Are the apparent effects of cigarette smoking on lung and bladder cancers due to uncontrolled confounding by occupational exposures?

It has been suggested that the well known associations between smoking and cancer may in part reflect inadequately controlled confounding due to occupational exposures. The purpose of the present analysis is to describe the association between cigarette smoking and both lung and bladder cancers, taking into account the potential confounding effects of over 300 covariates, most of which represent occupational exposures. A population-based case-control study was undertaken in Montreal to investigate the associations between a large variety of environmental and occupational exposures, on the one hand, and several types of cancer, on the other. Interviews were carried out with male incident cases of several sites of cancer, including 857 lung cancers and 484 bladder cancers. A group of non-smoking-related cancers, comprising 1,707 interviewed subjects, was used as one control group. Additionally, 533 population controls were interviewed and constituted a second control group. Interview information included detailed lifetime smoking histories, job histories, and other potential confounders. Each job history was reviewed by a team of experts who translated it into a history of occupational exposures. These occupational exposures, as well as nonoccupational covariates, were treated as potential confounders in the analysis of cigarette smoking effects. Regardless of whether population controls or cancer controls were used, the odds ratio (OR) between smoking and lung cancer (ranging from 12 to 16 for ever vs never smokers) was not materially affected by adjustment for occupational exposures. The odds ratios for bladder cancer (ranging from 2 to 3) were also unaffected by confounding due to occupational exposures.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of radioiodinated recombinant human TGF-beta 1 binding to bone matrix within rabbit skull defects

Bone healing is regulated in part by the local production of TGF-beta 1 and other growth factors produced by cells at the site of injury. The single application of recombinant human TGF-beta 1 (rhTGF-beta 1) to calvarial defects in rabbits induces an accelerated recruitment and proliferation of osteoblasts within 3 days. This ultimately results in the formation of new bone and the complete closure of the defect within 28 days. The persistence and localization of [125I]rhTGF-beta 1 within an osseous defect was investigated after applying a single dose of [125I]rhTGF-beta 1 formulated in a 3% methylcellulose vehicle. Normal bone encompassing the defect site, the periosteum, and the gel film covering the dura were harvested at 0, 4, 8, and 24 h and 3, 7, and 16 days after [125I]rhTGF-beta 1 application. The defect site-associated radioactivity was quantitated, visualized by autoradiography, and characterized by TCA precipitation and SDS-PAGE. Radioactivity was observed in autoradiographs of gross specimens, histologic sections of the bone matrix, and periosteal tissue surrounding the defect. There was a time-dependent decrease in TCA-precipitable radioactivity; however, radioactivity was still associated with the bone matrix 16 days after application of [125I]rhTGF-beta 1. SDS-PAGE and autoradiography of the radioactivity in homogenized bone and periosteal samples revealed a 25 kD band, suggesting that the radioactivity remaining at the defect site represented intact [125I]rhTGF-beta 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Linkage analysis of DRD2, a marker linked to the ataxia-telangiectasia gene, in 64 families with premenopausal bilateral breast cancer

Recent reports suggest that subjects who are heterozygous for the ataxia-telangiectasia gene are at increased risk of breast cancer. We conducted linkage analyses of 64 families with premenopausal bilateral breast cancer using DRD2, a marker linked to the ataxia-telangiectasia locus at 11q22-23. We assumed a model with dominant transmission of breast cancer. Lod scores summed over all families provided strong evidence against tight linkage (e.g., a lod score of -6.08 at theta = 0.00001), although a single family provides suggestive evidence of tight linkage to DRD2. Evidence against linkage to 11q was strongest among families that may involve the BRCA1 breast cancer susceptibility gene on 17q21. However, we did not observe evidence of linkage to 11q among the remaining subgroup with neither a family history of ovarian cancer nor the appearance of linkage to 17q21.

Stroke registers: a way to improve care

The authors describe their continued involvement in a research project to assess the incidence, case-fatality and management of stroke in three health authorities of Southern England. The article focuses on how the findings of their research have been used in two of the districts, and the role research can play in beginning to improve the services for people who have had strokes.

A linkage analysis of D17S74 (CMM86) in thirty-five families with premenopausal bilateral breast cancer

We report here results of a linkage analysis of a marker in 35 families in which the proband had premenopausal bilateral breast cancer. This group is of particular interest given their high family risk and the question of etiological heterogeneity. Probands were ascertained from cancer registries in Los Angeles County and Connecticut and major hospitals in Montréal and Québec. Assuming no residual heterogeneity and summing lod scores over all families, we obtained strong evidence against tight linkage (e.g., lod score at theta = 0.000001 is -3.39). To address the issue of heterogeneity, we performed admixture and predivided sample analyses. Using an admixture model we were able to reject the hypothesis of no linkage versus that of linkage with homogeneity (P = 0.045). However, we were unable to reject the hypothesis of no linkage versus linkage with heterogeneity (P = 0.119) or to distinguish between linkage with homogeneity and linkage with heterogeneity (P = 0.500). Predivided sample analyses based upon age of onset, pathological characteristics, time between diagnoses of the breast cancers in each bilateral proband, and the span of ages at diagnoses within a family did not discriminate between apparently linked and unlinked families.

