Developmentally regulated expression of a truncated myosin light-chain 1F/3F gene.

Fast skeletal muscle myosin light-chain I (MLC1f) and myosin light-chain 3 (MLC3f) mRNAs are both derived from a single rat MLC1/3f gene. MLC1f mRNA begins at the first exon of the gene, while MLC3f mRNA begins with exon 2, 10 kilobases downstream. Both mRNAs require alternate splicing of internal exons for accurate expression. We showed that a truncated rat MLC1f/3f gene lacking exon 1 and the first 6.3 kilobases of the intron separating exons 1 and 2 produced rat MLC3f mRNA in a developmentally regulated manner after introduction into myogenic mouse cells, thus demonstrating in vivo the presence of a functional promoter associated with exon 2. Correctly spliced mRNA was produced after transfer of this truncated gene into both myogenic and nonmyogenic cells, indicating that the pattern of splicing of this complex transcript was due to a structural features of the RNA and was independent of cell type.

Time trends in lung cancer mortality among nonsmokers and a note on passive smoking.

Lung cancer mortality rates were computed for nonsmokers in the American Cancer Society's prospective study for three 4-year periods from 1960 to 1972 and in the Dorn study of veterans for three 5-year periods from 1954 to 1969. There was no evidence of any trend in these rates by 5-year age groups or for the total groups. No time trend was observed in nonsmokers for cancers of other selected sites except for a decrease in cancer of the uterus. Compared to nonsmoking women married to nonsmoking husbands, nonsmokers married to smoking husbands showed very little, if any, increased risk of lung cancer.

Cancer mortality in nonsmokers: prospective study by the American Cancer Society.

Standardized mortality ratios (SMR) were computed for nonsmokers who were compared with the total American Cancer Society study population for sites of cancer. The SMR were 64 for males and 96 for females for total cancer. Sites with low SMR in males (< 30) included lung, larynx, pleura, tongue, mouth, and pharynx. SMR less than 60 were observed for cancers of the esophagus and bladder. For female nonsmokers, relatively low SMR were observed for lung, larynx, and pharynx cancers. Death rates for cancers of all sites in females exceeded those in males in the age groups of 35--44, 45--54, and 55--64 years. Death rates were about the same in the 65- to 74-year-old group and about 40% higher in males than in females 75 years old and older. Lung cancer death rates in nonsmokers among both males and females were low and ranked between fourth and sixth in males and fifth to eleventh in females in the 5 age groups.

Smoking habits and tar levels in a new American Cancer Society prospective study of 1.2 million men and women.

In 1982 the American Cancer Society (ACS) enrolled over 1.2 million American men and women in a prospective mortality study of cancer and other causes in relation to environmental and life-style factors. Biennial follow-up is planned through 1988. At the time of enrollment, 23.6% of the men and 20.0% of the women were current smokers of cigarettes. Compared with a similar ACS study of 1 million subjects enrolled 23 years earlier, among men the proportion of current smokers was halved and that of ex-smokers doubled, while among women the proportion of ever-smokers increased by 10% and that of ex-smokers quadrupled. Most smokers of filter cigarettes had smoked nonfiltered cigarettes earlier in life. The median year for switching to filters was 1964, the year of the first Surgeon General's report. More than one-third of male smokers' and one-half of female smokers' current brands had tar yields below 12 mg; less than 9% of male smokers' and 4% of female smokers' current brands had tar yields of 20.2 mg or more (nonfilters). The study population differed in many respects from the general U.S. population; the study population had, for example, a much higher average educational level. Nevertheless, distributions of smoking habits changed a few percentage points after adjustment to the educational level of the general population.

Involuntary smoking and lung cancer: a case-control study.

In a case-control study in 4 hospitals from 1971 to 1981, 134 cases of lung cancer and 402 cases of colon-rectum cancer (the controls) were identified in nonsmoking women. All cases and controls were confirmed by histologic review of slides, and nonsmoking status and exposures were verified by interview. Odds ratios (OR) increased with increasing number of cigarettes smoked by the husband, particularly for cigarettes smoked at home. The OR for women whose husbands smoked 20 or more cigarettes at home was 2.11 (95% confidence limits: 1.13, 3.95). A logistic regression analysis showed a significant positive trend of increasing risk with increased exposure to the husband's smoking at home, controlled for age, hospital, socioeconomic class, and year of diagnosis. Comparison of women classified by number of hours exposed a day to smoke in the last 5 years and in the last 25 years showed no increase in risk of lung cancer.

