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At least 523 records · Page 29Linked to original sources
PubMed2002

Current surgical management of breast cancer.

Breast cancer surgery continues to become more conservative. Supporting this conservatism are (1) earlier diagnosis through mammographic screening, (2) an increasing role for diagnostic ultrasound and magnetic resonance imaging, (3) the further development of image-guided core-needle biopsy, and (4) the advent of sentinel lymph node biopsy as an alternative to conventional axillary dissection. For patients with duct carcinoma in situ, the addition of radiotherapy and tamoxifen to surgical excision reduces local recurrence but has not yet improved survival over the rate observed with excision alone. There may be low-risk subgroups of duct carcinoma in situ patients for whom conservative surgery alone is adequate treatment. For patients with invasive cancer, breast conservation remains underutilized. A small survival benefit from post-mastectomy adjuvant radiotherapy is offset by an increased incidence of cardiovascular mortality, a phenomenon which has not yet been demonstrated for radiotherapy following breast conservation. Sentinel lymph node biopsy represents a new standard of care for axillary lymph node staging in the large majority of breast cancer patients with high-risk duct carcinoma in situ and stage I-II invasive cancers. The procedure is feasible, accurate, and works best with a combination of blue dye and radioisotope mapping. After proper validation studies, patients with negative sentinel lymph nodes do not require axillary dissection. The prognostic significance of sentinel lymph node micrometastases identified by enhanced pathologic techniques remains a matter of debate. Prophylactic mastectomy reduces breast cancer incidence and mortality among those with a high-risk family history, and mutations of BRCA1-2, but has significant adverse psychosocial sequelae for a small and unpredictable fraction of patients and should not be undertaken lightly. Prophylactic oophorectomy should be offered to all women with BRCA1-2 mutations, especially those beyond the years of childbearing.

Breast Neoplasms↗
PubMed1981

Values and attitudes of medical students at an Australian University.

This paper reports the results of an Australian study in which successive cohorts of medical students at Flinders University were tested and retested in 1975, 1977, and 1979 to trace changes in their attitudes and values since their freshman year. All respondents completed the Rokeach Value Survey and specific attitude items concerned with federal government intervention in health insurance. Those respondents tested in 1977 and 1979 also completed a measure of general conservatism and rated the importance of a set of reasons for studying medicine as a career. The results showed considerable stability in both attitudes and value priorities, irrespective of cohort and time of testing. The students tended of favor government intervention in health insurance and to rate as most important those reasons concerned with helping others, working with people, and meeting challenges. Male and female students differed in the degree of importance they attached to some of the reasons, and these differences reflected commonly noted sex role differences.

Attitude↗
PubMedDate not supplied

Management of subcutaneous emphysema, pneumomediastinum, and pneumothorax during respirator therapy.

Pulmonary barotrauma developed in 18/430 patients receiving respirator support for longer than 12 hours. Pneumothorax occurred in 15 of these patients and was treated with tube thoracostomy and 15-20 cm H2O pleural suction. Full reexpansion of the lungs were achieved in all but three patients, two of whom had bronchopleural fistulae. Major complications occurred in 8/15 patients developing pneumothorax. We recommend extreme conservatism in clamping or removing tube thoracostomy. There should be no air leak and full lung expansion for 48 hours, followed by a trial of underwater seal drainage without recurrence of pneumothorax. Removal should be preceded by an additional trial of tube clamping.

Aged↗
PubMed1990

The COMPLY computer program for demonstrating compliance with national radionuclide air emission standards.

The Environmental Protection Agency (EPA) has proposed national radionuclide air emission standards for a number of source categories. One of these standards applies to Nuclear Regulatory Commission Licensees and non-Department of Energy facilities having the potential to release radionuclides to the atmosphere. Approximately 6000 facilities are subject to the standard, which limits the effective whole-body dose commitment to the maximally exposed individual from radionuclide releases to the atmosphere. A computer program to assist the regulated community in determining compliance has been developed by the EPA's Office of Radiation Programs. The computer program COMPLY calculates the dose to an individual residing outside the facility. The program considers dose from inhalation, ingestion of contaminated food, air immersion, and ground deposition. It is based on models developed by the National Council on Radiation Protection and Measurements (NCRP). Compliance procedures provided in COMPLY are designed to reduce the burden on the regulated community. The approach begins with simple-to-use methods that are very conservative in determining compliance. The methods become progressively less conservative but more complicated at succeeding levels. Each higher level requires the input of site-specific information, but allows a more realistic estimate of dose. This paper describes the COMPLY program, and provides estimates of the work required and the degree of conservatism in the dose computed at each level.

