The advantages of UK Biobank's open-access strategy for health research

Ready access to health research studies is becoming more important as researchers, and their funders, seek to maximize the opportunities for scientific innovation and health improvements. Large-scale population-based prospective studies are particularly useful for multidisciplinary research into the causes, treatment and prevention of many different diseases. UK Biobank has been established as an open-access resource for public health research, with the intention of making the data as widely available as possible in an equitable and transparent manner. Access to UK Biobank's unique breadth of phenotypic and genetic data has attracted researchers worldwide from across academia and industry. As a consequence, it has enabled scientists to perform world-leading collaborative research. Moreover, open access to an already deeply characterized cohort has encouraged both public and private sector investment in further enhancements to make UK Biobank an unparalleled resource for public health research and an exemplar for the development of open-access approaches for other studies.

Polyoxometalate (POM) grafted grooved nanofibrous membranes for improved self-decontamination

Combining unique fiber morphologies with self-decontamination technologies can enhance degradation of toxic compounds on fibrous substrates.

Adherence to the Mediterranean diet and risk of bladder cancer in the EPIC cohort study

There is growing evidence of the protective role of the Mediterranean diet (MD) on cancer. However, to date no epidemiological study has investigated the influence of the MD on bladder cancer. We evaluated the association between adherence to the MD and risk of urothelial cell bladder cancer (UCC), according to tumor aggressiveness, in the European Prospective Investigation into Cancer and Nutrition (EPIC). The analysis included 477,312 participants, recruited from ten European countries between 1991 and 2000. Information from validated dietary questionnaires was used to develop a relative Mediterranean diet score (rMED), including nine dietary components. Cox regression models were used to assess the effect of the rMED on UCC risk, while adjusting for dietary energy and tobacco smoking of any kind. Stratified analyses were performed by sex, BMI, smoking status, European region and age at diagnosis. During an average follow-up of 11 years, 1,425 participants (70.9% male) were diagnosed with a first primary UCC. There was a negative but non-significant association between a high versus low rMED score and risk of UCC overall (HR: 0.84 [95% CI 0.69, 1.03]) and risk of aggressive (HR: 0.88 [95% CI 0.61, 1.28]) and non-aggressive tumors (HR: 0.78 [95% CI 0.54, 1.14]). Although there was no effect modification in the stratified analyses, there was a significant 34% (p = 0.043) decreased risk of UCC in current smokers with a high rMED score. In EPIC, the MD was not significantly associated with risk of UCC, although we cannot exclude that a MD may reduce risk in current smokers.

The effects of diet on circulating sex hormone levels in men

There is considerable epidemiological evidence that a Western-style diet may increase the risk of certain hormone-dependent conditions in men via its effects on hormone metabolism. Experimental evidence also suggests that dietary factors may exert subtle effects on hormone metabolism. Here we review the clinical and epidemiological evidence that diet is associated with circulating sex hormone levels in men. In comparison with factors such as age and BMI, nutrients do not appear to be strong determinants of sex hormone levels. Dietary intervention studies have not shown that a change in dietary fat and/or dietary fibre intake is associated with changes in circulating sex hormone concentrations over the short term. The data on the effects of dietary phyto-oestrogens on sex hormone levels in men are too limited for conclusions to be drawn. Observational studies between men from different dietary groups have shown that a vegan diet is associated with small but significant increases in sex-hormone-binding globulin and testosterone concentrations in comparison with meat-eaters. However, these studies have not demonstrated that variations in dietary composition have any long-term important effects on circulating bioavailable sex hormone levels in men. This lack of effect may be partly explained by the body's negative feedback mechanism, which balances out small changes in androgen metabolism in order to maintain a constant level of circulating bioavailable androgens. It appears, therefore, that future studies should look for dietary effects on the feedback mechanism itself, or on the metabolism of androgens within the target tissues.

Alcohol consumption and risk of type 2 diabetes in European men and women: influence of beverage type and body size The EPIC-InterAct study

OBJECTIVE

To investigate the association between alcohol consumption and type 2 diabetes, and determine whether this is modified by sex, body mass index (BMI) and beverage type.

DESIGN

Multicentre prospective case-cohort study.

SETTING

Eight countries from the European Prospective Investigation into Cancer and Nutrition cohort.

SUBJECTS

A representative baseline sample of 16 154 participants and 12 403 incident cases of type 2 diabetes.

INTERVENTIONS

Alcohol consumption assessed using validated dietary questionnaires.

MAIN OUTCOME MEASURES

Occurrence of type 2 diabetes based on multiple sources (mainly self-reports), verified against medical information.

RESULTS

Amongst men, moderate alcohol consumption was nonsignificantly associated with a lower incidence of diabetes with a hazard ratio (HR) of 0.90 (95% CI: 0.78-1.05) for 6.1-12.0 versus 0.1-6.0 g day(-1) , adjusted for dietary and diabetes risk factors. However, the lowest risk was observed at higher intakes of 24.1-96.0 g day(-1) with an HR of 0.86 (95% CI: 0.75-0.98). Amongst women, moderate alcohol consumption was associated with a lower incidence of diabetes with a hazard ratio of 0.82 (95% CI: 0.72-0.92) for 6.1-12.0 g day(-1) (P interaction gender <0.01). The inverse association between alcohol consumption and diabetes was more pronounced amongst overweight (BMI ≥ 25 kg m(-2) ) than normal-weight men and women (P interaction < 0.05). Adjusting for waist and hip circumference did not alter the results for men, but attenuated the association for women (HR=0.90, 95% CI: 0.79-1.03 for 6.1-12.0 g day(-1) ). Wine consumption for men and fortified wine consumption for women were most strongly associated with a reduced risk of diabetes.

CONCLUSIONS

The results of this study show that moderate alcohol consumption is associated with a lower risk of type 2 diabetes amongst women only. However, this risk reduction is in part explained by fat distribution. The relation between alcohol consumption and type 2 diabetes was stronger for overweight than normal-weight women and men.

Helicobacter pylori infection assessed by ELISA and by immunoblot and noncardia gastric cancer risk in a prospective study: the Eurgast-EPIC project

BACKGROUND

In epidemiological studies, Helicobacter pylori infection is usually detected by enzyme-linked immunosorbent assay (ELISA). However, infection can spontaneously clear from the mucosa during the progression of atrophy and could lead to substantial under-detection of infection and underestimation of its effect on gastric cancer (GC) risk. Antibodies detected by western blot are known to persist longer after the loss of the infection.

