Growth and development of oncology nursing in North America

The specialty of oncology nursing has been evolving in North America for nearly a century, keeping pace with the rapid and dynamic developments in cancer care. This narrative review outlines the history and development of oncology nursing in North America with a focus on the United States and Canada. The review highlights the important contributions that specialized oncology nurses have made to the care of people affected by cancer from time of diagnosis through treatment, follow-up and survivorship care, as well as palliative, end-of-life, and bereavement care. Keeping pace with the rapid evolution of cancer treatments throughout the last century, nursing roles have similarly evolved to meet the need for more specialized training and education. This paper discusses the growth of nursing roles, including advanced practice and navigator roles. In addition, the paper outlines the development of professional oncology nursing organizations and societies that have been established to help guide the profession with best practices, standards, and competencies. Finally, the paper discusses new challenges and opportunities regarding the access, availability, and delivery of cancer care that will shape future development of the specialty. Oncology nurses will continue to be integral to the provision of high-quality, comprehensive cancer care as clinicians, educators, researchers, and leaders.

Integrating Palliative Care in Hematopoietic Stem Cell Transplantation: A Qualitative Study Exploring Patient, Caregiver, and Clinician Perspectives

PURPOSE

To explore patient, caregiver, and clinician perspectives on palliative care for patients undergoing hematopoietic stem cell transplantation (HSCT).

PARTICIPANTS & SETTING

8 patients who had undergone or would undergo HSCT, 4 caregivers, and 16 HSCT clinicians.

METHODOLOGIC APPROACH

This qualitative, interpretive descriptive study used semistructured interviews conducted via telephone or videoconference.

FINDINGS

Responses were categorized into the following two themes: concerns and challenges during and after HSCT, and tensions with integrating palliative care into HSCT.

IMPLICATIONS FOR NURSING

The findings from this study highlight the unique and varied needs of patients and their caregivers during and after HSCT. More research is required to determine how to best integrate palliative care in this setting.

« Comment en parler? »: Création d’une simulation virtuelle sur les soins de santé sexuelle destinés aux survivantes du cancer du sein

La simulation virtuelle (SV) est une stratégie innovante et proactive d’application pratique de la théorie qui peut améliorer les connaissances et le savoir-faire des professionnels de la santé. Toutefois, aucun article n’a été publié à ce jour sur l’utilisation de la simulation pour améliorer les soins aux survivants du cancer. Le présent article décrit notre expérience de création d’une SV pour former les professionnels de la santé aux problèmes sexuels vécus par les femmes traitées pour un cancer du sein. Si on extrapole à partir des recherches effectuées dans d’autres contextes, la SV permettrait de bonifier les connaissances et compétences dont les professionnels ont besoin pour accompagner les survivantes ayant des préoccupations de nature sexuelle. Notre expérience de développement de SV pourra motiver et guider d’autres chercheurs qui souhaitent eux aussi déployer des interventions similaires.

"How to start that conversation?": Experiences of developing a virtual simulation about sexual health care for breast cancer survivors

Virtual simulation (VS) is an innovative and engaging knowledge translation strategy that can improve healthcare providers' knowledge and skills. However, there is no known literature published related to the use of simulation to improve cancer survivorship care. In this paper, we describe our experience of developing a VS to educate primary healthcare professionals about sexual health disturbances among breast cancer survivors. Based on literature in other contexts, this VS may help increase health professionals' knowledge and skills needed to assist breast cancer survivors with sexual health concerns. Our VS development experience can be used to encourage and guide other researchers planning to develop similar interventions in the future.

Palliative Radiation Therapy: The Role of Radiation Therapy in Palliative and End-of-Life Care

BACKGROUND

 Radiation therapy (RT) remains one of the main pillars of cancer treatment, alongside systemic therapy and surgery. More than half of people with cancer will receive RT at some point during their treatment trajectory. Although RT contributes to cure in a substantial number of patients, more than half of patients treated with RT are treated with palliative intent. RT plays an integral role in alleviating symptoms, preserving function, and improving quality of life for patients with cancer.