Mortality among California Seventh-Day Adventists for selected cancer sites.

In previous reports concerning cancer among Seventh-Day Adventists (SDA), comparisons were made only with the general population. This report compared California SDA to a sample of non-SDA who were demographically similar to SDA. The study consisted of 17 years of follow-up (1960--76) on 22,940 white California SDA and 13 years of follow-up (1960--72) on 112,725 white California non-SDA. Both groups completed the same base-line questionnaire in 1960. Deaths were ascertained by annual contacts with each study member and by computer-assisted record linkage with the California State death certificate file. Results indicated that, with the exception of colon-rectal cancer and smoking-related cancers, the difference in risk of fatal cancer between SDA and non-SDA was substantially reduced when SDA were compared with a more socioeconomically similar population. The persistence of the low risk for colon-rectal cancer can probably be attributed to some aspect of the diet or life-style of the SDA.

Risk factors for fatal colon cancer in a large prospective study.

BACKGROUND: Diet, physical activity, obesity, aspirin use, and family history may all modify the risk of colon cancer, but few epidemiologic studies are large enough to examine these factors simultaneously. PURPOSE: We prospectively assessed the relationship of diet and other factors to risk of fatal colon cancer. METHODS: Using data from Cancer Prevention Study II--an ongoing prospective mortality study--we studied 764,343 adults who, in 1982, completed a questionnaire on diet and other risk factors and did not report cancer or other major illness. We assessed mortality through August 1988 and identified 1150 deaths from colon cancer (611 men and 539 women). Multivariate analyses were used to compare these case patients with 5746 matched control subjects drawn from the cohort. RESULTS: Risk of fatal colon cancer decreased with more frequent consumption of vegetables and high-fiber grains (P for trend = .031 in men and .0012 in women). The relative risk (RR) for the highest versus lowest quintile of vegetable intake was 0.76 in men (95% confidence interval [CI] = 0.57-1.02) and 0.62 in women (95% CI = 0.45-0.86). Dietary consumption of vegetables and grains and regular use of aspirin were the only factors having an independent and statistically significant association with fatal colon cancer. Participants who consumed the least vegetables and grains and no aspirin had a higher risk compared with those who consumed the most vegetables and used aspirin 16 or more times per month. For men in the former category, the RR was 2.4 (95% CI = 1.1-5.3); for women, it was 2.9 (95% CI = 1.3-6.7). Weaker associations were seen for physical inactivity, obesity, total dietary fat, and family history. No associations were seen with consumption of red meat or total or saturated fat in either sex, but this finding must be interpreted cautiously. CONCLUSIONS: These findings support recommendations that increased consumption of vegetables and grains may reduce the risk of fatal colon cancer. Regular use of low doses of aspirin may prove to be an important supplemental measure.

Smoking and lung cancer in women: findings in a prospective study.

Lung cancer rates in relation to smoking habits were studied in a cohort of 619,225 women traced over a 4-yr period (1982 to 1986). A total of 1,006 lung cancer deaths was recorded. The standardized mortality ratio (SMR) for women smokers was 12.7 for current smokers and 4.8 for exsmokers. For those women without a history of chronic diseases, the SMR rose to 17.6 for current smokers. The SMRs rose with the number of cigarettes smoked per day to 22.0 for women who smoked 31 or more per day. SMRs also increased with depth of inhalation; this increase was independent of the number smoked per day. SMRs also increased by duration of smoking and decreased with cessation of smoking. Mortality ratios for lung cancer in women ranged from about 2 to 1 to 3 to 1 in studies carried out in the 1950s and 1960s. As women have begun to smoke earlier in life, smoke more cigarettes a day, and inhale more deeply, we are now observing much higher SMRs in women with lung cancer, similar in magnitude to those seen in men in the earlier studies.

Short and long sleep and sleeping pills. Is increased mortality associated?