METHODS

In a nested case-control study from the Eurogast-EPIC cohort, including 88 noncardia GC cases and 338 controls, we assessed the association between noncardia GC and H. pylori infection comparing antibodies detected by western blot (HELICOBLOT2.1) to those detected by ELISA (Pyloriset EIA-GIII(®)).

RESULTS

By immunoblot, 82 cases (93.2%) were H. pylori positive, 10 of these cases (11.4%) were negative by ELISA and only 6 cases (6.8%) were negative by both ELISA and immunoblot. Multivariable odds ratio (OR) for noncardia GC comparing immunoglobulin G positive versus negative by ELISA was 6.8 [95% confidence interval (CI) 3.0-15.1], and by immunoblot, the OR was 21.4 (95% CI 7.1-64.4).

CONCLUSIONS

Using a western blot assay, nearly all noncardia GC were classified as H. pylori positive and the OR was more than threefold higher than the OR assessed by ELISA, supporting the hypothesis that H. pylori infection is a necessary condition for noncardia GC.

Inflammation marker and risk of pancreatic cancer: a nested case-control study within the EPIC cohort

Background:

Established risk factors for pancreatic cancer include smoking, long-standing diabetes, high body fatness, and chronic pancreatitis, all of which can be characterised by aspects of inflammatory processes. However, prospective studies investigating the relation between inflammatory markers and pancreatic cancer risk are scarce.

Methods:

We conducted a nested case–control study within the European Prospective Investigation into Cancer and Nutrition, measuring prediagnostic blood levels of C-reactive protein (CRP), interleukin-6 (IL-6), and soluble receptors of tumour necrosis factor-α (sTNF-R1, R2) in 455 pancreatic cancer cases and 455 matched controls. Odds ratios (ORs) were estimated using conditional logistic regression models.

Results:

None of the inflammatory markers were significantly associated with risk of pancreatic cancer overall, although a borderline significant association was observed for higher circulating sTNF-R2 (crude OR=1.52 (95% confidence interval (CI) 0.97–2.39), highest vs lowest quartile). In women, however, higher sTNF-R1 levels were significantly associated with risk of pancreatic cancer (crude OR=1.97 (95% CI 1.02–3.79)). For sTNF-R2, risk associations seemed to be stronger for diabetic individuals and those with a higher BMI.

Conclusion:

Prospectively, CRP and IL-6 do not seem to have a role in our study with respect to risk of pancreatic cancer, whereas sTNF-R1 seemed to be a risk factor in women and sTNF-R2 might be a mediator in the risk relationship between overweight and diabetes with pancreatic cancer. Further large prospective studies are needed to clarify the role of proinflammatory proteins and cytokines in the pathogenesis of exocrine pancreatic cancer.

Primary brain tumours and specific serum immunoglobulin E: a case-control study nested in the European Prospective Investigation into Cancer and Nutrition cohort

BACKGROUND

Case-control studies suggest that patients with allergic diseases have a lower risk of developing glioma but not meningioma or schwannoma. However, those data can be differentially biased. Prospective studies with objective measurements of immunologic biomarkers, like immunoglobulin E (IgE), in blood obtained before cancer diagnosis could help to clarify whether an aetiological association exists.

METHODS

The present case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) measured specific serum IgE as a biomarker for the most common inhalant allergens in 275 glioma, 175 meningioma and 49 schwannoma cases and 963 matched controls using the ImmunoCAP specific IgE test. Subjects with an IgE level ≥0.35 kUA/l (kilo antibody units per litre) were classified as sensitized by allergens. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by adjusted conditional logistic regression models for each tumour subtype. The effect of dose-response relationship was assessed in five increasing IgE level categories to estimate P-values for trend.

RESULTS

The risk of glioma was inversely related to allergic sensitization (OR = 0.73; 95% CI 0.51-1.06), especially pronounced in women (OR = 0.53; 95% CI 0.30-0.95). In dose-response analyses, for high-grade glioma, the lowest OR was observed in sera with the highest IgE levels (P for trend = 0.04). No association was seen for meningioma and schwannoma.

CONCLUSION

The results, based on serum samples prospectively collected in a cohort study, provide some support for the hypothesis that individuals with allergic sensitization are at reduced risk of glioma and confirm results from previous case-control studies.

Fluid intake and incidence of renal cell carcinoma in UK women

Background:

It has been suggested that the apparent protective effect of alcohol intake on renal cell carcinoma may be due to the diluting effect of carcinogens by a high total fluid intake. We assessed the association between intakes of total fluids and of specific beverages on the risk of renal cell carcinoma in a large prospective cohort of UK women.

Methods:

Information on beverage consumption was obtained from a questionnaire sent ∼3 years after recruitment into the Million Women Study. Cox proportional hazards models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for renal cell carcinoma associated with beverage consumption adjusted for age, region of residence, socioeconomic status, smoking, and body mass index.

Results:

After an average of 5.2 years of follow-up, 588 cases of renal cell carcinoma were identified among 779 369 women. While alcohol intake was associated with a reduced risk of renal cell carcinoma (RR for ⩾2 vs <1 drink per day: 0.76; 95% CI: 0.61–0.96; P for trend=0.02), there was no association with total fluid intake (RR for ⩾12 vs <7 drinks per day: 1.15; 95% CI: 0.91–1.45; P for trend=0.3) or with intakes of specific beverages.

Conclusions:

The apparent protective effect of alcohol on the risk of renal cell carcinoma is unlikely to be related to a high fluid intake.

Oral contraceptives, reproductive history and risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

Oral contraceptive use and reproductive factors may initiate long-term changes to the hormonal milieu and thereby, possibly influence colorectal cancer risk.

METHODS

We examined the association of hormonal and reproductive factors with risk of colorectal cancer among 337,802 women in the European Prospective Investigation into Cancer and Nutrition, of whom 1878 developed colorectal cancer.

RESULTS

After stratification for center and age, and adjustment for body mass index, smoking, diabetes mellitus, physical activity and alcohol consumption, ever use of oral contraceptives was marginally inversely associated with colorectal cancer risk (hazard ratio (HR), 0.92; 95% confidence interval (CI), 0.83-1.02), although this association was stronger among post-menopausal women (HR, 0.84; 95% CI: 0.74-0.95). Duration of oral contraceptive use and reproductive factors, including age at menarche, age at menopause, type of menopause, ever having an abortion, parity, age at first full-term pregnancy and breastfeeding, were not associated with colorectal cancer risk.

