Total Number Of Nuclei Research Articles

Dynamics of atmospheric nucleation mode particles: a timescale analysis

A theoretical framework was constructed by which one can estimate the relative role of different processes in thedynamics of atmospheric nucleation mode particles. The framework relies on 14 timescales that describe (1) changes inthe total nuclei number concentration, (2) changes in the mean diameter of the nucleation mode and (3) concentrationsof low-volatile vapours responsible for the growth of nuclei. The magnitude of the derived timescales can be calculatedrelatively easily from the available measurement or modelling data. Application to the lower-troposphere revealed thatunder most conditions removal of nuclei is dominated by their coagulation with larger background particles and thatthis process competes very strongly with growth of nuclei to sizes relevant to atmospheric chemistry and physics.Withsome exceptions, self-coagulation of nuclei was shown to be of marginal importance compared with their growth bycondensation and their removal by coagulation. Finally, by comparing predictions based on relevant timescales withthose obtained from detailed numerical simulations, quantitative criteria were derived concerning (1) when one mayneglect self-coagulation of nuclei when looking at nucleation mode dynamics and (2) when the whole nucleation modecan be neglected because of its eventual removal. These criteria are extremely useful for atmospheric modellers whoneed to simplify their models as much as possible. From the modelling point of view, other processes requiring furtherattention are the introduction of new nuclei into the system and decrease in nuclei number concentration due to dilutionof the air.

Wound splinting modulates wound cell proliferation

Introduction: Rigid anchorage of the extracellular matrix is important for fibroblast survival and proliferation in vitro. We hypothesized that rigid matrix anchorage in a wound splinting model would modulate wound cell proliferation in vivo.Methods: Male rats (age = 3 months; N = 12) were excisionally wounded (4 cm2 square of dermis + panniculus from the dorsum), and a square stainless steel splint was sutured to the wound edge. The splint was removed on day 5 from 6 rats. The animals were injected with BrdU 18 hr later, and then the granulation tissue with surrounding dermis was excised 24 hr after desplinting. BrdU- and propidium iodide-labeled nuclei were quantified on frozen sections of granulation tissue, cut at three different levels. Results: A total of 201 microscopic sections were counted (about 16 per rat), representing about 37,000 nuclei. The rate of BrdU-positive nuclei in the splinted vs. desplinted animals was 6.15 ± sd 2.45 vs. 3.03 ± 1.58%∗, and the total number of nuclei per microscopic field was 175 ± 27 vs. 197± 38∗, respectively (∗p < 0.001, unpaired t-test). Wound cross-sectional area decreased approximately 50% after desplinting (data not shown). Conclusions: Removal of the rigid wound splint decreased the rate of BrdU-labeled cells in the granulation tissue by 50%; there was a slight increase in the cell population density, which may be explained by the contraction which occurs after desplinting. Wound cell proliferation is modulated by anchorage of the wound edge.

Formation of droplets on active centers in supersaturated vapors

Kinetics of nucleation on active centers in supersaturated vapors is studied by a numerical solution of kinetic equations, including depletion of active centers during the phase transition process. The basic characteristics of the nucleation process (the size distribution of nuclei, nucleation rate and the total number of nuclei) are determined at various conditions. Nuclei are formed on all active centers at a sufficiently long time in coincidence with a widely used Avrami model. An increase of the total number of nuclei with time is steeper in the Avrami model as compared with our numerical solution of kinetic equations. The nucleation rate does not reach its stationary limit and becomes negligibly small with increasing time.

Primary Crystal Nucleation and Growth Regime Transition in Isotactic Polypropylene

We studied nucleation and crystal growth in two polypropylene samples by analyzing the number of spherulites, their size, and shape for various treatments in a hot-stage microscope. The consistency of nucleation and growth data were tested by using overall crystallization experiments and the Johnson–Mehl–Avrami–Kolmogorov equation. In isothermal conditions, for temperatures, T C , varying between 123° and 138°C, the number of crystallites per unit area does not depend on crystallization time and temperature. Instead, at small undercoolings (for T C >138°C), the total number of nuclei per unit area remains independent of crystallization time, but decreases with increasing temperature. We discuss the implications of this finding for the final microstructure of the crystallized samples. It is noteworthy that the passage between these two nucleation behaviors coincides with the transition from regime III to regime II, observed in the crystal growth kinetic analysis. This remarkable correlation between primary nucleation and crystal growth regimes is discussed.

