The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults

The gain-of-function mutation in the TALK-1 K+ channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion. The KCNK16 gene encoding TALK-1 is the most abundant and β-cell-restricted K+ channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the CD-1 (ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K+ currents resulting in blunted glucose-stimulated Ca2+ entry and loss of glucose-induced Ca2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impairs glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet insulin secretion during development. These data suggest that TALK-1 is an islet-restricted target for the treatment for diabetes.

Endocrine islet β-cell subtypes with differential function are derived from biochemically distinct embryonic endocrine islet progenitors that are regulated by maternal nutrients

Endocrine islet b cells comprise heterogenous cell subsets. Yet when/how these subsets are produced and how stable they are remain unknown. Addressing these questions is important for preventing/curing diabetes, because lower numbers of b cells with better secretory function is a high risk of this disease. Using combinatorial cell lineage tracing, scRNA-seq, and DNA methylation analysis, we show here that embryonic islet progenitors with distinct gene expression and DNA methylation produce b-cell subtypes of different function and viability in adult mice. The subtype with better function is enriched for genes involved in vesicular production/trafficking, stress response, and Ca2+-secretion coupling, which further correspond to differential DNA methylation in putative enhancers of these genes. Maternal overnutrition, a major diabetes risk factor, reduces the proportion of endocrine progenitors of the b-cell subtype with better-function via deregulating DNA methyl transferase 3a. Intriguingly, the gene signature that defines mouse b-cell subtypes can reliably divide human cells into two sub-populations while the proportion of b cells with better-function is reduced in diabetic donors. The implication of these results is that modulating DNA methylation in islet progenitors using maternal food supplements can be explored to improve b-cell function in the prevention and therapy of diabetes.

The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults

The gain-of-function mutation in the TALK-1 K + channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion (GSIS). The KCNK16 gene encoding TALK-1, is the most abundant and β-cell-restricted K + channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the mixed C57BL/6J:CD-1(ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K + currents resulting in blunted glucose-stimulated Ca 2+ entry and loss of glucose-induced Ca 2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impaired glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet hormone secretion during development. These data strongly suggest that TALK-1 is an islet-restricted target for the treatment of diabetes.

Differential regulation of alternate promoter regions in Sox17 during endodermal and vascular endothelial development

Sox17 gene expression is essential for both endothelial and endodermal cell differentiation. To better understand the genetic basis for the expression of multiple Sox17 mRNA forms, we identified and performed CRISPR/Cas9 mutagenesis of two evolutionarily conserved promoter regions (CRs). The deletion of the upstream and endothelial cell-specific CR1 caused only a modest increase in lympho-vasculogenesis likely via reduced Notch signaling downstream of SOX17. In contrast, the deletion of the downstream CR2 region, which functions in both endothelial and endodermal cells, impairs both vascular and endodermal development causing death by embryonic day 12.5. Analyses of 3D chromatin looping, transcription factor binding, histone modification, and chromatin accessibility data at the Sox17 locus and surrounding region further support differential regulation of the two promoters during the development.

TRAF6 Mediates Basal Activation of NF-κB Necessary for Hematopoietic Stem Cell Homeostasis

Basal nuclear factor κB (NF-κB) activation is required for hematopoietic stem cell (HSC) homeostasis in the absence of inflammation; however, the upstream mediators of basal NF-κB signaling are less well understood. Here, we describe TRAF6 as an essential regulator of HSC homeostasis through basal activation of NF-κB. Hematopoietic-specific deletion of Traf6 resulted in impaired HSC self-renewal and fitness. Gene expression, RNA splicing, and molecular analyses of Traf6-deficient hematopoietic stem/progenitor cells (HSPCs) revealed changes in adaptive immune signaling, innate immune signaling, and NF-κB signaling, indicating that signaling via TRAF6 in the absence of cytokine stimulation and/or infection is required for HSC function. In addition, we established that loss of IκB kinase beta (IKKβ)-mediated NF-κB activation is responsible for the major hematopoietic defects observed in Traf6-deficient HSPC as deletion of IKKβ similarly resulted in impaired HSC self-renewal and fitness. Taken together, TRAF6 is required for HSC homeostasis by maintaining a minimal threshold level of IKKβ/NF-κB signaling.

Implementation of the North Carolina HIV Bridge Counseling Program to Facilitate Linkage and Reengagement in Care for Individuals Infected with HIV/AIDS

BACKGROUND Statewide interventions are critical to meeting the goals of the National HIV/AIDS Strategy in this country. In 2012, the North Carolina Division of Public Health developed the North Carolina State Bridge Counselor program to improve linkage to and reengagement in care for newly diagnosed persons and persons living with HIV who were out-of-care.METHODS We reviewed the planning process for the North Carolina State Bridge Counselor program, which involved a review of existing strengths-based counseling models for persons living with HIV, implementation of these models, and communication strategies with other providers. State bridge counselor responsibilities were delineated from the role of disease intervention specialists while retaining the fieldwork capability of disease intervention specialists to conduct outreach and provide services for persons living with HIV throughout the state.RESULTS Program implementation required extensive planning with stakeholders, incorporation of strengths-based counseling models, development of performance standards, and utilization of CAREWare, an HIV care software program to document referrals and data-sharing between state bridge counselors and clinics. By the end of 2014, state bridge counselor services were provided to approximately 60 of the 400 persons living with HIV (15%) who are diagnosed each quarter in North Carolina, with increasing utilization of the program.LIMITATIONS We assessed the development of this intervention specific to the North Carolina Division of Public Health, which may limit its generalizability. However, the State Bridge Counselor program was implemented in both urban and rural areas throughout the state, which increases its applicability to different public health programs throughout the country.CONCLUSION We demonstrated that a statewide State Bridge Counselor program for linkage and reengagement activities can be implemented by leveraging existing infrastructures, electronic medical records, HIV care networks, and fieldwork activities.

