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Biomedical subjects

A D Lopez

Publications and source records attributed to A D Lopez.

At least 19 recordsLinked to original sources
PubMed1996

Mortality from smoking worldwide.

Estimates are made of the numbers and proportions of deaths attributable to smoking in 44 developed countries in 1990. In developed countries as a whole, tobacco was responsible for 24% of all male deaths and 7% of all female deaths, rising to over 40% in men in some former socialist economies and 17% in women in the USA. The average loss of life for all cigarette smokers was about 8 years and for those whose deaths were attributable to tobacco about 16 years. Trends in mortality attributable to tobacco differed between countries. In some the mortality in middle age (35-69 years) had decreased by half in men since 1965; in others it was continuing to increase. In women, the proportion was mostly increasing, almost universally in old age. Mortality not attributable to smoking decreased since 1955 in all OECD (Organization for European Collaboration and Development) countries, by up to 60% in men and more in women. No precise estimate can be made of the number of deaths attributable to smoking in undeveloped countries, but the prevalence of smoking suggests that it will be large. In the world as a whole, some 3 million deaths a year are estimated to be attributable to smoking, rising to 10 million a year in 30-40 years' time.

Adolescent↗
PubMed1996

The incremental effect of age-weighting on YLLs, YLDs, and DALYs: a response.

When disability-adjusted life years (DALYs) were first formulated, the effect of age-weighting on years of life lost due to death at each age as well as the different effect on short- and medium-term disability were taken into consideration. While there is considerable scope for discussion on the actual values that are incorporated into DALYs, the present article argues that once the values have been chosen we should accept the consequences of the choice.

Age Factors↗
PubMed1995

Growth factor/matrix-induced proliferation of human adult beta-cells.

Proliferation of human beta-cells in vitro is desirable for both transplantation and biological studies. In this study, human pancreatic islets obtained from cadavers were kept in tissue culture plates that favored cell attachment. When the cells attached to the matrix produced by the rat-bladder carcinoma cell line 804G, 5'-bromo-2'-deoxyuridine (BrdU) labeling increased from 4.7 +/- 2.5 to 13.2 +/- 2.2%, while cells simultaneously labeled for insulin and BrdU increased from 0 to 32%. Addition of the growth factor hepatocyte growth factor/scatter (HGF/SF) increased BrdU labeling to 17.5 +/- 1.8 and the percentage of double positive (BrdU + insulin) cells to 69%. This is the first in vitro demonstration that human beta-cells grown in monolayer culture are able to replicate when exposed to selected matrices and growth factors. These experiments add further evidence that HGF/SF is an important mitogenic agent for human beta-cells.

Adult↗
PubMed1994

At least one in seven cases of cancer is caused by smoking. Global estimates for 1985.

Tobacco smoking is accepted as a major cause of cancers of the lung, larynx, oral cavity and pharynx, oesophagus, pancreas, kidney and bladder. The proportions of these cancers that are due to smoking were estimated for the year 1985 for 24 areas of the world. Fifteen percent--1.1 million new cases per year--of all cancer cases are attributed to cigarette smoking, 25% in men and 4% in women. In developed countries, the tobacco burden is estimated at 16% of all annual incident cases. In developing countries, the corresponding figure is 10%. In total, 85% of the 676,000 cases of lung cancer in men are attributable to tobacco smoking. The highest attributable fractions (AF: 90-93%) are estimated in areas where the habit of cigarette smoking in men has been longest established: North America, Europe, Australia/New Zealand and the former USSR. Among the other 6 cancer sites considered in this analysis, those with the largest fractions of tobacco-related cases are the larynx, mouth and pharynx (excluding nasopharynx) and oesophagus. In regions where males have smoked for several decades, 30 to 40% of all cancers in this sex are attributable to tobacco. Unless tobacco-control efforts in developing countries are strengthened, the massive rise in cigarette consumption over the last few decades will produce a comparable rise in cancer in these countries within the next 20 to 30 years.

