Hyperemesis gravidarum and long-term mortality: a population-based cohort study

OBJECTIVE

To investigate whether exposure to hyperemesis gravidarum (HG) is associated with increased maternal long-term mortality.

DESIGN

Population-based cohort study.

SETTING

Medical Birth Registry of Norway (1967-2002) linked to the Cause of Death Registry.

POPULATION

Women in Norway with singleton births in the period 1967-2002, with and without HG. Women were followed until 2009 or death.

METHODS

Cox proportional hazard regression model was applied to estimate hazard ratios (HRs) with 95% confidence interval (CI).

MAIN OUTCOME MEASURES

The primary outcome was all-cause mortality during follow up. Secondary outcomes were cause-specific mortality (cardiovascular mortality, deaths due to cancer, external causes or mental and behavioural disorders).

RESULTS

Of 999 161 women with singleton births, 13 397 (1.3%) experienced HG. During a median follow up of 26 years (25 902 036 person-years), 43 470 women died (4.4%). Women exposed to HG had a lower risk of long-term all-cause mortality compared with women without HG (crude HR 0.82; 95% CI 0.75-0.90). When adjusting for confounders, this reduction was no longer significant (adjusted HR 0.92; 95% CI 0.84-1.01). Women exposed to HG had a similar risk of cardiovascular death as women not exposed (adjusted HR 1.04; 95% CI 0.83-1.29), but a lower long-term risk of death from cancer (adjusted HR 0.86; 95% CI 0.75-0.98).

CONCLUSION

In this large population-based cohort study, HG was not associated with an increased risk of long-term all-cause mortality. Women exposed to HG had no increase in mortality due to cardiovascular disease, but had a reduced risk of death from cancer.

TWEETABLE ABSTRACT

Population-based cohort study: Hyperemesis was not associated with an increased risk of long-term mortality.

Profiling of the small RNA populations in human testicular germ cell tumors shows global loss of piRNAs

Background

Small non-coding RNAs play essential roles in gene regulation, however, the interplay between RNA groups, their expression levels and deregulations in tumorigenesis requires additional exploration. In particular, a comprehensive analysis of microRNA (miRNA), PIWI-interacting RNAs (piRNAs), and tRNA-derived small RNAs in human testis and testicular germ cell tumor (TGCT) is lacking.

Results

We performed small RNA sequencing on 22 human TGCT samples from 5 histological subtypes, 3 carcinoma in situ, and 12 normal testis samples. miRNA was the most common group among the sequences 18–24 nt in length and showed histology-specific expression. In normal samples, most sequences 25–31 nucleotides in length displayed piRNA characteristics, whereas a large proportion of the sequences 32–36 nt length was derived from tRNAs. Expression analyses of the piRNA population demonstrated global loss in all TGCT subtypes compared to normal testis. In addition, three 5′ small tRNA fragments and 23 miRNAs showed significant (p < 10⁻⁶) differential expression in cancer vs normal samples.

Conclusions

We have documented significant changes in the small RNA populations in normal adult testicular tissue and TGCT samples. Although components of the same pathways might be involved in miRNA, piRNA and tRNA-derived small RNA biogenesis, our results showed that the response to the carcinogenic process differs between these pathways, suggesting independent regulation of their biogenesis. Overall, the small RNA deregulation in TGCT provides new insight into the small RNA interplay.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0411-4) contains supplementary material, which is available to authorized users.

Genetic variation in AKT1, PTEN and the 8q24 locus, and the risk of testicular germ cell tumor

STUDY QUESTION

Is there an association between testicular germ cell tumor (TGCT) and genetic polymorphisms in AKT1, PTEN and the 8q24 locus?

SUMMARY ANSWER

Our findings suggest that genetic variation in PTEN may influence the risk of TGCT.

WHAT IS KNOWN ALREADY

There is strong evidence that genetic variation influences the risk of TGCT. The oncogene, AKT1, the tumor suppressor gene, PTEN and the chromosome 8q24 locus play important roles in cancer development in general.

STUDY DESIGN, SIZE, DURATION

We have conducted a population-based Norwegian-Swedish case-parent study, based on cases diagnosed in 1990-2008, including 831 triads (TGCT case and both parents), 474 dyads (TGCT case and one parent) and 712 singletons (only the TGCT case). In addition we expanded the study to include 3922 unrelated male controls from the TwinGene project.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We genotyped 26 single nucleotide polymorphisms (SNPs) in AKT1, PTEN and the 8q24 locus. First, triads and dyads were included in a likelihood-based association test. To increase the statistical power, case singletons and controls from the TwinGene project were included in a single test for association. We examined if the allelic effect on TGCT risk differed by histological subgroup, country of origin or parent of origin. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated with Bonferroni correction (P bonf) for multiple testing.

MAIN RESULTS AND THE ROLE OF CHANCE

In the case-parent analyses, none of the 26 SNPs were significantly associated with TGCT. Of the 23 SNPs investigated in the combined study, one SNP in PTEN (rs11202586) remained associated with TGCT risk after adjusting for multiple testing (OR = 1.16, 95% CI = 1.06-1.28, P bonf = 0.040). We found no difference in risk according to histological subgroup, parent of origin or between countries.

LIMITATIONS, REASONS FOR CAUTION

Our study is strengthened by the population-based design and large sample size, which gives high power to detect risk alleles. The reported association was not highly significant, and although it was based on an a priori hypothesis of this tumor suppressor gene being implicated in the etiology of TGCT, replication studies, as well as functional studies of this polymorphism, are warranted.

WIDER IMPLICATIONS OF THE FINDINGS

We report, to our knowledge, a novel association between TGCT and a marker in the tumor suppressor gene PTEN. Previous studies have linked PTEN to TGCT etiology, and there is also a link between PTEN and KITLG, which contains TGCT susceptibility loci revealed through recent genome-wide studies.

Perinatal characteristics and breast cancer risk in daughters: a Scandinavian population-based study

The in utero origins of breast cancer are an increasing focus of research. However, the long time period between exposure and disease diagnosis, and the lack of standardized perinatal data collection makes this research challenging. We assessed perinatal factors, as proxies for in utero exposures, and breast cancer risk using pooled, population-based birth and cancer registry data. Birth registries provided information on perinatal exposures. Cases were females born in Norway, Sweden or Denmark who were subsequently diagnosed with primary, invasive breast cancer (n = 1419). Ten controls for each case were selected from the birth registries matched on country and birth year (n = 14,190). Relative risks (RRs) and 95% confidence intervals (CIs) were estimated using unconditional regression models. Breast cancer risk rose 7% (95% CI 2-13%) with every 500 g (roughly 1 s.d.) increase in birth weight and 7% for every 1 s.d. increase in birth length (95% CI 1-14%). The association with birth length was attenuated after adjustment for birth weight, while the increase in risk with birth weight remained with adjustment for birth length. Ponderal index and small- and large-for-gestational-age status were not better predictors of risk than either weight or length alone. Risk was not associated with maternal education or age, gestational duration, delivery type or birth order, or with several pregnancy complications, including preeclampsia. These data confirm the positive association between birth weight and breast cancer risk. Other pregnancy characteristics, including complications such as preeclampsia, do not appear to be involved in later breast carcinogenesis in young women.

