Dietary intake of acrylamide and pancreatic cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.

BACKGROUND: In 1994, acrylamide (AA) was classified as a probable human carcinogen by the International Agency for Research on Cancer. In 2002, AA was discovered at relatively high concentrations in some starchy, plant-based foods cooked at high temperatures. PATIENTS AND METHODS: A prospective analysis was conducted to evaluate the association between the dietary intake of AA and ductal adenocarcinoma of the exocrine pancreatic cancer (PC) risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort using Cox regression modeling. EPIC includes >500,000 men and women aged 35-75 at enrollment from 10 European countries. AA intake was estimated for each participant by combining questionnaire-based food consumption data with a harmonized AA database derived from the EU monitoring database of AA levels in foods, and evaluated in quintiles and continuously. RESULTS: After a mean follow-up of 11 years, 865 first incident adenocarcinomas of the exocrine pancreas were observed and included in the present analysis. At baseline, the mean dietary AA intake in EPIC was 26.22 µg/day. No overall association was found between continuous or quintiles of dietary AA intake and PC risk in EPIC (HR:0.95, 95%CI:0.89-1.01 per 10 µg/day). There was no effect measure modification by smoking status, sex, diabetes, alcohol intake or geographic region. However, there was an inverse association (HR: 0.73, 95% CI: 0.61-0.88 per 10 µg/day) between AA intake and PC risk in obese persons as defined using the body mass index (BMI, ≥ 30 kg/m(2)), but not when body fatness was defined using waist and hip circumference or their ratio. CONCLUSIONS: Dietary intake of AA was not associated with an increased risk of PC in the EPIC cohort.

Impaired replication of protease inhibitor-resistant HIV-1 in human thymus.

Many HIV-1-infected patients treated with protease inhibitors (PI) develop PI-resistant HIV-1 variants and rebounds in viremia, but their CD4+ T-cell counts often do not fall. We hypothesized that in these patients, T-cell counts remain elevated because PI-resistant virus spares intrathymic T-cell production. To test this, we studied recombinant HIV-1 clones containing wild-type or PI-resistant protease domains, as well as uncloned isolates from patients, in activated peripheral blood mononuclear cells, human thymic organ cultures and human thymus implants in SCID-hu Thy/Liv mice. In most cases, wild-type and PI-resistant HIV-1 isolates replicated to similar degrees in peripheral blood mononuclear cells. However, the replication of PI-resistant but not wild-type HIV-1 isolates was highly impaired in thymocytes. In addition, patients who had PI-resistant HIV-1 had abundant thymus tissue as assessed by computed tomography. We propose that the inability of PI-resistant HIV-1 to replicate efficiently in thymus contributes to the preservation of CD4+ T-cell counts in patients showing virologic rebound on PI therapy.

Isolation of a new human retrovirus from West African patients with AIDS.

The etiological agent of AIDS, LAV/HTLV-III, is common in Central Africa but is not endemic in other areas of that continent. A novel human retrovirus, distinct from LAV/HTLV-III, has now been isolated from two AIDS patients from West Africa. Partial characterization of this virus revealed that it has biological and morphological properties very similar to LAV but that it differs in some of its antigenic components. Although the core antigens may share some common epitopes, the West African AIDS retrovirus and LAV differ substantially in their envelope glycoproteins. The envelope antigen of the West African virus can be recognized by serum from a macaque with simian AIDS infected by the simian retrovirus termed STLV-IIImac, suggesting that the West African AIDS virus may be more closely related to this simian virus than to LAV. Hybridization experiments with LAV subgenomic probes further established that this new retrovirus, here referred to as LAV-II, is distantly related to LAV and distinct from STLV-IIImac.

HIV-1 reverse transcription. A termination step at the center of the genome.

