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PubMed1992

Chemicals classified by IARC: their potency in tests for carcinogenicity in rodents and their genotoxicity and acute toxicity.

Chemicals classified by the IARC to its groups 1, 2A, 2B and 3 were examined in an attempt to identify characteristics of their behaviour in experimental studies of carcinogenicity, genotoxicity and acute mammalian toxicity that correlate with those categories. Only those agents for which information on carcinogenic potency was available were studied. In both mice and rats, more chemicals were potent carcinogens if they had been categorized in Group 1 (human carcinogens) than if they had been put into one of the other categories. Not surprisingly, there was a weak association between carcinogenic potency and acute toxicity. Mice were especially sensitive to tumour induction by halides; the lower sensitivity of rats to any carcinogenic effect of halides could be due in part to their higher systemic toxicity in this species: a reduced differential of toxic and carcinogenic doses decreases the dose window in which carcinogenic effects may be demonstrated. It was notable that the human carcinogens were active in those genotoxicity tests with higher specificity for identifying rodent carcinogens. Predictive assays for carcinogenicity that were considered to be highly specific were tests for cytogenetic effects in vivo, unscheduled DNA synthesis in hepatocytes, mutation in any of the five commonly used strains of Salmonella typhimurium and mutation at the hprt locus in mammalian cells. None of the relationships was strong enough to form the basis of a simple categorization, but they could serve to alert investigators to chemicals of special toxicological interest and importance.

Animals↗
PubMed1992

Chemical toxicity and chemical carcinogenesis. Is there a causal connection? A comparative morphological evaluation of 1500 experiments.

Chemicals cause toxic and carcinogenic effects as well as beneficial and other adverse effects in animals and in humans. The purpose of this paper is to assess whether there is a direct, uniform causal relationship between toxicity and carcinogenicity. Within this context, specific issues receive attention: the influence of exposure concentrations on carcinogenesis; kidney cancer and alpha 2 mu-globulin; urinary calculi and tumours; and cell turnover or proliferation and cancer. The data used to evaluate histopathological site-specific correspondence between these two end-points comes from 130 studies of chemical carcinogenesis designed and conducted by the US National Toxicology Program (NTP). Nearly 1500 sex-species-exposure group experiments were evaluated for morphological evidence of toxicity and/or carcinogenicity, for dose-response relationships, and for site-specific correlations of toxicity and carcinogenicity. The major conclusions are that chemicals evaluated for long-term toxicity and carcinogenicity in experimental animals can be divided into three categories: (1) those that cause organ toxicity without cancer, (2) those that cause site-specific cancer with no associated toxicity and (3) those that cause toxicity and cancer in the same organ. Examples are given to illustrate each category. On the basis of this comparative analysis, in the great majority of cases the available data do not support a correlation between chemically induced toxicity and carcinogenicity. Moreover, until considerably more scientific knowledge about molecular mechanisms of carcinogenesis becomes available and accepted, attempts to use findings on toxicity to modify the risk assessment process will be fraught with uncertainty and might even have a negative impact on public health.

Animals↗
PubMed1992

Overall safety of Arthrotec.

Data from four double-blind studies of the treatment of patients with rheumatoid arthritis or osteoarthritis were combined. For 4 to 12 weeks, 747 patients received Arthrotec, a combination of 50 mg of diclofenac and 200 micrograms of misoprostol, and 754 patients received 50 mg of diclofenac; the drugs were given twice or three times daily. The five most commonly reported adverse events were abdominal pain by 23.2% of the diclofenac/misoprostol patients and 19.8% of the diclofenac patients; diarrhea by 19.9% and 11.3%; nausea by 11.8% and 6.5%; dyspepsia by 11.2% and 7.8%; and flatulence by 8.0% and 3.1%. Other adverse events, reported by similar proportions of both treatment groups, included headache, gastritis, dizziness, vomiting, and constipation. In the diclofenac/misoprostol-treated patients, the abdominal pain and diarrhea were rated mild in 30.6% and 24.3%, moderate in 49.1% and 51.4%, and severe in 20.2% and 24.3%. Serious adverse events occurred in eight of the diclofenac/misoprostol-treated patients and in 13 of the diclofenac-treated patients; 12.6% and 10.1%, respectively, were withdrawn from the study because of adverse events. Results of laboratory tests of hepatic and renal function were similar in the two treatment groups.