IFPA Meeting 2011 workshop report I: Placenta: Predicting future health; roles of lipids in the growth and development of feto-placental unit; placental nutrient sensing; placental research to solve clinical problems--a translational approach

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2011 there were twelve themed workshops, four of which are summarized in this report. These workshops related to both basic science and clinical research into placental growth and nutrient sensing and were divided into 1) placenta: predicting future health; 2) roles of lipids in the growth and development of feto-placental unit; 3) placental nutrient sensing; 4) placental research to solve clinical problems: a translational approach.

Breed differences in the proportional morbidity of testicular tumours and distribution of histopathologic types in a population-based canine cancer registry

Histologically verified tumours submitted to the Norwegian Canine Cancer Register from 1990 to 1998 were studied (n=14,401). The proportion of testicular tumours (n=345) was 2.4%, and the breakdown of histological tumour diagnoses is presented. The frequency of the most common histopathological types was 33% interstitial (Leydig), 26.4% Sertoli and 33.9% seminomas/germ cell tumours. The average age at diagnosis was 10 years, but was significantly lower for Sertoli cell tumours (8.6 years) than for the other tumour types. Following a histopathological re-evaluation, 22.5% of the original tumor diagnoses were modified. Proportional morbidity ratios were calculated and individuals from the breeds Shetland sheepdog and Collie were five times more likely to have testicular tumours than the overall average for the registry. Breed differences in the distribution of histopathologic types were observed. Shetland sheepdog and Collie were most commonly diagnosed with Sertoli cell tumours, while all tumours from Norwegian elkhound in this material were seminomas.

Conditions in utero and cancer risk

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Risk factors for testicular cancer – differences between pure non-seminoma and mixed seminoma/non-seminoma?

The origin of testicular germ cell cancer (TGCC) is believed to be carcinoma in situ cells developed in utero. Clinically, TGCCs are divided into two major histological groups, seminomas and non-seminomas, where the latter group includes non-seminomatous TGCCs with seminomatous components (mixed S/NS TGCC). Recent studies, however, have suggested that non-seminomas and mixed S/NS TGCCs could have certain differences in aetiology, and in this study the TGCCs were divided into three, rather than the conventional two histological groups. A large case-control study was undertaken on data on all live-born boys registered in the Medical Birth Registry of Norway during the period 1967-1998 (n=961 396). Among these were 1087 TGCC cases registered in the Cancer Registry of Norway until February 2004. We found several risk factors for TGCC, including low parity, low gestational age, epilepsy and retained placenta. Several of the variables studied seemed to be risk factors for specific histological groups, e.g. parity 0 vs. 2 and low gestational age being associated with increased risk of non-seminomas, but not of mixed S/NS TGCC, and low maternal age being associated with increased risk of mixed S/NS TGCC, but not of non-seminomatous TGCC. Therefore, our results might suggest that non-seminomas and mixed S/NS TGCCs have partially different risk factors, whose associations may be obscured by combining these two histological groups. The histological groups were not significantly different, however. Most of our findings on risk factors for TGCC are in agreement with at least some previous studies. An unexplainable exception is low birth weight being associated with reduced risk of TGCC in our study.

Biopsy of colorectal polyps is not adequate for grading of neoplasia

BACKGROUND AND STUDY AIM

Valid tissue sampling of colorectal adenomas is crucial for their management in terms of treatment and follow-up. The aim of this study was to assess the validity of a cold biopsy sample as representative for the whole polypectomy specimen, with regard to histopathological features.

PATIENTS AND METHODS

As part of the Norwegian Colorectal Cancer Prevention trial, 442 participants (60% men) who fulfilled the criterion of colonoscopic recovery of adenoma that had been biopsied at flexible sigmoidoscopy, had their adenomas subsequently removed by polypectomy (snare resection) at colonoscopy. Logistic regression analysis was used to determine which variables contributed to the histopathological discrepancy between cold biopsy and polypectomy specimens.

RESULTS

Among the 532 colorectal adenomas biopsied at flexible sigmoidoscopy and removed by colonoscopy, the assessment of intraepithelial neoplasia (dysplasia) status was changed in 51 adenomas (10%), and 38 (7%) of them had been underestimated at biopsy compared with polypectomy. Likewise, the assessment of villousness was changed in 45 adenomas (9%), being upgraded in 26 (6%) at polypectomy compared with biopsy. In a multivariate model, the diameter of neoplasia at polypectomy was positively associated with increased risk of the underestimation of intraepithelial neoplasia and/or villousness influencing a diagnosis of advanced colorectal neoplasia, when cold biopsy and polypectomy specimens were compared ( Ptrend=0.01). Among 56 cases of advanced neoplasia, 35 (63%) showed only low-grade intraepithelial neoplasia on biopsy.

CONCLUSIONS

Biopsy-based diagnosis underestimated histopathological diagnosis in about 10% of colorectal adenomas detected by flexible sigmoidoscopy screening, but advanced neoplasia was underestimated in more than 60%. Efforts must be made to obtain polypectomy specimens to secure precise diagnosis.

Lifestyle-related risk factors and chemoprevention for colorectal neoplasia: experience from the large-scale NORCCAP screening trial

The objective of this study was to evaluate the potential beneficial effects of non-steroidal anti-inflammatory drugs (NSAIDs) and/or acetylsalicylic acid (ASA) and hormone replacement therapy (HRT) on colorectal neoplasia, and to compare their effects with those of lifestyle-related risk factors in 12 960 individuals who underwent flexible sigmoidoscopy screening examination. The association between these factors and colonic neoplasia was assessed by logistic regression analysis. NSAIDs and/or ASA intake were associated with decreased risk of distal low grade adenoma (DLGA) (adjusted odds ratio (OR) 0.80, P trend=0.02) in men. The duration of HRT was inversely related to the risk of DLGA (OR 0.89, P trend=0.08). Current smoking increased the risk of DLGA and distal advanced neoplasia (DAN) in both men (OR 2.50, P<0.01) and women (OR 2.30, P<0.01). There was a significant positive trend for increasing risk of DLGA (OR 1.16, P<0.01) and DAN (OR 1.20, P=0.02) with increasing use of alcohol among men, but not among women. Prescription of NSAIDs and/or ASA for chronic conditions may not be expected to have a substantial preventive effect on colorectal neoplasia in comparison with the adverse effect of smoking and alcohol. This may be explained by an increased risk of colorectal neoplasia for patients with conditions for which NSAIDs or ASA are being prescribed.

Early life events and later risk of colorectal cancer: age-period-cohort modelling in the Nordic countries and Estonia

BACKGROUND

A lowering of colorectal cancer risk for the birth cohorts born around World War II (WWII) has previously been observed in Norway, a country which suffered some 20% caloric restriction during the war. The purpose of the study was to conduct a similar kind of analysis in the other Nordic countries and Estonia, which were also subjected to various degrees of energy restriction during WWII.

METHODS

All new cases of colorectal cancer in the Nordic countries and Estonia diagnosed between 40 and 84 years of age and born between 1874 and 1953, were collected from the national cancer registries. The incidence data were fitted to an age-period-cohort model.

