Oral contraceptive use and risk of cutaneous malignant melanoma

The relation between cutaneous malignant melanoma (MM) and the use of oral contraceptives (OC) was investigated in a case-control study carried out from 1979 to 1991 among patients in hospitals and clinics in the Philadelphia (PA) and New York City (NY) metropolitan areas (United States). Cases were 615 women under age 70 who recently had been diagnosed with invasive melanoma; controls were 2,107 women of the same ages who had been treated for other conditions unrelated either to OC use or to skin diseases. The cases were categorized as severe or nonsevere based on the depth of invasion of the tumor or the presence or absence of metastases. Among the severe cases, OC use was not associated with MM: the relative risk (RR) estimate for ever-use was 1.1 (95 percent confidence interval [CI] = 0.8-1.5) and the estimate for 10 or more years of use was 1.1 (CI = 0.6-2.1). Nor was risk associated with recent use, long latency, or young age at first use. Among the nonsevere cases, ever-use of oral contraceptives was associated positively with MM (RR = 1.5, CI = 1.1-2.4) but there was no trend with increased duration of use. The findings provide evidence against the hypothesis that OC use increases the risk of malignant melanoma. The elevated estimates among the nonsevere cases most likely reflect selection bias rather than a causal relation.

Regulation of cell substrate adhesion: effects of small galactosaminoglycan-containing proteoglycans

Cell adhesion is a process which is initiated by the attachment of cells to specific sites in adhesive matrix proteins via cell surface receptors of the integrin family. This is followed by a reorganization of cytoskeletal elements which results in cell spreading and the formation of focal adhesion plaques. We have examined the effects of a class of small galactosaminoglycan-containing proteoglycans on the various stages of cell adhesion to fibronectin-coated substrates. Our results indicate that dermatan sulfate proteoglycans (DSPGs) derived from cartilage, as well as other related small proteoglycans, inhibit the initial attachment of CHO cells and rat embryo fibroblasts to substrates composed of the 105-kD cell-binding fibronectin fragment, but do not affect cell attachment to intact fibronectin. Although this effect involves binding of DSPGs to the substrate via the protein core, the intact proteoglycan is necessary for the observed activity. Isolated core proteins are inactive. The structural composition of the galactosaminoglycan chain does not appear to be functionally significant since both chondroitin sulfate and various dermatan sulfate proteoglycans of this family inhibit cell attachment to the fibronectin fragment. Neither the percentage of cells spread nor the mean area of spread cells adhering to substrates of intact fibronectin was significantly affected by the DSPGs. However, significantly fewer cells formed focal adhesions in the presence of DSPGs as compared with untreated control cells. These results suggest that the binding of small galactosaminoglycan-containing proteoglycans to a fibronectin substrate may affect several stages in the cell adhesion process.

Reproductive factors and risk of myocardial infarction

The relation of reproductive factors to risk of myocardial infarction in women aged 45-69 years was examined in a case-control interview study carried out in Massachusetts from 1986 to 1990. Each of 858 cases of first myocardial infarction was age-matched with a control from the same precinct of residence. Conditional logistic regression was used to control the matching factors and the major known and suspected risk factors for coronary heart disease. For parous women compared with nulliparous women, the estimated relative risk of myocardial infarction was 1.8 (95% confidence interval (CI) 1.0-3.3). Among parous women, the relative risk estimate for five or more births relative to fewer births was 1.4 (95% CI 1.0-2.0); the estimate for a first birth before age 20 relative to a later age at first birth was 1.7 (95% CI 1.1-2.6). The greatest increase in risk was observed for women who had both an early age at first birth and five or more children. However, confounding by factors related to socioeconomic status may have contributed to the results. Compared with women who had a natural menopause at age 50 or older, women who reached the menopause before age 45 were at increased risk regardless of type of menopause: The estimated relative risks were 2.1 (95% CI 1.3-3.2), 1.7 (95% CI 1.0-2.7), and 1.7 (95% CI 1.0-2.8) for early natural menopause, bilateral oophorectomy, and hysterectomy with retention of one or both ovaries, respectively. These results suggest that early cessation of ovulatory function, whether due to natural causes or to surgery, increases the risk of myocardial infarction. Age at menarche was not related to myocardial infarction risk.