Regenerative potential of human skeletal muscle during aging.

In this study, we have investigated the consequences of aging on the regenerative capacity of human skeletal muscle by evaluating two parameters: (i) variation in telomere length which was used to evaluate the in vivo turn-over and (ii) the proportion of satellite cells calculated as compared to the total number of nuclei in a muscle fibre. Two skeletal muscles which have different types of innervation were analysed: the biceps brachii, a limb muscle, and the masseter, a masticatory muscle. The biopsies were obtained from two groups: young adults (23 +/- 1.15 years old) and aged adults (74 +/- 4.25 years old). Our results showed that during adult life, minimum telomere lengths and mean telomere lengths remained stable in the two muscles. The mean number of myonuclei per fibre was lower in the biceps brachii than in the masseter but no significant change was observed in either muscle with increasing age. However, the number of satellite cells, expressed as a proportion of myonuclei, decreased with age in both muscles. Therefore, normal aging of skeletal muscle in vivo is reflected by the number of satellite cells available for regeneration, but not by the mean number of myonuclei per fibre or by telomere lengths. We conclude that a decrease in regenerative capacity with age may be partially explained by a reduced availability of satellite cells.

Stage of the estrous cycle at the time of pregnant mare's serum gonadotropin injection affects pre-implantation embryo development in vitro in the mouse.

The present study aims to analyze in the mouse the effect of the stage of the estrous cycle at the time of pregnant mare's serum gonadotropin (PMSG) injection on fertilization of ovulated cumulus-enclosed oocytes and later embryo development in vitro to the blastocyst stage. Quality of blastocysts was evaluated by staining and counting of total number of nuclei, mitotic index, percentage of apoptotic nuclei, and cell allocation to the inner cell mass (ICM) and trophectoderm (TE) lineage. Superovulation of hybrid (C57Bl/6JIco female x CBA/JIco male) female mice of 4-6 weeks of age was induced by a priming injection of PMSG at different stages of the estrous cycle followed after a 48-hr interval by human chrorionic gonadotropin. Our data indicate that injection of PMSG at the estrus phase gives the best outcome whereas injection of PMSG at the diestrus-1 or diestrus-2 phase provides the worst results. In fact, (1) total number of oocytes ovulated, number of ovulated oocytes enclosed by cumulus cells, and number of TE cells in day-5 blastocysts were significantly lower in diestrus-1 females than in estrus, diestrus-2 and proestrus mice; (2) percentage of day-5 blastocysts and total number of cells in day-5 blastocysts were lower in diestrus-1 and diestrus-2 females than in estrus and proestrus mice; and (3) percentage of apoptotic nuclei in day-5 blastocysts was lower in estrus mice than in diestrus-1, diestrus-2, or proestrus females. These data endorse previous studies suggesting that administration of gonadotropins in mice should be synchronized with the innate estrous cycle of females.

Calcium or Resistant Starch Does Not Affect Colonic Epithelial Cell Proliferation Throughout the Colon in Adenoma Patients: A Randomized Controlled Trial

Patients with a history of sporadic adenomas have increased epithelial cell proliferative activity, an intermediate risk marker for colorectal cancer. Reduction of proliferation by dietary intervention may reflect a decreased colorectal cancer risk. To evaluate whether calcium or resistant starch could reduce proliferative activity throughout the colon, we performed a randomized controlled trial in 111 sporadic adenoma patients. Patients received two placebos, 1 g of calcium + placebo, or 30 g of amylomaize (19 g of resistant starch) + placebo. After 2 mo, biopsies were collected from the cecum, transverse and sigmoid colon, and rectum during colonoscopy. Epithelial cell proliferation was determined by dividing the number of 5-bromo-2-deoxyuridine-labeled nuclei by the total number of nuclei × 100 (labeling index, LI). LI of luminal, mid, and basal compartments was determined. Twenty-five patients dropped out. In the remaining 86 patients (28 treated with placebo, 30 with calcium + placebo, and 28 with resistant starch + placebo), no difference was observed in total LI, the LI of the three compartments, or the crypt length in the four areas of the colorectum. Colonic epithelial cell proliferative activity throughout the colon of sporadic adenoma patients is not affected by supplementation with 1 g of calcium or 19 g of resistant starch.

