Alcohol consumption and non-Hodgkin lymphoma in a cohort of older women

We investigated the relation of alcohol consumption to risk of non-Hodgkin's lymphoma (NHL) in a cohort of 35 156 Iowa women aged 55-69 years who participated in the Iowa Women's Health Study in 1986. Alcohol consumption at baseline was obtained using a mailed questionnaire. During the 9-year follow-up period, 143 incident cases of NHL were identified. Higher alcohol consumption was significantly associated with a decreased risk of NHL (P-trend = 0.03). Compared to non-drinkers, multivariate-adjusted relative risks (RRs) were decreased for women with intake of < or = 3.4 g day(-1) (RR = 0.78; 95% confidence interval (CI) 0.51-1.21) and > 3.4 g day(-1) (RR = 0.59; 0.36-0.97). The inverse association could not be attributed to one particular type of alcoholic beverage, although red wine (RR = 0.21 for > 2 glasses per month vs non-drinker; 0.05-0.86; P-trend = 0.02) has the most distinct effect. The apparent protective effect was universal regardless of specific NHL grade or Working Formulation subtype, but was most pronounced for nodal NHL (RR = 0.48; 0.26-0.90; P-trend = 0.01) and low-grade NHL (RR = 0.52; 0.21-1.26; P-trend = 0.05). These data suggest that moderate alcohol consumption is inversely associated with the risk of NHL in older women and the amount of alcohol consumed, rather than the type of alcoholic beverages, appears to be the main effect determinant.

Hormone replacement therapy and risk of breast cancer with a favorable histology: results of the Iowa Women's Health Study

CONTEXT

Long-term, postmenopausal use of hormone replacement therapy (HRT) appears to increase breast cancer risk. Whether the effect of HRT use on risk of breast cancer varies among histological types of invasive carcinoma is unknown.

OBJECTIVE

To determine associations between HRT use and risk of ductal carcinoma in situ (DCIS), invasive carcinoma with favorable histology, and invasive ductal or lobular carcinoma.

DESIGN

Prospective cohort study whose participants were followed up continuously for 11 years from January 1986 to December 1996.

SETTING AND PARTICIPANTS

Iowa Women's Health Study, a population-based random sample of postmenopausal women aged 55 to 69 years in 1986. A total of 1520 incident breast cancer cases occurred in the at-risk cohort of 37 105 women.

MAIN OUTCOME MEASURES

Multivariate-adjusted relative risk (RR) of tumor-specific breast cancers associated with duration of ever, current, or past HRT use.

RESULTS

Duration of ever HRT use was associated with risk of invasive carcinoma with a favorable histology, with an RR of 1.81 (95% confidence interval [CI], 1.07-3.07) for those who used HRT 5 or fewer years vs an RR of 2.65 (95% CI, 1.34-5.23) for those who used HRT for more than 5 years (P for trend = .005) after adjustment for age and other breast cancer risk factors. There was no association between ever HRT use and the incidence of DCIS or invasive ductal or lobular carcinoma. Among current hormone users, after adjusting for age and other breast cancer risk factors, the RRs (95% CIs) of invasive carcinoma with a favorable histology were 4.42 (2.00-9.76) and 2.63 (1.18-5.89) for 5 or fewer years of use and for more than 5 years of use, respectively. Risk of invasive ductal or lobular carcinoma was associated with current use (< or =5 years) of HRT with an RR of 1.38 (95% CI, 1.03-1.85).

CONCLUSIONS

Exposure to HRT was associated most strongly with an increased risk of invasive breast cancer with a favorable prognosis. These data add important clinical information for assessing the risks and benefits of HRT use.

Surrogate end-point biomarkers as measures of colon cancer risk and their use in cancer chemoprevention trials

Surrogate end-point biomarkers (SEBs) have become widely used in short-term cancer chemoprevention trials in place of cancer end points. This paper discusses criteria relevant to the selection and validation of SEBs for colon cancer risk and the use of SEBs in colon cancer chemoprevention trials. As with a number of other cancers, colon carcinogenesis is the result of a multistep process in which an increasing number of alterations, including specific gene mutations, occur as cells progress from normal to precancerous states of increasing size and dysplasia to cancer and finally to metastatic disease. Ideally, a SEB would show differential expression between the various phases of colon carcinogenesis (i.e., normal, premalignant, and malignant tissues) and be associated with risk of colon cancer. Some SEBs that do not meet these criteria may still be useful for demonstrating the effect of a particular agent. It is also necessary that a SEB be measured in tissues (or other sample material) accessible for multiple and sequential sampling and allow for development of appropriate quality control procedures. Some SEBs must have the potential for modulation by chemopreventive agents. Validation of SEBs for use in chemoprevention studies requires that a relationship between the marker and subsequent risk of cancer be established. Also, the assay reliability and accuracy for each SEB must be determined adequately in well-designed prospective studies.