RESULTS

A transient drop in the estimated colorectal cancer incidence rate was observed for the birth cohorts born around WWII in Estonia, together with a tendency of decreased risk in Sweden and Denmark.

CONCLUSION

The previously observed lowering of colorectal cancer risk for persons born during WWII in Norway also prevails in Estonia. Energy restriction is a possible explanation for these findings, since the countries suffered from varying nutritional conditions during the war. Exogenous factors acting during periods early in life may have an impact on later colorectal cancer risk.

The association between nutritional conditions during World War II and childhood anthropometric variables in the Nordic countries

BACKGROUND

The purpose of the study was to examine the height and weight in Nordic children during the years around World War II (WWII), and compare them with the nutritional situation during the same period.

METHODS

Information on food consumption and energy intake were obtained from the literature. Anthropometric data were collected from the Nordic capitals and cover the period from 1930 to 1960 for ages 7-13 years.

RESULTS

The greatest energy restriction took place in Norway (20%), followed by Finland (17%), while Sweden and Denmark had a restriction of 4-7% compared to pre-war levels. The most pronounced effect of WWII on height and weight is seen in Norwegian children, while some effect is observed for the youngest children in Finland. Little or no effect is seen in Sweden and Denmark.

CONCLUSION

The Nordic children were affected by WWII in terms of a transient reduction in temporal trends in height and weight, and the magnitude of this decrease was associated with the severity of the energy restriction prevailing in the respective country during the war. These findings warrant further studies of the chronic diseases associated with height and weight for cohorts being in their growth periods during WWII.

Differential distribution of splice variants of estrogen receptor beta in human testicular cells suggests specific functions in spermatogenesis

A growing number of estrogen receptor beta (ER beta) splice variants are reported. Several of these have been discovered in testis, but with few exceptions little is known about their cellular localization. The aim of this study was to identify and elucidate the mRNA expression pattern of the different ER beta splice variants in human testicular cells. Northern analysis was performed on whole testis and fractions enriched in germ cells from untreated men and from estrogen-treated men undergoing sex change surgery. Probes were constructed in order to systematically screen for and identify various ER beta splice variants. Several ER beta bands were observed in the human testis, in which splice variants constituted the major part of total ER beta transcripts. Interestingly, only two ER beta wild-type transcripts were detected. These seem to be virtually absent from the haploid germ cells and are probably mainly located in somatic cells and/or primary spermatocytes. Several novel ER beta deletion variants were found in high levels in the haploid germ cell fractions and were nearly absent in testicular cells from the estrogen-treated men. The cell-dependent distribution raises the question whether splice variants may have specific functions in spermatogenesis, and whether the differential splicing of ER beta is regulated in a cell-specific manner.

Testing for faecal calprotectin (PhiCal) in the Norwegian Colorectal Cancer Prevention trial on flexible sigmoidoscopy screening: comparison with an immunochemical test for occult blood (FlexSure OBT)

BACKGROUND

Screening for colorectal cancer (CRC) using guaiac based faecal occult blood tests (FOBT) has an estimated programme sensitivity of >60% but <30% for strictly asymptomatic CRC in a single screening round. In search for improved non-invasive tests for screening, we compared a test for faecal calprotectin (PhiCal) with a human haemoglobin immunochemical FOBT (FlexSure OBT).

METHODS

In the Norwegian Colorectal Cancer Prevention (NORCCAP) trial, screenees in one screening arm were offered screening with combined flexible sigmoidoscopy (FS) and FlexSure OBT. They were also requested to bring a fresh frozen sample of stool for the PhiCal test which was performed on samples from screenees with CRC (n = 16), high risk adenoma (n = 195), low risk adenoma (n = 592), and no adenoma (n = 1518) (2321 screenees in total). A positive PhiCal test was defined by a calprotectin level > or =50 microg/g.

RESULTS

The PhiCal test was positive in 24-27% of screenees whether they had no adenoma, low risk adenoma, or high risk adenoma. Ten (63%) of 16 CRCs gave a positive PhiCal test. The total positivity rate in this population was 25% for the PhiCal test compared with 12% for FlexSure OBT, with a sensitivity for advanced neoplasia of 27% and 35%, respectively. Specificity for "any neoplasia" was 76% for the PhiCal test and 90% for FlexSure OBT.

CONCLUSIONS

In colorectal screening, the performance of the PhiCal test on a single spot from one stool sample was poorer than a single screening round with FlexSure OBT and cannot be recommended for population screening purposes. The findings indicate a place for FlexSure OBT in FOBT screening.

Colorectal cancer survival trends in Norway 1958–1997

The purpose of this study was to examine the pattern of survival for colorectal adenocarcinoma (CRC), and to investigate the prognostic factors for the disease. In the analysis, 50993 cases of CRC aged 40-84 years, diagnosed between 1958 and 1997 in Norway, were included. Esteve's relative survival method was used, together with a time trend analysis, conducted by least-squares linear regression. Cox proportional hazards regression analysis was used to examine cause-specific mortality. Five-year relative CRC survival has increased by an estimated 3% per 5-year diagnostic period. In 1958-1962, relative survival was about 40% for both males and females, and increased to 56 and 60%, respectively, in 1993-1997. Rectal cancer had a higher cause-specific mortality (RR 1.26, 95% CI 1.22-1.30) than proximal colon (reference) and distal colon (RR 0.97, 95% CI 0.93-1.00 cancers), while females had a lower cause-specific mortality than males (RR 0.88, 95% CI 0.86-0.90). The increase in the relative survival rate in Norway is probably due to improved treatments and advanced diagnostics. Norway has a higher CRC survival rate than the EUROCARE average.

Inter-endoscopist variation in polyp and neoplasia pick-up rates in flexible sigmoidoscopy screening for colorectal cancer

BACKGROUND

The Norwegian Colorectal Cancer Prevention study is an ongoing flexible sigmoidoscopy (FS) screening trial for colorectal cancer. Twenty-one thousand average-risk individuals, aged 50-64 years, living in two separate areas in Norway were randomly drawn from the Population Registry and invited to once-only screening flexible sigmoidoscopy. Examinations were performed over 3 years, at 2 centres, by 8 different endoscopists, using the same type of equipment. The aim of the present study was to investigate possible differences between endoscopists in detecting individuals with polyps, adenomas and advanced lesions (adenomas with severe dysplasia and/or villous components and/or size larger than 9 mm and carcinoma) in flexible sigmoidoscopy screening.

METHODS

The present trial comprises data from 8822 individuals, aged 55-64 years, who have undergone a flexible sigmoidoscopy. In the study period, all lesions detected by the different endoscopists were registered. Tissue samples were taken from all lesions detected.

RESULTS

Detection rates varied significantly between endoscopists, ranging from 36.4% to 65.5% for individuals with any polyp, from 12.7% to 21.2% for any adenoma and from 2.9% to 5.0% for advanced lesions. In a multiple logistic regression model, the performing endoscopist was a strong independent predictor for detection of individuals with polyps (P < 0.001 ), adenomas (P < 0.001) and advanced lesions (P = 0.01).