Adult↗
PubMed1994

Developmental gene expression in the human fetal pancreas.

Differential developmental regulation of pancreas-specific genes has not been reported for the human fetal pancreas. We have therefore undertaken a systematic, quantitative analysis of the transcriptional levels of various genes in the human pancreas at different stages of fetal and postnatal development. Using sensitive ribonuclease protection assays, in situ hybridization, and the polymerase chain reaction, our results indicate the following: 1) Transcriptional levels of insulin and amylin remain lower in the fetal than in the adult pancreas, whereas glucagon and somatostatin mRNA levels are consistently greater after 14 wk gestation than postnatally. These results are in agreement with previous immunohistochemical studies of these gene products. 2) The reg gene exhibits a 20-fold increase in mRNA levels after 16 wk gestation. The gene is expressed exclusively in the acinar cells and does not colocalize with insulin. This restricted exocrine expression does not indicate a direct role for the reg gene in islet development. 3) Glucose transporter 2 and glucokinase mRNA are detectable as early as 13 wk gestation and remain low throughout development. Glucose transporter 1 reaches adult transcriptional levels by 18 wk gestation. The early detection of glucose transporter 2 and glucokinase implies that lack of expression of these "glucose sensor" genes does not account for the known insensitivity of the fetal beta-cells to glucose.

Adult↗
PubMed1994

Hepatocyte growth factor/scatter factor has insulinotropic activity in human fetal pancreatic cells.

Fetal mesenchyme-derived factors are likely to play an important role in pancreatic islet development and growth. We have used primary cultures of human fetal pancreatic tissue to identify growth factors that have morphogenic, mitogenic, and insulinotropic activity. The formation of islet-like cell clusters (ICCs) during a 6-day culture was stimulated two- to threefold by hepatocyte growth factor/scatter factor (HGF/SF) basic fibroblast growth factor (FGF)-2, and to a lesser extent by keratinocyte growth factor (FGF-7) and insulin-like growth factor-II (IGF-II). In contrast, transforming growth factor-beta (TGF-beta) had a strong inhibitory effect. The ICCs formed during HGF/SF stimulation consisted mainly of epithelial cells, whereas FGF-2-induced ICCs were predominantly nonepithelial. Furthermore, although both FGF-2 and HGF/SF increased the total insulin content of the cultures, only HGF/SF increased the insulin content per DNA. Quantitatively, HGF/SF stimulated a 2.3-fold increase in the proportion of insulin-positive cells and a 3-fold higher number of replicating beta-cells. Blocking of the IGF-I receptor inhibited ICC formation but did not affect their insulin content. Immunoneutralizing TGF-beta resulted in increased cell growth and insulin content, indicating the presence of an endogenous inhibitory TGF-beta activity in the model system. Our results suggest that HGF/SF may be an important component of the fetal mesenchyme-derived factors responsible for pancreatic islet development. HGF/SF also may prove valuable for supporting the in vitro growth of islet cells.

Abortion, Legal↗
PubMed1994

Global and regional cause-of-death patterns in 1990.

Demographic estimation techniques suggest that worldwide about 50 million deaths occur each year, of which about 39 million are in the developing countries. In countries with adequate registration of vital statistics, the age at death and the cause can be reliably determined. Only about 30-35% of all deaths are captured by vital registration (excluding sample registration schemes); for the remainder, cause-of-death estimation procedures are required. Indirect methods which model the cause-of-death structure as a function of the level of mortality can provide reasonable estimates for broad cause-of-death groups. Such methods are generally unreliable for more specific causes. In this case, estimates can be constructed from community-level mortality surveillance systems or from epidemiological evidence on specific diseases. Some check on the plausibility of the estimates is possible in view of the hierarchical structure of cause-of-death lists and the well-known age-specific patterns of diseases and injuries. The results of applying these methods to estimate the cause of death for over 120 diseases or injuries, by age, sex and region, are described. The estimates have been derived in order to calculate the years of life lost due to premature death, one of the two components of overall disability-adjusted life years (DALYs) calculated for the 1993 World development report. Previous attempts at cause-of-death estimation have been limited to a few diseases only, with little age-specific detail. The estimates reported in detail here should serve as a useful reference for further public health research to support the determination of health sector priorities.