Hormone receptor status of breast tumors in black, Hispanic, and non-Hispanic white women. An analysis of 13,239 cases

BACKGROUND

It has been postulated that different biologic characteristics of a tumor might account for at least a portion of the disparity in breast cancer survival for patients across racial and ethnic groups. The hormone receptor status of breast tumors is one characteristic with prognostic significance. Results of several studies indicate a higher proportion of estrogen receptor negative (ER-) breast tumors among black or Hispanic women compared with non-Hispanic whites. We investigated whether the association between race and ethnicity and the joint combination of ER and progesterone receptor (PR) status was independent of age and other tumor characteristics at diagnosis.

METHODS

Relevant data were obtained from 13,239 breast cancer cases identified as part of the 1990 Patient Care Evaluation Study of Breast Cancer.

RESULTS

In univariate analysis, the proportions of ER+PR+, ER+PR-, ER-PR+, and ER-PR- tumors among non-Hispanics whites were 59%, 15%, 6%, and 20%, respectively; among Hispanics the proportions were 58%, 12%, 8%, and 22%, respectively; and among blacks the proportions were 44%, 14%, 7%, and 35%, respectively. After controlling for age, tumor size, and histology, using polychotomous logistic regression, these was no difference in hormone-receptor status between Hispanic and non-Hispanic white women. However, ER-PR- tumors were more likely to occur in blacks than in non-Hispanic whites (odds ratio = 1.8, 95% confidence interval = 1.6, 2.1)

CONCLUSIONS

The results of this study corroborate differences in hormone-receptor status between non-Hispanic white and black women, but not between Hispanics. Future studies of breast cancer should examine differences in epidemiologic risk factors between blacks and whites stratified on ER/PR status.

Synergistic effect between alcohol and estrogen replacement therapy on risk of breast cancer differs by estrogen/progesterone receptor status in the Iowa Women's Health Study

Two cohort studies have reported that alcohol and estrogen replacement therapy (ERT) act synergistically to increase the incidence of breast cancer. Possible interactions between alcohol consumption and family history of breast cancer or body mass index were also reported in the Iowa Women's Health Study data. In the Iowa Women's Health Study cohort, alcohol appears to be associated only with estrogen receptor-negative (ER-)/progesterone receptor-negative (PR-) breast cancers. Therefore, we investigated whether the interactions between alcohol and other risk factors differ according to ER/PR status. In January 1986, participants completed a questionnaire that included alcohol intake and other information. Through 1992, 939 breast cancer cases occurred among 37,105 postmenopausal women at risk. Cox proportional hazards regression was used to compute adjusted relative risks and to test for multiplicative interactions. Relative risks of ER+/PR+, ER+/PR-, and ER-/PR- breast cancer for women who consumed > or = 4.0 g of ethanol/day and reported ever using ERT compared to abstainers who never used ERT were 1.8, 1.3, and 2.6, respectively. Relative risks of ER+/PR+, ER+/PR-, and ER-/PR- breast cancer associated with any alcohol intake and a positive family history of breast cancer compared to abstainers with no family history of breast cancer were 1.7, 0.8, and 3.1, respectively. Relative risks of ER+/PR+, ER+/PR-, and ER-/PR- breast cancer associated with the highest quintile of body mass index and drinking > or = 4.0 g of ethanol/day compared to abstainers in the lower four-fifths of body mass index were 0.9, 1.8, and 2.0, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary fat and risk of breast cancer according to hormone receptor status