During HIV-1 reverse transcription, the plus-strand of viral DNA is synthesized as two discrete segments. We show here that synthesis of the upstream segment terminates at the center of the genome after an 88 or 98 nucleotide strand displacement of the downstream segment, initiated at the central polypurine tract. Thus, the final structure of unintegrated linear HIV-1 DNA includes a central plus-strand overlap. In vitro reconstitution using only purified reverse transcriptase with appropriate DNA hybrids gave rise to efficient and accurate termination, which was dramatically amplified in the context of strand displacement. Mutation of the sequence immediately upstream of the termination sites almost completely abolished termination both in infected cells and in vitro. This mutation profoundly impaired replication of HIV-1. We conclude that proper central plus-strand termination, mediated by a novel cis-active termination sequence, is a key step in HIV-1 replication.

Cis elements and trans-acting factors involved in the RNA dimerization of the human immunodeficiency virus HIV-1.

The retroviral genome consists of two identical RNA molecules joined at their 5' ends by the Dimer Linkage Structure (DLS). To study the mechanism of dimerization and the DLS of HIV-1 RNA, large amounts of bona fide HIV-1 RNA and of mutants have been synthesized in vitro. We report that HIV-1 RNA forms dimeric molecules and that viral nucleocapsid (NC) protein NCp15 greatly activates dimerization. Deletion mutagenesis in the RNA 5' 1333 nucleotides indicated that a small domain of 100 nucleotides, located between positions 311 to 415 from the 5' end, is necessary and sufficient to promote HIV-1 RNA dimerization. This dimerization domain encompasses an encapsidation element located between the 5' splice donor site and initiator AUG of gag and shows little sequence variations in different strains of HIV-1. Furthermore, cross-linking analysis of the interactions between NC and HIV-1 RNA (311 to 415) locates a major contact site in the encapsidation element of HIV-1 RNA. The genomic RNA dimer is tightly associated with nucleocapsid protein molecules in avian and murine retroviruses, and this ribonucleoprotein structure is believed to be the template for reverse transcription. Genomic RNA-protein interactions have been analyzed in human immunodeficiency virus (HIV) virions and results showed that NC protein molecules are tightly bound to the genomic RNA dimer. Since retroviral RNA dimerization and packaging appear to be under the control of the same cis element, the encapsidation sequences, and trans-acting factor, the NC protein, they are probably related events in the course of virion assembly.

Analysis of HIV cross-resistance to protease inhibitors using a rapid single-cycle recombinant virus assay for patients failing on combination therapies.

OBJECTIVE: To assess the patterns of HIV phenotypic cross-resistance to protease inhibitors (PI) in patients experiencing viral load rebound on combination therapy including a PI. METHODS: Phenotypic analysis of sensitivity to indinavir, nelfinavir, saquinavir, ritonavir and amprenavir was carried out using a single-cycle recombinant virus assay. Viral protease was sequenced by automated dideoxynucleotide chain termination. RESULTS: Of the 108 patients studied, 68 had received indinavir, 50 ritonavir, 25 saquinavir and eight nelfinavir. The majority (71%) had received only one PI. The incidence of cross-resistance between indinavir, nelfinavir, ritonavir and saquinavir was high (60-90%). Cross-resistance to amprenavir was less frequent (37-40%). However there was some correlation between levels of sensitivity to amprenavir and indinavir (r2 = 0.34; P < 0.01). Conversely, the correlation between levels of sensitivity to indinavir and saquinavir was poor (r2 = 0.25), particularly for patients who had not received saquinavir. The degree of cross-resistance correlated with the level of resistance and with the total number of mutations in the protease gene (P < 0.05, chi square test) but could not be significantly correlated to any one particular mutation or combination of mutations. Mutation 184V was significantly associated with cross-resistance to amprenavir, with no mutations at codon 50 observed, while mutations associated with cross-resistance to saquinavir differed according to the treatment received. CONCLUSIONS: These results suggest that, although the total number of protease mutations correlates with the degree of cross-resistance, the specific mechanisms accounting for primary resistance and for cross-resistance may be different.

Efficacy of a five-drug combination including ritonavir, saquinavir and efavirenz in patients who failed on a conventional triple-drug regimen: phenotypic resistance to protease inhibitors predicts outcome of therapy.

