

Cancer clinical trials: the emergence and development of a new style of practice

Clinical trials are the principal vector for the development of chemotherapy, and they have become such a pervasive element of clinical cancer research that modern oncologists tend to take them for granted. Yet the system of cancer clinical trials amounts to a relatively recent (post-World War II) innovation. Its development has proceeded through ad hoc adjustments, and has produced a self-vindicating, yet open-ended, style of practice. This paper examines the historical development and articulation of the components of this new style of practice (protocols, oncologists, statistics, patients, and diseases), and of the new kind of objectivity they engender, by drawing on selected examples from American and European cancer clinical trial systems.

Mapping the emergence and development of translational cancer research

Cancer research is one of the principal targets of translational research, yet the nature of the relationships between different forms of cancer research remains controversial. The paper examines publications in the cancer field during the 1980-2000 period. A network analysis software program was used to map evolving patterns of inter-citations between cancer publications, their different research levels and the transformation of their relational content. Both inter-citation and content maps provide striking evidence of the consolidation in the 1990s of a translational interface that was practically non existent a few decades before. In 1980, research was polarized according to the allegiance to either a clinical or a laboratory style. This same duality obtains in the year 2000, albeit with the additional presence of a third, biomedical player whose activities are similarly structured by a common orientation, rather than by an exclusive commitment to a specific sub-domain.

Regulatory objectivity and the generation and management of evidence in medicine

The evolution of Western medicine since World War II has resulted in the emergence of new practices based on the direct interaction of biology and medicine. The post-war realignment of biology and medicine has been accompanied by the emergence of a new type of objectivity, regulatory objectivity, that is based on the systematic recourse to the collective production of evidence. Unlike forms of objectivity that emerged in earlier eras, regulatory objectivity consistently results in the production of conventions, sometimes tacit and unintentional but most often arrived at through concerted programs of action. These actions incorporate unprecedented levels of reflexivity, in the sense that biomedical practitioners in their debates and discussions take into account the conventional dimension of their endeavors. The conventions produced by regulatory objectivity create the conditions for a clinical objectivity that relies on the existence of entities and protocols produced and maintained far outside the intimate encounter between doctor and patient. By establishing endogenous forms of regulation, regulatory objectivity operates on a different plane and in a different mode from those suggested by analysts who treat all regulation as a form of rationalization imposed upon medicine from without.

[What is biomedicine? A socio-historical outline]

The article examines the debates surrounding the emergence of the term biomedicine, with a particular focus on the relation between the pathological and the normal. The authors reject simplistic definitions of biomedicine as a one-way street leading to the application of medical knowledge to medicine, or even as a two-way street characterized by iterative exchanges between the clinic and the laboratory. Rather, the authors introduce the notion of a biomedical platform as the site where the clinic and the laboratory intermingle and are realigned in connection with the ongoing process of medical innovation and the increasing automation of molecular procedures. The examples used in the article are drawn mainly from the field of onco-hematology.

Does biomedicine entail the successful reduction of pathology to biology?

The idea of reducing pathology to biology has an extensive history, and the initial forms of the enterprise were unsuccessful. This article discusses the philosophical literature surrounding the notion of reduction in the sciences in general and of biology in particular; reviews several 19th-century programs that promoted the reduction of medicine to other biological disciplines; and examines the post-war origins of the notion of biomedicine. It shows how biology and medicine tend to interact in the constitution of new biomedical knowledge and how the notion of a pathological process resulting in a lesion remains central to the understanding of disease. The article proposes that while strict reduction has yet to be realized, one can speak of a continuing and successful realignment of biology and pathology since the Second World War.

From screening to clinical research: the cure of leukemia and the early development of the cooperative oncology groups, 1955-1966

Recent work in the history and sociology of biomedicine has emphasized the novelty of the biomedical enterprise as a distinctive institutional, material, and epistemological configuration. Since World War II, biology and medicine have become such tightly intertwined research enterprises that those working in biomedicine cannot predict whether a particular research project, clinical investigation, or even clinical intervention will result in biological or medical facts. In this paper, we examine part of the process of the emergence of biomedicine by focusing on the development of clinical cancer trials in the United States in the years 1955-66, a period during which the clinical trials program run by the National Cancer Institute became autonomous from the Institute's screening program for anticancer compounds. We examine in particular the work carried out by the cooperative groups and the Acute Leukemia Task Force to which they belonged, analyzing the evolution of the relations between screening, chemotherapy, clinical trials, and clinical research.

