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)     

Hydroxychloroquine: past, present, future

OBJECTIVE: To examine the trends in motor vehicle exhaust gas suicides since 1970 and to investigate the impact of catalytic converters. DESIGN: Australia-wide database analyses and a retrospective stratified series of 100 Victorian cases. DATA SOURCES: Australian Bureau of Statistics, 1970-1995; Australian Institute of Health and Welfare, National Injury Surveillance Unit, 1991/92-1995/96; Victorian Coroner's files, 1994-1996. RESULTS: There were 509 motor vehicle exhaust gas suicides in Australia in 1995, representing 22% of total suicides. Since the 1986 requirements for reduced carbon monoxide emissions from new vehicles (and thus the use of catalytic converters), the absolute numbers and rates of such suicides have increased, and they have come to represent a larger percentage of total suicides. Of 75 Victorian victims' vehicles traced, 36% were manufactured during or after 1986, showing that exhaust gas suicides have occurred in vehicles with catalytic converters. Blood carboxyhaemoglobin levels did not differ between victims using vehicles with or without catalytic converters. Between 1976 and 1991 exhaust gas suicides increased at a faster rate than motor vehicle registrations. Australian hospital admissions for exhaust gas suicide attempts have increased substantially since 1991-1992. CONCLUSION: Catalytic converters and the associated lower CO emission limits of 9.3 g/km had not, by 1995, resulted in a reduction in numbers, rates or percentages of exhaust gas suicides in Australia.     

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.     

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.     

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.     

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.     

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.     

Diabetes research in South Carolina: past, present, and future

Medical investigators in South Carolina have been on the "cutting edge" of diabetes research for a number of decades. Despite this fact, our state ranks second in the nation in diabetes prevalence, and diabetes complications are more severe here than anywhere else. It is from the efforts of these investigators that our hope for a brighter future comes. Through a concerted effort toward prevention, improvements in care, and investigation of the pathophysiology of diabetes and its complications, researchers may reduce the substantial burden of diabetes in our state and throughout the world.     

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.     

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.     

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.     

BSE in Northern Ireland: epidemiological patterns past, present and future

By 30 January 1998, there had been 170,259 confirmed cases of BSE in Great Britain (GB), 1766 confirmed cases in Northern Ireland (NI) (2 January 1998), and 276 confirmed cases in the Republic of Ireland (31 January 1998). Analysis of the epidemiological patterns in the NI epidemic reveals significant clustering of cases in herds and counties. The observed clustering of cases within herds results in lower per capita incidence of BSE in previously unaffected herds, providing support for the introduction of a certified herd scheme in NI. By fitting a backcalculation model to the case data, we can estimate the number of animals infected with the aetiological agent of BSE and project the number of future cases. We predict that the epidemic will decline rapidly, with approximately 99 cases (95% confidence interval 30,504) occurring in the five year period 1997-2001.