The association of dietary fat with breast cancer in prospective cohort studies has generally been weak and not statistically significant. However, these studies have not considered whether the risk related to fat intake may differ according to estrogen or progesterone receptor status. Dietary habits and other breast cancer risk factors were assessed by mailed questionnaire in January 1986 in 34,388 postmenopausal Iowa women. Through 1991, 724 incident breast cancer cases were ascertained in this cohort using the Iowa cancer registry. Joint estrogen and progesterone receptor status was determined for 479 (66%) breast cancers. For tumors that were positive for both estrogen and progesterone receptors (ER+/PR+) (n = 329), age- and energy-adjusted relative risks for breast cancer adjusted from lowest to highest third of fat intake were 1.0, 1.05, and 1.22 (P trend = 0.14). Corresponding risks for ER+/PR- tumors (n = 75) were 1.0, 0.85, and 1.05 (P trend = 0.86) and for ER-/PR- tumors (n = 61) were 1.0, 1.06, and 0.73 (P trend = 0.68). Only 14 cases were classified as having ER-/PR+ tumors. Adjustment for other breast cancer risk factors did not appreciably alter these findings. There was a suggestion that dietary fat may be associated with ER+/PR+ breast cancers and not other breast cancers. These results are also consistent with an interpretation of no association between dietary fat with breast cancer, regardless of hormone receptor status. It has been suggested that etiological studies of breast cancer should investigate associations according to receptor status. This study provides evidence of a subset of breast cancers that may be related to dietary factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential properties of brush-border membrane vesicles from early and late proximal tubules of rat kidney

We describe the preparation and properties of BBM vesicles (BBMV) from the superficial and juxtamedullary rat renal cortex using Ca(2+)-precipitation method and/or by density gradient centrifugation. BBMV were characterized by the presence of BBM marker enzymes as distributed along microdissected proximal convoluted tubule and proximal straight tubules from superficial and juxtamedullary cortex. In tubules from both superficial and juxtamedullary cortex, the activities of gamma-glutamyltransferase and leucine aminopeptidase were 5-10 times higher in proximal straight tubules than in proximal convoluted tubule. The alkaline phosphatase was higher in proximal convoluted tubules than in straight tubules from superficial cortex, but it was lower in proximal convoluted than straight tubules from the juxtamedullary cortex. The Na+/Pi cotransport had higher Vmax and lower Km in BBMV from superficial cortex than from BBMV from juxtamedullary tissue. BBMV from superficial cortex separated on Percoll gradient showed a high activity of alkaline phosphatase and low activities of gamma-glutamyltransferase and leucine aminopeptidase. Conversely, BBM from juxtamedullary cortex separated into a major peak with very high activities of gamma-glutamyltransferase and leucine aminopeptidase, and lesser activity of alkaline phosphatase. These distinct BBMV fractions showed diverse Na+/Pi cotransport properties and BBM marker enzyme distributions. Thus, using the outlined methodology it is feasible to prepare BBMV derived predominantly from proximal convoluted tubules or from proximal straight tubules located in either superficial or deep cortical nephrons.

Alcohol consumption and colon and rectal cancer in postmenopausal women

The associations between alcohol and colon and rectal cancers were examined in the Iowa Women's Health Study. In January 1986, 41 837 postmenopausal women, aged 55-69, completed a questionnaire including usual alcohol intake and other information. Through December 1990, 237 incident colon and 75 rectal cancer cases occurred. Mantel-Haenszel age-adjusted relative risks (RR) and 95% confidence intervals (CI) for consumers of < 4.0 and > or = 4.0 g of alcohol per day compared to abstainers were 1.07 (0.61-1.89) and 1.27 (0.72-2.24) (P for trend = 0.46) for rectal cancer. Alcohol intake was inversely associated with distal colon cancer (RR for < 4.0 and > or = 4.0 g of alcohol per day were 0.64 and 0.69 respectively, P for trend = 0.04), which was specific to wine; however, no association was observed with proximal colon cancer (P for trend = 0.94). This is the only report of an inverse association between alcohol and colon cancer in women. Because gut physiology and alcohol metabolism differ between men and women, more research on the association between alcohol and colon cancer in women only, is warranted.

Does body fat distribution promote familial aggregation of adult onset diabetes mellitus and postmenopausal breast cancer?

Noninsulin-dependent diabetes mellitus and postmenopausal breast cancer share a number of risk factors, including obesity, increased waist-to-hip ratio, and a positive family history. If risk for these diseases is mediated through a familial tendency for abdominal obesity, then one might expect to see familial clustering of both diseases. We analyzed data from a prospective cohort study of 41,837 Iowa women age 55-69 years. Diabetes was not associated with incidence of breast cancer [relative risk (RR) = 0.97]. The association between family history of breast cancer and breast cancer incidence, however, was slightly modified by individual history of diabetes: a positive family history of breast cancer in the absence of baseline diabetes was associated with a relative risk of 1.36 [95% confidence interval (CI) = 1.08-1.70], whereas the presence of both factors was associated with a RR of 1.87 (95% CI = 0.93-3.76). Adjustment for waist-to-hip ratio greatly diminished this difference. Conversely, a family history of breast cancer was associated with a RR of 5-year diabetes mortality of 1.94 (95% CI = 1.17-3.24) that persisted after stratification by tertile of waist-to-hip ratio. No clear association of family history of breast cancer and waist-to-hip ratio for self-reported diabetes incidence was evident. These data are indicative of a complex interrelation between waist-to-hip ratio, familial predisposition, diabetes, and breast cancer.