CONCLUSION

Our findings provide limited support for a potential inverse association between oral contraceptives and colorectal cancer risk.

Serum concentrations of vitamin B12 and folate in British male omnivores, vegetarians and vegans: results from a cross-sectional analysis of the EPIC-Oxford cohort study

BACKGROUND/OBJECTIVES

Vegans, and to a lesser extent vegetarians, have low average circulating concentrations of vitamin B12; however, the relation between factors such as age or time on these diets and vitamin B12 concentrations is not clear. The objectives of this study were to investigate differences in serum vitamin B12 and folate concentrations between omnivores, vegetarians and vegans and to ascertain whether vitamin B12 concentrations differed by age and time on the diet.

SUBJECTS/METHODS

A cross-sectional analysis involving 689 men (226 omnivores, 231 vegetarians and 232 vegans) from the European Prospective Investigation into Cancer and Nutrition Oxford cohort.

RESULTS

Mean serum vitamin B12 was highest among omnivores (281, 95% CI: 270-292 pmol/l), intermediate among vegetarians (182, 95% CI: 175-189 pmol/l) and lowest among vegans (122, 95% CI: 117-127 pmol/l). In all, 52% of vegans, 7% of vegetarians and one omnivore were classified as vitamin B12 deficient (defined as serum vitamin B12 <118 pmol/l). There was no significant association between age or duration of adherence to a vegetarian or a vegan diet and serum vitamin B12. In contrast, folate concentrations were highest among vegans, intermediate among vegetarians and lowest among omnivores, but only two men (both omnivores) were categorized as folate deficient (defined as serum folate <6.3 nmol/l).

CONCLUSION

Vegans have lower vitamin B12 concentrations, but higher folate concentrations, than vegetarians and omnivores. Half of the vegans were categorized as vitamin B12 deficient and would be expected to have a higher risk of developing clinical symptoms related to vitamin B12 deficiency.

Cancer incidence in British vegetarians

Background:

Few prospective studies have examined cancer incidence among vegetarians.

Methods:

We studied 61 566 British men and women, comprising 32 403 meat eaters, 8562 non-meat eaters who did eat fish (‘fish eaters’) and 20 601 vegetarians. After an average follow-up of 12.2 years, there were 3350 incident cancers of which 2204 were among meat eaters, 317 among fish eaters and 829 among vegetarians. Relative risks (RRs) were estimated by Cox regression, stratified by sex and recruitment protocol and adjusted for age, smoking, alcohol, body mass index, physical activity level and, for women only, parity and oral contraceptive use.

Results:

There was significant heterogeneity in cancer risk between groups for the following four cancer sites: stomach cancer, RRs (compared with meat eaters) of 0.29 (95% CI: 0.07–1.20) in fish eaters and 0.36 (0.16–0.78) in vegetarians, P for heterogeneity=0.007; ovarian cancer, RRs of 0.37 (0.18–0.77) in fish eaters and 0.69 (0.45–1.07) in vegetarians, P for heterogeneity=0.007; bladder cancer, RRs of 0.81 (0.36–1.81) in fish eaters and 0.47 (0.25–0.89) in vegetarians, P for heterogeneity=0.05; and cancers of the lymphatic and haematopoietic tissues, RRs of 0.85 (0.56–1.29) in fish eaters and 0.55 (0.39–0.78) in vegetarians, P for heterogeneity=0.002. The RRs for all malignant neoplasms were 0.82 (0.73–0.93) in fish eaters and 0.88 (0.81–0.96) in vegetarians (P for heterogeneity=0.001).

Conclusion:

The incidence of some cancers may be lower in fish eaters and vegetarians than in meat eaters.

Relationship of alcohol intake and sex steroid concentrations in blood in pre- and post-menopausal women: the European Prospective Investigation into Cancer and Nutrition

OBJECTIVE

Women with a moderate intake of alcohol have higher concentrations of sex steroids in serum, and higher risk of developing breast cancer, compared to non-drinkers. In the present study, we investigate the relationships between alcohol consumption and serum levels of sex steroids and sex-hormone binding globulin (SHBG) in 790 pre- and 1,291 post-menopausal women, who were part of the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

Serum levels of testosterone (T), androstenedione (Delta4), dehydroepiandrosterone sulphate (DHEAS), estrone (E1), estradiol (E2) and SHBG were measured by direct immunoassays. Free T (fT) and free E2 (fE2) were calculated according to mass action laws. Current alcohol intake exposure to alcohol was assessed from dietary questionnaires.

RESULTS

Pre-menopausal women who consumed more than 25 g/day of alcohol had about 30% higher DHEAS, T and fT, 20% higher Delta4 and about 40% higher E1, concentrations compared to women who were non-consumers. E2, fE2 and SHBG concentrations showed no association with current alcohol intake. In post-menopausal women, DHEAS, fT, T, Delta4, and E1 concentrations were between 10% and 20% higher in women who consumed more than 25 g/day of alcohol compared to non-consumers. E2 or fE2 were not associated with alcohol intake at all. SHBG levels were about 15% lower in alcohol consumers compared to non-consumers.

CONCLUSION

This study supports the hypothesis of an influence of alcohol intake on sex hormone concentrations in blood.

Diet, serum insulin-like growth factor-I and IGF-binding protein-3 in European women

OBJECTIVE

The aim of this study was to examine the relationship of diet with serum insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 in women.

DESIGN

Cross-sectional study.

SETTING AND SUBJECTS

The population are 2109 women who were control subjects in a case-control study of breast cancer nested in the European Prospective Investigation into Cancer and Nutrition. Control subjects were randomly chosen among risk sets consisting of female cohort members alive and free of cancer (except non-melanoma skin cancer) at the time of diagnosis of the index case. Matching criteria were age at enrolment, follow-up time, time of the day of blood collection and study centre. Diet was measured through validated questionnaires. Serum hormone concentrations were measured by enzyme-linked immunosorbent assays. The relationship between serum IGF-I, IGFBP-3, and intake of nutrients and foods was explored by linear regression in models adjusted for energy intake, age, body mass index, smoking, physical activity, centre and laboratory batch.