Air Pollution, Radioactive↗
PubMed1993

Application of systematic error bounds to detection limits for practical counting.

Overly optimistic estimates of detection limits can result in the use of unrealistic conservatism for decisions about the presence of activity. In some practical counting situations, overly conservative detection limits can result in economically impractical actions. To help preclude such actions, systematic error bounds, uncertainties, and confidence levels can be used when determining critical levels (Lc), detection limits (Ld), and minimum detectable concentrations. This note discusses the selection of such error bounds and the development of detection limit parameters for practical applications. These parameters are shown to be successfully employed in sample activity and measurement process capability decisions for typical counting instruments.

Radiometry↗
PubMed1998

Primary shielding barriers for diagnostic x-ray facilities: a new model.

Traditional methods of diagnostic x-ray shielding design assume that the raw primary beam impinges directly on the structural barrier with attenuation by the patient and by the hardware in the x-ray beam (cassette, cassette holder, x-ray table) being ignored. Moreover, primary barrier calculations are done assuming a single, conservatively high value of the operating potential, rather than the lower kVp values more representative of clinical usage. This results in extreme conservatism, which is no longer defensible in light of the lowered dose limit to a member of the general public of 1 mSv y-1, which is equal in magnitude to natural background radiation (excluding radon). A shielding model is developed that accounts for attenuation of the primary beam prior to impinging on the structural barrier and which uses a workload which is distributed over a range of clinically realistic operating potentials. The resulting model is as simple to use as that, assuming a single value of the kVp. Sample calculations are performed and the results compared to those from more traditional shielding calculation methods.

Building Codes↗
PubMed2002

Tritium doses from chronic atmospheric releases: a new approach proposed for regulatory compliance.

Regulatory models for atmospheric releases of tritium approved by the Environmental Protection Agency (CAP88, AIRDOS-PC, and COMPLY) calculate doses only from tritiated water (HTO) taken into the body. They do not deal with dose from emissions of tritiated hydrogen gas (HT) and conversion of HT to HTO in the environment, nor do they address the dose from ingesting tritium incorporated into organic compounds. A simple model (NEWTRIT) is proposed that accounts for all pathways to dose from atmospheric releases of HT and HTO. The model is formulated in terms of the tritium-to-hydrogen ratio in each environmental compartment. With each transfer, a small reduction in the ratio is introduced to reflect the dilution that occurs in nature. Conversion of HT to HTO in the environment is modeled using the latest experimental data. Concentrations of organically bound tritium are calculated in foodstuffs based on amounts of hydrogen in proteins, fats, and carbohydrates. Concentrations in foodstuffs and doses calculated by NEWTRIT are consistent with the predictions of existing regulatory models. In addition, the HTO component of NEWTRIT is tested using public bioassay data and the HT component is tested using results from a model intercomparison study for a hypothetical HT release. Although tritium doses probably have not been underestimated by regulatory models that account only for HTO (due to the high degree of conservatism built into these models), the explicit treatment of HT and organically bound tritium proposed here will make the dose assessments more comprehensive, defensible, and scientifically acceptable. Because NEWTRIT includes all pathways to dose and predicts conservative doses, it is a suitable model to replace the tritium models currently used for compliance.

Air Pollutants, Radioactive↗
PubMed1983

Penetrating injuries of the neck: criteria for exploration.

One hundred thirty-six patients with penetrating injuries of the neck over a 4-year period were studied prospectively. Seventy-two patients (52.9%) had no major physical signs on admission, 56 were observed without complications, and 16 had a negative exploration. Injuries below the level of the cricoid cartilage were associated with a very high mortality (12.12%). We recommend a policy of selective conservatism in the management of penetrating neck injuries.

Brachial Plexus↗
PubMed1975

Hemangiomas of the parotid gland in children.

Twenty-six cases of parotid hemangiomas seen at the Montreal Children's Hospital are reviewed. This lesion is by far the most common tumor of the parotid gland in children. In recent years, our treatment of this condition has gradually shifted toward conservatism, reserving surgical excision for the unusual case where the lesion does no show spontaneous resolution.

Female↗
PubMed1990

Undetected diabetes and the plastic surgeon.