Evidence for the formation of multiple types of acetaldehyde-haemoglobin adducts

Acetaldehyde readily reacted with red blood cells and isolated haemoglobin to form adducts. We examined acetaldehyde-haemoglobin reaction products, isolated from red blood cells incubated with acetaldehyde (AcH), for the presence of stable peptide-specific acetaldehyde adducts. Red blood cell incubations were with 20, 50, and 200 mM acetaldehyde for 3, 24 and 48 hr. Peptide-specific [14C]acetaldehyde modifications of Hb from each incubation were identified by tryptic peptide mapping procedures. Nine peptides had modifications and six were found in incubations with 20 mM acetaldehyde. Two of the peptides were acetaldehyde modifications of the Hb alpha- and beta-chain N-termini. Stability studies indicated that the remaining seven [14C]AcH-modified peptides did not result, as can occur under certain conditions, from the transfer of AcH on the N-termini of Hb to N-termini formed after trypsin digestion. An analysis of the relative amounts of [14C]AcH-peptide adducts indicated that at least two of the seven peptides had reactivities for AcH different than the N-termini of Hb; that is, at least two modified peptides differ from imidazolidine-type adducts formed on the N-termini. The presence of multiple modifications with different sensitivities for AcH adduct formation may be useful in developing markers of alcohol consumption.

Sugar, meat, and fat intake, and non-dietary risk factors for colon cancer incidence in Iowa women (United States)

To investigate the relation of dietary intakes of sucrose, meat, and fat, and anthropometric, lifestyle, hormonal, and reproductive factors to colon cancer incidence, data were analyzed from a prospective cohort study of 35,215 Iowa (United States) women, aged 55-69 years and without a history of cancer, who completed mailed dietary and other questionnaires in 1986. Through 1990, 212 incident cases of colon cancer were documented. Proportional hazards regression was used to adjust for age and other risk factors. Risk factors found to be associated significantly with colon cancer included: (i) sucrose-containing foods and beverages other than ice cream/milk; relative risks (RR) across the quintiles = 1.00, 1.73, 1.56, 1.54, and 2.00 (95% confidence intervals [CI] for quintiles two and five exclude 1.0); (ii) sucrose; RR across the quintiles = 1.00, 1.70, 1.81, 1.82, and 1.45 (CI for quintiles two through four exclude 1.0); (iii) height; RR = 1.23 for highest to lowest quintile (P for trend = 0.02); (iv) body mass index; RR = 1.41 for highest to lowest quintile (P for trend = 0.03); and (v) number of livebirths, RR = 1.59 for having had one to two livebirths and 1.80 for having had three or more livebirths compared with having had none (P for trend = 0.04). These data support hypotheses that sucrose intake or being tall or obese increases colon cancer risk; run contrary to the hypothesis that increased parity decreases risk; support previous findings of no association with demographic factors other than age, cigarette smoking, or use of oral contraceptives or estrogen replacement therapy; and raise questions regarding previous associations with meat, fat, protein, and physical activity.

Association of body fat distribution and family histories of breast and ovarian cancer with risk of postmenopausal breast cancer

The authors recently published data from a prospective cohort study of postmenopausal women (N Engl J Med 1992;326:1323-9) which suggested that a high waist/hip ratio was associated with a significantly increased risk of breast cancer in women with a positive family history of breast cancer. Since families with aggregations of breast and ovarian cancer demonstrate more consistent genetic linkage to markers on chromosome 17q than do families with breast cancer alone, the authors performed additional analyses to examine whether the previously observed associations with waist/hip ratio differed when family history of breast cancer was partitioned according to whether or not ovarian cancer was also present in a close relative. Between 1986 and 1990, 620 incident cases of breast cancer were identified in a cohort of 37,105 postmenopausal Iowa women. A family history of breast cancer in first-degree relatives was associated with a relative risk of 1.34 (95% confidence interval (CI) 1.07-1.69); a family history of both breast cancer and ovarian cancer was associated with a relative risk of 2.36 (95% CI 1.12-4.98). Consistent with the authors' findings after 4 years of follow-up, a high waist/hip ratio (> or = 80th percentile vs. < 80th percentile) was associated with increased risk of breast cancer in the presence of a family history of breast cancer (relative risk (RR) = 2.10, 95% CI 1.43-3.09) but not in the absence of a family history of breast cancer (RR = 1.12). The combination of a high waist/hip ratio with a family history of breast and ovarian cancer was associated with 4.83-fold increased risk (95% CI 1.55-15.1). Neither a family history of breast cancer nor a family history of ovarian cancer was associated with significantly increased risk in the absence of a high waist/hip ratio.