Chemical burns: our 10-year experience

A review of 173 patients with chemical burns admitted to our burn unit was carried out during the years 1976-85. Most burns were work related (83 per cent). The majority of patients were men aged 21-50 years (mean age = 29.6 years). The mean total body surface area involved was 3.6 per cent (range = 1-30 per cent). The mean length of stay in hospital was 6.3 days (range = 1-52 days). The extremities were involved in 68 per cent of the patients. The more common aetiological agents were bromine and its compounds (36 per cent), then acids (21 per cent), alkalis and organic substances (14.5 per cent each). The severest burns were caused by the inorganic substances. Delayed admission was most characteristic of the bromine and alkali burns. Complications included local infection (19 cases), systemic infection (two cases), inhalation injury (two cases), tissue necrosis (one case) and corneal erosion (one case). There were no deaths. Increased awareness of the hazardous potential of chemicals should help reduce the incidence of chemical burns.

The predominant form of secreted colony stimulating factor-1 is a proteoglycan

Colony stimulating factor-1 (CSF-1) is a homodimeric glycoprotein that humorally regulates the proliferation and differentiation of mononuclear phagocytic cells and locally regulates cells of the female reproductive tract. Alternative splicing of the human CSF-1 mRNA leads to alternative expression of the CSF-1 homodimer as a secreted glycoprotein or as a membrane-spanning molecule with cell surface biological activity. In the present study, analysis of immunoaffinity-purified CSF-1 from mouse L929 cell medium by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that CSF-1 is predominantly secreted as highly sulfated species of 375- and 250-kDa with a smaller amount of a 100-kDa species. Analysis by gel filtration in 4 M guanidine HCI buffer, indicated that, in contrast to the 100-kDa species, the highly sulfated species exhibit anomalously high molecular weights and self-association on SDS-PAGE similar to the dermatan sulfate proteoglycan, biglycan. The three predominant CSF-1 species were shown to be an 80-kDa homodimer, an 80-kDa/50-kDa heterodimer, and a 50-kDa homodimer. The 80-kDa subunit contained a single 18-kDa chondroitin sulfate chain that was absent from the 50-kDa subunit. Furthermore, treatment of the 80- and 50-kDa subunits, synthesized in the presence of tunicamycin, with chondroitinase ABC, neuraminidase, and endo-alpha-N-acetyl galactosaminidase reduced their apparent molecular masses to 60 and 25 kDa, respectively. These results are consistent with intracellular proteolytic cleavage of the 80-kDa chondroitin sulfate containing subunits from the membrane spanning CSF-1 precursor at a point carboxyl-terminal to the single consensus sequence for glycosaminoglycan addition and cleavage of the 50-kDa glycoprotein subunit at a position aminoterminal to this site. The predominance of the proteoglycan form of secreted CSF-1, which represents only 3-4% of the total trichloroacetic acid-precipitable counts released from 35SO4(2-)-labeled L cells, has important implications for regulation by this growth factor.

Expression of growth factors in a pancreatic islet regeneration model

In this model of pancreatic regeneration, the initial trophic effect of cellophane wrapping is upon the ductular-epithelium, as shown by autoradiographic analysis following a single pulse of 3H-TdR. The uptake of 3H-TdR by ductular cells is maximal approximately 4 weeks before the peak uptake of the label by islet cells. Six weeks after the pulse, most of the label is contained in differentiating islet cells, not ductular cells. This phenomenon suggests that wrapping of the pancreas induces "progenitor" cells to differentiate along the line of endocrine cells. The essentially negative observations on REG gene expression in the regenerating hamster pancreas indicate that the message for this gene is either not involved in the regeneration process or that it is sufficiently different from the rat gene (a rat control probe was used) that it precludes detection by our methodology. It might be necessary therefore, to generate a hamster REG specific probe in order to further study this issue. In conclusion, the established model of cellophane wrapping of the pancreas provides a useful tool whereby the induced growth of beta-cells can be observed. The sequence appears to be initial stimulation of ductal cells followed by islet differentiation. Of the candidate genes, it appears that reg does not participate in the process. We will however, examine other candidate genes to elucidate the mechanism whereby celophane wrapping induces growth of beta-cells.

