[Group Training of Patients with Chronic Lung Diseases under Outpatient Conditions - Recommendations of the Working Group Lung Sports in Germany and the German Airways League]. / Ambulanter Lungensport und körperliches Training bei Patienten mit Atemwegs- und Lungenkrankheiten.

To improve acceptance and use of physical training by patients with chronic lung diseases, recommendations for performing lung exercises on an outpatient basis in a group setting are given by experts in physical training, sports therapists and pulmonologists. The evidence-based positive effects of physical training were analyzed for asthma , COPD, interstitial lung diseases, cystic fibrosis, lung carcinoma, and pulmonary hypertension. The requirements for lung exercises in outpatient groups as well as compensation by care providers were given on the basis of legal regulations. Furthermore, the main items of the training units as well as supervision by specially trained group leaders in relation to the severity of the underlying lung disease are described. Finally, aspects of safety of the participating patients are discussed, including the prevention of infection with corona-2-virus.

Towards an in vitro fibrogenesis model of human vocal fold scarring.

BACKGROUND: Vocal fold (VF) scarring remains a therapeutic dilemma and challenge in modern laryngology. To facilitate corresponding research, we aimed to establish an in vitro fibrogenesis model employing human VF fibroblasts (hVFF) and the principles of macromolecular crowding (MMC). METHODS: Fibrogenesis was promoted by addition of transforming growth factor-ß1 to standard medium and medium containing inert macromolecules (MMC). Hepatocyte growth factor (HGF) and Botox type A were tested for their antifibrotic properties in various doses. Experiments were analyzed with respect to the biosynthesis of collagen, fibronectin, and α-smooth muscle actin using immunofluorescence, silver stain and western blot. RESULTS: MMC led to favourable enhanced deposition of collagen and other extracellular matrix components, reflecting fibrotic conditions. Low doses of HGF were able to dampen profibrotic effects. This could not be observed for higher HGF concentrations. Botox type A did not show any effects. CONCLUSION: Based on the principles of MMC we could successfully establish a laryngeal fibrogenesis model employing hVFF. Our finding of dose-dependent HGF effects is important before going into clinical trials in humans and has never been shown before. Our model provides a novel option to screen various potential antifibrotic compounds under standardized conditions in a short time.

Multiple sclerosis and risk of Parkinson's disease: a Danish nationwide cohort study.

BACKGROUND AND PURPOSE: Case reports have observed a co-occurrence of multiple sclerosis (MS) and Parkinson's disease (PD) and it has been hypothesized that MS lesions could affect dopaminergic pathways causing parkinsonism. Our aim was to examine the association between MS and PD in a historically prospective cohort study using Danish nationwide register data. METHODS: Multiple sclerosis patients identified in the Multiple Sclerosis Registry were followed for PD from 1977 to 2011 in the National Patient Register. As measures of relative risk, ratios of observed to expected incidence rates of first hospitalization for PD amongst persons with MS were used, i.e. standardized incidence ratios (SIRs) with 95% confidence intervals (CIs). RESULTS: Amongst 15,557 MS patients 26 cases of PD were observed versus 26.51 expected, reflecting no overall increased risk of PD (SIR 0.98, 95% CI 0.67-1.44). Similar estimates were seen for female (SIR 0.99, 95% CI 0.58-1.67) and male MS patients (SIR 0.97, 95% CI 0.55-1.72). Likewise, no increased risk of PD amongst MS patients was observed in a robustness analysis backdating the date of diagnosis of PD by 5 years to account for the time lag between disease onset and first hospital contact with PD (SIR 0.57, 95% CI 0.32-1.00). CONCLUSION: Our data do not suggest an increased risk of PD amongst patients with MS.

Socio-demographic factors, reproductive history and risk of osteoarthritis in a cohort of 4.6 million Danish women and men.