RHOA GTPase Controls YAP-Mediated EREG Signaling in Small Intestinal Stem Cell Maintenance

RHOA, a founding member of the Rho GTPase family, is critical for actomyosin dynamics, polarity, and morphogenesis in response to developmental cues, mechanical stress, and inflammation. In murine small intestinal epithelium, inducible RHOA deletion causes a loss of epithelial polarity, with disrupted villi and crypt organization. In the intestinal crypts, RHOA deficiency results in reduced cell proliferation, increased apoptosis, and a loss of intestinal stem cells (ISCs) that mimic effects of radiation damage. Mechanistically, RHOA loss reduces YAP signaling of the Hippo pathway and affects YAP effector epiregulin (EREG) expression in the crypts. Expression of an active YAP (S112A) mutant rescues ISC marker expression, ISC regeneration, and ISC-associated Wnt signaling, but not defective epithelial polarity, in RhoA knockout mice, implicating YAP in RHOA-regulated ISC function. EREG treatment or active β-catenin Catnb^lox(ex3) mutant expression rescues the RhoA KO ISC phenotypes. Thus, RHOA controls YAP-EREG signaling to regulate intestinal homeostasis and ISC regeneration.

Distinct roles for the mTOR pathway in postnatal morphogenesis, maturation and function of pancreatic islets

While much is known about the molecular pathways that regulate embryonic development and adult homeostasis of the endocrine pancreas, little is known about what regulates early postnatal development and maturation of islets. Given that birth marks the first exposure to enteral nutrition, we investigated how nutrient-regulated signaling pathways influence postnatal islet development in mice. We performed loss-of-function studies of mechanistic target of rapamycin (mTOR), a highly conserved kinase within a nutrient-sensing pathway known to regulate cellular growth, morphogenesis and metabolism. Deletion of Mtor in pancreatic endocrine cells had no significant effect on their embryonic development. However, within the first 2 weeks after birth, mTOR-deficient islets became dysmorphic, β-cell maturation and function were impaired, and animals lost islet mass. Moreover, we discovered that these distinct functions of mTOR are mediated by separate downstream branches of the pathway, in that mTORC1 (with adaptor protein Raptor) is the main complex mediating the maturation and function of islets, whereas mTORC2 (with adaptor protein Rictor) impacts islet mass and architecture. Taken together, these findings suggest that nutrient sensing may be an essential trigger for postnatal β-cell maturation and islet development.

The association between socio-demographic marginalization and plasma glucose levels at diagnosis of gestational diabetes

AIMS

We examined the association between socio-demographic marginalization and plasma glucose levels at diagnosis of gestational diabetes in a multi-ethnic and socio-economically diverse patient group.

METHODS

Medical charts at a Toronto gestational diabetes clinic were reviewed for women with a recorded pregnancy between 1 March 2006 and 26 April 2011. One-hour 50-g glucose challenge test values and postal code data were abstracted. Postal codes were merged with 2006 Canadian census data to compute neighbourhood-level ethnic concentration (% recent immigrants, % visible minorities) and material deprivation (% low education, % low income, single-parent households). We compared women in the highest neighbourhood quintiles for both ethnic concentration and material deprivation with all other women to explore an association between marginalization and diagnostic glucose levels. Multivariate regression models of glucose challenge test values and insulin prescription were adjusted for age, prior gestational diabetes, parity and diabetes family history.

RESULTS

Among 531 patients with complete glucose challenge test data (mean 11.94 mmol/l, sd 1.83), those in the most marginalized neighbourhoods had 0.43 mmol/l higher glucose challenge test values (95% CI 0.08-0.78) compared with the rest of the study population. Other factors associated with higher glucose challenge test values were prior gestational diabetes (0.59 mmol/l increment, 95% CI 0.19-0.99) and diabetes family history (0.32 mmol/l increment, 95% CI -0.01 to 0.66). Each additional 1 mmol/l glucose challenge test result was associated with an increased likelihood of being prescribed insulin (odds ratio 1.33, 95% CI 1.17-1.51).

CONCLUSIONS

Women living in the most materially deprived and ethnically concentrated neighbourhoods have higher glucose levels at diagnosis of gestational diabetes. They may need close monitoring for timely initiation of insulin.

Cdc42 coordinates proliferation, polarity, migration, and differentiation of small intestinal epithelial cells in mice

BACKGROUND & AIMS

Cdc42 is a Rho GTPase that regulates diverse cellular functions, including proliferation, differentiation, migration, and polarity. In the intestinal epithelium, a balance among these events maintains homeostasis. We used genetic techniques to investigate the role of Cdc42 in intestinal homeostasis and its mechanisms.

METHODS

We disrupted Cdc42 specifically in intestinal epithelial cells by creating Cdc42flox/flox-villin-Cre+ and Cdc42flox/flox-Rosa26-CreER+ mice. We collected intestinal and other tissues, and analyzed their cellular, molecular, morphologic, and physiologic features, compared with the respective heterozygous mice.

RESULTS

In all mutant mice studied, the intestinal epithelium had gross hyperplasia, crypt enlargement, microvilli inclusion, and abnormal epithelial permeability. Cdc42 deficiency resulted in defective Paneth cell differentiation and localization without affecting the differentiation of other cell lineages. In mutant intestinal crypts, proliferating stem and progenitor cells increased, compared with control mice, resulting in increased crypt depth. Cdc42 deficiency increased migration of stem and progenitor cells along the villi, caused a mild defect in the apical junction orientation, and impaired intestinal epithelium polarity, which can contribute to the observed defective intestinal permeability. The intestinal epithelium of the Cdc42flox/flox-villin-Cre+ and Cdc42flox/flox-Rosa26-CreER+ mice appeared similar to that of patients with microvillus inclusion disease. In the digestive track, loss of Cdc42 also resulted in crypt hyperplasia in the colon, but not the stomach.

CONCLUSIONS

Cdc42 regulates proliferation, polarity, migration, and differentiation of intestinal epithelial cells in mice and maintains intestine epithelial barrier and homeostasis. Defects in Cdc42 signaling could be associated with microvillus inclusion disease.

