Neuromuscular Responses to 14 Weeks of Traditional and Daily Undulating Resistance Training.

This study compared traditional (TP) and daily undulating (DUP) periodization on muscle strength, EMG-estimated neural drive and muscle architecture of the quadriceps femoris (QF). 10 non-athletic females (24.4±3.2 years) performed 14 weeks of isometric training for the QF exercising 1 leg using TP and the contralateral leg using DUP. Intensities varied from 60% to 80% of MVC and the intensity zones and training volume were equated for each leg. Knee extension MVC, maximal voluntary QF-EMG activity and vastus lateralis (VL) muscle architecture were measured in both legs before, after 6 weeks and after 14 weeks of training using dynamometry, surface EMG and ultrasonography. Isometric MVC and maximal QF-EMG remained unaltered after 6 weeks of training, but were significantly (P<0.05) enhanced after 14 weeks in both legs (MVC: TP 24%, DUP 23%; QF-EMG: TP 45%, DUP 46%). VL-architecture remained unchanged following 6 weeks of training, but VL-muscle thickness (TP 17%, DUP 16%) and fascicle length (TP 16%, DUP 17%) displayed significant (P<0.05) enlargements after 14 weeks in both legs. Importantly, these temporal neuromuscular alterations displayed no significant differences between the training legs. Therefore, periodization may not act as a key trigger for neuromuscular adaptations.

Cracking susceptibility of sweet cherries (Prunus avium L.) under different conditions.

Rain and hail during ripening and harvesting season can cause yield losses up to 90 % in sweet cherry cultivations in Germany. Particularly, high yield losses after precipitation are due to the cracking and the following rotting process through bacteria and fungi's. In order to protect the crop and improve cherry quality they can be treated with chemicals dried or healthier covered with rain shelters. To date the cracking phenomenon of cherries is still not clearly understood. Therefore, in the present study the cracking resistance of three cherry varieties under different conditions was observed. We used 'Regina', 'Karina', and 'Summit' grafted on the rootstock GiSelA 5. The test-section in the field was covered with a plastic-foil (pc) as rain shelter and a bird net, whereby the control (c) was covered with a bird protection-net only. The cherry varieties have been harvested, weight and sorted into undamaged, rotten and cracked fruits. In order to compare the varieties under equal conditions the cracking sensitivity was also tested under laboratory conditions with the method from CHRISTENSEN (1996). The average yield per tree was significantly higher in the pc treatment in 'Summit' and 'Regina' than in the control. Furthermore, the average weight of rotten fruits per tree in these varieties was in c, without rain shelter, about two to three times higher as in the pc treatment. There was no significant difference in yield and rotten fruits among treatments in 'Karina'. But the percentage of cracked fruits between the cultivation methods was significant different. Hereby improvement of cherry quality was observed in the pc treatment with reduced numbers of useless fruits. Under field conditions 'Karina' was at least susceptible to cracking resistance followed by 'Regina' and 'Summit'. In the laboratory Cracking Test the result was different. Here, the variety 'Summit' showed the best cracking resistance compared to the other varieties. According to the method of CHRISTENSEN (1996) it was impossible to calculate a Cracking Index (CI) from 'Summit' because of a too little number of cracked fruits. The CI of 'Karina' was 22 under cover and 36.8 in the control without cover. 'Regina' performed better with a CI from 6.8 under plastic cover compared to 15.6 in the control. Therefore, the cracking susceptibility of varieties was different under field and laboratory conditions. In conclusion the distribution of the raindrops on the outer layers of the cherries, the ingredients (sugar) and morphology of cherries (fruit firmness) play an important role in the cracking process. The result with different cultivation methods and the different reaction of the fruits in the Cracking Index trial relate to morphological dissimilarities of tested varieties. Using rain shelters can clearly reduce the cracking of cherries and the following rotting process.

Variability of aliphatic glucosinolates in Arabidopsis and their influence on insect resistance.