OBJECTIVE: Studies addressing possible socio-demographic and reproductive factors in the aetiology of osteoarthritis (OA) are few. We studied possible influences of educational level, household income, marital status and parenting patterns on OA risk overall and at anatomical sites. METHOD: We linked national register data about socio-demographic variables, reproductive histories and OA hospital contacts to a cohort of 4.6 million Danes. Ratios of first OA hospitalisation rates (RRs) were calculated using Poisson regression. RESULTS: Overall, 100,437 women and 92,020 men had a first OA hospital contact during 91.5 million person-years between 1982 and 2008. Short education, low income and married status were significantly associated with increased OA risk, and persons with children were at higher risk of OA(overall) (RR=1.10 in women; RR=1.22 in men), OA(knee) (RRs 1.14; 1.28), OA(back) (RRs 1.18; 1.33), and OA(hand) (RRs 1.21; 1.43), but not of OA(hip) (RRs 0.96; 1.00) than persons without children. The RR of OA(overall) increased by a factor of 1.05 in women and 1.04 in men per additional child, most notably for OA(knee) in women (1.10 per child). CONCLUSION: Risk of OA hospitalisation was highest among married persons and persons with short education or low income. The similar or even stronger associations with reproductive factors in men than women suggest that unmeasured lifestyle factors rather than biological factors associated with pregnancy might explain the higher OA risk in persons with children. However, the particularly strong association between parity and risk of OA(knee) in women is compatible with a role of pregnancy-associated factors.

In situ and invasive squamous cell carcinoma of the vulva in Denmark 1978-2007-a nationwide population-based study.

OBJECTIVE: To determine the incidence of vulvar carcinoma in situ (CIS) and cancer of squamous cell (SC) origin in Denmark in the period 1978-2007. METHODS: Using the nationwide Danish Cancer Registry, we identified 980 women diagnosed with vulvar CIS 1978-2003 (67.8% were SC) and 2455 women diagnosed with vulvar cancer 1978-2007 (76.0% were SC). Analysis was restricted to vulvar CIS and cancer of SC origin. We assessed age-specific incidence rates, age-standardized incidence rates, and distribution of stage at diagnosis. Poisson regression analysis was used to estimate the average annual percentage change. RESULTS: During the study period the age-standardized incidence rate of vulvar SC CIS increased by 1.97% per year (95% CI: 0.99% to 2.96%) with a tendency toward a steeper increase among women younger than 50 years. The age-standardized incidence rate of vulvar SC cancer showed a stable or slightly increasing pattern. However, among women below 60 years of age a significantly increasing trend was observed (1.60% per year; 95% CI: 0.50% to 2.71%). The distribution in the extent of vulvar SC cancer at diagnosis showed a tendency toward a higher proportion being diagnosed with localized disease in the more recent calendar years. CONCLUSIONS: The incidence rates of vulvar SC CIS and vulvar SC cancer among women below the age of 60 years have increased since 1978. Human papillomavirus (HPV) could explain the increase and thus, the recent introduction of HPV vaccination may in the future result in a notable reduction of vulvar malignancies.

Power and false-positive rate in QTL detection with near-isogenic line libraries.

Libraries of near-isogenic lines (NILs) were used for quantitative trait locus (QTL) detection in model species and economically important crops. The experimental design and genetic architecture of the considered traits determine the statistical properties of QTL detection. The objectives of our simulation study were to (i) investigate the population sizes required to develop NIL libraries in barley and maize, (ii) compare NIL libraries with nonoverlapping and overlapping donor segments and (iii) study the number of QTLs and the size of their effects with respect to the power and the false-positive rate of QTL detection. In barley, the development of NIL libraries with target segment lengths of 10 c and marker distances of 5 cM was possible using a BC(3)S(2) backcrossing scheme and population sizes of 140. In maize, population sizes larger than 200 were required. Selection for the recipient parent genome at markers flanking the target segments with distances between 5 and 10 cM was required for an efficient control of the false-positive rate. NIL libraries with nonoverlapping donor chromosome segments had a greater power of QTL detection and a smaller false-positive rate than libraries with overlapping segments. Major genes explaining 30% of the genotypic difference between the donor and recipient were successfully detected even with low heritabilities of 0.5, whereas for minor genes explaining 5 !or 10%, high heritabilities of 0.8 or 0.9 were required. The presented results can assist geneticists and breeders in the efficient development of NIL libraries for QTL detection.

National cohort study of reproductive risk factors for rheumatoid arthritis in Denmark: a role for hyperemesis, gestational hypertension and pre-eclampsia?