OBJECTIVE: to assess the safety and efficacy of a combination of ritonavir, efavirenz and two recycled nucleosides in patients who failed on a conventional triple-drug regimen including indinavir or ritonavir. METHODS: An open label study of ritonavir (100 mg twice daily), saquinavir (1000 mg twice daily), efavirenz (600 mg per day) and nucleoside analogues in 32 saquinavir- and efavirenz-naive protease inhibitor-experienced patients. Patients were included on the basis of plasma levels of HIV RNA above 5000 copies/ml while on conventional antiretroviral therapy. Phenotypic resistance and genotypic resistance mutations to saquinavir were assessed at baseline. Peak and trough plasma levels of saquinavir were monitored throughout the study. RESULTS: Median CD4 cell counts and median plasma HIV RNA at baseline were 258 x 10(6)/l and 4.31 log10 copies/ml, respectively. The plasma viral load decreased by a median of 1.20 log10 copies/ml and the CD4 cell count increased by a median 60 x 10(6) cells/l at week 24 of therapy. Seventy-one per cent of the patients achieved a plasma viral load < 500 copies/ml and 45% achieved a viral load < 50 copies/ml. Patients exhibiting phenotypic resistance to saquinavir at baseline experienced a median decrease in HIV RNA of 0.91 log10 copies/ml at week 24 of therapy, as compared with a decrease of 1.52 log10 copies/ml in those exhibiting sensitive viral strains (P = 0.03). Genotypic resistance to saquinavir was not predictive of virologic failure. CONCLUSION: Our results indicate that the combination of ritonavir, saquinavir and efavirenz is safe and effective at 24 weeks in over two-thirds of patients who previously failed on highly active antiretroviral therapy, and that the determination of phenotypic resistance may be of greater value than the detection of resistance mutations to predict the outcome of salvage therapy in this setting.

Association between breast cancer and family malignancies.

In a case-control study, the relationship between a family history of cancer of the breast, ovary, colon, uterus or prostate and the risk of breast cancer was investigated. The data consisted of family histories from 495 breast cancer cases and 785 controls aged 20-56 years. A positive association was found between the occurrence of breast cancer and a history of breast cancer in the families of the subjects affected. This relationship increased linearly with both the degree of kinship of the affected relatives and with their number. The risk of breast cancer associated with other types of cancer in the family was not significantly different from unity.

Reversion of a polymerase-defective integrated HIV-1 genome.

The 8E5 clonal cell line, derived from HIV-1-infected CEM cells, carries a single, reverse transcriptase (RT)-defective copy of an integrated HIV genome. The absence of RT production is a consequence of a frame shift in the pol gene, due to the addition of a single base at position 3241. We report here that 8E5 cells produce an infectious virus that can be serially passaged on CD4+ lymphoid cells. This virus (8E5R) is RT positive, but displays a slow replication profile, together with a reduced cytopathic effect. The nucleotide sequence of a segment of the pol region produced by PCR amplification of DNA from 8E5R-infected cells shows that the single nucleotide insertion characteristic of the 8E5 genome had been corrected. The same reversion event was also found to occur in most single-cell clones derived from the 8E5 cell line. Because this cell line is used in many laboratories, notably as a standard for PCR quantitation, and is generally considered as unable to produce infectious virus, our findings should prompt investigators to use particular care in the handling of these cells.

Kinetic analysis of HIV-1 early replicative steps in a coculture system.

During an acute human immunodeficiency virus (HIV) infection in vitro, different forms of unintegrated viral DNA accumulate in target cells. They include linear full-length HIV DNA molecules, which are the precursors of the integrated provirus, and two types of circular molecules (with one or two LTRs), whose role and mode of formation are not fully understood. To evaluate the intracellular fate of HIV unintegrated DNA, and to follow the formation of the two types of circular DNA molecules, the nuclear transport of viral DNA, and its integration in host cell DNA, we have designed a "DNA chase" assay. This assay is based on cocultivation of persistently HIV-1-infected H9 cells with uninfected MT4, allowing rapid accumulation of viral DNA, which is then blocked by addition of AZT. In this highly efficient, synchronous, one-step cycle infection system, HIV linear DNA can be detected on Southern blots as early as 4 hr after the start of the coculture. Subsequently, viral DNA that had been synthesized before the addition of AZT could be "chased," establishing that almost all linear DNA molecules are rapidly transported to the nucleus, where they are either processed into the two types of circles or integrated. We could estimate that from the number of viral DNA molecules synthesized in 6 hr in this system, at least a third will become integrated and another third will circularize within 24 hr.