OBJECTIVES

 The aim of this article is to provide information on the role of RT in palliative and end-of-life care.

METHODS

 A review of the literature and professional guidelines on palliative RT was performed.

FINDINGS

 This article provides foundational information for nurses on indications for palliative RT, possible side effects and toxicities associated with palliative RT, and challenges and barriers that may be encountered when considering palliative RT. Nursing implications, including the importance of a palliative approach to care, are discussed.

Pharmacists' practices and views regarding management of sexual health in patients with cancer

INTRODUCTION

Sexual health issues associated with cancer can significantly impact patients' psychosocial well-being and overall quality of life. These issues are frequently medication-related, placing pharmacists in an opportune position to manage sexual health concerns in patients with cancer. Currently, no literature exists exploring pharmacists' practices related to the management of sexual health in oncology patients.

METHODS

An anonymous, descriptive, cross-sectional, web-based survey was conducted to elicit pharmacists' views and practices regarding managing sexual health in oncology patients. Pharmacists practicing in Canada who provide care to adult malignant hematology or oncology patients were eligible to participate. The survey was disseminated through the Canadian Association of Pharmacy in Oncology and through informal oncology pharmacy practitioner networks.

RESULTS

Of the 102 pharmacists who participated, 96 completed the survey in its entirety. Most respondents were female, practiced in Alberta, and primarily saw oncology patients in outpatient cancer facilities. Although 85% of participants felt pharmacists should be involved in giving patients an opportunity to discuss sexual health, only 8% reported managing sexual health in at least 50% of their oncology patients. The most commonly agreed upon barriers to this were presence of family members and friends at appointments, lack of knowledge or training, limited time, and the belief that sexual health is not applicable to all oncology patients.

CONCLUSIONS

This study explored pharmacists' views and practices regarding managing sexual health in patients with cancer. Several barriers were identified, which may aid in future development of resources to assist pharmacists in routinely addressing sexual health in oncology patients.

Virtual Cancer Care Equity in Canada: Lessons From COVID-19

The COVID-19 pandemic radically shifted healthcare delivery to patients with cancer. Virtual cancer care, or the remote delivery of health care, has become an important resource for patients in Canada to maintain access to cancer care during the pandemic. With an increased number of people regularly accessing the internet and smartphones being ubiquitous for nearly all ages, technology in health care has grown. Virtual cancer care has been referenced as the fourth pillar of cancer care and it appears it may be here to stay. This article explores the benefits and challenges associated with virtual cancer care and outlines the importance of ensuring it is safe and equitable. Oncology nurses can identify where virtual care can be used to mitigate inequities and call attention when these tools exacerbate inequities.

Physiological and perceptual responses during walking at set and preferred pace in normal and overweight adults

BACKGROUND

This study aimed to investigate the influence of body weight, exercise modality, and pace on physiological and perceptual responses to determine the relation between perceptual and physiological responses.

METHODS

Aerobically untrained, normal weight, and overweight males and females participated. Participants were randomly assigned to one exercise condition for a 1-mile walk.

RESULTS

Prescribed pace resulted in a greater physiological stress than self-selected pace (all p < 0.001) through blood lactate (1.3 ± 0.4 vs 1.7 ± 0.5 mmol), systolic blood pressure (128.9 ± 10.3 vs 139.2 ± 13.2 mmHg), heart rate recovery (2.1 ± 1.7 vs 4.5 ± 2.6 min), oxygen consumption (15.1 ± 2.6 vs 18.1 ± 3.6 ml/kg/min), heart rate (111.7 ± 16.6 vs 134.4 ± 8.3 bpm), and energy expenditure (5.5 ± 1.4 vs 6.8 ± 1.7 kcal/min). Overweight individuals exhibited higher values than normal weight for heart rate (113 ± 8.8 vs 125.5 ± 13.2 bpm, p < 0.001), percentage of max heart rate (60.7 vs 69.0%, p < 0.001), percent of VO2peak (42.2 vs 55.6%, p < 0.001), and total energy expenditure (100.9 ± 27.4 vs 114.1 ± 33.5 kcal, p = 0.022). Greater perceived effort was seen on a treadmill (6.3 ± 0.5 vs 12.5 ± 2.0 RPE, p < 0.001) and at prescribed pace (6.5 ± 1.1 vs 8.9 ± 1.9 RPE, p < 0.001).