A randomized trial to evaluate the risk of gastrointestinal disease due to consumption of drinking water meeting current microbiological standards

BACKGROUND

This project directly and empirically measured the level of gastrointestinal (GI) illness related to the consumption of tapwater prepared from sewage-contaminated surface waters and meeting current water quality criteria.

METHODS

A randomized intervention trial was carried out; 299 eligible households were supplied with domestic water filters (reverse-osmosis) that eliminate microbial and chemical contaminants from their water, and 307 households were left with their usual tapwater without a filter. The GI symptomatology was evaluated by means of a family health diary maintained prospectively by all study families over a 15-month period.

RESULTS

The estimated annual incidence of GI illness was 0.76 among tapwater drinkers compared with 0.50 among filtered water drinkers (p less than 0.01). These findings were consistently observed in all population subgroups.

CONCLUSION

It is estimated that 35% of the reported GI illnesses among the tapwater drinkers were water-related and preventable. Our results raise questions about the adequacy of current standards of drinking water quality to prevent water-borne endemic gastrointestinal illness.

Gastrointestinal health effects associated with the consumption of drinking water produced by point-of-use domestic reverse-osmosis filtration units

During a prospective epidemiological study of gastrointestinal health effects associated with the consumption of drinking water produced by reverse-osmosis domestic units, a correlation was demonstrated between the bacterial counts on R2A medium incubated at 35 degrees C and the reported gastrointestinal symptoms in families who used these units. A univariate correlation was found with bacterial counts on R2A medium at 20 degrees C but was confounded by the bacterial counts at 35 degrees C. Other variables, such as family size and amount of water consumed, were not independently explanatory of the rate of illness. These observations raise concerns for the possibility of increased disease associated with certain point-of-use treatment devices for domestic use when high levels of bacterial growth occur.

An intraoral splint for the prevention of microstomia from facial burns

Microstomia may be a disfiguring complication of severe burn injuries of the soft tissues of the face. The constriction of the perioral myocutaneous tissues following such trauma poses several problems and usually necessitates major plastic and reconstructive intervention. A novel technique is described which limited the anticipated constriction of perioral tissues in a 21-year-old female who suffered full skin thickness burns to 65 per cent of her body, including her face, following a self-induced petrol burn.

Cancer incidence and risk factors among Montreal residents of Italian origin

Cancer risks associated with Italian ethnicity were investigated using data from a large case-control study on the aetiology of several cancer sites in the male population of Montreal. Two approaches were taken. First, incidence rates were computed for Italians and for others in the Montreal area using our ascertained cases as numerators and census-derived denominators. Secondly, for respondents to the case-control study, an analysis was carried out with Italian ethnicity as the risk factor and a number of covariates as potential confounders. Out of 4553 incident cases in men aged 35-69, 301 were of Italian origin. As compared with other Montreal males, those of Italian origin had higher incidence rates for cancers of the stomach (p = 0.016, based on 31 cases) and of the colon and rectum (p = 0.102, based on 75 cases) and lower rates for cancer of the lung (p = 0.006) and prostate (p = 0.102, based on 24 cases). For other sites the differences between Montrealers of Italian and non-Italian origins were small. Montreal Italians manifested risks similar to those of the country of origin for cancer of the prostate and similar to the host country for cancers of the colon, rectum and liver. For other sites it was difficult to characterize the pattern because of wide variations among Italian registries. Over 80% of the study subjects in Montreal were interviewed and odds ratios (OR) for Italian ethnicity were estimated for each cancer site using all other sites as controls, adjusting for five potential confounders.(ABSTRACT TRUNCATED AT 250 WORDS)

The expression of IgG allotypes on platelets and immunization to IgG allotypes in multitransfused thrombocytopenic patients

We investigated whether the platelet-membrane surface carries IgG allotypic antigens and whether these determinants may be important in platelet transfusion therapy. Using a hemagglutination inhibition assay, we showed that the G1m IgG allotypes (a, x, f) and K1m and K3m light-chain allotypes are expressed on the surface of platelets, whereas G3m allotype antigenic determinants were not detectable. In 146 multitransfused thrombocytopenic patients, 35 (24%) patients were found to have antiallotypic antibodies. To study the effect of antiallotypic antibodies on platelet transfusion outcome, patients received platelet transfusions from donors, either positive or negative for the IgG allotype to which patients were immunized. Of the 19 antigen-positive and 19 antigen-negative platelet transfusions given, respectively, the mean platelet count increments at 1 hour were 8,402 +/- 6,402 +/- 6,721 (1 SD) and 9,799 +/- 5,559 (1 SD) P less than .2. Transfusion reactions were not more common when antigen-positive platelet transfusions were given. Despite the presence of IgG allotypic determinants on platelets, allotypic antibodies do not decrease platelet transfusion recovery. Furthermore, passive administration of plasma containing IgG allotypes to patients with antiallotypic antibodies does not lead to innocent bystander-mediated platelet destruction.