Inhibition of HIV type 1 reverse transcriptase assay by nucleases produced by contaminating mycoplasmas.

Mycoplasmal contamination of HIV-1-infected cells has been found to induce reduction of reverse transcriptase (RT) activity; however, the exact mechanism of this phenomenon was not clearly elucidated. Our results indicate that the apparent reduction in RT activity is due to a calcium-dependent nuclease(s) that is (are) produced by contaminating mycoplasmas. The interference with the RT assay was found to be due to the degradation of products of the RT activity. Addition of EGTA at a 1 mM concentration was sufficient to remove the inhibitory effect. The particular HIV-1-producing cell line that was under study was found to be contaminated with Mycoplasma fermentans and Mycoplasma pirum and the latter was isolated in pure culture. Nuclease activity was also observed with pure cultures of mycoplasmas from different species. The activity was found to be of the endonuclease type because it was active with both supercoiled and linear DNAs.

Primary and recombinant HIV type 1 strains resistant to protease inhibitors are pathogenic in mature human lymphoid tissues.

Preserved peripheral CD4+ T cell counts despite virologic failure in patients undergoing protease inhibitor (PI)-containing antiviral regimens are a frequent occurrence in human immunodeficiency virus (HIV) disease. One hypothesis to explain the relative sparing of CD4+ T cells is that HIV strains exhibiting PI resistance concomitantly are attenuated in terms of cytopathicity for mature T cells. To test this hypothesis, we used a three-dimensional human tonsil histoculture microenvironment to assess the pathogenic potential of a panel of primary and recombinant HIV-1 strains derived from patients experiencing PI failure. All the viruses tested replicated efficiently in these cultures and, in some cases, better than comparable wild-type viral isolates. Furthermore, the PI-resistant strains depleted CD4+ T cells potently and comparably with wild-type isolates in these ex vivo lymphoid tissues. These results demonstrate that PI-resistant viruses are not inherently less pathogenic for mature T cells. Therefore, the sustained peripheral lymphocyte counts in patients with selective virologic failure may be due to specific defects in viral replication in other cell compartments or to an undefined host adaptation to viral infection during PI therapy.

Variations in the risk of breast cancer associated with a family history of breast cancer according to age at onset and reproductive factors.

In a case-control study of 495 breast cancer patients and 785 controls between 20 and 56 years of age, the risk of breast cancer associated with a family history of breast cancer was studied according to age and reproductive factors. The familial risk of breast cancer was not significantly modified by age at onset, age at menarche, number of children, age at first full-term pregnancy, menstrual cycle length or age at menopause. However, the familial risk significantly increased with the number of abortions (p < 0.05) and seemed to decrease after a natural menopause (p = 0.08). These results suggest that a familial predisposition to breast cancer exerts the same influence during the first six decades of life, except maybe when there are isolated or repeated events such as abortions or artificially imposed menopause, in which case the risk is apparently greater.

Relative validity and reproducibility of a French dietary history questionnaire.

BACKGROUND: A self-administered dietary history questionnaire, especially developed for use in a large French prospective cohort study, was tested for accuracy of food intake measurement by comparing it to the average of 9-12 24-hour recalls. This questionnaire was structured according to the French meal pattern. An important feature of the questionnaire was the separation into a quantification part and qualification part. The first part quantifies consumption by frequency and portion sizes per food group or food item. The second part provides more detailed qualitative information on separate items within one food group. The total number of food items in the questionnaire was 238. METHODS: The questionnaire was administered twice to 119 study subjects, with an interval of approximately one year (1990-1991). During that year, 24-hour recalls were carried out monthly. Reproducibility and relative validity of the questionnaire were assessed. RESULTS: The correlation coefficients for reproducibility ranged from 0.40 to 0.74 for foods and from 0.54 to 0.75 for nutrients. The correlation coefficients for relative validity ranged from 0.10 to 0.71 for foods and from 0.29 to 0.81 for nutrients (adjustment for total energy and attenuation for nutrients). Percentage of subjects classified in the same or adjacent quintile by questionnaire as well as by 24-hour recall was on average 76% for foods and 72% for nutrients. CONCLUSIONS: These data indicate that this questionnaire can be used to classify study subjects according to their food or nutrient intake over a one-year period, within a known degree of precision.