RESULTS

Serum IGF-I levels were positively related to protein intake (P(trend)<0.001), but not related to energy, fat or carbohydrate intake. Positive relationships were observed with the intake of milk (P(trend)=0.007), calcium (P(trend)<0.001), magnesium (P(trend)=0.003), phosphorus (P(trend)<0.001), potassium (P(trend)=0.002), vitamin B6 (P(trend)=0.03), vitamin B2 (P(trend)=0.001) and inverse relationships with vegetables (P(trend)=0.02) and beta-carotene (P(trend)=0.02). IGFBP-3 was not related with most of the nutrients and foods in this study.

CONCLUSIONS

In this population, circulating IGF-I is modestly related with the intake of protein and minerals, and with milk and cheese, while IGFBP-3 does not appear to be related with diet.

Multi-factor dimensionality reduction applied to a large prospective investigation on gene-gene and gene-environment interactions

It is becoming increasingly evident that single-locus effects cannot explain complex multifactorial human diseases like cancer. We applied the multi-factor dimensionality reduction (MDR) method to a large cohort study on gene-environment and gene-gene interactions. The study (case-control nested in the EPIC cohort) was established to investigate molecular changes and genetic susceptibility in relation to air pollution and environmental tobacco smoke (ETS) in non-smokers. We have analyzed 757 controls and 409 cases with bladder cancer (n=124), lung cancer (n=116) and myeloid leukemia (n=169). Thirty-six gene variants (DNA repair and metabolic genes) and three environmental exposure variables (measures of air pollution and ETS at home and at work) were analyzed. Interactions were assessed by prediction error percentage and cross-validation consistency (CVC) frequency. For lung cancer, the best model was given by a significant gene-environment association between the base excision repair (BER) XRCC1-Arg399Gln polymorphism, the double-strand break repair (DSBR) BRCA2-Asn372His polymorphism and the exposure variable 'distance from heavy traffic road', an indirect and robust indicator of air pollution (mean prediction error of 26%, P<0.001, mean CVC of 6.60, P=0.02). For bladder cancer, we found a significant 4-loci association between the BER APE1-Asp148Glu polymorphism, the DSBR RAD52-3'-untranslated region (3'-UTR) polymorphism and the metabolic gene polymorphisms COMT-Val158Met and MTHFR-677C>T (mean prediction error of 22%, P<0.001, mean CVC consistency of 7.40, P<0.037). For leukemia, a 3-loci model including RAD52-2259C>T, MnSOD-Ala9Val and CYP1A1-Ile462Val had a minimum prediction error of 31% (P<0.001) and a maximum CVC of 4.40 (P=0.086). The MDR method seems promising, because it provides a limited number of statistically stable interactions; however, the biological interpretation remains to be understood.

IGF-I, IGFBP-3 and breast cancer risk in women: The European Prospective Investigation into Cancer and Nutrition (EPIC)

Blood concentrations of insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) have recently been associated with breast cancer risk, notably in women who developed breast cancer at a young age. Prospective studies published so far, however, were relatively small and odds ratio (OR) estimates imprecise. We present the results of a large prospective case-control study nested within the European Prospective Investigation into Cancer and Nutrition on total IGF-I, IGFBP-3 and breast cancer risk including 1081 incident cases of invasive breast cancer and 2098 matched control subjects. Increasing IGF-I and IGFBP-3 concentrations were associated with a significant increase in breast cancer risk in women who developed breast cancer after 50 years of age (highest vs lowest quintile OR 1.38 (95% confidence interval (CI) 1.02-1.86), P = 0.01, and 1.44 (95% CI 1.04-1.98), P = 0.01, respectively), but no relationship was observed in younger women (OR = 1.03 (95% CI 0.60-1.77), P = 0.81 for IGF-I, and OR = 0.92 (95% CI 0.50-1.70), P = 0.69 for IGFBP-3). There was, however, significant heterogeneity in the relationship of breast cancer with serum IGF-I and IGFBP-3 levels depending on the time interval between blood donation and tumor diagnosis. A reduction in breast cancer risk with increasing IGF-I concentrations was observed in cases with a diagnosis of cancer less than 2 years after blood donation, (OR = 0.76 (95% CI 0.57-1.03)), while an increase in risk was observed for women with a later diagnosis (above or equal to two years after blood collection, OR = 1.51 (95% CI 1.19-1.91)). A similar pattern was observed for IGFBP-3. This study confirms previous findings for an association of serum IGF-I and IGFBP-3 concentrations with breast cancer risk, particularly for women with a later diagnosis of cancer, but it does not support the hypothesis of an involvement of IGF-I in younger women.

Polymorphisms of genes coding for insulin-like growth factor 1 and its major binding proteins, circulating levels of IGF-I and IGFBP-3 and breast cancer risk: results from the EPIC study

Insulin-like growth factor I (IGF-I) stimulates cell proliferation and can enhance the development of tumours in different organs. Epidemiological studies have shown that an elevated level of circulating IGF-I is associated with increased risk of breast cancer, as well as of other cancers. Most of circulating IGF-I is bound to an acid-labile subunit and to one of six insulin-like growth factor binding proteins (IGFBPs), among which the most important are IGFBP-3 and IGFBP-1. Polymorphisms of the IGF1 gene and of genes encoding for the major IGF-I carriers may predict circulating levels of IGF-I and have an impact on cancer risk. We tested this hypothesis with a case–control study of 807 breast cancer patients and 1588 matched control subjects, nested within the European Prospective Investigation into Cancer and Nutrition. We genotyped 23 common single nucleotide polymorphisms in IGF1, IGFBP1, IGFBP3 and IGFALS, and measured serum levels of IGF-I and IGFBP-3 in samples of cases and controls. We found a weak but significant association of polymorphisms at the 5′ end of the IGF1 gene with breast cancer risk, particularly among women younger than 55 years, and a strong association of polymorphisms located in the 5′ end of IGFBP3 with circulating levels of IGFBP-3, which confirms previous findings. Common genetic variation in these candidate genes does not play a major role in altering breast cancer risk in Caucasians.