Interaction between norepinephrine and serotonin in the neuroendocrine control of growth hormone release in the rat

Both alpha 2-adrenergic (alpha 2) and serotonergic (5HT) neurons are associated with stimulation of GH secretion via GRH release. The object of this study was to determine whether the 5HT system is involved in the stimulation of GH secretion by alpha 2-receptor agonists. There are two parts of this study. In the first, the relationship between alpha 2-5HT systems were analyzed by determining if alpha 2-stimulated GH release is mediated by 5HT. In this model, systemically administered alpha 2-agonists [clonidine (CLON) or UK14,304] were tested against 5HT antagonists (meterogoline or cyproheptadine) or 5HT synthesis inhibitors (p-chlorophenylalanine methylester hydrochloride). In the second, sites of 5HT-GRH interaction were determined by testing the response to CLON after 5HT neurotoxin [5,7-dihydroxytryptamine (5,7-DHT)] microinjection at specific hypothalamic nuclei. In both experiments sequential blood samples were withdrawn from silastic jugular cannulas in unanesthetized, freely moving animals. Metergoline (0.045 and 0.135 mg/kg, iv) and cyproheptadine (0.969 micrograms/kg, iv) suppressed, in a dose-dependent manner, the CLON (33 or 66 micrograms/kg, iv)-induced GH surge that was detected 15-30 min after injection in control animals. Both cyproheptadine (0.969 micrograms/kg, iv) and p-chlorophenylalanine (300 mg/kg, ip) effectively suppressed the UK14,304 (220 micrograms/kg, iv)-induced GH surge that occurred 15-30 min after injection in control animals. These data suggest that an intact 5HT system is required for alpha 2-stimulated GH release. 5,7-DHT neurotoxin microinjected into the midline arcuate nucleus (6 micrograms/mg,iv) or bilaterally into the ventromedial nucleus or perifornical area (4 micrograms/0.2 microliter) 5 days previously suppressed the CLON (30 micrograms/kg)-induced GH surge only in animals with arcurate nucleus lesions. To determine if the suppression was mediated by inhibition of GH-releasing hormone (GRH) or stimulation of somatostatin (SRIF), an additional experiment was conducted including 5,7-DHT arcuate nucleus-lesioned animals injected with anti-SRIF. Inasmuch as anti-SRIF failed to reverse the 5,7-DHT suppression of GH secretion, the results of this experiment suggest that GRH mediates NE-5HT-induced GH secretion. In conclusion, these data suggest that alpha 2 activation of GH secretion requires intact serotonergic terminals in the arcuate nucleus and most likely involves GRH rather than SRIF, release.

Costs and statistical power associated with five methods of collecting occupation exposure information for population-based case-control studies

The ascertainment of information on past occupational exposure of study subjects is perhaps the main problem in case-control studies of occupational risk factors. Several methods have been proposed and used but little is known of their relative merits. The present study, undertaken in the context of a large ongoing case-control study of occupational cancer in Montreal, was designed to compare the costs of and statistical power to be derived from five plausible methods of data collection: 1) job titles abstracted from routine records, 2) job titles abstracted from routine records and processed through a job exposure matrix to derive exposure data, 3) job titles obtained by interview, 4) job titles obtained by interview and processed through a job exposure matrix to derive exposure data, and 5) job descriptions obtained by interview and processed by a team of experts to derive exposure data. Statistical power of the five methods was derived for 160 hypothetical risk factors, partly on the basis of empirical data from the data set and partly on the basis of some theoretical constructs. The design based on interview and expert evaluation was used as a reference, and the degree of misclassification of other methods was estimated in relation to this reference. For fixed sample size the interview and expert evaluation design was estimated to be much more costly than the others, but it provides much greater statistical power for detecting risks. Under the conditions of this investigation, this design was the most cost-effective. However, it is not clear to what extent this finding is generalizable.

Sexually dimorphic characteristics of clonidine-induced growth hormone release and autofeedback