Oral contraceptives and breast cancer: a French case-control study.

The relationship between the risk of breast cancer and oral contraceptive use was investigated in a case-control study conducted in France between 1983 and 1987 in five public hospitals. Some 464 cases aged 25 to 56 years and 542 matched controls were interviewed about their history of the use of oral contraceptives (OC). Results are given for the entire population and for the subgroup of 358 and 379 premenopausal cases and controls. The multivariate relative risk estimate, for ever user, was 1.5 (p less than 0.01) in the whole group as well as in the premenopausal subgroup (p less than 0.02). However, there was no evidence that the effect varied appreciably according to duration of use, age at first use, use before first full-term pregnancy (FFTP) and time since first or last use. The risk was not altered for any particular brand of OC. We conclude that, because of the widespread attention given to the relationship between OC use and breast cancer, information bias might be responsible for part of the excess in risk observed among OC ever users.

PIP: The relationship between the risk of breast cancer and oral contraceptive (OC) use was investigated in a case-control study conducted in France between 1983-87 in 5 public hospitals. Some 464 cases ages 25-56 years and 542 matched controls were interviewed about their history of OC use. Results are provided for the entire population and for the subgroups of 358 and 379 premenopausal cases and controls. The multivariate relative risk estimate, for ever-use, was 1.5 (p0.01) in the entire group as well as in the premenopausal subgroup (p0.02). However, there was no evidence that the effect varied appreciably according to the duration of use, age at 1st use, use prior to 1st fullterm pregnancy, and time since 1st or last use. The risk was not altered for any particular OC brand. The authors conclude that because of the widespread attention given to the relationship between OC use and breast cancer, information bias might be responsible for a part of the excess of risk observed among OC ever-users.

Prevalence of nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance-associated mutations and polymorphisms in NNRTI-naïve HIV-infected patients.

BACKGROUND: The efficacy of treatment containing nonnucleoside reverse transcriptase inhibitors (NNRTIs) could be compromised in NNRTI-naïve patients already harboring a virus resistant to NNRTIs. On the contrary, hypersusceptibility to NNRTIs in patients having failed nucleoside reverse transcriptase inhibitor (NRTI)-containing regimens has been described and has been associated with improved outcome. METHOD: We assessed the prevalence of NNRTI resistance-associated mutations or polymorphisms in 146 antiretroviral-naïve patients and in 181 HIV-infected patients who were given an NNRTI-based regimen. We phenotypically evaluated the NNRTI susceptibility of 41 strains presenting with amino acid substitutions at positions involved in NNRTI resistance. RESULTS: In the 268 genotypically analyzable samples, the overall prevalence of NNRTI resistance-associated mutations was 2% (6/268 patients). The prevalence of strains with amino acid substitutions at reverse transcriptase (RT) gene positions (A98, K101, K103, V106, V108, V179) involved in NNRTI resistance was 15%. Hypersusceptibility to NNRTI was rare (2%, 1/41) in those samples. RT substitutions at positions involved in NNRTI resistance were not associated with a significantly worse virologic outcome in NNRTI-treated patients. Our understanding of small shifts in IC50 values (higher or lower) toward NNRTI is very limited. The significance of many RT mutations on NNRTI susceptibility is not clear. CONCLUSION: In contrast to resistance mutations, RT substitutions at positions involved in NNRTI resistance are frequent. They are not associated with a worse virologic outcome or with decreased phenotypic susceptibility to NNRTIs. It may be prudent not to rule out the use of NNRTIs in patients with small shifts in IC50 values or poorly understood mutations.