Due to the sessile nature of plants they have to cope up dynamically with diverse biotic and abiotic stressors. Plants developed diverse, complex defense mechanisms for dealing with their enemies, including the glucosinolate(GS)-myrosinase system of the Brassicaceae and other families of the order Brassicales. GS are classified by their precursor amino acid and aliphatic, aromatic, and indolyl GS are distinguished. Indolyl GS are widely distributed in Arabidopsis thaliana (L.) ecotypes and the Brassicaceae family, but the presence of aliphatic GS is variable and under strong genetic control. There are only few studies paying attention to the impact of certain GS on insect resistance. Due to this, we have investigated the plant resistance of A. thaliana ecotypes with different aliphatic profiles against two specialized insects. For the experiments we selected 20 ecotypes, divided into three groups after HPLC analysis: containing 1) methylsulfinyl, 2) 3-hydroxypropyl, and 3) allyl GS. As herbivore insects the generalist Spodoptera exigua Hübner and the specialist Pieris brassicae L. were selected. The selected A. thaliana ecotype groups were different suitable for consumption, but similar for both insect species. In general, the percentage weight gain of larvae on A. thaliana plants containing 3-hydroxypropyl GS and allyl GS was significantly higher for both insect species, the specialist and the generalist, compared to methylsulfinyl GS containing ecotypes. But the tendency was stronger for P. brassicae than for S. exigua. Additionally, we used simple correlation to examine the relationship between insect feeding and the GS contents in the ecotypes. It can be concluded that 3-hydroxypropyl GS containing ecotypes were less resistant than ecotypes with methyl-sulfinyl GS as main compounds. Weight gain by S. exigua was statistically significant negatively related to constitutive GS levels of methylsulfinyl GS containing ecotypes. There was also a negative relation to constitutive GS levels of methylsulfinyl GS containing ecotypes for P. brassicae but less strong and not statistically significant. A reason for a better host plant suitability of ecotypes containing 3-hydroxypropyl GS might be the short chemical structure and/or different reactivity of this compound compared to ecotypes containing methylsulfinyl GS.

Evidence for quiescent S- and G2-phase cells in human colorectal carcinomas: a flow cytometric study with the Ki-67 antibody.

The expression of certain antigens specific for proliferating cells can be determined simultaneously with cell cycle distribution by means of two-dimensional flow cytometry. In this way, a tumour's growth potential is characterized more precisely than with any one parameter alone. Here we describe such simultaneous measurements of DNA content and labelling with the Ki-67 antibody that distinguishes between cycling and non-cycling cells. Having overcome a number of technical problems we were able to analyse material from 29 biopsies of human colorectal tumours. In a number of cases, Ki-67 negative cells were found with a DNA-content of G0/1 only, whereas all cells with an S- or G2-phase DNA-content were Ki-67 positive. There were other cases in which cells with an S- and G2-phase DNA-content had obviously become quiescent (Ki-67 negative), sometimes even outnumbering the proliferating (Ki- 67 positive) cells in the respective compartments of the cycle. Generally, however, when Ki-67 negative and positive subpopulations were analysed separately it was found that the former had a significantly lower (S + G2)-phase fraction than the latter. There was evidence for a correlation between Ki-67 index and (S + G2)-phase fraction at least in the subgroup of aneuploid tumours. Neither of the two parameters was correlated with stage according to Duke's classification or tumour size. However, a positive correlation was found between the fraction of unlabelled S- and G2-phase cells and tumour size as reflected in the T category.

Combined effects of X rays, Ro 03-8799, and hyperthermia on growth, necrosis, and cell proliferation in a mouse tumor.

A mouse adenocarcinoma was treated with 20 Gy X rays, hyperthermia (30 minutes at 43 degrees C), Ro-03-8799, or a combination of two or three of these agents. Combined treatments increase growth delay in the tumor and this was greatest with the combination of all three modalities. Extensive amounts of necrosis were observed after the combined treatments. This effect was most pronounced after treatment modalities including hyperthermia. On the other hand, the radiation-induced micronucleus formation was more enhanced by the sensitizer than by hyperthermia. After X irradiation and combined treatments with X rays a G2-block was observed in DNA-histograms. Tetraploid cells appeared in large amounts that started DNA synthesis followed by necrosis. From these tumors it was impossible to obtain regular DNA-histograms. Tumor regression is a combined result of reduced cell renewal, increased cytogenetic damage, and development of necrosis.

Changes in S-phase fraction and micronucleus frequency as prognostic factors in radiotherapy of cervical carcinoma.