Factors controlling pancreatic islet neogenesis

We have established a model in which cellophane wrapping induces reiteration of the normal ontogeny of beta-cell differentiation from ductal tissue. The secretion of insulin is physiologic and coordinated to the needs of the animal. Streptozotocin-induced diabetes in hamsters can be "cured" at least half the time. There appears to be activation of growth factor(s) within the pancreas, acting in an autocrine, paracrine, or juxtacrine manner to induce ductal cell proliferation and differentiation into functioning beta cells. Given the results of our studies to date, it does not seem premature to envisage new approaches to the treatment of diabetes mellitus. Identification of the factor(s) regulating islet-cell proliferation and differentiation in our model may permit islets to be grown in culture. This concept could be extended to induce endocrine cell differentiation in vitro as well. Furthermore, islet-cell growth factors could be used to provide "trophic support" to islet transplants as a means of maintaining graft viability. There may also be greater scope for gene therapy when the growth factor(s) have been isolated, purified, sequenced, and cloned.

Trophic stimulation of the ductular-islet cell axis: a new approach to the treatment of diabetes

We have established a model in which cellophane wrapping induces reiteration of the normal ontogeny of beta-cell differentiation from ductal tissue. The secretion of insulin is physiologic and coordinated to the needs of the animal. Streptozotocin-induced diabetes in hamsters can be "cured" at least 1/2 the time. There appears to be activation of growth factor(s) within the pancreas acting in an autocrine, paracrine or juxtacrine manner to induce ductal cell proliferation and differentiation into functioning beta-cells. Given the results of our studies to date, it does not seem premature to envisage new approaches to the treatment of diabetes mellitus. Identification of the factor(s) which regulate islet cell proliferation and differentiation in our model may permit islets to be grown in culture. This concept could be extended to induce endocrine cell differentiation in-vitro as well. Furthermore, islet cell growth factors could be used to provide "trophic support" to islet transplants as a means of maintaining graft viability. There may also be greater scope for gene therapy when the growth factor(s) has been isolated, purified, sequenced and cloned.

The partial isolation and characterization of ilotropin, a novel islet-specific growth factor

In this series of studies, we have presented evidence for a novel, pancreatic islet-specific growth factor, which we call ilotropin. Ilotropin is acid stable, heat stable, ethanol-precipitable, and sensitive to trypsin digestion. It appears to have a molecular weight between 29 - 44,000, and preliminary data not presented here suggests that it has a relatively basic pI. Unlike many other growth factors, ilotropin does not bind to heparin. Ilotropin is distinguishable from most of the known growth factors on the basis of at least one of the characteristics established in these studies. The apparent molecular weight of 29 - 44,000 eliminates all but the larger growth factors such as PDGF and hepatic growth factor. The fact that ilotropin is acid stable rules out identity with hepatic growth factor, and its lack of binding to heparin and apparent basic pI rules out identity with PDGF. Thus, the combination of characteristics described in these studies eliminates most of the known growth factors as candidates for the role of ilotropin. Certain growth factor precursor molecules (e.g. TGF-a) and several interleukins and cytokines (e.g. pro-IL-1 and melanocyte growth factor) also fall into this molecular weight range. Whether these proteins might be related to ilotropin or play a role in its biological activity remains to be determined. Current studies of ilotropin include further purification to homogeneity, determination of the peptide sequence of ilotropin, and development of an in vitro bioassay using trophic responses of primary cultures of pancreatic duct cells as an indicator of ilotropin activity. With purified material we ought to be able to identify the cells of origin and the target cells for the action of ilotropin, and establish assays to determine the relationship to failure of beta-cell regeneration that accompanies diabetes. Ultimately we hope that ilotropin may lead to new ways of approaching aspects of the problems presented in pancreatic beta-cell failure.