CONCLUSION

Detection rates for colorectal lesions vary significantly between endoscopists in colorectal cancer screening. Establishing systems for monitoring performance in screening programmes is important. Supervised training and re-certification for endoscopists with poor performance should be considered.

The Norwegian Colorectal Cancer Prevention (NORCCAP) screening study: baseline findings and implementations for clinical work-up in age groups 50-64 years

BACKGROUND

Randomized controlled trials of sufficient power testing the long-term effect of screening for colorectal neoplasia only exist for faecal occult blood testing (FOBT). There is indirect evidence that flexible sigmoidoscopy (FS) may have a greater yield. The aim of this study was to determine the diagnostic yield of screening with FS or a combination of FS and FOBT in an average-risk population in an urban and combined urban and rural population in Norway.

METHODS

20,780 men and women (1:1), aged 50-64 years, were invited for once-only screening (FS only or a combination of FS and FOBT (1:1)) by randomization from the population registry. A positive FS was defined as a finding of any neoplasia or any polyp > or = 10 mm. A positive FS or FOBT qualified for colonoscopy.

RESULTS

Overall attendance was 65%. Forty-one (0.3%) cases of CRC were detected. Any adenoma was found in 2208 (17%) participants and 545 (4.2%) had high-risk adenomas. There was no difference in diagnostic yield between the FS and the FS and FOBT group regarding CRC or high-risk adenoma. Work-up load comprised 2821 colonoscopies in 2524 (20%) screenees and 10% of screenees were recommended later colonoscopy surveillance. There were no severe complications at FS, but six perforations after therapeutic colonoscopy (1:336).

CONCLUSIONS

The present study bodes well for future management of a national screening programme, provided that follow-up results reflect adequate proof of a net benefit. It is highly questionable whether the addition of once-only FOBT to FS will contribute to this effect.

Grading of distal colorectal adenomas as predictors for proximal colonic neoplasia and choice of endoscope in population screening: experience from the Norwegian Colorectal Cancer Prevention study (NORCCAP)

BACKGROUND AND AIMS

The purpose of this study was to evaluate the utility of easily measured clinical variables at flexible sigmoidoscopy (FS) screening that might predict a proximal advanced neoplasm (PAN).

METHODS

We studied 1833 subjects with biopsy verified adenomas at FS who subsequently underwent full colonoscopy.

RESULTS

A total of 387 (21%) subjects had proximal colonic neoplasms (PCN) and 85 (5%) had PAN. In univariate comparison, the risk of PAN increased more than threefold in the presence of a distal adenoma measuring either > or =10 mm in diameter or containing villous components. Multiplicity of distal adenomas, severe dysplasia, or age > or =60 years increased the risk of PAN more than twofold. In the multivariate model, the presence of a distal adenoma > or =10 mm, villousness, and multiplicity maintained their significance as predictive variables for increased risk of proximal neoplasms, whereas sex and severe dysplasia lost their significance. By recommending colonoscopy only to individuals with multiple (>1) adenomas or any high risk adenoma at FS, we would have reduced the number of colonoscopies by 1209 (66%) but would have missed 32 (38%) participants with PAN and 217 (56%) with PCN. By using a 60 cm endoscope instead of an ordinary colonoscope at FS, nine (2%) participants with advanced neoplasms, including three patients with cancer, would have been missed.

CONCLUSION

The present study supports the concept of defining "any adenoma" as a positive FS, qualifying for colonoscopy. We recommend the use of an ordinary colonoscope instead of a 60 cm sigmoidoscope for FS screening examinations.

Use of a disposable sheath system for flexible sigmoidoscopy in decentralized colorectal cancer screening

BACKGROUND AND STUDY AIMS

To prevent transmission of infectious agents and to reduce instrument reprocessing time, the use of disposable sheath systems instead of conventionally reprocessed endoscopes has been promoted for flexible sigmoidoscopy. This trial primarily investigated the feasibility of a disposable sheath system for flexible sigmoidoscopy in decentralized colorectal cancer screening.

PATIENTS AND METHODS

In an ongoing colorectal cancer screening trial, 226 consecutive participants were randomly allocated to have their flexible sigmoidoscopy performed with either a fiberoptic sigmoidoscope covered with a disposable sheath ("EndoSheath group") or a conventional video colonoscope ("standard colonoscope group"). All examinations were performed at a temporary screening center. The patients' experience was documented using a questionnaire. The feasibility of running temporary screening units was evaluated.

RESULTS

Examinations beyond the 60-cm level were excluded. Thus, 113 patients (examined with the disposable instrument) and 87 (standard instrument) were eligible for analysis. When the sheathed system was used, all the devices needed could be satisfactorily transported. A screening center could be set up within a few hours. No differences were observed in patient discomfort. Fewer patients with polyps were observed in the EndoSheath group (48 [42%]), compared with 55 (63%) in the standard colonoscope group; P = 0.005). No significant differences were observed for polyps larger than 5 mm (14 [12%] in the EndoSheath group, 13 [15%] in the standard colonoscope group; P = 0.6).

CONCLUSIONS

Using the disposable system, decentralized colorectal cancer screening was easily established. However, fewer polyps were found, possibly due to the fiberoptic nature of the instrument. Sheathed video instruments are desirable and may increase the diagnostic yield.

Trends in colorectal cancer incidence in Norway by gender and anatomic site: an age-period-cohort analysis

The purpose of this study was to examine the secular trend of colorectal cancer in Norway by gender and subsite. All new cases of cancer in proximal colon, distal colon and rectum diagnosed between 1958 and 1997 in Norway were included in the study, altogether 34 202 and 34 097 cases for men and women, respectively. The incidence data were fitted separately for each gender and subsite to an age-period-cohort model. An increase in incidence of colorectal cancer was seen from 1958 to 1997 for both men and women, although a moderate attenuation of the increase has taken place in the last 15-20 years. This observation is most pronounced for cancer of the distal colon, but is also evident for proximal colonic and rectal cancers. For the distal colon and rectum, the period effect is more important than the cohort effect for both genders, whilst opposite for the proximal colon. The main estimated trend for cohort effects is a steady increase for both men and women, apart from an unexpected drop in incidence among the cohorts born during or shortly after World War II. These findings indicate that different aetiological risk factors may act on cancers of the proximal and distal part of the large bowel and further suggest that exogenous risk factors acting very early in life may play a more important role for colorectal cancer than previously recognized.

Carbon dioxide insufflation reduces discomfort due to flexible sigmoidoscopy in colorectal cancer screening

BACKGROUND

Flexible sigmoidoscopy is currently recommended as a screening modality for colorectal cancer. However, a substantial number of patients experience discomfort because of the procedure. possibly limiting compliance and thus screening success. During endoscopy, air is commonly used to insufflate the bowel. Carbon dioxide rather than air insufflation has been shown to reduce procedure-related pain and discomfort in colonoscopy. The aim of the present study was to evaluate whether carbon dioxide insufflation reduces discomfort during and after flexible sigmoidoscopy for colorectal cancer screening.

METHODS

In a randomized, double-blinded design, 230 consecutive participants in a population-based flexible sigmoidoscopy colorectal cancer screening trial were assigned to have their examination performed with either carbon dioxide or air insufflation. Patients were asked to grade discomfort experienced both during and in the hours after the procedure on a visual analogue scale.