Dietary glycemic index, glycemic load, insulin index, fiber and whole-grain intake in relation to risk of prostate cancer

OBJECTIVE

Insulin may play a role in prostate cancer tumorigenesis. Postprandial blood glucose and insulin responses of foods depend importantly on the carbohydrate quality and quantity, represented by glycemic index (GI), glycemic load (GL), fiber and whole-grain content, but are also influenced by intake of protein and other characteristics. The recently developed insulin index (II) quantifies the postprandial insulin secretion, also taking into account these additional characteristics.

METHODS

We investigated the association between dietary GI, GL, II, fiber, and whole grains and risk of total prostate cancer (n = 5,112) and subgroups of prostate cancer as defined by stage or grade in 49,934 male participants of the Health Professionals Follow-up Study. Multivariate adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) were estimated using Cox proportional hazards regression.

RESULTS

Dietary GI, GL, II, or fiber was not associated with risk of total or subgroups of prostate cancer. We observed a positive association between dietary intake of whole grains and total prostate cancer (HR highest versus lowest quintile 1.13, 95% CI 1.03-1.24), which was attenuated after restriction to PSA-screened participants (HR 1.03, 95% CI 0.91-1.17).

CONCLUSIONS

These results suggest that long-term exposure to a diet with a high insulin response does not affect prostate cancer incidence.

Electrode displacement strain imaging of thermally-ablated liver tissue in an in vivo animal model

PURPOSE

Percutaneous thermal ablation is increasingly being used to destroy hepatic tumors in situ. The success of ablative techniques is highly dependent on adequate ablation zone monitoring, and ultrasound-based strain imaging could become a convenient and cost-effective means to delineate ablation zone boundaries. This study investigates in vivo electrode displacement-based strain imaging for monitoring hepatic ablation procedures that are difficult to perform with conventional elastography.

METHODS

a In our method, minute displacements (less than a millimeter) are applied to the unconstrained end of the ablation electrode, resulting in localized tissue deformation within the ablation zone that provides the mechanical stimuli required for strain imaging. This article presents electrode displacement strain images of radiofrequency ablation zones created in porcine liver in vivo (n = 13).

RESULTS

Cross-sectional area measurements from strain images of these ablation zones were obtained using manual and automated segmentation. Area measurements from strain images were highly correlated with areas measured on histopathology images, quantitated using linear regression (R = 0.894, P < 0.001 and R = 0.828, P < 0.001, respectively).

CONCLUSIONS

This study further demonstrates that electrode displacement elastography is capable of providing high-contrast images using widely available commercial ultrasound systems which may potentially be used to assess the extent of thermal ablation zones.

A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women

BACKGROUND

Little is known about the effects of the amount and type of carbohydrates on risk of coronary heart disease (CHD).

OBJECTIVE

The objective of this study was to prospectively evaluate the relations of the amount and type of carbohydrates with risk of CHD.

DESIGN

A cohort of 75521 women aged 38-63 y with no previous diagnosis of diabetes mellitus, myocardial infarction, angina, stroke, or other cardiovascular diseases in 1984 was followed for 10 y. Each participant's dietary glycemic load was calculated as a function of glycemic index, carbohydrate content, and frequency of intake of individual foods reported on a validated food-frequency questionnaire at baseline. All dietary variables were updated in 1986 and 1990.

RESULTS

During 10 y of follow-up (729472 person-years), 761 cases of CHD (208 fatal and 553 nonfatal) were documented. Dietary glycemic load was directly associated with risk of CHD after adjustment for age, smoking status, total energy intake, and other coronary disease risk factors. The relative risks from the lowest to highest quintiles of glycemic load were 1.00, 1.01, 1. 25, 1.51, and 1.98 (95% CI: 1.41, 2.77 for the highest quintile; P for trend < 0.0001). Carbohydrate classified by glycemic index, as opposed to its traditional classification as either simple or complex, was a better predictor of CHD risk. The association between dietary glycemic load and CHD risk was most evident among women with body weights above average ¿ie, body mass index (in kg/m(2)) >/= 23.

CONCLUSION

These epidemiologic data suggest that a high dietary glycemic load from refined carbohydrates increases the risk of CHD, independent of known coronary disease risk factors.

Reproducibility and validity of dietary patterns assessed with a food-frequency questionnaire

BACKGROUND

Recently, the analysis of dietary patterns has emerged as a possible approach to examining diet-disease relations.

OBJECTIVE

We examined the reproducibility and validity of dietary patterns defined by factor analysis using dietary data collected with a food-frequency questionnaire (FFQ).

DESIGN

We enrolled a subsample of men (n = 127) from the Health Professionals Follow-up Study in a diet-validation study in 1986. A 131-item FFQ was administered twice, 1 y apart, and two 1-wk diet records and blood samples were collected during this 1-y interval.

RESULTS

Using factor analysis, we identified 2 major eating patterns, which were qualitatively similar across the 2 FFQs and the diet records. The first factor, the prudent dietary pattern, was characterized by a high intake of vegetables, fruit, legumes, whole grains, and fish and other seafood, whereas the second factor, the Western pattern, was characterized by a high intake of processed meat, red meat, butter, high-fat dairy products, eggs, and refined grains. The reliability correlations for the factor scores between the 2 FFQs were 0.70 for the prudent pattern and 0.67 for the Western pattern. The correlations (corrected for week-to-week variation in diet records) between the 2 FFQs and diet records ranged from 0.45 to 0.74 for the 2 patterns. In addition, the correlations between the factor scores and nutrient intakes and plasma concentrations of biomarkers were in the expected direction.

CONCLUSIONS

These data indicate reasonable reproducibility and validity of the major dietary patterns defined by factor analysis with data from an FFQ.

Structure-activity relationship study of steroidal and nonsteroidal inhibitors of the enzyme estrone sulfatase

We report the initial results of a series of molecular modelling studies to investigate the structural properties of non-steroidal inhibitors required for inhibitory activity against the enzyme estrone sulfatase (ES) [the enzyme responsible for the conversion of nonactive (sulfated) estrone to the active (nonsulfated) estrone]. From the results of the present study, we conclude that the C(17) polar group may not be necessary for inhibitory activity and that the only requirement appears to be the mimicking of the steroid C(3) sulfonate group. To test our hypotheses, we have designed novel straight chain inhibitors based upon alkyl alcohols, which upon evaluation, have been shown to possess inhibitory activity (e.g., an inhibitor based upon trichloroethanol has been shown to possess 46% inhibition at 0.76mM).