Analytical formulae connecting the “real” and the “apparent” nucleation rate and the nuclei number concentration for atmospheric nucleation events

A simple yet relatively accurate analytical formula has been derived between the “real” atmospheric nucleation rate and the rate at which the resulting clusters, or nuclei, appear at some larger size (the “apparent” nucleation rate) as a result of their growth by condensation. In addition, another analytical formula was derived that connects the nucleation rate and the total nuclei concentration in a desired size range. The derived formulae are applicable to situations in which there are no major fluctuations in the pre-existing particle size distribution or in the concentration of vapours responsible for the nuclei growth, and in which the total nuclei number concentration remains sufficiently low (<10 5–10 6 nuclei cm −3) to prevent effective self-coagulation between the nuclei. With the help of these formulae, an explicit nucleation scheme can be included into an atmospheric model without the requirement that the modelled particle diameter range must be extended down to one nanometer. In field measurements only the “apparent” nucleation rate can currently be determined. The derived formulae provide a means to convert this rate to a “real” nucleation rate, making it possible to test more rigorously the viability of different nucleation theories under atmospheric conditions.

5-Fluorouracil induces autophagic degeneration in rat oral keratinocytes.

In this study, we investigated the effect of 5-fluorouracil (5-FU) on the keratinocytes of oral epithelium. Female Lewis rats were given 5-FU i.v. and were killed 12, 24 or 36 h after injection. The buccal mucosa was dissected. The number of nuclei with DNA strand breaks and the total number of nuclei per volume of the epithelial basal cell layer was estimated using terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling. Epithelial cells were analysed by flow cytometry, transmission electron microscopy and a dye exclusion test. The number of cells with DNA strand breaks increased in 5-FU treated rats. Flow cytometry showed a decrease in cell size and an increase in granularity with increasing doses of 5-FU. Dye exclusion gave no indication of degenerate cell membranes. By transmission electron microscopy, the cells showed evidence of degeneration, shrinkage and loss of cell-to-cell contact. Vacuolation was extensive and, in contrast to apoptotic cells, nuclear chromatin condensation seemed to occur centrally in the nuclei. The results show that 5-FU treatment in vivo induces alterations in rat oral keratinocytes that are consistent with autophagic degeneration.

Formation of n-alcohol crystallites from solution

Kinetics of heterogeneous nucleation of n-alcohols (C20OH and C22OH) on vapor-deposited thin films of fatty acid is studied both experimentally and theoretically. A kinetic model describing the three-dimensional nucleation and subsequent growth on active centers is solved numerically. The basic characteristics of nucleation process, such as nucleation rate and the total number of nuclei on unit surface, are determined from the distribution function. Depletion of active centers on template film has been incorporated into our computation. The interfacial energy was chosen to get best coincidence between theoretical and experimental data of the total number of nuclei, which gives 0.0029 J m−2 for C20OH and 0.00285 J m−2 for C22OH, respectively.

THE EFFECT OF ALTERNATING PERIODS OF LOADING AND UNLOADING ON SATELLITE CELL PROLIFERATION IN ADULT QUAIL MUSCLE

This study tested the hypothesis that hypertrophic adaptation following previous loading-unloading periods doesn't require satellite cell activation but results in increased protein accumulation and expression of muscle regulatory factors. The left wing of 18 Japanese quail received a stretch overload corresponding to approximately 10% bodyweight, while the contralateral side served as an intra-animal control. The first group of birds received stretch for 14 days (S14), after which they were sacrificed. The second group underwent a 14-day unloading period after the initial 14-day stretch (U14). The third group of birds was reloaded for 7 days (R7), while the fourth group was reloaded for 14 days (R14) subsequent to the 28 days loading-unloading intervention. Muscle weight increased similarly after 14 days of weighting (142%) and after 7 (143%) or 14 (136%) days of reloading relative to the intra-animal control muscles. Experimental muscles from group U14 had atrophied relative to group S14, but they were still 44% larger than the intra-animal control. Satellite cells were labeled during initial weighting in group S14 or during reweighting in groups R7 and R14 using a constant release BrdU pellet. Nuclei that were immunopostive for BrdU were visualized by immunocytohemistry and the percent of labeling was calculated relative to the total number of nuclei in each muscle cross-section. BrdU positive nuclei (satellite cells) represented 80% of the total myonuclei pool after 14 days of loading and this was similar to the level of satellite cell activation after 7 days of reloading. These data suggest that satellite cells proliferate and are involved in hypertrophic adaptations following unloading. Funded by NIH AG17143

Changes in tissue cellularity are associated with growth enhancement in genetically modified arctic char (Salvelinus alpinus L.) carrying recombinant growth hormone gene.