CONCLUSION

A novel finding of this study was the increased physiological stress and perception of effort on a treadmill and at a prescribed pace, while total energy expenditure showed no significant differences. This could indicate an unfavorable perception and less affective response to the treadmill modality. These results indicate exercise at self-selected pace in preferred environments promotes enjoyable experiences with similar health benefits as those during prescribed higher intensity exercise.

Transforming Canada's role in global cancer control

Cancer has not been an explicit priority of Canada's international health and development agenda, but it is key to realising the country's Sustainable Development Goal commitments. Multiple converging political, health, and social forces could now drive support for a more integrated Canadian approach to global cancer control. Success will depend on the extent to which Canadian leaders and institutions can build consensus as a community and agree to work together. Collaboration should include agreement on the framing and prioritisation of the core issues, building a broad coalition base, aligning with priorities of international partners, and on a governance structure that reflects the principles of equity, diversity, and inclusion. This Series paper will discuss global cancer control within Canada's global health agenda, how Canada can address its history of colonisation and present-day disparities in its global work, and the challenges and opportunities of creating a Canadian global cancer control network.

Supporting People and Their Caregivers Living with Advanced Cancer: From Individual Experience to a National Interdisciplinary Program

OBJECTIVES

To discuss the unmet needs of patients living with advanced cancer and their caregivers and to review strategies, including collaborating with community and non-profit organizations, to help improve the experience of living with, and beyond, advanced cancer.

DATA SOURCES

Published articles, first person experience (SB), community organization input, and survey data (Canadian Cancer Society).

CONCLUSION

People living with advanced cancer face significant challenges, including persistent physical symptoms and psychosocial concerns, difficulties with coordination of care, and possible lack of available resources and supports if the person is no longer being followed by cancer health care professionals. More research is required to better understand the needs of patients and their caregivers living with advanced cancer. Existing resources and supports may be inadequate for this population, and delineation of the unique needs of this population may lead to tailored care plans and, ultimately, an improved experience for patients and caregivers alike.

IMPLICATIONS FOR NURSING PRACTICE

Oncology nurses are ideally suited to care for this population to help elucidate their unique unmet needs and collaborate with patients and other clinicians to develop interventions to address such unmet needs. Oncology nurses can liaise with community organizations to identify sources of support and resources for patients and their loved ones and advocate for improved care for patients affected by advanced cancer.

Looking within and beyond our borders: Exemplars of international initiatives involving CANO/ACIO members

The Canadian Association of Nurses in Oncology/Association Canadienne des Infirmières en Oncologie (CANO/ACIO) is committed to being an influencing force globally. Its role in international work has been an important aspect of the Strategic Plan over the past five years. Beginning in 2015, following an environmental scan, literature review, and member input, the "Framework for International Engagement, Exchange, Influence and Partnerships" was articulated. This article focuses on experiences and exemplars of work in international settings that focus on symptom management, supportive care, education, and the integration of the CANO standards and competencies into other settings. Exemplars from East Africa (Rwanda and Kenya) and Central America (Costa Rica) in which CANO/ACIO members were involved will be highlighted.