Twenty-five patients with cervical carcinoma were treated with combined external beam and high dose rate afterloading radiotherapy. Biopsies obtained at different time points in the course of therapy were analysed with respect to cell proliferation and cytogenetic damage. The fraction of cells with an S-phase DNA-content as well as the frequency of micronuclei were determined. These two parameters were then related to treatment outcome, in particular patient survival. Neither S-phase fraction nor the micronucleus frequency before radiotherapy were predictive of treatment outcome in this small group of patients. However, when changes in response to therapy were considered, patients whose S-phase fraction decreased and patients whose micronucleus frequency increased tended to have a better prognosis. Although statistical significance was not achieved with either criterion alone, when applied together the combination predicted patient survival quite reliably; the 5-year survival rate of those patients who showed a decrease in S-phase fraction as well as an increase in micronucleus frequency was about 90% in contrast to less than 30% for the non-responders (p < 0.03).

Induction of quiescent S-phase cells by irradiation and/or hyperthermia. I. Time and dose dependence.

DNA synthetic activity and DNA content of individual cells can be determined simultaneously by means of two-parameter flow cytometry. We used this method to study the effects of irradiation and/or hyperthermia on the proliferation of human melanoma cells in vitro. In untreated cultures, most of the cells with an S-phase DNA content showed incorporation of BrdU, but a small percentage did not. The fraction of these quiescent S-phase cells increased after irradiation (up to 8 Gy X-rays) and/or hyperthermia (up to 6 h at 42 degrees C or up to 2 h at 43 degrees C). Four days after the treatment up to 50% of the S-phase cells did not incorporate BrdU. There was a clear dose dependence for irradiation and hyperthermia alone or in combination. Generally, the combined effects seemed to be additive. Possible pitfalls of the technique used were taken into consideration. Our main practical conclusion is that single-parameter measurements of DNA content are insufficient to characterize the proliferative status of cell populations, especially after irradiation and/or hyperthermia, because a large part of those cells identified as being in S-phase may be quiescent.

Induction of quiescent S-phase cells by irradiation and/or hyperthermia. II. Correlation with colony forming ability.

Quiescent S-phase cells, i.e. cells with an S-phase DNA content that do not show BrdU incorporation, can be induced in a dose-dependent manner by irradiation and/or hyperthermia (Zölzer et al. 1992). As they begin to appear only 48-72 h after treatment, they do not seem to be related to early cell cycle disturbances, but rather to late events involved with cell death. We therefore determined colony forming ability under the same conditions, and tried to correlate the two parameters. Although, in general, higher frequencies of unlabelled S-phase cells were associated with lower survival, there were interesting differences. At the same level of survival, for instance, quiescent cells were induced more efficiently by hyperthermia than by irradiation. Additional experiments with split dose protocols showed that while cell killing was reduced by fractionation, the frequency of unlabelled S-phase cells increased. This further corroborates our conclusion that there is no simple relationship between the two parameters. Quiescence in S-phase is not just an expression of cell death irrespective of the treatment by which it may have been caused.

Prospective flow cytometric analysis of head and neck carcinomas. Prognostic relevance of DNA-content and S-fraction.

Flow cytometric data were obtained from 142 primary squamous cell carcinomas of the oral cavity or the oropharynx. Aneuploidy was found in 36.8% of the tumours. The DNA indices showed a significant correlation with the S-fraction, tumour size and evidence of suspicious lymphnodes. There was no clear correspondence between the S-fraction and the tumour stage. Tumour size, histopathologically-positive lymphnodes and the mode of treatment were significantly correlated with the survival rates. In contrast, there was no clear correlation between flow cytometric data and the prognosis of the whole group as well as several clinical subgroups. In 40 patients who received preoperative irradiation, DNA indices and S-fractions were compared before and after the preoperative treatment. In 12 of 14 aneuploid tumours irradiation led to a decrease in the DNA indices into the range of euploidy. Only 2 tumours remained aneuploid. After irradiation 26 of 37 tumours showed a decrease in S-fraction, 11 tumours showed an increase. Loss of aneuploidy after irradiation was associated with a histologically-proven increasing devitalization of tumour cells, decrease in S-fraction corresponded to a tendency to a better prognosis.

Modulation of cardiac hypertrophy by estrogens.