Biochemical and histological analyses were used to study the number and size of cells (cellularity) in tissues of fast-growing, genetically modified Arctic char (Salvelinus alpinus L.), overexpressing sockeye salmon (Oncorhynchus nerka) growth hormone gene (OnGH1). DNA contents of muscle, heart, and liver were compared in transformed, sibling (age control) and 1 year older (size control) char. Total white muscle cross-sectional area, white muscle fiber number, and total nuclei number within the muscle tissue were determined from one complete half-section of each fish. The analyzed tissues responded differently to growth hormone overproduction. In muscle tissue of OnGH1-transformed char, the enhanced growth was clearly associated with proliferation of muscle cells (hyperplasia), whereas in heart tissue both cell proliferation and increase in cell size (hypertrophy) were enhanced. The relative DNA concentration in the liver of transformed char was significantly greater than that of control fish, suggesting reduction in size of hepatic cells.

MITOTIC ACTIVITY OF THE PARS INTERMEDIA IN THE FEMALE MOUSE: AGE-ASSOCIATED VARIATIONS IN PROLIFERATION RATE AND CIRCADIAN PERIODICITY

We previously reported daily variations in the mitotic activity of the endocrine cells in the pars intermedia of 21- and 28-day-old male mice. Since cellular proliferation might be affected by factors such as sex and age, we undertook the present experiments to study the mitotic activity of the pars intermedia from 14-, 28-, and 150-day-old female mice. Inbred C3H/S mice, grouped according to age, were housed under standard conditions (12h each of light and dark [LD 12:12]) for periodicity analysis and were killed in lots of 5–11 animals every 4h over a single 24h cycle, with each mouse receiving 2 μg/g of colchicine 4h before decapitation. Pituitaries were excised, extracted, fixed in buffered formaldehyde, embedded in celloidin-paraffin, sectioned at 5 μm, and stained with hematoxylin and eosin. We counted the total number of nuclei to estimate the total number of cells monitored and then calculated the mitotic index (metaphases/1000 nuclei). Differences were analyzed for statistical significance by the Student t test. While the 14-day-old animals manifested no significant changes in mitotic activity during the 24h cycle, the 28- and 150-day-old mice showed higher mitotic indices during the period of darkness. The average mitotic activity over the entire cycle, however, was higher in the two groups of younger animals than in the 150-day-old mice. Moreover, the averages for the 28-day-old females were higher than the corresponding values previously reported by us for male mice of the same age. (Chronobiology International, 17(6), 751–756, 2000)

A convenient method for the evaluation of anti-tumor agents affecting the cell cycle

Mitotic index (MI), defined as the ratio (%) of the mitotic-phase-arrested cell number to the total cell number, is higher in the presence of colcemid than in its absence. MI is reduced by anti-tumor agents used in conjunction with colcemid. The ratio of MI, which is defined by the dose of colcemid to that of the supplement with etoposide as an anti-tumor agent and is designated MIR, was 10% at an exposure of 2h, suggesting that etoposide blocks the cell cycle before 2h of the mitotic phase. Thus, we established a convenient method to identify a target point in the cell cycle for anti-tumor agents using colcemid. RBL-2H3, a mammalian cell line, exhibited a large number of 2-fold swollen nuclear envelopes after exposure to etoposide. The G 2-index, which is the ratio of the number of swollen nuclei to the total number of nuclei, was higher when the cells were incubated with etoposide than without it. In this study, we suggest that the measurement of the G 2-index contributes to the screening of putative anti-tumor agents.

Nucleation on active sites: evolution of size distribution

Transient 3D substrate nucleation and growth from the vapor phase on the active sites is studied. The set of kinetic equations describing the formation of nuclei, including the depletion of active sites during nucleation, has been solved numerically within standard nucleation theory to obtain the time-dependent size distribution function of nuclei. Knowing the size distribution function, the basic characteristics of nucleation process (such as nucleation rate, the total number of nuclei formed on the active sites) are determined. It is shown that the evolution of the size distribution function up to the large cluster sizes (40 000 molecules in the cluster) is a complex process. At sufficiently long time, maximum on size distribution (typical for heterogeneous nucleation) appears. The integrated cluster flux (i.e., the number of nuclei greater than given cluster size) reaches for sufficiently long time its stationary value, which is equal to the number of active sites.