RESULTS

Carbon dioxide insufflation significantly reduced the amount of discomfort at 1, 3 and 6 h after the sigmoidoscopy. One hour after the examination. 84% of patients in the CO2 group reported no discomfort, compared to 64% in the air group (P = 0.006). No differences between the groups were observed during the examination.

CONCLUSIONS

Carbon dioxide insufflation significantly reduced post-examination discomfort. The use of carbon dioxide rather than air insufflation may contribute to better public acceptance for flexible sigmoidoscopy screening.

Continuous evaluation of patient satisfaction in endoscopy centres

BACKGROUND

A randomized sample of 14,000 men and women, aged 55-64 years, resident in the City of Oslo and Telemark County, were drawn from the population registry to be offered a flexible sigmoidoscopy (FS) screening examination. A questionnaire was designed to modify routines and evaluate patient satisfaction.

METHODS

Consecutive participants (4956) were given a questionnaire immediately after the FS to be filled in and returned by mail on the following day. Participants were asked questions about service, practical issues, and the level of pain during the FS and post-examination discomfort. They were also encouraged to give their comments in free text.

RESULTS

Questionnaire replies were received from 4574 (92%) out of 4956 participants. The vast majority reported to have experienced no (70%) or slight (21%) pain during the examination. Women reported pain and post-examination discomfort more often than men. Pain was also associated with age of the patient and length of bowel examined, but not with total examination time. The proportion of painless examinations varied between endoscopists from 62% to 81%. For all endoscopists collectively, this improved during the study period, irrespective of past experience, but trainees seemed to adopt the score of their masters.

CONCLUSIONS

The study demonstrated that the use of feedback information in an endoscopy screening unit may be useful in improving standards, including the performance of endoscopists. It is possible that the introduction of similar feedback systems in routine endoscopy laboratories may in the long run improve the reputation of gastrointestinal endoscopy.

Design, organization and management of a controlled population screening study for detection of colorectal neoplasia: attendance rates in the NORCCAP study (Norwegian Colorectal Cancer Prevention)

BACKGROUND

In the past three decades, the incidence of colorectal cancer (CRC) in Norway has doubled, surpassing all other Nordic countries for both men and women to become the most frequently diagnosed cancer. A small-scale, randomized study on flexible sigmoidoscopy (FS) screening in Telemark, Norway, has shown a reduction in accumulated CRC incidence after 13 years. The aim of our study was to evaluate the effect on CRC mortality and morbidity by screen detection of CRC and removal of precursor lesions (polypectomy), and to test out the management and organization mimicking a countrywide screening service. A total of 13,823 men and women (1:1), age 55-64 years, were drawn randomly from the population registries in Oslo (urban) and the county of Telemark (mixed urban and rural) and invited to have a screening examination. The rest of the relevant age cohorts constituted the control groups. In the screening group, 535 individuals were excluded according to exclusion criteria, rendering 13,288 individuals eligible for screening examination.

METHODS

A once only screening model was used. In the screening group, individuals were randomized to have a once only FS or a combination of FS and faecal occult blood test (FOBT).

RESULTS

The overall attendance rate was 8,849 out of 13,288 (67%); 73% in Telemark and 60% in Oslo. Attendance for FS only was 68% and 65% for combined FS&FOBT.

CONCLUSIONS

The present FSIFS&FOBT screening study obtained a high acceptance rate for both screening modalities. The attendance rate was stable throughout the trial, suggesting an acceptable model for management of future countrywide screening.

NORCCAP (Norwegian colorectal cancer prevention): a randomised trial to assess the safety and efficacy of carbon dioxide versus air insufflation in colonoscopy

BACKGROUND

To eliminate the risk of combustion during electrosurgical procedures and to reduce patient discomfort, carbon dioxide (CO2) insufflation has been recommended during colonoscopy. However, air insufflation is still the standard method, perhaps due to the lack of suitable equipment and shortage of randomised studies.

AIMS

This randomised controlled trial was conducted to assess patient tolerance and safety when using CO2 insufflation during colonoscopy.

PATIENTS

Over an eight month period a successive series of patients referred for a baseline colonoscopy due to findings in a flexible sigmoidoscopy screening trial were randomly assigned to the use of either air or CO2 insufflation during colonoscopy.

METHODS

End tidal CO2 (ETCO2), a non-invasive parameter of arterial pCO2, was registered before and repeatedly during and after the examination. The patient's experience of pain during and after the examination was registered using a visual analogue scale (VAS). Sedation was not used routinely.

RESULTS

CO2 insufflation was used in 121 patients (51%) and air in 119 patients (49%). The groups were similar in age, sex, and caecal intubation rate. No rise in ETCO2 was registered. There were statistically significant differences in VAS scores between the groups with less pain reported when using CO2.

CONCLUSIONS

This randomised study of unsedated patients shows that CO2 insufflation is safe during colonoscopy with no rise in ETCO2 level. CO2 was found to be superior to air in terms of pain experienced after the examination.

Placental transfer of the estrogenic mycotoxin zearalenone in rats

In order to study the possible placental transfer of the Fusarium mycotoxin zearalenone (ZON), Sprague Dawley rats were treated with a single dose (0.74 mg/kg b.w.) of ZON i.v. on day 12 or day 18 of pregnancy, or intragastrically (i.g.) on day 18 of pregnancy. Samples of placenta, foetus, and maternal liver and spleen were collected for chemical analyses 0.3 h after treatment on day 12, and 0.3, 4, and 24 h after treatment on day 18. Three rats were used for each pregnancy day, administration route, and exposure time. The concentrations of ZON and its metabolites alpha- and beta-zearalenol (-ZOL) were determined quantitatively by high-performance liquid chromatography (HPLC) after incubation with beta-glucuronidase and purification on immunoaffinity columns. Tissue distribution was studied by means of whole body autoradiography at 4 and 24 h after treatment with tritiated ZON (750 microCi/kg b.w; 7.4 mg/kg b.w.) on day 18 of pregnancy. ZON and alpha-ZOL were transferred into the foetus on both gestational days. However, a delay in distribution into the foetus, relative to the maternal tissue, was observed. Beta-ZOL was below the detection limit in the foetus. No specific site of foetal accumulation of ZON or its metabolites was apparent. In the maternal tissues, the highest levels of ZON and of alpha- and beta-ZOL were found in the liver.

Do undesirable effects of screening affect all-cause mortality in flexible sigmoidoscopy programmes? Experience from the Telemark Polyp Study 1983-1996

There is substantial evidence for the beneficial effect of screening programmes aimed at reducing mortality from colorectal cancer (CRC). The effect on all-cause mortality, however, may not necessarily be beneficial. In the present study we used the follow-up results 13 years after a flexible sigmoidoscopy screening to evaluate the long-term effects of informing participants about findings at flexible sigmoidoscopy (FS) screening. There were no severe complications and there was no long-term difference in deaths related to whether there had been any mucosal rupture (biopsy or snare resection) or not. As a group, those who attended in 1983 and were informed that they had polyps tended to improve their smoking habits more than those informed that they had no polyps. Similarly, and in spite of more people giving up smoking, the group with polyps had a trend towards a smaller increase in BMI (+0.7 (95% CI 0.2-1.1)) than the polyp-free group (+1.2 (95% CI 0.9-1.6)) (P = 0.07). The observations suggest that flexible sigmoidoscopy screening may face an educational challenge to avoid unfavourable changes in the lifestyle of screenees, an effect that may more than outweigh the beneficial effect of screening.