Alcohol consumption and postmenopausal endometrial cancer: results from the Iowa Women's Health Study

At least three case-control studies have examined the association between alcohol consumption and endometrial cancer; two studies showed inverse associations, and a third a positive association. To our knowledge, no prospective studies of this association have been reported. The association between alcohol and endometrial cancer was examined in the Iowa Women's Health Study (United States), a prospective study of postmenopausal women. Information on alcohol consumption and other variables was obtained through a mailed questionnaire in January 1986. Through December 1990, 167 incident endometrial cancer cases occurred in the at-risk cohort of 25,170 women. Multivariate-adjusted relative risks (RR) and 95 percent confidence intervals (CI) were computed using Cox proportional hazards regression controlling for age, body mass index (BMI), parity, age at menopause, and noncontraceptive estrogen use, and to determine multiplicative interactions. The RRs of endometrial cancer associated with < 4.0 and > or = 4.0 g of alcohol per day compared with abstainers were 0.7 (CI = 0.5-1.1) and 1.0 (CI = 0.7-1.6), respectively. No statistically significant association between endometrial cancer and consumption of either beer, wine, or liquor was observed. There was no interaction between alcohol and any other endometrial cancer risk factors, including BMI or noncontraceptive estrogen use. These data do not support an association between alcohol and endometrial cancer among postmenopausal women.

The identification and partial characterization of acetaldehyde adducts of hemoglobin occurring in vivo: a possible marker of alcohol consumption

Chromatographic, peptide mapping and mass spectrometric analysis were used to examine hemoglobin (Hb) from heavy drinkers and abstainers for alcohol consumption-related modifications. Heavy drinker and abstainer hemoglobin samples contained similar amounts of glycosylated Hb and significantly different (p < 0.05) amounts of "fast" hemoglobin. The presence of higher amounts of "fast" Hb in heavy drinker relative to abstainer samples suggested the presence of alcohol-consumption related modifications. To further examine Hb for modifications, tryptic peptides of the "fast" hemoglobin HbA1c were isolated and analyzed by plasma desorption mass spectrometry (PDMS). [14C]acetaldehyde (AcH)-Hb was synthesized in vivo for use as a standard. Specific peptides were chosen based on co-migration with radiolabeled peptides from a tryptic digest of the [14C]acetaldehyde-Hb. The masses obtained by PDMS for two heavy drinker peptides were identical to two radiolabeled peptides; the two pairs of peptides co-migrated on HPLC. A comparison of the observed mass for the peptides with the theoretical masses for acetaldehyde-modified Hb peptides suggested that the peptides were AcH-modified alpha and beta chain N-termini of Hb. The modified peptides were found in five of six heavy drinker samples. This is the first description of site-specific AcH-Hb adducts occurring in vivo. The routine detection of such adducts has potential for characterizing usual alcohol intake.

Increased risk of breast cancer with alcohol consumption in postmenopausal women

The association between breast cancer incidence and alcohol consumption among postmenopausal women was examined in the Iowa Women's Health Study. In January 1986, a cohort of 41,837 postmenopausal women, aged 55-69 years, completed a questionnaire that included alcohol intake and other information. Through December 1989, 493 incident breast cancer cases were identified. Age-adjusted relative risks of consumption of less than 1.5, 1.5-4.9, 5.0-14.9, and 15.0 g or more of alcohol per day compared with abstention were 1.08, 1.10, 1.08, and 1.28, respectively (p for trend = 0.11). After controlling for age, body mass index, age at first livebirth, age at menarche, and family history of breast cancer, the relative risks were 1.18, 1.20, 1.25, and 1.46 (p for trend = 0.04). Multivariate modeling, using Cox proportional hazards regression, revealed a significant multiplicative interaction between alcohol intake and noncontraceptive estrogen use. The relative risks of breast cancer associated with average daily alcohol consumption of 5.0-14.9 and 15.0 g or more were 1.88 (95% confidence interval 1.30-2.72) and 1.83 (95% confidence interval 1.18-2.85), respectively, among ever-users of estrogen; no association between alcohol and breast cancer was observed among never-users of estrogen.