OBJECTIVES: While reproductive factors might plausibly be involved in the aetiology of rheumatoid arthritis (RA), the female predominance remains unexplained. A study was undertaken to address the possible impact of live births, pregnancy losses and pregnancy complications on the subsequent risk of RA in a nationwide cohort study. METHODS: National register data were used to link reproductive histories and later RA hospitalisations in a cohort of 4.4 million Danes. As a measure of relative risk associated with different reproductive histories, ratios of first inpatient RA hospitalisation rates (RRs) were used with 95% confidence intervals (CIs) obtained by Poisson regression analysis. RESULTS: Overall, 7017 women and 3041 men were admitted to hospital with RA in 1977-2004 (88.8 million person-years). The risk of RA was inversely associated with age at birth of first child in both women and men (p for trend <0.001). Overall, nulliparity and a history of pregnancy loss were not associated with RA risk but, compared with one-child mothers, women with two (RR 0.84; 95% CI 0.78 to 0.90) or three (RR 0.83; 95% CI 0.77 to 0.91) children were at reduced risk. The risk of RA was increased in women with a history of hyperemesis (RR 1.70; 95% CI 1.06 to 2.54), gestational hypertension (RR 1.49; 95% CI 1.06 to 2.02) or pre-eclampsia (RR 1.42; 95% CI 1.08 to 1.84). CONCLUSIONS: One-child mothers and young parents are at increased risk of RA later in life, possibly due to socioeconomic factors. The novel finding of a significantly increased risk of RA in women whose pregnancies were complicated by hyperemesis, gestational hypertension or pre-eclampsia might reflect reduced immune adaptability to pregnancy in women disposed to RA or a role of fetal microchimerism in the aetiology of RA.

Alcohol consumption is associated with decreased risk of rheumatoid arthritis: results from two Scandinavian case-control studies.

OBJECTIVES: To determine the association between risk of rheumatoid arthritis (RA) and alcohol consumption in combination with smoking and HLA-DRB1 shared epitope (SE). METHODS: Data from two independent case-control studies of RA, the Swedish EIRA (1204 cases and 871 controls) and the Danish CACORA (444 cases and 533 controls), were used to estimate ORs of developing RA for different amounts of alcohol consumed. RESULTS: Alcohol consumption was significantly more common in controls (p<0.05) and dose-dependently associated with reduced risk of RA (p for trend <0.001) in both studies. Among alcohol consumers, the quarter with the highest consumption had a decreased risk of RA of the order of 40-50% compared with the half with the lowest consumption (EIRA, OR = 0.5 (95% CI 0.4 to 0.6); CACORA, OR = 0.6 (95% CI 0.4 to 0.9)). For the subset of RA that is seropositive for antibodies to citrullinated peptide antigens, alcohol consumption reduced the risk most in smokers carrying HLA-DRB1 SE alleles. CONCLUSIONS: The observed inverse association between alcohol intake and risk of RA and the recent demonstration of a preventive effect of alcohol in experimental arthritis indicate that alcohol may protect against RA. This highlights the potential role of lifestyle in determining the risk of developing RA, and emphasises the advice to stop smoking, but not necessarily to abstain from alcohol in order to diminish risk of RA. The evidence of potential RA prevention should prompt additional studies on how this can be achieved.

Cytokines, autoantibodies and viral antibodies in premorbid and postdiagnostic sera from patients with rheumatoid arthritis: case-control study nested in a cohort of Norwegian blood donors.

OBJECTIVE: To assess the timing of changes in cytokines, cytokine-related markers, autoantibodies and viral antibodies in the pathogenesis of rheumatoid arthritis (RA). METHODS: Case-control study nested in a prospective cohort of 31 330 blood donors in Oslo, Norway. Forty-nine donors developed RA up to 23 years after their most recent blood donation. Stored sera from these donors (case sera) and a sex- and age-matched sample of 245 healthy donors (control sera), and postdiagnostic sera from 33 of the 49 RA cases, were analysed for a panel of cytokines and cytokine-related markers, autoantibodies and antibodies against Epstein-Barr virus and parvovirus B19. RESULTS: Cytokines and cytokine-related markers were generally negative in case sera from >5 years before the diagnosis of RA. In the 5-year interval immediately before the diagnosis of RA, more case than control sera were positive (odds ratios >2) for interleukin (IL)-1 alpha, IL-1 beta, IL-1 receptor antagonist, IL-4, IL-10, tumour necrosis factor-alpha and soluble tumour necrosis factor receptor I. In postdiagnostic sera, however, 11 of 16 examined cytokines and cytokine-related markers were statistically significantly elevated compared with control sera. Seropositivity for IgG antibodies against cyclic citrullinated peptides and for IgM and IgA rheumatoid factors were seen in case sera from up to 18 years before the diagnosis of RA. IgG antibodies against Epstein-Barr virus and parvovirus B19 did not differ significantly between case and control sera. CONCLUSIONS: Cytokines and cytokine-related markers appear to be upregulated rather late in RA pathogenesis. In contrast, IgM rheumatoid factor and IgG anti-cyclic citrullinated peptide autoantibodies may precede the diagnosis of RA by up to two decades.