Prospective epidemiologic data of the American Cancer Society disclosed that reported usual sleep durations among groups who complained of insomnia and sleeping pill use "often" overlapped with those of groups who had no complaints. Reports of insomnia were not consistently associated with increased mortality when several factors were controlled; however, men who reported usually sleeping less than four hours were 2.80 times as likely to have died within six years as men who reported 7.0 to 7.9 hours of sleep. The ratio for women was 1.48. Men and women who reported sleeping ten hours or more had about 1.8 times the mortality of those who reported 7.0 to 7.9 hours of sleep. Those who reported using sleeping pills "often" had 1.5 times the mortality of those who "never" used sleeping pills. These results do not prove that mortality could be reduced by altering sleep durations or by reducing hypnotic prescribing. Rather, studies are needed to determine the causes of these mortality risk factors.

Mortality hazard associated with prescription hypnotics.

BACKGROUND: The American Cancer Society's Cancer Prevention Study II was a large survey designed primarily to examine cancer risks such as cigarette smoking. From the same survey and methods, data on usage of "prescription sleeping pills" in 1982 were examined. METHODS: Standardized mortality ratios were computed. Because sleeping pill use could be a proxy for other risk factors, cox proportional hazards models were computed to control for possible confounding factors as extensively as the data permitted. RESULTS: Men and women who reported taking prescription sleeping pills 30+ times in the past month had standardized mortality ratios of 3.18 and 2.82, respectively; controlling for 10-year age groups (p < 0.001). The standardized mortality ratios for usage 1-29 times/month were 1.8 and 1.48, respectively (p < 0.001). In proportional hazards models that controlled for 30 other risk factors and comorbidities simultaneously, the excess mortality risk associated with usage 30+ times per month remained significant, but hazard ratios were reduced to 1.35 for men and 1.22 for women. CONCLUSIONS: Use of hypnotics was associated with excess mortality. This methodology could not determine if hypnotic compounds caused the risks associated with their use, nor could the risks of individual compounds be determined. Since millions of Americans are currently taking hypnotics, long-term controlled trials are urgently needed to further guide both patients and physicians.

Nucleotide sequence analysis of an Entamoeba histolytica ferredoxin gene.

A cDNA clone (subclone B) previously isolated from the human parasite Entamoeba histolytica was characterized. DNA sequence analysis of subclone B identified the DNA as that encoding apoferredoxin. E. histolytica ferredoxin cDNA contains unusually short 5' and 3' noncoding regions of 9 and 25 nucleotides, respectively. A genomic ferredoxin clone was isolated from E. histolytica DNA, and comparison of genomic and cDNA sequences revealed that the ferredoxin gene is unspliced. The deduced amino acid sequence of E. histolytica ferredoxin resembles clostridial type of ferredoxins, and shows an arrangement of cysteines characteristic for the coordination of 2[4Fe-4S] centres. Of interest is the absence of an aromatic amino acid in the N-terminal region of the protein, a feature which is conserved in clostridial ferredoxins. Southern blot analysis of three different E. histolytica strains (200:NIH, Rahman and HM-1:IMSS) demonstrated the presence of a family of at least two ferredoxin genes. One of these genes is marked by restriction length polymorphisms in different strains of E. histolytica.

Entamoeba histolytica ribosomal RNA genes are carried on palindromic circular DNA molecules.

Highly abundant DNA fragments obtained after restriction enzyme digests of nuclear DNA of Entamoeba histolytica strain HM-1:IMSS have been cloned and characterized. Northern blot hybridization to E. histolytica rRNA and sequence analysis identified the abundant DNAs as ribosomal DNA containing species. Several overlapping clones containing these abundant DNAs were isolated from 4 different genomic libraries of E. histolytica. Alignment of the restriction maps was consistent with a circular molecule, about 24.6 kilobase pairs (kb) in size. Nuclease BA131 digestion provided additional evidence for the circular nature of this DNA. The ribosomal DNA molecule contains two large inverted repeat-regions, each at least 5.2 kb in length. Sequence analysis of clone R715 revealed homology to the large rRNA units of various eukaryotic organisms. This clone was located in both inverted repeats, suggesting two rRNA cistrons per molecule. The inverted repeats are flanked by stretches of DNA which contain tandemly reiterated sequences. Southern blot analysis of E. histolytica nuclear DNA revealed the presence of two populations of molecules. These molecules have identical arrangements of restriction sites, but differ in size (0.7 kb) in a fragment containing tandemly reiterated sequences. Analysis of E. histolytica nuclear DNA by electron microscopy also revealed circular molecules. These molecules are about 26.6 kb +/- 0.5 kb in size and contain structural features predicted by the restriction map of the extrachromosomal ribosomal DNA of E. histolytica.