Administration, Oral↗
PubMed1992

Apparent lack of synergism between heparin and dihydroergotamine in prevention of deep vein thrombosis after elective hip replacement: a randomised double-blind trial reported in conjunction with an overview of previous results.

We report the results of a double-blind, randomised trial of venous thrombosis (VT) prevention in 117 patients having elective hip replacement where low dose heparin alone (5,000 IU sodium heparin given subcutaneously [sc] 8 hourly until the seventh postoperative day) was compared with low dose heparin plus dihydroergotamine (DHE; 0.5 mg, given 8 hourly by sc injection). The trial end point consisted of VT discovered through bilateral ascending venography done routinely on the seventh postoperative day. VT developed in 34% of patients given heparin/DHE (95% confidence interval = 22% - 47%) compared with 24% in those given low dose heparin alone (95% confidence interval = 14% - 37%; p = 0.34), difference = 10% (95% confidence interval = -7% to +26%). Corresponding figures for the incidence of proximal (above-knee) thrombosis were 17% and 14% (95% confidence intervals = 8% - 29% and 6% - 25% respectively). These results are discussed in the context of a detailed overview of published evidence concerning VT prevention with heparin/DHE after hip replacement and we conclude it is unlikely that heparin/DHE is markedly superior to low dose heparin alone in this clinical setting.

Aged↗
PubMedDate not supplied

[3 years of "new developments" in pharmacotherapy. An update which is also a proposal for participative experimentation].

The analysis of the contents of key national and international drug bulletins provides a comprehensive overview of what has been produced worldwide in the field of pharmacology and therapeutics over the last few years after the last publication in R d 1). The work presented, tries to avoid the risk of being a purely descriptive listing of true and false "new" information, and may be seen as an "experiment of information transfer": the available data are presented and summarised from various complementary points of view, to suggest also a methodology of permanent education, for which instruments are also proposed. Further, the text is tentatively proposed as an experiment of communication between nurses and pharmacists, to stimulate their dialogue and interaction both with respect to the use of drug literature and to the evaluation of daily needs of information in routine hospital practice.

Drug Therapy↗
PubMed1992

[Perioperative blood transfusion and prognosis in colorectal cancer. Analysis of a series].

The relationship between survival after surgical resection of colorectal carcinoma, and perioperative blood transfusion was studied retrospectively. "Curative" surgery was performed in 164 cases of colorectal cancer--stages B and C--, 72 of them received red-cell concentrates perioperatively. Multiple regression analysis did not show any deleterious effect of blood transfusion on the survival of the surgically treated patients (P = 0.941). The volume of the blood derivative received neither seems to influence their outlook. As it was expected a higher rate of transfusion occurred among rectal cancer patients. Mechanisms and factors involved in this controverted issue are discussed and literature is widely reviewed.

Actuarial Analysis↗
PubMedDate not supplied

[Gasometric values reported in healthy subjects from the Mexican population: review and analysis].