[Relation between mortality in cancer of the pancreas and food and tobacco consumption in France]. / Etude de la relation entre la mortalité par cancer du pancréas et certaines consommations alimentaires et de tabac en France.

The relationship is given between French pancreatic cancer mortality rates form 1968 to 1976, and some nutritional variables and tobacco. Positive correlations were found between the death rate from pancreatic cancer and sugar, egg and cereal consumption; however, a negative correlation was found with tobacco consumption. A stepwise multiple regression procedure showed an association between the mortality rate from cancer of the pancreas and meat and oil consumption when age had been taken into account.

Breast cancer and oral contraceptives: a review.

The relationship between oral contraceptive use and breast cancer was investigated in 22 major epidemiological studies, which are reviewed in this paper. The overall risk ratio was never found to increase when computed among all users vs. nonusers. Risk increases were found in some studies within specific subgroups; but in general, if any risk exists, it is not much more than one. Future studies should focus specifically on women under age 25, on women before a first full-term pregnancy and, to a lesser extent, on perimenopausal women and on women who have had a benign breast disease.

PIP: This paper reviews the findings of the 22 major epidemiologic studies that have investigated the relationship between breast cancer and oral contraceptive (OC) use. Although the findings are discrepant, they tend to rule out the hypothesis of a large increase in the risk of breast cancer in OC users compared to nonusers, at least among women over 25 years of age. Moreover, rates of breast cancer have not been shown to increase with increasing duration of OC use. In general, if a risk has been found, it has not exceeded 1. In certain specific subgroups, particularly women under age 25 years and women who used OCs before 1st pregnancy, the risk of breast cancer has been found to be increased in selected studies but not in other studies. To clarify these discrepant findings, it is recommended that future studies focus on women under age 25 years, on women before a 1st full-term pregnancy, and, to a lesser extent, on perimenopausal women and those who have had a benign breast disease. It should be kept in mind that widespread use of OCs may be too recent to assess possible carcinogenic effects. The absence of a consistent pattern of risk findings in the literature may in part reflect methodological inadequacies, including an sufficient number of cases or biased selection of subjects.

[Breast cancer and use of antihypertensive drugs and oral contraceptives: results of a case-control study (author's transl)]. / Etude de la liaison entre le cancer du sein et la prise de médicaments hypotenseurs et contraceptifs oraux: résultats d'une étude cas-témoins.

A case control study in breast cancer was conducted in France between 1976 and 1980. 1 031 patients with histologically confirmed cancer of the breast were entered into the study. Each was matched on age (+/- 5 years) to two controls hospitalized in the same clinic for a benign disease. We have specially studied the anti-hypertensive drugs, and the oral contraceptives. We found no difference between cancer patients and controls concerning their consumption of anti-hypertensive drugs, whether containing reserpine or not, and their consumption of oral contraceptives. However, there is a relation between the use of oral contraceptives and the age, family status and social class of women. After adjustment on these factors, we found a 1.62 relative risk of developing a cancer of the breast among the women using oral contraceptives (p less than 0.02).

[A study of various smoking cessation programs based on close to 1000 volunteers recruited from the general population: 1-month results]. / Une étude de différents programmes de désintoxication tabagique portant sur près de 1000 volontaires recrutés dans la population générale: résultats à 1 mois.

The harmful effect of tobacco on health is well known. To help smokers to stop smoking, a study was designed in 1987 to assess the efficacy of two treatments and the advantage of combining them. The treatments, nicotine chewing gum and acupuncture, were randomly allocated. The 996 subjects required are now included. The characteristics of the participants, the number of nicotine gums used as well as the need for a cigarette are described. Cessation rates in the four groups, one month after the beginning of the treatment, differed significantly (p less than 5%). The efficacy of acupuncture was not shown (abstinence rates of 22 and 23% for the active and placebo groups respectively), whereas the efficacy of nicotine gum was (26 and 19% for the active and placebo groups respectively). The interest of the association of the two treatments was not observed.