Asbestos: past, present and future

Owing to its particular properties asbestos has been widely used for the production of insulating material, for fire proofing, and for strengthening to other materials such as cements and plastics, and thus the story of this mineral was one of progressive commercial success until the middle of this century. However, serious health hazards were realized early: around the turn of the century a progressive form of diffuse fibrosis (asbestosis) in asbestos workers was observed and in 1950 an excess risk of lung cancer, while in 1960 the causal relationship between asbestos and mesothelioma were confirmed. In view of the known potential risks of asbestos and its widespread use in the building industry, more recently asbestos has caused considerable public concern and anxiety. Based on numerous experimental and epidemiological observations, present knowledge of the pathogenic effects of asbestos is sufficient for a number of broad conclusions to be drawn. (1) The amphibole types of asbestos are too dangerous for use as industrial material, and should be banned. (2) Chrysotile can probably be used safely if there is strict control of the workers' dust exposure. (3) It is very unlikely that the general public is at any measurable risk from asbestos in buildings. Exceptions are people working regularly on maintenance tasks involving removing or cutting of asbestos in buildings; such people are properly classified as asbestos workers and should be protected accordingly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cancer prevention: past, present, future

There are many examples of different types of cancers that have been prevented by appropriate measures in the past. Most of them were related to occupational, iatrogenic or accidental factors, often as the outcome of heavy exposure of humans to specific carcinogenic agents. Cancer is a disease of DNA, and is generally associated with multiple genetic alterations, these being produced in the typical case by exposure to various carcinogens, each of which exists at minute concentrations. Thus, the impact of carcinogenic factors, xenobiotics and autobiotics, is due to their actions in concert. However, a single mutation yielding genomic instability exerts a disproportionately large influence by resulting in a large number of secondary mutational events. Epigenetic changes can also not be disregarded especially from the view point of prevention of neoplasia. The occurrence of multiple primary cancers among survivors of initial primaries, and the presence of hereditary groups with a high risk of cancer development provide a strong stimulus for establishment of effective approach for cancer prevention, which should be, in principle, multi-faceted. Therefore, a holistic approach is essential with improvement in life style including choosing a balanced diet and avoidance of cigarette smoking and other sources of carcinogens, as integral elements.     

Pubovaginal slings: past, present and future

Renewed interest in the pubovaginal sling procedure for stress urinary incontinence has occurred in response to recent reports of poor durability and inconsistent efficacy associated with simple cystourethropexy. Many of the failures are felt to represent patients with an unrecognized component of intrinsic sphincteric deficiency. Historically slings have a favourable cure rate, but have been perceived as having unacceptably high rates of prolonged urinary retention and secondary detrusor instability. This article reviews the preoperative evaluation and indications for pubovaginal slings, describes the evolution of the current techniques, and discusses choice of sling material, surgical approach, results and complications. It is hoped that this review will stimulate interest in this versatile but technically challenging procedure.     

Defining epileptogenic foci: past, present, future

There is a direct relationship between the geometry (location, area, and orientation) of cortex-generating epileptiform discharges and resultant spike or seizure voltage fields at the scalp. Epileptogenic foci have been localized traditionally with EEG by identifying the negative field maximum (e.g., a phase reversal between adjacent bipolar channels). However, it is the shape of the entire voltage field over the head, including both negative and positive maxima, which provides information necessary to characterize the focus properly. Source location and orientation can be inferred from spike or seizure voltage topography, however, three-dimensional visualization can be obtained from mathematical source models, such as an equivalent dipole. Recent investigations have shown that dipole models can identify the location of epileptogenic foci with sub-lobar precision. Accuracy is enhanced by using additional electrodes, particularly on the lower half of the head, and by measuring their location. Realistic head models obtained from three-dimensional reconstructions of MR images can overcome errors introduced by simple spherical models of the cranium. Co-registering EEG voltage topography and source models with a patient's own cerebral anatomy will make EEG an unparalleled functional imaging technique for defining epileptogenic foci.     

Medicare managed care: past, present, and future

Medicare managed care enrollment has mushroomed in the past few years, tripling from 1993 to 1997. The payment rates have allowed plans to offer valuable extra benefits to beneficiaries at little or no additional cost; employers have provided inducements for their retirees to enroll; and many of the new Medicare beneficiaries are already in managed care plans when they enter the program. The Balanced Budget Act of 1997 and other factors could cause enrollment trends to change in either direction. More kinds of plans, including physician service organizations and preferred provider organizations, may be more attractive; new educational efforts may make more beneficiaries aware of managed care plans; and employers may continue to move their retirees into managed care. On the other hand, lower than expected Medicare payment rates to the plans may reduce the additional benefits they offer; consumer dissatisfaction with managed care is growing; and employers are dropping retiree benefits altogether. The future of Medicare managed care is hard to predict.     