Breast cancer risk after estrogen replacement therapy: results from the Toronto Breast Cancer Study

The authors examined noncontraceptive estrogen use in relation to breast cancer risk in women under age 70 in a case-control study conducted in Toronto, Canada. Cases were 607 women with incident primary breast cancer, identified at the time of hospitalization for treatment. They were compared to 1,214 controls matched to the cases on neighborhood and decade of age. Information was obtained through personal interviews conducted in the subjects' homes. Most estrogen users had taken conjugated estrogens, and only 7% had also taken progestogens. Compared with never use, the estimated relative risk for ever use of unopposed conjugated estrogens was 0.9 (95% confidence interval (Cl) 0.6-1.2) after allowance for multiple confounding factors. Relative risk estimates for most duration categories were close to 1.0; the estimate for the longest duration category, greater than or equal to 15 years of use, was elevated (1.5, 95% Cl 0.6-3.8), but there was not a significant trend with increasing duration. The estimate for current use or use that ended less than 12 months before interview and had lasted for at least 5 years was 0.9 (95% Cl 0.4-1.9). The results provide evidence against an increase in risk among women who used unopposed conjugated estrogens for less than 15 years and for recent users; for women with durations of at least 15 years, an increase could not be ruled out.

Estrogen replacement therapy and the risk of breast cancer: results from the case-control surveillance study

To examine the relation of noncontraceptive estrogen use to the risk of breast cancer among postmenopausal women, the authors conducted a case-control study: 1,686 cases were compared with 2,077 hospital control subjects, of whom 1,120 had non-gynecologic cancers and 957 had nonmalignant (also non-gynecologic) conditions. Data were obtained from 1980 to 1986, by interview of subjects in hospitals in the United States and Canada. The relative risk estimate for any use of replacement estrogens unopposed by progestogens was 1.2 (95% confidence interval (Cl) 1.0-1.4), after adjustment for age and type of menopause; when all known risk factors for breast cancer were taken into account in a multivariate analysis, the estimate was similar. For use of at least 15 years duration, the estimate was 0.9 (95% Cl 0.5-1.9). Most of the unopposed use was of conjugated estrogens: overall, the relative risk (95% Cl) was 1.3 (1.0-1.6); for durations of 15 or more years, it was 0.9 (0.4-1.9); for use of 5 years followed by a latent interval of 15 or more years, it was 1.3 (0.7-2.4); and for current use it was 1.1 (0.7-1.6). There was no evidence of increased breast cancer risk when the conjugated estrogen users were divided according to dose. There was little use of estrogens opposed by progestogens; the relative risk estimate was 1.7 (95% Cl 0.9-3.3). The results of this large study provide no evidence that the use of unopposed conjugated estrogens increases the risk of breast cancer, even after long durations of use or long latent intervals, but the possibility of a modest increase (less than a doubling) could not be excluded. There were insufficient data to evaluate the effects of nonconjugated estrogens and of combined estrogen and progestogen therapy.

Steroid receptor status and the epidemiology of breast cancer

This case-control study examined risk factors for breast cancer according to tumor estrogen receptor (ER) status and progesterone receptor (PR) status. The data included 607 case patients and 1214 control subjects matched by age and residence. Of 528 case patients with steroid receptor information, 67% had ER-positive tumors and 55% had PR-positive tumors. Odds ratios for ER-positive and ER-negative breast cancer were similar with respect to menopausal status, age at menarche, history of cystic breast disease, and Quetelet Index. Family history of breast cancer was a stronger risk factor for ER-negative than for ER-positive breast cancer and the odds ratios for number of births were suggestive of a different effect. While ER and PR status were highly correlated, there were some differences in their associations with risk factors. Odds ratios for PR-positive and PR-negative breast cancer differed for number of births and were suggestive of differences with respect to menopausal status, Quetelet Index, and family history of breast cancer. These findings do not suggest different causal pathways for ER-positive and ER-negative breast cancer. However, they do indicate that PR status may play a role in the etiology of breast cancer.

An analysis of mortality in patients with burns covering 40 per cent BSA or more: a retrospective review covering 24 years (1964-88)

The charts of patients with burns covering more than 40 per cent of the body surface area (BSA) who were admitted to the Burn Unit of the Soroka Medical Center, Beersheva, Israel, between the years 1964 and 1988 were reviewed for mortality rate and causes of deaths. The factors affecting survival are reviewed and analysed.