Invasive Methicillin-Resistant Staphylococcus aureus USA500 Strains from the U.S. Emerging Infections Program Constitute Three Geographically Distinct Lineages.

USA500 isolates are clonal complex 8 (CC8) Staphylococcus aureus strains closely related to the prominent community- and hospital-associated USA300 group. Despite being relatively understudied, USA500 strains cause a significant burden of disease and are the third most common methicillin-resistant S. aureus (MRSA) strains identified in the U.S. Emerging Infections Program (EIP) invasive S. aureus surveillance. To better understand the genetic relationships of the strains, we sequenced the genomes of 539 USA500 MRSA isolates from sterile site infections collected through the EIP between 2005 and 2013 in the United States. USA500 isolates fell into three major clades principally separated by their distribution across different U.S. regions. Clade C1 strains, found principally in the Northeast, were associated with multiple IS256 insertion elements in their genomes and higher levels of antibiotic resistance. C2 was associated with Southern states, and E1 was associated with Western states. C1 and C2 strains all shared a frameshift in the gene encoding AdsA surface-attached surface protein. We propose that the term "USA500" should be used for CC8 strains sharing a recent common ancestor with the C1, C2, and E1 strains but not in the USA300 group.IMPORTANCE In this work, we have removed some of the confusion surrounding the use of the name "USA500," placed USA500 strains in the context of the CC8 group, and developed a strategy for assignment to subclades based on genome sequence. Our new phylogeny of USA300/USA500 will be a reference point for understanding the genetic adaptations that have allowed multiple highly virulent clonal strains to emerge from within CC8 over the past 50 years.

Human papillomavirus-associated cancers in patients with human immunodeficiency virus infection and acquired immunodeficiency syndrome.

BACKGROUND: Human papillomavirus (HPV)-associated anogenital malignancies occur frequently in patients with human immunodeficiency virus (HIV) infection and the acquired immunodeficiency syndrome (AIDS). The purpose of our study was to determine if the high frequency of these cancers is due to lifestyle factors associated with both HPV and HIV infections or to immunosuppression following HIV infection. METHODS: We studied invasive and in situ HPV-associated cancers among 309 365 U.S. patients with HIV infection/AIDS (257 605 males and 51 760 females) from 5 years before the date of AIDS onset to 5 years after this date. Sex-, race-, and age-standardized ratios of observed-to-expected cancers served as measures of relative risk (RR). Trend tests were used to evaluate changes in the RRs during the 10 years spanning AIDS onset. All statistical tests were two-sided. RESULTS: All HPV-associated cancers in AIDS patients occurred in statistically significant excess compared with the expected numbers of cancers. For in situ cancers, overall risks were significantly increased for cervical (RR = 4.6; 95% confidence interval [CI] = 4.3-5.0), vulvar/vaginal (RR = 3.9; 95% CI = 2.0-7. 0), anal (in females, RR = 7.8 [95% CI = 0.2-43.6]; in males, RR = 60.1 [95% CI = 49.2-72.7]), and penile (RR = 6.9; 95% CI = 4.2-10.6) cancers, and RRs increased during the 10 years spanning AIDS onset for carcinomas in situ of the cervix (P: for trend <.001), vulva/vagina (P: for trend =.04), and penis (P: for trend =.04). For invasive cancers, overall risks were significantly increased for cervical (RR = 5.4; 95% CI = 3.9-7.2), vulvar/vaginal (RR = 5.8; 95% CI = 3.0-10.2), and anal (RR = 6.8; 95% CI = 2.7-14.0) cancers in females and for anal (RR = 37.9; 95% CI = 33.0-43.4), penile (RR = 3. 7; 95% CI = 2.0-6.2), tonsillar (RR = 2.6; 95% CI = 1.8-3.8), and conjunctival (RR = 14.6; 95% CI = 5.8-30.0) cancers in males. However, RRs for invasive cancers changed little during the 10 years spanning AIDS onset. CONCLUSIONS: HPV-associated malignancies occur at increased rates in persons with HIV/AIDS. Increasing RRs for in situ cancers to and beyond the time of AIDS onset may reflect the gradual loss of control over HPV-infected keratinocytes with advancing immunosuppression. However, the lack of a similar increase for invasive HPV-associated cancers suggests that late-stage cancer invasion is not greatly influenced by immune status.