Pertussis vaccines: past, present and future in Australia

In August 1997, a workshop was convened by the National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases to consider current issues in the use of pertussis vaccines and implications for the Australian immunisation schedule. Topics covered included the history, efficacy and reactogenicity of whole-cell and acellular vaccines and vaccine schedules. Acellular pertussis vaccine is preferred by the National Health and Medical Research Council for the primary course as well as the 18 month and 4-5 year old childhood doses. At the time of the workshop, a 3-component acellular vaccine (DTPa) had been approved (licensed) in Australia for all doses in the childhood schedule. It was the first vaccine subject to a cost-effectiveness evaluation under the new vaccine funding arrangements. Issues considered in the evaluation of the cost-effectiveness of the vaccine were discussed. These included comparative efficacy, adverse events and compliance, and the question of community as well as individual benefit from the use of the vaccine.     

Accuracy of anthropometric measurements: past, present, and future

Experience, based on anthropometric examination of over 1000 children with facial syndromes and more than 2400 healthy subjects of both sexes and various ages, has led me to diverge in some points from the more usual views found in the physical anthropologic literature. The purpose of this paper is to discuss the major controversial topics associated with anthropometric measurement. These include the problems associated with formation of a representative population sample, the relative validity of longitudinal and cross-sectional studies, the interpretation of intraobserver and interobserver testings, and the questionable judgments of mensurative skill in clinical practice. The factors influencing the accuracy of anthropometric measurements, definitions of both the consistent and less reliable measurements, and the duration of validity of anthropometric normative data are also discussed.     

Evolution of transitional care settings: past, present, future

The use of intravascular stents as an adjunct for percutaneous transluminal revascularization is limited by two principal factors, acute thrombosis and neointimal proliferation, resulting in restenosis. To overcome these limitations, we have investigated the potential of microporous bioresorbable polymer stents formed from poly(L-lactic acid) (PLLA)/poly(epsilon-caprolactone) (PCL) blends to function both to provide mechanical support and as reservoirs for local delivery of therapeutic molecules and particles to the vessel wall. Tubular PLLA/PCL stents were fabricated by the flotation-precipitation method, and helical stents were produced by a casting/winding technique. Hybrid structures in which a tubular sheath is deposited on a helical skeleton were also generated. Using a two-stage solvent swelling technique, polyethylene oxide has been incorporated into these stents to improve hydrophilicity and water uptake, and to facilitate the ability of these devices to function as drug carriers. Stents modified in this manner retain axial and radial mechanical strength sufficient to stabilize the vessel wall against elastic recoil caused by vasoconstrictive and mechanical forces. Because of the potential of direct gene transfer into the vessel wall to ameliorate thrombosis and neointimal proliferation, we have investigated the capacity of these polymer stents to function in the delivery of recombinant adenovirus vectors to the vessel wall. In vitro, virus stock was observed to readily absorb into, and elute from these devices in an infectious form, with suitable kinetics. Successful gene transfer and expression has been demonstrated following implantation of polymer stents impregnated with a recombinant adenovirus carrying a nuclear-localizing betaGal reporter gene into rabbit carotid arteries. These studies suggest that surface-modified polymer stents may ultimately be useful adjunctive devices for both mechanical support and gene transfer during percutaneous transluminal revascularization.     

Laboratory diagnosis of tuberculosis: past, present, and future

Resurgence of tuberculosis justifies extraordinary efforts to expedite TB diagnosis and susceptibility testing. This demands that laboratory support expand to a "second generation" of methods and procedures, including rapid availability of fluorochrome smears of concentrated specimens, faster techniques for detection (e.g., the BACTEC radiometric broth system and microcolony detection), quicker identification (e.g., high-pressure liquid chromatography, nonisotopic genetic probes), more rapid susceptibility testing methods (e.g., BACTEC), and reporting of these results as critical values. Guidelines have been established for turnaround time for results of smears, TB organism identification, and susceptibility testing to usual first-line drugs. A "third generation" of laboratory techniques soon will make testing not only more effective but also more efficient. These methods include direct testing of respiratory specimens through nonisotopic genetic probes as well as nucleic acid amplification techniques utilizing polymerase chain reaction (PCR) and other molecular procedures. These new procedures and protocols place heavy demands on laboratory test volume, technologist time and costs. For the healthcare system or clinical laboratory without the resources to deal with these new demands, referral of TB specimens represents a reasonable alternative, as long as transport is adequate to meet current CDC and other guidelines for turnaround time.     