Plastic surgery candidates are generally healthy. Therefore, major postoperative complications are rare. Should they happen, the surgeon should search for possible causes, one of which is undetected diabetes mellitus. Six patients are presented who, based on the individual or family history or the unusual nature of their complications, were suspected of having diabetic tendencies. This experience necessitated our in-depth search into the role of silent or undetected diabetes. This report emphasizes the importance of positive family history of diabetes and the role of glucose tolerance tests on suspected cases. Even with normal glucose tolerance tests, however, some of these patients with a positive family history of diabetes and history of previous infections suffer from deficiencies in the chemotactic immune system. We recommend full discussion of the increased risk of infection and delayed healing with these patients, conservatism during surgical procedures, and prophylactic use of antibiotics perioperatively.

Aged↗
PubMed1999

Aesthetic rhinoplasty with maximum preservation of alar cartilages: experience with 52 consecutive cases.

Historically, rhinoplasty has been conceptualized mainly as an excisional and reductional operation of the nasal framework; however, there is growing evidence showing that conservatism in terms of preserving as much skeleton as possible makes the final results more predictable and more physiologic. On the basis of this point of view and using modifications of Tebbetts' technique, a prospective study of 52 patients presenting for primary open rhinoplasty was made. In all the cases, the cephalic portion of the lateral crus was preserved, and the procedure was designed basically to create a better anatomy from an aesthetic point of view. The results were evaluated aesthetically and by cephalometry, and patients showed improvement; native crura preservation was maximized. This report suggests more prospective studies need to be conducted to demonstrate the efficacy of these surgical variations on the average patient.

Adolescent↗
PubMedDate not supplied

Predictors of partner numbers in homosexual men: psychosocial factors in four societies.

Six hundred four homosexual men in four countries (Sweden, Finland, Australia, and the Republic of Ireland) were investigated with regard to their number of sexual partners over the past year and a number of psychological variables including masculinity and femininity, number of infections with sexually transmitted agents, relationships with parents, attitudes toward homosexuality, degree of homosexuality, sex-role conservatism, and a number of demographic variables. By use of multiple linear regression on partner numbers for each sample, it was found that between 15% and 28% of the variance of number of partners was accounted for by psychosocial factors, and that the great majority of these were significant in more than one country. Predictors included masculine and feminine personality traits, relationships with mother, degree of homosexuality, perceived societal attitudes toward homosexuality, age, and education. The data strongly suggest that psychosocial factors are significant predictors of numbers of partners of homosexual men, and that psychological approaches to treatment and prevention of sexually transmitted diseases may be warranted.

Adult↗
PubMed1995

Skin care for high-risk neonates.

Skin care for the high-risk neonate requires both knowledge of the unique aspects of the physiology of the integument of the neonate and awareness of potential complications. Practices that are useful in the prevention and treatment of skin complications among adults may be harmful when applied to neonates or young children. Although the focus of this article is on the neonate, iatrogenic complications have been reported in older children as well. Because a definitive age at which percutaneous absorption is no longer a risk is not known, it is best to err on the side of conservatism and apply these principles of neonatal skin care to the pediatric population at large.

Humans↗
PubMed2005

Occupational medicine practice in the United States since the industrial revolution.

OBJECTIVES: Occupational medicine lies at the interface between work and health. Not only do workplace hazards impact health, but our state of health influences our ability to get to work, to perform work, to tolerate work, and to gain a measure of satisfaction from the work we do. Comprehensive occupational medicine requires familiarity with the work that patients do; knowledge of the workplace itself and its hazards; appreciation of the social forces that shape work; and understanding of how chemical, physical, biologic, mechanical, and psychosocial agents influence health. Many practitioners who treat injured workers or provide disability assessments have no more formal training in occupational medicine than primary care physicians in general, which limits the quality, or at least the scope, of the care they give to workers. METHODS: This history has been compiled from books, journals, letters and recollections. A subset of journal issues from each decade after 1910 has been systematically reviewed, making no attempt to read through every issue. RESULTS: Industrial medicine as we recognize it began in the late-1800s, grew rapidly in the early and mid-1900s, and peaked toward the end of the 20th century, when American corporations began to outsource medical services, supporting the rise of free-standing industrial medicine facilities, chains of which now operate profitably throughout the country. Many of these facilities emphasize injury treatment, work hardening, and physical therapy rather than disease recognition and prevention. Occupational medicine is one of the very few medical specialties to be underserved. Board-certified specialists are relatively few, and when supply falls short of demand, the demand has tended to lower its sights. CONCLUSIONS: Occupational medicine has always been influenced by economics, politics, and changing patterns of employment, and today these forces include managed care, weakened unions, outsourcing and contract labor, and a generally growing political and social conservatism, not to mention multinational corporations. The globalization of manufacture and economics facilitated by rapid population growth in poor nations assures an unending supply of cheap labor, allowing limited attention to hazard control, thereby impeding progress in occupational health and safety. Some corporations are meeting the challenge of protecting their international workforce. Many, probably most, have not yet achieved this.

