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Biomedical subjects

J C Weeks

Publications and source records attributed to J C Weeks.

At least 55 records · Page 3Linked to original sources
PubMed1999

Respecified larval proleg and body wall muscles circulate hemolymph in developing wings of Manduca sexta pupae.

Most larval external muscles in Manduca sexta degenerate at pupation, with the exception of the accessory planta retractor muscles (APRMs) in proleg-bearing abdominal segment 3 and their homologs in non-proleg-bearing abdominal segment 2. In pupae, these APRMs exhibit a rhythmic 'pupal motor pattern' in which all four muscles contract synchronously at approximately 4 s intervals for long bouts, without externally visible movements. On the basis of indirect evidence, it was proposed previously that APRM contractions during the pupal motor pattern circulate hemolymph in the developing wings and legs. This hypothesis was tested in the present study by making simultaneous electromyographic recordings of APRM activity and contact thermographic recordings of hemolymph flow in pupal wings. APRM contractions and hemolymph flow were strictly correlated during the pupal motor pattern. The proposed circulatory mechanism was further supported by the findings that unilateral ablation of APRMs or mechanical uncoupling of the wings from the abdomen essentially abolished wing hemolymph flow on the manipulated side of the body. Rhythmic contractions of intersegmental muscles, which sometimes accompany the pupal motor pattern, had a negligible effect on hemolymph flow. The conversion of larval proleg and body wall muscles to a circulatory function in pupae represents a particularly dramatic example of functional respecification during metamorphosis.

Animals↗
PubMed1998

The costs and cost-effectiveness of unrelated donor bone marrow transplantation for chronic phase chronic myelogenous leukemia.

Unrelated donor transplantation prolongs survival in some patients with chronic myelogenous leukemia (CML) in chronic phase. However, there are growing concerns about the intensive resources required for this procedure given health care budget constraints. To address this issue, we conducted a study of the costs and cost-effectiveness of unrelated donor transplantation for chronic phase CML. The costs of transplantation were derived from 157 patients from the Brigham and Women's Hospital (BWH) and the Fred Hutchinson Cancer Research Center (FHCRC). Estimates of the effectiveness of transplantation were taken from our previous work using data from the International Bone Marrow Transplant Registry and the National Marrow Donor Program. The median cost of the first 6 months of care including donor identification, marrow collection, patient hospitalization for transplantation and all outpatient medications and readmissions through 6 months postmarrow infusion was $178,500 (range, $85,000 to $462,400) and the mean was $196,200. Mean costs for patients surviving beyond 6 months posttransplant were significantly lower than for patients dying within that period ($189,700 v $211,000, respectively, P =.03). Posttransplant follow-up costs were high for months 6 to 18, then decreased. The incremental cost-effectiveness of transplantation within 1 year of diagnosis versus -interferon therapy without transplant in the base case of a 35-year-old patient was $51,800/quality-adjusted life year (QALY) gained. Sensitivity analysis showed that most ratios were between $50,000 to $100, 000/QALY or within the intermediate zone of acceptable cost-effectiveness ratios.

Adolescent↗
PubMed1998

Benefits of colonoscopic surveillance and prophylactic colectomy in patients with hereditary nonpolyposis colorectal cancer mutations.