A helical coat protein recognition domain of the bacteriophage P22 scaffolding protein

The scaffolding protein of bacteriophage P22 directs the assembly of an icosahedral procapsid, a metastable shell that is the precursor for DNA packaging. The full-length protein has been shown previously to exist in a monomer-dimer-tetramer equilibrium of elongated and predominantly alpha-helical molecules. Two deletion-mutant fragments of the scaffolding protein, comprising amino acid residues 141 to 303 and 141 to 292, respectively, have been constructed, overexpressed in Escherichia coli, and purified. Removal of residues 1 to 140 yields a protein that is assembly-active both in vitro and in vivo, while the removal of the C-terminal 11 residues (293 to 303) leads to complete loss of scaffolding activity. Sedimentation analysis reveals that both scaffolding fragments exist in a monomer-dimer equilibrium governed by apparent dissociation constants Kd(141-303)=640 microM and Kd(141-292)=880 microM. Tetramer formation is not observed for either fragment; thus, the tetramerization domain of the scaffolding subunit resides in the N-terminal portion of the polypeptide chain. Examination of both fragments by circular dichroism, Raman and NMR spectroscopies indicates a highly alpha-helical fold in each case. Nonetheless, pronounced differences are observed between spectral signatures of the two fragments. Notably, Raman spectra of fragments 141-292 and 141-303 indicate that elimination of residues 293 to 303 results in unfolding of an alpha-helical coat protein "recognition" domain encompassing about 20 to 30 residues. The thermostability of fragment 141-303, monitored over a wide concentration range by circular dichroism and Raman spectroscopy, indicates a broad denaturation transition for the monomeric (low concentration) form, while more cooperative unfolding is observed for the dimeric (high concentration) form. A lesser increase in cooperativity upon dimerization is obtained for fragment 141-292. Additionally, the C-terminal recognition domain constitutes the most stable and cooperative unit in the 141-303 fragment. Measurement of hydrogen-isotope exchange kinetics in scaffolding fragments by time-resolved Raman spectroscopy shows that the C terminus is the only protected segment of the polypeptide chain. On the basis of the measured hydrodynamic and spectroscopic properties, a domain structure is proposed for the scaffolding subunit. The roles of these domains in P22 procapsid assembly are discussed.

A prospective study of dietary fiber types and symptomatic diverticular disease in men

To examine prospectively dietary fiber calculated from food composition values based on analytic techniques and specific dietary fiber types in relation to risk of diverticular disease, we analyzed data from a prospective cohort of 43,881 U.S. male health professionals 40-75 y of age at base line; subjects were free of diagnosed diverticular disease, colon or rectal polyps, ulcerative colitis and cancer. The insoluble component of fiber was inversely associated with risk of diverticular disease relative risk (RR) = 0. 63, 95% confidence interval (CI), 0.44-0.91, P for trend = 0.02, and this association was particularly strong for cellulose (RR = 0.52, 95% CI, 0.36-0.75, P for trend = 0.002). The association between diverticular disease and total dietary fiber intake calculated from the AOACstandards method was not appreciably different from results using the Southgate or Englyst method [for AOAC method, RR = 0.60, 95% CI, 0.41-0.87; for Southgate method, RR = 0.61, 95% CI, 0.42-0. 88; for Englyst method, RR = 0.60, 95% CI, 0.42-0.87, for the highest quintiles]. Our findings provide evidence for the hypothesis that a diet high in dietary fiber decreases the risk of diverticular disease, and this result was not sensitive to the use of different analytic techniques to define dietary fiber. Our findings suggest that the insoluble component of fiber was significantly associated with a decreased risk of diverticular disease, and this inverse association was particularly strong for cellulose.

Associations of plasma carotenoid concentrations and dietary intake of specific carotenoids in samples of two prospective cohort studies using a new carotenoid database

Diet-plasma carotenoid associations were examined in samples of women and men from each cohort in the Nurses' Health Study and the Health Professionals Follow-Up Study. In each sample, participants completed two self-administered food frequency questionnaires with at least a 1-year interval and provided a blood specimen preceding the second food frequency questionnaire. Carotenoid intakes were estimated from values for the five major carotenoids found in human plasma, specifically, alpha- and beta-carotene, beta-cryptoxanthin, lutein, and lycopene, using the United States Department of Agriculture-National Cancer Institute Carotenoid Database, as well as updated values for tomato products. Pearson correlation coefficients were calculated to compare diet-plasma correlations over time by sex after adjustment for recognized covariates. Among nonsmoking women (n = 162), the adjusted diet-plasma carotenoid associations were 0.48 for alpha-carotene, 0.27 for beta-carotene and lutein, 0.32 for beta-cryptoxanthin, and 0.21 for lycopene. Among nonsmoking men (n = 110), diet-plasma correlations were 0.47 for alpha-carotene and lycopene, 0.35 for beta-carotene, 0.43 for beta-cryptoxanthin, and 0.40 for lutein. Correlations between total fruit or vegetable intake and each plasma carotenoid level were not as high as any of the calculated carotenoid intake using the new database values. The correlations observed in this study indicate that the new carotenoid database provides valuable information on specific carotenoid intake and may be useful in epidemiological studies that attempt to account for associations between fruit or vegetable intake and disease.

Folate and vitamin B6 from diet and supplements in relation to risk of coronary heart disease among women

CONTEXT

Hyperhomocysteinemia is caused by genetic and lifestyle influences, including low intakes of folate and vitamin B6. However, prospective data relating intake of these vitamins to risk of coronary heart disease (CHD) are not available.

OBJECTIVE

To examine intakes of folate and vitamin B6 in relation to the incidence of nonfatal myocardial infarction (MI) and fatal CHD.