Adolescent↗
PubMed1994

Quantifying disability: data, methods and results.

Conventional methods for collecting, analysing and disseminating data and information on disability in populations have relied on cross-sectional censuses and surveys which measure prevalence in a given period. While this may be relevant for defining the extent and demographic pattern of disabilities in a population, and thus indicating the need for rehabilitative services, prevention requires detailed information on the underlying diseases and injuries that cause disabilities. The Global Burden of Disease methodology described in this paper provides a mechanism for quantifying the health consequences of the years of life lived with disabilities by first estimating the age-sex-specific incidence rates of underlying conditions, and then mapping these to a single disability index which collectively reflects the probability of progressing to a disability, the duration of life lived with the disability, and the approximate severity of the disability in terms of activity restriction. Detailed estimates of the number of disability-adjusted life years (DALYs) lived are provided in this paper, for eight geographical regions. The results should be useful to those concerned with planning health services for the disabled and, more particularly, with determining policies to prevent the underlying conditions which give rise to serious disabling sequelae.

Adolescent↗
PubMed1994

The global burden of disease in 1990: summary results, sensitivity analysis and future directions.

A basic requirement for evaluating the cost-effectiveness of health interventions is a comprehensive assessment of the amount of ill health (premature death and disability) attributable to specific diseases and injuries. A new indicator, the number of disability-adjusted life years (DALYs), was developed to assess the burden of disease and injury in 1990 for over 100 causes by age, sex and region. The DALY concept provides an integrative, comprehensive methodology to capture the entire amount of ill health which will, on average, be incurred during one's lifetime because of new cases of disease and injury in 1990. It differs in many respects from previous attempts at global and regional health situation assessment which have typically been much less comprehensive in scope, less detailed, and limited to a handful of causes. This paper summarizes the DALY estimates for 1990 by cause, age, sex and region. For the first time, those responsible for deciding priorities in the health sector have access to a disaggregated set of estimates which, in addition to facilitating cost-effectiveness analysis, can be used to monitor global and regional health progress for over a hundred conditions. The paper also shows how the estimates depend on particular values of the parameters involved in the calculation.

Adolescent↗
PubMed1993

Maturation and function of human fetal pancreatic cells after cryopreservation.

If transplantation of endocrine tissue is to become a therapy for a significant number of insulin-dependent diabetic individuals, tissue sources other than adult human islets will be required. Because human fetal pancreatic cells may offer that alternative, we have tried to find the optimal combination of tissue culture and cryopreservation methods for use in transplantation. Islet-like cell clusters (ICCs), cryopreserved according to reported methods for adult human islets, survived poorly after thawing. In contrast, the yield of ICCs was comparable after collagenase digestion of fresh and cryopreserved pancreatic fragments. However, the ICCs derived from cryopreserved tissue contained a higher proportion of nonepithelial cells, and the recovery of insulin was only 28%, as compared with freshly cultured cells. These ICCs had a lower DNA content and a higher rate of DNA synthesis. Moreover, cryopreserved cells released a higher fraction of their insulin content in basal conditions, and their response to theophylline stimulation was slightly lower. ICCs generated from cryopreserved fragments were able to mature morphologically and functionally in vivo after transplantation into athymic nude mice. However, the level and magnitude of the C-peptide response did not equal that of grafted freshly cultured ICCs. Our results indicate that it is possible to generate ICCs from cryopreserved human fetal pancreas with the capacity, after transplantation, to release insulin appropriately in response to glucose. However, possibly because undifferentiated pancreatic cells may be particularly vulnerable to cryopreservation, current methods may need to be improved for optimal tissue retrieval.