A Convenient Method for the Evaluation of Anti-Tumor Agents Affecting the Cell Cycle.

Mitotic index (MI), defined as the ratio (%) of the mitotic-phase-arrested cell number to the total cell number, is higher in the presence of colcemid than in its absence. MI is reduced by anti-tumor agents used in conjunction with colcemid. The ratio of MI, which is defined by the dose of colcemid to that of the supplement with etoposide as an anti-tumor agent and is designated MIR, was 10% at an exposure of 2h, suggesting that etoposide blocks the cell cycle before 2h of the mitotic phase. Thus, we established a convenient method to identify a target point in the cell cycle for anti-tumor agents using colcemid. RBL-2H3, a mammalian cell line, exhibited a large number of 2-fold swollen nuclear envelopes after exposure to etoposide. The G2-index, which is the ratio of the number of swollen nuclei to the total number of nuclei, was higher when the cells were incubated with etoposide than without it. In this study, we suggest that the measurement of the G2-index contributes to the screening of putative anti-tumor agents.

Transmembrane Tumor Necrosis Factor (TNF)-α Inhibits Adipocyte Differentiation by Selectively Activating TNF Receptor 1

Tumor necrosis factor alpha (TNFalpha) is a potent cytokine with multiple biological activities and exists in two forms as follows: a 17-kDa soluble form that is a cleaved product of the 26-kDa transmembrane form (mTNFalpha). It has been suggested that the transmembrane form of TNFalpha is mainly responsible for localized responses via cell-cell contact. Here, we have examined the activities of transmembrane TNFalpha in cultured adipocytes. A non-cleavable transmembrane form of TNFalpha (mTNFDelta1-9K11E) was expressed in several preadipocyte cell lines using retroviral gene transfer. In wild type preadipocytes carrying both TNF receptors, expression of mTNFDelta1-9K11E resulted in inhibition of the differentiation program. The extent of this varied depending on the nature and strength of the adipogenic stimuli. The TNF receptor responsible for this function was determined by expressing mTNFDelta1-9K11E in preadipocyte cell lines lacking either TNF receptor 1 (TNFR1), 2 (TNFR2), or both. In order to confirm the results in the same cellular background, TNF receptors were also reconstituted in the cell lines lacking corresponding receptors. These experiments demonstrated that TNFR1 was necessary and sufficient for mediating mTNFDelta1-9K11E-induced inhibition of adipogenesis and that this action was similar to that of soluble TNFalpha. In conclusion, our results indicate that mTNFDelta1-9K11E is biologically active in cultured adipocytes and can alter the adipogenic program of these cells by selectively activating TNFR1. This may have physiological implications where local TNFalpha actions are thought to be generated at sites such as adipose tissue.

Proliferation, C- myc, and cyclin D1 expression in diffuse alveolar damage: potential roles in pathogenesis and implications for prognosis

In this study, we compared expression of DNA topoisomerase IIα, a marker of cellular proliferation, c- myc, and cyclin D1 in lung biopsy specimens showing diffuse alveolar damage (DAD) with control lung tissues. We subsequently correlated DNA topoisomerase IIα, c- myc, and cyclin D1 expression with survival. We hypothesized that poor outcome may correlate with a higher proliferation index, and that c- myc and cyclin D1 activation are potentially important regulators of both proliferation and apoptosis in DAD. Immunohistochemical stains for c- myc, cyclin D1, and DNA topoisomerase IIα were performed on 10 cases of DAD (15 cases for DNA topoisomerase IIα) and 10 control lungs. A proliferation index for each case was calculated by dividing the number of nuclei expressing DNA topoisomerase IIα by the total number of nuclei counted. The percentages of alveolar pneumocytes and interstitial cells staining positively for c- myc and cyclin D1 were estimated. The average proliferation index (DNA topoisomerase IIα index) in DAD (0.16 ± 0.06, n = 15) was significantly greater than in control lungs (0.00 ± 0.01, n = 10) ( P < .0001). The average proliferation index of patients with DAD who died of respiratory failure (0.18 ± 0.05, n = 9) was significantly greater than the average proliferation index of patients whose respiratory disease resolved or stabilized (0.11 ± 0.05, n = 5) ( P < .03). Expression of c- myc in alveolar pneumocytes and interstitial cells was more intense and slightly more widespread in cases of DAD compared with control lungs. In 9 of 10 cases of DAD, cyclin D1 expression was present in up to 30% of alveolar pneumocytes and up to 10% of interstitial cells. No staining for cyclin D1 was present in control lungs. These results show that the proliferation index in DAD potentially correlates with patient survival. Furthermore, enhanced expression of c- myc and cyclin D1 may contribute to dysregulation of cellular proliferation and apoptosis observed in DAD.