Postmenopausal serum androgens, oestrogens and breast cancer risk: the European prospective investigation into cancer and nutrition

Considerable experimental and epidemiological evidence suggests that elevated endogenous sex steroids - notably androgens and oestrogens - promote breast tumour development. In spite of this evidence, postmenopausal androgen replacement therapy with dehydroepiandrosterone (DHEA) or testosterone has been advocated for the prevention of osteoporosis and improved sexual well-being. We have conducted a case-control study nested within the European Prospective Investigation into Cancer and Nutrition. Levels of DHEA sulphate (DHEAS), (Delta4-androstenedione), testosterone, oestrone, oestradiol and sex-hormone binding globulin (SHBG) were measured in prediagnostic serum samples of 677 postmenopausal women who subsequently developed breast cancer and 1309 matched control subjects. Levels of free testosterone and free oestradiol were calculated from absolute concentrations of testosterone, oestradiol and SHBG. Logistic regression models were used to estimate relative risks of breast cancer by quintiles of hormone concentrations. For all sex steroids -the androgens as well as the oestrogens - elevated serum levels were positively associated with breast cancer risk, while SHBG levels were inversely related to risk. For the androgens, relative risk estimates (95% confidence intervals) between the top and bottom quintiles of the exposure distribution were: DHEAS 1.69 (1.23-2.33), androstenedione 1.94 (1.40-2.69), testosterone 1.85 (1.33-2.57) and free testosterone 2.50 (1.76-3.55). For the oestrogens, relative risk estimates were: oestrone 2.07 (1.42-3.02), oestradiol 2.28 (1.61-3.23) and free oestradiol (odds ratios 2.13 (1.52-2.98)). Adjustments for body mass index or other potential confounding factors did not substantially alter any of these relative risk estimates. Our results have shown that, among postmenopausal women, not only elevated serum oestrogens but also serum androgens are associated with increased breast cancer risk. Since DHEAS and androstenedione are largely of adrenal origin in postmenopausal women, our results indicated that elevated adrenal androgen synthesis is a risk factor for breast cancer. The results from this study caution against the use of DHEA(S), or other androgens, for postmenopausal androgen replacement therapy.

Long-term weight change and breast cancer risk: the European prospective investigation into cancer and nutrition (EPIC)

We examined prospectively the association between weight change during adulthood and breast cancer risk, using data on 1358 incident cases that developed during 5.8 years of follow-up among 40 429 premenopausal and 57 923 postmenopausal women from six European countries, taking part in the European prospective investigation into cancer and nutrition study. Multivariate Cox regression models were used to calculate hazard ratios according to weight change (kg), defined as the weight difference between age at enrolment and age 20 adjusted for other risk factors. Changes in weight were not associated with premenopausal breast cancer risk. In postmenopausal women, weight gain was positively associated with breast cancer risk only among noncurrent hormone replacement therapy (HRT) users (P-trend ⩽0.0002). Compared to women with a stable weight (±2 kg), the relative risk for women who gained 15–20 kg was 1.50 (95% confidence interval (CI) 1.06–2.13). The pooled RR per weight gain increment of 5 kg was 1.08 (95% CI 1.04–1.12). Weight gain was not associated with breast cancer risk in current HRT users, although, overall, these women experienced a much higher risk of breast cancer compared with nonusers. Our findings suggest that large adult weight gain was a significant predictor of breast cancer in postmenopausal women not taking exogenous hormones.

A prospective study of serum insulin-like growth factor-I (IGF-I), IGF-II, IGF-binding protein-3 and breast cancer risk

The associations between serum concentrations of insulin-like growth factor-I (IGF-I), IGF-II and IGF-binding proteins (IGFBP)-3 and risk of breast cancer were investigated in a nested case–control study involving 117 cases (70 premenopausal and 47 postmenopausal at blood collection) and 350 matched controls within a cohort of women from the island of Guernsey, UK. Women using exogenous hormones at the time of blood collection were excluded. Premenopausal women in the top vs bottom third of serum IGF-I concentration had a nonsignificantly increased risk for breast cancer after adjustment for IGFBP-3 (odds ratio (OR) 1.71; 95% confidence interval (CI): 0.74–3.95; test for linear trend, P=0.21). Serum IGFBP-3 was associated with a reduction in risk in premenopausal women after adjustment for IGF-I (top third vs the bottom third: OR 0.49; 95% CI: 0.21–1.12, P for trend=0.07). Neither IGF-I nor IGFBP-3 was associated with risk in postmenopausal women and serum IGF-II concentration was not associated with risk in pre- or postmenopausal women. These data are compatible with the hypothesis that premenopausal women with a relatively high circulating concentration of IGF-I and low IGFBP-3 are at an increased risk of developing breast cancer.

A case--control study of selenium in nails and prostate cancer risk in British men

In view of the experimental evidence suggesting that the micronutrient selenium reduces prostate cancer risk, we investigated the association between the selenium level in fingernails, a measure of long-term selenium intake, and prostate cancer risk in a case–control study among 656 British men, conducted in 1989–1992. Nail clippings were taken at the time of recruitment and selenium concentration, measured using neutron activation techniques, was successfully assayed for 300 case–control pairs and varied six-fold among the controls (0.59 p.p.m.; interquartile range, 0.50–0.71 p.p.m.). Nail selenium concentration was not significantly associated with prostate cancer risk: men in the highest quartile of nail selenium had a slightly increased risk compared with men in the lowest quartile (OR 1.24, 95 CI, 0.73–2.10); for advanced prostate cancer, men in the highest quartile had a slightly reduced risk compared with men in the lowest quartile (OR 0.78, 95% CI, 0.27–2.25). These results suggest that selenium is not strongly associated with prostate cancer risk in British men.

Physical activity of subjects aged 50-64 years involved in the European Prospective Investigation into Cancer and Nutrition (EPIC)

OBJECTIVE

To describe physical activity of participants in the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN

A cross-sectional analysis of baseline data of a European prospective cohort study.

SUBJECTS

This analysis was restricted to participants in the age group 50-64 years, which was represented in all EPIC centres. It involved 236 386 participants from 25 centres in nine countries. In each EPIC centre, physical activity was assessed by standardised and validated questions. Frequency distribution of type of professional activity and participation in non-professional activities, and age-adjusted means, medians and percentiles of time dedicated to non-professional activities are presented for men and women from each centre.

RESULTS

Professional activity was most frequently classified as sedentary or standing in all centres. There was a wide variation regarding participation in different types of non-professional activities and time dedicated to these activities across EPIC centres. Over 80% of all EPIC participants engaged in walking, while less than 50% of the subjects participated in sport. Total time dedicated to recreational activities was highest among the Dutch participants and lowest among men from Malmö (Sweden) and women from Naples (Italy). In all centres, total time dedicated to recreational activity in the summer was higher than in the winter. Women from southern Europe spent the most time on housekeeping.

CONCLUSIONS

There is a considerable variation of physical activity across EPIC centres. This variation was especially evident for recreational activities in both men and women.