The Oncology and Sexuality, Intimacy, and Survivorship Program Model: An Integrated, Multi-disciplinary Model of Sexual Health Care within Oncology

Cancer-related sexual dysfunction is documented as one of the most distressing and long-lasting survivorship concerns of cancer patients. Canadian cancer patients routinely report sexuality concerns and difficulty getting help. In response to this gap in care, clinical practice guidelines were recently published in the Journal of Clinical Oncology. A sweeping trend is the creation of specialized clinics for patients' sexual health concerns. However, this much-needed attempt to address this service gap can be difficult to sustain without addressing the cancer care system from a broader perspective. Herein, we describe the implementation of a tiered systemic model of cancer-related sexual health programming in a tertiary cancer center. This program follows the Permission, Limited Information, Specific Suggestions, Intensive Therapy (PLISSIT) model, used previously for guiding individual practitioners. Visually, the model resembles a pyramid. The top 2 levels, corresponding to Intensive Therapy and Specific Suggestions, are comprised of group-based interventions for common cancer-related sexual concerns and a multi-disciplinary clinic for patients with complex concerns. The bottom 2 levels, corresponding to Permission and Limited Information, consist of patient education and provider education and consultation services. We describe lessons learned during the development and implementation of this program, including the necessity for group-based services to prevent inundation of referrals to the specialized clinic, and the observation that creating specialized resources also increased the likelihood that providers would inquire about patients' sexual concerns. Such lessons suggest that successful sexual health programming requires services from a systemic approach to increase sustainability.

Development, implementation, and evaluation of a multidisciplinary oncology sexual health clinic in a Canadian cancer care setting

PURPOSE

Untreated cancer-related sexual health concerns cause significant distress for cancer survivors. To appropriately address the complex sexual health needs of cancer patients, we piloted a specialized, multidisciplinary oncology sexual health clinic within a tertiary cancer center. A quality assurance evaluation was conducted.

METHODS

During once monthly half-day clinics, a multidisciplinary team of psychologists, advanced practice nurses, and radiation and gynecological oncologists offered specialist integrated care to oncology patients. Patients completed assessment questionnaires prior to each clinic appointment and a follow-up telephone interview approximately 4 months after their initial appointment.

RESULTS

Over the 2-year pilot, 224 patients were referred to the cancer center's broader sexual health program; 100 patients were triaged to the clinic. A total of 79 new and 58 follow-up appointments were offered. Average wait time for an initial visit was 97 days. Patients' most frequent concerns included vulvovaginal atrophy, dyspareunia, reduced sexual desire, and erectile dysfunction. Self-reported sexual distress was well above the clinical cutoff at baseline (N = 77, M = 29.78, SD = 12.74). A significant reduction in sexual distress was observed at follow-up (N = 67, M = 21.90, SD = 11.34, t(66) = 7.41, p < 0.001).

CONCLUSIONS

Referral rates indicate a high demand for specialized sexual health services within cancer care. Ongoing specialist care is needed to appropriately address the multifaceted sexual concerns of cancer survivors and to adequately manage high distress and symptom comorbidity.

IMPLICATIONS FOR CANCER SURVIVORS

Results inform a more comprehensive characterization of the presenting concerns of cancer survivors seeking multidisciplinary sexual health care.

Perspectives of hematology oncology clinicians about integrating palliative care in oncology

Patients with hematologic malignancies receive palliative care (pc) less frequently and later than patients with solid tumours. We compared survey responses of hematology oncology clinicians with other oncology clinicians to better understand their challenges with providing primary pc or using secondary pc. Patients' negative perceptions of pc and limited time or competing priorities were challenges for all clinicians. Compared with other oncology clinicians, more hematology oncology clinicians perceived pc referral criteria as too restrictive (40% vs. 22%, p = 0.021) and anticipated that integrating pc supports into their practice would require substantial change (53% vs. 28%, p = 0.014). This study highlights barriers that may need targeted interventions to better integrate pc into the care of patients with hematologic malignancies.

The experiences of individuals re-engaging in sexual relationships following a bone marrow transplant: A grounded theory study

PURPOSE

Sexual health is often neglected following a bone marrow transplant. The purpose of this study was to develop an in-depth explanation of the process that patients undergo when re-engaging in sexual relationships following a bone marrow transplant.

METHODS

A Straussian Grounded Theory methodology was employed. Ten bone marrow transplant patients (seven men, three women), participated in a semi-structured interview between October 2018 and April 2019.