Growth equations for skeletal muscle derived from the cytonuclear ratio and growth constraining supplementary functions

AbstractFor purely hypertrophic muscle it is postulated that the growth rate in number of nuclei is proportional to the cytoplasmic mass per nucleus multiplied by a growth constraining supplementary function. Growth constraint depends on the distance from any one of the limit number of nuclei, the limit muscle mass or the limit cytoplasmic mass per nucleus. Furthermore, theory and evidence are presented for a power (allometric) relationship between total number of nuclei (n) and muscle mass (m) given by the equation n = gmh. Evidence points to two clusters of values for h, one in the vicinity of h = 2/3 and the other h = 1/2. Both may depend on a linear relationship between number of nuclei inside muscle fibre and fibre cross-sectional area. The difference between the two situations can be derived from basic assumptions on either local or systemic diffusion mediated control of the number or division of satellite cell nuclei, leading directly to values of h either equal to 2/3 or V2. For likely values of h and suitable choices of growth constraints, almost all well known growth functions in the literature are derived as potentially applicable to total number of nuclei, or muscle mass or their ratio. Muscle mass growth will show a sigmoidal form for h = 1. This explains sigmoidal growth in body mass as it is mostly dominated by muscle mass. A possible linear growth phase before maturity is explicable from the cessation of either length (h = 1) or nuclear (h = 0) growth in muscle fibres, while cytoplasmic growth continues to maturity. Furthermore, two rat examples indicate that whole body protein growth can be described by the equations derived for muscle mass growth.

Proliferating cell nuclear antigen expression in peribiliary glands of stone-containing intrahepatic bile ducts.

All cases of hepatolithiasis showed features of chronic proliferative cholangitis, and it has been speculated that the atypical glandular proliferation might be a precursor to overt cholangiocarcinoma. Proliferative cell nuclear antigen (PCNA) is a nuclear protein synthesized in the G1/S phase of the cell cycle and therefore is related to cell proliferative activity. In an attempt to assess the activity of cell proliferation of stone-containing intrahepatic bile ducts, we conducted a study using immunohistochemical staining with monoclonal antibody to score PCNA in intrahepatic bile ducts. Thirty patients (10 men, 20 women; mean age 52.4 years) having hepatolithiasis surgically resected were studied. Ten stone-free patients served as controls. All 40 specimens were immunostained for PCNA using PC 10 monoclonal antibody. PCNA of both stone-containing and stone-free intrahepatic bile ducts were assessed by counting positive staining nuclei per 500 cells and expressed as labeling index (LI), ie, percentage of positive nuclei to the total number of nuclei. The PCNA LI in stone-free intrahepatic bile ducts was generally low: 10.0+/-13.2%, 10.4+/-10.7% and 7.9+/-9.6% for extramural glands, intramural glands, and epithelial lining, respectively. In contrast, the PCNA LI for stone-containing intrahepatic bile ducts were significantly higher than those of controls (P < 0.001): 49.4+/-8.3%, 40.6+/-7.0% and 34.1+/-6.8% for extramural glands, intramural glands, and epithelial lining, respectively. The extramural glands had a significantly higher PCNA LI (P < 0.001) than the intramural glands and controls. Hyperplasia was found in all specimens, while dysplasia was found in six of 30 cases with hepatolithiasis. The dysplastic cells also had a higher PCNA LI (P < 0.001) than the hyperplastic cells and normal epithelium. Our findings showed that there is marked increase of activity of cell proliferation in stone-containing intrahepatic bile ducts. It is well known that genetic mutations are facilitated in proliferating cells. Therefore, our results suggest that the high epithelial turnover in dysplastic cells and extramural glands had higher potential for proliferation and neoplastic transformation in long-standing untreated hepatolithiasis.