The mechanism underlying the sexually dimorphic pattern of GH secretion in the rat has not been clearly elucidated. In this study differences in the regulation of GH secretion in males and females were analyzed by examining their sensitivity to alpha 2-adrenergic (alpha 2) stimulation and GH autofeedback. The model used in testing this system was the capacity of ovine (o) GH, injected into the third ventricle, to suppress the endogenous GH surge induced by clonidine (CLON), an alpha 2-agonist. In morning experiments, CLON (30 micrograms/kg BW, iv) was injected between 1000-1100 h in males. oGH (20 micrograms in 2 microliters vehicle) injected 3 h earlier inhibited the GH surge, which peaked 15 min after CLON injection in control animals receiving CLON alone. In females there was both no change in plasma GH levels and no difference between treatment groups in animals receiving 30, 50, 100, or 150 micrograms/kg CLON and saline controls. Preinjection of 20 micrograms oGH in proestrous or diestrous animals or 30 micrograms oGH in diestrous animals 3 h before CLON treatment did not depress plasma GH levels below those found in animals receiving CLON alone. Further, neither reducing the preinjection time to 2 h nor injecting 7, 13, or 20 micrograms oGH at this preinjection period suppressed basal or CLON-induced GH release. To facilitate comparisons in subsequent experiments the male protocol was followed. In evening experiments, CLON (injected between 2210-2240 h) stimulated a significant GH surge in diestrous females. However, preinjected oGH lowered basal GH levels but failed to suppress the CLON-induced GH surge. In somatostatin (SRIF) antiserum (anti-SRIF; 0.5 ml, iv)-treated adult diestrous animals, CLON induced a significant GH surge that was suppressed by oGH preinjection. In normal sheep serum-treated animals there was no significant response to either CLON alone or in combination with oGH. To determine the influence of ovarian hormones on GH release females were ovariectomized (OVXed) either pre- or postpubertally. After adult OVX, CLON induced an increase in GH release that was not suppressed by oGH pretreatment. In prepubertally OVXed animals CLON induced a substantial GH surge that was suppressed in animals preinjected with oGH. In prepubertally OVXed animals implanted with testosterone capsules the response to CLON and oGH was not significantly different from that after prepubertal OVX alone. Sham-operated animals responded to treatment in a manner similar to unoperated cycling females.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization of proteins secreted by sheep oviduct epithelial cells and their function in embryonic development

The role in early development of proteins secreted by oviduct epithelial cells has been investigated. Secreted proteins devoid of serum contamination have been produced by the surgical removal and immediate incubation of oviduct cells in [35S]methionine-containing medium. After electrophoretic separation, secreted polypeptides could be divided into those that were secreted uniformly throughout the oestrous cycle and a second class that showed a cyclical pattern of secretion. The first class of proteins represented a small proportion of total output whilst the predominant second class was composed mainly of polypeptides of Mr 92 and 46 × 10(3), respectively. Both of these polypeptide species, referred to as sheep oviduct proteins 92 and 46 (SOP 92, SOP 46), are detected only during the first 4 to 5 days after oestrus when the embryos are located in the oviduct. Oviduct cells collected at oestrus and maintained thereafter in culture secrete the same pattern of proteins and follow the same time course as their counterparts in vivo. The interaction between the oviduct proteins and the developing embryo was studied firstly by determining whether any of the secreted proteins bound to the zona pellucida. The results of iodination studies showed that two polypeptides of Mr 92 and 46 × 10(3), respectively, were bound to the zona pellucida of eggs removed from the oviduct but were absent from eggs that had not had contact with the oviduct epithelium. That these newly acquired proteins represent SOP 92 and 46 is suggested by their electrophoretic mobility and their ability to bind to the zona of follicular eggs when added in vitro and by the fact that they both disappear from the zonae of embryos after exit from the oviduct. The collection of unlabelled secreted proteins enabled us to produce a monoclonal antibody, which was used in the second series of experiments on oviduct-embryo interactions. The results confirmed that SOP 92 binds to the zona pellucida and moreover showed that this protein crosses the zona and becomes associated with the individual blastomeres of the developing embryo. These findings provide evidence that the mammalian oviduct probably plays a direct role in supporting embryonic development through specific polypeptides produced by its epithelium.

Cancer risks associated with 10 inorganic dusts: results from a case-control study in Montreal

A multicancer site, multifactor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with eligible cases, comprising all incident cases of 20 types of cancer who were male, aged 35-70 years, and a resident in Montreal. The interview was designed to obtain detailed lifetime job histories and information on potential confounders. Each job history was reviewed by a team of chemists and industrial hygienists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included; 3,726 cases were interviewed. For each site of cancer analyzed, controls were selected from among the other sites in the study. This report concerns the associations between the 12 main types of cancer in our series and 10 inorganic dusts that are found mainly in construction and metal industries. All site-exposure combinations were investigated. After intensive control for confounding, nonadenocarcinoma (NAC) of the lung was associated with long duration-high level exposure to silica (odds ratio [OR] = 1.4), excavation dust (OR = 1.9), concrete dust (OR = 2.5), abrasives dust (OR = 1.4), and alumina (OR = 1.5). It was difficult to disentangle the relative effects of those substances, and confounding among them was a distinct possibility. Although residual confounding by some uncontrolled factors may explain the elevated ORs, the results were compatible with the hypothesis of a nonspecific relation between NAC of the lung and respirable inorganic dusts as a class. Other associations that remained suggestive after in-depth analysis were silica and stomach cancer (OR = 1.2) and concrete dust and lymphoma (OR = 2.9).