Maternal alcohol use in relation to selected birth defects

The hypothesis that maternal alcohol consumption affects the development of structures possibly derived from a common embryonic cell population, the cranial neural crest, was explored using data collected by a case-control surveillance program of birth defects in greater Boston, Philadelphia, and Toronto, Ontario, Canada, and in five counties in Iowa from 1983 through 1987. Maximum and average alcohol consumption during the first four lunar months of pregnancy were compared between the mothers of 1,464 infants with malformations of the ear, face, anterior neck, and upper heart (cranial neural crest cases) and 1,427 infants with other malformations (controls). For maximum number of drinks in a day and average number of drinking days per week, relative risks approximated unity across levels of exposure. For average number of drinks per drinking day, the relative risk (and 95% confidence interval) for heavy intake (5 or more drinks) was 1.8 (0.8-4.4). When the largest defect subgroup of cases, infants with cleft lip with or without cleft palate, was considered separately, the relative risk for an average of 5 or more drinks per drinking day was 3.0 (1.1-8.5). These findings suggest that maternal alcohol use is less related to overall malformations derived from cranial neural crest cell than to one specific defect among them--cleft lip with or without cleft palate. However, the latter association has not been reported previously in humans and remains to be confirmed in other studies.

Breast cancer and cigarette smoking: a hypothesis

In many studies, cigarette smoking has been associated with a small increase in breast cancer risk. The authors evaluated the relation of smoking to breast cancer risk in two case-control studies carried out from 1982 through 1986. In Canada, 607 women with breast cancer and 1,214 controls matched on decade of age and neighborhood were interviewed at home. In the United States, 1,955 cases of breast cancer and 805 controls with other cancers were interviewed in the hospital. In both studies, breast cancer risk was associated weakly with cigarette smoking overall. The odds ratio for women who had smoked 25 or more cigarettes per day as compared with never smokers was 1.2 (95% confidence interval (CI) 0.9-1.6) in the Canadian study and 1.2 (95% Cl 0.9-1.6) in the US study. In both studies, breast cancer risk was more strongly related to commencement of smoking at a young age. Among women who smoked at least 25 cigarettes per day in the most recent year of smoking, the odds ratios for commencement before age 16 years were 1.7 (95% Cl 1.0-2.9) in the Canadian data and 1.8 (95% Cl 1.0-3.4) in the US data, and the odds ratios for commencement at even younger ages were higher. The associations were not explained by duration of smoking, by the time elapsed since commencement, or by factors associated with cigarette smoking such as alcohol consumption or oral contraceptive use. Our findings raise the hypothesis that exposure to cigarette smoke during adolescence may increase a woman's risk of breast cancer. The hypothesis has biologic plausibility: cigarette smoke contains known carcinogens, and the developing breast is especially susceptible to cancer initiation.

The risk of liver neoplasia in relation to combined oral contraceptive use

Benign liver tumors occurring in young women were rarely reported in the medical literature before the introduction of oral contraceptives in the early 1960s. Subsequently, there were numerous case reports from the U.S. and other countries of liver tumors in women who used combined oral contraceptives. These reports, coupled with data from two U.S. case-control studies, indicate that the risk of hepatocellular adenoma increases sharply with increasing duration of oral contraceptive use. Case reports suggest that there may be a similar effect on the risk of focal nodular hyperplasia, but this is not established because there have been no case-control studies of the lesion. The incidence of benign liver disease attributable to oral contraceptive use in the U.S. is small because of the very low incidence of the disease. There have also been numerous case reports of malignant liver tumors in young women who used oral contraceptives. Seven case-control studies have been conducted--two in Great Britain, two in the U.S., one in Italy, one in several developing countries (conducted by the World Health Organization (WHO)), and one in South Africa. Data from the first five studies, all conducted in low risk populations, indicated an association of hepatocellular carcinoma (largely in the absence of liver cirrhosis) with oral contraceptive use. Because of small numbers estimates were unstable, but the risk did not appear to be increased appreciably for durations of use less than about five years. For longer durations, the risk appeared increased by five- to tenfold or more. There was little evidence of hepatitis B infection in the cases, but systematic determinations were not carried out. An increased risk of cholangiocarcinoma was not established, but few of these lesions were studied. Because the incidence of primary liver cancer in Northern Europe and the U.S. is low, the incidence attributable to oral contraceptive use is also likely to be low. The WHO study was carried out in eight countries, most of which have a high incidence of liver cancer and a high prevalence of a predisposing factor, hepatitis B infection. Similarly, the South African study was carried out among black women, and virtually all of the cases had serological evidence of hepatitis B infection. Both studies indicated no association of short-term oral contraceptive use with risk of hepatocellular carcinoma, and the WHO study indicated a lack of association with cholangiocarcinoma.