Soy product consumption in 10 European countries: the European Prospective Investigation into Cancer and Nutrition (EPIC) study

OBJECTIVE

The aim of this study was to describe the variation of soy product intake in 10 European countries by using a standardised reference dietary method. A subsidiary aim was to characterise the pattern of soy consumption among a sub-group of participants with a habitual health-conscious lifestyle (HHL), i.e. non-meat eaters who are fish eaters, vegetarians and vegans.

DESIGN

A 24-hour dietary recall interview (24-HDR) was conducted among a sample (5-12%) of all cohorts in the European Prospective Investigation into Cancer and Nutrition (EPIC). Study participants totalled 35 955 after exclusion of subjects younger than 35 or older than 74 years of age. Soy products were subdivided into seven sub-groups by similarity. Distribution of consumption and crude and adjusted means of intake were computed per soy product group across countries. Intake of soy products was also investigated among participants with an HHL.

RESULTS

In total, 195 men and 486 women reported consuming soy products in the 24-HDR interview. Although soy product intake was generally low across all countries, the highest intake level was observed in the UK, due to over-sampling of a large number of participants with an HHL. The most frequently consumed soy foods were dairy substitutes in the UK and France and beans and sprouts among mid-European countries. For both genders, the sub-group of soy dairy substitutes was consumed in the highest quantities (1.2 g day-1 for men; 1.9 g day-1 for women). Participants with an HHL differed substantially from others with regard to demographic, anthropometric and nutritional factors. They consumed higher quantities of almost all soy product groups.

CONCLUSIONS

Consumption of soy products is low in centres in Western Europe. Soy dairy substitutes are most frequently consumed. Participants with an HHL form a distinct sub-group with higher consumptions of fruit, vegetables, legumes, cereals and soy products compared with the other participants.

Soya intake and plasma concentrations of daidzein and genistein: validity of dietary assessment among eighty British women (Oxford arm of the European Prospective Investigation into Cancer and Nutrition)

Soya products contain high levels of the isoflavones genistein and daidzein, and their glucosides, and may lower the risk of cardiovascular disease, osteoporosis and cancer. The present cross-sectional study investigated plasma concentrations of daidzein and genistein and their correlations with dietary soya consumption in four groups of twenty premenopausal British women. The women were selected from the Oxford arm of the European Prospective Investigation into Cancer and Nutrition using data from food-frequency questionnaires (FFQ) to guarantee a wide variation in soya consumption, and to investigate the utility of the question related to soya milk consumption compared with the utility of the question related to other soya foods. Dietary intakes of isoflavones were additionally assessed by 7 d food diaries. Plasma concentrations of daidzein and genistein were measured by time-resolved fluoroimmunoassay. Geometric mean plasma concentrations (nmol/l) were for the four groups, which were based on increasing soya intake, 4.9, 8.4, 39.2 and 132 for daidzein and 14.3, 16.5, 119 and 378 for genistein. The Spearman correlation coefficients for plasma isoflavone concentrations with estimated dietary intakes were between 0.66 and 0.80 for the diary-based estimates and between 0.24 and 0.74 for the FFQ-based estimates. The correlations for soya milk intakes were clearly higher than the correlations for intakes of other soya foods. We conclude that both the food diary and the FFQ estimate dietary soya isoflavone intakes sufficiently well to use them in epidemiological studies, and that plasma concentrations of daidzein and genistein in Western women who consumed soya products as a part of their regular diet were close to those in Asian populations.

The association between polymorphisms in the CYP17 and 5alpha-reductase (SRD5A2) genes and serum androgen concentrations in men

Prospective studies suggest that prostate cancer risk may be increased in association with high serum concentrations of free testosterone and androstanediol glucuronide (A-diol-g). Polymorphisms have been identified in the 17-hydroxylase cytochrome P450 gene (CYP17) and the steroid 5alpha-reductase type II gene (SRD5A2), two genes that are involved in the biosynthesis and metabolism of androgens in men. The CYP17 MspA1 I polymorphism has been associated with increased prostate cancer risk, and the SRD5A2 V89L polymorphism has been associated with low A-diol-g in Asian men, a serum marker of 5alpha-reductase activity. The purpose of this study was to investigate the association between these two polymorphisms and serum sex hormone concentrations in 621 British men. In particular, we wanted to test the hypotheses that the A2 allele in the CYP17 gene is associated with increased serum testosterone concentrations, and the L allele in the SRD5A2 gene is associated with reduced A-diol-g concentrations. Mean hormone concentrations were evaluated in each genotype and adjusted for age and other relevant factors. We found no evidence that the CYP17 MspA1 I polymorphism was associated with higher testosterone levels. The L/L genotype of the SRD5A2 V89L polymorphism was associated with a 10% lower A-diol-g concentration, but this was not significant at the 5% level. However, the L/L genotype of the V89L polymorphism was associated with significantly lower concentrations of testosterone and free testosterone (by 12% and 16%, respectively) and an 8% higher sex hormone-binding globulin concentration. These results suggest that the CYP17 MspA1 I polymorphism is not associated with testosterone concentrations and that the SRD5A2 V89L polymorphism is not a strong determinant of A-diol-g concentration in Caucasian men.

Energy balance and cancer: the role of sex hormones

Energy balance can affect the risk for hormone-related cancers by altering sex hormone levels. Energy intake and expenditure are difficult to measure in epidemiological studies, but a chronic excess of intake relative to expenditure leads to a high BMI, which can be accurately measured. In premenopausal women obesity has little effect on the serum concentration of oestradiol, but causes an increase in the frequency of anovular menstrual cycles and thus a reduction in progesterone levels; these changes lead to a large increase in the risk for endometrial cancer. but little change, or a small decrease, in the risk for breast cancer. In post-menopausal women oestradiol levels are not regulated by negative feedback, and obesity causes an increase in the serum concentration of bioavailable oestradiol; this factor causes increases in the risk for both endometrial cancer and breast cancer. The development of ovarian cancer appears to be related more strongly to the frequency of ovulation than to direct effects of circulating levels of sex hormones, and BMI is not clearly associated with the risk for ovarian cancer. In men, increasing BMI has little effect on bioavailable androgen levels, and any effect of obesity on prostate cancer risk is small.