Reproductive function in male rats after brief in utero exposure to diethylstilboestrol

Long-term effects of brief in utero exposure to diethylstilboestrol (DES) during a foetal period known to be critical for gonadal development were evaluated. Rats were exposed to DES (100 microg/kg body-weight) from day 17 to 19 of pregnancy. All of the DES-treated pregnant rats (11/11) ate parts or whole of their offspring during the first day after birth (p=0.03). Surviving male offspring were examined on day 63 post-partum. DES induced a reduction in weight of the testis (p=0.06) and ventral prostate (p=0.07), even after this short exposure. DES tended to reduce the number of Sertoli cells (p=0.13). Our findings indicate that even a short in utero exposure of rats to DES during a critical period for gonadal development results in cannibalism and reduced testis and ventral prostate weight.

Fish model for assessing the in vivo estrogenic potency of the mycotoxin zearalenone and its metabolites

The in vivo estrogenic potency of zearalenone (ZEA), a mycotoxin produced by different strains of Fusarium fungi, and its metabolites (alpha- and beta-zearalenol), have been studied in fish. Estrogenicity was evaluated using an in vitro competitive receptor binding assay and in vivo induction of vitellogenesis and zonagenesis, two estrogen receptor (ER)-mediated responses that are integral aspects of fish oogenesis. The ER binding affinities of alpha-zearalenol and ZEA in rainbow trout (Oncorhynchus mykiss) were approximately 1/150 and 1/300 to that of estradiol, respectively. Juvenile salmon (Salmo salar) were exposed to a single intraperitoneal injection of ZEA, alpha-zearalenol and beta-zearalenol (each at 1 and 10 mg/kg) and compared to fish injected with estradiol-17 beta (E2; 5 mg/kg) and controls. Using indirect enzyme-linked immunosorbent assay (ELISA) with homologous antibodies, a dose-dependent induction of vitellogenin (Vtg) and eggshell zona radiata proteins (Zr-proteins) were observed 7 days after exposure to ZEA and alpha-zearalenol. beta-Zearalenol did not elevate plasma Vtg levels, but a non-significant elevation of plasma Zr-proteins levels was observed at the highest dose (10 mg/kg). Generally, alpha-zearalenol and ZEA possess estrogenic potencies that are approximately 50% compared to that of E2, and their order of estrogenic potency (in both in vitro receptor competitive binding and in vivo induction of Vtg and Zr-proteins levels) is: alpha-zearalenol > ZEA > beta-zearalenol. Our results show that blood plasma analysis of Vtg and Zr-proteins levels provides a suitable in vivo fish model for assessing the estrogenic potencies of ZEA and its metabolites.

A sensitive zonagenetic assay for rapid in vitro assessment of estrogenic potency of xenobiotics and mycotoxins

Mounting evidence confirms that hepatic biosynthetic processes are essential for female sexual maturation in fish, which is directly controlled by estrogens. These oogenetic events (zonagenesis and vitellogenesis) are induced in both sexes by estrogens. In this paper, we report the induction of zona radiata (zr) proteins and vitellogenin in primary hepatocytes from Atlantic salmon (Salmo salar L.) exposed to xenoestrogens and mycotoxins. Cells were treated with doses of 1, 5, and 10 microM 4-nonylphenol (4-NP), o, p'-DDT, lindane ([gamma]-HCH), and bisphenol A (BPA), which all induced zr proteins and vitellogenin in an approximate dose-dependent manner. Hepatocytes were also treated with combinations of xenoestrogens at 1 or 2 microM, resulting in elevated levels of both zr proteins and vitellogenin, compared to single treatment. The estrogenic activity of the mycotoxin zearalenone (ZEA) and its metabolites [alpha]-ZEA) and ss-zearalenol (ss-ZEA)], with regard to zonagenesis and vitellogenesis, was assessed in this assay system. Mycotoxins were used at concentrations of 10, 100, or 1,000 nM. All induced zr proteins and vitellogenin, with [alpha]-ZEA being the strongest inducer. When cells were treated with xenoestrogens or mycotoxins in combination with an estrogen receptor inhibitor (ICI 182,780), the induction of both zr proteins and vitellogenin was inhibited in all cases. Thus, the reported estrogen effects are bonafide estrogen responses. Zona radiata proteins were more responsive than vitellogenin to both xenoestrogens and mycotoxins. The versatility and sensitivity of the hepatocyte assay demonstrates that biosynthesis of zr proteins provides a new supplementary method for estimating xenoestrogenicity and mycotoxin action.

Maternal health and pre- and perinatal characteristics in the etiology of testicular cancer: a prospective population- and register-based study on Norwegian males born between 1967 and 1995

OBJECTIVES

The aim of the present prospective study was to identify possible risk factors of testicular cancer (TC) in relation to gestation and birth.

METHODS

Based on data from compulsory birth and cancer registration in Norway, odds ratios (ORs) of TC were estimated.

RESULTS

Among 868068 males born between 1967 and 1995, 268 cases of germ cancer had developed by June 1996, 32 TCs before 5 years of age and 236 TCs thereafter, 48 cases being seminomas and 220 non-seminomas. There was a tendency of an inverse association between parity and TC. A previous finding from Sweden linking neonatal jaundice to risk of non-seminomas was confirmed (adjusted OR = 2.1, 95 percent confidence interval [CI] = 1.3-6.9). Significant associations were also seen for seminomas and TC diagnosed after 5 years of age. Maternal disease diagnosed before pregnancy increased the risk of TC significantly, particularly in the age group 0-4 years: Adjusted OR = 3.0, CI = 1.4-6.3. Retained placenta was significantly associated with both seminomas and non-seminomas and with TC diagnosed after 5 years of age.

CONCLUSIONS

The findings of this study support the existing hypothesis that pre- and perinatal risk factors are of significance for development of TC in children and in young adults, and for seminomas and non-seminomas. The hypothesis that estrogens are involved in TC development was, among other factors, supported by the association of parity to TC. Additionally, on the basis of findings in maternal diseases and complications to pregnancy, we suggest that immune reactions during foetal life may be of significance for development of TC.

pH of human semen

The World Health Organization (WHO) laboratory manual (1992) states the normal values for pH in liquefied semen to be between 7.2 and 8.0. This implies an adjustment compared with the previous version (WHO, 1987) in which the upper limit was 7.8, whereas in the WHO clinical manual (1993) the normal range of values is still stated to be in the range of 7.2-7.8. In this study pH was measured in ejaculates from 207 men in couples undergoing infertility examination. The pH was measured within 30 and 60 min after ejaculation with both pH paper and pH meter. The mean pH values were consistently well above 8.0 regardless of analysis method and time after ejaculation. Since semen analysis is part of clinical assessment of male infertility and includes pH measurement, our findings suggest that the range of normal values needs to be revised further.