BACKGROUND: Predisposition genetic testing is now possible for many hereditary cancer syndromes, including hereditary nonpolyposis colorectal cancer. The optimal management of the elevated risk for cancer in carriers of mutations for hereditary nonpolyposis colorectal cancer is unclear. OBJECTIVE: To assess the life expectancy and quality-adjusted life expectancy benefits derived from endoscopic surveillance and prophylactic colectomy for persons who carry a mutation associated with hereditary nonpolyposis colorectal cancer. DESIGN: Decision analysis model. Lifetime risk for colorectal cancer, efficacy of surveillance and colectomy, stage-specific colorectal cancer mortality, and quality of life were included in the model. SETTING: Decision about a cancer prevention strategy at the time of a positive result on genetic testing. PATIENTS: Carriers of a mutation for hereditary nonpolyposis colorectal cancer who were 25 years of age. INTERVENTIONS: Immediate prophylactic colectomy; delayed colectomy on the basis of age, adenoma, or diagnosis of colorectal cancer; and endoscopic surveillance. Prophylactic surgical options were proctocolectomy with ileoanal anastomosis and subtotal colectomy with ileorectal anastomosis. MEASUREMENTS: Life expectancy and quality-adjusted life expectancy. RESULTS: All risk-reduction strategies led to large gains in life expectancy for carriers of a mutation for hereditary nonpolyposis colorectal cancer, with benefits ranging from 13.5 years for surveillance to 15.6 years for prophylactic proctocolectomy at 25 years of age compared with no intervention. The benefits of colectomy compared with surveillance decreased with increasing age and were minimal if colectomy was performed at the time of colorectal cancer diagnosis. When health-related quality of life was considered, surveillance led to the greatest quality-adjusted life expectancy benefit (3.1 years compared with proctocolectomy and 0.3 years compared with subtotal colectomy). CONCLUSIONS: Colonoscopic surveillance is an effective method of reducing risk for cancer in carriers of a mutation for hereditary nonpolyposis colorectal cancer. The individual patient's choice between prophylactic surgery and surveillance is a complex decision in which personal preferences weigh heavily.

Adult↗
PubMed1998

The quality of care for treatment of early stage breast carcinoma: is it consistent with national guidelines?

BACKGROUND: In response to the importance of early stage breast carcinoma as a public health concern and to the complexity of the clinical literature devoted to treatment of the disease, the National Institutes of Health has held a series of Consensus Development Conferences on the treatment of early stage breast carcinoma. The authors assessed compliance with standards of care for women treated in two states. METHODS: The authors identified patients diagnosed at 18 randomly selected hospitals (N = 1514) in Massachusetts and at 30 hospitals (N = 1061) in Minnesota. They collected data from medical records, patients, and their surgeons to assess compliance with four indicators of quality of care: radiation therapy after breast-conserving surgery, axillary lymph node dissection, chemotherapy for premenopausal women with positive lymph nodes, and hormonal therapy for postmenopausal women with positive lymph nodes and positive estrogen receptor status. RESULTS: Rates of compliance for 3 of the 4 standards of care were > 80% in both states. Only the rate for hormonal therapy for postmenopausal women was low (< 64%). However, the proportion of these women who received either chemotherapy or hormonal therapy was > 90% in both states. CONCLUSIONS: In the states studied, practice appears to be consistent with the results of national consensus conferences and clinical trials regarding the treatment of early stage breast carcinoma. For practices demonstrated to be associated definitively with better outcomes (for example, chemotherapy for premenopausal women with positive lymph nodes) or to be important with respect to prognosis (axillary lymph node dissection) high rates of compliance were observed.

Adult↗
PubMed1998

Relationship between cancer patients' predictions of prognosis and their treatment preferences.

CONTEXT: Previous studies have documented that cancer patients tend to overestimate the probability of long-term survival. If patient preferences about the trade-offs between the risks and benefits associated with alternative treatment strategies are based on inaccurate perceptions of prognosis, then treatment choices may not reflect each patient's true values. OBJECTIVE: To test the hypothesis that among terminally ill cancer patients an accurate understanding of prognosis is associated with a preference for therapy that focuses on comfort over attempts at life extension. DESIGN: Prospective cohort study. SETTING: Five teaching hospitals in the United States. PATIENTS: A total of 917 adults hospitalized with stage III or IV non-small cell lung cancer or colon cancer metastatic to liver in phases 1 and 2 of the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT). MAIN OUTCOME MEASURES: Proportion of patients favoring life-extending therapy over therapy focusing on relief of pain and discomfort, patient and physician estimates of the probability of 6-month survival, and actual 6-month survival. RESULTS: Patients who thought they were going to live for at least 6 months were more likely (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.8-3.7) to favor life-extending therapy over comfort care compared with patients who thought there was at least a 10% chance that they would not live 6 months. This OR was highest (8.5; 95% CI, 3.0-24.0) among patients who estimated their 6-month survival probability at greater than 90% but whose physicians estimated it at 10% or less. Patients overestimated their chances of surviving 6 months, while physicians estimated prognosis quite accurately. Patients who preferred life-extending therapy were more likely to undergo aggressive treatment, but controlling for known prognostic factors, their 6-month survival was no better. CONCLUSIONS: Patients with metastatic colon and lung cancer overestimate their survival probabilities and these estimates may influence their preferences about medical therapies.