Animals↗
PubMed1993

Tobacco or health.

Tobacco smoking is the major cause of premature death among men in the CCEE/NIS. Reliable information on smoking prevalence and tobacco use is scarce, but the overall evidence points to two different patterns: a traditional and a high prevalence pattern. The traditional pattern dominates in the NIS and some of the CCEE, and is characterized by a high smoking rate in men (about 50%) and a low rate in women (10%). Smoking by women, however, is increasing, starting with the younger age groups. The high prevalence pattern found in the Czech Republic, Hungary and Poland, for example, shows a high smoking prevalence in women (about 25%) in addition to a high prevalence in men. Predictions made in 1990 indicated further increases or stable tobacco consumption in the CCEE/NIS by the year 2000, in contrast with the steady decrease in western European countries. When smoking is combined with other types of harmful health behaviour and environmental influences, the result is some of the highest mortality rates from lung cancer and other diseases in the world. This situation has caused severe concern in public health professionals in many of the affected countries, but not in the public and policy-makers. The fundamental changes in social and economic structures have both improved and decreased opportunities to promote nonsmoking. In the short term, the negative influences seem to dominate, although some countries, such as Lithuania and Poland, are now introducing their first realistic policies on tobacco. In most countries, however, tobacco control has to compete with other issues for priority on a crowded public health agenda.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Assessing the burden of mortality from cardiovascular diseases.

The present estimate of global mortality caused by cardiovascular diseases is accompanied by a considerable degree of uncertainty, which, in so far as monitoring their emergence in developing countries is concerned, undoubtedly represents one of the major obstacles to effective public health interventions for their control. In much of the developing world, vital registration data are lacking and it would be unreasonable to expect rapid progress in the recording of causes of death because resources are so limited. The most promising avenue is that of the progressive implementation of clearly defined mortality surveillance systems that cover all deaths and permit the attribution of probable causes via lay reporting. The reliability of the data largely depends on the specificity and clarity of the verbal autopsy algorithm employed and on the availability of medically trained personnel to validate the returns.

Cardiovascular Diseases↗
PubMed1992

Mortality from tobacco in developed countries: indirect estimation from national vital statistics.

Prolonged cigarette smoking causes even more deaths from other diseases than from lung cancer. In developed countries, the absolute age-sex-specific lung cancer rates can be used to indicate the approximate proportions due to tobacco of deaths not only from lung cancer itself but also, indirectly, from vascular disease and from various other categories of disease. Even in the absence of direct information on smoking histories, therefore, national mortality from tobacco can be estimated approximately just from the disease mortality statistics that are available from all major developed countries for about 1985 (and for 1975 and so, by extrapolation, for 1995). The relation between the absolute excess of lung cancer and the proportional excess of other diseases can only be approximate, and so as not to overestimate the effects of tobacco it has been taken to be only half that suggested by a recent large prospective study of smoking and death among one million Americans. Application of such methods indicates that, in developed countries alone, annual deaths from smoking number about 0.9 million in 1965, 1.3 million in 1975, 1.7 million in 1985, and 2.1 million in 1995 (and hence about 21 million in the decade 1990-99: 5-6 million European Community, 5-6 million USA, 5 million former USSR, 3 million Eastern and other Europe, and 2 million elsewhere, [ie, Australia, Canada, Japan, and New Zealand]). More than half these deaths will be at 35-69 years of age: during the 1990s tobacco will in developed countries cause about 30% of all deaths at 35-69 (making it the largest single cause of premature death) plus about 14% of all at older ages. Those killed at older ages are on average already almost 80 years old, however, and might have died soon anyway, but those killed by tobacco at 35-69 lose an average of about 23 years of life. At present just under 20% of all deaths in developed countries are attributed to tobacco, but this percentage is still rising, suggesting that on current smoking patterns just over 20% of those now living in developed countries will eventually be killed by tobacco (ie, about a quarter of a billion, out of a current total population of just under one and a quarter billion).

Adult↗