Degree of confounding bias related to smoking, ethnic group, and socioeconomic status in estimates of the associations between occupation and cancer

In occupational cancer epidemiology, many studies are carried out without access to information on smoking and other potential confounding variables. It is unclear whether such deficiencies are likely to cause serious bias in estimates of cancer-occupation associations. An empiric investigation was carried out to determine the effect of inclusion or exclusion of three variables--smoking, ethnic group, and socioeconomic status--on estimates of odds ratios (OR) between 25 occupations and three types of cancer--lung, bladder, and stomach. Of the 75 associations studied, only one OR was distorted by more than 40% when comparing unadjusted with adjusted estimates; three were distorted by between 30% and 40%; four others by between 20% and 30%. Of the eight associations which were distorted by more than 20%, seven involved lung cancer and one involved bladder cancer; none involved stomach cancer. An additional analysis was carried out on the 25 lung cancer-occupation associations to determine whether the nature of the stratification on smoking (ie, whether crude or "precise" categories were used) gave different OR estimates. The differences in ORs induced by different parametrizations of the smoking variable were relatively small. Our results support the view that relative risks between lung cancer and occupation in excess of 1.4 are unlikely to be artifacts due to uncontrolled confounding. For bladder and stomach cancer, the corresponding cut point may be as low as 1.2. In studies of occupation and cancer, uncontrolled confounding due to smoking and social class may not be as serious a threat to the integrity of results as is sometimes feared.

Associations between several sites of cancer and ten types of exhaust and combustion products. Results from a case-referent study in Montreal

A population-based case-referent study provided information on the associations between several types of cancer and 10 types of exhaust and combustion products. All site-exposure combinations were investigated. An increased lung cancer risk, in particular squamous-cell cancers, due to exposure to gasoline and diesel exhausts was found. Among the associations that have not been subject to previous attention, the most promising leads for further investigation are the possible relations between gasoline and diesel exhaust and colorectal cancers, gasoline exhaust and kidney cancer, coal combustion products and pancreatic cancer (and possibly nonadenocarcinoma lung cancer), combustion products of heating oil and prostatic cancer, and natural-gas combustion products and bladder cancer.

Isolation and characterization of epididymal epithelial cell plasma membranes

Sperm maturation and storage occur in a unique milieu created in large part by the epididymal epithelium. To learn more about the interaction of the epididymal epithelial cell with both luminal and systemic environments, we now report on the preparation and characterization of epididymal epithelial cell plasma membranes. A preparation enriched for epididymal epithelial cell plasma membranes was isolated from collagenase-digested epididymal tubule fragments by hand-Dounce homogenization, differential centrifugation, and sucrose gradient centrifugation. The final membrane fraction was enriched 11-fold for the plasma membrane marker 5'-nucleotidase; 2.6-fold for the lysosomal marker acid phosphatase, and 3-fold for the Golgi marker thiamine pyrophosphatase. No enrichment was observed for mitochondrial or endoplasmic reticulum enzyme markers. Specific and saturable transferrin-binding activity was also detected in the final preparation. Electron microscopy revealed the presence of vesicles and sheets of membranes as well as an occasional Golgi apparatus. The plasma membrane fraction was used to generate monoclonal antibodies. Of 102 wells exhibiting growth, 12 were positive by immunofluorescent staining of frozen sections. Ten of these recognized determinants in epithelial cells, and 2 stained peritubular smooth muscle cells. Most of the epithelial cell-specific antibodies stained brush border alone or in combination with the basolateral plasma membrane. Three antibodies stained the Golgi apparatus. Most antibodies were specific for particular epididymal regions, 3 also recognized determinants in the kidney, and 1 stained residual bodies in the testis.

Smoking and degree of occupational exposure: are internal analyses in cohort studies likely to be confounded by smoking status?

Occupational cohort studies are usually carried out without the benefit of information on smoking habits of cohort members. One common approach to avoid confounding bias related to smoking habits is to carry out an internal analysis, comparing workers with different degrees of occupational exposure. The premise behind this approach is that within a cohort there is unlikely to be correlation between degree of exposure and smoking habits. If this were untrue, smoking could confound the disease-exposure relationships. Our purpose was to verify the premise. The study sample consisted of 857 French-Canadian men born between 1910 and 1930, with 11 or fewer years of education, and interviewed around 1980 in the context of an occupational cancer case-control study. For each man we had information on smoking habits, job history, and a history of the chemicals he was exposed to in each of his jobs. We computed two indices of the dirtiness of workers' job histories: one based on the job titles held by the man and a second based on the degree of exposures to workplace substances. There was no correlation between these indices of job dirtiness and smoking history. We also examined the smoking-exposure relationship among the subsets of men who had been occupationally exposed to ten especially noticeable substances. Within the subsets, there was no indication of a consistent difference among the smoking subgroups in level or duration of exposure to these index substances. These findings do not support the view that nonsmokers sought out cleaner job environments than smokers; they imply that internal analyses of "dose-response" in cohort studies are unlikely to be seriously confounded by smoking habits.

Discovering carcinogens in the occupational environment. Methods of data collection and analysis of a large case-referent monitoring system

A multi-cancer site, multi-factor, case-referent study was undertaken to generate hypotheses about possible occupational carcinogens. About 20 types of cancer were included. Incident cases among men aged 35-70 years and diagnosed in any of the major Montreal hospitals were eligible. Probing interviews were carried out for 3 726 eligible cases. The interview was designed to obtain detailed lifetime job histories and information on potential confounders. Each job history was reviewed by a team of chemists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included. For each site of cancer analyzed, referents were selected from among the other sites in the study. The analysis was carried out in stages. First a Mantel-Haenszel analysis was undertaken of all cancer-substance associations, stratifying on a limited number of covariates, and, then, for those associations which were noteworthy in the initial analysis, a logistic regression analysis was made taking into account all potential confounders. This report describes the fieldwork and analytical methods.