RESULTS

A theoretical model of the process of re-engaging in a sexual relationship following a bone marrow transplant evolved over time. Four categories emerged from the data: identifying importance, taking responsibility, seeking resources, and navigating the partnered-relationship. Gender-specific details permeated all of these categories. These occurred in a non-linear process of 'seeking a new normal' and could apply at any time point during the treatment trajectory.

CONCLUSIONS

The model offers an explanation of the process participants went through during their illness and identifies ways that participants navigated change. Having intimate conversations often helped in targeting sexual recovery and affected the ease of transition in dealing with the transition to a 'new normal'.

Influence of clinical context on interpretation and use of an advance care planning policy: a qualitative study

BACKGROUND

Advance care planning is a process through which people share their values, goals and preferences regarding future medical treatments with the purpose of aligning care received with patient wishes. The objective of this study was to explore perspectives from patients and clinicians in 4 clinical settings to understand how context influences interpretation and application of advance care planning processes.

METHODS

This study used a qualitative interpretive descriptive design. Patient and clinician participants were recruited across 4 clinical outpatient settings (cancer, heart failure, renal failure and supportive living) in Calgary and Edmonton. Data were collected between 2014 and 2015 by means of recorded one-on-one semistructured interviews. We analyzed the data using thematic analysis in 2016-2017.

RESULTS

Thirty-four patients and 34 clinicians participated in interviews. Themes common to all 4 contexts were lack of shared understanding between patients and clinicians, and a lack of consistent clinical process related to advance care planning. Advance care planning understanding and process varied substantially between contexts. This variation seemed to be driven by differences in perceptions around disease burden and the nature of the physician-patient relationship.

INTERPRETATION

Provision of a system-wide policy and procedural framework alone was not found to be sufficient to form a standardized approach to advance care planning, as considerable variability existed in advance care planning process between and within clinical settings. Quality-improvement methods that consider local processes, gaps and barriers can help in developing a consistent, comprehensive process.

Palliative sedation and medical assistance in dying: Distinctly different or simply semantics?

Medical assistance in dying (MAiD) and palliative sedation (PS) are both legal options in Canada that may be considered by patients experiencing intolerable and unmanageable suffering. A contentious, lively debate has been ongoing in the literature regarding the similarities and differences between MAiD and PS. The aim of this paper is to explore the propositions that MAiD and PS are essentially similar and conversely that MAiD and PS are distinctly different. The relevance of such a debate is apparent for clinicians and patients alike. Understanding the complex and multi‐faceted nuances between PS and MAiD allows patients and caregivers to make more informed decisions pertaining to end‐of‐life care. It is hoped that this paper will also serve to foster further debate and consideration of the issues associated with PS and MAiD with a view to improve patient care and the quality of both living and dying in Canada.

Sexuality after hematopoietic stem cell transplantation: A mixed methods study

PURPOSE

This study examined patients' experiences of sexuality following hematopoietic stem cell transplantation. A secondary aim of the study was to explore healthcare provider-patient communication about sexuality.

METHODS

A mixed methods design was employed with an embedded qualitative-quantitative approach whereby the quantitative data were used to supplement the qualitative results. Participants (8 male and 3 female) participated in semi-structured interviews and also completed the FACT-BMT questionnaire.

RESULTS

Qualitative themes that emerged included: changes in sexual function (such as with desire and arousal), changes in relation to self (such as with body image, sexual identity), changes in relation to others (such as with current relationships, starting new relationships, fear of exposure to 'germs') and the experience of discussing sexual health concerns with healthcare providers. Quantitative data from the FACT-BMT revealed that participants reported low satisfaction with their sex life but remained interested in sex. The majority of participants reported dissatisfaction with the appearance of their body and most were not concerned about fertility.

CONCLUSION

This study documents the physical and psychosocial sexual health concerns reported in male and female recipients of HSCT. Concerns were present even for those many years post-HSCT. Implications include suggestions for healthcare providers regarding patient education and assessment of sexual health changes in patients throughout the HSCT trajectory and continuing well into survivorship.