Adult↗
PubMed1998

Segment-specific retention of a larval neuromuscular system and its role in a new, rhythmic, pupal motor pattern in Manduca sexta.

At pupation in Manduca sexta, accessory planta retractor muscles and their motoneurons degenerate in segment-specific patterns. Accessory planta retractor muscles in abdominal segments 2 and 3 survive in reduced form through the pupal stage and degenerate after adult emergence. Electromyographic and electrophysiological recordings show that these accessory planta retractor muscles participate in a new, rhythmic 'pupal motor pattern' in which all four muscles contract synchronously at approximately 4 s intervals for extended bouts. Accessory planta retractor muscle contractions are driven by synaptic activation of accessory planta retractor motoneurons and are often accompanied by rhythmic activity in intersegmental muscles and spiracular closer muscles. The pupal motor pattern is influenced by descending neural input although isolated abdominal ganglia can produce a pupal motor pattern-like rhythm. The robust pupal motor pattern first seen after pupal ecdysis weakens during the second half of pupal life. Anemometric recordings indicate that the intersegmental muscle and spiracular closer muscle component of the pupal motor pattern produces ventilation. Accessory planta retractor muscle contractions lift the flexible abdominal floor, to which the developing wings and legs adhere tightly. We hypothesize that, by a bellows-like action, the accessory planta retractor muscle contractions circulate hemolymph in the appendages. Morphometric analysis shows that dendritic regression is similar in accessory planta retractor motoneurons with different pupal fates, and that accessory planta retractor motoneurons begin to participate in the pupal motor pattern while their dendrites are regressed.

Animals↗
PubMed1998

Outcomes, preferences for resuscitation, and physician-patient communication among patients with metastatic colorectal cancer. SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments.

PURPOSE: To describe characteristics, outcomes, and decision making in patients with colorectal cancer metastatic to the liver, and to examine the relationship of doctor-patient communication with patient understanding of prognosis and physician understanding of patients' treatment preferences. PATIENTS AND METHODS: The Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT) was a prospective cohort study conducted at five teaching hospitals in the United States between 1989 and 1994. Participants in this study were hospitalized patients 18 years of age or older with known liver metastases who had been diagnosed with colorectal cancer at least 1 month earlier. Data were collected by patient interview and chart review at study entry; patients were interviewed again at 2 and 6 months. Data collected by physician interview included estimates of survival and impressions of patients' preferences for cardiopulmonary resuscitation (CPR). Patients and physicians were also asked about discussions about prognosis and resuscitation preferences. RESULTS: We studied 520 patients with metastatic colorectal cancer (median age 64, 56% male, 80% white, 2-month survival 78%, 6-month survival 56%). Quality of life (62% "good" to "excellent") and functional status (median number of disabilities = 0) were high at study entry and remained so among interviewed survivors at 2 and 6 months. Of 339 patients with available information, 212 (63%) of 339 wanted CPR in the event of a cardiopulmonary arrest. Factors independently associated with preference for resuscitation included younger age, better quality of life, absence of lung metastases, and greater patient estimate of 2-month prognosis. Of the patients who preferred not to receive CPR, less than half had a do-not-resuscitate note or order written. Patients' self-assessed prognoses were less accurate than those of their physicians. Physicians incorrectly identified patient CPR preferences in 30% of cases. Neither patient prognostication nor physician understanding of preferences were significantly better when discussions were reported between doctors and patients. CONCLUSIONS: A majority of patients with colorectal cancer have preferences regarding end of life care. The substantial misunderstanding between patients and their physicians about prognosis and treatment preferences appears not to be improved by direct communication. Future research focused on enhancing the effectiveness of communication between patients and physicians about end of life issues is needed.