DESIGN

Prospective cohort study.

SETTING AND PATIENTS

In 1980, a total of 80082 women from the Nurses' Health Study with no previous history of cardiovascular disease, cancer, hypercholesterolemia, or diabetes completed a detailed food frequency questionnaire from which we derived usual intake of folate and vitamin B6.

MAIN OUTCOME MEASURE

Nonfatal MI and fatal CHD confirmed by World Health Organization criteria.

RESULTS

During 14 years of follow-up, we documented 658 incident cases of nonfatal MI and 281 cases of fatal CHD. After controlling for cardiovascular risk factors, including smoking and hypertension and intake of alcohol, fiber, vitamin E, and saturated, polyunsaturated, and trans fat, the relative risks (RRs) of CHD between extreme quintiles were 0.69 (95% confidence interval [CI], 0.55-0.87) for folate (median intake, 696 microg/d vs 158 microg/d) and 0.67 (95% CI, 0.53-0.85) for vitamin B6 (median intake, 4.6 mg/d vs 1.1 mg/d). Controlling for the same variables, the RR was 0.55 (95% CI, 0.41-0.74) among women in the highest quintile of both folate and vitamin B6 intake compared with the opposite extreme. Risk of CHD was reduced among women who regularly used multiple vitamins (RR=0.76; 95% CI, 0.65-0.90), the major source of folate and vitamin B6, and after excluding multiple vitamin users, among those with higher dietary intakes of folate and vitamin B6. In a subgroup analysis, compared with nondrinkers, the inverse association between a high-folate diet and CHD was strongest among women who consumed up to 1 alcoholic beverage per day (RR =0.69; 95% CI, 0.49-0.97) or more than 1 drink per day (RR=0.27; 95% CI, 0.13-0.58).

CONCLUSION

These results suggest that intake of folate and vitamin B6 above the current recommended dietary allowance may be important in the primary prevention of CHD among women.

Telomeres of the linear chromosomes of Lyme disease spirochaetes: nucleotide sequence and possible exchange with linear plasmid telomeres

Bacteria of the spirochaete genus Borrelia have linear chromosomes about 950 kbp in size. We report here that these linear chromosomes have covalently closed hairpin structures at their termini that are similar but not identical to those reported for linear plasmids carried by these organisms. Nucleotide sequence analysis of the chromosomal telomeric regions indicates that unique, apparently functional genes lie within a few hundred bp of each of the telomeres, and that there is an imperfect 26 bp inverted repeat at the two telomeres. In addition, we characterize a major chromosomal length polymorphism within the right telomeric regions of various Borrelia isolates, and show that sequences similar to those near the right telomere are often found on linear plasmids in B. burgdorferi (sensu stricto) isolates from nature. Sequences similar to a number of other regions of the chromosome, including those near the left telomere, were not found on B. burgdorferi plasmids. These observations suggest that there has been historical exchange of genetic information between the linear plasmids and the right end of the linear chromosome.

Cloning, purification, and preliminary characterization by circular dichroism and NMR of a carboxyl-terminal domain of the bacteriophage P22 scaffolding protein

Assembly of double-stranded DNA viruses and bacteriophages involves the polymerization of several hundred molecules of coat protein, directed by an internal scaffolding protein. A 163-amino acid carboxyl-terminal fragment of the 303-amino acid bacteriophage P22 scaffolding protein was cloned, overexpressed, and purified. This fragment is active in procapsid assembly reactions in vitro. The circular dichroism spectrum of the fragment, as well as the 1D-NMR and 15N-1H HSQC spectra of the uniformly-labeled protein, indicate that stable secondary structure elements are present. Determination of the three dimensional packing of these elements into the folded scaffolding protein fragment is underway. Structure-based drug design targeted at structural proteins required for viral assembly may have potential as a therapeutic strategy.

Pancreatic carcinoma cell killing via adenoviral mediated delivery of the herpes simplex virus thymidine kinase gene

OBJECTIVE

Use of adenoviral mediated delivery of the herpes simplex virus thymidine kinase (HSV-TK) gene as a gene therapy strategy for carcinoma of the pancreas.

SUMMARY BACKGROUND DATA

Expression of HSV-TK selectively sensitizes cells to the nucleoside analog ganciclovir (GCV). This strategy has been used to treat other compartmentalized tumor models. Therefore, the containment of pancreatic carcinoma makes it amenable to this gene therapy approach.

METHODS

A recombinant adenoviral vector encoding the HSV-TK gene was used to induce GCV sensitivity and test the potential bystander effect in established pancreatic carcinoma cell lines and patient-derived tumor material. Additionally, Balb/C nude mice were injected intraperitoneally with human pancreatic carcinoma cells and treated with GCV (50 mg/kg per day) for 14 days.

RESULTS

Expression of the HSV-TK gene elicited a significant bystander effect in the presence of GCV. Pancreatic tumor cells injected intraperitoneally into nude mice resulted in significant tumor formation. Treatment of animals with AdCMVHSV/HSV-TK and GCV induced a dramatic decrease in overall tumor burden for up to 8 weeks post-GCV treatment.

CONCLUSIONS

Pancreatic carcinoma cells are highly susceptible to transduction with recombinant adenoviral vector and elicit a potent bystander effect on neighboring tumor cells. Additionally, in vivo treatment of tumor-bearing animals results in dramatic reduction of overall tumor burden, thus providing the rationale for molecular chemotherapy of pancreatic carcinoma.

Complications associated with central venous catheters used for the collection of peripheral blood progenitor cells to support high-dose chemotherapy and autologous stem cell rescue

The purpose of this study was to review the incidence and type of complications associated with the insertion and use of central venous catheters for leukapheresis and high-dose chemotherapy with stem cell rescue. One hundred sixty-seven central venous catheters placed either at the transplant center or by various community surgeons were studied for insertion complications, inability to perform leukapheresis and incidence of infection. The overall incidence of hemo- or pneumothorax was 3.6%. Inability to pherese occurred in 13% of catheters placed by outside surgeons and 6.5% of catheters inserted at the transplant institution. Most often, these were due to malposition of the catheter too high in the superior vena cava or in other veins. Deep venous thrombosis was often related to this malposition and occurred in 4.8% of all patients. Pulmonary embolism was not seen in these patients despite the fact the catheters were often left in place during the thrombotic episode. Early or late-onset infections occurred in 6.5% of patients and were most often exit site infections. The incidence of complications of pheresis catheters is high but might be reduced by more attention to proper placement of the catheter closer to the right atrial/superior vena cava junction, and limiting insertion to a cadre of surgeons familiar with leukapheresis requirements.