Non-insulin dependent diabetes--the past, present and future

The aim of this investigation was to establish a new model for phototoxicity which is more advanced than the widely used cultures of yeasts, bacteria or cells of various origin, and at the same time to avoid animal testing. We studied the extraembryonal vasculature of the incubated hen's egg. This model was originally introduced by toxicologists as an alternative to the rabbit's eye irritation test (Draize test). In the photo hen's egg test, substances are applied to the embryo's yolk-sac blood vessel system at a non-toxic concentration and are irradiated with 5 J/cm2 ultraviolet A (UVA) (320-400 nm). Promethazine, haematoporphyrin, ciprofloxacin and 8-methoxypsoralen were tested in this system. Death of the embryo, membrane discoloration and haemorrhage are parameters for phototoxic damage, which were recorded during an observation period of 24 h. These well-known phototoxic substances induced pronounced damage of the yolk-sac membrane and blood vessels which was not found in the controls (test substance alone, UVA alone or untreated) using a 2 x 2 factorial test design. The photo hen's egg test serves as a valid screening model for substances supposed to be photosensitizers owing to a phototoxic mechanism.     

Air-atomized iron powders — past, present, future

This article examines the history and future prospects of the production of iron powders by the atomizing high-carbon melts with compressed air. In terms of their properties, the iron powders obtained by this method are intermediate between water-atomized powders and reduced powders. They can be used to make anti-friction products or structural elements having a density within the range 6.3–6.9 g/cm³. The outlook for these powders is promising in Russia because they are needed for machine construction, especially in the auto industry.     

The genetics of schizophrenia: past, present, and future concepts

Although a genetic susceptibility for schizophrenia has been long established and even noted by Kraepelin in 1907, the mechanisms for its inheritance remains unknown. No candidates have proven to be correct and while many weakly positive chromosomal linkages have been reported, none have yet been consistently replicated. The following review examines the present status of these findings. The conclusion is that the field must move on to finding a consistently replicable mutation segregating with schizophrenia in families, before any of the present linkage results can be resolved.     

The ethnicity gap: The past, present, and future.

The gap between the growth of ethnic minority groups nationally and the numbers of such groups within psychology is described. Three topics relevant to professional psychology are considered: mental health services, the educational pipeline, and the governance structure within the American Psychological Association. The authors outline past and current data and recommend actions for the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of neurosurgery in Greece: past, present, and future

In this study the authors examine the historical tradition as well as current features of neurosurgery in Greece and compare the available data with international standards. In particular, they describe the organizational structure of neurosurgery with reference to manpower, unit distribution, training, and qualification. They discuss problems such as overproduction of neurosurgeons and the poor control of training and qualification procedures in the neurosurgical profession. The findings are examined in a critical way and solutions are proposed that could improve the present situation.     

Murine natural killer cell differentiation: past, present, and future

Natural killer cells are bone marrow-derived lymphocytes capable of lysing a variety of target cells without prior exposure. While the biological activities and function of mature NK cells have been extensively investigated, the differentiation of NK cells from primitive hematopoietic stem cells is poorly understood. Recently, we have reported on the identification of a highly enriched bone marrow population capable of repopulating recipient mice with mature NK cells. In this review, we will summarize our findings and those of others in an attempt to clarify the current status of murine natural killer cell differentiation.     

Geriatric psychiatry subspecialization in Canada: past, present, and future

We evaluated the clinical data in 83 patients with sepsis, which was diagnosed by both Bone's definition of sepsis and positive isolates from blood culture, according to their underlying diseases. This study enrolled a total of 117 septic episodes in 83 patients (57 males and 26 females, mean age: 52.0 years). We classified 3 groups, including hematological malignancies (46 patients, 72 episodes), solid malignant tumors (23 patients, 25 episodes) and non-malignancies (14 patients, 20 episodes), by the underlying diseases. Of the total number of isolates from blood culture, 53.0% were single gram-positive bacteria, 33.3% were single gram-negative bacteria, 7.7% were single fungus and 6.0% were polymicrobial organisms. In addition, coagulase negative staphylococci was isolated most often in patients with hematological malignancies. Sepsis was often caused by infectious focuses of hemorrhoid, stomatitis or intravenous catheter in patients with hematological malignancies, by pneumonia in patients with solid malignant tumors and by urinary tract infection in patients with non-malignancies. Mortality of sepsis in patients with solid malignant tumors (48%) was highest in 3 groups. Septic patients, who were complicated with shock and/or DIC, has poor prognosis in all groups. Serum albumin level was significantly lower in dead patients than patients who survived. These results suggest that clinical features may be different according to the underlying diseases of patients with sepsis.