Cardiopulmonary Resuscitation↗
PubMed1998

Use of breast-conserving surgery for treatment of stage I and stage II breast cancer.

PURPOSE: To assess the use of breast-conserving surgery in two states reported to differ with respect to surgical treatment of breast cancer. METHODS: A retrospective cohort study based on data collected from medical records and patients was performed among 1,514 patients diagnosed with early-stage breast cancer in Massachusetts and 1,061 patients in Minnesota. Patients were identified at 18 randomly selected hospitals in Massachusetts and at 30 hospitals in Minnesota. The rate of breast-conserving surgery in both states and the correlates of breast-conserving surgery among women eligible for the procedure were determined. RESULTS: The rate of breast-conserving surgery in both states was much higher than previously reported. Among those eligible for the procedure, nearly 75% underwent breast-conserving surgery in Massachusetts and nearly half did so in Minnesota. Significantly (P < .003) more women who underwent mastectomy in Minnesota (27%) than in Massachusetts (15%) reported that their surgeon did not discuss breast-conserving surgery with them. Among women who underwent mastectomy and who reported being informed of both surgical alternatives, more women (P < .001) in Minnesota (74%) than in Massachusetts (62%) said they ultimately chose mastectomy because their surgeon recommended it. In Massachusetts, women treated at teaching hospitals were twice as likely as other women to undergo breast-conserving surgery. In Minnesota, women over age 70 and those who lived in rural areas were less likely than other women to undergo breast-conserving surgery. CONCLUSION: Although the rate of breast-conserving surgery in each state was higher than expected based on earlier reports, the rates differed considerably between states. Additional studies are needed to determine whether variation in practice between geographic areas is due to differences in patients' preferences and values or to surgeons' propensity for one type of surgery based on where they practice.

Aged↗
PubMed1998

Patient-reported symptoms after primary therapy for early prostate cancer: results of a prospective cohort study.

PURPOSE: To assess complications of therapy for early (nonmetastatic) prostate cancer. PATIENTS AND METHODS: A prospective study of a cohort of 279 men who sought treatment advice and completed required pretreatment forms. The measures were self-reported patient symptoms and other measures of quality of life before therapy and at 3 and 12 months afterward. RESULTS: Bowel and bladder symptoms were uncommon pretreatment. Patients frequently reported irritative bowel and bladder symptoms at 3 months after radiotherapy, although these subsided somewhat at 12 months. Substantial ("a lot") urinary incontinence and wearing of absorptive pads were reported by 11% and 35% at 12 months after surgery and varied little by age. Incontinence occurred after radiotherapy infrequently, and only in men more than 65 years old. Inadequate erections, present in one third of men pretreatment, were nearly universal at 3 months after surgery, although some improvement, primarily in men under 65 years of age, was evident at 12 months. Sexual dysfunction after radiotherapy increased less but continually through 12 months, suggesting that observed treatment-related differences would decline with further follow-up. CONCLUSION: External-beam radiotherapy of early prostate cancer is followed by bowel and bladder irritability, by increasingly severe sexual dysfunction and, in men aged more than 65 years, occasional urinary incontinence. Greater sexual dysfunction and urinary incontinence occur in the year following radical prostatectomy. These postsurgical complication rates from patient questionnaires are greater than have been reported in other treatment series and confirm the results of two retrospective studies of patient-reported complications.