Molecular genetic analysis of bacteriophage P22 gene 3 product, a protein involved in the initiation of headful DNA packaging

Bacteriophage P22 DNA packaging events occur in processive series on concatemeric phage DNA molecules. At the point where such series initiate, the DNA is recognized at a site called pac, and most molecular left ends are generated within six short regions called end sites, which are present in a 120 base-pair region surrounding the pac site. The bacteriophage P22 genes 2 and 3 proteins are required for successful generation of these ends and DNA packaging during progeny virion assembly. Mutants lacking the 162-amino-acid gene 3 protein replicate DNA and assemble functional procapsids. In this report we describe the nucleotide changes and DNA packaging phenotypes of a number of missense mutations of gene 3, which give the phage a higher than normal frequency of generalized transduction. In cells infected by these mutants, more packaging events initiate on the host chromosome than in wild-type infections, so the mutations are thought to affect the specificity of packaging initiation. In addition to having this phenotype, these mutations affect the process of phage DNA packaging in detectable ways. They may: (1) alter the target site specificity for packaging; (2) make target site recognition more promiscuous; (3) affect end site utilization; (4) alter the pac site; and (5) cause apparent random DNA packaging series initiation on phage DNA.

Bacteriophage P22 portal protein is part of the gauge that regulates packing density of intravirion DNA

The complex double-stranded DNA bacteriophages assemble DNA-free protein shells (procapsids) that subsequently package DNA. In the case of several double-stranded DNA bacteriophages, including P22, packaging is associated with cutting of DNA from the concatemeric molecule that results from replication. The mature intravirion P22 DNA has both non-unique (circularly permuted) ends and a length that is determined by the procapsid. In all known cases, procapsids consist of an outer coat protein, an interior scaffolding protein that assists in the assembly of the coat protein shell, and a ring of 12 identical portal protein subunits through which the DNA is presumed to enter the procapsid. To investigate the role of the portal protein in cutting permuted DNA from concatemers, we have characterized P22 portal protein mutants. The effects of several single amino acid changes in the P22 portal protein on the length of the DNA packaged, the density to which DNA is condensed within the virion, and the outer radius of the capsid have been determined. The results obtained with one mutant (NT5/1a) indicate no change (+/- 0.5%) in the radius of the capsid, but mature DNA that is 4.7% longer and a packing density that is commensurately higher than those of wild-type P22. Thus, the portal protein is part of the gauge that regulates the length and packaging density of DNA in bacteriophage P22. We argue that these findings make models for DNA packaging less likely in which the packing density is a property solely of the coat protein shell or of the DNA itself.

The assessment of alcohol consumption by a simple self-administered questionnaire

The authors evaluated the reproducibility and validity of alcohol consumption measured by a mailed, self-administered questionnaire in two large prospective studies. Subsamples of 173 women and 136 men from these cohorts completed two food-frequency questionnaires and multiple 1-week diet records (four for women and two for men) and provided a fasting blood sample. Intakes of alcohol reported over the previous year by food frequency questionnaire 2 correlated highly with intake assessed by multiple week diet records completed over this period (Spearman r = 0.90 in women and 0.86 in men). Mean daily alcohol intake as assessed by the diet records and the questionnaires was very similar. Serum high density lipoprotein cholesterol levels were significantly correlated with alcohol intakes estimated from the questionnaire (r = 0.40 in women and 0.35 in men) and for the diet records (r = 0.33 in women and 0.38 in men). Four years after completing the diet records, women were asked to report their alcohol intake of 4 years earlier; this estimate was highly correlated with the diet records (r = 0.84) and with the earlier high density lipoprotein cholesterol (r = 0.40). These data suggest that a simple self-administered questionnaire can provide useful estimates of alcohol intake over an extended period of time in subjects participating in prospective epidemiologic studies.

Fine structure genetic and physical map of the gene 3 to 10 region of the bacteriophage P22 chromosome

The mechanism by which dsDNA is packaged by viruses is not yet understood in any system. Bacteriophage P22 has been a productive system in which to study the molecular genetics of virus particle assembly and DNA packaging. Only five phage encoded proteins, the products of genes 3, 2, 1, 8 and 5, are required for packaging the virus chromosome inside the coat protein shell. We report here the construction of a detailed genetic and physical map of these genes, the neighboring gene 4 and a portion of gene 10, in which 289 conditional lethal amber, opal, temperature sensitive and cold sensitive mutations are mapped into 44 small (several hundred base pair) intervals of known sequence. Knowledge of missense mutant phenotypes and information on the location of these mutations allows us to begin the assignment of partial protein functions to portions of these genes. The map and mapping strains will be of use in the further genetic dissection of the P22 DNA packaging and prohead assembly processes.