The formation of stable acetaldehyde-hemoglobin adducts in a red blood cell model

The formation of stable hemoglobin adducts was examined (in the absence of an added reducing agent) in metabolizing red blood cells (RBCs) exposed to micromolar concentrations of acetaldehyde for up to 48 hours in vitro. The rapid disappearance of acetaldehyde due to oxidation by RBC aldehyde dehydrogenase was prevented by pretreating the cells with the inhibitor cyanamide. The RBCs remained viable for 48 hours (37 degrees C) as determined by cell hemolysis and glycolytic activity. [14C]acetaldehyde-modified hemoglobin was assessed in untreated and in cyanamide-pretreated cells. In untreated cells, after 3 hours of exposure to 50 and 200 nmol/ml of [14C]acetaldehyde, the molar ratios of acetaldehyde to hemoglobin were 0.00069 and 0.0038, respectively; [14C]acetaldehyde concentrations decreased to less than 4% of the initial levels within 3 hours. In cyanamide-pretreated RBCs, the molar ratios of acetaldehyde bound to hemoglobin ranged from 0.0013 after 3 hours of exposure to 20 nmol/ml [14C]acetaldehyde up to 0.039 after 48 hours of exposure to 200 nmol/ml [14C]acetaldehyde. Following tryptic digestion of [14C]acetaldehyde-hemoglobin and separation of peptides by high-performance liquid chromatography, significant incorporation of [14C]acetaldehyde was observed in nine peptides. Modifications of the labeled peptides remain to be characterized.

Role of cAMP-phosphodiesterase isozymes in pathogenesis of murine nephrogenic diabetes insipidus

To test the hypothesis that rapid adenosine 3',5'-cyclic monophosphate (cAMP) catabolism via cyclic 3',5'-nucleotide phosphodiesterase (PDE) is a cause of the unresponsiveness to vasopressin (VP) in mice with hereditary nephrogenic diabetes insipidus (NDI), we investigated properties of PDEs and other aspects of the VP-dependent cAMP-signaling system in segments of collecting ducts [inner medullary (IMCD), cortical (CCD), and outer medullary (OMCD) ducts] microdissected from control mice and mice with NDI. The activity of cAMP-PDE, but not of cGMP-PDE, was markedly higher in IMCD (+109%), and to a lesser degree in OMCD (+41%) and CCD (+27%), of NDI mice than in normal controls. The cAMP-PDE in IMCD of NDI mice was more sensitive to inhibition by the PDE isozyme-specific inhibitors rolipram and cilostamide, but not by 3-isobutyl-1-methylxanthine, than was the cAMP-PDE in controls. Levels of cAMP in intact IMCD and CCD from NDI mice completely failed to increase in response to 10(-6) M VP. Incubation with rolipram alone, but not with cilostamide alone, restored VP-dependent cAMP accumulation in IMCD of NDI mice to the levels found in control mice; addition of cilostamide further enhanced the effect of rolipram. Analogous (but quantitatively lesser) anomalies of the VP-dependent cAMP system, including the effects of PDE inhibitors, were observed also in CCD of NDI mice. However, the activity of VP-stimulated adenylate cyclase assayed in permeabilized IMCD did not differ in NDI and control mice. These results indicate that anomalously high activities of low-Km cAMP-PDE isozymes account for the failure of collecting ducts of NDI mice to increase cAMP levels in response in VP.(ABSTRACT TRUNCATED AT 250 WORDS)

The association of body fat distribution with lifestyle and reproductive factors in a population study of postmenopausal women

We examined the cross-sectional association of fat distribution with a number of lifestyle and reproductive factors in a random sample of 40,980 postmenopausal women, aged 55 to 69 years. The relationship of weight history with current fat distribution was also explored. Body fat distribution, defined by the ratio of waist-to-hip circumferences (WHR), was most strongly related to body mass index (BMI). WHR was also significantly and negatively associated with physical activity, alcohol consumption, and education, and was significantly positively associated with age, cigarette smoking, and a number of reproductive factors, such as history of infertility, number of live births, age at first live birth, and replacement estrogen use. WHR was not related to past BMIs, after adjusting for current body mass. The best-fit final regression model included (beta +/- s.e.) age (0.003 +/- 0.0001), BMI (0.02 +/- 0.0005), a curvilinear term for BMI (-0.0002 +/- 0.00001), greater than high school education (-0.007 +/- 0.001), cigarette smoking (0.02 +/- 0.001), alcohol drinker (-0.005 +/- 0.001), and number of live births (0.001 +/- 0.0002). The model R2 was 0.21. BMI (R2 = 0.18) and age (R2 = 0.02) accounted for most of the variation in WHR. The association of these lifestyle and reproductive factors with WHR suggests that the deposition of fat in the abdominal versus the gluteal region may be influenced somewhat by factors other than overall adiposity and genetics.