Associations between several sites of cancer and twelve petroleum-derived liquids. Results from a case-referent study in Montreal

A population-based case-referent study provided information on the associations between several types of cancer and 12 petroleum-derived liquids. All site-exposure combinations were investigated. The most interesting results concerned the following combinations: leaded gasoline-stomach cancer, aviation gasoline-kidney cancer (and the possible implications of this association for a similar effect of unleaded automotive gasoline), mineral spirits-squamous-cell cancer of the lung, diesel fuel-nonadenocarcinoma lung cancer, lubricating oils-squamous-cell lung cancer, cutting fluids-bladder cancer, other mineral oils-bladder cancer, mineral spirits-prostate cancer, diesel fuel-prostate cancer, and lubricating oils-prostate cancer.

Associations between several sites of cancer and nine organic dusts: results from an hypothesis-generating case-control study in Montreal, 1979-1983

A multi-cancer site, multi-factor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with over 2,000 subjects. All incident cases of 19 sites of cancer in males aged 35-70 and resident in Montreal were eligible. The interview was designed to obtain detailed lifetime job histories, and information on potential confounders. Each job history was reviewed by a team of chemists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included. For each site of cancer analyzed as a case series, controls were selected from among the other cancer sites in the study. This report concerns the associations between sites of cancer for which there were over 100 cases processed (stomach; colorectal, also analyzed by subsites; lung; prostate; bladder; kidney; non-Hodgkin's lymphoma) and nine organic dusts (wood; paper; grain; flour; fabrics; cotton; wool; synthetics; fur). All site-exposure combinations were investigated. The ones that provided the most interesting leads were lung-wood dust (odds ratio (OR) = 1.5), stomach-wood dust (OR = 1.5), colorectal-synthetic fiber (OR = 1.5), bladder-synthetic fiber (OR = 1.8), non-Hodgkin's lymphoma-cotton dust (OR = 1.9), colon-grain dust (OR = 2.6), prostate-grain dust (OR = 2.2), and prostate-paper dust (OR = 2.0). Only the associations with wood dust, synthetic fibers and cotton dust showed some evidence of "dose-response" with duration of exposure. Because it is such a common exposure and appears to increase lung and stomach cancer risks, wood dust may be responsible for a great deal of occupational cancer.

Incidence of hepatitis A virus (HAV) infection in rural Liberia

To provide background for future hepatitis A vaccine trials, sera were collected from 0- to 4-year-old Liberian infants and their mothers on two occasions an average of 14.75 months apart and tested for antibody to hepatitis A virus (anti-HAV). The prevalence of anti-HAV rose from 2.5% in infants 0-6 months of age to 70% in children 3-4 years of age and did not differ between male and female infants. The annual incidence of new infections was slightly lower in the first year of life (35%) than in the subsequent 3 years, when it averaged 45%. The presence of HBV infection did not affect the incidence of HAV seroconversion. No clinical hepatitis was recognized in the subjects who seroconverted. Dual hepatitis A and B virus infection were observed; these were all clinically inapparent. The extraordinary incidence of HAV infection documented in the present study offers an opportunity for vaccine efficacy trials requiring minimal numbers of subjects.

Further evidence of inactivity of hypothalamo-pituitary-thyroid axis in Snell dwarf mice

The effects of hemithyroidectomy (hemiTX) and complete thyroidectomy (TX) on the cellular composition and the mitotic activity of the anterior pituitary gland were examined in genetically thyrotropin (TSH)-deficient female Snell dwarf mice (dw/dw) and in phenotypically normal female mice (?/+) from the same strain. In normal (nondwarf) mice, both hemiTX and TX reduced the percentage of acidophilic (orange G-positive) cells and increased the percentage of thyrotropic (aldehyde fuchsin [AF]-positive) cells, whereas the percentage of gonadotrophs (PAS-positive cells) and chromophobes (unstained cells) was not affected. Both interventions increased the mean mitotic activity rate (MMAR) of the anterior pituitary lobe. This effect was related to the enhancement of the MMAR of acidophilic cells and, particularly, thyrotropic cells. The MMAR of thyrotrophs in thyroidectomized normal mice was significantly higher than that in sham-TX controls or in hemithyroidectomized animals. In Snell dwarf mice, neither hemiTX nor TX affected the percentage of the various cell categories (PAS-positive, unstained, and extremely rare AF-positive cells) in the anterior pituitary lobe. Furthermore, neither hemiTX nor TX substantially influenced the MMAR of the gland. No mitotic figures were found in the AF-positive cells. Since the AF-positive cells in the anterior pituitary of dwarf mice completely failed to respond to hemiTX or TX, we believe they are not true thyrotropic cells. Using electron microscopy, we confirmed a lack of somatotrophs, mammotrophs, and normal thyrotrophs in the anterior pituitary of Snell dwarf mice. The results provide morphological evidence of inactivity of the hypothalamo-pituitary-thyroid axis in Snell dwarf mice.