Adult↗
PubMed1998

Cost-effectiveness of routine radiation therapy following conservative surgery for early-stage breast cancer.

PURPOSE: To examine the cost-effectiveness of radiation therapy following conservative surgery for early-stage breast cancer. METHODS: Using a Markov model, a cost-utility analysis was performed to compare a strategy of radiation therapy versus no radiation therapy in a hypothetical cohort of 60-year-old women following conservative surgery. Local recurrence, distant recurrence, and survival rates used in the model were derived from randomized trial data. Utilities for the nonmetastatic health states were collected from actual patients. Direct medical costs were estimated using data from a single institution. Transportation and time costs were also estimated. Years of life, quality-adjusted life-years (QALYs), costs, and incremental cost/QALY over a 10-year time horizon were calculated by the model for each strategy. RESULTS: The addition of radiation therapy results in a cost increase of $9,800 per patient, no change in life expectancy, and an increase of 0.35 QALYs per patient, which leads to an incremental cost-effectiveness ratio of $28,000/QALY, which is well below $50,000/QALY, a commonly cited threshold for cost-effective care. Sensitivity analysis shows the ratio to be heavily influenced by the cost of radiation therapy and the quality-of-life benefit that results from decreased risk of local recurrence. CONCLUSION: Radiation therapy following conservative surgery is cost-effective compared with other accepted medical interventions. This study illustrates the importance of considering an intervention's effect on quality of life, as well as survival in defining cost-effectiveness.

Breast Neoplasms↗
PubMed1998

Programmed cell death of an identified motoneuron in vitro: temporal requirements for steroid exposure and protein synthesis.

Ecdysteroid hormones trigger the programmed cell death (PCD) of a segmental subset of accessory planta retractor (APR) motoneurons at pupation in the moth, Manduca sexta. APRs from abdominal segment four [APR (4)s] survive through the pupal stage, whereas homologous APR(6)s die 24-48 h after pupal ecdysis (PE) (the shedding of the larval cuticle), in response to the prepupal peak of ecdysteroids. Following retrograde labeling with the vital fluorescent dye, DiI, the morphology of APR(4)s and APR(6)s in vivo was examined at PE and 24-48 h later. During this period, APR(4) somata remained large and ovoid while APR(6)s somata became shrunken and rounded. Similar phenotypes were observed when DiI-labeled APRs were cultured at PE and examined 24 h to 1 week later. During initial shrinkage and rounding of APR(6)s, the plasma membrane remained intact but DNA condensation occurred and mitochondrial activity was lost. The requirements for ecdysteroids and new protein synthesis for APR(6) death were tested by culturing cells with ecdysteroids and cycloheximide (CHX). When cultured at PE, the death of APR(6)s was independent of further exposure to ecdysteroids and could not be blocked by CHX. In contrast, APR(6)s cultured 24 h earlier required additional exposure to ecdysteroids to die and their death was inhibited by CHX. Thus, the final 24 h of larval life represents an important transition period in the commitment of APR(6)s to undergo PCD, and is of interest for pursuing underlying mechanisms of steroid-induced PCD.

Animals↗
PubMed1997

Unrelated donor bone marrow transplantation for chronic myelogenous leukemia: a decision analysis.