Contributions of specific foods to absolute intake and between-person variation of nutrient consumption

Contributions of specific foods and supplements to absolute intake and between-person variance in consumption of 19 macronutrients, vitamins, and minerals were examined using dietary records of all foods consumed over 4 weeks by 194 US nurses aged 34 to 59 years. To measure their contribution to absolute nutrient intake, we ranked foods by the percentage of the population's total nutrient intake that they provided. To assess the degree to which differences in consumption of specific foods explain between-person variability in nutrient intake, we re-ranked the 20 foods contributing most to absolute intake of each nutrient as independent variables in stepwise multiple regression analyses predicting total intake of that nutrient. The increase in percentage of the variance in nutrient intake explained by the addition of a food to the progressively larger list of food items (expressed as the cumulative R2) served as the measure of contribution to variation in intake. Some nutrients had only a few major sources and were assessed relatively well by a small number of foods. For preformed vitamin A without supplements, 10 foods accounted for 82% of the absolute intake and 98% of total variance. The corresponding percentages for absolute intake and total variance, respectively, were 66% and 94% for beta-carotene; 77% and 92% for cholesterol; and 71% and 95% for vitamin C without supplements. In contrast, 20 foods accounted for only 54% of the absolute intake and 73% of the variance for total energy intake; 58% and 89%, respectively, for total carbohydrates; and 59% and 84%, respectively, for potassium.(ABSTRACT TRUNCATED AT 250 WORDS)

Food-based validation of a dietary questionnaire: the effects of week-to-week variation in food consumption

The reproducibility and validity of responses for 55 specific foods and beverages on a self-administered food frequency questionnaire were evaluated. One hundred and seventy three women from the Nurses' Health Study completed the questionnaire twice approximately 12 months apart and also recorded their food consumption for seven consecutive days, four times during the one-year interval. For the 55 foods, the mean of correlation coefficients between frequencies of intake for first versus second questionnaire was 0.57 (range = 0.24 for fruit punch to 0.93 for beer). The mean of correlation coefficients between the dietary records and first questionnaire was 0.44 (range = 0.09 for yellow squash to 0.83 for beer and tea) and between the dietary records and the second questionnaire was 0.52 (range = 0.08 for spinach to 0.90 for tea). Ratios of within- to between-person variance for the 55 foods were computed using the mean four one-week dietary records for each person as replicate measurements. For most foods this ratio was greater than 1.0 (geometric mean of ratios = 1.88), ranging from 0.25 (skimmed milk) to 14.76 (spinach). Correlation coefficients comparing questionnaire and dietary record for the 55 foods were corrected for the within-person variation (mean corrected value = 0.55 for dietary record versus first questionnaire and 0.66 versus the second). Mean daily amounts of each food calculated by the questionnaire and by the dietary record were also compared; the observed differences suggested that responses to the questionnaire tended to over-represent socially desirable foods. This analysis documents the validity and reproducibility of the questionnaire for measuring specific foods and beverages, as well as the large within-person variation for food intake measured by dietary records. Differences in the degree of validity for specific foods revealed in this type of analysis can be useful in improving questionnaire design and in interpreting findings from epidemiological studies that use the instrument.

Variability in portion sizes of commonly consumed foods among a population of women in the United States

The use of food frequency questionnaires for measuring dietary intake has become widespread in epidemiologic studies. It has been suggested that inquiring about a person's usual serving size of each food, in addition to the frequency of consumption, will improve the accuracy of this method. This approach implies that individuals characteristically eat a specific amount of any particular food, and that this amount can be reported with reasonable accuracy. To investigate the variability of portion sizes, the authors analyzed data for 68 commonly consumed foods, based on four one-week weighed diet histories recorded by 194 Boston-area women aged 34-59 years during 1980 and 1981. For each food, total population variance in portion size was partitioned into within-person (intraindividual) and between-person (interindividual) components. For all but seven food items (yogurt, liver, mixed vegetables, watermelon, pancakes/waffles, cold cereal, and cooked cereal) the within-person variance in portion size exceeded the between-person variance. The mean of the within-person to between-person variance ratios, after exclusion of two outlying foods, was 3.4 for untransformed portion sizes, and 3.2 after portion sizes were loge-transformed. Foods with a high within-person variance also tended to have a high between-person variance. The dominance of within-person variance in portion sizes suggests that the concept of usual portion size is complex, and that subjects may experience substantial difficulty in specifying their "usual" portion size. The smaller contribution of between-person variance to the total variance in portion size suggests that specification of a standard portion size by the investigator may not introduce a large error in the estimation of food and nutrient intake.

Energy intake and other determinants of relative weight

The relationships of relative weight to energy intake and to physical activity were studied among 141 females aged 34-59 y. As observed in previous studies Quetelet index (wt/ht2) was inversely related to energy intake (r = -0.11). However, obese women tended to be older (r = 0.16), exercise less (r = -0.30), and drink less alcohol (r = -0.16) than nonobese women. Older women had lower energy intake (r = -0.23) and exercised less (r = -0.12) than younger women. Energy intake and physical activity were positively related (r = 0.23). After adjustment for age, physical activity, alcohol, and smoking, the inverse correlation between relative weight and energy intake was significantly reduced (p = 0.04) from r = -0.11 to r = -0.02. Obese women reported higher intakes of total fat, and relative weight was significantly correlated with intakes of total fat (r = 0.20) and saturated fatty acids (r = 0.16). These data highlight the importance of considering factors that may confound the relationship between energy intake and obesity, and they suggest that fat intake may play a role in obesity that is independent of total energy intake.

The use of a self-administered questionnaire to assess diet four years in the past

The use of a mailed, self-administered, semiquantitative food frequency questionnaire to describe past dietary intake was evaluated in 1984 among a group of 150 Boston-area women who had completed four one-week diet records three to four years previously. Correlation coefficients comparing calorie-adjusted nutrient intakes computed from the questionnaire with those obtained from a compressed version of the questionnaire completed during diet record keeping ranged from 0.44 for total carbohydrate to 0.62 for vitamin C including supplements. Coefficients comparing calorie-adjusted nutrient intakes measured by questionnaire with those assessed by the diet records completed three to four years previously ranged from 0.28 for iron without supplements to 0.61 for total carbohydrate. An evaluation of the incremental contribution provided by several open-ended sections of the questionnaire to the estimation of nutrient intake suggested that in this population most of these items might be eliminated without material loss of information. These findings demonstrate that useful estimates of nutrient intake several years previously can be obtained by a relatively inexpensive, mailed, self-administered questionnaire.