Increased incidence of carcinoma of the breast associated with abdominal adiposity in postmenopausal women

Epidemiologic studies have established that increased body weight is associated with a greater incidence of breast cancer in postmenopausal women. The authors hypothesized that abdominal adiposity further increases risk of postmenopausal breast cancer. They therefore investigated the waist-to-hip circumference ratio in relation to breast cancer incidence in a nested case-control study of 41,837 postmenopausal Iowa women aged 55-69 years. Women were recruited through a mail survey in January 1986 and were asked to have someone measure their body circumferences using a paper tape measure and written instructions. Cancer incidence was ascertained using a statewide cancer registry. A total of 229 incident breast cancers occurred among at-risk women during the first 2 years of follow-up (1986-1987). Compared with randomly selected controls (n = 1,839), women with incident breast cancer had a higher age-adjusted mean waist-to-hip ratio (by 0.013 units, p = 0.030), as well as greater mean weight (by 1.7 kg, p = 0.07), body mass index (by 0.6 kg/m2, p = 0.08), and weight gain since age 18 (by 2.7 kg, p less than 0.01). In multiple logistic regression models, age and current body mass index were significant effect modifiers of the association between the waist-to-hip ratio and breast cancer. A two-standard deviation increase in the waist-to-hip ratio (0.168 units) was associated with no increase in the relative risk of breast cancer in younger and lighter postmenopausal women. However, in older, heavier postmenopausal women, the same increase in the waist-to-hip ratio carried greater than a twofold excess relative risk. Adjustment for other breast cancer risk factors did not materially alter this finding. Two plausible explanations for elevated breast cancer incidence in women with abdominal adiposity include 1) increased concentrations of non-protein-bound estrogens due to reduced sex hormone binding globulin, or 2) increased conversion of adrenal androgens to estrone with abdominal adiposity.

cAMP-binding proteins in medullary tubules from rat kidney: effect of ADH

Little is known of the regulatory steps in the cellular action of vasopressin (AVP) on the renal epithelium, subsequent to the cAMP generation. We studied cAMP-binding proteins in the medullary collecting tubule (MCT) and the thick ascending limb of Henle's loop (MTAL) microdissected from the rat kidney by use of photoaffinity labeling. Microdissected tubules were homogenized and photoaffinity labeled by incubation with 1 microM 32P-labeled 8-azido-adenosine 3',5'-cyclic monophosphate (N3-8-[32P]-cAMP); the incorporated 32P was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Both in MCT and MTAL preparations, the analyses showed incorporation of N3-8-[32P]cAMP into two bands (Mr = 49,000 and Mr = 55,000) that comigrated with standards of the cAMP-dependent protein kinase regulatory subunits RI and RII. In MCT, most of the 32P (80%) was incorporated into RI, whereas in MTAL the 32P incorporated into RI and RII was equivalent. When freshly dissected MCT segments were incubated with 10(-12)-10(-6) M AVP, the subsequent photoaffinity labeling of RI with N3-8-[32P]cAMP was markedly diminished in a dose-dependent manner compared with controls. Our results suggest that cAMP binds in MCT and MTAL to regulatory subunits RI and RII of cAMP-dependent protein kinase. However, in MCT the dominant type of cAMP-dependent protein kinase appears to be type I. The outlined procedure is suitable to indirectly measure the occupancy of RI by endogenous cAMP generated in MCT cells in response to physiological levels (10(-12) M) of AVP.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ phosphorylation of proteins in MCTs microdissected from rat kidney: effect of AVP

Adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein phosphorylation is considered a key step in the cellular action of vasopressin (AVP) to regulate water permeability in collecting tubules. However, the proteins serving as a substrate(s) for phosphorylation in undisrupted cells have not yet been identified. In the present study, we developed a method for investigation of in situ phosphorylation of microdissected segments of medullary collecting tubules (MCT) from rat kidney. Incubation of microdissected MCT segments with low concentrations of saponin, "semipermeabilization," increased permeability of the membrane for ATP but did not allow leakage of macromolecules such as lactate dehydrogenase. This treatment also did not cause major disruption of cell structure, or impairment of AVP-sensitive adenylate cyclase. Incubation of semipermeabilized MCT with gamma-[32P]ATP resulted in incorporation of 32Pi into two major protein bands [band "A" of apparent molecular mass (Mr) approximately equal to 66 kDa, and band "B" of Mr approximately equal to 45 kDa] detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis and subsequent autoradiography. Similar incubation of tubules disrupted by hyposmotic solutions and a stronger detergent Triton X-100 resulted in 32Pi incorporation into multiple protein bands. Incubation of MCT with 1 microM AVP resulted in increased 32Pi radioactivity in band A and decreased 32Pi radioactivity in band B. These findings demonstrate a novel method for identification of endogenous protein substrate(s) for cAMP-dependent protein kinase and other protein kinases and phosphatases that are probably involved in post-cAMP steps in the cellular action of AVP in the intact cells of collecting tubules.