Certification↗
PubMed1993

The tuning of human photopigments may minimize red-green chromatic signals in natural conditions.

Humans and other Old World primates (Catarrhini) share very similar L (long-wavelength, 'red') and M (medium-wavelength, 'green') cone photopigment spectral sensitivities, with peaks at around 563 nm and 535 nm, respectively. Changes of single amino acid residues at critical sites in photopigment opsins can alter this peak tuning. Moreover, the photopigment alleles and spectral sensitivities of human populations are polymorphic, so there is potential for adaptive change or genetic drift. The manifest lack of variability suggests that the tuning of the L and M photopigments has adaptive significance, but the reason for this conservatism is unclear. To assess how natural spectral reflectances may have influenced pigment tuning, we have measured the chromatic (i.e. difference) signals available in natural scenes, and estimated how these signals would vary if spectral sensitivities of the pigments moved to longer or to shorter wavelengths. The size of the chromatic signal is, predictably, dependent principally on the spectral separation of the photopigments, but in addition we find that for a fixed separation there is a marked dependence on the specific peak tuning of the photopigments. Indeed, the naturally occurring L and M cone peaks may be set at a pair of points on the spectrum that on average minimizes the 'L-M' (i.e. red-green) chromatic signal. This somewhat paradoxical observation supports the view that red-green vision has evolved for a specific task, such as finding fruit, whilst minimizing interference by the chromatic signal in luminance vision to which both L and M cones contribute.

Adaptation, Physiological↗
PubMed1996

Colour vision as an adaptation to frugivory in primates.

Most mammals possess two classes of cone, sensitive to short and to long wavelengths of light, but Old World primates (Catarrhini) have distinct medium and long wavelength sensitive classes. The sensitivities of these cones photopigments are alike in all catarrhines with peaks at about 440 nm ('blue'), 533 nm ('green') and 565 nm ('red'). One possible reason for the evolution and conservatism of catarrhine trichromacy is that colour vision is a specialization for finding food. A model of retinal coding of natural spectra, based on discrimination thresholds, is used to examine the usefulness of dichromatic and trichromatic vision for finding fruit, and for identifying fruit and leaves by colour. For identification tasks the dichromat's eye is almost as good as a trichromat's, but the trichromat has an advantage for detecting fruit against a background of leaves.

Adaptation, Physiological↗
PubMed1998

Left-right asymmetry of fly wings and the evolution of body axes.

The body plan of Drosophila, and presumably that of other insects, develops under the control of anterio-posterior and dorsal ventral axes, but no evidence for a left-right axis has yet been found. We used geometric morphometrics to study the wings in three species of flies: Drosophila melanogaster, Musca domestica and Glossina palpalis gambiensis. In all three species, we found that both size and shape showed subtle, but statistically significant directional asymmetry. For size, these asymmetries were somewhat inconsistent within and between species, but for shape, highly significant directional asymmetry was found in all samples examined. These systematic left-right differences imply the existence of a left-right axis that conveys distinct positional identities to the wing imaginal discs on either body side. Hence, the wing discs of Drosophila may be a new model to study the developmental genetics of left-right asymmetry. The asymmetries of shape were similar among species, suggesting that directional asymmetry has been evolutionarily conserved since the three lineages diverged. We discuss the implications of this evolutionary conservatism in conjunction with results from earlier studies that showed a lack of genetic variation for directional asymmetry in Drosophila.

Animals↗
PubMed2004

Evolution of seasonal ecological niches in the Passerina buntings (Aves: Cardinalidae).

The evolution of migration has long been considered complex and recent work has demonstrated additional complexity: some species follow the same ecological conditions throughout the year, whereas others 'switch niches' between breeding and wintering ranges. Hypotheses regarding the evolution of migration would generally predict niche-following as primitive, and niche-switching as derived. However, no test has, to our knowledge, yet determined the directionality of evolution of these states within a lineage. We present an analysis of phylogenetic dimensions of seasonal niches in the Passerina buntings that indicates greater evolutionary change in the niches of breeding populations than among those of wintering populations. These results are consistent with hypotheses of (i) niche conservatism (in winter, at least) across a recently speciated lineage; and (ii) the derived state of the breeding (rather than winter) ecological niches of each species.

Animal Migration↗