BACKGROUND: Chronic myelogenous leukemia (CML) is an indolent but ultimately fatal disease. Because the natural history of CML varies and quality of life with CML may be excellent until shortly before death, deciding whether and when to pursue unrelated donor bone marrow transplantation is often difficult. OBJECTIVE: To compare early transplantation, delayed transplantation, and no transplantation for patients with chronic-phase CML on the basis of discounted, quality-adjusted life expectancy. DESIGN: A markov model comparing different strategies was constructed. This model considers patient age, quality of life, risk aversion, and the competing risks for CML progression and transplant toxicity. SETTING: Therapeutic decision at the time of diagnosis of CML. PATIENTS: The base case is a 35-year-old patient with intermediate-prognosis CML. Younger and older patients with better and worse prognoses are also evaluated. INTERVENTION: Early transplantation, delayed transplantation, and no transplantation. MEASUREMENTS: Quality-adjusted, discounted life expectancy. RESULTS: For patients with newly diagnosed CML, transplantation within the first year provides the greatest quality-adjusted expected survival, although this benefit decreases with increasing patient age. For a 35-year-old patient with intermediate-prognosis CML, transplantation within the first year results in 53 more discounted, quality-adjusted years of life expectancy than does no transplantation. This finding is robust even with varying baseline assumptions. CONCLUSIONS: These results support the use of early unrelated donor bone marrow transplantation for most patients with CML.

Age Factors↗
PubMed1997

Decision analysis--effects of prophylactic mastectomy and oophorectomy on life expectancy among women with BRCA1 or BRCA2 mutations.

BACKGROUND: Women with BRCA1 or BRCA2 mutations have an increased risk of breast cancer and ovarian cancer. Prophylactic mastectomy and oophorectomy are often considered as ways of reducing these risks, but the effect of the procedures on life expectancy has not been established. METHODS: In a decision analysis, we compared prophylactic mastectomy and prophylactic oophorectomy with no prophylactic surgery among women who carry mutations in the BRCA1 or BRCA2 gene. We used available data about the incidence of cancer, the prognosis for women with cancer, and the efficacy of prophylactic mastectomy and oophorectomy in preventing breast and ovarian cancer to estimate the effects of these interventions on life expectancy among women with different levels of risk of cancer. RESULTS: We calculated that, on average, 30-year-old women who carry BRCA1 or BRCA2 mutations gain from 2.9 to 5.3 years of life expectancy from prophylactic mastectomy and from 0.3 to 1.7 years of life expectancy from prophylactic oophorectomy, depending on their cumulative risk of cancer. Gains in life expectancy decline with age at the time of prophylactic surgery and are minimal for 60-year-old women. Among 30-year-old women, oophorectomy may be delayed 10 years with little loss of life expectancy. CONCLUSIONS: On the basis of a range of estimates of the incidence of cancer, prognosis, and efficacy of prophylactic surgery, our model suggests that prophylactic mastectomy provides substantial gains in life expectancy and prophylactic oophorectomy more limited gains for young women with BRCA1 or BRCA2 mutations.

Adult↗
PubMed1997

Steroid hormones act directly to trigger segment-specific programmed cell death of identified motoneurons in vitro.

In larvae of the hawkmoth, Manduca sexta, accessory planta retractor (APR) motoneurons undergo a segment-specific pattern of programmed cell death at pupation. APR death is triggered hormonally by the prepupal peak of the ecdysteroid, 20-hydroxyecdysone (20-HE). Previous studies found no evidence that cellular interactions regulate the segmental pattern of APR death in vivo. To test the hypothesis that 20-HE acts directly on APRs to trigger a cell-autonomous, segment-specific pattern of death, APRs were labeled with the fluorescent dyes DiI or DiA, removed from the nervous system before the prepupal peak, and placed in low-density cell culture. Physiological levels of 20-HE triggered the same segment-specific pattern of APR death in vitro as seen in vivo, both in cultures containing a single APR and in cultures containing two APRs removed from the same donor animal. The presence or absence of contact with other cells did not influence the APRs' responses to 20-HE. The death of APRs in culture was characterized by fragmentation or rounding up of the cell body and fragmentation of the neurites. These findings suggest that intrinsic segmental identity regulates whether these motoneurons live or die when exposed to a steroid hormone during development.

Animals↗
PubMed1997

Neural correlates of habituation of the proleg withdrawal reflex in larvae of the hawk moth, Manduca sexta.