Patient, family member, and clinician perspectives on advance care planning (ACP) in hematology and hematopoietic stem cell transplantation (HSCT)

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Background: Studies have found that ACP engagement remains low in patients undergoing HSCT in spite of the high risks of treatment-related morbidity and mortality. Methods: This qualitative study used Thorne’s Interpretive Description methodology. Participants were accrued from hematological malignancy outpatient clinics at a tertiary oncology center and underwent audio-recorded semi-structured interviews. Analysis involved meticulous review of interview transcripts. The constant comparative method was utilized; data collection occurred concurrently with analysis until saturation of themes was achieved. Results: The study involved 6 patients, 5 family members and 8 clinicians (physicians, nurses, social worker). Participants thought that ACP was both acceptable and important yet many had not engaged in ACP. Perceived barriers to ACP included: system-related barriers such as lack of process for ACP, lack of time and/or resources; patient-related factors such as lack of understanding of disease, prognosis and/or expectations of HSCT, lack of patient/family understanding of ACP, a desire to ‘focus on positives’; and disease/treatment-related factors such as unpredictability of the disease and treatment trajectories in hematology and HSCT. Potential facilitators identified by participants included: integrating ACP as part of routine HSCT care, involving the multidisciplinary team in ACP, and introducing ACP early and revisiting frequently. Conclusions: This study revealed various barriers and facilitators related to participation in ACP. We are using the results of this study to inform and tailor interventions on ACP at our center. Introducing ACP as part of standard care in HSCT and providing ongoing facilitation of ACP, including discussion of disease and treatment expectations at the outset, and when complications arise, may assist patients and families in recognizing how ACP fits into their care. Given the inherent unpredictability in this population, we suggest revisiting ACP frequently to optimize patient experience and ensure patients and family members are aware of other treatment options including supportive and palliative care.

Patient and healthcare perspectives on the importance and efficacy of addressing spiritual issues within an interdisciplinary bone marrow transplant clinic: a qualitative study

OBJECTIVES

The purpose of this study was to use a qualitative approach to better understand the importance and efficacy of addressing spiritual issues within an interdisciplinary bone marrow transplant clinic from the perspectives of patients and healthcare providers.

SETTING

Participants were recruited from the bone marrow transplant clinic of a large urban outpatient cancer care centre in western Canada.

PARTICIPANTS

Focus groups were conducted with patients (n=7) and healthcare providers (n=9) to explore the importance of addressing spiritual issues across the treatment trajectory and to identify factors associated with effectively addressing these needs.

RESULTS

Data were analysed using the qualitative approach of latent content analysis. Addressing spiritual issues was understood by patients and healthcare providers, as a core, yet under addressed, component of comprehensive care. Both sets of participants felt that addressing basic spiritual issues was the responsibility of all members of the interdisciplinary team, while recognising the need for specialised and embedded support from a spiritual care professional. While healthcare providers felt that the impact of the illness and treatment had a negative effect on patients' spiritual well-being, patients felt the opposite. Skills, challenges, key time points and clinical indicators associated with addressing spiritual issues were identified.

CONCLUSIONS

Despite a number of conceptual and clinical challenges associated with addressing spiritual issues patients and their healthcare providers emphasised the importance of an integrated approach whereby basic spiritual issues are addressed by members of the interdisciplinary team and by an embedded spiritual care professional, who in addition also provides specialised support. The identification of clinical issues associated with addressing spiritual needs provides healthcare providers with clinical guidance on how to better integrate this aspect of care into their clinical practice, while also identifying acute incidences when a more targeted and specialised approach may be of benefit.

Do patients think that dry powder inhalers can be used interchangeably?