Gender-specific differences in heart disease have long been known but it has only been since the advent of molecular biology that it has become possible to investigate the molecular mechanisms. Most biochemical work in the last 50 years has focused on the characterization of the steroid hormones involved in gender specificity. More recently, the cloning of the steroid receptors and characterization of the signaling pathways through these proteins has given new insights into the mechanisms underlying the mode of action of steroid hormones. It has also become clear that the steroid receptors can be classified into families (receptors for thyroid hormone, glucocorticoids, estrogens, androgens, retinoic acid, and so called orphan receptors of mostly unknown function). The structures of these receptors show very close resemblance and all are DNA-binding proteins acting as transcription factors. Some (if not all) act as repressors of transcription of some genes in the native state and are converted to activators (or perhaps repressors of other genes) upon binding of the cognate hormone. Naturally, classical target tissues for estrogens and androgens have been studied first and only in very recent years has it been recognized that estrogens and androgens act on a much wider spectrum of tissues. In the cardiovascular field, the beneficial effect of estrogen replacement therapy in postmenopausal women which reduces the incidence of cardiovascular disease by some 40% and the lower incidence of cardiovascular disease in premenopausal women have mostly been explained by the beneficial action of estrogens on the lipid profile (increase in HDL and decrease in LDL cholesterol). Recently, functional estrogen receptors have also been shown in vascular smooth muscle cells and in the endothelium. Our own group has characterized the presence of estrogen receptors in the myocardium and in cardiac fibroblasts. We have also shown that these receptors are transcriptionally active because they are able to drive a minigene composed of a triple estrogen responsive DNA regulatory element (promoter) coupled to the firefly luciferase gene which serves as a reporter by way of its ability to drive a light-emitting reaction. We are in the process of characterizing the target genes for estrogen in the myocardium. A specific series of immediate-early genes is induced by estradiol (the major premenopausal estrogen) and we have also characterized a number of tissue-specific genes whose expression is driven by estrogens in the myocardium. The ultimate goal of these investigations is to explore the use of estrogens in the treatment of cardiac hypertrophy (and failure) by way of their properties to counteract (at least some of) the pathological switches in gene expression in these disease entities.

Functional effects and molecular mechanisms of subtype-selective ERalpha and ERbeta agonists in the cardiovascular system.

Gender differences in the development of cardiovascular disease suggested for a protective function of estrogens in heart disease. The negative or neutral outcome of clinical trials on hormone replacement therapy provides clear evidence that the role of female sex hormones in the cardiovascular system is more complex than previously thought. In particular, the function of estrogens can not be understood without detailed knowledge on the specific function of both estrogen receptor subtypes in the heart and in the vasculature. In here, we review recent studies on subtype selective ERalpha and ERbeta agonists in different animal models of hypertension, cardiac hypertrophy and vascular inflammation. The results indicate that the activation of specific ER subtypes confers specific as well as redundant protective effects in hypertensive heart disease that might ultimately translate into novel treatment options for hypertensive heart disease.

[Molecular adaptation of the heart to hypertension]. / Molekulare Adaption des Herzens an Hypertonie.

Because myocardial hypertrophy is an independent risk factor for sudden death and cardiac failure, it is important to understand its molecular mechanisms to be able to devise new treatment strategies in the future. Stretch is the putative primary stimulus triggering hypertrophy. Further signal transduction steps such as auto- and paracrine secretion of growth factors or transmission via the cytoskeleton are beginning to be unravelled. Subsequent to hypertrophic stimuli some important proteins undergo an isoform switch; questitatively, however, the most important step is an increase in translational capacity for each mRNA. Myocardial specific gene expression is achieved by coordinate interaction of several transcription factors, some of which may be involved in nuclear transmission of hypertrophic signals. One of the genes capable of transmitting hypertrophic signals is the "early growth response gene-1 (Egr-1)". We have also shown that nuclear estrogen receptors act as transcription factors in the myocardium and may therefore be involved in the sex-specific modulation of cardiac hypertrophy. At present, pharmacological interventions aiming at reduction of hypertrophy by interfering with the signal transduction pathway from the membrane to the nucleus are actively being sought. These transduction pathways are composed of a series of proteinkinases which may be amenable to drugs. In the future, gene transfer may become an option for treatment.

The biological cascade leading to cardiac hypertrophy.