Quality of response in different population groups in mail and telephone surveys

Mail and telephone survey methods, with follow-up by other methods, can provide high response rates. However, it is not clear whether different population groups provide responses of different quality, thus creating risk of biased comparisons. A closely related problem is whether proxy response adequately substitutes for self-response. This study addressed these issues in the context of parallel mail and telephone health surveys carried out in Montreal. In the telephone survey, proxy respondents provided lower estimates of morbidity and health care utilization than self-respondents; in the mail survey, there was no difference between proxy and self-response. Response validity was assessed by comparing reported physician visits with those recorded by the government-run universal health insurance plan. In general, mail responses were more valid than telephone responses. In both methods, there were suggestive but not persuasive differences in validity among sociodemographic subgroups. In both methods, those reporting illness or medication use had less underreporting of physician visits than those not reporting such things.

Inactivation of hepatitis B and Hutchinson strain non-A, non-B hepatitis viruses by exposure to Tween 80 and ether

Titrated stocks of hepatitis B virus and Hutchinson strain non-A, non-B hepatitis virus were diluted in normal serum to contain, respectively, greater than or equal to 10(6) and greater than or equal to 10(4) chimpanzee infectious doses (CID50) per milliliter and exposed to 1% Tween 80 and 20% ether at 4 degrees C for 18 h. After evaporation of the ether, the treated sera were each inoculated into two chimpanzees. The animals remained free of serologic and biochemical evidence of hepatitis during a 6-month follow-up period, and were then shown to be susceptible to infection by challenge with the original untreated inocula. To assess the effect of exposure to Tween 80/ether on coagulation factors, four lots of antihemophilic factor (AHF) concentrate and 2 lots of commercial factor IX concentrate were treated as above. For the AHF concentrate there was an average of 70% recovery of factor VIII procoagulant activity, 93% recovery of factor VIII-related antigen, and 73% recovery of fibronectin opsonin activity and no detectable change in ristocetin cofactor activity or in fibronectin antigen. Crossed immunoelectrophoresis revealed no change in migration rate of fibrinogen, fibronectin, and von Willebrand factor (vWF), although the quantity of fibrinogen was reduced. Factor VIII procoagulant activity and vWF activity remained associated during chromatography on BioGel A15.

Blood-borne non-A, non-B hepatitis: lack of infectivity of feces from chimpanzees infected with a strain producing cytoplasmic tubular alterations

Fecal and serum samples from a chimpanzee with acute-phase, blood-borne non-A, non-B hepatitis were administered to four chimpanzees. Fecal material given either intravenously or orally did not result in abnormal levels of alanine aminotransferase or the occurrence of ultrastructural alterations in hepatocellular cytoplasm characteristic of non-A, non-B hepatitis during a one-year period of follow-up. Definite non-A, non-B hepatitis was later demonstrated in two of these animals four weeks after inoculation of acute-phase serum. Thus, feces do not appear to transmit this human strain of blood-borne non-A, non-B hepatitis.

Interference between non-A, non-B and hepatitis B virus infection in chimpanzees

Pre-existing chronic or concurrent acute non-A, non-B (NANB) virus infection has been found to interfere with hepatitis B virus (HBV) replication and to delay and moderate markedly the appearance of disease related to HBV infection in chimpanzees. The mechanism for this phenomenon remains unclear. These findings are of practical significance for vaccine safety testing and evaluation of methods for virus inactivation in chimpanzees. The possible occurrence of dual NANB and HBV infection requires that prolonged follow-up be carried out. Attempts to carry out inactivation studies on materials containing both types of virus may also provide misleading observations.

Preliminary report of an exposure-based, case-control monitoring system for discovering occupational carcinogens

There is no evidence concerning human carcinogenic potential of most substances to which workers are exposed. A case-control type method has been developed to discover heretofore unsuspected occupational carcinogens. Incident cases of cancer of several sites are ascertained and the subjects are interviewed to obtain detailed job histories. The job histories are subsequently examined by chemists and engineers who infer for each job a list of potential chemical and physical exposures. These lists of exposures then become the basis of case-control type statistical analyses, wherein each site included and each exposure noted in any history are evaluated for possible association. Controls can be selected in the general population, among non-cancer hospital patients or, as we do, among other cancer patients. Preliminary findings from a pilot study in Montreal show that 1) an efficient case ascertainment system and an acceptable interview procedure can be set up, 2) job histories provided by respondents are quite valid, 3) chemists' translations of job histories into histories of chemical exposures seem to be meaningful and useful, and 4) at least one carcinogenic agent, cigarette smoking, is detectable whether a population control series or a cancer control series is used.