As recognised in management guidelines, patients are the most important group of people in any prescribing decision. Despite their importance, few studies have asked what patients think about being switched between different inhalers. This paper reports two such studies, one involving interviews of a sample of patients and the other consisting of a quantitative survey of patients across five countries. In the qualitative study, four of the five patients interviewed reported that they would be confused, worried and unhappy about a switch in their dry powder inhaler and would revisit their physician to be shown how to use the inhaler or to ask for a new prescription for their old inhaler. In the quantitative survey of 499 patients with asthma, more than half (51%) were opposed to their current dry powder inhaler being replaced by a substitute device, with 83% reporting concerns. There was considerable concern about training in use of the new device and confusion about the need for change. Almost a quarter of patients (23%) would want training, and 23% of patients thought they would need information about the new inhaler. From limited information, it appears that patients would be concerned about switching of their existing dry powder inhaler for another, with the potential for confusion, need for additional consultations and need for training in the new device.

Best practice in the use of spirometry

This article examines spirometry as a method of detecting lung disease, particularly chronic obstructive pulmonary disease (COPD). Methods of producing an accurate assessment and identifying acceptable traces are outlined, and contraindications are discussed.

Implementing a discharge assessment tool in palliative home care

With an aging population and limited health care resources, reflection on end-of-life care is essential. While terminally ill cancer patients spend much of their last year in the home, the literature reveals that the majority of these patients would also prefer to die at home. Despite patients' and families' cited preference for home deaths, dying at home continues to be infrequent. In Edmonton's Capital Health Region (CHR) only 16% of cancer patients died at home in 1999. While many reasons for the low incidence of home death are cited, little data exists regarding discharges from the palliative home care program in the CHR. As such, it is difficult to assess where resources are needed in the community. The implementation of a discharge assessment tool for use in the Capital Health Palliative Home Care program may provide insight into potential correlates of home death. Not only providing information on individual patients, the inclusion of such data in the palliative home care database would allow for trends to be monitored over time.

Host recognition by the tobacco hornworm is mediated by a host plant compound

It is generally believed that animals make decisions about the selection of mates, kin or food on the basis of pre-constructed recognition templates. These templates can be innate or acquired through experience. An example of an acquired template is the feeding preference exhibited by larvae of the moth, Manduca sexta. Naive hatchlings will feed and grow successfully on many different plants or artificial diets, but once they have fed on a natural host they become specialist feeders. Here we show that the induced feeding preference of M. sexta involves the formation of a template to a steroidal glycoside, indioside D, that is present in solanaceous foliage. This compound is both necessary and sufficient to maintain the induced feeding preference. The induction of host plant specificity is at least partly due to a tuning of taste receptors to indioside D. The taste receptors of larvae fed on host plants show an enhanced response to indioside D as compared with other plant compounds tested.

The role of Ultrabithorax in the patterning of adult thoracic muscles in Drosophila melanogaster

Mutations in the homeotic gene, Ultrabithorax (Ubx), result in the transformation of the third thoracic (T3) segment into the second thoracic (T2) segment. Although it has been well established that these mutations have striking effects on adult epidermal structures in T3, the effect of these mutations on the adult musculature has been controversial. In this study, a series of Ubx regulatory mutations, anterobithorax, bithorax, postbithorax, and bithoraxoid, as well as combinations of these alleles were used to reevaluate the role of Ubx in the patterning of the T3 musculature. Homeotic indirect and direct flight muscles (IFMs and DFMs) were identified in the transformed T3 segment of all alleles and allelic combinations with the exception of postbithorax. We critically evaluated the pattern and amount of these muscles and found that while the amount and/or quality of homeotic IFMs increased, the amount of homeotic DFMs did not vary significantly as the severity of the ectodermal transformation increased. Because Ubx is not expressed in the adult mesoderm of T3, these results suggest that inductive cues play a major role in the patterning of adult thoracic muscles. We provide a model that illustrates the central role of inductive cues in generating the final adult muscle pattern in the thorax.