Oral antibodies to human papillomavirus type 16 in women with cervical neoplasia

This study investigated the relationship between human papillomavirus type 16 (HPV-16) antibodies detected in oral fluid from women with cervical neoplasia, their HPV-16 antibody seroprevalence, and their cervical HPV-16 DNA presence. Cervical HPV-16 DNA was detected by polymerase chain reaction in 43.2% (35/81) of these women. The prevalence of IgG and IgA antibodies to HPV-16 virus-like particles (VLP-16) in oral fluid and was investigated by enzyme-linked immunosorbent assay. Anti-VLP-16 IgA antibodies were detected in oral fluid from 54.3% (44/81) of women with cervical neoplasia, compared with 8% (3/36) in controls (P = 0.000002). Anti-VLP-16 IgG was detected in oral fluid from 43.2.9% (25/72) and 13.3% (4/30; P = 0.029), respectively. Women who were HPV-16 DNA positive at their cervical lesion, displayed an oral fluid anti-VLP-16 IgA prevalence of 60.7% (17/28) and HPV-16 DNA negative women an oral fluid anti-VLP-16 IgA prevalence of 50% (20/40; P = 0.38). Oral fluid anti-VLP-16 IgG prevalence in HPV-16 DNA positive women was 28.6% (8/28) compared with 40% (16/40) in oral fluid from HPV-16 DNA negative women (P = 0.3). Amongst HPV-16 DNA positive women, the anti-VLP-16 IgG seroprevalence was 75% (21/28) and IgA seroprevalence 35.7% (10/28) and for the HPV-16 DNA negative women these values were 60% (24/40) and 32.5% (13/40), respectively. Oral IgA antibody testing proved no more sensitive than serum antibody detection for the determination of HPV infection but could be useful as a non-invasive screening method for women with cervical neoplasia and for estimating the mucosal antibody response to HPV vaccines.

Tricuspid atresia--profile and outcome

Tricuspid atresia (TA) is the third most common cyanotic congenital cardiac lesion, with a mortality rate of 90% before the age of 10 years. Surgical intervention has reduced the mortality, but with unfavourable anatomy the mortality remains high. The aim of this study was to look at the profile of a cohort of children with TA and to evaluate treatment modalities and outcome. Twenty-seven children were included in this retrospective descriptive study. Twenty-three were referred with central cyanosis and 25% with cardiac failure. All patients had a left superior QRS axis on electrocardiogram (ECG). Eleven patients died, 8 before surgical intervention and 3 postoperatively. Outcome was mainly influenced by the anatomy of the pulmonary arteries especially when the pulmonary arteries were extremely hypoplastic. Patients with increased pulmonary blood flow did better than those with decreased pulmonary blood flow. There was a statistically significant difference in survival between the surgical and non-surgical groups. Few of our patients qualified for the Fontan procedure mainly because of increased pulmonary pressures in the high pulmonary blood flow group and severe hypoplastic pulmonary arteries in the low pulmonary blood flow group. Early referral is essential for palliation so that more definitive surgery can be done to achieve better results.

Language deficits in dyslexic children: speech perception, phonology, and morphology

We investigated the relationship between dyslexia and three aspects of language: speech perception, phonology, and morphology. Reading and language tasks were administered to dyslexics aged 8-9 years and to two normal reader groups (age-matched and reading-level matched). Three dyslexic groups were identified: phonological dyslexics (PD), developmentally language impaired (LI), and globally delayed (delay-type dyslexics). The LI and PD groups exhibited similar patterns of reading impairment, attributed to low phonological skills. However, only the LI group showed clear speech perception deficits, suggesting that such deficits affect only a subset of dyslexics. Results also indicated phonological impairments in children whose speech perception was normal. Both the LI and the PD groups showed inflectional morphology difficulties, with the impairment being more severe in the LI group. The delay group's reading and language skills closely matched those of younger normal readers, suggesting these children had a general delay in reading and language skills, rather than a specific phonological impairment. The results are discussed in terms of models of word recognition and dyslexia.

Are speech perception deficits associated with developmental dyslexia?

Phonological awareness and phoneme identification tasks were administered to dyslexic children and both chronological age (CA) and reading-level (RL) comparison groups. Dyslexic children showed less sharply defined categorical perception of a bath-path continuum varying voice onset time when compared to the CA but not the RL group. The dyslexic children were divided into two subgroups based on phoneme awareness. Dyslexics with low phonemic awareness made poorer /b/-/p/ distinctions than both CA and RL groups, but dyslexics with normal phonemic awareness did not. Examination of individual profiles revealed that the majority of subjects in each group exhibited normal categorical perception. However, 7 of 25 dyslexics had abnormal identification functions, compared to 1 subject in the CA group and 3 in the RL group. The results suggest that some dyslexic children have a perceptual deficit that may interfere with processing of phonological information. Speech perception difficulties may also be partially related to reading experience.