The influence of age, relative weight, smoking, and alcohol intake on the reproducibility of a dietary questionnaire

To evaluate factors that affect the reproducibility of a semi-quantitative food frequency questionnaire used in a large prospective study we compared an extended 99-item questionnaire with a shorter, 61-item form completed by 1497 women with an interval of nine months between. Correlation coefficients for individual items assessed by the two questionnaires were highest for beverages (Spearman r = 0.70). For other foods, coefficients ranged from 0.60 to 0.70 for items eaten frequently (or habitually), to values between 0.34 and 0.45 for foods, such as sweet potatoes and ready made pie, that were eaten less frequently. For food items, the correlation between mean frequency of consumption and the reproducibility coefficient (Spearman r) was 0.51 (p less than 0.01), formally confirming that the reproducibility of measurements was positively associated with frequency of use. Pearson correlation coefficients for calorie-adjusted intakes of nutrients between the two questionnaires ranged from 0.40 for trans-fatty acids to 0.71 for vitamin E (including supplements). These correlation coefficients did not vary materially between subjects in different categories of smoking status or tertiles of age or relative weight. Moderate alcohol use had minimal effect on correlation coefficients, but reproducibility was slightly reduced among heavier drinkers. These data indicate that this self-administered dietary questionnaire can provide reproducible information about individual food and nutrient intakes which is not altered materially by age and a number of important health habits.

Validation of a semi-quantitative food frequency questionnaire: comparison with a 1-year diet record

The validity of a self-administered semi-quantitative food frequency questionnaire was evaluated for a group of 27 men and women aged 20 to 54. Intakes of 18 nutrients computed from the questionnaire were compared with those derived from 1-year diet records completed approximately 18 months earlier. The questionnaire estimates of mean nutrient intake were within 10% of the mean diet record measurements for 11 of the 18 nutrients evaluated, and the difference was less than 25% for all but one nutrient (total vitamin A). Correlation coefficients comparing unadjusted nutrient intakes measured by the two methods ranged from 0.38 (vitamin C) to more than 0.65 (total calories, total fat, saturated fat, polyunsaturated fat, oleic acid, and cholesterol). The overall mean of correlation coefficients comparing intakes of the 18 nutrients measured by questionnaire and by diet record was 0.60. Coefficients for macronutrients decreased somewhat after adjustment for age and gender or caloric intake. The data provide further evidence that a simple and relatively inexpensive questionnaire can provide useful information on dietary intake over an extended period.

Validation of questionnaire information on risk factors and disease outcomes in a prospective cohort study of women

To assess the validity of self-reported illnesses, medical records were reviewed for participants reporting major illnesses on the biennial follow-up questionnaires used in a prospective cohort study which began in 1976. In over 90% of cases of cancer of the breast, skin, large bowel, and thyroid, histopathology reports confirmed the subjects' self-report. Lower levels of confirmation were obtained for cancers of the lung, ovary, and uterus. Application of strict diagnostic criteria also gave lower levels of confirmation for myocardial infarction (68%) and stroke (66%). Among random samples of women reporting fractures and hypertension all records obtained confirmed self-reports. For self-reported elevated cholesterol levels 85.7% of self-reports were confirmed. Self-report is a valuable epidemiologic tool but may require additional documentation when the disease is diagnostically complex.

Validation of questionnaire information on risk factors and disease outcomes in a prospective cohort study of women

To assess the validity of self-reported illnesses, medical records were reviewed for participants reporting major illnesses on the biennial follow-up questionnaires used in a prospective cohort study which began in 1976. In over 90% of cases of cancer of the breast, skin, large bowel, and thyroid, histopathology reports confirmed the subjects' self-report. Lower levels of confirmation were obtained for cancers of the lung, ovary, and uterus. Application of strict diagnostic criteria also gave lower levels of confirmation for myocardial infarction (68%) and stroke (66%). Among random samples of women reporting fractures and hypertension all records obtained confirmed self-reports. For self-reported elevated cholesterol levels 85.7% of self-reports were confirmed. Self-report is a valuable epidemiologic tool but may require additional documentation when the disease is diagnostically complex.

Plasmid vectors useful in the study of translation initiation signals

The construction and characterization of plasmid vectors useful in the analysis of translation initiation signals in Escherichia coli and in the construction of lacZ gene hybrids are described. Transcription on the vectors proceeds from a cAMP-independent lac promoter through several restriction sites into a truncated lacZ structural gene lacking its first eight codons. Because this gene has no translation initiation signal, its level of expression is extremely low. A DNA fragment containing a translation start signal can be inserted between the promoter and truncated lacZ gene to produce a hybrid protein with functional beta-galactosidase activity. The vectors described here differ in sequence between the EcoRI cloning site and the lacZ gene to allow easy, in-frame joining of DNA containing a translation initiation signal to the lacZ gene. Cells containing plasmids can be screened directly for in-frame inserts by colony color on indicator plates.

Reproducibility and validity of a semiquantitative food frequency questionnaire

The aim of this study was to evaluate the reproducibility and validity of a 61-item semiquantitative food frequency questionnaire used in a large prospective study among women. This form was administered twice to 173 participants at an interval of approximately one year (1980-1981), and four one-week diet records for each subject were collected during that period. Intraclass correlation coefficients for nutrient intakes estimated by the one-week diet records (range = 0.41 for total vitamin A without supplements to 0.79 for vitamin B6 with supplements) were similar to those computed from the questionnaire (range = 0.49 for total vitamin A without supplements to 0.71 for sucrose), indicating that these methods were generally comparable with respect to reproducibility. With the exception of sucrose and total carbohydrate, nutrient intakes from the diet records tended to correlate more strongly with those computed from the questionnaire after adjustment for total caloric intake. Correlation coefficients between the mean calorie-adjusted intakes from the four one-week diet records and those from the questionnaire completed after the diet records ranged from 0.36 for vitamin A without supplements to 0.75 for vitamin C with supplements. Overall, 48% of subjects in the lowest quintile of calorie-adjusted intake computed from the diet records were also in the lowest questionnaire quintile, and 74% were in the lowest one of two questionnaire quintiles. Similarly, 49% of those in the highest diet record quintile were also in the highest questionnaire quintile, and 77% were in the highest one or two questionnaire quintiles. These data indicate that a simple self-administered dietary questionnaire can provide useful information about individual nutrient intakes over a one-year period.