Tobacco smoking as a risk factor in anal carcinoma: an antiestrogenic mechanism?

BACKGROUND: Human papillomavirus-associated anogenital carcinogenesis depends on poorly defined cofactors. Smoking was recently suggested to increase the risk of anal cancer more in premenopausal women than in postmenopausal women. Thus, we used our population-based anal cancer case-control study in Denmark and Sweden to test this hypothesis. METHODS: Our study included 417 patients (324 women and 93 men) who were diagnosed with anal cancer (84% invasive cancer) from 1991 through 1994; it also included five patients diagnosed in 1995. Two control groups were used: 1) 554 population control subjects (349 women and 205 men) and 2) 534 patients with rectal adenocarcinoma (343 women and 191 men). Odds ratios (ORs), calculated from logistic regression analyses, were used as measures of relative risk. All P values are two-sided. RESULTS: Compared with the risk for lifelong nonsmokers, the risk of anal cancer was high among premenopausal women who currently smoked tobacco (multivariate OR = 5.6; 95% confidence interval [CI] = 2.4-12.7) and increased linearly by 6.7% per pack-year smoked (one pack-year is equivalent to one pack of cigarettes smoked per day for 1 year) (P for trend <.001). Smoking was not statistically significantly associated with anal cancer risk in postmenopausal women or men. Women whose menstrual periods started late were at high risk (multivariate OR = 3.6; 95% CI = 1.8-7.3, for > or = 17 years of age versus < or = 12 years of age; P for trend <.001), and body mass index (weight in kg/[height in m]2) was inversely associated with risk among women (P<.001). CONCLUSIONS: Because the risk of anal cancer associated with smoking was restricted to premenopausal women and because higher risk was associated with late menarche and lean body composition, female sex hormones may be a factor in anal cancer development in women. Since the anal mucosa is an estrogen-sensitive area, we hypothesize an antiestrogenic mechanism of action for smoking in anal carcinogenesis.

Risk of Hodgkin's disease and other cancers after infectious mononucleosis.

BACKGROUND: Infectious mononucleosis, which is caused by the Epstein-Barr virus, has been associated with an increased risk for Hodgkin's disease. Little is known, however, about how infectious mononucleosis affects long-term risk of Hodgkin's disease, how this risk varies with age at infectious mononucleosis diagnosis, or how the risk for Hodgkin's disease varies in different age groups. In addition, the general cancer profile among patients who have had infectious mononucleosis has been sparsely studied. METHODS: Population-based cohorts of infectious mononucleosis patients in Denmark and Sweden were followed for cancer occurrence. The ratio of observed-to-expected numbers of cancers (standardized incidence ratio [SIR]) served as a measure of the relative risk for cancer. SIRs of Hodgkin's disease in different subsets of patients were compared with the use of Poisson regression analysis. All statistical tests including the trend tests were two-sided. RESULTS: A total of 1381 cancers were observed during 689 619 person-years of follow-up among 38 562 infectious mononucleosis patients (SIR = 1. 03; 95% confidence interval [CI] = 0.98-1.09). Apart from Hodgkin's disease (SIR = 2.55; 95% CI = 1.87-3.40; n = 46), only skin cancers (SIR = 1.27; 95% CI = 1.13-1.43; n = 291) occurred in statistically significant excess. In contrast, the SIR for lung cancer was reduced (SIR = 0.71; 95% CI = 0.58-0.86; n = 102). The SIR for Hodgkin's disease remained elevated for up to two decades after the occurrence of infectious mononucleosis but decreased with time since diagnosis of infectious mononucleosis (P: for trend <.001). The SIR for Hodgkin's disease tended to increase with age at diagnosis of infectious mononucleosis (P: for trend =.05). Following infectious mononucleosis, the SIR for Hodgkin's disease at ages 15-34 years was 3.49 (95% CI = 2.46-4.81; n = 37), which was statistically significantly higher than the SIR for any other age group (P: for difference =.001). CONCLUSION: The increased risk of Hodgkin's disease after the occurrence of infectious mononucleosis appears to be a specific phenomenon.