Soy milk intake in relation to serum sex hormone levels in British men

Soy beans contain high levels of the isoflavones genistein and daidzein and their glycosides and have been implicated in the prevention of prostate cancer, possibly via their effects on sex hormone metabolism. The aim of this study was to assess the relation between dietary soy intake and sex hormone levels in a cross-sectional analysis of 696 men with a wide range of soy intakes. Soy milk intake was measured using a validated semiquantitative food frequency questionnaire, and serum hormone concentrations were measured by immunoassay. Multiple regression was used to investigate the association between soy milk intake, an index of isoflavone intake, and hormone levels after adjustment for pertinent confounders. Soy milk intake was not associated with serum concentrations of testosterone, free testosterone, androstanediol glucuronide, sex hormone-binding globulin, or luteinizing hormone. These results suggest that soy milk intake, as a marker of isoflavone intake, is not associated with serum sex hormone concentrations among free-living Western men.

Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men

Mean serum insulin-like growth factor-I was 9% lower in 233 vegan men than in 226 meat-eaters and 237 vegetarians (P = 0.002). Vegans had higher testosterone levels than vegetarians and meat-eaters, but this was offset by higher sex hormone binding globulin, and there were no differences between diet groups in free testosterone, androstanediol glucuronide or luteinizing hormone.

Ecological factors impacting provider attitudes towards human service delivery reform

Although reform efforts are substantially altering the structural operations and guiding ideological framework of the human service delivery system, little empirical work has been done to systematically examine these transformations. This study examines providers' attitudes regarding two reform elements that are being widely implemented: an increased emphasis on interagency collaboration and a shift from a medical model service delivery philosophy, that focuses on client deficits, to one that emphasizes consumer strengths. Through survey data collected from 186 providers from 32 human service agencies in one county, the relationship between providers' perceptions of contextual support for human service delivery reform and providers' attitudes towards these initiatives is explored. The findings from this study support the importance of attending to the ecology in which we initiate system reform efforts. For both reform elements, working within contexts that are perceived as providing ideological and functional support for change was associated with positive provider attitudes towards those changes. Staffs' perceptions of the external environment played the most critical role in shaping staff attitudes. Interestingly, unique aspects of providers' work environments were related to positive attitudes towards the two different reforms. The implications of these findings for the success of human service delivery reform are discussed.

The role of hydrophobic side chains as determinants of antibacterial activity of semisynthetic glycopeptide antibiotics

Vancomycin, LY264826 and four N-substituted derivatives of LY264826 were examined for dimerization, binding to D-alanyl-D-alanine- and D-alanyl-D-lactate-containing cell wall ligands, and binding to bacterial membrane vesicles. The six glycopeptide antibiotics represent a 360-fold range in antibacterial activities against Micrococcus luteus (MIC = 0.00072-0.26 microM) with the N-substituted compounds having the lowest MICs. Vancomycin, LY264826 and the four N-substituted derivatives shared nearly identical binding affinities for N,N'-diacetyl-L-lysyl-D-alanyl-D-alanine (Kb = 1.5 x 10(5) approximately 5.9 x 10(5) M-1). Affinities for binding N,N'-diacetyl-L-lysyl-D-alanyl-D-lactate were lower but also represented a narrow range (Kb = 0.24 x 10(3) approximately 1.6 x 10(3) M-1). In contrast to ligand binding, the relative capacity of the six compounds to dimerize differed by four orders of magnitude (Kdim = 4.9 x 10(1)-1.2 x 10(6) M-1). The N-substituted derivatives had the highest Kdim values, required the greatest molar excess of exogenous cell wall ligand to suppress inhibition, and demonstrated a propensity to bind to bacterial membrane vesicles. The derivatives with the most lipophilic side chains were the most highly bound to vesicles. The findings suggest that the enhanced antibacterial activities of N-substituted derivatives of LY264826 derive from the nature of the hydrophobic side chain which can have a marked effect on dimerization and membrane binding.

Use of capillary electrophoresis to measure dimerization of glycopeptide antibiotics

Capillary electrophoretic methods were used to examine dimerization and estimate dimerization constants (Kdim) for the glycopeptide antibiotics vancomycin, ristocetin A, and LY264826 (A82846B). The Kdim for LY264826 was 60- and 200-fold higher than the Kdim for ristocetin A and vancomycin, respectively. Dimerization of vancomycin measured in the presence of the cell wall analog N, N'-diacetyl-L-Lys-D-Ala-D-Ala was enhanced 200-fold; however, dimerization of ristocetin A was antagonized by the presence of N, N'-diacetyl-L-Lys-D-Ala-D-Ala. The relative differences in Kdim determined by capillary electrophoresis in general follow the same trend as those observed using nuclear magnetic resonance spectroscopy and sedimentation equilibrium.

Parkinson's disease: an investigation of exercise capacity, respiratory function, and gait

OBJECTIVE

To evaluate the exercise capacity of subjects with mild to moderate Parkinson's disease and determine whether abnormalities in respiratory function and gait affect exercise capacity.

DESIGN

Descriptive. Subjects were categorized according to exercise history, disease severity, and presence/absence of upper airway obstruction.

SUBJECTS AND SETTING

Sixteen volunteers with mild to moderate idiopathic Parkinson's disease attended a university research laboratory.

MAIN OUTCOME MEASURES

Subjects performed a maximum exercise test on a cycle ergometer, together with respiratory function tests and a walking test. Peak values for oxygen consumption and work rate were recorded for the maximum exercise test. Measures of respiratory function included spirometry, flow-volume loops, lung volumes, and mouth pressures. Velocity, stride length, and cadence were measured for preferred and fast speeds of walking. The values obtained on each of these tests were compared with published predicted age- and gender-matched normal values.

RESULTS

Peak oxygen consumptions and peak work loads achieved by subjects with Parkinson's disease were not significantly different from normal values, despite evidence of respiratory and gait abnormalities typical of Parkinson's disease. Exercise category was significantly correlated with percent predicted VO2peak (r = .64, p < .01), with sedentary subjects producing lower scores than exercising subjects. There was no significant correlation between disease severity and percent predicted VO2peak.

CONCLUSION

Despite their neurological deficit, individuals with mild to moderate Parkinson's disease have the potential to maintain normal exercise capacity with regular aerobic exercise.