A silver impregnation technique for the study of steroid receptors in central nervous system tissue prepared for autoradiography

The commonly used silver stains were found to be unsatisfactory for nervous tissue processed for autoradiography. A silver impregnation procedure for central nervous system tissues prepared for the autoradiographic study of steroid receptors is described. The procedure is a combination of several silver and reticular strains made up in solutions containing dimethylsulfoxide. The technique clearly distinguishes perikarya of neurons, brain nuclei and fiber tracts without substantial loss of silver grains, and thus greatly facilitates the identification of steroid receptor nuclei at all levels of the central nervous system.

Epidemiology of hepatitis B infection in Liberian infants

To provide background for a hepatitis B vaccine efficacy trial, sera were collected from 0- to 4-year-old Liberian infants and their mothers, on two occasions an average of 14.75 months apart, and tested for serological markers of hepatitis B virus infection. The prevalence of the hepatitis B surface antigen (HBsAg) was 2.9% in the 0- to 6-month age group and 23% in infants 3 to 4 years of age. HBsAg persisted for the 14.75-month average follow-up period in 80.8% of the infants tested. The annual incidence of development of HBsAg was 18.9% for infants less than 1 year of age and 13.6% in infants 3 to 4 years of age. Infants born to HBsAg carrier mothers had significantly higher age-specific prevalence and incidence of hepatitis B virus infection. However, it was estimated that only a minor proportion of hepatitis B infections in Liberia are derived by vertical transmission from carrier mothers.

Equality in medical care under national health insurance in Montreal

In November 1974, four years after national health insurance in Canada had eliminated all out-of-pocket payment for physicians' services, we surveyed 1559 households in a socially heterogeneous area of Montreal to assess social-class differences in the use of physicians' services. When reported health status as well as age and sex were taken into account, the rates of physician visits during the two-week period preceding the survey were essentially the same in the low, middle, and high economic classes, thus confirming that disparity of access had been reduced. However, relative to other groups, the poor still made considerable use of hospital clinics and emergency rooms for primary care and more of their visits entailed prescriptions and physician-initiated requests to return. The latter observations may indicate that the poor, as compared with other groups consulted the doctor for more advanced conditions. Official statistics showed no increase in the workload of the average physician, although the number of physician visits per person per year had risen steadily. There was no evidence of abuse of "free" medical care by the poor.

Staining calcified tissues in plastic embedding medium

Two procedures for staining sections of calcified teeth and/or bone embedded in plastic without dissolving the embedding medium were developed to study early bone regeneration in proximity to carbon implants in monkey alveolar bone and tissue degeneration in pathological human bone. These procedures allow differential staining of delicate bone tissues and prevent breakage of sections because the supporting plastic does not have to be removed.

A modified processing and sectioning technique for hard tissues

A new procedure for embedding and sectioning hard tissues was developed to study bone regeneration in relation to carbon implants used in crown and bridge preparations of maxillas and mandibles of nonhuman primates. Tissues were fixed in 10 percent neutral buffered formalin, dehydrated in 95 percent and 100 percent ethyl alcohol, and embedded in a modified Spurr's low-viscosity embedding medium. Tissues were sectioned as thin as 50 to 100 micron with a Buehler Isomet Model 11-1180 low speed saw. Unstained sections, as well as tissue stained with hematoxylin and eosin and Gomori's trichrome, were examined with a light microscope. The sections were of high quality without distortion. This new procedure expedited experimental work because decalcification of tissues was not needed and implants did not fragment.

Knife sharpening revolutionized

A new application has been found for an adhesive-backed, nylon polishing cloth previously used chiefly in the metallurgic field. When adhered to the glass plate of an automatic microtome knife sharpener, the cloth provides a superior sharpening surface and eliminates the need for resurfacing the plate. We have found this new technique simple, inexpensive, and timesaving.

Automated high-resolution gas chromatographic analysis of psychotropic drugs in biological fluids using open-tubular glass capillary columns. I. Determination of nomifensine in human plasma

An automated high-resolution gas chromatographic method has been developed for the determination of low levels of the antidepressant psychotropic drug Nomifensine in human plasma. The drug is extracted from alkalinized plasma with diethyl ether and then back-extracted into an acidic aqueous phase. After subsequent extraction into diethyl ether the drug is analysed by gas-liquid chromatography as its heptafluorobutyrate derivative using an OV-101 open-tubular glass capillary column with a nitrogen-specific detector. The propyl and butyl analogues of Nomifensine are used as internal standards, added to the plasma before extraction. The method is accurate, specific and precise, and capable of measuring plasma concentrations down to a level of 2 ng/ml. A preliminary study of the pharmacokinetics of the drug, together with steady-state level measurements in normal individuals receiving therapeutic dosages of Nomifensine, has been made.

Mutual visual regard during mother-infant play

Mutual visual regard was observed in 48 mother-infant dyads during a 6-min. play session. Infant-mother dyads containing 4 mo. -olds displayed significantly more mutual visual regard than dyads containing 6- or 8-mo.-olds. In addition, the more time infants spent in face-to-face interaction with mother, the more smiling they engaged in. No sex difference were observed.