Birth characteristics, sibling patterns, and acute leukemia risk in childhood: a population-based cohort study.

BACKGROUND: The occurrence of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) during childhood may be influenced by factors operating in fetal life. Furthermore, childhood ALL has been suggested to be linked to patterns of infection during infancy. PURPOSE: To explore these hypotheses and other associations, we studied the impact of sibling patterns (e.g., birth order) and birth characteristics (e.g., birth weight) on the risk of childhood ALL and AML. METHODS: By linkage of records of population-based registries, a cohort of all children whose mothers were born in Denmark from April 1935 through March 1978 was established. Children who developed ALL or AML during the period from April 1968 through December 1992 were identified by linkage with the Danish Cancer Registry. Birth weights were obtained for children born during the period from January 1973 through December 1992 by linkage with the Medical Birth Registry. RESULTS: The cohort of approximately 2.0 million children was followed for the diagnosis of ALL or AML for 20.9 million person-years. A total of 704 cases of childhood ALL were identified. Among 0-4 year olds, the relative risks (RRs) of ALL for birth order positions 1, 2, 3, and 4+ were 1.00 (reference), 0.85 (95% confidence interval [CI] = 0.68-1.07), 0.91 (95% CI = 0.66-1.25), and 0.57 (95% CI = 0.30-1.06), respectively (P for trend = .09). A decreasing trend was not observed among 5-14 year olds. A significant log-linear association between birth weight and the risk of ALL was observed for both age groups. Overall, the RR of ALL increased by a factor of 1.46 (95% CI = 1.18-1.81) (P = .0005) for each kilogram of increase in birth weight. A total of 114 cases of childhood AML were identified. Children born second or later in the birth order had an increased risk of AML (RR = 1.53; 95% CI = 1.01-2.32) compared with firstborns. A particularly high risk of AML at ages 2 (RR = 2.53; 95% CI = 1.46-4.40) and 3 years was associated with having siblings compared with being an only child at those ages. Similar to the findings for ALL risk, there was a significant association between birth weight and AML risk. The relative increase in AML risk per 1-kg increase in birth weight was 2.14 (95% CI = 1.19-3.85; P = .009). CONCLUSION AND IMPLICATIONS: The association between birth weight and childhood leukemia suggests the importance of intrauterine factors. A plausible explanation may be that increasing birth weight is associated with a higher rate of cell proliferation and/or a larger number of precursor cells being at risk of malignant transformation. The inverse association between birth order and ALL risk among 0-4 year olds was weak, but it was compatible with the hypothesis that delayed exposure to infection may increase the risk of ALL in this age group. The association of childhood AML with birth order and sibship size at young ages deserves further attention in the search for environmental factors that affect childhood AML risk.

A prospective study showing long-term infection with human papillomavirus 16 before the development of cervical carcinoma in situ.

Human papillomavirus 16 (HPV16) is a predominant cause of cervical neoplasia. However, no population-based study with long-term follow-up has clarified the temporal relationship between HPV16 infection and occurrence of carcinoma in situ, or the importance of recurrent or persistent infection. This nested case-control study was carried out in a population-based cohort of women participating in cytological screening whose initial smear, taken in 1969-1995, was normal. During up to 26 years of follow-up, carcinoma in situ was diagnosed in 484 eligible women. Archival smears from these women were compared with smears from 619 individually matched controls. After DNA extraction, a highly sensitive PCR system was used to detect HPV16. Among case women, the prevalence of HPV16 positivity was 56% at the time of diagnosis. The relative risk of cervical carcinoma in situ increased from 3.6 (95% confidence interval, 1.2-11.0) 13 years before diagnosis to 11.1 (95% confidence interval, 5.5-22.2) 1 year before diagnosis. Having a positive smear at entry to the cohort increased risk >5-fold, whereas having persistent infection with HPV in two subsequent smears increased risk 30-fold. We estimated that among HPV16-positive women, the median incubation period from infection to carcinoma in situ was 7-12 years. We conclude that evidence of persistent and/or recurrent infection is associated with a drastically higher risk of cervical carcinoma in situ than occasional infection with HPV16.