Molecular interactions of a semisynthetic glycopeptide antibiotic with D-alanyl-D-alanine and D-alanyl-D-lactate residues

LY191145 is an N-alkylated glycopeptide antibiotic (the p-chlorobenzyl derivative of LY264826) with activity against vancomycin-susceptible and -resistant bacteria. Similar to vancomycin, LY191145 inhibited polymerization of peptidoglycan when muramyl pentapeptide served as a substrate but not when muramyl tetrapeptide was used, signifying a substrate-dependent mechanism of inhibition. Examination of ligand binding affinities for LY191145 and the effects of this agent on R39 D,D-carboxypeptidase action showed that, similar to vancomycin, LY191145 had an 800-fold greater affinity for N,N'-diacetyl-L-Lys-D-Ala-D-Ala than for N,N'-diacetyl-L-Lys-D-Ala-D-Lac. The antibacterial activity of LY191145 was antagonized by N,N'-diacetyl-L-Lys-D-Ala-D-Ala, but the molar excess required for complete suppression exceeded that needed to suppress inhibition by vancomycin. LY191145 is strongly dimerized and the p-chlorobenzyl side chain facilitates interactions with bacterial membranes. These findings are consistent with a mechanism of inhibition where interactions between antibiotic and D-Ala-D-Ala or D-Ala-D-Lac residues depend on intramolecular effects occurring at the subcellular target site.

Inhibition of peptidoglycan biosynthesis in vancomycin-susceptible and -resistant bacteria by a semisynthetic glycopeptide antibiotic

LY191145 is a p-chlorobenzyl derivative of LY264826 (A82846B) with activity against both vancomycin-susceptible and -resistant enterococci. Incorporation of L-[14C]lysine into peptidoglycan of intact vancomycin-susceptible and -resistant Enterococcus faecium was inhibited by LY191145 (50% inhibitory concentrations of 1 and 5 microgram/ml, respectively). Inhibition was accompanied by accumulation of UDP-muramyl-peptide precursors in the cytoplasm. This agent inhibited late-stage steps in peptidoglycan biosynthesis in permeabilized E. faecium when either the UDP-muramyl-pentapeptide precursor from vancomycin-susceptible E. faecium or the UDP-muramyl-pentadepsipeptide precursor from vancomycin-resistant E. faecium was used as a substrate. Inhibition of late-stage steps led to accumulation of an N-acetyl-[14C]glucosamine-labeled lipid intermediate indicative of inhibition of the transglycosylation step. Inhibition of peptidoglycan polymerization without affecting cross-linking in a particulate membrane-plus-wall-fragment assay from Aerococcus viridans was consistent with this explanation. The fact that inhibition of peptidoglycan biosynthesis by LY191145 was not readily antagonized by an excess of free acyl-D-alanyl-D-alanine or acyl-D-alanyl-D-lactate ligands indicates that the manner in which this compound inhibits transglycosylation may not be identical to that of vancomycin.

Knockout of the two ldh genes has a major impact on peptidoglycan precursor synthesis in Lactobacillus plantarum

Most bacteria synthesize muramyl-pentapeptide peptidoglycan precursors ending with a D-alanyl residue (e.g., UDP-N-acetylmuramyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala). However, it was recently demonstrated that other types of precursors, notably D-lactate-ending molecules, could be synthesized by several lactic acid bacteria. This particular feature leads to vancomycin resistance. Vancomycin is a glycopeptide antibiotic that blocks cell wall synthesis by the formation of a complex with the extremity of peptidoglycan precursors. Substitution of the terminal D-alanine by D-lactate reduces the affinity of the antibiotic for its target. Lactobacillus plantarum is a lactic acid bacterium naturally resistant to vancomycin. It converts most of the glycolytic pyruvate to L- and D-lactate by using stereospecific enzymes designated L- and D-lactate dehydrogenases, respectively. In the present study, we show that L. plantarum actually synthesizes D-lactate-ending peptidoglycan precursors. We also report the construction of a strain which is deficient for both D- and L-lactate dehydrogenase activities and which produces only trace amounts of D- and L-lactate. As a consequence, the peptidoglycan synthesis pathway is drastically affected. The wild-type precursor is still present, but a new type of D-alanine-ending precursor is also synthesized in large quantities, which results in a highly enhanced sensitivity to vancomycin.

Induction of vancomycin resistance in Enterococcus faecium by non-glycopeptide antibiotics

Bacitracin and other antibiotics that inhibit late stages in peptidoglycan biosynthesis induce vancomycin resistance in a high-level, inducibly vancomycin-resistant strain of Enterococcus faecium. Exposure to bacitracin led to synthesis of the lactate-containing UDP-MurNAc-pentadepsipeptide precursor required for vancomycin resistance. These findings indicate that inhibition of peptidoglycan biosynthesis can lead to induction of vancomycin resistance and raise the possibility that multiple signals may serve to induce resistance.

Inhibitors of two-component signal transduction systems: inhibition of alginate gene activation in Pseudomonas aeruginosa

Pseudomonas aeruginosa strains infecting cystic fibrosis patients often produce copious amounts of the exopolysaccharide alginate. Expression of alginate genes in P. aeruginosa is regulated by several proteins including members of the two-component bacterial signal transduction systems. Two of these regulatory proteins are AlgR1, the DNA-binding response regulator that transcriptionally activates alginate gene expression, and AlgR2, the kinase that modifies AlgR1 via phosphorylation to enhance its activity. In this paper, we report the identification of compounds that inhibit alginate gene expression by inhibiting (i) the phosphorylation/dephosphorylation of AlgR2 and (ii) the DNA-binding activity of AlgR1. Compounds with these activities may have potential as components of therapy for eliminating P. aeruginosa infection from the cystic fibrosis lung. In addition, we describe the effect of these compounds on the autophosphorylation activity of other known two-component kinases and show the ability of one compound to significantly inhibit the kinase activities of CheA, NRII, and KinA.

Biosynthesis of modified peptidoglycan precursors by vancomycin-resistant Enterococcus faecium

In the presence of bacitracin, vancomycin-resistant Enterococcus faecium (vanA phenotype) accumulate UDP-N-acetylmuramyl(UDP-Mur-NAc)-tetrapeptide and a UDP-MurNAc-depsipentapeptide containing lactate substituted for the carboxy-terminal-D-alanine residue. In an in vitro peptidoglycan polymerization assay, the modified precursors function and confer resistance to vancomycin.

Inhibition of membrane potential-dependent amino acid transport by daptomycin

Daptomycin inhibits the formation of UDP-N-acetylmuramyl-pentapeptide in Bacillus megaterium by inhibiting active transport of amino acids incorporated into the pentapeptide. The ability of daptomycin to inhibit active transport and peptidoglycan formation may be due to its ability to disrupt the transmembrane electrochemical gradient.