Endothelin and hemodynamic responses to superior mesenteric artery occlusion shock and hemorrhagic shock in pigs

Endothelin is a novel, potent, endogenous vasoconstrictor derived predominantly from endothelium and macrophages. Release of endothelin-1 (ET-1) into biological fluids was determined by radioimmunoassay in pigs undergoing either a hemorrhagic (3 h) or superior mesenteric artery (SMA) occlusion (5 h) shock followed by reperfusion (90 min) or a control group which was observed for 8 h. After surgery, there was a significant increase in ET-1 in jugular and carotid plasma, lymph, and ascitic fluid in all three models. The portal plasma ET-1 level was significantly increased (p < .05, assessed by the Spearman rank coefficient rho) in both shock models, but no significant increase was noted in the control group. In the SMA occlusion shock model, four pigs died within 30 min of reperfusion, and these animals had a much higher level of portal ET-1 (22.3 +/- 5.5 fmol/mL) than the two pigs that were alive by the end of the observation period (11.5 +/- 1.3 fmol/mL). Reperfusion in the SMA occlusion shock model induced a critical form of circulatory shock characterized by hypotension, decreased cardiac output, and decreased left and right ventricular stroke work index, and death occurred usually within 90 min. Reperfusion of the shed blood in the hemorrhagic shock model almost normalized the hemodynamic derangements caused by the hypovolemia (with the exception of RVSWI), and the portal plasma and ascitic ET-1 levels decreased. These results indicate that ET-1 is released from the gut in response to both general hypoperfusion and selective intestinal ischemia and reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in mucosal morphology and permeability, but no bacterial or endotoxin translocation takes place after intestinal ischemia and early reperfusion in pigs

Ischemia and reperfusion of the gut may be an important etiological factor in the development of multiple organ failure. We have used a hemorrhagic and a superior mesenteric artery (SMA) occlusion shock model in pigs to estimate the effect of ischemia and reperfusion on intestinal morphology, mucosal permeability, and the occurrence of bacterial or endotoxin translocation. Mucosal ulceration and necrosis were found in the SMA shock model, while the morphological changes were less pronounced in the hemorrhagic shock model. Scanning electron microscopy showed shrinkage of the villi and plugging of the colonic crypts in both shock models. Enterocyte cell kinetics was investigated using 5-bromo-2'-deoksyuridine (BrdU) incorporation and immunovisualization by anti-BrdU antibodies. Cell renewal was almost completely lost from the jejunum to the rectum in both shock models. Intramucosal pH was measured using a tonometer placed in the terminal ileum. Segments of intestinal mucosa were mounted in Ussing chambers, and permeability was measured using radiolabeled probe molecules of differing molecular weights. Augmented molecular flux of inulin (M(r) 5.000) and mannitol (M(r) 182) and loss of short circuit current (Isc) and transepithelial potential difference (PD) were found in mucosae from both shock models. Endotoxin was demonstrated in the ascitic fluid in both shock models; 9.5 (2.7-14.3) (median and 95% confidence interval) EU/mL in the SMA occlusion model and 16.0 (4.9-29.4) EU/mL in the hemorrhagic shock model), but the levels were not significantly higher than in the control model 6.5 (4.3-34.0) EU/mL.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of 4-acetylaminofluorene and other tumour promoters on hepatocellular growth and binucleation

The complete liver carcinogen 2-acetylaminofluorene (2-AAF) promoted the outgrowth of large neoplastic liver nodules and hepatocellular carcinomas in diethylnitrosamine-treated rats. 2-AAF did not alter the overall proliferative activity of normal hepatocytes, but suppressed binucleation and induced, on a long-term basis, an increase in proliferative activity and in the fraction of diploid hepatocytes relative to control animals. The analogue 4-acetylaminofluorene (4-AAF) was much less effective than 2-AAF as a promoter of large nodules and carcinomas, but promoted the outgrowth of medium-sized nodules (1 < 2.5 mm). While 2-AAF specifically stimulated the growth of cells in enzyme-altered foci, the cells responding to 4-AAF were more randomly distributed throughout the liver tissue. In contrast to 2-AAF, 4-AAF strongly stimulated the growth (DNA synthesis) of normal hepatocytes, but like 2-AAF it suppressed binucleation and caused a long-term increase in the proliferative activity and in the fraction of diploid hepatocytes. Other liver tumour promoters (cyproterone acetate, alpha-hexachlorocyclohexane, methylclofenapate) likewise stimulated the growth and suppressed the binucleation of normal hepatocytes. All hepatocellular ploidy classes were affected virtually equally by mitogenic stimulation, but at low proliferation rates the mononuclear cells were more proliferative than the binuclear cells. Since this difference could be eliminated by increasing the mitogen dose, it would seem that mononuclear cells may be somewhat more sensitive towards mitogens than binuclear cells. In contrast to previously reported results [Styles et al. (1990) Carcinogenesis, 11, 1149-1152], methylclofenapate was not found to specifically stimulate binuclear hepatocytes. Our results indicate that liver tumour promoters in general tend to induce a non-binucleating, non-polyploidizing hepatocellular growth pattern, similar to that observed during liver regeneration. 4-AAF is confirmed to be, at best, a very weak promoter of liver carcinogenesis, but appears to be an effective promoter of benign tumours.

Flow cytometric investigation of a possible precursor--product relationship between oval cells and parenchymal cells in the rat liver

The question of a possible precursor--product relationship between oval cells and hepatocytes was examined in rats treated for 2 weeks with 2-acetylaminofluorene (2-AAF) with a two-thirds partial hepatectomy (PH) performed after the first week of 2-AAF treatment (modified Solt-Farber model). Liver cells were pulse-chase labelled with bromodeoxyuridine (BrdU) on day 6 post PH. On day 7 post PH the nonparenchymal (NPC) fraction, which contains the oval cells, exhibited a labelling index (LI) approximately 10 times higher than that of the hepatocytes as analysed by flow cytometry (FCM), the majority of the proliferating cells being oval cells. At later time points, there was no significant increase in the LI of diploid hepatocytes, and no detectable shift of BrdU-labelled cells from the NPC fraction to the hepatocyte fraction, suggesting that no extensive conversion of BrdU-labelled oval cells to hepatocytes was taking place. Throughout the experimental period there was a significant increase in the diploid hepatocyte cell fraction, from 12% on day 7 to 25% on day 13 post PH. Diploid hepatocytes pulse-labelled on days 7 or 9 post PH had a high LI (7-8%), in contrast to the low LI (1%) of tetra- and octoploid cells. Proliferation of diploid hepatocytes may thus explain the large increase in the diploid hepatocyte fraction observed from days 9 through 15 post PH. Our results, therefore, provide no reason to invoke oval cells as precursors of hepatocytes in the modified Solt-Farber carcinogenesis model.