Cardiac hypertrophy, one of the major risk factors in hypertension, is associated with a high incidence of congestive heart failure and sudden death. Despite efforts over the last 20 years, the underlying molecular mechanisms of cardiac hypertrophy are still poorly understood, thus making it difficult to develop new therapeutic strategies. A growing body of evidence suggests that cardiac hypertrophy results from mechanical stress that triggers paracrine and autocrine signal transduction pathways. Furthermore, whereas hypertrophy leads to isoform switches in some contractile proteins, increased protein synthesis is largely based on increased translational capacity. Cardiac growth under physiological as well as pathological conditions is regulated by several recently identified transcription factors. Among the factors that are capable of transmitting hypertrophic stimuli to the nucleus is the early growth response gene-1 (Egr-1). Whereas female gender is already an established cardioprotective factor in clinical trials, some very recent data indicate that oestrogens and the nuclear oestrogen receptor may directly modulate gene expression in the development of cardiac hypertrophy. Future pharmacological interventions could be directed towards modifying the nuclear signal transduction cascade involving multiple protein kinases and phosphatases.

Estrogen effects in the heart.

Gender specific differences in cardiovascular disease are largely mediated by sex hormones. The use of estrogens significantly reduces the overall incidence of heart disease in postmenopausal women. Beneficial effects of estrogens on plasma lipoprotein levels are clearly established. However, these do not explain the magnitude of risk reduction seen in clinical studies. Thus additional and currently unknown functions of estrogens must be operative. Elucidation of the exact estrogen action in the heart will have important implications in the treatment of cardiovascular disease. It will probably enhance the therapeutic repertoire in treating heart disease, the most common cause of death in industrialized countries. We will review the current understanding of the function of estrogens in the heart and discuss potential strategies on how to apply these data to clinical practice.

Induction of Egr-1 mRNA and protein by endothelin 1, angiotensin II and norepinephrine in neonatal cardiac myocytes.

The early growth response gene Egr-1 is a nuclear transcription factor known to serve as an intermediary in a broad range of signal transduction processes. Recent studies have assigned Egr-1 a new role as an amplifier of gene expression. Egr-1 mRNA is expressed in the myocardium and is rapidly induced in response to hypertrophic stimuli. However, induction of the Egr-1 protein has not yet been demonstrated in the myocardium; on the other hand, in skeletal muscle cells we have shown translational regulation of Egr-1. To further investigate the role of Egr-1 in the regulatory mechanisms of a variety of signal transduction processes we have therefore asked whether bona fide hypertrophic stimuli induce Egr-1 protein subsequently to its mRNA in neonatal rat cardiomyocytes or whether translational block occurs. In confocal laser studies the Egr-1 protein was nuclearly localized. Norepinephrine (NE, 2 microM), angiotensin II (AII, 0.1 microM), and endothelin 1 (E1, 0.1 microM) each induced the Egr-1 mRNA 6-8 fold and the Egr-1 protein 3-5 fold (n = 3, p < 0.01). Therefore, in contrast to skeletal muscle cells, these stimuli increased Egr-1 mRNA and protein levels. These results point further to the role of Egr-1 as a possible amplifier of signal transduction in the myocardium.

Cloning and characterization of the murine homolog of the sno proto-oncogene reveals a novel splice variant.

The cellular function(s) of the SNO protein remain undefined. To gain a better understanding of possible developmental roles of this cellular proto-oncogene, we have cloned two murine sno cDNAs and have investigated their expression patterns in embryonic and postnatal tissues. A single major transcript of 7.5 kb is detected in multiple tissues by Northern blot. However, reverse transcriptase polymerase chain reaction (RT-PCR) and RNAse protection assays revealed a novel splice variant in every tissue examined. Two isoforms, termed sno N and sno-dE3 (dE3, deletion within exon 3), were identified. The sno-dE3 isoform employs a novel 5' splice site located within the coding region of the third exon and deletes potential kinase recognition motifs. Transcripts of both sno isoforms accumulate ubiquitously but are most abundant in the developing central nervous system. The in situ hybridization patterns of sno expression during murine development suggest potential roles in tissues with a high degree of cellular proliferation. Expression in terminally differentiated tissues such as muscle and neurons indicates that SNO may have multiple functional activities.

Estrogen effects in the myocardium: inhibition of NF-kappaB DNA binding by estrogen receptor-alpha and -beta.