Imaginal pioneers prefigure the formation of adult thoracic muscles in Drosophila melanogaster

In insects, specialized mesodermal cells serve as templates to organize myoblasts into distinct muscle fibers during embryogenesis. In the grasshopper embryo, large mesodermal cells called muscle pioneers extend between the epidermal attachment points of future muscle fibers and serve as foci for myoblast fusion. In the Drosophila embryo, muscle founder cells serve a similar function, organizing large numbers of myoblasts into larval muscles. During the metamorphosis of Drosophila, nearly all larval muscles degenerate and are replaced by a set of de novo adult muscles. The extent to which specialized mesodermal cells homologous to the founders and pioneers of the insect embryo are involved in the development of adult-specific muscles has yet to be established. In the larval thorax, the majority of imaginal myoblasts are associated with the imaginal discs. We report here the identification of a morphologically distinct class of disc-associated myoblasts, which we call imaginal pioneers, that prefigures the formation of at least three adult-specific muscles, the tergal depressor of the trochanter and dorsoventral muscles I and II. Like the muscle pioneers of the grasshopper, the imaginal pioneers attach to the epidermis at sites where the future muscle insertions will arise and erect a scaffold for developing adult muscles. These findings suggest that a prior segregation of imaginal myoblasts into at least two populations, one of which may act as pioneers or founders, must occur during development.

Octopamine mimics the effects of parasitism on the foregut of the tobacco hornworm Manduca sexta

The parasitic braconid wasp Cotesia congregata lays its eggs inside the body of the larval stage of its host, the moth Manduca sexta. The Cotesia congregata larvae develop within the hemocoel of their host until their third instar, when they emerge and spin cocoons and pupate on the outer surface of the caterpillar. From this time until their death approximately 2 weeks later, the Manduca sexta larvae show striking behavioral changes that include dramatic declines in spontaneous activity and in the time spent feeding. Coincident with these behavioral changes, it is known that octopamine titers in the hemolymph of the host become elevated by approximately 6.5-fold. Octopamine is an important modulator of neural function and behavior in insects, so we examined hosts for neural correlates to the behavioral changes that occur at parasite emergence. We found that, in addition to the changes reported earlier, after parasite emergence (post-emergence), Manduca sexta larvae also showed marked deficits in their ability to ingest food because of a disruption in the function of the frontal ganglion that results in a significant slowing or the absence of peristaltic activity in the foregut. This effect could be produced in unparasitized fifth-instar larvae by application of blood from post-emergence parasitized larvae or of 10(−6)mol l(−1)d,l-octopamine (approximately the level in the hemolymph of post-emergence larvae). In contrast, blood from parasitized larvae before their parasites emerge or from unparasitized fifth-instar larvae typically had no effect on foregut activity. The effects of either post-emergence parasitized blood or 10(−6)mol l(−1) octopamine could be blocked by the octopamine antagonists phentolamine (at 10(−5)mol l(−1)) or mianserin (at 10(−7)mol l(−1)).

Homeotic gene expression in the wild-type and a homeotic mutant of the moth Manduca sexta

Antibodies were used to examine the expression patterns of Antennapedia (Antp), Ultrabithorax (Ubx), Ubx and abdominal-A combined (Ubx/abd-A), and Distalless (Dll) in the embryos of the moth Manduca sexta. We found that the spatial and temporal pattern of Antp expression in Manduca was correlated with the anterior migration of two patches of epithelium that include the anterior-most tracheal pits, and with the development of functional spiracles. Ubx expression showed an intricate pattern which suggests complex regulation during development. Throughout Manduca embryogenesis the expression of Ubx/Abd-A and Dll was similar to that reported for other insects. However, there was no apparent reduction in Ubx/Abd-A expression in the Manduca abdominal proleg primordia that expressed Dll. The expression of these four proteins was also examined in embryos of the Manduca homozygous homeotic mutant Octopod (Octo). The Octo mutation results in the transformation of A1 and A2 in the anterior direction, with homeotic legs appearing on A1 and occasionally A2. Our results suggest that in Octo animals there is a reduction in the level of Ubx protein expression throughout its domain. Based on homeotic gene expression in wild-type and mutant Manduca and in other insects, we discuss potential roles of homeotic genes in insect morphological evolution.