Entamoeba histolytica: cloning and characterization of actin cDNA.

In order to study gene expression in the human parasite Entamoeba histolytica, a cDNA library of E. histolytica strain 200:NIH was constructed using the phage vector lambda gt10. Three cDNA clones (A, B and C) were selected for further analysis. Each of the three clones hybridized to a distinct mRNA. Two of these mRNAs were translated in vitro after hybrid selection, and yielded distinct translation products. One of these mRNAs, selected by hybridization to clone A, encodes the most abundantly expressed protein in E. histolytica. DNA sequence analysis of this cDNA clone identified the DNA as that encoding actin. The deduced amino acid sequence of E. histolytica actin resembles both cytoplasmic and muscle actins and has an unusual N-terminal glycine residue. We have shown that a family of actin genes is present in E. histolytica. Six different E. histolytica actin clones were obtained from a lambda gt10 genomic library using subcloned cDNA probes. Southern analysis of three different E. histolytica strains (200:NIH, Rhaman, and HM-1:IMSS) revealed at least four different actin genes. Strain HM-1:IMSS, however, differs by the presence of an additional actin gene.

Antithrombotic effect of a recombinant von Willebrand factor, VCL, on nitrogen laser-induced thrombus formation in guinea pig mesenteric arteries.

To assess the antithrombotic effectiveness of blocking the platelet glycoprotein (GP) Ib/IX receptor for von Willebrand factor (vWF), the antiaggregating and antithrombotic effects were studied in guinea pigs using a recombinant fragment of vWF, Leu 504-Lys 728 with a single intrachain disulfide bond linking residues Cys 509-Cys 695. The inhibitory effect of this peptide, named VCL, was tested in vitro on ristocetin- and botrocetin-induced platelet aggregation and compared to the ADP-induced platelet aggregation. In vivo, the antithrombotic effect of VCL was tested in a model of laser-injured mesentery small arteries and correlated to the ex vivo ristocetin-induced platelet aggregation. In this model of laser-induced thrombus formation, five mesenteric arteries were studied in each animal, and the number of recurrent thrombi during 15 min, the time to visualization and time to formation of first thrombus were recorded. In vitro, VCL totally abolished ristocetin- and botrocetin-induced platelet aggregation, but had no effect on ADP-induced platelet aggregation. Ex vivo, VCL (0.5 to 2 mg/kg) administered as a bolus i.v. injection inhibits risocetin-induced platelet aggregation with a duration of action exceeding 1 h. The maximum inhibition was observed 5 min after injection of VCL and was dose related. The same doses of VCL had no significant effect on platelet count and bleeding time.(ABSTRACT TRUNCATED AT 250 WORDS)

Contribution of passive smoking to respiratory cancer.

This article reviews data from experimental and epidemiologic studies on passive smoking and makes 12 recommendations for further study. The physicochemical nature of passive smoke, the smoke inhaled by nonsmokers, differs significantly from the mainstream smoke inhaled by the active smoker. At present, measurement of urinary cotinine appears to be the best method of assessing exposures to passive smoking. Data indicate that the greater number of lung cancers in nonsmoking women is probably related to environmental tobacco smoke. Exposures in utero and very early in life to passive smoking may be important in relationship to the subsequent development of cancer and need further consideration. The short-term effects of environmental tobacco smoke on the cardiovascular system, especially among high-risk individuals, may be of greater concern than that of cancer and requires further study. Further study of increased risks of lung cancers in relation to environmental tobacco smoke exposure requires larger collaborative studies to identify lung cancer cases among nonsmokers, better delineation of pathology, and more careful selection of controls. In addition, studies of epithelial cells or specific cytology should be undertaken to determine evidence of cellular changes in relation to environmental tobacco smoke exposure. Animal inhalation studies with passive smoke should be initiated with respect to transplacental carcinogenesis, the relationship of sidestream smoke exposure with lung cancer, the induction of tumors in the respiratory tract and other organs, and the differences in the physicochemical natures of sidestream and mainstream smoke.

Atherosclerosis and aneurysm of aorta in relation to smoking habits and age.