We have previously shown that estrogen effects in the heart include direct hormone effects on the myocardium. In a recent study we found that one beneficial effect of estradiol on the myocardium is the inhibition of apoptosis in cardiac myocytes. This effect was associated with a reduction of NF-kappaB activity. In the present study we have analyzed the functional mechanism of NF-kappaB inhibition in the myocardium by estrogen receptors-alpha and -beta. Despite the previous finding that 17-beta-estradiol (10 nM) inhibited the staurosporine-induced binding of p65/p50 NF-kappaB complexes to their cognate DNA elements in cultured rat cardiac myocytes, myocyte extracts showed no change in expression or cellular localization of p65, p50, and IkappaB upon staurosporine or estradiol treatment. Addition of either estrogen receptor-alpha or estrogen receptor-beta as recombinant protein was sufficient to inhibit staurosporine-dependent p65/p50 DNA binding in cardiac myocytes. 17-beta-Estradiol inhibits staurosporine-induced p65/p50 DNA binding associated with apoptotic cell death of cardiac myocytes via estrogen receptors-alpha and -beta. This is not associated with changes in p65, p50 and IkappaB expression or subcellular localization. Thus, inhibition of NF-kappaB activity by estrogenic compounds might inhibit NF-kappaB dependent gene expression such as pro-inflammatory cytokines in the myocardium.

Mechanisms of estrogen receptor action in the myocardium. Rapid gene activation via the ERK1/2 pathway and serum response elements.

We have previously shown that the myocardium is a target tissue for estrogen. Here, we have identified rapid non-nuclear estrogen effects on the expression of the early growth response gene-1 (Egr-1) in cardiomyocytes. Egr-1 mRNA and protein were rapidly and strongly induced by estrogen in an estrogen receptor-dependent manner via the extracellular signal-regulated kinase, ERK1/2. A promoter analysis study of a 1.2-kilobase Egr-1 promoter fragment revealed that the serum response elements (SREs) but not the estrogen response elements or AP-1 sites are responsible for Egr-1 induction by estrogen, identifying a novel mechanism of estrogen receptor-dependent gene activation in the myocardium. Both estrogen receptor-alpha and -beta induced the Egr-1 promoter via the SREs as well as an artificial promoter consisting of only five SREs in cardiomyocytes. Electrophoretic mobility shift assays showed that a protein complex containing serum response factor or an antigenically related protein was recruited to the SREs by estrogen treatment of primary cardiomyocytes. The recruitment of the protein complex was inhibited by the specific estrogen receptor antagonist ICI 182,780 as well as the MEK inhibitor PD 98059. Taken together, these results identify SREs as important promoter control elements for an estrogen receptor-dependent mechanism of gene activation in the myocardium.

17beta-estradiol prevents programmed cell death in cardiac myocytes.

The cardioprotective effects of estrogens are clearly established. However, the underlying mechanisms are poorly understood. Because programmed cell death (apoptosis) probably contributes to the loss of cardiac myocytes in heart failure and because estrogens prevent apoptosis in breast cancer cells, we investigated whether the loss of cardiac myocytes by programmed cell death could be prevented by physiological doses of 17beta-estradiol. Apoptosis of cultured cardiac myocytes was induced by staurosporine. 17beta-estradiol (10 nM) had an antiapoptotic effect as determined by morphological analysis, vital staining using the Hoechst dye 33342 and terminal transferase dUTP nick-end labeling (TUNEL). As a potential mechanism for the antiapoptotic effect of 17beta-estradiol we found a reduced activity of the ICE-like protease caspase-3 in hormone-treated myocytes. Furthermore, inhibition of apoptosis by estradiol was associated with a reduced activity of NF-kappaB transcription factors, particularly p65/RelA and p50. To our knowledge, these data provide the first indication that 17beta-estradiol in physiological concentrations inhibits apoptosis in cardiac myocytes. The antiapoptotic effect of estrogens might contribute to the known cardioprotective effect of estrogens and provides a starting point for the development of future treatment options.

Flow cytometric analysis of colorectal mucosa from patients with Crohn's disease, ulcerative colitis and cancer.

Samples of colorectal mucosa from patients with Crohn's disease, ulcerative colitis and cancer were analyzed by means of flow cytometry. S- and G2-phase fractions were determined and mean values were calculated for different groups of patients. Almost identical results were obtained for inflamed and normal appearing mucosa from patients with Crohn's disease as well as inflamed mucosa from patients with ulcerative colitis. The mean S- and G2-phase fractions in normal appearing mucosa from cancer patients, however, were significantly higher. This seems to be due to the fact that patients with Crohn's disease are between 15 and 45 years old, while cancer patients are mostly over 45. A detailed analysis of the S- and G2-phase fractions in different age groups revealed a slight, but significant increase in colorectal proliferation between 25 and 75 years.