Binucleation and polyploidization patterns in developmental and regenerative rat liver growth

The hepatocellular binucleation rate, measured as the percentage of binuclear cells amongst newly formed bromodeoxyuridine-labelled and immunostained collagenase-isolated rat hepatocytes, decreased from 12% to 4% between days 30 and 40 after birth, rose to 20% between days 50 and 60, and then declined again to the adult rate of about 10% at day 80. During regenerative growth following a two-thirds partial hepatectomy, the rate of binucleation declined to about 3%, causing the fraction of binuclear cells to fall from 27% (before hepactectomy) to 5% (at 45 h after hepactectomy) as pre-existing binuclear cells replicated and formed mononuclear daughter cells. Essentially all (97%) hepatocytes replicated at least once, starting their DNA synthesis at around 13 h and reaching a peak at 30 h, irrespective of ploidy and nuclearity. At later time points, the diploid hepatocytes had a higher labelling index than the polyploid cells, suggesting a greater tendency to go through several cell cycles.

Atrial natriuretic factor (ANF) does not affect ion transport in human intestine but does in porcine intestine

The aim of this study was to test whether atrial natriuretic factor (ANF) exerts any effect on human intestinal ion transport, and the porcine intestine was used as a positive control of ANF's effects. Tissues from human proximal (n = 6) and distal (n = 6) colons, and from distal ileum (n = 6) were mounted in Ussing chambers, and short circuit current (Isc) was measured subsequent to serosal application of ANF (10(-6) M), 8-Br-cyclic guanosine monophosphate (8-Br-cGMP) (10(-4) M), and theophylline (10(-2) M). ANF did not affect Isc whereas 8-Br-cGMP increased Isc by 28 (8-53), 16 (3-36), and 16 (5-41) microA cm-2 in the distal colon (DC), proximal colon (PC) and distal ileum (DI), respectively. Likewise, transepithelial potential difference (PD) became more negative by 5.0 (0.6-8.9), 2.5 (0.4-4.0) and 0.9 (0.3-2.3) mV in DC, PC, and DI, respectively, subsequent to addition of 8-Br-cGMP. Isc and PD were further increased by theophylline. Additional radio-isotope flux studies in human colon revealed that ANF did not affect electroneutral sodium and chloride transport either. For comparison, ANF (10(-6) M) was administered to large intestinal tissues from young pigs in which ANF induced a significant increase in Isc which was comparable to the 8-Br-cGMP response in humans. The porcine Isc response was partly inhibited by chloride-free solution on the serosal side, by serosal application of bumetanide (10(-4) M) and BaCl2 (10(-3) M), and mucosal application of the chloride-channel blocker diphenylamine-2-carboxylate (DPC) (10(-3) M). Mucosal amiloride (10(-5) M) pre-treatment reduced baseline Isc but did not affect the porcine intestinal Isc response to ANF. In vitro radio-autography demonstrated specific binding sites for ANF in porcine distal colon, whereas no apparent labelling was observed in human distal colon. These findings suggest that the lack of effect of ANF on sodium and chloride transport in human distal ileum and colon is probably due to lack of ANF receptors. In the porcine intestine, however, the Isc response induced by ANF seems to involve stimulation of electrogenic chloride secretion, whereas electrogenic sodium absorption seems unaffected.

Prostaglandin- and theophylline-induced C1 secretion in rat distal colon is inhibited by microtubule inhibitors

The aim of the present study was to examine the possible role of microtubules in chloride secretion by distal rat colon stimulated by prostaglandin (PGE2) and theophylline. Distal colonic tissue from male rats was mounted in Ussing chambers, and short-circuit current (Isc) was measured to assess chloride secretion. Three microtubule inhibitors, colchicine, nocodazole, and taxol, all inhibited the stimulated Isc and reduced the 60-min integrated secretory response to PGE2 and theophylline (integral of Iscdt) by 39-52%, whereas the inactive colchicine analog lumicolchicine did not. Atropine and tetrodotoxin had no effect on stimulated chloride secretion. To confirm the source of Isc, unidirectional 22Na+ and 36Cl- fluxes were measured in tissues exposed to lumicolchicine (control) or colchicine. Control tissues absorbed both chloride [5.0 (1.1-8.6) (median and 95% confidence interval) mueq/cm2/hr] and sodium [2.8 (0.9-7.2) mueq/cm2/hr], and this net absorption was reduced by 96% and 79%, respectively, by treatment with PGE2 and theophylline due to an increase in serosal-to-mucosal chloride and sodium movement. Colchicine-treated tissues exhibited similar net basal chloride and sodium absorption that was reduced by 71% and 75%, respectively, by treatment with PGE2 and theophylline. Thus the PGE2- and theophylline-induced increase in chloride secretion was significantly reduced by colchicine (P < 0.05 by Wilcoxon rank-sum test), whereas colchicine had no effect on PGE2- and theophylline-induced changes in sodium fluxes. Furthermore, the colchicine-related changes in stimulated chloride secretion were numerically similar to colchicine-related changes in stimulated Isc.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced proliferative activity of polyploid cells in primary hepatocellular carcinoma

The proliferative activity of tumor cells differing in DNA content (ploidy) and nuclearity was investigated in primary hepatocellular carcinomas of the rat by flow cytometric analysis of collagenase-isolated cells immunostained after labelling with bromodeoxyuridine (BrdU) in vivo. The diploid cell fraction in these euploid tumours was higher than in normal liver, and the rate of binucleation as well as the proliferative activity of the binuclear cells was very low. The highest proliferative activity (BrdU labelling index) was found among the diploid tumour cells. The activity in mononuclear tetraploid and octoploid cells was reduced in inverse proportion to their increasing DNA content, possibly suggesting a loss of proliferative potential associated with polyploidization. There was a significant correlation between the proliferative activity of hepatocellular carcinoma cells and nonparenchymal liver cells in the different tumours, indicating that different cell types within a tumour may respond to common growth stimuli. Treatment of tumour-bearing rats with a promoting carcinogen (2-acetylaminofluorene) resulted in significant stimulation of tumour cell proliferation (all ploidy classes), whereas the proliferation of non-parenchymal (stromal) cells in the tumour was slightly inhibited.

Analytical methods for the study of liver cell proliferation

Various cytometric methods for analysis of regenerating rat liver growth (DNA ploidy distributions, binucleation, and DNA synthesis by in vivo BrdUrd incorporation) were evaluated. The overall hepatocellular growth rate (labeling index), the binucleation rate, and separate indices for mononuclear and binuclear cells could be measured simply by microscope counting of collagenase-isolated hepatocytes immunostained for BrdUrd. Flow cytometry of cells stained for BrdUrd and DNA provided labeling indices for the various hepatocellular DNA ploidy classes as well as for nonparenchymal cells (identified by their size-dependent light scatter), but could not distinguish between mononuclear and binuclear hepatocytes. Image cytometry, using fluorescence or Feulgen staining, was inferior to flow cytometry in terms of speed and DNA resolution, but allowed a complete analysis of all hepatocellular DNA ploidy and nuclearity classes. It may therefore be the method of choice, particularly for analysis of liver cell cultures from which single cells are not easily obtained. Fluorescence staining would seem to be preferable to Feulgen staining, since the latter could not be used simultaneously with BrdUrd staining and therefore required a two-step analysis. A non-immunological method, based on the ability of incorporated BrdUrd to quench DNA staining by a Hoechst dye, could only be applied to isolated nuclei, thus giving no information about binucleation. The latter method may be useful for analysis of tumors which are difficult to dissociate to intact whole cells.