Evidence for beta adrenoceptors in proximal tubules. Isoproterenol-sensitive adenylate cyclase in pars recta of canine nephron

Observations in vivo suggest that catecholamines modulate reabsorptive functions of proximal tubules by acting on beta-adrenoceptors. However, beta-catecholamine binding sites or beta-adrenoceptor-sensitive adenylate cyclase (AdC) has not been found in segments of proximal tubules of rat, rabbit, or mouse kidney. In the present study, we investigated the responsiveness of AdC to catecholamines, [8-Arg]vasopressin (AVP), and to parathyroid hormone (PTH) in proximal convoluted tubules (PCT), proximal straight tubules (PST), and in late distal convoluted tubules (LDCT) microdissected from canine kidney. Isoproterenol (ISO) caused a marked and dose-dependent stimulation of AdC in PST (maximum: delta + 850%; half maximum stimulation at 10(-7) M ISO), but ISO had no effect on AdC in PCT. The AdC in both PCT and PST was markedly stimulated by PTH; AVP stimulated the AdC in LDCT but not in PST or in PCT. The stimulatory effect of 10(-5) M ISO in PST (delta + 725%) was significantly greater than in LDCT (delta + 307%); norepinephrine and epinephrine had stimulatory effects in PST similar to ISO. The stimulation of AdC in PST by ISO was blocked by propranolol and by beta 2-blocker ICI-118551. On the other hand, alpha-blocker phentolamine and beta 1-blocker metoprolol did not abolish the stimulation of AdC in PST by ISO. The accumulation of cAMP in intact PCT and PST incubated in vitro was stimulated by PTH both in PST and in PCT, but ISO elevated cAMP (delta + 683%) only in PST. Our results show that proximal tubules of canine nephron, PST but not PCT, contain beta-adrenoceptors of beta 2 subtype coupled to AdC. These observations provide direct evidence that the effects of catecholamines, either released from renal nerve endings or arriving from blood supply, can act directly on beta 2-adrenoceptors located in proximal tubules, and also suggest that at least some of the catecholamine effects in proximal tubules are mediated via cAMP generation.

The vasopressin-sensitive adenylate cyclase in collecting tubules and in thick ascending limb of Henle's loop of human and canine kidney

The major tubular effects of [8-Arg]vasopressin (AVP) in regulation of renal water excretion are initiated by stimulation of adenylate cyclase (AdC) coupled with V2 receptors. We explored whether the AVP-sensitive AdC is present in both collecting tubules and the thick ascending limb of Henle's loop of human and canine kidney. In cortical collecting tubule (CCT) and medullary collecting tubules (MCT) of human kidney, AdC was markedly stimulated by AVP [maximum change from basal level (delta), +2700%] and the the nonhormonal stimulatory agent forskolin (delta, +2000%). In human CCT, the effects of both compounds were synergistic. In contrast, AVP had no effect on AdC in either the medullary (MAL) or cortical (CAL) segment of the thick ascending limb of Henle's loop of human kidney; AVP also did not stimulate AdC in CAL or MAL in the presence of forskolin. Similar to that in the human kidney, in the canine kidney, AdC in CCT and MCT was markedly stimulated by AVP and forskolin (delta, +1000%), but AVP had no effect on AdC in CAL and MAL of the canine kidney. In intact tubules dissected from dog kidney and incubated in vitro, AVP markedly increased cAMP accumulation in MCT. AVP also elicited a small but detectable increase in cAMP accumulation in MAL. From these observations, we conclude that AVP-sensitive AdC is well developed in collecting tubules, but that AVP-sensitive AdC is absent in MAL and CAL of human kidney. Likewise, in canine nephron, the AVP-sensitive AdC of MAL and CAL is rudimentary or very labile. These findings suggest that the unresponsiveness of the AdC-cAMP system to AVP in segments of the thick ascending limb of Henle's loop may be a factor that accounts for a relatively low maximum osmotic concentration of urine which can be achieved by human or canine kidneys.