We do not know the normal relationship between altitude and PaCO2 in Mexico. We collected and analyzed the reports of reference values for gasometry in Mexico City (2240 m above sea level and a mean barometric pressure of 585 Torr) and other places in the country. The reports include arterial, capillary and expired gases in children and adults, with measurements done in resting and exercising subjects, breathing room air and 100% oxygen. In Mexico City we found 18 studies in normal subjects reporting a mean PaCO2 ranging from 25.5 to 38.4 Torr. Averaging arterial studies from children and adults, adjusting for the number of subjects studied, and discarding data with mean pH below 7.37 or above 7.43 (suggesting non steady state), 10 studies with a total of 581 subjects have the following average values (Torr, means and SD): PaCO2 = 31.1 +/- 2.6, PaO2 = 67.7 +/- 2.6, calculated PAO2 and P(A-a)O2 73.6 +/- 3.3 y 6.1 +/- 3.7 respectively. The PaCO2 found was much lower than that reported for native Peruvians in the Andes who have a mean PaCO2 of 37.8 Torr at an altitude of 2390 m, and a mean PaCO2 of 33.0 Torr only at 4860 m above the sea level. On the other hand, the average values in Mexico are similar to those found in North Americans who have a mean PACO2 of 33.1 Torr at 2131 m of altitude, a mean PACO2 of 30.7 at 2371 m and a mean PaCO2 of 31 Torr at 2238 m. Normal values for gasometry in Mexico are scarce and some of the existing ones are erroneous probably due to lack of adequate calibrations and to poor quality control. Values of PaCO2 in Mexico are more similar to those found in the USA than to those found in Peruvian natives.

Adaptation, Physiological↗
PubMedDate not supplied

[Diagnostic performance of immunologic tests in amebic liver abscess using receiver operating characteristic curves].

Objectives. 1) To identify the tests of immunological diagnosis with a high diagnostic efficiency in amebic liver abscess. 2) To determine the ideal cutoff point for such tests. 3) To identify the influence degree of the antigen used over the test efficiency. Design. Comparative survey. Study units. Analysis of 24 articles identified in the medical literature about tests of immunological diagnosis in amebic liver abscess. Measurements. Starting from the articles, operating characteristics curves (ROC) were established derived from the test application to patients with amebic liver abscess. Results. A great variability in the diagnostic efficiency was identified between the various tests, even when the analysis was focused on the investigations of a specific test. It was not possible to conclude which test had a major degree of efficiency due to such variability. The cutoff level considered as relevant was higher than the one traditionally used for indirect hemagglutination and it had concordance with the one presently accepted for the fluorescence antibodies test. By maintaining steady the spectrum of the study patients and the type of test, variability among the tests persisted. This was due to the use of different antigens. Conclusions. A great variation in the diagnostic efficiency of the analyzed tests was identified. The variation source was the type of test, the antigen used and probably the illness spectrum.

Evaluation Studies as Topic↗
PubMed1992

[Effectiveness of psychosocial management of cancer patients--a critical review of empirical studies (status: December 1990)].

41 empirical studies evaluating psychosocial care of cancer patients, published between 1975 and 1990 are presented. Only those studies were selected that examined adult patients and controlled the effects of psychotherapeutic interventions. 35 studies reported significant effects on coping, mood states or quality of life. 6 articles were inquiries into the efficiency of intervention on time of survival, 3 measured the impact on the immune system.

Adaptation, Psychological↗
PubMed1992

The impact of stopping rules on heterogeneity of results in overviews of clinical trials.

This paper explores the extent to which application of statistical stopping rules in clinical trials can create an artificial heterogeneity of treatment effects in overviews (meta-analyses) of related trials. For illustration, we concentrate on overviews of identically designed group sequential trials, using either fixed nominal or O'Brien and Fleming two-sided boundaries. Some analytic results are obtained for two-group designs and simulation studies are otherwise used, with the following overall findings. The use of stopping rules leads to biased estimates of treatment effect so that the assessment of heterogeneity of results in an overview of trials, some of which have used stopping rules, is confounded by this bias. If the true treatment effect being studied is small, as is often the case, then artificial heterogeneity is introduced, thus increasing the Type I error rate in the test of homogeneity. This could lead to erroneous use of a random effects model, producing exaggerated estimates and confidence intervals. However, if the true mean effect is large, then between-trial heterogeneity may be underestimated. When undertaking or interpreting overviews, one should ascertain whether stopping rules have been used (either formally or informally) and should consider whether their use might account for any heterogeneity found.

Analysis of Variance↗