The larval proleg withdrawal reflex of the hawk moth, Manduca sexta, exhibits robust habituation. This reflex is evoked by deflecting one or more mechanosensory planta hairs on a proleg tip. We examined neural correlates of habituation in an isolated proleg preparation consisting of one proleg and its segmental ganglion. Repeated deflection of a single planta hair caused a significant decrease in the number of action potentials evoked in the proleg motor nerve (which carries the axons of proleg retractor motor neurons). Significant response decrement was seen for interstimulus intervals of 10 s, 60 s and 5 min. Response decrement failed to occur in the absence of repetitive stimulation, the decremented response recovered spontaneously following a rest, and electrical stimulation of a body wall nerve facilitated the decremented response (a neural correlate of dishabituation). Adaptation of sensory neuron responses occurred during repeated hair deflections. However, when adaptation was eliminated by direct electrical stimulation of sensory neurons, the response in the proleg motor nerve still decreased significantly. Muscle recordings indicated that the response of an identified proleg retractor motor neuron decreased significantly during habituation training. Thus, habituation of the proleg withdrawal reflex includes a central component that is apparent at the level of a single motor neuron.

Animals↗
PubMed1997

Neural mechanisms of behavioral plasticity: metamorphosis and learning in Manduca sexta.

This review summarizes our current understanding of the neural circuit underlying the larval proleg withdrawal reflex (PWR) of Manduca sexta and describes how PWR function changes in two contexts: metamorphosis and learning. The first form of PWR plasticity occurs during the larval-pupal transformation, when the reflex is lost. One mechanism that contributes to this loss is the weakening of monosynaptic excitatory connection from proleg sensory neurons to proleg retractor motor neurons. This change is associated with the hormonally-mediated regression of proleg motor neuron dendrites, which may break synaptic contacts between the sensory and motor neurons. After pupation, some of the proleg motor neurons die in a segment-specific pattern that persists even after individual motor neurons are isolated from the nervous system and exposed to hormones in vitro. The second form of PWR plasticity involves short-term, activity-dependent changes in neural function during the larval stage. The nicotinic cholinergic connections from proleg sensory neurons to motor neurons exhibit several forms of plasticity including facilitation, depression, post-tetanic potentiation and two types of muscarinic modulation. Larval PWR behavior exhibits two simple forms of learning-habituation and dishabituation-which involve alterations in the central PWR circuit. These studies of a simple circuit illustrate neural mechanisms by which behaviors undergo both short- and long-term modifications.

Animals↗
PubMed1997

Patient preferences concerning the trade-off between the risks and benefits of routine radiation therapy after conservative surgery for early-stage breast cancer.

PURPOSE: To assess patients' preferences regarding the trade-off between risks and benefits of radiation therapy after conservative surgery for early-stage breast cancer. PATIENTS AND METHODS: Utilities (measures of preference) of 97 early-stage breast cancer patients treated with conservative surgery and radiation therapy and 20 medical oncology nurses were assessed for five health states using standard gambles. RESULTS: Patients had the highest mean utility for treatment with conservative surgery and radiation therapy without a local recurrence (0.92), intermediate utilities for treatment with conservative surgery alone followed either by no local recurrence or by a local recurrence salvaged by conservative surgery and radiation therapy (0.88 and 0.87, respectively), and the lowest utilities for treatment with or without radiation therapy followed by a local recurrence salvaged by mastectomy and reconstructive surgery (0.82 and 0.81, respectively). All differences between health states' utilities were significant (P < .0001), except between the two intermediate and two lowest rated health states. None of the clinical or sociodemographic factors examined explained more than 5% of the variability in the patients' utilities or their differences. Nurses' utilities were similar to those of the patients. CONCLUSIONS: These results strongly suggest that fear of a local recurrence and an actual local recurrence leading to mastectomy have such a negative impact on quality of life that patients are willing to accept the risks and inconvenience of radiation therapy to avoid them. There is also considerable interpatient variability that was not explained by the clinical or sociodemographic factors examined.

Adult↗