Variants of squamous cell carcinoma of the anal canal and perianal skin and their relation to human papillomaviruses.

High-risk types of human papillomaviruses (hrHPVs) may be a necessary cause in cervical cancer and in some subtype of anal, vulvar, and penile cancers. Large studies aimed at characterizing hrHPV-associated and non-hrHPV-associated subtypes of anal carcinomas are, however, lacking. We searched for human papillomavirus type 16 and 13 other hrHPVs in tumor tissue by PCR and performed a systematic histological evaluation of specimens from 386 patients with anal cancer (86% invasive; 302 women and 84 men). Cancers in women and homosexual men were more often hrHPV positive (P < 0.01) and located in the anal canal (P < or = 0.01) than were cancers in heterosexual men. In both women and men, anal canal cancers contained hrHPV clearly more often than did perianal skin cancers, and increasing hrHPV positivity was seen with higher localization in the anal canal. Indeed, 95 and 83% of cancers involving the anal canal in women and men, respectively, were hrHPV positive versus 80 and 28% of perianal skin cancers (P-trend < 0.001). Basaloid feature, adjacent anal intraepithelial neoplasia, poor or absent keratinization, and a predominance of small or medium neoplastic cells were all strongly positively associated with hrHPV status. Like cancer of the uterine cervix, the development of cancer of the anal canal may require infection with hrHPV, whereas a dual etiology of perianal skin cancers bears parallels to vulvar and penile cancers.

The length of the intact donor chromosome segment around a target gene in marker-assisted backcrossing.

Recurrent backcrossing is an established procedure to transfer target genes from a donor into the genetic background of a recipient genotype. By assessing the parental origin of alleles at markers flanking the target locus one can select individuals with a short intact donor chromosome segment around the target gene and thus reduce the linkage drag. We investigated the probability distribution of the length of the intact donor chromosome segment around the target gene in recurrent backcrossing with selection for heterozygosity at the target locus and homozygosity for the recurrent parent allele at flanking markers for a diploid species. Assuming no interference in crossover formation, we derived the cumulative density function, probability density function, expected value, and variance of the length of the intact chromosome segment for the following cases: (1) backcross generations prior to detection of a recombinant individual between the target gene and the flanking marker; (2) the backcross generation in which for the first time a recombinant individual is detected, which is selected for further backcrossing; and (3) subsequent backcross generations after selection of a recombinant. Examples are given of how these results can be applied to investigate the efficiency of marker-assisted backcrossing for reducing the length of the intact donor chromosome segment around the target gene under various situations relevant in breeding and genetic research.

Processing of histamine-induced itch in the human cerebral cortex: a correlation analysis with dermal reactions.

The subjective sensation of itch is a complex emotional experience depending on a variety of factors. In this study, the central nervous processing of pruritus was investigated in a human model. Activation of involved cerebral areas was correlated to scales of nociception and skin reactions. Six healthy male right-handed subjects participated in a standardized epidermal stimulus model with nine increasing doses of histamine dihydrochloride (0.03%-8%) on their right forearms. Controls consisted of three NaCl stimuli. Cerebral activation patterns were determined by H(2)(15)O positron emission tomography 120 s after stimulation. Dermal reactions to the stimulus (wheal, flare, temperature) were coregistered during the procedure. Itch sensation was determined by visual analog scale rating. Pain was not reported during the study; all volunteers had localized itch from 0.03% histamine on. Subtraction analysis versus control revealed significant activation of the left primary sensory cortex and motor-associated areas (mainly primary motor cortex, supplementary motor area, premotor cortex). Predominantly left-sided activations of frontal, orbitofrontal, and superior temporal cortex and anterior cingulate were also observed. Correlation analysis revealed coactivation of dermal reactions and cerebral response to itch in the following Brodmann areas with a Z score greater than 5: wheal, areas 5 (bilateral) and 19 (right); flare, areas 2-5 (left); temperature, area 10 (left) and left insula. Itch intensity ratings were mainly correlated with activation of the left sensory and motor areas. Functional covariates of the itch sensation in the central nervous system were identified. The intention to pruritofensive movements is probably mirrored by the activation of motor areas in the cortex. Other areas may be involved in emotional processing of sensations. Skin reactions wheal and flare also had significantly activated covariate areas in the central nervous system.J Invest Dermatol 115:1029-1033 2000