A direct relationship between the extent of atherosclerotic lesions and smoking habits and age was found in a study of 1,412 aortas collected at autopsy from male patients from 1965 to 1970. The extent of the lesions was recorded using grading systems for formation of plaques, ulceration, and calcification. These findings increased with the number of cigarettes smoked and were greater in ex-cigarette smokers and pipe or cigar smokers than in nonsmokers. More extensive alterations were found in the abdominal aorta than in the thoracic aorta. Aneurysms were found eight times more frequently among those smoking one to two packs of cigarettes per day than in nonsmokers. Black subjects showed about one-half the number of aneurysms and fewer extensive atherosclerotic lesions than white subjects. At ages over 65 years, abdominal aortic aneurysms were found in 11 percent of all men and in 16 percent of the heavy smokers.

Histologic type of lung cancer in relation to smoking habits, year of diagnosis and sites of metastases.

A study was made of histologic type of lung cancer in relation to smoking habit, year of diagnosis, age and sites of metastasis. It comprised 662 autopsies of men during the period from 1955 to 1972. As classified by the WHO system, 35.2 percent were epidermoid carcinoma, 24.6 percent were small cell carcinoma, 25.2 percent were adenocarcinoma and 14.2 percent were large cell undifferentiated carcinoma. The six non-smokers of the series were all found to be in class 3, adenocarcinoma. No clearcut and consistent relationships were observed. Although there was a steady decrease in the incidence of small cell carcinoma during this time period, this observation did not prove to be statistically significant. Small cell carcinomas increased with amount of smoking but not for all age groups. Adenocarcinomas decreased with advancing age but not in all smoking groups. Metastases were found in 96.3 percent of the cases and the sites most frequently involved were regional lymph nodes, liver, brain, distant lymph nodes, adrenals and bone. Small cell carcinomas showed the greatest percentage of involvement for those major sites and for the same sites, epidermoid carcinoma showed the lowest percentage.

Cigarette smoking and coronary artery disease. A macroscopic and microscopic study.

Vascular changes in the coronary arteries and intramyocardial arteries and arteriole were studied in 1,056 men in relation to the effects of cigarette smoking and to age. The analysis was based on both macroscopic and microscopic studies, and the pathologist was unaware of the identity of the cases. The macroscopic study found a greater association with atheroma than a previous study taken from autopsies. The microscopic study found moderate and advanced fibrous intimal thickening of the coronary arteries to be more frequent in smokers and related to the amount or degree of cigarette smoking. The increase in fibrous intimal thickening was greater for intramyocardial arteries than for subepicardial arteries. The most marked difference by smoking habits was found in the myocardial arterioles. Advanced hyaline thickening was found in 90.7 percent of those smoking two or more packs of cigarettes per day, in 48.4 percent of those smoking less than one pack per day, and not in any of those who never smoked regularly.

Presence of asbestos bodies in organs other than the lung.

This study was designed to test the hypothesis that subjects with many asbestos bodies in their lungs at autopsy would also have asbestos bodies in various other organs. The subjects included 19 cases with diagnosis of asbestosis at death (two of these had mesothelioma, five had lung cancer) and 18 with pleural plaques but not asbestosis. Occupational histories were obtained from relatives. In subjects occupationally exposed to asbestos, large numbers of asbestos bodies were found in the lungs, and in most of these, asbestos bodies were found in many of the other organs examined. In the 18 cases with only pleural plaques found at autopsy, considerably fewer asbestos bodies were found in the lungs. The number of other organs with one or more asbestos bodies ranged from 32 percent to 62 percent of the sites examined. The findings seem to confirm the hypothesis of the study.

Cigarette smoking and body weight in the Cancer Prevention Study I.

To investigate the generality of the association of heavy cigarette smoking with increased body weight, the relation of number of cigarettes smoked per day to relative body weight was examined in baseline data for 891,589 participants in a prospective study initiated in 1959. Although the relative weight of cigarette smokers was consistently lower than that of never and exsmokers, men and women smoking two or more packs of cigarettes per day were more likely to be categorized as moderately or severely overweight and less likely to be categorized as underweight than those smoking 10-20 cigarettes per day, despite somewhat greater educational attainment by heavier smokers. These analyses offer support for the temporal generality of the relation between heavier cigarette smoking and greater body weight, and suggest that this phenomenon cannot be explained by historic trends in the socioeconomic stratification of smoking prevalence or smoking dose.